Light-emitting element

Abstract

An object is to provide a novel light-emitting element. Or, an object is to provide a novel light-emitting element having good luminous efficiency. 【Solution】A light-emitting element having a first electrode, a second electrode, and an EL layer disposed between the first electrode and the second electrode, wherein the EL layer has a light-emitting layer, the light-emitting layer has a first substance and a second substance, the first substance is contained more in the light-emitting layer than the second substance, the second substance exhibits light emission, and the value a of the light-emitting element (the direction of the average transition dipole moment of the second substance in the light-emitting layer is divided into three components x, y, z orthogonal to each other, and assuming that the components horizontal to the first electrode or the second electrode are in the x direction and the y direction, and the vertical component is in the z direction) is 0.2 or less. A light-emitting element is provided. The proportion of the component in the z direction when the component in the z direction is assumed to be in the z direction) is 0.2 or less. A light-emitting element is provided. element is provided. element is provided.

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 light-emitting devices, electronic devices, and lighting devices. One aspect of the present invention relates to the above-mentioned technical field. Not limited to. The technical field of one aspect of the invention disclosed herein relates to a product, method, or manufacturing. This relates to a manufacturing method. Alternatively, one aspect of the present invention relates to a process, machine, or manufacturer. This relates to kucha, or composition of matter. More specifically, one aspect of the technical field of the present invention disclosed herein is semiconductor equipment, Display devices, liquid crystal display devices, light-emitting devices, lighting devices, energy storage devices, memory devices, and methods for driving them. Examples include, or, methods for manufacturing them. [Background technology]

[0002] Due to its potential as a thin and lightweight design, fast response to input signals, and low power consumption, lighting Light-emitting elements (organic EL) that use organic compounds or organometallic complexes as light-emitting materials in devices and display devices. Display devices using (elements) are being developed.

[0003] Organic EL elements are created by applying a voltage with a light-emitting layer sandwiched between electrodes, thereby injecting light from the electrodes. The electrons and holes recombine, causing the light-emitting material to enter an excited state, and this excited state then returns to the ground state. It emits light when it returns. The light spectrum emitted by a light-emitting material is unique to that material. By using different types of light-emitting materials, it is possible to obtain light-emitting elements that emit light of various colors. It is possible.

[0004] Displays and lighting devices using light-emitting elements in this manner are suitable for application to various electronic devices. However, there is still room for improvement in its performance. For example, if the current efficiency of the device is high the higher it is, the better, but its internal quantum efficiency is approaching the theoretical limit value both for fluorescence and phosphorescence. Especially for devices that utilize fluorescence emission, by using the triplet excited state, devices that exhibit an internal quantum efficiency of 25% or more, which is the theoretical limit value of the internal quantum efficiency, have also been realized.

[0005] In order to further improve the current efficiency of a light-emitting device with an improved internal quantum efficiency, extraction efficiency improvement becomes essential.

[0006] Patent Document 1 discloses a light-emitting device in which the emission direction is controlled and the extraction efficiency is improved by forming a film with the light-emitting substance oriented.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0009] One aspect of the present invention aims to provide a novel light-emitting element, or to improve the luminous efficiency. The objective is to provide a superior novel light-emitting element.

[0010] Alternatively, another aspect of the present invention relates to a low-power display module, lighting module The purpose is to provide rakes, light-emitting devices, display devices, electronic devices, and lighting devices, respectively. .

[0011] One aspect of the present invention is sufficient to solve any one of the above-mentioned problems. The description of these problems does not preclude the existence of other problems. Furthermore, one aspect of the present invention is: It is not necessarily required to solve all of these issues. Other issues are detailed below. This will become clear from the description in the document, drawings, and claims, etc. It is possible to extract other issues from the descriptions in the sections and other documents. [Means for solving the problem]

[0012] One aspect of the present invention is a first electrode, a second electrode, and the first electrode and the second electrode A light-emitting element having an EL layer located between it, wherein the EL layer has a light-emitting layer, and the light-emitting The layer has a first substance and a second substance, and in the light-emitting layer the first substance is the second substance It is present in greater quantities than the substance, and the second substance exhibits light emission, and the value of a of the light-emitting element (the light emission The emission from the average transition dipole of the second material in the layer is measured in mutually orthogonal x, y, z triangles. The light is divided into the contributions of the luminescence from the transition dipole of the component and horizontally to the first electrode or the second electrode. Assuming the x and y components are in the x and y directions, and the perpendicular component is in the z direction, the component in the z direction is This is a light-emitting element whose ratio is 0.2 or less.

[0013] Another aspect of the present invention is a light emission in the above configuration in which the second substance is a phosphorescent material. It is an element.

[0014] Another configuration of the present invention is a light-emitting element in which the second substance is an iridium complex. He is a child.

[0015] Another configuration of the present invention is the above configuration in which the external quantum efficiency of the light-emitting element is 25% or more. It is an optical element.

[0016] Another configuration of the present invention is the above configuration wherein the light-emitting layer further comprises a third material, This is a light-emitting element in which substance 1 and the aforementioned third substance form an excited complex.

[0017] Another configuration of the present invention is a light-emitting element in which the second material is a fluorescent material. That is the case.

[0018] Another configuration of the present invention is the configuration wherein the second substance comprises a condensed aromatic hydrocarbon skeleton. It is a light-emitting element made of a certain material.

[0019] Another configuration of the present invention is the above configuration in which the external quantum efficiency of the light-emitting element is 7.5% or more. It is a light-emitting element.

[0020] Another configuration of the present invention is that, in the above configuration, the external quantum efficiency of the light-emitting element is 10% or more. It is a light-emitting element.

[0021] Another configuration of the present invention is that, in the above configuration, the light emission of the light-emitting element includes a delayed fluorescence component. It is a light-emitting element.

[0022] Another configuration of the present invention is a light-emitting element in the above configuration in which the value of a is 0 or more and 0.2 or less. That is the case.

[0023] Another configuration of the present invention comprises the light-emitting element described above, a transistor, or a substrate. It is a light-emitting device.

[0024] Other configurations of the present invention include the light-emitting device described above, and a sensor, an operating button, a speaker, or It is an electronic device that has a microphone and [something else].

[0025] Another configuration of the present invention is a lighting device having the light-emitting device described above and a housing.

[0026] 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 may have a light-emitting device. [Effects of the Invention]

[0027] In one aspect of the present invention, a novel light-emitting element can be provided, or a light-emitting element with good luminescence efficiency can be provided. Novel light-emitting elements can be provided.

[0028] Alternatively, another aspect of the present invention relates to a low-power display module, lighting module We can provide lumens, light-emitting devices, display devices, electronic devices, and lighting devices, respectively.

[0029] One aspect of the present invention is sufficient if it achieves any one of the effects described above. The description of these effects does not preclude the existence of other effects. Furthermore, one aspect of the present invention is not necessarily However, it is not necessary to have all of these effects. Other effects are described in the specification. This will become clear from the descriptions in the drawings and claims, and the specification, drawings, and claims will be clear from the description, drawings, and claims. It is possible to extract other effects from any of these descriptions. [Brief explanation of the drawing]

[0030] [Figure 1] A diagram illustrating the calculation flow for the external quantum efficiency of a fluorescent light-emitting element. [Figure 2] A diagram showing the change in emission intensity depending on the orientation of the transition dipole and the observation angle. [Figure 3] Conceptual diagram of a light-emitting element. [Figure 4] A diagram illustrating an example of a method for fabricating a light-emitting element. [Figure 5] A diagram illustrating an example of a device for fabricating light-emitting elements. [Figure 6] Conceptual diagram of an active matrix light-emitting device. [Figure 7] Conceptual diagram of an active matrix light-emitting device. [Figure 8] Conceptual diagram of an active matrix light-emitting device. [Figure 9] Conceptual diagram of a passive matrix type light-emitting device. [Figure 10] A diagram representing a lighting device. [Figure 11] A diagram representing electronic devices. [Figure 12] A diagram representing a light source device. [Figure 13] A diagram representing a lighting device. [Figure 14] A diagram representing a lighting device. [Figure 15] A diagram showing an in-vehicle display device and lighting system. [Figure 16] A diagram representing electronic devices. [Figure 17] A diagram representing electronic devices. [Figure 18] Conceptual diagram of a light-emitting element for measurement. [Figure 19] A diagram showing the external quantum efficiency-luminance characteristics of light-emitting element 1. [Figure 20] A diagram illustrating a method for measuring the angle dependence of emission spectra. [Figure 21] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 1-1. [Figure 22] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 1-1. [Figure 23] 2D contour plot obtained from calculations of light-emitting element 1-1. [Figure 24] A diagram showing the external quantum efficiency-luminance characteristics of light-emitting element 2. [Figure 25] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 2-1. [Figure 26] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 2-1. [Figure 27] 2D contour plot obtained from calculations of light-emitting element 2-1. [Figure 28] A diagram showing the external quantum efficiency-luminance characteristics of the light-emitting element 3. [Figure 29] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 3-1. [Figure 30] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 3-1. [Figure 31] 2D contour plot obtained from calculations of light-emitting element 3-1. [Figure 32] A diagram showing the external quantum efficiency-luminance characteristics of the light-emitting element 4. [Figure 33] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 4-1. [Figure 34] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 4-1. [Figure 35] 2D contour plot obtained from calculations of light-emitting element 4-1. [Figure 36]A diagram showing the external quantum efficiency-luminance characteristics of the light-emitting element 5. [Figure 37] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 5-1. [Figure 38] A diagram showing the external quantum efficiency-luminance characteristics of the light-emitting element 6. [Figure 39] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 6-1. [Figure 40] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 6-1. [Figure 41] 2D contour plot obtained from calculations of light-emitting element 6-1. [Figure 42] A diagram showing the external quantum efficiency-luminance characteristics of the light-emitting element 7. [Figure 43] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 7-1. [Figure 44] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 7-1. [Figure 45] 2D contour plot obtained from calculations of light-emitting element 7-1. [Figure 46] A diagram showing the external quantum efficiency-luminance characteristics of the light-emitting element 8. [Figure 47] This figure shows the EL emission spectral area intensity (measured and calculated) as a function of the detector angle (θ) of the light-emitting element 8-1. [Figure 48] 2D contour plot showing the angular dependence of the EL emission spectrum of light-emitting element 8-1. [Figure 49] 2D contour plot obtained from calculations of light-emitting element 8-1. [Modes for carrying out the invention]

[0031] 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.

[0032] The process from carrier recombination to light emission in an organic EL element that exhibits fluorescence emission is explained using Figure 1. Let me explain. First, when a voltage is applied to an organic EL element, holes are produced from the anode and electrons are produced from the cathode. These are each injected into the EL layer. The injected carriers (holes and electrons) emit within the EL layer. They are transported toward the light layer, and recombination occurs when they come into contact with each other at a certain position. The rate at which this recombination occurs is called the carrier balance (γ). Energy excites organic materials, but the ratio of exciton generation is one singlet exciton to one exciton. This results in a triplet exciton (3). This ratio is called the singlet exciton generation ratio (α). Singlet excitons generated by photomaterials produce fluorescence quantum yields (Φ) of organic compounds. f It emits light according to the following, and Singlet excitons generated by other organic compounds undergo energy transfer to the luminescent material via Φ f It emits light according to the following. The proportion of the light emitted in this way that is observed outside the light-emitting element is the organic This represents the light extraction efficiency (χ) of the EL element, and the external quantum efficiency (μ) of the fluorescent light-emitting element. ext ) is, Carrier balance (γ), singlet exciton generation rate (α), fluorescence quantum yield (Φ) f ), light extraction It is the product of the efficiencies (χ) and is expressed by the following equation (1).

[0033]

number

[0034] Of these, Φ fThis is a value specific to the light-emitting material, and there is a fixed value for each light-emitting material. Also, γ is For EL elements with a multilayer structure, it can be assumed to be approximately 1. Therefore, when using the same material... The terms that can be expected to improve luminescence efficiency through the device structure are light extraction efficiency (χ) and singlet excitation. There are two possible outcomes: the progeny generation rate (α).

[0035] The singlet exciton generation ratio α is the ratio of triplet excitons to singlet excitons. triplet-triplet annihilation (TT) The system can be improved if mechanisms such as A) exist.

[0036] The light extraction efficiency (χ) is related to the structure and lamination of the light-emitting device, but on the glass substrate... In organic EL elements, it is usually said to be 20% to 30%. However, this Since it is assumed that the emission is isotropic, if anisotropy occurs in the emission, this value will change. To transform.

[0037] It has been found that the emission of light from luminescent materials occurs perpendicular to the transition dipole moment of the molecule. Therefore, by controlling the orientation state of the molecules, it is possible to improve the extraction efficiency (χ). ru.

[0038] Spectroscopic ellipsometry is used as a method for evaluating the molecular orientation state in amorphous organic thin films. There is a method that can be used by measuring the refractive index (n) and extinction coefficient (k) of the organic material. Rough values ​​can be analyzed. In fact, among the materials used in light-emitting devices, long linear molecules, It has been reported that in molecules spread in a planar manner, there is a molecular orientation parallel to the thin film surface. (See Non-Patent Document 1).

[0039] However, actual light-emitting devices are constructed by stacking multiple organic thin films, and the light-emitting material is It is dispersed in small amounts within the host material. Therefore, in actual light-emitting devices, the light-emitting material The extinction coefficient (k) could not be determined with high accuracy, and the luminescent material was less than 10 wt% in the luminescent layer. At this concentration, it is difficult to determine the molecular orientation using the method described above.

[0040] Therefore, the inventors adopted a method for estimating molecular orientation from the light emission state of the element. The emission angle dependence of the light emission intensity of an optical element (spatial emission pattern) is determined by the average transition bifurcation of the light-emitting material. This reflects the orientation of the poles. If we can analyze this spatial distribution, we can investigate the orientation state of the light-emitting element. Yes, it is possible. This method allows us to observe and analyze the light emission itself from the light-emitting element, so the light-emitting material is not affected. Even if the concentration is low, if it is emitting light, the orientation of the light-emitting material within the light-emitting layer is important. It becomes possible to check if it is located there.

[0041] In practice, the angle dependence of the measured emission intensity and the orientation of the emission molecules in the device simulator are used. The angle dependence of the luminescence intensity is calculated assuming the parameter a (see equation (2) below). By comparing it with the calculated value, a reasonable numerical value for the molecular orientation parameter a is estimated, and then applied to the light-emitting element. The orientation state of the luminescent material can be investigated (see Non-Patent Document 2). Furthermore, the shape of the emission spectrum obtained from the device simulator is also considered, and the emission spectrum We also compared measured and calculated values ​​regarding the shape and angle of the emission spectrum. Adjustments are being made. In addition, the luminescence intensity in actual measurements and simulations is as follows: Instead of using the emission intensity at a specific wavelength, the area intensity of the emission spectrum is used. Unlike Non-Patent Document 2, these newly applied methods allow for highly accurate parameter analysis. An estimate for item A is now available.

[0042] Next, we will explain the molecular orientation parameter a. Figure 2 shows the measurement of the spatial distribution of emission intensity. This shows the relationship between the observation direction of the measuring instrument and the components of each mutually orthogonal transition dipole on the substrate. As shown in the figure, the light emission from the average transition dipole in the light-emitting material within the light-emitting layer (that is, The light emitted from the light-emitting element (the actual light emission observed from the light-emitting element) is divided into components in the x-axis direction that are orthogonal to each other (TEh component). From each transition dipole of the y-axis component (TMh component) and z-axis component (TMv component) It is decomposed into the contribution of light emission. In other words, there are three types of transitions in the x, y, and z axis directions. It is assumed that dipole orientations exist in a certain ratio, and in this case, from each transition dipole The light emission pattern of a light-emitting element is determined by the summation of the light emitted. As described below. The parameter related to that ratio is 'a'.

[0043] Here, as mentioned above, the emission from the molecule is in a direction perpendicular to the transition dipole moment ( It is known that it is emitted in any direction within the vertical plane. Divided into the three directions mentioned above. Of the components, the TEh component and the TMh component (in the x-axis and y-axis directions) are horizontally transferred within the substrate plane. Because it is a shifting dipole, its light emission direction is perpendicular to the substrate, resulting in easily extractable light. It can be said that this is the component. On the other hand, the TMv component (z-axis direction) is a transition dipole perpendicular to the substrate plane. Therefore, the direction of light emission is horizontal to the substrate, resulting in light emission that is difficult to extract. It is an ingredient.

[0044] In Figure 2, the shape emanating from the center of the arrows representing the orientation of the transition dipoles of each component indicates the direction of the detector. is a schematic diagram showing the emission intensity entering the detector in that direction when the angle is changed from the front of the substrate (θ = 0 degrees) to almost horizontal with respect to the substrate (θ = 90 degrees), and the linear distance from the center is proportional to the intensity.

[0045] Since the detector exists in the direction in which light is emitted, for the TEh component, the intensity of the detected light (i.e., the linear distance from the center of the arrow of the figure emerging from the center of the arrow in the figure) is constant, and the figure emerging from the center of the arrow in the figure shows a regular sector. On the other hand, the figures emerging from the center of the arrow in the TMh component and the TMv component are distorted, indicating that the intensity of the detected light changes significantly depending on the angle θ of the detector with respect to the substrate. As shown in the figure, the TMh component has a strong intensity in the region where θ is small (close to the front with respect to the substrate), and the TMv component has a strong intensity in the region where θ is large (the direction with an angle with respect to the substrate). At this time, the emission intensity measured by the measuring instrument (the emission intensity regarding the wavelength λ at a certain angle θ: I (θ,λ)) can be expressed as Equation (2). λ

[0046]

Equation

[0047] In the equation, I TMv , I TMh , I TEh represent the spatial intensity distribution of the light emitted from the transition dipole in the arrangement shown in Figure 2. In the equation, a represents the ratio of the transition dipole (TMv component) arranged perpendicular to the film surface, and 1 - a represents the ratio of the transition dipole arranged horizontally (TMh component, TEh component). That is, a represents the parameter representing the orientation of the transition dipole of the emitting molecule. ​​​​​​​​​​​It can also be seen as a meter.

[0048] Note that in the formula, a is T if the transition dipole is positioned only in a completely horizontal direction with respect to the substrate. The Mv component disappears, so a=0. On the other hand, the transition dipole is only perpendicular to the substrate. If they are arranged, a=1. Also, if the orientation of the transition dipole is random, the transition The ratio of each component of the dipole is considered to be isotropic, 1:1:1 with respect to the x, y, and z axes. Therefore, the component perpendicular to the substrate (TMv component) and the component horizontal to the substrate (TMh component and Since the TEh component is in a 1:2 ratio, a = 1 / 3 (approximately 0.33).

[0049] Here, as mentioned above, TEh Its strength is constant regardless of the angle, TMv , I TMh As mentioned above, its size changes depending on the angle (θ) of the substrate relative to the measuring instrument, so θ is By varying the luminescence intensity and measuring it, the value of 'a' can be determined from the change in that intensity with respect to θ. It is possible.

