Synthesis, characterization and photophysical properties of rhenium(I)-containing polyfluorene-based copolymers

• Published in: Thin solid films 2005-04, Vol.477 (1), p.193-197
• Main Authors: Zhang, M., Lu, P., Wang, X.M., Xia, H., Zhang, W., Yang, B., Liu, L.L., Yang, L., Yang, M., Ma, Y.G., Feng, J.K., Wang, D.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Energy; Exact sciences and technology; MLCT; Natural energy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Phosphorescence; Photoelectric conversion: solar cells and arrays; Photoluminescence; Photovoltaic conversion; Photovoltaic devices; Physics; Rhenium(I); Solar cells. Photoelectrochemical cells; Solar energy; Solid organic materials
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2004.08.186

A new series of π-conjugated [2,7-(9,9′-dihexylfluorene)-co-alt-5,5′-(2,2′-bipyridine)] (fluorene-co-bpy) copolymers containing fac-(bpy)Re(I)(CO) 3Cl (bpy=2,2′-bipyridine, Re=rhenium) chromophores were synthesized and well characterized. The chelating copolymers showed characteristic MLCT absorption and emission at room temperature. Bonded Re complexes harvested excited energy efficiently through intra- and intermolecular energy from polymer backbone to Re complexes; however, both photoluminescence (PL) and electroluminescence (EL) efficiencies were unexpectedly lower. Such lower luminescent efficiency was conceivably related to charge carrier separation of localized electron-hole pairs (excitons) in fac-(bpy)Re(I)(CO) 3Cl, which was induced by extensive π-conjugation. Further studies of density functional theory (DFT) calculation and surface photovoltaic spectra (SPS) afford proofs of charge carrier separation in fac-(bpy)Re(I)(CO) 3Cl chelating polymers. The efficient charge carrier separation will decrease the efficiency of PL and EL but enhance the photovoltaic efficiency.