Compound, light-emitting material, and light-emitting device

Abstract

Compounds represented by the general formula below are useful as light-emitting materials. In the formula, two of R1 through R5 are aromatic hydrocarbon cyclic groups or nitrogen-atom-comprising aromatic heterocyclic groups, and three of R1 through R5 are groups having a donor property, of which at least one is a benzofuran-fused carbazolyl-9-yl group.

Description

Technical Field

[0001] The present invention relates to a compound useful as a light-emitting material and a light-emitting device using the same.

Background Art

[0002] Research has been actively conducted to improve the luminous efficiency of light-emitting devices such as organic electroluminescence devices (organic EL devices). In particular, various efforts have been made to improve the luminous efficiency by newly developing and combining an electron transport material, a hole transport material, a light-emitting material, etc. that constitute an organic electroluminescence device. Among them, research on organic electroluminescence devices using a delayed fluorescence material can also be seen.

[0003] A delayed fluorescence material is a material that emits fluorescence when returning from the excited singlet state to the ground state after generating an inverse intersystem crossing from the excited triplet state to the excited singlet state in the excited state. Fluorescence by such a path is observed later than fluorescence from the excited singlet state directly generated from the ground state (ordinary fluorescence), and thus is called delayed fluorescence. Here, for example, when a luminescent compound is excited by carrier injection, the generation probabilities of the excited singlet state and the excited triplet state are statistically 25%:75%. Therefore, there is a limit to improving the luminous efficiency only with fluorescence directly generated from the excited singlet state. On the other hand, in a delayed fluorescence material, not only the excited singlet state but also the excited triplet state can be used for fluorescence emission through the above-mentioned inverse intersystem crossing path, so that a higher luminous efficiency can be obtained compared with ordinary fluorescence materials.

[0004] Since such a principle was revealed, various studies have led to the discovery of various delayed fluorescence materials. However, just because a material emits delayed fluorescence does not immediately mean it is useful as a luminescent material. Among the delayed fluorescence materials, there are those in which reverse intersystem crossing is relatively unlikely to occur, and those with a long lifetime of delayed fluorescence. There are also those in which excitons accumulate in the high current density region, resulting in a decrease in luminescence efficiency, or those that rapidly deteriorate when driven continuously for a long time. Therefore, the fact is that there are extremely many delayed fluorescence materials that have room for improvement in terms of practicality. For this reason, it has been pointed out that there are problems even in benzonitrile-based compounds known as delayed fluorescence materials. For example, although 2CzPN having the following structure is a material that emits delayed fluorescence, it has problems such as low luminescence efficiency and a significant decrease in luminescence efficiency in the high current density region (see Non-Patent Document 1).

[0005] [Chemical formula] [Prior Art Documents] [Non-Patent Documents]

[0006] [Non-Patent Document 1] Organic Electronics 14 (2013)2721-2726 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] Despite being pointed out as having such problems, it is hard to say that the relationship between the chemical structure and properties of delayed fluorescence materials has been fully elucidated. For this reason, it is currently difficult to generalize the chemical structure of compounds useful as luminescent materials, and there are many unclear points.

[0008] Under such circumstances, the present inventors have conducted extensive research with the aim of providing a more useful compound as a light-emitting material for light-emitting elements. Then, they have intensively studied to derive and generalize the general formula of a more useful compound as a light-emitting material.

Means for Solving the Problems

[0009] As a result of intensive studies to achieve the above object, the present inventors have found that among benzonitrile derivatives, a compound having a structure satisfying specific conditions is useful as a light-emitting material. The present invention has been proposed based on such findings, and specifically, has the following configurations.

[0010] [1] A compound represented by the following general formula (1).

Chemical Formula

[10] R 1 ~R 5 Two of which are each independently a substituted or unsubstituted aromatic hydrocarbon ring group, the compound according to any one of [1] to [9].

[11] R 1 ~R 5 Two of which are each independently a substituted or unsubstituted aromatic heterocyclic group containing a nitrogen atom as a ring skeleton constituent atom, the compound according to any one of [1] to

[10] .

[12] R 1 ~R 5 The two of which are identical to each other, the compound according to

[10] or

[11] .

[13] A light-emitting material comprising the compound according to any one of [1] to

[12] .

[14] A light-emitting device comprising the compound according to any one of [1] to

[12] .

[15] The light-emitting device according to

[14] , wherein the light-emitting device has a light-emitting layer, and the light-emitting layer contains the compound and a host material.

[16] The light-emitting device according to

[14] , wherein the light-emitting device has a light-emitting layer, the light-emitting layer contains the compound and a light-emitting material, and emits light mainly from the light-emitting material. [Advantages of the Invention]

[0011] The compound of the present invention is useful as a light-emitting material. Further, among the compounds of the present invention, there are compounds that emit delayed fluorescence. Further, the compound of the present invention is also useful as a material for an organic light-emitting device. [Brief Description of the Drawings]

[0012]

Figure 1

[0013] Hereinafter, the content of the present invention will be described in detail. The description of the constituent elements described below may be based on typical embodiments or specific examples of the present invention, but the present invention is not limited to such embodiments or specific examples. In the present specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. Further, the isotope species of the hydrogen atoms present in the molecule of the compound used in the present invention are not particularly limited. For example, all the hydrogen atoms in the molecule may be 1 H, or some or all of them may be 2 H (deuterium D).

[0014] [Compound Represented by General Formula (1)] [Chemical Formula]

[0015] R in the general formula (1) 1 ~R 5 Two of them each independently represent a substituted or unsubstituted aromatic hydrocarbon ring group or a substituted or unsubstituted aromatic heterocyclic group containing a nitrogen atom as a ring skeleton constituent atom.

[0016] The "aromatic hydrocarbon ring group" referred to in the present invention means a group in which the bonding ring (one ring) is an aromatic hydrocarbon ring. For example, it includes a phenyl group bonded to one carbon atom constituting the ring skeleton of a benzene ring. The hydrogen atoms constituting the aromatic hydrocarbon ring to which it binds may be substituted. Further, one or more rings may be condensed to the aromatic hydrocarbon ring to which it binds. Further, another ring may be condensed to the condensed ring. Examples of the condensed ring include an aromatic hydrocarbon ring, an aromatic heterocyclic ring, an aliphatic hydrocarbon ring, and an aliphatic heterocyclic ring. Examples of the aromatic hydrocarbon ring include a benzene ring. Examples of the aromatic heterocyclic ring include a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a pyrazole ring, and an imidazole ring. Examples of the aliphatic hydrocarbon ring include a cyclopentane ring, a cyclohexane ring, and a cycloheptane ring. Examples of the aliphatic heterocyclic ring include a piperidine ring, a pyrrolidine ring, and an imidazoline ring. Specific examples of the condensed ring constituting the aromatic hydrocarbon ring include a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyran ring, and a tetracene ring. Further, specific examples of the condensed ring containing a hetero atom include an indole ring, an isoindole ring, a benzimidazole ring, a benzotriazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, and a cinnoline ring. However, in these specific examples of the condensed ring, they are bonded to the carbon atoms constituting the benzene ring. R 1 ~R 5 The number of carbon atoms of the substituted or unsubstituted aromatic hydrocarbon ring group that R~R can take is preferably 6 to 40, more preferably 6 to 30, and even more preferably 6 to 20. The number of ring skeleton constituent atoms of the bonding ring is preferably 6 to 14, more preferably 6 to 12, and even more preferably 6.

[0017] As used in the present invention, the "aromatic heterocyclic group" means a group in which the ring (one ring) to which it is attached is an aromatic heterocyclic ring and is bonded through one carbon atom constituting the ring skeleton of the aromatic heterocyclic ring. For example, it includes a pyridyl group bonded through one carbon atom constituting the ring skeleton of a pyridine ring. R 1 ~R 5 The aromatic heterocyclic ring that R R 1 ~R 5 ~R may adopt contains a nitrogen atom as a ring skeleton-constituting atom of the ring (one ring) to which it is attached. The ring to which it is attached may contain a hetero atom other than the nitrogen atom as a ring skeleton-constituting atom, but preferably contains only a nitrogen atom as the ring skeleton-constituting hetero atom. The number of hetero atoms contained in the ring to which it is attached is preferably 1 to 3, more preferably 1 or 2. Examples of the ring to which it is attached include a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a pyrazole ring, and an imidazole ring. The hydrogen atoms constituting the ring to which it is attached may be substituted. Also, one or more rings may be condensed. Further, another ring may be condensed to the condensed ring. Examples of the ring to be condensed include an aromatic hydrocarbon ring, an aromatic heterocyclic ring, an aliphatic hydrocarbon ring, and an aliphatic heterocyclic ring. For specific examples of the aromatic hydrocarbon ring, aromatic heterocyclic ring, aliphatic hydrocarbon ring, and aliphatic heterocyclic ring mentioned here, reference can be made to the corresponding descriptions in the above description of the "aromatic hydrocarbon ring group". Specific examples of the condensed ring constituting the aromatic heterocyclic ring include a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, a cinnoline ring, and a pteridine ring. However, in these specific examples of the condensed ring, they are bonded through a carbon atom constituting the ring skeleton of the heterocyclic ring.

