Organic electroluminescent device, organic EL display device, organic EL lighting, and method for manufacturing organic electroluminescent device

Abstract

The present invention relates to an organic electroluminescent element comprising a positive electrode, a negative electrode, a light-emitting layer, and a hole injection layer, wherein: the light-emitting layer is provided between the positive electrode and the negative electrode; the hole injection layer is provided between the positive electrode and the light-emitting layer; the light-emitting layer contains a polycyclic heterocyclic compound represented by formula (1); and the hole injection layer contains tetraarylborate ions. (In formula (1), the ring a, the ring b, the ring c, and Y are as defined in the description.)

Description

[Technical field]

[0001] The present invention relates to an organic electroluminescent device. [Background technology]

[0002] In recent years, organic electroluminescence devices using organic thin films have been developed as thin-film electroluminescence devices, replacing those using inorganic materials. Organic electroluminescence devices (OLEDs) usually have a hole injection layer, hole transport layer, organic light-emitting layer, electron transport layer, etc. between the anode and cathode, and materials suitable for each of these layers are being developed, and development is also underway for each of the emission colors: red, green, and blue.

[0003] In addition, methods for forming the organic layer of an organic electroluminescent device include a vacuum deposition method and a wet film-forming method (coating method). The vacuum deposition method has the advantage that lamination is easy, improving charge injection from the anode and / or cathode, and easily confining excitons in the light-emitting layer. On the other hand, the wet film-forming method has the advantages that it does not require a vacuum process, is easy to make a large area, and can easily form a layer containing multiple materials with various functions by using a coating liquid in which multiple materials with various functions are mixed. For this reason, in recent years, research and development of organic electroluminescent devices using film formation by the coating method has been actively conducted.

[0004] For example, Patent Documents 1 to 3 describe organic electroluminescent devices having a hole injection layer containing polystyrene sulfonic acid and a light-emitting layer containing a light-emitting material having a polycyclic heterocyclic compound skeleton containing boron and nitrogen. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 152418 [Patent Document 2] International Publication No. 2019 / 198699 [Patent Document 3] International Publication No. 2019 / 235452 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, polycyclic heterocyclic compounds containing boron have an empty p orbital on boron, and are easily reactive with various reactive groups. Therefore, the techniques disclosed in Patent Documents 1 to 3 do not sufficiently reduce the driving voltage of organic electroluminescent devices, and the driving life cannot be improved. The techniques disclosed in Patent Documents 1 to 3 use a hole injection layer containing a strongly acidic polystyrene sulfonic acid, and this is thought to be due to the fact that moisture and sulfonic acid groups taken in during the formation of the hole injection layer react with the polycyclic heterocyclic compound containing boron during the operation of the device.

[0007] The present invention has been made in consideration of the above-mentioned conventional circumstances, and an object of the present invention is to provide an organic electroluminescent device which has a light-emitting layer containing a polycyclic heterocyclic compound containing boron, and which has a low driving voltage and a long driving life. [Means for solving the problem]

[0008] As a result of intensive investigations, the present inventors have found that the above-mentioned problems can be solved by using a hole injection layer containing a stable tetraarylborate ion that satisfies the octet rule and does not have an empty p orbital on boron, or a crosslinked product of an electron-accepting compound having a crosslinking group, and have thus completed the present invention.

[0009] That is, the gist of the present invention is as follows. <1> ~ <28> As follows. <1> An organic electroluminescent device having an anode, a cathode, a light-emitting layer, and a hole injection layer, the light-emitting layer is provided between the anode and the cathode, the hole injection layer is provided between the anode and the light emitting layer, The light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1): The organic electroluminescent device, wherein the hole injection layer contains a tetraarylborate ion.

[0010] [ka]

[0011] (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, NR or S; R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and the Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium. <2> The tetraarylborate ion is represented by the following formula (2): <1> The organic electroluminescent device according to claim 1.

[0012] [ka]

[0013] (In formula (2), Ar 1 , Ar 2 , Ar 3 and Ar 4each independently represents a monovalent group formed by linking a plurality of structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, or an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, Ar 1 , Ar 2 , Ar 3 and Ar 4 At least one of has a fluorine atom or a fluorine-substituted alkyl group as a substituent. <3> Ar in the formula (2) 1 , Ar 2 , Ar 3 and Ar 4 At least one of the above is a group represented by the following formula (3): <2> The organic electroluminescent device according to claim 1.

[0014] [ka]

[0015] (In formula (3), R 1 each independently represents a monovalent group having a plurality of linked structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, a fluorine-substituted alkyl group, a substituent, or a crosslinking group, F4 represents four fluorine atoms. F (5-m) each independently represents a substitution of 5-m fluorine atoms, Each k independently represents an integer of 0 to 5. Each m independently represents an integer of 0 to 5. <4> In the formula (2), Ar 1 , Ar 2 , Ar 3 and Ar 4At least one of the following has the crosslinking group: <2> The organic electroluminescent device according to claim 1. <5> The crosslinking group is represented by any one of the following formulas (X1) to (X18): <4> The organic electroluminescent device according to claim 1.

[0016] [ka]

[0017] In the formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) 110 each independently represents an alkyl group. <6> The crosslinking group is represented by any one of the formulas (X1) to (X3). <5> The organic electroluminescent device according to claim 1. <7> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): <1> ~ <6> 13. The organic electroluminescent device according to claim 12,

[0018] [ka]

[0019] (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d or ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium. <8> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): <1> ~ <6> 13. The organic electroluminescent device according to claim 12,

[0020] [ka]

[0021] (In formula (71), A1 to A7 each independently represent a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group; R 71 ~R 78 each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.) <9> An organic electroluminescent device having an anode, a cathode, a light-emitting layer, and a hole injection layer, the light-emitting layer is provided between the anode and the cathode, the hole injection layer is provided between the anode and the light emitting layer, The light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1): The hole injection layer of the organic electroluminescent device contains a crosslinked product of an electron accepting compound having a crosslinking group.

[0022] [ka]

[0023] (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, NR or S; R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and the Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium. <10> The crosslinking group is represented by any one of the following formulas (X1) to (X18): <9> The organic electroluminescent device according to claim 1.

[0024] [ka]

[0025] In the formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) 110each independently represents an alkyl group. <11> The crosslinking group is represented by any one of the formulas (X1) to (X3). <10> The organic electroluminescent device according to claim 1. <12> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): <9> ~ <11> 13. The organic electroluminescent device according to claim 12,

[0026] [ka]

[0027] (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d or ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium. <13> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): <9> ~ <11> 13. The organic electroluminescent device according to claim 12,

[0028] [ka]

[0029] (In formula (71), A1 to A7 each independently represent a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group; R 71 ~R 78 each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.) <14> <1> ~ <13> 13. An organic EL display device or an organic EL lighting device comprising the organic electroluminescent device according to any one of claims 1 to 22. <15> A method for manufacturing an organic electroluminescent device having an anode, a hole injection layer, a light emitting layer, and a cathode on a substrate in this order, comprising the steps of: The method for producing the organic electroluminescent device includes forming the hole injection layer by a wet film formation method using a composition for forming the hole injection layer; forming the light-emitting layer by a wet film-forming method using a composition for forming a light-emitting layer; The composition for forming a hole injection layer contains tetraarylborate ions and an organic solvent, The composition for forming a light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1) and an organic solvent: A method for manufacturing an organic electroluminescent device.

[0030] [ka]

[0031] (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, NR or S; R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and the Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium. <16> the composition for forming a hole injection layer is a composition obtained through a process of dissolving or dispersing an electron-accepting ionic compound having a tetraarylborate ion structure and a hole transport material in an organic solvent; <15> A method for producing the organic electroluminescence device according to claim 1. <17> The tetraarylborate ion is represented by the following formula (2): <15> or <16> A method for producing the organic electroluminescence device according to claim 1.

[0032] [ka]

[0033] (In formula (2), Ar 1 , Ar 2 , Ar 3 and Ar 4each independently represents a monovalent group formed by linking a plurality of structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, or an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, Ar 1 , Ar 2 , Ar 3 and Ar 4 At least one of has a fluorine atom or a fluorine-substituted alkyl group as a substituent. <18> Ar in the formula (2) 1 , Ar 2 , Ar 3 and Ar 4 At least one of the above is a group represented by the following formula (3): <17> A method for producing the organic electroluminescence device according to claim 1.

[0034] [ka]

[0035] (In formula (3), R 1 each independently represents a monovalent group having a plurality of linked structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, a fluorine-substituted alkyl group, a substituent, or a crosslinking group, F4 represents four fluorine atoms. F (5-m) each independently represents a substitution of 5-m fluorine atoms, Each k independently represents an integer of 0 to 5. Each m independently represents an integer of 0 to 5. <19> In the formula (2), Ar 1 , Ar 2 , Ar 3 and Ar 4At least one of the following has the crosslinking group: <17> or <18> A method for producing the organic electroluminescence device according to claim 1. <20> The crosslinking group is represented by any one of the following formulas (X1) to (X18): <19> A method for producing the organic electroluminescence device according to claim 1.

[0036] [ka]

[0037] In the formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) 110 each independently represents an alkyl group. <21> The crosslinking group is represented by any one of the formulas (X1) to (X3). <20> A method for producing the organic electroluminescence device according to claim 1. <22> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): <15> ~ <21> 13. A method for producing the organic electroluminescent device according to claim 12.

[0038] [ka]

[0039] (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d or ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium. <23> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): <15> ~ <22> 13. A method for producing the organic electroluminescent device according to claim 12.

[0040] [ka]

[0041] (In formula (71), A1 to A7 each independently represent a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group; R 71 ~R 78 each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.) <24> A method for manufacturing an organic electroluminescent device having an anode, a hole injection layer, a light emitting layer, and a cathode on a substrate in this order, comprising the steps of: The method for producing the organic electroluminescent device includes forming the hole injection layer by a wet film formation method using a composition for forming the hole injection layer; forming the light-emitting layer by a wet film-forming method using a composition for forming a light-emitting layer; The composition for forming a hole injection layer includes an electron accepting compound having a crosslinking group and an organic solvent, The composition for forming a light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1) and an organic solvent: A method for manufacturing an organic electroluminescent device.

[0042] [ka]

[0043] (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, NR or S; R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and the Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium. <25> The crosslinking group is represented by any one of the following formulas (X1) to (X18): <24> A method for producing the organic electroluminescence device according to claim 1.

[0044] [ka]

[0045] In the formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) 110 each independently represents an alkyl group. <26> The crosslinking group is represented by any one of the formulas (X1) to (X3). <25> A method for producing the organic electroluminescence device according to claim 1. <27> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): <24> ~ <26> 13. A method for producing the organic electroluminescent device according to claim 12.

[0046] [ka]

[0047] (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d or ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium. <28> The polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): <24> ~ <27> 13. A method for producing the organic electroluminescent device according to claim 12.

[0048] [ka]

[0049] (In formula (71), A1 to A7 each independently represent a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group; R 71 ~R 78 each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.) Effect of the Invention

[0050] The organic electroluminescent device of the present invention exhibits excellent device characteristics, in particular, a low driving voltage and a long driving life. [Brief description of the drawings]

[0051] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the structure of an organic electroluminescent device of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0052] An organic electroluminescent device according to one embodiment of the present invention, an organic EL display device including the organic electroluminescent device, and an organic EL lighting device including the organic electroluminescent device will be described in detail below. The following description is of a first embodiment, which is one example (representative example) of an embodiment of the present invention, but the present invention is not limited to these contents as long as it does not go beyond the gist of the present invention.

[0053] <Organic electroluminescent device according to the first embodiment> The organic electroluminescent device according to the first embodiment of the present invention is an organic electroluminescent device having an anode, a cathode, a light-emitting layer, and a hole injection layer, the light-emitting layer is provided between the anode and the cathode, the hole injection layer is provided between the anode and the light emitting layer, The light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1): The hole injection layer contains tetraarylborate ions.

[0054] [ka]

[0055] (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, NR or S; R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and the Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

[0056] The reason why the organic electroluminescent device according to the first embodiment of the present invention has a low driving voltage and a long driving life is not clear, but is presumed to be as follows.

[0057] Boron-containing polycyclic heterocyclic compounds have an empty p-orbital on the boron, and are particularly susceptible to reaction with electron-donating substances. As a result of the reaction, an oxide of the electron-donating substance is produced, and this oxide may cause further degradation reactions during operation. On the other hand, tetraarylborate ions, which are stable structures that satisfy the octet rule and do not have an empty p-orbital on boron, have the effect of stabilizing cations formed by the oxidation of electron-donating substances. For this reason, it is presumed that the use of tetraarylborate ions can suppress degradation reactions during operation.

[0058] As described above, it has been found that the above problems can be solved by using a boron-containing polycyclic heterocyclic compound represented by formula (1) in an emission layer and a hole injection layer containing a stable tetraarylborate ion that satisfies the octet rule and has no vacant p orbital on boron, thereby completing the first embodiment of the present invention.

[0059] <Organic electroluminescent device according to a second embodiment> The organic electroluminescent device according to the second embodiment of the present invention is an organic electroluminescent device having an anode, a cathode, an emitting layer, and a hole injection layer, the light-emitting layer is provided between the anode and the cathode, the hole injection layer is provided between the anode and the light emitting layer, The light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1): The hole injection layer contains a crosslinked product of an electron accepting compound having a crosslinking group.

[0060] [ka]

[0061] (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, NR or S; R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and the Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

[0062] The reason why the organic electroluminescent device according to the second embodiment of the present invention has a low driving voltage and a long driving life is not clear, but is presumed to be as follows.

[0063] Boron-containing polycyclic heterocyclic compounds have vacant p-orbitals on the boron atom, making them particularly susceptible to reactions with electron-donating substances.

[0064] In general, a method is used in which an electron-accepting compound is used in the hole injection layer to promote hole injection from the metal anode and reduce the driving voltage. However, in the conventional technology, when the layer above the hole injection layer is formed by a wet film forming method, the electron-accepting compound of the hole injection layer diffuses and reaches the light-emitting layer, and the electron-accepting compound reacts with the polycyclic heterocyclic compound containing boron during device operation, which is thought to lead to an increase in driving voltage and a decrease in driving life.

[0065] On the other hand, when the electron-accepting compound contains a crosslinking group, the crosslinking reaction is advanced when the hole-injection layer is formed, and the electron-accepting compound is fixed to the hole-injection layer. When the layer above the hole-injection layer is formed by a wet film-forming method, the electron-accepting compound is not likely to diffuse. Therefore, it is presumed that the deterioration reaction during operation can be suppressed by using the electron-accepting compound having a crosslinking group.

[0066] As described above, it has been found that the above problems can be solved by using a boron-containing polycyclic heterocyclic compound represented by formula (1) in an emitting layer, forming a hole injection layer using an electron-accepting compound having a crosslinking group, and using a hole injection layer containing a crosslinked product of the electron-accepting compound having a crosslinking group, and thus the second embodiment of the present invention has been completed.

[0067] Formula (1) in the organic electroluminescent device according to the first embodiment of the present invention is similar to Formula (1) in the organic electroluminescent device according to the second embodiment of the present invention, and the preferred ranges and optional substituents are also similar.

[0068] <Polycyclic heterocyclic compounds> The light-emitting layer contains a polycyclic heterocyclic compound represented by the formula (1). The polycyclic heterocyclic compound represented by the formula (1) is preferably a light-emitting material.

[0069] (Ring a, Ring b and Ring c) Ring a, ring b and ring c are each independently an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent.

[0070] The substituent that the aromatic hydrocarbon ring or aromatic heterocycle may have is preferably a group selected from the following substituent group α.

[0071] In addition, the aromatic hydrocarbon ring or aromatic heterocycle preferably has a 5- or 6-membered ring that shares a bond with the central fused bicyclic structure of formula (1) composed of B and Y (hereinafter, may be referred to as the "central fused bicyclic structure"), and more preferably has a 6-membered ring that shares a bond with the central fused bicyclic structure of formula (1) composed of B and Y.

[0072] (Formula (1')) Here, the central fused two-ring structure of formula (1) composed of B and Y is a structure in which two saturated hydrocarbon rings composed of B and two Ys are fused together, as shown in the center of formula (1). Specifically, it is a structure in which ring d and ring e in the following formula (1') are condensed.

[0073] [ka]

[0074] In addition, the case where there is a "six-membered ring sharing a bond with the central condensed two-ring structure" means, for example, that ring a is a benzene ring (six-membered ring). "The aromatic hydrocarbon ring or aromatic heterocycle (which is ring a) has this six-membered ring" means that ring a is formed by this six-membered ring alone, or that ring a is formed by further condensing other rings to this six-membered ring so as to include this six-membered ring. The same explanation applies to "ring b", "ring c", and "five-membered ring".

[0075] Examples of the aromatic hydrocarbon ring in ring a, ring b, and ring c in formula (1) include aromatic hydrocarbon rings having 6 to 30 carbon atoms, preferably aromatic hydrocarbon rings having 6 to 16 carbon atoms, more preferably aromatic hydrocarbon rings having 6 to 12 carbon atoms, and particularly preferably aromatic hydrocarbon rings having 6 to 10 carbon atoms.

[0076] Specific examples of aromatic hydrocarbon rings include a monocyclic benzene ring, a bicyclic ...

[0077] Examples of the aromatic heterocycle in ring a, ring b, and ring c in formula (1) include aromatic heterocycles having 2 to 30 carbon atoms, preferably aromatic heterocycles having 2 to 25 carbon atoms, more preferably aromatic heterocycles having 2 to 20 carbon atoms, further preferably aromatic heterocycles having 2 to 15 carbon atoms, and particularly preferably aromatic heterocycles having 2 to 10 carbon atoms. In addition, preferred examples of the "aromatic heterocycle" include heterocycles containing, as ring-constituting atoms other than carbon, 1 to 5 heteroatoms selected from oxygen, sulfur, and nitrogen.

[0078] Specific examples of the aromatic heterocycle include a pyrrole ring, an oxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a thiadiazole ring, a triazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an indole ring, an isoindole ring, a benzimidazole ring, a benzoxazole ring, a benzothiazole ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a quinoxaline ring, a naphthyridine ring, a carbazole ring, an acridine ring, a phenoxazine ring, a phenothiazine ring, a furan ring, a benzofuran ring, a dibenzofuran ring, a thiophene ring, a benzothiophene ring, and a dibenzothiophene ring.

[0079] (substituent group α) Substituent group α is a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group, a substituted or unsubstituted diarylamino group, a substituted or unsubstituted diheteroarylamino group, a substituted or unsubstituted arylheteroarylamino group (an amino group having an aromatic hydrocarbon group and an aromatic heterocyclic group), a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a halogen atom.

[0080] The substituent that may be possessed by the group selected from the substituent group α other than halogen atoms is selected from the following substituent group β.

[0081] Examples of the aromatic hydrocarbon group or aryl structure in the substituent group α include aromatic hydrocarbon ring groups in the rings a, b, and c. Specific and preferred structures of the aromatic hydrocarbon ring are the same as those of the aromatic hydrocarbon rings in the rings a, b, and c of formula (1). The aromatic hydrocarbon group in the substituent group α is preferably a benzene ring.

[0082] Examples of the aromatic heterocyclic group or heteroaryl structure in the substituent group α include aromatic heterocyclic groups in the rings a, b, and c. The specific structure of the aromatic heterocyclic ring is the same as that of the aromatic heterocyclic ring in the rings a, b, and c of formula (1). The aromatic heterocyclic group in the substituent group α is preferably a triazine ring, a benzimidazole ring, a benzothiazole ring, a pyrimido[5,4-d]pyrimidine ring, or a benzo[1,2-d:4,5-d]diimidazole ring.

