Light-emitting device, display device, electronic device, and lighting device

Abstract

To provide a light-emitting element with high luminous efficiency.SOLUTION: A light-emitting element has first to third organic compounds. The first organic compound has a function to convert triplet excitation energy into luminescence. The second organic compound has a benzofuropyrimidine or benzothienopyrimidine skeleton. The third organic compound is a fluorescent compound. The luminescence exhibited by the light-emitting element is the luminescence exhibited by the first organic compound or the third organic compound. The third organic compound is provided with excitation energy by an excitation complex formed by the first organic compound and the second organic compound.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] One embodiment of the present invention is a light-emitting element, or a display device, an electronic device, and a lighting device each having the light-emitting element. Regarding the lighting device.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. The technical field of one aspect of the present invention relates to an article, a method, or a manufacturing method. is a process, machine, manufacture, or composition of matter. Therefore, the technical field of one embodiment of the present invention disclosed in the present specification more specifically relates to Examples of the semiconductor device include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, etc. Examples include devices, methods for driving them, and methods for manufacturing them. . [Background technology]

[0003] In recent years, electroluminescence (EL) The basic structure of these light-emitting devices is as follows: The device has a structure in which a layer containing a light-emitting substance (EL layer) is sandwiched between a pair of electrodes. By applying a voltage between them, light is emitted from the luminescent material.

[0004] Since the above-mentioned light-emitting element is a self-luminous type, a display device using the light-emitting element has excellent visibility and backlighting. It has the advantage of not requiring a light source and consuming little power. It also has the advantage of having a high response speed.

[0005] An EL device that uses an organic compound as a light-emitting substance and has the light-emitting organic compound between a pair of electrodes In the case of a light-emitting element having a layer (for example, an organic EL element), a voltage is applied between a pair of electrodes. As a result, electrons are injected from the cathode and holes are injected from the anode into the light-emitting EL layer. The injected electrons and holes are then recombined to produce light-emitting The organic compound is excited, and light can be emitted from the excited luminescent organic compound. do.

[0006] The types of excited states that organic compounds can form include singlet excited states (S * ) and triplet excitation Status(T * ) in which the emission from the singlet excited state is fluorescent and the emission from the triplet excited state is phosphorescent. The statistical generation ratio of these in a light-emitting element is S * :T * = Therefore, compared to a light-emitting element using a compound that emits fluorescence (a fluorescent compound), Light-emitting elements that use compounds that emit phosphorescence (phosphorescent compounds) have higher luminous efficiency. Therefore, it is possible to convert the energy of the triplet excited state into light emission. 2. Description of the Related Art In recent years, light-emitting devices using phosphorescent compounds have been actively developed.

[0007] Among light-emitting elements using phosphorescent compounds, particularly light-emitting elements that emit blue light, It is difficult to develop stable compounds with high triplet excitation energy levels, so they are not yet in practical use. Therefore, efforts are being made to develop light-emitting devices that use more stable fluorescent compounds. Methods to improve the luminous efficiency of light-emitting devices using fluorescent compounds (fluorescent light-emitting devices) are being explored. It has been done.

[0008] One example is thermally activated delayed fluorescence (TDE). Light-emitting devices using TADF (Transparent Anode Fluorescence) materials are known. In thermally activated delayed fluorescent materials, the triplet excited state is converted to the singlet excited state by reverse intersystem crossing. The singlet excited state is converted into light emission.

[0009] In addition, in a light-emitting device having a thermally activated delayed fluorescent material and a fluorescent compound, The singlet excitation energy of the delayed fluorescent material is transferred to the fluorescent compound, and the fluorescent compound emits the A method for obtaining luminescence has been proposed (see Patent Document 1). [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2014-45179 A [Non-patent literature]

[0011] [Non-Patent Document 1] T.Sajoto et al.,J.Am.Chem.Soc.,2009,131,9813 Summary of the Invention [Problem to be solved by the invention]

[0012] In order to increase the luminous efficiency of a fluorescent light-emitting device, it is necessary to efficiently convert the triplet excited state to the singlet excited state. It is preferable that the compound is generated quickly and that the efficiency of energy transfer to the fluorescent material is high. Therefore, the singlet excited state can be efficiently generated from the triplet excited state, and the luminous efficiency of the light-emitting element can be improved. There is a demand for the development of methods and materials that can further improve the light-emitting layer. To reduce the driving voltage, materials with good carrier transport properties are required.

[0013] Therefore, an object of one embodiment of the present invention is to provide a light-emitting element with high emission efficiency. Another object of one embodiment of the present invention is to provide a light-emitting element with low driving voltage. Another object of one embodiment of the present invention is to provide a light-emitting element with high reliability. Another object of one embodiment of the present invention is to provide a light-emitting element with reduced power consumption. Another object of one embodiment of the present invention is to provide a novel light-emitting element. An object of one embodiment of the present invention is to provide a novel light-emitting device. An object of one embodiment is to provide a novel electronic device.

[0014] Note that the above description of the object does not preclude the existence of other objects. It is not necessary to solve all of these problems. Problems other than those mentioned above can be solved by the description of the specification, etc. It is obvious from the description of the specification, etc. that other problems can be extracted. do. [Means for solving the problem]

[0015] As described above, in a light-emitting element that exhibits fluorescence, triplet excitation energy is efficiently converted into light emission. Therefore, the development of a method for converting energy between materials used in the light-emitting layer is required. It is necessary to improve dynamic efficiency.

[0016] Therefore, one embodiment of the present invention is a light-emitting layer between a pair of electrodes, the light-emitting layer containing a first organic compound. a first organic compound, a second organic compound, and a third organic compound, The second organic compound is benzofuropyrimidine, which has the function of converting excitation energy into light emission. The third organic compound has a singlet excited energy The light emitted by the light-emitting layer is the light emitted by the third organic compound. It is a light-emitting element that emits light.

[0017] In the above-mentioned structure, the first organic compound provides excitation energy to the third organic compound. It is preferable that the function be

[0018] Another embodiment of the present invention is a light-emitting layer between a pair of electrodes, the light-emitting layer including a first organic compound. a first organic compound, a second organic compound, and a third organic compound, The first organic compound can form an exciplex with the organic compound, and the first organic compound can emit triplet excited energy. The second organic compound has a benzofuropyrimidine skeleton or The third organic compound has a benzothienopyrimidine skeleton and emits singlet excitation energy. The light emitted by the light-emitting layer has a function of converting light into light, and the light emitted by the light-emitting layer has a function of converting light into light. It is a light-emitting element.

[0019] In the above structure, the exciplex has a function of donating excitation energy to the third organic compound. It is preferable to do so.

[0020] In the above structure, the benzofuropyrimidine skeleton is benzofuro[3,2-d]pyri. The benzothienopyrimidine skeleton is benzothieno[3,2-d]pyrimidine. It is preferable that the skeleton is a diamine skeleton.

[0021] In the above structure, the benzofuro[3,2-d]pyrimidine skeleton or the benzothieno It is preferred that the [3,2-d]pyrimidine skeleton has a substituent at the 4- or 8-position.

[0022] In the above-mentioned structure, the first organic compound is Ru, Rh, Pd, Os, Ir, or It is preferable that the metal oxide layer comprises Pt.

[0023] In the above structure, the first organic compound preferably exhibits phosphorescence.

[0024] In the above structure, the emission spectrum of the exciplex is similar to that of the absorption spectrum of the third organic compound. It is preferable that the absorption band has a region overlapping with the absorption band on the longest wavelength side of the absorption spectrum.

[0025] In the above-mentioned configuration, the first organic compound has a luminescence quantum yield of 0% or more and 40% or less at room temperature. It is preferred to have a high yield.

[0026] In the above structure, the exciplex has a higher luminous efficiency than the luminescence efficiency of the first organic compound. It is preferable that the light emitting element has a function of emitting light with high luminous efficiency.

[0027] In the above structure, it is preferable that the third organic compound exhibits fluorescence.

[0028] In the above-mentioned configuration, the singlet excitation energy and the triplet excitation energy of the first organic compound are The energy difference between the energies is preferably 0 eV or more and 0.2 eV or less.

[0029] Another embodiment of the present invention is a light-emitting element having any of the above structures, and a color filter or a transistor. and at least one of a first transistor and a second transistor. The electronic device has the display device and at least one of a housing and a touch sensor. Another embodiment of the present invention is a display device including a light-emitting element having any of the above structures and at least one housing or a touch sensor. Another embodiment of the present invention is a lighting device having a light-emitting element. The term "light emitting device" includes not only optical devices but also electronic devices having light emitting devices. The light-emitting device in this specification refers to an image display device or a light source (including a lighting device). Connectors for optical elements, such as FPC (Flexible Printed Circuit) t), TCP (Tape Carrier Package) mounted display module A display module with a printed wiring board at the end of the TCP, or a light-emitting element with C Display with IC (integrated circuit) directly mounted using OG (Chip On Glass) method The module may also be included in the light emitting device. Effect of the Invention

[0030] According to one embodiment of the present invention, a light-emitting element with high emission efficiency can be provided. According to one embodiment of the present invention, a light-emitting element with low driving voltage can be provided. According to one embodiment of the present invention, a light-emitting element with high reliability can be provided. According to one embodiment of the present invention, a light-emitting element with reduced power consumption can be provided. According to one embodiment of the present invention, a novel light-emitting element can be provided. According to the above, a novel light-emitting device can be provided. Thus, a novel electronic device can be provided.

[0031] Note that the description of these effects does not preclude the existence of other effects. It is not necessary to have all of these effects. Effects other than these are described in the specification. The disclosure of the specification, drawings, claims, etc. is self-evident, and the disclosure of the specification, drawings, claims, etc. is self-evident. From this, it is possible to extract other effects. [Brief description of the drawings]

[0032] [Figure 1] 1A and 1B are schematic cross-sectional views of a light-emitting element of one embodiment of the present invention and a diagram illustrating the correlation between energy levels of a light-emitting layer. [Diagram 2] 1A and 1B are diagrams illustrating the correlation between energy levels of a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Diagram 3] 1A and 1B are diagrams illustrating the correlation between energy levels of a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Figure 4] 1A and 1B are diagrams illustrating the correlation between energy levels of a light-emitting layer of a light-emitting element according to one embodiment of the present invention. [Diagram 5] 1 is a schematic cross-sectional view of a light-emitting element according to one embodiment of the present invention. [Figure 6] 1A and 1B are a top view and a cross-sectional schematic diagram illustrating a display device of one embodiment of the present invention. [Figure 7] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 8] 1A and 1B are schematic cross-sectional views illustrating a display device according to one embodiment of the present invention. [Figure 9] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Figure 10] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Figure 11] 1A to 1C illustrate electronic devices of one embodiment of the present invention. [Figure 12] 1A to 1C are diagrams illustrating a lighting device according to one embodiment of the present invention. [Figure 13] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 14] FIG. 13 is a graph showing current-voltage characteristics of a light-emitting element in the embodiment. [Figure 15] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 16] 1A and 1B are diagrams illustrating emission spectra of light-emitting elements in accordance with an embodiment. [Figure 17] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Figure 18] FIG. 13 is a graph showing current-voltage characteristics of a light-emitting element in the embodiment. [Figure 19] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 20] 1A and 1B are diagrams illustrating emission spectra of light-emitting elements in accordance with an embodiment. [Figure 21] FIG. 13 is a diagram illustrating the results of time-resolved luminescence measurement in the examples. [Figure 22] FIG. 4 is a diagram illustrating the relationship between an emission spectrum and an absorption spectrum in the example. [Diagram 23] FIG. 11 is a diagram for explaining reliability test results according to the embodiment. [Figure 24] FIG. 13 is a graph showing current efficiency vs. luminance characteristics of a light-emitting element in the embodiment. [Diagram 25] FIG. 13 is a graph showing current-voltage characteristics of a light-emitting element in the embodiment. [Figure 26] FIG. 13 is a graph showing external quantum efficiency vs. luminance characteristics of a light-emitting element according to an embodiment. [Figure 27] 1A and 1B are diagrams illustrating emission spectra of light-emitting elements in accordance with an embodiment. [Figure 28] FIG. 4 is a diagram illustrating the relationship between an emission spectrum and an absorption spectrum in the example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the above description, and the embodiments and details thereof are not limited to those described above without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the following embodiments and examples. The present invention should not be construed as being limited to the contents of the examples.

[0034] In addition, the position, size, range, etc. of each component shown in the drawings are not necessarily shown in order to facilitate understanding. The actual position, size, range, etc. may not be shown. The present invention is not necessarily limited to the position, size, range, etc. disclosed in the drawings, etc.

[0035] In addition, in this specification, ordinal numbers such as 1st, 2nd, etc. are used for convenience. In some cases, the order of steps or layers may not be indicated. For example, "first" may be replaced with "second" or " " can be appropriately replaced with "the third" etc. The ordinal numbers used to identify an aspect of the present invention may not match those used in the present invention. be.

[0036] In addition, in this specification and the like, when explaining the configuration of the invention using drawings, The reference numerals may be commonly used among different drawings.

[0037] In addition, in this specification and the like, the terms "film" and "layer" are interchangeable. For example, the term "conductive layer" can be changed to the term "conductive film." Alternatively, for example, the term "insulating film" may be changed to "insulating layer." It may be possible to change the term to:

[0038] In the present specification and the like, the singlet excited state (S * ) is a single charge with excitation energy The S1 level is the lowest singlet excited energy level. , the lowest excited energy level of the singlet state (S1 state). term excited state (T * ) is a triplet state with an excited energy. The lowest triplet excited energy level is the lowest triplet excited state (T1 In this specification and the like, the term "singlet excited state" refers to the excited energy level of the singlet excited state. Even when written as states and singlet excited energy levels, the S1 state and S1 level The triplet excited state and triplet excited energy level are also used. Even in this case, it may refer to a T1 state and a T1 level.

[0039] In the present specification and the like, a fluorescent compound refers to a compound that relaxes from a singlet excited state to a ground state. Phosphorescent compounds are compounds that emit light in the visible light region when emitted from a triplet excited state. It is a compound that emits light in the visible light region at room temperature when it relaxes to the bottom state. A phosphorescent compound is one of the compounds that can convert triplet excitation energy into visible light.

[0040] In this specification and the like, room temperature refers to a temperature in the range of 0°C or higher and 40°C or lower.

[0041] In this specification, the blue wavelength range is from 400 nm to less than 490 nm. The blue light emission has at least one emission spectrum peak in the wavelength region. The green wavelength region is 490 nm or more and less than 580 nm, and green emission is within this wavelength region. It has at least one emission spectrum peak. The red wavelength region is 580 nm. and the red emission has at least one emission spectrum in the wavelength range. It has a peak.

[0042] (Embodiment 1) In this embodiment, a light-emitting element of one embodiment of the present invention will be described below with reference to FIGS. Reveal.

[0043] <Configuration example 1 of light-emitting element> First, a structure of a light-emitting element of one embodiment of the present invention will be described below with reference to FIG.

[0044] FIG. 1A is a schematic cross-sectional view of a light-emitting element 150 of one embodiment of the present invention.

[0045] The light emitting element 150 has a pair of electrodes (electrode 101 and electrode 102). The EL layer 100 includes at least a light-emitting layer 130. .

[0046] The EL layer 100 shown in FIG. 1A includes a hole injection layer 111, a hole injection layer 112, a light emitting layer 130, and a cathode. It has functional layers such as a hole transport layer 112 , an electron transport layer 118 , and an electron injection layer 119 .

[0047] In this embodiment, of the pair of electrodes, electrode 101 is an anode, and electrode 1 Although the description will be given assuming that 02 is a cathode, the configuration of the light-emitting element 150 is not limited to this. The electrode 101 is a cathode, the electrode 102 is an anode, and the layers between the electrodes are stacked in the reverse order. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, and the light emitting layer 113 may be arranged in that order. The light-emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be laminated in this order. .

[0048] The configuration of the EL layer 100 is not limited to the configuration shown in FIG. 1(A). At least one selected from the group consisting of a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119. Alternatively, the EL layer 100 may be a hole or electron injector. Reduce the barrier, improve the transportability of holes or electrons, or inhibit the transportability of holes or electrons. or suppressing the quenching phenomenon caused by the electrode. Each functional layer may be a single layer or a laminate of multiple layers. It may be composed of

[0049] Next, the light emitting layer 130 will be described below.

[0050] In one embodiment of the present invention, the light-emitting device 150 has a fluorescent compound in the light-emitting layer 130. The fluorescent light-emitting element has good reliability and has an emission spectrum similar to that of phosphorescence. Since the color tends to be sharper than that of light-emitting elements, it is possible to obtain light-emitting elements with high color purity. However, in the case of organic EL devices, the generation ratio of singlet excitons and triplet excitons (hereafter referred to as exciton The probability of singlet exciton generation is 1:3 due to statistical probability. In a fluorescent light-emitting device that uses luminescence, only 25% of the generated excitons can contribute to luminescence. Therefore, in order to increase the efficiency of fluorescent light-emitting devices, it is important to make triplet excitons contribute to light emission. It is essential.

[0051] Here, the present inventors have used an organic compound capable of converting triplet excitation energy into light emission in the light-emitting layer. An organic compound having a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton and a fluorescent By using organic compounds that exhibit photoluminescence, triplet excitons can be efficiently converted into fluorescence. In other words, it has been found that a highly efficient fluorescent element can be obtained.

[0052] The above-mentioned benzofuropyrimidine skeleton or benzothienopyrimidine skeleton is a benzofuro[3 ,2-d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton. This structure can improve the electron transport property of the organic compound. The LUMO (Lowest Unoccupied Molecular Weight) of the organic compound Orbital (also called the lowest unoccupied orbital) level is lowered, so that the This makes it easier for the organic compound to receive electrons, and the driving voltage of the light-emitting device can be reduced.

[0053] In addition, the benzofuro[3,2-d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton It is preferable that the lysidine skeleton has a substituent at the 4-position and / or the 8-position. In this way, a light-emitting element with high luminous efficiency and high reliability can be obtained.

[0054] The substituent at the 4-position and / or 8-position is preferably a substituent having a hole transporting skeleton. Specifically, for example, a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, Examples of such structures include the cyclic amine skeleton.

[0055] The above-mentioned organic compound having a function of converting triplet excitation energy into light emission. Examples of such compounds include compounds that can emit phosphorescence (hereinafter, also referred to as phosphorescent compounds). In this specification, the term "phosphorescent compound" refers to a compound that emits light in a temperature range of from a low temperature (e.g., 77 K) to room temperature. (i.e., 77K or higher and 313K or lower) Phosphorescent compounds are compounds that do not efficiently convert triplet excitation energy into light. In order to convert the phosphorescent compound, it is preferable to have a heavy atom. The spin-orbit interaction (interaction between the spin angular momentum of the electron and the orbital angular momentum) Transitions between the ground state and the triplet excited state are allowed. The transition probability between the triplet excited state and the triplet excited state is increased, so the efficiency and In addition, the triplet excitation energy of the phosphorescent compound can be increased. -level to the singlet excited energy level of a fluorescent compound by the Förster mechanism Energy transfer is also permitted. To achieve this, the phosphorescent compound must have a large spin-orbit coupling. It is preferable that the alloy contains a metal element having a low molecular weight, specifically, a transition metal element, and particularly, a platinum group element ( Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Osmium (Os), It is preferable that the metal oxide has iridium (Ir) or platinum (Pt), among which iridium is preferably used. By having the above structure, the transition probability for the direct transition between the singlet ground state and the triplet excited state can be increased. This is preferable.

[0056] In addition, materials that have the function of converting triplet excitation energy into luminescence include and thermally activated delayed fluorescence (TADF) materials. The difference between the S1 and T1 levels is small, and the triplet excitation energy can be converted to singlet excitation energy by reverse intersystem crossing. It is a material that has the function of converting energy into excitation energy. Therefore, the triplet excitation energy is converted to singlet excitation energy by a small amount of thermal energy. It is possible to efficiently generate singlet excited states by reverse intersystem crossing. Excited states are formed by two types of substances called exciplexes. The difference between the S1 and T1 levels is extremely small. Thermally activated delayed fluorescence capable of converting triplet excitation energy into singlet excitation energy It has a material function.

[0057] FIG. 1(B) is a schematic cross-sectional view showing an example of the light-emitting layer 130 shown in FIG. The light-emitting layer 130 shown in FIG. 1B contains compounds 131, 132, and 133. In one embodiment of the present invention, compound 131 is capable of converting triplet excitation energy into luminescence. Compound 132 has a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton. Compound 133 is an organic compound with a lysidine skeleton. Compound 133 is a guest material that exhibits fluorescent emission. It is.

[0058] <Emitting layer configuration example 1> FIG. 1C illustrates one example of the correlation of energy levels in a light-emitting layer in a light-emitting element of one embodiment of the present invention. In this configuration example, a phosphorescent compound is used as the compound 131.

