Light emitting device

Abstract

Provided is a light-emitting device having good reliability. The light emitting device includes a first electrode formed on an insulating surface, a second electrode opposed to the first electrode, and an EL layer between the first electrode and the second electrode, one of the first electrode and the second electrode being an anode and the other being a cathode, the EL layer including a light emitting layer, a first layer, and a second layer, the first layer and the second layer are located between the light-emitting layer and the cathode, the first layer is located between the first electrode and the second layer, and the second layer is located between the first layer and the second electrode. GSPSlope (mV / nm) of the second layer is larger than GSPSlope (mV / nm) of the first layer (notably, GSPSlope (mV / nm) represents [Delta] V / [Delta] d, and [Delta] V (mV) is the amount of change in surface potential with respect to the amount of change in thickness [Delta] d (nm)).

Description

Technical Field

[0001] One aspect of this invention relates to an organic compound, an organic semiconductor element, a light-emitting element, an organic EL element, a photodiode, a display module, a lighting module, a display device, a light-emitting device, an electronic device, a lighting device, and an electronic device. Note that this aspect of the invention is not limited to the aforementioned technical fields. The technical field of one aspect of the invention disclosed in this specification relates to an object, method, or manufacturing method. Furthermore, one aspect of the invention relates to a process, machine, manufacture, or composition of matter. Therefore, more specifically, examples of the technical field of one aspect of the invention disclosed in this specification include semiconductor devices, display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, imaging devices, and methods for driving or manufacturing these devices. Background Technology

[0002] The practical application of light-emitting devices (organic EL elements) utilizing electroluminescence (EL) with organic compounds is very active. In the basic structure of these organic EL elements, an organic compound layer (EL layer) containing a luminescent material is sandwiched between a pair of electrodes. By applying a voltage to the device and injecting charge carriers, light emission from the luminescent material can be obtained using the recombination energy of these charge carriers.

[0003] Because this type of organic EL element is a self-emissive EL element, it offers advantages over liquid crystal displays (LCDs) in terms of higher visibility and the elimination of the need for a backlight when used in display pixels. Furthermore, displays using this type of EL element can be manufactured to be thin and lightweight, which is a significant advantage. Moreover, its extremely fast response time is also a characteristic of this organic EL element.

[0004] Furthermore, because the light-emitting layer of this organic EL element can be formed continuously in a planar shape, surface emission can be achieved. Since this characteristic is difficult to obtain in point light sources such as incandescent lamps and LEDs, or line light sources such as fluorescent lamps, the aforementioned light-emitting device is highly valuable as a surface light source for illumination and other applications.

[0005] As mentioned above, displays or lighting devices using organic EL elements can be adapted for a wide variety of electronic devices, and research and development of organic EL elements with better characteristics are becoming increasingly active.

[0006] [Non-Patent Literature 1] Hiroshi Noguchi and 2 others, "Orientational Polarization Phenomenon of Polar Molecules and Interfacial Characteristics of Organic Thin Film Devices," Journal of the Vacuum Society of Japan, 2015, Vol. 58, No. 3 Summary of the Invention

[0007] One objective of this invention is to provide a light-emitting device with high reliability. Another objective of this invention is to provide a light-emitting device with high luminous efficiency. One objective of this invention is to provide a light-emitting device with low driving voltage. Furthermore, one objective of this invention is to provide any one of a light-emitting device, an electronic device, and a display device with high reliability.

[0008] Furthermore, one objective of this invention is to provide a blue phosphorescent light-emitting device with high reliability. Another objective of this invention is to provide a light-emitting device with high luminous efficiency. A further objective of this invention is to provide a blue phosphorescent light-emitting device with low driving voltage.

[0009] Note that the description of these objectives does not preclude the existence of other objectives. Note that one embodiment of the invention does not necessarily require achieving all of the above objectives. Note that objectives other than those described above can be understood and extracted from the description, drawings, claims, etc.

[0010] One aspect of the present invention is a light-emitting device, comprising: a first electrode formed on an insulating surface; a second electrode opposite to the first electrode; and an EL layer located between the first electrode and the second electrode. The EL layer includes a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer. The first electron transport layer is located between the first electrode and the second electron transport layer, and the light-emitting layer is located between the hole transport layer and the first and second electron transport layers. The GSP_Slope (mV / nm) of the second electron transport layer is greater than that of the first electron transport layer (mV / nm).

[0011] Another aspect of the present invention is a light-emitting device, comprising: a first electrode formed on an insulating surface; a second electrode opposite to the first electrode; and an EL layer located between the first electrode and the second electrode. The EL layer includes a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer. The first electron transport layer is located between the first electrode and the second electron transport layer. The light-emitting layer is located between the hole transport layer and the first and second electron transport layers. The first electron transport layer includes a first organic compound, and the second electron transport layer includes a second organic compound. The first and second organic compounds have π-electron-deficient heteroaromatic rings. The GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

[0012] Another aspect of the present invention is a light-emitting device, comprising: a first electrode formed on an insulating surface; a second electrode opposite to the first electrode; and an EL layer located between the first electrode and the second electrode. The EL layer includes a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer. The first electron transport layer is located between the light-emitting layer and the second electron transport layer, and the second electron transport layer is located between the first electron transport layer and the second electrode. The light-emitting layer is located between the hole transport layer and the first electron transport layer. The first electron transport layer includes a first organic compound, and the second electron transport layer includes a second organic compound and a first substance. The first organic compound and the second organic compound have π-electron-deficient heteroaromatic rings. The GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

[0013] Another aspect of the present invention is a light-emitting device, comprising: a first electrode formed on an insulating surface; a second electrode opposite to the first electrode; and an EL layer located between the first electrode and the second electrode. The EL layer includes a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer. The first electron transport layer is located between the light-emitting layer and the second electron transport layer, and the second electron transport layer is located between the first electron transport layer and the second electrode. The light-emitting layer is located between the hole transport layer and the first electron transport layer. The first electron transport layer includes a first organic compound, and the second electron transport layer includes a second organic compound and a first substance. The first organic compound and the second organic compound have π-electron-deficient heteroaromatic rings. When the mixing ratio of the second organic compound and the first substance in the second electron transport layer is x:y, the GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than (x+y) / x times the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

[0014] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein y is greater than or equal to x.

[0015] Another aspect of the present invention is a light-emitting device having the above-described structure, wherein the light-emitting layer comprises a phosphorescent material.

[0016] Another aspect of the present invention is a light-emitting device having the above-described structure, wherein a phosphorescent material emits light when a voltage is applied between the first electrode and the second electrode.

[0017] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the second electron transport layer is located between the first electron transport layer and the second electrode, and the GSP_Slope (mV / nm) of the light-emitting layer is greater than the GSP_Slope (mV / nm) of the first electron transport layer.

[0018] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the GSP_Slope (mV / nm) of the light-emitting layer is greater than the GSP_Slope (mV / nm) of the hole transport layer.

[0019] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the second electron transport layer is located between the first electron transport layer and the second electrode, the light-emitting layer comprises a host material and a light-emitting substance, and the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

[0020] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the host material.

[0021] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the hole transport layer comprises a third organic compound, and the GSP_Slope (mV / nm) of the light-emitting layer is greater than or equal to the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound.

[0022] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the hole transport layer comprises a third organic compound, and the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is greater than or equal to the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound.

[0023] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the host material comprises a first material and a second material, and the first material and the second material are organic compounds that form a combination of excitocomplexes.

[0024] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the first material is an organic compound having a π-electron-deficient heteroaromatic ring, and the second material is an organic compound having a π-electron-rich heteroaromatic ring or an aromatic amine.

[0025] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the first substance is a metal complex.

[0026] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the metal complex is an organic complex containing an alkali metal.

[0027] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the emission spectrum of the phosphorescent material has a peak wavelength of 450 nm or more and 520 nm or less.

[0028] In addition, another aspect of the present invention is a light-emitting device having the above-described structure, wherein the peak wavelength of the emission spectrum of the light-emitting material is above 450 nm and below 520 nm.

[0029] Note that in one embodiment of the invention, GSP_Slope (mV / nm) is expressed as ΔV / Δd, where ΔV (mV) is the change in surface potential with respect to a change in thickness Δd (nm).

[0030] One aspect of the present invention can provide a highly reliable light-emitting device. Furthermore, another aspect of the present invention can provide a light-emitting device with high luminous efficiency. One aspect of the present invention can provide a light-emitting device with low driving voltage. Additionally, one aspect of the present invention can provide any one of a reliable light-emitting device, electronic device, and display device.

[0031] Furthermore, one aspect of the present invention can provide a blue phosphorescent light-emitting device with high reliability. Another aspect of the present invention can provide a blue phosphorescent light-emitting device with high luminous efficiency. One aspect of the present invention can provide a blue phosphorescent light-emitting device with low driving voltage.

[0032] Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the invention does not necessarily require all of the above-described effects. Note that effects other than those described above can be understood and extracted from the description, drawings, claims, etc. Attached Figure Description

[0033] Figure 1A and Figure 1B This is a diagram illustrating the structure of the light-emitting device according to the embodiment;

[0034] Figure 2A and Figure 2B This is a diagram illustrating the structure of the light-emitting device according to the embodiment;

[0035] Figure 3 This is a graph showing the capacitance-voltage characteristics of measuring device 1;

[0036] Figure 4 This is a graph showing the current density-voltage characteristics of measuring device 1;

[0037] Figure 5A and Figure 5B This is a diagram illustrating the structure of the light-emitting device according to the embodiment;

[0038] Figure 6A and Figure 6B These are the top view and cross-sectional view of the light-emitting device;

[0039] Figure 7A and Figure 7B This is a perspective view showing an example of the structure of a display module;

[0040] Figure 8A and Figure 8B This is a cross-sectional view showing an example of the structure of a display device;

[0041] Figure 9 This is a perspective view showing an example of the structure of a display device;

[0042] Figure 10 This is a cross-sectional view showing an example of the structure of a display device;

[0043] Figure 11 This is a cross-sectional view showing an example of the structure of a display device;

[0044] Figure 12 This is a cross-sectional view showing an example of the structure of a display device;

[0045] Figures 13A to 13D This is a diagram illustrating an example of an electronic device;

[0046] Figures 14A to 14F This is a diagram illustrating an example of an electronic device;

[0047] Figures 15A to 15G This is a diagram illustrating an example of an electronic device;

[0048] Figure 16 It is a diagram showing the brightness-current density characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0049] Figure 17 This is a diagram showing the brightness-voltage characteristics of light-emitting devices 1-1, 1-2, and 1-3;

[0050] Figure 18 It is a graph showing the current efficiency-current density characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0051] Figure 19 It is a graph showing the current density-voltage characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0052] Figure 20 This is a graph showing the blue indicator-current density characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0053] Figure 21 This is a diagram showing the external quantum efficiency-current density characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0054] Figure 22 This is a diagram showing the electroluminescence spectra of light-emitting devices 1-1, 1-2, and 1-3;

[0055] Figure 23 This is a diagram showing the chromaticity diagrams of light-emitting devices 1-1, 1-2, and 1-3;

[0056] Figure 24 It is a graph showing the normalized brightness time variation characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0057] Figure 25 It is a graph showing the voltage-time characteristics of light-emitting devices 1-1, 1-2 and 1-3;

[0058] Figure 26 It is a graph showing the luminance-current density characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0059] Figure 27 It is a diagram showing the brightness-voltage characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0060] Figure 28It is a graph showing the current efficiency-current density characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0061] Figure 29 It is a graph showing the current density-voltage characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0062] Figure 30 This is a graph showing the blue index-current density characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0063] Figure 31 It is a diagram showing the external quantum efficiency-current density characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0064] Figure 32 It is a graph showing the electroluminescence spectra of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0065] Figure 33 It is a graph showing the normalized brightness time variation characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, comparison light-emitting device 2-1, comparison light-emitting device 2-2a, and comparison light-emitting device 2-2b;

[0066] Figure 34A and Figure 34B This is a diagram showing the light-emitting device 2 and comparing the capacitance-voltage characteristics of the light-emitting device 2;

[0067] Figure 35 This is a graph showing the light-emitting device 3 and comparing the brightness-current density characteristics of the light-emitting device 3;

[0068] Figure 36 This is a graph showing the light-emitting device 3 and comparing the current efficiency-current density characteristics of the light-emitting device 3;

[0069] Figure 37 This is a diagram showing the light-emitting device 3 and comparing the brightness-voltage characteristics of the light-emitting device 3;

[0070] Figure 38 This is a graph showing the light-emitting device 3 and comparing the current density-voltage characteristics of the light-emitting device 3;

[0071] Figure 39 This is a graph showing the light-emitting device 3 and the blue indicator-current density characteristics of the comparative light-emitting device 3;

[0072] Figure 40 This is a diagram showing the light-emitting device 3 and comparing the external quantum efficiency-current density characteristics of the light-emitting device 3;

[0073] Figure 41 This is a diagram showing the electroluminescence spectrum of light-emitting device 3 and a comparison of light-emitting device 3;

[0074] Figure 42 This is a diagram showing the chromaticity diagram of the light-emitting device 3 and a comparison diagram of the light-emitting device 3;

[0075] Figure 43 This is a graph showing the light-emitting device 3 and comparing the normalized brightness time variation characteristics of the light-emitting device 3;

[0076] Figure 44 This is a graph showing the emission spectra of single films of SiTrzCz2 and PSiCzCz and the PL spectrum of a mixed film with a weight ratio of SiTrzCz2:PSiCzCz=1:1. Detailed Implementation

[0077] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the contents described below, and its methods and details can be varied in various forms without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the contents described in the embodiments shown below.

[0078] Furthermore, for ease of understanding, the positions, sizes, and extents of various structures shown in the accompanying drawings, etc., do not necessarily represent their actual positions, sizes, and extents. Therefore, the disclosed invention is not necessarily limited to the positions, sizes, and extents disclosed in the accompanying drawings, etc.

[0079] In this specification, ordinal numbers such as "first" and "second" are used for convenience, but they do not limit the number of constituent elements or their order. The order of constituent elements may include, for example, a process sequence or a stacking sequence. That is, the ordinal numbers used in the embodiments of this specification may differ from those used in the claims. Furthermore, the ordinal numbers used in the embodiments of this specification may differ from those used in the claims.

[0080] Furthermore, in this specification and the like, when the structure of the invention is described using the accompanying drawings, the same symbol is sometimes used in different drawings to show the same parts.

[0081] Furthermore, in this specification and other materials, the terms "film" and "layer" may be interchanged. For example, "conductive layer" may sometimes be replaced with "conductive film." Or, for example, "insulating film" may sometimes be replaced with "insulating layer."

[0082] Note that in this specification, photoluminescence (PL) spectroscopy refers to the spectrum obtained by fixing the excitation wavelength of the excitation light in fluorescence spectrophotometry and separating the light emitted by the sample irradiated by the excitation light according to each wavelength to measure the distribution of the luminescence intensity at each wavelength. It is sometimes also called emission spectrum. Note that emission spectrum sometimes includes fluorescent and phosphorescent components. In this specification, emission spectra consisting of fluorescent components are sometimes specifically referred to as fluorescence spectra, and emission spectra consisting of phosphorescent components are particularly referred to as phosphorescent spectra.

[0083] Implementation Method 1

[0084] In this embodiment, refer to Figure 1A and Figure 1B The present invention describes a light-emitting device 10A of one embodiment of the present invention and a light-emitting device 10B of another embodiment of the present invention.

[0085] like Figure 1A and Figure 1B As shown, both light-emitting devices 10A and 10B are located on the substrate 1000. Both light-emitting devices 10A and 10B include a first electrode 101, a second electrode 102, and an EL layer 103 located between the first electrode 101 and the second electrode 102. Furthermore, as... Figure 1A and Figure 1B As shown, the EL layer 103 includes at least a light-emitting layer 113, a first electron transport layer 114_1, and a second electron transport layer 114_2. The first electron transport layer 114_1 and the second electron transport layer 114_2 have the function of transporting electrons injected into the EL layer 103 from one of the first electrode 101 and the second electrode 102 to the light-emitting layer 113. Note that the first electron transport layer 114_1 is located between the first electrode 101 and the second electron transport layer 114_2.

[0086] In addition, such as Figure 1A and Figure 1BAs shown, in light-emitting devices 10A and 10B, a first electrode 101 is formed on a substrate 1000. The first electrode 101 can be disposed between the second electrode 102 and the substrate 1000. That is, the first electrode 101 is the electrode disposed before the second electrode 102. When a transistor is disposed on the substrate 1000, the first electrode 101 is electrically connected to the transistor via wiring. Alternatively, the first electrode 101 is disposed on an insulating layer on which an external connection electrode is disposed, which is used as a terminal for disposing of an FPC (Flexible Printed Circuit), etc. Alternatively, the end of the first electrode 101 is covered by an insulating film.

[0087] Figure 1A The light-emitting device 10A shown is Figure 1B The difference in the light-emitting device 10B shown lies in the different functions of the first electrode 101 and the second electrode 102. In the light-emitting device 10A, the first electrode 101 is used as the anode, and the second electrode 102 is used as the cathode. In this specification, etc., a light-emitting device, like the light-emitting device 10A, in which the first electrode disposed on one side of the substrate is used as the anode, is sometimes referred to as a positively oriented light-emitting device. On the other hand, in the light-emitting device 10B, the first electrode 101 is used as the cathode, and the second electrode 102 is used as the anode. In this specification, etc., a light-emitting device, like the light-emitting device 10B, in which the first electrode disposed on one side of the substrate is used as the cathode, is sometimes referred to as an inverted light-emitting device.

[0088] Holes injected from the first electrode 101 of the anode into the EL layer 103 and transported by the hole transport layer 112, and electrons injected from the second electrode 102 of the cathode into the EL layer 103 and transported by the electron transport layer 114, recombine in the light-emitting layer 113, thereby causing the upright light-emitting device 10A to emit light. Therefore, in the light-emitting device 10A, the hole transport layer 112 is located between the first electrode 101 and the light-emitting layer 113, and the electron transport layer 114 is located between the second electrode 102 and the light-emitting layer 113.

[0089] Electrons injected into the EL layer 103 from the first electrode 101 (serving as the cathode) and transported by the electron transport layer 114, and holes injected into the EL layer 103 from the second electrode 102 (serving as the anode) and transported by the hole transport layer 112, recombine in the light-emitting layer 113, thereby causing the inverted light-emitting device 10B to emit light. Therefore, in the light-emitting device 10B, the hole transport layer 112 is located between the second electrode 102 and the light-emitting layer 113, and the electron transport layer 114 is located between the first electrode 101 and the light-emitting layer 113.

[0090] In light-emitting devices 10A and 10B, the electron transport layer has a stacked structure (a stack of the first electron transport layer 114_1 and the second electron transport layer 114_2). Furthermore, the hole transport layer 112 can be a single-layer structure or a stacked structure. Note that sometimes the first electron transport layer 114_1 and the second electron transport layer 114_2 are collectively referred to as electron transport layer 114.

[0091] Furthermore, light-emitting devices 10A and 10B preferably include a hole transport layer 112 between the anode and the light-emitting layer 113, and more preferably include a hole injection layer 111 between the anode and the hole transport layer 112. Furthermore, light-emitting devices 10A and 10B more preferably include an electron injection layer 115 between the cathode and the electron transport layer 114.

[0092] Figure 1A The upright light-emitting device 10A shown 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, an electron injection layer 115, and a second electrode 102 serving as a cathode are sequentially stacked on a first electrode 101 serving as an anode. Furthermore, Figure 1B The inverted light-emitting device 10B shown has a structure in which an electron injection layer 115, an electron transport layer 114, a light-emitting layer 113, a hole transport layer 112, a hole injection layer 111, and a second electrode 102 serving as an anode are sequentially stacked on a first electrode 101 serving as a cathode.

[0093] Note that the structures of light-emitting devices 10A and 10B are not limited to... Figure 1A and Figure 1B The structure shown is an example. For instance, a structure with two hole transport layers, or a structure with one or both of the hole transport layer and electron transport layer having three or more layers, can also be used.

[0094] In the light-emitting devices 10A and 10B with a stacked electron transport layer, the inventors have discovered that by selecting materials for each layer taking into account the tilt of the giant surface potential (GSP) of the electron transport layer, the reliability of the light-emitting devices 10A and 10B can be improved.

[0095] In other words, when the electron transport layer has a stacked structure of a first electron transport layer 114_1 formed first and a second electron transport layer 114_2 formed later, the light-emitting device with a GSP slope (GSP_Slope (mV / nm)) of the second electron transport layer 114_2 being greater than that of the first electron transport layer 114_1 can be a light-emitting device with good reliability.

[0096] Alternatively, when the electron transport layer has a stacked structure of a first electron transport layer 114_1 formed first and a second electron transport layer 114_2 formed subsequently, the light-emitting device with a GSP slope (GSP_Slope (mV / nm)) greater than that of the film containing the organic compound with the π-electron-deficient heteroaromatic ring in the second electron transport layer 114_2 is a light-emitting device with good reliability.

[0097] Here, GSP is a phenomenon caused by spontaneous polarization (SOP) resulting from the orientation of the permanent electric dipole moment of the vapor-deposited film concentrated in the thickness direction.

[0098] The surface potential of vapor-deposited films exhibiting GSP changes proportionally and in an unsaturated manner with increasing thickness. For example, the surface potential of a vapor-deposited film of tris(8-hydroxyquinoline) aluminum (Alq3) reaches approximately 28V at a thickness of 560nm. Its electric field strength reaches 5×10⁻⁶. 5 V / cm, which is roughly equivalent to the electric field strength when driving a typical light-emitting device.

[0099] The slope of a gas-phase (GSP) is expressed as ΔV / Δd, where ΔV (mV) is the change in surface potential in a film where the GSP varies proportionally to the thickness, with respect to a change in thickness Δd (nm). Furthermore, a positive GSP slope occurs when the surface potential increases with increasing thickness, and a negative GSP slope occurs when the surface potential decreases with increasing thickness. Alq3 described above can be considered a material with a positive GSP slope. Additionally, in layers with a positive GSP slope, the potential on the substrate side is low, and in layers with a negative GSP slope, the potential on the substrate side is high.

[0100] As described above, the GSP (Gravity Spread) is a phenomenon caused by the SOP (Slope of Orientation) resulting from the concentration of the permanent electric dipole moment along the thickness direction. That is, in a layer with a positive GSP_Slope, it can be considered that a negative polarization charge is generated on the substrate side of the layer, and a positive polarization charge is generated on the second electrode side. Similarly, in a layer with a negative GSP_Slope, it can be considered that a positive polarization charge is generated on the substrate side of the layer, and a negative polarization charge is generated on the second electrode side. This polarization charge induction is the source of the GSP. Note that in... Figure 1A and Figure 1B In the middle, with σ + and σ -This represents the spontaneous polarization (SOP) resulting from the concentration of the permanent electric dipole moments of each layer deposited by vapor deposition along the thickness direction. σ+ represents positive polarization, and σ- represents negative polarization. Furthermore, the more σ values ​​near the interfaces of each layer, the greater the spontaneous polarization.

