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Guiney LM, Mansukhani ND, Jakus AE, Wallace SG, Shah RN, Hersam MC. Three-Dimensional Printing of Cytocompatible, Thermally Conductive Hexagonal Boron Nitride Nanocomposites. NANO LETTERS 2018; 18:3488-3493. [PMID: 29709193 DOI: 10.1021/acs.nanolett.8b00555] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hexagonal boron nitride (hBN) is a thermally conductive yet electrically insulating two-dimensional layered nanomaterial that has attracted significant attention as a dielectric for high-performance electronics in addition to playing a central role in thermal management applications. Here, we report a high-content hBN-polymer nanocomposite ink, which can be 3D printed to form mechanically robust, self-supporting constructs. In particular, hBN is dispersed in poly(lactic- co-glycolic acid) and 3D printed at room temperature through an extrusion process to form complex architectures. These constructs can be 3D printed with a composition of up to 60% vol hBN (solids content) while maintaining high mechanical flexibility and stretchability. The presence of hBN within the matrix results in enhanced thermal conductivity (up to 2.1 W K-1 m-1) directly after 3D printing with minimal postprocessing steps, suggesting utility in thermal management applications. Furthermore, the constructs show high levels of cytocompatibility, making them suitable for use in the field of printed bioelectronics.
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Wang X, Lee JH, Li R, Liao YP, Kang J, Chang CH, Guiney LM, Mirshafiee V, Li L, Lu J, Xia T, Hersam MC, Nel AE. Toxicological Profiling of Highly Purified Single-Walled Carbon Nanotubes with Different Lengths in the Rodent Lung and Escherichia Coli. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1703915. [PMID: 29733549 PMCID: PMC6239219 DOI: 10.1002/smll.201703915] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/14/2018] [Indexed: 05/13/2023]
Abstract
Carbon nanotubes (CNTs) exhibit a number of physicochemical properties that contribute to adverse biological outcomes. However, it is difficult to define the independent contribution of individual properties without purified materials. A library of highly purified single-walled carbon nanotubes (SWCNTs) of different lengths is prepared from the same base material by density gradient ultracentrifugation, designated as short (318 nm), medium (789 nm), and long (1215 nm) SWCNTs. In vitro screening shows length-dependent interleukin-1β (IL-1β) production, in order of long > medium > short. However, there are no differences in transforming growth factor-β1 production in BEAS-2B cells. Oropharyngeal aspiration shows that all the SWCNTs induce profibrogenic effects in mouse lung at 21 d postexposure, but there are no differences between tube lengths. In contrast, these SWCNTs demonstrate length-dependent antibacterial effects on Escherichia coli, with the long SWCNT exerting stronger effects than the medium or short tubes. These effects are reduced by Pluronic F108 coating or supplementing with glucose. The data show length-dependent effects on proinflammatory response in macrophage cell line and antibacterial effects, but not on collagen deposition in the lung. These data demonstrate that over the length scale tested, the biological response to highly purified SWCNTs is dependent on the complexity of the nano/bio interface.
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128
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Mannix AJ, Zhang Z, Guisinger NP, Yakobson BI, Hersam MC. Borophene as a prototype for synthetic 2D materials development. NATURE NANOTECHNOLOGY 2018; 13:444-450. [PMID: 29875501 DOI: 10.1038/s41565-018-0157-4] [Citation(s) in RCA: 167] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 04/25/2018] [Indexed: 05/09/2023]
Abstract
The synthesis of 2D materials with no analogous bulk layered allotropes promises a substantial breadth of physical and chemical properties through the diverse structural options afforded by substrate-dependent epitaxy. However, despite the joint theoretical and experimental efforts to guide materials discovery, successful demonstrations of synthetic 2D materials have been rare. The recent synthesis of 2D boron polymorphs (that is, borophene) provides a notable example of such success. In this Perspective, we discuss recent progress and future opportunities for borophene research. Borophene combines unique mechanical properties with anisotropic metallicity, which complements the canon of conventional 2D materials. The multi-centre characteristics of boron-boron bonding lead to the formation of configurationally varied, vacancy-mediated structural motifs, providing unprecedented diversity in a mono-elemental 2D system with potential for electronic applications, chemical functionalization, materials synthesis and complex heterostructures. With its foundations in computationally guided synthesis, borophene can serve as a prototype for ongoing efforts to discover and exploit synthetic 2D materials.
