WO2018154408A1

WO2018154408A1 - Light-emitting element, light-emitting device, electronic device, and illumination device

Info

Publication number: WO2018154408A1
Application number: PCT/IB2018/050863
Authority: WO
Inventors: 小松のぞみ; 川上祥子; 上坂文香
Original assignee: 株式会社半導体エネルギー研究所
Priority date: 2017-02-21
Filing date: 2018-02-13
Publication date: 2018-08-30

Abstract

Provided is a highly reliable light-emitting element having excellent light emission efficiency. The light-emitting element comprises, in the light-emitting layer thereof, an organic compound having a heteroaromatic ring including at least two nitrogens. When MS/MS analysis is performed on the light-emitting layer in positive mode, an MS spectrum of fragment ions having C=N bonds and derived from the heteroaromatic ring including at least two nitrogens in the organic compound is detected. Since the organic compound for which the fragment ions are observed is thermally and electrochemically stable, a highly reliable light-emitting element having excellent light emission efficiency can be provided.

Description

LIGHT EMITTING ELEMENT, LIGHT EMITTING DEVICE, ELECTRONIC DEVICE, AND LIGHTING DEVICE

One embodiment of the present invention relates to a novel light-emitting element. Alternatively, the present invention relates to a light-emitting element in which fragment ions having a specific substituent are detected when MS / MS analysis is performed. Alternatively, the present invention relates to a light-emitting device, an electronic device, and a lighting device each having the light-emitting element.

Note that one embodiment of the present invention is not limited to the above technical field. One embodiment of the present invention relates to an object, a method, or a manufacturing method. Or this invention relates to a process, a machine, a manufacture, or a composition (composition of matter). In particular, one embodiment of the present invention relates to a semiconductor device, a light-emitting device, a display device, a lighting device, a light-emitting element, and manufacturing methods thereof.

A light-emitting element (organic EL element) using electroluminescence (EL) using an organic compound has been put into practical use. The basic structure of these light-emitting elements is such that an organic compound layer (EL layer) containing a light-emitting material is sandwiched between a pair of electrodes. Light emission from the light-emitting material can be obtained by applying a voltage to this element, injecting carriers, and utilizing the recombination energy of the carriers.

Since such a light-emitting element is a self-luminous type, when used as a display pixel, there are advantages such as high visibility and no need for a backlight, and it is suitable as a flat panel display element. In addition, a display using such a light emitting element has a great advantage that it can be manufactured to be thin and light. Another feature is that the response speed is very fast.

Further, since these light emitting elements can continuously form a light emitting layer in two dimensions, light emission can be obtained in a planar shape. This is a feature that is difficult to obtain with a point light source typified by an incandescent bulb or LED, or a line light source typified by a fluorescent lamp. In addition, since light emitted from an organic compound can be emitted without containing ultraviolet light by selecting a material, the utility value as a surface light source applicable to illumination or the like is also high.

Since displays and illumination devices using organic EL elements are suitable for various electronic devices in this way, research and development are being pursued for light-emitting elements with better efficiency and element lifetime. In particular, an organic compound is mainly used for the EL layer, which has a great influence on the improvement of the element characteristics of the light-emitting element. Therefore, selection of the organic compound used for the EL layer is important.

As an organic compound that can be used for a light-emitting element, a high T1 level and carrier (electron or hole) transportability are mainly required, and thus an organic compound having a nitrogen-containing heteroaromatic ring is used. In particular, an organic compound having a nitrogen-containing heteroaromatic ring having two or more nitrogen atoms (for example, Patent Document 1) is useful, but the type of the nitrogen-containing heteroaromatic ring, the nitrogen-containing heteroaromatic ring and the substituent Depending on the coupling position, the characteristics of the light emitting element are adversely affected. Therefore, it is important to use a material having a large binding energy for each bond in the organic compound for the light-emitting element.

JP 2011-201869 A

A light emitting element using an organic compound such as an organic EL element is manufactured by a vacuum deposition method or a wet method using an organic solvent. Therefore, organic compounds are required to be stable from external stimuli such as heating during vacuum deposition and dissolution in a solvent. Since a light-emitting element using the organic compound has good reliability, development of a light-emitting element using an organic compound in which individual chemical bonds are stable is required.

Therefore, an object of one embodiment of the present invention is to provide a novel light-emitting element using an organic compound having a stable bond. In particular, an object of the present invention is to provide a light-emitting element in which fragment ions having a specific substituent are detected when MS / MS analysis is performed. Another object of one embodiment of the present invention is to provide a light-emitting element with high emission efficiency. Another object of one embodiment of the present invention is to provide a light-emitting element with high reliability.

Note that the description of the above problems does not disturb the existence of other problems. Note that one embodiment of the present invention does not necessarily have to solve all of these problems. Problems other than the above are obvious from the description of the specification and the like, and problems other than the above can be extracted from the description of the specification and the like.

In one embodiment of the present invention, an EL layer is provided between a pair of electrodes, and by performing MS / MS analysis on the EL layer, light emission in which fragment ions in which a structure represented by the following general formula (g0) is ionized is detected It is an element.

In the general formula (g0), Ar ^{1 to} Ar ⁴ each independently represent a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 25 carbon atoms, and n ^{1 to} n ⁴ each independently represents 0 or 1 B ¹ represents any ^one of hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, * On carbon (C) and nitrogen (N) represents an unpaired electron.

In the above configuration, it is preferable that fragment ions in which the structure represented by the following general formula (g1) is ionized are also detected. In addition, when the molecular structures represented by the general formula (g0) and the general formula (g1) are the same, the same fragment ion is observed, so that one type of fragment ion is detected.

In General Formula (G2), Ar ^{5 to} Ar ⁸ each independently represent a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 25 carbon atoms, and m ^{1 to} m ⁴ each independently represents 0 or 1 B ² represents any one of hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, * On carbon (C) and nitrogen (N) represents an unpaired electron.

In the above structure, it is preferable that at least one of Ar ^{1 to} Ar ⁴ in the general formula (g0) is a substituted or unsubstituted phenylene group because a light-emitting element having favorable carrier transportability can be obtained.

In the above structure, when the fragment ion in which the structure represented by the general formula (g0) is ionized belongs to any one of the following structural formulas (100) to (103), the material has a favorable carrier transport property. A light emitting element is preferable because the driving voltage can be reduced.

In Structural Formulas (100) to (103), “上の” on carbon (C) and nitrogen (N) represents an unpaired electron.

In the above structure, the EL layer preferably further includes an organic compound represented by the following general formula (G0), and the fragment ions are preferably derived from the organic compound.

In General Formula (G0), A represents a heteroaromatic hydrocarbon group having 1 to 20 carbon atoms containing two or more substituted or unsubstituted nitrogen atoms, and Ar ^{1 to} Ar ¹² are each independently substituted or unsubstituted. A divalent aromatic hydrocarbon group having 6 to 25 carbon atoms; n ^{1 to} n ⁴ , m ^{1 to} m ⁴ , and l ^{1 to} l ⁴ each independently represents 0 or 1; and B ^{1 to} B ³ Each independently represents hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms.

The portion of the bond in the organic compound represented by the general formula (G0) having the lowest bond energy is a nitrogen-carbon bond or a nitrogen-nitrogen bond in a heteroaromatic ring containing two or more nitrogens represented by A. It is. The fragment ion in which the structure represented by the general formula (g0) or (g1) detected by cleavage of the general formula (G0) is ionized has a C═N bond derived from the nitrogen-carbon bond. Yes. The observation of the C═N group means that the organic compound represented by the general formula (G0) has a stable structure with little distortion and the like.

In the above structure, the EL layer preferably further includes an organic compound represented by the following general formula (G1), and the fragment is preferably derived from the organic compound. Furthermore, the fragment ion in which the structure represented by the general formula (g0) is ionized is preferably an ionized structure represented by the general formula (100).

In General Formula (G1), A represents a heteroaromatic hydrocarbon group having 1 to 20 carbon atoms containing two or more substituted or unsubstituted nitrogen atoms, and Ar ^{5 to} Ar ¹² are each independently substituted or unsubstituted. A divalent aromatic hydrocarbon group having 6 to 25 carbon atoms, m ^{1 to} m ⁴ and l ^{1 to} l ⁴ each independently represents 0 or 1, B ² and B ³ each independently represent hydrogen, This represents any one of a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, and in the structural formula (100), carbon ( C on nitrogen and nitrogen (N) represents an unpaired electron.

In the above structure, when the heteroaromatic ring compound includes any of a triazine skeleton, a pyrimidine skeleton, an imidazole skeleton, or a triazole skeleton, the organic compound has a high T1 level and is electrochemically stable, and thus emits light. This is preferable because a light-emitting element having high efficiency and high reliability can be obtained.

In the above structure, the EL layer preferably includes any one of organic compounds represented by the following general formula (G2) or (G3), and the fragment ions are preferably derived from the organic compound.

In General Formulas (G2) and (G3), Ar ^{1 to} Ar ¹² each independently represent a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 25 carbon atoms, n ^{1 to} n ⁴ , m ¹ To m ⁴ and l ^{1 to} l ⁴ each independently represents 0 or 1, and B ^{1 to} B ³ each independently represent hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or It represents any one of a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, and Q represents carbon or nitrogen. In addition, when Q is carbon, Q may have a substituent. When Q is carbon and has no substituent, Q represents CH.

In the above structure, the EL layer further includes an organic compound represented by the following general formula (G4) or (G5), and the fragment is preferably derived from the organic compound. Furthermore, the molecular structure represented by the general formula (g0) is preferably represented by the general formula (100).

In the above configuration, when the EL layer is dissolved in a solvent and MS / MS analysis is performed, the MS spectrum intensity of at least one fragment ion is detected with an intensity of 100 times or more compared to the precursor ion spectrum intensity. preferable.

In the above structure, the organic compound preferably has a molecular weight of 300 or more and 1000 or less. By setting it as such a structure, it can be set as the organic compound excellent in sublimation property.

In the above structure, it is preferable that at least one of B ² and B ³ in the general formulas (G0) to (G5) has a substituted or unsubstituted benzofuran skeleton or benzothiophene skeleton. With the above structure, the organic compound can have improved heat resistance while having a high T1 level.

In the above configuration, the fragment ion is a cation, and the MS / MS analysis is preferably performed in the positive mode. With the above configuration, detection can be performed with high sensitivity.

Another embodiment of the present invention is an electronic device including the light-emitting element having the above structure and at least one of a housing and a touch sensor. Another embodiment of the present invention is a lighting device including the light-emitting element having any of the above structures and at least one of a housing, a connection terminal, and a protective cover. One embodiment of the present invention includes not only a light-emitting device including a light-emitting element but also an electronic device including the light-emitting device. Therefore, a light-emitting device in this specification refers to an image display device or a light source (including a lighting device). In addition, a display module in which a connector such as an FPC (Flexible Printed Circuit) or TCP (Tape Carrier Package) is attached to the light emitting element, a display module in which a printed wiring board is provided at the end of the TCP, or a COG (Chip On) in the light emitting element. A display module in which an IC (integrated circuit) is directly mounted by a glass method is also an embodiment of the present invention.

According to one embodiment of the present invention, a novel light-emitting element using an organic compound having a stable bond can be provided. In particular, when MS / MS analysis is performed, a light-emitting element in which fragment ions having a specific substituent can be detected can be provided. In one embodiment of the present invention, a light-emitting element with high emission efficiency can be provided. Alternatively, according to one embodiment of the present invention, a light-emitting element with high reliability can be provided.

Note that the description of these effects does not disturb the existence of other effects. Note that one embodiment of the present invention does not necessarily have all of these effects. Note that the effects other than these are obvious from the description of the specification, drawings, claims, and the like, and it is possible to extract other effects from the descriptions of the specification, drawings, claims, and the like.

FIG. 9 is a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention. 4A and 4B illustrate a method for manufacturing an MS / MS analysis sample regarding the light-emitting element of one embodiment of the present invention. FIGS. 3A and 3B are a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a diagram illustrating a correlation between energy levels of a light-emitting layer. FIGS. FIGS. 3A and 3B are a schematic cross-sectional view of a light-emitting element of one embodiment of the present invention and a diagram illustrating a correlation between energy levels of a light-emitting layer. FIGS. 1 is a conceptual diagram of an active matrix light-emitting device according to one embodiment of the present invention. 1 is a conceptual diagram of an active matrix light-emitting device according to one embodiment of the present invention. 1 is a conceptual diagram of an active matrix light-emitting device according to one embodiment of the present invention. 1 is a schematic diagram of an electronic device according to one embodiment of the present invention. 1 is a schematic diagram of an electronic device according to one embodiment of the present invention. FIG. 10 illustrates a lighting device according to one embodiment of the present invention. FIG. 10 illustrates a lighting device according to one embodiment of the present invention. The figure explaining the MS spectrum of the compound based on an Example. 6A and 6B illustrate current efficiency-luminance characteristics of a light-emitting element according to an example. 6A and 6B illustrate voltage-current density characteristics of a light-emitting element according to an example. 6A and 6B illustrate an external quantum efficiency-luminance characteristic of a light-emitting element according to an example. The figure explaining the emission spectrum based on an Example. The figure explaining the reliability test result based on an Example. The figure explaining the MS spectrum of the compound based on an Example. The figure explaining the MS spectrum of the compound based on an Example. The figure explaining the MS spectrum of the compound based on an Example. The figure explaining the MS spectrum of the compound based on an Example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and various changes can be made in form and details without departing from the spirit and scope of the present invention. Therefore, the present invention is not construed as being limited to the description of the embodiments below.

Note that the position, size, range, and the like of each component shown in the drawings and the like may not represent the actual position, size, range, etc. for easy understanding. Therefore, the disclosed invention is not necessarily limited to the position, size, range, or the like disclosed in the drawings and the like.

In this specification and the like, the ordinal numbers attached as the first and second are used for convenience, and may not indicate the process order or the stacking order. Therefore, for example, the description can be made by appropriately replacing “first” with “second” or “third”. In addition, the ordinal numbers described in this specification and the like may not match the ordinal numbers used to specify one embodiment of the present invention.

In this specification and the like, in describing the structure of the invention with reference to drawings, the same reference numerals may be used in common in different drawings.

In addition, in this specification and the like, the terms “film” and “layer” can be interchanged. For example, the term “conductive layer” may be changed to the term “conductive film”. Alternatively, for example, the term “insulating film” may be changed to the term “insulating layer” in some cases.

In this specification and the like, room temperature refers to a temperature in the range of 0 ° C. to 40 ° C.

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

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

The light-emitting element 150 includes a pair of electrodes (the electrode 101 and the electrode 102) and the EL layer 100 provided between the pair of electrodes. The EL layer 100 includes at least a light emitting layer 130.

In addition to the light-emitting layer 130, the EL layer 100 illustrated in FIG. 1A includes functional layers such as a hole injection layer 111, a hole transport layer 112, an electron transport layer 118, and an electron injection layer 119.

Note that in this embodiment, the electrode 101 is an anode and the electrode 102 is a cathode of the pair of electrodes, but the structure of the light-emitting element 150 is not limited thereto. That is, the electrode 101 may be a cathode, the electrode 102 may be an anode, and the layers stacked between the electrodes may be reversed. That is, from the anode side, the hole injection layer 111, the hole transport layer 112, the light emitting layer 130, the electron transport layer 118, and the electron injection layer 119 may be stacked.

Note that the structure of the EL layer 100 is not limited to the structure illustrated in FIG. 1A and includes at least the light-emitting layer 130, the hole-injection layer 111, the hole-transport layer 112, the electron-transport layer 118, and the electron-injection Each of the layers 119 may or may not be included. In addition, the EL layer 100 can reduce the hole or electron injection barrier, improve the hole or electron transport property, inhibit the hole or electron transport property, or suppress the quenching phenomenon caused by the electrode. It is good also as a structure which has a functional layer which has a function of being able to suppress child diffusion. Note that each functional layer may be a single layer or a structure in which a plurality of layers are stacked.

FIG. 1B is a schematic cross-sectional view illustrating an example of the light-emitting layer 130 illustrated in FIG. A light-emitting layer 130 illustrated in FIG. 1B includes at least a host material 131 and a guest material 132.

Although an organic compound having a nitrogen-containing heteroaromatic hydrocarbon group is used as the host material 131, sufficient device characteristics may not be obtained depending on the type of the substituent and the bonding position.

Here, the present inventors emit an organic compound represented by the following general formula (G0), in which the fragment ion represented by the general formula (g0) is detected when the MS / MS analysis is performed in the positive mode. It was found that a light-emitting element having good light emission efficiency, low driving voltage, and good reliability can be obtained by using it in the EL layer of the element. The fragment ion is preferably a cation because of its high detection intensity. The cation may be a radical cation or a cation adduct such as a proton adduct, a sodium ion adduct, or an ammonia ion adduct. good.

Thus, according to one embodiment of the present invention, a light-emitting element which has an EL layer between a pair of electrodes and detects fragment ions in which the structure represented by the general formula (g0) is ionized when MS / MS analysis is performed on the EL layer It is.

The organic compound represented by the general formula (G0) is an organic compound having a heteroaromatic ring having at least two nitrogen atoms. Since such an organic compound has a high T1 level, when a material capable of converting triplet excitons such as a phosphorescent material into light emission is used for the guest material 132, the host material 131 can be preferably used. In addition, since the organic compound is excellent in electron transporting property, a low driving voltage can be realized by using it in a light-emitting element.

When the fragment ion in which the structure represented by the general formula (g0) is ionized is derived from the organic compound represented by the general formula (G0), information on the fragment ion in which the structure represented by the general formula (g0) is ionized is represented by the general formula ( The information of the organic compound represented by G0) is included. Therefore, the stability of the bond in the organic compound represented by the general formula (G0) can be evaluated from the fragment ion in which the structure represented by the general formula (g0) is ionized.

In the general formula (G0), as A, for example, a substituted or unsubstituted triazinyl group, pyrimidinyl group, pyrazyl group, triazolyl group, imidazolyl group, quinazolinyl group, quinoxanyl group, dibenzoquinazolinyl group, dibenzoquinoxalinyl And trivalent groups such as a benzofuropyrimidinyl group, a benzothienopyrimidinyl group, a benzofuropyrazinyl group, a benzothienopyrazinyl group, and an indolocarbazolyl group. A is not limited to the above.

A preferably has a conjugated double bond in the order of nitrogen-carbon-nitrogen (N—C—N), and the carbon atom in the conjugated double bond preferably has an aryl group or an arylene group. In particular, A is preferably a trivalent group of a triazinyl group, a pyrimidinyl group, an imidazolyl group, or a triazolyl group. Such a substituent has a particularly high T1 level, a high electron transporting property, and is electrochemically stable. Therefore, by using an organic compound having such a substituent for a light-emitting element, high luminous efficiency can be obtained. Accordingly, a light-emitting element having a low driving voltage and good reliability can be provided.

In general, a carbon-carbon conjugated double bond has a larger binding energy than a nitrogen-carbon conjugated double bond. Therefore, in A in the general formula (G0), a divalent or monovalent aromatic hydrocarbon group or a heteroaromatic hydrocarbon group (Ar ¹ , Ar ⁵ , Ar ⁹ or n _{1 to} n ₄ , m bonded to A _{When 1 to} m ₄ and l _{1 to} l ₄ are 0, B _{1 to} B ₃ are preferably bonded to a carbon atom in a nitrogen-carbon-nitrogen (N—C—N) conjugated double bond in A. . In other words, when A in General Formula (G0) has a substituent, the substituent and A preferably have a bond on a carbon atom. In this case, since the bond energy between A and the substituent is larger than in the case of having a bond on a nitrogen atom, the organic compound represented by the general formula (G0) has a thermally and chemically stable structure. It becomes. Therefore, when the organic compound is used for a light-emitting element, a light-emitting element with favorable reliability can be provided.

In the above general formula (G0), B may have a heteroaromatic ring or an aromatic hydrocarbon group. When B has a heteroaromatic ring, the organic compound represented by General Formula (G0) is preferable because it has a structure with excellent carrier transportability. It is preferable that B is an aromatic hydrocarbon group because the structure is easy to synthesize and has excellent heat resistance.

In addition, since the organic compound represented by the general formula (G0) has excellent carrier (electron or hole) transportability, the organic compound can be preferably used as the hole transport layer 112 and the electron transport layer 118.

With respect to the EL layer of the light-emitting element having the organic compound represented by the general formula (G0), it is preferable to detect fragment ions in which the structure represented by the general formula (g0) is ionized when MS / MS analysis is performed. The fragment ion belongs to a substance obtained by cleaving the organic compound at a carbon-nitrogen conjugated double bond portion of a heteroaromatic hydrocarbon group containing two or more nitrogen atoms (A in the general formula (G0)).

The MS / MS analysis is preferably performed in the positive mode. Since substituents containing nitrogen generally have a high proton affinity, the detection in the positive mode can be performed with higher sensitivity than in the negative mode. In addition, when an organic compound having a conjugated structure is ionized, an anion has a shorter ion lifetime and is more unstable than a cation, and therefore, measurement in the positive mode enables highly sensitive detection. Note that MS / MS analysis can also be performed in a negative mode.

When MS / MS analysis is performed, the detected fragment ions are ions generated by cleavage of a bond having a low binding energy in the material subjected to MS / MS analysis. In general, a carbon-nitrogen conjugated double bond or a nitrogen-nitrogen bond has a lower binding energy than a C═C bond or a carbon-carbon conjugated double bond. Therefore, an organic compound represented by the general formula (G0), which is used in a light-emitting element, has a structure in which a conjugated system extends over the entire molecule and has a heteroaromatic hydrocarbon group containing two or more nitrogen atoms. When performing MS / MS analysis, it can be said that a partial structure having a carbon-nitrogen conjugated double bond or a nitrogen-nitrogen conjugated double bond is easily cleaved. However, when the molecule has a carbon-nitrogen conjugated double bond or a partial structure whose bond energy is lower than that of the nitrogen-nitrogen bond, for example, when the molecule has a distorted partial structure, it is represented by the general formula (g0). Instead of fragment ions whose structure is ionized, fragment ions in which a partial structure having a binding energy lower than that of the carbon-nitrogen conjugated double bond is cleaved are detected.

Therefore, when MS / MS analysis is performed on the organic compound represented by the general formula (G0), when a fragment ion in which the structure represented by the general formula (g0) is ionized is detected, the general formula (G0) has a molecular structure. It can be said that the structure is stable as a molecule with little distortion. In that case, the organic compound represented by the general formula (G0) is excellent in carrier transportability and reliability and can be said to be a suitable molecule for a light-emitting element.

Further, when MS / MS analysis was performed on the organic compound represented by the general formula (G0), the fragment ion obtained by ionizing the structure represented by the following general formula (g1) together with the fragment ion obtained by ionizing the structure represented by the general formula (g0) Are preferably detected simultaneously. The fragment ion in which the structure represented by the general formula (g1) is ionized is, similarly to the fragment ion in which the structure represented by the general formula (g0) is ionized, a heteroaromatic hydrocarbon group containing two or more nitrogen atoms (general formula (G0) It is attributed to an ion derived from a structure in which the organic compound is cleaved at the carbon-nitrogen conjugated double bond portion or nitrogen-nitrogen conjugated double bond portion of A). Note that when the general formula (g0) and the general formula (g1) have the same structure, the same MS / MS spectrum may be observed.

