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Missing Excitons: How Energy Transfer Competes with Free Charge Generation in Dilute-Donor/Acceptor Systems.
Carr, Joshua M; Gish, Melissa K; Reid, Obadiah G; Rumbles, Garry.
Affiliation
  • Carr JM; Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80303, United States.
  • Gish MK; Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
  • Reid OG; Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States.
  • Rumbles G; Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80303, United States.
ACS Energy Lett ; 9(3): 896-907, 2024 Mar 08.
Article in En | MEDLINE | ID: mdl-38482181
ABSTRACT
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.

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: ACS Energy Lett Year: 2024 Document type: Article Affiliation country: United States Country of publication: United States

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: ACS Energy Lett Year: 2024 Document type: Article Affiliation country: United States Country of publication: United States