WO2018159663A1

WO2018159663A1 - Light-emitting material, organic light-emitting element and compound

Info

Publication number: WO2018159663A1
Application number: PCT/JP2018/007464
Authority: WO
Inventors: 啓太辻; 陽一 ▲土▼屋; 安達　千波矢
Original assignee: 国立大学法人九州大学
Priority date: 2017-02-28
Filing date: 2018-02-28
Publication date: 2018-09-07

Abstract

Provided are: (A) a compound having a structure in which at least 2 types of acceptor groups are linked; (B) a compound having a structure in which a weak donor group and a weak acceptor group are linked; and (C) a compound having a structure in which 2 or more donor groups are linked. The compounds are useful as light-emitting materials.

Description

Luminescent materials, organic light emitting devices and compounds

The present invention relates to a light emitting material and an organic light emitting device using the light emitting material. The present invention also relates to compounds used for these light emitting materials and organic light emitting devices.

Researches for increasing the light emission efficiency of organic light emitting devices such as organic electroluminescence devices (organic EL devices) are being actively conducted. In particular, various efforts have been made to increase the light emission efficiency by newly developing and combining electron transport materials, hole transport materials, light emitting materials, and the like constituting the organic electroluminescence element. Among them, research on organic electroluminescence devices using thermally activated delayed fluorescent materials can also be found.
Thermally activated delayed fluorescent material is the transition from excited triplet state to excited singlet state due to the absorption of thermal energy when transitioning to excited triplet state. It is a compound that emits fluorescence when returning to the back. The fluorescence due to such a route is called delayed fluorescence because it is observed later than the fluorescence from the excited singlet state (normal fluorescence) directly generated without passing through the reverse intersystem crossing. For example, in the current excitation of a compound, since the generation probability of an excited singlet state and an excited triplet state is 25%: 75%, there is a limit to the improvement of the light emission efficiency only with the fluorescence generated directly from the excited singlet state. is there. On the other hand, in the thermally activated delayed fluorescent material, the excited triplet state energy generated with a probability of 75% can also be effectively used for fluorescence emission, so that higher luminous efficiency can be expected.
A conventional typical thermally activated delayed fluorescent material includes a structure (DA structure) in which a donor site (D) exhibiting electron donor properties and an acceptor site (A) exhibiting electron acceptor properties are bonded. Known (for example, Non-Patent Documents 1 to 4). A wide variety of groups have been known as groups exhibiting electron donor properties and electron acceptor properties, and new groups have been developed. Then, by selecting a donor site (D) from a group exhibiting electron donor properties, selecting an acceptor site (A) from a group exhibiting electron acceptor properties, and designing a molecule that combines them, Various attempts have been made to develop compounds having good luminescent properties.

However, the development of a light emitting material by such a conventional method involves classifying each group as either a group exhibiting an electron donor property or a group exhibiting an electron acceptor property, and then designing a molecule. Therefore, there is a problem that light emitting materials that can be developed are limited. In particular, it is considered difficult to provide a practical heat-activated delayed fluorescent material without using at least one of a group showing a relatively strong electron donor property or a group showing a relatively strong electron acceptor property. Therefore, the range of molecular design is greatly restricted. Therefore, the present inventors have conducted intensive studies in consideration of designing a molecule of a luminescent material from a new viewpoint different from the conventional method.

As a result of diligent studies to achieve the above object, the present inventors have completed a new invention described below.
[1] A light emitting material comprising a compound that satisfies any of the following conditions (A) to (C).
(A) A compound having a structure in which two different acceptor groups are bonded to each other.
(B) A compound having a structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked.
(C) A compound having a structure in which two different donor groups are bonded to each other.
[2] The light emitting material according to [1], which is a delayed fluorescent material.
[3] luminescent material according to the minimum difference Delta] E _ST excited singlet energy level _{E S1} and the lowest excited triplet energy level _{E T1} compound is less than 0.4 eV, [1] or [2].
[4] The light-emitting material according to any one of [1] to [3], wherein the compound satisfies the condition (A).
[5] The light emitting material according to any one of [1] to [3], wherein the compound satisfies the condition (B).
[6] The light emitting material according to any one of [1] to [3], wherein the compound is represented by the following general formula (1).

[In the general formula (1), R ¹ to R ⁸ each independently represents a hydrogen atom or a substituent, and R ⁹ represents a substituent. R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , R ⁷ and R ⁸ , R ⁴ and R ⁹ , R ⁵ and R ⁹ are respectively They may be bonded to each other to form a cyclic structure. Z represents an electron withdrawing group. However, the general formula (1) satisfies the above (A) or (B). ]
[7] Z in the general formula (1) is> C = O,> C = C (CN) ₂ ,> BR ¹⁰ ,> SO ₂ ,> C (CF ₃ ) ₂ ,> P (= O ) The luminescent material according to [6], wherein R is ¹¹ or S, and R ¹⁰ and R ¹¹ each independently represent a substituent and satisfy the above (A) or (B).
[8] The light emitting material according to [6], wherein Z in the general formula (1) is> C═O.
[9] The light emitting material according to any one of [6] to [8], wherein R ⁹ in the general formula (1) is an acceptor group and satisfies the above (A).
[10] The light emitting material according to [9], wherein R ⁹ in the general formula (1) is a substituted or unsubstituted triazinyl group.
[11] The light emitting material according to [10], wherein R ⁹ in the general formula (1) is a substituted or unsubstituted diaryltriazinyl group.
[12] The light-emitting material according to any one of [6] to [8], wherein R ¹ in the general formula (1) is a donor group and satisfies the (B).
[13] The light emitting material according to [12], wherein R ¹ in the general formula (1) is a substituted or unsubstituted carbazolyl group.
[14] The light emitting material according to [12] or [13], wherein R ⁹ in the general formula (1) is a substituted or unsubstituted aryl group.
[15] The light-emitting material according to any one of [1] to [3], wherein the compound satisfies the condition (C).
[16] The light-emitting material according to [15], wherein the compound includes a structure in which an optionally substituted acridan ring and an optionally substituted dibenzofuran ring are bonded.
[17] The light-emitting material according to [15], wherein the compound includes a structure in which two optionally substituted acridan rings are bonded to an optionally substituted dibenzofuran ring.
[18] The light-emitting material according to [16] or [17], wherein the nitrogen atom constituting the acridan ring is bonded to the dibenzofuran ring.
[19] The light-emitting material according to any one of [16] to [18], wherein the acridan ring is bonded to the 4-position of the dibenzofuran ring.
[20] The light emitting material according to any one of [15] to [19], wherein the compound has a structure represented by the following general formula (2).

[In General Formula (2), D represents a dibenzofuran ring group which may be substituted or a dibenzothiophene ring group which may be substituted. R ¹¹ to R ²⁰ each independently represents a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , R ¹⁹ and R ²⁰ , R ²⁰ And R ¹¹ may be bonded to each other to form a cyclic structure. n represents an integer of 1 to 4. However, the general formula (2) satisfies the above (C). ]
[21] The luminescent material according to [20], wherein n is 2.
[22] The light-emitting material according to [21], wherein D represents an optionally substituted dibenzofuran-4,6-diyl group or an optionally substituted dibenzothiophene-4,6-diyl group.
[23] The luminescent material according to [20], wherein n is 1.
[24] An organic light-emitting device comprising the light-emitting material according to any one of [1] to [23].
[25] The organic light-emitting device according to [24], which is an organic electroluminescence device.
[26] Use of a compound satisfying any one of the following (A) to (C) as a delayed fluorescent material.
(A) A compound having a structure in which two different acceptor groups are bonded to each other.
(B) A compound having a structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked.
(C) A compound having a structure in which two different donor groups are bonded to each other.
[27] A compound represented by the general formula (1).
[28] A compound represented by the general formula (2). However, when n in the general formula (2) is 2, R ¹¹ to R ¹⁸ are hydrogen atoms, R ¹⁹ and R ²⁰ are methyl groups, and D is an unsubstituted dibenzofuran-2,8-diyl group. There is no.

It is a schematic sectional drawing which shows the layer structural example of an organic electroluminescent element. It is a graph which shows the change of the light emission intensity decay curve by the temperature of the co-deposition film | membrane of the compound 1 and PPT. It is a graph which shows the change of the luminescence intensity decay curve by the temperature of the vapor deposition film of compound 9.

Hereinafter, the contents of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. In addition, the isotope species of the hydrogen atom present in the molecule of the compound used in the present invention is not particularly limited. For example, all the hydrogen atoms in the molecule may be ¹ H, or a part or all of the hydrogen atoms are ² H. (Deuterium D) may be used.

[Luminescent Material of the Present Invention]
The luminescent material of the present invention is characterized by comprising a compound that satisfies any of the following conditions (A) to (C).
(A) A compound having a structure in which two different acceptor groups are bonded to each other.
(B) A compound having a structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked.
(C) A compound having a structure in which two different donor groups are bonded to each other.

In the present application, the “acceptor group” means a group whose Hammett σ _p ⁺ value is positive (greater than 0). Further, in the present application, the “donor group” means a group having a Hammett σ _p ⁺ value that is negative (less than 0).
The “Hammett σ _p ⁺ value” in the present invention is L. P. Proposed by Hammett, it quantifies the effect of substituents on the reaction rate or equilibrium of para-substituted benzene derivatives. Specifically, the following formula is established between the substituent in the para-substituted benzene derivative and the reaction rate constant or equilibrium constant:

This is a constant (σ _p ) peculiar to the substituent in. In the above formula, k is a rate constant of a benzene derivative having no substituent, k ₀ is a rate constant of a benzene derivative substituted with a substituent, K is an equilibrium constant of a benzene derivative having no substituent, and K ₀ is a substituent. The equilibrium constant of the benzene derivative substituted with ρ, ρ represents the reaction constant determined by the type and conditions of the reaction. For a description of Hammett's σ _p value and the numerical value of each substituent, refer to JADean edited by “Lange's Handbook of Chemistry 13th edition”, 1985, pages 3-132 to 3-137, McGrow-Hill.

