Metal halide perovskite tandem and multiple-junction photovoltaics

Metal halide perovskite-based solar cells have attracted considerable attention in recent years owing to their inexpensive and easy fabrication and rapidly increasing efficiencies, which already match those of the industrially dominant multi-crystalline silicon. The incorporation of perovskite absorber materials into multiple (multi-) junction cells could potentially allow us to go well beyond silicon-based technology and reach even higher power conversion efficiencies. Layering multiple solar-absorber junctions on top of each other enables the absorption of different regions of the solar spectrum, so that more energy can be extracted from sunlight. The possibility of tuning the bandgap of perovskite materials over a wide range, along with the ability to generate high open-circuit voltages from wide-bandgap absorbers, make perovskites ideal candidates. Perovskites can be used in combination with or as a substitute for silicon in photovoltaic technologies already in use and can be assembled in hybrid tandem architectures or layered in all-perovskite multi-junction cells. In this Review, we discuss opportunities for perovskite multi-junction cells, explore the progress made so far, describe the theoretical possibilities and discuss perspectives and challenges for the future of this emergent technology.