Effective Design Strategy for Thermally Activated Delayed Fluorescence Emitters with Aggregation-Induced emission to Enable Sky-blue OLEDs Achieving EQE Nearly 30%

Pure organic thermally activated delayed fluorescence (TADF) materials hold great promise for efficient organic light-emitting diodes (OLEDs), yet developing high-performing blue TADF materials that integrate short delayed lifetime with aggregation induced emission (AIE) property remains a significant challenge. In this study, we developed three highly-efficient blue TADF emitters (32clCBP, 32clCXT and 32PclCXT) featuring AIE characteristics by integrating rigid π-extended donors with different acceptors. Notably, in the doped 32PclCXT film achieved an exceptionally high photoluminescence quantum efficiency of up to 99% and a short delayed lifetime of 1.4 µs. Furthermore, the fabricated OLEDs based on 32PclCXT exhibited an impressive external quantum efficiency of 29.9% in the sky-blue region, along with low roll-off at high luminance. Therefore, this work establishes a new strategy for developing high-efficiency blue TADF materials and devices.