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Hofer S, Unterkofler J, Kaltenegger M, Schweicher G, Ruzié C, Tamayo A, Salzillo T, Mas-Torrent M, Sanzone A, Beverina L, Geerts YH, Resel R. Molecular Disorder in Crystalline Thin Films of an Asymmetric BTBT Derivative. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2021; 33:1455-1461. [PMID: 33642680 PMCID: PMC7905871 DOI: 10.1021/acs.chemmater.0c04725] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 01/27/2021] [Indexed: 06/02/2023]
Abstract
The molecule 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10) is an organic semiconductor with outstanding performance in thin-film transistors. The asymmetric shape of the molecule causes an unusual phase behavior, which is a result of a distinct difference in the molecular arrangement between the head-to-head stacking of the molecules versus head-to-tail stacking. Thin films are prepared at elevated temperatures by crystallization from melt under controlled cooling rates, thermal-gradient crystallization, and bar coating at elevated temperatures. The films are investigated using X-ray diffraction techniques. Unusual peak-broadening effects are found, which cannot be explained using standard models. The modeling of the diffraction patterns with a statistic variation of the molecules reveal that a specific type of molecular disorder is responsible for the observed peak-broadening phenomena: the known head-to-head stacking within the crystalline phase is disturbed by the statistic integration of reversed (or flipped) molecules. It is found that 7-15% of the molecules are integrated in a reversed way, and these fractions are correlated with cooling rates during the sample preparation procedure. Temperature-dependent in situ experiments reveal that the defects can be healed by approaching the transition from the crystalline state to the smectic E state at a temperature of 145 °C. This work identifies and quantifies a specific crystalline defect type within thin films of an asymmetric rodlike conjugated molecule, which is caused by the crystallization kinetics.
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Affiliation(s)
- Sebastian Hofer
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
| | - Johanna Unterkofler
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
| | - Martin Kaltenegger
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
| | - Guillaume Schweicher
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
| | - Christian Ruzié
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
| | - Adrián Tamayo
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain
| | - Tommaso Salzillo
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain
| | - Marta Mas-Torrent
- Institut
de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193 Bellaterra, Spain
| | - Alessandro Sanzone
- Department
of Materials Science, University of Milano-Bicocca, Via Roberto Cozzi, 55, Milano 20125, Italy
| | - Luca Beverina
- Department
of Materials Science, University of Milano-Bicocca, Via Roberto Cozzi, 55, Milano 20125, Italy
| | - Yves Henry Geerts
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard
du, Triomphe, Bruxelles 1050, Belgium
- Laboratoire
de Chimie des Polymères, Faculté des Sciences, International
Solvay Institutes of Physics and Chemistry, Université Libre de Bruxelles, Campus Plaine, CP206/01 - Boulevard du Triomphe, Brussels 1050, Belgium
| | - Roland Resel
- Institute
of Solid State Physics, Graz University of Technology, Petersgasse 16, Graz 8010, Austria
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Physical Modeling of Activation Energy in Organic Semiconductor Devices based on Energy and Momentum Conservations. Sci Rep 2016; 6:24777. [PMID: 27103586 PMCID: PMC4840453 DOI: 10.1038/srep24777] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/04/2016] [Indexed: 11/09/2022] Open
Abstract
Field effect mobility in an organic device is determined by the activation energy. A new physical model of the activation energy is proposed by virtue of the energy and momentum conservation equations. The dependencies of the activation energy on the gate voltage and the drain voltage, which were observed in the experiments in the previous independent literature, can be well explained using the proposed model. Moreover, the expression in the proposed model, which has clear physical meanings in all parameters, can have the same mathematical form as the well-known Meyer-Neldel relation, which lacks of clear physical meanings in some of its parameters since it is a phenomenological model. Thus it not only describes a physical mechanism but also offers a possibility to design the next generation of high-performance optoelectronics and integrated flexible circuits by optimizing device physical parameter.
