Templated Growth and Passivation of Vertically Oriented Antimony Selenide Thin Films for High-Efficiency Solar Cells in Substrate Configuration

Antimony selenide (Sb₂Se₃) is a promising low-cost photovoltaic material with a 1D crystal structure. The grain orientation and defect passivation play a critical role in determining the performance of polycrystalline Sb₂Se₃ thin-film solar cells. Here, a seed layer is introduced on a molybdenum (Mo) substrate to template the growth of a vertically oriented, columnar Sb₂Se₃ absorber layer by closed space sublimation. By controlling the grain orientation and compactness of the Sb₂Se₃ seeds, obtain high-quality Sb₂Se₃ absorber layers with passive Sb₂Se₃/Mo interfaces is obtained, which in turn improve the transport of photoexcited charge carriers through the absorber layer and its interfaces. Post-deposition annealing of absorber layers in ambient air is further utilized to passivate the defects in Sb₂Se₃ and enhance the quality of the front heterojunction. As a result of systematic processing optimization, Sb₂Se₃ planar heterojunction solar cells are fabricated in substrate configuration with a champion power conversion efficiency of 8.5%.