[0018] R 1 ~R5 The aromatic hydrocarbon ring group and the aromatic heterocyclic group that can be adopted may be substituted. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, a heteroaryloxy group, a heteroarylthio group, and a cyano group. These substituents may be further substituted with another substituent. Examples of the preferred group of substituents include an alkyl group, an aryl group, an alkoxy group, and an alkylthio group. The "alkyl group" referred to here may be linear, branched, or cyclic. Also, two or more of the linear portion, the cyclic portion, and the branched portion may be mixed. The number of carbon atoms of the alkyl group can be, for example, 1 or more, 2 or more, 4 or more. Also, the number of carbon atoms can be 30 or less, 20 or less, 10 or less, 6 or less, 4 or less. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, an n-hexyl group, an isohexyl group, a 2-ethylhexyl group, an n-heptyl group, an isoheptyl group, an n-octyl group, an isooctyl group, an n-nonyl group, an isononyl group, an n-decanyl group, an isodecanyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The alkyl group as a substituent may be further substituted with an aryl group. The "alkenyl group" may be linear, branched, or cyclic. Also, two or more of the linear portion, the cyclic portion, and the branched portion may be mixed. The number of carbon atoms of the alkenyl group can be, for example, 2 or more, 4 or more. Also, the number of carbon atoms can be 30 or less, 20 or less, 10 or less, 6 or less, 4 or less. Specific examples of the alkenyl group include an ethenyl group, an n-propenyl group, an isopropenyl group, an n-butenyl group, an isobutenyl group, an n-pentenyl group, an isopentenyl group, an n-hexenyl group, an isohexenyl group, and a 2-ethylhexenyl group. The alkenyl group as a substituent may be further substituted with a substituent. ​The "aryl group" and "heteroaryl group" may be monocyclic or a condensed ring in which two or more rings are fused. When it is a condensed ring, the number of fused rings is preferably 2 to 6, and can be selected, for example, from 2 to 4. Specific examples of the ring include benzene ring, pyridine ring, pyrimidine ring, triazine ring, naphthalene ring, anthracene ring, phenanthrene ring, triphenylene ring, quinoline ring, pyrazine ring, quinoxaline ring, naphthyridine ring. Specific examples of the arylene group or heteroarylene group include phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthracenyl group, 2-anthracenyl group, 9-anthracenyl group, 2-pyridyl group, 3-pyridyl group, 4-pyridyl group. For the alkyl moieties of the "alkoxy group" and "alkylthio group", the descriptions and specific examples of the above alkyl groups can be referred to. For the aryl moieties of the "aryloxy group" and "arylthio group", the descriptions and specific examples of the above aryl groups can be referred to. For the heteroaryl moieties of the "heteroaryloxy group" and "heteroarylthio group", the descriptions and specific examples of the above heteroaryl groups can be referred to.

[0019] R in general formula (1) 1 ~R 5 Among them, any two of the substituted or unsubstituted aromatic hydrocarbon ring groups or substituted or unsubstituted aromatic heterocyclic groups containing a nitrogen atom as a ring skeleton constituent atom may be used. The two may be the same or different from each other, but are preferably the same. As combinations of the two, for example, combinations of R 3 and R 5 , R 2 and R 5 , R 1 and R 5 , R 2 and R 4 can be given as preferred examples. As more preferred examples, combinations of R 3 and R 5 , R 2 and R 5 can be given. In a preferred embodiment of the present invention, R in the general formula (1) 1 ~R 5 Among them, two are each independently a substituted or unsubstituted aromatic hydrocarbon group. More preferably, R 3 And R 5 , R 2 And R 5 , R 1 And R 5 , Or R 2 And R 4 Are each independently a substituted or unsubstituted aromatic hydrocarbon group. For example, R 3 And R 5 Are each independently a substituted or unsubstituted aromatic hydrocarbon group, and a group in which R 2 And R 5 Are each independently a substituted or unsubstituted aromatic hydrocarbon group can be mentioned.

[0020] Hereinafter, specific examples of a substituted or unsubstituted aromatic hydrocarbon group and a substituted or unsubstituted aromatic heterocyclic group containing a nitrogen atom as a ring skeleton constituent atom, which can be taken by two of R 1 ~R 5 In the general formula (1), are shown.

Chemical formula

[0021] Among R 1 ~R 5 In the general formula (1), three are each independently a donor group. However, the donor group here is not a substituted or unsubstituted aromatic hydrocarbon group, nor a substituted or unsubstituted aromatic heterocyclic group containing a nitrogen atom as a ring skeleton constituent atom. The "donor group" in the present invention is a group having a negative Hammett σp value. Here, the "Hammett σp value" was proposed by L.P. Hammett and quantifies the influence of a substituent on the reaction rate or equilibrium of a para-substituted benzene derivative. Specifically, the following formula established between the substituent and the reaction rate constant or equilibrium constant in a para-substituted benzene derivative: log(k / k0) = ρσp or log(K / K0) = ρσp where σp is a constant specific to the substituent in . In the above formula, k is the rate constant of a benzene derivative without a substituent, k0 is the rate constant of a benzene derivative substituted with a substituent, K is the equilibrium constant of a benzene derivative without a substituent, K0 is the equilibrium constant of a benzene derivative substituted with a substituent, and ρ represents a reaction constant determined by the type and conditions of the reaction. For the description of the "Hammett σp value" in the present invention and the numerical values of each substituent, reference can be made to the description of the σp value in Hansch, C. et al., Chem. Rev., 91, 165 - 195 (1991). A group with a negative Hammett σp value tends to exhibit electron-donating (donor) properties, and a group with a positive Hammett σp value tends to exhibit electron-withdrawing (acceptor) properties.

[0022] The donor group in the present invention is preferably a group containing a substituted amino group. The substituent bonded to the nitrogen atom of the amino group is preferably a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group, more preferably a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group. The substituted amino group is particularly preferably a substituted or unsubstituted diarylamino group or a substituted or unsubstituted diheteroarylamino group. The donor group in the present invention may be a group bonded through the nitrogen atom of the substituted amino group, or a group bonded through a group to which the substituted amino group is bonded. The group to which the substituted amino group is bonded is preferably a π-conjugated group. More preferably, it is a group bonded through the nitrogen atom of the substituted amino group. For the alkyl group, alkenyl group, aryl group, and heteroaryl group as substituents mentioned here, reference can be made to the corresponding descriptions of the substituents of the aromatic hydrocarbon ring group and the aromatic heterocyclic ring group above. Particularly preferred as the donor group in the present invention is a substituted or unsubstituted carbazol-9-yl group. Each of the three donor groups present in the general formula (1) is preferably an independently substituted or unsubstituted carbazol-9-yl group. Examples of the substituent of the carbazol-9-yl group include an alkyl group, an alkenyl group, an aryl group, a heteroaryl group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, a heteroaryloxy group, a heteroarylthio group, and a substituted amino group. Preferred substituents include an alkyl group, an aryl group, and a substituted amino group. For the description of the substituted amino group, reference can be made to the description in the previous paragraph. Further, the substituted amino group herein includes a substituted or unsubstituted carbazolyl group, particularly a substituted or unsubstituted carbazol-9-yl group. The donor group in the present invention preferably has 5 or more atoms other than hydrogen atoms, more preferably 10 or more atoms, and even more preferably 13 or more atoms. Further, it is preferably 80 or less, more preferably 60 or less, and even more preferably 40 or less.

[0023] At least one of the three donor groups present in general formula (1) is a carbazolyl-9-yl group condensed with a benzofuran ring. The benzofuran ring may be condensed with the carbazolyl-9-yl group via a furan ring, or may be condensed with the carbazolyl-9-yl group via a benzene ring. The former is preferred. Also, the carbazolyl-9-yl group may have only one benzofuran ring condensed thereto, or two or more benzofuran rings may be condensed thereto. When two or more benzofuran rings are condensed, they may have the same structure or different structures. Also, the types of the condensed rings may be the same or different. The carbazolyl-9-yl group condensed with a benzofuran ring may be substituted. As the substituent, the substituents listed as the substituents of the carbazol-9-yl group can be preferably referred to. When a ring other than the benzofuran ring is condensed with the carbazolyl-9-yl group as the carbazolyl-9-yl group condensed with a benzofuran ring, it is preferable that the condensed ring is only a ring selected from the group consisting of an aromatic hydrocarbon ring and an aliphatic hydrocarbon ring, and more preferably only an aromatic hydrocarbon ring. It is also preferable that the carbazolyl-9-yl group condensed with a benzofuran ring has no ring other than the benzofuran ring condensed with the carbazolyl-9-yl group. Further, it is also preferable that the carbazolyl-9-yl group condensed with a benzofuran ring is unsubstituted.

