title: Increasing the open circuit voltage of bulk-heterojunction solar cells by raising the LUMO level of the acceptor.
abstract: We report the synthesis, characterization, and electrochemical properties of ten new fullerene derivatives for usage in organic solar cells. The phenyl ring of PCBM was substituted with electron-donating and electron-withdrawing substituents to study their influence on the LUMO level of the parent fullerene. We varied the LUMO level over a range of 86 mV and show a small but significant change of the open circuit voltage upon application in MDMO-PPV:methanofullerene bulk-heterojunction photovoltaic cells. [structure: see text].
authors.affiliation: Molecular Electronics, Materials Science CentrePlus, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: Floris B
authors.initials: FB
authors.lastname: Kooistra
authors.forename: Joop
authors.initials: J
authors.lastname: Knol
authors.forename: Fredrik
authors.initials: F
authors.lastname: Kastenberg
authors.forename: Lacramioara M
authors.initials: LM
authors.lastname: Popescu
authors.forename: Wiljan J H
authors.initials: WJ
authors.lastname: Verhees
authors.forename: Jan M
authors.initials: JM
authors.lastname: Kroon
authors.forename: Jan C
authors.initials: JC
authors.lastname: Hummelen