Probing the pathways of free charge generation in organic bulk heterojunction solar cells.

Autor:	Kurpiers J; Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany., Ferron T; Department of Physics and Astronomy, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA., Roland S; Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany., Jakoby M; Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology (IMT), Hermann-von-Helmholtz Platz-1, 76344, Eggenstein-Leopoldshafen, Germany., Thiede T; Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany., Jaiser F; Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany., Albrecht S; Helmholtz-Zentrum Berlin für Materialien und Energie, Nachwuchsgruppe Perowskit Tandemsolarzellen, Kekuléstraße 5, 12489, Berlin, Germany., Janietz S; Fraunhofer IAP, Polymere und Elektronik, Geiselbergstraße 69, 14476, Potsdam-Golm, Germany., Collins BA; Department of Physics and Astronomy, Washington State University, 100 Dairy Road, Pullman, WA, 99164, USA., Howard IA; Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology (IMT), Hermann-von-Helmholtz Platz-1, 76344, Eggenstein-Leopoldshafen, Germany., Neher D; Institute of Physics and Astronomy, Soft Matter Physics, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam-Golm, Germany. neher@uni-potsdam.de.
Jazyk:	angličtina
Zdroj:	Nature communications [Nat Commun] 2018 May 23; Vol. 9 (1), pp. 2038. Date of Electronic Publication: 2018 May 23.
DOI:	10.1038/s41467-018-04386-3
Abstrakt:	The fact that organic solar cells perform efficiently despite the low dielectric constant of most photoactive blends initiated a long-standing debate regarding the dominant pathways of free charge formation. Here, we address this issue through the accurate measurement of the activation energy for free charge photogeneration over a wide range of photon energy, using the method of time-delayed collection field. For our prototypical low bandgap polymer:fullerene blends, we find that neither the temperature nor the field dependence of free charge generation depend on the excitation energy, ruling out an appreciable contribution to free charge generation though hot carrier pathways. On the other hand, activation energies are on the order of the room temperature thermal energy for all studied blends. We conclude that charge generation in such devices proceeds through thermalized charge transfer states, and that thermal energy is sufficient to separate most of these states into free charges.
Databáze:	MEDLINE
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