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129
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Zhong C, Sangwan VK, Wang C, Bergeron H, Hersam MC, Weiss EA. Mechanisms of Ultrafast Charge Separation in a PTB7/Monolayer MoS 2 van der Waals Heterojunction. J Phys Chem Lett 2018; 9:2484-2491. [PMID: 29688016 DOI: 10.1021/acs.jpclett.8b00628] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mixed-dimensional van der Waals heterojunctions comprising polymer and two-dimensional (2D) semiconductors have many characteristics of an ideal charge separation interface for optoelectronic and photonic applications. However, the photoelectron dynamics at polymer-2D semiconductor heterojunction interfaces are currently not sufficiently understood to guide the optimization of devices for these applications. This Letter reports a systematic exploration of the time-dependent photophysical processes that occur upon photoexcitation of a type-II heterojunction between the polymer PTB7 and monolayer MoS2. In particular, photoinduced electron transfer from PTB7 to electronically hot states of MoS2 occurs in less than 250 fs. This process is followed by a 1-5 ps exciton diffusion-limited electron transfer from PTB7 to MoS2 and a sub-3 ps photoinduced hole transfer from MoS2 to PTB7. The equilibrium between excitons and polaron pairs in PTB7 determines the charge separation yield, whereas the 3-4 ns lifetime of photogenerated carriers is probably limited by MoS2 defects.
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130
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Hu G, Kang J, Ng LWT, Zhu X, Howe RCT, Jones CG, Hersam MC, Hasan T. Functional inks and printing of two-dimensional materials. Chem Soc Rev 2018; 47:3265-3300. [PMID: 29667676 DOI: 10.1039/c8cs00084k] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Graphene and related two-dimensional materials provide an ideal platform for next generation disruptive technologies and applications. Exploiting these solution-processed two-dimensional materials in printing can accelerate this development by allowing additive patterning on both rigid and conformable substrates for flexible device design and large-scale, high-speed, cost-effective manufacturing. In this review, we summarise the current progress on ink formulation of two-dimensional materials and the printable applications enabled by them. We also present our perspectives on their research and technological future prospects.
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131
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Henning A, Sangwan VK, Bergeron H, Balla I, Sun Z, Hersam MC, Lauhon LJ. Charge Separation at Mixed-Dimensional Single and Multilayer MoS 2/Silicon Nanowire Heterojunctions. ACS APPLIED MATERIALS & INTERFACES 2018; 10:16760-16767. [PMID: 29682958 DOI: 10.1021/acsami.8b03133] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Layered two-dimensional (2-D) semiconductors can be combined with other low-dimensional semiconductors to form nonplanar mixed-dimensional van der Waals (vdW) heterojunctions whose charge transport behavior is influenced by the heterojunction geometry, providing a new degree of freedom to engineer device functions. Toward that end, we investigated the photoresponse of Si nanowire/MoS2 heterojunction diodes with scanning photocurrent microscopy and time-resolved photocurrent measurements. Comparison of n-Si/MoS2 isotype heterojunctions with p-Si/MoS2 heterojunction diodes under varying biases shows that the depletion region in the p-n heterojunction promotes exciton dissociation and carrier collection. We measure an instrument-limited response time of 1 μs, which is 10 times faster than the previously reported response times for planar Si/MoS2 devices, highlighting the advantages of the 1-D/2-D heterojunction. Finite element simulations of device models provide a detailed understanding of how the electrostatics affect charge transport in nanowire/vdW heterojunctions and inform the design of future vdW heterojunction photodetectors and transistors.
