Geometries of Au nanoparticle-chains control their percolation in polymer

Gold nanoparticle (AuNP)-polymer composites have emerged as promising candidates for flexible electronics due to their super-high stretchability and metal-like conductivity. Their percolation threshold is, however, much higher than that of 1D carbon nanotubes or silver nanowires. A practical and appealing solution is to assemble AuNPs into 1D quasi-nanowires via the van der Waals interaction. In this letter, electron tunneling is incorporated into the theory of traditional composites to explore the percolation of these nanocomposites. The geometries of AuNP-chains are found to play a key role in determining the effect of electron tunneling and thus the overall percolation behavior. Small and/or short AuNP-chains yield the substantial tunneling effect, leading to the rapid growth in conductivity across a transition zone where the conductivity mechanism transfers from electron tunneling to contact conductance. This unique feature agrees with experimental observation but cannot be characterized directly by existing theories. Published by AIP Publishing.