Electron Affinity of Phenyl-C61-Butyric Acid Methyl Ester (PCBM)

Bryon W. Larson, James B. Whitaker, Xue Bin Wang, Alexey A. Popov, Garry Rumbles, Nikos Kopidakis, Steven H. Strauss, Olga V. Boltalina

Research output: Contribution to journalArticlepeer-review

89 Scopus Citations


The gas-phase electron affinity (EA) of phenyl-C61-butyric acid methyl ester (PCBM), one of the best-performing electron acceptors in organic photovoltaic devices, was measured by low-temperature photoelectron spectroscopy for the first time. The obtained value of 2.63(1) eV is only ca. 0.05 eV lower than that of C60 (2.683(8) eV), compared to a 0.09 V difference in their E1/2 values measured in this work by cyclic voltammetry. Literature E(LUMO) values for PCBM that are typically estimated from cyclic voltammetry and commonly used as a quantitative measure of acceptor properties are dispersed over a wide range between -4.38 and -3.62 eV; the reasons for such a huge discrepancy are analyzed here, and a protocol for reliable and consistent estimations of relative fullerene-based acceptor strength in solution is proposed.

Original languageAmerican English
Pages (from-to)14958-14964
Number of pages7
JournalJournal of Physical Chemistry C
Issue number29
StatePublished - 25 Jul 2013

NREL Publication Number

  • NREL/JA-5900-60499


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