Universität zu Köln

Brueckner, Charlotte, Wuerthner, Frank, Meerholz, Klaus ORCID: 0000-0001-7450-4672 and Engels, Bernd ORCID: 0000-0003-3057-389X (2017). Atomistic Approach To Simulate Processes Relevant for the Efficiencies of Organic Solar Cells as a Function of Molecular Properties. II. Kinetic Aspects. J. Phys. Chem. C, 121 (1). S. 26 - 52. WASHINGTON: AMER CHEMICAL SOC. ISSN 1932-7447

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Abstract

The individual steps of the light-to-energy conversion process in the vicinity of the interfaces of organic solar cells are investigated with kinetic Monte Carlo simulations employing Marcus hopping rates obtained from quantum-chemical calculations. A chemically diverse set of p-type semiconducting molecules in heterojunction with fullerene C-60 is used. Starting with exciton diffusion, exciton dissociation, charge generation, and charge separation are modeled on an atomistic level. Numerous aspects were already analyzed, but comprehensive simulations including all three processes in amorphous model interface systems and a comparison of various different molecular p-type semiconductors seem to be missing. Our investigation identifies several important kinetic effects that could limit device efficiencies, such as the strong reduction of charge transport rates in the vicinity of the interface due to Coulomb interactions between the charges, the importance of adjusting the relative rates of exciton transfer and dissociation, and the impact of morphology. Charge drift velocities and hole mobilities obtained from the simulations compare well with experimental values indicating that the main effects are covered by the simulations. A correlation between experimental short-circuit currents and simulated charge drift velocities suggests that slow charge-transfer processes could represent a major efficiency-limiting parameter in organic solar cells.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Brueckner, Charlotte UNSPECIFIED UNSPECIFIED UNSPECIFIED Wuerthner, Frank UNSPECIFIED UNSPECIFIED UNSPECIFIED Meerholz, Klaus UNSPECIFIED orcid.org/0000-0001-7450-4672 UNSPECIFIED Engels, Bernd UNSPECIFIED orcid.org/0000-0003-3057-389X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-242562
DOI:	10.1021/acs.jpcc.6b11340
Journal or Publication Title:	J. Phys. Chem. C
Volume:	121
Number:	1
Page Range:	S. 26 - 52
Date:	2017
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 CHARGE-TRANSFER STATES; MONTE-CARLO SIMULATIONS; POLYMER-FULLERENE HETEROJUNCTIONS; ELECTRONICALLY EXCITED-STATES; TIME-RESOLVED FLUORESCENCE; EXCITATION-ENERGY TRANSFER; DONOR-ACCEPTOR CONJUGATE; DENSITY-OF-STATES; HIGH FILL FACTOR; DIFFERENTIAL-OVERLAP Multiple languages Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/24256