Light-emitting device, light-emitting apparatus, electronic apparatus, and lighting device

Abstract

To improve reliability of a light-emitting device.SOLUTION: A light-emitting device having a light generation layer, contains: a light emission material; and a first organic chemical compound, in which the light emission material is an organic metal complex having a center metal and a ligand. One ligand includes a skeleton of binding a ring A1 and a pyridine ring. The ring A1 expresses an aromatic ring or a complex aromatic ring. The pyridine ring includes an alkyl group of 1 to 6 deuterium-substituted carbons. The ligand is arranged to the center metal in any one of atoms having the ring A1 and nitrogen in the pyridine ring. The first organic chemical compound includes: an electron transportation skeleton; and a first substitution group and a second substitution group coupled to the electron transportation skelton, respectively. The electron transportation skelton includes the complex aromatic ring having two or more nitrogen, the first substitution group is a group having one or both of the aromatic ring and the complex aromatic ring. The second substitution includes a skelton having a positive hole transport. The minimum triplet excited state of the first organic chemical compound is located in the first substitution group.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a light-emitting device, a light-emitting apparatus, an electronic device, and a lighting apparatus. Note that an embodiment of the present invention is not limited to the above technical field. The technical field of an embodiment of the present invention disclosed in the present specification and the like relates to an object, a method, or a manufacturing method. Alternatively, an embodiment of the present invention relates to a process, a machine, a manufacture, or a composition of matter. Therefore, more specifically, examples of the technical field of an embodiment of the present invention disclosed in the present specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a storage device, an imaging device, a driving method thereof, or a manufacturing method thereof. [Background technology]

[0002] Light-emitting devices (organic EL elements) that utilize electroluminescence (EL) using organic compounds are becoming more and more practical. The basic structure of these light-emitting devices is a pair of electrodes sandwiching an organic compound layer (EL layer) containing a light-emitting material between them. By applying a voltage to this element, carriers are injected, and the recombination energy of the carriers is utilized to emit light from the light-emitting material.

[0003] Since such light-emitting devices are self-emitting, they have higher visibility than liquid crystal displays and are suitable as display pixels. Another major advantage of displays using such light-emitting devices is that they do not require a backlight and can be made thin and lightweight. Another characteristic is that they have an extremely fast response time.

[0004] In addition, these light-emitting devices can have light-emitting layers formed continuously in two dimensions, making it possible to emit light in a planar form. This is a feature that is difficult to obtain with point light sources such as incandescent light bulbs or LEDs, or linear light sources such as fluorescent lamps, making them highly valuable as planar light sources for lighting and other applications.

[0005] Thus, displays or lighting devices using light-emitting devices are suitable for use in a variety of electronic devices, and research and development is ongoing to find light-emitting devices with better efficiency and life span.

[0006] Although the characteristics of light-emitting devices have improved remarkably, they are still insufficient to meet high demands for all characteristics, including efficiency and durability. In particular, to solve problems such as burn-in, which are unique to organic electroluminescence, it is better to minimize the decrease in efficiency due to degradation.

[0007] Since the characteristics of light-emitting devices are greatly influenced by the light-emitting substance and its peripheral materials, the development of light-emitting substances and peripheral materials has been actively pursued (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2009-23938 A [Non-patent literature]

[0009] [Non-Patent Document 1] Nicholas J. Turro, V. Ramamurthy, JC Scaiano, "MODERN MOLECULAR PHOTOCHEMISTRY OF ORGANIC MOLECULES", UNIVERSITY SCIENCE BOOKS, published February 10, 2010, pp. 204-208 [Non-Patent Document 2] Daisaku TANAKA et al., “Ultra High Efficiency Green Organic Light-Emitting Devices”, Japanese Journal of Applied Physics, Vol. 46, No. 1, 2007, pp. L10-L12 Summary of the Invention [Problem to be solved by the invention]

[0010] As reported in the above-mentioned patent documents, progress has been made in the development of luminescent substances and host materials exhibiting excellent properties, but there is a demand for the development of materials and luminescent devices exhibiting even better properties.

[0011] In view of the above, an object of one embodiment of the present invention is to provide a light-emitting device with high reliability. Another object of one embodiment of the present invention is to provide a light-emitting device with high emission efficiency. Another object of one embodiment of the present invention is to provide a novel light-emitting device.

[0012] Another object of one embodiment of the present invention is to provide a light-emitting device, electronic device, or lighting device with a long lifetime.Another object of one embodiment of the present invention is to provide a light-emitting device, electronic device, or lighting device with low power consumption.Another object of one embodiment of the present invention is to provide a novel light-emitting device, electronic device, or lighting device.

[0013] Note that the description of these problems does not preclude the existence of other problems. One embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than these can be extracted from the description of the specification, drawings, and claims. [Means for solving the problem]

[0014] One embodiment of the present invention includes an anode, a cathode, and a light-emitting layer. The light-emitting layer is located between the anode and the cathode. The light-emitting layer includes a light-emitting substance and a first organic compound. The light-emitting substance is an organometallic complex having a central metal and a ligand, and at least one of the ligands has a ring A 1 and a pyridine ring are bonded to each other, and ring A 1 represents an aromatic ring or a heteroaromatic ring, the pyridine ring has a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the ligand is ring A 1and the nitrogen of the pyridine ring are coordinated to a central metal, the first organic compound has an electron-transporting skeleton, and a first substituent and a second substituent, each of which is bonded to the electron-transporting skeleton, the electron-transporting skeleton has a heteroaromatic ring having two or more nitrogens, the first substituent is a group having one or both of an aromatic ring and a heteroaromatic ring, the second substituent has a skeleton having hole-transporting properties, and the lowest triplet excited state of the first organic compound is localized in the first substituent.

[0015] Another embodiment of the present invention is a light-emitting device including an anode, a cathode, and a light-emitting layer. The light-emitting layer is located between the anode and the cathode. The light-emitting layer includes a light-emitting substance and a first organic compound. The light-emitting substance is an organometallic complex including a central metal and ligands, at least one of the ligands has a structure represented by general formula (L1). The first organic compound is an organic compound represented by general formula (G10).

[0016] [ka]

[0017] In the general formula (L1), * represents a bond to the central metal, a dashed line represents coordination to the central metal, and ring A 1 represents an aromatic ring or a heteroaromatic ring, R 1 ~R 4 At least one of the groups is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring. In addition, in the general formula (G10), ring B represents a heteroaromatic ring having two or more nitrogen atoms, and Ar 1 and Ar 2 each independently represents an aromatic ring or a heteroaromatic ring; α and β each independently represent a substituted or unsubstituted phenyl group; Ht uni represents a skeleton having a hole transporting property; n and m each independently represent an integer of 0 to 4.

[0018] Another embodiment of the present invention is a light-emitting device including an anode, a cathode, and a light-emitting layer. The light-emitting layer is located between the anode and the cathode. The light-emitting layer includes a light-emitting substance and a first organic compound. The light-emitting substance is an organometallic complex represented by General Formula (G1). The first organic compound is an organic compound represented by General Formula (G10).

[0019] [ka]

[0020] In the general formula (G1), M represents a central metal, the dashed line represents coordination, and the ring A 1 and Ring A 2 each independently represents an aromatic ring or a heteroaromatic ring; R 1 ~R 4 at least one of R is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring; R 5 ~R 8 each independently represents any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring, and k represents an integer of 0 to 2. In addition, in the general formula (G10), ring B represents a heteroaromatic ring having two or more nitrogen atoms, and Ar 1 and Ar 2 each independently represents an aromatic ring or a heteroaromatic ring; α and β each independently represent a substituted or unsubstituted phenyl group; Ht uni represents a skeleton having a hole transporting property; n and m each independently represent an integer of 0 to 4.

[0021] One embodiment of the present invention is a light-emitting device including an anode, a cathode, and a light-emitting layer. The light-emitting layer is located between the anode and the cathode. The light-emitting layer includes a light-emitting substance and a first organic compound. The light-emitting substance is an organometallic complex represented by General Formula (G2). The first organic compound is an organic compound represented by General Formula (G10).

[0022] [ka]

[0023] In the general formula (G2), M represents a central metal, the dashed line represents a coordination group, Q represents oxygen or sulfur, and X 1 ~X 8 each independently represents either nitrogen or carbon (including CH), R 1 ~R 4 at least one of R is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring; R 5 ~R 14 each independently represents hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring, and k represents an integer of 0 to 2. In addition, in general formula (G10), ring B represents a heteroaromatic ring having two or more nitrogen atoms, and Ar 1 and Ar 2 each independently represents an aromatic ring or a heteroaromatic ring; α and β each independently represent a substituted or unsubstituted phenyl group; Ht uni represents a skeleton having a hole transporting property; n and m each independently represent an integer of 0 to 4.

[0024] Another embodiment of the present invention is a light-emitting device in which the lowest triplet excitation energy of the first organic compound is higher than the lowest triplet excitation energy of the organometallic complex in any of the above structures.

[0025] Another embodiment of the present invention is a light-emitting device having any of the above structures, in which a difference between the lowest triplet excitation energy of the first organic compound and the lowest triplet excitation energy of the organometallic complex is greater than 0 eV and less than or equal to 0.40 eV.

[0026] Another embodiment of the present invention is a light-emitting device in which the central metal in any of the above structures is iridium.

[0027] Another embodiment of the present invention is a light-emitting device in which, in each of the above structures, the heteroaromatic ring having two or more nitrogen atoms is represented by any of structural formulas (B-1) to (B-32).

[0028] [ka]

[0029] Another embodiment of the present invention is a light-emitting device including the light-emitting device having any of the above structures and a transistor or a substrate.

[0030] Another embodiment of the present invention is an electronic device including a light-emitting device having any of the above structures and a detection unit, an input unit, or a communication unit.

[0031] Another embodiment of the present invention is a lighting device including a light-emitting device having any of the above structures and a housing. Effect of the Invention

[0032] According to one embodiment of the present invention, a highly reliable light-emitting device can be provided. According to another embodiment of the present invention, a light-emitting device with high emission efficiency can be provided. According to another embodiment of the present invention, a novel light-emitting device can be provided.

[0033] According to one embodiment of the present invention, a light-emitting device, electronic device, or lighting device with a long lifetime can be provided. According to one embodiment of the present invention, a light-emitting device, electronic device, or lighting device with low power consumption can be provided. According to one embodiment of the present invention, a novel light-emitting device, electronic device, or lighting device can be provided.

[0034] Note that the description of these effects does not preclude the existence of other effects. One embodiment of the present invention does not necessarily have all of these effects. Effects other than these can be extracted from the description in the specification, drawings, and claims. [Brief description of the drawings]

[0035] [Figure 1] 1A to 1E are diagrams illustrating a configuration of a light-emitting device according to an embodiment. [Diagram 2] 2A to 2D are diagrams illustrating a light-emitting device according to an embodiment. [Diagram 3] 3A to 3C are diagrams illustrating a method for manufacturing a light emitting device according to an embodiment. [Figure 4] 4A to 4C are diagrams illustrating a method for manufacturing a light emitting device according to an embodiment. [Diagram 5] 5(A) to 5(D) are diagrams illustrating a method for manufacturing a light emitting device according to an embodiment. [Figure 6] 6A to 6C are diagrams illustrating a light emitting device according to an embodiment. [Figure 7] 7A to 7F are diagrams illustrating a light emitting device according to an embodiment. [Figure 8] 8(A) and 8(B) are diagrams illustrating a light emitting device according to an embodiment. [Figure 9] 9A to 9E are diagrams illustrating electronic devices according to an embodiment. [Figure 10] 10A to 10E are diagrams illustrating electronic devices according to an embodiment. [Figure 11] 11A and 11B are diagrams illustrating an electronic device according to an embodiment. [Figure 12] 12(A) and 12(B) are diagrams illustrating an illumination device according to an embodiment. [Figure 13] FIG. 13 is a diagram illustrating a lighting device according to an embodiment. [Figure 14] 14A to 14C are diagrams illustrating a light emitting device and a light receiving device according to an embodiment. [Figure 15] FIG. 15 shows the luminance-current density characteristics of the light-emitting device 1 and the light-emitting device 2. [Figure 16] FIG. 16 shows the current efficiency-luminance characteristics of the light-emitting device 1 and the light-emitting device 2. [Figure 17] FIG. 17 shows the luminance-voltage characteristics of the light-emitting device 1 and the light-emitting device 2. [Figure 18] FIG. 18 shows the current-voltage characteristics of the light-emitting device 1 and the light-emitting device 2. [Figure 19] FIG. 19 shows the electroluminescence spectra of Light-Emitting Device 1 and Light-Emitting Device 2. [Figure 20] FIG. 20 is a diagram showing changes in luminance with respect to the driving time of light-emitting device 1 and light-emitting device 2. In FIG. [Figure 21] FIG. 21 shows the luminance-current density characteristics of the light-emitting device 3 and the comparative light-emitting devices 4 to 6. [Figure 22] FIG. 22 shows the current efficiency-luminance characteristics of the light-emitting device 3 and the comparative light-emitting devices 4 to 6. [Diagram 23] FIG. 23 shows the luminance-voltage characteristics of the light-emitting device 3 and the comparative light-emitting devices 4 to 6. [Figure 24] FIG. 24 shows the current-voltage characteristics of the light-emitting device 3 and the comparative light-emitting devices 4 to 6. [Diagram 25] FIG. 25 shows the electroluminescence spectra of Light-Emitting Device 3 and Comparative Light-Emitting Devices 4-6. [Figure 26] FIG. 26 shows the luminance-current density characteristics of the light-emitting device 3 and the comparative light-emitting devices 4, 7 and 8. [Figure 27] FIG. 27 shows the current efficiency-luminance characteristics of the light-emitting device 3 and the comparative light-emitting devices 4, 7 and 8. [Figure 28] FIG. 28 shows the luminance-voltage characteristics of Light-Emitting Device 3 and Comparative Light-Emitting Devices 4, 7 and 8. [Figure 29]FIG. 29 shows the current-voltage characteristics of Light-Emitting Device 3 and Comparative Light-Emitting Devices 4, 7 and 8. [Diagram 30] FIG. 30 shows the electroluminescence spectra of Light-Emitting Device 3 and Comparative Light-Emitting Devices 4, 7 and 8. [Diagram 31] FIG. 31 is a graph showing the change in luminance with respect to the driving time of the light-emitting device 3 and the comparative light-emitting devices 4 to 6. In FIG. [Diagram 32] FIG. 32 is a graph showing the change in luminance with respect to the driving time of the light-emitting device 3 and the comparative light-emitting devices 4, 7 and 8. In FIG. [Diagram 33] 33(A) to 33(C) are diagrams showing the analysis results based on the calculation of 8mpTP-4mDBtPBfpm. [Diagram 34] 34(A) to 34(C) are diagrams showing the analysis results by calculation of the organic compound represented by the structural formula (216). [Diagram 35] 35(A) to 35(C) are diagrams showing the analysis results based on the calculation of 8BP-4mDBtPBfpm. [Diagram 36] FIG. 36 is a diagram showing the measurement results of the emission spectra of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d23. [Figure 37] FIG. 37 is a diagram showing the measurement results of the emission spectrum of 8mpTP-4mDBtPBfpm-d13. [Figure 38] FIG. 38 is a diagram showing the measurement results of the emission spectrum of 8mpTP-4mDBtPBfpm-d10. [Figure 39] FIG. 39 is a diagram showing the measurement results of the luminescence lifetime of 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d23. [Diagram 40] FIG. 40 shows the luminance-current density characteristics of the light-emitting device 9 and the light-emitting device 10. [Diagram 41] FIG. 41 shows the current efficiency-luminance characteristics of the light-emitting device 9 and the light-emitting device 10. [Diagram 42] FIG. 42 shows the luminance-voltage characteristics of the light-emitting device 9 and the light-emitting device 10. As shown in FIG. [Diagram 43] FIG. 43 shows the current-voltage characteristics of the light-emitting device 9 and the light-emitting device 10. [Diagram 44] FIG. 44 shows the electroluminescence spectra of light-emitting device 9 and light-emitting device 10. [Diagram 45] FIG. 45 is a diagram showing the change in luminance with respect to the driving time of light-emitting device 9 and light-emitting device 10. In FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] The embodiments will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that the modes and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0037] In the configuration of the invention described below, the same parts or parts having similar functions are denoted by the same reference numerals in different drawings, and the repeated explanations are omitted. In addition, when referring to similar functions, the same hatch pattern may be used and no particular reference numeral may be used.

[0038] In addition, for ease of understanding, the position, size, range, etc. of each component shown in the drawings may not represent the actual position, size, range, etc. Therefore, the disclosed invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings.

[0039] In addition, the words "film" and "layer" can be interchanged depending on the case or situation. For example, the term "conductive layer" can be changed to the term "conductive film". Or, for example, the term "insulating film" can be changed to the term "insulating layer".

[0040] In this specification, etc., a device fabricated using a metal mask or an FMM (fine metal mask, high-definition metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification, etc., a device fabricated without using a metal mask or an FMM may be referred to as a device with an MML (metal maskless) structure.

[0041] In this specification and the like, holes or electrons may be referred to as "carriers". Specifically, a hole injection layer or an electron injection layer may be referred to as a "carrier injection layer", a hole transport layer or an electron transport layer may be referred to as a "carrier transport layer", and a hole block layer or an electron block layer may be referred to as a "carrier block layer". Note that the above-mentioned carrier injection layer, carrier transport layer, and carrier block layer may not be clearly distinguishable from each other depending on their cross-sectional shapes or characteristics. Also, one layer may have two or three functions among the carrier injection layer, carrier transport layer, and carrier block layer.

[0042] In this specification etc., a light-emitting device (also referred to as a light-emitting element) has an EL layer between a pair of electrodes. The EL layer has at least a light-emitting layer. In this specification etc., a light-receiving device (also referred to as a light-receiving element) has at least an active layer that functions as a photoelectric conversion layer between a pair of electrodes. In this specification etc., one of the pair of electrodes may be referred to as a pixel electrode, and the other as a common electrode.

[0043] In this specification, the term "tapered shape" refers to a shape in which at least a part of the side of the structure is inclined with respect to the substrate surface. For example, it is preferable to have a region in which the angle (also called the taper angle) between the inclined side and the substrate surface is less than 90°. The side of the structure and the substrate surface do not necessarily need to be completely flat, and may be substantially planar with a slight curvature or substantially planar with a slight unevenness.

[0044] In this specification, the term "light-emitting device" includes an image display device using a light-emitting device. The term "light-emitting device" may also include a module in which a connector, such as an anisotropic conductive film or TCP (Tape Carrier Package), is attached to a light-emitting device, a module in which a printed wiring board is provided at the end of a TCP, or a module in which an IC (integrated circuit) is directly mounted on a light-emitting device by a COG (Chip On Glass) method. Furthermore, lighting fixtures and the like may have a light-emitting device.

[0045] (Embodiment 1) In this embodiment, a light-emitting device according to one embodiment of the present invention will be described. With the device structure described in this embodiment, a highly reliable light-emitting device can be provided.

[0046] 1(A) shows a schematic cross-sectional view of a light-emitting device 100 having an EL layer including a light-emitting layer between a pair of electrodes. Specifically, the light-emitting device 100 has a structure in which an EL layer 103 is sandwiched between a first electrode 101 and a second electrode 102. The EL layer 103 has at least a light-emitting layer.

[0047] The light-emitting layer is a layer having at least a light-emitting material and a host material. Here, light-emitting materials and host materials that are preferably used in the light-emitting device according to one embodiment of the present invention will be described.

[0048] <Luminous substances> The luminescent material is an organometallic complex having a central metal and a ligand, and at least one of the ligands is a ring A 1 and a pyridine ring are bonded to each other, and ring A 1 represents an aromatic ring or a heteroaromatic ring, and the pyridine ring has an alkyl group having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms is preferably substituted with deuterium. The ligand may be an organometallic complex having a ring A 1 and the nitrogen of the pyridine ring are preferably coordinated to the central metal of the organometallic complex.

[0049] In this specification and the like, the term "coordination" refers to the arrangement of atoms, molecules, or ions around an atom or ion.

[0050] In the present specification and the like, the term "aromatic ring" refers to not only a monocyclic aromatic ring but also a polycyclic aromatic ring formed by condensing a plurality of monocyclic aromatic rings. The term "heteroaromatic ring" refers to not only a monocyclic heteroaromatic ring but also a polycyclic heteroaromatic ring formed by condensing a plurality of monocyclic heteroaromatic rings, and a polycyclic heteroaromatic ring formed by condensing one or more monocyclic aromatic rings with one or more monocyclic heteroaromatic rings.

[0051] The organometallic complex exhibits phosphorescence. By using such an organometallic complex in the light-emitting layer, the light-emitting device 100 can function as a phosphorescent device.

[0052] In the above organometallic complex, the pyridine ring (hereinafter, sometimes simply referred to as pyridine ring) of at least one of the ligands coordinated to the central metal has an alkyl group. Since the alkyl group is an electron donating group, the electron density of the pyridine ring can be increased by introducing the alkyl group into the pyridine ring. This increases the distance between the nitrogen of the pyridine ring and the central metal, so that the HOMO (Highest Occupied Molecular Orbital) level and the LUMO (Lowest Unoccupied Molecular Orbital) level of the organometallic complex are raised (shallowed). When an organometallic complex with a shallow HOMO level is used as a light-emitting material of the light-emitting layer, the hole injection barrier in the light-emitting layer can be reduced, and holes can easily enter the light-emitting layer, so that the driving voltage of the light-emitting device 100 can be reduced. Therefore, the load applied to the light-emitting device 100 during operation can be suppressed, and the reliability of the light-emitting device can be improved. In addition, the light-emitting properties of the organometallic complex can be adjusted by introducing an alkyl group into the organometallic complex.

[0053] In the above organometallic complex, if the number of carbon atoms in the alkyl group of the pyridine ring is too large, the sublimability may decrease. Therefore, in order to prevent the decrease in the sublimability of the organometallic complex, the alkyl group introduced into the pyridine ring is preferably an alkyl group having 1 to 6 carbon atoms.

[0054] In the above organometallic complex, the alkyl group having 1 to 6 carbon atoms in the pyridine ring is preferably deuterium-substituted. The bond dissociation energy of the bond between carbon and deuterium is greater than the bond dissociation energy of the bond between carbon and hydrogen, making the bond stable and difficult to break. Therefore, by introducing a deuterium-substituted alkyl group into the ligand, the ligand can be made more stable than when an alkyl group that is not substituted with deuterium is introduced.

[0055] Furthermore, in the above organometallic complex, the nitrogen of the pyridine ring having an alkyl group having 1 to 6 carbon atoms is coordinated to the central metal. This not only stabilizes the ligand, but also stabilizes the coordination of the ligand to the central metal, thereby stabilizing the organometallic complex using the ligand. Therefore, the use of the organometallic complex can improve the reliability of the light-emitting device.

[0056] In this specification and the like, the terms "deuterated" or "deuterium-substituted" are used when it is necessary to specifically specify that the ratio of deuterium in the hydrogen of a certain compound, partial structure, or group (atomic group) is at least 100 times the natural abundance level. Also, a "deuterium-substituted alkyl group" means that at least one hydrogen in an alkyl group is substituted with deuterium.

[0057] Next, the specific structure of the above-mentioned organometallic complex will be described using a chemical formula. Note that the description of the effects and the like of the above-mentioned organometallic complex also applies to the more specific structures of the organometallic complexes shown below.

[0058] As the organometallic complex, for example, an organometallic complex having a central metal and ligands, at least one of the ligands having a structure represented by the following general formula (L1) can be used.

[0059] [ka]

[0060] In the general formula (L1), * represents a bond to the central metal, a dashed line represents coordination to the central metal, and ring A 1 represents an aromatic ring or a heteroaromatic ring, R 1 ~R 4 At least one of the groups is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring.

[0061] In the ligand represented by the general formula (L1), R 1 and R 4 is preferably hydrogen (including deuterium). 3 is more preferably a deuterium-substituted alkyl group having 1 to 6 carbon atoms. In this case, it is possible to prevent destabilization of coordination to the central metal due to the steric influence of the substituent, and therefore the organometallic complex can be made more stable.

[0062] As the organometallic complex, for example, an organometallic complex represented by the general formula (G1) can be used.

[0063] [ka]

[0064] In the general formula (G1), M represents a central metal, the dashed line represents coordination, and the ring A 1 and Ring A 2 each independently represents an aromatic ring or a heteroaromatic ring; R 1 ~R4 at least one of R is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring; R 5 ~R 8 each independently represents any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring, and k represents an integer of 0 to 2.

[0065] In the organometallic complex represented by the general formula (G1), R 1 and R 4 is preferably hydrogen (including deuterium). 3 is more preferably a deuterium-substituted alkyl group having 1 to 6 carbon atoms. In this case, it is possible to prevent the steric effect of the substituent from hindering coordination to the central metal, and therefore the organometallic complex can be more stabilized.

[0066] In addition, the ring A in the ligand represented by the general formula (L1) 1 and ring A in the organometallic complex represented by general formula (G1) 1 and Ring A 2 More specifically, the aromatic ring and the heteroaromatic ring that can be used in the above-mentioned formula (1) include an aromatic ring having 6 to 13 carbon atoms and a heteroaromatic ring having 2 to 13 carbon atoms. 1 and Ring A 2 Specific examples of the aromatic ring and heteroaromatic ring that can be used include the following structural formulas (A-1) to (A-29). 1 or Ring A 2 When multiple are present, they may be the same or different.

[0067] [ka]

[0068] The aromatic rings and heteroaromatic rings represented by the structural formulas (A-1) to (A-29) are each a ring A 1 and Ring A 2 A specific example of the ring A 1 and Ring A 2 The aromatic rings and heteroaromatic rings that can be used are not limited to those shown above. In addition, the aromatic rings and heteroaromatic rings represented by the above structural formulas (A-1) to (A-29) may be deuterium-substituted.

[0069] In addition, ring A 1 or Ring A 2 may further have a substituent. 1 or Ring A 2 When has a substituent, specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an aryl group having 6 to 13 carbon atoms. When the substituent is an alkyl group having 1 to 6 carbon atoms, it is more preferable that the alkyl group has 1 to 6 carbon atoms and is substituted with deuterium. This can provide the same effect as that obtained by introducing an alkyl group having 1 to 6 carbon atoms and being substituted with deuterium into the pyridine ring.

[0070] As the organometallic complex, for example, an organometallic complex represented by the general formula (G2) can be used.

