热活性型延迟荧光材料的研究进展

Research Progress on Thermally Activated Delayed Fluorescent Materials

有机电致发光二极管(OLED)在全彩色平板显示和固态照明领域具有广泛的应用而倍受关注。在电场激发下,单重态激子与三重态激子的比值为1∶3。传统的荧光材料只能利用单重态激子发光,内部量子效率(IQE)最高为25%。热活性型延迟荧光(TADF)材料可将三重态激子反系间跨越(RISC)到单重态能级而发出延迟荧光,理论上内部量子效率可达100%。设计TADF材料的关键在于分子要同时满足高荧光量子产率和小的第一激发单重态与第一激发三重态能级差(ΔEST)。综述了近几年TADF材料的研究进展,重点介绍了TADF材料的设计思想和器件性能。

Organic light-emitting diodes （OLEDs） have attracted significant attention because of their promise for application in full-eolour flat-panel displays and solid-state lighting sources. The ratio of sin- glet excitons to triplet excitons is 1 ： 3 under electrical excitation. The internal quantum efficiency （IQE） of conventional fluorescent OLEDs is limited to 25% because only singlet excitons are available for light emission. Thermally activated delayed fluorescence （TADF） is a promising way to obtain a high nearly 100% IQE by converting triplet excitons up to the singlet state level by the reverse intersystem crossing （RISC）. The key to design TADF materials is to combine a small energy gap （AEsT） between the lowest singlet excited states （St ） and lowest triplet excited states （T1 ） with high photoluminescenee quantum efficiency simultaneously. This review summarizes the recent progress in TADF materials, focusing on the design strategies and device performance.