[0101] Most vapor-deposited films of organic compounds have a positive GSP_Slope. In this case, when a second layer is deposited in contact with the first layer, the GSP_Slope of both the first and second layers becomes positive. This can be considered as the generation of negative polarization charge on the substrate side of each layer and positive polarization charge on the second electrode side. At this time, the negative polarization charge on the first layer side of the second layer cancels out the positive polarization charge on the second layer side of the first layer. Therefore, only the remaining charge can be regarded as the interface charge (fixed charge) at the interface between the first and second layers. Note that in this specification, the virtual charge that can be regarded as the interface charge is sometimes referred to as the interface charge.

[0102] Figure 1A This shows a positively positioned light-emitting device 10A. Figure 1B An inverted light-emitting device 10B is shown. The electron transport layer 114 has a stacked structure of a first electron transport layer 114_1 and a second electron transport layer 114_2. Note that the second electron transport layer 114_2 is closer to the second electrode 102 than the first electron transport layer 114_1. In one embodiment of the light-emitting device of the present invention, the GSP_Slope of the second electron transport layer 114_2 is preferably larger than the GSP_Slope of the first electron transport layer 114_1. Alternatively, in one embodiment of the light-emitting device of the present invention, the GSP_Slope of the vapor-deposited film of the second organic compound having a π-electron-deficient heteroaromatic ring contained in the second electron transport layer 114_2 is preferably larger than the GSP_Slope of the vapor-deposited film of the first organic compound having a π-electron-deficient heteroaromatic ring contained in the first electron transport layer 114_1.

[0103] In one embodiment of the light-emitting device of the present invention having this structure, a negative interface charge is generated at the interface between the second electron transport layer 114_2 and the first electron transport layer 114_1, thus the injection of electrons from the second electrode 102 or the electron injection layer 115 into the second electron transport layer 114_2 ( Figure 1A When upright) or the injection of electrons from the first electrode 101 or the electron injection layer 115 to the first electron transport layer 114_1 (when upright) Figure 1B When inverted, this is suppressed. Therefore, it prevents the light-emitting layer 113 from becoming over-electron, reduces the bias of the light-emitting layer 113 in the recombination region towards the hole transport layer 112, and thus reduces the degradation of the light-emitting layer 113 and the hole transport layer 112 (or electron blocking layer). Therefore, one embodiment of the light-emitting device of the present invention can be a highly reliable light-emitting device.

[0104] Note that the luminescent layer 113 contains at least a luminescent material, and preferably also a host material. As the luminescent material is a blue luminescent material with a high excitation energy level, the band gap of the host material increases, making it difficult to control carrier balance. In particular, most blue phosphorescent light-emitting devices containing blue phosphorescent materials have a structure where the luminescent layer 113 tends to have an excess of electrons. Therefore, this invention is suitable for phosphorescent light-emitting devices, especially blue phosphorescent light-emitting devices, and significantly improves reliability.

[0105] In addition, Figure 1A In the positive-position light-emitting device 10A, the second electron transport layer 114_2 may contain a first substance in addition to the second organic compound. The first substance is preferably an organic complex containing a metal complex, particularly an organic complex containing an alkali metal. Specifically, 8-hydroxyquinoline-lithium (Liq), 8-hydroxyquinoline-sodium (Naq), 8-hydroxyquinoline-potassium (Kq), and their derivatives can be used as organic complexes containing alkali metals. When the second electron transport layer 114_2 contains such a substance, the electron transport properties in the second electron transport layer 114_2 can be controlled. Furthermore, by suppressing the light-emitting layer 113 in the recombination region from being biased towards the hole transport layer 112, the reliability of the light-emitting device can be improved.

[0106] Note that, at this point, when the mixing ratio (weight ratio) of the second organic compound and the first substance in the second electron transport layer 114_2 is x:y, the GSP_Slope (mV / nm) of the second organic compound film is preferably greater than (x+y) / x times the GSP_Slope (mV / nm) of the first organic compound film. By employing this structure, even when the GSP_Slope of the first substance film is smaller than the GSP_Slope of the second organic compound film, the GSP_Slope (mV / nm) of the second electron transport layer 114_2 is greater than that of the first electron transport layer 114_1, thereby generating a negative interface charge and suppressing electron injection, which is therefore preferred. Furthermore, when y is greater than x, the ratio of the second organic compound performing electron transport decreases, and electron transport performance declines, which is also preferred.

[0107] In addition, Figure 1B In the inverted light-emitting device 10B, the first electron transport layer 114_1 may contain a first substance in addition to the first organic compound. The first substance is preferably a metal complex, particularly an organic complex containing an alkali metal. When the first electron transport layer 114_1 contains such a substance, the electron transport properties in the first electron transport layer 114_1 can be controlled. Furthermore, by suppressing the light-emitting layer 113 in the recombination region from being biased towards the hole transport layer 112, the reliability of the light-emitting device can be improved.

[0108] In addition, such as Figure 2A As shown, when a positive-type light-emitting device according to one embodiment of the present invention includes a hole transport layer 112 in contact with the light-emitting layer 113, the GSP_Slope (mV / nm) of the light-emitting layer 113 is preferably greater than the GSP_Slope (mV / nm) of the hole transport layer or the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound containing a π-electron-rich heteroaromatic ring or aromatic amine included in the hole transport layer 112. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is preferably greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound containing a π-electron-rich heteroaromatic ring or aromatic amine included in the hole transport layer 112.

[0109] In addition, such as Figure 2B As shown, when an inverted light-emitting device according to one embodiment of the present invention includes a hole transport layer 112 in contact with the light-emitting layer 113, the GSP_Slope (mV / nm) of the light-emitting layer 113 is preferably smaller than the GSP_Slope (mV / nm) of the hole transport layer or the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound containing a π-electron-rich heteroaromatic ring or aromatic amine included in the hole transport layer 112. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is preferably smaller than the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound containing a π-electron-rich heteroaromatic ring or aromatic amine included in the hole transport layer 112.

[0110] In one embodiment of the present invention, a light-emitting device having this structure promotes hole injection from hole injection layer 111 to hole transport layer 112 through the effect of negative interface charge derived from the difference in GSP slope between two layers in contact with each other. As a result, hole injection into the light-emitting layer is also effectively generated, and carrier balance is improved. This further expands the recombination region and suppresses the degradation of the light-emitting layer 113 and the hole transport layer 112.

[0111] In addition, such as Figure 1A As shown, in one embodiment of the positive-type light-emitting device of the present invention, the GSP_Slope (mV / nm) of the light-emitting layer 113 is preferably greater than the GSP_Slope (mV / nm) of the first electron transport layer 114_1. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is preferably greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

[0112] In addition, such as Figure 1BAs shown, in an inverted light-emitting device according to one embodiment of the present invention, the GSP_Slope (mV / nm) of the light-emitting layer 113 is preferably smaller than the GSP_Slope (mV / nm) of the second electron transport layer 114_2. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is preferably smaller than the GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound.

[0113] In one embodiment of the present invention, the light-emitting device exhibiting this structure promotes electron injection from the second electron transport layer 114_2 to the first electron transport layer 114_1 due to the positive interface charge arising from the difference in GSP slope between the two contacting layers. Therefore, even if electron injection from the first electrode 101 or electron injection layer 115 to the second electron transport layer 114_2 is suppressed in one embodiment of the present invention, a significant increase in the driving voltage is not caused, thus enabling the realization of a light-emitting device with excellent characteristics.

[0114] In addition, such as Figure 1A As shown, in one embodiment of the positive-type light-emitting device of the present invention, the GSP_Slope (mV / nm) of the second electron transport layer 114_2 is preferably greater than the GSP_Slope (mV / nm) of the light-emitting layer 113. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is preferably greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the host material.

[0115] In addition, such as Figure 1B As shown, in an inverted light-emitting device according to one embodiment of the present invention, the GSP_Slope (mV / nm) of the first electron transport layer 114_1 is preferably smaller than the GSP_Slope (mV / nm) of the light-emitting layer 113. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound is preferably smaller than the GSP_Slope (mV / nm) of the vapor-deposited film of the host material.

[0116] In one embodiment of the present invention, the interface charge between the first electron transport layer 114_1 and the second electron transport layer 114_2 of the light-emitting device having this structure is negative, and this interface charge is less than the interface charge between the light-emitting layer 113 and the first electron transport layer 114_1. Through this effect, although electron injection into the light-emitting layer is suppressed, hole injection into the light-emitting layer is promoted, thus improving carrier balance and further expanding the recombination region while suppressing the degradation of the light-emitting layer 113 and the hole transport layer 112.

[0117] Note that when the light-emitting layer 113 comprises a host material, the host material preferably comprises a first material and a second material. By constituting the host material from multiple materials, it is easier to further control the carrier balance, thus contributing to improved reliability. Alternatively, by using the first material and the second material to form an excimer complex, effects such as improved energy transfer efficiency to the light-emitting material, lower driving voltage, and improved reliability are achieved. Preferably, one of the first material and the second material is an organic compound with a π-electron-deficient heteroaromatic ring, and the other is an organic compound with a π-electron-rich heteroaromatic ring or an aromatic amine, thereby making it easier to adjust the carrier balance.

[0118] When the host material comprises multiple materials, the GSP_Slope (mV / nm) of the film serving as the host material can be the GSP_Slope (mV / nm) of a mixed film of the first and second materials co-deposited in a 1:1 ratio. Alternatively, the GSP_Slope (mV / nm) of the vapor-deposited film of the material with a higher mixing ratio in the first and second materials can be regarded as the GSP_Slope (mV / nm) of the host material film.

[0119] <Methods for determining GSP_Slope>

[0120] Here, we describe a method for determining the GSP_Slope of an organic compound film formed by vacuum evaporation.

[0121] As mentioned above, the phenomenon that the surface potential of a vapor-deposited film increases proportionally with its thickness is called the giant surface potential (GSP). Generally, the magnitude of the GSP is represented by the slope of the surface potential of the vapor-deposited film, measured using a Kelvin probe, plotted along the thickness direction; this slope is denoted as GSP_Slope (mV / nm). However, when two different layers are stacked, the charge density accumulated at their interface (mC / m) can be used as the indicator. 2 The GSP_Slope is estimated by varying in relation to the GSP.

[0122] Non-Patent Document 1 shows that when an organic thin film (thin film 1 and thin film 2) with different spontaneous polarizations is stacked and a voltage is applied, the following formula holds when the charge carriers accumulated at the interface are holes.

[0123] [Equation 1]

[0124]

[0125] [Equation 2]

[0126]

[0127] In formula (1), σacc σ represents the accumulated charge density. int V represents the interface charge density. inj Represents the hole injection voltage, V th d2 represents the threshold voltage, d2 represents the thickness of film 2, and ε2 represents the dielectric constant of film 2. inj V th It can be estimated from the capacitance-voltage characteristics of the device. Furthermore, the dielectric constant can be obtained using the ordinary optical refractive index n. o The square of (wavelength 633nm). Thus, V is estimated from the capacitance-voltage characteristic. inj V th The dielectric constant ε2 of thin film 2, calculated from the refractive index, and the thickness d2 of thin film 2, can be used to calculate the interfacial charge density σ using formula (1). int .

[0128] Next, in equation (2), P n ε represents the spontaneous polarization of the thin film n (n is 1 or 2) along the substrate normal direction. n V represents the dielectric constant of thin film n. n d represents the potential at the membrane surface. n This represents the thickness of the thin film n. Furthermore, the potential (V) at the film surface can be used to determine this. n ) divided by thickness (d) n The value obtained is used to calculate GSP_slope. Here, the interfacial charge density σ can be obtained from the above formula (1). int Therefore, by using the known material as thin film 2 and employing an appropriate dielectric constant, the GSP_slope of thin film 1 can be estimated.

[0129] Thus, the following example is shown: As thin film 2, a measuring device 1 is fabricated using tris(8-hydroxyquinoline)aluminum (abbreviated: Alq3) with a known GSP_Slope of 48 (mV / nm) to calculate the GSP_Slope of the 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated: NPB) membrane.

[0130] Table 1 shows the device structure of the measurement device 1. Note that layer 1_1 of the measurement device 1 is formed from the anode side to the cathode using vacuum evaporation at room temperature and a deposition rate of 0.2 nm / sec to 0.6 nm / sec. Furthermore, deposition continues without stopping while forming a layer. In the measurement device 1, layer 2_1 corresponds to thin film 1 and layer 3_1 corresponds to thin film 2. Additionally, OCHD-003 is an organic compound with electron acceptor properties.

[0131] Note that when manufacturing the measurement device, the deposition rate of each layer is preferably 3 nm / min or more and 600 nm / min or less. Furthermore, the thickness of each layer in the measurement device is preferably 3 nm or more and 500 nm or less, more preferably 50 nm or more and 300 nm or less.

[0132] also, Figure 3 The capacitance-voltage characteristic of measuring device 1 is shown. Note that the capacitance-voltage characteristic was measured using a potentiostat / galvanostat (Biologic SP-300, France) at a frequency of 10 Hz at room temperature.

[0133] [Table 1]

[0134]

[0135] Table 2 shows the utilization Figure 3 The hole injection voltage V of measuring device 1 is obtained by formulas (1) and (2). inj Threshold voltage V th Interfacial charge density σ int SOP, GSP_Slope, and the refractive index n of each material used for calculation. o The refractive index was measured using a spectroscopic ellipsometry (JA Woollam Japan M-2000U).

[0136] [Table 2]

[0137]

[0138] Measurement device 2, which has a structure substantially the same as measurement device 1 except that the thickness of Alq3 is 80 nm, was fabricated. It was confirmed that the hole injection voltage drifted to a lower voltage than that of measurement device 1. In other words, it was found that in the above device, holes are injected first, and charge accumulates at the interface with Alq3. Furthermore, it was confirmed that the same results were obtained when estimating the GSP_Slope using measurement device 2 as with measurement device 1.

[0139] Furthermore, it is difficult to estimate the threshold voltage V from the capacitance-voltage characteristics. th Alternatively, the threshold voltage estimated from the current density-voltage characteristic can be used.

[0140] Figure 4 The current density-voltage characteristics of measuring device 1 are shown.

[0141] V estimated from current density-voltage characteristics th The value is 2.0V, which is the same as the value estimated from the capacitor-voltage characteristic.

[0142] Thus, by fabricating a film with a known Alq3 layered GSP_Slope and using a device with a film formed from an organic compound whose GSP_Slope is to be determined, and measuring the capacitance-voltage characteristics, the GSP_Slope of the organic compound can be estimated.

[0143] The above description explains the method for calculating GSP_Slope when the charge carriers accumulated at the interface become holes. However, when calculating the GSP_Slope of an organic membrane when the charge carriers accumulated at the interface become electrons, it can be calculated in the same way using the following formula (3).

[0144] [Equation 3]

[0145]

[0146] The organic compounds used in the light-emitting device are preferably selected based on the GSP_Slope of the vapor-deposited film of the organic compound, which is pre-measured by the above measurement method.

[0147] Furthermore, the structure shown in this embodiment can be implemented by appropriately combining it with the structures shown in other embodiments.

[0148] Implementation Method 2

[0149] In this embodiment, a semiconductor device according to one aspect of the present invention is described in detail.

[0150] Figures 1A to 2B This is a schematic diagram of a light-emitting device according to one aspect of the present invention. In the light-emitting device, a first electrode 101 is disposed on an insulating substrate 1000, and an EL layer 103 is included between the first electrode 101 and the second electrode 102. The EL layer 103 includes a light-emitting layer 113, which contains a light-emitting material. The light-emitting material emits light by applying a voltage between the first electrode 101 and the second electrode 102.

[0151] In addition to the light-emitting layer 113, the EL layer 103 also includes at least a first electron transport layer 114_1 and a second electron transport layer 114_2, having the structure shown in Embodiment 1. A light-emitting device of one embodiment of the present invention having this structure can be a light-emitting device with good characteristics, especially a light-emitting device with good reliability.

[0152] like Figures 1A to 2B As shown, the EL layer 103 preferably includes other functional layers such as a hole injection layer 111, a hole transport layer 112, and an electron injection layer 115. Note that the EL layer 103 may also include functional layers other than the aforementioned functional layers such as a hole blocking layer, an electron blocking layer, an exciton blocking layer, and a charge generation layer. Conversely, any of the aforementioned layers may not be provided.

[0153] The first electrode 101 and the second electrode 102 are formed in a single-layer or multilayer structure. When the electrode has a multilayer structure, the layer in contact with the EL layer 103 is used as the anode or cathode. When the electrode has a multilayer structure, there are no restrictions on the work function of the layers other than the layer in contact with the EL layer 103, and materials can be selected according to the required characteristics such as resistance, ease of processing, reflectivity, light transmittance, and stability.

[0154] The anode is preferably formed using metals, alloys, conductive compounds, and mixtures thereof with a high work function (specifically 4.0 eV or higher). Examples include indium tin oxide (ITO), indium tin oxide (ITSO) containing silicon or silicon oxide, indium zinc oxide, and indium tin oxide (IWZO) containing tungsten oxide and zinc oxide. While these conductive metal oxide films are typically formed by sputtering, sol-gel methods can also be used. Examples of formation methods include sputtering indium tin oxide using a target containing 1 wt% to 20 wt% zinc oxide. Furthermore, indium tin oxide (IWZO) containing tungsten oxide and zinc oxide can be formed by sputtering using a target containing 0.5 wt% to 5 wt% tungsten oxide and 0.1 wt% to 1 wt% zinc oxide. Furthermore, materials used for the anode include, for example, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti), aluminum (Al), or nitrides of metallic materials (e.g., titanium nitride). The anode can also be a layer of the aforementioned materials stacked together. For example, a film sequentially stacked with Al, Ti, and ITSO on Ti is preferred due to its good reflectivity, resulting in high efficiency and achieving high resolution of several thousand ppi. Graphene can also be used as a material for the anode. Furthermore, by using a composite material that can constitute the hole injection layer 111 described later as the layer in contact with the anode (typically a hole injection layer), the work function can be disregarded when selecting the electrode material.

[0155] Hole injection layer 111 is in contact with the anode and facilitates hole injection into EL layer 103. The hole injection layer 111 can be formed using phthalocyanine compounds and phthalocyanine complexes such as phthalocyanine (H2Pc), copper phthalocyanine (CuPc), etc.; aromatic amine compounds such as 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (DNTPD), etc.; or polymeric compounds such as poly(3,4-ethylenedioxythiophene) / (polystyrene sulfonic acid) (PEDOT / PSS), etc.

[0156] Furthermore, the hole injection layer 111 can also be composed of a substance with electron-accepting properties. As such, organic compounds with electron-withdrawing groups (halogen groups, cyano groups, etc.) can be used, including 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinone dimethylethane (abbreviated: F4-TCNQ), chloroquinone, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviated: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviated: F6-TCNNQ), and 2-(7-dicyanomethylene-1,3,4,5,6,8,9,10-octafluoro-7H-pyrene-2-yl)malononitrile, etc. In particular, compounds such as HAT-CN, which have electron-withdrawing groups bonded to fused aromatic rings with multiple heteroatoms, are thermally stable and therefore preferred. Furthermore, [3] axylene derivatives containing electron-withdrawing groups (especially halogen groups such as fluorine groups, cyano groups, etc.) are preferred due to their very high electron acceptor properties. Specifically, examples include: α,α',α''-1,2,3-cyclopropanetrimethylenetri[4-cyano-2,3,5,6-tetrafluorophenylacetonitrile], α,α',α''-1,2,3-cyclopropanetrimethylenetri[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)phenylacetonitrile], and α,α',α''-1,2,3-cyclopropanetrimethylenetri[2,3,4,5,6-pentafluorophenylacetonitrile]. In addition to the aforementioned organic compounds, transition metal oxides such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide can be used as acceptor substances.

[0157] Furthermore, the hole injection layer 111 is preferably formed of a composite material comprising the aforementioned acceptor material and an organic compound with hole transport properties.

[0158] Various organic compounds with hole-transporting properties can be used as the organic compound for use in composite materials, such as aromatic amines, heteroaromatics, aromatic hydrocarbons, and polymers (oligomers, dendritic polymers, polymers, etc.). Preferably, the organic compound with a hole mobility of 1×10⁻⁶ is used. -6 cm 2 Organic compounds with a ratio of / Vs or higher. The organic compounds with hole-transporting properties used in composite materials are preferably compounds containing fused aromatic rings or π-electron-rich heteroaromatic rings. As fused aromatic rings, anthracene rings, naphthalene rings, etc., are preferred. Furthermore, as π-electron-rich heteroaromatic rings, fused aromatic rings containing at least one of a pyrrole skeleton, a furan skeleton, and a thiophene skeleton are preferred, specifically carbazole rings, dibenzothiophene rings, or rings that are further fused with aromatic rings or heteroaromatic rings.

[0159] Such hole-transporting organic compounds preferably have at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, they can be aromatic amines having substituents including a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines including a naphthyl ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. Note that when these hole-transporting organic compounds are substances including N,N-bis(4-biphenyl)amino groups, long-lifetime light-emitting devices can be manufactured, and therefore they are preferred.

[0160] Specifically, examples of the aforementioned hole-transporting organic compounds include N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated as: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviated as: BBABnf), 4,4'-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4''-phenyltriphenylamine (abbreviated as: BnfBB1BP), and 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-biphenyl Aniline (abbreviated as: ThBA1BP), 4-(2-naphthyl)-4',4''-diphenyltriphenylamine (abbreviated as: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4',4''-diphenyltriphenylamine (abbreviated as: BBAβNBi), 4,4'-diphenyl-4''-([2,1'-binaphthyl]-6-yl)triphenylamine (abbreviated as: BBAαNβNB), 4,4'-diphenyl-4''-([2,1'-binaphthyl]-7-yl)triphenylamine (abbreviated as: BBAαNβNB-03), 4,4'-diphenyl- 4''-(7-phenyl)naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4'-diphenyl-4''-([2,2'-binaphthyl]-6-yl)triphenylamine (abbreviation: BBA(βN2)B), 4,4'-diphenyl-4''-([2,2'-binaphthyl]-7-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4'-diphenyl-4''-([1,2'-binaphthyl]-4-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4'-diphenyl-4''-([1,2'-Binaphthyl]-5-yl)triphenylamine (abbreviation: BBAβNαNB-02), 4-(4-biphenyl)-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenyl)-4'-[4-(2-naphthyl)phenyl]-4''-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenyl)-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'-(carbazole-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4'-[4-(3-phenyl-9H-carbazole-9-yl)phenyl]tri(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4'-(carbazole-9-yl)biphenyl-4-yl]-4'-(2-naphthyl)-4''-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9'-spirodi[9H-fluorene]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9' -spirodi[9H-fluorene]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9'-spirodi[9H-fluorene]-4-amine (abbreviation: BBASF(4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluorene-2-yl)-9,9'-spirodi[9H-fluorene]-4-amine (abbreviation: oFBiSF), N-(biphenyl-4-yl)-N-(9,9-dimethyl-9H-fluorene-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-Phenylo-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: BPAFLP), 4-Phenylo-3'-(9-phenylfluorene-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-Phenylo-4'-[4-(9-phenylfluorene-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), 4-Phenylo-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-Di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviated as: PCCNBB), N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirodi[9H-fluorene]-2-amine (abbreviated as: PCBASF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviated as: PCBBi) F), N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirodi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirodi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirodi-9H-fluoren-2-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9'-spirodi-9H-fluoren-1-amine, etc.

