Variable charge transfer state energies at nanostructured pentacene/C60 interfaces

While it has recently been recognized that organic donor-acceptor charge transfer (CT) state energies can vary substantially under different interfacial morphologies, this behavior is under-appreciated in the context of organic singlet fission solar cells where a specific alignment between the tripl...

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Veröffentlicht in:Applied physics letters 2018-05, Vol.112 (21)
Hauptverfasser: Lin, YunHui L., Zhang, Fengyu, Kerner, Ross A., Yang, Terry Chien-Jen, Kahn, Antoine, Rand, Barry P.
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Sprache:eng
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Zusammenfassung:While it has recently been recognized that organic donor-acceptor charge transfer (CT) state energies can vary substantially under different interfacial morphologies, this behavior is under-appreciated in the context of organic singlet fission solar cells where a specific alignment between the triplet state of the fission material and the CT state of the donor-acceptor interface is necessary to the function of the device. In this work, we demonstrate that the CT state energy of a prototypical pentacene-C60 singlet fission system is around 1 eV in most systems, but can vary over 300 meV depending on the composition and morphology of the interface. Moreover, we show that the inclusion of a poly(3-hexylthiophene-2,5-diyl) underlayer, which commonly serves as a triplet blocker and hole collector in pentacene/C60 solar cells, helps promote active layer morphologies with stabilized, low energy CT states. These trends in the interfacial energetics are correlated with structural characterization of the films by atomic force microscopy and x-ray diffraction.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.5030885