Narrow Bandwidth Emitting Materials

Abstract

To provide a narrow-bandwidth luminescent material that has high color purity and is stable and to improve the stability of a luminescent device.SOLUTION: A narrow-bandwidth luminescent material uses a multiple resonance effect. The luminescent material has an energy difference between the lowest singlet excitation state and the lowest triplet state of, preferably, 0.30 eV or more, more preferably, 0.35 eV or more, and still more preferably, 0.40 eV or more. A luminescent device uses such a luminescent material as a terminal luminescent material of a TAF device.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a narrow-bandwidth luminescent material and a light-emitting device using the same, and also to a method for designing a narrow-bandwidth luminescent material and a program for executing the design method. [Background technology]

[0002] In recent years, it has been shown that the use of a narrow-bandwidth light-emitting compound, which is a multiple-resonance TADF material, as the terminal emitting material in a TADF-assisted fluorescence (TAF) system that uses a delayed fluorescent material (TADF material) as an assist dopant, or in a light-emitting device that uses a TADF material or an exciplex material as a host, is superior in terms of color purity and device life (see Non-Patent Document 1). When used as a terminal emitting material, triplet excitons are converted to singlets on the TADF material, which acts as an assist dopant, and then the excitons are transferred to the terminal emitting material via Förster energy transfer (FET). As a result, mainly singlet excitons are generated on the terminal emitting material, which emits light in the same way as photoexcitation. The rapid decay of singlet excitons generated in the TADF materials used as the host and assist dopants by the FET results in a shorter triplet exciton lifetime, thereby realizing a longer device lifetime. In addition, the terminal emitting material receives energy from the TADF material via the FET, generating singlet excitons. Narrow bandwidth emitting materials, which are multiple resonance TADF materials, have a very narrow half-width of emission and excellent color purity due to the absence of vibrational structures in the spectrum, and most of the emission is from singlets. However, due to the slow reverse intersystem crossing rate, in current-excited devices where 75% of excitons are generated as triplets, the triplet exciton lifetime is long, and when used simply as a TADF material without an assist dopant, the device lifetime is shortened. When a narrow-bandwidth light-emitting material, which is a multiple-resonance TADF material, is used as the terminal light-emitting material, this problem is resolved because energy is received from the TADF material by the FET, thereby realizing a longer device life. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] C.-Y. Chan, M. Tanaka, Y.-T. Lee, Y.-W. Wong, H. Nakanotani, T. Hatakeyama, and C. Adachi, "Stable pure-blue hyperfluorescence organic light-emitting diodes with high-efficiency and narrow emission", Nature Photonics, DOI: 10.1038 / s41566-020-00745-z Summary of the Invention [Problem to be solved by the invention]

[0004] There are various factors that hinder the extension of the lifetime of light-emitting devices using TADF materials, especially blue-emitting devices. One of these is the low TADF properties of the narrow-bandwidth emitting material used as the terminating material itself, i.e., the slow reverse intersystem crossing rate. To further improve devices, it is essential to improve the stability of triplet excitons generated in narrow bandwidth emitting materials and triplet exciton-emitting narrow bandwidth emitting materials. [Means for solving the problem]

[0005] The present invention provides a stable narrow bandwidth emissive material with high color purity by lowering the lowest triplet state energy of the narrow bandwidth emissive material, thereby reducing the TADF properties, and thereby improving the stability of light-emitting devices.

[0006] The present invention has been proposed based on these findings, and specifically includes the following: [1] A compound represented by the following general formula (1): General formula (1) M R -X (In the above formula, M R represents a partial structure that functions as a light-emitting material using the multiple resonance effect when X is a hydrogen atom, and X represents a polycyclic aromatic group containing three or more fused rings. [2] The compound according to [1], wherein the polycyclic aromatic group is an aromatic group containing three or more fused benzene rings (the ring skeleton constituting the aromatic group here may contain a heteroatom). [3] The compound according to [1] or [2], wherein the polycyclic aromatic group is a group bonded to the three or more fused rings at atoms constituting the ring skeleton. [4] The compound according to any one of [1] to [3], wherein the energy difference between the lowest singlet excited state and the lowest triplet state is 0.30 eV or more. [5] The compound according to any one of [1] to [3], wherein the energy difference between the lowest singlet excited state and the lowest triplet state is 0.35 eV or more. [6] The compound according to any one of [1] to [3], wherein the energy difference between the lowest singlet excited state and the lowest triplet state is 0.40 eV or more. [7] M R The compound according to any one of [1] to [6], wherein the compound contains one or more skeletal structures selected from the group consisting of the following structures 1 to 18: [ka] JPEG0007810961000002.jpg78170[8] M R is a group bonded to any one of the ring skeleton carbon atoms of the structures 1 to 18. [9] The compound according to [7] or [8], wherein X is an aromatic group containing four or more fused rings.

[10] The compound according to [9], wherein X is a group bonded to the four or more fused rings at an atom constituting the ring skeleton.

[11] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 1.

[12] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 2.

[13] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 3.

[14] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 4.

[15] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 5.

[16] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 6.

[17] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 7.

[18] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 8.

[19] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 9.

[20] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 10.

[21] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 11.

[22] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 12.

[23] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 13.

[24] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 14.

[25] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 15.

[26] MR The compound according to any one of [7] to

[10] , wherein the compound contains the structure 16.

[27] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 17.

[28] M R The compound according to any one of [7] to

[10] , wherein the compound contains the structure 18.

[29] The compound according to any one of [1] to

[28] , wherein X is an aromatic group containing 4 to 6 fused rings.

[30] The compound according to any one of [1] to

[28] , wherein X is an aromatic group containing four fused rings.

[31] The compound according to any one of [1] to

[28] , wherein X is a substituted or unsubstituted pyrenyl group.

[32] The compound according to any one of [1] to

[28] , wherein X is a substituted or unsubstituted 1-pyrenyl group.

[33] The compound according to any one of [1] to

[28] , wherein X is a substituted or unsubstituted 2-pyrenyl group.

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

[33] .

[0007]

[35] A light-emitting device using a narrow-bandwidth light-emitting material utilizing the multiple resonance effect, which has an energy difference between the lowest singlet excited state and the lowest triplet state of preferably 0.30 eV or more, more preferably 0.35 eV or more, and even more preferably 0.40 eV or more, as the terminal light-emitting material of a TAF device.

[36] A light-emitting device in which a narrow-bandwidth light-emitting material utilizing the multiple resonance effect is modified with a modifying group having a polycyclic aromatic or heterocyclic unit to produce a light-emitting material with an energy difference between the lowest singlet excited state and the lowest triplet state of preferably 0.30 eV or more, more preferably 0.35 eV or more, and even more preferably 0.40 eV or more, and the light-emitting material with reduced TADF properties is used as the terminal light-emitting material of a TAF device.

[37] The light-emitting device according to

[36] , wherein the difference in energy between the lowest triplet state of the modifying group and the lowest singlet excited state of the narrow bandwidth light-emitting material, which is the parent skeleton, is preferably 0.30 eV or more, more preferably 0.35 eV or more, and even more preferably 0.40 eV or more.

[38] The light-emitting device according to

[36] or

[37] , wherein the modifying group contains a polycyclic aromatic unit (e.g., a unit containing an anthracene ring, a phenanthrene ring, a tetracene ring, a pyrene ring, a chrysene ring, a perylene ring, a biphenylene ring, or a terphenylene ring, more preferably a unit containing four or more fused rings) or a heterocyclic polycyclic aromatic unit (e.g., a unit containing a pyridine ring, a pyrrole ring, a thiophene ring, or a furan ring, more preferably a unit containing four or more fused rings).

[39] The light-emitting device according to

[38] , wherein the light-emitting material is a narrow-bandwidth light-emitting material due to the multiple resonance effect, using the polycyclic aromatic unit or the heterocyclic-containing polycyclic aromatic unit as a structural skeleton, and has an energy difference between the lowest singlet excited state and the lowest triplet state of preferably 0.30 eV or more, more preferably 0.35 eV or more, and even more preferably 0.40 eV or more, as a terminal light-emitting material of the TAF device.

[40] The light-emitting device according to any one of

[34] to

[39] , which uses the light-emitting material as a terminal light-emitting material of a TAF device, and in which the proportion of fluorescent light-emitting components in the total light emitted is 98% or more.

[41] The light-emitting device according to any one of

[34] to

[40] , wherein the narrow-bandwidth light-emitting material utilizing the multiple resonance effect comprises the following skeleton (however, each hydrogen atom on the benzene ring in each of the following structures may be substituted with deuterium or a functional group. Specifically, the structure may be modified with an electron donor such as diphenylamine or carbazole, or an electron acceptor such as a cyano group or a fluorine atom, or may have a sterically bulky functional group such as a methyl group, an isopropyl group, or a tertiary butyl group introduced therein, or may have a monocyclic aromatic group such as a phenyl group introduced therein). [ka] JPEG0007810961000004.jpg126164

[0008]

[42] The light-emitting device according to any one of

[34] to

[40] , wherein the narrow-bandwidth light-emitting material utilizing the multiple resonance effect comprises the following skeleton (however, each hydrogen atom on the benzene ring in each of the following structures may be substituted with deuterium or a functional group. Specifically, the structure may be modified with an electron donor such as diphenylamine or carbazole, or an electron acceptor such as a cyano group or a fluorine atom, or may have a sterically bulky functional group such as a methyl group, an isopropyl group, or a tertiary butyl group introduced therein, or may have a monocyclic aromatic group such as a phenyl group introduced therein). [ka]

[43] A method for designing a narrow-bandwidth luminescent material with improved stability, characterized by substituting one or more hydrogen atoms constituting the luminescent material molecule using the multiple resonance effect with a polycyclic aromatic group containing three or more fused rings (the ring skeleton constituting the aromatic group here may contain a heteroatom).

[44] A method for designing a narrow-bandwidth luminescent material with improved stability, which includes assuming two or more molecules in which one or more hydrogen atoms constituting the luminescent material molecule using the multiple resonance effect are replaced with a polycyclic aromatic group containing three or more fused rings, evaluating the two or more assumed molecules by calculation, and selecting the optimal molecule (here, the ring skeleton constituting the aromatic group may contain a heteroatom).