[0161] In addition, as a material with hole transport capabilities, other aromatic amine compounds such as N,N'-bis(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (DTDPPA), 4,4'-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (DPAB), 4,4'-bis(N-{4-[N'-(3-methylphenyl)-N'-phenylamino]phenyl}-N-phenylamino)biphenyl (DNTPD), and 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (DPA3B) can also be used.

[0162] By forming a hole injection layer 111, hole injection capability can be improved, thereby obtaining a light-emitting device with low driving voltage.

[0163] Furthermore, organic compounds with receptor properties can be easily formed in substances with receptor properties using vapor deposition, making them easy-to-use materials.

[0164] The hole transport layer 112 is formed by comprising an organic compound with hole transport properties. Preferably, the organic compound with hole transport properties has a content of 1 × 10⁻⁶. -6 cm 2 Hole mobility above / Vs.

[0165] Examples of materials exhibiting hole transport capabilities include: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (TPD), N,N'-bis(9,9'-spirobis[9H-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (mBPAFLP), and 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (PCBA1BP). Compounds with aromatic amine skeletons include 4,4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCCNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirodi[9H-fluorene]-2-amine (abbreviation: PCBASF);1,3-Bis(N-carbazolyl)benzene (mCP), 4,4'-bis(N-carbazolyl)biphenyl (CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (CzTP), 3,3'-bis(9-phenyl-9H-carbazole) (PCCP), 9,9'-bis(biphenyl-4-yl)-3,3'-bi-9H-carbazole (BisBPCz), 9,9'-bis(biphenyl-3-yl)-3,3'-bi-9H-carbazole (BismBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H- 3,3'-Bicarbazole (abbreviated as mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviated as βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as βNCCBP), 9,9'-bis-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviated as BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-3- 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole 9-(2-naphthyl)-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-phenyl-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviated as: PCCzTp), 9,9'-bis(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenyl-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-[3-(triphenylsilyl)] Compounds with a carbazole skeleton, such as [phenyl]-3,9′-bi-9H-carbazole (abbreviated as: PSiCzCz);Compounds with a thiophene skeleton, such as 4,4',4''-(benzyl-1,3,5-triyl)tris(dibenzothiophene) (abbreviated as DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III), and 4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV); and compounds with a furan skeleton, such as 4,4',4''-(benzyl-1,3,5-triyl)tris(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Compounds with aromatic amine backbones and compounds with carbazole backbones are preferred due to their high reliability and excellent hole transport properties, which help reduce the driving voltage. Note that materials with hole transport properties, such as those used in the hole injection layer 111, can also be appropriately used as materials constituting the hole transport layer 112. Furthermore, organic compounds with amine and fluorene backbones are more preferred. Organic compounds with amine and fluorene backbones have high reliability and high hole transport properties, thus reducing the power consumption of the light-emitting device, and are therefore preferred.

[0166] The luminescent material can be a fluorescent luminescent material, a phosphorescent luminescent material, a material exhibiting thermally activated delayed fluorescence (TADF), or other luminescent materials. Note that in light-emitting devices using blue luminescent materials, especially those using blue phosphorescent materials, the luminescent layer 113 is prone to excessive electrons; therefore, this invention can be applied.

[0167] In the luminescent layer, materials that can be used as fluorescent luminescent substances include, for example, the following substances. Note that other fluorescent luminescent substances can also be used.

[0168] Examples include 5,6-bis[4-(10-phenyl-9-anthrayl)phenyl]-2,2'-bipyridine (abbreviated as PAP2BPy), 5,6-bis[4'-(10-phenyl-9-anthrayl)biphenyl-4-yl]-2,2'-bipyridine (abbreviated as PAPP2BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as 1,6mMemFLPAPrn), and N,N'-bis[4-(9H-9H-fluorene-9-yl)phenyl]pyrene-1,6-diamine (abbreviated as 1,6mMemFLPAPrn). [-carbazole-9-yl)phenyl]-N,N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-carbazole-9-yl)-4'-(10-phenyl-9-anthrayl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-diphenyl-2-anthrayl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole-3-amine (abbreviation: PCAPA), dinaphthalene, 2,5,8,11-tetra-tert-butyl dinaphthalene (abbreviation: TBP), 4-(10-phenyl-9-anthrayl)-4'-(9-phenyl-9H- Carbazole-3-yl)triphenylamine (abbreviated as PCPAPA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis(,N',N'-triphenyl-1,4-phenylenediamine) (abbreviated as DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthrayl)phenyl]-9H-carbazole-3-amine (abbreviated as 2PCAPPA), N-[4-(9,10-diphenyl-2-anthrayl)phenyl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as 2DPAPPA), N,N,N',N',N'',N'',N''',N'''-octaphenyldibenzo[g,p](chrys) N-(9,10-diphenyl-2-anthrayl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as: DBC1), coumarin 30, N-(9,10-diphenyl-2-anthrayl)-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as: 2PCAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthrayl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviated as: 2PCABPhA), N-(9,10-diphenyl-2-anthrayl)-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthrayl]-N,N',N'-triphenyl-1,4-phenylenediamine (abbreviated as: 2DPABPhA), 9,10-Bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), coumarin 545T, N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetraphenyl (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]vinyl}-6-methyl-4H-pyran-4-yl)malonitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H, 5H-benzo[ij]quinazine-9-yl)vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: DCM2), N,N,N',N'-tetra(4-methylphenyl)tetraphenyl-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetra(4-methylphenyl)acenaphthene[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]quinazine-9-yl)vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: DCJTI) ), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinazin-9-yl)vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]vinyl}-4H-pyran-4-ylidene)malonium (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinazin-9-yl)vinyl]-4H-pyran-4-ylidene}malonium (abbreviation: BisDCJTM) ), N,N'-diphenyl-N,N'-(1,6-pyrene-diyl)bis[(6-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03), N,N'-diphenyl-N,N'-bis[(9-phenyl-9H-carbazole-2-yl)]naphtho[2,3-b;6,7-b']bisbenzofuran-3,10-diamine (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, 1,6FLPAPrn, 1,6mMemFLPAPrn, 1,Fused aromatic diamine compounds, such as pyrene diamine compounds like 6BnfAPrn-03, possess high hole-trapping ability, high luminescence efficiency, and high reliability, making them a preferred choice.

[0169] In addition, 5,9-diphenyl-5H,9H-[1,4]benzozaborane[2,3,4-kl]phenazaborane (abbreviated: DABNA-1), 9-(diphenyl-3-yl)-N,N,5,11-tetraphenyl-5,9-dihydro-5,9-diaza-13b-borazanaphtho[3,2,1-de]anthracene-3-amine (abbreviated: DABNA-2), and 2,12-bis(tert-butyl)-5,9-bis(4-tert-butylphenyl)-N,N-diphenyl-5H,9H-[1,4]benzozaborane[2,3,4-kl] can be used appropriately. Fenrazaboron-7-amine (abbreviation: DPhA-tBu4DABNA), 2,12-di(tert-butyl)-N,N,5,9-tetra(4-tert-butylphenyl)-5H,9H-[1,4]benzozaborono[2,3,4-kl]benzozaboron-7-amine (abbreviation: tBuDPhA-tBu4DABNA), 2,12-di(tert-butyl)-5,9-di(4-tert-butylphenyl)-7-methyl-5H,9H-[1,4]benzozaborono[2,3,4-kl]phenrazaboron (abbreviation: Me-tBu4DABNA), N 7 N 7 N 13 N 13 Fused heteroaromatic compounds containing nitrogen and boron, such as 5,9,11,15-octaphenyl-5H,9H,11H,15H-[1,4]benzozaboron[2,3,4-kl][1,4]benzozaboron[4',3',2':4,5][1,4]benzozaboron[3,2-b]phenazaboron-7,13-diamine (abbreviation: ν-DABNA), 2-(4-tert-butylphenyl)benzo[5,6]indole[3,2,1-jk]benzo[b]carbazole (abbreviation: tBuPBibc), especially compounds with a diaza-boron-naphtho-anthracene skeleton, can produce blue luminescence with good color purity due to their narrow emission spectrum.

[0170] In addition to the above, compounds with an indole skeleton, such as 9,10,11-tris[3,6-bis(1,1-dimethylethyl)-9H-carbazole-9-yl]-2,5,15,18-tetra(1,1-dimethylethyl)indole[3,2,1-de]indole[3',2',1':8,1][1,4]benzozaboron[2,3,4-kl]phenazaboron (abbreviated as: BBCz-G) and 9,11-bis[3,6-bis(1,1-dimethylethyl)-9H-carbazole-9-yl]-2,5,15,18-tetra(1,1-dimethylethyl)indole[3,2,1-de]indole[3',2',1':8,1][1,4]benzozaboron[2,3,4-kl]phenazaboron (abbreviated as: BBCz-Y), are also suitable.

[0171] When a phosphorescent material is used as a luminescent material in a light-emitting layer, the following materials can be cited as examples of phosphorescent materials.

[0172] Examples include organometallic iridium complexes with a 4H-triazole skeleton, such as {2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviated as [Ir(mpptz-dmp)3]) and tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazole)iridium(III) (abbreviated as [Ir(Mptz)3]). Compounds; organometallic iridium complexes with a 1H-triazole skeleton, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazole]iridium(III) (abbreviated as [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazole)iridium(III) (abbreviated as [Ir(Prptz1-Me)3]); fac-tris[1-(2,6-diisopropyl] [Ir(iPrpim)3][3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviated as [Ir(dmpimpt-Me)3]), [2-{1-[2,6-bis(1-methylethyl)phenyl]-1H-imidazo-2-yl-κ] Organometallic iridium complexes with an imidazole skeleton, such as N3}-4-cyanophenyl-κC)iridium(III) (abbreviated as CNImIr); organometallic complexes with a benzimidazole skeleton, such as tris[(6-tert-butyl-3-phenyl-2H-imidazo[4,5-b]pyrazin-1-yl-κC2)phenyl-κC]iridium(III) (abbreviated as [Ir(cb)3]); and bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2Iridium(III) tetra(1-pyrazolyl)borate (abbreviated as: FIr6), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2 '] Iridium(III) pyridine carboxylate (abbreviated as: FIRpic), bis{2-[3',5'-bis(trifluoromethyl)phenyl]pyridinium-N,C 2 Iridium(III)pyridinecarboxylate (abbreviated as: [Ir(CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyridinium-N,C 2 Organometallic iridium complexes such as iridium(III) acetylacetone (abbreviated: FIracac) with phenylpyridine derivatives having electron-withdrawing groups as ligands; and platinum complexes such as (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC2]phenoxy-κC2}-9-(4-tert-butyl-2-pyridyl-κN)carbazole-2,1-diyl-κC1)platinum(II) (abbreviated: PtON-TBBI). These substances are compounds that emit blue phosphorescence and have emission peaks in the wavelength region of 450 nm to 520 nm. Additionally, compounds in which a portion of the hydrogen is deuterium can also be used.

[0173] In addition, examples include: tris(4-methyl-6-phenylpyrimidine)iridium(III) (abbreviated as [Ir(mppm)3]), tris(4-tert-butyl-6-phenylpyrimidine)iridium(III) (abbreviated as [Ir(tBuppm)3]), (acetylacetonate)bis(6-methyl-4-phenylpyrimidine)iridium(III) (abbreviated as [Ir(mppm)2(acac)]), (acetylacetonate)bis(6-tert-butyl-4-phenylpyrimidine)iridium(III) (abbreviated as [Ir(tBuppm)2(acac)]), (acetylacetonate)bis[6-(2-norborneol)-4-phenylpyrimidine]iridium(III) (abbreviated as [Ir(nbppm)2(acac)]), (acetylacetonate)bis[5-methyl Organometallic iridium complexes with a pyrimidine skeleton, such as 6-(2-methylphenyl)-4-phenylpyrimidinium-iridium(III) (abbreviated as [Ir(mpmppm)2(acac)]) and (acetylacetonium-ionium)bis(4,6-diphenylpyrimidinium-ionium(III)) (abbreviated as [Ir(dppm)2(acac)]); organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonium-ionium)bis(3,5-dimethyl-2-phenylpyrazine-ionium(III)) (abbreviated as [Ir(mppr-Me)2(acac)]) and (acetylacetonium-ionium)bis(5-isopropyl-3-methyl-2-phenylpyrazine-ionium(III)) (abbreviated as [Ir(mppr-iPr)2(acac)]); tris(2-phenylpyridinium-N,C2’ Iridium (III) (abbreviated as: [Ir(ppy)3]), bis(2-phenylpyridinium-N,C) 2’ Iridium (III) acetylacetone (abbreviated as: [Ir(ppy)2(acac)]), bis(benzo[h]quinoline)iridium (III) acetylacetone (abbreviated as: [Ir(bzq)2(acac)]), tri(benzo[h]quinoline)iridium (III) (abbreviated as: [Ir(bzq)3]), tri(2-phenylquinoline-N,C 2’ Iridium (III) (abbreviated as: [Ir(pq)3]), bis(2-phenylquinoline-N,C) 2’ Iridium(III)acetylacetone (abbreviated as: [Ir(pq)2(acac)]), [2-d3-methyl-8-(2-pyridyl-κN)benzofurano[2,3-b]pyridyl-κC]bis[2-(5-d3-methyl-2-pyridyl-κN) 2[Ir(5mppy-d3)2(mbfpypy-d3)], {[2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridyl-κN]benzofurano[2,3-b]pyridin-7-yl-κC]}bis[5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC]iridium(III) (abbreviated as: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-(methyl-d3)-8-(2-pyridinyl-κN)benzofurano[2,3-b]pyridin-κC]bis[2 [-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mbfpypy-d3)]), [2-(4-methyl-5-phenyl-2-pyridyl-κN)phenyl-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(mdppy)]), [2-(4-d3-methyl-5-phenyl-2-pyridyl-κN2)phenyl-κC]bis[2-(5-d3-methyl-2-pyridyl-κN2)phenyl-κC]iridium(III) (abbreviation: [Ir(5mppy-d3)2(mdppy-d3)]), [2-methyl -8-(2-pyridyl-κN)benzofurano[2,3-b]pyridin-κC]bis[2-(2-pyridyl-κN)phenyl-κC]iridium(III) (abbreviated as: [Ir(ppy)2(mbfpypy)]), tri{2-[5-(methyl-d3)-4-phenyl-2-pyridyl-κN]phenyl-κC}iridium(III) (abbreviated as: Ir(5m4dppy-d3)3) and other organometallic iridium complexes with a pyridine skeleton; tri(acetylacetonate)(monophenanthroline)terbium(III) (abbreviated as: [Tb(acac)3(Phen)]) and other rare earth metal complexes; and (2-{1-(5-tert-butylbiphenyl-2-yl)- Organometallic platinum complexes such as 4-[3-tert-butyl-5-(4-phenyl-2-pyridinyl-κN)phenyl-κC6]-2-benzimidazolyl-κN3}-4,6-di-tert-butylphenol-κO]platinum(II) (abbreviated as Pt(tBudppymmtBubiz-tBubp)) and [2-(4-(3,5-di-tert-butylphenyl)-6-{3-[4-(5'-tert-butyl[1,1':3',1''-triphenyl]-2'-yl)-2-pyridinyl-κN]phenyl-κC2}-2-pyridinyl-κN)phenol-κO]platinum(II) (abbreviated as Pt(4tButpppypyp-mmtBup)) are examples. These substances are primarily compounds exhibiting green phosphorescence and a emission peak in the 500 nm to 600 nm wavelength region.Furthermore, organometallic iridium complexes with a pyrimidine skeleton are particularly preferred due to their exceptionally high reliability or luminescence efficiency. Alternatively, compounds containing a portion of deuterium as hydrogen can also be used.

[0174] In addition, examples of organogolds with pyrimidine skeletons include: (diisobutyrylmethane)bis[4,6-bis(3-methylphenyl)pyrimidinyl]iridium(III) (abbreviated as: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinyl](dineopentaylmethane)iridium(III) (abbreviated as: [Ir(5mdppm)2(dpm)]), and bis[4,6-bis(naphth-1-yl)pyrimidinyl](dineopentaylmethane)iridium(III) (abbreviated as: [Ir(d1npm)2(dpm)]). Organometallic iridium complexes with a pyrazine skeleton, such as (acetylacetonate)bis(2,3,5-triphenylpyrazine)iridium(III) (abbreviated as [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazine)(dinepentanoylmethane)iridium(III) (abbreviated as [Ir(tppr)2(dpm)]), and (acetylacetonate)bis[2,3-bis(4-fluorophenyl)quinoxaloline]iridium(III) (abbreviated as [Ir(Fdpq)2(acac)]); tris(1-phenylisoquinoline-N,C 2’ Iridium (III) (abbreviated as: [Ir(piq)3]), bis(1-phenylisoquinoline-N,C) 2’Organometallic iridium complexes with a pyridine skeleton include iridium(III) acetylacetone (abbreviated as: [Ir(piq)2(acac)]), (3,7-diethyl-4,6-nonanedione-κO4,κO6)bis[2,4-dimethyl-6-[7-(1-methylethyl)-1-isoquinolinyl-κN]phenyl-κC]iridium(III), (3,7-diethyl-4,6-nonanedione-κO4,κO6)bis[2,4-dimethyl-6-[5-(1-methylethyl)-2-quinolinyl-κN]phenyl-κC]iridium(III). The compounds include platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (abbreviated as PtOEP); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato) (monopraninol) europium(III) (abbreviated as [Eu(DBM)3(Phen)]) and tris[1-(2-thiophenecarboxyl)-3,3,3-trifluoroacetone] (monopraninol) europium(III) (abbreviated as [Eu(TTA)3(Phen)]). These substances are red phosphorescent compounds with emission peaks in the 600 nm to 700 nm wavelength region. Furthermore, organometallic iridium complexes with a pyrazine skeleton can achieve red emission with good colorimetry. Additionally, compounds containing a portion of deuterium as hydrogen can also be used.

[0175] In addition to the phosphorescent compounds mentioned above, other known phosphorescent compounds may also be used.

[0176] Fullerenes and their derivatives, acridines and their derivatives, and eosin derivatives can be used as TADF materials. In addition, metal porphyrins containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd) can also be used. Examples of metalloporphyrins include, for instance, protoporphyrin-tin fluoride complexes represented by the following structural formulas: protoporphyrin-tin fluoride complex (SnF2(Proto IX)), mesotoporphyrin-tin fluoride complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (SnF2(Hemato IX)), tetramethyl coprophyrin-tin fluoride complex (SnF2(Copro III-4Me), octaethylporphyrin-tin fluoride complex (SnF2(OEP)), protoporphyrin-tin fluoride complex (SnF2(Etio I)), and octaethylporphyrin-platinum chloride complex (PtCl2OEP).

[0177] [Chemical Formula 1]

[0178]

[0179] In addition, 2-(biphenyl-4-yl)-4,6-bis(12-phenylindol[2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviated as: PIC-TRZ), 9-(4,6-diphenyl-1,3,5-triazin-2-yl)-9'-phenyl-9H,9'H-3,3'-bicarbazole (abbreviated as: PCCzTzn), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as: PCCzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1, Heterocyclic compounds such as 3,5-triazine (PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-oxanthracene-9-one (ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridin)phenyl]sulfone (DMAC-DPS), and 10-phenyl-10H,10'H-spiro[acridin-9,9'-anthracene]-10'-one (ACRSA) possessing one or both π-electron-rich and π-electron-deficient heterocyclic rings are preferred. These heterocyclic compounds exhibit high electron and hole transport properties due to the presence of both π-electron-rich and π-electron-deficient heterocyclic rings. Among the skeletons with π-electron-deficient heteroaromatic rings, pyridine, diazine (pyrimidine, pyrazine, pyridazine), and triazine skeletons are stable and reliable, and are therefore preferred. In particular, benzofuran-pyrimidine, benzothiophene-pyrimidine, benzofuran-pyrazine, and benzothiophene-pyrazine skeletons are highly acceptor and reliable, and are therefore preferred. Furthermore, among the skeletons with π-electron-rich heteroaromatic rings, acridine, phenoxazine, phenothiazine, furan, thiophene, and pyrrole skeletons are stable and reliable, and are therefore preferred to have at least one of these skeletons. Moreover, dibenzofuran skeletons are preferred as furan skeletons, and dibenzothiophene skeletons are preferred as thiophene skeletons. As pyrrole skeletons, indole, carbazole, indolecarbazole, bicarbazole, and 3-(9-phenyl-9H-carbazole-3-yl)-9H-carbazole skeletons are particularly preferred. In substances where π-electron-rich and π-electron-deficient heteroaromatic rings are directly bonded, the electron-donating property of the π-electron-rich heteroaromatic ring and the electron-accepting property of the π-electron-deficient heteroaromatic ring are both high, while S... 1 Energy level and T 1A smaller energy difference between energy levels allows for efficient acquisition of thermally activated delayed fluorescence, making it particularly preferred. Note that aromatic rings bonded with electron-withdrawing groups such as cyano groups can also be used instead of π-electron-deficient heteroaromatic rings. Furthermore, aromatic amine skeletons, phenazine skeletons, etc., can be used as π-electron-rich skeletons. Additionally, oxanthracene skeletons, thioxanthene dioxide skeletons, oxadiazole skeletons, triazole skeletons, imidazole skeletons, anthraquinone skeletons, boron-containing skeletons such as phenylborane or boranthrene, aromatic or heteroaromatic rings with nitrile or cyano groups such as benzonitrile or cyanobenzene, carbonyl skeletons such as benzophenone, phosphine oxide skeletons, sulfone skeletons, etc., can be used as π-electron-deficient and π-electron-rich skeletons to replace at least one of the π-electron-deficient and π-electron-rich heteroaromatic rings.

[0180] [Chemical Formula 2]

[0181]

[0182] TADF materials refer to materials with a small energy difference between the S1 and T1 levels and the ability to convert triple excitation energy into single excitation energy through antisystem crossing. Therefore, they can upconvert triple excitation energy into single excitation energy (antisystem crossing) with minimal thermal energy and efficiently generate singlet excited states. Furthermore, triple excitation energy can be converted into luminescence.

[0183] Exciplexes formed by two substances in an excited state have the function of converting triple excitation energy into single excitation energy due to the extremely small energy difference between the S1 and T1 energy levels.