[0050] Furthermore, in that case, the strength does not change depending on the angle. TEh This interferes with the measurement. However, Therefore, the amplitude direction of the electric field of the emitted light is the same as the direction of the transition dipole moment, TEh These are S waves and I waves. TMv , I TMh Since it is a P-wave, it is linearly polarized in the direction perpendicular to the substrate surface. By inserting photons, it is possible to measure while excluding the TEh component.

[0051] Furthermore, when comparing the TMv and TMh components, the emission direction of the TMh component is primarily on the substrate. The direction of emission of the TMv component is mainly horizontal to the substrate, but the emission from the solid In the resulting light-emitting element, much of the TMv component is totally reflected, making it difficult to extract externally. This is not possible. On the other hand, the luminescence of the TMh component is more easily extracted externally compared to the TMv component. Furthermore, in a light-emitting element with an optically optimized film thickness, the light emission direction is primarily the substrate Because the emission of the TMh component, which is perpendicular to the direction, is amplified by interference, the emission of the TMh component is amplified. The degree increases (and therefore the luminescence efficiency is maximized). In other words, the orientation parameter a becomes extremely Unless the value is close to 1, in optically optimized devices, the TMv component and TM A very large difference occurs in the emission intensity of the h component. In other words, the luminescence efficiency is maximized. In light-emitting devices, most of the observed luminescence is the TMh component. If the difference in emission intensity between the v component and the TMh component is large, the one with the smaller intensity (in this case) It is difficult to experimentally extract the contribution of the TMv component from the angular distribution of emission intensity.

[0052] Therefore, in this embodiment, interference effect is used to minimize the light emission intensity in the direction of the front of the substrate. In other words, by minimizing the emission of the TMh component using optical interference, the TMh component The element was modified to make it easier to determine the ratio of the TMv component, i.e., the value of parameter a. Prepare and perform the measurement. Specifically, the distance between the light-emitting region and the cathode is nλ / 2 (nλ / 2) By doing so, an element with reduced brightness in the direction of the substrate's front is fabricated, and measurements are performed using this element. The adjustment is usually performed by thickening the electron transport layer to which alkali metals are added, but the film Due to the limitations of its conductivity, this can lead to an increase in the drive voltage and an imbalance in the carrier balance. It is inexpensive. Therefore, this film thickness adjustment requires a hole transport material and an accessory for the said hole transport material. It is preferable to use a composite material containing a material that exhibits ptogenic properties. The composite material is used in the EL layer. It is preferable to use it in the hole injection layer. Alternatively, it may be used between the electron injection layer and the cathode. .

[0053] Examples of hole-transporting materials used in composite materials include aromatic amine compounds and carbazole derivatives. various types of compounds, including aromatic hydrocarbons and polymer compounds (oligomers, dendrimers, polymers, etc.) Organic compounds can be used. Furthermore, as hole-transporting substances used in composite materials... , 10 -6 cm 2 It is preferable that the material has a hole mobility of / Vs or higher. , specifically, examples of organic compounds that can be used as hole transporting materials in composite materials. List them.

[0054] As for hole-transporting materials that can be used in composite materials, N,N'-di(p-tril) -N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4'- Bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation) :DPAB), N,N'-bis{4-[bis(3-methylphenyl)amino]phenyl} -N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (abbreviation: DN) TPD), 1,3,5-Tris[N-(4-diphenylaminophenyl)-N-phenyl Aromatic amine compounds such as aminobenzene (abbreviation: DPA3B), 3-[N-(9-phenylene) Nilcarbazole-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviated) Name: PCzPCA1), 3,6-bis[N-(9-phenylcarbazole-3-yl)- N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N -(1-naphthyl)-N-(9-phenylcarbazole-3-yl)amino]-9-phenylcarbazole Nilcarbazole (abbreviation: PCzPCN1), 4,4'-di(N-carbazolyl)bife Nyl (abbreviated as CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]bene Zen (abbreviation: TCPB), 9-[4-(10-phenyl-9-antryl)phenyl]- 9H-carbazole (abbreviation: CzPA), 1,4-bis[4-(N-carbazolyl)phen Carbazole derivatives such as [nyl]-2,3,5,6-tetraphenylbenzene, 2-ter t-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 2 -tert-butyl-9,10-di(1-naphthyl)anthracene, 9,10-bis(3 ,5-diphenylphenyl)anthracene (abbreviation: DPPA), 2-tert-butyl- 9,10-Bis(4-phenylphenyl)anthracene (abbreviation: t-BuDBA), 9, 10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylant Helical (abbreviation: DPA Anth), 2-tert-butylanthracene (abbreviation: t-BuA nth), 9,10-bis(4-methyl-1-naphthyl)anthracene (abbreviation: DMNA) ), 2-tert-butyl-9,10-bis[2-(1-naphthyl)phenyl]anthra Sen, 9,10-bis[2-(1-naphthyl)phenyl]anthracene, 2,3,6,7 -Tetramethyl-9,10-di(1-naphthyl)anthracene, 2,3,6,7-tetra Methyl-9,10-di(2-naphthyl)anthracene, 9,9'-bianthryl, 10, 10'-Diphenyl-9,9'-biantryl, 10,10'-bis(2-phenylphenyl Nil)-9,9'-biantril, 10,10'-bis[(2,3,4,5,6-penta Phenyl)phenyl]-9,9'-bianthryl, anthracene, tetracene, rubrene Aromatic carbonized water such as perylene and 2,5,8,11-tetra(tert-butyl)perylene The element is mentioned. In addition, pentacene, coronene, etc. can also be used. Vinyl It may be an aromatic hydrocarbon having a skeleton, and an aromatic hydrocarbon having a vinyl skeleton. For example, 4,4'-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DP) VBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl]anthracene Examples include (abbreviated as DPVPA).

[0055] In particular, as a hole transport material, 4-[4-(9-phenyl-9H-fluorene-9 -yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 1,3,5-tri(dibenzothiophen-4-yl)-benzene (abbreviation: DBT3P-I) I) 4,4'-(biphenyl-2,2'-diyl)-bis-dibenzothiophene (abbreviation) :oDBTBP-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-full Oren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4 -[3-(triphenylene-2-yl)phenyl]dibenzothiophene (abbreviation: mDBT) PTp-II), 3,6-di-(dibenzothiophen-4-yl)-9-phenyl-9H -Carbazole (abbreviation: DBT2PC-II), 4-[3-(9,10-diphenyl-2 -Anthryl)phenyl]dibenzothiophene (abbreviation: 2mDBTPPA-II), 4- [3-(9,10-diphenyl-2-anthryl)phenyl]dibenzofuran (abbreviation: 2) mDBFPPA-II) and 4-[4-(9-phenylanthracene-10-yl)phenyl Dibenzothiophene derivatives such as [nyl]dibenzothiophene (abbreviation: mDBTPA-II) or dibenzofuran derivatives and 1-[3,5-di(naphthalene-1-yl)phenyl ]Naphthalene (abbreviation: N3P), 9-[3,5-di(phenanthrene-9-yl)phen Phenanthrene (abbreviation: Pn3P), 1,2,3,4-tetraphenylnaphthalene ( Abbreviation: P4N), 2-[3,5-di-(naphthalene-2-yl)-phenyl]-naphthalene βN3P (abbreviation: βN3P) and 9,9'-(biphenyl-3,3'-diyl)-diphenane Naphthalene skeletons such as mPnBP, phenanthrene skeletons, or tripheni A hydrocarbon compound having a molecular weight of 350 to 2000, in which substituents are attached to a len skeleton. The composite material used does not absorb light from the visible light region to the near-infrared region, therefore, this composite material was used. The results of measuring the light-emitting element fabricated using this method showed good agreement with the calculated results, and the value of a was determined with good accuracy. It can be sought.

[0056] Also, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphen Nylamine (abbreviation: PVTPA), poly[N-(4-{N'-[4-(4-diphenyl [amino)phenyl]phenyl-N'-phenylamino}phenyl)methacrylamide]( Abbreviation: PTPDMA), poly[N,N'-bis(4-butylphenyl)-N,N'-bis High molecular weight compounds such as (phenyl)benzidine (abbreviated as Poly-TPD) can also be used. can.

[0057] As an acceptor substance, 7,7,8,8-tetracyano-2,3,5,6-tetraph Examples include ruoloquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. Furthermore, transition metal oxides can be cited. Also, in groups 4 through 8 of the periodic table... We can list the oxides of the metals to which they belong. Specifically, vanadium oxide, niobium oxide, Tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, ray oxide Tium is preferred because of its high electron-accepting ability. In particular, molybdenum oxide is stable even in the atmosphere. Therefore, it is preferable because it has low hygroscopicity and is easy to handle.

[0058] Because this composite material has high conductivity, even when the film is made thick, the driving voltage does not tend to increase, and the carrier It also has the advantage of maintaining balance.

[0059] In addition, although a light-emitting element with a special structure is used for the measurement, the structure of the light-emitting layer The structure is formed in the same way as a normal light-emitting element, and the orientation evaluation results are similar to those of a light-emitting layer. This can also be applied to the orientation state of light-emitting elements.

[0060] This type of light-emitting element is actually made to emit electroluminescent light, and a linear polarizer is inserted perpendicularly into the substrate to produce light. The angle dependence of the intensity is measured. The emission intensity can also be expressed as the intensity at a certain wavelength. In one embodiment of the present invention, expressing the emission spectral intensity as an integrated value provides a more accurate verification. This is preferable as it allows for such actions.

[0061] These experimental values ​​are obtained using an organic device simulator (semiconducting emission simulator). ve thin film optics simulator:setfos;Cyber By comparing with the calculation results by Net System Co., Ltd., the a in the light-emitting element is The value can be determined. In this calculation, the spectral shape and layered structure of the luminescent material are used. By entering the film thickness, refractive index, extinction coefficient, and the position and width of the light-emitting region, any of the entered values ​​can be used. At a given value of 'a', the emission intensity (spectrum) can be calculated for a given angle θ.

[0062] Note that the position of the light-emitting region cannot be measured, so it will be done based on assumptions. The light-emitting region is specified by the key of the light-emitting layer. Based on empirical observations of carrier transportability, etc., it can be assumed that fixing it in one place in the film thickness direction is the most re-attachable Light emission positions that are thought to have a high probability of success (for example, if the electron transport properties of the light emission layer are higher than the hole transport properties) First, fix the area near the interface between the hole transport layer and the light-emitting layer, and then exponentially calculate the recombination probability from that position. If we perform calculations assuming that there is an expansion of the emission region that reduces the spectral distribution, we can obtain a spectrum close to that of actual measurements. Good calculation results for the shape can be obtained.

[0063] The present inventors have found that in a light-emitting element, the value of a calculated by the above method is preferably 0.2 or less. By setting the value to between 0 and 0.2, it is possible to obtain a light-emitting element with very good luminescence efficiency. They discovered that...

[0064] Here, we consider the light extraction efficiency in each orientation state. The transition dipole moment is randomly distributed. Compared to when it is oriented (a=1 / 3≈0.33), when it is perfectly oriented horizontally to the substrate (a= When 0), the transition dipoles of one-third of the molecules that were perpendicular to the substrate during random orientation are It becomes horizontal. Therefore, the proportion of transition dipoles horizontal to the substrate surface is 1.5 compared to random orientation. It doubles.

[0065] As mentioned earlier, the light emission observed in an optimized light-emitting element is almost entirely These luminescent components originate from molecules that are horizontally oriented, while those from vertically oriented molecules... The luminescence emitted (i.e., the TMv component) is relatively weak enough to be negligible. Therefore, in the case of random orientation, the emission from one-third of the molecules is not effectively extracted. This can be considered. On the other hand, when a is 0, a transition bipolar horizontal to the substrate is formed as described above. Since the proportion of offspring is 1.5 times that of random orientation, the portion that contributes to the observed luminescence The proportion of offspring also increases by approximately 1.5 times, and the efficiency of light extraction also increases by approximately 1.5 times.

[0066] Thus, in one embodiment of the present invention, the light-emitting element is such that the value of a is 0.2 or less, Compared to the case of a solid orientation, more light can be extracted externally, resulting in external quantum It is possible to provide a light-emitting element with good efficiency. Note that when the value of a is 0.2, horizontal The proportion of transition dipoles in orientation is 1.2 times that of random orientation, resulting in 1.2 times the extraction efficiency. do.

[0067] Furthermore, since the electrodes of the light-emitting element are positioned horizontally on the substrate, the transition dipole horizontal to the substrate emits light. It can be said that the element is horizontal to either the first or second electrode.

[0068] Up to this point, the explanation has been given using a fluorescent light-emitting device, where the light-emitting material is a fluorescent substance, as an example. However, it can also be applied when the light-emitting material is a phosphorescent substance. By using a phosphorescent material as the light-emitting material, a light-emitting element exhibiting very good luminescence efficiency can be obtained. This is possible. Furthermore, the phosphorescent material is preferably an iridium complex. By having a light-emitting layer with a value of 0.2 or less, the phosphorescent light-emitting element This makes it easier to provide light-emitting elements that exhibit good efficiency, such as an external quantum efficiency of 25% or more. Furthermore, if the phosphorescence quantum yield of the luminescent material is very high (for example, 0.84 or higher, preferably 0. If the value is 9 or higher, it exhibits an external quantum efficiency of 30% or more, exceeding the theoretical limit. It is also possible to provide light-emitting elements that exhibit very good efficiency. Furthermore, with phosphorescent light-emitting elements... The light-emitting layer contains a host material, a light-emitting material, and a third substance, and the host material and the third substance A configuration that forms an excited complex improves the efficiency of energy transfer and reduces the driving voltage, among other benefits. This configuration is preferable because it has a positive effect.

[0069] If the light-emitting material is a fluorescent light-emitting material, the light-emitting material contains a condensed aromatic hydrocarbon skeleton. It is preferable that it be a substance for molecular orientation. The emission layer has a value of a of 0.2 or less. Because it is an optical element, the extraction efficiency is 1.2 times higher, therefore in fluorescent light-emitting devices If the fluorescence quantum yield of the light-emitting material is very high (for example, 0.84 or higher, preferably 0.9 or higher), If so, a good external quantum efficiency of 7.5% or higher, exceeding the theoretical limit. It is also possible to provide light-emitting elements that exhibit high efficiency. Furthermore, it is possible to simultaneously incorporate mechanisms such as TTA. This also provides a light-emitting element that exhibits very good efficiency, with an external quantum efficiency of 10% or more. This becomes possible. In light-emitting devices that simultaneously possess TTA, a delayed fluorescence component is observed.

[0070] <<Light-emitting element>> Next, an example of a light-emitting element, which is one aspect of the present invention, will be described in detail below using Figure 3(A). explain.

[0071] The light-emitting element in this embodiment consists of a first electrode 101 and a second electrode 102. A pair of electrodes, and an EL layer 103 provided between the first electrode 101 and the second electrode 102. It is composed of the following. The first electrode 101 functions as the anode, and the second electrode 102 is The following will explain how it functions as a cathode.

[0072] For the first electrode 101 to function as an anode, it must have a large work function (specifically 4 Formed using metals, alloys, conductive compounds, and mixtures thereof (0.0 eV or higher). This is preferable. Specifically, for example, indium oxide-tin oxide (ITO:Indiu (m Tin Oxide), silicon or silicon oxide containing indium oxide Indium oxide containing tin, indium oxide-zinc oxide, tungsten oxide, and zinc oxide Examples include um (IWZO). These conductive metal oxide films are usually sputtered. The film is deposited by a specific method, but it can also be fabricated using methods such as the sol-gel method. Examples of fabrication methods. Indium oxide-zinc oxide is an oxidation product of 1 to 20 wt% of indium oxide. One method involves forming the material using a sputtering technique with a target containing zinc. Indium oxide (IWZO) containing tungsten oxide and zinc oxide is an indium oxide. Contains 0.5 to 5 wt% tungsten oxide and 0.1 to 1 wt% zinc oxide relative to um. It can also be formed by sputtering using a target. In addition, gold (A u), platinum (Pt), nickel (Ni), tungsten (W), chromium (Cr), molybdenum Density (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), and Examples include nitrides of metallic materials (e.g., titanium nitride). Graphene can also be used. Yes, it is possible. Furthermore, the composite material described later is used in the layer that contacts the first electrode 101 in the EL layer 103. By using this method, it becomes possible to select electrode materials regardless of the work function.

[0073] The EL layer 103 has a laminated structure and includes at least an emissive layer. Other layers include These include hole injection layers, hole transport layers, electron transport layers, electron injection layers, carrier block layers, and intermediate layers. The light-emitting element can be constructed by combining them as appropriate. In this embodiment, EL Layer 103 consists of a hole injection layer 111, a hole transport layer 112, and a light-emitting layer 11 on top of the first electrode 101. 3. A configuration having a stacked structure in the order of electron transport layer 114 and electron injection layer 115 will be described. Examples of materials that make up each layer are shown below.

[0074] The hole injection layer 111 is a layer containing a material with high hole injection potential. This includes molybdenum oxide and vanadium. Uses materials such as zinc oxide, ruthenium oxide, tungsten oxide, and manganese oxide. This can be done. In addition, phthalocyanine (abbreviation: H2Pc) and copper phthalocyanine (abbreviation: Cu Phthalocyanine compounds such as PC, 4,4'-bis[N-(4-diphenylaminophosphate) [phenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N'-bis{4- [bis(3-methylphenyl)amino]phenyl]-N,N'-diphenyl-(1,1' Aromatic amine compounds such as -biphenyl)-4,4'-diamine (abbreviation: DNTPD), or i is poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonic acid) (abbreviation) Polymers such as :PEDOT / PSS, 7,7,8,8-tetracyano-2,3,5,6 - Holes can also be formed by tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, etc. An injection layer 111 can be formed.

[0075] Furthermore, the hole injection layer 111 is a composite material containing a hole transporting substance and an acceptor substance. Composite materials can be used. Composite materials can be used when adjusting the film thickness of light-emitting elements. Since it is the same composite material that was described as suitable, a repeated explanation will be omitted. By using a composite material as a hole injection layer, the material of the first electrode can be selected regardless of the work function. You will be able to choose.

[0076] By forming the hole injection layer 111, the hole injection performance is improved, and the driving voltage is reduced. This makes it possible to obtain a light-emitting element.

