Intramolecular TTA upconversion material and organic light emitting device

Abstract

To provide a TTA upconversion material capable of achieving both a high emission quantum yield and a high TTA-UC efficiency, and an organic light emitting device that efficiently emits upconverted light by TTA.SOLUTION: A solid-state intramolecular TTA upconversion material includes two or more condensed polycyclic aromatic hydrocarbon structures, and is consists of a compound in which the distance between the benzene rings of two condensed polycyclic aromatic hydrocarbon structures is within the range of 4.5 to 5.0 Å.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to an energy-efficient intramolecular TTA upconversion material and an organic light-emitting device using the same. [Background technology]

[0002] TTA upconversion is a known mechanism for generating an excited singlet state from an excited triplet state and then producing light from the excited singlet state. Specifically, in TTA upconversion, triplet-triplet annihilation (TTA) occurs due to the interaction of two triplet excitons, generating a singlet exciton with higher energy than the triplet exciton. Light is then emitted as upconversion light through radiative deactivation from this singlet exciton. As a result, the energy of the excited triplet state, which is deactivated without radiation at room temperature, can be effectively utilized to generate high-energy light. Therefore, TTA upconversion is attracting attention as a light emission mechanism for organic light-emitting devices, and research and development of materials exhibiting TTA upconversion are actively underway. For example, 9,10-diphenylanthracene has been reported as a compound that exhibits TTA upconversion (Non-Patent Literature 1). In this study, it was confirmed that TTA is generated when compound molecules of 9,10-diphenylanthracene, which are in an excited triplet state in solution, collide with each other, and that upconversion light is emitted from the excited singlet state generated as a result. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Phys. Chem. Chem. Phys., 2012, 14, 4322-4332 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, TTA upconversion materials such as 9,10-diphenylanthracene are intermolecular TTA upconversion materials in which TTA occurs through the interaction of compound molecules in the excited triplet state. In order to increase the energy conversion efficiency from excited triplet energy to excited singlet energy (TTA-UC efficiency) in such intermolecular TTA upconversion materials, it is necessary to increase the compound concentration to a certain extent to bring the compound molecules closer together and increase the probability of TTA generation. However, if the compound concentration is increased, the emission quantum yield will decrease due to concentration quenching, leading to a decrease in the efficiency of the light-emitting device. Therefore, it has been difficult to achieve both high emission quantum yield and high TTA-UC efficiency in intermolecular TTA upconversion materials, and there has been a limit to improving the efficiency of light-emitting devices. Therefore, the inventors of this invention conducted research with the aim of providing a TTA upconversion material that exhibits high TTA-UC efficiency even at low concentrations, achieving both high luminescence quantum yield and high TTA-UC efficiency, and an organic light-emitting element that efficiently emits upconversion light by TTA. [Means for solving the problem]

[0005] As a result of diligent research to solve the above problems, the inventors have found that a solid compound having two or more condensed polycyclic aromatic hydrocarbon structures, where the distance between the benzene rings of two of these condensed polycyclic aromatic hydrocarbon structures is within a specific distance range, exhibits high TTA-UC efficiency even at low concentrations, and that it is possible to achieve both high emission quantum yield and high TTA-UC efficiency. The present invention is proposed based on these findings and has the following specific configuration.

[0006] [1] A solid-state intramolecular TTA upconversion material comprising a compound having two or more condensed polycyclic aromatic hydrocarbon structures, wherein the distance between the benzene rings of two of these condensed polycyclic aromatic hydrocarbon structures is within the range of 4.5 to 5.0 Å. [2] The intramolecular TTA upconversion material according to [1], wherein the distance between the benzene rings is in the range of 4.5 to 4.8 Å. [3] The intramolecular TTA upconversion material according to [1] or [2], wherein the condensed polycyclic aromatic hydrocarbon structure has a structure in which 2 to 4 benzene rings are condensed. [4] The intramolecular TTA upconversion material according to any one of [1] to [3], wherein the condensed polycyclic aromatic hydrocarbon structure comprises a condensed aromatic group composed of a condensed aromatic ring selected from the group consisting of a naphthalene ring, anthracene ring, phenalene ring, phenanthrene ring, pyrene ring, triphenylene ring, chrysene ring, and tetracene ring. [5] The intramolecular TTA upconversion material according to any one of [1] to [4], wherein the two condensed polycyclic aromatic hydrocarbon structures are identical in structure. [6] The intramolecular TTA upconversion material according to any one of [1] to [5], wherein the compound further has a multi-resonance condensed polycyclic structure. [7] The intramolecular TTA upconversion material according to any one of [1] to [6], wherein the compound has a structure in which the two condensed polycyclic aromatic hydrocarbon structures are bonded to a benzene ring. [8] The intramolecular TTA upconversion material according to [7], wherein the two condensed polycyclic aromatic hydrocarbon structures are bonded to the 1st and 2nd positions of the benzene ring, respectively. [9] The intramolecular TTA upconversion material according to [7] or [8], wherein the two condensed polycyclic aromatic hydrocarbon structures are bonded to the 1st and 2nd positions of the benzene ring, respectively, via 1,4-phenylene groups.

[10] The intramolecular TTA upconversion material according to any one of [7] to [9], wherein a multiple resonance condensed polycyclic structure is bonded to the benzene ring.

[11] The intramolecular TTA upconversion material according to [1], wherein the compound is a compound represented by the following general formula (2). [ka] [In general formula (2), Ar1 and Ar 2 each independently represents a polycondensed polycyclic aromatic hydrocarbon structure, and the distance between the benzene rings of the two polycondensed polycyclic aromatic hydrocarbon structures is 4.5 to 5.0 Å. L 1 and L 2 each independently represents a single bond, a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group, R 1 ~R 4 each independently represents a hydrogen atom or a substituent. R 1 and R 2 、R 2 and R 3 、R 3 and R 4 may be bonded to each other to form a benzene ring.]

[12] Any one of R 1 ~R 4 in the general formula (2) is a substituent having a multiple resonance type condensed polycyclic structure, the intramolecular TTA upconversion material according to

[11] .

[13] R 2 in the general formula (2) is a substituent having a multiple resonance type condensed polycyclic structure, the intramolecular TTA upconversion material according to

[11] or

[12] .

[14] The compound has a multiple resonance type condensed polycyclic structure represented by the following general formula (A) or (B), the intramolecular TTA upconversion material according to [1]. [Chemical formula] [In the general formula (A), X 1 represents a boron atom, C=O or C=S. R a ~R i each independently represents a hydrogen atom, a deuterium atom or a substituent. However, at least one of R a ~R i is an aryl group in which a polycondensed polycyclic aromatic hydrocarbon structure is bonded by a single bond or a linking group. R a and R b 、R b and R c 、R c and R d 、R d ​e , R f and R g , R g and R h , R h and R i , R i and R a These may be joined together to form a ring structure. 1 When is a boron atom, R e and X 1 , X 1 and R f These atoms bond to each other, forming the ring skeleton as X 1 It may also form a cyclic structure that does not contain heteroatoms. In general formula (B), X represents a boron atom, a nitrogen atom, Si-R, P=O, or P=S. 1 and Y 2 Each of these independently represents a boron atom, nitrogen atom, oxygen atom, sulfur atom, C=O, C=S, and SO2. However, X is Y. 1 and Y 2 This is different from X. R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkyl group. j ~R t Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. However, R j ~R t At least one of them is an aryl group in which a condensed polycyclic aromatic hydrocarbon structure is linked by a single bond or a linking group. j and R k , R k and R l , R l and R m , R m and R n , R n and R o , R o and R p , R p and R q , R r and R s , R s and R t These may be joined together to form a ring structure. 1 When R is a nitrogen atom or a boron atom, t and Y1 , Y 1 and R j These may be joined together to form a ring structure. 2 When R is a nitrogen atom or a boron atom, q and Y 2 , Y 2 and R r These elements may be bonded to each other to form a ring structure.

[15] Organic light-emitting element comprising an intramolecular TTA upconversion material described in any one of the items [1] to

[14] .

[16] Organic light-emitting element having a light-emitting layer comprising an intramolecular TTA upconversion material and a host material as described in any one of [1] to

[14] .

[17] Organic light-emitting element having a light-emitting layer comprising an intramolecular TTA upconversion material, a delayed fluorescence material, and a host material, as described in any one of items [1] to

[14] . [Effects of the Invention]

[0007] The intramolecular TTA upconversion material of the present invention exhibits high luminescence quantum yield and high TTA-UC efficiency. By using this intramolecular TTA upconversion material as the material for the light-emitting layer, it is possible to realize an organic light-emitting device that efficiently emits upconversion light by TTA. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing the shortest distance and centroidal distance between two anthracene structures of compound 1 and comparative compounds 1-4. [Figure 2] This graph shows the transient EL curves of EL elements 1a and 1b fabricated in Example 1, as well as the fitting curves using the TTA model and the Trap RC model. [Figure 3] This is the emission spectrum of EL element 2 fabricated in Example 2. [Figure 4] This graph shows the transient EL curve of EL element 2 fabricated in Example 2, and the fitting curves using the TTA model and the Trap RC model. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below. The following descriptions of constituent elements may be based on representative embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits. Furthermore, the isotopes of hydrogen atoms present in the molecule of the compound used in the present invention are not particularly limited; for example, all hydrogen atoms in the molecule 1 H is fine, or part or all of it 2 It may also be H (deuterium D). In a preferred embodiment of the present invention, all hydrogen atoms in the molecule 1 It is H. In one aspect of the present invention, all hydrogen atoms in the molecule 2 It is H (deuterium D). In one aspect of the present invention, some of the hydrogen atoms in the molecule are 1 H, and the rest is 2 It is H (deuterium D). Note that in the description of this invention, the terms "substitution" or "substituent" are used in the following context: 2 H (Deuterium D), etc. 1 It does not contain hydrogen isotopes other than H.

[0010] <Intramolecular TTA Upconversion Material> The intramolecular TTA upconversion material of the present invention is a solid-state intramolecular TTA upconversion material comprising a compound having two or more condensed polycyclic aromatic hydrocarbon structures, wherein the distance between the benzene rings of two of these condensed polycyclic aromatic hydrocarbon structures is within the range of 4.5 to 5.0 Å. In the following description, the compounds constituting the intramolecular TTA upconversion material are referred to as "TTA-UC compounds," and among the two or more condensed polycyclic aromatic hydrocarbon structures possessed by the TTA-UC compound, two condensed polycyclic aromatic hydrocarbon structures in which the distance between benzene rings is within the range of 4.5 to 5.0 Å are sometimes referred to as the "first condensed polycyclic aromatic hydrocarbon structure" and the "second condensed polycyclic aromatic hydrocarbon structure," respectively. The two or more condensed polycyclic aromatic hydrocarbon structures may be identical or different. The first and second condensed polycyclic aromatic hydrocarbon structures may also be identical or different, but it is preferable that they be identical. In the "intramolecular TTA upconversion material" of the present invention, "intramolecular TTA upconversion" means that excited triplet states are generated in at least two parts of the molecule, and triplet-triplet annihilation (TTA) occurs due to the interaction between the excited triplet states of these two parts, generating an excited singlet state with higher energy than the excited triplet state. In the "intramolecular TTA upconversion material" of the present invention, excited triplet states are generated in at least two condensed polycyclic aromatic hydrocarbon structures of the TTA-UC compound, and an excited singlet state is generated due to the interaction between the excited triplet states generated in these two condensed polycyclic aromatic hydrocarbon structures. The intramolecular TTA upconversion material in which the excited singlet state is generated emits light due to the radiative deactivation of the excited singlet state. In the following description, the light generated by intramolecular TTA upconversion is referred to as "UC light," and the generation of UC light is referred to as "UC emission." The fact that a material exhibits intramolecular TTA upconversion can be confirmed by its transient electroluminescence characteristics or the efficiency of its electroluminescence characteristics.

