Universität zu Köln

Augulis, Ramunas ORCID: 0000-0002-8596-2334, Devizis, Andrius, Peckus, Domantas ORCID: 0000-0002-4224-2521, Gulbinas, Vidmantas, Hertel, Dirk ORCID: 0000-0002-0421-9734 and Meerholz, Klaus ORCID: 0000-0001-7450-4672 (2015). High Electron Mobility and Its Role in Charge Carrier Generation in Merocyanine/Fullerene Blends. J. Phys. Chem. C, 119 (11). S. 5761 - 5771. WASHINGTON: AMER CHEMICAL SOC. ISSN 1932-7447

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Abstract

Charge carrier generation and drift dynamics have been investigated in two types of dye:fullerene heterojunctions: vacuum-deposited merocyanine:C-60 and solution-processed merocyanine:PC61BM blends by combining electric-field-induced fluorescence quenching and ultrafast time-resolved carrier drift measurements. We demonstrate that interfacial charge transfer (CT) states are strongly heterogeneous with energies dependent on the acceptor material and its domain sizes. Interfacial CT states on large C-60 domains have low energies, while CT states on PC61BM domains have larger energies, which are weakly dependent on the domain sizes. We distinguish two interfacial CT state dissociation pathways: (i) ultrafast, weakly dependent on the electric field and (ii) slow field-assisted dissociation during entire CT state lifetime. We attribute process i to low-energy, weakly bound CT states on large fullerene domains and process ii to strongly bound CT states on small domains or single fullerene molecules. The electron mobility in films with 50% of C-60 is several times higher than in the films with PC61BM and orders of magnitude higher than the hole mobility. We conclude that efficient carrier generation at low electric fields typical for operating solar cells relies on unperturbed motion of highly mobile electrons; thus, fast motion and extraction of electrons are crucial for efficient solar cells.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Augulis, Ramunas UNSPECIFIED orcid.org/0000-0002-8596-2334 UNSPECIFIED Devizis, Andrius UNSPECIFIED UNSPECIFIED UNSPECIFIED Peckus, Domantas UNSPECIFIED orcid.org/0000-0002-4224-2521 UNSPECIFIED Gulbinas, Vidmantas UNSPECIFIED UNSPECIFIED UNSPECIFIED Hertel, Dirk UNSPECIFIED orcid.org/0000-0002-0421-9734 UNSPECIFIED Meerholz, Klaus UNSPECIFIED orcid.org/0000-0001-7450-4672 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-404812
DOI:	10.1021/jp5054698
Journal or Publication Title:	J. Phys. Chem. C
Volume:	119
Number:	11
Page Range:	S. 5761 - 5771
Date:	2015
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1932-7447
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ORGANIC SOLAR-CELLS; TRANSFER EXCITONS; TRANSFER STATES; PHOTOCURRENT GENERATION; BULK HETEROJUNCTIONS; CONJUGATED POLYMER; DISSOCIATION; ENERGY; SEPARATION; FILMS Multiple languages Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/40481