Boosting perovskite solar cell efficiency with ball-milled Er3+-doped TiO2 as an electron transport layer

Organic-inorganic perovskite solar cells (PSCs) are an innovative advancement in photovoltaic technology. The superior optical characteristics of titanium dioxide (TiO₂) contribute to the progress of PSCs. In this study, Er-doped TiO₂ fabrication using the ball mill technique is reported. It has been claimed that the efficiency of organic–inorganic lead halide perovskite-based solar cells can be increased by using Er-doped TiO₂ cells as an electron transportation layer (ETL). The change in crystal structures and nanostructure was investigated using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). The average crystal size of TiO₂ was reduced from 17.43 nm to 15.59 nm by the addition of Er³⁺. The optical characteristics were explained by UV–visible spectroscopy and photoluminescence (PL). Optical absorption indicates that the doping with Er makes a blue shift in the absorption edge; consequently, a band gap decreases from 3.41 to 3.38 eV and then increases up to 3.45 eV, while the absorption intensity decreases in the visible region. Doping resulted in a rise in fluorescence emission (PL), which corresponds to the intermediate levels created by Er ions. All doped samples exhibit higher power conversion efficiency (PCE) of up to 13.38 % than the pure one of 9.31 %. Er-doped TiO₂ nanoparticles have a 30.42 % enhancement in performance on the PSC. This research presents a simple and effective method for synthesizing Er-doped TiO₂ nanoparticles, significantly advancing PSC efficiency.