[0083] The alkyl group in the substituent group α may be either a straight chain or a branched chain, and examples thereof include straight chain alkyl groups having 1 to 24 carbon atoms and branched chain alkyl groups having 3 to 24 carbon atoms. An alkyl group having 1 to 18 carbon atoms (a branched chain alkyl group having 3 to 18 carbon atoms) is preferred, an alkyl group having 1 to 12 carbon atoms (a branched chain alkyl group having 3 to 12 carbon atoms) is more preferred, an alkyl group having 1 to 6 carbon atoms (a branched chain alkyl group having 3 to 6 carbon atoms) is further preferred, and an alkyl group having 1 to 4 carbon atoms (a branched chain alkyl group having 3 to 4 carbon atoms) is particularly preferred.

[0084] 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 sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an n-hexyl group, a 1-methylpentyl group, a 4-methyl-2-pentyl group, a 3,3-dimethylbutyl group, a 2-ethylbutyl group, an n-heptyl group, a 1-methylhexyl group, an n-octyl group, and a tert-octyl group. A part of the hydrogen atoms of the alkyl group in the substituent group α may be replaced by fluorine atoms.

[0085] Examples of the alkoxy group in the substituent group α include linear alkoxy groups having 1 to 24 carbon atoms or branched alkoxy groups having 3 to 24 carbon atoms. An alkoxy group having 1 to 18 carbon atoms (branched alkoxy group having 3 to 18 carbon atoms) is preferred, an alkoxy group having 1 to 12 carbon atoms (branched alkoxy group having 3 to 12 carbon atoms) is more preferred, an alkoxy group having 1 to 6 carbon atoms (branched alkoxy group having 3 to 6 carbon atoms) is further preferred, and an alkoxy group having 1 to 4 carbon atoms (branched alkoxy group having 3 to 4 carbon atoms) is particularly preferred.

[0086] Specific examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, and an octyloxy group.

[0087] Examples of the halogen atom in the substituent group α include a fluorine atom, a chlorine atom, and a bromine atom. A fluorine atom and a chlorine atom are preferred, and a fluorine atom is more preferred.

[0088] (substituent group β) Substituent group β is an aromatic hydrocarbon group which may be substituted with an aralkyl group, an aromatic heterocyclic group which may be substituted with an aralkyl group, an alkyl group, or a halogen atom. Examples of the aromatic hydrocarbon group, aromatic heterocyclic group, alkyl group, aralkyl group, and halogen atom in substituent group β include the same as those in substituent group α, and preferred structures are also the same as those in substituent group α.

[0089] From the viewpoint of improving stability and solubility, the substituent group β is preferably an aromatic hydrocarbon group which may be substituted with an aralkyl group, an aromatic heterocyclic group which may be substituted with an aralkyl group, an alkyl group, or an aralkyl group.

[0090] In the substituent group β, the aralkyl group, the aralkyl group which may substitute an aromatic hydrocarbon group, and the aralkyl group which may substitute an aromatic heterocyclic group are preferably aralkyl groups having 7 to 30 carbon atoms, and preferably have a structure in which a benzene ring is bonded to an alkyl group.

[0091] (Y) In formula (1), Y is O, NR or S.

[0092] (R) R is an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent. In addition, the two Y's in the formula (1) may be the same or different, but are preferably the same. The two Y's are preferably NR.

[0093] When R in formula (1) is an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, it is the same as the aromatic hydrocarbon ring group which may have a substituent or the aromatic heterocyclic group which may have a substituent in the rings a, b and c of formula (1). The specific structure and preferred structure are also the same as the aromatic hydrocarbon ring group which may have a substituent or the aromatic heterocyclic group which may have a substituent in the rings a, b and c of formula (1). When R in formula (1) is an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, the formula (1) is represented by the following formula (21). The formula (1) is preferably a structure represented by the following formula (21).

[0094] Examples of the alkyl group in R in formula (1) include the alkyl groups in the substituent group α. As the alkyl group, particularly preferred are alkyl groups having 1 to 4 carbon atoms (such as a methyl group and an ethyl group).

[0095] R is a carbon atom adjacent to the atom bonded to Y in at least one ring selected from the group consisting of the ring a, the ring b, and the ring c, and -O-, -S-, -C(-R a ) may be bonded via a 2- or single bond.

[0096] R a is a hydrogen atom or an alkyl group. R a Examples of the alkyl group in the above formula include the alkyl groups in the substituent group α. As the alkyl group, an alkyl group having 1 to 4 carbon atoms is particularly preferable, such as a methyl group or an ethyl group.

[0097] Furthermore, the adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure of formula (1) containing B and Y. At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

[0098] (Formula (21))

[0099] [ka]

[0100] (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d or ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium.

[0101] As the aromatic hydrocarbon ring group and aromatic heterocyclic group in ring f and ring g, particularly preferred are aromatic hydrocarbon ring groups having 6 to 10 carbon atoms (such as a phenyl group, a naphthyl group, etc.) and aromatic heterocyclic groups having 2 to 15 carbon atoms (such as a carbazolyl group, etc.).

[0102] The substituents that the aromatic hydrocarbon ring or aromatic heterocyclic ring, ring f and ring g, may have are the same as those for ring a, ring b and ring c, and are preferably groups selected from the aforementioned substituent group α.

[0103] (Formula (22)) The above formula (21) is preferably a structure represented by the following formula (22).

[0104] [ka]

[0105] In equation (22), In the formula (21), the ring a, the ring b, the ring c, the ring d, and the ring e are all benzene ring structures, Ring a, ring b, ring c, ring d and ring e each optionally have a substituent. Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to -O-, -S-, -C(-R a ) may be linked by a 2- or single bond, R a is a hydrogen atom or an alkyl group, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (22) may be substituted with a halogen atom or deuterium.

[0106] The substituents which the ring a, ring b, ring c, ring d, and ring e may have are the same as the substituents which the ring a, ring b, ring c, ring d, and ring e in the above formula (21) may have, and specific structures and preferred structures are also the same.

[0107] The aromatic compound represented by the formula (22) is also preferably a polycyclic heterocyclic compound represented by the formula (71) described below, or a polycyclic heterocyclic compound represented by the formula (81) described below.

[0108] The aromatic compound represented by the formula (1) is also preferably a polycyclic heterocyclic compound represented by the formula (71) described below, or a polycyclic heterocyclic compound represented by the formula (81) described below.

[0109] In addition, as the light-emitting material used in one embodiment of the present invention, a polycyclic heterocyclic compound represented by the formula (71) described later is preferable because it can provide a green-to-red light-emitting material with a long emission wavelength that can widen the color reproduction range.

[0110] In addition, as the light-emitting material used in one embodiment of the present invention, a polycyclic heterocyclic compound represented by the formula (81) described later is preferable because it can provide a blue-emitting material with a short emission wavelength that can widen the color reproduction range.

[0111] (Specific examples of polycyclic heterocyclic compounds represented by formula (1)) The structure of the polycyclic heterocyclic compound represented by formula (1) is not particularly limited, but examples thereof include the following structures.

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115] [ka]

[0116] <Polycyclic heterocyclic compound TD1> The polycyclic heterocyclic compound represented by formula (1) is also preferably a polycyclic heterocyclic compound represented by the following formula (71). In the present invention, the polycyclic heterocyclic compound represented by the following formula (71) may be referred to as polycyclic heterocyclic compound TD1.

[0117] [ka]

[0118] (In formula (71), A1 to A7 each independently represent a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group; R 71 ~R 78 each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.)

[0119] In the polycyclic heterocyclic compound represented by formula (71), the electron cloud of the LUMO is localized and collected at the position where A1 to A7 are bonded to the phenyl group. Therefore, by making at least one selected from A1 to A7 an electron-accepting substituent, the electron cloud spreads, the energy level of the LUMO is stabilized, and the energy difference between the HOMO and the LUMO is reduced. As a result, by using the polycyclic heterocyclic compound represented by formula (71), it is possible to obtain an emission spectrum with a longer wavelength.

[0120] (A1~A7) A1 to A7 each independently represent a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group.

[0121] Preferably, at least one selected from A1 to A7 is an electron accepting substituent, and A1 to A7 other than the electron accepting substituent are each independently a hydrogen atom, a fluorine atom, or an alkyl group which may have a substituent.

[0122] At least one selected from A1 to A7 is preferably an electron accepting substituent, since the emission wavelength can be adjusted by the number and type of A1 to A7. The electron-accepting substituent is a substituent of a chemical structure that is likely to become electron-excessive by withdrawing electrons from an adjacent chemical structure through a chemical bond.

[0123] Examples of the electron-accepting substituent include a heteroaryl group, a nitro group, a cyano group, an aromatic hydrocarbon group or an aromatic heterocyclic group having the above-mentioned substituent, etc. Among these, a heteroaryl group is preferable from the viewpoint of increasing the wavelength.

[0124] The heteroaryl group is an aryl group having at least one atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the heteroaryl group include groups having polycyclic aromatic heteroaryls having 1 to 4 rings containing a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, etc.

[0125] In addition, the electron-accepting substituent is preferably a group in which the absolute value of the sum of the HOMO energy level and the LUMO energy level divided by 2 (hereinafter, sometimes referred to as "absolute value α") is 3 eV or more. When the absolute value α is 3 eV or more, the electron-accepting property of the substituent is empirically improved.

[0126] The absolute value α of the electron-accepting substituent is preferably 3.1 eV or more, more preferably 3.5 eV or more, and even more preferably 4.0 eV or more. The upper limit of the absolute value α of the electron-accepting substituent is not particularly set, but is generally 7.0 eV or less.

[0127] The HOMO energy level and the LUMO energy level of the electron-accepting substituent are the HOMO molecular orbital energy level and the LUMO molecular orbital energy level obtained as follows. That is, the single bond between the electron-accepting substituent and the adjacent phenyl group in formula (1) is deleted, and a hydrogen atom is added. Then, the molecular structure of the obtained electron-accepting substituent is subjected to a structure optimization calculation by density functional using the molecular orbital calculation software Gaussian16, functional: B3LYP, and basis function: 6-31G(d).

[0128] The electron accepting substituent is preferably a group represented by the following formula (5), a group represented by the following formula (6), a group represented by the following formula (7), or a group represented by the following formula (8).

[0129] [ka]

[0130] In the formulas (5) to (8), R 732 ~R 745 each independently represents a hydrogen atom, an alkyl group which may have a substituent, or an aromatic hydrocarbon group which may have a substituent.

[0131] Examples of the alkyl group include linear, branched, or cyclic alkyl groups having 1 or more and 24 or less carbon atoms, such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, n-octyl group, cyclohexyl group, and dodecyl group.

[0132] Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 or more and 60 or less carbon atoms. Specific examples of the aromatic hydrocarbon group include monovalent groups of a 6-membered monocyclic ring or 2-5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring.

[0133] R 732 ~R 745 The substituent that may be possessed by may be selected from the substituent group Z2 described below.

[0134] Specific examples of the above formulas (5) to (8) include the following formulas (2-1) to (2-7).

[0135] [ka]

[0136] In the above formulas (2-1) to (2-7), the absolute value α obtained by calculation is as follows:

[0137] Group represented by formula (2-4): 4.35 eV Group represented by formula (2-6): 4.18 eV Group represented by formula (2-3): 4.17 eV Group represented by formula (2-7): 4.12 eV Group represented by formula (2-5): 4.10 eV Group represented by formula (2-2): 3.73 eV Group represented by formula (2-1): 3.13 eV

[0138] That is, when the same number of groups represented by the above formula (2-4), the above formula (2-6), the above formula (2-3), the above formula (2-7), the above formula (2-5), the above formula (2-2), or the above formula (2-1) are introduced into the same positions among A1 to A7 in the above formula (1), the effect of shifting the emission wavelength to longer wavelength is obtained in the order of the above formula (2-4)>the above formula (2-6)>the above formula (2-3)>the above formula (2-7)>the above formula (2-5)>the above formula (2-2)>the above formula (2-1).

[0139] Among these, the electron-accepting substituent is preferably a group represented by the above formula (5) from the viewpoints of longer wavelength and ease of production by organic synthesis.

[0140] The group represented by the above formula (5) has a relatively large absolute value α, and has little steric hindrance with the adjacent phenyl group in the above formula (71), so that the twist of the π plane between the adjacent phenyl group and the group represented by the above formula (5) is small, and the effect of increasing the wavelength of the large emission light is obtained. In addition, the group represented by the above formula (5) can be produced relatively easily in organic synthesis, and even when it is desired to improve the solubility in a solvent, R 732 , R 733 It is relatively easy to introduce a long-chain alkyl group (e.g., 4 or more carbon atoms) into the

[0141] R 732 , R 733 In addition, an alkyl group which may have a substituent is preferable because it is possible to easily obtain a long-wavelength emission wavelength by increasing the absolute value α, and also from the viewpoint of solubility in a solvent. 732 and R 733 It is more preferable that at least one selected from the group consisting of a phenyl group having a tert-butyl group.

[0142] In addition, from the viewpoint of solubility in solvents and narrowing the half-width of the emission wavelength, R 732 and R 733and the other is preferably an aromatic hydrocarbon group which may have a substituent. The substituent which the aromatic hydrocarbon group may have can be selected from the substituent group Z2.

[0143] Furthermore, A1 to A7 other than the electron accepting substituents are each independently a hydrogen atom, a fluorine atom, or an alkyl group which may have a substituent.

[0144] Examples of the alkyl group include linear, branched, or cyclic alkyl groups having 1 or more and 24 or less carbon atoms, such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, n-octyl group, cyclohexyl group, and dodecyl group.

[0145] The substituents which A1 to A7 may have can be selected from the substituent group Z2 described below.

[0146] When A1 to A7 are each independently a fluorine atom or an alkyl group which may have a substituent, the emission wavelength becomes slightly shorter or longer than when A1 to A7 are hydrogen atoms due to their electron-accepting properties. Therefore, it is preferable to select the substituent according to the target wavelength.

[0147] When a wet film-forming method is used, A1 to A7 are preferably each independently a long-chain alkyl group for the purpose of improving solubility in a solvent.

[0148] Among A1 to A7, the degree of localization of the LUMO electron cloud is not uniform, but varies depending on the position. Therefore, among A1 to A7, the positions where the effect of the electron-accepting substituent on the wavelength increase is strongest are A4>A1=A7>A3=A5>A2=A6. That is, the effect of increasing the wavelength by the electron-accepting substituent is most pronounced in A4.

[0149] Therefore, at least one selected from A1, A4, and A7 is preferably an electron accepting substituent, and more preferably a group represented by formula (5).

[0150] When both A1 and A7 are electron-accepting substituents, the effect of shifting the wavelength to a longer wavelength is approximately the same as when only A4 is the same electron-accepting substituent. In addition, it is preferable that two or more selected from A1 to A7 are electron accepting substituents in order to further increase the wavelength, and it is preferable that two or more selected from A1 to A7 are electron accepting substituents and at least one A4 is an electron accepting substituent in order to further increase the wavelength.

[0151] In addition, in formula (71), it is preferable that the single bonds connecting A1 to A7 to the adjacent phenyl groups are twisted and the π planes of the adjacent phenyl groups and the main aromatic hydrocarbon groups of the electron-accepting substituents are not twisted. This is because the twisting makes it difficult for the adjacent phenyl groups and the electron-accepting substituents to smoothly exchange charges, making it difficult to shift the emission wavelength of the above formula (71) to a longer wavelength.

[0152] (R 71 ~R 78 ) R 71 ~R 78 each independently represents a hydrogen atom, an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, an electron-donating substituent, or a combination thereof.

[0153] Examples of the alkyl group include linear, branched, or cyclic alkyl groups having 1 or more and 24 or less carbon atoms, such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, n-octyl group, cyclohexyl group, and dodecyl group.

[0154] Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 or more and 60 or less carbon atoms. Specific examples of the aromatic hydrocarbon group include monovalent groups of a 6-membered monocyclic ring or 2-5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring.

[0155] The aromatic heterocyclic group is preferably an aromatic heterocyclic group having 3 or more and 60 or less carbon atoms. Specific examples thereof include monovalent groups of 5- or 6-membered monocycles or 2- to 4-condensed rings, such as a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, and an azulene ring.

[0156] R 71 ~R 78 The substituent that may be possessed by may be selected from the substituent group Z2 described below.

[0157] Also, R 71 ~R 78 From the viewpoint of achieving longer wavelengths, it is preferable that at least one selected from the group consisting of: The electron-donating substituent is a substituent of a chemical structure that is chemically bonded to an adjacent chemical structure and thus tends to become electron deficient by donating electrons from the adjacent chemical structure.

[0158] In the polycyclic heterocyclic compound represented by formula (71), R 71 ~R 78 The HOMO electron cloud is localized and concentrated at R71 ~R 78 By using at least one of the above as an electron-donating substituent, the electron cloud of the HOMO tends to spread outward, the energy level of the HOMO becomes unstable, and the energy difference between the HOMO and the LUMO becomes small. As a result, the polycyclic heterocyclic compound represented by formula (71) can obtain an emission spectrum with a longer wavelength.

[0159] The electron-donating substituent is preferably a group having an absolute value α of less than 3 eV. When the absolute value α is less than 3 eV, the electron-donating property of the substituent is empirically improved.

[0160] The absolute value α of the electron donating substituent is more preferably less than 2.97 eV, even more preferably less than 2.8 eV, and particularly preferably less than 2.6 eV, from the viewpoint of increasing the wavelength. The lower limit of the absolute value α of the electron donating substituent is not particularly set, but is generally 1 eV or more.

[0161] The HOMO energy level and the LUMO energy level of the electron donor substituent are the HOMO molecular orbital energy level and the LUMO molecular orbital energy level obtained as follows. That is, the single bond between the electron donor substituent and the adjacent phenyl group in formula (1) is deleted, and a hydrogen atom is added. Then, the molecular structure of the obtained electron donor substituent is subjected to a structure optimization calculation by density functional using the molecular orbital calculation software Gaussian16, functional: B3LYP, and basis function: 6-31G(d).

[0162] The electron-donating substituent is preferably a group represented by the following formula (2), a group represented by the following formula (3), or a group represented by the following formula (4).

[0163] [ka]

[0164] In formulas (2) to (4), R709 ~R 731 each independently represents an alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or a hydrogen atom.

[0165] Examples of the alkyl group include linear, branched, or cyclic alkyl groups having 1 or more and 24 or less carbon atoms, such as a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, n-octyl group, cyclohexyl group, and dodecyl group.

[0166] Examples of the aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 or more and 60 or less carbon atoms. Specific examples of the aromatic hydrocarbon group include monovalent groups of a 6-membered monocyclic ring or 2-5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring.

[0167] R 709 ~R 731 The substituent that may be possessed by may be selected from the substituent group Z2 described below.

[0168] Specific examples of the above formulas (2) to (4) include the following formulas (4-1) to (4-3).

[0169] [ka]

[0170] In the above formulas (4-1) to (4-3), the absolute value α obtained by calculation is as follows:

[0171] Group represented by formula (4-3): 2.96 eV Group represented by formula (4-2): 2.91 eV Group represented by formula (4-1): 2.46 eV

[0172] That is, R in the above formula (71) 71 ~R 78 When the same number of groups represented by the above formula (4-3), the group represented by the above formula (4-2), or the group represented by the above formula (4-1) are introduced into the same positions among the above, the effect of shifting the emission wavelength to longer wavelength can be obtained in the order of formula (4-1) > formula (4-2) > formula (4-3). Also, R 71 ~R 78 It is preferable that two or more selected from the above are electron-donating substituents in order to further increase the wavelength.

[0173] Among these, the electron-donating substituent is preferably a group represented by the above formula (2) from the viewpoint of a balance between longer wavelength, ease of production by organic synthesis, and structural stability.

