Organic light-emitting element

Abstract

To provide an organic light-emitting element having excellent durability at low voltage.SOLUTION: An organic light-emitting element includes a first light-emitting unit and a second light-emitting unit that sandwich a charge generation portion, the charge generation portion having an n-type charge generation layer containing at least a first organic compound and a second organic compound, the first organic compound and the second organic compound satisfying a relation indicated by the following formulae [1] and [2-1]: |LUMO(H1)-LUMO(H2)|≤0.1ev [1]; HOMO(H2)-HOMO(H1)>0.0 eV [2-1], where LUMO(H1) represents a LUMO energy level of a first organic compound, LUMO(H2) represents a LUMO energy level of a second organic compound, HOMO(H1) represents a HOMO energy level of the first organic compound, and HOMO(H2) represents a HOMO energy level of the second organic compound.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an organic light-emitting element and various devices and apparatuses having the organic light-emitting element. [Background technology]

[0002] An organic electroluminescence element (hereinafter also referred to as an "organic EL element" or an "organic light-emitting element") is an element that emits light when electricity is passed through an organic compound layer that includes an anode, a cathode, and a light-emitting layer disposed between these electrodes. In recent years, in addition to single-color organic light-emitting devices that emit white light by having light-emitting materials that emit red, green, and blue light in one light-emitting layer, stacked organic light-emitting devices in which light-emitting layers that emit red, green, and blue light respectively are stacked have been developed. Since stacked organic light-emitting devices tend to have a higher driving voltage than single-layer organic light-emitting devices, a structure in which an intermediate layer called a charge generating section or intermediate electrode is provided is known. The intermediate layer may be more susceptible to deterioration than other organic layers. Since deterioration of the intermediate layer leads to higher voltages, lower efficiency, and reduced durability, there is a demand for the development of a stable charge generating layer. Patent Document 1 describes a structure in which an n-type charge generation layer is made of at least two materials having different LUMOs, and Patent Document 2 describes a structure in which an n-type charge generation layer uses an organic compound having a pyrene skeleton. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2015 / 0090984 [Patent Document 2] US Patent Application Publication No. 2016 / 0104844 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the stacked organic light-emitting device described in Patent Document 1, the n-type charge generation layer is composed of two or more materials with different LUMOs, so that the electron trap level is generated, and the electron mobility in the n-type charge generation layer may decrease. As a result, the voltage of the organic light-emitting device may increase. In addition, in the stacked organic light-emitting device described in Patent Document 2, the organic compound contained in the n-type charge generation layer has a heterocycle as a substituent in the pyrene skeleton. Compounds having a heterocyclic group may have low stability against holes. Therefore, the stacked organic light-emitting device disclosed in Patent Document 2 has room for improvement in the durability of the n-type charge generation layer. The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic light-emitting device which operates at a low voltage and has excellent durability. [Means for solving the problem]

[0005] One embodiment of the organic light-emitting device according to the present invention is an organic light-emitting device including, in this order, a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a second electrode, The charge generating section includes at least one n-type charge generating layer, the n-type charge generating layer includes at least a first organic compound and a second organic compound; The organic light-emitting device is characterized in that the first organic compound and the second organic compound satisfy the relationship represented by the following formulas [1] and [2-1]. |LUMO(H1)-LUMO(H2)|≦0.1ev [1] HOMO(H2)-HOMO(H1)>0.0eV [2-1] (In the above formulas [1] and [2-1], LUMO(H1) represents the LUMO energy level of the first organic compound, LUMO(H2) represents the LUMO energy level of the second organic compound, HOMO(H1) represents the HOMO energy level of the first organic compound, and HOMO(H2) represents the HOMO energy level of the second organic compound.) Another embodiment of the organic light-emitting device according to the present invention is an organic light-emitting device including, in this order, a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a second electrode, The charge generating section includes at least one n-type charge generating layer, the n-type charge generating layer includes at least a first organic compound and a second organic compound; the first organic compound is a nitrogen-containing aromatic compound; The organic light-emitting device is characterized in that the second organic compound is represented by the following general formula [I] or [II]:

[0006] [ka] [In the above general formulas [I] and [II], X1 to X8 are carbon atoms having a substituent R, or nitrogen atoms. Y represents a carbon atom having substituents R1 and R2, or any one of an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. When Y in general formula [I] is a carbon atom having substituents R1 and R2, and in general formula [II], at least one of X1 to X8 represents a nitrogen atom. R, R1, and R2 are selected from a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted amino group, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkoxy group, and a cyano group. In X1 to X8, when the carbon atoms having the substituent R are adjacent to each other and the substituent R has a carbon atom, or when R1 and R2 have a carbon atom, the adjacent substituents may form a ring.] Effect of the Invention

[0007] According to the present invention, it is possible to provide an organic light-emitting element which operates at a low voltage and has excellent durability. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view showing an example of an embodiment of an organic light-emitting element according to an embodiment of the present invention. [Diagram 2] 1A is a schematic cross-sectional view showing an example of a pixel of a display device according to one embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view showing an example of a display device using an organic light-emitting element according to one embodiment of the present invention. [Diagram 3] FIG. 1 is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention. [Figure 4] 1A is a schematic diagram illustrating an example of an imaging device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of an electronic device according to an embodiment of the present invention. [Diagram 5] 1A is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of a foldable display device. [Figure 6] 1A is a schematic diagram showing an example of an illumination device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram showing an example of an automobile having a vehicle lamp according to an embodiment of the present invention. [Figure 7] 1A is a schematic diagram showing an example of a wearable device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram showing an example of a wearable device according to an embodiment of the present invention, the wearable device having an imaging device. [Figure 8] 1A is a schematic diagram showing an example of an image forming apparatus according to an embodiment of the present invention, FIG. 1B is a schematic diagram showing an example of an exposure light source of the image forming apparatus according to an embodiment of the present invention, and FIG. 1C is a schematic diagram showing an example of an exposure light source of the image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <First organic light-emitting element> A first embodiment of the organic light-emitting device according to the present invention includes a first electrode, a first light-emitting unit, a charge generation section, a second light-emitting unit, and a second electrode, in this order, and the charge generation section includes at least one n-type charge generation layer. The n-type charge generation layer includes at least a first organic compound and a second organic compound, and the first organic compound and the second organic compound satisfy the following formulas [1] and [2-1].

[0010] |LUMO(H1)-LUMO(H2)|≦0.1ev [1] HOMO(H2)-HOMO(H1)>0.0eV [2-1] LUMO(H1): LUMO energy level of the first organic compound LUMO(H2): LUMO energy level of the second organic compound HOMO(H1): HOMO energy level of the first organic compound HOMO(H2): HOMO energy level of the second organic compound In addition, HOMO means the highest occupied molecular orbital, and LUMO means the lowest unoccupied molecular orbital. The HOMO energy level is sometimes called the "HOMO" or "HOMO level", and the LUMO energy level is sometimes called the "LUMO" or "LUMO level". The unit is "eV".

[0011] The organic light-emitting element according to this embodiment may have a third light-emitting unit in addition to the first light-emitting unit and the second light-emitting unit. The third light-emitting unit may be provided between the first electrode and the first light-emitting unit, between the first light-emitting unit and the second light-emitting unit, or between the second light-emitting unit and the second electrode.

[0012] In the organic light-emitting device according to this embodiment, the first electrode may be an anode, and the second electrode may be a cathode. In addition, the organic light-emitting device according to this embodiment may have an element configuration capable of emitting white light. Specifically, the first light-emitting unit may emit red and green light, and the second light-emitting unit may emit blue light. The first light-emitting unit, the second light-emitting unit, and the third light-emitting unit may emit red, green, and blue light, respectively. In addition, the organic light-emitting device according to this embodiment may have an element configuration capable of emitting light other than white light. Specifically, the first light-emitting unit and the second light-emitting unit may emit light of the same color. By having such an element configuration, an organic light-emitting device with improved brightness can be manufactured.

[0013] The present invention will now be described in more detail with reference to FIG. FIG. 1 is a schematic cross-sectional view of one embodiment of an organic light-emitting element according to the present invention, in which a first electrode 200, a first light-emitting unit 300, a charge generating section 400, a second light-emitting unit 500, and a second electrode 600 are laminated in this order on a substrate 1. In the organic light-emitting device according to this embodiment, the first light-emitting unit 300 has a first light-emitting layer 304. The first light-emitting layer 304 contains at least a third organic compound and a first light-emitting compound. The first light-emitting layer 304 may contain a fourth organic compound, if necessary. The first light-emitting unit 300 may have other layers, if necessary. In the organic light-emitting device according to this embodiment, specifically, the first light-emitting unit 300 may have a first hole injection layer 301, a first hole transport layer 302, a first electron blocking layer 303, a first light-emitting layer 304, a first hole blocking layer 305, a first electron transport layer 306, and a first electron injection layer 307.

[0014] In the organic light-emitting device according to this embodiment, the second light-emitting unit 500 has a second light-emitting layer 503. The second light-emitting layer 503 contains a fifth organic compound and at least a second light-emitting compound, and may contain a sixth organic compound and a third light-emitting compound as necessary. The second light-emitting unit 500 may have other layers as necessary. Specifically, the second light-emitting unit 500 may have a second hole transport layer 501, a second electron blocking layer 502, a second light-emitting layer 503, a second hole blocking layer 504, a second electron transport layer 505, and a second electron injection layer 506.

[0015] In the organic light-emitting device according to this embodiment, the charge generating section 400 has at least one n-type charge generating layer. The charge generating section 400 plays a role of injecting electrons into the first light-emitting unit. Therefore, the organic light-emitting device according to this embodiment does not need to have the first electron injection layer 307. By not providing the first electron injection layer 307, it is expected that the driving voltage of the organic light-emitting device according to this embodiment can be reduced.

[0016] Furthermore, when the organic light-emitting device according to this embodiment has the first electron injection layer 307, it is preferable that the first electron injection layer 307 is provided adjacent to the n-type charge generation layer, and that the n-type charge generation layer and the first electron injection layer 307 have a common material. In this case, the adhesion between the n-type charge generation layer and the first electron injection layer 307 is increased, and therefore the function as an electron injection layer can be further improved.

[0017] Here, the third organic compound contained in the first light-emitting layer 304 and the fifth organic compound contained in the second light-emitting layer 503 are host compounds, and the fourth organic compound contained in the first light-emitting layer 304 and the sixth organic compound contained in the second light-emitting layer 503 are assist compounds. In addition, the first light-emitting compound contained in the first light-emitting layer 304 and the second light-emitting compound and the third light-emitting compound contained in the second light-emitting layer 503 are guest compounds.

[0018] Here, the host compound is the compound with the largest mass ratio among the compounds constituting the light-emitting layer. The guest compound is the compound with a smaller mass ratio than the host compound among the compounds constituting the light-emitting layer, and is the compound that is mainly responsible for emitting light. The assist compound is the compound with a smaller mass ratio than the host compound among the compounds constituting the light-emitting layer, and assists the emission of the guest compound. The assist compound is also called the second host compound.

[0019] A specific configuration of the charge generating section 400 according to this embodiment will be described below, but the present invention is not limited to this. (i) n-type charge generation layer / hole injection layer (ii) n-type charge generation layer / p-type charge generation layer (iii) n-type charge generating layer / connecting layer / hole injection layer (iv) n-type charge generating layer / connecting layer / p-type charge generating layer

[0020] In the organic light-emitting device according to this embodiment, the n-type charge generation layer is a mixed layer containing a first organic compound and a second organic compound. The n-type charge generation layer may have an organic compound having high electron donor properties, such as an alkali metal atom, an alkaline earth metal atom, or a compound having an imidazolidine skeleton, and preferably contains an alkali metal atom or an alkaline earth metal atom. The p-type charge generation layer may be a mixed layer containing a hole transporting compound and an electron withdrawing compound. The hole injection layer may be a layer containing an electron withdrawing compound or a metal oxide. The connection layer may be a layer containing an electron transporting compound or a hole transporting compound.

