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

Abstract

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 ∼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.