Designing efficient ligand exchange strategies for the synthesis of stable perovskite nanocrystals

Perovskite nanocrystals are promising candidates for light-emitting diodes due to their excellent photoelectronic properties. However, the stability of perovskite nanocrystal thin films against oxygen, water, UV light, and heat is inadequate when synthesized using traditional hot injection methods, limiting their practical applications in devices such as light-emitting diodes. In this study, we synthesized perovskite nanocrystals with enhanced stability and charge transport properties through in situ ligand exchange using zwitterionic ligands. The perovskite thin film retained 90% of its initial PLQY at 353 K and in ambient conditions (relative humidity 80%). Additionally, after 16 hours of UV 254 irradiation, the perovskite film maintained 80% of its initial PLQY. Highly efficient perovskite QLEDs based on these stable perovskite nanocrystals were also fabricated, achieving a sub-bandgap turn-on voltage and an external quantum efficiency of 23.36%, with an operational lifetime T₅₀ of 1.6