Controlled assembly of Au nanorods into 1D architectures by electric field assisted deposition

Abstract

The assembly of Au nanorods of average size 14 × 42 nm was investigated by electric field assisted deposition. The nanorods displayed a rich assembly behavior with formation of one dimensional (1D) architectures under specific experimental conditions. The assembly process was found to be dependent on both the intensity of the applied electric field and the frequency, in contrast to what was expected for metallic particles. A theoretical model based on interpretation of nanorods as core–shell entities was proposed in order to explain the observed behavior. As a result the overall deposition process was represented by a contour plot, where the force acting on the nanorods was displayed as a function of both the electric field and frequency. In particular, an area of the contour plot was identified where the deposition process was driven by generation of localized “hot spots” of high E-field magnitude, leading to formation of well-aligned 1D nanorod architectures bridging the electrode gaps. Electrical characterization showed that 1D architectures displayed tunneling behavior across the inter-nanorod gap. The controlled organization of nanorods into 1D architectures presents opportunities for electronic, sensing and plasmonic applications.