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Ohta K, Tominaga K, Ikoma T, Kobori Y, Yamada H. Microscopic Structures, Dynamics, and Spin Configuration of the Charge Carriers in Organic Photovoltaic Solar Cells Studied by Advanced Time-Resolved Spectroscopic Methods. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:7365-7382. [PMID: 35675205 DOI: 10.1021/acs.langmuir.2c00290] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Organic photovoltaics (OPVs) are promising solutions for renewable energy and sustainable technologies and have attracted much attention in recent years. Two types of organic semiconductors are used as donor materials to fabricate OPV cells. One type is a photoconductive polymer, and the other type is a small-molecule-based compound. The discovery of a bulk-heterojunction (BHJ) structure using a mixture of p- and n-type organic semiconductors has dramatically increased the power conversion efficiency (PCE) of OPV cells. In this feature article, we review our recent studies on organic BHJ thin films and OPVs by using advanced time-resolved spectroscopic techniques. Two topics regarding the microscopic behaviors of the charge carriers are discussed. The first topic is focused on how to quantify the local mobility of the charge carriers. Here, we discuss charge carrier dynamics in diketopyrrolopyrrole-linked tetrabenzoporphyrin (DPP-BP) BHJ thin films studied by time-resolved terahertz spectroscopy on a subpicosecond to several tens of picoseconds time scale and by transient photocurrent measurements on a microsecond time scale. The second topic concerns the spin configuration and interaction of the electron and hole of the polaron pairs in polymer-based BHJ thin films and OPV cells studied by the time-resolved electron paramagnetic resonance method, time-resolved simultaneous optical and electrical detection, and measurement of the magnetoconductance effect.
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Affiliation(s)
- Kaoru Ohta
- Molecular Photoscience Research Center, Kobe University, Rokkodai-cho 1-1, Nada, Kobe, 657-8501, Japan
| | - Keisuke Tominaga
- Molecular Photoscience Research Center, Kobe University, Rokkodai-cho 1-1, Nada, Kobe, 657-8501, Japan
| | - Tadaaki Ikoma
- Graduate School of Science and Technology, Niigata University, 2-8050, Ikarashi, Nishi-ku, Niigata950-2181, Japan
| | - Yasuhiro Kobori
- Molecular Photoscience Research Center, Kobe University, Rokkodai-cho 1-1, Nada, Kobe, 657-8501, Japan
| | - Hiroko Yamada
- Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5, Takayama-cho, Ikoma, Nara630-0192, Japan
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2
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Steyrleuthner R, Zhang Y, Zhang L, Kraffert F, Cherniawski BP, Bittl R, Briseno AL, Bredas JL, Behrends J. Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer. Phys Chem Chem Phys 2018; 19:3627-3639. [PMID: 28094360 DOI: 10.1039/c6cp07485e] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigate the delocalization of holes in the semicrystalline conjugated polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) by directly measuring the hyperfine coupling between photogenerated polarons and bound nuclear spins using electron nuclear double resonance spectroscopy. An extrapolation of the corresponding oligomer spectra reveals that charges tend to delocalize over 4.0-4.8 nm with delocalization strongly dependent on molecular order and crystallinity of the PBTTT polymer thin films. Density functional theory calculations of hyperfine couplings confirm that long-range corrected functionals appropriately describe the change in coupling strength with increasing oligomer size and agree well with the experimentally measured polymer limit. Our discussion presents general guidelines illustrating the various pitfalls and opportunities when deducing polaron localization lengths from hyperfine coupling spectra of conjugated polymers.
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Affiliation(s)
- Robert Steyrleuthner
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
| | - Yuexing Zhang
- King Abdullah University of Science & Technology, Solar & Photovoltaics Engineering Research Center, Thuwal 23955-6900, Saudi Arabia and Department of Chemistry, Hubei University, Wuhan 430062, China
| | - Lei Zhang
- Department of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA
| | - Felix Kraffert
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
| | - Benjamin P Cherniawski
- Department of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA
| | - Robert Bittl
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
| | - Alejandro L Briseno
- Department of Polymer Science and Engineering, Conte Research Center, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003, USA
| | - Jean-Luc Bredas
- King Abdullah University of Science & Technology, Solar & Photovoltaics Engineering Research Center, Thuwal 23955-6900, Saudi Arabia
| | - Jan Behrends
- Freie Universität Berlin, Berlin Joint EPR Lab, Institut für Experimentalphysik, Berlin, Germany.
