1. Use and misuse of the Kubelka-Munk function to obtain the band gap energy from diffuse reflectance measurements
- Author
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Elisabete F. Freitas, Carlos J. Tavares, Mikhail Vasilevskiy, Iran Rocha Segundo, Joaquim A. O. Carneiro, Salmon Landi, and Universidade do Minho
- Subjects
Materials science ,Diffuse reflectance infrared fourier transform ,Band gap ,Tauc plot ,02 engineering and technology ,Electron ,Kubelka-Munk model ,01 natural sciences ,0103 physical sciences ,Materials Chemistry ,010302 applied physics ,Science & Technology ,business.industry ,General Chemistry ,Function (mathematics) ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Amorphous solid ,Computational physics ,Semiconductor ,Diffuse reflectance ,Crystallite ,Diffuse reflection ,Band gap energy ,0210 nano-technology ,business - Abstract
The determination of the optical band gap energy ( E g ) is important for optimization of the generation of electron/hole pairs in semiconductor materials under illumination. For this purpose, the classical theory proposed by Kubelka and Munk (K-M) has been largely employed for the study of amorphous and polycrystalline materials. In this paper, the authors demonstrate, step by step, how to use the K-M function and apply it thoroughly to the determination of the E g of TiO2 semiconductor powder (pressed at different thicknesses) from diffuse reflectance spectroscopy (DRS) measurements. For the sample thicknesses 1–4 mm, E g values of 3.12–3.14 eV were obtained. With this work it is envisaged a clarification to the procedure of determination of the E g from the K-M theory and DRS data, since some drawbacks, and misconceptions have been identified in the recent literature. In particular, the widely used practice of determining the E g of a material directly from the K-M function is found to be inadequate.
- Published
- 2022