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Buzio R, Gerbi A, Bernini C, Repetto L, Silva A, Vanossi A. Dissipation Mechanisms and Superlubricity in Solid Lubrication by Wet-Transferred Solution-Processed Graphene Flakes: Implications for Micro Electromechanical Devices. ACS APPLIED NANO MATERIALS 2023; 6:11443-11454. [PMID: 37469503 PMCID: PMC10352959 DOI: 10.1021/acsanm.3c01477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 05/30/2023] [Indexed: 07/21/2023]
Abstract
Solution-processed few-layer graphene flakes, dispensed to rotating and sliding contacts via liquid dispersions, are gaining increasing attention as friction modifiers to achieve low friction and wear at technologically relevant interfaces. Vanishing friction states, i.e., superlubricity, have been documented for nearly-ideal nanoscale contacts lubricated by individual graphene flakes. However, there is no clear understanding if superlubricity might persist for larger and morphologically disordered contacts, as those typically obtained by incorporating wet-transferred solution-processed flakes into realistic microscale contact junctions. In this study, we address the friction performance of solution-processed graphene flakes by means of colloidal probe atomic force microscopy. We use a state-of-the-art additive-free aqueous dispersion to coat micrometric silica beads, which are then sled under ambient conditions against prototypical material substrates, namely, graphite and the transition metal dichalcogenides (TMDs) MoS2 and WS2. High resolution microscopy proves that the random assembly of the wet-transferred flakes over the silica probes results into an inhomogeneous coating, formed by graphene patches that control contact mechanics through tens-of-nanometers tall protrusions. Atomic-scale friction force spectroscopy reveals that dissipation proceeds via stick-slip instabilities. Load-controlled transitions from dissipative stick-slip to superlubric continuous sliding may occur for the graphene-graphite homojunctions, whereas single- and multiple-slips dissipative dynamics characterizes the graphene-TMD heterojunctions. Systematic numerical simulations demonstrate that the thermally activated single-asperity Prandtl-Tomlinson model comprehensively describes friction experiments involving different graphene-coated colloidal probes, material substrates, and sliding regimes. Our work establishes experimental procedures and key concepts that enable mesoscale superlubricity by wet-transferred liquid-processed graphene flakes. Together with the rise of scalable material printing techniques, our findings support the use of such nanomaterials to approach superlubricity in micro electromechanical systems.
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Affiliation(s)
- Renato Buzio
- CNR-SPIN, C.so F.M. Perrone 24, Genova 16152, Italy
| | - Andrea Gerbi
- CNR-SPIN, C.so F.M. Perrone 24, Genova 16152, Italy
| | | | - Luca Repetto
- Dipartimento
di Fisica, Università degli Studi
di Genova, Via Dodecaneso 33, Genova 16146, Italy
| | - Andrea Silva
- CNR-IOM
Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali, c/o SISSA, Via Bonomea 265, Trieste 34136, Italy
- International
School for Advanced Studies (SISSA), Via Bonomea 265, Trieste 34136, Italy
| | - Andrea Vanossi
- CNR-IOM
Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali, c/o SISSA, Via Bonomea 265, Trieste 34136, Italy
- International
School for Advanced Studies (SISSA), Via Bonomea 265, Trieste 34136, Italy
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Buzio R, Gerbi A, Bernini C, Repetto L, Vanossi A. Sliding Friction and Superlubricity of Colloidal AFM Probes Coated by Tribo-Induced Graphitic Transfer Layers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:12570-12580. [PMID: 36190908 DOI: 10.1021/acs.langmuir.2c02030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Colloidal probe atomic force microscopy (AFM) allows us to explore sliding friction phenomena in graphite contacts of nominal lateral size up to hundreds of nanometers. It is known that contact formation involves tribo-induced material transfer of graphite flakes from the graphitic substrate to the colloidal probe. In this context, sliding states with nearly vanishing friction, i.e., superlubricity, may set in. A comprehensive investigation of the transfer layer properties is mandatory to ascertain the origin of superlubricity. Here we explore the friction response of micrometric beads, of different size and pristine surface roughness, sliding on graphite under ambient conditions. We show that such tribosystems undergo a robust transition toward a low-adhesion, low-friction state dominated by mechanical interactions at one dominant tribo-induced nanocontact. Friction force spectroscopy reveals that the nanocontact can be superlubric or dissipative, in fact undergoing a load-driven transition from dissipative stick-slip to continuous superlubric sliding. This behavior is excellently described by the thermally activated, single-asperity Prandtl-Tomlinson model. Our results indicate that upon formation of the transfer layer, friction depends on the energy landscape experienced by the topographically highest tribo-induced nanoasperity. We consistently find larger dissipation when the tribo-induced nanoasperity is slid against surfaces with higher atomic corrugation than graphite, like MoS2 and WS2, in prototypical van der Waals layered heterojunctions.
