Investigating the Optical Band Gap of Various TiO2 Thin Films and MAPBI Perovskite Using UV-Vis Spectroscopy and Tauc Plot Analysis
Omoriwhovo Jude Oghenekome *
Department of Physics, Delta State University, Abraka, Nigeria.
Asare Godfred Kesse
Department of Physics and Astronomy, Ball State University, Muncie, Indiana, USA.
Ogburogho Godwin
Department of Physics, Delta State University, Abraka, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
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.
Keywords: Titanium dioxide, perovskite, optical band gap, UV-Vis spectroscopy, Tauc plot