Directed assembly of suspended nanowires assisted by topographically patterned surfaces of n-paraffin

Abstract

Herein, we present a method to generate site-selective assembly of suspended silver nanowires (Ag NWs) in large area by using hydrophobic patterned surfaces of n-paraffin. A thin layer of n-paraffin (eicosane, C 20 H 42 ) was prepared on the desired substrates. Then, the microcontact printing technique utilizing prism-type patterns of poly(dimethyl siloxane) (PDMS) was applied on the eicosane layer to generate hydrophobic patterns on the substrates. Ag NWs were synthesized through a polyol process with poly(vinyl pyrrolidone) (PVP) and dispersed in methanol. After Ag NWs suspension was introduced on the patterns of n-paraffin, we found that complete evaporation of the suspension solvent resulted in the selective assembly of Ag NWs in troughs of the patterns due to the synergetic effect of both surface energy difference and height contrast. Consequentially, the large-area assembly of Ag NWs was achieved on the substrates by thermally removing the eicosane patterns. Moreover, the optical and electrical properties of the Ag NWs assembly were characterized for applications as transparent electrical conductors.