Facile synthesis and stability enhancement of copper halide perovskite nanocrystals

Lead-free copper-based halides have attracted significant attention for optoelectronic applications due to their excellent photophysical properties, good stability, and environmental friendliness. However, current synthesis methods for copper-based halide nanocrystals either require high-temperature inert protection or rely on insulating long-chain ligands, limiting their practical applications. In this study, we report a facile one-pot room-temperature synthesis of Cs 3 Cu 2 X 5 (X = Cl, Br) and CsCu 2 I 3 nanocrystals using an anti-solvent method. Short-chain propionic acid (PA) is introduced as a surface passivation ligand, significantly enhancing photoluminescence through defect passivation. The PA-coated Cs 3 Cu 2 Cl 5 nanocrystals exhibit good resistance to ethanol but poor stability in water. To improve thermal stability, PMMA encapsulation is employed, with the composite film retaining ∼90% of initial PL intensity at 80∼90 °C and two-thirds at 150 °C. Time-resolved PL decay measurements confirm that both PA coating and PMMA encapsulation prolong the exciton lifetime. This work provides a green and effective strategy for the synthesis and surface engineering of copper-based halide nanocrystals for environmentally friendly optoelectronic applications.