The compound satisfying the above (A) has a structure in which two different acceptor groups are bonded to each other. The two acceptor groups present in the compound satisfying (A) preferably have different acceptor strengths. That is, it is preferable to have a structure in which a relatively strong acceptor group and a relatively weak acceptor group are linked. As a relatively strong acceptor group, for example, an optionally substituted triazine ring group can be exemplified. In addition, examples of the relatively weak acceptor group include an optionally substituted acridone ring group. The relatively strong acceptor group present in the compound satisfying the above (A) and the relatively weak acceptor group preferably have a σp value difference of 0.1 or more, and preferably 0.2 or more. More preferably, for example, a range of 0.3 or more, a range of 0.5 or more, or a range of 0.7 or more may be selected. For example, a range of 1.5 or less and a range of 1.0 or less may be selected. May be. Σp of the relatively weak acceptor group may be selected, for example, from a range of more than 0 to 0.5 or less, may be selected from a range of more than 0 to 0.3 or less, or more than 0 to 0.15 or less You may select from the range.
Each of the two acceptor groups constituting the compound satisfying (A) may contain one or more small substituents. The small substituent that may be contained in each acceptor group may not necessarily be a group that exhibits acceptor properties. That is, as long as each acceptor group exhibits acceptor properties as a whole, the acceptor group may contain a small donor group. Examples of such a donor group include an alkyl group, an alkoxy group, and an aryl group. The alkyl group that can be a small substituent may be linear, branched, or cyclic, but is preferably linear or branched. Further, the number of carbon atoms of the alkyl group may be selected, for example, within the range of 1 to 10, selected from the range of 1 to 6, selected from the range of 1 to 4, or 1 to You may select from the range of 3. The alkoxy group that can be a small substituent may be linear, branched, or cyclic, but is preferably linear or branched. Further, the number of carbon atoms of the alkoxy group may be selected, for example, from the range of 1 to 10, may be selected from the range of 1 to 6, may be selected from the range of 1 to 4, You may select from the range of 3. The aryl group that can be a small substituent may be a single ring or a condensed ring, and the number of carbon atoms may be selected from the range of, for example, 6 to 40, or selected from the range of 6 to 14. It may also be selected from the range of 6-10. It is also preferable that the compound satisfying (A) does not contain any donor group in the molecule.

The compound satisfying the above (B) has a structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked. Have. Examples of such a donor group include a carbazolyl group, and an N-carbazolyl group can be preferably exemplified. Moreover, an acridone ring group can be mentioned as such an acceptor group. For example, the σp value of the donor group may be selected from a range of −0.1 or less, may be selected from a range of −0.2 or less, and may be selected from a range of −0.4 or more. It may also be selected from a range of −0.3 or more. The σp value of the acceptor group may be selected, for example, from a range of 0.1 or more, may be selected from a range of 0.2 or more, or may be selected from a range of 0.4 or less, You may select from the range below 0.3.
The donor group having a Hammett's σp value of −0.5 or more and less than 0 may contain a small acceptor group as long as the entire donor group exhibits a σp value of −0.5 or more and less than 0. . Examples of such an acceptor group include a halogen atom (for example, a fluorine atom). The acceptor group having a Hammett σp value of more than 0 and 0.5 or less may contain a small donor group as long as the entire acceptor group exhibits a σp value of more than 0 and less than 0.5. . For specific examples of such a donor group, the corresponding description in (A) above can be referred to.

The compound satisfying the above (C) has a structure in which two different donor groups are bonded to each other. The two donor groups present in the compound satisfying (C) preferably have different donor properties. That is, it is preferable to have a structure in which a relatively strong donor group and a relatively weak donor group are linked. As a relatively strong donor group, for example, an optionally substituted triazine ring group can be exemplified. Examples of the relatively weak donor group include a dibenzofuran ring group which may be substituted and a dibenzothiophene ring group which may be substituted. The relatively strong donor group present in the compound satisfying the above (C) and the relatively weak donor group preferably have a σp value difference of 0.1 or more, and preferably 0.2 or more. More preferably, for example, a range of 0.3 or more, a range of 0.5 or more, or a range of 0.7 or more may be selected. For example, a range of 1.5 or less or 1.0 or less may be selected. May be. Σp of the relatively weak donor group may be selected from a range of −0.5 or more and less than 0, may be selected from a range of −0.3 or more and less than 0, or −0.15 You may select from the range below 0.
Each of the two donor groups constituting the compound satisfying (C) may each contain one or more small substituents. The small substituent that may be contained in each donor group may not necessarily be a group that exhibits donor properties. That is, as long as each donor group exhibits donor properties as a whole, a small acceptor group may be included in the donor group. Examples of such an acceptor group include a halogen atom (for example, a fluorine atom). It is also preferred that the compound satisfying (C) does not contain any acceptor group in the molecule.

The light-emitting material of the present invention satisfies any of the conditions (A) to (C), and the difference between the lowest excited singlet energy level E _S1 and the lowest excited triplet energy level E _T1 of the compound (ΔE _ST ). Is particularly preferably small. Delta] E _ST may be selected within the range of, for example, 0.6eV or less, preferably less 0.4 eV, more preferably less 0.3 eV, and more preferably less 0.2 eV. If particular structures of compounds, approximate values of Delta] E _ST is can be determined by calculation. For example, it can be calculated using a calculation method by Gaussian et al. Therefore, it is possible to refine the structure of a compound having a (A) ~ designing the structure of any of satisfying compound of component (C), by performing the calculation for the structure, a small Delta] E _ST. Therefore, a desirable compound can be specifically found based on the concept provided by the present invention.

ΔE _ST here is obtained by calculating the difference between the lowest excited singlet energy level (E _S1 ) and the lowest excited triplet energy level (E _T1 ) from the emission ends of the fluorescence and phosphorescence spectra. . Specifically, by implementing the following method can be determined easily Delta] E _ST.
(1) Lowest excited singlet energy level (E _S1 )
A toluene solution (concentration: 1 × 10 ⁻⁵ M) containing a measurement target compound or a PMMA film (compound concentration: 0.1 mol%, thickness 100 nm) containing a measurement target compound formed on a silicon substrate is used as a measurement sample. Prepared and measured the fluorescence spectrum of this sample at room temperature (300K). Specifically, by integrating the luminescence from immediately after the excitation light was incident to 100 nanoseconds after the incident, a fluorescence spectrum having the emission intensity on the vertical axis and the wavelength on the horizontal axis was obtained. A tangent line was drawn to the rising edge of the emission spectrum on the short wavelength side, and the wavelength value λ edge [nm] at the intersection of the tangent line and the horizontal axis was obtained. A value obtained by converting this wavelength value into an energy value by the following conversion formula was defined as _ES1 .
Conversion formula: E _S1 [eV] = 1239.85 / λedge
(2) Lowest excited triplet energy level (E _T1 )
The same sample as the lowest excitation singlet energy level (E _S1 ) was cooled to 5 [K], the excitation light (337 nm) was irradiated onto the phosphorescence measurement sample, and the phosphorescence intensity was measured using a streak camera. By integrating the luminescence from 1 millisecond after the excitation light incidence to 10 milliseconds after the incidence, a phosphorescence spectrum having the luminescence intensity on the vertical axis and the wavelength on the horizontal axis was obtained. A tangent line was drawn with respect to the rising edge of the phosphorescence spectrum on the short wavelength side, and a wavelength value λ edge [nm] at the intersection of the tangent line and the horizontal axis was obtained. A value obtained by converting this wavelength value into an energy value by the following conversion formula was defined as _ET1 .
Conversion formula: E _T1 [eV] = 1239.85 / λedge
The tangent to the short wavelength rising edge of the phosphorescence spectrum was drawn as follows. When moving on the spectrum curve from the short wavelength side of the phosphorescence spectrum to the maximum value on the shortest wavelength side of the maximum value of the spectrum, the tangent at each point on the curve toward the long wavelength side was considered. The slope of this tangent line increases as the curve rises (that is, as the vertical axis increases). The tangent drawn at the point where the value of the slope takes the maximum value was taken as the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side.
The maximum point having a peak intensity of 10% or less of the maximum peak intensity of the spectrum is not included in the maximum value on the shortest wavelength side described above, and the slope value closest to the maximum value on the shortest wavelength side is the maximum value. The tangent drawn at the point taken was taken as the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side.
In addition, when a sample is a toluene solution, it measures with a phosphorescence measuring apparatus at 77 [K].

