1
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Unger F, Lepple D, Asbach M, Craciunescu L, Zeiser C, Kandolf AF, Fišer Z, Hagara J, Hagenlocher J, Hiller S, Haug S, Deutsch M, Grüninger P, Novák J, Bettinger HF, Broch K, Engels B, Schreiber F. Optical Absorption Properties in Pentacene/Tetracene Solid Solutions. J Phys Chem A 2024; 128:747-760. [PMID: 38232326 DOI: 10.1021/acs.jpca.3c06737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
Modifying the optical and electronic properties of crystalline organic thin films is of great interest for improving the performance of modern organic semiconductor devices. Therein, the statistical mixing of molecules to form a solid solution provides an opportunity to fine-tune optical and electronic properties. Unfortunately, the diversity of intermolecular interactions renders mixed organic crystals highly complex, and a holistic picture is still lacking. Here, we report a study of the optical absorption properties in solid solutions of pentacene and tetracene, two prototypical organic semiconductors. In the mixtures, the optical properties can be continuously modified by statistical mixing at the molecular level. Comparison with time-dependent density functional theory calculations on occupationally disordered clusters unravels the electronic origin of the low energy optical transitions. The disorder partially relaxes the selection rules, leading to additional optical transitions that manifest as optical broadening. Furthermore, the contribution of diabatic charge-transfer states is modified in the mixtures, reducing the observed splitting in the 0-0 vibronic transition. Additional comparisons with other blended systems generalize our results and indicate that changes in the polarizability of the molecular environment in organic thin-film blends induce shifts in the absorption spectrum.
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Affiliation(s)
- Frederik Unger
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Daniel Lepple
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Maximilian Asbach
- Julius-Maximilian University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Luca Craciunescu
- Julius-Maximilian University Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS Scotland, U.K
| | - Clemens Zeiser
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Andreas F Kandolf
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Zbyněk Fišer
- Department of Condensed Matter Physics (UFKL), Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Jakub Hagara
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Jan Hagenlocher
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Stefan Hiller
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Sara Haug
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Marian Deutsch
- Julius-Maximilian University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Peter Grüninger
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Jiří Novák
- Department of Condensed Matter Physics (UFKL), Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic
| | - Holger F Bettinger
- Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Katharina Broch
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Bernd Engels
- Julius-Maximilian University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Frank Schreiber
- Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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2
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Craciunescu L, Asbach M, Wirsing S, Hammer S, Unger F, Broch K, Schreiber F, Witte G, Dreuw A, Tegeder P, Fantuzzi F, Engels B. Cluster-Based Approach Utilizing Optimally Tuned TD-DFT to Calculate Absorption Spectra of Organic Semiconductor Thin Films. J Chem Theory Comput 2023; 19:9369-9387. [PMID: 38073092 DOI: 10.1021/acs.jctc.3c01107] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
The photophysics of organic semiconductor (OSC) thin films or crystals has garnered significant attention in recent years since a comprehensive theoretical understanding of the various processes occurring upon photoexcitation is crucial for assessing the efficiency of OSC materials. To date, research in this area has relied on methods using Frenkel-Holstein Hamiltonians, calculations of the GW-Bethe-Salpeter equation with periodic boundaries, or cluster-based approaches using quantum chemical methods, with each of the three approaches having distinct advantages and disadvantages. In this work, we introduce an optimally tuned, range-separated time-dependent density functional theory approach to accurately reproduce the total and polarization-resolved absorption spectra of pentacene, tetracene, and perylene thin films, all representative OSC materials. Our approach achieves excellent agreement with experimental data (mostly ≤0.1 eV) when combined with the utilization of clusters comprising multiple monomers and a standard polarizable continuum model to simulate the thin-film environment. Our protocol therefore addresses a major drawback of cluster-based approaches and makes them attractive tools for OSC investigations. Its key advantages include its independence from external, system-specific fitting parameters and its straightforward application with well-known quantum chemical program codes. It demonstrates how chemical intuition can help to reduce computational cost and still arrive at chemically meaningful and almost quantitative results.
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Affiliation(s)
- Luca Craciunescu
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS Scotland, U.K
| | - Maximilian Asbach
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
| | - Sara Wirsing
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
| | - Sebastian Hammer
- Experimentelle Physik VI, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for the Physics of Materials, Department of Physics and Department of Chemistry, McGill University, 801 Sherbrooke St. W, Montreal, H3A 2K6 Québec, Canada
| | - Frederik Unger
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Katharina Broch
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Gregor Witte
- Molekulare Festkörperphysik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Andreas Dreuw
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Universität Heidelberg, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany
| | - Petra Tegeder
- Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany
| | - Felipe Fantuzzi
- School of Chemistry and Forensic Science, University of Kent, Park Wood Rd, CT2 7NH Canterbury, U.K
| | - Bernd Engels
- Institut für Physikalische und Theoretische Chemie, Julius-Maximilians-Universität Würzburg, Emil-Fischer-Str. 42, 97074 Würzburg, Germany
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3
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Kefer O, Ahrens L, Han J, Wollscheid N, Misselwitz E, Rominger F, Freudenberg J, Dreuw A, Bunz UHF, Buckup T. Efficient Intramolecular Singlet Fission in Spiro-Linked Heterodimers. J Am Chem Soc 2023; 145:17965-17974. [PMID: 37535495 DOI: 10.1021/jacs.3c05518] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
We investigate intramolecular singlet fission (iSF) of spiro-linked azaacene heterodimers by time-resolved spectroscopy and quantum chemical calculations. Combining two different azaacenes through a nonconjugated linker using condensation chemistry furnishes azaacene heterodimers. Compared to their homodimers, iSF quantum yields are improved at an extended absorption range. The driving force of iSF, the energy difference ΔEiSF between the S1 state and the correlated triplet pair 1(TT), is tuned by the nature of the heterodimers. iSF is exothermic in all of the herein studied molecules. The overall quantum yield for triplet exciton formation reaches approximately 174%. This novel concept exploits large energy differences between singlet electronic states in combination with spatially fixed chromophores, which achieves efficient heterogeneous iSF, if the through-space interaction between the chromophores is minimal.
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Affiliation(s)
- Oskar Kefer
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
- Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Lukas Ahrens
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Jie Han
- Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Nikolaus Wollscheid
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
- Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Erik Misselwitz
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Frank Rominger
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Jan Freudenberg
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Andreas Dreuw
- Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Uwe H F Bunz
- Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Tiago Buckup
- Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
- Centre for Advanced Materials, Ruprecht-Karls-Universität Heidelberg, D-69120 Heidelberg, Germany
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4
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Theurer CP, Laible F, Tang J, Broch K, Fleischer M, Schreiber F. Strong light-matter coupling in pentacene thin films on plasmonic arrays. NANOSCALE 2023. [PMID: 37387269 DOI: 10.1039/d3nr01108a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
Utilizing strong light-matter coupling is an elegant and powerful way to modify the energy landscapes of excited states of organic semiconductors. Consequently, the chemical and photophysical properties of these organic semiconductors can be influenced without the need of chemical modification but simply by implementing them in optical microcavities. This has so far mostly been shown in Fabry-Pérot cavities and with organic single crystals or diluted molecules in a host matrix. Here, we demonstrate strong, simultaneous coupling of the two Davydov transitions in polycrystalline pentacene thin films to surface lattice resonances supported by open cavities made of silver nanoparticle arrays. Such thin films are more easily fabricated and, together with the open architecture, more suitable for device applications.
