Tetraoctylammonium bromide-passivated CsPbI3−xBrx perovskite nanoparticles with improved stability for efficient red light-emitting diodes.

• A ligand-exchange reaction using TOAB was present for stable CsPbI 3−x Br x quantum dots. • TOAB-passivated QDs showed environmental resistance, such as, moisture, light, and heat. • TOAB-passivated devices exhibited a maximum luminescence of 1345 cd/m2 and a maximum external quantum efficiency of 11.7%. In this study, we demonstrate a ligand-exchange reaction using tetraoctylammonium bromide (TOAB) salts for the as-synthesized CsPbI 3 perovskite nanoparticles (NPs) to ensure NPs with stable and improved device performance. TOAB passivation provides a negatively polarized halide-rich surface, higher steric hindrance, and a small amount of Br− anions in the NP lattice to significantly improve the NP stability. The red NP-based light-emitting diodes (NpLEDs) based on TOAB-passivated NPs also exhibited excellent performance because of shorter ligands and stable NPs, with a maximum luminescence of 1345 cd/m2 and a maximum external quantum efficiency of 11.7%. [ABSTRACT FROM AUTHOR]