A cascade-type electron extraction design for efficient low-bandgap perovskite solar cells based on a conventional structure with suppressed open-circuit voltage loss

A cascade-type and energy-level-aligned electron transport layer of ZnO/SnO 2 /C 60 -SAM is beneficial for suppressed charge recombination and improved charge extraction in low-bandgap perovskite solar cells, resulting in a reduced V oc loss.