Preparation of opal films for optical properties research.

Opal films made of 205, 230, 270, 290 nm monodisperse polystyrene (PS) microsphere were prepared with vertical self-assembly method. The opal films show different colours in natural light and the light of halogen tungsten lamp. The PS microsphere in opal films arranged as well-ordered hexagonal close-packed structure on top view, and face-centred cubic structure on cross-section. The testing values of band gap positions of the opal films are consistent with calculating values, and can be described with Bragg's law. The band gap positions of the opal films can be modulated by changing the distance of the neighbouring (111) planes. [ABSTRACT FROM AUTHOR]