Effect of Semi-Fluorinated Alkyl Side Chains on Conjugated Polymers with Planar Backbone in Organic Field-Effect Transistors.

Newly synthesized donor-acceptor (D-A) type of conjugated copolymer (PCTV-BTzF) with semi-fluorinated alkyl side chains, which has good solubility in common organic solvents, is described. Unlike polymers with hydrocarbon-based alkyl side chains, semi-fluorocabonated polymer leads to intriguing results. First, the self-organization behavior of the semi-fluoroalkyl side chains by the self-aggregate propensity between hydrocarbon and fluorocarbon induces patterned microstructural morphology in polymer films; second, it dominates the molecular orientation of polymers with planar back structure. Such unusual properties of the polymer with semi-fluoroalkyl side chains compared to that with the hydrocarbon ones are verified and characterized though various systematic characterizations, including temperature-dependent UV-Vis absorption spectroscopy, atomic force microscopy, and 2D-grazing incident X-ray diffraction measurement. As a result, PCTV-BTzF-based OFETs show the maximum p-type field-effect mobility of 1.02 cm2  V-1  s-1 in the 200 °C annealed films.