[45] The method for designing a narrow-bandwidth luminescent material according to

[44] , wherein the evaluation includes evaluation of stability, preferably evaluation of materials with high stability.

[46] The method for designing a narrow-bandwidth luminescent material according to

[44] or

[45] , wherein the evaluation includes evaluating the magnitude of the energy difference between the lowest singlet excited state and the lowest triplet state, preferably evaluating a material with a large energy difference.

[47] The method for designing a narrow bandwidth luminescent material according to any one of

[44] to

[46] , wherein the evaluation includes evaluation of the half width of the emission spectrum, preferably including evaluating highly those with a small half width.

[48] ​​A program for implementing the design methods of

[43] –

[47] .

[49] A method for producing a narrow-bandwidth luminescent material with improved stability, characterized by substituting one or more hydrogen atoms constituting the luminescent material molecule using the multiple resonance effect with a polycyclic aromatic group containing three or more fused rings (the ring skeleton constituting the aromatic group here may contain a heteroatom). [Effects of the Invention]

[0009] According to the present invention, a stable narrow bandwidth luminescent material with high color purity can be provided, which can improve the stability of light emitting devices. [Brief explanation of the drawings]

[0010] [Figure 1] The molecular orbital distribution and energy diagram of CzBNNa and CzBNPyr obtained by TDDFT calculation. [Figure 2] The molecular orbital distribution and energy diagrams of BiPhOBPyr, BiPhOCzNBPyr, and PyrPhOCzNB obtained by TADFT calculations. [Figure 3] 1 shows the ultraviolet absorption spectrum, fluorescence spectrum, and phosphorescence spectrum of a toluene solution of CzBNNa. [Figure 4] 1 shows the ultraviolet absorption spectrum, fluorescence spectrum, and phosphorescence spectrum of a toluene solution of CzBNPyr. [Figure 5] The ultraviolet absorption spectrum, fluorescence spectrum, and phosphorescence spectrum of a toluene solution of BiPhOBPyr. [Figure 6] 1 shows the ultraviolet absorption spectrum, fluorescence spectrum, and phosphorescence spectrum of a toluene solution of BiPhOCzNBPyr. [Figure 7] 1 shows the ultraviolet absorption spectrum, fluorescence spectrum, and phosphorescence spectrum of a toluene solution of PyrPhOCzNB. [Figure 8] Emission spectra of a thin film of CzBNNa and mCBP, and a thin film of CzBNPyr and mCBP. [Figure 9] 1 shows the luminescence transient decay curves of thin films of CzBNNa and mCBP. [Figure 10] 1 shows the luminescence transient decay curves of thin films of CzBNPyr and mCBP. [Figure 11] 1 is a graph showing the change over time in luminescence when a toluene solution of CzBNNa is continuously irradiated with light of 300 to 400 nm. [Figure 12] 1 is a graph showing the change over time in luminescence when a toluene solution of CzBNPyr is continuously irradiated with light of 300 to 400 nm. [Figure 13] 1 is a graph showing deterioration over time of luminescence when a toluene solution of BiPhOCzNBPyr is continuously irradiated with light of 300 to 400 nm. [Figure 14] 1 is a graph showing the deterioration over time of luminescence when a toluene solution of BiPhOCzNB is continuously irradiated with light of 300 to 400 nm. [Figure 15] FIG. 2 is a schematic diagram showing the layer configuration and energy levels of the organic electroluminescence elements fabricated in Example 5 and Comparative Examples 5 and 6. [Figure 16] 1 shows the emission spectra of comparative element 4 using CzBNNa and element 5 using CzBNPyr. [Figure 17] 10 is a graph showing the current density-voltage characteristics of comparative element 4 using CzBNNa and element 5 using CzBNPyr. [Figure 18] 1 is a graph showing the external quantum efficiency (EQE)-luminance characteristics of a comparative device 4 using CzBNNa and a device 5 using CzBNPyr. [Figure 19] 1 is a graph showing the change over time in luminescence intensity in the absence of oxygen for Comparative element 4 using CzBNNa, Comparative element 5 using CzBNPyr, Comparative element 5 using CzBNPh, and Comparative element 6 using C56. [Figure 20] 1 is a graph showing the change over time in luminescence intensity in the presence of oxygen for Comparative element 4 using CzBNNa, Comparative element 5 using CzBNPyr, Comparative element 5 using CzBNPh, and Comparative element 6 using C56. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments or specific examples of the present invention, but the present invention is not limited to such embodiments or specific examples. In this specification, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to" as the lower and upper limits. In addition, the isotopes of hydrogen atoms present in the molecules of the compounds used in the present invention are not particularly limited, and for example, it is possible to use a compound in which all hydrogen atoms in the molecule are isotopic. 1 H, or part or all of 2 In a preferred embodiment of the present invention, all hydrogen atoms in the molecule may be H (deuterium D). 1 In one aspect of the invention, all hydrogen atoms in the molecule are 2 In one embodiment of the present invention, some of the hydrogen atoms in the molecule are 1 H and the remainder is 2 H (deuterium D). In the description of the present invention, the term "substituted" or "substituent" includes the following: 2 H (Deuterium D) 1 Hydrogen atom isotopes other than H are not included.

[0012] <Compound represented by general formula (1)> The compound of the present invention is represented by the following general formula (1). General formula (1) M R -X

[0013] In general formula (1), M Rrepresents a partial structure that, when X is a hydrogen atom, results in a molecule that functions as a light-emitting material with a multiple resonance effect. The phrase "using the multiple resonance effect" here means that two or more heteroatoms present in the molecule are resonating with each other, resulting in multiple resonance of the molecule as a whole. Examples of heteroatom types include boron, nitrogen, oxygen, and sulfur. A preferred molecule is one in which a structure containing two or more atoms (which may be the same or different) selected from the group consisting of boron, nitrogen, oxygen, and sulfur atoms is multiple resonance. A more preferred molecule is one in which a structure containing two or more atoms (which may be the same or different) selected from the group consisting of boron, nitrogen, and oxygen atoms is multiple resonance. A preferred embodiment of the present invention is a molecule in which a structure containing only boron and nitrogen atoms as heteroatoms is multiple resonance. Another preferred embodiment of the present invention is a molecule in which a structure containing only boron and oxygen atoms as heteroatoms is multiple resonance. Another preferred embodiment of the present invention is a molecule in which a structure containing only boron, nitrogen, and oxygen atoms is multiple resonance. In another preferred embodiment of the present invention, the molecule is a molecule having a structure containing only nitrogen atoms and oxygen atoms as heteroatoms, which exhibits multiple resonance. In another preferred embodiment of the present invention, the molecule is a molecule having a structure containing only nitrogen atoms as heteroatoms, which exhibits multiple resonance.

[0014] M R is preferably a group having a polycyclic structure. In particular, it is preferable that it contains a structure in which a ring containing a heteroatom and a benzene ring are fused as ring skeleton-constituting atoms. In particular, it is preferable that it contains a structure in which multiple benzene rings are fused via a ring containing a heteroatom. It is also preferable that it contains a structure in which two or more nitrogen-containing aromatic rings are fused. M RExamples of the groups include groups containing one or more skeletal structures selected from the group consisting of the above structures 1 to 18. One or more hydrogen atoms in structures 1 to 18 may be substituted with a substituent. The substituent may be selected, for example, from Substituent Group A described below, or from Substituent Group B described below. The number of substituents substituted on the skeletal structure may be, for example, 0 to 6, 0 to 4, 0 to 2, 1 to 6, or 2 to 6. Structures 1 to 18 may be unsubstituted (the number of substituents is 0).

[0015] M R is M R It is preferable that the carbon atom constituting the skeleton of the polycyclic structure constituting the structure 1 to 18 is a group that is bonded to X at the carbon atom constituting the ring skeleton of the polycyclic structure constituting the structure 1 to 18. For example, it is preferable that the carbon atom constituting the skeleton of the structure 1 to 18 is directly bonded to X. The carbon atom bonded to X is preferably a group that is bonded to X at the carbon atom constituting the ring skeleton of the polycyclic structure R When a boron atom is present in M, it is preferable that the carbon atom is in the para position with respect to the boron atom. R When a nitrogen atom is present in M, it is preferable that the carbon atom is in the meta position with respect to the nitrogen atom. R When an oxygen atom is present in M, it is preferable that the carbon atom is in the meta position with respect to the oxygen atom. R When the polycyclic structure constituting the formula (I) is an asymmetric structure containing a boron atom, a nitrogen atom, and an oxygen atom, such as structure 18, the carbon atom bonded to X may be a carbon atom at the para position or a carbon atom at the meta position relative to the boron atom, or may be a carbon atom at the meta position relative to the nitrogen atom, or may be a carbon atom at the meta position or a carbon atom at the para position relative to the oxygen atom.

[0016] In general formula (1), X represents a polycyclic aromatic group. The polycyclic aromatic group represented by X is an aromatic group containing three or more fused rings. The polycyclic aromatic group represented by X is preferably an aromatic group containing four or more fused rings, and particularly preferably an aromatic group containing four to six fused rings. The ring skeleton of the polycyclic aromatic group may contain a heteroatom (e.g., a nitrogen atom), but preferably does not contain one. In other words, the ring skeleton atoms are preferably composed only of carbon atoms. X is preferably a group bonded to the fused ring via a ring skeleton atom of the fused ring. The fused ring constituting X may have a substituent, and the substituent may be selected from, for example, the substituent group A described below or the substituent group B described below. Preferred specific examples of X include a 1-pyrenyl group and a 2-pyrenyl group, and the hydrogen atoms constituting these groups may also be substituted.

[0017] The compound represented by general formula (1) used in the present invention is preferably a narrow bandwidth light-emitting material. A narrow bandwidth light-emitting material is a light-emitting material whose emission spectrum has a narrow full width at half maximum (FWHM). The FWHM is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 35 nm or less.

[0018] The compound represented by general formula (1) is preferably represented by the following general formula (2). General formula (2) M R -Py In the above equation, M R represents a partial structure that functions as a light-emitting material utilizing the multiple resonance effect when X is a hydrogen atom, and Ry represents a substituted or unsubstituted pyrenyl group. The substituent of the pyrenyl group may be selected, for example, from Substituent Group A or Substituent Group B described below.

