Organic light-emitting diode (OLED) display technology has many excellent properties such as high brightness, low energy consumption, fast response, flexibility, etc., and has gradually replaced liquid crystal display (LCD) and become the mainstream flat panel display technology of the next generation. The luminescent layer based on the main object structure is the core component of OLED, and the development of the subject material is relatively slow compared with the rapid development of the guest luminescent material and its structural diversity.
Therefore, it is of great significance for the further development and application of the development of the main material with novel structure and excellent performance for the preparation of high-performance OLED.
The team of Professor You Jinsong and Associate Researcher Bin Zhengyang of Sichuan University is committed to using CH activation strategy to construct new materials for OLED with non-traditional structures and break through their optoelectronic properties. Recently, Professor You Jinsong and Associate Researcher Bin Zhengyang further constructed a series of new bulk materials of the dibenzocyclox heptanoheptone (EtBP) class with a seven-membered ring receptor structure through the cross-oxidation CH/CH coupling reaction of benzoic acid and styrene, and successfully used to prepare red, green and blue phosphorescent OLED devices with high efficiency and low efficiency roll-off, providing a new idea for the selection of main materials in commercial phosphorescent OLED devices.
The flexible ethyl-linked dibenzocyclic heptanone receptor developed in this work not only has the rotationality (flexibility) of the non-cyclic structure, which can reduce the quenching of excitons caused by tight accumulation between molecules, but also has the rigidity of the cyclic structure, which can inhibit the non-radiative transition caused by excessive rotation within the molecule. Bipolar principal materials are prepared by being connected to methylcarbazole, which exhibits very balanced carrier transport characteristics and good photophysical and thermal stability, which is the key to achieving high and inefficient roll-off OLED devices.
In addition, the use of C–H bond activation strategy to construct OLED materials shows unique advantages over traditional methods: (1) the reaction substrate does not need to be preactivated, which can avoid the challenges brought by the substrate preactivation process; (2) the functional groups are more tolerant, and many reactions can tolerate carboxyl, hydroxyl, amino and even halogen atoms, and these reactive functional groups provide convenience for further derivation; (3) In particular, the guide groups are mostly power-deficient groups, which can be easily derived into electron receptor units in the OLED material, complementing each other. Kill two birds with one stone. These advantages are conducive to generating new models for constructing OLED molecules different from traditional methods, thereby breaking through the bottleneck of OLED material structure and performance.
The study was published in an angladte Chemie International Edition under the title "Structurally Nontraditional Bipolar Hosts for RGB Phosphorescent OLEDs: Boosted by a "Butterfly-Shaped" Medium-Ring Acceptor." Sichuan University is the first unit, Professor You Jinsong and Associate Researcher Bin Zhengyang of the School of Chemistry are the corresponding authors of the paper, and Dr. Ma Weixin is the first author of the paper. Special thanks to the National Natural Science Foundation of China, the Sichuan Provincial Department of Science and Technology, and Sichuan University for their financial support. (Source: Sichuan University)
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