[0021] Examples of alkali metal atoms include, but are not limited to, lithium, sodium, potassium, rubidium, and cesium atoms, with lithium and cesium atoms being preferred. Examples of alkaline earth metal atoms include, but are not limited to, beryllium atoms, magnesium atoms, calcium atoms, and strontium atoms.

[0022] The first organic compound is, for example, a nitrogen-containing aromatic compound.Specific examples include phenanthrolinyl, oxazolyl, oxadiazolyl, diazolyl, thiadiazolyl, triazolyl, naphthyridinyl, and derivatives thereof.Among these, the first organic compound is preferably a phenanthroline derivative or a naphthyridine derivative.Phenanthroline derivatives and naphthyridine derivatives have particularly strong interactions with alkali metals, and are therefore particularly preferred as materials for n-type charge generating layers. As the second organic compound, an aromatic hydrocarbon compound or an aromatic heterocyclic compound is preferably used.

[0023] The configuration of the first organic light-emitting device according to the present invention has the following features.

[0024] (1-1) The first organic compound and the second organic compound of the n-type charge generating layer satisfy the relationship of the following formula [1]. |LUMO(H2)-LUMO(H1)|≦0.1eV [1]

[0025] In the organic light-emitting device according to this embodiment, by satisfying the relationship of the above formula [1], the electron mobility in the n-type charge generating layer can be improved, and therefore the voltage of the organic light-emitting device according to this embodiment can be further reduced.

[0026] Table 1 below shows a comparison of the voltage and durability of organic light-emitting elements of Examples 1, 2, and 9 and Comparative Example 1 described later. In the table, the "No." of the first organic compound and the second organic compound are the respective example compound numbers described later, and the ΔHOMO and ΔLUMO are as follows. The voltage ratio and durability ratio are relative values ​​when the voltage and durability of Comparative Example 1 are set to 1.0, respectively. ΔHOMO = HOMO(H2) - HOMO(H1) ΔLUMO=|LUMO(H1)-LUMO(H2)| "1-a" in Table 1 is as follows.

[0027] [ka]

[0028] [Table 1]

[0029] As described above, the n-type charge generation layer plays a role of injecting and transporting electrons to the light-emitting layer. More specifically, the nitrogen-containing aromatic compound, typified by ET1(BPhen), used as the first organic compound, interacts with alkali metal atoms and alkaline earth metal atoms to exert electron injection properties and electron transport properties in the n-type charge generation layer.

[0030] Here, when the LUMO level difference between the first organic compound and the second organic compound is large, an electron trap level is generated, and the electron mobility in the n-type charge generating layer may decrease. As a result, the voltage of the organic light emitting device may increase. Therefore, in the organic light emitting device according to this embodiment, it is preferable that the LUMO level difference between the first organic compound and the second organic compound is small. In other words, it is preferable that the first organic compound and the second organic compound satisfy the relationship of formula [1].

[0031] When the first organic compound and the second organic compound satisfy the relationship of formula [1], the n-type charge generation layer is less likely to trap electrons, and the electron mobility in the n-type charge generation layer is improved, resulting in a further reduction in the voltage of the organic light-emitting device according to this embodiment.

[0032] The difference between the absolute value of LUMO(H1) and the absolute value of LUMO(H2) may be less than 0.1 eV, because within this range, there is almost no difference in the LUMO levels of the first organic compound and the second organic compound, and one of them does not have an electron trapping property for the other.

[0033] (1-2) The first organic compound and the second organic compound of the n-type charge generating layer satisfy the relationship of formula [1] and formula [2-1] at the same time. HOMO(H2)-HOMO(H1)>0.0eV [2-1]

[0034] The first organic compound is unstable to holes because it exerts electron injection properties and also electron transport properties in the n-type charge generation layer. The second organic compound described in Table 1 is designed to have a higher HOMO level (closer to the vacuum level) than ET1 used as the first organic compound so as to simultaneously satisfy the relationship of formula [2-1]. Therefore, the second organic compound is configured to trap holes, which can suppress the deterioration of the first organic compound due to holes, and the deterioration of the entire n-type charge generation layer can be suppressed, thereby suppressing the deterioration of the luminance of the organic light-emitting device.

[0035] Furthermore, the organic light-emitting device according to the present invention preferably satisfies the relationship of the following formula [2-2] in addition to the formula [1]. HOMO(H2)-HOMO(H1)≧0.2eV [2-2]

[0036] As shown in Examples 2 and 9 in Table 1, the durability is further improved by increasing the hole trapping ability of the second organic compound in the n-type charge generation layer. When the charge generation section has a p-type charge generation layer, the p-type charge generation layer may be a mixed layer containing a hole transporting compound and an electron withdrawing compound, and the electron withdrawing compound plays a role of pulling out electrons from the hole transporting compound, but has an unstable property with respect to holes, which are the opposite charge. By satisfying the above formula [2-2], the deterioration of the first organic compound is suppressed, and the n-type charge generation layer has a hole trap structure, which makes it difficult for holes to reach the p-type charge generation layer, so that the deterioration of the organic light-emitting element can be suppressed.

[0037] As described above, by simultaneously satisfying the relationship of formula [1] and formula [2-1], and more preferably by simultaneously satisfying the relationship of formula [1] and formula [2-2], the n-type charge generation layer exhibits both electron transporting and hole trapping properties, and as shown in Table 1, the organic light-emitting device can be driven at a lower voltage and its durability is improved.

[0038] The organic light-emitting device according to the present invention preferably has the following configuration (1-3). (1-3) A first light-emitting unit has a first light-emitting layer, the first light-emitting layer contains at least a third organic compound and a first light-emitting compound, and the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [3]: LUMO(H3)-LUMO(D1)>HOMO(D1)-HOMO(H3) [3] LUMO(H3): LUMO energy level of the third organic compound LUMO(D1): LUMO energy level of the first emissive compound HOMO(H3): HOMO energy level of the third organic compound HOMO(D1): HOMO energy level of the first emissive compound

[0039] The above formula [3] indicates that the first light-emitting layer is an electron trap type. When the number of holes in the light-emitting layer increases, the excitons generated in the light-emitting layer are accelerated to degrade through a cationic state. For this reason, in the present invention, a structure in which holes are not trapped in the light-emitting layer of the first light-emitting unit, that is, a structure of the electron trap type, is particularly preferable. In other words, it is more preferable that holes are not trapped in the light-emitting layer, but are trapped in another layer.

[0040] It is preferable that the first light-emitting layer satisfies the relationship represented by the following formula [4]. LUMO(H3)-LUMO(D1)≧0.1 eV [4] The above formula [4] indicates that the LUMO level difference in the first light-emitting layer is sufficient to exhibit a sufficient electron trapping property.

[0041] Preferably, the first light-emitting layer further contains a fourth organic compound, and the third organic compound and the fourth organic compound satisfy the relationship represented by the following formula [5]. HOMO(H4)-HOMO(H3)≧0.1 eV [5] HOMO(H4): HOMO energy level of the fourth organic compound The above formula [5] indicates that the fourth organic compound traps holes, and by introducing such an organic compound as an assist material into the light-emitting layer, the light-emitting layer can trap both electrons and holes. This makes it possible to suppress leakage of holes to the n-type charge generating layer, improving the durability of the organic light-emitting device.

[0042] As described above, since the present invention has a configuration in which holes easily leak from the light-emitting layer, it is preferable to trap the holes in another layer. In particular, as shown in (1-2) above, the first organic compound and the second organic compound in the n-type charge generation layer satisfy the relationship of formula [2-1], so that the holes can be trapped in the n-type charge generation layer.

[0043] In this specification, the closer the HOMO and LUMO are to the vacuum level, the higher they are, and the further away they are from the vacuum level, the lower they are. The LUMO of the charge generating layer being lower than the HOMO of the hole transporting layer means that the LUMO of the charge generating layer is farther away from the vacuum level than the HOMO of the hole transporting layer.

[0044] The HOMO and LUMO can be calculated by molecular orbital calculations. The molecular orbital calculations may be performed by density functional theory (DFT) or the like, using B3LYP as the functional and 6-31G* as the basis function.Gaussian09(Gaussian09,RevisionC.01,MJFrisch,GWTrucks,HBSchlegel,GEScuseria,MARobb, JRCheeseman,G.Scalmani,V.Barone,B.Mennucci,GAPetersson,H.Nakatsuji,M.Caricato,X.Li,HPHratchian,AF Izmailov,J.Bloino,G.Zheng,JLSonnenberg,M.Hada,M.Ehara,K.Toyota,R.Fukuda,J.Hasegawa,M.Ishida,T.Nak ajima,Y.Honda,O.Kitao,H.Nakai,T.Vreven,JAMontgomery,Jr.,JEPeralta,F.Ogliaro,M.Bearpark,JJHeyd,E.B rothers,KNKudin,VNStaroverov,T.Keith,R.Kobayashi,J.Normand,K.Raghavachari,A.Rendell,JCBurant,SSIy engar,J.Tomasi,M.Cossi,N.Rega,JMMillam,M.Klene,JEKnox,JBCross,V.Bakken,J.Adamo,J.Jaramillo,R.Gomp erts,REStratmann,O.Yazyev,AJAustin,R.Cammi,J.Pomelli,JWOchterski,RLMartin,K.Morokuma,VGZakrzewski,GAVoth,P.Salvador,JJDannenberg,S.Dapprich,ADDaniels,O.Farkas,JBForesman,JVOrtizski,J.Condizski DJFox,Gaussian,Inc.,Wallingford CT,2010.)

[0045] In addition, the HOMO and LUMO can be calculated using the ionization potential and band gap. The HOMO can be estimated by measuring the ionization potential. The ionization potential is measured by depositing the compound to be measured on a substrate such as glass to prepare a deposited film. The deposited film can be measured with a measuring device such as AC-3. The band gap can be measured by dissolving the compound to be measured in a solvent such as toluene and applying excitation light. The band gap can be measured by measuring the absorption edge of the absorption spectrum where the solution absorbs the excitation light. Alternatively, the compound to be measured can be deposited on a substrate such as glass and applying excitation light to the deposited film. The band gap can be measured by measuring the absorption edge of the absorption spectrum where the deposited film absorbs the excitation light.

[0046] The LUMO can be calculated using the band gap and ionization potential. By adding the band gap to the ionization potential, the LUMO can be estimated.

[0047] The LUMO can also be estimated from the reduction potential. For example, the one-electron reduction potential is estimated using cyclic volmetry (CV) measurements. CV measurements are performed, for example, in a 0.1 M tetrabutylammonium perchlorate solution in DMF, with a Ag / Ag reference electrode. + The LUMO can be estimated by subtracting the difference between the reduction potential of the compound and that of ferrocene from the ionization potential of ferrocene, which is -4.8 eV.

[0048] In the present invention, the ionization potential and the band gap of the above-mentioned evaporated film are measured, the HOMO is estimated from the obtained ionization potential, and the LUMO is calculated by adding the band gap to the ionization potential.

[0049] The durability of an organic light-emitting device can be evaluated based on the time it takes for the luminance to deteriorate. By comparing the time it takes for the luminance to deteriorate from the initial luminance to a certain level, it can be expressed that the longer the time, the better the durability.

[0050] <Second Organic Light-Emitting Element> A second embodiment of the organic light-emitting element according to the present invention comprises, in this order, a first electrode, a first light-emitting unit, a charge generation section, a second light-emitting unit, and a second electrode, and the charge generation section includes at least one n-type charge generation layer.

[0051] (2-1) In the organic light-emitting device of the present embodiment, the n-type charge generation layer contains at least a first organic compound and a second organic compound, the first organic compound being a nitrogen-containing aromatic compound, and the second organic compound being represented by the following general formula [I] or [II]:

[0052] [ka]

[0053] In the above general formulas [I] and [II], X1 to X8 are carbon atoms having a substituent R or nitrogen atoms. Y represents a carbon atom having substituents R1 and R2, or an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom. When Y in the general formula [I] is a carbon atom having substituents R1 and R2, and in the general formula [II], at least one of X1 to X8 represents a nitrogen atom. R, R1, and R2 are selected from a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted amino group, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkoxy group, and a cyano group. In X1 to X8, when carbon atoms having the substituent R are adjacent to each other and the substituent R has a carbon atom, or when R1 and R2 each have a carbon atom, the adjacent substituents may form a ring.

