Enhanced Electronic Structure, Phase, and Morphology of a CH₃NH₃PbI₃ Perovskite Solar Cell Using Vanadium Copper Sulfide (VCuS) Nanoparticle Treatment

Achieving high-performance perovskite solar cells with satisfactory efficiency requires a decrease of charge carrier recombination and intrinsic density of defects in organic and inorganic halide perovskite absorber materials. In this study, the effect of vanadium copper sulfide (VCuS) nanoparticles (NPs) used to accelerate CH₃NH₃PbI₃ perovskite crystallization in a single phase is investigated. The results indicate that the employed VCuS NPs influence the purity, formation of a single phase, and crystallinity of CH₃NH₃PbI₃ perovskite with favorable crystal growth in the (110) direction. The morphological analysis indicates the existence of a dense, compact, and homogeneous structure, which is associated with a large grain size that extends the lifetime and reduces recombination by increasing the electron-hole diffusion length. According to its optical characteristics, perovskite has an energy gap between 1.62 and 1.6 eV for visible light and an absorption coefficient in excess of 10⁵ cm^{− 1}. Photoluminescence (PL) measurements revealed that when VCuS NPs were added to perovskite thin films, the PL intensity decreased, indicating a decrease in charge recombination. For sample 8 mg/mL-VCuS, the bulk heterojunction solar cells demonstrated a power conversion efficiency (PCE) of 15.11%, a short-circuit current density (Jsc) of 20.93 mA/cm², an open-circuit voltage (Voc) of 1.043 V, and a fill factor (FF) of 69.23%. In addition to enhancing light harvesting efficiency, this superior doped perovskite film eliminates pinholes, which reduces charge recombination in solar cells.