Interface Engineering for High‐Efficiency Perovskite Light‐Emitting Diode Through Poly(Vinyl Pyrrolidone) (PVP) Modification

ABSTRACT The performance of a perovskite light‐emitting diode (PeLED) is strongly dependent on the perovskite film quality. Among them, the buried interface plays a critical role in the crystallization dynamics of perovskite, directly determining the film morphology and optical properties. Herein, we demonstrate the buried interface engineering to regulate the crystallization kinetics of quasi‐2D perovskite film by inserting a poly(vinyl pyrrolidone) (PVP) modification layer between the hole transport layer and perovskite film. The strategy enhances the surface wettability of the hole transport layer, facilitating the uniform coverage of perovskite. Meanwhile, the carboxyl groups in PVP can interact with undercoordinated Pb ions in perovskite to increase the crystallization sites, thereby effectively passivating defects, regulating phase distribution, and suppressing the formation of low‐dimensional phases. Ultimately, a green PeLED treated with PVP modification layer has achieved a high external quantum efficiency of 24.2%, representing an 87% enhancement. Our results highlight the potential of interface engineering based on functional group interactions as an innovation strategy, enabling significant advances in PeLED efficiency.