Missing Excitons: How Energy Transfer Competes with Free Charge Generation in Dilute-Donor/Acceptor Systems
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- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States, Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80303, United States, Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States, Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States, Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80303, United States
Energy transfer across the donor-acceptor interface in organic photovoltaics is usually beneficial to device performance, as it assists energy transport to the site of free charge generation. Here, we present a case where the opposite is true: dilute donor molecules in an acceptor host matrix exhibit ultrafast excitation energy transfer (EET) to the host, which suppresses the free charge yield. We observe an optimal photochemical driving force for free charge generation, as detected via time-resolved microwave conductivity (TRMC), but with a low yield when the sensitizer is excited. Meanwhile, transient absorption shows that transferred excitons efficiently produce charge-transfer states. This behavior is well described by a competition for the excited state between long-range electron transfer that produces free charge and EET that ultimately produces only localized charge-transfer states. It cannot be explained if the most localized CT states are the intermediate between excitons and the free charge in this system.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
- Grant/Contract Number:
- AC36-08GO28308
- OSTI ID:
- 2320330
- Alternate ID(s):
- OSTI ID: 2323256
- Report Number(s):
- NREL/JA-5900-87537
- Journal Information:
- ACS Energy Letters, Journal Name: ACS Energy Letters Vol. 9 Journal Issue: 3; ISSN 2380-8195
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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