Photoresponsive photonic crystals constructed from azobenzene-grafted silica microspheres

Azobenzene compounds have been widely used in many fields and through their response to light they can be used to regulate the properties of ordered structures. In this paper, sub-micrometer colloidal SiO 2 spheres were prepared and azobenzene groups were grafted on the surface of SiO 2 microspheres. The SiO 2 microspheres grafted with azobenzene groups could self-assemble to form photosensitive photonic crystals, whose photonic bandgaps red-shifted as irradiated by UV light due to the structure change of the azobenzene groups.