Determination of quasi-fermi levels across illuminated organic donor/acceptor heterojunctions by kelvin probe force microscopy

David J. Ellison, Jung Yong Kim, Derek M. Stevens, C. Daniel Frisbie

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Using Kelvin probe force microscopy (KFM), we have measured the electrochemical potentials across indium tin oxide/organic and donor/acceptor heterojunctions in the dark and under illumination with white light. We have found that the photovoltage generated across these heterojunctions is strongly correlated with the difference between the respective HOMO and LUMO levels of the donor and acceptor and also very closely approximates measured open-circuit voltages in completed solar cells. These results imply that KFM tracks the Fermi level positions within the donor and acceptor layers under photoexcitation. Overall, these results demonstrate the utility of KFM for understanding potential profiles across active layers in planar-heterojunction organic solar cells.

Original languageEnglish (US)
Pages (from-to)13802-13805
Number of pages4
JournalJournal of the American Chemical Society
Volume133
Issue number35
DOIs
StatePublished - Sep 7 2011

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