[0054] In this embodiment, the n-type charge generation layer may contain an organic compound with high electron donor properties, such as a compound having an imidazoline skeleton, an alkali metal atom, or an alkaline earth metal atom, and preferably contains an alkali metal atom or an alkaline earth metal atom. When the second organic compound of the n-type charge generation layer is an organic compound represented by general formula [I] or [II], the alkali metal atom or alkaline earth metal atom contained in the n-type charge generation layer is prevented from diffusing into the light-emitting layer or the p-type charge generation layer, thereby preventing deterioration of the organic light-emitting device.

[0055] Examples of elements that exhibit electron injection properties include alkali metal atoms and alkaline earth metal atoms. When a layer containing these atoms and a phenanthroline derivative or a naphthyridine derivative is formed for the purpose of improving the electron injection properties, the durability of the organic light-emitting device may be reduced. Phenanthroline derivatives and naphthyridine derivatives are easy to form a chelate structure with alkali metal atoms or alkaline earth metal atoms, and therefore the electron injection properties are improved. On the other hand, when a voltage of a certain level or more is applied, alkali metal atoms and alkaline earth metal atoms move between these derivatives via the chelate structure and diffuse into the light-emitting layer. As a result, the alkali metal atoms or alkaline earth metal atoms act as a quencher of the light-emitting material, which may lead to a rapid decrease in luminance.

[0056] At the same time, the complex formed by the chelate structure of the above-mentioned derivative and alkali metal atoms and alkaline earth metal atoms transfers electrons to the anode side, and at the same time, positively charged alkali metal ions and alkaline earth metal ions are coordinated on the formed complex. These positive metal ion species diffuse into the p-type charge generation layer when voltage is applied. This causes a decrease in the function of the p-type charge generation layer and an increase in voltage.

[0057] On the other hand, compared to the above derivatives, the spatial distance between the two nitrogen atoms is far enough to form a chelate structure with an alkali metal atom and ion, or an alkaline earth metal atom and ion. Specifically, as shown below, the phenanthroline skeleton and naphthyridine skeleton are easy to form a chelate structure because the spatial distance of NN is close, that is, the bond angle is narrow. In contrast, the organic compounds represented by general formula [I] or [II] are difficult to form a chelate structure because the spatial distance of NN is far.

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] Therefore, by mixing an organic compound represented by general formula [I] or [II] as the second organic compound of the n-type charge generation layer, it is possible to reduce the diffusion of alkali metal atoms or alkaline earth metal atoms through the phenanthroline derivative to the light-emitting layer. In addition, when the charge generation section has a p-type charge generation layer, it is possible to suppress the diffusion of alkali metal ions or alkaline earth metal ions to the p-type charge generation layer. As a result, it is possible to provide an organic light-emitting device with excellent durability and suppressed voltage rise.

[0062] In this embodiment, the second organic compound is preferably represented by the following general formula [III].

[0063] [ka]

[0064] In the above general formula [III], R3 to R 10are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. R3 to R 10 When has a carbon atom, adjacent substituents may be joined to form a ring.

[0065] The second organic compound is preferably represented by the following general formula [IV].

[0066] [ka]

[0067] In the above general formula [IV], X1 to X4 are carbon atoms having a substituent R or nitrogen atoms, and at least one of them represents a nitrogen atom. R and R 11 ~R 16 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. R 11 ~R 16 When has a carbon atom, adjacent substituents may be joined to form a ring.

[0068] The second organic compound is preferably represented by the following general formula [V].

[0069] [ka]

[0070] In the above general formula [V], X1 to X4 are carbon atoms having a substituent R or nitrogen atoms, and at least one of them represents a nitrogen atom. R and R 17 ~R 20 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. R 17 ~R 20 When has a carbon atom, adjacent substituents may be joined to form a ring.

[0071] The second organic compound is preferably represented by the following general formula [VI].

[0072] [ka]

[0073] In the above general formula [VI], Y represents an oxygen atom, a sulfur atom, a selenium atom, or a tellurium atom. R 21 ~R 28 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. R 21 ~R 28 When has a carbon atom, adjacent substituents may be joined to form a ring.

[0074] In the above general formulas [I] to [VI], X1 to X8, R, R1 to R 28 The elements and substituents listed as the substituents will be explained.

[0075] In this specification, examples of halogen atoms include, but are not limited to, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, etc. Among these, fluorine atoms are preferred.

[0076] The alkyl group may be an alkyl group having 1 to 20 carbon atoms. Specific examples include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a tert-pentyl group, a neopentyl group, an n-hexyl group, an octyl group, a cyclohexyl group, a 1-adamantyl group, and a 2-adamantyl group. The alkyl group preferably has 1 to 10 carbon atoms, more preferably has 1 to 6 carbon atoms. Specifically, a methyl group or a tert-butyl group is preferred.

[0077] The alkoxy group may be an alkoxy group having 1 to 10 carbon atoms. Specific examples include, but are not limited to, a methoxy group, an ethoxy group, an n-propoxy group, an iso-propoxy group, an n-butoxy group, a tert-butoxy group, a 2-ethyl-octyloxy group, and a benzyloxy group. The alkoxy group preferably has 1 to 4 carbon atoms. Specifically, a methoxy group is preferred.

[0078] The aryl group may be an aryl group having 6 to 30 carbon atoms. Specific examples of the aryl group include, but are not limited to, a phenyl group, a naphthyl group, a phenanthryl group, an anthryl group, a fluorenyl group, a biphenylenyl group, an acenaphthylenyl group, a chrysenyl group, a pyrenyl group, a triphenylenyl group, a picenyl group, a fluoranthenyl group, a perylenyl group, a naphthacenyl group, a biphenyl group, a ter-phenyl group, and a biphenyl group.

[0079] The heterocyclic group may be a heterocyclic group having 3 to 27 carbon atoms. Specific examples include, but are not limited to, a thienyl group, a pyrrolyl group, a pyrazinyl group, a pyridyl group, an indolyl group, a quinolyl group, an isoquinolyl group, a naphthyridinyl group, an acridinyl group, a phenanthrolinyl group, a carbazolyl group, a benzo[a]carbazolyl group, a benzo[b]carbazolyl group, a benzo[c]carbazolyl group, a phenazinyl group, a phenoxazinyl group, a phenothiazinyl group, a benzothiophenyl group, a dibenzothiophenyl group, a benzofuranyl group, a dibenzofuranyl group, an oxazolyl group, and an oxadiazolyl group.

[0080] Specific examples of the silyl group include, but are not limited to, a trimethylsilyl group and a triphenylsilyl group.

[0081] Specific examples of the amino group include, but are not limited to, N-methylamino, N-ethylamino, N,N-dimethylamino, N,N-diethylamino, N-methyl-N-ethylamino, N-benzylamino, N-methyl-N-benzylamino, N,N-dibenzylamino, anilino, N,N-diphenylamino, N,N-dinaphthylamino, N,N-difluorenylamino, N-phenyl-N-tolylamino, N,N-ditolylamino, N-methyl-N-phenylamino, N,N-dianisolylamino, N-mesityl-N-phenylamino, N,N-dimesitylamino, N-phenyl-N-(4-tert-butylphenyl)amino, and N-phenyl-N-(4-trifluoromethylphenyl)amino. The amino group is preferably an N,N-dimethylamino or N,N-diphenylamino group.

[0082] The substituents which the above alkyl group, alkoxy group, aryl group, heterocyclic group, silyl group and amino group may further have are not particularly limited, and examples thereof include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, n-hexyl group and cyclohexyl group; alkoxy groups such as methoxy group, ethoxy group, isopropoxy group, n-butoxy group and tert-butoxy group; alkoxy group, N-methylamino group, N-ethylamino group, N,N-dimethylamino group, N,N-diethylamino group, N-methyl-N-ethylamino group, N-benzylamino group, N-methyl-N-benzylamino group, N,N-dibenzylamino group, anilino group, N,N-diphenylamino group, N,N-dinaphthylamino group, N,N-difluorenylamino group, N-phenyl-N-tolylamino group, N,N-ditolylamino group, N-methyl-N-phenylamino group, N,N-dianisolylamino group, N-mesityl-N-phenylamino group, substituted amino groups such as an N,N-dimesitylamino group, an N-phenyl-N-(4-tert-butylphenyl)amino group, or an N-phenyl-N-(4-trifluoromethylphenyl)amino group; aryl groups such as a phenyl group, a naphthyl group, a phenanthryl group, an anthryl group, a fluorenyl group, a biphenylenyl group, an acenaphthylenyl group, a chrysenyl group, a pyrenyl group, a triphenylenyl group, a picenyl group, a fluoranthenyl group, a perylenyl group, a naphthacenyl group, a biphenyl group, or a tert-phenyl group; thienyl group, and pyrrolyl group. , a pyrazinyl group, a pyridyl group, an indolyl group, a quinolyl group, an isoquinolyl group, a naphthyridinyl group, an acridinyl group, a phenanthrolinyl group, etc., a heteroaryl group such as a carbazolyl group, a benzo[a]carbazolyl group, a benzo[b]carbazolyl group, a benzo[c]carbazolyl group, a phenazinyl group, a phenoxazinyl group, a phenothiazinyl group, a benzothiophenyl group, a dibenzothiophenyl group, a benzofuranyl group, a dibenzofuranyl group, an oxazolyl group, an oxadiazolyl group, a cyano group, a trifluoromethyl group, etc.

[0083] Further, the second organic light-emitting device according to the present invention preferably has the following configurations (2-2) to (2-6). (2-2) An electron transport layer is provided adjacent to the n-type charge generating layer on the anode side of the n-type charge generating layer, and the electron transport layer contains an organic compound represented by general formula [I] or [II].

[0084] Table 2 below shows a comparison of the voltage and durability of the organic light-emitting devices of Examples 18 to 23 and Comparative Example 3 described below. In the table, the "No." of the electron transport layer, the first organic compound, and the second organic compound are the respective example compound numbers described below, and the ΔHOMO and ΔLUMO are as follows. The voltage ratio and durability ratio are relative values ​​when the voltage and durability of Comparative Example 1 are set to 1.0, respectively. ΔHOMO = HOMO(H2) - HOMO(H1) ΔLUMO=|LUMO(H1)-LUMO(H2)|

[0085] [Table 2]

[0086] It can be seen that the lifespan is further improved by changing the material used in the electron transport layer to an organic compound represented by general formula [I] or [II]. This is because, by not only mixing the organic compound represented by general formula [I] or [II] in the n-type charge generating layer but also using it in the electron transport layer, the diffusion of alkali metal atoms into the light emitting layer is suppressed, and as a result, the quenching of the light emitting material by the alkali metal atoms is suppressed, improving the durability of the organic light emitting device.

[0087] (2-3) The second organic compound in the n-type charge generating layer and the organic compound represented by the general formula [I] or [II] used in the electron transport layer adjacent to the anode side of the n-type charge generating layer are the same. By using the same compound for the second organic compound in the n-type charge generation layer and the electron transport layer adjacent to the anode side of the n-type charge generation layer, the injection barrier from the n-type charge generation layer to the electron transport layer can be eliminated, making it easier to inject and transport electrons into the electron transport layer.

[0088] (2-4) The first organic compound and the second organic compound of the n-type charge generating layer satisfy the relationship of the following formula [1]. |LUMO(H1)-LUMO(H2)|≦0.1ev [1] The above formula [1] is the same as the formula [1] described in the first organic light-emitting device, and for the same reason as in the first organic light-emitting device, satisfying the relationship of the above formula [1] can improve the electron mobility in the n-type charge generating layer, thereby further reducing the voltage of the organic light-emitting device according to this embodiment.

