Efficient Long - Range Electron Transfer Processes in Polyfluorene – Perylene Diimide Blends

Anna Isakova, Safakath Karuthedath, Thomas Arnold, Jonathan Howse, Paul D. Topham, Daniel Thomas William Toolan, Frédéric Laquai, Larry Lüer

Research output: Contribution to journalArticle

Abstract

In bulk heterojunction donor-acceptor (D-A) blends, high photovoltaic yields require charge carrier separation to outcompete geminate recombination. Recently, evidence for long-range electron transfer mechanisms has been presented, avoiding strongly-bound interfacial charge transfer (CT) states. However, due to the lack of specific optical probes at the D-A interface, a detailed quantification of the long-range processes has not been feasible, until now. Here, we present a transient absorption study of long-range processes in a unique phase consisting of perylene diimide (PDI) crystals intercalated with polyfluorene (PFO), as widely used non-fullerene electron acceptor and donor, respectively. The intercalated PDI:PFO phase possesses specific well-separated spectral features for the excited states at the D-A interface. By use of femtosecond spectroscopy we reveal the excitation dynamics in this blend. PDI excitons undergo a clear symmetry-breaking charge separation in the PDI bulk, which occurs within several hundred femtoseconds, thus outcompeting excimer formation, known to limit charge separation yields when PDI is used as an acceptor. In contrast, PFO excitons are dissociated with very high yields in a one-step long-range process, enabled by large delocalization of the PFO exciton wavefunction. Moreover, both scenarios circumvent the formation of strongly-bound interfacial CT states and enable a targeted interfacial design for bulk heterojunction blends with near unity charge separation yields.
LanguageEnglish
Pages10934-10944
JournalNanoscale
Volume10
Early online date17 May 2018
DOIs
Publication statusE-pub ahead of print - 17 May 2018

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Perylene
Excitons
Electrons
Heterojunctions
Charge transfer
Crystal symmetry
Wave functions
Charge carriers
Excited states
Spectroscopy
Crystals
LDS 751

Bibliographical note

© The Royal Society of Chemistry 2018

Cite this

Isakova, A., Karuthedath, S., Arnold, T., Howse, J., Topham, P. D., Toolan, D. T. W., ... Lüer, L. (2018). Efficient Long - Range Electron Transfer Processes in Polyfluorene – Perylene Diimide Blends. Nanoscale, 10, 10934-10944. https://doi.org/10.1039/C8NR01064A
Isakova, Anna ; Karuthedath, Safakath ; Arnold, Thomas ; Howse, Jonathan ; Topham, Paul D. ; Toolan, Daniel Thomas William ; Laquai, Frédéric ; Lüer, Larry. / Efficient Long - Range Electron Transfer Processes in Polyfluorene – Perylene Diimide Blends. In: Nanoscale. 2018 ; Vol. 10. pp. 10934-10944.
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Isakova, A, Karuthedath, S, Arnold, T, Howse, J, Topham, PD, Toolan, DTW, Laquai, F & Lüer, L 2018, 'Efficient Long - Range Electron Transfer Processes in Polyfluorene – Perylene Diimide Blends' Nanoscale, vol. 10, pp. 10934-10944. https://doi.org/10.1039/C8NR01064A

Efficient Long - Range Electron Transfer Processes in Polyfluorene – Perylene Diimide Blends. / Isakova, Anna; Karuthedath, Safakath; Arnold, Thomas; Howse, Jonathan; Topham, Paul D.; Toolan, Daniel Thomas William; Laquai, Frédéric; Lüer, Larry.

In: Nanoscale, Vol. 10, 17.05.2018, p. 10934-10944.

Research output: Contribution to journalArticle

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AU - Isakova, Anna

AU - Karuthedath, Safakath

AU - Arnold, Thomas

AU - Howse, Jonathan

AU - Topham, Paul D.

AU - Toolan, Daniel Thomas William

AU - Laquai, Frédéric

AU - Lüer, Larry

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