Tunable Electrical Transport through Annealed Monolayers of Monodisperse Cobalt−Platinum Nanoparticles

Abstract

We synthesized monodisperse cobalt-platinum nanoparticles Co(0.14-0.22)Pt(0.86-0.78) of 9 nm in diameter by colloidal chemistry methods and deposited them by the Langmuir-Blodgett technique as highly ordered monolayers onto substrates with e-beam defined gold electrodes. Upon annealing we observe an increase of conductivity over more than 4 orders of magnitude. A first attempt of explanation of this unanticipated effect, a nanoparticle displacement, could not be confirmed for annealing temperatures below 400 °C. A second approach, a carbonization of the ligands, however, could be confirmed by Raman spectroscopy. The simple thermal treatment allows tuning essential properties of electronic devices based on nanoparticles by the manipulation of the interparticle coupling, namely the electrical conductivity, the Coulomb blockade characteristic, and the activation energy of the system.

Controllability of the Coulomb charging energy in close-packed nanoparticle arrays

“…Although many research efforts have been devoted to investigate the Coulomb charging energy in nanoparticle assemblies [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30], discrepancies still exist about some fundamental questions. One example is about the estimation of the Coulomb charging energy in nanoparticle assemblies.…”

Probing the localization of charge and the extent of disorder through electronic transport on Au nanoparticle–copper phthalocyanine multijunction networks

“…The electric response of the network depends strongly upon the electrode distance. This occurs because certain physical properties like the overall contact resistance, the percolation threshold, the static energetic disorder of hopping sites , and the coupling to the environment change dramatically with array size. For the 50‐nm (Fig.…”

Substantial Difference in Ordering of 10, 15, and 20 nm Iron Oxide Nanoparticles on a Water Surface: In Situ Characterization by the Grazing Incidence X-ray Scattering

“…Alternatively, it has been shown that the most ordered and large area arrays of MNPs 3 can be assembled on water surface [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] . The process involves deposition of evaporative solution of MNPs on a water surface where it spreads out to form a colloidal solution film.…”

“…Providing sufficient resolution for study nano-objects they, in addition, probe large area sample surfaces due to a large beam spread resulting from a very shallow angle of incidence. Assemblies of MNPs on solid substrates were intensively studied by means of grazing incidence X-ray reflectivity (XRR) and small-angle X-ray scattering (GISAXS) 12,13,16,17,27,31,35,37,38 , neutron reflectivity (NR) and grazing incidence small-angle neutron scattering (GISANS) 17 In the present study, for the first time, to our knowledge, a unique combination of in-situ GISAXS and XRR techniques, accompanied by the pressure-area isotherm analysis, BAM and ex-situ SEM were applied for investigation of super-lattices of magnetic nano-particles as they form directly on water surface in a Langmuir trough. Size and value of the magnetic 5 …”