High-Performance Bifacial Perovskite/Silicon Double-Tandem Solar Cell

Bifacial technology aims to boost power conversion efficiency of solar cells by effectively harvesting the albedo sunlight reflected from the earth, which is typically uncollected in conventional solar cells. We propose an innovative three-terminal (3-T), four-junction perovskite/silicon bifacial tandem solar cell that leverages albedo to surpass the theoretical limits of the traditional monofacial tandem structures. The cell stacks two identical series-connected double-junction perovskite/silicon tandem cells with a common (middle) terminal such that the bottom tandem cell is integrated upside down to effectively harvest albedo. The albedo absorption in the bottom tandem cell linearly enhances the short-circuit current of the double-tandem structure; hence, it overcomes the classical current-matching limit in series-connected tandem solar cells. We use self-consistent optical/device simulations to investigate the design optimizations of the cell and compare its performance with a conventional tandem structure. With an optimal design, the cell exhibits a remarkable efficiency of 30%–36% (bifacial gain of 10%–30%) for the albedo range of 15%–45%. The 3-T cell design works optimally for any range of albedo that is in contrast with 2-T series-connected cell for which the optimal top cell thickness changes with the value of albedo. Moreover, the proposed cell is relatively less sensitive to the process variations in the perovskite layer thickness. With its remarkable efficiency, which increases linearly with albedo, the proposed cell can be highly attractive for emerging high-efficiency photovoltaic applications.