We report the observation of inhibited spontaneous emission of organic dye rhodamine 6G infiltrated in a polymer replica of synthetic opal as a photonic crystal. The morphology-dependent resonances, superimposed on the broadband emission of rhodamine 6G due to spherical wavelength-sized microcavity enhancement of dye emission, have also been observed.

Spectral narrowing of photoluminescence (PL) and evolution of sharp emission lines upon optical excitation have been observed in opals made of SiO2 spheres infiltrated with conducting polymers such as OOPPV and MDDOPPV and also fluorescent dyes such as rhodamine 6G, NK-3483, and coumarin 120. Their emission properties are dependent on the sort of the opal and the solvents used for infiltration. With increasing optical excitation intensity, spectral narrowing and evolution of sharp lines have been observed in the green opal infiltrated with OOPPV, MDDOPPV, or rhodamine 6G but not in the infiltrated red and purple opals. With a solvent having a refractive index similar to that of SiO2, the evolution of the sharp emission lines is greatly suppressed and the lines exhibit a blueshift with decreasing refractive index. In NK-3483 and coumarin 120 which show red and purple PL, respectively, evolution of sharp lines is observed when they were infiltrated in red and purple opals, respectively, but not in other opals. These results are discussed in terms of amplified spontaneous emission and multimode lasing due to optical feedback in the opal matrix with a periodic structure.

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A highly luminescent disubstituted polyacetylene, poly͑1-phenyl-2-p-n-butylphenylacetylene͒ (PDPA-nBu), and its blend with a poorly luminescent monosubstituted polyacetylene, poly͑1o-trimethylsilylphenylacetylene͒ (PPA-oSiMe 3 ), are studied by time-resolved photoluminescence ͑PL͒ spectroscopy. In pure PDPA-nBu, PL intensity at short wavelength decays faster than that at long wavelength, whereas PL spectra exhibit a dynamic Stokes shift to longer wavelengths with time. In blends of PDPA-nBu/PPA-oSiMe 3 , only PL originating from PDPA-nBu is observed, without contribution from PPA-oSiMe 3 . The PL lifetime drastically decreases upon mixing a small amount of PPA-oSiMe 3 in PDPA-nBu. The PL characteristics of pure PDPA-nBu and its blend with PPA-oSiMe 3 are discussed in terms of lattice/vibrational relaxation of the excitonic state and exciton migration.

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