Morphology Associated Positive Correlation between Carrier Mobility and Carrier Density in Highly Doped Donor-Acceptor Conjugated Polymers

The effect of FeCl₃ doping on charge transport is compared in ordered DPPDTT and more disordered IDTBT films. DPPDTT shows a strong mobility increase under heavy doping, whereas IDTBT changes little. The different responses link the initial molecular arrangement to the balance between coherent and incoherent transport, showing why increasing carrier density alone does not determine conductivity.