Regulating Intermolecular Packing Mode by Tetrahedral Core for Efficient Solution‐Processable Blue Emitters

Abstract Suppressing exciton quenching of blue thermally activated delayed fluorescence (TADF) emitters is key for high‐efficiency solution‐processable OLEDs. Herein, this issue is addressed through incorporating a sterically tetrahedral tetraphenylsilicon core with blue TADF unit, tert‐butylcarbazole donor, and benzoylpyridine acceptor. The bulky spatial tetrahedral structure effectively reduces aggregation of TADF units and thus mitigates exciton quenching. Moreover, the intermolecular packing mode can also be optimized by strategically modulating the types of host units, which enables intermolecular through‐space charge transfer (TSCT) channel and accelerate the reverse intersystem crossing rate ( k RISC ). Among the prepared three emitters, 3CzSiPMDTC presents the extended occupancy volume, combined through‐bond charge transfer and TSCT channels, and thus alleviates aggregation‐caused quenching of triplet excitons. Eventually, it exhibits a low non‐radiative decay rate of 1.32 × 10 5 s −1 , a high photoluminescence quantum yield of 79% and an enhanced k RISC of 1.07 × 10 6 s −1 . The doped and non‐doped solution‐processed blue OLEDs based on 3CzSiPMDTC achieve the maximum external quantum efficiencies of 18.3% and 12.9%, respectively, ranking among the top‐tier reported blue emitters. This work demonstrates that simultaneously regulating molecular and aggregated‐state structures via a tetrahedral core enables efficient solution‐processed blue emitters, advancing the development of high‐performance blue OLEDs.