Colloidal Synthesis and Optical Properties of All‐Inorganic Low‐Dimensional Cesium Copper Halide Nanocrystals

Low‐dimensional metal halides have recently attracted extensive attention owing to their unique structure and photoelectric properties. Herein, we report the colloidal synthesis of all‐inorganic low‐dimensional cesium copper halide nanocrystals (NCs) by adopting a hot‐injection approach. Using the same reactants and ligands, but different reaction temperatures, both 1D CsCu₂I₃ nanorods and 0D Cs₃Cu₂I₅ NCs can be prepared. Density functional theory indicates that the reduced dimensionality in 1D CsCu₂I₃ compared to 0D Cs₃Cu₂I₅ makes the excitons more localized, which accounts for the strong emission of 0D Cs₃Cu₂I₅ NCs. Subsequent optical characterization reveals that the highly luminescent, strongly Stokes‐shifted broadband emission of 0D Cs₃Cu₂I₅ NCs arises from the self‐trapped excitons. Our findings not only present a method to control the synthesis of low‐dimensional cesium copper halide nanocrystals but also highlight the potential of 0D Cs₃Cu₂I₅ NCs in optoelectronics.