Wilke, A.; Endres, J.; Hörmann, U.; Niederhausen, J.; Schlesinger, R.; Frisch, J.; Amsalem, P.; Wagner, J.; Gruber, M.; Opitz, A.; Vollmer, A.; Brütting, W.; Kahn, A.; Koch, N.: Correlation between interface energetics and open circuit voltage in organic photovoltaic cells. Applied Physics Letters 101 (2012), p. 233301/1-4
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We have used ultraviolet and inverse photoemission spectroscopy to determine the transport gaps (E-t) of C-60 and diindenoperylene (DIP), and the photovoltaic gap (E-PVG) of five prototypical donor/acceptor interfaces used in organic photovoltaic cells (OPVCs). The transport gap of C-60 (2.5 +/- 0.1) eV and DIP (2.55 +/- 0.1) eV at the interface is the same as in pristine films. We find nearly the same energy loss of ca 0.5 eV for all material pairs when comparing the open circuit voltage measured for corresponding OPVCs and E-PVG. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769360]