Synthesis, crystal structure, optical properties, thin-film deposition, and SCAPS-1D simulation of a new lead-free 2D hybrid perovskite (C6H7NBr)2[CuCl4] for potential photovoltaic applications.

A novel lead-free two-dimensional (2D) hybrid perovskite, (C6H7NBr)2[CuCl4], was synthesized via slow evaporation at room temperature and successfully deposited as relatively homogeneous thin films using a simple one-step spin-coating method. It was characterized by single-crystal X-ray diffraction, spectroscopic techniques, and thermal analysis. The compound crystallizes in the orthorhombic non-centrosymmetric space group Pca21, forming layered CuCl6 octahedra separated by 4-bromoanilinium cations. It exhibits a direct optical bandgap of 2.30 eV. Hirshfeld surface analysis further provided detailed insight into crystal packing and intermolecular interactions. The photovoltaic potential of this new perovskite as a light absorber layer was theoretically evaluated using SCAPS-1D simulations in the device configuration FTO/TiO2/(C6H7NBr)2[CuCl4]/Spiro-OMeTAD/Au. The optimized device parameters yielded a fill factor (FF) of 71.50%, an open-circuit voltage (V oc) of 1.2 V, and a power conversion efficiency (PCE) approaching 10%. These findings demonstrate the strong potential of this environmentally friendly copper-based perovskite for promising lead-free photovoltaic applications, contributing to the advancement of sustainable and scalable solar energy technologies.