Organic electroluminescent element

Abstract

[Problem] To provide an organic electroluminescent element including, in a light-emitting layer, an azafenylene derivative that exhibits a short delayed-fluorescence lifetime, a high emission-quantum yield, and high stability. [Solution] The aforementioned problem is solved by an organic electroluminescent element including, in a light-emitting layer, an azafenylene derivative represented by formula (I). The azafenylene derivative represented by formula (I) contains 1-3 carbazole-based substituents, and the basic skeleton of the azafenylene derivative is preferably heptadine. The energy difference ΔEST obtained by subtracting the energy level ET1 of the lowest triplet excited state from the energy level ES1 in the lowest singlet excited state is −0.20 eV ≤ ΔEST < 0 eV.

Description

Organic electroluminescent device

[0001] The present invention relates to an organic electroluminescent device containing a novel azaphenalene derivative (particularly a heptazine derivative).

[0002] WO / 2021 / 256446 describes an organic light-emitting device containing a heptazine derivative as a host compound. Japanese Patent Publication No. 6095643 describes a light-emitting material made of a heptazine derivative. CN Publication No. 106883240 describes a light-emitting device having a dicarbazole heptazine derivative (Example I-I).

[0003] Generally, the state with the largest spin multiplicity in the same electron configuration exhibits the lowest energy (Hund's rule). In other words, based on Hund's rule, the triplet state is generally more stable than the singlet state. Also, considering the exchange interaction, which is a quantum mechanical effect, the energy of the singlet state (E Ｓ１ ) and triplet state energy (E Ｔ１ ) are represented by the following formulas (1) and (2), respectively. Ｓ１ =Δε-J+K...Formula (1) E Ｔ１ =Δε−J−K Formula (2) Here, Δε represents the HOMO-LUMO gap (energy difference), J represents the Coulomb interaction, and K represents the exchange interaction.

[0004] The energy difference between the singlet and triplet states, ΔE ＳＴ is calculated as follows: ＳＴ = E Ｓ１ -E Ｔ１ = 2K (> 0) ... Equation (3) Then, ΔE ＳＴ is generally a positive value. However, when various electronic excited configurations are considered based on the Pauli exclusion principle, the energy of the singlet state may be stabilized by configuration interaction. When the configuration interaction exceeds the exchange interaction, ΔE ＳＴ The value of is negative.

[0005] WO / 2021 / 256446 pamphlet describes negative ΔE ＳＴ As a molecule exhibiting this property, a fluorescent heptazine derivative, HzTFEX２ It has been reported that this molecule has a very short delayed fluorescence lifetime of 217 ns. In addition, the fluorescence lifetime of this molecule shortens as the temperature decreases, and the RISC rate is faster than the ISC rate. These properties are different from those of conventional molecules that exhibit TADF. These unique properties are due to the HzTFEX ２ It was demonstrated that this is due to the energy inversion of the excited singlet and triplet states. ＳＴ Because the value of is negative, excited triplets that normally do not emit light can be rapidly converted to singlets and used to emit light. This makes it possible, in principle, to create organic electroluminescent devices with high brightness, efficiency, and durability. However, in order to demonstrate this principle, it was necessary to achieve both the charge injection properties of a semiconductor and the highly efficient light-emitting function.

[0006] In fact, this heptadine derivative (HzTFEX ２ ) may form an exciplex with the surrounding substances (e.g., carbazole derivatives) contained in the organic electroluminescent device, impairing the light-emitting properties. The excited state formed between two molecules, an electron-donating molecule and an electron-accepting molecule, is called an exciplex state. A negative ΔE ＳＴ Molecular HzTFEX ２ In the thin film using mCBP as the host molecule and HzTFEX as the guest molecule, ２ The exciplex emission was due to the transition from the LUMO of mCBP to the HOMO of the donor mCBP. ２ The HzTFEX ２ This is because the intermolecular HOMO-LUMO gap between the LUMO of mCBP and the HOMO of mCBP is smaller. Due to this exciplex emission, the PL spectrum exhibited a longer wavelength and broader peak than the toluene solution, which showed emission from heptazine. Thus, organic light-emitting devices containing the heptazine derivatives described in the above literature as host compounds could not be easily realized.

[0007] WO / 2021 / 256446 Pamphlet Patent No. 6095643 Publication CN 106883240 Publication

[0008] An object of the present invention is to provide an organic electroluminescent device containing an azaphenalene derivative in an emitting layer, which exhibits a short delayed fluorescence lifetime, a high luminescence quantum yield, and high stability.

[0009] The present invention is based on findings from examples, and the first invention relates to an organic electroluminescent device containing an azaphenalene derivative represented by formula (I) in a light-emitting layer.

[0010] In formula (I), X １ ~X ７ may be the same or different and represent a carbon atom or a nitrogen atom; X １ ~X ７ At least one of the groups is a nitrogen atom.

[0011] R １ ~R ３ may be the same or different and represent a group represented by formula (II), formula (III) or formula (VI).

[0012] In formula (II), * represents a linking moiety. ２１ is a C which may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ２２ and R ２３ may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－１０C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ２２ represents an integer of 0 to 3. ２３ represents an integer of 0 to 4. １１ ~X １７ may be the same or different and represent a carbon atom or a nitrogen atom.

[0013] In formula (III), * represents a linking moiety. ３１ and R ３２ may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ３１ represents an integer of 0 to 4. ３２ represents an integer of 0 to 4. ２１ ~X ２８ may be the same or different and represent a carbon atom or a nitrogen atom.

[0014] R ３１ and R ３２ may be a group represented by formula (III). ３１ and R ３２ may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－６ Preferably, it is an alkyl group, and m ３１ represents an integer of 0 to 4, and m ３２ represents an integer of 0 to 4, and X ２１ ~X ２８ may be the same or different and represent a carbon atom or a nitrogen atom.

[0015] In formula (IV), * represents a linking moiety. ４１ is a C which may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ４１ represents an integer of 0 to 5.

[0016] R ４１ is -Si(R ４２ ) m ４２ A silyl group (R ４２ may be the same or different, and are a hydrogen atom, C １－１０ Alkyl group or C ６－１０ represents an aryl group, m ４２ represents an integer of 1 to 3.) or two adjacent R ４１are taken together to form a five- or six-membered ring which may have a substituent, or two adjacent R ４１ may be taken together to form a bicyclic group containing a five- or six-membered ring, which may have a substituent.

[0017] Group A is a halogen atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an amino group; １ -C ６ Alkyl group; C ２ -C ６ Alkenyl group; C ２ -C ６ Alkynyl group; C １ -C ６ Alkoxy group; C １ -C ６ Alkylthio group; C ３ -C ７ Alicyclic hydrocarbon group; C ７ -C １６ Aralkyl group; Carbamoyl group; C ６ -C １０ aryl groups; and 5- to 7-membered aromatic heterocyclic groups.

[0018] As shown in the examples, the present invention can provide an organic electroluminescent device containing an azaphenalene derivative in an emitting layer, which exhibits a short delayed fluorescence lifetime, a high luminescence quantum yield, and high stability.

[0019] Figure 1 shows the HzTBPCz ３ 2 is a graph in place of a drawing showing the UV-Vis absorption spectrum and PL spectrum of HzTBPCz. ３ 3 shows a graph instead of a drawing showing the PL intensity (arbitrary units) of HzTBPCz. ３ 4 is a graph showing the PL spectrum of a HzTBPCz thin film. ３: a graph substituted for a drawing showing the PL intensity (arbitrary units) of the mCBP thin film. FIG. 5 is a graph substituted for a drawing showing the EL spectrum of the organic light-emitting device obtained in Example 1. FIG. 6 is a graph substituted for a drawing showing the current density-voltage-luminance characteristics of the organic light-emitting device obtained in Example 1. FIG. 7 is a graph substituted for a drawing showing the external quantum efficiency-luminance characteristics of the organic light-emitting device obtained in Example 1. FIG. 8 is a graph substituted for a drawing showing the current efficiency-luminance-power efficiency characteristics of the organic light-emitting device obtained in Example 1. FIG. 9 is a graph substituted for a drawing showing the HzCzM ２ , HzCzMa ２ , HzMCzM ２ , and HzMCzMa ２ 10 is a graph in place of a drawing showing the UV-vis absorption spectrum of HzCzA. ２ , HzMeCzA ２ , HzMeCzMp ２ , HzBCzM ２ and HztBuCzM ２ 11 is a graph in place of a drawing showing the UV-vis absorption spectrum of HzCzM ２ , HzCzMa ２ , HzMCzM ２ , and HzMCzMa ２ 12 is a graph instead of a drawing showing the PL spectrum of HzCzA. ２ , HzMeCzA ２ , HzMeCzMp ２ , HzBCzM ２ and HztBuCzM ２ 13 is a graph instead of a drawing showing the PL spectrum of HzCzMeA. ２ 14 is a graph instead of a drawing showing the PL spectrum of HzCzM ２ , HzCzMa ２ , HzMCzM ２ , and HzMCzMa ２ 15 is a graph in place of a drawing showing the room temperature transient PL decay of HzCzA. ２ , HzMeCzA ２ , HzMeCzMp ２ , HzBCzM ２ and HztBuCzM２ 16 is a graph in place of a drawing showing the room temperature transient PL decay of HzCzMeA. ２ 17 is a graph in place of a drawing showing the room temperature transient PL decay of HzCzM ２ 18 is a graph instead of a drawing showing fitting analysis of HzCzMa ２ 19 is a graph instead of a drawing showing fitting analysis of HzMCzMa ２ 20 is a graph instead of a drawing showing fitting analysis of HzCzA. ２ 21 is a graph instead of a drawing showing fitting analysis of HztBuCzM ２ FIG. 22 is a graph replacing a drawing showing an organic EL spectrum. The horizontal axis indicates wavelength, and the vertical axis indicates organic EL intensity (arbitrary units). FIG. 23 is a graph replacing a drawing showing current density-voltage-luminance characteristics. The horizontal axis indicates voltage. The vertical axis indicates current density and luminance. FIG. 24 is a graph replacing a drawing showing external quantum efficiency-luminance characteristics. The vertical axis indicates external quantum efficiency. The horizontal axis indicates luminance.

