Cadmium-free ZnS interfacial layer for hydrothermally processed Sb2S3 solar cells

Abstract There is a concomitant interest in reducing carbon footprint and harvesting solar energy with environmentally-friendly materials. In this context, the recent hydrothermal deposition of antimony sulfide is considered promising for low-cost and simple fabrication of photovoltaic devices. However, the need for a CdS film as buffer layer is still a drawback to this approach. In this study, a new strategy by adding a Cd-free ZnS interlayer obtained by successive ionic layer adsorption and reaction method between TiO2 and Sb2S3 film is explored. The structural and morphological characterization of hydrothermally deposited Sb2S3 on TiO2 with and without a ZnS interlayer demonstrate that these films have different crystal orientation and surface morphologies. The champion Sb2S3 solar cell based on ZnS interlayer achieves a power conversion efficiency (PCE) of 5.01%, whereas devices fabricated with pristine TiO2 yields a PCE of 3.42% under similar conditions. Diffusion coefficient, electron diffusion length and interfacial charge recombination measurements show the beneficial effect of adding a ZnS interlayer on the performance properties of hydrothermally processed Sb2S3 solar cells.