Photovoltaic charge generation in organic semiconductors based on long-range energy transfer

David C. Coffey, Andrew J. Ferguson, Nikos Kopidakis, Garry Rumbles*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)


For efficient charge generation in organic solar cells, photogenerated excitons must migrate to a donor/acceptor interface where they can be dissociated. This migration is traditionally presumed to be based on diffusion through the absorber material. Herein we study an alternative migration route-two-step exciton dissociation-whereby the exciton jumps from the donor to acceptor before charge creation takes place. We study this process in a series of multilayer donor/barrier/acceptor samples, where either poly(3- hexylthiophene) (P3HT) or copper phthalocyanine (CuPc) is the donor, fullerene (C60) is the acceptor, and N,N-diphenyl-N,N-bis(3-methylphenyl)-[1,1- bisphenyl]-4,4-diamine (TPD) acts as a barrier to energy transfer. By varying the thickness of the barrier layer, we find that energy transfer from P3HT to C60 proceeds over large distances (∼50% probability of transfer across a 11 nm barrier), and that this process is consistent with long-range Förster resonance energy transfer (FRET). Finally, we demonstrate a fundamentally different architecture concept that utilizes the two-step mechanism to enhance performance in a series of P3HT/CuPc/C60 devices.

Original languageEnglish
Pages (from-to)5437-5445
Number of pages9
JournalACS Nano
Issue number9
Publication statusPublished - 28 Sept 2010
Externally publishedYes


  • charge transfer
  • energy transfer
  • Förster
  • FRET
  • microwave conductivity
  • organic semiconductor
  • photovoltaic
  • solar cell


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