[0020] The following describes embodiments of the present invention. The present invention is not limited to the embodiments described below, and also includes appropriate modifications of the embodiments described below within the scope obvious to those skilled in the art.

[0021] This invention is based on findings from examples. The first invention relates to an organic electroluminescent device containing an azaphenalene derivative represented by formula (I) in an emitting layer. The azaphenalene derivative also functions as a luminescent material. This specification also discloses the azaphenalene derivative represented by formula (I) as a luminescent material, and a luminescent material containing the azaphenalene derivative represented by formula (I).

[0022] Organic Electroluminescent Devices Organic electroluminescent devices are light-emitting devices, also known as organic electroluminescent devices, organic electroluminescent devices, and OELDs. Organic electroluminescent devices are well known, as described in numerous documents, such as Japanese Patent No. 7388658 and Japanese Patent No. 6927497. The basic principle of organic electroluminescent devices is that when an electric field is applied between electrodes, electrons are injected from the cathode and holes are injected from the anode, and when these are recombined in the light-emitting layer, light is emitted as energy. The organic electroluminescent device of this invention may include an azaphenalene derivative represented by formula (I) in the light-emitting layer, and may also include known elements for organic electroluminescent devices as appropriate. Furthermore, when manufacturing an organic electroluminescent device, the organic electroluminescent device may be manufactured by appropriately employing a known method in addition to including an azaphenalene derivative represented by formula (I) in the light-emitting layer. The organic electroluminescent device includes an light-emitting layer and a pair of opposing electrodes sandwiching the light-emitting layer.

[0023] Configuration of Organic Electroluminescent Device An example configuration of an organic electroluminescent device includes, in this order, a substrate, an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode. Another example configuration of an organic electroluminescent device may include, in this order, a substrate, a cathode, an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, a hole injection layer, and an anode. The organic electroluminescent device may further include, for example, one or more of a sealing layer, a hole injection transport layer, an electron blocking layer, and a hole blocking layer.

[0024] The substrate serves as a support for the organic electroluminescent device, and examples of the substrate include quartz, a glass plate, a metal plate, a metal foil, a plastic film, and a sheet.

[0025] The anode serves to inject holes into the hole transport layer. Examples of materials for the anode include metals such as aluminum, gold, silver, nickel, palladium, and platinum; metal oxides such as indium and tin oxide and indium and zinc oxide; metal halides such as copper iodide; carbon black; and conductive polymers such as poly(3-methylthiophene), polypyrrole, and polyaniline. The anode can be formed by, for example, sputtering or vacuum deposition. The thickness of the anode is typically 5 to 1,000 nm, and preferably 10 to 500 nm. The anode may be the same as the substrate. Furthermore, it is also possible to laminate a different conductive material on the anode.

[0026] Hole Transport Layer A hole transport layer is provided on the anode. A hole injection layer may be provided between the two. These layers are known. Examples of hole transport materials include aromatic amine compounds having a starburst structure, spiro compounds such as 2,2',7,7'-tetrakis-(diphenylamino)-9,9'-spirobifluorene, and polymeric materials such as polyvinylcarbazole, polyvinyltriphenylamine, and tetraphenylbenzidine. When forming the hole transport layer by a coating method, one or more hole transport materials are added to and dissolved with additives such as a binder resin and a coating property improver to prepare a coating solution, which is then applied to the anode by a method such as spin coating and dried to form the hole transport layer. Alternatively, the hole transport layer may be formed by vacuum deposition.

[0027] Light-emitting layer The light-emitting layer may be formed from a single light-emitting layer, or may be formed by laminating multiple light-emitting layers in direct contact with each other. The light-emitting layer usually contains a host material and a light-emitting dopant. The light-emitting dopant may be a fluorescent material, a delayed fluorescent material, or a phosphorescent material. Two or more light-emitting dopants may be used in combination. The light-emitting layer of this invention contains an azaphenalene derivative represented by formula (I). The azaphenalene derivative represented by formula (I) may function as a light-emitting dopant or as a host material. An example of the host material is a carbazole-based compound. Host compounds consisting of carbazole-based compounds are known, for example, as described in Japanese Patent No. 5,866,902.

[0028] When the delayed fluorescent material is used as a delayed fluorescent dopant and the light-emitting layer contains a host material, the amount of the delayed fluorescent dopant contained in the light-emitting layer is, for example, 0.01 to 50% by weight, may be 0.1 to 20% by weight, or may be 0.01 to 10% by weight.

[0029] The thickness of the light-emitting layer is, for example, 1 to 300 nm, and may be 5 to 100 nm. The light-emitting layer can be formed in the same manner as the hole transport layer described above.

[0030] Electron Transport Layer The electron transport layer is a layer provided between the light-emitting layer and the cathode. The electron transport layer is intended to improve the light-emitting efficiency of the organic electroluminescent device. Examples of electron transport materials include metal complexes such as Alq3, metal complexes of 10-hydroxybenzo[h]quinoline, oxadiazole derivatives, distyrylbiphenyl derivatives, and n-type zinc selenide. The film thickness of the electron transport layer is, for example, 1 to 300 nm, and may be 5 to 100 nm. The electron transport layer can be formed by coating or vacuum deposition in the same manner as the hole transport layer.

[0031] Cathode The cathode is an electrode that serves to inject electrons into the electron transport layer. The cathode material can be the same as the anode. The cathode can be formed in the same manner as the anode.

[0032] The organic electroluminescent device of the present invention may be a single device, a device having an array structure, or a structure in which anodes and cathodes are arranged in an XY matrix. The organic electroluminescent device can be used for solar cells based on the same principle. Therefore, this specification also discloses an invention in which the organic electroluminescent device of the present invention is read as a solar cell.

[0033] 2. Manufacturing Method of Organic Electroluminescent Device The organic electroluminescent device described in this specification can be manufactured according to a known method in addition to containing an azaphenalene derivative in the light-emitting layer. An example of a known manufacturing method of an organic electroluminescent device is the example described in WO / 2021 / 256446.

[0034] The azaphenalene derivative of the present invention is a compound represented by the following formula (I).

[0035] In formula (I), X １ ~X ７ may be the same or different and represent a carbon atom (the carbon atom may be CH; the same applies below) or a nitrogen atom (the nitrogen atom may be NH); X １ ~X ７ At least one of the X is a nitrogen atom. １ ~X ７ The azaphenalene derivatives vary depending on the number and position of nitrogen atoms in X. Examples of azaphenalene derivatives include monoazaphenalene derivatives, diazaphenalene derivatives, triazaphenalene derivatives, tetraazaphenalene derivatives, pentaazaphenalene derivatives, hexaazaphenalene derivatives, and heptaazaphenalene derivatives. In these derivatives, the position of the carbon atom or nitrogen atom (the nitrogen atom may be NH) is optional. Examples of diazaphenalene derivatives include X １ and X ６ may be a nitrogen atom (or NH), or X ２ and X ５ may be a nitrogen atom (or NH). Diazaphenalene derivatives are described, for example, in JP-B 62-042950. An example of a triazaphenalene derivative is 1,3,4-triazaphenalene (JP-T 2006-527235). An example of a tetraazaphenalene derivative is 1,3,4,6-tetraazaphenalene (JP-T 2006-527235). An example of a pentaazaphenalene derivative is ２ ~X ５ and X ７ is a nitrogen atom (or NH).

[0036] The azaphenalene derivative represented by formula (I) is preferably a heptazine derivative represented by formula (I'). １ ~X ７ are all nitrogen atoms. Various heptaazaphenalene derivatives can be produced by referring to the method described in JP-A-2009-01194, for example. In formula (I'), R １ ~R ３ is synonymous with the above.

[0037] In the above formula (I) and formula (I′), R １ ~R ３ may be the same or different, and preferably represent a group represented by formula (II), formula (III) or formula (VI).

[0038]

[0039] In formula (II), * represents a linking moiety. ２１ is a C which may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ２２ and R ２３ may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group.２２ represents an integer of 0 to 3. ２３ represents an integer of 0 to 4. １１ ~X １７ may be the same or different and represent a carbon atom or a nitrogen atom.

[0040] In formula (II), X １１ ~X １７ are preferably all carbon atoms or one or two nitrogen atoms, and X １１ ~X １７ are preferably all carbon atoms or one nitrogen atom. １１ ~X １７ When contains a nitrogen atom, X １１ is preferably a nitrogen atom.

[0041] R ２１ ~R ２３ may be the same or different, and are a hydrogen atom, C １－４ Alkyl group, C １－４ an alkoxy group, or C １－４ C optionally substituted with an alkyl group ６－１０ An aryl group is preferred. １－４ C optionally substituted with an alkyl group ６－１０ The aryl group is preferably a phenyl group, a phenyl group substituted with a methyl group, or a phenyl group substituted with a t-butyl group. Examples of the phenyl group substituted with a methyl group include an o-methylphenyl group, a p-methylphenyl group, a 2,4-dimethylphenyl group, and a 2,4,6-trimethylphenyl group.

[0042] In formula (III), * represents a linking moiety. ３１ and R ３２ may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ３１ represents an integer of 0 to 4. ３２ represents an integer of 0 to 4. ２１ ~X ２８ may be the same or different and represent a carbon atom or a nitrogen atom.

[0043] X ２１ ~X ２８ are preferably all carbon atoms or one or two nitrogen atoms, and X ２１ ~X ２８ are preferably all carbon atoms or one nitrogen atom. ２１ ~X ２８ When contains a nitrogen atom, X ２４ or X ２５ is preferably a nitrogen atom.