In the general formula (g1), Ar _{5 to} Ar ₈ each independently represents a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 25 carbon atoms, and m _{1 to} m ₄ represent 0 or 1. , B ₂ represents any one of hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, and carbon ( C on nitrogen and nitrogen (N) represents an unpaired electron.

In the organic compound represented by the general formula (G0), A is a trivalent heteroaromatic hydrocarbon group having 1 to 20 carbon atoms including two or more nitrogen atoms, and has the lowest binding energy in the general formula (G0). It is considered to be a substituent having a linking moiety. The part is considered to be a carbon-nitrogen conjugated bond part. A has at least two carbon-nitrogen conjugate moieties. When the MS / MS analysis was performed in the positive mode for the organic compound represented by the general formula (G0), the fragment ion represented by the general formula (g1) was ionized together with the fragment ion represented by the general formula (g0). When detected, a fragment ion in which the structure represented by the general formula (g0) is ionized is detected. However, the general formula (G0) is greater than when a fragment ion in which the structure represented by the general formula (g1) is ionized is not detected. It can be said that the structure is stable as a molecule with little distortion in the molecular structure. Therefore, the molecule has few unstable parts such as strain, is excellent in carrier transportability and reliability, and can be said to be a molecule suitable for a light-emitting element.

In General Formula (g0) and General Formula (g1), Ar ^{1 to} Ar ⁴ are preferably a substituted or unsubstituted phenyl group. In the case of a phenyl group, since it is thermally and chemically stable, the organic compound estimated from the general formula (g0) and the general formula (g1) is thermally and chemically stable. It can be said that it is an organic compound with excellent properties.

Note that in General Formulas (G0) to (G5), Ar ^{1 to} Ar ¹² are preferably substituted or unsubstituted phenylene groups. In the case of a phenylene group, since it is thermally and chemically stable and can easily increase the molecular weight, an organic compound having excellent reliability and heat resistance can be obtained. When the organic compound has a plurality of phenyl groups, the bonding position is preferably a meta position. By using a meta bond, a high T1 level can be obtained, and a light-emitting element with high emission efficiency can be obtained.

In addition, it is preferable from the viewpoint of carrier transportability that the fragment ion in which the structure represented by the general formula (g0) is ionized is any one of the following structural formulas (100) to (103). In this case, the organic compound represented by the general formula (G0) includes one phenyl group in A which is a heteroaromatic hydrocarbon group having 1 to 20 carbon atoms including two or more nitrogen atoms in the general formula (G0). One or two bonded structures. In this case, in the case of a phenyl group, since it is electrochemically stable and can easily increase the molecular weight, the organic compound represented by the general formula (G0) should be an organic compound having excellent reliability and heat resistance. it can.

In addition, the organic compound represented by the general formula (G0) is preferably an organic compound represented by the following general formula (G1). The organic compound represented by the general formula (G1) has a structure in which one phenyl group is bonded to A in the general formula (G0). Since the phenyl group is electrochemically stable, an organic compound having excellent reliability can be obtained.

In General Formula (G1), A represents a heteroaromatic hydrocarbon group having 1 to 20 carbon atoms containing two or more substituted or unsubstituted nitrogen atoms, and Ar ^{5 to} Ar ¹² are each independently substituted or unsubstituted. Represents an aromatic hydrocarbon group having 6 to 25 carbon atoms, m ^{1 to} m ⁴ and l ^{1 to} l ⁴ each independently represents 0 or 1, and B ² and B ³ each independently represent hydrogen, substituted or non-substituted It represents any one of a substituted aromatic hydrocarbon group having 6 to 25 carbon atoms or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms.

In addition, when MS / MS analysis is performed in a positive mode on the EL layer of the light-emitting element having the organic compound represented by the general formula (G1), fragment ions belonging to the structural formula (100) are detected. preferable. When fragment ions in which the structure represented by the structural formula (100) is ionized are detected, it can be said that the organic compound represented by the general formula (G1) has a stable structure as a molecule with little distortion in the molecular structure. Therefore, it can be said that the molecule is excellent in carrier transportability and reliability and is suitable for a light-emitting element.

In addition, the organic compound represented by the general formula (G0) is preferably an organic compound represented by the following general formula (G2) or (G3). The organic compound represented by the general formula (G2) or (G3) represents an organic compound in which A in the general formula (G0) is any one of a triazine ring, a pyrimidine ring, an imidazole ring, and a triazole ring. Such a heterocyclic ring has a high T1 level, a high electron transporting property, and is electrochemically stable. Therefore, when an organic compound having such a structure is used for a light-emitting element, high light emission is achieved. A light-emitting element having efficiency, a low driving voltage, and good reliability can be provided. In particular, A is preferably a 6-membered ring because the electrochemical stability is superior to that of a 5-membered ring.

In General Formulas (G2) and (G3), Ar ^{1 to} Ar ¹² each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, and n ^{1 to} n ⁴ and m ^{1 to} m ⁴ , And l ^{1 to} l ⁴ each independently represents 0 or 1, and B ^{1 to} B ³ each independently represent hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, a substituted or unsubstituted group 1 represents a heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, and Q represents carbon or nitrogen. In addition, when Q is carbon, Q may have a substituent. When Q is carbon and has no substituent, Q represents CH.

In addition, as described above, when an organic compound represented by the general formula (G2) or (G3) is subjected to MS / MS analysis in the positive mode, fragment ions in which the structure represented by the general formula (g0) is ionized are detected. The organic compound represented by the general formula (G2) or (G3) has a stable structure as a molecule with little distortion in the molecular structure. Therefore, it can be said that the molecule is excellent in carrier transportability and reliability and is suitable for a light-emitting element.

In addition, as described above, when the MS / MS analysis was performed in the positive mode on the organic compound represented by the general formula (G2) or (G3), the structure represented by the general formula (g0) When an MS spectrum of a fragment ion in which the structure represented by the formula (g1) is ionized is detected, a fragment ion in which the structure represented by the general formula (g0) is ionized is observed, but the structure represented by the general formula (g1) is ionized. It can be said that the organic compound represented by the general formula (G2) or (G3) has a stable structure as a molecule with less distortion in the molecular structure than in the case where no fragment ions are observed. Therefore, it can be said that the molecule is excellent in carrier transportability and reliability and is suitable for a light-emitting element.

In addition, the organic compound represented by the general formula (G0) is preferably an organic compound represented by any one of the following general formulas (G4) and (G5). The organic compound represented by the general formula (G4) or (G5) has a phenyl group on a hetero 6-membered ring or a hetero 5-membered ring containing two or three nitrogen atoms in the general formula (G2) or (G3). It has a combined structure. Since the phenyl group is electrochemically stable, an organic compound having excellent reliability can be obtained.

In General Formulas (G4) and (G5), Ar ^{5 to} Ar ¹² each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, m ^{1 to} m ⁴ , l ^{1 to} l ^4. Each independently represents 0 or 1, and B ² and B ³ each independently represent hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted carbon atom having 1 to 20 carbon atoms. Any one of the above heteroaromatic hydrocarbon groups, and Q represents carbon or nitrogen. In addition, when Q is carbon, Q may have a substituent. When Q is carbon and has no substituent, Q represents CH.

When the EL layer of the light-emitting element having the organic compound represented by the general formula (G4) or (G5) is dissolved in a suitable solvent and subjected to MS / MS analysis, the structure represented by the structural formula (100) is Preferably, ionized fragments are detected. When fragment ions in which the structure represented by the structural formula (100) is ionized are detected, the organic compound represented by the general formula (G3) can be said to have a stable structure as a molecule with little distortion in the molecule. Therefore, it can be said that the molecule is excellent in carrier transportability and reliability and is suitable for a light-emitting element. In addition, when the fragment ion which the structure shown to Structural formula (100) ionized is detected, it detects in m / z = 104 vicinity.

When the EL layer of the light-emitting element having the organic compound represented by the general formula (G0) is dissolved in an appropriate solvent and subjected to MS / MS analysis, the structure represented by the general formula (g0) is attributed to the ionized fragment. It is preferable that the intensity of the fragment ion spectrum detected is 100 times or more higher than the intensity of the precursor ion spectrum detected simultaneously. Fragments detected with such an intensity may be seen when the triazine ring is cleaved. In other words, when a fragment ion spectrum is obtained with an intensity of 100 times or more compared to the intensity of the detected precursor ion spectrum, the organic compound subjected to MS / MS analysis contains a triazine ring. There is. As described above, the triazine ring has a high T1 level, a high electron transport property, and is electrochemically stable. Therefore, by using an organic compound having a triazine ring for a light-emitting element, high emission efficiency can be obtained. Accordingly, a light-emitting element having a low driving voltage and good reliability can be provided.

The molecular weight of the organic compound represented by the general formula (G0) is preferably 300 to 1000. By setting it as such molecular weight, since it can be set as the organic compound excellent in sublimation property, it is useful for preparation of the light emitting element using vacuum evaporation. Moreover, it can be set as the organic compound excellent also in heat resistance.

In addition, it is preferable that at least one of B ² and B ^{3 in} the general formulas (G0) to (G5) has a substituted or unsubstituted benzofuran skeleton or benzothiophene skeleton. With the above structure, the organic compound can have improved heat resistance while having a high T1 level.

<Method of performing MS / MS analysis on EL layer of light-emitting element>
A method for performing MS / MS analysis on the EL layer of the light-emitting element will be described below with reference to FIGS. 2A to 2C illustrate a method for preparing a sample for MS / MS analysis by eluting the EL layer in a desired solvent. However, the sample preparation method for MS / MS analysis is not limited to the following examples. .

FIG. 2A is a schematic cross-sectional view illustrating a light-emitting element of one embodiment of the present invention. In FIG. 2, portions having the same functions as those shown in FIG. 1 may have the same hatch patterns and may be omitted. Moreover, the same code | symbol is attached | subjected to the location which has the same function, and the detailed description may be abbreviate | omitted.

FIG. 2A is a schematic cross-sectional view of the light-emitting element 152 of one embodiment of the present invention.

The light-emitting element 152 includes a pair of electrodes (the electrode 101 and the electrode 102) between a pair of substrates (the substrate 200 and the substrate 220), and the EL layer 100 provided between the pair of electrodes. The EL layer 100 includes at least a light emitting layer 130.

Note that the structure of the light-emitting element 150 may be referred to for other structures of the light-emitting element 152.

In order to perform an MS / MS analysis on the EL layer of this light-emitting element, first, as shown in FIG. 2A, the substrate of the light-emitting element 152 is peeled off or the sealing is cut, and the EL layer 180 including the electrode. Need to be exposed. Although FIG. 2A shows an example in which the substrate on the cathode side is peeled, the method for exposing the EL layer is not limited to this. For example, the substrate on the anode side may be peeled off, or the substrate on either the cathode side or the cathode side may be cut.

Next, as shown in FIG. 2B, the EL layer 180 including the exposed electrode is placed in a desired solvent 310 in a container 300, and the organic compound used in the EL layer 100 is dissolved by stirring. And prepare a sample for MS / MS analysis. As the solvent 310, an organic solvent in which the organic compound used in the EL layer 100 can be dissolved is preferable. For example, ethanol, methanol, chloroform, dichloromethane, toluene, acetone, ethyl acetate, acetonitrile, or a mixed solvent thereof can be used. The solvent 310 is not limited to these.

The sample 320 having an organic compound contained in the EL layer 100 is prepared (see FIG. 2C) by separating the solid in the prepared solution from unnecessary substances by filtration, decantation, or the like. By performing MS / MS analysis on the sample 320 thus obtained, information on the organic material in the EL layer can be obtained. In addition, since it becomes easy to isolate | separate and refine | purify a target object by making it melt | dissolve in a solution, an analysis precision can be improved.

In addition, although the sample adjustment in the solution state which melt | dissolved EL layer was demonstrated above, the sample adjustment method is not restricted to this. For example, when ionization is performed by a matrix-assisted laser desorption ionization method (Matrix-Assisted Laser Desorption / Ionization: MALDI), measurement is performed by simply cutting off the sealing of the light emitting element 152 and exposing the EL layer 180 including the electrode. be able to.

Here, MS / MS analysis (tandem mass spectrometry) will be described. MS / MS analysis is an analysis technique in which an organic compound to be measured is ionized, and energy is applied to the ionized organic compound in a collision cell for cleavage to detect secondary ions (product ions). The product ion is an ion obtained by cleaving the target organic compound once or multiple times.

Examples of the method for cleaving the ionized organic compound include collision-induced dissociation (CID) and post-source decay (PSD). The method of cleaving the ionized organic compound is not limited to this. An inert gas can be suitably used for collision-induced dissociation. Examples of the inert gas include nitrogen, helium, neon, argon, krypton, xenon and the like.

Examples of ionization include an electrospray method (ESI), an electron ionization method (EI), a chemical ionization method (CI), and MALDI. However, the ion method is not limited to this.

MS / MS analysis is a method suitable for analyzing an organic compound in an EL layer of a light-emitting element because it can be measured in a very small amount, has high sensitivity, and can be measured even in a mixture. Further, since the fragment ion has information on a binding portion having a relatively low binding energy in the molecular structure to be measured, the molecular structure can be analyzed by analyzing the fragment ion.

Depending on the MS / MS analysis device, the accelerating voltage of the inert gas used to cleave the organic compound may be different, and the unit has a value unique to the device called Normalized Collation Energy (NCE). May be used. In this case, by using an acceleration voltage corresponding to the NCE of each device (for example, converting NCE into eV units), similar results can be obtained even in different devices.

Here, when the MS / MS analysis was performed on the EL layer of the light-emitting element with favorable characteristics, the present inventors observed a fragment having a C═N bond represented by the general formula (G1). In this case, the organic compound molecule to be measured has at least a conjugated double bond in the order of nitrogen-carbon-nitrogen represented by the following general formula (G8). It has been found that the carbon atom has a structure having an aryl group. Examples of the skeleton having a conjugated double bond in the order of nitrogen-carbon-nitrogen include a pyrimidine skeleton, a triazine skeleton, a triazole skeleton, and an imidazole skeleton. That is, when a fragment having a cyano group as represented by the general formula (g0) is observed, an organic compound that is a measurement target of MS / MS analysis is a pyrimidine skeleton, a triazine skeleton, a triazole skeleton, an imidazole in the molecule. One or more of the skeletons may be included.

In General Formula (G8), Ar represents an aromatic hydrocarbon group, a heteroaromatic compound, or a combination thereof. Examples of the aromatic hydrocarbon group include a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, specifically, a substituted or unsubstituted phenyl group, biphenyl group, naphthyl group, and fluorenyl group. . Examples of the heteroaromatic compounds include substituted or unsubstituted heteroaromatic compounds having 1 to 25 carbon atoms, specifically, substituted or unsubstituted pyridinenyl groups, pyrimidinyl groups, pyrazinyl groups, triazinyl groups, carbazolyl groups, dibenzofurans. Nyl group, dibenzothiophenyl group, benzonaphthofuranyl group, benzonaphthothiophenyl group, dibenzoquinoxalinyl group, dibenzoquinazolinyl group, imidazolyl group, triazolyl group and the like. Ar is not limited to the above example.

<Material>
Next, details of components of the light-emitting element according to one embodiment of the present invention are described below.

≪Luminescent layer≫
The light-emitting layer 130 preferably includes at least a host material 131 and further includes a guest material 132. The host material 131 may include an organic compound 131_1 and an organic compound 131_2. In the light emitting layer 130, the host material 131 is present in the largest amount by weight, and the guest material 132 is dispersed in the host material 131. When the guest material 132 is a fluorescent compound, the S1 level of the host material 131 (the organic compound 131_1 and the organic compound 131_2) of the light-emitting layer 130 is higher than the S1 level of the guest material (guest material 132) of the light-emitting layer 130. It is preferable. Further, when the guest material 132 is a phosphorescent compound, the T1 level of the host material 131 (the organic compound 131_1 and the organic compound 131_2) of the light-emitting layer 130 is higher than the T1 level of the guest material (guest material 132) of the light-emitting layer 130. Is preferably high.

The organic compound 131_1 preferably has a heteroaromatic skeleton having 1 to 20 carbon atoms containing two or more nitrogen atoms. In particular, a compound having a pyrimidine skeleton and a triazine skeleton is preferable. As the organic compound 131_1, a material having an electron transport property higher than that of holes (electron transport material) can be used, and the material has an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher. preferable.

Specifically, for example, 4,6-bis [3- (phenanthrene-9-yl) phenyl] pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis [3- (4-dibenzothienyl) phenyl] pyrimidine A heterocyclic compound having a diazine skeleton such as (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis [3- (9H-carbazol-9-yl) phenyl] pyrimidine (abbreviation: 4,6mCzP2Pm); {4- [3- (N-phenyl-9H-carbazol-3-yl) -9H-carbazol-9-yl] phenyl} -4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2- {3- [3- (benzo [b] naphtho [1,2-d] furan-8-yl) phenyl] phenyl} -4,6-diphenyl-1,3,5-tria (Abbreviation: mBnfBPTzn), 2,4,6-tris (biphenyl-3-yl) -1,3,5-triazine (abbreviation: T2T), 2,4,6-tris [3 ′-(pyridine-3 -Yl) -biphenyl-3-yl] -1,3,5-triazine (abbreviation: TmPPPyTz), 1- (4- (9H-carbazol-9-yl) -phenyl-1-yl) -2,4- A heterocyclic compound having a triazine skeleton, a pyrimidine skeleton, or a triazole skeleton such as biphenyl-1,2,4-1H-triazole (abbreviation: CzTAZ (1H)) is preferable because it is stable and reliable. In addition, the heterocyclic compound having the skeleton has a high electron transporting property and contributes to a reduction in driving voltage. The substances mentioned here are mainly substances having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher. Note that other than the above substances, any substance that has a property of transporting more electrons than holes may be used.

As the organic compound 131_1, compounds such as a pyridine derivative, a pyrazine derivative, a pyridazine derivative, a bipyridine derivative, a quinoxaline derivative, a dibenzoquinoxaline derivative, a phenanthroline derivative, and a purine derivative can also be used. Such an organic compound is preferably a material having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher.

Specifically, for example, heterocyclic compounds having a pyridine skeleton such as bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), and 2- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f , H] quinoxaline (abbreviation: 2mDBTPDBq-II), 2- [3 ′-(dibenzothiophen-4-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (abbreviation: 2mDBTPBPDBq-II), 2- [ 3 ′-(9H-carbazol-9-yl) biphenyl-3-yl] dibenzo [f, h] quinoxaline (abbreviation: 2mCzBPDBq), 2- [4- (3,6-diphenyl-9H-carbazol-9-yl) ) Phenyl] dibenzo [f, h] quinoxaline (abbreviation: 2CzPDBq-III), 7- [3- (dibe Zothiophen-4-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 7mDBTPDBq-II) and 6- [3- (dibenzothiophen-4-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 6mDBTPDBq-II), 2- [3- (3,9′-bi-9H-carbazol-9-yl) phenyl] dibenzo [f, h] quinoxaline (abbreviation: 2mCzCzPDBq) and other heteroaromatic rings having a pyrazine skeleton Compounds, 3,5-bis [3- (9H-carbazol-9-yl) phenyl] pyridine (abbreviation: 35DCzPPy), 1,3,5-tri [3- (3-pyridyl) phenyl] benzene (abbreviation: TmPyPB) A heterocyclic compound having a pyridine skeleton such as) can also be used. In addition, poly (2,5-pyridinediyl) (abbreviation: PPy), poly [(9,9-dihexylfluorene-2,7-diyl) -co- (pyridine-3,5-diyl)] (abbreviation: PF -Py), poly [(9,9-dioctylfluorene-2,7-diyl) -co- (2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy) Molecular compounds can also be used. Note that other than the above substances, any substance that has a property of transporting more electrons than holes may be used.

The organic compound 131_2 preferably has a C 1-20 heteroaromatic skeleton containing two or more nitrogen atoms. A nitrogen-containing hetero five-membered ring skeleton is particularly preferable. Examples thereof include an imidazole skeleton, a triazole skeleton, and a tetrazole skeleton. As the organic compound 131_2, a material having a property of transporting more holes than electrons (a hole transporting material) can be used, and a material having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or more. It is preferable that The hole transporting material may be a polymer compound.

Specifically, for example, 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole (abbreviation: TAZ), 9- [4- (4 , 5-Diphenyl-4H-1,2,4-triazol-3-yl) phenyl] -9H-carbazole (abbreviation: CzTAZ1), 2,2 ′, 2 ″-(1,3,5-benzenetriyl ) Tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2- [3- (dibenzothiophen-4-yl) phenyl] -1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), etc. Can be used.

As the organic compound 131_2, other compounds having a nitrogen-containing five-membered heterocyclic skeleton or a tertiary amine skeleton can also be preferably used. Specific examples include a pyrrole skeleton or an aromatic amine skeleton. For example, indole derivatives, carbazole derivatives, triarylamine derivatives, and the like can be given. As the organic compound 131_2, a material having a property of transporting more holes than electrons (a hole transporting material) can be used, and a material having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or more. It is preferable that The hole transporting material may be a polymer compound.

As these materials having a high hole transporting property, specifically, as an aromatic amine compound, N, N′-di (p-tolyl) -N, N′-diphenyl-p-phenylenediamine (abbreviation: DTDPPA) 4,4′-bis [N- (4-diphenylaminophenyl) -N-phenylamino] biphenyl (abbreviation: DPAB), N, N′-bis {4- [bis (3-methylphenyl) amino] phenyl } -N, N′-diphenyl- (1,1′-biphenyl) -4,4′-diamine (abbreviation: DNTPD), 1,3,5-tris [N- (4-diphenylaminophenyl) -N— Phenylamino] benzene (abbreviation: DPA3B) and the like.

As the carbazole derivative, specifically, 3- [N- (4-diphenylaminophenyl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis [N- ( 4-diphenylaminophenyl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis [N- (4-diphenylaminophenyl) -N- (1-naphthyl) amino] -9 -Phenylcarbazole (abbreviation: PCzTPN2), 3- [N- (9-phenylcarbazol-3-yl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis [N- ( 9-phenylcarbazol-3-yl) -N-phenylamino] -9-phenylcarbazole (abbreviation: PCzPCA) ), 3- [N- (1- naphthyl)-N-(9-phenyl-3-yl) amino] -9-phenylcarbazole (abbreviation: PCzPCN1), and the like.

As other carbazole derivatives, 4,4′-di (N-carbazolyl) biphenyl (abbreviation: CBP), 1,3,5-tris [4- (N-carbazolyl) phenyl] benzene (abbreviation: TCPB) ), 9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: CzPA), 1,4-bis [4- (N-carbazolyl) phenyl] -2,3,5, 6-tetraphenylbenzene or the like can be used.