[0024] The three donor groups present in general formula (1) are not all the same. All three may be different from each other, or two may be the same and one may be different. The latter is preferred. As a preferred embodiment of the present invention, there can be mentioned a case where two are carbazolyl-9-yl groups condensed with a benzofuran ring and the remaining one is another donor group. As another preferred embodiment of the present invention, there can be mentioned a case where one is a carbazolyl-9-yl group condensed with a benzofuran ring and the other two are other donor groups. The other donor group is preferably a carbazolyl-9-yl group having no condensed benzofuran ring.

[0025] R in the general formula (1) 1 ~R 5 Any three of them that are donor groups may be in any combination. Preferred combinations include R 1 and R 2 and R 4 and examples of modes where R 1 and R 2 are the same and R 4 is different can be given. Also, examples of modes where R 1 and R 4 are the same and R 2 is different can also be given. Furthermore, examples of modes where R 2 and R 4 are the same and R 1 is different can also be given. Another preferred combination includes R 1 and R 3 and R 4 and examples of modes where R 1 and R 3 are the same and R 4 is different can be given. Also, examples of modes where R 1 and R 4 are the same and R 3 is different can also be given. Furthermore, examples of modes where R 3 and R 4 are the same and R 1 is different can also be given. Another preferred combination includes R 2 and R 3 and R 4 and examples of modes where R 2 and R 3 are the same and R 4 is different can be given. Also, examples of modes where R 2 and R 4 are the same and R 3 is different can also be given. Furthermore, examples of modes where R 3 and R 4 are the same and R 2 is different can also be given. Another preferred combination includes R 1 and R 3 and R 5 and examples of modes where R 1 and R 3 are the same and R 5can illustrate different modes. Also, R 1 and R 5 being the same and R 3 being different can also illustrate a mode. Furthermore, R 3 and R 5 being the same and R 1 being different can also illustrate a mode.

[0026] In the following, specific examples of donor groups that three of R 1 to R 5 in the general formula (1) can adopt are shown. D21 to D26 correspond to specific examples of a carbazolyl-9-yl group condensed with a benzofuran ring.

Chemical formula

Chemical formula

Chemical formula

[0027] In a preferred embodiment of the present invention, the compound represented by the general formula (1) is composed of only atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms. In a preferred embodiment of the present invention, the compound represented by the general formula (1) is composed of only carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms.

[0028] In Tables 1 and 2 below, specific examples of the compound represented by the general formula (1) are shown. In Tables 1 and 2, the structure of the compound is shown by specifying R 1 to R 5 for each compound. In Table 2, a plurality of compounds are grouped and displayed for each row. For example, for Compounds 4537 to 4572 in Table 2, R 2 to R 5 are fixed to D1, Ar1, D1, and Ar1, respectively. And those in which R 1 is D27 to D62 are sequentially Compounds 4537 to 4572. For Compounds 4573 to 5868, R 1is D1, R 3 and R 5 is Ar1, in the structure where R 2 is D27, and R 4 is D27 to D62 are sequentially designated as Compounds 4573 to 4608, and R 2 is D28, and R 4 is D27 to D62 are sequentially designated as Compounds 4609 to 4644, and R 3 is D29, and R 4 is D27 to D62 are sequentially designated as Compounds 4645 to 4680, and the compound numbers are assigned in this manner. Finally, R 2 is D62, and R 4 is D27 to D62 are sequentially designated as Compounds 5833 to 5868. In Tables 1 and 2, Compounds 1 to 16452 have their structures individually specified and are specifically disclosed in this specification. Also, those in which all the hydrogen atoms present in the molecules of Compounds 1 to 16452 are replaced with deuterium atoms are disclosed as Compounds 1d to 16452d. In addition, when there are rotational isomers among the following compounds, the mixture of rotational isomers and each separated rotational isomer are also considered to be disclosed in this specification. Further, in Tables 1 to 6 below, Ar82 represents the same structure as Ar1d (the structure in which all hydrogen atoms of Ar1 are replaced with deuterium atoms).

Table 1-1

Table 1-2

Table 1-3

Table 1-4

Table 1-5

Table 1-6

Table 1-7

Table 1-8

Table 1-9

Table 1-10

Table 1-11

Table 1-12

Table 1-13

Table 1-14

Table 1-15

Table 1-16

Table 1-17

Table 1-18

Table 1-19

Table 1-20

Table 1-21

Table 1-22

Table 1-23

Table 1-24

Table 1-25

Table 1-26

Table 1-27

Table 1-28

Table 1-29

Table 1-30

Table 1-31

Table 2

[0029] When the compound represented by the general formula (1) is intended to be used by forming a film of an organic layer containing the compound represented by the general formula (1) by a vapor deposition method, for example, the molecular weight is preferably 1500 or less, more preferably 1200 or less, still more preferably 1000 or less, and even more preferably 900 or less. The lower limit of the molecular weight is the molecular weight of the smallest compound represented by the general formula (1). The compound represented by the general formula (1) may be formed into a film by a coating method regardless of its molecular weight. If a coating method is used, it is possible to form a film even with a compound having a relatively large molecular weight. The compound represented by the general formula (1) has the advantage of being easily dissolved in an organic solvent among cyanobenzene-based compounds. Therefore, the compound represented by the general formula (1) is easy to apply the coating method and is easy to purify and increase the purity.

[0030] Applying the present invention, it is also conceivable to use a compound containing a plurality of structures represented by the general formula (1) in the molecule as a light-emitting material. For example, it is conceivable to use, as a light-emitting material, a polymer obtained by previously allowing a polymerizable group to be present in the structure represented by the general formula (1) and polymerizing the polymerizable group. Specifically, a monomer containing a polymerizable functional group in any one of R 1 ~R 5 is prepared, and this is polymerized alone or copolymerized with other monomers to obtain a polymer having a repeating unit, and it is conceivable to use the polymer as a light-emitting material. Alternatively, it is also conceivable to obtain dimers or trimers by coupling compounds having the structure represented by the general formula (1) and use them as light-emitting materials.

[0031] Examples of the polymer having a repeating unit containing the structure represented by the general formula (1) include polymers containing the structure represented by the following general formula (3) or (4).

Chemical formula

[0032] In the general formula (3) or (4), Q represents a group containing the structure represented by the general formula (1), and L 1 and L 2 represent a linking group. The number of carbon atoms of the linking group is preferably 0 to 20, more preferably 1 to 15, and still more preferably 2 to 10. The linking group preferably has a structure represented by -X 11 -L 11 -. Here, X 11 represents an oxygen atom or a sulfur atom, and is preferably an oxygen atom. L 11 represents a linking group, and is preferably a substituted or unsubstituted alkylene group or a substituted or unsubstituted arylene group, and more preferably a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms or a substituted or unsubstituted phenylene group. In the general formula (3) or (4), R 101 , R 102 , R 103 and R 104Each independently represents a substituent. Preferably, it is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 6 carbon atoms, or a halogen atom. More preferably, it is an unsubstituted alkyl group having 1 to 3 carbon atoms, an unsubstituted alkoxy group having 1 to 3 carbon atoms, a fluorine atom, or a chlorine atom. Even more preferably, it is an unsubstituted alkyl group having 1 to 3 carbon atoms or an unsubstituted alkoxy group having 1 to 3 carbon atoms. L 1 and L 2 The linking group represented by is bonded to any one of R 1 ~R 5 in the general formula (1) constituting Q. Two or more linking groups may be linked to one Q to form a crosslinked structure or a network structure.

[0033] As specific structural examples of the repeating unit, the structures represented by the following formulas (5) to (8) can be cited.

Chemical formula

[0034] Polymers having repeating units including these formulas (5) to (8) have a hydroxy group introduced into any one of R 1 ~R 5 in the general formula (1), and can be synthesized by reacting the following compound using it as a linker to introduce a polymerizable group and polymerizing the polymerizable group.

