Reduced graphene oxide (rGO)-CsSnI3 nanocomposites: A cost-effective technique to improve the structural and optical properties for optoelectronic device applications

The lead-free halide-based perovskite is widely used because of its superior performance, long carrier diffusion length, narrow band emission, and tuneable bandgap. However, improvement of carrier lifetime and stability is the prime challenge for such perovskites. Therefore, reduced graphene oxide (rGO) is used as an additive material in CsSnI3 pristine perovskites to improve the optical, electronic, and structural properties. In this work, we synthesized the perovskite and rGO nanocomposite using the hot injection technique. We have performed photoluminescence (PL), ultraviolet spectroscopy (UV-Vis), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) to understand the effect of rGO in Perovskite. In PL, a peak is found at ~ 782 nm for as-synthesis perovskite and after the 1% rGO incorporation, the peak is shifted towards the higher wavelength around ~ 811 nm. In XRD, the multiple diffraction peaks for the CsSnI3 perovskite and rGO nanocomposite are observed at 27.46°, 39.41°, 48.48°, 56.93°, and 64.38°, which originated from the indexing planes of (221), (112), (540), (082), and (053), respectively. The dominant peak (221) shifts towards the higher angle (0.07°) after 5% rGO incorporation. The UV-Vis spectroscopy confirms bandgap reduction after rGO incorporation in pristine CsSnI3 perovskite. The bandgaps of 1.64 eV and 1.56 eV are calculated from Tauc’s plot for CsSnI3 and rGO/CsSnI3 nanocomposite, respectively. Therefore, the rGO incorporation in the pristine CsSnI3 perovskite demonstrates highly promising properties, which opens the gateway towards the improvement of optoelectronics device performance.