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Sb 2 S 3 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 Sb 2 S 3 is able to generate sulfur- or antimony-rich Sb 2 S 3 . 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 Sb 2 S 3 film is favorable for efficient energy conversion, while antimony-rich Sb 2 S 3 leads to greatly decreased device performance. With optimizations on the sulfur-rich Sb 2 S 3 films, the final power conversion efficiency reaches 5.8%, which is the highest efficiency in thermal evaporation derived Sb 2 S 3 solar cells., (Copyright © 2018 Science China Press. Published by Elsevier B.V. All rights reserved.)

Sb 2 S 3 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 Sb 2 S 3 films from easily accessible Sb 2 O 3 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 Sb 2 S 3 film. Mechanistic study showed that the formation of Sb-complex with ammonium carboxylates leads to the successful dissolution of Sb 2 O 3 powder. A suitable annealing process was able to generate carbon-free Sb 2 S 3 films. Planar heterojunction solar cell based on the as-prepared Sb 2 S 3 film delivered a power conversion efficiency of 5.57 %, which is the highest efficiency of solution-processed planar heterojunction Sb 2 S 3 solar cells and a high value in all kinds of Sb 2 S 3 solar cells. This research provides a convenient approach for the fabrication of device-quality Sb 2 S 3 films, and highlights solution processing of carbon-free metal chalcogenide thin films as a suitable process for application in optoelectronic devices., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

This research demonstrates that V 2 O 5 is able to serve as hole transporting material to substitute organic transporting materials for Sb 2 S 3 solar cells, offering all inorganic solar cells. The V 2 O 5 thin film is prepared by thermal decomposition of spin-coated vanadium(V) triisopropoxide oxide solution. Mechanistic investigation shows that heat treatment of V 2 O 5 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 V 2 O 5 that blocks hole transporting from Sb 2 S 3 to V 2 O 5 . Electrochemical and compositional characterizations show that the interfacial contact of V 2 O 5 /Sb 2 S 3 can be essentially improved with appropriate annealing. The optimized power conversion efficiency of device based on Sb 2 S 3 /V 2 O 5 heterojunction reaches 4.8%, which is the highest power conversion efficiency in full inorganic Sb 2 S 3 -based solar cells with planar heterojunction solar cells. Furthermore, the employment of V 2 O 5 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 Sb 2 S 3 , Sb 2 (S,Se) 3 , and Sb 2 Se 3 .