Light-emitting element

Abstract

To provide a light-emitting element with a good lifespan or a light-emitting element with good luminous efficiency. [Solution] The device has a first electrode 101, a second electrode 102, and an EL layer 103 in this order. The EL layer 103 has, from the first electrode 101 side, a hole injection layer 111, a first layer 112-1 having a first hole transport material, a second layer 112-2 having a second hole transport material, a third layer 112-3 having a third hole transport material, and a fourth layer 113 having a host material and a light-emitting material. The HOMO level of the second hole transport material is deeper than the HOMO level of the first hole transport material, the HOMO level of the host material is deeper than the HOMO level of the second hole transport material, the HOMO level of the third hole transport material is the same as or deeper than the HOMO level of the host material, and the difference between the HOMO levels of the second hole transport material and the HOMO levels of the third hole transport material is 0.3 eV or less.

Description

[Technical Field]

[0001] One aspect of the present invention is a light-emitting element, a display module, a lighting module, a display device, This invention relates to optical devices, electronic devices, and lighting devices. One aspect of the present invention is not limited to the above-mentioned technical field. Not specified. The technical field of one aspect of the invention disclosed herein, etc., relates to a product, method, or manufacturing. This relates to a method. Alternatively, one aspect of the present invention relates to a process, machine, or manufacture. This relates to tea, or composition of matter. More specifically, the technical fields of one aspect of the present invention disclosed herein include semiconductor devices, and Display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, imaging devices, and their A driving method, or a method for manufacturing such a method, can be given as an example. [Background technology]

[0002] Electroluminescence (EL) using organic compounds The practical application of light-emitting elements (organic EL elements) that utilize ence is progressing. The basic structure consists of an organic compound layer (EL layer) containing a light-emitting material sandwiched between a pair of electrodes. Therefore, a voltage is applied to this element to inject carriers, and the recombination energy of those carriers is calculated. By using this method, it is possible to obtain light emission from light-emitting materials.

[0003] Because these light-emitting elements are self-emissive, when used as pixels in a display, they differ from liquid crystals in their properties. Flat panel displays offer advantages such as high visibility and the elimination of the need for a backlight. It is suitable as an element. Furthermore, a display using such a light-emitting element is thin and lightweight. Another great advantage is that it can be fabricated. Additionally, it is also characterized by a very fast response speed. There is also.

[0004] Moreover, since these light-emitting elements can form a light-emitting layer continuously in two dimensions, light emission can be obtained in a planar shape. This is a characteristic that is difficult to achieve with point light sources typified by incandescent bulbs and LEDs, or line light sources typified by fluorescent lamps. Therefore, it has high utility value as a planar light source that can be applied to lighting and the like. This is a characteristic that is difficult to obtain with point light sources typified by incandescent bulbs and LEDs, or line light sources typified by fluorescent lamps. Therefore, it has high utility value as a planar light source that can be applied to lighting and the like. This is a characteristic that is difficult to obtain with point light sources typified by incandescent bulbs and LEDs, or line light sources typified by fluorescent lamps. Therefore, it has high utility value as a planar light source that can be applied to lighting and the like. There is also high utility value.

[0005] Thus, displays and lighting devices using such light-emitting elements are very suitable for use in various electronic devices, and research and development are being advanced to obtain light-emitting elements with better efficiency and longer life. However, research and development are being advanced to obtain light-emitting elements with better efficiency and longer life.

[0006] As a material for a hole injection layer used to facilitate the injection of carriers, particularly holes, into the EL layer, there is an organic acceptor. Since the organic acceptor can be easily formed into a film by evaporation, it is suitable for mass production and its use is spreading. However, if the LUMO level of the organic acceptor and the HOMO level of the organic compound constituting the hole transport layer are far apart, it is difficult to inject holes into the EL layer. Therefore, if a material with a shallow HOMO level is used as the organic compound constituting the hole transport layer in order to bring the LUMO of the organic acceptor and the HOMO level of the organic compound constituting the hole transport layer closer, then the difference between the HOMO level of the host material used in the light-emitting layer and the HOMO level of the organic compound constituting the hole transport layer will become large. For this reason, even if holes can be injected into the EL layer, there is a problem that it becomes difficult to inject holes from the hole transport layer into the host material of the light-emitting layer. As a material for a hole injection layer used to facilitate the injection of carriers, particularly holes, into the EL layer, there is an organic acceptor. Since the organic acceptor can be easily formed into a film by evaporation, it is suitable for mass production and its use is spreading. However, if the LUMO level of the organic acceptor and the HOMO level of the organic compound constituting the hole transport layer are far apart, it is difficult to inject holes into the EL layer. Therefore, if a material with a shallow HOMO level is used as the organic compound constituting the hole transport layer in order to bring the LUMO of the organic acceptor and the HOMO level of the organic compound constituting the hole transport layer closer, then the difference between the HOMO level of the host material used in the light-emitting layer and the HOMO level of the organic compound constituting the hole transport layer will become large. For this reason, even if holes can be injected into the EL layer, there is a problem that it becomes difficult to inject holes from the hole transport layer into the host material of the light-emitting layer. Therefore, if a material with a shallow HOMO level is used as the organic compound constituting the hole transport layer in order to bring the LUMO of the organic acceptor and the HOMO level of the organic compound constituting the hole transport layer closer, then the difference between the HOMO level of the host material used in the light-emitting layer and the HOMO level of the organic compound constituting the hole transport layer will become large. For this reason, even if holes can be injected into the EL layer, there is a problem that it becomes difficult to inject holes from the hole transport layer into the host material of the light-emitting layer. For this reason, even if holes can be injected into the EL layer, there is a problem that it becomes difficult to inject holes from the hole transport layer into the host material of the light-emitting layer. For this reason, even if holes can be injected into the EL layer, there is a problem that it becomes difficult to inject holes from the hole transport layer into the host material of the light-emitting layer. There is a problem that it becomes difficult to inject holes from the hole transport layer into the host material of the light-emitting layer.

[0007] Patent Document 1 describes a first hole transport layer in contact with a hole injection layer and a light-emitting layer, with the first hole injection layer between them. Hole transport with a HOMO level between the HOMO level of the intrusion layer and the HOMO level of the host material. A configuration for providing materials is disclosed.

[0008] While the properties of light-emitting elements have improved remarkably, efficiency, durability, and all other characteristics remain challenging. It must be said that it is still insufficient to meet such advanced requirements. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] International Publication No. 2011 / 065136 Pamphlet [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, one aspect of the present invention aims to provide a novel light-emitting element. Or, life The objective is to provide a light-emitting element with good performance. Alternatively, to provide a light-emitting element with good luminous efficiency. It is intended for use in the public.

[0011] Alternatively, in another aspect of the present invention, a highly reliable light-emitting device, electronic device, and display device are provided, respectively. The purpose is to provide. Alternatively, in another aspect of the present invention, a light-emitting device with low power consumption. The purpose is to provide a device, electronic equipment, and display device, respectively.

[0012] The present invention only needs to solve one of the above-mentioned problems. [Means for solving the problem]

[0013] A light-emitting element according to one aspect of the present invention has a first electrode, a second electrode, and an EL layer, wherein the EL layer is Located between the first electrode and the second electrode, the EL layer consists of a hole injection layer, a first layer, and a second The hole injection layer has a third layer and a fourth layer, and the hole injection layer is between the first electrode and the first layer. The second layer is located between the first and third layers, and the fourth layer is located between the third and second layers. Located between the electrodes, the hole injection layer has an organic acceptor, and the first layer is the first hole transport The material has a second layer which has a second hole transport material and a third layer which has a third hole transport material. The fourth layer has a host material and a light-emitting material, and the HOMO level of the second hole transport material is The HOMO level of the host material is deeper than the HOMO level of the first hole transport material, and the HOMO level of the host material is deeper than the HOMO level of the second hole transport material. The HOMO level of the third hole transport material is deeper than the HOMO level of the host material. The HOMO level of the material is the same as or deeper than the HOMO level of the second hole transport material and the HOMO level of the third hole transport material. This is a light-emitting element in which the difference in HOMO levels of the feeding material is 0.3 eV or less.

[0014] A light-emitting element according to one aspect of the present invention has a first electrode, a second electrode, and an EL layer, wherein the EL layer is Located between the first electrode and the second electrode, the EL layer comprises a hole injection layer and a first hole transport layer. The structure comprises a second hole transport layer, a third hole transport layer, and a light-emitting layer, and the hole injection layer is made of organic acrylic acid. It has a septum, the first hole transport layer has a first hole transport material, and the second hole transport layer has a second The third hole transport layer has a hole transport material, and the light-emitting layer has a hole transport material. The system comprises a hole transport material and a light-emitting material, and the HOMO level of the second hole transport material is equal to that of the first hole transport material. The HOMO level of the host material is deeper than the HOMO level of the second hole transport material HOMO Deeper than the previous level, the HOMO level of the third hole transport material is the same as the HOMO level of the host material. or deep between the HOMO levels of the second hole transport material and the HOMO levels of the third hole transport material This is a light-emitting element whose difference is 0.3 eV or less.

[0015] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the organic acceptor is 2 ,3,6,7,10,11-Hexacyano-1,4,5,8,9,12-Hexazatri This is a phenylene-based light-emitting element.

[0016] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the first hole transport material This is a light-emitting element whose HOMO level is -5.4 eV or higher.

[0017] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the first hole transport material The difference between the HOMO level of the first material and the HOMO level of the second hole transport material is 0.3 eV or less. It is an element.

[0018] Another aspect of the present invention is a light-emitting element having the above configuration, wherein a second hole transport material The difference between the HOMO level of the material and the HOMO level of the third hole transport material is 0.2 eV or less. It is an element.

[0019] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the first hole transport material The difference between the HOMO level of the first material and the HOMO level of the second hole transport material is 0.2 eV or less. It is an element.

[0020] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the HOMO of the light-emitting material This is a light-emitting element whose energy level is higher than the HOMO level of the host material.

[0021] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the first hole transport material However, it is a light-emitting element that has a fluorenylamine skeleton.

[0022] Another aspect of the present invention is a light-emitting element having the above configuration, wherein a second hole transport material This is a light-emitting element that has a triphenylamine skeleton.

[0023] Another aspect of the present invention is a light-emitting element having the above configuration, wherein a third hole transport material This is a light-emitting element made of a substance that does not contain amines.

[0024] Another aspect of the present invention is a light-emitting element having the above configuration, wherein a third hole transport material This is a light-emitting element containing a carbazole skeleton.

[0025] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the carbazole skeleton is A light-emitting element with a phenylcarbazole skeleton.

[0026] Another aspect of the present invention is a light-emitting element having the above configuration, wherein a third hole transport material This is a light-emitting element containing a triphenylene skeleton.

[0027] Another aspect of the present invention is a light-emitting element having the above configuration, wherein a third hole transport material This is a light-emitting element containing a naphthalene skeleton.

[0028] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the host material is ant This is a light-emitting element containing a helical skeleton.

[0029] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the host material is diphosphate This is a light-emitting element containing a nilanthracene skeleton.

[0030] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the host material is a carbide This is a light-emitting element containing a zole skeleton.

[0031] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the carbazole skeleton is The light-emitting element has a benzocarbazole skeleton. Particularly preferred is a benzocarbazole skeleton. This is a light-emitting element with a benzocarbazole skeleton.

[0032] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the light-emitting material emits fluorescence. It is a light-emitting element, which is a physical substance.

[0033] Furthermore, in another aspect of the present invention, in a light-emitting element having the above configuration, the light-emitting material emits This is a light-emitting element that emits blue fluorescence.

[0034] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the light-emitting material is a condensation atom. This is a light-emitting element made from a fragrant diamine compound.

[0035] Another aspect of the present invention is a light-emitting element having the above configuration, wherein the light-emitting material is pyrene This is a light-emitting element made of a diamine compound.

[0036] Alternatively, another aspect of the present invention provides a light-emitting element having the above configuration, and a transistor, or It is a light-emitting device having a substrate.

[0037] Alternatively, another aspect of the present invention provides a light-emitting device having the above configuration, and a sensor, an operating button, and It is an electronic device having a speaker or microphone.

[0038] Alternatively, another aspect of the present invention is a lighting device having the above configuration and a housing. It is placed there.

[0039] In this specification, the term "light-emitting device" includes image display devices that use light-emitting elements. Furthermore, a connector can be attached to the light-emitting element, for example, an anisotropic conductive film or TCP (Tape Carrier). A module with an aftermarket package attached, and a printed circuit board beyond the TCP. The installed module or light-emitting element uses the COG (Chip On Glass) method. Modules on which ICs (integrated circuits) are directly mounted may have light-emitting devices. Furthermore, lighting fixtures and the like may have light-emitting devices. [Effects of the Invention]

[0040] In one aspect of the present invention, a novel light-emitting element can be provided, or a light-emitting element with a good lifespan can be provided. We can provide an element. Or, we can provide a light-emitting element with good luminescence efficiency. ru.

[0041] Alternatively, in another aspect of the present invention, a highly reliable light-emitting device, electronic device, and display device are provided, respectively. It can be provided. Or, in another aspect of the present invention, a light-emitting device with low power consumption, Electronic devices and display devices can be provided, respectively.

[0042] Furthermore, the description of these effects does not preclude the existence of other effects. The embodiment does not necessarily have to have all of these effects. Furthermore, other effects are... This will become clear from the description in the specification, drawings, claims, etc., and the specification, drawings Furthermore, it is possible to extract other effects from the descriptions in the claims and other documents. [Brief explanation of the drawing]

[0043] [Figure 1] Schematic diagram of a light-emitting element. [Figure 2] Conceptual diagram of an active matrix light-emitting device. [Figure 3] Conceptual diagram of an active matrix light-emitting device. [Figure 4] Conceptual diagram of an active matrix light-emitting device. [Figure 5] Conceptual diagram of a passive matrix type light-emitting device. [Figure 6] A diagram representing a lighting device. [Figure 7] A diagram representing electronic devices. [Figure 8] A diagram representing a light source device. [Figure 9] A diagram representing a lighting device. [Figure 10] A diagram representing a lighting device. [Figure 11] A diagram showing an in-vehicle display device and lighting system. [Figure 12] A diagram representing electronic devices. [Figure 13] A diagram representing electronic devices. [Figure 14] Brightness-current density characteristics of light-emitting element 1. [Figure 15] Current efficiency-luminance characteristics of light-emitting element 1. [Figure 16] Brightness-voltage characteristics of light-emitting element 1. [Figure 17] Current-voltage characteristics of light-emitting element 1. [Figure 18] External quantum efficiency-luminance characteristics of light-emitting element 1. [Figure 19] Emission spectrum of light-emitting element 1. [Figure 20] Normalized luminance-time variation characteristics of light-emitting element 1. [Figure 21] Brightness-current density characteristics of light-emitting element 2 and light-emitting element 3. [Figure 22] Current efficiency-luminance characteristics of light-emitting element 2 and light-emitting element 3. [Figure 23] Brightness-voltage characteristics of light-emitting element 2 and light-emitting element 3. [Figure 24] Current-voltage characteristics of light-emitting element 2 and light-emitting element 3. [Figure 25]External quantum efficiency-luminance characteristics of light-emitting element 2 and light-emitting element 3. [Figure 26] Emission spectra of light-emitting element 2 and light-emitting element 3. [Figure 27] Normalized luminance-time variation characteristics of light-emitting element 2 and light-emitting element 3. [Figure 28] Brightness-current density characteristics of light-emitting element 4. [Figure 29] Current efficiency-luminance characteristics of the light-emitting element 4. [Figure 30] Brightness-voltage characteristics of light-emitting element 4. [Figure 31] Current-voltage characteristics of light-emitting element 4. [Figure 32] External quantum efficiency-luminance characteristics of light-emitting element 4. [Figure 33] Emission spectrum of light-emitting element 4. [Figure 34] Normalized brightness-time variation characteristics of the light-emitting element 4. [Figure 35] Brightness-current density characteristics of the light-emitting element 5. [Figure 36] Current efficiency-luminance characteristics of the light-emitting element 5. [Figure 37] Brightness-voltage characteristics of light-emitting element 5. [Figure 38] Current-voltage characteristics of the light-emitting element 5. [Figure 39] External quantum efficiency-luminance characteristics of light-emitting element 5. [Figure 40] Emission spectrum of light-emitting element 5. [Figure 41] Normalized brightness-time variation characteristics of the light-emitting element 5. [Figure 42] Brightness-current density characteristics of light-emitting elements 6 to 8. [Figure 43] Current efficiency-luminance characteristics of light-emitting elements 6 to 8. [Figure 44] Brightness-voltage characteristics of light-emitting elements 6 to 8. [Figure 45] Current-voltage characteristics of light-emitting elements 6 to 8. [Figure 46] External quantum efficiency-luminance characteristics of light-emitting elements 6 to 8. [Figure 47] Emission spectra of light-emitting elements 6 to 8. [Figure 48] Normalized brightness-time variation characteristics of light-emitting elements 6 to 8. [Figure 49] Brightness-current density characteristics of light-emitting elements 9 to 11. [Figure 50] Current efficiency-luminance characteristics of light-emitting elements 9 to 11. [Figure 51] Brightness-voltage characteristics of light-emitting elements 9 to 11. [Figure 52] Current-voltage characteristics of light-emitting elements 9 to 11. [Figure 53] External quantum efficiency-luminance characteristics of light-emitting elements 9 to 11. [Figure 54] Emission spectra of light-emitting elements 9 to 11. [Figure 55] Normalized brightness-time variation characteristics of light-emitting elements 9 to 11. [Figure 56] Brightness-current density characteristics of the light-emitting element 12. [Figure 57] Current efficiency-luminance characteristics of the light-emitting element 12. [Figure 58] Brightness-voltage characteristics of the light-emitting element 12. [Figure 59] Current-voltage characteristics of the light-emitting element 12. [Figure 60] External quantum efficiency-luminance characteristics of the light-emitting element 12. [Figure 61] Emission spectrum of light-emitting element 12. [Figure 62] Normalized luminance-time variation characteristics of the light-emitting element 12. [Figure 63] 1H-NMR chart of BBAβNB. [Figure 64] 1H-NMR chart of βNP2PC. [Figure 65] 1H-NMR chart of BBAαNB. [Figure 66] 1H-NMR chart of BBAβNBi. [Figure 67] 1H-NMR chart of βNPβNC. [Modes for carrying out the invention]

[0044] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is as follows Not limited to the description, the form and details thereof may be described without departing from the spirit and scope of the present invention. Those skilled in the art will readily understand that the invention can be modified in various ways. Therefore, the present invention is as follows: This should not be interpreted as being limited to the contents described in the embodiments.

[0045] (Embodiment 1) Figure 1(A) is a diagram showing a light-emitting element according to one embodiment of the present invention. The light-emitting element according to one embodiment of the present invention is It has a first electrode 101, a second electrode 102, and an EL layer 103, and the EL layer 103 is the first electrode From pole 101 side: hole injection layer 111, first hole transport layer 112-1, second hole transport layer 11 2-2, it has a third hole transport layer 112-3 and an emissive layer 113. It also has an electron transport layer 114, It may also have an electron injection layer 115.

[0046] In one embodiment of the present invention, the light-emitting layer 113 includes a host material and a light-emitting material, and has holes The injection layer 111 contains an organic acceptor, the first hole transport layer 112-1, and the second hole transport layer 11 2-2 and the third hole transport layer 112-3 are the first hole transport material and the second hole transport material, respectively. It also includes a third hole transport material.

[0047] Furthermore, the HOMO level of the host material is deeper than the HOMO level of the second hole transport material. The HOMO level of the second hole transport material is located at the same position as the HOMO level of the first hole transport material. It is located at an even deeper position. Furthermore, the HOMO level of the third hole transport material is the H level of the host material. It is located at the same or deeper level as the OMO level. However, the HOMO level of the second hole transport material The difference between the HOMO level of the third hole transport material and the HOMO level of the third hole transport material shall be 0.3 eV or less.

[0048] The organic acceptor is an organic compound with a deep LUMO level. This causes charge separation between other organic compounds whose LUMO and HOMO levels are close. By doing so, holes can be generated in the organic compound. That is, in this implementation In this type of light-emitting device, holes are generated in the first hole transport material that is in contact with the organic acceptor. The acceptor is a compound having an electron-withdrawing group (halogen group or cyano group), for example, 7,7 8,8-Tetracyano-2,3,5,6-Tetrafluoroquinodimethane (abbreviation: F4-T CNQ), 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, Chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12- It is good to use hexaazatriphenylene (HAT-CN), etc. In particular, HAT-CN is It is preferable because it has high receptor properties and stable film structure.

[0049] The difference between the LUMO level of the organic acceptor and the HOMO level of the first hole transport material is the difference between the LUMO level of the organic acceptor and the HOMO level of the first hole transport material. It depends on the strength of the acceptability of the puta, so it's not particularly limited, but generally it's a difference in energy levels. If the voltage is around 1 eV or less, holes can be injected. HAT-CN is an organic acceptor. When used as such, the LUMO level of HAT-CN is obtained from cyclic voltammetry measurements. Since it is estimated to be -4.41eV, the HOMO level of the first hole transport material is -5.4e It is preferable that the HOMO level is V or higher. However, the HOMO level of the first hole transport material is not too high. If it becomes too much, then the hole injection into the second hole transport material will deteriorate. Also, the ITO Since the work function of the anode is around -5eV, the first positive anode has a higher HOMO level than that. Using hole transport materials is disadvantageous. Therefore, the HOMO level of the first hole transport material It is preferable that the voltage is -5.0 eV or less.

[0050] The holes generated in the first hole transport material move toward the second electrode 102 due to the electric field, It is injected into the second hole transport layer 112-2. The second hole transport layer 112-2 is composed of the second The HOMO level of the hole transport material is the HOMO level of the first hole transport material and the H level of the host material. Because it is located between the OMO levels, the second hole transport layer can easily be transported from the first hole transport layer 112-1. Holes can be injected into the transport layer 112-2. Note that the first hole transport material and the second hole The HOMO level difference of pore-transporting materials should be 0.3 eV or less to allow for smooth hole injection. It is preferable that the difference be 0.2 eV or less in order to facilitate hole injection. It is preferable to do so.

[0051] The holes injected into the second hole transport layer 112-2 are further transported by the electric field to the second electrode 102 It moves toward the third hole transport layer 112-3 and is injected into the third hole transport layer 112-3. The third hole transport material contained in has a HOMO level that is the same as the HOMO level of the host material. The difference between the HOMO level of the second hole transport material and the HOMO level of the second hole transport material is less than 0.35 eV (effective). It is a material with a single-digit number (0.3 eV or less). The HOMO level of the second hole transport material and the third Since the difference with the HOMO level of the hole transport material is 0.3 eV or less, the second hole transport layer 11 The injection of holes from 2-2 to the third hole transport layer 112-3 proceeds smoothly. To smoothly inject holes, the HOMO level of the third hole transport material and the second hole transport The difference between the HOMO level of the material being fed and the HOMO level is less than 0.25 eV (less than or equal to 0.2 eV with one significant figure). It is preferable to do so.

