The role of grain growth in controlling the crystal orientation of Sb2S3 films for efficient solar cells

Abstract

The orientation of antimony sulfide (Sb₂S₃) significantly affects the performance of Sb₂S₃ thin film solar cells owing to its intrinsic quasi-one-dimensional crystal structure. Producing a Sb₂S₃ film with a [hk1] orientation is theoretically favorable for solar cell performance. However, it is a challenge to prepare a [hk1]-orientated Sb₂S₃ film, because Sb₂S₃ is prone to grow parallel to the substrates along the [hk0] orientation according to the minimum energy principle. Herein, guided by grain growth theory, we successfully control the orientation of a Sb₂S₃ film via modulating the grain growth process. Highly [hk1]-oriented Sb₂S₃ films on an CdS substrate can be obtained if the grain grows according to the normal grain growth model. Consequently, a solar cell device based on [hk1]-oriented Sb₂S₃ achieves a power conversion efficiency of 6.82%, performing better than that based on [hk0]-oriented Sb₂S₃ (6.27%). This research provides a new and effective method for orientation control of Sb₂S₃ for pursuing high performance Sb₂S₃ thin film solar cells.