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.