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Nanayakkara MPA, He Q, Ruseckas A, Karalasingam A, Matjacic L, Masteghin MG, Basiricò L, Fratelli I, Ciavatti A, Kilbride RC, Jenatsch S, Parnell AJ, Fraboni B, Nisbet A, Heeney M, Jayawardena KDGI, Silva SRP. Tissue Equivalent Curved Organic X-ray Detectors Utilizing High Atomic Number Polythiophene Analogues. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304261. [PMID: 37916896 PMCID: PMC10724441 DOI: 10.1002/advs.202304261] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 09/29/2023] [Indexed: 11/03/2023]
Abstract
Organic semiconductors are a promising material candidate for X-ray detection. However, the low atomic number (Z) of organic semiconductors leads to poor X-ray absorption thus restricting their performance. Herein, the authors propose a new strategy for achieving high-sensitivity performance for X-ray detectors based on organic semiconductors modified with high -Z heteroatoms. X-ray detectors are fabricated with p-type organic semiconductors containing selenium heteroatoms (poly(3-hexyl)selenophene (P3HSe)) in blends with an n-type fullerene derivative ([6,6]-Phenyl C71 butyric acid methyl ester (PC70 BM). When characterized under 70, 100, 150, and 220 kVp X-ray radiation, these heteroatom-containing detectors displayed a superior performance in terms of sensitivity up to 600 ± 11 nC Gy-1 cm-2 with respect to the bismuth oxide (Bi2 O3 ) nanoparticle (NP) sensitized organic detectors. Despite the lower Z of selenium compared to the NPs typically used, the authors identify a more efficient generation of electron-hole pairs, better charge transfer, and charge transport characteristics in heteroatom-incorporated detectors that result in this breakthrough detector performance. The authors also demonstrate flexible X-ray detectors that can be curved to a radius as low as 2 mm with low deviation in X-ray response under 100 repeated bending cycles while maintaining an industry-standard ultra-low dark current of 0.03 ± 0.01 pA mm-2 .
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Affiliation(s)
- M. Prabodhi A. Nanayakkara
- Advanced Technology Institute, Department of Electrical and Electronic EngineeringUniversity of SurreyGuildfordSurreyGU2 7XHUK
| | - Qiao He
- Department of Chemistry and Centre for Processable ElectronicsImperial College London, White City CampusLondonW12 0BZUK
| | - Arvydas Ruseckas
- School of Physics & AstronomyUniversity of St AndrewsPhysical Science Building, North HaughSt AndrewsUK
| | | | | | - Mateus G. Masteghin
- Advanced Technology Institute, Department of Electrical and Electronic EngineeringUniversity of SurreyGuildfordSurreyGU2 7XHUK
| | - Laura Basiricò
- Department of Physics and AstronomyUniversity of BolognaViale Berti Pichat 6/2Bologna40127Italy
- National Institute for Nuclear PhysicsINFN Section of BolognaBolognaItaly
| | - Ilaria Fratelli
- Department of Physics and AstronomyUniversity of BolognaViale Berti Pichat 6/2Bologna40127Italy
- National Institute for Nuclear PhysicsINFN Section of BolognaBolognaItaly
| | - Andrea Ciavatti
- Department of Physics and AstronomyUniversity of BolognaViale Berti Pichat 6/2Bologna40127Italy
- National Institute for Nuclear PhysicsINFN Section of BolognaBolognaItaly
| | - Rachel C. Kilbride
- Department of ChemistryUniversity of SheffieldDainton BuildingSheffieldS3 7HFUK
| | | | - Andrew J. Parnell
- Department of Physics and AstronomyUniversity of SheffieldHicks BuildingSheffieldS3 7RHUK
| | - Beatrice Fraboni
- Department of Physics and AstronomyUniversity of BolognaViale Berti Pichat 6/2Bologna40127Italy
- National Institute for Nuclear PhysicsINFN Section of BolognaBolognaItaly
| | - Andrew Nisbet
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonGower St, BloomsburyLondonWC1E 6BTUK
| | - Martin Heeney
- Department of Chemistry and Centre for Processable ElectronicsImperial College London, White City CampusLondonW12 0BZUK
| | - K. D. G. Imalka Jayawardena
- Advanced Technology Institute, Department of Electrical and Electronic EngineeringUniversity of SurreyGuildfordSurreyGU2 7XHUK
| | - S. Ravi P. Silva
- Advanced Technology Institute, Department of Electrical and Electronic EngineeringUniversity of SurreyGuildfordSurreyGU2 7XHUK
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2
