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Charge carrier mobility study of a mesogenic thienothiophene derivative in bulk and thin films

2014; Elsevier BV; Volume: 15; Issue: 4 Linguagem: Inglês

10.1016/j.orgel.2014.01.017

1878-5530

Leszek Mateusz Mazur, Andrea Castiglione, Kornel Ocytko, Farid Kameche, Romain Macabies, Abdelmalek Ainsebaa, David Kréher, Benoı̂t Heinrich, Bertrand Donnio, Sébastien Sanaur, Emmanuelle Lacaze, Jean‐Louis Fave, Katarzyna Matczyszyn, Marek Samoć, J. W. Wu, André‐Jean Attias, Jean‐Charles Ribierre, Fabrice Mathevet,

Conducting polymers and applications

A novel mesogenic 2,5-bis-(5-octylthiophene)-thieno[3,2b]thiophene (TT) derivative has been synthesized. The fused-ring thiophene, end-capped with two octylthiophenes, exhibits ordered lamellar mesophases which were characterized by polarizing optical microscopy, differential scanning calorimetry and small-angle X-ray diffraction at various temperatures. The charge transport properties were investigated by time-of-flight technique as a function of temperature. On cooling from isotropic phase, a maximum hole mobility value of 0.07 cm2 V−1 s−1 was measured in the highly ordered mesophase of the bulk films. Field-effect transistor experiments on both solution and vacuum deposited thin films have also been performed. The solution-processed films exhibit charge carrier mobilities several orders of magnitude lower than values extracted from bulk time-of-flight curves and from vacuum deposited thin film transistors. This work provides evidence that the melt-processing route is an efficient alternative to commonly used solution-processing for fabrication of charge transporting layers from liquid crystalline semiconductors, with performances comparable to evaporation techniques.