Soosaimanickam Ananthakumar

The surface chemistry of cesium lead halide perovskite nanocrystals has been elaborately studied in recent years and has proved the critical role of carboxylic acids and amines in the formation and stability of the nanocrystals. Specifically, a slight change in the concentration and ratio of the frequently used oleic acid and oleylamine critically influences the resultant phase and physical properties. Thus, understanding the delicate surface of cesium lead halide perovskite nanocrystals mainly relies on chemical bonding and the dynamic ligand environment of these two organic species. In this aspect, this review summarizes experimental findings about the critical role of oleic acid and oleylamine on the nucleation, growth, stability, phase, and morphology of cesium lead halide perovskite nanocrystals and their effect under different circumstances.

Synthesis of cadmium sulphide (CdS) nanocrystals was carried out using hot-injection method through oleylamine as solvent and capping ligand at 220^oC. From the UV-visible absorption spectra, the band gap of the synthesized nanocrystals was estimated as 2.5 eV. X-ray diffraction pattern confirms the presence of wurtzite phase with their characteristic reflections. TEM analysis of the synthesized nanocrystals show that the nanocrystals are having nearly spherical shape with the diameter ⁓5-10 nm. For the comparison, different solvent mixtures were employed to prepare the CdS nanocrystals and the structural and optical results show that the solvents have significant influence on the optical properties of the prepared nanocrystals. The results are discussed in detail.