Long-term optical and morphological stability of CsPbBr3 nanocrystal-based films

All-inorganic lead halide perovskite nanocrystals exhibit excellent optical properties, which make them promising for optoelectronic devices. However, the insulating organic ligands at the nanocrystals' surface represent a major issue in their effective application in devices. To decrease the effect of the ligands on carrier transport in perovskite nanocrystal-based films, several post-synthesis treatment methods have been reported, but in most of the cases the nanocrystals tend to degrade over long term storage. To address these concerns, herein we develop a novel surface treatment procedure based on the combination of ammonium thiocyanate and benzoyl bromide for CsPbBr3 nanocrystals. The morphological, optical and structural characterizations were carried out to investigate the evolution of both as-prepared and surface-treated nanocrystals in spin-coated films, over ageing under ambient conditions. It was found that films based on the treated nanocrystals present higher stability, providing a promising path for fabricating optoelectronic devices based on these materials.