Fabrication of opal-like thin films

A process is described for the fabrication of opal-like thin films by controlling a solid–liquid interface moving at an inclined glass substrate. A special airflow is adopted to control solvent evaporation. SEM images and photographs show that the films, composed of polystyrene spheres, are coloured, flat, uniform, packed multilayers, and are well arrayed over a large scale. The ordered domains range in size from 10 to 15?µm. The spheres in suspension crystallized, caused by an intense interaction between the spheres on the boundary between the suspension and the substrate. A wide photonic band gap is observed in the normal-incidence transmission spectra of the films fabricated by this method. Cracks and defects in the films are examined and discussed.