Effect of Energy‐driven Molecular Precursor Decomposition on the Crystal Orientation of Antimony Selenide Film and Solar Cell Efficiency

Abstract Antimony selenide (Sb 2 Se 3 ) consists of 1D (Sb 4 Se 6 ) n ribbons, along which the carriers exhibit high transport efficiency. By adjusting the deposition parameters of vacuum‐deposited methods, such as evaporation temperature, chamber pressure, and vapor concentration, it is possible to grow the (Sb 4 Se 6 ) n ribbons vertically or highly inclined towards the substrate, resulting in films with [ hk 1] orientation. However, the specific mechanisms by which these deposition parameters affect the orientation of thin films require a deeper understanding. Herein, a molecular beam epitaxy technique is developed for the preparation of highly [ hk 1]‐oriented Sb 2 Se 3 films, and the effect of evaporation parameters on the film orientation is investigated. It is found that the evaporation temperature can affect the decomposition degree of Sb 2 Se 3 , which in turn determines the vapor composition and film orientation. Additionally, the decomposition of Sb 2 Se 3 related to evaporation temperature leads to significant changes in the elemental composition of the film, thereby passivating deep‐level defects under Se‐rich conditions. Consequently, the Sb 2 Se 3 films with highly [ hk 1] orientation achieve a power conversion efficiency of 8.42% for the solar cells. This study provides new insights into the control of orientation in antimony‐based chalcogenide films and points out new directions for improving the photovoltaic performance of solar cells.