Solution-processed chalcopyrite-perovskite tandem solar cells in bandgap-matched two- and four-terminal architectures

Solution-processed chalcopyrite and perovskite devices of various bandgaps are combined in four-and two-terminal mechanically-stacked tandem architectures. The excellent low-light performance of Cu(In,Ga)(S,Se)(2) and low-bandgap CuIn(S,Se)(2) cells and the high efficiency of novel NIR-transparent inverted perovskite cells with C-60/bis-C-60/ITO as electron transport layers, enabled stabilized two-and four-terminal tandemefficiencies up to 18.5% and 18.8%, respectively, which represent a new record for tandem devices with solution-processed chalcopyrite and perovskite absorbers.