Self-assembled growth of quasi-vertically oriented Sb2S3 thin films for substrate structured solar cells

Antimony sulfide (Sb2S3) is an appealing one-dimensional light-harvesting material for thin-film solar cells due to the high absorption coefficient, suitable bandgap and abundance of constituent elements. The orientation of the Sb2S3 thin film is considered as one of the most important factors affecting the performance of the device. According to the minimum energy principle, Sb2S3 is prone to grow parallel to the substrate along the [hk0] orientation which is harmful to the device performance. On the other hand, [hk1]-oriented films are much more beneficial but additional processes such as annealing are often required. In this work, stoichiometric Sb2S3 thin films consist of compact, highly [hk1]-oriented grains have been prepared via a self-assembled growth by magnetron sputtering and post-sulfurization. After carefully optimized the preparation process, a champion device (2.89% power conversion efficiency) was obtained with an open-circuit voltage of 696 mV and a short-circuit current density of 12.48 mA/cm2 under AM 1.5G solar radiation. Interestingly, the high open-circuit voltage of our device is already comparable to the state-of-the-art Sb2S3 solar cells. This work demonstrates a great potential of the sputtering and post-sulfurization method in fabrication of high-efficiency substrate Sb2S3 thin-film solar cells.