Metal-Doped TiO2 Thin Film as an Electron Transfer Layer for Perovskite Solar Cells: A Review

The electron transfer layer (ETL) plays a vital role in achieving high-performance perovskite solar cells (PSCs). Titanium dioxide (TiO2) is primarily utilised as the ETL since it low-cost, chemically stable, and has simplest thin-film preparation methods. However, TiO2 not an ideal because leads to low conductivity, conduction band mismatch, unfavourable mobility. In addition, exposure of ultraviolet light induces formation oxygen vacancies at surface. To overcome these issues, doping with various metal ions favourable improve surface structure properties electronic properties. This review focuses on bulk modification via concentrations electrical optical properties, charge carrier density, interfacial electron–hole recombination, thus contributing enhancing power conversion efficiency (PCE) PSCs.