Synthesis and characterization of semiconducting polymers composed of all electron-accepting monomer units for organic thin film transistors

In this paper, we report the synthesis of two conjugated polymers which were achieved by the Suzuki polycondensation reactions between dipotassium benzotriazolyl bis(trifluoroborate) and dibromofluorene or dibromo-naphthalimide comonomers and their characterization. These newly obtained polymers, P(BTZ-NI) and P(BTZ-FO), were found to have moderate molecular weights whose Mn values were 30 k and 42 k, respectively, and to be thermally stable with decomposition temperatures reaching as high as 410 °C. In terms of their electrical properties, P(BTZ-NI) was found to have an electron mobility of (4.4±0.8)×10-5 cm2 V-1 s-1, whereas P(BTZ-FO) showed a balanced ambipolar transport nature with hole and electron mobility of (5.6± 2.0)×10-5 cm2 V-1 s-1 and (5.0± 0.9)×10-5 cm2 V-1 s-1 respectively, as determined in top-gate, bottom contact organic thin film transistors (OTFTs). This result may be understood by considering the structures of the two conjugated polymers which are both composed of all electron-accepting monomer units.