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Masters RC, Stehling N, Abrams KJ, Kumar V, Azzolini M, Pugno NM, Dapor M, Huber A, Schäfer P, Lidzey DG, Rodenburg C. Mapping Polymer Molecular Order in the SEM with Secondary Electron Hyperspectral Imaging. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1801752. [PMID: 30886802 PMCID: PMC6402282 DOI: 10.1002/advs.201801752] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/08/2018] [Indexed: 05/03/2023]
Abstract
Understanding nanoscale molecular order within organic electronic materials is a crucial factor in building better organic electronic devices. At present, techniques capable of imaging molecular order within a polymer are limited in resolution, accuracy, and accessibility. In this work, presented are secondary electron (SE) spectroscopy and secondary electron hyperspectral imaging, which make an exciting alternative approach to probing molecular ordering in poly(3-hexylthiophene) (P3HT) with scanning electron microscope-enabled resolution. It is demonstrated that the crystalline content of a P3HT film is reflected by its SE energy spectrum, both empirically and through correlation with nano-Fourier-transform infrared spectroscopy, an innovative technique for exploring nanoscale chemistry. The origin of SE spectral features is investigated using both experimental and modeling approaches, and it is found that the different electronic properties of amorphous and crystalline P3HT result in SE emission with different energy distributions. This effect is exploited by acquiring hyperspectral SE images of different P3HT films to explore localized molecular orientation. Machine learning techniques are used to accurately identify and map the crystalline content of the film, demonstrating the power of an exciting characterization technique.
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Affiliation(s)
- Robert C. Masters
- Department of Materials Science and EngineeringUniversity of SheffieldSheffieldS1 3JDUK
| | - Nicola Stehling
- Department of Materials Science and EngineeringUniversity of SheffieldSheffieldS1 3JDUK
| | - Kerry J. Abrams
- Department of Materials Science and EngineeringUniversity of SheffieldSheffieldS1 3JDUK
| | - Vikas Kumar
- Department of Materials Science and EngineeringUniversity of SheffieldSheffieldS1 3JDUK
| | - Martina Azzolini
- European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*‐FBK) and Trento Institute for Fundamental Physics and Applications (TIFPA‐INFN)Trento38123Italy
- Laboratory of Bio‐Inspired and Graphene NanomechanicsDepartment of CivilEnvironmental and Mechanical EngineeringUniversity of TrentoTrento38123Italy
| | - Nicola M. Pugno
- Laboratory of Bio‐Inspired and Graphene NanomechanicsDepartment of CivilEnvironmental and Mechanical EngineeringUniversity of TrentoTrento38123Italy
- Ket‐LabEdoardo Amaldi FoundationRome00133Italy
- School of Engineering and Materials ScienceQueen Mary University of LondonLondonE1 4NSUK
| | - Maurizio Dapor
- European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*‐FBK) and Trento Institute for Fundamental Physics and Applications (TIFPA‐INFN)Trento38123Italy
| | | | | | - David G. Lidzey
- Department of Physics and AstronomyUniversity of SheffieldSheffieldS3 7RHUK
| | - Cornelia Rodenburg
- Department of Materials Science and EngineeringUniversity of SheffieldSheffieldS1 3JDUK
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Leijten ZJA, Keizer ADA, de With G, Friedrich H. Quantitative Analysis of Electron Beam Damage in Organic Thin Films. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:10552-10561. [PMID: 28553431 PMCID: PMC5442601 DOI: 10.1021/acs.jpcc.7b01749] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/21/2017] [Indexed: 05/09/2023]
Abstract
In transmission electron microscopy (TEM) the interaction of an electron beam with polymers such as P3HT:PCBM photovoltaic nanocomposites results in electron beam damage, which is the most important factor limiting acquisition of structural or chemical data at high spatial resolution. Beam effects can vary depending on parameters such as electron dose rate, temperature during imaging, and the presence of water and oxygen in the sample. Furthermore, beam damage will occur at different length scales. To assess beam damage at the angstrom scale, we followed the intensity of P3HT and PCBM diffraction rings as a function of accumulated electron dose by acquiring dose series and varying the electron dose rate, sample preparation, and the temperature during acquisition. From this, we calculated a critical dose for diffraction experiments. In imaging mode, thin film deformation was assessed using the normalized cross-correlation coefficient, while mass loss was determined via changes in average intensity and standard deviation, also varying electron dose rate, sample preparation, and temperature during acquisition. The understanding of beam damage and the determination of critical electron doses provides a framework for future experiments to maximize the information content during the acquisition of images and diffraction patterns with (cryogenic) transmission electron microscopy.
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Affiliation(s)
- Zino J.
