Investigating the Optical Band Gap of Various TiO2 Thin Films and MAPBI Perovskite Using UV-Vis Spectroscopy and Tauc Plot Analysis

Methylammonium lead iodide (MAPbI₃) and titanium dioxide (TiO₂) are promising materials for optoelectronic applications due to their superior optical properties. However, optimizing their efficiency for light absorption and conversion remains a challenge. This study aims to investigate the optical band gaps of TiO₂ thin films and MAPbI₃ perovskite using UV-Vis spectroscopy and Tauc plot analysis. TiO₂ thin films were synthesized via sol-gel techniques, spin coating, and thermal annealing, with three sample variations: TiO₂ 0.3 ml, TiO₂ 0.6 ml, and TiO₂ 1 ml. MAPbI₃ perovskite and mesoporous TiO₂ (m-TiO₂) were analyzed for comparison. Absorption coefficients were determined using the Beer-Lambert law. The UV-Vis spectra obtained showed strong absorption in the UV-visible range. Tauc plots determined band gap energies of -3.98 eV, -9.91 eV, -13.93 eV, 16.71 eV, and 5.97 eV for TiO₂ 0.3 ml, TiO₂ 0.6 ml, TiO₂ 1 ml, MAPbI₃, and m-TiO₂, respectively. These findings confirm the high efficiency of MAPbI₃ in photovoltaics and TiO₂’s potential in UV filtering and photocatalysis, emphasizing the need for further optimization on their properties and performance.