Charge generation pathways in organic solar cells: assessing the contribution from the electron acceptor

Stoltzfus, Dani M., Donaghey, Jenny E., Armin, Ardalan, Shaw, Paul E., Burn, Paul L. and Meredith, Paul (2016) Charge generation pathways in organic solar cells: assessing the contribution from the electron acceptor. Chemical Reviews, 116 21: 12920-12955. doi:10.1021/acs.chemrev.6b00126


Author Stoltzfus, Dani M.
Donaghey, Jenny E.
Armin, Ardalan
Shaw, Paul E.
Burn, Paul L.
Meredith, Paul
Title Charge generation pathways in organic solar cells: assessing the contribution from the electron acceptor
Journal name Chemical Reviews   Check publisher's open access policy
ISSN 1520-6890
0009-2665
Publication date 2016-11-09
Year available 2016
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1021/acs.chemrev.6b00126
Open Access Status Not yet assessed
Volume 116
Issue 21
Start page 12920
End page 12955
Total pages 36
Place of publication Washington, DC, United States
Publisher American Chemical Society
Language eng
Abstract Photocurrent generation in organic bulk heterojunction (BHJ) solar cells is most commonly understood as a process which predominantly involves photoexcitation of the lower ionization potential species (donor) followed by electron transfer to the higher electron affinity material (acceptor) [i.e., photoinduced electron transfer (PET), which we term Channel I]. A mirror process also occurs in which photocurrent is generated through photoexcitation of the acceptor followed by hole transfer to the nonexcited donor or photoinduced hole transfer (PHT), which we term Channel II. The role of Channel II photocurrent generation has often been neglected due to overlap of the individual absorption spectra of the donor and acceptor materials that are commonly used. More recently Channel II charge generation has been explored for several reasons. First, many of the new high-efficiency polymeric donors are used as the minority component in bulk heterojunction blends, and therefore, the acceptor absorption is a significant fraction of the total; second, nonfullerene acceptors have been prepared, which through careful design, allow for spectral separation from the donor material, facilitating fundamental studies on charge generation. In this article, we review the methodologies for investigating the two charge generation channels. We also discuss the factors that affect charge generation via Channel I and II pathways, including energy levels of the materials involved, exciton diffusion, and other considerations. Finally, we take a comprehensive look at the nonfullerene acceptor literature and discuss what information about Channel I and Channel II can be obtained from the experiments conducted and what other experiments could be undertaken to provide further information about the operational efficiencies of Channels I and II.
Keyword Chemistry, Multidisciplinary
Chemistry
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collections: Centre for Organic Photonics and Electronics
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