Five new donor-acceptor (X-DAD'AD)(n) type conjugated polymers have been synthesized using different X blocks based on carbazole, fluorene, silafluorene, benzodithiophene, and cyclopentadithiophene (CPDT). The strongly electron donating CPDT unit was used as a central D' fragment to enhance intramolecular charge transfer interactions along the polymer backbone and reduce the bandgap of the resulting conjugated polymers. Apparently, the nature of the X block impacts the photophysical, morphological and optoelectronic properties of the designed polymers as well as their performance in bulk heterojunction solar cells. Fluorene-based copolymer P2 in combination with [70]PCBM delivered the best power conversion efficiency of 5.0% with a V-oc of 0.78 V, a J(sc) of 11.1 mA/cm(2) and a FF of 57%. Possibility for easy variation of the X and D' blocks in the designed materials paves a way towards design of a variety of new materials for optoelectronic applications.