Metal oxide and its modification as photoanode for dye-sensitized solar cell: a review

Dye-sensitized solar cells (DSSCs) represent the promising third generation of solar cell technology. This review begins with the introduction of various generations of solar cells, followed by a discussion of the structure and charge-transport mechanisms of DSSCs, and the properties of several metal oxides. This paper provides a comprehensive review of the metal oxide modification as a photoanode for DSSCs taken from the latest publication. The metal oxides are modified using three main methods, namely, doping, composite, and coating. The modification reduces charge transfer resistance (Rct), energy gap (Eg) while increasing carrier lifetime (τ), thereby improving the power conversion efficiency (η) of the device. This paper highlights the relationship between η and Rct obtained from electrochemical impedance spectroscopy (EIS). Future prospects and challenges associated with each modification strategy are also discussed. The goal is to guide future research and development of DSSCs toward high efficiency and easy scalability for commercial use.