Solution-processable polymers based on strong acceptor benzobis(thiadiazole) (BBT) units were synthesized to form unipolar n-type organic thin-film transistors (OTFTs) that were electronically characterized. These polymers exhibited a narrow band-gap and low LUMO level, resulting in distinct n-type semiconducting properties within the OTFT devices. The BBT-thiazole polymer material showed better electron transport than BBT-thiophene polymers. The use of electron-deficient units was found to be suitable for the realization of the unipolar n-type semiconducting polymers.