We present here the synthesis, characterization, and field-effect performance of a novel n-channel semiconducting molecule TIFDMT and of the corresponding thiophene-based copolymer P-IFDMT4 based on the indenofluorenebis (dicyanovinylene) core. TIFDMT-based field-effect transistors fabricated by spin-coating exhibit high electron mobilities of 0.10-0.16 cm(2)/V S in air, low turn-on voltages (-0 to +5 V), and high on/off ratios of 10(7)-10(8). These devices also exhibit excellent air stability over a prolonged time of storage in ambient conditions. P-IFDMT4-based devices exhibit the first example of an air-stable ambipolar polymer processable from solution.