Advancements and Challenges in Synthesizing Colloidal Semiconductor Nanocrystals by Hot-Injection Method

Synthesis of semiconductor nanocrystals through solution-based approaches has turned out huge interest among researchers. Out of other methods, preparation of colloidal semiconductor nanocrystals through hot-injection method is intensively investigated owing to its versatility. Importantly, the structure, shape and size of the nanocrystals can be precisely tuned with respect to the precursors and temperature. This influence a lot on the composition, physical, and chemical properties of the synthesized nanocrystals. Using hot-injection synthesis approach, the nanocrystals are prepared either in aqueous medium or in organic solvents. The acidic or basic nature of surface metal atoms integrate the ligand interaction and hence stability of the nanocrystals in solution is governed. Furthermore, with respect to the reaction time intervals and type of precursors, the absorption and emission spectra of the nanocrystals can be tuned. Diverse range of inorganic nanocrystals such as metallic nanostructures (ex: Ag, Au, Pt, Pd) metal-chalcogenide semiconductor nanocrystals (ex: CdS, ZnS, CdTe, CdSe), metal-oxide nanocrystals (ex: TiO2, CeO2), metal phosphides, metal nitrides and metal halide perovskite nanocrystals (RNH3PbX3 and CsPbX3, where R = alkyl group and X = Cl, Br and I) are prepared using this method and their structural, optical and morphological properties are evaluated. Interesting features such as polytyphism, different phase formation, surface charge and ligand metal interaction are dealt with respect to the reaction conditions. In this view, this chapter discuss about the advancements of hot-injection approach in synthesizing different group semiconductor nanocrystals, challenges and it's future perspectives.