An effective strategy to boost 3D perovskite light-emitting diode performance via solvent mixing strategy

In this study, we demonstrate a simple method to achieve highly efficient perovskite light-emitting diode (PeLED) via casting the neat methylammonium bromide (MABr) in mixed solvents with different solubility on top of the perovskite layer for bulk recrystallization and interfacial passivation. The perovskite crystals reacting with MABr can be reformed orderly and stereoscopically with a reduced domain size on surface and reduced grain boundaries in bulk, which is advantageous to obtain strong fluorescence intensity and long exciton lifetime. The remaining MABr molecule that does not react with perovskite can attach on the recrystallized perovskite surface to develop a passivation layer, which can effectively eliminate exciton interface recombination in PeLEDs. The optimized PeLED exhibits a maximum luminance of 27692.2 cd m−2, which is more than 11 times and 2 times higher than the control device without MABr treatment and the control device with high MABr molar ratio and thin perovskite film thickness, respectively. This work provides an effective strategy to boost PeLED performance by optimizing mixed solvent ratios and concentrations of organic ligand MABr without changing the thickness of the emitting layer.