[0089] (2-5) The first organic compound and the second organic compound of the n-type charge generating layer satisfy the relationship of formula [2-1]. HOMO(H2)-HOMO(H1)>0.0eV [2-1] As described above, in the configuration of the present invention, there are cases where holes are easily leaked from the light-emitting layer. That is, instead of trapping holes in the light-emitting layer, it is preferable to trap holes in other layers, and in particular, the first organic compound and the second organic compound of the n-type charge generation layer satisfy the relationship of formula [2-1], so that holes can be trapped in the n-type charge generation layer. More specifically, the compound represented by general formula [I] or [II] traps holes in the n-type charge generation layer. This makes it possible to suppress the deterioration of the first organic compound, which is more unstable to holes due to interaction with alkali metal atoms and alkaline earth metal atoms, caused by holes. As a result, it is possible to suppress the deterioration of the entire n-type charge generation layer, and the deterioration of the luminance of the organic light-emitting device can be suppressed. In addition, since the n-type charge generation layer has a hole trap configuration, it becomes difficult for holes to reach the p-type charge generation layer, so that the deterioration of the organic light-emitting device can be suppressed. The above formula [2-1] is the same as the formula [2-1] described in the first organic light-emitting device.

[0090] Furthermore, in this embodiment, by satisfying the relationship of the following formula [2-2], the hole trapping ability of the second organic compound is increased, and thus durability is further improved. HOMO(H2)-HOMO(H1)≧0.2eV [2-2] The above formula [2-2] is the same as the formula [2-2] described in the first organic light-emitting device.

[0091] (2-6) A first light-emitting unit has a first light-emitting layer, the first light-emitting layer contains at least a third organic compound and a first light-emitting compound, and the third organic compound and the first light-emitting compound satisfy the relationship represented by formula [3]. LUMO(H3)-LUMO(D1)>HOMO(D1)-HOMO(H3) [3] The above formula [3] is similar to the formula [3] described in the first organic light-emitting element. For the same reason as in the first organic light-emitting element, by satisfying the relationship of the above formula [3], the first light-emitting layer becomes an electron trap type, deterioration due to holes is suppressed, and durability of the organic light-emitting element is improved.

[0092] Similarly to the first organic light-emitting element, the first light-emitting layer preferably satisfies the relationship represented by the following formula [4] in order to exhibit a sufficient electron trapping property. LUMO(H3)-LUMO(D1)≧0.1 eV [4]

[0093] Next, examples of compounds that can be used in the organic light-emitting device of the present invention will be given. Examples of the first organic compound of the n-type charge generating layer include, but are not limited to, phenanthroline derivatives and naphthyridine derivatives represented by the following ET1 to ET14.

[0094] [ka]

[0095] Examples of the second organic compound of the n-type charge generating layer include, but are not limited to, the following compounds represented by A1 to A12. These compounds are substituted with a fused polycyclic group having three or more rings containing a fluorene skeleton, and are characterized by a high HOMO, hole trapping properties, and fast electron mobility.

[0096] [ka]

[0097] Examples of the second organic compound of the n-type charge generating layer include, but are not limited to, the following compound groups represented by B1 to B8. These compound groups are compounds having a fluorene skeleton and at least one phenylene group substituted therewith, and tend to have a lower HOMO than compound group A, but have the characteristic of suppressing crystallization and providing excellent filmability.

[0098] [ka]

[0099] Examples of the second organic compound of the n-type charge generating layer include, but are not limited to, the following compounds represented by C1 to B8. These compounds are substituted with a fluorene skeleton and at least one fused polycyclic group having four or more rings, and tend to have a lower HOMO than compound A, but are characterized by a high glass transition temperature and excellent heat resistance.

[0100] [ka]

[0101] Examples of the second organic compound of the n-type charge generating layer include, but are not limited to, the following compounds represented by D1 to D44. These compounds are condensed polycyclic aromatic hydrocarbon compounds having a chrysene skeleton at the center of the molecular structure. Since they have a chrysene skeleton in their molecular structure, they have a wide band gap and excellent charge transport properties.

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] [ka]

[0107] Examples of the second organic compound of the n-type charge generating layer include, but are not limited to, the following compound groups represented by E1 to E22. These compounds are condensed polycyclic aromatic hydrocarbon compounds having a triphenylene skeleton in their molecular structure, and because they have a triphenylene skeleton in their molecular structure, they are compounds that have high planarity and are easy to stack intermolecularly. As a result, they are organic compounds with excellent charge mobility, and can form organic light-emitting devices that operate at a lower voltage.

[0108] [ka]

[0109] [ka]

[0110] Examples of the second organic compound of the n-type charge generating layer include, but are not limited to, the following compound groups represented by F1 to F11. These compounds are condensed polycyclic aromatic hydrocarbon compounds having an anthracene skeleton in their molecular structure. Since they have an anthracene skeleton in their molecular structure, they have a narrow band gap and a small lowest excited triplet energy. In addition, they are organic compounds with a high HOMO energy level (close to the vacuum level) and excellent hole trapping properties.

[0111] [ka]

[0112] In addition, examples of the second organic compound of the n-type charge generating layer of the present invention include, but are not limited to, the following compound groups represented by G1 to G10. These compound groups are condensed polycyclic aromatic hydrocarbon compounds having a divalent naphthalene skeleton in the molecular structure. The divalent naphthalene skeleton has a condensed polycyclic aromatic hydrocarbon substituent with high planarity, which results in an organic compound with excellent charge mobility. As a result, an organic light-emitting device with a lower voltage can be constructed. By introducing different substituents into the naphthalene skeleton, an organic compound with asymmetry and planarity is obtained. Such an organic compound has a high glass transition temperature and excellent charge mobility. Therefore, it is possible to construct an organic light-emitting device that is excellent in durability and requires a lower voltage.

[0113] [ka]

[0114] Examples of the second organic compound of the n-type charge generating layer of the present invention include, but are not limited to, the following compound groups represented by H1 to H15. These compound groups are condensed polycyclic aromatic hydrocarbon compounds having a perylene skeleton in their molecular structure. Since the compound groups have a perylene skeleton in their molecular structure, the exemplary compounds belonging to group H are a compound group having a narrow band gap and a small minimum excited triplet energy. Furthermore, the exemplary compounds belonging to group H are a compound group having a high HOMO energy level, and are therefore organic compounds with excellent hole trapping properties.

[0115] [ka]

[0116] [ka]

[0117] Specific examples of the organic compound represented by the general formula [I] or [II] are shown below, but the present invention is not limited thereto.

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] [ka]

[0123] [ka]

[0124] [ka]

[0125] [ka]

[0126] [ka]

[0127] The exemplary compounds belonging to the AA group are those represented by the general formula [III], where X4 and X5 are nitrogen atoms and Y is a carbon atom having the substituents R1 and R2 in the general formula [I]. The compounds in this group are characterized by a low HOMO and fast electron mobility. The exemplified compounds belonging to the BB group are those represented by the general formula [IV], where X4 or X5 is a nitrogen atom and Y is a carbon atom having the substituents R1 and R2 in the general formula [I]. The compounds belonging to this group are characterized by a higher HOMO and faster electron mobility than the compounds belonging to the AA group. The exemplary compounds belonging to the CC group are compounds represented by the general formula [II] in which at least one of X1 to X8 represents a nitrogen atom, and are a group of compounds represented by the general formula [V]. The compounds belonging to this group have a low HOMO, but are characterized by suppressed crystallization, excellent film-forming properties, and fast electron mobility. The exemplified compounds belonging to the DD group are those represented by the general formula [VI], where X4 and X5 are nitrogen atoms and Y is an oxygen atom or a sulfur atom in the general formula [I]. The compounds belonging to this group are characterized by a high glass transition temperature, excellent heat resistance, and fast electron mobility.

[0128] <Other ingredients> In the organic light-emitting device according to this embodiment, conventionally known low-molecular-weight and high-molecular-weight hole-injecting or hole-transporting compounds, host compounds, light-emitting compounds, electron-injecting or electron-transporting compounds, etc. may also be used as necessary. Examples of these compounds are given below.

[0129] As the hole injection transport material, a material having high hole mobility is preferable so that the injection of holes from the anode can be easily performed and the injected holes can be transported to the light emitting layer. In addition, a material having a high glass transition temperature is preferable so as to suppress deterioration of the film quality such as crystallization in the organic light emitting device. Examples of low molecular weight and high molecular weight materials having hole injection transport performance include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. Furthermore, the above hole injection transport material is also preferably used in the electron blocking layer or p-type charge generating layer. Specific examples of compounds used as the hole injection transport material are shown below, but are not limited to these.

[0130] [ka]

[0131] Examples of luminescent materials mainly involved in luminescence function include condensed ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives. Specific examples of compounds used as luminescent materials are shown below, but are not limited to these.

[0132] [ka]

[0133] [ka]

[0134] Examples of the third organic compound (host compound) and fourth organic compound (assist compound) contained in the first light-emitting layer, and the fifth organic compound (host compound) and sixth organic compound (assist compound) contained in the second light-emitting layer include, but are not limited to, aromatic hydrocarbon compounds or derivatives thereof, carbazole derivatives, azine derivatives, xanthone derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organic aluminum complexes such as tris(8-quinolinolato)aluminum, and organic beryllium complexes. Specific examples are shown below.

[0135] [ka]

[0136] The electron transporting material can be arbitrarily selected from those capable of transporting electrons injected from the cathode to the light-emitting layer, and is selected in consideration of the balance with the hole mobility of the hole transporting material. Examples of materials having electron transporting properties include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, naphthyridine derivatives, organic aluminum complexes, and condensed ring compounds (e.g., fluorene derivatives, naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.). Furthermore, the above electron transporting materials are also preferably used in the hole blocking layer. Specific examples of compounds used as electron transporting materials are shown below, but are of course not limited to these. Specific examples are shown below.

[0137] [ka]

[0138] Of the above example compounds, compounds ET1 to 21, ET24 to 26, and ET29 to 30 can be suitably used as the first organic compound of the n-type charge generating layer.

[0139] The electron injection material can be selected from those that can easily inject electrons from the cathode, and is selected in consideration of the balance with hole injection properties. Organic compounds include n-type dopants and reducing dopants. For example, compounds containing alkali metals such as lithium fluoride, lithium complexes such as lithium quinolinol, benzimidazolidine derivatives, imidazolidine derivatives, fulvalene derivatives, and acridine derivatives can be mentioned. They can also be used in combination with the above electron transport materials.

[0140] <Configuration of organic light-emitting element> An organic light-emitting element is usually provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, a microlens, etc. may be provided on the second electrode. When a color filter is provided, a planarizing layer may be provided between the protective layer. The planarizing layer may be made of acrylic resin, etc. The same applies when a planarizing layer is provided between the color filter and the microlens. Preferred configurations of the organic light-emitting element of the present invention and of a device having the organic light-emitting element will be described below.

[0141] [substrate] The organic light-emitting element of the present invention may be formed on a substrate, and examples of the substrate include quartz, glass, silicon wafer, resin, and metal. In addition, the substrate may be provided with switching elements such as transistors and wiring, and an insulating layer may be provided thereon. As the insulating layer, any material can be used as long as it can form a contact hole so that wiring can be formed between the first electrode and the insulating layer, and can ensure insulation from wiring that is not connected. For example, resins such as polyimide, silicon oxide, silicon nitride, etc. can be used.

[0142] [electrode] An organic light-emitting element has a pair of electrodes, and when an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode. In the present invention, either the anode or the cathode may be the first electrode (substrate side). Usually, as illustrated in FIG. 1, the first electrode 200 on the substrate 1 side is the anode, but this is not limited thereto.

[0143] The material constituting the anode should have as large a work function as possible. For example, metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, etc., mixtures containing these metals, alloys combining these metals, metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide can be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used. These electrode materials may be used alone or in combination of two or more kinds. The anode may be composed of one layer or multiple layers.

