Diffusion‐Driven Macromolecular Self‐Organization Enables Conformal Perovskite/Silicon Tandems

ABSTRACT 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‐C 12 ) that simultaneously regulates perovskite crystallization and mitigates interfacial defects. Interfacial‐energy gradients created during solvent evaporation impose a thermodynamic driving force that expels ZnPc‐C 12 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.