Chemical formula

[0035] A polymer containing a structure represented by the general formula (1) in the molecule may be a polymer composed only of repeating units having the structure represented by the general formula (1), or may be a polymer containing repeating units having other structures. Further, the repeating units having the structure represented by the general formula (1) contained in the polymer may be of a single type or two or more types. Examples of the repeating units having no structure represented by the general formula (1) include those derived from monomers used in ordinary copolymerization. For example, repeating units derived from monomers having an ethylenically unsaturated bond such as ethylene and styrene can be mentioned.

[0036] [Synthesis method of the compound represented by the general formula (1)] The compound represented by the general formula (1) is a novel compound. The compound represented by the general formula (1) can be synthesized by combining known reactions. For example, using cyanobenzene trifluoride as a starting material and reacting it with a halide of an aromatic hydrocarbon in the presence of a catalyst, a derivative in which two aromatic hydrocarbon ring groups are introduced in place of hydrogen atoms can be obtained. By reacting the obtained derivative with carbazole in the presence of a catalyst, a part of the fluorine atoms is substituted with a carbazol-9-yl group, and further, by reacting with carbazole condensed with a benzofuran ring, the remaining fluorine atoms can be substituted with a carbazol-9-yl group condensed with a benzofuran ring. Thereby, the target compound represented by the general formula (1) can be synthesized. For the specific conditions and reaction procedures of this reaction, reference can be made to the synthesis examples described later. Also, other compounds represented by the general formula (1) can be synthesized by using similar procedures and known synthesis methods.

[0037] [Organic light-emitting device] The compound represented by the general formula (1) of the present invention is useful as a light-emitting material for an organic light-emitting device. Therefore, the compound represented by the general formula (1) of the present invention can be effectively used as a light-emitting material in the light-emitting layer of an organic light-emitting device. Further, the compound represented by the general formula (1) of the present invention may be used as a host or an assist dopant. Among the compounds represented by the general formula (1), there are delayed phosphors that emit delayed fluorescence. That is, the present invention also provides an invention of a delayed phosphor having a structure represented by the general formula (1), an invention of using the compound represented by the general formula (1) as a delayed phosphor, and an invention of a method for emitting delayed fluorescence using the compound represented by the general formula (1). An organic light-emitting device using such a compound as a light-emitting material emits delayed fluorescence and has a feature of high luminous efficiency. The principle will be described as follows by taking an organic electroluminescence device as an example.

[0038] In an organic electroluminescence device, carriers are injected from both the positive and negative electrodes into a light-emitting material to generate an excited state of the light-emitting material and cause it to emit light. Usually, in the case of a carrier-injecting type organic electroluminescence device, among the generated excitons, 25% are excited to the singlet excited state, and the remaining 75% are excited to the triplet excited state. Therefore, it is more energy-efficient to utilize phosphorescence, which is light emission from the triplet excited state. However, since the triplet excited state has a long lifetime, saturation of the excited state and energy deactivation due to interaction with excitons in the triplet excited state occur, and generally the quantum yield of phosphorescence is not high. On the other hand, a delayed fluorescence material emits fluorescence by reverse intersystem crossing to the singlet excited state after energy transitions to the triplet excited state due to intersystem crossing or the like, followed by triplet-triplet annihilation or absorption of thermal energy. In an organic electroluminescence device, a thermally activated delayed fluorescence material that utilizes absorption of thermal energy is considered to be particularly useful. When a delayed fluorescence material is used in an organic electroluminescence device, excitons in the singlet excited state emit fluorescence as usual. On the other hand, excitons in the triplet excited state absorb heat emitted by the device and undergo intersystem crossing to the singlet excited state to emit fluorescence. At this time, since it is light emission from the singlet excited state, it emits light at the same wavelength as fluorescence, but due to the reverse intersystem crossing from the triplet excited state to the singlet excited state, the lifetime of the generated light (emission lifetime) is longer than that of normal fluorescence, and thus it is observed as fluorescence that is more delayed than these. This can be defined as delayed fluorescence. By using such a thermally activated reverse intersystem crossing mechanism, it is possible to increase the ratio of the compound in the singlet excited state, which is usually generated only 25%, to 25% or more by absorbing thermal energy after carrier injection. If a compound that emits strong fluorescence and delayed fluorescence even at a low temperature of less than 100 °C is used, intersystem crossing from the triplet excited state to the singlet excited state occurs sufficiently due to the heat of the device to emit delayed fluorescence, so that the luminous efficiency can be dramatically improved.

[0039] By using the compound represented by the general formula (1) of the present invention as a light-emitting material for the light-emitting layer, excellent organic light-emitting devices such as organic photoluminescence devices (organic PL devices) and organic electroluminescence devices (organic EL devices) can be provided. The organic photoluminescence device has a structure in which at least a light-emitting layer is formed on a substrate. Further, the organic electroluminescence device has a structure in which at least an anode, a cathode, and an organic layer are formed between the anode and the cathode. The organic layer includes at least a light-emitting layer, and may consist only of the light-emitting layer, or may have one or more organic layers in addition to the light-emitting layer. Examples of such other organic layers include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an exciton blocking layer. The hole transport layer may be a hole injection transport layer having a hole injection function, and the electron transport layer may be an electron injection transport layer having an electron injection function. A structural example of a specific organic electroluminescence device is shown in FIG. 1. In FIG. 1, 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents a light-emitting layer, 6 represents an electron transport layer, and 7 represents a cathode. Hereinafter, each member and each layer of the organic electroluminescence device will be described. Note that the description of the substrate and the light-emitting layer also applies to the substrate and the light-emitting layer of the organic photoluminescence device.

[0040] (Substrate) The organic electroluminescence device of the present invention is preferably supported on a substrate. There is no particular limitation on this substrate, and any substrate that has been conventionally used in organic electroluminescence devices may be used. For example, a substrate made of glass, transparent plastic, quartz, silicon, or the like can be used.

[0041] (Anode) As the anode in an organic electroluminescence device, those using a metal, alloy, electrically conductive compound, or a mixture thereof having a large work function (4 eV or more) as the electrode material are preferably used. Specific examples of such electrode materials include metals such as Au, CuI, indium tin oxide (ITO), SnO2, ZnO and other conductive transparent materials. Also, materials such as IDIXO (In2O3-ZnO) that can form an amorphous and transparent conductive film may be used. The anode may form a thin film of these electrode materials by methods such as evaporation or sputtering, and form a pattern of a desired shape by photolithography. Alternatively, when pattern accuracy is not required much (about 100 μm or more), a pattern may be formed through a mask of a desired shape during evaporation or sputtering of the above electrode materials. Or, when a material that can be applied such as an organic conductive compound is used, wet film formation methods such as printing or coating methods can also be used. When extracting light emission from this anode, it is desirable to make the transmittance greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / sq. (ohms per square) or less. Furthermore, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

[0042] (Cathode) On one hand, as the cathode, those using a metal with a small work function (4 eV or less) (referred to as an electron-injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as the electrode material are used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2O3) mixture, indium, lithium / aluminum mixture, rare earth metals, and the like. Among these, from the viewpoints of electron injection property and durability against oxidation and the like, a mixture of an electron-injecting metal and a second metal which is a metal having a larger work function value and being more stable than this, for example, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2O3) mixture, lithium / aluminum mixture, aluminum, etc. are preferable. The cathode can be fabricated by forming a thin film of these electrode materials by methods such as vapor deposition or sputtering. Further, the sheet resistance as the cathode is preferably several hundred Ω / sq. (ohms per square) or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In addition, in order to transmit the emitted light, it is advantageous for improving the emission luminance if either the anode or the cathode of the organic electroluminescence element is transparent or translucent. Also, by using the conductive transparent material described in the explanation of the anode as the cathode, a transparent or translucent cathode can be fabricated, and by applying this, an element in which both the anode and the cathode have permeability can be fabricated.