N, N-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazol-3-amine (abbreviation: CzA1PA), 4- (10-phenyl-9-anthryl) tri Phenylamine (abbreviation: DPhPA), 4- (9H-carbazol-9-yl) -4 '-(10-phenyl-9-anthryl) triphenylamine (abbreviation: YGAPA), N, 9-diphenyl-N- [ 4- (10-phenyl-9-anthryl) phenyl] -9H-carbazol-3-amine (abbreviation: PCAPA), N, 9-diphenyl-N- {4- [4- (10-phenyl-9-anthryl) Phenyl] phenyl} -9H-carbazol-3-amine (abbreviation: PCAPBA), N, 9-diphenyl-N- (9,10-diphenyl-2-ant ) -9H-carbazol-3-amine (abbreviation: 2PCAPA), 9-phenyl-3- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: PCzPA), 3,6- Diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: DPCzPA), N, N, N ′, N ′, N ″, N ″, N ′ ″ , N ′ ″-octaphenyldibenzo [g, p] chrysene-2,7,10,15-tetraamine (abbreviation: DBC1) and the like can be used.

In addition, poly (N-vinylcarbazole) (abbreviation: PVK), poly (4-vinyltriphenylamine) (abbreviation: PVTPA), poly [N- (4- {N ′-[4- (4-diphenylamino)] Phenyl] phenyl-N′-phenylamino} phenyl) methacrylamide] (abbreviation: PTPDMA), poly [N, N′-bis (4-butylphenyl) -N, N′-bis (phenyl) benzidine] (abbreviation: Polymer compounds such as Poly-TPD can also be used.

Further, as a material having a high hole transporting property, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB or α-NPD), N, N′— Bis (3-methylphenyl) -N, N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviation: TPD), 4,4 ′, 4 ″ -tris (carbazole-9) -Yl) triphenylamine (abbreviation: TCTA), 4,4 ′, 4 ″ -tris [N- (1-naphthyl) -N-phenylamino] triphenylamine (abbreviation: 1′-TNATA), 4, 4 ′, 4 ″ -tris (N, N-diphenylamino) triphenylamine (abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] Triphenylamine (abbreviation: TDATA), 4,4′-bis [N- (spiro-9,9′-bifluoren-2-yl) -N-phenylamino] biphenyl (abbreviation: BSPB), 4-phenyl-4 ′-(9-phenyl) Fluoren-9-yl) triphenylamine (abbreviation: BPAFLP), 4-phenyl-3 ′-(9-phenylfluoren-9-yl) triphenylamine (abbreviation: mBPAFLP), N- (9,9-dimethyl- 9H-Fluoren-2-yl) -N- {9,9-dimethyl-2- [N′-phenyl-N ′-(9,9-dimethyl-9H-fluoren-2-yl) amino] -9H-fluorene -7-yl} phenylamine (abbreviation: DFLADFL), N- (9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl) diphenylamine (abbreviation: DPNF) ), 2- [N- (4-diphenylaminophenyl) -N-phenylamino] spiro-9,9′-bifluorene (abbreviation: DPASF), 4-phenyl-4 ′-(9-phenyl-9H-carbazole-) 3-yl) triphenylamine (abbreviation: PCBA1BP), 4,4′-diphenyl-4 ″-(9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBBi1BP), 4- (1 -Naphthyl) -4 '-(9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBBANB), 4,4'-di (1-naphthyl) -4' '-(9-phenyl- 9H-carbazol-3-yl) triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl- (9-phenyl-9H-carbazol-3-yl) a (Abbreviation: PCA1BP), N, N′-bis (9-phenylcarbazol-3-yl) -N, N′-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N, N ′, N ′ '-Triphenyl-N, N', N ''-tris (9-phenylcarbazol-3-yl) benzene-1,3,5-triamine (abbreviation: PCA3B), N- (4-biphenyl) -N- (9,9-dimethyl-9H-fluoren-2-yl) -9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N- (1,1′-biphenyl-4-yl) -N— [4- (9-phenyl-9H-carbazol-3-yl) phenyl] -9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), 9,9-dimethyl-N-phenyl-N- [4- (9 Phenyl-9H-carbazol-3-yl) phenyl] fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N- [4- (9-phenyl-9H-carbazol-3-yl) phenyl] spiro-9 , 9′-bifluoren-2-amine (abbreviation: PCBASF), 2- [N- (9-phenylcarbazol-3-yl) -N-phenylamino] spiro-9,9′-bifluorene (abbreviation: PCASF), 2,7-bis [N- (4-diphenylaminophenyl) -N-phenylamino] spiro-9,9′-bifluorene (abbreviation: DPA2SF), N- [4- (9H-carbazol-9-yl) phenyl ] -N- (4-phenyl) phenylaniline (abbreviation: YGA1BP), N, N′-bis [4- (carbazol-9-yl) phenyl] -N, N An aromatic amine compound such as' -diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F) can be used. 3- [4- (1-naphthyl) -phenyl] -9-phenyl-9H-carbazole (abbreviation: PCPN), 3- [4- (9-phenanthryl) -phenyl] -9-phenyl-9H-carbazole (Abbreviation: PCPPn), 3,3′-bis (9-phenyl-9H-carbazole) (abbreviation: PCCP), 1,3-bis (N-carbazolyl) benzene (abbreviation: mCP), 3,6-bis ( 3,5-diphenylphenyl) -9-phenylcarbazole (abbreviation: CzTP), 3,6-di (9H-carbazol-9-yl) -9-phenyl-9H-carbazole (abbreviation: PhCzGI), 2,8- An amine compound such as di (9H-carbazol-9-yl) -dibenzothiophene (abbreviation: Cz2DBT), a carbazole compound, or the like can be used. Among the compounds described above, a compound having a pyrrole skeleton or an aromatic amine skeleton is preferable because it is stable and reliable. In addition, the compound having the skeleton has a high hole transport property and contributes to a reduction in driving voltage.

In the light-emitting layer 130, the guest material 132 is not particularly limited. Examples of the fluorescent compound include anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarins. Derivatives, phenoxazine derivatives, phenothiazine derivatives, and the like are preferable. For example, the following substances can be used.

Specifically, 5,6-bis [4- (10-phenyl-9-anthryl) phenyl] -2,2′-bipyridine (abbreviation: PAP2BPy), 5,6-bis [4 ′-(10-phenyl) -9-anthryl) biphenyl-4-yl] -2,2'-bipyridine (abbreviation: PAPP2BPy), N, N'-diphenyl-N, N'-bis [4- (9-phenyl-9H-fluorene-9 -Yl) phenyl] pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N, N′-bis (3-methylphenyl) -N, N′-bis [3- (9-phenyl-9H-fluorene) -9-yl) phenyl] pyrene-1,6-diamine (abbreviation: 1,6 mM emFLPAPrn), N, N′-bis [4- (9-phenyl-9H-fluoren-9-yl) phenyl] -N, N '-Bi (4-tert-Butylphenyl) -pyrene-1,6-diamine (abbreviation: 1,6tBu-FLPAPrn), N, N′-bis [4- (9-phenyl-9H-fluoren-9-yl) phenyl] -N, N'-diphenyl-3,8-dicyclohexylpyrene-1,6-diamine (abbreviation: ch-1,6FLPAPrn), N, N'-bis [4- (9H-carbazol-9-yl) phenyl] -N, N'-diphenylstilbene-4,4'-diamine (abbreviation: YGA2S), 4- (9H-carbazol-9-yl) -4 '-(10-phenyl-9-anthryl) triphenylamine (abbreviation) : YGAPA), 4- (9H-carbazol-9-yl) -4 ′-(9,10-diphenyl-2-anthryl) triphenylamine (abbreviation: 2YGAPPA), , 9-diphenyl-N- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazol-3-amine (abbreviation: PCAPA), perylene, 2,5,8,11-tetra (tert-butyl) ) Perylene (abbreviation: TBP), 4- (10-phenyl-9-anthryl) -4 ′-(9-phenyl-9H-carbazol-3-yl) triphenylamine (abbreviation: PCBAPA), NN ″ -(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene) bis [N, N ', N'-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N, 9 -Diphenyl-N- [4- (9,10-diphenyl-2-anthryl) phenyl] -9H-carbazol-3-amine (abbreviation: 2PCAPPA), N- [4- ( 9,10-diphenyl-2-anthryl) phenyl] -N, N ′, N′-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), N, N, N ′, N ′, N ″, N ″, N ′ ″, N ′ ″-octaphenyldibenzo [g, p] chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), coumarin 30, N- (9,10-diphenyl) -2-anthryl) -N, 9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), N- [9,10-bis (1,1′-biphenyl-2-yl) -2-anthryl] -N, 9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N- (9,10-diphenyl-2-anthryl) -N, N ', N'-triphenyl-1,4-phenylene Zia (Abbreviation: 2DPAPA), N- [9,10-bis (1,1′-biphenyl-2-yl) -2-anthryl] -N, N ′, N′-triphenyl-1,4-phenylenediamine (Abbreviation: 2DPABPhA), 9,10-bis (1,1′-biphenyl-2-yl) -N- [4- (9H-carbazol-9-yl) phenyl] -N-phenylanthracen-2-amine ( Abbreviation: 2YGABPhA), N, N, 9-triphenylanthracene-9-amine (abbreviation: DPhAPhA), coumarin 6, coumarin 545T, N, N′-diphenylquinacridone (abbreviation: DPQd), rubrene, 2,8-di -Tert-butyl-5,11-bis (4-tert-butylphenyl) -6,12-diphenyltetracene (abbreviation: TBRb), Nile Red, 5, 2-bis (1,1′-biphenyl-4-yl) -6,11-diphenyltetracene (abbreviation: BPT), 2- (2- {2- [4- (dimethylamino) phenyl] ethenyl} -6- Methyl-4H-pyran-4-ylidene) propanedinitrile (abbreviation: DCM1), 2- {2-methyl-6- [2- (2,3,6,7-tetrahydro-1H, 5H-benzo [ij] Quinolizin-9-yl) ethenyl] -4H-pyran-4-ylidene} propanedinitrile (abbreviation: DCM2), N, N, N ′, N′-tetrakis (4-methylphenyl) tetracene-5,11-diamine (Abbreviation: p-mPhTD), 7,14-diphenyl-N, N, N ′, N′-tetrakis (4-methylphenyl) acenaphtho [1,2-a] fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2- {2-isopropyl-6- [2- (1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolidine-9. -Yl) ethenyl] -4H-pyran-4-ylidene} propanedinitrile (abbreviation: DCJTI), 2- {2-tert-butyl-6- [2- (1,1,7,7-tetramethyl-2) , 3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolizin-9-yl) ethenyl] -4H-pyran-4-ylidene} propanedinitrile (abbreviation: DCJTB), 2- (2,6- Bis {2- [4- (dimethylamino) phenyl] ethenyl} -4H-pyran-4-ylidene) propanedinitrile (abbreviation: BisDCM), 2- {2,6-bis [2- (8-methoxy-1) , 1,7,7 Tetramethyl-2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolizin-9-yl) ethenyl] -4H-pyran-4-ylidene} propanedinitrile (abbreviation: BisDCJTM), 5,10 , 15,20-tetraphenylbisbenzo [5,6] indeno [1,2,3-cd: 1 ′, 2 ′, 3′-lm] perylene (abbreviation: DBP), and the like.

Examples of the guest material 132 (phosphorescent compound) include iridium, rhodium, or platinum-based organometallic complexes, or metal complexes. Among these, organic iridium complexes such as iridium-based orthometal complexes are preferable. Examples of orthometalated ligands include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, and isoquinoline ligands. Can be mentioned. Examples of the metal complex include a platinum complex having a porphyrin ligand.

As a substance having an emission peak in blue or green, for example, tris {2- [5- (2-methylphenyl) -4- (2,6-dimethylphenyl) -4H-1,2,4-triazole-3 -Yl-κN ² ] phenyl-κC} iridium (III) (abbreviation: Ir (mppptz-dmp) ₃ ), tris (5-methyl-3,4-diphenyl-4H-1,2,4-triazolate) iridium ( III) (abbreviation: Ir (Mptz) ₃ ), tris [4- (3-biphenyl) -5-isopropyl-3-phenyl-4H-1,2,4-triazolato] iridium (III) (abbreviation: Ir (iPrptz) _-3b) 3), tris [3- (5-biphenyl) -5-isopropyl-4-phenyl-4H-1,2,4-triazolato] iridium (III) (abbreviation: I _{(IPr5btz) 3),} 4H- or organometallic iridium complex having a triazole skeleton, such as tris [3-methyl-1- (2-methylphenyl) -5-phenyl-1H-1,2,4-triazolato] Iridium (III) (abbreviation: Ir (Mptz1-mp) ₃ ), tris (1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato) iridium (III) (abbreviation: Ir (Prptz1) -Me) ₃ ) an organometallic iridium complex having a 1H-triazole skeleton, fac-tris [1- (2,6-diisopropylphenyl) -2-phenyl-1H-imidazole] iridium (III) (abbreviation: Ir (iPrpmi) ₃ ), tris [3- (2,6-dimethylphenyl) -7-methylimidazo [1,2-f] Organometallic iridium complexes having an imidazole skeleton such as phenanthridinato] iridium (III) (abbreviation: Ir (dmpimpt-Me) ₃ ), and bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N , C ^{2 ′} ] iridium (III) tetrakis (1-pyrazolyl) borate (abbreviation: FIr6), bis [2- (4 ′, 6′-difluorophenyl) pyridinato-N, C ^{2 ′} ] iridium (III) picolinate ( Abbreviations: FIrpic), bis {2- [3 ′, 5′-bis (trifluoromethyl) phenyl] pyridinato-N, C ^{2 ′} } iridium (III) picolinate (abbreviation: Ir (CF ₃ ppy) ₂ (pic) ), bis [2- (4 ', 6'-difluorophenyl) pyridinato -N, C ^2'] iridium (III) acetyl acetate toner (Abbreviation: FIr (acac)) organometallic iridium complex having a ligand of phenylpyridine derivative having an electron-withdrawing group such as and the like. Among the above-mentioned, organometallic iridium complexes having a nitrogen-containing five-membered heterocyclic skeleton such as a 4H-triazole skeleton, a 1H-triazole skeleton, and an imidazole skeleton have high triplet excitation energy, and have high reliability and luminous efficiency. It is particularly preferred because of its superiority.

Examples of a substance having an emission peak in green or yellow include tris (4-methyl-6-phenylpyrimidinato) iridium (III) (abbreviation: Ir (mppm) ₃ ), tris (4-t-butyl). -6-phenylpyrimidinato) iridium (III) (abbreviation: Ir (tBupppm) ₃ ), (acetylacetonato) bis (6-methyl-4-phenylpyrimidinato) iridium (III) (abbreviation: Ir (mppm) ) ₂ (acac)), (acetylacetonato) bis (6-tert-butyl-4-phenylpyrimidinato) iridium (III) (abbreviation: Ir (tBupppm) ₂ (acac)), (acetylacetonato) bis [4- (2-norbornyl) -6-phenylpyrimidinato] iridium (III) (abbreviation: Ir (nbppm) ₂ (Acac)), (acetylacetonato) bis [5-methyl-6- (2-methylphenyl) -4-phenylpyrimidinato] iridium (III) (abbreviation: Ir (mpmppm) ₂ (acac)), ( Acetylacetonato) bis {4,6-dimethyl-2- [6- (2,6-dimethylphenyl) -4-pyrimidinyl-κN ³ ] phenyl-κC} iridium (III) (abbreviation: Ir (dmppm-dmp) ₂ (acac)), (acetylacetonato) bis (4,6-diphenylpyrimidinato) iridium (III) (abbreviation: Ir (dppm) ₂ (acac)), an organometallic iridium complex having a pyrimidine skeleton, , (Acetylacetonato) bis (3,5-dimethyl-2-phenylpyrazinato) iridium (III) (abbreviation: Ir (mpp Of _{Ir (mppr-iPr) 2 (} acac)): -Me) 2 (acac)), ( acetylacetonato) bis (5-isopropyl-3-methyl-2-phenylpyrazinato) iridium (III) (abbreviation Organometallic iridium complexes having such a pyrazine skeleton, tris (2-phenylpyridinato-N, C ^{2 ′} ) iridium (III) (abbreviation: Ir (ppy) ₃ ), bis (2-phenylpyridinato- N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: Ir (ppy) ₂ (acac)), bis (benzo [h] quinolinato) iridium (III) acetylacetonate (abbreviation: Ir (bzq) ₂ ( acac)), tris (base down zone [h] quinolinato) iridium (III) (abbreviation: Ir _{(bzq) 3),} tris (2-Feniruki Rinato -N, C ^{2 ')} iridium (III) (abbreviation: Ir _(pq) 3), bis (2-phenylquinolinato--N, C ^2') iridium (III) acetylacetonate (abbreviation: Ir (pq) ₂ (acac)), an organometallic iridium complex having a pyridine skeleton, or bis (2,4-diphenyl-1,3-oxazolate-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: Ir ( dpo) ₂ (acac)), bis {2- [4 ′-(perfluorophenyl) phenyl] pyridinato-N, C ^{2 ′} } iridium (III) acetylacetonate (abbreviation: Ir (p-PF-ph) ₂ (acac)), bis (2-phenyl-benzothiazyl Zola DOO -N, C ^{2 ')} iridium (III) acetylacetonate (abbreviation: Ir _(bt) 2 _(aca )) Other organic iridium complex such as tris (acetylacetonato) (monophenanthroline) terbium (III) (abbreviation: rare earth metal complex and the like, such as Tb _(acac) 3 (Phen)). Among the above-described compounds, organometallic iridium complexes having a pyrimidine skeleton are particularly preferable because they are remarkably excellent in reliability and luminous efficiency.

As a substance having an emission peak in yellow or red, for example, (diisobutyrylmethanato) bis [4,6-bis (3-methylphenyl) pyrimidinato] iridium (III) (abbreviation: Ir (5 mdppm) ₂ ( dibm)), bis [4,6-bis (3-methylphenyl) pyrimidinato] (dipivaloylmethanato) iridium (III) (abbreviation: Ir (5 mdppm) ₂ (dpm)), bis [4,6-di (Naphthalen-1-yl) pyrimidinato] (dipivaloylmethanato) iridium (III) (abbreviation: Ir (d1npm) ₂ (dpm)), an organometallic iridium complex having a pyrimidine skeleton, and (acetylacetonato) bis (2,3,5-triphenylpyrazinato) iridium (III) (abbreviation: Ir _(tppr) 2 (ac c)), bis (2,3,5-triphenylpyrazinato) (dipivaloylmethanato) iridium (III) (abbreviation: Ir _(tppr) 2 (dpm)), (acetylacetonato) bis [2 , 3-bis (4-fluorophenyl) quinoxalinato] iridium (III) (abbreviation: Ir (Fdpq) ₂ (acac)), organometallic iridium complexes having a pyrazine skeleton, tris (1-phenylisoquinolinato- N, C ^{2 ′} ) iridium (III) (abbreviation: Ir (piq) ₃ ), bis (1-phenylisoquinolinato-N, C ^{2 ′} ) iridium (III) acetylacetonate (abbreviation: Ir (piq) ₂ In addition to organometallic iridium complexes having a pyridine skeleton such as (acac)), 2,3,7,8,12,13,17,18-octaethyl-2 Platinum complexes such as H, 23H-porphyrin platinum (II) (abbreviation: PtOEP), tris (1,3-diphenyl-1,3-propanedionate) (monophenanthroline) europium (III) (abbreviation: Eu ( DBM) ₃ (Phen)), tris [1- (2-thenoyl) -3,3,3-trifluoroacetonato] (monophenanthroline) europium (III) (abbreviation: Eu (TTA) ₃ (Phen)) Such rare earth metal complexes are mentioned. Among the above-described compounds, organometallic iridium complexes having a pyrimidine skeleton are particularly preferable because they are remarkably excellent in reliability and luminous efficiency. An organometallic iridium complex having a pyrazine skeleton can emit red light with good chromaticity.

The light-emitting material contained in the light-emitting layer 130 is preferably a material that can convert triplet excitation energy into light emission. Examples of the material capable of converting the triplet excitation energy into light emission include a thermally activated delayed fluorescence (TADF) material in addition to a phosphorescent compound. Therefore, the portion described as a phosphorescent compound may be read as a thermally activated delayed fluorescent material. Note that the thermally activated delayed fluorescent material has a small difference between the triplet excitation energy level and the singlet excitation energy level, and the function of converting energy from the triplet excited state to the singlet excited state by crossing between inverses. It is the material which has. Therefore, the triplet excited state can be up-converted (reverse intersystem crossing) into a singlet excited state with a slight thermal energy, and light emission (fluorescence) from the singlet excited state can be efficiently exhibited. As a condition for efficiently obtaining thermally activated delayed fluorescence, the energy difference between the triplet excitation energy level and the singlet excitation energy level is preferably greater than 0 eV but not greater than 0.2 eV, more preferably greater than 0 eV and not greater than 0. 0.1 eV or less.

When the heat activated delayed fluorescent material is composed of one kind of material, for example, the following materials can be used.

First, fullerene and its derivatives, acridine derivatives such as proflavine, eosin and the like can be mentioned. In addition, metal-containing porphyrins including magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), and the like can be given. Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (SnF ₂ (ProtoIX)), a mesoporphyrin-tin fluoride complex (SnF ₂ (Meso IX)), and a hematoporphyrin-tin fluoride complex (SnF _2). (Hemato IX)), coproporphyrin tetramethyl ester-tin fluoride complex (SnF ₂ (Copro III-4Me)), octaethylporphyrin-tin fluoride complex (SnF ₂ (OEP)), etioporphyrin-tin fluoride complex (SnF ₂ (Etio I)), octaethylporphyrin-platinum chloride complex (PtCl ₂ OEP), and the like.

Also, as a thermally activated delayed fluorescent material composed of a kind of material, a heterocyclic compound having a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring can also be used. Specifically, 2- (biphenyl-4-yl) -4,6-bis (12-phenylindolo [2,3-a] carbazol-11-yl) -1,3,5-triazine (abbreviation: PIC-TRZ), 2- {4- [3- (N-phenyl-9H-carbazol-3-yl) -9H-carbazol-9-yl] phenyl} -4,6-diphenyl-1,3,5- Triazine (abbreviation: PCCzPTzn), 2- [4- (10H-phenoxazin-10-yl) phenyl] -4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3- [4 -(5-phenyl-5,10-dihydrophenazin-10-yl) phenyl] -4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3- (9,9-dimethyl- 9H-acridine- 0-yl) -9H-xanthen-9-one (abbreviation: ACRXTN), bis [4- (9,9-dimethyl-9,10-dihydroacridine) phenyl] sulfone (abbreviation: DMAC-DPS), 10-phenyl -10H, 10'H-spiro [acridine-9,9'-anthracene] -10'-one (abbreviation: ACRSA) and the like. Since the heterocyclic compound has a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring, it is preferable because of its high electron transporting property and hole transporting property. Among these, among skeletons having a π-electron deficient heteroaromatic ring, a diazine skeleton (pyrimidine skeleton, pyrazine skeleton, pyridazine skeleton) or a triazine skeleton is preferable because it is stable and has high reliability. Among skeletons having a π-electron rich heteroaromatic ring, an acridine skeleton, a phenoxazine skeleton, a thiophene skeleton, a furan skeleton, and a pyrrole skeleton are stable and reliable. It is preferable to have one or more. As the pyrrole skeleton, an indole skeleton, a carbazole skeleton, and a 3- (9-phenyl-9H-carbazol-3-yl) -9H-carbazole skeleton are particularly preferable. A substance in which a π-electron rich heteroaromatic ring and a π-electron deficient heteroaromatic ring are directly bonded has both a donor property of a π-electron rich heteroaromatic ring and an acceptor property of a π-electron deficient heteroaromatic ring, This is particularly preferable because the difference between the energy level in the singlet excited state and the energy level in the triplet excited state is small.

