Free Carrier Generation in Fullerene Acceptors and Its Effect on Polymer Photovoltaics

George F. Burkhard, Eric T. Hoke, Zach M. Beiley, Michael D. McGehee

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


Early research on C60 led to the discovery that the absorption of photons with energy greater than 2.35 eV by bulk C60 produces free charge carriers at room temperature. We find that not only is this also true for many of the soluble fullerene derivatives commonly used in organic photovoltaics, but also that the presence of these free carriers has significant implications for the modeling, characterization, and performance of devices made with these materials. We demonstrate that the discrepancy between absorption and quantum efficiency spectra in P3HT:PCBM is due to recombination of such free carriers in large PCBM domains before they can be separated at a donor/acceptor interface. Since most theories assume that all free charges result from the separation of excitons at a donor/acceptor interface, the presence of free carrier generation in fullerenes can have a significant impact on the interpretation of data generated by numerous field-dependent techniques. © 2012 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)26674-26678
Number of pages5
JournalThe Journal of Physical Chemistry C
Issue number50
StatePublished - Dec 5 2012
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by the Center for Advanced Molecular Photovoltaics (Award KUS-C1-015-21), made by King Abdullah University of Science and Technology (KAUST). E.T.H. was supported by the National Science Foundation GRFP and the Fannie and John Hertz Foundation. We thank Rodrigo Noriega and Alberto Salleo for help with the PDS measurements and Koen Vandewal for his insights.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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