Fast Fourier Transform Implementation for Determining Band Gap Energy from UV–Vis Spectra as a Fresh Methodology

Tauc plots have been massively used to determine the band gap energy E_g of semiconductors, but its implementation still possibility of erroneous estimates, which can be attributed by the straight-line method that involving subjective analysis of the researcher's own judgment. Here, we have collaborated Kubelka–Munk, Taylor expansion, and density functional theory calculation as general method and fast Fourier transform (FFT) as a fresh technique for determining more accurately band gap. Based on UV–Vis spectra analysis and QE simulation, the band gap range of TiO₂ from our calculation can be reported to be (3.26 ± 0.3) eV for a purity (~ 97.23%) with a crystallinity (~ 75%). It was found that FFT is a new viable comparison method to identify the suitable E_g of semiconductors, which is crucial for optimizing material design and tailoring their functionality for various applications.