[0071] [ka]

[0072] In the general formula (G2), M represents a central metal, the dashed line represents a coordination group, Q represents oxygen or sulfur, and X 1 ~X 8 each independently represents either nitrogen or carbon (including CH), R 1 ~R 4 at least one of R is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring; R 5 ~R14 each independently represents hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 13 carbon atoms in a ring; and k represents an integer of 0 to 2.

[0073] In the organometallic complex represented by the general formula (G2), R 1 and R 4 is preferably hydrogen (including deuterium). 3 is more preferably a deuterium-substituted alkyl group having 1 to 6 carbon atoms. In this case, it is possible to prevent the steric effect of the substituent from hindering coordination to the central metal, and therefore the organometallic complex can be more stabilized.

[0074] In order to make the above-mentioned organometallic complex emit phosphorescence more efficiently, the central metal M is preferably a heavy metal from the viewpoint of the heavy atom effect. Therefore, among the above-mentioned organometallic complexes, the organometallic complex in which the central metal M is iridium or platinum is preferable. In addition, since the thermal and chemical stability of the organometallic complex is improved by making the central metal M iridium, it is more preferable to use iridium as the central metal M.

[0075] In the above-mentioned organometallic complexes, specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a hexyl group, etc. Regardless of whether or not there is a description that deuterium substitution is preferable, these groups may be deuterium-substituted.

[0076] In the above-mentioned organometallic complex, specific examples of the deuterium-substituted alkyl group having 1 to 6 carbon atoms include a methyl-d3 group, an ethyl-d5 group, a propyl-d7 group, a 2-propyl-2-d group, an isopropyl-d7 group, a butyl-d9 group, a 2-methyl-1-propyl-1,1-d2 group, an isobutyl-d9 group, a sec-butyl-d9 group, a tert-butyl-d9 group, a pentyl-d 11 Group, isopentyl-d 11Group, hexyl-d 13 Examples of such groups include the following:

[0077] In the above-mentioned organometallic complex, specific examples of the aryl group having 6 to 13 carbon atoms forming a ring include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, an indenyl group, a naphthyl group, a fluorenyl group, etc. These groups may be substituted with deuterium.

[0078] In the above-mentioned organometallic complexes, when the aryl group having 6 to 13 carbon atoms forming a ring further has a substituent, specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an aryl group having 6 to 13 carbon atoms forming a ring. These groups may be substituted with deuterium.

[0079] Specific structural formulas of organometallic complexes that can be used as the luminescent material in the light-emitting device 100 are shown below, although the present invention is not limited thereto.

[0080] [ka]

[0081] [ka]

[0082] Host material As the host material, an organic compound having an electron transporting skeleton, and a first substituent and a second substituent each bonded to the electron transporting skeleton can be used. In the organic compound, the electron transporting skeleton preferably has a heteroaromatic ring having two or more nitrogen atoms, and the first substituent preferably has one or both of an aromatic ring and a heteroaromatic ring. In addition, in the organic compound, the second substituent preferably has a hole transporting skeleton. In addition, in the organic compound, it is preferable that the lowest triplet excited state (i.e., triplet exciton) is localized in the first substituent. Hereinafter, an organic compound having such a structure is referred to as a first organic compound.

[0083] The first organic compound is an organic compound having a T1 level higher than the lowest triplet excitation energy (energy difference between the ground state (S0) and the lowest triplet excited state (T1)) of the organometallic complex that can be used as the above-mentioned light-emitting substance (hereinafter, T1 level). By using such a first organic compound as a host material in the light-emitting layer together with a light-emitting substance, energy can be transferred from the first organic compound in the triplet excited state to the light-emitting substance, so that the light-emitting substance can emit light efficiently.

[0084] In addition, regarding the S1 level (energy difference between the ground state (S0) and the lowest singlet excited state (S1)) or T1 level of an organic compound, when a ν=0→ν=0 transition (0→0 band) between the vibrational levels of the ground state and the excited state is clearly observed in the fluorescence spectrum or phosphorescence spectrum, it is preferable to calculate using the 0→0 band (see, for example, Non-Patent Document 1). In addition, when the 0→0 band is not clear, a tangent line is drawn at the value where the slope of the short wavelength side of the peak in the fluorescence spectrum is maximum, and the energy of the intersection of the tangent line with the horizontal axis (wavelength) or the baseline is taken as the S1 level, and a tangent line is drawn at the value where the slope of the short wavelength side of the peak in the phosphorescence spectrum is maximum, and the energy of the intersection of the tangent line with the horizontal axis (wavelength) or the baseline is taken as the T1 level (see, for example, Non-Patent Document 2). In this specification, each level is measured using the latter method. In addition, when comparing levels, comparison is performed at levels calculated by the same method.

[0085] However, if the T1 level of the first organic compound used as the host material is excessively large compared to the T1 level of the light-emitting material, the energy transfer becomes incomplete, and the efficiency and reliability of the light-emitting device are likely to decrease. Therefore, the difference between the T1 level of the host material and the T1 level of the light-emitting material is preferably greater than 0 eV and less than 0.40 eV, and more preferably greater than 0 eV and less than 0.20 eV. This makes it possible to improve the efficiency and reliability of the light-emitting device.

[0086] The first organic compound has an electron transporting skeleton and a second substituent having a hole transporting skeleton, and therefore the first organic compound can be called an electron transporting material, a hole transporting material, or a bipolar material having both electron transporting and hole transporting properties.

[0087] In addition, in the first organic compound, the lowest triplet excited state is localized in the first substituent. As a result, the lowest triplet excited state is unlikely to be localized in the electron transport skeleton and the hole transport skeleton (second substituent). Therefore, when the first organic compound is used as a host material in a light-emitting device, the deterioration of the electron transport skeleton and the hole transport skeleton of the first organic compound is suppressed. By using such a first organic compound, the reliability of the light-emitting device can be improved.

[0088] In addition, in the first organic compound having the above structure, the LUMO is likely to be distributed in the electron transporting skeleton. As described above, the lowest triplet excited state is localized in the first substituent, so that the position where the LUMO is distributed and the position where the lowest triplet excited state is localized are different from each other. This can increase the stability when the first organic compound is used in a light-emitting device, thereby improving the reliability of the light-emitting device.

[0089] However, in the first organic compound, if the distribution position of the LUMO and the localized position of the lowest triplet excited state are too far apart, the properties as a host material may be insufficient. Therefore, for example, if the distribution position of the LUMO and the localized position of the lowest triplet excited state are adjacent to each other and do not overlap, the organic compound has good properties as a host material and is highly stable.

[0090] In this specification and the like, the lowest triplet excited state (i.e., triplet excitons) can be considered to be localized in a partial structure in which the spin density is distributed in the most stable structure of the lowest triplet excited state of an organic compound. Since the vibrational structure of an organic compound is derived from the partial structure in which the lowest triplet excited state is localized, the partial structure in which the lowest triplet excited state of the organic compound is localized can sometimes be read from the waveform of the emission spectrum of the organic compound.

[0091] Next, a more specific structure of the above-mentioned first organic compound will be described using a chemical formula. Note that the description of the effects of the above-mentioned first organic compound also applies to the more specific structure of the first organic compound shown below.

[0092] As the first organic compound, for example, an organic compound represented by the following general formula (G10) can be used.

[0093] [ka]

[0094] In general formula (G10), ring B represents a heteroaromatic ring having two or more nitrogen atoms, α represents a substituted or unsubstituted o-phenylene group or a substituted or unsubstituted m-phenylene group, Ar 1 and Ar 2 each independently represents an aromatic ring or a heteroaromatic ring; β represents a substituted or unsubstituted phenylene group; Ht uni represents a skeleton having a hole transporting property; n and m each independently represent an integer of 0 to 4.

[0095] In addition, the ring B, which is a partial structure in the above general formula (G10), corresponds to an electron transport skeleton, the substituent represented by the following general formula (S1) corresponds to a first substituent, and the substituent represented by the following general formula (S2) corresponds to a second substituent. In addition, in the general formula (G10), a structure in which one each of the first and second substituents is bonded to the ring B is shown, but is not limited thereto. As long as one or more first substituents and one or more second substituents are bonded to the ring B, it can be used as the first organic compound.

[0096] [ka]

[0097] Next, the details of each partial structure of the first organic compound (the electron transporting skeleton, the first substituent, and the second substituent) will be described.

[0098] <Electron transporting skeleton> A π-electron-deficient heteroaromatic ring can be used as the electron-transporting skeleton (ring B). More specifically, a heteroaromatic ring having two or more nitrogen atoms can be used as the electron-transporting skeleton (ring B). More specifically, the heteroaromatic ring having two or more nitrogen atoms and having 2 to 15 carbon atoms forming the ring is preferable. Specific examples of the π-electron-deficient heteroaromatic ring that can be used as the electron-transporting skeleton include the heteroaromatic rings represented by the following structural formulas (B-1) to (B-32).

[0099] [ka]

[0100] The heteroaromatic rings having two or more nitrogen atoms represented by the structural formulas (B-1) to (B-32) are specific examples of ring B, but ring B is not limited thereto. These rings may be deuterium-substituted. Ring B may have a further substituent in addition to the first and second substituents. When the heteroaromatic ring having two or more nitrogen atoms has a substituent, specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an aryl group having 6 to 13 carbon atoms forming a ring.

[0101] In addition, in the general formula (G10), it is more preferable to use a benzofuropyrimidine ring (structural formulas (B-9) and (B-10)), a benzothienopyrimidine ring (structural formulas (B-21) and (B-22)), or a triazine ring (structural formula (B-5)) as ring B. This can further improve the electron transport properties of the first organic compound. In particular, it is even more preferable to use a benzofuropyrimidine ring (structural formulas (B-9) and (B-10)) or a benzothienopyrimidine ring (structural formulas (B-21) and (B-22)) as ring B, as this can further increase stability.

[0102] When the benzofuropyrimidine ring (benzofuro[3,2-d]pyrimidine ring) represented by structural formula (B-10) and the benzothienopyrimidine ring (benzothieno[3,2-d]pyrimidine ring) represented by structural formula (B-22) are used for ring B, it is more preferable that the substitution position of the first substituent is the 8th position and the substitution position of the second substituent is the 4th position. This can further increase the stability of the organic compound.

[0103] <First Substituent> The first substituent (the substituent represented by the general formula (S1)) has a localized lowest triplet excited state. The first substituent is preferably a group having one or both of an aromatic ring and a heteroaromatic ring. The first substituent is preferably a structure in which either a substituted or unsubstituted o-phenylene group or a substituted or unsubstituted m-phenylene group is bonded to the electron transport skeleton (ring B), and further an aromatic ring or a heteroaromatic ring is linked to the o-phenylene group or the m-phenylene group. By bonding the o-phenylene group or the m-phenylene group in the first substituent to the electron transport skeleton, the first substituent and the electron transport skeleton can be prevented from forming a planar structure, and therefore the conjugated system between the first substituent and the electron transport skeleton can be suppressed from spreading. Therefore, in the first organic compound, the position where the LUMO is distributed and the position where the lowest triplet excited state is localized tend to differ, so that the stability of the first organic compound can be increased and the reliability of the light-emitting device can be improved.

[0104] In the first substituent, Ar 1 and Ar 2 More specifically, aromatic rings having 6 to 13 carbon atoms and heteroaromatic rings having 2 to 13 carbon atoms are preferred as aromatic rings and heteroaromatic rings. This allows proper sublimability to be maintained and decomposition during sublimation purification or vacuum deposition to be suppressed. 1 When there are multiple, they may be the same or different.

[0105] Ar 1 and Ar 2 Specific examples of the aromatic ring that can be used include a benzene ring, a naphthalene ring, a fluorene ring, etc., and specific examples of the heteroaromatic ring include a dibenzofuran ring, a dibenzothiophene ring, a carbazole ring, etc. When the aromatic ring or the heteroaromatic ring further has a substituent, specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms, a polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms, a cyano group, etc.

[0106] In addition, the first substituent, Ar 1 and Ar 2 It is more preferable that the portion constituted by Ar has a linear structure. 1 is more preferably a para-substituted benzene ring, which makes it easier for the conjugated system in the first substituent to be connected, and makes it easier for the lowest triplet excited state to be localized in the first substituent.

[0107] In the first substituent, α, Ar 1 , and Ar 2 For example, a new bond may be formed through oxygen or nitrogen to form a bond between α, Ar 1 , and Ar 2 This makes it easier for the conjugated system in the first substituent to be connected, and makes it easier for the lowest triplet excited state to be localized in the first substituent.

[0108] Therefore, it is more preferable that the first substituent has a structure represented by the general formula (S1-A) or (S1-B). These groups may be deuterium-substituted.

[0109] [ka]

[0110] In the general formulas (S1-A) and (S1-B), L 1 ~L 7 are each independently a partial structure represented by any one of general formulas (L-1) to (L-4), and R 21 ~R 36 each independently represents any one of hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms, a polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms, a cyano group, and an aryl group having 6 to 13 carbon atoms in the ring.

[0111] Specific examples of the first substituent (general formulae (S1), (S1-A) and (S1-B)) include the following structural formulae (S1-1) to (S1-28). These groups may be deuterium-substituted. However, the present invention is not limited to these.

[0112] [ka]

[0113] [ka]

[0114] <Second Substituent> The second substituent (the substituent represented by general formula (S2)) is a group having a hole transporting skeleton, and it is preferable to use a group that can impart hole transporting properties to the first organic compound.

[0115] In the substituent represented by the general formula (S2), when α is a substituted phenyl group, specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, etc. These groups may be substituted with deuterium.

[0116] As the hole transport skeleton, a π-electron-rich heteroaromatic ring can be used. uni represents a hole transporting skeleton. uni Specific examples of the general formulae (Ht-1) to (Ht-15) are given below. These groups may be deuterium-substituted. However, the present invention is not limited to these.

[0117] [ka]

[0118] In the above general formulas (Ht-1) to (Ht-15), Q represents oxygen or sulfur. 10 represents a substituted or unsubstituted aryl group having 6 to 13 carbon atoms. The above general formulae (Ht-1) to (Ht-15) may further have a substituent, and specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, and the like.

[0119] The above is the details of each partial structure (electron transporting skeleton, first substituent, and second substituent) of the first organic compound.

[0120] Specific examples of the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 13 carbon atoms forming a ring that can be used in the first organic compound are the same as the specific examples of the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 13 carbon atoms forming a ring that can be used in the above-mentioned organometallic complex.

[0121] In the first organic compound, specific examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, an isobutoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, a sec-pentyloxy group, a tert-pentyloxy group, a neopentyloxy group, an n-hexyloxy group, an isohexyloxy group, a sec-hexyloxy group, a tert-hexyloxy group, a neohexyloxy group, a cyclohexyloxy group, etc. These groups may be substituted with deuterium.

[0122] In the first organic compound, specific examples of the monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a 1-methylcyclohexyl group, a cycloheptyl group, etc. These groups may be substituted with deuterium.

[0123] In the first organic compound, specific examples of the polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms include a norbornyl group, an adamantyl group, a decalin group, a tricyclodecyl group, etc. These groups may be substituted with deuterium.

[0124] In addition, in the first organic compound, it is more preferable that any one or more of the electron transporting skeleton, the first substituent, and the second substituent are substituted with deuterium. As described above, the bond dissociation energy of the bond between carbon and deuterium is greater than the bond dissociation energy of the bond between carbon and hydrogen, and is stable and difficult to break. Therefore, by substituting any one or more of the electron transporting skeleton, the first substituent, and the second substituent with deuterium, the first organic compound can be more stabilized. Therefore, the reliability of the light-emitting device can be improved.

[0125] As described above, in the first organic compound, since the lowest triplet excited state is localized in the first substituent, it is more preferable that the first substituent is deuterium-substituted. Although the lowest triplet excitation may easily dissociate the carbon-hydrogen bond, the first substituent being deuterium-substituted can prevent the dissociation of the carbon-hydrogen bond due to the lowest triplet excitation. Therefore, by deuterizing the first substituent, the deterioration of the first organic compound can be effectively prevented. Therefore, the reliability of the light-emitting device can be improved.

[0126] In addition, since deuterium is a heavier atom than protium, the vibration amplitude of the carbon-deuterium bond is smaller than that of the carbon-protium bond. Therefore, by substituting the first substituent with deuterium, the intramolecular vibration in the lowest triplet excited state is suppressed. As a result, the rate of thermal deactivation (non-radiative transition) from the triplet excited state of the first organic compound can be slowed down, and by substituting the first substituent with deuterium, energy can be efficiently transferred from the first organic compound to the light-emitting substance in the light-emitting layer. Therefore, the deterioration of the first organic compound is suppressed, and the reliability of the light-emitting device can be improved.

[0127] In addition, when the first organic compound is used as a host material, the hole transporting skeleton of the second substituent may receive holes, so it is more preferable that the second substituent is deuterium-substituted. In some cases, carbon-hydrogen bonds are easily dissociated during the transfer of holes, but the deuterium-substituted second substituent can prevent the dissociation of carbon-hydrogen bonds due to the transfer of holes.

[0128] In addition, the synthesis of an organic compound in which the entire structure of the first organic compound is deuterated has problems such as a complicated route or the need for high temperature and high pressure, etc. Therefore, by using an organic compound in which only one or both of the first and second substituents are selectively deuterated as the first organic compound, which is easier to synthesize, it is possible to reduce the manufacturing cost of the light-emitting device.

[0129] Specific structural formulas of organic compounds that can be used as the host material in the light-emitting device 100 are shown below, although the invention is not limited thereto.

[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] The above is a description of the luminescent material and the host material that can be used in the light-emitting device 100. By using such a luminescent material and a host material in combination in the light-emitting layer, the reliability of the light-emitting device can be improved.

[0134] The light-emitting layer may contain an assist material (second host material) in addition to the light-emitting substance and the host material (first host material). The energy transfer mechanism in the case where a plurality of host materials are used in the light-emitting layer will be described later in the second embodiment.

[0135] Assist materials An example of a material that can be used as the assist material is a second organic compound represented by general formula (G20).

[0136] [ka]

[0137] In general formula (G20), R 201 ~R 214 each independently represents hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms, a substituted or unsubstituted polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 13 carbon atoms forming a ring, or a substituted or unsubstituted heteroaryl group having 3 to 20 carbon atoms forming a ring. 200 and A 201 are each independently any one of a substituted or unsubstituted triphenylenyl group, a substituted or unsubstituted phenanthryl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, and a substituted or unsubstituted terphenyl group, and A 200 and A 201 At least one of is any one of a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthryl group, and a substituted or unsubstituted triphenylenyl group.

[0138] Furthermore, a second organic compound represented by general formula (G21) can be given as a material that can be used as the assist material.

[0139] [ka]

[0140] In the above general formula (G21), A 200 and A 201 are each independently an unsubstituted triphenylenyl group, an unsubstituted phenanthryl group, an unsubstituted β-naphthyl group, an unsubstituted phenyl group, an unsubstituted biphenyl group, or an unsubstituted terphenyl group, and A 200 and A 201 At least one of these is an unsubstituted β-naphthyl group or an unsubstituted triphenylenyl group.

[0141] Specific examples of the alkyl group having 1 to 6 carbon atoms, the aryl group having 6 to 13 carbon atoms forming a ring, the monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms, and the polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms that can be used in General Formula (G20) are the same as the specific examples of the alkyl group having 1 to 6 carbon atoms, the aryl group having 6 to 13 carbon atoms forming a ring, the monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms, and the polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms that can be used in the above-mentioned organometallic complex or first organic compound, respectively.

[0142] Specific examples of the heteroaryl group having 3 to 20 carbon atoms forming a ring that can be used in general formula (G20) include a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzonaphthofuranyl group, a benzonaphthothiophenyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, an indenocarbazolyl group, a dibenzocarbazolyl group, etc. These groups may be substituted with deuterium.

[0143] In the general formula (G20), when the monocyclic saturated hydrocarbon group having 5 to 7 carbon atoms, the polycyclic saturated hydrocarbon group having 7 to 10 carbon atoms, the aryl group having 6 to 13 carbon atoms forming the ring, the heteroaryl group having 3 to 20 carbon atoms forming the ring, the triphenylenyl group, the phenanthryl group, the naphthyl group, the phenyl group, the biphenyl group, or the terphenyl group has a substituent, specific examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted phenyl group, etc. These groups may be substituted with deuterium.

[0144] Specific examples of the organic compounds represented by the above general formulas (G20) and (G21) are shown below.

[0145] [ka]

[0146] [ka]

[0147] Note that the second organic compound that can be used as the assist material is not limited to this, and a material that can be used as a host material described later in Embodiment 2 may be used.

[0148] The light-emitting layers of light-emitting device 100 have been described above.

[0149] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiment modes.

[0150] (Embodiment 2) In this embodiment mode, other structures of the light-emitting device shown in Embodiment Mode 1 will be described with reference to FIGS.

[0151] <Basic structure of light-emitting devices> The basic structure of the light-emitting device will be described below. As described in the first embodiment, a light-emitting device having an EL layer including a light-emitting layer between a pair of electrodes is shown in FIG.

[0152] 1B shows a light-emitting device having a structure (also called a tandem structure) in which a plurality of EL layers (two layers in FIG. 1B) are provided between a pair of electrodes and a charge generation layer 106 is provided between the plurality of EL layers, thereby stacking the plurality of EL layers between the pair of electrodes. A light-emitting device with a tandem structure can realize a highly efficient light-emitting device without changing the amount of current.

[0153] The charge generation layer 106 has a function of injecting electrons into one EL layer (103a or 103b) and injecting holes into the other EL layer (103b or 103a) when a potential difference is generated between the first electrode 101 and the second electrode 102. Therefore, in FIG. 1B, when a voltage is applied to the first electrode 101 so that the potential is higher than that of the second electrode 102, electrons are injected from the charge generation layer 106 into the EL layer 103a and holes are injected into the EL layer 103b.

[0154] From the viewpoint of light extraction efficiency, the charge generation layer 106 is preferably transparent to visible light (specifically, the visible light transmittance of the charge generation layer 106 is 40% or more). The charge generation layer 106 functions even if it has a lower conductivity than the first electrode 101 and the second electrode 102.

[0155] FIG. 1C shows a laminated structure of the EL layer 103 in the light-emitting device. In this case, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. The EL layer 103 has a structure in which a hole injection layer 111, a hole transport layer 112, a light-emitting layer 113, an electron transport layer 114, and an electron injection layer 115 are laminated in this order on the first electrode 101. The first electrode 101 may be a cathode, and the second electrode 102 may be an anode. In this case, it is preferable to reverse the lamination order of the EL layer 103. Specifically, it is preferable to have a structure in which 111 on the first electrode 101, which is a cathode, is an electron injection layer, 112 is an electron transport layer, 113 is a light-emitting layer, 114 is a hole transport layer, and 115 is a hole injection layer.

[0156] The light-emitting layer 113 contains a light-emitting substance and a combination of a plurality of substances, and can have a structure that can obtain fluorescent or phosphorescent emission of a desired emission color. The light-emitting layer of the light-emitting device of one embodiment of the present invention preferably has the structure of the light-emitting layer described in Embodiment 1.

[0157] The light-emitting layer 113 may have a structure in which a plurality of light-emitting layers with different light-emitting colors are stacked. In the case of having a plurality of light-emitting layers, a structure in which different light-emitting materials are used for each light-emitting layer to exhibit different light-emitting colors (for example, white light emission obtained by combining light-emitting colors that are complementary to each other) can be used. For example, a structure in which a light-emitting layer containing a light-emitting material that emits red light, a light-emitting layer containing a light-emitting material that emits green light, and a light-emitting layer containing a light-emitting material that emits blue light are stacked, or a structure in which they are stacked with a layer having a carrier transporting material interposed therebetween. Alternatively, a combination of a light-emitting layer containing a light-emitting material that emits yellow light and a light-emitting layer containing a light-emitting material that emits blue light may be used. In this case, the light-emitting material and other materials used in each stacked light-emitting layer may be different from each other. Also, a structure in which different light-emitting colors are obtained from the plurality of EL layers (103a, 103b) shown in FIG. 1B may be used. In this case, the light-emitting material and other materials used in each light-emitting layer may be different from each other.

[0158] However, the stacked structure of the light-emitting layer 113 is not limited to the above. For example, the light-emitting layer 113 may have a structure in which a plurality of light-emitting layers emitting the same light-emitting color are stacked. For example, the light-emitting layer 113 may have a structure in which a first light-emitting layer containing a light-emitting substance that emits blue light and a second light-emitting layer containing a light-emitting substance that emits blue light are stacked, or a layer having a carrier transporting material is interposed between the first and second light-emitting layers. Alternatively, the same light-emitting color may be obtained from the plurality of EL layers (103a, 103b) shown in FIG. 1(B). In the case of a structure in which a plurality of light-emitting layers emitting the same light-emitting color are stacked, reliability may be improved more than in the case of a single layer structure.

[0159] When the light-emitting layer 113 has a structure in which a plurality of light-emitting layers are stacked, it is preferable that the structure of the light-emitting layer shown in Embodiment 1 be used for at least one of the plurality of light-emitting layers.

[0160] In addition, in a light-emitting device, for example, by making the first electrode 101 shown in FIG. 1(C) a reflective electrode and the second electrode 102 a semi-transmissive and semi-reflective electrode to have a micro-optical resonator (microcavity) structure, the light emitted from the light-emitting layer 113 included in the EL layer 103 can be resonated between both electrodes, and the light emitted from the second electrode 102 can be strengthened.

[0161] In addition, when the first electrode 101 of the light-emitting device is a reflective electrode having a laminated structure of a conductive material having reflectivity and a conductive material having light transmission (transparent conductive film), optical adjustment can be performed by controlling the film thickness of the transparent conductive film. Specifically, it is preferable to adjust the optical distance (product of film thickness and refractive index) between the first electrode 101 and the second electrode 102 to mλ / 2 (where m is an integer of 1 or more) or its vicinity, for the wavelength λ of light obtained from the light-emitting layer 113.

[0162] In order to amplify the desired light (wavelength: λ) obtained from the light-emitting layer 113, it is preferable to adjust the optical distance from the first electrode 101 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained and the optical distance from the second electrode 102 to the region (light-emitting region) in the light-emitting layer 113 where the desired light is obtained to (2m'+1)λ / 4 (where m' is an integer of 1 or more) or close thereto. Note that the light-emitting region referred to here refers to a recombination region of holes and electrons in the light-emitting layer 113.

