Distinguishing the respective determining factors for spectral broadening and concentration quenching in multiple resonance type TADF emitter systems
Feng Huang, Xiao‐Chun Fan, Ying‐Chun Cheng, Hao Wu, Yi‐Zhong Shi, Jia Yu, Kai Wang, Chun‐Sing Lee, Xiaohong Zhang
Abstract
Multiple resonance (MR) type thermally activated delayed fluorescence (TADF) emitters have attracted much recent attention due to their narrow emission spectra and high photoluminescence quantum yields (PLQYs). Spectral broadening and concentration quenching at high doping concentrations are two issues currently limiting the development of MR-TADF emitters. However, the origins of these have not been fully clarified so far. In this work, by investigating emitters with the same MR cores but peripheral groups of different steric types, we distinguished that the spectral broadening and concentration quenching are mainly caused by excimer formation and triplet exciton annihilation, respectively. This understanding on aggregated behaviors of MR emitters provides new insight for the further development of high-performance MR-TADF emitters with low concentration sensitivities.