According to the present invention, in a compound having a structure, for example two donor group structurally different and each other to two different acceptor group bonded to each other bound, to separate the HOMO and LUMO, a molecule having a smaller Delta] E _ST design Is possible. Since such a compound can be a molecule having a larger band gap than the conventional thermally activated delayed fluorescent material, various blue light emitting materials can be developed according to the present invention. Further, the conventional thermally activated delayed fluorescent material has a structure in which a donor group and an acceptor group are bonded, and a group that stabilizes a radical cation is selected as an electron donor group, and a radical is selected as an acceptor group. A group that stabilizes the anion is selected. Since such a donor-acceptor-coupled thermally activated delayed fluorescent material generates a stable charge separation state, the lifetime of the delayed fluorescent component is relatively long, on the order of microseconds to milliseconds. This means that the lifetime as a T ₁ exciton is long. When the luminescent molecule in the T ₁ excited state comes into contact with the oxygen molecule, the exciton energy of the luminescent molecule moves to the oxygen molecule by the Dexter mechanism, and the excitons on the luminescent molecule disappear. For this reason, T ₁ excitons capable of intersystem crossing to S ₁ are decreased, and the emission quantum yield of the TADF molecule is decreased in the presence of oxygen. In particular, according to the luminescent material of the present invention that satisfies the condition (A) or (C), the ability to stabilize one of the radical anion or the radical cation is deficient. _The path from ₁ to the ground state through the reverse intersystem crossing is promoted, and the lifetime of the T ₁ exciton is shortened so that it is less susceptible to the quenching by oxygen.

[Compound represented by general formula (1)]
The compound having the structure represented by the general formula (1) preferably used for the light emitting material of the present invention will be described.
In the general formula (1), Z represents an electron withdrawing group. The term “electron withdrawing group” as used herein means a group having a stronger property of attracting electrons than a methylene group. As an electron-withdrawing group that can be preferably used as Z,>C═O,> C═C (CN) ₂ ,> BR ¹⁰ ,> SO ₂ ,> C (CF ₃ ) ₂ ,> P (= O) R ¹¹ and S can be mentioned, but the electron-withdrawing group that can be employed in the present invention is not limited to these examples. Here, R ¹⁰ and R ¹¹ represent a substituent. The preferred substituents that R ¹⁰ and R ¹¹ can take are a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, and more preferably those having 1 to 10 carbon atoms. A substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, a substituted or unsubstituted heteroaryl group having 5 to 18 carbon atoms, and more preferably a substituted or unsubstituted aryl group having 6 to 18 carbon atoms. An unsubstituted aryl group.
Since the structural portion excluding R ⁹ in the general formula (1) has an electron-withdrawing group corresponding to Z together with a nitrogen atom connecting two benzene rings, it has both a donor property and an acceptor property. It has a characteristic structural part.

In the general formula (1), R ¹ to R ⁸ each independently represents a hydrogen atom or a substituent. R ⁹ represents a substituent. Examples of the substituent that R ¹ to R ⁹ can take include, for example, a hydroxy group, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, An alkyl-substituted amino group having 1 to 20 carbon atoms, an aryl-substituted amino group having 12 to 40 carbon atoms, an acyl group having 2 to 20 carbon atoms, an aryl group having 6 to 40 carbon atoms, a heteroaryl group having 3 to 40 carbon atoms, Substituted or unsubstituted carbazolyl group having 12 to 40 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkynyl group having 2 to 10 carbon atoms, alkoxycarbonyl group having 2 to 10 carbon atoms, alkylsulfonyl having 1 to 10 carbon atoms Group, haloalkyl group having 1 to 10 carbon atoms, amide group, alkylamide group having 2 to 10 carbon atoms, trialkylsilyl group having 3 to 20 carbon atoms, tria having 4 to 20 carbon atoms Kill silylalkyl group, trialkylsilyl alkenyl group having 5 to 20 carbon atoms, and the like trialkylsilyl alkynyl group and a nitro group having 5 to 20 carbon atoms. Among these specific examples, those that can be substituted with a substituent may be further substituted. More preferred substituents are a halogen atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms, carbon A substituted or unsubstituted heteroaryl group having 3 to 40 carbon atoms, a substituted or unsubstituted dialkylamino group having 1 to 10 carbon atoms, a substituted or unsubstituted diarylamino group having 12 to 40 carbon atoms, and 12 to 40 carbon atoms A substituted or unsubstituted carbazolyl group; More preferred substituents are a fluorine atom, a chlorine atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, and a substituted group having 1 to 10 carbon atoms. Or an unsubstituted dialkylamino group, a substituted or unsubstituted diarylamino group having 12 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 15 carbon atoms, and a substituted or unsubstituted heteroaryl group having 3 to 12 carbon atoms It is a group. R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , R ⁷ and R ⁸ , R ⁴ and R ⁹ , R ⁵ and R ⁹ are respectively They may be bonded to each other to form a cyclic structure.

At least one of R ¹ to R ⁹ is a donor group or an acceptor group. The condition (A) or (B) is selected.

In a preferred embodiment of the present invention, it is desirable to select a donor group as R ¹ of the compound represented by the general formula (1). As the donor group, a substituted or unsubstituted heteroaryl group or a substituted or unsubstituted aryl group can be preferably employed, and a substituted or unsubstituted heteroaryl group can be more preferably employed. Examples of the substituted or unsubstituted heteroaryl group include a substituted or unsubstituted carbazolyl group. When R ¹ is a donor group, R ⁹ is preferably a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, and more preferably a substituted or unsubstituted aryl group. .

In another preferred embodiment of the present invention, it is also preferable to select an acceptor group as R ⁹ of the compound represented by the general formula (1). Examples of the acceptor group include a substituted or unsubstituted triazinyl group. Of these, a diaryltriazinyl group can be preferably employed.
As described above, the basic skeleton of the general formula (1) exhibits characteristics useful as a light emitting material both when it is substituted with a donor group and when it is substituted with an acceptor group.

[Synthesis Method of Compound Represented by General Formula (1)]
The method for synthesizing the compound represented by the general formula (1) is not particularly limited. For example, it can be synthesized by R ⁹ in the general formula (1) reacting a compound represented by the compound R ^9-X is a hydrogen atom. Here, X is a halogen atom, preferably a chlorine atom, a bromine atom or an iodine atom. The compound represented by the general formula (1) can also be synthesized by combining other known synthesis reactions.

[Compound represented by formula (2)]
The compound having the structure represented by the general formula (2) preferably used for the light emitting material of the present invention will be described.
In General formula (2), D represents the dibenzofuran ring group which may be substituted, or the dibenzothiophene ring group which may be substituted. R ¹¹ to R ²⁰ each independently represents a hydrogen atom or a substituent. R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁷ , R ¹⁷ and R ¹⁸ , R ¹⁸ and R ¹⁹ , R ¹⁹ and R ²⁰ , R ²⁰ And R ¹¹ may be bonded to each other to form a cyclic structure. n represents an integer of 1 to 4. However, general formula (2) satisfies the condition of (C).
The dibenzofuran ring or dibenzothiophene ring constituting D may be substituted with a donor group, may be substituted with an acceptor group, or may be unsubstituted. In any case, the substitution mode of the dibenzofuran ring or dibenzothiophene ring is not limited as long as D can be a donor group as a whole. The substituent which R ¹¹ to R ²⁰ can take may be a donor group or an acceptor group. As long as the structural part excluding D exhibits donor properties as a whole, the type of these substituents is not limited. For the substituents that can be employed in the general formula (2) and preferred ranges, the description of the substituents that can be taken by R ¹ to R ^{8 in} the general formula (1) can be referred to.
R ¹⁹ and R ²⁰ in the general formula (2) may be the same or different, but are preferably the same. R ¹⁹ and R ²⁰ are preferably an alkyl group, for example, preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms.
N in the general formula (2) is an integer of 1 to 4, and is preferably 1 or 2.
D in the general formula (2) may be bonded at any position of the dibenzofuran ring or the dibenzothiophene ring. When n is 2, it is preferably bonded to any one of the 1 to 4 positions of the dibenzofuran ring or the dibenzothiophene ring and any one of the 6 to 9 positions. For example, a mode of bonding at the 2-position and the 8-position, a mode of bonding at the 3-position and the 7-position, and a mode of bonding at the 4-position and the 6-position can be exemplified. Among them, it is particularly preferable to bond at the 4-position and the 6-position (see Compound 9).

[Synthesis Method of Compound Represented by General Formula (2)]
A method for synthesizing the compound represented by the general formula (2) is not particularly limited. For example, it can be synthesized by reacting a compound represented by DX with a compound in which D in the general formula (2) is a hydrogen atom. Here, X is a halogen atom, preferably a chlorine atom, a bromine atom or an iodine atom. The compound represented by the general formula (1) can also be synthesized by combining other known synthesis reactions.

[Specific examples and variations of compounds]
Below, the specific example of a compound represented by General formula (1) or General formula (2) is given. However, the compounds that can be used in the present invention are not limitedly interpreted by these exemplified compounds.

The compound represented by the general formula (1) or the general formula (2) can emit delayed fluorescence. Therefore, the present invention includes an invention of a delayed phosphor having a structure represented by the general formula (1) or the general formula (2).

The molecular weight of the compound represented by the general formula (1) or the general formula (2) is used by, for example, forming an organic layer containing the compound represented by the general formula (1) or the general formula (2) by vapor deposition. When it is intended to do, it is preferably 1500 or less, more preferably 1200 or less, even more preferably 1000 or less, and even more preferably 800 or less. The lower limit of the molecular weight is the smallest molecular weight that the general formula (1) or the general formula (2) can take.
The compound represented by the general formula (1) or the general formula (2) may be formed by a coating method regardless of the molecular weight. If a coating method is used, a film can be formed even with a compound having a relatively large molecular weight.

