The Effect of Nanoscale Confinement on the Collective Electron Transport Behavior in Au Nanoparticles Self-Assembled in a Nanostructured Polystyrene-block-poly(4-vinylpyridine) Diblock Copolymer Ultra-thin Film†

This study involves the collective electron transport behavior of sequestered Au nanoparticles in a nanostructured polystyreneblock-poly(4-vinylpyridine). The monolayer thin films (ca. 30 nm) consisting of Au nanoparticles self-assembled in the 30-nm spherical poly(4-vinylpyridine) domains of an polystyrene-block-poly(4-vinylpyridine) diblock copolymer were prepared. From the current-voltage characteristics of these thin films, the collective electron transport behavior of Au nanoparticles sequestered in the spherical poly(4-vinylpyridine) nanodomains was found to be dictated by Coulomb blockade and was quasi one-dimensional, as opposed to the three-dimensional behavior displayed by Au nanoparticles that had been dispersed randomly in homo-poly(4-vinylpyridine). The threshold voltage of these composite increased linearly upon increasing the inter-nanoparticle distance. The electron tunneling rate constant in the case of Au nanoparticles confined in poly(4-vinylpyridine) nanodomains is eight times larger than that in the randomly distributed case and it increases upon increasing the amount of Au nanoparticles. This phenomenon indicates that manipulating the spatial arrangement of metal nanoparticles by diblock copolymer can potentially create electronic devices with higher performance.