[0174] The group represented by the above formula (2) has a relatively small absolute value α, and has the effect of increasing the wavelength of the emitted light. In addition, the group represented by the above formula (2) can be produced relatively easily in organic synthesis, and can be used in the case where it is desired to improve the solubility in a solvent by adding R 709 ~R 716 It is relatively easy to introduce a long-chain alkyl group into the

[0175] R 709 ~R 716 From the viewpoints of solubility in a solvent and ease of synthesis, at least one selected from the above is preferably a tert-butyl group.

[0176] In addition, R 71 ~R 78 are each independently an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, or a combination thereof, R 71 ~R 78 The emission wavelength becomes slightly shorter or longer than when is a hydrogen atom, so it is preferable to select the substituent according to the desired wavelength.

[0177] In addition, when a wet deposition method is used, R71 ~R 78 is preferably each independently a long-chain alkyl group for the purpose of improving solubility in a solvent.

[0178] R 71 ~R 78 The degree to which the HOMO electron cloud is localized is not uniform, but varies depending on the position. 71 ~R 78 Among these, the position where the effect of the electron donor substituent on the wavelength increase is strongest is R 74 =R 75 >R 71 =R 78 >R 73 =R 76 >R 72 =R 77 That is, R 74 and R 75 The effect of electron donor substituents on the wavelength increase is most pronounced in the

[0179] <Dotted line> In formula (1), the dotted line may represent a single bond or no bond. The dotted line is preferably a single bond. When the dotted line is a single bond, the electron cloud spreads and the emission wavelength becomes slightly longer. In addition, when the dotted line is a single bond, the electron-accepting substituents in A1 to A7 and R 71 ~R 78 This makes it easy to introduce electron-donating substituents into the

[0180] <Symmetry of polycyclic heterocyclic compounds> The polycyclic heterocyclic compound of the formula (71) is preferably asymmetric because it has the effect of narrowing the half-width of the emission wavelength. It is considered that the half-width of the emission spectrum is narrowed because the polycyclic heterocyclic compounds are less likely to associate with each other due to the reduced symmetry of the asymmetric type, and the interaction between the polycyclic heterocyclic compounds is reduced.

[0181] The polycyclic heterocyclic compound being asymmetric means that, when the line connecting the bond axis of B and A4 in the formula (71) is taken as the rotation axis, the compound does not have the same structure when rotated 180° about the rotation axis, or that the compound does not have mirror symmetry with respect to a plane perpendicular to the plane formed by the polycyclic heterocycle of the compound of the formula (71) including the bond axis.

[0182] Specifically, a structure that satisfies at least one of the following (i) and (ii) is preferred. (i) A1 to A7, R 71 ~R 78 However, when rotated 180° about the bond axis, the structure does not become the same. (ii) A1 and A7 are different, A2 and A6 are different, A3 and A5 are different, or R 71 and R 78 are different or R 72 and R 77 are different or R 73 and R 76 are different or R 74 and R 75 But the structure is different.

[0183] <Substituent group Z2> Examples of the substituent group Z2 include the following structures. A linear, branched, or cyclic alkyl group having a carbon number of usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less; for example, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, a dodecyl group, etc. alkenyl groups having usually 2 or more carbon atoms and usually 24 or less, preferably 12 or less carbon atoms; for example, vinyl groups, An alkynyl group having usually 2 or more carbon atoms, usually 24 or less, preferably 12 or less carbon atoms; for example, an ethynyl group, etc. An alkoxy group having a carbon number of usually 1 or more and usually 24 or less, preferably 12 or less; for example, a methoxy group, an ethoxy group, etc. An aryloxy group or a heteroaryloxy group having a carbon number of usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less; for example, a phenoxy group, a naphthoxy group, a pyridyloxy group, etc. An alkoxycarbonyl group having usually 2 or more and usually 24 or less, preferably 12 or less carbon atoms; for example, a methoxycarbonyl group, an ethoxycarbonyl group, etc. A dialkylamino group having a carbon number of usually 2 or more and usually 24 or less, preferably 12 or less; for example, a dimethylamino group, a diethylamino group, etc. A diarylamino group having usually 10 or more, preferably 12 or more, and usually 36 or less, preferably 24 or less carbon atoms; for example, a diphenylamino group, a ditolylamino group, an N-carbazolyl group, etc. An arylalkylamino group having a carbon number of usually 7 or more and usually 36 or less, preferably 24 or less; for example, a phenylmethylamino group, etc. An acyl group having a carbon number of usually 2 or more and usually 24 or less, preferably 12 or less; for example, an acetyl group, a benzoyl group, etc. Halogen atoms; for example, fluorine atoms, chlorine atoms, etc. A haloalkyl group having usually 1 or more and usually 12 or less, preferably 6 or less, carbon atoms; for example, a trifluoromethyl group, etc. An alkylthio group having usually 1 or more and usually 24 or less, preferably 12 or less, carbon atoms; for example, a methylthio group, an ethylthio group, etc. An arylthio group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, carbon atoms; for example, a phenylthio group, a naphthylthio group, a pyridylthio group, etc. A silyl group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less; for example, a trimethylsilyl group, a triphenylsilyl group, etc. A siloxy group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less; for example, a trimethylsiloxy group, a triphenylsiloxy group, etc. An aromatic hydrocarbon group having a carbon number of usually 6 or more and usually 36 or less, preferably 24 or less; for example, a phenyl group, a naphthyl group, etc. Aromatic heterocyclic groups having a carbon number of usually 3 or more, preferably 4 or more, and usually 36 or less, preferably 24 or less; for example, a thienyl group, a pyridyl group, etc. Aralkyl groups having 7 or more, preferably 8 or more, and 40 or less, preferably 30 or less, and more preferably 20 or less carbon atoms; for example, a 1,1-dimethyl-1-phenylmethyl group, a 1,1-di(n-butyl)-1-phenylmethyl group, a 1,1-di(n-hexyl)-1-phenylmethyl group, a 1,1-di(n-octyl)-1-phenylmethyl group, a phenylmethyl group, a phenylethyl group, a 3-phenyl-1-propyl group, a 4-phenyl-1-n-butyl group, a 1-methyl-1-phenylethyl group, a 5-phenyl-1-n-propyl group, a 6-phenyl-1-n-hexyl group, a 6-naphthyl-1-n-hexyl group, a 7-phenyl-1-n-heptyl group, an 8-phenyl-1-n-octyl group, a 4-phenylcyclohexyl group, etc. Heteroaralkyl groups having 2 or more, preferably 4 or more, and 40 or less, preferably 30 or less, more preferably 20 or less, carbon atoms; 1,1-dimethyl-1-(2-pyridyl)methyl group, 1,1-di(n-hexyl)-1-(2-pyridyl)methyl group, (2-pyridyl)methyl group, (2-pyridyl)ethyl group, 3-(2-pyridyl)-1-propyl group, 4-(2-pyridyl)-1-n-butyl group, 1-methyl -1-(2-pyridyl)ethyl group, 5-(2-pyridyl)-1-n-propyl group, 6-(2-pyridyl)-1-n-hexyl group, 6-(2-pyrimidyl)-1-n-hexyl group, 6-(2,6-diphenyl-1,3,5-triazin-4-yl)-1-n-hexyl group, 7-(2-pyridyl)-1-n-heptyl group, 8-(2-pyridyl)-1-n-octyl group, 4-(2-pyridyl)cyclohexyl group, etc. Of these, an alkyl group, an alkoxy group, an aryloxy group, an aromatic hydrocarbon group, or an aralkyl group is preferable.

[0184] <Specific examples of polycyclic heterocyclic compounds TD1> The structure of the polycyclic heterocyclic compound TD1 represented by formula (71) is not particularly limited, but examples thereof include the following structures.

[0185] [ka]

[0186] [ka]

[0187] [ka]

[0188] [ka]

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] <Polycyclic heterocyclic compound TD2> (Formula (81)) The polycyclic heterocyclic compound represented by formula (1) is also preferably a polycyclic heterocyclic compound represented by the following formula (81). In the present invention, the polycyclic heterocyclic compound represented by the following formula (81) may be referred to as polycyclic heterocyclic compound TD2.

[0196] [ka]

[0197] [In formula (81), R 81 and the four R's 82 each independently represents a hydrogen atom, an optionally substituted alkyl group having 10 or less carbon atoms, an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms, or an optionally substituted aromatic heterocyclic group having 3 to 20 carbon atoms. A 81 represents a structure represented by the following formula (82). a80, b80, c80, and d80 each independently represent an integer of 0 to 2, and at least one of a80 to d80 is an integer of 1 or more. In equation (81), A 81 If there are multiple A's, multiple A's 81 may be the same or different.]

[0198] [ka]

[0199] [In formula (82), an asterisk (*) represents a bond, R F represents a fluoroalkyl group having 5 or less carbon atoms, R 83 represents an optionally substituted alkyl group having 10 or less carbon atoms, an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms, or an optionally substituted aromatic heterocyclic group having 3 to 20 carbon atoms. e80 represents an integer from 0 to 5. The two R in equation (82) F may be the same or different. In addition, in formula (82), R 83 If there are multiple R 83 may be the same or different.]

[0200] (Why formula (81) is preferred) The polycyclic heterocyclic compound represented by the formula (81) has a basic skeleton of a fused heterocyclic skeleton containing a boron atom and a nitrogen atom, and is characterized in that at least one quaternary carbon atom substituted with two fluoroalkyl groups and a benzene ring, represented by the formula (82), is connected to this basic skeleton.

[0201] If a fluorine atom is directly substituted into the basic skeleton, the emission wavelength will be shortened, but the ionization potential and electron affinity of the compound will change significantly. Therefore, when the compound is applied as a light-emitting material for an organic electroluminescent device, the charge balance of the device will be lost, making it difficult to achieve excellent device characteristics.

[0202] In contrast, in the polycyclic heterocyclic compound of the present invention, a fluorine atom, which is a strong electron-withdrawing group, is not directly substituted on the basic skeleton, and therefore it is possible to achieve a shorter emission wavelength without significantly varying the ionization potential and electron affinity, which have a significant effect on the device characteristics of an organic electroluminescent device.

[0203] In addition, the quaternary carbon atom in the formula (82) connected to the basic skeleton has an asymmetric structure in which two fluoroalkyl groups and a benzene ring are bonded, so that the polycyclic heterocyclic compound of the present invention has excellent solubility in an organic solvent. Therefore, the film formed by the wet film formation method has high uniformity and is suitable as a light-emitting material for an organic electroluminescent device.

[0204] <R 81 and R 82 > R in equation (81) 81 and the four R's 82each independently represents a hydrogen atom, an optionally substituted alkyl group having 10 or less carbon atoms, an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms, or an optionally substituted aromatic heterocyclic group having 3 to 20 carbon atoms.

[0205] Examples of alkyl groups having 10 or less carbon atoms include methyl, ethyl, and branched, straight-chain or cyclic propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl and adamantyl groups. 1 When is an alkyl group having 10 or less carbon atoms, from the viewpoint of the stability of the compound, a methyl group, a branched, linear or cyclic propyl group, or a butyl group is preferable, and a branched butyl group is particularly preferable.

[0206] Examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include monovalent groups such as a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, a chrysene ring, a pyrene ring, a benzoanthracene ring, and a perylene ring. From the viewpoint of the solubility of the compound, a phenyl group, which is a monovalent group of a benzene ring, is preferred.

[0207] Examples of aromatic heterocyclic groups having 3 to 20 carbon atoms include monovalent groups such as a pyridine ring, a quinoline ring, a benzofuran ring, and a carbazole ring.

[0208] R 81 is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a t-butyl group.

[0209] R 82 is preferably a hydrogen atom.

[0210] <a80~d80> In formula (81), a80, b80, c80, and d80 each independently represent an integer of 0 to 2, and at least one of a80 to d80 is an integer of 1 or greater. From the viewpoint of the short wavelength of the emission wavelength of the compound, a80+b80+c80+d80 is preferably 2 or greater, and a80+b80+c80+d80 is particularly preferably 4 or greater.

[0211] <R F > In formula (82), R F represents a fluoroalkyl group having 5 or less carbon atoms. Examples of the fluoroalkyl group having 5 or less carbon atoms include a trifluoromethyl group, a pentafluoroethyl group, and a perfluoroalkyl group such as a branched, linear or cyclic perfluoropropyl group, a perfluorobutyl group, or a perfluoropentane group. From the viewpoint of the film-forming property of the compound, a trifluoromethyl group or a pentafluoroethyl group is preferred, and a trifluoromethyl group is particularly preferred.

[0212] <R 83 > In formula (82), R 83 represents an alkyl group having 10 or less carbon atoms which may have a substituent, an aromatic hydrocarbon group having 6 to 20 carbon atoms which may have a substituent, or an aromatic heterocyclic group having 3 to 20 carbon atoms which may have a substituent. Examples of the alkyl group having 10 or less carbon atoms include a methyl group, an ethyl group, and a branched, linear or cyclic propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, and a decyl group. From the viewpoint of the solubility of the compound, a branched or linear propyl group, a butyl group, a pentyl group, and a hexyl group are preferred, and a branched or linear butyl group and a branched, linear or cyclic hexyl group are particularly preferred.

[0213] Examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include monovalent groups such as a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, a chrysene ring, a pyrene ring, a benzoanthracene ring, and a perylene ring. From the viewpoint of the solubility of the compound, a phenyl group, which is a monovalent group of a benzene ring, is preferred.

[0214] Examples of aromatic heterocyclic groups having 3 to 20 carbon atoms include monovalent pyridine rings, quinoline rings, benzofuran rings, and carbazole rings.

[0215] <R 81 ~R 83 The substituent that may be present in R 81 , R 82 , R 83 is an alkyl group having 10 or less carbon atoms which may have a substituent, an aromatic hydrocarbon group having from 6 to 20 carbon atoms which may have a substituent, or an aromatic heterocyclic group having from 3 to 20 carbon atoms which may have a substituent, the substituent that the alkyl group, aromatic hydrocarbon group, or aromatic heterocyclic group may have can be selected, for example, from substituent group W1 which will be described later.

[0216] Among these, preferred are alkyl groups having 10 or less carbon atoms, aromatic hydrocarbon groups or aromatic heterocyclic groups having 20 or less carbon atoms, and aralkyl groups having 30 or less carbon atoms, and more preferred are alkyl groups having 10 or less carbon atoms, aromatic hydrocarbon groups having 20 or less carbon atoms, and aralkyl groups having 30 or less carbon atoms.

[0217] Examples of the alkyl group having 10 or less carbon atoms as a substituent include a methyl group, an ethyl group, and a branched, linear, or cyclic propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, and a decyl group. From the viewpoint of the stability of the compound, a methyl group, an ethyl group, a branched, linear, or cyclic propyl group, or a butyl group is preferred, and a branched propyl group is particularly preferred.

[0218] Examples of the aromatic hydrocarbon group having 6 to 20 carbon atoms as a substituent include monovalent groups such as a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, a chrysene ring, a pyrene ring, a benzoanthracene ring, and a perylene ring. From the viewpoint of the solubility of the compound, a phenyl group, which is a monovalent group of a benzene ring, is preferred.

[0219] Examples of the aromatic heterocyclic group having 3 to 20 carbon atoms as a substituent include monovalent groups such as a pyridine ring, a quinoline ring, a benzofuran ring, and a carbazole ring.

[0220] Examples of aralkyl groups having 30 or less carbon atoms as a substituent include benzyl, 2-phenylethyl, 2-phenylpropyl-2-yl, 2-phenylbutyl-2-yl, 3-phenylpentyl-3-yl, 3-phenyl-1-propyl, 4-phenyl-1-butyl, 5-phenyl-1-pentyl, 6-phenyl-1-hexyl, 7-phenyl-1-heptyl, and 8-phenyl-1-octyl groups.

[0221] <Substituent group W1> Examples of the substituent group W1 include the following structures. For example, linear, branched, or cyclic alkyl groups having a carbon number of usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, or a dodecyl group; For example, an alkenyl group having usually 2 or more carbon atoms and usually 24 or less, preferably 12 or less, such as a vinyl group; For example, an alkynyl group having typically 2 or more carbon atoms and typically 24 or less, preferably 12 or less, such as an ethynyl group; For example, aralkyl groups having 30 or less carbon atoms, such as benzyl group, 2-phenylethyl group, 2-phenylpropyl-2-yl group, 2-phenylbutyl-2-yl group, 3-phenylpentyl-3-yl group, 3-phenyl-1-propyl group, 4-phenyl-1-butyl group, 5-phenyl-1-pentyl group, 6-phenyl-1-hexyl group, 7-phenyl-1-heptyl group, and 8-phenyl-1-octyl group; For example, an alkoxy group having usually 1 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methoxy group or an ethoxy group; For example, an aryloxy group or heteroaryloxy group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, such as a phenoxy group, a naphthoxy group, or a pyridyloxy group; For example, alkoxycarbonyl groups having usually 2 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methoxycarbonyl group or an ethoxycarbonyl group; For example, dialkylamino groups having usually 2 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a dimethylamino group or a diethylamino group; For example, diarylamino groups having usually 10 or more, preferably 12 or more, and usually 36 or less, preferably 24 or less, such as a diphenylamino group, a ditolylamino group, or an N-carbazolyl group; For example, an arylalkylamino group, such as a phenylmethylamino group, which usually has 7 or more carbon atoms and usually has 36 or less, preferably 24 or less carbon atoms; For example, acyl groups such as an acetyl group and a benzoyl group, each of which usually has 2 or more carbon atoms and usually has 24 or less, preferably 12 or less carbon atoms; For example, halogen atoms such as fluorine atoms and chlorine atoms; For example, haloalkyl groups having typically 1 or more and typically 12 or less, preferably 6 or less, carbon atoms, such as a trifluoromethyl group; For example, an alkylthio group having usually 1 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methylthio group or an ethylthio group; For example, an arylthio group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, such as a phenylthio group, a naphthylthio group, or a pyridylthio group; For example, a silyl group having usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsilyl group or a triphenylsilyl group; For example, a siloxy group having usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsiloxy group or a triphenylsiloxy group; Cyano group; For example, aromatic hydrocarbon groups such as a phenyl group and a naphthyl group, each of which usually has 6 or more carbon atoms and usually has 36 or less, and preferably has 24 or less carbon atoms; For example, aromatic heterocyclic groups having usually 3 or more, preferably 4 or more, and usually 36 or less, preferably 24 or less, such as a thienyl group or a pyridyl group.

[0222] Among the above-mentioned substituent group W1, an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group is preferable, and an alkyl group or an aromatic hydrocarbon group is more preferable. From the viewpoint of charge transportability, it is more preferable that the compound has no substituent.

[0223] Each of the substituents in the above-mentioned substituent group W1 may further have a substituent, and as the substituent, the same ones as those in the above-mentioned substituent group W1 can be used.

[0224] <Preferable polycyclic heterocyclic compound TD2> The polycyclic hetero compound TD2 represented by the above formula (81) preferably has a structure represented by the following formula (83).

[0225] [ka]

[0226] [In formula (83), R 81 , R 82 , A 81 is R in Eq. (81) 81 , R 82 , A 81 is synonymous with a83, b83, c83 and d83 each independently represent 0 or 1, and at least one of them represents 1.

[0227] That is, in the formula (81), A 81 In the basic skeleton not substituted with, the HOMO is distributed on the carbon atom at the para position of the nitrogen atom (= the meta position of the boron atom), so if this carbon atom is substituted with A as in the structure represented by formula (83), the effect of shortening the wavelength is large, which is preferable. From this point of view, it is preferable that all of a83 to d83 in the above formula (83) are 1.

[0228] <Specific examples of polycyclic heterocyclic compounds TD2> Specific examples of the polycyclic heterocyclic compound TD2 of the present invention represented by formula (81) are shown below, but the present invention is not limited thereto.

