Monolithic Perovskite–Perovskite–Perovskite–Silicon Quadruple-Junction Tandem Solar Cell with Efficiency over 21%

Here, we demonstrate a proof-of-concept perovskite–perovskite–perovskite–silicon quadruple-junction tandem solar cell achieving a power conversion efficiency of 21.4% (steady state at 21.1%) and an open-circuit voltage of 4.01 V. To our knowledge, this is the first perovskite-based quadruple-junction tandem integrated on a silicon bottom cell, demonstrating the feasibility of a silicon-integrated four-junction architecture and establishing a baseline for future device optimization.