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132
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Campbell GP, Mannix AJ, Emery JD, Lee TL, Guisinger NP, Hersam MC, Bedzyk MJ. Resolving the Chemically Discrete Structure of Synthetic Borophene Polymorphs. NANO LETTERS 2018; 18:2816-2821. [PMID: 29653052 DOI: 10.1021/acs.nanolett.7b05178] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Atomically thin two-dimensional (2D) materials exhibit superlative properties dictated by their intralayer atomic structure, which is typically derived from a limited number of thermodynamically stable bulk layered crystals (e.g., graphene from graphite). The growth of entirely synthetic 2D crystals, those with no corresponding bulk allotrope, would circumvent this dependence upon bulk thermodynamics and substantially expand the phase space available for structure-property engineering of 2D materials. However, it remains unclear if synthetic 2D materials can exist as structurally and chemically distinct layers anchored by van der Waals (vdW) forces, as opposed to strongly bound adlayers. Here, we show that atomically thin sheets of boron (i.e., borophene) grown on the Ag(111) surface exhibit a vdW-like structure without a corresponding bulk allotrope. Using X-ray standing wave-excited X-ray photoelectron spectroscopy, the positions of boron in multiple chemical states are resolved with sub-angström spatial resolution, revealing that the borophene forms a single planar layer that is 2.4 Å above the unreconstructed Ag surface. Moreover, our results reveal that multiple borophene phases exhibit these characteristics, denoting a unique form of polymorphism consistent with recent predictions. This observation of synthetic borophene as chemically discrete from the growth substrate suggests that it is possible to engineer a much wider variety of 2D materials than those accessible through bulk layered crystal structures.
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133
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Naik AR, Kim JJ, Usluer Ö, Gonzalez Arellano DL, Secor EB, Facchetti A, Hersam MC, Briseno AL, Watkins JJ. Direct Printing of Graphene Electrodes for High-Performance Organic Inverters. ACS APPLIED MATERIALS & INTERFACES 2018; 10:15988-15995. [PMID: 29667396 DOI: 10.1021/acsami.8b01302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Scalable fabrication of high-resolution electrodes and interconnects is necessary to enable advanced, high-performance, printed, and flexible electronics. Here, we demonstrate the direct printing of graphene patterns with feature widths from 300 μm to ∼310 nm by liquid-bridge-mediated nanotransfer molding. This solution-based technique enables residue-free printing of graphene patterns on a variety of substrates with surface energies between ∼43 and 73 mN m-1. Using printed graphene source and drain electrodes, high-performance organic field-effect transistors (OFETs) are fabricated with single-crystal rubrene (p-type) and fluorocarbon-substituted dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDIF-CN2) (n-type) semiconductors. Measured mobilities range from 2.1 to 0.2 cm2 V-1 s-1 for rubrene and from 0.6 to 0.1 cm2 V-1 s-1 for PDIF-CN2. Complementary inverter circuits are fabricated from these single-crystal OFETs with gains as high as ∼50. Finally, these high-resolution graphene patterns are compatible with scalable processing, offering compelling opportunities for inexpensive printed electronics with increased performance and integration density.
