Negative-pressure sulfurization of antimony sulfide thin films for generating a record open-circuit voltage of 805 mV in solar cell applications

Abstract

Antimony sulfide (Sb₂S₃) has excellent stability and a suitable bandgap for top cell materials in tandem solar cells, attracting intense attention for application in solar cells. However, the complex and unconventional deep-level defects in the quasi-one-dimensional crystal structure of Sb₂S₃ cause non-radiative recombination, leading to a large open-circuit voltage deficit (V_OCD) and posing a significant challenge to improving power conversion efficiency (PCE). This study developed a sulfurization approach at a negative-pressure atmosphere of sulfur (S) for Sb₂S₃ films. The method could compensate for the S loss in the annealing of Sb₂S₃ films, transferring them into S-rich states and reducing recombination losses associated with a sulfur vacancy (V_S). Simultaneously, the annealing process induced Sb₂S₃ crystallization with preferential [hk1] orientation, benefiting carrier transport. The reduced deep-level defect and optimized microcrystal orientation enabled a record open-circuit voltage (V_OC) of 805 mV in Sb₂S₃ solar cells. Therefore, this study provided a convenient approach for passivating point defects in metal chalcogenide films and improving V_OC in solar cells.