Bifacial And Semitransparent Sb 2 (S,Se) 3 Solar Cells for Single-Junction And Tandem Photovoltaic Applications.

Thin film solar cells, as a complement to silicon 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. Sb 2 (S,Se) 3 has emerged as a promising new photovoltaic (PV) material for its high absorption coefficient, tuneable bandgap, and non-toxic and earth-abundant constituents. However, high-efficiency Sb 2 (S,Se) 3 solar cells so far exclusively employ gold back contacts or Mo-coated glass substrates, which only allows monofacial architectures, leaving a considerable gap towards large-scale application in aforementioned fields. Here, we report a bifacial and semitransparent Sb 2 (S,Se) 3 solar cell enabled by a fluorine-doped tin oxide substrate and an indium tin oxide (ITO) back contact, and its extended application in tandem solar cells. The transparent conductive oxides (TCOs) and the ultra-thin inner n-i-p structure provide high transmittance at the long wavelength region. Despite of the unfavourable Schottky junction and increased defect density at MnS/ITO interface, a power conversion efficiency (PCE) of 7.41% with only front illumination is achieved. On the other hand, though the varied carrier kinetic with rear illumination has a negative impact on the PCE, the internal ultrathin fully depleted absorber layer enables it to remain at a satisfying level at 6.36%, contributing to a great bifaciality of 0.86. As a result, our bifacial and semitransparent Sb 2 (S,Se) 3 solar cells can gain great enhancement in PV performance by exploiting albedo of surroundings and show exceptional capability in absorbing non-normal incident light. Moreover, our device can be integrated into a tandem solar cell with a bottom silicon solar cell owing to its adjustable bandgap. A Sb 2 (S,Se) 3 /Si tandem solar cell with PCE of 11.66% is achieved in our preliminary trial. These exciting findings imply that bifacial and semitransparent Sb 2 (S,Se) 3 solar cells possess tremendous potential in practical applications based on their unique characteristics. This article is protected by copyright. All rights reserved.