[0163] By carrying out such optical adjustment, it is possible to narrow the spectrum of the specific monochromatic light obtained from the light-emitting layer 113, and to obtain light emission with excellent color purity.

[0164] However, in the above case, the optical distance between the first electrode 101 and the second electrode 102 can be strictly said to be the total thickness from the reflection area in the first electrode 101 to the reflection area in the second electrode 102. However, since it is difficult to strictly determine the reflection area in the first electrode 101 and the second electrode 102, it is assumed that the above-mentioned effect can be sufficiently obtained by assuming any position of the first electrode 101 and the second electrode 102 as the reflection area. Furthermore, the optical distance between the first electrode 101 and the light-emitting layer from which the desired light is obtained can be strictly said to be the optical distance between the reflection area in the first electrode 101 and the light-emitting area in the light-emitting layer from which the desired light is obtained. However, since it is difficult to strictly determine the reflection area in the first electrode 101 and the light-emitting area in the light-emitting layer from which the desired light is obtained, it is assumed that the above-mentioned effect can be sufficiently obtained by assuming any position of the first electrode 101 as the reflection area and any position of the light-emitting layer from which the desired light is obtained as the light-emitting area.

[0165] FIG. 1D shows a laminated structure of EL layers (103a, 103b) in a light-emitting device with a tandem structure. In this case, the first electrode 101 functions as an anode, and the second electrode 102 functions as a cathode. The EL layer 103a has a structure in which a hole injection layer 111a, a hole transport layer 112a, a light-emitting layer 113a, an electron transport layer 114a, and an electron injection layer 115a are laminated in this order on the first electrode 101. The EL layer 103b has a structure in which a hole injection layer 111b, a hole transport layer 112b, a light-emitting layer 113b, an electron transport layer 114b, and an electron injection layer 115b are laminated in this order on the charge generation layer 106. The first electrode 101 may be a cathode and the second electrode 102 may be an anode. In that case, it is preferable to reverse the lamination order of the EL layer 103.

[0166] For example, when the light-emitting device shown in Fig. 1(D) has a microcavity structure, the first electrode 101 is formed as a reflective electrode, and the second electrode 102 is formed as a semi-transmissive and semi-reflective electrode. Therefore, the electrode can be formed as a single layer or a multilayer using one or more desired electrode materials. The second electrode 102 is formed by selecting an appropriate material after the EL layer 103b is formed.

[0167] When the light-emitting device shown in FIG. 1(D) has a microcavity structure and light-emitting layers with different emission colors are used for each EL layer (103a, 103b), the microcavity structure allows light of a desired wavelength (monochromatic light) originating from any of the light-emitting layers to be extracted. By using such a light-emitting device in a light-emitting device and adjusting the microcavity structure so that light of a different wavelength can be extracted for each pixel, it becomes unnecessary to paint different colors (e.g., RGB) to obtain different emission colors for each pixel. Therefore, it is easy to achieve high definition. It can also be combined with a colored layer (color filter). Furthermore, it is possible to increase the emission intensity of a specific wavelength in the front direction, thereby reducing power consumption.

[0168] The light-emitting device shown in FIG. 1E is an example of the light-emitting device with the tandem structure shown in FIG. 1B, and has a structure in which three EL layers (103a, 103b, 103c) are stacked with charge generating layers (106a, 106b) sandwiched therebetween, as shown in the figure. The three EL layers (103a, 103b, 103c) each have a light-emitting layer (113a, 113b, 113c), and the light-emitting colors of the light-emitting layers can be freely combined. For example, the light-emitting layer 113a can be blue, the light-emitting layer 113b can be red, green, or yellow, and the light-emitting layer 113c can be blue, but it is also possible to make the light-emitting layer 113a red, the light-emitting layer 113b blue, green, or yellow, and the light-emitting layer 113c red.

[0169] In the light-emitting device according to one embodiment of the present invention described above, at least one of the first electrode 101 and the second electrode 102 is an electrode having translucency (such as a transparent electrode or a semi-transparent / semi-reflective electrode). When the electrode having translucency is a transparent electrode, the visible light transmittance of the transparent electrode is 40% or more. When the electrode is a semi-transparent / semi-reflective electrode, the visible light reflectance of the semi-transparent / semi-reflective electrode is 20% or more and 80% or less, preferably 40% or more and 70% or less. Furthermore, these electrodes have a resistivity of 1×10 -2 It is preferable to set it to Ωcm or less.

[0170] In the above-described light-emitting device according to one embodiment of the present invention, when one of the first electrode 101 and the second electrode 102 is a reflective electrode (reflective electrode), the electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%. -2 It is preferable to set it to Ωcm or less.

[0171] <Specific structure of light-emitting device> Next, a specific structure of the light-emitting device according to one embodiment of the present invention will be described with respect to the configuration of each layer. Note that in the description of each layer, reference numerals may be omitted for simplicity.

[0172] <First Electrode and Second Electrode> As the material for forming the first electrode and the second electrode, the following materials can be used in appropriate combination as long as the above-mentioned functions of both electrodes are satisfied. For example, metals, alloys, electrically conductive compounds, and mixtures thereof can be used appropriately. Specific examples include In-Sn oxide (also called ITO), In-Si-Sn oxide (also called ITSO), In-Zn oxide, and In-W-Zn oxide. In addition, metals such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), and neodymium (Nd), as well as alloys containing these in appropriate combinations, can also be used. Other examples that can be used include elements belonging to Group 1 or 2 of the periodic table (e.g., lithium (Li), cesium (Cs), calcium (Ca), and strontium (Sr)) that are not listed above, rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing appropriate combinations of these, as well as graphene.

[0173] 1(D), when the first electrode 101 is an anode, the hole injection layer 111a and the hole transport layer 112a of the EL layer 103a are successively laminated by vacuum deposition on the first electrode 101. After the EL layer 103a and the charge generation layer 106 are formed, the hole injection layer 111b and the hole transport layer 112b of the EL layer 103b are similarly successively laminated on the charge generation layer 106.

[0174] <Hole injection layer> The hole injection layer is a layer that injects holes from the first electrode, which is an anode, and the charge generation layer to the EL layer, and is a layer that contains an organic acceptor material and a material with high hole injection properties.

[0175] An organic acceptor material is a material that can generate holes in an organic compound by charge separation between the organic compound and another organic compound whose LUMO level and HOMO level are close to each other. Therefore, compounds having an electron-withdrawing group (halogen group or cyano group), such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives, can be used as organic acceptor materials. For example, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene)malononitrile, and the like can be used. Among organic acceptor materials, compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring having multiple heteroatoms, such as HAT-CN, are particularly suitable because they have high acceptability and stable film quality against heat. In addition, radialene derivatives having an electron-withdrawing group (especially a halogen group such as a fluoro group or a cyano group) [3] are also preferred because they have very high electron-accepting properties, and specifically, α,α',α''-1,2,3-cyclopropane triylidene tris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], α,α',α''-1,2,3-cyclopropane triylidene tris[2,3,4,5,6-pentafluorobenzeneacetonitrile], etc. can be used.

[0176] As a material with high hole injection properties, an oxide of a metal belonging to Groups 4 to 8 in the periodic table (such as transition metal oxides, such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide) can be used. Specific examples include molybdenum oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, tungsten oxide, manganese oxide, and rhenium oxide. Among the above, molybdenum oxide is preferred because it is stable in the air, has low hygroscopicity, and is easy to handle. In addition, phthalocyanine-based compounds such as phthalocyanine (abbreviation: HPc) or copper phthalocyanine (abbreviation: CuPc) can be used.

[0177] In addition to the above materials, the following low molecular weight compounds are also available: 4,4',4''-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis[4-bis(3-methylphenyl)aminophenyl]-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: DNTPD), 1,3,5-tris[N Aromatic amine compounds such as -(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), and 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) can be used.

[0178] Also, polymer compounds (oligomers, dendrimers, polymers, etc.) such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenylamino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide] (abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine] (abbreviation: Poly-TPD), etc. can be used. Alternatively, polymer compounds to which an acid has been added, such as poly(3,4-ethylenedioxythiophene) / polystyrenesulfonic acid (abbreviation: PEDOT / PSS), polyaniline / polystyrenesulfonic acid (abbreviation: PAni / PSS), etc. can also be used.

[0179] As the material with high hole injection properties, a mixed material containing a hole transport material and the above-mentioned organic acceptor material (electron accepting material) can also be used. In this case, electrons are extracted from the hole transport material by the organic acceptor material, generating holes in the hole injection layer 111, and the holes are injected into the light emitting layer 113 via the hole transport layer 112. The hole injection layer 111 may be formed as a single layer made of a mixed material containing a hole transport material and an organic acceptor material (electron accepting material), or may be formed by laminating the hole transport material and the organic acceptor material (electron accepting material) in separate layers.

[0180] In addition, the hole transport material has a hole mobility of 1×10 at a square root of the electric field strength [V / cm] of 600. -6 cm 2 A substance having a hole mobility of / Vs or more is preferable. Note that other substances can be used as long as they have a higher hole transporting property than an electron transporting property.

[0181] As the hole transporting material, a material having a high hole transporting property such as a compound having a π-electron-rich heteroaromatic ring (for example, a carbazole derivative, a furan derivative, or a thiophene derivative) and an aromatic amine (an organic compound having an aromatic amine skeleton) is preferable. The compound of the first embodiment has a hole transporting property, and therefore can also be used as the hole transporting material.

[0182] Examples of the carbazole derivative (organic compound having a carbazole ring) include bicarbazole derivatives (for example, 3,3'-bicarbazole derivatives) and aromatic amines having a carbazolyl group.

[0183] Specific examples of the bicarbazole derivative (e.g., 3,3'-bicarbazole derivative) include 3,3'-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (abbreviation: BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP).

[0184] Specific examples of the aromatic amine having a carbazolyl group include 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]bis(9,9-dimethyl-9H-fluoren-2-yl)amine (abbreviation: PCBFF), N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-(9,9-dimethyl-9H-fluoren-2-yl)-9,9-dimethyl-9H-fluoren-4 -amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-diphenyl-9H-fluoren-2-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-diphenyl-9H-fluoren-4-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi(9H-fluorene) -2-amine, N-(1,1'-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi(9H-fluoren)-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-2-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':4',1''-terphenyl-4-yl)-9,9-Dimethyl-9H-fluoren-2-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':3',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-(1,1':4',1''-terphenyl-4-yl)-9,9-dimethyl-9H-fluoren-4-amine, 4,4'-diphenyl-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl)-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N',N''-triphenyl-N,N',N''-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBASF), PCzPCA1, PC zPCA2, PCzPCN1, 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,Examples include 9'-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N'-bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), and 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA).

[0185] In addition to the above, examples of the carbazole derivative include 9-[4-(9-phenyl-9H-carbazol-3-yl)-phenyl]phenanthrene (abbreviation: PCPPn), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

[0186] Specific examples of the furan derivatives (organic compounds having a furan ring) include 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), and the like.

[0187] Specific examples of the thiophene derivatives (organic compounds having a thiophene ring) include 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV).

[0188] Specific examples of the aromatic amine include 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (abbreviation: TPD), N,N'-bis(9,9'-spirobi[9H-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: BPAFLP ... mBPAFLP, N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamine] No]spiro-9,9'-bifluorene (abbreviation: DPASF), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9'-bifluorene (abbreviation: DPA2SF), 4,4',4''-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1'-TNATA), TDATA, 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: m-MTDATA), N,N'-di(p-tolyl)-N,N'-diphenyl-p-phenylene Diamine (abbreviation: DTDPPA), DPAB, DNTPD, DPA3B, N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation Name: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4'-diphenyl-4''-(6;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB), 4,4'-diphenyl-4''-(7;1'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNβNB-03), 4,4'-diphenyl-4''-(7-phenyl)naphthalene 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-(6;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-(7;2'-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-(4;2'-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-(5;2'-binaphthyl-1-yl)triphenylamine ( Abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (Abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (Abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (Abbreviation: TPBiAβNBi), 4-phenyl-4'-(1-naphthyl)triphenylamine (Abbreviation: αNBA1BP), 4,4'-Bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4'-diphenyl-4''-[4'-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazol-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBi βNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H- fluoren-2-yl)-9,9'-spirobi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4'-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BP AFLBi), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirobi-9H-fluoren-1-amine, etc.

[0189] Other examples of the hole transport material that can be used include polymer compounds (oligomers, dendrimers, polymers, etc.) such as PVK, PVTPA, PTPDMA, Poly-TPD, etc. Alternatively, polymer compounds to which an acid has been added, such as PEDOT / PSS, PAni / PSS, etc., can also be used.

[0190] However, the hole transporting material is not limited to the above, and one or a combination of various known materials may be used as the hole transporting material.

[0191] The hole injection layer can be formed by using various known film formation methods, for example, by using a vacuum deposition method.

[0192] <Hole transport layer> The hole transport layer is a layer that transports holes injected from the first electrode to the light emitting layer by the hole injection layer. The hole transport layer is a layer containing a hole transport material. Therefore, the hole transport layer can be made of a hole transport material that can be used for the hole injection layer. The hole transport layer can function as a single layer, but may also have a laminated structure of two or more layers. For example, of the two hole transport layers, the layer in contact with the light emitting layer may also function as an electron block layer.

[0193] In the light-emitting device according to one embodiment of the present invention, the light-emitting layer can be formed using the same organic compound as that used for the hole-transport layer. It is more preferable to use the same organic compound for the hole-transport layer and the light-emitting layer because holes can be efficiently transported from the hole-transport layer to the light-emitting layer.

[0194] <Light-emitting layer> The light-emitting layer is a layer containing a light-emitting substance. As the light-emitting substance that can be used for the light-emitting layer, a substance that emits light of a color such as blue, purple, blue-purple, green, yellow-green, yellow, orange, or red can be appropriately used. Note that one light-emitting layer may have a stacked structure containing different light-emitting substances. It is preferable to use the structure of the light-emitting layer shown in the embodiment mode 1 for at least one light-emitting layer.

[0195] The light-emitting layer may contain one or more organic compounds (host materials, etc.) in addition to the light-emitting substance (guest material).

[0196] In addition, when a plurality of host materials are used in the light-emitting layer, it is preferable to use a substance having a larger energy gap than the existing guest material and the first host material as the second host material to be newly added. In addition, it is preferable that the lowest singlet excitation energy level (S1 level) of the second host material is higher than the S1 level of the first host material, and the lowest triplet excitation energy level (T1 level) of the second host material is higher than the T1 level of the guest material. In addition, it is preferable that the lowest triplet excitation energy level (T1 level) of the second host material is higher than the T1 level of the first host material. With such a configuration, an exciplex (also called an exciplex) can be formed by two types of host materials. In addition, in order to efficiently form an exciplex, it is particularly preferable to combine a compound that easily receives holes (hole transporting material) and a compound that easily receives electrons (electron transporting material). In addition, with this configuration, high efficiency, low voltage, and long life can be simultaneously achieved.

[0197] As the organic compound used as the host material (including the first host material and the second host material), as long as it satisfies the conditions as a host material used in the light-emitting layer, examples of the organic compound include a hole transporting material that can be used in the hole transporting layer described above, or an electron transporting material that can be used in the electron transporting layer described below, and may be an exciplex consisting of a plurality of organic compounds (the first host material and the second host material described above). Note that an exciplex that forms an excited state with a plurality of organic compounds has an extremely small difference between the S1 level and the T1 level, and functions as a TADF material that can convert triplet excitation energy into singlet excitation energy. In addition, as a combination of a plurality of organic compounds that form an exciplex, for example, one of them has a π-electron-deficient heteroaromatic ring, and the other has a π-electron-rich heteroaromatic ring. Note that as a combination that forms an exciplex, a phosphorescent material such as an iridium, rhodium, or platinum-based organometallic complex or a metal complex may be used on one side. The organic compound described in the first embodiment has an electron transporting property, and therefore can be effectively used as the first host material. In addition, since it has a hole transporting property, it can also be used as a second host material.

[0198] There is no particular limitation on the light-emitting substance that can be used in the light-emitting layer, and a light-emitting substance that converts singlet excitation energy into light emission in the visible light region, or a light-emitting substance that converts triplet excitation energy into light emission in the visible light region can be used.

[0199] <Light-emitting material that converts singlet excitation energy into light> Examples of luminescent materials that can be used in the luminescent layer and convert singlet excitation energy into luminescence include the following fluorescent substances (fluorescent luminescent materials). For example, pyrene derivatives, anthracene derivatives, triphenylene derivatives, fluorene derivatives, carbazole derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, dibenzoquinoxaline derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, phenanthrene derivatives, and naphthalene derivatives are listed. Pyrene derivatives are particularly preferred because of their high luminescence quantum yield. Specific examples of pyrene derivatives include N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'-bis(dibenzofuran-2-yl)-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N,N'-bis(dibenzothiophene-2-yl)-N, N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N'-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), N,N'-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), etc.

[0200] In addition, as luminescent materials that convert singlet excitation energy into luminescence, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: Name: YGA2S), 4-(9H-carbazol-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl -9-anthryl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), N,N''-(2-tert-butylanthracene-9,10-diyldi- 4,1-phenylene)bis(N,N',N'-triphenyl-1,4-phenylenediamine) (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), etc. can be used.

[0201] In addition, as luminescent materials that convert singlet excitation energy into luminescence, N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10- Bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), Coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), Rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4- 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N',N'-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB),6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 1,6BnfAP rn-03, 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10PCA2Nbf(IV)-02), 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b']bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02), etc. In particular, pyrene diamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, 1,6BnfAPrn-03, etc. can be used.

[0202] <Light-emitting material that converts triplet excitation energy into light> Next, examples of luminescent substances that can be used in the light-emitting layer 113 and that convert triplet excitation energy into luminescence include substances that emit phosphorescence (phosphorescent luminescent substances) and thermally activated delayed fluorescence (TADF) materials that exhibit thermally activated delayed fluorescence.

[0203] A phosphorescent material is a compound that exhibits phosphorescence but does not exhibit fluorescence in a temperature range from low temperature (e.g., 77 K) to room temperature (i.e., 77 K to 313 K). The phosphorescent material preferably has a metal element with a large spin-orbit interaction, and examples of the phosphorescent material include organometallic complexes, metal complexes (platinum complexes), and rare earth metal complexes. Specifically, transition metal elements are preferred, and platinum group elements (ruthenium (Ru), rhodium (Rh), Pd, osmium (Os), iridium (Ir), or Pt) are particularly preferred, and iridium is preferred because it can increase the transition probability involved in the direct transition between the singlet ground state and the triplet excited state.

[0204] <Phosphorescent material (450nm to 570nm: blue or green)> Examples of phosphorescent substances that exhibit blue or green light and have an emission spectrum with a peak wavelength of 450 nm or more and 570 nm or less include the following substances.

[0205] For example, tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl organometallic complexes having a 4H-triazole ring, such as tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPr5btz)3]), organometallic complexes with 1H-triazole rings, such as tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organometallic complexes with an imidazole ring, such as tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FIr6), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]iridium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinato-N,C 2’}Iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’] Examples include organometallic complexes with phenylpyridine derivatives having electron-withdrawing groups as ligands, such as iridium(III) acetylacetonate (abbreviation: FIr(acac)).

[0206] <Phosphorescent material (495nm to 590nm: green or yellow)> Examples of phosphorescent substances that exhibit green or yellow light and have an emission spectrum with a peak wavelength of 495 nm or more and 590 nm or less include the following substances.

[0207] For example, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm Organometallic iridium compounds having a pyrimidine ring, such as (acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]). iridium complexes with pyrazine rings, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinate)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinate)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]); tris(2-phenylpyrazinate-N,C 2’ ) Iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C 2’)iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-phenyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(4dppy)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl -κN)phenyl-κC], [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), {2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) Iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC] Organometallic iridium complexes with a pyridine ring, such as [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mdppy)), and bis(2,4-diphenyl-1,3-oxazolato-N,C 2’) Iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis{2-[4'-(perfluorophenyl)phenyl]pyridinato-N,C 2’}Iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), bis(2-phenylbenzothiazolato-N,C 2’ ) iridium(III) acetylacetonate (abbreviation: [Ir(bt)2(acac)]), as well as rare earth metal complexes such as tris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation: [Tb(acac)3(Phen)]).

[0208] <Phosphorescent material (570nm to 750nm: yellow or red)> Examples of phosphorescent substances that exhibit yellow or red light and have an emission spectrum with a peak wavelength of 570 nm or more and 750 nm or less include the following substances.

[0209] For example, pyrimidinate such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and (dipivaloylmethanato)bis[4,6-di(naphthalen-1-yl)pyrimidinato]iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]). Organometallic complexes containing an imidine ring, (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κN)phenyl-κC) 2O,O')iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ 2 O,O')iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), bis{2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]-4,6-dimethylphenyl-κC}(2,2',6,6'-tetramethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(dpm)]), (acetylacetonato)bis(2-methyl-3-phenylquinoxalinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(mpq)2(acac)), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C 2’ Organometallic complexes with pyrazine rings such as (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(dpq)2(acac)]), (acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]), tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), and bis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC] (2,4-pentanedionato-κ 2These include organometallic complexes with pyridine rings such as (O,O')iridium(III) (abbreviation: [Ir(dmpqn)2(acac)]), platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: [PtOEP]), and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]), and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]).

[0210] ≪TADF material≫ The following materials can be used as TADF materials. TADF materials are materials in which the difference between the S1 level and the T1 level is small (preferably 0.2 eV or less), the triplet excited state can be upconverted to the singlet excited state by a small amount of thermal energy (reverse intersystem crossing), and the material efficiently emits light (fluorescence) from the singlet excited state. Conditions for efficiently obtaining thermally activated delayed fluorescence include an energy difference between the triplet excited energy level and the singlet excited energy level of 0 eV or more and 0.2 eV or less, preferably 0 eV or more and 0.1 eV or less. The delayed fluorescence in TADF materials refers to light emission that has a spectrum similar to that of normal fluorescence, but has a significantly long lifespan. The lifespan is 1×10 -6 seconds or 1×10 -3 seconds or more. In addition, the organic compound described in the first embodiment can be used.

[0211] The TADF material can also be used as an electron transporting material, a hole transporting material, or a host material.

[0212] Examples of TADF materials include fullerene and its derivatives, acridine derivatives such as proflavine, eosin, etc. Also included are metal-containing porphyrins including magnesium (Mg), Zn, cadmium (Cd), Sn, Pt, In, or Pd. Examples of metal-containing porphyrins include protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).

[0213] [ka]

[0214] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxy) 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9, 9-Dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthracene]-10'-one (abbreviation: ACRSA), 4-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9'-phenyl-3,3'- Heteroaromatic compounds having a π-electron rich heteroaromatic compound and a π-electron deficient heteroaromatic compound, such as 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), may also be used.

[0215] In addition, a substance in which a π-electron rich heteroaromatic compound and a π-electron deficient heteroaromatic compound are directly bonded is particularly preferable because the donor property of the π-electron rich heteroaromatic compound and the acceptor property of the π-electron deficient heteroaromatic compound are both strong, and the energy difference between the singlet excited state and the triplet excited state is small. In addition, a TADF material (TADF100) in which the singlet excited state and the triplet excited state are in thermal equilibrium may be used as the TADF material. Such a TADF material has a short emission lifetime (excitation lifetime), and therefore it is possible to suppress a decrease in efficiency in a high brightness region of a light-emitting element.

[0216] [ka]

[0217] In addition to the above, examples of materials capable of converting triplet excitation energy into luminescence include nanostructures of transition metal compounds having a perovskite structure. In particular, nanostructures of metal halide perovskites are preferred. As the nanostructures, nanoparticles and nanorods are preferred.

[0218] In the light-emitting layer, as an organic compound (such as a host material) used in combination with the above-mentioned light-emitting substance (guest material), one or more substances having an energy gap larger than the energy gap of the light-emitting substance (guest material) may be selected and used.

[0219] <Fluorescent host material> When the light-emitting substance used in the light-emitting layer is a fluorescent light-emitting substance, it is preferable to use an organic compound (host material) to be combined with the light-emitting layer that has a high energy level in the singlet excited state and a low energy level in the triplet excited state, or an organic compound with a high fluorescence quantum yield. Therefore, as long as the organic compound satisfies such conditions, the hole-transporting material (described above) and the electron-transporting material (described below) shown in this embodiment mode can be used. In addition, the organic compound described in the embodiment mode 1 can be used.

[0220] Although some of the examples overlap with those described above, examples of the organic compound (host material) from the viewpoint of a preferable combination with a light-emitting substance (fluorescent light-emitting substance) include condensed polycyclic aromatic compounds such as anthracene derivatives, tetracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo[g,p]chrysene derivatives.

[0221] Specific examples of organic compounds (host materials) that are preferably used in combination with fluorescent substances include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), PCPN, 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N' ,N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), CzPA, 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-[4'-(9-phenyl-9H-fluoren-9-yl)biphenyl -4-yl]anthracene (abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl)anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,β-ADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNPAnth), 2,9-di(1-naphthyl)-10-phenylanthracene (abbreviation: 2αN-αNPhA), 9-(1-naphthyl)-10-[3-(1-naphthyl)phenyl]anthracene (abbreviation: αN-mαNPAnth), 9-(2-naphthyl)-10-[3-(1-naphthyl)phenyl]anthracene (abbreviation: βN-mαNPAnth), 9-(1-naphthyl)-10-[4-(1-naphthyl)phenyl]anthracene (abbreviation: αN-αNPAnth), 9-(2-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: βN-βNPAnth), 2-(1-naphthyl)-9- (2-naphthyl)-10-phenylanthracene (abbreviation: 2αN-βNPhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthracenyl]phenyl}-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), 9,9'-biphenyl tolyl (abbreviation: BANT), 9,9'-(stilbene-3,3'-diyl)diphenanthrene (abbreviation: DPNS), 9,9'-(stilbene-4,4'-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene, 5,12-bis(biphenyl-2-yl)tetracene, etc.

[0222] <Phosphorescent host material> In addition, when the light-emitting substance used in the light-emitting layer is a phosphorescent light-emitting substance, an organic compound having a triplet excitation energy larger than the triplet excitation energy (energy difference between the ground state and the triplet excited state) of the light-emitting substance may be selected as the organic compound (host material) to be combined. In addition, when a plurality of organic compounds (for example, a first host material and a second host material (or assist material)) are used in combination with the light-emitting substance to form an exciplex, it is preferable to mix these plurality of organic compounds with the phosphorescent light-emitting substance. In addition, the organic compounds described in the embodiment 1 can be used.