[0052] The HOMO level of the third hole transport material is the same as or deeper than the HOMO level of the host material, There is no hole injection barrier from the third hole transport layer 112-3 to the light-emitting layer 113. Furthermore, the third Since the HOMO level of the hole transport material is the same as or deeper than the HOMO level of the host material, Holes are not only more easily injected directly into the light-emitting material, but also more easily injected directly into the host material. If holes preferentially enter the light-emitting material, the propagation of holes within the light-emitting layer becomes extremely difficult, and the light-emitting region It becomes quite localized at the hole transport layer / light emission layer interface. As a result, it negatively affects the device's lifespan. However, as in one aspect of the present invention, holes are also introduced into the host material, and the holes are generated. Within the light layer, light is primarily conducted through the host, while also being moderately affected by the hole traps in the light-emitting material. Therefore, the light-emitting area can be appropriately widened, resulting in high efficiency and long lifespan. The term "spreading" means that while holes are transported to some extent within the light-emitting layer, they do not penetrate completely. This is the state. Furthermore, it is preferable that the host material has hole transport properties. Specifically, it is preferable that it has an anthracene skeleton or a carbazole skeleton. Also, the host Since the material preferably also possesses electron transport properties, an anthracene skeleton is particularly suitable. In other words, the host material has both an anthracene skeleton and a carbazole skeleton simultaneously. Preferred. Also, the carbazole skeleton is a benzocarbazole skeleton or a dibenzocarbazole skeleton. It is preferable that it be a zole. These structures have a HOMO of 0.1 compared to carbazole. Because the volt level increases by about eV, holes can easily enter (which widens the moderate emission area mentioned above). This is because it makes it easier to form a deposit. In this way, this third hole transport layer 112-3 Having this feature is one of the characteristics of the light-emitting element in one aspect of the present invention.

[0053] Here, if the HOMO level of the luminescent material is shallower than the HOMO level of the host material, the host material When holes are injected into the light-emitting layer from a hole transport material having a shallower HOMO level than the material, Holes are injected preferentially into the light-emitting material rather than the luminescent material. Light-emitting material with a shallow HOMO level. When holes are injected into the material, they become trapped. The holes are trapped, and the flow of holes... If this process is disrupted, it can lead to charge accumulation, accelerated degradation of the light-emitting layer due to concentration of recombination regions, and reduced light emission. This can lead to problems such as decreased efficiency.

[0054] On the other hand, as in the light-emitting element of this embodiment, it has a third hole transport layer 112-3, and its HOM In light-emitting devices where the O level is the same as or deeper than the HOMO level of the host material, holes First, the holes are preferentially injected into the host material rather than the light-emitting material. As a result, the flow of holes is obstructed. Without this, holes are appropriately trapped in the light-emitting material, and the recombination regions are also dispersed. This results in various benefits, such as improved reliability and increased luminous efficiency.

[0055] Next, we will describe the detailed structure and material examples of the light-emitting element described above. As described above, the optical element has multiple layers between the pair of electrodes, the first electrode 101 and the second electrode 102. It has an EL layer 103 made of the following, and the EL layer 103 is at least from the first electrode 101 side, Hole injection layer 111, first hole transport layer 112-1, second hole transport layer 112-2, third It includes a hole transport layer 112-3 and a light-emitting layer 113.

[0056] Other layers included in the EL layer 103 are not particularly limited, and include hole injection layers and hole transport layers. Various layer structures such as layers, electron injection layers, carrier blocking layers, exciton blocking layers, and charge generation layers. The construction method can be applied.

[0057] The first electrode 101 is made of a metal, alloy, or conductive material with a large work function (specifically, 4.0 eV or more). It is preferable to form them using chemical compounds and mixtures thereof. Specifically, for example, For example, indium tin oxide (ITO), silica Indium oxide-tin oxide and indium oxide-zinc oxide containing silicon dioxide or silicon dioxide. Examples include indium oxide (IWZO) containing tungsten oxide and zinc oxide. These conductive metal oxide films are usually deposited by sputtering, but sol-ge It is also acceptable to use methods such as the Lu method for fabrication. An example of a fabrication method is indium oxide-oxide Zinc is used in a target where 1-20 wt% zinc oxide is added to indium oxide. Methods include forming by the puttering method. Additionally, tungsten oxide and zinc oxide are used. The contained indium oxide (IWZO) has a ratio of 0.5% to tungsten oxide relative to indium oxide. Sputtering is performed using a target containing 5-5 wt% zinc oxide and 0.1-1 wt% zinc oxide. It can also be formed by law. Other materials include gold (Au), platinum (Pt), and nickel (Ni). , tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt ( Co), copper (Cu), palladium (Pd), or nitrides of metallic materials (e.g., titanium nitride) Examples include (n). Graphene can also be used. Note that the composite material described later is EL By using it in the layer that is in contact with the first electrode 101 in layer 103, regardless of the work function, It will become possible to select the polar materials.

[0058] Regarding the laminated structure of the EL layer 103, in this embodiment, as shown in Figure 1(A), holes Injection layer 111, first hole transport layer 112-1, second hole transport layer 112-2, third hole In addition to the transport layer 112-3 and the light-emitting layer 113, it also has an electron transport layer 114 and an electron injection layer 115. The configuration is as shown in Figure 1(B), with a hole injection layer 111, a first hole transport layer 112- 1. In addition to the second hole transport layer 112-2, the third hole transport layer 112-3, and the light-emitting layer 113 Two types of configurations, one having an electron transport layer 114, an electron injection layer 115, and a charge generation layer 116. Let's explain the composition. The materials that make up each layer are specifically described below.

[0059] The hole injection layer 111 is a layer containing an organic acceptor. The organic acceptor is an electron absorber. Compounds having drawing groups (halogen groups or cyano groups) can be used, such as 7,7,8,8-te Tracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), 3,6-Difluoro-2,5,7,7,8,8-Hexacyanoquinodimethane, Chloranil , 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaza Triphenylene (HAT-CN), etc., can be used as an organic acceptor. Compounds in which an electron-withdrawing group is bonded to a condensed aromatic ring containing multiple heteroatoms, such as AT-CN. However, it is thermally stable and preferable. The organic acceptor is adjacent to the hole transport layer (or hole Electrons can be extracted from the transport material by applying at least an electric field.

[0060] By forming the hole injection layer 111, the hole injection performance is improved, and the driving voltage is reduced. A light-emitting element can be obtained. In addition, organic acceptors are easy to deposit and easy to form films. Therefore, it is an easy-to-use material.

[0061] The hole transport layer consists of a first hole transport layer 112-1, a second hole transport layer 112-2, and a third hole transport layer It consists of pore transport layers 112-3. The first hole transport layer 112-1 to the third hole transport layer Each of the transport layers contains a hole transport material that has hole transport properties, and the first hole transport layer 112 -1 contains the first hole transport material, and the second hole transport layer 112-2 contains the second hole transport material. The third hole transport layer 112-3 contains a third hole transport material. So, 1 x 10 -6 cm 2 It is preferable that the hole mobility is greater than or equal to / Vs. Between each material, the HOMO level of the second hole transport material is the HOMO level of the first hole transport material. Deeper than the O level, the HOMO level of the host material contained in the luminescent layer 113 is a second hole transport. The HOMO level of the third hole transport material is deeper than the HOMO level of the host material. The MO level is the same as or deeper than the HOMO level of the second hole transport material and the third hole transport material. A relationship exists where the difference in HOMO levels is less than 0.3 eV. Furthermore, the second hole transport material... The difference between the HOMO level and the HOMO level of the third hole transport material should preferably be 0.2 eV or less. It seems so.

[0062] For the first hole transport material, it is preferable to use a hole transport material with a relatively shallow HOMO level. Indeed, such organic compounds include triarylamines and fluorenyl Substances having an amine skeleton are preferred.

[0063] For the third hole transport material, it is preferable to use a hole transport material with a relatively deep HOMO level. It seems so. Organic compounds containing amines tend to have shallow HOMO levels, so amines A hole transport material that does not perform hole transport is preferred. A suitable hole transport material is carbazole. A hole transport material containing a skeleton is preferred. Suitable use of organic compounds, such as those containing a carbazole skeleton and a naphthalene skeleton. It is possible.

[0064] The second hole transport material is the HOMO between the first hole transport material and the third hole transport material. A hole transport material having energy levels is preferred. Specifically, it is a triarylamine and A hole transport material containing a triphenylamine skeleton is preferred. It is preferable that the phenyl groups in the skeleton are not fused rings.

[0065] The light-emitting layer 113 is a layer containing a host material and a light-emitting material. The light-emitting material is a fluorescent substance. Even if it is a phosphorescent material, or a material that exhibits thermally activated delayed fluorescence (TADF) Either is fine. Also, even if it is a single layer, it can consist of multiple layers containing different light-emitting materials. It is also acceptable if it is. In one aspect of the present invention, the light-emitting layer 113 is a layer that exhibits fluorescence, particularly This method can be more preferably applied when the layer exhibits blue fluorescence emission.

[0066] In the light-emitting layer 113, possible materials that can be used as fluorescent light-emitting materials include, for example, Examples include those listed below. Other fluorescent materials can also be used.

[0067] 5,6-Bis[4-(10-phenyl-9-antryl)phenyl]-2,2'-bipyri Zin (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl-9-antri [Lu)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2BPy), N, N'-Bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-N,N' -Diphenyl-pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N'- Bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H-fluorene] -9-yl)phenyl]-pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAP) rn), N,N'-bis[4-(9H-carbazol-9-yl)phenyl]-N,N' -Diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4-(9H-Cal Bazole-9-yl)-4'-(10-phenyl-9-anthryl)triphenylamine (Abbreviation: YGAPA), 4-(9H-carbazole-9-yl)-4'-(9,10-di Phenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-di Phenyl-N-[4-(10-phenyl-9-antryl)phenyl]-9H-carbazo 3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra-ter t-butylperylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4' -(9-phenyl-9H-carbazole-3-yl)triphenylamine (abbreviation: PCB) APA), N,N''-(2-tert-butylanthracene-9,10-diyldi-4) ,1-phenylene)bis[N,N',N'-triphenyl-1,4-phenylenediamine ] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl- 2-Anthryl)phenyl]-9H-carbazole-3-amine (abbreviation: 2PCAPPA) ), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N',N' -Triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N,N,N' ,N',N'',N'',N''',N'''-Octaphenyldibenzo[g,p]cri Sen-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N-(9 ,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazole-3 -amine (abbreviation: 2PCAPA), N-[9,10-bis(1,1'-biphenyl-2- [Iyl)-2-anthryl]-N,9-diphenyl-9H-carbazole-3-amine (abbreviated) Name: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N', N'-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9, 10-Bis(1,1'-biphenyl-2-yl)-2-anthryl]-N,N',N'- Triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bi Su(1,1'-biphenyl-2-yl)-N-[4-(9H-carbazole-9-yl) Phenyl]-N-phenylanthracene-2-amine (abbreviation: 2YGABPhA), N, N,9-Triphenylanthracene-9-amine (abbreviation: DPhAPhA) Coumarin 54 5T, N,N'-diphenylquinacridone, (abbreviation: DPQd), rubrene, 5,12- Bis(1,1'-biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: B) PT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl -4H-pyran-4-ylidene)propanedinitrile (abbreviation: DCM1), 2-{2-Me Chill-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinori [Zin-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation) :DCM2), N,N,N',N'-Tetrakis(4-methylphenyl)tetracene-5 ,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N '-Tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluorantene-3, 10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1 ,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[i j]Quinoridine-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinite Lil (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7 -Tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolidi [-9-yl)ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis{2-[4-(dimethylamino)phenyl]ethenyl }-4H-pyran-4-ylidene)propanedinitrile (abbreviation: BisDCM), 2-{ 2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7- Tetrahydro-1H,5H-benzo[ij]quinoridine-9-yl)ethenyl]-4H- Examples include pyran-4-ylidene propanedinitrile (abbreviation: BisDCJTM). In particular, pyrethroids such as 1,6FLPAPrn and 1,6mMemFLPAPrn Condensed aromatic diamine compounds, such as those represented by ¹¹ compounds, have high hole-trapping properties and high luminescence efficiency. It is preferable because it is highly reliable.

[0068] Examples of materials that can be used as phosphorescent materials in the light-emitting layer 113 include, for example, The following are some examples.

[0069] Tris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H -1,2,4-triazole-3-yl-κN2]phenyl-κC}iridium(III ) (abbreviation: [Ir(mpptz-dmp)3]), Tris(5-methyl-3,4-diphen) Iridium(III) (abbreviation: [Ir(Mpt) z)3]), Tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H -1,2,4-Triazolat] Iridium(III) (Abbreviation: [Ir(iPrptz-3 Organometallic iridium complexes having a 4H-triazole skeleton, such as b)3]), and Tris [3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-tria Zolato] Iridium (III) (abbreviation: [Ir(Mptz1-mp)3]), Tris (1 -Methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium (III) (Abbreviation: [Ir(Prptz1-Me)3]) 1H-triazole bone iridium organometallic complexes with a specific classification, and fac-tris[(1-2,6-diisopropyl [Phenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir (iPrpmi)3]), Tris[3-(2,6-dimethylphenyl)-7-methylimi Dazo[1,2-f]phenantriginato]iridium(III) (abbreviation:[Ir(dmp Organometallic iridium complexes having an imidazole skeleton such as impt-Me)3]), Bis[2-(4',6'-difluorophenyl)pyridinate-N,C 2’ ]iridium( III) Tetrakis(1-pyrazolyl)borate (abbreviation: Fir6), bis[2-(4' ,6'-Difluorophenyl)pyridinate-N,C 2’ Iridium(III) picolina Firpic (abbreviation: Firpic), bis{2-[3',5'-bis(trifluoromethyl) [enyl]pyridinate-N,C 2’ Iridium(III) picolinate (abbreviation: [Ir( CF3ppy)2(pic)]), bis[2-(4',6'-difluorophenyl)pyri Dinato-N,C 2’ Iridium(III) acetylacetonate (abbreviation: FIraca) organometallic iridium ligands having electron-withdrawing groups as shown in c) Examples include um complexes. These are compounds that exhibit blue phosphorescence, starting from 440 nm. This compound has an emission peak at 520 nm.

[0070] Also, tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), Tris(4-t-butyl-6-phenylpyrimidinato)yli Dium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis (6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mp) pm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4- Phenylpyrimidina) Iridium(III) (Abbreviation: [Ir(tBuppm)2(ac (ac)), (acetylacetonate)bis[6-(2-norbornyl)-4-phenylp Limiginato Iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (Acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenyl pyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)] ), (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(II I) (abbreviation: [Ir(dppm)2(acac)]) and other organometallic iridium complexes having a pyrimidine skeleton, and (acetylacetonato)bis(3,5-dimethyl-2-phenyl pyridazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac) ), (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyr idazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]) and other organometallic iridium complexes having a pyrazine skeleton, and tris(2-phenylpyrid inato-N,C )iridium(III) (abbreviation: [Ir(ppy)3]), bis(2- 2’ phenylpyridinato-N,C )iridium(III) acetylacetonate (abbreviation: 2’ [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(I II) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(be nzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris (2-phenylquinolinato-N,C )iridium(III) (abbreviation: [Ir(pq) 2’ 3]), bis(2-phenylquinolinato-N,C )iridium(III) acetylacet 2’ )ate (abbreviation: [Ir(pq)2(acac)]) and other organometallic iridium complexes having a pyridine skeleton, and tris(acetylacetonato)(monophenanthroline)te​​​​ Rare earth metals such as rubium(III) (abbreviation: [Tb(acac)3(Phen)]) Examples include complexes. These are compounds that mainly exhibit green phosphorescence, with a wavelength of 500 nm to 6 It has an emission peak at 00 nm. Furthermore, it is an organometallic iridium complex with a pyrimidine skeleton. The body is particularly preferable because it is outstanding in terms of reliability and luminescence efficiency.

[0071] Also, (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimid Sodium iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis(Ir(5mdppm)2(dibm)]), [4,6-Bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridi Um(III) (abbreviation: [Ir(5mdppm)2(dpm)]), bis[4,6-di( Naphthalene-1-yl)pyrimidinato](dipivaloylmethanato)iridium(III) Organometallic gold with a pyrimidine skeleton, such as (abbreviation: [Ir(d1npm)2(dpm)]) Iridium complexes of the genus, and (acetylacetonato)bis(2,3,5-triphenylpyrazine Iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2, 3,5-Triphenylpyrazinate)(dipivaloylmethanato) Iridium(III) (abbreviated) Name: [Ir(tppr)2(dpm)]), (acetylacetonato)bis[2,3-bi [Ir(4-fluorophenyl)quinoxalinato] Iridium(III) (abbreviation: [Ir(F Organometallic iridium complexes having a pyrazine skeleton such as dpq)2(acac)]), Tris(1-phenylisoquinolinato-N,C) 2’ ) Iridium(III) (abbreviation: [I r(piq)3]), bis(1-phenylisoquinolinato-N,C 2’ ) Iridium (I II) Pyrrhizic acid like acetylacetonate (abbreviation: [Ir(piq)2(acac)]) In addition to organometallic iridium complexes with a din skeleton, 2, 3, 7, 8, 12, 13, 17, 1 8-Octaethyl-21H,23H-Porphyrin Platinum(II) (abbreviation: PtOEP) Platinum complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monof Phenanthroline Europium(III) (Abbreviation: [Eu(DBM)3(Phen)]) Tris[1-(2-tenoyl)-3,3,3-trifluoroacetonate](monofena (Eu(TTA)3(Phen)) Examples include rare earth metal complexes. These are compounds that exhibit red phosphorescence, and 6 It has an emission peak from 00 nm to 700 nm. It is also an organometallic compound with a pyrazine skeleton. Iridium complexes produce a red emission with good chromaticity.

[0072] In addition to the phosphorescent compounds described above, known phosphorescent materials may also be selected and used. stomach.

[0073] TADF materials include fullerenes and their derivatives, and acridine derivatives such as proflavin. Eosin and other substances can be used. Also, magnesium (Mg), zinc (Zn), and cadmium can be used. Cd, tin (Sn), platinum (Pt), indium (In), or palladium ( Metal-containing porphyrins including Pd, etc. Examples of such metal-containing porphyrins are as follows: The protoporphyrin-tin fluoride complex (SnF2(Proto IX) is shown in the structural formula. )), Mesoporphyrin-tin fluoride complex (SnF2(Meso IX)), Hematopor Firin-tin fluoride complex (SnF2(Hemato IX)), coproporphyrinte Tramethyl ester-tin fluoride complex (SnF2(Copro III-4Me)), Ethoethylporphyrin-tin fluoride complex (SnF2(OEP)), Ethioporphyrin -Tin fluoride complex (SnF2(Etio I)), octaethylporphyrin-platinum chloride Examples include complexes (PtCl2OEP), etc.

[0074] [ka]

[0075] Furthermore, the following structural formula shows 2-biphenyl-4,6-bis(12-phenylindrol [2,3-a]carbazole-11-yl)-1,3,5-triazine (abbreviation: PIC- TRZ) and 9-(4,6-diphenyl-1,3,5-triazine-2-yl)-9'- Phenyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzTzn), 9-[ 4-(4,6-diphenyl-1,3,5-triazine-2-yl)phenyl]-9'-f Enyl-9H,9'H-3,3'-bicarbazole (abbreviation: PCCzPTzn), 2-[ 4-(10H-phenoxazine-10-yl)phenyl]-4,6-diphenyl-1,3 ,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-di Hydrophenazine-10-yl)phenyl]-4,5-diphenyl-1,2,4-tri Zol (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acrylidine-10 -Il)-9H-Xanthen-9-On (abbreviation: ACRXTN), Bis[4-(9,9- Dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DP) S), 10-phenyl-10H,10'H-spiro[acridine-9,9'-anthrace π-electron-rich heteroaromatic rings such as [n]-10'-one (abbreviated as ACRSA) and π-electron-deficient heteroaromatic rings Heterocyclic compounds having both heteroaromatic rings can also be used. These heterocyclic compounds have π-electric components. Because it has electron-excess heteroaromatic rings and π-electron-deficient heteroaromatic rings, it exhibits electron transport and hole transport properties. Both properties are high and desirable. Furthermore, the π-electron-rich heteroaromatic ring and the π-electron-deficient heteroaromatic ring are The directly bonded substance has the characteristics of a donor of a π-electron-rich heteroaromatic ring and an a of a π-electron-deficient heteroaromatic ring. Both the S1 and T1 levels become stronger, and the energy difference between them decreases, thus reducing thermal activity. This is particularly preferable because it efficiently yields delayed-activation fluorescence. Alternatively, an aromatic ring to which an electron-withdrawing group such as a cyano group is attached may be used.

[0076] [ka]

[0077] The host material for the light-emitting layer can be various materials such as electron-transporting materials or hole-transporting materials. Various carrier transport materials can be used.

[0078] Examples of materials with hole transport properties include 4,4'-bis[N-(1-naphthyl)-N-pheny [Nuamino]biphenyl (abbreviation: NPB), N,N'-bis(3-methylphenyl)-N, N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4'-bis[N-(spiro-9,9'-bifluoren-2-yl)-N-phenyl Mino-biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluorene -9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9- Phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4-F Phenyl-4'-(9-phenyl-9H-carbazole-3-yl)triphenylamine ( Abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9-H- Luvazole-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-na Phthyl)-4'-(9-phenyl-9H-carbazole-3-yl)-triphenylamine n (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl- 9H-carbazole-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9- Dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl) Phenyl]-fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4- (9-phenyl-9H-carbazole-3-yl)phenyl]-spiro-9,9'-bif Compounds having an aromatic amine skeleton such as ruolen-2-amine (abbreviated as PCBASF) , 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)benzene Luvazolyl biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl) )-9-phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9 Compounds having a carbazole skeleton, such as H-carbazole (abbreviated as PCCP), and 4, 4',4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation) :DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorine [Len-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4- [4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibene Compounds containing a thiophene skeleton, such as zothiophene (abbreviation: DBTFLP-IV), and 4 ,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl) furans such as phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II) Examples include compounds having a skeleton. Among those mentioned above, compounds having an aromatic amine skeleton and Compounds with a carbazole skeleton are reliable and have high hole transport properties. This is preferable because it also contributes to reducing dynamic voltage.