[0077] The hole transport layer 112 is a layer containing a hole-transporting substance. The hole-transporting substance is: For example, 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviated) Name: NPB) or N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1, 1'-Biphenyl]-4,4'-diamine (abbreviation: TPD), 4,4',4''-Tris (N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4',4 Tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (Abbreviation: MTDATA), 4,4'-bis[N-(spiro-9,9'-bifluorene-2) -yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4'- (9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), etc. Aromatic amine compounds and the like can be used. The substances described herein have high hole transport properties. , mainly 10 -6 cm 2It is a material having a hole mobility of / Vs or greater. Also, the above-mentioned composite material The organic compounds listed as hole-transporting substances in the material can also be used in the hole transport layer 112. Yes, it is possible. Furthermore, the layer containing the hole-transporting substance is not limited to a single layer, but can also consist of the aforementioned substances. It may also consist of two or more layers stacked on top of each other.

[0078] Even if the light-emitting layer 113 is a layer that exhibits fluorescence emission, it may be a layer that exhibits phosphorescence emission or a thermally activated layer. Any layer exhibiting extended fluorescence (TADF) is acceptable. Furthermore, even a single layer is acceptable. It may consist of multiple layers containing different light-emitting materials. In this case, a layer containing phosphorescent material and a layer containing fluorescent material are stacked. This is also good. In this case, it is preferable to use the excitation complex described later in the layer containing the phosphorescent material. It seems so.

[0079] Examples of fluorescent materials that can be used include the following: The following fluorescent luminescent substances can also be used. N,N'-diphenyl-N,N'-bis[4-( 9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviated) Name: 1,6FLPAPrn), N,N'-bis(3-methylphenyl)-N,N'-bis [3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-dia Min (abbreviation: 1,6mMemFLPAPrn), N,N'-diphenyl-N,N'-bis [3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-dia Min (abbreviation: 1,6mFLPAPrn), N,N'-bis(2,6-dimethylphenyl) -N,N'-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyre N-1,6-diamine (abbreviation: 1,6oDMemFLPAPrn), N,N'-bis[4 -(dibenzofuran-4-yl)phenyl]-N,N'-diphenylpyrene-1,6- Diamine (abbreviation: 1,6FrBAPrn-II), N,N'-bis[3-(dibenzofura N-4-yl)phenyl]-N,N'-diphenylpyrene-1,6-diamine (abbreviation: 1,6mFrBAPrn-II), N,N'-(pyrene-1,6-diyl)bis[(N- Phenylbenzo[b]naphtho[1,2-d]furan)-8-amine (abbreviation: 1,6Bn fAPrn-02), N,N'-(pyrene-1,6-diyl)bis[(6,N-dipheny Rubenzo[b]naphtho[1,2-d]furan)-8-amine (abbreviation: 1,6BnfAP) rn-03), 9,10-bis[N-phenyl-N-(9-phenylcarbazole-3- Examples include ylaminoanthracene (abbreviated as PCA2A) and coumarin 545T. 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 has excellent reliability and is easy to orient molecules.

[0080] Examples of materials that can be used as phosphorescent materials in the light-emitting layer 113 include, for example, Examples include the following: Tris{2-[4-(2-adamantyl)-3-methyl -4H-1,2,4-triazole-5-yl-κN]phenyl-κC}iridium(I II) (abbreviation: [Ir(Mptz-Adm2)3]), Tris{2-[4-(4-cyano -2,6-diisobutylphenyl)-5-(2-methylphenyl)-4H-1,2,4- Triazole-3-yl-κN 2]phenyl-κC}iridium(III) (abbreviation: Ir (mpptz-diBuCNp)3), Tris{2-[4-(4-cyano-2,6-dimethyl Tylphenyl)-5-(2-methylphenyl)-4H-1,2,4-triazole-3- Il-κN 2 ]phenyl-κC}iridium(III) (abbreviation: Ir(mpptz-dm CNp)3), Tris{2-[1-(4-cyano-2,6-diisobutylphenyl)-1 H-imidazole-2-yl-κN 3 ]phenyl-κC}iridium(III) (abbreviation: Azoles like Ir(pim-diBuCNp)3 (especially triazoles and imidazoles) Organometallic iridium complexes having a (L) skeleton, and (acetylacetonato)bis(6-ter t-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBu ppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl) -4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2( (acac)), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl )-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm) 2(acac)]), (acetylacetonato)bis(4,6-diphenylpyrimidinato) Iridium(III) (abbreviation: [Ir(dppm)2(acac)]), (acetylacetate) Tonato)bis(4,5,6-triphenylpyrimidinato)iridium(III) (abbreviation: [Ir(tppm)2(acac)]), bis{2-[6-(3,5-dimethylphenyl )-4-pyrimidinyl-κN3]-4,6-dimethylphenyl-κC}(2,6-dimethylphenyl Ru-3,5-heptandionato-κ 2O,O') Iridium(III) (Abbreviation: [Ir( dmdppm)2(dibm)], bis{2-[6-(3,5-dimethylphenyl)-4 -pyrimidinyl-κN3]-4,6-dimethylphenyl-κC}(2,2',6,6'- Tetramethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) (abbreviation) Organometallic yrrhetin with a pyrimidine skeleton such as [Ir(dmdppm)2(dpm)] Dium complexes and bis(2,3,5-triphenylpyradinate)(dipivaloylmethanato) Iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), bis{4,6- Dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl) )-2-pyrazinyl-κN]phenyl-κC}(2,4-pentanedionato-κ 2 O,O Iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(acac)]) , bis{4,6-dimethyl-2-[5-(2,6-dimethylphenyl)-3-(3,5- Dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,8-dimethyl-4 ,6-nonanzionato-κ 2 O,O') Iridium(III) (Abbreviation: [Ir(dmdp pr-dmp)2(divm)]), bis{4,6-dimethyl-2-[5-(2,6-di Methylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl ₂-κC}(2,2',6,6'-tetramethyl-3,5-heptanedionato-κ) 2 O, O') Iridium(III) (Abbreviation: [Ir(dmdppr-dmp)2(dpm)]) , bis{4,6-dimethyl-2-[5-(2,5-dimethylphenyl)-3-(3,5- Dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-teto Lamethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) (Abbreviation: [ Organic compounds with a pyrazine skeleton, such as Ir(dmdppr-25dmp)2(dpm)]) Examples include metallic iridium complexes. These organometallic iridium complexes offer luminescence efficiency and reliability. It is preferable because it has excellent properties and is also easy to orient molecules.

[0081] In addition to the phosphorescent compounds described above, various phosphorescent materials may be selected and used. stomach.

[0082] As for TADF materials, 2-(biphenyl-4-yl)-4,6-bis(12-phenyl Indoro[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) , 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol [Il-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: P CCzPTzn), 2-[4-(10H-phenoxazine-10-yl)phenyl]-4 ,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5 -phenyl-5,10-dihydrophenazine-10-yl)phenyl]-4,5-diphenyl Nyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl -9H-acridine-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN) ), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfon (Abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acryloid] π-electron-rich forms such as n-9,9'-anthracene]-10'-one (abbreviated as ACRSA) Heterocyclic compounds having both heteroaromatic rings and π-electron-deficient heteroaromatic rings can be used. The heterocyclic compound has a π-electron-rich heteroaromatic ring and a π-electron-deficient heteroaromatic ring. It is preferable because it has high electron transport and hole transport properties. Substances in which electron-deficient heteroaromatic rings are directly bonded to π electron-rich heteroaromatic rings have the properties of a donor and π The acceptor properties of electron-deficient heteroatom rings become stronger, and the energies of the S1 and T1 levels change. - This is particularly preferable because the difference becomes smaller, allowing for efficient acquisition of thermally activated delayed fluorescence. Oh, instead of a π-electron-deficient heteroaromatic ring, there is an aromatic ring bonded with an electron-withdrawing group such as a cyano group. You may also use this.

[0083] 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.

[0084] 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 Lil)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation : PBD), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylph enyl)-1,2,4-triazole (abbreviation: TAZ), 1,3-bis[5-(p-te rt-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl) phenyl]-9H-carbazole (abbreviation: CO11), 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’-(dibenzoth iophen-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: TmP yPB), and heterocyclic compounds having a pyridine skeleton such as these can be mentioned. Among those described above, dia Heterocyclic compounds having a diazine 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 transport properties and also contribute to reducing the driving voltage.

[0085] As materials having hole transport properties, 4,4'-bis[N-(1-naphthyl)-N-phe nylamino]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'-bifluorene-2-yl)-N-phenyl amino]biphenyl (abbreviation: BSPB), 4-phenyl-4'-(9-phenylfluoro ene-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3'-(9 -phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), 4- phenyl-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9-phenyl-9H-ca rubazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-na phthyl)-4'-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4''-(9-phenyl-9 H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 9,9-di methyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)f [phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9 -phenyl-9H-carbazole-3-yl)phenyl]spiro-9,9'-bifluore Compounds having an aromatic amine skeleton such as n-2-amine (abbreviation: PCBASF), and 1, 3-Bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4'-di(N-carbazolyl)benzene Lyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9 -Phenylcarbazole (abbreviation: CzTP), 3,3'-bis(9-phenyl-9H-C) Compounds having a carbazole skeleton such as rubazole (abbreviated as PCCP), and 4,4', 4''-(benzene-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DB) T3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluorene- 9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4- (9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothio Compounds containing a thiophene skeleton, such as Fen (abbreviation: DBTFLP-IV), and 4,4' ,4''-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF) 3P-II), 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl The furan skeleton, such as phenyl dibenzofuran (abbreviation: mmDBFFLBi-II), Examples of compounds that possess this feature include compounds having an aromatic amine skeleton and carba. Compounds with a zole skeleton have good reliability and high hole transport properties, and the driving voltage It is preferable because it also contributes to reduction. In addition to the hole transport materials mentioned above, among various other materials... Therefore, hole transport materials may also be used.

[0086] When using a fluorescent substance as the light-emitting material, use 9-phenyl-3-[4-(10-phenyl Nyl-9-antryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3-[ 4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCP) N), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazo CzPA (abbreviation: CzPA), 7-[4-(10-phenyl-9-antryl)phenyl]- 7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9, 10-Diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]f Ran (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H- Fluoren-9-yl)-biphenyl-4'-yl}-anthracene (abbreviation: FLPPA) Materials having an anthracene skeleton, such as those described above, are preferred. When used as a host material for light-emitting materials, it enables the creation of a light-emitting layer with excellent luminescence efficiency and durability. This is possible, especially with CzPA, cgDBCzPA, 2mBnfPPA, and PCzPA. It exhibits very good characteristics, making it a preferred choice.

[0087] The host material may be a mixture of multiple substances, and the mixed host material When using this method, mix an electron-transporting material with a hole-transporting material. This is preferable. By mixing an electron-transporting material with a hole-transporting material This allows for easy adjustment of the transport properties of the light-emitting layer 113, and also enables simple control of the recombination region. It is possible. The ratio of the content of hole-transporting material to electron-transporting material is the ratio of hole-transporting material. For the material with transportability: the ratio of the material with electron transportability to the other material may be 1:9 to 9:1.

[0088] In addition, an exciplex may be formed between these mixed host materials. The exciplex exhibits emission that overlaps with the wavelength of the absorption band on the lowest energy side of the fluorescent emitter, the phosphorescent emitter, and the TADF material. By selecting a combination that forms an exciplex with such emission, energy transfer becomes smooth and efficient emission can be obtained. In addition, this configuration is a preferable configuration because the driving voltage also decreases.

[0089] Note that the numerical value of a indicating the orientation state of the light-emitting material is not significantly affected by the type and number of the host materials. Therefore, any material can be selected as the host material. Since it has been found that it is not significantly affected by the type and number of the host materials, any material can be selected as the host material.

[0090] The light-emitting layer 113 having the above configuration can be fabricated by co-evaporation using the vacuum evaporation method. At this time, as the chamber atmosphere measured by a quadrupole mass spectrometer (Q-MASS) installed in the evaporation chamber, a condition that is effective is that the ratio of the partial pressure of carbon dioxide to the total pressure in the chamber is larger than that in the atmosphere. In the atmosphere, the ratio (i.e., volume ratio) of the partial pressure of carbon dioxide to the total pressure is about 0.03%. On the other hand, in a vacuum chamber under reduced pressure, by forming the light-emitting layer in a state where the ratio of the partial pressure of carbon dioxide to the total pressure is larger than 0.03%, preferably in a state of 0.1% or more, a light-emitting device in which the orientation state of a of the light-emitting material is 0.2 or less can be fabricated. Note that since carbon dioxide inhibits carrier transportability, the above ratio is preferably 10% or less.

[0091] The electron transport layer 114 is a layer containing a substance that has electron transport properties. In terms of quality, the materials listed above are those with electron transport properties that can be used as host materials. Materials, including those with an anthracene skeleton, can be used.

[0092] Furthermore, a layer for controlling the movement of electron carriers may be provided between the electron transport layer and the light-emitting layer. This involves adding a small amount of a substance with high electron-trapping properties to a material with high electron-transporting properties as described above. This layer adjusts the carrier balance by suppressing the movement of electron carriers. This becomes possible. In such a configuration, electrons penetrate the light-emitting layer, causing emission. It is highly effective in suppressing problems that may arise (for example, a decrease in the lifespan of the device).

[0093] Furthermore, between the electron transport layer 114 and the second electrode 102, electrons are in contact with the second electrode 102. An injection layer 115 may be provided. The electron injection layer 115 may be lithium fluoride (LiF), Alkali metals such as cesium fluoride (CsF) and calcium fluoride (CaF2) or Alkaline earth metals or compounds thereof can be used. For example, those with electron transport properties. A layer made of a substance contains alkali metals, alkaline earth metals, or compounds thereof. A suitable material can be used. Alternatively, an electride may be used in the electron injection layer 115. As an electride, for example, a mixed oxide of calcium and aluminum is used to increase the electron content. Examples include substances added in concentration. Furthermore, the electron injection layer 115 has electron transport properties. By using a material in which alkali metals or alkaline earth metals are contained within a layer of the material. This is more preferable because electron injection from the second electrode 102 is performed more efficiently.

[0094] Alternatively, a charge generation layer 116 may be provided instead of the electron injection layer 115 (Figure 3(B)). The charge generating layer 116 generates holes in the layer adjacent to the cathode side of the layer when an electric potential is applied. This refers to a layer that can inject electrons into the layer in contact with the pole. The charge generation layer 116 is, It includes at least a P-type layer 117. The P-type layer 117 constitutes the hole injection layer 111 described above. It is preferable to form it using the composite materials listed as materials that can be used. Also, the P-type layer 117 is a composite material comprising a film containing the above-mentioned acceptor material and a hole transport material. It may also be constructed by laminating a film containing a material. By applying a potential to the P-type layer 117, Electrons are injected into the electron transport layer 114, and holes are injected into the second electrode 102, which is the cathode, causing the light-emitting element to move. To make.

[0095] In addition to the P-type layer 117, the charge generation layer 116 also includes an electron relay layer 118 and an electron injection buff. It is preferable that one or both of the layers 119 are provided.

[0096] 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.

[0097] 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, carbon dioxide)) (including carbonates such as lithium 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 (oxides, halides, and carbonates) It is possible to use materials with high electron injection capabilities, such as (including)).

[0098] Furthermore, the electron injection buffer layer 119 contains an electron transporting substance and a donor substance. If formed, alkali metals, alkaline earth metals, and rare earth metals are used as donor substances. The genus, and these compounds (alkali metal compounds (oxides such as lithium oxide, halogenated compounds) Substances, 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, In addition to carbonates, tetrathianaphthalene (abbreviation: TTN), nickelosene, and decamene are also included. Organic compounds such as tyrnickerosene can also be used.

[0099] The material forming the second electrode 102 has a small work function (specifically 3.8 eV) The following can be used: metals, alloys, electrically conductive compounds, and mixtures thereof. Specific examples of such cathode materials include lithium (Li) and cesium (Cs). Potassium metals, as well as magnesium (Mg), calcium (Ca), and strontium (Sr) 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 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, Ke Various conductive materials such as indium oxide-tin oxide containing ion or silicon oxide are used in the second These conductive materials can be used as electrodes 102. It is possible to deposit films using dry methods such as the sizing method, inkjet methods, spin coating methods, etc. It can also be formed by a wet process using the sol-gel method, or by using a paste of metal material. It may also be formed using a wet process.

[0100] Furthermore, various methods can be used to form the EL layer 103 other than the light-emitting layer, regardless of whether they are dry or wet methods. The following methods can be used: for example, vacuum deposition, gravure printing, and offset printing. Screen printing, inkjet printing, or spin coating methods may also be used.

[0101] Here, we will explain the method for forming the EL layer 786 using the droplet ejection method, with reference to Figure 4. Figures 4(A) to 4(D) are cross-sectional views illustrating the method for fabricating the EL layer 786.

[0102] First, a conductive film 772 is formed on the planar insulating film 770, and a part of the conductive film 772 is covered. A uni insulating film 730 is formed (see Figure 4(A)).

[0103] Next, liquid droplets from the droplet dispensing device 783 are dispensed onto the exposed portion of the conductive film 772, which is an opening in the insulating film 730. A droplet 784 is dispensed to form a layer 785 containing the composition. The droplet 784 is a composition containing a solvent. It then adheres to the conductive film 772 (see Figure 4(B)).

[0104] The process of dispensing the droplet 784 may also be carried out under reduced pressure.

[0105] Next, the solvent is removed from the layer 785 containing the composition and solidified to form the EL layer 786. Form (see Figure 4(C)).

[0106] The solvent can be removed by either a drying or heating process.

[0107] Next, a conductive film 788 is formed on the EL layer 786 to form the light-emitting element 782 (Figure 4(D )reference).

[0108] By performing the EL layer 786 using the droplet ejection method, the composition can be selectively ejected. Therefore, material waste can be reduced. Also, lithography for processing shapes Because no additional steps are required, the process can be simplified, resulting in lower costs.

[0109] The droplet dispensing method described above refers to a nozzle having a dispensing port for the composition, or one or This term refers to a general category of devices that have means for discharging droplets, such as heads with multiple nozzles.

[0110] Next, the droplet dispensing device used in the droplet dispensing method will be explained using Figure 5. Figure 5 shows the droplet dispensing device. This is a conceptual diagram illustrating the drip dispensing device 1400.

[0111] The droplet dispensing device 1400 has a droplet dispensing means 1403. Unit 3 has head 1405, head 1412, and head 1416.

[0112] Heads 1405 and 1412 are connected to control means 1407, which is a computer By controlling it with the -1410, it is possible to draw on a pre-programmed pattern. can.

[0113] Furthermore, as for the timing of drawing, for example, the marker 1 formed on the substrate 1402 You can use 411 as the reference point. Alternatively, you can determine the reference point by using the outer edge of substrate 1402 as the reference point. It is also acceptable to do so. Here, marker 1411 is detected by imaging means 1404, and image processing means 1 The signal converted to digital in 409 is recognized by computer 1410 and a control signal is issued. It is then sent to the control unit 1407.

