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Efficient Charge Generation Via Hole Transfer in Dilute Organic Donor-Fullerene Blends

preprint
submitted on 06.12.2019 and posted on 13.12.2019 by Yin Song, Alexander Schubert, Xiao Liu, Srijana Bhandari, Stephen R. Forrest, Barry D. Dunietz, Eitan Geva, Jennifer P. Ogilvie

Efficient organic photovoltaics (OPVs) require broadband charge photogeneration with near-unity quantum yield. This can only be achieved by exploiting all pathways that generate charge. Electron transfer from organic donors to acceptors has been well-studied and is considered the primary path to charge photogeneration in OPVs. In contrast, much less is known about the hole transfer pathway.

Here we study charge photogeneration in an archetypical system comprising tetraphenyldibenzoperiflanthene: C70 blends using our recently developed multispectral two dimensional electronic spectroscopy (M-2DES), supported by time-dependent density functional theory and fully quantum-mechanical Fermi’s golden rule rate calculations. Our approach identifies in real time two rapid charge transfer pathways that are confirmed through computational analysis. Surprisingly, we find that both electron and hole transfer occur with comparable rates and efficiencies, facilitated by donor-acceptor electronic interactions. Our results highlight the importance of the hole transfer pathway for optimizing the efficiency of OPV devices employing small-molecule heterojunctions.

History

Email Address of Submitting Author

songyi@umich.edu

Institution

University of Michigan

Country

US

ORCID For Submitting Author

0000-0001-8978-2958

Declaration of Conflict of Interest

no

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