Energy‐Resolved Electrochemical Impedance Spectroscopy—An Efficient and Powerful Tool for DOS Characterization in Semiconductors

The electronic band structures of semiconducting materials significantly influence the functionality of photoelectronic devices such as solar cells, light-emitting diodes, and sensors. The energy-resolved electrochemical impedance spectroscopy (ER-EIS) method presents an effective and efficient means of determining the density of states (DOS) function spanning the entire energy range from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), including the presence of tail states and deep defect states in the bandgap. This article reviews the nearly ten-year use of the ER-EIS method in semiconductor research from its introduction to the present. We detail the basic principles of this technique, highlighting both its advantages and limitations. Furthermore, we discuss the insights gained from applying ER-EIS to a diverse range of materials. Finally, we outline the directions and potential advancements that this method may bring to the field of materials science in the future.