Charge Environment and Perovskite Crystallization Regulation Interface Engineering with Molecular Bridge for Efficient Deep-Blue (448 nm) Light-Emitting Diodes

Deep-blue perovskite light-emitting diodes (PeLEDs) based on reduced-dimensional perovskites (RDPs) have suffered from unbalanced charge injections and uncontrolled crystallization kinetics processes, impeding the realization of high-performance PeLEDs. In this work, an interfacial chemical molecular bridge was implemented between the RDP and poly(9-vinylcarbazole) (PVK) hole transporting layer to engineer the interfacial electrical environment. The results reveal that the bridging molecule exhibits a strong interface reaction with PVK, facilitating hole injection and improving energy level alignment. Simultaneously, the molecular bridge regulates RDP crystallization dynamics, which inhibits the formation of halide clusters as well as small-<i>n</i> phases and improves defect renovation at the buried interface. As a result, the optimized RDP films exhibit a high photoluminescence quantum yield (PLQY) of 71.69% at 447 nm. The modified PeLEDs deliver an external quantum efficiency (EQE) of 4.48%, along with spectrally stable deep-blue electroluminescence.