Tenability and improvement of the structural, electronic, and optical properties of lead-free CsSnCl3 perovskite by incorporating reduced graphene oxide (rGO) for optoelectronic applications

The lead-free metal halide perovskite materials are a potential candidate for optoelectronics and photovoltaic applications due to their promising and outstanding properties. Herein, we have tuned and improved the structural, electronic, and optical behaviour of the CsSnCl3 perovskite nanomaterial by incorporating reduced graphene oxide (rGO) for solar cell applications. The hot injection method has been used for the synthesis of CsSnCl3 and nanocomposites of CsSnCl3/rGO with varying rGO content (1%, 2%, 3%, 4% and 5%) and further material characterization has been done by using various characterization techniques for improvement of the quality and performance of perovskite solar cells (PSCs). The lead-free halide-based inorganic CsSnX3 (X = Cl, Br, I) perovskite layer and rGO/CsSnCl3 nanocomposite are synthesized by using a cost-effective hot injection method. The crystal structure of the as-prepared CsSnCl3 and rGO nanocomposites has been analyzed by X-ray diffraction (XRD). Ultraviolet-visible spectroscopy (UV-Vis) confirms that both the CsSnCl3 and rGO nanocomposite have a direct bandgap of similar to 3.24 eV and 3.19 eV, respectively. The photoluminescence (PL) confirmed that the rGO nanocomposite shows a high quenching phenomenon as compared to the pristine CsSnCl3 material, and such quenching is possibly due to the faster separation and transfer of charges of photogenerated electron-hole pairs. In PL, a blue shift of 7 nm is observed by incorporating the rGO sheet with CsSnCl3 nanoparticles. Along with this, we have examined the surface morphology of the rGO, CsSnCl3, and rGO/CsSnCl3 nanocomposite materials by field emission gun scanning electron microscopy (FEG-SEM), and it is observed that CsSnCl3 nanoparticles are a granular kind of structure and spread over the rGO sheet. A morphological study has been done for the CsSnCl3 and rGO nanocomposites by using a high-resolution transmission electron microscope (HRTEM), and a study of the selected area electron diffraction (SAED) pattern confirms that high crystallinity has been observed in pure CsSnCl3 compared to the rGO nanocomposites. In the present study, the incorporation of rGO in the lead-free halide-based perovskite absorber layer demonstrates highly promising properties to develop several photovoltaics and optical devices in the near future.