Regensburg 2016 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 49: Organic Electronics and Photovoltaics II (joint session CPP/DS/HL/O, organized by CPP)
CPP 49.8: Vortrag
Donnerstag, 10. März 2016, 11:45–12:00, H40
Temperature dependent competition between different recombination channels in organic heterojunction solar cells — •Theresa Linderl, Ulrich Hörmann, Sergej Beratz, Mark Gruber, Stefan Grob, Alexander Hofmann, and Wolfgang Brütting — Institute of Physics, University of Augsburg, 86135 Augsburg
A modification of the Shockley-Queisser theory is presented with a special focus on constellations, where a linear extrapolation of the temperature dependence of the open circuit voltage VOC results in the optical gap of the absorber rather than in the intermolecular charge transfer (CT) gap. Depending on the electronic coupling strength between donor and acceptor molecules, either singlet or CT recombination is dominant in different temperature regimes. These regimes are separated by a transition temperature Ttr that is, in the case of small energy level offset and weak electronic coupling, around 300 K or even below. For α-sexithiophene (6T)/diindenoperylene (DIP) solar cells with elevated substrate temperature during 6T deposition the linear extrapolation of the temperature dependent VOC yields a value of 2.07 eV, whereas the extrapolation for the device evaporated at room temperature results in a value of 1.90 eV. Heating the substrate during 6T deposition leads to a molecular configuration at the interface where the coupling between donor and acceptor molecules is strongly reduced compared to the device evaporated at room temperature. This results in a transition temperature well below room temperature which is confirmed by temperature dependent electroluminescence measurements.