Why Can High Charge-Carrier Mobilities be Achieved Along π-Conjugated Polymer Chains with Alternating Donor-Acceptor Moieties?

Impressive charge-carrier mobilities have been measured over the past few years for a number of well-oriented π-conjugated polymer chains. Intriguingly, these polymers frequently have complex chemical structures consisting of repeat units with alternating electron-rich and electron-poor moieties. A priori, such structures do not lend themselves to the presence of strongly dispersive valence or conduction electronic bands, which are required to achieve small charge-carrier effective masses. Here, the factors that can lead to high carrier mobilities in the tens or even hundreds of square centimeter per volt per second are described briefly.