研究目的
To understand the origin of the negative temperature coefficient of mobility in PEDOT:TOS and reconcile it with the hopping character of transport.
研究成果
A negative mobility temperature coefficient in PEDOT:TOS at high temperatures can be explained within a hopping transport model, without invoking any assumption about the transition to metallic band-like transport, provided that the evolution of the density of states and the transfer integrals distribution induced by morphological changes when the temperature is increased are taken into account. An extension of the GDM has been proposed to model these phenomena, and it has been shown that it can successfully account for experimental results.
研究不足
The computational limitations on the size of the MD system investigated lead to strong fluctuations of the mobility curves. The model does not account for the possible importance of the Quantum Nuclear Tunneling effect.
1:Experimental Design and Method Selection:
Multi-scale mobility calculations in PEDOT:TOS for the model of hopping transport, where changes in the morphology and the density of states (DOS) with the temperature were explicitly taken into account. The morphology was calculated using Molecular Dynamics simulations, and the hopping rates between the chains were calculated quantum-mechanically following the Miller-Abrahams formalism.
2:Sample Selection and Data Sources:
PEDOT chains doped with Tosylate (TOS) were used as samples. The morphology was obtained from MD simulations.
3:List of Experimental Equipment and Materials:
Molecular Dynamics simulations software, quantum-mechanical calculation tools for transfer integrals and localized states energies.
4:Experimental Procedures and Operational Workflow:
MD simulations of the material where the temperature is progressively changed were performed, then QM calculations of the transfer integrals (TI) and localized states energies were performed for several snapshots of the morphology obtained from the MD simulations, and finally the carrier mobility was calculated using the same snapshots.
5:Data Analysis Methods:
The carrier mobility was obtained by solving the Master Equation for transport in the mean field fashion.
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