KR-102964727-B1 - Compounds, light-emitting materials, and light-emitting devices

Abstract

Compounds represented by the following general formula are useful as luminescent materials. Two of R1 to R5 are aromatic hydrocarbon univalent groups or aromatic heterounivalent groups containing a nitrogen atom, three of R1 to R5 are donor groups, and at least one of them is a carbazole-9-yl group formed by the condensation of a benzofuran ring.

Inventors

• 후지사와 가오리
• 조 용주
• 스즈키 요시타케
• 가키조에 하야토
• 이나다 유
• 양 유석

Assignees

• 가부시키가이샤 큐럭스

Dates

Publication Date

20260513

Application Date

20210610

Priority Date

20200611

Claims (16)

1. A compound represented by the following general formula (1). [In general formula (1), Two of R1 to R5 each represent an aromatic hydrocarbon group that may be substituted with one or more selected from deuterium atoms, alkyl groups, aryl groups, alkoxy groups, and alkylthio groups, and Among R1 to R5 , the other three are donor groups, and each of the three donor groups independently represents a carbazole-9-yl group or a carbazole-9-yl group condensed with a benzofuran ring, and the three donor groups are not all the same, and at least one of the three donor groups is a carbazole-9-yl group condensed with a benzofuran ring. The carbazole-9-yl group and the carbazole-9-yl group condensed with a benzofuran ring may each independently be substituted with one or more groups selected from deuterium atoms, alkyl groups, aryl groups, and diarylamino groups.
2. In claim 1, A compound in which R1 , R2 , and R4 are each independently donor groups.
3. In claim 1, A compound in which R1 , R3 , and R4 are each independently donor groups.
4. In claim 1, A compound in which two of the three donor groups are identical.
5. In claim 1, A compound having a structure in which a benzofuran ring is condensed into a carbazole-9-yl group, wherein a benzofuran ring is directly condensed into one of the benzene rings constituting the carbazole-9-yl group.
6. In claim 5, A compound in which the carbazole-9-yl group formed by the condensation of the above benzofuran ring has any one of the following structures. [In each of the above structures, hydrogen atoms may be substituted.]
7. In claim 5, A compound in which two of R1 to R5 are carbazole-9-yl groups formed by the condensation of the above benzofuran ring.
8. In claim 7, A compound in which the carbazole-9-yl group formed by the condensation of the two benzofuran rings is identical to each other.
9. In claim 5, A compound in which only one of R1 to R5 is a carbazole-9-yl group formed by the condensation of the above benzofuran ring.
10. delete
11. delete
12. In claim 1, Among R 1 to R 5 , the above two are identical compounds.
13. A luminescent material comprising a compound described in any one of claims 1 to 9 and claim 12.
14. A light-emitting device characterized by comprising a compound described in any one of claims 1 to 9 and claim 12.
15. In claim 14, A light-emitting element having a light-emitting layer, wherein the light-emitting layer comprises the compound and a host material.
16. In claim 14, A light-emitting element having a light-emitting layer, wherein the light-emitting layer comprises the compound and the light-emitting material, and emits light from the light-emitting material.

Description

Compounds, light-emitting materials, and light-emitting devices The present invention relates to a compound useful as a light-emitting material and a light-emitting device using the same. Research is actively being conducted to increase the luminous efficiency of light-emitting devices such as organic electroluminescent devices (organic EL devices). In particular, various studies have been carried out to increase luminous efficiency by newly developing and combining electron transport materials, hole transport materials, and light-emitting materials that constitute organic electroluminescent devices. Among these, research on organic electroluminescent devices using delayed fluorescence materials can also be seen. Delayed fluorescence materials are materials that emit fluorescence when returning from the excited singlet state to the ground state after generating an inverse transition from the excited triplet state to the excited singlet state while in an excited state. Since fluorescence produced by this pathway is observed later than fluorescence from the excited singlet state generated directly from the ground state (normal fluorescence), it is called delayed fluorescence. Here, for example, when a luminescent compound is excited by the injection of a carrier, the probability of generating the excited singlet state and the excited triplet state is statistically 25%:75%, so there is a limit to the improvement of luminescence efficiency using only fluorescence from the directly generated excited singlet state. On the other hand, in delayed fluorescence materials, not only the excited singlet state but also the excited triplet state can be utilized for fluorescence emission through the aforementioned inverse transition pathway, so a higher luminescence efficiency is obtained compared to conventional fluorescence materials. Since this principle became clear, various delayed fluorescence materials have been discovered through various studies. However, materials that emit delayed fluorescence are not necessarily useful as immediate luminescent materials. Among delayed fluorescence materials, some are relatively resistant to reverse crossover and have a long lifetime of delayed fluorescence. Furthermore, some exhibit a decrease in luminescence efficiency due to exciton accumulation in high current density regions, or rapidly degrade if operated for a long time. Consequently, the reality is that there are many delayed fluorescence materials that have room for improvement in terms of practicality. For this reason, it has been pointed out that there are challenges even with benzonitrile-based compounds known as delayed fluorescence materials. For example, 2CzPN having the structure below is a material that emits delayed fluorescence, but it faces the challenge of having low luminescence efficiency and a significant decrease in luminescence efficiency in high current density regions (see Non-Patent Literature 1). [Chemical Formula 1] Figure 1 is a schematic cross-sectional view showing an example of the layer configuration of an organic electroluminescent device. The contents of the present invention will be described in detail below. The description of the constituent requirements described below may be based on representative embodiments or specific examples of the present invention, but the present invention is not limited to such embodiments or specific examples. Furthermore, numerical ranges indicated by "~" in this specification refer to a range that includes the values described before and after "~" as lower and upper limits. Also, the isotopes of hydrogen atoms present in the molecule of the compound used in the present invention are not particularly limited; for example, all hydrogen atoms in the molecule may be 1H , or some or all may be 2H (Deuterium D). [Compounds represented by general formula (1)] [Chemical Formula 4] Two of R1 to R5 in general formula (1) each independently represent a substituted or unsubstituted aromatic hydrocarbon group, or a substituted or unsubstituted aromatic complex group containing a nitrogen atom as a ring skeleton constituent atom. In the present invention, the term "aromatic hydrocarbon group" refers to a group in which the bonded ring (one ring) is an aromatic hydrocarbon ring. For example, it includes a phenyl group bonded to one carbon atom constituting the ring skeleton of a benzene ring. The hydrogen atoms constituting the bonded aromatic hydrocarbon ring may be substituted. Furthermore, one or more rings may be condensed to the bonded aromatic hydrocarbon ring. Additionally, another ring may be condensed to the condensed ring. Examples of condensed rings include aromatic hydrocarbon rings, aromatic heterocyclic rings, aliphatic hydrocarbon rings, and aliphatic heterocyclic rings. Examples of aromatic hydrocarbon rings include benzene rings. Examples of aromatic heterocyclic rings include pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, triazine rin