Ferromagnetic–Electronic Coupling Strategy for Enhancing Operational Stability of Planar Perovskite Solar Cells toward Magnetron Co‐Sputtered Iron‐Doped Zinc‐Tin‐Oxide Ferroelectric Electron Transport Layers

ABSTRACT In recent years, research on the ferroelectric coupling photovoltaic effect has gained remarkable advances in enhancing the efficiency and stability of perovskite solar cells (PSCs). Herein, Fe‐doped Zn ₂ SnO ₄ ferroelectric thin films were produced at room temperature via the magnetron co‐sputtering method and employed as electron transport layers in planar based PSCs. The impact of various polarization directions on photovoltaic performance has been extensively examined. Diamagnetic Zn ₂ SnO ₄ thin films were effectively endowed with ferromagnetic characteristics by doping with iron as a “hard ferromagnetic element”. The incorporation of iron enhances spontaneous dipole polarization and reduces defects at the perovskite/ETL interface, leading to an impressive efficiency of over 23% with a perpendicular magnetic field, compared to 22% for control. The cells also exhibited remarkable operational stability, maintaining 97% after 600 h under continuous illumination at 85°C, and 91% of initial efficiency after 1000 h under a relative humidity environment. This work emphasizes the utilization of ferromagnetic electron transport layers for controlling spontaneous polarization and altering carrier dynamics in perovskite, which is crucial for achieving highly efficient PSCs with improved operational stability.