Quasi-vertical orientated antimony sulfide inorganic thin film solar cells achieved by vapor transport deposition.

The one-dimensional photovoltaic absorber material Sb2S3 requires crystal orientation engineering to enable efficient carrier transport. In this work, we adopted a vapor transport deposition (VTD) method to fabricate vertically aligned Sb2S3 on a CdS buffer layer. Our work shows that such a preferential vertical orientation arises from the sulfur deficit of the CdS surface which creates a beneficial bonding environment between exposed Cd2+ dangling bonds and S atoms in the Sb2S3 molecules. The CdS/VTD-Sb2S3 interface recombination is suppressed by such properly aligned ribbons at the interface. Compared with typical [120]-oriented Sb2S3 films deposited on CdS by rapid thermal evaporation (RTE) method, the VTD-Sb2S3 thin film is highly [211]- and [121]- oriented and the performance of the solar cell is increased considerably. Without using any hole transportation layer, a conversion efficiency of 4.73% is achieved with device structure of ITO/CdS/Sb2S3/Au. This work provides a potential way to acquire vertical aligned thin films on different buffer layers.