[0223] With this structure, it is possible to efficiently obtain light emission using ExTET (Exciplex-Triplet Energy Transfer), which is an energy transfer from an exciplex to a light-emitting substance. As a combination of multiple organic compounds, it is preferable to use one that easily forms an exciplex, and it is particularly preferable to combine a compound that easily receives holes (hole transport material) with a compound that easily receives electrons (electron transport material).

[0224] Although some of the organic compounds (host materials, assist materials) may be used in combination with the light-emitting substance (phosphorescent light-emitting substance), examples of the organic compounds include aromatic amines (organic compounds having an aromatic amine skeleton), carbazole derivatives (organic compounds having a carbazole ring), dibenzothiophene derivatives (organic compounds having a dibenzothiophene ring), dibenzofuran derivatives (organic compounds having a dibenzofuran ring), oxadiazole derivatives (organic compounds having an oxadiazole ring), triazole derivatives (organic compounds having a triazole ring), benzimidazole derivatives (benzoin), and the like. midazole ring), quinoxaline derivatives (organic compounds having a quinoxaline ring), dibenzoquinoxaline derivatives (organic compounds having a dibenzoquinoxaline ring), pyrimidine derivatives (organic compounds having a pyrimidine ring), triazine derivatives (organic compounds having a triazine ring), pyridine derivatives (organic compounds having a pyridine ring), bipyridine derivatives (organic compounds having a bipyridine ring), phenanthroline derivatives (organic compounds having a phenanthroline ring), phlodiazine derivatives (organic compounds having a phlodiazine ring), zinc- and aluminum-based metal complexes, and the like.

[0225] Among the organic compounds, specific examples of the aromatic amine and carbazole derivative, which are organic compounds having a high hole-transporting property, are the same as the specific examples of the hole-transporting material described above, and any of these are preferable as the host material.

[0226] Among the above organic compounds, specific examples of dibenzothiophene derivatives and dibenzofuran derivatives, which are organic compounds with high hole-transporting properties, include mmDBFFLBi-II, DBF3P-II, DBT3P-II, DBTFLP-III, DBTFLP-IV, 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II), and the like, all of which are preferable as host materials.

[0227] Other examples of preferred host materials include metal complexes having oxazole- or thiazole-based ligands, such as bis[2-(2-benzoxazolyl)phenolate]zinc(II) (abbreviation: ZnPBO) and bis[2-(2-benzothiazolyl)phenolate]zinc(II) (abbreviation: ZnBTZ).

[0228] Specific examples of the organic compounds having high electron transport properties among the above organic compounds include oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, quinazoline derivatives, and phenanthroline derivatives. These include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II) ), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), and other heteroaromatic rings with a polyazole ring; bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalene-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), and other heteroaromatic rings with a pyridine ring Organic compounds, 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), and 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-{4-[9,10-di(2-naphthyl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN), 2-[4'-(9-phenyl-9H-carbazol-3-yl)-3,1'-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), etc., all of which are preferred as host materials.

[0229] Among the above organic compounds, specific examples of organic compounds with high electron transport properties, such as pyridine derivatives, diazine derivatives (including pyrimidine derivatives, pyrazine derivatives, and pyridazine derivatives), triazine derivatives, and furodiazine derivatives, include 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), and 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II). ,6mCzP2Pm), PCCzPTzn, mPCCzPTzn-02, 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 2-[3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3 ,5-triazine (abbreviation: mFBPTzn), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 11-[(3'-dibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr), 11-[(3'-dibenzothiophen-4-yl)biphenyl-4-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine, 11-[3'-(9H-carbazol-9-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furo[2,3-b]pyrazine, 12-(9'-phenyl-3,3'-Bi-9H-carbazol-9-yl)phenanthro[9',10':4,5]furo[2,3-b]pyrazine (abbreviation: 12PCCzPnfpr), 9-[(3'-9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9pmPCBPNfpr), 9-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9PCCzNfpr), 10-(9'-phenyl-3,3'-bi H-carbazol-9-yl)naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 10PCCzNfpr), 9-[3'-(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mBnfBPNfpr), 9-{3-[6-(9,9-dimethylfluoren-2-yl)dibenzothiophen-4-yl]phenyl}naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mFDBtPNfpr), 9-[3'- (6-phenyldibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr-02), 9-[3-(9'-phenyl-3,3'-bi-9H-carbazol-9-yl)phenyl]naphtho[1',2':4,5]furo[2,3-b]pyrazine (abbreviation: 9mPCCzPNfpr), 9-{(3'-[2,8-diphenyldibenzothiophen-4-yl]biphenyl-3-yl}naphtho[1',2':4,5]furo[2,3-b]pyrazine, 11-{(3'-[2, 8-diphenyldibenzothiophen-4-yl]biphenyl-3-yl}phenanthro[9',10':4,5]furo[2,3-b]pyrazine, 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3'-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-Spirobi[9H-fluoren]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-{8-[(1,1':4',1''-terphenyl)-4-yl] -1-dibenzofuranyl}-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), and other organic compounds containing heteroaromatic rings having a diazine ring, all of which are preferred as host materials.

[0230] Among the above organic compounds, specific examples of metal complexes, which are organic compounds with high electron transport properties, include zinc- or aluminum-based metal complexes such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq), as well as metal complexes having a quinoline ring or a benzoquinoline ring, all of which are preferable as the host material.

[0231] Other preferred host materials include polymer compounds such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), and poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6'-diyl)] (abbreviation: PF-BPy).

[0232] Furthermore, organic compounds having a diazine ring, such as bipolar 9-phenyl-9'-(4-phenyl-2-quinazolinyl)-3,3'-bi-9H-carbazole (abbreviation: PCCzQz), 2mpPCBPDBq, mINc(II)PTzn, 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), and 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz), which are organic compounds having high hole transporting and electron transporting properties, can also be used as the host material.

[0233] <Electron transport layer> The electron transport layer is a layer that transports electrons injected from the second electrode and the charge generation layer by the electron injection layer described later to the light emitting layer. The material used for the electron transport layer has an electron mobility of 1×10 at a square root of an electric field strength [V / cm] of 600 or more. -6 cm 2A substance having an electron mobility of 100 / Vs or more is preferable. Note that other substances can be used as long as they have a higher transportability of electrons than holes. The electron transport layer can function as a single layer, but may have a laminated structure of two or more layers. For example, of the two electron transport layers, the layer in contact with the light-emitting layer may also function as a hole blocking layer. In addition, the electron transport layer may have a laminated structure to improve heat resistance in some cases. Note that the above mixed material has heat resistance, so that the effect of a thermal process on device characteristics can be suppressed by performing a photolithography process on the electron transport layer using this material.

[0234] ≪Electron transport material≫ As the electron transporting material that can be used in the electron transport layer, an organic compound with high electron transporting properties can be used, for example, a heteroaromatic compound can be used. The heteroaromatic compound is a cyclic compound containing at least two different elements in a ring. The ring structure includes a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, etc., and a five-membered ring or a six-membered ring is particularly preferred, and the element contained is preferably a heteroaromatic compound containing one or more of nitrogen, oxygen, or sulfur in addition to carbon. In particular, a heteroaromatic compound containing nitrogen (nitrogen-containing heteroaromatic compound) is preferred, and it is preferable to use a material with high electron transporting properties (electron transporting material) such as a nitrogen-containing heteroaromatic compound or a π-electron-deficient heteroaromatic compound containing the same. The compound of the first embodiment has electron transporting properties, and can be used as an electron transporting material.

[0235] The electron transport material may be a material different from the material used in the light-emitting layer. Not all of the excitons generated by the recombination of carriers in the light-emitting layer can contribute to light emission, and they may diffuse to a layer adjacent to or located near the light-emitting layer. In order to avoid this phenomenon, it is preferable that the energy level (lowest singlet excitation energy level or lowest triplet excitation energy level) of the material used in the layer adjacent to or located near the light-emitting layer is higher than that of the material used in the light-emitting layer. Therefore, by using a material different from the material used in the light-emitting layer as the electron transport material, a highly efficient element can be obtained.

[0236] A heteroaromatic compound is an organic compound that contains at least one heteroaromatic ring.

[0237] The heteroaromatic ring has any one of a pyridine ring, a diazine ring, a triazine ring, a polyazole ring, an oxazole ring, and a thiazole ring. The heteroaromatic ring having a diazine ring includes a heteroaromatic ring having a pyrimidine ring, a pyrazine ring, and a pyridazine ring. The heteroaromatic ring having a polyazole ring includes a heteroaromatic ring having an imidazole ring, a triazole ring, and an oxadiazole ring.

[0238] The heteroaromatic ring also includes a condensed heteroaromatic ring having a condensed ring structure, such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a phlodiazine ring, or a benzimidazole ring.

[0239] Incidentally, among heteroaromatic compounds containing one or more of nitrogen, oxygen, and sulfur in addition to carbon, examples of heteroaromatic compounds having a five-membered ring structure include heteroaromatic compounds having an imidazole ring, heteroaromatic compounds having a triazole ring, heteroaromatic compounds having an oxazole ring, heteroaromatic compounds having an oxadiazole ring, heteroaromatic compounds having a thiazole ring, and heteroaromatic compounds having a benzimidazole ring.

[0240] Furthermore, for example, among heteroaromatic compounds containing one or more of nitrogen, oxygen, and sulfur in addition to carbon, examples of heteroaromatic compounds having a 6-membered ring structure include heteroaromatic compounds having a heteroaromatic ring such as a pyridine ring, a diazine ring (including a pyrimidine ring, a pyrazine ring, and a pyridazine ring), and a triazine ring. Included in the heteroaromatic compounds having a structure in which pyridine rings are linked are heteroaromatic compounds having a bipyridine structure and heteroaromatic compounds having a terpyridine structure.

[0241] Further, examples of heteroaromatic compounds having a fused ring structure partially including the above-mentioned 6-membered ring structure include heteroaromatic compounds having a fused heteroaromatic ring such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a phlodiazine ring (including a structure in which an aromatic ring is fused to the furan ring of a phlodiazine ring), and a benzimidazole ring.

[0242] Specific examples of the heteroaromatic compound having a five-membered ring structure (polyazole ring (including imidazole ring, triazole ring, and oxadiazole ring), oxazole ring, thiazole ring, benzimidazole ring, etc.) include PBD, OXD-7, CO11, TAZ, 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), TPBI, mDBTBIm-II, and BzOS.

[0243] Specific examples of the heteroaromatic compound having a 6-membered ring structure (including a heteroaromatic ring having a pyridine ring, a diazine ring, a triazine ring, etc.) include heteroaromatic compounds having a pyridine ring such as 35DCzPPy and TmPyPB, PCCzPTzn, mPCCzPTzn-02, mINc(II)PTzn, mTpBPTzn, BP-SFTzn, 2,4NP-6PyPPm, PCDBfTzn, mBP-TPDBfTzn, 2-{3-[3-(dibenzothiophene Heteroaromatic compounds containing heteroaromatic rings with triazine rings such as {DBtBPTzn} and {FBPTzn}, 4,6mPnP2Pm, 4,6mDBTP2Pm-II, 4,6mCzP2Pm, 4,6mCzBP2Pm, 6mBP-4Cz2PPm, 6BP-4Cz2PPm, 8-(naphthalene-2-yl)-4-[3-(dibenzothiophene-4-yl)phenyl]-[1]benzo ... 8βN-4mDBtPBfpm, 8BP-4mDBtPBfpm, 9mDBtBPNfpr, 9pmDBtBPNfpr, 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8- and heteroaromatic compounds containing a heteroaromatic ring having a diazine (pyrimidine) ring, such as [3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm) and 8-[(2,2'-binaphthalene)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm). The aromatic compounds containing a heteroaromatic ring include heteroaromatic compounds having a condensed heteroaromatic ring.

[0244] In addition, there are also compounds having a diazine (pyrimidine) ring, such as 2,2'-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(2,2'-bipyridine-6,6'-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6'(P-Bqn)2BPy), 2,2'-(pyridine-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), and 6mBP-4Cz2PPm. Examples of the heteroaromatic compounds include heteroaromatic compounds containing a heteroaromatic ring having a triazine ring, such as 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz), and 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthryl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn).

[0245] Specific examples of the above-mentioned heteroaromatic compounds having a fused ring structure partially including a 6-membered ring structure (heteroaromatic compounds having a fused ring structure) include heteroaromatic compounds having a quinoxaline ring such as BPhen, bathocuproine (abbreviation: BCP), NBPhen, mPPhen2P, 2,6(P-Bqn)2Py, 2mDBTPDBq-II, 2mDBTBPDBq-II, 2mCzBPDBq, 2CzPDBq-III, 7mDBTPDBq-II, and 6mDBTPDBq-II and 2mpPCBPDBq.

[0246] In addition to the heteroaromatic compounds described above, the electron transport layer may include the following metal complexes: metal complexes having a quinoline ring or a benzoquinoline ring, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq3), Almq3, 8-quinolinolato-lithium (abbreviation: Liq), BeBq2, BAlq, and Znq, and metal complexes having an oxazole ring or a thiazole ring, such as ZnPBO and ZnBTZ.

[0247] Moreover, polymer compounds such as PPy, PF-Py, and PF-BPy can also be used as the electron transporting material.

[0248] <Electron injection layer> The electron injection layer is a layer containing a substance with high electron injection properties. The electron injection layer is a layer for increasing the efficiency of electron injection from the second electrode, and it is preferable to use a material with a small difference (0.5 eV or less) between the work function value of the material used for the second electrode and the LUMO level value of the material used for the electron injection layer. Therefore, the electron injection layer may be made of lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), Liq, 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiO x ), alkaline metals such as cesium carbonate, alkaline earth metals, or compounds thereof can be used. Also, rare earth metals such as Yb, or rare earth metal compounds such as erbium fluoride (ErF3) can be used. The electron injection layer may be formed by mixing a plurality of the above materials, or may be formed by stacking a plurality of the above materials. For example, the electron injection layer may be a stack of layers having different electrical resistances. Also, an electride may be used for the electron injection layer. For example, an electride may be a substance in which a high concentration of electrons is added to a mixed oxide of calcium and aluminum. The above-mentioned substance constituting the electron transport layer can also be used.

[0249] In addition, a mixed material obtained by mixing an organic compound and an electron donor (donor) may be used for the electron injection layer. Such a mixed material has excellent electron injection and electron transport properties because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material that is excellent in transporting the generated electrons, and specifically, for example, the above-mentioned electron transport material (metal complex, heteroaromatic compound, etc.) used for the electron transport layer can be used. As the electron donor, any substance that exhibits electron donating properties to the organic compound may be used. Specifically, alkali metals, alkaline earth metals, and rare earth metals are preferred, and examples thereof include Li, Cs, Mg, Ca, erbium (Er), and Yb. In addition, alkali metal oxides and alkaline earth metal oxides are preferred, and examples thereof include lithium oxide, calcium oxide, and barium oxide. In addition, a Lewis base such as magnesium oxide can also be used. In addition, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can also be used. In addition, a plurality of these materials may be used in a laminated form.

[0250] Alternatively, the electron injection layer may be made of a mixed material obtained by mixing an organic compound and a metal. The organic compound used here preferably has a LUMO level of -3.6 eV or more and -2.3 eV or less. In addition, a material having an unshared electron pair is preferable.

[0251] Therefore, as the organic compound used in the above mixed material, a mixed material obtained by mixing a heteroaromatic compound with a metal, which is described above as being usable in the electron transport layer, may be used. As the heteroaromatic compound, a material having an unshared electron pair, such as a heteroaromatic compound having a 5-membered ring structure (imidazole ring, triazole ring, oxazole ring, oxadiazole ring, thiazole ring, benzimidazole ring, etc.), a heteroaromatic compound having a 6-membered ring structure (pyridine ring, diazine ring (including pyrimidine ring, pyrazine ring, pyridazine ring, etc.), triazine ring, bipyridine ring, terpyridine ring, etc.), or a heteroaromatic compound having a condensed ring structure (quinoline ring, benzoquinoline ring, quinoxaline ring, dibenzoquinoxaline ring, phenanthroline ring, etc.) that partially includes a 6-membered ring structure, is preferable. Specific materials have been described above, so a description thereof will be omitted here.

[0252] As the metal used in the above mixed material, it is preferable to use a transition metal belonging to Group 5, Group 7, Group 9 or Group 11 in the periodic table and a material belonging to Group 13, such as Ag, Cu, Al, or In. In this case, the organic compound forms a half occupied molecular orbital (SOMO) with the transition metal.

[0253] 1D, for example, when the light obtained from the light-emitting layer 113b is amplified, the optical distance between the second electrode 102 and the light-emitting layer 113b is preferably less than ¼ of the wavelength λ of the light emitted by the light-emitting layer 113b. In this case, the optical distance can be adjusted by changing the thickness of the electron-transporting layer 114b or the electron-injecting layer 115b.

[0254] <Charge generation layer> The charge generation layer has a function of injecting electrons into one EL layer and injecting holes into the other EL layer when a voltage is applied between the first electrode and the second electrode in a light-emitting device with a tandem structure. The charge generation layer may be a structure in which an electron acceptor is added to a hole transporting material (also called a P-type layer), or a structure in which an electron donor is added to an electron transporting material (also called an electron injection buffer layer). In addition, both of these structures may be stacked. Furthermore, an electron relay layer may be provided between the P-type layer and the electron injection buffer layer. By forming the charge generation layer using the above-mentioned material, it is possible to suppress an increase in driving voltage when EL layers are stacked.

[0255] In the case where the charge generation layer has a structure in which an electron acceptor is added to a hole transporting material that is an organic compound (P-type layer), the material shown in this embodiment mode can be used as the hole transporting material. Examples of the electron acceptor include F4-TCNQ, chloranil, and the like. Examples of the metal oxide that belongs to Groups 4 to 8 of the periodic table include oxides of metals. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide can be used. Note that the above-mentioned acceptor material may be used. In addition, a mixed film obtained by mixing materials constituting the P-type layer may be used, or single films containing each material may be stacked.

[0256] In the case where the charge generation layer has a structure in which an electron donor is added to an electron transporting material (electron injection buffer layer), the material shown in this embodiment can be used as the electron transporting material. In addition, as the electron donor, an alkali metal, an alkaline earth metal, a rare earth metal, or a metal belonging to Group 2 or Group 13 in the periodic table, and an oxide or carbonate thereof can be used. Specifically, it is preferable to use Li, Cs, Mg, calcium (Ca), Yb, In, lithium oxide (Li2O), cesium carbonate, or the like. In addition, an organic compound such as tetrathianaphthacene may be used as the electron donor.

[0257] In the case where an electron relay layer is provided between the P-type layer and the electron injection buffer layer in the charge generation layer, the electron relay layer contains at least a substance having electron transport properties, and has a function of preventing interaction between the electron injection buffer layer and the P-type layer and smoothly transferring electrons. The LUMO level of the substance having electron transport properties contained in the electron relay layer is preferably between the LUMO level of the acceptor substance in the P-type layer and the LUMO level of the substance having electron transport properties contained in the electron transport layer in contact with the charge generation layer. The specific energy level of the LUMO level of the substance having electron transport properties used in the electron relay layer is -5.0 eV or more, preferably -5.0 eV or more and -3.0 eV or less. It is preferable to use a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand as the substance having electron transport properties used in the electron relay layer.

[0258] <Cap layer> Although not shown in FIGS. 1A to 1E, a capping layer may be provided on the second electrode 102 of the light-emitting device. For example, a material with a high refractive index can be used for the capping layer. By providing the capping layer on the second electrode 102, the extraction efficiency of light emitted from the second electrode 102 can be improved.

[0259] Specific examples of materials that can be used for the cap layer include 5,5'-diphenyl-2,2'-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviation: BisBTc), DBT3P-II, etc. In addition, the organic compounds described in the first embodiment can be used.

[0260] <Substrate> The light-emitting device shown in this embodiment mode can be formed on various substrates. The type of substrate is not limited to a specific one. Examples of the substrate include a semiconductor substrate (e.g., a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate having stainless steel foil, a tungsten substrate, a substrate having tungsten foil, a flexible substrate, a laminated film, a paper containing a fibrous material, or a base film.

[0261] Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, soda lime glass, etc. Examples of flexible substrates, laminated films, base films, etc. include plastics such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethersulfone (PES), synthetic resins such as acrylic resins, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyamide, polyimide, aramid, epoxy resins, inorganic deposition films, and papers.

[0262] In addition, a gas phase method such as a vapor deposition method, a spin coating method, and a liquid phase method such as an inkjet method can be used to manufacture the light-emitting device shown in this embodiment. When a vapor deposition method is used, a physical vapor deposition method (PVD method) such as a sputtering method, an ion plating method, an ion beam deposition method, a molecular beam deposition method, and a vacuum deposition method, a chemical vapor deposition method (CVD method), and the like can be used. In particular, layers having various functions included in the EL layer of the light-emitting device (hole injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, and electron injection layer 115) can be formed by a vapor deposition method (vacuum deposition method, etc.), a coating method (dip coating method, die coating method, bar coating method, spin coating method, spray coating method, and the like), a printing method (inkjet method, screen (screen printing) method, offset (lithographic printing) method, flexo (relief printing) method, gravure method, microcontact method, and the like), and the like.

[0263] In addition, when applying a film formation method such as the coating method or printing method, it is possible to use a high molecular compound (oligomer, dendrimer, polymer, etc.), a medium molecular compound (a compound in the intermediate range between a low molecular weight and a high molecular weight: a molecular weight of 400 to 4000), an inorganic compound (quantum dot material, etc.), etc. In addition, as the quantum dot material, it is possible to use a colloidal quantum dot material, an alloy type quantum dot material, a core-shell type quantum dot material, a core type quantum dot material, etc.

[0264] The layers constituting the EL layer 103 of the light-emitting device described in this embodiment (hole injection layer 111, hole transport layer 112, light-emitting layer 113, electron transport layer 114, and electron injection layer 115) are not limited to the materials described in this embodiment, and other materials can be used in combination as long as they fulfill the functions of each layer.

[0265] In this specification and the like, the terms "layer" and "film" can be used interchangeably as appropriate.

[0266] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0267] (Embodiment 3) In this embodiment, a light receiving and emitting device 700 will be described in order to explain a specific configuration example of a light emitting device according to one embodiment of the present invention and an example of a manufacturing method thereof. The light receiving and emitting device 700 is a device having both a light emitting device and a light receiving device, and can also be called a light emitting device including a light receiving device or a light receiving device including a light emitting device. The light receiving and emitting device 700 can also be called a display panel or a display device because it can be applied to a display unit of an electronic device or the like.

[0268] <Configuration Example of Light Receiving and Emitting Device 700> The light receiving and emitting device 700 shown in FIG. 2(A) has a light emitting device 550B, a light emitting device 550G, a light emitting device 550R, and a light receiving device 550PS formed on a functional layer 520 provided on a first substrate 510. The functional layer 520 includes a driving circuit such as a gate driver and a source driver composed of a plurality of transistors, as well as wiring and the like that electrically connects them. These driving circuits are, for example, electrically connected to the light emitting device 550B, the light emitting device 550G, the light emitting device 550R, and the light receiving device 550PS, respectively, and can drive them. The light receiving and emitting device 700 also includes an insulating layer 705 on the functional layer 520 and each device (the light emitting device and the light receiving device), and the insulating layer 705 has a function of bonding the second substrate 770 and the functional layer 520 together.

[0269] Light-emitting device 550B, light-emitting device 550G, and light-emitting device 550R have the device structure described in Embodiment 2. The light-emitting devices have different configurations of EL layers 103 (see FIG. 1(A)). For example, light-emitting layer 105B of EL layer 103B can emit blue light, light-emitting layer 105G of EL layer 103G can emit green light, and light-emitting layer 105R of EL layer 103R can emit red light.

[0270] In this embodiment, the case where each device (plurality of light-emitting devices and light-receiving devices) is formed separately will be described, but a part of the EL layer of the light-emitting device (hole injection layer, hole transport layer, and electron transport layer) and a part of the active layer of the light-receiving device (hole injection layer, hole transport layer, and electron transport layer) may be simultaneously formed of the same material in the manufacturing process. This will be described in detail in embodiment 8.

[0271] In this specification and the like, a structure in which the light-emitting layers of the light-emitting devices of each color (e.g., blue (B), green (G), and red (R)) and the light-receiving layers of the light-receiving devices are separately manufactured or separately painted may be referred to as a side-by-side (SBS) structure. In the light-receiving and light-emitting device 700 shown in FIG. 2A, the light-emitting device 550B, the light-emitting device 550G, the light-emitting device 550R, and the light-receiving device 550PS are arranged in this order, but one embodiment of the present invention is not limited to this configuration.

[0272] In FIG. 2A, the light-emitting device 550B has an electrode 551B, an electrode 552, and an EL layer 103B sandwiched between the electrodes 551B and 552. The light-emitting device 550G has an electrode 551G, an electrode 552, and an EL layer 103G sandwiched between the electrodes 551G and 552. The light-emitting device 550R has an electrode 551R, an electrode 552, and an EL layer 103R sandwiched between the electrodes 551R and 552. The EL layers (103B, 103G, 103R) have a stacked structure including a plurality of layers with different functions including light-emitting layers (105B, 105G, 105R). The specific configuration of each layer of the light-emitting device is as shown in the second embodiment.

[0273] 2A, light-receiving device 550PS has electrode 551PS, electrode 552, and light-receiving layer 103PS sandwiched between electrode 551PS and electrode 552. Light-receiving layer 103PS has a layered structure including a plurality of layers with different functions, including active layer 105PS. The specific configuration of the light-receiving device is as shown in embodiment 8.

[0274] FIG. 2(A) illustrates a case in which the EL layer 103B has a hole injection / transport layer 104B, an emitting layer 105B, an electron transport layer 108B, and an electron injection layer 109, the EL layer 103G has a hole injection / transport layer 104G, an emitting layer 105G, an electron transport layer 108G, and an electron injection layer 109, the EL layer 103R has a hole injection / transport layer 104R, an emitting layer 105R, an electron transport layer 108R, and an electron injection layer 109, and the light receiving layer 103PS has a hole injection / transport layer 104PS, an active layer 105PS, an electron transport layer 108PS, and an electron injection layer 109, but the present invention is not limited to this.

