Influence of molecular orientation on the coupling of surface plasmons to excitons in semitransparent inverted organic solar cells

Abstract

We investigate the coupling between surface plasmons and excitons for different donor materials in semitransparent organic solar cells. Surface plasmons can be excited at the interface between the semitransparent anode and the surrounding dielectric medium in Kretschmann configuration, if the resonance condition for wavelength and angle is fulfilled. In solar cells with nearly upright standing diindenoperylene donor molecules in close proximity to the metal, this can lead to an enhancement in photo-current. By contrast, for cells with dibenzo-tetraphenyl-periflanthen as donor, the lying orientation of molecules is unfavorable for coupling to surface plasmons. In this case, the excitation of surface plasmons acts like a parasitic absorption and reduces the photo-current.