[0019] The compound represented by general formula (1) is also preferably represented by the following general formula: [ka] JPEG0007810961000007.jpg71170R, R1 Each independently represents a hydrogen atom or a substituent. The substituent may be selected from the substituent group A or the substituent group B described below. 1 Examples of the substituent represented by include a monocyclic aromatic group such as a phenyl group. The monocyclic aromatic group may be substituted with a substituent selected from Substituent Group A or Substituent Group B.

[0020] Specific examples of narrow-bandwidth luminescent materials utilizing the multiple resonance effect represented by general formula (1) include the following compounds. Preferred are the 1st, 5th, 6th, 10th, 11th, 15th, 16th, and 20th compounds substituted with a pyrenyl group. [ka] JPEG0007810961000009.jpg249167JPEG0007810961000010.jpg224166

[0021] <Delayed Fluorescence Materials (TADF Materials)> The compound represented by general formula (1) can be preferably used as a light-emitting material in a TAF system light-emitting device. That is, by using it in combination with an assist dopant of a delayed fluorescent material (TADF material), an excellent TAF system light-emitting device can be provided. The delayed fluorescent material to be used in combination with the compound represented by general formula (1) will be described below.

[0022] The delayed fluorescent material used in combination with the compound represented by general formula (1) is a delayed fluorescent material having a minimum excited singlet energy greater than that of the compound represented by general formula (1). When a host material is further used in combination, it is preferable that the delayed fluorescent material has a minimum excited singlet energy smaller than that of the host material. In the present invention, a "delayed fluorescent material" refers to an organic compound that undergoes reverse intersystem crossing from an excited triplet state to an excited singlet state in an excited state and emits fluorescence (delayed fluorescence) upon returning from the excited singlet state to the ground state. In the present invention, a delayed fluorescent material is one that emits fluorescence with an emission lifetime of 100 ns (nanoseconds) or longer when measured using a fluorescence lifetime measurement system (such as a streak camera system manufactured by Hamamatsu Photonics KK). The delayed fluorescent material (assist dopant) used in combination with the compound represented by general formula (1) is a material capable of emitting delayed fluorescence, but it is not essential that the delayed fluorescent material used in the light-emitting device of the present invention emits delayed fluorescence. The emission from the delayed fluorescent material used as an assist dopant is preferably less than 10% of the emission from the light-emitting device of the present invention, and may be, for example, less than 1%, less than 0.1%, less than 0.01%, or even below the detection limit. In a light-emitting device using a host material, the delayed fluorescent material as an assist dopant receives energy from the host material in an excited singlet state and transitions to the excited singlet state. Alternatively, the delayed fluorescent material as an assist dopant may receive energy from the host material in an excited triplet state and transition to the excited triplet state. The delayed fluorescent material as an assist dopant has a difference between the excited singlet energy and the excited triplet energy (ΔE ST ) is small, the assist dopant in the excited triplet state is likely to undergo reverse intersystem crossing to the assist dopant in the excited singlet state. The assist dopant in the excited singlet state generated by these pathways provides energy to the compound of general formula (1), causing the compound of general formula (1) to transition to the excited singlet state.

[0023] The delayed fluorescent material used as the assist dopant has a difference ΔE between the lowest excited singlet energy and the lowest excited triplet energy at 77 K. STis preferably 0.3 eV or less, more preferably 0.25 eV or less, more preferably 0.2 eV or less, more preferably 0.15 eV or less, even more preferably 0.1 eV or less, even more preferably 0.07 eV or less, even more preferably 0.05 eV or less, even more preferably 0.03 eV or less, and particularly preferably 0.01 eV or less. ΔE ST If the dc is small, reverse intersystem crossing from the excited singlet state to the excited triplet state is easily achieved by absorbing thermal energy, and thus the assist dopant functions as a thermally activated delayed fluorescent material. A thermally activated delayed fluorescent material absorbs heat emitted by a device and relatively easily undergoes reverse intersystem crossing from the excited triplet state to the excited singlet state, allowing the excited triplet energy to efficiently contribute to light emission.

[0024] In a preferred embodiment of the present invention, a compound represented by the following general formula (3) is used as the delayed fluorescent material serving as the assist dopant. [ka]

[0025] In general formula (3), R 21 ~R 23 one of the groups represents a cyano group or a group represented by the following general formula (4), and R 21 ~R 23 The remaining two and R 24 and R 25 At least one of R represents a group represented by the following general formula (5): 21 ~R 25 The remainder represents a hydrogen atom or a substituent (however, the substituent here does not represent a cyano group, a group represented by the following general formula (4), or a group represented by the following general formula (5)). [ka] In general formula (4), L 1 represents a single bond or a divalent linking group, and R 31 and R 32each independently represents a hydrogen atom or a substituent, and * represents the bonding position. [ka] In general formula (5), L 2 represents a single bond or a divalent linking group, and R 33 and R 34 each independently represents a hydrogen atom or a substituent, and * represents the bonding position.

[0026] R 21 ~R 23 Among them, R 21 or R 22 is preferably a cyano group or a group represented by general formula (4). In a preferred embodiment of the present invention, R 22 is a cyano group. In a preferred embodiment of the present invention, R 22 is a group represented by general formula (4). In one embodiment of the present invention, R 21 is a cyano group or a group represented by general formula (4). 23 is a cyano group or a group represented by general formula (4). 21 ~R 23 In one embodiment of the present invention, one of R 21 ~R 23 One of these is a group represented by general formula (4).

[0027] In a preferred embodiment of the present invention, L in general formula (4) 1 is a single bond. In one aspect of the present invention, L 1 is a divalent linking group, preferably a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group, more preferably a substituted or unsubstituted arylene group, and even more preferably a substituted or unsubstituted 1,4-phenylene group (with, for example, an alkyl group having 1 to 3 carbon atoms as the substituent). In one embodiment of the present invention, R in general formula (4) 31 and R 32are each independently one group or a combination of two or more groups selected from the group consisting of alkyl groups (e.g., having 1 to 40 carbon atoms), aryl groups (e.g., having 6 to 30 carbon atoms), heteroaryl groups (e.g., having 5 to 30 ring skeleton atoms), alkenyl groups (e.g., having 1 to 40 carbon atoms), and alkynyl groups (e.g., having 1 to 40 carbon atoms) (hereinafter, these groups are referred to as "groups of substituent group A"). In a preferred embodiment of the present invention, R 31 and R 32 are each independently a substituted or unsubstituted aryl group (e.g., having 6 to 30 carbon atoms), and examples of the substituent of the aryl group include the groups in Substituent Group A. In a preferred embodiment of the present invention, R 31 and R 32 are identical.

[0028] In a preferred embodiment of the present invention, L in general formula (5) 2 is a single bond. In one aspect of the present invention, L 2 is a divalent linking group, preferably a substituted or unsubstituted arylene group or a substituted or unsubstituted heteroarylene group, more preferably a substituted or unsubstituted arylene group, and even more preferably a substituted or unsubstituted 1,4-phenylene group (with, for example, an alkyl group having 1 to 3 carbon atoms as the substituent). In one embodiment of the present invention, R in general formula (5) 33 and R 34each independently represents a substituted or unsubstituted alkyl group (e.g., having 1 to 40 carbon atoms), a substituted or unsubstituted alkenyl group (e.g., having 1 to 40 carbon atoms), a substituted or unsubstituted aryl group (e.g., having 6 to 30 carbon atoms), or a substituted or unsubstituted heteroaryl group (e.g., having 5 to 30 carbon atoms). Examples of the substituents on the alkyl group, alkenyl group, aryl group, and heteroaryl group include a hydroxyl group, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), an alkyl group (e.g., having 1 to 40 carbon atoms), an alkoxy group (e.g., having 1 to 40 carbon atoms), an alkylthio group (e.g., having 1 to 40 carbon atoms), an aryl group (e.g., having 6 to 30 carbon atoms), an aryloxy group (e.g., having 6 to 30 carbon atoms), an arylthio group (e.g., having 6 to 30 carbon atoms), a heteroaryl group (e.g., having 5 to 30 ring skeleton atoms), a heteroaryloxy group (e.g., having 5 to 30 ring skeleton atoms), and a heteroarylthi group. Examples thereof include one group or a combination of two or more groups selected from the group consisting of an aryl group (e.g., having 5 to 30 ring skeleton atoms), an acyl group (e.g., having 1 to 40 carbon atoms), an alkenyl group (e.g., having 1 to 40 carbon atoms), an alkynyl group (e.g., having 1 to 40 carbon atoms), an alkoxycarbonyl group (e.g., having 1 to 40 carbon atoms), an aryloxycarbonyl group (e.g., having 1 to 40 carbon atoms), a heteroaryloxycarbonyl group (e.g., having 1 to 40 carbon atoms), a silyl group (e.g., a trialkylsilyl group having 1 to 40 carbon atoms), a nitro group, and a cyano group (hereinafter, these groups are referred to as "groups of substituent group B"). R 33 and R 34 may be bonded to each other via a single bond or a linking group to form a cyclic structure. 33 and R 34 When R is an aryl group, they are preferably bonded to each other via a single bond or a linking group to form a cyclic structure. The linking group here includes -O-, -S-, -N(R 35 )-, -C(R 36 )(R 37 )-, -C(=O)-, -O-, -S-, -N(R 35 )-, -C(R 36 )(R 37 )- is preferred, and -O-, -S-, -N(R 35)- is more preferred. R 35 ~R 37 each independently represents a hydrogen atom or a substituent. The substituent may be selected from the groups in the above-mentioned Substituent Group A or the groups in the below-mentioned Substituent Group B, and is preferably one group or a combination of two or more groups selected from the group consisting of alkyl groups having 1 to 10 carbon atoms and aryl groups having 6 to 14 carbon atoms.