Further, the compound that emits delayed fluorescence and is capable of intramolecular proton transfer may be a polymer obtained by polymerizing a polymerizable monomer that emits delayed fluorescence and is capable of intramolecular proton transfer.
For example, a polymer obtained by preliminarily allowing a polymerizable group to exist in the structure represented by the general formula (1) or (2) and polymerizing the polymerizable group is used for the organic light emitting device. It can be considered to be used as a material. Specifically, a monomer containing a polymerizable functional group in any of R ¹ to R ^{9 in} the general formula (1), R ¹¹ to R ^{20 in} the general formula (2), or D is prepared. It is conceivable that a polymer having a repeating unit is obtained by polymerizing the polymer alone or with other monomers, and the polymer is used as a material for the organic light-emitting device. Alternatively, by diluting the compounds having the structure represented by the general formula (1) or by coupling the compounds having the structure represented by the general formula (2), It is also conceivable to obtain a monomer and use them as a material for the organic light emitting device.

Examples of a polymer having a repeating unit containing a structure represented by the general formula (1) or (2) include a polymer containing a structure represented by the following general formula (11) or (12) Can do.

In General Formula (11) or (12), Q represents a group including a structure represented by General Formula (1) or General Formula (2), and L ¹ and L ² represent a linking group. The linking group preferably has 0 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and still more preferably 2 to 10 carbon atoms. And preferably has a structure represented by - linking group ^-X 11 ^{-L 11.} Here, X ¹¹ represents an oxygen atom or a sulfur atom, and is preferably an oxygen atom. L ¹¹ represents a linking group, and is preferably a substituted or unsubstituted alkylene group, or a substituted or unsubstituted arylene group, and is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms, or a substituted or unsubstituted group A phenylene group is more preferable.
In General Formula (11) or (12), R ¹⁰¹ , R ¹⁰² , R ¹⁰³ and R ¹⁰⁴ each independently represent a substituent. Preferably, it is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, or a halogen atom, more preferably an unsubstituted alkyl group having 1 to 3 carbon atoms. An unsubstituted alkoxy group having 1 to 3 carbon atoms, a fluorine atom, and a chlorine atom, and more preferably an unsubstituted alkyl group having 1 to 3 carbon atoms and an unsubstituted alkoxy group having 1 to 3 carbon atoms.
The linking group represented by L ¹ and L ² is any ^one of R ¹ to R ^{9 having} the structure of the general formula (1) constituting Q, R ¹¹ to R ^{20 having} the structure of the general formula (2), and D Can be bound to either. Two or more linking groups may be linked to one Q to form a crosslinked structure or a network structure.

Specific examples of the structure of the repeating unit include structures represented by the following formulas (13) to (16).

The polymer having a repeating unit containing the formulas (13) to (16) is any ^one of R ¹ to R ⁹ having the structure of the general formula (1), or R ¹¹ to R ^{20 having} the structure of the general formula (2). It can be synthesized by introducing a hydroxy group into any of D and D, reacting the following compound as a linker to introduce a polymerizable group, and polymerizing the polymerizable group.

The polymer containing the structure represented by the general formula (1) or the general formula (2) in the molecule is a polymer composed only of repeating units having the structure represented by the general formula (1) or the general formula (2). It may be a polymer containing a repeating unit having other structure. In addition, the repeating unit having a structure represented by the general formula (1) or the general formula (2) contained in the polymer may be a single type or two or more types. Examples of the repeating unit not having the structure represented by the general formula (1) or the general formula (2) include those derived from monomers used in ordinary copolymerization. Examples thereof include a repeating unit derived from a monomer having an ethylenically unsaturated bond such as ethylene and styrene.

[Organic light emitting device]
In the organic light emitting device of the present invention, a compound that emits delayed fluorescence and is capable of intramolecular proton transfer is used. A compound that emits delayed fluorescence and is capable of intramolecular proton transfer exhibits a sufficiently high quantum yield for practical use, and can be effectively used as a light-emitting material of an organic light-emitting device. Further, a compound that emits delayed fluorescence and is capable of intramolecular proton transfer can also be used as a host or assist dopant in an organic light-emitting device. For example, an organic light-emitting device using a compound that emits delayed fluorescence and is capable of intramolecular proton transfer as a light-emitting material has a feature of high luminous efficiency because this compound functions as a delayed fluorescent material. The principle will be described below by taking an organic electroluminescence element as an example.

In the organic electroluminescence element, carriers are injected into the light emitting material from both positive and negative electrodes to generate an excited light emitting material and emit light. In general, in the case of a carrier injection type organic electroluminescence element, 25% of the generated excitons are excited to the excited singlet state, and the remaining 75% are excited to the excited triplet state. Therefore, the use efficiency of energy is higher when phosphorescence, which is light emission from an excited triplet state, is used. However, since the excited triplet state has a long lifetime, energy saturation occurs due to saturation of the excited state and interaction with excitons in the excited triplet state, and in general, the quantum yield of phosphorescence is often not high. On the other hand, delayed fluorescent materials, after energy transition to an excited triplet state due to intersystem crossing, etc., are then crossed back to an excited singlet state due to triplet-triplet annihilation or absorption of thermal energy, and emit fluorescence. To do. In the organic electroluminescence device, it is considered that a thermally activated delayed fluorescent material by absorption of thermal energy is particularly useful. When a delayed fluorescent material is used for the organic electroluminescence element, excitons in the excited singlet state emit fluorescence as usual. On the other hand, excitons in the excited triplet state absorb the heat of the outside air and the heat generated by the device, and cross the terms into the excited singlet to emit fluorescence. At this time, since the light is emitted from the excited singlet, the light is emitted at the same wavelength as the fluorescence, but the light lifetime (luminescence lifetime) generated by the reverse intersystem crossing from the excited triplet state to the excited singlet state is normal. Since the fluorescence becomes longer than the fluorescence and phosphorescence, it is observed as fluorescence delayed from these. This can be defined as delayed fluorescence. If such a heat-activated exciton transfer mechanism is used, the ratio of the compound in an excited singlet state, which normally generated only 25%, is increased to 25% or more by absorbing thermal energy after carrier injection. It can be raised. If a compound that emits strong fluorescence and delayed fluorescence even at a low temperature of less than 100 ° C is used, the heat of the device will sufficiently cause intersystem crossing from the excited triplet state to the excited singlet state and emit delayed fluorescence. Efficiency can be improved dramatically.

By using a compound that emits delayed fluorescence and allows intramolecular proton transfer as the light emitting material of the light emitting layer, excellent organic light emission such as organic photoluminescence device (organic PL device) and organic electroluminescence device (organic EL device) An element can be provided. The organic photoluminescence element has a structure in which at least a light emitting layer is formed on a substrate. The organic electroluminescence element has a structure in which at least an anode, a cathode, and an organic layer are formed between the anode and the cathode. The organic layer includes at least a light emitting layer, and may consist of only the light emitting layer, or may have one or more organic layers in addition to the light emitting layer. Examples of such other organic layers include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an exciton blocking layer. The hole transport layer may be a hole injection / transport layer having a hole injection function, and the electron transport layer may be an electron injection / transport layer having an electron injection function. A specific example of the structure of an organic electroluminescence element is shown in FIG. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer, 6 is an electron transport layer, and 7 is a cathode.
Below, each member and each layer of an organic electroluminescent element are demonstrated. In addition, description of a board | substrate and a light emitting layer corresponds also to the board | substrate and light emitting layer of an organic photo-luminescence element.

(substrate)
The organic electroluminescence device of the present invention is preferably supported on a substrate. The substrate is not particularly limited and may be any substrate conventionally used for organic electroluminescence elements. For example, a substrate made of glass, transparent plastic, quartz, silicon, or the like can be used.

(anode)
As the anode in the organic electroluminescence element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, a thin film may be formed by vapor deposition or sputtering of these electrode materials, and a pattern of a desired shape may be formed by photolithography, or when pattern accuracy is not so high (about 100 μm or more) ), A pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. Or when using the material which can be apply | coated like an organic electroconductivity compound, wet film-forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

(cathode)
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is 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 ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, Magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic electroluminescence element is transparent or translucent, the emission luminance is advantageously improved.
In addition, by using the conductive transparent material mentioned in the description of the anode as a cathode, a transparent or semi-transparent cathode can be produced. By applying this, an element in which both the anode and the cathode are transparent is used. Can be produced.

(Light emitting layer)
The light emitting layer is a layer that emits light after excitons are generated by recombination of holes and electrons injected from each of the anode and the cathode, and the light emitting material may be used alone for the light emitting layer. , Preferably including a luminescent material and a host material. As the luminescent material, one or more selected from a group of compounds that emit delayed fluorescence and are capable of intramolecular proton transfer can be used. In order for the organic electroluminescent device and the organic photoluminescent device of the present invention to exhibit high luminous efficiency, it is important to confine singlet excitons and triplet excitons generated in the light emitting material in the light emitting material. Therefore, it is preferable to use a host material in addition to the light emitting material in the light emitting layer. As the host material, an organic compound in which at least one of excited singlet energy and excited triplet energy has a value higher than that of the light-emitting material can be used. As a result, singlet excitons and triplet excitons generated in the light emitting material can be confined in the molecule of the light emitting material, and the light emission efficiency can be sufficiently extracted. However, even if singlet excitons and triplet excitons cannot be sufficiently confined, there are cases where high luminous efficiency can be obtained, so that host materials that can achieve high luminous efficiency are particularly limited. And can be used in the present invention. In the organic light-emitting device or organic electroluminescence device of the present invention, light emission is generated from a light-emitting material (compound that emits delayed fluorescence and is capable of intramolecular proton transfer) contained in the light-emitting layer. This emission includes both fluorescence and delayed fluorescence. However, light emission from the host material may be partly or partly emitted.
When a host material is used, the amount of a compound that is a light emitting material, that is, a compound that emits delayed fluorescence and capable of intramolecular proton transfer is preferably 0.1% by weight or more. It is more preferably at least wt%, more preferably at most 50 wt%, more preferably at most 20 wt%, and even more preferably at most 10 wt%.
The host material in the light-emitting layer is preferably an organic compound that has a hole transporting ability and an electron transporting ability, prevents the emission of longer wavelengths, and has a high glass transition temperature.