[0184] Note that the phosphorescence spectrum observed at low temperatures (e.g., 77K to 10K) can be used as an indicator of the T1 energy level. For TADF materials, it is preferable that the energy difference between S1 and T1 is 0.3 eV or less, more preferably 0.2 eV or less, when the wavelength energy of the extrapolated line obtained by drawing a tangent at the tail of the short-wavelength side of the fluorescence spectrum is taken as the S1 energy level and the wavelength energy of the extrapolated line obtained by drawing a tangent at the tail of the short-wavelength side of the phosphorescence spectrum is taken as the T1 energy level.

[0185] Furthermore, when using TADF material as the luminescent material, the S1 energy level of the host material is preferably higher than that of the TADF material. Additionally, the T1 energy level of the host material is preferably higher than that of the TADF material.

[0186] As the main material of the light-emitting layer, various carrier transport materials such as materials with electron transport properties and / or materials with hole transport properties, the aforementioned TADF materials, etc., can be used.

[0187] As a material with hole transport capabilities, organic compounds having an amine skeleton or a π-electron-rich heteroaromatic ring skeleton are preferred. The π-electron-rich heteroaromatic ring is preferably a fused aromatic ring comprising at least one of an acridine skeleton, a phenoxazine skeleton, a phenothiazine skeleton, a furan skeleton, a thiophene skeleton, and a pyrrole skeleton; specifically, a carbazole ring, a dibenzothiophene ring, or a ring fused with an aromatic ring or a heteroaromatic ring.

[0188] Such hole-transporting organic compounds preferably have at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. In particular, they can be aromatic amines having substituents including a dibenzofuran ring or a dibenzothiophene ring, aromatic monoamines including a naphthyl ring, or aromatic monoamines in which a 9-fluorenyl group is bonded to the nitrogen of the amine via an arylene group. Note that when these hole-transporting organic compounds are substances including N,N-bis(4-biphenyl)amino groups, long-lifetime light-emitting devices can be manufactured, and therefore they are preferred.

[0189] Examples of the aforementioned organic compounds include: 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-4,4'-diaminobiphenyl (TPD), N,N'-bis(9,9'-spirobis[9H-fluorene]-2-yl)-N,N'-diphenyl-4,4'-diaminobiphenyl (BSPB), 4-phenyl-4'-(9-phenylfluorene-9-yl)triphenylamine (BPAFLP), 4-phenyl-3'-(9-phenylfluorene-9-yl)triphenylamine (mBPAFLP), 4-phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (PCBA1BP), 4 Compounds with aromatic amine skeletons, such as 4'-diphenyl-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCCNBB), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]fluorene-2-amine (abbreviation: PCBAF), and N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9'-spirodi[9H-fluorene]-2-amine (abbreviation: PCBASF);1,3-Bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-bis(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 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: BisBPCz), 9-(biphenyl-3-yl)-9'-(biphenyl-4-yl)-9H,9'H-3,3'-bicarbazole (abbreviation: Named as: mBPCCBP), 9-(2-naphthyl)-9'-phenyl-3,3'-bi-9H-carbazole (abbreviated as: βNCCP), 9-(3-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as: βNCCmBP), 9-(4-biphenyl)-9'-(2-naphthyl)-3,3'-bi-9H-carbazole (abbreviated as: βNCCBP), 9,9'-di-2-naphthyl-3,3'-9H,9'H-bicarbazole (abbreviated as: BisβNCz), 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-( 2-Naphthyl)-9'-[1,1':3',1''-terphenyl]-3-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-5'-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':4',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, 9-(2-naphthyl)-9'-(triphenyl-2-yl)-3,3'-9H, Compounds with a carbazole skeleton, such as 9'H-bicarbazole, 9-phenyl-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole (abbreviated as PCCzTp), 9,9'-bis(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(4-biphenyl)-9'-(triphenyl-2-yl)-3,3'-9H,9'H-bicarbazole, 9-(triphenyl-2-yl)-9'-[1,1':3',1''-terphenyl]-4-yl-3,3'-9H,9'H-bicarbazole, and 9-[3-(triphenylsilyl)phenyl]-3,9′-bi-9H-carbazole (abbreviated as PSiCzCz);Compounds with a thiophene skeleton, such as 4,4',4''-(benzyl-1,3,5-triyl)tris(dibenzothiophene) (abbreviated as DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]dibenzothiophene (abbreviated as DBTFLP-III), and 4-[4-(9-phenyl-9H-fluorene-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviated as DBTFLP-IV); and compounds with a furan skeleton, such as 4,4',4''-(benzyl-1,3,5-triyl)tris(dibenzofuran) (abbreviated as DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluorene-9-yl)phenyl]phenyl}dibenzofuran (abbreviated as mmDBFFLBi-II). Compounds with an aromatic amine backbone or a carbazole backbone are preferred due to their good reliability and high hole transport capacity, which helps reduce the driving voltage. Alternatively, organic compounds with hole transport capacity, such as those used as hole transport layers, can also be used. Furthermore, organic compounds with amine and fluorene backbones are more preferred. Organic compounds with amine and fluorene backbones have high reliability and high hole transport capacity, thus reducing the power consumption of the light-emitting device.

[0190] As a material with electron transport properties, it is preferable to use a material with an electron mobility of 1×10⁻⁶ when the square root of the electric field strength [V / cm] is 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2 Substances with a value of / Vs or higher. Furthermore, any substance other than those mentioned above may be used, provided that its electron transport capacity is higher than its hole transport capacity.

[0191] As materials with electron transport properties, preferred materials include, for example, metal complexes such as tris(8-hydroxyquinoline)aluminum (Alq3), bis(10-hydroxybenzo[h]quinoline)beryllium(II) (BeBq2), bis(2-methyl-8-hydroxyquinoline)(4-phenylphenol)aluminum(III) (BAlq), bis(8-hydroxyquinoline)zinc(II) (Znq), bis[2-(2-benzoxazolyl)phenol]zinc(II) (ZnPBO), and bis[2-(2-benzothiazolyl)phenol]zinc(II) (ZnBTZ), as well as organic compounds including π-electron-deficient heteroaromatic rings. Examples of organic compounds with π-electron-deficient heteroaromatic skeletons include organic compounds containing heteroaromatic rings with polyazole skeletons, organic compounds containing heteroaromatic rings with pyridine skeletons, organic compounds containing heteroaromatic rings with diazine skeletons, and organic compounds containing heteroaromatic rings with triazine skeletons.

[0192] Organic compounds containing heteroaromatic rings with a diazine (pyrimidine, pyrazine, or pyridazine) skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, or organic compounds containing heteroaromatic rings with a triazine skeleton are preferred due to their good reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton exhibit high electron transport properties, which helps to reduce the driving voltage. Furthermore, benzofuran-pyrimidine skeletons, benzothiophene-pyrimidine skeletons, benzofuran-pyrazine skeletons, and benzothiophene-pyrazine skeletons are preferred due to their high acceptor activity and reliability.

[0193] Examples of organic compounds with π-electron-deficient heteroaromatic ring skeletons include: 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 3-(4-biphenyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (TAZ), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl)phenyl]-9H-carbazole (CO11), 2,2',2''-(1,3,5-phenyltriyl)tris(1-phenyl-1H-benzimidazole) (TPBI), 2-[ Organic compounds with an azole skeleton, such as 3-(dibenzothiophene-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOs), 2-{4-[9,10-di(2-naphthyl)-2-anthrayl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN); 3,5-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tris[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), phenanthrene-2-phenylene (abbreviation: Bphen), copper hydroxide (abbreviation: BCP), 2,9-di(naphthyl-2-phenylene) 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviated as NBphen), 2-[3-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as mPPhen2P), 2-[3-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as mTpPPhen), 2-phenyl-9-(2-triphenylene)-1,10-phenanthroline (abbreviated as Ph-TpPhen), 2-[4-(9-phenanthyl)-1-naphthyl]-1,10-phenanthroline (abbreviated as PnNPhen), 2-[4-(2-triphenylene)phenyl]-1,10-phenanthroline (abbreviated as pTpPPhen), etc., containing heteroaromatic rings with a pyridine skeleton, are among the following. Organic compounds; 2-{3-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}dibenzo[f,h]quinoxaline (abbreviation: 2mPCCzPDBq), 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-carbazole-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4'-(9-phenyl-9H-carbazole-3-yl)-3,1'-Biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 2-[4-(3,6-diphenyl-9H-carbazole-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 9-[3'-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1',2':4,5]furano[2,3-b]pyrazine (abbreviation: 9mDBtB) PNfpr), 9-[3'-(dibenzothiophene-4-yl)biphenyl-4-yl]naphtho[1',2':4,5]furano[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 4,6-bis[3-(phenanthrene-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(dibenzothiophene-4-yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazole-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 9,9'-[pyrimidine-4,6-diylbis(biphenyl-3,3'-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophene-4-yl)phenyl]-[1]benzofurano[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 3,8-bis[3-(dibenzothiophene-4-yl)phenyl]benzofurano[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 11-[3'-(dibenzothiophene-4-yl)biphenyl-3-yl]phenanthro[9',10':4,5]furano[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr), 4,8-bis[3-(dibenzothiophene-4-yl)phenyl]-[1]benzofurano[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2B) fpm), 8-[3'-(dibenzothiophene-4-yl)[biphenyl-3-yl]naphtho[1',2':4,5]furano[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), 8-([(2,2'-binaphthyl)]-6-yl)-4-[3-(dibenzothiophene-4-yl)phenyl]-[1]benzofurano[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm), 2,2'-(pyridin-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2'-(pyridin-2,6-diyl)bis{4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 2,6-bis(4-naphthyl-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 4-[3,5-bis(9H-carbazole-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), 8-(biphenyl-4-yl)-4-[3'-(dibenzothiophene-4-yl)biphenyl-3-yl]-[1]benzofurano[3,2-d]pyrimidine (abbreviation: 8BP-4m DBtBPBfpm), 8-(p-terphenyl-3-yl)-4-[3-(dibenzothiophene-4-yl)phenyl]-[1]benzofuran[3,2-d]pyrimidine (abbreviation: 8mpTP-4mDBtPBfpm), 7-[4-(9-phenyl-9H-carbazol-2-yl)quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz) and other organic compounds with diazine skeletons; 2-(biphenyl-4-yl)-4-phenyl-6-(9,9'-spirobis[9H-fluorene]-2-yl)-1,3,5-triazine (abbreviation: BP-SFTzn), 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-8-yl)phenyl 2-{3-[3-(benzo[b]naphtho[1,2-d]furan-6-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTzn), 2-{4-[3-(N-phenyl-9H-carbazole-3-yl)-9H-carbazole-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9'-phenyl-2,3'-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 2- [3'-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indo[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-{3-[3-(dibenzothiophene-4-yl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: mDBtBPTzn), 2,4,6-tris[3'-(pyridin-3-yl)biphenyl-3-yl]-1,3,5-triazine (abbreviation: TmPPPyTz), 2-[3-(2,[6-Dimethyl-3-pyridyl)-5-(9-phenanthyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenyl-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), 2-[3'-(triphenyl-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (Abbreviation: mTpBPTzn), 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''-tert-phenyl]-4-yl)-1-dibenzofuranyl]-1,3,5-triazine (Abbreviation: mBP-TPDBfTzn), 2-(3'',5',5''-tri-tert-butyl-[1,1 [3',1''-Triphenyl]-4-yl)-4,6-diphenyl-1,3,5-triazine (abbreviation: mmtBumTPTzn-04), 2,4,6-tris[3'-(pyridin-3-yl)-5'-tert-butyl-biphenyl-3-yl]-1,3,5-triazine (abbreviation: tBu-TmPPPyTz), 2,4,6-tris[3'-(pyrimidin-3-yl)-5'-tert-butyl-biphenyl-4-yl]-1,3,5-triazine (abbreviation: tBu-TmPPPyTz-02) Organic compounds containing heteroaromatic rings with a triazine skeleton, such as 2-(3'',5',5''-tri-tert-butyl-[1,1':3',1''-terphenyl]-5-yl)-4,6-diphenyl-1,3,5-triazine (abbreviated as mmtBumTPTzn-03) and 2-{3-(2,6-dimethylpyridin-3-yl)-5-[(3,5-di-tert-butyl)phenyl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviated as mmtBuPh-mDMePyPTzn), are preferred. Furthermore, organic compounds containing heteroaromatic rings with a diazine skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, or organic compounds containing heteroaromatic rings with a triazine skeleton are preferred due to their high reliability. In particular, organic compounds containing heteroaromatic rings with diazine (pyrimidine or pyrazine) skeletons and organic compounds containing heteroaromatic rings with triazine skeletons exhibit high electron transport properties, which helps to reduce the driving voltage. Among them, 8BP-4mDBtBPBfpm, 4,6mDBTP2Pm-II, 8mpTP-4mDBtPBfpm, TPBI, ZADN, BP-ICz(II)Tzn, mmtBumTPTzn-04, tBu-TmPPPyTz, tBu-TmPPPyTz-02, mmtBumTPTzn-03, mmtBuPh-mDMePyPTzn, 4,8mDBtP2Bfpm, and Alq3 are organic compounds with large GSP-slope in vapor-deposited films, and are therefore suitable as materials for the second electron transport layer of the light-emitting device of this invention.

[0194] As a TADF material that can be used as the host material, the same materials mentioned above as TADF materials can be used. When a TADF material is used as the host material, the triple excitation energy generated by the TADF material is converted into a single excitation energy via antisystem crossing and further transferred to the luminescent material, thereby improving the luminous efficiency of the light-emitting device. In this case, the TADF material acts as an energy donor, and the luminescent material acts as an energy acceptor.

[0195] This is highly effective when the luminescent material is a fluorescent luminescent material. Furthermore, to obtain high luminescent efficiency, the S1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent luminescent material. Additionally, the T1 energy level of the TADF material is preferably higher than the S1 energy level of the fluorescent luminescent material. Therefore, the T1 energy level of the TADF material is preferably higher than the T1 energy level of the fluorescent luminescent material.

[0196] Furthermore, it is preferable to use a TADF material that exhibits luminescence with a wavelength overlapping the absorption band on the lowest energy side of the fluorescent luminescent material. This allows for efficient transfer of excitation energy from the TADF material to the fluorescent luminescent material, resulting in highly efficient luminescence, and is therefore preferred.

[0197] To efficiently generate a singlet excitation energy from a triplet excitation energy via antisystem crossing, it is preferable to induce carrier recombination within the TADF material. Furthermore, it is preferable that the triplet excitation energy generated in the TADF material does not transfer to the triplet excitation energy of the fluorescent luminescent material. For this purpose, the fluorescent luminescent material preferably has a protecting group surrounding the luminescent body (the backbone that causes luminescence) of the fluorescent luminescent material. This protecting group is preferably a substituent without π bonds, preferably a saturated hydrocarbon; specifically, examples include alkyl groups with 3 or more but less than 10 carbon atoms, cyclic alkyl groups with 3 or more but less than 10 substituted or unsubstituted carbon atoms, and trialkylsilyl groups with 3 or more but less than 10 carbon atoms; more preferably, multiple protecting groups are preferred. Substituents without π bonds have almost no function in transporting charge carriers, so they have little effect on charge carrier transport or recombination, allowing the TADF material and the luminescent body of the fluorescent luminescent material to be kept apart. Here, the luminescent body refers to the atomic group (backbone) in the fluorescent luminescent material that causes luminescence. The luminescent material preferably has a π-bonded framework, preferably containing an aromatic ring, and even more preferably having a fused aromatic ring or a fused heteroaromatic ring. Examples of such luminescent materials include phenanthrene, stilbene, acridinone, phenoxazine, phenothiazine, naphthalene, anthracene, fluorene, β-carbamate, triphenylene, tetraphenylene, pyrene, perylene, coumarin, quinacridone, and naphthobisbenzofuran frameworks. In particular, fluorescent luminescent materials having naphthalene, anthracene, fluorene, β-carbamate, triphenylene, tetraphenylene, pyrene, perylene, coumarin, quinacridone, and naphthobisbenzofuran frameworks exhibit high fluorescence quantum yields and are therefore preferred.

[0198] When using fluorescent luminescent materials as the luminescent material, materials with a benzo[a]benzene backbone, especially an anthracene backbone, are preferred as the host material. By using an anthracene backbone as the host material of the fluorescent luminescent material, a luminescent layer with high luminous efficiency and durability can be achieved. Among the anthracene backbone materials used as host materials, those with a diphenylanthracene backbone, especially 9,10-diphenylanthracene, are chemically stable and therefore preferred. Furthermore, when the host material has a carbazole backbone, hole injection / transport is improved, which is also preferred. In the case of a benzo[a]carbazole backbone with a benzene ring fused to the carbazole backbone, its HOMO (Highest Occupied Molecular Orbital) energy level is about 0.1 eV higher than that of a host material with a carbazole backbone, facilitating hole injection, which is even more preferable. In particular, when the host material has a dibenzo[a]carbazole backbone, its HOMO energy level is about 0.1 eV higher than that of a host material with a carbazole backbone, not only facilitating hole injection but also improving hole transport and heat resistance, which is also preferred. Therefore, a further preferred material for use as the host material is one having a 9,10-diphenylanthracene skeleton and a carbazole skeleton (or a benzo[a]carbazole skeleton or a dibenzo[a]carbazole skeleton). Note that from the viewpoint of hole injection / transportation described above, a benzo[a]fluorene skeleton or a dibenzo[a]fluorene skeleton can also be used instead of a carbazole skeleton.

[0199] Examples of such substances include 9-phenyl-3-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole (abbreviated: PCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviated: PCPN), 9-[4-(10-phenyl-9-anthrayl)phenyl]-9H-carbazole (abbreviated: CzPA), 7-[4-(10-phenyl-9-anthrayl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviated: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthrayl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviated: 2mBnfPPA), 9-phenyl-10-[4-(9-phenyl-9H-fluorene-9-yl)- Biphenyl-4'-yl]-anthracene (abbreviated as: FLPPA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviated as: αN-βNPAnth), 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviated as: α,βADN), 2-(10-phenylanthracene-9-yl)dibenzofuran, 2-(10-phenyl-9-anthrayl)-benzo[b]naphtho[2,3-d]furan (abbreviated as: Bnf(II)PhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviated as: βN-mβNPAnth), 1-{4-[10-(biphenyl-4-yl)-9-anthrayl]phenyl}-2-ethyl-1H-benzimidazole (abbreviated as: EtBImPBPhA), etc. In particular, CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good properties and are therefore preferred.

[0200] Furthermore, the host material can also be a mixture of multiple substances. When using a mixed host material, it is preferable to mix materials with electron transport properties and materials with hole transport properties. By mixing materials with electron transport properties and materials with hole transport properties, it is easier to adjust the transport properties of the light-emitting layer 113 and to control the composite region more easily. The weight ratio of the content of the hole transport material and the electron transport material can be from 1:19 to 19:1.

[0201] Note that phosphorescent materials can be used as part of the above-described mixture. When used as a fluorescent material, the phosphorescent material can be used as an energy donor to supply excitation energy to the fluorescent material.

[0202] Furthermore, these mixed materials can also be used to form excimer complexes. By selecting a combination of excimer complexes that emit light with wavelengths overlapping the absorption band on the lowest energy side of the luminescent material, energy transfer can be facilitated, resulting in efficient luminescence, which is therefore preferred. Furthermore, this structure allows for a reduction in the driving voltage, making it also preferred.

[0203] Note that at least one of the materials forming the excitocomplex can be a phosphorescent material. This allows for the efficient conversion of the triple excitation energy into a single excitation energy via an antisystem crosstalk.

[0204] Regarding the combination of materials for efficiently forming excitocomplexes, the HOMO energy level of the hole-transporting material is preferably above the HOMO energy level of the electron-transporting material. Furthermore, the LUMO (Lowest Unoccupied Molecular Orbital) energy level of the hole-transporting material is preferably above the LUMO energy level of the electron-transporting material. Note that the LUMO and HOMO energy levels of the material can be determined from the electrochemical properties (reduction potential and oxidation potential) of the material measured by cyclic voltammetry (CV).

[0205] Note that the formation of excitocomplexes can be confirmed, for example, by comparing the emission spectra of a hole-transporting material, the emission spectra of an electron-transporting material, and the emission spectra of a hybrid film formed by mixing these materials. When the emission spectrum of the hybrid film is observed to shift towards a longer wavelength (or to have a new peak at a longer wavelength) compared to the emission spectra of each material, it indicates the formation of an excitocomplex. Alternatively, by comparing the transient photoluminescence (PL) of a hole-transporting material, the transient PL of an electron-transporting material, and the transient PL of a hybrid film formed by mixing these materials, when a difference in transient response is observed, such as the mixed film having a longer lifetime component or a higher ratio of delayed components compared to the transient PL lifetimes of each material, it indicates the formation of an excitocomplex. Furthermore, the aforementioned transient PL can be referred to as transient electroluminescence (EL). In other words, by comparing the transient EL of a hole-transporting material, the transient EL of an electron-transporting material, and the transient EL of a hybrid film of these materials, and observing the differences in transient responses, the formation of an excitocomplex can be confirmed.

[0206] Electron transport layer 114 is a layer containing a material with electron transport properties. Preferably, the material with electron transport properties has an electron mobility of 1×10⁻⁶ when the square root of the electric field strength [V / cm] is 600. -7 cm 2 / Vs or more, preferably 1×10 -6 cm 2Substances with a value of / Vs or higher. Furthermore, any substance other than those described above may be used, as long as its electron transport capability is higher than its hole transport capability. As the aforementioned organic compounds, organic compounds having a π-electron-deficient heteroaromatic ring are preferred. For example, one or more of the following are preferred: organic compounds containing a heteroaromatic ring with a polyazole skeleton, organic compounds containing a heteroaromatic ring with a pyridine skeleton, organic compounds containing a heteroaromatic ring with a diazine skeleton, and organic compounds containing a heteroaromatic ring with a triazine skeleton.

[0207] As an organic compound with electron transport properties that can be used in the electron transport layer 114, the same organic compounds with electron transport properties that can be used in the light-emitting layer 113 can be used. Among them, organic compounds containing heteroaromatic rings with a diazine skeleton, organic compounds containing heteroaromatic rings with a pyridine skeleton, and organic compounds containing heteroaromatic rings with a triazine skeleton are preferred because they have good reliability. In particular, organic compounds containing heteroaromatic rings with a diazine (pyrimidine or pyrazine) skeleton and organic compounds containing heteroaromatic rings with a triazine skeleton have high electron transport properties, which helps to reduce the driving voltage. In particular, organic compounds with a phenanthroline skeleton, such as mTpPPhen, PnNPhen, and mPPhen2P, are preferred, and organic compounds with a phenanthroline dimer structure, such as mPPhen2P, have excellent stability and are therefore more preferred.

[0208] Note that the electron transport layer 114 may also have a stacked structure. The layer in the electron transport layer 114 that is in contact with the light-emitting layer 113 can also be used as a hole blocking layer. When the electron transport layer in contact with the light-emitting layer is used as a hole blocking layer, it is preferable to use a material whose HOMO energy level is more than 0.5 eV lower than the HOMO energy level of the material in the light-emitting layer 113.

