Investigation on charge transport properties of Cyclopentadithiophene-based D-A type semiconducting copolymers

We have studied the charge transporting properties in Cyclopentadithiophene (CDT)-based donor (D) – acceptor (A) type semiconducting copolymer, which is known to have high performance, as an active layer of a field-effect transistor. In order to investigate the relationship between the charge-carrier mobility and the structural property of each polymer, the CDT-based polymer thin-films were analyzed by ultraviolet-visible spectroscopy, Raman spectroscopy, and density function theory (DFT) simulation. From our experimental results, it was found that the charge transports in the CDT-based polymeric thin-film is more dependent on the efficient intramolecular transport than the intermolecular charge transports. These results suggest that improving the planarity and rigidity of the polymer backbone is essential for efficient intramolecular charge transfer in order to design a high performance D-A type semiconducting copolymer.