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Downing JR, Diaz-Arauzo S, Chaney LE, Tsai D, Hui J, Seo JWT, Cohen DR, Dango M, Zhang J, Williams NX, Qian JH, Dunn JB, Hersam MC. Centrifuge-Free Separation of Solution-Exfoliated 2D Nanosheets via Cross-Flow Filtration. Adv Mater 2023; 35:e2212042. [PMID: 36934307 DOI: 10.1002/adma.202212042] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 02/26/2023] [Indexed: 06/16/2023]
Abstract
Solution-processed graphene is a promising material for numerous high-volume applications including structural composites, batteries, sensors, and printed electronics. However, the polydisperse nature of graphene dispersions following liquid-phase exfoliation poses major manufacturing challenges, as incompletely exfoliated graphite flakes must be removed to achieve optimal properties and downstream performance. Incumbent separation schemes rely on centrifugation, which is highly energy-intensive and limits scalable manufacturing. Here, cross-flow filtration (CFF) is introduced as a centrifuge-free processing method that improves the throughput of graphene separation by two orders of magnitude. By tuning membrane pore sizes between microfiltration and ultrafiltration length scales, CFF can also be used for efficient recovery of solvents and stabilizing polymers. In this manner, life cycle assessment and techno-economic analysis reveal that CFF reduces greenhouse gas emissions, fossil energy usage, water consumption, and specific production costs of graphene manufacturing by 57%, 56%, 63%, and 72%, respectively. To confirm that CFF produces electronic-grade graphene, CFF-processed graphene nanosheets are formulated into printable inks, leading to state-of-the-art thin-film conductivities exceeding 104 S m-1 . This CFF methodology can likely be generalized to other van der Waals layered solids, thus enabling sustainable manufacturing of the diverse set of applications currently being pursued for 2D materials.
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Affiliation(s)
- Julia R Downing
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | - Santiago Diaz-Arauzo
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | - Lindsay E Chaney
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | - Daphne Tsai
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | - Janan Hui
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| | - Jung-Woo T Seo
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | | | - Michael Dango
- Cytiva, 100 Results Way, Marlborough, MA, 01752, USA
| | - Jinrui Zhang
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| | - Nicholas X Williams
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | - Justin H Qian
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
| | - Jennifer B Dunn
- Department of Chemical and Biological Engineering, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, 2220 Campus Dr., Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, IL, 60208, USA
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2
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Park KY, Zhu Y, Torres-Castanedo CG, Jung HJ, Luu NS, Kahvecioglu O, Yoo Y, Seo JWT, Downing JR, Lim HD, Bedzyk MJ, Wolverton C, Hersam MC. Elucidating and Mitigating High-Voltage Degradation Cascades in Cobalt-Free LiNiO 2 Lithium-Ion Battery Cathodes. Adv Mater 2022; 34:e2106402. [PMID: 34731506 DOI: 10.1002/adma.202106402] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/16/2021] [Indexed: 06/13/2023]
Abstract
LiNiO2 (LNO) is a promising cathode material for next-generation Li-ion batteries due to its exceptionally high capacity and cobalt-free composition that enables more sustainable and ethical large-scale manufacturing. However, its poor cycle life at high operating voltages over 4.1 V impedes its practical use, thus motivating efforts to elucidate and mitigate LiNiO2 degradation mechanisms at high states of charge. Here, a multiscale exploration of high-voltage degradation cascades associated with oxygen stacking chemistry in cobalt-free LiNiO2 , is presented. Lattice oxygen loss is found to play a critical role in the local O3-O1 stacking transition at high states of charge, which subsequently leads to Ni-ion migration and irreversible stacking faults during cycling. This undesirable atomic-scale structural evolution accelerates microscale electrochemical creep, cracking, and even bending of layers, ultimately resulting in macroscopic mechanical degradation of LNO particles. By employing a graphene-based hermetic surface coating, oxygen loss is attenuated in LNO at high states of charge, which suppresses the initiation of the degradation cascade and thus substantially improves the high-voltage capacity retention of LNO. Overall, this study provides mechanistic insight into the high-voltage degradation of LNO, which will inform ongoing efforts to employ cobalt-free cathodes in Li-ion battery technology.