[0059] In addition, the compounds 131, 132, and 133 in the light-emitting layer 130 The correlation between the energy levels is shown in Figure 1(C). The notations and symbols in Figure 1(C) are as follows: As shown below. ·Comp(131): Compound 131 ·Comp(132): Compound 132 ·Guest(133): Compound 133 T C1 :T1 level of compound 131 ·S C2 : S1 level of compound 132 T C2 :T1 level of compound 132 ·S G : S1 level of compound 133 T G :T1 level of compound 133

[0060] In Figure 1(C), compound 131 or compound 132 accepts holes and electrons. Here, compound 131 is a phosphorescent compound, so it forms a singlet state and a triplet state. Intersystem crossing between the singlet state and the 132 singlet excited energy is therefore Both the triplet excitation energy and the triplet excitation energy can be rapidly transferred to compound 131 (Figure 1). 1(C) Root A1). In this case, S C2 ≧T C2 , T C2 ≧T C1 It is preferable that The light-emitting layer 130 is formed by mixing compounds 131, 132, and 133. However, it is preferable that the mixture ratio of compound 131 and compound 132 is higher than that of compound 132. Specifically, the weight ratio of Compound 131:Compound 132 is preferably from 1:9 to 3:7. This configuration allows compound 131 to be excited efficiently. Since 31 is a phosphorescent compound, it can efficiently utilize the triplet excitation energy of compound 131. The singlet excitation energy of compound 133 can be converted to the singlet excitation energy of compound 133 (Figure 1(C) Route A 2) Here, as shown in Figure 1(C), S C2 ≧T C1 ≧S G If so, the singlet excited This is preferable because the energy is efficiently transferred to the guest material, compound 133. C 2 ≧ T C1 ≧S G When the triplet excitation energy is converted to singlet excitation energy efficiently, This is favorable for migration to the guest material, compound 133.

[0061] Also, T C1 From T G When triplet excited energy transfer occurs to is inactivated (Fig. 1(C) Route A3). Therefore, the energy transfer of Route A3 The less the better. To suppress the energy transfer of route A3, compound 131 and The weight ratio of the total amount of compound 132 to compound 133 is low. Preferably, the weight of compound 133 relative to the total amount of compound 131 and compound 132 is The ratio is preferably 0.001 or more and 0.05 or less, and more preferably 0.001 or more and 0.05 or less. It is less than .01.

[0062] In addition, when the direct recombination process of carriers becomes dominant in compound 133, compound 13 In 3, a large number of triplet excitons are generated, and the emission efficiency is reduced due to thermal deactivation. Therefore, route A is preferred over the direct recombination of carriers in compound 133. The higher the ratio of the energy transfer process via 2, the higher the probability of generating the triplet excited state of compound 133. This is preferable because it is possible to reduce the rate of oxidation and suppress thermal deactivation. The weight ratio of the total amount of Compound 131 and Compound 132 to Compound 133 is It is preferable that the ratio is low, specifically, the ratio of compound 131 to the total amount of compound 132. The weight ratio of the substance 133 is preferably 0.001 or more and 0.05 or less, more preferably 0. Greater than or equal to .001 and less than or equal to 0.01.

[0063] By configuring the light-emitting layer 130 as described above, light emitted from the fluorescent compound in the light-emitting layer 130 can be efficiently emitted. You can get it at a good rate.

[0064] Also, T G It is preferable that the wavelength is 2.0 eV or less. By adopting this configuration, the light emission with good reliability can be achieved. The element can be obtained.

[0065] In the above configuration, it is not necessary to use a material with a high luminescence quantum yield as the phosphorescent compound. This makes it easier to design materials, and the range of material options is broadened. At room temperature or normal temperature, it may be 0% or more and 50% or less, and 0% or more and 40% or less It may be 0% or more and 25% or less, or it may be 0% or more and 10% or less. Furthermore, it may be 0% or more and 1% or less.

[0066] As described above, the compound having a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton is Among organic compounds, benzofuro[3,2-d]pyrimidine skeleton or benzothieno[3,2- d] Organic compounds with a pyrimidine skeleton have a low LUMO level. The compound can be suitably used as compound 132 having an electron transporting property.

[0067] <Emitting layer configuration example 2> FIG. 2B shows the energy levels in the light-emitting layer 130 of the light-emitting element 150 of one embodiment of the present invention. In this configuration example, a phosphorescent compound is used as compound 131, and This shows the case where compound 132 forms an exciplex.

[0068] The combination of Compound 131 and Compound 132 is a combination capable of forming an exciplex. However, one of the compounds may be a compound having a hole transporting property and the other a compound having an electron transporting property. In this case, it is more preferable that the compound is a donor-acceptor type exciplex. This makes it easier to form the compound 131, which allows for efficient formation of the exciplex. The combination with compound 132 is a compound having hole transport properties and a compound having electron transport properties. In the case of a combination of these, the carrier balance can be easily controlled by the mixture ratio. Specifically, the compound having hole transporting property: the compound having electron transporting property=1 The weight ratio is preferably in the range of 9:9 to 9:1. Since the rear balance can be controlled, the carrier recombination region can be easily controlled. It is possible.

[0069] The formation of the exciplex can be seen, for example, in the emission spectrum of compound 131 and the emission spectrum of compound 132. The emission spectra of the mixed films were compared to those of the mixed films. The emission spectrum is shifted to longer wavelengths than the emission spectrum of each compound (or This can be confirmed by observing the phenomenon of a new peak on the side of the Transient photoluminescence (PL) of compound 131, transient PL of compound 132, and The transient PL lifetime of the mixed film was compared, and the transient PL lifetime of the mixed film was compared. Transient PL lifetimes that have components longer than the transient PL lifetime or have a large proportion of delayed components This can be confirmed by observing the difference in the response.

[0070] In addition, the combination of compounds 131 and 132 is an example of a combination of materials that efficiently form an exciplex. One of the HOMOs (Highest Occupied Molecule) of the substance 132 r Orbital (also called the highest occupied molecular orbital) level is higher than the HOMO level of the other It is preferable that the LUMO level of the compound 13 is higher than the LUMO level of the other compound. The energy difference between the HOMO level of 1 and the HOMO level of compound 132 is preferably 0.1 eV or more, more preferably 0.2 eV or more, and even more preferably 0.3 eV or more. In addition, the energy difference between the LUMO level of compound 131 and the LUMO level of compound 132 is The energy difference is preferably 0.1 eV or more, more preferably 0.2 eV or more, and More preferably, it is 0.3 eV or more. By making such an energy level correlation, Carriers, that is, holes and electrons, are injected from a pair of electrodes (electrodes 101 and 102). However, it is preferable that the compound 131 and the compound 132 are easily injected. , the HOMO level of compound 131 is equal to the HOMO level of compound 132, or The LUMO level of 1 may be equivalent to the LUMO level of compound 132.

[0071] The LUMO and HOMO levels of the compounds were determined by cyclic voltammetry (C V) Derived from the electrochemical properties (reduction potential and oxidation potential) of the compound measured by the measurement It is possible.

[0072] For example, when compound 131 has a hole transporting property and compound 132 has an electron transporting property, As shown in the energy band diagram in Figure 2(A), the HOMO level of compound 131 is The HOMO level of compound 131 is preferably higher than the HOMO level of compound 32, and the LUMO level of compound 131 is preferably higher than the HOMO level of compound 13. It is preferable that the LUMO level of the 2-nuclear molecule is higher than that of the 2-nuclear molecule. The carriers injected from the pair of electrodes (electrodes 101 and 102) are holes and This is preferable because electrons can be easily injected into compound 131 and compound 132, respectively.

[0073] In FIG. 2(A), Comp(131) represents compound 131, and Comp(1 32) represents compound 132, ΔE C1 are the LUMO and HOMO levels of compound 131 and represents the energy difference, ΔE C2 is the energy between the LUMO and HOMO levels of compound 132. represents the energy difference, and ΔE E is the LUMO level of compound 132 and the HOMO level of compound 131. are the notation and symbol representing the energy difference between

[0074] In addition, the exciplex formed by compound 131 and compound 132 has a HOMO and compound 132 becomes an exciplex having a LUMO molecular orbital. The excitation energy of the exciplex is the LUMO level of compound 132 and the HOMO level of compound 131. Energy difference between the levels (ΔE E ) and the LUMO and HOMO levels of compound 131 are Energy difference between the levels (ΔE C1 ) and the relationship between the LUMO and HOMO levels of compound 132 Energy difference (ΔE C2 ) is smaller than that of Compound 131 and Compound 132. By forming an exciplex at , it is possible to form an excited state at a lower excitation energy. In addition, since the excitation energy is lower, the exciplex has a stable excited state. It can be formed.

[0075] In addition, the compounds 131, 132, and 133 in the light-emitting layer 130 The correlation between the energy levels is shown in Figure 2(B). The notations and symbols in Figure 2(B) are as follows: The other notations and symbols are the same as those shown in FIG. 1(C). ·S C1 : S1 level of compound 131 ·S E : S1 level of the exciplex T E :T1 level of the exciplex

[0076] In the light-emitting element of one embodiment of the present invention shown in this configuration example, the compound contained in the light-emitting layer 130 Compound 131 and compound 132 form an exciplex. The S1 level of the exciplex (S E ) and exciplexes T1 level (T E ) are adjacent energy levels (Figure 2(B) Route A See 4).

[0077] The exciplexes formed by the above process can emit light or transfer the excitation energy to other materials. When an electron goes to the ground state by losing excitation energy, such as by donating it to a nucleon, it forms an exciplex. The two substances that were once separated will once again behave as separate substances.

[0078] Excitation energy levels of exciplexes (S E and T E ) is a compound that forms an exciplex. The S1 levels (S C1 and S C2 ) is lower, It is possible to form an excited state with lower excitation energy. This allows the luminescent element The driving voltage of the element 150 can be reduced.

[0079] The S1 level of the exciplex (S E ) and T1 level (T E ) are adjacent energy levels Therefore, the exciplex has the function of exhibiting thermally activated delayed fluorescence. It has the function of converting energy into singlet excitation energy by upconversion. Therefore, a part of the triplet excitation energy generated in the light-emitting layer 130 is absorbed by the exciplex. To do this, the S1 level (S E ) and T1 standard Place(T E The energy difference between the two is preferably greater than 0 eV and less than 0.2 eV, more preferably The electron energy is preferably greater than 0 eV or less than 0.1 eV. To do this, the T1 level of the exciplex (T E ) are each compound that forms an exciplex (compound 131 and and compound 132) T1 level (T C1 and T C2 ) is preferable. The triplet excitation energy of the exciplexes by compounds 131 and 132 was quenched by The exciplex efficiently converts triplet excitation energy into singlet excitation energy. Reverse intersystem crossing to the energy occurs.

[0080] In addition, the singlet excited energy level of the exciplex (S E ) is a light-emitting material, compound 133 The singlet excited energy level (S G ) is preferable. By assuming a correlation between the positions, the singlet excitation energy of the generated exciplex is Excitation energy level (S E ) to the singlet excited energy level (S G )Hehe Energy can be transferred.

[0081] In this case, the correlation between the energy levels of compounds 131 and 132 is limited to that shown in FIG. 2(B). That is, the singlet excited energy level (S C1 ) is a compound The singlet excited energy level of 132 (S C2 ) may be higher or lower. The triplet excited energy level of 131 (T C1 ) is the triplet excitation energy of compound 132 Level (T C2 ) may be higher or lower.

[0082] In one embodiment of the present invention, a phosphorescent compound is added to one of the compounds forming the exciplex. Because of this, intersystem crossing between the singlet and triplet states is permitted. It is possible to form an exciplex that can undergo a transition from an excited state to a singlet ground state. In this case, the triplet excited energy level of the exciplex (T E ) is one of the light-emitting materials, compound 133. Singlet excited energy level (S G ) is preferable. By correlating the triplet excitation energy of the generated exciplex, Energy Level (T E ) to the singlet excited energy level (S G ) to Energy In addition, the S1 level (S E ) and T1 level (T E )teeth, Because the energy levels are adjacent to each other, the emission spectrum clearly shows fluorescence and phosphorescence. In some cases, it may be difficult to distinguish between fluorescence and phosphorescence. It may be possible to distinguish.

[0083] Through the energy transfer process described above, compound 133 enters a singlet excited state and emits light. (See route A5 in Figure 2(B)).

[0084] Also, T E From T G When triplet excitation energy transfer occurs to The enzyme is inactivated (Fig. 2(B) Route A6). Therefore, the energy transfer along Route A6 is small. In order to suppress the energy transfer of route A6, compounds 131 and The weight ratio of the total amount of compound 132 to compound 133 is preferably low. More specifically, the weight ratio of compound 133 to the total amount of compound 131 and compound 132 is preferably is preferably 0.001 or more and 0.05 or less, and more preferably 0.001 or more and 0. 01 or less.

[0085] In addition, when the direct recombination process of carriers becomes dominant in compound 133, compound 13 In 3, a large number of triplet excitons are generated, and the emission efficiency is reduced due to thermal deactivation. Therefore, rather than a direct recombination process of carriers in compound 133, the exciplex The higher the ratio of the energy transfer process via the formation process of 1, the greater the reaction rate. The probability of generating the triplet excited state of compound 133 can be reduced, and thermal deactivation can be suppressed. For this purpose, the total amount of Compound 131 and Compound 132 and the total amount of Compound 13 are preferably The weight ratio of compound 133 to compound 131 is preferably low. The weight ratio of compound 133 to the total amount of compound 132 is preferably 0.001 or more and It is 0.05 or less, and more preferably between 0.001 and 0.01.

[0086] Also, T G It is preferable that the wavelength is 2.0 eV or less. By adopting this configuration, the light emission with good reliability can be achieved. The element can be obtained.

[0087] Note that compound 131 has an electron transporting property, and compound 132 has a hole transporting property. In this case, the HOMO level of compound 132 may be higher than the HOMO level of compound 131. It is preferable that the LUMO level of compound 132 is higher than the LUMO level of compound 131. It is preferable that

[0088] In addition, the weight ratio of compound 131 to compound 132 is low. It is preferred that the weight ratio of compound 131 to compound 132 is preferably 0.0 The ratio is 1 or more and 0.5 or less, and more preferably 0.05 or more and 0.3 or less.

[0089] As described above, all of the energy transfer processes in routes A4 and A5 described above occur efficiently. For example, both the singlet excitation energy and the triplet excitation energy generated in the light-emitting layer 130 can be efficiently used. Since the energy of the singlet excited state of compound 133 is efficiently converted into the energy of the singlet excited state of compound 133, the light-emitting element 150 It becomes possible to emit light with high luminous efficiency.

[0090] In addition, in the light-emitting element of one embodiment of the present invention, The pyrimidine or benzothienopyrimidine skeleton is a benzofuro[3,2-d]pyrimidine derivative. It is preferable that the structure is a pyrimidine skeleton or a benzothieno[3,2-d]pyrimidine skeleton. This lowers the LUMO level of compound 132, making it favorable for the formation of an exciplex.

[0091] In addition, the benzofuro[3,2-d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton It is preferable that the lysidine skeleton has a substituent at the 4-position and / or the 8-position. , the LUMO level of compound 132 is lowered and favors the formation of an exciplex.

[0092] The above-mentioned processes of routes A4 and A5 are referred to as ExSET (ExcSET) in this specification. iplex-Singlet Energy Transfer) or ExEF (Ex This is sometimes called ciplex-Enhanced Fluorescence. In other words, the light-emitting layer 130 is formed by providing excitation energy from an exciplex to a fluorescent compound. do.

[0093] By configuring the light-emitting layer 130 as described above, light emission from the fluorescent compound can be obtained efficiently. can be done.

[0094] <Emitting layer configuration example 3> FIG. 3 is an example of the correlation of energy levels in a light-emitting layer in a light-emitting element according to one embodiment of the present invention. In this configuration example, a thermally activated delayed fluorescent material is used as the compound 131. The notations and symbols in Fig. 3 are the same as those shown in Fig. 1(C). ·S C1 : S1 level of compound 131

[0095] In Figure 3, compound 131 or compound 132 receives a hole and an electron to produce an excited state. In addition, the excitation energy of compound 132 is rapidly transferred to compound 131. (Route A7). At this time, S C2 ≧S C1 , T C2 ≧T C1 I would like to Here, the light-emitting layer 130 is a mixture of compounds 131, 132, and 133. However, it is preferable that the mixture ratio of compound 131 and compound 132 is higher than that of compound 132. Specifically, the weight ratio of Compound 131:Compound 132 is preferably 1:9 to 3:7. This configuration is preferable. Compound 131 can be excited efficiently. Since compound 131 is a thermally activated delayed fluorescent material, the triplet excited electrons of compound 131 are The energy is up-converted to singlet excitation energy at room temperature (Lu In addition, the singlet excited energy level of compound 131 (S C1 ) to compound 133 The singlet excited energy level (S G ) (route A9) is allowed, Therefore, the triplet excited energies of compound 131 can be obtained by the processes of Route A8 and Route A9. The energy was calculated by the singlet excited energy level (S G ) energy transfer to Here, as shown in Figure 3, T C2 ≧T C1 ≧S GThe singlet excitation energy is Both the energy and triplet excitation energy were efficiently extracted from compounds 131 and 132. This is preferred because it transfers to the starting material, compound 133.

[0096] In order to efficiently proceed with the above-mentioned upconversion, the thermally activated delayed fluorescence material S 1 level (S C1 ) and T1 level (T C1 The energy difference between the The excitation voltage is preferably less than 0.2 eV, and more preferably more than 0 eV and less than 0.1 eV.

[0097] Also, T C2 From T G When triplet excitation energy transfer occurs to (Fig. 3 Route A 10 ) Therefore, root A 10 There is little energy transfer Route A is preferable. 10 In order to suppress the energy transfer of T C1 and T G With A larger energy difference is preferable. To achieve this, T G is preferably 2.0 eV or less. By using such a structure, a light-emitting element having high luminous efficiency and high reliability can be obtained. .

[0098] By configuring the light-emitting layer 130 as described above, light emitted from the fluorescent compound in the light-emitting layer 130 can be efficiently emitted. You can get it at a good rate.

[0099] <Emitting layer configuration example 4> FIG. 4A shows a case where four kinds of materials are used for the light-emitting layer 130. In the light-emitting layer 130, compound 131, compound 132, compound 133, and compound 134 are In one embodiment of the present invention, compound 131 converts triplet excitation energy into luminescence. Compound 132 has a benzofuropyrimidine skeleton or a benzothiene skeleton. Compound 133 is an organic compound that has a pyrimidine skeleton. Compound 134 is an organic compound that forms an exciplex with compound 132. .

[0100] In addition, the compounds 131, 132, and 133 in the light-emitting layer 130 are The energy level correlation of the substance 134 is shown in FIG. 4(B). The symbols and notations are as follows, and the other symbols and notations are the same as those shown in FIG. 2(B). Same here. ·S C3 : S1 level of compound 134 T C3 :T1 level of compound 134

[0101] In the light-emitting element of one embodiment of the present invention shown in this configuration example, the compound contained in the light-emitting layer 130 Compound 132 forms an exciplex with compound 134. The S1 level of the exciplex (S E ) and exciplexes T1 level (T E ) are adjacent energy levels (Figure 4(B) Route A 11 reference).

[0102] The exciplexes formed by the above process lose their excitation energy, as described above. The two substances that formed the exciplex then behave as if they were separate substances again.

[0103] Excitation energy levels of exciplexes (S E and T E ) is a compound that forms an exciplex. The S1 levels (SC2 and S C3 ) is lower, It is possible to form an excited state with lower excitation energy. This allows the luminescent element The driving voltage of the element 150 can be reduced.

[0104] Here, since compound 131 is a phosphorescent compound, the intersystem between the singlet state and the triplet state is Crossover is allowed. Therefore, the singlet excitation energy and triplet excitation energy of the exciplex are Both the energy and the cations are rapidly transferred to compound 131 (Route A). 12 ). At this time, T E ≧T C1 In addition, the triplet excitation energy of compound 131 can be efficiently converted to The singlet excitation energy of compound 133 can be converted directly into the singlet excitation energy of compound 133 (Route A). 13 ).child As shown in FIG. 4(B), T E ≧T C1 ≧S G Then, the excitation energy of compound 131 is The energy is efficiently transferred to the guest material, compound 133, as singlet excitation energy. Therefore, it is preferable.

[0105] In this case, the combination of Compound 132 and Compound 134 can form an exciplex. Any possible combination is acceptable, but one of them is a compound having hole transport properties and the other is an electron It is more preferable that the compound has a transport property. In this case, the compound is a donor-acceptor type. This makes it easier to form an exciplex, and the exciplex can be formed efficiently. The combination of Compound 132 and Compound 134 is a compound having hole transport properties and a compound having electron transport properties. When a compound that can be used in combination with a carrier is used, the carrier balance can be easily controlled by changing the mixture ratio. Specifically, a compound having a hole transporting property and a compound having an electron transporting property can be The compound ratio is preferably in the range of 1:9 to 9:1 (weight ratio). Since the carrier balance can be easily controlled, the carrier recombination region can also be controlled. It can be done easily.

[0106] In addition, the combination of compounds 132 and 133 is an example of a combination of materials that efficiently forms an exciplex. One HOMO level of the compound 134 is higher than the other HOMO level, and one LUMO level It is preferable that the HOMO level of compound 132 is higher than the LUMO level of the other compound. The energy difference between the level and the HOMO level of compound 134 is preferably 0.1 eV or more. More preferably, it is 0.2 eV or more, and even more preferably, it is 0.3 eV or more. The energy difference between the LUMO level of compound 132 and the LUMO level of compound 134 is preferably or 0.1 eV or more, more preferably 0.2 eV or more, and further preferably By making the energy level correlation in this way, Carriers, ie, holes and electrons, injected from the electrode 101 and the electrode 102 are transferred to compound 13. Compound 132 and Compound 134 are suitable for injection. The HOMO level of compound 134 is equal to the HOMO level of compound 134, or the LUMO level of compound 132 is equal to the HOMO level of compound 134. The LUMO level of the compound 134 may be equivalent to that of the compound 134.

