Fabrication of colloidal crystal heterostructures by a room temperature floating self-assembly method

Photonic crystal heterostructures were fabricated through a room temperature floating self-assembly (RTFSA) method recently developed by our research group. Applying this method, opal colloidal crystal heterostructures of several square centimeters in area were fabricated within tens of minutes without special facilities, and a heterostructure composed of a PS opal and a TiO2 inverse opal crystal films was fabricated. SEM image of the PS opal–TiO2 inverse opal heterostructure showed the ordered growth of the top opal film of the heterostructure was hardly disturbed by the cracks in the TiO2 inverse opal film. The UV–vis transmission spectra indicated that the photonic heterostructures had two photonic-band gaps, and the relative position of two photonic-band gaps can be controlled by the size of PS microspheres used to fabricated the photonic heterostructures.