Using a series of acceptor-polymer-acceptor triads, IRG-2 investigators have measured intramolecular exciton diffusion in poly-3(hexylthiophene) (P3HT) for the first time. The results indicate that the transport is much more facile along the polymer chain than in ordered regions of thin films where intermolecular interactions trap the exciton. The intramolecular exciton diffusion length LD was found to be 7 nm. Exciton diffusivity was measured by determining the dependence of photo-luminescence quenching of C60-endcapped P3HT as a function of polymer chain length, followed by theoretical modeling. The results have implications for the use of P3HT (and other conjugated polymers) in organic solar cells.