[0044] R ３１ and R ３２ may be the same or different, and are a hydrogen atom, C １－４ Alkyl group, C １－４ an alkoxy group, or C １－４ C optionally substituted with an alkyl group ６－１０ An aryl group is preferred. Examples of the phenyl group substituted with a methyl group include an o-methylphenyl group, a p-methylphenyl group, a 2,4-dimethylphenyl group, and a 2,4,6-trimethylphenyl group.

[0045] R ３１ and R ３２ Either or both of may be a group represented by formula (II).

[0046] R ３１ and R ３２ Either or both of R may be a group represented by formula (III). ３１ and R ３２may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－６ Preferably, it is an alkyl group, and m ３１ represents an integer of 0 to 4, and m ３２ represents an integer of 0 to 4, and X ２１ ~X ２８ may be the same or different and represent a carbon atom or a nitrogen atom.

[0047] R ３１ and R ３２ is a group represented by formula (III), R １ ~R ３ It is preferable that any one or more of the above is a group represented by the following formula (III').

[0048] In formula (III′), X ２１ ~X ２８ may be the same or different and represent a carbon atom or a nitrogen atom. ３１１ and R ３２１ may be the same or different, and may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A; １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ３１１ represents an integer of 0 to 4. ３２１ represents an integer of 0 to 4. ３１１ and R ３２１ Preferred examples of are a hydrogen atom or C１－４ It is an alkyl group.

[0049] In formula (IV), * represents a linking moiety. ４１ is a C which may have a substituent selected from a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, and Group A １－１０ C which may have a substituent selected from the alkyl group and the A group １－１０ an alkoxy group, a C group optionally having a substituent selected from Group A; １－１０ an alkylthio group, a C group optionally having a substituent selected from Group A; ２－１０ an alkenyl group, C optionally having a substituent selected from Group A; ２－１０ an alkynyl group, C optionally having a substituent selected from Group A; １－１０ an alkylamino group, a C group optionally having a substituent selected from Group A; ６－１０ an aryl group or a C group optionally having a substituent selected from Group A; ７－１０ represents an aralkyl group. ４１ represents an integer of 0 to 5.

[0050] R ４１ may be the same or different, and are a hydrogen atom, C １－４ Alkyl group, C １－４ an alkoxy group, or C １－４ C optionally substituted with an alkyl group ６－１０ An aryl group is preferred. １－４ C optionally substituted with an alkyl group ６－１０ The aryl group is preferably a phenyl group, a phenyl group substituted with a methyl group, or a phenyl group substituted with a t-butyl group. Examples of the phenyl group substituted with a methyl group include an o-methylphenyl group, a p-methylphenyl group, a 2,4-dimethylphenyl group, and a 2,4,6-trimethylphenyl group.

[0051] R ４１ is -Si(R ４２ ) m ４２ R may be a silyl group represented by the formula: ４２ may be the same or different, and are a hydrogen atom, C １－１０ Alkyl group or C ６－１０ represents an aryl group, m ４２represents an integer of 1 to 3. In this case, R ４１ is preferably a group represented by the following formula (VI'). The silyl group is preferably a substituent at the meta position. ４２ is C １－４ A phenyl group which may be substituted with an alkyl group is preferred.

[0052] R ４１ is the number of adjacent R ４１ are taken together to form a five- or six-membered ring which may have a substituent, or two adjacent R ４１ R may be taken together to form a bicyclic group containing a five- or six-membered ring, which may have a substituent. The five- or six-membered ring may contain a heteroatom such as a nitrogen atom. ４１ is preferably a group represented by formula (VI'').

[0053]

[0054] R ４３ may be the same or different, and are a hydrogen atom, C １－１０ Alkyl group or C ６－１０ represents an aryl group, m ４３ is preferably an integer of 0 to 2. In formula (VI″), —(R ４３ ) m ４３ An example of is the diphenyl group.

[0055] In the above formula (I) and formula (I′), R １ ~R ３ is -N(R ５１ ) m ５１ R may be a group represented by formula (V). ５１ may be the same or different, and are a hydrogen atom, C １－４ Alkyl group, C １－４ an alkoxy group, or C １－４ C optionally substituted with an alkyl group ６－１０ An aryl group is preferred. １－４ C optionally substituted with an alkyl group ６－１０The aryl group is preferably a phenyl group, a phenyl group substituted with a methyl group, or a phenyl group substituted with a t-butyl group. Examples of the phenyl group substituted with a methyl group include an o-methylphenyl group, a p-methylphenyl group, a 2,4-dimethylphenyl group, and a 2,4,6-trimethylphenyl group. ５１ represents an integer of 0 to 2. ５１ is the number of adjacent R ５１ are taken together to form a five- or six-membered ring which may have a substituent, or two adjacent R ５１ may be taken together to form a bicyclic group optionally having a substituent containing a five- or six-membered ring. In these cases, the five- or six-membered ring may be a group having a hetero compound within the ring. In this case, an example of the group represented by formula (V) is an N-morpholinyl group.

[0056] Group A is a halogen atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an amino group; １ -C ６ Alkyl group; C ２ -C ６ Alkenyl group; C ２ -C ６ Alkynyl group; C １ -C ６ Alkoxy group; C １ -C ６ Alkylthio group; C ３ -C ７ Alicyclic hydrocarbon group; C ７ -C １６ Aralkyl group; Carbamoyl group; C ６ -C １０ aryl groups; and 5- to 7-membered aromatic heterocyclic groups.

[0057] This specification discloses all compounds of any combination of the above formulas.

[0058] This azaphenalene derivative has an energy level E Ｓ１ to the energy level E of the lowest triplet excited state Ｔ１ Energy difference ΔE minus ＳＴ -0.20 eV≦ΔE ＳＴ <0 eV is preferred. ＳＴWhen ΔE is a negative value, excited triplets that do not normally emit light can be quickly converted into singlets and used for light emission. This allows for the production of an organic EL element with high luminance, high efficiency, and high durability. ＳＴ -0.20 eV≦ΔE ＳＴ <-0.1 eV. ＳＴ If is too small, it can be predicted that the RISC from the lowest triplet excited state T1 to the lowest singlet excited state S1 will be in the inversion region in Marcus theory, and the rate constant will be small. ＳＴ is -0.15 eV≦ΔE ＳＴ <0 eV, or -0.10 eV≦ΔE ＳＴ The energy level E of the lowest singlet excited state may be <0 eV. Ｓ１ and the energy level E of the lowest triplet excited state Ｔ１ may be determined, for example, by using molecular orbital calculations, or may be determined from the results of fitting analysis, which will be described later.

[0059] When this azaphenalene derivative is used in the light-emitting layer of an organic electroluminescent device, the π-π ＊ Preferably, the azaphenalene derivative exhibits light emission derived from the transition. When the azaphenalene derivative is used in the light-emitting layer of an organic electroluminescent device, the azaphenalene derivative may have light absorption in the region of 300 to 420 nm.

[0060] It is preferable that this azaphenalene derivative does not enter an exciplex state when mixed with a host compound (for example, 4,4'-bis(carbazoyl)biphenyl (CBP) used in organic electroluminescent devices to form a thin film. Whether or not an exciplex state is entered can be determined by whether the emission region (or absorption region) of the azaphenalene derivative alone is maintained in the thin film obtained by mixing it with 4,4'-bis(carbazoyl)biphenyl (CBP). If the azaphenalene derivative (guest compound) forms an exciplex with the host compound and impairs the emission properties, the thin film will no longer show emission (or absorption) of the azaphenalene derivative alone.

[0061] C １－１０The alkyl group includes a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms. １－１０ Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, an n-pentyl group, an n-hexyl group, a 1-ethylpropyl group, and a 2,2-dimethylpropyl group. １－１０ The alkyl group is C ３－１０ It may be a cycloalkyl group. ３－１０ A cycloalkyl group means a saturated hydrocarbon ring having 3 to 10 carbon atoms. ３－１０ Examples of cycloalkyl groups are monocycloalkyl groups, bicycloalkyl groups, and tricycloalkyl groups. Examples of monocycloalkyl groups are cyclopropyl groups, cyclobutyl groups, cyclopentyl groups, cyclohexyl groups, cycloheptyl groups, and cyclooctyl groups.

[0062] C １－１０ The alkoxy group includes a linear or branched alkyloxy group having 1 to 10 carbon atoms. １－１０ Examples of alkoxy groups are methoxy, ethoxy, propoxy, isopropoxy, and tert-butoxy groups. １－１０ The alkoxy group may be a cycloalkoxy group.

[0063] C １－１０ The alkylthio group is C １－１０ It is a group in which the oxygen of an alkoxy group is replaced with sulfur. １－１０ Examples of the alkylthio group include a methylthio group, an ethylthio group, a propylthio group, an isopropylthio group, a butylthio group, an isobutylthio group, a sec-butylthio group, a tert-butylthio group, a pentylthio group, an isopentylthio group, a 2-methylbutylthio group, a neopentylthio group, a 1-ethylpropoxy group, a hexyloxy group, a 4-methylpentylthio group, a 3-methylpentylthio group, a 2-methylpentylthio group, a 3,3-dimethylbutylthio group, a 2,2-dimethylbutylthio group, a 1,1-dimethylbutylthio group, a 1,2-dimethylbutylthio group, a 1,3-dimethylbutylthio group, a 2,3-dimethylbutylthio group, and a 2-ethylbutylthio group.

[0064] C２－１０ The alkenyl group means a monovalent group resulting from the loss of one hydrogen atom from a straight-chain or branched-chain aliphatic hydrocarbon having 2 to 10 carbon atoms and a double bond. ２－１０ Examples of the alkenyl group include ethenyl, 1-propenyl, 2-propenyl, 2-methyl-1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 3-methyl-2-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, and 1-hexenyl. ２ -C ４ The alkenyl group includes an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, a 1-butenyl group, a 2-butenyl group, and a 3-butenyl group.

