Design,Synthesis And Application Of Organic Electroluminescent Materials Containing Carbazole Group

Technological innovation in organic light-emitting diodes（OLEDs）is currently mainstream in the field of displays and lighting.The development of high-efficiency organic light-emitting materials is a key technology for OLEDs.The aggregation-caused quenching（ACQ）phenomenon of traditional organic light-emitting materials seriously affects the device performance.The advent of aggregation-induced emission（AIE）materials has fundamentally solved the ACQ problem,and further developed organic optoelectronic materials.In addition,phosphorescent materials that have been commercialized contain heavy metals,although they can theoretically achieve 100%exciton utilization,but such materials have the defects of high cost and incomplete color.In order to achieve the effective use of triplet excitons of low-cost pure organic small molecule materials,scientists have developed several mechanisms for the effective use of triplet excitons,such as thermally-activated delayed fluorescence,triplet-triplet annihilation,and hot excitons.In this study,two organic luminescent materials were designed and synthesized by combining AIE and thermally-activated delayed fluorescence,AIE and hot excitons,and their structure was determined and their properties studied.The main research contents of the paper are as follows:（1）In the second chapter,an organic fluorescent material containing an asymmetric structure with AIE and TADF properties was synthesized with sulfone group as electron acceptor and phenoxazine as electron group p-CZ-BP-PXZ.P-CZ-BP-PXZ exhibits a smallΔE_ST value,indicating that the compound can undergo a reverse intersystem crossing process.In addition,the emission peak of non-doped OLED prepared with p-CZ-BP-PXZ as light-emitting layer was located at 523 nm with green emission,and its V_on,L_max,CE_max,PE_max and EQE_max were 2.6 V,3318 cd m^-2,6.96 cd A^-1,7.78 lm W^-1 and 2.40%,respectively.（2）In the third chapter,an organic fluorescent material containing an asymmetric structure with AIE and hot excitons properties was synthesized with cyanogen group as electron acceptor and carbazole as electron group p-CN-CZ.Studies of photophysical,ground state and excited state properties show that p-CN-CZ is a typical hot exciton material,and it exhibits significant fluorescence enhancement in the aggregated state.The emission peak of the non-doped OLED prepared with p-CN-CZ as the light-emitting layer material was 592 nm,the CIE coordinates were（0.53,0.45）with yellow emission,and its V_on,L_max,CE_max,PE_max and EQE_max were 4.3 V,1771 cd m^-2,1.84 cd A^-1,1.2 lm W^-1 and 0.7%,respectively.