(Injection layer)
The injection layer is a layer provided between the electrode and the organic layer for lowering the driving voltage and improving the luminance of light emission. There are a hole injection layer and an electron injection layer, and between the anode and the light emitting layer or the hole transport layer. Further, it may be present between the cathode and the light emitting layer or the electron transport layer. The injection layer can be provided as necessary.

(Blocking layer)
The blocking layer is a layer that can prevent diffusion of charges (electrons or holes) and / or excitons existing in the light emitting layer to the outside of the light emitting layer. The electron blocking layer can be disposed between the light emitting layer and the hole transport layer and blocks electrons from passing through the light emitting layer toward the hole transport layer. Similarly, a hole blocking layer can be disposed between the light emitting layer and the electron transporting layer to prevent holes from passing through the light emitting layer toward the electron transporting layer. The blocking layer can also be used to block excitons from diffusing outside the light emitting layer. That is, each of the electron blocking layer and the hole blocking layer can also function as an exciton blocking layer. The term “electron blocking layer” or “exciton blocking layer” as used herein is used in the sense of including a layer having the functions of an electron blocking layer and an exciton blocking layer in one layer.

(Hole blocking layer)
The hole blocking layer has a function of an electron transport layer in a broad sense. The hole blocking layer has a role of blocking holes from reaching the electron transport layer while transporting electrons, thereby improving the recombination probability of electrons and holes in the light emitting layer. As the material for the hole blocking layer, the material for the electron transport layer described later can be used as necessary.

(Electron blocking layer)
The electron blocking layer has a function of transporting holes in a broad sense. The electron blocking layer has a role to block electrons from reaching the hole transport layer while transporting holes, thereby improving the probability of recombination of electrons and holes in the light emitting layer. .

(Exciton blocking layer)
The exciton blocking layer is a layer for preventing excitons generated by recombination of holes and electrons in the light emitting layer from diffusing into the charge transport layer. It becomes possible to efficiently confine in the light emitting layer, and the light emission efficiency of the device can be improved. The exciton blocking layer can be inserted on either the anode side or the cathode side adjacent to the light emitting layer, or both can be inserted simultaneously. That is, when the exciton blocking layer is provided on the anode side, the layer can be inserted adjacent to the light emitting layer between the hole transport layer and the light emitting layer, and when inserted on the cathode side, the light emitting layer and the cathode Between the luminescent layer and the light-emitting layer. Further, a hole injection layer, an electron blocking layer, or the like can be provided between the anode and the exciton blocking layer adjacent to the anode side of the light emitting layer, and the excitation adjacent to the cathode and the cathode side of the light emitting layer can be provided. Between the child blocking layer, an electron injection layer, an electron transport layer, a hole blocking layer, and the like can be provided. When the blocking layer is disposed, at least one of the excited singlet energy and the excited triplet energy of the material used as the blocking layer is preferably higher than the excited singlet energy and the excited triplet energy of the light emitting material.

(Hole transport layer)
The hole transport layer is made of a hole transport material having a function of transporting holes, and the hole transport layer can be provided as a single layer or a plurality of layers.
The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. Known hole transport materials that can be used include, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indolocarbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, Examples include amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. An aromatic tertiary amine compound and an styrylamine compound are preferably used, and an aromatic tertiary amine compound is more preferably used.

(Electron transport layer)
The electron transport layer is made of a material having a function of transporting electrons, and the electron transport layer can be provided as a single layer or a plurality of layers.
The electron transport material (which may also serve as a hole blocking material) may have a function of transmitting electrons injected from the cathode to the light emitting layer. Examples of the electron transport layer that can be used include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide oxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

When producing an organic electroluminescence device, not only a compound that emits delayed fluorescence and capable of intramolecular proton transfer may be used for a light emitting layer, but also for a layer other than the light emitting layer. At that time, the compound that emits delayed fluorescence contained in each layer and is capable of intramolecular proton transfer may be the same or different depending on whether it is used for the light-emitting layer or a layer other than the light-emitting layer. Good. For example, the above injection layer, blocking layer, hole blocking layer, electron blocking layer, exciton blocking layer, hole transport layer, electron transport layer, etc. can emit delayed fluorescence and allow intramolecular proton transfer May be used. The method for forming these layers is not particularly limited, and the layer may be formed by either a dry process or a wet process.

Specific examples of preferable materials that can be used for the organic electroluminescence element are shown below. However, the material that can be used in the present invention is not limited to the following exemplary compounds. Moreover, even if it is a compound illustrated as a material which has a specific function, it can also be diverted as a material which has another function.

First, preferred compounds that can also be used as a host material for the light emitting layer are listed.

Next, preferred examples of compounds that can be used as the hole injection material are given.

Next, preferred examples of compounds that can be used as a hole transport material are given.

Next, preferred examples of compounds that can be used as an electron blocking material are given.

Next, preferred examples of compounds that can be used as hole blocking materials are given.

Next, preferred compound examples that can be used as an electron transporting material are listed.

Next, preferred examples of compounds that can be used as an electron injection material will be given.

Further preferred compound examples are given as materials that can be added. For example, adding as a stabilizing material can be considered.

The organic electroluminescent device produced by the above-described method emits light by applying an electric field between the anode and the cathode of the obtained device. At this time, if the light is emitted by excited singlet energy, light having a wavelength corresponding to the energy level is confirmed as fluorescence emission and delayed fluorescence emission. In addition, in the case of light emission by excited triplet energy, a wavelength corresponding to the energy level is confirmed as phosphorescence. Since normal fluorescence has a shorter fluorescence lifetime than delayed fluorescence, the emission lifetime can be distinguished from fluorescence and delayed fluorescence.
On the other hand, phosphorescence is hardly observable at room temperature in ordinary organic compounds such as the compounds of the present invention because the excited triplet energy is unstable and converted to heat, etc., and has a short lifetime and immediately deactivates. In order to measure the excited triplet energy of a normal organic compound, it can be measured by observing light emission under extremely low temperature conditions.

The organic electroluminescence element of the present invention can be applied to any of a single element, an element having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix. According to the present invention, an organic light-emitting device having greatly improved light emission efficiency can be obtained by including in the light-emitting layer a compound that emits delayed fluorescence and allows intramolecular proton transfer. The organic light emitting device such as the organic electroluminescence device of the present invention can be further applied to various uses. For example, it is possible to produce an organic electroluminescence display device using the organic electroluminescence element of the present invention. For details, see “Organic EL Display” (Ohm Co., Ltd.) written by Shizushi Tokito, Chiba Adachi and Hideyuki Murata. ) Can be referred to. In particular, the organic electroluminescence device of the present invention can be applied to organic electroluminescence illumination and backlights that are in great demand.

The organic light emitting device of the present invention may be an organic light emitting transistor. An organic light emitting transistor has a structure in which, for example, a gate electrode is stacked on an active layer that also serves as a light emitting layer via a gate insulating layer, and a source electrode and a drain electrode are connected to the active layer. By using a compound capable of emitting delayed fluorescence and capable of intramolecular proton transfer in the active layer of such an organic light-emitting transistor, an organic light-emitting transistor excellent in both carrier mobility and light emission characteristics can be realized.

Hereinafter, the features of the present invention will be described more specifically with reference to synthesis examples and examples. The following materials, processing details, processing procedures, and the like can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Synthesis Example 1 Synthesis of Compound 1

2-Bromo-4,6-diphenyltriazine (1.56 g, 5.0 mmol), 9-acridone (1.17 g, 6.0 mmol), tetrafluoroboric acid-tri-t-butylphosphine (0.085 g, 0.8 mmol). 30 mmol), sodium-t-butoxide (0.575 g, 6.0 mmol), tris (dibenzylideneacetone) -dipalladium (0.090 g, 0.10 mmol), dehydrated toluene (60 mL) in a three-necked flask under a nitrogen atmosphere. And stirred at 120 ° C. overnight. The reaction solution was returned to room temperature, washed with pure water and separated. The separated organic layer was dried over magnesium sulfate and then reprecipitated with ethanol to obtain 1.18 g of Compound 1 as a white solid in a yield of 56%.
¹ HNMR (500 MHz, CDCl 3): δ 8.71 (td, J = 2.0, 8.5 Hz, 4H, e), 8.61 (dd, J = 1.5, 8.0 Hz, 2H, a), 7.67 (tt, J = 2.0, 7.5 Hz, 2H, c), 7.58 (tt, J = 1.5, 4.5 Hz, 4H, f), 7.56 (dd, J = 2.0, 7.0 Hz, 2H, g), 7.36 (dt, J = 1.0, 7.5 Hz, 2H, b), 7.07 (d, J = 4.5 Hz, 2H, d)
MS (ASAP) m / z 427.14 [MH ^<+ >].

