Polymer based on benzothiadiazole-bridged bis-isoindigo for organic field-effect transistor applications

Two isoindigos were symmetrically connected by 2,1,3-benzothiadiazole core to form an acceptor2 -acceptor1-acceptor2 monomer. The new monomer was used as electron acceptor unit in construction of a unique donor/acceptor polymer with donor-acceptor2-acceptor1-acceptor2 repeating units. The optical and electrochemical properties of the monomer and polymer were investigated. The optical band gap of monomer and polymer were about 1.86 and 1.65 eV, respectively. Both monomer and polymer showed relatively low-lying highest occupied molecular orbital energy levels and the corresponding values were -5.90 and -5.56 eV for monomer and polymer, respectively. The semiconducting properties of new materials were also studied. Organic field effect transistors based on solution processed thin films of the polymer displayed typical p-channel characteristics with a hole mobility of 0.02 cm(2) (V s)(-1) in ambient conditions. (c) 2015 Elsevier Ltd. All rights reserved.