[0011] In this invention, "solid state" means being in a solid state at 20°C and 1 atmosphere. The presence of a solid state can be confirmed by the transient electroluminescence characteristics or the efficiency of the electroluminescence characteristics. The "solid-state intramolecular TTA upconversion material" is preferably entirely in a solid state, but may contain less than 20% of a non-volatile liquid state.

[0012] In the present invention, the "condensed polycyclic aromatic hydrocarbon structure" refers to a structure having a condensed ring in which two or more monorings of hydrocarbons are condensed together sharing one side, having a planar cyclic polyene structure, and having an aromatic condensed ring as its ring skeleton, wherein the number of π electrons in the ring is 4n+2 (where n is an integer). Preferably, the condensed polycyclic aromatic hydrocarbon structure is a monovalent group (a monovalent group obtained by removing one hydrogen atom from the aromatic condensed ring) composed of this aromatic condensed ring. In the following description, the aromatic condensed ring constituting the ring skeleton of the condensed polycyclic aromatic hydrocarbon structure may be referred to as the "condensed aromatic ring," the monovalent group composed of the condensed aromatic ring may be referred to as the "condensed aromatic group," and the monorings of each hydrocarbon constituting the condensed aromatic ring may be referred to as the "constituent ring." The number of constituent rings in the condensed aromatic hydrocarbon structure is preferably 2 to 6, and more preferably 2 to 4. Furthermore, the condensed polycyclic aromatic hydrocarbon structure includes one or more benzene rings as constituent rings of the condensed aromatic ring. The condensed aromatic ring preferably contains two or more benzene rings, and more preferably has a structure in which two or more benzene rings are fused. Here, a preferred structure is one in which 2 to 6 benzene rings are fused, and a more preferred structure is one in which 2 to 4 benzene rings are fused. TTA-UC compounds having a condensed polycyclic aromatic hydrocarbon structure in which 2 to 4 benzene rings are fused tend to exhibit blue UC emission and are useful as blue light-emitting materials. Examples of condensed aromatic rings constituting a condensed polycyclic aromatic hydrocarbon structure include naphthalene rings, anthracene rings, phenalene rings, phenanthrene rings, pyrene rings, triphenylene rings, chrysene rings, tetracene rings, perylene rings, picene rings, pentaphene rings, pentacene rings, hexaphene rings, and benz(a)anthracene rings. The condensed polycyclic aromatic hydrocarbon structure is preferably composed of anthracenyl group, phenanthrenyl group, pyrenyl group, and perilenyl group, and more preferably 2-anthracenyl group, 9-anthracenyl group, 1-pyrenyl group, and 3-perilenyl group.

[0013] One or more hydrogen atoms of the condensed aromatic ring and condensed aromatic group constituting the condensed polycyclic aromatic hydrocarbon structure may be substituted with substituents. The substituents may be selected from, for example, substituent group A described below, or substituent group B described below. In particular, the substituents of the condensed aromatic ring and condensed aromatic group are preferably substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, or substituted or unsubstituted alkyl groups. The aryl group in "substituted or unsubstituted aryl group" may consist of a monocyclic aromatic ring, a fused ring formed by the fusion of two or more aromatic rings, or a linked ring formed by the linkage of two or more aromatic rings. When two or more aromatic rings are linked, they may be linked in a linear chain or in a branched chain. The number of carbon atoms in the aromatic ring constituting the aryl group is preferably 6 to 22, more preferably 6 to 18, even more preferably 6 to 14, and even more preferably 6 to 10. Specific examples of aryl groups include the phenyl group, naphthalenyl group, and biphenyl group. The heterocyclic ring constituting the heteroaryl group of the "substituted or unsubstituted heteroaryl group" may be a monocyclic ring, a fused ring formed by the fusion of one or more heterocyclic rings with an aromatic ring or a heterocyclic ring, or a linked ring formed by the linkage of one or more heterocyclic rings with an aromatic ring or a heterocyclic ring. The number of carbon atoms in the heterocyclic ring constituting the heteroaryl group is preferably 3 to 40, more preferably 5 to 22, even more preferably 5 to 18, even more preferably 5 to 14, and particularly preferably 5 to 10. Examples of heteroatoms constituting the heterocyclic ring include nitrogen atoms, oxygen atoms, and sulfur atoms. Specific examples of heterocyclic rings include pyridine rings, pyridazine rings, pyrimidine rings, triazole rings, and benzotriazole rings. The alkyl group in "substituted or unsubstituted alkyl group" may be linear, branched, or cyclic. The preferred number of carbon atoms is 1 to 20, more preferably 1 to 10, and even more preferably 1 to 6. Specific examples of alkyl groups include methyl, ethyl, n-propyl, and isopropyl groups. The aryl group, heteroaryl group, and alkyl group may be further substituted with substituents selected from substituent group A or substituent group B. The number of substituents on the condensed aromatic group may be, for example, 0 to 6, 0 to 4, 0 to 2, 1 to 6, or 2 to 6. Furthermore, the condensed aromatic group may be unsubstituted (no substituents).

[0014] The TTA-UC compound used in the present invention has two or more condensed polycyclic aromatic hydrocarbon structures in its molecule. In one aspect of the present invention, the TTA-UC compound has a structure in which two or more condensed polycyclic aromatic hydrocarbon structures are bonded to one atomic group (core skeleton) via a single bond or a linking group. The number of condensed polycyclic aromatic hydrocarbon structures possessed by the TTA-UC compound is preferably 2 or more, more preferably 2 to 4, and even more preferably 2 or 3. And particularly, in the intramolecular TTA upconversion material of the present invention, among the two or more condensed polycyclic aromatic hydrocarbon structures possessed by the TTA-UC compound, the distance between the benzene rings of two condensed polycyclic aromatic hydrocarbon structures (the first condensed polycyclic aromatic hydrocarbon structure and the second condensed polycyclic aromatic hydrocarbon structure) is within the range of 4.5 to 5.0 Å. Thereby, even when the concentration of the TTA-UC compound is low, triplet excited state interaction and Dexter energy transfer easily occur between the two condensed polycyclic aromatic hydrocarbon structures present in the molecule, and TTA upconversion can occur efficiently. Further, the intramolecular TTA upconversion material of the present invention has the lowest excited triplet energy level E of the condensed polycyclic aromatic hydrocarbon structure. T1 Compared to S1 , the lowest excited singlet energy level E of the excited singlet state generated by TTA upconversion is higher, and therefore E T1 and E S1Because the energies are relatively far apart, it has the advantage of high energy conversion efficiency from excited triplet energy to excited singlet energy (TTA-UC efficiency). Therefore, the intramolecular TTA upconversion material of the present invention can achieve high TTA-UC efficiency while suppressing concentration quenching at low concentrations, and can achieve both high emission quantum yield and high TTA-UC efficiency. Here, from the viewpoint of further increasing TTA-UC efficiency, the distance between the benzene rings of the two condensed polycyclic aromatic hydrocarbon structures is preferably in the range of 4.5 to 4.8 Å. In the case of three or more condensed polycyclic aromatic hydrocarbon structures, the distance between the benzene rings of one condensed polycyclic aromatic hydrocarbon structure other than the two condensed polycyclic aromatic hydrocarbon structures and the other condensed polycyclic aromatic hydrocarbon structures may be in the range of 4.5 to 5.0 Å or outside this range.

[0015] In this invention, the "distance between benzene rings of two condensed polycyclic aromatic hydrocarbon structures" specifically refers to the distance (shortest distance) between the centers of the closest combination of benzene rings among the combinations of benzene rings constituting the condensed aromatic ring of one of the two condensed polycyclic aromatic hydrocarbon structures (the first condensed polycyclic aromatic hydrocarbon structure) and the condensed aromatic ring constituting the condensed aromatic ring of the other (the second condensed polycyclic aromatic hydrocarbon structure). The distance between benzene rings can be determined, for example, in the case of a TTA-UC compound in which the first condensed polycyclic aromatic hydrocarbon structure and the second condensed polycyclic aromatic hydrocarbon structure are bonded to the core skeleton by single bonds or linking groups (e.g., phenylene groups), by setting the planar structure as follows. In other words, in a configuration where the benzene rings constituting the condensed aromatic ring of the first condensed polycyclic aromatic hydrocarbon structure and the benzene rings constituting the condensed aromatic ring of the second condensed polycyclic aromatic hydrocarbon structure lie in the same plane and the two condensed aromatic rings do not overlap, the planar structure is set by rotating the single bonds so that the closest combination of benzene rings between any of the benzene rings constituting one condensed aromatic ring and any of the benzene rings constituting the other condensed aromatic rings takes on a certain configuration (neighboring arrangement), and the distance between the centers of the closest combination of benzene rings is determined by X-ray single-crystal structure analysis. If X-ray structure analysis is not performed, it may be determined by quantum chemical calculation (B3LYP / 6-31G(d)). Here, if the first and second condensed polycyclic aromatic hydrocarbon structures are structures in which the single bonds are bonded to the core skeleton via linking groups, then the "structure in which single bonds are rotated to assume nearest neighbor configuration" described above refers to a structure in which the single bonds between the condensed aromatic ring and the linking group, and the single bonds between the linking group and the core skeleton, are rotated to assume nearest neighbor configuration. For example, in compounds where 3-perilenyl groups (condensed aromatic groups constituting the first and second condensed polycyclic aromatic hydrocarbon structures) are bonded to the 1st and 2nd positions of a benzene ring (core skeleton), if the condensed aromatic rings collide with each other depending on their orientation, then the following planar structure is set up so that the two condensed aromatic rings do not overlap, and the benzene ring b that is closest to the other condensed aromatic ring is selected from the combinations of benzene rings constituting one condensed aromatic ring and the benzene rings constituting the other condensed aromatic ring. 1 and benzene ring b 2 Measure the distance between the centers.

[0016] [ka]

[0017] Furthermore, in cases where the single bonds between the condensed aromatic group (3-perylenel group) and the linking group (1,4-phenylene group), and the single bonds between the linking group and the core skeleton (benzene ring), do not collide with each other even when rotated, as in the compounds shown below, the planar structure is set to the nearest-neighbor configuration shown below, where the benzene rings constituting each condensed aromatic ring are closest to each other. Among the combinations of benzene rings constituting one condensed aromatic ring and benzene rings constituting the other condensed aromatic ring, the benzene ring b that is closest in position is selected. 3 and benzene ring b 4 Measure the distance between the centers.