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Miura T, Tao R, Shibata S, Umeyama T, Tachikawa T, Imahori H, Kobori Y. Geometries, Electronic Couplings, and Hole Dissociation Dynamics of Photoinduced Electron–Hole Pairs in Polyhexylthiophene–Fullerene Dyads Rigidly Linked by Oligophenylenes. J Am Chem Soc 2016; 138:5879-85. [DOI: 10.1021/jacs.5b13414] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Taku Miura
- Department
of Chemistry, Graduate School of Science, Kobe University, 1-1
Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
| | - Ran Tao
- Department
of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Sho Shibata
- Department
of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Tomokazu Umeyama
- Department
of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Takashi Tachikawa
- Department
of Chemistry, Graduate School of Science, Kobe University, 1-1
Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
| | - Hiroshi Imahori
- Department
of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
- Institute
for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Yasuhiro Kobori
- Department
of Chemistry, Graduate School of Science, Kobe University, 1-1
Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
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Structural and electronic properties of doped oligothiophenes in the presence of p-toluenesulfonate acids. Theor Chem Acc 2015. [DOI: 10.1007/s00214-015-1663-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Takeda N, Miller JR. Poly(3-decylthiophene) radical anions and cations in solution: single and multiple polarons and their delocalization lengths in conjugated polymers. J Phys Chem B 2012; 116:14715-23. [PMID: 23157495 DOI: 10.1021/jp3096242] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Optical absorption spectra of anions and cations of poly(3-decylthiophene) (P3DT) in solution were identified as single polarons. Pulse radiolysis of P3DT in THF determined the spatial extent of one negative polaron to be ~11.5 thiophene units by observing transient absorption of P3DT(-•) radical ions, which are prinicpally free ions, at 850 nm with ε = (7.25 ± 0.47) × 10(4) M(-1) cm(-1) and bleaching of the neutral absorption band at 450 nm. P3DT(-•) was formed in a combination of diffusive reactions and fast "step" processes. Similarly, a positive polaron of P3DT was estimated to delocalize over ~8.7 thiophene units by pulse radiolysis in chloroform. Chemical reduction by sodium and oxidation by FeCl(3) injected multiple charges into a single P3DT chain while showing absorption spectra in the early stages of reaction resembling those observed by pulse radiolysis. The results indicated that multiple polarons exist in a single chain of P3DT before coalescing into bipolarons or transforming into other forms of polaron.
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Affiliation(s)
- Norihiko Takeda
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
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Savenije TJ, Sperlich A, Kraus H, Poluektov O, Heeney M, Dyakonov V. Observation of bi-polarons in blends of conjugated copolymers and fullerene derivatives. Phys Chem Chem Phys 2011; 13:16579-84. [DOI: 10.1039/c1cp21607d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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7
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Hasjim PL, Ponomarenko N, Weber S, Norris JR. Exploring Electron Spin−Spin Interactions of Paramagnetic Iron and Radical Cations of Bacteriochlorophyll from Oxidized LH1 in the Presence of Electron Transfer in the Frozen State. J Phys Chem B 2010; 114:14194-9. [PMID: 20151665 DOI: 10.1021/jp908572m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Petersen L. Hasjim
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, Department of Physics, Free University of Berlin, 14195 Berlin, Germany, and Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637
| | - Nina Ponomarenko
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, Department of Physics, Free University of Berlin, 14195 Berlin, Germany, and Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637
| | - Stefan Weber
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, Department of Physics, Free University of Berlin, 14195 Berlin, Germany, and Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637
| | - James R. Norris
- Department of Chemistry, University of Chicago, Chicago, Illinois 60637, Department of Physics, Free University of Berlin, 14195 Berlin, Germany, and Institute of Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637
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Aguirre A, Gast P, Orlinskii S, Akimoto I, Groenen EJJ, El Mkami H, Goovaerts E, Van Doorslaer S. Multifrequency EPR analysis of the positive polaron in I2-doped poly(3-hexylthiophene) and in poly[2-methoxy-5-(3,7-dimethyloctyloxy)]-1,4-phenylenevinylene. Phys Chem Chem Phys 2008; 10:7129-38. [DOI: 10.1039/b811419f] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Kuroda SI, Marumoto K, Sakanaka T, Takeuchi N, Shimoi Y, Abe S, Kokubo H, Yamamoto T. Electron-nuclear double-resonance observation of spatial extent of polarons in polythiophene and poly(3-alkylthiophene). Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2006.12.101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Marumoto K, Kuroda SI, Takenobu T, Iwasa Y. Spatial extent of wave functions of gate-induced hole carriers in pentacene field-effect devices as investigated by electron spin resonance. PHYSICAL REVIEW LETTERS 2006; 97:256603. [PMID: 17280376 DOI: 10.1103/physrevlett.97.256603] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Indexed: 05/13/2023]
Abstract
An electron spin resonance (ESR) method is applied to a pentacene field-effect device to investigate gate-induced hole carriers in such devices. Clear field-induced ESR signals are observed, demonstrating that all of the field-injected carriers have S = 1/2 spins. Anisotropic ESR signals due to unpaired pi electrons show the molecular orientation at the interface in the devices. The spatial extent of the spin density distribution (wave function) of the carriers is evaluated from the ESR linewidth, accounting for the hyperfine structure, to be of the order of 10 molecules.
