JPWO2019163355A1 - Organic electroluminescence element, luminescent thin film, display device and lighting device - Google Patents

Abstract

The present invention provides an organic electroluminescence device, a luminescent thin film, a display device, and a lighting device, which exhibit high luminous efficiency and can extend the life of luminescence. The organic electroluminescence element includes an anode, a cathode, and a light emitting layer provided between the anode and the cathode, and the lowest excited single-term energy level and the lowest excited triple-term energy level are provided in the light emitting layer. Contains a compound having an energy difference of 0.5 eV or less and an aggregation-induced luminescent molecule. The luminescent thin film contains a compound having an energy difference of 0.5 eV or less between the lowest excited singlet energy level and the lowest excited triplet energy level and an aggregation-induced luminescent molecule. The display device and the lighting device are organic electros containing a compound having an energy difference of 0.5 eV or less between the lowest excited single-term energy level and the lowest excited triple-term energy level and an aggregation-induced luminescent molecule in the light emitting layer. It is equipped with a luminescence element.

Description

The present invention relates to an organic electroluminescence device, a luminescent thin film, a display device and a lighting device.

A display, which is a video display unit of a television or a computer, has become one of the indispensable electronic devices in modern society. In recent years, displays have been accelerating in size and thickness, and along with this, the development of organic electroluminescence (hereinafter, sometimes referred to as "organic EL") elements has also been active. Organic EL devices are self-luminous all-solid-state light-emitting devices with a relatively simple structure and a rich viewing angle, and have ideal characteristics as display components, so further spread is expected in the future. There is.

Generally, an organic EL element has a structure in which a functional thin film such as a light emitting layer is laminated between an anode and a cathode. An organic compound exhibiting luminescence is used for the light emitting layer provided between the anode and the cathode. When a voltage is applied between the anode and the cathode, the electrons injected from the cathode and the holes injected from the anode recombine on the luminescent compound contained in the light emitting layer to generate excitons. When these excitons are deactivated from the excited state to the ground state, energy is emitted as light to generate light.

In the development of organic EL devices, it is predicted that demands for price reduction, mass production, improvement of luminous efficiency and device life will increase more than ever. As a method for realizing low cost and mass production of organic EL devices, a wet coating method for forming a functional thin film by coating or printing a solution is considered to be effective. Therefore, at present, the development of a manufacturing process using a wet coating method instead of the vacuum vapor deposition method, which has been the mainstream in the past, is being widely promoted.

In addition, luminescent compounds used for the light emitting layer have also been studied from various viewpoints. As the luminescent compound, a fluorescent luminescent compound has been mainly used since the beginning of the development of the organic EL device. However, according to the recombination of electrons and holes, singlet excitons and triplet excitons are generated at a ratio of 1: 3 according to the spin-statistics rule. Therefore, in the fluorescent compound in which the transition from the singlet exciton contributes to light emission, the internal quantum efficiency is limited to 25% at the maximum.

On the other hand, it is now clear that a phosphorescent compound whose transition from triplet excitons contributes to light emission can theoretically achieve 100% internal quantum efficiency. As phosphorescent compounds, various phosphorescent metals that facilitate energy transfer from singlet excitons to triplet excitons (intersystem crossing: called ISC), which is originally prohibited, by the heavy atomic effect. Complexes have been developed. However, the phosphorescent metal complex that exhibits a short wavelength emission color such as blue has a shorter luminous life than other phosphorescent metal complexes that exhibit a long wavelength emission color. So far, an organic EL element having both luminous efficiency and element life at a high level has not been realized.

On the other hand, there is known a process that enables reverse energy transfer (reverse intersystem crossing: RISC) from triplet excitons to singlet excitons, which originally has a very low transition probability. Of these, energy transfer is promoted by minimizing the absolute value (hereinafter referred to as ΔE _st ) of the energy difference between the excited singlet energy level (S ₁ ) and the excited triplet energy level (T _1). There is a TADF (Thermally Activated Fluorescence) mechanism, and attempts have been made to improve the efficiency of excited element generation by utilizing these mechanisms.

For example, in Patent Document 1, in the light emitting layer of an organic EL element, a fluorescent light emitting material and a light emitting material exhibiting TADF (hereinafter referred to as TADF molecule) are used in combination to determine the light emitting efficiency of the organic EL element. Techniques for improvement are described. In Patent Document 1, a third material having a function as a dispersant is used together with these light emitting materials. It is said that the use of a third material having a function as a dispersant suppresses the energy loss of TADF molecules that easily cause molecular association and improves the efficiency of the light emitting device (see paragraph 0193).

Japanese Patent No. 5905916

From the viewpoint of improving the internal quantum efficiency of the organic EL device, a phosphorescent material that utilizes the radiation transition of triplet excitons for light emission is effective. However, the phosphorescent material has a drawback that the light emitting life does not reach a sufficient level, and in many cases, a rare precious metal is required. Therefore, a method of incorporating RISC into the process of energy transfer, converting triplet excitons into singlet excitons, and then emitting light is promising as an alternative technique or a complementary technique. However, in TADF molecules, the ISC process and RISC process usually compete with each other. Therefore, when the ISC rate constant is high and a large amount of triplet excitons are accumulated, the triplet excitons are quenched. There is a problem that deterioration is likely to proceed.

As described in Patent Document 1, such a triplet exciton quenching problem can be solved to some extent by using the TADF molecule as a material that mediates RISC, not as a light emitting material. it can. However, the luminescent compounds generally used in the past have a property of exhibiting strong luminescence when the molecules are isolated, and quenching when the concentration of the molecules becomes high and the molecules aggregate with each other. Even if the TADF molecule is used in combination, the luminescent compound that receives energy from the compound may still cause concentration extinction. Therefore, it is assumed that the concentration of the luminescent compound is increased with the aim of improving the luminous efficiency of the organic EL element. However, it is difficult to achieve high luminous efficiency.

Further, when a wet coating method is used to form a light-emitting layer, if the concentration of the luminescent compound in the solution used for coating is high, the molecules tend to aggregate with each other, so that the functionality of the light-emitting layer to be formed is functional. It is known that a thin film tends to have a local decrease in film density and a decrease in uniformity. Deterioration due to such aggregation also causes a decrease in luminous efficiency, but it is not easy to sufficiently prevent it by a dispersant as described in Patent Document 1.

Therefore, an object of the present invention is to provide an organic electroluminescence device, a luminescent thin film, a display device, and a lighting device, which exhibit high luminous efficiency and can prolong the life of luminescence.

The above-mentioned problems according to the present invention are solved by the following means.

1. 1. It includes an anode, a cathode, and a light emitting layer provided between the anode and the cathode, and the energy difference between the lowest excited single-term energy level and the lowest excited triple-term energy level is 0 in the light emitting layer. An organic electroluminescence device containing a compound having a concentration of .5 eV or less and an aggregation-induced luminescent molecule.

［但し、一般式（Ａ）中、Ａは、電子のアクセプター部位を表し、Ｄは、電子のドナー部位を表し、Ｌは、２価の連結基を表し、ｌ及びｍは、それぞれ独立して、１〜４の整数を表す。］2. The organic electroluminescence device according to claim 1, wherein the compound is a conjugated compound represented by the following general formula (A).

[However, in the general formula (A), A represents an electron acceptor site, D represents an electron donor site, L represents a divalent linking group, and l and m are independent of each other. , Represents an integer of 1-4. ]

3. 3. The organic electroluminescence device according to 1 above, wherein the aggregation-induced luminescent molecule is a tetraphenylethylene derivative or a siror derivative.

4. A luminescent thin film containing a compound having an energy difference of 0.5 eV or less between the lowest excited singlet energy level and the lowest excited triplet energy level and aggregation-induced luminescent molecules.

5. A display device including the organic electroluminescence element according to any one of 1 to 3 above.

A lighting device including the organic electroluminescence element according to any one of 1 to 3 above.

According to the present invention, it is possible to provide an organic electroluminescence element, a luminescent thin film, a display device and a lighting device, which exhibit high luminous efficiency and can extend the life of luminescence.

It is a conceptual diagram explaining the aggregation-induced luminescence of an AIE molecule. It is a schematic diagram which showed an example of the display device composed of an organic EL element. It is a schematic diagram of the display unit A. It is a schematic diagram of a pixel. It is a schematic diagram of a passive matrix type full-color display device. It is a schematic diagram of a lighting device. It is a schematic diagram of a lighting device.

Hereinafter, embodiments for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

As a result of diligent studies to achieve both emission efficiency and emission lifetime of organic EL elements and luminescent thin films, the present inventors have found aggregate-induced emission (AIE) molecules that exhibit stronger emission due to aggregation. When _{used in combination with a compound having a small ΔE st} , even if the concentration of the luminescent compound is increased to some extent, the problem of concentration quenching that occurs with conventional fluorescent compounds is alleviated, and the entire organic EL element or luminescent thin film is used. It has been found that the life of the luminescent compound is extended and the luminescence efficiency of the luminescent compound as a whole is also improved.

When a conventional fluorescent luminescent compound is used as the luminescent compound, it is known that if the concentration of the compound is increased with the aim of improving the luminous efficiency, concentration quenching occurs and the luminous efficiency is rather lowered. On the other hand, when AIE molecules are used as the luminescent compound, when the concentration of the compound is increased, strong luminescence is generated due to the aggregation of the molecules. Further, since a _{compound having a small ΔE st} is used in combination, RISC is promoted, and the utilization efficiency of triplet excitons, which are easily quenched, is also increased. Therefore, techniques using both the AIE molecules and Delta] E _st small compound as a luminescent compound is considered to be an effective means to achieve both emission efficiency and emission lifetime.

Further, it is generally known that a change over time in the film structure that occurs in the light emitting layer or the like is one of the causes of deterioration of the organic EL element or the like. Usually, when the molecules of the luminescent compound are diffused by applying a voltage, the molecules are aggregated and crystallized, and the film structure of the functional thin film such as the light emitting layer can be changed. It is considered that such a change in the film structure also affects the luminous efficiency of the organic EL element or the like as a whole. On the other hand, since AIE molecules can exhibit strong light emission in an aggregated state, changes in the film structure due to application of voltage are reduced by forming aggregates in advance before the molecules start diffusing. be able to. According to this method, there is an advantage that the film structure can be kept stable even when driving for a long period of time.

In addition, since AIE molecules can exhibit strong light emission in an aggregated state, it is possible to reduce contact with oxygen, moisture, etc. in the atmosphere by forming aggregates in advance. It is presumed that the formation of the agglomerates reduces the contact area with oxygen, moisture, etc., which are deterioration factors of the organic EL device and the like, and improves the stability of the luminescent compound in the atmosphere. Therefore, when sealing an organic EL element or the like, it is possible to use a sealing material having lower performance than before, which is expected to lead to cost reduction.

<< Organic EL element >>
First, the organic EL element according to the present embodiment will be described. The organic EL device according to the present embodiment includes an anode, a cathode, and a functional thin film arranged between the anode and the cathode and including at least a light emitting layer. _{In this organic EL element, the energy difference (ΔE st} ) between the lowest excited singlet energy level and the lowest excited triplet energy level is 0.5 eV or less in the light emitting layer provided between the anode and the cathode. , A compound having a property of easily producing RISC (hereinafter referred to as RISC compound) and an aggregation-induced luminescent molecule.

<Aggregation-induced luminescent molecule (AIE molecule)>
Aggregation-induced luminescent molecules (AIE molecules) do not emit light because the quantum yield is low or the emission intensity is weak when the molecules are dissolved or dispersed in the liquid medium without agglomeration. In a state where the molecules are aggregated to form an aggregate, the molecule exhibits a property that the quantum yield is high and the emission intensity is strong.

In the organic EL device according to the present embodiment, an appropriate molecule exhibiting the above-mentioned properties can be used as the AIE molecule. The type of AIE molecule is not particularly limited. As the AIE molecule, one type may be used alone or a plurality of types may be used in combination in a single light emitting layer. A preferred form of the AIE molecule is a molecule having at least one of an aromatic hydrocarbon ring and an aromatic heterocycle.

Specific examples of the AIE molecule include a benzoflo-oxazolo-carbazole-based aggregation-induced luminescent molecule, a carbolan-based aggregation-induced luminescent molecule, a tetraphenylethylene-based aggregation-induced luminescent molecule, a silol-based aggregation-induced luminescent molecule, and a rhodamine-based molecule. In addition to aggregation-induced luminescent molecules, aromatic ring-containing metal complexes in which a site that suppresses molecular movement is introduced into a ligand, other heterocompounds having an aromatic heterocycle, and the like can be mentioned. However, the types of AIE molecules are not limited to these.

(Benzoflo-oxazolo-carbazole-based aggregation-induced luminescent molecule)
The benzoflo-oxazolo-carbazole-based aggregation-induced luminescent molecule is a benzoflo-oxazolo-carbazole derivative having a benzoflo [2,3-c] oxazolo [4,5-a] carbazole skeleton represented by the following general formula (1). Can be used.

[However, in the general formula (1), R ₁ and R ₂ independently represent a hydrogen atom or a substituent, R ₃ and R ₄ independently represent a substituent, and m is. It represents an integer from 0 to 4, and n represents an integer from 0 to 4. ]

Examples of the substituent that replaces the benzoflo-oxazolo-carbazole derivative include various electron donating groups and electron attracting groups that exhibit an arbitrary substituent constant according to Hammett's rule, and in particular, an aliphatic hydrocarbon group and an aromatic group. A hydrocarbon group or a heterocyclic group is preferable.

