Efficiency of exciton and charge carrier photogeneration in a semiconducting polymer.
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.
Hendry
E
E
Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands. e.hendry@chem.leidenuniv.nl
Schins
J M
JM
Candeias
L P
LP
Siebbeles
L D A
LD
Bonn
M
M