Interface engineering of antimony selenide solar cells: a review on the optimization of energy band alignments

Abstract Earth-abundant and environmentally benign antimony selenide (Sb 2 Se 3 ) has emerged as a promising light-harvesting absorber for thin-film photovoltaic (PV) devices due to its high absorption coefficient, nearly ideal bandgap for PV applications, excellent long-term stability, and intrinsically benign boundaries if properly aligned on the substrate. The record power conversion efficiency of Sb 2 Se 3 solar cells has currently reached 9.2%, however, it is far lower than the champion efficiencies of other chalcogenide thin-film solar cells such as CdTe (22.1%) and Cu(In,Ga)Se 2 (23.35%). The inferior device performance of Sb 2 Se 3 thin-film solar cells mainly results from a large open-circuit voltage deficit, which is strongly related to the interface recombination loss. Accordingly, constructing proper band alignments between Sb 2 Se 3 and neighboring charge extraction layers through interface engineering to reduce carrier recombination losses is one of the key strategies to achieving high-efficiency Sb 2 Se 3 solar cells. In this review, the fundamental properties of Sb 2 Se 3 thin films, and the recent progress made in Sb 2 Se 3 solar cells are outlined, with a special emphasis on the optimization of energy band alignments through the applications of electron-transporting layers and hole-transporting layers. Furthermore, the potential research directions to overcome the bottlenecks of Sb 2 Se 3 thin-film solar cell performance are also presented.