[0079] Examples of materials with electron transport properties include bis(10-hydroxybenzo[h]quinoli Sodium beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolate) )(4-phenylphenolate)aluminum(III) (abbreviation: BAlq), bis(8- Zinc(II) (abbreviation: Znq), bis[2-(2-benzoxazolyl) [Phenolate]zinc(II) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl) Metal complexes such as phenolate zinc(II) (abbreviation: ZnBTZ) and 2-(4-biphenyl Ryl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation) :PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butyl) Enyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-te rt-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazole-2-yl) Phenyl]-9H-carbazole (abbreviation: CO11), 2,2’,2’’-(1,3,5 -benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TP BI), 2-[3-(Dibenzothiophen-4-yl)phenyl]-1-phenyl-1H -benzimidazole (abbreviation: mDBTBIm-II), etc., heterocyclic compounds having a polyazole skeleton, and 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzof ,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3’-(dibenzothio phen-4-yl)biphenyl-3-yl]dibenzof[h]quinoxaline (abbreviation: 2 mDBTBPDBq-II), 2-[3’-(9H-carbazol-9-yl)bipheny l-3-yl]dibenzof[h]quinoxaline (abbreviation: 2mCzBPDBq), 4,6 -bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPn P2Pm), 4,6-bis〔3-(4-dibenzothienyl)phenyl〕pyrimidine (abbreviation : 4,6mDBTP2Pm-II), etc., heterocyclic compounds having a diazine skeleton, and 3,5 -bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCz PPy), 1,3,5-tri[3-(3-pyridyl)-phenyl]benzene (abbreviation: Tm PyPB), etc., heterocyclic compounds having a pyridine skeleton. Among the above, heterocyclic compounds having a dia zine skeleton and heterocyclic compounds having a pyridine skeleton have good reliability and are preferable. In particular, heterocyclic compounds having a diazine (pyrimidine or pyrazine) skeleton have high electron transportability and contribute to reducing the driving voltage.

[0080] When using fluorescent materials as light-emitting materials, the host material should have an anthracene skeleton. Materials that are suitable for this purpose are used as host materials for fluorescent materials. When used in this way, it is possible to realize a light-emitting layer with good luminous efficiency and durability. Since many materials having a sen skeleton have deep HOMO levels, one aspect of the present invention is suitably applied. It is possible. As for materials having an anthracene skeleton to be used as a host material, A substance having a phenylanthracene skeleton, particularly a 9,10-diphenylanthracene skeleton It is preferable because it is chemically stable. Also, if the host material has a carbazole skeleton, This is preferable because it improves hole injection and transport, but the benzene ring is further condensed on the carbazole. When it contains a benzocarbazole skeleton, the HOMO is about 0.1 eV higher than that of carbazole. This is preferable because it makes it easier for holes to enter. In particular, if the host material is dibenzocarbazo When a carbazole skeleton is present, the HOMO becomes about 0.1 eV higher than that of carbazole, and holes are introduced. It is preferable because it becomes easier to transport holes, has excellent hole transport properties, and has high heat resistance. Furthermore, preferred host materials include a 9,10-diphenylanthracene skeleton and The carbazole skeleton (or benzocarbazole skeleton or dibenzocarbazole skeleton) It is a substance that sometimes possesses this property. Furthermore, from the viewpoint of the hole injection and transport properties mentioned above, the carbazole skeleton is Alternatively, a benzofluorene skeleton or a dibenzofluorene skeleton may be used. An example of quality is 9-phenyl-3-[4-(10-phenyl-9-antryl)phenyl [Lu]-9H-carbazole (abbreviation: PCzPA), 3-[4-(1-naphthyl)-pheny [L]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9-[4-(10-phenyl] [nyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7- [4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]cal Bazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-ant) [Lyl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA) ), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-bif Examples include phenyl-4'-yl}-anthracene (abbreviated as FLPPA). In particular, Cz PA, cgDBCzPA, 2mBnfPPA, and PCzPA exhibit very good characteristics. That is a favorable choice.

[0081] Furthermore, one embodiment of the present invention is particularly applicable to a light-emitting element that exhibits blue fluorescence. This is preferable.

[0082] Furthermore, the host material may be a mixture of multiple substances, and the mixed host material When used, a mixture of electron-transporting material and hole-transporting material is used. Preferably, by mixing an electron-transporting material with a hole-transporting material. Furthermore, the transport properties of the light-emitting layer 113 can be easily adjusted, and the recombination region can be easily controlled. This is possible. The ratio of the content of hole-transporting material to electron-transporting material is the ratio of hole-transporting material content. The ratio of electron-transporting material to electron-transporting material should be 1:9 to 9:1.

[0083] Furthermore, these mixed materials may form excited complexes. These excited complexes are luminescent materials. It forms an excited complex that emits light that overlaps with the wavelength of the lowest energy absorption band. By selecting such a combination, energy transfer becomes smooth, and favorable light emission can be efficiently obtained. Also, since the driving voltage is reduced, it is favorable. Further, since the driving voltage also decreases, it is favorable.

[0084] The electron transport layer 114 is a layer containing a substance having electron transporting properties, and as the substance having electron transporting properties, those exemplified as the substance that can be used for the host material can be used.

[0085] Between the electron transport layer 114 and the second electrode 102, as the electron injection layer 115, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), etc. such as alkali metals or alkaline earth metals or their compounds may be provided. An alkali metal or an alkaline earth metal or their compounds may be contained in a layer made of a substance having electron transporting properties, or an electride may be used. Examples of electrides include substances in which electrons are added at a high concentration to a mixed oxide of calcium and aluminum.

[0086] Also, instead of the electron injection layer 115, a charge generation layer 116 may be provided (FIG. 1(B)). The charge generation layer 116 is a layer that can inject holes into the layer adjacent to the cathode side of the layer and electrons into the layer adjacent to the anode side by applying a potential. The charge generation layer 116 contains at least a P-type layer 117. The P-type layer 117 is preferably formed using the composite material exemplified as the material that can constitute the above-described hole injection layer 111. Also, the P-type layer 117 may be formed by laminating a film containing the acceptor material described above as the material constituting the composite material and a film containing a hole transport material. By applying a potential to the P-type layer 117, electrons ​​​​​​​​​​Electrons are injected into the transport layer 114, and holes are injected into the second electrode 102, which is the cathode, and the light-emitting element operates. do.

[0087] In addition to the P-type layer 117, the charge generation layer 116 also includes an electron relay layer 118 and an electron injection buffer. It is preferable that one or both of the layers 119 are provided.

[0088] The electron relay layer 118 contains at least an electron-transporting material, and the electron injection buffer layer 1 It has the function of preventing interaction between 19 and the P-type layer 117, thereby enabling smooth electron transfer. The LUMO level of the electron-transporting material contained in the relay layer 118 is in the P-type layer 117. The LUMO level of the acceptor material and the charge generation layer 116 in the electron transport layer 114 It is preferable that the LUMO level is between the LUMO level of the material contained in the contacting layer. Electron relay layer 11 Specific energy levels of the LUMO level in electron-transporting materials used in 8 The voltage should be -5.0 eV or higher, preferably -5.0 eV to -3.0 eV. As for electron-transporting materials used in the electron relay layer 118, phthalocyanine-based materials are used. It is preferable to use a material or a metal complex having a metal-oxygen bond and an aromatic ligand.

[0089] The electron injection buffer layer 119 contains alkali metals, alkaline earth metals, rare earth metals, and These compounds (alkali metal compounds (oxides such as lithium oxide, halides, and carbonates) (including carbonates such as thium and cesium carbonate), alkaline earth metal compounds (oxides, halogens) Compounds of rare earth metals (including oxides, halides, and carbonates), or compounds of rare earth metals (including oxides, halides, and carbonates) It is possible to use materials with high electron injection capabilities, such as (m)).

[0090] Furthermore, the electron injection buffer layer 119 contains an electron transporting substance and a donor substance, and If performed, alkali metals, alkaline earth metals, and rare earth metals will be used as donor substances. , and these compounds (alkali metal compounds (oxides and halides such as lithium oxide) , including carbonates such as lithium carbonate and cesium carbonate), alkaline earth metal compounds (oxides, (including halides and carbonates), or compounds of rare earth metals (oxides, halides, carbon In addition to salts, tetratianaphthacene (abbreviated as TTN), nickerosene, decametine Organic compounds such as runicerosene can also be used. Therefore, it is formed using the same material as the material that constitutes the electron transport layer 114 described earlier. It is possible.

[0091] The material forming the second electrode 102 has a small work function (specifically, 3.8 eV or less). (Below) Metals, alloys, electrically conductive compounds, and mixtures thereof can be used. Specific examples of such cathode materials include alkaline materials such as lithium (Li) and cesium (Cs). Metallic compounds, as well as magnesium (Mg), calcium (Ca), strontium (Sr), etc. Elements belonging to Group 1 or Group 2 of the periodic table, and alloys containing these elements (MgAg, Rare earth metals such as AlLi, europium (Eu), ytterbium (Yb), and this Examples include alloys containing these. However, between the second electrode 102 and the electron transport layer, By providing an electron injection layer, regardless of the magnitude of the work function, Al, Ag, ITO, and silica can be used. Various conductive materials such as indium oxide-tin oxide containing silicon dioxide or silicon dioxide are used as the second... It can be used as electrode 102. These conductive materials are produced using dry methods such as vacuum deposition and sputtering, as well as inkjet methods. It is possible to deposit films using methods such as spin coating. Furthermore, wet deposition can be performed using the sol-gel method. It may be formed by a mold, or by a wet process using a paste of a metallic material.

[0092] Furthermore, various methods can be used to form the EL layer 103, regardless of whether they are dry or wet methods. This can be done using methods such as vacuum deposition, gravure printing, offset printing, and screen printing. You may use methods such as printing, inkjet printing, or spin coating.

[0093] Furthermore, each electrode or layer described above may be formed using different film deposition methods.

[0094] The configuration of the layer provided between the first electrode 101 and the second electrode 102 is as described above. It is not limited to this. However, if the light-emitting region and the metal used in the electrodes or carrier injection layer are in close proximity To suppress the quenching that occurs as a result, the first electrode 101 and the second electrode 1 A configuration is preferred in which a light-emitting region is provided at a location away from O2 where holes and electrons recombine.

[0095] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 113, and especially the recombination in the light-emitting layer 113, The carrier transport layer near the region suppresses energy transfer from excitons generated in the light-emitting layer. Therefore, the band gap is the light-emitting material that makes up the light-emitting layer or the light contained in the light-emitting layer. It is preferable to use materials with a band gap larger than the band gap of the material itself. It seems so.

[0096] Next, a light-emitting element with a configuration in which multiple light-emitting units are stacked (stacked element, tandem element and The embodiment of (also known as) will be explained with reference to Figure 1(C). This light-emitting element has an anode and a cathode Between them is a light-emitting element having multiple light-emitting units. One light-emitting unit is shown in Figure 1( It has a configuration almost identical to the EL layer 103 shown in A). In other words, the light-emitting element shown in Figure 1(C) The child is a light-emitting element having multiple light-emitting units, as shown in Figure 1(A) or Figure 1(B). An optical element can be described as a light-emitting element having one light-emitting unit.

[0097] In Figure 1(C), a first light-emitting unit is placed between the first electrode 501 and the second electrode 502. The first light-emitting unit 511 and the second light-emitting unit 512 are stacked, and the first light-emitting unit 511 and A charge generation layer 513 is provided between the first electrode 5 and the second light-emitting unit 512. 01 and the second electrode 502 correspond to the first electrode 101 and the second electrode 1 in Figure 1(A), respectively. This corresponds to 02, and the same thing described in the explanation of Figure 1(A) can be applied. Even though the first light-emitting unit 511 and the second light-emitting unit 512 have the same configuration, they have different configurations. It may be possible.

[0098] When a voltage is applied to the first electrode 501 and the second electrode 502, the charge generation layer 513 generates a charge. It has the function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit. In other words, in Figure 1(C), the potential of the first electrode is higher than the potential of the second electrode. When a voltage is applied in this manner, the charge generation layer 513 generates electrons in the first light-emitting unit 511. Any method that injects a hole into the second light-emitting unit 512 is acceptable.

[0099] The charge generation layer 513 is formed with the same configuration as the charge generation layer 116 described in Figure 1(B). Preferably, composite materials of organic compounds and metal oxides have good carrier implantation and carrier transport properties. Due to its superior performance, it can achieve low-voltage and low-current operation. If the anode side of the net is in contact with the charge generation layer 513, the charge generation layer 513 will light up the unit. Since it can also serve as the hole injection layer of the net, the light-emitting unit does not require a hole injection layer. That's fine.

[0100] Furthermore, if an electron injection buffer layer 119 is provided, the electron injection buffer layer 119 is on the anode side. In order to play the role of an electron injection layer in the light-emitting unit, the anode side of the light-emitting unit must always There is no need to form an electron injection layer.

[0101] Figure 1(C) illustrates a light-emitting element having two light-emitting units, but there are three or more This method can also be applied to light-emitting devices formed by stacking light-emitting units. Like a light-emitting element in the form of a charge generation layer 513, multiple light-emitting units are placed between a pair of electrodes. By partitioning and arranging the elements, high-brightness light emission is possible while maintaining a low current density, and further This enables the creation of long-life elements. Furthermore, it allows for low-voltage operation and enables the realization of light-emitting devices with low power consumption. It is possible.

[0102] Furthermore, by making the light-emitting color of each light-emitting unit different, the entire light-emitting element... This allows you to obtain light emission of a desired color. For example, a light-emitting element having two light-emitting units In this configuration, the first light-emitting unit produces red and green light, and the second light-emitting unit produces blue light. This makes it possible to obtain a light-emitting element that emits white light as a whole.

[0103] The above configuration may be combined with other embodiments or other configurations within this embodiment as appropriate. This is possible.

[0104] (Embodiment 2) This embodiment describes a light-emitting device using the light-emitting element described in Embodiment 1.

[0105] In this embodiment, regarding the light-emitting device made using the light-emitting element described in Embodiment 1: Let's explain using Figure 2. Figure 2(A) is a top view showing the light-emitting device, and Figure 2(B) is a top view of Figure 2. This is a cross-sectional view obtained by cutting (A) at AB and CD. This light-emitting device emits light from a light-emitting element. Controlling these are the drive circuit section (source line drive circuit) 601, indicated by the dotted line, and the pixel section. 602 includes a drive circuit section (gate line drive circuit) 603. Also, 604 is a sealing substrate. 605 is a sealing material, and the area enclosed by the sealing material 605 is a space 607. .

[0106] The routing wire 608 is input to the source line drive circuit 601 and the gate line drive circuit 603. FPC (Flexible Printed Circuit) is a wiring system for transmitting signals and serves as an external input terminal. (Input circuit) 609 receives video signals, clock signals, start signals, reset signals, etc. Receive. Note that only the FPC is shown in the diagram here, but this FPC has a print distribution A wire substrate (PWB) may be attached. The light-emitting device in this specification is a light-emitting device This includes not only the main unit but also the state in which the FPC or PWB is attached to it. ru.

[0107] Next, the cross-sectional structure will be explained using Figure 2(B). The drive circuit section is located on the element substrate 610. And a pixel section is formed, but here, the source line drive circuit 601 which is the drive circuit section and One pixel in the pixel section 602 is shown.

[0108] The element substrate 610 is a substrate made of glass, quartz, organic resin, metal, alloy, semiconductor, etc. FRP (Fiber Reinforced Plastics), PVF (Polyvinyl Fiber) It is made using a plastic substrate made of fluoride, polyester, or acrylic. That's all you need to do.

[0109] The structure of transistors used in pixels and driving circuits is not particularly limited. For example, inverse staggered It can be a type of transistor or a staggered transistor. Also, top Either a gate-type transistor or a bottom-gate transistor is acceptable. The semiconductor material is not particularly limited, and examples include silicon, germanium, silicon carbide, nitride Gallium can be used, or an In-Ga-Zn metal oxide can be used. An oxide semiconductor containing at least one of the elements, such as zinc, gallium, and zinc, may also be used.

[0110] The crystallinity of semiconductor materials used in transistors is not particularly limited; amorphous semiconductors, Crystalline semiconductors (microcrystalline semiconductors, polycrystalline semiconductors, single-crystal semiconductors, or semiconductors with a crystalline region in part) Any semiconductor having the properties of [the semiconductor material] may be used. If a semiconductor having crystalline properties is used, transients may occur. This is preferable because it suppresses the deterioration of the stanic characteristics.

[0111] Here, in addition to the transistors provided in the pixels and driving circuits mentioned above, the touch sensors and the like described later are also included. It is preferable to use oxide semiconductors for semiconductor devices such as transistors. It is particularly preferable to use oxide semiconductors with a wider band gap than silicon. By using an oxide semiconductor with a wider band gap than Ricon, the off state of the transistor can be controlled. The current in this state can be reduced.

[0112] The above oxide semiconductor preferably contains at least indium (In) or zinc (Zn). It is also In-M-Zn oxides (where M is Al, Ti, Ga, Ge, Y, Zr, Sn, It is an oxide semiconductor containing an oxide (such as a metal like La, Ce, or Hf). It is preferable.

[0113] In particular, the semiconductor layer has multiple crystalline portions, and the c-axis of the crystalline portion is the surface on which the semiconductor layer is formed. Alternatively, an acid oriented perpendicular to the upper surface of the semiconductor layer and having no grain boundaries between adjacent crystalline regions. It is preferable to use a crystalline semiconductor film.

[0114] By using such materials as semiconductor layers, fluctuations in electrical properties are suppressed, resulting in high reliability. This makes it possible to create a transistor.

[0115] Furthermore, due to its low off-current, the transistor having the aforementioned semiconductor layer can be used to... This makes it possible to retain the charge stored in the capacity over a long period of time. By applying a generator to each pixel, the gradation of the image displayed in each display area is maintained while driving It also becomes possible to shut down the circuit. As a result, it is possible to realize electronic devices with extremely reduced power consumption. It can be expressed.

[0116] It is preferable to provide an undercoat to stabilize the characteristics of the transistor. The undercoat may be: Inorganic silicon oxide films, silicon nitride films, silicon oxide-nitride films, silicon nitride-oxide films, etc. It can be fabricated using an insulating film, either as a single layer or in a multilayer configuration. The underlayer is fabricated by sputtering. CVD (Chemical Vapor Deposition) method (Plasma CVD method) , thermal CVD method, MOCVD (Metal Organic CVD) method, ALD ( Formed using methods such as Atomic Layer Deposition, coating, and printing. Yes, it is possible. However, a base coat does not need to be applied unless necessary.

[0117] Note that FET623 is one of the transistors formed in the drive circuit section 601. Furthermore, the drive circuit is formed using various CMOS, PMOS, or NMOS circuits. This is sufficient. Furthermore, this embodiment shows a driver-integrated type in which the drive circuit is formed on the substrate. However, this is not always necessary, and the drive circuit can be formed externally rather than on the circuit board. .

[0118] Furthermore, the pixel section 602 includes a switching FET 611 and a current control FET 612 and its drive It is formed by a plurality of pixels, each including a first electrode 613 electrically connected to the rain. However, it is not limited to this, and can also be used as a pixel unit combining three or more FETs and a capacitive element. good.

[0119] Furthermore, an insulator 614 is formed covering the end of the first electrode 613. Here, positive It can be formed by using a photosensitive acrylic resin film of a mold.

[0120] Furthermore, in order to ensure good coverage of the EL layer and other layers formed later, the upper end of the insulator 614 is Alternatively, a curved surface with curvature is formed at the lower end. For example, the material of the insulator 614 and When a positive-type photosensitive acrylic is used, the radius of curvature (0.) is only at the upper end of the insulator 614. It is preferable to have a curved surface having a thickness of 2 μm to 3 μm. Also, as the insulator 614, Either a negative-type or positive-type photosensitive resin can be used.

[0121] An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. Here, the material used for the first electrode 613 which functions as an anode is a material with a work function of It is desirable to use large materials. For example, ITO film or silicon-containing indigo Indium oxide film, indium oxide film containing 2-20 wt% zinc oxide, titanium nitride film, In addition to monolayer films such as chromium films, tungsten films, zinc films, and Pt films, titanium nitride films and aluminum films are also available. Lamination with a film mainly composed of aluminum, titanium nitride film and aluminum film and titanium nitride A three-layer structure with a film can be used. Furthermore, a laminated structure can be used as a wiring resistor. It has low noise levels, provides good ohmic contact, and can even function as an anode. .

[0122] Furthermore, the EL layer 616 was coated using a vapor deposition method with a vapor deposition mask, an inkjet method, and a spin coating method. It is formed by various methods such as those described in Embodiment 1. The EL layer 616 is formed by the structure described in Embodiment 1. It contains the following: In addition, other materials constituting the EL layer 616 include low molecular weight compounds, This may be a high-molecular-weight compound (including oligomers and dendrimers).

[0123] Furthermore, the material used for the second electrode 617, which is formed on the EL layer 616 and functions as a cathode. Examples include materials with a low work function (Al, Mg, Li, Ca, or alloys and compounds thereof) It is preferable to use materials (MgAg, MgIn, AlLi, etc.). Note that the EL layer 61 If the light generated in 6 passes through the second electrode 617, the second electrode 617 is defined as the film thickness. A thin metal film and a transparent conductive film (ITO, zinc oxide containing 2-20 wt%). Using a lamination process with indium tin oxide containing zinc and silicon (zinc oxide (ZnO), etc.) That would be good.

[0124] Furthermore, the first electrode 613, the EL layer 616, and the second electrode 617 form a light-emitting element. The light-emitting element is the light-emitting element described in Embodiment 1. The pixel section is a plurality Although light-emitting elements are formed, in the light-emitting device of this embodiment, Embodiment 1 The light-emitting element described above may include both light-emitting elements having other configurations.

[0125] Furthermore, by bonding the sealing substrate 604 to the element substrate 610 with the sealing material 605, A light-emitting element is placed in the space 607 surrounded by the sub-substrate 610, the sealing substrate 604, and the sealing material 605. The structure is equipped with 618. Furthermore, the space 607 is filled with a filler material. In addition to cases where inert gases (such as nitrogen or argon) are used for filling, this also applies when sealing materials are used for filling. Yes, it is. A recess is formed in the sealing substrate, and a desiccant is placed there to suppress deterioration due to moisture. It can be controlled, making it a desirable configuration.

[0126] Furthermore, it is preferable to use epoxy resin or glass frit for the sealing material 605. These materials should ideally be as impermeable to moisture and oxygen as possible. In addition to glass substrates and quartz substrates, other materials can be used for the encapsulating substrate 604, such as FRP (Fiber Reinforced Plastic). reinforced plastics, PVF (polyvinyl fluoride), polyester A plastic substrate made of tel or acrylic can be used.

[0127] Although not shown in Figure 2, a protective film may be provided on the second electrode. The protective film is an organic resin film. It can be formed with an inorganic insulating film. Also, the exposed portion of the sealing material 605 can be covered with A protective film may be formed. Furthermore, the protective film may be on the surface and sides of the pair of substrates, a sealing layer, and an insulating layer. It can be installed to cover exposed surfaces such as the margin layer.