Further, the light emitting layer 130 may have a material other than the host material 131 and the guest material 132.

A material that can be used for the light-emitting layer 130 is not particularly limited, and examples thereof include condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo [g, p] chrysene derivatives. Specifically, 9,10-diphenylanthracene (abbreviation: DPAnth), 6,12-dimethoxy-5,11-diphenylchrysene, 9,10-bis (3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di (2-naphthyl) anthracene (abbreviation: t-BuDNA), 9,9′- Bianthryl (abbreviation: BANT), 9,9 ′-(stilbene-3,3′-diyl) diphenanthrene (abbreviation: D) NS), 9,9 ′-(stilbene-4,4′-diyl) diphenanthrene (abbreviation: DPNS2), 1,3,5-tri (1-pyrenyl) benzene (abbreviation: TPB3), and the like. . In addition, one or more kinds of substances having a singlet excitation energy level or a triplet excitation energy level higher than the excitation energy level of the guest material 132 may be selected from these and known substances and used. .

Further, for example, a compound having a heteroaromatic skeleton such as an oxadiazole derivative can be used for the light-emitting layer 130. Specifically, for example, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis [5- (P-tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 9- [4- (5-phenyl-1,3,4-oxadi) Heterocyclic compounds such as (azol-2-yl) phenyl] -9H-carbazole (abbreviation: CO11) and 4,4′-bis (5-methylbenzoxazol-2-yl) stilbene (abbreviation: BzOs).

In addition, a metal complex having a heterocyclic ring (eg, zinc and aluminum-based metal complex) or the like can be used for the light-emitting layer 130. For example, a metal complex having a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand can be given. Specifically, for example, tris (8-quinolinolato) aluminum (III) (abbreviation: Alq), tris (4-methyl-8-quinolinolato) aluminum (III) (abbreviation: Almq ₃ ), bis (10-hydroxybenzo) [H] quinolinato) beryllium (II) (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (III) (abbreviation: BAlq), bis (8-quinolinolato) zinc (II) (abbreviation: Znq) and the like include metal complexes having a quinoline skeleton or a benzoquinoline skeleton. In addition, bis [2- (2-benzoxazolyl) phenolato] zinc (II) (abbreviation: ZnPBO), bis [2- (2-benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ), etc. A metal complex having an oxazole-based or thiazole-based ligand can also be used.

In addition, the light emitting layer 130 can also be comprised with two or more layers. For example, when the first light-emitting layer and the second light-emitting layer are sequentially stacked from the hole transport layer side to form the light-emitting layer 130, a substance having a hole-transport property is used as the host material of the first light-emitting layer, There is a structure in which a substance having an electron transporting property is used as a host material of the second light emitting layer. In addition, the light-emitting materials included in the first light-emitting layer and the second light-emitting layer may be the same material or different materials, and may be different materials that have a function of emitting light of the same color. A material having a function of emitting light of a color may be used. By using a light emitting material having a function of emitting light of different colors for each of the two light emitting layers, a plurality of light emissions can be obtained simultaneously. In particular, it is preferable to select a light emitting material used for each light emitting layer so that the light emitted by the two light emitting layers is white.

The light emitting layer 130 can be formed by a method such as a vapor deposition method (including a vacuum vapor deposition method), an ink jet method, a coating method, or gravure printing. Further, in addition to the materials described above, an inorganic compound such as a quantum dot or a polymer compound (oligomer, dendrimer, polymer, etc.) may be included.

≪Hole injection layer≫
The hole injection layer 111 has a function of promoting hole injection by reducing a hole injection barrier from one of the pair of electrodes (the electrode 101 or the electrode 102). For example, a transition metal oxide, a phthalocyanine derivative, or an aromatic Formed by a group amine. Examples of the transition metal oxide include molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, and manganese oxide. Examples of the phthalocyanine derivative include phthalocyanine and metal phthalocyanine. Examples of aromatic amines include benzidine derivatives and phenylenediamine derivatives. High molecular compounds such as polythiophene and polyaniline can also be used. For example, self-doped polythiophene poly (ethylenedioxythiophene) / poly (styrenesulfonic acid) is a typical example.

As the hole-injecting layer 111, a layer including a composite material of a hole-transporting material and a material that exhibits an electron-accepting property can be used. Alternatively, a stack of a layer containing a material showing an electron accepting property and a layer containing a hole transporting material may be used. Charges can be transferred between these materials in a steady state or in the presence of an electric field. Examples of the material exhibiting electron acceptability include organic acceptors such as quinodimethane derivatives, chloranil derivatives, and hexaazatriphenylene derivatives. Specifically, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F ₄ -TCNQ), chloranil, 2,3,6,7,10,11 -Hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: And compounds having an electron withdrawing group (in particular, a halogen group such as a fluoro group or a cyano group) such as F6-TCNNQ). In particular, a compound in which an electron withdrawing group is bonded to a condensed aromatic ring having a plurality of heteroatoms such as HAT-CN is preferable because it is thermally stable. [3] Radialene derivatives having an electron-withdrawing group (particularly a halogen group such as a fluoro group or a cyano group) are preferable because of their very high electron-accepting properties. Specifically, α, α ′, α ″ − 1,2,3-cyclopropanetriylidenetris [4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α, α ′, α ″ -1,2,3-cyclopropanetriylidenetris [2,6-dichloro-3,5-difluoro-4- (trifluoromethyl) benzeneacetonitrile], α, α ′, α ″ -1,2,3-cyclopropanetriylidentris [2,3,4, 5,6-pentafluorobenzeneacetonitrile] and the like. In addition, transition metal oxides such as Group 4 to Group 8 metal oxides can be used. Specifically, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, and the like. Among these, molybdenum oxide is preferable because it is stable in the air, has a low hygroscopic property, and is easy to handle.

As the hole transporting material, than the electron can be used transport material having high hole is preferably a material having a 1 × 10 -6 ^{cm 2} / ^Vs or more hole mobility. Specifically, aromatic amines, carbazole derivatives, aromatic hydrocarbons, stilbene derivatives, and the like mentioned as hole transporting materials that can be used for the light-emitting layer 130 can be used, but carbon containing two or more nitrogen atoms can be used. It is particularly preferable to have a heteroaromatic skeleton of several 1 to 20. A nitrogen-containing hetero five-membered ring skeleton is particularly preferable. The hole transporting material may be a polymer compound.

Other examples of the hole transporting material include aromatic hydrocarbons, such as 2-tert-butyl-9,10-di (2-naphthyl) anthracene (abbreviation: t-BuDNA), 2-tert- Butyl-9,10-di (1-naphthyl) anthracene, 9,10-bis (3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 2-tert-butyl-9,10-bis (4-phenylphenyl) ) Anthracene (abbreviation: t-BuDBA), 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), 2-tert-butylanthracene (abbreviation: t-) BuAnth), 9,10-bis (4-methyl-1-naphthyl) anthracene (abbreviation: DMNA), 2-tert-butyl-9, 0-bis [2- (1-naphthyl) phenyl] anthracene, 9,10-bis [2- (1-naphthyl) phenyl] anthracene, 2,3,6,7-tetramethyl-9,10-di (1 -Naphthyl) anthracene, 2,3,6,7-tetramethyl-9,10-di (2-naphthyl) anthracene, 9,9'-bianthryl, 10,10'-diphenyl-9,9'-bianthryl, 10 , 10′-bis (2-phenylphenyl) -9,9′-bianthryl, 10,10′-bis [(2,3,4,5,6-pentaphenyl) phenyl] -9,9′-bianthryl, Anthracene, tetracene, rubrene, perylene, 2,5,8,11-tetra (tert-butyl) perylene and the like can be mentioned. In addition, pentacene, coronene, and the like can also be used. Thus, it is more preferable to use an aromatic hydrocarbon having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or more and having 14 to 42 carbon atoms.

In addition, the aromatic hydrocarbon may have a vinyl skeleton. As the aromatic hydrocarbon having a vinyl group, for example, 4,4′-bis (2,2-diphenylvinyl) biphenyl (abbreviation: DPVBi), 9,10-bis [4- (2,2- Diphenylvinyl) phenyl] anthracene (abbreviation: DPVPA) and the like.

4- {3- [3- (9-phenyl-9H-fluoren-9-yl) phenyl] phenyl} dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4 ′, 4 ″-(benzene-1, 3,5-triyl) tri (dibenzofuran) (abbreviation: DBF3P-II), 1,3,5-tri (dibenzothiophen-4-yl) -benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4 -[4- (9-phenyl-9H-fluoren-9-yl) phenyl] dibenzothiophene (abbreviation: DBTFLP-III), 4- [4- (9-phenyl-9H-fluoren-9-yl) phenyl]- 6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), 4- [3- (triphenylene-2-yl) phenyl] dibenzothiophene (abbreviation: mDB) PTp-II) thiophene compounds, such as, furan compounds, fluorene compounds, triphenylene compounds, can be used phenanthrene compounds. Among the compounds described above, a compound having a pyrrole skeleton, a furan skeleton, a thiophene skeleton, or an aromatic amine skeleton is preferable because it is stable and reliable. In addition, the compound having the skeleton has a high hole transport property and contributes to a reduction in driving voltage.

≪Hole transport layer≫
The hole transport layer 112 is a layer containing a hole transport material, and the hole transport material exemplified as the material of the hole injection layer 111 can be used. Since the hole transport layer 112 has a function of transporting holes injected into the hole injection layer 111 to the light emitting layer 130, the HOMO (High Occupied Molecular Orbital) of the hole injection layer 111 is also known. It is preferable to have a HOMO level that is the same as or close to the position.

In addition, a substance having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher is preferable. However, any substance other than these may be used as long as it has a property of transporting more holes than electrons. Note that the layer containing a substance having a high hole-transport property is not limited to a single layer, and two or more layers containing the above substances may be stacked.

≪Electron transport layer≫
The electron transport layer 118 has a function of transporting electrons injected from the other of the pair of electrodes (the electrode 101 or the electrode 102) through the electron injection layer 119 to the light emitting layer 130. As the electron transporting material, a material having a higher electron transporting property than holes can be used, and a material having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or more is preferable. As a compound that easily receives electrons (a material having an electron transporting property), a π-electron deficient heteroaromatic such as a nitrogen-containing heteroaromatic compound, a metal complex, or the like can be used. Specifically, the pyridine derivatives, bipyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, phenanthroline derivatives, triazole derivatives, benzimidazole derivatives, oxalates, which are listed as electron transporting materials that can be used for the light-emitting layer 130. Examples thereof include diazole derivatives, but it is preferable to have a heteroaromatic skeleton having 1 to 20 carbon atoms containing two or more nitrogen atoms. In particular, a compound having a pyrimidine skeleton and a triazine skeleton is preferable. Further, a substance having an electron mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher is preferable. Note that other than the above substances, any substance that has a property of transporting more electrons than holes may be used for the electron-transport layer. Further, the electron-transporting layer 118 is not limited to a single layer, and two or more layers including the above substances may be stacked.

Moreover, the metal complex which has a heterocyclic ring is mentioned, For example, the metal complex which has a quinoline ligand, a benzoquinoline ligand, an oxazole ligand, or a thiazole ligand is mentioned. Specifically, for example, tris (8-quinolinolato) aluminum (III) (abbreviation: Alq), tris (4-methyl-8-quinolinolato) aluminum (III) (abbreviation: Almq ₃ ), bis (10-hydroxybenzo) [H] quinolinato) beryllium (II) (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4-phenylphenolato) aluminum (III) (abbreviation: BAlq), bis (8-quinolinolato) zinc (II) (abbreviation: Znq) and the like include metal complexes having a quinoline skeleton or a benzoquinoline skeleton. In addition, bis [2- (2-benzoxazolyl) phenolato] zinc (II) (abbreviation: ZnPBO), bis [2- (2-benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ), etc. A metal complex having an oxazole-based or thiazole-based ligand can also be used.

Further, a layer for controlling the movement of electron carriers may be provided between the electron transport layer 118 and the light emitting layer 130. This is a layer obtained by adding a small amount of a substance having a high electron trapping property to a material having a high electron transporting property as described above. By suppressing the movement of electron carriers, the carrier balance can be adjusted. Such a configuration is highly effective in suppressing problems that occur when the electron transporting property of the electron transporting material is significantly higher than the hole transporting property of the hole transporting material (for example, a reduction in device lifetime). .

≪Electron injection layer≫
The electron injection layer 119 has a function of promoting electron injection by reducing an electron injection barrier from the electrode 102. For example, a Group 1 metal, a Group 2 metal, or an oxide, halide, carbonate, or the like thereof is used. Can be used. Alternatively, a composite material of the electron transporting material described above and a material exhibiting an electron donating property can be used. Examples of the material exhibiting electron donating properties include Group 1 metals, Group 2 metals, and oxides thereof. Specifically, alkali metals such as lithium fluoride (LiF), sodium fluoride (NaF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), lithium oxide (LiO _x ), etc., alkaline earth Similar metals, or compounds thereof can be used. Alternatively, a rare earth metal compound such as erbium fluoride (ErF ₃ ) can be used. Further, electride may be used for the electron injection layer 119. Examples of the electride include a substance obtained by adding a high concentration of electrons to a mixed oxide of calcium and aluminum. Alternatively, a substance that can be used for the electron-transport layer 118 may be used for the electron-injection layer 119.

Alternatively, a composite material obtained by mixing an organic compound and an electron donor (donor) may be used for the electron injection layer 119. Such a composite material is excellent in electron injecting property and electron transporting property because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material excellent in transporting the generated electrons. Specifically, for example, a substance (metal complex, heteroaromatic compound, or the like) constituting the electron transport layer 118 described above is used. Can be used. The electron donor may be any substance that exhibits an electron donating property to the organic compound. Specifically, an alkali metal, an alkaline earth metal, or a rare earth metal is preferable, and examples thereof include lithium, sodium, cesium, magnesium, calcium, erbium, and ytterbium. Alkali metal oxides and alkaline earth metal oxides are preferable, and lithium oxide, calcium oxide, barium oxide, and the like can be given. A Lewis base such as magnesium oxide can also be used. Alternatively, an organic compound such as tetrathiafulvalene (abbreviation: TTF) can be used.

Note that the light emitting layer, the hole injection layer, the hole transport layer, the electron transport layer, and the electron injection layer described above are formed by a vapor deposition method (including a vacuum vapor deposition method), an inkjet method, a coating method, a gravure printing, and the like, respectively. Can be formed by a method. In addition to the above materials, the light emitting layer, hole injection layer, hole transport layer, electron transport layer, and electron injection layer described above include inorganic compounds such as quantum dots, and polymer compounds (oligomers, dendrimers). , Polymers, etc.) may be used.

≪Quantum dots≫
A quantum dot is a semiconductor nanocrystal having a size of several nanometers to several tens of nanometers, and is composed of about 1 × 10 ³ to 1 × 10 ⁶ atoms. Since quantum dots shift in energy depending on the size, even if the quantum dots are made of the same material, the emission wavelength differs depending on the size. Therefore, the emission wavelength can be easily changed by changing the size of the quantum dots to be used.

In addition, since the quantum dot has a narrow emission spectrum peak width, it is possible to obtain light emission with good color purity. Furthermore, the theoretical internal quantum efficiency of quantum dots is said to be almost 100%, which is much higher than 25% of organic compounds that exhibit fluorescence and is equivalent to organic compounds that exhibit phosphorescence. For this reason, a light-emitting element with high emission efficiency can be obtained by using quantum dots as a light-emitting material. In addition, quantum dots, which are inorganic materials, are excellent in essential stability, and thus a light-emitting element that is preferable from the viewpoint of life can be obtained.

The materials constituting the quantum dots include group 14 elements, group 15 elements, group 16 elements, compounds composed of a plurality of group 14 elements, elements belonging to groups 4 to 14 and group 16 elements. Compounds of Group 2, elements of Group 16 and Group 16, compounds of Group 13 elements and Group 15 elements, compounds of Group 13 elements and Group 17 elements, Group 14 elements and Group 15 Examples thereof include compounds with elements, compounds of Group 11 elements and Group 17 elements, iron oxides, titanium oxides, chalcogenide spinels, and semiconductor clusters.

Specifically, cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, zinc sulfide, zinc telluride, mercury sulfide, mercury selenide, mercury telluride, indium arsenide, indium phosphide, gallium arsenide , Gallium phosphide, indium nitride, gallium nitride, indium antimonide, gallium phosphide, aluminum arsenide, aluminum arsenide, aluminum antimonide, lead selenide, lead telluride, lead sulfide, indium selenide, indium telluride, sulfide Indium, gallium selenide, arsenic sulfide, arsenic selenide, arsenic telluride, antimony sulfide, antimony selenide, antimony telluride, bismuth sulfide, bismuth selenide, bismuth telluride, silicon, silicon carbide, germanium, tin, selenium, Tellurium, ho Elemental, carbon, phosphorus, boron nitride, boron phosphide, boron arsenide, aluminum nitride, aluminum sulfide, barium sulfide, barium selenide, barium telluride, calcium sulfide, calcium selenide, calcium telluride, beryllium sulfide, beryllium selenide , Beryllium telluride, magnesium sulfide, magnesium selenide, germanium sulfide, germanium selenide, germanium telluride, tin sulfide, tin selenide, tin telluride, lead oxide, copper fluoride, copper chloride, copper bromide, iodide Copper, copper oxide, copper selenide, nickel oxide, cobalt oxide, cobalt sulfide, iron oxide, iron sulfide, manganese oxide, molybdenum sulfide, vanadium oxide, tungsten oxide, tantalum oxide, titanium oxide, zirconium oxide, silicon nitride, germanium nitride ,Aluminum oxide, Barium tanoate, selenium, zinc and cadmium compound, indium, arsenic and phosphorus compound, cadmium, selenium and sulfur compound, cadmium, selenium and tellurium compound, indium, gallium and arsenic compound, indium, gallium and selenium compound Examples thereof include, but are not limited to, compounds of indium, selenium and sulfur, compounds of copper, indium and sulfur, and combinations thereof. Moreover, you may use what is called an alloy type quantum dot whose composition is represented by arbitrary ratios. For example, an alloy type quantum dot of cadmium, selenium, and sulfur is one of effective means for obtaining blue light emission because the emission wavelength can be changed by changing the content ratio of elements.

The structure of the quantum dot includes a core type, a core-shell type, and a core-multishell type, and any of them may be used, but the shell is covered with another inorganic material that covers the core and has a wider band gap. By forming, the influence of defects and dangling bonds existing on the nanocrystal surface can be reduced. Thereby, in order to greatly improve the quantum efficiency of light emission, it is preferable to use a core-shell type or core-multishell type quantum dot. Examples of the shell material include zinc sulfide and zinc oxide.

Quantum dots also have high reactivity because of a high proportion of surface atoms, and aggregation is likely to occur. Therefore, it is preferable that a protective agent is attached or a protective group is provided on the surface of the quantum dots. Aggregation can be prevented and solubility in a solvent can be increased by attaching the protective agent or providing a protective group. It is also possible to reduce the reactivity and improve the electrical stability. Examples of the protecting agent (or protecting group) include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, tripropylphosphine, tributylphosphine, trihexylphosphine, Trialkylphosphines such as octylphosphine, polyoxyethylene alkylphenyl ethers such as polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, tri (n-hexyl) amine, tri (n-octyl) Tertiary amines such as amine and tri (n-decyl) amine, tripropylphosphine oxide, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphite Organic phosphorus compounds such as oxide and tridecylphosphine oxide, polyethylene glycol diesters such as polyethylene glycol dilaurate and polyethylene glycol distearate, and organic nitrogen compounds such as nitrogen-containing aromatic compounds such as pyridine, lutidine, collidine and quinolines , Hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and other amino alkanes, dibutyl sulfide and other dialkyl sulfides, dimethyl sulfoxide and dibutyl sulfoxide and other dialkyl sulfoxides, and thiophene Organic sulfur compounds such as sulfur-containing aromatic compounds, higher fatty acids such as palmitic acid, stearic acid, oleic acid, alcohols, sorbitan fatty acid esters Fatty acid modified polyesters, tertiary amine modified polyurethanes and polyethylene imines, and the like.

Since the band gap increases as the size decreases, the size of the quantum dot is adjusted as appropriate so that light of a desired wavelength can be obtained. As the crystal size decreases, the light emission of the quantum dots shifts to the blue side, that is, to the high energy side, so changing the size of the quantum dots changes the spectral wavelengths in the ultraviolet, visible, and infrared regions. The emission wavelength can be adjusted over a region. As the size (diameter) of the quantum dots, those in the range of 0.5 nm to 20 nm, preferably 1 nm to 10 nm are usually used. In addition, as the quantum dot has a narrower size distribution, the emission spectrum becomes narrower and light emission with good color purity can be obtained. The shape of the quantum dots is not particularly limited, and may be spherical, rod-shaped, disk-shaped, or other shapes. Note that a quantum rod that is a rod-shaped quantum dot has a function of exhibiting light having directivity, and thus a light-emitting element with better external quantum efficiency can be obtained by using the quantum rod as a light-emitting material.

By the way, in many cases, organic EL elements increase luminous efficiency by dispersing a light emitting material in a host material and suppressing concentration quenching of the light emitting material. The host material needs to be a material having a singlet excitation energy level or a triplet excitation energy level higher than that of the light emitting material. In particular, when a blue phosphorescent material is used as a light emitting material, a host material having a triplet excitation energy level higher than that and having an excellent lifetime is required, and its development is extremely difficult. Here, since the quantum dots can maintain the light emission efficiency even if the light emitting layer is constituted only by the quantum dots without using the host material, a light emitting element that is preferable from this point of view can also be obtained. When the light emitting layer is formed only with quantum dots, the quantum dots preferably have a core-shell structure (including a core-multishell structure).

When quantum dots are used for the light emitting material of the light emitting layer, the film thickness of the light emitting layer is 3 nm to 100 nm, preferably 10 nm to 100 nm, and the content of quantum dots in the light emitting layer is 1 to 100% by volume. However, it is preferable to form the light emitting layer only with quantum dots. When forming a light emitting layer in which the quantum dots are dispersed in the host as a light emitting material, the quantum dots are dispersed in the host material, or the host material and the quantum dots are dissolved or dispersed in an appropriate liquid medium. (Spin coating method, casting method, die coating method, blade coating method, roll coating method, ink jet method, printing method, spray coating method, curtain coating method, Langmuir-Blodget method, etc.) may be used. For the light-emitting layer using a phosphorescent light-emitting material, in addition to the wet process, a vacuum vapor deposition method can be suitably used.

