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Monte Carlo Simulation of Geminate Pair Recombination Dynamics in Organic Photovoltaic Devices: Multi-Exponential, Field-Dependent Kinetics and Its Interpretation

Jones, L.M.; Chakrabarti, B.; Groves, C.

Monte Carlo Simulation of Geminate Pair Recombination Dynamics in Organic Photovoltaic Devices: Multi-Exponential, Field-Dependent Kinetics and Its Interpretation Thumbnail


Authors

L.M. Jones

B. Chakrabarti



Abstract

Monte Carlo simulations are used to examine charge-transfer (CT) state recombination dynamics considering the effects of energetic disorder and bulk heterojunction morphology. Strongly biexponential recombination kinetics were observed, in agreement with spectroscopy. Data over a range of electric fields 106 ≤ F ≤ 108 V m–1 suggest that the slow component of recombination is due to energetic and spatial trapping of charges, as increasing the field reduces the magnitude of the slow decay. This behavior could not be described using a simple Onsager–Braun type model; hence, an alternative kinetic framework including an intermediate “quasi-free” state between the CT state and free charges is proposed and subsequently shown to fit the MC data very well. The predictive capability of the modified model was then tested by repeating MC simulations with an altered recombination rate. It is shown that more than just the recombination rate had to be changed in the modified kinetic model to retrieve good agreement with MC simulations. This suggests that the derived rates from the modified kinetic model do not have exact correspondence with physical processes in organic photovoltaic blends. We attribute the difficulty in fitting kinetic models to CT recombination data to the dispersive nature of hopping transport.

Citation

Jones, L., Chakrabarti, B., & Groves, C. (2014). Monte Carlo Simulation of Geminate Pair Recombination Dynamics in Organic Photovoltaic Devices: Multi-Exponential, Field-Dependent Kinetics and Its Interpretation. Journal of Physical Chemistry C, 118(1), 85-91. https://doi.org/10.1021/jp408063f

Journal Article Type Article
Acceptance Date Sep 24, 2014
Online Publication Date Jan 9, 2014
Publication Date Jan 9, 2014
Deposit Date Jun 5, 2013
Publicly Available Date Mar 18, 2014
Journal Journal of Physical Chemistry C
Print ISSN 1932-7447
Electronic ISSN 1932-7455
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 118
Issue 1
Pages 85-91
DOI https://doi.org/10.1021/jp408063f
Public URL https://durham-repository.worktribe.com/output/1451328

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Publisher Licence URL
http://creativecommons.org/licenses/by/4.0/

Copyright Statement
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.






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