CN-116283949-B - Blue fluorescent molecule and preparation method and application thereof

Abstract

The application discloses a blue fluorescent molecule, which has a D-pi-A structure, comprises oxadiazole as an acceptor group and phenylcarbazole as a donor group, and takes an aromatic ring with a heat exciton energy level arrangement characteristic as pi bridge to connect the acceptor group and the donor group. The application also provides a preparation method and application of the blue fluorescent molecule. The application takes the aromatic ring with the characteristic of heat exciton energy level arrangement as pi bridge, reasonably regulates and controls the high-energy excitation state of the aromatic ring by introducing the aromatic ring into the receptor, activates the heat exciton channel of the molecule, breaks through the 25% exciton utilization rate limit of the fluorescent material, and further improves the exciton utilization rate.

Inventors

• YING LEI
• YU YUE

Assignees

• 华南协同创新研究院

Dates

Publication Date

20260508

Application Date

20230225

Claims (5)

1. 1. A blue fluorescent molecule is characterized by having a D-pi-A structure, comprising oxadiazole as an acceptor group and phenylcarbazole as a donor group, wherein an aromatic ring with a heat exciton energy level arrangement characteristic is used as pi bridge to connect the acceptor group and the donor group, and the blue fluorescent molecule has one of the following structural formulas M1-M4: 。
2. 2. a method of preparing a blue fluorescent molecule according to claim 1, comprising the steps of: An oxadiazole intermediate having one of the following structural formulas is used: Using a phenylcarbazole intermediate I having one of the following structural formulas: Reacting the phenylcarbazole intermediate I with the bisboronic acid pinacol ester to synthesize a phenylcarbazole intermediate II with one of the following structures: and reacting the phenylcarbazole intermediate II with the oxadiazole intermediate to synthesize the blue fluorescent molecule.
3. 3. Use of the blue fluorescent molecule of claim 1 in a light emitting diode device or an organic electroluminescent device.
4. 4. An organic electroluminescent device comprises an anode, a hole injection layer, a hole transport layer, an organic luminescent layer, an electron transport layer, an electron injection layer and a cathode from bottom to top, wherein the luminescent layer contains the blue fluorescent molecules as defined in claim 1.
5. 5. The organic electroluminescent device of claim 4, wherein the organic luminescent layer is a pure film of blue fluorescent molecules or a composite film doped with a guest.

Description

Blue fluorescent molecule and preparation method and application thereof Technical Field The invention relates to the technical field of organic photoelectric materials, in particular to a blue fluorescent molecule, a preparation method and application thereof. Background Organic LIGHT EMITTING (OLED) is a new generation of display and lighting technology, and has advantages of self-luminescence, abundant material sources, wide color gamut, pure chromaticity, eye protection, flexibility, etc., so that it has been widely paid attention to since commercialization, and has been widely used in the field of full-color flat panel display and lighting. OLED luminescent materials are used as the core of OLED display technology, and are also increasingly stacked with the development of OLEDs. At present, compared with red light and green light OLED materials, blue light OLED materials have a small difference in efficiency and service life, and particularly have high brightness. This severely hampers the development of the OLED industry. The core scientific problem of the OLED luminescent material for realizing high exciton utilization is a triplet excited state, which is limited by spin statistics, 75% of the excited states in the traditional OLED are non-luminous triplet states, and the device efficiency of only utilizing singlet excitons is lower. To solve this problem, thermally-activated delayed fluorescence TADF materials (Nature 2012,492,234-238) based on triplet-opposite-system cross-over (RISC) and TTA fluorescent materials (adv.funct.mater.2013, 23, 739-746) based on triplet annihilation up-conversion have been proposed internationally. TADF materials can utilize triplet excitons through an ultra-fine interaction intersystem crossing process to achieve 100% maximum theoretical Internal Quantum Efficiency (IQE), which is problematic in that deep blue TADF materials are particularly rare and device efficiency roll-off is relatively large. The TTA material reported at present can annihilate two triplet state excitons and then convert the annihilated triplet state excitons into one singlet state exciton, and the principle can improve the utilization rate of the excitons to a certain extent, but the maximum IQE of the device theory is only 62.5%. In contrast, the Maguang institution group proposed a new mechanism "thermal exciton" mechanism that can fully utilize singlet excitons and triplet excitons in 2011, and theoretically, 100% exciton utilization can be achieved. The material is characterized by having a larger T2-T1 energy gap and a smaller T2-S1 energy gap. Since the presence of the large energy gap of T2-T1 hinders the internal switching process (IC) from T2 to T1, the high-energy reverse intersystem crossing process from T2 to S1 is accelerated, thereby achieving high exciton utilization and low efficiency roll-off. However, the efficiency of the currently reported thermoexciton materials is greatly different from that of the synchronous TADF materials, and effective improvement of molecules is needed. In addition to efficiency, device stability at high brightness is also a major bottleneck in current blue OLED materials. The great reason for this is that the carrier mobility of organic semiconductor materials, especially electron mobility, is typically more than 2 orders of magnitude lower than hole mobility, affecting the carrier balance in OLED devices. In addition, low carrier mobility can also cause the device to generate a significant amount of joule heating during operation, further affecting device lifetime. Disclosure of Invention In order to overcome the defects of the prior art, the application aims to provide a blue fluorescent molecule, which takes an aromatic ring with the energy level arrangement characteristic of a thermal exciton as a pi bridge, reasonably regulates and controls the high-energy excitation state of the blue fluorescent molecule by introducing an acceptor, activates a thermal exciton channel of the molecule, breaks through the 25% exciton utilization rate limit of a fluorescent material, and further improves the exciton utilization rate. In order to solve the problems, the technical scheme adopted by the application is as follows: a blue fluorescent molecule has a D-pi-A structure, comprises oxadiazole serving as an acceptor group and phenylcarbazole serving as a donor group, and takes an aromatic ring with a thermal exciton energy level arrangement characteristic as pi bridge to connect the acceptor group and the donor group. In a further preferred embodiment of the present application, the blue fluorescent molecule has one of the following structural formulas or one of the homologs or derivatives substituted by halogen or alkyl groups: wherein Ar represents an aromatic ring pi bridge structure. In a further preferred embodiment of the present application, ar represents one of the following structural formulas or one of the halo, alkyl substituted homologs or derivative