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Roy P, Anandan GT, Nayak N, Kumar A, Dasgupta J. Raman Snapshots of Side-Chain Dependent Polaron Dynamics in PolyThiophene Films. J Phys Chem B 2023; 127:567-576. [PMID: 36599044 DOI: 10.1021/acs.jpcb.2c06185] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Photogenerated polarons in π-conjugated polymers are the precursors to free charges at donor-acceptor interfaces. Unraveling the relationship between film morphology and polaron formation is conjectured to enable efficient charge generation in organic photovoltaic devices. However, it has been challenging to track the ultrafast dynamics of polarons selectively and thus evaluate the molecular coordinates that drive charge generation in films. Using a combination of broadband femtosecond transient absorption and resonance-selective femtosecond stimulated Raman spectroscopy, here, we investigate the polaron generation dynamics exclusively in traditional crystalline poly(3-hexylthiophene) (P3HT) and its amorphous side-chain variant poly(3-(2-ethylhexyl)thiophene-2,5-diyl) (P3EHT) films. The transient Raman data unequivocally provides evidence for an initial delocalization of the polaronic states via thiophene backbone planarization in ∼100 fs while capturing the subsequent morphology-dependent cooling dynamics in a few picoseconds. Our work highlights the structural significance of crystalline morphology in generating hot-charges and thereby emphasizes the importance of side-chain engineering in designing highly efficient conjugated polymer films for hot-carrier photovoltaic devices.
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Affiliation(s)
- Palas Roy
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| | - Gokul T Anandan
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
| | - Nagaraj Nayak
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Anil Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Jyotishman Dasgupta
- Department of Chemical Sciences, Tata Institute of Fundamental Research, 1 Homi Bhabha Road, Mumbai 400005, India
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3
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Patterson CH, Sahoo SR. Charge Transfer Excitons in π -stacked Thiophene Oligomers and P3[Alkyl]T Crystals: CIS calculations and electroabsorption spectroscopy. J Chem Phys 2022; 157:074901. [DOI: 10.1063/5.0098575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Poly(3-alkylthiophenes), P3[Alkyl]T, exhibit high mobility and efficiency of formation of polaronic chargecarriers generated by light absorption which gives them applications in field effect devices. Excited states ofπ -stacked dimers of tetra-thiophene oligomers (T4), infinite isolated polythiophene (PT) chains and P3[Alkyl]Tcrystals are modeled using configuration interaction singles (CIS) calculations. Excited states in cofacial T4dimers are mostly localized, Frenkel (FR) states except for two low energy CT exciton states which become theionization potential and electron affinity levels of T4 molecules at large dimer separation. The lowest excitedstates in infinite, isolated PT chains and P3[Alkyl]T crystals are intra-chain excitons where the electron and holeare localized on the same chain. The next lowest excited states are inter-chain, CT excitons in which electronand hole reside on neighboring chains. The former capture almost all optical oscillator strength and the lattermay be a route to efficient formation of polaronic charge carriers in P3[Alkyl]T systems. Changes in opticalabsorption energies of T4 dimers are explained as a function of molecular separation using CIS calculations withfour frontier orbitals in the active space. Shifts in optical absorption energy observed on going from isolatedchains to P3[Alkyl]T lamellar structures are already present in single-particle transition energies induced bydirect π - π interactions at short range. The electroabsorption spectrum of T4 dimers is calculated as a functionof dimer separation and states which are responsible for parallel and perpendicular components of the spectrumare identified.
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Naqvi S, Vasistha N, Kumar M, Kumar R. Electron transport and ultrafast spectroscopic studies of new methanofullerenes bearing a heteroatom in the exohedral chain. NEW J CHEM 2019. [DOI: 10.1039/c9nj04188e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Heteroatom-bearing methanofullerenes with exciting photophysical and electron transport properties are shown to be an addition to the variety of fullerene derivatives for use as n-type materials in organic electronics.
