Nature Energy, Published online: 26 May 2026; doi:10.1038/s41560-026-02077-8

Low-bandgap tin–lead perovskites can boost solar cell efficiency but degrade quickly due to tin oxidation. Here the authors add proton-scavenging additives that stabilize inks for over 300 days, enabling 24.06% single cells and 29.56% certified tandem efficiency.