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Affiliation(s)
- Kyu-Young Park
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Graduate Institute of Ferrous and Energy Materials Technology, Pohang University of Science and Technology, Pohang, Kyungbuk, 37673, Republic of Korea
| | - Yizhou Zhu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | | | - Hee Joon Jung
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- NUANCE Center, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA
| | - Norman S Luu
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Ozge Kahvecioglu
- Argonne National Laboratory, Applied Materials Division, 9700 South Cass Avenue, Lemont, IL, 60439, USA
| | - Yiseul Yoo
- Center for Energy Storage Research, Korea Institute of Science and Technology (KIST), Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul, 02792, Republic of Korea
- Department of Materials Science and Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jung-Woo T Seo
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Volexion, Inc., 4809 North Ravenswood Avenue, Chicago, IL, 60640, USA
| | - Julia R Downing
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Hee-Dae Lim
- Center for Energy Storage Research, Korea Institute of Science and Technology (KIST), Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul, 02792, Republic of Korea
| | - Michael J Bedzyk
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Physics and Astronomy, Northwestern University, Evanston, IL, 60208, USA
| | - Christopher Wolverton
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
- Department of Electrical and Computer Engineering, Northwestern University, Evanston, IL, 60208, USA
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3
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Chen KS, Xu R, Luu NS, Secor EB, Hamamoto K, Li Q, Kim S, Sangwan VK, Balla I, Guiney LM, Seo JWT, Yu X, Liu W, Wu J, Wolverton C, Dravid VP, Barnett SA, Lu J, Amine K, Hersam MC. Comprehensive Enhancement of Nanostructured Lithium-Ion Battery Cathode Materials via Conformal Graphene Dispersion. Nano Lett 2017; 17:2539-2546. [PMID: 28240911 DOI: 10.1021/acs.nanolett.7b00274] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Efficient energy storage systems based on lithium-ion batteries represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Nanostructured electrode materials present compelling opportunities for high-performance lithium-ion batteries, but inherent problems related to the high surface area to volume ratios at the nanometer-scale have impeded their adoption for commercial applications. Here, we demonstrate a materials and processing platform that realizes high-performance nanostructured lithium manganese oxide (nano-LMO) spinel cathodes with conformal graphene coatings as a conductive additive. The resulting nanostructured composite cathodes concurrently resolve multiple problems that have plagued nanoparticle-based lithium-ion battery electrodes including low packing density, high additive content, and poor cycling stability. Moreover, this strategy enhances the intrinsic advantages of nano-LMO, resulting in extraordinary rate capability and low temperature performance. With 75% capacity retention at a 20C cycling rate at room temperature and nearly full capacity retention at -20 °C, this work advances lithium-ion battery technology into unprecedented regimes of operation.
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Affiliation(s)
- Kan-Sheng Chen
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Rui Xu
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Norman S Luu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Ethan B Secor
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Koichi Hamamoto
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Qianqian Li
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Soo Kim
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinod K Sangwan
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Itamar Balla
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Linda M Guiney
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Jung-Woo T Seo
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Xiankai Yu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Weiwei Liu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Jinsong Wu
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Chris Wolverton
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Vinayak P Dravid
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Scott A Barnett
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
| | - Jun Lu
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Khalil Amine
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States
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4
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Zhu J, Kang J, Kang J, Jariwala D, Wood JD, Seo JWT, Chen KS, Marks TJ, Hersam MC. Solution-Processed Dielectrics Based on Thickness-Sorted Two-Dimensional Hexagonal Boron Nitride Nanosheets. Nano Lett 2015; 15:7029-7036. [PMID: 26348822 DOI: 10.1021/acs.nanolett.5b03075] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Gate dielectrics directly affect the mobility, hysteresis, power consumption, and other critical device metrics in high-performance nanoelectronics. With atomically flat and dangling bond-free surfaces, hexagonal boron nitride (h-BN) has emerged as an ideal dielectric for graphene and related two-dimensional semiconductors. While high-quality, atomically thin h-BN has been realized via micromechanical cleavage and chemical vapor deposition, existing liquid exfoliation methods lack sufficient control over h-BN thickness and large-area film quality, thus limiting its use in solution-processed electronics. Here, we employ isopycnic density gradient ultracentrifugation for the preparation of monodisperse, thickness-sorted h-BN inks, which are subsequently layer-by-layer assembled into ultrathin dielectrics with low leakage currents of 3 × 10(-9) A/cm(2) at 2 MV/cm and high capacitances of 245 nF/cm(2). The resulting solution-processed h-BN dielectric films enable the fabrication of graphene field-effect transistors with negligible hysteresis and high mobilities up to 7100 cm(2) V(-1) s(-1) at room temperature. These h-BN inks can also be used as coatings on conventional dielectrics to minimize the effects of underlying traps, resulting in improvements in overall device performance. Overall, this approach for producing and assembling h-BN dielectric inks holds significant promise for translating the superlative performance of two-dimensional heterostructure devices to large-area, solution-processed nanoelectronics.
