Ostwald ripening inhibition by a bipolar ligand achieves long-term-reaction and scalable synthesis of ultra-stable CsPbX3 perovskite quantum dots towards LEDs

All-inorganic perovskite quantum dots (PeQDs) hold immense potential for use in light-emitting diodes (LEDs) due to their excellent optoelectronic properties. However, the scalable synthesis and poor stability have severely hindered their application. Here, we solved both the two issues with “one stone”, namely a bipolar ligand 3-(N,N-dimethyloctadecylammonio) propane sulfonate (ASC18). ASC18 contains a positively charged quaternary ammonium group and a negatively charged sulfonic group, which enables for long-term reaction and gram-level synthesis of PeQDs with outstanding morphology, crystallinity, and optical properties. Density functional theory calculations and experimental studies show that these merits arise from the inhibition of Ostwald ripening by ASC18 due to their simultaneous interaction with undercoordinated Br – and Pb 2+ via a bidentate binding mode. Furthermore, ASC18 capped PeQDs present significantly improved stabilities against air, UV irradiation, heat, and polar solvent. Finally, both electroluminescent LEDs and down-conversion white LEDs fabricated with our PeQDs show significant operational stability. This presents a trustworthy avenue to obtain high-quality PeQDs for their practical applications.