Asymmetric Thermally Activated Delayed Fluorescence Materials Rendering High-performance OLEDs Through both Thermal Evaporation and Solution-processing

Exploring high-efficiency thermally activated delayed fluorescence(TADF)materials is of great importance regarding to organic light-emitting diode(OLED).Herein,we present a design strategy for developing asymmetric TADF materials based on a diphenyl sulfone-phenoxazine structure,resulting in efficient TADF emitters(CzPXZ and t-CzPXZ)with aggregation-induced emission properties,while t-CzPXZ is modified with tert-butyl groups.The two compounds exhibit high solid-state luminescence,efficient TADF,and significantly impressive device performances by both thermal evaporation and solution processing.For an instance,CzPXZ and t-CzPXZ enable the thermally-evaporated OLEDs with high external quantum efficiencies(EQEs)of over 20%.Meanwhile,t-CzPXZ allows the solution-processed device with a high EQE of 16.3%with low-efficiency roll-off,attributing to the enhanced molecular solubility and suppressed excitons quenching through tert-butyl modification on t-CzPXZ.The results reveal that the proposed asymmetric structure is a promising approach for developing high-efficiency TADF materials and OLEDs.