New amorphous semiconducting copolymers, poly(9,9-dialkylfluorene)-alt-(3-dodecylthienyl-divinylbenzene-3-dodecyl thienyl) derivatives (PEFTVB and POFTVB), were designed, synthesized, and characterized The structure of copolymers was confirmed by H NMR, IR, and elemental analysis The copolymers showed very good solubility in organic solvents and high thermal stability with high T-g of 178-185 degrees C The weight average molecular weight was found to be 107,900 with polydispersity of 3 14 for PEFTVB and 76,700 with that of 3 31 for POFTVB UV-vis absorption studies showed the maximum absorption at 428 nm (in solution) and 435 nm (in film) for PEFTVB and at 430 nm (in solution) and 436 nm (in film) for POFTVB Photoluminescence studies showed the emission at 498 nm (in solution) and 557 nm (in film) for PEFTVB and at 498 nm (in solution) and 536 nm (in film) for POFTVB The solution-processed thin-film transistors showed the carrier mobility of 2 x 10(-4) cm(2) V-1 s(-1) for PEFTVB-based devices and 2 x 10(-5) cm(2) V-1 s(-1) for POFTVB-based devices (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A Polym Chem 48 3942-3949, 2010