Anion Exchange in Cesium Lead Halide Perovskite Nanocrystals via Radiation Chemistry of Halohydrocarbons

Cesium halide lead (CsPbX3) perovskite nanocrystals (NCs) have been extensively studied in recent years for their unique capability of postsynthesis anion exchange, providing facile tunability of band gaps and optical properties. In this work, we demonstrate for the first time a simple approach to the tunable anion exchange of CsPbX3 perovskite NCs via radiation chemistry of inert halohydrocarbons. The anion exchange extents are monitored by shifting of fluorescence emission peaks and ultraviolet-visible absorbance edges and are precisely controlled by tuning the absorbed doses and the adjustable addition of halohydrocarbons. At the same absorbed doses, the anion exchange extents by halohydrocarbons are dependent on the linear attenuation coefficients of halohydrocarbons. Radiation-induced anion exchange can passivate defects in CsPbX3 NCs, resulting in the fluorescence enhancement. The morphology of perovskite NCs almost remains intact after radiation-induced anion exchange.