High Efficiency and Stable Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence Emitter

High efficiency, stable organic light-emitting diodes (OLEDs) based on 2-pheyl-4'-carbazole-9-H-Thioxanthen-9-one-10,10-dioxide (TXO-PhCz) with different doping concentration are constructed. The stability of the encapsulated devices are investigated in detail. The devices with the 10 wt% doped TXO-PhCz emitter layer (EML) show the best performance with a current efficiency of 52.1 cd/A, a power efficiency of 32.7 lm/W, and an external quantum efficiency (EQE) of 17.7%. The devices based on the 10 wt%-doped TXO-PhCz EML show the best operational stability with a half-life time (LT50) of 80 h, which is 8 h longer than that of the reference devices based on fac-tris(2-phenylpyridinato)iridium(III) (Ir(ppy)_3). These indicate excellent stability of TXO-PhCz for redox and oxidation processes under electrical excitation and TXO-PhCz can be potentially used as the emitters for OLEDs with high efficiency and excellent stability. The high-performance device based on TXO-PhCz with high stability can be further improved by the optimization of the encapsulation technology and the development of a new host for TXO-PhCz.