Electric‐Field‐Assisted Spin Coating: A New Process for Adjusting Crystallization of Perovskite Thin Films

Electric‐field‐assisted spin coating is introduced as a vectorial wet‐film processing strategy for influencing methylammonium lead iodide () crystallization during hydrodynamic thinning and solvent evaporation. films were deposited onto grounded substrates under perpendicular electric fields of 0–8 kV . The field was applied during a 25 s spin‐coating/antisolvent interval and removed before annealing. X‐ray diffraction (XRD) identified tetragonal as the dominant phase and field‐dependent changes in texture, peak displacement, microstrain, and coherent domain size were observed. Scanning electron microscopy (SEM) showed grain coarsening, as the mean grain diameter increased from 128.8 nm for the 0 kV condition to 303.9 nm at 2 kV . The largest ‐family texture enhancement and low‐angle peak displacement occurred at 6 kV , while coherent‐domain size increased monotonically across the field‐assisted series, reaching 190.5 nm at 8 kV . A 2 kV specimen exhibited pronounced out‐of‐plane texture, showing that the deposition platform can access a strong texture‐selection pathway. These results show that an electric field applied during spin casting acts as a charge‐selective perturbation involving a vector force, and decouples grain growth, orientation, lattice displacement, and crystallographic coherence during film formation.