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Affiliation(s)
- Christoph P Theurer
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Florian Laible
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Jia Tang
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
| | - Katharina Broch
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Universität Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Monika Fleischer
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Universität Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
- Center for Light-Matter Interaction, Sensors & Analytics (LISA+), Universität Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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5
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Gorkowski K, Benedict KB, Carrico CM, Dubey MK. Complexities in Modeling Organic Aerosol Light Absorption. J Phys Chem A 2022; 126:4827-4833. [PMID: 35834798 PMCID: PMC9340763 DOI: 10.1021/acs.jpca.2c02236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 07/04/2022] [Indexed: 11/29/2022]
Abstract
Aerosol particles dynamically evolve in the atmosphere by physicochemical interactions with sunlight, trace chemical species, and water. Current modeling approaches fix properties such as aerosol refractive index, introducing spatial and temporal errors in the radiative impacts. Further progress requires a process-level description of the refractive indices as the particles age and experience physicochemical transformations. We present two multivariate modeling approaches of light absorption by brown carbon (BrC). The initial approach was to extend the modeling framework of the refractive index at 589 nm (nD), but that result was insufficient. We developed a second multivariate model using aromatic rings and functional groups to predict the imaginary part of the complex refractive index. This second model agreed better with measured spectral absorption peaks, showing promise for a simplified treatment of BrC optics. In addition to absorption, organic functionalities also alter the water affinity of the molecules, leading to a hygroscopic uptake and increased light absorption, which we show through measurements and modeling.
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Affiliation(s)
- Kyle Gorkowski
- Earth
and Environmental Science, Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, United States
| | - Katherine B. Benedict
- Earth
and Environmental Science, Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, United States
| | - Christian M. Carrico
- New
Mexico Institute of Mining and Technology, Socorro, New Mexico 87801, United States
| | - Manvendra K. Dubey
- Earth
and Environmental Science, Los Alamos National
Laboratory, Los Alamos, New Mexico 87545, United States
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6
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Huang LY, Ai Q, Risko C. The Role of Crystal Packing on the Optical Response of Trialkyltetrelethynyl Acenes. J Chem Phys 2022; 157:084703. [DOI: 10.1063/5.0097421] [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
The electronic and optical responses of an organic semiconductor (OSC) are dictated by the chemistries of the molecular or polymer building blocks and how these chromophores pack in the solid state. Understanding the physicochemical natures of these responses are not only critical for determining OSC performance for a particular application, but the UV/visible optical response may also be of potential use to determine aspects of the molecular-scale solid-state packing for crystal polymorphs or thin-film morphologies that are difficult to determine otherwise. To probe these relationships, we report the quantum-chemical investigation of a series of trialkyltetrelethynyl acenes (tetrel = silicon or germanium) that adopt the brickwork (BW), slip-stack (SS), or herringbone (HB) packing configurations; the π-conjugated backbones considered here are pentacene (PEN) and anthradithiophene (ADT). For comparison, HB-packed (unsubstituted) pentacene is also included. Density functional theory (DFT) and G0W0 (single-shot GW) electronic band structures, G0W0-BSE (Bethe-Salpeter Equation)-derived optical spectra, polarized ϵ2 spectra, and distributions of both singlet and triplet exciton wave functions are reported. Configurational disorder is also considered. Further, we evaluate the probability of singlet fission in these materials through energy conservation relationships.
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Affiliation(s)
| | - Qianxiang Ai
- Chemistry, Fordham University - Rose Hill Campus, United States of America
| | - Chad Risko
- Chemistry, University of Kentucky, United States of America
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7
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Ashoka A, Tamming RR, Girija AV, Bretscher H, Verma SD, Yang SD, Lu CH, Hodgkiss JM, Ritchie D, Chen C, Smith CG, Schnedermann C, Price MB, Chen K, Rao A. Extracting quantitative dielectric properties from pump-probe spectroscopy. Nat Commun 2022; 13:1437. [PMID: 35301311 PMCID: PMC8931171 DOI: 10.1038/s41467-022-29112-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 02/21/2022] [Indexed: 11/21/2022] Open
Abstract
Optical pump-probe spectroscopy is a powerful tool for the study of non-equilibrium electronic dynamics and finds wide applications across a range of fields, from physics and chemistry to material science and biology. However, a shortcoming of conventional pump-probe spectroscopy is that photoinduced changes in transmission, reflection and scattering can simultaneously contribute to the measured differential spectra, leading to ambiguities in assigning the origin of spectral signatures and ruling out quantitative interpretation of the spectra. Ideally, these methods would measure the underlying dielectric function (or the complex refractive index) which would then directly provide quantitative information on the transient excited state dynamics free of these ambiguities. Here we present and test a model independent route to transform differential transmission or reflection spectra, measured via conventional optical pump-probe spectroscopy, to changes in the quantitative transient dielectric function. We benchmark this method against changes in the real refractive index measured using time-resolved Frequency Domain Interferometry in prototypical inorganic and organic semiconductor films. Our methodology can be applied to existing and future pump-probe data sets, allowing for an unambiguous and quantitative characterisation of the transient photoexcited spectra of materials. This in turn will accelerate the adoption of pump-probe spectroscopy as a facile and robust materials characterisation and screening tool. Photoinduced changes in transmission, reflection and scattering prevent conventional pump-probe spectroscopy to unambiguously assign the origin of spectral signatures. Ashoka et al. have developed an optical modelling technique to extract quantitative and unambiguous changes in the dielectric function from standard pump-probe measurements.
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Affiliation(s)
- Arjun Ashoka
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Ronnie R Tamming
- Robinson Research Institute, Faculty of Engineering, Victoria University of Wellington, Wellington, 6012, New Zealand.,School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6012, New Zealand.,MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand
| | - Aswathy V Girija
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Hope Bretscher
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Sachin Dev Verma
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK.,Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal Bypass Road, Bhopal, 462066, Madhya Pradesh, India
| | - Shang-Da Yang
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Chih-Hsuan Lu
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Justin M Hodgkiss
- School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6012, New Zealand.,MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand
| | - David Ritchie
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Chong Chen
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Charles G Smith
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Christoph Schnedermann
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK
| | - Michael B Price
- School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, 6012, New Zealand.,MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand
| | - Kai Chen
- Robinson Research Institute, Faculty of Engineering, Victoria University of Wellington, Wellington, 6012, New Zealand.,MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand.,The Dodd-Walls Centre for Photonic and Quantum Technologies, Dunedin, 9016, New Zealand
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, UK.
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8
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Wagner T, Antczak G, Ghanbari E, Navarro-Quezada A, Györök M, Volokitina A, Marschner F, Zeppenfeld P. Standard deviation of microscopy images used as indicator for growth stages. Ultramicroscopy 2022; 233:113427. [PMID: 34990906 DOI: 10.1016/j.ultramic.2021.113427] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/18/2021] [Accepted: 11/12/2021] [Indexed: 11/29/2022]
Abstract
Photoelectron emission microscopy (PEEM) and low energy electron microscopy (LEEM) can easily distinguish between organic molecules adsorbed in crystallites or in the wetting layers as well as the bare metal substrate due to their different electronic properties. Already before (and during) the condensation of such solid phases (2D islands or 3D crystallites), there is a dilute 2D gas phase. Such a 2D gas phase consists of molecules, which are highly mobile and diffuse across the surface. The individual molecules are too small to be resolved in PEEM/LEEM images. Here, we discuss, how image features below and above the resolution limit of a PEEM/LEEM affect the mean electron yield and its (normalized) standard deviation. We support our findings with two experimental examples: the deposition of cobalt phthalocyanine (CoPc) on Ag(100) and of perfluoro-pentacene on Ag(110). Our results demonstrate, how a spatial and temporal analysis of image series can be used to obtain information about molecular phases, which cannot be directly resolved in microscopy images.