Examples of the liquid medium used in the wet process include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, and aromatic carbonization such as toluene, xylene, mesitylene, and cyclohexyl benzene. Hydrogen, aliphatic hydrocarbons such as cyclohexane, decalin, and dodecane, and organic solvents such as dimethyl boramide (DMF) and dimethyl sulfoxide (DMSO) can be used.

≪A pair of electrodes≫
The electrode 101 and the electrode 102 have a function as an anode or a cathode of the light emitting element. The electrode 101 and the electrode 102 can be formed using a metal, an alloy, a conductive compound, a mixture or a stacked body thereof.

One of the electrode 101 and the electrode 102 is preferably formed of a conductive material having a function of reflecting light. Examples of the conductive material include aluminum (Al) or an alloy containing Al. Examples of the alloy containing Al include an alloy containing Al and L (L represents one or more of titanium (Ti), neodymium (Nd), nickel (Ni), and lanthanum (La)). For example, Al and Ti, or an alloy containing Al, Ni, and La. Aluminum has a low resistance value and a high light reflectance. In addition, since aluminum is abundant in the crust and inexpensive, manufacturing cost of a light-emitting element by using aluminum can be reduced. Silver (Ag) or Ag and N (N is yttrium (Y), Nd, magnesium (Mg), ytterbium (Yb), Al, Ti, gallium (Ga), zinc (Zn), indium (In) Represents one or more of tungsten (W), manganese (Mn), tin (Sn), iron (Fe), Ni, copper (Cu), palladium (Pd), iridium (Ir), or gold (Au) ) And the like. Examples of the alloy containing silver include an alloy containing silver, palladium and copper, an alloy containing silver and copper, an alloy containing silver and magnesium, an alloy containing silver and nickel, an alloy containing silver and gold, and silver and ytterbium. Examples thereof include alloys. In addition, transition metals such as tungsten, chromium (Cr), molybdenum (Mo), copper, and titanium can be used.

Light emitted from the light-emitting layer is extracted through one or both of the electrode 101 and the electrode 102. Therefore, at least one of the electrode 101 and the electrode 102 is preferably formed using a conductive material having a function of transmitting light. The conductive material is a conductive material having a visible light transmittance of 40% to 100%, preferably 60% to 100%, and a resistivity of 1 × 10 ⁻² Ω · cm or less. Can be mentioned.

Further, the electrode 101 and the electrode 102 may be formed of a conductive material having a function of transmitting light and a function of reflecting light. Examples of the conductive material include a conductive material having a visible light reflectance of 20% to 80%, preferably 40% to 70%, and a resistivity of 1 × 10 ⁻² Ω · cm or less. Can be mentioned. For example, it can be formed using one or more kinds of conductive metals, alloys, conductive compounds, and the like. Specifically, for example, indium tin oxide (hereinafter referred to as ITO), indium tin oxide containing silicon or silicon oxide (abbreviation: ITSO), indium zinc oxide (indium zinc oxide), or titanium is included. Metal oxides such as indium oxide containing indium oxide-tin oxide, indium-titanium oxide, tungsten oxide, and zinc oxide can be used. Alternatively, a metal thin film with a thickness that allows light to pass therethrough (preferably, a thickness of 1 nm to 30 nm) can be used. As the metal, for example, Ag or an alloy such as Ag and Al, Ag and Mg, Ag and Au, Ag and Yb, or the like can be used.

Note that in this specification and the like, the material having a function of transmitting light may be any material that has a function of transmitting visible light and has conductivity. In addition to a physical conductor, an oxide semiconductor or an organic conductor including an organic substance is included. Examples of the organic conductor containing an organic substance include a composite material obtained by mixing an organic compound and an electron donor (donor), and a composite material obtained by mixing an organic compound and an electron acceptor (acceptor). . In addition, an inorganic carbon-based material such as graphene may be used. The resistivity of the material is preferably 1 × 10 ⁵ Ω · cm or less, and more preferably 1 × 10 ⁴ Ω · cm or less.

Alternatively, one or both of the electrode 101 and the electrode 102 may be formed by stacking a plurality of the above materials.

In order to improve the light extraction efficiency, a material having a higher refractive index than that of the electrode may be formed in contact with the electrode having a function of transmitting light. Such a material may be a material having a function of transmitting visible light, and may be a material having conductivity or not. For example, in addition to the above oxide conductor, an oxide semiconductor and an organic substance can be given. As an organic substance, the material illustrated to the light emitting layer, the positive hole injection layer, the positive hole transport layer, the electron carrying layer, or the electron injection layer is mentioned, for example. In addition, an inorganic carbon-based material or a metal thin film that transmits light can be used, and a plurality of layers of several nm to several tens of nm may be stacked.

In the case where the electrode 101 or the electrode 102 has a function as a cathode, it is preferable to use a material having a low work function (3.8 eV or less). For example, elements belonging to Group 1 or Group 2 of the periodic table (alkali metals such as lithium, sodium and cesium, alkaline earth metals such as calcium and strontium, magnesium and the like), alloys containing these elements (for example, Ag And rare earth metals such as Mg, Al and Li), europium (Eu) and Yb, alloys containing these rare earth metals, alloys containing aluminum and silver, and the like can be used.

Further, when the electrode 101 or the electrode 102 is used as an anode, it is preferable to use a material having a large work function (4.0 eV or more).

The electrode 101 and the electrode 102 may be a stack of a conductive material having a function of reflecting light and a conductive material having a function of transmitting light. In that case, the electrode 101 and the electrode 102 are preferable because they can have a function of adjusting an optical distance so that light having a desired wavelength from each light-emitting layer can resonate and light having a desired wavelength can be strengthened. .

As a method for forming the electrode 101 and the electrode 102, a sputtering method, a vapor deposition method, a printing method, a coating method, an MBE (Molecular Beam Epitaxy) method, a CVD method, a pulse laser deposition method, an ALD (Atomic Layer Deposition) method, or the like is appropriately used. be able to.

<< Board >>
The light-emitting element according to one embodiment of the present invention may be manufactured over a substrate formed of glass, plastic, or the like. As the order of manufacturing on the substrate, the layers may be sequentially stacked from the electrode 101 side or may be sequentially stacked from the electrode 102 side.

Note that as the substrate over which the light-emitting element according to one embodiment of the present invention can be formed, glass, quartz, plastic, or the like can be used, for example. A flexible substrate may be used. The flexible substrate is a substrate that can be bent (flexible), and examples thereof include a plastic substrate made of polycarbonate and polyarylate. Moreover, a film, an inorganic vapor deposition film, etc. can also be used. Note that other materials may be used as long as they function as a support in the manufacturing process of the light-emitting element and the optical element. Or what is necessary is just to have a function which protects a light emitting element and an optical element.

For example, in the present invention and the like, a light emitting element can be formed using various substrates. The kind of board | substrate is not specifically limited. Examples of the substrate include a semiconductor substrate (for example, a single crystal substrate or a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate having stainless steel foil, and a tungsten substrate. , A substrate having a tungsten foil, a flexible substrate, a laminated film, a paper containing a fibrous material, or a base film. Examples of the glass substrate include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. Examples of a flexible substrate, a laminated film, a base film and the like include the following. For example, there are plastics represented by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), and polytetrafluoroethylene (PTFE). Another example is a resin such as acrylic. Alternatively, examples include polypropylene, polyester, polyvinyl fluoride, and polyvinyl chloride. As an example, there are polyamide, polyimide, aramid, epoxy, an inorganic vapor deposition film, papers, and the like.

Alternatively, a flexible substrate may be used as the substrate, and the light emitting element may be formed directly on the flexible substrate. Alternatively, a separation layer may be provided between the substrate and the light-emitting element. The release layer can be used to separate a part from the substrate after the light emitting element is partially or wholly formed thereon, and to transfer the light emitting element to another substrate. At that time, the light-emitting element can be transferred to a substrate having poor heat resistance or a flexible substrate. Note that, for example, a structure of a laminated structure of an inorganic film of a tungsten film and a silicon oxide film or a structure in which a resin film such as polyimide is formed over a substrate can be used for the above-described release layer.

That is, a light emitting element may be formed using a certain substrate, and then the light emitting element may be transferred to another substrate, and the light emitting element may be disposed on another substrate. As an example of a substrate to which the light emitting element is transferred, in addition to the above-described substrate, a cellophane substrate, a stone substrate, a wood substrate, a cloth substrate (natural fiber (silk, cotton, hemp), synthetic fiber (nylon, polyurethane, polyester) or There are recycled fibers (including acetate, cupra, rayon, recycled polyester), leather substrates, rubber substrates, and the like. By using these substrates, a light-emitting element that is not easily broken, a light-emitting element with high heat resistance, a light-emitting element that is reduced in weight, or a light-emitting element that is thinned can be obtained.

Further, for example, a field effect transistor (FET) may be formed on the above-described substrate, and the light-emitting element 150 may be formed on an electrode electrically connected to the FET. Accordingly, an active matrix display device in which driving of the light emitting element 150 is controlled by the FET can be manufactured.

As described above, the structure described in this embodiment can be combined as appropriate with any of the other embodiments.

(Embodiment 2)
In this embodiment, a light-emitting element having a structure different from that of the light-emitting element described in Embodiment 1 and a light-emitting mechanism of the light-emitting element will be described below with reference to FIGS. 3 and 4, portions having the same functions as those shown in FIG. 1A have the same hatch pattern, and the symbols may be omitted. Moreover, the same code | symbol is attached | subjected to the location which has the same function, and the detailed description may be abbreviate | omitted.

<Configuration Example 1 of Light-Emitting Element>
FIG. 3A is a schematic cross-sectional view of the light-emitting element 250. The light-emitting element 250 includes a plurality of light-emitting units (the light-emitting unit 106 and the light-emitting unit 108 in FIG. 3A) between a pair of electrodes (the electrode 101 and the electrode 102). Note that in the light-emitting element 250, the electrode 101 functions as an anode and the electrode 102 functions as a cathode, but the structure of the light-emitting element 250 may be reversed.

In the light-emitting element 250 illustrated in FIG. 3A, the light-emitting unit 106 and the light-emitting unit 108 are stacked, and a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 108. Note that the light emitting unit 106 and the light emitting unit 108 may have the same configuration or different configurations.

The light emitting element 250 includes the light emitting layer 120 and the light emitting layer 170. In addition to the light emitting layer 170, the light emitting unit 106 includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. In addition to the light emitting layer 120, the light emitting unit 108 includes a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

The charge generation layer 115 has a configuration in which an acceptor substance that is an electron acceptor is added to a hole transport material, but a donor substance that is an electron donor is added to the electron transport material. May be. Moreover, both these structures may be laminated | stacked.

In the case where the charge generation layer 115 includes a composite material of an organic compound and an acceptor substance, a composite material that can be used for the hole-injection layer 111 described in Embodiment 1 may be used as the composite material. As the organic compound, various compounds such as an aromatic amine compound, a carbazole compound, an aromatic hydrocarbon, and a high molecular compound (oligomer, dendrimer, polymer, etc.) can be used. Note that as the organic compound, a substance having a hole mobility of 1 × 10 ⁻⁶ cm ² / Vs or higher is preferably used. However, any substance other than these substances may be used as long as it has a property of transporting more holes than electrons. Since a composite material of an organic compound and an acceptor substance is excellent in carrier injecting property and carrier transporting property, low voltage driving and low current driving can be realized. Note that in the case where the surface of the light emitting unit on the anode side is in contact with the charge generation layer 115, the charge generation layer 115 can also serve as a hole injection layer or a hole transport layer of the light emission unit. The unit may not be provided with a hole injection layer or a hole transport layer. Alternatively, when the surface of the light emitting unit on the cathode side is in contact with the charge generation layer 115, the charge generation layer 115 can also serve as an electron injection layer or an electron transport layer of the light emission unit. May have a configuration in which an electron injection layer or an electron transport layer is not provided.

Note that the charge generation layer 115 may be formed as a stacked structure in which a layer including a composite material of an organic compound and an acceptor substance and a layer formed using another material are combined. For example, a layer including a composite material of an organic compound and an acceptor substance may be formed in combination with a layer including one compound selected from electron donating substances and a compound having a high electron transporting property. Alternatively, a layer including a composite material of an organic compound and an acceptor substance may be combined with a layer including a transparent conductive film.

Note that the charge generation layer 115 sandwiched between the light-emitting unit 106 and the light-emitting unit 108 injects electrons into one light-emitting unit and applies holes to the other light-emitting unit when voltage is applied to the electrode 101 and the electrode 102. As long as it injects. For example, in FIG. 3A, when a voltage is applied so that the potential of the electrode 101 is higher than the potential of the electrode 102, the charge generation layer 115 injects electrons into the light-emitting unit 106, and the light-emitting unit 108. Inject holes into

Note that the charge generation layer 115 preferably has a property of transmitting visible light (specifically, the transmittance of visible light to the charge generation layer 115 is 40% or more) from the viewpoint of light extraction efficiency. In addition, the charge generation layer 115 functions even when it has lower conductivity than the pair of electrodes (the electrode 101 and the electrode 102).

By forming the charge generation layer 115 using the above-described material, an increase in driving voltage when the light emitting layer is stacked can be suppressed.

Further, although the light-emitting element having two light-emitting units is described in FIG. 3A, the present invention can be similarly applied to a light-emitting element in which three or more light-emitting units are stacked. As shown in the light-emitting element 250, a plurality of light-emitting units are partitioned between a pair of electrodes by a charge generation layer, thereby enabling high-intensity light emission while maintaining a low current density, and a longer-life light-emitting element Can be realized. In addition, a light-emitting element with low power consumption can be realized.

Note that in each of the above-described configurations, the light emission colors exhibited by the guest materials used for the light-emitting unit 106 and the light-emitting unit 108 may be the same as or different from each other. In the case where the light-emitting unit 106 and the light-emitting unit 108 include guest materials having a function of emitting light of the same color, the light-emitting element 250 is preferably a light-emitting element that exhibits high emission luminance with a small current value. In the case where the light emitting unit 106 and the light emitting unit 108 include a guest material having a function of emitting light of different colors, the light emitting element 250 is preferably a light emitting element that exhibits multicolor light emission. In this case, by using a plurality of light-emitting materials having different emission wavelengths for one or both of the light-emitting layer 120 and the light-emitting layer 170, the light emission spectrum exhibited by the light-emitting element 250 is light in which light emission having different emission peaks is synthesized. Therefore, the emission spectrum has at least two maximum values.

The above configuration is also suitable for obtaining white light emission. White light emission can be obtained by making the lights of the light emitting layer 120 and the light emitting layer 170 have complementary colors. In particular, it is preferable to select the guest material so that white light emission having high color rendering properties or light emission having at least red, green, and blue light is obtained.

In the case of a light-emitting element in which three or more light-emitting units are stacked, the emission colors exhibited by the guest materials used in the respective light-emitting units may be the same or different from each other. In the case of having a plurality of light emitting units that emit light of the same color, the light emission colors exhibited by the plurality of light emitting units can achieve high light emission luminance with a smaller current value than other colors. Such a configuration can be suitably used for adjusting the emission color. In particular, it is suitable when using guest materials that have different luminous efficiencies and exhibit different luminescent colors. For example, in the case of having three layers of light-emitting units, two layers of light-emitting units having the same color fluorescent material and one layer of a light-emitting unit having a phosphorescent material exhibiting an emission color different from the fluorescent material The emission intensity of phosphorescence can be adjusted. That is, the intensity of the emission color can be adjusted by the number of the light emitting units.

In the case of a light emitting device having two layers of such fluorescent light emitting units and one layer of phosphorescent light emitting units, a light emitting device containing two layers of light emitting units containing a blue fluorescent material and one layer of light emitting units containing a yellow phosphorescent material, or blue A light emitting element having two light emitting units containing a fluorescent material and one light emitting layer unit containing a red phosphorescent material and a green phosphorescent material, two light emitting units containing a blue fluorescent material and a red phosphorescent material, a yellow phosphorescent material, and a green phosphorescent material A light-emitting element having one light-emitting layer unit containing a material is preferable because white light emission can be efficiently obtained.

Further, at least one of the light emitting layer 120 or the light emitting layer 170 may be further divided into layers, and a different light emitting material may be included in each of the divided layers. That is, at least one of the light-emitting layer 120 or the light-emitting layer 170 may be formed of two or more layers. For example, when a light emitting layer is formed by sequentially stacking a first light emitting layer and a second light emitting layer from the hole transport layer side, a material having a hole transport property is used as a host material of the first light emitting layer. There is a configuration in which a material having an electron transporting property is used as the host material of the light emitting layer 2. In this case, the light emitting materials included in the first light emitting layer and the second light emitting layer may be the same material or different materials, and may be materials having a function of emitting light of the same color. A material having a function of emitting light of different colors may be used. With a structure including a plurality of light emitting materials having a function of emitting light of different colors, white light emission having high color rendering properties composed of three primary colors or four or more light emission colors can be obtained.

Note that by applying the structure described in Embodiment 1 to at least one of a plurality of units, a light-emitting element with high light emission efficiency, low driving voltage, and high reliability can be provided. Can do.

Further, the light-emitting layer 120 included in the light-emitting unit 108 includes a guest material 121 and a host material 122 as illustrated in FIG. The guest material 121 will be described below as a fluorescent material.

<< Light-Emitting Mechanism of Light-Emitting Layer 120 >>
The light emission mechanism of the light emitting layer 120 will be described below.

Excitons are generated by recombination of electrons and holes injected from the pair of electrodes (electrode 101 and electrode 102) or the charge generation layer in the light emitting layer 120. Since the host material 122 is present in a large amount compared to the guest material 121, the excited state of the host material 122 is almost formed by the generation of excitons. An exciton is a carrier (electron and hole) pair.

When the excited state of the formed host material 122 is a singlet excited state, the singlet excitation energy is transferred from the S1 level of the host material 122 to the S1 level of the guest material 121, and the singlet excitation of the guest material 121 is performed. A state is formed.

Since the guest material 121 is a fluorescent material, the guest material 121 emits light quickly when a singlet excited state is formed in the guest material 121. At this time, in order to obtain high luminous efficiency, the guest material 121 preferably has a high fluorescence quantum yield. Note that the same applies to the guest material 121 in which carriers are recombined and the generated excited state is a singlet excited state.

Next, a case where a triplet excited state of the host material 122 is formed by carrier recombination will be described. FIG. 3C shows the correlation between energy levels of the host material 122 and the guest material 121 in this case. In addition, the notations and symbols in FIG. 3C are as follows. Note that since the T1 level of the host material 122 is preferably lower than the T1 level of the guest material 121, FIG. 3C illustrates this case, but the T1 level of the host material 122 is higher than that of the guest material 121. It may be higher than the T1 level.

Guest (121): Guest material 121 (fluorescent material)
Host (122): Host material 122
S _FG : S1 level of guest material 121 (fluorescent material) T _FG : T1 level of guest material 121 (fluorescent material) S _FH : S1 level of host material 122 T _FH : T1 of host material 122 Level

As shown in FIG. 3 (C), triplet-triplet annihilation (TTA) causes triplet excitons generated by carrier recombination to interact with each other, exchange excitation energy with each other, and by the exchange of spin angular momentum, resulting in S1 level position of the host material 122 reactions to be converted to singlet excitons having an energy of (S _FH) is caused (see FIG. 3 (C) TTA). The singlet excitation energy of the host material 122 causes energy transfer from S _FH to the S1 level (S _FG ) of the guest material 121 having lower energy (see FIG. 3C, route E ₁ ). A singlet excited state of 121 is formed, and the guest material 121 emits light.

When the density of triplet excitons in the light emitting layer 120 is sufficiently high (for example, 1 × 10 ¹² m ⁻³ or more), deactivation of the singlet excitons alone is ignored, and two adjacent triplet excitations are performed. Only the reaction by the child can be considered.

Further, when a carrier is recombined in the guest material 121 to form a triplet excited state, the triplet excited state of the guest material 121 is thermally deactivated, so that it is difficult to use for light emission. However, if the T1 level position of the host material 122 _{(T FH)} is T1 level position of the guest material 121 _{(T FG)} lower than the triplet excitation energy of the guest material 121, T1 level position of the guest material 121 _{(T FG)} To the T1 level (T _FH ) of the host material 122 (see FIG. 3C, route E ₂ ), and then used for TTA.

That is, the host material 122 preferably has a function of converting triplet excitation energy to singlet excitation energy by TTA. By doing so, part of the triplet excitation energy generated in the light-emitting layer 120 is converted into singlet excitation energy by TTA in the host material 122, and the singlet excitation energy is transferred to the guest material 121, whereby fluorescence It becomes possible to take out as light emission (Emission). For this purpose, the S1 level (S _FH ) of the host material 122 is preferably higher than the S1 level (S _FG ) of the guest material 121. The T1 level (T _FH ) of the host material 122 is preferably lower than the T1 level (T _FG ) of the guest material 121.

Note that in particular, when the T1 level (T _FG ) of the guest material 121 is lower than the T1 level (T _FH ) of the host material 122, the weight ratio of the host material 122 to the guest material 121 is as follows. A lower weight ratio is preferred. Specifically, the weight ratio of the guest material 121 when the host material 122 is 1 is preferably greater than 0 and 0.05 or less. By doing so, the probability that carriers are recombined in the guest material 121 can be reduced. In addition, the probability of energy transfer from the T1 level (T _FH ) of the host material 122 to the T1 level (T _FG ) of the guest material 121 can be reduced.

The host material 122 may be composed of a single compound or a plurality of compounds.

In the case where the light emitting unit 106 and the light emitting unit 108 have guest materials having different emission colors, the light emission from the light emitting layer 120 has a light emission peak on the shorter wavelength side than the light emission from the light emitting layer 170. Is preferred. A light-emitting element using a material having a high triplet excitation energy level tends to deteriorate in luminance. Thus, by using TTA for the light-emitting layer that emits light with a short wavelength, a light-emitting element with low luminance deterioration can be provided.

<Configuration Example 2 of Light-Emitting Element>
FIG. 4A is a schematic cross-sectional view of the light-emitting element 252.

A light-emitting element 252 illustrated in FIG. 4A has a plurality of light-emitting units (in FIG. 4A) between a pair of electrodes (the electrode 101 and the electrode 102), similarly to the light-emitting element 250 described above. A light emitting unit 106 and a light emitting unit 110). At least one light emitting unit has a configuration similar to that of the EL layer 100. Note that the light emitting unit 106 and the light emitting unit 110 may have the same configuration or different configurations.

In the light-emitting element 252 illustrated in FIG. 4A, the light-emitting unit 106 and the light-emitting unit 110 are stacked, and a charge generation layer 115 is provided between the light-emitting unit 106 and the light-emitting unit 110. For example, the EL layer 100 is preferably used for the light-emitting unit 106.

The light emitting element 252 includes a light emitting layer 140 and a light emitting layer 170. In addition to the light emitting layer 170, the light emitting unit 106 includes a hole injection layer 111, a hole transport layer 112, an electron transport layer 113, and an electron injection layer 114. In addition to the light emitting layer 140, the light emitting unit 110 includes a hole injection layer 116, a hole transport layer 117, an electron transport layer 118, and an electron injection layer 119.

