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arXiv 2021年

作者： Zhang, Yu-Tian Wang, Yun-Peng Zhang, Xianli Zhang, Yu-Yang Du, Shixuan Pantelides, Sokrates T. University of Chinese Academy of Sciences Institute of Physics Chinese Academy of Sciences Beijing100049 China Hunan Key Laboratory for Super Microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha410083 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100049 China Songshan Lake Materials Laboratory Guangdong Dongguan523808 China Department of Physics and Astronomy Department of Electrical and Computer Engineering Vanderbilt University NashvilleTN37235 United States

The structure of amorphous materials has been debated since the 1930’s as a binary question: amorphous materials are either Zachariasen continuous random networks (Z-CRNs) or Z-CRNs containing crystallites. It was recently demonstrated, however, that amorphous diamond can be synthesized in either form. Here we address the question of the structure of single-atom-thick amorphous monolayers. We reanalyze the results of prior simulations for amorphous graphene and report kinetic Monte Carlo simulations based on alternative algorithms. We find that crystallite-containing Z-CRN is the favored structure of elemental amorphous graphene, as recently fabricated, whereas the most likely structure of binary monolayer amorphous BN is altogether different than either of the two long-debated options: it is a compositionally disordered "pseudo-CRN" comprising a mix of B-N and noncanonical B-B and N-N bonds and containing "pseudocrystallites", namely honeycomb regions made of noncanonical hexagons. Implications for other non-elemental 2D and bulk amorphous materials are discussed. © 2021, CC BY-NC-SA.

关键词： Crystallites

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Synthesis and properties of free-standing monolayer amorphous carbon

arXiv

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arXiv 2021年

作者： Toh, Chee-Tat Zhang, Hongji Lin, Junhao Mayorov, Alexander S. Wang, Yun-Peng Orofeo, Carlo Ferry, Darim Badur Andersen, Henrik Kakenov, Nurbek Guo, Zenglong Abidi, Irfan Haider Sims, Hunter Suenaga, Kazu Pantelides, Sokrates T. Özyilmaz, Barbaros Department of Physics National University of Singapore Singapore117551 Singapore Centre for Advanced 2D Materials National University of Singapore Singapore117546 Singapore Department of Materials Science and Engineering National University of Singapore Singapore117575 Singapore National Institute of Advanced Industrial Science and Technology Tsukuba Japan Department of Physics Southern University of Science and Technology Shenzhen518055 China Department of Physics and Astronomy Vanderbilt University NashvilleTN37235 United States Hunan Key Laboratory for Super-Microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha Hunan410083 China Department of Mechanical Engineering University of Tokyo Japan Department of Electrical Engineering and Computer Science Vanderbilt University NashvilleTN37235 United States

Bulk amorphous materials have been studied extensively and are used widely. Yet, their atomic arrangement remains an open issue. They are generally believed to be Zachariasen continuous random networks (Z-CRNs)1, but recent experimental evidence favours the competing crystallite model in the case of amorphous silicon2–4. Corresponding questions in 2D materials are wide open. Here we report the synthesis of centimetre-scale, freestanding, continuous, and stable monolayer amorphous carbon (MAC), topologically distinct from disordered graphene, by laser-assisted chemical vapour deposition5. Unlike bulk materials, the amorphous structure of MAC can be determined by atomic-resolution imaging. Extensive characterisation reveals complete absence of long-range periodicity and a threefold-coordinated structure with a wide distribution of bond lengths, bond angles, and 5-, 6-, 7-, and 8-member rings. The ring distribution is not a Z-CRN but resembles the competing (nano)crystallite model6. A corresponding model has been constructed and enables density-functional-theory calculations of MAC properties, in accord with observations. Direct measurements confirm that it is insulating with resistivity values similar to CVD grown boron nitride. Freestanding MAC is surprisingly stable and deforms to a high breaking strength, without crack propagation from the point of fracture. The present work reveals a stable, freestanding MAC with excellent physical properties, potentially leading to unique applications. © 2021, CC BY-NC-ND.

