Molecular Interface Reconstruction via Coupled Coordination and Hydrogen‐Bond Interactions for Efficient and Stable Deep‐Red Perovskite Light‐Emitting Diodes

Abstract

All‐inorganic CsPbI 3 perovskites have emerged as promising emitters for deep‐red perovskite light‐emitting diodes (PeLEDs) due to their suitable bandgap and favorable optoelectronic properties. However, achieving highly efficient and stable devices remains challenging, partly due to the complex surface chemistry and interfacial processes in perovskite films. Here, we develop a choline halide molecule to regulate multiple surface‐active sites at the CsPbI 3 interface. Choline halide molecules coordinate with undercoordinated Pb 2+ sites and form hydrogen‐bonded molecules with deprotonated Guanidinium (Gua) species, enabling simultaneous defect passivation and surface stabilization. These interactions promote the formation of low‐dimensional interfacial structures, suppress defect‐mediated non‐radiative recombination, and improve carrier dynamics in CsPbI 3 films. Consequently, choline bromide‐treated CsPbI 3 PeLEDs achieve a peak external quantum efficiency of 24.8% and an operational T 50 lifetime of 88.6 h at 100 mA cm −2 . Moreover, extending this strategy to mixed bromide‐iodide perovskite emitters further yielded a 695 nm deep‐red emission and an operational T 50 lifetime of 119.8 h under a constant current density of 100 mA cm −2 . This work provides insights into molecular regulation of complex perovskite interfaces and offers an approach for developing efficient and stable perovskite optoelectronic devices.