Recent Progress in GeSe Thin-Film Solar Cells

Germanium monoselenide (GeSe) is a promising photovoltaic absorber material for thin-fihn solar cells due to its appropriate bandgap (about 1.14 eV), high absorption coefficient (>10(5) cm(-1) at visible light), large carrier mobility (about 128.7 cm(2).V-1.s(-1)) and benign defect properties arising from its antibonding states at the valence band maximum. The theoretical Shockley-Quiesser efficiency limit for GeSe single junction solar cells determined by its bandgap is above 30%. Moreover, this simple binary compound possesses earth-abundant, nontoxic constituents and high stability in ambient atmosphere. The easy sublimation feature of GeSe enables the deposition of high-quality films through an industrial close-space sublimation method. The fundamental properties of GeSe with emphasis on the material, optical, electrical, and defect properties are introduced, and then the recent progress of fabrication of GeSe thin films and solar cells is summarized. Finally, a brief perspective on the further development of GeSe thin-film solar cells is provided.