Reaction-temperature-dependent shape evolution and optical properties of CsPb(Br/Cl)3 perovskite nanocrystals.

Cesium lead halide perovskites are promising materials for light-emitting diodes (LEDs) due to their tunable band gaps, defect tolerance, and high photoluminescence quantum yields (PLQYs) with narrow emission widths. In particular, mixed-halide CsPb(Br/Cl)3 nanocrystals (NCs) are promising candidates for true-blue light emission. The properties of these materials are influenced by both their size and composition; however, research on the synthesis conditions related to these two factors is limited. In this work, we systematically investigate the influence of reaction temperature on the morphology and optical properties of CsPb(Br/Cl)3 NCs synthesized via a hot-injection method. Morphological transformations from nanoplatelets to monodisperse cubic NCs were observed with an increase in reaction temperature. Optical spectroscopy shows a progressive red shift in emission, accompanied by a reduction in the peak linewidth and the Stokes shift. Bandgap energies determined from Tauc analysis strongly correlate with the size of cubic-shaped particles, as described by the Brus quantum confinement model. These results demonstrate that reaction temperature provides an effective strategy for controlling dimensionality, morphology, and excitonic properties of CsPb(Br/Cl)3 NCs, offering a simple pathway to tailor blue-emitting perovskite nanomaterials for optoelectronic applications.