Scalable magnetic‐field‐assisted assembly of nanorod arrays with tunable orientation

Precise control of the orientation of anisotropic nanostructures is essential for exploiting their collective properties, yet achieving uniform alignment over large areas remains challenging. We report a magnetic‐field‐assisted colloidal assembly strategy for fabricating magnetite nanorod arrays with tunable orientation and thickness. Magnetic alignment of nanorods is facilitated by incorporating a high‐boiling‐point solvent, such as ethylene glycol, into the aqueous nanorod dispersion, thereby suppressing disturbances from flow convection and capillary forces. By adjusting the direction of the magnetic field, nanorod arrays with vertical, tilted, or horizontal configurations can be produced. To achieve scalability, the process is adapted to a moving substrate, ensuring uniform deposition of the aligned nanorod arrays across macroscopic areas. This versatile and scalable approach provides a robust platform for constructing nanorod arrays with programmable orientation and thickness, advancing next‐generation photonic, magnetic, and multifunctional devices.