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Affiliation(s)
- Thorsten Wagner
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria.
| | - Grażyna Antczak
- University of Wrocław, Institute of Experimental Physics, Pl. M. Borna 9, 50-204 Wrocław, Poland.
| | - Ebrahim Ghanbari
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria
| | - Andrea Navarro-Quezada
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria; Johannes Kepler University, Institute of Semiconductor and Solid State Physics, Quantum Materials Group, Altenberger Str. 69, 4040 Linz, Austria.
| | - Michael Györök
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria.
| | - Anna Volokitina
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria
| | - Felix Marschner
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria
| | - Peter Zeppenfeld
- Johannes Kepler University, Institute of Experimental Physics, Surface Science Division, Altenberger Str. 69, 4040 Linz, Austria.
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9
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Günder D, Valencia AM, Guerrini M, Breuer T, Cocchi C, Witte G. Polarization Resolved Optical Excitation of Charge-Transfer Excitons in PEN:PFP Cocrystalline Films: Limits of Nonperiodic Modeling. J Phys Chem Lett 2021; 12:9899-9905. [PMID: 34610238 DOI: 10.1021/acs.jpclett.1c02761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Charge-transfer excitons (CTXs) at organic donor/acceptor interfaces are considered important intermediates for charge separation in photovoltaic devices. Crystalline model systems provide microscopic insights into the nature of such states as they enable microscopic structure-property investigations. Here, we use angular-resolved UV/vis absorption spectroscopy to characterize the CTXs of crystalline pentacene:perfluoro-pentacene (PEN:PFP) films allowing determination of the polarization of this state. This analysis is complemented by first-principles many-body calculations, performed on the three-dimensional PEN:PFP cocrystal, which confirm that the lowest-energy excitation is a CTX. Analogous simulations performed on bimolecular clusters are unable to reproduce this state. We ascribe this failure to the lack of long-range interactions and wave function periodicity in these cluster calculations, which appear to remain a valid tool for modeling properties of organic materials ruled by local intermolecular couplings.
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Affiliation(s)
- Darius Günder
- Philipps-Universität Marburg, Molekulare Festkörperphysik, 35032 Marburg, Germany
| | - Ana M Valencia
- Carl von Ossietzky Universität Oldenburg, Institute of Physics, Carl-von-Ossietzky-Straße 9, 26129 Oldenburg, Germany
| | - Michele Guerrini
- Carl von Ossietzky Universität Oldenburg, Institute of Physics, Carl-von-Ossietzky-Straße 9, 26129 Oldenburg, Germany
| | - Tobias Breuer
- Philipps-Universität Marburg, Molekulare Festkörperphysik, 35032 Marburg, Germany
| | - Caterina Cocchi
- Carl von Ossietzky Universität Oldenburg, Institute of Physics, Carl-von-Ossietzky-Straße 9, 26129 Oldenburg, Germany
- Humboldt-Universität zu Berlin, Physics Department and IRIS Adlershof, Zum Großen Windkanal 2, 12489 Berlin, Germany
| | - Gregor Witte
- Philipps-Universität Marburg, Molekulare Festkörperphysik, 35032 Marburg, Germany
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10
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Zeiser C, Moretti L, Reicherter F, Bettinger HF, Maiuri M, Cerullo G, Broch K. Singlet Fission in Dideuterated Tetracene and Pentacene. CHEMPHOTOCHEM 2021. [DOI: 10.1002/cptc.202000284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Clemens Zeiser
- Institute for Applied Physics University of Tübingen Auf der Morgenstelle 10 72076 Tübingen Germany
| | - Luca Moretti
- IFN-CNR Dipartimento di Fisica Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milan Italy
| | - Florian Reicherter
- Institute for Organic Chemistry University of Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Holger F. Bettinger
- Institute for Organic Chemistry University of Tübingen Auf der Morgenstelle 18 72076 Tübingen Germany
| | - Margherita Maiuri
- IFN-CNR Dipartimento di Fisica Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milan Italy
| | - Giulio Cerullo
- IFN-CNR Dipartimento di Fisica Politecnico di Milano Piazza Leonardo da Vinci 32 20133 Milan Italy
| | - Katharina Broch
- Institute for Applied Physics University of Tübingen Auf der Morgenstelle 10 72076 Tübingen Germany
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11
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Hammer S, Zeiser C, Deutsch M, Engels B, Broch K, Pflaum J. Spatial Anisotropy of Charge Transfer at Perfluoropentacene-Pentacene (001) Single-Crystal Interfaces and its Relevance for Thin Film Devices. ACS APPLIED MATERIALS & INTERFACES 2020; 12:53547-53556. [PMID: 33167608 DOI: 10.1021/acsami.0c17152] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Archetypal donor-acceptor (D-A) interfaces composed of perfluoropentacene (PFP) and pentacene (PEN) are examined for charge transfer (CT) state formation and energetics as a function of their respective molecular configuration. To exclude morphological interference, our structural as well as highly sensitive differential reflectance spectroscopy studies were carried out on PFP thin films epitaxially grown on PEN(001) single-crystal facets. Whereas the experimental data supported by complementary theoretical calculations confirm the formation of a strong CT state in the case of a cofacial PFP-PEN stacking, CT formation is energetically less favorable and thus absent for the corresponding head-to-tail configuration as disclosed for the first time. In view of technological implementations, the knowledge gained on the single-crystal references is transferred to thin-film diodes composed of either stacked PFP/PEN bilayers or mixed PFP:PEN heterojunction interfaces. As demonstrated, their electronic and electroluminescent behavior can be consistently described by the absence or presence of interfacial CT states. Thus, our results hint at the thorough design of D-A interfaces to achieve the highest device performances.
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Affiliation(s)
- Sebastian Hammer
- Experimental Physics VI, Julius Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Clemens Zeiser
- Institute for Applied Physics, Eberhard Karls University Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Marian Deutsch
- Institute for Physical and Theoretical Chemistry, Julius Maximilians University Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | - Bernd Engels
- Institute for Physical and Theoretical Chemistry, Julius Maximilians University Würzburg, Emil-Fischer-Straße 42, 97074 Würzburg, Germany
| | - Katharina Broch
- Institute for Applied Physics, Eberhard Karls University Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Jens Pflaum
- Experimental Physics VI, Julius Maximilians University Würzburg, Am Hubland, 97074 Würzburg, Germany
- Bavarian Center for Applied Energy Research, Magdalene-Schoch-Straße 3, 97074 Würzburg, Germany
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12
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Wang Q, Chen MT, Franco-Cañellas A, Shen B, Geiger T, F. Bettinger H, Schreiber F, Salzmann I, Gerlach A, Duhm S. Impact of fluorination on interface energetics and growth of pentacene on Ag(111). BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2020; 11:1361-1370. [PMID: 32974114 PMCID: PMC7492695 DOI: 10.3762/bjnano.11.120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 08/19/2020] [Indexed: 05/26/2023]
Abstract
We studied the structural and electronic properties of 2,3,9,10-tetrafluoropentacene (F4PEN) on Ag(111) via X-ray standing waves (XSW), low-energy electron diffraction (LEED) as well as ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS). XSW revealed that the adsorption distances of F4PEN in (sub)monolayers on Ag(111) were 3.00 Å for carbon atoms and 3.05 Å for fluorine atoms. The F4PEN monolayer was essentially lying on Ag(111), and multilayers adopted π-stacking. Our study shed light not only on the F4PEN-Ag(111) interface but also on the fundamental adsorption behavior of fluorinated pentacene derivatives on metals in the context of interface energetics and growth mode.