[0144] When used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates thereof can be used. The above materials can also function as a reflective film without serving as an electrode. When used as a transparent electrode, a transparent conductive layer of oxide such as indium tin oxide (ITO) or indium zinc oxide can be used, but is not limited to these. Photolithography technology can be used to form the electrode.

[0145] On the other hand, the material for the cathode should have a small work function. Examples of the material include alkali metals such as lithium, alkaline earth metals such as calcium, aluminum, titanium, manganese, silver, lead, chromium, and other metals or mixtures containing these metals. Alternatively, alloys combining these metals can be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, zinc-silver, and the like can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials may be used alone or in combination of two or more types. The cathode may have a single layer structure or a multi-layer structure. Among these, it is preferable to use silver, and it is even more preferable to use a silver alloy to reduce the aggregation of silver. As long as the aggregation of silver can be reduced, the ratio of the alloy is not important. For example, the ratio of silver to other metals may be 1:1, 3:1, and the like.

[0146] The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but it is more preferable to use a direct current or alternating current sputtering method, etc., since the film coverage is good and the resistance can be easily reduced.

[0147] [Organic compound layer] 1, the first light-emitting unit 300, the charge generating section 400, and the second light-emitting unit 500 are usually called organic compound layers, but may include a layer made of an inorganic compound. In addition, an insulating layer, an adhesive layer, or an interference layer may be provided at the interface between the first electrode 200 and the first light-emitting unit 300 and the interface between the second electrode 600 and the second light-emitting unit 500.

[0148] In a configuration in which a plurality of organic light-emitting elements are arranged, the organic compound layer may be formed as a common layer for the plurality of organic light-emitting elements. The common layer is disposed across the plurality of organic light-emitting elements, and can be formed by applying a coating method such as spin coating or a vapor deposition method to the entire surface of the substrate.

[0149] The organic compound layer constituting the organic light-emitting device of the present invention can be formed by dry processes such as vacuum deposition, ionization deposition, sputtering, plasma, etc. Alternatively, instead of the dry process, a wet process can be used in which a layer is formed by dissolving the compound in an appropriate solvent and applying a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

[0150] Here, when the layer is formed by a vacuum deposition method or a solution coating method, crystallization is unlikely to occur and the layer has excellent stability over time. When the layer is formed by a coating method, the layer can be formed by combining with a suitable binder resin. Examples of the binder resin include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin. These binder resins may be used alone or in combination as homopolymers or copolymers, and may further include known additives such as plasticizers, antioxidants, and ultraviolet absorbers, if necessary.

[0151] [Protective layer] A protective layer may be provided on the second electrode. For example, by bonding glass provided with a moisture absorbent on the second electrode, it is possible to reduce the intrusion of water and the like into the organic compound layer and reduce the occurrence of display defects. In another embodiment, a passivation film such as silicon nitride may be provided on the second electrode to reduce the intrusion of water and the like into the organic compound layer. For example, after forming the second electrode, the second electrode may be transported to another chamber without breaking the vacuum, and a silicon nitride film having a thickness of 2 μm may be formed by a CVD method to serve as a protective layer. A protective layer may be provided using an atomic deposition method (ALD method) after the film formation by the CVD method. The material of the film by the ALD method is not limited, and may be silicon nitride, silicon oxide, aluminum oxide, etc. Silicon nitride may be further formed by a CVD method on the film formed by the ALD method. The film formed by the ALD method may have a smaller thickness than the film formed by the CVD method. Specifically, it may be 50% or less, or even 10% or less.

[0152] [Color Filter] A color filter may be provided on the protective layer. For example, a color filter taking into consideration the size of the organic light-emitting element may be provided on another substrate and then bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer described above using a photolithography technique. The color filter may be made of a polymer.

[0153] [Planarization layer] A planarization layer may be provided between the color filter and the protective layer. The planarization layer is provided for the purpose of reducing the unevenness of the layer below. It may also be called a material resin layer without limiting the purpose. The planarization layer may be composed of an organic compound, and may be a low molecular weight or a high molecular weight, but is preferably a high molecular weight. The planarization layer may be provided above and below the color filter, and may be made of the same or different materials.Specific examples of the materials include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.

[0154] [Microlens] The organic light-emitting element or the organic light-emitting device having the organic light-emitting element may have an optical member such as a microlens on the light-emitting side. The microlens may be made of acrylic resin, epoxy resin, or the like. The microlens may be intended to increase the amount of light extracted from the organic light-emitting element or the organic light-emitting device, or to control the direction of the extracted light. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, among the tangents to the hemisphere, there is a tangent that is parallel to the insulating layer, and the tangent and the hemisphere are the vertices of the microlens. The vertex of the microlens can be determined in the same manner in any cross-sectional view. That is, among the tangents to the semicircle of the microlens in the cross-sectional view, there is a tangent that is parallel to the insulating layer, and the tangent and the semicircle are the vertices of the microlens. It is also possible to define the midpoint of the microlens. In the cross section of the microlens, a line segment is imaginary from a point where an arc shape ends to a point where another arc shape ends, and the midpoint of the line segment can be called the midpoint of the microlens. The cross section for determining the vertex and midpoint may be a cross section perpendicular to the insulating layer.

[0155] [Opposite substrate] A counter substrate may be provided on the planarization layer. The counter substrate is called a counter substrate because it is provided at a position corresponding to the aforementioned substrate. The constituent material of the counter substrate may be the same as that of the aforementioned substrate (substrate on the first electrode side). When the aforementioned substrate is the first substrate, the counter substrate may be the second substrate.

[0156] [Pixel circuit] An organic light-emitting device having an organic light-emitting element may have a pixel circuit connected to the organic light-emitting element. The pixel circuit may be an active matrix type that controls the emission of the first light-emitting element and the second light-emitting element independently. The active matrix type circuit may be voltage programming or current programming. The drive circuit has a pixel circuit for each pixel. The pixel circuit may have a light-emitting element, a transistor that controls the emission luminance of the light-emitting element, a transistor that controls the emission timing, a capacitance that holds the gate voltage of the transistor that controls the emission luminance, and a transistor for connecting to GND without going through the light-emitting element.

[0157] The light emitting device has a display region and a peripheral region arranged around the display region. The display region has a pixel circuit, and the peripheral region has a display control circuit. The mobility of a transistor constituting the pixel circuit may be smaller than the mobility of a transistor constituting the display control circuit. The slope of the current-voltage characteristic of the transistor constituting the pixel circuit may be smaller than the slope of the current-voltage characteristic of the transistor constituting the display control circuit. The slope of the current-voltage characteristic can be measured by the so-called Vg-Ig characteristic. The transistor constituting the pixel circuit is a transistor connected to a light emitting element, such as a first light emitting element.

[0158] [Pixels] An organic light-emitting device having an organic light-emitting element may have a plurality of pixels, each of which has sub-pixels that emit different colors, and each of the sub-pixels may have, for example, RGB light-emitting colors. A pixel has an area that emits light, also called a pixel aperture. The pixel aperture may be 15 μm or less, or 5 μm or more. More specifically, it may be 11 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc. The distance between subpixels may be 10 μm or less, more specifically, it may be 8 μm, 7.4 μm, 6.4 μm.

[0159] The pixels may have a known arrangement in plan view. For example, they may have a stripe arrangement, a delta arrangement, a pentile arrangement, or a Bayer arrangement. The shape of the subpixels in plan view may be any known shape. For example, they may be a rectangle, a quadrangle such as a diamond, or a hexagon. Of course, if the shape is not an exact figure but is close to a rectangle, it is included in the rectangle. The shape of the subpixels and the pixel arrangement may be used in combination.

[0160] <Applications of organic light-emitting devices> The organic light-emitting element of the present invention can be used as a component of a display device or a lighting device, and can also be used as an exposure light source for an electrophotographic image forming apparatus, a backlight for a liquid crystal display device, a light-emitting device having a white light source and a color filter, etc.

[0161] The display device may be an image information processing device having an image input unit that inputs image information from an area CCD, a linear CCD, a memory card, etc., an information processing unit that processes the input information, and displays the input image on a display unit. The display device may have a plurality of pixels, at least one of which has the organic light-emitting element of this embodiment and a transistor connected to the organic light-emitting element.

[0162] The display unit of the imaging device or inkjet printer may have a touch panel function. The driving method of the touch panel function may be an infrared type, a capacitance type, a resistive film type, or an electromagnetic induction type, and is not particularly limited. The display device may be used in the display unit of a multifunction printer.

[0163] Next, the display device according to the present embodiment will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing an example of a display device having an organic light-emitting element of the present invention and a transistor connected to this organic light-emitting element. FIG. 2(a) is an example of a pixel that is a component of the display device according to this embodiment. The pixel has a subpixel 20. The subpixels are divided into 20R, 20G, and 20B according to their light emission. The emitted light color may be distinguished by the wavelength emitted from the light-emitting layer, or the light emitted from the subpixel may be selectively transmitted or color-converted by a color filter or the like. Each subpixel has a first electrode 12 that is a reflective electrode on an interlayer insulating layer 11, an insulating layer 13 that covers the edge of the first electrode 12, an organic compound layer 14 that covers the first electrode 12 and the insulating layer 13, a second electrode 15, a protective layer 16, and a color filter 17. The first electrode 12, the organic compound layer 14, and the second electrode 15 constitute an organic light-emitting element 18 according to this embodiment.

[0164] A transistor and a capacitor may be disposed below or inside the interlayer insulating layer 11. The transistor and the first electrode 12 may be electrically connected via a contact hole (not shown) or the like. The insulating layer 13 is also called a bank or a pixel separation film. It covers the ends of the first electrodes 12 and is disposed so as to surround the first electrodes 12. The portion where the insulating layer 13 is not disposed contacts the organic compound layer 14 and becomes a light-emitting region. The second electrode 15 may be a transparent electrode, a reflective electrode, or a semi-transparent electrode. The protective layer 16 reduces the penetration of moisture into the organic compound layer 14. Although the protective layer 16 is illustrated as being a single layer, it may be a multi-layer. Each layer may be an inorganic compound layer and an organic compound layer.

[0165] The color filters 17 are divided into 17R, 17G, and 17B according to their colors. The color filters may be formed on a planarization film (not shown). A resin protective layer (not shown) may be provided on the color filters. The color filters 17 may be formed on a protective layer 16. Alternatively, the color filters 17 may be provided on an opposing substrate such as a glass substrate and then bonded to each other.

[0166] 2(b) has an organic light-emitting element 36 and a TFT 28 as an example of a transistor. Specifically, a substrate 21 such as glass or silicon is provided with an insulating layer 22 on the upper part thereof, and a TFT 28 having a gate electrode 23, a gate insulating film 24, a semiconductor layer 25, a drain electrode 26, and a source electrode 27 is disposed on the insulating layer 22. An insulating film 29 is provided on the upper part of the TFT 28, and an anode 31 constituting the organic light-emitting element 36 and the source electrode 27 are connected via a contact hole 30 provided in the insulating film 29.

[0167] The electrical connection between the electrodes (anode 31, cathode 33) included in the organic light-emitting element 36 and the electrodes (source electrode 27, drain electrode 26) included in the TFT 28 is not limited to the embodiment shown in Fig. 2(b). In other words, it is sufficient that either one of the anode 31 or the cathode 33 is electrically connected to either one of the source electrode 27 or the drain electrode 26. TFT 28 refers to a thin film transistor. On the cathode 33, a first protective layer 34 and a second protective layer 35 are provided for reducing deterioration of the organic light-emitting element.

[0168] The organic light emitting element 36 according to this embodiment has its light emission luminance controlled by the TFT 28, and by providing a plurality of organic light emitting elements 36 on a surface, an image can be displayed based on the respective light emission luminances.