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Affiliation(s)
- Samya Naqvi
- Advanced Materials and Devices Metrology Division
- Photovoltaic Metrology Group
- CSIR-National Physical Laboratory
- Dr. K. S. Krishnan Marg
- India
| | - Nikita Vasistha
- Academy of Scientific and Innovative Research
- India
- Advanced Materials and Devices Metrology Division
- Photonics Materials Metrology Group
- CSIR-National Physical Laboratory
| | - Mahesh Kumar
- Academy of Scientific and Innovative Research
- India
- Advanced Materials and Devices Metrology Division
- Photonics Materials Metrology Group
- CSIR-National Physical Laboratory
| | - Rachana Kumar
- Advanced Materials and Devices Metrology Division
- Photovoltaic Metrology Group
- CSIR-National Physical Laboratory
- Dr. K. S. Krishnan Marg
- India
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5
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Rana D, Donfack P, Jovanov V, Wagner V, Materny A. Ultrafast polaron-pair dynamics in a poly(3-hexylthiophene-2,5-diyl) device influenced by a static electric field: insights into electric-field-related charge loss. Phys Chem Chem Phys 2019; 21:21236-21248. [DOI: 10.1039/c9cp03736e] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Photogenerated polaron-pair ultrafast dynamics in poly(3-hexylthiophene)-based devices are found to be influenced by external electric fields via delayed field-induced singlet exciton dissociation, yielding a bimolecular decay contribution.
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Affiliation(s)
- Debkumar Rana
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Patrice Donfack
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Vladislav Jovanov
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Veit Wagner
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
| | - Arnulf Materny
- Physics and Earth Sciences, Jacobs University Bremen
- 28759 Bremen
- Germany
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6
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Inganäs O. Organic Photovoltaics over Three Decades. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1800388. [PMID: 29938847 DOI: 10.1002/adma.201800388] [Citation(s) in RCA: 235] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/20/2018] [Indexed: 05/20/2023]
Abstract
The development of organic semiconductors for photovoltaic devices, over the last three decades, has led to unexpected performance for an alternative choice of materials to convert sunlight to electricity. New materials and developed concepts have improved the photovoltage in organic photovoltaic devices, where records are now found above 13% power conversion efficiency in sunlight. The author has stayed with the topic of organic materials for energy conversion and energy storage during these three decades, and makes use of the Hall of Fame now built by Advanced Materials, to present his view of the path travelled over this time, including motivations, personalities, and ambitions.
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Affiliation(s)
- Olle Inganäs
- Biomolecular and Organic Electronics, Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83, Linköping, Sweden
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7
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Abstract
![]()
The field of organic
photovoltaics has developed rapidly over the
last 2 decades, and small solar cells with power conversion efficiencies
of 13% have been demonstrated. Light absorbed in the organic layers
forms tightly bound excitons that are split into free electrons and
holes using heterojunctions of electron donor and acceptor materials,
which are then extracted at electrodes to give useful electrical power.
This review gives a concise description of the fundamental processes
in photovoltaic devices, with the main emphasis on the characterization
of energy transfer and its role in dictating device architecture,
including multilayer planar heterojunctions, and on the factors that
impact free carrier generation from dissociated excitons. We briefly
discuss harvesting of triplet excitons, which now attracts substantial
interest when used in conjunction with singlet fission. Finally, we
introduce the techniques used by researchers for characterization
and engineering of bulk heterojunctions to realize large photocurrents,
and examine the formed morphology in three prototypical blends.
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Affiliation(s)
- Gordon J Hedley
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews , North Haugh, St Andrews, Fife KY16 9SS, U.K
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8
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Hu Z, Willard AP, Ono RJ, Bielawski CW, Rossky PJ, Vanden Bout DA. An insight into non-emissive excited states in conjugated polymers. Nat Commun 2015; 6:8246. [PMID: 26391514 PMCID: PMC4595598 DOI: 10.1038/ncomms9246] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 08/03/2015] [Indexed: 11/25/2022] Open
Abstract
Conjugated polymers in the solid state usually exhibit low fluorescence quantum yields, which limit their applications in many areas such as light-emitting diodes. Despite considerable research efforts, the underlying mechanism still remains controversial and elusive. Here, the nature and properties of excited states in the archetypal polythiophene are investigated via aggregates suspended in solvents with different dielectric constants (ɛ). In relatively polar solvents (ɛ>∼ 3), the aggregates exhibit a low fluorescence quantum yield (QY) of 2–5%, similar to bulk films, however, in relatively nonpolar solvents (ɛ<∼ 3) they demonstrate much higher fluorescence QY up to 20–30%. A series of mixed quantum-classical atomistic simulations illustrate that dielectric induced stabilization of nonradiative charge-transfer (CT) type states can lead to similar drastic reduction in fluorescence QY as seen experimentally. Fluorescence lifetime measurement reveals that the CT-type states exist as a competitive channel of the formation of emissive exciton-type states. Conjugated polymers in thin films exhibit low fluorescence quantum yields, but the mechanism is still unclear. Here, Hu et al. show the trade-off between charge transfer and emissive exciton states, whilst the former can be suppressed via dielectric-induced stabilization for large fluorescence quantum yields.
