Optimization of Perovskite‐Silicon Alloy Dual‐Junction Architectures for Next‐Generation Solar Cells

This study investigates the enhancement of silicon‐based photovoltaic performance through bandgap engineering using silicon alloy materials. The Shockley–Queisser (SQ) limit defines the maximum efficiency for unijunction solar cells and restricts conventional crystalline silicon devices due to their fixed bandgap of 1.12 eV. To alleviate this constraint, this work proposes using a germanium‐based silicon alloy, SiGe, which enables tunable bandgaps that improve spectral response and reduce carrier thermalization losses. SCAPS‐1D is utilized to perform numerical simulations and compare the optoelectronic characteristics of a conventional silicon device with those of engineered silicon alloy structures. The optimized silicon alloy solar cell achieved an open circuit voltage of 0.7368 V and a power conversion efficiency (PCE) of 28.52%, representing a notable improvement over the 24.59% PCE obtained for the standard silicon cell. Furthermore, design and analysis of a two‐terminal tandem configuration integrating a wide‐bandgap perovskite top cell with a silicon alloy bottom subcell are carried out. The tandem architecture demonstrated superior spectral utilization of both high‐ and low‐energy photons, resulting in a simulated overall PCE exceeding 42%, thereby surpassing the single‐junction SQ limit. These findings highlight the significant promise of bandgap‐engineered silicon alloys, particularly when incorporated into perovskite/silicon tandem configurations, for the development of next‐generation high‐efficiency photovoltaic technologies.