The light emitting layer 140 included in the light emitting unit 110 includes a guest material 141 and a host material 142 as shown in FIG. The host material 142 includes an organic compound 142_1 and an organic compound 142_2. Note that the guest material 141 included in the light-emitting layer 140 is described below as a phosphorescent material.

<< Light-Emitting Mechanism of Light-Emitting Layer 140 >>
Next, the light emission mechanism of the light emitting layer 140 will be described below.

The organic compound 142_1 and the organic compound 142_2 included in the light-emitting layer 140 form an exciplex.

The combination of the organic compound 142_1 and the organic compound 142_2 may be any combination that can form an exciplex with each other, but one is a compound having a hole transporting property and the other is a compound having an electron transporting property. More preferably.

FIG. 4C illustrates the correlation of energy levels among the organic compound 142_1, the organic compound 142_2, and the guest material 141 in the light-emitting layer 140. In addition, the notation and code | symbol in FIG.4 (C) are as follows.
Guest (141): Guest material 141 (phosphorescent material)
Host (142_1): Organic compound 142_1 (host material)
Host (142_2): Organic compound 142_2 (host material)
· _{T PG:} guest material 141 T1 level _{· S} of (phosphorescent material) _PH1: organic compound 142_1 (host material) of the S1 level _{· T PH1:} organic compound 142_1 (host material) of the T1 level _{· S PH2:} Organic S1 level of compound 142_2 (host material) • T _PH2 : T1 level of organic compound 142_2 (host material) • S _PE : S1 level of exciplex • T _PE : T1 level of exciplex

The organic compound 142_1 and the organic compound 142_2 form an exciplex, and the S1 level (S _PE ) and the T1 level (T _PE ) of the exciplex are adjacent to each other (FIG. 4C, route E ₃ reference).

One of the organic compound 142_1 and the organic compound 142_2 receives a hole and the other receives an electron, so that an exciplex is quickly formed. Alternatively, when one is in an excited state, it rapidly interacts with the other to form an exciplex. Therefore, most excitons in the light-emitting layer 140 exist as exciplexes. The excitation energy level (S _PE or T _PE ) of the exciplex is lower because it is lower than the S1 level (S _PH1 and S _PH2 ) of the host material (organic compound 142_1 and organic compound 142_2) that forms the exciplex. The excited state of the host material 142 can be formed with the excitation energy. As a result, the driving voltage of the light emitting element can be lowered.

Then, the energy of both the (S _PE ) and (T _PE ) of the exciplex is transferred to the T1 level of the guest material 141 (phosphorescent material), and emission (Emission) is obtained (FIG. 4C, route E). _4, _E reference _5).

Note that the T1 level (T _PE ) of the exciplex is preferably larger than the T1 level (T _PG ) of the guest material 141. By doing so, the singlet excitation energy and triplet excitation energy of the generated exciplex are changed from the S1 level (S _PE ) and T1 level (T _PE ) of the exciplex to the T1 level (T _PG ) of the guest material 141. ) To transfer energy.

In addition, in order to efficiently transfer excitation energy from the exciplex to the guest material 141, the T1 level (T _PE ) of the exciplex corresponds to each organic compound (organic compound 142_1 and organic compound 142_2) that forms the exciplex. It is preferable that it is equal to or smaller than the T1 level ( _TPH1 and _TPH2 ). Accordingly, quenching of the triplet excitation energy of the exciplex by each organic compound (organic compound 142_1 and organic compound 142_2) is difficult to occur, and energy transfer from the exciplex to the guest material 141 is efficiently generated.

In addition, in order for the organic compound 142_1 and the organic compound 142_2 to efficiently form an exciplex, one of the organic compounds 142_1 and 142_2 has a higher HOMO level than the other HOMO level, and one LUMO level. Is preferably higher than the other LUMO level. For example, when the organic compound 142_1 has a hole-transport property and the organic compound 142_2 has an electron-transport property, the HOMO level of the organic compound 142_1 is preferably higher than the HOMO level of the organic compound 142_2. The LUMO level is preferably higher than the LUMO level of the organic compound 142_2. Alternatively, when the organic compound 142_2 has a hole-transport property and the organic compound 142_1 has an electron-transport property, the HOMO level of the organic compound 142_2 is preferably higher than the HOMO level of the organic compound 142_1. The LUMO level is preferably higher than the LUMO level of the organic compound 142_1. Specifically, the energy difference between the HOMO level of the organic compound 142_1 and the HOMO level of the organic compound 142_2 is preferably 0.05 eV or more, more preferably 0.1 eV or more, and still more preferably 0.8. 2 eV or more. The energy difference between the LUMO level of the organic compound 142_1 and the LUMO level of the organic compound 142_2 is preferably 0.05 eV or more, more preferably 0.1 eV or more, and further preferably 0.2 eV or more. is there.

Further, when the combination of the organic compound 142_1 and the organic compound 142_2 is a combination of a compound having a hole transporting property and a compound having an electron transporting property, the carrier balance can be easily controlled by the mixture ratio. Become. Specifically, a compound having a hole transporting property: a compound having an electron transporting property = 1: 9 to 9: 1 (weight ratio) is preferable. In addition, since the carrier balance can be easily controlled by having this configuration, the carrier recombination region can be easily controlled.

When the light emitting layer 140 has the above-described structure, light emission from the guest material 141 (phosphorescent material) of the light emitting layer 140 can be efficiently obtained.

Note that the processes of the routes E _{3 to} E ₅ described above may be referred to as ExTET (Exciplex-Triple Energy Transfer) in this specification and the like. In other words, the light-emitting layer 140 has a supply of excitation energy from the exciplex to the guest material 141. Note that this is not necessarily the reverse intersystem crossing efficiency from T _PE to S _PE is high when, because there is no great need emission quantum yield from S _PE, it is possible to widely select a material.

Further, it is preferable that the light emission from the light emitting layer 170 has a light emission peak on the shorter wavelength side than the light emission from the light emitting layer 140. A light-emitting element using a phosphorescent material that emits light having a short wavelength tends to deteriorate in luminance. Therefore, a light-emitting element with small luminance deterioration can be provided by using short-wavelength light emission as fluorescent light emission.

<Examples of materials that can be used for the light emitting layer>
Next, materials that can be used for the light-emitting layer 120, the light-emitting layer 140, and the light-emitting layer 170 are described below.

<< Materials that can be used for the light-emitting layer 120 >>
In the light emitting layer 120, the host material 122 is present in the largest amount by weight, and the guest material 121 (fluorescent material) is dispersed in the host material 122. The S1 level of the host material 122 is higher than the S1 level of the guest material 121 (fluorescent material), and the T1 level of the host material 122 is preferably lower than the T1 level of the guest material 121 (fluorescent material). .

In the light emitting layer 120, the guest material 121 is not particularly limited, but anthracene derivatives, tetracene derivatives, chrysene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, stilbene derivatives, acridone derivatives, coumarin derivatives, phenoxazine derivatives, phenothiazine derivatives. The fluorescent compound shown in Embodiment Mode 1 can be preferably used.

There is no particular limitation on a material that can be used for the host material 122 in the light-emitting layer 120; for example, tris (8-quinolinolato) aluminum (III) (abbreviation: Alq), tris (4-methyl-) 8-quinolinolato) aluminum (III) (abbreviation: Almq ₃ ), bis (10-hydroxybenzo [h] quinolinato) beryllium (II) (abbreviation: BeBq ₂ ), bis (2-methyl-8-quinolinolato) (4- Phenylphenolato) aluminum (III) (abbreviation: BAlq), bis (8-quinolinolato) zinc (II) (abbreviation: Znq), bis [2- (2-benzoxazolyl) phenolato] zinc (II) (abbreviation) : ZnPBO), gold such as bis [2- (2-benzothiazolyl) phenolato] zinc (II) (abbreviation: ZnBTZ) Genus complex, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis [5- (p-tert- Butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (abbreviation: OXD-7), 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl)- 1,2,4-triazole (abbreviation: TAZ), 2,2 ′, 2 ″-(1,3,5-benzenetriyl) tris (1-phenyl-1H-benzimidazole) (abbreviation: TPBI), Bathophenanthroline (abbreviation: BPhen), bathocuproin (abbreviation: BCP), 9- [4- (5-phenyl-1,3,4-oxadiazol-2-yl) phenyl] -9H-carbazole (abbreviation: CO11) Na Heterocyclic compounds, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: NPB or α-NPD), N, N′-bis (3-methylphenyl) -N , N′-diphenyl- [1,1′-biphenyl] -4,4′-diamine (abbreviation: TPD), 4,4′-bis [N- (spiro-9,9′-bifluoren-2-yl) And aromatic amine compounds such as —N-phenylamino] biphenyl (abbreviation: BSPB). In addition, condensed polycyclic aromatic compounds such as anthracene derivatives, phenanthrene derivatives, pyrene derivatives, chrysene derivatives, and dibenzo [g, p] chrysene derivatives can be given. Specifically, 9,10-diphenylanthracene (abbreviation: DPAnth) N, N-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazol-3-amine (abbreviation: CzA1PA), 4- (10-phenyl-9-anthryl) triphenyl Amine (abbreviation: DPhPA), 4- (9H-carbazol-9-yl) -4 ′-(10-phenyl-9-anthryl) triphenylamine (abbreviation: YGAPA), N, 9-diphenyl-N- [4 -(10-phenyl-9-anthryl) phenyl] -9H-carbazol-3-amine (abbreviation: PCAPA), N, 9-diphenyl-N- {4- [4- (10-phenyl-9-anthryl) phenyl] phenyl} -9H-carbazol-3-amine (abbreviation: PCAPBA), N, 9-diphenyl-N- ( 9,10-diphenyl-2-anthryl) -9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N, N, N ′, N ′, N ″ , N ″, N ′ ″, N ′ ″-octaphenyldibenzo [g, p] chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9- [4- (10-phenyl- 9-anthryl) phenyl] -9H-carbazole (abbreviation: CzPA), 3,6-diphenyl-9- [4- (10-phenyl-9-anthryl) phenyl] -9H-carbazole (abbreviation: DPCzPA), 9 10-bis (3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 9,10-di (2-naphthyl) anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di (2-naphthyl) ) Anthracene (abbreviation: t-BuDNA), 9,9′-bianthryl (abbreviation: BANT), 9,9 ′-(stilbene-3,3′-diyl) diphenanthrene (abbreviation: DPNS), 9,9′- (Stilbene-4,4′-diyl) diphenanthrene (abbreviation: DPNS2), 3,3 ′, 3 ″-(benzene-1,3,5-triyl) tripylene (abbreviation: TPB3), and the like can be given. . In addition, a substance having an energy gap larger than the energy gap of the guest material 121 may be selected from one or more kinds from among these and known substances.

In addition, the light emitting layer 120 can also be comprised by two or more layers. For example, in the case where the first light-emitting layer and the second light-emitting layer are sequentially stacked from the hole transport layer side to form the light-emitting layer 120, a substance having a hole-transport property is used as the host material of the first light-emitting layer, There is a structure in which a substance having an electron transporting property is used as a host material of the second light emitting layer.

Further, in the light emitting layer 120, the host material 122 may be composed of one kind of compound or a plurality of compounds. Alternatively, the light-emitting layer 120 may include a material other than the host material 122 and the guest material 121.

<< Materials that can be used for the light-emitting layer 140 >>
In the light emitting layer 140, the host material 142 is present in the largest amount by weight, and the guest material 141 (phosphorescent material) is dispersed in the host material 142. The T1 level of the host material 142 (the organic compound 142_1 and the organic compound 142_2) of the light-emitting layer 140 is preferably higher than the T1 level of the guest material 141.

Examples of the organic compound 142_1 include zinc and aluminum-based metal complexes, oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, Bipyridine derivatives, phenanthroline derivatives and the like can be mentioned. Other examples include aromatic amines and carbazole derivatives. Specifically, the electron transporting material and the hole transporting material described in Embodiment 1 can be used. In addition, the organic compound represented by the general formula (G0) is more preferable.

As the organic compound 142_2, a combination capable of forming an exciplex with the organic compound 142_1 is preferable. Specifically, the electron transporting material and the hole transporting material described in Embodiment 1 can be used. In this case, the emission peak of the exciplex formed by the organic compound 142_1 and the organic compound 142_2 is an absorption band of the triplet MLCT (Metal to Ligand Charge Transfer) transition of the guest material 141 (phosphorescent material), more specifically, The organic compound 142_1, the organic compound 142_2, and the guest material 141 (phosphorescent material) are preferably selected so as to overlap with the absorption band on the longest wavelength side. As a result, a light emitting device with dramatically improved luminous efficiency can be obtained. However, when a thermally activated delayed fluorescent material is used instead of a phosphorescent material, the absorption band on the longest wavelength side is a singlet absorption. A belt is preferred.

Examples of the guest material 141 (phosphorescent material) include iridium, rhodium, or platinum-based organometallic complexes, or metal complexes. Among these, organic iridium complexes such as iridium-based orthometal complexes are preferable. Examples of orthometalated ligands include 4H-triazole ligands, 1H-triazole ligands, imidazole ligands, pyridine ligands, pyrimidine ligands, pyrazine ligands, and isoquinoline ligands. Can be mentioned. Examples of the metal complex include a platinum complex having a porphyrin ligand. Specifically, the materials exemplified as the guest material 132 described in Embodiment 1 can be used.

The light emitting material included in the light emitting layer 140 may be any material that can convert triplet excitation energy into light emission. Examples of the material capable of converting the triplet excitation energy into light emission include a thermally activated delayed fluorescent material in addition to the phosphorescent material. Therefore, the portion described as phosphorescent material may be read as thermally activated delayed fluorescent material.

In addition, the material that exhibits thermally activated delayed fluorescence may be a material that can generate a singlet excited state from a triplet excited state by reverse intersystem crossing alone, or a plurality of materials that form an exciplex (Exciplex). It may be composed of

When the thermally activated delayed fluorescent material is composed of one type of material, specifically, the thermally activated delayed fluorescent material shown in the first embodiment can be used.

In addition, when a thermally activated delayed fluorescent material is used as a host material, it is preferable to use a combination of two types of compounds that form an exciplex. In this case, it is particularly preferable to use a compound that easily receives electrons, which is a combination that forms the exciplex shown above, and a compound that easily receives holes.

<< Materials that can be used for light-emitting layer 170 >>
As a material that can be used for the light-emitting layer 170, a material that can be used for the light-emitting layer described in Embodiment 1 may be used, so that a light-emitting element with high emission efficiency can be manufactured.

Further, the light emission color of the light emitting material contained in the light emitting layer 120, the light emitting layer 140, and the light emitting layer 170 is not limited, and may be the same or different. Since the light emission obtained from each is mixed and taken out of the device, the light emitting device can give white light when, for example, the light emission colors of both are complementary colors. In consideration of the reliability of the light emitting element, the emission peak wavelength of the light emitting material included in the light emitting layer 120 is preferably shorter than that of the light emitting material included in the light emitting layer 170.

Note that the light-emitting unit 106, the light-emitting unit 108, the light-emitting unit 110, and the charge generation layer 115 can be formed by a method such as an evaporation method (including a vacuum evaporation method), an inkjet method, a coating method, or gravure printing.

As described above, the structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

(Embodiment 3)
5A is a top view illustrating the light-emitting device, and FIG. 5B is a cross-sectional view taken along lines AB and CD of FIG. 5A. This light-emitting device includes a drive circuit portion (source side drive circuit) 601, a pixel portion 602, and a drive circuit portion (gate side drive circuit) 603 indicated by dotted lines, for controlling light emission of the light emitting element. Reference numeral 604 denotes a sealing substrate, reference numeral 625 denotes a desiccant, reference numeral 605 denotes a sealing material, and the inside surrounded by the sealing material 605 is a space 607.

Note that the routing wiring 608 is a wiring for transmitting a signal input to the source side driving circuit 601 and the gate side driving circuit 603, and a video signal, a clock signal, an FPC (flexible printed circuit) 609 serving as an external input terminal, Receives start signal, reset signal, etc. Although only the FPC is shown here, a printed wiring board (PWB: Printed Wiring Board) may be attached to the FPC. The light-emitting device in this specification includes not only a light-emitting device body but also a state in which an FPC or a PWB is attached thereto.

Next, a cross-sectional structure of the light-emitting device is described with reference to FIG. A driver circuit portion and a pixel portion are formed over the element substrate 610. Here, a source side driver circuit 601 that is a driver circuit portion and one pixel in the pixel portion 602 are shown.

Note that the source side driver circuit 601 is a CMOS circuit in which an n-channel TFT 623 and a p-channel TFT 624 are combined. The driving circuit may be formed of various CMOS circuits, PMOS circuits, and NMOS circuits. In this embodiment mode, a driver integrated type in which a driver circuit is formed over a substrate is shown; however, this is not necessarily required, and the driver circuit can be formed outside the substrate.

The pixel portion 602 is formed of a pixel including a switching TFT 611, a current control TFT 612, and a first electrode 613 electrically connected to the drain thereof. Note that an insulator 614 is formed so as to cover an end portion of the first electrode 613. The insulator 614 can be formed using a positive photosensitive resin film.

In order to improve the coverage of the film formed over the insulator 614, a surface having a curvature is formed at the upper end portion or the lower end portion of the insulator 614. For example, when photosensitive acrylic is used as a material for the insulator 614, it is preferable that only the upper end portion of the insulator 614 has a curved surface. The curvature radius of the curved surface is preferably 0.2 μm or more and 0.3 μm or less. Further, as the insulator 614, any of photosensitive materials such as a negative type and a positive type can be used.

An EL layer 616 and a second electrode 617 are formed over the first electrode 613. Here, as a material used for the first electrode 613 functioning as an anode, a material having a high work function is preferably used. For example, an ITO film or an indium tin oxide film containing silicon, a single layer such as an indium oxide film containing 2 wt% or more and 20 wt% or less of zinc oxide, a titanium nitride film, a chromium film, a tungsten film, a Zn film, or a Pt film In addition to the film, a stack of titanium nitride and a film containing aluminum as a main component, a three-layer structure of a titanium nitride film, a film containing aluminum as a main component, and a titanium nitride film can be used. Note that with a stacked structure, resistance as a wiring is low, good ohmic contact can be obtained, and a function as an anode can be obtained.

The EL layer 616 is formed by various methods such as an evaporation method using an evaporation mask, an inkjet method, and a spin coating method. The material forming the EL layer 616 may be a low molecular compound or a high molecular compound (including an oligomer and a dendrimer).

Further, as a material used for the second electrode 617 formed over the EL layer 616 and functioning as a cathode, a material having a low work function (Al, Mg, Li, Ca, or an alloy or compound thereof, MgAg, MgIn, AlLi or the like is preferably used. Note that in the case where light generated in the EL layer 616 passes through the second electrode 617, the second electrode 617 includes a thin metal film and a transparent conductive film (ITO, 2 wt% or more and 20 wt% or less). A stack of indium oxide containing zinc oxide, indium tin oxide containing silicon, zinc oxide (ZnO), or the like is preferably used.

Note that the light-emitting element 618 is formed by the first electrode 613, the EL layer 616, and the second electrode 617. The light-emitting element 618 is preferably a light-emitting element having the structure of

Embodiments

1 and 2. Note that a plurality of light-emitting elements are formed in the pixel portion; however, in the light-emitting device in this embodiment, the light-emitting element having the structure described in

Embodiments

3 and 4 and other structures are used. Both of the light emitting elements having the above may be included.

Further, the sealing substrate 604 is attached to the element substrate 610 with the sealant 605, whereby the light-emitting element 618 is provided in the space 607 surrounded by the element substrate 610, the sealing substrate 604, and the sealant 605. Yes. Note that the space 607 is filled with a filler and may be filled with an inert gas (nitrogen, argon, or the like), or may be filled with a resin or a desiccant, or both.

Note that an epoxy resin or glass frit is preferably used for the sealant 605. Moreover, it is desirable that these materials are materials that do not transmit moisture and oxygen as much as possible. In addition to a glass substrate and a quartz substrate, a plastic substrate made of FRP (Fiber Reinforced Plastics), PVF (polyvinyl fluoride), polyester, acrylic, or the like can be used as a material used for the sealing substrate 604.

As described above, a light-emitting device using the light-emitting element described in

Embodiments

3 and 4 can be obtained.

<Configuration Example 1 of Light-Emitting Device>
FIG. 6 illustrates an example of a light emitting device in which a light emitting element that emits white light is formed and a colored layer (color filter) is formed as an example of the light emitting device.

6A shows a substrate 1001, a base insulating film 1002, a gate insulating film 1003,

gate electrodes

1006, 1007, and 1008, a first interlayer insulating film 1020, a second interlayer insulating film 1021, a peripheral portion 1042, and a pixel portion. 1040, a driving circuit portion 1041, a

first electrode

1024W, 1024R, 1024G, and 1024B of a light emitting element, a partition wall 1026, an EL layer 1028, a second electrode 1029 of the light emitting element, a sealing substrate 1031, a sealing material 1032, and the like are illustrated. ing.

In FIGS. 6A and 6B, colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B) are provided over a transparent base material 1033. Further, a black layer (black matrix) 1035 may be further provided. The transparent base material 1033 provided with the coloring layer and the black layer is aligned and fixed to the substrate 1001. Note that the colored layer and the black layer are covered with an overcoat layer 1036. In FIG. 6A, there are a light emitting layer in which light is emitted outside without passing through the colored layer, and a light emitting layer in which light is emitted through the colored layer of each color and is transmitted through the colored layer. Since the light that does not pass is white, and the light that passes through the colored layer is red, blue, and green, an image can be expressed by pixels of four colors.

FIG. 6B illustrates an example in which the red colored layer 1034R, the green colored layer 1034G, and the blue colored layer 1034B are formed between the gate insulating film 1003 and the first interlayer insulating film 1020. As shown in FIG. 6B, the coloring layer may be provided between the substrate 1001 and the sealing substrate 1031.

In the light-emitting device described above, a light-emitting device having a structure in which light is extracted to the substrate 1001 side where the TFT is formed (bottom emission type) is used. However, a structure in which light is extracted from the sealing substrate 1031 side (top-emission type). ).

<Configuration Example 2 of Light Emitting Device>
A cross-sectional view of a top emission type light emitting device is shown in FIG. In this case, a substrate that does not transmit light can be used as the substrate 1001. Until the connection electrode for connecting the TFT and the anode of the light emitting element is manufactured, it is formed in the same manner as the bottom emission type light emitting device. Thereafter, a third interlayer insulating film 1037 is formed so as to cover the electrode 1022. This insulating film may play a role of planarization. The third interlayer insulating film 1037 can be formed using various other materials in addition to the same material as the second interlayer insulating film 1021.