[0107] In addition, the correlation between the energy levels of compounds 132 and 134 is not limited to that shown in FIG. 4(B). That is, the singlet excited energy level (S C2 ) is compound 13 The singlet excited energy level of 4 (S C3) may be higher or lower than that of compound 13. The triplet excited energy level of 1 (T C1 ) is the triplet excited energy level of compound 134 (T C3 ) may be higher or lower.

[0108] In addition, in the light-emitting element of one embodiment of the present invention, The pyrimidine or benzothienopyrimidine skeleton is a benzofuro[3,2-d]pyrimidine It is preferable that the structure is a benzothieno[3,2-d]pyrimidine skeleton. This lowers the LUMO level of compound 132, making it favorable for the formation of an exciplex.

[0109] In addition, the benzofuro[3,2-d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton It is preferable that the lysidine skeleton has a substituent at the 4-position and / or the 8-position. , the LUMO level of compound 132 is lowered and favors the formation of an exciplex.

[0110] Also, T C1 From T G When triplet excited energy transfer occurs to is inactivated (Figure 4(B) Route A 14 ) Therefore, root A 14 Energy transfer Less movement is preferable. Route A 14 In order to suppress the energy transfer of 31, the weight ratio of the total amount of compound 132 and compound 134 to compound 133 is It is preferable that the weight ratio of The weight ratio of compound 133 to the total amount of compound 4 is preferably 0.001 or more and 0.05 or less. and more preferably, the range is 0.001 or more and 0.01 or less.

[0111] Also, T G It is preferable that the wavelength is 2.0 eV or less. By adopting this configuration, the light emission with good reliability can be achieved. The element can be obtained.

[0112] <Energy transfer mechanism> Here, we will explain the factors that govern the energy transfer process between molecules. The mechanisms of electron transfer are the Förster mechanism (dipole-dipole interaction) and the Dexter mechanism. Two mechanisms have been proposed: the first excited state (electron exchange interaction) and the second excited state (electron exchange interaction). Regarding the transfer of excitation energy from a material to a second material in the ground state, The energy transfer process between the molecules of the material in 2 is explained. The same is true in the case of

[0113] <Förster mechanism> In the Förster mechanism, the energy transfer does not require direct contact between molecules. Energy transfer occurs through the resonance phenomenon of the dipole vibration of a material and a second material. The first material transfers energy to the second material through the resonance phenomenon of the excitation current, and the first material The first material is in the ground state, and the second material in the ground state is in the excited state. The rate constant of the mechanism, k h*→g is shown in Equation (1).

[0114]

number

[0115] In formula (1), ν represents the frequency, and f' h (ν) is the normalized value of the first material The emission spectrum (or the fluorescence spectrum when discussing energy transfer from a singlet excited state) , and phosphorescence spectrum when discussing energy transfer from triplet excited states), and ε g ( ν) represents the molar extinction coefficient of the second material, N represents Avogadro's number, and n represents the refractive index of the medium. represents the refractive index, R represents the intermolecular distance between the first and second materials, and τ represents the measured excitation represents the lifetime of the state (fluorescence lifetime or phosphorescence lifetime), c represents the speed of light, and φ represents the luminescence quantum yield ( When discussing energy transfer from a singlet excited state, the fluorescence quantum yield is used. When discussing energy transfer from a triplet excited state, the fluorescence quantum yield is used. When discussing energy transfer, it stands for phosphorescence quantum yield, and K 2 is the first material and the second material is a coefficient (0 to 4) that represents the orientation of the transition dipole moment of the The match is K 2 =2 / 3.

[0116] <Dexter System> In the Dexter mechanism, the first and second materials overlap at a certain contact distance. Through the exchange of electrons from the first material in an excited state with those from the second material in the ground state, Energy transfer occurs. The rate constant for the Dexter mechanism is k h*→g is shown in formula (2). vinegar.

[0117]

number

[0118] In formula (2), h is the Planck constant, and K is a constant with the dimension of energy. where ν is the frequency and f' is the h (ν) is the normalized emission spectrum of the first material (When discussing energy transfer from a singlet excited state, the fluorescence spectrum and the triplet excited state are used.) When discussing energy transfer from the nucleophilic state, it represents the phosphorescence spectrum, and ε' g(ν) is the second represents the normalized absorption spectrum of the material, L represents the effective molecular radius, and R represents the first It represents the intermolecular distance between a material and a second material.

[0119] Here, the energy transfer efficiency from the first material to the second material, φ ET is expressed as formula (3). It will be done. r We discuss the emission process of the first material (energy transfer from the singlet excited state). The rate constants are expressed as follows: fluorescence in the case of a compound that is a triplet excited state, and phosphorescence in the case of a compound that is a triplet excited state. S, k n represents the rate constant of the non-radiative process (thermal deactivation and intersystem crossing) of the first material, and τ is the actual represents the lifetime of the excited state of the first material that is measured.

[0120]

number

[0121] From equation (3), the energy transfer efficiency φ ET To increase the rate of energy transfer, Degree constant k h*→g By increasing the other competing rate constants k r +k n (=1 / τ) is relatively It turns out that the smaller it is, the better.

[0122] <Concept for improving energy transfer> First, consider the energy transfer via the Förster mechanism. Substituting equation (1) into equation (3), Therefore, in the case of the Förster mechanism, the energy Energy transfer efficiency φ ET does not depend on the lifetime τ of the excited state of the first material. Movement efficiency φ ET is the emission quantum yield φ (when considering energy transfer from a singlet excited state) is the fluorescence quantum yield, and when discussing energy transfer from the triplet excited state, is the phosphorescence quantum yield) It can be said that higher is better.

[0123] In addition, the emission spectrum of the first material (when discussing energy transfer from a singlet excited state) When discussing energy transfer from triplet excited states, we use the fluorescence spectrum. the absorption spectrum of the first material (corresponding to the transition from the singlet ground state to the singlet excited state) It is preferable that the molar absorption coefficient of the second material is high. This means that the emission spectrum of the first material is preferably the longest wavelength of the second material. This means that the absorption band that appears on the side of the singlet ground state of the second material overlaps with that of the Since direct transition from the triplet excited state to the triplet excited state is forbidden, The molar extinction coefficient for the state is negligible. The energy transfer process from the excited state of the first material to the triplet excited state of the second material is ignored. Therefore, only the energy transfer process to the singlet excited state of the second material needs to be considered.

[0124] Next, consider the energy transfer via the Dexter mechanism. According to equation (2), the rate constant is k h*→g To increase the emission spectrum of the first material (energy from the singlet excited state), When discussing energy transfer, consider the fluorescence spectrum, and when discussing energy transfer from triplet excited states. in the case of phosphorescence spectrum) and the absorption spectrum of the second material (singlet ground state to singlet excited state) It can be seen that it is better to have a larger overlap with the absorption corresponding to the transition to the The efficiency of energy transfer is optimized by matching the emission spectrum of the first material with the longest wavelength of the second material. This is achieved by overlapping with the absorption band appearing on the long side.

[0125] In addition, by substituting formula (2) into formula (3), the energy transfer in the Dexter mechanism is Efficiency φ ET It can be seen that depends on τ. The Dexter mechanism is an energy mechanism based on electron exchange. Since this is a quantum transfer process, the singlet excited state of the first material is converted to the singlet excited state of the second material. Similarly, the energy transfer from the triplet excited state of the first material to the triplet excited state of the second material Energy transfer to the state also occurs.

[0126] Similar to the energy transfer from the first material to the second material, the fluorescent compound is generated from the exciplex. The energy transfer process to the compound is also possible via both the Förster mechanism and the Dexter mechanism. Energy transfer occurs via the mechanism:

[0127] In the light-emitting element of one embodiment of the present invention, the second material is a fluorescent compound. It is preferred that the efficiency of energy transfer to the triplet excited state of the material is low. It is preferred that the efficiency of energy transfer from the material to the second material based on the Dexter mechanism is low. The efficiency of energy transfer from the first material to the second material based on the Förster mechanism is high. It is preferable.

[0128] As already mentioned, the efficiency of energy transfer in the Förster mechanism is On the other hand, the efficiency of energy transfer in the Dexter mechanism does not depend on the lifetime τ of the excited state of the material. depends on the excitation lifetime τ of the first material and reduces the efficiency of energy transfer in the Dexter mechanism. In order to reduce the excitation wavelength, it is preferable that the excitation lifetime τ of the first material is short.

[0129] In view of this, one embodiment of the present invention uses an exciplex or a TADF material as a first material, One of the compounds that forms the exciplex has the function of converting triplet excitation energy into luminescence. According to the configuration of one aspect of the present invention, the triplet excited state of the exciplex (first material) is converted to a singlet excited state. Promotes reverse intersystem crossing to the excited state, and increases the excited state lifetime of the triplet excited state of the exciplex (first material) It is possible to shorten τ. In addition, the triplet excited state of the exciplex (first material) can be converted to a singlet The transition to the ground state is promoted, and the excited lifetime τ of the triplet excited state of the exciplex (first material) is As a result, the triplet excited state of the exciplex (first material) emits fluorescent light. Efficiency of energy transfer to the triplet excited state of a compound (second material) via the Dexter mechanism Therefore, in one embodiment of the present invention, a light-emitting element with high emission efficiency can be provided. It is possible.

[0130] In addition, the fluorescence lifetime of the thermally activated delayed fluorescence component of the emission from the exciplex is short. Specifically, it is preferable that the period is 10 ns or more and 50 μs or less, and more preferably 10 It is preferably from ns to 20 μs, and more preferably from 10 ns to 10 μs.

[0131] The rate constant of the Förster mechanism is inversely proportional to the sixth power of the distance between the first material and the second material. The rate constant of the Dexter mechanism is inversely proportional to the exponential function of the distance between the first and second materials. Therefore, when the distance between the two molecules is approximately 1 nm or less, the Dexter mechanism becomes dominant, and Above 1 nm, the Förster mechanism is dominant. In order to reduce the efficiency of energy transfer, the distance between the first material and the second material is increased. Specifically, it is preferable that the thickness is 0.7 nm or more, and more preferably 0.9 nm or more. m or more, and more preferably 1 nm or more. In addition, the Förster mechanism occurs efficiently. To this end, the distance between the first material and the second material is preferably 5 nm or less.

[0132] Thus, in one embodiment of the present invention, the fluorescent compound, compound 133, is a 2-carbon It is preferable that the compound 133 has at least two of the above alkyl groups. It is preferable that the alkyl group has at least two branched alkyl groups each having 3 to 10 carbon atoms. Alternatively, compound 133 has at least two cyclic hydrocarbon groups having 3 to 10 carbon atoms. or more, or at least two or more bridged cyclic hydrocarbon groups having 3 to 10 carbon atoms. Furthermore, compound 133 has a condensed aromatic hydrocarbon having 3 to 12 carbon atoms. It is preferable to do so.

[0133] <Material> Next, components of a light-emitting element according to one embodiment of the present invention will be described in detail below.

[0134] <Light-emitting layer> The materials that can be used for the light-emitting layer 130 are described below.

[0135] Compound 132 has a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton. The organic compound has good electron transport properties and a high T1 level. Therefore, it can be suitably used as a host material for the light-emitting layer.

[0136] The above-mentioned benzofuropyrimidine skeleton or benzothienopyrimidine skeleton is a benzofuro[3, 2-d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton. Furthermore, the benzofuro[3,2-d]pyrimidine skeleton or the benzothieno[3,2-d]pyrimidine skeleton It is more preferable that the pyrimidine skeleton has a substituent at the 4-position and / or the 8-position. Thus, a light-emitting element with high luminous efficiency and high reliability can be obtained.

[0137] In addition, the compound having the above-mentioned benzofuropyrimidine skeleton or benzothienopyrimidine skeleton is Examples of the compounds include organic compounds having a naphthofuropyrimidinyl group or a naphthothienopyrimidinyl group. Examples of organic compounds having a naphthofuropyrimidinyl group or a naphthothienopyrimidinyl group include The compound has good reliability and can be suitably used in the light-emitting element according to one embodiment of the present invention. do.

[0138] Examples of the benzofuropyrimidine skeleton or benzothienopyrimidine skeleton include Examples of the skeletons are those represented by the following general formulas (101) to (114). X in 01) to (114) represents an oxygen atom or a sulfur atom, and Ht 1 and Ht 2 Haso each independently represents hydrogen or any one of (Ht-1) to (Ht-13) described below; Ar 1 and Ar 2 are each independently hydrogen or any of (Ar-1) to (Ar-27) described below. In the present invention, the benzofuropyrimidinone group is preferably used as a benzofuropyrimidinone group. The organic compounds having a benzothienopyrimidine skeleton or a benzothienopyrimidine skeleton are not limited to the following examples. .

[0139] [ka]

[0140] In addition, the benzofuro[3,2-d]pyrimidine skeleton or benzothieno[3,2-d]pyrimidine skeleton The substituents bonded to the 4-position and / or 8-position of the lysine skeleton are represented by the general formula (101) to A substituent having a π-electron-rich heteroaromatic skeleton, represented by Ht in (114), is preferred. As the skeleton, the furan skeleton, the thiophene skeleton, and the pyrrole skeleton are stable and have good reliability. More preferably, the carbazole skeleton, the dibenzofuran skeleton, the dibenzothiophene skeleton, By using such a structure, a light-emitting element with excellent reliability can be obtained. can.

[0141] The above-mentioned π-electron-rich heteroaromatic skeleton includes, for example, the following general formulas (Ht-1) to ( Examples of the skeletons are those represented by the general formulas (Ht-1) to (Ht-13). In the formula, X represents an oxygen atom or a sulfur atom.

[0142] [ka]

[0143] The above general formulae (101) to (114) and general formulae (Ht-1) to (Ht-13) are The substituent may be an alkyl group having 1 to 6 carbon atoms, a carbon atom, or a substituted group. a cycloalkyl group having 3 to 6 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 6 to 12 carbon atoms; An unsubstituted aryl group can also be selected as a substituent. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples of the alkyl group include butyl, isobutyl, tert-butyl, and n-hexyl groups. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include: Examples include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include phenyl. Specific examples of the substituted aryl group include a phenyl group, a naphthyl group, and a biphenyl group. The groups may be linked together to form a ring. Examples of such rings include fluorene rings. When the 9-position carbon atom in a cyclic ring has two phenyl groups as substituents, the phenyl groups In one example, a spirofluorene skeleton is formed by bonding with In addition, when the compound is unsubstituted, it is advantageous in terms of ease of synthesis and the cost of the raw materials.

[0144] In addition, in the general formulas (101) to (114), Ar 1 and Ar 2 The substituent represented by the formula: Each independently represents a hydrogen atom or a substituted or unsubstituted aryl group having 6 to 25 carbon atoms. Examples of the aryl group having 6 to 25 carbon atoms include a phenyl group, a naphthyl group, and a biphenyl group. More specifically, the alkyl group represented by the following structural formula (Ar Examples of the groups represented by Ar are represented by the formulas (Ar-28) to (Ar-46). 1 and Ar 2 Represented by The possible substituents are not limited to these.

[0145] [ka]

[0146] In addition, the general formulae (Ht-2), (Ht-5), (Ht-8) and (Ht-11) to (Ht In the formula (13), Ar represents a single bond or an arylene group having 6 to 25 carbon atoms; The aryl group may have substituents, and the substituents may be bonded to each other to form a ring. An example of such a compound is a fluorenyl group having a phenyl group as a substituent at the 9-position carbon atom. The two phenyl groups are bonded together to form a spirofluorene skeleton. Examples of the arylene group having 6 to 25 carbon atoms include phenylene group, naphthalenediyl group, biphenyldiyl group, fluorenediyl group, etc. In addition, when the arylene group has a substituent, the substituent can be Examples of the substituent include an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, and the like. An alkyl group or an aryl group having 6 to 12 carbon atoms can also be selected as a substituent. Specific examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and an ethyl group. group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, n- hexyl group, etc. Also, cycloalkyl groups having 3 to 6 carbon atoms can be given as examples. Specific examples of the aryl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, Cyclohexyl groups and the like can also be mentioned. In addition, aryl groups having 6 to 12 carbon atoms can also be mentioned. Specific examples of the group include a phenyl group, a naphthyl group, and a biphenyl group. It is possible.

[0147] The arylene group represented by Ar is, for example, the following structural formula (Ar-1) to (Ar- 27) can be used. The groups that can be used as Ar are Not limited to these.

[0148] [ka]

[0149] In addition, in the general formulas (Ht-3), (Ht-6) and (Ht-9), R 1 is hydrogen, carbon number 1 an alkyl group having 3 to 6 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a cycloalkyl group having 6 carbon atoms A substituted or unsubstituted aryl group having 1 to 13 carbon atoms. Specific examples of the alkyl group having six carbon atoms include a methyl group, an ethyl group, a propyl group, and an isopropyl group. Examples include propyl, butyl, isobutyl, tert-butyl, and n-hexyl groups. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include: For example, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc. Examples of the aryl group having 6 to 13 carbon atoms include Specific examples include a phenyl group, a naphthyl group, a biphenyl group, and a fluorenyl group. Furthermore, the above-mentioned aryl group and phenyl group may have a substituent. The substituents may be bonded to each other to form a ring. The substituents may have 1 to 10 carbon atoms. an alkyl group having 3 to 6 carbon atoms, a cycloalkyl group having 6 to 6 carbon atoms, or An aryl group having 1 to 6 carbon atoms can also be selected as a substituent. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, Examples of the alkyl group include a butyl group, an isobutyl group, a tert-butyl group, and an n-hexyl group. Specific examples of the cycloalkyl group having 3 to 6 carbon atoms include cycloalkyl groups such as Examples of the cyclopropyl group, the cyclobutyl group, the cyclopentyl group, the cyclohexyl group, etc. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, Specific examples include a naphthyl group and a biphenyl group.

[0150] Also, R 1 The alkyl group or aryl group represented by the following structural formula (R-1) is, for example, The groups represented by the following formulas (R-31) to (R-32) can be used. The groups that can be used as the alkyl group are not limited to these.

[0151] [ka]

[0152] In addition, the general formulae (101) to (114), (Ht-1) to (Ht-13), and and Ar, R 1 The substituents that can be possessed by the above structural formulae (R-1) to (R- 32) can be used. The groups that can be used as the group or aryl group are not limited to these.

[0153] As mentioned above, compound 131 can convert triplet excitation energy into luminescence. The organic compound having such a function is preferably a phosphorescent material or a thermally activated type delayed fluorescent material.

[0154] The phosphorescent compound may be an organometallic complex of iridium, rhodium, or platinum, or In addition, platinum complexes with porphyrin ligands and organic iridium complexes complexes, among which organic iridium complexes such as iridium orthometal complexes are mentioned. The orthometalating ligand is preferably a 4H-triazole ligand, a 1H-triazole ligand, or a 2H-triazole ligand. Azole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands In this case, compound 131 (phosphorescent compound) is triplet MLCT (Metal to Ligand Charge Tran) sfer) transition absorption band.

