Synthesis, structural and optical properties of lead free Cs2CuBiCl6: A potential & promising eco-friendly double perovskite for solar cell applications

Lead-free halide-based double perovskite (DP) compounds have grasped the interest of the research community as a potential alternative to the toxicity-degradability problems associated with lead-halide single perovskites. In this study, we have synthesized a potential & promising nontoxic halide DP Cs₂CuBiCl₆ for the very first time by adopting a new chemical synthesis route. Herein, we have examined the optical, surface, and structural characteristics of synthesized DP. X-ray diffraction (XRD) has been done to inspect its structural behavior and the obtained peaks are in good agreement with reference data. Moreover, the morphology of synthesized material has been confirmed by scanning electron microscopy (SEM). Further, the optical study done by measuring photoluminescence (PL) spectra provides a broad peak at 500 nm due to intraband transition. The electronic property of DP Cs₂CuBiCl₆ has been studied by calculating the direct bandgap of 1.57 eV. The synthesized DP material is a small bandgap material in comparison with the bulky materials and its property is similar to the lead perovskites. In additionally, we built a photovoltaic effect based solar cell device, and we have measured the illuminated and dark I–V characteristics, and estimated the power conversion efficiency of the fabricated device. The acquired power conversion efficiency (PCE) of solar cells device is 1.87%, which is comparable with the previous studies of double perovskites and it can be lead halide single perovskite counterpart. This investigation opens a new and realistic approach for the synthesis and study of lead-free DP for remarkable photovoltaic applications in green technology domain.