[0229] [ka]

[0230] [Host material] The light-emitting layer preferably further contains a host material. The host material is preferably a charge-transporting host material, and can be a material that has been used in the past for organic electroluminescent devices. For example, pyridine, carbazole, naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, coumarin, p-bis(2-phenylethenyl)benzene and derivatives thereof, quinacridone derivatives, DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran)-based compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, condensed aromatic ring compounds substituted with an arylamino group, and styryl derivatives substituted with an arylamino group can be mentioned.

[0231] These may be used alone or in any combination and ratio of two or more kinds.

[0232] Of these, preferred are naphthalene, perylene, pyrene, anthracene, chrysene, naphthacene, phenanthrene, coronene, fluoranthene, benzophenanthrene, fluorene, acetonaphthofluoranthene, and derivatives thereof, and more preferred are anthracene derivatives.

[0233] (Anthracene derivatives) The anthracene derivative is preferably a compound represented by the following formula (30).

[0234] [ka]

[0235] In the above formula (30), Ar 241 , Ar 242 are each independently a structure represented by the following formula (31), and Ar 243 represents a substituent, and Ar 243 When there are multiple, they may be the same or different, and n 43 is an integer from 0 to 8.

[0236] [ka]

[0237] In the above formula (31), Ar 244 , Ar 245 each independently represents an aromatic hydrocarbon structure which may have a substituent, or a heteroaromatic ring structure which may have a substituent; Ar 244 , Ar 245 When multiple are present, they may be the same or different, and n 44 is an integer between 1 and 5, n 45 is an integer between 0 and 5.

[0238] Ar 244 is preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 30 carbon atoms and which may have a substituent, and more preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 12 carbon atoms and which may have a substituent. Specifically, the aromatic hydrocarbon structure is more preferably a benzene ring structure, a naphthalene structure, an anthracene structure, or a phenanthrene structure, and further preferably a benzene ring structure.

[0239] Ar 245is preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 30 carbon atoms which may have a substituent, or an aromatic heterocyclic structure which is a fused ring having 6 to 30 carbon atoms which may have a substituent, and more preferably an aromatic hydrocarbon structure which is a monocyclic or fused ring having 6 to 12 carbon atoms which may have a substituent, or an aromatic heterocyclic structure which is a fused ring having 12 carbon atoms which may have a substituent. Specifically, the aromatic hydrocarbon structure is more preferably a benzene ring structure, a naphthalene structure, an anthracene structure, or a phenanthrene structure, and the aromatic heterocyclic structure is more preferably a dibenzofuran structure, a dibenzothiophene structure, or a phenanthroline structure, and the aromatic hydrocarbon structure is still more preferably a benzene ring structure, a naphthalene structure, or a phenanthrene structure, and the aromatic heterocyclic structure is still more preferably a dibenzofuran structure or a phenanthroline structure.

[0240] n 44 is preferably an integer of 1 to 3, more preferably 1 or 2, and n 45 is preferably 0 to 3, and more preferably 0 to 2.

[0241] (Ar 243 , Ar 244 , Ar 245 (Substituents of The substituent Ar 243 and Ar 244 and Ar 245 The substituent which may be possessed by is preferably a group selected from the following substituent group Z, more preferably an alkyl group or an aromatic hydrocarbon group included in the substituent group Z, and further preferably an aromatic hydrocarbon group included in the substituent group Z.

[0242] (Substituent group Z) The substituent group Z is a group consisting of an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, a heteroaryloxy group, an alkoxycarbonyl group, a dialkylamino group, a diarylamino group, an arylalkylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. These substituents may have any of a linear, branched, and cyclic structure.

[0243] More specifically, the substituent group Z includes the following structures. For example, linear, branched, or cyclic alkyl groups having a carbon number of usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, further preferably 8 or less, and more preferably 6 or less, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, or a dodecyl group; linear, branched, or cyclic alkenyl groups, such as, for example, vinyl groups, which usually have 2 or more carbon atoms and usually have 24 or less carbon atoms, preferably 12 or less carbon atoms; For example, a linear or branched alkynyl group, such as an ethynyl group, which usually has 2 or more carbon atoms and usually has 24 or less carbon atoms, preferably 12 or less carbon atoms; For example, alkoxy groups having carbon atoms of usually 1 or more and usually 24 or less, preferably 12 or less, such as a methoxy group or an ethoxy group; For example, an aryloxy group or heteroaryloxy group having a carbon number of usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, such as a phenoxy group, a naphthoxy group, or a pyridyloxy group; For example, alkoxycarbonyl groups having usually 2 or more and usually 24 or less, and preferably 12 or less, carbon atoms, such as a methoxycarbonyl group or an ethoxycarbonyl group; For example, dialkylamino groups having usually 2 or more and usually 24 or less, and preferably 12 or less, carbon atoms, such as a dimethylamino group or a diethylamino group; For example, diarylamino groups having usually 10 or more, preferably 12 or more, and usually 36 or less, preferably 24 or less, such as a diphenylamino group and a ditolylamino group; For example, an arylalkylamino group having typically 7 or more and typically 36 or less, preferably 24 or less, carbon atoms, such as a phenylmethylamino group; For example, acyl groups such as an acetyl group and a benzoyl group, each of which usually has 2 or more carbon atoms and usually has 24 or less carbon atoms, and preferably has 12 or less carbon atoms; For example, halogen atoms such as fluorine atoms and chlorine atoms; For example, haloalkyl groups having typically 1 or more and typically 12 or less, preferably 6 or less, carbon atoms, such as a trifluoromethyl group; For example, an alkylthio group having usually 1 or more and usually 24 or less, preferably 12 or less, carbon atoms, such as a methylthio group or an ethylthio group; For example, an arylthio group having usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, such as a phenylthio group, a naphthylthio group, or a pyridylthio group; For example, a silyl group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsilyl group or a triphenylsilyl group; For example, a siloxy group having a carbon number of usually 2 or more, preferably 3 or more, and usually 36 or less, preferably 24 or less, such as a trimethylsiloxy group or a triphenylsiloxy group; Cyano group; For example, aromatic hydrocarbon groups such as a phenyl group and a naphthyl group, each of which usually has 6 or more and usually has 36 or less, and preferably has 24 or less carbon atoms; For example, aromatic heterocyclic groups having usually 3 or more, preferably 4 or more, and usually 36 or less, preferably 24 or less, such as a thienyl group or a pyridyl group.

[0244] Among the above-mentioned substituent group Z, preferred are alkyl groups, alkoxy groups, diarylamino groups, aromatic hydrocarbon groups, or aromatic heterocyclic groups. From the viewpoint of charge transportability, preferred are aromatic hydrocarbon groups or aromatic heterocyclic groups, and more preferred are those that do not have a substituent. From the viewpoint of improving solubility, preferred are alkyl groups or alkoxy groups.

[0245] Each of the substituents in the above-mentioned substituent group Z may further have a substituent. Examples of the substituent include the same ones as those in the above-mentioned substituent group Z. Each of the substituents that the above-mentioned substituent group Z may have is preferably an alkyl group having 8 or less carbon atoms, an alkoxy group having 8 or less carbon atoms, or a phenyl group, more preferably an alkyl group having 6 or less carbon atoms, an alkoxy group having 6 or less carbon atoms, or a phenyl group, and from the viewpoint of charge transportability, each of the substituents in the above-mentioned substituent group Z more preferably does not have an additional substituent.

[0246] (molecular weight) The compound represented by the formula (30) is a low molecular weight material, and its molecular weight is preferably 3,000 or less, more preferably 2,500 or less, particularly preferably 2,000 or less, and most preferably 1,500 or less, and is usually 300 or more, preferably 350 or more, and more preferably 400 or more.

[0247] (Specific examples of anthracene derivatives represented by formula (30)) The structure of the anthracene derivative represented by the formula (30) is not particularly limited, but for example, the following structure is preferred.

[0248] [ka]

[0249] [ka]

[0250] [ka]

[0251] [ka]

[0252] [ka]

[0253] [ka]

[0254] [ka]

[0255] [ka]

[0256] [Composition for forming light-emitting layer] The method for forming the light-emitting layer may be either a vacuum deposition method or a wet film formation method, but is preferably a wet film formation method. In the wet film formation method, the light-emitting layer is formed by coating and drying a composition for forming a light-emitting layer containing an organic solvent.

[0257] The composition for forming a light-emitting layer contains the polycyclic heterocyclic compound represented by the formula (1) and an organic solvent. The composition for forming a light-emitting layer preferably further contains a host material.

[0258] (Organic solvent) The organic solvent contained in the composition for forming a light-emitting layer is a volatile liquid component used for forming a layer containing a polycyclic heterocyclic compound by wet film formation.

[0259] The organic solvent is not particularly limited as long as it is an organic solvent in which the polycyclic heterocyclic compound and the charge transporting compound, which are solutes, can be dissolved well.

[0260] Preferred organic solvents include, for example, alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, and bicyclohexane; aromatic hydrocarbons such as toluene, xylene, mesitylene, phenylcyclohexane, tetralin, and methylnaphthalene; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene; and aromatic hydrocarbons such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, and diphenyl ether. aromatic ethers; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate; alicyclic ketones such as cyclohexanone, cyclooctanone, and fenchone; alicyclic alcohols such as cyclohexanol and cyclooctanol; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; aliphatic alcohols such as butanol and hexanol; and aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA).

[0261] Among these, from the viewpoints of viscosity and boiling point, alkanes, aromatic hydrocarbons, and aromatic esters are preferred, and aromatic hydrocarbons and aromatic esters are particularly preferred.

[0262] These organic solvents may be used alone or in any combination of two or more in any ratio.

[0263] The boiling point of the organic solvent used is usually 80° C. or higher, preferably 100° C. or higher, more preferably 120° C. or higher, and usually 350° C. or lower, preferably 330° C. or lower, more preferably 300° C. or lower. If the boiling point of the organic solvent is below this range, the film formation stability may decrease during wet film formation due to solvent evaporation from the composition for forming the light-emitting layer. If the boiling point of the organic solvent is above this range, the film formation stability may decrease during wet film formation due to solvent remaining after film formation.

[0264] In particular, it is preferable to combine two or more of the above organic solvents having a boiling point of 150° C. or higher, since this is believed to facilitate the formation of a more uniform coating film.

[0265] (Content) The content of the polycyclic heterocyclic compound represented by formula (1) in the composition for forming the light-emitting layer is usually 0.001% by mass or more, preferably 0.01% by mass or more, usually 30.0% by mass or less, preferably 20.0% by mass or less. The content of the compound represented by formula (30) in the composition for forming the light-emitting layer is usually 0.01% by mass or more, preferably 0.1% by mass or more, usually 30.0% by mass or less, preferably 20.0% by mass or less. By setting the content within this range, holes and electrons are efficiently injected from adjacent layers (e.g., hole transport layer and hole blocking layer) to the light-emitting layer, and the driving voltage can be reduced. Note that the polycyclic heterocyclic compound represented by formula (1) may be contained in the composition for forming the light-emitting layer by only one type, or may be contained in a combination of two or more types.

[0266] The content of the host material in the composition for forming a light-emitting layer is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually 30.0% by mass or less, preferably 20.0% by mass or less.

[0267] The content of the host material in the composition for forming an emitting layer is usually 1,000 parts by mass or less, preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, relative to 1 part by mass of the polycyclic heterocyclic compound represented by formula (1), and is usually 0.01 part by mass or more, preferably 0.1 part by mass or more, and more preferably 1 part by mass or more.

[0268] The content of the organic solvent contained in the composition for forming a light-emitting layer is usually 10% by mass or more, preferably 50% by mass or more, particularly preferably 80% by mass or more, and usually 99.95% by mass or less, preferably 99.9% by mass or less, particularly preferably 99.8% by mass or less. If the content of the organic solvent is equal to or more than the lower limit, the composition has a suitable viscosity and improves the coatability, and if the content is equal to or less than the upper limit, the composition is easy to obtain a uniform film and has good film formability.

[0269] (Other Ingredients) The composition for forming a light-emitting layer may further contain other compounds in addition to the above compounds, as necessary. As the other compounds, preferably, phenols such as dibutylhydroxytoluene and dibutylphenol, which are known as antioxidants, can be mentioned.

[0270] (Film forming method) The method for forming the light-emitting layer is preferably a wet film-forming method. The wet film-forming method is a method in which a composition is applied to form a liquid film, and the liquid film is dried to remove the organic solvent to form a film of the light-emitting layer. As the coating method, for example, a method for forming a film by a wet method such as a spin coating method, a dip coating method, a die coating method, a bar coating method, a blade coating method, a roll coating method, a spray coating method, a capillary coating method, an inkjet method, a nozzle printing method, a screen printing method, a gravure printing method, or a flexographic printing method is adopted, and the coating film is dried to form a film. Among these coating methods, the spin coating method, the spray coating method, the inkjet method, the nozzle printing method, and the like are preferred. When manufacturing an organic EL display device equipped with an organic electroluminescent element, the inkjet method or the nozzle printing method is preferred, and the inkjet method is particularly preferred.

[0271] The drying method is not particularly limited, and may be, for example, natural drying, drying under reduced pressure, drying by heating, or drying under reduced pressure while heating. Drying by heating may be performed after natural drying or drying under reduced pressure in order to further remove the remaining organic solvent.

[0272] The drying under reduced pressure is preferably carried out at a pressure lower than the vapor pressure of the organic solvent contained in the composition for forming a light-emitting layer.

[0273] When heating, the heating method is not particularly limited, but it is possible to use heating on a hot plate, heating in an oven, infrared heating, etc. The heating time is usually 80° C. or more, preferably 100° C. or more, more preferably 110° C. or more, and preferably 200° C. or less, more preferably 150° C. or less.

[0274] The heating time is usually 1 minute or more, preferably 2 minutes or more, and usually 60 minutes or less, preferably 30 minutes or less, more preferably 20 minutes or less.

[0275] [Hole injection layer] The hole injection layer must have the function of transporting holes, and therefore contains a hole transport material.

[0276] In order to improve the hole injection from the anode to the hole injection layer and improve the hole transport in the hole injection layer, the hole transport material contained in the hole injection layer preferably contains a cation radical site. In order to convert the hole transport material into a cation radical, an electron accepting compound is used when forming the hole injection layer. As the backbone of the electron accepting compound, an ionic compound consisting of a tetraarylborate ion, which is an anion with an ionic valence of 1 described later, and a counter cation is preferable because it has high stability.

[0277] The hole transport material is converted into a cation radical as follows: When a compound having a triarylamine structure is used as the hole transport material, and a tetraarylborate salt having a diaryliodonium as a counter cation is used as the electron accepting compound, the counter cation can change from diaryliodonium to triarylaminium as shown in the following formula when the hole injection layer is formed.

[0278] [ka]

[0279] (For example, Ar, Ar 1 ~Ar 4are each independently an aromatic hydrocarbon group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a monovalent group in which a plurality of structures selected from an aromatic hydrocarbon ring group which may have a substituent and an aromatic heterocyclic group which may have a substituent are linked together.

[0280] The triarylaminium produced in the above reaction has a half-occupied molecular orbital (SOMO) capable of accepting electrons, and therefore the tetraarylborate salt having the triarylaminium as the counter cation is an electron-accepting compound.

[0281] In the present invention, the compound consisting of the cation of the hole transport material and the anion, tetraarylborate ion, is called a charge transporting ionic compound, as will be described in detail later.

[0282] [Electron-accepting compounds having bridging groups] As the electron-accepting compound, there can be mentioned compounds having a parent skeleton of an ionic compound consisting of a tetraarylborate ion and a counter cation, as described above.

[0283] (crosslinking group) The crosslinking group of the electron-accepting compound forming the crosslinked product of the electron-accepting compound having a crosslinking group contained in the hole injection layer of the organic electroluminescent device according to the second embodiment of the present invention means a group that reacts with another group located in the vicinity of the crosslinking group by irradiation with heat and / or active energy rays to form a new chemical bond. In this case, the reactive group may be the same as or different from the crosslinking group.

[0284] The crosslinking group is preferably a crosslinking group represented by any one of the following formulas (X1) to (X18).

[0285] [ka]

[0286] (In the formulas (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. The substituents may also be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) 110 each independently represents an alkyl group which may have a substituent.

[0287] R 110 The alkyl group represented by the formula (I) has a linear, branched or cyclic structure and has 1 or more carbon atoms and preferably 24 or less, more preferably 12 or less, and further preferably 8 or less.

[0288] Benzene rings and naphthalene rings of the formulae (X1) to (X4), R 110 The substituent which may be contained in the alkyl group is preferably an alkyl group, an aromatic hydrocarbon group, an alkyloxy group, or an aralkyl group.

[0289] The alkyl group as a substituent has a straight-chain, branched or cyclic structure and preferably has 24 or less carbon atoms, more preferably 12 or less, further preferably 8 or less, and preferably 1 or more carbon atoms.

[0290] The number of carbon atoms in the aromatic hydrocarbon group as a substituent is preferably 24 or less, more preferably 18 or less, even more preferably 12 or less, and preferably 6 or more. The aromatic hydrocarbon group may further have the above-mentioned alkyl group as a substituent.

[0291] The alkyloxy group as a substituent has preferably 24 or less carbon atoms, more preferably 12 or less, further preferably 8 or less, and preferably 1 or more.

[0292] The number of carbon atoms in the aralkyl group as a substituent is preferably 30 or less, more preferably 24 or less, further preferably 14 or less, and preferably 7 or more. The alkylene group contained in the aralkyl group preferably has a straight chain or branched structure. The aryl group contained in the aralkyl group may further have the above-mentioned alkyl group as a substituent.

[0293] As the crosslinking group, a crosslinking group represented by any one of formulas (X1) to (X3) is preferable in that the crosslinking reaction proceeds only by heat, the polarity is small, and the effect on charge transport is small.

[0294] In the crosslinking group represented by formula (X1), as shown in the following formula, the cyclobutene ring is opened by heat, and the ring-opened groups bond to each other to form a crosslinked structure.

[0295] [ka]

[0296] In the crosslinking group represented by formula (X2), as shown in the following formula, the cyclobutene ring is opened by heat, and the ring-opened groups bond to each other to form a crosslinked structure.

[0297] [ka]

[0298] In the crosslinking group represented by formula (X3), as shown in the following formula, the cyclobutene ring is opened by heat, and the ring-opened groups bond to each other to form a crosslinked structure.

[0299] [ka]

[0300] In the crosslinking group represented by any one of formulas (X1) to (X3), the cyclobutene ring is opened by heat, and if a double bond is present in the vicinity of the ring-opened group, the ring-opened group reacts with the double bond to form a crosslinked structure. Below is an example in which a crosslinked structure is formed by a group obtained by ring-opening the crosslinking group represented by formula (X1) and a crosslinking group represented by formula (X4) having a double bond site. (However, R in formula (X4) 110 is not shown.)

[0301] [ka]

[0302] Examples of the double bond-containing group capable of reacting with the crosslinking group represented by any one of formulae (X1) to (X3) include the crosslinking group represented by formula (X4) and the crosslinking group represented by any one of formulae (X5), (X6), (X12), (X15), (X16), (X17) and (X18). When using these double bond-containing groups as the crosslinking group in the electron-accepting compound, it is preferable to incorporate the crosslinking group represented by any one of formulae (X1) to (X3) in other components forming the hole-injecting layer, such as the hole-transporting compound, since this increases the possibility of forming a crosslinked structure.

[0303] As the crosslinking group, a radically polymerizable crosslinking group represented by any one of the formulae (X4), (X5) and (X6) is preferable since it has a small polarity and is unlikely to interfere with charge transport.

