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

Abstract

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.