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Affiliation(s)
- Renato Buzio
- CNR-SPIN, C.so F.M. Perrone 24, Genova16152, Italy
| | - Andrea Gerbi
- CNR-SPIN, C.so F.M. Perrone 24, Genova16152, Italy
| | | | - Luca Repetto
- Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, Genova16146, Italy
| | - Andrea Vanossi
- CNR-IOM Consiglio Nazionale delle Ricerche - Istituto Officina dei Materiali, c/o SISSA, Via Bonomea 265, Trieste34136, Italy
- International School for Advanced Studies (SISSA), Via Bonomea 265, Trieste34136, Italy
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Li D, Titov E, Roedel M, Kolb V, Goetz S, Mitric R, Pflaum J, Brixner T. Correlating Nanoscale Optical Coherence Length and Microscale Topography in Organic Materials by Coherent Two-Dimensional Microspectroscopy. NANO LETTERS 2020; 20:6452-6458. [PMID: 32786935 DOI: 10.1021/acs.nanolett.0c02146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Many nanotechnology materials rely on a hierarchical structure ranging from the nanometer scale to the micrometer scale. Their interplay determines the nanoscale optical coherence length, which plays a key role in energy transport and radiative decay and, thus, the optoelectronic applications. However, it is challenging to detect optical coherence length in multiscale structures with existing methods. Techniques such as atomic force microscopy and transmission electron microscopy are not sensitive to optical coherence length. Linear absorption and fluorescence spectroscopy methods, on the other hand, were generally limited by inhomogeneous broadening, which often obstructs the determination of nanoscale coherence length. Here, we carry out coherent two-dimensional microspectroscopy to obtain a map of the local optical coherence length within a hierarchically structured molecular film. Interestingly, the nanoscale coherence length is found to correlate with microscale topography, suggesting a perspective for controlling structural coherence on molecular length scales by appropriate microscopic growth conditions.
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Affiliation(s)
- Donghai Li
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Evgenii Titov
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Maximilian Roedel
- Lehrstuhl für Experimentelle Physik VI, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Verena Kolb
- Lehrstuhl für Experimentelle Physik VI, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Sebastian Goetz
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Roland Mitric
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jens Pflaum
- Lehrstuhl für Experimentelle Physik VI, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Bavarian Center for Applied Energy Research e.V. (ZAE Bayern), Magdalene-Schoch-Str. 3, 97074 Würzburg, Germany
| | - Tobias Brixner
- Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany
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Perylene-Diimide Molecules with Cyano Functionalization for Electron-Transporting Transistors. ELECTRONICS 2019. [DOI: 10.3390/electronics8020249] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Core-cyanated perylene diimide (PDI_CY) derivatives are molecular compounds exhibiting an uncommon combination of appealing properties, including remarkable oxidative stability, high electron affinities, and excellent self-assembling properties. Such features made these compounds the subject of study for several research groups aimed at developing electron-transporting (n-type) devices with superior charge transport performances. After about fifteen years since the first report, field-effect transistors based on PDI_CY thin films are still intensely investigated by the scientific community for the attainment of n-type devices that are able to balance the performances of the best p-type ones. In this review, we summarize the main results achieved by our group in the fabrication and characterization of transistors based on PDI8-CN2 and PDIF-CN2 molecules, undoubtedly the most renowned compounds of the PDI_CY family. Our attention was mainly focused on the electrical properties, both at the micro and nanoscale, of PDI8-CN2 and PDIF-CN2 films deposited using different evaporation techniques. Specific topics, such as the contact resistance phenomenon, the bias stress effect, and the operation in liquid environment, have been also analyzed.
