Diffusion-Driven Macromolecular Self-Organization Enables Conformal Perovskite/Silicon Tandems.

Industrial deployment of perovskite/silicon tandem solar cells is limited by the difficulty of forming thick, defect-controlled wide-bandgap (WBG) perovskite layers that conformally coat micron-textured silicon while retaining interfacial passivation. Here, we introduce a diffusion-driven macromolecular passivation strategy (DMPS) employing a π-extended zinc phthalocyanine derivative (ZnPc-C12) that simultaneously regulates perovskite crystallization and mitigates interfacial defects. Interfacial-energy gradients created during solvent evaporation impose a thermodynamic driving force that expels ZnPc-C12 from the bulk toward both interfaces, establishing dual-interface passivation and uniform 1.5 µm WBG perovskite films on industrial Czochralski silicon heterojunctions. The resulting single-junction devices achieve 24.26% power-conversion efficiency, while monolithic tandems deliver 34.26% (certified 33.83%) efficiency and > 90% retention after 800 h of continuous operation. DMPS provides a general and scalable pathway for integrating defect-controlled perovskite absorbers into textured silicon architectures, advancing the manufacturability of next-generation film-on-wafer tandem photovoltaics.