Optical Properties of Nanoparticle-Based Metallodielectric Inverse Opals


  • F.C. acknowledges support from the Australian Research Council and the Victorian State Government Science, Technology and Innovation initiative, D.W. from the MPI Interface Section (H. Möhwald), J.L. and C.T.C. from the Hong Kong RGC through HKUST6138/00P, V.S. and L.M.L. from the Spanish Xunta de Galicia and Ministerio de Ciencia y Tecnología, and S.R. from the DFG Photonics Program.


Metallodielectric inverse opals were prepared by co-crystallizing silica-coated gold nanoparticles and polymer spheres, followed by removal of the crystal template. The inverse opals exhibit a distinct reflectance peak, which results from Bragg diffraction due to the highly ordered 3D macroporous structure. Photonic band-structure calculations indicate that the characteristic reflectance peaks observed are signatures of the directional gap at the L point. It is demonstrated that the optical properties (the position and magnitude of the electromagnetic bandgaps) of the gold–silica nanocomposite inverse opals can be engineered by varying the nanoparticle morphology (core size and shell thickness) and/or the nanoparticle volume-filling ratio of the composite. The use of metallodielectric nanoparticles to form inverse opals offers a versatile approach to prepare photonic materials that may exhibit absolute bandgaps.