Light Management in Monolithic Perovskite/Silicon Tandem Solar Cells

Perovskite/silicon tandem solar cells (TSCs), especially two-terminal, with a record efficiency of 28% already realized, present great potential as low-cost and efficient substitutes for dominant silicon photovoltaics. Achieving efficiencies exceeding 30% is quite realistic, as indicated by extensive optical simulations. Super light management in monolithic perovskite/silicon TSCs is one of the prerequisites to make this a reality. In this Review, various forms of optical losses, such as reflection loss, parasitic absorption, and current mismatch, are analyzed systematically to provide a better understanding of the performance of perovskite/silicon TSCs. Particularly, a simple refractive index matching rule derived from the Fresnel equation is proposed as a basis for material selection and device design. Meanwhile, an overview of the current strategies and challenges in monolithic perovskite/silicon TSCs is provided, comprising bandgap engineering of perovskites and light trapping methods, aiming to provide guidance for further improvement of tandem devices.