[0029] The group represented by general formula (5) is preferably a group represented by the following general formula (6). [ka]

[0030] The compound represented by general formula (6) is more preferably a compound represented by any one of the following general formulae (7) to (12). [ka]

[0031] In the general formulas (6) to (12), L 11 and L 21 ~L 26 represents a single bond or a divalent linking group. 11 and L 21 ~L 26 For a description and preferred range of 2 Reference can be made to the description and preferred ranges of In the general formulas (6) to (12), R 41 ~R 110 R each independently represents a hydrogen atom or a substituent. 41 and R 42 , R 42 and R 43 , R 43 and R 44 , R 44 and R 45 , R 45 and R 46 , R 46 and R 47 , R 47 and R 48 , R51 and R 52 , R 52 and R 53 , R 53 and R 54 , R 54 and R 55 , R 55 and R 56 , R 56 and R 57 , R 57 and R 58 , R 58 and R 59 , R 59 and R 60 , R 61 and R 62 , R 62 and R 63 , R 63 and R 64 , R 65 and R 66 , R 66 and R 67 , R 67 and R 68 , R 68 and R 69 , R 69 and R 70 , R 72 and R 73 , R 73 and R 74 , R 74 and R 75 , R 75 and R 76 , R 76 and R 77 , R 77 and R 78 , R 78 and R 79 , R 79 and R 80 , R 81 and R 82 , R 82 and R 83 , R 83 and R 84 , R 84 and R 85 , R 86 and R 87 , R 87 and R 88 , R 88 and R 89 , R 89 and R 90 , R 91and R 92 , R 93 and R 94 , R 94 and R 95 , R 95 and R 96 , R 96 and R 97 , R 97 and R 98 , R 99 and R 100 , R 101 and R 102 , R 102 and R 103 , R 103 and R 104 , R 104 and R 105 , R 105 and R 106 , R 107 and R 108 , R 108 and R 109 , R 109 and R 110 may be bonded to each other to form a cyclic structure. The cyclic structure formed by bonding to each other may be an aromatic ring or an aliphatic ring, may contain a heteroatom, and may further be a fused ring of two or more rings. The heteroatom referred to here is preferably selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the cyclic structure formed include a benzene ring, a naphthalene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a pyrrole ring, an imidazole ring, a pyrazole ring, an imidazoline ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a cyclohexadiene ring, a cyclohexene ring, a cyclopentaene ring, a cycloheptatriene ring, a cycloheptadiene ring, a cycloheptaene ring, a furan ring, a thiophene ring, a naphthyridine ring, a quinoxaline ring, and a quinoline ring. For example, a ring formed by condensing multiple rings, such as a phenanthrene ring or a triphenylene ring, may also be formed. The number of rings contained in the group represented by general formula (6) may be selected from the range of 3 to 5, or may be selected from the range of 5 to 7. The number of rings contained in the groups represented by general formulas (7) to (12) may be selected from the range of 5 to 7, or may be 5. R 41 ~R110 Examples of the substituent that R may have include the groups in the above-mentioned substituent group B, and preferably an unsubstituted alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms which may be substituted with an unsubstituted alkyl group having 1 to 10 carbon atoms. In a preferred embodiment of the present invention, R 41 ~R 110 is a hydrogen atom or an unsubstituted alkyl group having 1 to 10 carbon atoms. In a preferred embodiment of the present invention, R 41 ~R 110 is a hydrogen atom or an unsubstituted aryl group having 6 to 10 carbon atoms. In a preferred embodiment of the present invention, R 41 ~R 110 are all hydrogen atoms. R in general formulas (6) to (12) 41 ~R 110 The carbon atoms to which CR is bonded (carbon atoms constituting the ring skeleton) may each independently be substituted with a nitrogen atom. 41 ~CR 110 may each independently be substituted with N. The number of nitrogen atoms substituted is preferably 0 to 4, and more preferably 1 to 2, among the groups represented by general formulas (6) to (12). In one embodiment of the present invention, the number of nitrogen atoms substituted is 0. Furthermore, when two or more groups are substituted with nitrogen atoms, the number of nitrogen atoms substituted in one ring is preferably 1. In the general formulas (6) to (12), X 1 ~X 6 represents an oxygen atom, a sulfur atom or NR. In one embodiment of the present invention, X 1 ~X 6 is an oxygen atom. In one aspect of the present invention, X 1 ~X 6 is a sulfur atom. In one embodiment of the present invention, X 1 ~X 6is NR. R represents a hydrogen atom or a substituent, and is preferably a substituent. Examples of the substituent include a substituent selected from the above-mentioned Substituent Group A. For example, an unsubstituted phenyl group or a phenyl group substituted with one group or a combination of two or more groups selected from the group consisting of alkyl groups and aryl groups can be preferably used. In the general formulae (6) to (12), * represents a bonding position.

[0032] Preferred compounds that can be used as delayed fluorescent materials that serve as assist dopants are listed below: In the structural formulas of the following exemplary compounds, t-Bu represents a tertiary butyl group. [ka] JPEG0007810961000017.jpg251166JPEG0007810961000018.jpg208170JPEG0007810961000019.jpg209170JPEG0007810961000020.jpg22915 7JPEG0007810961000021.jpg192164JPEG0007810961000022.jpg240170JPEG0007810961000023.jpg231151JPEG0007810961000024.jpg51170

[0033] The delayed fluorescent material serving as the assist dopant may be appropriately combined with other known delayed fluorescent materials in addition to those mentioned above. Furthermore, unknown delayed fluorescent materials may also be used. Examples of delayed fluorescent materials that are assist dopants include those described in paragraphs 0008 to 0048 and 0095 to 0133 of WO2013 / 154064, paragraphs 0007 to 0047 and 0073 to 0085 of WO2013 / 011954, paragraphs 0007 to 0033 and 0059 to 0066 of WO2013 / 011955, and paragraphs 0007 to 0033 and 0059 to 0066 of WO2013 / 081088. paragraphs 0008 to 0071 and 0118 to 0133, paragraphs 0009 to 0046 and 0093 to 0134 of JP 2013-256490 A, paragraphs 0008 to 0020 and 0038 to 0040 of JP 2013-116975 A, paragraphs 0007 to 0032 and 0079 to 0084 of WO2013 / 133359 A, paragraphs 0013 / 161437 A Paragraphs 0008 to 0054 and 0101 to 0121 of Japanese Patent Application Laid-Open No. 2014-9352, paragraphs 0007 to 0041 and 0060 to 0069 of Japanese Patent Application Laid-Open No. 2014-9224, paragraphs 0008 to 0048 and 0067 to 0076 of Japanese Patent Application Laid-Open No. 2017-119663, paragraphs 0013 to 0025 of Japanese Patent Application Laid-Open No. 2017-119664, paragraphs 0013 to 0026 of Japanese Patent Application Laid-Open No. 2017-119665, Examples include compounds encompassed by the general formulas described in paragraphs 0012 to 0025 of JP 17-222623 A, paragraphs 0010 to 0050 of JP 2017-226838 A, paragraphs 0012 to 0043 of JP 2018-100411 A, and paragraphs 0016 to 0044 of WO 2018 / 047853 A, particularly exemplary compounds that emit delayed fluorescence.Also, Japanese Patent Application Laid-Open No. 2013-253121, WO2013 / 133359, WO2014 / 034535, WO2014 / 115743, WO2014 / 122895, WO2014 / 126200, WO2014 / 136758, WO2014 / 133121, WO2014 / 136860, WO2014 / 196585, WO2014 / 189122, WO2014 / 168101, WO2015 / 00858 0 publication, WO2014 / 203840 publication, WO2015 / 002213 publication, WO2015 / 016200 publication, WO2015 / 019725 publication, WO2015 / 072470, WO2015 / 108049, WO2015 / 080182, WO2015 / 072537, WO2015 / 080183, JP2015-129240A, WO2015 / 129714, WO2015 / 129715, WO2015 / 133 It is also possible to employ luminescent materials that emit delayed fluorescence, such as those described in WO2015 / 136880, WO2015 / 137244, WO2015 / 137202, WO2015 / 137136, WO2015 / 146541, and WO2015 / 159541. The above publications described in this paragraph are incorporated herein by reference.

[0034] The delayed fluorescent material serving as the assist dopant preferably does not contain metal atoms. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms can be selected. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms can be selected. For example, a compound consisting of carbon atoms, hydrogen atoms, and nitrogen atoms can be selected.

[0035] <Host material> The light-emitting layer constituting the light-emitting device of the TAF system may contain a host material in addition to the compound represented by general formula (1) as the light-emitting material and the delayed fluorescent material (TADF material) as the assist dopant. The host material is a material with a higher minimum excited singlet energy than the compound represented by general formula (1) and the delayed fluorescent material as the assist dopant. The host material is preferably an organic compound that has hole transporting ability and electron transporting ability, prevents the emission wavelength from shifting to a longer wavelength, and has a high glass transition temperature. In a preferred embodiment of the present invention, the host material is selected from compounds that do not emit delayed fluorescence. The emission from the host material is preferably less than 1% of the emission from the light-emitting device of the present invention, more preferably less than 0.1%, and may be, for example, less than 0.01%, or even below the detection limit. It is preferable that the host material does not contain metal atoms. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, oxygen atoms, and sulfur atoms can be selected as the host material. For example, a compound consisting of atoms selected from the group consisting of carbon atoms, hydrogen atoms, nitrogen atoms, and oxygen atoms can be selected. For example, a compound consisting of carbon atoms, hydrogen atoms, and nitrogen atoms can be selected. Preferred compounds that can be used as the host material are listed below.

[0036] [ka] JPEG0007810961000026.jpg241170JPEG0007810961000027.jpg80170

[0037] <Light-emitting devices> (light-emitting layer) The light-emitting layer of the light-emitting device of the present invention comprises a light-emitting composition containing a compound represented by general formula (1) and a delayed fluorescent material serving as an assist dopant. The light-emitting composition may further contain a host material. In a preferred embodiment of the present invention, the light-emitting layer does not contain any compounds or metal elements that transfer charge or energy other than the compound represented by general formula (1), the delayed fluorescent material serving as an assist dopant, and the host material. The light-emitting layer may also be composed solely of the compound represented by general formula (1), the delayed fluorescent material serving as an assist dopant, and the host material. The light-emitting layer may also be composed solely of a compound consisting of atoms selected from the group consisting of carbon, hydrogen, nitrogen, boron, oxygen, sulfur, and fluorine atoms. For example, the light-emitting layer may be composed solely of a compound consisting of atoms selected from the group consisting of carbon, hydrogen, nitrogen, boron, oxygen, and fluorine atoms. In a preferred embodiment of the present invention, the light-emitting layer contains carbon, hydrogen, nitrogen, boron, oxygen, and fluorine atoms, and more preferably does not contain any other elements.

