Synthesis and characterization of three thienopyridazine-based copolymers and their application in OFET

Three low band gap thienopyridazine-based donor–acceptor conjugated polymers, PDTTPTT, PDTTPBT, and PDTTPBDT were synthesized by the Stille copolymerization of thienopyridazine with thienothiophene, benzodithiophene, and bithiophene, respectively. The optical band gaps of PDTTPTT, PDTTPBT, and PDTTPBDT polymers were determined as 1.41 eV, 1.43 eV, and 1.58 eV, respectively by UV absorption. The deep HOMO level of the three polymers was determined by cyclic voltammetry. The three polymers were fabricated to form organic field-effect transistors and their performance as p-type semiconductors were studied.