(C₆H₅CH₂NH₃)₂CuBr₄: A Lead-Free, Highly Stable Two-Dimensional Perovskite for Solar Cell Applications

The toxicity and the instability of lead-based perovskites might eventually hamper the commercialization of perovskite solar cells. Here, we present the optoelectronic properties and stability of a two-dimensional layered (C6H5CH2NH3)2CuBr4 perovskite. This material has a low Eg of 1.81 eV and high absorption coefficient of ∼1 × 105 cm–1 at the most intensive absorption at 539 nm, implying that it is suitable for light-harvesting in thin film solar cells, especially in tandem solar cells. Furthermore, X-ray diffraction (XRD), ultraviolet–visible (UV–vis) absorption spectra, and thermogravimetric analysis (TGA) confirm the high stability toward humidity, heat, and ultraviolet light. Initial studies produce a mesoscopic solar cell with a power conversion efficiency of 0.2%. Our work may offer some useful inspiration for the further investigation of environment-friendly and stable organic–inorganic perovskite photovoltaic materials.