[0114] The imaging means 1404 may be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor ( Image sensors using CMOS (CMOS) can be used. The information of the pattern to be formed is stored in the storage medium 1408, and this information Based on this, a control signal is sent to the control means 1407, and the individual heads 1 of the droplet ejection means 1403 Heads 405, 1412, and 1416 can be controlled individually. Dispensing material The material is supplied from material supply sources 1413, 1414, and 1415 via piping. It is supplied to head 1405, head 1412, and head 1416, respectively.

[0115] The interior of heads 1405, 1412, and 1416 is as shown by the dotted line 1406. It has a structure that includes a space for filling with liquid material and a nozzle that serves as the discharge port. However, head 1412 has a similar internal structure to head 1405. By providing nozzles of different sizes on head 1412, different materials can be drawn simultaneously with different widths. It is possible to eject and draw with multiple types of luminescent materials using a single head. It is possible to use multiple nozzles to improve throughput when drawing over a wide area. The same material can be ejected and drawn simultaneously. When using a large substrate, head 1405 Heads 1412 and 1416 move on the substrate in the direction of the X, Y, and Z arrows shown in Figure 5. It allows for free scanning and drawing of areas, and the same pattern can be printed on a single substrate. Multiple drawings are possible.

[0116] Furthermore, the process of dispensing the composition may be carried out under reduced pressure. The substrate is heated during dispensing. This may also be done. After the composition is extruded, one or both of the following steps are performed: drying and / or calcination. Drying and calcination steps Both processes involve heat treatment, but their purpose, temperature, and time differ. The drying and firing processes are carried out under normal pressure or reduced pressure using laser irradiation, instantaneous heat annealing, or heating. This is done using a furnace or similar device. The timing and number of times this heat treatment is performed are not particularly limited. It is not possible. In order to carry out the drying and firing processes properly, the temperature at that time depends on the material of the substrate and the assembly. It depends on the properties of the resulting product.

[0117] As described above, the EL layer 786 can be fabricated using a droplet ejection device.

[0118] When preparing the EL layer 786 using a droplet dispensing device, various organic solvents are used to create the coating composition. It is possible to create an object. An organic solvent that can be used in the above composition is benz N, Toluene, Xylene, Mesitylene, Tetrahydrofuran, Dioxane, Ethanol, methanol, n-propanol, isopropanol, n-butanol, t-butanol, Acetonitrile, dimethyl sulfoxide, dimethylformamide, chloroform, methyl Various organic solvents such as carbon chloride, carbon tetrachloride, ethyl acetate, hexane, and cyclohexane It can be used. In particular, low-polarity benzene, toluene, xylene, mesitylene, etc. By using a lenzen derivative, it is possible to create a solution of a suitable concentration, and also to incorporate it into the ink. This is preferable because it prevents the material being produced from degrading due to oxidation, etc. Considering the uniformity of the material and the uniformity of the film thickness, it is preferable that the boiling point be 100°C or higher. Luene, xylene, and mesitylene are even more preferred.

[0119] Furthermore, the above configuration can be appropriately combined with other configurations in this embodiment.

[0120] The electrodes can also be formed using a wet method with the sol-gel method, or they can be formed using a metallic base material. It may also be formed by a wet method using a t. Alternatively, dry methods such as sputtering or vacuum deposition may be used. It may also be formed using [a specific method / tool].

[0121] The light emitted from the light-emitting element is from either the first electrode 101 or the second electrode 102. It is extracted to the outside through both. Therefore, the first electrode 101 or the second electrode 102 Either one or both of these are formed from a translucent electrode.

[0122] 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 close together The first electrode 101 and the second electrode are positioned so as to suppress quenching caused by contact. A configuration is preferred in which a light-emitting region is provided at a location away from 102 where holes and electrons recombine.

[0123] Furthermore, the hole transport layer and electron transport layer in contact with the light-emitting layer 113, and especially the regeneration in the light-emitting layer 113, The carrier transport layer in contact with the region closer to the convergence region transfers energy from excitons generated in the light-emitting layer. In order to suppress movement, the band gap is such that the luminescent material constituting the luminescent layer or the luminescent layer A substance having a band gap larger than the band gap of the luminescent central substance it contains. It is preferable to configure it as such.

[0124] Next, a light-emitting element with a configuration in which multiple light-emitting units are stacked (stacked element, tandem light-emitting element) The configuration of the element (also called a light-emitting element) will be explained with reference to Figure 3(C). This light-emitting element is an anode This is a light-emitting element having multiple light-emitting units between the cathode and the element. One light-emitting unit is It has a similar configuration to the EL layer 103 shown in Figure 3(A) or Figure 3(B). In other words, Figure 3( The light-emitting element shown in A) or Figure 3(B) is a light-emitting element having one light-emitting unit. The light-emitting element shown in Figure 3(C) is a light-emitting element having multiple light-emitting units. can.

[0125] In Figure 3(C), a first light-emitting element is placed between the first electrode 501 and the second electrode 502. The knit 511 and the second light-emitting unit 512 are stacked, and the first light-emitting unit 511 A charge generation layer 513 is provided between the first electrode and the second light-emitting unit 512. Electrodes 501 and 502 correspond to the first electrode 101 and the second electrode in Figure 3(A), respectively. This corresponds to 102, and the same explanation as described in Figure 3(A) can be applied. Furthermore, even if the first light-emitting unit 511 and the second light-emitting unit 512 have the same configuration, they are different. The configuration is also acceptable.

[0126] When a voltage is applied to the first electrode 501 and the second electrode 502, the charge generation layer 513 generates It has the function of injecting electrons into one light-emitting unit and holes into the other light-emitting unit. That is, in Figure 3(C), the potential of the first electrode is higher than the potential of the second electrode. When a voltage is applied in such a manner, the charge generation layer 513 generates electrons in the first light-emitting unit 511. Any method that injects a substance and injects holes into the second light-emitting unit 512 is acceptable.

[0127] The charge generation layer 513 is formed with the same configuration as the charge generation layer 116 described in Figure 3(B). It is preferable that the composite material of organic compounds and metal oxides has good carrier implantation and carrier transport properties. Due to its excellent transmission properties, it can achieve low-voltage and low-current operation. When the anode side of the knit is in contact with the charge generation layer 513, the charge generation layer 513 emits light. Since it can also serve as a hole injection layer in knitted materials, the light-emitting unit is equipped with a hole injection layer. It is not necessary to set one up.

[0128] Furthermore, if an electron injection buffer layer 119 is provided, the layer is located in the anode-side light-emitting unit. In order to fulfill the role of an electron injection layer, the electron injection layer is not necessarily formed on top of the light-emitting unit. There's no need to do that.

[0129] Figure 3(C) illustrates a light-emitting element having two light-emitting units, but what if there are three or more? The same principle can be applied to light-emitting devices formed by stacking multiple light-emitting units. As in the form of a light-emitting element, multiple light-emitting units are placed between a pair of electrodes in a charge generation layer 51 By dividing and arranging the elements in a 3-part system, high-brightness illumination is possible while maintaining a low current density, and furthermore... This enables the creation of long-life elements. Furthermore, it allows for low-voltage operation and enables the creation of light-emitting devices with low power consumption. It is possible.

[0130] 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 the 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. By doing so, it is easy to obtain a light-emitting element that emits white light as a whole.

[0131] <<Micro-optical resonator (microcavity) structure>> A light-emitting element having a microcavity structure has the above pair of electrodes as a reflective electrode and a semi-transparent electrode. It is obtained by constructing a semi-reflective electrode. The reflective electrode and the semi-transmissive / semi-reflective electrode are as described above. This corresponds to the first electrode and the second electrode. There is at least one space between the reflective electrode and the semitransmissive / semi-reflective electrode. It also has an EL layer, and the EL layer has at least an emissive layer that forms an emissive region.

[0132] 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. The reflective electrode preferably has a visible light reflectivity of 40% to 100%. Or it is 70% to 100%, and its resistivity is 1 × 10⁻⁶ -2 Those that are less than or equal to Ωcm Furthermore, the semi-transparent / semi-reflective electrode has a visible light reflectance of 20% to 80%, preferably. It is between 40% and 70%, and its resistivity is 1 × 10⁻⁶ -2 It should be less than or equal to Ωcm.

[0133] Furthermore, the light-emitting element has a thickness of the transparent conductive film, the aforementioned composite material, carrier transport material, etc. By changing this, the optical distance between the reflective electrode and the semitransmissive / semi-reflective electrode can be altered. This enhances the light of resonant wavelengths between the reflective electrode and the semitransmissive / semi-reflective electrode, and It can attenuate light of wavelengths that do not vibrate.

[0134] Furthermore, of the light emitted from the light-emitting layer, the light that is reflected back by the reflective electrode (the first Reflected light is a large amount of light that is directly incident on the semi-transmitting / semi-reflective electrodes from the light-emitting layer (first incident light). To avoid interference, the optical distance between the reflective electrode and the light-emitting layer is (2n-1)λ / 4 (where n is It is preferable to adjust it to a natural number greater than or equal to 1 (where λ is the wavelength of the color to be amplified). This will result in By aligning the phase of the reflected light from 1 and the first incident light, the light emitted from the light-emitting layer can be further amplified. Cut.

[0135] Furthermore, in the above configuration, even if the EL layer has a structure with multiple light-emitting layers, a single light The structure may also have an optical layer, for example, in combination with the tandem light-emitting element configuration described above. Furthermore, multiple EL layers are provided on a single light-emitting element, with a charge generation layer in between, and each EL layer has a single This may also be applied to configurations that form several or more light-emitting layers.

[0136] ≪Light-emitting device≫ A light-emitting device according to one aspect of the present invention will be described with reference to Figure 6. Figure 6(A) shows the light emission. Figure 6(B) is a top view showing the apparatus, and is a cross-sectional view obtained by cutting Figure 6(A) along AB and CD. This light-emitting device controls the light emission of the light-emitting element, and the drive circuit section shown by the dotted line... (Source line drive circuit) 601, pixel section 602, drive circuit section (gate line drive circuit) 603 It includes. Also, 604 is the sealing substrate, and 605 is the sealing material, and it is surrounded by the sealing material 605. The inside of this structure is a space of 607.

[0137] The routing wiring 608 is connected to the source line drive circuit 601 and the gate line drive circuit 603. FPC (Flexible Printed Circuit) is a wiring used to transmit signals and serves as an external input terminal. (Lindt Circuit) Video signal, clock signal, start signal, reset signal from 609 Receives, etc. Note that only FPC is shown in the diagram here, but this FPC has print A circuit board (PWB) may be attached. The light-emitting device in this specification includes light-emitting This includes not only the device itself, but also the state in which the FPC or PWB is attached to it. do.

[0138] Next, the cross-sectional structure will be explained using Figure 6(B). The drive circuit is located on the element substrate 610. A section and a pixel section are formed, but here, the source line drive circuit 601 is the drive circuit section. This shows one of the pixels in the pixel section 602.

[0139] The source line drive circuit 601 consists of an n-channel FET 623 and a p-channel FET 62 A CMOS circuit is formed by combining it with 4. In addition, the drive circuit is a variety of CMOS circuits It may also be formed using PMOS or NMOS circuits. In this embodiment, the substrate The image above shows a driver integrated with a drive circuit, but this is not always necessary; the drive circuit can be... It can also be formed on an external surface rather than on the substrate.

[0140] Furthermore, the pixel section 602 includes a switching FET 611 and a current control FET 612 and It is formed by a plurality of pixels, including a first electrode 613 electrically connected to the drain. However, it is not limited to this, and the pixel section may be a combination of three or more FETs and a capacitive element. That's good too.

[0141] There are no particular limitations on the type and crystallinity of semiconductors used in FETs; amorphous semiconductors are also used. Alternatively, crystalline semiconductors may be used. Examples of semiconductors used in FETs include the first By using Group 3 semiconductors, Group 14 semiconductors, compound semiconductors, oxide semiconductors, and organic semiconductor materials... This is possible, but it is particularly preferable to use an oxide semiconductor. Examples of the oxide semiconductor include For example, In-Ga oxide and In-M-Zn oxide (where M is Al, Ga, Y, Zr, La, C). Examples include e, or Nd). Furthermore, an energy gap of 2eV or more is preferred. By using an oxide semiconductor material with a voltage of 2.5 eV or higher, and more preferably 3 eV or higher, the tra This configuration is preferable because it can reduce the off-current of the inverter.

[0142] Furthermore, an insulator 614 is formed covering the end of the first electrode 613. Here, It can be formed by using a photosensitive acrylic resin film of type D.

[0143] Furthermore, in order to ensure good coverage, the upper or lower end of the insulator 614 has a curvature. A curved surface is formed. For example, as the material for the insulator 614, a positive-type photosensitive material is used. When krill is used, the radius of curvature (0.2 μm to 3 μm) is applied only to the upper end of the insulator 614. It is preferable to give it a curved surface. Also, as the insulator 614, a negative-type photosensitive resin Either a positive-type photosensitive resin or a similar type can be used.

[0144] An EL layer 616 and a second electrode 617 are formed on the first electrode 613, respectively. These are the first electrode 101 and EL layer 1, respectively, as explained in Figure 3(A) or Figure 3(B). 03 and the second electrode 102 or the first electrode 501 as described in Figure 3(C), EL layer (511 This corresponds to electrodes 513 through 513 and the second electrode 502.

[0145] The EL layer 616 preferably contains an organometallic complex. This organometallic complex emits light. It is preferable to use it as the luminescence central material in the layer.

[0146] 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 element substrate 610, the sealing substrate 604, and the sealing material 605. The structure is equipped with child 618. Furthermore, the space 607 is filled with a filler material. In addition to cases where an inert gas (such as nitrogen or argon) is filled, it is also filled with sealant 605. In some cases, this can occur. If a recess is formed in the encapsulating substrate and a desiccant is placed there, deterioration due to the effects of moisture can occur. This configuration is preferable because it can suppress oxidation.

[0147] It is preferable to use epoxy resin or glass frit for the sealant 605. These materials should preferably be as impermeable to moisture and oxygen as possible. In addition to glass substrates and quartz substrates, FRP is used as a material for substrate 610 and encapsulating substrate 604. Fiber Reinforced Plastics, PVF (Polyvinyl Floral Fiber) A plastic substrate made of polyester or acrylic can be used.

[0148] For example, in this specification, transistors and light-emitting elements are formed using various substrates. It is possible to do so. The type of circuit board is not limited to a specific one. An example of such a circuit board is... For example, semiconductor substrates (e.g., single crystal substrates or silicon substrates), SOI substrates, glass substrates, Quartz substrate, plastic substrate, metal substrate, stainless steel substrate, stainless steel • Substrates with foil, tungsten substrates, substrates with tungsten foil, flexible Examples include substrates, laminated films, paper containing fibrous materials, or base films. Examples of substrates include barium borosilicate glass, aluminoborosilicate glass, or so Examples include 1-Dalime glass. Flexible substrates, laminated films, base films, etc. Examples include the following: For example, polyethylene terephthalate (PET). , represented by polyethylene naphthalate (PEN) and polyethersulfone (PES) There are plastics that are made of acrylic, for example. Examples include polytetrafluoroethylene (PTFE), polypropylene, and polyethylene. Examples include polyester, polyvinyl fluoride, or polyvinyl chloride. Alternatively, as an example, These include rhamides, polyimides, aramids, epoxy, inorganic vapor-deposited films, or paper. In particular, the manufacturing of transistors using semiconductor substrates, single crystal substrates, or SOI substrates. Therefore, variations in characteristics, size, or shape are small, and current capacity is high. It is possible to manufacture very small transistors. Circuits can be made with such transistors. This configuration allows for lower power consumption or higher circuit integration.

[0149] Furthermore, a flexible substrate is used as the substrate, and transistors and light-emitting elements are directly mounted on the flexible substrate. A release layer may be formed between the substrate and the transistor, or between the substrate and the light-emitting element. It may be provided. The release layer is applied to the substrate after the semiconductor device has been partially or completely completed on it. They can be separated and used to transfer to other substrates. In this case, the transistors are heat-resistant. It can be transferred to substrates with inferior properties or flexible substrates. Furthermore, the aforementioned release layer can be, for example, tungsten. The configuration of an inorganic film layered structure of a stainless steel film and a silicon oxide film, and organic materials such as polyimide on a substrate. A structure in which a resin film is formed can be used.

[0150] In other words, transistors and light-emitting elements are formed using one substrate, and then transistors are transferred to another substrate. The transistors and light-emitting elements may be relocated and placed on a different substrate. An example of a substrate on which transistors or light-emitting elements are transposed is the one on which the above-mentioned transistors are formed. In addition to substrates that can be used, paper substrates, cellophane substrates, aramid film substrates, and polyimide substrates are also available. Film substrates, stone substrates, wood substrates, cloth substrates (natural fibers (silk, cotton, hemp), synthetic fibers (nails) (Iron, polyurethane, polyester) or regenerated fibers (acetate, cupro, rayon) These include yon, recycled polyester, etc., leather substrates, or rubber substrates. By using a substrate, it is possible to form transistors with good characteristics and transistors with low power consumption. It is possible to form a tangible structure, manufacture a durable device, provide heat resistance, reduce weight, or make it thinner. ru.

[0151] Figure 7 shows a light-emitting element that emits white light, and a colored layer (color filter), etc. An example of a light-emitting device that has been made full-color by [method] is shown. Figure 7(A) shows substrate 1001, underlay insulation Edge film 1002, gate insulating film 1003, gate electrodes 1006, 1007, 1008, 1 The interlayer insulating film 1020, the second interlayer insulating film 1021, the peripheral portion 1042, the pixel portion 1040, Drive circuit section 1041, first electrodes 1024W, 1024R, 1024G, 10 24B, partition wall 1025, EL layer 1028, second electrode 1029 of light-emitting element, sealing substrate 10 31. The sealing material 1032 and other components are shown in the illustration.

[0152] Furthermore, in Figure 7(A), the colored layers (red colored layer 1034R, green colored layer 1034G, blue) are shown. The colored layer (1034B) is provided on the transparent substrate (1033). In addition, the black layer (black mat) A further component (Tricks) 1035 may be provided. A transparent substrate having a colored layer and a black layer. 1033 is aligned and fixed to the substrate 1001. Note that the colored layer and the black layer are O It is covered with a supercoat layer.

[0153] Furthermore, in Figure 7(A), the light-emitting layer allows light to escape to the outside without passing through the colored layer, and the colored layer of each color There is a light-emitting layer that passes through the color layer and emits light to the outside. Light that does not pass through the color layer is white, and light that passes through the color layer is white. Since passing light is red, blue, and green, images can be represented using pixels of these four colors.

[0154] Figure 7(B) shows the colored layers (red colored layer 1034R, green colored layer 1034G, blue colored layer A color layer (1034B) is formed between the gate insulating film 1003 and the first interlayer insulating film 1020. An example is shown. As shown, the colored layer is provided between the substrate 1001 and the sealing substrate 1031. You can.

