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Issue 5, 2012
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Exciton diffusion length in narrow bandgap polymers

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We developed a new method to accurately extract the singlet exciton diffusion length in organic semiconductors by blending them with a low concentration of methanofullerene[6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The dependence of photoluminescence (PL) decay time on the fullerene concentration provides information on both exciton diffusion and the nanocomposition of the blend. Experimentally measured PL decays of blends based on two narrow band gap dithiophene–benzothiadiazole polymers, C–PCPDTBT and Si–PCPDTBT, were modeled using a Monte Carlo simulation of 3D exciton diffusion in the blend. The simulation software is available for download. The extracted exciton diffusion length is 10.5 ± 1 nm in both narrow band gap polymers, being considerably longer than the 5.4 ± 0.7 nm that was measured with the same technique in the model compound poly(3-hexylthiophene) as a reference. Our approach is simple, fast and allows us to systematically measure and compare exciton diffusion length in a large number of compounds.

Graphical abstract: Exciton diffusion length in narrow bandgap polymers

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The article was received on 14 Dec 2011, accepted on 10 Feb 2012 and first published on 10 Feb 2012

Article type: Paper
DOI: 10.1039/C2EE03466B
Citation: Energy Environ. Sci., 2012,5, 6960-6965
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    Exciton diffusion length in narrow bandgap polymers

    O. V. Mikhnenko, H. Azimi, M. Scharber, M. Morana, P. W. M. Blom and M. A. Loi, Energy Environ. Sci., 2012, 5, 6960
    DOI: 10.1039/C2EE03466B

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