[0065] C ２－１０ The term "alkynyl group" refers to a monovalent group formed by the loss of one hydrogen atom from a straight-chain or branched-chain aliphatic hydrocarbon having 2 to 10 carbon atoms and a triple bond. ２－１０ Examples of alkynyl groups are ethynyl, 1-propynyl, 2-propynyl, 2-methyl-1-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 3-methyl-2-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, and 1-hexynyl groups.

[0066] C １－１０ The alkylamino group is a mono-C １－１０ Alkylamino group and diC １－１０ Mono C may be any of alkylamino groups. １－１０ The alkylamino group is an amino group in which one of the hydrogen atoms of the amino group is C １－１０ It is a group substituted with an alkyl group. １－１０ Examples of alkylamino groups include methylamino, ethylamino, n-propylamino, isopropylamino, n-butylamino, sec-butylamino, and tert-butylamino groups. １－１０ The alkylamino group is an amino group in which two hydrogen atoms of the amino group are C １－１０ It means a group substituted with an alkyl group. １－１０Examples of the alkylamino group are a dimethylamino group, a diethylamino group, an ethylmethylamino group, a di(n-propyl)amino group, a methylpropylamino group, and a diisopropylamino group.

[0067] C ６－１０ The aryl group means an aryl group having 6 to 10 carbon atoms. ６－１０ Examples of the aryl group are a phenyl group, a naphthyl group, and an anthryl group. The aryl group may be a heteroaryl group. A heteroaryl group is a group in which one or more carbon atoms constituting an aryl group are substituted with an atom selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of heteroaryl groups are furan, benzofuran, thiophene, benzothiophene, pyrrole, pyridine, pyrimidine, pyridazine, pyrazine, quinoline, isoquinoline, phthalazine, benzo-1,2,5-thiadiazole, benzothiazole, indole, benzotriazole, benzodioxolane, benzodioxane, benzimidazole, and carbazole.

[0068] C ７－１０ An aralkyl group refers to an alkyl group having 7 to 10 carbon atoms in which one of the alkyl hydrogen atoms is replaced by an aryl group.

[0069] Azaphenalene derivative having a group represented by formula (III) A preferred example of the azaphenalene derivative is R １ represents a group represented by formula (III). In formula (III), R ３１ and R ３２ may be the same or different and represent a hydrogen atom, a carboxy group, a cyano group, a nitro group, a methyl group, or an ethyl group. ３１ and R ３２ is preferably an electron-withdrawing group having a relatively small molecular weight. ３１ represents an integer of 0 to 4. ３２ represents an integer of 0 to 4. ２１ ~X ２８ represents a carbon atom. ２ and R ３ may be the same or different and represent a group represented by formula (IV).４１ represents a hydrogen atom, a hydroxy group, an amino group, a methyl group, an ethyl group, a propyl group, a butyl group, a methoxy group, an ethoxy group, a propoxy group, a methylamino group, a dimethylamino group, or a trimethylamino group. ４１ represents an integer of 0 to 3.

[0070] A preferred example of the azaphenalene derivative is R １ represents a group represented by formula (III). In formula (III), R ３１ and R ３２ represents a hydrogen atom. ２１ ~X ２８ represents a carbon atom. In this case, the group represented by formula (III) is a 9H-carbazol-9-yl group. ２ and R ３ may be the same or different and represent a group represented by formula (IV). ４１ represents a methyl group or a methoxy group. ４１ represents an integer of 1 to 3. ４１ is a methyl group, and when m is 1, R ４１ may be present. ４１ is a methyl group, and when m is 3, R ４１ may be present. ４１ is a methoxy group, and when m is 1, R ４１ may be present. ４１ is a methoxy group, and when m is 2, R ４１ may be present. ４１ is a methoxy group, and when m is 3, R ４１ A preferred example of such an azaphenalene derivative is HzCzM, which will be described later. ２ , HzCzMa ２ , HzCzA ２ is.

[0071] Azaphenalene derivative having a group represented by formula (II) A preferred example of the azaphenalene derivative is an azaphenalene derivative having a group represented by formula (II). １ ~R ３ may be the same or different and represent a group represented by formula (II). ２１ is C having a substituent selected from Group A ６－１０ represents an aryl group. ６－１０ An example of an aryl group is a phenyl group. ２１ is preferably a p-tert-butylphenyl group. A specific azaphenalene derivative having a group represented by formula (II) is HzTBPCz, which will be described later. ３ is.

[0072] Method for Producing Azaphenalene Derivatives and Heptazine Derivatives Known azaphenalene derivatives can be used as appropriate for the azaphenalene derivatives described herein. Furthermore, the azaphenalene derivatives described herein can also be obtained by converting various substituents and adjusting the conditions for various steps based on the synthesis examples of azaphenalene derivatives shown in the following examples. [Examples]

[0073] It is preferable that OLEDs have easy charge injection, high spin conversion efficiency, and high luminescence quantum yield. To achieve these properties, the molecular design of the luminescent material involves substituting electron donating groups to raise the HOMO and LUMO levels, and having azaphenalene (heptazine) in the central skeleton to reduce negative ΔE ＳＴ It is considered that the symmetry forbidden state can be alleviated by maintaining the above and introducing substituents (for example, two or more types). In the examples, by substituting various electron donating groups, the electron donating groups can change the HOMO and LUMO levels, the luminescence quantum yield, ΔE ＳＴ We investigated the impact on

[0074] HzTBPCz ３ Synthesis of HzTBPCz ３The synthesis of was carried out as follows: Trichloroheptazine (280 mg, 1.01 mmol) was dissolved in dichloroethane (25 mL), and 9-[4-(tert-butyl)phenyl]-9H-carbazole (1.22 g, 4.07 mmol) and AlCl ３ (530 mg, 3.97 mmol) was added at 0° C. The reaction solution was warmed to room temperature and stirred for 24 hours. The mixture was diluted with water and chloroform, and the separated organic layer was concentrated and then purified using a column to give a yellow solid (yield: 305 mg, 28.3%).

[0075]

[0076] It is believed that various substituents can be introduced into azaphenalene (heptazine) derivatives by the same method as above. That is, by replacing the chlorine atom in the trichloro compound with the desired substituent, the desired azaphenalene (heptazine) derivative can be obtained.

[0077] HzTBPCz ３ Evaluation of the physical properties of the obtained HzTBPCz ３ The physical properties of HzTBPCz were evaluated. ３ 1 is a graph showing the UV-Vis absorption spectrum and PL spectrum of HzTBPCz. ３ The graph on the right shows the UV-Vis absorption spectrum of HzTBPCz. ３ 1 and 2. Table 1 shows the PL intensity (arbitrary units) of HzTBPCz ３ In Table 1, λ ＰＬ denotes the maximum emission wavelength, and τ ＤＦ denotes the delayed fluorescence lifetime, and Φ ＰＬ denotes the luminescence quantum yield, and k ｒ denotes the radiative deactivation rate constant, k ｎｒ denotes the non-radiative deactivation rate constant, k ＩＳＣ denotes the intersystem crossing rate constant, and k ＲＩＳＣ denotes the inverse intersystem crossing rate constant, and so on.

[0078]

[0079] As shown in Figures 1 and 2 and Table 1, in a toluene solution, HzTBPCz ３ exhibited green luminescence with a maximum emission wavelength of 509 nm and an emission quantum yield of 81%. The delayed fluorescence lifetime was 597 ns, and the intersystem crossing rate constant and inverse intersystem crossing rate constant were >1.0 × 10 ７ s －１ and ΔE ＳＴ was 13 meV.

[0080] 5wt% HzTBPCz ３ : mCBP thin film (evaporation) 5 wt% HzTBPCz by vacuum evaporation method ３ HzTBPCz:mCBP thin films were prepared and their optical properties were evaluated. ３ 4 is a graph showing the PL spectrum of a HzTBPCz:mCBP thin film. ３ 3 and 4. TABLE 2 shows the PL intensity (arbitrary units) of the mCBP thin film. ３ τ indicates the physical properties of the mCBP thin film. １ shows a luminescence lifetime of 9.1 nm, and τ ２ indicates an emission lifetime of 160 nm, and τ ３ indicates the emission lifetime at 1186 nm.

[0081]

[0082] The emission wavelength of the obtained thin film coincided with the maximum emission wavelength in the above solution. ３ was found not to form an exciplex with mCBP.

[0083] A glass substrate with a 100 nm thick indium tin oxide (ITO) film was ultrasonically cleaned using a neutral detergent, ultrapure water, acetone, and 2-propanol in that order, boiled in 2-propanol, and then treated with UV ozone for 30 minutes. Subsequently, a 5 nm thick HAT-CN (2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene), a 1 nm thick F6TCNNQ (1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane), a 50 nm thick CCP (9-phenyl-3,9'-bicarbazole), a 30 nm thick mCBP (1,3-bis(N-carbazole)benzene), and a 30 nm thick HzTBPCz film were vacuum-deposited. ３ (5 wt%) mixed film, PPF (bis(diphenylphosphoryl)dibenzo[b,d]furan) with a thickness of 10 nm, B ３ An organic light-emitting device was fabricated by depositing PYPB (1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene), Liq (lithium 8-hydroxyquinolinate) with a thickness of 1 nm, and aluminum with a thickness of 100 nm. The light-emitting area of ​​the organic light-emitting device was 2.0 × 2.0 mm. ２ It was.

[0084] Fig. 5 is a graph showing the EL spectrum of the organic light-emitting device obtained in Example 1. Fig. 6 is a graph showing the current density-voltage-luminance characteristics of the organic light-emitting device obtained in Example 1. Fig. 7 is a graph showing the external quantum efficiency-luminance characteristics of the organic light-emitting device obtained in Example 1. Fig. 8 is a graph showing the current efficiency-luminance-power efficiency characteristics of the organic light-emitting device obtained in Example 1. The characteristics of the organic light-emitting device obtained in Example 1 are shown in Table 3.

