Limitations of the Tauc Plot Method

Abstract

The Tauc plot is a method originally developed to derive the optical gap of amorphous semiconductors such as amorphous germanium or silicon. By measuring the absorption coefficient α(hν) and plotting versus photon energy hν, a value for the optical gap (Tauc gap) is determined. In this way non‐direct optical transitions between approximately parabolic bands can be examined. In the last decades, a modification of this method for (poly‐) crystalline semiconductors has become popular to study direct and indirect interband transitions. For this purpose, (ahν)n (n = , 2) is plotted against hν to determine a value of the electronic bandgap. Due to the ease of performing UV–vis measurements, this method has nowadays become a standard to analyze various (poly‐) crystalline solids, regardless of their different electronic structure. Although this leads partially to widely varying values of the respective bandgap of nominally identical materials, there is still no study that critically questions which peculiarities in the electronic structure prevent a use of the Tauc plot for (poly‐) crystalline solids and to which material classes this applies. This study aims to close this gap by discussing the Tauc plot and its limiting factors for exemplary (poly‐) crystalline solids with different electronic structures.

2D/1D PbI2/Sb2S3 van der Waals heterojunction for highly sensitive and broadband photodetectors

“…Given that PbI 2 is a two-dimensional excitonic material, its bandgap ( E g ) can be examined through by PL results. 36 For Sb 2 S 3 microrods, its optical bandgap ( E g,opt ) can be determined to be ∼1.61 eV as reported in our recent work. 18…”

“…Given that PbI 2 is a twodimensional excitonic material, its bandgap (E g ) can be examined through by PL results. 36 For Sb 2 S 3 microrods, its optical bandgap (E g,opt ) can be determined to be B1.61 eV as reported in our recent work. 18 Furthermore, steady-state photoluminescence (PL) and time-resolved PL (TRPL) spectra were explored to comprehensively understand the charge carrier transfer and recombination behaviors in the PbI 2 nanosheets.…”

Facile Preparation of the ZnSe/Ag2Se Binary Heterojunction for Photocatalytic Antibacterial Efficiency

“…The inset in Figure a further reflects the color transition of the catalysts from yellow to black. Figure c,d displays the band gap plots obtained via the Tauc plot method, revealing band gaps of 2.60 eV for ZnSe and 1.25 eV for Ag 2 Se, respectively . The VB-XPS test results for ZnSe and Ag 2 Se are presented in Figure e,f.…”

Gas–Liquid Interface Route to Hybrid Copper Bromine Perovskite Single-Crystal Membrane with Dielectric Transitions and Ferromagnetic Exchanges

“…UV–vis-IR spectroscopy measurements on [HCMA] 2 CuBr 4 (Figure a). The absorption spectra were calculated from reflectance spectra by using the Kubelka–Munk function (eq ), where α is the absorption coefficient and S is the scattering coefficient. The optical gap E g value of [HCMA] 2 CuBr 4 is 0.99 eV. α / S = false( 1 − R false) 2 / 2 R …”