Theoretical Analysis of Perovskite/Ultrathin Silicon Tandem Solar Cells with Ag Nanocone Plasmonics

Perovskite and ultrathin single-crystalline silicon can form flexible tandem solar cells, achieving enhanced utilization of solar spectrum through the combination of wide-bandgap perovskite and narrow-bandgap silicon materials. However, as the thickness of light-absorbing layers decreases, current mismatch induced by optical mismatch has become a critical bottleneck constraining the efficiency improvement of ultrathin tandem cells. This study systematically investigates the optical absorption enhancement mechanisms of Ag nanocone plasmonic structures in tandem solar cells through theoretical analysis and numerical simulations. The results demonstrate that for tandem cells with ultrathin absorber layers in both top and bottom subcells, positional optimization of plasmonic structures can significantly improve light absorption efficiency via synergistic effects of tip-field enhancement and light scattering. For dual-bandgap ultrathin tandem cells, the optical absorption spectrum is divided into three characteristic regions. Inverted placement of Ag nanocone arrays within the intermediate layer enables finer regulation of light absorption in both top and bottom subcells, thereby effectively addressing optical mismatch issues. This research provides a theoretical foundation and technical guidance for designing high-efficiency, low-cost, flexible, and lightweight perovskite/silicon tandem solar cells.