[0085]

[0086] 5 to 8 and Table 3 show that the organic light-emitting devices obtained in the examples have desirable properties for organic light-emitting devices. It is believed that the above properties are maintained even when the basic skeleton is azaphenalene. It is also believed that the above properties are maintained even when the substituents of the heptazine derivative are appropriately substituted.

[0087] [Production Example] Compound (1) and Compound (5)

[0088] Cyameloyl chloride (55.3 mg, 0.20 mmol) was dissolved in anhydrous m-xylene (1 mL), and carbazole (40.1 mg, 0.24 mmol) was added at room temperature. The mixture was heated to 130°C, stirred for 24 hours, and then returned to room temperature. 5 mL of anhydrous m-xylene was added to the reaction solution, which was then cooled to 0°C. Aluminum chloride (80 mg, 0.6 mmol) was added, and the mixture was stirred at 0°C for 1 hour and at room temperature for 0.5 hours. Ice was added, and the mixture was stirred until the reddish-brown color of the reaction solution disappeared and the solution turned yellow. Chloroform was added to separate the organic layer, which was then dried over sodium sulfate and concentrated. Column purification was carried out (CHCl ３ :Hexane=60:40-100:0), the target product was obtained.

[0089] Compound (1): yellow solid, 8.7 mg (0.018 mmol, 9.0%) １ H NMR (600 MHz, CDCl ３ ) Delta [ppm] = 2.38 (s, 9H), 2.72 (s, 9H), 7.10 (s, 3H), 7.10 (d, J = 7.8 Hz, 3H), 8.14 (d, J = 7.8 Hz, 3H) MS (MALDI-TOF): 486.24 [calcd:485.23]

[0090] Compound (5): HzCzX ２ 　 Yellow solid, 3.3 mg (0.006 mmol, 3.0%) １ H NMR (600 MHz, CDCl ３) Delta [ppm] = 2.40 (s, 6H), 2.78 (s, 6H), 7.14 (s, 2H), 7.43 (dd, J = 7.8 Hz, 2H), 7.53 (dd, J = 7.8 Hz, 2H), 7.99 (d, J = 7.2 Hz, 2H), 8.17 (d, J = 7.8 Hz, 2H), 9.10 (d, J = 8.4 Hz, 2H) MS (MALDI-TOF): 547.24 [calcd: 546.23]

[0091] Compound (2): HzCzM ２

[0092] Carbazole (426.4 mg, 2.6 mmol) was dissolved in tetrahydrofuran (7 mL), and sodium hydride (102.0 mg, 2.6 mmol) was added at 0°C. After stirring for 30 minutes, cyameloyl chloride (705.0 mg, 2.6 mmol) was added dropwise to a tetrahydrofuran solution (7 mL) at 0°C. The mixture was stirred at that temperature for 2 hours and then at room temperature for an additional 0.5 hours. The reaction solution was concentrated under reduced pressure and dried. The dried solid (81.4 mg, 0.2 mmol) was dissolved in tetrahydrofuran (3 mL), and nickel(II) acetylacetonate (2.6 mg, 0.01 mmol) and 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (4.3 mg, 0.01 mmol) were added at room temperature. Subsequently, a 1.0 M solution of 2-mesitylmagnesium bromide in tetrahydrofuran (480 μL, 0.48 mmol) was added, and the mixture was stirred at room temperature for 21 hours. The reaction was stopped by adding a small amount of hydrochloric acid and water, and the mixture was extracted with chloroform. The organic layer was then dried over sodium sulfate and concentrated. Column purification was carried out (CHCl ３ / Hexane = 3:2-100:0), the target product was obtained as a yellow solid, 2.5 mg (0.0044 mmol, 2.2%). Note that uL means microliter. The same applies hereinafter.

[0093] １ H NMR (600 MHz, CDCl ３ ​) Delta [ppm] = 2.31 (s, 9H), 2.43 (s, 9H), 6.92 (s, 4H), 7.41 - 7.47 (m, 4H), 7.96 (d, J = 7.2 Hz, 2H), 9.05 (d, J = 8.4 Hz, 2H) MS (MALDI-TOF): 574.39 [calcd:574.26]

[0094] Compound (3): HzCzMa ２

[0095] Carbazole (192.3 mg, 1.2 mmol) was dissolved in tetrahydrofuran (5 mL), and sodium hydride (46.0 mg, 1.2 mmol) was added at room temperature. After stirring for 0.5 hours, the mixture was heated to 60°C and stirred for an additional hour, then cooled to room temperature. This solution was added dropwise to a tetrahydrofuran solution (10 mL) of cyameloyl chloride (316.8 mg, 1.2 mmol) at room temperature, and the mixture was stirred for 0.5 hours, then stirred at 50°C for 0.5 hours, and cooled to room temperature. Nickel(II) acetylacetonate (14.8 mg, 0.06 mmol) and 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (24.7 mg, 0.06 mmol) were added to the reaction mixture at room temperature. After stirring for 10 minutes, the mixture was cooled to -30°C, and a 0.5M solution of 2,4-dimethoxyphenylmagnesium bromide in tetrahydrofuran (4.6 mL, 2.3 mmol) was added, followed by stirring for 1.5 hours. The reaction mixture was poured into ice water to terminate the reaction, and after extraction with chloroform, the organic layer was dried over sodium sulfate and concentrated. Column purification was carried out (CHCl ３ / AcOEt=100:0-90:10), the target product was obtained as a yellow solid (trace).

[0096] １ H NMR (600 MHz, CDCl ３ ​) Delta [ppm] = 3.91 (s, 6H), 3.98 (s, 6H), 6.53 (d, J = 1.8 Hz, 2H), 6.60 (dd, J = 9.0Hz, 1.8 Hz, 2H), 7.40 (dd, J = 7.8Hz, 7.2 Hz, 2H), 7.50 (dd, J = 8.4 Hz, 7.2 Hz, 2H), 7.96 (d, J = 7.8 Hz, 2H), 8.31 (d, J = 9.0 Hz, 2H), 9.13 (d, J = 8.4 Hz, 2H) MS (MALDI-TOF): 611.48 [calcd:610.21]

[0097] Compound (4): HzCzA ２

[0098] Carbazole (272.5 mg, 1.63 mmol) was dissolved in tetrahydrofuran (5 mL), and sodium hydride (68.7 mg, 1.72 mmol) was added at room temperature. The mixture was stirred at 50°C for 0.5 hours and cooled to room temperature. This solution was added dropwise to a tetrahydrofuran solution (20 mL) of cyameloyl chloride (450.6 mg, 1.63 mmol) at room temperature, and the mixture was stirred at 50°C for 0.5 hours and cooled to room temperature. Nickel(II) acetylacetonate (20.9 mg, 0.082 mmol) and 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (34.9 mg, 0.082 mmol) were added to the reaction mixture at room temperature. After stirring for 5 minutes, the mixture was cooled to -60°C, and a 0.5M solution of 4-methoxyphenylmagnesium bromide in tetrahydrofuran (7.2 mL, 3.6 mmol) was added. The mixture was stirred at -60°C for 2 hours and at -30°C for 0.5 hours. The reaction mixture was poured into ice water to terminate the reaction, and after extraction with chloroform, the organic layer was dried over sodium sulfate and concentrated. Column purification was carried out (CHCl ３ / Hexane=50:50-80:20), the target compound was obtained as a yellow solid, 19.4 mg (0.035 mmol, 2.2%).

[0099] １ H NMR (600 MHz, CDCl ３ ​) Delta [ppm] = 3.94 (s, 6H), 7.03 (d, J = 8.4 Hz, 4H), 7.44 (dd, J = 7.2 Hz, 2H), 7.56 (dd, J = 8.1 Hz, 7.8 Hz, 2H), 7.99 (d, J = 7.8 Hz, 2H), 8.62 (d, J = 8.4 Hz, 4H), 9.14 (d, J = 7.8 Hz, 2H) MS (MALDI-TOF): 551.67 [calcd:550.19]

[0100] Compound (6): HzMCzM ２

[0101] 3,6-Dimethoxy-9H-carbazole (275.0 mg, 1.21 mmol) was dissolved in toluene (10 mL), and cyameluric acid chloride (304.1 mg, 1.10 mmol) was added. The mixture was stirred at 80°C for 4 hours. After cooling to room temperature, the reaction mixture was filtered, and the filtered product was dried under reduced pressure. The dried solid (211.7 mg, 0.45 mmol) was dissolved in tetrahydrofuran (5 mL), and nickel(II) acetylacetonate (5.8 mg, 0.023 mmol) and 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (9.7 mg, 0.023 mmol) were added at room temperature. Subsequently, a 1.0 M solution of 2-mesitylmagnesium bromide in tetrahydrofuran (1.1 mL, 1.1 mmol) was added, and the mixture was stirred at room temperature for 17 hours. The reaction was quenched by the addition of hydrochloric acid, and the mixture was extracted with chloroform. The organic layer was dried over sodium sulfate and concentrated. Column purification was carried out (CHCl ３ / AcOEt=100:0-98:2), the target compound was obtained as a yellow solid, 147.2 mg (0.23 mmol, 51%).