[0155] Furthermore, in the light-emitting device described above, light is taken to the substrate 1001 side on which the FET is formed. Although the light-emitting device was designed with a bottom-emission structure, the light-emitting element was directed towards the sealing substrate 1031. It can also be used as a light-emitting device with an extraction structure (top emission type). Top emission type Figure 8 shows a cross-sectional view of the light-emitting device. In this case, the substrate 1001 is a substrate that does not transmit light. This is possible. Until the connecting electrode that connects the FET and the anode of the light-emitting element is fabricated, the bottom It is formed in the same way as an emission-type light-emitting device. Then, the third interlayer insulating film 1037 is attached to the electrode. It is formed covering 1022. This insulating film may also play a planarizing role. Third interlayer The insulating film 1037 is formed using the same material as the second interlayer insulating film, as well as various other materials. It is possible.

[0156] The first electrodes 1024W, 1024R, 1024G, and 1024B of the light-emitting element are positive here. This is referred to as the pole, but it can also be the cathode. Furthermore, top-emission type light emission as shown in Figure 8 is also possible. In the case of a device, it is preferable that the first electrode be a reflective electrode. The configuration of the EL layer 1028 is , EL layer 103 in Figure 3(A) or Figure 3(B) or EL layer (511 to 51) in Figure 3(C) The device has the configuration described in 3), and the element structure is such that white light emission can be obtained. .

[0157] In the top emission structure shown in Figure 8, the colored layer (red colored layer 1034R, green colored layer) The sealing is performed using a sealing substrate 1031 having a colored layer 1034G and a blue colored layer 1034B. This can be done. The encapsulating substrate 1031 has a black layer positioned between the pixels. A matrix 1035 may be provided. Colored layer (red colored layer 1034R, green colored layer Layer 1034G, the blue colored layer 1034B, and the black layer are covered by an overcoat layer. It is acceptable to include it. Furthermore, the sealing substrate 1031 shall be a light-transmitting substrate.

[0158] 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 three colors (red, green, and blue) or four colors (red, green, blue, and yellow).

[0159] Figure 9 shows a passive matrix type light-emitting device, which is one embodiment of the present invention. Figure A) is a perspective view showing the light-emitting device, and Figure 9(B) is a cross-sectional view of Figure 9(A) cut along the X and Y lines. In Figure 9, on the substrate 951, there is an EL layer 955 between electrode 952 and electrode 956. A is provided. The end of the electrode 952 is covered with an insulating layer 953. And the insulating layer 9 A partition layer 954 is provided on 53. The side walls of the partition layer 954 are close to the substrate surface. Consequently, it has a slope such that the distance between one side wall and the other side wall becomes narrower. The cross-section of the partition layer 954 in the short-side direction is trapezoidal, and the base (similar to the surface direction of the insulating layer 953) The side facing the direction of the insulating layer 953 (the side in contact with the insulating layer 953) is the upper side (the side in the same direction as the plane of the insulating layer 953) It is shorter than the side that faces the opposite direction and does not come into contact with the insulating layer 953. In this way, the partition layer 954 is provided. This prevents defects in the light-emitting element caused by static electricity, etc.

[0160] The light-emitting device described above uses a large number of tiny light-emitting elements arranged in a matrix, which are used as pixels. Since each part can be controlled by an FET formed in the section, the display that represents the image This is a light-emitting device that can be suitably used as a device.

[0161] Lighting equipment A lighting device according to one aspect of the present invention will be described with reference to Figure 10. Figure 10(B) shows the lighting Figure 10(A) is a top view of the apparatus, and Figure 10(B) is a cross-sectional view of ef.

[0162] The lighting device has a first electrode 401 formed on a translucent substrate 400 which serves as a support. This has been done. The first electrode 401 corresponds to the first electrode 101 in Figures 3(A) and (B). When light is extracted from the first electrode 401 side, the first electrode 401 is made of a light-transmitting material. To form more.

[0163] A pad 412 for supplying voltage to the second electrode 404 is formed on the substrate 400.

[0164] An EL layer 403 is formed on the first electrode 401. The EL layer 403 is shown in Figure 3(A). This corresponds to the EL layer 103 or EL layer (511 to 513) of (B) and (C). Please refer to the relevant description for details on these configurations.

[0165] The second electrode 404 is formed by covering the EL layer 403. The second electrode 404 is shown in Figure 3(A). This corresponds to the second electrode 102 of (B). When the light emission is taken from the first electrode 401 side, The second electrode 404 is formed from a material with high reflectivity. The second electrode 404 is attached to the pad 41 By connecting to 2, voltage is supplied.

[0166] A light-emitting element is formed by the first electrode 401, the EL layer 403, and the second electrode 404. The light-emitting element is sealed by fixing the sealing substrate 407 using sealing materials 405 and 406. The lighting device is completed by doing this. Either sealing material 405 or 406 is acceptable. Also, a desiccant should be mixed into the inner sealing material 406 (not shown in Figure 10(B)). This also allows for the absorption of moisture, leading to improved reliability.

[0167] 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.

[0168] ≪Electronic equipment≫ An example of an electronic device according to one aspect of the present invention will be described. As an electronic device, for example, tele... Vision equipment (also called television or television receiver), computer-based, etc. Nita, digital cameras, digital video cameras, digital photo frames, Mobile phones (also called mobile phones or mobile phone devices), portable game consoles, personal digital assistants, and audio equipment. Examples include playback devices and large game machines such as pachinko machines. Specific examples of these electronic devices The following is shown.

[0169] Figure 11(A) shows an example of a television system. The television system consists of a housing 71 The display unit 7103 is incorporated into 01. Also, here the stand 7105 is used to form the enclosure. This shows the configuration supporting the body 7101. The display unit 7103 can display images. This is possible, and the display unit 7103 is configured by arranging light-emitting elements in a matrix.

[0170] 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.

[0171] 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.

[0172] Figure 11(B1) is a computer, consisting of a main unit 7201, a casing 7202, a display unit 7203, Includes keyboard 7204, external connection port 7205, pointing device 7206, etc. Furthermore, this computer uses a matrix arrangement of light-emitting elements for the display unit 7203. It is created by having [something]. The computer in Figure 11(B1) is like Figure 11(B2) It may be in any form. The computer in Figure 11(B2) has a keyboard 7204, a pointer A second display unit 7210 is provided instead of the display device 7206. The unit 7210 is a touch panel, and the inputs displayed on the second display unit 7210 Input can be performed by operating the display with a finger or a special pen. Also, the second table The display unit 7210 can display not only input images but also other images. The display unit 7203 may also be a touch panel. The two screens are connected by a hinge. This also prevents problems such as scratches or damage to the screen during storage or transport. It can be stopped.

[0173] Figures 11(C) and (D) show an example of a personal digital assistant (PDA). The PDA has a housing of 740. In addition to the display unit 7402 incorporated into 1, there are also operation buttons 7403, an external connection port 7404, It is equipped with speaker 7405, microphone 7406, etc. Furthermore, the portable information terminal uses a light-emitting element. It has a display unit 7402 made by arranging the elements in a matrix.

[0174] The portable information terminals shown in Figures 11(C) and (D) can be accessed by touching the display unit 7402 with a finger or the like. It can also be configured to allow information to be entered. In this case, you can make a phone call, or Operations such as composing an email are performed by touching the display unit 7402 with a finger or other object. It is possible.

[0175] 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 mainly 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.

[0176] For example, when making a phone call or composing an email, the display unit 7402 is used for text input. In this case, the primary text input mode should be used, 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.

[0177] Furthermore, the mobile information terminal has sensors that detect tilt, such as a gyroscope and an accelerometer. By providing a detection device, the orientation of the mobile phone (vertical or horizontal) is determined, and the display unit 7402 The screen display can be set to switch automatically.

[0178] 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.

[0179] 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.

[0180] 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.

[0181] Furthermore, the above-mentioned electronic device can be used by appropriately combining the configurations shown in this specification. .

[0182] Furthermore, it is preferable to use a light-emitting element according to one embodiment of the present invention in the display unit. The light-emitting element is It is possible to create a light-emitting element with good light efficiency. Furthermore, it is possible to create a light-emitting element with a low driving voltage. Therefore, it is possible to do so. For this reason, an electronic device including a light-emitting element according to one aspect of the present invention has low power consumption. It can be made into a small electronic device.

[0183] Figure 12 shows an example of a liquid crystal display device in which a light-emitting element is applied as a backlight. The liquid crystal display device consists of a housing 901, a liquid crystal layer 902, a backlight unit 903, and a housing 9 The liquid crystal layer 902 has 04 and is connected to the driver IC 905. A light-emitting element is used in terminal 903, and current is supplied to it via terminal 906.

[0184] It is preferable to use an light-emitting element according to one aspect of the present invention, and the light-emitting element is a liquid crystal. By applying it to the backlight of the display device, a backlight with reduced power consumption can be obtained. obtained.

[0185] FIG. 13 is an example of an electric stand according to one aspect of the present invention. The electric stand shown in FIG. 13 has a housing 2001 and a light source 2002, and an illumination device using a light emitting element as the light source 2002 is used.

[0186] FIG. 14 is an example of an indoor lighting device 3001. It is preferable to use a light emitting element according to one aspect of the present invention for the lighting device 3001. is preferably used.

[0187] An automobile according to one aspect of the present invention is shown in FIG. 15. The automobile has light emitting elements mounted on the windshield and the dashboard. The display areas 5000 to 5005 are display areas provided using light emitting elements. It is preferable to use a light emitting element according to one aspect of the present invention. As a result, since the display areas 5000 to 5005 can suppress power consumption, they are suitable for in-vehicle use. preferably, and are suitable for in-vehicle use.

[0188] The display area 5000 and the display area 5001 are display devices provided on the windshield of the automobile and using light emitting elements. By manufacturing this light emitting element with electrodes having translucency for the first electrode and the second electrode, a so-called see-through type display device in which the opposite side can be seen through can be obtained. In the case of a see-through type display, even if it is installed on the windshield of the automobile, it can be installed without obstructing the view. When providing a transistor or the like for driving, it is preferable to use a transistor having translucency, such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor. electrodes, a so-called see-through type display device in which the opposite side can be seen through can be obtained. In the case of a see-through type display, even if it is installed on the windshield of the automobile, it can be installed without obstructing the view. When providing a transistor or the like for driving, it is preferable to use a transistor having translucency, such as an organic transistor made of an organic semiconductor material or a transistor using an oxide semiconductor.

[0189] Display area 5002 is a display device that uses light-emitting elements provided on the pillar portion. Area 5002 displays images from an imaging device installed on the vehicle body, thereby showing the pillars It can compensate for the obstructed view. Also, similarly, it is provided on the dashboard. The display area 5003 is an imaging means located on the outside of the vehicle, which captures the view obstructed by the vehicle body. By displaying images from various sources, blind spots can be compensated for, and safety can be enhanced. By displaying images that complement the missing parts, safety checks can be performed more naturally and without any sense of incongruity. It is possible.

[0190] Display areas 5004 and 5005 display navigation information, speedometer, engine speed, and mileage. It can provide various information such as fuel level, gear status, air conditioning settings, and more. 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.

[0191] Figures 16(A) and 16(B) show examples of foldable tablet devices. 6(A) is in the open state, and the tablet terminal consists of the housing 9630 and the display unit 9631a Display unit 9631b, display mode switching switch 9034, power switch 9035, It has a power mode selector switch 9036, a fastener 9033, and an operation switch 9038. The tablet terminal is equipped with a light-emitting device according to one aspect of the present invention as a display unit. It is manufactured by using it in either or both of the 9631a and the display unit 9631b.

[0192] The display unit 9631a can be partially designated as a touch panel area 9632a, and the display will be Data can be entered by touching the operation key 9637. Note that the display unit 963 In 1a, as an example, one half of the area has a display-only function, and the other half of the area The diagram shows a configuration that includes touch panel functionality, but is not limited to this configuration. Display unit 963 The entire area of ​​1a may also be configured to have touch panel functionality. For example, the display unit 96 The entire surface of 31a is used as a touch panel with keyboard buttons, and the display unit 9631b is displayed. It can be used as a screen.

[0193] In addition, in the display unit 9631b, similar to the display unit 9631a, one of the display units 9631b The section can be designated as the touch panel area 9632b. Additionally, the touch panel keyboard... By touching the location where the display switch button 9639 is displayed with your finger or stylus, Keyboard buttons can be displayed on the display unit 9631b.

[0194] Furthermore, if you touch the touch panel area 9632a and the touch panel area 9632b simultaneously... You can also input "chi".

[0195] Additionally, the display mode switch 9034 selects the display orientation, such as portrait or landscape. You can switch between modes, such as black and white or color display. Power saving mode switching. Switch 9036 is detected by an optical sensor built into the tablet device when it is in use. The display brightness can be optimized according to the amount of light. In addition to sensors, other detection devices such as gyroscopes, accelerometers, and other sensors that detect tilt It may be built-in.

[0196] Furthermore, Figure 16(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 the display may also differ. For example, one display panel can provide a higher resolution display than the other. You can also use "ru".

[0197] Figure 16(B) shows the closed state, and in this embodiment, the tablet terminal has a casing. Body 9630, solar cell 9633, charge / discharge control circuit 9634, battery 9635, DCD An example is shown that includes a C converter 9636. Note that in Figure 16(B), the charge / discharge control circuit 963 As an example of 4, consider a configuration having a battery 9635 and a DC-DC converter 9636. It is showing.

[0198] Note that the tablet device is foldable, so when not in use, the casing 9630 is closed. This can be done. Therefore, the display units 9631a and 9631b can be protected. We can provide tablet devices that are highly durable and reliable from a long-term use perspective.

[0199] In addition, the tablet devices shown in Figures 16(A) and 16(B) are also available in various forms. Functions to display information (still images, videos, text images, etc.), calendar, date or time, etc. A function that displays information on the display unit, and a touch input operation or editing of the information displayed on the display unit. It has input capabilities, and functions to control processing through various software (programs), etc. It is possible.

[0200] The touch panel is powered by a solar cell 9633 mounted on the surface of the tablet device. 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, efficient charging of the battery 9635 This configuration is preferable because it allows for the following actions to be performed.

[0201] Furthermore, the configuration and operation of the charge / discharge control circuit 9634 shown in Figure 16(B) are shown in Figure 16( A block diagram is shown and explained in C). Figure 16(C) shows solar cell 9633, battery 9 635, 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 963 6. Converter 9638 and switches SW1 to SW3 control the charge and discharge as shown in Figure 16(B). This corresponds to circuit 9634.

[0202] First, let's explain an example of how the solar cell 9633 operates when generating electricity using ambient light. The electricity generated by the solar panel is converted to DC to provide the voltage needed to charge the 9635 battery. The DC converter 9636 performs either a boost or a buck. Then, the display unit 9631 operates as follows: When power charged by solar cell 9633 is used, turn on switch SW1. The converter 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 9635 battery.

[0203] 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.

[0204] Furthermore, if the above-mentioned display unit 9631 is included, it is a tablet terminal with the shape shown in Figure 16. Not limited to this.

[0205] Figures 17(A) to (C) also show a foldable portable information terminal 9310. Figure 17 (A) shows the portable information terminal 9310 in its unfolded state. Figure 17(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 17(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.

[0206] 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]

[0207] In this embodiment, a light-emitting element (light-emitting element 1) according to one embodiment of the present invention with good efficiency is used. A light-emitting element for measurement (light-emitting element 1) having a light-emitting layer with a configuration that minimizes front brightness. We will explain in detail the results of fabricating (-1) and determining a. Figure 18 shows the element structure of the light-emitting device. This will be shown.

[0208] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0209] [ka]

[0210] (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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0211] 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.

[0212] 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 was left for approximately 30 minutes. It was allowed to cool.

[0213] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and the other are used in a weight ratio of 4:2 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing a 10 nm layer in this manner.

[0214] Next, on the hole injection layer 111, 4-phenyl-4'-(9, represented by the above structural formula (ii) -phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) film thickness 3 A hole transport layer 112 was formed by depositing the material to a thickness of 0 nm.

[0215] Next, the 7-[4-(10-phenyl-9-antriol] represented by the above structural formula (iii) is shown. [Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) The above structural formula (iv) represents N,N'-bis(3-methylphenyl)-N,N'-bis [3-(9-phenyl-9H-fluoren-9-yl)phenyl]-pyrene-1,6-di Amine (abbreviation: 1,6mMemFLPAPrn) and cgDB in a weight ratio of 1:0.03 (=cgDB) A 15nm co-deposited light-emitting layer 11 (CzPA:1,6mMemFLPAPrn) was formed using CzPA:1,6mMemFLPAPrn). 3 was formed. Note that when forming the light-emitting layer 113 (during deposition), Q- was provided in the deposition chamber. In MASS measurement, the total pressure is 1 × 10⁻⁶ -4 It fluctuated around Pa and was detected with a molecular weight of 44. The partial pressure of carbon dioxide is 6 × 10 -7 It remained around Pa. That is, the total during deposition The ratio of the partial pressure of carbon dioxide to the total pressure was approximately 0.6%. Thus, the total pressure during deposition The ratio of the partial pressure of carbon dioxide to the total pressure is greater than 0.03%, specifically 0.1% or less. It is important that it is above. Note that Q-MASS can only detect gases with molecular weights of 1 to 200. Because it is not present, the total pressure of Q-MASS is not exactly the same as the actual total pressure inside the chamber. Furthermore, the partial pressure of gaseous components with molecular weights exceeding 200 is negligibly small, therefore, all total pressures Similar results can be obtained using [another method].

[0216] Subsequently, cgDBCzPA is deposited onto the light-emitting layer 113 to a thickness of 20 nm, Bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (v), is applied to a film thickness of 15 nm. The electron transport layer 114 was formed by depositing the material in such a manner.

[0217] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 1 of this embodiment was fabricated by forming a second electrode 102 by vapor deposition.

[0218] (Method for fabricating light-emitting element 1-1) After the electron injection layer 115 of the above-mentioned light-emitting element 1-1 is formed, the above-mentioned structural formula (vi) Copper phthalocyanine (abbreviated as CuPc), represented by [formula], is deposited to a thickness of 2 nm and then electron relay is performed. - A layer 118 is formed, and DBT3P-II and molybdenum(VI) oxide are mixed in a weight ratio of 2:1 (= A 60nm co-deposited layer (DBT3P-II: molybdenum oxide) was formed to create a P-type layer 117. This was done, and a film thickness adjustment layer was formed.

[0219] The element structures of light-emitting element 1 and light-emitting element 1-1 are summarized in the table below.

[0220] [Table 1]

[0221] The light-emitting element 1 and light-emitting element 1-1 are placed in a glove box in 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, the light-emitting element 1 and the light-emitting element are subjected to UV treatment and heat treatment at 80°C for 1 hour. Measurements were taken to determine the initial characteristics of 1-1. The measurements were performed in an atmosphere maintained at 25°C. .

