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Sunday DF, Thelen JL, Zhou C, Ren J, Nealey PF, Kline RJ. Buried Structure in Block Copolymer Films Revealed by Soft X-ray Reflectivity. ACS NANO 2021; 15:9577-9587. [PMID: 34014640 DOI: 10.1021/acsnano.0c09907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Interactions between polymers and surfaces can be used to influence properties including mechanical performance in nanocomposites, the glass transition temperature, and the orientation of thin film block copolymers (BCPs). In this work we investigate how specific interactions between the substrate and BCPs with varying substrate affinity impact the interfacial width between polymer components. The interface width is generally assumed to be a function of the BCP properties and independent of the surface affinity or substrate proximity. Using resonant soft X-ray reflectivity the optical constants of the film can be controlled by changing the incident energy, thereby varying the depth sensitivity of the measurement. Resonant soft X-ray reflectivity measurements were conducted on films of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) and PS-b-poly(methyl methacrylate) (PS-b-PMMA), where the thickness of the film was varied from half the periodicity (L0) of the BCP to 5.5 L0. The results of this measurement on the PS-b-P2VP films show a significant expansion of the interface width immediately adjacent to the surface. This is likely caused by the strong adsorption of P2VP to the substrate, which constrains the mobility of the junction points, preventing them from reaching their equilibrium distribution and expanding the observed interface width. The interface width decays toward equilibrium moving away from the substrate, with the decay rate being a function of film thickness below a critical limit. The PMMA block appears to be more mobile, and the BCP interfaces near the substrate match their equilibrium value.
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Affiliation(s)
- Daniel F Sunday
- Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Jacob L Thelen
- Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
| | - Chun Zhou
- Institute for Molecular Engineering, University of Chicago, 5801 S Ellis Ave, Chicago, Illinois 60637, United States
| | - Jiaxing Ren
- Institute for Molecular Engineering, University of Chicago, 5801 S Ellis Ave, Chicago, Illinois 60637, United States
| | - Paul F Nealey
- Institute for Molecular Engineering, University of Chicago, 5801 S Ellis Ave, Chicago, Illinois 60637, United States
| | - R Joseph Kline
- Materials Science and Engineering Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States
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Rabani R, Sadafi H, Machrafi H, Abbasi M, Haut B, Dauby P. Influence of evaporation on the morphology of a thin film of a partially miscible binary mixture. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2020.126001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Spampinato N, Pecastaings G, Maglione M, Hadziioannou G, Pavlopoulou E. Non-destructive depth-dependent morphological characterization of ferroelectric:semiconducting polymer blend films. Colloid Polym Sci 2021. [DOI: 10.1007/s00396-020-04803-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Roy D, Sinha S, Wang CH, Yang YW, Mukherjee M. Interfacial Interaction of Absorbate Copper Phthalocyanine with PVDF Based Ferroelectric Polymer Substrates: A Spectroscopic Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4607-4618. [PMID: 32282215 DOI: 10.1021/acs.langmuir.0c00218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Studies of CuPc thin films on underlying ferroelectric copolymeric and terpolymeric substrates have been performed by ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Work function (WF) and highest occupied molecular orbital (HOMO) energy level shift observed from UPS spectroscopy for successive deposition of CuPc molecules on ferroelectric polymer surfaces confirm the formation of interface dipole at the CuPc-ferroelectric polymer interface owing to charge transfer from the tailing region of the CuPc HOMO density of states (DOS) to the ferroelectric polymer layer. According to our thickness dependent XPS data, CuPc molecules are coupled to the organic ferroelectric surfaces through the central metal atom of the CuPc molecules, i.e., copper atom, and the halogens of underlying ferroelectric polymer surfaces, and hence support the charge transfer phenomenon from CuPc molecules to the ferroelectric polymer substrate. Polarization dependent NEXAFS results reveal that CuPc molecules retain their tilted geometrical configuration even at submonolayer thickness of the molecular films on both ferroelectric surfaces and confirms the electronic structural disturbance associated with structural modification of CuPc molecules due to interfacial charge transfer. Therefore, the energy level alignment with increment in the thickness of CuPc films at both the organic semiconductor-ferroelectric polymer interface is controlled by the charge transfer phenomenon from deposited CuPc molecules to the organic ferroelectric substrates. Our results provide a clear understanding about chemical interactions, molecular configurations, energy level alignment, and their correlation at CuPc/polymeric ferroelectric interfaces that can be important for organic nonvolatile memory and synaptic based thin-film transistor devices.
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Affiliation(s)
- Dhrubojyoti Roy
- Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati-781039, India
- Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata-700064, India
| | - Sumona Sinha
- S. N. Bose National Central for Basic Sciences, Kolkata-700106, India
| | - Chia-Hsin Wang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
| | - Yaw-Wen Yang
- National Synchrotron Radiation Research Center, Hsinchu, 30076, Taiwan
- Department of Chemistry, National Tsing-Hua University, Hsinchu, 30013, Taiwan
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Ghittorelli M, Lenz T, Sharifi Dehsari H, Zhao D, Asadi K, Blom PWM, Kovács-Vajna ZM, de Leeuw DM, Torricelli F. Quantum tunnelling and charge accumulation in organic ferroelectric memory diodes. Nat Commun 2017; 8:15741. [PMID: 28604664 PMCID: PMC5477493 DOI: 10.1038/ncomms15841] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 05/08/2017] [Indexed: 11/21/2022] Open
Abstract
Non-volatile memories-providing the information storage functionality-are crucial circuit components. Solution-processed organic ferroelectric memory diodes are the non-volatile memory candidate for flexible electronics, as witnessed by the industrial demonstration of a 1 kbit reconfigurable memory fabricated on a plastic foil. Further progress, however, is limited owing to the lack of understanding of the device physics, which is required for the technological implementation of high-density arrays. Here we show that ferroelectric diodes operate as vertical field-effect transistors at the pinch-off. The tunnelling injection and charge accumulation are the fundamental mechanisms governing the device operation. Surprisingly, thermionic emission can be disregarded and the on-state current is not space charge limited. The proposed model explains and unifies a wide range of experiments, provides important design rules for the implementation of organic ferroelectric memory diodes and predicts an ultimate theoretical array density of up to 1012 bit cm-2.
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Affiliation(s)
- Matteo Ghittorelli
- Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Thomas Lenz
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | | | - Dong Zhao
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Kamal Asadi
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Paul W. M. Blom
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Zsolt M. Kovács-Vajna
- Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
| | - Dago M. de Leeuw
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629 HS Delft, The Netherlands
| | - Fabrizio Torricelli
- Department of Information Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy
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Dissipative particle dynamics simulation of phase separation in semiconducting/ferroelectric blend resistive films. POLYMER 2017. [DOI: 10.1016/j.polymer.2017.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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