[0128] The protective film can be made of a material that is impermeable to impurities such as water. This effectively suppresses the diffusion of impurities such as these from the outside to the inside.

[0129] Materials that make up the protective film include oxides, nitrides, fluorides, sulfides, ternary compounds, and metals. Alternatively, polymers can be used, for example, aluminum oxide, hafnium oxide, etc. Phenium silicate, lanthanum oxide, silicon oxide, strontium titanate, tantalum oxide Titanium dioxide, zinc oxide, niobium oxide, zirconium oxide, tin oxide, yttrium oxide cerium oxide, scandium oxide, erbium oxide, vanadium oxide, or indi oxide Materials containing um, etc., as well as aluminum nitride, hafnium nitride, silicon nitride, tantalum nitride, nitrogen Includes titanium dioxide, niobium nitride, molybdenum nitride, zirconium nitride, or gallium nitride, etc. Materials, nitrides containing titanium and aluminum, oxides containing titanium and aluminum oxides containing aluminum and zinc, sulfides containing manganese and zinc, cerium oxides Strontium-containing sulfides, erbium and aluminum-containing oxides, and Materials containing oxides, etc., including lium and zirconium can be used.

[0130] The protective film can be formed using a film deposition method that provides good step coverage. This is preferable. One such method is atomic layer deposition (ALD). There is a deposition method. Protecting materials that can be formed using the ALD method. It is preferable to use it for membranes. By using the ALD method, a dense membrane can be created with cracks and pinholes. A protective film can be formed with reduced defects or with a uniform thickness. Also, This reduces the damage inflicted on the processed material when forming a protective film.

[0131] For example, by forming a protective film using the ALD method, surfaces with complex uneven shapes, or taps can be formed. A uniform and low-defect protective film can be formed on the top, sides, and back surfaces of the panel. .

[0132] As described above, a light-emitting device made using the light-emitting element described in Embodiment 1 can be obtained. It is possible.

[0133] The light-emitting device in this embodiment uses the light-emitting element described in Embodiment 1, therefore, A light-emitting device with desirable characteristics can be obtained. Specifically, the light-emitting device described in Embodiment 1 Since the element is a light-emitting element with a long lifespan, it can be used to create a highly reliable light-emitting device. Furthermore, the light-emitting device using the light-emitting element described in Embodiment 1 has good luminous efficiency, so power consumption It is possible to make it into a small light-emitting device.

[0134] Figure 3 shows a light-emitting element that emits white light, with a colored layer (color filter) provided. An example of a light-emitting device that has been made full-color is shown. Figure 3(A) shows the substrate 1001 and the underlying insulation. Film 1002, gate insulating film 1003, gate electrodes 1006, 1007, 1008, first Interlayer insulating film 1020, second interlayer insulating film 1021, peripheral portion 1042, pixel portion 1040, drive Dynamic circuit section 1041, first electrodes 1024W, 1024R, 1024G, 102 4B, partition wall 1025, EL layer 1028, second electrode 1029 of light-emitting element, sealing substrate 103 1. The sealing material 1032 and other components are shown in the diagram.

[0135] Furthermore, Figure 3(A) shows the colored layers (red colored layer 1034R, green colored layer 1034G, blue). The colored layer 1034B is provided on a transparent substrate 1033. Also, the black matrix 1 A 035 layer may be further provided. Transparent substrate 1 provided with a colored layer and a black matrix. 033 is aligned and fixed to substrate 1001. Note that the colored layer and black matrix Kus 1035 is covered with an overcoat layer 1036. Also, in Figure 3(A) This consists of a light-emitting layer that allows light to escape to the outside without passing through the colored layers, and a layer that allows light to escape to the outside by passing through the colored layers of each color. There is a light-emitting layer, and light that does not pass through the colored layer is white, while light that passes through the colored layer is red, green, and blue. Therefore, images can be represented using four colored pixels.

[0136] Figure 3(B) shows the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer Example of forming layer 1034B) between the gate insulating film 1003 and the first interlayer insulating film 1020. This was shown. Thus, the colored layer is provided between the substrate 1001 and the sealing substrate 1031. That's good too.

[0137] Furthermore, in the light-emitting device described above, light is taken to the substrate 1001 side on which the FET is formed. Although a light-emitting device with a bottom-emission structure was used, the light emission was taken from the sealing substrate 1031 side. It can also be used as a light-emitting device with a projection structure (top emission type). A cross-sectional view of the light-emitting device is shown in Figure 4. In this case, the substrate 1001 is a substrate that does not transmit light. This can be done. Until the connecting electrode that connects the FET and the anode of the light-emitting element is fabricated, the bottom edge It is formed in the same way as a mission-type light-emitting device. Then, the third interlayer insulating film 1037 is attached to electrode 1 It is formed by covering 022. This insulating film may also play a planar role. Third interlayer insulating The border film 1037 can be formed using the same material as the second interlayer insulating film, as well as other known materials. It is possible.

[0138] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are the anodes here. However, it can also be a cathode. Also, a top-emission type light-emitting device as shown in Figure 4. In this case, it is preferable that the first electrode be a reflective electrode. The configuration of the EL layer 1028 is as follows: The configuration is as described in Embodiment 1 as the EL layer 103, and the white light emission is The device structure will be such that it can be obtained.

[0139] In the top emission structure shown in Figure 4, the colored layer (red colored layer 1034R, green colored layer) The sealing is performed using a sealing substrate 1031 having a color layer 1034G and a blue colored layer 1034B. This is possible. The encapsulation substrate 1031 has a black matrix positioned between the pixels. A colored layer (red colored layer 1034R, green colored layer 1034G) may be provided. The blue colored layer (1034B) and the black matrix are formed by the overcoat layer (1036). It may be covered. Furthermore, the sealing substrate 1031 shall be a light-transmitting substrate. Furthermore, while we have shown an example of full-color display using four colors—red, green, blue, and white—this is not particularly limited to... Alternatively, full-color displays may be performed using four colors: red, yellow, green, and blue, or three colors: red, green, and blue.

[0140] In top-emission type light-emitting devices, a microcavity structure can be suitably applied. A light-emitting element having a microcavity structure has a first electrode as a reflective electrode and a second electrode as a semipermeable electrode. This is obtained by using hyper- and semi-reflective electrodes. There is a small gap between the reflective electrode and the semi-transparent / semi-reflective electrode. It has at least an EL layer and at least an emissive layer that forms an emissive region.

[0141] The reflective electrode has a visible light reflectance of 40% to 100%, preferably 70% to 100%. It is %, and its resistivity is 1 × 10⁻⁶. -2 Assume the membrane is less than Ωcm in diameter. Also, semipermeable... The semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably 40% to 70%. , and its resistivity is 1 × 10 -2 Assume the membrane is less than Ωcm in diameter.

[0142] The light emitted from the light-emitting layer contained in the EL layer is reflected by the reflective electrode and the semi-transmitting / semi-reflective electrode. It is reflected and resonates.

[0143] The light-emitting element can change the thickness of the transparent conductive film, the aforementioned composite material, the carrier transport material, etc. This allows us to change the optical distance between the reflective electrode and the semitransmissive / semi-reflective electrode. Between the reflective electrode and the semitransmissive / semi-reflective electrode, the light of the resonant wavelength is amplified, and the resonance is prevented. It can attenuate light of a specific wavelength.

[0144] Furthermore, the light reflected back by the reflective electrode (the first reflected light) is semi-transmitted from the light-emitting layer. • Because it causes significant interference with the light (first incident light) that directly enters the semi-reflecting electrode, the reflective electrode and The optical distance of the light-emitting layer is (2n-1)λ / 4 (where n is a natural number greater than or equal to 1, and λ is amplified). It is preferable to adjust the wavelength of the emitted light. By adjusting the optical distance, the first By aligning the phase of the reflected light and the first incident light, the light emitted from the light-emitting layer can be further amplified. ru.

[0145] Furthermore, in the above configuration, even if the EL layer has a structure with multiple light-emitting layers, a single light-emitting layer The structure may also have layers, for example, in combination with the tandem light-emitting element configuration described above. Therefore, multiple EL layers are provided in a single light-emitting element, with a charge generation layer in between, and each EL layer has a single Alternatively, it may be applied to a configuration that forms multiple light-emitting layers.

[0146] Having a microcavity structure enhances the emission intensity in the front direction at specific wavelengths. This makes it possible to reduce power consumption. Furthermore, the four sub-colors red, yellow, green, and blue are used. In the case of a light-emitting device that displays images as is, in addition to the brightness enhancement effect of yellow light emission, all pixels By applying a microcavity structure tailored to the wavelength of each color, a light-emitting device with excellent characteristics can be produced. It can be placed there.

[0147] The light-emitting device in this embodiment uses the light-emitting element described in Embodiment 1, therefore, A light-emitting device with desirable characteristics can be obtained. Specifically, the light-emitting device described in Embodiment 1 Since the element is a light-emitting element with a long lifespan, it can be used to create a highly reliable light-emitting device. Furthermore, the light-emitting device using the light-emitting element described in Embodiment 1 has good luminous efficiency, so power consumption It is possible to make it into a small light-emitting device.

[0148] Up to this point, we have explained active-matrix light-emitting devices, but from here on we will discuss passive devices. A matrix-type light-emitting device will be described. Figure 5 shows a passive light-emitting device fabricated by applying the present invention. This shows a matrix-type light-emitting device. Note that Figure 5(A) is a perspective view showing the light-emitting device, Figure 5( B) is a cross-sectional view obtained by cutting Figure 5(A) along the XY line. In Figure 5, on the substrate 951, An EL layer 955 is provided between electrode 952 and electrode 956. The end of electrode 952 is It is covered with an insulating layer 953. And a partition layer 954 is provided on top of the insulating layer 953. The side walls of the partition layer 954, as they approach the substrate surface, have a gap between one side wall and the other side wall. It has a slope that narrows as the partition becomes narrower. In other words, the cross-section of the partition wall layer 954 in the short-side direction is It is a shape, and the bottom edge (which faces the same direction as the surface direction of the insulating layer 953 and is in contact with the insulating layer 953) ) is the upper edge (the edge that faces the same direction as the surface direction of the insulating layer 953 and does not come into contact with the insulating layer 953). It is shorter than that. In this way, by providing the partition layer 954, the light-emitting element caused by static electricity, etc. This can prevent defects. Also, in the case of passive matrix type light-emitting devices, the implementation form The light-emitting element described in State 1 is used, and the light-emitting device is highly reliable or has low power consumption. It can be used as an optical device.

[0149] The light-emitting device described above uses a number of tiny light-emitting elements arranged in a matrix. Because it can be controlled, it is suitable for use as a display device for displaying images. It is a device.

[0150] Furthermore, this embodiment can be freely combined with other embodiments.

[0151] (Embodiment 3) In this embodiment, an example of using the light-emitting element described in Embodiment 1 as an illumination device is shown in Figure 6. I will explain while illuminating. Figure 6(B) is a top view of the lighting device, and Figure 6(A) is the same as in Figure 6(B). This is a cross-sectional view of ef.

[0152] The lighting device in this embodiment has a light-transmitting substrate 400 which is a support, and a first An electrode 401 is formed. The first electrode 401 is the first electrode 10 in Embodiment 1. This corresponds to 1. When light is extracted from the first electrode 401 side, the first electrode 401 is light-transmitting. It is formed from a material having [a certain characteristic].

[0153] A pad 412 for supplying voltage to the second electrode 404 is formed on the substrate 400.

[0154] An EL layer 403 is formed on the first electrode 401. The EL layer 403 is in Embodiment 1 The configuration of the EL layer 103 in the light-emitting units 511, 512 and the charge generation layer 513 This corresponds to a combined configuration, etc. Please refer to the relevant description for details on these configurations.

[0155] The EL layer 403 is covered to form the second electrode 404. The second electrode 404 is in Embodiment 1. This corresponds to the second electrode 102. When light emission is taken from the first electrode 401 side, the second The electrode 404 is formed of a highly reflective material. The second electrode 404 is pad 412 Voltage is supplied by connecting it to it.

[0156] The above describes a light-emitting element having a first electrode 401, an EL layer 403, and a second electrode 404. The lighting device shown in the form of installation has a light-emitting element that has high luminous efficiency. Therefore, the lighting device in this embodiment can be a lighting device with low power consumption.

[0157] A substrate 400 on which a light-emitting element having the above configuration is formed, and a sealing substrate 407 are sealed together with a sealing material 4 The lighting device is completed by fixing and sealing it using 05 and 406. Sealing material 40 5. Either 406 or 406 is acceptable. Also, the inner sealant 406 (Figure 6(B) A desiccant can also be mixed in (not shown), which allows it to absorb moisture. This will lead to improved reliability.

[0158] Furthermore, the pad 412 and a portion of the first electrode 401 are extended outside the sealing materials 405 and 406. By providing it, it can be used as an external input terminal. Also, a converter can be placed on top of it. An IC chip 420 or similar, which incorporates such features, may also be provided.

[0159] As described above, the lighting device described in this embodiment uses the light-emitting element described in Embodiment 1 as the EL element. This allows for a highly reliable light-emitting device. Furthermore, it is a light-emitting device with low power consumption. It can be placed there.

[0160] (Embodiment 4) In this embodiment, an example of an electronic device that includes the light-emitting element described in Embodiment 1 as a part thereof... The light-emitting element described in Embodiment 1 has a good lifespan and is a reliable light-emitting element. It is a child. As a result, the electronic device described in this embodiment has a reliable light-emitting part. It can be made into an electronic device.

[0161] Examples of electronic devices to which the above light-emitting element is applied include television equipment (television, or television). (also called a revision receiver), monitors for computers, digital cameras, digital Video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) ), portable game consoles, personal digital assistants, sound playback devices, large game machines such as pachinko machines, etc. These include [examples of electronic devices]. Specific examples of these electronic devices are shown below.

[0162] Figure 7(A) shows an example of a television system. The television system is housed in a 710 enclosure. The display unit 7103 is incorporated into part 1. Also, the housing is connected by the stand 7105. This shows the configuration supporting 7101. The display unit 7103 can display video. The display unit 7103 is capable of arranging the light-emitting elements described in Embodiment 1 in a matrix. It is composed of.

[0163] The television equipment can be operated using the control switches on the housing 7101 or a separate remote control. This can be done using the device 7110. The remote control device 7110 has an operation key 7109. This allows you to control the channel and volume, and the video displayed on the display unit 7103 It can be operated. Also, the remote control unit 7110 A display unit 7107 that displays the information output from the unit may also be provided.

[0164] The television system shall consist of a receiver, modem, etc. It can receive television broadcasts, and also communicate via wired or wireless connection through a modem. By connecting to a network, one-way (sender to receiver) or two-way (sender to receiver) communication is possible. It is also possible to communicate information between recipients, or between recipients themselves.

[0165] Figure 7(B1) is a computer, consisting of the main unit 7201, the casing 7202, the display unit 7203, and a key - Includes board 7204, external connection port 7205, pointing device 7206, etc. Furthermore, this computer arranges the light-emitting elements described in Embodiment 1 in a matrix. It is manufactured by using it in the display unit 7203. The computer in Figure 7(B1) is in Figure 7( It may also be in a form like B2). The computer in Figure 7(B2) has a keyboard 720 4. A second display unit 7210 is provided instead of the pointing device 7206. The second display unit 7210 is a touch panel, and the information displayed on the second display unit 7210 is Input can be performed by operating the displayed input screen with a finger or a special pen. Furthermore, the second display unit 7210 can display not only input information but also other images. The display unit 7203 may also be a touch panel. The two screens are connected by a hinge. This prevents problems such as scratching or damaging the screen during storage or transport. This can also prevent the occurrence of negativity.

[0166] Figure 7(C) shows a portable gaming machine, which consists of two cabinets, cabinet 7301 and cabinet 7302. The housing 7301 is connected in an openable and closable manner by the connecting part 7303. A display unit 7304, which is made by arranging the light-emitting elements described in Embodiment 1 in a matrix, is incorporated. Furthermore, the display unit 7305 is incorporated into the housing 7302. Also, as shown in Figure 7(C), Other components of the gaming machine include a speaker unit 7306, a recording medium insertion unit 7307, and an LED lamp 73 08. Input means (operation key 7309, connection terminal 7310, sensor 7311 (force, displacement, position) Location, speed, acceleration, angular velocity, rotational speed, distance, light, liquid, magnetism, temperature, chemicals, sound, time Hardness, electric field, electric current, voltage, power, radiation, flow rate, humidity, gradient, vibration, odor, or infrared radiation. It includes a function to measure (including a microphone 7312), etc. The configuration of the strip-type gaming machine is not limited to those described above, and includes at least the display unit 7304 and the display unit 7 The light-emitting elements described in Embodiment 1 are arranged in a matrix on both or one of the 305. It is sufficient to use a manufactured display unit, and the configuration may include other auxiliary equipment as appropriate. Yes, it is possible. The portable gaming machine shown in Figure 7(C) has a program or data recorded on the recording medium. It has functions to read data and display it on the display unit, and to communicate wirelessly with other portable gaming machines to exchange information. It has a sharing function. However, the functions of the portable gaming machine shown in Figure 7(C) are not limited to this. It is not limited to that and can have various functions.

[0167] Figure 7(D) shows an example of a mobile terminal. The mobile phone is incorporated into the housing 7401. In addition to the display unit 7402, there are operation buttons 7403, an external connection port 7404, and a speaker 740 5. It is equipped with a microphone 7406, etc. Note that the mobile phone 7400 is described in Embodiment 1. It has a display unit 7402 made by arranging the mounted light-emitting elements in a matrix.

[0168] The mobile terminal shown in Figure 7(D) allows users to input information by touching the display unit 7402 with their fingers or other objects. It can also be configured to allow for making phone calls or composing emails. Operations such as this can be performed by touching the display unit 7402 with a finger or the like.

[0169] The display unit 7402 has three main modes. The first is a display that primarily displays images. The first mode is display mode, the second is input mode which is primarily for inputting information such as characters. The third is display mode. This is a display + input mode, which is a combination of two modes: display mode and input mode.

[0170] For example, when making a phone call or composing an email, the display unit 7402 is used for text input. The primary mode is text input, and you should perform the input operation for the characters displayed on the screen. It is preferable to display a keyboard or number buttons on most of the screen of the display unit 7402. It seems so.

[0171] Furthermore, the mobile device has sensors inside that detect tilt, such as a gyroscope and an accelerometer. By installing the device, the orientation of the mobile terminal (portrait or landscape) is determined, and the screen display of the display unit 7402 is displayed accordingly. The display can be set to switch automatically.

[0172] Furthermore, screen modes can be switched by touching the display unit 7402 or by operating the housing 7401. This is done by operating button 7403. Also, the type of image displayed on display unit 7402 Therefore, it is also possible to switch between them. For example, the image signal displayed on the display unit is a video signal. Switch to display mode if it's data, or to input mode if it's text data.

[0173] Furthermore, in input mode, the signal detected by the optical sensor of the display unit 7402 is detected and displayed If there is no input via touch operation on unit 7402 for a certain period of time, the screen mode will be changed to input mode. You may also control the system to switch from that display mode to a different mode.

[0174] The display unit 7402 can also function as an image sensor. For example, the display unit 74 By touching device 02 with the palm or fingers, the user can be authenticated by capturing images of their palm print, fingerprints, etc. Furthermore, the display unit may have a backlight that emits near-infrared light or a sensing light that emits near-infrared light. Using the appropriate source, it is also possible to image finger veins, palmar veins, and other veins.

[0175] The configuration shown in this embodiment is a combination of the configurations shown in Embodiments 1 to 4 as appropriate. They can be used together.

[0176] As described above, the scope of application of the light-emitting device equipped with the light-emitting element described in Embodiment 1 is extremely broad. This light-emitting device can be applied to electronic devices in all fields. (Described in Embodiment 1) By using light-emitting elements, highly reliable electronic devices can be obtained.

[0177] Figure 8 shows an example of a liquid crystal display device in which the light-emitting element described in Embodiment 1 is applied as a backlight. Yes, there is. The liquid crystal display device shown in Figure 8 consists of a housing 901, a liquid crystal layer 902, and a backlight unit. It has 903 and a housing 904, and the liquid crystal layer 902 is connected to the driver IC 905. Furthermore, the backlight unit 903 uses the light-emitting element described in Embodiment 1. Current is supplied through terminal 906.

[0178] By applying the light-emitting element described in Embodiment 1 to the backlight of a liquid crystal display device, A backlight with reduced power consumption can be obtained. Furthermore, by using the light-emitting element described in Embodiment 1 This allows for the fabrication of surface-emitting lighting devices, and also enables large-area applications. This makes it possible to increase the area of ​​black lights, and also to increase the area of ​​liquid crystal display devices. Furthermore, Since the light-emitting device to which the light-emitting element described in the first embodiment is applied can be made thinner compared to conventional devices, This also makes it possible to make display devices thinner.

[0179] Figure 9 shows an example in which the light-emitting element described in Embodiment 1 is used in a desk lamp, which is a lighting device. The desk lamp shown in Figure 9 has a housing 2001 and a light source 2002, and the light source 2002 and Alternatively, the lighting device described in Embodiment 3 may be used.

[0180] Figure 10 shows an example in which the light-emitting element described in Embodiment 1 is used as an indoor lighting device 3001. Yes. The light-emitting element described in Embodiment 1 is a highly reliable light-emitting element, therefore it is reliable. It can be used as a lighting device. Furthermore, the light-emitting element described in Embodiment 1 can be made to have a large area. Therefore, it can be used as a large-area lighting device. Also, the emission described in Embodiment 1 Because the optical element is thin, it can be used in miniaturized lighting devices.

[0181] The light-emitting element described in Embodiment 1 can also be mounted on the windshield or dashboard of an automobile. This can be done. Figure 11 shows the light-emitting element described in Embodiment 1 on the windshield of an automobile or a dash One embodiment for use on a dashboard is shown. Display areas 5000 to 5005 are in the actual form. This is a display provided using the light-emitting element described in Form 1.

[0182] Display area 5000 and display area 5001 are in an embodiment provided on the windshield of an automobile. This is a display device equipped with the light-emitting element described in 1. The light-emitting element described in Embodiment 1 is the first By fabricating the first electrode and the second electrode with translucent electrodes, the opposite side can be seen through. It can be used as a display device in a so-called see-through state. Therefore, even if it is installed on the windshield of a car, it can be installed without obstructing the view. This is possible. Furthermore, if transistors or other components for driving are provided, organic semiconductor materials may be used. Translucent transistors such as organic transistors and transistors using oxide semiconductors Using a Rangista would be a good idea.