The first

lower electrodes

1025W, 1025R, 1025G, and 1025B of the light emitting elements are anodes here, but may be cathodes. In the case of a top emission type light emitting device as shown in FIG. 7, the

lower electrodes

1025W, 1025R, 1025G, and 1025B are preferably reflective electrodes. Note that the second electrode 1029 preferably has a function of reflecting light and a function of transmitting light. In addition, it is preferable that a microcavity structure be applied between the second electrode 1029 and the

lower electrodes

1025W, 1025R, 1025G, and 1025B to have a function of amplifying light of a specific wavelength. The EL layer 1028 has a structure as described in Embodiment 2 and has an element structure in which white light emission can be obtained.

In FIGS. 6A, 6B, and 7, the structure of the EL layer that can emit white light may be realized by using a plurality of light-emitting layers, a plurality of light-emitting units, or the like. . The configuration for obtaining white light emission is not limited to these.

In the top emission structure as shown in FIG. 7, sealing can be performed with a sealing substrate 1031 provided with colored layers (a red colored layer 1034R, a green colored layer 1034G, and a blue colored layer 1034B). A black layer (black matrix) 1030 may be provided on the sealing substrate 1031 so as to be positioned between the pixels. The colored layer (red colored layer 1034R, green colored layer 1034G, blue colored layer 1034B) or black layer (black matrix) may be covered with an overcoat layer. Note that the sealing substrate 1031 is a light-transmitting substrate.

Although an example in which full color display is performed with four colors of red, green, blue, and white is shown here, the present invention is not particularly limited, and full color display may be performed with three colors of red, green, and blue. Further, full color display may be performed with four colors of red, green, blue, and yellow.

Embodiments

1 and 2 can be obtained.

Note that this embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 4)
In this embodiment, an electronic device of one embodiment of the present invention will be described.

Since one embodiment of the present invention is a light-emitting element using an organic EL, a highly reliable electronic device having a flat surface and favorable light emission efficiency can be manufactured. According to one embodiment of the present invention, a highly reliable electronic device having a curved surface and favorable emission efficiency can be manufactured. Further, according to one embodiment of the present invention, a highly reliable electronic device having flexibility and favorable light emission efficiency can be manufactured.

Electronic devices include, for example, television devices, desktop or notebook personal computers, monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones, portable game consoles, personal digital assistants, audio devices Large game machines such as playback devices and pachinko machines are listed.

In addition, the light-emitting device of one embodiment of the present invention can achieve high visibility regardless of the intensity of external light. Therefore, it can be suitably used for a portable electronic device, a wearable electronic device (wearable device), an electronic book terminal, and the like.

A portable information terminal 900 illustrated in FIGS. 8A and 8B includes a housing 901, a housing 902, a display portion 903, a hinge portion 905, and the like.

The housing 901 and the housing 902 are connected by a hinge portion 905. The portable information terminal 900 can be expanded from the folded state (FIG. 8A) as shown in FIG. 8B. Thereby, when carrying, it is excellent in portability, and when using, it is excellent in visibility by a large display area.

The portable information terminal 900 is provided with a flexible display portion 903 across a housing 901 and a housing 902 connected by a hinge portion 905.

A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 903. Thereby, a portable information terminal can be manufactured with a high yield.

The display unit 903 can display at least one of document information, a still image, a moving image, and the like. When displaying document information on the display unit, the portable information terminal 900 can be used as an electronic book terminal.

When the portable information terminal 900 is deployed, the display unit 903 is held in a greatly curved form. For example, the display portion 903 is held including a curved portion with a curvature radius of 1 mm to 50 mm, preferably 5 mm to 30 mm. Part of the display portion 903 can display a curved surface by continuously arranging pixels from the housing 901 to the housing 902.

The display portion 903 functions as a touch panel and can be operated with a finger or a stylus.

The display unit 903 is preferably composed of one flexible display. Accordingly, it is possible to perform continuous display without interruption between the housing 901 and the housing 902. Note that a display may be provided in each of the housing 901 and the housing 902.

The hinge unit 905 preferably has a lock mechanism so that the angle between the housing 901 and the housing 902 does not become larger than a predetermined angle when the portable information terminal 900 is deployed. For example, it is preferable that the angle at which the lock is applied (not opened further) is 90 degrees or more and less than 180 degrees, typically 90 degrees, 120 degrees, 135 degrees, 150 degrees, or 175 degrees. be able to. Thereby, the convenience, safety | security, and reliability of the portable information terminal 900 can be improved.

When the hinge portion 905 has a lock mechanism, the display portion 903 can be prevented from being damaged without applying excessive force to the display portion 903. Therefore, a highly reliable portable information terminal can be realized.

The housing 901 and the housing 902 may include a power button, an operation button, an external connection port, a speaker, a microphone, and the like.

One of the housing 901 and the housing 902 is provided with a wireless communication module, and transmits and receives data via a computer network such as the Internet, a LAN (Local Area Network), and Wi-Fi (registered trademark). Is possible.

A portable information terminal 910 illustrated in FIG. 8C includes a housing 911, a display portion 912, operation buttons 913, an external connection port 914, a speaker 915, a microphone 916, a camera 917, and the like.

A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 912. Thereby, a portable information terminal can be manufactured with a high yield.

The portable information terminal 910 includes a touch sensor in the display unit 912. All operations such as making a call or inputting characters can be performed by touching the display portion 912 with a finger or a stylus.

Further, by operating the operation button 913, the power can be turned on and off, and the type of the image displayed on the display unit 912 can be switched. For example, the mail creation screen can be switched to the main menu screen.

Further, by providing a detection device such as a gyro sensor or an acceleration sensor inside the portable information terminal 910, the orientation (portrait or landscape) of the portable information terminal 910 is determined, and the screen display orientation of the display unit 912 is determined. It can be switched automatically. The screen display orientation can also be switched by touching the display portion 912, operating the operation buttons 913, or inputting voice using the microphone 916.

The portable information terminal 910 has one or a plurality of functions selected from, for example, a telephone, a notebook, an information browsing device, or the like. Specifically, it can be used as a smartphone. The portable information terminal 910 can execute various applications such as mobile phone, electronic mail, text browsing and creation, music playback, video playback, Internet communication, and games.

A camera 920 illustrated in FIG. 8D includes a housing 921, a display portion 922, operation buttons 923, a shutter button 924, and the like. A removable lens 926 is attached to the camera 920.

A light-emitting device manufactured using one embodiment of the present invention can be used for the display portion 922. Thereby, a camera can be manufactured with a high yield.

Here, the camera 920 is configured such that the lens 926 can be removed from the housing 921 and replaced, but the lens 926 and the housing 921 may be integrated.

The camera 920 can capture a still image or a moving image by pressing the shutter button 924. In addition, the display portion 922 has a function as a touch panel and can capture an image by touching the display portion 922.

The camera 920 can be separately attached with a strobe device, a viewfinder, and the like. Alternatively, these may be incorporated in the housing 921.

9A to 9E illustrate electronic devices. These electronic devices include a housing 9000, a display portion 9001, a speaker 9003, operation keys 9005 (including a power switch or an operation switch), a connection terminal 9006, and a sensor 9007 (force, displacement, position, speed, acceleration, angular velocity, rotation) Number, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, power, radiation, flow rate, humidity, gradient, vibration, smell, or infrared) And a microphone 9008 and the like.

A light-emitting device manufactured using one embodiment of the present invention can be favorably used for the display portion 9001. Thereby, an electronic device can be manufactured with a high yield.

The electronic devices illustrated in FIGS. 9A to 9E can have a variety of functions. For example, a function for displaying various information (still images, moving images, text images, etc.) on the display unit, a touch panel function, a function for displaying a calendar, date or time, a function for controlling processing by various software (programs), Wireless communication function, function for connecting to various computer networks using the wireless communication function, function for transmitting or receiving various data using the wireless communication function, and reading and displaying the program or data recorded on the recording medium It can have a function of displaying on the section. Note that the functions of the electronic devices illustrated in FIGS. 9A to 9E are not limited to these, and may have other functions.

9A is a perspective view illustrating a wristwatch-type portable information terminal 9200, and FIG. 9B is a perspective view illustrating a wristwatch-type portable information terminal 9201.

A portable information terminal 9200 illustrated in FIG. 9A can execute various applications such as a mobile phone, electronic mail, text browsing and creation, music playback, Internet communication, and computer games. Further, the display portion 9001 is provided with a curved display surface, and can perform display along the curved display surface. In addition, the portable information terminal 9200 can execute short-range wireless communication with a communication standard. For example, it is possible to talk hands-free by communicating with a headset capable of wireless communication. In addition, the portable information terminal 9200 includes a connection terminal 9006 and can directly exchange data with other information terminals via a connector. Charging can also be performed through the connection terminal 9006. Note that the charging operation may be performed by wireless power feeding without using the connection terminal 9006.

A mobile information terminal 9201 illustrated in FIG. 9B is different from the mobile information terminal illustrated in FIG. 9A in that the display surface of the display portion 9001 is not curved. In addition, the external shape of the display portion of the portable information terminal 9201 is a non-rectangular shape (a circular shape in FIG. 9B).

9C to 9E are perspective views showing a foldable portable information terminal 9202. FIG. 9C is a perspective view of a state in which the portable information terminal 9202 is expanded, and FIG. 9D is a state in which the portable information terminal 9202 is expanded or changed from one of the folded state to the other. FIG. 9E is a perspective view of the portable information terminal 9202 folded.

The portable information terminal 9202 is excellent in portability in the folded state, and in the expanded state, the portable information terminal 9202 is excellent in display listability due to a seamless wide display area. A display portion 9001 included in the portable information terminal 9202 is supported by three housings 9000 connected by a hinge 9055. By bending between the two housings 9000 via the hinge 9055, the portable information terminal 9202 can be reversibly deformed from the expanded state to the folded state. For example, the portable information terminal 9202 can be bent with a curvature radius of 1 mm to 150 mm.

This embodiment can be combined with any of the other embodiments as appropriate.

(Embodiment 5)
In this embodiment, examples of applying the light-emitting element of one embodiment of the present invention to various lighting devices will be described with reference to FIGS. By using the light-emitting element which is one embodiment of the present invention, a highly reliable lighting device with favorable light emission efficiency can be manufactured.

By manufacturing the light-emitting element of one embodiment of the present invention over a flexible substrate, an electronic device or a lighting device having a light-emitting region having a curved surface can be realized.

In addition, the light-emitting device to which the light-emitting element of one embodiment of the present invention is applied can also be used for lighting of a car, for example, lighting can be installed on a windshield, a ceiling, or the like.

10A shows a perspective view of one surface of the multi-function terminal 3500, and FIG. 10B shows a perspective view of the other surface of the multi-function terminal 3500. In the multi-function terminal 3500, a display portion 3504, a camera 3506, an illumination 3508, and the like are incorporated in a housing 3502. The light-emitting device of one embodiment of the present invention can be used for the lighting 3508.

The illumination 3508 functions as a surface light source by using the light-emitting device of one embodiment of the present invention. Therefore, unlike a point light source typified by an LED, light emission with less directivity can be obtained. For example, when the lighting 3508 and the camera 3506 are used in combination, the lighting 3508 can be turned on or blinked and an image can be captured by the camera 3506. Since the illumination 3508 has a function as a surface light source, it can capture a photograph taken under natural light.

Note that the multi-function terminal 3500 illustrated in FIGS. 10A and 10B can have various functions similar to the electronic devices illustrated in FIGS. 9A to 9C.

In addition, a speaker, a sensor (force, displacement, position, velocity, acceleration, angular velocity, rotation speed, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current are provided inside the housing 3502. , Voltage, power, radiation, flow rate, humidity, gradient, vibration, odor or infrared measurement function), microphone, and the like. Further, by providing a detection device having a sensor for detecting inclination such as a gyroscope and an acceleration sensor inside the multi-function terminal 3500, the orientation (vertical or horizontal) of the multi-function terminal 3500 is determined, and a display unit 3504 is provided. The screen display can be automatically switched.

The display portion 3504 can also function as an image sensor. For example, personal authentication can be performed by touching the display portion 3504 with a palm or a finger and capturing a palm print, a fingerprint, or the like. In addition, when a backlight that emits near-infrared light or a sensing light source that emits near-infrared light is used for the display portion 3504, finger veins, palm veins, and the like can be imaged. Note that the light-emitting device of one embodiment of the present invention may be applied to the display portion 3504.

FIG. 10C is a perspective view of a crime prevention light 3600. FIG. The light 3600 includes an illumination 3608 outside the housing 3602, and the housing 3602 incorporates a speaker 3610 and the like. The light-emitting element of one embodiment of the present invention can be used for the lighting 3608.

As the light 3600, for example, light can be emitted by holding, holding, or holding the illumination 3608. Further, an electronic circuit that can control a light emission method from the light 3600 may be provided inside the housing 3602. As the electronic circuit, for example, a circuit that can emit light once or intermittently a plurality of times may be used, or a circuit that can adjust the light emission amount by controlling the light emission current value. Good. In addition, a circuit that outputs a loud alarm sound from the speaker 3610 at the same time as the light emission of the illumination 3608 may be incorporated.

Since the light 3600 can emit light in all directions, for example, it can be threatened with light or light and sound toward a thief or the like. The light 3600 may be provided with a camera such as a digital still camera and a function having a photographing function.

FIG. 11 shows an example in which a light-emitting element is used as an indoor lighting device 8501. Note that since the light-emitting element can have a large area, a large-area lighting device can be formed. In addition, by using a housing having a curved surface, the lighting device 8502 in which the light-emitting region has a curved surface can be formed. The light-emitting element described in this embodiment is thin and has a high degree of freedom in housing design. Therefore, it is possible to form a lighting device with various designs. Further, a large lighting device 8503 may be provided on the indoor wall surface. Alternatively, the

lighting devices

8501, 8502, and 8503 may be provided with touch sensors to turn the power on or off.

Moreover, it can be set as the illuminating device 8504 provided with the function as a table by using a light emitting element for the surface side of a table. Note that a lighting device having a function as furniture can be obtained by using a light-emitting element as part of other furniture.

As described above, a lighting device and an electronic device can be obtained by using the light-emitting device of one embodiment of the present invention. Note that applicable lighting devices and electronic devices are not limited to those described in this embodiment and can be applied to electronic devices in various fields.

The structure described in this embodiment can be combined as appropriate with any of the structures described in the other embodiments.

In this example, a manufacturing example of a light-emitting element according to one embodiment of the present invention and characteristics of the light-emitting element will be described. In addition, measurement results of MS / MS analysis for the host material of the light-emitting element will be described. A cross-sectional view of the element structure manufactured in this embodiment is shown in FIG. Details of the element structure are shown in Table 1. The structures and abbreviations of the compounds used are shown below.

<Production of light-emitting element>
<< Production of Light-Emitting Element 1 >>
An ITSO film having a thickness of 70 nm was formed as an electrode 101 on a glass substrate. The electrode area of the electrode 101 was 4 mm ² (2 mm × 2 mm).

Next, as a hole injection layer 111 over the

electrode

101, 1,3,5-tri- (4-dibenzothiophenyl) -benzene (abbreviation: DBT3P-II) and MoO ₃ are mixed in a weight ratio (DBT3P— II: MoO ₃ ) was co-deposited so that the ratio was 1: 0.5 and the thickness was 60 nm.

Next, 4-phenyl-4 ′-(9-phenylfluoren-9-yl) triphenylamine (abbreviation: BPAFLP) is formed to a thickness of 20 nm as the hole transport layer 112 over the hole injection layer 111. Vapor deposited.

Next, 2- {3- [3- (benzo [b] naphtho [1,2-d] furan-8-yl) phenyl] phenyl}-is formed as the light-emitting layer 130 (1) over the hole-transport layer 112. 4,6-diphenyl-1,3,5-triazine (abbreviation: mBnfBPTZn) and N- (1,1′-biphenyl-4-yl) -9,9-dimethyl-N- [4- (9-phenyl) -9H-carbazol-3-yl) phenyl] -9H-fluoren-2-amine (abbreviation: PCBBiF) and bis [2- (6-phenyl-4-pyrimidinyl-κN ³ ) phenyl-κC] (2,4 -Pentandionato-κ2O, O ′) Iridium (III) (abbreviation: Ir (dppm) ₂ (acac)) with a weight ratio of mBnfBPTzn: PCBBiF: Ir (dppm) ₂ (acac) = 0.7: 0.3 : 0.05 Made way, and thickness were co-deposited so as to 20 nm, followed by a light-emitting layer 130 (2), the weight ratio _{(mBnfBPTzn: PCBBiF: Ir (dppm} ) 2 (acac)) is 0.8: 0. 2: Co-deposition was performed so that the thickness was 0.05 and the thickness was 20 nm. Note that in the light-emitting layer 130 (1) and the light-emitting layer 130 (2), Ir (dppm) ₂ (acac) is a guest material that emits phosphorescence.

Next, mBnfBPTZ was co-deposited on the light emitting layer 130 (2) so as to have a thickness of 20 nm as the first electron transporting layer 118- (1). Subsequently, bathophenanthroline (abbreviation: BPhen) was deposited on the first electron transport layer 118- (1) as the second electron transport layer 118- (2) so as to have a thickness of 10 nm.

Next, lithium fluoride (LiF) was deposited as an electron injection layer 119 on the second electron transport layer 118- (2) so as to have a thickness of 1 nm.

Next, aluminum (Al) was formed as an electrode 102 on the electron injection layer 119 so as to have a thickness of 200 nm.

Next, the light emitting element 1 was sealed by fixing the glass substrate for sealing using the sealing material for organic EL in the glove box of nitrogen atmosphere to the glass substrate in which the organic material was formed. Specifically, a sealing material is applied around the organic material on the glass substrate on which the organic material is formed, the substrate and the glass substrate for sealing are bonded, and ultraviolet light with a wavelength of 365 nm is applied to 6 J / Irradiated with cm ² and heat-treated at 80 ° C. for 1 hour. The light emitting element 1 was obtained through the above steps.

<MS / MS analysis 1 of light emitting element>
Next, MS / MS analysis was performed on the EL layer of the light-emitting element 1. The analysis was performed with a MALDI-TOFMS apparatus (model number: JMS-S3000) equipped with a linear TOF option (model number: MS-50620LNR) manufactured by JEOL Ltd. and a TOF / TOF option (model number: MS-50610TT). He was used as the collision gas. Measurement was performed in positive mode.

FIG. 12 shows an MS / MS measurement result regarding a component in the vicinity of m / z = 601 that is an ion derived from mBnfBPTzn, which is the host material of the light-emitting element 1.

The molecular structure attributed to each peak in FIG. 12 is shown below.

Regarding FIG. 12, the peak observed around m / z = 602 is a peak derived from mBnfBPTzn, which is a precursor ion. The fragment ion peak observed near m / z = 104 is attributed to a cation formed by cleavage of the triazine ring in mBnfBPTzn, and this fragment is attributed to have a C═N bond derived from a phenyl group and a triazine ring. .

<Characteristics of light emitting element>
Next, characteristics of the manufactured light-emitting element 1 were measured. A color luminance meter (Top-5, BM-5A) was used for measurement of luminance and CIE chromaticity, and a multi-channel spectrometer (PMA-11, manufactured by Hamamatsu Photonics) was used for measurement of electroluminescence spectrum.

FIG. 13 shows current efficiency-luminance characteristics of the light-emitting element 1. Further, FIG. 14 shows current density-voltage characteristics. Further, FIG. 15 shows the external quantum efficiency-luminance characteristics. Note that each light-emitting element was measured at room temperature (atmosphere kept at 23 ° C.).

In addition, FIG. 16 shows an emission spectrum when current is passed through the light-emitting element 1 at a current density of 25 mA / cm ² . As shown in FIG. 16, the emission spectrum of the light-emitting element 1 has a peak near 585 nm and is derived from light emission of Ir (dppm) ₂ (acac), which is a guest material included in the light-emitting layer 130. I understood it.

Table 2 shows element characteristics of the light-emitting element 1 around 1000 cd / m ² .

From the above results, it can be seen that the light-emitting element 1 manufactured in this example exhibits good driving voltage, current efficiency, and external quantum efficiency.

Next, the light emitting element 1 was subjected to a constant current driving test at 2 mA. The result is shown in FIG. From FIG. 17, the luminance half life of the light-emitting element 1 showed a good value exceeding 500 hours.

As described above, a light-emitting element that includes an organic compound having a nitrogen-containing heteroaromatic ring containing two or more nitrogen atoms and in which fragment ions having a C═N bond are observed when performing MS / MS analysis in a positive mode is favorable. It was found that the device characteristics were exhibited.

In this example, a result obtained by analyzing the light-emitting element 1 by MS / MS measurement different from that in Example 1 will be described.

<MS / MS analysis 2 of light emitting element>
The EL layer of the light-emitting element 1 was subjected to MS / MS analysis by a method different from the method described in Example 1. In MS / MS analysis, ionization by electrospray ionization (ElectroSpray Ionization, abbreviation: ESI) was performed, and measurement was performed by the Targeted-MS2 method. The ion source settings are 50 sheath gas flow rate, 10 Aux gas flow rate, 0 sweep gas flow rate, 0 spray voltage, 3.5 kV, capillary temperature is 380 ° C, S lens voltage is 55.0, and HESI heater temperature is 350 ° C. And detection was performed in positive mode.

Fragmentation was caused by colliding a component of m / z = 602 ± 2 ionized under the above conditions with nitrogen gas in a collision chamber (collision cell), and MS / MS analysis was performed. The energy NCE (Normalized Collision Energy) for accelerating ions when colliding with nitrogen was set to 40, and the generated ions were detected by a Fourier transform mass spectrometer (FT MS).

The measurement sample was adjusted by dissolving the EL layer of the light-emitting element 1 in a mixed solution of acetonitrile: chloroform = 7: 3.

FIG. 18 shows an MS / MS measurement result regarding a component in the vicinity of m / z = 602, which is an ion derived from mBnfBPTzn, which is the host material of the light-emitting element 1.

The molecular structure attributed to each peak in FIG. 18 is shown below.

From the results of FIG. 18, it was found that mBnfBPTZn mainly detects product ions in the vicinity of m / z = 602, 396, and 104. The peak near m / z = 602 is a peak derived from mBnfBPTzn, which is a precursor ion. Fragment ions detected in the vicinity of m / z = 396 and 104 are attributed to cations generated by cleavage of the triazine ring in mBnfBPTzn. A fragment ion near m / z = 396 is attributed to a cation having a biphenylbenzonaphthofuranyl group and a C═N bond, which mBnfBPTzn has. Moreover, the fragment ion detected in the vicinity of m / z = 104 is attributed to a cation having a phenyl group and a C═N bond, which mBnfBPTzn has.

In addition, the peak intensity of a cation having a phenyl group and a C = N bond in the vicinity of m / z = 104 is obtained with an intensity of 100 times or more compared to the peak intensity of a precursor ion in the vicinity of m / z = 602. I understand. This is a characteristic observed when an organic compound having a triazine ring is analyzed under the above measurement conditions. That is, when an organic compound is measured under the above measurement conditions, fragment ions attributed as having a C═N bond are observed, and when the peak intensity is obtained at an intensity 100 times or more that of the precursor ion, MS / It is presumed that the organic compound that is the object of measurement of MS contains a triazine ring. Note that the above characteristics are also observed when measurement is performed at an NCE of 35 to 60 and an acceleration voltage corresponding thereto. This is a characteristic that is not observed when measured under the conditions of Example 1.

