Conjugated copolymers with novel low bandgap rhenium(I) complexes on the polymer main-chain are reported. The low bandgap metal-containing polymers were synthesized by Suzuki cross-coupling polycondensation or Stille coupling polymerization. The metal free copolymers are conjugatively-linked with functionalized intramolecular charge transfer units, which exhibited prominent absorption band in the UV-vis region. These functionalized charge transfer units not only broadened the absorption spectrum, but also functioned as a bidentate ligand. Upon the complexation of rhenium(I) pentacarbonyl chloride, the absorption spectrum of the resulting polymers was further boardened, and the bandgap was reduced. The material design of this work has opened up a new approach in developing low bandgap metal-containing polymers as light harvesting materials.

A new synthetic route to novel ruthenium-containing polymers is reported. [Ru(L)(L')Cl(2)] type complexes (L and L' = bidentate N^N ligands) with a dibromo-substituted ligand were polymerized by Stille cross-coupling reaction. The subsequent displacement of chloride ligands by thiocyanate was highly effective and the structures of the target polymers were fully characterized. The main chain absorption showed a significantly red-shift upon metal coordination and the metal-to-ligand charge transfer (MLCT) band of the complex enhanced the photon harvesting ability of the polymer. The extent of π-electron delocalization of the ancillary ligands also showed interesting effects on the electronic properties of the polymers. The photosensitizing and bandgap tuning properties of these Ru(II) complexes demonstrated a new avenue to develop new classes of optoelectronic materials.

We have studied the properties of organic and organometallic polymers based on a similar chemical structure to elucidate the influence of the metal center on the optical and electronic properties of the polymers as well as their photovoltaic performance. Detailed characterization of the optical properties of both polymers is performed and film morphology and photovoltaic performance are compared. Metal‐containing polymers exhibit red‐shifted absorption and under optimal processing conditions exhibit different film morphology compared with the metal‐free ones. Our results indicate that organometallic polymers represent a promising class of compounds for improved performance in photovoltaic cells.

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