[0183] Display area 5002 is a display equipped with the light-emitting element described in Embodiment 1, which is provided on the pillar portion. This is a display device. The display area 5002 displays images from an imaging device installed on the vehicle body. This allows for the correction of the view obstructed by the pillar. Similarly, the dash The display area 5003 on the board section provides a view of the outside of the car that is obstructed by the vehicle body. By displaying images from imaging devices installed in the area, blind spots are compensated for, and safety is enhanced. It is possible to project images in a way that complements the unseen parts, making the unnaturalness more natural. Safety checks can be performed without any sense of touch.

[0184] Display areas 5004 and 5005 display navigation information, speedometer, tachometer, and mileage. It can provide various other information such as fuel level, gear status, and air conditioning settings. The display items and layout can be changed as needed to suit the user's preferences. Oh, this information can also be provided in display areas 5000 to 5003. Display areas 5000 to 5005 can also be used as lighting devices.

[0185] Figures 12(A) and 12(B) show examples of foldable tablet devices. Figure 12 (A) is in the open state, and the tablet terminal consists of a housing 9630, a display unit 9631a, Display unit 9631b, display mode selector switch 9034, power switch 9035, power saving It has a force mode switching switch 9036, a fastener 9033, and an operating switch 9038. Furthermore, the tablet terminal displays the light-emitting device equipped with the light-emitting element described in Embodiment 1. It is manufactured by using it in either or both of section 9631a and display section 9631b.

[0186] The display unit 9631a can be partially designated as a touch panel area 9632a, and the displayed Data can be entered by touching the operation key 9637. Note that the display unit 9631 In case a, for example, one half of the area has a configuration that only has a display function, and the other half of the area is The diagram shows a configuration with touch panel functionality, but is not limited to this configuration. Display unit 9631 The entire area of ​​a may also be configured to have touch panel functionality. For example, display unit 963 The entire surface of 1a is used as a touch panel with keyboard buttons, and the display unit 9631b displays an image It can be used as a surface.

[0187] Furthermore, in the display unit 9631b, similar to the display unit 9631a, a part of the display unit 9631b This can be designated as the touch panel area 9632b. Also, the keyboard area of ​​the touch panel... By touching the location where the display toggle button 9639 is displayed with your finger or stylus, the display will change. Keyboard buttons can be displayed on the display unit 9631b.

[0188] Also, touching both the touch panel area 9632a and the touch panel area 9632b simultaneously is also possible. You can also input data.

[0189] Additionally, the display mode switch 9034 changes the display orientation, such as portrait or landscape. You can switch between modes, such as switching between black and white and color displays. Power saving mode switching... The Itch 9036 detects ambient light during use using a light sensor built into the tablet device. The display brightness can be optimized according to the amount of light. The tablet terminal uses optical sensors. In addition to the sensor, other detection devices such as gyroscopes, accelerometers, and other sensors that detect tilt are also used. It can be built-in.

[0190] Furthermore, Figure 12(A) shows an example where the display area of ​​display unit 9631b and display unit 9631a are the same. However, this is not particularly limited, and one size may be different from the other. The quality of these components may also differ. For example, one display panel may be capable of displaying higher resolution than the other. That is also acceptable.

[0191] Figure 12(B) shows the closed state, and in this embodiment, the tablet terminal has a housing. 9630, Solar cell 9633, Charge / discharge control circuit 9634, Battery 9635, DC-DC An example with a converter 9636 is shown. Note that in Figure 12(B), the charge / discharge control circuit 9634 As an example, a configuration having a battery 9635 and a DC-DC converter 9636 is shown. They are doing it.

[0192] Since the tablet device is foldable, the casing 9630 can be closed when not in use. Therefore, the display units 9631a and 9631b can be protected, thus providing durability. We can provide tablet devices that are highly durable and reliable from the perspective of long-term use.

[0193] In addition, the tablet devices shown in Figures 12(A) and 12(B) can also be used for various purposes. Features for displaying information (still images, videos, text images, etc.), calendar, date or time, etc. A function to display information on the display unit, and a touch input function to perform touch input operations or edit the information displayed on the display unit. It has functions such as power control and the ability to control processing by various software (programs). It is possible.

[0194] The solar cell 9633 mounted on the surface of the tablet device powers the touch panel. It can be supplied to the display unit or the video signal processing unit, etc. Note that the solar cell 9633 is If provided on one or two sides of the housing 9630, it allows for efficient charging of the battery 9635. This configuration is preferable because it allows for the implementation of the desired behavior.

[0195] Furthermore, the configuration and operation of the charge / discharge control circuit 9634 shown in Figure 12(B) are shown in Figure 12(C). The block diagram is shown and explained in Figure 12(C). The solar cell 9633 and battery 96 35. DC-DC converter 9636, converter 9638, switch SW1 to SW3, The display unit 9631 is shown, along with the battery 9635 and the DC-DC converter 9636. The converter 9638 and switches SW1 to SW3 control the charge / discharge cycle shown in Figure 12(B). This corresponds to the section of road 9634.

[0196] First, let's explain an example of operation when electricity is generated by the solar cell 9633 using ambient light. The electricity generated by the solar panel is converted to a DCD (Digital-to-Collar) voltage to charge the 9635 battery. The C converter 9636 performs either a boost or a buck. Then, the operation of the display unit 9631 is performed. When power charged by the solar cell 9633 is used, turn on switch SW1 and convert The 9638 will boost or lower the voltage to the required level for the display unit 9631. When you do not want to display anything on the display unit 9631, turn SW1 off and turn SW2 on. The configuration should be designed to charge the Terry 9635.

[0197] While the solar cell 9633 is shown as an example of a power generation method, the power generation method is not particularly limited. It is not limited to other power generation devices such as piezoelectric elements (piezoelectric elements) and thermoelectric elements (Peltier elements). The battery 9635 may be charged by some means. A contactless power transmission module that charges by sending and receiving power, or a combination of other charging methods. This configuration is also acceptable, and it does not require a means of generating electricity.

[0198] Furthermore, if the above-mentioned display unit 9631 is included, the tablet terminal will have the shape shown in Figure 12. Not limited.

[0199] Figures 13(A) to (C) also show a foldable portable information terminal 9310. Figure 13 (A) shows the portable information terminal 9310 in its unfolded state. Figure 13(B) shows the unfolded state or This shows the portable information terminal 9310 in an intermediate state, transitioning from one folded state to the other. Figure 13(C) shows the folded state of the personal digital assistant 9310. Personal digital assistant 9310 It offers excellent portability when folded and a seamless, wide display area when unfolded. This provides excellent readability in the display.

[0200] The display panel 9311 is supported by three housings 9315 connected by hinges 9313. The display panel 9311 is a touch panel equipped with a touch sensor (input device). It may also be an input / output device. In addition, the display panel 9311 is connected via the hinge 9313. By bending the two housings 9315, the mobile information terminal 9310 is unfolded. It can be reversibly transformed from a folded state. A light-emitting device according to one aspect of the present invention It can be used in the display panel 9311. Display area 931 in the display panel 9311 2 is the display area located on the side of the folded portable information terminal 9310. Area 9312 contains information icons and shortcuts to frequently used apps and programs. It can display information and allow for smoother information checking and app launching. ru. [Examples]

[0201] In this embodiment, the light-emitting element 1 and comparative light-emitting element 1 according to one aspect of the present invention described in Embodiment 1 This will be explained. The structural formulas of the organic compounds used in light-emitting element 1 and comparative light-emitting element 1 are shown below. show.

[0202] [ka]

[0203] (Method for fabricating light-emitting element 1) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0204] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0205] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0206] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0207] Next, on the hole injection layer 111, N-(1,1'-bipheny represented by the above structural formula (ii) is injected. Lu-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole- 3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) 20n The first hole transport layer 112-1 is formed by depositing to a thickness of m, and the first hole transport layer 112-1 shows 4-(1-naphthyl)-4'-phenyl represented by the above structural formula (iii). Triphenylamine (abbreviated as αNBA1BP) is deposited to a film thickness of 5 nm to create a second A hole transport layer 112-2 is formed, and the above structural formula (iv) is used on the second hole transport layer 112-2. The expressed 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carb A zole (abbreviated as PCPPn) is deposited to a thickness of 5 nm to form the third hole transport layer 112 -3 was formed.

[0208] Next, the 7-[4-(10-phenyl-9-antryl) represented by the above structural formula (v) Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above The structural formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3 -(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine n (abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCz) The light-emitting layer 113 is co-deposited at a 25 nm thickness so that PA:1,6mMemFLPAPrn) It was formed.

[0209] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0210] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 1 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0211] (Method for fabricating comparative light-emitting element 1) Comparative light-emitting element 1 consists of a first hole transport layer 112-1 and a second hole transport layer 1 Except for the addition of a 25nm PCBBiF film instead of the two layers of 12-2, it is the same as light-emitting element 1. It was fabricated in this way. In other words, the comparative light-emitting element 1 does not form a second hole transport layer 112-2. It can be called an element.

[0212] The element structures of light-emitting element 1 and comparative light-emitting element 1 are summarized in the table below.

[0213] [Table 1]

[0214] The light-emitting element 1 and the comparative light-emitting element 1 were placed in a glove box under a nitrogen atmosphere. The process of sealing the element with a glass substrate to prevent it from being exposed to the atmosphere (applying a sealing material around the element). Then, after UV treatment and heat treatment at 80°C for 1 hour during sealing, these light-emitting elements undergo initial characteristics Measurements were taken to assess performance and reliability. The measurements were performed at room temperature (in an atmosphere maintained at 25°C). That's it.

[0215] Figure 14 shows the luminance-current density characteristics of light-emitting element 1 and comparative light-emitting element 1, and the current efficiency-luminance characteristics. Figure 15 shows the luminance-voltage characteristics, Figure 16 shows the current-voltage characteristics, and Figure 17 shows the external quantum efficiency-luminance. The characteristics are shown in Figure 18, and the emission spectra are shown in Figure 19. Furthermore, the 1000 cd / m² values ​​for each light-emitting element are shown in Figure 18. m 2 Table 2 shows the main characteristics of the vicinity.

[0216] [Table 2]

[0217] As shown in Figures 14 to 19 and Table 2, the light-emitting element 1 in one aspect of the present invention has a second hole transport layer Compared to the comparative light-emitting element 1 which does not have 112-2, this blue light-emitting element has better driving voltage and efficiency. It was discovered that...

[0218] Additionally, the initial brightness is 5000 cd / m². 2 And, with respect to the driving time under the condition of constant current density A graph showing the change in brightness is shown in Figure 20. As shown in Figure 20, the light-emitting element of one aspect of the present invention The child light-emitting element 1 shows a significant decrease in brightness due to the accumulation of operating time compared to the comparative light-emitting element 1. It was found to be a small, long-lasting light-emitting element.

[0219] In the light-emitting element of this embodiment, the first to third hole transport materials, and the host material The HOMO levels of the luminescent materials are as shown in the table below. The LUMO levels were calculated based on cyclic voltammetry (CV) measurements. Calculation method The law is as follows:

[0220] The measuring device used is an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS model). A 600A or 600C was used. The solution used in the CV measurement was dehydrated dimethyl as the solvent. Aldrich Formamide (DMF) (manufactured by Aldrich Co., Ltd., 99.8%, catalog number; 227) Using 05-6), the supporting electrolyte is tetra-n-butylammonium perchlorate (nB u4NClO4) (manufactured by Tokyo Chemical Co., Ltd., catalog number: T0836) 100 mmol / Dissolve to a concentration of L, and then dissolve the sample to be measured to a concentration of 2 mmol / L. It was prepared by dissolving it. Furthermore, a platinum electrode (manufactured by BAS Corporation, PT) was used as the working electrode. E Platinum electrode) is used as an auxiliary electrode, and platinum electrode (manufactured by B.A.S. Co., Ltd., for VC-3 P A counter electrode (5 cm) is used, and Ag / Ag is used as the reference electrode. + Electrode (B.A.E.) A RE7 non-aqueous solvent reference electrode manufactured by S Corporation was used. The measurements were taken at room temperature (20°C). The measurements were performed at 25°C. The scan speed during CV measurement was standardized to 0.1V / sec. The oxidation potential Ea [V] and reduction potential Ec [V] were measured relative to the irradiated electrode. Ea is the oxidation- The intermediate potential of the reduction wave was used, and Ec was set as the intermediate potential of the reduction-oxidation wave. Here, the values ​​used in this embodiment The potential energy of the reference electrode relative to the vacuum level is -4.94 [eV]. Since it is known that the HOMO level [eV] = -4.94 - Ea, the LUMO level [eV The HOMO level and LUMO level can be determined from the equation ] = -4.94 - Ec. It is possible.

[0221] [Table 3]

[0222] As shown in the table, in the material used for the light-emitting element 1, the HOMO level of the second hole transport material is The HOMO level of the host material is deeper than the HOMO level of the first hole transport material, and the HOMO level of the host material is deeper than the HOMO level of the second hole. The HOMO level of the third hole transport material is deeper than the HOMO level of the host material. It is deeper than the HOMO level. Also, the HOMO level of the luminescent material is deeper than the HOMO level of the host material. It's also shallow.

[0223] The HOMO level of PCBBiF, the first hole transport material, is shallow at -5.36 eV, and HAT-C It can interact with the LUMO level of N at -4.41 eV, easily causing charge separation.

[0224] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and P There is a 0.33 eV difference in the HOMO level of CBBiF. On the other hand, the luminescent material 1,6 Since the HOMO level of mMemFLPAPrn is -5.40 eV, the difference is 0.04 It is eV. Since the difference in HOMO levels between the light-emitting material and the first hole transport material is small, A light-emitting element having a structure in which a hole transport layer 112-1 and a light-emitting layer 113 are in contact. When considering the possibility of a child, hole injection into the light-emitting material is likely to occur. However, direct emission When holes are injected into the light material, the holes are transported by the light-emitting material through the first hole transport layer 112-1 and emit light. The light-emitting region may become trapped at the layer interface, potentially accelerating degradation. The hole transport material in the hole transport layer 112-1 has difficulty entering the host material of the light-emitting layer. Therefore, holes accumulate in the hole transport material and electrons accumulate in the host material. Excyplexes, which have lower energy than luminescent materials, are found between hole transport materials and host materials. This can lead to the formation of a luminescence barrier, which can result in problems such as reduced luminescence efficiency.

[0225] In the light-emitting element 1, the second hole transport layer 112-2 has a shallower HOMO level than the host material. However, by using a second hole transport material with a deeper HOMO level than the first hole transport material... Therefore, first, holes are injected from the first hole transport layer 112-1 to the second hole transport layer 112-2. The HOMO level of the second hole transport material, αNBA1BP, is -5.52 eV. Furthermore, the difference with PCBBiF, the first hole transport material, is small at 0.16 eV. Therefore, Holes are smoothly injected from the first hole transport layer 112-1 to the second hole transport layer 112-2. It will be done.

[0226] Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. Therefore, a barrier of approximately 0.17 eV exists between the second hole transport material and the host material. Normally, holes would be injected without any problems, but the difference is that the H of the light-emitting material contained in the light-emitting layer 113 The OMO level is -5.40 eV and there is no barrier. Therefore, the holes ultimately enter the host material. It is preferentially injected into the light-emitting material. If holes are injected directly into the light-emitting material, as described above... This can easily lead to problems such as accelerated degradation and decreased luminous efficiency.

[0227] Therefore, in the light-emitting element 1, which is a light-emitting element according to one aspect of the present invention, the second hole transport layer 112-2 and A third hole transport layer 112-3 is provided between the light-emitting layer 113 and the third hole transport layer. The HOMO level of PCPPn, the third hole transport material included in 112-3, is -5.80. The eV is located deeper than the host material. Therefore, there is no barrier to hole injection into the host material. Furthermore, the mixing ratio of the host material and the light-emitting material prioritizes the injection of holes into the host material. The difference in HOMO levels with the second hole transport material is 0.28 eV (0.3 eV to one significant figure). (within) and the injection of holes from the second hole transport material to the third hole transport material is also without problems. It will be done.

[0228] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the emission region Because the light distribution is spread across the light-emitting layer 113 rather than being concentrated in one area, degradation is not accelerated and the lifespan is not extended. As a result, it became a light-emitting element with good luminescence efficiency.

[0229] On the other hand, the comparative light-emitting element 1 lacks the second hole transport layer 112-2, thus the first There is a large HOMO level difference between the first hole transport layer 112-1 and the third hole transport layer 112-3. This is occurring. As a result, it becomes difficult for holes to be injected into the light-emitting layer 113, and the driving voltage increases. It rises. Also, because it becomes more difficult for holes to be injected, electrons move between the light-emitting layer 113 and the hole transport layer. This can lead to problems such as electrons accumulating at the interface and leaking into the hole transport layer. When this occurs, the light-emitting region becomes uneven, which can negatively affect the lifespan of the light-emitting element. Also, electron When the dopant leaks into the hole transport layer, carrier recombination also occurs in the hole transport layer, and the dopant This can lead to a decrease in luminescence efficiency due to a relative decrease in the probability of emission, as well as deterioration of hole transport materials. This may cause a decrease in lifespan. Thus, the light-emitting element 1 in one embodiment of the present invention Because these drawbacks were effectively suppressed, the light-emitting element exhibited very good characteristics. That's what happened. [Examples]

[0230] In this embodiment, the light-emitting element 2 and light-emitting element 3 of one aspect of the present invention described in Embodiment 1 are as follows: Let me explain. The structural formulas of the organic compounds used in light-emitting element 2 and light-emitting element 3 are shown below.

[0231] [ka]

[0232] (Method for fabricating light-emitting element 2) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0233] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0234] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0235] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0236] Next, on the hole injection layer 111, N-(1,1'-bipheny represented by the above structural formula (ii) is injected. Lu-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole- 3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) 10n The first hole transport layer 112-1 is formed by depositing to a thickness of m, and the first hole transport layer 112-1 shows 4-phenyl-4'-(9-phenyl represented by the above structural formula (viii) Fluoren-9-yl)triphenylamine (abbreviated as BPAFLP) to a film thickness of 5 nm A second hole transport layer 112-2 is formed by deposition, and on the second hole transport layer 112-2 The above structural formula (ix) represents 3,3'-(naphthalene-1,4-diyl)bis(9-f Enyl-9H-carbazole (abbreviation: PCzN2) is deposited to a film thickness of 15 nm. A third hole transport layer 112-3 was formed.

[0237] Next, the 7-[4-(10-phenyl-9-antryl)f represented by the above structural formula (v) [enyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above composition The formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3- (9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine (Abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCzP A: 25 nm co-deposited to form the light-emitting layer 113 (A: 1,6 mMemFLPAPrn) I did it.

[0238] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0239] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 2 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0240] (Method for fabricating the light-emitting element 3) The light-emitting element 3 uses αNBA to transport the BPAFLP of the second hole transport layer 112-2 in the light-emitting element 2. Aside from changing to 1BP, it was fabricated in the same way as light-emitting element 2.

[0241] The element structures of light-emitting element 2 and light-emitting element 3 are summarized in the table below.

[0242] [Table 4]

[0243] The light-emitting element 2 and light-emitting element 3 are placed in a glove box under a nitrogen atmosphere, and the light-emitting elements are large The process of sealing the element with a glass substrate to prevent exposure to the elements (applying a sealing material around the element, After UV treatment and heat treatment at 80°C for 1 hour during sealing, the initial characteristics of these light-emitting elements are determined. Reliability measurements were performed. The measurements were conducted at room temperature (in an atmosphere maintained at 25°C). .

[0244] Figure 21 shows the brightness-current density characteristics of light-emitting elements 2 and 3, and Figure 2 shows the current efficiency-brightness characteristics. Figure 23 shows the luminance-voltage characteristics, Figure 24 shows the current-voltage characteristics, and Figure 24 shows the external quantum efficiency-luminance characteristics. Figure 25 shows the image, and Figure 26 shows the emission spectrum. Furthermore, the 1000 cd / m² emission spectrum of each light-emitting element is shown. 2 Attached Table 5 shows the main characteristics in recent times.

[0245] [Table 5]

[0246] From Figures 21 to 26 and Table 4, it can be seen that all of the light-emitting elements are blue light-emitting elements with good characteristics. That's what I found out.

[0247] Additionally, the initial brightness is 5000 cd / m². 2 Assuming a constant current density, the driving time is as follows: A graph showing the change in brightness is shown in Figure 27. As shown in Figure 27, a light-emitting element according to one aspect of the present invention The light-emitting elements 2 and 3 exhibit little decrease in brightness due to the accumulation of operating time and have a good lifespan. It was found to be a light-emitting element.

[0248] In the light-emitting element of this embodiment, the first to third hole transport materials, and the host material The HOMO levels of the luminescent materials are as shown in the table below. The LUMO levels were calculated based on cyclic voltammetry (CV) measurements. Calculation method The procedure is the same as in Example 1.

[0249] [Table 6]

[0250] [Table 7]

[0251] As shown in the table, in the materials used for light-emitting element 2 and light-emitting element 3, the second hole transport material H The OMO level is deeper than the HOMO level of the first hole transport material, and the HOMO level of the host material is deeper than the HOMO level of the first hole transport material. The HOMO level is deeper than that of the second hole transport material, and the HOMO level of the third hole transport material is It is deeper than the HOMO level of the host material. Also, the HOMO level of the luminescent material is deeper than the H level of the host material. It is shallower than the OMO level.

[0252] The HOMO level of PCBBiF, the first hole transport material, is shallow at -5.36 eV, and HAT-C It can interact with the LUMO level of N at -4.41 eV, easily causing charge separation.

[0253] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and P There is a 0.33 eV difference in the HOMO level of CBBiF. On the other hand, the luminescent material 1,6 Since the HOMO level of mMemFLPAPrn is -5.40 eV, the difference is 0.04 It is eV. Since the difference in HOMO levels between the light-emitting material and the first hole transport material is small, A light-emitting element having a structure in which a hole transport layer 112-1 and a light-emitting layer 113 are in contact. When considering the possibility of a child, hole injection into the light-emitting material is likely to occur. However, direct emission When holes are injected into the light material, the holes are transported by the light-emitting material through the first hole transport layer 112-1 and emit light. The light-emitting region may become trapped at the layer interface, potentially accelerating degradation. The hole transport material in the hole transport layer 112-1 has difficulty entering the host material of the light-emitting layer. Therefore, holes accumulate in the hole transport material and electrons accumulate in the host material. Excyplexes, which have lower energy than luminescent materials, are found between hole transport materials and host materials. This can lead to the formation of a luminescence barrier, which can result in problems such as reduced luminescence efficiency.

