Fabricating High‐Efficiency Sb₂(S,Se)₃ Solar Cells by Novel Additive‐Assisted Longitudinal Component Engineering

Abstract Antimony selenosulfide (Sb₂(S,Se)₃) solar cells have achieved an efficiency of over 10.0%. However, the uncontrollable hydrothermal process makes preparing high‐quality Sb₂(S,Se)₃ thin films a bottleneck for efficient Sb₂(S,Se)₃ solar cell. To address this problem, triethanolamine (TEA) additive is innovatively utilized to regulate the reaction kinetic process of Sb₂(S,Se)₃ thin films in this work. The results show that TEA chelator can realize the time‐domain control of the reaction process, optimizing the Se/(S+Se) elemental distribution of Sb₂(S,Se)₃ thin film and shrinking the bandgap offset of Sb₂(S,Se)₃ thin film. Meanwhile, the (021) and (061) crystal orientation of Sb₂(S,Se)₃ thin film are enhanced and the harmful V_Se1 defects in Sb₂(S,Se)₃ solar cells are passivated. Interestingly, a uniform back surface gradient for Sb₂(S,Se)₃ thin film is formed to reduce the minority carrier recombination at the back contact, increase the photocurrent and decrease the diode current of Sb₂(S,Se)₃ solar cells. Finally, the J_sc and FF of Sb₂(S,Se)₃ solar cells are significantly improved by 8.6% and 5.5% respectively, and the open‐circuit voltage deficit of the device is reduced by 44 mV, which leads to an efficiency of 9.94% which is the highest values of Sb₂(S,Se)₃ solar cells by sodium selenosulfate system.