Suppressing Ion Migration Enables Stable Perovskite Light‐Emitting Diodes with All‐Inorganic Strategy

Stability issue is one of the major concerns that limit emergent perovskite light-emitting diodes (PeLEDs) techniques. Generally, ion migration is considered as the most important origin of PeLEDs degradation. In this work, an all-inorganic device architecture, LiF/perovskite/LiF/ZnS/ZnSe, is proposed to address this imperative problem. The inorganic (Cs1-xRbx)(1-)(y)K(y)PbBr(3)perovskite is optimized with achieving a photoluminescence quantum yield of 67%. Depth profile analysis of X-ray photoelectron spectroscopy indicates that the LiF/perovskite/LiF structure and the ZnS/ZnSe cascade electron transport layers significantly suppress the electric-field-induced ion migrations of the perovskite layers, and impede the diffusion of metallic atoms from cathode into perovskites. The as-prepared PeLEDs display excellent shelf stability (maintaining 90% of the initial external quantum efficiency [EQE] after 264 h) and operational stability (half-lifetime of about 255 h at an initial luminance of 120 cd m(-2)). The devices also exhibit a maximum brightness of 15 6155 cd m(-2)and an EQE of 11.05%.