[0043] (Light-emitting layer) The light-emitting layer is a layer that emits light after excitons are generated by the recombination of holes and electrons injected from the anode and cathode, respectively. Although the light-emitting material alone may be used as the light-emitting layer, it preferably contains a light-emitting material and a host material. As the light-emitting material, one or more selected from the group of compounds of the present invention represented by the general formula (1) can be used. In order for the organic electroluminescence device and the organic photoluminescence device of the present invention to exhibit high luminous efficiency, it is important to confine singlet excitons and triplet excitons generated in the light-emitting material within the light-emitting material. Therefore, it is preferable to use a host material in addition to the light-emitting material in the light-emitting layer. As the host material, an organic compound having at least one of singlet excitation energy and triplet excitation energy higher than that of the light-emitting material of the present invention can be used. As a result, singlet excitons and triplet excitons generated in the light-emitting material of the present invention can be confined within the molecules of the light-emitting material of the present invention, and its luminous efficiency can be fully extracted. However, even if singlet excitons and triplet excitons cannot be sufficiently confined, it may be possible to obtain high luminous efficiency. Therefore, any host material capable of realizing high luminous efficiency can be used in the present invention without particular limitation. In the organic light-emitting device or the organic electroluminescence device of the present invention, light emission occurs from the light-emitting material of the present invention contained in the light-emitting layer. This light emission includes both fluorescence emission and delayed fluorescence emission. However, a part or partially, light emission from the host material may be present. The content of the compound represented by the general formula (1) in the light-emitting layer is preferably less than 50% by weight. Further, the upper limit value of the content of the compound represented by the general formula (1) is preferably less than 30% by weight, and the upper limit value of the content can also be, for example, less than 20% by weight, less than 10% by weight, less than 5% by weight, less than 3% by weight, less than 1% by weight, less than 0.5% by weight. The lower limit value is preferably 0.001% by weight or more, and can also be, for example, more than 0.01% by weight, more than 0.1% by weight, more than 0.5% by weight, more than 1% by weight. As the host material in the light-emitting layer, an organic compound having a hole-transporting ability, an electron-transporting ability, preventing the emission wavelength from shifting to a longer wavelength, and having a high glass transition temperature is preferable. The compound represented by the general formula (1) can also be used as the host material of the light-emitting layer.

[0044] (Injection layer) The injection layer is a layer provided between the electrode and the organic layer to reduce the driving voltage and improve the emission luminance. There are a hole injection layer and an electron injection layer, which may be present between the anode and the light-emitting layer or the hole-transporting layer, and between the cathode and the light-emitting layer or the electron-transporting layer. The injection layer can be provided as needed.

[0045] (Blocking layer) The blocking layer is a layer that can block the diffusion of charges (electrons or holes) and / or excitons present in the light-emitting layer outside the light-emitting layer. The electron blocking layer can be disposed between the light-emitting layer and the hole-transporting layer to prevent electrons from passing through the light-emitting layer toward the hole-transporting layer. Similarly, the hole blocking layer can be disposed between the light-emitting layer and the electron-transporting layer to prevent holes from passing through the light-emitting layer toward the electron-transporting layer. The blocking layer can also be used to prevent excitons from diffusing outside the light-emitting layer. That is, the electron blocking layer and the hole blocking layer can each also have the function of an exciton blocking layer. The electron blocking layer or exciton blocking layer referred to in this specification is used in the sense of including a layer having the functions of an electron blocking layer and an exciton blocking layer in one layer.

[0046] (Hole blocking layer) The hole blocking layer has the function of an electron-transporting layer in a broad sense. The hole blocking layer has the role of transporting electrons while preventing holes from reaching the electron-transporting layer, thereby improving the recombination probability of electrons and holes in the light-emitting layer. As the material of the hole blocking layer, the material of the electron-transporting layer described later can be used as needed.

[0047] (Electron blocking layer) An electron blocking layer has the function of transporting holes in a broad sense. The electron blocking layer plays a role in transporting holes while preventing electrons from reaching the hole transport layer, thereby improving the probability of recombination of electrons and holes in the light-emitting layer.

[0048] (Exciton blocking layer) An exciton blocking layer is a layer for preventing excitons generated by the recombination of holes and electrons in the light-emitting layer from diffusing into the charge transport layer. By inserting this layer, excitons can be efficiently confined within the light-emitting layer, and the light-emitting efficiency of the device can be improved. The exciton blocking layer can be inserted on either the anode side or the cathode side adjacent to the light-emitting layer, or both can be inserted simultaneously. That is, when the exciton blocking layer is on the anode side, it can be inserted adjacent to the light-emitting layer between the hole transport layer and the light-emitting layer. When inserted on the cathode side, it can be inserted adjacent to the light-emitting layer between the light-emitting layer and the cathode. Also, between the anode and the exciton blocking layer adjacent to the anode side of the light-emitting layer, a hole injection layer, an electron blocking layer, etc. can be provided. Between the cathode and the exciton blocking layer adjacent to the cathode side of the light-emitting layer, an electron injection layer, an electron transport layer, a hole blocking layer, etc. can be provided. When arranging the blocking layer, at least one of the singlet excitation energy and the triplet excitation energy of the material used as the blocking layer is preferably higher than the singlet excitation energy and the triplet excitation energy of the light-emitting material.

[0049] (Hole transport layer) The hole transport layer is composed of a hole transport material having the function of transporting holes, and the hole transport layer can be provided as a single layer or multiple layers. As a hole transport material, it has either the function of hole injection or transport or the function of electron blocking, and it may be either an organic or an inorganic material. Known hole transport materials that can be used include, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, carbazole derivatives, indolocarbazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers, particularly thiophene oligomers, etc. However, it is preferable to use porphyrin compounds, aromatic tertiary amine compounds, and styrylamine compounds, and it is more preferable to use aromatic tertiary amine compounds.

[0050] (Electron transport layer) The electron transport layer is made of a material having the function of transporting electrons, and the electron transport layer can be provided as a single layer or multiple layers. As an electron transport material (which may also serve as a hole blocking material), it only needs to have the function of transmitting electrons injected from the cathode to the light-emitting layer. Examples of electron transport layers that can be used include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, etc. Furthermore, in the above oxadiazole derivatives, thiadiazole derivatives in which the oxygen atom of the oxadiazole ring is replaced by a sulfur atom, and quinoxaline derivatives having a quinoxaline ring known as an electron-withdrawing group can also be used as electron transport materials. Furthermore, polymer materials in which these materials are introduced into the polymer chain or these materials are used as the main chain of the polymer can also be used.

[0051] When manufacturing an organic electroluminescence device, the compound represented by the general formula (1) may be used not only in one organic layer (for example, the electron transport layer), but also in a plurality of organic layers. In this case, the compounds represented by the general formula (1) used in each organic layer may be the same as or different from each other. For example, in addition to the electron transport layer and the light-emitting layer, the compound represented by the general formula (1) may also be used in the above injection layer, blocking layer, hole blocking layer, electron blocking layer, exciton blocking layer, hole transport layer, etc. The film forming method of these layers is not particularly limited, and either a dry process or a wet process may be used for production.

[0052] Hereinafter, preferable materials that can be used in the organic electroluminescence device will be specifically exemplified. However, the materials that can be used in the present invention should not be construed as being limited by the following exemplified compounds. Further, even a compound exemplified as a material having a specific function can be diverted as a material having other functions.

[0053] First, preferable compounds that can also be used as the host material of the light-emitting layer will be listed.

Chemical formula

[0054]

Chemical formula

[0055]

Chemical formula

[0056]

Chemical formula

[0057]

Chemical formula

[0058] Next, preferred compound examples that can be used as a hole injection material are given.

[0059]

Chem.

[0060] Next, preferred compound examples that can be used as a hole transport material are given.

[0061]

Chem.

[0062] Next, preferred compound examples that can be used as an electron blocking material are given.

[0063]

Chem.

[0064] Next, preferred compound examples that can be used as a hole blocking material are given.

[0065]

Chem.

[0066] Next, preferred compound examples that can be used as an electron transport material are given.

[0067]

Chem.

[0068] Next, preferred compound examples that can be used as an electron injection material are given.

[0069]

Chem.

[0070] Examples of preferable compounds as additional materials are given. For example, it is conceivable to add them as a stabilizing material or the like.

[0071]

Chemical formula

[0072] The organic electroluminescence device fabricated by the above method emits light by applying an electric field between the anode and the cathode of the obtained device. At this time, if the light emission is due to the singlet excitation energy, light with a wavelength corresponding to that energy level is confirmed as fluorescence emission and delayed fluorescence emission. Also, if the light emission is due to the triplet excitation energy, the wavelength corresponding to that energy level is confirmed as phosphorescence. Since normal fluorescence has a shorter fluorescence lifetime than delayed fluorescence emission, the emission lifetime can be distinguished between fluorescence and delayed fluorescence.

[0073] On the other hand, regarding phosphorescence, in ordinary organic compounds such as the compounds of the present invention, the triplet excitation energy is unstable, the rate constant of thermal deactivation is large, and the rate constant of light emission is small, so it is immediately deactivated and hardly observable at room temperature. In order to measure the triplet excitation energy of ordinary organic compounds, it can be measured by observing light emission under cryogenic conditions.

