Design,Synthesis And Photoelectric Properties Of Red Fluorescent Materials Based On Phenazine As A Core

In this thesis,we address the existing problems of red emitters by constructing molecules from the perspective of the combination of a donor and an acceptor.The rigid and strong donor unit phenazine is introduced into the skeleton of the molecule,and the idea of constructing highly efficient red materials is explored through both the replacement of the acceptor unit and the modification technology of the donor unit.Details of the study are as follows:1.Two D-A-D type molecules,TPAC2 and TPANZC2,were constructed using phenoxazine and triphenylamine as donors and benzothiadiazole and naphthothiadiazole as acceptors,combined with theoretical calculations to investigate the differences in the thermal,electrical and photophysical as well as electroluminescent properties of both molecules.It has been found that TPAC2 exhibits aggregation-induced emission(AIE)behaviour.A hybridized local charge transfer(HLCT)state was found for the lowest excited state(S₁)of both molecules.After fabricating the material into a device,the device with TPAC2 as the emitting layer exhibited deep red emission at 677 nm with a maximum external quantum efficiency(EQE)of 2.0%.The device fabricated with TPANZC2 achieved near-infrared emission at 754 nm,with a maximum EQE of 1.3%.The exciton utilization rates for both devices were calculated to be 26%and 54%and both materials were analysed to be hot exciton materials.And the devices fabricated by TPAC2 exhibited a controlled behaviour of device EQE trends with different electron transport layers.2.Based on the TPAC2 molecular skeleton,the molecule TPAPH is constructed by replacing the ethyl group with a benzene ring to achieve greater rigidity.At the same time,TPAPHOC2 was constructed by adding an electron-giving group,ethoxy,in the opposite position of the benzene ring to enhance the donor capacity.The luminescence behaviour of two D-A-D molecules with different donor capabilities was investigated.The results show that the phenyl ring-substituted TPAPH has superior luminescence properties,with a fluorescence quantum efficiency of 51%in the thin film state,and the non-doped device achieved red emission at 645 nm with an EQE of 3.8%.TPAPHOC2 achieved deep red emission at 671 nm with an EQE of 1.7%,and both materials were analysed as hot exciton materials.With the introduction of solution processing,the maximum EQE of the undoped device was further increased to 5.2%and 2.8%.