[0169] In the display device of FIG. 2(b), transistors are used as switching elements, but other switching elements may be used instead. 2(b) is not limited to a TFT having an active layer on an insulating surface of a substrate, but may be a transistor using a single crystal silicon wafer. The active layer may be made of non-single crystal silicon such as amorphous silicon or microcrystalline silicon, or a non-single crystal oxide semiconductor such as indium zinc oxide or indium gallium zinc oxide.

[0170] Alternatively, the transistor may be made of low-temperature polysilicon, or an active matrix driver may be formed on a substrate such as a Si substrate. On the substrate can also be said to be inside the substrate. Whether to provide a transistor inside the substrate or to use a TFT is selected depending on the size of the display unit. For example, if the size is about 0.5 inches, it is preferable to provide an organic light-emitting element on a Si substrate. Here, forming inside the substrate means that the substrate itself, such as a Si substrate, is processed to produce a transistor. In other words, having a transistor inside the substrate can be seen as the substrate and the transistor being formed integrally.

[0171] 3 is a schematic diagram showing an example of a display device according to the present invention. The display device 1000 has a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. Flexible printed circuits FPC1002 and 1004 are connected to the touch panel 1003 and the display panel 1005. A transistor is printed on the circuit board 1007. The battery 1008 may not be provided if the display device is not a portable device, and may be provided in a different position even if the display device is a portable device.

[0172] The display device according to the present embodiment may have color filters having red, green, and blue colors, and the red, green, and blue colors may be arranged in a delta arrangement in the color filters.

[0173] The display device according to the present embodiment is used in a display unit of a mobile terminal. In this case, the display device may have both a display function and an operation function. Examples of the mobile terminal include mobile phones such as smartphones, tablets, and head-mounted displays.

[0174] The display device according to the present embodiment is used in a display unit of an imaging device having an optical unit with a plurality of lenses and an imaging element that receives light that has passed through the optical unit. The imaging device may have a display unit that displays information acquired by the imaging element. The display unit may be a display unit exposed to the outside of the imaging device, or may be a display unit disposed within a viewfinder. The imaging device may be a digital camera or a digital video camera.

[0175] 4(a) is a schematic diagram showing an example of an imaging device according to the present invention. The imaging device 1100 has a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 has a display device according to this embodiment. In this case, the display device may display not only an image to be captured, but also environmental information, imaging instructions, and the like. The environmental information may include the intensity of external light, the direction of external light, the moving speed of the subject, the possibility that the subject will be blocked by an obstruction, and the like.

[0176] Since the timing suitable for imaging is short, it is better to display information as soon as possible. Therefore, it is preferable to use a display device using the organic light-emitting element of the present invention. This is because the organic light-emitting element has a fast response speed. A display device using an organic light-emitting element can be used more preferably than a liquid crystal display device, which requires a high display speed.

[0177] The imaging device 1100 has an optical section (not shown). The optical section has a plurality of lenses, which form an image on an imaging element housed in a housing 1104. The focus of the plurality of lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically. The imaging device may be called a photoelectric conversion device. The photoelectric conversion device can include an imaging method that does not capture images sequentially, but detects the difference from the previous image, cuts out an image from an image that is always recorded, and the like.

[0178] FIG. 4(b) is a schematic diagram showing an example of an electronic device according to the present invention. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type reaction unit. The operation unit may be a biometric recognition unit that recognizes a fingerprint and performs unlocking or the like. An electronic device having a communication unit can also be called a communication device. The electronic device may further have a camera function by including a lens and an image sensor. An image captured by the camera function is displayed on the display unit. Examples of the electronic device include a smartphone and a notebook computer.

[0179] FIG. 5 is a schematic diagram showing an example of a display device according to the present invention. FIG. 5(a) shows a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. The display unit 1302 uses a light-emitting device according to the present invention. The display device 1300 has the frame 1301 and a base 1303 that supports the display unit 1302. The base 1303 is not limited to the form shown in FIG. 5(a). The lower side of the frame 1301 may also serve as the base. The frame 1301 and the display unit 1302 may be curved. The radius of curvature may be 5000 mm or more and 6000 mm or less.

[0180] FIG. 5(b) is a schematic diagram showing another example of a display device according to the present invention. The display device 1310 in FIG. 5(b) is configured to be bendable, and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 have a light-emitting device according to the present invention. The first display unit 1311 and the second display unit 1312 may be a single display unit without a joint. The first display unit 1311 and the second display unit 1312 can be separated at the bending point. The first display unit 1311 and the second display unit 1312 may display different images, or the first and second display units may display one image.

[0181] FIG. 6(a) is a schematic diagram showing an example of a lighting device according to the present invention. The lighting device 1400 has a housing 1401, a light source 1402, a circuit board 1403, an optical filter 1404, and a light diffusion unit 1405. The light source 1402 has an organic light-emitting element according to the present invention. The optical filter 1404 may be a filter that improves the color rendering of the light source. The light diffusion unit 1405 can effectively diffuse the light of the light source 1402, such as for lighting up, and deliver the light to a wide range. The optical filter 1404 and the light diffusion unit 1405 may be provided on the light emission side of the lighting. If necessary, a cover may be provided on the outermost part.

[0182] The lighting device is, for example, a device that illuminates a room. The lighting device may emit white light, natural white light, or any other color from blue to red. It may have a dimming circuit that adjusts the light intensity. The lighting device has the organic light-emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit that converts AC voltage into DC voltage. Moreover, white has a color temperature of 4200K, and natural white has a color temperature of 5000K. The lighting device may have a color filter. The lighting device according to the present invention may further include a heat dissipation section that dissipates heat from within the device to the outside, and examples of the heat dissipation section include metals with high specific heat, liquid silicone, and the like.

[0183] Fig. 6(b) is a schematic diagram of an automobile, which is an example of a moving body according to the present invention. The automobile has tail lamps, which are an example of a lamp. The automobile 1500 has tail lamps 1501, and may be configured to turn on the tail lamps when braking or the like is performed. A tail lamp 1501 has an organic light-emitting element according to the present invention. The tail lamp may have a protective member for protecting the organic light-emitting element. The protective member may be made of any material as long as it has a certain degree of strength and is transparent, but it is preferable that the protective member is made of polycarbonate or the like. A furandicarboxylic acid derivative, an acrylonitrile derivative, or the like may be mixed with the polycarbonate.

[0184] The automobile 1500 may have a body 1503 and a window 1502 attached thereto. The window may be a transparent display as long as it is not a window for checking the front and rear of the automobile. The transparent display may have an organic light-emitting element according to the present invention. In this case, the constituent materials of the electrodes and the like of the organic light-emitting element are made of transparent members.

[0185] The moving body according to the present invention may be a ship, an aircraft, a drone, or the like. The moving body has a body and a lamp provided on the body. The lamp emits light to indicate the position of the body. The lamp has the organic light-emitting element according to the present invention.

[0186] An application example of the display device of each of the above-mentioned embodiments will be described with reference to Fig. 7. The display device can be applied to a system that can be worn as a wearable device such as smart glasses, HMD, and smart contacts. An image capturing and display device used in such an application example has an image capturing device capable of photoelectrically converting visible light, and a display device capable of emitting visible light.

[0187] 7(a) illustrates glasses 1600 (smart glasses) according to one application example. An imaging device 1602 such as a CMOS sensor or a SPAD is provided on the front side of a lens 1601 of the glasses 1600. In addition, a display device according to each of the above-mentioned embodiments is provided on the back side of the lens 1601. The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the image capture device 1602 and the display device according to each embodiment. The control device 1603 also controls the operations of the image capture device 1602 and the display device. The lens 1601 is formed with an optical system for focusing light on the image capture device 1602.

[0188] FIG. 7(b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612, and the control device 1612 is equipped with an imaging device corresponding to the imaging device 1602 in FIG. 7(a) and a display device. The lens 1611 is formed with an imaging device in the control device 1612 and an optical system for projecting light emitted from the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power source that supplies power to the imaging device and the display device, and controls the operation of the imaging device and the display device. The control device 1612 may have a line of sight detection unit that detects the line of sight of the wearer. Infrared light may be used for detecting the line of sight. The infrared light emission unit emits infrared light toward the eyeball of a user gazing at a display image. An imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. By having a reduction means for reducing light from the infrared light emission unit to the display unit in a planar view, deterioration of image quality is reduced.

[0189] The user's gaze with respect to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be applied to gaze detection using an image of the eyeball. As an example, a gaze detection method based on a Purkinje image produced by reflection of irradiated light on the cornea can be used. More specifically, a gaze detection process based on a pupil-corneal reflex method is performed. Using the pupil-corneal reflex method, a gaze vector representing the direction (rotation angle) of the eyeball is calculated based on the image of the pupil and the Purkinje image contained in the image of the eyeball, thereby detecting the user's gaze.

[0190] The display device according to the present invention may have an imaging device having a light receiving element, and may control the display image of the display device based on the line-of-sight information of the user from the imaging device. Specifically, the display device determines a first field of view area to which the user gazes and a second field of view area other than the first field of view area based on the line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be received from an external control device. In the display area of ​​the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0191] The display area includes a first display area and a second display area different from the first display area, and an area having a high priority is determined from the first display area and the second display area based on line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be determined by an external control device and received. The resolution of the area having a high priority may be controlled to be higher than the resolution of areas other than the area having a high priority. In other words, the resolution of an area having a relatively low priority may be lowered.

[0192] AI may be used to determine the first field of view area and areas with high priority. The AI ​​may be a model configured to estimate the angle of the line of sight and the distance to an object at the end of the line of sight from the image of the eyeball, using as teacher data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI ​​program may be included in the display device, the imaging device, or an external device. If included in the external device, it is transmitted to the display device via communication. When display control is performed based on visual recognition detection, the present invention is preferably applicable to smart glasses that further include an imaging device for capturing images of the outside world. The smart glasses can display captured outside information in real time.

[0193] FIG. 8(a) is a schematic diagram showing an example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1700 is an electrophotographic image forming apparatus, and includes a photoconductor 1707, an exposure light source 1708, a charging unit 1710, a developing unit 1711, a transfer unit 1712, a transport roller 1713, and a fixing unit 1715. Light 1709 is irradiated from the exposure light source 1708, and an electrostatic latent image is formed on the surface of the photoconductor 1707. The exposure light source 1708 includes an organic light emitting element according to the present invention. The developing unit 1711 includes a toner and the like. The charging unit 1710 charges the photoconductor 1707. The transfer unit 1712 transfers the developed image to a recording medium 1714. The transport roller 1713 transports the recording medium 1714. The recording medium 1714 is, for example, paper. The fixing unit 1715 fixes the image formed on the recording medium 1714.

[0194] 8(b) and 8(c) are diagrams showing the exposure light source 1708, and are schematic diagrams showing a state in which a plurality of light-emitting units 1726 are arranged on a long substrate. An arrow 1727 is a direction parallel to the axis of the photoconductor, and represents the column direction in which the organic light-emitting elements are arranged. This column direction is the same as the axis direction about which the photoconductor 1707 rotates. This direction can also be called the long axis direction of the photoconductor 1707. FIG. 8(b) shows a form in which the light-emitting units 1726 are arranged along the long axis direction of the photoconductor 1707. The light-emitting units 1726 have organic light-emitting elements according to the present invention. FIG. 8(c) shows a form different from that of FIG. 8(b), in which the light-emitting units 1726 are alternately arranged in the column direction in each of the first and second columns. The first and second columns are arranged at different positions in the row direction. In the first column, a plurality of light-emitting units 1726 are arranged at intervals. The second column has light emitting units 1726 at positions corresponding to the intervals between the light emitting units 1726 in the first column. That is, the light emitting units 1726 are also arranged at intervals in the row direction. The arrangement in Fig. 8(c) can also be described as, for example, a lattice arrangement, a houndstooth arrangement, or a checkerboard pattern.

[0195] As described above, by using a device using the organic light-emitting element according to the present invention, it is possible to achieve a display with good image quality and stability even over a long period of time.

