|Da Como, E.; Borys, N.J.; Strohriegl, P.; Walter, M.J.; Lupton, J.M.: Formation of a Defect-Free pi-Electron System in Single beta-Phase Polyfluorene Chains, Journal of the American Chemical Society 133(11), 3690-3692 (2011) -- DOI: 10.1021/ja109342t
Single-molecule spectroscopy can help to uncover the underlying heterogeneity of conjugated polymers used in organic electronics, revealing the most effective molecules in an ensemble in terms of the transport of charge and excitation energy. We demonstrate that beta-phase polyfluorene chains can form a near-perfect pi-electron system, whereas conventional polymers exhibit chromophoric localization due to perturbation of the conjugation. Broad-band excitation spectroscopy demonstrates that only one absorbing and emitting unit is present on the polymer chain with an average length of similar to 500 repeat units, illustrating that the material effectively behaves as a molecular quantum wire with strong electronic coupling throughout the entire system.