We show here that treatment of thin films of conjugated polymers by illumination with light leads to an increase of the intensity of their photoluminescence by up to 42%. The corresponding enhancement of absorbance was much less pronounced. We explain this significant enhancement of photoluminescence by a planarization of the conjugated polymer chains induced by photoexcitations even below the glass transition temperature, possibly due to an increased conjugation length. Interestingly, the photoluminescence remains at the enhanced level for more than 71 h after treatment of the films by illumination with light, likely due to the fact that below the glass transition temperature no restoring force could return the conjugated chains into their initial conformational state. © 2014 American Chemical Society.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): CRG-1-2012-THO-015
Acknowledgements: I.B. thanks Anna Köhler, Eric Bittner, David Vanden Bout, Carlos Silva, Werner Stille, Günter Reiter, and Chung Wing Tsoi for fruitful discussions. I.B. and N.S. acknowledge financial support by the Deutsche Forschungsgemeinschaft through the Freiburg Institute for Advanced Studies (FRIAS). In addition, N.S. acknowledges her support by a European Research Council (ERC) Starting Independent Researcher Fellowship under the grant agreement No. 279587 and KAUST Competitive Research Grant (CRG-1-2012-THO-015).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.