Examples of the aliphatic hydrocarbon group substituting the benzoflo-oxazolo-carbazole derivative include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group and a tert-butyl group. , Pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group and other linear or branched alkyl groups, and cyclopentyl group, cyclohexyl group and other cycloalkyl groups.

Examples of the aromatic hydrocarbon group substituting the benzoflo-oxazolo-carbazole derivative include a phenyl group, a mesityl group, a trill group, a xylyl group, a naphthyl group, an anthryl group, an azulenyl group, an acenaphthenyl group, a fluorenyl group, a phenanthryl group and an indenyl group. Examples include a group, a pyrenyl group, a biphenylyl group and the like.

Examples of the heterocyclic group substituting the benzoflo-oxazolo-carbazole derivative include a pyridyl group, a pyridadyl group, a pyrimidinyl group, a pyrrolyl group, an imidazolyl group, a benzoimidazolyl group, a pyrazolyl group, a pyrazinyl group, a triazolyl group, a tetrazolyl group and an oxazolyl group. Thiazolyl group, benzoxazolyl group, benzothiazolyl group, isooxazolyl group, isothiazolyl group, thiadiazolyl group, oxadiazolyl group, furyl group, frazayl group, thienyl group, quinolyl group, isoquinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, Aromatic heterocyclic groups such as dibenzothienyl group, indazolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group, quinoxalinyl group, phenanthridyl group, pyridadinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, and pyrrolidyl group. , Non-aromatic heterocyclic groups such as imidazolidyl group, morpholic group, oxazolidyl group and the like.

The benzoflo-oxazolo-carbazole derivative includes, for example, a sulfonic acid group, a carboxyl group, a phosphoric acid group, a phosphite group, a hydroxyl group, an amino group, an isocyanate group, a silyl group, a halogen atom, an alkyl group, a cycloalkyl group and an alkenyl group. Alkinyl group, cycloalkenyl group, cycloalkynyl group, aryl group, aralkyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkoxycarbonyl group, aryloxycarbonyl group, sulfamoyl group, acyl group, acyloxy group, amide group , Carbamoyl group, ureido group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, cyano group, nitro group, mercapto group and other substituents, the skeleton itself represented by the general formula (1). Or, it may have an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group substituted on the skeleton thereof.

(Carborane-based aggregation-induced luminescent molecule)
The carborane-based aggregation induced luminescence _molecules, can be used 1, 2-closo radical Bud derivative of decaborane represented by C _{2 B} 10 _{H 12.} A particularly preferable form of the carborane-based aggregation-induced luminescent molecule is a derivative of o-carborane represented by the following general formula (2). In the derivative of o-carborane, the cluster portion where π electrons are delocalized has high electron attraction. It is generally known that a carborane derivative in which a π-electron conjugated unit is introduced into carbon at the 1-position or 2-position emits strong fluorescence (K. Kokado, et al., Macromolecules, 2009, 42, 1418-1420). Etc.).

[However, in the general formula (2), R ₅ and R ₆ independently represent a hydrogen atom, an organic group, or an organometallic group, _{and at least one of R 5} and R ₆ is a π-electron conjugated unit. Represents. ] In the general formula (2), the white circles represent carbon atoms, and the black circles represent boron atoms to which hydrogen atoms are bonded. Carborane represented by the general formula (2) is a cluster molecule having a regular icosahedron structure, and the boron atom and the hydrogen atom located on the back side are not shown in the formula.

Examples of the organic group for substituting the carbolane include a saturated aliphatic hydrocarbon group such as an alkyl group and a cycloalkyl group, and an unsaturated aliphatic hydrocarbon group such as an alkenyl group, an alkynyl group, a cycloalkenyl group and a cycloalkynyl group. , Aromatic hydrocarbon group, heterocyclic group and the like. Specific examples of these organic groups include groups similar to the substituents that substitute for the benzoflo-oxazolo-carbazole derivative described above.

Examples of the organometallic group substituting the carborane include an organometallic group in which metal atoms such as Ir, Pt, Rh, Ru, Ag, Cu, Os, and Re are coordinated. Specific examples of these organic groups include a pyridine ring, a pyridazine ring, a pyrimidine ring, an imidazole ring, a benzimidazole ring, a pyrazole ring, a pyrazine ring, a triazole ring, a benzoxazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, and an indazole. Rings, quinoxaline rings, phenanthridine rings and the like can be mentioned.

Carborane has other substituents such as a sulfonic acid group, a carboxyl group, a phosphoric acid group, a phosphite group, a hydroxyl group, an amino group, an isocyanate group, a silyl group and a halogen atom, like the above-mentioned benzoflo-oxazolo-carbazole derivative. , An organic group such as a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group substituted on the cluster portion, or an organic metal group may be used.

In the general formula (2), R ₅ and R ₆ may have the same structure or different structures as long as at least one of them is a π-electron conjugated unit. Further, R ₅ and R ₆ may be condensed with each other to form a ring. Further, R ₅ and R ₆ may be composed of a combination of an electron-donating π-electron conjugated unit and an electron-accepting π-electron conjugated unit, or an electron-donating π-electron conjugated unit and a non-conjugated atom. It may be composed in combination with a group.

The π-electron conjugated unit includes, for example, an atomic group composed of an organic group such as an aromatic hydrocarbon group or an aromatic heterocyclic group, an organic metal group, or a linking group such as a conjugated diene group, an ethynylene group, or a hetero atom. Or a molecular chain. The π-electron conjugated unit is preferably composed of a planar molecular chain or atomic group in that the molecular motion of the π-electron conjugated unit is easily constrained by the aggregation of carborane.

A particularly preferable form of the π-electron conjugated unit is an aromatic hydrocarbon group or an aromatic because the molecular motion is easily restricted by the aggregation of carborane, and the energy level can be controlled and the molecular motion can be appropriately controlled. It is a heterocyclic group. As the aromatic hydrocarbon group constituting the π-electron conjugated unit, a phenyl group, a naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group and the like are preferable. Examples of the aromatic heterocyclic group constituting the π-electron conjugated unit include a pyridyl group, a pyrimidyl group, a pyrrolyl group, an imidazolyl group, a pyrazolyl group, a triazolyl group, an oxazolyl group, a thiazolyl group, a thiadiazolyl group, an oxadiazolyl group and a triazinyl group. Is preferable. Specifically, as R ₅ and R ₆ , a 9-carbazolylphenyl group, a γ-carbonylylphenyl group, a triphenylsilyl group and the like can also be preferably used.

(Tetraphenylethylene-based aggregation-induced luminescent molecule)
As the tetraphenylethylene-based aggregation-induced luminescent molecule, a tetraphenylethylene derivative having a tetraphenylethylene skeleton represented by the following general formula (3) can be used.

[However, in the general formula (3), R ₇ , R ₈ , R ₉ and R ₁₀ independently represent an organic group or an organometallic group, and o, p, q and r are independent of each other. Then, it represents an integer of 0 to 5. ]

Examples of the organic group that replaces the tetraphenylethylene derivative include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a heterocyclic group. Specific examples of these organic groups include groups similar to the substituents that substitute for the benzoflo-oxazolo-carbazole derivative described above.

Examples of the organometallic group substituting the tetraphenylethylene derivative include an organometallic group in which metal atoms such as Ir, Pt, Rh, Ru, Ag, Cu, Os, and Re are coordinated. Specific examples of these organic groups include groups similar to the above-mentioned organometallic groups that replace carborane.

Like the benzoflo-oxazolo-carbazole derivative, the tetraphenylethylene derivative includes a sulfonic acid group, a carboxyl group, a phosphoric acid group, a phosphite group, a hydroxyl group, an amino group, an isocyanate group, a silyl group, a halogen atom and the like, and other components. The substituent may be present in the tetraphenylethylene skeleton itself, an organic group such as an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a heterocyclic group substituted on the skeleton, or an organic metal group.

In the general formula (3), R _{7 to} R ₁₀ may have the same structure or different structures from one or more of the substituents substituted on the same ring. .. Further, R _{7 to} R ₁₀ may have the same structure or different structures from each other. Further, R _{7 to} R ₁₀ may be fused with substituents substituted on the same ring to form a ring, or condensed with substituents substituted on different rings to form a ring. It may be formed. The tetraphenylethylene derivative contains two or more tetraphenylethylene skeletons represented by the general formula (3), and these plurality of skeletons are connected to each other via any one of _{R 7 to} R _10. You may.

Specific examples of the tetraphenylethylene-based aggregation-induced luminescent molecule include a 9-carbazolylphenyl group and γ at the para-position of the benzene ring of tetraphenylethylene or the tetraphenylethylene derivative represented by the general formula (3). Examples thereof include derivatives in which the −carbonylylphenyl group, 4,6-diphenyl-1,3,5-triazinyl group and the like are substituted, but the present invention is not limited thereto.

(Siror-based aggregation-induced luminescent molecule)
As the siror-based aggregation-induced luminescent molecule, a siror derivative in which a π-electron conjugated unit is bonded to a siror ring can be used. A particularly preferable form of the siror-based aggregation-induced luminescent molecule is a derivative in which the carbons at the 3- and 4-positions of the siror ring represented by the following general formula (4) are substituted with a benzene ring which may have a substituent. Is.

[However, in the general formula (4), R ₁₁ and R ₁₂ each independently represent a hydrocarbon group having 1 to 12 carbon atoms, and s and t are independently integers of 0 to 5. R ₁₃ and R ₁₆ each independently represent an organic group, and R ₁₄ and R ₁₅ each independently represent an organic group having 1 to 20 carbon atoms. ]

_{Examples of R 11} and R ₁₂ that replace the silol derivative include saturated aliphatic hydrocarbon groups having 1 to 12 carbon atoms, unsaturated aliphatic hydrocarbon groups having 1 to 12 carbon atoms, and 1 carbon number. Included are ~ 12 aromatic hydrocarbon groups. Specific examples of these organic groups include groups similar to the substituents that substitute for the benzoflo-oxazolo-carbazole derivative described above. As R ₁₁ and R ₁₂ , hydrocarbon groups having 1 to 6 carbon atoms are more preferable, and hydrocarbon groups having 1 to 4 carbon atoms are further preferable. Further, s and t are preferably 0 or 1, and it is particularly preferable that _{s and t are 0, that is, R 11} and R _{12 are phenyl groups.}

_{Examples of R 13} and R ₁₆ that replace the silol derivative include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an atomic group or a molecular chain composed of a heterocyclic group. Specific examples of these organic groups include groups similar to the above-mentioned substituents that substitute for carborane. R ₁₃ and R ₁₆ are one of a benzene ring, a naphthalene ring, a pyridine ring, a pyrrole ring, an imidazole ring, an imidazoline ring, a pyrazolyl ring, a pyrazine ring, an oxazole ring, a thiazole ring, a furan ring, and a thiophene ring. The π-electron conjugated unit composed of the above is more preferable, a π-electron conjugated unit containing one or more benzene rings is more preferable, and a phenyl group is particularly preferable.

_{Examples of R 14} and R ₁₅ for substituting the silol derivative include a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, an unsaturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, and 1 carbon number. Included are ~ 20 aromatic hydrocarbon groups. Specific examples of these organic groups include groups similar to the substituents that substitute for the benzoflo-oxazolo-carbazole derivative described above. The _{organic group represented by R 14} and R ₁₅ is not limited to hydrocarbons, and may have heteroatoms such as N, O, S, and Si. As R ₁₄ and R ₁₅ , an organic group having 1 to 12 carbon atoms is more preferable, and a phenyl group or an alkyl group having 1 to 12 carbon atoms is further preferable.

(How to obtain AIE molecule)
The above AIE molecule can be synthesized by using a conventionally known method. For example, K.K. Kokado, et al. , Macromolecules, 2009, 42, 1418-1420, U.S. Patent Application Publication No. 2012/299474, U.S. Patent Application Publication No. 2013/177991, U.S. Patent Application Publication No. 2013/89889, Qin W. , Et al. , Chem. Commun. , 2015, 51, 7321-7324, Kim J. et al. Y. , Et al. , Adv. Mater. 2013, 25, 2666-2671, Chen B. , Et al. , Chem. Euro. J. , 2014, 20, 1931-1939. Examples of the rhodamine-based aggregation-induced luminescent molecule include S. cerevisiae. Kamino, et al. , Chem. Commun. , 2010, 46, 9013-9015 can be used.

(Aggregation-induced luminescence of AIE molecules)
FIG. 1 is a conceptual diagram illustrating the aggregation-induced luminescence of AIE molecules. As shown in FIG. 1, the conventional fluorescent luminescent compound which does not exhibit aggregation-induced luminescence causes quenching and the luminescence intensity decreases as the concentration increases. On the other hand, the AIE molecule has a property that the emission intensity increases as the concentration increases. Whether or not the luminescent compound has such aggregation-induced luminescence can be confirmed by dispersing the molecules in the solvent and comparing the luminescence intensity observed for each concentration.