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Affiliation(s)
- Kazuhiro Marumoto
- Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan.
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Marumoto K, Nagano Y, Sakamoto T, Ukai S, Ito H, Kuroda S. ESR studies of field-induced polarons in MIS diode structures with self-organized regioregular poly(3-hexylthiophene). Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.09.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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12
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Kuroda SI. J-aggregation and its characterization in Langmuir-Blodgett films of merocyanine dyes. Adv Colloid Interface Sci 2004; 111:181-209. [PMID: 15589808 DOI: 10.1016/j.cis.2004.09.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2003] [Accepted: 09/03/2004] [Indexed: 11/30/2022]
Abstract
Langmuir-Blodgett (LB) films are constructed by successively transferring monomolecular layers formed at the air-water interface onto solid substrates. One of the advantages of the LB technique in fabricating molecular aggregates lies in the fact that it can employ various kinds of molecules by mixing them at the air-water interface. The mixed system may exhibit new properties that are not observed for individual components. This method would be useful, for example, in the studies of the formation and control of the J-aggregates of functional dyes that attract attention both in science and technology. In this paper, I review this subject mainly based on our recent results in merocyanines. LB films of merocyanine dyes, mixed with arachidic acid (C(20)), exhibit J-aggregate formation and have been serving as typical systems in revealing the physical and structural aspects of nanosized molecular aggregates constructed as monolayers. In the case of LB films of a merocyanine dye having benzothiazole as donor nucleus (abbreviated as DS), electron spin resonance (ESR) spectroscopy has been successful in determining the characteristic in-plane orientation of dye molecules with respect to the dipping direction, which led to the discovery of the flow orientation effect during the dipping process of LB films as the origin of optical dichroism often observed in LB films. In this article, after an introduction of ESR spectroscopy, three major topics on the merocyanine J-aggregation and its characterization in mixed films are discussed. The first topic is the observation and control of the size of J-aggregates in the dilution limit of dyes in arachidic acid matrix for a methyl-substituted DS (6-Me-DS). Dependence of atomic force microscopy (AFM) patterns on the molar ratio allows the identification of dye domains. J-band optical peak analysis based on the Kuhn's extended dipole model, supplemented by a novel application of femtosecond pump-probe optical spectroscopy, yields the size of the J-aggregates of 10(3). The second topic is the control of the J-band peak wavelengths by mixing two different kinds of dye molecules. The first case is the mixture of a J-forming 6-Me-DS and non-J-forming merocyanine analog, DO with benzo-oxazole instead of benzothiazole of DS. The second case is the mixture of both J-forming dyes but with different J-band peak positions, 6-Me-DS and another analog of 5-Cl-DS. The optical peak shifts depending on the molar mixing ratio will be presented. The last topic is related to the elucidation of electronic states of dye molecules in the J-aggregates. Light-induced ESR (LESR) of DS films with stable isotope ((15)N or (13)C)-substituted dyes provide clear evidence for the photoinduced charge transfer by the detection of hyperfine structures. Moreover, infrared (IR) spectroscopy of (13)C-enriched dye identifies the IR absorption peak of the relevant carbon in the chromophore. The results give evidence for the enhanced intramolecular charge transfer of dyes in the J-aggregates compared with an isolated merocyanine composed of donor and acceptor moiety. Lastly, the Cl attachment in 5-Cl-DS leads to a significant enhancement of the nitrogen hyperfine coupling in the LESR spectra. These examples and others demonstrate the potential of LB films of merocyanines in the studies of the nanosized molecular aggregates in monolayer assemblies.
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Affiliation(s)
- Shin-ichi Kuroda
- Department of Applied Physics, Nagoya University, Nagoya 464-8603, Japan.
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