[0304] As the crosslinking group, a crosslinking group represented by formula (X7) is preferred in terms of enhancing electron-accepting property. When the crosslinking group represented by formula (X7) is used, the following crosslinking reaction proceeds.

[0305] [ka]

[0306] The crosslinking group represented by either formula (X8) or (X9) is preferred in terms of high reactivity. When the crosslinking group represented by formula (X8) or the crosslinking group represented by formula (X9) is used, the following crosslinking reaction proceeds.

[0307] [ka]

[0308] As the crosslinking group, a cationic polymerizable crosslinking group represented by any one of the formulae (X10), (X11) and (X12) is preferred in terms of high reactivity.

[0309] (Crosslinked product of electron-accepting compound) As described later, the hole injection layer of the organic electroluminescent device of the present invention is preferably obtained by wet film formation of a composition for forming a hole injection layer, and the composition for forming a hole injection layer is preferably a composition obtained by a process of dissolving or dispersing a first ionic compound having a tetraarylborate ion structure described later and a hole transport material described later in an organic solvent. The hole transport layer of the organic electroluminescent device of the present invention preferably contains a charge transporting ionic compound having the tetraarylborate ion structure of the present invention described later as an anion and a cation of the hole transport material as a counter cation.

[0310] Therefore, the electron-accepting compound in the electron-accepting compound having a crosslinking group is preferably an ionic compound, and the ionic compound as the electron-accepting compound is preferably an ionic compound having a tetraarylborate ion structure as an anion. When the electron-accepting compound is an ionic compound having a tetraarylborate ion structure as an anion, it is preferable that the tetraarylborate ion has a crosslinking group. The tetraarylborate ion structure will be described later.

[0311] Therefore, the crosslinked product of the electron-accepting compound having a crosslinking group includes the following crosslinked products. A compound in which electron-accepting compounds are bridged together. A compound in which an electron-accepting compound and a hole-transporting material are crosslinked. A compound in which an electron-accepting compound is crosslinked with the tetraarylborate ion of the present invention. A compound in which tetraarylborate ions in the present invention are crosslinked with each other. A compound in which the tetraarylborate ion of the present invention is crosslinked with a hole transport material.

[0312] Here, the term "tetraarylborate ion in the present invention" includes a case where it exists as an electron-accepting compound, which is an ionic compound consisting of a tetraarylborate ion described below and a counter cation, and a case where it exists as a charge-transporting ionic compound consisting of a tetraarylborate ion described below and a cation of a hole-transporting material.

[0313] The two crosslinking groups that undergo a crosslinking reaction may be the same or different, so long as they are capable of crosslinking.

[0314] [Tetraarylborate ion] A tetraarylborate ion is a monovalent anion in which a boron atom is substituted with four aromatic hydrocarbon rings, which may have substituents and / or bridging groups, or four aromatic heterocycles, which may have substituents and / or bridging groups.

[0315] The tetraarylborate ion contained in the organic electroluminescent device of the present invention preferably has a fluorine atom or a fluorine-substituted alkyl group as a substituent of the aryl group in terms of further improving stability. That is, it is preferably represented by the following formula (2).

[0316] [ka]

[0317] (In formula (2), Ar 1 , Ar 2 , Ar 3 and Ar 4 each independently represents a monovalent group formed by linking a plurality of structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, or an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, Ar 1 , Ar 2 , Ar 3 and Ar 4 At least one of has a fluorine atom or a fluorine-substituted alkyl group as a substituent.

[0318] Ar 1 , Ar 2 , Ar 3 and Ar 4At least one of them preferably has a crosslinking group.

[0319] Ar 1 , Ar 2 , Ar 3 and Ar 4 The aromatic hydrocarbon ring group used in is preferably a single ring or 2 to 6 condensed rings, specifically, a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, a biphenyl structure, a terphenyl structure, or a quaterphenyl structure.

[0320] Ar 1 , Ar 2 , Ar 3 and Ar 4 The aromatic heterocyclic group used in is preferably a single ring or 2 to 6 condensed rings.Specific examples thereof include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring.

[0321] Among these, a monovalent group derived from a benzene ring, a naphthalene ring, a fluorene ring, a pyridine ring or a carbazole ring, or a biphenyl group is more preferred because of its excellent stability and heat resistance. A monovalent group derived from a benzene ring, that is, a phenyl group or a biphenyl group, is particularly preferred.

[0322] The total number of monocyclic or 2-6 condensed ring aromatic hydrocarbon ring groups and monocyclic or 2-6 condensed ring aromatic heterocyclic groups contained in a monovalent group in which a plurality of structures selected from aromatic hydrocarbon ring groups which may have a substituent and / or a crosslinking group and aromatic heterocyclic groups which may have a substituent and / or a crosslinking group are linked together is 2 or more and preferably 8 or less, more preferably 4 or less, and even more preferably 3 or less.

[0323] Ar 1 , Ar 2 , Ar 3 and Ar 4 Examples of the substituent that may be possessed by include the groups described in the substituent group W described below.

[0324] Ar 1 , Ar 2 , Ar 3 and Ar 4 The substituent of is preferably a fluorine atom or a fluorine-substituted alkyl group, since it increases the stability of the anion and improves the effect of stabilizing the cation. 1 , Ar 2 , Ar 3 and Ar 4 Of these, it is preferable that two or more of the groups are substituted, more preferable that three or more of the groups are substituted, and most preferable that four of the groups are substituted.

[0325] Ar 1 , Ar 2 , Ar 3 and Ar 4 The fluorine-substituted alkyl group as the substituent is preferably a linear or branched alkyl group having 1 to 12 carbon atoms substituted with a fluorine atom, more preferably a perfluoroalkyl group, still more preferably a linear or branched perfluoroalkyl group having 1 to 5 carbon atoms, particularly preferably a linear or branched perfluoroalkyl group having 1 to 3 carbon atoms, and most preferably a perfluoromethyl group. The reason for this is that the hole injection layer containing the crosslinked product of the electron-accepting compound having a tetraarylborate ion or a crosslinking group, and the coating film laminated thereon, become stable.

[0326] Ar 1 , Ar 2 , Ar 3 and Ar 4 The crosslinking group which may be possessed by the formula (I) is as described above.

[0327] The tetraarylborate ion contained in the organic electroluminescent device of the present invention is preferably Ar 1 , Ar 2 , Ar 3 and Ar 4 is preferably a group represented by formula (3), and Ar 1 , Ar 2 , Ar 3 and Ar 4 It is more preferable that at least two of the groups are each independently represented by formula (3), and Ar 1 , Ar 2 , Ar 3 and Ar 4 It is more preferable that at least three of the groups are each independently represented by formula (3), and Ar 1 , Ar 2 , Ar 3 and Ar 4 It is most preferable that all of them are each independently a group represented by formula (3).

[0328] [ka]

[0329] (In formula (3), R 1 each independently represents a monovalent group having a plurality of linked structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, a fluorine-substituted alkyl group, a substituent, or a crosslinking group, F4 represents four fluorine atoms. F (5-m) each independently represents a substitution of 5-m fluorine atoms, Each k independently represents an integer of 0 to 5. Each m independently represents an integer of 0 to 5.

[0330] In terms of further improving the stability of the anion, k is preferably 1 or more, and more preferably 2 or more. In terms of facilitating uniform dispersion, k is preferably 0 or 1, and more preferably 0.

[0331] m is preferably 0 in terms of superior durability, is preferably 1 or more in terms of enabling various functions to be introduced into the tetraarylborate ion, and is more preferably 1 or 2 in terms of compatibility with durability. From the viewpoint of improving the stability of the anion and providing excellent durability, it is preferable that k+m≧1.

[0332] R 1 As the aromatic hydrocarbon ring group or aromatic heterocyclic group, preferred structures and optional substituents are: 1 , Ar 2 , Ar 3 and Ar 4 The structure and the substituents that may be possessed by the above-mentioned alkyl group are the same as those of the above-mentioned alkyl group.

[0333] R 1 The substituents and R 1 When is a substituent, examples of the substituent include the groups described in the substituent group W below.

[0334] In the formula (3), at least one R 1 is preferably the above-mentioned fluorine-substituted alkyl group, more preferably a perfluoroalkyl group, and more preferably a trifluoromethyl group.

[0335] R 1 The bridging group and R 1 When is a crosslinking group, the crosslinking group is as defined above.

[0336] In formula (3), at least one R 1 It is preferable that R contains the crosslinking group in order to achieve both crosslinking and electron accepting properties. 1 is preferably the above-mentioned crosslinking group or a structure in which one or more of the above-mentioned crosslinking groups are bonded to the aromatic hydrocarbon group.

[0337] In addition, R 1 is also preferably a group containing a group represented by the following formula (4) or a group represented by the following formula (5).

[0338] [ka]

[0339] The group represented by formula (4) and the group represented by formula (5) may have a substituent. Examples of the substituent include R 1 The substituents are the same as those that may be possessed by the group.

[0340] R 1 is preferably a group represented by formula (4) or (5), or a structure in which one or more groups represented by formula (4) or (5) are bonded to an aromatic hydrocarbon group.

[0341] R 1 However, when one or more of the crosslinking groups are bonded to the aromatic hydrocarbon group, the aromatic hydrocarbon group is preferably a structure in which two or more rings selected from a benzene ring, a naphthalene ring, or a benzene ring and a naphthalene ring are bonded to each other, and the number of bonds is preferably 4 or less. 1 is a structure in which the crosslinking group is bonded to a monocyclic benzene ring or a monocyclic naphthalene ring, more preferably a structure in which the crosslinking group is bonded to a benzene ring, and particularly preferably a structure in which one or two crosslinking groups are bonded.

[0342] R 1is a group represented by formula (4) or a group containing a group represented by the following formula (5), more preferable R 1 is a structure in which a group represented by formula (4) or a group represented by formula (5) is bonded to a monocyclic benzene ring or a monocyclic naphthalene ring, more preferably a structure in which a group represented by formula (4) or a group represented by formula (5) is bonded to a benzene ring, and particularly preferably a structure in which one or two groups represented by formula (4) or (5) are bonded to the benzene ring.

[0343] The group represented by the formula (4) and the group represented by the formula (5) are preferred because they have crosslinking properties and it is believed that the tetraarylborate ion and the counter cation do not diffuse into other layers.

[0344] (Substituent group W) The substituent group W is a hydrogen atom, a halogen atom, a cyano group, an aromatic hydrocarbon ring group consisting of 1 to 5 aromatic hydrocarbon rings, an aliphatic hydrocarbon ring group, an alkyl group, an alkenyl group, an alkynyl group, an aralkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkyl ketone group, or an aryl ketone group.

[0345] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms, and a fluorine atom is preferred from the viewpoint of compound stability. From the viewpoint of compound stability, it is particularly preferred that four or more fluorine atoms are substituted.

[0346] Examples of the aromatic hydrocarbon group consisting of 1 to 5 aromatic hydrocarbon rings include a phenyl group, a biphenyl group, a terphenyl group, a quaterphenyl group, a naphthyl group, a phenanthrenyl group, a triphenylene group, and a naphthylphenyl group, of which a phenyl group, a naphthyl group, a biphenyl group, a terphenyl group, or a quaterphenyl group is preferred in terms of the stability of the compound.

[0347] Examples of the aliphatic hydrocarbon ring group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0348] The alkyl group has a carbon number of usually 1 or more, preferably 4 or more, and usually 24 or less, preferably 12 or less, further preferably 8 or less, and more preferably 6 or less. Specific examples include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a cyclohexyl group, an octyl group, a 2-ethylhexyl group, and a dodecyl group.

[0349] The alkenyl group has a carbon number of usually 2 or more and usually 24 or less, preferably 12 or less. Specific examples include a vinyl group, a propenyl group, and a butenyl group.

[0350] The alkynyl group has usually 2 or more and usually 24 or less, and preferably 12 or less, carbon atoms. Specific examples thereof include an acetyl group, a propynyl group, and a butynyl group.

[0351] Examples of the aralkyl group include a benzyl group, a phenylethyl group, and a phenylhexyl group.

[0352] The alkoxy group has a carbon number of usually 1 or more and usually 24 or less, preferably 12 or less, and more preferably 6 or less. Specific examples include a methoxy group, an ethoxy group, a butyloxy group, a hexyloxy group, and an octyloxy group.

[0353] The aryloxy group has a carbon number of usually 4 or more, preferably 5 or more, and more preferably 6 or more, and usually 36 or less, preferably 24 or less, and more preferably 12 or less. Specific examples include a phenoxy group, a naphthyloxy group, and the like.

[0354] The alkylthio group has usually 1 or more and usually 24 or less, and preferably 12 or less, and specific examples include a methylthio group, an ethylthio group, a butylthio group, and a hexylthio group.

[0355] The arylthio group has usually 4 or more, preferably 5 or more, and usually 36 or less, preferably 24 or less, and specific examples include a phenylthio group, a naphthylthio group, and the like.

[0356] The alkyl ketone group has a carbon number of usually 1 or more and usually 24 or less, preferably 12 or less, and more preferably 6 or less. Specific examples include an acetyl group, an ethylcarbonyl group, a butylcarbonyl group, and an octylcarbonyl group.

[0357] The aryl ketone group has usually 5 or more, preferably 7 or more, and usually 25 or less, preferably 13 or less, and specific examples include a benzoyl group, a naphthylcarbonyl group, and the like.

[0358] Adjacent substituents may be bonded to each other to form a ring. Examples of the ring include a cyclobutene ring and a cyclopentene ring.

[0359] These substituents may further be substituted with a substituent, and examples of the substituent include a halogen atom, an alkyl group, an aryl group, or the above-mentioned crosslinking group.

[0360] Among these substituents, a halogen atom or an aryl group is preferred in terms of the stability of the compound, and a halogen atom is most preferred, with a fluorine atom being most preferred among halogen atoms.

[0361] [Examples of tetraarylborate ions] Specific examples of the tetraarylborate ion used in the organic electroluminescent device of the present invention are listed below, but the invention is not limited thereto.

[0362] [ka]

[0363]

change

[0364]

change

[0365]

change

[0366]

change

[0367]

change

[0368]

change

[0369]

change

[0370]

change

[0371]

change

[0372] Among the above specific examples, in terms of electron-accepting property, heat resistance, and solubility, the compounds (A-1) and (A-2) are preferred.Furthermore, in terms of high stability as a composition for charge transport film, the compounds (A-18), (A-19), (A-20), (A-21), (A-25), (A-26), and (A-28) are more preferred, and in terms of stability of organic electroluminescent device, the compounds (A-19), (A-21), (A-25), (A-26), and (A-28) are particularly preferred.

[0373] The tetraarylborate ions (A-18), (A-19), (A-20), (A-21), (A-25), (A-26), (A-28), and (A-29) have crosslinking groups and can therefore form "crosslinked products of electron-accepting compounds."

[0374] [Electron-accepting ionic compounds containing tetraarylborate ions] The tetraarylborate ion is also preferably used as an electron-accepting ionic compound containing the tetraarylborate ion. The electron-accepting ionic compound containing the tetraarylborate ion is referred to as a first ionic compound. The first ionic compound is composed of the tetraarylborate ion, which is an anion, and a counter cation. The first ionic compound is used as an electron-accepting compound.

[0375] The counter cation is preferably an iodonium cation, a sulfonium cation, a carbocation, an oxonium cation, an ammonium cation, a phosphonium cation, a cycloheptyltrienyl cation, or a ferrocenium cation having a transition metal, more preferably an iodonium cation, a sulfonium cation, a carbocation, or an ammonium cation, and particularly preferably an iodonium cation.

[0376] The iodonium cation is preferably a structure represented by the general formula (6) described later, and the same also applies to more preferred structures.

[0377] Specific examples of preferred iodonium cations include diphenyliodonium cation, bis(4-tert-butylphenyl)iodonium cation, 4-tert-butoxyphenylphenyliodonium cation, 4-methoxyphenylphenyliodonium cation, and 4-isopropylphenyl-4-methylphenyliodonium cation.

[0378] Specific examples of the sulfonium cation include triphenylsulfonium cation, 4-hydroxyphenyldiphenylsulfonium cation, 4-cyclohexylphenyldiphenylsulfonium cation, 4-methanesulfonylphenyldiphenylsulfonium cation, (4-tert-butoxyphenyl)diphenylsulfonium cation, bis(4-tert-butoxyphenyl)phenylsulfonium cation, and 4-cyclohexylsulfonylphenyldiphenylsulfonium cation.

[0379] Specific examples of the carbocation include tri-substituted carbocations such as triphenyl carbocation, tri(methylphenyl) carbocation, and tri(dimethylphenyl) carbocation.

[0380] Specific examples of the ammonium cation include trialkylammonium cations such as trimethylammonium cation, triethylammonium cation, tripropylammonium cation, tributylammonium cation, and tri(n-butyl)ammonium cation; N,N-dialkylanilinium cations such as N,N-diethylanilinium cation and N,N-2,4,6-pentamethylanilinium cation; and dialkylammonium cations such as di(isopropyl)ammonium cation and dicyclohexylammonium cation.

[0381] Specific examples of the phosphonium cation include tetraarylphosphonium cations such as tetraphenylphosphonium cation, tetrakis(methylphenyl)phosphonium cation, and tetrakis(dimethylphenyl)phosphonium cation; and tetraalkylphosphonium cations such as tetrabutylphosphonium cation and tetrapropylphosphonium cation.

[0382] Among these, in terms of the film stability of the compound, iodonium cation, carbocation and sulfonium cation are preferred, with iodonium cation being more preferred.

[0383] The iodonium cation serving as the counter cation of the first ionic compound is preferably a structure represented by the following formula (6).

[0384] [ka]

[0385] In formula (6), Ar 5 , Ar 6 Each of Ar independently represents an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. 5 , Ar 6 The aromatic hydrocarbon ring group or aromatic heterocyclic group as Ar 1 , Ar 2 , Ar 3 and Ar 4 The same structures can be selected as in the case of Ar 1 , Ar 2 , Ar 3 and Ar 4 The same structures can be selected as in the case of

[0386] The counter cation represented by the formula (6) is preferably represented by the following formula (7).

[0387] [ka]

[0388] In the above formula (7), Ar 7 and Ar 8 is the Ar 5 and Ar 6 The substituents are the same as those that may be possessed by the group.

[0389] The molecular weight of the first ionic compound used in the present invention is usually 900 or more, preferably 1000 or more, more preferably 1200 or more, and usually 10000 or less, preferably 5000 or less, more preferably 3000 or less. If the molecular weight is too small, the delocalization of positive and negative charges is insufficient, and the electron accepting ability may decrease, whereas if the molecular weight is too large, charge transport may be hindered.

[0390] [Specific example] Specific examples of ionic compounds with iodonium cations will be given below as the first ionic compound in the present invention, but the first ionic compound is not limited to these.

[0391] [ka]

[0392] [ka]

[0393] [ka]

[0394] [ka]

[0395] [ka]

[0396] [ka]

[0397] [ka]

[0398] [ka]

[0399] [ka]

[0400] [ka]

[0401] [ka]

[0402] [ka]

[0403] [ka]

[0404] Among the above specific examples, in terms of electron accepting property, heat resistance, and solubility, the compounds (B-1) and (B-2) are preferred.Furthermore, in terms of high stability as a composition for charge transport film, the compounds (B-18), (B-19), (B-20), (B-21), (B-25), (B-26), (B-28), and (B-29) are more preferred, and in terms of stability of organic electroluminescent device, the compounds (B-19), (B-21), (B-25), (B-26), (B-28), and (B-29) are particularly preferred.

[0405] [Hole transport material] The hole injection layer preferably contains a hole transport material, and is preferably formed using a hole transport material. As the hole transport material, a compound having an ionization potential of 4.5 eV to 5.5 eV is preferable in terms of hole transport ability. Examples include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, etc. Among them, aromatic amine compounds are preferable in terms of amorphousness, solubility in solvents, and visible light transmittance.