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Affiliation(s)
- Zhongjian Hu
- Center for Nano- and Molecular Science and Technology, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Adam P Willard
- Center for Nano- and Molecular Science and Technology, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Robert J Ono
- Center for Nano- and Molecular Science and Technology, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Christopher W Bielawski
- Center for Nano- and Molecular Science and Technology, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - Peter J Rossky
- Center for Nano- and Molecular Science and Technology, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
| | - David A Vanden Bout
- Center for Nano- and Molecular Science and Technology, Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, USA
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9
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Ward AJ, Ruseckas A, Kareem MM, Ebenhoch B, Serrano LA, Al-Eid M, Fitzpatrick B, Rotello VM, Cooke G, Samuel IDW. The impact of driving force on electron transfer rates in photovoltaic donor-acceptor blends. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:2496-2500. [PMID: 25759321 DOI: 10.1002/adma.201405623] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/24/2015] [Indexed: 06/04/2023]
Abstract
The effect of acceptor energy level on electron transfer rate in blends of the polymer solar-cell material poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) is studied using time-resolved fluorescence. Fast electron transfer in less than 2 ps is observed for a driving force between 0.2 and 0.6 eV and the electron transfer is slower outside this range. This dependence is described by Marcus theory with a reorganization energy of ≈0.4 eV.
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Affiliation(s)
- Alexander J Ward
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, KY16 9SS, UK
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10
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Thomas AK, Garcia JA, Ulibarri-Sanchez J, Gao J, Grey JK. High intrachain order promotes triplet formation from recombination of long-lived polarons in poly(3-hexylthiophene) J-aggregate nanofibers. ACS NANO 2014; 8:10559-68. [PMID: 25285851 DOI: 10.1021/nn5040026] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Photoluminescence (PL) of single poly(3-hexylthiophene) (P3HT) J-aggregate nanofibers (NFs) exhibits strong quenching under intensity-modulated pulsed excitation. Initial PL intensities (I(0)) decay to steady-state levels (ISS) typically within ∼ 1-10 μs, and large quenching depths (I(0)/I(SS) >2) are observed for ∼ 70% of these NFs. Similar studies of polymorphic, H-aggregate type P3HT NFs show much smaller PL quenching depths (I(0)/I(SS) ≤ 1.2). P3HT chains in J-type NF π-stacks possess high intrachain order, which has been shown previously to promote the formation of long-lived, delocalized polarons. We propose that these species recombine nongeminately to triplets on time scales of >1 ns. The identity of triplets as the dominant PL quenchers was confirmed by subjecting NFs to oxygen, resulting in an instantaneous loss of triplet PL quenching (I(0)/I(SS) ∼ 1). The lower intrachain order in H-type NFs, similar to P3HT thin-film aggregates, localizes excitons and polarons, leading to efficient geminate recombination that suppresses triplet formation at longer time scales. Our results demonstrate the promise of self-assembly strategies to control intrachain ordering within multichromophoric polymeric aggregate assemblies to tune exciton coupling and interconversion processes between different spin states.
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Affiliation(s)
- Alan K Thomas
- Department of Chemistry and Chemical Biology, University of New Mexico , MSC03 2060, Albuquerque, New Mexico 87131, United States
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11
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Cooke DG, Krebs FC, Jepsen PU. Direct observation of sub-100 fs mobile charge generation in a polymer-fullerene film. PHYSICAL REVIEW LETTERS 2012; 108:056603. [PMID: 22400948 DOI: 10.1103/physrevlett.108.056603] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Indexed: 05/31/2023]
Abstract
The formation of mobile charges in a roll-to-roll processed poly-3-hexylthiophene-fullerene bulk heterojunction film is observed directly by using transient terahertz spectroscopy with sub-100 fs temporal resolution. The transient terahertz ac conductivity reveals that 20% of the incident pump photons are converted into highly delocalized charges within the 40 fs, 3.1 eV pump pulse duration, which then rapidly becomes localized within 120 fs. Approximately 2/3 of these carriers subsequently decay, possibly into an exciton, on a 1 ps time scale.