As described above, even when the light-emitting element 1 is analyzed by an MS / MS analysis method different from that in Example 1, an MS / MS analysis is performed on an organic compound having a nitrogen-containing heteroaromatic hydrocarbon group containing two or more nitrogen atoms. It was found that fragment ions having a C = N bond were observed.

In this example, MS / MS measurement of an organic compound different from the organic compounds exemplified in Example 1 and Example 2 and the measurement result will be described.

The names and structures of organic compounds subjected to MS / MS measurement are shown below.

<MS / MS analysis of T2T>
The MS / MS measurement of 2,4,6-tris (biphenyl-3-yl) -1,3,5-triazine (abbreviation: T2T) will be described. T2T is an organic compound that can be suitably used as a host material of a light-emitting element. Measurements were made on components with ionized m / z = 538 ± 2. The measurement method was the same as that described in Example 2. The measurement conditions differed only in the value of NCE, and measurement was performed at NCE = 35. The measurement results are shown in FIG.

The molecular structure belonging to each peak in FIG. 19 is shown below.

From the results of FIG. 19, it was found that T2T mainly detects product ions near m / z = 538 and around 180. The peak near m / z = 538 is a peak derived from T2T, which is a precursor ion. Fragment ions detected in the vicinity of m / z = 180 are attributed to cations generated by cleavage of the triazine ring in T2T. This fragment ion near m / z = 180 is attributed to a cation having a biphenyl group and a C═N bond, which T2T has.

In addition, the peak intensity of a cation having a biphenyl group near C / N = 180 and m / z = 180 is obtained with an intensity of 100 times or more compared to the peak intensity of a precursor ion near m / z = 538. I understand that. As described in Example 2, this is a characteristic observed when an organic compound having a triazine ring is analyzed under the above measurement conditions.

<MS / MS analysis of TmPPPyTz>
An MS / MS measurement of 2,4,6-tris (3 ′-(pyridin-3-yl) -biphenyl-3-yl) -1,3,5-triazine (abbreviation: TmPPPyTz) will be described. TmPPPyTz is an organic compound that can be suitably used as a host material of a light-emitting element. Measurements were made on components with ionized m / z = 769 ± 2. The measurement method and measurement conditions were the same as those described in Example 2. The names and structures of organic compounds subjected to MS / MS measurement are shown below. The measurement results are shown in FIG.

The molecular structure attributed to each peak in FIG. 20 is shown below.

From the results of FIG. 20, it was found that TmPPyTz mainly detects product ions in the vicinity of m / z = 769 and 257. The peak near m / z = 769 is a peak derived from TmPPPyTz which is a precursor ion. The fragment ion detected in the vicinity of m / z = 257 is attributed to a cation generated by cleavage of the triazine ring in TmPPPyTz. This fragment ion near m / z = 257 is attributed to a cation having a biphenyl group and a C═N bond, which TmPPPyTz has.

In addition, the peak intensity of a cation having a biphenyl group near C / N and a C = N bond in the vicinity of m / z = 257 is obtained with an intensity of 100 times or more compared with the peak intensity of a precursor ion in the vicinity of m / z = 769. I understand. As described in Example 2, this is a characteristic observed when an organic compound having a triazine ring is analyzed under the above measurement conditions.

<MS / MS analysis of CzTAZ (1H)>
MS / MS measurement of 1- (4- (9H-carbazol-9-yl) -phenyl-1-yl) -2,4-

biphe

1,2,4-1H-triazole (abbreviation: CzTAZ (1H)) explain. CzTAZ (1H) is an organic compound that can be suitably used as a host material of a light-emitting element. Measurements were made on the ionized m / z = 463 ± 2 component. The measurement method was the method described in Example 2. The measurement conditions differed only in the value of NCE, and measurement was performed at NCE = 60. The names and structures of organic compounds subjected to MS / MS measurement are shown below. The measurement results are shown in FIG.

The molecular structure attributed to each peak in FIG. 21 is shown below.

From the results of FIG. 21, it was found that CzTAZ (1H) mainly detects product ions in the vicinity of m / z = 463, 360, 194, 166, and 104. The peak near m / z = 463 is a peak derived from CzTAZ (1H) which is a precursor ion. Fragment ions detected in the vicinity of m / z = 360 are attributed to cations generated by cleavage of the triazole ring in CzTAZ (1H). The fragment ion in the vicinity of m / z = 104 is attributed to a cation formed by cleavage of the triazole ring and dissociation of carbazole in CzTAZ (1H). A fragment ion near m / z = 166 is attributed to a cation derived from a carbazole group possessed by CzTAZ (1H).

A fragment ion detected in the vicinity of m / z = 104 is attributed to a cation having a phenyl group and a C═N bond, which CzTAZ (1H) has.

As described above, when an MS / MS analysis is performed on an organic compound having a triazine ring or a triazole ring and which can be suitably used for a light-emitting element, a fragment ion having a C═N bond generated by cleavage of the ring is detected. I found out that

(Reference Example 1)
In this reference example, a method for synthesizing mBnfBPTzn used in Example 1 and Example 2 will be described.

<Step 1: Synthesis of 1- (3-chloro-2-fluorophenyl) -2-naphthol>
In a 200 mL three-necked flask, 3.4 g (19 mmol) of 3-chloro-2-fluorophenylboronic acid, 4.0 g (18 mmol) of 1-bromo-2-naphthol, 0.13 g (0.36 mmol) of di ( 1-adamantyl) -n-butylphosphine and 7.6 g (72 mmol) of sodium carbonate were added, and the atmosphere in the flask was replaced with nitrogen. This mixture was deaerated by adding 90 mL of toluene and 36 mL of water and stirring the mixture under reduced pressure. After deaeration, 40 mg (0.18 mmol) of palladium (II) acetate was added to the mixture, and the mixture was stirred at about 80 ° C. for 15 hours. After stirring, the aqueous layer of this mixture was extracted with toluene, and the resulting extracted solution and the organic layer were combined and washed with saturated brine. The obtained organic layer was dried with magnesium sulfate. The mixture was naturally filtered, and the obtained filtrate was concentrated to give a brown oil. When this oily substance was purified by silica gel column chromatography (developing solvent: toluene), 4.5 g of the objective brown oily substance was obtained in a yield of 91%. The synthesis scheme of Step 1 is shown in the following formula (a-1).

<Step 2: Synthesis of 8-chlorobenzo [b] naphtho [1,2-d] furan>
Next, in a 500 mL three-necked flask, 4.5 g (16 mmol) of 1- (3-chloro-2-fluorophenyl) -2-naphthol, 80 mL of N-methyl-2-pyrrolidone (NMP), 4.4 g (32 mmol) of potassium carbonate was added. The flask was stirred at 150 ° C. for 2 hours under a nitrogen stream. After stirring, the mixture was allowed to cool to room temperature, then about 200 mL of toluene was added and the mixture was added to about 100 mL of water. The aqueous layer of this mixture was extracted with toluene, and the extracted solution and the organic layer were combined and washed with dilute hydrochloric acid (1.0 mol / L) and saturated brine. The organic layer was dried with magnesium sulfate, and after drying, the mixture was naturally filtered. When the obtained filtrate was concentrated, an oily substance was obtained. The obtained oily substance was dissolved in about 50 mL of toluene, and this solution was subjected to suction filtration through celite, alumina and Florisil. The solid obtained by concentrating the obtained filtrate was recrystallized with toluene / hexane to obtain 3.2 g of the objective white needle crystal in a yield of 79%. The synthesis scheme of Step 2 is shown by the following formula (a-2).

<Step 3: Synthesis of 4,4,5,5-tetramethyl-2- (benzo [b] naphtho [1,2-d] furan-8-yl) -1,3,2-dioxaborolane>
Next, in a 200 mL three-necked flask, 2.5 g (10 mmol) of 8-chlorobenzo [b] naphtho [1,2-d] furan, 3.0 g (12 mmol) of bis (pinacolato) diboron, 72 mg (0.20 mmol). ) Di (1-adamantyl) -n-butylphosphine and 3.0 g (30 mmol) of potassium acetate, and the atmosphere in the flask was replaced with nitrogen. To this mixture, 50 mL of xylene was added and degassed by stirring under reduced pressure. To this mixture, 82 mg (0.10 mmol) of [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct was added and stirred at 130 ° C. for 4 hours under a nitrogen stream. After stirring, the mixture was filtered with suction, and the obtained filtrate was concentrated to give an oil. The obtained oil was purified by silica gel column chromatography (developing solvent: hexane: toluene = 9: 1) to obtain a solid. When the obtained solid was washed with hexane, 2.0 g of a target white solid was obtained in a yield of 59%. The synthesis scheme of Step 3 is shown by the following formula (a-3).

<Step 4: Synthesis of 2- (3-chlorophenyl) -4,6-diphenyl-1,3,5-triazine>
In a 200 mL three-necked flask, 10 g (37 mmol) 2-chloro-4,6-diphenyl-1,3,5-triazine, 5.8 g (37 mmol) 3-chlorophenylboronic acid, and 7.8 g (74 mmol) carbonic acid. Sodium was added and the atmosphere in the flask was replaced with nitrogen. To this mixture, 150 mL of toluene, 35 mL of ethanol, and 37 mL of water were added, and degassed by stirring while reducing the pressure. After deaeration, 0.43 g (0.37 mmol) of tetrakis (triphenylphosphine) palladium (0) was added to the mixture, and the mixture was stirred at about 80 ° C. for 3 hours. After stirring, the aqueous layer of this mixture was extracted with toluene, and the resulting extracted solution and the organic layer were combined and washed with saturated brine. The obtained organic layer was dried with magnesium sulfate. This mixture was naturally filtered, and the obtained filtrate was concentrated to obtain a solid. The obtained solid was dissolved in about 30 mL of heated toluene, and this solution was subjected to suction filtration through celite, alumina and Florisil. The obtained filtrate was concentrated and washed with solid methanol obtained, and this solid was collected by suction filtration. As a result, 11 g of the desired white solid was obtained in a yield of 86%. The synthesis scheme of Step 4 is shown by the following formula (a-4).

<Step 5: of 4,4,5,5-tetramethyl-2- [3- (4,6-diphenyl-1,3,5-triazin-2-yl) phenyl] -1,3,2-dioxaborolane Synthesis>
In a 200 mL three-necked flask, 5.0 g (15 mmol) of 2- (3-chlorophenyl) -4,6-diphenyl-1,3,5-triazine, 4.1 g (16 mmol) of bis (pinacolato) diboron, 21 g (0.60 mmol) of di (1-adamantyl) -n-butylphosphine and 4.4 g (45 mmol) of potassium acetate were added, and the atmosphere in the flask was replaced with nitrogen. To this mixture, 74 mL of xylene was added and degassed by stirring under reduced pressure. The mixture was heated to 40 ° C., 0.12 g (0.15 mmol) of [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct was added, and the nitrogen mixture was flowed at 130 ° C. Stir for 24 hours. After stirring, the mixture was filtered with suction, and the obtained filtrate was concentrated to give an oil. The obtained oil was purified by silica gel column chromatography (developing solvent: hexane: toluene = 6: 1) to obtain a white solid. When the obtained solid was washed with hexane, 3.4 g of the target white solid was obtained in a yield of 53%. The synthesis scheme of Step 5 is shown by the following formula (a-5).

<Step 6: Synthesis of 2- [3- (3-chlorophenyl) phenyl] -4,6-diphenyl-1,3,5-triazine>
In a 200 mL three-neck flask, 3.0 g (6.9 mmol) of 4,4,5,5-tetramethyl-2- [3- (4,6-diphenyl-1,3,5-triazin-2-yl) phenyl] -1,3,2-dioxaborolane, 2.4 g (10 mmol) of 3-chloroiodobenzene, 43 mg (0.14 mmol) of tri (o-tolyl) phosphine, and 1.9 g (14 mmol) of potassium carbonate. The flask was purged with nitrogen. To this mixture, 25 mL of toluene, 10 mL of ethanol, and 7.0 mL of water were added, and degassed by stirring under reduced pressure. After deaeration, the mixture was heated at 40 ° C., 16 mg (0.070 mmol) of palladium (II) acetate was added, and the mixture was stirred at about 80 ° C. for 7 hours. As a result, a solid precipitated. The precipitated solid was collected by suction filtration, dissolved in about 30 mL of heated toluene, and suction filtered through celite, alumina, and Florisil. The solid obtained by concentrating the obtained filtrate was recrystallized with toluene to obtain 2.2 g of a target white solid in a yield of 77%. The synthesis scheme of Step 6 is shown by the following formula (a-6).

<Step 7: 2- {3- [3- (benzo [b] naphtho [1,2-d] furan-8-yl) phenyl] phenyl} -4,6-diphenyl-1,3,5-triazine Synthesis>
In a 200 mL three-necked flask, 2.1 g (5.0 mmol) of 2- [3- (3-chlorophenyl) phenyl] -4,6-diphenyl-1,3,5-triazine and 1.7 g (5.0 mmol) of 4,4,5,5-tetramethyl-2- (benzo [b] naphtho [1,2-d] furan-8-yl) -1,3,2-dioxaborolane and 3.2 g (15 mmol) of phosphorus Tripotassium acid and 36 mg (0.10 mmol) of di (1-adamantyl) -n-butylphosphine were added, and the atmosphere in the flask was replaced with nitrogen.

To this mixture was added 25 mL diethylene glycol dimethyl ether and 1.2 g (15 mmol) tert-butyl alcohol. The mixture was degassed by stirring it under reduced pressure. When 12 mg (0.050 mmol) of palladium (II) acetate was added to this mixture and the mixture was stirred at 80 ° C. for 7 hours under a nitrogen stream, a solid was precipitated.

After stirring, water was added to the mixture and stirred, and then the mixture was suction filtered to recover a solid. The collected solid was dissolved in about 500 mL of heated toluene, and this solution was subjected to suction filtration through Celite, alumina, and Florisil. The solid obtained by concentrating the obtained filtrate was recrystallized with toluene to obtain 1.8 g of a target white powder in a yield of 58%. The synthesis scheme of Step 7 is shown by the following formula (a-7).

Sublimation purification of 1.7 g of the obtained white powder was performed by a train sublimation method. The sublimation purification conditions were a white powder heated at 280 ° C. under a pressure of 0.018 Pa. After sublimation purification, 0.76 g of a white solid of mBnfBPTZn was obtained with a recovery rate of 44%.

The white solid obtained in Step 7 was measured by nuclear magnetic resonance spectroscopy ( ¹ H-NMR). The analysis results are shown below.

¹ H-NMR (CDCl ₃ , 500 MHz): δ = 7.56-7.64 (m, 8H), 7.79-7.85 (m, 6H), 7.90 (d, J = 9.0 Hz) , 1H), 7.96 (d, J = 8.5 Hz, 1H), 8.01-8.05 (m, 2H), 8.31 (s, 1H), 8.45 (d, J = 8 .5Hz, 1H), 8.70 (d, J = 8.0 Hz, 1H), 8.80-8.83 (m, 5H), 9.11 (s, 1H).

100 EL layer 101 Electrode 102 Electrode 106 Light emitting unit 108 Light emitting unit 110 Light emitting unit 111 Hole injection layer 112 Hole transport layer 113 Electron transport layer 114 Electron injection layer 115 Charge generation layer 116 Hole injection layer 117 Hole transport layer 118 Electron Transport layer 119 Electron injection layer 120 Light emitting layer 121 Guest material 122 Host material 130 Light emitting layer 131 Host material 132 Guest material 140 Light emitting layer 141 Guest material 142 Host material 142_1 Organic compound 142_2 Organic compound 150 Light emitting element 152 Light emitting element 170 Light emitting layer 180 EL Layer 200 Substrate 220 Substrate 250 Light-emitting element 252 Light-emitting element 300 Container 310 Solvent 320 Sample 601 Source-side drive circuit 602 Pixel portion 603 Gate-side drive circuit 604 Sealing substrate 605 Sealing material 607 Space 608 Wiring 610 Element substrate 611 Switching TFT
612 Current control TFT
613 Electrode 614 Insulator 616 EL layer 617 Electrode 618 Light-emitting element 623 n-channel TFT
624 p-channel TFT
900 Mobile information terminal 901 Case 902 Case 903 Display unit 905 Hinge unit 910 Mobile information terminal 911 Case 912 Display unit 913 Operation button 914 External connection port 915 Speaker 916 Microphone 917 Camera 920 Camera 921 Case 922 Display unit 923 Operation button 924 Shutter button 926 Lens 1001 Substrate 1002 Underlying insulating film 1003 Gate insulating film 1006 Gate electrode 1007 Gate electrode 1008 Gate electrode 1020 Interlayer insulating film 1021 Interlayer insulating film 1022 Electrode 1024B Electrode 1024G Electrode 1024R Electrode 1024W Electrode

1025B Lower electrode

1025G Lower electrode

1025R Lower Electrode

1025W Lower electrode 1026 Partition 1028 EL layer 1029 Electrode 1031 Sealing substrate 1032 Sealing material 1033 Substrate

1034B Colored layer

1034G Colored layer

1034R Colored layer 1036 Overcoat layer 1037 Interlayer insulating film 1040 Pixel portion 1041 Drive circuit portion 1042 Peripheral portion 3500 Multifunctional terminal 3502 Housing 3504 Display portion 3506 Camera 3508 Lighting 3600 Light 3602 Housing 3608 Lighting 3610 Speaker 8501 Lighting device 8502 Lighting device 8503 Lighting device 8504 Lighting device 9000 Housing 9001 Display unit 9003 Speaker 9005 Operation key 9006 Connection terminal 9007 Sensor 9008 Microphone 9055 Hinge 9200 Portable information terminal 9201 Portable information terminal 9202 Portable information terminal

Claims

An EL layer between the pair of electrodes;
A light-emitting element in which fragment ions in which a structure represented by the following general formula (g0) is ionized are detected by performing MS / MS analysis on the EL layer.

(In the general formula (g0), Ar 1 to Ar 4 each independently represents a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 25 carbon atoms, and n 1 to n 4 each independently represents 0 or 1 and B 1 represents any one of hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms. , On carbon (C) and nitrogen (N) represents an unpaired electron.)
An EL layer between the pair of electrodes;
The light emitting element by which the fragment ion which the structure shown to the following general formula (g0) and general formula (g1) ionized is detected by performing MS / MS analysis about the said EL layer.

(In the general formulas (g0) and (g1), Ar 1 to Ar 8 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, n 1 to n 4 , m 1 to m 4 independently represents 0 or 1, and B 1 and B 2 each independently represent hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted carbon number 1 to Represents any one of 20 heteroaromatic hydrocarbon groups, and on carbon (C) and nitrogen (N) represents an unpaired electron.)
In claim 1 or claim 2,
The light-emitting element in which, in the general formulas (g0) and (g1), the Ar 1 to Ar 8 are substituted or unsubstituted phenyl groups.
In claim 1 or claim 2,
The light emitting element whose general formula (g0) is any one of the following structural formulas (100) to (103).

(In structural formulas (100) to (103), “on” carbon (C) and nitrogen (N) represents an unpaired electron.)
In claim 1 or claim 2,
The EL layer has an organic compound represented by the following general formula (G0),
The fragment ion is a light emitting element derived from the organic compound.

(In General Formula (G0), A represents a C1-C20 heteroaromatic hydrocarbon group containing two or more substituted or unsubstituted nitrogen atoms, and Ar 1 to Ar 12 are each independently substituted or unsubstituted. And n 1 to n 4 , m 1 to m 4 , and l 1 to l 4 each independently represents 0 or 1, and B 1 to B 3 each represents an aromatic hydrocarbon group having 6 to 25 carbon atoms Independently, it represents any one of hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms.
In claim 1 or claim 2,
The EL layer has an organic compound represented by the following general formula (G1),
The fragment ions are derived from the organic compound,
The general formula (g0) is a light-emitting element represented by the following structural formula (100).

(In General Formula (G1), A represents a heteroaromatic hydrocarbon group having 1 to 20 carbon atoms containing two or more substituted or unsubstituted nitrogen atoms, and Ar 5 to Ar 12 are each independently substituted or unsubstituted. And an aromatic hydrocarbon group having 6 to 25 carbon atoms, m 1 to m 4 and l 1 to l 4 each independently represents 0 or 1, and B 2 and B 3 are each independently hydrogen, substituted or This represents any one of an unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms or a substituted or unsubstituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, and in the structural formula (100), carbon (C) And on nitrogen (N) represents an unpaired electron.)
In claim 5,
The light emitting element in which the C1-C20 heteroaromatic hydrocarbon group containing two or more nitrogen atoms includes one or more of a triazine skeleton, a pyrimidine skeleton, an imidazole skeleton, and a triazole skeleton.
In claim 1 or claim 2,
The EL layer has any one of organic compounds represented by the following general formula (G2) or (G3),
The fragment ion is a light emitting element derived from the organic compound.

(In General Formulas (G2) and (G3), Ar 1 to Ar 12 each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, and n 1 to n 4 , m 1 to m 4 , l 1 to l 4 each independently represents 0 or 1, and B 1 to B 3 each independently represent hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted group. It represents any one of a substituted heteroaromatic hydrocarbon group having 1 to 20 carbon atoms, Q represents carbon or nitrogen, and when Q is carbon, Q may have a substituent. In addition, when Q is carbon and has no substituent, Q represents CH.)
In claim 1 or claim 2,
The EL layer has any one of organic compounds represented by the following general formula (G4) or (G5),
The fragment ions are derived from the organic compound,
The general formula (g0) is a light-emitting element represented by the following structural formula (100).

(In the general formulas (G4) and (G5), Ar 5 to Ar 12 each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, and m 1 to m 4 , l 1 to l 4 independently represents 0 or 1, and B 2 and B 3 each independently represent hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 25 carbon atoms, or a substituted or unsubstituted carbon number 1 to 20 represents any one of 20 heteroaromatic hydrocarbon groups, Q represents carbon or nitrogen, and when Q is carbon, Q may have a substituent, and Q is carbon. And Q represents CH, in the structural formula (100),. On the carbon (C) and nitrogen (N) represents an unpaired electron.)
In claim 1 or claim 2,
Dissolving the EL layer in a solvent;
A light emitting device in which the intensity of the MS spectrum of at least one fragment ion detected by the MS / MS analysis is detected with an intensity of 100 times or more compared to the intensity of the MS spectrum of the obtained precursor ion .
In claim 5,
The light emitting element whose molecular weight of the said organic compound is 300-1000.
In claim 5,
At least one of the B 2 and B 3 is a light-emitting element, which is a substituent having a substituted or unsubstituted dibenzofuran skeleton or a dibenzothiophene skeleton.
In claim 1 or claim 2,
The MS / MS analysis performs detection in positive mode,
The light-emitting element, wherein the fragment ion is a cation.
The light emitting device according to claim 1 or 2,
At least one of a color filter or a transistor;
A display device.
A display device according to claim 14,
At least one of a housing or a touch sensor;
Electronic equipment having
The light emitting device according to claim 1 or 2,
At least one of a housing or a touch sensor;
A lighting device.