Specifically, a luminescent compound having a predetermined concentration is dispersed in a good solvent at room temperature (25 ° C.), the emission spectrum of the excited luminescent compound is measured, and the peak intensity at the maximum emission wavelength is determined in the case of a dilute dispersion solution. By determining the relative intensity with respect to the above, it is possible to confirm whether or not the substance has aggregation-induced luminescence. As shown in FIG. 1, the emission intensity of the maximum emission wavelength λmax detected from the dispersion solution having a concentration of 0.01 _{mM is I 0} , and the emission intensity of the maximum emission wavelength λmax detected from the dispersion solution having a concentration of 10 mM is I ₁₀ . Then, a luminescent compound satisfying the following mathematical formula (A) is defined as an AIE molecule.
I ₁₀ / I ₀ > 1 ... (A)

(Concentration of AIE molecule)
The AIE molecule may be contained in the light emitting layer at an appropriate concentration as long as it is used in combination with the RISC compound described later. The concentration of the AIE molecule in the light emitting layer in the film can be, for example, 0.1% by mass or more and 99.9% by mass or less. If the charge transportability of the AIE molecule is good, high luminous efficiency can be obtained even if the light emitting layer is formed at such a wide range of concentrations in the film. The light emitting layer can be composed of only the AIE molecule and the RISC compound, or can be composed of the AIE molecule, the RISC compound, the host compound described later, and other luminescent dopants.

The concentration of the AIE molecule in the light emitting layer in the film is preferably 2% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more. When the concentration of AIE molecules in the film is 2% by mass or more, strong luminescence due to aggregation of AIE molecules is easily obtained, and when it is 10% by mass or more, the luminescent compound is more luminescent as compared with a general light emitting layer. Since it exists in an agglomerated state, light emission by the agglomerated AIE molecules can be surely obtained, and deterioration of the luminescent compound due to oxygen, moisture, etc. in the atmosphere can be avoided. The concentration of the AIE molecule in the light emitting layer in the film may be 70% by mass or less, or 70% by mass or more and 99.9% by mass or less. When the concentration of the AIE molecule in the film is 70% by mass or less, high luminous efficiency can be obtained when a host compound or the like is used in combination with the RISC compound.

<RISC compound>
As the RISC compound, the above-mentioned AIE molecule is a compound in which the energy difference (ΔE _st ) between the lowest excited singlet energy level (S ₁ ) and the lowest excited triplet energy level (T _{1) is 0.5 eV or less.} Can be used in combination with. Delta] E _st of RISC compound, preferably 0.3eV or less, and more preferably not more than 0.1 eV. Since the RISC compound _{has a small ΔE st} , it has a property of causing an intersystem crossing from a triplet exciton to a singlet exciton, which is spin-forbidden, with a high probability even at room temperature.

In general, under electric field excitation, triplet excitons are theoretically generated at a rate of 75%. However, in the conventional fluorescent compound, since the triplet excitons generated are easily deradiated without radiation, theoretically, only a maximum emission quantum yield of 25% can be realized. On the other hand, _{when a RISC compound having a small ΔE st} is used, triplet excitons generated by electric field excitation can be inverted into singlet excitons by intersystem crossing. Since singlet excitons can generate an instantaneous radiation transition and can generate a radiation transition after intermolecular energy transfer, the internal quantum efficiency can be improved by using a RISC compound in the light emitting layer.

The RISC compound may emit delayed emission by the radiation transition of the singlet exciton, or may transfer energy to the AIE molecule in which the singlet exciton is used in combination to cause the AIE molecule to emit light. When the AIE molecule to be used is made to emit light, the rate of intermolecular energy transfer _{is preferably sufficiently faster than the rate of ISC and the rate of radiation transition and non-radiation transition from T 1} , and fluorescence resonance energy transfer (FRET). From the viewpoint of efficiency, it is preferable to use a combination in which the absorption spectrum of the RISC compound and the absorption spectrum of the AIE molecule have a large overlapping integral.

As the RISC compound, a Π-conjugated compound represented by the following general formula (A) is particularly preferably used. According to the Π conjugated system compound represented by the general formula (A), the highest occupied molecular orbital (HOMO) and the lowest empty orbital (LOWEST Unoccuped Molecular Orbital: LUMO) in the molecule are spatially separated. Since the overlap of the wave functions of each other _{is small, it is possible to obtain a compound in which ΔEst} is sufficiently small and RISC is likely to occur at room temperature.

[However, in the general formula (A), A represents an electron acceptor site, D represents an electron donor site, L represents a divalent linking group, and l and m are independent of each other. , Represents an integer of 1-4. ]

As the acceptor site A, an atomic group or a molecular chain having high electron attractability and a deep energy level of LUMO or HOMO in the molecule can be used. As the acceptor site A, an atomic group or a molecular chain having aromaticity based on Hückel's law is preferable, and an atomic group or a molecular chain containing an aromatic heterocycle having a nitrogen atom is more preferable. Specific examples of the acceptor site A include a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a sarin ring, a phthalazine ring, a pteridine ring, a phenanthridine ring, a phenanthroline ring, and a condensed ring containing these ring structures. .. These acceptor sites A may have substituents.

As the donor site D, an atomic group or a molecular chain having a high electron donating property and a shallow energy level of LUMO or HOMO in the molecule can be used. Specific examples of the donor site D include an aryl group substituted with an electron-donating group (benzene ring, inden ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, acenaphthylene ring, biphenylene ring, naphthacene ring, etc. Pyrene ring, pentalene ring, acetylene ring, heptalene ring, triphenylene ring, as-indacene ring, chrysen ring, s-indacene ring, pleiaden ring, phenanthrene ring, fluorantene ring, perylene ring, acephenanthrene ring, biphenyl Rings, terphenyl rings, tetraphenyl rings, etc.) and electron-donating heterocyclic groups that may be substituted (pyrrole ring, indole ring, carbazole ring, indroindole ring, 9,10-dihydroacrine ring, phenanthrene ring, etc.) Saddin ring, phenanthidine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, aza A carbazole ring, a diazacarbazole ring, etc.), an amino group that may be substituted, or an alkyl group. Above all, since it has a high electron donating property, it is preferably an electron donating heterocyclic group which may be substituted.

As the linking group L, either a structure that extends the Π-conjugated system formed by each site or a structure that blocks the Π-conjugated system formed by each site can be used. Further, it may be a rigid structure in which the change in the molecular structure is small between the ground state and each excited state, or it may be a structure having a high degree of freedom that can suppress the reverse charge transfer from the intramolecular charge transfer state. Good. Specific examples of the linking group L include a divalent or higher valent group composed of a hydrocarbon group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like. These linking groups L may have a substituent.

Examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, etc.). Cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aromatic hydrocarbon group (aromatic hydrocarbon) Also referred to as a ring group, an aromatic carbocyclic group, an aryl group, etc., for example, a phenyl group, a p-chlorophenyl group, a mesityl group, a trill group, a xylyl group, a naphthyl group, an anthryl group, an azulenyl group, an acenaphthenyl group, a fluorenyl group, a phenanthryl group. Group, indenyl group, pyrenyl group, biphenylyl group, etc.), aromatic heterocyclic group (eg, pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (eg, pyridyl group, pyramidinyl group, biphenylyl group, etc.) 1,2,4-triazole-1-yl group, 1,2,3-triazole-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isooxazolyl group, isothiazolyl group, frazayl group, thienyl Group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carbolin ring of the carbolinyl group is nitrogen. Atomatically replaced), quinoxalinyl group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholic group, oxazolidyl group, etc.), alkoxy group (eg, , Methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.) , Phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.) Groups, etc.), arylthio groups (eg, phenylthio groups, naphthylthio groups, etc.), alkoxykas Lubonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.) , Sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, Naftylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (eg, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group , Phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (eg, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.) , Amid groups (eg, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonyl Amino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octyl Aminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methyl ureido group, ethyl ureido group, pentyl ureido group) , Cyclohexyl ureido group, octyl ureido group, dodecyl ureido group, phenyl ureido group, naphthyl ureido group, 2-pyridyl amino ureido group, etc.), sulfinyl group (for example, methi) Rusulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl) Group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group) Etc.), Amino group (eg, amino group, ethylamino group, dimethylamino group, diphenylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2- Pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), Examples thereof include a cyano group, a nitro group, a hydroxy group, a mercapto group, a silyl group (for example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, a phenyldiethylsilyl group, etc.), a phosphono group and the like.

Among these, the substituents substituting the Π-conjugated compound represented by the general formula (A) include an alkyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, an alkoxy group, an amino group, or a cyano group. Is preferable. Preferred specific examples of the aromatic hydrocarbon group and the aromatic heterocyclic group include an indole ring, an indole ring, a benzothiazole ring, a benzoxazole ring, a benzimidazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxalin ring, and an isoindol. Examples thereof include a ring, a naphthylidine ring, a phthalazine ring, a carbazole ring, a carboline ring, a diazacarbazole ring, an aclysine ring, a phenanthridine ring, a phenanthroline ring, a phenazine ring, an azadibenzofuran ring, and an azadibenzothiophene ring. These substituents can also be used as acceptor sites.

As the RISC compound, a compound having a benzene ring as the linking group L can be preferably used. It is preferable that the acceptor site A and the donor site D are bonded to each other at the para position with respect to the linking group L composed of the benzene ring. Further, it is preferable that one or more of the ortho positions of the bond positions to which the acceptor site A is bonded are hydrogen atoms. Further, it is preferable that one or more of the ortho positions of the bonding positions to which the donor site D binds are electron-donating groups. Specific examples of such RISC compounds include compounds A-1 to A-64 described in JP-A-2017-075121.

<Minimization design of ΔEst>
In order to reduce the ΔEst of the compound represented by the general formula (A), it is most effective to reduce the spatial overlap between the highest occupied orbital (HOMO) and the lowest empty orbital (LUMO) in the molecule. .. In general, it is known that among the electron orbitals of a molecule, HOMO is distributed in an electron donating site and LUMO is distributed in an electron attracting site. Therefore, for example, as described in Applied Physics Vol. 82, No. 6, 2013 of "Organic Optoelectronics Reaching the Practical Use Stage", an electron-donating skeleton and electron-attracting property in a molecule. By introducing the skeleton of HOMO, the site where HOMO is localized and the site where LUMO is localized can be separated.

Further, in order to reduce ΔEst, it is also effective to reduce the change in the molecular structure between the ground state and the excited state of the compound. As a method of reducing the change in the molecular structure, for example, there is a method of making the compound rigid. For example, a method of suppressing the free rotation of the bond between the rings, a method of introducing a condensed ring having a large π-conjugated surface, or a method of reducing the number of freely movable parts in the molecule can be used. In particular, by making the site involved in light emission rigid in the compound, it is possible to reduce the structural change in the excited state.

<Electronic density distribution>
The distribution state of HOMO and LUMO in the compound can be obtained from the electron density distribution when the structure is optimized obtained by the calculation of the molecular orbital. The molecular orbital calculation can be performed using the molecular orbital calculation software using B3LYP as a functional and 6-31G (d) as a basis function. The type of software for calculating the molecular orbital is not particularly limited. As the software for calculating the molecular orbital, for example, Gaussian 09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010) manufactured by Gaussian, USA can be used.

Also, Delta] E _st compounds after structural optimization by molecular orbital calculation, time-dependent density functional theory (DFT: Time-Dependent) to perform the calculations of the excited state energy by energy level of _{S 1} (E (S ₁ )) and the energy level of _{T 1 (E (T 1} )) can be obtained and _{calculated as ΔE st} = | E (S ₁ ) -E (T ₁ ) |. The smaller the calculated ΔE _{st, the} more separated the HOMO and LUMO.

<Lowest excited singlet energy level S ₁ >
The energy (E (S ₁ )) of the lowest excited singlet energy level (S ₁ ) can be determined based on a known method as shown below. First, a compound to be measured is vapor-deposited on a quartz substrate to prepare a sample, and the absorption spectrum (vertical axis: absorbance, horizontal axis: wavelength) of the sample is measured at room temperature (300 K). After that, a tangent line is drawn with respect to the rising edge of the obtained absorption spectrum on the long wavelength side, and the calculation can be performed using a predetermined conversion formula based on the wavelength value at the intersection of the tangent line and the horizontal axis.

However, when the cohesiveness of the compound to be measured is relatively high, an error due to cohesion may occur in the measurement of the thin film. The peak value of the maximum emission wavelength measured in a solution state at room temperature (25 ° C.) is used as an approximate value, provided that the Stokes shift of the compound is relatively small and the molecular structure change between the ground state and the excited state is small. be able to. As the solvent, a solvent having a small solvent effect and not significantly affecting the aggregated state of the compound, for example, a non-polar solvent such as cyclohexane or toluene can be used.

<Minimum excited triplet energy level T ₁ >
The energy (E (T ₁ )) of the lowest excited triplet energy level (T ₁ ) can be determined based on the photoluminescence (PL) properties of the thin film or solution, as shown below. For example, after thinning a diluted dispersion of the compound to be measured into a thin film, the transient PL characteristics are measured using a streak camera to separate the fluorescence component and the phosphorescence component. Then, the absolute value of the obtained energy difference is defined as ΔE _st, and it can be calculated from _{ΔE st and S 1} obtained in advance. For PL characteristics, for example, the compound is excited by laser light, the internal quantum efficiency is measured by an absolute PL quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics), and the emission lifetime is measured by a streak camera C4334 (manufactured by Hamamatsu Photonics). Can be measured.