[0074] The organic electroluminescence device of the present invention can be applied to any of a single device, a device having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an X-Y matrix. According to the present invention, by incorporating a compound represented by the general formula (1) into the light-emitting layer, an organic light-emitting device with greatly improved luminous efficiency can be obtained. Organic light-emitting devices such as the organic electroluminescence device of the present invention can be further applied to various uses. For example, it is possible to manufacture an organic electroluminescence display device using the organic electroluminescence device of the present invention. For details, reference can be made to "Organic EL Display" (Ohmsha, Ltd.) co-authored by Seishi Tokito, Chihaya Adachi, and Hideyuki Murata. In particular, the organic electroluminescence device of the present invention can also be applied to organic electroluminescence lighting and backlights with high demand.

Examples

[0075] The features of the present invention will be further specifically described below with reference to synthesis examples and examples. The materials, treatment contents, treatment procedures, etc. shown below can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. The evaluation of the light-emitting characteristics was performed using a source meter (manufactured by Keithley Instruments, Inc.: 2400 series), a semiconductor parameter analyzer (manufactured by Agilent Technologies, Inc.: E5273A), an optical power meter measuring device (manufactured by Newport Corporation: 1930C), an optical spectroscope (manufactured by Ocean Optics, Inc.: USB2000), a spectro-radiometer (manufactured by Topcon Corporation: SR-3), and a streak camera (type C4334 manufactured by Hamamatsu Photonics K.K.).

[0076] (Synthesis Example 1) Synthesis of Compound 26 (1-1) Synthesis of Intermediate 1

Chemical formula

[0077] A solution of 1.57 g (10.0 mmol) of 2,3,5-trifluorobenzonitrile, 4.15 g (30.0 mmol) of potassium carbonate, 0.25 g (0.03 mmol) of Pd(PPh3)2Cl2, and 0.25 g (0.09 mmol) of tricyclohexylphosphine in xylene (30 mL) was added with 0.29 g (2.00 mmol) of 2-ethylhexanoic acid and 6.28 g (40.0 mmol) of bromobenzene under a nitrogen stream, and stirred at 80 °C for 24 hours and at 100 °C for 24 hours. The reaction solution was returned to room temperature, saturated aqueous ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The solvent was distilled off, and the residue was purified by silica gel column chromatography (hexane:chloroform = 9:1 - 7:3) to obtain 2.20 g (7.13 mmol, yield 73%) of Intermediate 1 as a white solid. 1 1H NMR (500 MHz, CDCl3, δ): 7.60 - 7.45 (m, 10H) ASAP MS spectrum analysis: C 19 H 10 F3N: theoretical value 309.08, observed value 310.10

[0078] (1 - 2) Synthesis of Intermediate 2

Chemical formula

[0079] Under a nitrogen stream, dimethylformamide (40 mL) was added to 0.35 g (14.7 mmol) of sodium hydride and 1.26 g (4.90 mmol) of 12H-[3,2-a]-benzofluorocarbazole, and the mixture was stirred at room temperature for 1 hour. The reaction mixture was added to a solution of Intermediate 1 (2.17 g, 7.00 mmol) in dimethylformamide (20 mL) at 0 °C and stirred for 10 hours. Then, the temperature was raised to 10 °C and stirred for 6 hours. Water was added to the reaction solution to quench it, and the mixture was extracted with ethyl acetate. The organic layer was washed with water and saturated brine, dried over anhydrous magnesium sulfate, and the solvent was distilled off. The crude product was purified by silica gel column chromatography (hexane:toluene = 2:1) to obtain 0.93 g (1.70 mmol, yield 35%) of Intermediate 2 as a pale yellow solid. 11H NMR (500 MHz, CDCl3, δ): 8.23 (d, J = 8.7 H Z , 1H), 8.17 (d, J = 6.9 H Z , 1H), 7.65 (d, J = 8.7 Hz, 1H), 7.63 (d, J = 8.7 H Z , 1H), 7.57 - 7.38 (m, 13H), 7.25 - 7.14 (m, 1H), 7.10 (t, J = 7.8 H Z , 1H), 6.13 (d, J = 7.8 H Z , 1H) ASAP MS spectrum analysis: C 37 H 20 F2N2O theoretical value 546.15, observed value 547.65

[0080] (1 - 3) Synthesis of Compound 26

Chemical Structure

[0081] Under a nitrogen stream, 1.04 g (6.24 mmol) of carbazole and 1.08 g (7.80 mmol) of potassium carbonate were added to dimethylformamide (26 mL), and the mixture was stirred at room temperature for 2 hours. Then 1.42 g (2.60 mmol) of Intermediate 2 was added to the reaction mixture, and the mixture was stirred at 100 °C for 16 hours. The reaction solution was cooled to room temperature, water was added, and the precipitate was filtered off. The residue on the filter was washed with methanol and dried under vacuum. The residue was purified by silica gel column chromatography (hexane:toluene = 2:5) to obtain 1.71 g (2.03 mmol, 76% yield) of Compound 26 as a pale yellow solid. 1 1H NMR (500 MHz, CDCl3, δ): 7.87 (t, J = 8.7 H Z , 2H), 7.81 (d, J = 8.7 H Z , 1H), 7.72 - 7.65 (m, 2H), 7.58 - 7.50 (m, 3H), 7.47 - 7.42 (m, 2H), 7.35 (d, J =8.2 H Z, 2H), 7.33 - 7.31 (m, 2H), 7.27 - 7.08 (m, 7H), 7.06 - 6.87 (m, 7H), 6.69 (t, J = 7.6 H Z , 1H), 6.69 - 6.58 (br, 2H), 6.55 (d, J = 8.2 H Z , 1H), 6.46 (t, J = 7.6 H Z , 1H), 6.39 - 6.29 (br, 2H), 6.27 (t, J = 8.2 H Z , 1H) ASAP MS spectrum analysis: C 61 H 36 N4O theoretical value 840.29, observed value 841.51

[0082] (Synthesis Example 2) Synthesis of Compound 1626 (2 - 1) Synthesis of Intermediate 3 [Chemical formula]

[0083] Under a nitrogen stream, 3.0 g (19.1 mmol) of 2,4,5 - trifluorobenzonitrile, 8.99 g (57.3 mmol) of bromobenzene, 7.92 g (57.3 mmol) of potassium carbonate, 0.28 g (1.91 mmol) of 2 - ethylhexanoic acid, and 0.48 g (1.72 mmol) of tricyclohexylphosphine in xylene solution (10 mL) were added with 0.40 g (0.57 mmol) of dichlorobis(triphenylphosphine)palladium(II). The mixture was stirred at 100 °C overnight. After the reaction solution was returned to room temperature, water was added to quench it, and it was extracted with chloroform. The solvent was distilled off by an evaporator and purified by silica gel column chromatography (hexane:chloroform) to obtain 4.99 g (16.13 mmol, yield 84.5%) of white solid Intermediate 3. 1 H NMR (400 MHz, CDCl3, δ): 7.51 - 7.54 (m, 4H), 7.56 - 7.61 (m, 6H) ASAP MS spectrum analysis: C 19 H10 F3N: Theoretical value 309.1, Observed value 310.1

[0084] (2-2) Synthesis of Intermediate 4

Chemical formula

[0085] Under a nitrogen stream, 3.24 g (19.4 mmol) of 9H-carbazole, 2.68 g (19.4 mmol) of potassium carbonate, and 3.00 g (9.7 mmol) of Intermediate 3 dissolved in dimethylformamide (25 mL) and tetrahydrofuran solution (25 mL) were stirred at 70 °C overnight. After returning this mixture to room temperature, saturated ammonium chloride solution was added to quench it, and it was extracted with chloroform. The solvent was distilled off by an evaporator and purified by silica gel column chromatography (hexane:ethyl acetate = 1:9) to obtain 0.50 g (0.83 mmol, yield 8.5%) of Intermediate 4. 1 H NMR (400 MHz, CDCl3, δ): 6.46 (t, J = 8.4 H Z , 2H), 6.57 (d, J = 6.4 H Z , 4H), 7.17 (t, J = 6.8 H Z , 4H), 7.23 (t, J= 7.2 H Z , 4H), 7.36 (dd, J = 8.8 H Z , 4H), 7.54-7.57 (m, 2H), 7.74 (d, J = 6.8 H Z , 2H), 7.99-8.02 (m, 4H), ASAP MS spectrum analysis: C 43 H 26 FN3: Theoretical value 603.2, Observed value 604.2

