Photonic pseudo-gap-based modification of photoluminescence from CdS nanocrystal satellites around polymer microspheres in a photonic crystal

We report the combination of microsphere self-organization to form a photonic crystal, providing spectrally and angularly dependent electromagnetic structural resonances; with nanocrystal growth in situ on microsphere surfaces, providing optical functionalization with spectral control achieved through the quantum size effect. We demonstrate this material system using CdS nanocrystals coating the surfaces of poly(methyl methacrylate)-poly(methacrylic acid) (PMMA-PMAA) micrometer spheres. The in situ synthesis of the CdS nanocrystals on the surface of the PMMA/PMAA microspheres preserves the propensity of the hybrid microspheres to form ordered colloid arrays. Luminescence from surface states ensures that light is emitted at energies significantly below the absorption edge of the emitting species. Transmission and photoluminescence measurements reveal the interaction of the photonic stop band with photoluminescence from the nanocrystals.