Two‐Terminal Sb ₂ S ₃ /PbS‐QDs Tandem Solar Cells with Over 12% Certificated Efficiency Utilizing Bidentate Additive Strategy

Abstract As a wide‐bandgap light‐harvesting material, antimony sulfide (Sb 2 S 3 ) is considered one of the optimal candidates for top cells in tandem photovoltaics. However, the development of Sb 2 S 3 ‐based two‐terminal (2T) tandem solar cells has been relatively slow due to the limited performance of Sb 2 S 3 single‐junction devices. Because of the complex deep defects, high‐quality growth of Sb 2 S 3 thin films plays a crucial role in Sb 2 S 3 single‐junction devices and 2T tandem devices. In this study, we introduced a bidentate coupling small molecule additive, sodium thioglycolate (ST), into the precursor solution to regulate the nucleation and growth process. Experimental results demonstrated that ST formed a synergistic complexion with Sb 3+ via ‐SH and ‐COO − ligands, which effectively inhibited the homogeneous nucleation in the precursor solution and stabilized the growth process of Sb 2 S 3 thin films. As a result, the ST‐regulated Sb 2 S 3 (ST‐Sb 2 S 3 ) achieved a champion power conversion efficiency (PCE) of 8.36%. The corresponding Sb 2 S 3 /PbS‐quantum‐dots (PbS‐QDs) 2T tandem devices obtained a record certified efficiency of 12.09%. This work presents a novel additive strategy for film growth and further demonstrates the broad prospects of Sb 2 S 3 ‐based 2T tandem devices.