[0406] Among the aromatic amine compounds, aromatic tertiary amine compounds are particularly preferred in the present invention. The aromatic tertiary amine compound in the present invention is a compound having an aromatic tertiary amine structure, and includes compounds having a group derived from an aromatic tertiary amine.

[0407] The type of aromatic tertiary amine compound is not particularly limited, but aromatic tertiary amine polymer compound, which is a polymer compound, is preferred.From the viewpoint of surface smoothing effect, the molecular weight of the polymer compound is preferably 5000 or more, more preferably 7000 or more, particularly preferably 10000 or more, and preferably 1000000 or less, more preferably 200000 or less, particularly preferably 100000 or less.Among aromatic tertiary amine polymer compounds, from the viewpoint of hole transportability, polymer compounds having triphenylamine structure in the main chain are more preferred.

[0408] [Aromatic tertiary amine polymer compounds] A preferred example of the aromatic tertiary amine polymer compound is a polymer compound having a repeating unit represented by the following formula (11).

[0409] [ka]

[0410] In the above formula (11), j 10 , k 10 , l 10 , m 10 , n10 , p 10 Each independently represents an integer of 0 or more. 10 +m 10 ≧1.

[0411] In the above formula (11), Ar 11 , Ar 12 , Ar 14 each independently represents a divalent aromatic ring group which may have a substituent. 13 represents a divalent aromatic ring group which may have a substituent or a divalent group represented by the following formula (12), Q 11 , Q 12 each independently represents an oxygen atom, a sulfur atom, or a hydrocarbon chain having 6 or less carbon atoms which may have a substituent; S 1 ~S 4 are each independently represented by a group represented by the following formula (13).

[0412] Ar 11 , Ar 12 , Ar 14 The aromatic ring group of Ar represents a divalent aromatic hydrocarbon group which may have a substituent, a divalent aromatic heterocyclic group which may have a substituent, or a divalent group in which at least two groups selected from a divalent aromatic hydrocarbon group which may have a substituent and a divalent aromatic heterocyclic group which may have a substituent are linked together. 11 , Ar 12 , Ar 14 The aromatic ring group preferably has 60 or less carbon atoms.

[0413] The aromatic hydrocarbon group preferably has 6 or more and 30 or less carbon atoms, and specific examples thereof include divalent groups of a 6-membered monocyclic ring or 2-5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring.

[0414] The aromatic heterocyclic group preferably has 3 or more and 30 or less carbon atoms. Specific examples thereof include divalent groups such as a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring.

[0415] Among these, a divalent group derived from a benzene ring, a naphthalene ring, a fluorene ring, a pyridine ring or a carbazole ring, or a divalent biphenyl group is preferred because of its excellent charge transport properties, durability and heat resistance, and a divalent group derived from a benzene ring, a fluorene ring or a carbazole ring, or a divalent biphenyl group is more preferred.

[0416] Therefore, Ar 11 , Ar 12 , Ar 14 is preferably a group selected from a divalent benzene ring which may have a substituent, a divalent fluorene ring which may have a substituent, or a divalent carbazole ring which may have a substituent, or a divalent group in which two or more rings selected from these structures are linked together, and Ar 11 , Ar 12 , Ar 14 The aromatic ring group preferably has 60 or less carbon atoms.

[0417] These aromatic ring groups may have a substituent, and the substituent that may be had may be selected from the above-mentioned substituent group Z.

[0418] Ar 13 When is an aromatic ring group, Ar 11 , Ar 12 , Ar14 The same is true for Ar 13 is also preferably a divalent group represented by the following formula (12).

[0419] [ka]

[0420] In the above formula (12), R 11 R represents an alkyl group, an aromatic ring group, or a trivalent group consisting of an alkyl group having 40 or less carbon atoms and an aromatic ring group, which may have a substituent. 12 represents an alkyl group, an aromatic ring group, or a divalent group consisting of an alkyl group having 40 or less carbon atoms and an aromatic ring group, which may have a substituent. 31 represents a monovalent aromatic ring group or a monovalent bridging group, and these groups may have a substituent. An asterisk (*) represents a bond to the nitrogen atom of formula (11).

[0421] R 11 Specific examples of the aromatic ring group include a phenyl ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a trivalent group derived from a connecting ring having 30 or less carbon atoms formed by connecting these rings.

[0422] R 11 Specific examples of the alkyl group include trivalent groups derived from methane, ethane, propane, isopropane, butane, isobutane, and pentane.

[0423] R 12 Specific examples of the aromatic ring group include a phenyl ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a divalent group derived from a connecting ring having 30 or less carbon atoms formed by connecting these rings.

[0424] R 12 Specific examples of the alkyl group include divalent groups derived from methane, ethane, propane, isopropane, butane, isobutane, and pentane.

[0425] Ar 31 Specific examples of the aromatic ring group include a phenyl ring, a naphthalene ring, a carbazole ring, a dibenzofuran ring, a dibenzothiophene ring, and a monovalent group derived from a connecting ring having 30 or less carbon atoms formed by connecting these rings.

[0426] Ar 31 The crosslinking group is not particularly limited, but is the same as the crosslinking group of the electron-accepting compound having the crosslinking group contained in the hole injection layer of the organic electroluminescent device of the present invention, and is preferably a crosslinking group represented by any one of the formulas (X1) to (X18). Among them, preferred are groups derived from a benzocyclobutene ring, a naphthocyclobutene ring, or an oxetane ring, a vinyl group, and an acrylic group. From the viewpoint of compound stability, a group derived from a benzocyclobutene ring or a naphthocyclobutene ring is more preferred.

[0427] S 1 ~S 4 each independently represents a group represented by the following formula (13):

[0428] [ka]

[0429] In the above formula (13), q and r each independently represent an integer of 0 to 6. Each of q and r independently is preferably 0 to 4, and more preferably 0 or 1.

[0430] Ar 21 , Ar 23 Each of the groups independently represents a divalent aromatic ring group, and these groups may have a substituent. 22 represents a monovalent aromatic ring group which may have a substituent, R 13 represents an alkyl group, an aromatic ring group, or a divalent group consisting of an alkyl group and an aromatic ring group, which may have a substituent. 32 represents a monovalent aromatic ring group or a monovalent bridging group, and these groups may have a substituent. An asterisk (*) represents a bond to the nitrogen atom of general formula (11).

[0431] Ar 21 , Ar 23 Examples of aromatic ring groups include Ar 11 , Ar 12 , Ar 14 The same is true for

[0432] Ar 22 , Ar 32 The aromatic ring group of Ar represents a monovalent aromatic hydrocarbon group which may have a substituent, a monovalent aromatic heterocyclic group which may have a substituent, or a monovalent group in which at least two groups selected from a monovalent aromatic hydrocarbon group which may have a substituent and a monovalent aromatic heterocyclic group which may have a substituent are linked together. 22 , Ar 32 The aromatic ring group preferably has 60 or less carbon atoms.

[0433] The aromatic hydrocarbon group preferably has 6 or more and 30 or less carbon atoms, and specific examples thereof include monovalent groups of a 6-membered monocyclic ring or 2-5 condensed rings, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, or a fluorene ring.

[0434] The aromatic heterocyclic group preferably has 3 or more and 30 or less carbon atoms. Specific examples thereof include monovalent groups such as a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, a carbazole ring, a pyrroloimidazole ring, a pyrrolopyrazole ring, a pyrrolopyrrole ring, a thienopyrrole ring, a thienothiophene ring, a furopyrrole ring, a furofuran ring, a thienofuran ring, a benzisoxazole ring, a benzisothiazole ring, a benzimidazole ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, or an azulene ring.

[0435] Among these, a monovalent group derived from a benzene ring, a naphthalene ring, a fluorene ring, a pyridine ring or a carbazole ring, or a biphenyl group is preferred because of its excellent charge transporting property, durability and heat resistance.

[0436] These aromatic ring groups may have a substituent, and the substituent that may be had may be selected from the above-mentioned substituent group Z.

[0437] R 13 Examples of the alkyl group or aromatic ring group include R 12 is the same as:

[0438] Ar 32 The bridging group is not particularly limited, but may be Ar 31 The examples and preferred examples of the bridging group are the same as those of the bridging group of the above.

[0439] The above Ar 11 ~Ar 14 , R 11 , R 12 , Ar 21 ~Ar 23 , Ar 31 ~Ar 32 , Q 11 , Q 12 Each of the above may further have a substituent, provided that it is not contrary to the spirit of the present invention. The molecular weight of the substituent is usually 400 or less, and preferably about 250 or less. The type of the substituent is not particularly limited, and examples thereof include one or more types selected from the above-mentioned substituent group Z.

[0440] In particular, among the polymer compounds having a repeating unit represented by formula (11), a polymer compound having a repeating unit represented by the following formula (14) is preferred because it has extremely high hole injection / transport properties.

[0441] [ka]

[0442] In the above formula (14), R 21 ~R25 Each independently represents an arbitrary substituent. 21 ~R 25 Specific examples of the substituent are the same as those described in the above-mentioned substituent group Z.

[0443] Y' represents a divalent aromatic ring group having 30 or less carbon atoms which may have a substituent. Examples of the aromatic ring group of Y' include the above-mentioned Ar 11 , Ar 12 and Ar 14 The same applies to the substituents that the group may have.

[0444] Each of s and t independently represents an integer of 0 to 5. Each of u, v, and w independently represents an integer of 0 to 4.

[0445] Preferred examples of the aromatic tertiary amine polymeric compound include polymeric compounds containing repeating units represented by the following formula (15) and / or formula (16).

[0446] [ka]

[0447] In the above formula (15) and formula (16), Ar 45 , Ar 47 and Ar 48 each independently represents a monovalent aromatic hydrocarbon group which may have a substituent or a monovalent aromatic heterocyclic group which may have a substituent. 44 and Ar 46 R each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. 41 ~R 43 each independently represents a hydrogen atom or an arbitrary substituent, and r is an integer of 0 to 2.

[0448] Ar 45 , Ar 47 and Ar 48Specific examples, preferred examples, examples of the substituents which may be present, and preferred examples of the substituents are each independently represented by Ar 22 and Ar 32 The same is true for

[0449] Ar 44 and Ar 46 Specific examples, preferred examples, examples of the substituents which may be present, and preferred examples of the substituents are each independently represented by Ar 11 and Ar 14 The same is true for

[0450] R 41 ~R 43 is preferably a hydrogen atom or a substituent described in the above-mentioned substituent group Z, and among these, preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group, an aromatic hydrocarbon group, or an aromatic heterocyclic group.

[0451] r is preferably 0 or 1, and more preferably 0.

[0452] Preferred specific examples of the repeating units represented by formula (15) and formula (16) that can be used in the present invention are given below, but the present invention is not limited to these.

[0453] [ka]

[0454] Other examples of aromatic amine compounds that can be used as hole transport materials include conventionally known compounds that have been used as materials for forming layers with hole injection and transport properties in organic electroluminescent devices. For example, aromatic diamine compounds in which tertiary aromatic amine units such as 1,1-bis(4-di-p-tolylaminophenyl)cyclohexane are linked (JP Patent Publication No. 59-194393); aromatic amines containing two or more tertiary amines, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, in which two or more condensed aromatic rings are substituted with nitrogen atoms (JP Patent Publication No. 5-234681); aromatic triamines that are derivatives of triphenylbenzene and have a starburst structure (US Patent Publication No. 5-234681); No. 4,923,774; aromatic diamines such as N,N'-diphenyl-N,N'-bis(3-methylphenyl)biphenyl-4,4'-diamine (U.S. Pat. No. 4,764,625); α,α,α',α'-tetramethyl-α,α'-bis(4-di-p-tolylaminophenyl)-p-xylene (JP Patent Publication No. 3-269084); triphenylamine derivatives which are stereochemically asymmetric as a whole molecule (JP Patent Publication No. 4-129271); aromatic diamino groups attached to pyrenyl groups Compounds with multiple substitutions (JP Patent Publication No. 4-175395); aromatic diamines in which tertiary aromatic amine units are linked by ethylene groups (JP Patent Publication No. 4-264189); aromatic diamines having a styryl structure (JP Patent Publication No. 4-290851); aromatic tertiary amine units linked by thiophene groups (JP Patent Publication No. 4-304466); starburst type aromatic triamines (JP Patent Publication No. 4-308688); benzylphenyl compounds (JP Patent Publication No. 4-364 153); fluorene groups linked to tertiary amines (JP Patent Publication No. 5-25473); triamine compounds (JP Patent Publication No. 5-239455); bisdipyridylaminobiphenyls (JP Patent Publication No. 5-320634); N,N,N-triphenylamine derivatives (JP Patent Publication No. 6-1972); aromatic diamines having a phenoxazine structure (JP Patent Publication No. 7-138562); diaminophenylphenanthridine derivatives (JP Patent Publication No. 7-252474);Examples of the aromatic amine compounds include hydrazone compounds (JP Patent Publication 2-311591); silazane compounds (US Pat. No. 4,950,950); silanamine derivatives (JP Patent Publication 6-49079); phospamine derivatives (JP Patent Publication 6-25659); and quinacridone compounds. Two or more of these aromatic amine compounds may be mixed and used as necessary.

[0455] Another specific example of an aromatic amine compound that can be used as a hole transport material is a metal complex of an 8-hydroxyquinoline derivative having a diarylamino group. The central metal of the metal complex is selected from alkali metals, alkaline earth metals, Sc, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Al, Ga, In, Si, Ge, Sn, Sm, Eu, and Tb, and the ligand 8-hydroxyquinoline has one or more diarylamino groups as substituents, but may have any substituent other than the diarylamino group.

[0456] Preferable specific examples of the phthalocyanine derivative or porphyrin derivative applicable as a hole transport material include porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphyrin, 5,10,15,20-tetraphenyl-21H,23H-porphyrin cobalt(II), 5,10,15,20-tetraphenyl-21H,23H-porphyrin copper(II), 5,10,15,20-tetraphenyl-21H,23H-porphyrin zinc(II), Examples of suitable phthalocyanine compounds include 5,10,15,20-tetraphenyl-21H,23H-porphyrin vanadium(IV) oxide, 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphyrin, 29H,31H-phthalocyanine copper(II), phthalocyanine zinc(II), phthalocyanine titanium, phthalocyanine magnesium oxide, phthalocyanine lead, phthalocyanine copper(II), and 4,4',4'',4'''-tetraaza-29H,31H-phthalocyanine.

[0457] A preferred specific example of an oligothiophene derivative that can be used as a hole transport material is α-sexithiophene.

[0458] The molecular weight of these hole transport materials, except for the case of polymer compounds having the above-mentioned specific repeating units, is usually 5000 or less, preferably 3000 or less, more preferably 2000 or less, even more preferably 1700 or less, particularly preferably 1400 or less, and is usually 200 or more, preferably 400 or more, more preferably 600 or more. If the molecular weight of the hole transport material is too large, synthesis and purification are difficult, which is undesirable, whereas if the molecular weight is too small, heat resistance may be reduced, which is also undesirable.

[0459] The hole injection layer of the organic electroluminescent device of the present invention may contain any one of the above-mentioned hole transport materials alone or may contain two or more. When the hole injection layer contains two or more hole transport materials, the combination is arbitrary, but it is preferable to use one or more aromatic tertiary amine polymer compounds in combination with one or more other hole transport materials. The type of hole transport material to be used in combination with the above-mentioned polymer compounds is preferably an aromatic amine compound.

[0460] The content of the hole transport material in the hole injection layer of the organic electroluminescent device of the present invention is set to be within the range that satisfies the ratio with the electron accepting compound described above. When two or more kinds of compositions for charge transport film are used in combination, the total content of these is set to be within the above range.

[0461] [Charge-transporting ionic compounds] The hole injection layer of the organic electroluminescent device of the present invention preferably contains a charge transporting ionic compound in which the tetraarylborate ion and a cation radical of a hole transport material are ionically bonded to each other.

[0462] The hole injection layer of the organic electroluminescent device of the present invention particularly preferably contains a charge transporting ionic compound in which the tetraarylborate ion and the cation radical of the aromatic tertiary amine polymer compound are ionically bonded as a hole transporting material.

[0463] This charge transporting ionic compound can be obtained by any of the following methods. i) The first ionic compound and the hole transport material are mixed by dissolving or dispersing them in an organic solvent. ii) The first ionic compound and the hole transport material are dissolved or dispersed in an organic solvent, mixed, and then heated. iii) The composition obtained in i) or ii) above is wet-formed into a film, and the film is heated.

[0464] Since the first ionic compound is an electron-accepting compound, the hole transport material is oxidized to a cation radical by the first ionic compound in any of the above methods, resulting in the production of a charge-transporting ionic compound, which is an ionic compound having the tetraarylborate ion as a counter anion and the cation radical of the hole transport material as a counter cation.

[0465] The hole injection layer of the organic electroluminescent device of the present invention preferably contains a first ionic compound containing the tetraarylborate ion as a counter anion and a hole transport material, and more preferably contains a charge transporting ionic compound having the tetraarylborate ion as a counter anion and a cation radical of the hole transport material as a counter cation, from the viewpoint of charge transportability.

[0466] [Hole injection layer forming composition] The hole injection layer of the organic electroluminescent device of the present invention is preferably obtained by wet film formation of a composition for forming a hole injection layer.

[0467] The composition for forming a hole injection layer is preferably a composition obtained through a process of dissolving or dispersing the first ionic compound having a tetraarylborate ion structure and the hole transport material in an organic solvent.

[0468] From the viewpoint of obtaining a uniform film of the hole injection layer, the composition for forming the hole injection layer is preferably a solution in which the first ionic compound and the hole transport material are dissolved in an organic solvent.

[0469] Even if the composition for forming a hole injection layer obtained by the method i) does not contain the charge transporting ionic compound, it is sufficient that the charge transporting ionic compound can be obtained by the method ii) or iii), and even if the composition for forming a hole injection layer obtained by the method ii) does not contain the charge transporting ionic compound, it is sufficient that the charge transporting ionic compound can be obtained by the method iii).

[0470] The compounding ratio of the first ionic compound to the hole transport material for obtaining a composition for forming a hole injection layer is such that the amount of the first ionic compound is usually 0.1 parts by mass or more, preferably 1 part by mass or more, and usually 100 parts by mass or less, preferably 40 parts by mass or less, relative to 100 parts by mass of the hole transport material. If the content of the first ionic compound is above the lower limit, free carriers (cation radicals of the hole transport material) can be sufficiently generated, and hole transportability is improved, which is preferable, and if it is below the upper limit, sufficient charge transport ability can be ensured, which is preferable. When two or more types of the first ionic compound are used in combination, the total content of these is set to be within the above range. The same applies to the hole transport material.

[0471] (Organic solvent) The concentration of the organic solvent in the composition for forming a hole injection layer is usually 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more, and is usually 99.999% by mass or less, preferably 99.99% by mass or less, and even more preferably 99.9% by mass or less. When two or more organic solvents are used in combination, the total of these organic solvents should satisfy this range.

[0472] Examples of preferred organic solvents include ether-based solvents and ester-based solvents. Specifically, examples of ether-based solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); aromatic ethers such as 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, and 2,4-dimethylanisole. Examples of ester-based solvents include aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate. Any one of these may be used alone, or two or more may be used in any combination and ratio.

[0473] Examples of solvents that can be used other than the above-mentioned ether-based solvents and ester-based solvents include aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene, amide-based solvents such as N,N-dimethylformamide and N,N-dimethylacetamide, and dimethyl sulfoxide. Any one of these may be used alone, or two or more may be used in any combination and ratio. In addition, one or more of these solvents may be used in combination with one or more of the above-mentioned ether-based solvents and ester-based solvents. In particular, aromatic hydrocarbon-based solvents such as benzene, toluene, and xylene have a low ability to dissolve electron-accepting compounds and free carriers (cation radicals), so it is preferable to use them in combination with ether-based solvents and ester-based solvents.