[0254] In light-emitting elements 2 and 3, the second hole transport layer 112-2 is made of H material, which is higher than that of the host material. The second hole transport material has a shallow OMO level, but a deeper HOMO level than the first hole transport material. By using this, first, from the first hole transport layer 112-1 to the second hole transport layer 112 A hole is injected into -2. The HOMO of BPAFLP, which is the second hole transport material of the light-emitting element 2. The level is -5.51 eV, and the difference with PCBBiF, the first hole transport material, is 0.15. It is small, eV. Also, the HOMO of αNBA1BP, the second hole transport material of the light-emitting element 3. The level is -5.52 eV, and the difference with PCBBiF, the first hole transport material, is 0.16. The eV is small. Therefore, from the first hole transport layer 112-1 to the second hole transport layer 112-2 Holes are smoothly injected into it.

[0255] Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. Therefore, a barrier of approximately 0.17-0.18 eV exists between the second hole transport material and the host material. It is present. Normally, holes would be injected without any problems, but the difference is that the light-emitting layer 113 contains The HOMO level of the optical material is -5.40 eV, and there is no barrier. Therefore, ultimately, holes are HOMO The holes are preferentially injected into the light-emitting material rather than the static material. When holes are injected directly into the light-emitting material, the above applies. As such, problems such as accelerated degradation and decreased luminous efficiency are likely to occur.

[0256] Therefore, in the light-emitting element 1, which is a light-emitting element according to one aspect of the present invention, the second hole transport layer 112-2 and A third hole transport layer 112-3 is provided between the light-emitting layer 113 and the third hole transport layer 112 The HOMO level of PCzN2, the third hole transport material included in -3, is -5.71 eV. It is located roughly at the same level as the host material (slightly deeper). Therefore, it hinders hole injection into the host material. Without a wall, and given the mixing ratio of the host material and the luminescent material, hole injection into the host material is prioritized. Furthermore, the difference in HOMO levels with the second hole transport material is 0.20 eV and 0.19 eV (effective). (A single digit number, within 0.3 eV), and the positive pressure from the second hole transport material to the third hole transport material. The injection into the hole was also performed without any problems.

[0257] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the light-emitting region is Because the light spreads across the light-emitting layer 113 without concentrating in one area, degradation is not accelerated, and the lifespan is extended. The resulting light-emitting element exhibited excellent luminescence efficiency. [Examples]

[0258] In this embodiment, a light-emitting element 4 according to one aspect of the present invention described in Embodiment 1 will be described. The structural formula of the organic compound used in the light-emitting element 4 is shown below.

[0259] [ka]

[0260] (Method for fabricating the light-emitting element 4) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0261] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0262] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0263] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0264] Next, on the hole injection layer 111, N-(1,1'-bipheny represented by the above structural formula (ii) is injected. Lu-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole- 3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) 20n The first hole transport layer 112-1 is formed by depositing to a thickness of m, and the first hole transport layer 112-1 The above structural formula (x) represents 4,4'-di-(1-naphthyl)-4''- Phenyltriphenylamine (abbreviation: αNBB1BP) is deposited to a film thickness of 5 nm. Then a second hole transport layer 112-2 is formed, and the above structural formula ( iv) 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H -Carbazole (abbreviation: PCPPn) is deposited to a film thickness of 5 nm to transport the third hole. Layer 112-3 was formed.

[0265] Next, the 7-[4-(10-phenyl-9-antryl)f represented by the above structural formula (v) [enyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above composition The formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3- (9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-diamine (Abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCzP A: 25 nm co-deposited to form the light-emitting layer 113 (A: 1,6 mMemFLPAPrn) I did it.

[0266] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0267] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 4 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0268] The element structure of the light-emitting element 4 is summarized in the table below.

[0269] [Table 8]

[0270] The light-emitting element 4 is placed in a glove box under a nitrogen atmosphere, so that the light-emitting element is not exposed to the atmosphere. The process involves sealing with a glass substrate (applying a sealing material around the element and UV treatment during sealing). After heat treatment (at 80°C for 1 hour), the initial characteristics and reliability of these light-emitting elements are determined. The measurements were taken at room temperature (in an atmosphere maintained at 25°C).

[0271] Figure 28 shows the brightness-current density characteristics of the light-emitting element 4, and Figure 29 shows the current efficiency-brightness characteristics. The pressure characteristics are shown in Figure 30, the current-voltage characteristics in Figure 31, and the external quantum efficiency-luminance characteristics in Figure 32. The light spectra are shown in Figure 33. Also, the 1000 cd / m² spectrum of each light-emitting element is also shown. 2 Major in the vicinity The characteristics are shown in Table 8.

[0272] [Table 9]

[0273] From Figures 28 to 33 and Table 6, it can be seen that the light-emitting element 4 is a blue light-emitting element with good characteristics. It was.

[0274] Additionally, the initial brightness is 5000 cd / m². 2 And, with respect to the driving time under the condition of constant current density A graph showing the change in brightness is shown in Figure 34. As shown in Figure 34, the light-emitting element of one aspect of the present invention The child light-emitting element 4 exhibits minimal brightness degradation due to accumulated operating time and is a light-emitting element with a good lifespan. I discovered something.

[0275] In the light-emitting element of this embodiment, the first to third hole transport materials, and the host material The HOMO levels of the luminescent materials are as shown in the table below. The LUMO levels were calculated based on cyclic voltammetry (CV) measurements. Calculation method The procedure is the same as in Example 1.

[0276] [Table 10]

[0277] As shown in the table, in the material used for the light-emitting element 4, the HOMO level of the second hole transport material is The HOMO level of the host material is deeper than the HOMO level of the first hole transport material, and the HOMO level of the host material is deeper than the HOMO level of the second hole. The HOMO level of the third hole transport material is deeper than the HOMO level of the host material. It is deeper than the HOMO level. Also, the HOMO level of the luminescent material is deeper than the HOMO level of the host material. It's also shallow.

[0278] The HOMO level of PCBBiF, the first hole transport material, is shallow at -5.36 eV, and HAT-C It can interact with the LUMO level of N at -4.41 eV, easily causing charge separation.

[0279] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and P There is a 0.33 eV difference in the HOMO level of CBBiF. On the other hand, the luminescent material 1,6 Since the HOMO level of mMemFLPAPrn is -5.40 eV, the difference is 0.04 It is eV. Since the difference in HOMO levels between the light-emitting material and the first hole transport material is small, A light-emitting element having a structure in which a hole transport layer 112-1 and a light-emitting layer 113 are in contact. When considering the possibility of a child, hole injection into the light-emitting material is likely to occur. However, direct emission When holes are injected into the light material, the holes are transported by the light-emitting material through the first hole transport layer 112-1 and emit light. The light-emitting region may become trapped at the layer interface, potentially accelerating degradation. The hole transport material in the hole transport layer 112-1 has difficulty entering the host material of the light-emitting layer. Therefore, holes accumulate in the hole transport material and electrons accumulate in the host material. Excyplexes, which have lower energy than luminescent materials, are found between hole transport materials and host materials. This can lead to the formation of a luminescence barrier, which can result in problems such as reduced luminescence efficiency.

[0280] In the light-emitting element 4, the second hole transport layer 112-2 has a shallower HOMO level than the host material. The formation is carried out using a second hole transport material whose HOMO level is deeper than that of the first hole transport material. First, holes are transported from the first hole transport layer 112-1 to the second hole transport layer 112-2. Inject the following: The HOMO level of the second hole transport material, αNBB1BP, is -5.50 eV. Therefore, the difference with PCBBiF, the first hole transport material, is small at 0.14 eV. Therefore, holes are smoothly transported from the first hole transport layer 112-1 to the second hole transport layer 112-2. It is injected.

[0281] Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. Therefore, a barrier of approximately 0.19 eV exists between the second hole transport material and the host material. Normally, holes would be injected without any problems, but the difference is that the H of the light-emitting material contained in the light-emitting layer 113 The OMO level is -5.40 eV, and holes are injected from the second hole transport material into the light-emitting material. There are no barriers to this. Therefore, holes are ultimately preferentially directed towards the light-emitting material rather than the host material. It gets injected. When holes are injected directly into the light-emitting material, degradation is accelerated as described above. This can easily lead to problems such as reduced light efficiency.

[0282] Therefore, in the light-emitting element 4, which is a light-emitting element according to one aspect of the present invention, the second hole transport layer 112-2 and A third hole transport layer 112-3 is provided between the light-emitting layer 113 and the third hole transport layer 112 The HOMO level of PCPPn, the third hole transport material included in -3, is -5.80 eV. It is located deeper than the host material. Therefore, there is no barrier to hole injection into the host material. The mixing ratio of the host material and the light-emitting material also prioritizes the injection of holes into the host material. The difference in HOMO levels between this material and the hole transport material is 0.30 eV (within 0.3 eV to one significant figure). Therefore, the injection of holes from the second hole transport material to the third hole transport material is also performed without any problems. .

[0283] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the luminescence region Because the light is spread across the light-emitting layer 113 without concentrating in one area, degradation is not accelerated and the lifespan is extended. This resulted in a light-emitting element with good luminescence efficiency. [Examples]

[0284] In this embodiment, a light-emitting element 5 according to one aspect of the present invention described in Embodiment 1 will be described. The structural formula of the organic compound used in the light-emitting element 5 is shown below.

[0285] [ka]

[0286] (Method for fabricating the light-emitting element 5) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0287] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0288] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0289] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0290] Next, on the hole injection layer 111, 9,9-dimethyl-N-F, represented by the above structural formula (xi), is injected. Phenyl-N-[4-(9-phenyl-9H-carbazole-3-yl)phenyl]-Fur Oren-2-amine (abbreviated as PCBAF) is deposited to a film thickness of 20 nm to form the first A hole transport layer 112-1 is formed, and the above structural formula (iii) is placed on the first hole transport layer 112-1. 4-(1-naphthyl)-4'-phenyltriphenylamine (abbreviated as αNBA) is represented by 4-(1-naphthyl)-4'-phenyltriphenylamine. 1BP) is deposited to a thickness of 5 nm to form a second hole transport layer 112-2, and the second On the hole transport layer 112-2, the 3-[4-(9-phenant represented by the above structural formula (iv) (Lyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn) film thickness 5 A third hole transport layer 112-3 was formed by depositing material to a size of nm.

[0291] Next, the 7-[4-(10-phenyl-9-antryl) represented by the above structural formula (v) Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above The structural formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3 -(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine n (abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCz) The light-emitting layer 113 is co-deposited at a 25 nm thickness so that PA:1,6mMemFLPAPrn) It was formed.

[0292] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0293] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 5 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0294] The element structure of the light-emitting element 5 is summarized in the table below.

[0295] [Table 11]

[0296] The light-emitting element 5 is placed in a glove box under a nitrogen atmosphere, so that the light-emitting element is not exposed to the atmosphere. The process involves sealing with a glass substrate (applying a sealing material around the element and UV treatment during sealing). After heat treatment (at 80°C for 1 hour), the initial characteristics and reliability of these light-emitting elements are determined. The measurements were taken at room temperature (in an atmosphere maintained at 25°C).

[0297] Figure 35 shows the brightness-current density characteristics of the light-emitting element 5, and Figure 36 shows the current efficiency-brightness characteristics. Voltage characteristics are shown in Figure 37, current-voltage characteristics in Figure 38, and external quantum efficiency-luminance characteristics in Figure 39. The emission spectra of each light-emitting element are shown in Figure 40. 2 Main in the vicinity The key characteristics are shown in Table 12.

[0298] [Table 12]

[0299] From Figures 35 to 40 and Table 8, it can be seen that the light-emitting element 5 is a blue light-emitting element with good characteristics. It was.

[0300] Additionally, the initial brightness is 5000 cd / m². 2 And, with respect to the driving time under the condition of constant current density A graph showing the change in brightness is shown in Figure 41. As shown in Figure 41, the light-emitting element of one aspect of the present invention The child light-emitting element 5 exhibits minimal brightness degradation due to accumulated operating time and is a light-emitting element with a good lifespan. I discovered something.

[0301] In the light-emitting element of this embodiment, the first to third hole transport materials, and the host material The HOMO levels of the luminescent materials are as shown in the table below. The LUMO levels were calculated based on cyclic voltammetry (CV) measurements. Calculation method The procedure is the same as in Example 1.

[0302] [Table 13]

[0303] As shown in the table, in the material used for the light-emitting element 5, the HOMO level of the second hole transport material is The HOMO level of the host material is deeper than the HOMO level of the first hole transport material, and the HOMO level of the host material is deeper than the HOMO level of the second hole. The HOMO level of the third hole transport material is deeper than the HOMO level of the host material. It is deeper than the HOMO level. Also, the HOMO level of the luminescent material is deeper than the HOMO level of the host material. It's also shallow.

[0304] The HOMO level of PCBAF, the first hole transport material, is shallow at -5.38 eV, and HAT-CN It can interact with the LUMO level of -4.41 eV to easily induce charge separation.

[0305] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and P There is a difference of 0.31 eV from the HOMO level of CBAF. On the other hand, the luminescent material is 1,6m Since the HOMO level of MemFLPAPrn is -5.40eV, the difference is 0.02eV. It is V. Since the difference in HOMO levels between the luminescent material and the first hole transport material is small, the first A light-emitting element having a structure in which a hole transport layer 112-1 and a light-emitting layer 113 are in contact. In this scenario, hole injection into the light-emitting material is likely to occur. However, direct light emission... When holes are injected into the material, the holes are transported by the light-emitting material to the first hole transport layer 112-1 and the light-emitting layer It may get trapped at the interface, causing the light-emitting region to concentrate and potentially accelerating degradation. Also, the first Is it because holes are difficult to enter the host material of the light-emitting layer from the hole transport material of the hole transport layer 112-1? Then, holes accumulate in the hole transport material and electrons accumulate in the host material. A lower energy excyplex than that of the light-emitting material is created between the pore transport material and the host material. This can lead to problems such as the formation of luminescence, which can result in reduced luminescence efficiency.

[0306] In the light-emitting element 5, the second hole transport layer 112-2 has a shallower HOMO level than the host material. The formation is carried out using a second hole transport material whose HOMO level is deeper than that of the first hole transport material. First, holes are transported from the first hole transport layer 112-1 to the second hole transport layer 112-2. Inject the second hole transport material, αNBA1BP, whose HOMO level is -5.52 eV. Therefore, the difference with PCBAF, the first hole transport material, is small at 0.14 eV. Holes are smoothly transported from the first hole transport layer 112-1 to the second hole transport layer 112-2. To be admitted.

[0307] Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. Therefore, there is a distance of approximately 0.17 eV between the second hole transport material, αNBA1BP, and the host material. A barrier exists. Normally, holes would be injected without any problems, but in the light-emitting layer 113... The HOMO level of the included luminescent material is -5.40 eV, and light is emitted from the second hole transport material. There are no barriers to injecting holes into the material. Therefore, holes are more likely to penetrate the light-emitting material than the host material. The holes are preferentially injected into the material. If holes are injected directly into the light-emitting material, degradation is accelerated as described above. This can easily lead to problems such as reduced light output and decreased luminous efficiency.

[0308] Therefore, in the light-emitting element 5, which is a light-emitting element according to one aspect of the present invention, the second hole transport layer 112-2 and A third hole transport layer 112-3 is provided between the light-emitting layer 113 and the third hole transport layer 112 The HOMO level of PCPPn, the third hole transport material included in -3, is -5.80 eV. It is located deeper than the host material. Therefore, there is no barrier to hole injection into the host material. The mixing ratio of the host material and the light-emitting material also prioritizes the injection of holes into the host material. The difference in HOMO levels between this material and the hole transport material is 0.27 eV (within 0.3 eV to one significant figure). Therefore, the injection of holes from the second hole transport material to the third hole transport material is also performed without any problems. .

[0309] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the emission region Because the light distribution is spread across the light-emitting layer 113 rather than being concentrated in one area, degradation is not accelerated and the lifespan is not extended. As a result, it became a light-emitting element with good luminescence efficiency. [Examples]

[0310] In this embodiment, the light-emitting element 6, light-emitting element 7 and the light-emitting element according to one aspect of the present invention described in Embodiment 1 Let's explain the optical element 8. The structural formula of the organic compound used in the light-emitting element 8 is shown below, from the light-emitting element 6. See below.

[0311] [ka]

[0312] (Method for fabricating the light-emitting element 6) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0313] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0314] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0315] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0316] Next, on the hole injection layer 111, N-(1,1'-bipheny represented by the above structural formula (ii) is injected. Lu-4-yl)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole- 3-yl)phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) 20n The first hole transport layer 112-1 is formed by depositing to a thickness of m, and the first hole transport layer 112-1 shows 4-(10-phenyl-9-anthryl, represented by the above structural formula (xii) above. )-4'-(9-phenyl-9H-fluoren-9-yl)triphenylamine (abbreviation: FLPAPA) is deposited to a thickness of 5 nm to form a second hole transport layer 112-2. On the second hole transport layer 112-2, 3-[4-(9-Fe represented by the above structural formula (iv) is present. Nanthril)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn) A third hole transport layer 112-3 was formed by depositing a film thickness of 5 nm.

[0317] Next, the 7-[4-(10-phenyl-9-antryl) represented by the above structural formula (v) Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above The structural formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3 -(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine n (abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCz) The light-emitting layer 113 is co-deposited at a 25 nm thickness so that PA:1,6mMemFLPAPrn) It was formed.

[0318] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0319] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 6 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0320] (Method for fabricating the light-emitting element 7) The light-emitting element 7 is represented by the above structural formula (xiii) as the material for the second hole transport layer 112-2. 9,9-bis[(N,N-bis-biphenyl-4-yl-amino)phenyl]-9 Aside from using H-fluorene (abbreviated as BPAPF), the device was fabricated in the same manner as light-emitting element 6.

[0321] (Method for fabricating the light-emitting element 8) The light-emitting element 8 is represented by the above structural formula (xiv) as the material for the second hole transport layer 112-2. , 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA) Aside from using [specific material], it was fabricated in the same manner as the light-emitting element 6.

[0322] The element structures of light-emitting elements 6, 7, and 8 are summarized in the table below.

[0323] [Table 14]

[0324] The light-emitting elements 6 to 8 are placed in a glove box in a nitrogen atmosphere, and the light-emitting elements are large The process of sealing the element with a glass substrate to prevent exposure to the elements (applying a sealing material around the element, After UV treatment and heat treatment at 80°C for 1 hour during sealing, the initial characteristics of these light-emitting elements are determined. Reliability measurements were performed. The measurements were conducted at room temperature (in an atmosphere maintained at 25°C). .

[0325] Figure 42 shows the brightness-current density characteristics of light-emitting elements 6 to 8, and the current efficiency-brightness characteristics. Figure 43 shows the luminance-voltage characteristics, Figure 44 shows the current-voltage characteristics, and Figure 45 shows the external quantum efficiency-luminance characteristics. The properties are shown in Figure 46, and the emission spectra are shown in Figure 47. The emission spectrum of each light-emitting element is 1000 cd / m². 2 Table 15 shows the main characteristics of the vicinity.

[0326] [Table 15]

[0327] From Figures 42 to 47 and Table 15, it can be seen that light-emitting elements 6 to 8 are blue light-emitting elements with good characteristics. It turned out to be a child.

[0328] Additionally, the initial brightness is 5000 cd / m². 2 Assuming a constant current density, the driving time is as follows: A graph showing the change in brightness is shown in Figure 48. As shown in Figure 48, a light-emitting element according to one aspect of the present invention The light-emitting elements 6 to 8 exhibit little decrease in brightness due to the accumulation of operating time and have a good lifespan. It was found to be a light-emitting element.

[0329] In the light-emitting element of this embodiment, the first to third hole transport materials, and the host material The HOMO levels of the luminescent materials are as shown in the table below. The LUMO levels were calculated based on cyclic voltammetry (CV) measurements. Calculation method The procedure is the same as in Example 1.

[0330] [Table 16]

[0331] [Table 17]

[0332] [Table 18]

[0333] As shown in the table, in the materials used in the light-emitting elements 6 to 8, the second hole transport material The HOMO level is deeper than the HOMO level of the first hole transport material, and the HOMO level of the host material The level is deeper than the HOMO level of the second hole transport material, and the HOMO level of the third hole transport material. The HOMO level of the luminescent material is deeper than that of the host material. It is shallower than the HOMO level.

[0334] The HOMO level of PCBBiF, the first hole transport material, is shallow at -5.36 eV, and HAT-C It can interact with the LUMO level of N at -4.41 eV, easily causing charge separation.

[0335] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and P There is a 0.33 eV difference in the HOMO level of CBBiF. On the other hand, the luminescent material 1,6 Since the HOMO level of mMemFLPAPrn is -5.40 eV, the difference is 0.04 It is eV. Since the difference in HOMO levels between the light-emitting material and the first hole transport material is small, A light-emitting element having a structure in which a hole transport layer 112-1 and a light-emitting layer 113 are in contact. When considering the possibility of a child, hole injection into the light-emitting material is likely to occur. However, direct emission When holes are injected into the light material, the holes are transported by the light-emitting material through the first hole transport layer 112-1 and emit light. The light-emitting region may become trapped at the layer interface, potentially accelerating degradation. The hole transport material in the hole transport layer 112-1 has difficulty entering the host material of the light-emitting layer. Therefore, holes accumulate in the hole transport material and electrons accumulate in the host material. Excyplexes, which have lower energy than luminescent materials, are found between hole transport materials and host materials. This can lead to the formation of a luminescence barrier, which can result in problems such as reduced luminescence efficiency.

[0336] In light-emitting elements 6 to 8, the second hole transport layer 112-2 is made of HOM material rather than the host material. A second hole transport material is used, which has a shallow O level but a deeper HOMO level than the first hole transport material. By forming the first hole transport layer 112-1, the second hole transport layer 1 A hole is injected into 12-2. The second hole transport material is FLPAPA (light-emitting element 6), B The HOMO levels of PAPF (light-emitting element 7) and DPhPA (light-emitting element 8) are -5.54e, respectively. The values ​​are V, -5.50eV, and -5.53eV, and PCBBiF is the first hole transport material. The differences are small, 0.18eV, 0.14eV, and 0.17eV respectively. Therefore, the first Holes are smoothly injected from the hole transport layer 112-1 to the second hole transport layer 112-2. .

[0337] Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. And between the second hole transport material and the host material, there are 0.15 eV and 0.19 eV, respectively. There is a barrier of about 0.16 eV. Normally, this difference would allow holes to be injected without any problems. The HOMO level of the light-emitting material contained in the light-emitting layer 113 is -5.40 eV, and the second hole There is no barrier to inject holes from the transport material to the light-emitting material. Therefore, the holes ultimately... The holes are preferentially injected into the light-emitting material rather than the host material. As a result, as mentioned above, problems such as accelerated degradation and decreased luminous efficiency are likely to occur. stomach.

