Influence of Sulfur Precursor Reactivity on Size-Controlled and Optical Properties of CdS Nanocrystals

This study investigates the synthesis of cadmium sulfide (CdS) nanocrystals (NCs) using a hot-injection method, focusing on how sulfur precursor reactivity, controlled by its preparation temperature, influences the final nanomaterial properties. The sulfur precursor was prepared at three temperatures (120, 140, and 180 °C) to modulate its reactivity. Transmission electron microscopy, UV–vis spectroscopy, and photoluminescence spectroscopy were employed to characterize the size, morphology, and optical properties of the resulting CdS NCs. We found a clear correlation between the sulfur precursor preparation temperature and the CdS nanocrystal properties. The precursor prepared at 140 °C resulted in the most homogeneous growth, leading to the smallest size distribution and highest quality NCs, as evidenced by the higher PL intensity. The precursor prepared at 180 °C resulted in a faster growth rate, ultimately leading to larger NCs with inhomogeneous morphologies, while the 120 °C precursor exhibited the slowest growth rate, producing larger particles with a wider size distribution. These findings underscore the significant role of sulfur precursor preparation temperature in controlling the final CdS nanocrystal material properties, offering valuable insights for the tailored synthesis of high-quality CdS nanomaterials for diverse applications.