Variable single electron charging energies and percolation effects in molecularly linked nanoparticle films

Abstract

We study electrical transport in strongly coupled, molecularly linked, gold nanoparticle (NP) films whose bulk dc conductances are governed by percolation phenomena. Films with fewer NPs exhibit current suppression below a threshold voltage, likely due to single-electron charging of NP clusters. In some cases, the thresholds are very large (∼1 V) and suppression persists to room temperature. The thresholds tend to decrease with increasing amounts of NPs in the film, and eventually, metal-like conductance is observed down to at least 10 K. The observed trend toward metal-like conductance, despite the presence of film disorder, is enabled by strong inter-NP coupling and increasing film connectivity. The latter is an inherent property of molecularly linked NP films due to both robust chemical inter-NP linkages provided by alkane dithiol linker molecules, coupled with the ability to grow chains of connected NPs to arbitrary lengths through cyclical Au/dithol treatments. In the case of small thresholds, our data is well described by a high-temperature approximation of “orthodox” theory for a linear array of tunnel junctions.

Self‐Assembly of Nanoparticles on Live Bacterium: An Avenue to Fabricate Electronic Devices

“…[1] On the nanoscale, the energy cost to insert a single electron in a nanoparticle is over 1-10 times greater than the thermal energy, and the flow of the interparticle current takes place through the transport of single electrons, as explicitly shown by transport studies on single nanoparticles, [11,12] their 2D and 3D assemblies, [13][14][15][16] and single-nanoparticle devices (such as single-electron transistors [17,18]). The above studies demonstrate that a percolating cluster of metal nanoparticles is a viable unit to fabricate single-electron devices, whereby micronscale clusters allow an easy-to-fabricate, robust interconnection network for the nanodevice system.…”

“…Because metal nanoparticles such as gold are stabilized in solution by electrostatic repulsion, the formation of a percolating cluster on physical substrates requires either an organic cross-linker to bind the particles [13,19] or a polyelectrolyte to shield the charge of the particles. [16,20] For biological substrates, the highly selective deposition of nanoparticles relies on either highly specific binding (such as DNA hybridization [21][22][23] or biotin-streptavidin interactions [24]) or strong specific intermolecular interaction (such as electrostatic interactions [25][26][27]). …”

Electrochemical properties of ferrocenylalkane dithiol-gold nanoparticle films prepared by layer-by-layer self-assembly

“…7c. Fluctuations in DE p are likely due to the disordered architecture of the film driven by the nature of the self-assembly process [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. Observed increases in peak width with increasing number of layers ( Fig.…”

“…Gradually, as sufficient amount of material is added, sample-spanning clusters form. A percolation threshold is crossed and charge transport becomes dominated by scattering processes [23][24][25]. Elastic scattering is expected to be particularly strong in this limit, as charges inevitably encounter NP surfaces as they transfer from particle to particle.…”

“…An ability of NPs to self-assemble onto an FDT-functionalised surface was confirmed via UV-vis absorption spectroscopy. Glass slides were functionalised with 3-aminopropyldiethoxymethyl silane (APDEMS), as previously described [23][24][25]. The functionalised slides were then alternately immersed in NP solution (2 h) and 1 mM ethanolic FDT solutions (10 min), with intervening rinsing and drying steps.…”