[0038] The light-emitting layer may be formed by a wet process or a dry process using a light-emitting composition containing at least the compound represented by general formula (1) and a delayed fluorescent material as an assist dopant. In a wet process, a solution containing a light-emitting composition is applied to a surface, and after the solvent is removed, a light-emitting layer is formed. Examples of wet processes include, but are not limited to, spin coating, slit coating, inkjet (spray) printing, gravure printing, offset printing, and flexographic printing. In a wet process, an appropriate organic solvent capable of dissolving the light-emitting composition is selected and used. In some embodiments, a substituent (e.g., an alkyl group) that increases the solubility in organic solvents can be introduced into the compound contained in the light-emitting composition.

[0039] A vacuum deposition method can be preferably used as the dry process. When using a vacuum deposition method, each compound constituting the light-emitting layer may be co-deposited from a separate deposition source, or all compounds may be mixed and co-deposited from a single deposition source. When a single deposition source is used, a mixed powder of all compounds may be used, a compressed compact of the mixed powder may be used, or a mixture of the compounds may be used in which the compounds are heated, melted, mixed, and then cooled. In some embodiments, a light-emitting layer having a composition ratio corresponding to the composition ratio of the compounds contained in a single deposition source can be formed by performing co-deposition under conditions where the deposition rates (weight loss rates) of the compounds contained in a single deposition source are the same or nearly the same. A light-emitting layer having a desired composition ratio can be easily formed by mixing multiple compounds in the same composition ratio as the light-emitting layer to be formed and using the resulting deposition source. In some embodiments, the temperature at which the weight loss rate of each co-deposited compound is the same can be identified, and that temperature can be used as the temperature during co-deposition. When the light-emitting layer is formed by a vapor deposition method, the molecular weight of each of the compound represented by general formula (1), the delayed fluorescent material serving as the assist dopant, and the host material is preferably 1500 or less, more preferably 1200 or less, even more preferably 1000 or less, and still more preferably 900 or less. The lower limit of the molecular weight may be, for example, 200, 400, or 600.

[0040] (Layer structure of light-emitting device) By forming a light-emitting layer made of a light-emitting composition containing at least a compound represented by general formula (1) and a delayed fluorescent material as an assist dopant, it is possible to provide an excellent organic light-emitting device such as an organic photoluminescence device (organic PL device) or an organic electroluminescence device (organic EL device). The thickness of the light-emitting layer can be, for example, 1 to 15 nm, 2 to 10 nm, or 3 to 7 nm. An organic photoluminescence element has a structure in which at least a light-emitting layer is formed on a substrate. An organic electroluminescence element has a structure in which at least an anode, a cathode, and an organic layer are formed between the anode and the cathode. The organic layer includes at least a light-emitting layer, and may consist of only the light-emitting layer, or may have one or more organic layers in addition to the light-emitting layer. Examples of such other organic layers include a hole transport layer, a hole injection layer, an electron blocking layer, a hole blocking layer, an electron injection layer, an electron transport layer, and an exciton blocking layer. The hole transport layer may be a hole injection transport layer having a hole injection function, and the electron transport layer may be an electron injection transport layer having an electron injection function.

[0041] The descriptions of use examples, devices, displays, screens, etc. described in paragraphs

[0141] to

[0169] and

[0192] to

[0242] of US2020 / 0168814A1 are hereby incorporated by reference in their entirety as part of this specification and serve to describe the present invention.

[0042] In some embodiments of the present invention, the following compounds can be preferably used as electron blocking materials. [ka]

[0043] In some embodiments of the present invention, the following compounds can be preferably used as hole-blocking materials. [ka]

[0044] Preferred examples of compounds that can be used as hole injection materials for organic electroluminescence devices are listed below. [ka]

[0045] Next, preferred examples of compounds that can be used as the electron injection material of an organic electroluminescence device will be listed. [ka]

[0046] Furthermore, examples of compounds that can be added to the organic layers of the organic electroluminescence device are as follows: For example, they can be added as stabilizing materials.

[0047] [ka] [Example]

[0048] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0049] Lowest excited singlet energy E S1 and the lowest excited triplet energy E T1 is measured by the following method, and ΔE ST is measured by the following method S1 and E T1 Using ΔE ST =E S1 -E T1 was calculated. (1) The lowest excited singlet energy, E S1 A sample with a thickness of 100 nm is prepared on a Si substrate by co-evaporating the compound to be measured and the host material so that the concentration of the compound to be measured is 6% by weight. The fluorescence spectrum of this sample is measured at room temperature (300K). Specifically, by integrating the emission from immediately after the excitation light is incident until 100 nanoseconds after the incident, a fluorescence spectrum is obtained with the emission intensity on the vertical axis and the wavelength on the horizontal axis. A tangent line is drawn to the rising edge on the short wavelength side of this emission spectrum, and the wavelength value λedge [nm] at the intersection of this tangent line and the horizontal axis is found. This wavelength value is converted to an energy value using the following conversion formula and the value E is obtained.S1 Let's say. Conversion formula: E S1 [eV]=1239.85 / λedge For measuring the emission spectrum, a nitrogen laser (MNL200, manufactured by Lasertechnik Berlin) can be used as the excitation light source, and a streak camera (C4334, manufactured by Hamamatsu Photonics KK) can be used as the detector. (2) Lowest excited triplet energy E T1 Lowest excited singlet energy E S1 The same sample used in the measurement is cooled to 77[K], excitation light is irradiated onto the phosphorescence measurement sample, and the phosphorescence intensity is measured using a streak camera. Specifically, by integrating the emission from 1 millisecond to 10 milliseconds after the excitation light is applied, a phosphorescence spectrum is obtained with the emission intensity on the vertical axis and the wavelength on the horizontal axis. A tangent line is drawn to the rising edge of the short wavelength side of this phosphorescence spectrum, and the wavelength value λedge[nm] at the intersection of this tangent line and the horizontal axis is found. This wavelength value is converted to an energy value using the following conversion formula, and the value E T1 Let's say. Conversion formula: E T1 [eV]=1239.85 / λedge The tangent to the rising edge of the phosphorescence spectrum on the short wavelength side is drawn as follows: When moving along the spectral curve from the short wavelength side of the phosphorescence spectrum to the shortest maximum of the spectral maxima, consider the tangent at each point on the curve toward the long wavelength side. The slope of this tangent increases as the curve rises (i.e., as the vertical axis increases). The tangent drawn at the point where this slope is at its maximum is considered to be the tangent to the rising edge of the phosphorescence spectrum on the short wavelength side. Note that a maximum point having a peak intensity that is 10% or less of the maximum peak intensity of the spectrum is not included in the above-mentioned maximum value on the shortest wavelength side, and the tangent drawn at the point where the slope value is the maximum value that is closest to the maximum value on the shortest wavelength side is defined as the tangent to the rising edge on the short wavelength side of the phosphorescence spectrum.

[0050] The light emission performance was evaluated using a source meter (Keithley: 2400 series), a semiconductor parameter analyzer (Agilent Technologies: E5273A), an optical power meter (Newport: 1930C), an optical spectrometer (Ocean Optics: USB2000), a spectroradiometer (Topcon: SR-3), and a streak camera (Hamamatsu Photonics K.K.: C4334).

[0051] The compound represented by formula (1) used in this example and comparative compounds are shown below. <Compound represented by formula (1) used in the examples> [ka] <Comparative Compound> [ka]

[0052] (Synthesis Example 1) Synthesis of CzBNNa, a compound in which a naphthyl group is introduced at the para-position of boron in Structure 5 (CzBN) [ka]

[0053] 2-Bromo-1,3-difluoro-5-iodobenzene (6.00 g, 18.8 mmol), naphthalen-2-ylboronic acid (3.56 g, 20.7 mmol), potassium carbonate (7.80 g, 56.4 mmol), and tetrakis(triphenylphosphine)palladium(0) (1.08 g, 0.9 mmol) were dissolved in a degassed tetrahydrofuran / water (2:1 by volume) mixture under a nitrogen atmosphere and heated to reflux overnight. After cooling to room temperature, the reaction mixture was poured into water (100 mL) and extracted with ethyl acetate. The organic layer was evaporated under reduced pressure to give a concentrate. The concentrate was purified by column chromatography using n-hexane as an eluent to give intermediate a1 (4.92 g, 83% yield), a white solid. 1H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.01 (s, 1H), 7.95-7.87 (m, 3H), 7.66 (d, 1H, J = 8.5 Hz), 7.55-7.53 (m, 2H), 7.32 (d, 2H, J= 8.5 Hz). MS (APCI) calcd. for C 16 H9BrF2: m / z = 317.99; found: 318.01 [M] + .

[0054] [ka]

[0055] Under a nitrogen atmosphere, 9H-carbazole (2.30 g, 13.8 mmol) was dissolved in N,N-dimethylformamide (anhydrous) (100 mL) in a round-bottom flask. A 60% mineral oil dispersion of sodium hydride (0.55 g, 13.8 mmol) was gradually added to the solution, and the mixture was stirred at room temperature for 1 hour. After this, intermediate a1 (2.00 g, 6.3 mmol) was added and the mixture was heated at 130 °C for 16 hours. Water was added to the reaction mixture to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 4:6 mixture of chloroform and hexane as the eluent to obtain intermediate a2 (3.04 g, 79% yield). 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.21 (d, 4H, J = 7.5 Hz), 8.11-8.08 (m, 3H), 7.92 (d, 1H, J = 8.5 Hz), 7.86-7.84 (m, 2H,), 7.75 (d, 1H, J = 7.5 Hz), 7.53-7.50 (m, 6H), 7.43-7.33 (m, 8H). MS (APCI) calcd. for C 40 H 25BrN2: m / z = 612.12; found: 612.27 [M] + .