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Affiliation(s)
- Jian Zhu
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Joohoon Kang
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Junmo Kang
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Deep Jariwala
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Joshua D Wood
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Jung-Woo T Seo
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Kan-Sheng Chen
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Tobin J Marks
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
| | - Mark C Hersam
- Department of Materials Science and Engineering, ‡Graduate Program in Applied Physics, §Department of Chemistry, and ∥Department of Medicine, Northwestern University , Evanston, Illinois 60208, United States
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5
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Abstract
We report on the dynamics of spatial temperature distributions in aligned semiconducting carbon nanotube array devices with submicrometer channel lengths. By using high-resolution optical microscopy in combination with electrical transport measurements, we observe under steady state bias conditions the emergence of time-variable, local temperature maxima with dimensions below 300 nm, and temperatures above 400 K. On the basis of time domain cross-correlation analysis, we investigate how the intensity fluctuations of the thermal radiation patterns are correlated with the overall device current. The analysis reveals the interdependence of electrical current fluctuations and time-variable hot spot formation that limits the overall device performance and, ultimately, may cause device degradation. The findings have implications for the future development of carbon nanotube-based technologies.
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Affiliation(s)
- Michael Engel
- IBM Thomas J. Watson Research Center , Yorktown Heights, New York 10598, United States
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6
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Geier ML, Prabhumirashi PL, McMorrow JJ, Xu W, Seo JWT, Everaerts K, Kim CH, Marks TJ, Hersam MC. Subnanowatt carbon nanotube complementary logic enabled by threshold voltage control. Nano Lett 2013; 13:4810-4814. [PMID: 24020970 DOI: 10.1021/nl402478p] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In this Letter, we demonstrate thin-film single-walled carbon nanotube (SWCNT) complementary metal-oxide-semiconductor (CMOS) logic devices with subnanowatt static power consumption and full rail-to-rail voltage transfer characteristics as is required for logic gate cascading. These results are enabled by a local metal gate structure that achieves enhancement-mode p-type and n-type SWCNT thin-film transistors (TFTs) with widely separated and symmetric threshold voltages. These complementary SWCNT TFTs are integrated to demonstrate CMOS inverter, NAND, and NOR logic gates at supply voltages as low as 0.8 V with ideal rail-to-rail operation, subnanowatt static power consumption, high gain, and excellent noise immunity. This work provides a direct pathway for solution processable, large area, power efficient SWCNT advanced logic circuits and systems.
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Affiliation(s)
- Michael L Geier
- Department of Materials Science and Engineering and ‡Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
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7
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Ha M, Seo JWT, Prabhumirashi PL, Zhang W, Geier ML, Renn MJ, Kim CH, Hersam MC, Frisbie CD. Aerosol jet printed, low voltage, electrolyte gated carbon nanotube ring oscillators with sub-5 μs stage delays. Nano Lett 2013; 13:954-960. [PMID: 23394463 DOI: 10.1021/nl3038773] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A central challenge for printed electronics is to achieve high operating frequencies (short transistor switching times) at low supply biases compatible with thin film batteries. In this report, we demonstrate partially printed five-stage ring oscillators with >20 kHz operating frequencies and stage delays <5 μs at supply voltages below 3 V. The fastest ring oscillator achieved 1.2 μs delay time at 2 V supply. The inverter stages in these ring oscillators were based on ambipolar thin film transistors (TFTs) employing semiconducting, single-walled carbon nanotube (CNT) networks and a high capacitance (∼1 μF/cm(2)) ion gel electrolyte as the gate dielectric. All materials except the source and drain electrodes were aerosol jet printed. The TFTs exhibited high electron and hole mobilities (∼20 cm(2)/(V s)) and ON/OFF current ratios (up to 10(5)). Inverter switching times t were systematically characterized as a function of transistor channel length and ionic conductivity of the gel dielectric, demonstrating that both the semiconductor and the ion gel play a role in switching speed. Quantitative scaling analysis suggests that with suitable optimization low voltage, printed ion gel gated CNT inverters could operate at frequencies on the order of 1 MHz.