(Concentration of RISC compound)
The RISC compound may be contained in the light emitting layer at an appropriate concentration as long as it is used in combination with the AIE molecule. The concentration of the RISC compound in the light emitting layer is, for example, 0.1% by mass or more and 50% by mass or less, preferably 1% by mass or more and 30% by mass or less, and more preferably 5% by mass or more and 30% by mass or less. Can be done. When the concentration of the RISC compound in the film is 1% by mass or more, the luminous efficiency can be significantly improved by using the triplet excitons for light emission. Further, when the concentration of the RISC compound in the film is 30% by mass or less, the light emission from the AIE molecule, which is unlikely to cause concentration quenching, can be efficiently used.

<< Constituent layer of organic EL element >>
The organic EL device according to the present invention can be provided, for example, as a structure having an anode and a cathode on a base material and an organic constituent layer including a light emitting layer sandwiched between the anode and the cathode. Typical element configurations of the organic EL device according to the present invention include, but are not limited to, the following configurations.
(1) anode / light emitting layer / cathode (2) anode / light emitting layer / electron transport layer / cathode (3) anode / hole transport layer / light emitting layer / cathode (4) anode / hole transport layer / light emitting layer / electron Transport layer / cathode (5) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (6) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / cathode (6) 7) Anotopium / hole injection layer / hole transport layer / (electron blocking layer /) light emitting layer / (hole blocking layer /) electron transport layer / electron injection layer / cathode

The organic EL element according to the present invention may be provided on the outside of the electrode by appropriately combining layers such as a sealing layer, a barrier layer, and a light extraction layer. In the above configuration, the layer excluding the anode and the cathode is also referred to as an "organic layer".

The light emitting layer may be composed of a single layer or a plurality of layers. When the light emitting layer is composed of a plurality of layers, a non-light emitting intermediate layer may be provided between the light emitting layers. Further, if necessary, a hole blocking layer (also referred to as a hole barrier layer) or an electron injection layer (also referred to as a cathode buffer layer) may be provided between the light emitting layer and the cathode. Further, an electron blocking layer (also referred to as an electron barrier layer) or a hole injection layer (also referred to as an anode buffer layer) may be provided between the light emitting layer and the anode.

(Tandem structure)
The organic EL element according to the present invention may be an element having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are laminated. Typical element configurations of the tandem structure include, for example, the following configurations.
(I) Anode / 1st light emitting unit / 2nd light emitting unit / 3rd light emitting unit / cathode (II) Anode / 1st light emitting unit / intermediate layer / 2nd light emitting unit / intermediate layer / 3rd light emitting unit / cathode

In the tandem type organic EL element, the plurality of light emitting units may all have the same configuration or may have different configurations. Further, some light emitting units may have the same configuration, and the remaining light emitting units may have different configurations. Further, the tandem type organic EL element may be composed of two light emitting units, or may be composed of four or more light emitting units by providing a light emitting unit or an intermediate layer between the third light emitting unit and the cathode. You may. The light emitting units may be laminated adjacent to each other, or may be laminated via an intermediate layer.

The intermediate layer is also generally called an intermediate electrode, an intermediate conductive layer, a charge generation layer, an electron extraction layer, a connection layer, or an intermediate insulation layer, and electrons are transferred to a layer adjacent to the anode side to a layer adjacent to the cathode side. Any layer having a function of supplying holes can be provided with a known material and composition.

Examples of the material of the intermediate layer include ITO (inorganic / tin oxide), IZO ( _{inorganic / zinc oxide), ZnO 2} , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, CuAlO ₂ , and CuGaO. ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO ₂ , Al and other conductive inorganic compound layers, Au / Bi ₂ O _{3 and} other bilayer films, SnO ₂ / Ag / SnO ₂ , ZnO / Ag / ZnO, Bi ₂ and _{O 3 / Au / Bi 2 O} 3, TiO 2 / TiN / TiO 2, TiO 2 / ZrN / TiO 2 or the like multilayer _film, fullerenes such as _{C 60,} or a conductive organic material layer such as oligothiophene, Examples thereof include, but are not limited to, conductive organic compound layers such as metallic phthalocyanines, metal-free phthalocyanines, metal porphyrins, and metal-free porphyrins.

A preferable configuration of the light emitting unit includes, for example, a configuration in which the anode and the cathode are excluded from the element configuration according to any one of (1) to (7) above, but the configuration is not limited thereto.

Specific examples of the tandem type organic EL element include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, and US Pat. No. 6,872. , 472, US Patent No. 6,107,734, US Patent No. 6,337,492, International Publication No. 2005/009087, Japanese Patent Application Laid-Open No. 2006-228712, Japanese Patent Application Laid-Open No. 2006-24791, Japanese Patent Application Laid-Open No. 2006- 49393, Japanese Patent Application Laid-Open No. 2006-49394, Japanese Patent Application Laid-Open No. 2006-49396, Japanese Patent Application Laid-Open No. 2011-96679, Japanese Patent Application Laid-Open No. 2005-340187, Japanese Patent No. 4711424, Japanese Patent No. 3496681, Patent No. 38845664, Japanese Patent No. 4213169. , Japanese Patent Application Laid-Open No. 2010-192719, Japanese Patent Application Laid-Open No. 2009-0762929, Japanese Patent Application Laid-Open No. 2008-0784414, Japanese Patent Application Laid-Open No. 2007-059848, Japanese Patent Application Laid-Open No. 2003-272860, Japanese Patent Application Laid-Open No. 2003-045676, International Publication No. 2005/094130. Etc., but the element configuration and constituent materials are not limited thereto.

In the organic EL device according to the present invention, the AIE molecule and the RISC compound may be contained in a light emitting layer composed of a single layer or composed of a plurality of layers as long as they are used in combination in the same light emitting layer. It may be contained in one or more of the light emitting layers. Further, as long as the AIE molecule and the RISC compound are used in combination in the same light emitting layer, they may be contained in a single light emitting unit among the light emitting units constituting the tandem type, or may be included in a plurality of light emitting units. May be included.

The organic EL device according to the present invention has either a configuration in which only light emitted from an AIE molecule is emitted or a configuration in which both light emitted from an AIE molecule and light emitted from a RISC compound are emitted. May be. The relationship between the energy level of the AIE molecule and the energy level of the RISC compound is not particularly limited. However, when a host compound is used in the light emitting layer, it is preferable that the lowest excited triplet energy level of the RISC compound is deeper than the lowest excited triplet energy level of the host compound.

The organic EL device according to the present invention preferably has an external extraction quantum efficiency of light emission at room temperature (25 ° C.) of 1% or more, and more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons passed through the organic EL element × 100.

Hereinafter, each layer (hole injection layer, hole transport layer, hole blocking layer, electron blocking layer, electron transport layer, electron injection layer, light emitting layer) constituting the organic EL device according to the present invention will be described.

《Hole injection layer》
The hole injection layer is a layer provided between the anode and the light emitting layer in order to reduce the driving voltage and improve the emission brightness. For the hole injection layer, refer to Volume 2, Chapter 2, "Electrode Materials" (pages 123-166) of "Organic EL Devices and Their Industrial Frontiers (November 30, 1998, published by NTS)". It is described in detail. The hole injection layer can be provided as needed. The hole injection layer may be provided, for example, between the anode and the light emitting layer or between the anode and the hole transport layer.

The details of the hole injection layer are also described in JP-A-9-45479, JP-A-9-2660062, JP-A-8-288609, and the like.

As the material of the hole injection layer, for example, the same material as the material of the hole transport layer described later can be used. As the material of the hole injection layer, one type may be used alone, or a plurality of types may be used in combination.

Examples of the material of the hole injection layer include phthalocyanine derivatives typified by copper phthalocyanine, hexaazatriphenylene derivatives as described in JP-A-2003-591432 and JP-A-2006-135145, and vanadium oxide. Metal oxides, amorphous carbon, conductive polymers such as polyaniline (emeraldine) and polythiophene, orthometallated complexes typified by tris (2-phenylpyridine) iridium complexes, triarylamine derivatives and the like are preferable.

《Hole transport layer》
The hole transport layer may be made of a material having a function of transporting holes, and may have a function of transmitting holes injected from the anode to the light emitting layer.

The total thickness of the hole transport layer is not particularly limited, but is usually 5 nm to 5 μm, preferably 2 to 500 nm, and more preferably 5 to 200 nm.

As the material of the hole transport layer, it suffices to have any of hole injection property, hole transport property, and electron barrier property, and a known compound having such properties is used. Can be done. As the material of the hole transport layer, one type may be used alone, or a plurality of types may be used in combination.

Examples of the material of the hole transport layer include porphyrin derivative, phthalocyanine derivative, oxazole derivative, oxaziazole derivative, triazole derivative, imidazole derivative, pyrazoline derivative, pyrazolone derivative, phenylenediamine derivative, hydrazone derivative, stillben derivative, and polyarylalkane. A polymer in which a derivative, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an isoindole derivative, an acene derivative such as anthracene or naphthalene, a fluorene derivative, a fluorenone derivative, polyvinylcarbazole, or an aromatic amine is introduced into a main chain or a side chain. Examples thereof include polymers or oligomers, polysilanes, conductive polymers or oligomers (eg, PEDOT: PSS, aniline-based copolymers, polyaniline, polythiophene, etc.).

Examples of the triarylamine derivative include a benzidine type represented by α-NPD, a starburst type represented by MTDATA, and a compound having fluorene or anthracene in the connecting core portion of the triarylamine.

Further, as the material of the hole transport layer, a hexaazatriphenylene derivative as described in JP-A-2003-591432, JP-A-2006-135145 and the like can also be used.

Further, as the material of the hole transport layer, JP-A-11-251067, J. Hung, et. al. Inorganic semiconductors such as p-type-Si and p-type-SiC as described in the authored literature (Applied Physics Letters, 80 (2002), p.139) can also be used. Further, an orthometalated organometallic complex having Ir or Pt in the central metal represented by Ir (ppy) _{3 is also preferably used.}

The hole transport layer may be formed as a layer having a high p property by doping with a doping material. Specific examples of the hole transport layer having such a structure include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J. Mol. Apple. Phys. , 95, 5773 (2004) and the like.

As the material of the hole transport layer, a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organic metal complex, a polymer or an oligomer in which an aromatic amine is introduced into the main chain or a side chain, or the like is preferably used. ..

Specific examples of the material of the hole transport layer include, but are not limited to, the compounds described in the following documents. Apple. Phys. Lett. , 69, 2160 (1996), J. Mol. Lumin. , 72-74, 985 (1997), Appl. Phys. Lett. , 78, 673 (2001), Appl. Phys. Lett. , 90, 183503 (2007), Appl. Phys. Lett. , 90, 183503 (2007), Appl. Phys. Lett. , 51, 913 (1987), Synth. Met. , 87, 171 (1997), Synth. Met. , 91, 209 (1997), Synth. Met. , 111,421 (2000), SID Symposium Digital, 37,923 (2006), J. Mol. Mater. Chern. , 3,319 (1993), Adv. Mater. , 6,677 (1994), Chern. Mater. , 15, 3148 (2003), U.S. Patent Publication No. 20130162053, U.S. Patent Publication No. 20020158222, U.S. Patent Publication No. 20060240279, U.S. Patent Publication No. 20080220265, U.S. Patent No. 5061569, International Publication No. 2007002683, International Publication 2009018009, EP650955, US Patent Publication No. 20080124572, US Patent Publication No. 20070278938, US Patent Publication No. 20080106190, US Patent Publication No. 20080018221, International Publication No. 20121115034, Japanese Patent Publication No. 2003-591432, Special Publication No. 2003-591432 Kai 2006-135145, US Patent Application No. 13/585981, and the like.

《Hole blocking layer》
The hole blocking layer is a layer having a function of an electron transporting layer in a broad sense, and is preferably made of a material having a function of transporting electrons and a small ability to transport holes. By blocking holes while transporting electrons, the probability of recombination of electrons and holes can be improved. Further, the electron transport layer can also be used as a hole blocking layer, if necessary. The hole blocking layer is preferably provided adjacent to the cathode side of the light emitting layer.

The thickness of the hole blocking layer is not particularly limited, but is preferably 3 to 100 nm, more preferably 5 to 30 nm.

As the material of the hole blocking layer, the material of the electron transport layer described later and the material used as the host compound described later are preferably used.

《Electronic blocking layer》
The electron blocking layer is a layer having a function of a hole transporting layer in a broad sense, and is preferably made of a material having a function of transporting holes but having a small ability to transport electrons. By blocking electrons while transporting holes, the probability of recombination between electrons and holes can be improved. Further, the hole transport layer can also be used as an electron blocking layer, if necessary. The electron blocking layer is preferably provided adjacent to the anode side of the light emitting layer.

The thickness of the electron blocking layer is not particularly limited, but is preferably 3 to 100 nm, more preferably 5 to 30 nm.

As the material of the electron blocking layer, the material of the hole transport layer described later and the material used as the host compound described later are preferably used.

《Electron transport layer》
The electron transport layer may be made of a material having a function of transporting electrons and may have a function of transmitting electrons injected from the cathode to the light emitting layer.

The total thickness of the electron transport layer is not particularly limited, but is usually 2 nm to 5 μm, preferably 2 to 500 nm, and more preferably 5 to 200 nm.