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Affiliation(s)
- D G Cooke
- Department of Physics, McGill University, Montreal, Canada H3A 2T8
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12
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Junior LAR, Neto PHO, da Cunha WF, Silva GME. Dynamics of Photogenerated Polaron-Excitons in Organic Semiconductors. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.phpro.2012.03.681] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Cabanillas-Gonzalez J, Grancini G, Lanzani G. Pump-probe spectroscopy in organic semiconductors: monitoring fundamental processes of relevance in optoelectronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:5468-5485. [PMID: 22020959 DOI: 10.1002/adma.201102015] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Indexed: 05/31/2023]
Abstract
In this review we highlight the contribution of pump-probe spectroscopy to understand elementary processes taking place in organic based optoelectronic devices. The techniques described in this article span from conventional pump-probe spectroscopy to electromodulated pump-probe and the state-of-the-art confocal pump-probe microscopy. The article is structured according to three fundamental processes (optical gain, charge photogeneration and charge transport) and the contribution of these techniques on them. The combination of these tools opens up new perspectives for assessing the role of short-lived excited states on processes lying underneath organic device operation.
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14
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Soon YW, Clarke TM, Zhang W, Agostinelli T, Kirkpatrick J, Dyer-Smith C, McCulloch I, Nelson J, Durrant JR. Energy versuselectron transfer in organic solar cells: a comparison of the photophysics of two indenofluorene: fullerene blend films. Chem Sci 2011. [DOI: 10.1039/c0sc00606h] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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15
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Lee YH, Yabushita A, Hsu CS, Yang SH, Iwakura I, Luo CW, Wu KH, Kobayashi T. Ultrafast relaxation dynamics of photoexcitations in poly(3-hexylthiophene) for the determination of the defect concentration. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.08.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Affiliation(s)
- Tracey M Clarke
- Centre for Plastic Electronics, Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
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17
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Qiu Y, Zhu LP. Field effect on polaron dynamics and charge transport in conducting polymers. J Chem Phys 2009; 131:134903. [PMID: 19814571 DOI: 10.1063/1.3243682] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the formation and motion dynamics of polarons in one-dimensional conjugated polymers within the extended Su-Schrieffer-Heeger model combined with an adiabatic dynamics method. In the presence of external electric fields, the initial location of the polaron is stressed and concerned with the charge transport property of organic semiconductors. Three regimes for the electric fields are categorized in terms of the forming place of the polaron. In the low field strength regime, the polaron is formed around the center of the chain and thus the charge undergoes a long-time travel before being extracted into the electrode because of the strong electron and phonon (e-p) interaction. In the intermediate strength regime, the polaron is formed near the chain end. Due to the chain-end scattering, the electron mobility increases in linear relation with the field strength. In the high strength regime, the polaron is formed at the chain end. This results in a nonlinear enhancement in the electronic mobility, in agreement with the experimental observations on the field dependent transient photocurrent in poly(phenylene vinylene). The electron-electron correlation, as well as the field mode effect on polaron dynamics, is also discussed.
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Affiliation(s)
- Yu Qiu
- Department of Physics, Zhejiang Normal University, Jinhua, 321004 Zhejiang, China.
