We demonstrated perovskite–Cu(In,Ga)Se2 (CIGS) tandem solar cells in which the perovskite top absorber is deposited by coevaporation, enabling highly uniform film formation on rough CIGS bottom cells. In addition, we introduced a compact tin oxide buffer layer on the zinc oxide surface, effectively preventing the detrimental Lewis acid–base reaction with the perovskite. A certified power conversion efficiency of 24.5% (1 cm2 aperture area) is achieved from the resulting monolithic perovskite–CIGS tandems. This work establishes a scalable vacuum-based route for delivering high-efficiency perovskite–CIGS tandem photovoltaics.
Li et al. (2026) studied this question.