[0155] Examples of substances having a blue or green emission peak include tris{2-[5-(2 -methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazo 3-yl-κN 2 ]phenyl-κC}iridium(III) (abbreviation: Ir(mpp tz-dmp)3), tris(5-methyl-3,4-diphenyl-4H-1,2,4-tris( riazolate)iridium(III) (abbreviation: Ir(Mptz)3), tris[4-(3- Biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]i Iridium(III) (abbreviation: Ir(iPrptz-3b)3), tris[3-(5-biphenyl] (phenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]irid Ir(III) (abbreviation: Ir(iPr5btz)3), a 4H-triazole skeleton and organometallic iridium complexes having tris[3-methyl-1-(2-methylphenyl) -5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir (Mptz1-mp)3), tris(1-methyl-5-phenyl-3-propyl-1H- 1,2,4-Triazolate)iridium(III) (abbreviation: Ir(Prptz1-Me) 3) and fac-triazole-based organometallic iridium complexes. S[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole] Iridium(III) (abbreviation: Ir(iPrpmi)3), tris[3-(2,6-dimethyl phenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(I II) Imidazole skeleton-containing compounds such as Ir(dmpimpt-Me)3 Organic metal iridium complexes and bis[2-(4',6'-difluorophenyl)pyridinato N,C 2’ ]Iridium(III) tetrakis(1-pyrazolyl)borate (abbreviation: FI r6), Bis[2-(4',6'-difluorophenyl)pyridinato-N,C 2’ ]Ili Dium(III) picolinate (abbreviation: FIrpic), bis{2-[3',5'-bis (Trifluoromethyl)phenyl]pyridinato-N,C 2’}Iridium(III) pico Ir(CF3ppy)2(pic) (fluorophenyl)pyridinato-N,C 2’ ]Iridium(III) acetylacetonate (abbreviation: FIr(acac)) Among the above, 4H-triazole is an organometallic iridium complex. Nitrogen-containing five-membered heterocyclic skeletons such as 1H-triazole skeleton and imidazole skeleton The organometallic iridium complex has high triplet excitation energy and is highly reliable and has excellent luminescence efficiency. It is particularly preferred because it is also excellent in

[0156] In addition, examples of substances having a green or yellow emission peak include tris(4-methylphenyl) Ir(mppm)3, Tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: I r(tBuppm)3), (acetylacetonato)bis(6-methyl-4-phenylpyridine Iridium(III) (abbreviation: Ir(mppm)2(acac)), (acetylacetonate ruacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium( III) (abbreviation: Ir(tBuppm)2(acac)), (acetylacetonato)bis [4-(2-norbornyl)-6-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-dimethyl 2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN 3 ]Phenyl- {κC}iridium(III) (abbreviation: Ir(dmppm-dmp)2(acac)), ( Acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)( Abbreviation: Ir(dppm)2(acac) (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazine) Iridium(III) (abbreviation: Ir(mppr-Me)2(acac)), (acetylacetonate arylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinate)irid Pyrazine skeleton such as Ir(III) (abbreviation: Ir(mppr-iPr)2(acac)) Organometallic iridium complexes and tris(2-phenylpyridinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(ppy)3), bis(2-phenylpyridinato-N ,C 2’) Iridium(III) acetylacetonate (abbreviation: Ir(ppy)2(ac ac)), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: Ir(bzq)2(acac)), tris(benzo[h]quinolinato)iridium Ir(III) (abbreviation: Ir(bzq)3), tris(2-phenylquinolinato-N,C 2 ’ ) Iridium(III) (abbreviation: Ir(pq)3), bis(2-phenylquinolinato- N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(pq)2(ac Organometallic iridium complexes with pyridine skeletons such as bis(2,4-difluorophenyl) and Venyl-1,3-oxazolato-N,C 2’ ) Iridium(III) acetylacetoner Ir(dpo)2(acac)), bis{2-[4'-(perfluorophenyl (phenyl)pyridinato-N,C 2’}Iridium(III) acetylacetonate ( Abbreviation: Ir(p-PF-ph)2(acac)), bis(2-phenylbenzothiazol -N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(bt)2(a In addition to organometallic iridium complexes such as tris(acetylacetonato)(monophenyl) Anthroline) terbium(III) (abbreviation: Tb(acac)3(Phen)) Among the above, the organometallic iridium complexes having a pyrimidine skeleton are Dium complexes are particularly preferred because they are remarkably excellent in reliability and luminous efficiency.

[0157] Examples of substances having a yellow or red emission peak include diisobutyryl Methanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(II I) (abbreviation: Ir(5mdppm)2(dibm)), bis[4,6-bis(3-methyl Phenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: Ir (5mdppm)2(dpm)), bis[4,6-di(naphthalene-1-yl)pyrimidinyl] Nato](dipivaloylmethanato)iridium(III) (abbreviation: Ir(d1npm)2( Organometallic iridium complexes with pyrimidine skeletons such as (acetylacetamide) Iridium(III) r(tppr)2(acac)), bis(2,3,5-triphenylpyrazine)(dipyridine) Valoylmethanato)iridium(III) (abbreviation: Ir(tppr)2(dpm)), ( Acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]i Ir(Fdpq)2(acac) and other pyrazine-based compounds Organometallic iridium complexes and tris(1-phenylisoquinolinato-N,C 2’ ) Iridium(III) (abbreviation: Ir(piq)3), bis(1-phenylisoquinolinato -N,C 2’ ) Iridium(III) acetylacetonate (abbreviation: Ir(piq)2( In addition to organometallic iridium complexes with pyridine skeletons such as acac), 2,3,7, 8,12,13,17,18-Octaethyl-21H,23H-porphyrin platinum(II) ) (abbreviation: PtOEP) and tris(1,3-diphenyl-1,3-propanediol). (Eu(DB))(monophenanthroline)europium(III) M) 3(Phen)), tris[1-(2-thenoyl)-3,3,3-trifluoroacetate [Tonato](monophenanthroline)europium(III) (abbreviation: Eu(TTA)3( Among the above, rare earth metal complexes such as pyrimidine skeletons are Organometallic iridium complexes having the above structure are particularly preferred because they are extremely reliable and have excellent luminous efficiency. In addition, organometallic iridium complexes with pyrazine skeletons can emit red light with good chromaticity. can be done.

[0158] In addition, as described above, the material that can be used as compound 131 is a thermally activated Examples of the delayed fluorescent material include the following materials:

[0159] First, fullerene and its derivatives, acridine derivatives such as proflavine, and eosin are listed. In addition, magnesium (Mg), zinc (Zn), cadmium (Cd), tin (S n), platinum (Pt), indium (In), or palladium (Pd) Examples of the metal-containing porphyrin include protoporphyrin. Porphyrin-tin fluoride complex (SnF2(Proto IX)), mesoporphyrin-fluoride Tin complex (SnF2(Meso IX)), hematoporphyrin-tin fluoride complex (Sn F2 (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride Complex (SnF2(Copro III-4Me)), Octaethylporphyrin-fluoride Tin complex (SnF2(OEP)), etioporphyrin-tin fluoride complex (SnF2(E tio I)), octaethylporphyrin-platinum chloride complex (PtCl2OEP), etc. Can be obtained.

[0160] In addition, as a thermally activated delayed fluorescent material composed of one kind of material, π-electron-rich heteroaromatic Heterocyclic compounds having an aromatic ring and a π-electron deficient heteroaromatic ring can also be used. is 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3- a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol PC CzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4, 6-Diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5- Phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl 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]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10'H-spiro[acridine -9,9'-anthracene]-10'-one (abbreviation: ACRSA), etc. Since the heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, Among them, a skeleton having a π-electron-deficient heteroaromatic ring is preferable because it has high transport properties and hole transport properties. Among them, diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or triazine skeleton The azine skeleton is preferred because it is stable and reliable. Among the skeletons that have this structure, the acridine skeleton, the phenoxazine skeleton, the thiophene skeleton, and the furan skeleton are Since the pyrrole skeleton and the pyrrole skeleton are stable and reliable, any one of these skeletons can be used. It is preferable that the pyrrole skeleton has one or more of the following: skeleton, carbazole skeleton, and 3-(9-phenyl-9H-carbazol-3-yl)- In addition, a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are particularly preferable. The substance in which the heteroaromatic ring is directly bonded to the π-electron-rich heteroaromatic ring exhibits the donor property of the π-electron-deficient heteroaromatic ring. The acceptor properties of the heteroaromatic rings are both strong, and the energy levels of the singlet excited state and triplet excited state are This is particularly preferred since the difference between the energy level of the excited state and the energy level of the excited state is small.

[0161] In addition, the compound 133 in the light-emitting layer 130 is preferably a fluorescent compound. The compound is not particularly limited, but may be an anthracene derivative, a tetracene derivative, or a chrysene derivative. Derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, Cridone derivatives, coumarin derivatives, phenoxazine derivatives, phenoxazine derivatives, Thiazine derivatives and the like are preferred.

[0162] Specifically, 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2 ,2'-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4'-(10-phenyl -9-anthryl)biphenyl-4-yl]-2,2'-bipyridine (abbreviation: PAPP2 BPy), N,N'-diphenyl-N,N'-bis[4-(9-phenyl-9H-fluoro 1,6-Pyrene-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn) , N,N'-bis(3-methylphenyl)-N,N'-bis[3-(9-phenyl-9H -fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMem FLPAPrn), N,N'-bis[4-(9-phenyl-9H-fluoren-9-yl )phenyl]-N,N'-bis(4-tert-butylphenyl)pyrene-1,6-diazo 1,6tBu-FLPAPrn, N,N'-bis[4-(9-phenyl- 9H-Fluoren-9-yl)phenyl]-N,N'-diphenyl-3,8-dicyclohexyl Xylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N,N'-biphenyl S[4-(9H-carbazol-9-yl)phenyl]-N,N'-diphenylstilbe YGA2S, 4-(9H-carbazol-9-yl) -4'-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA) , 4-(9H-carbazol-9-yl)-4'-(9,10-diphenyl-2-anthracene N,9-diphenyl-N-[4- (10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation Name: PCAPA), Perylene, 2,5,8,11-tetra(tert-butyl)perylene (abbreviation: TBP), 4-(10-phenyl-9-anthryl)-4'-(9-phenyl- 9H-Carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), N,N' '-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene) Bis[N,N',N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPAB PA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl] phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9 ,10-diphenyl-2-anthryl)phenyl]-N,N',N'-triphenyl-1 ,4-Phenylenediamine (abbreviation: 2DPAPPA), N,N,N',N',N'',N '',N''',N'''-Octaphenyldibenzo[g,p]chrysene-2,7,10 ,15-Tetraamine (abbreviation: DBC1), Coumarin 30, N-(9,10-diphenyl -2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2 PCAPA), N-[9,10-bis(1,1'-biphenyl-2-yl)-2-anthracene aryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPh A), N-(9,10-diphenyl-2-anthryl)-N,N',N'-triphenyl -1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(1,1 '-biphenyl-2-yl)-2-anthryl]-N,N',N'-triphenyl-1, 4-Phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(1,1'-biphenyl) phenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N- Phenylanthracene-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenyl Dianthracene-9-amine (abbreviation: DPhAPhA), Coumarin 6, Coumarin 545T , N,N'-diphenylquinacridone (abbreviation: DPQd), rubrene, 2,8-di-te rt-Butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyl Tetrathracene (abbreviation: TBRb), Nile Red, 5,12-bis(1,1'-biphenyl) 2-(2-(2-phenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), [4-(Dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-yl 2-(2-methyl-6-[2-(2,3-dimethylphenyl)propanedinitrile (abbreviation: DCM1), ,6,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl ]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N ',N'-Tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N',N'-tetrakis(4-methyl phenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p -mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl 2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl )Ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI) , 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3, 6,7-Tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl)ethenyl] -4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2, 6-Bis{2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-yl 2-{2,6-bis[2-(8- Methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H -benzo[ij]quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene}p Dopanedinitrile (abbreviation: BisDCJTM), 5,10,15,20-tetraphenyl Bisbenzo[5,6]indeno[1,2,3-cd:1',2',3'-lm]perylene , etc.

[0163] In addition, when compound 131 and compound 132 form an exciplex, the exciplex formed is The emission peak of the compound 133, which is the luminescent material, is at the longest wavelength (lowest energy) absorption peak. It is preferable to select compounds 131, 132, and 133 so that they overlap with the band. This makes it possible to provide a light emitting device with significantly improved luminous efficiency.

[0164] The light-emitting layer 130 may be formed of two or more layers. When the light-emitting layer 130 is formed by laminating the first light-emitting layer and the second light-emitting layer in this order from the hole transport layer side, A substance having a hole transporting property is used as a host material for the first light-emitting layer, and a substance having a hole transporting property is used as a host material for the second light-emitting layer. For example, a substance having an electron transport property is used as the insulating film.

[0165] As shown in FIG. 4, in the light-emitting layer 130, the compound 131, the compound 132, and The compound 132 may contain a material other than the compound 133 (compound 134). It is preferable to form an exciplex with compound 134. The HOMO level of one of the compounds 134 is the highest among the materials in the light-emitting layer 130. The other LUMO level is the lowest LUMO level of the material in the light-emitting layer 130. That is, it is preferable that the HOMO level of one of the compounds 132 and 134 is The HOMO level of the other compound is higher than that of compound 131, and the LUMO level of the other compound is higher than that of compound 132. It is preferred that the LUMO level of the compound is lower than the LUMO level of the other compound and the LUMO level of compound 131. This structure suppresses the reaction of compound 132 and compound 131 to form an exciplex. It is possible.

[0166] As the compound 134, for example, the following hole transport material and electron transport material can be used: However, as mentioned above, compound 132 has a benzofuropyrimidine backbone or a benzothieno Because it has a pyrimidine skeleton, it has a low LUMO level and good electron transport properties. Therefore, compound 134 has a higher HOMO level than compound 132 and has good hole transport properties. An organic compound (hole transporting material) is preferred.

[0167] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used. ×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The hole transporting material may be an aromatic amine, a carbazole derivative, or the like. The material may be a polymer.

[0168] As examples of materials with high hole transport properties, aromatic amine compounds include N,N' -Di(p-tolyl)-N,N'-diphenyl-p-phenylenediamine (abbreviation: DTDP PA), 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'-di Amine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl Examples include]-N-phenylamino]benzene (abbreviation: DPA3B).

[0169] Specific examples of carbazole derivatives include 3-[N-(4-diphenylamino phenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1 ), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9 -Phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenyl [N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation :PCzTPN2), 3-[N-(9-phenylcarbazol-3-yl)-N-phenyl 3,6-bis[N- (9-Phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazol PCzPCA2, 3-[N-(1-naphthyl)-N-(9-phenylcarbazone] carbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1) etc. can be mentioned.

[0170] Another example of a carbazole derivative is 4,4'-di(N-carbazolyl)biphene. Nyl (abbreviation: CBP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzoyl Zene (abbreviation: TCPB), 1,4-bis[4-(N-carbazolyl)phenyl]-2,3 , 5,6-tetraphenylbenzene, etc. can be used.

[0171] As a material with high hole transport properties, for example, 4,4'-bis[N-(1-naphthyl )-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD) and N,N'-biphenyl S(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4 '-Diamine (abbreviation: TPD), 4,4',4''-tris(carbazol-9-yl) Triphenylamine (abbreviation: TCTA), 4,4',4''-tris[N-(1-naphthalene 1'-TNATA, 4,4'-N-phenylamino]triphenylamine ,4''-Tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA ), 4,4',4''-tris[N-(3-methylphenyl)-N-phenylamino] Triphenylamine (abbreviation: m-MTDATA), 4,4'-bis[N-(spiro-9,9 '-Bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-Phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (abbreviation :BPAFLP), 4-phenyl-3'-(9-phenylfluoren-9-yl)trifluoroacetate mBPAFLP, N-(9,9-dimethyl-9H-fluorene- 2-yl)-N-{9,9-dimethyl-2-[N'-phenyl-N'-(9,9-dimethyl (amino)-9H-fluoren-7-yl}phenyl DFLADFL, N-(9,9-dimethyl-2-diphenylamino-9H -fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-difluorophenyl) (N-phenylaminophenyl)-N-phenylamino]spiro-9,9'-bifluorene (abbreviation :DPASF), 4-phenyl-4'-(9-phenyl-9H-carbazol-3-yl ) Triphenylamine (abbreviation: PCBA1BP), 4,4'-diphenyl-4''-(9 -phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1 BP), 4-(1-naphthyl)-4'-(9-phenyl-9H-carbazol-3-yl ) Triphenylamine (abbreviation: PCBANB), 4,4'-di(1-naphthyl)-4'' -(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCB NBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl) Amine (abbreviation: PCA1BP), N,N'-bis(9-phenylcarbazol-3-yl) )-N,N'-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N' ,N''-Triphenyl-N,N',N''-tris(9-phenylcarbazole-3- N-(4-biphenylyl)benzene-1,3,5-triamine (abbreviation: PCA3B) )-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazone PCBiF, N-(1,1'-biphenyl-4-yl) )-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9- Dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl- N-Phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl] Fluorene-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl 9,9'-bifluorene-2-yl-9H-carbazol-3-ylphenyl Amine (abbreviation: PCBASF), 2-[N-(9-phenylcarbazol-3-yl)- N-phenylamino]spiro-9,9'-bifluorene (abbreviation: PCASF), 2,7- Bis[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9' -Bifluorene (abbreviation: DPA2SF), N-[4-(9H-carbazol-9-yl) Phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N' -Bis[4-(carbazol-9-yl)phenyl]-N,N'-diphenyl-9,9- Aromatic amine compounds such as dimethylfluorene-2,7-diamine (abbreviation: YGA2F) Also, 3-[4-(1-naphthyl)-phenyl]-9-phenyl can be used. PCPN, 3-[4-(9-phenanthryl)-phenyl nyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3,3'-bis(9 -phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis(N-carbazolidine) mCP, 3,6-bis(3,5-diphenylphenyl)-9-phenyl CzTP, 4-{3-[3-(9-phenyl-9H-fluoro oren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi- II), 4,4',4''-(benzene-1,3,5-triyl)tri(dibenzofuran) ) (abbreviation: DBF3P-II), 1,3,5-tri(dibenzothiophen-4-yl)benzyl DBT3P-II, 2,8-diphenyl-4-[4-(9-phenyl- 9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-I II), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-fluor (abbreviation: DBTFLP-IV), 4-[3-(triphenylene -2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II) and other amines compounds, carbazole compounds, thiophene compounds, furan compounds, fluorene compounds, The materials mentioned herein include phenylene compounds, phenanthrene compounds, etc. is mainly 1×10 -6 cm 2 A material that has a hole mobility of at least / Vs. Substances other than these may be used as long as they have a higher hole transporting property than the above.

[0172] The electrode 101 and the electrode 102 have a function of injecting holes and electrons into the light-emitting layer 130. The electrodes 101 and 102 are made of metals, alloys, conductive compounds, and mixtures or laminates thereof. The metal can be aluminum (Al) as a typical example. , and other transition metals such as silver (Ag), tungsten, chromium, molybdenum, copper, and titanium. , alkali metals such as lithium (Li) and cesium, calcium, magnesium (Mg) Group 2 metals such as ytterbium (Yb) can be used as transition metals. A rare earth metal may be used. As the alloy, an alloy containing the above metals may be used. Examples of the conductive compound include MgAg and AlLi. Indium tin oxide (ITO), silicon or silicon oxide Including indium tin oxide (abbreviation: ITSO), indium zinc oxide (Indium Z inc Oxide), tungsten and zinc-containing indium oxide, etc. As the conductive compound, an inorganic carbon-based material such as graphene may be used. As described above, electrodes 101 and 10 are formed by stacking multiple layers of these materials. 2 or both may be formed.

[0173] The light emitted from the light-emitting layer 130 is emitted from one or both of the electrodes 101 and 102. Therefore, at least one of the electrodes 101 and 102 is visible. The conductive material has a function of transmitting light. The transmittance is 40% or more and 100% or less, preferably 60% or more and 100% or less, and the resistance Resistance is 1×10 -2 Materials with a conductivity of Ω cm or less are also suitable. The electrode is made of a conductive material having a function of transmitting light and a function of reflecting light. The conductive material has a visible light reflectance of 20% or more and 80% or less, preferably 4 0% to 70% and its resistivity is 1×10 -2 Conductive materials with a resistance of Ω·cm or less When a material with low optical transparency, such as a metal or alloy, is used for the electrode that extracts light, The electrode 10 is formed with a thickness that is thick enough to transmit visible light (for example, 1 nm to 10 nm). Either or both of the electrode 101 and the electrode 102 may be formed.

[0174] In this specification and the like, the electrode having a function of transmitting light includes an electrode having a function of transmitting visible light. Any material having both the function and electrical conductivity may be used, and examples thereof include ITO as mentioned above. In addition to the oxide conductor layer, an oxide semiconductor layer or an organic conductor layer containing an organic material is included. The organic conductive layer containing an organic substance may be, for example, a layer containing an organic compound and an electron donor. A layer including a composite material obtained by mixing an organic compound and an electron acceptor. The resistivity of the transparent conductive layer is preferably 1×10 5 Ω cm or less, more preferably 1×10 4 Ω·cm or less.

[0175] The electrode 101 and the electrode 102 may be formed by a sputtering method, a vapor deposition method, a printing method, or the like. Coating method, MBE (Molecular Beam Epitaxy) method, CVD (Chemical Vapor Deposition) method Phase Growth, Pulsed Laser Deposition, ALD (Atomic Layer Deposit) The ion method and the like can be appropriately used.

[0176] <Hole injection layer> The hole injection layer 111 is configured to inject holes from one of the pair of electrodes (electrode 101 or electrode 102). It has the function of promoting hole injection by reducing the injection barrier. It is formed by phthalocyanine derivatives or aromatic amines. Transition metal oxides and Examples include molybdenum oxide, vanadium oxide, ruthenium oxide, and tungsten oxide. , manganese oxide, etc. Phthalocyanine derivatives include phthalocyanine, Examples of aromatic amines include benzidine derivatives and phenyl Diamine derivatives, etc. Polymer compounds such as polythiophene and polyaniline It is also possible to use self-doped polythiophenes, such as poly(ethylenediamine). Representative examples include poly(oxythiophene) / poly(styrenesulfonic acid).

[0177] The hole injection layer 111 is made of a compound of a hole transporting material and a material that has an electron accepting property. Alternatively, a layer containing a material exhibiting electron accepting properties and a layer containing a positive electrode may be used. A stack of layers containing hole transporting materials may also be used. It is possible to give and receive electric charges in the presence of a magnetic field. Materials that exhibit electron-accepting properties include quinodimethane. Organic acceptors such as aryl, chloranil, and hexaazatriphenylene derivatives Specifically, 7,7,8,8-tetracyano-2,3,5,6- Tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, 2,3,6,7, 10,11-Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation These are compounds that have electron-withdrawing groups (halogen groups or cyano groups) such as aryloxycarbonyl (HAT-CN). In addition, transition metal oxides, for example oxides of metals in Groups 4 to 8, can be used. In particular, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, and oxide These include tungsten oxide, manganese oxide, and rhenium oxide. Among these, molybdenum oxide is Among these, it is preferred because it is stable, has low hygroscopicity, and is easy to handle.