[0018] [ka]

[0019] In the planar structure set up as described above, it is preferable that the distance between the centroids of the first and second condensed polycyclic aromatic hydrocarbon structures is less than 8 Å, and more preferably less than 7.3 Å. This makes it easier for excited triplet states to interact with each other between the two condensed polycyclic aromatic hydrocarbon structures, thereby improving the TTA-UC efficiency. Here, the distance between centroids refers to the distance between the centroid of the condensed aromatic ring constituting the first condensed polycyclic aromatic hydrocarbon structure and the centroid of the condensed aromatic ring constituting the second condensed polycyclic aromatic hydrocarbon structure. For example, in a perylene ring, the center of the central benzene ring that shares four sides with other benzene rings corresponds to the "centroid," and in an anthracene ring, the center of the central benzene ring that shares two sides with other benzene rings corresponds to the "centroid."

[0020] The distance between the benzene rings in the first and second condensed polycyclic aromatic hydrocarbon structures can be adjusted by controlling the structure of the core skeleton and the bond positions in the core skeleton of each condensed polycyclic aromatic hydrocarbon structure. Furthermore, it can also be adjusted by introducing linking groups between each condensed polycyclic aromatic hydrocarbon structure and the atomic group, and controlling the type of linking group and the number of constituent atoms. Here, the core skeleton to which two or more condensed polycyclic aromatic hydrocarbon structures are bonded is preferably an aromatic ring, and more preferably a monocyclic aromatic ring. The aromatic ring may be an aromatic ring of hydrocarbons or an aromatic heterocyclic ring containing heteroatoms, but it is preferably an aromatic ring of hydrocarbons, and particularly preferably a benzene ring. When the core skeleton is a benzene ring, the bonding positions of the first condensed polycyclic aromatic hydrocarbon structure and the second condensed polycyclic aromatic hydrocarbon structure on the benzene ring are preferably at positions 1 and 2 or 1 and 3, and more preferably at positions 1 and 2. Examples of aromatic heterocyclic rings that can be used for the core skeleton include thiophene rings, furan rings, pyrrole rings, and pyridine rings. Hydrogen atoms other than those at the bonded positions of the condensed polycyclic aromatic hydrocarbon structure of the core skeleton may be substituted with substituents. For a description of substituents, preferred ranges, and specific examples, refer to the description of substituents that may be substituted on the condensed aromatic ring, preferred ranges, and specific examples above. However, here, aryl groups composed of condensed rings will be classified as "condensed polycyclic aromatic hydrocarbon structures." Furthermore, hydrogen atoms of the core skeleton may be substituted with substituents having a multi-resonance condensed polycyclic structure as described later. The substituents having a multi-resonance condensed polycyclic structure introduced into the core skeleton may be one or two or more. When introducing two or more substituents having a multi-resonance condensed polycyclic structure into the core skeleton, these multi-resonance condensed polycyclic structures may be identical or different. Substituents having a multi-resonance condensed polycyclic structure can be selected from Groups 1 to 10 below.

[0021] Furthermore, as described above, a linking group may be introduced between each condensed polycyclic aromatic hydrocarbon structure and the core skeleton in the TTA-UC compound. Examples of linking groups include substituted or unsubstituted arylene groups and substituted or unsubstituted heteroarylene groups, with substituted or unsubstituted arylene groups being preferred and substituted or unsubstituted phenylene groups being more preferred. The phenylene group may be any of 1,2-phenylene, 1,3-phenylene, or 1,4-phenylene groups, but 1,4-phenylene groups are preferred. Examples of heteroarylene groups that can be used as linking groups include divalent groups (divalent groups obtained by removing two hydrogen atoms from an aromatic heterocycle) composed of aromatic heterocycles selected from the group consisting of thiophene rings, furan rings, pyrrole rings, and pyridine rings. One or more hydrogen atoms of the arylene group and heteroarylene group constituting the linking group may be substituted with substituents. For descriptions of substituents, preferred ranges, and specific examples, please refer to the descriptions of substituents that may be substituted on the condensed aromatic ring, preferred ranges, and specific examples above. However, here, aryl groups composed of condensed rings will be classified as "condensed polycyclic aromatic hydrocarbon structures."

[0022] In a preferred embodiment of the present invention, the TTA-UC compound is a compound having a structure in which a first condensed polycyclic aromatic hydrocarbon structure and a second condensed polycyclic aromatic hydrocarbon structure are bonded to the 1st and 2nd positions of a benzene ring by single bonds, respectively. In another preferred embodiment of the present invention, the TTA-UC compound is a compound having a structure in which a first condensed polycyclic aromatic hydrocarbon structure and a second condensed polycyclic aromatic hydrocarbon structure are bonded to the 1st and 2nd positions of a benzene ring via 1,4-phenylene groups, respectively.

[0023] The TTA-UC compound used in the present invention is preferably a compound represented by the following general formula (1).

[0024] [ka]

[0025] In general formula (1), Ar1 and Ar 2 each represents a condensed polycyclic aromatic hydrocarbon structure, and the distance between the benzene rings of the two condensed polycyclic aromatic hydrocarbon structures is 4.5 to 5.0 Å. L 1 and L 2 each independently represents a single bond, a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group. Two hydrogen atoms of the benzene ring are -L 1 -Ar 1 and L 2 -Ar 1 substituted, and one or more of the remaining hydrogen atoms may be substituted with substituents, or the substituents may be bonded to each other to form a benzene ring. In general formula (1), for the description, preferred range and specific examples of the condensed polycyclic aromatic hydrocarbon structure and the distance between the benzene rings, reference can be made to the corresponding descriptions for the above TTA-UC compounds. For the description, preferred range and specific examples of the substituted or unsubstituted arylene group and the substituted or unsubstituted heteroarylene group, reference can be made to the descriptions for the substituted or unsubstituted arylene group and the substituted or unsubstituted heteroarylene group as the above linking group. For the description, preferred range and specific examples of the substituents that may substitute the benzene ring, reference can be made to the descriptions for the substituents in the above core skeleton. Ar 1 and Ar 2 may be of the same structure or different structures from each other, but preferably they are of the same structure. L 1 and L 2 may be of the same structure or different structures from each other, but preferably they are of the same structure.

[0026] The compound represented by general formula (1) is preferably a compound represented by the following general formula (2).

[0027]

Chemical formula

[0028] In general formula (2), Ar 1 and Ar 2 Each of these independently represents a condensed polycyclic aromatic hydrocarbon structure, and the distance between the benzene rings of the two condensed polycyclic aromatic hydrocarbon structures is 4.5 to 5.0 Å. 1 and L 2 Each of these independently represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, R 1 ~R 4 Each of these independently represents a hydrogen atom or a substituent. 1 and R 2 , R 2 and R 3 , R 3 and R 4 These elements may be bonded to each other to form a benzene ring. Ar 1 Ar 2 , L 1 and L 2 For an explanation of the general formula (1), see Ar 1 Ar 2 , L 1 and L 2 You can refer to the explanation about R. 1 ~R 4 They may be the same or different from each other. 1 ~R 4 For a description of the substituents, preferred ranges, and specific examples, please refer to the description of substituents in the core skeleton above.

[0029] The TTA-UC compound used in this invention may have a multiple resonance fused polycyclic structure within the molecule, in addition to the two or more fused polycyclic aromatic hydrocarbon structures described above. Here, "multiple resonance fused polycyclic structure" refers to a heterocyclic fused polycyclic aromatic structure having a conjugated π-electron system and two or more heteroatoms with a different number of valence electrons than carbon atoms, where each of these heteroatoms resonates, and the entire structure resonates in multiple ways. By introducing a multiple resonance fused polycyclic structure into the TTA-UC compound, the luminescence efficiency and color purity can be improved. Here, conventional multiple resonance luminescent materials that do not have the first and second fused polycyclic aromatic hydrocarbon structures have the characteristics of high luminescence efficiency and a narrow emission bandwidth (high color purity), but on the other hand, they have a long triplet lifetime, which has been a cause of device degradation. In contrast, in TTA-UC compounds having two condensed polycyclic aromatic hydrocarbon structures (first and second condensed polycyclic aromatic hydrocarbon structures) within a predetermined distance range and a multi-resonance condensed polycyclic structure, the excited triplet energy level of the condensed polycyclic aromatic hydrocarbon structure is low. As a result, the excited triplet energy generated in the multi-resonance condensed polycyclic structure is easily transferred to the condensed polycyclic aromatic hydrocarbon structure, and after triplet-triplet annihilation and upconversion to an excited singlet state in the two condensed polycyclic aromatic hydrocarbon structures, and the transfer of that excited singlet energy to the multi-resonance condensed polycyclic structure, it is emitted as UC light. Therefore, device degradation caused by long-lived triplet states, which was a problem in conventional multi-resonance luminescent materials, is suppressed, and higher luminescence efficiency can be obtained.

[0030] The two or more complex atoms included in the multiple resonance condensed polycyclic structure may be of the same type or different types. Examples of complex atoms include boron, nitrogen, oxygen, sulfur, silicon, and phosphorus. The multiple resonance condensed polycyclic structure preferably includes two or more complex atoms selected from the group consisting of boron, nitrogen, oxygen, and sulfur atoms, and more preferably includes two or more complex atoms selected from the group consisting of boron, nitrogen, and oxygen atoms. In a preferred embodiment of the present invention, the TTA-UC compound has a multiple resonance condensed polycyclic structure in its molecule that includes only boron and nitrogen atoms as complex atoms, and in another preferred embodiment of the present invention, the TTA-UC compound has a multiple resonance condensed polycyclic structure in its molecule that includes only boron, nitrogen, and oxygen atoms as complex atoms. In yet another preferred embodiment of the present invention, the TTA-UC compound has a multiple resonance condensed polycyclic structure in the molecule that contains only boron and oxygen atoms as complex atoms, and in yet another preferred embodiment of the present invention, the TTA-UC compound has a multiple resonance condensed polycyclic structure in the molecule that contains only nitrogen and oxygen atoms as complex atoms.

[0031] A preferred example of a multiple resonance fused polycyclic structure is a multiple resonance fused polycyclic structure having a structure in which a ring containing a complex atom as a constituent atom of the ring skeleton is fused with a benzene ring. A more preferred example is a multiple resonance fused polycyclic structure having a structure in which multiple benzene rings are fused via a ring containing a complex atom (a structure in which multiple benzene rings are fused to one complex ring). It is also preferable for a multiple resonance fused polycyclic structure to include a structure in which two or more nitrogen-containing aromatic rings are fused.