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134
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Parak WJ, Chan WWC, Chhowalla M, Farokhzad O, Glotzer S, Gogotsi Y, Hammond PT, Hersam MC, Javey A, Kagan CR, Kataoka K, Khademhosseini A, Kotov NA, Lee ST, Lee YH, Li Y, Millstone J, Mulvaney PA, Nel AE, Nordlander PJ, Penner RM, Rogach AL, Schaak RE, Stevens MM, Wee ATS, Willson CG, Weiss PS. Helmuth Möhwald (1946-2018). ACS NANO 2018; 12:3053-3055. [PMID: 29676563 DOI: 10.1021/acsnano.8b02755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
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135
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Nguyen D, Kang G, Chiang N, Chen X, Seideman T, Hersam MC, Schatz GC, Van Duyne RP. Probing Molecular-Scale Catalytic Interactions between Oxygen and Cobalt Phthalocyanine Using Tip-Enhanced Raman Spectroscopy. J Am Chem Soc 2018; 140:5948-5954. [DOI: 10.1021/jacs.8b01154] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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136
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137
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Wu Y, Bobbitt NS, Logsdon JL, Powers‐Riggs NE, Nelson JN, Liu X, Wang TC, Snurr RQ, Hupp JT, Farha OK, Hersam MC, Wasielewski MR. Tunable Crystallinity and Charge Transfer in Two‐Dimensional G‐Quadruplex Organic Frameworks. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201800230] [Citation(s) in RCA: 9] [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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138
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Wu Y, Bobbitt NS, Logsdon JL, Powers‐Riggs NE, Nelson JN, Liu X, Wang TC, Snurr RQ, Hupp JT, Farha OK, Hersam MC, Wasielewski MR. Tunable Crystallinity and Charge Transfer in Two‐Dimensional G‐Quadruplex Organic Frameworks. Angew Chem Int Ed Engl 2018; 57:3985-3989. [DOI: 10.1002/anie.201800230] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Indexed: 11/10/2022]
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139
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Li R, Guiney LM, Chang CH, Mansukhani ND, Ji Z, Wang X, Liao YP, Jiang W, Sun B, Hersam MC, Nel AE, Xia T. Surface Oxidation of Graphene Oxide Determines Membrane Damage, Lipid Peroxidation, and Cytotoxicity in Macrophages in a Pulmonary Toxicity Model. ACS NANO 2018; 12:1390-1402. [PMID: 29328670 PMCID: PMC5834379 DOI: 10.1021/acsnano.7b07737] [Citation(s) in RCA: 160] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
While two-dimensional graphene oxide (GO) is used increasingly in biomedical applications, there is uncertainty on how specific physicochemical properties relate to biocompatibility in mammalian systems. Although properties such as lateral size and the colloidal properties of the nanosheets are important, the specific material properties that we address here is the oxidation state and reactive surface groups on the planar surface. In this study, we used a GO library, comprising pristine, reduced (rGO), and hydrated GO (hGO), in which quantitative assessment of the hydroxyl, carboxyl, epoxy, and carbon radical contents was used to study the impact on epithelial cells and macrophages, as well as in the murine lung. Strikingly, we observed that hGO, which exhibits the highest carbon radical density, was responsible for the generation of cell death in THP-1 and BEAS-2B cells as a consequence of lipid peroxidation of the surface membrane, membrane lysis, and cell death. In contrast, pristine GO had lesser effects, while rGO showed extensive cellular uptake with minimal effects on viability. In order to see how these in vitro effects relate to adverse outcomes in the lung, mice were exposed to GOs by oropharyngeal aspiration. Animal sacrifice after 40 h demonstrated that hGO was more prone than other materials to generate acute lung inflammation, accompanied by the highest lipid peroxidation in alveolar macrophages, cytokine production (LIX, MCP-1), and LDH release in bronchoalveolar lavage fluid. Pristine GO showed less toxicity, whereas rGO had minimal effects. We demonstrate that the surface oxidation state and carbon radical content play major roles in the induction of toxicity by GO in mammalian cells and the lung.
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140
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Peng L, Wells SA, Ryder CR, Hersam MC, Grayson M. All-Electrical Determination of Crystal Orientation in Anisotropic Two-Dimensional Materials. PHYSICAL REVIEW LETTERS 2018. [PMID: 29542991 DOI: 10.1103/physrevlett.120.086801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The crystal orientation of an exfoliated black phosphorous flake is determined by purely electrical means. A sequence of three resistance measurements on an arbitrarily shaped flake with five contacts determines the three independent components of the anisotropic in-plane resistivity tensor, thereby revealing the crystal axes. The resistivity anisotropy ratio decreases linearly with increasing temperature T and carrier density reaching a maximum ratio of 3.0 at low temperatures and densities, while mobility indicates impurity scattering at low T and acoustic phonon scattering at high T.
