Enhanced Efficiency and Stability of Quasi‐2D Perovskite Light‐Emitting Diodes with Crosslinkable Alkenyl Amine Cations

Abstract Low‐dimensional perovskites formed with the assistance of organic cations as interlayers have been widely used to fabricate high‐performance light‐emitting diode devices, attributing to their dielectric and quantum‐confinement effects and rapid energy transfer process. However, ion migration at perovskite grain boundaries and the dissociation of ligands induced by the “van der Waals” gaps between large organic cations are disadvantageous to the stability of perovskite light‐emitting diodes. Here, crosslinkable 3‐butenylamine hydrochloride is introduced in quasi‐2D perovskites that will crosslink at the grain boundaries and between layered perovskites upon thermal annealing, which suppresses ion migration, reduces interlayer space, and passivates defects. The optimized device exhibits enhanced maximum luminance of 20 177 cd m⁻², current efficiency of 17.5 cd A⁻¹, external quantum efficiency of 5.2%, and 1.6 times increment of T₅₀ lifetime. The organic cation crosslinking strategy is therefore a promising approach to enhance the efficiency as well as stability of layered perovskite devices.