[0178] As the hole transporting material, a material having a higher hole transporting property than an electron transporting property can be used. ×10 -6 cm 2 It is preferable that the material has a hole mobility of 1 / Vs or more. The aromatic amines and the like listed as hole transporting materials that can be used in the light emitting layer 130 are Carbazole derivatives can be used. Aromatic hydrocarbons and stilbene derivatives can also be used. The hole transporting material may be a polymer compound.

[0179] Examples of aromatic hydrocarbons include 2-tert-butyl-9,10-di(2-naphthyl) 2-tert-butyl-9,10-di(1 -naphthyl)anthracene, 9,10-bis(3,5-diphenylphenyl)anthracene DPPA, 2-tert-butyl-9,10-bis(4-phenylphenyl) )anthracene (abbreviation: t-BuDBA), 9,10-di(2-naphthyl)anthracene (Abbreviation: DNA), 9,10-diphenylanthracene (Abbreviation: DPAnth), 2-t ert-Butylanthracene (abbreviation: t-BuAnth), 9,10-bis(4-methyl -1-naphthyl)anthracene (abbreviation: DMNA), 2-tert-butyl-9,10- Bis[2-(1-naphthyl)phenyl]anthracene, 9,10-bis[2-(1-naphthyl)phenyl]anthracene 2,3,6,7-tetramethyl-9,10-di(1-nathyl)phenyl]anthracene 2,3,6,7-tetramethyl-9,10-di(2-naphthyl)anthracene Anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl tolyl, 10,10'-bis(2-phenylphenyl)-9,9'-bianthryl, 10 ,10'-Bis[(2,3,4,5,6-pentaphenyl)phenyl]-9,9'-bis Anthracene, anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra (tert-butyl)perylene, etc. In addition, pentacene, coronene, etc. can also be used. Thus, 1×10 -6 cm 2 / Vs or more It is more preferable to use aromatic hydrocarbons having 14 or more carbon atoms and 42 or less carbon atoms.

[0180] The aromatic hydrocarbon may have a vinyl skeleton. Examples of aromatic hydrocarbons include 4,4'-bis(2,2-diphenylvinyl)biphenyl. (abbreviation: DPVBi), 9,10-bis[4-(2,2-diphenylvinyl)phenyl] anthracene (abbreviation: DPVPA), etc.

[0181] In addition, poly(N-vinylcarbazole) (abbreviation: PVK) and poly(4-vinyltriphenylphosphine) 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 Polymer compounds such as Poly(phenyl)benzidine (abbreviation: Poly-TPD) can also be used. can.

[0182] <Hole transport layer> The hole transport layer 112 is a layer containing a hole transporting material. The hole transport layer 112 is formed by injecting the hole into the hole injection layer 111. Since it has a function of transporting holes to the light-emitting layer 130, it has a HOMO level similar to that of the hole injection layer 111. It is preferable that the HOMO level of each of the aryl groups is the same as or close to the HOMO level of each of the aryl groups.

[0183] As the hole transport material, the material exemplified as the material of the hole injection layer 111 is used. Also, 1×10 -6 cm 2 The material has a hole mobility of ≥ 100 / Vs. However, other materials may be used as long as they have a higher hole transporting property than an electron transporting property. The layer containing a substance having a high hole transporting property may be a single layer or a layer containing the above-mentioned substance. Two or more layers may be laminated.

[0184] ≪Electron transport layer≫ The electron transport layer 118 is connected to the other of the pair of electrodes (electrode 101 or The material has a function of transporting electrons injected from the electrode 102 to the light-emitting layer 130. A material with a higher electron transport capacity than holes can be used as the -6 cm 2 It is preferable that the material has an electron mobility of 100 / Vs or more. As materials with electron transport properties, π-electron-deficient compounds such as nitrogen-containing heteroaromatic compounds are Heteroaromatics and metal complexes can be used. In particular, benzofuropyrimidine structures or is preferably an organic compound having a benzothienopyrimidine skeleton. is a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand. Metal complexes having ligands are also available. Conductors, phenanthroline derivatives, pyridine derivatives, bipyridine derivatives, pyrimidine derivatives In addition, other substances that have a higher electron transporting property than a hole transporting property can be used. The electron transport layer 118 may be a single layer or a multilayer structure. Two or more layers of the above substances may be laminated.

[0185] A specific example of the electron transport material is tris(8-quinolinolato)aluminum (III ) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium ( II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenyl) (Enolato)aluminum(III)(abbreviation: BAlq), bis(8-quinolinolato)zinc (II) (abbreviation: Znq), etc., metal complexes having a quinoline or benzoquinoline skeleton In addition, bis[2-(2-benzoxazolyl)phenolato]zinc(I I) (abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc (I I) Metal complexes with oxazole and thiazole ligands such as ZnBTZ In addition to metal complexes, 2-(4-biphenylyl)-5 -(4-tert-Butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD) and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazo OXD-7), 9-[4-(5-phenyl-1,3, 4-Oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11) , 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)- 1,2,4-Triazole (abbreviation: TAZ), 2,2',2''-(1,3,5-benzene (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzo Imidazole (abbreviation: mDBTBIm-II), bathophenanthroline (abbreviation: BPhe n), Bathocuproine (abbreviation: BCP), 2,9-bis(naphthalene-2-yl)-4 ,7-Diphenyl-1,10-phenanthroline (abbreviation: NBPhen) and other heterocyclization Compounds such as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]ky Noxalin (abbreviation: 2mDBTPDBq-II), 2-[3'-(dibenzothiophene- 4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBT BPDBq-II), 2-[3'-(9H-carbazol-9-yl)biphenyl-3- yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3 ,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quino Xaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophene-4-yl) 7mDBTPDBq-II 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxalate 6mDBTPDBq-II, 4,6-bis[3-(phenanthrene-9-yl) 4,6-bis[3-(4-phenyl)pyrimidine (abbreviation: 4,6mPnP2Pm), Dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4 ,6-Bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4, Heterocyclic compounds with diazine skeletons such as 2-{4-[3-(N -phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl {phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn) Heterocyclic compounds with triazine skeletons and 3,5-bis[3-(9H-carbazole-9 -yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3 -pyridyl)phenyl]benzene (abbreviation: TmPyPB) The heterocyclic compound, 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene ( Heteroaromatic compounds such as poly(2,5- pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7- diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), poly[(9, 9-Dioctylfluorene-2,7-diyl)-co-(2,2'-bipyridine-6,6 Polymer compounds such as PF-BPy (abbreviation: PF-BPy) can also be used. The substances mentioned here are mainly 1×10 -6 cm 2 / Vs or higher. Note that any substance other than those mentioned above may be used as long as it has a higher electron transporting property than a hole transporting property. In addition, organic compounds having a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton are A mixture thereof can be suitably used.

[0186] In addition, a layer for controlling the movement of electron carriers is provided between the electron transport layer 118 and the light emitting layer 130. The layer for controlling the movement of electron carriers may be made of a material having high electron transport properties as described above. A small amount of a substance with high electron trapping properties is added to the layer, which suppresses the movement of electron carriers. This makes it possible to adjust the carrier balance. To prevent problems caused by electrons penetrating through layers (such as reduced device life) It has a great effect.

[0187] ≪Electron injection layer≫ The electron injection layer 119 promotes electron injection by reducing the electron injection barrier from the electrode 102. For example, Group 1 metals, Group 2 metals, or their oxides and halides In addition, the above-mentioned electron transporting material and the corresponding electron A composite material of a material exhibiting electron donating properties can also be used. Examples of the metal include Group 1 metals, Group 2 metals, and oxides thereof. Lithium fluoride (LiF), sodium fluoride (NaF), and cesium fluoride (CsF ), calcium fluoride (CaF2), lithium oxide (LiO x ) and other alkaline gold Metals, alkaline earth metals, or compounds thereof can be used. A rare earth metal compound such as fluorine (ErF3) can be used. An electride may be used for 119. The electride may be, for example, calcium. Examples include a material in which electrons are highly concentrated in a mixed oxide of aluminum and ruthenium. The injection layer 119 may be made of a material that can be used in the electron transport layer 118 .

[0188] In addition, the electron injection layer 119 is made of a composite material obtained by mixing an organic compound and an electron donor. Such composite materials may be made by adding electrons to an organic compound via an electron donor. In this case, the organic compound is It is preferable that the material has excellent transport properties for the generated electrons. Specifically, for example, the above-mentioned The material constituting the electron transport layer 118 (metal complex, heteroaromatic compound, etc.) can be used. The electron donor may be any substance that exhibits electron donating properties to organic compounds. For the metal, alkali metals, alkaline earth metals and rare earth metals are preferred, and lithium, cesium, Magnesium, calcium, erbium, ytterbium, etc. Preferred are lithium metal oxides and alkaline earth metal oxides, and lithium oxide and calcium oxide are preferred. , barium oxide, etc. Also, Lewis bases such as magnesium oxide are used. It is also possible to use organic compounds such as tetrathiafulvalene (TTF). It is also possible.

[0189] The above-mentioned light-emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer are These are deposition method (including vacuum deposition method), inkjet method, coating method, and nozzle printing method, respectively. The light-emitting layer and the hole-injection layer can be formed by a method such as gravure printing. In addition to the above-mentioned materials, the hole transport layer, the electron transport layer, and the electron injection layer may be made of quantum dots or the like. Inorganic compounds or polymeric compounds (oligomers, dendrimers, polymers, etc.) may be used. stomach.

[0190] The quantum dots are classified into colloidal quantum dots, alloy quantum dots, and core-shell quantum dots. In addition, a group 2 and a group 16, a group 13 and a group 14, and a core type quantum dot may be used. Contains element groups 15, 13 and 17, 11 and 17, or 14 and 15 Quantum dots may also be used. Alternatively, cadmium (Cd), selenium (Se), zinc (Zn ), sulfur (S), phosphorus (P), indium (In), tellurium (Te), lead (Pb), gallium (Ga), Quantum dots containing elements such as Ga, Arsenic, and Aluminum are used. It's fine.

[0191] Examples of liquid media used in wet processes include methyl ethyl ketone, cyclohexane, etc. Ketones such as xanone, fatty acid esters such as ethyl acetate, halogens such as dichlorobenzene Hydrocarbons, aromatics such as toluene, xylene, mesitylene, and cyclohexylbenzene Hydrocarbons, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, dimethylformamide, etc. Organic solvents such as dichloromethane (DMF) and dimethyl sulfoxide (DMSO) can be used. Cut.

[0192] Examples of polymer compounds that can be used in the light-emitting layer include poly[2-methoxy]phenylene. [MeH] -PPV), polyphenylenes such as poly(2,5-dioctyl-1,4-phenylenevinylene), Poly(9,9-di-n-octylfluorenyl-2,7 -diyl) (abbreviation: PF8), poly[(9,9-di-n-octylfluorenyl-2,7 -diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)](abbreviation Name: F8BT), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)- alt-(2,2'-bithiophene-5,5'-diyl)] (abbreviated as F8T2), poly[( 9,9-Dioctyl-2,7-Divinylenefluorenylene)-alt-(9,10-An thracene)], poly[(9,9-dihexylfluorene-2,7-diyl)-alt-( Polyfluorene derivatives such as poly(3-hexyl) Polyalkylthiophenes (P) such as silthiophene-2,5-diyl (abbreviation: P3HT) AT) derivatives, polyphenylene derivatives, etc. PVK, poly(2-vinylnaphthalene), poly[bis(4-phenyl)(2,4,6-tetramethylphenyl) A luminescent compound is added to a polymer compound such as PTAA. The light-emitting compound may be doped and used in the light-emitting layer. can be used.

[0193] In one embodiment of the present invention, a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton is an organic compound having a triplet excitation energy, an organic compound capable of converting triplet excitation energy into luminescence, and a fluorescent compound having a Three types of organic compounds that emit light are mixed and used in the light-emitting layer 130. For example, a polymer compound having a benzofuropyrimidine skeleton or The compound has a benzothienopyrimidine skeleton and a substituent that can convert triplet excitation energy into luminescence. A polymer compound having a substituent that exhibits fluorescent light may be used as the light-emitting layer 130. In addition, the benzofuropyrimidine skeleton or the benzothienopyrimidine skeleton and the triplet excited state A polymer compound having a substituent capable of converting energy into light emission and a low molecular weight compound exhibiting fluorescent light emission. The light-emitting layer 130 may be fabricated by mixing the polymer compound. This can improve the efficiency of material utilization and reduce the manufacturing cost.

[0194] <Substrate> In addition, the light-emitting element according to one embodiment of the present invention is provided on a substrate made of glass, plastic, or the like. Regarding the order of fabrication on the substrate, the layers may be stacked in order from the electrode 101 side. They may be laminated in order from the pole 102 side.

[0195] The substrate on which the light-emitting element according to one embodiment of the present invention can be formed is, for example, glass or quartz. A flexible substrate may be used. The substrate is a flexible substrate, such as polycarbonate. Examples of the substrate include plastic substrates made of polyacrylate and polyarylate. In the process of manufacturing the light-emitting element, a film formed by vapor deposition may be used. Any other material may be used as long as it functions as a light-emitting element. Anything that has a function will suffice.

[0196] For example, in the present invention, a light emitting element can be formed using various substrates. The type of the substrate is not particularly limited. An example of the substrate is a semiconductor substrate (e.g., a single crystal substrate or silicon substrate), SOI substrate, glass substrate, quartz substrate, plastic substrate, metal Substrate, stainless steel substrate, substrate with stainless steel foil, tungsten substrate, substrate with tungsten foil, flexible substrate, laminated film, fibrous These include cellulose nanofibers (CNF), paper, and base films that contain the above materials. Examples of glass substrates include barium borosilicate glass, aluminoborosilicate glass, or Soda lime glass, etc. Flexible substrates, laminated films, base films, etc. Examples include polyethylene terephthalate (PET), poly Polyethylene naphthalate (PEN), polyethersulfone (PES), polytetrafluoroethylene Examples of plastics include PTFE (polytetrafluoroethylene). Resins such as acrylic resins are also available. Examples include polypropylene, polyester, and polypropylene. Examples include polyvinyl fluoride, polyvinyl chloride, etc., or polyamide, Examples include polyimide, aramid, epoxy, inorganic vapor deposition film, and paper.

[0197] In addition, a flexible substrate may be used as the substrate, and the light emitting element may be formed directly on the flexible substrate. Alternatively, a release layer may be provided between the substrate and the light-emitting element. After a part or all of a chip is completed, it is separated from the board and used to transfer it to another board. In this case, the light-emitting element can be transferred onto a substrate having poor heat resistance or a flexible substrate. The above-mentioned peeling layer has a laminated structure of inorganic films, for example, a tungsten film and a silicon oxide film. or a structure in which a resin film such as polyimide is formed on a substrate.

[0198] That is, a light emitting element is formed using a certain substrate, and then the light emitting element is transferred to another substrate. The light emitting element may be disposed on another substrate. In addition to the above mentioned substrates, cellophane substrates, stone substrates, wood substrates, fabric substrates (natural fibers (silk, cotton, Hemp), synthetic fibers (nylon, polyurethane, polyester) or regenerated fibers (acetate (including cellulose, cupra, rayon, recycled polyester, etc.), leather substrate, rubber substrate, etc. By using these substrates, light-emitting elements that are not easily broken and have high heat resistance can be produced. The light emitting element may be a small light emitting element, a light emitting element that is lighter in weight, or a light emitting element that is thinner.

[0199] Also, for example, a field effect transistor (FET) is formed on the above-mentioned substrate, and the FET and The light emitting element 150 may be fabricated on the electrically connected electrodes. In this way, an active matrix display device that controls the driving of light emitting elements can be manufactured.

[0200] The structure shown in this embodiment mode can be used in appropriate combination with other embodiment modes. Cut.

[0201] (Embodiment 2) In this embodiment mode, a light-emitting element having a different structure from that of the light-emitting element shown in Embodiment 1 is used. The following will be described with reference to FIG. 5. In FIG. 5, the reference numerals shown in FIG. Parts having the same function may be indicated with the same hatch pattern and the reference numerals may be omitted. In addition, parts having similar functions are denoted by similar reference numerals, and detailed descriptions thereof may be omitted. There is a match.

[0202] <Light-emitting element configuration example 2> FIG. 5 is a schematic cross-sectional view of the light-emitting element 250. As shown in FIG.

[0203] The light-emitting element 250 shown in FIG. 5 has a plurality of electrodes between a pair of electrodes (electrodes 101 and 102). The light-emitting unit 106 and the light-emitting unit 108 are light-emitting units. Any one of the light-emitting units of the knit is the same as the EL layer 100 shown in FIG. In other words, the light emitting element 150 shown in FIG. It is preferable that the light emitting element 250 has a plurality of light emitting units. In the optical element 250, the electrode 101 functions as an anode and the electrode 102 functions as a cathode. However, the following description will be given assuming that the light emitting element 250 has the opposite configuration.

[0204] In addition, in the light-emitting element 250 shown in FIG. The light-emitting unit 106 and the light-emitting unit 108 are laminated together, and a charge generating layer 1 is provided between the light-emitting unit 106 and the light-emitting unit 108. The light-emitting units 106 and 108 have different configurations. For example, the light-emitting unit 108 may have the same structure as the EL layer 100. This is preferable.

[0205] The light emitting element 250 includes a light emitting layer 120 and a light emitting layer 170. In addition to the light-emitting layer 120, the knit 106 includes a hole injection layer 111, a hole transport layer 112, an electron transport The light-emitting unit 108 also includes an emissive layer 170. In addition to the above, a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 11 Has 9.

[0206] The light-emitting element 250 is provided in any of the layers of the light-emitting unit 106 and the light-emitting unit 108. It is sufficient that the organic compound according to one embodiment of the present invention is contained. The electron transport layer 113 or the electron transport layer 118 is preferable as the light emitting layer. The optical layer 120 or the light-emitting layer 170 .

[0207] The charge generating layer 115 is formed by adding an acceptor material, which is an electron acceptor, to a hole transporting material. Even if the structure is such that the electron transport material is a material having a donor property, the structure may be such that the donor property is added to the electron transport material. In addition, both of these configurations may be laminated.

[0208] When the charge generating layer 115 contains a composite material of an organic compound and an acceptor substance, As the composite material, the composite material which can be used for the hole-injection layer 111 shown in Embodiment 1 is used. The organic compounds include aromatic amine compounds, carbazole compounds, aromatic carbon compounds, etc. Various compounds such as hydrogen and polymer compounds (oligomers, dendrimers, polymers, etc.) are used. As an organic compound, a hole mobility of 1×10 -6 cm 2 / Vs However, it is preferable to use a material having a higher hole transporting property than an electron transporting property. Other materials may be used as long as they are compatible with the organic compound and the acceptor material. The material has excellent carrier injection and transport properties, enabling low-voltage and low-current operation. In addition, the anode side surface of the light-emitting unit is in contact with the charge generating layer 115. In this case, the charge generating layer 115 also serves as a hole injection layer or a hole transport layer for the light emitting unit. Therefore, the light-emitting unit does not need to have a hole injection layer or a hole transport layer. Alternatively, when the cathode side surface of the light-emitting unit is in contact with the charge generating layer 115, The charge generating layer 115 also serves as an electron injection layer or an electron transport layer for the light emitting unit. Therefore, the light-emitting unit does not have an electron injection layer or an electron transport layer. is also good.

[0209] The charge generating layer 115 may be a layer including a composite material of an organic compound and an acceptor substance. For example, the organic EL element may be formed as a laminated structure in which layers made of the organic material are combined. A layer including a composite material of a compound and an acceptor material, and a layer including a compound selected from an electron donor material. The compound may be combined with a compound having a high electron transporting property to form a layer. A layer including a composite material of an organic compound and an acceptor substance and a layer including a transparent conductive film are combined. It may be formed by combining the above.

[0210] The charge generating layer 115 sandwiched between the light emitting unit 106 and the light emitting unit 108 is When a voltage is applied between the electrode 101 and the electrode 102, electrons are injected into one of the light-emitting units, It is sufficient if the electrode 1 injects holes into the other light-emitting unit. When a voltage is applied so that the potential of electrode 01 is higher than the potential of electrode 102, a charge is generated. Layer 115 injects electrons into light-emitting unit 106 and holes into light-emitting unit 108. .

[0211] From the viewpoint of light extraction efficiency, the charge generating layer 115 is required to be transparent to visible light (specifically, It is preferable that the charge generating layer 115 has a visible light transmittance of 40% or more. In addition, the charge generating layer 115 has a lower electrical conductivity than the pair of electrodes (the electrodes 101 and 102). But it still works.

[0212] When the charge generating layer 115 is formed using the above-mentioned material, the light emitting layer is laminated. In this case, the increase in the driving voltage can be suppressed.

[0213] In addition, in FIG. 5, a light emitting element having two light emitting units has been described. The same can be applied to a light-emitting element in which two or more light-emitting units are stacked. As shown in the light-emitting element 250, a plurality of light-emitting units are separated by a charge generating layer between a pair of electrodes. By arranging the LEDs in this way, it is possible to achieve high brightness light emission while keeping the current density low, and also to achieve a long life. In addition, a light-emitting element with low power consumption can be realized.