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Affiliation(s)
- Mingjing Ha
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, Minnesota 55455, United States
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Shastry TA, Seo JWT, Lopez JJ, Arnold HN, Kelter JZ, Sangwan VK, Lauhon LJ, Marks TJ, Hersam MC. Large-area, electronically monodisperse, aligned single-walled carbon nanotube thin films fabricated by evaporation-driven self-assembly. Small 2013; 9:45-51. [PMID: 22987547 DOI: 10.1002/smll.201201398] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Indexed: 06/01/2023]
Abstract
By varying the evaporation conditions and the nanotube and surfactant concentrations, large-area, aligned single-walled carbon nanotube (SWCNT) thin films are fabricated from electronically monodisperse SWCNT solutions by evaporation-driven self-assembly with precise control over the thin film growth geometry. Tunability is possible from 0.5 μm stripes to continuous thin films. The resulting SWCNT thin films possess highly anisotropic electrical and optical properties that are well suited for transparent conductor applications.
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Affiliation(s)
- Tejas A Shastry
- Department of Materials Science, Northwestern University, 2220 Campus Dr., Evanston, IL 60208-3108, USA
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9
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Sire C, Ardiaca F, Lepilliet S, Seo JWT, Hersam MC, Dambrine G, Happy H, Derycke V. Flexible gigahertz transistors derived from solution-based single-layer graphene. Nano Lett 2012; 12:1184-1188. [PMID: 22283460 DOI: 10.1021/nl203316r] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Flexible electronics mostly relies on organic semiconductors but the limited carrier velocity in polymers and molecular films prevents their use at frequencies above a few megahertz. Conversely, the high potential of graphene for high-frequency electronics on rigid substrates was recently demonstrated. We conducted the first study of solution-based graphene transistors at gigahertz frequencies, and we show that solution-based single-layer graphene ideally combines the required properties to achieve high speed flexible electronics on plastic substrates. Our graphene flexible transistors have current gain cutoff frequencies of 2.2 GHz and power gain cutoff frequencies of 550 MHz. Radio frequency measurements directly performed on bent samples show remarkable mechanical stability of these devices and demonstrate the advantages of solution-based graphene field-effect transistors over other types of flexible transistors based on organic materials.
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Affiliation(s)
- Cédric Sire
- CEA Saclay, IRAMIS, Service de Physique de l'Etat Condensé (URA 2464), Laboratoire d'Electronique Moléculaire, F-91191 Gif sur Yvette, France
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10
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Antaris AL, Seo JWT, Green AA, Hersam MC. Sorting single-walled carbon nanotubes by electronic type using nonionic, biocompatible block copolymers. ACS Nano 2010; 4:4725-32. [PMID: 20669897 DOI: 10.1021/nn101363m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
As-synthesized single-walled carbon nanotubes (SWNTs) typically possess a range of diameters and electronic properties. This polydispersity has hindered the development of many SWNT-based technologies and encouraged the development of postsynthetic methods for sorting SWNTs by their physical and electronic structure. Herein, we demonstrate that nonionic, biocompatible block copolymers can be used to isolate semiconducting and metallic SWNTs using density gradient ultracentrifugation. Separations conducted with different Pluronic block copolymers reveal that Pluronics with shorter hydrophobic chain lengths lead to higher purity semiconducting SWNTs, resulting in semiconducting purity levels in excess of 99% obtained for Pluronic F68. In contrast, X-shaped Tetronic block copolymers display an affinity for metallic SWNTs, yielding metallic purity levels of 74% for Tetronic 1107. These results suggest that high fidelity and high yield density gradient separations can be achieved using nonionic block copolymers with rationally designed homopolymer segments, thus generating biocompatible monodisperse SWNTs for a range of applications.
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Affiliation(s)
- Alexander L Antaris
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208-3108, USA
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