Composition engineering of Sb2S3 film enabling high performance solar cells.

Sb2S3 is a kind of stable light absorption materials with suitable band gap, promising for practical applications. Here we demonstrate that the engineering on the composition ratio enables significant improvement in the device performance. We found that the co-evaporation of sulfur or antimony with Sb2S3 is able to generate sulfur- or antimony-rich Sb2S3. This composition does not generate essential influence on the crystal structure, optical band and film formability, while the carrier concentration and transport dynamics are considerably changed. The device investigations show that sulfur-rich Sb2S3 film is favorable for efficient energy conversion, while antimony-rich Sb2S3 leads to greatly decreased device performance. With optimizations on the sulfur-rich Sb2S3 films, the final power conversion efficiency reaches 5.8%, which is the highest efficiency in thermal evaporation derived Sb2S3 solar cells.

Aqueous-Solution-Based Approach Towards Carbon-Free Sb2 S3 Films for High Efficiency Solar Cells.

Sb2 S3 is a new kind of photovoltaic material that is promising for practical application in solar cells owing to its suitable bandgap, earth-abundant elements, and excellent stability. Here, we report on an aqueous-solution-based approach for the synthesis of Sb2 S3 films from easily accessible Sb2 O3 as antimony source. In this reaction, 3-mercaptopropionic acid was applied as both solvent and sulfur precursor, aqueous ammonia was employed as a solvent. After simple annealing at a temperature as low as 270 °C, the spin-coated precursor solution can generate compact, flat, uniform, and well-crystallized Sb2 S3 film. Mechanistic study showed that the formation of Sb-complex with ammonium carboxylates leads to the successful dissolution of Sb2 O3 powder. A suitable annealing process was able to generate carbon-free Sb2 S3 films. Planar heterojunction solar cell based on the as-prepared Sb2 S3 film delivered a power conversion efficiency of 5.57 %, which is the highest efficiency of solution-processed planar heterojunction Sb2 S3 solar cells and a high value in all kinds of Sb2 S3 solar cells. This research provides a convenient approach for the fabrication of device-quality Sb2 S3 films, and highlights solution processing of carbon-free metal chalcogenide thin films as a suitable process for application in optoelectronic devices.

V2O5 as Hole Transporting Material for Efficient All Inorganic Sb2S3 Solar Cells.

This research demonstrates that V2O5 is able to serve as hole transporting material to substitute organic transporting materials for Sb2S3 solar cells, offering all inorganic solar cells. The V2O5 thin film is prepared by thermal decomposition of spin-coated vanadium(V) triisopropoxide oxide solution. Mechanistic investigation shows that heat treatment of V2O5 layer has crucial influence on the power conversion efficiency of device. Low temperature annealing is unable to remove the organic molecules that increases the charge transfer resistance, while high temperature treatment leads to the increase of work function of V2O5 that blocks hole transporting from Sb2S3 to V2O5. Electrochemical and compositional characterizations show that the interfacial contact of V2O5/Sb2S3 can be essentially improved with appropriate annealing. The optimized power conversion efficiency of device based on Sb2S3/V2O5 heterojunction reaches 4.8%, which is the highest power conversion efficiency in full inorganic Sb2S3-based solar cells with planar heterojunction solar cells. Furthermore, the employment of V2O5 as hole transporting material leads to significant improvement in moisture stability compared with the device based organic hole transporting material. Our research provides a material choice for the development of full inorganic solar cells based on Sb2S3, Sb2(S,Se)3, and Sb2Se3.