| Abstract
| - Mobilities of charge carriers in cast and spun films of poly(3-hexylthiophene)s (PHTs) with regioregularitiesof 97%, 81%, 70%, and 54% (denoted as PHT97%, PHT81%, PHT70%, and PHT54%, respectively) areevaluated as a function of doping level. A common feature of mobility vs doping level plots for all the PHTfilms is that the mobility decreases initially with the increase of the doping level and then starts to risedrastically at ca. 1% doping level. No large mobility difference is observed between cast and spun films ofeach PHT. In contrast, the difference in regioregularity of PHT resulted in a large mobility difference, especiallyin the low doping regime. At the highest doping levels of ca. 20%, the apparent mobility values reach 0.4 and0.01 cm2 V-1 s-1 for the cast films of PHT97% and PHT54%, respectively. These features of the mobilityplots are discussed in connection with self-assembled structures of PHT films studied by electrochemical,in-situ ESR, in-situ UV−vis−NIR, and X-ray diffraction measurements. It is concluded first that mobilitiesof polarons are mainly controlled by the rate of an interchain charge hopping and second that the evolutionof metallic conduction featured by the sharp mobility increase is irrelevant to the interchain stacking, orrather governed by an intrachain route.
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