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18
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Sugimoto T, Habuchi S, Ogino K, Vacha M. Conformation-Related Exciton Localization and Charge-Pair Formation in Polythiophenes: Ensemble and Single-Molecule Study. J Phys Chem B 2009; 113:12220-6. [DOI: 10.1021/jp9060945] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Toshikazu Sugimoto
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1-S8, Meguro-ku, Tokyo 152-8552, Japan, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Satoshi Habuchi
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1-S8, Meguro-ku, Tokyo 152-8552, Japan, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Kenji Ogino
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1-S8, Meguro-ku, Tokyo 152-8552, Japan, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Martin Vacha
- Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Ookayama 2-12-1-S8, Meguro-ku, Tokyo 152-8552, Japan, Graduate School of Bio-Applications and System Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
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19
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Ruseckas A, Shaw PE, Samuel IDW. Probing the nanoscale phase separation in binary photovoltaic blends of poly(3-hexylthiophene) and methanofullerene by energy transfer. Dalton Trans 2009:10040-3. [DOI: 10.1039/b912198f] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Abstract
Herein, we focus on the principles of photoconduction in random semiconductors-the key processes being optical generation of charge carriers and their subsequent transport. This is not an overview of the current work in this area, but rather a highlight of elementary processes, their involvement in modern devices and a summary of recent developments and achievements. Experimental results and models are discussed briefly to visualize the mechanism of optical charge generation in pure and doped organic solids. We show current limits of models based on the Onsager theory of charge generation. After the introduction of experimental techniques to characterize charge transport, the hopping concept for transport in organic semiconductors is outlined. The peculiarities of the transport of excitons and charges in disorderd organic semiconductors are highlighted. Finally, a short discussion of ultrafast transport and single chain transport completes the review.
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Affiliation(s)
- Dirk Hertel
- Institute of Physical Chemistry, University of Cologne, Luxemburger Str. 116, 50939 Cologne, Germany.
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21
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Meng Y, Di B, Liu XJ, An Z, Wu CQ. Interchain coupling effects on dynamics of photoexcitations in conjugated polymers. J Chem Phys 2008; 128:184903. [PMID: 18532844 DOI: 10.1063/1.2912190] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Within an extended Su-Schrieffer-Heeger model including interchain interactions and the extended Hubbard model, the dynamical relaxation of photoexcitations in two coupled conjugated polymer chains is investigated by using a nonadiabatic evolution method. Initially, one of the two chains is photoexcited and the other chain is in the dimerized ground state. Due to the interchain interactions, the electron and/or the hole can be transferred from one chain to the other chain. For weak interchain coupling, the dynamical evolution of the lattice on the photoexcited chain is similar to that found in an isolate single chain case. With interchain interactions increasing, the amplitude of the distortions on the photoexcited chain decreases, and simultaneously, that on the other chain gradually increases. Until stronger interchain coupling, the deformations of the two chains have almost the same amplitude. Besides intrachain polaron-excitons and intrachain oppositely charged polaron pairs as found in single chain case, interchain polaron-excitons and interchain separated charged polaron pairs are obtained. The results show that the yield of interchain products increases and that of intrachain products decreases with interchain coupling increasing. Totally, the yield of charged polarons (including intrachain oppositely charged polaron pairs and interchain oppositely charged polaron pairs) is about 25%, in good agreement with results from experiments.
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Affiliation(s)
- Y Meng
- College of Physics, Hebei Normal University, Shijiazhuang, China
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Gulbinas V, Minevičiūtė I, Hertel D, Wellander R, Yartsev A, Sundström V. Exciton diffusion and relaxation in methyl-substituted polyparaphenylene polymer films. J Chem Phys 2007; 127:144907. [DOI: 10.1063/1.2790901] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Scheblykin IG, Yartsev A, Pullerits T, Gulbinas V, Sundström V. Excited State and Charge Photogeneration Dynamics in Conjugated Polymers. J Phys Chem B 2007; 111:6303-21. [PMID: 17521181 DOI: 10.1021/jp068864f] [Citation(s) in RCA: 217] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Conjugated polymers are becoming interesting materials for a range of optoelectronic applications. However, their often complex electronic and structural properties prevent establishment of straightforward property-function relationships. In this paper, we summarize recent results on the photophysics and excited state dynamics of conjugated polymers, in order to paint a picture of exciton formation, quenching, and generation of charge carriers.
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Affiliation(s)
- Ivan G Scheblykin
- Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
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Ai X, Anderson N, Guo J, Kowalik J, Tolbert LM, Lian T. Ultrafast Photoinduced Charge Separation Dynamics in Polythiophene/SnO2 Nanocomposites. J Phys Chem B 2006; 110:25496-503. [PMID: 17165998 DOI: 10.1021/jp0652291] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a study of photoinduced interfacial electron transfer (ET) dynamics of SnO2 nanocrystalline thin films sensitized by polythiophene derivatives (regioregular poly(3-hexylthiophene) (P3HT) and regiorandom poly(3-undecyl-2,2'-bithiophene) (P3UBT)). ET dynamics were measured by following the dynamics of injected electrons in SnO2 and polarons in the conjugated polymer using ultrafast mid-IR transient absorption spectroscopy. The rate of electron transfer from P3HT and P3UBT to SnO2 films was determined to occur on sub-picosecond time scale (120 +/- 20 fs). In P3HT/SnO2 composite, interchain charge transfer was found to compete with and reduce the quantum efficiency of interfacial electron transfer at high polymer loading. This interchain charge separation processes can be reduced in non-regioregular polymer or at low polymer loading levels.