[0275] In FIG. 2A, electron injection layer 109 and electrode 552 are layers (common layers) common to each device (light-emitting device 550B, light-emitting device 550G, light-emitting device 550R, and light-receiving device 550PS).

[0276] Hereinafter, for the sake of simplicity, light-emitting device 550B, light-emitting device 550G, and light-emitting device 550R may be collectively referred to as light-emitting device 550, electrode 551B, electrode 551G, and electrode 551R may be collectively referred to as electrode 551, EL layer 103B, EL layer 103G, and EL layer 103R may be collectively referred to as EL layer 103, hole injection / transport layer 104B, hole injection / transport layer 104G, and hole injection / transport layer 104R may be collectively referred to as hole injection / transport layer 104, light-emitting layer 105B, light-emitting layer 105G, and light-emitting layer 105R may be collectively referred to as light-emitting layer 105, and electron transport layer 108B, electron transport layer 108G, and electron transport layer 108R may be collectively referred to as electron transport layer 108.

[0277] As shown in FIG. 2(A), an insulating layer 107 may be formed on the side surfaces (or ends) of the hole injection / transport layer 104, the light emitting layer 105, and the electron transport layer 108 of the EL layer 103, and on the side surfaces (or ends) of the hole injection / transport layer 104PS, the active layer 105PS, and the electron transport layer 108PS of the light receiving layer 103PS. The insulating layer 107 is formed in contact with the side surfaces (or ends) of the EL layer 103 and the light receiving layer 103PS. This makes it possible to suppress the intrusion of oxygen, moisture, or their constituent elements from the side surfaces of the EL layer 103 and the light receiving layer 103PS into the inside. The insulating layer 107 has a structure that continuously covers the side surfaces of a part of the EL layer 103 of the adjacent light emitting device, or a part of the light receiving layer 103PS of the light receiving device. For example, in FIG. 2A, the sides of a portion of EL layer 103B of light-emitting device 550B and a portion of EL layer 103G of light-emitting device 550G are covered by continuous insulating layer 107.

[0278] 2(A), a partition 528 is provided between each of the devices. However, the electron injection layer 109 and the electrode 552, which are common layers of each device, are not divided by the partition 528 but are provided continuously. Therefore, it can be said that the partition 528 is provided in a region surrounded by the electron injection layer 109 and the insulating layer 107. The partition 528 is located on the side (or end) of the electrode 551, part of the EL layer 103 (the hole injection / transport layer 104, the light-emitting layer 105, and the electron transport layer 108), and part of the light-receiving layer 103PS (the hole injection / transport layer 104, the active layer 105PS, and the electron transport layer 108) via the insulating layer 107.

[0279] In the EL layer 103 and the light receiving layer 103PS, the hole injection layer included in the hole transport region located between the anode and the light emitting layer, and between the anode and the active layer, often has high conductivity, and therefore may cause crosstalk if it is formed as a layer common to adjacent devices. Therefore, as shown in this configuration example, by separating a part of the EL layer 103 (hole injection / transport layer 104, light emitting layer 105, and electron transport layer 108) from a part of the light receiving layer 103PS (hole injection / transport layer 104, active layer 105PS, and electron transport layer 108) and providing an insulating layer 107 and a partition wall 528 between them, it is possible to suppress the occurrence of crosstalk occurring between adjacent devices.

[0280] In addition, it is also possible to flatten a recess formed between adjacent devices by providing the partition wall 528. By flattening the recess, it is possible to prevent disconnection of the electron injection layer 109 and the electrode 552 formed on the EL layer 103 and the light receiving layer 103PS.

[0281] For example, aluminum oxide, magnesium oxide, hafnium oxide, gallium oxide, indium gallium zinc oxide, silicon nitride, silicon nitride oxide, or the like can be used for the insulating layer 107. The insulating layer 107 may be formed by stacking the above-mentioned materials. The insulating layer 107 can be formed by a sputtering method, a CVD method, an MBE method, a PLD method, an ALD method, or the like, but the ALD method, which has good coverage, is more preferable.

[0282] As the insulating material used to form the partition 528, for example, an organic material such as an acrylic resin, a polyimide resin, an epoxy resin, an imide resin, a polyamide resin, a polyimideamide resin, a silicone resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, or a precursor of these resins can be used. In addition, an organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin may be used. In addition, a photosensitive resin such as a photoresist can be used. In addition, the photosensitive resin can be a positive material or a negative material.

[0283] By using a photosensitive resin, the partition 528 can be formed only by the steps of exposure and development. Alternatively, the partition 528 may be formed using a negative photosensitive resin (e.g., a resist material). When an insulating layer containing an organic material is used as the partition 528, it is preferable to use a material that absorbs visible light. When a material that absorbs visible light is used for the partition 528, it becomes possible for the partition 528 to absorb light emitted from the EL layer, and light (stray light) that may leak to the adjacent EL layer and light receiving layer can be suppressed. Therefore, a light receiving and emitting device with high display quality can be provided.

[0284] The difference in height between the upper surface of the partition 528 and the upper surface of either the EL layer 103 or the light receiving layer 103PS is, for example, preferably 0.5 times or less, more preferably 0.3 times or less, the thickness of the partition 528. For example, the partition 528 may be provided so that the upper surface of either the EL layer 103 or the light receiving layer 103PS is higher than the upper surface of the partition 528. For example, the partition 528 may be provided so that the upper surface of the partition 528 is higher than the upper surfaces of the light emitting layer of the EL layer 103 and the active layer of the light receiving layer 103PS.

[0285] In a high-definition light-emitting / receiving device exceeding 1000 ppi, if crosstalk occurs between devices, the color gamut that can be displayed by the light-emitting / receiving device becomes narrow. In a high-definition light-emitting / receiving device exceeding 1000 ppi, preferably a high-definition light-emitting / receiving device exceeding 2000 ppi, and more preferably an ultra-high-definition light-emitting / receiving device exceeding 5000 ppi, an insulating layer 107 and a partition wall 528 are provided between a part of the EL layer 103 (hole injection / transport layer 104, light-emitting layer 105B, and electron transport layer 108) and a part of the light-receiving layer 103PS (hole injection / transport layer 104, active layer 105PS, and electron transport layer 108), thereby providing a light-emitting / receiving device capable of displaying vivid colors.

[0286] 2(B) and 2(C) show schematic top views of the light receiving and emitting device 700 corresponding to the dashed line Ya-Yb in the cross-sectional view of FIG. 2(A). That is, each device is arranged in a matrix. FIG. 2(B) shows a so-called stripe arrangement in which light emitting devices or light receiving devices of the same color are arranged in the X direction. FIG. 2(C) shows a configuration in which light emitting devices or light receiving devices of the same color are arranged in the X direction, but a pattern is formed for each pixel. The arrangement method of the light emitting devices is not limited to this, and an arrangement method such as a delta arrangement or a zigzag arrangement may be applied, or a pentile arrangement, a diamond arrangement, or the like may be used.

[0287] In addition, since pattern formation is performed using photolithography in the separation processing of a part of the EL layer 103 (hole injection / transport layer 104, light-emitting layer 105, and electron transport layer 108) and a part of the light-receiving layer 103PS (hole injection / transport layer 104, active layer 105PS, and electron transport layer 108), a high-definition light-receiving / light-emitting device (display panel) can be manufactured. The ends (side surfaces) of each layer of the EL layer 103 and the ends (side surfaces) of each layer of the light-receiving layer 103PS processed by pattern formation using photolithography each have a shape having approximately the same surface (or are located on approximately the same plane). In this case, the width (SE) of the gap 580 between each EL layer and light-receiving layer is preferably 5 μm or less, more preferably 1 μm or less.

[0288] Fig. 2(D) is a schematic cross-sectional view corresponding to dashed line C1-C2 in Fig. 2(B) and Fig. 2(C). Fig. 2(D) shows connection portion 130 where connection electrode 551C and electrode 552 are electrically connected. In connection portion 130, electrode 552 is provided in contact with connection electrode 551C. Also, partition wall 528 is provided to cover the end of connection electrode 551C.

[0289] <Example of a manufacturing method for a light emitting / receiving device> 3A, an electrode 551B, an electrode 551G, an electrode 551R, and an electrode 551PS are formed. For example, a conductive film is formed on the functional layer 520 formed on the first substrate 510, and processed into a predetermined shape by photolithography.

[0290] The conductive film can be formed by sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), vacuum deposition, pulsed laser deposition (PLD), atomic layer deposition (ALD), etc. CVD methods include plasma enhanced chemical vapor deposition (PECVD) and thermal CVD. Metal organic chemical vapor deposition (MOCVD) is one type of thermal CVD.

[0291] In addition to the above-mentioned photolithography method, the conductive film may be processed by a nanoimprint method, a sandblast method, a lift-off method, etc. Also, an island-shaped thin film may be directly formed by a film formation method using a shielding mask such as a metal mask.

[0292] There are two typical photolithography methods. One is a method in which a resist mask is formed on a thin film to be processed, the thin film is processed by etching or the like, and the resist mask is removed. The other is a method in which a photosensitive thin film is formed, and then the thin film is processed into a desired shape by exposure and development. Note that the former method includes heat treatment steps such as baking after resist application (PAB: Pre Applied Bake) and baking after exposure (PEB: Post Exposure Bake). In one embodiment of the present invention, lithography is used not only for processing a conductive film, but also for processing a thin film (a film made of an organic compound or a film partially containing an organic compound) used to form an EL layer.

[0293] In the photolithography method, the light used for exposure may be, for example, i-line (wavelength 365 nm), g-line (wavelength 436 nm), h-line (wavelength 405 nm), or a mixture of these. In addition, ultraviolet light, KrF laser light, ArF laser light, or the like may be used. Exposure may also be performed by immersion exposure technology. Extreme ultraviolet (EUV) light or X-rays may also be used as the light used for exposure. Electron beams may also be used instead of light used for exposure. Extreme ultraviolet light, X-rays, or electron beams are preferable because they enable extremely fine processing. When exposure is performed by scanning a beam such as an electron beam, a photomask is not required.

[0294] For etching the thin film using a resist mask, a dry etching method, a wet etching method, a sandblasting method, or the like can be used.

[0295] Next, as shown in FIG. 3B, the hole injection / transport layer 104B, the light-emitting layer 105B, and the electron transport layer 108B are formed on the electrodes 551B, 551G, 551R, and 551PS. The hole injection / transport layer 104B, the light-emitting layer 105B, and the electron transport layer 108B can be formed by, for example, vacuum deposition. Furthermore, a sacrificial layer 110B is formed on the electron transport layer 108B. The materials shown in the first and second embodiments can be used to form the hole injection / transport layer 104B, the light-emitting layer 105B, and the electron transport layer 108B.

[0296] In addition, it is preferable to use a film having high resistance to the etching treatment of the hole injection / transport layer 104B, the light emitting layer 105B, and the electron transport layer 108B, that is, a film having a large etching selectivity, for the sacrificial layer 110B. In addition, it is preferable that the sacrificial layer 110B has a laminated structure of a first sacrificial layer and a second sacrificial layer having different etching selectivity. In addition, the sacrificial layer 110B can be a film that can be removed by a wet etching method that causes little damage to the EL layer 103B. Oxalic acid or the like can be used as an etching material for wet etching. In this specification and the like, the sacrificial layer may be called a mask layer.

[0297] The sacrificial layer 110B may be, for example, an inorganic film such as a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film. The sacrificial layer 110B may be formed by various film formation methods such as a sputtering method, a vapor deposition method, a CVD method, or an ALD method.

[0298] The sacrificial layer 110B may be made of a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum, or an alloy material containing the metal material. In particular, it is preferable to use a low melting point material such as aluminum or silver.

[0299] Also, as the sacrificial layer 110B, a metal oxide such as indium gallium zinc oxide (In-Ga-Zn oxide, also written as IGZO) can be used. Furthermore, indium oxide, indium zinc oxide (In-Zn oxide), indium tin oxide (In-Sn oxide), indium titanium oxide (In-Ti oxide), indium tin zinc oxide (In-Sn-Zn oxide), indium titanium zinc oxide (In-Ti-Zn oxide), indium gallium tin zinc oxide (In-Ga-Sn-Zn oxide), etc. can be used. Alternatively, indium tin oxide containing silicon, etc. can be used.

[0300] The present invention can also be applied to a case where an element M (wherein M is one or more elements selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) is used instead of the above-mentioned gallium. In particular, it is preferable that M is one or more elements selected from gallium, aluminum, and yttrium.

[0301] The sacrificial layer 110B may be made of an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide.

[0302] In addition, it is preferable to use a material that can be dissolved in a chemically stable solvent for at least the uppermost electron transport layer 108B as the sacrificial layer 110B. In particular, a material that dissolves in water or alcohol can be suitably used for the sacrificial layer 110B. When forming the sacrificial layer 110B, it is preferable to apply the sacrificial layer 110B by a wet film formation method in a state where the sacrificial layer 110B is dissolved in a solvent such as water or alcohol, and then perform a heat treatment to evaporate the solvent. At this time, by performing the heat treatment under a reduced pressure atmosphere, the solvent can be removed at a low temperature in a short time, and therefore thermal damage to the hole injection / transport layer 104B, the light-emitting layer 105B, and the electron transport layer 108B can be reduced, which is preferable.

[0303] When the sacrificial layer 110B has a laminated structure, a layer made of the above-mentioned material may be used as a first sacrificial layer, and a second sacrificial layer may be formed thereon to form a laminated structure.

[0304] In this case, the second sacrificial layer is a film used as a hard mask when etching the first sacrificial layer. In addition, when processing the second sacrificial layer, the first sacrificial layer is exposed. Therefore, the first sacrificial layer and the second sacrificial layer are selected as a combination of films having a large etching selectivity. Therefore, a film that can be used for the second sacrificial layer can be selected according to the etching conditions of the first sacrificial layer and the etching conditions of the second sacrificial layer.

[0305] For example, when dry etching using a gas containing fluorine (also called a fluorine-based gas) is used for etching the second sacrificial layer, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, or an alloy containing molybdenum and tungsten can be used for the second sacrificial layer. Here, as a film that can have a large etching selectivity (i.e., can slow down the etching rate) with respect to the dry etching using the fluorine-based gas, there are metal oxide films such as IGZO and ITO, which can be used for the first sacrificial layer.

[0306] However, the second sacrificial layer is not limited to this, and can be selected from various materials according to the etching conditions of the first sacrificial layer and the etching conditions of the second sacrificial layer. For example, it can be selected from the films that can be used for the first sacrificial layer.

[0307] The second sacrificial layer may be, for example, a nitride film, such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride.

[0308] Alternatively, an oxide film can be used as the second sacrificial layer. Typically, an oxide film or an oxynitride film such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can be used.

[0309] Next, as shown in Fig. 3(C), resist is applied onto the sacrificial layer 110B, and the resist is formed into a desired shape (resist mask: REG) using photolithography. When performing such a method, there are heat treatment steps such as heating after resist application (PAB: Pre Applied Bake) and heating after exposure (PEB: Post Exposure Bake). For example, the PAB temperature is around 100°C, and the PEB temperature is around 120°C. Therefore, it is necessary for the light emitting device to be able to withstand these processing temperatures.

[0310] Next, the obtained resist mask REG is used to etch away a portion of the sacrificial layer 110B that is not covered by the resist mask REG, and after removing the resist mask REG, the hole injection / transport layer 104B, the light emitting layer 105B, and the electron transport layer 108B that are not covered by the sacrificial layer 110B are etched away to process the hole injection / transport layer 104B, the light emitting layer 105B, and the electron transport layer 108B into a shape having a side surface on the electrode 551B (or a side surface is exposed) or into a strip shape extending in a direction intersecting the paper surface. Dry etching is preferable for the etching. When the sacrificial layer 110B has a laminated structure of the first sacrificial layer and the second sacrificial layer, a portion of the second sacrificial layer may be etched by the resist mask REG, and then a portion of the first sacrificial layer may be etched using the second sacrificial layer as a mask, to process the hole injection / transport layer 104B, the light emitting layer 105B, and the electron transport layer 108B into a predetermined shape. By these etching processes, the shape shown in FIG. 4(A) is obtained.

[0311] 4(B), a hole injection / transport layer 104G, a light emitting layer 105G, and an electron transport layer 108G are formed on the sacrificial layer 110B, the electrode 551G, the electrode 551R, and the electrode 551PS. The materials used in forming the hole injection / transport layer 104G, the light emitting layer 105G, and the electron transport layer 108G may be the same as those used in the first and second embodiments. The hole injection / transport layer 104G, the light emitting layer 105G, and the electron transport layer 108G may be formed by vacuum deposition, for example.

[0312] Thereafter, in the same manner as in the formation of the hole injection / transport layer 104B, the light-emitting layer 105B, the electron transport layer 108B, and the sacrificial layer 110B, a hole injection / transport layer 104G, the light-emitting layer 105G, the electron transport layer 108G, and the sacrificial layer 110G are formed on the electrode 551G, a hole injection / transport layer 104R, the light-emitting layer 105R, the electron transport layer 108R, and the sacrificial layer 110R are formed on the electrode 551R, and a hole injection / transport layer 104PS, the active layer 105PS, the electron transport layer 108PS, and the sacrificial layer 110PS are formed on the electrode 551PS, thereby obtaining the shape shown in FIG. 4(C).

[0313] Next, as shown in FIG. 5(A), the insulating layer 107 is formed on the sacrificial layers 110B, 110G, 110R, and 110PS.

[0314] The insulating layer 107 can be formed by, for example, ALD. In this case, the insulating layer 107 is formed in contact with each side surface (each end portion) of the hole injection / transport layers (104B, 104G, 104R, 104PS), the light-emitting layers (103R, 103G, 103R), the active layer 105PS, and the electron transport layers (108B, 108G, 108R, 108PS) of each device, as shown in Fig. 5(A). This makes it possible to prevent oxygen, moisture, or their constituent elements from penetrating into the inside from each side surface.

[0315] 5(B), a resin film 528a is formed on the insulating layer 107. For example, a negative photosensitive resin or a positive photosensitive resin can be used as the resin film 528a.

[0316] Next, as shown in FIG. 5C, a portion of the resin film 528a, a portion of the insulating layer 107, and the sacrificial layers (110B, 110G, 110R, 110PS) are removed to expose the upper surface of the electron transport layer (108B, 108G, 108R, 108PS).

[0317] 5(D), a heat treatment is performed to curve the upper end of the resin film 528a, thereby forming the partition wall 528. By curvedly shaping the upper end of the partition wall 528, it is possible to improve the coverage of the electron injection layer 109 to be formed later. For example, when a positive photosensitive acrylic resin is used as the resin film 528a, it is preferable that the upper end of the partition wall 528 has a curved surface with a radius of curvature (0.2 μm to 3 μm).

[0318] Next, the electron injection layer 109 is formed over the insulating layer 107, the electron transport layers (108B, 108G, 108R, and 108PS), and the partition 528. The electron injection layer 109 can be formed using the materials described in Embodiment 2. Note that the electron injection layer 109 is formed by, for example, a vacuum evaporation method.

[0319] 6A, an electrode 552 is formed on the electron-injection layer 109. The electrode 552 is formed by, for example, a vacuum deposition method.

[0320] Through the above steps, EL layers 103B, 103G, 103R, and light receiving layers 103PS in light emitting devices 550B, 550G, and 550R, and light receiving device 550PS can be processed separately.

[0321] As described above, in the separation process of the EL layer 103 and the light receiving layer 103PS, a high-definition light receiving and emitting device (display panel) can be manufactured by forming a pattern using photolithography. In addition, the end (side) of each layer of the EL layer and the light receiving layer processed by pattern formation using photolithography has a shape having approximately the same surface (or being located on approximately the same plane). In addition, by forming a pattern using photolithography, it is possible to suppress the occurrence of crosstalk occurring between adjacent light emitting devices and light receiving devices. In addition, there is a gap 580 between adjacent devices processed by pattern formation using photolithography. In FIG. 6(C), when the gap 580 is represented by the distance SE between the EL layers of adjacent light emitting devices, the smaller the distance SE, the higher the aperture ratio and the higher the definition. On the other hand, the larger the distance SE, the higher the manufacturing yield can be because the influence of the manufacturing process variation between adjacent light emitting devices can be tolerated. Since the light-emitting devices fabricated according to the present specification are suitable for miniaturization processes, the distance SE between the EL layers of adjacent light-emitting devices can be 0.5 μm to 5 μm, preferably 1 μm to 3 μm, more preferably 1 μm to 2.5 μm, and even more preferably 1 μm to 2 μm. Typically, the distance SE is preferably 1 μm to 2 μm (e.g., 1.5 μm or close thereto).

[0322] In this specification etc., a device fabricated using a metal mask or FMM (fine metal mask, high-definition metal mask) may be referred to as a device with an MM (metal mask) structure. In addition, in this specification etc., a device fabricated without using a metal mask or FMM may be referred to as a device with an MML (metal maskless) structure. Since a light emitting and receiving device with an MML structure is fabricated without using a metal mask, it has a higher degree of design freedom in terms of pixel arrangement, pixel shape, etc. than a light emitting and receiving device with an FMM structure or an MM structure.

[0323] The island-shaped EL layer of the MML-structure light-receiving / emitting device is not formed by a metal mask pattern, but is formed by processing the EL layer after it is formed. This makes it possible to realize light-receiving / emitting devices with higher resolution or a higher aperture ratio than ever before. Furthermore, since the EL layer can be made separately for each color, it is possible to realize light-receiving / emitting devices that are extremely vivid, have high contrast, and have high display quality. Furthermore, by providing a sacrificial layer on the EL layer, damage to the EL layer during the manufacturing process can be reduced, thereby improving the reliability of the light-emitting device.

[0324] In the light-emitting device 550 shown in Figures 2(A) and 6(A), the width of the EL layer 103 is approximately equal to the width of the electrode 551, and in the light-receiving device 550PS, the width of the light-receiving layer 103PS is approximately equal to the width of the electrode 551PS, but one embodiment of the present invention is not limited to this.

[0325] In the light-emitting device 550, the width of the EL layer 103 may be smaller than the width of the electrode 551. In the light-receiving device 550PS, the width of the light-receiving layer 103PS may be smaller than the width of the electrode 551PS. Fig. 6(B) shows an example in which the width of the EL layer 103B is smaller than the width of the electrode 551B in the light-emitting device 550B.

[0326] In addition, in the light-emitting device 550, the width of the EL layer 103 may be larger than the width of the electrode 551. In the light-receiving device 550PS, the width of the light-receiving layer 103PS may be larger than the width of the electrode 551PS. Fig. 6(C) shows an example in which the width of the EL layer 103R is larger than the width of the electrode 551R in the light-emitting device 550R.

[0327] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0328] (Embodiment 4) In this embodiment, the device 720 will be described with reference to Figs. 7 and 8. The device 720 shown in Figs. 7 and 8 is a light-emitting device since it has the light-emitting device shown in the first and second embodiments, but it can also be called a display panel or a display device since it is applicable to the display unit of an electronic device or the like. In addition, when the device is configured to use the light-emitting device as a light source and to include a light-receiving device capable of receiving light from the light-emitting device, it can also be called a light-receiving and emitting device. These light-emitting devices, display panels, display devices, and light-receiving and emitting devices are configured to include at least a light-emitting device.

[0329] The light-emitting device, the display panel, the display device, and the light-receiving and light-emitting device of the present embodiment can be a high-resolution or large light-emitting device, a display panel, a display device, and a light-receiving and light-emitting device. Therefore, the light-emitting device, the display panel, the display device, and the light-receiving and light-emitting device of the present embodiment can be used for the display unit of electronic devices having a relatively large screen, such as a television device, a desktop or notebook personal computer, a monitor for a computer, digital signage, a large game machine such as a pachinko machine, as well as a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game machine, a smartphone, a wristwatch-type terminal, a tablet terminal, a mobile information terminal, and an audio reproducing device.

[0330] FIG. 7A shows a top view of device 720.

[0331] 7(A), a device 720 has a structure in which a substrate 710 and a substrate 711 are bonded together. The device 720 also has a display region 701, a circuit 704, and wiring 706. Note that the display region 701 has a plurality of pixels, and a pixel 703(i,j) shown in FIG. 7(A) is adjacent to a pixel 703(i+1,j) as shown in FIG. 7(B).

[0332] 7A, the device 720 has an example in which an IC (integrated circuit) 712 is provided on a substrate 710 by a chip on glass (COG) method or a chip on film (COF) method. Note that an IC having a scanning line driver circuit or a signal line driver circuit, for example, can be used as the IC 712. In FIG. 7A, an IC having a signal line driver circuit is used as the IC 712, and a configuration having a scanning line driver circuit is shown as the circuit 704.

[0333] The wiring 706 has a function of supplying signals and power to the display region 701 and the circuit 704. The signals and power are input to the wiring 706 from the outside via a flexible printed circuit (FPC) 713, or are input to the wiring 706 from an IC 712. Note that the device 720 may not include an IC. Alternatively, the IC may be mounted on the FPC by a COF method or the like.

[0334] FIG. 7B shows pixels 703(i,j) and 703(i+1,j) in the display region 701. That is, the pixel 703(i,j) can be configured to have a plurality of subpixels having light-emitting devices that emit different colors. Alternatively, in addition to the above, the pixel can be configured to include a plurality of subpixels having light-emitting devices that emit the same color. For example, the pixel can be configured to have three types of subpixels. The three subpixels can be subpixels of three colors, red (R), green (G), and blue (B), or subpixels of three colors, yellow (Y), cyan (C), and magenta (M). Alternatively, the pixel can be configured to have four types of subpixels. The four subpixels can be subpixels of four colors, R, G, B, and white (W), or subpixels of four colors, R, G, B, and Y. Specifically, the pixel 703(i,j) may be composed of a sub-pixel 702B(i,j) that displays blue, a sub-pixel 702G(i,j) that displays green, and a sub-pixel 702R(i,j) that displays red.

[0335] Furthermore, the subpixel may have not only a light-emitting device but also a light-receiving device. When the subpixel has a light-receiving device, the device 720 is also called a light-receiving / light-emitting device.

[0336] Pixels 703(i,j) shown in Figures 7(C) to 7(F) show examples of various layouts including sub-pixels 702PS(i,j) having light receiving devices. The pixel arrangement shown in Figure 7(C) is a stripe arrangement, and the pixel arrangement shown in Figure 7(D) is a matrix arrangement. The pixel arrangement shown in Figure 7(E) has a configuration in which three sub-pixels (sub-pixels R, G, and PS) are vertically arranged next to one sub-pixel (sub-pixel B).

