Percolation model of electron and hole mobility in liquid mixtures

Abstract

The theory of charge percolation, originally developed for inhomogeneous mixtures of metals, is transformed to describe mobility of electrons and holes in homogeneous liquid mixtures. Systems in which the energies of the charge carriers are independent of composition are expected to obey the predictions of this formalism. Here concentration fluctuations act as microscopic inhomogeneities. As examples, hole mobility in trans -decaline-cyclohexane, and electron mobility in hexafluorobenzene-benzene and in n-hexane-ethanol mixtures are treated. The number of molecules interacting with a charge carrier appears as an important parameter. Mobility versus concentration curves are calculated in the entire concentration range and are in good agreement with observations. Finally a method is proposed for estimating electron mobility in hexafluorobenzene.

Electron transport in o- and m-xylene under high pressure

“…24,25 Although the parameter values obtained might be in error as the mobility does not become completely pressure independent at the highest pressures at all temperatures, the values of the mobility at the highest pressures were used to make plots of log(T) vs 1/T ͑Fig. 6͒ in order to make a qualitative comparison with the benzene and toluene results.…”

Multimer Radical Ions and Electron/Hole Localization in Polyatomic Molecular Liquids: A Critical Review

“…The electron in the solvent anion is strongly bound: the anion does not react with such efficient electron acceptors as SF 6 , although it reacts with CBr 4 , CCl 4 , and (NC) 2 C=C(CN) 2 (with rate constant as large as 1.5x10 11 M -1 s -1 ). Addition of small amounts of inert solvents (benzene, saturated hydrocarbons, C 6 F 12 ) results in the exponential decrease in the anion mobility with the molar fraction x of the inert solvent [41,42]. E.g., addition of 5 mol % of cyclohexane drops the mobility by 50% relative to neat C 6 F 6 [41].…”

“…This decrease can be approximated by (1-x) n , where the exponent n=15-20. A "percolation" model of charge migration [42] suggests that the negative charge in C 6 F 6 is spread over ca. 12 solvent molecules; this is why even slight dilution has strong effect.…”

Mass spectra and photoelectron spectroscopy of negatively charged benzene clusters, (benzene)n− (n=53–124)

“…The downward-pointing arrow indicates the peak maximum of PE spectrum, i.e., VDE. hexafluorobenzene (C 6 F 6 ) has been reported to be quite low ͑about one-order of magnitude smaller when compared with liquid benzene͒, which is attributed to an electron hopping model: A Ϫ ϩA→AϩA Ϫ , as the electron transport mechanism, 22 unlike the case of liquid benzene. This contrast in the behavior of electron in bulk benzene and C 6 F 6 should be seen also in the corresponding small molecular aggregates, i.e., clusters.…”