Sputtered and selenized Sb2Se3 thin-film solar cells with open-circuit voltage exceeding 500 mV

Antimony selenide (Sb2Se3) is a potential absorber material for environment-friendly and cost-efficient photovoltaics and has achieved considerable progress in recent years. However, the severe open-circuit voltage (V-oc) deficit ascribed to the interface and/or bulk defect states has become the main obstacle for further efficiency improvement. In this work, Sb2Se3 absorber layer was prepared by an effective combination reaction involving sputtered and selenized Sb precursor thin films. The self-assembled growth of Sb2Se3 thin films with large crystal grains, benign preferential orientation, and accurate chemical composition were successfully fulfilled under an appropriate thickness of Sb precursor and an optimized selenization scenario. Substrate structured Sb2Se3 thin-film solar cells, a champion device with a power-conversion efficiency of 6.84%, were fabricated. This device is comparable to state-of-the-art ones and represents the highest efficiency of sputtered Sb2Se3 solar cells. Importantly, the high V-oc of 504 mV is closely related to the reduced deep level defect density for the Sb2Se3 absorber layer, the passivated interfacial defects for Sb2Se3/CdS heterojunction interface, and the additional heterojunction heat treatment-induced Cd and S inter-diffusion. This significantly improved Voc demonstrates remarkable potential to broaden its scope of applications for Sb2Se3 solar cells.