[0337] Also, as shown in Fig. 7(F), a subpixel 702IR(i,j) that emits infrared light may be added to the above set to form pixel 703(i,j). The pixel arrangement shown in Fig. 7(F) has a configuration in which three vertically elongated subpixels G, B, and R are arranged horizontally, and below them, a subpixel PS and a horizontally elongated subpixel IR are arranged horizontally. Specifically, a subpixel 702IR(i,j) that emits light including light having a wavelength of 650 nm or more and 1000 nm or less may be used for pixel 703(i,j). Although the wavelength of light detected by subpixel 702PS(i,j) is not particularly limited, it is preferable that the light receiving device of subpixel 702PS(i,j) is sensitive to light emitted by the light emitting device of subpixel 702R(i,j), subpixel 702G(i,j), subpixel 702B(i,j), or subpixel 702IR(i,j). For example, it is preferable to detect one or more of light in wavelength ranges such as blue, purple, blue-purple, green, yellow-green, yellow, orange, and red, and light in the infrared wavelength range.

[0338] The arrangement of the sub-pixels is not limited to the configurations shown in Fig. 7B to Fig. 7F, and various methods can be applied. Examples of the arrangement of the sub-pixels include a stripe arrangement, an S-stripe arrangement, a matrix arrangement, a delta arrangement, a Bayer arrangement, and a Pentile arrangement.

[0339] Examples of the top surface shape of the subpixel include a triangle, a quadrangle (including a rectangle and a square), a polygon such as a pentagon, a shape with rounded corners of these polygons, an ellipse, a circle, etc. The top surface shape of the subpixel here corresponds to the top surface shape of the light-emitting region of the light-emitting device.

[0340] In the case where a pixel has not only a light-emitting device but also a light-receiving device, the pixel has a light-receiving function, and therefore it is possible to detect the contact or proximity of an object while displaying an image. For example, in addition to displaying an image using all of the sub-pixels of the light-emitting device, some of the sub-pixels can emit light as a light source and the remaining sub-pixels can display an image.

[0341] It is preferable that the light receiving area of ​​the sub-pixel 702PS(i,j) is smaller than the light emitting area of ​​the other sub-pixels. The smaller the light receiving area, the narrower the imaging range, making it possible to suppress blurring of the imaging result and improve the resolution. Therefore, by using the sub-pixel 702PS(i,j), it is possible to perform imaging with high definition or high resolution. For example, the sub-pixel 702PS(i,j) can be used to perform imaging for personal authentication using a fingerprint, palm print, iris, pulse shape (including vein shape and artery shape), face, or the like.

[0342] The subpixel 702PS(i,j) can be used as a touch sensor (also called a direct touch sensor) or a near-touch sensor (also called a hover sensor, hover touch sensor, non-contact sensor, or touchless sensor). For example, the subpixel 702PS(i,j) preferably detects infrared light. This allows touch detection even in a dark place.

[0343] Here, the touch sensor or near-touch sensor can detect the proximity or contact of an object (such as a finger, a hand, or a pen). The touch sensor can detect an object by directly contacting the light receiving / emitting device with the object. The near-touch sensor can detect the object even if the object does not contact the light receiving / emitting device. For example, it is preferable that the light receiving / emitting device can detect the object when the distance between the light receiving / emitting device and the object is in the range of 0.1 mm to 300 mm, preferably 3 mm to 50 mm. With this configuration, it is possible to operate the light receiving / emitting device without the object directly touching it, in other words, it is possible to operate the light receiving / emitting device in a non-contact (touchless) manner. With the above configuration, it is possible to reduce the risk of the light receiving / emitting device becoming dirty or scratched, or it is possible to operate the light receiving / emitting device without the object directly touching dirt (such as dust, bacteria, or viruses) attached to the light receiving / emitting device.

[0344] When the sub-pixel 702PS(i,j) is used for high-definition imaging, it is preferable that the sub-pixel 702PS(i,j) is provided in all pixels. On the other hand, when the sub-pixel 702PS(i,j) is used for a touch sensor or near-touch sensor, high accuracy is not required compared to imaging a fingerprint, and therefore it is sufficient to provide the sub-pixel 702PS(i,j) in some pixels. The detection speed can be increased by making the number of sub-pixels 702PS(i,j) in the light emitting and receiving device smaller than the number of sub-pixels 702R(i,j), etc.

[0345] Next, an example of a specific structure of a transistor that can be used in a pixel circuit of a subpixel having a light-emitting device is shown in FIG. Note that a bottom-gate transistor or a top-gate transistor can be used as the transistor as appropriate.

[0346] 8A includes a semiconductor film 508, a conductive film 504, an insulating film 506, a conductive film 512A, and a conductive film 512B. The transistor is formed over, for example, an insulating film 501C. The transistor also includes an insulating film 516 (insulating films 516A and 516B) and an insulating film 518.

[0347] The semiconductor film 508 has a region 508A electrically connected to the conductive film 512A and a region 508B electrically connected to the conductive film 512B. The semiconductor film 508 has a region 508C between the region 508A and the region 508B.

[0348] The conductive film 504 has a region overlapping with the region 508C, and functions as a gate electrode.

[0349] The insulating film 506 has a region sandwiched between the semiconductor film 508 and the conductive film 504. The insulating film 506 functions as a first gate insulating film.

[0350] The conductive film 512A has either a function of a source electrode or a function of a drain electrode, and the conductive film 512B has the other function of a source electrode or a drain electrode.

[0351] The conductive film 524 can be used for a transistor. The conductive film 524 has a region where the semiconductor film 508 is sandwiched between the conductive film 524 and the conductive film 504. The conductive film 524 functions as a second gate electrode. The insulating film 501D is sandwiched between the semiconductor film 508 and the conductive film 524 and functions as a second gate insulating film.

[0352] The insulating film 516 functions as, for example, a protective film that covers the semiconductor film 508. As the insulating film 516, specifically, for example, a film containing a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, or a neodymium oxide film can be used.

[0353] The insulating film 518 is preferably formed using a material that has a function of suppressing diffusion of, for example, oxygen, hydrogen, water, an alkali metal, an alkaline earth metal, and the like. Specifically, for example, silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxynitride, or the like can be used for the insulating film 518. The number of oxygen atoms contained in silicon oxynitride and the number of nitrogen atoms contained in aluminum oxynitride are preferably greater than the number of oxygen atoms contained in the silicon oxynitride and the aluminum oxynitride.

[0354] Note that a semiconductor film to be used for a transistor in a driver circuit can be formed in a process of forming a semiconductor film to be used for a transistor in a pixel circuit. For example, a semiconductor film having the same composition as that of the semiconductor film to be used for a transistor in a pixel circuit can be used for the driver circuit.

[0355] The semiconductor film 508 preferably contains, for example, indium, M (M is one or more selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc. In particular, M is preferably one or more selected from aluminum, gallium, yttrium, and tin.

[0356] In particular, it is preferable to use an oxide containing In, Ga, and Zn (also referred to as IGZO) as the semiconductor film 508. Alternatively, it is preferable to use an oxide containing In, Sn, and Zn. Alternatively, it is preferable to use an oxide containing In, Ga, Sn, and Zn. Alternatively, it is preferable to use an oxide containing In, Al, and Zn (also referred to as IAZO). Alternatively, it is preferable to use an oxide containing In, Al, Ga, and Zn (also referred to as IAGZO).

[0357] When the semiconductor film is an In-M-Zn oxide, the atomic ratio of In in the In-M-Zn oxide is preferably equal to or greater than the atomic ratio of M. The atomic ratios of metal elements in such an In-M-Zn oxide include a composition of In:M:Zn=1:1:1 or nearby, In:M:Zn=1:1:1.2 or nearby, In:M:Zn=1:3:2 or nearby, In:M:Zn=1:3:4 or nearby, In:M:Zn=2:1:3 or nearby, In:M:Zn=3:1:2 or nearby, In:M:Zn=4:2:3 or a composition in the vicinity thereof, In:M:Zn=4:2:4.1 or a composition in the vicinity thereof, In:M:Zn=5:1:3 or a composition in the vicinity thereof, In:M:Zn=5:1:6 or a composition in the vicinity thereof, In:M:Zn=5:1:7 or a composition in the vicinity thereof, In:M:Zn=5:1:8 or a composition in the vicinity thereof, In:M:Zn=6:1:6 or a composition in the vicinity thereof, In:M:Zn=5:2:5 or a composition in the vicinity thereof, etc. Note that a composition in the vicinity thereof includes a range of ±30% of the desired atomic ratio.

[0358] For example, when describing a composition with an atomic ratio of In:Ga:Zn=4:2:3 or thereabout, it includes the case where, when the atomic ratio of In is 4, the atomic ratio of Ga is 1 or more and 3 or less, and the atomic ratio of Zn is 2 or more and 4 or less. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=5:1:6 or thereabout, it includes the case where, when the atomic ratio of In is 5, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is 5 or more and 7 or less. Furthermore, when describing a composition with an atomic ratio of In:Ga:Zn=1:1:1 or thereabout, it includes the case where, when the atomic ratio of In is 1, the atomic ratio of Ga is more than 0.1 and 2 or less, and the atomic ratio of Zn is more than 0.1 and 2 or less.

[0359] The crystallinity of a semiconductor material used in a transistor is not particularly limited, and any of an amorphous semiconductor and a crystalline semiconductor (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partially having a crystalline region) may be used. The use of a crystalline semiconductor is preferable because it can suppress deterioration of transistor characteristics.

[0360] When a metal oxide is used for the semiconductor film 508, the device 720 has a configuration in which a metal oxide is used for the semiconductor film and a light-emitting device has an MML (metal maskless) structure. With this configuration, it is possible to extremely reduce a leakage current that may flow through a transistor and a leakage current that may flow between adjacent light-emitting devices (also called a lateral leakage current or a side leakage current). In addition, with the above configuration, when an image is displayed on a display device, an observer can observe one or more of image sharpness, image sharpness, high saturation, and a high contrast ratio. Note that, with a configuration in which the leakage current that may flow through a transistor and the lateral leakage current between light-emitting devices are extremely low, it is possible to achieve a display (also called a true black display) with extremely little light leakage (so-called black floating) that may occur during black display.

[0361] Silicon may be used for the semiconductor film 508. Examples of silicon include single crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, it is preferable to use a transistor having low temperature polysilicon (LTPS (Low Temperature Poly Silicon)) in the semiconductor layer (hereinafter, also referred to as an LTPS transistor). The LTPS transistor has high field effect mobility and good frequency characteristics.

[0362] By using silicon transistors such as LTPS transistors, circuits that need to be driven at high frequencies (such as source driver circuits) can be built on the same substrate as the display unit, simplifying the external circuits mounted on the light-emitting device and reducing component and mounting costs.

[0363] In addition, the configuration of the transistors used in the display panel may be appropriately selected according to the screen size of the display panel. For example, when single crystal Si transistors are used as the transistors of the display panel, the display panel can be applied to a screen size with a diagonal size of 0.1 inch to 3 inches. When LTPS transistors are used as the transistors of the display panel, the display panel can be applied to a screen size with a diagonal size of 0.1 inch to 30 inches, preferably 1 inch to 30 inches. When LTPO (a configuration in which LTPS transistors and OS transistors are combined) is used in the display panel, the display panel can be applied to a screen size with a diagonal size of 0.1 inch to 50 inches, preferably 1 inch to 50 inches. When OS transistors (transistors having metal oxide in a semiconductor in which a channel is formed) are used as the transistors of the display panel, the display panel can be applied to a screen size with a diagonal size of 0.1 inch to 200 inches, preferably 50 inch to 100 inches.

[0364] It is very difficult to increase the size of a single crystal Si transistor due to the size of a single crystal Si substrate. In addition, since a laser crystallization device is used in the manufacturing process of an LTPS transistor, it is difficult to accommodate large sizes (typically, screen sizes exceeding 30 inches in diagonal size). On the other hand, since an OS transistor is not restricted by the use of a laser crystallization device or the like in the manufacturing process, or can be manufactured at a relatively low process temperature (typically 450° C. or lower), it is possible to accommodate display panels with a relatively large area (typically, 50 inches to 100 inches in diagonal size). In addition, LTPO can be applied to sizes between the size when an LTPS transistor is used and the size when an OS transistor is used (typically, 1 inch to 50 inches in diagonal size).

[0365] Next, a cross-sectional view of the light emitting and receiving device shown in FIG.

[0366] The cross-sectional view of FIG. 8B shows a cross-sectional view of a part of the region including the FPC 713 and the wiring 706, and a part of the display region 701 including the pixel 703(i,j).

[0367] In Fig. 8(B), the light receiving and emitting device 700 has a functional layer 520 between a first substrate 510 and a second substrate 770. The functional layer 520 includes the above-mentioned transistors and capacitive elements, as well as wirings that electrically connect these elements. Note that, in Fig. 8(B), the functional layer 520 includes a pixel circuit 530X(i,j), a pixel circuit 530S(i,j), and a circuit GD, but is not limited thereto.

[0368] In addition, the pixel circuits (for example, the pixel circuits 530X(i,j) and 530S(i,j) shown in FIG. 8B) formed in the functional layer 520 are electrically connected to the light-emitting devices and light-receiving devices (for example, the light-emitting devices 550X(i,j) and the light-receiving devices 550S(i,j) shown in FIG. 8B) formed on the functional layer 520. Specifically, the light-emitting devices 550X(i,j) are electrically connected to the pixel circuits 530X(i,j) via the wiring 591X, and the light-receiving devices 550S(i,j) are electrically connected to the pixel circuits 530S(i,j) via the wiring 591S. In addition, an insulating layer 705 is provided on the functional layer 520, the light-emitting devices, and the light-receiving devices, and the insulating layer 705 has a function of bonding the second substrate 770 and the functional layer 520 together.

[0369] Note that a substrate provided with touch sensors arranged in a matrix can be used as the second substrate 770. For example, a substrate provided with a capacitive touch sensor or an optical touch sensor can be used as the second substrate 770. In this way, the light-emitting and receiving device of one embodiment of the present invention can be used as a touch panel.

[0370] Note that the structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiments.

[0371] (Embodiment 5) In this embodiment, the structure of an electronic device of one embodiment of the present invention will be described with reference to FIGS.

[0372] 9(A) to 11(B) are diagrams illustrating the configuration of an electronic device of one embodiment of the present invention. FIG. 9(A) is a block diagram of an electronic device, and FIG. 9(B) to FIG. 9(E) are perspective views illustrating the configuration of the electronic device. FIG. 10(A) to FIG. 10(E) are perspective views illustrating the configuration of the electronic device. FIG. 11(A) and FIG. 11(B) are perspective views illustrating the configuration of the electronic device.

[0373] An electronic device 5200B described in this embodiment includes an arithmetic device 5210 and an input / output device 5220 (see FIG. 9A).

[0374] The arithmetic unit 5210 has a function of receiving operation information and a function of supplying image information based on the operation information.

[0375] The input / output device 5220 has a display unit 5230, an input unit 5240, a detection unit 5250, a communication unit 5290, a function of supplying operation information, and a function of being supplied with image information. The input / output device 5220 also has a function of supplying detection information, a function of supplying communication information, and a function of being supplied with communication information.

[0376] The input unit 5240 has a function of supplying operation information. For example, the input unit 5240 supplies operation information based on an operation by a user of the electronic device 5200B.

[0377] Specifically, the input unit 5240 can use a keyboard, a hardware button, a pointing device, a touch sensor, an illuminance sensor, an imaging device, a voice input device, an eye-gaze input device, a posture detection device, or the like.

[0378] The display portion 5230 has a function of displaying a display panel and displaying image information. For example, the display panel described in Embodiment 3 can be used for the display portion 5230.

[0379] The detection unit 5250 has a function of supplying detection information, for example, a function of detecting the surrounding environment in which the electronic device is used and supplying the detected information.

[0380] Specifically, the detection unit 5250 can include an illuminance sensor, an imaging device, a posture detection device, a pressure sensor, a human sensor, or the like.

[0381] The communication unit 5290 has a function of receiving and supplying communication information. For example, it has a function of connecting to other electronic devices or communication networks by wireless communication or wired communication. Specifically, it has functions such as wireless local area communication, telephone communication, and short-distance wireless communication.

[0382] FIG. 9B shows an electronic device having an outer shape along a cylindrical pillar or the like. One example is a digital signage. The display panel of one embodiment of the present invention can be applied to the display portion 5230. Note that the display panel may have a function of changing the display method depending on the illuminance of the usage environment. The display panel may also have a function of detecting the presence of a person and changing the display content. Thus, the display panel can be installed on a pillar of a building, for example. Alternatively, advertisements, guidance, or the like can be displayed.

[0383] Fig. 9(C) shows an electronic device having a function of generating image information based on the trajectory of a pointer used by a user. Examples include an electronic whiteboard, an electronic bulletin board, an electronic signboard, etc. Specifically, a display panel with a diagonal length of 20 inches or more, preferably 40 inches or more, more preferably 55 inches or more can be used. Alternatively, multiple display panels can be arranged to be used in one display area. Alternatively, multiple display panels can be arranged to be used in a multi-screen.

[0384] FIG. 9D shows an electronic device that can receive information from another device and display it on the display unit 5230. An example of the electronic device is a wearable electronic device. Specifically, several options can be displayed, or a user can select some of the options and send the selected information back to a sender of the information. Alternatively, the electronic device has a function of changing the display method according to the illuminance of the usage environment. This can reduce the power consumption of the wearable electronic device, for example. Alternatively, an image can be displayed on the wearable electronic device so that the electronic device can be used suitably even in an environment with strong external light, such as outdoors on a sunny day.

[0385] 9(E) shows an electronic device having a display unit 5230 with a curved surface that is gently curved along the side surface of the housing. An example is a mobile phone. The display unit 5230 has a display panel, and the display panel has a function of displaying information on, for example, the front, side, top, and back of the mobile phone. This allows information to be displayed not only on the front of the mobile phone, but also on the side, top, and back.

[0386] FIG. 10A shows an electronic device that can receive information from the Internet and display it on the display unit 5230. An example of the electronic device is a smartphone. For example, a created message can be confirmed on the display unit 5230. Or, the created message can be transmitted to another device. Or, for example, the smartphone has a function of changing the display method according to the illuminance of the usage environment. This can reduce the power consumption of the smartphone. Or, for example, an image can be displayed on the smartphone so that the smartphone can be used suitably even in an environment with strong external light, such as outdoors on a sunny day.

[0387] FIG. 10(B) shows an electronic device in which a remote controller can be used as the input unit 5240. An example is a television system. Alternatively, for example, information can be received from a broadcasting station or the Internet and displayed on the display unit 5230. Alternatively, a user can be photographed using the detection unit 5250. Alternatively, a video of the user can be transmitted. Alternatively, a viewing history of the user can be acquired and provided to a cloud service. Alternatively, recommendation information can be acquired from a cloud service and displayed on the display unit 5230. Alternatively, a program or video can be displayed based on the recommendation information. Alternatively, for example, the device has a function of changing the display method according to the illuminance of the usage environment. As a result, the video can be displayed on the television system so that it can be used suitably even when strong external light shines into the room on a sunny day.

[0388] 10C shows an electronic device that can receive learning materials from the Internet and display them on the display unit 5230. An example is a tablet computer. Alternatively, a report can be input using the input unit 5240 and transmitted to the Internet. Alternatively, a correction result or evaluation of the report can be obtained from a cloud service and displayed on the display unit 5230. Alternatively, suitable learning materials can be selected and displayed based on the evaluation.

[0389] For example, an image signal can be received from another electronic device and displayed on the display unit 5230. Alternatively, the display unit 5230 can be used as a sub-display by leaning it against a stand or the like. This allows images to be displayed on the tablet computer so that it can be used suitably even in an environment with strong external light, such as outdoors on a sunny day.

[0390] FIG. 10D shows an electronic device having a plurality of display units 5230. One example is a digital camera. For example, an image can be captured by the detection unit 5250 and displayed on the display unit 5230. Alternatively, the captured image can be displayed on the detection unit. Alternatively, the captured image can be decorated using the input unit 5240. Alternatively, a message can be attached to the captured image. Alternatively, the captured image can be transmitted to the Internet. Alternatively, the electronic device has a function of changing the capture conditions according to the illuminance of the usage environment. This allows the subject to be displayed on the digital camera so that it can be viewed favorably even in an environment with strong external light, such as outdoors on a sunny day.

[0391] FIG. 10(E) shows an electronic device that can control another electronic device by using the electronic device of this embodiment as a master while using the other electronic device as a slave. One example is a portable personal computer. For example, a part of the image information can be displayed on the display unit 5230, and another part of the image information can be displayed on the display unit of the other electronic device. Alternatively, an image signal can be supplied. Alternatively, information to be written can be obtained from an input unit of the other electronic device using the communication unit 5290. This allows a wide display area to be used, for example, by using a portable personal computer.

[0392] FIG. 11(A) shows an electronic device having a detection unit 5250 that detects acceleration or orientation. An example is a goggle-type electronic device. Alternatively, the detection unit 5250 can supply information related to the position of the user or the direction in which the user is facing. Alternatively, the electronic device can generate image information for the right eye and image information for the left eye based on the position of the user or the direction in which the user is facing. Alternatively, the display unit 5230 has a display area for the right eye and a display area for the left eye. This allows, for example, an image of a virtual reality space that provides an immersive feeling to be displayed on the goggle-type electronic device.

[0393] FIG. 11B shows an electronic device having a detection unit 5250 that detects an imaging device, acceleration, or orientation. An example is a glasses-type electronic device. Alternatively, the detection unit 5250 can provide information related to the user's position or the direction in which the user is facing. Alternatively, the electronic device can generate image information based on the user's position or the direction in which the user is facing. This makes it possible to display, for example, information attached to a real landscape. Alternatively, an image of an augmented reality space can be displayed on the glasses-type electronic device.

[0394] Note that this embodiment mode can be appropriately combined with other embodiment modes described in this specification.

[0395] (Embodiment 6) In this embodiment, a structure in which the light-emitting device described in Embodiment 2 is used as a lighting device will be described with reference to Fig. 12. Fig. 12(A) is a cross-sectional view taken along line ef in a top view of the lighting device shown in Fig. 12(B).

[0396] In the lighting device in this embodiment, a first electrode 401 is formed over a light-transmitting substrate 400, which is a support. The first electrode 401 corresponds to the first electrode 101 in Embodiment 2. When light is extracted from the first electrode 401 side, the first electrode 401 is formed using a light-transmitting material.

[0397] A pad 412 for supplying a voltage to the second electrode 404 is formed on the substrate 400 .

[0398] An EL layer 403 is formed over the first electrode 401. The EL layer 403 has a structure corresponding to the EL layer 103 in Embodiment 2. For the structure thereof, refer to the description therein.

[0399] A second electrode 404 is formed to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in the second embodiment. When light is extracted from the first electrode 401 side, the second electrode 404 is formed of a material with high reflectivity. The second electrode 404 is connected to a pad 412 to supply a voltage.

[0400] As described above, the lighting device described in this embodiment has a light-emitting device including the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting device has high emission efficiency, the lighting device in this embodiment can have low power consumption.

[0401] The substrate 400 on which the light-emitting device having the above structure is formed and a sealing substrate 407 are fixed and sealed using sealing materials (405, 406), thereby completing the lighting device. Either one of the sealing materials 405 and 406 may be used. Also, a desiccant may be mixed into the inner sealing material 406 (not shown in FIG. 12(B)), which can adsorb moisture and improve reliability.

[0402] Moreover, the pad 412 and a part of the first electrode 401 can be extended outside the sealing materials 405 and 406 to serve as an external input terminal. Also, an IC chip 420 equipped with a converter or the like may be provided thereon.

[0403] (Embodiment 7) In this embodiment, an application example of a lighting device manufactured using a light-emitting device which is one embodiment of the present invention or a light-emitting device which is a part of the light-emitting device will be described with reference to FIGS.

[0404] As an indoor lighting device, it can be applied as a ceiling light 8001. The ceiling light 8001 is available in two types: a direct ceiling mount type and a ceiling recessed type. Such lighting devices are constructed by combining a light emitting device with a housing and a cover. It can also be applied to a cord pendant type (a type suspended from the ceiling by a cord).

[0405] The footlight 8002 can also irradiate light onto the floor surface to improve the safety of the feet. For example, it is effective to use it in bedrooms, stairs, and corridors. In that case, the size and shape can be changed appropriately according to the size and structure of the room. It is also possible to make a stationary lighting device consisting of a combination of a light-emitting device and a support stand.

[0406] The sheet-like lighting 8003 is a thin sheet-like lighting device. Since it is attached to a wall surface, it does not take up much space and can be used for a wide range of purposes. It is also easy to make it large-sized. It can also be used on curved walls, housings, etc.

[0407] It is also possible to use a lighting device 8004 in which light from a light source is controlled to only a desired direction.

[0408] The desk lamp 8005 includes a light source 8006, and as the light source 8006, a light-emitting device which is one embodiment of the present invention or a light-emitting device which is a part of the light-emitting device can be used.

[0409] In addition to the above, by applying the light-emitting device of one embodiment of the present invention or a light-emitting device that is a part of the light-emitting device to a piece of furniture installed in a room, the lighting device can have a function as the piece of furniture.

[0410] As described above, various lighting devices using the light-emitting device can be obtained. Note that these lighting devices are included in one embodiment of the present invention.

[0411] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiment modes.

[0412] (Embodiment 8) In this embodiment, a light-emitting device and a light-receiving device that can be used in a light-receiving and light-receiving device according to one embodiment of the present invention will be described with reference to FIGS.

[0413] FIG. 14A is a schematic cross-sectional view of a light-emitting device 805a and a light-receiving device 805b included in a light-receiving and light-emitting device 810 of one embodiment of the present invention.

[0414] The light-emitting device 805a has a function of emitting light (hereinafter, also referred to as a light-emitting function). The light-emitting device 805a has an electrode 801a, an EL layer 803a, and an electrode 802. The light-emitting device 805a is preferably a light-emitting device (organic EL device) using the organic EL shown in the second embodiment. Therefore, the EL layer 803a sandwiched between the electrode 801a and the electrode 802 has at least a light-emitting layer. The light-emitting layer has a light-emitting substance. Light is emitted from the EL layer 803a by applying a voltage between the electrode 801a and the electrode 802. The EL layer 803a may have various layers such as a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a carrier (hole or electron) blocking layer, and a charge generation layer in addition to the light-emitting layer.