[0209] As the electron injection layer 115, a compound or complex containing an alkali metal or alkaline earth metal such as 8-hydroxyquinoline-lithium (Liq) or a layer containing 1,1'-pyridine-2,6-diyl-bis(1,3,4,6,7,8-hexahydro-2H-pyrimidino[1,2-a]pyrimidine) (hpp2Py) may also be provided. As the electron injection layer 115, an alkali metal or alkaline earth metal or its compound may also be included in a layer formed using a substance with electron transport properties.

[0210] In addition, a charge generation layer 116 can be provided instead of an electron injection layer 115. Figure 5AThe charge generation layer 116 is a layer that, by applying a potential, can inject holes into the layer in contact with the cathode side of the layer and inject electrons into the layer in contact with the anode side of the layer. The charge generation layer 116 includes at least a p-type layer 117. The p-type layer 117 is preferably formed using the composite material that constitutes the hole injection layer 111 described above. Alternatively, the p-type layer 117 can also be formed by laminating a film containing an acceptor material as described in the composite material description and a film containing a hole transport material. By applying a potential to the p-type layer 117, electrons and holes are injected into the electron transport layer 114 and the cathode, respectively, causing the light-emitting device to operate. In addition, one embodiment of the present invention uses an organic compound with a low refractive index, and by using it in the p-type layer 117, a light-emitting device with good external quantum efficiency can be obtained.

[0211] In addition to the p-type layer 117, the charge generation layer 116 preferably includes one or both of the electron relay layer 118 and the electron injection buffer layer 119.

[0212] The electron relay layer 118 contains at least an electron-transporting material and is capable of preventing the interaction between the electron injection buffer layer 119 and the p-type layer 117, while facilitating electron transfer. Preferably, the LUMO energy level of the electron-transporting material contained in the electron relay layer 118 is set between the LUMO energy level of the acceptor material in the p-type layer 117 and the LUMO energy level of the material contained in the layer in the electron transport layer 114 that contacts the charge-generating layer 116. Specifically, the LUMO energy level of the electron-transporting material in the electron relay layer 118 is -5.0 eV or higher, preferably -5.0 eV or higher and -3.0 eV or lower. Furthermore, phthalocyanine materials or metal complexes having metal-oxygen bonds and aromatic ligands are preferably used as the electron-transporting material in the electron relay layer 118.

[0213] The electron injection buffer layer 119 can use alkali metals, alkaline earth metals, rare earth metals and their compounds (alkali metal compounds (including oxides such as lithium oxide, halides, carbonates such as lithium carbonate or cesium carbonate), alkaline earth metal compounds (including oxides, halides, carbonates) or rare earth metal compounds (including oxides, halides, carbonates)) and other materials with high electron injection properties.

[0214] Furthermore, when the electron injection buffer layer 119 contains both electron transport and donor materials, the donor materials can be alkali metals, alkaline earth metals, rare earth metals, and compounds of these materials (alkali metal compounds (including oxides, halides, and carbonates such as lithium oxide or cesium carbonate), alkaline earth metal compounds (including oxides, halides, and carbonates), or rare earth metal compounds (including oxides, halides, and carbonates)). Organic compounds such as tetrathianaphthacene (TTN), nickel-cadmium, and decamethylnickel-cadmium can also be used. Additionally, the electron transport material can be the same material described above for the electron transport layer 114.

[0215] The second electrode 102 is an electrode that includes a cathode. The second electrode 102 may also have a stacked structure, in which case the layer in contact with the EL layer 103 is used as the cathode. As the material forming the cathode, metals, alloys, conductive compounds, and mixtures thereof with low work functions (specifically below 3.8 eV) can be used. Specific examples of such cathode materials include alkali metals such as lithium (Li) or cesium (Cs), elements belonging to Group 1 or Group 2 of the periodic table such as magnesium (Mg), calcium (Ca), or strontium (Sr), alloys containing them (MgAg, AlLi), compounds (lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc.), rare earth metals such as europium (Eu) and ytterbium (Yb), and alloys containing them. However, by providing an electron injection layer 115 or a thin film of a material with a small work function between the second electrode 102 and the electron transport layer, various conductive materials such as Al, Ag, ITO, indium oxide-tin oxide containing silicon or silicon oxide, etc., can be used as cathodes regardless of the size of the work function.

[0216] When the second electrode 102 is made of a material that is transparent to visible light, a light-emitting device that emits light from one side of the second electrode 102 can be formed.

[0217] These conductive materials can be formed using dry methods such as vacuum evaporation and sputtering, as well as inkjet printing and spin coating. Alternatively, they can be formed using wet methods such as sol-gel or wet methods using pastes of metallic materials.

[0218] Furthermore, various methods, whether dry or wet, can be used to form the EL layer 103. For example, vacuum evaporation, gravure printing, offset printing, screen printing, inkjet printing, or spin coating can also be used.

[0219] In addition, the electrodes or layers described above can also be formed by using different deposition methods.

[0220] Next, refer to Figure 5B This describes a light-emitting device (also called a stacked device or tandem device) with a structure having multiple light-emitting units stacked together. This light-emitting device has multiple light-emitting units between the anode and cathode. Each light-emitting unit has a... Figures 1A to 2B The structure is roughly the same as that of EL layer 103 shown. That is to say, it can be said that... Figure 5B The light-emitting device shown is a light-emitting device with multiple light-emitting units, while Figures 1A to 2B The light-emitting device shown is a light-emitting device with one light-emitting unit.

[0221] exist Figure 5B In this structure, a first light-emitting unit 511 and a second light-emitting unit 512 are stacked between the first electrode 501 and the second electrode 502, and a charge-generating layer 513 is disposed between the first light-emitting unit 511 and the second light-emitting unit 512. The first electrode 501 and the second electrode 502 respectively correspond to... Figures 1A to 2B The first electrode 101 and the second electrode 102 are used in the process, and can be applied to... Figures 1A to 2B The same material as described. Furthermore, the first light-emitting unit 511 and the second light-emitting unit 512 may have the same structure or different structures.

[0222] The charge generation layer 513 has the function of injecting electrons into one light-emitting unit and holes into another light-emitting unit when a voltage is applied to the first electrode 501 and the second electrode 502. In other words, in Figure 5B In this process, when a voltage is applied such that the potential of the anode is higher than that of the cathode, the charge generation layer 513 can inject electrons into the first light-emitting unit 511 and inject holes into the second light-emitting unit 512.

[0223] The charge generation layer 513 preferably has the same as Figure 5A The charge generation layer 116 shown has the same structure. Because the composite material of organic compound and metal oxide has good carrier injection and carrier transport properties, it is possible to achieve low voltage drive and low current drive.

[0224] Note that when the surface of the light-emitting unit on the anode side is in contact with the charge generation layer 513, the charge generation layer 513 can function as the hole injection layer of the light-emitting unit, so the light-emitting unit may not have a hole injection layer.

[0225] In addition, when an electron injection buffer layer 119 is provided in the charge generation layer 513, since the electron injection buffer layer 119 has the function of an electron injection layer in the light-emitting unit on the anode side, it is not necessary to provide an electron injection layer in the light-emitting unit on the anode side.

[0226] Although Figure 5BThe description includes a light-emitting device with two light-emitting units, but similarly, light-emitting devices with three or more light-emitting units stacked can be applied. As in the light-emitting device according to this embodiment, by separating and arranging multiple light-emitting units between a pair of electrodes using a charge-generating layer 513, the device can achieve high brightness emission while maintaining low current density, and can also achieve a long lifespan. Furthermore, a light-emitting device capable of low-voltage driving and low power consumption can be realized.

[0227] Furthermore, by making the emission colors of each light-emitting unit different, the desired color of emission can be obtained from the entire light-emitting device. For example, by obtaining red and green emission colors from the first light-emitting unit and blue emission color from the second light-emitting unit in a light-emitting device with two light-emitting units, a light-emitting device that emits white light throughout the entire device can be obtained.

[0228] Furthermore, the aforementioned EL layer 103, first light-emitting unit 511, second light-emitting unit 512, charge-generating layer, and electrodes can be formed using methods such as vapor deposition (including vacuum vapor deposition), droplet jetting (also known as inkjet printing), coating, and gravure printing. Additionally, they may contain low-molecular-weight materials, medium-molecular-weight materials (including oligomers and dendritic polymers), or high-molecular-weight materials.

[0229] Implementation Method 3

[0230] In this embodiment, an example is described of using a light-emitting device according to one aspect of the present invention as a display element of a display device. In this embodiment, the shape of the light-emitting device is shown to be formed using photolithography, but the light-emitting device can also be formed using methods such as high-precision metal masks.

[0231] like Figure 6A and Figure 6B As shown, multiple light-emitting devices 130 are formed on the insulating layer 175 and constitute a display device.

[0232] The display device 100 includes a pixel section 177 in which a plurality of pixels 178 are arranged in a matrix. The pixels 178 include sub-pixels 110R, 110G, and 110B.

[0233] In this specification, for example, when describing the common content among subpixels 110R, 110G, and 110B, they are sometimes referred to as subpixel 110. Similarly, when describing the common content among other constituent elements distinguished by letters, symbols with omitted letters are sometimes used.

[0234] Subpixel 110R emits red light, subpixel 110G emits green light, and subpixel 110B emits blue light. Thus, an image can be displayed on pixel unit 177. In this embodiment, a subpixel of three colors—red (R), green (G), and blue (B)—is used as an example, but combinations of other colors of subpixels can also be used. Furthermore, the number of subpixels is not limited to three; four or more can be used. Examples of four subpixels include: a subpixel of four colors—R, G, B, and white (W); a subpixel of four colors—R, G, B, and yellow (Y); and a subpixel of four colors—R, G, B, and infrared (IR); etc.

[0235] In this specification, the row direction is sometimes referred to as the X direction and the column direction as the Y direction. The X direction and the Y direction intersect, for example, by perpendicular intersection.

[0236] exist Figure 6A In the example shown, subpixels of different colors are arranged in the X direction, and subpixels of the same color are arranged in the Y direction. Note that it is also possible to arrange subpixels of different colors in the Y direction and subpixels of the same color in the X direction.

[0237] A connecting portion 140 may be provided on the outer side of the pixel portion 177, and a region 141 may also be provided thereon. The region 141 is provided between the pixel portion 177 and the connecting portion 140. An EL layer 103 is provided in the region 141. In addition, a conductive layer 151C is provided on the connecting portion 140.

[0238] exist Figure 6A In the example shown, region 141 and connecting portion 140 are located to the right of pixel portion 177, but there are no particular restrictions on the position of region 141 and connecting portion 140. Furthermore, region 141 and connecting portion 140 may be one or more.

[0239] Figure 6B It is along Figure 6A An example of a cross-sectional view of the dashed-dot line A1-A2 in the diagram. For example... Figure 6B As shown, the display device includes an insulating layer 171, a conductive layer 172 on the insulating layer 171, an insulating layer 173 on the insulating layer 171 and the conductive layer 172, an insulating layer 174 on the insulating layer 173, and an insulating layer 175 on the insulating layer 174. The insulating layer 171 is disposed on a substrate (not shown). The insulating layers 175, 174, and 173 are provided with openings leading to the conductive layer 172, and a plug 176 is disposed such that it is inserted into the openings.

[0240] In the pixel section 177, a light-emitting device 130 is disposed on the insulating layer 175 and the plug 176. Furthermore, a protective layer 131 is disposed to cover the light-emitting device 130. A substrate 120 is bonded to the protective layer 131 by a resin layer 122. Additionally, an inorganic insulating layer 125 and an insulating layer 127 on the inorganic insulating layer 125 are preferably disposed between adjacent light-emitting devices 130.

[0241] Figure 6B The cross-sections of the plurality of inorganic insulating layers 125 and the plurality of insulating layers 127 are shown, but when viewed from above the display device, the inorganic insulating layers 125 and the insulating layers 127 are preferably formed as a connected layer. That is, the inorganic insulating layers 125 and the insulating layers 127 are preferably insulating layers having openings on the first electrode.

[0242] exist Figure 6B Light-emitting devices 130R, 130G, and 130B are shown as light-emitting devices 130. The light-emitting colors of light-emitting devices 130R, 130G, and 130B are different from each other. For example, light-emitting device 130R can emit red light, light-emitting device 130G can emit green light, and light-emitting device 130B can emit blue light. Alternatively, light-emitting devices 130R, 130G, or 130B can also emit other visible or infrared light. Note that in... Figure 6B In this context, light-emitting devices 130R and 130G, as well as light-emitting devices 130G and 130B, can be referred to as adjacent light-emitting devices.

[0243] One aspect of the display device of the present invention may have a top emission structure that emits light in a direction opposite to that of the substrate on which the light-emitting device is formed. Alternatively, one aspect of the display device of the present invention may also have a bottom emission structure.

[0244] The light-emitting device 130R is a light-emitting device that emits red light (preferably phosphorescence), and preferably has the structure shown in Embodiment 2. The light-emitting device 130R includes a first electrode (pixel electrode) 101R composed of conductive layers 151R and 152R, a first layer 135R on the first electrode 101R, a common layer 136 on the first layer 135R, and a second electrode (common electrode) 102 on the common layer 136. The common layer 136 is preferably an electron injection layer.

[0245] The light-emitting device 130G is a green light-emitting device (preferably phosphorescent), and preferably has the structure shown in Embodiment 2. The light-emitting device 130G includes a first electrode (pixel electrode) 101G composed of conductive layers 151G and 152G, a first layer 135G on the first electrode 101G, a common layer 136 on the first layer 135G, and a second electrode (common electrode) 102 on the common layer 136. The common layer 136 is preferably an electron injection layer.

[0246] The light-emitting device 130B is a light-emitting device that emits blue light (preferably fluorescence), and preferably has the structure shown in Embodiment 2. The light-emitting device 130B includes a first electrode (pixel electrode) 101B composed of conductive layers 151B and 152B, a first layer 135B on the first electrode 101B, a common layer 136 on the first layer 135B, and a second electrode (common electrode) 102 on the common layer 136. The common layer 136 is preferably an electron injection layer.

[0247] In a light-emitting device, one of the pixel electrode (first electrode) and the common electrode (second electrode) is used as the anode, and the other is used as the cathode. In this embodiment, unless otherwise specified, it is sometimes assumed that the pixel electrode is used as the anode and the common electrode is used as the cathode.

[0248] The first layers 135R, 135G, and 135B are arranged independently in an island shape according to each light-emitting device or each light-emitting color. Note that the first layers 135R, 135G, and 135B preferably do not overlap with each other. Sometimes, the first layer including the multiple light-emitting devices 130 formed in the light-emitting device, such as the first layers 135R, 135G, and 135B, is collectively referred to as the first layer group 135A. By arranging the first layer group 135A in an island shape for each light-emitting device 130, leakage current between adjacent light-emitting devices 130 can be suppressed even in high-definition display devices. As a result, crosstalk can be prevented to achieve a display device with extremely high contrast. In particular, a display device with high current efficiency at low brightness can be achieved.

[0249] The island-shaped first layer group 135A is formed by depositing an EL film according to the emission color and processing the EL film using photolithography.

[0250] The first layer 135 is preferably provided in such a way that it covers the top surface and side surface of the first electrode 101 (pixel electrode) of the light-emitting device 130. This makes it easier to increase the aperture ratio of the display device compared to a structure where the end of the first layer 135 is located inside the end of the pixel electrode. Furthermore, by covering the side surface of the pixel electrode of the light-emitting device 130 with the first layer 135, contact between the first electrode 101 and the second electrode 102 can be suppressed, thus preventing short circuits in the light-emitting device 130.

[0251] In one aspect of the display device of the present invention, the first electrode 101 (pixel electrode) of the light-emitting device preferably has a stacked structure. For example, in Figure 6B In the example shown, the first electrode 101 of the light-emitting device 130 has a stacked structure of a conductive layer 151 disposed on one side of the insulating layer 171 and a conductive layer 152 disposed on one side of the organic compound layer.

[0252] As the conductive layer 151, a metallic material can be used, for example. Specifically, 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), neodymium (Nd), and alloys thereof can be used.

[0253] As the conductive layer 152, an oxide containing one or more of indium, tin, zinc, gallium, titanium, aluminum, and silicon can be used. For example, conductive oxides including one or more of indium oxide, indium tin oxide, indium zinc oxide, zinc oxide, gallium-containing zinc oxide, titanium oxide, gallium-containing indium zinc oxide, aluminum-containing indium zinc oxide, silicon-containing indium tin oxide, and silicon-containing indium zinc oxide are preferred. In particular, silicon-containing indium tin oxide has a large work function, for example, 4.0 eV or more, so it is suitable for use as the conductive layer 152.

[0254] Conductive layer 151 and conductive layer 152 may each have a stacked structure containing multiple layers of different materials. In this case, conductive layer 151 may also include a layer using a material that can be used in conductive layer 152, such as a conductive oxide, and conductive layer 152 may also include a layer using a material that can be used in conductive layer 151, such as a metallic material. For example, when conductive layer 151 has a stacked structure of two or more layers, the layer in contact with conductive layer 152 may be a layer using a material that can be used in conductive layer 152.

[0255] The ends of the conductive layer 151 preferably have a tapered shape. Specifically, the ends of the conductive layer 151 preferably have a tapered shape with a taper angle of less than 90°. In this case, the conductive layer 152 disposed along the side of the conductive layer 151 also has a tapered shape. By making the ends of the conductive layer 152 tapered, the coverage of the first layer 135 disposed along the side of the conductive layer 152 can be improved.

[0256] Implementation Method 4

[0257] This embodiment describes a display device according to one aspect of the present invention.

[0258] The display device in this embodiment can be a high-definition display device. Therefore, for example, the display device in this embodiment can be used as the display unit of information terminal devices (wearable devices) such as watch-type and bracelet-type devices, as well as the display unit of wearable devices that can be worn on the head, such as VR (Virtual Reality) devices such as head-mounted displays (HMDs) and AR (Augmented Reality) devices such as glasses-type devices.

[0259] Furthermore, the display device in this embodiment can be a high-resolution display device or a large-screen display device. Therefore, the display device in this embodiment can be used, for example, as a display unit for devices such as: electronic devices with large screens, such as television sets, desktop or laptop personal computers, monitors for computers, digital signage, and large game machines such as pinball machines; digital cameras; digital video cameras; digital photo frames; mobile phones; portable game consoles; portable information terminals; and sound reproduction devices.

[0260] [Display Module]

[0261] Figure 7A A perspective view of display module 280 is shown. Display module 280 includes display device 100A and FPC 290. Note that the display device included in display module 280 is not limited to display device 100A, but may be any of display devices 100B to 100E, which will be described later.

[0262] The display module 280 includes a substrate 291 and a substrate 292. The display module 280 includes a display section 281. The display section 281 is the image display area in the display module 280, and can display light from each pixel disposed in the pixel section 284.

[0263] Figure 7B This is a three-dimensional schematic diagram of the structure on one side of the substrate 291. A circuit section 282, a pixel circuit section 283 on the circuit section 282, and a pixel section 284 on the pixel circuit section 283 are stacked on the substrate 291. Furthermore, a terminal section 285 for connecting to the FPC 290 is provided on a portion of the substrate 291 that does not overlap with the pixel section 284. The terminal section 285 is electrically connected to the circuit section 282 via a wiring section 286 composed of multiple wirings.

[0264] The pixel unit 284 includes a plurality of pixels 284a arranged periodically. Figure 7B The right side shows a magnified view of pixel 284a. Pixel 284a can adopt various structures described in the above embodiments. Figure 7B In the example, pixel 284a has the same characteristics as... Figure 6A and Figure 6B The same structure is shown for pixel 178.

[0265] The pixel circuit section 283 includes a plurality of pixel circuits 283a arranged periodically.

[0266] A pixel circuit 283a controls the driving of multiple elements included in a pixel 284a.

[0267] The circuit section 282 includes circuitry for driving each pixel circuit 283a of the pixel circuit section 283. For example, it preferably includes one or both of a gate line driving circuit and a source line driving circuit. Furthermore, it may include at least one of an arithmetic circuit, a storage circuit, and a power supply circuit.

[0268] The FPC290 is used for wiring to supply video signals or power potentials to the circuit section 282 from the outside. Furthermore, integrated circuits (ICs) can be mounted on the FPC290.

[0269] The display module 280 can adopt a structure in which one or both of the pixel circuit section 283 and the circuit section 282 are stacked on the lower side of the pixel section 284, so that the display section 281 can have an extremely high aperture ratio (effective display area ratio).

[0270] This high-definition display module 280 is suitable for use in VR devices such as HMDs or glasses-type AR devices. For example, because the display module 280 has an extremely high-definition display section 281, even when the user views the display section of the display module 280 through a lens and magnifies the display section with the lens, the pixels are not visible, thereby achieving a highly immersive display. Furthermore, the display module 280 is not limited to this and can also be applied to electronic devices with relatively small display sections.

[0271] [Display Device 100A]

[0272] Figure 8A The display device 100A shown includes a substrate 301, light-emitting devices 130R, 130G, 130B, a capacitor 240, and a transistor 310.

[0273] Substrate 301 is equivalent to Figure 7A and Figure 7BThe substrate 291 is used in the transistor 310. The transistor 310 is a transistor having a channel formation region in the substrate 301. The substrate 301 can be, for example, a semiconductor substrate such as a single-crystal silicon substrate. The transistor 310 includes a portion of the substrate 301, a conductive layer 311, a low-resistance region 312, an insulating layer 313, and an insulating layer 314. The conductive layer 311 serves as the gate electrode. The insulating layer 313 is located between the substrate 301 and the conductive layer 311 and serves as the gate insulating layer. The low-resistance region 312 is a region in the substrate 301 doped with impurities and serves as the source or drain. The insulating layer 314 covers the sides of the conductive layer 311.

[0274] In addition, a component separation layer 315 is provided between two adjacent transistors 310 in a manner embedded in the substrate 301.

[0275] In addition, an insulating layer 261 is provided to cover the transistor 310, and a capacitor 240 is provided on the insulating layer 261.

[0276] The capacitor 240 includes a conductive layer 241, a conductive layer 245, and an insulating layer 243 located therebetween. The conductive layer 241 serves as one electrode in the capacitor 240, the conductive layer 245 serves as the other electrode in the capacitor 240, and the insulating layer 243 serves as the dielectric of the capacitor 240.

[0277] A conductive layer 241 is disposed on an insulating layer 261 and embedded within an insulating layer 254. The conductive layer 241 is electrically connected to one of the source and drain terminals of the transistor 310 via a connector 271 embedded in the insulating layer 261. An insulating layer 243 is disposed to cover the conductive layer 241. A conductive layer 245 is disposed in the region where it overlaps with the conductive layer 241, separated by the insulating layer 243.

[0278] An insulating layer 255 is provided to cover the capacitor 240, and an insulating layer 174 is provided on the insulating layer 255. Light-emitting devices 130R, 130G, and 130B are provided on the insulating layer 175. Insulators are provided in the areas between adjacent light-emitting devices.