[0102] １ H NMR (600 MHz, CDCl ３ ​) Delta [ppm] = 2.30 (s, 6H), 2.42 (s, 12H), 6.91 (s, 4H), 7.01 (dd, J = 9.0 Hz, 2.7 Hz, 2H), 7.36 (d, J = 3.0 Hz, 2H), 8.95 (d, J = 9.0 Hz, 2H) MS (MALDI-TOF): 635.76 [calcd:634.28]

[0103] Compound (7): HzMCzMa ２

[0104] 3,6-Dimethoxy-9H-carbazole (187.5 mg, 0.83 mmol) was dissolved in toluene (7 mL), and cyameluric acid chloride (207.4 mg, 0.75 mmol) was added. The mixture was stirred at 80°C for 3.5 hours. After cooling to room temperature, the reaction mixture was filtered, and the collected solid was dried under reduced pressure. The dried solid (298.0 mg, 0.64 mmol) was dissolved in tetrahydrofuran (6 mL), and nickel(II) acetylacetonate (8.2 mg, 0.032 mmol) and 1,3-bis(2,6-diisopropylphenyl)imidazolium chloride (13.6 mg, 0.032 mmol) were added at room temperature. Subsequently, a 0.5 M solution of 2,4-dimethoxyphenylmagnesium bromide in tetrahydrofuran (3.1 mL, 1.54 mmol) was added, and the mixture was stirred at room temperature for 17 hours. The reaction was stopped by adding a small amount of hydrochloric acid and water, and the mixture was extracted with chloroform. The organic layer was then dried over sodium sulfate and concentrated. Column purification was carried out (CHCl ３ / MeOH=100:0-98:2), the target compound was obtained as a yellow solid, 14.4 mg (0.022 mmol, 3.4%).

[0105] １ H NMR (600 MHz, CDCl ３ ​) Delta [ppm] = 3.90 (s, 6H), 3.95 (s, 6H), 3.98 (s, 6H), 6.53 (d, J = 1.8 Hz, 2H), 6.60 (dd, J = 8.4 Hz, 2.1 Hz, 2H), 7.01 (dd, J = 9.0Hz, 2.4 Hz, 2H), 7.37 (d, J = 3.0 Hz, 2H), 8.30 (d, J = 8.4 Hz, 2H), 9.05 (d, J = 9.6 Hz, 2H) MS (MALDI-TOF): 671.52 [calcd:670.23]

[0106] The following reagents were obtained: 2-(9H-carbazol-9-yl)-5,8-dimethylheptazine 2-(9H-carbazol-9-yl)-5,8-bis(2,4-dimethoxyphenyl)heptazine 2-(3,6-dimethoxy-9H-carbazol-9-yl)-5,8-dimethylheptazine 2-(3,6-dimethoxy-9H-carbazol-9-yl)-5,8-bis(2,4-dimethoxyphenyl)heptazine 2-(9H-carbazol-9-yl)-5,8-bis(4-methoxyphenyl)heptazine 2-(3,6-dimethyl-9H-carbazol-9-yl)-5,8-bis(4-methoxyphenyl)heptazine 2-(3,6-dimethyl-9H-carbazol-9-yl)-5,8-dimorpholineheptazine 3-(9-phenylcarbazol-3-yl)carbazole-9-yl-5,8-dimesitylheptazine 2-(2,7-di-tert-butyl-9H-carbazol-9-yl)-5,8-dimesitylheptazine

[0107] The following solvents were used: Toluene for spectroscopic analysis: Fujifilm Wako Pure Chemical Industries, Ltd. 2-propanol (IPA) for electronics industry: Kanto Chemical Co., Ltd.

[0108] Experimental equipment and devices: Quartz substrate: Premium Glass; Luer-tip all-plastic syringe 1 mL [A8401-LT]: Osaka Chemical; MS PVDF syringe filter [PVDF013145]: Osaka Chemical; Glove box: VAC; Hot plate [BV-001]: SIBATA; Spin coater [MS-A100]: MIKASA

[0109] Measurement equipment: UV-3600i Plus ultraviolet / visible / near-infrared spectrophotometer: Shimadzu Corporation; FS5 Spectrofluorometer: EDINBURGH INSTRUMENTS; C9920-02 absolute PL quantum yield spectrometer: Hamamatsu; Optistat DN liquid nitrogen bath cryostat for optical measurements: Oxford Instruments

[0110] Thin Film Formation Method The thin film formation procedure was as follows: 1. Substrate Cleaning The quartz substrate was washed with chloroform and then boiled and washed with IPA for 5 minutes.

[0111] 2. Solution Preparation A 5 mg / mL solution was prepared in a glove box using chloroform as a solvent, with a mass ratio of guest molecule to host molecule of 0.05:4.95. If the host molecule was difficult to dissolve, it was heated to 50°C on a hot plate to dissolve it.

[0112] 3. Formation of Organic Film The prepared solution was filtered through a syringe filter and spin-coated onto a cleaned quartz substrate in a glove box. The spin-coating was performed at 1000 rpm for 20 seconds. The spin-coating was performed quickly to prevent crystallization of the organic film. The thin film was then dried under vacuum at room temperature.

[0113] The following nine compounds were also evaluated for their physical properties and theoretical calculations were carried out.

[0114] UV-vis absorption spectrum The UV-vis absorption spectrum was measured for each molecule (Toluene solution 10 －５ The results are shown in Figures 9 and 10. Figure 9 shows the ２ , HzCzMa２ , HzMCzM ２ , and HzMCzMa ２ 1 is a graph showing the UV-vis absorption spectrum of HzMCzMa at a wavelength of 325 nm. ２ HzCzM ２ , HzMCzM ２ , HzCzMa ２ and HzMCzM ２ FIG. 10 shows the HzCzA ２ , HzMeCzA ２ , HzMeCzMp ２ , HzBCzM ２ and HztBuCzM ２ 1 is a graph showing the UV-vis absorption spectrum of HzCzA at a wavelength of 350 nm. ２ , HzMeCzA ２ , HzMeCzMp ２ , HztBuCzM ２ and HzBCzM ２ Shows.

[0115] As shown in Figs. 9 and 10, HzCzM ２ , HzCzMa ２ , HzCzA ２ , and HzMeCzMp ２ In the case of , optical absorption was observed around 420 nm. This is due to the π-π ＊ Other molecules exhibit broad absorption at long wavelengths, which is thought to be due to the CT transition from the HOMO of the electron-donating group to the LUMO of heptazine.

[0116] PL spectrum and PLQY (Plasma Quantum Yield) The PL spectrum and PLQY were measured for each molecule at room temperature (in toluene solution 10 －５ The results are shown in Figures 11, 12, 13 and Table 4 (Table 3-1). ２ , HzCzMa ２ , HzMCzM ２ , and HzMCzMa ２1 is a graph showing the PL spectrum of HzCzM at a wavelength of 500 nm. ２ , HzCzMa ２ , HzMCzMa ２ and HzMCzM ２ FIG. 12 shows the HzCzA ２ , HzMeCzA ２ , HzMeCzMp ２ , HzBCzM ２ and HztBuCzM ２ 1 is a graph showing the PL spectrum of HzBCzM at a wavelength of 550 nm. ２ , HzMeCzA ２ , HztBuCzM ２ , HzCzA ２ and HzMeCzMp ２ FIG. 13 shows HzCzMeA ２ 1 is a graph showing the PL spectrum of

[0117]

[0118] As shown in Figures 11, 12, 13 and Table 4 (Table 3-1), HzCzM ２ , HzCzMa ２ , HzCzA ２ , HzMeCzMp ２ , HzCzMeA ２ In the case of , blue light emission with peaks at around 450 and 470 nm was observed, and a vibrational structure was observed. This indicates that these molecules have a π-π structure of the central skeleton of heptadine. ＊ Therefore, the PL spectrum exhibits vibrational structures that are thought to be due to the π-π transition. ＊ The emission is thought to be due to the CT transition, so it is highly likely that these molecules are suitable for organic EL devices. The other molecules have longer wavelengths and broader spectra, and it is thought that the emission is due to the CT transition from the LUMO of heptazine to the HOMO of the electron-donating group. Furthermore, the emission quantum yield is very low for molecules that exhibit a CT transition, and ＊ The molecules that exhibited the transition were relatively high. ２ , HzCzA ２In HzTFEX ２ We achieved a high luminescence quantum yield exceeding the value of

[0119] Transient PL decay The transient PL decay of each molecule was measured at room temperature and analyzed. (Toluene solution 10 －５ The results are shown in Figures 14, 15, 16 and Table 5 (Table 3-2). ２ , HzCzMa ２ , HzMCzM ２ , and HzMCzMa ２ FIG. 15 is a graph showing the room temperature transient PL decay of HzCzA. ２ , HzMeCzA ２ , HzMeCzMp ２ , HzBCzM ２ and HztBuCzM ２ FIG. 16 is a graph showing the room temperature transient PL decay of HzCzMeA. ２ 1 is a graph showing the room temperature transient PL decay of τ ＰＦ denotes the fluorescence lifetime, and A １ and A ２ denotes the pre-exponential coefficient, and Φ ＰＦ denotes the fluorescence quantum yield, and Φ ＤＦ indicates the delayed fluorescence quantum yield.

[0120]

[0121] As shown in Figures 14, 15, 16 and Table 5 (Table 3-2), HzCzM ２ , HzCzMa ２ , HzCzA ２ , and HzCzMeA ２ In the PL spectrum, two components, fluorescence and delayed fluorescence, were clearly observed. It was found that the delayed component was small in molecules that showed CT emission.

[0122] Fitting analysis results HzCzM showing delayed fluorescence ２ , HzCzMa ２ , HzMCzMa ２ , HzCzA ２ , and HztBuCzM ２ In the following S １ and T１ The rate constants for each transition were calculated using the rate equation for the population of , and the analysis was performed.

[0123] The results are shown in Figures 17 to 21 and Table 6 (Table 3-3). ２ 18 is a graph showing fitting analysis of HzCzMa ２ 19 is a graph showing fitting analysis of HzMCzMa ２ 20 is a graph showing fitting analysis of HzCzA. ２ 21 is a graph showing fitting analysis of HztBuCzM ２ 10 is a graph showing fitting analysis of

[0124]

[0125] HzMCzMa ２ , HztBuCzM ２ , and HzCzMeA ２ Ha K ＲＩＳＣ than k ＩＳＣ is large, so S １ T than １ The energy of ＳＴ is considered to be a positive value. ２ , HzCzMa ２ , and HzCzA ２ Ha K ＩＳＣ than k ＲＩＳＣ is large, T １ S than １ The energy of ＳＴ is considered to be a negative value. １ and T １ From the following equation, which assumes equilibrium between ＳＴ was estimated as shown in the table.