[0415] The light receiving device 805b has a function of detecting light (hereinafter, also referred to as a light receiving function). For example, a pn-type or pin-type photodiode can be used for the light receiving device 805b. The light receiving device 805b has an electrode 801b, a light receiving layer 803b, and an electrode 802. The light receiving layer 803b sandwiched between the electrode 801b and the electrode 802 has at least an active layer. Note that the light receiving layer 803b can also use materials used for the various layers (hole injection layer, hole transport layer, light emitting layer, electron transport layer, electron injection layer, carrier (hole or electron) block layer, charge generation layer, etc.) of the above-mentioned EL layer 803a. The light receiving device 805b functions as a photoelectric conversion device, and can generate charges by light incident on the light receiving layer 803b and extract them as a current. At this time, a voltage may be applied between the electrode 801b and the electrode 802. The amount of generated charge is determined based on the amount of light incident on the light receiving layer 803b.

[0416] The light receiving device 805b has a function of detecting visible light. The light receiving device 805b is sensitive to visible light. It is more preferable that the light receiving device 805b has a function of detecting visible light and infrared light. It is preferable that the light receiving device 805b is sensitive to visible light and infrared light.

[0417] In this specification, the wavelength region of blue (B) is 400 nm or more and less than 490 nm, and blue (B) light has at least one emission spectrum peak in this wavelength region. In addition, the wavelength region of green (G) is 490 nm or more and less than 580 nm, and green (G) light has at least one emission spectrum peak in this wavelength region. In addition, the wavelength region of red (R) is 580 nm or more and less than 700 nm, and red (R) light has at least one emission spectrum peak in this wavelength region. In addition, in this specification, the wavelength region of visible light is 400 nm or more and less than 700 nm, and visible light has at least one emission spectrum peak in this wavelength region. In addition, the wavelength region of infrared (IR) is 700 nm or more and less than 900 nm, and infrared (IR) light has at least one emission spectrum peak in this wavelength region.

[0418] The active layer of the light-receiving device 805b includes a semiconductor. Examples of the semiconductor include an inorganic semiconductor such as silicon and an organic semiconductor including an organic compound. As the light-receiving device 805b, it is preferable to use an organic semiconductor device (or an organic photodiode) including an organic semiconductor in an active layer. The organic photodiode can be easily thinned, lightweight, and enlarged, and has a high degree of freedom in shape and design, and therefore can be applied to various display devices. In addition, by using an organic semiconductor, the EL layer 803a of the light-emitting device 805a and the light-receiving layer 803b of the light-receiving device 805b can be formed by the same method (for example, vacuum deposition), and a common manufacturing apparatus can be used, which is preferable. Note that the light-receiving layer 803b of the light-receiving device 805b can be formed using an organic compound which is one embodiment of the present invention.

[0419] In the display device of one embodiment of the present invention, an organic EL device is preferably used as the light-emitting device 805a, and an organic photodiode is preferably used as the light-receiving device 805b. The organic EL device and the organic photodiode can be formed over the same substrate. Therefore, the organic photodiode can be built into the display device using the organic EL device. The display device of one embodiment of the present invention has one or both of an imaging function and a sensing function in addition to a function of displaying an image.

[0420] The electrode 801a and the electrode 801b are provided on the same surface. Fig. 14A shows a structure in which the electrode 801a and the electrode 801b are provided on a substrate 800. Note that the electrode 801a and the electrode 801b can be formed, for example, by processing a conductive film formed on the substrate 800 into an island shape. That is, the electrode 801a and the electrode 801b can be formed through the same process.

[0421] The substrate 800 may be a substrate having heat resistance sufficient to withstand the formation of the light-emitting device 805a and the light-receiving device 805b. When an insulating substrate is used as the substrate 800, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like may be used. In addition, a semiconductor substrate such as a single crystal semiconductor substrate made of silicon or silicon carbide, a polycrystalline semiconductor substrate, a compound semiconductor substrate such as silicon germanium, or an SOI substrate may be used.

[0422] In particular, it is preferable to use a substrate in which a semiconductor circuit including a semiconductor element such as a transistor is formed on the aforementioned insulating substrate or semiconductor substrate as the substrate 800. The semiconductor circuit preferably constitutes, for example, a pixel circuit, a gate line driving circuit (gate driver), a source line driving circuit (source driver), etc. In addition to the above, an arithmetic circuit, a memory circuit, etc. may also be constituted.

[0423] The electrode 802 is an electrode made of a layer common to the light-emitting device 805a and the light-receiving device 805b. Of these electrodes, a conductive film that transmits visible light and infrared light is used for the electrode that emits light or that receives light. It is preferable to use a conductive film that reflects visible light and infrared light for the electrode that does not emit light or that does not receive light.

[0424] An electrode 802 in the display device according to one embodiment of the present invention functions as one electrode of each of a light-emitting device 805a and a light-receiving device 805b.

[0425] Fig. 14(B) shows a case where the electrode 801a of the light-emitting device 805a has a higher potential than the electrode 802. In this case, the electrode 801a functions as an anode of the light-emitting device 805a, and the electrode 802 functions as a cathode. The electrode 801b of the light-receiving device 805b has a lower potential than the electrode 802. In Fig. 14(B), in order to make it easier to understand the direction of current flow, the circuit symbol of a light-emitting diode is shown on the left side of the light-emitting device 805a, and the circuit symbol of a photodiode is shown on the right side of the light-receiving device 805b. The direction of carrier (electrons and holes) flow is also shown by arrows in each device.

[0426] In the case of the configuration shown in Figure 14(B), when a first potential is supplied to electrode 801a via a first wiring, a second potential is supplied to electrode 802 via a second wiring, and a third potential is supplied to electrode 801b via a third wiring, the relationship in magnitude of each potential is first potential>second potential>third potential.

[0427] 14(C) shows a case where the electrode 801a of the light-emitting device 805a has a lower potential than the electrode 802. At this time, the electrode 801a functions as the cathode of the light-emitting device 805a, and the electrode 802 functions as the anode. The electrode 801b of the light-receiving device 805b has a lower potential than the electrode 802 and a higher potential than the electrode 801a. In FIG. 14(C), in order to make it easier to understand the direction of current flow, the circuit symbol of a light-emitting diode is shown on the left side of the light-emitting device 805a, and the circuit symbol of a photodiode is shown on the right side of the light-receiving device 805b. The direction of carrier (electrons and holes) flow is also shown by arrows in each device.

[0428] In the case of the configuration shown in Figure 14(C), when a first potential is supplied to electrode 801a via a first wiring, a second potential is supplied to electrode 802 via a second wiring, and a third potential is supplied to electrode 801b via a third wiring, the relationship in magnitude of each potential is second potential>third potential>first potential.

[0429] Note that the resolution of the light-receiving device 805b described in this embodiment can be 100 ppi or more, preferably 200 ppi or more, more preferably 300 ppi or more, more preferably 400 ppi or more, and further preferably 500 ppi or more, and can be 2000 ppi or less, 1000 ppi or less, or 600 ppi or less. In particular, the light-receiving device 805b can be suitably used for imaging a fingerprint by disposing the light-receiving device 805b with a resolution of 200 ppi or more and 600 ppi or less, preferably 300 ppi or more and 600 ppi or less. When fingerprint authentication is performed using the display device of one embodiment of the present invention, by increasing the resolution of the light-receiving device 805b, for example, fingerprint minutia can be extracted with high accuracy, and the accuracy of fingerprint authentication can be improved. In addition, a resolution of 500 ppi or more is suitable because it can comply with standards such as those of the National Institute of Standards and Technology (NIST). Assuming that the resolution of the light receiving device is 500 ppi, the size of each pixel is 50.8 μm, which is sufficient resolution to capture an image of the width of a fingerprint (typically, 300 μm to 500 μm).

[0430] The structure described in this embodiment mode can be used in appropriate combination with structures described in other embodiment modes. EXAMPLES

[0431] In this example, light-emitting device 1 and light-emitting device 2 according to one embodiment of the present invention were fabricated, and the characteristics of the light-emitting devices were compared. The structural formulae of organic compounds used in light-emitting device 1 and light-emitting device 2 are shown below. The element structures of light-emitting device 1 and light-emitting device 2 are also shown.

[0432] [ka]

[0433] [Table 1]

[0434] <<Creating light-emitting device 1>> The light-emitting device 1 shown in this example has a structure in which a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer (a first electron transport layer and a second electron transport layer) and an electron injection layer are sequentially stacked on a first electrode formed on a substrate, a second electrode is stacked on the electron injection layer, and a cap layer is stacked on the second electrode.

[0435] First, a first electrode was formed on the substrate. The electrode area was 4 mm 2 (2 mm x 2 mm). A glass substrate was used as the substrate. The first electrode was formed by forming a film of silver with a thickness of 100 nm by sputtering, and then forming a film of indium tin oxide containing silicon oxide (ITSO) with a thickness of 10 nm as a transparent electrode by sputtering. In this embodiment, the first electrode functions as an anode.

[0436] As a pretreatment, the surface of the substrate was washed with water, baked at 200°C for 1 hour, and then subjected to UV ozone treatment for 370 seconds. -4 The substrate was introduced into a vacuum deposition apparatus whose inside had been reduced in pressure to about Pa, and vacuum baking was carried out at 170° C. for 30 minutes in a heating chamber in the vacuum deposition apparatus, and then the substrate was allowed to cool for about 30 minutes.

[0437] Next, a hole injection layer was formed on the first electrode. The hole injection layer was formed by evaporating 1×10 -4 After reducing the pressure to 10 Pa, N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF) and a fluorine-containing electron acceptor material (OCHD-003) with a molecular weight of 672 were co-evaporated to a thickness of 10 nm at a weight ratio of PCBBiF:OCHD-003 = 1:0.03.

[0438] Next, a hole transport layer was formed on the hole injection layer by vapor deposition of PCBBiF to a thickness of 15 nm.

[0439] Next, a light-emitting layer was formed on the hole transport layer. The light-emitting layer was formed using 8-(1,1':4',1"-terphenyl-3-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm, structural formula: (200)) as the first organic compound, 9-(2-naphthyl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: βNCCP) as the second organic compound, and [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN 2 A 40-nm thick film was formed by co-evaporation of 8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3)2(mbfpypy-d3) (weight ratio: 0.6:0.4:0.1) using [phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3), structural formula: (100)).

[0440] Next, an electron transport layer (first electron transport layer and second electron transport layer) was formed on the light-emitting layer. The first electron transport layer was formed by evaporating 2-{3-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq) to a thickness of 10 nm. The second electron transport layer was formed by evaporating 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P) to a thickness of 25 nm.

[0441] Next, lithium fluoride (LiF) and ytterbium (Yb) were co-deposited on the electron transport layer to a thickness of 1.5 nm so that the volume ratio of LiF:Yb was 2:1, thereby forming an electron injection layer.

[0442] Next, a second electrode was formed on the electron injection layer. The second electrode was formed by co-evaporating Ag and Mg in a volume ratio of 1:0.1 and a film thickness of 25 nm. In this example, the second electrode functions as a cathode.

[0443] Next, a cap layer was formed on the second electrode by vapor deposition of 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) to a thickness of 70 nm.

[0444] The above steps were used to produce the light-emitting device 1. Next, the methods for producing the light-emitting device 2 and the comparative light-emitting devices 4 to 8 will be described.

[0445] <<Creating light-emitting device 2>> Light-emitting device 2 is a light-emitting device in which a metal complex used in the light-emitting layer is different from that in light-emitting device 1. That is, light-emitting device 2 differs from light-emitting device 1 in that tris{2-[5-(methyl-d3)-4-phenyl-2-pyridinyl-κN]phenyl-κC}iridium(III) (abbreviation: Ir(5m4dppy-d3)3, structural formula: (106)) is used instead of Ir(5mppy-d3)2(mbfpypy-d3) used in the light-emitting layer of light-emitting device 1, and was otherwise fabricated in the same manner as light-emitting device 1.

[0446] The above-mentioned light-emitting device 1 and light-emitting device 2 were sealed with a glass substrate in a glove box with a nitrogen atmosphere to prevent them from being exposed to the atmosphere (a sealant was applied around the elements, and UV treatment was performed during sealing, and heat treatment was performed at 80°C for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0447] The luminance-current density characteristics of light-emitting device 1 and light-emitting device 2 are shown in Fig. 15, the current efficiency-luminance characteristics in Fig. 16, the luminance-voltage characteristics in Fig. 17, the current-voltage characteristics in Fig. 18, and the electroluminescence spectrum in Fig. 19. In addition, the 1000 cd / m 2The main characteristics in the vicinity are shown in Table 2. The luminance, CIE chromaticity, and electroluminescence spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0448] [Table 2]

[0449] 15 to 19 and the above table, it is apparent that the light emitting devices 1 and 2 have excellent characteristics.

[0450] In addition, in FIG. 20, the light-emitting device 1 and the light-emitting device 2 are subjected to a current of 2 mA (50 mA / cm 2 20 shows the change in luminance over drive time when a constant current drive was performed by applying a current of 1000 mA. As shown in FIG. 20, light-emitting device 1 and light-emitting device 2 show small changes in luminance over drive time, making them highly reliable light-emitting devices. Comparing light-emitting device 1 and light-emitting device 2, light-emitting device 2 shows an even smaller change in luminance over drive time and is more reliable.

[0451] These results show that the light-emitting device according to one embodiment of the present invention has favorable characteristics and a long lifetime. EXAMPLES

[0452] In this example, a light-emitting device 3 according to one embodiment of the present invention and comparative light-emitting devices 4 to 8 having different light-emitting layer configurations from those of the light-emitting device 3 were fabricated, and the results of comparing the characteristics of each light-emitting device are shown. Structural formulas of organic compounds used in the light-emitting device 3 and the comparative light-emitting devices 4 to 8 are shown below. Tables 3 and 4 show the element structures of the light-emitting device 3 and the comparative light-emitting devices 4 to 8.

[0453] [ka]

[0454] [Table 3]

[0455] [Table 4]

[0456] <<Creating light-emitting device 3>> The light-emitting device 3 shown in this example is a light-emitting device different from the light-emitting device 1 shown in Example 1 in the mixing ratio of the first organic compound, the second organic compound, and the metal complex in the light-emitting layer and the film thickness of the second electron transport layer. That is, the light-emitting device 3 differs from the light-emitting device 1 in that the mixing ratio of 8mpTP-4mDBtPBfpm, βNCCP, and Ir(5mppy-d3)2(mbfpypy-d3) in the light-emitting layer was 8mpTP-4mDBtPBfpm:βNCCP:Ir(5mppy-d3)2(mbfpypy-d3)=0.5:0.5:0.1 by weight and the film thickness of the second electron transport layer was 20 nm, but was otherwise fabricated in the same manner as the light-emitting device 1.

[0457] <Preparation of Comparative Light-Emitting Device 4 to Comparative Light-Emitting Device 8> Comparative light-emitting device 4 to comparative light-emitting device 8 are light-emitting devices different from light-emitting device 3 in either or both of the first organic compound and the metal complex in the light-emitting layer. Other configurations of comparative light-emitting device 4 to comparative light-emitting device 8 were prepared in the same manner as light-emitting device 3.

[0458] As the first organic compound, 8mpTP-4mDBtPBfpm was used in the comparative light-emitting device 4 as in the light-emitting device 3, 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm) was used in the comparative light-emitting devices 5 and 6, and 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm) was used in the comparative light-emitting devices 7 and 8.

[0459] As the metal complex, Ir(5mppy-d3)2(mbfpypy-d3) was used in Comparative Light-Emitting Device 5 and Comparative Light-Emitting Device 7, as in Light-Emitting Device 3, and [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)) was used in Comparative Light-Emitting Device 4, Comparative Light-Emitting Device 6, and Comparative Light-Emitting Device 8.

[0460] The above-mentioned light-emitting device 3 and comparative light-emitting device 4 to comparative light-emitting device 8 were sealed with a glass substrate in a glove box with a nitrogen atmosphere to prevent exposure to the atmosphere (a sealant was applied around the elements, and UV treatment was performed during sealing, and heat treatment was performed at 80°C for 1 hour), and then the initial characteristics of these light-emitting devices were measured.

[0461] FIG. 21 shows the luminance-current density characteristics of the light-emitting device 3 and the comparative light-emitting device 4 to the comparative light-emitting device 6, FIG. 22 shows the current efficiency-luminance characteristics, FIG. 23 shows the luminance-voltage characteristics, FIG. 24 shows the current-voltage characteristics, and FIG. 25 shows the electroluminescence spectra. FIG. 26 shows the luminance-current density characteristics of the light-emitting device 3, the comparative light-emitting device 4, the comparative light-emitting device 7, and the comparative light-emitting device 8, FIG. 27 shows the current efficiency-luminance characteristics, FIG. 28 shows the luminance-voltage characteristics, FIG. 29 shows the current-voltage characteristics, and FIG. 30 shows the electroluminescence spectra. The light-emitting device 3 and the comparative light-emitting device 4 used to measure the characteristics shown in FIGS. 21 to 25 are different samples from the light-emitting device 3 and the comparative light-emitting device 4 used to measure the characteristics shown in FIGS. 26 to 30, although they have the same structure. Therefore, the characteristics of the light-emitting device 3 and the comparative light-emitting device 4 shown in FIGS. 21 to 25 are not exactly the same as the characteristics of the light-emitting device 3 and the comparative light-emitting device 4 shown in FIGS. 26 to 30.

[0462] In addition, each light-emitting device has a 1000cd / m 2 The main characteristics in the vicinity are shown in Table 5. The luminance, CIE chromaticity, and electroluminescence spectrum were measured using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0463] [Table 5]

[0464] 21 to 30 show that the light-emitting device 3, the comparative light-emitting device 5, and the comparative light-emitting device 7 have lower driving voltages and higher current efficiencies than the comparative light-emitting device 4, the comparative light-emitting device 6, and the comparative light-emitting device 8. This shows that the use of Ir(5mppy-d3)2(mbfpypy-d3) as the metal complex in the light-emitting layer can reduce the driving voltage and improve the current efficiency.

[0465] This is because Ir(5mppy-d3)2(mbfpypy-d3) is a metal complex that has a deuterated methyl group, which is an electron donating group, on the pyridine ring of the ligand, and therefore has a higher (shallower) HOMO level than Ir(ppy)2(mbfpypy-d3), which has no substituent on the pyridine ring of the ligand. By increasing the HOMO level of the metal complex, the hole injection barrier at the interface between the hole transport layer and the light emitting layer becomes smaller, and as a result, the driving voltage of the light emitting device 3 can be reduced and the current efficiency can be improved.

[0466] The HOMO levels of Ir(5mppy-d3)2(mbfpypy-d3) and Ir(ppy)2(mbfpypy-d3) were calculated by cyclic voltammetry (CV) measurements. An electrochemical analyzer (manufactured by BAS Co., Ltd., model number: ALS model 600A or 600C) was used for the measurements. As a result, the HOMO level of Ir(5mppy-d3)2(mbfpypy-d3) was -5.32 eV, and the HOMO level of Ir(ppy)2(mbfpypy-d3) was -5.36 eV, and Ir(5mppy-d3)2(mbfpypy-d3) has a higher HOMO level than Ir(ppy)2(mbfpypy-d3).

[0467] 31 and 32, the light-emitting device 3 and the comparative light-emitting devices 4 to 8 were subjected to a current of 2 mA (50 mA / cm 2 31 shows the results of light-emitting device 3 and comparative light-emitting device 4 to comparative light-emitting device 6, and FIG. 32 shows the results of light-emitting device 3 and comparative light-emitting device 4, comparative light-emitting device 7, and comparative light-emitting device 8.

[0468] 31 and 32, it was found that light-emitting device 3 had the smallest change in luminance over operating time and was the most reliable light-emitting device compared to the comparative light-emitting devices. This shows that by using 8mpTP-4mDBtPBfpm as the first organic compound and Ir(5mppy-d3)2(mbfpypy-d3) as the metal complex, it is possible to reduce the change in luminance over operating time of the light-emitting device and improve its reliability.

[0469] This is because the lowest triplet excitation of 8mpTP-4mDBtPBfpm originates from the terphenyl group. The T1 level when the terphenyl group is excited can be made lower than the T1 levels when other partial structures are excited, so the use of 8mpTP-4mDBtPBfpm can improve the reliability of light-emitting devices.

[0470] Next, the T1 level of 8mpTP-4mDBtPBfpm was calculated. A thin film of 8mpTP-4mDBtPBfpm was formed on a quartz substrate to a thickness of 50 nm, and the emission spectrum (phosphorescence spectrum) was measured at a measurement temperature of 10 K. The measurement was performed using a micro PL device LabRAM HR-PL (Horiba, Ltd.) and a He-Cd laser (325 nm) as the excitation light. As a result, the peak located at the shortest wavelength of the emission spectrum (phosphorescence spectrum) of 8mpTP-4mDBtPBfpm was 500 nm (2.48 eV), and the emission edge located at the shortest wavelength was 486 nm (2.55 eV).

[0471] In addition, the absorption spectrum and emission spectrum (phosphorescence spectrum) were measured to calculate the T1 level of Ir(5mppy-d3)2(mbfpypy-d3). A toluene solution was prepared by dissolving Ir(5mppy-d3)2(mbfpypy-d3), and the absorption spectrum and emission spectrum were measured at room temperature (atmosphere maintained at 23°C). As a result, the absorption edge located at the longest wavelength in the absorption spectrum of Ir(5mppy-d3)2(mbfpypy-d3) was 526 nm (2.36 eV), and the emission edge located at the shortest wavelength in the emission spectrum (phosphorescence spectrum) was 503 nm (2.46 eV).

[0472] The absorption edge was calculated by drawing a tangent at the value where the slope on the long wavelength side of the peak (or shoulder peak) observed at the longest wavelength in the absorption spectrum is the smallest, and then calculating from the intersection of the tangent with the horizontal axis (wavelength) or the baseline. The emission edge was calculated by drawing a tangent at the value where the slope on the short wavelength side of the peak (or shoulder peak) observed at the shortest wavelength in the emission spectrum is the largest, and then calculating from the intersection of the tangent with the horizontal axis (wavelength) or the baseline.

[0473] Comparing the T1 levels calculated at the emission edge of 8mpTP-4mDBtPBfpm and Ir(5mppy-d3)2(mbfpypy-d3), the lowest triplet excitation energy of 8mpTP-4mDBtPBfpm is 0.09 eV higher than the lowest triplet excitation energy of Ir(5mppy-d3)2(mbfpypy-d3).

[0474] In addition, Ir(5mppy-d3)2(mbfpypy-d3) has a deuterated methyl group on the pyridine ring of the ligand, so the hydrogen-carbon bond in the methyl group is less likely to break due to vibration, making it a more stable metal complex than a ligand with a non-deuterated methyl group on the pyridine ring. The high stability and reliability of this metal complex has led to improved reliability of light-emitting devices. EXAMPLES

[0475] In this example, the results of analysis by calculation of a first organic compound that can be used in a light-emitting device of one embodiment of the present invention will be described with reference to FIGS.

[0476] The HOMO distribution, LUMO distribution, and localization of the lowest triplet excited state were analyzed for 8mpTP-4mDBtPBfpm (structural formula (200)), which is one specific example of the first organic compound, the organic compound represented by structural formula (216), and 8BP-4mDBtPBfpm, which is a comparative example.

[0477] [ka]

[0478] <Calculation method> The analysis of the distribution of HOMO and LUMO was performed by vibration (spin density) analysis of the most stable structure with the lowest S0 level for the singlet ground state (S0) of the compound. The analysis of the localization of the lowest triplet excited state was performed by spin density analysis of the most stable structure with the lowest T1 level for the lowest triplet excited state (T1) of the compound. The calculation method used was density functional theory (DFT). The total energy calculated by DFT is expressed as the sum of potential energy, electrostatic energy between electrons, kinetic energy of electrons, and exchange-correlation energy including all complex interactions between electrons. In DFT, the exchange-correlation interaction is approximated by a functional (meaning a function of a function) of a single-electron potential expressed by electron density, so the calculation is fast. Here, the weight of each parameter related to the exchange-correlation energy was specified using the mixed functional B3LYP. In addition, 6-311G(d,p) was used as the basis function. Gaussian 09 was used as the calculation program.

[0479] The analysis results of 8mpTP-4mDBtPBfpm are shown in FIG. 33, the analysis results of the organic compound represented by the structural formula (216) are shown in FIG. 34, and the analysis results of 8BP-4mDBtPBfpm are shown in FIG. 35. In FIG. 33 to FIG. 35, the spheres in the figures represent the atoms constituting the compound, and the clouds around the atoms represent the spin density distribution when the spin density value is set to 0.003. In FIG. 33(A), FIG. 34(A), and FIG. 35(A), the clouds represent the distribution of the LUMO in the molecule. In FIG. 33(B), FIG. 34(B), and FIG. 35(B), the clouds represent the distribution of the HOMO in the molecule. In FIG. 33(C), FIG. 34(C), and FIG. 35(C), the clouds represent the localization of the lowest triplet excited state in the molecule.

[0480] 33 and 34, in 8mpTP-4mDBtPBfpm and the organic compound represented by structural formula (216), the lowest triplet excited state is localized in the terphenyl group corresponding to the first substituent of the first organic compound, and the LUMO is distributed in the [1]benzofuro[3,2-d]pyrimidine ring corresponding to the electron transport skeleton and in a part of the 3-(dibenzothiophene-4-yl)phenyl group corresponding to the second substituent. Therefore, in 8mpTP-4mDBtPBfpm and the organic compound represented by structural formula (216), the position where the LUMO is distributed and the position where the lowest triplet excited state is localized are different from each other.

[0481] On the other hand, from Figure 35, the lowest triplet excited state of 8BP-4mDBtPBfpm is distributed not only in the 1,1'-biphenyl-4-yl group corresponding to the first substituent of the first organic compound, but also in the [1]benzofuro[3,2-d]pyrimidine ring corresponding to the electron transport skeleton, and the LUMO is distributed in the [1]benzofuro[3,2-d]pyrimidine ring corresponding to the electron transport skeleton and in part of the 3-(dibenzothiophene-4-yl)phenyl group corresponding to the second substituent. Therefore, in 8BP-4mDBtPBfpm, it was found that the position where the lowest triplet excited state is localized and the distribution position of the LUMO overlap.

