Bifacial and Semitransparent Sb₂(S,Se)₃ Solar Cells for Single‐Junction and Tandem Photovoltaic Applications

Abstract Thin‐film solar cells are expected to play a significant role in the space industry, building integrated photovoltaic (BIPV), indoor applications, and tandem solar cells, where bifaciality and semitransparency are highly desired. Sb₂(S,Se)₃ has emerged as a promising new photovoltaic (PV) material for its high absorption coefficient, tunable bandgap, and nontoxic and earth‐abundant constituents. However, high‐efficiency Sb₂(S,Se)₃ solar cells exclusively employ monofacial architectures, leaving a considerable gap toward large‐scale application in aforementioned fields. Here, a bifacial and semitransparent Sb₂(S,Se)₃ solar cell and its extended application in tandem solar cells are reported. The transparent conductive oxides (TCOs) and the ultrathin inner n–i–p structure provide high long‐wavelength transmittance. Despite the MnS/ITO Schottky junction, power conversion efficiencies (PCEs) of 7.41% and 6.36% are achieved with front and rear illumination, respectively, contributing to a great bifaciality of 0.86. Consequently, the reported device gains great enhancement in PV performance by exploiting albedo of surroundings and shows exceptional capability in absorbing tilt incident light. Moreover, an Sb₂(S,Se)₃/Si tandem solar cell with a PCE of 11.66% is achieved in preliminary trials. These exciting findings imply that bifacial and semitransparent Sb₂(S,Se)₃ solar cells possess tremendous potential in practical applications based on their unique characteristics.