The origin of charge localization observed in organic photovoltaic materials

James E. Johns, Eric A. Muller, Jean M.J. Frechet, Charles B. Harris

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Two of the primary hurdles facing organic electronics and photovoltaics are their low charge mobility and the inability to disentangle morphological and molecular effects on charge transport. Specific chemical groups such as alkyl side chains are often added to enable spin-casting and to improve overall power efficiency and morphologies, but their exact influence on mobility is poorly understood. Here, we use two-photon photoemission spectroscopy to study the charge transport properties of two organic semiconductors, one with and one without alkyl substituents (sexithiophene and dihexyl-sexithiophene). We show that the hydrocarbon side chains are responsible for charge localization within 230 fs. This implies that other chemical groups should be used instead of alkyl ligands to achieve the highest performance in organic photovoltaics and electronics.

Original languageEnglish (US)
Pages (from-to)15720-15725
Number of pages6
JournalJournal of the American Chemical Society
Issue number44
StatePublished - Nov 10 2010


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