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Affiliation(s)
- Xin Ai
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, USA
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Ai X, Beard MC, Knutsen KP, Shaheen SE, Rumbles G, Ellingson RJ. Photoinduced Charge Carrier Generation in a Poly(3-hexylthiophene) and Methanofullerene Bulk Heterojunction Investigated by Time-Resolved Terahertz Spectroscopy. J Phys Chem B 2006; 110:25462-71. [PMID: 17165994 DOI: 10.1021/jp065212i] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report on the ultrafast photoinduced charge separation processes in varying compositions of poly(3-hexylthiophene) (P3HT) blended with the electron acceptor [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Through the use of time-resolved terahertz spectroscopy, the time- and frequency-dependent complex photoconductivity is measured for samples with PCBM weight fractions (WPCBM) of 0, 0.2, 0.5, and 0.8. By analysis of the frequency-dependent complex conductivity, both the charge carrier yield and the average charge carrier mobility have been determined analytically and indicate a short (<0.2 nm) carrier mean free path and a suppressed long-range transport that is characteristic of carrier localization. Studies on pure films of P3HT demonstrate that charge carrier generation is an intrinsic feature of the polymer that occurs on the time scale of the excitation light, and this is attributed to the dissociation of bound polaron pairs that reside on adjacent polymer chains due to interchain charge transfer. Both interchain and interfacial charge transfer contribute to the measured photoconductivity from the blended samples; interfacial charge transfer increases as a function of increasing PCBM. The addition of PCBM to the polymer films surprisingly does not dramatically increase the production of charge carriers within the first 2 ps. However, charge carriers in the 0.2 and 0.5 blended films survive to much longer times than those in the P3HT and 0.8 films.
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Affiliation(s)
- Xin Ai
- National Renewable Energy Laboratory, Golden, Colorado 80401, USA
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26
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Ruseckas A, Samuel IDW. Exciton self-trapping in MEH-PPV films studied by ultrafast emission depolarization. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/pssc.200562715] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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27
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Toele P, van Gorp JJ, Glasbeek M. Femtosecond Fluorescence Studies of Self-Assembled Helical Aggregates in Solution. J Phys Chem A 2005; 109:10479-87. [PMID: 16834302 DOI: 10.1021/jp053339m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
For the diamino-bipyridine based C(3)-symmetrical disk molecule, TAB, (sub)picosecond fluorescence transients have been observed by means of femtosecond fluorescence upconversion and picosecond time-correlated photon counting techniques. The dodecyl peripheral side chains of the synthetic compound are large enough to allow, in apolar solvents, self-assembling of the discotic molecules to helical aggregates. In polar solvents, the hydrogen bonding and pi-pi interactions pertaining to the chiral aggregation are compensated by solvation and self-assembling of the disklike molecules is disrupted. For comparison, time-resolved fluorescence measurements have been performed for the subgroup molecule, DAC, which is the (asymmetric) building block for TAB. It is concluded that, after pulsed photoexcitation, TAB and DAC exhibit excited-state intramolecular double proton transfer (ESIDPT) with a typical time of approximately 200-300 fs, irrespective of the degree of aggregation. Picosecond components in the fluorescence of TAB and DAC, ranging from 3 to 25 ps, are representative of vibrational cooling effects in the excited product state. Only aggregated TAB shows a rapid ( approximately 1 ps) decay of its fluorescence anisotropy. This component is attributed to excited-state energy transfer within the aggregate. Finally, the excited-state lifetime of TAB in the aggregated form is found to be an order of magnitude longer than that for TAB in its nonaggregated form. It is inferred that aggregation diminishes the influence of low-frequency twisting motions in the radiationless decay of the excited state.