[0222] Figure 19 shows the external quantum efficiency-luminance characteristics of the light-emitting element 1. Brightness of 1-1: 1000 cd / m² 2 Table 2 shows the main characteristics of the vicinity.

[0223] [Table 2]

[0224] Thus, the light-emitting element 1 is a light-emitting element that exhibits very good efficiency with an external quantum efficiency of 11%. This can be understood.

[0225] Light-emitting element 1-1 is an element in which a film thickness adjustment layer is further formed on the light-emitting element 1. Optical path of the light-emitting element By adjusting the length, the light directed towards the front is attenuated, thereby expressing the orientation state. The value of a has been made easier to determine. Note that the configuration and manufacturing method of light-emitting element 1 and light-emitting element 1-1 are also described. In this case, the only difference is the presence or absence of a film thickness adjustment layer, therefore, the orientation of the light-emitting material in the light-emitting layer It can be inferred that the condition is the same.

[0226] Using light-emitting element 1-1, the orientation state of the light-emitting material in the light-emitting layer was investigated. First, Figure As shown in 20, the substrate on which the light-emitting element 1-1 is provided is used as a detector (manufactured by Hamamatsu Photonics Ltd.) The multi-channel spectrometer PMA-12) is tilted from θ = 0 to 80 degrees, and measurements are taken in 1-degree increments. The EL emission spectrum was measured, and the angular dependence of the spectral shape of the EL emission was measured. In the measurement, a linear polarizer (Grande) is placed perpendicular to the substrate surface between the light-emitting element 1-1 and the detector. A polarizing prism is inserted to remove S-polarized light from the light emitted by the light-emitting element 1-1, and P-polarized light is removed. The spectrum was measured.

[0227] Figure 21 shows the EL emission spectrum from 440 nm to 956 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, cgDBCzPA and 1,6 were placed on a quartz substrate. mMemFLPAPrn and cgDBCzPA were used in a weight ratio of 1:0.03, with a film thickness of 50 nm. To achieve this, a film co-deposited by vacuum deposition was used. Calculations using setfos showed Next, we define the light-emitting region. Here, the interface between the hole transport layer and the light-emitting layer is used as the vertex. The state of the emission region where the recombination probability exhibits an exponential decay curve with respect to the cathode direction (expon Assuming a critical ( ), the film thickness at which the recombination probability decays to 1 / e is set to 10 nm. The light region was set to be expanded. This allows the emission spectrum for each parameter a to be calculated. The angle dependence of the area intensity of the light can be calculated. When light-emitting element 1-1 has a=0.16 It showed good agreement with the calculated value.

[0228] Furthermore, Figure 22 shows the 2D contours measuring the angular dependence of the EL emission spectrum of light-emitting element 1-1. Figure 23 shows the contour plot (measured). Figure 23 also shows the 2D contour plot obtained by calculation. These findings show good agreement, and this indicates that the emission element is similar to that of the experiment and the calculations. This suggests that the orientation of the light-emitting material in child 1 and light-emitting element 1-1 was accurately determined. .

[0229] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.16 can capture 1.26 times more light than a light-emitting element with random orientation. It can be seen that this is the output efficiency. In other words, the light-emitting element of the present invention is a randomly oriented element This would result in a luminous efficiency 1.26 times greater.

[0230] Furthermore, since the light-emitting element 1 and light-emitting element 1-1 have the same light-emitting layer material and film formation method, Therefore, it can be said that the light-emitting element 1, like light-emitting element 1-1, has an orientation of a = 0.16. Element 1 is a light-emitting element that exhibits a very good external quantum efficiency of 11%, and the value of a is 0.2 or less. It was found that by doing so, a light-emitting element with good luminescence efficiency can be obtained. Furthermore, transient EL measurements revealed that this element was also generating TTA (Time Tolerance Analysis). cgDBCzPA and 1,6mMemFLPAPrn were mixed in a weight ratio of 1:0.03, and the film thickness was c The quantum yield of a film co-deposited by vacuum deposition such that gDBCzPA is 50 nm is At 360 nm excitation light, the average value was 0.85. In other words, the light-emitting layer of this embodiment is If a is 0.2 or less, and the fluorescence quantum yield is 0.84 or more, then TTA was not occurring. Even so, the theoretical conditions for an external quantum efficiency of 7.5% or higher are met. In this example, in addition to this, the external quantum efficiency exceeds 10% thanks to the occurrence of TTA. We were able to obtain a light-emitting element with extremely good characteristics. [Examples]

[0231] In this embodiment, a light-emitting element (light-emitting element 2) according to one embodiment of the present invention with good efficiency is used. A light-emitting element for measurement (light-emitting element 2) having a light-emitting layer with the front brightness minimized. We will now explain in detail the results of creating (-1) and determining a.

[0232] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0233] [ka]

[0234] (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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0235] 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.

[0236] 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 was left for approximately 30 minutes. It was allowed to cool.

[0237] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and the other are used in a weight ratio of 4:2 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing at a 50 nm depth.

[0238] Next, on the hole injection layer 111, 4-phenyl-4'-(9, represented by the above structural formula (ii) -phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) film thickness 2 A hole transport layer 112 was formed by depositing the material to a thickness of 0 nm.

[0239] Next, the above structural formula (vii) represents 2-[3'-(dibenzothiophene-4-i [biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPD) Bq-II) and N-(1,1'-biphenyl-4-I) represented by the above structural formula (viii) (Lu)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole-3-yl) Phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) and the above structural formula (ix ) represented as bis{2-[5-methyl-6-(2-methylphenyl)-4-pyrimidinyl -κN3]phenyl-κC}(2,4-pentanedionato-κ 2 O,O') Iridium ( III) (abbreviation: [Ir(mpmppm)2(acac)]) and a weight ratio of 0.8:0. 2:0.05(=2mDBTBPDBq-II:PCBBiF:[Ir(mpmppm) A light-emitting layer 113 was formed by co-depositing at a 40 nm depth so that it would be 2(acac)). During the formation of the optical layer 113 (during deposition), the Q-MASS measured in the deposition chamber The total pressure is 2 x 10 -4 The partial pressure of carbon dioxide, detected as having a molecular weight of 44, fluctuates around Pa. is 1 x 10 -6 It remained around Pa. That is, the carbon dioxide relative to the total pressure during deposition The ratio of partial pressure was approximately 0.5%. Thus, the proportion of carbon dioxide relative to the total pressure during deposition... It is important that the pressure ratio is greater than 0.03%, specifically 0.1% or more. Furthermore, since Q-MASS only detects gases with molecular weights of 1 to 200, Q-MASS The total pressure of S is not exactly the same as the actual total pressure inside the chamber. However, if the molecular weight exceeds 200 Since the partial pressure of the gaseous components is negligibly small, the same result can be obtained using any total pressure. It can be obtained.

[0240] Subsequently, 2mDBTBPDBq-II was vapor-deposited onto the light-emitting layer 113 to a thickness of 25 nm. After application, bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (v), is applied to the membrane. An electron transport layer 114 was formed by depositing a material to a thickness of 10 nm.

[0241] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 2 of this embodiment was fabricated by forming the second electrode 102 by vapor deposition.

[0242] (Method for fabricating light-emitting element 2-1) After forming the electron injection layer 115 of the above-mentioned light-emitting element 2-1, the above-mentioned structural formula (vi) A 2nm layer of copper phthalocyanine (abbreviated as CuPc) is formed, and DBT3P-II and acid The weight ratio of molybdenum(VI) to molybdenum(VI) is 2:1 (=DBT3P-II: molybdenum oxide). A film thickness adjustment layer was formed by co-depositing at 85 nm.

[0243] The element structures of light-emitting element 2 and light-emitting element 2-1 are summarized in the table below.

[0244] [Table 3]

[0245] The light-emitting element 2 and light-emitting element 2-1 are placed in a glove box in 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, the light-emitting element 2 and the light-emitting element Measurements were taken to determine the initial characteristics of 2-1. The measurements were performed in an atmosphere maintained at 25°C. .

[0246] Figure 24 shows the external quantum efficiency-luminance characteristics of the light-emitting element 2. Brightness of 2-1: 1000 cd / m² 2 Table 4 shows the main characteristics of the vicinity.

[0247] [Table 4]

[0248] Thus, the light-emitting element 2 is a light-emitting element that exhibits very good efficiency with an external quantum efficiency of 30%. This can be seen. Here, the luminescent material used this time is [Ir(mpmppm)2(acac The emission quantum yield (Φ) of )] is known to be 0.84. Carrier balance (γ If the ratio (x) is 1 and the exciton generation rate (α) is 1, then the light extraction efficiency (χ) is 35.7%. This is calculated to be higher than the generally accepted theoretical value of 20% to 30% for light extraction efficiency. The value is extremely large.

[0249] Light-emitting element 2-1 is an element in which a film thickness adjustment layer is further formed on light-emitting element 2. Optical path of the light-emitting element By adjusting the length, the light directed towards the front is attenuated, thereby expressing the orientation state. The value of a has been made easier to determine. Note that the configuration and manufacturing method of light-emitting element 2 and light-emitting element 2-1 are also described. In this case, the only difference is the presence or absence of a film thickness adjustment layer, therefore, the orientation of the light-emitting material in the light-emitting layer It can be inferred that the condition is the same.

[0250] Using light-emitting element 2-1, the orientation state of the light-emitting material in the light-emitting layer was investigated. First, Figure As shown in 20, the substrate on which the light-emitting element 2-1 is provided is used as a detector (manufactured by Hamamatsu Photonics Ltd.) The multi-channel spectrometer PMA-12) is tilted from θ = 0 to 80 degrees, and measurements are taken in 1-degree increments. The EL emission spectrum was measured, and the angular dependence of the spectral shape of the EL emission was measured. In the measurement, a linear polarizer (Gran) is placed perpendicular to the substrate surface between the light-emitting element 2-1- and the detector. A Taylor polarizing prism is inserted to remove S-polarized light from the light emitted by the light-emitting element 2-1, thereby removing P-polarized light. The spectrum was measured for only that component.

[0251] Figure 25 shows the EL emission spectrum from 440 nm to 956 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, 2mDBTBPDBq-I was placed on a quartz substrate. I, PCBBiF, and Ir(mpmppm)2(acac) in a weight ratio of 0.8:0.2:0 A film was used that was co-deposited by vacuum deposition to a thickness of 0.05 nm. In the calculation using etfos, the luminescence region is further defined. Here, the hole transport layer and With the interface of the light-emitting layer as the peak, the recombination probability exhibits an exponential decay curve with respect to the cathode direction. Assuming an exponential state in the luminescent region, the recombination probability of the film decays to 1 / e. The setting was made so that the light-emitting region expands to a thickness of 25 nm. This allows the parameters For each 'a', the angular dependence of the area intensity of its emission spectrum can be calculated. Child 2-1 showed good agreement with the graph for a=0.18.

[0252] Furthermore, Figure 26 shows the 2D contour plots measuring the angle dependence of the EL emission spectrum of light-emitting element 2-1. Figure 27 shows the contour plot (measured by actual measurement). Figure 27 also shows the 2D contour plot obtained by calculation. Furthermore, these show good agreement, and this is because the luminescence in this experiment and the calculations are similar. This suggests that the orientation of the light-emitting material in element 2 and light-emitting element 2-1 was accurately determined. ru.

[0253] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.18 can capture 1.23 times more light than a light-emitting element with random orientation. It can be seen that this is related to output efficiency.

[0254] Furthermore, since the light-emitting element 2 and light-emitting element 2-1 use the same material for their light-emitting layer and the same film formation method, Therefore, it can be said that light-emitting element 2, like light-emitting element 2-1, has an orientation of a = 0.18. Element 2 is a light-emitting element that exhibits a very good external quantum efficiency of 30%, and the value of a is 0.2 or less. It was found that by doing so, a light-emitting element with good luminescence efficiency can be obtained. Also, 2mDBTBPDBq-II and PCBBiF and Ir(mpmppm)2(acac ) are combined by vacuum deposition in a weight ratio of 0.8:0.2:0.05, with a film thickness of 50 nm. The quantum yield of the co-evaporated film was 0.84 on average under excitation light at 370 nm. In other words, the light-emitting layer of this embodiment has a value of 0.2 or less and a phosphorescence quantum yield of 0.84 or more. Furthermore, it satisfies the theoretical conditions under which the external quantum efficiency can be 30% or higher. [Examples]

[0255] In this embodiment, a light-emitting element (light-emitting element 3) according to one embodiment of the present invention with good efficiency is used. A light-emitting element for measurement (light-emitting element 3) having a light-emitting layer with a configuration that minimizes front brightness. We will now explain in detail the results of creating (-1) and determining a.

[0256] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0257] [ka]

[0258] (Method for fabricating the light-emitting element 3) 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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0259] 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.

[0260] 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 was left for approximately 30 minutes. It was allowed to cool.

[0261] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and DBT3P-II are used in a weight ratio of 2:1 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing at 75 nm.

[0262] Next, on the hole injection layer 111, 4-phenyl-4'-(9, represented by the above structural formula (ii) -phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) film thickness 2 A hole transport layer 112 was formed by depositing the material to a thickness of 0 nm.

[0263] Next, the above structural formula (vii) represents 2-[3'-(dibenzothiophene-4-i [biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPD) Bq-II) and N-(1,1'-biphenyl-4-I) represented by the above structural formula (viii) (Lu)-9,9-dimethyl-N-[4-(9-phenyl-9H-carbazole-3-yl) Phenyl]-9H-fluoren-2-amine (abbreviation: PCBBiF) and the above structural formula (x) Represented as bis{2-[5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl) [Phenyl)-2-pyrazinyl-κN]-4,6-dimethylphenyl-κC}(2,2,6, 6-tetramethyl-3,5-heptanedionato-κ 2 O,O') Iridium(III) Abbreviation: [Ir(dmdppr-dmp)2(dpm)]) and weight ratio 0.8:0.2: 0.05(=2mDBTBPDBq-II:PCBBiF:[Ir(dmdppr-dm A light-emitting layer 113 was formed by co-depositing at a density of 40 nm such that the value was p)2(dpm).

[0264] Subsequently, 2mDBTBPDBq-II was vapor-deposited onto the light-emitting layer 113 to a thickness of 30 nm. After application, bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (v), is applied to the membrane. An electron transport layer 114 was formed by depositing a material to a thickness of 15 nm.

[0265] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 3 of this embodiment was fabricated by forming the second electrode 102 by vapor deposition.

[0266] (Method for fabricating light-emitting element 3-1) After the electron injection layer 115 of the above-mentioned light-emitting element 3-1 is formed, the above-mentioned structural formula (vi) A 2nm layer of copper phthalocyanine (abbreviated as CuPc) is formed, and DBT3P-II and acid The weight ratio of molybdenum(VI) to molybdenum(VI) is 2:1 (=DBT3P-II: molybdenum oxide). A 100nm co-deposited layer was used to form a film thickness adjustment layer.

[0267] The element structures of light-emitting element 3 and light-emitting element 3-1 are summarized in the table below.

[0268] [Table 5]

[0269] The light-emitting element 3 and light-emitting element 3-1 are placed in a glove box in 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, the light-emitting element 3 and the light-emitting element are subjected to UV treatment and heat treatment at 80°C for 1 hour. Measurements were taken to determine the initial characteristics of 3-1. The measurements were performed in an atmosphere maintained at 25°C. .

[0270] Figure 28 shows the external quantum efficiency-luminance characteristics of the light-emitting element 3. Brightness of 3-1: 1000 cd / m² 2 Table 6 shows the main characteristics of the vicinity.

[0271] [Table 6]

[0272] Thus, the light-emitting element 3 is a light-emitting element that exhibits very good efficiency with an external quantum efficiency of 27%. This can be seen. Here, the luminescent material used this time is [Ir(dmdppr-dmp)2( The emission quantum yield (Φ) of dpm is known to be 0.79. Carrier balance If the γ is 1 and the exciton generation rate (α) is 1, then the light extraction efficiency (χ) is 34 This is calculated to be 0.1%. This is compared to the generally accepted theoretical value of 20% to 30% for light extraction efficiency. This value is significantly larger than that.

[0273] The light-emitting element 3-1 is an element having a configuration that further includes a film thickness adjustment layer in addition to the configuration of the light-emitting element 3. By adjusting the optical path length of the light-emitting element, the light directed forward is attenuated. Furthermore, the value of 'a' representing the orientation state was made easier to determine. Note that light-emitting element 3 and light-emitting element 3-1 are Since the only difference in the structure and manufacturing method is the presence or absence of a film thickness adjustment layer, in the light-emitting layer It can be inferred that the orientation of the luminescent material is the same.

[0274] The orientation state of the light-emitting material in the light-emitting layer was investigated using light-emitting element 3-1. The details are the same as in Example 1 or Example 2, so they are omitted.

[0275] Figure 29 shows the EL emission spectrum from 570 nm to 900 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, 2mDBTBPDBq-I was placed on a quartz substrate. I, PCBBiF, and [Ir(dmdppr-dmp)2(dpm)] in a weight ratio of 0.8: A film was co-deposited by vacuum deposition with a ratio of 0.2:0.05 and a film thickness of 50 nm. It was used. In the calculation using setfos, the emission region is further set. Here, Ho The recombination probability follows a Gaussian function distribution, with a peak around 38 nm from the interface between the transport layer and the light-emitting layer. Assuming a state (Gaussian) in the emission region that exhibits a corresponding decay curve, the assumed Gaussian function The emission region was set to expand so that the distance between the inflection points of the number is 28 nm. Furthermore, for each parameter a, the angular dependence of the area intensity of its emission spectrum can be calculated. Yes, it is possible. Light-emitting element 3-1 showed good agreement with the graph for a=0.16.

[0276] Furthermore, Figure 30 shows the 2D contours measuring the angle dependence of the EL emission spectrum of the light-emitting element 3-1. Figure 31 shows the contour plot (measured by actual measurement). Figure 31 also shows the 2D contour plot obtained by calculation. Furthermore, these show good agreement, and this is because the luminescence in this experiment and the calculations are similar. This suggests that the orientation of the light-emitting material in element 3 and light-emitting element 3-1 was accurately determined. ru.

[0277] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.16 can capture 1.26 times more light than a light-emitting element with random orientation. It can be seen that this is related to output efficiency.

[0278] Furthermore, since the light-emitting element 3 and light-emitting element 3-1 use the same material for their light-emitting layer and the same film formation method, In the light-emitting layer of the light-emitting element 3, [Ir(dmdppr-dmp)2(dpm)] is emitted. Similar to optical element 3-1, it can be said that it has an orientation of a=0.16. The light-emitting element 3 is externally quantum. This light-emitting element exhibits a very good value of 27%, and the value of a is 0.2 or less, which indicates good performance. It was found that a light-emitting element with good luminescence efficiency can be obtained. [Examples]

[0279] In this embodiment, a light-emitting element (light-emitting element 4) according to one embodiment of the present invention with good efficiency is used. A light-emitting element (light-emitting element 4) for measurement, having a light-emitting layer with the configuration such that the front brightness is minimized. We will now explain in detail the results of creating (-1) and determining a.

