We report on the charge transport and absorption properties of a low bandgap quinoidal oligothiophene derivative [QQT(CN)4]. Organic field-effect transistors based on QQT(CN)4 thin films show an ambipolar p-type dominant behavior and can be converted to n-type by thermal annealing at 100 degrees C for 30 minutes. Absorption spectra and atomic force microscopy measurements carried out in both neat films and polymer blends provide new important insights into the role of the degree of aggregation and the intermolecular interactions on the semiconducting and photophysical properties of this organic electronic material.