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Three-dimensional assemblies of 230 nm polystyrene (PS) colloidal particles were prepared on the suspension surface by evaporating the water in which the particles were suspended. The assembled colloidal particles were then transferred from the water surface onto a glass substrate by simple evaporation and sedimentation. In this study, we analyzed the structures of the colloidal assemblies formed at evaporation temperatures of 30, 40, 60, and 90°C. At 30°C, the rate of particle sedimentation is faster than the rate of crystallization on the water surface. Consequently, the PS particles randomly stack on the glass substrate before forming nuclei on the water surface. At higher evaporation temperatures, on the other hand, the rate of crystallization on the water surface exceeds the sedimentation rate, leading to an improvement in the quality of the resulting colloidal crystal. However, crystalline quality diminishes at evaporation temperatures greater than 60°C because the high crystal growth rate leads to the formation of defects. As a result, there exists an optimum evaporation temperature that yields the highest quality crystals. Importantly, this novel process enables the rapid (within 1 h) fabrication of large-scale three-dimensional colloidal crystals.

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A dramatic increase in the photostability of a blue‐light‐emitting polymer, poly(9,9‐dioctylfluorene), was achieved by the addition of 5–10 nm gold nanoparticles. The optical absorption band of the gold nanoparticles was tuned to resonate the triplet exciton ground state bandgap energy of the polymer. Photo‐oxidation rate of poly(9,9‐dioctylfluorene) was effectively reduced by doping the polymer with very small amounts (≈10−6–10−5 volume fraction) of the gold nanoparticles.Retarded photo‐oxidation in PDOF nanocomposite films with various doped gold nanoparticles.magnified imageRetarded photo‐oxidation in PDOF nanocomposite films with various doped gold nanoparticles.