[0056] [ka]

[0057] A solution of intermediate a2 (1.50 g, 2.4 mmol) in anhydrous toluene (60 mL) was slowly added with a 1.6 M hexane solution of n-butyllithium (1.80 mL, 2.9 mmol) at -30 °C under a nitrogen atmosphere. The mixture was warmed to room temperature and then heated to 60 °C and stirred for 2 h. Boron tribromide (0.35 mL, 3.6 mmol) was added to the mixture at -15 °C and stirred at room temperature for 2 h. N,N-diisopropylethylamine (0.98 mL, 5.2 mmol) was added at 0 °C. The mixture was warmed to room temperature and then heated to 110 °C and stirred for 10 h. The reaction mixture was cooled to room temperature, and aqueous sodium acetate and ethyl acetate were added. The precipitate (crude product) was filtered off. The crude product was dissolved in warm toluene, recrystallized, and then sublimed to obtain the desired CzBNNa (0.37 g, 28% yield). 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.98 (d, 2H, J = 7.5 Hz), 8.66 (s, 2H), 8.55 (d, 2H, J = 8.5 Hz), 8.39 (d, 2H, J = 7.0 Hz), 8.34 (s, 1H), 8.26 (d, 2H, J = 7.5 Hz), 8.12 (d, 1H, J = 8.5 Hz), 8.06 (t, 2H, J = 9.5 Hz), 7.99 (d, 1H, J = 8.0 Hz), 7.70 (t, 2H, J = 7.5 Hz), 7.65-7.59 (m, 4H), 7.47 (t, 2H, J = 7.5 Hz). MS (APCI) calcd. for C 40 H 23BN2: m / z = 542.20; found: 542.31 [M] + . Elemental analysis calcd. (%) for C 40 H 23 BN2: C 88.57, H 4.27, N 5.16; found: C 88.48, H 4.28, N 5.28.

[0058] (Synthesis Example 2) Synthesis of CzBNPyr, a compound in which a pyrenyl group is introduced at the para-position of boron in Structure 5 (CzBN) [ka]

[0059] 2-Bromo-1,3-difluoro-5-iodobenzene (3.20 g, 10.0 mmol), pyren-1-ylboronic acid (2.74 g, 11.0 mmol), potassium carbonate (4.16 g, 30.0 mmol), and tetrakis(triphenylphosphine)palladium(0) (0.58 g, 0.5 mmol) were dissolved in a degassed tetrahydrofuran / water (2:1 by volume) mixture under a nitrogen atmosphere and heated to reflux overnight. After cooling to room temperature, the reaction mixture was poured into water (70 mL) and extracted with ethyl acetate. The resulting organic layer was evaporated under reduced pressure to give a concentrate. The concentrate was purified by column chromatography using n-hexane as an eluent to give intermediate b1 (3.37 g, 85% yield), a white solid. 1 H NMR (500 MHz, CD2Cl2, 298K, relative to Me4Si): δ = 8.25-8.21 (m, 3H), 8.16-8.10 (m, 4H), 8.05 (t, 1H, J= 7.5 Hz), 7.94 (d, 1H, J = 7.5 Hz), 7.27 (d, 2H, J = 8.0 Hz). MS (APCI) calcd. for C 22 H 11 BrF2: m / z = 392.00; found: 392.08 [M]+ .

[0060] [ka]

[0061] Under a nitrogen atmosphere, 9H-carbazole (3.07 g, 18.4 mmol) was dissolved in N,N-dimethylformamide (anhydrous) (180 mL) in a round-bottom flask. A 60% mineral oil dispersion of sodium hydride (0.73 g, 18.4 mmol) was gradually added to the solution, and the mixture was stirred at room temperature for 1 hour. After this, intermediate b1 (3.30 g, 8.3 mmol) was added and the mixture was heated at 130 °C for 16 hours. Water was added to the reaction mixture to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 4:6 mixture of chloroform and hexane as the eluent to obtain intermediate b2 (4.32 g, 75% yield). 1 H NMR (500 MHz, CD2Cl2, 298K, relative to Me4Si): δ = 8.39 (d, 1H, J = 9.5 Hz), 8.27-8.09 (m, 11H), 8.06-8.02 (m, 3H), 7.53 (t, 4H, J = 8.0 Hz), 7.43 (d, 4H, J = 8.0 Hz), 7.34 (t, 4H, J = 7.5 Hz). MS (APCI) calcd. for C 46 H 27 BrN2: m / z = 686.14; found: 686.30 [M] + .

[0062] [ka]

[0063] A 1.6 M hexane solution of n-butyllithium (1.60 mL, 2.6 mmol) was slowly added to a solution prepared by dissolving intermediate b2 (1.50 g, 2.2 mmol) in anhydrous xylene (100 mL) under a nitrogen atmosphere at -30 °C. The mixture was warmed to room temperature and then heated to 60 °C and stirred for 2 h. Boron bromide (0.31 mL, 3.3 mmol) was added to the mixture at -15 °C and stirred at room temperature for 2 h. N,N-diisopropylethylamine (0.87 mL, 5.1 mmol) was added at 0 °C. The mixture was warmed to room temperature and then heated to 110 °C and stirred for 10 h. The reaction mixture was cooled to room temperature, and an aqueous solution of sodium acetate and ethyl acetate were added. The resulting precipitate (crude product) was filtered off. This crude product was dissolved in warm toluene and recrystallized, and then sublimated to obtain the target CzBNPyr in an amount of 0.47 g and a yield of 35%. 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 9.10 (d, 2H, J = 7.5 Hz), 8.71 (s, 2H), 8.54 (d, 1H, J = 7.5 Hz), 8.45 (d, 4H, J = 8.0 Hz), 8.41 (d, 1H, J = 7.0 Hz), 8.34-8.21 (m, 6H), 8.15-8.09 (m, 2H), 7.77 (t, 1H, J = 7.0 Hz), 7.51-7.41 (m, 6H). MS (APCI) calcd. for C 46 H 25 BN2: m / z = 616.21; found: 616.31 [M] + . Elemental analysis calcd. (%) for C 46 H 25 BN2: C 89.62, H 4.09, N 4.54; found: C 89.20, H 3.99, N 4.46.

[0064] (Synthesis Example 3) Synthesis of BiPhOBPyr, a compound in which a pyrenyl group is introduced into Structure 17 (BiPhOB) in which two phenyl groups have been introduced [ka]

[0065] 1-(4-Bromo-3,5-difluorophenyl)pyrene (2.00 g), [1,1'-biphenyl]-4-ol (2.16 g), and potassium carbonate (1.76 g) were dissolved in n-methylpyrrolidone (25 mL) under a nitrogen atmosphere and stirred at 170 °C for 14 hours. After cooling the reaction mixture to room temperature, water was added to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 4:6 mixture of chloroform and hexane as the eluent to obtain intermediate c1 (2.68 g, 76% yield). 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.14-7.94 (m, 8H), 7.84 (d, 1H), 7.55 (d, 4H), 7.50 (d, 4H), 7.36 (t, 4H), 7.27 (t, 2H), 7.20 (m, 4H), 7.03 (s, 2H).

[0066] [ka]

[0067] A 1.59 M hexane solution of n-butyllithium (1.00 mL) was slowly added to a solution prepared by dissolving intermediate c1 (1.00 g) in dehydrated xylene (20 mL) under a nitrogen atmosphere at -30 °C. The mixture was warmed to room temperature, then heated to 60 °C and stirred for 2 h. Boron tribromide (0.17 mL) was added to the mixture at -15 °C and stirred at room temperature for 2 h. N,N-diisopropylethylamine (0.60 mL) was added at 0 °C. The mixture was warmed to room temperature, then heated to 110 °C and stirred for 8 h. The reaction mixture was cooled to room temperature, and an aqueous solution of sodium acetate and ethyl acetate was added. The precipitate (crude product) was filtered off. The crude product was dissolved in warm toluene, recrystallized, and sublimed to obtain the desired BiPhOBPyr (0.25 g, 28% yield). 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 9.03 (s, 2H), 8.36-8.07 (m, 9H), 8.02 (d, 2H), 7.78 (d, 4H), 7.70 (d, 2H), 7.58 (s, 2H), 7.52 (t, 4H), 7.44 (t, 2H).

[0068] (Synthesis Example 4) Synthesis of BiPhOCzNBPyr, a compound in which a pyrenyl group is introduced into Structure 18 (BiPhOCzNB) in which a phenyl group is introduced [ka]

[0069] Under a nitrogen atmosphere, 9H-carbazole (2.23 g) was dissolved in N,N-dimethylformamide (anhydrous) (250 mL) in a round-bottom flask. A 60% mineral oil dispersion of sodium hydride (0.56 g) was gradually added to the solution, and the mixture was stirred at room temperature for 1 hour. After that, 1-(4-bromo-3,5-difluorophenyl)pyrene (5.00 g) was added and heated at 80 °C for 5 hours. Water was added to the reaction mixture to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 2:8 mixture of chloroform and hexane as the eluent to obtain intermediate d1 (2.30 g, 38% yield). 1 H NMR (500 MHz, CD2Cl2, 298K): δ = 8.29-8.06 (m, 11H), 7.71-7.68 (m, 2H), 7.49 (t, 2H), 7.36-7.30 (m, 4H).

[0070] [ka]

[0071] Intermediate d1 (2.30 g), [1,1'-biphenyl]-4-ol (0.87 g), and potassium carbonate (0.71 g) were dissolved in n-methylpyrrolidone (40 mL) under a nitrogen atmosphere and stirred at 170 °C for 12 hours. After cooling the reaction mixture to room temperature, water was added to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 3:7 mixture of chloroform and hexane as the eluent to give intermediate d2 (2.46 g, 84% yield). 1H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.25-8.18 (m, 6H), 8.10-7.97 (m, 5H), 7.63 (d, 2H), 7.60 (s, 1H), 7.55 (d, 2H), 7.50 (t, 2H), 7.45 (s, 1H), 7.42 (t, 2H), 7.37-7.30 (m, 7H).

