Acceptor Energy Offset Manages Ultrafast Recombination Dynamics in Donor-Acceptor Mixtures
1 Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG Groningen, The Netherlands
2 Faculty of Physisc and International Laser Center, Lomonosov Moscow State University, Leninskie Gory, 119991, Moscow, Russia
3 L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, national Academy of Sciences of Ukraine, R. Luxemburg Street 70, Donetsk, 83122, Ukraine
4 School of Chemistry, Bangor University, Deiniol Road, Bangor, LL757, 2UW, United Kingdom
We study charge recombination rates in blends of MEH-PPV and a comprehensive set of low molecular-weight fluorine-based acceptors, using visible-pump - IR-probe photoinduced absorption technique. The positions of acceptor’s HOMO-LUMO levels are engineered by addition of different chemical substituents. The results clearly show the exponential scaling of the charge recombination rate with the acceptor LUMO energy. The minimal donor-acceptor LUMO energy difference required to form a CTC state is estimated as ∼ 0.25 eV.
© Owned by the authors, published by EDP Sciences, 2013
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