Achievement of High-Performance Nondoped Blue OLEDs Based on AIEgens via Construction of Effective High-Lying Charge-Transfer State

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 ofp-cyano ando-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) (CIEx,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.