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Affiliation(s)
- Qi Wang
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Meng-Ting Chen
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People’s Republic of China
| | - Antoni Franco-Cañellas
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Bin Shen
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Thomas Geiger
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Holger F. Bettinger
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Ingo Salzmann
- Department of Physics, Department of Chemistry & Biochemistry, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec H4B 1R6, Canada
| | - Alexander Gerlach
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Steffen Duhm
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices and Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123, People’s Republic of China
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13
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Chuev MA, Prutskov GV, Novikova NN, Pashaev EM, Konovalov OV, Stepina ND, Rogachev AV, Yakunin SN. Theoretical Approach to Analysis of X-Ray Grazing-Incidence Diffraction from 2D Crystals. CRYSTALLOGR REP+ 2020. [DOI: 10.1134/s1063774520050041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Günder D, Watanabe K, Taniguchi T, Witte G. Van der Waals Bound Organic/2D Insulator Hybrid Structures: Epitaxial Growth of Acene Films on hBN(001) and the Influence of Surface Defects. ACS APPLIED MATERIALS & INTERFACES 2020; 12:38757-38767. [PMID: 32846485 DOI: 10.1021/acsami.0c09527] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Combining 2D materials with functional molecular films enables the fabrication of van der Waals bound organic/inorganic hybrids that are of interest for future device architectures. Recently, the 2D dielectric hexagonal boron nitride (hBN) has received particular attention since exfoliation allows the preparation of crystalline layers which have been utilized as ultrathin dielectrics in electronic devices. Here, we have studied the formation and structure of molecular films of the prototypical organic semiconductors pentacene (PEN) and perfluoropentacene (PFP) on hBN. Special attention was paid to the influence of substrate surface defects on the film formation by comparing molecular films that were grown on hBN substrates of various quality, including single crystals (representing the most ideal surface), briefly ion bombarded substrates, and exfoliated flakes. While X-ray diffraction (XRD) yields precise information about the crystalline structure of films grown on (large) single crystals, it is hardly applicable to analyze the films formed on exfoliated flakes because of their small size. Here, we demonstrate that in the case of flakes detailed structural analyses of the molecular films are possible by combining atomic force microscopy (AFM) with microspot UV/vis spectroscopy and optical polarization microscopy. On well-ordered hBN single crystal surfaces both acenes form very smooth and epitaxial crystalline films where molecules adopt a recumbent orientation (even in 100 nm thick films). By contrast, both materials adopt an upright molecular orientation and different polymorphs on defective hBN surfaces and reveal distinctly different film morphologies. On exfoliated flakes, PFP shows a film structure similar to that on the hBN single crystals, while PEN films exhibit a structure as on defective hBN substrates. In addition, a pronounced decoration of defect steps, which are probably created by the exfoliation process, was observed for PEN leading to the formation of tall and extended fibers where molecules adopt a recumbent orientation. The present study reveals different robustness in film growth on exfoliated hBN flakes for various molecules, which has to be considered in their device integration, especially with regard to their optoelectronic properties such as light absorption or charge transport, which depend critically on the molecular orientation and crystalline order.
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Affiliation(s)
- Darius Günder
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan
| | - Gregor Witte
- Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany
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15
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Campos RM, Alves ACPM, Lima MAL, Farinha AFM, Cardoso JPS, Mendes A, Costa JCS, Santos LMNBF. Morphology, Structure, and Dynamics of Pentacene Thin Films and Their Nanocomposites with [C
2
C
1
im][NTf
2
] and [C
2
C
1
im][OTF] Ionic Liquids. Chemphyschem 2020; 21:1814-1825. [DOI: 10.1002/cphc.202000431] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 06/18/2020] [Indexed: 11/09/2022]
Affiliation(s)
- Ricardo M. Campos
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
| | - Alexandre C. P. M. Alves
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
| | - Marco A. L. Lima
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
| | - Artur F. M. Farinha
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
| | - João P. S. Cardoso
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
| | - Adélio Mendes
- LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy Faculdade de Engenharia Universidade do Porto Portugal
| | - José C. S. Costa
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
- LEPABE – Laboratory for Process Engineering, Environment, Biotechnology and Energy Faculdade de Engenharia Universidade do Porto Portugal
| | - Luís M. N. B. F. Santos
- CIQUP – Centro de Investigação em Química Departamento de Química e Bioquímica Faculdade de Ciências Universidade do Porto Portugal
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16
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Duva G, Mann A, Pithan L, Beyer P, Hagenlocher J, Gerlach A, Hinderhofer A, Schreiber F. Template-Free Orientation Selection of Rod-Like Molecular Semiconductors in Polycrystalline Films. J Phys Chem Lett 2019; 10:1031-1036. [PMID: 30767499 DOI: 10.1021/acs.jpclett.9b00304] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Many organic semiconductors (OSCs) feature strong optical anisotropy that can be exploited to increase the efficiency of optoelectronic devices. We demonstrate that for the technologically relevant, rod-like OSCs diindenoperylene (DIP), pentacene (PEN), and α-sexithiophene (6T) deposited on silicon oxide surfaces it is possible to prepare polycrystalline thin films in which the long molecular axis is oriented parallel to the substrate plane in a template-free fashion. In films grown by organic molecular beam deposition at room temperature or higher, the molecules are oriented upright standing (σ-orientation). Instead, the here-presented growth at low temperatures followed by slow annealing up to a temperature near molecular desorption has the effect of "freezing" the molecules with their long axis oriented parallel to the substrate plane (λ-orientation) while conferring them crystalline long-range order. We discuss the huge impact on the optical anisotropy of the films observed as a consequence of the orientation transition. Finally, we propose a mechanism for explaining the achieved λ-orientation, which is stable under environmental conditions.
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Affiliation(s)
- Giuliano Duva
- Institute for Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Alexander Mann
- Institute for Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Linus Pithan
- ESRF The European Synchrotron , 71, Avenue des Martyrs , 38000 Grenoble , France
| | - Paul Beyer
- ESRF The European Synchrotron , 71, Avenue des Martyrs , 38000 Grenoble , France
| | - Jan Hagenlocher
- Institute for Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Alexander Gerlach
- Institute for Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Alexander Hinderhofer
- Institute for Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Frank Schreiber
- Institute for Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
- Center for Light-Matter Interactions, Sensors & Analytics (LISA+) , Auf der Morgenstelle, 15 , 72076 Tübingen , Germany
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17
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Yamada K, Okamoto M, Sakurai M, Suenobu T, Nakayama KI. Solution-processable reduced graphene oxide template layer for molecular orientation control of organic semiconductors. RSC Adv 2019; 9:32940-32945. [PMID: 35529162 PMCID: PMC9073147 DOI: 10.1039/c9ra06258k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 10/09/2019] [Indexed: 01/17/2023] Open
Abstract
An ultrasmooth reduced graphene oxide (rGO) film indicated a strong templating effect inducing a face-on orientation for copper phthalocyanine.