[0072] [ka]

[0073] Intermediate d2 (1.20 g) was placed in a flask, dried under vacuum, and dissolved in anhydrous toluene (50 mL). The solution was cooled to -20 °C, and 1.59 M n-butyllithium solution (1.68 mL) was slowly added. After stirring at -20 °C for 2 hours, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.40 mL) was slowly added and stirred at room temperature for 4 hours. Water was added to the reaction mixture, and the mixture was extracted with dichloromethane. The resulting organic layer was dried over magnesium sulfate, filtered, and the filtrate was evaporated to dryness under vacuum. The dried product was purified by column chromatography using a 3:7 mixture of chloroform and hexane as an eluent to obtain intermediate d3 (0.80 g, 63% yield). 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.25 (d, 1H), 8.20-7.99 (m, 10H), 7.59-7.57 (m, 3H), 7.53 (d, 4H,), 7.46 (t, 2H), 7.45-7.39 (m, 3H), 7.32-7.27 (m, 5H), 0.70 (s, 12H).

[0074] [ka]

[0075] Intermediate d3 (0.32 g) and aluminum chloride (0.58 g) were dissolved in chlorobenzene and stirred at 120°C for 5 hours under a nitrogen atmosphere. Water was added to the reaction mixture to quench the reaction, followed by extraction with ethyl acetate. The resulting organic layer was dried over magnesium sulfate, filtered, and the filtrate evaporated to dryness under vacuum. The dried product was purified by column chromatography using a 1:9 chloroform:hexane mixed solvent as the eluent to obtain 0.05 g of the desired BiPhOCzNBPyr in a yield of 16%. 1 H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 9.08 (s, 1H), 9.99 (d, 1H), 8.56-8.07 (m, 12H,), 7.98 (d, 1H), 7.82 (d, 2H), 7.75 (t, 1H), 7.71-7.41 (m, 8H).

[0076] (Synthesis Example 5) Synthesis of PyrPhOCzNB, a compound in which a pyrenyl group is introduced at another position of Structure 18 (PhOCzNB) [ka]

[0077] Under a nitrogen atmosphere, 9H-carbazole (5.00 g) was dissolved in N,N-dimethylformamide (anhydrous) (180 mL) in a round-bottom flask. A 60% mineral oil dispersion of sodium hydride (1.32 g) was slowly added to the solution, and the mixture was stirred at room temperature for 1 hour. After that, 2-bromo-1,3-difluorobenzene (6.35 g) was added and the mixture was heated at 80 °C for 8 hours. Water was added to the reaction mixture to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 1:9 mixture of chloroform and hexane as the eluent to obtain intermediate e1 (5.18 g, 51% yield). 1H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.16 (d, 2H), 7.52-7.50 (m, 1H), 7.42 (t, 2H), 7.36-7.30 (m, 4H), 7.08 (d, 2H).

[0078] [ka]

[0079] Intermediate e1 (3.50 g), 4-(pyren-1-yl)phenol (3.33 g), and potassium carbonate (1.70 g) were dissolved in n-methylpyrrolidone (40 mL) under a nitrogen atmosphere and stirred at 170 °C for 12 hours. After cooling the reaction mixture to room temperature, water was added to quench the reaction, and the precipitate (crude product) was filtered off. The resulting crude product was purified by flash column chromatography (silica gel) using a 3:7 mixture of chloroform and hexane as the eluent to give intermediate e2 (4.10 g, 65% yield). 1 H NMR (500 MHz, CD2Cl2, 298K): δ = 8.27 (d, 1H), 8.24-8.03 (m, 10H), 7.70 (d, 2H), 7.60 (t, 1H,), 7.45 (t, 2H), 7.38-7.30 (m, 6H), 7.18 (d, 2H).

[0080] [ka]

[0081] Intermediate e2 (1.00 g) was placed in a flask, dried under vacuum, and dissolved in anhydrous toluene (120 mL). The solution was cooled to -20 °C, and 1.59 M n-butyllithium solution (1.63 mL) was slowly added. After stirring at -20 °C for 2 hours, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.32 mL) was slowly added and stirred at room temperature for 6 hours. Water was added to the reaction mixture, which was then extracted with dichloromethane. The resulting organic layer was dried over magnesium sulfate, filtered, and the filtrate was evaporated to dryness under vacuum. The dried product was purified by column chromatography using a 4:6 mixture of chloroform and hexane as the eluent to obtain intermediate e3 (0.65 g, 61% yield). 1 H NMR (500 MHz, CD2Cl2, 298K): δ = 8.26-7.99 (m, 11H), 7.69 (t, 1H), 7.63 (d, 2H), 7.43 (t, 2H), 7.33 (t, 2H), 7.30-7.24 (m, 6H), 0.66 (s, 12H).

[0082] [ka]

[0083] Intermediate e3 (0.50 g) and aluminum chloride (1.00 g) were dissolved in chlorobenzene and stirred at 120 °C for 5 hours under a nitrogen atmosphere. Water was added to the reaction mixture to quench the reaction, followed by extraction with dichloromethane. The resulting organic layer was dried over magnesium sulfate, filtered, and the filtrate evaporated to dryness under vacuum. The dried product was purified by column chromatography using a 1:9 mixture of chloroform and hexane as the eluent to obtain the desired PyrPhOCzNB in ​​a yield of 0.09 g and 24%. 1H NMR (500 MHz, CDCl3, 298K, relative to Me4Si): δ = 8.99-8.86 (m, 2H), 8.46-8.08 (m, 13H), 7.95-7.77 (m, 2H), 7.70-7.43 (m, 4H,), 7.35 (d, 1H).

[0084] (Time-dependent density functional (TDDFT) calculations) Molecular orbital distribution of each compound obtained by TDDFT calculation, HOMO and LUMO energies, lowest excited singlet energy S1, lowest excited triplet energy T1, difference ΔE between the lowest excited singlet energy S1 and the lowest excited triplet energy T1 ST , and oscillator strength f are shown in Figures 1 and 2. In each figure, the numbers on the top and bottom lines indicate the LUMO energy and HOMO energy, respectively, and the numbers on the two middle lines indicate the excited singlet energy S1 and excited triplet energy T1, respectively.

[0085] (Comparative Example 1) Fabrication of an organic photoluminescence device using CzBNNa In an Ar atmosphere glove box, a toluene solution of CzBNNa (concentration 10 -5 mol / L) was prepared. In addition, a vacuum of 8×10 was used to deposit the film on a quartz substrate. -5 CzBNNa and mCBP were evaporated from different evaporation sources under conditions of 0.1 Pa or less to form a 50 nm-thick thin film with a CzBNNa concentration of 1 wt % to prepare an organic photoluminescence device.

[0086] Example 1: Preparation of an organic photoluminescence device using CzBNPyr A toluene solution of CzBNPyr was prepared in the same manner as in Comparative Example 1, except that CzBNPyr was used instead of CzBNNa, and a thin film of CzBNPyr and mCBP was formed to prepare an organic photoluminescence device.

[0087] (Examples 2 to 4, Comparative Examples 2 and 3) Preparation of organic photoluminescence devices (toluene solutions) using other compounds A toluene solution of each compound was prepared in the same manner as in Comparative Example 1, except that the compounds shown in Table 1 were used instead of CzBNNa.

[0088] [Table 1]

[0089] [Evaluation of organic photoluminescence devices] The toluene solutions prepared in Comparative Example 1 and Examples 1 to 4 were measured for ultraviolet absorption spectra, fluorescence spectra using 340 nm excitation light, and phosphorescence spectra. The measurement results for the toluene solution of CzBNNa are shown in FIG. 3, those for CzBNPyr in FIG. 4, those for BiPhOBPyr in FIG. 5, those for BiPhOCzNBPyr in FIG. 6, and those for PyrPhOCzNB in ​​FIG. 7. In FIGS. 3 to 7, "UV@RT" indicates the ultraviolet absorption spectrum measured at room temperature, "FL@RT" indicates the fluorescence spectrum measured at room temperature, "FL@77K" indicates the fluorescence spectrum measured at 77 K, and "Ph@77K" indicates the phosphorescence spectrum measured at 77 K. The emission spectra of the thin films prepared in Comparative Example 1 and Example 1 are shown in Figure 8, and the transient decay curves of the emission measured at various temperatures are shown in Figures 9 and 10. The inset in Figure 10 shows the transient decay curve of the prompt fluorescence measured at 50 K. The transient decay curve of the CzBNPyr-doped film shown in Figure 10 did not show any delayed fluorescence at any temperature between 50 and 300 K. Table 2 shows various characteristic values ​​of the toluene solutions and thin films prepared in Comparative Example 1 and Example 1, and Table 3 shows various characteristic values ​​of the toluene solutions prepared in Examples 2 to 4. In each table, λabs is the maximum absorption wavelength, λmax is the maximum emission wavelength, Stokes shift is the difference between λmax and λabs, FWHM is the full width at half maximum of the emission peak, Φ Ar is the photoluminescence (PL) quantum yield measured in an argon atmosphere, ΔE ST is the difference ΔE between the lowest excited singlet energy S1 and the lowest excited triplet energy T1 ST , τ pis the emission lifetime of the instantaneous fluorescence, τ d is the emission lifetime of delayed fluorescence, K r is the rate constant of the radiative transition, K nr is the rate constant for radiationless transition, k ISC is the rate constant of intersystem crossing, k RISC is the rate constant for reverse intersystem crossing.

[0090] [Table 2]

[0091] [Table 3]

[0092] In addition, the toluene solutions (3 mL) prepared in Examples 1 and 3 and Comparative Examples 1 to 3 were subjected to irradiating with light passing through a 300 to 400 nm bandpass filter at 5 mW / cm 2 The degradation of the luminescence intensity over time was measured by continuous irradiation at an irradiation power of 1000 Hz, and the results are shown in Figures 11 to 14. The time LT90 required for the luminescence intensity to fall to 90% of the initial value was calculated from each figure, and the results are shown in Tables 4 and 5. The degradation of the luminescence intensity over time was measured in air (in the presence of oxygen) and in a nitrogen atmosphere (in N2 (in the absence of oxygen)). The degradation observed in air corresponds to the degradation of singlet excitons, while the degradation observed in a nitrogen atmosphere corresponds to the degradation of singlet and triplet excitons. Table 4 also lists the λmax, FWHM, and Φ shown in Table 2. Ar , ΔE ST and PL quantum yield Φ measured in air Air is also shown.

