Numerical Studies of Hopping Transport in Disordered Molecular Solids
Photoexcited charge conduction in molecularly-doped polymers can be described in terms of a biased random walk among a set of energetically and spatially disordered molecular centers. We describe a numerical renormalization procedure for studying hopping transport in disordered systems of this type. In this procedure, transport properties of cubic regions drawn randomly from the sample are calculated exactly using equation of motion methods. The original system is then replaced with a new one, defined on a larger length scale, but possessing the same macroscopic transport properties as the original. Fluctuations of the system are smaller at the new length scale, allowing for an accurate calculation of the conductivity using effective medium theory. The approach has been used to study the crossover between nearest-neighbor and variable-range hopping, where it has revealed that the exponential dependence of mobility of the mean interparticle spacing is substantially influenced by the magnitude of the energetic disorder in the system.
P. E. Parris, "Numerical Studies of Hopping Transport in Disordered Molecular Solids," Proceedings of SPIE - The International Society for Optical Engineering, vol. 2526, pp. 13-22, SPIE--The International Society for Optical Engineering, Aug 1995.
The definitive version is available at http://dx.doi.org/10.1117/12.217315
Keywords and Phrases
Biased random walk; Disordered molecular solids; Hopping transport; Molecular doping; Charge transfer; Doping (additives); Mathematical models; Numerical methods; Order disorder transitions; Polymers; Transport properties; Optical materials
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