Triplet formation in fullerene multi-adduct blends for organic solar cells and its influence on device performance

Clare Dyer-Smith, Luke X. Reynolds, Annalisa Bruno, Donal D.C. Bradley, Saif A. Hoque, Jenny Nelson

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

In organic solar cells, high open circuit voltages may be obtained by choosing materials with a high offset between the donor highest occupied molecular orbital (HOMO) and acceptor lowest unoccupied molecular orbital (LUMO). However, increasing this energy offset can also lead to photophysical processes that compete with charge separation. In this paper the formation of triplet states is addressed in blends of polyfluorene polymers with a series of PCBM multi-adducts. Specifically, it is demonstrated that the formation of such triplets occurs when the offset energy between donor ionization potential and acceptor electron affinity is -1.6 eV or greater. Spectroscopic measurements support a mechanism of resonance energy transfer for triplet formation, influenced by the energy levels of the materials, but also demonstrate that the competition between processes at the donor-acceptor interface is strongly influenced by morphology. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Original languageEnglish (US)
JournalAdvanced Functional Materials
Volume20
Issue number16
DOIs
StatePublished - Aug 23 2010
Externally publishedYes

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