[0280] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0281] [ka]

[0282] (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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0283] 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.

[0284] 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 was left for approximately 30 minutes. It was allowed to cool.

[0285] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and DBT3P-II are used in a weight ratio of 2:1 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing a 20 nm layer in this manner.

[0286] Next, on the hole injection layer 111, 3,3'-bis(9-fe) represented by the above structural formula (xi) is injected. Nyl-9H-carbazole (abbreviated as PCCP) was deposited to a film thickness of 20 nm, and A pore transport layer 112 was formed.

[0287] Next, we have PCCP and 4,6-bis[3-(9H-cal] represented by the above structural formula (xii). [Bazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) and the above structure Tris {2-[4-(4-cyano-2,6-diisobutylphenate}, represented by formula (xiii) (Nyl)-5-(2-methylphenyl)-4H-1,2,4-triazole-3-yl-κ N 2 ]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-diBuC Np)3]) and the weight ratio is 0.6:0.4:0.125 (=PCCP:4,6mCzP2 After co-depositing 30 nm so that Pm:[Ir(mpptz-diBuCNp)3]) , weight ratio 0.2:0.8:0.125(=PCCP:4,6mCzP2Pm:[Ir(m A luminescent layer 113 is formed by co-depositing 10 nm of material so that it is pptz-diBuCNp)3]). did.

[0288] Subsequently, 4,6mCzP2Pm was deposited onto the light-emitting layer 113 to a thickness of 10 nm. Next, bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (v), is applied to a film thickness of 15 An electron transport layer 114 was formed by depositing material to an nm size.

[0289] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 4 of this embodiment was fabricated by forming the second electrode 102 by vapor deposition.

[0290] (Method for fabricating light-emitting element 4-1) After the electron injection layer 115 of the above-mentioned light-emitting element 4-1 is formed, the above-mentioned structural formula (vi) A 2nm layer of copper phthalocyanine (abbreviated as CuPc) is formed, and DBT3P-II and acid The weight ratio of molybdenum(VI) to molybdenum(VI) is 2:1 (=DBT3P-II: molybdenum oxide). A 55nm co-deposited layer was used to form a film thickness adjustment layer.

[0291] The element structures of light-emitting element 4 and light-emitting element 4-1 are summarized in the table below.

[0292] [Table 7]

[0293] The light-emitting element 4 and light-emitting element 4-1 are 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, the light-emitting element 4 and the light-emitting element are subjected to UV treatment and heat treatment at 80°C for 1 hour. Measurements were taken to determine the initial characteristics of 4-1. The measurements were performed in an atmosphere maintained at 25°C. .

[0294] Figure 32 shows the external quantum efficiency-luminance characteristics of the light-emitting element 4. Brightness of 4-1: 1000 cd / m² 2 Table 8 shows the main characteristics of the vicinity.

[0295] [Table 8]

[0296] Thus, the light-emitting element 4 is a light-emitting element that exhibits very good efficiency with an external quantum efficiency of 30%. This can be seen. Here, the luminescent material used this time is [Ir(mpptz-diBuCNp The emission quantum yield (Φ) of )3] is known to be 0.93. Carrier balance ( If γ is 1 and the exciton generation rate (α) is 1, then the light extraction efficiency (χ) is 32.3 This is calculated as a percentage. This is higher than the generally accepted theoretical value of 20% to 30% for light extraction efficiency. This is also a very large value.

[0297] The light-emitting element 4-1 is an element having a configuration that further includes a film thickness adjustment layer in addition to the configuration of the light-emitting element 4. By adjusting the optical path length of the light-emitting element, the light directed forward is attenuated. Furthermore, the value of 'a' representing the orientation state was made easier to determine. Note that light-emitting element 4 and light-emitting element 4-1 are Since the only difference in the structure and manufacturing method is the presence or absence of a film thickness adjustment layer, in the light-emitting layer It can be inferred that the orientation of the luminescent material is the same.

[0298] The orientation state of the light-emitting material in the light-emitting layer was investigated using light-emitting element 4-1. The details are the same as in Example 1 or Example 2, so they are omitted.

[0299] Figure 33 shows the EL emission spectrum from 350 nm to 810 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurements, PCCP and 4,6 mCzP were placed on a quartz substrate. 2Pm and [Ir(mpptz-diBuCNp)3] in a weight ratio of 0.6:0.4:0.1 A film with a 15nm co-deposited layer was used to achieve a value of 25. Calculations using setfos showed that... Next, the light-emitting region is defined. The peak is set approximately 20 nm from the interface between the hole transport layer and the light-emitting layer. , the state of the emission region where the recombination probability exhibits a decay curve following a Gaussian function distribution (gaussia Assuming n), the emission region expands such that the distance between the inflection points of the assumed Gaussian function is 30 nm. This was set to be the case. As a result, for each parameter a, the area intensity of its emission spectrum The angle dependence in degrees can be calculated. The graph for light-emitting element 4-1 is good when a=0.15. They showed agreement.

[0300] Furthermore, Figure 34 shows the 2D contours measuring the angular dependence of the EL emission spectrum of light-emitting element 4-1. Figure 35 shows the contour plot (measured by actual measurement). Figure 35 also shows the 2D contour plot obtained by calculation. Furthermore, these show good agreement, and this is because the luminescence in this experiment and the calculations are similar. This suggests that the orientation of the light-emitting material in element 4 and light-emitting element 4-1 was accurately determined. ru.

[0301] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.15 can capture 1.28 times more light than a light-emitting element with random orientation. It can be seen that this is related to output efficiency.

[0302] Furthermore, since the light-emitting element 4 and light-emitting element 4-1 have the same light-emitting layer material and film deposition method, In the light-emitting layer of the light-emitting element 4, [Ir(mpptz-diBuCNp)3] is a light-emitting element Similar to child 4-1, it can be said that it has an orientation of a=0.15. The light-emitting element 4 has an external quantum efficiency of 3 This light-emitting element shows a very good value of 0%, and the value of a is 0.2 or less, indicating good performance. It was found that a light-emitting element with high luminous efficiency can be obtained.

[0303] Also, PCCP, 4,6mCzP2Pm, and [Ir(mpptz-diBuCNp)3] The quantum yield of a film co-deposited at 50 nm with a weight ratio of 0.6:0.4:0.125 is: At excitation light of 350 nm, the average was 80%. That is, the light-emitting layer in this embodiment is a The value is 0.2 or less, the phosphorescent quantum yield is 80% or more, and the external quantum efficiency is 30% or more. The theoretical conditions for obtaining it are met. [Examples]

[0304] In this embodiment, a light-emitting element (light-emitting element 5) according to one embodiment of the present invention with good efficiency is used. A light-emitting element for measurement (light-emitting element 5) having a light-emitting layer with a configuration that minimizes front brightness. We will now explain in detail the results of creating (-1) and determining a.

[0305] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0306] [ka]

[0307] (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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0308] 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.

[0309] 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 was left for approximately 30 minutes. It was allowed to cool.

[0310] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and DBT3P-II are used in a weight ratio of 2:1 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing a 20 nm layer in this manner.

[0311] Next, on the hole injection layer 111, 4,4'-bis(9- Carbazole-2,2'-dimethyl-biphenyl (abbreviation: dmCBP) film thickness 20 nm The hole transport layer 112 was formed by depositing the material in such a manner.

[0312] Next, 3,5-bis[3-(9H-carbazole-9], represented by the above structural formula (xv), is shown. -yl)phenyl]pyridine (abbreviation: 35DCzPPy) and the above structural formula (xvi) Tris{2-[4-(2-adamantyl)-3-methyl-4H-1,2,4-tri Azole-5-yl-κN]phenyl-κC}iridium(III) (abbreviation: [Ir(M ptz-Adm2)3]) and the weight ratio 1:0.06 (=35DCzPPy:[Ir(M A light-emitting layer 113 was formed by co-depositing 30 nm of material in the form of ptz-Adm2)3).

[0313] Subsequently, on the light-emitting layer 113, 1,3,5-tris[3] represented by the above structural formula (xvii) is applied. -(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB) was deposited at a 25 nm depth, and electron A transport layer 114 was formed.

[0314] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 5 of this embodiment was fabricated by forming a second electrode 102 by vapor deposition.

[0315] (Method for fabricating the light-emitting element 5-1) After the electron injection layer 115 of the above-mentioned light-emitting element 5-1 is formed, the above-mentioned structural formula (vi) A 2nm layer of copper phthalocyanine (abbreviated as CuPc) is formed, and DBT3P-II and acid The weight ratio of molybdenum(VI) to molybdenum(VI) is 2:1 (=DBT3P-II: molybdenum oxide). A 60nm co-deposited layer was used to form a film thickness adjustment layer.

[0316] The element structures of light-emitting element 5 and light-emitting element 5-1 are summarized in the table below.

[0317] [Table 9]

[0318] The light-emitting element 5 and light-emitting element 5-1 are 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, the light-emitting element 5 and the light-emitting element Measurements were taken to determine the initial characteristics of 5-1. The measurements were performed in an atmosphere maintained at 25°C. .

[0319] Figure 36 shows the external quantum efficiency-luminance characteristics of the light-emitting element 5. Brightness of 5-1: 1000 cd / m² 2 Table 10 shows the main characteristics of the vicinity.

[0320] [Table 10]

[0321] Thus, the light-emitting element 5 is a light-emitting element that exhibits good efficiency with an external quantum efficiency of 25%. I understand. Here, the amount of light emitted by the light-emitting material [Ir(Mptz-Adm2)3] used this time... The yield (Φ) is known to be 0.94. The carrier balance (γ) is 1, excitation If the seed generation rate (α) is 1, the light extraction efficiency (χ) is calculated to be 26.6%. .

[0322] The light-emitting element 5-1 is an element having a configuration that further includes a film thickness adjustment layer in addition to the configuration of the light-emitting element 5. By adjusting the optical path length of the light-emitting element, the light directed forward is attenuated. Furthermore, the value of 'a', which represents the orientation state, was made easier to determine. Note that light-emitting element 5 and light-emitting element 5-1 are Since the only difference in the structure and manufacturing method is the presence or absence of a film thickness adjustment layer, in the light-emitting layer It can be inferred that the orientation of the luminescent material is the same.

[0323] Using the light-emitting element 5-1, we investigated the orientation state of the light-emitting material in the light-emitting layer. First, Figure As shown in 20, the substrate on which the light-emitting element 5-1 is provided is used as a detector (manufactured by Hamamatsu Photonics Ltd.) The multi-channel spectrometer PMA-12) is tilted from θ = 0 to 80 degrees for 10 degrees. The EL emission spectrum was measured for each instance, and the angular dependence of the spectral shape of the EL emission was measured. In this measurement, a linear polarizer (Gran) is placed perpendicular to the substrate surface between the light-emitting element 5-1 and the detector. A Taylor polarizing prism is inserted to remove S-polarized light from the light emitted by the light-emitting element 5-1, and P-polarized light is removed. The spectrum was measured for only that component.

[0324] Figure 37 shows the EL emission spectrum from 400 nm to 800 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, 35DCzPPy and [Ir (Mptz-Adm2)3) is used in a vacuum with a weight ratio of 1:0.06 and a film thickness of 50 nm. A film co-deposited by vapor deposition was used. Calculations using setfos further showed that luminescence... The region is defined. Here, the interface between the hole transport layer and the light emission layer is used as the vertex, and the recombination probability is The state of the emission region exhibiting an exponential decay curve with respect to the cathode direction. Assuming that the recombination probability decreases to 1 / e, the luminescent region expands so that the film thickness at which the recombination probability decreases to 5 nm is 5 nm. This was set to: For each parameter a, the area intensity of its emission spectrum The angle dependence can be calculated. The graph for light-emitting element 5-1 shows good agreement with the graph for a=0.16. This was shown.

[0325] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.16 can capture 1.26 times more light than a light-emitting element with random orientation. It can be seen that this is related to output efficiency.

[0326] Furthermore, since the light-emitting element 5 and light-emitting element 5-1 have the same light-emitting layer material and film formation method, In the light-emitting layer of the light-emitting element 5, [Ir(Mptz-Adm2)3] is present in light-emitting element 5-1 Similarly, it can be said that it has an orientation of a=0.16. The light-emitting element 5 has a good external quantum efficiency of 25%. This light-emitting element exhibits favorable values, and having a value of 'a' of 0.2 or less indicates good luminous efficiency. It was found that a light-emitting element can be obtained. [Examples]

[0327] In this embodiment, a light-emitting element (light-emitting element 6) according to one embodiment of the present invention with good efficiency is used. A light-emitting element (light-emitting element 6) for measurement, having a light-emitting layer with the configuration designed to minimize front brightness. We will explain in detail the results of fabricating (-1) and determining a. Figure 18 shows the element structure of the light-emitting device. This will be shown.

[0328] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0329] [ka]

[0330] (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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0331] 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.

[0332] 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 was left for approximately 30 minutes. It was allowed to cool.

[0333] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and the other are used in a weight ratio of 4:2 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing at a 40 nm depth.

[0334] Next, on the hole injection layer 111, 4-phenyl-4'-(9, represented by the above structural formula (ii) -phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP) film thickness 3 A hole transport layer 112 was formed by depositing the material to a thickness of 0 nm.

[0335] Next, the 7-[4-(10-phenyl-9-antriol] represented by the above structural formula (iii) is shown. [Phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA) The above structural formula (xviii) represents N,N'-bis(3-methylphenyl)-N,N' -Bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]-anthracene -9,10-diamine (abbreviation: 9,10mMemFLPA2A) and -9,10-diamine in a weight ratio of 1:0.1 Co-deposited at 35 nm so that (=cgDBCzPA:9,10mMemFLPA2A) A light-emitting layer 113 was formed.

[0336] Subsequently, bathophenanthroline represented by the above structural formula (v) (abbreviation: BPhen) was deposited to a thickness of 15 nm to form an electron transport layer 114.

[0337] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 6 of this embodiment was fabricated by forming the second electrode 102 by vapor deposition.

[0338] (Method for fabricating the light-emitting element 6-1) After forming the electron injection layer 115 of the above-mentioned light-emitting element 6-1, the above-mentioned structural formula (vi) Copper phthalocyanine (abbreviated as CuPc), represented by [formula], is deposited to a thickness of 2 nm and then electron relay is performed. - A layer 118 is formed, and DBT3P-II and molybdenum(VI) oxide are mixed in a weight ratio of 2:1 (= A P-type layer 117 is formed by co-depositing 80 nm of DBT3P-II (molybdenum oxide) to create a P-type layer 117. This was done, and a film thickness adjustment layer was formed.

[0339] The element structures of light-emitting element 6 and light-emitting element 6-1 are summarized in the table below.

[0340] [Table 11]

[0341] The light-emitting element 6 and light-emitting element 6-1 are placed in a glove box in 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, the light-emitting element 6 and the light-emitting element The initial characteristics of 6-1 were measured. The measurements were taken in an atmosphere maintained at 25°C. .

[0342] Figure 38 shows the external quantum efficiency-luminance characteristics of the light-emitting element 6. Brightness of 6-1: 1000 cd / m² 2 Table 12 shows the main characteristics of the vicinity.

[0343] [Table 12]

[0344] Thus, the light-emitting element 6 is a light-emitting element that exhibits good efficiency with an external quantum efficiency of 8.3%. This shows the emission quantum of 9,10mMemFLPA2A, the light-emitting material used in this study. The yield (Φ) is known to be 0.90. The carrier balance (γ) is 1, exciton Assuming a generation rate (α) of 0.25, the light extraction efficiency (χ) is calculated to be 36.9%. This is significantly higher than the generally accepted theoretical value of 20% to 30% for light extraction efficiency. It is a key value.

[0345] The light-emitting element 6-1 is an element in which a film thickness adjustment layer is further formed on the light-emitting element 6. By adjusting the length, the light directed towards the front is attenuated, thereby expressing the orientation state. The value of a has been made easier to determine. Note that the configuration and manufacturing method of light-emitting element 6 and light-emitting element 6-1 are also described. In this case, the only difference is the presence or absence of a film thickness adjustment layer, therefore, the orientation of the light-emitting material in the light-emitting layer It can be inferred that the condition is the same.

[0346] Using the light-emitting element 6-1, we investigated the orientation state of the light-emitting material in the light-emitting layer. First, Figure As shown in 20, the substrate on which the light-emitting element 6-1 is provided is used as a detector (manufactured by Hamamatsu Photonics Ltd.) The multi-channel spectrometer PMA-12) is tilted from θ = 0 to 80 degrees, and measurements are taken in 1-degree increments. The EL emission spectrum was measured, and the angular dependence of the spectral shape of the EL emission was measured. In the measurement, a linear polarizer (Grande) is placed perpendicular to the substrate surface between the light-emitting element 6-1 and the detector. A polarizing prism is inserted to remove S-polarized light from the light emitted by the light-emitting element 6-1, and P-polarized light is removed. The spectrum was measured.

[0347] Figure 39 shows the EL emission spectrum from 470 nm to 750 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, cgDBCzPA and 9,1 were placed on a quartz substrate. Vacuum deposition method using 0mMemFLPA2A in a weight ratio of 1:0.1, with a film thickness of 50nm. A film co-deposited using the following method was used. In the calculation using setfos, the setting of the light-emitting region was further determined. The determination is made. Here, the peak is around 33 nm from the interface between the hole transport layer and the light-emitting layer, and the recombination Let's assume a state (Gaussian) in the luminescence region where the probability follows a Gaussian function distribution and exhibits a decay curve. The luminescent region expands so that the distance between the inflection points of the assumed Gaussian function is 12.5 nm. This was set to: For each parameter a, the area intensity of its emission spectrum The angle dependence can be calculated. For light-emitting element 6-1, the graph is good when a=0.19. They showed agreement.

[0348] Furthermore, Figure 40 shows the 2D contours of the EL emission spectrum of light-emitting element 6-1, measured for angle dependence. Figure 41 shows the contour plot (measured). Figure 41 also shows the 2D contour plot obtained by calculation. These findings show good agreement, and this indicates that the emission element is similar to that of the experiment and the calculations. This suggests that the orientation of the light-emitting material in child 6 and light-emitting element 6-1 was accurately determined. .

[0349] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.19 has 1.22 times the light absorption capacity of a light-emitting element with random orientation. It can be seen that this is the output efficiency. In other words, the light-emitting element of the present invention is a randomly oriented element This would result in a luminous efficiency 1.22 times greater.

