Polyvinyl-based hole-transporting materials processed with non-destructive and green solvents for tin–lead perovskite solar cells and all-perovskite tandems

The widely used poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) in tin-lead (Sn-Pb) mixed perovskite solar cells limits scalable fabrication and operational stability of all-perovskite tandem solar cells. The aqueous-based and acidic PEDOT:PSS can penetrate the interconnection layer and degrade the underlying wide bandgap subcell. Here, we report a series of polyvinyl-based hole-transporting materials (PE-MPs) that are processable in non-aqueous green solvents. The deposition of PE-MPs is non-destructive to underlying perovskite stacks, and the resulting thin layer further protects the bottom subcell during the deposition of the Sn-Pb perovskite, providing a wide processing window for tandem fabrication. Through optimization of the monomer ratio, the best-performing PE-MP2 enables both efficient hole extraction and robust interfacial adhesion, greatly improving performance and stability of Sn-Pb devices and all-perovskite tandems. The Sn-Pb perovskite solar cell achieves a power conversion efficiency of 22.72%, and the all-perovskite tandem cell reaches 29.08% (certified 28.69%). More importantly, the all-perovskite tandems retain 90% of their initial efficiency after 570 hours of maximum power point tracking, ranking among the most efficient and stable all-perovskite tandems without PEDOT:PSS.