Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 68: Photovoltaics: Organic Semiconductors
HL 68.7: Talk
Wednesday, March 28, 2012, 19:15–19:30, ER 270
Thermodynamic efficiency limit of molecular donor-acceptor solar cells and its application to diindenoperylene (DIP)-based devices — •Mark Gruber1, Julia Wagner1, Ulrich Hörmann1, Andreas Opitz2, and Wolfgang Brütting1 — 1Institute of Physics, University of Augsburg, Germany — 2Institute of Physics, Humboldt University, Berlin, Germany
Based on the principle of detailed balance we have developed a modified Shockley-Queisser theory including the effects of interfacial charge transfer (CT) states that allows for a quantitative assessment of the thermodynamic efficiency limits of molecular donor(D)/acceptor(A) solar cells. Key parameters entering the model, apart from the optical gap of the absorber material, are the energy (ECT) and relative absorption strength (αCT) of the CT state. We demonstrate how the open-circuit voltage and thus the power conversion efficiency are affected by different parameter values. Furthermore, we show that temperature dependent device characteristics can serve to determine the CT energy, and thus the upper limit of VOC for a given D/A combination, as well as to quantify non-radiative recombination losses. The model is applied to DIP based photovoltaic devices, where open-circuit voltages between 0.9 and 1.4 V, depending on the partner, have recently been reported [1,2].
J. Wagner et al., Adv. Func. Mater. 2010, 20, 4295.
U. Hörmann et al., Phys. Stat. Sol. RRL 2011, 5, 241.