W. A. Leijten
- Laboratory
of Materials and Interface Chemistry, Department of Chemical
Engineering and Chemistry, and Centre for Multiscale Electron Microscopy, Eindhoven University of Technology, Het Kranenveld 14, Postbus 513-5600 MB, Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, De Zaale, 5612 AJ Eindhoven, The Netherlands
| | - Arthur D. A. Keizer
- Laboratory
of Materials and Interface Chemistry, Department of Chemical
Engineering and Chemistry, and Centre for Multiscale Electron Microscopy, Eindhoven University of Technology, Het Kranenveld 14, Postbus 513-5600 MB, Eindhoven, The Netherlands
| | - Gijsbertus de With
- Laboratory
of Materials and Interface Chemistry, Department of Chemical
Engineering and Chemistry, and Centre for Multiscale Electron Microscopy, Eindhoven University of Technology, Het Kranenveld 14, Postbus 513-5600 MB, Eindhoven, The Netherlands
| | - Heiner Friedrich
- Laboratory
of Materials and Interface Chemistry, Department of Chemical
Engineering and Chemistry, and Centre for Multiscale Electron Microscopy, Eindhoven University of Technology, Het Kranenveld 14, Postbus 513-5600 MB, Eindhoven, The Netherlands
- Institute
for Complex Molecular Systems, Eindhoven
University of Technology, De Zaale, 5612 AJ Eindhoven, The Netherlands
- E-mail ; phone +31 (0)40 247 3041 (H.F.)
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Giridharagopal R, Cox PA, Ginger DS. Functional Scanning Probe Imaging of Nanostructured Solar Energy Materials. Acc Chem Res 2016; 49:1769-76. [PMID: 27575611 DOI: 10.1021/acs.accounts.6b00255] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
From hybrid perovskites to semiconducting polymer/fullerene blends for organic photovoltaics, many new materials being explored for energy harvesting and storage exhibit performance characteristics that depend sensitively on their nanoscale morphology. At the same time, rapid advances in the capability and accessibility of scanning probe microscopy methods over the past decade have made it possible to study processing/structure/function relationships ranging from photocurrent collection to photocarrier lifetimes with resolutions on the scale of tens of nanometers or better. Importantly, such scanning probe methods offer the potential to combine measurements of local structure with local function, and they can be implemented to study materials in situ or devices in operando to better understand how materials evolve in time in response to an external stimulus or environmental perturbation. This Account highlights recent advances in the development and application of scanning probe microscopy methods that can help address such questions while filling key gaps between the capabilities of conventional electron microscopy and newer super-resolution optical methods. Focusing on semiconductor materials for solar energy applications, we highlight a range of electrical and optoelectronic scanning probe microscopy methods that exploit the local dynamics of an atomic force microscope tip to probe key properties of the solar cell material or device structure. We discuss how it is possible to extract relevant device properties using noncontact scanning probe methods as well as how these properties guide materials development. Specifically, we discuss intensity-modulated scanning Kelvin probe microscopy (IM-SKPM), time-resolved electrostatic force microscopy (trEFM), frequency-modulated electrostatic force microscopy (FM-EFM), and cantilever ringdown imaging. We explain these developments in the context of classic atomic force microscopy (AFM) methods that exploit the physics of cantilever motion and photocarrier generation to provide robust, nanoscale measurements of materials physics that are correlated with device operation. We predict that the multidimensional data sets made possible by these types of methods will become increasingly important as advances in data science expand capabilities and opportunities for image correlation and discovery.
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Affiliation(s)
- Rajiv Giridharagopal
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Phillip A. Cox
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - David S. Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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Kim JJ, Ha JM, Lee HM, Raza HS, Park JW, Cho SO. Effect of Electron-Beam Irradiation on Organic Semiconductor and Its Application for Transistor-Based Dosimeters. ACS APPLIED MATERIALS & INTERFACES 2016; 8:19192-19196. [PMID: 27399874 DOI: 10.1021/acsami.6b05555] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The effects of electron-beam irradiation on the organic semiconductor rubrene and its application as a dosimeter was investigated. Through the measurements of photoluminescence and the ultraviolet photoelectron spectroscopy, we found that electron-beam irradiation induces n-doping of rubrene. Additionally, we fabricated rubrene thin-film transistors with pristine and irradiated rubrene, and discovered that the decrease in transistor properties originated from the irradiation of rubrene and that the threshold voltages are shifted to the opposite directions as the irradiated layers. Finally, a highly sensitive and air-stable electron dosimeter was fabricated based on a rubrene transistor.
