Synthesis and characterization of graft polystyrenes with para-substituted π-conjugated oligo(carbazole) and oligo(carbazole-thiophene) moieties for organic field-effect transistors

In this research, two styrene-derivative monomers based on bicarbazole and carbazole-bithiophene-carbazole (StCz2 and StCzT2Cz) were prepared and further free-radical polymerized (PStCz2 and PStCzT2Cz) to form graft π-conjugated polymers. The thermal, optical, and electrochemical properties of these studied monomers and polymers were fully characterized for studying the relationships of the structures to the properties. The field-effect characteristics of the polymers were also studied, a highest hole mobility on the order of 1.1 × 10−3 cm2V−1s−1 was obtained with PStCzT2Cz. The morphology of the polymeric active layers was also investigated with X-ray diffraction and atomic force microscopy to realize the relationships of the structures to the electric characteristics.