reduction of steric hindrance between the solubilising alkyl groups and adjacent thiophene rings. The improved crystalline structure of PSBTBT resulted in a higher charge carrier mobility and improved solar cell performance in blends with fullerene derivatives. Low band gap co-polymers containing silafluorene, 40 dithieno[3,2-b:2′,3′-d]silole 7 and silaindacenodithiophene have recently demonstr...