[0032] Specific examples of multiple resonance condensed polycyclic structures include structures represented by the following general formula (A) or general formula (B). [ka]

[0033] In general formula (A), X 1R represents a boron atom (B), C=O or C=S. a ~R i Each of these independently represents a hydrogen atom (H), a deuterium atom (D), or a substituent. However, R a ~R i At least one of them is an aryl group in which a condensed polycyclic aromatic hydrocarbon structure is linked by a single bond or a linking group. a and R b , R b and R c , R c and R d , R d and R e , R f and R g , R g and R h , R h and R i , R i and R a These may be joined together to form a ring structure. 1 When is a boron atom, R e and X 1 , X 1 and R f These atoms bond to each other, forming the ring skeleton as X 1 It may also form a cyclic structure that does not contain heteroatoms. Note that when a cyclic structure containing heteroatoms is formed, it is included in the following general formula (B). In one aspect of the present invention, X 1 X is a boron atom. In one aspect of the present invention, X 1 is C=O or C=S. In one aspect of the present invention, R a ~R i and X 1 Two of them are not bonded to each other to form a ring structure. In one aspect of the present invention, R a ~R i and X 1 Two of them are joined together to form a ring structure, X 1 It does not form a cyclic structure that includes heteroatoms other than those mentioned above as ring skeleton constituent atoms. In one aspect of the present invention, R a ~R iTwo of these are bonded together to form a cyclic structure containing heteroatoms as ring skeleton constituent atoms. In one aspect of the present invention, X 1 is a boron atom, and R a ~R i It does not contain heteroatoms. In one aspect of the present invention, R a ~R i The two are bonded to each other to form a cyclic structure containing heteroatoms as ring skeleton constituent atoms. In one aspect of the present invention, X 1 is a boron atom, and R a ~R i These two are bonded together to form a cyclic structure containing a boron atom and a nitrogen atom as ring skeleton constituent atoms. In one aspect of the present invention, X 1 C=O, and R a ~R i These two are bonded together to form a cyclic structure that includes the carbon and nitrogen atoms of the carbonyl group as constituent atoms of the ring skeleton. [ka]

[0034] In general formula (B), X represents a boron atom (B), a nitrogen atom (N), Si-R, P=O, or P=S. 1 and Y 2 Each of these independently represents a boron atom (B), a nitrogen atom (N), an oxygen atom (O), a sulfur atom (S), C=O, C=S, and SO2. However, X is Y. 1 and Y 2 This is different from X. R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkyl group. j ~R t Each of these independently represents a hydrogen atom, a deuterium atom, or a substituent. However, R j ~R t At least one of them is an aryl group in which a condensed polycyclic aromatic hydrocarbon structure is linked by a single bond or a linking group. j and R k , R k and R l , R l and R m , R m and R n, R n and R o , R o and R p , R p and R q , R r and R s , R s and R t These may be joined together to form a ring structure. 1 When R is a nitrogen atom or a boron atom, t and Y 1 , Y 1 and R j These may be joined together to form a ring structure. 2 When R is a nitrogen atom or a boron atom, q and Y 2 , Y 2 and R r These elements may be bonded to each other to form a ring structure. In one aspect of the present invention, X is a boron atom. In one aspect of the present invention, X is a nitrogen atom. In one aspect of the present invention, X is Si-R. In one aspect of the present invention, X is P=O or P=S. In one aspect of the present invention, Y 1 and Y 2 is a boron atom. In one aspect of the present invention, Y 1 and Y 2 is a nitrogen atom. In one aspect of the present invention, Y 1 and Y 2 is an oxygen atom. In one aspect of the present invention, Y 1 and Y 2 is a sulfur atom. In one aspect of the present invention, Y 1 and Y 2 is C=O, C=S, or SO2. In one aspect of the present invention, X is a nitrogen atom, and Y 1 and Y 2 X is a boron atom. In one aspect of the present invention, X is a nitrogen atom, and Y 1 and Y 2 C=O. In one aspect of the present invention, X is a boron atom, and Y 1 and Y 2 Each of these is independently a nitrogen atom, an oxygen atom, or a sulfur atom. In one aspect of the present invention, Y 1and Y 2 They are identical. In one aspect of the present invention, Y 1 and Y 2 The differences are. In one aspect of the present invention, X is a boron atom, and Y 1 and Y 2 X is a nitrogen atom. In one aspect of the present invention, X is a boron atom, and Y 1 and Y 2 X is an oxygen atom. In one aspect of the present invention, X is a boron atom, and Y 1 and Y 2 X is a sulfur atom. In one aspect of the present invention, X is a boron atom, and Y 1 is a nitrogen atom, Y 2 X is an oxygen atom. In one aspect of the present invention, X is a boron atom, and Y 1 is a nitrogen atom, Y 2 X is a sulfur atom. In one aspect of the present invention, X is a boron atom, and Y 1 is an oxygen atom, Y 2 That is a sulfur atom. In one aspect of the present invention, X is Si-R, and Y 1 and Y 2 is a nitrogen atom. In one aspect of the present invention, X is Si-R and Y 1 and Y 2 P=O or P=S. In one aspect of the present invention, X is P=O or P=S, and Y 1 and Y 2 is an oxygen atom. In one aspect of the present invention, X is P=O or P=S, and Y 1 and Y 2 is a sulfur atom. In one aspect of the present invention, X is P=O or P=S, and Y 1 and Y 2 That is SO2. In one aspect of the present invention, R j ~R t , Y 1 , Y 2 Two of them are not bonded to each other to form a ring structure. In one aspect of the present invention, R j ~R t , Y 1 , Y 2Two of them are joined together to form a ring structure, Y 1 , Y 2 It does not form a cyclic structure that includes heteroatoms other than those mentioned above as ring skeleton constituent atoms. In one aspect of the present invention, R j ~R t Two of these atoms are bonded together to form a cyclic structure containing heteroatoms as constituent atoms of the ring skeleton.

[0035] In general formulas (A) and (B), R a ~R i , X 1 , R j ~R t , Y 1 , Y 2 The cyclic structure formed by the bonding of two of these elements may be an aromatic ring or an antilipid ring, and may also contain a heteroatom. Furthermore, the cyclic structure may be a fused ring of two or more rings. Examples of heteroatoms here include boron, nitrogen, oxygen, sulfur, silicon, and phosphorus atoms, and it is preferable that they be selected from the group consisting of boron, nitrogen, oxygen, and sulfur atoms.

[0036] Examples of multiple resonance fused polycyclic structures include the following structures. A TTA-UC compound may contain only one multiple resonance fused polycyclic structure selected from the group consisting of the following structures, or it may contain two or more. When a TTA-UC compound contains two or more multiple resonance fused polycyclic structures, these multiple resonance fused polycyclic structures may be identical or different.

[0037] [ka] JPEG2023074478000010.jpg190163JPEG2023074478000011.jpg213170JPEG20230744780 00012.jpg199170JPEG2023074478000013.jpg168163JPEG2023074478000014.jpg218170

[0038] The above structures are divided into 10 groups, Groups 1 to 10, but a structure may be selected from any group. In one aspect of the present invention, the structure is selected from Group 1. In one aspect of the present invention, the structure is selected from Group 2. In one aspect of the present invention, the structure is selected from Group 3. In one aspect of the present invention, the structure is selected from Group 4. In one aspect of the present invention, the structure is selected from Group 5. In one aspect of the present invention, the structure is selected from Group 6. In one aspect of the present invention, the structure is selected from Group 7. In one aspect of the present invention, the structure is selected from Group 8. In one aspect of the present invention, the structure is selected from Group 9. In one aspect of the present invention, the structure is selected from Group 10. In the above structure, R represents a hydrogen atom or a substituted or unsubstituted aryl group, and at least one of the Rs in each formula is an aryl group to which the condensed polycyclic aromatic hydrocarbon structure is bonded by a single bond or a linking group. For a description of the aromatic ring constituting the aryl group in "substituted or unsubstituted aryl group," refer to the description of the aromatic ring of the hydrocarbon as the core skeleton above. The aryl group is preferably a phenyl group. For a description of the substituents of the aryl group, preferred ranges, and specific examples, refer to the description of substituents in the core skeleton above. For a description of the condensed polycyclic aromatic hydrocarbon structure, preferred ranges, and specific examples, refer to the description of the condensed polycyclic aromatic hydrocarbon structure in the TTA-UC compound above. The condensed polycyclic aromatic hydrocarbon structure is preferably a substituted or unsubstituted anthracenyl group, a substituted or unsubstituted pyrenyl group, or a substituted or unsubstituted perilenyl group. For a description of the linking group, preferred ranges, and specific examples, refer to the description of the linking group introduced between the condensed polycyclic aromatic hydrocarbon structure and the core skeleton above. When there are two or more R groups in a formula, the R groups may be the same or different from each other. One or more hydrogen atoms of the ring skeleton of a multiple resonance condensed polycyclic structure may be substituted with substituents. The substituents may be selected, for example, from substituent group A described below, or from substituent group B described below. In particular, substituents on the ring skeleton of a multiple resonance condensed polycyclic structure are preferably substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, and substituted or unsubstituted alkyl groups. For explanations, preferred ranges, and specific examples of substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, and substituted or unsubstituted alkyl groups as substituents on condensed aromatic rings, refer to the above description of substituted or unsubstituted aryl groups, substituted or unsubstituted heteroaryl groups, and substituted or unsubstituted alkyl groups as substituents on condensed aromatic rings.

[0039] In the above structures, if there is one R in the formula, that R is an aryl group to which two or more condensed polycyclic aromatic hydrocarbon structures are bonded by single bonds or linking groups, and two of these condensed polycyclic aromatic hydrocarbon structures constitute a first and second condensed polycyclic aromatic hydrocarbon structure with a predetermined interbenzene distance. In addition, in structures with multiple Rs in the formula, one of the multiple Rs may be an aryl group to which a condensed polycyclic aromatic hydrocarbon structure is bonded, or two or more of the multiple Rs may be aryl groups to which condensed polycyclic aromatic hydrocarbon structures are bonded. If one R is an aryl group to which a condensed polycyclic aromatic hydrocarbon structure is bonded, that aryl group to which the condensed polycyclic aromatic hydrocarbon structure is bonded is an aryl group to which two or more condensed polycyclic aromatic hydrocarbon structures are bonded by single bonds or linking groups, and two of these condensed polycyclic aromatic hydrocarbon structures constitute a first and second condensed polycyclic aromatic hydrocarbon structure with a predetermined interbenzene distance. If two or more R are aryl groups to which condensed polycyclic aromatic hydrocarbon structures are attached, the number of condensed polycyclic aromatic hydrocarbon structures attached to each aryl group may be one or more, but two of these condensed polycyclic aromatic hydrocarbon structures are first and second condensed polycyclic aromatic hydrocarbon structures with interbenzene distances within a predetermined range. In this case, two condensed polycyclic aromatic hydrocarbon structures attached to the aryl group by single bonds or linking groups may constitute the first and second condensed polycyclic aromatic hydrocarbon structures, or two or more R are aryl groups to which one condensed polycyclic aromatic hydrocarbon structure is attached, and the condensed polycyclic aromatic hydrocarbon structures in two of these R may constitute the first and second condensed polycyclic aromatic hydrocarbon structures, respectively.