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141
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Sangwan VK, Lee HS, Bergeron H, Balla I, Beck ME, Chen KS, Hersam MC. Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide. Nature 2018; 554:500-504. [DOI: 10.1038/nature25747] [Citation(s) in RCA: 494] [Impact Index Per Article: 82.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 12/19/2017] [Indexed: 12/22/2022]
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142
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Zeng L, Turrisi R, Fu B, Emery JD, Walker AR, Ratner MA, Hersam MC, Facchetti AF, Marks TJ, Bedzyk MJ. Measuring Dipole Inversion in Self-Assembled Nano-Dielectric Molecular Layers. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6484-6490. [PMID: 29378110 DOI: 10.1021/acsami.7b16160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A self-assembled nanodielectric (SAND) is an ultrathin film, typically with periodic layer pairs of high-k oxide and phosphonic-acid-based π-electron (PAE) molecular layers. IPAE, having a molecular structure similar to that of PAE but with an inverted dipole direction, has recently been developed for use in thin-film transistors. Here we report that replacing PAE with IPAE in SAND-based thin-film transistors induces sizable threshold and turn-on voltage shifts, indicating the flipping of the built-in SAND polarity. The bromide counteranion (Br-) associated with the cationic stilbazolium portion of PAE or IPAE is of great importance, because its relative position strongly affects the electric dipole moment of the organic layer. Hence, a set of X-ray synchrotron measurements were designed and performed to directly measure and compare the Br- distributions within the PAE and IPAE SANDs. Two trilayer SANDs, consisting of a PAE or IPAE layer sandwiched between an HfOx and a ZrOx layer, were deposited on the SiOx surface of Si substrates or periodic Si/Mo multilayer substrates for X-ray reflectivity and X-ray standing wave measurements, respectively. Along with complementary DFT simulations, the spacings, elemental (Hf, Br, and Zr) distributions, molecular orientations, and Mulliken charge distributions of the PAE and IPAE molecules within each of the SAND trilayers were determined and correlated with the dipole inversion.
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143
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Sangwan VK, Beck ME, Henning A, Luo J, Bergeron H, Kang J, Balla I, Inbar H, Lauhon LJ, Hersam MC. Self-Aligned van der Waals Heterojunction Diodes and Transistors. NANO LETTERS 2018; 18:1421-1427. [PMID: 29385342 DOI: 10.1021/acs.nanolett.7b05177] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A general self-aligned fabrication scheme is reported here for a diverse class of electronic devices based on van der Waals materials and heterojunctions. In particular, self-alignment enables the fabrication of source-gated transistors in monolayer MoS2 with near-ideal current saturation characteristics and channel lengths down to 135 nm. Furthermore, self-alignment of van der Waals p-n heterojunction diodes achieves complete electrostatic control of both the p-type and n-type constituent semiconductors in a dual-gated geometry, resulting in gate-tunable mean and variance of antiambipolar Gaussian characteristics. Through finite-element device simulations, the operating principles of source-gated transistors and dual-gated antiambipolar devices are elucidated, thus providing design rules for additional devices that employ self-aligned geometries. For example, the versatility of this scheme is demonstrated via contact-doped MoS2 homojunction diodes and mixed-dimensional heterojunctions based on organic semiconductors. The scalability of this approach is also shown by fabricating self-aligned short-channel transistors with subdiffraction channel lengths in the range of 150-800 nm using photolithography on large-area MoS2 films grown by chemical vapor deposition. Overall, this self-aligned fabrication method represents an important step toward the scalable integration of van der Waals heterojunction devices into more sophisticated circuits and systems.