Synthesis Example 2 Synthesis of Compound 2

3-Bromophenylcarbazole (1.61 g, 5 mmol), potassium carbonate (1.38 g, 10 mmol), powdered copper (0.0636 g, 1 mmol), methyl anthranilate (30.2 g, 500 mmol) were placed in a two-necked flask, The mixture was stirred at 140 ° C. for 72 hours. After returning the reaction solution to room temperature and washing with pure water, the organic layer was dried over magnesium sulfate and distilled under reduced pressure. The remaining solid was purified by column chromatography (silica gel, dichloromethane: hexane = 1: 2), Intermediate 1 was obtained in a yield of 1.30 g and a yield of 67% as a pale yellow solid.
¹ HNMR (500 MHz, CDCl ₃ ): δ 9.65 (s, 1H), 8.13 (d, J = 7.5 Hz, 2H), 7.97 (d, J = 7.5 Hz, 1H), 7. 53 (t, J = 7.5 Hz, 1H), 7.43 (m, 6H), 7.29 (m, 5H), 6.76 (t, J = 7.5 Hz, 1H), 3.90 ( s, 3H)
MS (ASAP) m / z 392.15 [M ^<+ >].

Intermediate 1 (1.30 g, 3.32 mmol) was dissolved in 50 mL of THF, and 20 mL of ethanol and 50 mL of aqueous sodium hydroxide solution (0.5 M) were added and stirred at room temperature for 20 hours. The solvent was removed from the reaction solution using an evaporator, 200 mL of pure water was added to the residue, and the mixture was heated to 90 ° C. and dissolved. Hydrochloric acid was added to this solution until the pH reached 1, and the white precipitate was collected by filtration to obtain Intermediate 2 in a yield of 1.21 g and a yield of 97%.
¹ HNMR (500 MHz, CDCl ₃ ): δ 9.50 (s, 1H), 8.15 (d, J = 7.5 Hz, 2H), 8.04 (d, J = 8.0 Hz, 1H), 7. 57 (t, J = 8.0 Hz, 1H), 7.47 (m, 3H), 7.43 (dt, J = 1.5, 7.0 Hz, 2H), 7.39 (dd, J = 1) 0.0, 4.0 Hz, 2H), 7.35 (m, 1H), 7.30 (m, 3H), 6.80 (m, 1H)
MS (ASAP) m / z 378.12 [M ^<+ >].

A two-necked flask containing Intermediate 2 (1.21 g, 3.22 mmol) and polyphosphoric acid (3.10 g, 32.0 mmol) was stirred at 90 ° C. overnight. The reaction product was poured and dissolved in 300 mL of pure water, and ammonia water was added until the solution became basic. The obtained solid was purified by column chromatography (silica gel, dichloromethane: hexane = 1: 2) to obtain Intermediate 3 in a yield of 0.105 g and a yield of 9% as a pale green solid.
¹ HNMR (500 MHz, CDCl ₃ ): δ 8.55 (dd, J = 1.5, 7.5 Hz, 1H), 8.31 (dd, J = 1.5, 7.5 Hz, 1H), 8.27 (Dd, J = 1.5, 7.5 Hz, 1H), 8.19 (dd, J = 1.5, 7.5 Hz, 1H), 7.94 (dd, J = 1.5, 7.5 Hz) , 1H), 7.70 (dd, J = 1.5, 7.5 Hz, 1H), 7.59 (m, 2H), 7.50 (dt, J = 1.5, 7.5 Hz, 1H) 7.35 (dt, J = 1.5, 7.5 Hz, 1H), 7.18 (m, 3H), 6.95 (dd, J = 1.5, 7.5 Hz, 1H)
MS (ASAP) m / z 360.13 [M ^<+ >].

Intermediate 3 (0.105 g, 0.290 mmol), potassium carbonate (80.0 mg, 0.580 mmol) and powdered copper (3.71 mg, 0.0580 mmol) were dissolved in bromobenzene and heated at 140 ° C. overnight. The reaction solution was returned to room temperature, washed pure and separated, and the organic layer was purified by column chromatography (silica gel, chloroform), and a reddish brown solid compound 2 with m / z = 436.16 was obtained by mass spectrometry. .
MS (ASAP) m / z 436.16 [M ^<+ >].

Synthesis Example 3 Synthesis of Compound 3

9,9-dimethylacridan (0.42 g, 2 mmol), 1-bromodibenzofuran (0.24 g, 1 mmol), tetrafluoroborate-tri-t-butylphosphine (35 mg, 0.12 mmol), sodium-t- Butoxide (0.23 g, 2.4 mmol) and tris (dibenzylideneacetone) dibaradium (0) (37 mg, 0.04 mmol) were placed in a three-necked flask, dehydrated toluene (40 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by thin layer chromatography (TLC), the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified using column chromatography (silica gel, chloroform: hexane = 1: 6) to obtain 0.23 g of white powder of Compound 3 in a yield of 60%.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 7.96 (d, J = 8.0 Hz, 1H, l), 7.83 (t, J = 8.0 Hz, 1H, j), 7.74 (d , J = 8.0 Hz, 1H, i), 7.59 (d, J = 7.0 Hz, 2H, e), 7.45 (t, J = 7.5 Hz, 1H, g), 7.40 ( d, J = 7.5 Hz, 1H, h), 7.11 (t, J = 7.5 Hz, 1H, k), 7.07 (d, J = 7.5 Hz, 1H, f), 6.90. (T, J = 7.5 Hz, 2H, d), 6.84 (t, J = 7.0 Hz, 2H, c), 6.02 (d, J = 8.0 Hz, 2H, b), 1. 77 (d, 6H, a)
MS (ASAP) m / z 376.15 [MH ⁺ ]

(Synthesis Example 4) Synthesis of Compound 4

9,9-dimethylacridan (0.71 g, 3.4 mmol), 2-bromodibenzofuran (1.0 g, 4 mmol), tetrafluoroboric acid-tri-t-butylphosphine (70 mg, 0.24 mmol), sodium- t-Butoxide (0.46 g, 4.8 mmol) and tris (dibenzylideneacetone) dibaladium (0) (73 mg, 0.08 mmol) were placed in a three-necked flask, dehydrated toluene (40 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified by column chromatography (silica gel, dichloromethane: hexane = 6: 1) to obtain white powder of Compound 4 in a yield of 1.2 g and a yield of 90%.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 8.25 (ds, J = 2.0 Hz, 1H, l), 8.21 (d, J = 7.5 Hz, 1H, g), 7.80 (d , J = 8.5 Hz, 1H, k), 7.59 (dt, J = 1.5, 7.0 Hz, 1H, i), 7.52 (dd, J = 1.5, 7.5 Hz, 2H) E), 7.48 (dd, J = 2.0, 8.5 Hz, 1H, h), 7.43 (dt, J = 0.5, 7.5 Hz, 1H, j), 6.96 ( dt, J = 1.5, 7.0 Hz, 2H, d), 6.91 (dt, J = 1.5, 7.0 Hz, 2H, c), 6.19 (dd, J = 1.0, 8.0 Hz, 2H, b), 1.67 (s, 6H, a)
MS (ASAP) m / z 376.32 [MH ⁺ ]

Synthesis Example 5 Synthesis of Compound 5

9,9-dimethylacridan (0.84 g, 4 mmol), 3-bromodibenzofuran (1.2 g, 5 mmol), tetrafluoroborate-tri-t-butylphosphine (70 mg, 0.24 mmol), sodium-t- Butoxide (0.46 g, 4.8 mmol) and tris (dibenzylideneacetone) dibaradium (0) (73 mg, 0.08 mmol) were placed in a three-necked flask, dehydrated toluene (40 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified using column chromatography (silica gel, chloroform: hexane = 4: 1) to obtain 1.1 g of Compound 5 as a white powder in a yield of 63%.
¹ HNMR (500 MHz, CDCl ₃ ): δ 8.12 (d, J = 8.0 Hz, 1H, g), 7.97 (dd, J = 1.0, 7.0 Hz, 1H, f), 7.56 (Dd, J = 0.5, 8.0 Hz, 1H, korh), 7.51 (ds, J = 1.5 Hz, 1H, l), 7.45 (dt, J = 1.5, 8.0 Hz) , 1H, iorj), 7.41 (dd, J = 2.0, 7.0 Hz, 2H, bore), 7.35 (dt, J = 1.0, 7.5 Hz, 1H, iorj), 7. 25 (dd, J = 2.0, 8.0 Hz, 2H, korh), 6.87 (m, 4H, c, d), 6.24 (dd, J = 2.0, 7.5 Hz, 2H, bore), 1.66 (s, 6H, a)
MS (ASAP) m / z 376.11 [MH ⁺ ]

Synthesis Example 6 Synthesis of Compound 6

9,9-dimethylacridan (2.1 g, 10 mmol), 4-bromodibenzofuran (2.2 g, 9 mmol), tetrafluoroboric acid-tri-t-butylphosphine (0.16 g, 0.54 mmol), sodium t-Butoxide (1.0 g, 11 mmol) and tris (dibenzylideneacetone) dibaradium (0) (0.17 g, 0.54 mmol) were placed in a three-necked flask, dehydrated toluene (90 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified using column chromatography (silica gel, dichloromethane: hexane = 1: 4) to obtain 2.6 g of a white powder compound 6 in a yield of 75%.
¹ HNMR (500 MHz, CDCl ₃ ): δ 8.15 (dd, J = 1.5, 8.0 Hz, 1H, h), 8.06 (dd, J = 0.5, 7.5 Hz, 1H, f) 7.60 (t, J = 8.0 Hz, 1H, g), 7.55 (dd, J = 2.5, 7.0 Hz, 2H, bore), 7.53 (dd, J = 1.5 , 8.0 Hz, 1H, iorl), 7.47 (m, 2H), 7.41 (m, 1H, jork), 6.98 (m, 4H, c, d), 6.32 (dd, J = 2.0, 7.5 Hz, 2H, bore), 1.83 (s, 6H, a)
MS (ASAP) m / z 376.10 [MH ⁺ ]

