Efficient Se‐Rich Sb₂Se₃/CdS Planar Heterojunction Solar Cells by Sequential Processing: Control and Influence of Se Content

Quasi‐1D chalcogenides are under the spotlight due to their unique properties for several technological applications including computing, photonic, sensing, and energy conversion. In particular, antimony chalcogenides have recently experienced incredible progresses as emerging photovoltaic materials. Herein, the fabrication by a sequential process of Sb₂Se₃ solar cells is addressed, and the annealing temperature is found to be the main parameter controlling the composition of the Se‐rich absorbers. Building on this, a systematic study of the evolution of the optoelectronic parameters of the solar cells as a function of the Se excess is presented together with a thorough characterization of the devices that sheds light on their main limiting factors. A record power conversion efficiency of 5.7% is achieved, the highest reported value using reactive annealing on a metallic precursor for this material.