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Affiliation(s)
- Keitaro Yamada
- Department of Material and Life Science
- Osaka University
- Suita
- Japan
| | | | - Minori Sakurai
- Department of Material and Life Science
- Osaka University
- Suita
- Japan
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18
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Navarro-Quezada A, Ghanbari E, Wagner T, Zeppenfeld P. Molecular Reorientation during the Initial Growth of Perfluoropentacene on Ag(110). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:12704-12711. [PMID: 29963216 PMCID: PMC6018566 DOI: 10.1021/acs.jpcc.8b00869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 05/28/2018] [Indexed: 05/09/2023]
Abstract
Perfluoropentacene (PFP) is an organic material that has been widely studied over the last years and has already found applications in organic electronics. However, fundamental physical questions, such as the structural formation and the preferential orientation of the molecules during deposition on metal surfaces, are still not fully understood. In this work, we report on a unique in-plane molecular reorientation during the completion of the first monolayer of PFP on the Ag(110) surface. To characterize the molecular alignment, we have monitored the deposition process in real time using polarization-dependent differential reflectance spectroscopy and reflectance anisotropy spectroscopy. Abrupt changes in the optical signals reveal an intricate sequence of reorientation transitions of the PFP molecules upon monolayer completion and during the formation of the second monolayer, eventually leading to a full alignment of the long molecular axis along the [001] direction of the substrate and an enhanced structural ordering. Scanning tunneling microscopy and low-energy electron diffraction confirm the observed molecular reorientation upon monolayer compression and provide further details on the structural and orientational ordering of the PFP monolayer before and after compression.
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Affiliation(s)
- Andrea Navarro-Quezada
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
- E-mail: (A.N.-Q)
| | - Ebrahim Ghanbari
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
| | - Thorsten Wagner
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
- E-mail: (T.W.)
| | - Peter Zeppenfeld
- Institute of Experimental Physics and Institute of Semiconductor and
Solid State Physics, Johannes Kepler University, Altenberger Street 69, 4040 Linz, Austria
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19
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Refaely-Abramson S, da Jornada FH, Louie SG, Neaton JB. Origins of Singlet Fission in Solid Pentacene from an ab initio Green's Function Approach. PHYSICAL REVIEW LETTERS 2017; 119:267401. [PMID: 29328724 DOI: 10.1103/physrevlett.119.267401] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Indexed: 05/24/2023]
Abstract
We develop a new first-principles approach to predict and understand rates of singlet fission with an ab initio Green's-function formalism based on many-body perturbation theory. Starting with singlet and triplet excitons computed from a GW plus Bethe-Salpeter equation approach, we calculate the exciton-biexciton coupling to lowest order in the Coulomb interaction, assuming a final state consisting of two noninteracting spin-correlated triplets with finite center-of-mass momentum. For crystalline pentacene, symmetries dictate that the only purely Coulombic fission decay process from a bright singlet state requires a final state consisting of two inequivalent nearly degenerate triplets of nonzero, equal and opposite, center-of-mass momenta. For such a process, we predict a singlet lifetime of 30-70 fs, in very good agreement with experimental data, indicating that this process can dominate singlet fission in crystalline pentacene. Our approach is general and provides a framework for predicting and understanding multiexciton interactions in solids.
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Affiliation(s)
- Sivan Refaely-Abramson
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Felipe H da Jornada
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Steven G Louie
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jeffrey B Neaton
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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20
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Rinn A, Breuer T, Wiegand J, Beck M, Hübner J, Döring RC, Oestreich M, Heimbrodt W, Witte G, Chatterjee S. Interfacial Molecular Packing Determines Exciton Dynamics in Molecular Heterostructures: The Case of Pentacene-Perfluoropentacene. ACS APPLIED MATERIALS & INTERFACES 2017; 9:42020-42028. [PMID: 29135216 DOI: 10.1021/acsami.7b11118] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The great majority of electronic and optoelectronic devices depend on interfaces between p-type and n-type semiconductors. Finding matching donor-acceptor systems in molecular semiconductors remains a challenging endeavor because structurally compatible molecules may not necessarily be suitable with respect to their optical and electronic properties, and the large exciton binding energy in these materials may favor bound electron-hole pairs rather than free carriers or charge transfer at an interface. Regardless, interfacial charge-transfer exciton states are commonly considered as an intermediate step to achieve exciton dissociation. The formation efficiency and decay dynamics of such states will strongly depend on the molecular makeup of the interface, especially the relative alignment of donor and acceptor molecules. Structurally well-defined pentacene-perfluoropentacene heterostructures of different molecular orientations are virtually ideal model systems to study the interrelation between molecular packing motifs at the interface and their electronic properties. Comparing the emission dynamics of the heterosystems and the corresponding unitary films enables accurate assignment of every observable emission signal in the heterosystems. These heterosystems feature two characteristic interface-specific luminescence channels at around 1.4 and 1.5 eV that are not observed in the unitary samples. Their emission strength strongly depends on the molecular alignment of the respective donor and acceptor molecules, emphasizing the importance of structural control for device construction.
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Affiliation(s)
- Andre Rinn
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Tobias Breuer
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Julia Wiegand
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Michael Beck
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Jens Hübner
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Robin C Döring
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Michael Oestreich
- Institut für Festkörperphysik, Leibniz Universität Hannover , Appelstrasse 2, D-30167 Hannover, Germany
| | - Wolfram Heimbrodt
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Gregor Witte
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
| | - Sangam Chatterjee
- Faculty of Physics & Materials Sciences Centre, Philipps-Universität Marburg , Renthof 5, 35032 Marburg, Germany
- Institute of Experimental Physics I, Justus-Liebig-University Giessen , Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
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21
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Berkelbach TC. Electronic Structure and Dynamics of Singlet Fission in Organic Molecules and Crystals. ADVANCES IN CHEMICAL PHYSICS 2017. [DOI: 10.1002/9781119324560.ch1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Affiliation(s)
- Timothy C. Berkelbach
- Department of Chemistry and The James Franck Institute; The University of Chicago; Chicago IL 60637 USA
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22
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Shioya N, Shimoaka T, Murdey R, Hasegawa T. Accurate Molecular Orientation Analysis Using Infrared p-Polarized Multiple-Angle Incidence Resolution Spectrometry (pMAIRS) Considering the Refractive Index of the Thin Film Sample. APPLIED SPECTROSCOPY 2017; 71:1242-1248. [PMID: 28534674 DOI: 10.1177/0003702816676492] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Infrared (IR) p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) is a powerful tool for analyzing the molecular orientation in an organic thin film. In particular, pMAIRS works powerfully for a thin film with a highly rough surface irrespective of degree of the crystallinity. Recently, the optimal experimental condition has comprehensively been revealed, with which the accuracy of the analytical results has largely been improved. Regardless, some unresolved matters still remain. A structurally isotropic sample, for example, yields different peak intensities in the in-plane and out-of-plane spectra. In the present study, this effect is shown to be due to the refractive index of the sample film and a correction factor has been developed using rigorous theoretical methods. As a result, with the use of the correction factor, organic materials having atypical refractive indices such as perfluoroalkyl compounds ( n = 1.35) and fullerene ( n = 1.83) can be analyzed with high accuracy comparable to a compound having a normal refractive index of approximately 1.55. With this improved technique, we are also ready for discriminating an isotropic structure from an oriented sample having the magic angle of 54.7°.
