Advanced Sub‐Micron Pyramid Texture Enables Approximately 32% Efficiency in Perovskite/Silicon Tandem Solar Cells

ABSTRACT Textured bottom silicon solar cells assume a pivotal role and manifest considerable application promise in the fabrication of high‐performance perovskite/silicon tandem solar cells (PVSK/Si TSCs). In the state‐of‐the‐art perovskite/silicon tandem solar cells manufactured using spin‐coating processes, the bottom cells typically exhibit sub‐micron pyramid (SMP) textured morphologies that create numerous V‐shaped grooves between adjacent pyramids. These characteristic structural features simultaneously impair substrate wettability and increase surface roughness, presenting a major technical barrier to achieving high‐quality perovskite film deposition. Herein, leveraging isotropic etching principles, we propose a chemical polishing strategy to smooth the V‐shaped regions of SMP textured substrates. In contrast to directly depositing perovskite films on pristine SMP surfaces, this approach enhances not only the interfacial passivation between crystalline silicon and amorphous silicon but also the surface wettability of the silicon bottom cell, consequently augmenting the bottom cell performance and facilitating closer interfacial contact between perovskite films and the pyramid structures. Furthermore, the treated SMP surface with low roughness also promotes the growth of perovskite films, mitigating pore‐induced defects, alleviating lattice strain, and consequently enhancing film uniformity and crystalline quality. Ultimately, the power conversion efficiency (PCE) of wide‐bandgap PVSK/Si TSCs fabricated on the optimized SMP textures increased significantly from 30.04% to 31.83%, accompanied by substantial enhancements in open‐circuit voltage and short‐circuit current density, alongside negligible hysteresis behavior. This study pioneers a novel approach to achieve high‐efficiency tandem photovoltaic device by emphasizing the intrinsic properties of the silicon bottom cell, thereby offering fresh perspectives for advancing PVSK/Si tandem photovoltaic development.