In the organic EL element, when the light generated in the light emitting layer is taken out from the electrode, the light taken out directly from the light emitting layer and the light taken out after being reflected by the electrode located at the opposite electrode of the electrode that takes out the light interfere with each other. It is known. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total film thickness of the electron transport layer between several nm and several μm. On the other hand, if the thickness of the electron transport layer is increased, the voltage tends to increase. Therefore, especially when the thickness is thick, the electron mobility of the electron transport layer ^{is preferably 10-5} cm ² / Vs or more. ..

As the material of the electron transport layer, it suffices to have any of electron injection property, electron transport property, and hole barrier property, and a known compound having such properties can be used. .. As the material of the electron transport layer, one kind may be used alone, or a plurality of kinds may be used in combination.

Examples of the material of the electron transport layer include a nitrogen-containing aromatic heterocyclic derivative (carbazole derivative, azacarbazole derivative (one or more of carbon atoms constituting the carbazole ring replaced with a nitrogen atom), a pyridine derivative, and pyrimidine. Derivatives, pyrazine derivatives, pyridazine derivatives, triazine derivatives, quinoline derivatives, quinoxalin derivatives, phenanthroline derivatives, azatriphenylene derivatives, oxazole derivatives, thiazole derivatives, oxadiazole derivatives, thiazazole derivatives, triazole derivatives, benzimidazole derivatives, benzoxazole derivatives, benz Examples thereof include thiazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, silol derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.).

Further, as the material of the electron transport layer, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, for example, tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) Aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq) Etc., Examples thereof include metal complexes in which the central metal of these metal complexes is replaced with In, Mg, Cu, Ca, Sn, Ga or Pb.

Examples of the material of the electron transport layer include metal-free or metal phthalocyanine, or those whose terminals are substituted with an alkyl group, a sulfonic acid group, or the like. Further, a distyrylpyrazine derivative that can be used as a material for the light emitting layer can be used, and an inorganic semiconductor such as n-type-Si or n-type-SiC can also be used. Further, a polymer material in which these materials are introduced into a polymer chain, or a polymer material in which these materials are used as a polymer main chain can also be used.

The electron transport layer may be formed as a layer having a high n property by doping with a doping material. Examples of the doping material include n-type dopants such as metal complexes and metal compounds such as metal halides. Specific examples of the electron transport layer having such a structure include JP-A-4-2970776, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175, J. Mol. Apple. Phys. , 95, 5773 (2004) and the like.

Specific examples of the material of the electron transport layer include, but are not limited to, the compounds described in the following documents. U.S. Patent No. 6528187, U.S. Patent No. 7230107, U.S. Patent Publication No. 20050025993, U.S. Patent Publication No. 20040036077, U.S. Patent Publication No. 200901315316, U.S. Patent Publication No. 20090101870, U.S. Patent Publication No. 20090179554, International Publication No. 200360956, International Publication No. 2008132055, Appl. Phys. Lett. , 75, 4 (1999), Appl. Phys. Lett. , 79,449 (2001), Appl. Phys. Lett. , 81, 162 (2002), Appl. Phys. Lett. , 81, 162 (2002), Appl. Phys. Lett. , 79,156 (2001), U.S. Patent No. 7964293, U.S. Patent Publication No. 2009030202, International Publication No. 2004080975, International Publication No. 200463159, International Publication No. 2005085387, International Publication No. 2006067931, International Publication No. 2007086552 , International Publication No. 2008114690, International Publication No. 2009069442, International Publication No. 2009066779, International Publication No. 2009054253, International Publication No. 2011086935, International Publication No. 2010150593, International Publication No. 20100047707, EP23111826, Japanese Patent Application Laid-Open No. 2010- 251675, 2009-209133, 2009-124114, 2008-277810, 2006-156445, 2005-340122, 2003-45662. Japanese Patent Application Laid-Open No. 2003-31367, Japanese Patent Application Laid-Open No. 2003-282270, International Publication No. 20121115034, and the like.

More preferable materials for the electron transport layer include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives.

《Electron injection layer》
The electron injection layer is a layer provided between the cathode and the light emitting layer in order to reduce the driving voltage and improve the emission brightness. The details of the electron injection layer can be found in Volume 2, Chapter 2, "Electrode Materials" (pages 123-166) of "Organic EL Devices and Their Industrial Frontiers (November 30, 1998, published by NTS)". It is described in. The electron injection layer can be provided as needed. The electron injection layer may be provided, for example, between the cathode and the light emitting layer or between the cathode and the electron transport layer.

The electron injection layer is preferably an extremely thin film. The thickness of the electron injection layer is preferably 0.1 to 5 nm. The electron injection layer may be a non-uniform film in which constituent materials are intermittently present.

The details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586 and the like.

Specific examples of materials preferably used for the electron injection layer include metals such as strontium and aluminum, alkali metal compounds such as lithium fluoride, sodium fluoride and potassium fluoride, magnesium fluoride and calcium fluoride. Examples thereof include alkaline earth metal compounds such as aluminum oxide, metal oxides such as aluminum oxide, and metal complexes such as lithium 8-hydroxyquinolate (Liq). It is also possible to use the same material as the material of the electron transport layer described above. As the material of the electron injection layer, one type may be used alone, or a plurality of types may be used in combination.

《Light emitting layer》
The light emitting layer is a layer that provides a field for generating light. The electrons and holes injected from the electrode or the adjacent layer are recombined in the light emitting layer, and light emission occurs with the deactivation of excitons generated by the recombination. The portion that emits light may be in the layer of the light emitting layer or at the interface between the light emitting layer and the adjacent layer.

The total thickness of the light emitting layer is not particularly limited, but from the viewpoint of improving the homogeneity of the formed film, preventing the application of an unnecessary high voltage during light emission, and with respect to the driving current. From the viewpoint of improving the stability of the emitted color, it is preferably 2 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 to 200 nm.

The individual thickness of the light emitting layer is preferably 2 nm to 1 μm, more preferably 2 to 200 nm, and even more preferably 3 to 150 nm.

The light emitting layer preferably contains a light emitting dopant (a light emitting dopant compound, a dopant compound, also simply referred to as a dopant) and a host compound (a matrix material, a light emitting host compound, also simply referred to as a host). In the organic EL device according to the present embodiment, the AIE molecule functions as a light emitting dopant. Further, the RISC compound is treated as a light emitting dopant regardless of the presence or absence of radiation transition.

(1) Light-emitting dopant Examples of the light-emitting dopant include a fluorescent dopant (also referred to as a fluorescent dopant or a fluorescent compound) and a phosphorescent dopant (also referred to as a phosphorescent dopant or a phosphorescent compound).

The concentration of the light emitting dopant in the light emitting layer can be arbitrarily determined based on the dopant used and the requirements of the device. The light emitting dopant may be distributed at a uniform concentration with respect to the film thickness direction of the light emitting layer, or may be distributed at an arbitrary non-uniform concentration.

As the light emitting dopant, in addition to the above-mentioned AIE molecule and RISC compound, other fluorescent light emitting dopants and phosphorescent light emitting dopants can also be used in combination. One kind of luminescent compound may be used for each fluorescent dopant or each phosphorescent dopant, or a plurality of kinds of luminescent compounds may be used in combination. Further, different light emitting dopants may be used in combination in the same light emitting layer, or different light emitting dopants may be used for different light emitting layers. With such a combination, it is possible to obtain an arbitrary emission color for the emission emitted from the organic EL element.

The emission colors of the organic EL element and the compound according to the present invention are shown in FIG. 4.16 on page 108 of the "New Color Science Handbook" (edited by the Japan Color Society, edited by the University of Tokyo Press, 1985). It can be defined by the color when the result measured by (manufactured by Konica Minolta Sensing Co., Ltd.) is applied to the CIE chromaticity coordinates.

The organic EL device according to the present invention may be an element in which one or more light emitting layers contain a plurality of light emitting dopants having different light emitting colors and exhibit white light emission. The combination of light emitting dopants exhibiting white light emission is not particularly limited, and examples thereof include a combination of blue and orange, a combination of blue, green, and red.

The white light emission exhibited by the organic EL element according to the present invention is not limited in hue and the like, and may be white closer to orange or white closer to blue, but has a 2 degree viewing angle front luminance. When measured by the above method ^{, the chromaticity in the CIE 1931 color system at 1000 cd / m 2} is within the region of x = 0.39 ± 0.09 and y = 0.38 ± 0.08. preferable.

(1.1) Phosphorescent Dopant The phosphorescent dopant according to the present invention is a compound in which light emission from an excited triplet is observed. Specifically, it is defined as a compound that emits phosphorescent light at room temperature (25 ° C.) and has a phosphorescent quantum yield of 0.01 or more at 25 ° C. The preferable phosphorescent quantum yield of the phosphorescent dopant is 0.1 or more.

The phosphorus photon yield can be measured by the method described on page 398 (1992 edition, Maruzen) of Spectroscopy II of the 4th edition Experimental Chemistry Course 7. The phosphorescence quantum yield in a solution can be measured using various solvents, but the phosphorescence dopant according to the present invention achieves a phosphorescence quantum yield of 0.01 or more in any of any solvents. Just do it.

The principle of light emission of a phosphorescent dopant is roughly divided into two types. One is that carrier recombination occurs on the host compound to which the carriers are transported to generate an excited state of the host compound, and this energy is transferred to the phosphorescent dopant to emit light from the phosphorescent dopant. It is an energy transfer type that obtains. The other is a carrier trap type in which the phosphorescent dopant serves as a carrier trap, and carriers recombine on the phosphorescent dopant to obtain light emission from the phosphorescent dopant. In either case, the excited state energy of the phosphorescent dopant is required to be lower than the excited state energy of the host compound.

In the organic EL device according to the present embodiment, as the phosphorescent light emitting dopant, an appropriate type used for the light emitting layer of a general organic EL device can be used. The principle of light emission of the phosphorescent dopant may be based on any of the above principles. However, in the organic EL device according to the present embodiment, if a phosphorescent dopant is used in combination with the RISC compound, the luminous efficiency may be lowered. In such a case, a configuration in which a phosphorescent dopant is not used in combination is more preferable.

Specific examples of the phosphorescent dopant include, but are not limited to, the compounds described in the following documents. Nature, 395, 151 (1998), Appl. Phys. Lett. , 78, 1622 (2001), Adv. Mater. , 19, 739 (2007), Chern. Mater. , 17, 3532 (2005), Adv. Mater. , 17, 1059 (2005), International Publication No. 2009100991, International Publication No. 2008101842, International Publication No. 2003040257, US Patent Publication No. 2006835469, US Patent Publication No. 20060202194, US Patent Publication No. 20070087321, US Patent Publication No. No. 20050244673, Inorg. Chern. , 40, 1704 (2001), Chern. Mater. , 16, 2480 (2004), Adv. Mater. , 16, 2003 (2004), Angew. Chern. lnt. Ed. , 2006, 45, 7800, Appl. Phys. Lett. , 86, 153505 (2005), Chern. Lett. , 34,592 (2005), Chern. Commun. , 2906 (2005), Inorg. Chern. , 42, 1248 (2003), International Publication No. 2009050290, International Publication No. 2002015645, International Publication No. 2009006573, US Patent Publication No. 20020034656, US Pat. No. 73322232, US Patent Publication No. 20090108737, US Patent Publication No. 200900397776, U.S. Patent No. 6921915, U.S. Pat. No. 6687266, U.S. Patent Publication No. 20070190359, U.S. Patent Publication No. 2006008670, U.S. Patent Publication No. 20090165846, U.S. Patent Publication No. 20080015355, U.S. Patent No. 7250226, U.S.A. Patent No. 7396598, U.S. Patent Publication No. 20060263635, U.S. Patent Publication No. 20130138657, U.S. Patent Publication No. 20130152802, U.S. Patent No. 70090928, Angew. Chern. lnt. Ed. , 47, 1 (2008), Chern. Mater. , 18, 5119 (2006), Inorg. Chern. , 46,4308 (2007), Organometallics, 23,3745 (2004), Appl. Phys. Lett. , 74,1361 (1999), International Publication No. 2002002714, International Publication No. 200609024, International Publication No. 2006056418, International Publication No. 20050193773, International Publication No. 2005238373, International Publication No. 2005223873, International Publication No. 2007004380, International Publication No. 2006082742, US Patent Publication No. 20060251923, US Patent Publication No. 20050260441, US Patent No. 73935999, US Patent No. 7534505, US Patent No. 7445855, US Patent Publication No. 20070190359, US Patent Publication No. 20080297033 No., U.S. Patent No. 73338722, U.S. Patent Publication No. 20020134984, U.S. Patent No. 7279704, U.S. Patent Publication No. 2006098120, U.S. Patent Publication No. 2006103874, International Publication No. 2005076380, International Publication No. 20100032663, International Publication No. 2008140115, International Publication No. 2007052431, International Publication No. 2011134013, International Publication No. 2011157339, International Publication No. 2011086089, International Publication No. 20090113646, International Publication No. 2012020327, International Publication No. 2011051404, International Publication No. 2011004639 No., International Publication No. 2011073149, US Patent Publication No. 2012228583, US Patent Publication No. 2012212126, Japanese Patent Application Laid-Open No. 2012-069737, Japanese Patent Application Laid-Open No. 2012-195554, Japanese Patent Application Laid-Open No. 2009-114086, Japanese Patent Application Laid-Open No. 2003-81988, Japanese Patent Application Laid-Open No. 2002-302671 and Japanese Patent Application Laid-Open No. 2002-363552.

