Beschreibung:
<jats:title>Abstract</jats:title><jats:p>The <jats:italic>Tauc plot</jats:italic> is a method originally developed to derive the <jats:italic>optical gap</jats:italic> of amorphous semiconductors such as amorphous germanium or silicon. By measuring the absorption coefficient <jats:italic>α</jats:italic>(<jats:italic>hν</jats:italic>) and plotting versus photon energy <jats:italic>hν</jats:italic>, a value for the <jats:italic>optical gap</jats:italic> (<jats:italic>Tauc gap</jats:italic>) is determined. In this way <jats:italic>non‐direct</jats:italic> 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 <jats:italic>direct</jats:italic> and <jats:italic>indirect</jats:italic> interband transitions. For this purpose, (<jats:italic>ahν</jats:italic>)<jats:sup><jats:italic>n</jats:italic></jats:sup> (<jats:italic>n</jats:italic> = , 2) is plotted against <jats:italic>hν</jats:italic> to determine a value of the <jats:italic>electronic bandgap</jats:italic>. 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 <jats:italic>Tauc plot</jats:italic> for (poly‐) crystalline solids and to which material classes this applies. This study aims to close this gap by discussing the <jats:italic>Tauc plot</jats:italic> and its limiting factors for exemplary (poly‐) crystalline solids with different electronic structures.</jats:p>