[0482] From the above results, as described in the first embodiment, it was found that the lowest triplet excited state can be distributed to the first substituent by making the first substituent of the first organic compound a group in which either a substituted or unsubstituted aromatic ring or a substituted or unsubstituted heteroaromatic ring is linked to either a substituted or unsubstituted o-phenylene group or a substituted or unsubstituted m-phenylene group. EXAMPLES

[0483] In this example, a 2-methyltetrahydrofuran (2Me-THF) solution of an organic compound that can be used as the first organic compound was cooled with liquid nitrogen, and the emission spectrum and emission quantum yield were measured.

[0484] First, 8mpTP-4mDBtPBfpm (structural formula (200)) and 8-(1,1':4',1''-terphenyl-3-yl-2,4,5,6,2',3',5',6',2'',3'',4'',5'',6''-d 13 )-4-[3-(dibenzothiophen-4-yl-1,2,3,6,7,8,9-d7)phenyl-2,4,6-d3]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm-d 23 ) (Structural formula (219)) was used as a sample for the measurement. The T1 level of 8mpTP-4mDBtPBfpm-d 23 The T1 level was measured and found to be 8mpTP-4mDBtPBfpm-d 23 The peak located at the shortest wavelength in the emission spectrum (phosphorescence spectrum) was 501 nm (2.48 eV), and the emission edge located at the shortest wavelength was 484 nm (2.56 eV).

[0485] [ka]

[0486] The emission spectra and emission quantum yields were measured using an absolute PL quantum yield measurement device (C11347-01, manufactured by Hamamatsu Photonics K.K.) and in a glove box (LABstarM13(1250 / 780), manufactured by Bright Inc.), the deoxygenated 2Me-THF solution (0.120 mmol / L) of each sample was placed in a quartz cell under a nitrogen atmosphere, sealed, and cooled with liquid nitrogen.

[0487] 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d 23 The measurement results of the emission spectrum are shown in Figure 36. The horizontal axis represents the wavelength, and the vertical axis represents the emission intensity.

[0488] As shown in Figure 36, the emission spectrum of a mixture of fluorescence and phosphorescence was observed in all samples. The spectrum around 351 nm to 455 nm was confirmed to be fluorescence based on the room temperature measurement and the emission lifetime measurement results. In addition, the spectrum around 455 nm to 660 nm was confirmed to be derived from phosphorescence because it was only observed in the low temperature measurement.

[0489] In addition, the measurement results of the luminescence quantum yield showed that the quantum yield (Φ f The quantum yield (Φ p (H)) was found to be 10%.

[0490] In addition, the emission quantum yield measurement results showed that 8mpTP-4mDBtPBfpm-d 23 The quantum yield (Φ f The quantum yield (Φ p (D)) was found to be 15%.

[0491] That is, at low temperatures (temperatures cooled with liquid nitrogen), 8mpTP-4mDBtPBfpm-d 23 It was found that the quantum yield of the phosphorescent component of was 1.5 times that of the phosphorescent component of 8mpTP-4mDBtPBfpm, and the quantum yield of the fluorescent component was almost the same.

[0492] Also, 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm-d 23 The results of measuring the luminescence lifetime of each 2Me-THF solution (0.120 mmol / L) cooled with liquid nitrogen are shown.

[0493] A fluorometer (FP-8600, manufactured by JASCO Corp.) was used to measure the luminescence lifetime. The sample solution was placed in a quartz cell in the atmosphere and cooled with liquid nitrogen for measurement. In this measurement, the wavelength of the excitation light was 320 nm and the wavelength of the measurement light was 515 nm. The excitation light was irradiated onto the quartz cell containing the solution for about 30 seconds, and the excitation light was blocked with a shutter, after which the decaying luminescence intensity was measured at 10 ms intervals for time-resolved measurement. The bandwidth of the excitation light and measurement light was 10 nm. The obtained time decay curve is shown in Figure 39. The horizontal axis represents time, and the vertical axis represents luminescence intensity.

[0494] As shown in Figure 39, the luminescence intensity was found to decay in a single exponential manner. The luminescence lifetime was calculated from the resulting decay curve. The luminescence lifetime of 8mpTP-4mDBtPBfpm was 2.8 s. 23 The luminescence lifetime of was 5.3 s. Since the wavelength of the light used to measure the luminescence lifetime was 515 nm, it can be said that these are the luminescence lifetimes of the phosphorescent components. Therefore, it was found that at low temperatures (temperatures cooled with liquid nitrogen), the phosphorescence lifetime of the deuterated material is 1.9 times longer than that of the non-deuterated material.

[0495] Here, the phosphorescence quantum yield (Φ p ) and phosphorescence lifetime (τ p ) is the radiative transition rate constant k from the lowest triplet excited state (T1) of an organic compound rpand the nonradiative transition rate constant k nrp , and the quantum yield of intersystem crossing from the lowest singlet excited state (S1) to the lowest triplet excited state (T1) (Φ isc ) can be expressed as the following equations (1) and (2).

[0496]

number

[0497] From this formula, k rp and k nrp can be expressed using Φ and τ as the following equations (3) and (4), respectively.

[0498]

number

[0499] Here, from the above measurement results, deuterated 8mpTP-4mDBtPBfpm-d 23 Phosphorescence quantum yield Φ p (D) The phosphorescence quantum yield Φ of undeuterated 8mpTP-4mDBtPBfpm p 1.5 times larger than (H), 8mpTP-4mDBtPBfpm-d 23 Phosphorescence lifetime τ p (D) The phosphorescence lifetime τ of 8mpTP-4mDBtPBfpm p It is known that the value is 1.9 times that of (H). 23 Fluorescence quantum yield Φ f (D) and the fluorescence quantum yield Φ of 8mpTP-4mDBtPBfpm f (H) was almost the same.

[0500] At the temperature cooled by liquid nitrogen, the rate constant of the nonradiative transition of fluorescence is much smaller than the rate constants of the radiative transition and intersystem crossing. 23 The quantum yield Φ of intersystem crossing isc (H) and Φisc (D) shows the fluorescence quantum yield (Φ f (H), Φ f Using (D), Φ isc (H)=1-Φ f (H) Φ isc (D)=1-Φ f (D) and Φ f (H) and Φ f (D) was almost the same value, so Φ isc (H) and Φ isc (D) can be considered the same.

[0501] That is, the phosphorescence quantum yield of 8mpTP-4mDBtPBfpm is Φ p (H), the rate constant is τ p (H), the quantum yield of intersystem crossing is Φ isc (H), the rate constant of the radiative transition is k rp (H), the rate constant of the nonradiative transition is k nrp (H) 8mpTP-4mDBtPBfpm-d 23 The phosphorescence quantum yield of Φ p (D) The rate constant is τ p (D) The quantum yield of intersystem crossing is Φ isc (D) The rate constant of the radiative transition is k rp (D) The rate constant of the nonradiative transition is k nrp (D) Then, k rp (H) is the following formula (3-1), k rp (D) is the following formula (3-2), k nrp (H) is the following formula (4-1), k nrp (D) can be expressed as the following equation (4-2).

[0502]

number

[0503] In this way, k nrp (D) is k nrp (H) is 0.50 times, k nrp (D) <k nrp(H) and k rp (D) is k rp (H) is 0.79 times, k rp (D) <k rp (H), and compared to 8mpTP-4mDBtPBfpm, the deuterated 8mpTP-4mDBtPBfpm-d 23 It was found that both the rate constants of the nonradiative transition and the radiative transition are small, but since the rate constant of the nonradiative transition is smaller than the rate constant of the radiative transition, it was found that the nonradiative transition is more suppressed than the radiative transition.

[0504] In this way, the deuterated organic compound has smaller rate constants for radiative transition and non-radiative transition, but the non-radiative transition is more suppressed, so that the generated triplet excitons can undergo radiative transition in a larger number. Since the radiative transition is a transition related to energy transfer, the deuterated organic compound has improved energy transfer efficiency for transferring the excitation energy to another compound (here, the phosphorescent material, which is the guest material) compared to the non-deuterated organic compound. The improved energy transfer efficiency makes it possible to suppress the deterioration of the deuterated organic compound, and a light-emitting device using the organic compound as a host material can be a light-emitting device with good reliability because the deterioration of the host material is suppressed.

[0505] At low temperatures (temperatures cooled with liquid nitrogen), 23 The rate constant k for the radiative transition of rp (D) is the rate constant k of the radiative transition of 8mpTP-4mDBtPBfpm rp (H), but the nonradiative transition rate constant k nrp (D) is k nrp (H), the rate constant of the nonradiative transition is relatively low, k nrp The decrease in (D) is larger. Therefore, the rate constant of the radiative transition k rp Even considering the decrease in (D), 8mpTP-4mDBtPBfpm-d 23Since the proportion of triplet excitons that undergo radiative transition increases in the nucleon, it can be said that deuteration improves the efficiency of energy transfer.

[0506] In addition, the fluorescence quantum yield was 8mpTP-4mDBtPBfpm-d 23 There was almost no difference between 8mpTP-4mDBtPBfpm and 8mpTP-4mDBtPBfpm. In addition, the rate constant of the non-radiative transition at the low temperature of 77K is very small compared to the rate constants of the radiative transition and intersystem crossing. This suggests that deuteration of 8mpTP-4mDBtPBfpm-d 23 There was no significant difference in the rate constants of the radiative and nonradiative transitions in the fluorescence emission process of 8mpTP-4mDBtPBfpm, and it can be said that the effect of deuteration mainly affects the behavior of triplet excitons.

[0507] Here, 8mpTP-4mDBtPBfpm-d, in which only the first substituent of 8mpTP-4mDBtPBfpm was replaced with deuterium, is 13 (Structural formula (223)) and 8mpTP-4mDBtPBfpm-d, in which only the second substituent is deuterium-substituted. 10 (Structural formula (225)) was similarly measured.

[0508] [ka]

[0509] 8mpTP-4mDBtPBfpm-d 13 The emission spectrum measurement results are shown in Figure 37. 10 The measurement results of the emission spectrum are shown in Figure 38. The horizontal axis represents the wavelength, and the vertical axis represents the emission intensity.

[0510] As shown in Figure 37 and Figure 38, 8mpTP-4mDBtPBfpm-d 13 (Structural formula (223)) is 8mpTP-4mDBtPBfpm-d 23 Equivalent to 8mpTP-4mDBtPBfpm-d 10(Structural formula (225)) gave results equivalent to those of 8mpTP-4mDBtPBfpm.

[0511] 8mpTP-4mDBtPBfpm-d 23 The results were equivalent to 8mpTP-4mDBtPBfpm-d 13 is an organic compound in which only the first substituent of the first organic compound is replaced with deuterium. Therefore, it has been revealed that the first organic compound can suppress the non-radiative transition in the phosphorescence process by replacing only the first substituent with deuterium. This is because T1 is localized in the first substituent in the first organic compound, and by deuterizing the first substituent, the intramolecular vibration in the lowest triplet excited state is suppressed, which makes it possible to suppress the non-radiative transition from T1 of the first organic compound.

[0512] In addition, the energy transfer efficiency from the host material to the guest material, φ ET From the viewpoint of energy transfer efficiency φ ET is expressed by the following formula (5), and the energy transfer efficiency φ ET To increase the rate constant of energy transfer, k h*→g becomes large and other competing rate constants k r +k nr It can be seen that it is good if (=1 / τ) becomes relatively small.

[0513] In addition, in formula (5), k r represents the rate constant of the light emission process of the host material (fluorescence when energy transfer from a singlet excited state is considered, and phosphorescence when energy transfer from a triplet excited state is considered), and k nr represents the rate constant of the non-radiative processes (thermal deactivation and intersystem crossing) of the host material, and τ represents the lifetime of the excited state of the host material measured. h*→g represents the rate constant for energy transfer (Förster or Dexter mechanism).

[0514]

number

[0515] Energy transfer rate constant k h*→g is a deuterated organic compound (8mpTP-4mDBtPBfpm-d 23 In the case of an organic compound (8mpTP-4mDBtPBfpm) that is not deuterated, the atomic arrangement of the molecules and the spectral shape are almost the same, so the two materials are almost identical (see formula (6) or (7) below). Therefore, when comparing deuterated organic compounds with non-deuterated organic compounds, it can be seen that the luminescence lifetime (phosphorescence lifetime) τ has a large effect.

[0516] As mentioned above, the phosphorescence lifetime measured at low temperatures (temperatures cooled with liquid nitrogen) is consistent with that of deuterated organic compounds (8mpTP-4mDBtPBfpm-d 23 Assuming that there is a difference in phosphorescence lifetime between deuterated and non-deuterated organic compounds even at room temperature, the energy transfer efficiency from the host material to the guest material, φ ET From formula (5), the deuterated organic compound (8mpTP-4mDBtPBfpm-d 23 It can be said that a light-emitting device using the organic compound (8mpTP-4mDBtPBfpm) as a host material has improved energy transfer efficiency compared to a light-emitting device using an organic compound (8mpTP-4mDBtPBfpm) that is not used as a host material.

[0517] The improvement in the energy transfer efficiency makes it possible to suppress the deterioration of the deuterated organic compound, and therefore, a light-emitting device using a deuterated organic compound as a host material can be made to have a higher reliability because the deterioration of the host material is suppressed compared to a light-emitting device using a non-deuterated organic compound as the host material.

[0518]

number

[0519]

number

[0520] Equation (6) is the rate constant k for the Förster mechanism, and equation (7) is the rate constant k for the Dexter mechanism. h*→g This is the formula.

[0521] In formula (6), ν represents the frequency, and f' h (ν) represents the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state), and ε g (ν) represents the molar absorption coefficient of the guest material, N represents Avogadro's number, n represents the refractive index of the medium, R represents the intermolecular distance between the host material and the guest material, τ represents the lifetime of the excited state (fluorescence lifetime or phosphorescence lifetime) actually measured, φ represents the luminescence quantum yield (fluorescence quantum yield when discussing energy transfer from a singlet excited state, and phosphorescence quantum yield when discussing energy transfer from a triplet excited state), and K 2 is a coefficient (0 to 4) that represents the orientation of the transition dipole moment of the host material and the guest material. In the case of random orientation, K 2 =2 / 3.

[0522] In formula (7), h is the Planck constant, K is a constant having the dimension of energy, ν is the frequency, and f' h (ν) represents the normalized emission spectrum of the host material (fluorescence spectrum when discussing energy transfer from a singlet excited state, and phosphorescence spectrum when discussing energy transfer from a triplet excited state), and ε' g (ν) represents the normalized absorption spectrum of the guest material, L represents the effective molecular radius, and R represents the intermolecular distance between the host material and the guest material.

[0523] In addition, when the energy of triplet excitons is high, the long lifetime of the excitons may accelerate deterioration. However, in one embodiment of the present invention, since the first organic compound is a material with a relatively low T1 level, the effect of the long lifetime of triplet excitons on reliability is small. Furthermore, it has been found that a substance in which the first and second substituents in the first organic compound (host material) are deuterated suppresses non-radiative transitions, thereby increasing the efficiency of energy transfer from the substance to the light-emitting material and improving the reliability of the light-emitting device. EXAMPLES

[0524] In this example, light-emitting device 9 and light-emitting device 10, which are light-emitting devices according to one embodiment of the present invention, were fabricated, and the characteristics of the light-emitting devices were compared. Structural formulas of organic compounds used in light-emitting device 9 and light-emitting device 10 are shown below. Table 6 shows the element structures of light-emitting device 9 and light-emitting device 10.

[0525] [ka]

[0526] [Table 6]

[0527] "Creating Light-Emitting Device 9" Light-emitting device 9 is a light-emitting device in which the thickness of the second electron transport layer is different from that of light-emitting device 3 shown in Example 2. That is, light-emitting device 9 differs from light-emitting device 3 in that the thickness of the second electron transport layer is 10 nm, and was otherwise fabricated in the same manner as light-emitting device 3.

[0528] "Fabrication of Light-Emitting Device 10" The light-emitting device 10 is a light-emitting device in which 8mpTP-4mDBtPBfpm, which was used as the first organic compound of the light-emitting layer in the light-emitting device 9, is replaced with 8mpTP-4mDBtPBfpm-d 23The other parts were fabricated in the same manner as for light-emitting device 9.

[0529] The luminance-current density characteristics of the light-emitting device 9 and the light-emitting device 10 are shown in FIG. 40, the current efficiency-luminance characteristics in FIG. 41, the luminance-voltage characteristics in FIG. 42, the current-voltage characteristics in FIG. 43, and the emission spectrum in FIG. 44. 2 The values ​​of voltage, current, current density, CIE chromaticity, and current efficiency in the vicinity are shown below. The luminance, CIE chromaticity, and emission spectrum were measured at room temperature using a spectroradiometer (SR-UL1R, manufactured by Topcon Corporation).

[0530] [Table 7]

[0531] 40 to 44, it is apparent that both the light emitting device 9 and the light emitting device 10 are light emitting devices having excellent characteristics.

[0532] Next, the current density of the light-emitting device 9 and the light-emitting device 10 was 50 mA / cm 2 The change in luminance versus drive time during constant current drive was measured and the results are shown in Fig. 45. Fig. 45 shows that both light-emitting device 9 and light-emitting device 10 are light-emitting devices with good reliability.

[0533] Furthermore, it was found that the light-emitting device 10 has a longer lifetime than the light-emitting device 9. That is, 8mpTP-4mDBtPBfpm-d, in which the first and second substituents of the first organic compound are deuterated, 23 It was found that the light-emitting device using 8mpTP-4mDBtPBfpm had improved reliability compared to the light-emitting device using the non-deuterated 8mpTP-4mDBtPBfpm. As shown in Example 4, this is because the substance in which the first and second substituents in the first organic compound (host material) are deuterated suppresses non-radiative transitions, increasing the efficiency of energy transfer from the substance to the light-emitting material, thereby improving the reliability of the light-emitting device. [Explanation of symbols]

[0534] GD Circuit IR subpixel MS Wiring PS Subpixel REG Resist mask RES wiring SE1 Wiring SE Distance TX wiring VG wiring VS wiring 101 First electrode 102 Second electrode 103 EL layer 103a EL layer 103b EL layer 103B EL layer 103G EL layer 103R EL layer 103PS Photoreceptor layer 104B Hole injection / transport layer 104G Hole injection / transport layer 104R Hole injection / transport layer 104PS Hole injection / transport layer 105 Light-emitting layer 105B Light-emitting layer 105G Light-emitting layer 105R Light-emitting layer 105PS active layer 106 Charge generation layer 106a Charge generating layer 106b Charge generating layer 107 Insulating layer 108 Electron transport layer 108B Electron transport layer 108G electron transport layer 108R Electron transport layer 108PS electron transport layer 109 Electron injection layer 110B Sacrificial layer 110G sacrificial layer 110R Sacrificial layer 110PS sacrificial layer 111 Hole injection layer 111a Hole injection layer 111b Hole injection layer 112 Hole transport layer 112a Hole transport layer 112b Hole transport layer 113 Light-emitting layer 113a Light-emitting layer 113b Light-emitting layer 113c Emitting layer 114 Electron transport layer 114a Electron transport layer 114b Electron transport layer 115 Electron injection layer 115a Electron injection layer 115b Electron injection layer 130 Connection 400 Substrates 401 First electrode 403 EL layer 404 Second electrode 405 Sealing material 406 Sealing material 407 Sealing substrate 412 Pad 420 IC chip 501C Insulating film 501D Insulating film 504 Conductive film 506 Insulating film 508 Semiconductor Film 508A area 508B area 508C area 510 First substrate 512A Conductive film 512B Conductive film 516 Insulating film 516A Insulating film 516B Insulating film 518 Insulating film 520 Functional Layer 524 Conductive Film 528 Bulkhead 528a Resin film 530S pixel circuit 530X pixel circuit 550 Light Emitting Device 550X Light Emitting Device 550S Light receiving device 550B Light Emitting Device 550G Light Emitting Device 550R Light Emitting Device 550PS light receiving device 551 Electrode 551B Electrode 551C Connection electrode 551G electrode 551R electrode 551PS electrode 552 Electrode 580 Gap 591S Wiring 591X Wiring 700 Light receiving and emitting device 701 Display area 702G subpixel 702PS subpixel 702R Subpixel 702IR subpixels 702B Subpixel 703 pixels 704 Circuit 705 Insulation Layer 706 Wiring 710 Substrate 711 Substrate 712 IC 713 FPC 720 equipment 770 Substrate 800 boards 801a electrode 801b electrode 802 Electrode 803a EL layer 803b Photosensitive layer 805a Light Emitting Device 805b Light receiving device 810 Light receiving and emitting device 5200B Electronic equipment 5210 Arithmetic unit 5220 I / O device 5230 Display section 5240 Input Unit 5250 Detector 5290 Communications Department 8001 Ceiling Light 8002 Footlight 8003 Sheet lighting 8004 Lighting equipment 8005 Desk lamp 8006 light source

Claims

1. It has an anode, a cathode, and a light-emitting layer, The light-emitting layer is located between the anode and the cathode. The light-emitting layer comprises a light-emitting material and a first organic compound, The luminescent material is an organometallic complex having a central metal and a ligand. At least one of the ligands is ring A １ It has a skeleton in which a pyridine ring and are bonded, Ring A １ This represents an aromatic ring or a heteroaromatic ring. The pyridine ring has a deuterium-substituted alkyl group having 1 to 6 carbon atoms. The ligand is the ring A １ Any atom of and the nitrogen of the pyridine ring coordinate to the central metal, The first organic compound comprises an electron-transporting skeleton, a first substituent bonded to the electron-transporting skeleton, and a second substituent, The electron-transporting skeleton has a heteroaromatic ring having two or more nitrogen atoms, The first substituent is a group having one or both an aromatic ring and / or a heteroaromatic ring. The second substituent has a hole-transporting skeleton, A light-emitting device in which the lowest triplet excited state of the first organic compound is localized to the first substituent.

2. It has an anode, a cathode, and a light-emitting layer, The light-emitting layer is located between the anode and the cathode. The light-emitting layer comprises a light-emitting material and a first organic compound, The luminescent material is an organometallic complex having a central metal and a ligand. At least one of the ligands has a structure represented by the general formula (L1), The first organic compound is an organic compound represented by general formula (G10), and the device is a light-emitting device. 【Chemistry 1】 (However, in General Formula (L1), * represents a bond to the central metal, the dashed line represents coordination to the central metal, and Ring A １ represents an aromatic ring or a heteroaromatic ring, and R １ to R ４ at least one of which is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and an aryl group having 6 to 13 carbon atoms that forms a substituted or unsubstituted ring. Also, in General Formula (G10), Ring B represents a heteroaromatic ring having two or more nitrogens, Ar １ and Ar ２ each independently represent an aromatic ring or a heteroaromatic ring, α and β each independently represent a substituted or unsubstituted phenyl group, Ht ｕｎｉ represents a skeleton having hole transporting properties, and n and m each independently represent an integer from 0 to 4.)

3. It has an anode, a cathode, and a light-emitting layer, The light-emitting layer is located between the anode and the cathode. The light-emitting layer comprises a light-emitting material and a first organic compound, The aforementioned luminescent material is an organometallic complex represented by general formula (G1), The first organic compound is an organic compound represented by general formula (G10), and the device is a light-emitting device. 【Chemistry 2】 (However, in general formula (G1), M represents the central metal, the dashed line represents coordination, and ring A １ and ring A ２ Each of these independently represents an aromatic ring or a heteroaromatic ring, R １ ~R ４ At least one of them is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent one of the following: hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and an aryl group having 6 to 13 carbon atoms forming a substituted or unsubstituted ring, R ５ ~R ８ Each of the following independently represents hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, and an aryl group having 6 to 13 carbon atoms forming a substituted or unsubstituted ring, and k represents an integer from 0 to 2. In general formula (G10), ring B represents a heteroaromatic ring having 2 or more nitrogen atoms, and Ar １ and Ar ２ Each of the following independently represents an aromatic ring or a heteroaromatic ring, and α and β independently represent a substituted or unsubstituted phenyl group, and Ht ｕｎｉ (where represents a hole-transporting skeleton, and n and m each independently represent integers from 0 to 4.)

4. It has an anode, a cathode, and a light-emitting layer, The light-emitting layer is located between the anode and the cathode. The light-emitting layer comprises a light-emitting material and a first organic compound, The aforementioned luminescent material is an organometallic complex represented by the general formula (G2), The first organic compound is an organic compound represented by general formula (G10), and the device is a light-emitting device. 【Transformation 3】 (However, in general formula (G2), M represents the central metal, the dashed line represents coordination, Q represents oxygen or sulfur, and X １ ~X ８ Each of these independently represents either nitrogen or carbon (including CH), and R １ ~R ４ At least one of them is a deuterium-substituted alkyl group having 1 to 6 carbon atoms, and the others each independently represent hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 13 carbon atoms forming a substituted or unsubstituted ring, R ５ ~R １４ Each of the following independently represents hydrogen (including deuterium), an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 13 carbon atoms forming a substituted or unsubstituted ring, and k represents an integer from 0 to 2. In general formula (G10), ring B represents a heteroaromatic ring having 2 or more nitrogen atoms, and Ar １ and Ar ２ Each of the following independently represents an aromatic ring or a heteroaromatic ring, and α and β independently represent a substituted or unsubstituted phenyl group, and Ht ｕｎｉ (where represents a hole-transporting skeleton, and n and m each independently represent integers from 0 to 4.)

5. In any one of claims 1 to 4, A light-emitting device wherein the lowest triplet excitation energy of the first organic compound is greater than the lowest triplet excitation energy of the organometallic complex.

6. In claim 5, A light-emitting device in which the difference between the lowest triplet excitation energy of the first organic compound and the lowest triplet excitation energy of the organometallic complex is greater than 0 eV and 0.40 eV or less.

7. In any one of claims 1 to 4, The aforementioned central metal is iridium, in this light-emitting device.

8. In any one of claims 1 to 4, A light-emitting device wherein the heteroaromatic ring having two or more nitrogen atoms is any of the structural formulas (B-1) to (B-32). 【Chemistry 4】

9. In any one of Claims 1 to 4, The aforementioned hole-transporting skeleton is a π-electron-rich heteroaromatic ring, which is used in this light-emitting device.

10. A light-emitting device comprising a light-emitting device according to any one of claims 1 to 4, and a transistor or a substrate.

11. An electronic device having a light-emitting device according to claim 10, and a detection unit, an input unit, or a communication unit.

12. A lighting device comprising a light-emitting device according to claim 10 and a housing.

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