关键词： Monolayers

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A chlorinated copolymer donor demonstrates a 18.13% power conversion efficiency

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Journal of Semiconductors 2021年第1期42卷 11-15,16-23页

作者： Jianqiang Qin Lixiu Zhang Chuantian Zuo Zuo Xiao Yongbo Yuan Shangfeng Yang Feng Hao Ming Cheng Kuan Sun Qinye Bao Zhengyang Bin Zhiwen Jin and Liming Ding Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China Key Laboratory of Low-grade Energy Utilization Technologies and Systems(MOE) School of Energy and Power EngineeringChongqing UniversityChongqing 400044China Hunan Key Laboratory of Super Microstructure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China Department of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731China Institute for Energy Research Jiangsu UniversityZhenjiang 212013China Key Laboratory of Polar Materials and Devices(MoE) School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China College of Chemistry Sichuan UniversityChengdu 610064China School of Physical Science and Technology Lanzhou UniversityLanzhou 730000China

The rapid development of low-bandgap(LBG)nonfullerene acceptors and wide-bandgap(WBG)copolymer donors in recent years has boosted the power conversion efficiency(PCE)of organic solar cells(OSCs)to the 18%level[1−21].The commercialization of OSCs is highly ***,critical issues like the cost and the stability also determine whether OSCs can enter the market or not[22].

关键词： copolymer donor stability

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Topologically nontrivial and trivial zero modes in chiral molecules

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Physical Review B 2023年第3期108卷 035401-035401页

作者： Xiao-Feng Chen Wenchen Luo Tie-Feng Fang Yossi Paltiel Oded Millo Ai-Min Guo Qing-Feng Sun Hunan Key Laboratory for Super-microstructure and Ultrafast Process School of Physics and Electronics Central South University Changsha 410083 China School of Physical Science and Technology Lanzhou University Lanzhou 730000 China School of Sciences Nantong University Nantong 226019 China Applied Physics Department and the Centre for Nanoscience and Nanotechnology The Hebrew University of Jerusalem 91904 Jerusalem Israel Racah Institute of Physics and the Centre for Nanoscience and Nanotechnology The Hebrew University of Jerusalem 91904 Jerusalem Israel International Center for Quantum Materials School of Physics Peking University Beijing 100871 China Hefei National Laboratory Hefei 230088 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

Recently, electron transport along chiral molecules has been attracting extensive interest and a number of intriguing phenomena have been reported in recent experiments, such as the emergence of zero-bias conductance peaks in the transmission spectrum upon the adsorption of single-helical protein on superconducting films. Here, we present a theoretical study of electron transport through a two-terminal single-helical protein sandwiched between a superconducting electrode and a normal-metal one in the presence of a perpendicular magnetic field. As the proximity-induced superconductivity attenuates with the distance from superconducting media, the pairing potential along the helix axis of the single-helical protein is expected to decrease exponentially, which is characterized by the decay exponent λ and closely related to the experiments. Our results indicate that (i) a zero-bias conductance peak of 2e2/h appears at zero temperature and the peak height (width) decreases (broadens) with increasing temperature, and (ii) this zero-bias peak can split into two peaks, which are in agreement with the experiments [see, e.g., H. Alpern et al. Nano Lett. 19, 5167 (2019)]. Remarkably, Majorana zero modes are observed in this protein-superconductor setup in a wide range of model parameters, as manifested by the Z2 topological invariant and the Majorana oscillation. Interestingly, a specific region is demonstrated for decaying superconductivity, where topologically nontrivial and trivial zero modes coexist and the bandgap remains constant. With increasing the pairing potential, the topologically nontrivial zero modes will transform to the trivial ones without any bandgap closing-reopening, and the critical pairing potential of the phase transition attenuates exponentially with λ. Additionally, one of the two zero modes can be continuously shifted from one end of the protein toward the other end contacted by the normal-metal electrode. The underlying physics of the topologically n

关键词： Majorana bound states Proximity effect Topological phase transition Topological superconductors Transport phenomena Biomolecules

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Activating Layered Double Hydroxide with Multivacancies by Memory Effect for Energy-Efficient Hydrogen Production at Neutral pH

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ACS Energy Letters 2019年第6期4卷 1412-1418页

作者： Zijian Yuan Seong-Min Bak Pengsong Li Yin Jia Lirong Zheng Yu Zhou Lu Bai Enyuan Hu Xiao-Qing Yang Zhao Cai Yongming Sun Xiaoming Sun State Key Laboratory of Chemical Resource Engineering Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Beijing 100029 China Chemistry Division Brookhaven National Laboratory Upton New York 11973 United States Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China School of Physics and Electronics Hunan Key Laboratory for Super-Microstructure and Ultrafast Process Central South University Changsha 410083 China National Center for Nanoscience & Technology Beijing 100190 China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 China College of Energy Beijing University of Chemical Technology Beijing 100029 China

