Electrospun Lead-Free All-Inorganic Double Perovskite Nanofibers for Photovoltaic and Optoelectronic Applications

Organic–inorganic hybrid perovskite compounds are currently the archetypal materials for high performance photovoltaic (PV) and optoelectronic devices. However, the remaining bottlenecks preventing their large-scale production are their environmental/thermal instability and lead toxicity. Herein, we demonstrate a novel approach to synthesize single-phase electrospun Cs2SnIxCl6–x double perovskites with varying halide content (I, Cl, or mixed I/Cl) as active materials for potential application in perovskite solar cells (PSCs). The X-ray photoelectron spectroscopy and Raman spectroscopy analyses indicated the in situ formation of graphene oxide (GO) during the annealing process. The GO layer was found to enhance the optical properties and thermal stability of the fabricated perovskites even at high Cl content. Moreover, the presence of GO as an insulating layer significantly decreases the bandgap energy of the resulting perovskites. The perovskites with a mix iodide and chloride ions showed significantly improved optical properties with higher photoluminescence (PL) intensity than that of pure chloride or iodide counterparts. Moreover, the compound with low chloride content showed superior thermal stability to those reported in the literature. Therefore, the application of the electrospinning technique is a useful strategy to in situ incorporate GO in lead-free perovskite matrix for potential photovoltaic and optoelectronic applications.