title: Efficiency of exciton and charge carrier photogeneration in a semiconducting polymer.
abstract: We determine the efficiencies for the formation of excitons and charge carriers following ultrafast photoexcitation of a semiconducting polymer (MEH-PPV). The simultaneous, quantitative determination of exciton and charge photoyields is achieved through subpicosecond studies of both the real and the imaginary components of the complex conductivity over a wide frequency range. Predominantly excitons, with near-unity quantum efficiency, are generated on excitation, while only a very small fraction (<10(-2)) of free charges are initially excited, consistent with rapid ( approximately 100 fs) hot exciton dissociation. These initial charges are very short lived, decaying on subpicosecond time scales.
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands. e.hendry@chem.leidenuniv.nl
authors.forename: E
authors.initials: E
authors.lastname: Hendry
authors.forename: J M
authors.initials: JM
authors.lastname: Schins
authors.forename: L P
authors.initials: LP
authors.lastname: Candeias
authors.forename: L D A
authors.initials: LD
authors.lastname: Siebbeles
authors.forename: M
authors.initials: M
authors.lastname: Bonn