Challenges and perspectives toward wide-bandgap perovskite subcell in four-terminal all-perovskite tandem solar cells

Wide-bandgap (WBG) perovskite solar cells (PSCs) have gained remarkable interest owing to their latent applications in tandem solar cells (TSCs). Among them, four-terminal (4T) all-perovskite TSCs have received extensive attention as its do without need to consider current matching, surface roughness, and fabrication processes. However, low open-circuit voltage (V_OC) and efficiency of WBG PSCs obstacles their applications in 4T all-perovskite TSCs. Hence, this review firstly discussed the optimizing strategy in perovskite materials layer and properties. Specifically, we assessed the effect of composition, additive and interface engineering on the efficiency and V_OC of WBG PSCs. Secondly, the demonstrated applications of different passivation layers designing for intensifying the efficiency of WBG PSCs and 4T all-perovskite TSCs is discussed. Finally, we put forward three specific approaches for future research, in our view, which would offer appropriate guidance for the exploitation of highly efficient and stable 4T all-perovskite TSCs.