(Synthesis Example 7) Synthesis of Compound 7

9,9-dimethylacridan (1.5 g, 7 mmol), 2,8-dibromodibenzofuran (0.98 g, 3 mmol), tetrafluoroboric acid-tri-t-butylphosphine (70 mg, 0.24 mmol), sodium t-Butoxide (0.46 g, 4.8 mmol) and tris (dibenzylideneacetone) dibaladium (0) (73 mg, 0.08 mmol) were placed in a three-necked flask, dehydrated toluene (40 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified using column chromatography (silica gel, dichloromethane: hexane = 1: 4) to obtain Compound 7 as a white powder in a yield of 1.5 g and a yield of 86%.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 8.31 (ds, J = 2.0 Hz, 2H, h), 8.09 (d, J = 8.5 Hz, 2H, a), 7.56 (dd , J = 2.0, 8.5 Hz, 2H, b), 7.49 (dd, J = 1.5, 7.5 Hz, 4H, corf), 6.96 (dt, J = 1.5, 7) .5 Hz, 4H, dore), 6.90 (dt, J = 1.5, 7.5 Hz, 4H, dore), 6.21 (dd, J = 1.5, 8.0 Hz, 4H, corf), 1.64 (s, 12H, g)
MS (ASAP) m / z 583.54 [MH ⁺ ]

Synthesis Example 8 Synthesis of Compound 8

2-methoxy-4-bromophenylboronic acid (2.3 g, 10 mmol), 2-fluoro-4-bromoiodobenzene (15 g, 50 mmol), cesium carbonate (9.8 g, 30 mmol), tetrakis (triphenylphosphine) palladium (0) (0.23 g, 0.2 mmol) was placed in a three-necked flask, purged with argon and then degassed toluene (15 mL), ethanol (5 mL), water (5 mL) were added, and the mixture was stirred at 100 ° C. for 14 hours. . After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Water was added for liquid separation, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, the solvent was removed using an evaporator. The residue was purified by column chromatography (silica gel, chloroform: hexane = 1: 9) to obtain a light yellow oily intermediate 4 in a yield of 2.7 g and a yield of 74%.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 7.60 (dd, J = 2.0, 9.5 Hz, 1H, a), 7.47 (dd, J = 2.0, 8.5 Hz, 1H, b), 7.33 (ds, J = 1.5 Hz, 1H, e), 7.31 (t, J = 8.0 Hz, 1H, c), 7.24 (dd, J = 2.0, 8 .0Hz, 1H, f), 7.19 (d, J = 8.0 Hz, 1H, g), 3.78 (s, 3H, d)
MS (ASAP) m / z 359.94 [M ⁺ ]

Intermediate 4 (2.3 g, 6.3 mmol) and pyridine hydrochloride (12 g, 0.1 mol) were added to a three-necked flask, and the mixture was heated to 180 ° C. and stirred overnight while flowing nitrogen gas. After confirming that all the raw materials were consumed by TLC, the mixture was allowed to cool to about room temperature, 100 mL of water was added, and the mixture was stirred for 30 minutes while ice bathing. The product was then extracted with chloroform and the solution was dried over sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, chloroform was removed by an evaporator. The residue was purified using column chromatography (silica gel, chloroform: hexane = 4: 1) to obtain 2.04 g of a white powder intermediate 5 in 94% yield.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 10.25 (br, 1H, d), 7.59 (dd, J = 2.0, 10 Hz, 1H, a), 7.46 (dd, J = 2) 0.0, 8.5 Hz, 1 H, b), 7.33 (t, J = 8.0 Hz, 1 H, c), 7.13 (d, J = 8.0 Hz, 1 H, g), 7.10 ( ds, J = 2.0 Hz, 1H, e), 7.05 (dd, J = 1.5, 8.0 Hz, 1H, f)
MS (ASAP) m / z 345.90 [M ⁺ ]

Intermediate 5 (1.73 g, 5 mmol), potassium carbonate (1.11 g, 8 mmol) and 1-methyl-2-pyrrolidone (100 mL) were added to a three-necked flask, and after bubbling with nitrogen, the temperature was raised to 180 ° C. Stir for hours. After confirming that all the raw materials were consumed by TLC, the reaction solution was poured into 900 mL of water after being allowed to cool to about room temperature. The precipitate was collected by filtration under reduced pressure, washed with water and dried to obtain 1.56 g of a white powder intermediate 6 in a yield of 96%.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 8.15 (d, J = 8.5 Hz, 2H, c), 8.06 (ds, J = 1.5 Hz, 2H, a), 7.63 (dd , J = 2.0, 8.5 Hz, 2H, b); MS (ASAP) m / z 325.84 [M ⁺ ]

9,9-dimethylacridan (1.1 g, 5 mmol), intermediate 6 (0.65 g, 2 mmol), tetrafluoroboric acid-tri-t-butylphosphine (87 mg, 0.3 mmol), sodium-t-butoxide (0.58 g, 6 mmol) and tris (dibenzylideneacetone) dibaladium (0) (92 mg, 0.1 mmol) were placed in a three-necked flask, dehydrated toluene (40 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified using column chromatography (silica gel, chloroform) and washed with ethanol to obtain Compound 8 as a pale yellow powder in a yield of 0.63 g and a yield of 55%.
¹ HNMR (500 MHz, CDCl ₃ ): δ 8.27 (d, 2H, h), 7.64 (ds, J = 1.5 Hz, 2H, a), 7.49 (dd, J = 2.5, 8 0.0 Hz, 4H, b), 7.39 (dd, J = 1.5, 8.0 Hz, 2H, g), 699-6.94 (m, 8H, c, d), 6.33 ( dd, J = 2.0, 7.0 Hz, 4H, e), 1.74 (s, 12H, f)
MS (ASAP) m / z 583.39 [MH ⁺ ]

Synthesis Example 9 Synthesis of Compound 9

9,9-dimethylacridan (1.1 g, 5 mmol), 4,6-dibromodibenzofuran (0.65 g, 2 mmol), tetrafluoroborate-tri-t-butylphosphine (87 mg, 0.3 mmol), sodium t-Butoxide (0.58 g, 6 mmol) and tris (dibenzylideneacetone) dibaladium (0) (92 mg, 0.1 mmol) were placed in a three-necked flask, dehydrated toluene (40 mL) was added, and the mixture was stirred and refluxed overnight. After confirming that all the raw materials were consumed by TLC, the reaction was stopped and allowed to cool. Thereafter, the reaction solution was washed with water, and the organic layer was taken out and dried using sodium sulfate. After removing sodium sulfate by filtration under reduced pressure, toluene was removed using an evaporator. The residue was purified using column chromatography (silica gel, chloroform: hexane = 1: 3) to obtain white powder of Compound 9 in a yield of 1.0 g and a yield of 88%.
¹ HNMR (500 MHz, DMSO-d ₆ ): δ 8.47 (dd, 2H, h), 7.70 (t, J = 8.0 Hz, 2H, g), 7.57 (dd, J = 1.5) , 8.0 Hz, 2H, f), 7.33 (m, 4H, aord), 6.80 (m, 8H, b, c), 6.10 (m, 4H, aord), 1.42 (s , 12H, e)
MS (ASAP) m / z 583.26 [MH ⁺ ]

Example 1 Preparation and Evaluation of Solution Compound 1 and Compound 2 were dissolved in toluene to prepare 1.0 × 10 ⁻⁵ mol / L toluene solutions, respectively.
UV-visible absorption, fluorescence, and phosphorescence spectra of a toluene solution of Compound 1 were measured. The fluorescence maximum wavelength was 425 nm, and the phosphorescence maximum wavelength was 443 nm. S1, estimated from the emission end of the fluorescence and phosphorescence spectra 2.92 eV, T1 is 2.80 eV, the value of Delta] E _ST was 0.12 eV.
About each toluene solution of the compound 1 and the compound 2, the light emission quantum yield (PLQY) was measured about each when the bubbling of nitrogen gas was not performed and when it performed. In addition, the fluorescence intensity decay curve was measured to determine the lifetime τ _p of the immediate fluorescence component and the lifetime τ _d of the delayed fluorescence component. The measurement results are shown in Table 1. Since the emission quantum yield and the lifetime are improved by bubbling nitrogen gas, it was confirmed that the delayed component is delayed fluorescence via the T ₁ excited state.

For compounds 3-9 also to prepare a toluene solution of ^{1.0 × 10 -5 mol / L,} S1, T1, was determined ΔΔE _ST. In addition, the emission quantum yield (PLQY) was measured for each of the cases where nitrogen gas was not bubbled and when nitrogen gas was not bubbled. These results are summarized in Table 2. The PLQY with nitrogen gas bubbling improved the fluorescence lifetime in any solution by bubbling nitrogen gas.

