Papers by Keyword: Hopping

Abstract: Replacing traditional liquid electrolytes by polymers will significantly improve electrical energy storage technologies. However, the ion transport mechanism in polymers has been one of the main barriers to further improvement in Li-ion batteries and is still not completely clarified. In an effort to gain a better understanding of the conduction phenomena in electrolytes, a comprehensive survey of all transport mechanism including solvation, segmental motion and hopping, is presented here. Included are a survey of the fundamentals of diffusion and conductivity in polymer electrolytes; recent developments in Li salts; and a detailed discussion about ion transport mechanism with representative references.

Abstract: The structural and electrical transport properties of La0.67Ba0.33Mn1-yTiyO3 manganite, with y = 0.00, 0.05, 0.10, 0.15, 0.20, 0.40 and 0.60, prepared using the solid state reaction technique have been investigated. The X-ray diffraction spectra of the Ti substituted samples showed the formation of single phase compound with Pm3m cubic structure except for the y = 0.60 sample, which showed La2Ti2O7 phase formation. Lattice parameter increased with Ti content and then decreased at y = 0.60. Resistivity versus temperature study showed that only samples with y = 0.05 and 0.10 exhibited both metallic and semiconductor-like behaviour with the metal-insulator transition temperature, Tp of 167 K and 43 K, respectively. At higher Ti concentration the samples only showed the semiconducting behaviour. At T < Tp the resistivity curves followed the ρ = ρo1 + ρ1T2 relation and for T > Tp, the curves can be fitted with the nearest neighbour hopping (NNH), variable range hopping (VRH) or/and the small polaron hopping (SPH) models.

Abstract: This paper adopted molecular dynamics technique to simulate the nano-scale transport phenomena inside air electrode of the URSOFC. A molecular model consist of 135 atoms has been built as the simulation target. Born-Meyer-Buckingham potential function is used and a perovskite type structure is built. Simulation results demonstrate hopping mechanism of oxygen ions inside air electrode by calculating mean square displacement of oxygen ions. Also, the effect of the operating temperature for the ionic conductivity is able to be predicted by the present study.

Abstract: General characteristics of dye-sensitized nanoporous semiconductor electrode systems are summarized, with a particular emphasis on dye-sensitized solar cells. Properties of these electrode systems which distinguish them from conventional bulk semiconductor electrodes are highlighted. Current understanding of electron transport in dye-sensitized solar cells, in terms of the diffusion and multiple trapping models, is reviewed. Alternative transport and recombination theories are also briefly reviewed. Electron transfer at the semiconductor/electrolyte interface in dye-sensitized solar cells is reviewed and recent experimental results obtained by the authors are highlighted. As applicable, common techniques for characterization of electron transport and transfer in dye-sensitized solar cells are described, with reference to case studies where the electron diffusion length in dye-sensitized solar cells has been estimated. The steady-state aspects of the dye-regeneration process are also reviewed, together with the cross-surface percolation of holes in the dye monolayer and the finite-length diffusion of redox species in the electrolyte.

Abstract: Hall measurement is an effective means to measure carrier density and mobility in metals and semiconductors. This work examined the carrier mobility determined in the accumulation layer of organic field-effect transistors (OFETS) and proposed a method to explain data taken from rubrene single-crystal devices. The model was used to extract information on the trap states and the properties of the transport layer at different temperature.