Enhanced Interfacial Contact Enables Stable MA‐free Perovskite–Silicon Tandem Photovoltaics

ABSTRACT Despite rapid efficiency gains in perovskite–silicon tandem solar cells (P/Si TSCs), state‐of‐the‐art devices continue to rely heavily on methylammonium (MA)‐containing wide‐bandgap (WBG) perovskites, where MA facilitates crystallization but intrinsically accelerates thermal degradation and halide segregation. Achieving efficient, thick (>700 nm), MA‐free WBG perovskites on textured silicon remains an unresolved challenge. Here, a coordination network coupled with π–π stacking work is designed to synchronize kinetics in MA‐free FACs‐based perovskite and promote conformal integration with textured silicon. A compact heterocyclic molecule simultaneously forms hydrogen‐bonds with FA cations and coordinates with the Pb–I framework, while engaging in π–π stacking with underlying self‐assembled monolayers. This multi‐interaction synergy regulates nucleation and drives vertical crystal growth, yielding void‐free buried interfaces and columnar grains spanning the full film thickness. The reconstructed interface exhibits reduced trap density and favorable energy‐level alignment, enabling efficient hole extraction and suppressing electron back‐transport and mixed‐halide segregation. Consequently, the 1.68 eV MA‐free perovskite device achieves an efficiency of 24.04%. Monolithic P/Si TSCs reach 33.04% efficiency, maintaining >90% initial performance after 1600 h of maximum power point tracking. This work establishes a generalizable strategy to decoupling crystallization control from MA incorporation, enabling durable and high‐performance tandem photovoltaics.