Cesium lead iodide-decorated two-dimensional titanium dioxide/reduced graphene oxide nanofiber composites as photoanodes for inorganic perovskite solar cells

Abstract

In this study, we developed photoanode materials based on inorganic cesium lead iodide (CsPbI3)-decorated two-dimensional titanium dioxide-reduced graphene oxide nanofibers (TiO2/rGO NFs22TiO2/rGO NFs - titanium dioxide-reduced graphene oxide nanofibers.) for perovskite solar cells (PSCs). CsPbI3 was prepared by a two-step solution process and TiO2/rGO NFs were prepared using the electrospinning method. The influence of the as-fabricated TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite on their optical, surface, and morphological properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, ultraviolet–visible–near-infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy analyses. XRD analysis of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite showed a crystalline nature with cubic and anatase crystal faces. The surface morphology of the TiO2 NFs, TiO2/rGO NFs, and CsPbI3 perovskite appeared as a beat-free fiber with a polycrystalline nature. The chemical oxidative states and electronic structures of the electrospun TiO2/rGO NFs were determined by X-ray photoelectron spectroscopy analysis. PSCs device were assembled with TiO2 NFs, TiO2/rGO NFs as photoanode, 2,2′,7,7′-Tetrakis(N,N-di-P-methoxyphenylamine)− 9,9′-spirobifluorene (Spiro–OMeTAD) as hole transport materials, sputtered gold chloride as back electrode (counter electrode). In addition, the CsPbI3 perovskite coated on the electrospun TiO2 and TiO2/rGO NF photoanodes exhibited electrical conductivities of 1.352 × 10−3 and 1.650 × 10−3 S cm−1. Finally, power conversion efficiency of TiO2/rGO NFs (6.38 %) was achieved, which was significantly higher than that of conventional TiO2 NFs (5.54 %)-based devices.