Anomalous time-independent diffusion of charge carriers in a random potential under a bias field

L. Pautmeier, Ranko Richert, H. Baessler

Research output: Contribution to journalArticle

113 Citations (Scopus)

Abstract

We present Monte Carlo simulation results for time-independent drift and spatial spreading of a packet of charge carriers executing a random walk within a manifold of hopping sites under a bias field. The shape of the density-of-states profile is assumed to be Gaussian (width σ). The ratio eD/μkT, equal to unity for ordinary diffusion, is found to increase dramatically with increasing disorder and bias field. For σ/kT=3.5 and fields of order 106 V cm-1, eD/μkT reaches values of order 103. The effect accounts for the anomalous spreading of time-of-flight profiles often seen in photocarrier transit time studies on various polymeric systems. The role of disorder in charge-carrier transport is emphasized.

Original languageEnglish (US)
Pages (from-to)587-601
Number of pages15
JournalPhilosophical Magazine B: Physics of Condensed Matter; Electronic, Optical and Magnetic Properties
Volume63
Issue number3
StatePublished - Mar 1991
Externally publishedYes

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Charge carriers
Time and motion study
Carrier transport
Monte Carlo simulation

ASJC Scopus subject areas

  • Engineering(all)

Cite this

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N2 - We present Monte Carlo simulation results for time-independent drift and spatial spreading of a packet of charge carriers executing a random walk within a manifold of hopping sites under a bias field. The shape of the density-of-states profile is assumed to be Gaussian (width σ). The ratio eD/μkT, equal to unity for ordinary diffusion, is found to increase dramatically with increasing disorder and bias field. For σ/kT=3.5 and fields of order 106 V cm-1, eD/μkT reaches values of order 103. The effect accounts for the anomalous spreading of time-of-flight profiles often seen in photocarrier transit time studies on various polymeric systems. The role of disorder in charge-carrier transport is emphasized.

AB - We present Monte Carlo simulation results for time-independent drift and spatial spreading of a packet of charge carriers executing a random walk within a manifold of hopping sites under a bias field. The shape of the density-of-states profile is assumed to be Gaussian (width σ). The ratio eD/μkT, equal to unity for ordinary diffusion, is found to increase dramatically with increasing disorder and bias field. For σ/kT=3.5 and fields of order 106 V cm-1, eD/μkT reaches values of order 103. The effect accounts for the anomalous spreading of time-of-flight profiles often seen in photocarrier transit time studies on various polymeric systems. The role of disorder in charge-carrier transport is emphasized.

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