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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    ABSTRACT: An analytic model of mobility dependence on charge-carrier concentration based on percolation theory was modified by the use of the transport level concept, including field dependence of transport level. This model was applied to calculations of I-V characteristics of a single organic layer under space-charge limited regime.
    Physics Procedia 12/2015; 72:438-443. DOI:10.1016/j.phpro.2015.09.089
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    • ", [62]. On the other hand, it has been shown that a Gaussian DOS is suitable for describing intrinsic energetic distribution of states in a disordered organic semiconductor [63], [64]. The characteristic carrier-density-dependence of hopping mobility in Gaussian DOS is expected to be directly linked to V GS -dependent mobility in OFETs. "
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    ABSTRACT: In spite of impressive improvements achieved for organic field-effect transistors (OFETs), there is still a lack of theoretical understanding of their behaviors. Furthermore, it is challenging to develop a universal model that would cover a huge variety of materials and device structures available for state-of-the-art OFETs. Nonetheless, currently there is a strong need for specific OFET compact models when device-to-system integration is an important issue. We briefly describe the most fundamental characters of organic semiconductors and OFETs, which set the bottom line dictating the requirement of an original model different from that of conventional inorganic devices. Along with an introduction to the principles of compact modeling for circuit simulation, a comparative analysis of the reported models is presented with an emphasis on their primary assumptions and applicability aspects. Critical points for advancing OFET compact models are discussed in consideration of the recent understanding of device physics.
    IEEE Transactions on Electron Devices 02/2014; 61(2):278-287. DOI:10.1109/TED.2013.2281054 · 2.47 Impact Factor
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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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    ABSTRACT: Application of the master equation approach to the space-charge-limited transient situation is considered. The transient responses of thin organic films are simulated by solving the master equation of transport coupled with the Poisson equation. Hopping of the charge carriers between sites is described by the Miller-Abrahams formula. Sites with the Gaussian energetic distribution are localized on a Cartesian lattice. The solutions are calculated using the fully coupled Newton-Raphson method. The details of implementation permitting efficient stationary and transient simulation of unipolar transport are given. This approach gives much better agreement to the experimentally observed space-charge-limited current transient responses than the widely used drift-diffusion model. It is shown that the time position of the transient peak is affected by the contact barrier height. In the case of thin strongly disordered samples, the best observability of the peak is predicted for the intermediate values of the contact barrier.
    IEEE Journal of Selected Topics in Quantum Electronics 09/2013; 19(5):1-7. DOI:10.1109/JSTQE.2013.2246775 · 2.83 Impact Factor
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