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Affiliation(s)
- Jae Joon Kim
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
| | - Jun Mok Ha
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
| | - Hyeok Moo Lee
- Department of Informative Electronic Materials, LG Chemistry Research Park , Daejeon 305-738, Republic of Korea
| | - Hamid Saeed Raza
- Safety Analysis Center (SAC), Pakistan Nuclear Regulatory Authority 42-C , 24th Commercial Street, Phase-II Ext., DHA, Karachi 75500, Pakistan
| | - Ji Won Park
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
| | - Sung Oh Cho
- Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
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Masters RC, Pearson AJ, Glen TS, Sasam FC, Li L, Dapor M, Donald AM, Lidzey DG, Rodenburg C. Sub-nanometre resolution imaging of polymer-fullerene photovoltaic blends using energy-filtered scanning electron microscopy. Nat Commun 2015; 6:6928. [PMID: 25906738 PMCID: PMC4423221 DOI: 10.1038/ncomms7928] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 03/16/2015] [Indexed: 12/02/2022] Open
Abstract
The resolution capability of the scanning electron microscope has increased immensely in recent years, and is now within the sub-nanometre range, at least for inorganic materials. An equivalent advance has not yet been achieved for imaging the morphologies of nanostructured organic materials, such as organic photovoltaic blends. Here we show that energy-selective secondary electron detection can be used to obtain high-contrast, material-specific images of an organic photovoltaic blend. We also find that we can differentiate mixed phases from pure material phases in our data. The lateral resolution demonstrated is twice that previously reported from secondary electron imaging. Our results suggest that our energy-filtered scanning electron microscopy approach will be able to make major inroads into the understanding of complex, nano-structured organic materials. Morphological characterization of organic photovoltaic active layers is restricted by the lack of accurate chemical mapping tools. Here, the authors demonstrate an energy-filtered scanning electron microscopy technique, which enables sub-nanometre resolution imaging of an organic photovoltaic blend.
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Affiliation(s)
- Robert C Masters
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK
| | - Andrew J Pearson
- Department of Physics, University of Cambridge, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Tom S Glen
- Department of Physics, University of Cambridge, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - Fabian-Cyril Sasam
- FEI Co. Europe NanoPort, Achtseweg Noord 5, Eindhoven, 5651 GG, The Netherlands
| | - Letian Li
- FEI Co. Europe NanoPort, Achtseweg Noord 5, Eindhoven, 5651 GG, The Netherlands
| | - Maurizio Dapor
- European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-FBK) and Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), via Sommarive 18, Trento I-38123, Italy
| | - Athene M Donald
- Department of Physics, University of Cambridge, Cavendish Laboratory, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
| | - David G Lidzey
- Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK
| | - Cornelia Rodenburg
- Department of Materials Science and Engineering, University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield S1 3JD, UK
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Sezen M, Plank H, Fisslthaler E, Chernev B, Zankel A, Tchernychova E, Blümel A, List EJW, Grogger W, Pölt P. An investigation on focused electron/ion beam induced degradation mechanisms of conjugated polymers. Phys Chem Chem Phys 2011; 13:20235-40. [DOI: 10.1039/c1cp22406a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bebensee F, Zhu J, Baricuatro JH, Farmer JA, Bai Y, Steinrück HP, Campbell CT, Gottfried JM. Interface formation between calcium and electron-irradiated poly(3-hexylthiophene). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:9632-9639. [PMID: 20334405 DOI: 10.1021/la100209v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The adsorption of Ca on electron-irradiated poly(3-hexylthiophene) (P3HT) surfaces at 300 K (E(kin) = 100 eV) has been studied by adsorption microcalorimetry, atomic beam/surface scattering, X-ray photoelectron spectroscopy (XPS), and low-energy He(+) ion scattering spectroscopy (LEIS). The results are compared to previous studies of Ca adsorption on pristine P3HT. The major structural effect of electron irradiation is a substantial increase in the fraction of unsaturated carbon atoms, probably a result of electron-induced hydrogen abstraction from the hexyl chains and formation of new C=C double bonds. No loss of sulfur was observed. The combined XPS, LEIS, and calorimetry data indicate that the reaction and growth behavior of Ca on P3HT surfaces is not significantly affected by this electron damage, apart from an increased sticking probability at low coverages. The sticking probability of Ca on the irradiated P3HT is initially 0.63, compared to 0.36 on the pristine surface. It increases with coverage, approaching unity between 4 and 5 ML. The heat of adsorption stays nearly constant at 405 kJ/mol up to a coverage of 0.6 ML, which is ascribed to Ca diffusing below the surface and forming CaS clusters by abstraction of sulfur from the thiophene rings, based on XPS and LEIS data. The heat of adsorption then decreases gradually until it reaches the heat of sublimation of bulk Ca, 178 kJ/mol, by 4 ML; this is attributed to the formation of 3D Ca islands on top of the polymer, which eventually coalesce into a continuous Ca film by 11 ML. The heat of reaction versus coverage and the ultimate depth up to which the Ca atoms react with the polymer thiophene groups (approximately 3 nm) are nearly independent of electron damage, except for a difference in the heat of adsorption below 0.1 ML associated with defects or impurities. The increase in initial sticking probability caused by electron damage is attributed to stronger bonding of Ca adatoms to unsaturated versus saturated hydrocarbons. These very weakly held Ca adatoms are transient precursors to the two reactions which dominate the measured heat of adsorption (reaction with thiophene units and Ca cluster formation), but they can also desorb in this three-path kinetic competition. Mass spectrometer data show that these precursors have longer surface residence times on the electron-damaged surface.