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Affiliation(s)
- Nobutaka Shioya
- 1 Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Kyoto, Japan
| | - Takafumi Shimoaka
- 1 Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Kyoto, Japan
| | - Richard Murdey
- 2 Laboratory of Molecular Aggregation Analysis, Division of Multidisciplinary Chemistry, Institute for Chemical Research, Kyoto University, Kyoto, Japan
| | - Takeshi Hasegawa
- 1 Laboratory of Solution and Interface Chemistry, Division of Environmental Chemistry, Institute for Chemical Research, Kyoto University, Kyoto, Japan
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23
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Breuer T, Klues M, Liesfeld P, Viertel A, Conrad M, Hecht S, Witte G. Self-assembly of partially fluorinated hexabenzocoronene derivatives in the solid state. Phys Chem Chem Phys 2016; 18:33344-33350. [DOI: 10.1039/c6cp06126e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We provide a detailed understanding on a successful route to control the molecular packing motif within novel fluorinated hexabenzocoronenes.
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Affiliation(s)
- Tobias Breuer
- Fachbereich Physik
- Universität Marburg
- 35032 Marburg
- Germany
| | - Michael Klues
- Fachbereich Physik
- Universität Marburg
- 35032 Marburg
- Germany
| | - Pauline Liesfeld
- Department of Chemistry
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | - Andreas Viertel
- Department of Chemistry
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | | | - Stefan Hecht
- Department of Chemistry
- Humboldt-Universität zu Berlin
- 12489 Berlin
- Germany
| | - Gregor Witte
- Fachbereich Physik
- Universität Marburg
- 35032 Marburg
- Germany
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24
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Black HT, Pelse I, Wolfe RMW, Reynolds JR. Halochromism and protonation-induced assembly of a benzo[g]indolo[2,3-b]quinoxaline derivative. Chem Commun (Camb) 2016; 52:12877-12880. [DOI: 10.1039/c6cc06443d] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new halochromic compound is reported with pronounced UV/Vis spectral responses that depend on the extent of protonation and on the counter-ion structure.
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Affiliation(s)
- Hayden T. Black
- School of Chemistry and Biochemistry and School of Materials Science and Engineering
- Center for Organic Photonics and Electronics
- Georgia Tech Polymer Network
- Georgia Institute of Technology
- Atlanta
| | - Ian Pelse
- School of Chemistry and Biochemistry and School of Materials Science and Engineering
- Center for Organic Photonics and Electronics
- Georgia Tech Polymer Network
- Georgia Institute of Technology
- Atlanta
| | - Rylan M. W. Wolfe
- School of Chemistry and Biochemistry and School of Materials Science and Engineering
- Center for Organic Photonics and Electronics
- Georgia Tech Polymer Network
- Georgia Institute of Technology
- Atlanta
| | - John R. Reynolds
- School of Chemistry and Biochemistry and School of Materials Science and Engineering
- Center for Organic Photonics and Electronics
- Georgia Tech Polymer Network
- Georgia Institute of Technology
- Atlanta
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25
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Wang X, Garcia T, Monaco S, Schatschneider B, Marom N. Effect of crystal packing on the excitonic properties of rubrene polymorphs. CrystEngComm 2016. [DOI: 10.1039/c6ce00873a] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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26
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Wang X, Broch K, Schreiber F, Meixner AJ, Zhang D. Revealing nanoscale optical properties and morphology in perfluoropentacene films by confocal and tip-enhanced near-field optical microscopy and spectroscopy. Phys Chem Chem Phys 2016; 18:15919-26. [DOI: 10.1039/c6cp01153e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Combining confocal and high resolution near-field optical microscopy and spectroscopy, we propose a sensitive method for determining the local morphology in organic semiconductor thin films.
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Affiliation(s)
- Xiao Wang
- Institute of Physical and Theoretical Chemistry and LISA+
- University of Tübingen
- 72076 Tübingen
- Germany
| | - Katharina Broch
- Institute of Applied Physics
- University of Tübingen
- 72076 Tübingen
- Germany
- Cavendish Laboratory
| | - Frank Schreiber
- Institute of Applied Physics
- University of Tübingen
- 72076 Tübingen
- Germany
| | - Alfred J. Meixner
- Institute of Physical and Theoretical Chemistry and LISA+
- University of Tübingen
- 72076 Tübingen
- Germany
| | - Dai Zhang
- Institute of Physical and Theoretical Chemistry and LISA+
- University of Tübingen
- 72076 Tübingen
- Germany
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27
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Meyenburg I, Breuer T, Karthäuser A, Chatterjee S, Witte G, Heimbrodt W. Temperature-resolved optical spectroscopy of pentacene polymorphs: variation of herringbone angles in single-crystals and interface-controlled thin films. Phys Chem Chem Phys 2016; 18:3825-31. [DOI: 10.1039/c5cp07836a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An interrelation between the Davydov splitted singlet-exciton and the temperature dependent herringbone angle in crystalline pentacene films is shown.
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Affiliation(s)
- Ingo Meyenburg
- Philipps-University Marburg
- Department of Physics and Material Sciences Center
- D-35032 Marburg
- Germany
| | - Tobias Breuer
- Philipps-University Marburg
- Department of Physics and Material Sciences Center
- D-35032 Marburg
- Germany
| | - Andrea Karthäuser
- Philipps-University Marburg
- Department of Physics and Material Sciences Center
- D-35032 Marburg
- Germany
| | - Sangam Chatterjee
- Philipps-University Marburg
- Department of Physics and Material Sciences Center
- D-35032 Marburg
- Germany
| | - Gregor Witte
- Philipps-University Marburg
- Department of Physics and Material Sciences Center
- D-35032 Marburg
- Germany
| | - Wolfram Heimbrodt
- Philipps-University Marburg
- Department of Physics and Material Sciences Center
- D-35032 Marburg
- Germany
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28
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Navarro-Quezada A, Aiglinger M, Ghanbari E, Wagner T, Zeppenfeld P. Polarization-dependent differential reflectance spectroscopy for real-time monitoring of organic thin film growth. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2015; 86:113108. [PMID: 26628122 DOI: 10.1063/1.4936352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
By monitoring the reflectance of a sample surface during deposition of a thin organic film, one can obtain information with submonolayer resolution in real-time. A special kind of optical spectroscopy is Differential Reflectance Spectroscopy (DRS), which compares the reflectance before and during deposition of a thin film or any other change of the surface optical properties. In this work, we present an extended DRS setup that allows monitoring simultaneously both linear polarization states (s and p) of the reflected light. We implement polarization-dependent DRS to monitor the growth of perflouropentacene thin films on a Ag(110) single crystal. The setup allows us to deduce the optical anisotropy of the sample and, in particular, the preferred orientation of the molecules on the surface.
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Affiliation(s)
- A Navarro-Quezada
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - M Aiglinger
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - E Ghanbari
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - Th Wagner
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
| | - P Zeppenfeld
- Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz, Austria
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29
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Jo SB, Kim HH, Lee H, Kang B, Lee S, Sim M, Kim M, Lee WH, Cho K. Boosting Photon Harvesting in Organic Solar Cells with Highly Oriented Molecular Crystals via Graphene-Organic Heterointerface. ACS NANO 2015; 9:8206-19. [PMID: 26166186 DOI: 10.1021/acsnano.5b03929] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Photon harvesting in organic solar cells is highly dependent on the anisotropic nature of the optoelectronic properties of photoactive materials. Here, we demonstrate an efficient approach to dramatically enhance photon harvesting in planar heterojunction solar cells by using a graphene-organic heterointerface. A large area, residue-free monolayer graphene is inserted at anode interface to serve as an atomically thin epitaxial template for growing highly orientated pentacene crystals with lying-down orientation. This anisotropic orientation enhances the overall optoelectronic properties, including light absorption, charge carrier lifetime, interfacial energetics, and especially the exciton diffusion length. Spectroscopic and crystallographic analysis reveal that the lying-down orientation persists until a thickness of 110 nm, which, along with increased exciton diffusion length up to nearly 100 nm, allows the device optimum thickness to be doubled to yield significantly enhanced light absorption within the photoactive layers. The resultant photovoltaic performance shows simultaneous increment in Voc, Jsc, and FF, and consequently a 5 times increment in the maximum power conversion efficiency than the equivalent devices without a graphene layer. The present findings indicate that controlling organic-graphene heterointerface could provide a design strategy of organic solar cell architecture for boosting photon harvesting.