[0093] [Table 4]

[0094] [Table 5]

[0095] When a phenyl group (Ph), a naphthyl group (Na), or a pyrenyl group (Pyr) was introduced to the para-position of the boron in CzBN (Structure 5), a type of multiple-resonance narrow-band emitting TADF material, compounds with almost the same emission wavelength, Stokes shift, and spectral half-width were obtained. ST We found that the phenyl-modified (CzBNPh) and naphthyl-modified (CzBNNa) triplet excitons had the same 0.15 eV as the unmodified CzBNP, while the pyrenyl-modified (CzBNPyr) had a very low triplet exciton energy of 0.61 eV, indicating that it did not exhibit TADF properties. The emission quantum yields for the unmodified CzBNP were 99%, while those for the phenyl-modified CzBNP, naphthyl-modified CzBNN, and pyrenyl-modified CzBNPyr were 99%, 77%, and 83%, respectively, demonstrating high luminescence. We also evaluated other compounds with multiple resonance structures, such as PhOB (structure 17) and PhOCzNB (structure 18), in which a pyrenyl group was introduced at the para-position of the boron atom (BiPhOBPyr, BiPhOCzNBPyr), and a compound in which a pyrenyl group was introduced at another position of structure 18 (PyrPhOCzNB). All of these compounds exhibited low T1 energy, high PL quantum yield, narrow spectral half-width, and small Stokes shift, which were favorable characteristics. Furthermore, when the lifetime (LT90) of BiPhOCzNBPyr was compared with that of the unmodified compound (BiPhOCzNB) without the pyrenyl group, it was found that although the S1 energy was comparable, BiPhOCzNBPyr exhibited a longer lifetime than BiPhOCzNB. From the above, it has been demonstrated that by introducing polycyclic aromatic groups such as pyrene into compounds that exhibit TADF properties due to the multiple resonance effect in this invention, triplet excitons can be efficiently removed without impairing the luminescence properties, thereby providing a highly stable narrow-band luminescent material.

[0096] [Fabrication of electroluminescence devices] The layer structure and energy levels of each layer of the organic electroluminescence devices fabricated in the following Examples and Comparative Examples are shown in Figure 15. In Figure 15, the numbers written below each layer indicate the HOMO energy, and the numbers written above indicate the LUMO energy. The emitter is the dopant used in Example 5 and Comparative Examples 4 and 5: CzBNNa in Comparative Example 4, CzBNPyr in Example 5, and CzBNPh in Comparative Example 5. C56 is the dopant used in Comparative Example 6.

[0097] (Comparative Example 4) Fabrication of an organic electroluminescence device using CzBNNa Each thin film was deposited by vacuum deposition on a glass substrate with an anode made of indium tin oxide (ITO) with a thickness of 100 nm, at a vacuum of 6×10 -5 The organic electroluminescent device was fabricated by laminating the layers in a Pa. First, HAT-CN was deposited on ITO to a thickness of 10 nm, and then Tris-PCz was deposited on top of that to a thickness of 30 nm. Next, mCBP was deposited to a thickness of 5 nm. Next, CzBNNa and mCBP were co-evaporated from separate evaporation sources to form a 30 nm thick layer as the light-emitting layer. The CzBNNa concentration was 0.5 wt%. Next, SF3-TRZ was deposited to a thickness of 10 nm. Liq and SF3-TRZ were co-evaporated from separate evaporation sources to form a 20 nm thick layer on top of that. The Liq concentration was 30 wt%. Liq was then deposited to a thickness of 2 nm, and then aluminum (Al) was evaporated to a thickness of 100 nm to form a cathode, producing an organic electroluminescent device (Comparative Device 4).

[0098] (Example 5, Comparative Examples 5 and 6) Preparation of organic electroluminescence devices using other compounds as dopants Organic electroluminescence devices (device 5 and comparative devices 4 to 6) were prepared in the same manner as in Comparative Example 4, except that the compounds shown in Table 6 were used instead of CzBNNa when forming the light-emitting layer. Here, the concentrations of CzBNPyr and CzBNPh in the light-emitting layer were 5 wt %, and the concentration of C56 in the light-emitting layer was 20 wt %.

[0099] [Table 6]

[0100] [Evaluation of organic electroluminescence devices] The emission spectra of Comparative Device 4 and Device 5 are shown in Figure 16, their current density-voltage characteristics are shown in Figure 17, and their external quantum efficiency (EQE)-luminance characteristics are shown in Figure 18. The time-dependent changes in emission intensity measured in a nitrogen atmosphere (in the absence of oxygen) for Device 5 and Comparative Devices 4 to 6 are shown in Figure 19, and the time-dependent changes in emission intensity measured in air (in the presence of oxygen) are shown in Figure 20. The device characteristics of Comparative Device 4 and Device 5 are shown in Table 7. In Table 7, V on is the on-state voltage, L max is the maximum luminance, CE is the current efficiency, PE is the power efficiency, EQE is the external quantum efficiency, λ EL is the maximum wavelength of emission, FWHM is the full width at half maximum of the emission peak, CIE(x,y) is the CIE chromaticity coordinate measured at 1000 nits, LT95 is the time until the brightness reaches 95% of the initial brightness when continuously driven at 1000 nits, LT90 is the time until the brightness reaches 90% of the initial brightness when continuously driven at 1000 nits, and the driving voltage is 5 mA / cm 2 Here, the values ​​shown in the upper row of the EQE column are, from the left, the maximum EQE value read from Figure 18, 100 cd / m 2 EQE at 1000 cd / m 2 EQE at 10000cd / m 2 The values ​​shown in the lower row are relative values ​​to the maximum EQE. The smaller this relative value, the more suppressed the roll-off. LT90 and LT95 are values ​​measured in the absence of oxygen, and the value in parentheses in the LT95 column is the current density at which the luminance reaches 95% of the initial luminance. Table 7 also lists the PL quantum yield Φ of the thin films shown in Table 2. Ar is also shown.

[0101] [Table 7]

[0102] The degradation of luminescence intensity over time in the absence of oxygen, as shown in Figure 19, reflects the degradation of singlet and triplet excitons in the emitting dopant. As shown in Figure 19, Comparative Device 4, which used a compound in which naphthyl groups were introduced into CzBN (CzBNNa) as the emitting dopant, and Device 5, which used a compound in which pyrenyl groups were introduced into CzBN (CzBNPyr), showed less degradation than Comparative Device 5, which used a compound in which phenyl groups were introduced into CzBN (CzBNPh). Furthermore, between Comparative Device 4 and Device 5, Device 5 using CzBNPyr had a longer lifetime (LT95 and LT90 in Table 7). This confirmed that the introduction of polycyclic aromatic groups into multi-resonance TADF materials improves lifetime, and that the introduction of pyrenyl groups is particularly favorable, even in electroluminescent devices.

[0103] [ka] [Industrial Applicability]

[0104] By introducing polycyclic aromatics into a multiple resonance effect type narrow band luminescent material, triplet excitons can be removed more effectively from the multiple resonance skeleton, resulting in a fluorescent molecule with almost unchanged luminescence properties. According to the present invention, a stable narrow-bandwidth luminescent material with high color purity can be provided, and the stability of a light-emitting device can be improved, so that the present invention has high industrial applicability.

Claims

1. A compound represented by the following general formula (1): General formula (1) M Ｒ -X (In the above formula, M Ｒ represents a partial structure that functions as a light-emitting material utilizing the multiple resonance effect when X is a hydrogen atom, and includes one or more skeletal structures selected from the group consisting of the following structures 2 to 10, 17, and 18, wherein X represents a polycyclic aromatic group including 4 to 6 fused rings, and the fused rings include a pyrene ring in the ring skeleton. 【Chemistry 1】

2. The compound according to claim 1, wherein the polycyclic aromatic group is a group bonded to the 4- to 6-fused ring at an atom constituting the ring skeleton.

3. 3. The compound according to claim 1, wherein the energy difference between the lowest singlet excited state and the lowest triplet state is 0.30 eV or more.

4. The compound according to any one of claims 1 to 3, wherein X is a substituted or unsubstituted pyrenyl group.

5. A light-emitting device comprising a compound according to any one of claims 1 to 4.

6. A method for designing a narrow-bandwidth light-emitting material with improved stability, characterized by substituting one or more hydrogen atoms constituting a light-emitting material molecule using a multiple resonance effect with a polycyclic aromatic group containing 4 to 6 fused rings (here, the ring skeleton constituting the aromatic group may contain a heteroatom), wherein the light-emitting material molecule comprises one or more skeleton structures selected from the group consisting of the following structures 2 to 10, 17, and 18, and the fused ring contained in the polycyclic aromatic group contains a pyrene ring in the ring skeleton. 【Chemistry 2】

7. A design method for a narrow-bandwidth light-emitting material with improved stability (here, the ring skeleton constituting the aromatic group may contain a heteroatom), the design method comprising: assuming two or more types of molecules in which one or more hydrogen atoms constituting a light-emitting material molecule using a multiple resonance effect are substituted with a polycyclic aromatic group containing 4 to 6 fused rings; and evaluating the two or more assumed molecules by calculation to select an optimal molecule; wherein the light-emitting material molecule comprises one or more skeleton structures selected from the group consisting of the following structures 2 to 10, 17, and 18, and the fused ring contained in the polycyclic aromatic group contains a pyrene ring in the ring skeleton. 【Transformation 3】

8. A program for implementing the design method according to claim 6 or 7.

9. A method for producing a narrow-bandwidth light-emitting material with improved stability, characterized by substituting one or more hydrogen atoms constituting a light-emitting material molecule using a multiple resonance effect with a polycyclic aromatic group containing 4 to 6 fused rings (here, the ring skeleton constituting the aromatic group may contain a heteroatom), wherein the light-emitting material molecule comprises one or more skeleton structures selected from the group consisting of the following structures 2 to 10, 17, and 18, and the fused ring contained in the polycyclic aromatic group comprises a pyrene ring in the ring skeleton. 【Chemistry 4】

Images