Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 21: Organic Electronics and Photovoltaics IV (joint session with CPP, HL, O)

DS 21.5: Talk

Wednesday, April 2, 2014, 10:30–10:45, ZEU 260

Radiative and non-radiative recombination in organic solar cells — •Kristofer Tvingstedt, Philip Pelchmann, Vladimir Dyakonov, and Carsten Deibel — Experimental Physics VI Julius Maximilian University of Würzburg 97074 Würzburg

Although several organic solar cells has reached close to unity internal quantum efficiency at short circuit conditions, the open circuit voltage is still very far from its potential upper limit due to substantial charge recombination of various types, which remains to be accurately determined. In this work we evaluate the limiting mechanisms in OPVs by employing complementary steady state measurements of recombination as a function of charge carrier density by thoroughly evaluating the diode ideality factor. The diode ideality is directly related to the order of recombination and we first assess it via light intensity dependent open circuit voltage characterization under the influence of a varying temperature. We focus our study on the ratio between radiative and non-radiative recombination via the interfacial charge transfer state as determined by absolute CT electroluminescence efficiency measurements, also as a function of temperature. The charge transfer state governs the radiative recombination in OPV bulk heterojunctions and is therefore crucial to evaluate in this context. Improving the radiative efficiency of OPVs will substantially increase the open circuit voltage and eventually put these promising photovoltaic converters in efficiency parity with their inorganic counterparts.