[0126] HzδCaX ２ Synthesis of

[0127] 2,5,8-Trichloroheptazine (0.0563 g, 0.201 mmol) was dissolved in m-xylene (0.0466 g, 0.438 mmol) and dichloroethane (6.0 mL), and AlCl ３ (0.0569 g, 0.426 mmol) was added at room temperature. The mixture was stirred at 40°C for 96 hours, and the solvent was evaporated under reduced pressure. A THF solution (6.0 mL) of δ-Carboline (0.0515 g, 0.306 mmol) treated with NaH (0.0085 g, 0.35 mmol) was added dropwise, and the mixture was stirred at room temperature for 72 hours. The reaction mixture was filtered, and the residue was purified by silica gel column chromatography (CHCl ３ ) and gel permeation chromatography (CHCl ３ ) to give the desired product as a yellow solid (0.0096 g, 8.7%). １ H NMR (400 MHz, CDCl ３ ): δ 9.31 (dd, J = 8.7 Hz, 1.4 Hz, 1H), 9.12 (d, J = 8.7 Hz, 1H), 8.65 (dd, J = 5.0 Hz, 1.4 Hz, 1H), 8.31 (dd, J = 7.3 Hz, 0.9 Hz, 1H), 8.19 (d, J = 7.8 Hz, 2H), 7.64 (td, J = 8.0 Hz, 1.4 Hz, 1H), 7.51 (t, J = 7.6 Hz, 1H), 7.43 (dd, J = 8.7 Hz, 4.6 Hz, 1H), 7.14-7.16 (m, 4H). 2.78 (s, 6H), 2.40 (s, 6H). MS (ASAP): m / z 548.35 [M+H] ＋ ; calcd. for C ３３ H ２６ N ９ 548.22.

[0128] HzPCz ３ Synthesis of

[0129] 2,5,8-Trichloroheptazine (0.119 g, 0.430 mmol) and 9-phenyl-9H-carbazole (0.396 g, 1.63 mmol) were dissolved in dichloromethane (25 mL), and the solution was heated at −78°C with AlCl ３ (0.219 g, 1.64 mmol) was added. The temperature was raised to 0°C and stirred for 24 hours. Water was added to quench the reaction, and the organic layer was extracted with CHCl ３ The extract was then concentrated under reduced pressure. ３ The target compound was obtained as a yellow solid (0.01 g, 0.03%). １ H NMR (600 MHz, Toluene-d ８ ): δ 9.92 (s, 3H), 9.07 (d, J = 8.4 Hz, 3H), 7.94 (d, J = 7.7 Hz, 3H), 7.34 (d, J = 8.6 Hz, 3H), 7.26-7.12 (m, 27H). 　 MS (ASAP): m / z 897.25 [M+H] ＋ ; calcd. for C ６０ H ３７ N １０ 897.31.

[0130] HzPαCa ３ Synthesis of

[0131] 6-Iodo-9-(phenyl)-9H-pyrido[2,3-b]indole (0.666 g, 1.80 mmol) was dissolved in THF (15 mL), and a solution of n-BuLi in n-hexane (1.5 M, 1.3 mL, 2.0 mmol) was added dropwise at -78°C, followed by stirring for 0.5 hours. ２ A THF solution (0.48 M, 4.6 mL, 2.2 mmol) of 2,5,8-Trichloroheptazine (0.111 g, 0.400 mmol) and Pd(t-Bu ３ P) ２(0.0062 g, 0.012 mmol) was added and stirred at room temperature for 84 hours. ４ The reaction was stopped by adding an aqueous Cl solution, and the organic layer was washed with water and ３ After extraction with Na ２ SO ４ The mixture was dried over 1000 kJ / min and concentrated under reduced pressure. ３ ) to obtain the desired product as a yellow solid (0.0098 g, 2.7%). １ H NMR (600 MHz, CDC1 ３ ) δ 9.52 (s, 3H), 8.80 (d, J = 8.5 Hz, 3H), 8.49-8.61 (m, 6H), 7.68 (d, J = 4.3 Hz, 3H), 7.55 (d, J = 8.7 Hz, 3H), 7.27-7.45 (m, 15H).

[0132] HzTBPαCa ３ Synthesis of

[0133] 9-(4-t-Butylphenyl)-6-iodo-9H-pyrido[2,3-b]indole (1.36 g, 3.60 mmol) was dissolved in THF (30 mL), and a solution of n-BuLi in n-hexane (1.5 M, 2.5 mL, 3.8 mmol) was added dropwise at -78°C, followed by stirring for 0.5 hours. ２ A THF solution (0.48 M, 9.0 mL, 4.3 mmol) of the above was added and stirred at 0°C for 1 hour. 2,5,8-Trichloroheptazine (0.221 g, 0.800 mmol) and PEPPSI-IPr (0.0048 g, 0.0071 mmol) were added and stirred at room temperature for 84 hours. Saturated NH ４ The reaction was stopped by adding an aqueous Cl solution, and the organic layer was washed with water and ３ After extraction with Na ２ SO ４ The mixture was dried over 1000 kJ / min and concentrated under reduced pressure. ３ ) to obtain the desired product as a yellow solid (0.032 g, 3.8%).１ H NMR (600 MHz, CDC1 ３ ) δ 9.48 (d, J = 1.6 Hz, 3H), 8.75 (dd, J = 1.6, 8.7 Hz, 3H), 8.53 (dd, J = 1.6, 4.7 Hz, 3H), 8.52 (dd, J = 1.6, 7.6 Hz, 3H), 7.65-7.68 (m, 6H), 7.56-7.59 (m, 6H), 7.53 (d, J = 8.8 Hz, 3H), 7.30 (dd, J = 4.7, 7.5 Hz, 3H), 1.44 (s, 27H). MS (MALDI): m / z 1068.28 [M+H] ＋ ; calcd. for C ６９ H ５７ N １３ 1068.49.

[0134] Hz3DPFO ３ Synthesis of

[0135] 3-Bromo-9,9-diphenyl-9H-fluorene (1.07 g, 2.69 mmol) was dissolved in THF (25 mL), and a solution of t-BuLi in n-pentane (1.6 M, 3.4 mL, 5.4 mmol) was added dropwise at -78°C, followed by stirring for 1 hour. ２ A THF solution (10 mL, 2.7 mmol) was added and stirred for 1.5 hours. ３ P) ２ (0.0175 g, 0.0342 mmol) was added and stirred at room temperature for 72 hours. ４ The reaction was stopped by adding an aqueous Cl solution, and the organic layer was washed with water and ３ After extraction with Na ２ SO ４ The mixture was dried over 1000 kJ / min and concentrated under reduced pressure. ３ ) to obtain the desired product as a yellow solid (0.0813 g, 11.7%).１ H NMR (600 MHz, C ２ D ２ Cl ４ ): δ 8.88 (s, 3H), 8.45 (d, J = 8.1 Hz, 3H), 7.96 (d, J = 7.7 Hz, 3H), 7.57 (d, J = 8.1 Hz, 3H), 7.43 (t, J = 6.2 Hz, 6H), 7.33 (t, J = 7.4 Hz, 3H), 7.25 - 7.16 (m, 30H). １３ C NMR (150 MHz, C ２ D ２ Cl ４ ): δ 175.77, 158.35, 157.90, 151.01, 144.80, 141.06, 138.93, 133.79, 129.96, 128.54, 128.40, 1,28.05 127.85, 126.97, 126.55, 126.20, 121.96, 120.94, 65.66. MS (APCI): m / z 1122.47 [M + H] ＋ ; calcd. for C ８１ H ５２ N ７ 1122.42.

[0136] HzCzSi ２ Synthesis of

[0137] It should be noted that there may be some inaccuracies in the original text, especially in the chemical formula and spectral data part. The above translation is based on the literal meaning as accurately as possible.2,5,8-Trichloroheptazine (0.0154 g, 0.550 mmol) and (3-Tributylstannyl)triphenylsilane (0.342 g, 0.550 mmol) were dissolved in toluene (25 mL), and palladium(II) acetate (0.0075 g, 0.033 mmol) and tricyclohexylphosphine (0.0019 g, 0.066 mmol) were added, followed by stirring at room temperature for 19 hours. Then, a THF solution (4 mL) of 9H-carbazole (0.0121 g, 0.724 mmol) treated with NaH (0.00197 g, 0.823 mmol) was added dropwise, and the mixture was stirred at room temperature for 24 hours. Water was added to stop the reaction, and the organic layer was extracted with CHCl ３ Extraction was performed using silica gel column chromatography (CHCl ３ The target compound was obtained as a yellow solid (trace). MS (ASPA): m / z 1006.38 [M] － ; calcd. for C ６６ H ４６ N ８ Si ２　 1006.34.

[0138] HzDMCzδCaX ２ Synthesis of

[0139] 2,5,8-Trichloroheptazine (0.0593 g, 0.214 mmol) was dissolved in m-Xylene (0.0493 g, 0.464 mmol) and dichloroethane (6.0 mL), and AlCl ３(0.0567 g, 0.425 mmol) was added at room temperature. The mixture was stirred at 40°C for 96 hours, and the solvent was evaporated under reduced pressure. A THF solution (6.0 mL) of 8-(1,8-dimethyl-9H-carbazol-9-yl)-δ-carboline (0.1084 g, 0.2999 mmol) treated with NaH (0.0145 g, 0.363 mmol) was added dropwise, and the mixture was stirred at room temperature for 96 hours. The reaction mixture was filtered, and the residue was purified by silica gel column chromatography (CHCl ３ :n-Hexene=4:1 　 ) to obtain the target compound as a yellow solid (0.0118 g, 7.44%). MS (ASAP): m / z 741.29 [M+H] ＋ ; calcd. for C ４７ H ３７ N １０ 741.32.