[0040] In a preferred embodiment of the present invention, the TTA-UC compound has a multi-resonance condensed polycyclic structure selected from the group consisting of the above structures, wherein at least one of the Rs is an aryl group to which the first and second condensed polycyclic aromatic hydrocarbon structures are bonded by a single bond or a linking group. In a more preferred embodiment of the present invention, the TTA-UC compound has a multi-resonance condensed polycyclic structure selected from the group consisting of the above structures, wherein only one of the Rs is an aryl group to which the first and second condensed polycyclic aromatic hydrocarbon structures are bonded by a single bond or a linking group. In one embodiment of the present invention, the TTA-UC compound is a compound having the above structure with two or more Rs, wherein two or more of the Rs are aryl groups to which the first and second condensed polycyclic aromatic hydrocarbon structures are bonded by a single bond or a linking group. In these embodiments, the aryl groups to which the first and second condensed polycyclic aromatic hydrocarbon structures are linked by single bonds or linking groups are preferably phenyl groups substituted with condensed aromatic groups selected from the group consisting of substituted or unsubstituted anthracenyl groups, substituted or unsubstituted pyrenyl groups, and substituted or unsubstituted perilenyl groups, or phenyl groups substituted with phenyl groups substituted with such condensed aromatic groups. In another preferred embodiment of the present invention, the TTA-UC compound is a compound represented by the above general formula (1), wherein one or more hydrogen atoms of the benzene ring of its core skeleton are substituted with substituents having a multiple resonance condensed polycyclic structure selected from the group consisting of the above structure. In a more preferred embodiment of the present invention, the TTA-UC compound is a compound represented by the above general formula (2), wherein its R 1 ~R 4 At least one of the substituents is selected from the group consisting of the above structures and is a substituent having a multi-resonance condensed polycyclic structure, and in a more preferred embodiment, the TTA-UC compound is a compound represented by general formula (2), and R 1 ~R 4 Only one of them is a substituent having a multi-resonance condensed polycyclic structure selected from the group consisting of the above structures, and in another, more preferred embodiment, the TTA-UC compound is a compound represented by general formula (2), and at least R 2The compound is a substituent having a multi-resonance fused polycyclic structure selected from the group consisting of the above structures. For the explanation of "substituents having a multi-resonance fused polycyclic structure selected from the group consisting of the above structures," the explanation of the above structures can be referred to by substituting one of the Rs, which represents "aryl groups in which the first and second fused polycyclic aromatic hydrocarbon structures are bonded by single bonds or linking groups," for the bond position to the benzene ring in general formulas (1) and (2). In the above structure, the R that is bonded to the benzene ring is not particularly limited, but in a heterofused ring structure having a structure in which a boron atom is bonded to a benzene ring, it is preferable that the R is in the para position relative to the boron atom.

[0041] Specific examples of TTA-UC compounds that can be used in the present invention are given below. However, the TTA-UC compounds that can be used in the present invention should not be interpreted as being limited by these specific examples.

[0042] [ka]

[0043] <Delayed Fluorescence (TADF) Materials> The intramolecular TTA upconversion material of the present invention can be preferably used as a light-emitting material in organic light-emitting devices of TAF systems. That is, by using it in combination with an assist dopant of a delayed fluorescence material (TADF material), an excellent organic light-emitting device of a TAF system can be provided. The delayed fluorescence materials used in combination with the intramolecular TTA upconversion material of the present invention will be described below.

[0044] The delayed fluorescence material used in combination with the intramolecular TTA upconversion material is a delayed fluorescence material that has a lower minimum singlet excitation energy than the intramolecular TTA upconversion material. If a host material is also used, it is preferable that the delayed fluorescence material has a lower minimum singlet excitation energy than the host material. In this invention, a "delayed fluorescence material" is an organic compound that, in its excited state, undergoes a reverse intersystem crossover from an excited triplet state to an excited singlet state, and emits fluorescence (delayed fluorescence) when returning from the excited singlet state to the ground state. In this invention, a delayed fluorescence material is defined as a material that exhibits fluorescence with an emission lifetime of 100 ns (nanoseconds) or more when measured using a fluorescence lifetime measurement system (such as the Hamamatsu Photonics Streak Camera System). A delayed fluorescence material (assist dopant) used in combination with an intramolecular TTA upconversion material is a material capable of emitting delayed fluorescence, but it is not essential that the delayed fluorescence originating from this assist dopant delayed fluorescence material is emitted when used in the organic light-emitting device of this invention. The emission from the assist dopant delayed fluorescence material is preferably less than 10% of the emission from the organic light-emitting device of this invention, and may be, for example, less than 1%, less than 0.1%, less than 0.01%, or below the detection limit. In an organic light-emitting device using a host material, the delayed fluorescence material, which acts as an assist dopant, transitions to the excited singlet state by receiving energy from the excited singlet state of the host material. Alternatively, the delayed fluorescence material, which acts as an assist dopant, may transition to the excited triplet state by receiving energy from the excited triplet state of the host material. The delayed fluorescence material, which acts as an assist dopant, transitions to the excited triplet state by receiving energy from the excited singlet energy and the excited triplet energy difference (ΔE ST Because the ) is small, the assist dopant in the excited triplet state readily crosses back into the assist dopant in the excited singlet state. The assist dopant in the excited singlet state generated by these pathways transfers energy to the intramolecular TTA upconversion material, causing the intramolecular TTA upconversion material to transition to the excited singlet state.

[0045] The delayed fluorescence material, which acts as an assist dopant, has a difference of ΔE between its lowest excitation singlet energy and its lowest excitation triplet energy at 77K. STIt is preferable that the voltage is 0.3 eV or less, more preferably 0.25 eV or less, more preferably 0.2 eV or less, more preferably 0.15 eV or less, even more preferably 0.1 eV or less, even more preferably 0.07 eV or less, even more preferably 0.05 eV or less, even more preferably 0.03 eV or less, and particularly preferably 0.01 eV or less. ΔE ST If the temperature is small, the assist dopant can easily reverse intersystem cross from the excited singlet state to the excited triplet state by absorbing thermal energy, thus functioning as a thermally activated delayed fluorescence material. Thermally activated delayed fluorescence materials can absorb the heat emitted by the device and reverse intersystem cross from the excited triplet state to the excited singlet state relatively easily, and can efficiently contribute that excited triplet energy to luminescence.

[0046] In one preferred embodiment of the present invention, a compound represented by the following general formula (3) is used as an assist dopant, which is a delayed fluorescence material. [ka]

[0047] In general formula (3), R 21 ~R 23 One of them represents a cyano group or a group represented by the following general formula (4), R 21 ~R 23 The remaining two and R 24 and R 25 At least one of them represents a group represented by the following general formula (5), R 21 ~R 25 The remainder represents a hydrogen atom or a substituent (however, the substituent referred to here is not a cyano group, a group represented by general formula (4) below, or a group represented by general formula (5) below). [ka] In general formula (4), L 1 represents a single bond or a divalent linking group, R 31 and R 32Each of the symbols represents an independent hydrogen atom or substituent, and * represents a bond position. [ka] In general formula (5), L 2 represents a single bond or a divalent linking group, R 33 and R 34 Each of the symbols represents an independent hydrogen atom or substituent, and * represents a bond position.

[0048] R 21 ~R 23 Among them, R 21 or R 22 It is preferable that is a cyano group or a group represented by general formula (4). In one preferred embodiment of the present invention, R 22 is a cyano group. In one preferred embodiment of the present invention, R 22 This is a group represented by general formula (4). In one aspect of the present invention, R 21 R is a cyano group or a group represented by general formula (4). In one aspect of the present invention, R 23 R is a cyano group or a group represented by general formula (4). In one aspect of the present invention, R 21 ~R 23 One of them is a cyano group. In one aspect of the present invention, R 21 ~R 23 One of these is the group represented by general formula (4).

[0049] In one preferred embodiment of the present invention, L in general formula (4) 1 It is a single bond. In one aspect of the present invention, L 1 The linking group is a divalent group, preferably a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, more preferably a substituted or unsubstituted arylene group, and even more preferably a substituted or unsubstituted 1,4-phenylene group (with a substituent such as an alkyl group having 1 to 3 carbon atoms). In one aspect of the present invention, R in general formula (4) 31 and R 32Each of these is independently one or more groups selected from the group consisting of alkyl groups (e.g., 1 to 40 carbon atoms), aryl groups (e.g., 6 to 30 carbon atoms), heteroaryl groups (e.g., 5 to 30 ring skeleton constituent atoms), alkenyl groups (e.g., 1 to 40 carbon atoms), and alkynyl groups (e.g., 1 to 40 carbon atoms) (hereinafter these groups are referred to as "substituent group A groups"). In a preferred embodiment of the present invention, R 31 and R 32 Each of these is independently a substituted or unsubstituted aryl group (e.g., having 6 to 30 carbon atoms), and examples of substituents on the aryl group include the groups of substituent group A. In a preferred embodiment of the present invention, R 31 and R 32 They are identical.

[0050] In one preferred embodiment of the present invention, L in general formula (5) 2 It is a single bond. In one aspect of the present invention, L 2 The linking group is a divalent group, preferably a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group, more preferably a substituted or unsubstituted arylene group, and even more preferably a substituted or unsubstituted 1,4-phenylene group (with a substituent such as an alkyl group having 1 to 3 carbon atoms). In one aspect of the present invention, R in general formula (5) 33 and R 34Each of these independently represents a substituted or unsubstituted alkyl group (e.g., 1-40 carbon atoms), a substituted or unsubstituted alkenyl group (e.g., 1-40 carbon atoms), a substituted or unsubstituted aryl group (e.g., 6-30 carbon atoms), or a substituted or unsubstituted heteroaryl group (e.g., 5-30 carbon atoms). Substituents for alkyl groups, alkenyl groups, aryl groups, and heteroaryl groups as used here include hydroxyl groups, halogen atoms (e.g., fluorine, chlorine, bromine, iodine atoms), alkyl groups (e.g., 1-40 carbon atoms), alkoxy groups (e.g., 1-40 carbon atoms), alkylthio groups (e.g., 1-40 carbon atoms), aryl groups (e.g., 6-30 carbon atoms), aryloxy groups (e.g., 6-30 carbon atoms), arylthio groups (e.g., 6-30 carbon atoms), heteroaryl groups (e.g., 5-30 carbon atoms in the ring skeleton), heteroaryloxy groups (e.g., 5-30 carbon atoms in the ring skeleton), and heteroarylthio groups. Examples of groups include one or more groups selected from the group consisting of oxy groups (e.g., 5-30 atoms in the ring skeleton), acyl groups (e.g., 1-40 carbon atoms), alkenyl groups (e.g., 1-40 carbon atoms), alkynyl groups (e.g., 1-40 carbon atoms), alkoxycarbonyl groups (e.g., 1-40 carbon atoms), aryloxycarbonyl groups (e.g., 1-40 carbon atoms), heteroaryloxycarbonyl groups (e.g., 1-40 carbon atoms), silyl groups (e.g., trialkylsilyl groups with 1-40 carbon atoms), nitro groups, and cyano groups (hereinafter, these groups will be referred to as "substituent group B groups"). R 33 and R 34 These may be linked to each other by single bonds or linking groups to form a cyclic structure. In particular, R 33 and R 34 If the group is an aryl group, it is preferable that they are bonded to each other via single bonds or linking groups to form a cyclic structure. The linking groups referred to here are -O-, -S-, and -N(R 35 )-,-C(R 36 )(R 37 We can list -, -C(=O)-, -O-, -S-, -N(R 35 )-,-C(R 36 )(R 37 )- is preferred, -O-, -S-, -N(R 35)- is more preferable. R 35 ~R 37 Each of these independently represents a hydrogen atom or a substituent. The substituent can be selected from substituent group A above or from substituent group B below, and preferably is one group or a combination of two or more groups selected from the group consisting of alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 14 carbon atoms.