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Xu H, Jin J, Zhang J, Sheng P, Li Y, Yi M, Huang W. Investigation of Self-Assembly and Charge-Transport Property of One-dimensional PDI₈-CN₂ Nanowires by Solvent-Vapor Annealing. MATERIALS (BASEL, SWITZERLAND) 2019; 12:E438. [PMID: 30709000 PMCID: PMC6384653 DOI: 10.3390/ma12030438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 01/23/2019] [Accepted: 01/26/2019] [Indexed: 12/02/2022]
Abstract
One-dimensional (1D) nanowires have attracted great interest, while air-stable n-type 1D nanowires still remain scarce. Herein, we present solvent-vapor annealing (SVA) made nanowires based on perylene tetracarboxylic diimide (PDI) derivative. It was found that the spin-coated thin films reorganized into nanowires distributed all over the substrate, as a result of the following solvent-vapor annealing effect. Cooperating with the atomic force microscopy and fluorescence microscopy characterization, the PDI₈-CN₂ molecules were supposed to conduct a long-range and entire transport to form the 1D nanowires through the SVA process, which may guarantee its potential morphology tailoring ability. In addition, the nanowire-based transistors displayed air stable electron mobility reaching to 0.15 cm² V-1 s-1, attributing to effective in situ reassembly. Owing to the broader application of organic small-molecule nanowires, this work opens up an attractive approach for exploring new high-performance micro- and nanoelectronics.
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Affiliation(s)
- Haixiao Xu
- Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
| | - Jianqun Jin
- Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
| | - Jing Zhang
- Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
| | - Peng Sheng
- Material Laboratory of State Grid Corporation of China, State Key laboratory of Advanced Transmission Technology, Global Energy Interconnection Research Institute, Beijing 102211, China.
| | - Yu Li
- Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
| | - Mingdong Yi
- Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
| | - Wei Huang
- Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210023, China.
- Shaanxi Institute of Flexible Electronics (SIFE), Northwestern Polytechnical University (NPU), 127 West Youyi Road, Xi'an 710072, Shaanxi, China.
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Post-Deposition Wetting and Instabilities in Organic Thin Films by Supersonic Molecular Beam Deposition. Sci Rep 2018; 8:12015. [PMID: 30104704 PMCID: PMC6089966 DOI: 10.1038/s41598-018-30567-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 07/31/2018] [Indexed: 11/08/2022] Open
Abstract
We discuss the formation and post-deposition instability of nanodrop-like structures in thin films of PDIF-CN2 (a perylene derivative) deposited via supersonic molecular beam deposition technique on highly hydrophobic substrates at room temperature. The role of the deposition rate on the characteristic lengths of the organic nanodrops has been investigated by a systematic analysis of atomic force microscope images of the thin films and through the use of the height-height correlation function. The nanodrops appear to be a metastable configuration for the freshly-deposited films. For this reason, post-deposition wetting effect has been examined with unprecedented accuracy throughout a year of experimental observations. The observed time scales, from few hours to months, are related to the growth rate, and characterize the thin films morphological reordering from three-dimensional nanodrops to a well-connected terraced film. While the interplay between adhesion and cohesion energies favors the formation of 3D-mounted structures during the growth, wetting phenomenon following the switching off of the molecular flux is found to be driven by an instability. A slow rate downhill process survives at the molecular flux shutdown and it is accompanied and maybe favored by the formation of a precursor layer composed of more lying molecules. These results are supported by simulations based on a non-linear stochastic model. The instability has been simulated, for both the growth and the post-growth evolution. To better reproduce the experimental data it is needed to introduce a surface equalizer term characterized by a relaxation time taking into account the presence of a local mechanism of molecular correlation.
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