Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends

被引：0

作者：

Veldman, Dirk ^{[1
]}

Ipek, Özlem ^{[1
]}

Meskers, Stefan C. J. ^{[1
]}

Sweelssen, Jörgen ^{[2
,4
]}

Koetse, Marc M. ^{[2
,4
]}

Veenstra, Sjoerd C. ^{[3
,4
]}

Kroon, Jan M. ^{[3
,4
]}

Van Bavel, Svetlana S. ^{[4
,5
]}

Loos, Joachim ^{[4
,5
]}

Janssen, René A. J. ^{[1
]}

机构：

[1] Molecular Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands

[2] Holst Centre/TNO, High Tech Campus 48, 5656 AE Eindhoven, Netherlands

[3] Energy Research Centre of the Netherlands (ECN), P.O. Box 1, 1755 ZG Petten, Netherlands

[4] Dutch Polymer Institute, 5600 AX Eindhoven, Netherlands

[5] Materials and Interface Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands

来源：

Journal of the American Chemical Society | 2008年 / 130卷 / 24期

关键词：

The electro-optical properties of thin films of electron donor-acceptor blends of a fluorene copolymer (PF10TBT) and a fullerene derivative (PCBM) were studied. Transmission electron microscopy shows that in these films nanocrystalline PCBM clusters are formed at high PCBM content. For all concentrations; a charge transfer (CT) transition is observed with absorption spectroscopy; photoluminescence; and electroluminescence. The CT emission is used as a probe to investigate the dissociation of CT excited states at the donor-acceptor interface in photovoltaic devices; as a function of an applied external electric field and PCBM concentration. We find that the maximum of the CT emission shifts to lower energy and decreases in intensity with higher PCBM content. We explain the red shift of the emission and the lowering of the open-circuit voltage (VOC) of photovoltaic devices prepared from these blends with the higher relative permittivity of PCBM (Εr = 4.0) compared to that of the polymer (Εr = 3.4); stabilizing the energy (ECT) of CT states and of the free charge carriers in blends with higher PCBM concentration. We show that the CT state has a short decay time (τ = ca. 4 ns) that is reduced by the application of an external electric field or with increasing PCBM content. The field-induced quenching can be explained quantitatively with the Onsager-Braun model for the dissociation of the CT states when including a high electron mobility in nanocrystalline PCBM clusters. Furthermore; photoinduced absorption spectroscopy shows that increasing the PCBM concentration reduces the yield of neutral triplet excitons forming via electron-hole recombination; and increases the lifetime of radical cations. The presence of nanocrystalline domains with high local carrier mobility of at least one of the two components in an organic heterojunction may explain efficient dissociation of CT states into free charge carriers. © 2008 American Chemical Society;

D O I：

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学科分类号：

摘要：

Journal article (JA)

引用

页码：7721 / 7735

共 28 条

[1] Compositional and electric field dependence of the dissociation of charge transfer excitons in alternating polyfluorene copolymer/fullerene blends
Veldman, Dirk
Ipek, Oezlem
Meskers, Stefan C. J.
Sweelssen, Joergen
Koetse, Marc M.
Veenstra, Sjoerd C.
Kroon, Jan M.
van Bavel, Svetlana S.
Loos, Joachim
Janssen, Rene A. J.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2008, 130 (24) : 7721 - 7735
[2] Geminate charge recombination in alternating polyfluorene copolymer/fullerene blends
De, Swati
Pascher, Torbjörn
Maiti, Manisankar
Jespersen, Kim G.
Kesti, Tero
Zhang, Fengling
Inganäs, Olle
Yartsev, Arkady
Sundström, Villy
Journal of the American Chemical Society, 2007, 129 (27): : 8466 - 8472
[3] Geminate charge recombination in alternating polyfluorene Copolymer/Fullerene blends
De, Swati
Pascher, Torbjorn
Maiti, Manisankar
Jespersen, Kim G.
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Inganas, Olle
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JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2007, 129 (27) : 8466 - 8472
[4] Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative
Loi, Maria Antonietta
Toffanin, Stefano
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ADVANCED FUNCTIONAL MATERIALS, 2007, 17 (13) : 2111 - 2116
[5] Charge carrier dynamics in alternating polyfluorene copolymer:: Fullerene blends probed by terahertz spectroscopy
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JOURNAL OF PHYSICAL CHEMISTRY C, 2008, 112 (16): : 6558 - 6563
[6] CHARGE TRANSFER EXCITONS IN CONJUGATED POLYMER/FULLERENE BLENDS
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Da Como, Enrico
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Haneder, Stephan
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11TH INTERNATIONAL CONFERENCE ON OPTICS OF EXCITONS IN CONFINED SYSTEMS (OECS11), 2010, 210
[7] Subnanosecond charge photogeneration and recombination in polyfluorene copolymer-fullerene solar cell: Effects of electric field
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OPTICS EXPRESS, 2013, 21 (05): : A241 - A249
[8] THE INFLUENCE OF DRIVING FORCE ON FORMATION AND GEMINATE RECOMBINATION OF CHARGES IN ALTERNATING POLYFLUORENE COPOLYMER/FULLERENE BLENDS
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[9] Enhanced dissociation of excitons and charge transfer in organic solar cells of polymer: Fullerene blends with molecular BPFZn doping
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INTERNATIONAL JOURNAL OF ENERGY RESEARCH, 2022, 46 (07) : 8716 - 8725
[10] Charge Transfer Excitons in Polymer/Fullerene Blends: The Role of Morphology and Polymer Chain Conformation
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