[0196] [Included configuration] The disclosure of this embodiment includes the following configuration. (Configuration 1) An organic light-emitting device comprising, in this order, a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a second electrode, The charge generating section includes at least one n-type charge generating layer, the n-type charge generating layer includes at least a first organic compound and a second organic compound; The organic light-emitting device is characterized in that the first organic compound and the second organic compound satisfy the relationship represented by the following formulas [1] and [2-1]. |LUMO(H1)-LUMO(H2)|≦0.1ev [1] HOMO(H2)-HOMO(H1)>0.0eV [2-1] (In the above formulas [1] and [2-1], LUMO(H1) represents the LUMO energy level of the first organic compound, LUMO(H2) represents the LUMO energy level of the second organic compound, HOMO(H1) represents the HOMO energy level of the first organic compound, and HOMO(H2) represents the HOMO energy level of the second organic compound.)

[0197] (Configuration 2) The organic light-emitting device according to configuration 1, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [2-2]: HOMO(H2)-HOMO(H1)≧0.2eV [2-2] (Configuration 3) The organic light-emitting element according to structure 1 or 2, characterized in that the first organic compound is a nitrogen-containing aromatic compound, and the second organic compound is an aromatic hydrocarbon compound or an aromatic heterocyclic compound. (Configuration 4) 4. The organic light-emitting device according to any one of Structures 1 to 3, wherein the n-type charge generating layer further contains an alkali metal atom or an alkaline earth metal atom.

[0198] (Configuration 5) the first light-emitting unit has a first light-emitting layer; the first light-emitting layer includes at least a third organic compound and a first light-emitting compound; 5. The organic light-emitting device according to any one of configurations 1 to 4, wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [3]: LUMO(H3)-LUMO(D1)>HOMO(D1)-HOMO(H3) [3] (In the above formula [3], LUMO(H3) represents the LUMO energy level of the third organic compound, LUMO(D1) represents the LUMO energy level of the first light-emitting compound, HOMO(H3) represents the HOMO energy level of the third organic compound, and HOMO(D1) represents the HOMO energy level of the first light-emitting compound.)

[0199] (Configuration 6) The organic light-emitting device according to configuration 5, wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [4]: LUMO(H3)-LUMO(D1)≧0.1 eV [4] (Configuration 7) the first light-emitting layer further comprises a fourth organic compound; The organic light-emitting device according to the fifth or sixth configuration, wherein the third organic compound and the fourth organic compound satisfy the relationship represented by the following formula [5]: HOMO(H4)-HOMO(H3)≧0.1 eV [5] In the above formula [5], HOMO(H4) represents the HOMO energy level of the fourth organic compound.

[0200] (Configuration 8) An organic light-emitting device comprising, in this order, a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a second electrode, The charge generating section includes at least one n-type charge generating layer, the n-type charge generating layer includes at least a first organic compound and a second organic compound; the first organic compound is a nitrogen-containing aromatic compound; The organic light-emitting device is characterized in that the second organic compound is represented by the following general formula [I] or [II]: [ka] [In the above general formulas [I] and [II], X1 to X8 are carbon atoms having a substituent R, or nitrogen atoms. Y represents a carbon atom having substituents R1 and R2, or any one of an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. When Y in general formula [I] is a carbon atom having substituents R1 and R2, and in general formula [II], at least one of X1 to X8 represents a nitrogen atom. R, R1, and R2 are selected from a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted amino group, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkoxy group, and a cyano group. In X1 to X8, when the carbon atoms having the substituent R are adjacent to each other and the substituent R has a carbon atom, or when R1 and R2 have a carbon atom, the adjacent substituents may form a ring.]

[0201] (Configuration 9) 9. The organic light-emitting device according to configuration 8, wherein the second organic compound is represented by the following general formula [III]: [ka] [In the above general formula [III], R3 to R 10 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 10 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

[0202] (Configuration 10) 9. The organic light-emitting device according to configuration 8, wherein the second organic compound is represented by the following general formula [IV]: [ka] [In the above general formula [IV], R 11 ~R 16 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 11 ~R 16 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

[0203] (Configuration 11) 9. The organic light-emitting device according to configuration 8, wherein the second organic compound is represented by the following general formula [V]: [ka] [In the above general formula [V], X1 to X4 are carbon atoms or nitrogen atoms having a substituent R, and at least one of them represents a nitrogen atom. 17 ~R 20 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 17 ~R 20 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

[0204] (Configuration 12) 9. The organic light-emitting device according to claim 8, wherein the second organic compound is represented by the following general formula [VI]: [ka] [In the above general formula [VI], Y represents any one of an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. 21 ~R 28 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 21 ~R 28When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

[0205] (Configuration 13) an electron transport layer adjacent to the n-type charge generating layer on the first electrode side; 13. The organic light-emitting device according to any one of structures 8 to 12, wherein the electron transport layer contains an organic compound represented by the general formula [I] or [II]. (Configuration 14) 14. The organic light-emitting device according to any one of configurations 8 to 13, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [1]: |LUMO(H1)-LUMO(H2)|≦0.1ev [1] (In the above formula [1], LUMO(H1) represents the LUMO energy level of the first organic compound, and LUMO(H2) represents the LUMO energy level of the second organic compound.)

[0206] (Configuration 15) 15. The organic light-emitting device according to configuration 14, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [2-1]: HOMO(H2)-HOMO(H1)>0.0eV [2-1] (In the above formula [2-1], HOMO(H1) represents the HOMO energy level of the first organic compound, and HOMO(H2) represents the HOMO energy level of the second organic compound.)

[0207] (Configuration 16) 15. The organic light-emitting device according to configuration 14, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [2-2]: HOMO(H2)-HOMO(H1)≧0.2eV [2-2] (Configuration 17) 17. The organic light-emitting device according to any one of Structures 8 to 16, wherein the n-type charge generating layer further contains alkali metal atoms or alkaline earth metal atoms.

[0208] (Configuration 18) the first light-emitting unit has a first light-emitting layer; the first light-emitting layer includes at least a third organic compound and a first light-emitting compound; 18. The organic light-emitting device according to any one of configurations 8 to 17, wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [3]: LUMO(H3)-LUMO(D1)>HOMO(D1)-HOMO(H3) [3] (In the above formula [3], LUMO(H3) represents the LUMO energy level of the third organic compound, LUMO(D1) represents the LUMO energy level of the first light-emitting compound, HOMO(H3) represents the HOMO energy level of the third organic compound, and HOMO(D1) represents the HOMO energy level of the first light-emitting compound.)

[0209] (Configuration 19) 19. The organic light-emitting device according to configuration 18, wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [4]: LUMO(H3)-LUMO(D1)≧0.1 eV [4] (Configuration 20) the first light-emitting layer further comprises a fourth organic compound; 20. The organic light-emitting device according to claim 18 or 19, wherein the third organic compound and the fourth organic compound satisfy the relationship represented by the following formula [5]: HOMO(H4)-HOMO(H3)≧0.1 eV [5] In the above formula [5], HOMO(H4) represents the HOMO energy level of the fourth organic compound.

[0210] (Configuration 21) 21. A display device comprising: a display section having the organic light-emitting element according to any one of configurations 1 to 20; and a housing in which the display section is provided. (Configuration 22) An imaging element that receives light, and a display unit that displays an image captured by the imaging element, 21. A photoelectric conversion device, wherein the display section comprises the organic light-emitting element according to any one of configurations 1 to 20. (Configuration 23) 21. An electronic device comprising: a display unit having the organic light-emitting element according to any one of configurations 1 to 20; a housing in which the display unit is provided; and a communication unit provided in the housing for communicating with the outside. (Configuration 24) A wearable device comprising: a display unit having an organic light-emitting element according to any one of configurations 1 to 20; an optical system that collects light from the display unit; and a control device that controls the display of the display unit. (Configuration 25) 21. A lighting device comprising: a light source having the organic light-emitting element according to any one of configurations 1 to 20; and a housing in which the light source is provided. (Configuration 26) A moving body comprising: a lighting fixture having the organic light-emitting element according to any one of configurations 1 to 20; and a body on which the lighting fixture is provided. (Configuration 27) 21. An image forming apparatus comprising: a photoconductor; and an exposure light source for exposing the photoconductor, the exposure light source comprising the organic light-emitting element according to any one of configurations 1 to 20. EXAMPLES

[0211] Examples are shown below, but the present invention is not limited to the following contents. Example 1 In this example, a top-emission type stacked organic light-emitting device was fabricated by sequentially forming an anode as a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a cathode as a second electrode on a substrate. A blue light-emitting layer was used for the first light-emitting unit, and a yellow light-emitting layer was used for the second light-emitting unit, forming these layers in that order, to fabricate an organic light-emitting device with a double-sided emission structure.

[0212] First, an ITO film was formed on a glass substrate, and an ITO electrode (anode) was formed by performing a desired patterning process. At this time, the film thickness of the ITO electrode was set to 100 nm. The substrate on which the ITO electrode was formed in this manner was used as an ITO substrate. Next, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a cathode, as shown in Table 3 below, were formed in that order on the ITO substrate by vacuum deposition using resistance heating in a vacuum chamber. At this time, the electrode areas of the opposing electrodes (anode and cathode) were set to 3 mm2. 2 After the layers up to the cathode were formed, the substrate was transferred to a glove box and sealed with a glass cap containing a desiccant in a nitrogen atmosphere to obtain a stacked organic light-emitting element.

[0213] [Table 3]

[0214] (Examples 2 to 17, Comparative Examples 1 and 2) An organic light-emitting device was produced in the same manner as in Example 1, except that the second organic compound and the alkali metal were changed to the compounds shown in Table 4. The voltage-current characteristics of the obtained organic light-emitting device were measured using a microammeter 4140B manufactured by Hewlett-Packard, and the emission spectrum was measured using an SR-3 manufactured by Topcon. The organic light-emitting devices of Examples 1 to 17 exhibited good white light emission. 2 A drive test of the organic light-emitting element was performed under a constant current condition of 100 V, and the LT80, which is the time it takes for the luminance to deteriorate by 20% from the initial luminance, and the drive voltage were evaluated. The results are shown in Table 4. The voltage ratio and durability ratio values ​​are relative values ​​when the LT80 and voltage of Comparative Example 1 are set to 1.0. The ΔLUMO and ΔHOMO in Table 4 are as follows: ΔLUMO=|LUMO(H1)-LUMO(H2)| ΔHOMO = HOMO(H2) - HOMO(H1)

[0215] [Table 4]

[0216] (Examples 18 to 23, Comparative Example 3) An organic light-emitting device was produced in the same manner as in Example 1, except that the first electron transport layer was changed from ET1 to the second organic compound shown in Table 5, and the LT80 and driving voltage were evaluated. The results are shown in Table 5. The voltage ratio and durability ratio values ​​are relative values ​​when the LT80 and voltage of Comparative Example 3 were set to 1.0. ΔLUMO and ΔHOMO are the same as in Table 4.

[0217] [Table 5]

[0218] From Tables 4 and 5, it can be seen that, as in Examples 1 to 23, by mixing the second organic compound satisfying both formula [1] and formula [2-1] in the n-type charge generation layer, the second organic compound traps only holes without trapping electrons, thereby suppressing the deterioration of the first organic compound due to holes. As a result, the deterioration of the entire n-type charge generation layer can be suppressed, and since the n-type charge generation layer has a hole trap configuration, it becomes difficult for holes to reach the p-type charge generation layer, so that the deterioration of the organic light-emitting element can be suppressed. In addition, since electrons are not trapped, durability can be improved and a lower voltage can be achieved at the same time.

[0219] In the organic light-emitting devices of Examples 1 to 11, the second organic compound is an aromatic hydrocarbon compound and satisfies both formula [1] and formula [2-2], and therefore the devices are particularly excellent in durability. Examples 12 to 23 are examples using organic compounds represented by general formula [I] or [II], and in particular, Examples 19, 21, and 23 use in the first electron transport layer a compound similar to the second organic compound used in the n-type charge generating layer, so that the lithium atoms used as the alkali metal atoms are prevented from diffusing into the light emitting layer. As a result, it was found that the quenching of the light emitting material by the lithium atoms is prevented, and the durability of the organic light emitting device is improved.

