Room temperature synthesis of double perovskite Cs2AlBiCl6 for photovoltaic applications

Abstract

Toxicity and stability issue in lead halide inorganic perovskite nanomaterial can be solved with the help of lead free double perovskite (DP) nanocrystals (NCs). Herein, we have synthesized a new halide double perovskite material Cs2AlBiCl6 for the first time and explored its structural and optical properties which further shows remarkable similarities to lead induced compounds. Also, in this article we have demonstrated the solar cell device based on the synthesized material showing power conversion efficiency of 1.965% which is remarkable and comparable to the single perovskites based solar cell devices. This material is showing promising absorbance phenomenon with a direct and indirect band gap of 3.23 eV and 2.63 eV respectively with excellent stability under ambient condition. The formation of synthesized double perovskite phase has been confirmed using X-ray powder diffraction (XRD) which results into a high purity and good crystallinity of the material. The temperature dependent photoluminescence (TDPL) phenomenon from 19 K to 300 K has been recorded to understand the luminescent behavior of the material. An excellent photoluminescence has been observed due to self-trapped exciton (STE) emission attributed to the distortion in the lattice. A decrease in intensity with increase in temperature has been observed due to conversion of excitons into free carriers with the help of thermal energy. This novel experimental study suggest the utility of Cs2AlBiCl6 as a stable and green alternatives for optoelectronic applications and provide a broad and undiscovered compositional space for finding promising semiconducting materials for optoelectronic and photovoltaic devices applications.