Managing Surface Reconstruction Enables Bright, Stable, and Cost-Performance Perovskite Light-Emitting Diodes

Organic–inorganic hybrid perovskite is emerging as one of the most promising light source technologies. Various interfacial agents have been widely used on perovskite surfaces, aiming to achieve high brightness and stability in perovskite light-emitting diodes (PeLEDs) by eliminating the adverse effects of excess organic halide residues. However, there are only scattered reports available on the unreacted halide distribution, interfacial solvent effect, and cost-performance for surface engineering, calling for low-cost strategies to address these challenges. Here, the distribution of unreacted halide species is visualized and the effect of solvent-dominated surface reconstruction on performance is pointed. Experimental and computational studies reveal that the surface lattice distortion caused by the interaction between solvents and crystals increases non-radiative losses, thus deteriorating device performance. By managing surface reconstruction using a low-cost mixture-solvent surface reconstruction strategy, cost-effective PeLEDs is obtained with a high radiance of 1103.31 W sr −1 m −2 and an extended lifetime of 84.8 h operated at a current density of 100 mA cm −2 , representing the highest brightness for FAPbI 3 -based PeLEDs.