Charge Transport in Chain of Nanoparticles

Abstract

We have bridged a pair of gold electrodes through chains and arrays of gold nanoparticles, coated with citrate molecules. We performed a systematic and comparative analysis of current-voltage (I − V ) characteristics for chains of nanoparticles, having variable length and configuration. The I − V characteristics I ∼ (V − V t ) ζ (with voltage threshold V t ≈ 0 and scaling exponent ζ ≈ 1) are attributed to hopping transport. Current fluctuations at a fixed bias voltage were observed, with a fluctuation amplitude proportional to the voltage applied. We found that the resistance of the bridge is not only a function of the number of molecular contacts, but also depends on the strength of the individual interactions between metal conductor and molecules. IntroductionDue to their optical and electronic properties, arrays of metallic nanoparticles (NPs) have attracted much attention in materials science. Charge transport through nanoparticle assemblies represents a fundamental process that controls their physical properties which are determined by the coupling and arrangement of individual NPs, and depend on their size, shape, and composition. Theory and experiments unveil that, at sufficiently low temperature below a threshold voltage V t , no current flows through the particle array, while above V t the current increases, according to the power law I ∼ (V − V t ) ζ with ζ = 1 in a one-dimensional (1D) and ranging between 5/3 and 2 in a two-dimensional (2D) array [1][2][3]. I denotes the current, V the voltage. Electronic coupling between individual particles is one of the fundamental parameters that governs charge transport in NP arrays. The coupling is influenced by inter-NP spacing and by stabilizer molecules capping the NPs. The inherent possibility of a switching between different molecular conformations represents one