[0051] The group represented by general formula (5) is preferably the group represented by general formula (6) below. [ka]

[0052] The compound represented by general formula (6) is more preferably a compound represented by any of the following general formulas (7) to (12). [ka]

[0053] In general formulas (6) to (12), L 11 and L 21 ~L 26 L represents a single bond or a divalent linking group. 11 and L 21 ~L 26 For an explanation and preferred range, see L above. 2 You can refer to the explanation and preferred range. In general formulas (6) to (12), R 41 ~R 110 Each of these independently represents a hydrogen atom or a substituent. 41 and R 42 , R 42 and R 43 , R 43 and R 44 , R 44 and R 45 , R 45 and R 46 , R 46 and R 47 , R 47 and R 48 , R51 and R 52 , R 52 and R 53 , R 53 and R 54 , R 54 and R 55 , R 55 and R 56 , R 56 and R 57 , R 57 and R 58 , R 58 and R 59 , R 59 and R 60 , R 61 and R 62 , R 62 and R 63 , R 63 and R 64 , R 65 and R 66 , R 66 and R 67 , R 67 and R 68 , R 68 and R 69 , R 69 and R 70 , R 72 and R 73 , R 73 and R 74 , R 74 and R 75 , R 75 and R 76 , R 76 and R 77 , R 77 and R 78 , R 78 and R 79 , R 79 and R 80 , R 81 and R 82 , R 82 and R 83 , R 83 and R 84 , R 84 and R 85 , R 86 and R 87 , R 87 and R 88 , R 88 and R 89 , R 89 and R 90 , R 91and R 92 , R 93 and R 94 , R 94 and R 95 , R 95 and R 96 , R 96 and R 97 , R 97 and R 98 , R 99 and R 100 , R 101 and R 102 , R 102 and R 103 , R 103 and R 104 , R 104 and R 105 , R 105 and R 106 , R 107 and R 108 , R 108 and R 109 , R 109 and R 110 These rings may bond to each other to form a cyclic structure. The cyclic structure formed by the bonding may be an aromatic ring or an antilipid ring, and may contain heteroatoms. Furthermore, the cyclic structure may be a fused ring of two or more rings. The heteroatoms referred to here are preferably selected from the group consisting of nitrogen atoms, oxygen atoms, and sulfur atoms. Examples of the cyclic structures formed include benzene rings, naphthalene rings, pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, pyrrole rings, imidazole rings, pyrazole rings, imidazoline rings, oxazole rings, isoxazole rings, thiazole rings, isothiazole rings, cyclohexadiene rings, cyclohexene rings, cyclopentaene rings, cycloheptatriene rings, cycloheptadiene rings, cycloheptaene rings, furan rings, thiophene rings, naphthyridine rings, quinoxaline rings, and quinoline rings. For example, a ring formed by the fusion of multiple rings, such as a phenanthrene ring or a triphenylene ring, may also be formed. The number of rings in the group represented by general formula (6) may be selected from 3 to 5, or from 5 to 7. The number of rings in the groups represented by general formulas (7) to (12) may be selected from 5 to 7, or it may be 5. R 41 ~R110 Examples of substituents that can be adopted include the groups of substituent group B above, preferably an unsubstituted alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 10 carbon atoms that may be substituted with an unsubstituted alkyl group having 1 to 10 carbon atoms. In a preferred embodiment of the present invention, R 41 ~R 110 R is a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. In a preferred embodiment of the present invention, R 41 ~R 110 R is a hydrogen atom or an unsubstituted aryl group having 6 to 10 carbon atoms. In a preferred embodiment of the present invention, R 41 ~R 110 It is all hydrogen atoms. R in general formulas (6) to (12) 41 ~R 110 The carbon atoms to which the compound is bonded (the carbon atoms forming the ring skeleton) may each be independently substituted with a nitrogen atom. That is, the CR in general formulas (6) to (12) 41 ~CR 110 Each of these may be independently substituted with N. The number of nitrogen atoms substituted is preferably 0 to 4, and more preferably 1 to 2, among the groups represented by general formulas (6) to (12). In one embodiment of the present invention, the number of nitrogen atoms substituted is 0. Furthermore, if two or more are substituted with nitrogen atoms, it is preferable that the number of nitrogen atoms substituted in one ring is 1. In general formulas (6) to (12), X 1 ~X 6 X represents an oxygen atom, a sulfur atom, or NR. In one aspect of the present invention, X 1 ~X 6 X is an oxygen atom. In one aspect of the present invention, X 1 ~X 6 is a sulfur atom. In one aspect of the present invention, X 1 ~X 6NR is NR. R represents a hydrogen atom or a substituent, and is preferably a substituent. Examples of substituents include those selected from the substituent group A above. For example, an unsubstituted phenyl group or a phenyl group substituted with one or more groups selected from the group consisting of alkyl groups and aryl groups can be preferably used. In general formulas (6) to (12), * represents the bonding position.

[0054] The following are preferred compounds that can be used as assist dopants or delayed fluorescence materials. In the structural formulas of the following example compounds, t-Bu represents a tert-butyl group. [ka] JPEG2023074478000022.jpg239170JPEG2023074478000023.jpg208170JPEG2023074478000024.jpg201170JPEG2023074478000025.jpg22415 6JPEG2023074478000026.jpg185170JPEG2023074478000027.jpg229170JPEG2023074478000028.jpg226154JPEG2023074478000029.jpg46170

[0055] In addition to the above, other known delayed fluorescence materials can be used as assist dopants. Furthermore, even unknown delayed fluorescence materials can be used. As an assist dopant, a delayed fluorescence material is used, paragraphs 0008-0048 and 0095-0133 of WO2013 / 154064, paragraphs 0007-0047 and 0073-0085 of WO2013 / 011954, paragraphs 0007-0033 and 0059-0066 of WO2013 / 011955, and paragraphs 0007-0033 and 0059-0066 of WO2013 / 081088. Paragraphs 0008-0071 and 0118-0133 of Japanese Patent Publication No. 2013-256490, paragraphs 0009-0046 and 0093-0134 of Japanese Patent Publication No. 2013-116975, paragraphs 0008-0020 and 0038-0040 of Japanese Patent Publication No. WO2013 / 133359, paragraphs 0007-0032 and 0079-0084 of Japanese Patent Publication No. WO2013 / 161437 Paragraphs 0008-0054 and 0101-0121 of Japanese Patent Publication No. 2014-9352, paragraphs 0007-0041 and 0060-0069 of Japanese Patent Publication No. 2014-9224, paragraphs 0008-0048 and 0067-0076 of Japanese Patent Publication No. 2017-119663, paragraphs 0013-0025 of Japanese Patent Publication No. 2017-119664, and Japanese Patent Publication No. 20 Examples of compounds that include compounds contained in the general formulas described in paragraphs 0012-0025 of Japanese Patent Publication No. 17-222623, paragraphs 0010-0050 of Japanese Patent Application Publication No. 2017-226838, paragraphs 0012-0043 of Japanese Patent Application Publication No. 2018-100411, and paragraphs 0016-0044 of Japanese Patent Application Publication No. WO2018 / 047853, particularly exemplary compounds that emit delayed fluorescence.Also, Japanese Patent Publication No. 2013-253121, WO2013 / 133359, WO2014 / 034535, WO2014 / 115743, WO2014 / 122895, WO2014 / 126200, WO2014 / 136758, WO2014 / 133121, WO2014 / 136860, WO2014 / 196585, WO2014 / 189122, WO2014 / 168101, WO2015 / 00858 0 publication, WO2014 / 203840 publication, WO2015 / 002213 publication, WO2015 / 016200 publication, WO2015 / 019725 publication, Publications WO2015 / 072470, WO2015 / 108049, WO2015 / 080182, WO2015 / 072537, WO2015 / 080183, JP 2015-129240, WO2015 / 129714, WO2015 / 129715, WO2015 / 133 Light-emitting materials that emit delayed fluorescence, as described in Publication No. 501, WO2015 / 136880, WO2015 / 137244, WO2015 / 137202, WO2015 / 137136, WO2015 / 146541, and WO2015 / 159541, can also be used. The above publications mentioned in this paragraph are incorporated herein by reference as part of this specification.

[0056] The assist dopant, which is a delayed fluorescence material, preferably does not contain metal atoms. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms can be selected. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms can be selected. For example, a compound consisting of carbon atoms, hydrogen atoms, and nitrogen atoms can be selected.

[0057] <Host Materials> The light-emitting layer constituting the organic light-emitting element of the TAF system may also use a host material in addition to the intramolecular TTA upconversion material, which is the light-emitting material, and the delayed fluorescence material (TADF material), which is the assist dopant. The host material should be one that has a lower minimum excitation singlet energy than the intramolecular TTA upconversion material or the delayed fluorescence material. The host material is preferably an organic compound that has hole transport ability and electron transport ability, prevents the emission from becoming longer wavelengths, and has a high glass transition temperature. In a preferred embodiment of the present invention, the host material is selected from compounds that do not emit delayed fluorescence. The emission from the host material is preferably less than 1% of the emission from the organic light-emitting element of the present invention, more preferably less than 0.1%, and may be, for example, less than 0.01% or below the detection limit. The host material preferably does not contain metal atoms. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms can be selected as the host material. The following are some preferred compounds that can be used as host materials.

[0058] [ka] JPEG2023074478000031.jpg241170JPEG2023074478000032.jpg80170

[0059] <Organic light-emitting element> The organic light-emitting device of the present invention includes the intramolecular TTA upconversion material of the present invention. Preferably, the organic light-emitting device of the present invention includes the intramolecular TTA upconversion material of the present invention in the light-emitting layer. Hereinafter, an embodiment of the organic light-emitting device of the present invention, which includes the intramolecular TTA upconversion material in the light-emitting layer, will be described. (Emitting layer) The light-emitting layer of the organic light-emitting device of the present invention may consist of a first light-emitting composition comprising the intramolecular TTA upconversion material and host material of the present invention, or it may consist of a second light-emitting composition comprising the intramolecular TTA upconversion material, a delayed fluorescence material which is an assist dopant, and a host material of the present invention. The delayed fluorescence material of the second light-emitting composition may be one of the delayed fluorescence materials described in the <Delayed Fluorescence Material (TADF Material)> section above, and the host material of the second light-emitting composition may be one of the host materials described in the <Host Material> section above. For the host material of the first light-emitting composition, a host material with a lower minimum excitation singlet energy higher than that of the intramolecular TTA upconversion material may be selected and used. In a preferred embodiment of the present invention, the light-emitting layer does not contain any compounds or metal elements that transfer charge or energy other than the intramolecular TTA upconversion material, the delayed fluorescence material which is an assist dopant, and the host material. Furthermore, the light-emitting layer may consist only of the intramolecular TTA upconversion material and the host material, or it may consist only of the TTA upconversion material, the delayed fluorescence material which is an assist dopant, and the host material. Furthermore, the light-emitting layer may also be composed solely of compounds consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, boron atoms, oxygen atoms, sulfur atoms, and fluorine atoms. For example, the light-emitting layer may be composed solely of compounds consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, boron atoms, oxygen atoms, and fluorine atoms. In a preferred embodiment of the present invention, the light-emitting layer contains carbon atoms, hydrogen atoms, nitrogen atoms, boron atoms, oxygen atoms, and fluorine atoms, and more preferably does not contain any other elements.

