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Antimony trisulfide (Sb2S3) is a kind of emerging light-harvesting material with excellent stability and abundant elemental storage. Due to the quasi-one-dimensional symmetry, theoretical investigations have pointed out that there exist complicated defect properties. However, there is no experimental verification on the defect property. Here, we conduct optical deep-level transient spectroscopy to investigate defect properties in Sb2S3 and show that there are maximum three kinds of deep-level defects observed, depending on the composition of Sb2S3. We also find that the Sb-interstitial (Sbi) defect does not show critical influence on the carrier lifetime, indicating the high tolerance of the one-dimensional crystal structure where the space of (Sb4S6)n ribbons is able to accommodate impurities to certain extent. This study provides basic understanding on the defect properties of quasi-one-dimensional materials and a guidance for the efficiency improvement of Sb2S3 solar cells.

A proof‐of‐concept tandem solar cell using Sb2S3 and Sb2Se3 as top and bottom cell absorber materials is demonstrated. The bandgaps of Sb2S3 and Sb2Se3 are 1.74 and 1.22 eV, perfectly satisfying the requirement of tandem solar cells. The application of few‐layer graphene enables high transmittance and excellent interfacial contact in the top subcell. By controlling the thickness of the top cell for maximizing the spectral application, the tandem device delivers a power conversion efficiency of 7.93%, which outperforms the individually optimized top cell (5.58%) and bottom cell (6.50%). Mechanistical investigation shows that the tandem device is able to make up voltage loss in the subcells, which is a critical concern in the current antimony chalcogenide solar cells. This study provides an alternative approach to enhancing the energy conversion efficiency of antimony selenosulfide.

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Antimony selenosulfide (Sb2(S,Se)3) is an emerging low‐cost, nontoxic solar material with suitable bandgap and high absorption coefficient. Developing effective methods for fabricating high‐quality films would benefit the device efficiency improvement and deepen the fundamental understanding on the optoelectronic properties. Herein, equipment is developed that allows online introduction of precursor vapor during the reaction process, enabling sequential coevaporation of Sb2Se3 and S powders for the deposition of Sb2(S,Se)3 thin films. With this unique ability, it is revealed that the deposition sequence manipulates both the interfacial properties and optoelectronic properties of the absorber film. A power conversion efficiency of 8.0% is achieved, which is the largest value in vapor‐deposition‐derived Sb2(S,Se)3 solar cells. The research demonstrates that multi‐source sequential coevaporation is an efficient technique to fabricate high‐efficiency Sb2(S,Se)3 solar cells.

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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.

Antimony selenosulfide, Sb2(SxSe1−x)3, has been considered as a promising light harvesting material for low-cost, non-toxic, and stable solar cell applications. However, current preparation methods of Sb2(SxSe1−x)3 suffer from low-quality films, which hampers the performance improvement in Sb2(SxSe1−x)3-based solar cells. Herein, we develop a pulsed laser deposition technique to fabricate antimony selenosulfide films with flat and compact surface morphology and high crystallinity. The composition of the as-obtained films can be conveniently tuned via varying molar ratios of Sb2S3 and Se in targets. At optimized conditions, we fabricate planar heterojunction solar cells and then obtain a significantly improved power conversion efficiency of 7.05%. Our research offers a facile and robust preparation method for Sb2(SxSe1−x)3 films with enhanced photovoltaic properties.