Uncovering the Role of Electronic Doping In Lead-free Perovskite (CH3NH3)2CuCl4-xBrx and Solar Cells Fabrication

Lead halide perovskites are attractive pigments to fabricate solar cells in the laboratory owing to their high power conversion efficiency. However, such materials also possess a high level of toxicity that is carcinogenic for humans and aquatic life due to the presence of Pb. Arguably, this hampers their acceptability for immediate commercialization. Here, we report the synthesis of two-dimensional copper-based perovskite as an environmentally benign alternative to lead-based perovskites. We evaluated their optoelectronic properties and photovoltaic parameters. The (CH₃NH₃)₂CuCl_4-xBr_x with X = 0.3 and 0.66 are derivatives of the stable MA₂CuCl₄. The single crystals and powders diffractograms suggest compositions with varying Cl/Br ratios and different bromine localization in the inorganic framework. We noted a narrow absorption for copper mixed halide perovskite with a bandgap from 2.85 − 2.65 eV related to the halide ratio variation (crystal color variation). Our findings demonstrate the impact of halide to optimize the stability of methyl-ammonium copper perovskite and provide an effective pathway to design eco-friendly perovskites for electrooptical application.