Nature Energy, Published online: 05 August 2026; doi:10.1038/s41560-026-02125-3

The performance of perovskite/Cu(In,Ga)Se2 tandem solar cells is limited by optical and electronic losses at the interfaces between layers. By engineering two of these interfaces, Zeng, Wang, Tang et al. achieve a certified efficiency of 30.57% and improved device stability.