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Affiliation(s)
- Paul Toele
- Laboratory for Physical Chemistry, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS Amsterdam, The Netherlands
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An Z, Wu CQ, Sun X. Dynamics of photogenerated polarons in conjugated polymers. PHYSICAL REVIEW LETTERS 2004; 93:216407. [PMID: 15601042 DOI: 10.1103/physrevlett.93.216407] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Indexed: 05/24/2023]
Abstract
Within a tight-binding electron-phonon interacting model, we investigate the dynamics of photoexcitations to address the generation mechanism of charged polarons in conjugated polymers by using a nonadiabatic evolution method. Besides the neutral polaron exciton which is well known, we identify a novel product of lattice dynamic relaxation from the photoexcited states in a few hundreds of femtoseconds, which is a mixed state composed of both charged polarons and neutral excitons. Our results show that the charged polarons are generated directly with a yield of about 25%, which is independent of the excitation energies, in good agreement with results from experiments. Effects of the conjugation length are also discussed.
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Affiliation(s)
- Z An
- Research Center for Theoretical Physics, Fudan University, Shanghai 200433, China
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Polívka T, Pullerits T, Frank HA, Cogdell RJ, Sundström V. Ultrafast Formation of a Carotenoid Radical in LH2 Antenna Complexes of Purple Bacteria. J Phys Chem B 2004. [DOI: 10.1021/jp0483019] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomáš Polívka
- Department of Chemical Physics, Lund University, Box 124, S-22100 Lund, Sweden, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, and Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K
| | - Tõnu Pullerits
- Department of Chemical Physics, Lund University, Box 124, S-22100 Lund, Sweden, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, and Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K
| | - Harry A. Frank
- Department of Chemical Physics, Lund University, Box 124, S-22100 Lund, Sweden, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, and Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K
| | - Richard J. Cogdell
- Department of Chemical Physics, Lund University, Box 124, S-22100 Lund, Sweden, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, and Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K
| | - Villy Sundström
- Department of Chemical Physics, Lund University, Box 124, S-22100 Lund, Sweden, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, and Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, U.K
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Hilczer M, Bandyopadhyay T, Tachiya M. Electric field effect on electron transfer between donor and acceptor in polymer matrix. J Photochem Photobiol A Chem 2004. [DOI: 10.1016/j.jphotochem.2004.04.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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31
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Im C, Tian W, Bässler H, Fechtenkötter A, Watson MD, Müllen K. Photoconduction in organic donor–acceptor systems. J Chem Phys 2003. [DOI: 10.1063/1.1590954] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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33
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Gulbinas V, Zaushitsyn Y, Sundström V, Hertel D, Bässler H, Yartsev A. Dynamics of the electric field-assisted charge carrier photogeneration in ladder-type poly(para-phenylene) at a low excitation intensity. PHYSICAL REVIEW LETTERS 2002; 89:107401. [PMID: 12225224 DOI: 10.1103/physrevlett.89.107401] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2001] [Indexed: 05/23/2023]
Abstract
Electric field-assisted charge carrier photogeneration in a ladder-type methyl-substituted poly(paraphenylene) was investigated by ultrafast absorption spectroscopy at low excitation intensity. The dissociation of excitons into electron-hole pairs occurs from the vibrationally relaxed excited state throughout its lifetime and is caused by the applied electric field, rather than by existence of special "dissociation sites." These findings are of importance for material choice in device applications.
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Ruseckas A, Namdas EB, Ganguly T, Theander M, Svensson M, Andersson MR, Inganäs O, Sundström V. Intra- and Interchain Luminescence in Amorphous and Semicrystalline Films of Phenyl-Substituted Polythiophene. J Phys Chem B 2001. [DOI: 10.1021/jp010511n] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Arvydas Ruseckas
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Ebinazar B. Namdas
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Tapan Ganguly
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Mathias Theander
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Mattias Svensson
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Mats R. Andersson
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Olle Inganäs
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
| | - Villy Sundström
- Department of Chemical Physics, Lund University, Box 124, SE-22100 Lund, Sweden, Laboratory of Applied Physics, Department of Physics and Measurement Technology (IFM), Linköping University, SE-58183 Linköping, Sweden, and Departments of Organic Chemistry and Polymer Technology, Chalmers University of Technology, SE-41296 Göteborg, Sweden
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36
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Conformational disorder of a substituted polythiophene in solution revealed by excitation transfer. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00305-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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