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Affiliation(s)
- Fabian Bebensee
- Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials, Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
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Kim H. Band-gap modification in a nanoscale region of polyethylene by fast electrons. Chemphyschem 2009; 10:442-7. [PMID: 19115324 DOI: 10.1002/cphc.200800618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Drastic change: A nanoscale spot of polyethylene (PE) can change its electrical properties dramatically after exposure to fast electrons-from a representative insulator, via a semiconductor, to a hopping conductor (see picture). These modifications of the chemical and energy-band structures of PE are extremely localized, thus opening a new way to use this conventional polymer in nanotechnology. Herein, a nanoscale area on a polyethylene film is investigated by an electron-microscope-electron-spectroscopy system after exposure to various doses of fast electrons. Therefore, modifications in its physical and chemical properties and the spatial size of a beam-affected area are measured. The results show that the modifications of PE by electrons are significant enough to rebuild the chemical and energy-band structures. Hydrogen is removed through scission while pi bonds are formed by cross-linking between main chains. These changes cause the energy band of PE to show dramatic variation from a wide to a narrow (down to approximately 0.8 eV) band-gap. At the highest dose (10(10) C m(-2)) used herein, an illuminated area of PE becomes quite similar in properties to graphitic amorphous carbon. On the other hand, the size of the beam-affected area is as small as roughly 50 nm in diameter. Since the extent of the modifications can be tailored in a controllable way by the dose, these findings may be fundamental for the utilization of a conventional polymer in nanotechnology.
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Affiliation(s)
- Hansoo Kim
- Microscopy and Imaging Center, Texas A&M, College Station, Texas 77843, USA.
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Sezen M, Plank H, Nellen PM, Meier S, Chernev B, Grogger W, Fisslthaler E, List EJW, Scherf U, Poelt P. Ion beam degradation analysis of poly(3-hexylthiophene) (P3HT): can cryo-FIB minimize irradiation damage? Phys Chem Chem Phys 2009; 11:5130-3. [DOI: 10.1039/b816893h] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Jeon HS, Dixit PS, Yim H. Dewetting of thin polystyrene films absorbed on epoxy coated substrates. J Chem Phys 2005; 122:104707. [PMID: 15836345 DOI: 10.1063/1.1858853] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Various characteristics of dewetting of thin polystyrene (PS) films absorbed on highly cross-linked epoxy-coated and silicon oxide covered substrates are studied as a function of PS film thickness (20<h<1300 A) by optical microscopy, atomic force microscopy, and x-ray and neutron reflectivity. For a silicon oxide covered substrate, the nucleation of holes and growth (NG) mechanism is observed for h>h(c1) whereas the spinodal dewetting (SD) occurs through the growth of surface undulations for h<h(c1), where h(c1) is approximately 4R(g). For an epoxy-coated substrate, the NG mechanism is observed for h>h(c2) while the SD mechanism is observed for h<h(c2), where h(c2) is approximately 6R(g). We demonstrate that the highly cross-linked epoxy-coated silicon substrate leads to retardation of the PS film dewetting in comparison to the silicon oxide covered silicon substrate. Moreover, we confirm that the epoxy-coated substrate leads to a significant decrease in the fraction of dewetted area at the apparent equilibrium stage of dewetting due to the anchoring effect of PS molecules caused from the cross-linked networks of the epoxy layer. In contrast the retardation effect of the epoxy-coated substrate on the rate of dewetting is more remarkable for relatively thinner PS films (h< approximately 800 A) than thicker films ( approximately 800<h<1300 A) since the short-range intermolecular interactions are dominant for relatively thin PS films. Thus the highly cross-linked epoxy-coated substrate has a large influence on the kinetics, morphology, and mechanism of dewetting of thin PS films.
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Affiliation(s)
- H S Jeon
- Department of Petroleum and Chemical Engineering, New Mexico Institute of Mining and Technology, Socorro, NM 87801, USA
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