Hereinafter, specific examples of compounds preferable as phosphorescent dopants will be given, but the present invention is not limited thereto.

(1.2) Fluorescent Luminescent Dopant The fluorescent luminescent dopant according to the present invention is a compound capable of emitting light from an excited singlet. The type of the fluorescent dopant is not particularly limited as long as the emission from the excited singlet is observed. However, in the organic EL device according to the present embodiment, if the AIE molecule is used in combination with another fluorescent dopant that does not have aggregation-induced luminescence, the luminous efficiency may decrease. Therefore, a configuration in which no other fluorescent dopant is used in combination is more preferable.

Specific examples of the fluorescent dopant include anthracene derivatives, pyrene derivatives, chrysene derivatives, fluorantene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives, boron complexes, coumarin derivatives, etc. Examples thereof include pyran derivatives, cyanine derivatives, croconium derivatives, squalium derivatives, oxobenzoanthracene derivatives, fluorescein derivatives, rhodamine derivatives, pyrylium derivatives, perylene derivatives, polythiophene derivatives, and rare earth complex compounds.

Further, in recent years, light emitting dopants using delayed fluorescence have also been developed, and these may be used. Specific examples of the light emitting dopant using delayed fluorescence include the compounds described in International Publication No. 2011/156793, JP-A-2011-213443, JP-A-2010-93181 and the like.

(2) Host Compound The host compound according to the present invention is a compound mainly responsible for injection and transport of electric charges in the light emitting layer, and its own light emission is not substantially observed in the organic EL device. A compound having a phosphorescent quantum yield of less than 0.1 at room temperature (25 ° C.) is preferable, and a compound having a phosphorescent quantum yield of less than 0.01 is more preferable.

Among the compounds contained in the light emitting layer, the host compound preferably has a mass ratio of 20% or more in the light emitting layer. Further, the excited state energy of the host compound is preferably higher than the excited state energy of the light emitting dopant contained in the same layer. In the organic EL device according to the present embodiment, the light emitting layer may have a configuration in which a host compound is used in combination with an AIE molecule or a RISC compound, or a configuration in which a host compound is not used in combination may be used. For combination with the structures of the host compound, _{S 1} and _{T 1} of the host compound is preferably higher than _{S 1} and _{T 1} of the _{S 1} and _{T 1} and RISC compound of AIE molecules.

As the host compound, an appropriate type used for the light emitting layer of a general organic EL element can be used. The host compound may be a low molecular weight compound or a high molecular weight compound having a repeating unit. Further, it may be a compound having a reactive group such as a vinyl group or an epoxy group. As the host compound, one type may be used alone, or a plurality of types may be used in combination. When a plurality of types of host compounds are used in combination, the movement of electric charges can be easily adjusted, so that the efficiency of the organic EL device can be improved.

As the host compound, from the viewpoint of having hole transporting ability or electron transporting ability, preventing the wavelength of light emission from being lengthened, and further operating the organic EL element stably during high temperature driving or heat generation due to driving. Therefore, it is preferable to have a high glass transition temperature (Tg). The glass transition temperature of the host compound is preferably 90 ° C. or higher, more preferably 120 ° C. or higher. The glass transition temperature (Tg) is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

Specific examples of the host compound include, but are not limited to, the compounds described in the following documents. JP 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357977, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002. 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003 -3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002- 302516, 2002-305083, 2002-305084, 2002-308837, US Patent Publication No. 201301755553, US Patent Publication No. 20060280965, US Patent Publication No. 20050112407, US Patent Publication No. 20090017330, US Patent Publication No. 20090030202, US Patent Publication No. 20050238919, International Publication No. 200109234, International Publication No. 2009021126, International Publication No. 2008056746, International Publication No. 2004093207, International Publication No. 2005089025, International Publication No. 2007063796, International Publication No. 2007063754, International Publication No. 2004107822, International Publication No. 2005030900, International Publication No. 20061149666, International Publication No. 2009086028, International Publication No. 2009003898, International Publication No. 2012023947, Japanese Patent Application Laid-Open No. 2008-074939 No., Japanese Patent Application Laid-Open No. 2007-254297, EP2034538 and the like.

<< Ingredients >>
The organic layer of the organic EL element may further contain other inclusions. Other inclusions include, for example, elemental halogens and halogenated compounds such as bromine, iodine and chlorine, alkali metals such as Pd, Ca and Na, compounds of alkaline earth metals and transition metals, metal complexes and salts. Can be mentioned.

The amount of the other inclusions is not particularly limited, but is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 50 ppm or less, based on the total mass of the layer containing the contents. However, it is not limited to such a range depending on the purpose of improving the transportability of electrons and holes, the purpose of favoring the energy transfer of excitons, and the like.

<< Method of forming organic layer >>
The method for forming the organic layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) is not particularly limited, and is, for example, a vacuum deposition method or a wet method. A method (also called a wet process) or the like can be used.

Examples of the wet method include a spin coating method, a casting method, an inkjet method, a printing method, a die coating method, a blade coating method, a roll coating method, a spray coating method, a curtain coating method, and an LB method (Langmuir-Brojet method). Can be mentioned. As the wet method, a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an inkjet method, or a spray coating method is preferable because a homogeneous thin film can be easily obtained and the productivity is high. Used.

Examples of the liquid medium for dissolving or dispersing the material of the organic layer include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene and mesitylene. , Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO. As a dispersion method for dispersing the material of the organic layer, ultrasonic dispersion, high shear force dispersion, media dispersion and the like can be used.

The organic layer may be formed by using the same method for each layer, or may be formed by using a different method for each layer. When using a vacuum deposition method, deposition conditions may vary depending on the type of compound used, generally, a boat heating temperature of 50 to 450 ° C., vacuum of ¹⁰ -6 ^{to 10} -2 Pa, vapor deposition rate of 0.01 to 50 / Appropriate conditions can be set in the range of seconds, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

It is preferable that the organic layer is consistently prepared from the anode side layer to the cathode side layer by a single evacuation. However, it may be taken out in the middle and a different film forming method may be applied. When taking out in the middle, it is preferable to carry out the work at that time in a dry inert gas atmosphere.

"anode"
As the anode, a metal having a large work function (4 eV or more, preferably 4.5 eV or more), an alloy, an electrically conductive compound, or a mixture thereof as an electrode material is preferably used. Specific examples of such an electrode material include metals such as Au and conductive transparent materials such as _{CuI, indium tin oxide (ITO), SnO 2, and ZnO.} Further, a material such as IDIXO (In ₂ O _3- ZnO), which is amorphous and can produce a transparent conductive film, may be used.

The anode can be formed as a thin film by forming an electrode material into a film by vapor deposition, sputtering, or the like. When forming the anode, a pattern having a desired shape may be formed by a photolithography method. If high pattern accuracy is not required (about 100 μm or more), a mask may be used to form a pattern when vapor deposition or sputtering of an electrode substance is performed. Further, when a coatable electrode substance such as an organic conductive compound is used, a wet method such as a printing method or a coating method can also be used.

When the light emission of the organic EL element is taken out from the anode, it is preferable to make the transmittance of the anode larger than 10%. The sheet resistance as the anode is preferably several hundred Ω / □ or less. The thickness of the anode depends on the electrode material, but is usually 10 nm to 1 μm, preferably 10 to 200 nm.

"cathode"
As the cathode, a metal having a small work function (4 eV or less) (referred to as an electron-injectable metal), an alloy, an electrically conductive compound, or a mixture thereof as an electrode material is preferably used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O). ₃ ) Examples thereof include a mixture, indium, a lithium / aluminum mixture, aluminum, and a rare earth metal.

As the electrode material of the cathode, a mixture of an electron-injectable metal and a secondary metal which has a larger work function value and is a stable metal, for example, magnesium / More preferably, a silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like.

The cathode can be formed as a thin film by forming an electrode material into a film by vapor deposition, sputtering, or the like.

The sheet resistance as a cathode is preferably several hundred Ω / □ or less. The thickness of the cathode is usually 10 nm to 5 μm, preferably 50 to 200 nm.

It should be noted that either the anode or the cathode of the organic EL element is preferably transparent or translucent from the viewpoint of transmitting the emitted light to improve the emission brightness. For example, a transparent or translucent cathode can be produced by forming a metal, which is an electrode material of a cathode, with a film thickness of 1 to 20 nm, and then forming a film of the conductive transparent material on the metal. it can.

《Support board》
As the support substrate (also referred to as a substrate, substrate, substrate, support, etc.) of the organic EL element, glass, plastic, or the like can be used, and the type thereof is not particularly limited. The support substrate may be transparent or opaque. When light is taken out from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate include glass, quartz, and a transparent resin film. A particularly preferable support substrate is a resin film that can impart flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene and polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, and cellulose acetate propionate (CAP). ), Cellulose acetate phthalate (TAC), cellulose esters such as cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether. Ketone, polyimide, polyether sulfone (PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylates, Arton (trade name: JSR) ) Or a cycloolefin resin such as Apel (trade name: manufactured by Mitsui Chemicals, Inc.).

An inorganic film, an organic film, a hybrid film of an inorganic substance and an organic substance, or the like may be formed on the surface of the resin film. Resin film, water vapor transmission rate measured by the method based on JIS K 7129-1992 (25 ± 0.5 ℃ , relative humidity (90 ± 2)% RH) is 0.01g ^/ (m 2 · 24h) or less is preferably a barrier film, JIS K oxygen permeability measured in compliance with the method provided in 7126-1987 is ^{10 -3 ml / (m 2 ·} 24h · atm) or less and a water vapor permeability of 10 ^{- 5 g / (m 2 · 24h} ) and more preferably less which is a high barrier film.

The material of the barrier film formed on the barrier film may be any material having a function of suppressing the infiltration of substances that cause deterioration of the organic EL element, such as water and oxygen, and for example, silicon oxide, silicon dioxide, and nitrided material. Silicon or the like can be used. It is preferable that the barrier film has a laminated structure of an inorganic layer and an organic layer in order to improve the fragility. The stacking order of the inorganic layer and the organic layer is not particularly limited, but it is preferable that the inorganic layer and the organic layer are alternately laminated a plurality of times.

The method for forming the barrier film is not particularly limited, and is, for example, a vacuum vapor deposition method, a sputtering method, a reactive sputtering method, a molecular beam epitaxy method, a cluster ion beam method, an ion plating method, a plasma polymerization method, and an atmospheric pressure. A plasma polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method and the like can be used. As a method for forming the barrier film, an atmospheric pressure plasma polymerization method as described in JP-A-2004-68143 is particularly preferable.

As the opaque support substrate, for example, a metal plate such as aluminum or stainless steel, a film, a resin substrate, a ceramic substrate, or the like can be used.

《Seal》
Examples of the method of sealing the organic EL element include a method of adhering the sealing member and the electrode or the support substrate with an adhesive. The sealing member may be arranged so as to cover the display area of the organic EL element, and may have an intaglio shape or a flat plate shape. Examples of the method for processing the sealing member into a concave shape include sandblasting and chemical etching. The transparency and electrical insulation of the sealing member are not particularly limited.

Specific examples of the sealing member include a glass plate, a polymer plate / film, a metal plate / film, and the like. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate / film include those formed of polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like. Examples of the metal plate / film include those formed of metals and alloys such as stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

As the sealing member, a polymer film or a metal film can be preferably used from the viewpoint that the organic EL element can be thinned. As the polymer film, the oxygen permeability measured by the method according to JIS K 7126-1987 is 1 × 10 ^-3 ml / m ² / 24h or less, and the water vapor permeability measured by the method according to JIS K 7129-1992. The degree (25 ± 0.5 ° C., relative humidity (90 ± 2)%) ^{is preferably 1 × 10 -3} g / (m ² / 24h) or less.

Examples of the adhesive include a photocurable adhesive having a reactive vinyl group such as an acrylic acid-based oligomer and a methacrylic acid-based oligomer, a thermosetting adhesive, a moisture-curable adhesive such as 2-cyanoacrylic acid ester, and an epoxy-based adhesive. Examples thereof include thermosetting adhesives and chemically curable (two-component mixed) adhesives. Further, examples thereof include hot melt type adhesives such as polyamide, polyester and polyolefin, and cationic curable type ultraviolet curable epoxy resin adhesives.

As the adhesive, since the organic EL element may be deteriorated by heat treatment, an adhesive that can be adhesively cured from room temperature to 80 ° C. is preferable. Further, the adhesive may be one in which a desiccant is dispersed. The adhesive may be applied to the sealing portion by using a commercially available dispenser or by printing as in screen printing.

Further, as a method of sealing the organic EL element, a method of forming a sealing film covering the organic layer and the electrode on the outside of the electrode provided on the opposite side of the support substrate can also be used. The sealing film may be provided by any of an inorganic film, an organic film, a hybrid film of an inorganic substance and an organic substance, and the like. The material of the sealing film may be any material having a function of suppressing the infiltration of substances that cause deterioration of the organic EL element such as water and oxygen, and for example, silicon oxide, silicon dioxide, silicon nitride and the like are used. Can be done. It is preferable that the sealing film has a laminated structure of an inorganic layer and an organic layer in order to improve the brittleness.

