Two π-conjugation expanded isoindigo derivatives (DIID-PhCO and TIID-PhCO) composed of up to 18 rings and two donor-acceptor conjugated polymers based on DIID-PhCO were synthesized. Both polymers are ambipolar semiconductors with balanced hole and electron mobilities up to 0.10 and 0.14 cm2 V-1 s-1, respectively, under ambient conditions.