[0279] An insulating layer 156R is provided such that it includes a region overlapping the side surface of conductive layer 151R; an insulating layer 156G is provided such that it includes a region overlapping the side surface of conductive layer 151G; and an insulating layer 156B is provided such that it includes a region overlapping the side surface of conductive layer 151B. Furthermore, a conductive layer 152R is provided such that it covers conductive layer 151R and insulating layer 156R; a conductive layer 152G is provided such that it covers conductive layer 151G and insulating layer 156G; and a conductive layer 152B is provided such that it covers conductive layer 151B and insulating layer 156B. A sacrificial layer 158R is located on the first layer 135R, a sacrificial layer 158G is located on the first layer 135G, and a sacrificial layer 158B is located on the first layer 135B.

[0280] Conductive layers 151R, 151G, and 151B are electrically connected to one of the source and drain terminals of transistor 310 via plugs 256 embedded in insulating layers 243, 255, 174, and 175, conductive layer 241 embedded in insulating layer 254, and plug 271 embedded in insulating layer 261. The plugs can be made of various conductive materials.

[0281] Furthermore, a protective layer 131 is provided on the light-emitting devices 130R, 130G, and 130B. A resin layer 122 is attached to the protective layer 131 to bond the substrate 120. Detailed descriptions of the components of the light-emitting devices 130 and the substrate 120 can be found in Embodiment 3. The substrate 120 corresponds to... Figure 7A Substrate 292.

[0282] Figure 8B Show Figure 8A A modified example of the display device 100A shown. Figure 8B The display device shown includes a color layer 132R, a color layer 132G, and a color layer 132B, and a light-emitting device 130 has a region overlapping one of the color layers 132R, 132G, and 132B. Figure 8B In the display device shown, the light-emitting device 130 can emit white light, for example. In addition, for example, the color layer 132R, color layer 132G and color layer 132B can transmit red light, green light and blue light, respectively.

[0283] [Display device 100B]

[0284] Figure 9 A perspective view of the display device 100B is shown. Figure 10 A cross-sectional view of the display device 100C is shown.

[0285] The display device 100B has a structure that bonds substrate 352 and substrate 351. Figure 9 In the image, substrate 352 is represented by a dashed line.

[0286] The display device 100B includes a pixel unit 177, a connection unit 140, a circuit 356, and wiring 355, etc. Figure 9 An example is shown where display device 100B is equipped with IC354 and FPC353. Therefore, it is also possible to... Figure 9 The structure shown is referred to as a display module including a display device 100B, an IC (integrated circuit), and an FPC. Here, the substrate of the display device on which connectors such as the FPC are mounted, or the substrate on which the IC is mounted, is referred to as the display module.

[0287] The connecting portion 140 is disposed on the outer side of the pixel portion 177. There may be one or more connecting portions 140. In the connecting portion 140, the common electrode of the light-emitting device is electrically connected to the conductive layer, and power can be supplied to the common electrode.

[0288] For example, a scan line drive circuit can be used as circuit 356.

[0289] Wiring 355 has the function of supplying signals and power to pixel unit 177 and circuit 356. The signals and power are input to wiring 355 from the outside via FPC 353 or from IC 354.

[0290] Figure 9 An example is shown where IC 354 is mounted on substrate 351 using methods such as COG (Chip On Glass) or COF (Chip On Film). IC 354 can be, for example, an IC including scan line drive circuitry or signal line drive circuitry. Note that the display device 100B and display module do not necessarily need to have an IC mounted on them. Alternatively, the IC can be mounted on an FPC using a COF method, for example.

[0291] Figure 10 An example of a cross-section of a display device 100C including a portion of an area of ​​FPC 353, a portion of circuitry 356, a portion of pixel portion 177, a portion of connection portion 140, and a portion of an area including an end portion is shown.

[0292] [Display Device 100C]

[0293] Figure 10 The display device 100C shown includes transistors 201 and 205, a light-emitting device 130R that emits red light, a light-emitting device 130G that emits green light, and a light-emitting device 130B that emits blue light, etc., between substrates 351 and 352.

[0294] For details on light-emitting devices 130R, 130G, and 130B, please refer to Embodiment 1.

[0295] Light-emitting device 130R includes a conductive layer 224R, a conductive layer 151R on the conductive layer 224R, and a conductive layer 152R on the conductive layer 151R. Light-emitting device 130G includes a conductive layer 224G, a conductive layer 151G on the conductive layer 224G, and a conductive layer 152G on the conductive layer 151G. Light-emitting device 130B includes a conductive layer 224B, a conductive layer 151B on the conductive layer 224B, and a conductive layer 152B on the conductive layer 151B.

[0296] The conductive layer 224R is connected to the conductive layer 222b included in the transistor 205 through an opening provided in the insulating layer 214. The end of the conductive layer 151R is located outside the end of the conductive layer 224R. The insulating layer 156R is provided in such a way that it includes a region that contacts the side of the conductive layer 151R, and the conductive layer 152R is provided in such a way that it covers the conductive layer 151R and the insulating layer 156R.

[0297] The conductive layers 224G, 151G, 152G, and 156G in the light-emitting device 130G, and the conductive layers 224B, 151B, 152B, and 156B in the light-emitting device 130B, are the same as the conductive layers 224R, 151R, 152R, and 156R in the light-emitting device 130R, so detailed descriptions are omitted.

[0298] The conductive layers 224R, 224G, and 224B have recesses formed in a manner that cover the openings provided in the insulating layer 214. These recesses are filled with layer 128.

[0299] Layer 128 has the function of planarizing the recesses of conductive layers 224R, 224G, and 224B. Conductive layers 151R, 151G, and 151B, which are electrically connected to conductive layers 224R, 224G, and 224B, are disposed on conductive layers 224R, 224G, and 224B. Therefore, the area overlapping the recesses of conductive layers 224R, 224G, and 224B can also be used as a light-emitting area, which can improve the pixel aperture ratio.

[0300] Layer 128 can also be an insulating layer or a conductive layer. Various inorganic insulating materials, organic insulating materials, and conductive materials can be suitably used for layer 128. In particular, layer 128 is preferably formed using an insulating material, and more preferably using an organic insulating material. Layer 128 can, for example, use the organic insulating material described above that can be used in insulating layer 127.

[0301] A protective layer 131 is provided on light-emitting devices 130R, 130G, and 130B. The protective layer 131 and the substrate 352 are bonded together by an adhesive layer 142. A light-shielding layer 157 is provided on the substrate 352. The light-emitting device 130 can be sealed using a solid sealing structure or a hollow sealing structure, etc. Figure 10 In this configuration, the space between substrate 352 and substrate 351 is filled with adhesive layer 142, i.e., it can be filled with an inert gas (nitrogen or argon, etc.), i.e., a hollow sealed structure can be adopted. In this case, adhesive layer 142 can also be set in a frame shape so as not to overlap with the light-emitting device. Alternatively, a resin different from that used for the frame-shaped adhesive layer 142 can be used to fill the space.

[0302] Figure 10 An example is shown below: the connecting portion 140 includes a conductive layer 224C obtained by processing a conductive film identical to conductive layers 224R, 224G, and 224B; a conductive layer 151C obtained by processing a conductive film identical to conductive layers 151R, 151G, and 151B; and a conductive layer 152C obtained by processing a conductive film identical to conductive layers 152R, 152G, and 152B. Furthermore, Figure 10 An example is shown in which the insulating layer 156C is disposed in such a manner that it includes a region that overlaps with the side of the conductive layer 151C.

[0303] Display device 100C is a top-emitting display device. A light-emitting device emits light onto one side of a substrate 352. The substrate 352 is preferably made of a material with high transmittance to visible light. When the light-emitting device emits infrared or near-infrared light, a material with high transmittance to such light is preferably used. The first electrode (pixel electrode) contains a material that reflects visible light, and the second electrode (opposite electrode) contains a material that transmits visible light.

[0304] Insulating layers 211, 213, 215, and 214 are sequentially disposed on substrate 351. A portion of insulating layer 211 serves as the gate insulating layer for each transistor. A portion of insulating layer 213 serves as the gate insulating layer for each transistor. Insulating layer 215 is disposed to cover the transistor. Insulating layer 214 is disposed to cover the transistor and serves as a planarization layer. Furthermore, there is no particular limitation on the number of gate insulating layers and the number of insulating layers covering the transistor; there can be one or more.

[0305] Inorganic insulating films are preferably used as insulating layers 211, 213 and 215.

[0306] The insulating layer 214 used as the planarization layer is preferably an organic insulating layer.

[0307] Transistor 201 and transistor 205 include: a conductive layer 221 serving as a gate; an insulating layer 211 serving as a gate insulating layer; conductive layers 222a and 222b serving as source and drain; a semiconductor layer 231; an insulating layer 213 serving as a gate insulating layer; and a conductive layer 223 serving as a gate.

[0308] A connection portion 204 is provided in the region of substrate 351 that is not overlapped with substrate 352. In the connection portion 204, wiring 355 is electrically connected to FPC 353 via conductive layer 166 and connection layer 242. An example is shown where conductive layer 166 has a stacked structure consisting of a conductive film processed from the same conductive films as conductive layers 224R, 224G, and 224B; a conductive film processed from the same conductive films as conductive layers 151R, 151G, and 151B; and a conductive film processed from the same conductive films as conductive layers 152R, 152G, and 152B. Conductive layer 166 is exposed on the top surface of connection portion 204. Therefore, connection portion 204 can be electrically connected to FPC 353 via connection layer 242.

[0309] Preferably, a light-shielding layer 157 is provided on the surface of the substrate 352 on the substrate 351 side. The light-shielding layer 157 can be provided between adjacent light-emitting devices, in the connection portion 140, and in the circuit 356, etc. In addition, various optical components can be arranged on the outer side of the substrate 352.

[0310] Substrate 351 and substrate 352 may each be made of a material that can be used in substrate 120.

[0311] As the adhesive layer 142, a material suitable for the resin layer 122 can be used.

[0312] As the connecting layer 242, anisotropic conductive film (ACF) or anisotropic conductive paste (ACP) can be used.

[0313] [Display Device 100D]

[0314] Figure 11 The display device 100D shown is Figure 10 The main difference between the display device 100C and the display device 100D is that the display device 100D is a bottom-emitting type display device.

[0315] The light emitted by the light-emitting device is directed onto one side of the substrate 351. The substrate 351 is preferably made of a material with high transmittance to visible light. On the other hand, there are no restrictions on the transmittance of the material used for the substrate 352.

[0316] Preferably, a light-shielding layer 157 is formed between the substrate 351 and the transistor 201 and between the substrate 351 and the transistor 205. Figure 11 An example is shown where a light-shielding layer 157 is disposed on a substrate 351, an insulating layer 153 is disposed on the light-shielding layer 157, and transistors 201, 205, etc. are disposed on the insulating layer 153.

[0317] The light-emitting device 130R includes a conductive layer 112R, a conductive layer 126R on the conductive layer 112R, and a conductive layer 129R on the conductive layer 126R.

[0318] The light-emitting device 130B includes a conductive layer 112B, a conductive layer 126B on the conductive layer 112B, and a conductive layer 129B on the conductive layer 126B.

[0319] The conductive layers 112R, 112B, 126R, 126B, 129R, and 129B all use materials with high transmittance to visible light. A material that reflects visible light is preferably used as the second electrode.

[0320] Note that, although Figure 11 The light-emitting device 130G is not shown in the figure, but it is also provided.

[0321] in addition, Figure 11 Examples are shown where the top surface of layer 128 has a flat portion, but there are no particular restrictions on the shape of layer 128.

[0322] [Display Device 100E]

[0323] Figure 12 The display device 100E shown is Figure 10 The main difference between the display device 100E and the display device 100C is that the display device 100E includes color layer 132R, color layer 132G and color layer 132B.

[0324] In the display device 100E, the light-emitting device 130 has a region overlapping one of the coloring layers 132R, 132G, and 132B. The coloring layers 132R, 132G, and 132B can be disposed on a surface of the substrate 352 on one side of the substrate 351. The ends of the coloring layers 132R, 132G, and 132B can overlap the light-shielding layer 157.

[0325] In the display device 100E, the light-emitting device 130 can emit white light, for example. Additionally, for example, the color layers 132R, 132G, and 132B can transmit red light, green light, and blue light, respectively. Alternatively, the display device 100E may also employ a structure in which the color layers 132R, 132G, and 132B are disposed between the protective layer 131 and the adhesive layer 142.

[0326] Figure 10 and Figure 12 Examples are shown where the top surface of layer 128 has a flat portion, but there are no particular restrictions on the shape of layer 128.

[0327] This embodiment can be appropriately combined with other embodiments or examples. Furthermore, where multiple structural examples are shown in one embodiment in this specification, these structural examples can be appropriately combined.

[0328] Implementation Method 5

[0329] In this embodiment, an electronic device according to one aspect of the present invention will be described.

[0330] The electronic device of this embodiment includes a display device according to one aspect of the present invention in its display unit. The display device according to one aspect of the present invention has low power consumption. Therefore, it can be used in the display units of various electronic devices.

[0331] As electronic devices, in addition to large-screen electronic devices such as television sets, desktop or laptop personal computers, monitors for computers, digital signage, and large game machines such as pinball machines, other examples include digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, portable information terminals, and sound reproduction devices.

[0332] In particular, because the display device of one aspect of the present invention has low power consumption, it can be suitable for use in smaller electronic devices. Examples of such electronic devices include watch-type and bracelet-type information terminal devices (wearable devices), wearable devices that can be worn on the head, VR devices such as head-mounted displays, AR devices such as glasses, and MR devices.

[0333] The electronic device in this embodiment may also include a sensor (which has the function of measuring factors such as force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, tilt, vibration, odor, or infrared radiation).

[0334] Reference Figures 13A to 13D This illustrates an example of a wearable device that can be worn on the head.

[0335] Figure 13A The electronic device 700A shown and Figure 13B The electronic devices 700B shown include a pair of display panels 751, a pair of housings 721, a communication unit (not shown), a pair of mounting units 723, a control unit (not shown), an imaging unit (not shown), a pair of optical components 753, a frame 757, and a pair of nose pads 758.

[0336] The display panel 751 can be used in a display device according to one aspect of the present invention. Thus, an electronic device with low power consumption and the ability to operate for extended periods can be realized.

[0337] Both electronic devices 700A and 700B can project the image displayed by the display panel 751 onto the display area 756 in the optical component 753. Because the optical component 753 is light-transmitting, the user can see the image displayed in the display area by overlapping the image seen through the optical component 753.

[0338] Both electronic devices 700A and 700B can be equipped with cameras capable of capturing images of the front as imaging units. Furthermore, by incorporating accelerometers such as gyroscopes into both electronic devices 700A and 700B, the orientation of the user's head can be detected, and an image corresponding to that orientation can be displayed on the display area 756.

[0339] The communications unit includes a wireless communication device through which video signals can be supplied, for example. Additionally, a connector capable of connecting cables supplying video signals and power potential may be included, either in place of the wireless communication device or in addition to the wireless communication device.

[0340] In addition, electronic devices 700A and 700B are equipped with batteries that can be charged wirelessly or via wired means, or both.

[0341] The housing 721 can also be equipped with a touch sensor module.

[0342] Various touch sensors can be used as touch sensor modules. For example, capacitive, resistive, infrared, electromagnetic induction, surface acoustic wave, and optical sensors can be employed. In particular, capacitive or optical sensors are preferred for use in touch sensor modules.

[0343] Figure 13C The electronic device 800A shown and Figure 13D The electronic devices 800B shown all include a pair of display units 820, a housing 821, a communication unit 822, a pair of mounting units 823, a control unit 824, a pair of imaging units 825, and a pair of lenses 832.

[0344] The display unit 820 can be equipped with a display device according to one aspect of the present invention. This allows for the realization of an electronic device with low power consumption and the ability to operate for extended periods.

[0345] The display unit 820 is located inside the housing 821 in a position visible through the lens 832. Furthermore, by displaying different images on each of the pair of display units 820, three-dimensional display utilizing parallax can be achieved.

[0346] Electronic devices 800A and 800B preferably have a mechanism in which the left and right positions of the lens 832 and the display unit 820 can be adjusted so that the lens 832 and the display unit 820 are in the most suitable position according to the position of the user's eyes.

[0347] Users can use the mounting unit 823 to wear electronic device 800A or electronic device 800B on their heads.

[0348] The imaging unit 825 has the function of acquiring external information. The data acquired by the imaging unit 825 can be output to the display unit 820. An image sensor can be used in the imaging unit 825. In addition, multiple cameras can be set to support various viewing angles such as telephoto and wide-angle.

[0349] Electronic device 800A may also include a vibration mechanism used as a bone conduction headphone.

[0350] Electronic devices 800A and 800B may also include input terminals. Cables supplying image signals from image output devices and the like, as well as power for charging batteries installed within the electronic devices, can be connected to the input terminals.

[0351] The electronic device of one embodiment of the present invention may also have the function of wireless communication with the earphone 750.

[0352] In addition, electronic devices may also include an earphone unit. Figure 13B The illustrated electronic device 700B includes an earphone unit 727. A portion of the wiring connecting the earphone unit 727 and the control unit may also be configured inside the housing 721 or the mounting unit 723.

[0353] Similarly, Figure 13D The illustrated electronic device 800B includes an earphone unit 827. For example, a structure in which the earphone unit 827 and the control unit 824 are connected in a wired manner can be adopted.

[0354] Thus, as an embodiment of the present invention, both eyeglass type (electronic device 700A and electronic device 700B, etc.) and goggle type (electronic device 800A and electronic device 800B, etc.) are preferred electronic devices.

[0355] Figure 14A The electronic device 6500 shown is a portable information terminal device that can be used as a smartphone.

[0356] Electronic device 6500 includes a housing 6501, a display unit 6502, a power button 6503, a button 6504, a speaker 6505, a microphone 6506, a camera 6507, and a light source 6508, etc. The display unit 6502 has a touch panel function.

[0357] The display unit 6502 can use a display device according to one aspect of the present invention. This allows for the realization of an electronic device with low power consumption and the ability to operate for extended periods.

[0358] Figure 14B This is a cross-sectional schematic diagram of one end of the microphone 6506, including the housing 6501.

[0359] A light-transmitting protective member 6510 is provided on one side of the display surface of the housing 6501. The space surrounded by the housing 6501 and the protective member 6510 contains a display panel 6511, an optical member 6512, a touch sensor panel 6513, a printed circuit board 6517, a battery 6518, etc.

[0360] The display panel 6511, optical component 6512, and touch sensor panel 6513 are fixed to the protective component 6510 using an adhesive layer (not shown).

[0361] In the area outside the display unit 6502, a portion of the display panel 6511 is folded back, and this folded portion is connected to an FPC 6515. An IC 6516 is mounted on the FPC 6515. The FPC 6515 is connected to terminals disposed on a printed circuit board 6517.

[0362] The display panel 6511 can be used with a display device according to one aspect of the present invention. This allows for the realization of an extremely lightweight electronic device. Furthermore, since the display panel 6511 is extremely thin, a large-capacity battery 6518 can be installed while minimizing the thickness of the electronic device. Additionally, by folding a portion of the display panel 6511 to provide a connection portion with the FPC 6515 on the back of the pixel section, a narrow-bezel electronic device can be achieved.

[0363] Figure 14C An example of a television device is shown. In the television device 7100, a display unit 7000 is assembled in a housing 7171. Here is shown a structure in which the housing 7171 is supported by a bracket 7173.

[0364] The display unit 7000 can use a display device according to one aspect of the present invention. This allows for the realization of an electronic device with low power consumption and the ability to operate for extended periods.

[0365] It can be operated using the operating switch included in the housing 7171 and the separately provided remote control 7151. Figure 14C The operation of the television device 7100 shown.

[0366] Figure 14D An example of a notebook computer is shown. The notebook computer 7200 includes a casing 7211, a keyboard 7212, a pointing device 7213, and an external connection port 7214, etc. A display unit 7000 is assembled in the casing 7211.

[0367] The display unit 7000 can use a display device according to one aspect of the present invention. This allows for the realization of an electronic device with low power consumption and the ability to operate for extended periods.

[0368] Figure 14E and Figure 14F Here is an example of digital signage.

[0369] Figure 14E The digital sign 7300 shown includes a housing 7301, a display unit 7000, and a speaker 7303. It may also include LEDs, operation keys (including a power switch or operation switch), connection terminals, various sensors, a microphone, etc.

[0370] Figure 14F A digital sign 7400 is shown mounted on a cylindrical column 7401. The digital sign 7400 includes a display section 7000 disposed along the curved surface of the column 7401.

[0371] exist Figure 14E and Figure 14F In this embodiment, a display device according to one aspect of the present invention can be used in the display unit 7000. This allows for the realization of a highly reliable electronic device.

[0372] The larger the display unit (7000), the more information it can provide at once. A larger display unit (7000) is also more likely to attract attention, which can improve the effectiveness of advertising.

[0373] like Figure 14E and Figure 14F As shown, the digital signage 7300 or digital signage 7400 preferably can be linked with the user's smartphone or other information terminal device 7311 or information terminal device 7411 via wireless communication.

[0374] Figures 15A to 15GThe electronic device shown includes a housing 9000, a display unit 9001, a speaker 9003, operation keys 9005 (including a power switch or operation switch), a connection terminal 9006, a sensor 9007 (which has the function of measuring the following factors: force, displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, tilt, vibration, odor, or infrared radiation), a microphone 9008, etc.

[0375] Figures 15A to 15G The electronic device shown has various functions. For example, it may have the following functions: displaying various information (static images, dynamic images, or text images, etc.) on the display unit; touch panel function; displaying calendar, date, or time, etc.; controlled and processed by various software (programs); wireless communication function; reading and processing programs or data stored in the storage medium; etc.

[0376] The following is a detailed explanation. Figures 15A to 15G The electronic device shown.

[0377] Figure 15A This is a perspective view showing a portable information terminal 9171. The portable information terminal 9171 can be used, for example, as a smartphone. Note that a speaker 9003, a connection terminal 9006, a sensor 9007, etc., may also be included in the portable information terminal 9171. Furthermore, as a portable information terminal 9171, text or image information can be displayed on multiple surfaces. Figure 15A The image shows an example displaying three icons 9050. Alternatively, information 9051, shown as a dashed rectangle, can be displayed on other surfaces of the display unit 9001. Examples of information 9051 include notifications of received emails, SNS messages, or phone calls; the subject of the email or SNS message; the sender's name; the date; the time; remaining battery level; and radio wave strength. Alternatively, icons 9050 can be displayed in the same location where information 9051 is displayed.

[0378] Figure 15B This is a perspective view showing a portable information terminal 9172. The portable information terminal 9172 has the function of displaying information on three or more surfaces of the display unit 9001. Here, examples are shown where information 9052, information 9053, and information 9054 are displayed on different surfaces. For example, when the portable information terminal 9172 is placed in a jacket pocket, the user can view information 9053 displayed in a position seen from above the portable information terminal 9172.

