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Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways

Ardalan Armin, Ivan Kassal, Paul E. Shaw, Mike Hambsch, Martin Stolterfoht, Dani M. Lyons, Jun Li, Zugui Shi, Paul L. Burn, Paul Meredith Orcid Logo

Journal of the American Chemical Society, Volume: 136, Issue: 32, Pages: 11465 - 11472

Swansea University Authors: Ardalan Armin, Paul Meredith Orcid Logo

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DOI (Published version): 10.1021/ja505330x

Abstract

The conventional picture of photocurrent generation in organic solar cells involves photoexcitation of the electron donor, followed by electron transfer to the acceptor via an interfacial charge-transfer state (Channel I). It has been shown that the mirror-image process of acceptor photoexcitation l...

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Published in: Journal of the American Chemical Society
ISSN: 0002-7863 1520-5126
Published: 2014
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URI: https://cronfa.swan.ac.uk/Record/cronfa39961
first_indexed 2018-05-04T13:54:22Z
last_indexed 2019-08-09T16:03:29Z
id cronfa39961
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spelling 2019-08-07T19:18:38.0775312 v2 39961 2018-05-04 Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways 22b270622d739d81e131bec7a819e2fd Ardalan Armin Ardalan Armin true false 31e8fe57fa180d418afd48c3af280c2e 0000-0002-9049-7414 Paul Meredith Paul Meredith true false 2018-05-04 The conventional picture of photocurrent generation in organic solar cells involves photoexcitation of the electron donor, followed by electron transfer to the acceptor via an interfacial charge-transfer state (Channel I). It has been shown that the mirror-image process of acceptor photoexcitation leading to hole transfer to the donor is also an efficient means to generate photocurrent (Channel II). The donor and acceptor components may have overlapping or distinct absorption characteristics. Hence, different excitation wavelengths may preferentially activate one channel or the other, or indeed both. As such, the internal quantum efficiency (IQE) of the solar cell may likewise depend on the excitation wavelength. We show that several model high-efficiency organic solar cell blends, notably PCDTBT:PC70BM and PCPDTBT:PC60/70BM, exhibit flat IQEs across the visible spectrum, suggesting that charge generation is occurring either via a dominant single channel or via both channels but with comparable efficiencies. In contrast, blends of the narrow optical gap copolymer DPP-DTT with PC70BM show two distinct spectrally flat regions in their IQEs, consistent with the two channels operating at different efficiencies. The observed energy dependence of the IQE can be successfully modeled as two parallel photodiodes, each with its own energetics and exciton dynamics but both having the same extraction efficiency. Hence, an excitation-energy dependence of the IQE in this case can be explained as the interplay between two photocurrent-generating channels, without recourse to hot excitons or other exotic processes. Journal Article Journal of the American Chemical Society 136 32 11465 11472 0002-7863 1520-5126 4 8 2014 2014-08-04 10.1021/ja505330x COLLEGE NANME COLLEGE CODE Swansea University 2019-08-07T19:18:38.0775312 2018-05-04T11:12:40.7026809 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics Ardalan Armin 1 Ivan Kassal 2 Paul E. Shaw 3 Mike Hambsch 4 Martin Stolterfoht 5 Dani M. Lyons 6 Jun Li 7 Zugui Shi 8 Paul L. Burn 9 Paul Meredith 0000-0002-9049-7414 10
title Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
spellingShingle Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
Ardalan Armin
Paul Meredith
title_short Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
title_full Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
title_fullStr Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
title_full_unstemmed Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
title_sort Spectral Dependence of the Internal Quantum Efficiency of Organic Solar Cells: Effect of Charge Generation Pathways
author_id_str_mv 22b270622d739d81e131bec7a819e2fd
31e8fe57fa180d418afd48c3af280c2e
author_id_fullname_str_mv 22b270622d739d81e131bec7a819e2fd_***_Ardalan Armin
31e8fe57fa180d418afd48c3af280c2e_***_Paul Meredith
author Ardalan Armin
Paul Meredith
author2 Ardalan Armin
Ivan Kassal
Paul E. Shaw
Mike Hambsch
Martin Stolterfoht
Dani M. Lyons
Jun Li
Zugui Shi
Paul L. Burn
Paul Meredith
format Journal article
container_title Journal of the American Chemical Society
container_volume 136
container_issue 32
container_start_page 11465
publishDate 2014
institution Swansea University
issn 0002-7863
1520-5126
doi_str_mv 10.1021/ja505330x
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 0
active_str 0
description The conventional picture of photocurrent generation in organic solar cells involves photoexcitation of the electron donor, followed by electron transfer to the acceptor via an interfacial charge-transfer state (Channel I). It has been shown that the mirror-image process of acceptor photoexcitation leading to hole transfer to the donor is also an efficient means to generate photocurrent (Channel II). The donor and acceptor components may have overlapping or distinct absorption characteristics. Hence, different excitation wavelengths may preferentially activate one channel or the other, or indeed both. As such, the internal quantum efficiency (IQE) of the solar cell may likewise depend on the excitation wavelength. We show that several model high-efficiency organic solar cell blends, notably PCDTBT:PC70BM and PCPDTBT:PC60/70BM, exhibit flat IQEs across the visible spectrum, suggesting that charge generation is occurring either via a dominant single channel or via both channels but with comparable efficiencies. In contrast, blends of the narrow optical gap copolymer DPP-DTT with PC70BM show two distinct spectrally flat regions in their IQEs, consistent with the two channels operating at different efficiencies. The observed energy dependence of the IQE can be successfully modeled as two parallel photodiodes, each with its own energetics and exciton dynamics but both having the same extraction efficiency. Hence, an excitation-energy dependence of the IQE in this case can be explained as the interplay between two photocurrent-generating channels, without recourse to hot excitons or other exotic processes.
published_date 2014-08-04T13:50:38Z
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score 11.058631

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