[0086] (2-3) Synthesis of Compound 1626

Chemical formula

[0087] Under a nitrogen stream, a dimethylformamide solution (10 mL) containing 0.51 g (1.99 mmol) of 5H-benzo[f]fluoro[3,2-c]carbazole, 0.27 g (1.99 mmol) of potassium carbonate, and 0.80 g (1.33 mmol) of Intermediate 4 was stirred at 120 °C overnight. After returning this mixture to room temperature, a saturated ammonium chloride solution was added to quench it, and it was extracted with chloroform. The solvent was distilled off by an evaporator and purified by silica gel column chromatography (hexane:ethyl acetate = 1:9) to obtain 0.95 g (1.13 mmol, yield 85.0%) of Compound 1626. 1 H NMR (400 MHz, CDCl3, δ): 6.39 (t, J = 8.0 H Z , 2H), 6.52 (t, J = 8.0 H Z , 1H), 6.60 (d, J = 8.0 H Z , 2H), 6.81 - 6.89 (m, 3H), 6.91 - 6.98 (m, 4H), 7.01 - 7.16 (m, 6H), 7.23 - 7.47 (m, 12H), 7.54 (t, J = 6.8 H Z , 2H), 7.85 (d, J = 6.8 H Z , 1H), 7.99 - 8.05 (m, 3H) ASAP MS spectrum analysis: C 61 H 36 N4O: Theoretical value 840.3, Observed value 841.3

[0088] (Synthesis Example 3) Synthesis of Compound 3387 (3 - 1) Synthesis of Intermediate 5

Chemical Structure

[0089] To a solution of 3.00 g (19.1 mmol) of 3,4,5-trifluorobenzonitrile, 7.92 g (57.0 mmol) of potassium carbonate, 0.42 g (0.57 mmol) of Pd(PPh3)2Cl2, and 0.48 g (1.72 mmol) of tricyclohexylphosphine in xylene (57 mL), 0.55 g (3.82 mmol) of 2-ethylhexanoic acid and 12.0 g (76.4 mmol) of bromobenzene were added under a nitrogen stream, and the mixture was stirred at 80 °C for 7 hours and at 100 °C for 16 hours. The reaction solution was returned to room temperature, saturated aqueous ammonium chloride solution was added, and the mixture was extracted with ethyl acetate. The solvent was distilled off, and the residue was purified by silica gel column chromatography (hexane:dichloromethane = 1 / 1, hexane:ethyl acetate = 3 / 17) to obtain 4.34 g (14.0 mmol, yield 73%) of Intermediate 5 as a white solid. 1 1H NMR (500 MHz, CDCl3, δ): 7.53 - 7.43 (m, 10H) ASAP MS spectrum analysis: C 19 H 10 F3N: calculated value 309.08, observed value 310.04

[0090] (3 - 2) Synthesis of Intermediate 6

Chemical formula

[0091] Under a nitrogen stream, 1.00 g (3.88 mmol) of 7H - benzofuro[2,3 - b]carbazole, 1.50 g (4.85 mmol) of Intermediate 5, and 1.01 g (7.28 mmol) of potassium carbonate were added with dimethylformamide (15 mL), and the mixture was stirred at 100 °C for 13 hours. Water was added to the reaction solution to quench it, and the suspension was filtered. The crude product was purified by silica gel column chromatography (hexane:dichloromethane = 2:3) to obtain 2.07 g (3.79 mmol, yield 78%) of Intermediate 6. 11H NMR (500 MHz, CDCl3, δ): 8.64 (s, 1H), 8.23 (d, J = 7.5 Hz, 1H), 8.06 (d, J = 7.5 Hz, 1H), 7.64 - 7.35 (m, 16H), 7.25 - 7.24 (m, 1H) ASAP MS spectrum analysis: C 37 H 20 F2N2O theoretical value 546.15, observed value 547.24

[0092] (3 - 3) Synthesis of Compound 3387

Chemical Structure

[0093] Under a nitrogen stream, 1.10 g (6.58 mmol) of 9H - carbazole, 1.50 g (2.74 mmol) of Intermediate 6, and 1.33 g (9.59 mmol) of potassium carbonate were added with dimethylformamide (19 mL), and the mixture was stirred at 130 °C for 15 hours. Water was added to the reaction solution to quench it, and the suspension was filtered. The crude product was purified by silica gel column chromatography (o - dichlorobenzene), then dissolved in o - dichlorobenzene and precipitated with methanol, and the solid was filtered and purified to obtain 2.05 g (2.44 mmol, yield 89%) of Compound 3387. 1 1H NMR (400 MHz, CDCl3, δ): 7.75 - 7.72 (m, 2H), 7.51 - 7.39 (m, 6H), 7.34 - 7.11 (m, 11H), 7.07 - 6.98 (m, 7H), 6.95 - 6.87 (m, 6H), 6.81 (t, J = 7.5 Hz, 2H), 6.74 (t, J = 7.5 Hz, 1H), 6.59 (t, J = 7.5 Hz, 1H). ASAP MS spectrum analysis: C 61 H 36 N4O theoretical value 840.29, observed value 841.47

[0094] (Synthesis Example 4) Synthesis of Comparative Compound 3 (4 - 1) Synthesis of Intermediate 7 [Chemical formula]

[0095] Under a nitrogen stream, 0.92 g (3.36 mmol) of 7H-benzo[b]thieno[2,3-b]carbazole, 1.30 g (4.20 mmol) of Intermediate 5, and 0.87 g (6.30 mmol) of potassium carbonate were added to 13 mL of dimethylformamide, and the mixture was stirred at 100 °C for 13 hours. Water was added to the reaction solution to quench it, and the suspension was filtered. The crude product was purified by silica gel column chromatography (hexane:dichloromethane = 2:3) to obtain 1.56 g (2.77 mmol, 66% yield) of Intermediate 7. 1 H NMR (500 MHz, CDCl3, δ): 8.66 (s, 1H), 8.30 - 8.26 (m, 2H), 7.84 (d, J = 8.0 Hz, 1H), 7.63 - 7.49 (m, 13H), 7.45 (d, J = 8.0 Hz, 1H), 7.40 (t, J = 7.5 Hz, 1H), 7.25 - 7.24 (m, 1H) ASAP MS spectrum analysis: C 37 H 20 F2N2S theoretical value 562.64, observed value 563.24

[0096] (4 - 2) Synthesis of Comparative Compound 3 [Chemical formula]

[0097] Under a nitrogen stream, 1.07 g (6.41 mmol) of 9H-carbazole, 1.50 g (2.67 mmol) of Intermediate 7, and 1.29 g (9.35 mmol) of potassium carbonate were added to 20 mL of dimethylformamide, and the mixture was stirred at 130 °C for 15 hours. Water was added to the reaction solution to quench it, and the suspension was filtered. The crude product was purified by silica gel column chromatography (o-dichlorobenzene), and then dissolved in o-dichlorobenzene and purified by reprecipitation with methanol to obtain 2.07 g (2.42 mmol, 90% yield) of Comparative Compound 3. 1 1H NMR (400 MHz, CDCl3, δ): 7.99 (s, 1H), 7.92 - 7.88 (m, J = 6.0, 4.3 Hz, 1H), 7.68 - 7.65 (m, J = 7.1, 2.9 Hz, 1H), 7.51 - 7.49 (m, 5H), 7.40 - 7.26 (m, 15H), 7.19 (d, J = 8.0 Hz, 2H), 7.13 (d, J = 8.0 Hz, 2H), 7.08 - 7.00 (m, 6H), 6.96 - 6.87 (m, 5H), 6.83 (t, J = 7.5 Hz, 2H), 6.74 (t, J = 7.5 Hz, 1H), 6.58 (t, J = 8.0 Hz, 1H). ASAP MS spectrum analysis: C 61 H 36 N4S theoretical value 856.27, observed value 857.44

[0098] (Examples 1 - 2, Comparative Examples 1 - 2) Preparation and evaluation of thin films On a quartz substrate, by vacuum evaporation method, under the condition of a vacuum degree of less than 1 × 10 -3 Pa, Compound 26 and PYD2Cz were evaporated from different evaporation sources, and a thin film with a thickness of 100 nm and a concentration of Compound 26 of 20 wt% was formed as the thin film of Example 1. Also, instead of Compound 26, Compound 1626, Comparative Compound 1, and Comparative Compound 2 were used to form thin films according to the same procedure. These thin films were used as the thin films of Example 2, Comparative Example 1, and Comparative Example 2 in order. For each of the obtained thin films, an emission spectrum was observed using 300 nm excitation light, and the peak wavelength (λ max ) was read. Also, the lifetime (τ d ) of delayed fluorescence was obtained from the transient decay curve of the emission observed using the same excitation light. Furthermore, ΔE ST was measured according to the following measurement method, and the photoluminescence quantum efficiency (PLQY) was also measured under a nitrogen atmosphere using 300 nm excitation light. Each measurement result was as shown in Table 3.

