Electron transport in a gold nanoparticle assembly structure stabilized by a physisorbed porphyrin derivative

Abstract

Gold nanoparticles stabilized by meso-5,10,15,20-tetrakis͑2-thienyl͒porphyrin ͑2T͒ via physisorption ͑2T-AuNP͒ were synthesized, and the electronic transport of assemblies of these films was studied. The adsorption mechanism of 2T on gold nanoparticles was examined using UV-vis-NIR, IR, Raman, and 1 H-NMR spectroscopy, which showed no evidence of any covalent bonding between 2T and the gold nanoparticles. In temperature-dependent resistivity measurements, a crossover from thermally assisted hopping to EfrosShklovskii-type variable-range hopping ͑ES-VRH͒ was observed around 50 K on decreasing the temperature. At higher temperatures, the 2T-AuNP assembly structure followed an Arrhenius plot ͑E A =15 meV͒ with ohmic I-V characteristics at each measurement point. On the other hand, the activation energy at lower temperatures decreased nonlinearly in a T −1 plot, and the logarithm of the resistance obeyed a T −1/2 law, corresponding to an ES-VRH mechanism, which is predicted for disordered materials as a variable-range hopping mechanism influenced by strong Coulomb interactions. ES-VRH behavior has been observed previously in saturated molecule/gold nanoparticle assemblies and was confirmed in our 2T-AuNP assembly. Electronically active conjugated molecules were successfully incorporated between the nanoparticles, keeping the electronic structure of the gold nanoparticle and 2T moieties isolated from each other.

Coulomb blockade and hopping conduction in graphene quantum dots array

“…Although, this theory was developed for nanocrystal arrays of uniform sizes (monodisperse array), however, experimentally it was found to be true for polydispersed array as well [30,31]. From the fits, we obtain α = 3.1, 3.3 and 3.4 at 4.2 K, 10 K, and 15 K respectively.…”

Gold nanoparticle assemblies stabilized by bis(phthalocyaninato)lanthanide(III) complexes through van der Waals interactions

“…Fabrication of an electrical circuit through a solution-based process can also be achieved using weakly stabilized metal nanoparticles because the removability of the surface ligand permits a decrease in the sintering temperature, which is a crucial factor from the view-point of energy cost 12 , and field-effect transistor performance 13 . Physically stabilized nanoparticle assemblies are also favourable for achieving single-electron tunnelling 14 because physisorbed molecules prevent strong electronic coupling between nanoparticles and/or nanoparticle–molecule coupling that cause an increase in conductance and a decrease in the tunnelling decay constant 15 .…”

A Porphyrin‐Bridged Pd Dimer Complex Stabilizes Gold Nanoparticles

“…By considering the elemental analysis results,30 a single gold nanoparticle should interact with approximately 120 molecules of complex 4 ; the ratio between the number of gold atoms and the number of complex 4 molecules is equal to 16.7. In analogy to what was reported in the literature for meso ‐5,10,15,20‐tetrakis‐2‐thienylporphyrin physisorbed onto gold nanoparticles and by using the cross‐sectional area of a similar compound that can be adsorbed onto gold nanoparticles in flat or edge‐on configurations (approximately 1.7 and 0.8 nm 2 ),15 we can assume that 120 molecules of complex 4 are arranged on the gold surface with a tilted conformation (see Figure 3b) and in which porphyrin rings interact with each other, as reported for similar porphyrin complexes adsorbed onto flat gold surfaces 21,31…”

“…The transduction of optical radiation to current in a molecular circuit made by a network array of AuNPs bridged through a dithiol–Zn porphyrin trimer has been recently reported, which suggests that the plasmon‐controlled electrical properties of these molecules can be tailored to be applied in optoelectronic and energy‐harvesting devices 14. Gold nanoparticles are usually stabilized by a sulfur–Au covalent bond, and a few examples of physisorption of a porphyrin derivative without covalent bonding are known 15. The assembly of gold nanoparticles stabilized by noncovalently bonded electro‐optically active conjugated molecules is a suitable model to study the electronic structure of the molecules that interact with gold nanoparticles.…”