[0220] On the other hand, in Comparative Example 1, the second organic compound does not satisfy formula [1], so the electron mobility is low, and the compound structure has a phenanthroline skeleton, so the effect of suppressing alkali metal diffusion is low, and the stability against holes is also low. Therefore, the organic light-emitting devices of Comparative Examples 1 and 3 have high voltage and poor durability. In Comparative Example 2, ET3 is used as the second organic compound, but since ET3 has two phenanthroline skeletons, the diffusibility of alkali metals is further improved, and the durability is reduced.

[0221] (Examples 24 to 26) An organic light-emitting device was produced in the same manner as in Example 1, except that the second organic compound in Example 1 was changed to the compound shown in Table 6, and the LT80 and driving voltage were evaluated. The results are shown in Table 5. ΔLUMO and ΔHOMO are the same as in Table 4.

[0222] [Table 6]

[0223] In Examples 24 to 26, although the requirements of formula [1] are not satisfied, the second organic compound of the n-type charge generating layer is an organic compound of general formula [I] or [II], and does not have a phenanthroline skeleton, which is possessed by the second organic compound used in Comparative Examples 1 and 2. This results in a high effect of suppressing the diffusion of alkali metals and high stability against holes. Therefore, even though Examples 24 to 26 do not satisfy formula [1] and formula [2-1], they are more durable than the organic light-emitting devices of Comparative Examples 1 and 2.

[0224] Example 27 The same organic light-emitting device as in Example 4 was produced by changing the light-emitting compound in the first light-emitting layer from BD8 to BD1, and the LT80 and driving voltage were evaluated. The results are shown in Table 7. In Table 7, ΔLUMO and ΔHOMO are as follows. ΔLUMO=LUMO(H3)-LUMO(D1) ΔHOMO = HOMO(D1) - HOMO(H3)

[0225] [Table 7]

[0226] As shown in Table 7, Example 4 has a large ΔLUMO (LUMO (H3) - LUMO (D1)) in formula [4], and is an emitting layer in which electrons are trapped, and holes are not trapped. On the other hand, Example 27 is a system in which electrons are not trapped, and holes are trapped. When there are an excess of holes in the emitting layer, the excitons generated in the emitting layer are accelerated to degrade via a cationic state. For this reason, Example 27 is affected by the degraded mode in the emitting layer, and the effect of the n-type charge generating layer according to the present invention is reduced. Therefore, in the present invention, a configuration in which holes are not trapped in the emitting layer of the first emitting unit, that is, an electron trap type configuration as shown in Example 4, is more preferable, and the effect of the n-type charge generating layer can be more significantly exhibited.

[0227] (Example 28) An organic light-emitting device was fabricated in the same manner as in Example 4, except that EM3 was added to the first light-emitting layer as a fourth organic compound at 30% by mass, and a ternary light-emitting layer was formed by setting the mass ratio of EM1:EM3:BD8 to 68.5:30:1.5, and the LT80 and driving voltage were evaluated. The results are shown in Table 8. The ΔHOMO in Table 8 is as follows: ΔHOMO = HOMO(H4) - HOMO(H3)

[0228] [Table 8]

[0229] Example 24 is a system in which an assist material that traps holes is introduced into the light-emitting layer, in contrast to Example 4, which is an electron trap system. This makes it possible to form a light-emitting layer that traps both electrons and holes. Therefore, compared to Example 4, which had good characteristics, the leakage of holes to the n-type charge generation layer can be further suppressed, improving durability. [Explanation of symbols]

[0230] 200: first electrode, 300: first light-emitting unit, 304: first light-emitting layer, 306: first electron transport layer, 400: charge generating section, 500: second light-emitting unit, 600: second electrode, 1000, 1300, 1310: display device, 1100: imaging device, 1104, 1203, 1313: housing, 1200: electronic device, 1201: display section, 1302, 1311, 1312: display section, 1707: photoconductor, 1708: exposure light source

Claims

1. An organic light-emitting device comprising, in this order, a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a second electrode, The charge generating portion includes at least one n-type charge generating layer, the n-type charge generating layer includes at least a first organic compound and a second organic compound; The organic light-emitting device is characterized in that the first organic compound and the second organic compound satisfy the relationship represented by the following formulas [1] and [2-1]. |LUMO(H1)-LUMO(H2)|≦0.1ev [1] HOMO(H2)-HOMO(H1)>0.0eV [2-1] (In the above formulas [1] and [2-1], LUMO (H1) represents the LUMO energy level of the first organic compound, LUMO (H2) represents the LUMO energy level of the second organic compound, HOMO (H1) represents the HOMO energy level of the first organic compound, and HOMO (H2) represents the HOMO energy level of the second organic compound.)

2. 2. The organic light-emitting device according to claim 1, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [2-2]: HOMO(H2)-HOMO(H1)≧0.2eV [2-2]

3. 2. The organic light-emitting device according to claim 1, wherein the first organic compound is a nitrogen-containing aromatic compound, and the second organic compound is an aromatic hydrocarbon compound or an aromatic heterocyclic compound.

4. The organic light emitting device according to claim 1 , wherein the n-type charge generating layer further comprises an alkali metal atom or an alkaline earth metal atom.

5. the first light-emitting unit has a first light-emitting layer; the first light-emitting layer includes at least a third organic compound and a first light-emitting compound; The organic light-emitting element according to claim 1 , wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [3]: LUMO (H3) - LUMO (D1) > HOMO (D1) - HOMO (H3) [3] [In the above formula [3], LUMO(H3) represents the LUMO energy level of the third organic compound, LUMO(D1) represents the LUMO energy level of the first light-emitting compound, HOMO(H3) represents the HOMO energy level of the third organic compound, and HOMO(D1) represents the HOMO energy level of the first light-emitting compound.]

6. The organic light-emitting device according to claim 5 , wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [4]: LUMO(H3)-LUMO(D1)≧0.1eV [4]

7. the first light-emitting layer further comprises a fourth organic compound; The organic light-emitting device according to claim 5 , wherein the third organic compound and the fourth organic compound satisfy a relationship represented by the following formula [5]: HOMO(H4)-HOMO(H3)≧0.1eV [5] (In the above formula [5], HOMO(H4) represents the HOMO energy level of the fourth organic compound.)

8. An organic light-emitting device comprising, in this order, a first electrode, a first light-emitting unit, a charge generating section, a second light-emitting unit, and a second electrode, The charge generating portion includes at least one n-type charge generating layer, the n-type charge generating layer includes at least a first organic compound and a second organic compound; the first organic compound is a nitrogen-containing aromatic compound, The organic light-emitting device is characterized in that the second organic compound is represented by the following general formula [I] or [II]: 【Chemistry 1】 [In the above general formulas [I] and [II], X 1 ~X 8 is a carbon atom having a substituent R, or a nitrogen atom. Y is a substituent R 1 , R 2 or any one of an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. 1 , R 2 In the case of a carbon atom having the general formula [II], X 1 ~X 8 At least one of R and R represents a nitrogen atom. 1 , R 2 is selected from a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted amino group, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkoxy group, and a cyano group. 1 ~X 8 In the formula (I), when the carbon atoms having the substituent R are adjacent to each other and the substituent R has a carbon atom, and R 1 , R 2 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

9. The organic light-emitting device according to claim 8 , wherein the second organic compound is represented by the following general formula [III]: 【Chemistry 2】 [In the above general formula [III], R 3 ~R 10 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 3 ~R 10 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

10. The organic light-emitting device according to claim 8 , wherein the second organic compound is represented by the following general formula [IV]: 【Chemistry 3】 [In the above general formula [IV], X 1 ~X 4 is a carbon atom having a substituent R or a nitrogen atom, and at least one of R and R is a nitrogen atom. 11 ~R 16 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 11 ~R 16 When has a carbon atom, adjacent substituents may form a ring.

11. The organic light-emitting device according to claim 8 , wherein the first organic compound is represented by the following general formula [V]: 【Chemistry 4】 [In the above general formula [V], X 1 ~X 4 is a carbon atom having a substituent R or a nitrogen atom, and at least one of R and R is a nitrogen atom. 17 ~R 20 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 17 ~R 20 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

12. The organic light-emitting device according to claim 8 , wherein the second organic compound is represented by the following general formula [VI]: 【Chemistry 5】 [In the above general formula [VI], Y represents any one of an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. 21 ~R 28 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heterocyclic group. 21 ~R 28 When has a carbon atom, adjacent substituents may be bonded to each other to form a ring.

13. an electron transport layer adjacent to the n-type charge generating layer on the first electrode side; The organic light-emitting element according to claim 8 , wherein the electron transport layer contains an organic compound represented by the general formula [I] or [II].

14. The organic light-emitting device according to claim 8 , wherein the first organic compound and the second organic compound satisfy a relationship represented by the following formula [1]: |LUMO(H1)-LUMO(H2)|≦0.1ev [1] (In the above formula [1], LUMO (H1) represents the LUMO energy level of the first organic compound, and LUMO (H2) represents the LUMO energy level of the second organic compound.)

15. The organic light-emitting device according to claim 14, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [2-1]: HOMO(H2)-HOMO(H1)>0.0eV [2-1] (In the above formula [2-1], HOMO (H1) represents the HOMO energy level of the first organic compound, and HOMO (H2) represents the HOMO energy level of the second organic compound.)

16. The organic light-emitting device according to claim 14, wherein the first organic compound and the second organic compound satisfy the relationship represented by the following formula [2-2]: HOMO(H2)-HOMO(H1)≧0.2eV [2-2]

17. The organic light emitting device according to claim 8 , wherein the n-type charge generating layer further comprises an alkali metal atom or an alkaline earth metal atom.

18. the first light-emitting unit has a first light-emitting layer; the first light-emitting layer includes at least a third organic compound and a first light-emitting compound; The organic light-emitting element according to claim 8 , wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [3]: LUMO (H3) - LUMO (D1) > HOMO (D1) - HOMO (H3) [3] [In the above formula [3], LUMO(H3) represents the LUMO energy level of the third organic compound, LUMO(D1) represents the LUMO energy level of the first light-emitting compound, HOMO(H3) represents the HOMO energy level of the third organic compound, and HOMO(D1) represents the HOMO energy level of the first light-emitting compound.]

19. The organic light-emitting element according to claim 18 , wherein the third organic compound and the first light-emitting compound satisfy the relationship represented by the following formula [4]: LUMO(H3)-LUMO(D1)≧0.1eV [4]

20. the first light-emitting layer further comprises a fourth organic compound; The organic light-emitting device according to claim 18 , wherein the third organic compound and the fourth organic compound satisfy a relationship represented by the following formula [5]: HOMO(H4)-HOMO(H3)≧0.1eV [5] (In the above formula [5], HOMO(H4) represents the HOMO energy level of the fourth organic compound.)

21. A display device comprising: a display section having the organic light-emitting element according to claim 1 ; and a housing in which the display section is provided.

22. An imaging element that receives light, and a display unit that displays an image captured by the imaging element, The photoelectric conversion device, wherein the display section comprises the organic light-emitting element according to claim 1 .

23. 21. An electronic device comprising: a display unit having the organic light-emitting element according to claim 1; a housing in which the display unit is provided; and a communication unit provided in the housing and configured to communicate with an external device.

24. 21. A wearable device comprising: a display unit having the organic light-emitting element according to claim 1; an optical system for concentrating light from the display unit; and a control device for controlling display of the display unit.

25. 21. A lighting device comprising: a light source having the organic light-emitting element according to claim 1; and a housing in which the light source is provided.

26. 21. A moving body comprising: a lighting device having the organic light-emitting element according to claim 1; and a body on which the lighting device is provided.

27. 21. An image forming apparatus comprising: a photoconductor; and an exposure light source for exposing said photoconductor, said exposure light source comprising the organic light emitting element according to claim 1.

Images