Solution-processible fabrication of large-area patterned and unpatterned gold nanostructures.

Solution-processible fabrication of large-area plasmonic nanostructures using colloidal gold nanoparticles has proven its advantages not only in its simplicity, low cost, high speed, and high flexibility, but also in the realization of some nanoscale optoelectronic devices that cannot be achieved by conventional methods. We demonstrate in this paper a variety of techniques for fabricating different plasmonic nanostructures using solution-processible gold nanoparticles and differently designed annealing processes. Using interference lithography and low- (<300 degrees Celsius) or high-temperature (>350 degrees Celsius) annealing processes, we succeeded in fabricating high-quality one- and two-dimensional metallic photonic crystals which exhibit promising optical responses for the exploration of new optoelectronic devices. Furthermore, using direct high-temperature (>350 degrees Celsius) annealing of a thin film of colloidal gold nanoparticles, we succeeded in fabricating large-area unpatterned isolated gold nano-island structures with a mean diameter tunable from about 35 to 100 nm and a mean height from 20 to 70 nm by controlling the concentration of the gold nanoparticle colloid, the annealing temperature, and the surface properties of the substrate. The corresponding optical response is thus tunable in the visible spectral range by changing the fabrication parameters. This introduces a new lithography-free technique for the preparation of gold nanostructures. These flexible fabrication techniques constitute a systematic route for the realization of plasmonic nanodevices.