Sustainable water-splitting hydrogen production has long been considered one of the most promising energy conversion technologies, but enormous challenges remain: for instance, water electrolysis suffers from high overpotential and over energy consumption under neutral pH conditions. Here, taking advantage of the memory effect of layered double hydroxide (LDH), we report an energy-efficient neutral water electrolyzer material based on LDH with multiple vacancy defects. Benefiting from the improved electrical conductivity, larger electrochemical surface area (ECSA), and faster charge transfer, the NiFe LDH with O, Ni, and Fe vacancies exhibits a low overpotential of 87 mV at 10 mA/cm2for hydrogen evolution reaction (HER) in a pH 7 buffer electrolyte. Impressively, the as-fabricated vacancy-containing NiFe LDH (v-NiFe LDH) splits water with a current density of 10 mA/cm2at ∼1.60 V in a two-electrode device, outperforming most other water-splitting catalysts in neutral media. Such an electrolyzer setup could be powered by a commercial 2.0 V solar cell, producing hydrogen at a current density as high as 100 mA/cm2.

关键词： Inorganic compounds Circuits Defects in solids Evolution reactions materials

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Enhancement of electron transport and band gap opening in graphene induced by adsorbates

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Physical Review B 2020年第11期101卷 115417-115417页

作者： Lan Chen Fangping Ouyang Songshan Ma Tie-Feng Fang Ai-Min Guo Qing-Feng Sun School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast Process Central South University Changsha 410083 People's Republic of China Powder Metallurgy Research Institute and State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 People's Republic of China School of Physics and Technology Xinjiang University Urumqi 830046 People's Republic of China School of Physical Science and Technology Lanzhou University Lanzhou 730000 China International Center for Quantum Materials School of Physics Peking University Beijing 100871 China Collaborative Innovation Center of Quantum Matter Beijing 100871 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing 100190 China

Impurities are unavoidable during the preparation of graphene samples and play an important role in graphene's electronic properties when they are adsorbed on the graphene surface. In this work, we study the electronic structures and transport properties of a two-terminal zigzag graphene nanoribbon (ZGNR) device whose scattering region is covered by various adsorbates within the framework of the tight-binding approximation, by taking into account the coupling strength γ between adsorbates and carbon atoms, the adsorbate concentration ni, and the on-site energy disorder of adsorbates. Our results indicate that when the scattering region is fully covered by homogeneous adsorbates, i.e., ni=1, a transmission gap opens around the Dirac point and its width is almost proportional to γ2. In particular, two conductance plateaus of G=2e2/h appear in the vicinity of the electron energy E=±γ. When the scattering region is partially covered by homogeneous adsorbates (0

关键词： Anderson localization Band gap Quantum transport Graphene Landauer formula

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Pulsed Lasers: Pulsed Lasers Employing Solution‐processed Plasmonic Cu3−xP Colloidal Nanocrystals (Adv. Mater. 18/2016)

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advanced materials 2016年第18期28卷

作者： Zeke Liu Haoran Mu Si Xiao Rongbin Wang Zhiteng Wang Weiwei Wang Yongjie Wang Xiangxiang Zhu Kunyuan Lu Han Zhang Shuit‐Tong Lee Qiaoliang Bao Wanli Ma Institute of Functional Nano and Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon‐Based Functional Materials and Devices Soochow University Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University 199 Ren‐Ai Road Suzhou Industrial Park Suzhou Jiangsu 215123 China Institute of Super‐Microstructure and Ultrafast Process in Advanced Materials School of Physics and Electronics Hunan Key Laboratory for Super‐Microstructure and Ultrafast Process Central South University Changsha 410083 China SZU‐NUS Collaborative Innovation Center for Optoelectronic Science and Technology and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province College of Optoelectronic Engineering Shenzhen University Shenzhen 518060 China

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Enhancement of electron transport and bandgap opening in graphene induced by adsorbates

arXiv

引用

arXiv 2019年

作者： Chen, Lan Ouyang, Fangping Ma, Songshan Fang, Tie-Feng Guo, Ai-Min Sun, Qing-Feng School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast Process Central South University Changsha410083 China Powder Metallurgy Research Institute State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China School of Physics and Technology Xinjiang University Urumqi830046 China School of Physical Science and Technology Lanzhou University Lanzhou730000 China International Center for Quantum Materials School of Physics Peking University Beijing100871 China Collaborative Innovation Center of Quantum Matter Beijing100871 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China

Impurities are unavoidable during the preparation of graphene samples and play an important role in graphene’s electronic properties when they are adsorbed on graphene surface. In this work, we study the electronic structures and transport properties of a two-terminal zigzag graphene nanoribbon (ZGNR) device whose scattering region is covered by various adsorbates within the framework of the tight-binding approximation, by taking into account the coupling strength γ between adsorbates and carbon atoms, the adsorbate concentration ni, and the on-site energy disorder of adsorbates. Our results indicate that when the scattering region is fully covered by homogeneous adsorbates, i.e., ni = 1, a transmission gap opens around the Dirac point and its width is almost proportional to γ2. In particular, two conductance plateaus of G = 2e2/h appear in the vicinity of the electron energy E = ±γ. When the scattering region is partially covered by homogeneous adsorbates (0 Copyright © 2019, The Authors. All rights reserved.