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Song L, Shi Q. A new approach to calculate charge carrier transport mobility in organic molecular crystals from imaginary time path integral simulations. J Chem Phys 2015; 142:174103. [DOI: 10.1063/1.4919061] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Linze Song
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
| | - Qiang Shi
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China
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Kumar D, Thomas KRJ, Lin CC, Jou JH. Pyrenoimidazole-Based Deep-Blue-Emitting Materials: Optical, Electrochemical, and Electroluminescent Characteristics. Chem Asian J 2013; 8:2111-24. [DOI: 10.1002/asia.201300271] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/16/2013] [Indexed: 12/24/2022]
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Hinderhofer A, Heinemeyer U, Gerlach A, Kowarik S, Jacobs RMJ, Sakamoto Y, Suzuki T, Schreiber F. Optical properties of pentacene and perfluoropentacene thin films. J Chem Phys 2007; 127:194705. [DOI: 10.1063/1.2786992] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Datta A, Mohakud S, Pati SK. Electron and hole mobilities in polymorphs of benzene and naphthalene: Role of intermolecular interactions. J Chem Phys 2007; 126:144710. [PMID: 17444735 DOI: 10.1063/1.2721530] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The hole and electron mobilities of the polymorphs of benzene and naphthalene crystals are estimated through quantum chemical calculations. The reorganization energy (lambda) and the charge-transfer matrix elements (Hmn) calculated for the two molecules reveal that these crystals can be used for dual applications, for both hole and electron conductance. The electron mobilities are five to eight times more than the hole mobilities for benzene while for naphthalene, the hole mobilities are almost an order magnitude more than the electron mobilities. The transfer matrices for both hole and electron conductance decrease monotonically with increase in the intermolecular distances. Calculations for various unique stacked dimers as determined from the radial distribution functions in both the crystals for the two molecules show strong dependence on the orientations of the rings and for similar intermolecular separations; Hmnhole is larger than Hmnelectron. The crystal mobilities are calculated from the weighted average over all the unique pair of molecules. The overall preference in a crystal for hole or electron mobility depends on the mutual competition of lambdahole/lambdaelectron and Hmnhole/Hmnelectron. From our microscopic understanding of essential parameters, specific dimers are identified from the crystalline solids of the two polymorphs and experimental strategies are suggested to enrich such pairs in aggregates for enhancing mobilities for these organic solids.
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Affiliation(s)
- Ayan Datta
- Theoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur Campus, Bangalore 560064, India
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Vollmer A, Jurchescu OD, Arfaoui I, Salzmann I, Palstra TTM, Rudolf P, Niemax J, Pflaum J, Rabe JP, Koch N. The effect of oxygen exposure on pentacene electronic structure. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2005; 17:339-43. [PMID: 15968478 DOI: 10.1140/epje/i2005-10012-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Accepted: 04/21/2005] [Indexed: 05/03/2023]
Abstract
We use ultraviolet photoelectron spectroscopy to investigate the effect of oxygen and air exposure on the electronic structure of pentacene single crystals and thin films. It is found that O(2) and water do not react noticeably with pentacene, whereas singlet oxygen/ozone readily oxidize the organic compound. Also, we obtain no evidence for considerable p-type doping of pentacene by O(2) at low pressure. However, oxygen exposure lowers the hole injection barrier at the interface between Au and pentacene by 0.25 eV, presumably due to a modification of the Au surface properties.
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Affiliation(s)
- A Vollmer
- Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung m.b.H., Berlin, Germany
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Günther C, Karl N, Pflaum J, Strohmaier R, Gompf B, Eisenmenger W, Müller M, Müllen K. LEED, STM, and TDS studies of ordered thin films of the rhombus-shaped polycondensed aromatic hydrocarbon C54H22, on MoS2, GeS, and graphite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:656-665. [PMID: 15641836 DOI: 10.1021/la048009s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Low-energy electron diffraction (LEED), scanning tunneling microscopy (STM), and thermal desorption spectroscopy (TDS) are used to study vacuum vapor-deposited molecular thin films of the rhombus-shaped polycondensed aromatic hydrocarbon "rhombus-C54", C54H22, on MoS2 and graphite (0001) and on GeS (010) substrates. It is found that this compound forms well-ordered incommensurate superstructures of the closest packed flat-lying molecules in well-defined azimuthal orientations to the substrate. These films are thermally remarkably stable. By TDS, a monolayer binding energy on graphite of 2.3 eV was derived, whereas the molecules in the second layer were found to be less strongly bound (1.9 eV). This difference allows the preparation of monolayers by desorbing multilayers at the appropriate temperature. Apparently, this molecule is a promising candidate for further studies aiming at applications in organic electronics such as organic field effect transistors or light emitting displays.
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Affiliation(s)
- Christian Günther
- Physikalisches Institut, Universität Stuttgart, D-70550 Stuttgart, Germany
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