[0379] Figure 15CThis is a perspective view of a tablet terminal 9173. The tablet terminal 9173 can, for example, execute various application software such as mobile phone, email, and article reading and editing, music playback, network communication, and computer games. The tablet terminal 9173 includes a display unit 9001, a camera 9002, a microphone 9008, and a speaker 9003 on the front of its casing 9000; operation keys 9005 serving as operating buttons on the left side of the casing 9000; and a connection terminal 9006 on the bottom surface.

[0380] Figure 15D This is a perspective view showing a watch-type portable information terminal 9200. The portable information terminal 9200 can be used, for example, as a smartwatch (registered trademark). Furthermore, the display surface of the display unit 9001 is curved, allowing display along its curved surface. In addition, the portable information terminal 9200 can perform hands-free calls, for example, by communicating with a headset capable of wireless communication. Furthermore, by utilizing the connection terminal 9006, the portable information terminal 9200 can transmit data or charge with other information terminals. Charging can also be performed wirelessly.

[0381] Figures 15E to 15G This is a perspective view showing the foldable portable information terminal 9201. Additionally, Figure 15E This is a 3D view of the portable information terminal 9201 in its unfolded state. Figure 15G It is a 3D image of the folded state. Figure 15F From Figure 15E status and Figure 15G The portable information terminal 9201 is a three-dimensional representation of the state transitioning between different states. In its folded state, it offers good portability, while in its unfolded state, it provides a large, seamless display area, resulting in excellent browsing capabilities. The display unit 9001 included in the portable information terminal 9201 is supported by three housings 9000 connected by hinges 9055. The display unit 9001 can be bent, for example, within a radius of curvature of 0.1 mm or more and 150 mm or less.

[0382] This embodiment can be appropriately combined with other embodiments or examples. Furthermore, where multiple structural examples are shown in one embodiment in this specification, these structural examples can be appropriately combined.

[0383] Example 1

[0384] In this embodiment, the detailed manufacturing methods and characteristics of light-emitting devices 1-1, 1-2, and 1-3 are described. The structural formulas of the main compounds used in this embodiment are shown below.

[0385] [Chemical Formula 3]

[0386]

[0387] (Manufacturing method of light-emitting device 1-1)

[0388] First, indium tin oxide (ITSO) containing silicon oxide is deposited on a glass substrate by sputtering to a thickness of 55 nm, thereby forming a first electrode 101 with a size of 2 mm × 2 mm. Furthermore, ITSO is used as the anode.

[0389] Next, as a pretreatment for forming light-emitting devices on the substrate, the substrate surface is washed with water.

[0390] Then, the substrate is placed inside and depressurized to 1×10⁻⁶. -4 The substrate is placed in a vacuum evaporation apparatus at approximately Pa and then calcined at 170°C for 30 minutes in the heating chamber of the apparatus, followed by cooling for approximately 30 minutes.

[0391] Next, the substrate is fixed on a support in a vacuum evaporation apparatus with the surface on which the first electrode 101 is formed facing down. A hole injection layer 111 is formed by co-evaporation on the inorganic insulating film and the first electrode 101 using N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviated as: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) and a thickness of 10 nm.

[0392] PCBBiF is deposited on the hole injection layer 111 with a thickness of 45 nm, followed by the deposition of 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviated as PSiCzCz) represented by the above structural formula (ii) with a thickness of 5 nm, thereby forming the hole transport layer 112. Note that PSiCzCz is an organic compound with a π-electron-rich heteroaromatic ring, and the PSiCzCz layer is also used as an electron blocking layer.

[0393] Next, on the hole transport layer, a light-emitting layer 113 is formed by co-depositing 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTrzCz2), PSiCzCz, and (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC2]phenoxy-κC2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC1)platinum (II) (abbreviated as PtON-TBBI) (abbreviated as PtON-TBBI) represented by the above structural formula (iii) in a weight ratio of 0.35:0.53:0.12 (=SiTrzCz2:PSiCzCz:PtON-TBBI) with a thickness of 40 nm. Note that PtON-TBBI is a blue phosphorescent organometallic complex. Furthermore, SiTrzCz2 is an organic compound with a π-electron-deficient heteroaromatic ring, and PSiCzCz is an organic compound with a π-electron-rich heteroaromatic ring.

[0394] Then, after depositing 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (mSiTrz) with a thickness of 5 nm to form the first electron transport layer, 2-{4-[9,10-bis(2-naphthyl)-2-anthrayl]phenyl}-1-phenyl-1H-benzimidazole (ZADN) and PtON-TBBI with a thickness of 30 nm and a weight ratio of 0.9:0.1 (=ZADN:PtON-TBBI) are co-deposited to form the second electron transport layer. Note that mSiTrz and ZADN are organic compounds with π-electron-deficient heteroaromatic rings, and the first electron transport layer is used as a hole-blocking layer.

[0395] After forming the electron transport layer, lithium fluoride (LiF) is deposited with a thickness of 1 nm to form the electron injection layer 115, and then aluminum (Al) is deposited with a thickness of 200 nm to form the second electrode 102 (cathode).

[0396] Next, in a glove box under a nitrogen atmosphere, a glass substrate is used to seal the light-emitting device in a manner that prevents it from being exposed to the atmosphere (a UV-curable sealing material is applied around the device, and UV is irradiated only to the sealing material without irradiating the light-emitting device, and heat treatment is performed at 80°C for 1 hour under atmospheric pressure), thereby forming the light-emitting device 1-1.

[0397] (Manufacturing method of light-emitting device 1-2)

[0398] The difference between the manufacturing methods of light-emitting device 1-2 and light-emitting device 1-1 lies in the fact that the ZADN used in the second electron transport layer of light-emitting device 1-1 is replaced with 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviated as: BP-Icz(II)Tzn) represented by the above structural formula (vii). Note that BP-Icz(II)Tzn is an organic compound with a π-electron-deficient heteroaromatic ring.

[0399] (Manufacturing method of light-emitting devices 1-3)

[0400] The difference between the manufacturing methods of light-emitting device 1-3 and light-emitting device 1-1 is that the ZADN used in the second electron transport layer of light-emitting device 1-1 is replaced with mSiTrz.

[0401] The following diagram shows the device structures of light-emitting devices 1-1, 1-2, and 1-3.

[0402] [Table 3]

[0403]

[0404] Figure 16 The brightness-current density characteristics of light-emitting devices 1-1, 1-2, and 1-3 are shown. Figure 17 The brightness-voltage characteristics are shown. Figure 18 The current efficiency-current density characteristics are shown. Figure 19 The current density-voltage characteristics are shown. Figure 20 The blue indicator shows the current density characteristic. Figure 21 The external quantum efficiency-current density characteristics are shown. Figure 22 The electroluminescence spectrum is shown. Figure 23 A chromaticity diagram is shown. Furthermore, Table 4 shows the current density at 10 mA / cm². 2 The main characteristics are as follows. Note that measurements of luminance, CIE chromaticity, and electroluminescence spectrum were performed at room temperature using a spectroradiometer (Topcon, SR-UL1R). Furthermore, the external quantum efficiency was calculated using the measured luminance and emission spectra, assuming a Lambertian distribution.

[0405] [Table 4]

[0406]

[0407] Thus, it can be seen that light-emitting devices 1-1 and 1-2 are light-emitting devices with low driving voltage and high power efficiency.

[0408] also, Figure 24 and Figure 25 It shows 10mA / cm 2 The normalized brightness time-varying characteristics and voltage time-varying characteristics are shown when the current density drives light-emitting devices 1-1, 1-2, and 1-3. Note that the normalized brightness time-varying characteristics are expressed with the initial brightness as 100%, and the voltage time-varying characteristics show the change in voltage from the initial voltage.

[0409] from Figure 24 and Figure 25 It can be seen that light-emitting devices 1-1 and 1-2 are light-emitting devices with small brightness decrease and voltage rise relative to driving time and high reliability.

[0410] Figure 44 The emission spectra (PL spectra) of single films of SiTrzCz2 and PSiCzCz and the emission spectra (PL spectra) of a mixed film with a weight ratio of SiTrzCz2:PSiCzCz = 1:1 are shown. Note that the emission spectra were measured at room temperature using films deposited on a quartz substrate with a thickness of 50 nm. A fluorophotometer (FP-8600, manufactured by Nippon Spectrophotometer Co., Ltd.) was used for the measurements. The excitation wavelengths were 330 nm (single film of SiTrzCz2), 310 nm (single film of PSiCzCz), and 355 nm (mixed film of SiTrzCz2 and PSiCzCz). Figure 44 As shown, the emission spectrum of the mixed film is located at a longer wavelength compared to the emission spectrum of each individual film, indicating that SiTrzCz2 and PSiCzCz form an excitocomplex in the mixed film. In other words, SiTrzCz2 and PSiCzCz are a combination that forms an excitocomplex.

[0411] Furthermore, Table 5 shows the GSP_Slope of the vapor-deposited films of the hole transport layers for light-emitting devices 1-1, 1-2, and 1-3, comprising organic compounds with π-electron-rich heteroaromatic rings or aromatic amines, organic compounds with π-electron-deficient heteroaromatic rings for the first electron transport layer, organic compounds with π-electron-deficient heteroaromatic rings for the second electron transport layer, and the host material for the light-emitting layers. Table 5 also shows the GSP_Slope of films formed by co-depositing the light-emitting layers using SiTrzCz2, PSiCzCz, and PtON-TBBI in a weight ratio of 0.45:0.45:0.10 (=SiTrzCz2:PSiCzCz:PtON-TBBI). In Table 5, the GSP_Slope was measured using the method shown in Embodiment 1.

[0412] [Table 5]

[0413]

[0414] Thus, in light-emitting devices 1-1 and 1-2, the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is greater than the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer. In light-emitting device 1-3, the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is the same as the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer.

[0415] Therefore, in light-emitting devices 1-1 and 1-2, a negative interface charge originating from the difference in GSP_Slope is set at the interface between the first electron transport layer and the second electron transport layer. Through this effect, electron injection from the second electrode or electron injection layer to the second electron transport layer is suppressed. As a result, the recombination region biased towards the anode side can be expanded in the light-emitting layer of a blue phosphorescent device, and the degradation of the hole transport layer, which serves as an electron blocking layer, can be reduced. Thus, the reliability of light-emitting devices 1-1 and 1-2 is improved.

[0416] Note that in the above-described light-emitting device, the GSP_Slope of the film of the host material (SiTrzCz2 and PSiCzCz) is greater than the GSP_Slope of the film of the first organic compound (mSiTrz). Furthermore, the GSP_Slope of the light-emitting layer is greater than the GSP_Slope of the first electron transport layer.

[0417] With the above structure, electron injection from the second electron transport layer to the first electron transport layer can be smoothly performed in the above-mentioned light-emitting device. Therefore, even if electron injection from the second electrode or electron injection layer to the second electron transport layer in light-emitting devices 1-1 and 1-2 is suppressed, a significant increase in driving voltage will not occur, thus enabling the realization of a light-emitting device with excellent characteristics.

[0418] Furthermore, the GSP_Slope of the films containing ZADN and BP-Icz(II)Tzn, organic compounds with π-electron-deficient heteroaromatic rings, in the second electron transport layers of light-emitting devices 1-1 and 1-2, is greater than the GSP_Slope of the films of the host materials (SiTrzCz2 and PSiCzCz). Moreover, the GSP_Slope of the second electron transport layer is greater than that of the light-emitting layer.

[0419] Therefore, the interface charge between the first electron transport layer and the second electron transport layer in light-emitting devices 1-1 and 1-2 is negative and smaller than the interface charge between the light-emitting layer and the first electron transport layer. Through this effect, electron injection from the second electrode or electron injection layer to the second electron transport layer is suppressed. Furthermore, hole injection into the light-emitting layer is promoted. As a result, the recombination region biased towards the anode side can typically be expanded in the light-emitting layer of a blue phosphorescent device, and the degradation of the hole transport layer, which serves as an electron blocking layer, can be further reduced.

[0420] Furthermore, in the aforementioned light-emitting devices, the GSP_Slope of the light-emitting layer (co-evaporated film of SiTrzCz2, PSiCzCz and PtON-TBBI) is greater than the GSP_Slope of the hole transport layer (evaporated film of PSiCzCz). Therefore, holes can be easily injected from the hole injection layer to the hole transport layer, thus enabling the realization of light-emitting devices with low driving voltages.

[0421] Thus, the light-emitting device of one aspect of the present invention can be a light-emitting device with good characteristics that has high reliability and low driving voltage.

[0422] Example 2

[0423] In this embodiment, light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b of one embodiment of the present invention are described, and detailed manufacturing methods and characteristics of comparative light-emitting devices 2-1, 2-2a, and 2-2b of comparative examples are provided. The structural formulas of the main compounds used in this embodiment are shown below.

[0424] [Chemical Formula 4]

[0425]

[0426] (Manufacturing method of light-emitting device 2-1a)

[0427] First, indium tin oxide (ITSO) containing silicon oxide is deposited on a glass substrate by sputtering to a thickness of 55 nm, thereby forming a first electrode 101 with a size of 2 mm × 2 mm. Furthermore, ITSO is used as the anode.

[0428] Next, as a pretreatment for forming light-emitting devices on the substrate, the substrate surface is washed with water.

[0429] Then, the substrate is placed inside and depressurized to 1×10⁻⁶. -4 The substrate is placed in a vacuum evaporation apparatus at approximately Pa and then calcined at 170°C for 30 minutes in the heating chamber of the apparatus, followed by cooling for approximately 30 minutes.

[0430] Next, the substrate is fixed on a support in a vacuum evaporation apparatus with the surface on which the first electrode 101 is formed facing down. A hole injection layer 111 is formed by co-evaporation on the inorganic insulating film and the first electrode 101 using N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviated as: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) and a thickness of 10 nm.

[0431] Next, PCBBiF is deposited on the hole injection layer 111 with a thickness of 45 nm, followed by the deposition of 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviated as PSiCzCz) represented by the above structural formula (ii) with a thickness of 5 nm, thereby forming the hole transport layer 112. Note that PSiCzCz is an organic compound with a π-electron-rich heteroaromatic ring, and the PSiCzCz layer is also used as an electron blocking layer.

[0432] Next, a light-emitting layer 113 is formed on the hole transport layer 112 by co-evaporation of 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTrzCz2), PSiCzCz, and (2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC2]phenoxy-κC2}-9-(4-tert-butyl-2-pyridinyl-κN)carbazole-2,1-diyl-κC1)platinum (II) (abbreviated as PtON-TBBI) (abbreviated as PtON-TBBI), represented by the above structural formula (iv). Note that PtON-TBBI is a phosphorescent organometallic complex that exhibits blue fluorescence (with peak wavelengths above 450 nm and below 520 nm). Furthermore, SiTrzCz2 is an organic compound with a π-electron-deficient heteroaromatic ring, and PSiCzCz is an organic compound with a π-electron-rich heteroaromatic ring.

[0433] Then, after depositing 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (mSiTrz) with a thickness of 5 nm to form the first electron transport layer, 2-{4-[9,10-bis(2-naphthyl)-2-anthrayl]phenyl}-1-phenyl-1H-benzimidazole (ZADN) and 8-hydroxyquinoline-lithium (Liq) with a weight ratio of 1:1 and a thickness of 30 nm are co-deposited, thereby forming the second electron transport layer. Note that mSiTrz and ZADN are organic compounds with π-electron-deficient heteroaromatic rings, Liq is an organometallic complex containing an alkali metal, and the first electron transport layer is used as a hole-blocking layer.

[0434] After forming the electron transport layer, lithium fluoride (LiF) is deposited with a thickness of 1 nm to form the electron injection layer 115, and then aluminum (Al) is deposited with a thickness of 200 nm to form the second electrode 102 (cathode).

[0435] Next, in a glove box under a nitrogen atmosphere, a glass substrate is used to seal the light-emitting device in a manner that prevents it from being exposed to the atmosphere (a UV-curable sealing material is applied around the device, and UV is irradiated only to the sealing material without irradiating the light-emitting device, and heat treatment is performed at 80°C for 1 hour under atmospheric pressure), thereby forming the light-emitting device 2-1a.

[0436] (Manufacturing method of light-emitting device 2-1b)

[0437] The difference between the manufacturing methods of light-emitting device 2-1b and light-emitting device 2-1a is that the second electron transport layer in light-emitting device 2-1a is deposited by co-evaporation of ZADN and Liq in a weight ratio of 1:4 (=ZADN:Liq).

[0438] (Manufacturing method of light-emitting device 2-2a)

[0439] The difference between the manufacturing methods of light-emitting device 2-2a and light-emitting device 2-1a lies in the fact that the ZADN in the second electron transport layer of light-emitting device 2-1a is replaced with 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviated as: BP-Icz(II)Tzn) represented by the above structural formula (vii). Note that BP-Icz(II)Tzn is an organic compound with a π-electron-deficient heteroaromatic ring.

[0440] (Manufacturing method of light-emitting device 2-2b)

[0441] The difference between the manufacturing methods of light-emitting device 2-2b and light-emitting device 2-1b is that the ZADN of the second electron transport layer in light-emitting device 2-1b is replaced with BP-Icz(II)Tzn.

[0442] (Compare the manufacturing methods of light-emitting device 2-1)

[0443] The difference between the manufacturing methods of light-emitting device 2-1 and light-emitting device 2-1a lies in the fact that the second electron transport layer in light-emitting device 2-1a is formed using 2,2'-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviated as mPPhen2P) represented by the above structural formula (ix).

[0444] (Compare the manufacturing methods of light-emitting device 2-2a)

[0445] The difference between the manufacturing methods of light-emitting device 2-2a and light-emitting device 2-1a is that the ZADN used in the second electron transport layer of light-emitting device 2-1a is replaced with mSiTrz.

[0446] (Compare the manufacturing methods of light-emitting devices 2-2b)

[0447] The difference between the manufacturing methods of light-emitting device 2-2b and light-emitting device 2-1b is that the ZADN used in the second electron transport layer of light-emitting device 2-1b is replaced with mSiTrz.

[0448] The following diagram shows the device structures of light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, as well as the comparative light-emitting devices 2-1, 2-2a, and 2-2b.

[0449] [Table 6]

[0450]

[0451] [Table 7]

[0452]

[0453] Figure 26 The brightness-current density characteristics of light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, as well as comparison light-emitting devices 2-1, 2-2a, and 2-2b, are shown. Figure 27 The brightness-voltage characteristics are shown. Figure 28 The current efficiency-current density characteristics are shown. Figure 29 The current density-voltage characteristics are shown. Figure 30 The blue indicator shows the current density characteristic. Figure 31 The external quantum efficiency-current density characteristics are shown. Figure 32 The electroluminescence spectrum is shown. Furthermore, Table 8 shows the current density at 10 mA / cm². 2 The main characteristics are as follows. Note that measurements of luminance, CIE chromaticity, and electroluminescence spectrum were performed at room temperature using a spectroradiometer (Topcon, SR-UL1R). Furthermore, the external quantum efficiency was calculated using the measured luminance and emission spectra, assuming a Lambertian distribution.

[0454] [Table 8]

[0455]

[0456] Thus, it can be seen that light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, as well as comparative light-emitting devices 2-1, 2-2a, and 2-2b, are all light-emitting devices with good characteristics.

[0457] also, Figure 33 It shows 10mA / cm 2 The time-varying characteristics of normalized luminance when the current density drives light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, and when comparing light-emitting devices 2-1, 2-2a, and 2-2b. Note that the time-varying characteristics of normalized luminance are expressed with the initial luminance as 100%.

[0458] from Figure 33 It can be seen that, compared with the comparison light-emitting device 2-1, comparison light-emitting device 2-2a and comparison light-emitting device 2-2b, light-emitting device 2-1a, light-emitting device 2-1b, light-emitting device 2-2a and light-emitting device 2-2b are light-emitting devices with smaller brightness decrease relative to driving time and higher reliability.

[0459] Figure 44 The emission spectra (PL spectra) of single films of SiTrzCz2 and PSiCzCz and the emission spectra (PL spectra) of a mixed film with a weight ratio of SiTrzCz2:PSiCzCz = 1:1 are shown. Note that the films were deposited on a quartz substrate with a thickness of 50 nm, and the emission spectra were measured at room temperature. A fluorophotometer (FP-8600, manufactured by Nippon Spectrophotometer Co., Ltd.) was used for the measurements. The excitation wavelengths were 330 nm (single film of SiTrzCz2), 310 nm (single film of PSiCzCz), and 355 nm (mixed film of SiTrzCz2 and PSiCzCz). Figure 44As shown, the emission spectrum of the mixed film is located at a longer wavelength compared to the emission spectrum of each individual film, indicating that SiTrzCz2 and PSiCzCz form an excitocomplex in the mixed film. In other words, SiTrzCz2 and PSiCzCz are a combination that forms an excitocomplex.

[0460] Table 9 shows the GSP_Slope of the vapor-deposited films of the first electron transport layer (containing π-electron-deficient heteroaromatic rings) for light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, as well as the organic compounds containing π-electron-deficient heteroaromatic rings for the second electron transport layer, the organic compounds containing π-electron-rich heteroaromatic rings or aromatic amines for the hole transport layer, and the host material for the light-emitting layer. Table 9 also shows the GSP_Slope of films formed by co-depositing the light-emitting layer using SiTrzCz2, PSiCzCz, and PtON-TBBI in a weight ratio of 0.45:0.45:0.10 (=SiTrzCz2:PSiCzCz:PtON-TBBI). In Table 9, the GSP_Slope was measured using the method shown in Embodiment 1.

[0461] [Table 9]

[0462]

[0463] Thus, in light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is greater than the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer.

[0464] On the other hand, in the comparison light-emitting device 2-1, the GSP_Slope of the film containing the organic compound with the π-electron-deficient heteroaromatic ring in the second electron transport layer is lower than that of the film containing the organic compound with the π-electron-deficient heteroaromatic ring in the first electron transport layer. In the comparison light-emitting devices 2-2a and 2-2b, the GSP_Slope of the film containing the organic compound with the π-electron-deficient heteroaromatic ring in the second electron transport layer is the same as that of the film containing the organic compound with the π-electron-deficient heteroaromatic ring in the first electron transport layer.

[0465] Here, the results of measuring the capacitance-voltage characteristics of a light-emitting device (light-emitting device 2) according to one embodiment of the present invention and a comparative light-emitting device (comparative light-emitting device 2) are shown. Light-emitting device 2 is a light-emitting device having the same structure as light-emitting device 2-2b, and comparative light-emitting device 2 is a light-emitting device having the same structure as comparative light-emitting device 2-1a. Note that the capacitance-voltage characteristics were measured using a potentiostat / galvanostat (Biologic SP-300, France), at a frequency of 10 Hz at room temperature.

[0466] Figure 34B The measurement results for comparison light-emitting device 2 are shown. From Figure 34B It can be seen that near -7.0V, electrons are injected from the electron injection layer into the second electron transport layer, and near -3.0V, electrons are injected from the second electron transport layer into the first electron transport layer.

