Synthesis of Stable SnI<sub>2</sub>·<i>x</i>DMSO Adducts toward Efficient Tin–Lead Perovskite Solar Cells
Zhenkai Zhu, Ciyu Ge, Dayu Liu, Qi Xu, Yongxin Zhu, Xuke Yang, Chong Dong, Xinzhi Zu, Shuwen Yan, Jun Wang, Zeyu Zhang, Shuping Pang, Juan Du, Long Hu, Dewei Chu, Ling Xu, Haisheng Song, Luying Li, Ying Zhou, Chao Chen, Jiang Tang
Abstract
Sn–Pb narrow-bandgap perovskites are indispensable for achieving highly efficient all-perovskite tandem solar cells as bottom subcells. However, facile oxidation of Sn 2+ into Sn 4+ leads to the poor precursor stability, which largely hinders the development of Sn–Pb perovskite solar cells (PSCs). Herein, we present a novel strategy to synthesize SnI 2 · x DMSO intermedium adducts in situ utilizing a mild one-to-one reaction between molecular SnI 4 and metallic Sn. This approach avoids the formation of low-coordinated SnI 2 · x DMSO clusters ( x ≤ 2), yielding highly coordinated SnI 2 · x DMSO ( x = 3) adducts with enhanced antioxidation ability. The resultant precursor showed outstanding stability and reproducibility. The aged precursor for 7 days maintains its initial properties. Consequently, the resulting Sn–Pb PSCs deliver an impressive efficiency of 22.64% and retain ∼ 90% of their initial value after maximum power point operation under simulated one-sun illumination in air for 530 h under encapsulation. Our finding provides an effective pathway to enhance the intrinsic antioxidant capacity of Sn 2+ in perovskite precursors, paving a way for the development of efficient and reproducible Sn–Pb PSCs.