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Affiliation(s)
- Sae Byeok Jo
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Hyun Ho Kim
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Hansol Lee
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Boseok Kang
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Seongkyu Lee
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Myungsun Sim
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Min Kim
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
| | - Wi Hyoung Lee
- Department of Organic and Nano System Engineering, Konkuk University , Seoul 143-701, Korea
| | - Kilwon Cho
- Department of Chemical Engineering, Pohang University of Science and Technology , Pohang 790-784, Korea
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30
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Schwaben J, Münster N, Klues M, Breuer T, Hofmann P, Harms K, Witte G, Koert U. Efficient Syntheses of Novel Fluoro-Substituted Pentacenes and Azapentacenes: Molecular and Solid-State Properties. Chemistry 2015; 21:13758-71. [DOI: 10.1002/chem.201501399] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Indexed: 11/11/2022]
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31
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Anger F, Scholz R, Gerlach A, Schreiber F. Vibrational modes and changing molecular conformation of perfluororubrene in thin films and solution. J Chem Phys 2015; 142:224703. [DOI: 10.1063/1.4922052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- F. Anger
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - R. Scholz
- Institut für Angewandte Photophysik, TU Dresden, 01069 Dresden, Germany
| | - A. Gerlach
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
| | - F. Schreiber
- Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen, Germany
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32
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Kolata K, Breuer T, Witte G, Chatterjee S. Molecular packing determines singlet exciton fission in organic semiconductors. ACS NANO 2014; 8:7377-83. [PMID: 24957197 DOI: 10.1021/nn502544d] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Carrier multiplication by singlet exciton fission enhances photovoltaic conversion efficiencies in organic solids. This decay of one singlet exciton into two triplet states allows the extraction of up to two electrons per harvested photon and, hence, promises to overcome the Shockley–Queisser limit. However, the microscopic mechanism of singlet exciton fission, especially the relation between molecular packing and electronic response, remains unclear, which therefore hampers the systematic improvement of organic photovoltaic devices. For the model system perfluoropentacene, we experimentally show that singlet exciton fission is greatly enhanced for a slip-stacked molecular arrangement by addressing different crystal axes featuring different packing schemes. This reveals that the fission process strongly depends on the intermolecular coupling: slip-stacking favors delocalization of excitations and allows for efficient exciton fission, while face-to-edge molecular orientations commonly found in the prevailing herringbone molecular stacking patterns even suppress it. Furthermore, we clarify the controversially debated role of excimer states as intermediary rather than competitive or precursory. Our detailed findings serve as a guideline for the design of next-generation molecular materials for application in future organic light-harvesting devices exploiting singlet exciton fission.
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33
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Wang X, Broch K, Scholz R, Schreiber F, Meixner AJ, Zhang D. Topography-Correlated Confocal Raman Microscopy with Cylindrical Vector Beams for Probing Nanoscale Structural Order. J Phys Chem Lett 2014; 5:1048-1054. [PMID: 26274447 DOI: 10.1021/jz500061y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Cylindrical vector beams, such as radially or azimuthally polarized doughnut beams, are combined with topography studies of pentacene thin films, allowing us to correlate Raman spectroscopy with intermolecular interactions depending on the particular pentacene polymorph. Polarization-dependent Raman spectra of the C-H bending vibrations are resolved layer by layer within a thin film of ∼20 nm thickness. The variation of the Raman peak positions indicates changes in the molecular orientation and in the local environment at different heights of the pentacene film. With the assistance of a theoretical model based on harmonic oscillator and perturbation theory, our method reveals the local structural order and the polymorph at different locations within the same pentacene thin film, depending mainly on its thickness. In good agreement with the crystallographic structures reported in the literature, our observations demonstrate that the first few monolayers grown in a structure are closer to the thin-film phase, but for larger film thicknesses, the morphology evolves toward the crystal-bulk phase with a larger tilting angle of the pentacene molecules against the substrate normal.
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Affiliation(s)
- Xiao Wang
- †Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Katharina Broch
- ‡Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Reinhard Scholz
- §Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden, Germany
| | - Frank Schreiber
- ‡Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Alfred J Meixner
- †Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Dai Zhang
- †Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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34
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Structure and optical bandgap relationship of π-conjugated systems. PLoS One 2014; 9:e86370. [PMID: 24497944 PMCID: PMC3908919 DOI: 10.1371/journal.pone.0086370] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/06/2013] [Indexed: 11/19/2022] Open
Abstract
In bulk heterojunction photovoltaic systems both the open-circuit voltage as well as the short-circuit current, and hence the power conversion efficiency, are dependent on the optical bandgap of the electron-donor material. While first-principles methods are computationally intensive, simpler model Hamiltonian approaches typically suffer from one or more flaws: inability to optimize the geometries for their own input; absence of general, transferable parameters; and poor performance for non-planar systems. We introduce a set of new and revised parameters for the adapted Su-Schrieffer-Heeger (aSSH) Hamiltonian, which is capable of optimizing geometries, along with rules for applying them to any [Formula: see text]-conjugated system containing C, N, O, or S, including non-planar systems. The predicted optical bandgaps show excellent agreement to UV-vis spectroscopy data points from literature, with a coefficient of determination [Formula: see text], a mean error of -0.05 eV, and a mean absolute deviation of 0.16 eV. We use the model to gain insights from PEDOT, fused thiophene polymers, poly-isothianaphthene, copolymers, and pentacene as sources of design rules in the search for low bandgap materials. Using the model as an in-silico design tool, a copolymer of benzodithiophenes along with a small-molecule derivative of pentacene are proposed as optimal donor materials for organic photovoltaics.
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35
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Horrer A, Schäfer C, Broch K, Gollmer DA, Rogalski J, Fulmes J, Zhang D, Meixner AJ, Schreiber F, Kern DP, Fleischer M. Parallel fabrication of plasmonic nanocone sensing arrays. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:3987-4088. [PMID: 24302595 DOI: 10.1002/smll.201300449] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Indexed: 06/02/2023]
Abstract
A fully parallel approach for the fabrication of arrays of metallic nanocones and triangular nanopyramids is presented. Different processes utilizing nanosphere lithography for the creation of etch masks are developed. Monolayers of spheres are reduced in size and directly used as masks, or mono- and double layers are employed as templates for the deposition of aluminum oxide masks. The masks are transferred into an underlying gold or silver layer by argon ion milling, which leads to nanocones or nanopyramids with very sharp tips. Near the tips the enhancement of an external electromagnetic field is particularly strong. This fact is confirmed by numerical simulations and by luminescence imaging in a confocal microscope. Such localized strong fields can amongst others be utilized for high-resolution, high-sensitivity spectroscopy and sensing of molecules near the tip. Arrays of such plasmonic nanostructures thus constitute controllable platforms for surface-enhanced Raman spectroscopy. A thin film of pentacene molecules is evaporated onto both nanocone and nanopyramid substrates, and the observed Raman enhancement is evaluated.
