Modification of spontaneous emission of solid-state organic molecules embedded in photonic crystals

Highly monodisperse colloidal silica spheres in submicron size were synthesized by a chemical method and close-packed face-centered-cubic photonic crystals (PCs) were prepared. Tris (8-hydroxyquinoline) aluminum (Alq3) has been in-filled in this structure to investigate the photonic band gap effect on the spontaneous emission. Because of the overlap of the photonic band gap and the photoluminescence (PL) band of Alq3, both suppression and enhancement in the photoluminescence of the organic molecules were observed. The PL of Alq3 molecules in PCs exhibited a small blue shift compared with the ones deposited on glass slide, which was believed to arise from the reduced interaction between organic molecules.