Characterization of thiol-functionalized oligo(phenylene-ethynylene)-protected Au nanoparticles by scanning tunneling microscopy and spectroscopy

Abstract

The electrical properties of Au nanoparticles protected by thiol-functionalized oligo(phenylene-ethynylene) (OPE), 1,4-bis-(3-mercapto-phenylethynyl)benzene have been investigated by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). The STM and scanning electron microscopy images of chemisorbed OPE-protected Au nanoparticles on Au(111) surface were similar, and the densities were almost identical. OPE-protected Au nanoparticles exhibited stochastic conductance switching behaviors, and current-voltage (I–V) and log I–V characteristics by STS at 100 K showed Coulomb blockade behaviors. The charging energy of Au nanoparticles was as high as 0.57 eV when the core diameter was 2.1 nm. Our results are significant for single-electron transistor memory applications.