Charge pair dissociation and recombination dynamics in a P3HT–PC60BM bulk heterojunction

Andrew Barclay Matheson; Scott James Pearson; Arvydas Ruseckas; Ifor David William Samuel

doi:10.1021/jz4020426

Charge pair dissociation and recombination dynamics in a P3HT–PC₆₀BM bulk heterojunction

Andrew Barclay Matheson, Scott James Pearson, Arvydas Ruseckas, Ifor David William Samuel

Research output: Contribution to journal › Letter › peer-review

Abstract

The mechanism by which Coulombically bound charge pairs dissociate into free carriers in photovoltaic donor–acceptor blends is of great interest. Here, we use polarization-sensitive transient absorption (TA) to study the diffusion of photogenerated holes in a polythiophene (P3HT)–fullerene (PC₆₀BM) blend. We observe an initial anisotropy value of 0.4 for the absorption of photogenerated holes, indicating that holes generated on a 100 fs time scale are localized on the same polymer chain as their precursor excitons. Depolarization dynamics indicate fast initial hole motion on a 0.3 ps time scale and slower migration up to 100 ps. Charge pair recombination is found to occur on a much longer time scale of 10–1000 ns via a purely bimolecular process independent of excess energy. Our results show that nearly all charge pairs get separated by at least 7 nm in the absence of an external field and indicate that high charge mobility is crucial for charge separation.

Original language	English
Pages (from-to)	4166
Number of pages	4171
Journal	Journal of Physical Chemistry Letters
Volume	4
Issue number	23
Early online date	18 Nov 2013
DOIs	https://doi.org/10.1021/jz4020426
Publication status	Published - 5 Dec 2013

Keywords

OPV
Polaron
Separation
Depolarization
Anisotropy
Transient absorption

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This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1021/jz4020426

Matheson JPCL accepted
Copyright © 2013 American Chemical Society. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://dx.doi.org/10.1021/jz4020426
Accepted author manuscript, 936 KB

ERC Advanced Grant EXCITON: EU FP7 ERC Advanced Grant 2012 EXCITON
Samuel, I. D. W. (PI)
European Research Council
1/04/13 → 30/03/19
Project: Standard

Cite this

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title = "Charge pair dissociation and recombination dynamics in a P3HT–PC60BM bulk heterojunction",

abstract = "The mechanism by which Coulombically bound charge pairs dissociate into free carriers in photovoltaic donor–acceptor blends is of great interest. Here, we use polarization-sensitive transient absorption (TA) to study the diffusion of photogenerated holes in a polythiophene (P3HT)–fullerene (PC60BM) blend. We observe an initial anisotropy value of 0.4 for the absorption of photogenerated holes, indicating that holes generated on a 100 fs time scale are localized on the same polymer chain as their precursor excitons. Depolarization dynamics indicate fast initial hole motion on a 0.3 ps time scale and slower migration up to 100 ps. Charge pair recombination is found to occur on a much longer time scale of 10–1000 ns via a purely bimolecular process independent of excess energy. Our results show that nearly all charge pairs get separated by at least 7 nm in the absence of an external field and indicate that high charge mobility is crucial for charge separation.",

keywords = "OPV, Polaron, Separation, Depolarization, Anisotropy, Transient absorption",

author = "Matheson, {Andrew Barclay} and Pearson, {Scott James} and Arvydas Ruseckas and Samuel, {Ifor David William}",

note = "The authors thank the EPSRC, SUPA, the Condensed Matter Doctoral Training Centre and the European Union Seventh Framework programme (grant agreement 321305) for financial support.",

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T1 - Charge pair dissociation and recombination dynamics in a P3HT–PC60BM bulk heterojunction

AU - Matheson, Andrew Barclay

AU - Pearson, Scott James

AU - Ruseckas, Arvydas

AU - Samuel, Ifor David William

N1 - The authors thank the EPSRC, SUPA, the Condensed Matter Doctoral Training Centre and the European Union Seventh Framework programme (grant agreement 321305) for financial support.

PY - 2013/12/5

Y1 - 2013/12/5

N2 - The mechanism by which Coulombically bound charge pairs dissociate into free carriers in photovoltaic donor–acceptor blends is of great interest. Here, we use polarization-sensitive transient absorption (TA) to study the diffusion of photogenerated holes in a polythiophene (P3HT)–fullerene (PC60BM) blend. We observe an initial anisotropy value of 0.4 for the absorption of photogenerated holes, indicating that holes generated on a 100 fs time scale are localized on the same polymer chain as their precursor excitons. Depolarization dynamics indicate fast initial hole motion on a 0.3 ps time scale and slower migration up to 100 ps. Charge pair recombination is found to occur on a much longer time scale of 10–1000 ns via a purely bimolecular process independent of excess energy. Our results show that nearly all charge pairs get separated by at least 7 nm in the absence of an external field and indicate that high charge mobility is crucial for charge separation.

AB - The mechanism by which Coulombically bound charge pairs dissociate into free carriers in photovoltaic donor–acceptor blends is of great interest. Here, we use polarization-sensitive transient absorption (TA) to study the diffusion of photogenerated holes in a polythiophene (P3HT)–fullerene (PC60BM) blend. We observe an initial anisotropy value of 0.4 for the absorption of photogenerated holes, indicating that holes generated on a 100 fs time scale are localized on the same polymer chain as their precursor excitons. Depolarization dynamics indicate fast initial hole motion on a 0.3 ps time scale and slower migration up to 100 ps. Charge pair recombination is found to occur on a much longer time scale of 10–1000 ns via a purely bimolecular process independent of excess energy. Our results show that nearly all charge pairs get separated by at least 7 nm in the absence of an external field and indicate that high charge mobility is crucial for charge separation.

KW - OPV

KW - Polaron

KW - Separation

KW - Depolarization

KW - Anisotropy

KW - Transient absorption

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