The method for forming the sealing film is not particularly limited, and for example, a vacuum deposition method, a sputtering method, a reactive sputtering method, a molecular beam epitaxy method, a cluster ion beam method, an ion plating method, a plasma polymerization method, and a large method are used. A pressure plasma polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method and the like can be used.

In the gap between the sealing member and the display region of the organic EL element, an inert gas such as nitrogen or argon or an inert liquid such as fluorinated hydrocarbon or silicon oil is injected into both the gas phase and the liquid phase. It is preferable to do so. Further, the gap between the sealing member and the display region of the organic EL element may be a vacuum, or a hygroscopic compound may be sealed.

Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide, etc.) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, etc.). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchlorates (eg, perchloric acid) Barium, magnesium perchlorate, etc.) and the like. Anhydrous salts are preferably used for sulfates, metal halides and perchloric acids.

《Use》
The organic EL element according to the present invention can be used as a display device, a display, and various light emitting light sources. Examples of the light emitting light source include a lighting device (household lighting, interior lighting), a clock backlight, a liquid crystal backlight, a signage advertisement light source, a signal light source, an optical storage medium light source, and an electrophotographic copying machine light source. Examples thereof include a light source of an optical communication processor and a light source of an optical sensor. In particular, it can be effectively used as a backlight of a liquid crystal display device and a light source for lighting.

(Display device)
Specifically, the organic EL element according to the present invention can be used as a pixel of a display device. The display device may be a single-color display device or a multi-color display device. Hereinafter, a multicolor display device will be described as an example of a display device including the organic EL element of the present invention.

As the configuration of the organic EL element provided in the display device, various configurations can be adopted including the above-mentioned element configuration example. When a DC voltage is applied to the multicolor display device, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. When an AC voltage is applied, light emission can be observed only when the anode is in the + state and the cathode is in the-state. The AC waveform to be applied is not particularly limited.

The multicolor display device can be used as, for example, a display device, a display, and various light emitting light sources. Examples of display devices and displays include televisions, personal computers, mobile devices, AV devices, teletext displays, information displays in automobiles, and the like. In display devices and displays, full-color display is possible by using three types of organic EL elements, which emit blue light, red light, and green light. It can be used as a display device for reproducing a still image or a moving image, and the driving method for reproducing a moving image may be either a simple matrix (passive matrix) method or an active matrix method.

FIG. 2 is a schematic view showing an example of a display device composed of an organic EL element. This display device displays image information by emitting light from an organic EL element. The display 1 is a wiring unit that electrically connects a display unit A having a plurality of pixels, a control unit B that scans an image of the display unit A based on image information, and the display unit A and the control unit B. Etc. are provided.

The control unit B sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. Then, the pixels of each scanning line emit light in sequence according to the image data signal by the scanning signal, and the image information is displayed by the display unit A.

FIG. 3 is a schematic view of the display unit A. The display unit A has a plurality of pixels 3, a plurality of scanning lines 5, and a plurality of data lines 6 on the substrate. FIG. 3 shows a case where the light from each pixel 3 is taken out in the downward direction (in the direction of the white arrow).

The scanning line 5 and the data line 6 of the wiring portion are each made of a conductive material. The scanning line 5 and the data line 6 are orthogonal to each other in a grid pattern and are connected to each pixel 3 at orthogonal positions. When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full-color display is possible by appropriately arranging the red emission color pixels, the green pixels, and the blue pixels on the substrate.

FIG. 4 is a schematic diagram of pixels. The pixel 3 includes an organic EL element 10, a switching transistor 11, a drive transistor 12, a capacitor 13, and the like. Organic EL elements 10 having emission colors of red, green, and blue are used for the plurality of pixels 3 provided on the substrate.

In FIG. 4, an image data signal is applied from the control unit B to the drain of the switching transistor 11 via the data line 6. Then, when a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the switching transistor 11 is driven on, and the image data signal applied to the drain is driven with the capacitor 13. It is transmitted to the gate of the transistor 12.

By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive transistor 12 is driven on. In the drive transistor 12, the drain is connected to the power supply line 7, and the source is connected to the electrode of the organic EL element 10. A current is supplied to the organic EL element 10 from the power supply line 7 according to the potential of the image data signal applied to the gate.

When the control unit B performs sequential scanning and the scanning signal moves to the next scanning line 5, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 retains the potential of the charged image data signal. Therefore, the drive of the drive transistor 12 is kept on, and the organic EL element 10 continues to emit light until the next scan signal is applied. Then, when the scanning signal is applied next by the sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.

In this way, the light emission of the organic EL element 10 is performed for each of the plurality of pixels by providing the switching transistor 11 and the drive transistor 12, which are active elements, for the organic EL element 10 used for each of the plurality of pixels 3. It can be configured by the method described. Such a light emitting method is called an active matrix method.

The light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-valued image data signal having a plurality of gradation potentials, or by turning on and off a predetermined amount of light emission by the binary image data signal. It may emit light. Further, the potential of the capacitor 13 may be continuously maintained until the application of the next scanning signal, or may be discharged immediately before the application of the next scanning signal.

The light emitting method of the display device is not limited to the above active matrix method, and may be a passive matrix method in which the organic EL element emits light in response to the data signal only when the scanning signal is scanned.

FIG. 5 is a schematic view of a passive matrix type full-color display device. In FIG. 5, the plurality of scanning lines 5 and the plurality of image data lines 6 are provided in a grid pattern so as to face each other with the pixel 3 interposed therebetween. When the scanning signal of the scanning line 5 is applied by the sequential scanning, the pixel 3 connected to the scanning line 5 emits light according to the image data signal. According to the passive matrix method, it is not necessary to provide an active element in the pixel 3, and the manufacturing cost is reduced.

<Lighting device>
Specifically, the organic EL element according to the present invention can be used as a light source for various lighting devices. The lighting device may be a device that produces an appropriate light source color, but a device that produces a white light source color is preferable.

White luminescence can be obtained by simultaneously emitting a plurality of luminescent colors with a plurality of luminescent compounds and mixing the colors. The combination of emission colors may be a combination of the three primary colors of red, green and blue, or a combination of complementary colors such as blue and yellow and blue-green and orange. Further, a dye that emits light from a luminescent compound as excitation light may be used in combination, or a color filter may be used.

In the lighting device, organic EL elements that generate emission colors of each color may be arranged on an array to generate white emission, or the emission color of the organic EL element itself may be whitened. When the emission color of the organic EL element itself is white, patterning may be performed only on the light emitting layer or the like, and the electrodes or the like may be collectively formed on one surface.

FIG. 6 is a schematic view of the lighting device. Further, FIG. 7 is a schematic view of the lighting device. The lighting device can be formed, for example, by covering the organic EL element 101 according to the present invention with a glass cover 102 or the like having a thickness of about 300 μm. By sealing the pair of electrodes 105 and 107 and the organic layer 106 with a glass cover 102 or the like coated with a sealing material around them, it is possible to prevent the organic layer 106 or the like from being deteriorated by oxygen or moisture in the atmosphere. Can be done. For example, sealing is performed in a glove box under a nitrogen atmosphere (under an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more), and the glass cover 102 is filled with an inert gas 108 such as nitrogen gas or captured. It is possible to install a liquid agent 109 or the like.

The structure, manufacturing method, use, etc. of the organic EL device according to the above embodiment are not limited to the above description, and other known configurations and other known configurations are used as long as the gist of the present invention is not deviated. The manufacturing method can be applied, and the present invention can be used for other purposes. For example, Japanese Patent Application Laid-Open No. 2013-089608, Japanese Patent Application Laid-Open No. 2014-120334, Japanese Patent Application Laid-Open No. 2015-201508, and the like may be referred to with respect to known configurations, manufacturing methods, uses, and the like of organic EL devices.

《Luminescent thin film》
Next, the luminescent thin film according to this embodiment will be described. The luminescent thin film according to the present embodiment is composed of a compound (RISC compound) in which the energy difference between the lowest excited singlet energy level and the lowest excited triplet energy level is 0.5 eV or less (RISC compound) and an aggregation-induced luminescent molecule (AIE molecule). ) And. For example, by forming a functional thin film containing a RISC compound and an AIE molecule on a substrate, a luminescent functional thin film that can be used for various purposes can be formed. The concentration of the AIE molecule in the luminescent thin film can be, for example, 0.1% by mass or more and 99.9% by mass or less. The concentration of the RISC compound in the luminescent thin film can be, for example, 0.1% by mass or more and 99.9% by mass or less.

The luminescent thin film according to the present embodiment can be used as a material for, for example, an organic EL element, a photoelectric conversion element, an organic functional thin film, and the like. It can also be used as a light emitting element constituting the display device or the lighting device. The method for forming the luminescent thin film of the present invention is not particularly limited, and a conventionally known forming method such as a vacuum vapor deposition method or a wet method can be used. In addition to the RISC compound and the AIE molecule, other luminescent compounds and host compounds may be blended in the luminescent thin film to be formed.

Examples of the wet method include a spin coating method, a casting method, an inkjet method, a printing method, a die coating method, a blade coating method, a roll coating method, a spray coating method, a curtain coating method, and an LB method (Langmuir-Brojet method). Can be mentioned. As the wet method, a method having high suitability for a roll-to-roll method such as a die coating method, a roll coating method, an inkjet method, or a spray coating method is preferable because a homogeneous thin film can be easily obtained and the productivity is high. Used.

Examples of the liquid medium for dissolving or dispersing the RISC compound and AIE molecule include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene and xylene, and the like. Examples include aromatic hydrocarbons such as mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO. As a dispersion method for dispersing the material, ultrasonic dispersion, high shear force dispersion, media dispersion and the like can be used.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, "%" in an Example means "mass%" unless otherwise specified.

(Fluorescent compound)
The fluorescent compounds (A-1, A-2) used in the examples are shown below. Compound A-1 and Compound A-2 are conventional fluorescent compounds having no aggregation-induced luminescence.

(RISC compound)
The RISC compounds (B-1, B-2, B-3) used in the examples are shown below. Incidentally, Delta] E _st of RISC Compound B-1 is 0.09 eV, Delta] E _st of RISC Compound B-2 is 0.11 eV, Delta] E _st of RISC Compound B-3 is 0.25 eV.

(Hole transport material)
The hole transport material (HT-1) used in the examples is shown below.

(Electronic transport material)
The electron transport materials (ET-1, ET-2) used in the examples are shown below.

(Host compound)
The host compounds (H-1, H-2) used in the examples are shown below.

(AIE molecule)
The AIE molecules (AIE-1, AIE-2, AIE-3, AIE-4) used in the examples are shown below. The AIE molecule is a fluorescent compound that emits strong fluorescence by aggregating to form an aggregate.

Among the compounds used in the examples, AIE-1 and AIE-2 are described in the methods described in publications (Qin W., et al., Chem. Commun., 2015, 51, 7321-7324). Synthesized based on. In addition, AIE-3 was synthesized based on the method described in the publication (Kim JY, et al., Adv. Mater. 2013, 25, 2666-2671). In addition, AIE-4 was synthesized based on the method described in publications (Chen B., et al., Chem. Eur. J., 2014, 20, 1931-1939). For other compounds, commercially available products (manufactured by Wako Pure Chemical Industries, Ltd.) were used.

[Example 1]
An organic EL device was prepared using the post-crosslinked compound HT-1 for the hole transport layer and the luminescent compound shown in Table 1 for the light emitting layer, and the luminous efficiency was evaluated.

<Manufacturing of organic EL element 1-1>
(Manufacturing of anode)
ITO (indium tin oxide) was formed as an anode on a 100 mm × 100 mm × 1.1 mm transparent support substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) to a thickness of about 100 nm, and patterning was performed. Then, after ultrasonic cleaning with isopropyl alcohol and drying with dry nitrogen gas, UV ozone cleaning was performed for 5 minutes.

(Preparation of hole transport layer)
Subsequently, a solution obtained by diluting poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT: PSS, manufactured by Heleus, trade name: CLEVIOS P VP AI 4083) with pure water to 70% was prepared. , A film was formed on the anode prepared on the transparent support substrate by the spin coating method under the conditions of 3000 rpm and 30 seconds. Then, it was dried at 200 ° C. for 1 hour to form a first hole transport layer having a film thickness of 30 nm. Next, this substrate was transferred to a nitrogen atmosphere, and a coating solution obtained by dissolving 9.0 mg of compound HT-1 in 1.1 g of chlorobenzene was placed on the first hole transport layer at 1500 rpm for 30 seconds. The film was formed by the spin coating method. Then, it was irradiated with ultraviolet light for 180 seconds to perform photopolymerization and cross-linking of the post-crosslinking compound HT-1 to form a second hole transport layer having a film thickness of about 20 nm.

(Preparation of light emitting layer)
Subsequently, a coating film obtained by dissolving 6.75 mg of the host compound H-1 and 1.69 mg of the fluorescent luminescent compound A-1 in 1.1 g of chlorobenzene under a nitrogen atmosphere was applied to the second hole transport layer. A film was formed on the film by the spin coating method under the conditions of 1500 rpm and 30 seconds. Then, the solvent was completely removed by heating and drying at 130 ° C. under vacuum to form a light emitting layer having a film thickness of about 50 nm.