[0214] In each of the above configurations, the light emitting units 106 and 108 are The light emitting colors of the light emitting materials may be the same or different. The guest unit 106 and the light-emitting unit 108 have the same color light emission properties. When the material is included, the light-emitting element 250 becomes a light-emitting element that exhibits high light emission luminance with a small current value. It is more preferable that the light emitting units 106 and 108 emit light of different colors. When the light-emitting device 250 includes a guest material capable of emitting light, the light-emitting device 250 emits multicolor light. In this case, either one of the light-emitting layer 120 and the light-emitting layer 170 or In both cases, the light emitting element 250 is formed by using a plurality of light emitting materials having different emission wavelengths. The emission spectrum is a composite of light with different emission peaks, so Both of these result in emission spectra with two maxima.

[0215] The above-mentioned structure is also suitable for obtaining white light emission. By making the lights complementary to each other, white light can be obtained. The design is such that the resulting white light has a high light emission, or at least light emission having red, green and blue colors. It is preferable to select a material that is

[0216] The light-emitting layer 130 shown in the first embodiment may be used for one or both of the light-emitting layer 120 and the light-emitting layer 170. By using this configuration, it is possible to obtain light emitting devices with good light emitting efficiency and reliability. The guest material contained in the light-emitting layer 130 is a fluorescent material. Therefore, the light-emitting layer 120 and / or the light-emitting layer 170 may be formed using the light-emitting layer shown in the first embodiment. By using the configuration of 130, a light-emitting element with a sharp emission spectrum and high color purity can be obtained. It is possible.

[0217] In addition, in the case of a light-emitting element having three or more stacked light-emitting units, the The emission colors of the guest materials may be the same or different. In the case where a plurality of light-emitting units that emit light are included, the emission colors of the plurality of light-emitting units are as follows: Compared to other colors, it is possible to obtain high luminance with a small current value. The composition can be suitably used to adjust the luminous color. This is suitable when using a guest material that exhibits a luminescent color. For example, In this case, two layers of light-emitting units having fluorescent materials of the same color are used, and one layer of a light-emitting material having a different color from the fluorescent material is used. By forming a light-emitting unit having a phosphorescent material that exhibits fluorescence and phosphorescence in a single layer, the intensity of the fluorescence and phosphorescence can be enhanced. In other words, the light emission intensity of each color can be adjusted by changing the number of light-emitting units. It is possible.

[0218] In the case of a light-emitting device having two layers of such fluorescent light-emitting units and one layer of a phosphorescent light-emitting unit, The light-emitting layer includes two layers of light-emitting units containing color fluorescent materials and one layer of light-emitting unit containing yellow phosphorescent materials. The light-emitting element has two layers of light-emitting units including a blue fluorescent material, and a red phosphorescent material and a green phosphorescent material. A light-emitting element having one layer of a light-emitting unit containing a blue fluorescent material or two layers of light-emitting units containing a blue fluorescent material. and a light-emitting element having one layer of a light-emitting unit including a red phosphorescent material, a yellow phosphorescent material, and a green phosphorescent material. This is preferable because white light can be efficiently emitted.

[0219] In addition, at least one of the light-emitting layer 120 and the light-emitting layer 170 is further divided into layers, Each of the divided layers may contain a different light-emitting material. Alternatively, at least one of the light-emitting layers 170 may be composed of two or more layers. For example, the first light-emitting layer and the second light-emitting layer can be laminated in this order from the hole transport layer side to form the light-emitting layer. In this case, a material having a hole transporting property is used as the host material of the first light-emitting layer, and a material having a hole transporting property is used as the host material of the second light-emitting layer. In this case, a material having an electron transporting property is used as the host material. The light-emitting material in the light-emitting layer and the second light-emitting layer may be the same or different. Even if a material has a function of emitting light of the same color, it is preferable that the material has a function of emitting light of different colors. The material may be a material having the following function: By using a material with a structure that has three primary colors or four or more colors, it is possible to obtain white light with high color rendering. It is also possible.

[0220] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0221] (Embodiment 3) In this embodiment, a light-emitting device using the light-emitting element described in Embodiments 1 and 2 is This will be described with reference to FIG. 6(A) and FIG. 6(B).

[0222] FIG. 6(A) is a top view showing a light-emitting device, and FIG. 6(B) is a cross-sectional view of FIG. 6(A) along lines AB and CD. This light emitting device is a cross-sectional view of a light emitting element. The illustrated driving circuit section (source side driving circuit) 601, pixel section 602, and driving circuit section (gate side The driver circuit 603 is a sealing substrate 604, a desiccant 625, and a shielding material 605. The inside surrounded by the sealing material 605 is a space 607 .

[0223] The lead wiring 608 is connected to the source side driver circuit 601 and the gate side driver circuit 603. The wiring is for transmitting the signals to be input, and the FPC (flexible printed circuit board) is the external input terminal. Video signal, clock signal, start signal, reset signal, etc. from the 609 Although only the FPC is shown here, the FPC has a printed wiring board. Even if a printed wiring board (PWB) is installed, The light emitting device in this specification includes not only the light emitting device itself but also an FPC or This includes the state where the PWB is installed.

[0224] Next, a cross-sectional structure of the light emitting device will be described with reference to FIG. A driving circuit section and a pixel section are formed on the source side driving circuit section. A circuit 601 and one pixel in a pixel portion 602 are shown.

[0225] The source side driver circuit 601 includes an n-channel TFT 623 and a p-channel TFT 624. The driver circuit is a combination of various CMOS circuits, It may be formed of a MOS circuit or an NMOS circuit. This shows a driver integrated type with a driver circuit formed on the board, but this is not necessarily required. Alternatively, it may be formed externally.

[0226] The pixel section 602 includes a switching TFT 611, a current control TFT 612 and its drain. The pixel includes a first electrode 613 electrically connected to the input. An insulator 614 is formed so as to cover the end of the electrode 613. The insulating layer can be formed by using a photosensitive resin film having a mold.

[0227] In order to improve the coverage of the film formed on the insulator 614, the insulator 614 is The upper end or the lower end is formed to have a curved surface. For example, When photosensitive acrylic is used as the material, it is possible to make only the upper end of the insulator 614 curved. The radius of curvature of the curved surface is preferably 0.2 μm or more and 0.3 μm or less. The border 614 may be either a negative or positive photosensitive material.

[0228] An EL layer 616 and a second electrode 617 are formed on the first electrode 613. Here, the material used for the first electrode 613 functioning as an anode is a material having a work function of It is desirable to use a material with a large capacitance. For example, an ITO film or an indium tin oxide film containing silicon. Indium tin oxide film, indium oxide film containing 2wt% to 20wt% zinc oxide, nitride In addition to single-layer films such as titanium film, chromium film, tungsten film, Zn film, and Pt film, titanium nitride film and Lamination with a film mainly composed of aluminum, titanium nitride film and a film mainly composed of aluminum A three-layer structure of a titanium nitride film and a silicon nitride film can be used. The resistance of the anode is low, good ohmic contact can be achieved, and the anode can function as well. This can be done.

[0229] The EL layer 616 is formed by deposition using a deposition mask, inkjet printing, or spin coating. The EL layer 616 can be formed by various methods such as the above. The polymer may be a polymer compound (including an oligomer or a dendrimer).

[0230] Furthermore, a material for a second electrode 617 formed on the EL layer 616 and functioning as a cathode As the material, materials with a small work function (Al, Mg, Li, Ca, or alloys or compounds of these) It is preferable to use a material such as MgAg, MgIn, or AlLi. In the case where the generated light is transmitted through the second electrode 617, a thin film is used as the second electrode 617. A thin metal film and a transparent conductive film (ITO, containing 2wt% to 20wt% zinc oxide) Indium oxide, silicon-containing indium tin oxide, zinc oxide (ZnO, etc.) It is better to use layers.

[0231] The first electrode 613, the EL layer 616, and the second electrode 617 form a light-emitting element 618. The light emitting element 618 is a light emitting element having the configurations of the first and second embodiments. It is preferable that the pixel portion is formed with a plurality of light emitting elements. In the light emitting device of the embodiment, a light emitting device having the configuration described in the first and second embodiments is The light-emitting element may include both a light-emitting element and a light-emitting element having other configurations.

[0232] Furthermore, the sealing substrate 604 is bonded to the element substrate 610 with a sealant 605, A light emitting element is disposed in a space 607 surrounded by a child substrate 610, a sealing substrate 604, and a sealant 605. 618. The space 607 is filled with a filler. In addition to inert gas (nitrogen, argon, etc.) being filled, resin, desiccant or its Sometimes it is filled with both.

[0233] It is preferable to use epoxy resin or glass frit for the sealing material 605. It is desirable that these materials are as impermeable to moisture and oxygen as possible. Materials used for the sealing substrate 604 include glass substrates, quartz substrates, and FRP (Fiber Reinforced Plastics). reinforced plastics), PVF (polyvinyl fluoride), polyester A plastic substrate made of, for example, polyester or acrylic can be used.

[0234] As described above, a light emitting device using the light emitting elements described in the first and second embodiments can be obtained.

[0235] <Light-emitting device configuration example 1> FIG. 7 shows an example of a display device in which a light-emitting element that emits white light is formed and a colored layer (color filter An example of a light emitting device in which a GaN-GaN filter is formed is shown.

[0236] FIG. 7A shows a substrate 1001, an insulating base film 1002, a gate insulating film 1003, and a gate electrode. 1006, 1007, 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021 , a peripheral portion 1042, a pixel portion 1040, a driving circuit portion 1041, and a first electrode 102 of a light-emitting element. 4W, 1024R, 1024G, 1024B, partition wall 1026, EL layer 1028, light-emitting element The second electrode 1029, the sealing substrate 1031, the sealant 1032, the red pixel 1044R, the green Shown are color pixels 1044G, blue pixels 1044B, white pixels 1044W, etc.

[0237] In addition, in FIG. 7(A), the colored layers (red colored layer 1034R, green colored layer 1034G, blue A colored layer (1034B) is provided on the transparent substrate 1033. A transparent substrate 1 having a colored layer and a black layer may be further provided. The colored layer and the black layer are fixed to the substrate 1001. In FIG. 7(A), the EL layer 1028 is covered with a bar coat layer 1036. The light emitted from the colored layers is divided into two types: light that does not pass through the colored layers and goes out, and light that passes through the colored layers of each color and goes out. The light that does not pass through the colored layer is white, and the light that passes through the colored layer is red, blue, or green. This makes it possible to express images using four color pixels.

[0238] In FIG. 7B, a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 103 An example in which 4B is formed between the gate insulating film 1003 and the first interlayer insulating film 1020 is shown. As shown in FIG. 7B, the colored layer may be provided between the substrate 1001 and the sealing substrate 1031. stomach.

[0239] In the light emitting device described above, the light is taken in toward the substrate 1001 on which the TFT is formed. The light emitting device has a bottom emission structure, but the light is taken in from the sealing substrate 1031 side. The light emitting device may have a top emission structure.

[0240] <Configuration Example 2 of Light Emitting Device> Cross-sectional views of a top-emission type light-emitting device are shown in Figures 8(A) and 8(B). The plate 1001 can be a light-opaque substrate. The process is the same as that of a bottom emission type light emitting device until the connection electrodes are formed. Thereafter, a third interlayer insulating film 1037 is formed to cover the electrode 1022. This insulating film is planarized. The third interlayer insulating film 1037 may have the same function as the second interlayer insulating film 1021. In addition to the above materials, various other materials can be used.

[0241] The lower electrode 1025W, the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1 Here, 025B is an anode, but it may be a cathode. In the case of a top emission type light emitting device such as the above, the lower electrode 1025W, the lower electrode It is preferable that the lower electrode 1025R, the lower electrode 1025G, and the lower electrode 1025B are reflective electrodes. It is preferable that the second electrode 1029 has a function of reflecting light and a function of transmitting light. In addition, the second electrode 1029, the lower electrode 1025W, the lower electrode 1025R, and the lower electrode 1 A microcavity structure is applied between the lower electrode 1025B and the lower electrode 1025G to detect light of a specific wavelength. The EL layer 1028 has a structure similar to that of the first embodiment and the second embodiment. The device has a configuration as described in embodiment 2, and has an element structure capable of obtaining white light emission.

[0242] In FIG. 7(A), FIG. 7(B), FIG. 8(A) and FIG. 8(B), white light is emitted. The L layer may be configured using multiple light-emitting layers or multiple light-emitting units. However, the configuration for obtaining white light emission is not limited to the above.

[0243] In the top emission structure shown in FIG. 8(A) and (B), a colored layer (red colored layer 103 4R, a green colored layer 1034G, and a blue colored layer 1034B) are provided on the sealing substrate 1031. The sealing substrate 1031 is provided with black insulating film 1032 disposed between the pixels. A layer (black matrix) 1030 may be provided. A color layer (red color layer 1034R , green colored layer 1034G, blue colored layer 1034B) and black layer (black matrix The sealing substrate 1031 may be covered with an overcoat layer. A substrate having optical properties is used.

[0244] In addition, in FIG. 8(A), a full-color display using three colors, red, green, and blue, is shown. As shown in B), a full-color display may be performed using four colors: red, green, blue, and white. The full-color display is not limited to the above. For example, a full-color display using four colors, red, green, blue, and yellow, may be used. A full color display may also be performed.

[0245] A light-emitting element according to one embodiment of the present invention uses a fluorescent material as a guest material. Compared to other materials, the spectrum is sharper, so light with high color purity can be obtained. Therefore, by using the light-emitting element in the light-emitting device shown in this embodiment, color reproducibility can be improved. Therefore, a light emitting device with high light emission efficiency can be obtained.

[0246] As described above, a light emitting device using the light emitting elements described in the first and second embodiments can be obtained.

[0247] Note that this embodiment mode can be appropriately combined with other embodiment modes.

[0248] (Embodiment 4) In this embodiment, an electronic device and a display device according to one embodiment of the present invention will be described.

[0249] According to one embodiment of the present invention, a highly reliable electronic device and display having a flat surface and high light emission efficiency can be provided. According to one embodiment of the present invention, a reliable display device having a curved surface and high light emission efficiency can be manufactured. The light-emitting element of one embodiment of the present invention has high color purity. Therefore, when the light-emitting element is used in the light-emitting device described in this embodiment, By this, it is possible to obtain electronic devices and display devices with high color reproducibility.

[0250] Examples of electronic devices include television sets, desktop or notebook PCs, etc. Computers, monitors for computers, digital cameras, digital video cameras Cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, audio playback Examples of such devices include large gaming machines such as pachinko machines.

[0251] A portable information terminal 900 shown in FIGS. 9A and 9B includes a housing 901, a housing 902, a display unit 90 3, and a hinge portion 905.

[0252] The housing 901 and the housing 902 are connected by a hinge portion 905. The mobile information terminal 900 includes: It can be unfolded from the folded state (FIG. 9(A)) to the state shown in FIG. 9(B). This makes it highly portable when you carry it around, and when you use it, the large display area makes it easy to see. Excellent recognition.

[0253] The portable information terminal 900 has a housing 901 and a housing 902 connected by a hinge portion 905. A flexible display unit 903 is provided.

[0254] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 903. This makes it possible to manufacture a highly reliable portable information terminal.

[0255] The display unit 903 is capable of displaying at least one of document information, still images, and moving images. When the display unit 903 displays document information, the portable information terminal 900 can be used as an e-book reader. It can be used as a terminal.

[0256] When the portable information terminal 900 is unfolded, the display portion 903 is held in a largely curved state. For example, the radius of curvature is 1 mm or more and 50 mm or less, preferably 5 mm or more and 30 mm or less. The display unit 903 is supported by the housing 901 and the cover 902. Pixels are continuously arranged from 902 to 902, enabling a curved display.

[0257] The display unit 903 functions as a touch panel and can be operated by a finger, a stylus, etc. can.

[0258] It is preferable that the display unit 903 is composed of one flexible display. This makes it possible to perform continuous display without interruption between the housing 901 and the housing 902. In addition, a display may be provided in each of the housings 901 and 902. You may do so.

[0259] The hinge portion 905 is a portion that connects the housing 901 and the housing 902 when the mobile information terminal 900 is unfolded. It is preferable to have a locking mechanism to prevent the angle from becoming larger than a predetermined angle. For example, the angle at which the door will lock (will not open any further) must be greater than 90 degrees and less than 180 degrees. Typically, the angle is 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 17 degrees. 5 degrees, etc. This improves the convenience, safety, and Reliability can be improved.

[0260] If the hinge portion 905 has a locking mechanism, the display portion 903 can be opened without applying excessive force. Therefore, it is possible to prevent the display unit 903 from being damaged. It can be achieved.

[0261] The housing 901 and the housing 902 are provided with a power button, an operation button, an external connection port, a speaker, a microphone, and the like. It may have an inch or the like.

[0262] A wireless communication module is provided in either the housing 901 or the housing 902. Internet, LAN (Local Area Network), Wi-Fi (registered trademark ) and the like.

[0263] A portable information terminal 910 shown in FIG. 9C includes a housing 911, a display unit 912, and an operation button 913. , an external connection port 914, a speaker 915, a microphone 916, a camera 917, etc.

[0264] A light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 912. This makes it possible to manufacture portable information terminals with a high yield.

[0265] The mobile information terminal 910 has a touch sensor on the display unit 912. All operations, such as inputting characters, can be performed by touching the display 912 with a finger or a stylus. It can be done.

[0266] In addition, the operation button 913 is operated to turn the power on and off, and to display on the display unit 912. For example, you can change the type of image displayed on the main screen from the email composition screen. You can switch to the menu screen.

[0267] In addition, a detection device such as a gyro sensor or an acceleration sensor is provided inside the portable information terminal 910. By providing the above, the orientation of the mobile information terminal 910 (vertical or horizontal) can be determined and the screen of the display unit 912 can be adjusted. The display orientation can be switched automatically. The screen orientation can also be switched by The input is made by touching the display unit 912, by operating the operation button 913, or by inputting voice using the microphone 916. It can also be performed by using force or the like.

[0268] The mobile information terminal 910 is, for example, one or more devices selected from a telephone, a notebook, an information viewing device, etc. Or it has multiple functions. Specifically, it can be used as a smartphone. The information terminal 910 is, for example, a mobile phone, an e-mail, a document viewing and creation, a music playback, a video It can run various applications such as playback, internet communication, and games. do.

[0269] The camera 920 shown in FIG. 9(D) includes a housing 921, a display unit 922, an operation button 923, and a shutter. The camera 920 also has a detachable lens 926. It is attached.

[0270] The light-emitting device manufactured according to one embodiment of the present invention can be used for the display portion 922. This makes it possible to manufacture a highly reliable camera.

[0271] Here, the camera 920 and the lens 926 can be removed from the housing 921 and replaced. However, the lens 926 and the housing 921 may be integrated together.

[0272] The camera 920 captures still or moving images by pressing the shutter button 924. In addition, the display unit 922 has a function as a touch panel. It is also possible to capture an image by touching the

[0273] The camera 920 can be equipped with a strobe device, viewfinder, etc. Alternatively, these may be incorporated into the housing 921.

[0274] FIG. 10A is a schematic diagram showing an example of a cleaning robot.

[0275] The cleaning robot 5100 has a display 5101 arranged on the top surface and multiple The camera 5102, the brush 5103, and the operation button 5104 are also shown. However, the underside of the cleaning robot 5100 is provided with tires, a suction port, etc. The robot 5100 also has an infrared sensor, an ultrasonic sensor, an acceleration sensor, a piezo sensor, It is equipped with various sensors such as a sensor, a light sensor, and a gyro sensor. 100 is equipped with wireless communication means.

[0276] The cleaning robot 5100 moves by itself, detects dirt 5120, and sucks it out from the suction port on its bottom. It can suck up dirt.

[0277] In addition, the cleaning robot 5100 analyzes the image captured by the camera 5102 and detects walls, furniture, or It can detect obstacles such as steps. It can also detect wiring and other obstacles by image analysis. If an object that is likely to get tangled in the brush 5103 is detected, the rotation of the brush 5103 can be stopped. can.

[0278] The display 5101 can display the remaining battery level, the amount of dirt sucked up, etc. The route traveled by the cleaning robot 5100 can be displayed on the display 5101. In addition, the display 5101 may be a touch panel, and the operation buttons 5104 may be a display. It may be provided in the ray 5101.

[0279] The cleaning robot 5100 can communicate with a portable electronic device 5140 such as a smartphone. The images captured by the camera 5102 can be displayed on the portable electronic device 5140. Therefore, the owner of the Cleaning Robot 5100 can check the state of the room even when he / she is away from home. In addition, the display on the display 5101 can be displayed on a mobile electronic device such as a smartphone. You can also check at 5140.

[0280] The light-emitting device according to one embodiment of the present invention can be used for the display 5101 .

[0281] The robot 2100 shown in FIG. 10(B) includes a computing device 2110, an illuminance sensor 2101, A microphone 2102, an upper camera 2103, a speaker 2104, a display 2105, It is equipped with a lower camera 2106, an obstacle sensor 2107, and a movement mechanism 2108.

[0282] The microphone 2102 has a function of detecting the user's voice and environmental sounds. The speaker 2104 has a function of emitting sound. The user can communicate with the computer using the computer 2102 and the speaker 2104. It is possible.

[0283] The display 2105 has a function of displaying various information. It is possible for the user to display desired information on the display 2105. The display 2105 may be equipped with a touch panel. The information terminal may be a terminal that can be used for charging and discharging the battery. and enables data transfer.

