(3Z,3′Z)-3,3′-(Hydrazine-1,2-diylidene)bis(indolin-2-one) as a new electron-acceptor building block for donor-acceptor π-conjugated polymers for organic thin film transistors

(3Z,3'Z)-3,3'-(Hydrazine-1,2-diylidene)bis(indolin-2-one) (HBI) containing an azine linkage is used as a novel amide-based pi-conjugated electron-accepting building block for constructing donor-acceptor (D-A) pi-polymer semiconductors. Copolymers of HBI and bithiophene are synthesized, which show small optical band gaps (similar to 1.6 eV) and quite low-lying highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels (E-HOMO = -5.6 eV; E-LUMO = -4.0 eV). The spin-coated polymer thin films are highly crystalline with a favoured edge-on lamellar chain packing motif, and exhibit high ambipolar charge transport performance with hole and electron mobilities up to 0.11 and 0.035 cm(2) V-1 s(-1), respectively.