Dresden 2017 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 88: Organic Electronics and Photovoltaics V: OPV

HL 88.2: Talk

Friday, March 24, 2017, 10:30–10:45, ZEU 255

Quantifying Coupling Rate Constants of Bound Charges to the Ground State and Free Charges in Organic Semiconductors — •Safa Shoaee¹, Martin Stolterfoht¹, and Ardalan Armin² — ¹Institute for Physics and Astronomy, University of Potsdam, Potsdam, Germany — ²School of Mathematics and Physics, University of Queensland, Australia

Bimolecular recombination of the free charges in the donor/acceptor organic solar cells has been considered as the main loss mechanism. For very few donor/acceptor systems the bimolecular recombination rate constant is shown to be lower than what predicted by the classic Langevin model. We and others have recently shown that this suppression may originate from weaker coupling rate of the so called interfacial charge transfer states to the ground state [Burk et al. AEM 2015, Armin et al. AEM 2016]. In Particular we have shown that recombination can be 150 times less than that predicted by Langevin model, resulting in efficiencies as high as 9%, at junction > 300 nm. These studies show the importance of the kinetic constants of the charge transfer states. Recently we have developed methodology to quantify these kinetic rates as well as charge generation efficiency in organic photovoltaic systems [Stolterfoht, Shoaee et al. Nature Comm 2016, Shoaee et al. Unpublished results], as well as determining the kinetic rate constants of the charge transfer states. These are pathway towards better understanding donor acceptor solar cells and optimise their photovoltaic performance for better efficiencies.