[0284] The upper camera 2103 and the lower camera 2106 are used to capture images of the surroundings of the robot 2100. The obstacle sensor 2107 detects the obstacles of the robot 210 using the moving mechanism 2108. When the robot 21 moves forward, it can sense the presence or absence of obstacles in its path. 00 uses an upper camera 2103, a lower camera 2106, and an obstacle sensor 2107. It is possible for the robot to recognize its surrounding environment and move around safely.

[0285] The light-emitting device according to one embodiment of the present invention can be used for the display 2105 .

[0286] FIG. 10C is a diagram showing an example of a goggle-type display. Goggle-type display For example, the device includes a housing 5000, a display unit 5001, a speaker 5003, and an LED lamp 5004. , operation keys 5005 (including a power switch or an operation switch), a connection terminal 5006, Sensor 5007 (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, Temperature, chemicals, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient (including functions for measuring temperature, vibration, smell, or infrared rays), microphone 5008, It has a second display unit 5002, a support unit 5012, earphones 5013, and the like.

[0287] The light-emitting device of one embodiment of the present invention can be used for the display portion 5001 and the second display portion 5002. can.

[0288] 11(A) and (B) show a foldable mobile information terminal 5150. The foldable mobile information terminal 5150 includes a housing 5151, a display area 5152, and a bending portion 515. 11(A) shows the portable information terminal 5150 in an unfolded state. FIG. 5B) shows the portable information terminal 5150 in a folded state. The portable information terminal 5150 is large. Although it has a large display area 5152, it can be folded up to be compact and highly portable.

[0289] The display area 5152 can be folded in half by the bend 5153. 3 is composed of an expandable member and multiple support members, and when folding, the expandable The member is stretched, and the bent portion 5153 has a radius of curvature of 2 mm or more, preferably 5 mm or more. It can be folded.

[0290] The display area 5152 is a touch panel (input / output) equipped with a touch sensor (input device). The light-emitting device according to one embodiment of the present invention can be used in the display region 5152. Cut.

[0291] This embodiment mode can be combined with other embodiment modes as appropriate.

[0292] (Embodiment 5) In this embodiment, an example in which the light-emitting element of one embodiment of the present invention is applied to various lighting devices will be described. The light-emitting element according to one embodiment of the present invention is used to improve the light-emitting efficiency. Thus, a highly reliable lighting device can be manufactured.

[0293] The light-emitting element of one embodiment of the present invention can be fabricated over a flexible substrate to have a curved surface. It is possible to realize electronic devices and lighting devices having a light-emitting region.

[0294] In addition, a light-emitting device using a light-emitting element according to one embodiment of the present invention can be used for automobile lighting. For example, lighting can be installed on the windshield, ceiling, etc.

[0295] FIG. 12 shows an example in which the light-emitting element is used as an indoor lighting device 8501. Since the surface area can be increased, a large-area lighting device can be formed. By using a housing having such a shape, a lighting device 8502 having a curved light-emitting area can be formed. The light-emitting element shown in this embodiment mode has a thin film shape, and the design of the housing has a high degree of freedom. Therefore, it is possible to form lighting devices with various elaborate designs. A large lighting device 8503 may be provided on the wall. A touch sensor may be provided in 503 to turn the power on or off.

[0296] In addition, by using light-emitting elements on the surface of the table, it has the function of a table. The lighting device 8504 can be used as a lighting device. This makes it possible to provide a lighting device that also functions as furniture.

[0297] In this manner, a lighting device and an electronic device can be obtained by using a light-emitting element of one embodiment of the present invention. Note that the lighting devices and electronic devices to which the present invention can be applied are the same as those described in this embodiment. The present invention can be applied to lighting devices and electronic devices in a wide range of fields.

[0298] The structure described in this embodiment may be used in appropriate combination with structures described in other embodiments. There can be. EXAMPLES

[0299] In this example, a manufacturing example of a light-emitting element according to one embodiment of the present invention will be described. The structure of the optical element is the same as that shown in FIG. 1(A). The details of the element structure are shown in Table 1. The structures and abbreviations of the compounds are shown below.

[0300] [ka]

[0301] [Table 1]

[0302] <Fabrication of light-emitting element> A method for manufacturing the light-emitting element manufactured in this embodiment will be described below.

[0303] <Fabrication of light-emitting element 1> An ITSO film was formed on a glass substrate as an electrode 101 to a thickness of 70 nm. The electrode area of ​​the electrode 101 is 4 mm 2 (2mm x 2mm).

[0304] Next, a hole injection layer 111 made of DBT3P-II and molybdenum oxide was formed on the electrode 101. (MoO3) and the weight ratio (DBT3P-II:MoO3) was 1:0.5. The deposition was carried out to a thickness of 30 nm.

[0305] Next, on the hole injection layer 111, 9-[3-(9-phenyl-9 H-fluoren-9-yl)phenyl]-9H-carbazole (abbreviation: mCzFLP) The deposition was carried out to a thickness of 20 nm.

[0306] Next, on the hole transport layer 112, 4-{3-[3'-(9H-carba benzofuro[3,2-d]pyrimidine (abbreviation Name: 4mCzBPBfpm) and tris[3-methyl-1-(2-methylphenyl)-5 -phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: Ir(M PTZ1-MP)3) and N,N'-bis(4-tert-butylphenyl)-N,N' -Bis[4-(dibenzofuran-2-yl)phenyl]-pyrene-1,6-diamine (abbreviation Name: 1,6tBuFrBAPrn) and the weight ratio (4mCzBPBfpm:Ir(Mpt z1-mp) 3:1, 6tBuFrBAPrn) 0.8:0.2:0.01 The luminescent layer 130 was co-evaporated to a thickness of 30 nm. uFrBAPrn is a fluorescent compound and Ir(Mptz1-mp)3 is a phosphorescent compound. be.

[0307] Next, on the light-emitting layer 130, 4mCzBPBfpm was deposited to a thickness of 1 The deposition was performed in sequence so that the thickness of NBPhen was 5 nm and the thickness of NBPhen was 10 nm. On the electron transport layer 118, LiF was deposited to a thickness of 1 nm as the electron injection layer 119. It was evaporated.

[0308] Next, on the electron injection layer 119, aluminum (Al) was deposited to a thickness of 20 It was formed so that the thickness was 0 nm.

[0309] Next, in a glove box with a nitrogen atmosphere, a glass substrate for sealing is The EL sealant is used to fix the organic material to the glass substrate, forming a light-emitting element 1. Specifically, a sealant was applied to the periphery of the organic material formed on the glass substrate, and the The glass substrate and the sealing glass substrate are bonded together, and ultraviolet light with a wavelength of 365 nm is applied for 6 hours. J / cm 2 The light-emitting element 1 was obtained by irradiating the light with light and then heat-treating it for 1 hour at 80° C.

[0310] <Fabrication of light-emitting element 2> The light-emitting element 2 differs from the light-emitting element 1 described above only in the process of forming the light-emitting layer 130. The steps were the same as those for the light-emitting element 1.

[0311] The light-emitting layer 130 of the light-emitting element 2 is made of 4mCzBPBfpm and Ir(Mptz1-mp )3 and 10-acetyl-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl 1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolizine-11- On (abbreviation: coumarin521T) and the weight ratio (4mCzBPBfpm:Ir( Mptz1-mp)3:coumarin521T) was 0.8:0.2:0.005 In the light-emitting layer 130, co umarin521T is the third organic fluorescent compound, Ir(Mptz1 -mp)3 is a phosphorescent compound.

[0312] <Characteristics of light-emitting element> Next, the characteristics of the fabricated light-emitting element 1 and light-emitting element 2 were measured. The intensity was measured using a color luminance meter (Topcon, BM-5A), and the electroluminescence spectrum was measured. A multichannel spectrometer (PMA-11, manufactured by Hamamatsu Photonics) was used for the measurement.

[0313] FIG. 13 shows the current efficiency-luminance characteristics of the light-emitting element 1 and the light-emitting element 2, and FIG. 14 shows the current-voltage characteristics of the light-emitting element 1 and the light-emitting element 2. The external quantum efficiency vs. luminance characteristics of the light-emitting element 1 and the light-emitting element 2 are shown in FIG. 2, 2.5mA / cm 2 The electroluminescence spectrum when a current is applied at a current density of The results are shown in Figure 16. The measurements of each light-emitting element were carried out at room temperature (in an atmosphere maintained at 23°C).

[0314] Also, 1000cd / m 2 The element characteristics of the light-emitting element 1 and the light-emitting element 2 in the vicinity are shown in Table 2. As shown in.

[0315] [Table 2]

[0316] As shown in FIG. 16, the emission spectra of the light-emitting element 1 and the light-emitting element 2 each have a peak wavelength of 4 87 nm, 480 nm, and the fluorescent compound 1,6tBuFrBAPrn, cou The blue luminescence derived from marin521T was observed. The light-emitting element 1 and the light-emitting element 2 have a small full width at half maximum of the electroluminescence spectrum and exhibit high color purity. Therefore, it is suitable for display devices.

[0317] In addition, as shown in FIG. 13, FIG. 15 and Table 2, the light-emitting element 1 and the light-emitting element 2 have high luminous efficiency. The efficiency (current efficiency, power efficiency, and external quantum efficiency) of the photoelectron beam is shown in Fig. 1. The probability of generating singlet excitons by recombination of injected carriers (holes and electrons) is Since the maximum efficiency is 25%, the external quantum efficiency when the light extraction efficiency to the outside is 25% is The external quantum efficiency of the light-emitting element 1 and the light-emitting element 2 is 6. The efficiency is higher than 25%. In Device 2, in addition to the emission from singlet excitons, the phosphorescent compound Ir(Mp By passing through tz1-mp3, triplet excitons are converted into singlet excitons and emit fluorescence. This is because it is possible to make contributions.

[0318] In addition, the light-emitting element 1 and the light-emitting element 2 show a decrease in efficiency on the high luminance side (also called roll-off). As described above, the small roll-off is one of the characteristics of the light-emitting element of one embodiment of the present invention. It is.

[0319] In addition, benzo[4mCzBPBfpm, which is used as the host material for light-emitting devices 1 and 2, Organic compounds with a furopyrimidine skeleton have high S1 and T1 levels. As a result, it is possible to obtain a highly efficient light-emitting element that emits blue fluorescence, such as the light-emitting element 1 and the light-emitting element 2. Cut. EXAMPLES

[0320] In this example, a manufacturing example of a light-emitting element according to one embodiment of the present invention and a comparative light-emitting element will be described. The structure of the light-emitting element manufactured in this example is the same as that shown in Figure 1(A). The details of the element structure are shown in Table 3. The structures and abbreviations of the compounds used are shown below. The structures and abbreviations of other compounds are shown in the actual examples. Please refer to Example 1.

[0321] [ka]

[0322] [Table 3]

[0323] <Fabrication of light-emitting element> A method for manufacturing the light-emitting element manufactured in this embodiment will be described below.

[0324] <Fabrication of light-emitting element 3> An ITSO film was formed on a glass substrate as an electrode 101 to a thickness of 70 nm. The electrode area of ​​the electrode 101 is 4 mm 2 (2mm x 2mm).

[0325] Next, a hole injection layer 111 made of DBT3P-II and molybdenum oxide was formed on the electrode 101. (MoO3) and the weight ratio (DBT3P-II:MoO3) was 1:0.5. The deposition was carried out to a thickness of 40 nm.

[0326] Next, on the hole injection layer 111, 9-[3-(9-phenyl-9 H-fluoren-9-yl)phenyl]-9H-carbazole (abbreviation: mCzFLP) The deposition was carried out to a thickness of 20 nm.

[0327] Next, on the hole transport layer 112, a light emitting layer 130 was formed by depositing 4mCzBPBfpm and tris[ 2-(1H-pyrazol-1-yl-κN 2 )phenyl-κC]iridium(III)( Abbreviation: Ir(ppz)3) and 10-(2-benzothiazolyl)-2,3,6,7-tetrahydrofuran Hydro-1,1,7,7-tetramethyl-1H,5H,11H-[1]benzopyrano[ 6,7,8-ij]quinolizin-11-one (abbreviation: coumarin545T) and The weight ratio (4mCzBPBfpm:Ir(ppz)3:coumarin545T) is 0. The mixture was co-evaporated to a thickness of 30 nm with a ratio of 8:0.2:0.005. In the optical layer 130, coumarin545T is the fluorescent compound.

[0328] Next, on the light-emitting layer 130, 4mCzBPBfpm was deposited to a thickness of 1 The deposition was performed in sequence so that the thickness of the ZnO film was 5 nm, and the thickness of the NBPhen film was 20 nm. On the electron transport layer 118, LiF was deposited to a thickness of 1 nm as the electron injection layer 119. It was evaporated.

[0329] Next, on the electron injection layer 119, aluminum (Al) was deposited to a thickness of 20 It was formed so that the thickness was 0 nm.

[0330] Next, in a glove box with a nitrogen atmosphere, a glass substrate for sealing is The EL sealant is used to fix the organic material to the glass substrate, forming a light-emitting element 3. Specifically, a sealant was applied to the periphery of the organic material formed on the glass substrate, and the The glass substrate and the sealing glass substrate are bonded together, and ultraviolet light with a wavelength of 365 nm is applied for 6 hours. J / cm 2The light-emitting element 3 was obtained by irradiating the light with light and then heat-treating it for 1 hour at 80° C.

[0331] <Preparation of comparative light-emitting element 4> The comparative light-emitting element 4 is different from the light-emitting element 3 described above only in the process of forming the light-emitting layer 130. The other steps were the same as those for the light-emitting element 3.

[0332] The light-emitting layer 130 of the comparative light-emitting element 4 was made of 4mCzBPBfpm, Ir(ppz)3, and , so that the weight ratio (4mCzBPBfpm:Ir(ppz)3) is 0.8:0.2 The layer was co-deposited to a thickness of 30 nm. The light-emitting layer 130 of the comparative light-emitting element 4 contains coumarin545T, which is a fluorescent compound. Not included.

[0333] <Preparation of Comparative Light-Emitting Element 5> The comparative light-emitting element 5 is the same as the light-emitting element 3 described above except that the light-emitting layer 130 and the electron transport layer 118 are formed. The only difference was the manufacturing process, and the other steps were the same as those for the light-emitting element 3.

[0334] On the hole transport layer 112, a light emitting layer 130 is formed by using 4,6mCzP2Pm and Ir(ppz) 3, coumarin545T, weight ratio (4,6mCzP2Pm:Ir(ppz) 3: coumarin545T) should be 0.8:0.2:0.005, and the thickness should be In the light-emitting layer 130, coumarin 545 T is a fluorescent compound that is the third organic compound. In this study, 4,6mCzP2Pm, which has a pyrimidine skeleton, is used as the host material. The other configuration is the same as that of the light-emitting element 3.

[0335] Next, on the light-emitting layer 130, a 4,6mCzP2Pm layer was formed as the electron transport layer 118 to a thickness of 1. Then, BPhen was evaporated to a thickness of 5 nm and BPhen to a thickness of 20 nm. On the electron transport layer 118, LiF was evaporated to a thickness of 1 nm as the electron injection layer 119. I arrived.

[0336] <Characteristics of light-emitting element> Next, the characteristics of the light-emitting element 3, the comparative light-emitting element 4, and the comparative light-emitting element 5 prepared above were measured. The measurement method was the same as in Example 1.

[0337] FIG. 17 shows the current efficiency vs. luminance characteristics of the light-emitting element 3, the comparative light-emitting element 4, and the comparative light-emitting element 5. The current-voltage characteristics are shown in FIG. 18, and the external quantum efficiency-luminance characteristics are shown in FIG. The light emitting element 3, the comparative light emitting element 4, and the comparative light emitting element 5 were each 2.5 mA / cm 2 Current density The electroluminescence spectrum when a current was applied at 1000 nm is shown in FIG. The experiment was carried out at room temperature (23°C).

[0338] Also, 1000cd / m 2 The light-emitting element 3, the comparative light-emitting element 4, and the comparative light-emitting element The element characteristics of element 5 are shown in Table 4.

[0339] [Table 4]

[0340] As shown in FIG. 20, the electroluminescence spectra of the light-emitting element 3 and the comparative light-emitting element 5 have peaks The wavelengths were 512 nm, and green light was emitted with full widths at half maximum of approximately 63 nm. Therefore, the light emitted by the light-emitting element 3 and the comparative light-emitting element 5 is due to the fluorescent compound coumar The light emission is due to Ir in545T. (ppz)3 is known to be a compound that emits blue light at low temperatures but does not emit light at room temperature. However, no emission from Ir(ppz)3 was observed.

[0341] The electroluminescence spectrum of the comparative light-emitting element 4 has a peak wavelength of 532 nm and a full luminescence at half maximum of The emission of the comparative light-emitting element 4 was shown in the following. Similarly, the emission from the exciplex formed by 4mCzBPBfpm and Ir(ppz)3 As described above, the light-emitting element 3 according to one embodiment of the present invention exhibited a higher electroluminescence than the comparative light-emitting element 4. The spectrum has a short peak wavelength, a small full width at half maximum, and emits light with high color purity. Therefore, the light-emitting element of one embodiment of the present invention is suitable for a display device.

[0342] 17 and 19 and Table 4, the light-emitting element 3, the comparative light-emitting element 4, and the comparative The comparative light emitting device 5 exhibits high luminous efficiency (current efficiency, power efficiency, and external quantum efficiency). Furthermore, the light-emitting element 3 has an external quantum efficiency of more than 6.25%. In addition to the emission from singlet excitons generated by the recombination of rear (holes and electrons), Emission from triplet excitons, or triplet excitons due to reverse intersystem crossing in exciplexes This is because light emission originating from singlet excitons generated from the light-emitting element 4 is obtained. The light-emitting element 3 is an emission element according to one embodiment of the present invention that uses ExEF. It is an optical element.

[0343] <Time-resolved luminescence measurement> Next, time-resolved luminescence measurements were performed on the light-emitting element 3 and the comparative light-emitting element 4.

[0344] For the measurement, a picosecond fluorescence lifetime measurement system (manufactured by Hamamatsu Photonics) was used. In this measurement, To measure the fluorescence lifetime of the light-emitting element, a rectangular pulse voltage was applied to the light-emitting element, and the light emission that decayed from the fall of the voltage was measured by time-resolved measurement using a streak camera. The pulse voltage was applied at a period of 10 Hz, and by integrating the repeatedly measured data, data with a high S / N ratio was obtained. The measurement was carried out at room temperature (300 K), and the applied pulse voltage was applied in the vicinity of 3 V to 4 V so that the luminance of the light-emitting element was around 100 2 0 cd / m The measurement was carried out under the conditions that the pulse width was 100 μsec, the negative bias voltage was -5 V (when the element drive was OFF), and the measurement time range was 20 μsec. The measurement results are shown in Fig. 21. In Fig. 21, the vertical axis is shown as the intensity normalized by the emission intensity in the state where carriers are constantly injected (when the pulse voltage is ON). The horizontal axis represents the elapsed time from the fall of the pulse voltage. As shown in Fig. 21, the light-emitting element 3 has a faster decay rate of light emission compared to the comparative light-emitting element 4. This means that the excitation energy is quickly converted into light emission. Therefore,

[0345] in the light-emitting layer, even in a state where the exciton density is high (a state where a large amount of current is flowing), light emission can be efficiently extracted. Therefore, as shown in Figs. 17 and 19, the light-emitting element 3 has less roll-off. Thus, the point of having less roll-off is one of the characteristics of the light-emitting element according to one aspect of the present invention.

[0346] <CV measurement results> Next, the electrochemical properties (oxidation reaction properties and reduction reaction properties) of the above compound were measured by cyclic The measurements were performed using an electrochemical analyzer. - (manufactured by BAS Co., Ltd., model number: ALS model 600A or 600C) was used, Each compound was dissolved in N,N-dimethylformamide (DMF) and the solution was measured. In the measurement, the potential of the working electrode relative to the reference electrode was changed in an appropriate range to obtain the oxidation peaks. The redox potential of the reference electrode was -4.9 The peak potential is estimated to be 4 eV. The HOMO and LUMO levels of the compounds were calculated.

[0347] The HOMO level of Ir(ppz)3 calculated from CV measurements is -5.39 eV, and the LUMO level is The HOMO level of 4mCzBPBfpm was -5.91e The V and LUMO levels were -2.97 eV. The HOMO level of 4,6mCzP2Pm was The electron energy level was -5.89 eV and the LUMO level was -2.88 eV.

[0348] As mentioned above, the LUMO level of 4mCzBPBfpm is the same as that of Ir(ppz)3. The HOMO level of Ir(ppz)3 is lower than the HOMO level of 4mCzBPBfpm. Therefore, as in the case of the light-emitting element 3 and the comparative light-emitting element 4, the compound was not included in the light-emitting layer. When this is used, the electrons and holes injected from a pair of electrodes are efficiently transported over a distance of 4m CzBPBfpm and Ir(ppz)3 were injected, respectively, and 4mCzBPBfpm and Ir (ppz)3 can form an exciplex. Similarly, 4,6mCzP2Pm and Ir Therefore, the comparative light-emitting element 5 also has an exciplex formed with (ppz)3. It is a light-emitting element that uses F.

