Random walk numerical simulation for hopping transport at finite carrier concentrations: diffusion coefficient and transport energy concept

Gonzalez-Vazquez, J. P., Anta, Juan A. and Bisquert, Juan (2009) Random walk numerical simulation for hopping transport at finite carrier concentrations: diffusion coefficient and transport energy concept. Physical Chemistry Chemical Physics, 11 44: 10359-10367. doi:10.1039/b912935a


Author Gonzalez-Vazquez, J. P.
Anta, Juan A.
Bisquert, Juan
Title Random walk numerical simulation for hopping transport at finite carrier concentrations: diffusion coefficient and transport energy concept
Journal name Physical Chemistry Chemical Physics   Check publisher's open access policy
ISSN 1463-9076
1463-9084
Publication date 2009-01
Sub-type Article (original research)
DOI 10.1039/b912935a
Volume 11
Issue 44
Start page 10359
End page 10367
Total pages 9
Place of publication Cambridge, United Kingdom
Publisher R S C Publications
Language eng
Formatted abstract
The random walk numerical simulation (RWNS) method is used to compute diffusion coefficients for hopping transport in a fully disordered medium at finite carrier concentrations. We use Miller–Abrahams jumping rates and an exponential distribution of energies to compute the hopping times in the random walk simulation. The computed diffusion coefficient shows an exponential dependence with respect to Fermi-level and Arrhenius behavior with respect to temperature. This result indicates that there is a well-defined transport level implicit to the system dynamics. To establish the origin of this transport level we construct histograms to monitor the energies of the most visited sites. In addition, we construct “corrected” histograms where backward moves are removed. Since these moves do not contribute to transport, these histograms provide a better estimation of the effective transport level energy. The analysis of this concept in connection with the Fermi-level dependence of the diffusion coefficient and the regime of interest for the functioning of dye-sensitised solar cells is thoroughly discussed.
Keyword Sensitized solar-cells
Disordered organic materials
Of-states distribution
Electron transport
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Mathematics and Physics
 
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