[0060] The luminescent layer may be formed by a wet process or by a dry process using a first luminescent composition comprising an intramolecular TTA upconversion material and a host material, or a second luminescent composition comprising an intramolecular TTA upconversion material, a delayed fluorescence material which is an assist dopant, and a host material. In the wet process, a solution containing the luminescent composition is applied to a surface, and after the solvent is removed, a luminescent layer is formed. Examples of wet processes include, but are not limited to, spin coating, slit coating, inkjet (spray) printing, gravure printing, offset printing, and flexographic printing. In the wet process, an appropriate organic solvent capable of dissolving the luminescent composition is selected and used. In some embodiments, substituents (e.g., alkyl groups) that increase the solubility in organic solvents can be introduced into the compounds contained in the luminescent composition.

[0061] As a dry process, vacuum deposition can be preferably employed. When using vacuum deposition, each compound constituting the light-emitting layer may be co-deposited from an individual deposition source, or all compounds may be co-deposited from a single deposition source. When using a single deposition source, a mixed powder of all compound powders may be used, a compressed molded body made by compressing the mixed powder may be used, or a mixture obtained by heating, melting, mixing, and then cooling each compound may be used. In one embodiment, by performing co-deposition under conditions where the deposition rates (weight loss rates) of multiple compounds contained in a single deposition source are the same or nearly the same, a light-emitting layer with a composition ratio corresponding to the composition ratio of multiple compounds contained in the deposition source can be formed. By mixing multiple compounds in the same composition ratio as the composition ratio of the formed light-emitting layer to form a deposition source, a light-emitting layer with a desired composition ratio can be easily formed. In one embodiment, the temperature at which each co-deposited compound has the same weight loss rate can be identified, and that temperature can be adopted as the temperature during co-deposition. When the luminescent layer is formed by vapor deposition, the molecular weights of the intramolecular TTA upconversion material, the delayed fluorescence material acting as an assist dopant, and the host material are preferably 1500 or less, more preferably 1200 or less, even more preferably 1000 or less, and even more preferably 900 or less. The lower limit of the molecular weight may be, for example, 200, 400, or 600.

[0062] (Layer structure of organic light-emitting element) By forming a light-emitting layer consisting of a first light-emitting composition containing an intramolecular TTA upconversion material and a host material, or a second light-emitting composition containing an intramolecular TTA upconversion material, a delayed fluorescence material which is an assist dopant, and a host material, it is possible to provide excellent organic light-emitting elements such as organic photoluminescent elements (organic PL elements) and organic electroluminescent elements (organic EL elements). The thickness of the light-emitting layer can be, for example, 1-15 nm, 2-10 nm, or 3-7 nm. Organic photoluminescent elements have a structure in which at least a light-emitting layer is formed on a substrate. Organic electroluminescent elements have 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 only of a light-emitting layer, or it may have one or more organic layers in addition to the light-emitting layer. Examples of other such organic layers include hole transport layers, hole injection layers, electron barrier layers, electron injection layers, electron transport layers, and exciton barrier layers. 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.

[0063] The descriptions of use, devices, displays, screens, etc., in paragraphs

[0141] to

[0169] and

[0192] to

[0242] of US2020 / 0168814A1 are incorporated herein by reference as part of this specification and constitute a description of the present invention.

[0064] In one embodiment of the present invention, the following compounds can be preferably used as electron blocking materials. [ka]

[0065] In one embodiment of the present invention, the following compounds can be preferably used as hole-blocking materials. [ka]

[0066] Examples of preferable compounds that can be used as a hole injection material for an organic electroluminescence device are given below.

Chem.

[0067] Next, examples of preferable compounds that can be used as an electron injection material for an organic electroluminescence device are given.

Chem.

[0068] Furthermore, examples of preferable compounds as materials that can be added to each organic layer of an organic electroluminescence device are given. For example, addition as a stabilizing material etc. can be considered.

[0069]

Chem.

Examples

[0070] The features of the present invention are further specifically described below by giving synthesis examples and examples. The materials, treatment contents, treatment procedures, etc. shown below can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. The measurement of the photoluminescence quantum yield of the light-emitting layer was performed using an absolute PL quantum yield measurement device (Quantaurus-QY C11347-11: manufactured by Hamamatsu Photonics K.K.), and the evaluation of the device characteristics was performed using a spectro-radiance meter (CS-2000A: manufactured by Konica Minolta Inc.), a streak camera (C4334: manufactured by Hamamatsu Photonics K.K.), and a pulse generator (8114A: manufactured by Agilent Technologies).

[0071] (Synthesis Example 1) Synthesis of Compound 1

Chem.

[0072] 1,2-Diiodobenzene (0.56 g, 1.7 mmol), 2-Anthraceneboronic acid (1.3 g, 4.3 mmol), tetrakis(triphenylphosphine)palladium (0) (230 mg, 0.2 mmol), and potassium carbonate (1.38 g, 35 mmol) were dissolved in a degassed toluene / ethanol / water mixed solvent (128 mL) and stirred at 80°C for 18 hours under a nitrogen atmosphere. After cooling, the reaction mixture was filtered to remove the precipitate, washed with saturated brine, and extracted with dichloromethane solution. The recovered organic extract was dried over sodium sulfate, and the solvent was removed to obtain a pale yellow solid. The obtained solid was purified by silica gel column chromatography using a hexane:dichloromethane = 4:1 mixed solvent as the eluent, and further purified by vacuum sublimation to obtain compound 1 (310 mg, 0.72 mmol, yield 42.5%) as a pale yellow solid. 1 H-NMR (500MHz, CDCl3) δ = 8.31-8.29 (d, J = 15 Hz, 4H), 8.00 (s, 2H), 7.95 -7.93 (m, J = 10 Hz, 4H), 7.69 -7.65 (m, J = 20 Hz, 4H), 7.55 -7.53 (m, J = 10 Hz, 2H), 7.43 -7.41 (m, J = 10 Hz, 4H), 7.19 -7.17 (d, J = 10 Hz, 2H); 13 C-NMR (125MHz, CDCl3) δ = 140.56, 138.70, 131.83, 131.75, 131.69, 131.04, 130.45, 138.42, 128.16, 128.13, 128.09, 127.88, 127.45, 126.31, 125.90, 125.36, 125.29; Anal. Calcd for C 34 H 22 : C 94.85, H 5.15, N 0.0, found: C 94.88, H 5.02, N 0.05.

[0073] (Synthesis of comparative compounds) Comparative compounds 1-4 below were synthesized using the same procedure as in Synthesis Example 1.

[0074] [ka]

[0075] (Synthesis Example 2) Synthesis of Compound 2 [ka]

[0076] Intermediate 1 was obtained in 70% yield by dissolving 2-anthraceneboronic acid, 4-bromo-1,2-diiodobenzene, tetrakis(triphenylphosphine)palladium(0), and potassium carbonate in a mixed solvent of toluene, ethanol, and water, and carrying out the Suzuki-Miyaura coupling reaction by stirring at 80°C for 24 hours.

[0077] [ka]

[0078] Intermediate 2 was synthesized according to the method described in CCS Chem. 2022, 4, 2065-2079. Intermediate 2, intermediate 1, tetrakis(triphenylphosphine)palladium(0), and potassium carbonate were dissolved in a mixed solvent of toluene, ethanol, and water, and the Suzuki-Miyaura coupling reaction was carried out by stirring at 80°C for 24 hours to obtain compound 2 in 86% yield.

[0079] Table 1 shows the shortest distance, distance between centers of gravity, and dihedral angle between the two anthracene structures of Compound 1 and Comparative Compounds 1 to 4. Here, as shown in Fig. 1, the shortest distance between the two anthracene structures is the distance between the centers of the combination of benzene rings with the closest positions among the benzene rings constituting one anthracene ring and the benzene rings constituting the other anthracene ring in the planar structure. The distance between the centers of gravity of the two anthracene structures is the distance between the centers of the benzene ring at the center of one anthracene ring and the benzene ring at the center of the other anthracene ring. The dihedral angle is the angle formed by the planes constituted by one anthracene ring and the plane constituted by the other anthracene ring. All were measured by three-dimensional molecular structure analysis using X-ray single crystal structure analysis.

[0080]

Table 1

[0081] (Example 1) Fabrication and Evaluation of an Organic Electroluminescence Device Using Compound 1 On a glass substrate on which an anode made of indium tin oxide (ITO) with a thickness of 100 nm was formed, each thin film was laminated by vacuum evaporation at a vacuum degree of 3.0×10 -4 Pa or less. First, HATCN was formed on the ITO to a thickness of 10 nm, and on top of that, TrisPCz was formed to a thickness of 30 nm. Next, Compound 1 and mCBP-CN were co-evaporated from different evaporation sources to form a layer with a thickness of 15 nm as the light-emitting layer. At this time, the concentration of Compound 1 was 10 wt%. Next, TPBi was formed to a thickness of 40 nm. Subsequently, LiF was formed to a thickness of 0.8 nm, and further, aluminum (Al) was evaporated to a thickness of 60 nm to form a cathode, resulting in an organic electroluminescence device (EL device 1a).

[0082] An organic electroluminescence device (EL device 1b) was fabricated in the same procedure except that the concentration of Compound 1 in the light-emitting layer was changed to 20 wt%.

[0083] (Comparative Examples 1-4) Fabrication of Organic EL Devices using Comparative Compounds 1-4 Except for using comparative compounds 1-4 instead of compound 1, each organic electroluminescent element (comparative EL elements 1-4) was fabricated using the same procedure as EL element 1a.

[0084] For each fabricated EL element, a pulse voltage with a repetition frequency of 200 Hz was applied for 10 μs, and then the transient curve of the luminescence intensity (transient EL curve) was measured. Here, the current density when the pulse voltage was applied was 250 mA / cm². 2 The measured transient EL curve and mathematical model were used to calculate the exciton utilization efficiency (η). r ) was derived. Here, the exciton utilization efficiency (η r η represents the proportion of excitons generated by current excitation that are used for luminescence. Excitons that can be used for luminescence include both singlet excitons directly generated by carrier recombination and singlet excitons generated by TTA upconversion, but the proportion of singlet excitons among the excitons directly generated by carrier recombination is 25% according to spin statistics. Therefore, η r A value exceeding 25% indicates that TTA upconversion occurred on the compound molecule, and the resulting singlet excitons were utilized for UC emission. Below is the exciton utilization efficiency (η) used in this example. r The derivation method for ) will be explained. First, Figure 2 shows the measurement results of the transient EL curves of EL elements 1a and 1b, and the fitting curves for the TTA model and the Trap Charge Recombination (Trap RC) model. Here, the TTA model is defined as the time change of EL intensity (I) originating from TTA upconversion. EL (t)) is expressed by the mathematical model shown in equation (1) below, and the Trap RC model shows the time change of EL intensity (I) originating from trap charge recombination. EL (t)) is represented by the mathematical model shown in equation (2) below. Note that trap charge recombination is a phenomenon in which charges accumulated in the organic layer when a pulse voltage is applied recombine after the voltage is turned off, resulting in light emission.