(Example 2) Production and Evaluation of Thin Film A thin film made of only Compound 1 was formed on a Si substrate by a vacuum deposition method. Separately, compound 1 and dibenzothiophene-2,8-bis-diphenylphosphine oxide (PPT: HOMO energy level −6.6 eV, LUMO energy level −2.9 eV) on a Si substrate. By co-evaporation from different deposition sources, a co-evaporation film containing 5% by weight of Compound 1 was produced.
The thin film consisting only of Compound 1 was subjected to photoelectron yield spectroscopy measurement and UV-visible absorption spectrum measurement using AC-3 manufactured by Riken Keiki Co., Ltd. The HOMO energy level of Compound 1 estimated from the photoelectron yield spectroscopic measurement result and the absorption edge wavelength of the UV-visible absorption spectrum was −6.1 eV, and the LUMO energy level was −3.0 eV.
When the emission spectrum was measured for each of the thin film consisting only of Compound 1 and the co-deposited film, the same fluorescence spectrum was obtained for each film, and the maximum emission wavelength was 485 nm. The light emission quantum yield (PLQY) of the co-deposited film was measured and found to be 17% under the atmosphere and 21% under the argon stream. Further, FIG. 2 shows the results of measuring the emission intensity decay curves of the co-deposited films at respective temperatures of 6K, 50K, 100K, 150K, 200K, 250K, and 300K with a streak camera. At 4 μs, the emission intensity increased in the order of 250K, 300K, 200K, 150K, 100K, 50K, and 6K. Since the fluorescence delay component increases with the temperature rise, it was confirmed that Compound 1 is a thermally activated delayed fluorescence material. A streak camera (C4334 manufactured by Hamamatsu Photonics) and a nitrogen gas laser (337 nm) were used for the measurement.

The

compounds

3, 4, 8, and 9 were co-evaporated with the host materials shown in Table 3 to prepare a co-evaporated film having a concentration of 6% by weight. Table 3 shows the results of measuring the light emission quantum yield (PLQY) of each co-deposited film under the atmosphere and argon. In addition, FIG. 3 shows the results of measuring the emission intensity decay curves of the vapor deposition film of compound 9 at temperatures of 30K, 100K, 200K, and 300K with a streak camera. Since the fluorescence delay component increased with the temperature rise, it was confirmed that Compound 9 is a thermally activated delayed fluorescence material.

Example 3 Production and Evaluation of Organic Electroluminescence Element A glass substrate (manufactured by Atsugi Micro Co., Ltd.) on which an ITO transparent electrode was patterned with a film thickness of 100 nm was cut into a size of 25 nm in length and 25 nm in width and washed. The following layers were formed on this substrate at 3 to 7 × 10 ⁻⁴ Pa using a vacuum vapor deposition machine (manufactured by ALS Technology). First, α-NPD was formed on ITO to a thickness of 35 nm, and mCP was formed thereon to a thickness of 10 nm. Next, Compound 1 and PPT were co-evaporated from different vapor deposition sources to form a 20 nm thick layer as a light emitting layer. At this time, the concentration of Compound 1 was 5% by weight. Next, PPT is formed to a thickness of 40 nm, lithium fluoride (LiF) is further vacuum-deposited to 0.8 nm, and then aluminum (Al) is evaporated to a thickness of 80 nm to form a cathode. A luminescence element was obtained.
When the emission spectrum of the produced organic electroluminescence device was measured, it almost coincided with the emission spectrum of the co-deposited film of Example 2. Next, when the current density-voltage characteristic and the luminous flux-voltage characteristic of the produced organic electroluminescence element were measured, the driving voltage of 10 mA / cm ² was 12 V, and the luminous flux was 2.98 × 10 ⁻³ cd / cm ^2. Met. When the external quantum efficiency-current density characteristic was measured, the external quantum efficiency at 0.15 mA / cm ² was 2.2%. For measurement of these characteristics, an OLED integrating sphere (PMA-12 manufactured by Hamamatsu Photonics) and a luminance light distribution measuring device (A10119 manufactured by Hamamatsu Photonics) were used.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Cathode

Claims

A light emitting material comprising a compound that satisfies any of the following conditions (A) to (C).
(A) A compound having a structure in which two different acceptor groups are bonded to each other.
(B) A compound having a structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked.
(C) A compound having a structure in which two different donor groups are bonded to each other.
The luminescent material according to claim 1, which is a delayed fluorescent material.
From the difference Delta] E ST excited singlet energy level E S1 and the lowest excited triplet energy level E T1 is less than 0.4 eV, the light emitting material according to claim 1 or 2 of said compound.
The luminescent material according to any one of claims 1 to 3, wherein the compound satisfies the condition (A).
The luminescent material according to any one of claims 1 to 3, wherein the compound satisfies the condition (B).
The luminescent material according to any one of claims 1 to 3, wherein the compound is represented by the following general formula (1).

[In the general formula (1), R 1 to R 8 each independently represents a hydrogen atom or a substituent, and R 9 represents a substituent. R 1 and R 2 , R 2 and R 3 , R 3 and R 4 , R 5 and R 6 , R 6 and R 7 , R 7 and R 8 , R 4 and R 9 , R 5 and R 9 are respectively They may be bonded to each other to form a cyclic structure. Z represents an electron withdrawing group. However, the general formula (1) satisfies the above (A) or (B). ]
Z in the general formula (1) is> C = O,> C = C (CN) 2 ,> BR 10 ,> SO 2 ,> C (CF 3 ) 2 ,> P (═O) R 11 Or it is S, R < 10 > and R < 11 > represents a substituent each independently and satisfy | fills said (A) or (B), The luminescent material of Claim 6.
The luminescent material according to claim 6, wherein Z in the general formula (1) is> C = O. *
The luminescent material according to any one of claims 6 to 8, wherein R 9 in the general formula (1) is an acceptor group and satisfies the (A).
The light emitting material according to claim 9, wherein R 9 in the general formula (1) is a substituted or unsubstituted triazinyl group.
The luminescent material according to claim 10, wherein R 9 in the general formula (1) is a substituted or unsubstituted diaryltriazinyl group.
The luminescent material according to any one of claims 6 to 8, wherein R 1 in the general formula (1) is a donor group and satisfies the (B).
The luminescent material according to claim 12, wherein R 1 in the general formula (1) is a substituted or unsubstituted carbazolyl group.
The luminescent material according to claim 12 or 13, wherein R 9 in the general formula (1) is a substituted or unsubstituted aryl group.
The luminescent material according to any one of claims 1 to 3, wherein the compound satisfies the condition (C).
The light emitting material according to claim 15, wherein the compound includes a structure in which an optionally substituted acridan ring and an optionally substituted dibenzofuran ring are bonded.
The light-emitting material according to claim 15, wherein the compound includes a structure in which two optionally substituted acridan rings are bonded to an optionally substituted dibenzofuran ring.
The luminescent material according to claim 16 or 17, which is bonded to the dibenzofuran ring by a nitrogen atom constituting the acridan ring.
The luminescent material according to any one of claims 16 to 18, wherein the acridan ring is bonded to the 4-position of the dibenzofuran ring.
The luminescent material according to any one of claims 15 to 19, wherein the compound has a structure represented by the following general formula (2).

[In General Formula (2), D represents a dibenzofuran ring group which may be substituted or a dibenzothiophene ring group which may be substituted. R 11 to R 20 each independently represents a hydrogen atom or a substituent. R 11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 15 and R 16 , R 16 and R 17 , R 17 and R 18 , R 18 and R 19 , R 19 and R 20 , R 20 And R 11 may be bonded to each other to form a cyclic structure. n represents an integer of 1 to 4. However, the general formula (2) satisfies the above (C). ]
21. The luminescent material according to claim 20, wherein n is 2.
The luminescent material according to claim 21, wherein D represents an optionally substituted dibenzofuran-4,6-diyl group or an optionally substituted dibenzothiophene-4,6-diyl group.
21. The luminescent material according to claim 20, wherein n is 1.
An organic light emitting device comprising the light emitting material according to any one of claims 1 to 23.
The organic light-emitting device according to claim 24, which is an organic electroluminescence device.
Use of a compound satisfying any one of the following conditions (A) to (C) as a delayed fluorescent material.
(A) A compound having a structure in which two different acceptor groups are bonded to each other.
(B) A compound having a structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked.
(C) A compound having a structure in which two different donor groups are bonded to each other.
A compound represented by the following general formula (1).

[In the general formula (1), R 1 to R 8 each independently represents a hydrogen atom or a substituent, and R 9 represents a substituent. R 1 and R 2 , R 2 and R 3 , R 3 and R 4 , R 5 and R 6 , R 6 and R 7 , R 7 and R 8 , R 4 and R 9 , R 5 and R 9 are respectively They may be bonded to each other to form a cyclic structure. Z represents an electron withdrawing group. However, general formula (1) satisfies the following (a) or (b).
(A) It has a structure in which two different acceptor groups are bonded to each other.
(B) A structure in which a donor group having a Hammett σp value of −0.5 or more and less than 0 and an acceptor group having a Hammett σp value of more than 0 and 0.5 or less are linked. ]
A compound represented by the following general formula (2).

[In General Formula (2), D represents an optionally substituted dibenzofuran or an optionally substituted dibenzothiophene. R 11 to R 20 each independently represents a hydrogen atom or a substituent. R 11 and R 12 , R 12 and R 13 , R 13 and R 14 , R 15 and R 16 , R 16 and R 17 , R 17 and R 18 , R 18 and R 19 , R 19 and R 20 , R 20 And R 11 may be bonded to each other to form a cyclic structure. n represents an integer of 1 to 4. However, the general formula (2) has a structure in which two different donor groups are bonded to each other. When n in the general formula (2) is 2, R 11 to R 18 are hydrogen atoms, R 19 and R 20 are methyl groups, and D is an unsubstituted dibenzofuran-2,8-diyl group. There is no. ]