Front and Back contact engineering for high-efficient and low-cost hydrothermal derived Sb2(S, Se)3 solar cells by using FTO/SnO2 and carbon

Antimony chalcogenide Sb 2 (S, Se) 3 is attracting a lot of attention as photovoltaic absorber owing to its rewarding photoelectric properties, low toxicity, and earth abundance. However, its device efficiency is still limited by the absorber material quality and device interface recombination. In this work, a fluorine-doped tin oxide (FTO) substrate with ultra-thin SnO 2 layer and a low-cost stabilized carbon paste are introduced as a front and back contact layer respectively in Sb 2 (S, Se) 3 based planar solar cells. Over 5.2 % efficiency is demonstrated in the structure of FTO/SnO 2 /CdS/Sb 2 (S, Se) 3 /Carbon/Ag, where the Sb 2 (S, Se) 3 is prepared by hydrothermal technique. The complementary device physics characterizations reveal that the interfacial recombination between TCO and CdS is significantly suppressed by the introduction of ultra-thin SnO 2 layer, which is profited from the leakage protection and bandgap offset engineering by its high resistivity and suitable conduction band minimum. Meanwhile, the successful adoption of the low-cost stabilized carbon as a back contact here shows an enormous potential to replace the conventional organic hole transport materials and noble metal. We hope this work can provide positive guidance to optimize Sb 2 (S, Se) 3 based planar solar cells in the future.