Infrared Plasmonics via Self-Organized Anisotropic Wrinkling of Au/PDMS Nanoarrays

Polydimethylsiloxane (PDMS) templates are nanopatterned over large areas to form uniaxial wrinkles by air plasma treatment on prestretched samples. Ripple-like structures with tunable height/width aspect ratio are so achieved. The anisotropic uniaxial PDMS modulations represent an ideal platform for the confinement of plasmonic nanowire (NW) arrays by grazing angle Au thermal deposition. This self-organized fabrication method is suitable to be scaled to the industrial level as a single step maskless process. The flexible NW arrays show monodisperse width distribution and exhibit strongly dichroic optical properties. Localized surface plasmon resonances (LSPR) of dipolar and multipolar character are excited when light is linearly polarized orthogonally to the NW major axis. The LSPR wavelength can be easily tuned across a remarkably large spectral range from 600 to 1200 nm by engineering the NW width and the PDMS ripple morphology. The PDMS/Au NW nanocomposite material also shows relevant performance as a transparent flexible electrode with sheet resistance on the order of 15 Omega/sq, a figure of merit which is competitive with the best transparent conductive oxides.