A series of low band-gap conjugated polymers with intramolecular charge transfer properties were synthesized and bulk heterojunction devices based on these polymers were fabricated. The electrochemical and photophysical properties of the polymers were tuned by using different electron withdrawing molecules or ruthenium complexes as the comonomer. Preliminary results suggested that the electronic structures of the polymer were significantly altered by the incorporation of different acceptor units. The polymers also demonstrated intense absorption bands in the visible region, indicating that they are suitable photoactive materials in bulk heterojunction devices. The synthesis and characterization of a series of organic donor-acceptor copolymers were studied. All of the polymers contained alternating cyclopenta[2,1- b:3,4-b’]dithiophene (CPDT) units. The effects of the different acceptor monomers were evaluated. The electron-withdrawing carboxylate and amide functional groups of the acceptors were found to effectively stabilize the HOMO levels of the polymer, and the optical band-gaps were significantly reduced. Bulk heterojunction devices were fabricated using the polymers and 6,6-phenyl C61 butyric acid methyl ester (PCBM) as donors and acceptors respectively. These devices exhibited high open circuit voltage (Voc) up to 0.86 V. The extended photosensitizing range was confirmed by the external quantum efficiency (EQE) spectra. The device performance was further improved by optimizing the active layer thickness and applying 1,8-diiodooctane in the blend solution. A new synthetic route to novel ruthenium containing polymers was also reported. [Ru(L)(L’)Cl2] complexes (L and L’ = bidentate N^N ligands) with a dibromo-substituted ligand were found to be polymerizable by Stille cross-coupling reaction. The subsequent displacement of the chloride ligands by thiocyanate was highly effective and the structures of the target polymers were fully characterized. The main chain absorption showed a significant red-shift upon metal coordination and the metal-to-ligand charge transfer (MLCT) of the complex strengthens the photon harvesting ability of the polymer. The dual function of these Ru(II) complexes demonstrated a new avenue to develop new classes of optoelectronic materials. The extent of _-delocalization of the ancillary ligands also showed interesting effects on the electronic properties of the polymers. Bulk heterojunction devices were fabricated. Photovoltaic response was observed in these devices, and the device performance can be improved by further modifying the surface morphology of the blend films. / published_or_final_version / Chemistry / Master / Master of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy