Sb2S3 Seed-Mediated Growth of Low-Defect Sb2S3 on a TiO2 Substrate for Efficient Solar Cells

Hydrothermal deposition was recently developed to prepare an antimony selenosulfide thin film with large grain size and flat and compact surface morphology, leading to efficient breakthrough in solar cell applications. However, the deposition of antimony chalcogenide is always based on the CdS substrate. The narrow band gap of CdS generates parasitic absorption that causes light harvesting loss in the solar device. TiO2 with a wide band gap allows more efficient light harvesting, while its deposition on high-quality antimony chalcogenide films has not been realized. Here, we demonstrate that the Sb2S3 seed layer introduced on the TiO2 surface can initiate the deposition of Sb2S3. The Sb2S3 seed layer provides crystal nuclei for the hydrothermal growth of a highly dense and compact Sb2S3 film on the TiO2 substrate. This kind of Sb2S3 film exhibits reduced defect density and improved charge-carrier transport compared with that deposited on a bare TiO2 surface, finally leading to an efficiency improvement of 32%. This method provides an effective strategy for depositing Sb2S3 on wide band gap oxide substrates in the hydrothermal deposition system for optoelectronic device applications.