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Near-field photoconductivity imaging of a conjugated polymer blend

Published online by Cambridge University Press:  15 March 2011

R. Riehn
Affiliation:
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
R. Stevenson
Affiliation:
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
J.J.M. Halls
Affiliation:
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K.
D.R. Richards
Affiliation:
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K. Dept. of Physics, King's College London, Strand, London WC2R 2LS, England, U.K.
D.-J. Kang
Affiliation:
Department of Materials Science, University of Cambridge, Cambridge, U.K.
M. Blamire
Affiliation:
Department of Materials Science, University of Cambridge, Cambridge, U.K.
F. Cacialli
Affiliation:
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, U.K. Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, U.K.
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Abstract

We report combined scanning near-field optical microscopy (SNOM) and near-field photocurrent (NPC) imaging of a binary conjugated polymer blend. We find phase separation on a scale of about 5 μm, with a good correspondence between topographic, fluorescence, and photocurrent images. We excited at 488 nm, a wavelength at which only one of the two polymers absorbs light. Under this illumination regions that are high in the topography image show high luminescence and photocurrent.

The photoluminescence (PL) efficiencies in the different regions of the sample were determined by calculating the absorbed energy using the Bethe-Bouwkamp model, and knowledge about the chemical composition of the different phases of the polymer blend. The calculation also allowed us to conclude that the photocurrent generation efficiency (current/absorbed photons) of the different polymer phases is comparable within the limit of confidence of this experiment (±10 %).

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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References

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