Embedding of a gold nanofin array in a polymer film to create transparent, flexible and anisotropic electrodes

A facile fabrication method of transparent, conductive and flexible films was achieved by embedding an Au nanofin array into a polymer film. The Au nanofin was prepared by Au sputtering on the grating surface and successive dry etching. The main structural feature of the Au nanofin electrodes is its vertical alignment despite the width of less than 100 nm. Surprisingly, high aspect ratios of height and width, which provide a wide cross sectional effect, are obtained with the vertically disposed metal fins. The Au nanofin film exhibited anisotropic electrical conductivity in a parallel direction with the Au nanofins and its transmittance under visible light and sheet resistance were ca. 81% and 43 Ω/□, respectively, which are comparable to those of a commercial ITO sheet. Moreover, the Au nanofin film could be bent repeatedly with a curvature radius of 3.5 mm without losing its high and anisotropic conductivity. The Au nanofin films can be applied in the electrodes of solar batteries and in see-through displays with high flexibility.