Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 65: Poster: Organic electronics and photovoltaics (CPP; jointly with HL, O)
HL 65.10: Poster
Wednesday, March 13, 2013, 16:30–18:30, Poster C
Absorption and exciton management in DIP/C60 bilayer photovoltaic cells — •A. Steindamm1,2, M. Brendel1,2, K. Topczak1, and J. Pflaum1,2 — 1Exp. Phys. VI, University of Würzburg, 97074 Würzburg — 2ZAE Bayern, 97074 Würzburg
The combination of the promising material Diindenoperylene (DIP) with the acceptor C60 has led to overall efficiencies up to 4 % in organic photovoltaic cells (OPVCs) [1]. A drawback in performance is found in the rather poor light absorption of the crystalline DIP layer due to its unfavorable orientation of transition dipoles perpendicular to the electric field vector of incident light. Therefore we pursued different approaches for increasing the current density. First, the orientation of the individual DIP molecules was altered by varying the growth conditions in order to increase light absorption. Second, the interface effects of an Bathophenanthroline (BPhen) exciton blocking layer (EBL) on the exciton management in DIP/C60 were investigated by a complementary study of current density, external quantum efficiency, and photoluminescence quenching for various EBL thicknesses. These investigations reveal exciton losses by contact metal quenching in both active layers if no EBL is applied. In contrast, an optimal trade-off between exciton blocking, suppression of metal penetration, and electron transport is achieved for a 5 nm thick BPhen layer yielding an improvement of power conversion efficiency by more than a factor of 2 [2]. Financial support by BMBF (GREKOS) and DFG (SPP1355) is acknowledged.
[1] A. Opitz, et al., IEEE J. Sel. Top. Quant. El. 16, 1707 (2010)
[2] A. Steindamm, et al., Appl. Phys. Lett. 101, 143302 (2012)