Light trapping and guided mode enhancement in perovskite/Si tandem solar cells with embedded silicon nanowires

Energy loss at the interface between the subcells limits the efficiency of existing tandem solar cells. In this work, we propose a novel two-terminal perovskite/silicon tandem solar cell with vertically aligned silicon (Si) nanowires (NWs) incorporated between the two subcells. The sub-wavelength dimensions of the embedded Si NWs, grown on top of the Si bottom subcell, allow efficient light trapping and lead to guided resonant modes. Finite-difference time-domain (FDTD) analysis shows that, across the entire spectrum, these guided modes effectively couple the incident light between the subcells, reducing reflection losses in the interlayer and enhancing absorption in the underlying bottom c-Si cell. To evaluate the performance of the proposed tandem solar cell, we performed electrical simulations using the enhanced carrier generation profile obtained from the FDTD simulations. The proposed embedded NW tandem configuration yields 22.6% enhancement in short-circuit current density compared to conventional architectures, boosting the power conversion efficiency from 26.98% to 32.11%. These findings offer the necessary theoretical framework for experimentalists, providing a clear pathway towards realizing high-performance perovskite/Si tandem solar cells.