关键词： Graphene

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Pulsed Lasers: Black Phosphorus–Polymer Composites for Pulsed Lasers (advanced Optical materials 10/2015)

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advanced Optical materials 2015年第10期3卷

作者： Haoran Mu Shenghuang Lin Zhongchi Wang Si Xiao Pengfei Li Yao Chen Han Zhang Haifeng Bao Shu Ping Lau Chunxu Pan Dianyuan Fan Qiaoliang Bao Institute of Functional Nano and Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou 215123 China Department of Applied Physics The Hong Kong Polytechnic University Hung Hom Hong Kong SAR 999077 China School of Physical and Technology Wuhan University Wuhan 430072 China Institute of Super-Microstructure and Ultrafast Process in Advanced Materials School of Physics and Electronics Hunan Key Laboratory for Super-Microstructure and Ultrafast Process Central South University Changsha 410083 China SZU-NUS Collaborative Innovation Centre for Optoelectronic Science & Technology and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province Shenzhen University Shenzhen 518060 China School of Materials Science and Engineering Wuhan Textile University Wuhan 430200 China

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Black arsenic: A layered semiconductor with extreme in-plane anisotropy

arXiv

引用

arXiv 2018年

作者： Chen, Yabin Chen, Chaoyu Kealhofer, Robert Liu, Huili Yuan, Zhiquan Jiang, Lili Suh, Joonki Park, Joonsuk Ko, Changhyun Choe, Hwan Sung Avila, José Zhong, Mianzeng Wei, Zhongming Li, Jingbo Li, Shushen Gao, Hongjun Liu, Yunqi Analytis, James Xia, Qinglin Asensio, Maria C. Wu, Junqiao Department of Materials Science and Engineering University of California BerkeleyCA94720 United States ANTARES Beamline Synchrotron SOLEIL Universite Paris-Saclay L’Orme des Merisiers Saint Aubin-BP 48 Gif sur Yvette Cedex91192 France Department of Physics University of California BerkeleyCA94720 United States Materials Sciences Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Institute of Physics University of Chinese Academy of Sciences Chinese Academy of Sciences Beijing100190 China Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing100190 China Department of Materials Science and Engineering Stanford University StanfordCA94305 United States State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing100083 China School of Physics and Electronics Hunan Key Laboratory for Super-microstructure and Ultrafast Process Central South University Changsha410083 China

Two-dimensional (2D) layered materials emerge in recent years as a new platform to host novel electronic, optical or excitonic physics and develop unprecedented nanoelectronic and energy applications.[1-5] By definition, these materials are strongly anisotropic between within the basal plane and cross the plane. The structural and property anisotropies inside their basal plane[6-9] however, are much less investigated. Herein, we report a rare chemical form of arsenic, called black-arsenic (b-As), as an extremely anisotropic layered semiconductor. We have performed systematic characterization on the structural, electronic, thermal and electrical properties of b-As single crystals, with particular focus on its anisotropies along two in-plane principle axes, armchair (AC) and zigzag (ZZ). Our analysis shows that b-As exhibits higher or comparable electronic, thermal and electric transport anisotropies between the AC and ZZ directions than any other known 2D crystals. Such extreme in-plane anisotropies are able to potentially implement novel ideas for scientific research and device applications. When occurring at the centre of Brillouin zone, electronic band extrema (conduction band minimum (CBM) or valence band maximum (VBM)) of cubic semiconductors are mostly isotropic. Namely, their dispersion exhibits the same curvature at very small wavevectors along different lattice directions. Anisotropic bands are typically a result of anisotropic crystal structure in the long range, because in the long-wavelength limit, short-range discreteness of the lattice is averaged out. Such lattice anisotropy could lead to highly anisotropic physical properties such as electric conductivity and phonon group velocity. Meanwhile, anisotropies in physical properties may lead to unusual device applications that are not possible in isotropic materials. In the recent revival of research in black phosphorus (b-P) as a 2D semiconductor with high charge carrier mobilities, anisotropies were foun

关键词： Anisotropy

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