One hour road to high-quality arrays of gold nanoparticles coated with organic ligands

Abstract

Arrays of gold nanoparticles (AuNP) covered with organic molecules have promising applications in biology, electronics, energy, and fundamental physics, among other areas. Here we consider different approaches to synthesise, coat the AuNP with a ligand and to induce their self-assembly into a network within one hour. Arrays formed from aqueous AuNP are stabilised with small ions or alkane chains of 8 to 18 carbons long as the assembly is induced. Alternatively, the AuNP are exchanged to an organic solvent and covered with alkanethiols or oleylamine before the array formation. Beside the length of the ligand, the network morphology and electronic properties are highly affected by the deposition conditions. By using a solid-state exchange strategy, we alternately replaced the ligand on the AuNP with long and short alkanethiols, for which the change of the network's resistance appears reversible. Using this ligand exchanged strategy, we replaced a commercially available alkanethiol with a bespoke naphthalene diimide, resulting in improved conductivity of the networks and their stability in air. Crucially, this simple, rapid, and versatile AuNP–organic network formation offers a platform to the scientific community to investigate the physical and chemical properties of complex molecules.