Germanium Selenide: A Critical Review on Recent Advances in Material Development for Photovoltaic and Photoelectrochemical Water‐Splitting Applications

Abstract

Germanium selenide (GeSe), a new 2D semiconductor material, is an attractive material due to its excellent optoelectronic properties, which hold tremendous promise in a wide range of applications, including thin‐film solar cells (TFSCs) and photoelectrochemical (PEC) water splitting. Several attempts have been made to date in theoretical studies, high‐quality GeSe material synthesis, evaluating absorber properties, and developing efficient TFSCs and PEC devices. Using existing device topologies for chalcogenide materials, TFSCs with 5.2% efficiency and a PEC device with 3.17% solar‐to‐hydrogen efficiency have been recently developed. To enable its potential in high performances of TFSCs and PEC devices for future large‐scale applications, further improvement in materials quality, device design, and development is required. In this regard, this review provides a comprehensive overview of current advances made in GeSe material development and applications in TFSCs and PEC devices. First, the fundamental properties of GeSe material, theoretical studies, as well as in‐depth synthesis methods, are outlined. Then, key developments in GeSe‐based TFSCs and PEC devices are discussed with an emphasis on device designs. Finally, the most prominent impediments to a fundamental understanding of materials are highlighted, and perspectives on future research directions for improving material quality and device efficiency are provided.