[0338] Therefore, in the light-emitting elements 6 to 8, which are light-emitting elements according to one aspect of the present invention, the second hole transport A third hole transport layer 112-3 was provided between layer 112-2 and the light-emitting layer 113. The HOMO state of PCPPn, the third hole transport material contained in hole transport layer 112-3 of 3. The location is -5.80 eV, which is deeper than the host material. Therefore, the hole in the host material There are no barriers to injection, and the mixing ratio of the host material and the luminescent material also favors hole injection into the host material. It is preceded by the second hole transport material. Furthermore, the difference in HOMO levels with the second hole transport material is from 0.26 eV to 0.30 eV. eV (within 0.3 eV to one significant digit), and the third hole transport from the second hole transport material. Hole injection into the material is also performed without any problems.

[0339] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the emission region Because the light emission area is spread across the light-emitting layer 113 without being concentrated in one area, degradation is not accelerated and light emission is not accelerated. Elements 6 through 8 have been made into light-emitting elements with good lifespan and luminous efficiency. [Examples]

[0340] In this embodiment, the light-emitting element 9, light-emitting element 10 and the light-emitting element 10 of the present invention described in Embodiment 1 are shown. The light-emitting element 11 will be described. The structure of the organic compound used in light-emitting elements 9 through 11. The formula is shown below.

[0341] [ka]

[0342] (Method for fabricating the light-emitting element 9) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0343] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0344] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0345] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0346] Next, on the hole injection layer 111, 4,4'-bis[N-(1 -Naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) is used to a film thickness of 10 nm. A first hole transport layer 112-1 is formed by deposition, and on the first hole transport layer 112-1 The above structural formula (xvi) represents 4-(2-naphthyl)-4',4”-diphenyltri Phenylamine (abbreviated as BBAβNB) is deposited to a thickness of 10 nm to create a second hole. A transport layer 112-2 is formed, and the above structural formula (xvii) is used on the second hole transport layer 112-2. The expressed 3,6-bis[4-(2-naphthyl)phenyl]-9-phenyl-9H-carb A third hole transport layer 1 is formed by depositing zole (abbreviated as βNP2PC) to a thickness of 10 nm. A 12-3 formation was created.

[0347] Next, the 7-[4-(10-phenyl-9-antryl) represented by the above structural formula (v) Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above The structural formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3 -(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine n (abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCz) The light-emitting layer 113 is co-deposited at a 25 nm thickness so that PA:1,6mMemFLPAPrn) It was formed.

[0348] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0349] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 9 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0350] (Method for fabricating the light-emitting element 10) The light-emitting element 10 uses BBA as the material for the second hole transport layer 112-2 in the light-emitting element 9. 4-(1-naphthyl)-4',4, represented by the above structural formula (xviii) instead of βNB. Apart from the use of -diphenyltriphenylamine (abbreviation: BBAαNB), the light-emitting element 9 and It was made in the same way.

[0351] (Method for fabricating the light-emitting element 11) The light-emitting element 11 uses BBA as the material for the second hole transport layer 112-2 in the light-emitting element 9. Instead of βNB, 4-[4-(2-naphthyl)phenyl, represented by the above structural formula (xix), is used. Other than using ]-4',4"-diphenyltriphenylamine (abbreviation: BBAβNBi), It was fabricated in the same way as the light-emitting element 9.

[0352] The element structures of light-emitting elements 9 to 11 are summarized in the table below.

[0353] [Table 19]

[0354] The light-emitting elements 9 to 11 are placed in a glove box in a nitrogen atmosphere, and the light-emitting elements The process of sealing the element with a glass substrate to prevent exposure to the atmosphere (applying a sealing material around the element) After UV treatment and heat treatment at 80°C for 1 hour during sealing, the initial characteristics of these light-emitting elements are determined. The reliability was also measured. The measurements were taken at room temperature (in an atmosphere maintained at 25°C). Ta.

[0355] Figure 49 shows the luminance-current density characteristics of light-emitting elements 9 to 11, and the current efficiency-luminance characteristics. Figure 50 shows the luminance-voltage characteristics, Figure 51 shows the current-voltage characteristics, and Figure 52 shows the external quantum efficiency-luminance characteristics. The characteristics are shown in Figure 53, and the emission spectra are shown in Figure 54. The emission spectrum for each light-emitting element is 1000 cd / m². 2Table 20 shows the main characteristics of the vicinity.

[0356] [Table 20]

[0357] From Figures 49 to 54 and Table 20, light-emitting elements 9 to 11 exhibit good blue light emission characteristics. It was found to be an element.

[0358] Furthermore, assuming a current value of 2mA, the change in brightness with respect to the operating time under the condition of constant current density is... The graph illustrating this is shown in Figure 55. As shown in Figure 55, the light-emitting element is a light-emitting element according to one aspect of the present invention. Sub-elements 9 through 11 exhibit little decrease in brightness due to accumulated operating time and have a good lifespan. It was found that...

[0359] In the light-emitting element of this embodiment, the first to third hole transport materials, and the host material The HOMO levels of the luminescent materials are as shown in the table below. The LUMO levels were calculated based on cyclic voltammetry (CV) measurements. Calculation method The procedure is the same as in Example 1.

[0360] [Table 21]

[0361] [Table 22]

[0362] [Table 23]

[0363] As shown in the table, in the materials used in the light-emitting elements 9 to 11, the second hole transport material The HOMO level of the first hole transport material is deeper than the HOMO level of the host material. The level is deeper than the HOMO level of the second hole transport material, and the HOMO level of the third hole transport material The level is deeper than the HOMO level of the host material. Also, the HOMO level of the luminescent material is deeper than that of the host material. It is shallower than the HOMO level.

[0364] The HOMO level of the first hole transport material, NPB, is shallow at -5.38 eV, and the L of HAT-CN It can interact with the UMO level -4.41eV to easily induce charge separation.

[0365] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and N There is a 0.31 eV difference in the HOMO level of PB. On the other hand, the luminescent material is 1,6 mME. Since the HOMO level of mFLPAPrn is -5.40 eV, the difference is 0.02 eV. Yes. Because the difference in HOMO levels between the luminescent material and the first hole transport material is small, the first hole transport material Imagine a light-emitting element having a structure in which a pore transport layer 112-1 and a light-emitting layer 113 are in contact. If the conditions are met, hole injection into the light-emitting material is likely to occur. However, direct light-emitting material When a hole is injected, the hole is directed by the light-emitting material between the first hole transport layer 112-1 and the light-emitting layer. The light is trapped across the surface, and the luminescent area may become concentrated, potentially accelerating degradation. Also, the first hole Because it is difficult for holes to enter the host material of the light-emitting layer from the hole transport material of transport layer 112-1, Holes accumulate in the hole transport material, and electrons accumulate in the host material. Then, the hole transport An excyplex with lower energy than the light-emitting material is formed between the transport material and the host material. This can lead to problems such as a decrease in luminous efficiency.

[0366] In light-emitting elements 9 to 11, the second hole transport layer 112-2 is made of HO material, which is more HO than the host material. A second hole transport material is used, which has a shallow MO level but a deeper HOMO level than the first hole transport material. By forming the first hole transport layer 112-1, the second hole transport layer 1 A hole is injected into 12-2. The second hole transport material is BBAβNB (light-emitting element 9), B The HOMO levels of BAαNB (light-emitting element 10) and BBAβNBi (light-emitting element 11) are respectively - The values ​​are 5.47eV, -5.49eV, and -5.47eV, and it is the first hole transport material, NP The differences with B are small, at 0.09eV, 0.11eV, and 0.09eV respectively. Therefore, Holes are smoothly injected from the first hole transport layer 112-1 to the second hole transport layer 112-2. It can be done.

[0367] Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. And between the second hole transport material and the host material, there are 0.22 eV and 0.20 eV, respectively. A barrier of approximately 0.22 eV exists. Normally, this difference would allow holes to be injected without issue, but... The HOMO level of the light-emitting material contained in the light-emitting layer 113 is -5.40 eV, and the second hole There is no barrier to inject holes from the transport material to the light-emitting material. Therefore, the holes ultimately... The holes are preferentially injected into the light-emitting material rather than the host material. As a result, as mentioned above, problems such as accelerated degradation and decreased luminous efficiency are likely to occur. stomach.

[0368] Therefore, in the light-emitting elements 9 to 11, which are light-emitting elements according to one aspect of the present invention, the second hole channel A third hole transport layer 112-3 is provided between the transport layer 112-2 and the light-emitting layer 113. The HOM of βNP2PC, the third hole transport material contained in the third hole transport layer 112-3 The O level is located at -5.79 eV, deeper than the host material. Therefore, a second hole transport occurs. Holes are successfully injected from the material to the third hole transport material, and also into the host material. There are no barriers, and the mixing ratio of the host material and the light-emitting material prioritizes hole injection into the host material. Furthermore, the difference in HOMO levels with the second hole transport material is 0.30 eV to 0.32 eV. (Within 0.3 eV to one significant digit), from the second hole transport material to the third hole transport material The holes are injected without any problems.

[0369] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the emission region Because the light emission area is spread across the light-emitting layer 113 without being concentrated in one area, degradation is not accelerated and light emission is not accelerated. The elements 9 through 11 became light-emitting elements with good lifespan and luminous efficiency. [Examples]

[0370] In this embodiment, a light-emitting element 12 according to one aspect of the present invention described in Embodiment 1 will be described. The structural formula of the organic compound used in the light-emitting element 12 is shown below. [ka]

[0371] (Method for fabricating the light-emitting element 12) First, indium tin oxide (ITSO) containing silicon oxide is sputtered onto a glass substrate. The first electrode 101 was formed by depositing a film using the 3D method. The film thickness was set to 110 nm. The area was set to 2mm x 2mm.

[0372] Next, as a pretreatment for forming light-emitting elements on the substrate, the substrate surface is washed with water, and 200 After firing at ℃ for 1 hour, UV ozone treatment was performed for 370 seconds.

[0373] Then, 10 -4 A substrate is introduced into a vacuum deposition apparatus where the internal pressure is reduced to approximately Pa, and then vacuum deposition is performed. After vacuum firing at 170°C for 30 minutes in the heating chamber of the apparatus, the substrate is left for approximately 30 minutes. It was allowed to cool.

[0374] Next, the first electrode 101 is formed such that the surface on which the first electrode 101 is formed faces downwards. The prepared substrate is fixed to a substrate holder provided inside the vacuum deposition apparatus, and on the first electrode 101, By vapor deposition using resistance heating, 2,3,6,7,10,11 represented by the above structural formula (i) are obtained. -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT) A hole injection layer 111 was formed by depositing -CN) at a 5nm layer.

[0375] Next, on the hole injection layer 111, 4,4'-bis[N-(1 -Naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) is used to a film thickness of 10 nm. A first hole transport layer 112-1 is formed by deposition, and on the first hole transport layer 112-1 The above structural formula (xvi) represents 4-(2-naphthyl)-4',4”-diphenyltri Phenylamine (abbreviated as BBAβNB) is deposited to a thickness of 10 nm to create a second hole. A transport layer 112-2 is formed, and the structure represented by the above structural formula (xx) is placed on the second hole transport layer 112-2. 3-[4-(2-naphthyl)phenyl]-9-(2-naphthyl)-9H-carbazole A layer (abbreviated as βNPβNC) is deposited to a thickness of 10 nm to form the third hole transport layer 112 -3 was formed.

[0376] Next, the 7-[4-(10-phenyl-9-antryl) represented by the above structural formula (v) Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) and the above The structural formula (vi) represents N,N'-bis(3-methylphenyl)-N,N'-bis[3 -(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine n (abbreviation: 1,6mMemFLPAPrn) and a weight ratio of 1:0.03 (=cgDBCz) The light-emitting layer 113 is co-deposited at a 25 nm thickness so that PA:1,6mMemFLPAPrn) It was formed.

[0377] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 10 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (vii), is used in a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0378] After forming the electron transport layer 114, lithium fluoride (LiF) is vapor-deposited to a thickness of 1 nm. Then, an electron injection layer 115 is formed, and subsequently, aluminum is applied to a thickness of 200 nm. The light-emitting element 12 of this embodiment was fabricated by forming a second electrode 102 through vapor deposition.

[0379] The element structure of the light-emitting element 12 is summarized in the table below.

[0380] [Table 24]

[0381] The light-emitting element 12 is placed in a glove box under a nitrogen atmosphere, so that the light-emitting element is not exposed to the atmosphere. The process involves sealing the element with a glass substrate (applying a sealing material around the element and using UV light during sealing). After processing (heat treatment at 80°C for 1 hour), the initial characteristics and reliability of these light-emitting elements are determined. The measurements were taken at room temperature (maintained at 25°C).

[0382] Figure 56 shows the brightness-current density characteristics of the light-emitting element 12, and Figure 57 shows the current efficiency-brightness characteristics. -Voltage characteristics are shown in Figure 58, current-voltage characteristics in Figure 59, and external quantum efficiency-luminance characteristics in Figure 60. The emission spectra of each light-emitting element are shown in Figure 61. 2 in the vicinity The main characteristics are shown in Table 25.

[0383] [Table 25]

[0384] From Figures 56 to 61 and Table 25, the light-emitting element 12 is a blue light-emitting element with good characteristics. I found out.

[0385] Furthermore, assuming a current value of 2mA, the change in brightness with respect to the operating time under the condition of constant current density is... The graph illustrating this is shown in Figure 62. As shown in Figure 62, the light-emitting element is a light-emitting element according to one aspect of the present invention. Child 12 exhibited minimal brightness degradation with accumulated operating time, indicating that it is a light-emitting element with a good lifespan. It was.

[0386] In the light-emitting element 12 of this embodiment, the first hole transport material to the third hole transport material, host The HOMO levels of the material and the luminescent material are as shown in the table below. The lumens level and LUMO level were calculated based on cyclic voltammetry (CV) measurements. The method of extraction is the same as in Example 1.

[0387] [Table 26]

[0388] As shown in the table, in the material used for the light-emitting element 12, the HOMO level of the second hole transport material The HOMO level of the first hole transport material is deeper than the HOMO level of the second hole transport material. The HOMO level of the third hole transport material is deeper than the HOMO level of the host material. It is deeper than the HOMO level of the host material. Also, the HOMO level of the luminescent material is deeper than the HOMO level of the host material. It is shallower than that.

[0389] The HOMO level of the first hole transport material, NPB, is shallow at -5.38 eV, and the L of HAT-CN It can interact with the UMO level -4.41eV to easily induce charge separation.

[0390] Here, the HOMO level of the host material cgDBCzPA is -5.69 eV, and N There is a 0.31 eV difference in the HOMO level of PB. On the other hand, the luminescent material is 1,6 mME. Since the HOMO level of mFLPAPrn is -5.40 eV, the difference is 0.02 eV. Yes. Because the difference in HOMO levels between the luminescent material and the first hole transport material is small, the first hole transport material Imagine a light-emitting element having a structure in which a pore transport layer 112-1 and a light-emitting layer 113 are in contact. If the conditions are met, hole injection into the light-emitting material is likely to occur. However, direct light-emitting material When a hole is injected, the hole is directed by the light-emitting material between the first hole transport layer 112-1 and the light-emitting layer. The light is trapped across the surface, and the luminescent area may become concentrated, potentially accelerating degradation. Also, the first hole Because it is difficult for holes to enter the host material of the light-emitting layer from the hole transport material of transport layer 112-1, Holes accumulate in the hole transport material, and electrons accumulate in the host material. Then, the hole transport An excyplex with lower energy than the light-emitting material is formed between the transport material and the host material. This can lead to problems such as a decrease in luminous efficiency.

[0391] In the light-emitting element 12, the second hole transport layer 112-2 has a shallower HOMO level than the host material. This is achieved by using a second hole transport material, which has a deeper HOMO level than the first hole transport material. First, holes are transported from the first hole transport layer 112-1 to the second hole transport layer 112-2. Inject the following. The HOMO levels of the second hole transport material, BBAβNB, are -5.47e each. The difference between V and the first hole transport material, NPB, is a small 0.09 eV. Therefore, the transfer from the first hole transport layer 112-1 to the second hole transport layer 112-2 is smooth. The hole is filled.

[0392] Here, we consider a light-emitting element having a structure in which the second hole transport layer 112-2 and the light-emitting layer 113 are in contact. Now, let's consider the case where holes are injected from the second hole transport layer 112-2 to the light-emitting layer 113. A barrier of approximately 0.22 eV exists between the second hole transport material and the host material. Normally, holes would be injected without any problems, but the light-emitting material contained in the light-emitting layer 113 The HOMO level of the material is -5.40 eV, and holes are injected from the second hole transport material to the light-emitting material. There are no barriers to entry. Therefore, holes ultimately have priority over host materials in the light-emitting material. They are injected directly into the material. When holes are injected directly into the light-emitting material, degradation is accelerated as described above. Problems such as reduced light output and decreased luminous efficiency are likely to occur.

[0393] Therefore, in the light-emitting element 12, which is a light-emitting element according to one aspect of the present invention, the second hole transport layer 112-2 A third hole transport layer 112-3 is provided between the light-emitting layer 113 and the third hole transport layer 112-3. The HOMO level of βNPβNC, the third hole transport material contained in layer 112-3, is -5. It is located at a depth of 77 eV, deeper than the host material. Therefore, from the second hole transport material, the third Holes are injected into the hole transport material without any problems. Also, holes are injected from the third hole transport material into the host material. Since there are no barriers to hole injection into the host material, the mixing ratio of the host material and the light-emitting material also affects the hole injection into the host material. Since hole injection is prioritized, holes are rarely injected directly into the light-emitting material. The difference in HOMO levels between the second hole transport material and the third hole transport material is 0.30 eV. The effective value is within 0.3 eV (within a single digit), and the transfer from the second hole transport material to the third hole transport material is The holes are injected without any problems.

[0394] Some of the holes injected into the host material are trapped in the light-emitting material, but an appropriate amount of hole trapping is required. In addition to being able to move towards the second electrode while receiving, the host material also possesses electron transport properties. Because it is an anthracene compound, the driving voltage does not increase. Also, the emission region Because the light emission area is spread across the light-emitting layer 113 without being concentrated in one area, degradation is not accelerated and light emission is not accelerated. Element 12 became a light-emitting element with good lifespan and luminous efficiency.

[0395] (Reference example 1) In this reference example, the 4-naphthyl-4',4''- used in the light-emitting element 9 and light-emitting element 12 described above This section describes the synthesis method of diphenyltriphenylamine (abbreviation: BBAβNB). The structural formula of BAβNB is shown below.

[0396] [ka]

[0397] In a 200 mL three-necked flask, add 2.3 g (7.1 mmol) of bis(4-biphenylyl) Min, 2.0 g (7.1 mmol) of 2-(4-bromophenyl)naphthalene, and 1. 5 g (15 mmol) of sodium tert-butoxide (abbreviation: tert-BuON a) and 2-dicyclohexylphosphino-2'-6'-dimethoxy-1,1'-bife Add Sphos (abbreviated as Nyl), purge the flask with nitrogen, then add 35 mL of xylene. It was added. After degassing this mixture under reduced pressure, it was stirred at 60°C under a nitrogen stream, and 0.12 Add g (0.20 mmol) of bis(dibenzylideneacetone)palladium(0), This mixture was stirred at 120°C for 7 hours. After stirring, the resulting mixture was washed with water and saturated saline solution. The organic layer was purified and washed with magnesium sulfate. The magnesium sulfate was removed by natural filtration. Afterward, the obtained filtrate was concentrated to obtain a brown solid, which was then subjected to high-performance liquid chromatography (mobile phase chromatograph). Purification with lolloform yielded 3.5 g of the target substance as a pale yellow solid in 93% yield. The synthesis scheme for this reaction is shown below.

[0398] [ka]

[0399] The white individuals obtained 1 The 1H NMR spectrum is shown below. 1 1H NMR (dichloromethane - d2, 500MHz): δ=7.24 (d, J=9.0) Hz, 4H), 7.26(d, J=8.5Hz, 2H), 7.31(d, J=7.5Hz , 2H), 7.42(d, J=7.5Hz, 4H), 7.45-7.50(m, 2H), 7.55(d, J=8.5Hz, 4H), 7.60(d, J=7.5Hz, 4H), 7. 68(d, J=8.5Hz, 2H), 7.76(dd, J1=2.0Hz, J2=8.5 Hz, 1H), 7.85(d, J=8.0Hz, 1H), 7.90(t, J=8.05H z, 2H), 8.05(s, 1H)

[0400] Also, 1 The H-NMR chart is shown in Figure 63. Note that Figure 63(B) is the same as Figure 63(A). This chart shows an enlarged view of the 7.00 ppm to 8.20 ppm range. It was found that BBAβNB was obtained by this synthesis reaction.

[0401] The obtained 3.5 g of white solid (BBAβNB) was subjected to a train sublimation method. Sublimation purification was performed. The sublimation purification conditions were: pressure 3.4 Pa, argon flow rate 15 mL / min, heating 2 The temperature was set at 65°C for 16 hours. After sublimation purification, 2.8 g of the target substance was obtained as a pale yellow, glassy solid. Recovery rate: I got it at 81%.

[0402] The HOMO and LUMO levels of BBAβNB were analyzed by cyclic voltammetry (CV). The calculation was based on measurements. The calculation method is shown below.

[0403] The measuring device used is an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS model). A 600A or 600C was used for the CV measurement. The solution used for the measurement was anhydrous dimethyl sulfate as the solvent. Aldrich Formamide (DMF) (manufactured by Aldrich Co., Ltd., 99.8%, catalog number; 227) Using 05-6), the supporting electrolyte is tetra-n-butylammonium perchlorate (nB u4NClO4) (manufactured by Tokyo Chemical Co., Ltd., catalog number: T0836) 100 mmol / Dissolve to a concentration of L, and then dissolve the sample to be measured to a concentration of 2 mmol / L. It was prepared by dissolving it. Furthermore, a platinum electrode (manufactured by BAS Corporation, PT) was used as the working electrode. E Platinum electrode) is used as an auxiliary electrode, and platinum electrode (manufactured by B.A.S. Co., Ltd., for VC-3 P A counter electrode (5 cm) is used, and Ag / Ag is used as the reference electrode. + Electrode (B.A.E.) A RE7 non-aqueous solvent reference electrode manufactured by S Corporation was used. The measurements were taken at room temperature (20°C). The measurements were performed at 25°C. The scan speed during CV measurement was standardized to 0.1V / sec. The oxidation potential Ea [V] and reduction potential Ec [V] were measured relative to the irradiated electrode. Ea is the oxidation- The intermediate potential of the reduction wave was used, and Ec was set as the intermediate potential of the reduction-oxidation wave. Here, the values ​​used in this embodiment The potential energy of the reference electrode relative to the vacuum level is -4.94 [eV]. Since it is known that the HOMO level [eV] = -4.94 - Ea, the LUMO level [eV The HOMO level and LUMO level can be determined from the equation ] = -4.94 - Ec. This can be done. Furthermore, the measurement is repeated 100 times, and the oxidation- The electrical stability of the compound was investigated by comparing the reduction wave with the oxidation-reduction wave from the first cycle.