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Affiliation(s)
- Andreas Horrer
- Institute for Applied Physics and Center LISA[+], Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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36
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Broch K, Gerlach A, Lorch C, Dieterle J, Novák J, Hinderhofer A, Schreiber F. Structure formation in perfluoropentacene:diindenoperylene blends and its impact on transient effects in the optical properties studied in real-time during growth. J Chem Phys 2013; 139:174709. [PMID: 24206324 DOI: 10.1063/1.4827868] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- K Broch
- Universität Tübingen, Institut für Angewandte Physik and LISA+, Auf der Morgenstelle 10, 72076 Tübingen, Germany
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37
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Influence of substitution on the optical properties of functionalized pentacene monomers and crystals: Experiment and theory. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.08.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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38
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Breuer T, Witte G. Thermally activated intermixture in pentacene-perfluoropentacene heterostructures. J Chem Phys 2013; 138:114901. [DOI: 10.1063/1.4795004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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39
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Schwaben J, Münster N, Breuer T, Klues M, Harms K, Witte G, Koert U. Synthesis and Solid-State Structures of 6,13-Bis(trifluoromethyl)- and 6,13-Dialkoxypentacene. European J Org Chem 2013. [DOI: 10.1002/ejoc.201201714] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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40
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In situ structural characterization of picene thin films by X-ray scattering: Vacuum versus O2 atmosphere. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.07.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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41
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Hinderhofer A, Frank C, Hosokai T, Resta A, Gerlach A, Schreiber F. Structure and morphology of coevaporated pentacene-perfluoropentacene thin films. J Chem Phys 2012; 134:104702. [PMID: 21405179 DOI: 10.1063/1.3557476] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structural properties of coevaporated thin films of pentacene (PEN) and perfluoropentacene (PFP) on SiO(2) were studied using x-ray reflectivity and grazing incidence x-ray diffraction. Reciprocal space maps of the coevaporated thin films with different volume fractions reveal the coexistence of two different molecular mixed PEN-PFP phases together with the pure PEN and PFP crystallites. The crystal structure of PEN:PFP blends does not change continuously with volume fraction, instead the proportion of the appropriate phases changes, as seen from the diffraction analysis. Additional temperature dependent experiments reveal that the fraction of the two mixed PEN-PFP phases varies with growth temperature. The λ-phase (molecular plane parallel to the substrate) is metastable and induced by low growth temperature. The σ-phase (molecular plane nearly perpendicular to the substrate) is thermally stable and nucleates predominantly at high growth temperatures.
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Affiliation(s)
- A Hinderhofer
- Institut für Angewandte Physik, Universität Tübingen, Tübingen, Germany
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42
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Anger F, Ossó JO, Heinemeyer U, Broch K, Scholz R, Gerlach A, Schreiber F. Photoluminescence spectroscopy of pure pentacene, perfluoropentacene, and mixed thin films. J Chem Phys 2012; 136:054701. [DOI: 10.1063/1.3677839] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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43
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Forker R, Gruenewald M, Fritz T. Optical differential reflectance spectroscopy on thin molecular films. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2pc90002e] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Botelho AL, Shin Y, Li M, Jiang L, Lin X. Unified Hamiltonian for conducting polymers. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:455501. [PMID: 22021333 DOI: 10.1088/0953-8984/23/45/455501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Two transferable physical parameters are incorporated into the Su-Schrieffer-Heeger Hamiltonian to model conducting polymers beyond polyacetylene: the parameter γ scales the electron-phonon coupling strength in aromatic rings and the other parameter ε specifies the heterogeneous core charges. This generic Hamiltonian predicts the fundamental band gaps of polythiophene, polypyrrole, polyfuran, poly-(p-phenylene), poly-(p-phenylene vinylene), and polyacenes, and their oligomers of all lengths, with an accuracy exceeding time-dependent density functional theory. Its computational costs for moderate-length polymer chains are more than eight orders of magnitude lower than first-principles approaches.
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Affiliation(s)
- André Leitão Botelho
- Department of Mechanical Engineering and Division of Materials Science and Engineering, Boston University, Boston, MA 02215, USA
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45
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Ha SD, Qi Y, Kahn A. Relative permittivity and Hubbard U of pentacene extracted from scanning tunneling microscopy studies of p-doped films. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2010.06.085] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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Heinemeyer U, Broch K, Hinderhofer A, Kytka M, Scholz R, Gerlach A, Schreiber F. Real-time changes in the optical spectrum of organic semiconducting films and their thickness regimes during growth. PHYSICAL REVIEW LETTERS 2010; 104:257401. [PMID: 20867413 DOI: 10.1103/physrevlett.104.257401] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Indexed: 05/13/2023]
Abstract
We present real-time in situ studies of optical spectra during thin film growth of several prototype organic semiconductors (pentacene, perfluoropentacene, and diindenoperylene) on SiO2. These data provide insight into surface and interface effects that are of fundamental importance and of relevance for applications in organic electronics. With respect to the bulk, the different molecular environment and structural changes within the first few monolayers can give rise to significant optical changes. Similar to interface-driven phenomena in, e.g., magnetism, spectral changes as a function of thickness d are a very general effect, decaying as 1/d in the simplest approximation. We observe energy shifts of 50-100 meV, rather small changes of the exciton-phonon coupling, and new transitions in specific systems, which should be considered as general features of the growth of organics.
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Affiliation(s)
- U Heinemeyer
- Institut für Angewandte Physik, Uni Tübingen, 72076 Tübingen, Germany
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47
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Amassian A, Pozdin VA, Li R, Smilgies DM, Malliaras GG. Solvent vapor annealing of an insoluble molecular semiconductor. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b923375j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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48
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Mondal R, Tönshoff C, Khon D, Neckers DC, Bettinger HF. Synthesis, Stability, and Photochemistry of Pentacene, Hexacene, and Heptacene: A Matrix Isolation Study. J Am Chem Soc 2009; 131:14281-9. [DOI: 10.1021/ja901841c] [Citation(s) in RCA: 192] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rajib Mondal
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, and Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Christina Tönshoff
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, and Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Dmitriy Khon
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, and Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Douglas C. Neckers
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, and Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Holger F. Bettinger
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, and Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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49
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Kytka M, Gisslen L, Gerlach A, Heinemeyer U, Kováč J, Scholz R, Schreiber F. Optical spectra obtained from amorphous films of rubrene: Evidence for predominance of twisted isomer. J Chem Phys 2009; 130:214507. [DOI: 10.1063/1.3147009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Forker R, Fritz T. Optical differential reflectance spectroscopy of ultrathin epitaxial organic films. Phys Chem Chem Phys 2009; 11:2142-55. [PMID: 19305886 DOI: 10.1039/b814628d] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This Perspective does not have the ambition to entirely review the subject of optical spectroscopy on thin organic films. What we will try to achieve instead is to give an overview on optical reflectance spectroscopy of highly ordered organic thin films in the thickness range from submonolayers to several monolayers, as a tool to study the absorption behavior of such films. By doing so, we will emphasize the relations between the physical layer structure and the resulting optical properties. More specifically, we intend to show on the basis of particular examples what physical effects can be favorably examined by means of real-time optical spectroscopy, i.e., applied during the actual film growth, especially differential reflectance spectroscopy (DRS). Epitaxial organic films on inorganic substrates (insulators and conductors) will be in focus, and also the perspectives of investigating organic-organic heteroepitaxial layers will be addressed.
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Affiliation(s)
- Roman Forker
- Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany
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