Lead-free metal–halide perovskite nanocrystals: synthesis and optical properties [Review]

Subject of study. Lead-free perovskite nanocrystals (LFPNCs), their main characteristics, synthesis methods, and optical properties are examined. Aim of study. The aim is to analyze the state-of-the-art research data on the synthesis methods and optical properties of LFPNCs. In addition, the formation processes of LFPNCs, their main synthesis methods, and the dependence of nanocrystal size and photoluminescence quantum yield (PLQY) on synthesis parameters (such as method, temperature, and ligand type) are determined. Main results. The formation of LFPNCs is analyzed based on the LaMer and cluster growth models. According to the research data, the primary methods for preparing these nanocrystals (NCs) are hot-injection and ligand-assisted reprecipitation (LARP). Evidently, the average size of LFPNCs increases with increasing reaction temperature. For NCs synthesized by LARP, increasing the reaction temperature to 100°C leads to a slight decrease in the quantum yield. However, for the NCs prepared by hot-injection, the PLQY remains independent of the temperature. Additionally, using oleic acid as a ligand results in a narrow size distribution of NCs, whereas using a mixture of ligands results in NCs exhibiting the highest PLQY. Practical significance. The literature analysis results show that the LARP method is the most promising for synthesizing LFPNCs owing to its ease of implementation, energy efficiency, and scalability. The LFPNCs produced using this method can be applied as active materials in sensor technologies, photovoltaics, and optoelectronic devices.