[0140] Table 7. PL properties in toluene solution

[0141] Table 8. Excited state rate constants and ΔE ＳＴ

[0142] OLED characteristics Device 1: ITO / HAT-CN (5 nm) / TAPC (40 nm) / CCP (10 nm) / 5wt% HzCzX ２ :CzSi (30 nm) / PPF (10 nm) / B3PyPB (35 nm) / Liq (1 nm) / Al (100 nm) Device 2: ITO / HAT-CN (5 nm) / TAPC (40 nm) / CCP (10 nm) / 3wt% HzTBPαCa ３ :mCBP (30 nm) / PPF (10 nm) / B3PyPB (40 nm) / Liq (1 nm) / Al (100 nm)

[0143] The organic EL spectrum is shown in Figure 22. The horizontal axis represents wavelength, and the vertical axis represents organic EL intensity (arbitrary units). The current density-voltage-luminance characteristics are shown in Figure 23. The horizontal axis represents voltage, and the vertical axis represents current density and luminance. The external quantum efficiency-luminance characteristics are shown in Figure 24. The vertical axis represents external quantum efficiency, and the horizontal axis represents luminance.

[0144] Table 9. OLED characteristics

[0145] Compared with the device described in N. Aizawa et al. Nature 609, 502-506 (2022), Devices 1 and 2 showed a lower driving voltage and an improved maximum external quantum efficiency. Furthermore, at 1000 cd m －２ The device exhibited excellent characteristics, maintaining a high maximum external quantum efficiency even at high brightness.

[0146] The present invention relates to an organic electroluminescent device. The organic electroluminescent device is used in various display devices, curved displays, televisions, monitors, etc. Therefore, the present invention can be used in technical fields related to display devices.

Claims

1. An azaphenalene derivative represented by formula (I) (In formula (I), X １ ~X ７ may be the same or different and each represents a carbon atom or a nitrogen atom. At least one of X １ ~X ７ is a nitrogen atom. R １ ~R ３ may be the same or different and each represents a group represented by formula (II), formula (III) or formula (VI). (In formula (II), * represents a linking moiety. R ２１ represents a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, a C １－１０ alkyl group which may have a substituent selected from Group A, a C １－１０ alkoxy group which may have a substituent selected from Group A, a C １－１０ alkylthio group which may have a substituent selected from Group A, a C ２－１０ alkenyl group which may have a substituent selected from Group A, a C ２－１０ alkynyl group which may have a substituent selected from Group A, a C １－１０ alkylamino group which may have a substituent selected from Group A, a C ６－１０ aryl group, or a C ７－１０ aralkyl group which may have a substituent selected from Group A. R ２２ and R ２３ may be the same or different and each represents a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, a C １－１０ alkyl group which may have a substituent selected from Group A, a C １－１０ alkoxy group which may have a substituent selected from Group A, a C １－１０ alkylthio group which may have a substituent selected from Group A, a C ２－１０ alkenyl group which may have a substituent selected from Group A, a C ２－１０ alkynyl group which may have a substituent selected from Group A, a C １－１０ alkylamino group which may have a substituent selected from Group A, a C ６－１０ An aryl group, or a C which may have a substituent selected from Group A ７－１０ represents an aralkyl group, and m ２２ represents an integer from 0 to 3, and m ２３ represents an integer from 0 to 4, and X １１ to X １７ may be the same or different and represent a carbon atom or a nitrogen atom.) (In formula (III), * represents a linking portion, and R ３１ and R ３２ may be the same or different and represent a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, a C which may have a substituent selected from Group A １－１０ alkyl group, a C which may have a substituent selected from Group A １－１０ alkoxy group, a C which may have a substituent selected from Group A １－１０ alkylthio group, a C which may have a substituent selected from Group A ２－１０ alkenyl group, a C which may have a substituent selected from Group A ２－１０ alkynyl group, a C which may have a substituent selected from Group A １－１０ alkylamino group, a C which may have a substituent selected from Group A ６－１０ aryl group, a C which may have a substituent selected from Group A ７－１０ aralkyl group or a group represented by formula (III), and m ３１ represents an integer from 0 to 4, and m ３２ represents an integer from 0 to 4, and X ２１ to X ２８ may be the same or different and represent a carbon atom or a nitrogen atom.) (In formula (IV), * represents a linking portion, and R ４１ represents a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, a C which may have a substituent selected from Group A １－１０ alkyl group, a C which may have a substituent selected from Group A １－１０ alkoxy group, a C which may have a substituent selected from Group A １－１０ alkylthio group, a C which may have a substituent selected from Group A ２－１０ alkenyl group, a C which may have a substituent selected from Group A ２－１０ An alkynyl group, a C which may have a substituent selected from Group A １－１０ An alkylamino group, a C which may have a substituent selected from Group A ６－１０ An aryl group, a C which may have a substituent selected from Group A ７－１０ An aralkyl group, -Si(R ４２ )m ４２ A silyl group represented by (R ４２ may be the same or different and represents a hydrogen atom, a C １－１０ alkyl group or a C ６－１０ aryl group, m ４２ represents an integer of 1 to 3. ) or two adjacent Rs ４１ together represent a five-membered or six-membered ring which may have a substituent, or two adjacent Rs ４１ together represent a bicyclic group which may have a substituent containing a five-membered or six-membered ring, and m ４１ represents an integer of 0 to 5, and Group A is a halogen atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an amino group; a C １ -C ６ alkyl group; a C ２ -C ６ alkenyl group; a C ２ -C ６ alkynyl group; a C １ -C ６ alkoxy group; a C １ -C ６ alkylthio group; a C ３ -C ７ alicyclic hydrocarbon group; a C ７ -C １６ aralkyl group; a carbamoyl group; a C ６ -C １０ aryl group; and a group consisting of a 5- to 7-membered aromatic heterocyclic group. ) ) An organic electroluminescent device containing the same in a light emitting layer.

2. The organic electroluminescent device according to claim 1, wherein the azaphenalene derivative represented by formula (I) is a heptazine derivative represented by formula (I'). (In formula (I'), R １ to R ３ are as defined in claim 1.) The organic electroluminescent device.

3. The organic electroluminescent device according to claim 2, wherein R ３１ and R ３２ may be the same or different and each represents a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, or a C １－１０ alkyl group which may have a substituent selected from Group A, a C １－１０ alkoxy group which may have a substituent selected from Group A, a C １－１０ alkylthio group which may have a substituent selected from Group A, a C ２－１０ alkenyl group which may have a substituent selected from Group A, a C ２－１０ alkynyl group which may have a substituent selected from Group A, a C １－１０ alkylamino group which may have a substituent selected from Group A, an C ６－１０ aryl group, or a C ７－１０ aralkyl group which may have a substituent selected from Group A, and R ４１ represents a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an amino group, or a C １－１０ alkyl group which may have a substituent selected from Group A, a C １－１０ alkoxy group which may have a substituent selected from Group A, a C １－１０ alkylthio group which may have a substituent selected from Group A, a C ２－１０ alkenyl group which may have a substituent selected from Group A, a C ２－１０ alkynyl group which may have a substituent selected from Group A, a C １－１０ alkylamino group which may have a substituent selected from Group A, an C ６－１０ aryl group, or a C ７－１０ aralkyl group which may have a substituent selected from Group A. The organic electroluminescent device.

4. The organic electroluminescent device according to claim 2, wherein R １ represents a group represented by the formula (III), and in the formula (III), R ３１ and R ３２ may be the same or different and each represents a hydrogen atom, a carboxy group, a cyano group, a nitro group, a methyl group, or an ethyl group, and m ３１ represents an integer of 0 to 4, and m ３２ represents an integer of 0 to 4, X ２１ to X ２８ each represents a carbon atom, and R ２ and R ３ may be the same or different and each represents a group represented by the formula (IV), and in the formula (IV), ４１ R represents a hydrogen atom, a hydroxy group, an amino group, a methyl group, an ethyl group, a propyl group, a butyl group, a methoxy group, an ethoxy group, a propoxy group, a methylamino group, a dimethylamino group, or a trimethylamino group, and m ４１ represents an integer of 0 to 3. The organic electroluminescent device.

5. The organic electroluminescent device according to claim 2, wherein R １ represents a group represented by the formula (III), and in the formula (III), R ３１ and R ３２ represent a hydrogen atom, X ２１ to X ２８ represent a carbon atom, R ２ and R ３ may be the same or different and represent a group represented by the formula (IV), and in the formula (IV), R ４１ represents a methyl group or a methoxy group, and m ４１ represents an integer of 1 to 3, the organic electroluminescent device.

6. The organic electroluminescent device according to claim 2, wherein R １ to R ３ may be the same or different and each represents a group represented by formula (II); in formula (II), R ２１ represents a C ６－１０ aryl group having a substituent selected from Group A, R ２２ and R ２３ each represent a hydrogen atom, and X １１ to X １７ each represent a carbon atom. An organic electroluminescent device.

7. The organic electroluminescent device according to claim 2, wherein R １ to R ３ represents a group represented by the formula (II), and in the formula (II), R ２１ represents a p-tert-butylphenyl group, R ２２ and R ２３ represent a hydrogen atom, and X １１ to X １７ represent a carbon atom, an organic electroluminescent device.

8. The organic electroluminescent device according to any one of claims 1 to 7, wherein the light-emitting layer further contains a host compound, and the azaphenalene derivative represented by the formula (I) has an energy difference ΔE Ｓ１ obtained by subtracting the energy level E Ｔ１ of the lowest triplet excited state from the energy level E ＳＴ of the lowest singlet excited state, satisfying -0.20 eV ≤ ΔE ＳＴ < 0 eV. The organic electroluminescent device.

9. The organic electroluminescent device according to any one of claims 1 to 7, wherein the light-emitting layer further contains a host compound, and the light-emitting layer exhibits light emission derived from π-π ＊ transition in a region having a wavelength of 400 nm or more and 700 nm or less.

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