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.