Reduced Polaron-Dopant Interaction

As we discussed above, the doping of polythiophene/IP composite is somehow inevitable, because (i) the ionization potential is only around 5 eV (ii) the material can only be prepared from solution, and during solvent evaporation the residual impurity in solvent is concentrated and (iii) the intrinsic defect in polymer chain or undefined end groups might act as dopant Certainly, the unintentional doping can be controlled in a low level. Therefore, let us consider the enhanced mobili-ty/conductivity from the role of carrier-dopant interactions. 

Here we introduce a Monte Carlo model to consider the influence of carrier-dopant interaction on the charge transport [28]. 

Microscopically, the carrier hops from one localized state to the neighbor one, and the energy E of localized site can be written as 

Gaussian distribution function is usually used to represent the density of states (DOS), which is given by 

The Coulomb potential coui of a hole carrier as a result of interaction with dopant anions in the material is 

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