We have synthesized liquid crystalline terthiophene (TTP) derivatives having hydroxyl groups in ω-position of side chains, i.e., 5-hexyl-5’’-(6-hydroxyhexyl) terthiophene (6-TTP-6ol) and 5, 5’’-bis (6-hydroxyhexyl) terthiophene (6-TTP-6diol), and characterized their liquid crystallinity by differential scanning calorimeter (DSC), polarized optical microscopic observation (POM) and X-ray diffraction (XRD) measurement. And charge carrier transport properties by time-of-flight (TOF) measurement. These hole mobilities determined by TOF had not been changed much despite relatively the large dipole of hydroxyl group of 1.8-2.2D, compared with a non-hydroxyl derivative and their values are 10−3-10−2cm2V−1s−1. This fact indicates that the charge carrier mobility is not affected by polar groups, if it is substituted at the far −end position from the TTP core responsible for carrier transport, indicating a possible molecular design of a functionalized liquid crystalline organic semiconductor with polar groups without decreasing the mobility.
Toyohiro Fukuda, Jun-ichi Hanna, "Effect of ω-hydroxyl Group of Side Chains on Phase Transition Behavior and Charge Transport Properties in Terthiophene Liquid Crystals" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP27), 2011, pp 561 - 563, https://doi.org/10.2352/ISSN.2169-4451.2011.27.1.art00039_2