title: Real-Time Tracking of Singlet Exciton Diffusion in Organic Semiconductors.
abstract: Exciton diffusion in organic materials provides the operational basis for functioning of such devices as organic solar cells and light-emitting diodes. Here we track the exciton diffusion process in organic semiconductors in real time with a novel technique based on femtosecond photoinduced absorption spectroscopy. Using vacuum-deposited C_{70} layers as a model system, we demonstrate an extremely high diffusion coefficient of D≈3.5×10^{-3}  cm^{2}/s that originates from a surprisingly low energetic disorder of <5  meV. The experimental results are well described by the analytical model and supported by extensive Monte Carlo simulations. The proposed noninvasive time-of-flight technique is deemed as a powerful tool for further development of organic optoelectronic components, such as simple layered solar cells, light-emitting diodes, and electrically pumped lasers.
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, 9747AG Groningen, The Netherlands.|Faculty of Physics and International Laser Center, Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Kozlov
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, 9747AG Groningen, The Netherlands.
authors.forename: Foppe
authors.initials: F
authors.lastname: de Haan
authors.affiliation: Department of Electrical Engineering and Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Ross A
authors.initials: RA
authors.lastname: Kerner
authors.affiliation: Department of Electrical Engineering and Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: Barry P
authors.initials: BP
authors.lastname: Rand
authors.affiliation: IMEC, Kapeldreef 75, B-3001 Leuven, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Cheyns
authors.affiliation: Zernike Institute for Advanced Materials, University of Groningen, 9747AG Groningen, The Netherlands.
authors.forename: Maxim S
authors.initials: MS
authors.lastname: Pshenichnikov