Unified Description of Charge-Carrier Mobilities in Disordered Semiconducting Polymers

Group Polymer Physics, Eindhoven Polymer Laboratories and Dutch Polymer Institute, Technische Universiteit Eindhoven, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Physical Review Letters (Impact Factor: 7.51). 06/2005; 94(20):206601. DOI: 10.1103/PhysRevLett.94.206601
Source: PubMed


From a numerical solution of the master equation for hopping transport in a disordered energy landscape with a Gaussian density of states, we determine the dependence of the charge-carrier mobility on temperature, carrier density, and electric field. Experimental current-voltage characteristics in devices based on semiconducting polymers are excellently reproduced with this unified description of the mobility. At room temperature it is mainly the dependence on carrier density that plays an important role, whereas at low temperatures and high fields the electric field dependence becomes important. Omission in the past of the carrier-density dependence has led to an underestimation of the hopping distance and the width of the density of states in these polymers.

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Available from: W.F. Frank Pasveer
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    • "However, it is very useful to have an analytical form of mobility μ dependence on temperature T, energetic scale of disorder σ, charge carrier concentration n and electric field strength F. An analytic description of mobility was suggested and applied to I-V characteristics calculations by Pasveer et al. (2005), but its equations are rather difficult, not physically clear and even incorrect in a broad range of parameters, because they results from fitting of numerical simulations. Although a different simple analytic model of mobility based on percolation theory by Shklovskii and Efros (1984) has been known for a very long time, it has never been applied to calculations of I-V characteristics of organic layers. "
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    • "solutions of the master equation coupled with the Poisson equation . The considered master equation model is exactly the same on which the state-of-the-art stationary modeling of transport in organic materials is based [17], [18], [27]. We describe a fully coupled numerical approach to this model which is applicable to the transient simulation. "
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