A new solution-processable acceptor-acceptor conjugated copolymer (P1) based on perylene diimide (PDI) incorporating planar electron-deficient fluorenone was synthesized by palladium(0)-catalyzed Suzuki coupling reaction. Relative to the donor-acceptor conjugated copolymer (P2) of PDI and dithienothiophene, polymer P1 exhibits 0.1 eV down shift of lowest unoccupied molecular orbital (LUMO) level, 70 nm blue shift of low-energy absorption band, and 0.36 eV increase of optical band gap. Polymer P1 in top-contact bottom-gate organic field-effect transistors exhibits a saturation electron mobility of 0.01 cm2/(V s) in air, while P2 does not function in the same device in air. The better air stability of P1 is attributed to a more dense packing of the polymer chains excluding oxygen or water and lower LUMO level of P1. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012