Heterojunction Annealing Enabling Record Open-Circuit Voltage in Antimony Triselenide Solar Cells

Despite the fact that antimony triselenide (Sb2Se3) thin-film solar cells have undergone rapid development in recent years, the large open-circuit voltage (V-OC) deficit still remains as the biggest bottleneck, as even the world-record device suffers from a large V-OC deficit of 0.59 V. Here, an effective interface engineering approach is reported where the Sb2Se3/CdS heterojunction (HTJ) is subjected to a post-annealing treatment using a rapid thermal process. It is found that nonradiative recombination near the Sb2Se3/CdS HTJ, including interface recombination and space charge region recombination, is greatly suppressed after the HTJ annealing treatment. Ultimately, a substrate Sb2Se3/CdS thin-film solar cell with a competitive power conversion efficiency of 8.64% and a record V-OC of 0.52 V is successfully fabricated. The device exhibits a much mitigated V-OC deficit of 0.49 V, which is lower than that of any other reported efficient antimony chalcogenide solar cell.