[0099] ΔE STis the value obtained by calculating E S1 -E T1 by determining the lowest singlet excitation energy (E S1 ) and the lowest triplet excitation energy (E T1 ) of the compound to be measured according to the following procedure. (1) Lowest singlet excitation energy (E S1 ) The fluorescence spectrum of the thin film of the compound to be measured was measured at room temperature (300 K) (vertical axis: emission intensity, horizontal axis: wavelength). A tangent was drawn to the rising edge on the short-wavelength side of this emission spectrum, and the wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis was determined. The value obtained by converting this wavelength value to an energy value using the following conversion formula was defined as E S1 . Conversion formula: E S1 [eV] = 1239.85 / λedge (2) Lowest triplet excitation energy (E T1 ) The same thin film was cooled to 77 [K] with liquid nitrogen, the sample for phosphorescence measurement was irradiated with excitation light (300 nm), and phosphorescence was measured using a detector. The emission after 100 milliseconds from the irradiation of the excitation light was defined as the phosphorescence spectrum. A tangent was drawn to the rising edge on the short-wavelength side of this phosphorescence spectrum, and the wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis was determined. The value obtained by converting this wavelength value to an energy value using the above conversion formula was defined as E T1 . The tangent to the rising edge on the short-wavelength side of the phosphorescence spectrum was drawn as follows. From the short-wavelength side of the phosphorescence spectrum, when moving along the spectrum curve to the maximum value on the shortest-wavelength side among the maximum values of the spectrum, the tangents at each point on the curve were considered in the long-wavelength direction. As the curve rises (i.e., as the vertical axis increases), the slope of this tangent increases. The tangent drawn at the point where the value of this slope reaches a maximum was defined as the tangent to the rising edge on the short-wavelength side of the phosphorescence spectrum. Note that the maximum points with peak intensities of 10% or less of the maximum peak intensity of the spectrum were not included in the above-mentioned maximum value on the shortest-wavelength side, and the tangent drawn at the point closest to the maximum value on the shortest-wavelength side where the value of the slope reaches a maximum was defined as the tangent to the rising edge on the short-wavelength side of the phosphorescence spectrum.

[0100] [Table 3]

[0101] The comparison results between Example 1 and Comparative Example 1, and the comparison results between Example 2 and Comparative Example 2 show that the ΔE of the compound of the present invention into which a carbazolyl-9-yl group condensed with a benzofuran ring is introduced ST is small, the lifetime (τ d ) of the delayed fluorescence is short, and the photoluminescence quantum efficiency (PLQY) is high.

[0102] (Examples 3 to 4) Preparation and evaluation of doped thin films with different host materials The host materials of Example 1 and Example 2 were changed from PYD2Cz to PPF, and thin films of Example 3 and Example 4 were formed according to the same procedure. When the obtained thin films were irradiated with excitation light in the same manner, delayed fluorescence was observed. The lifetimes (τ d ) of the delayed fluorescence of Example 3 and Example 4 were 12.5 μs and 18.8 μs, respectively. Also, the photoluminescence quantum efficiencies (PLQY) of Example 3 and Example 4 were 70% and 81%, respectively.

[0103] (Example 5, Comparative Example 3) Preparation and evaluation of thin films of similar luminescent materials with different constituent elements On a quartz substrate, by vapor deposition of Compound 3387 under the condition of a degree of vacuum of less than 1×10 -3 Pa, a neat thin film of Example 5 with a thickness of 100 nm was formed. Also, instead of Compound 3387, a neat thin film of Comparative Example 3 was formed according to the same procedure using Comparative Compound 3. Similar to Examples 1 to 3, when the obtained thin films were irradiated with excitation light, delayed fluorescence was observed from all the thin films. The peak wavelength (λ max) In Example 5, it was 493 nm, and in Comparative Example 3, it was 499 nm. Also, the photoluminescence quantum efficiency (PLQY) of Example 5 was 1.1 times that of Comparative Example 3. These results show that Example 5 using a compound having a carbazolyl-9-yl group condensed with a benzofuran ring has a shorter emission peak wavelength on the short-wavelength side and higher emission efficiency than Comparative Example 3 using a compound having a carbazolyl-9-yl group condensed with a benzothiophene ring. Furthermore, on a quartz substrate by vacuum deposition method, under the condition of a vacuum degree of less than 1×10 -3 Pa, Compound 3387 and PPF were deposited from different evaporation sources, and a thin film with a concentration of Compound 3387 of 20 wt% was formed with a thickness of 100 nm to obtain a doped thin film of Example 5. Also, instead of Compound 3387, Comparative Compound 3 was used, and a doped thin film of Comparative Example 3 was formed according to the same procedure. Using 300 nm excitation light, an emission transient decay curve was obtained, and the lifetime (τ d ) of the delayed fluorescence was determined. As a result, it was 11.4 μs for Comparative Example 3, while it was 7.4 μs for Example 5, which was about 30% shorter. From this, it is shown that a compound having a carbazolyl-9-yl group condensed with a benzofuran ring has a shorter lifetime of delayed fluorescence than a compound having a carbazolyl-9-yl group condensed with a benzothiophene ring.

[0104] (Examples 6 to 7) Fabrication and evaluation of organic electroluminescence devices On a glass substrate on which an anode made of indium tin oxide (ITO) with a film thickness of 100 nm was formed, each thin film was deposited by vacuum deposition method under a vacuum degree of 1×10 -6They were laminated at Pa. First, a first hole injection layer made of a first hole injection material was formed on ITO, a second hole injection layer made of a second hole injection material was formed thereon, a hole transport layer made of a hole transport material was formed thereon, and an electron blocking layer made of an electron blocking material was further formed thereon. Then, Compound 26 and a host material were co-evaporated from different evaporation sources to form a light-emitting layer with a concentration of Compound 26 of 30% by weight. Next, a hole blocking layer made of a hole blocking material was formed thereon, an electron transport layer was formed thereon, and an electrode was further formed thereon. By the above procedure, the organic electroluminescence device of Example 6 was fabricated. Also, using Compound 1626 instead of Compound 26, the organic electroluminescence device of Example 7 was fabricated by the same procedure. Each of the organic electroluminescence devices of Example 6 and Example 7 exhibits high luminous efficiency, low driving voltage, and high device lifetime (device durability). Also, by using other compounds of the present invention, it is possible to provide an organic electroluminescence device that exhibits high luminous efficiency, low driving voltage, and high device lifetime (device durability).

[0105] [Chemical formula]

Claims

1. A compound represented by the following general formula (1). 【Chemical 1】 [In general formula (1), R １ to R ５ Two of them each independently represent an aromatic hydrocarbon ring group having 6 to 14 ring backbone constituent atoms with or without substitution, R １ to R ５ Among them, the other three are donor groups, and each of the three donor groups independently represents a substituted or unsubstituted carbazolyl-9-yl group, or a carbazolyl-9-yl group condensed with a benzofuran ring. The three donor groups are not all the same, and at least one of the three donor groups is a carbazolyl-9-yl group condensed with a benzofuran ring.]

2. R １ 、 R ２ and R ４ are each independently the three donor groups, the compound according to claim 1.

3. R １ , R ３ and R ４ are each independently the three donor groups, the compound according to claim 1.

4. The compound according to any one of Claims 1 to 3, wherein two of the three donor groups are identical to each other.

5. The compound according to any one of Claims 1 to 4, wherein the carbazolyl-9-yl group condensed with the benzofuran ring has a structure in which the benzofuran ring is directly condensed to one benzene ring constituting the carbazolyl-9-yl group.

6. The compound according to Claim 5, wherein the carbazolyl-9-yl group condensed with the benzofuran ring has any of the following structures. [Chemical 2] [In each of the above structures, the hydrogen atom may be substituted.]

7. R １ to R ５ The compound according to claim 5 or 6, wherein two of them are carbazolyl-9-yl groups condensed with the benzofuran ring.

8. The compound according to Claim 7, wherein the carbazolyl-9-yl groups condensed with the two benzofuran rings are identical to each other.

9. R １ to R ５ The compound according to claim 5 or 6, wherein only one of them is a carbazolyl-9-yl group in which the benzofuran ring is condensed.

10. R １ to R ５ The compound according to any one of claims 1 to 3, wherein two of them are identical to each other.

11. A light-emitting material comprising the compound according to any one of Claims 1 to 10.

12. A light-emitting device comprising the compound according to any one of Claims 1 to 10.

13. The light-emitting device according to Claim 12, wherein the light-emitting device has a light-emitting layer, and the light-emitting layer contains the compound and a host material.

14. The light-emitting device according to Claim 12, wherein the light-emitting device has a light-emitting layer, the light-emitting layer contains the compound and a light-emitting material, and emits light mainly from the light-emitting material.

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