[0474] Among these organic solvents, solvents having an aromatic hydrocarbon structure are more preferable.

[0475] (Film forming method) The hole injection layer can be formed by wet film formation using a composition for forming a hole injection layer. The wet film-forming method is the same as the method of forming a film by wet film-forming the composition for forming the light-emitting layer, but it is preferable to heat the film after coating and drying. The heating temperature is preferably 120° C. or higher, more preferably 150° C. or higher, and even more preferably 180° C. or higher, and is preferably 300° C. or lower, and more preferably 260° C. or lower.

[0476] The hole injection layer can be crosslinked by heating the film after coating and drying. At this time, the crosslinking reaction can occur in the following combinations.

[0477] Between the cross-linking groups of the hole transport material Crosslinking groups of hole transport materials and charge accepting compounds Between the cross-linking groups of electron-accepting compounds Crosslinking groups of hole transport materials and crosslinking groups of tetraarylborate ions in the present invention The crosslinking groups of the tetraarylborate ions in the present invention The crosslinking group of the electron-accepting compound and the crosslinking group of the tetraarylborate ion of the present invention

[0478] Furthermore, heating is preferable because it promotes the formation of a charge-transporting ionic compound, which is an ionic compound of a tetraarylborate ion, which is the counter anion of the first ionic compound, and a cation radical of a hole-transporting material.

[0479] <Structure of organic electroluminescent device> As one example of the structure of the organic electroluminescent element of the present invention, a schematic diagram (cross section) of an example of the structure of an organic electroluminescent element 8 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.

[0480] [substrate] The substrate 1 is a support for the organic electroluminescent element, and is usually made of a quartz or glass plate, a metal plate or metal foil, a plastic film or sheet, or the like. Of these, a glass plate or a plate made of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferred. The substrate is preferably made of a material with high gas barrier properties, since the organic electroluminescent element is less likely to deteriorate due to the outside air. For this reason, when a material with low gas barrier properties such as a synthetic resin substrate is used, it is preferable to provide a dense silicon oxide film or the like on at least one side of the substrate to increase the gas barrier properties.

[0481] [anode] The anode 2 has the function of injecting holes into the layers on the light-emitting layer 5 side.

[0482] The anode 2 is usually composed of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as indium and / or tin oxide; a metal halide such as copper iodide; carbon black, and a conductive polymer such as poly(3-methylthiophene), polypyrrole, or polyaniline.

[0483] The anode 2 is usually formed by a dry method such as sputtering or vacuum deposition. When forming the anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, fine conductive metal oxide particles, fine conductive polymer powder, etc., the anode can be formed by dispersing them in an appropriate binder resin solution and applying it onto a substrate. In the case of a conductive polymer, a thin film can be formed directly on the substrate by electrolytic polymerization, or the conductive polymer can be applied onto the substrate to form the anode (Appl. Phys. Lett., Vol. 60, p. 2711, 1992).

[0484] The anode 2 usually has a single-layer structure, but may have a laminated structure as appropriate. When the anode 2 has a laminated structure, a different conductive material may be laminated on the first anode layer.

[0485] The thickness of the anode 2 may be determined according to the required transparency and material. When particularly high transparency is required, a thickness that provides a visible light transmittance of 60% or more is preferable, and a thickness that provides a visible light transmittance of 80% or more is more preferable. The thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. On the other hand, when transparency is not required, the thickness of the anode 2 may be arbitrarily determined according to the required strength, and in this case, the anode 2 may have the same thickness as the substrate.

[0486] When another layer is formed on the surface of the anode 2, it is preferable to perform a treatment with ultraviolet light / ozone, oxygen plasma, argon plasma, or the like before the film formation to remove impurities on the anode 2 and to adjust the ionization potential to improve the hole injection property.

[0487] [Hole injection layer] The hole injection layer in the organic electroluminescent device of the present invention is as described above. Although the wet film formation method has been described above as a method for forming the hole injection layer, a vacuum deposition method may also be used.

[0488] [Formation of hole injection layer by vacuum deposition method] When the hole injection layer of the organic electroluminescent device of the present invention is formed by a vacuum deposition method, the first ionic compound is used as the material containing tetraarylborate ions, and a vapor-depositable low-molecular-weight hole transport material can be used as the hole transport material. As the vapor-depositable low-molecular-weight hole transport material, a hole transport material having a molecular weight of 1500 or less is preferable, a hole transport material having a molecular weight of 1000 or less is more preferable, a hole transport material having a molecular weight of 400 or more is preferable, and a hole transport material having a molecular weight of 600 or more is even more preferable. As the low-molecular-weight hole transport material, an aromatic amine compound is preferable, and an aromatic tertiary amine compound is even more preferable.

[0489] When forming the hole injection layer 3 by the vacuum deposition method, one or more of the constituent materials of the hole injection layer 3 are usually placed in a crucible installed in a vacuum chamber (when two or more materials are used, each is usually placed in a separate crucible), and the inside of the vacuum chamber is evacuated by a vacuum pump for 10 -4 The chamber is evacuated to about 10 Pa. The crucible is then heated (when two or more types of materials are used, each crucible is usually heated) to evaporate the materials in the crucible while controlling the amount of evaporation (when two or more types of materials are used, each material is usually evaporated while controlling the amount of evaporation independently), forming a hole injection layer on the anode on the substrate placed opposite the crucible. When two or more types of materials are used, a mixture of the materials can also be placed in the crucible and heated and evaporated to form a hole injection layer.

[0490] The degree of vacuum during deposition is not limited as long as it does not significantly impair the effects of the present invention. -6 Torr (0.13×10 -4 Pa) or above, 9.0×10 -6 Torr (12.0 × 10 -4 The deposition rate is not limited as long as it does not significantly impair the effects of the present invention, but is usually 0.1 Å / sec or more and 5.0 Å / sec or less. The deposition temperature during deposition is not limited as long as it does not significantly impair the effects of the present invention, but is preferably 10° C. or more and 50° C. or less.

[0491] [Hole transport layer] The hole transport layer 4 is a layer that transports holes from the anode 2 side to the light emitting layer 5 side. The hole transport layer 4 is not an essential layer in the organic electroluminescent device of the present invention, but it is preferable to form this layer in terms of enhancing the function of transporting holes from the anode 2 to the light emitting layer 5. When the hole transport layer 4 is formed, it is usually formed between the anode 2 and the light emitting layer 5. Furthermore, when the above-mentioned hole injection layer 3 is present, it is formed between the hole injection layer 3 and the light emitting layer 5.

[0492] The thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and on the other hand, is usually 300 nm or less, preferably 100 nm or less.

[0493] The hole transport layer 4 may be formed by a vacuum deposition method or a wet film formation method, but is preferably formed by a wet film formation method in terms of excellent film formability.

[0494] The hole transport layer 4 usually contains a hole transport compound.

[0495] Examples of hole transport compounds include aromatic diamines containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (JP Patent Publication No. 5-234681), and aromatic amine compounds having a starburst structure, such as 4,4',4''-tris(1-naphthylphenylamino)triphenylamine (J. Lumin., Vol. 72-74, 999). Preferred examples include aromatic amine compounds consisting of triphenylamine tetramers (Chem. Commun., p. 2175, 1996), spiro compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene (Synth. Metals, vol. 91, p. 209, 1997), and carbazole derivatives such as 4,4'-N,N'-dicarbazolebiphenyl. In addition, polyvinylcarbazole, polyvinyltriphenylamine (JP Patent Publication 7-53953 A), and polyarylene ether sulfones containing tetraphenylbenzidine (Polym. Adv. Tech., vol. 7, p. 33, 1996) may also be included.

[0496] [Formation of hole transport layer by wet film formation method] When forming a hole transport layer by a wet film formation method, the hole transport layer is usually formed using a composition for forming a hole transport layer instead of the composition for forming a hole injection layer, in the same manner as when the above-mentioned hole injection layer is formed by a wet film formation method.

[0497] When the hole transport layer is formed by a wet film formation method, the composition for forming the hole transport layer usually further contains a solvent. The solvent used in the composition for forming the hole transport layer may be the same as the solvent used in the composition for forming the hole injection layer described above.

[0498] The concentration of the hole transporting compound in the composition for forming a hole transport layer can be in the same range as the concentration of the hole transporting compound in the composition for forming a hole injection layer.

[0499] [Formation of hole transport layer by vacuum deposition method] When the hole transport layer is formed by the vacuum deposition method, it can be formed by using a composition for forming a hole transport layer instead of the composition for forming a hole injection layer in the same manner as when the hole injection layer is formed by the vacuum deposition method. The film formation conditions such as the degree of vacuum, deposition rate, and temperature during deposition can be the same as those during the vacuum deposition of the hole injection layer.

[0500] [Light-emitting layer] The light-emitting layer 5 is a layer that is excited by the recombination of holes injected from the anode 2 and electrons injected from the cathode 7 when an electric field is applied between a pair of electrodes, and thus emits light. The light-emitting layer 5 is a layer formed between the anode 2 and the cathode 7. When a hole injection layer is provided on the anode, the light-emitting layer is formed between the hole injection layer and the cathode. When a hole transport layer is provided on the anode, the light-emitting layer is formed between the hole transport layer and the cathode.

[0501] As described above, the light-emitting layer of the organic electroluminescent device of the present invention preferably contains a polycyclic heterocyclic compound represented by formula (1) and a host material.

[0502] The thickness of the light-emitting layer 5 is arbitrary as long as it does not significantly impair the effects of the present invention, but a thicker thickness is preferable in terms of preventing defects from occurring in the film, and a thinner thickness is preferable in terms of making it easier to achieve a low driving voltage. For this reason, the thickness is preferably 3 nm or more, more preferably 5 nm or more, and usually is preferably 200 nm or less, more preferably 100 nm or less.

[0503] The light-emitting layer 5 contains at least a material having light-emitting properties (light-emitting material), and preferably contains one or more host materials.

[0504] [Hole blocking layer] A hole blocking layer may be provided between the light emitting layer 5 and an electron injection layer described later. The hole blocking layer is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 7 side.

[0505] This hole blocking layer has the role of preventing holes migrating from the anode 2 from reaching the cathode 7, and the role of efficiently transporting electrons injected from the cathode 7 toward the light emitting layer 5. Required physical properties of the material constituting the hole blocking layer include high electron mobility and low hole mobility, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1).

[0506] Examples of materials for the hole blocking layer that satisfy these conditions include mixed ligand complexes such as bis(2-methyl-8-quinolinolato)(phenolato)aluminum and bis(2-methyl-8-quinolinolato)(triphenylsilanolate)aluminum; metal complexes such as bis(2-methyl-8-quinolinolato)aluminum-μ-oxo-bis-(2-methyl-8-quinolinolato)aluminum binuclear metal complex; styryl compounds such as distyrylbiphenyl derivatives (JP Patent Publication No. 11-242996); triazole derivatives such as 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (JP Patent Publication No. 7-41759); and phenanthroline derivatives such as bathocuproine (JP Patent Publication No. 10-79297). Furthermore, compounds having at least one pyridine ring substituted at the 2-, 4- and 6-positions, as described in International Publication No. 2005 / 022962, are also preferred as materials for the hole blocking layer.

[0507] There is no limitation on the method for forming the hole blocking layer, and it can be formed by a wet film forming method, a vapor deposition method, or other methods.

[0508] The thickness of the hole blocking layer is arbitrary as long as it does not significantly impair the effects of the present invention, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

[0509] [Electron transport layer] The electron transport layer 6 is provided between the light emitting layer 5 and the cathode 7 for the purpose of further improving the current efficiency of the device.

[0510] The electron transport layer 6 is made of a compound capable of efficiently transporting electrons injected from the cathode 7 between the electrodes to which an electric field is applied, toward the light emitting layer 5. The electron transporting compound used in the electron transport layer 6 is required to have a high efficiency of electron injection from the cathode 7, high electron mobility, and capable of efficiently transporting the injected electrons.

[0511] Specific examples of the electron transporting compound used in the electron transport layer include metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP-A-59-194393), metal complexes of 10-hydroxybenzo[h]quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (U.S. Pat. No. 5,645,948), quinoxaline compounds (JP-A-6-207169), phenanthroline derivatives (JP-A-5-331459), 2-tert-butyl-9,10-N,N'-dicyanoanthraquinone diimine, n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, and n-type zinc selenide.

[0512] The thickness of the electron transport layer 6 is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

[0513] The electron transport layer 6 is formed on the hole blocking layer by the wet film forming method or the vacuum deposition method in the same manner as described above. Usually, the vacuum deposition method is used.

[0514] [Electron injection layer] The electron injection layer may be provided in order to efficiently inject electrons injected from the cathode 7 into the electron transport layer 6 or the light emitting layer 5.

[0515] To efficiently inject electrons, the material forming the electron injection layer is preferably a metal with a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The thickness of the layer is usually preferably 0.1 nm or more and 5 nm or less.

[0516] Furthermore, it is also preferable to dope an organic electron transport material, typified by a nitrogen-containing heterocyclic compound such as bathophenanthroline or a metal complex such as an aluminum complex of 8-hydroxyquinoline, with an alkali metal such as sodium, potassium, cesium, lithium or rubidium (as described in JP-A-10-270171, JP-A-2002-100478, JP-A-2002-100482, etc.), since this improves the electron injection and transport properties and makes it possible to simultaneously achieve excellent film quality.

[0517] The thickness of the electron injection layer is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

[0518] The electron injection layer is formed by laminating it on the light-emitting layer 5 or the hole blocking layer or electron transport layer 6 thereon by a wet film formation method or a vacuum deposition method. The details of the wet film formation method are the same as those of the light-emitting layer described above.

[0519] In some cases, the hole blocking layer, the electron transporting layer and the electron injecting layer are combined into one layer by co-doping the electron transporting material with a lithium complex.

[0520] [cathode] The cathode 7 plays a role of injecting electrons into a layer on the light-emitting layer 5 side (such as an electron injection layer or a light-emitting layer).

[0521] The material of the cathode 7 can be the same as that of the anode 2, but in order to efficiently inject electrons, it is preferable to use a metal with a low work function, such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof. Specific examples include low-work-function alloy electrodes such as a magnesium-silver alloy, a magnesium-indium alloy, and an aluminum-lithium alloy.

[0522] From the viewpoint of the stability of the organic electroluminescence device, it is preferable to laminate a metal layer having a high work function and stability against the atmosphere on the cathode to protect the cathode made of a metal having a low work function. Examples of the metal to be laminated include aluminum, silver, copper, nickel, chromium, gold, platinum, etc.

[0523] The thickness of the cathode is usually the same as that of the anode.

[0524] [Other layers] The organic electroluminescent device of the present invention may further include other layers as long as the effects of the present invention are not significantly impaired. That is, the organic electroluminescent device of the present invention may include any of the above-mentioned layers between the anode and the cathode.

[0525] [Other element configurations] The organic electroluminescent device of the present invention may have a structure opposite to that described above, that is, for example, a cathode, an electron injection layer, an electron transport layer, a hole blocking layer, a light emitting layer, a hole transport layer, a hole injection layer, and an anode laminated on a substrate in this order.

[0526] When the organic electroluminescent element of the present invention is applied to an organic electroluminescent device, it may be used as a single organic electroluminescent element, or may be used in a configuration in which a plurality of organic electroluminescent elements are arranged in an array, or may be used in a configuration in which anodes and cathodes are arranged in an XY matrix.

[0527] <Organic EL display device> The organic EL display device (organic electroluminescence element display device) of the present invention is equipped with the organic electroluminescence element of the present invention. The type and structure of the organic EL display device of the present invention are not particularly limited, and the organic EL display device can be assembled by a conventional method using the organic electroluminescence element of the present invention.

[0528] For example, the organic EL display device of the present invention can be formed by a method such as that described in "Organic EL Display" (Ohmsha, published on August 20, 2004, by Tokito Shizuo, Adachi Chihaya, and Murata Hideyuki).

[0529] <Organic EL lighting> The organic EL lighting (organic electroluminescence element lighting) of the present invention includes the organic electroluminescence element of the present invention. The type and structure of the organic EL lighting of the present invention are not particularly limited, and it can be assembled according to a conventional method using the organic electroluminescence element of the present invention. EXAMPLES

[0530] [Example 1] An organic electroluminescent device was fabricated in the following manner. A 50 nm thick indium tin oxide (ITO) transparent conductive film (Geomatec, sputtered film) was deposited on a glass substrate and patterned into 2 mm wide stripes using standard photolithography and hydrochloric acid etching to form the anode. The substrate with the ITO pattern formed in this way was ultrasonically cleaned with a surfactant solution, rinsed with ultrapure water, ultrasonically cleaned with ultrapure water, and rinsed with ultrapure water, in that order, then dried with compressed air and finally cleaned with ultraviolet ozone.

[0531] As a composition for forming a hole injection layer, a solution was prepared by dissolving 3.0 mass% of a hole transporting polymer compound having a repeating structure of the following formula (P-1) and 0.6 mass% of an electron accepting compound (HI-1) in ethyl benzoate.

[0532] [ka]

[0533] [ka]

[0534] This solution was spin-coated onto the above substrate in the atmosphere and dried on a hot plate in the atmosphere at 240° C. for 30 minutes to form a uniform thin film with a thickness of 40 nm, which was used as a hole injection layer.

[0535] Next, 100 parts by mass of a charge transporting polymer compound having the following structural formula (HT-1) was dissolved in cyclohexylbenzene to prepare a 3.0% by mass solution.

[0536] This solution was spin-coated in a nitrogen glove box onto the substrate on which the hole injection layer had been formed, and then dried on a hot plate in the nitrogen glove box at 230°C for 30 minutes to form a uniform thin film with a thickness of 40 nm, which served as a hole transport layer.

[0537] [ka]

[0538] Subsequently, 97 parts by mass of the following structural formula (H-1) and 3 parts by mass of (D-1) were weighed as materials for the light-emitting layer, and dissolved in cyclohexylbenzene to prepare a 4.2% by mass solution.

[0539] [ka]

[0540] This solution was spin-coated in a nitrogen glove box onto the substrate on which the hole transport layer had been formed, and dried on a hot plate in the nitrogen glove box at 120°C for 20 minutes to form a uniform thin film with a thickness of 40 nm, which was used as the light-emitting layer.

[0541] The substrate on which the light-emitting layer had been formed was placed in a vacuum deposition apparatus, and the inside of the apparatus was heated to 2 × 10 -4 The pressure was evacuated until the pressure was below 1 Pa.

[0542] Next, the following structural formula (ET-1) and 8-hydroxyquinolinolatolithium were co-deposited on the light-emitting layer in a thickness ratio of 2:3 by vacuum deposition to form a hole blocking layer with a thickness of 30 nm.

[0543] [ka]

[0544] Next, a 2 mm wide striped shadow mask was attached to the substrate as a mask for cathode deposition so as to be perpendicular to the ITO stripes of the anode, and aluminum was heated in a molybdenum boat to form an aluminum layer with a thickness of 80 nm to form a cathode. In this manner, an organic electroluminescent device having a light-emitting area of ​​2 mm x 2 mm was obtained.

[0545] [Comparative Example 1] An organic electroluminescence device was produced in the same manner as in Example 1, except that 0.3% by mass of tetracyanoquinodimethane was used to prepare a composition for forming a hole injection layer instead of 0.6% by mass of the electron accepting compound (HI-1).