[0467] Figure 34A These are the measurement results for light-emitting device 2. From Figure 34A It can be seen that near -1.0V, electrons are injected from the electron injection layer into the second electron transport layer, and near 0V, electrons are injected from the second electron transport layer into the first electron transport layer.

[0468] These results show that, in one aspect of the light-emitting device of the present invention, electron injection is suppressed.

[0469] Thus, electron injection into the second electron transport layer is further suppressed in light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b. Typically, in the light-emitting layer of a blue phosphorescent device, the HOMO and LUMO energy levels of the blue phosphorescent material are higher than those of the host material, thus trapping holes but not electrons, resulting in a recombination region biased towards the anode side. In a light-emitting device according to one embodiment of the present invention, by having the above-described structure, electron injection into the second electron transport layer is suppressed, thereby expanding the recombination region biased towards the anode side, which reduces the degradation of the hole transport layer used as an electron blocking layer. As a result, the reliability of light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b is improved. Note that the HOMO level of PSiCzCz, the main material used in the luminescent layer of this embodiment, is -5.7 eV and the LUMO level is -2.06 eV. The HOMO level of SiTrzCz2 is lower than that of PSiCzCz and the LUMO level is -2.98 eV. The HOMO level of PtON-TBBI, the blue phosphorescent material, is -5.50 eV and the LUMO level is -2.3 eV. Therefore, it traps holes without trapping electrons as described above.

[0470] The values ​​of the HOMO and LUMO energy levels were calculated by cyclic voltammetry (CV).

[0471] In cyclic voltammetry (CV) measurements, the values ​​(E) of the HOMO and LUMO energy levels are calculated from the oxidation peak potential (Epa) and reduction peak potential (Epc) obtained by changing the potential of the working electrode relative to the reference electrode. During the measurement, the HOMO energy level is calculated using a positive potential scan, and the LUMO energy level is calculated using a negative potential scan. Furthermore, the scan rate during the measurement is set to 0.1 V / s.

[0472] Specifically, the standard redox potential (Eo) (=(Epa+Epc) / 2) is calculated from the oxidation peak potential (Epa) and reduction peak potential (Epc) obtained from the cyclic voltammogram of the material. By subtracting Eo from the potential energy (Ex) of the reference electrode relative to the vacuum level, the values ​​(E) of the HOMO level and LUMO level can be calculated respectively (=Ex-Eo).

[0473] Note that the above shows the case where a reversible redox wave can be obtained. However, in the case where an irreversible redox wave can be obtained, the standard redox potential (Eo) to one decimal place is calculated by subtracting a fixed value (0.1 eV) from the oxidation peak potential (Epa) and assuming it to be the reduction peak potential (Epc). The HOMO level is then calculated from this. Furthermore, when calculating the LUMO level, the standard redox potential (Eo) to one decimal place is calculated by adding a fixed value (0.1 eV) to the reduction peak potential (Epc) and assuming it to be the oxidation peak potential (Epa).

[0474] Furthermore, in addition to the organic compound with a π-electron-deficient heteroaromatic ring, the second electron transport layer of light-emitting devices 2-1a, 2-1b, 2-2a, 2-2b, and the comparison light-emitting devices 2-2a and 2-2b also contains Liq, a metal complex with an alkali metal, in addition to the organic compound with a π-electron-deficient heteroaromatic ring. When the weight ratio of the organic compound with a π-electron-deficient heteroaromatic ring and Liq in the second electron transport layer is set to x:y, the value of (x+y) / x times of the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer is 20.6 (mV / nm) in light-emitting devices 2-1a, 2-2a, and the comparison light-emitting device 2-2a, and 51.5 (mV / nm) in light-emitting devices 2-1b, 2-2b, and the comparison light-emitting device 2-2b. In light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is greater than (x+y) / x times the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer. In comparison light-emitting devices 2-2a and 2-2b, the GSP_Slope is the same as or smaller than that of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer.

[0475] Thus, when the weight ratio of the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer to Liq is set to x:y, and the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is greater than (x+y) / x times the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer, the injection of electrons from the second electrode or the electron injection layer to the second electron transport layer can be suppressed, thereby providing a light-emitting device with good reliability.

[0476] Note that in the above-described light-emitting device, the GSP_Slope of the film of the host material (SiTrzCz2 and PSiCzCz) is greater than the GSP_Slope of the film of the first organic compound. Furthermore, the GSP_Slope of the light-emitting layer is greater than the GSP_Slope of the first electron transport layer.

[0477] With the above structure, a positive interface charge can be set at the interface between the light-emitting layer and the first electron transport layer, so the injection of electrons from the second electron transport layer to the first electron transport layer in the above-mentioned light-emitting device is smooth. Therefore, even if the injection of electrons into the second electron transport layer in light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b is suppressed, it will not cause a significant increase in the driving voltage, so a light-emitting device with good characteristics can be realized.

[0478] Furthermore, the GSP_Slope of the films containing ZADN and BP-Icz(II)Tzn, organic compounds with π-electron-deficient heteroaromatic rings, in the second electron transport layers of light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b, is greater than the GSP_Slope of the films of the host materials (SiTrzCz2 and PSiCzCz). Moreover, the GSP_Slope of the second electron transport layer is greater than the GSP_Slope of the light-emitting layer.

[0479] Therefore, the interface charge between the first electron transport layer and the second electron transport layer in light-emitting devices 2-1a, 2-1b, 2-2a, and 2-2b is negative and smaller than the interface charge between the light-emitting layer and the first electron transport layer. Through this effect, electron injection from the second electrode or electron injection layer to the second electron transport layer is suppressed. Furthermore, hole injection within the light-emitting layer is promoted. As a result, the recombination region biased towards the anode side can typically be expanded in the light-emitting layer of a blue phosphorescent device, and the degradation of the hole transport layer, which serves as an electron blocking layer, can be further reduced.

[0480] Furthermore, in the aforementioned light-emitting devices, the GSP_Slope of the emissive layer (co-evaporated film of SiTrzCz2, PSiCzCz, and PtON-TBBI) is greater than the GSP_Slope of the hole transport layer (evaporated film of PSiCzCz). Therefore, holes can be easily injected from the hole transport layer into the emissive layer, thus enabling the realization of light-emitting devices with low driving voltages.

[0481] Thus, the light-emitting device of one aspect of the present invention can be a light-emitting device with high reliability and good characteristics.

[0482] Example 3

[0483] In this embodiment, a detailed manufacturing method and characteristics of a light-emitting device 3 according to one aspect of the present invention and a comparative example of a light-emitting device 3 are described. The structural formulas of the main compounds used in this embodiment are shown below.

[0484] [Chemical Formula 5]

[0485]

[0486] (Manufacturing method of light-emitting device 3)

[0487] First, indium tin oxide (ITSO) containing silicon oxide is deposited on a glass substrate by sputtering to a thickness of 55 nm, thereby forming a first electrode 101 with a size of 2 mm × 2 mm. Furthermore, ITSO is used as the anode.

[0488] Next, as a pretreatment for forming light-emitting devices on the substrate, the substrate surface is washed with water.

[0489] Then, the substrate is placed inside and depressurized to 1×10⁻⁶. -4 The substrate is placed in a vacuum evaporation apparatus at approximately Pa and then calcined at 170°C for 30 minutes in the heating chamber of the apparatus, followed by cooling for approximately 30 minutes.

[0490] Next, the substrate is fixed on a support in a vacuum evaporation apparatus with the surface on which the first electrode 101 is formed facing down. A hole injection layer 111 is formed by co-evaporation on the inorganic insulating film and the first electrode 101 using N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-9,9-dimethyl-9H-fluorene-2-amine (abbreviated as: PCBBiF) represented by the above structural formula (i) and an electron acceptor material (OCHD-003) containing fluorine with a molecular weight of 672 in a weight ratio of 1:0.03 (=PCBBiF:OCHD-003) and a thickness of 10 nm.

[0491] Next, PCBBiF is deposited on the hole injection layer 111 with a thickness of 45 nm, followed by the deposition of 9-[3-(triphenylsilyl)phenyl]-3,9'-bi-9H-carbazole (abbreviated as PSiCzCz) represented by the above structural formula (ii) with a thickness of 5 nm, thereby forming the hole transport layer 112. Note that PSiCzCz is an organic compound with a π-electron-rich heteroaromatic ring, and the PSiCzCz layer is also used as an electron blocking layer.

[0492] Next, 9,9'-{6-[3-(triphenylsilyl)phenyl]-1,3,5-triazine-2,4-diyl}bis(9H-carbazole) (abbreviated as SiTrzC) represented by the above structural formula (iii) was co-deposited on the hole transport layer 112 in a weight ratio of 0.35:0.53:0.12 (=SiTrzCz2:PSiCzCz:Pt(mmtBubOcz35dm4ppy-d6)) with a thickness of 40 nm. The luminescent layer 113 is formed from the structure (x) represented by the above structural formula (x): 2-{3-[3-(3,5-di-tert-butylphenyl)benzimidazol-1-yl-2-ylidene-κC2]phenoxy-κC2}-9-[3,5-di(methyl-d3)-4-phenyl-2-pyridyl-κN]carbazole-2,1-diyl-κC)platinum(II) (abbreviated as: Pt(mmtBubOcz35dm4ppy-d6)). Note that Pt(mmtBubOcz35dm4ppy-d6) is a phosphorescent organometallic complex that exhibits blue phosphorescence (emission spectrum peak wavelength above 450 nm and below 520 nm). Furthermore, SiTrzCz2 is an organic compound with a π-electron-deficient heteroaromatic ring, and PSiCzCz is an organic compound with a π-electron-rich heteroaromatic ring.

[0493] Then, after depositing 2-phenyl-4,6-bis[3-(triphenylsilyl)phenyl]-1,3,5-triazine (abbreviated as mSiTrz) with a thickness of 5 nm to form the first electron transport layer, 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazine-2-yl]-11,12-dihydro-12-phenylindolo[2,3-a]carbazole (abbreviated as BP-Icz(II)Tzn) and 8-hydroxyquinoline-lithium (abbreviated as Liq) with a thickness of 30 nm and a weight ratio of 1:4 are co-deposited with the above structural formula (vii) to form the second electron transport layer. Note that mSiTrz and BP-Icz(II)Tzn are organic compounds with π-electron-deficient heteroaromatic rings, Liq is an organometallic complex containing an alkali metal, and the first electron transport layer is used as a hole blocking layer.

[0494] After forming the electron transport layer, lithium fluoride (LiF) is deposited with a thickness of 1 nm to form the electron injection layer 115, and then aluminum (Al) is deposited with a thickness of 200 nm to form the second electrode 102 (cathode).

[0495] Next, in a glove box under a nitrogen atmosphere, a glass substrate is used to seal the light-emitting device in a manner that prevents it from being exposed to the atmosphere (a UV-curable sealing material is applied around the device, and UV is irradiated only to the sealing material without irradiating the light-emitting device, and heat treatment is performed at 80°C for 1 hour under atmospheric pressure), thereby forming the light-emitting device 3.

[0496] (Compare the manufacturing methods of light-emitting device 3)

[0497] The difference between the light-emitting device 3 and the manufacturing method of the light-emitting device 3 is that the second electron transport layer in the light-emitting device 3 is formed by using 2,2'-(1,3-phenyl)bis(9-phenyl-1,10-phenanthroline) (abbreviated as mPPhen2P) represented by the above structural formula (ix).

[0498] The following shows the device structure of light-emitting device 3 and a comparison of light-emitting device 3.

[0499] [Table 10]

[0500]

[0501] Figure 35 The image shows the light-emitting device 3 and compares the brightness-current density characteristics of the light-emitting device 3. Figure 36 The current efficiency-current density characteristics are shown. Figure 37 The brightness-voltage characteristics are shown. Figure 38 The current density-voltage characteristics are shown. Figure 39 The blue indicator shows the current density characteristic. Figure 40 The external quantum efficiency-current density characteristics are shown. Figure 41 The electroluminescence spectrum is shown. Figure 42 The CIE chromaticity diagram is shown. Furthermore, Table 11 shows the current density at 10 mA / cm². 2 The main characteristics are as follows. Note that measurements of luminance, CIE chromaticity, and electroluminescence spectrum were performed at room temperature using a spectroradiometer (Topcon, SR-UL1R). Furthermore, the external quantum efficiency was calculated using the measured luminance and emission spectra, assuming a Lambertian distribution.

[0502] [Table 11]

[0503]

[0504] Thus, it can be seen that both light-emitting device 3 and the comparative light-emitting device 3 are light-emitting devices with good characteristics. In addition, it can be seen that light-emitting device 3 is a light-emitting device with particularly good current efficiency and external quantum efficiency.

[0505] also, Figure 43 It is shown that at 10mA / cm 2The current density driving the light-emitting device 3 and the time-varying characteristics of the normalized brightness when comparing the light-emitting device 3 are shown. Note that the time-varying characteristics of the normalized brightness are expressed with the initial brightness as 100%.

[0506] from Figure 43 It can be seen that the light-emitting device 3 is a light-emitting device with less brightness drop and higher reliability than the comparative light-emitting device 3 with respect to driving time.

[0507] Figure 44 The emission spectra (PL spectra) of single films of SiTrzCz2 and PSiCzCz and the emission spectra (PL spectra) of a mixed film with a weight ratio of 1:1 are shown. Note that the films were deposited on a quartz substrate with a thickness of 50 nm, and the emission spectra were measured at room temperature. A fluorophotometer (FP-8600, manufactured by Nippon Spectrophotometer Co., Ltd.) was used for the measurements. The excitation wavelengths were 330 nm (single film of SiTrzCz2), 310 nm (single film of PSiCzCz), and 355 nm (mixed film of SiTrzCz2 and PSiCzCz). Figure 44 As shown, the emission spectrum of the mixed film is located at a longer wavelength compared to the emission spectrum of each individual film, indicating that SiTrzCz2 and PSiCzCz form an excitocomplex in the mixed film. In other words, SiTrzCz2 and PSiCzCz are a combination that forms an excitocomplex.

[0508] Furthermore, Table 12 shows the GSP_Slope of the organic compound with a π-electron-deficient heteroaromatic ring used in the first electron transport layer of the light-emitting device 3 and the comparative light-emitting device 3, the organic compound with a π-electron-deficient heteroaromatic ring used in the second electron transport layer, the organic compound with a π-electron-rich heteroaromatic ring or aromatic amine used in the hole transport layer, and the vapor-deposited film of the host material used in the light-emitting layer. Note that in Table 12, the GSP_Slope was measured by the method shown in Embodiment 1.

[0509] [Table 12]

[0510]

[0511] Thus, in the light-emitting device 3, the GSP_Slope of the film containing the organic compound with the π-electron-deficient heteroaromatic ring contained in the second electron transport layer is greater than the GSP_Slope of the film containing the organic compound with the π-electron-deficient heteroaromatic ring contained in the first electron transport layer.

[0512] On the other hand, in the comparison light-emitting device 3, the GSP_Slope of the film containing the organic compound with the π-electron-deficient heteroaromatic ring contained in the second electron transport layer is lower than that of the film containing the organic compound with the π-electron-deficient heteroaromatic ring contained in the first electron transport layer.

[0513] Therefore, electron injection into the second electron transport layer in the light-emitting device 3 is further suppressed. Typically, in the light-emitting layer of a blue phosphorescent device, the HOMO and LUMO energy levels of the blue phosphorescent material are higher than those of the host material, thus trapping holes but not electrons, resulting in a recombination region biased towards the anode side. In a light-emitting device according to one embodiment of the present invention, by having the above-described structure, electron injection into the second electron transport layer is suppressed, thereby expanding the recombination region biased towards the anode side, which reduces the degradation of the hole transport layer used as an electron blocking layer. As a result, the reliability of the light-emitting device 3 is improved. Note that the HOMO level of PSiCzCz, the main material used in the luminescent layer of this embodiment, is -5.7 eV and the LUMO level is -2.06 eV. The HOMO level of SiTrzCz2 is lower than that of PSiCzCz and the LUMO level is -2.98 eV. The HOMO level of Pt (mmtBubOcz35dm4ppy-d6), the blue phosphorescent material, is -5.50 eV and the LUMO level is -2.47 eV. Therefore, it traps holes without trapping electrons as described above.

[0514] The values ​​of the HOMO and LUMO energy levels were calculated by cyclic voltammetry (CV) measurements. The CV measurements were performed in the same manner as described in Example 2.

[0515] Furthermore, the second electron transport layer of the light-emitting device 3 contains Liq, which is a metal complex containing an alkali metal in addition to an organic compound with a π-electron-deficient heteroaromatic ring. When the weight ratio of the organic compound with a π-electron-deficient heteroaromatic ring and Liq in the second electron transport layer of the light-emitting device 3 is set to x:y, the GSP_Slope (x+y) / x times of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer is 51.5 (mV / nm). The light-emitting device 3 is a light-emitting device in which the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is greater than the value of (x+y) / x times of the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer.

[0516] Thus, when the weight ratio of the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer to Liq is set to x:y, the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the second electron transport layer is greater than the value of (x+y) / x times the GSP_Slope of the film containing the organic compound with a π-electron-deficient heteroaromatic ring in the first electron transport layer, thereby providing a light-emitting device with better reliability.

[0517] Note that in the above-described light-emitting device, the GSP_Slope of the film of the host material (SiTrzCz2 and PSiCzCz) is greater than the GSP_Slope of the film of the first organic compound. Furthermore, the GSP_Slope of the light-emitting layer is greater than the GSP_Slope of the first electron transport layer.

[0518] With the above structure, a positive interface charge can be set at the interface between the light-emitting layer and the first electron transport layer, so the injection of electrons from the second electron transport layer to the first electron transport layer in the light-emitting device is smooth. Therefore, even if the injection of electrons into the second electron transport layer in the light-emitting device 3 is suppressed, it will not cause a significant increase in the driving voltage, thus enabling a light-emitting device with excellent characteristics.

[0519] Furthermore, the BP-Icz(II)Tzn of the organic compound with a π-electron-deficient heteroaromatic ring contained in the second electron transport layer of the light-emitting device 3 is greater than the GSP_Slope of the host material (SiTrzCz2 and PSiCzCz). Moreover, the GSP_Slope of the second electron transport layer is greater than the GSP_Slope of the light-emitting layer.

[0520] Therefore, the interface charge between the first electron transport layer and the second electron transport layer in the light-emitting device 3 is negative and smaller than the interface charge between the light-emitting layer and the first electron transport layer. Through this effect, electron injection from the second electrode or electron injection layer to the second electron transport layer is suppressed. Furthermore, hole injection within the light-emitting layer is promoted. As a result, the recombination region biased towards the anode side can typically be expanded in the light-emitting layer of a blue phosphorescent device, and the degradation of the hole transport layer, which serves as an electron blocking layer, can be further reduced.

[0521] Thus, the light-emitting device of one aspect of the present invention can be a light-emitting device with high reliability and good characteristics.

Claims

1. A light-emitting device, comprising: The first electrode on the insulating surface; A second electrode opposite to the first electrode; as well as The EL layer located between the first electrode and the second electrode, The EL layer includes a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer. The first electron transport layer is located between the light-emitting layer and the second electron transport layer. The second electron transport layer is located between the first electron transport layer and the second electrode. The light-emitting layer is located between the hole transport layer and the first electron transport layer. The GSP_Slope (mV / nm) of the second electron transport layer is greater than that of the first electron transport layer (mV / nm). Furthermore, the GSP_Slope (mV / nm) is expressed as ΔV / Δd, where ΔV (mV) is the change in surface potential for a change in thickness Δd (nm).

2. A light-emitting device, comprising: The first electrode on the insulating surface; A second electrode opposite to the first electrode; as well as The EL layer located between the first electrode and the second electrode, The EL layer includes a light-emitting layer, a hole transport layer, a first electron transport layer, and a second electron transport layer. The first electron transport layer is located between the light-emitting layer and the second electron transport layer. The second electron transport layer is located between the first electron transport layer and the second electrode. The light-emitting layer is located between the hole transport layer and the first electron transport layer. The first electron transport layer comprises a first organic compound. The second electron transport layer comprises a second organic compound. The first organic compound and the second organic compound each independently possess a π-electron-deficient heteroaromatic ring. The GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than that of the vapor-deposited film of the first organic compound. Furthermore, the GSP_Slope (mV / nm) is expressed as ΔV / Δd, where ΔV (mV) is the change in surface potential for a change in thickness Δd (nm).

3. The light-emitting device according to claim 2, The second electron transport layer also contains a first substance.

4. The light-emitting device according to claim 3, When the mixing ratio of the second organic compound and the first substance in the second electron transport layer is x:y, the GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than (x+y) / x times the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

5. The light-emitting device according to claim 4, Where y is greater than or equal to x.

6. The light-emitting device according to claim 1, The light-emitting layer contains a substance that emits phosphorescence.

7. The light-emitting device according to claim 1, The GSP_Slope (mV / nm) of the light-emitting layer is greater than the GSP_Slope (mV / nm) of the first electron transport layer.

8. The light-emitting device according to claim 7, The GSP_Slope (mV / nm) of the light-emitting layer is greater than the GSP_Slope (mV / nm) of the hole transport layer.

9. The light-emitting device according to claim 2, The light-emitting layer comprises a host material and a light-emitting substance. Furthermore, the GSP_Slope (mV / nm) of the vapor-deposited film of the host material is greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the first organic compound.

10. The light-emitting device according to claim 9, The GSP_Slope (mV / nm) of the vapor-deposited film of the second organic compound is greater than the GSP_Slope (mV / nm) of the vapor-deposited film of the host material.

11. The light-emitting device according to claim 9, The hole transport layer contains a third organic compound. Furthermore, the GSP_Slope (mV / nm) of the light-emitting layer is greater than or equal to the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound.

12. The light-emitting device according to claim 9, The hole transport layer contains a third organic compound. Furthermore, the GSP_Slope (mV / nm) of the vapor-deposited film of the main material is greater than or equal to the GSP_Slope (mV / nm) of the vapor-deposited film of the third organic compound.

13. The light-emitting device according to claim 9, The main material comprises a first material and a second material. Furthermore, the first material and the second material are organic compounds that form an excitocomplex.

14. The light-emitting device according to claim 13, The first material is an organic compound with a π-electron-deficient heteroaromatic ring. Furthermore, the second material is an organic compound having a π-electron-rich heteroaromatic ring or an aromatic amine.

15. The light-emitting device according to claim 3, The first substance is a metal complex.

16. The light-emitting device according to claim 15, The metal complex is an organic complex containing an alkali metal.

17. The light-emitting device according to claim 6, The emission spectrum of the phosphorescent material has a peak wavelength of 450 nm or higher and 520 nm or lower.

18. The light-emitting device according to claim 9, The peak wavelength of the emission spectrum of the luminescent material is above 450 nm and below 520 nm.

19. The light-emitting device according to claim 2, The light-emitting layer contains a substance that emits phosphorescence.

20. The light-emitting device according to claim 19, The emission spectrum of the phosphorescent material has a peak wavelength of 450 nm or higher and 520 nm or lower.

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