Strategies and Pathways Toward Efficient Perovskite/Cu(In,Ga)Se₂ Tandem Solar Cells

Tandem solar cells (TSCs), which combine two highly efficient and spectrally complementary absorber materials, are considered an effective approach to surpass the efficiency limits of conventional single-junction cells while reducing thermal losses. Among them, perovskite/Cu(In,Ga)Se₂ (CIGS) tandem solar cells have attracted significant attention due to the complementary properties of CIGS and perovskite absorbers, as well as their advantages in flexibility and process compatibility, offering great potential in device performance, manufacturing cost, and practical applications. This review summarizes recent progress in improving the efficiency and stability of perovskite/CIGS tandem solar cells, covering both two-terminal (2T) and four-terminal (4T) architectures, as well as rigid and flexible configurations. We further discuss the key issues in perovskite, CIGS, and perovskite/CIGS tandem devices, including material properties, interconnection layers, optical management, and theoretical modeling. Finally, we highlight the critical challenges and future directions for advancing perovskite/CIGS tandem solar cell technology.