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.