[0350] Furthermore, since the light-emitting element 6 and light-emitting element 6-1 use the same material for their light-emitting layer and the same film formation method, Therefore, it can be said that the light-emitting element 6, like the light-emitting element 6-1, has an orientation of a = 0.19. Element 6 is a light-emitting element that exhibits a very good external quantum efficiency of 8.3%, and the value of a is 0.2 It was found that by meeting the following conditions, a light-emitting element with good luminescence efficiency can be obtained. . [Examples]

[0351] In this embodiment, a light-emitting element (light-emitting element 7) according to one embodiment of the present invention with good efficiency is used. A light-emitting element (light-emitting element 7) for measurement, having a light-emitting layer with a configuration that minimizes front brightness. We will explain in detail the results of fabricating (-1) and determining a. Figure 18 shows the element structure of the light-emitting device. This will be shown.

[0352] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0353] [ka]

[0354] (Method for fabricating the light-emitting element 7) 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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0355] 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.

[0356] 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 was left for approximately 30 minutes. It was allowed to cool.

[0357] 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 a vapor deposition method using resistance heating, 2, 3, 6, 7, 10, represented by the above structural formula (xix) are obtained. 11-Hexacyano-1,4,5,8,9,12-Hexazatriphenylene (abbreviation: H A hole injection layer 111 was formed by depositing AT-CN at a 10 nm layer.

[0358] Next, on the hole injection layer 111, 4,4'-bis[N-(1 -Naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) to a film thickness of 80 nm The hole transport layer 112 was formed by depositing the material in this manner.

[0359] Next, rubrene represented by the above structural formula (xxi) and the above structural formula (xxii) 9-(1-naphthyl)-10-(2-naphthyl)anthracene (abbreviation: α,β-AD) N) and 5,10,15,20-tetraphenylbi represented by the above structural formula (xxiii). Sbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene( (Abbreviation: DBP) and a weight ratio of 0.8:0.2:0.005 (=Lubren:α,β-ADN A light-emitting layer 113 was formed by co-depositing at a density of 30 nm to achieve the following properties (DBP):

[0360] Subsequently, bathophenanthroline represented by the above structural formula (v) (abbreviation: BPhen) was deposited to a thickness of 20 nm to form an electron transport layer 114.

[0361] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 7 of this embodiment was fabricated by forming the second electrode 102 by vapor deposition.

[0362] (Method for fabricating the light-emitting element 7-1) After forming the electron injection layer 115 of the above-mentioned light-emitting element 7-1, the above-mentioned structural formula (vi) Copper phthalocyanine (abbreviated as CuPc), represented by [formula], is deposited to a thickness of 2 nm and then electron relay is performed. - A layer 118 is formed, and DBT3P-II and molybdenum(VI) oxide are mixed in a weight ratio of 2:1 (= A P-type layer 117 is formed by co-depositing at 85 nm to create DBT3P-II (molybdenum oxide). This was done, and a film thickness adjustment layer was formed.

[0363] The element structures of light-emitting element 7 and light-emitting element 7-1 are summarized in the table below.

[0364] [Table 13]

[0365] The light-emitting element 7 and light-emitting element 7-1 are placed in a glove box in 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, the light-emitting element 7 and the light-emitting element The initial characteristics of 7-1 were measured. The measurements were taken in an atmosphere maintained at 25°C. .

[0366] Figure 42 shows the external quantum efficiency-luminance characteristics of the light-emitting element 7. Brightness of 7-1: 1000 cd / m² 2Table 14 shows the main characteristics of the vicinity.

[0367] [Table 14]

[0368] Thus, the light-emitting element 7 is a light-emitting element that exhibits very good efficiency with an external quantum efficiency of 11%. This can be seen. Here, the emission quantum yield (Φ) of DBP, the light-emitting material used in this study, is 0.7 It is known to be 2. The carrier balance (γ) is 1, and the exciton generation rate (α) is 0. If it is 0.25, the light extraction efficiency (χ) is calculated to be 61.1%. This is generally This value is significantly higher than the theoretical value of 20% to 30% for light extraction efficiency. Furthermore, it has been found that TTA also occurs in this element from transient EL measurements, and in fact In TTA, the exciton generation rate is greater than 0.25.

[0369] The light-emitting element 7-1 is an element in which a film thickness adjustment layer is further formed on the light-emitting element 7. By adjusting the length, the light directed towards the front is attenuated, thereby expressing the orientation state. The value of a has been made easier to determine. Note that the configuration and manufacturing method of light-emitting element 7 and light-emitting element 7-1 are also described. In this case, the only difference is the presence or absence of a film thickness adjustment layer, therefore, the orientation of the light-emitting material in the light-emitting layer It can be inferred that the condition is the same.

[0370] Using the light-emitting element 7-1, we investigated the orientation state of the light-emitting material in the light-emitting layer. First, Figure As shown in 20, the substrate on which the light-emitting element 7-1 is provided is used as a detector (manufactured by Hamamatsu Photonics Ltd.) The multi-channel spectrometer PMA-12) is tilted from θ = 0 to 80 degrees, and measurements are taken in 1-degree increments. The EL emission spectrum was measured, and the angular dependence of the spectral shape of the EL emission was measured. In the measurement, a linear polarizer (Grande) is placed perpendicular to the substrate surface between the light-emitting element 7-1 and the detector. A polarizing prism is inserted to remove S-polarized light from the light emitted by the light-emitting element 7-1, and P-polarized light is removed. The spectrum was measured.

[0371] Figure 43 shows the EL emission spectrum from 570 nm to 900 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, rubrene and α,β-ADN were placed on a quartz substrate. Vacuum deposition was performed using DBP in a weight ratio of 0.8:0.2:0.005, with a film thickness of 50 nm. A film co-deposited by the method was used. Calculations using setfos further showed the emission region. The settings are configured. Here, the peak is set to approximately 6 nm from the interface between the hole transport layer and the light-emitting layer. The state of the luminescence region (Gaussian) where the probability of success follows a Gaussian function distribution of decay curves is Assuming that the distance between the inflection points of the assumed Gaussian function is 25 nm, the luminescent region expands. This was set to be present. This allows for the angle of the area intensity of the emission spectrum for each parameter a. The degree dependence can be calculated. For the light-emitting element 7-1, the graph is good when a=0.12. They showed agreement.

[0372] Furthermore, Figure 44 shows the 2D contours measuring the angular dependence of the EL emission spectrum of the light-emitting element 7-1. Figure 45 shows the contour plot (measured). Figure 45 also shows the 2D contour plot obtained by calculation. These findings show good agreement, and this indicates that the emission element is similar to that of the experiment and the calculations. This suggests that the orientation of the light-emitting material in child 7 and light-emitting element 7-1 was accurately determined. .

[0373] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.12 can capture 1.32 times more light than a light-emitting element with random orientation. It can be seen that this is the output efficiency. In other words, the light-emitting element of the present invention is a randomly oriented element This would result in a luminous efficiency 1.32 times higher.

[0374] Furthermore, since the light-emitting element 7 and light-emitting element 7-1 have the same light-emitting layer material and film deposition method, Therefore, the light-emitting element 7, like the light-emitting element 7-1, can be said to have an orientation of a = 0.12. Element 7 is a light-emitting element that exhibits a very good external quantum efficiency of 11%, and the value of a is 0.2 or less. It was found that by doing so, a light-emitting element with good luminescence efficiency can be obtained. Furthermore, transient EL measurements revealed that this element was generating TTA (Time Tolerance). [Examples]

[0375] In this embodiment, a light-emitting element (light-emitting element 8) according to one embodiment of the present invention with good efficiency is used. A light-emitting element for measurement (light-emitting element 8) having a light-emitting layer structure, with the front brightness minimized. We will now explain in detail the results of creating (-1) and determining a.

[0376] First, a method for manufacturing a light-emitting element according to one aspect of the present invention and its structure will be described. The organic compounds used in the light-emitting element of the embodiment are shown below.

[0377] [ka]

[0378] (Method for fabricating the light-emitting element 8) 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 70 nm, and the electrode surface The product was set to 2mm x 2mm.

[0379] 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.

[0380] 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 was left for approximately 30 minutes. It was allowed to cool.

[0381] 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 a vapor deposition method using resistance heating, 4,4',4''-(benzene) represented by the above structural formula (i) is obtained. (n-1,3,5-triyl)tri(dibenzothiophene) (abbreviation: DBT3P-II) Molybdenum(VI) oxide and the other are used in a weight ratio of 4:2 (=DBT3P-II:molybdenum oxide). A hole injection layer 111 was formed by co-depositing at a 50 nm depth.

[0382] Next, on the hole injection layer 111, 9-[3-(9-Fe, represented by the above structural formula (xxiv)) is injected. Nyl-9H-fluoren-9-yl)phenyl]-9H-carbazole (abbreviation: mCzF) A hole transport layer 112 was formed by depositing LP to a thickness of 20 nm.

[0383] Next, the 4,6-bis[3-(9H-carbazole- represented by the above structural formula (xii) 9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm) and the above structural formula (xx bis[2-(6-tert-butyl-4-pyrimidinyl-κN) represented as v) 3 ) Phoenix [2,4-pentanedionato-κC](2,4-pentanedionato-κ 2 O,O') Iridium(III) (Abbreviation: [Ir(tBuppm)2(acac)]) and a weight ratio of 1:0.05 (=4,6mCz) Co-deposit 40nm so that P2Pm:[Ir(tBuppm)2(acac)]) A light-emitting layer 113 was formed.

[0384] Subsequently, 4,6mCzP2Pm was deposited onto the light-emitting layer 113 to a thickness of 15nm. Next, bathophenanthroline (abbreviated as BPhen), represented by the above structural formula (v), is applied to a film thickness of 10 An electron transport layer 114 was formed by depositing material to an nm size.

[0385] After forming the electron transport layer 114, lithium oxide (Li2O) is applied to a thickness of 0.1 nm. A layer 115 is formed by depositing an electron injection layer, followed by aluminum to a thickness of 200 nm. The light-emitting element 8 of this embodiment was fabricated by forming the second electrode 102 by vapor deposition.

[0386] (Method for fabricating the light-emitting element 8-1) After forming the electron injection layer 115 of the above-mentioned light-emitting element 8-1, the above-mentioned structural formula (vi) A 2nm layer of copper phthalocyanine (abbreviated as CuPc) is formed, and DBT3P-II and acid The weight ratio of molybdenum(VI) to molybdenum(VI) is 2:1 (=DBT3P-II: molybdenum oxide). A film thickness adjustment layer was formed by co-depositing at 80 nm.

[0387] The element structures of light-emitting element 8 and light-emitting element 8-1 are summarized in the table below.

[0388] [Table 15]

[0389] The light-emitting element 8 and light-emitting element 8-1 are 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, the light-emitting element 8 and the light-emitting element The initial characteristics of 8-1 were measured. The measurements were taken in an atmosphere maintained at 25°C. .

[0390] Figure 46 shows the external quantum efficiency-luminance characteristics of the light-emitting element 8. Brightness of 8-1: 1000 cd / m² 2 Table 16 shows the main characteristics of the vicinity.

[0391] [Table 16]

[0392] Thus, the light-emitting element 8 is a light-emitting element that exhibits very good efficiency with an external quantum efficiency of 31%. This can be seen. Here, the luminescent material used this time is [Ir(tBuppm)2(acac The emission quantum yield (Φ) of )] is known to be 0.91. Carrier balance (γ If the ratio (χ) is 1 and the exciton generation rate (α) is 1, then the light extraction efficiency (χ) is 34.1%. This is calculated to be higher than the generally accepted theoretical value of 20% to 30% for light extraction efficiency. The value is extremely large.

[0393] The light-emitting element 8-1 is an element in which a film thickness adjustment layer is further formed on the light-emitting element 8. By adjusting the length, the light directed towards the front is attenuated, thereby expressing the orientation state. The value of a has been made easier to determine. Note that the configuration and manufacturing method of light-emitting element 8 and light-emitting element 8-1 are also described. In this case, the only difference is the presence or absence of a film thickness adjustment layer, therefore, the orientation of the light-emitting material in the light-emitting layer It can be inferred that the condition is the same.

[0394] Using the light-emitting element 8-1, we investigated the orientation state of the light-emitting material in the light-emitting layer. First, Figure As shown in 20, the substrate on which the light-emitting element 8-1 is provided is used as a detector (manufactured by Hamamatsu Photonics Ltd.) The multi-channel spectrometer PMA-12) is tilted from θ = 0 to 80 degrees, and measurements are taken in 1-degree increments. The EL emission spectrum was measured, and the angular dependence of the spectral shape of the EL emission was measured. In the measurement, a linear polarizer (Grande) is placed perpendicular to the substrate surface between the light-emitting element 8-1 and the detector. A polarizing prism is inserted to remove S-polarized light from the light emitted by the light-emitting element 8-1, and P-polarized light is removed. The spectrum was measured.

[0395] Figure 47 shows the EL emission spectrum from 480 nm to 800 nm at an angle (θ) on the vertical axis. The graph shows the area intensity on the horizontal axis and the detector angle (θ) on the horizontal axis. In the figure, the plots of □ and The graphs shown represent measured values, while the graphs shown with solid or dashed lines represent values ​​obtained using an organic device simulator. This is a calculation result from a certain setfos. The calculation is based on the film thickness of each layer used in the device. , measured values ​​of refractive index and extinction coefficient, measured values ​​of dopant emission spectrum, position of emission region The position, width, and orientation parameters a were input. Among these, the film thickness and refraction of each layer were input. The rate and extinction coefficient were measured using a spectroscopic ellipsometer (M-20, manufactured by J.A. Woolam Japan Co., Ltd.) Measurement was performed using 00U. For the measurement, the material was deposited onto a quartz substrate by vacuum deposition at 150°C. A film with a nm deposition layer was used. The emission spectrum of the dopant was measured using a fluorometer (Hamamatsu Photonics). Measurements were taken using the company's FS920. For the measurement, 4,6 mCzP2Pm and [ The weight ratio of Ir(tBuppm)2(acac) is 1:0.05, and the film thickness is 40 nm. A film co-deposited by vacuum deposition was used. Calculations using setfos showed that Next, the light-emitting region is defined. Here, the interface between the hole transport layer and the light-emitting layer is used as the vertex, The state of the emission region (Gaussian) shows a decay curve where the coupling probability follows a Gaussian function distribution. Assuming that the distance between inflection points of the assumed Gaussian function is 11.5 nm, the emission region is widened. This was set to be the case. As a result, for each parameter a, the area intensity of its emission spectrum The angle dependence in degrees can be calculated. The graph for light-emitting element 8-1 is good when a=0.19. They showed agreement.

[0396] Furthermore, Figure 48 shows the 2D contour plots measuring the angular dependence of the EL emission spectrum of the light-emitting element 8-1. Figure 49 shows the contour plot (measured by actual measurement). Figure 49 also shows the 2D contour plot obtained by calculation. Furthermore, these show good agreement, and this is because the luminescence in this experiment and the calculations are similar. This suggests that the orientation of the light-emitting material in element 8 and light-emitting element 8-1 was accurately determined. ru.

[0397] Here, the value of a when the orientation of the transition dipole is random is 1 / 3 ≈ 0.33, which is completely basic. When the value of a is horizontal to the board, the value of a is 0, and when a=0, the extraction efficiency is a=1 Considering that the light extraction efficiency will be 1.5 times higher when / 3 ≈ 0.33, the a= A light-emitting element with a value of 0.19 has 1.22 times the light absorption capacity of a light-emitting element with random orientation. It can be seen that this is related to output efficiency.

[0398] Furthermore, since the light-emitting element 8 and light-emitting element 8-1 have the same light-emitting layer material and film deposition method, Therefore, the light-emitting element 8, like light-emitting element 8-1, can be said to have an orientation of a = 0.19. Element 8 is a light-emitting element that exhibits a very good external quantum efficiency of 31%, and the value of a is 0.2 or less. It was found that by doing so, a light-emitting element with good luminescence efficiency can be obtained. [Explanation of Symbols]

[0399] 101 First electrode 102 Second electrode 103 EL layer 111 Hole injection layer 112 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 623 n-channel FET 624 p-channel FET 730 Insulating Film 770 Planarizing Insulator 772 Conductive film 782 Light-emitting element 783 Droplet discharge device 784 Droplet 785 layers 786 EL layer 788 Conductive film 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 First electrode of 1024W light-emitting element First electrode of 1024R light-emitting element First electrode of 1024G light-emitting element 1024B First electrode of light-emitting element 1025 Bulkhead 1028 EL layer 1029 Second electrode of light-emitting element 1031 Sealing substrate 1032 Sealant 1033 Transparent base material 1034R Red colored layer 1034G Green colored layer 1034B Blue colored layer 1035 Black Matrix 1037 Third interlayer insulating film 1040 pixel section 1041 Drive circuit section 1042 Peripheral area 1400 Droplet discharge device 1402 circuit board 1403 Droplet discharge means 1404 Imaging means 1405 Head 1406 Dotted line 1407 Control means 1408 Storage medium 1409 Image processing means 1410 Computer 1411 markers 1412 head 1413 Material Source 1414 Material Source 1415 Material Source 1416 Head 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 7401 enclosure 7402 Display section 7403 Operation Buttons 7404 External connection port 7405 Speaker 7406 Microphone 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

1. A first light-emitting layer is provided between the first electrode and the second electrode. The first light-emitting layer has the same configuration as the second light-emitting layer when the value of a measured and calculated using a second light-emitting element having a second light-emitting layer and a film thickness adjustment layer is 0.2 or less. The value of a is the ratio of the z-direction component when the direction of the average transition dipole moment of the light-emitting material in the second light-emitting layer is divided into three mutually orthogonal x, y, and z components, and the components horizontal to the third electrode or fourth electrode of the second light-emitting element are assumed to be in the x and y directions, and the component perpendicular to it is assumed to be in the z direction, in a light-emitting element.

2. Between the first electrode and the second electrode, there is a first light-emitting layer and a first electron transport layer. The first light-emitting layer has the same configuration as the second light-emitting layer when the value of a measured and calculated using a second light-emitting element having a second light-emitting layer and a film thickness adjustment layer is 0.2 or less. The first electron transport layer has a heterocyclic compound, The value of a is the ratio of the z-direction component when the direction of the average transition dipole moment of the light-emitting material in the second light-emitting layer is divided into three mutually orthogonal x, y, and z components, and the components horizontal to the third electrode or fourth electrode of the second light-emitting element are assumed to be in the x and y directions, and the component perpendicular to it is assumed to be in the z direction, in a light-emitting element.

3. In claim 1 or claim 2, A light-emitting element wherein the first light-emitting layer has the same material as the second light-emitting layer, and the concentrations of each material are the same.

4. In any one of claims 1 to 3, The aforementioned film thickness adjustment layer is a layer that adjusts the optical path length in order to attenuate the light directed toward the front of the second light-emitting element, wherein the light-emitting element is a light-emitting element.

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