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144
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Liu H, Li Q, Yao Z, Li L, Li Y, Wolverton C, Hersam MC, Wu J, Dravid VP. Origin of Fracture-Resistance to Large Volume Change in Cu-Substituted Co 3 O 4 Electrodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:1704851. [PMID: 29210479 DOI: 10.1002/adma.201704851] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/29/2017] [Indexed: 06/07/2023]
Abstract
The electrode materials conducive to conversion reactions undergo large volume change in cycles which restrict their further development. It has been demonstrated that incorporation of a third element into metal oxides can improve the cycling stability while the mechanism remains unknown. Here, an in situ and ex situ electron microscopy investigation of structural evolutions of Cu-substituted Co3 O4 supplemented by first-principles calculations is reported to reveal the mechanism. An interconnected framework of ultrathin metallic copper formed provides a high conductivity backbone and cohesive support to accommodate the volume change and has a cube-on-cube orientation relationship with Li2 O. In charge, a portion of Cu metal is oxidized to CuO, which maintains a cube-on-cube orientation relationship with Cu. The Co metal and oxides remain as nanoclusters (less than 5 nm) thus active in subsequent cycles. This adaptive architecture accommodates the formation of Li2 O in the discharge cycle and underpins the catalytic activity of Li2 O decomposition in the charge cycle.
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145
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Chiang N, Jiang N, Madison LR, Pozzi EA, Wasielewski MR, Ratner MA, Hersam MC, Seideman T, Schatz GC, Van Duyne RP. Probing Intermolecular Vibrational Symmetry Breaking in Self-Assembled Monolayers with Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy. J Am Chem Soc 2017; 139:18664-18669. [PMID: 29198112 DOI: 10.1021/jacs.7b10645] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS) combines the atomic-scale imaging capability of scanning probe microscopy with the single-molecule chemical sensitivity and structural specificity of surface-enhanced Raman spectroscopy. Here, we use these techniques in combination with theory to reveal insights into the influence of intermolecular interactions on the vibrational spectra of a N-N'-bis(2,6-diisopropylphenyl)-perylene-3,4:9,10-bis(dicarboximide) (PDI) self-assembled monolayer adsorbed on single-crystal Ag substrates at room temperature. In particular, we have revealed the lifting of a vibrational degeneracy of a mode of PDI on Ag(111) and Ag(100) surfaces, with the most strongly perturbed mode being that associated with the largest vibrational amplitude on the periphery of the molecule. This work demonstrates that UHV-TERS enables direct measurement of molecule-molecule interaction at nanoscale. We anticipate that this information will advance the fundamental understanding of the most important effect of intermolecular interactions on the vibrational modes of surface-bound molecules.
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146
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Mansukhani ND, Guiney LM, Wei Z, Roth EW, Putz KW, Luijten E, Hersam MC. Optothermally Reversible Carbon Nanotube-DNA Supramolecular Hybrid Hydrogels. Macromol Rapid Commun 2017; 39. [PMID: 29065239 DOI: 10.1002/marc.201700587] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Indexed: 11/09/2022]
Abstract
Supramolecular hydrogels (SMHs) are three-dimensional constructs wherein the majority of the volume is occupied by water. Since the bonding forces between the components of SMHs are noncovalent, SMH properties are often tunable, stimuli-responsive, and reversible, which enables applications including triggered drug release, sensing, and tissue engineering. Meanwhile, single-walled carbon nanotubes (SWCNTs) possess superlative electrical and thermal conductivities, high mechanical strength, and strong optical absorption at near-infrared wavelengths that have the potential to add unique functionality to SMHs. However, SWCNT-based SMHs have thus far not realized the potential of the optical properties of SWCNTs to enable reversible response to near-infrared irradiation. Here, we present a novel SMH architecture comprised solely of DNA and SWCNTs, wherein noncovalent interactions provide structural integrity without compromising the intrinsic properties of SWCNTs. The mechanical properties of these SMHs are readily tuned by varying the relative concentrations of DNA and SWCNTs, which varies the cross-linking density as shown by molecular dynamics simulations. Moreover, the SMH gelation transition is fully reversible and can be triggered by a change in temperature or near-infrared irradiation. This work explores a new regime for SMHs with potential utility for a range of applications including sensors, actuators, responsive substrates, and 3D printing.
