Achievement of High‐Performance Nondoped Blue OLEDs Based on AIEgens via Construction of Effective High‐Lying Charge‐Transfer State
Han Zhang, Aisen Li, Ganggang Li, Baoxi Li, Zhiming Wang, Shuping Xu, Weiqing Xu, Ben Zhong Tang
Abstract
Abstract There remains an urgent demand for high‐quality blue luminogens that can simultaneously achieve high photoluminescence quantum yield (PLQY) in film and high exciton utilization efficiency (EUE) in the electroluminescence (EL) process. In this study, a referable molecular design strategy is developed for blue luminogens via constructing low‐lying locally excited (LE) state with an aggregation‐induced emission (AIE) characteristic and high‐lying charge‐transfer (CT) state for the effective triplet‐to‐singlet conversion channel. 2TriPE‐BPI‐MCN with the insertion of p ‐cyano and o ‐methyl groups is designed to compare with its matrix framework (2TriPE‐BPI). They have analogous properties of the lowest singlet (S 1 ) states with blue emission and free of concentration quenching in film; however, 2TriPE‐BPI‐MCN exhibits unusual response for hydrostatic pressure owing to its S 2 state CT characteristics. Therefore, 2TriPE‐BPI‐MCN can harness more electrogenerated excitons than 2TriPE‐BPI, resulting in a better EL performance in nondoped blue organic light‐emitting diodes (OLEDs) (CIE x,y = 0.153, 0.147) with high external quantum efficiency of 4.6% and negligible efficiency roll‐off. These findings could open a feasible avenue to develop high‐quality blue luminogens for high‐performance nondoped blue OLEDs.