Tuning the structural and photophysical behaviour of non-toxic CsSnCl₃ using reduced graphene oxide for optoelectronic applications

The non-toxic metal halide-based perovskite materials can be a greener alternative to lead-based perovskites because of their stability and high-scale production. Herein, we have tuned the structural and photophysical behaviour of non-toxic halide-based perovskite CsSnCl3 by forming a heterostructure with reduced graphene oxide (rGO) owing to its high carrier mobility and thermal conductivity. The crystal structure of CsSnCl3 and CsSnCl3/rGO heterostructure has been analyzed using the X-ray diffraction (XRD) technique which confirms the formation of a highly crystalline cubic phase. The high absorption behaviour of CsSnCl3 and CsSnCl3/rGO can be clearly seen from the ultraviolet-visible (UV-vis) spectrum. A direct bandgap of 3.24 eV and 3.19 eV has been calculated from the Tauc plot for CsSnCl3 and CsSnCl3/rGO heterostructure respectively. The Photoluminescence (PL) plot shows a high quenching blue shift phenomenon in CsSnCl3/rGO heterostructure as compared to pristine CsSnCl3 material due to the faster separation and transfer of charges from photogenerated electron-hole pairs. Further, the surface morphology of CsSnCl3 and rGO/CsSnCl3 heterostructure has been noticed by utilizing the Field Emission Gun-Scanning Electron Microscope (FEG-SEM) representing a very good morphology of synthesized materials in which CsSnCl3 comprises a granular kind of structure which is spread over the rGO sheet. This study suggests the tenability of structural and optical properties with enhancement in stability of pristine CsSnCl3 by forming heterostructure with rGO for their future utility in highly stable, and efficient photovoltaic and optical devices.