Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 6: Poster: Structural Ordering and Electronic Transport (joint focus with HL)
CPP 6.3: Poster
Montag, 26. März 2012, 17:30–19:30, Poster A
Recombination process in organic photovoltaic solar cells based on BTD/DPP copolymers studied by IV-characteristics — •Olesia Synooka1, Chetan Raj Singh1, Florian Kretschmer2,3, Martin D. Hager2,3,4, Gerhard Gobsch1, and Harald Hoppe1 — 1Physics institute,TU Ilmenau, 98693 Ilmenau, Germany — 2Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich-Schiller-University Jena, Humboldtstr. 10, 07743 Jena, Germany — 3Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Humboldtstr. 10, 07743 Jena, Germany — 4Dutch Polymer Institute (DPI), John F. Kennedylaan 2, 5612 AB Eindhoven, The Netherlands
The short-circuit current density (Jsc) of polymer/fullerene bulk heterojunction solar cells based on benzothiadiazole (BTD) and/or diketopyrrolopyrrole (DPP) is investigated as a function of light intensity. The influence of light intensity and recombination strength on Jsc is consistently explained by a model based on the notion that the quasi-Fermi levels are constant throughout the device, including both drift and diffusion of charge carriers. A typical feature of polymer/fullerene based solar cells is that Jsc does not scale exactly linearly with light intensity (I). Instead, a power law relationship is found given by Jsc(Ia), where a ranges from 0.7 to 0.8. In a number of reports this deviation from unity is attributed to the occurrence of bimolecular recombination. Here is demonstrated the model calculations which shows that bimolecular recombination leads not a 100% of a typical loss of all free charge carriers at Jsc for these devices but it also governed by the build-up of space charge in the device.