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Vinod K. Sangwan Sonal V. Rangnekar Joohoon Kang Jianan Shen Hong-Sub Lee David Lam Junhua Shen Xiaolong Liu Ana C. M. de Moraes Lidia Kuo Jie Gu Haihua Wang Mark C. Hersam 《Advanced functional materials》2021,31(52):2107385
Memristive systems present a low-power alternative to silicon-based electronics for neuromorphic and in-memory computation. 2D materials have been increasingly explored for memristive applications due to their novel biomimetic functions, ultrathin geometry for ultimate scaling limits, and potential for fabricating large-area, flexible, and printed neuromorphic devices. While the switching mechanism in memristors based on single 2D nanosheets is similar to conventional oxide memristors, the switching mechanism in nanosheet composite films is complicated by the interplay of multiple physical processes and the inaccessibility of the active area in a two-terminal vertical geometry. Here, the authors report thermally activated memristors fabricated from percolating networks of diverse solution-processed 2D semiconductors including MoS2, ReS2, WS2, and InSe. The mechanisms underlying threshold switching and negative differential resistance are elucidated by designing large-area lateral memristors that allow the direct observation of filament and dendrite formation using in situ spatially resolved optical, chemical, and thermal analyses. The high switching ratios (up to 103) that are achieved at low fields (≈4 kV cm−1) are explained by thermally assisted electrical discharge that preferentially occurs at the sharp edges of 2D nanosheets. Overall, this work establishes percolating networks of solution-processed 2D semiconductors as a platform for neuromorphic architectures. 相似文献
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Yao Chen Wei Huang Vinod K. Sangwan Binghao Wang Li Zeng Gang Wang Yan Huang Zhiyun Lu Michael J. Bedzyk Mark C. Hersam Tobin J. Marks Antonio Facchetti 《Advanced materials (Deerfield Beach, Fla.)》2019,31(4)
High‐performance solution‐processed metal oxide (MO) thin‐film transistors (TFTs) are realized by fabricating a homojunction of indium oxide (In2O3) and polyethylenimine (PEI)‐doped In2O3 (In2O3:x% PEI, x = 0.5–4.0 wt%) as the channel layer. A two‐dimensional electron gas (2DEG) is thereby achieved by creating a band offset between the In2O3 and PEI‐In2O3 via work function tuning of the In2O3:x% PEI, from 4.00 to 3.62 eV as the PEI content is increased from 0.0 (pristine In2O3) to 4.0 wt%, respectively. The resulting devices achieve electron mobilities greater than 10 cm2 V?1 s?1 on a 300 nm SiO2 gate dielectric. Importantly, these metrics exceed those of the devices composed of the pristine In2O3 materials, which achieve a maximum mobility of ≈4 cm2 V?1 s?1. Furthermore, a mobility as high as 30 cm2 V?1 s?1 is achieved on a high‐k ZrO2 dielectric in the homojunction devices. This is the first demonstration of 2DEG‐based homojunction oxide TFTs via band offset achieved by simple polymer doping of the same MO material. 相似文献
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Progress towards monodisperse single-walled carbon nanotubes 总被引：1，自引：0，他引：1
Hersam MC 《Nature nanotechnology》2008,3(7):387-394
The defining characteristic of a nanomaterial is that its properties vary as a function of its size. This size dependence can be clearly observed in single-walled carbon nanotubes, where changes in structure at the atomic scale can modify the electronic and optical properties of these materials in a discontinuous manner (for example, changing metallic nanotubes to semiconducting nanotubes and vice versa). However, as most practical technologies require predictable and uniform performance, researchers have been aggressively seeking strategies for preparing samples of single-walled carbon nanotubes with well-defined diameters, lengths, chiralities and electronic properties (that is, uniformly metallic or uniformly semiconducting). This review highlights post-synthetic approaches for sorting single-walled carbon nanotubes - including selective chemistry, electrical breakdown, dielectrophoresis, chromatography and ultracentrifugation - and progress towards selective growth of monodisperse samples. 相似文献
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J.&#x;C. Stendahl E.&#x;R. Zubarev M.&#x;S. Arnold M.&#x;C. Hersam H.‐J. Sue S.&#x;I. Stupp 《Advanced functional materials》2005,15(3):487-493
We have previously reported that small quantities of self‐assembling molecules known as dendron rodcoils (DRCs) can be used as supramolecular additives to modify the properties of polystyrene (PS). These molecules spontaneously assemble into supramolecular nanoribbons that can be incorporated into bulk PS in such a way that the orientation of the polymer is significantly enhanced when mechanically drawn above the glass‐transition temperature. In the current study, we more closely evaluate the structural role of the DRC nanoribbons in PS by investigating the mechanical properties and deformation microstructures of polymers modified by self‐assembly. In comparision to PS homopolymer, PS containing small amounts (≤ 1.0 wt.‐%) of self‐assembling DRC molecules exhibit greater Charpy impact strengths in double‐notch four‐point bending and significantly greater elongations to failure in uniaxial tension at 250 % prestrain. Although the DRC‐modified polymer shows significantly smaller elongations to failure at 1000 % prestrain, both low‐ and high‐prestrain specimens maintain tensile strengths that are comparable to those of the homopolymer. The improved toughness and ductility of DRC‐modified PS appears to be related to the increased stress whitening and craze density that was observed near fracture surfaces. However, the mechanism by which the self‐assembling DRC molecules toughen PS is different from that of conventional additives. These molecules assemble into supramolecular nanoribbons that enhance polymer orientation, which in turn modifies crazing patterns and improves impact strength and ductility. 相似文献
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Alaboson JM Wang QH Kellar JA Park J Elam JW Pellin MJ Hersam MC 《Advanced materials (Deerfield Beach, Fla.)》2011,23(19):2181-2184
