Synthesis and optoelectronic characterizations of cesium tin chloride perovskite nanocrystals

Abstract

In this investigation, thermally stable cubic phase cesium tin chloride (CsSnCl3) perovskite nanocrystals were successfully synthesized with a promising surface morphology by adopting a rapid hot-injection technique. The good crystalline quality of these cubic-shaped nanocrystals was confirmed by high-resolution transmission electron microscopy imaging. The binding of organic ligands on the surface of CsSnCl3 was identified and characterized by the nuclear magnetic resonance spectroscopy. The UV-visible spectroscopy ensured that CsSnCl3 nanocrystals have a direct band gap of ~2.98 eV, which was further confirmed by photoluminescence spectroscopy. The band edge positions calculated using the Mulliken electronegativity approach predicted the potential photocatalytic capability of the as-prepared nanocrystals, which was then experimentally corroborated by the photodegradation of rhodamine-B dye under both visible and UV-visible irradiation. By employing experimental parameters, the electronic band structure, charge carrier effective masses etc. of CsSnCl3 nanocrystals were calculated within the generalized gradient approximation (GGA) and GGA+U methods. The theoretical calculation demonstrated a 90% accurate estimation of experimentally observed optical band gap when Ueff = 6 eV was considered. The ratio of the effective masses of the hole and electron expressed as D= m_h^*/m_e^* was also calculated for Ueff = 6 eV. Based on this theoretical calculation and experimental observation, it is assumed that a D value of either much smaller or larger than 1 is the indication of the low recombination rate of the photogenerated electron-hole pairs and the photocatalytic efficiency of a photocatalyst. This comprehensive investigation might be helpful for the large-scale synthesis of thermally stable cubic CsSnCl3 nanocrystals and also for a greater understanding of their potential in photocatalytic and optoelectronic applications.