[0546] [Evaluation of organic electroluminescent device] The organic electroluminescent devices obtained in Example 1 and Comparative Example 1 were subjected to a current of 10 mA / cm 2 The voltage (V) was measured when a current density of 20 mA / cm was applied to the organic electroluminescent device. 2 The time required for the luminance of the organic electroluminescent device to decrease to 90% of the initial luminance when a current was continuously applied at a current density of 1000 Hz was measured as the lifetime (hr).

[0547] Table 1 shows the voltage difference (V) obtained by subtracting the voltage of Comparative Example 1 from the voltage of Example 1, and the relative lifespan of Example 1 when the lifespan of Comparative Example 1 is taken as 1.

[0548] [Table 1]

[0549] From the results in Table 1, it was found that the organic electroluminescent device of the present invention has a low driving voltage and a long driving life.

[0550] [Example 2] An organic electroluminescence device was produced in the same manner as in Example 1, except that the electron-accepting compound (HI-2) was used in place of the electron-accepting compound (HI-1) to form a hole-injection layer.

[0551] [ka]

[0552] [ka]

[0553] [Evaluation of organic electroluminescent device] The organic electroluminescent devices obtained in Examples 1 and 2 were subjected to a current of 10 mA / cm 2 The voltage (V), the current luminous efficiency (cd / A) and the external quantum efficiency (%) were measured when a current was applied at a current density of 20 mA / cm. 2 The time required for the luminance of the organic electroluminescent device to decrease to 95% of the initial luminance when a current was continuously applied at a current density of 1000 Hz was measured as the lifetime (hr).

[0554] Table 2 shows the voltage difference (V) obtained by subtracting the voltage of Example 1 from the voltage of Example 2, the relative current luminous efficiency of Example 2 when the current luminous efficiency of Example 1 is set to 1, the relative external quantum efficiency (EQE) of Example 2 when the EQE of Example 1 is set to 1, and the relative lifetime of Example 2 when the lifetime of Example 1 is set to 1.

[0555] [Table 2]

[0556] The results in Table 2 show that the hole injection layer containing a crosslinked product of an electron accepting compound having a crosslinking group reduces the driving voltage, increases the luminous efficiency, and extends the driving life.

[0557] [Example 3] The procedure was the same as in Example 1 up to the formation of the hole injection layer. Next, a hole transport layer was formed in the same manner as in Example 1, except that a compound represented by the following formula (HT-2) was used as the material for the hole transport layer instead of the compound represented by the formula (HT-1).

[0558] Next, as materials for the light-emitting layer, 22.5 parts by mass of a compound represented by the following formula (H-2), 22.5 parts by mass of a compound represented by the following formula (H-3), 15.0 parts by mass of a compound represented by the following formula (H-4), and 3.0 parts by mass of a compound represented by the following formula (D-2) were weighed out and dissolved in cyclohexylbenzene to prepare a 4.2% by mass solution. An light-emitting layer was formed in the same manner as in Example 1, and the subsequent steps were also performed in the same manner as in Example 1 to produce an organic electroluminescent device.

[0559] [ka]

[0560] [ka]

[0561] [ka]

[0562] [Example 4] An organic electroluminescent device was prepared in the same manner as in Example 3, except that the electron accepting compound (HI-3) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0563] [ka]

[0564] [Example 5] An organic electroluminescent device was prepared in the same manner as in Example 3, except that the electron accepting compound (HI-2) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0565] [Example 6] An organic electroluminescent device was prepared in the same manner as in Example 5, except that the compound represented by the formula (HT-1) was used as the material for the hole transport layer instead of the compound represented by the formula (HT-2), and the compound represented by the following formula (D-3) was used as the material for the light emitting layer instead of the compound represented by the formula (D-2).

[0566] [ka]

[0567] [Comparative Example 2] An organic electroluminescent device was prepared in the same manner as in Example 3, except that the electron accepting compound (HI-C1) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0568] [ka]

[0569] [Evaluation of organic electroluminescent device] The organic electroluminescent devices obtained in Examples 3 to 6 and Comparative Example 2 were subjected to a current of 20 mA / cm 2 The time it took for the luminance of the organic electroluminescent device to decrease to 95% of the initial luminance when a current was continuously applied at a current density of 10 mA / cm2 was measured as the life (hr). 2 The voltage (V), current luminous efficiency (cd / A), and external quantum efficiency (%) were measured when a current was applied at a current density of 1000 V.

[0570] Table 3 shows the relative lifespan of each example when the lifespan of Comparative Example 2 is taken as 1. Table 4 shows the relative current luminous efficiency of Examples 4 to 6 when the current luminous efficiency of Example 3 is taken as 1, and the relative external quantum efficiency (EQE) of Examples 4 to 6 when the EQE of Example 3 is taken as 1.

[0571] [Table 3]

[0572] The results in Table 3 show that the organic electroluminescent element having the hole injection layer used in the present invention has a long operating life, and furthermore, the operating life is particularly long when the hole injection layer contains a crosslinked product of an electron accepting compound having a crosslinking group.

[0573] [Table 4]

[0574] The results in Table 4 show that the luminous efficiency was particularly high in Examples 5 and 6, in which the hole injection layer had a crosslinked product of an electron accepting compound having a crosslinking group.

[0575] [Advantages over conventional technologies] Next, organic electroluminescence devices having the electron-accepting compounds and light-emitting layers shown in Table 5 were fabricated, and the superiority of the effects over the case where the light-emitting layer was a phosphorescent light-emitting layer of the prior art was confirmed.

[0576] [Table 5]

[0577] [Example 7] The procedure was the same as in Example 3 up to the formation of the hole transport layer. After the formation of the light-emitting layer, the organic electroluminescence device was produced in the same manner as in Example 1.

[0578] [Example 8] An organic electroluminescent device was prepared in the same manner as in Example 7, except that the electron accepting compound (HI-3) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0579] [Comparative Example 3] An organic electroluminescent device was prepared in the same manner as in Example 7, except that the electron accepting compound (HI-C1) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0580] [Comparative Example 4] An organic electroluminescent device was produced in the same manner as in Example 7, except that 22.5 parts by mass of the compound represented by formula (H-2) above, 22.5 parts by mass of the compound represented by formula (H-3) above, 15.0 parts by mass of the compound represented by formula (H-5) below, and 18.0 parts by mass of the compound represented by formula (D-4) below were weighed out as materials for the light-emitting layer and dissolved in cyclohexylbenzene to prepare a 4.2% by mass solution.

[0581] [ka]

[0582] [Comparative Example 5] An organic electroluminescent device was prepared in the same manner as in Comparative Example 4, except that the electron accepting compound (HI-3) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0583] [Comparative Example 6] An organic electroluminescent device was prepared in the same manner as in Comparative Example 4, except that the electron accepting compound (HI-C1) was used instead of the electron accepting compound (HI-1) to prepare a composition for forming a hole injection layer.

[0584] [Evaluation of organic electroluminescent device] The organic electroluminescence devices obtained in Examples 7 and 8 and Comparative Examples 3 to 6 were subjected to a current of 10 mA / cm 2The voltage (V) and the luminous efficiency (current luminous efficiency (cd / A) and external quantum efficiency (EQE) (%) were measured when a current was applied at a current density of 20 mA / cm. 2 The organic electroluminescent devices obtained in Comparative Examples 4 to 6 were continuously energized at a current density of 15 mA / cm 2 The time until the luminance of the organic electroluminescent device decreased to 85% of the initial luminance was measured as the lifetime (hr).

[0585] As the effect of reducing the voltage in the organic electroluminescence device of the present invention, the voltage difference (V) of "Voltage of Example 7 or 8" minus "Voltage of Comparative Example 3" was calculated and shown in Table 6. As the effect of the current luminous efficiency in the organic electroluminescent device of the present invention, "current luminous efficiency of Example 7 or 8" / "current luminous efficiency of Comparative Example 3" was calculated as a relative current luminous efficiency, and is shown in Table 6. As the EQE effect in the organic electroluminescence device of the present invention, "EQE of Example 7 or 8" / "EQE of Comparative Example 3" was calculated as relative EQE and shown in Table 6. As an effect of extending the lifespan of the organic electroluminescence device of the present invention, the relative lifespan was calculated by dividing the lifespan of Example 7 or 8 by the lifespan of Comparative Example 3, and the results are shown in Table 6.

[0586] Similarly, for the conventional organic electroluminescent device, the relative voltage was calculated by subtracting the voltage of Comparative Example 6 from the voltage of Comparative Example 4 or 5, and the result is shown in Table 6. As the relative current luminous efficiency, “current luminous efficiency of Comparative Example 4 or Comparative Example 5” / “current luminous efficiency of Comparative Example 6” was calculated and shown in Table 6. As the relative EQE, “EQE of Comparative Example 4 or Comparative Example 5” / “EQE of Comparative Example 6” was calculated and shown in Table 6. The relative life span was calculated as "life span in Comparative Example 4 or Comparative Example 5" / "life span in Comparative Example 6" and shown in Table 6.

[0587] [Table 6]

[0588] As can be seen from Table 6, when the light-emitting layer contains the polycyclic heterocyclic compound of the formula (1), the organic electroluminescent device having a hole-injection layer containing the electron-accepting compound used in the present invention has a low voltage, a high current luminous efficiency, a high EQE, and a long lifetime; however, this is not necessarily the case or the degree of this is low in the case of an organic electroluminescent device having a light-emitting layer that is a conventional phosphorescent light-emitting layer, and the unique effect of the present invention can be confirmed.

[0589] Although the present invention has been described in detail and with reference to specific embodiments, it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese patent applications filed on December 23, 2020 (Patent Application No. 2020-214273) and December 23, 2020 (Patent Application No. 2020-214274), the contents of which are incorporated herein by reference. [Explanation of symbols]

[0590] 1 Board 2 Anode 3. Hole injection layer 4. Hole transport layer 5. Light-emitting layer 6 Electron transport layer 7 Cathode 8. Organic electroluminescent device

Claims

1. An organic electroluminescent device having an anode, a cathode, a light-emitting layer, and a hole injection layer, the light-emitting layer is provided between the anode and the cathode, the hole injection layer is provided between the anode and the light emitting layer, The light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1): The organic electroluminescent device, wherein the hole injection layer contains a tetraarylborate ion. 【Chemistry 1】 (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, N-R or S; R represents an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

2. The organic electroluminescent device according to claim 1 , wherein the tetraarylborate ion is represented by the following formula (2): 【Chemistry 2】 (In formula (2), Ar １ , Ar ２ , Ar ３ and Ar ４ each independently represents a monovalent group formed by linking a plurality of structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, or an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, Ar １ , Ar ２ , Ar ３ and Ar ４ At least one of has a fluorine atom or a fluorine-substituted alkyl group as a substituent.

3. Ar in the formula (2) １ , Ar ２ , Ar ３ and Ar ４ The organic electroluminescent device according to claim 2 , wherein at least one of the above is a group represented by the following formula (3): 【Chemistry 3】 (In formula (3), R １ each independently represents a monovalent group having a plurality of linked structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, a fluorine-substituted alkyl group, a substituent, or a crosslinking group, F ４ represents four fluorine atoms are substituted, F （５－ｍ） each independently represents substitution with 5-m fluorine atoms, Each k independently represents an integer of 0 to 5. Each m independently represents an integer of 0 to 5.

4. In the formula (2), Ar １ , Ar ２ , Ar ３ and Ar ４ The organic electroluminescent element according to claim 2 , wherein at least one of the following has the crosslinking group:

5. The organic electroluminescent device according to claim 4, wherein the crosslinking group is represented by any one of the following formulas (X1) to (X18): 【Chemistry 4】 In formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) １１０ each independently represents an alkyl group.

6. 6. The organic electroluminescent device according to claim 5, wherein the crosslinking group is represented by any one of formulas (X1) to (X3).

7. 7. The organic electroluminescent device according to claim 1, wherein the polycyclic heterocyclic compound represented by formula (1) is represented by the following formula (21): 【Chemistry 5】 (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d and ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium.

8. 7. The organic electroluminescent device according to claim 1, wherein the polycyclic heterocyclic compound represented by formula (1) is represented by the following formula (71): 【Chemistry 6】 (In formula (71), A １ ~A ７ each independently represents a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron-accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron-accepting substituent, a nitro group, or a cyano group, R ７１ ~R ７８ each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.)

9. An organic electroluminescent device having an anode, a cathode, a light-emitting layer, and a hole injection layer, the light-emitting layer is provided between the anode and the cathode, the hole injection layer is provided between the anode and the light emitting layer, The light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1): The hole injection layer of the organic electroluminescent device contains a crosslinked product of an electron accepting compound having a crosslinking group. 【Chemistry 7】 (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, N-R or S; R represents an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

10. The organic electroluminescent device according to claim 9, wherein the crosslinking group is represented by any one of the following formulas (X1) to (X18): 【Chemistry 8】 In formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) １１０ each independently represents an alkyl group.

11. The organic electroluminescent device according to claim 10, wherein the crosslinking group is represented by any one of the formulas (X1) to (X3).

12. The organic electroluminescent device according to any one of claims 9 to 11, wherein the polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): 【Chemistry 9】 (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d and ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium.

13. The organic electroluminescent device according to any one of claims 9 to 11, wherein the polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): 【Chemistry 10】 (In formula (71), A １ ~A ７ each independently represents a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron-accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron-accepting substituent, a nitro group, or a cyano group, R ７１ ~R ７８ each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.)

14. An organic EL display device or organic EL lighting comprising the organic electroluminescent device according to any one of claims 1 to 13.

15. A method for manufacturing an organic electroluminescent device having an anode, a hole injection layer, a light emitting layer, and a cathode on a substrate in this order, comprising the steps of: The method for producing the organic electroluminescent device includes forming the hole injection layer by a wet film formation method using a composition for forming the hole injection layer; forming the light-emitting layer by a wet film-forming method using a composition for forming a light-emitting layer; The composition for forming a hole injection layer contains tetraarylborate ions and an organic solvent, The composition for forming a light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1) and an organic solvent: A method for manufacturing an organic electroluminescent device. 【Chemistry 11】 (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, N-R or S; R represents an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

16. 16. The method for producing an organic electroluminescence device according to claim 15, wherein the composition for forming a hole injection layer is a composition obtained through a process of dissolving or dispersing an electron accepting ionic compound having a tetraarylborate ion structure and a hole transport material in an organic solvent.

17. The method for producing an organic electroluminescence device according to claim 15 or 16, wherein the tetraarylborate ion is represented by the following formula (2): 【Chemistry 12】 (In formula (2), Ar １ , Ar ２ , Ar ３ and Ar ４ each independently represents a monovalent group formed by linking a plurality of structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, or an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, Ar １ , Ar ２ , Ar ３ and Ar ４ At least one of has a fluorine atom or a fluorine-substituted alkyl group as a substituent.

18. Ar in the formula (2) １ , Ar ２ , Ar ３ and Ar ４ The method for producing an organic electroluminescence element according to claim 17 , wherein at least one of the above is a group represented by the following formula (3): 【Chemistry 13】 (In formula (3), R １ each independently represents a monovalent group having a plurality of linked structures selected from an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, an aromatic hydrocarbon ring group which may have a substituent and / or a crosslinking group, and an aromatic heterocyclic group which may have a substituent and / or a crosslinking group, a fluorine-substituted alkyl group, a substituent, or a crosslinking group, F ４ represents four fluorine atoms are substituted, F （５－ｍ） each independently represents substitution with 5-m fluorine atoms, Each k independently represents an integer of 0 to 5. Each m independently represents an integer of 0 to 5.

19. In the formula (2), Ar １ , Ar ２ , Ar ３ and Ar ４ The method for producing an organic electroluminescence element according to claim 17 or 18, wherein at least one of the following has the crosslinking group.

20. The method for producing an organic electroluminescent device according to claim 19, wherein the crosslinking group is represented by any one of the following formulas (X1) to (X18): 【Chemistry 14】 In formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) １１０ each independently represents an alkyl group.

21. The method for producing an organic electroluminescent device according to claim 20, wherein the crosslinking group is represented by any one of formulas (X1) to (X3).

22. The method for producing an organic electroluminescence device according to any one of claims 15 to 21, wherein the polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): 【Chemistry 15】 (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d and ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium.

23. The method for producing an organic electroluminescence device according to any one of claims 15 to 22, wherein the polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): 【Chemistry 16】 (In formula (71), A １ ~A ７ each independently represents a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron-accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron-accepting substituent, a nitro group, or a cyano group, R ７１ ~R ７８ each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.)

24. A method for manufacturing an organic electroluminescent device having an anode, a hole injection layer, a light emitting layer, and a cathode on a substrate in this order, comprising the steps of: The method for producing the organic electroluminescent device includes forming the hole injection layer by a wet film formation method using a composition for forming the hole injection layer; forming the light-emitting layer by a wet film-forming method using a composition for forming a light-emitting layer; The composition for forming a hole injection layer includes an electron accepting compound having a crosslinking group and an organic solvent, The composition for forming a light-emitting layer contains a polycyclic heterocyclic compound represented by the following formula (1) and an organic solvent: A method for manufacturing an organic electroluminescent device. 【Chemistry 17】 (In formula (1), ring a, ring b, and ring c each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Y is O, N-R or S; R represents an aromatic hydrocarbon ring group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or an alkyl group which may have a substituent, The R is a ring selected from the group consisting of the ring a, the ring b, and the ring c, and is selected from the group consisting of a carbon atom adjacent to the atom bonded to the Y, and -O-, -S-, -C(-R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, The adjacent carbon atom is not a carbon atom constituting the central fused two-ring structure containing B and Y in formula (1). At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (1) may be substituted with a halogen atom or deuterium.

25. The method for producing an organic electroluminescent device according to claim 24, wherein the crosslinking group is represented by any one of the following formulas (X1) to (X18): 【Chemistry 18】 In formulae (X1) to (X4), the benzene ring and the naphthalene ring may have a substituent. In addition, the substituents may be bonded to each other to form a ring. R in formula (X4), formula (X5), formula (X6) and formula (X10) １１０ each independently represents an alkyl group.

26. The method for producing an organic electroluminescent device according to claim 25, wherein the crosslinking group is represented by any one of the formulas (X1) to (X3).

27. The method for producing an organic electroluminescence device according to any one of claims 24 to 26, wherein the polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (21): 【Chemistry 19】 (In formula (21), Ring a, ring b and ring c are the same as those in formula (1), Ring d and ring e each have a structure in which two saturated hydrocarbon rings each containing B and two Ys are condensed together, ring f and ring g are the same as ring a, ring b, or ring c, and each independently represents an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocycle which may have a substituent; Ring f is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and b is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, Ring g is a ring in which the carbon atom adjacent to the atom bonded to N in at least one of rings a and c is bonded to —O—, —S—, —C(—R ａ ) ２ - or may be linked by a single bond, The R ａ is a hydrogen atom or an alkyl group, However, the adjacent carbon atom is not a carbon atom constituting ring d and ring e containing B and N, At least one hydrogen atom in the polycyclic heterocyclic compound represented by formula (21) may be substituted with a halogen atom or deuterium.

28. The method for producing an organic electroluminescence device according to any one of claims 24 to 27, wherein the polycyclic heterocyclic compound represented by the formula (1) is represented by the following formula (71): 【Chemistry 20】 (In formula (71), A １ ~A ７ each independently represents a hydrogen atom, a fluorine atom, an alkyl group which may have a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, or an aromatic hydrocarbon group or aromatic heterocyclic group which has, as a substituent, a heteroaryl group which is an electron accepting substituent, a nitro group, or a cyano group, R ７１ ~R ７８ each independently represents a hydrogen atom, an optionally substituted alkyl group, an optionally substituted aromatic hydrocarbon group, an optionally substituted aromatic heterocyclic group, an electron-donating substituent, or a combination thereof, The dotted line represents a single bond or no bond.)

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