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147
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Secor EB, Gao TZ, Dos Santos MH, Wallace SG, Putz KW, Hersam MC. Combustion-Assisted Photonic Annealing of Printable Graphene Inks via Exothermic Binders. ACS APPLIED MATERIALS & INTERFACES 2017; 9:29418-29423. [PMID: 28820238 DOI: 10.1021/acsami.7b07189] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
High-throughput and low-temperature processing of high-performance nanomaterial inks is an important technical challenge for large-area, flexible printed electronics. In this report, we demonstrate nitrocellulose as an exothermic binder for photonic annealing of conductive graphene inks, leveraging the rapid decomposition kinetics and built-in energy of nitrocellulose to enable versatile process integration. This strategy results in superlative electrical properties that are comparable to extended thermal annealing at 350 °C, using a pulsed light process that is compatible with thermally sensitive substrates. The resulting porous microstructure and broad liquid-phase patterning compatibility are exploited for printed graphene microsupercapacitors on paper-based substrates.
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148
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Jang H, Ryder CR, Wood JD, Hersam MC, Cahill DG. 3D Anisotropic Thermal Conductivity of Exfoliated Rhenium Disulfide. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1700650. [PMID: 28722239 DOI: 10.1002/adma.201700650] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/30/2017] [Indexed: 06/07/2023]
Abstract
ReS2 represents a different class of 2D materials, which is characterized by low symmetry having 1D metallic chains within the planes and extremely weak interlayer bonding. Here, the thermal conductivity of single-crystalline ReS2 in a distorted 1T phase is determined at room temperature for the in-plane directions parallel and perpendicular to the Re-chains, and the through-plane direction using time-domain thermoreflectance. ReS2 is prepared in the form of flakes having thicknesses of 60-450 nm by micromechanical exfoliation, and their crystalline orientations are identified by polarized Raman spectroscopy. The in-plane thermal conductivity is higher along the Re-chains, (70 ± 18) W m-1 K-1 , as compared to transverse to the chains, (50 ± 13) W m-1 K-1 . As expected from the weak interlayer bonding, the through-plane thermal conductivity is the lowest observed to date for 2D materials, (0.55 ± 0.07) W m-1 K-1 , resulting in a remarkably high anisotropy of (130 ± 40) and (90 ± 30) for the two in-plane directions. The thermal conductivity and interface thermal conductance of ReS2 are discussed relative to the other 2D materials.
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Chan WCW, Chhowalla M, Glotzer S, Gogotsi Y, Hafner JH, Hammond PT, Hersam MC, Javey A, Kagan CR, Kataoka K, Khademhosseini A, Kotov NA, Lee ST, Li Y, Möhwald H, Mulvaney P, Nel AE, Nordlander PJ, Parak WJ, Penner RM, Rogach AL, Schaak RE, Stevens MM, Wee ATS, Willson CG, Fernandez LE, Weiss PS. Our First and Next Decades at ACS Nano. ACS NANO 2017; 11:7553-7555. [PMID: 28830059 DOI: 10.1021/acsnano.7b05765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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Li Y, Buriak JM, Gogotsi Y, Hersam MC, Kagan CR, Weiss PS. Correction to "Prof. Millie Dresselhaus (1930-2017), Carbon Nanomaterials Pioneer". ACS NANO 2017; 11:8529. [PMID: 28776983 DOI: 10.1021/acsnano.7b05372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
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