[0404] As a result, it was found that the HOMO level of BBAβNB is -5.47 eV. On the other hand, L The UMO level was found to be -2.28 eV. Furthermore, repeated measurements of the oxidation-reduction wave were performed. When comparing the waveforms at the 1st cycle and after 100 cycles, in the Ea measurement, Since it maintained a peak intensity of 83% and 92% in Ec measurements, BBAβNB is It was confirmed to have excellent resistance to oxidation and reduction.

[0405] Furthermore, differential scanning calorimetry (DSC measurement) of BBAβNB was performed using a PerkinElmer Py Measurements were taken using ris1DSC. Differential scanning calorimetry was performed at a heating rate of 40°C / min. After raising the temperature from -10°C to 300°C, hold it at the same temperature for 1 minute, then cool it down at a rate of 40°C / minute. The cooling operation to -10°C was performed twice consecutively using n. The DSC measurement results from the second cycle are as follows: Furthermore, it was revealed that the glass transition temperature of BBAβNB is 81°C. From the results of the experiment, it was determined that the melting point is 241°C.

[0406] Furthermore, thermogravimetric analysis (TG-DTA) of BBAβNB is performed. We performed a metry-differential thermal analysis. The measurement was performed using a high-vacuum differential thermal balance (Bruker AXS Corporation, TG-D). A TA2410SA was used. The measurement was performed at atmospheric pressure, with a heating rate of 10°C / min, and under nitrogen. The experiment was conducted under airflow conditions (flow rate 200 mL / min). In thermogravimetric analysis-differential thermal analysis, The temperature at which the weight obtained from thermogravimetric analysis becomes -5% of the initial weight (decomposition temperature) is 412°C. This was found to be the case, demonstrating that the material possesses high heat resistance.

[0407] (Reference example 2) In this reference example, the 3,6-bis[4-(2-naphthyl] used in the above-mentioned light-emitting elements 9 to 11 is used in the above-mentioned light-emitting elements 9 to 11. Method for synthesizing phenyl-9-phenyl-9H-carbazole (abbreviation: βNP2PC) This will be explained. The structural formula of βNP2PC is shown below.

[0408] [ka]

[0409] In a 200 mL three-necked flask, add 1.9 g (4.8 mmol) of 3,6-dibromo-9-fe Nyl-9H-carbazole and 2.4 g (9.7 mol) of 4-(2-naphthyl)phenyl Luboronic acid, 0.12g (0.40 mmol) of tri(o-tolyl)phosphine, and 2 0.7g (19 mmol) of potassium carbonate was added. After purging the flask with nitrogen, this To the mixture, 40 mL of toluene, 10 mL of ethanol, and 10 mL of water were added. The mixture was degassed by stirring under reduced pressure. After degassing, 22 mg (0. 10 mmol of palladium(II) acetate was added. This mixture was then subjected to a nitrogen atmosphere at 80°C. After stirring for 4 hours, a solid precipitated. The precipitated solid was recovered by suction filtration. Dissolve the solid in approximately 750 mL of heated toluene, and this solution is mixed with Celite, alumina, and f The sample was filtered by suction through a lorizyl. The resulting filtrate was concentrated, and the obtained solid was washed with toluene. 2.6 g of the target product, a white powder, was obtained in 99% yield. The synthesis scheme for this reaction is shown below. .

[0410] [ka]

[0411] The obtained white powder (2.6 g) was purified by sublimation using the train sublimation method. The conditions were: pressure 3.0 Pa, argon gas flow rate 5.0 mL / min, 350 The white powder was heated at °C. After sublimation purification, 2.0 g of white solid was obtained with a recovery rate of 77%.

[0412] The obtained substance 1 1H NMR was measured. The measurement data is shown below. 1 H NMR(CDCl3,300MHz):δ=7.47-7.55(m,7H),7 .65(s,2H),7.67(d,J=2.4Hz,2H),7.76(dd,J1= 8.4Hz, J2=1.8Hz, 2H), 7.75-7.97(m, 16H), 8.14 (d,J=1.8Hz,2H),8.51(d,J=1.5Hz,2H)

[0413] Also, 1 The H-NMR chart is shown in Figure 64. Note that Figure 64(B) is the same as Figure 64(A). This chart shows an enlarged view of the 7.20 ppm to 8.60 ppm range. It was found that βNP2PC was obtained by this synthesis reaction.

[0414] Furthermore, thermogravimetric analysis (TG-DTA) of βNP2PC is performed. We performed a metry-differential thermal analysis. The measurement was performed using a high-vacuum differential thermal balance (Bruker AXS Corporation, TG-D). A TA2410SA was used. At atmospheric pressure, heating rate 10°C / min, under a nitrogen stream (flow velocity: 20 When measured under conditions of 0 mL / min, the relationship between weight and temperature (thermogravimetric analysis) showed that βNP The temperature at which 2PC lost 5% of its weight was above 500°C. This indicates that βNP2PC has high heat resistance. It has been shown to be of good quality.

[0415] (Reference example 3) In this reference example, the 4-(1-naphthyl)-4',4''-diphenyl used in the light-emitting element 10 This document describes the synthesis method of riphenylamine (abbreviated as BBAαNB). The structural formula is shown below.

[0416] [ka]

[0417] In a 200 mL three-necked flask, add 4.8 g (10 mmol) of 4-bromo-4',4''- Diphenyltriphenylamine and 1.8 g (10 mmol) of 2-naphthylboronic acid , 0.31 g (1.0 mmol) of tris(2-methylphenyl)phosphine and 40 m 1 L of toluene, 10 mL of ethanol, and 10 mL of potassium carbonate aqueous solution (2.0 mL) (1 / L) was added, and the flask was stirred under reduced pressure to degass the mixture. After degassing, the system The mixture was heated to 60°C after being subjected to a nitrogen stream inside. After heating, 0.12g (0.5m Add (mol) palladium(II) acetate and stir the mixture at 80°C for 1.5 hours. After stirring, the mixture was allowed to cool to room temperature, then the organic layer was washed with water, and the resulting aqueous layer was treated with True. Extraction was performed using a saturated saline solution, and the extract solution and organic layer were washed together with saturated saline solution before applying magnesium sulfate. Furthermore, it was dried. This mixture was naturally filtered, and the resulting filtrate was concentrated to obtain the target brown solid. The solid was obtained. The obtained solid was dissolved in chloroform, and this solution was subjected to high-performance liquid chromatography. (Recycled preparative HPLC LC-SakuraNEXT manufactured by Nippon Analytical Industries, mobile phase: When purified with chloroform, 3.9 g of the target substance was obtained as a white solid in a yield of 75%. The synthesis scheme for this reaction is shown below.

[0418] [ka]

[0419] The pale yellow solid obtained 1 1H NMR was measured. The data is shown below. 1 1H NMR (dichloromethane-d2, 500MHz): δ = 7.26-7.29 (m, 6H), 7.31(t, J=7.0Hz, 2H), 7.41-7.54(m, 10H), 7.56(d, J=8.5Hz, 4H), 7.60(d, J=7.0Hz, 4H), 7. 84(d, J=8.0Hz, 1H), 7.90(d, J=7.0Hz, 1H), 8.03 (d, J=9.0Hz, 1H)

[0420] Also, 1 The H-NMR chart is shown in Figure 65. Note that Figure 65(B) is the same as Figure 65(A). This chart shows an enlarged view of the 7.0 ppm to 8.5 ppm range. From these, It was found that BBAαNB was obtained in this synthesis.

[0421] The obtained 3.9 g solid (BBAαNB) was purified by sublimation using the train sublimation method. The following was performed: Sublimation purification was carried out at a pressure of 3.4 Pa and with argon flowing at a flow rate of 15 mL / min. The process was carried out by heating the solid at 250°C for 16 hours, resulting in 2.4 g of the target solid. The results were obtained with a recovery rate of 62%.

[0422] The HOMO and LUMO levels of BBAαNB were analyzed using cyclic voltammetry (CV). The calculation was based on measurements. The calculation method is shown below.

[0423] The measuring device used is an electrochemical analyzer (manufactured by BAS Corporation, model number: ALS model). A 600A or 600C was used. The solution used in the CV measurement was dehydrated dimethyl as the solvent. Aldrich Formamide (DMF) (manufactured by Aldrich Co., Ltd., 99.8%, catalog number; 227) Using 05-6), the supporting electrolyte is tetra-n-butylammonium perchlorate (nB u4NClO4) (manufactured by Tokyo Chemical Co., Ltd., catalog number: T0836) 100 mmol / Dissolve to a concentration of L, and then dissolve the sample to be measured to a concentration of 2 mmol / L. It was prepared by dissolving it. Furthermore, a platinum electrode (manufactured by BAS Corporation, PT) was used as the working electrode. E Platinum electrode) is used as an auxiliary electrode, and platinum electrode (manufactured by B.A.S. Co., Ltd., for VC-3 P A counter electrode (5 cm) is used, and Ag / Ag is used as the reference electrode. + Electrode (B.A.E.) A RE7 non-aqueous solvent reference electrode manufactured by S Corporation was used. The measurements were taken at room temperature (20°C). The measurements were performed at 25°C. The scan speed during CV measurement was standardized to 0.1V / sec. The oxidation potential Ea [V] and reduction potential Ec [V] were measured relative to the irradiated electrode. Ea is the oxidation- The intermediate potential of the reduction wave was used, and Ec was set as the intermediate potential of the reduction-oxidation wave. Here, the values ​​used in this embodiment The potential energy of the reference electrode relative to the vacuum level is -4.94 [eV]. Since it is known that the HOMO level [eV] = -4.94 - Ea, the LUMO level [eV The HOMO level and LUMO level can be determined from the equation ] = -4.94 - Ec. This can be done. Furthermore, the CV measurement is repeated 100 times, and the acidity measured in the 100th cycle is... The electrical stability of the compound was investigated by comparing the oxidation-reduction wave with the oxidation-reduction wave from the first cycle. .

[0424] As a result, the HOMO level was found to be -5.4 in the measurement of the oxidation potential Ea[V] of BBAαNB. It was found to be 9 eV. On the other hand, the LUMO level was found to be -2.24 eV. Furthermore, in repeated measurements of oxidation-reduction waves, the waveforms at the 1st cycle and 100th cycle are compared. When compared, the peak intensity was 93% in Ea measurements and 92% in Ec measurements. Since it was maintained, BBAαNB has very good resistance to oxidation and reduction. This was confirmed.

[0425] Furthermore, differential scanning calorimetry (DSC measurement) of BBAαNB was performed using PerkinElmer's Py Measurements were taken using ris1DSC. Differential scanning calorimetry was performed at a heating rate of 40°C / min. After raising the temperature from -10°C to 270°C, it is held at that temperature for 1 minute, and then cooled at a rate of 40°C / m The cooling operation to -10°C was performed twice consecutively using DS, and the measurement result from the second measurement was adopted. C measurement revealed that the glass transition temperature of BBAαNB is 84°C.

[0426] (Reference example 4) In this reference example, the 4-"4-(2-naphthyl)phenyl"-4',4 used in the light-emitting element 11 This document explains the synthesis method of "-diphenyltriphenylamine (abbreviation: BBAβNBi)". The structure of BBAβNBi is shown below.

[0427] [ka]

[0428] In a 200 mL three-necked flask, add 4.8 g (10 mmol) of 4-bromo-4',4''- Diphenyltriphenylamine and 2.5 g (10 mmol) of 4-(2-naphthyl) Phenylboronic acid and 0.31 g (0.50 mmol) tris(2-methylphenyl) phosphate Sphin, 40 mL of toluene, 10 mL of ethanol, and 10 mL of potassium carbonate. Add the aqueous solution (2.0 mol / L), stir the flask under reduced pressure, and remove the residue from this mixture. After degassing, the system was subjected to a nitrogen stream, and the mixture was heated to 60°C. After heating, 0 Add 0.11g (0.5 mmol) of palladium(II) acetate, and heat this mixture at 80°C for 1 The mixture was stirred for 0.5 hours. After stirring, it was allowed to cool to room temperature, and the precipitated solid was collected by suction filtration. The sample was washed with toluene, ethanol, and water. The resulting solid was then washed with chloroform. When recovered by suction filtration, 2.9 g of the target substance, a brown solid, was obtained with a yield of 49%. The reaction scheme for this synthesis reaction is shown below.

[0429] [ka]

[0430] The pale yellow solid obtained 1 1H NMR was measured. The data is shown below. 1 1H NMR (Dichloromethane -d2, 500MHz, 500MHz): δ=7.22- 7.25(m, 6H), 7.31(t, J=7.3Hz, 2H), 7.42(t, J=7 .8Hz,4H), 7.46-7.52(m, 2H), 7.55(d, J=7.5Hz, 4H), 7.59-7.63(m, 6H), 7.74(d, J=8.0Hz, 2H), 7 .18-7.83(m, 3H), 7.87(d, J=7.5Hz, 1H), 7.93(t , J=8.7, 2H), 8.11(s, 1H)

[0431] Also, 1 The H-NMR chart is shown in Figure 66. Note that Figure 66(B) is the same as Figure 66(A). This chart shows an enlarged view of the 7.0 ppm to 8.3 ppm range. It was found that BBAβNBi was obtained through this synthesis reaction.

[0432] The obtained 2.9 g solid (BBAβNBi) was sublimated by the train sublimation method. The process was carried out. Sublimation purification was performed under a pressure of 4.0 Pa, with argon flowing at a rate of 15 mL / min. Furthermore, when the solid was heated at 300°C for 16 hours, the target substance was converted to a white solid. 0.9g, obtained with a recovery rate of 65%

[0433] The HOMO and LUMO levels of BBAβNBi are analyzed by cyclic voltammetry (CV). The calculation was based on the measurements. The calculation method is the same as in Reference Example 3.

[0434] As a result, the HOMO level was -5 in the measurement of the oxidation potential Ea[V] of BBAβNBi. It was found to be 47 eV. On the other hand, the LUMO level was found to be -2.38 eV. Furthermore, in repeated measurements of the oxidation-reduction wave, the waveforms from the first cycle and after 100 cycles were observed. When compared, the peak intensity was 82% in Ea measurements and 67% in Ec measurements. Because it maintained this property, BBAβNBi has very good resistance to oxidation and reduction. This was confirmed.

[0435] Furthermore, differential scanning calorimetry (DSC measurement) of BBAβNBi was performed using PerkinElmer equipment. Measurements were taken using a YRIS1DSC. Differential scanning calorimetry was performed at a heating rate of 40°C / min. After raising the temperature from -10°C to 270°C, it is held at the same temperature for 1 minute, and then cooled down at a rate of 40°C / m². The cooling operation to -10°C was performed twice consecutively using DS, and the measurement result from the second measurement was adopted. From the 1C measurement, it was found that the glass transition temperature of BBAβNBi is 97°C, indicating good heat resistance. It was revealed that the compound possesses [a certain characteristic].

[0436] (Reference example 5) In this reference example, the 3-[4-(2-naphthyl)phenyl]-9-(2 The synthesis method for -naphthyl)-9H-carbazole (abbreviation: βNPβNC) is described. The structural formula of NPβNC is shown below.

[0437] [ka]

[0438] In a 200 mL three-necked flask, add 2.3 g (8.1 mmol) of 2-(4-bromophenyl) Naphthalene and 3.4 g (8.1 mol) of 4,4,5,5-tetramethyl-2-[9- (2-naphthyl)-9H-carbazole-3-yl]-1,3,2-dioxaborolane 50 mg (0.16 mmol) of tri(o-tolyl)phosphine and 2.2 g (16 mg) A mole of potassium carbonate was added. After purging the flask with nitrogen, 30 ml of this mixture was added. L of toluene, 10 mL of ethanol, and 8.0 mL of water were added to this mixture under reduced pressure. Degassing was performed by stirring while the mixture was being stirred. After degassing, 18 mg (0.081 mmol) was added to the mixture. l) Palladium(II) acetate was added. This mixture was stirred under a nitrogen stream at 80°C for 4 hours. As a result, a solid precipitated. The precipitated solid was recovered by suction filtration. The aqueous layer of the filtrate was then... Extraction was performed with Luen, and the extract solution and organic layer were washed together with saturated saline solution. The organic layer was then treated with sulfuric acid. The mixture was dried with magnesium and then naturally filtered. The resulting filtrate was concentrated to obtain a solid. Then, the recovered solid is dissolved in approximately 200 mL of heated toluene, and this solution is converted into Celite (Wako). Junyaku Kogyo Co., Ltd., Catalog Number: 537-02305), Alumina, Florizil (Japanese) The sample was filtered by suction through a filter (Kojun Pharmaceutical Co., Ltd., catalog number: 066-05265). When the solid obtained by concentrating the filtrate was recrystallized with toluene, the target substance was obtained as a white powder with a concentration of 2.9 g was obtained in a yield of 72%. The reaction scheme for this synthesis is shown below.

[0439] [ka]

[0440] The obtained white powder (2.9 g) was purified by sublimation using the train sublimation method. The conditions were: pressure 3.9 Pa, argon gas flow rate 5.0 mL / min, 280 The white powder was heated at °C. After sublimation purification, 2.1 g of the white solid βNPβNC was obtained, with a recovery rate of 72%. It was obtained as a percentage.

[0441] The obtained substance 1 1H NMR was measured. The measurement data is shown below. 1 H NMR(CDCl3,300MHz):δ=7.35(ddd,J1=6.6Hz ,J2=1.2Hz,1H),7.42-7.63(m,5H),7.60(dd,J1 =9.6Hz,J2=6.3Hz,2H),7.69-7.76(m,2H),7.82 -8.01(m,10H),8.08-8.13(m,3H),8.25(d,J=7. 8Hz, 1H), 8.46(d,J=1.5Hz, 1H)

[0442] Also, 1 The H-NMR chart is shown in Figure 67. Note that Figure 67(B) is the same as Figure 67(A). This chart shows an enlarged view of the 7.20 ppm to 8.60 ppm range. It was found that βNPβNC was obtained by this synthesis reaction.

[0443] Furthermore, thermogravimetric analysis (TG-DTA) of βNPβNC is performed. We performed a metry-differential thermal analysis. The measurement was performed using a high-vacuum differential thermal balance (Bruker AXS Corporation, TG-D). A TA2410SA was used. At atmospheric pressure, heating rate 10°C / min, under a nitrogen stream (flow velocity: 20 When measured under conditions of 0 mL / min, the relationship between weight and temperature (thermogravimetric analysis) showed that βNP The temperature at which βNC lost 5% of its weight was 431°C. From this, it can be seen that the heat resistance of βNPβNC is It has been shown to be good. [Explanation of symbols]

[0444] 101 First electrode 102 Second electrode 103 EL layer 111 Hole injection layer 112-1 First hole transport layer 112-2 Second hole transport layer 112-3 Third Hole Transport Layer 113 Emitting layer 114 Electron transport layer 115 Electron injection layer 116 Charge generation layer 117 P type layer 118 Electron relay layer 119 Electron injection buffer layer 400 circuit boards 401 First electrode 403 EL layer 404 Second electrode 405 sealant 406 Sealant 407 Sealing substrate 412 pads 420 IC chips 501 First electrode 502 Second electrode 511 First light-emitting unit 512 Second light-emitting unit 513 Charge generation layer 601 Drive circuit section (source line drive circuit) 602 pixel section 603 Drive circuit section (gate wire drive circuit) 604 Sealing substrate 605 Sealant 607 Space 608 Wiring 609 FPC (Flexible Printed Circuit) 610 element substrate 611 Switching FET 612 Current-Controlled FET 613 First electrode 614 Insulators 616 EL layer 617 Second electrode 618 Light-emitting element 901 cabinet 902 Liquid Crystal Layer 903 Backlight Unit 904 cabinet 905 Driver IC 906 terminal 951 circuit board 952 Electrode 953 Insulating layer 954 Partition layer 955 EL layer 956 Electrode 1001 circuit board 1002 Underlying insulating film 1003 Gate Insulator 10:06 Guard Station 1007 🙏 1008 Gate 1020 First interlayer insulating film 1021 Second interlayer insulating film 1022 electrode 1024W First electrode 1024R First electrode 1024G First electrode 1024B First electrode 1025 Bulkhead 1028 EL layer 1029 Second electrode 1031 Sealing substrate 1032 Sealant 1033 Transparent base material 1034R Red colored layer 1034G Green colored layer 1034B Blue colored layer 1035 Black Matrix 1036 Overcoat layer 1037 Third interlayer insulating film 1040 pixel section 1041 Drive circuit section 1042 Peripheral area 2001 cabinet 2002 light source 3001 Lighting device 5000 display area 5001 Display area 5002 Display area 5003 Display area 5004 Display area 5005 Display area 7101 enclosure 7103 Display section 7105 Stand 7107 Display section 7109 Operation Keys 7110 Remote Control Unit 7201 Main Unit 7202 enclosure 7203 Display section 7204 Keyboard 7205 External connection port 7206 Pointing device 7210 Second display unit 7301 enclosure 7302 enclosure 7303 Connection section 7304 Display section 7305 Display section 7306 Speaker section 7307 Recording media insertion section 7308 LED Lamp 7309 Operation Keys 7310 Connection terminal 7311 Sensor 7401 enclosure 7402 Display section 7403 Operation Buttons 7404 External connection port 7405 Speaker 7406 Microphone 7400 mobile phones 9033 Fastener 9034 Switch 9035 Power switch 9036 Switch 9038 Operation switch 9310 Mobile Information Terminal 9311 Display Panel 9312 Display area 9313 Hinge 9315 enclosure 9630 cabinet 9631 Display section 9631a Display section 9631b Display section 9632a Touch panel area 9632b Touch panel area 9633 Solar Cell 9634 Charge / Discharge Control Circuit 9635 Battery 9636 DC-DC converter 9637 Operation Keys 9638 converter 9639 button

Claims

[Claim 1] It has a first electrode, a second electrode, and an EL layer. The EL layer is located between the first electrode and the second electrode. The EL layer comprises a hole injection layer, a first layer, a second layer, a third layer, and a fourth layer. The hole injection layer has an organic acceptor, The hole injection layer is located between the first electrode and the first layer. The second layer is located between the first layer and the third layer. The fourth layer is located between the third layer and the second electrode. The first layer has a first hole transport material, The aforementioned second layer has a second hole transport material, The third layer has a third hole transport material, The fourth layer described above comprises a host material and a light-emitting material. The HOMO level of the second hole transport material is deeper than the HOMO level of the first hole transport material. The HOMO level of the host material is deeper than the HOMO level of the second hole transport material. The HOMO level of the third hole transport material is the same as or deeper than the HOMO level of the host material. A light-emitting element in which the difference between the HOMO level of the second hole transport material and the HOMO level of the third hole transport material is 0.3 eV or less.

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