[0349] In addition, the exciplex formed by 4mCzBPBfpm and Ir(ppz)3 is 4mCzB The exciplex has a LUMO level at PBfpm and a HOMO level at Ir(ppz)3. In addition, the LUMO level of 4mCzBPBfpm and the HOMO level of Ir(ppz)3 The energy difference between these two is 2.42 eV. This value is the same as that of the comparative light-emitting element 4 shown in FIG. This roughly coincides with the emission energy (2.33 eV) calculated from the peak wavelength of the optical spectrum. From this, it can be seen that the emission spectrum of the comparative light-emitting element 4 is 4mCzBPBfpm and This is said to be the emission based on the exciplex formed by Ir(ppz)3. Since the difference between the S1 and T1 levels is small, the emission energy is at the S1 and T1 levels of the exciplex. It can be considered as one level of energy (2.33 eV).

[0350] <Relationship between the emission spectrum of exciplexes and the absorption spectrum of guest materials> In addition, the absorption spectrum of coumarin545T in a toluene solution is shown in Figure 22. 22 shows the emission spectra of the exciplex of the comparative light-emitting element 4. The absorption spectrum is shown in Fig. 1. The absorption spectrum was measured using an ultraviolet-visible spectrophotometer (Japan Spectroscopic Corporation). The measurements were carried out at room temperature (an atmosphere maintained at 23°C) using a meter (Model V550, manufactured by the company).

[0351] As shown in FIG. 22, the absorption spectrum of coumarin545T and the comparative light-emitting element 4 are The emission spectra of the exciplexes that are 4mCzBPBfp overlap. The fluorescent compound coumarin is produced from the exciplex formed by m and Ir(ppz)3. It is possible to efficiently supply excitation energy to 545T. With this configuration, As in the electroluminescence spectrum of the light-emitting element 3 shown in FIG. 20, the electroluminescence spectrum of the excitation complex It is possible to provide a light-emitting element that exhibits light emission having a peak wavelength shorter than the peak wavelength of .

[0352] <Measurement of T1 level> Next, in order to determine the T1 level of the compound used in the light-emitting layer 130, a thin film of 4mCzBPBfpm was formed on a quartz substrate by vacuum evaporation , and the emission spectrum of the thin film was measured at low temperature (10K) . For the measurement, a microscopic PL device LabRAM HR-PL (manufactured by Horiba, Ltd. ) was used, the measurement temperature was 10K, a He-Cd laser with a wavelength of 325 nm was used as the excitation light , and a CCD detector was used as the detector.

[0353] As a result, the T1 level of 4mCzBPBfpm was calculated to be 2.68 eV.

[0354] In addition, in order to estimate the T1 level of Ir(ppz)3, the absorption spectrum and the emission spectrum were measured. A dichloromethane solution in which Ir(ppz)3 was dissolved was prepared, and the absorption spectrum was measured using a quartz cell . For the measurement of the absorption spectrum, an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, model V550) was used . From the absorption spectrum of the measured sample, the absorption spectra of the quartz cell and the solvent were subtracted. The measurement was performed at room temperature (atmosphere maintained at 23°C) .

[0355] From the data of the absorption spectrum described above, the absorption edge was determined, and as a result of estimating the transition energy assuming a direct transition , the transition energy of Ir(ppz)3 was calculated to be 3.27 eV. I Since r(ppz)3 is a phosphorescent compound, the lowest energy absorption edge is the triplet excitation. Therefore, the T1 level of Ir(ppz)3 is The absorption edge is calculated to be 3.27 eV.

[0356] From the above measurement results, the T1 level of 4mCzBPBfpm is the same as that of Ir(ppz)3. The T1 level of 4mCzBPBfpm is lower than that of 4mCzBPBfpm and Ir(ppz )3 is larger than the T1 level (2.33 eV) of the exciplex formed with 4mCz The triplet excitation energy of the exciplex formed by BPBfpm and Ir(ppz)3 is 4m It is not inactivated by CzBPBfpm or Ir(ppz)3. The triplet excitation energy of the exciplex is converted into light emission by reverse intersystem crossing. can be converted to doublet excited energy or transferred to a fluorescent compound do.

[0357] In addition, when we attempted to measure the emission spectrum of Ir(ppz)3 at room temperature, In Non-Patent Document 1, the luminescence quantum yield of Ir(ppz)3 was It is reported that the solubility of Ir(ppz)3 at room temperature is less than 1%. It can be seen that the material does not emit light. In other words, the compound has a low luminescence quantum yield of less than 1%. Even in the case where an organic EL element is used, a light-emitting element having high luminous efficiency can be obtained.

[0358] <Reliability of light-emitting elements> FIG. 23 shows the results of the constant current drive of the light-emitting element 3, the comparative light-emitting element 4, and the comparative light-emitting element 5 at 0.5 mA. 23 shows the results of dynamic test. As shown in FIG. 23, the light-emitting element 3 has a higher luminance than the comparative light-emitting element 4 and the comparative light-emitting element 5. The light-emitting element 3 and the comparative light-emitting element 4 have good reliability. As described above, the light-emitting element 3 emits light from a fluorescent compound, the comparative light-emitting element emits light from a comparative compound, and the comparative light-emitting element emits light from a comparative compound. Light emission from the exciplex is obtained from molecule 4. It has been found that obtaining light emission from fluorescent compounds is more reliable. The difference between the light-emitting element 3 and the comparative light-emitting element 5 is the host material. The light-emitting element 4 is a light-emitting element having a benzofuropyrimidine skeleton as a host material. The materials used are those with pyrimidine skeletons. By using a material having a rimidine skeleton, a light-emitting element with high reliability can be obtained. Cut.

[0359] As described above, according to one embodiment of the present invention, a light-emitting element having high emission efficiency and good reliability can be provided. According to one embodiment of the present invention, a light-emitting element with low driving voltage and low power consumption can be provided. It can be provided. EXAMPLES

[0360] In this example, a manufacturing example of a light-emitting element according to one embodiment of the present invention and a comparative light-emitting element will be described. The structure of the light-emitting element manufactured in this example is the same as that shown in Figure 1 (A). The details of the element structure are shown in Table 5. The structures and abbreviations of the compounds used are shown below. The structures and abbreviations of other compounds are shown in the actual examples. Please refer to Example 1.

[0361] [ka]

[0362] [Table 5]

[0363] <Fabrication of light-emitting element> A method for manufacturing the light-emitting element manufactured in this embodiment will be described below.

[0364] <Fabrication of light-emitting element 6> An ITSO film was formed on a glass substrate as an electrode 101 to a thickness of 70 nm. The electrode area of ​​the electrode 101 is 4 mm 2 (2mm x 2mm).

[0365] Next, a hole injection layer 111 made of DBT3P-II and molybdenum oxide was formed on the electrode 101. (MoO3) and the weight ratio (DBT3P-II:MoO3) was 1:0.5. The deposition was carried out to a thickness of 45 nm.

[0366] Next, 4,4'-diphenyl-4" -(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCB BiBP) was evaporated to a thickness of 20 nm.

[0367] Next, 4,8-bis[3-(dibenzothiophene)-2,4-diphenyl ether (DTA)-1,4-dimethylphenyl ether (DTA)-1,4-di ... 4-phenyl-4-ylphenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4 ,8mDBtP2Bfpm) and 9-phenyl-9H-3-(9-phenyl-9H-cal carbazole-3-yl)carbazole (abbreviation: PCCP), [2-(4-phenyl-2-pyridyl)carbazole 2-(2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC] ]Iridium(III) (abbreviation: Ir(ppy)2(4dppy)) and 2,8-di-t ert-Butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyl Nyltetracene (abbreviation: TBRb) and in a weight ratio of (4,8mDBtP2Bfpm:PCC P:Ir(ppy)2(4dppy):TBRb) was 0.6:0.4:0.1:0.01 The light-emitting layer 130 was co-deposited to a thickness of 40 nm. TBRb is a fluorescent compound.

[0368] Next, on the light-emitting layer 130, 4,8mDBtP2Bfpm is formed as the electron transport layer 118. The thickness of the ZnO layer was 20 nm, and the thickness of the NBPhen layer was 10 nm. Next, LiF was deposited on the electron transport layer 118 to form an electron injection layer 119 with a thickness of 1 nm. It was evaporated like this.

[0369] Next, on the electron injection layer 119, aluminum (Al) was deposited to a thickness of 20 It was formed so that the thickness was 0 nm.

[0370] Next, in a glove box with a nitrogen atmosphere, a glass substrate for sealing is The EL sealant is used to fix the organic material to the glass substrate, forming a light-emitting element 6. Specifically, a sealant was applied to the periphery of the organic material formed on the glass substrate, and the The glass substrate and the sealing glass substrate are bonded together, and ultraviolet light with a wavelength of 365 nm is applied for 6 hours. J / cm 2 The light-emitting element 6 was obtained by the above steps.

[0371] <Preparation of Comparative Light-Emitting Element 7> The comparative light-emitting element 7 differs from the light-emitting element 6 described above only in the process of forming the light-emitting layer 130. The other steps were the same as those for the light-emitting element 6.

[0372] The light-emitting layer 130 of the comparative light-emitting element 7 was made of 4.8mDBtP2Bfpm, PCCP, and Ir(ppy)2(4dppy) was mixed in a weight ratio of (4,8mDBtP2Bfpm:PCCP:I r(ppy)2(4dppy)) is 0.6:0.4:0.1 and the thickness is 4 The light-emitting layer 130 of the light-emitting element 6 was co-deposited to a thickness of 0 nm. The light-emitting layer 130 of No. 7 does not contain TBRb, which is a fluorescent compound.

[0373] <Preparation of Comparative Light-Emitting Element 8> The comparative light-emitting element 8 is the same as the light-emitting element 6 described above except that the light-emitting layer 130 and the electron transport layer 118 are formed in the same manner. The only difference was the manufacturing process, and the other steps were the same as those for the light-emitting element 6.

[0374] The light-emitting layer 130 of the comparative light-emitting element 8 was made of 4,6-bis[3-(dibenzothiophene-4 -yl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II) and PCCP , Ir(ppy)2(4dppy) and TBRb in a weight ratio of (4,6mDBTP2Pm-I I:PCCP:Ir(ppy)2(4dppy):TBRb) is 0.6:0.4:0.1 The light-emitting element 6 was co-evaporated so that the thickness of the layer was 40 nm. In comparison with the light-emitting layer 130 of the comparative light-emitting element 8, the light-emitting layer 130 of the comparative light-emitting element 8 contains pyrimidine as a host material. Compounds having a dimethylamino group skeleton are used.

[0375] Next, on the light-emitting layer 130, 4,6mDBTP2Pm-II was deposited as the electron transport layer 118. The layers were evaporated in order to a thickness of 20 nm, and then NBPhen was evaporated in order to a thickness of 10 nm. Ta.

[0376] <Characteristics of light-emitting element> Next, the characteristics of the light-emitting element 6, the comparative light-emitting element 7, and the comparative light-emitting element 8 prepared above were measured. The measurement method was the same as in Example 1.

[0377] FIG. 24 shows the current efficiency vs. luminance characteristics of the light-emitting element 6, the comparative light-emitting element 7, and the comparative light-emitting element 8. The current-voltage characteristics are shown in FIG. 25, and the external quantum efficiency-luminance characteristics are shown in FIG. The light emitting element 6, the comparative light emitting element 7, and the comparative light emitting element 8 were each 2.5 mA / cm 2 Current density The electroluminescence spectrum when a current was applied at 1000 nm is shown in FIG. The experiment was carried out at room temperature (23°C).

[0378] Also, 1000cd / m 2 The light-emitting element 6, the comparative light-emitting element 7, and the comparative light-emitting element The device characteristics of element 8 are shown in Table 6.

[0379] [Table 6]

[0380] As shown in FIG. 27, the electroluminescence spectra of the light-emitting element 6 and the comparative light-emitting element 8 have peaks The wavelengths were 563 nm, and yellow light was emitted with full widths at half maximum of approximately 72 nm. Therefore, the light emitted by the light-emitting element 6 and the comparative light-emitting element 8 is due to the fluorescent compound TBRb. The light emitted from the light-emitting element 6 and the comparative light-emitting element 8 was Ir(ppy)2(4d py) was not observed.

[0381] The emission spectrum of the comparative light-emitting element 7 has a peak wavelength of 557 nm and a full width at half maximum of The emission from the comparative light-emitting element 7 was characterized by a broad spectrum shape of Ir(pp y)2(4dpy)-derived light emission. Thus, the light-emitting element according to one aspect of the present invention 6 has a smaller full width at half maximum of the electroluminescence spectrum and higher color purity than the comparative light-emitting element 7, and can exhibit light emission. Therefore, one aspect of the present invention is suitable for a display device.

[0382] Also, as shown in FIGS. 24 and 26 and Table 6, the light-emitting element 6, the comparative light-emitting element 7, and the comparative light-emitting element 8 exhibit very high luminous efficiency (current efficiency, power efficiency, and external quantum efficiency). In addition, the light-emitting element 6 has a very high efficiency with an external quantum efficiency far exceeding 6.25%. This is because, in addition to the light emission derived from singlet excitons generated by the recombination of carriers (holes and electrons), light emission derived from triplet excitons is obtained. This indicates that excitation energy is transferred from the phosphorescent material Ir(ppy)2(4dppy) to the fluorescent compound TBRb. Also, since the light-emitting element 6 exhibits a higher external quantum efficiency than the comparative light-emitting element 7, it can be seen that the deactivation of excitation energy is suppressed and the excitation energy can be efficiently converted into light emission. In addition, the light-emitting element 6 has little roll-off. Thus, the little roll-off is one of the characteristics of the light-emitting element according to one aspect of the present invention.

[0383]

[0384] <CV measurement results> Next, the HOMO level and the LUMO level were calculated by cyclic voltammetry (CV) measurement of the electrochemical characteristics (oxidation reaction characteristics and reduction reaction characteristics) of the above compounds. The measurement method was the same as that in Example 2 shown above.

[0385] From the CV measurements, the HOMO level of 4,8mDBtP2Bfpm is -6.18 eV, and the LUMO The HOMO level of PCCP is -3.02 eV, the LUMO level is -1. .96 eV. The HOMO level of 4,6mDBTP2Pm-II is -6.22 The LUMO level was -2.83 eV.

[0386] Therefore, 4,8mDBtP2Bfpm has a higher HOMO level and a lower LUMO level than PCCP. Therefore, 4,8mDBtP2Bfpm and PCCP have the following levels in the light-emitting layer: This is a combination that forms an exciplex. Similarly, 4,6mDBTP2Pm-II and PCC P also forms an exciplex.

[0387] In addition, the emission spectrum of the exciplex formed from 4,8mDBtP2Bfpm and PCCP The S1 and T1 levels calculated from the emission energy calculated from the peak wavelength are 2.6 1 eV. Here, the T1 level of Ir(ppy)2(4dpy) is 2.40 eV (dichloro). (Calculated from the absorption edge of the fluorine-containing solution) Both the energy and triplet excitation energy can be transferred to Ir(ppy)2(4dpy). Cut.

[0388] <Relationship between the emission spectrum of exciplexes and the absorption spectrum of guest materials> In addition, Figure 28 shows the results of measuring the absorption spectrum of TBRb in a toluene solution. FIG. 28 also shows the emission spectrum of the comparative light-emitting element 7. The same procedure was followed as in the example shown.

[0389] As shown in FIG. 28, the absorption spectrum of TBRb and the emission spectrum of the comparative light-emitting element 7 are Therefore, the 4,8mDBtP2Bfpm and PCCP form The fluorescent compound TBRb is generated via Ir(ppy)2(4dpy) from the exciplex. It is possible to efficiently provide excitation energy to the phosphorescent compound Ir(pp Triplet excitation occurs by energy transfer to TBRb via y)2(4dpy). The energy can be contributed to fluorescent emission. may also occur.

[0390] Here, the light-emitting element 6 has a better light-emitting efficiency than the comparative light-emitting element 8. The difference is the host material. Light-emitting element 6 is made of a material having a benzofuropyrimidine skeleton. The light-emitting element 8 is made of a material having a pyrimidine skeleton. By using a material having a benzofuropyrimidine skeleton, it is possible to obtain a light-emitting element with higher luminous efficiency. You can get a child.

[0391] <Reliability of light-emitting elements> Next, for the light-emitting element 6, the comparative light-emitting element 7, and the comparative light-emitting element 8, a constant voltage of 2 mA was A flow drive test was performed. Table 7 shows the LT 40 (Time for brightness to decrease by 60%).

[0392] [Table 7]

[0393] As can be seen from Table 7, the light-emitting element 6, which is a light-emitting element of one embodiment of the present invention, showed the best reliability. The difference between the element 6 and the comparative light-emitting element 7 is the presence or absence of a fluorescent compound. It has been shown that the reliability is improved by the energy transfer to the fluorescent material via the In addition, the reliability of the light-emitting element 6 is higher than that of the comparative light-emitting element 8. As in Example 2, the reliability was improved by using a material having a benzofuropyrimidine skeleton. It was found that a good light emitting element could be obtained. [Explanation of symbols]

[0394] 100 EL layer 101 Electrode 102 electrode 106 Light Emitting Unit 108 Light Emitting Unit 111 Hole injection layer 112 Hole transport layer 113 Electron transport layer 114 Electron injection layer 115 Charge generation layer 116 Hole injection layer 117 Hole transport layer 118 Electron transport layer 119 Electron injection layer 120 Light-emitting layer 130 Light-emitting layer 131 compounds 132 compounds 133 Compound 134 compounds 150 Light emitting element 170 Light-emitting layer 250 Light emitting element 601 Source side driver circuit 602 Pixel section 603 Gate side drive circuit 604 Sealing substrate 605 Sealing material 607 Space 608 Wiring 609 FPC 610 Element Substrate 611 Switching TFT 612 Current Control TFT 613 Electrode 614 Insulation 616 EL layer 617 Electrode 618 Light-emitting element 623 n-channel TFT 624 p-channel TFT 625 Dry material 900 Mobile Information Terminal 901 Case 902 Case 903 Display section 905 Hinge part 910 Mobile Information Terminal 911 Case 912 Display section 913 Operation button 914 External connection port 915 Speaker 916 Mike 917 Camera 920 Camera 921 Case 922 Display section 923 Operation button 924 Shutter button 926 Lens 1001 Board 1002 Undercoat insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 Gate electrode 1020 Interlayer insulating film 1021 Interlayer insulating film 1022 Electrode 1024B Electrode 1024G electrode 1024R electrode 1024W electrode 1025B Lower electrode 1025G bottom electrode 1025R lower electrode 1025W bottom electrode 1026 Bulkhead 1028 EL layer 1029 Electrode 1030 Black layer 1031 Sealing substrate 1032 Sealing material 1033 Base material 1034B Colored layer 1034G colored layer 1034R colored layer 1035 Black layer 1036 Overcoat layer 1037 Interlayer insulating film 1040 Pixel section 1041 Drive circuit section 1042 Periphery 1044B Blue pixel 1044G green pixels 1044R Red pixel 1044W white pixels 2100 Robot 2101 Illuminance sensor 2102 Microphone 2103 Upper Camera 2104 Speaker 2105 Display 2106 Lower Camera 2107 Obstacle Sensor 2108 Moving mechanism 2110 Arithmetic equipment 5000 cabinet 5001 Display section 5002 Display section 5003 Speaker 5004 LED Lamp 5005 Operation key 5006 Connection terminal 5007 Sensor 5008 Microphone 5012 Support part 5013 Earphones 5100 Cleaning robot 5101 Display 5102 Camera 5103 Brush 5104 Operation button 5120 Garbage 5140 Portable electronic devices 5150 Portable Information Terminal 5151 Case 5152 indicates the field 5153 Flexion part 8501 Lighting fixtures 8502 Lighting fixtures 8503 Lighting devices 8504 Lighting fixtures

Claims

1. A light-emitting layer is disposed between a pair of electrodes, the light-emitting layer includes a first organic compound, a second organic compound, and a third organic compound; the first organic compound has a function of converting triplet excitation energy into luminescence, the second organic compound has a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton, the benzofuropyrimidine skeleton is a benzofuro[3,2-d]pyrimidine skeleton, the benzothienopyrimidine skeleton is a benzothieno[3,2-d]pyrimidine skeleton, the third organic compound has a function of converting singlet excitation energy into luminescence, a light-emitting element, wherein the light emitted by the light-emitting layer includes light emitted by the third organic compound;

2. In claim 1, The first organic compound has a function of providing excitation energy to the third organic compound.

3. In claim 2, The light-emitting element has a substituent at the 4-position or the 8-position of the benzofuro[3,2-d]pyrimidine skeleton or the benzothieno[3,2-d]pyrimidine skeleton.

4. In any one of claims 1 to 3, The first organic compound is a light-emitting element having a function of exhibiting phosphorescence.

5. In any one of claims 1 to 4, The first organic compound has a light emitting quantum yield of 0% or more and 40% or less at room temperature.

6. In any one of claims 1 to 5, The third organic compound is a light-emitting element that exhibits fluorescence.

7. In any one of claims 1 to 6, a light-emitting element, wherein an energy difference between a singlet excitation energy and a triplet excitation energy of the first organic compound is 0 eV or more and 0.2 eV or less.

8. A light emitting element according to any one of claims 1 to 7, At least one of a color filter or a transistor; A display device having the above configuration.

9. A display device according to claim 8; At least one of a housing or a touch sensor; An electronic device having the

10. A light emitting element according to any one of claims 1 to 7, At least one of a housing or a touch sensor; A lighting device having the above structure.

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