Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 113: Organic Electronics and Photovoltaics: Devices (jointly with CPP, HL)
TT 113.6: Talk
Friday, March 20, 2015, 11:15–11:30, C 130
Influence of Molecular Orientation on the Coupling of Excitons to Surface Plasmons in Semitransparent Inverted Organic Solar Cells — •Mark Gruber, Michael Mayr, Björn Gallheber, and Wolfgang Brütting — Institute for Physics, University of Augsburg, Germany
To prove the principle of coupling between surface plasmons (SPs) and excitons, we investigated semi-transparent organic solar cells, in which SPs are excited at interfaces of thin metal films and a dielectric medium by using a Kretschmann configuration setup. Therefore it is essential, that the dielectric medium has a smaller refractive index than glass, e.g. LiF or air.
To compare the SP coupling to different orientations of the transition dipole moment, two donor materials were used, diindenoperylene (DIP) and dibenzo-tetraphenyl-periflanthen (DBP). Both molecules have the transition dipole moment along the long axis. While DIP crystallizes with nearly upright standing molecules on the underlying PCBM film, DBP grows amorphous with predominantly lying molecules.1,2 To locate the angular position of the SP resonance the reflectance of the OPVC is measured angle dependent. A simultaneously measured photo current reveals the impact of SPs in these OPVCs. The use of different donors shows, that coupling from SPs to excitons only leads to a positive effect for upright-standing transition dipole moment orientation.
1 Wagner et al., Adv. Func. Mater. 20, 4295, 2010.
2 Grob et al., Appl. Phys. Lett. 104, 213304, 2014.