Controlled tuning of the stop band of colloidal photonic crystals by thermal annealing

Colloidal photonic crystals, which the stop band could be tuned by thermal annealing, were fabricated using monodisperse vinyl functionalized silica spheres. The samples diffract light following Bragg’s law combined with Snell’s law. The stop band had more than 25% blue shift with the increase of the annealing temperature from 60 to 570 °C. In addition, the annealing temperature and the Bragg peak values have a linear relationship in the 140–450 °C range. Moreover, the thermally adjusted tuning process was irreversible. The effects provide a simple and controllable method for tuning the optical properties of colloidal photonic crystals.