[0085]

number

[0086] As shown in Figure 2, the transient EL curves measured for EL elements 1a and 1b were in close agreement. In both transient EL curves, a rapid fluorescence decay immediately after voltage cutoff (immediate fluorescence decay) and two types of gradual delayed fluorescence decay were observed. Here, immediate fluorescence decay corresponds to the decay of fluorescence emission directly caused by carrier recombination. On the other hand, of the two types of delayed fluorescence decay, the first delayed fluorescence decay was found to be in good fit with the fitting curve of the TTA model, and therefore corresponds to the decay of UC emission originating from TTA upconversion. The second delayed fluorescence decay was found to be in good fit with the scaling index m following a power law of 1 to 2, and therefore corresponds to the decay of emission originating from trap charge recombination. Based on these analysis results, by analyzing the transient EL curve using the TTA model, the EL intensity ratio (I) of fluorescence directly caused by carrier recombination and UC light due to TTA upconversion was determined. EL (Delayed) / I EL (Prompt)) was estimated. Here, I EL (Delayed) / I EL (Prompt) is the exciton utilization efficiency (η r ) and the following equation (3) are related. Therefore, by substituting the estimated EL intensity ratio into equation (3) and calculating, η r This is required.

[0087]

number

[0088] As a result of this calculation, the exciton utilization efficiency (η) of EL elements 1a and 1b r The exciton utilization efficiency (η) was 40%, which corresponds to the theoretical maximum efficiency of the TTA-UC type device, and far exceeded the probability of singlet exciton generation directly caused by carrier recombination (25%). rThe calculated value of ) was in agreement with the exciton utilization efficiency obtained using the following equation (4) from the measured maximum external quantum efficiency (1.4%) of EL element 1a. In the calculation of equation (4), the PLQY (photoluminescence quantum yield) of 17.2%, measured for the light-emitting layer, was substituted, and the carrier balance factor was assumed to be 100% and the light extraction efficiency 20%, and these values ​​were substituted into each term.

[0089]

number

[0090] From these derivation results, it was confirmed that TTA upconversion indeed occurs when compound 1 is electrically excited, resulting in UC emission. Furthermore, since the luminescence layer formed in this example has a low concentration of compound 1 (10% or 20% by weight), it is thought that intermolecular TTA upconversion is suppressed. Therefore, it was inferred that the UC emission observed here originated from TTA upconversion that occurred within the compound 1 molecule. On the other hand, for EL elements (comparative EL elements 1-4) using comparative compounds 1-4 in which the shortest distance between anthracene structures exceeds 5 Å, the exciton utilization efficiency (η) was calculated using the same derivation method. r When we calculated η, r This value was significantly lower compared to EL elements 1a and 1b. From the above, it was confirmed that compounds having two or more condensed polycyclic aromatic hydrocarbon structures, such as anthracene structures, where the distance between the benzene rings of two of these structures is within the range of 4.5 to 5.0 Å, are useful as intramolecular TTA upconversion materials. Furthermore, it was found that a distance between the centroids of the two condensed polycyclic aromatic hydrocarbon structures of less than 8 Å is preferable.

[0091] (Example 2) Fabrication and evaluation of an organic electroluminescent device using compound 2 Each thin film is deposited onto a glass substrate with an anode made of indium tin oxide (ITO) with a thickness of 100 nm using vacuum deposition at a vacuum level of 5.0 × 10⁻⁶. -4 Layers were stacked at a density of Pa or less. First, HATCN was formed to a thickness of 10 nm on ITO, and then TrisPCz was formed to a thickness of 20 nm on top of it. Next, compound 2 and mCBP were co-deposited from different deposition sources to form a 20 nm thick layer which served as the light-emitting layer. At this time, the concentration of compound 2 was 3% by weight. Next, TPBi was formed to a thickness of 40 nm. Subsequently, lithium fluoride (LiF) was formed to a thickness of 0.8 nm, and then aluminum (Al) was deposited to a thickness of 70 nm to form the cathode, thus creating an organic electroluminescent element (EL element 2).

[0092] 1 mA / cm 2 , 10mA / cm 2 or 100mA / cm 2 Figure 3 shows the emission spectrum of EL element 2 measured at the given current density. The full width at half maximum (FWHM) of the emission peak was 28 nm, confirming that the emission bandwidth was narrowed by introducing a multi-resonance condensed polyring structure. Furthermore, the transient EL curve of EL element 2 was measured after applying a pulse voltage of 11.5 V for 100 μs. The current density during pulse voltage application was 200 mA / cm². 2 The measured transient EL curve and its fitting curves using the TTA model and Trap RC model are shown in Figure 4. As shown in Figure 4, the transient EL curve of EL element 2 also shows delayed fluorescence decay that can be approximated by the fitting curve of the TTA model, and we were able to observe UC emission due to intramolecular TTA upconversion.

[0093] [ka] [Industrial applicability]

[0094] The intramolecular TTA upconversion material of the present invention exhibits TTA upconversion in the solid state, enabling the construction of a solid-state light-emitting layer that generates high-energy light through TTA upconversion. Furthermore, the intramolecular TTA upconversion material of the present invention exhibits high TTA-UC efficiency even at low concentrations, thus achieving both high emission quantum yield and high TTA-UC efficiency. Therefore, the TTA upconversion material of the present invention can be effectively used as a material for the light-emitting layer of a TTA-UC type organic light-emitting device. For this reason, the present invention has high industrial applicability.

Claims

1. A solid-state intramolecular TTA upconversion material comprising a compound having two or more fused polycyclic aromatic hydrocarbon structures, the distance between the benzene rings of any two of the fused polycyclic aromatic hydrocarbon structures being within a range of 4.5 to 5.0 Å.

2. 2. The intramolecular TTA upconversion material according to claim 1, wherein the distance between the benzene rings is in the range of 4.5 to 4.8 Å.

3. 2. The intramolecular TTA upconversion material according to claim 1, wherein the fused polycyclic aromatic hydrocarbon structure has a structure in which 2 to 4 benzene rings are fused.

4. 2. The intramolecular TTA upconversion material of claim 1, wherein the fused polycyclic aromatic hydrocarbon structure comprises a fused aromatic group composed of a fused aromatic ring selected from the group consisting of a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a triphenylene ring, a chrysene ring, and a tetracene ring.

5. 2. The intramolecular TTA upconversion material of claim 1, wherein the two fused polycyclic aromatic hydrocarbon structures are identical.

6. 2. The intramolecular TTA upconversion material of claim 1, wherein the compound further comprises a multi-resonant fused polycyclic structure.

7. 2. The intramolecular TTA upconversion material according to claim 1, wherein the compound has a structure in which the two fused polycyclic aromatic hydrocarbon structures are bonded to a benzene ring.

8. 8. The intramolecular TTA upconversion material of claim 7, wherein the two fused polycyclic aromatic hydrocarbon structures are bonded to the 1- and 2-positions of the benzene ring, respectively.

9. 8. The intramolecular TTA upconversion material of claim 7, wherein the two fused polycyclic aromatic hydrocarbon structures are bonded to the 1- and 2-positions of the benzene ring via 1,4-phenylene groups, respectively.

10. 8. The intramolecular TTA upconversion material of claim 7, wherein the benzene ring is bonded to a multi-resonant fused polycyclic structure.

11. 2. The intramolecular TTA upconversion material according to claim 1, wherein the compound is a compound represented by the following general formula (2): 【Chemical 1】 [In the general formula (2), Ar １ and Ar ２ each independently represents a condensed polycyclic aromatic hydrocarbon structure, and the distance between the benzene rings of the two condensed polycyclic aromatic hydrocarbon structures is 4.5 to 5.0 Å. １ and L ２ each independently represents a single bond, a substituted or unsubstituted arylene group, or a substituted or unsubstituted heteroarylene group; R １ ~R ４ R each independently represents a hydrogen atom or a substituent. １ and R ２ , R ２ and R ３ , R ３ and R ４ may be bonded to each other to form a benzene ring.

12. R in the general formula (2) １ ~R ４ 12. The intramolecular TTA upconversion material according to claim 11, wherein any one of the following is a substituent having a multi-resonant fused polycyclic structure.

13. R in the general formula (2) ２ The intramolecular TTA upconversion material according to claim 11 , wherein is a substituent having a multi-resonant fused polycyclic structure.

14. 2. The intramolecular TTA upconversion material according to claim 1, wherein the compound has a multi-resonant fused polycyclic structure represented by the following general formula (A) or (B): 【Chemistry 2】 [In the general formula (A), X １ represents a boron atom, C═O or C═S. ａ ~R ｉ each independently represents a hydrogen atom, a deuterium atom, or a substituent. ａ ~R ｉ At least one of R is an aryl group to which a condensed polycyclic aromatic hydrocarbon structure is bonded via a single bond or a linking group. ａ and R ｂ , R ｂ and R ｃ , R ｃ and R ｄ , R ｄ and R ｅ , R ｆ and R ｇ , R ｇ and R ｈ , R ｈ and R ｉ , R ｉ and R ａ may be bonded to each other to form a cyclic structure. １ is a boron atom, R ｅ and X １ , X １ and R ｆ are bonded to each other and have X as ring skeleton constituent atoms. １ In addition, a ring structure containing no heteroatom may be formed. In general formula (B), X represents a boron atom, a nitrogen atom, Si—R, P═O, or P═S. １ and Y ２ each independently represents a boron atom, a nitrogen atom, an oxygen atom, a sulfur atom, C═O, C═S, SO ２ where X is Y １ and Y ２ is different from X. R represents a substituted or unsubstituted aryl group, or a substituted or unsubstituted alkyl group. R ｊ ~R ｔ each independently represents a hydrogen atom, a deuterium atom, or a substituent. ｊ ~R ｔ At least one of R is an aryl group to which a condensed polycyclic aromatic hydrocarbon structure is bonded via a single bond or a linking group. ｊ and R ｋ , R ｋ and R ｌ , R ｌ and R ｍ , R ｍ and R ｎ , R ｎ and R ｏ , R ｏ and R ｐ , R ｐ and R ｑ , R ｒ and R ｓ , R ｓ and R ｔ may be bonded to each other to form a cyclic structure. １ is a nitrogen atom or a boron atom, R ｔ and Y １ , Y １ and R ｊ may be bonded to each other to form a cyclic structure. ２ is a nitrogen atom or a boron atom, R ｑ and Y ２ , Y ２ and R ｒ may be bonded to each other to form a cyclic structure.

15. An organic light-emitting device comprising the intramolecular TTA upconversion material according to any one of claims 1 to 14.

16. An organic light-emitting device having a light-emitting layer comprising the intramolecular TTA upconversion material according to any one of claims 1 to 14 and a host material.

17. An organic light-emitting device having an emitting layer containing the intramolecular TTA upconversion material according to any one of claims 1 to 14, a delayed fluorescent material, and a host material.

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