(Preparation of electron transport layer)
Subsequently, after attaching the transparent support substrate on which the light emitting layer was formed to the vacuum vapor deposition apparatus, the vacuum chamber ^{was depressurized to 4 × 10 -4} Pa, and the compound ET-1 was placed on the light emitting layer at 0.1 nm / sec. By vapor deposition, an electron transport layer having a film thickness of about 35 nm was formed.

(Preparation of electron injection layer / cathode)
Subsequently, using a vacuum vapor deposition apparatus, lithium fluoride was vapor-deposited on the electron transport layer to form an electron injection layer having a film thickness of about 1.0 nm. Next, aluminum was vapor-deposited on the electron-injected layer to form a cathode having a film thickness of about 110 nm.

(Sealing)
An epoxy-based photo-curing adhesive (Lux Track LC0629B, manufactured by Toa Synthetic Co., Ltd.) containing a hygroscopic compound that adsorbs oxygen and moisture is applied to the peripheral edge of the sealing glass cover, and the glass cover is transparent. The electrode and the organic layer formed on the support substrate were covered, and the peripheral portion coated with the epoxy-based photocurable adhesive as a sealing material was brought into close contact with the transparent support substrate. Then, UV light was irradiated from the transparent support substrate side to the portion where the electrode and the organic layer were not formed, and the adhesive was cured to obtain a sealed organic EL element 1-1.

<Manufacturing of organic EL element 1-2>
The organic EL device 1- is the same as the organic EL device 1-1 except that 8.01 mg of the host compound H-1 and 0.42 mg of the RISC compound B-1 are used as the coating liquid for forming the light emitting layer. 2 was prepared.

<Manufacturing of organic EL elements 1-3>
Organic EL device 1 except that 6.33 mg of the host compound H-1, 0.42 mg of the RISC compound B-1 and 1.69 mg of the fluorescent luminescent compound A-1 were used as the coating liquid for forming the light emitting layer. Organic EL elements 1-3 were produced in the same manner as in -1.

<Manufacturing of organic EL elements 1-4 to 1-7>
Organic EL devices 1-4 to 1-7 were produced in the same manner as the organic EL devices 1-3 except that the types of luminescent compounds were replaced with the compounds shown in Table 1.

<Evaluation of luminous efficiency>
At room temperature (25 ° C.), the ^{organic EL element is lit at a constant current density of 2.5} mA / cm 2, the emission brightness is measured with a spectral radiance meter CS-2000 (manufactured by Konica Minolta), and the luminous efficiency (external). Extraction quantum efficiency) was calculated. The results are shown in Table 1. The luminous efficiency in the table represents a relative value with the measured value of the organic EL element 1-3 as 100.

As shown in Table 1, 20 organic EL elements 1-1 using only the fluorescent luminescent compound A-1 having no aggregation-induced quenching as the luminescent compound and 20 using only the RISC compound B-1 at a concentration of 20% by mass. In the organic EL element 1-2 used at a concentration of mass%, light emission was not substantially observed, and it is considered that concentration quenching occurred due to the aggregation of the compounds. In the organic EL element 1-3 in which the RISC compound B-1 and the fluorescent compound A-1 are used in combination as the light emitting compound, the organic EL element in which the fluorescent compound A-1 or the RISC compound B-1 is used alone is used. Compared with 1-1 to 1-2, the light emission efficiency was improved to some extent.

On the other hand, in the organic EL devices 1-4 to 1-7 in which the AIE molecule was added at the same concentration instead of the fluorescent compound A-1 and used in combination with the RISC compound, the organic EL devices 1-4 to 1-7 were compared with the organic EL devices 1-3. Further improvement in luminous efficiency was observed. From this result, the conventional fluorescent luminescent compound is in an aggregated state, and even if the concentration is high enough to cause quenching, the AIE molecule can sufficiently emit light, and when used in combination with the RISC compound, it emits light. It was confirmed that the efficiency was greatly improved.

[Example 2]
In order to confirm the component that caused light emission in Example 1, a sample of a light emitting thin film was prepared using the same light emitting compound as in Example 1, and the emission spectrum was evaluated.

<Preparation of sample 2-1>
A glass substrate of 300 mm × 300 mm × 1.1 mm was subjected to UV ozone cleaning treatment for 10 minutes. Then, in a nitrogen atmosphere, the coating liquid used for forming the light emitting layer of the organic EL element 1-1 was formed on the substrate by a spin coating method under the conditions of 1000 rpm and 30 seconds. Then, sealing was performed in the same procedure as for the organic EL element 1-1 to obtain sample 2-1.

<Preparation of sample 2-2>
Sample 2-Similar to Sample 2-1 except that the coating liquid used to form the light emitting layer of the organic EL element 1-2 was used and the fluorescent light emitting compound A-1 was replaced with RISC compound B-1. 2 was prepared.

<Preparation of sample 2-3>
Sample 2-3 was prepared in the same manner as in Sample 2-2 except that RISC compound B-1 was replaced with RISC compound B-2.

<Preparation of samples 2-4 to 2-5>
Samples 2-4 to 2-5 were prepared in the same manner as in Sample 2-1 except that the fluorescent compound A-1 was replaced with AIE-1 or AIE-2.

<Preparation of samples 2-6 to 2-9>
Samples were used in the same manner as in Sample 2-1 except that the coating liquid used for forming the light emitting layer of the organic EL elements 1-4 to 1-7 was used and the type of the light emitting compound was replaced with the compound shown in Table 2. 2-6 to 2-9 were prepared.

<Evaluation of spectrum>
The sample was made to emit light using the excitation method shown in Table 2, and the emission spectrum was measured at room temperature with a spectrofluorometer (F-7000, manufactured by Hitachi High-Tech Science Co., Ltd.) to confirm the maximum emission wavelength. Samples 2-1 to 2-5 were photoexcited with light in the wavelength region including the visible light region, and samples 2-6 to 2-9 were current-excited at ^{2.5 mA / cm 2.}

As a result, the emission maximum wavelengths of the samples 2-6 to 2-9 in which the RISC compound and the AIE molecule were used together as the luminescent compound were the emission maximum wavelengths of the samples 2-4 and 2-5 using only the AIE molecule, respectively. It matched. Since luminescence derived from the AIE molecule was detected in the samples 2-6 to 2-9, it was speculated that the excitons may have transferred energy from the RISC compound to the AIE molecule.

[Example 3]
An organic EL device was prepared using the post-crosslinked compound HT-1 for the hole transport layer and the luminescent compound shown in Table 3 for the light emitting layer, and the luminous efficiency was evaluated.

<Manufacturing of organic EL elements 3-1 to 3-5>
Organic EL devices 3-1 to 3-5 were produced in the same manner as the organic EL devices 1-1 except that the types of luminescent compounds were replaced with the compounds shown in Table 3.

<Evaluation of luminous efficiency>
^{Similar to Example 1, the organic EL element is lit at a constant current density of 2.5} mA / cm 2 at room temperature (25 ° C.), and the luminous brightness is measured by a spectral radiance meter CS-2000 (manufactured by Konica Minolta). Luminous efficiency (external extraction quantum efficiency) was determined by measurement. The results are shown in Table 3. The luminous efficiency in the table represents a relative value with the measured value of the organic EL element 3-3 as 100.

As shown in Table 3, no light emission was substantially observed in the organic EL device 3-1 using only the fluorescent compound A-2 having no aggregation-induced luminescence as the luminescent compound at a concentration of 20% by mass. On the other hand, in the organic EL devices 3-4 to 3-5 in which the AIE molecule was added at the same concentration instead of the fluorescent compound A-2 and used in combination with the RISC compound, the organic EL devices 3-4 to 3-5 were compared with the organic EL device 3-3. High luminous efficiency was obtained. Therefore, when increasing the concentration of the fluorescent compound for the purpose of improving the luminous efficiency, it is presumed that the method of using the AIE molecule in combination is effective.

[Example 4]
In order to confirm the component that caused light emission in Example 3, a sample of a light emitting thin film was prepared using the same light emitting compound as in Example 3, and the emission spectrum was evaluated.

<Preparation of sample 4-1>
In the same manner as in Example 2, a glass substrate of 300 mm × 300 mm × 1.1 mm was subjected to UV ozone cleaning treatment for 10 minutes. Then, in a nitrogen atmosphere, the coating liquid used for forming the light emitting layer of the organic EL element 3-1 was formed on the substrate by a spin coating method under the conditions of 1000 rpm and 30 seconds. Then, sealing was performed in the same procedure as for the organic EL element 1-1 to obtain sample 4-1.

<Preparation of sample 4-2>
The coating liquid used for forming the light emitting layer of the organic EL element 3-2 was used, and the same as that of sample 4-1 except that the fluorescent compound A-2 was replaced with RISC compound B-3, and sample 4- 2 was prepared.

<Preparation of samples 4-3-4-4>
Samples 4-3-4-4 were prepared in the same manner as in Sample 4-1 except that the fluorescent compound A-2 was replaced with AIE-3 or AIE-4.

<Preparation of samples 4-5-4-6>
A sample was used in the same manner as in Sample 4-1 except that the coating liquid used for forming the light emitting layer of the organic EL elements 3-4 to 3-5 was used and the type of the luminescent compound was replaced with the compound shown in Table 4. 4-5-4-6 were prepared.

<Evaluation of spectrum>
In the same manner as in Example 2, the sample was made to emit light using the excitation method shown in Table 4, and the emission spectrum was measured at room temperature with a spectrofluorometer (Hitachi High-Tech Science Co., Ltd., F-7000) to maximize the emission. The wavelength was confirmed. Samples 4-1 to 4-4 were photoexcited with light in a wavelength region including the visible light region, and samples 4-5 to 4-6 were current-excited at ^{2.5 mA / cm 2.}

As a result, as the emission maximum wavelength of the sample 4-5 in which the RISC compound and the AIE molecule are used in combination as the luminescent compound, the emission maximum wavelength of the sample 4-2 using only the RISC compound B-3 or only the AIE molecule is used. It was confirmed that the samples were located at two locations close to the maximum emission wavelength of the sample 4-3. Similarly, the sample 4-6 in which the RISC compound and the AIE molecule are used in combination as the luminescent compound is also located at two locations that are close to the emission maximum wavelength of the sample 4-2 and the emission maximum wavelength of the sample 4-4. It was confirmed that. Therefore, it is inferred that not all of the triplet excitons generated in the RISC compound are energy-transferred to the AIE molecule, and some of them may cause light emission on the RISC compound.

[Example 5]
An organic EL device containing an AIE molecule as a luminescent compound was prepared, and resistance to water and oxygen was evaluated.

<Manufacturing of organic EL element 5-1>
The organic EL device except that the compound ET-1 used for forming the electron transport layer was replaced with the compound ET-2, the host compound H-1 was replaced with the host compound H-2, and the device was completed without sealing. The organic EL element 5-1 was produced in the same manner as in 1-3.

<Manufacturing of organic EL element 5-2>
The organic EL device except that the compound ET-1 used for forming the electron transport layer was replaced with the compound ET-2, the host compound H-1 was replaced with the host compound H-2, and the device was completed without sealing. The organic EL element 5-2 was manufactured in the same manner as in 1-4.

<Evaluation of resistance to moisture and oxygen>
The luminous efficiency of the organic EL element immediately after production and the luminous efficiency of the organic EL element after being left in the air for 24 hours were determined, respectively, and the resistance to moisture and oxygen was evaluated based on the decrease in luminous efficiency. The luminous efficiency (external extraction quantum efficiency) was determined in the same manner as in Example 1. The results are shown in Table 5. The luminous efficiency in the table represents a relative value with the measured value immediately after fabrication (0 hours later) as 100 for each organic EL element.

As shown in Table 5, in the organic EL element 5-2 containing AIE molecules in the light emitting layer, high luminous efficiency was confirmed even after being left in the atmosphere. This factor is not clear, but it is because the diameter of each luminescent material is increased by forming aggregates of AIE molecules, and the contact area and the number of collisions with water molecules and oxygen that cause deterioration are reduced. Can be inferred. Similar results were obtained when Dp-1 to Dp-59 described in the present specification were used as the phosphorescent metal complex used in this case.

1 Display 3 Pixels 5 Scanning line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Condenser 101 Organic EL element in the lighting device 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with transparent electrode 108 Nitrogen Gas 109 Water trapping agent A Display unit B Control unit

Claims (6)

It includes an anode, a cathode, and a light emitting layer provided between the anode and the cathode, and the energy difference between the lowest excited single-term energy level and the lowest excited triple-term energy level is 0 in the light emitting layer. An organic electroluminescence device containing a compound having a concentration of .5 eV or less and an aggregation-induced luminescent molecule. The organic electroluminescence device according to claim 1, wherein the compound is a Π-conjugated compound represented by the following general formula (A).

[However, in the general formula (A), A represents an electron acceptor site, D represents an electron donor site, L represents a divalent linking group, and l and m are independent of each other. , Represents an integer of 1-4. ] The organic electroluminescence device according to claim 1, wherein the aggregation-induced luminescent molecule is a tetraphenylethylene derivative or a silol derivative. A luminescent thin film containing a compound having an energy difference of 0.5 eV or less between the lowest excited singlet energy level and the lowest excited triplet energy level and aggregation-induced luminescent molecules. A display device including the organic electroluminescence element according to any one of claims 1 to 3. A lighting device comprising the organic electroluminescence element according to any one of claims 1 to 3.

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