A novel " double cable " polymer was developed. Which are generally composed of a carbazole-bithiophene backbone functionalised with perylene tetracarboxylicdiimide (PDI) units as electron acceptors, to avoid phase separation problems between donors and acceptors. The study on the physical properties of the polymer and the interaction of the perylene diimide electron accepting substituents with the polymer backbones in this class of " double cable " polymers is presented.