Beyond the adiabatic limit: Charge photogeneration in organic photovoltaic materials

Ryan D. Pensack, John B. Asbury

Research output: Contribution to journalArticlepeer-review

100 Scopus citations


Mounting evidence suggests that excess energy in charge-transfer (CT) excitonic states facilitates efficient charge separation in organic solar cells. Experimental and theoretical studies have revealed that this excess energy may reside in phonon modes or in electronic coordinates of organic photovoltaic materials that are directly excited by the transition from Frenkel to CT excitons. Despite their strong Coulombic attraction, electron-hole pairs in hot CT excitons are able to undergo activationless separation because the rate of separation competes with thermalization of electronic and nuclear degrees of freedom. We argue that these observations indicate strong coupling of the dynamics of electronic and nuclear coordinates in organic photovoltaic materials. Thus, a nonadiabatic description is needed to properly understand the mechanism of charge photogeneration in organic solar cells. Such a description will support continuing efforts toward the development of low-band-gap organic solar cells that efficiently generate photocurrent with minimal energy losses.

Original languageEnglish (US)
Pages (from-to)2255-2263
Number of pages9
JournalJournal of Physical Chemistry Letters
Issue number15
StatePublished - Aug 5 2010

All Science Journal Classification (ASJC) codes

  • General Materials Science
  • Physical and Theoretical Chemistry


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