作者机构：
[Chen, Changxin; Antaris, Alexander L.; Tao, Zhimin; Hong, Guosong; Wu, Di; Diao, Shuo; Wu, Justin Z.; Dai, Hongjie; Zhang, Xiaodong; Fukunaga, Chihiro; Zhang, Bo] Stanford Univ, Dept Chem, Stanford, CA 94305 USA.;[Yuan, Jun; Liu, Bo; Zou, Yingping] Cent S Univ, Coll Chem & Chem Engn, Changsha 410083, Hunan, Peoples R China.;[He, Yuehui; Liu, Bo; Zou, Yingping] Cent S Univ, State Key Lab Powder Met, Changsha 410083, Hunan, Peoples R China.;[Zou, Yingping] Cent S Univ, Sch Phys & Elect, Inst Super Microstruct & Ultrafast Proc Adv Mat, Changsha 410083, Hunan, Peoples R China.;[Cheng, Kai] Stanford Univ, Sch Med, Dept Radiol, Stanford, CA 94305 USA.
通讯机构：
[Zou, Yingping] Cent S Univ, Coll Chem & Chem Engn, Changsha 410083, Hunan, Peoples R China.
摘要：
In vivo fluorescence imaging in the second near-infrared window (1.0-1.7 mu m) can afford deep tissue penetration and high spatial resolution, owing to the reduced scattering of long-wavelength photons. Here we synthesize a series of low-bandgap donor/acceptor copolymers with tunable emission wavelengths of 1,050-1,350 nm in this window. Non-covalent functionalization with phospholipid-polyethylene glycol results in water-soluble and biocompatible polymeric nanoparticles, allowing for live cell molecular imaging at >1,000 nm with polymer fluorophores for the first time. Importantly, the high quantum yield of the polymer allows for in vivo, deep-tissue and ultrafast imaging of mouse arterial blood flow with an unprecedented frame rate of >25 frames per second. The high time-resolution results in spatially and time resolved imaging of the blood flow pattern in cardiogram waveform over a single cardiac cycle (similar to 200 ms) of a mouse, which has not been observed with fluorescence imaging in this window before.
摘要：
Graphene has attracted much interest in both academia and industry. The challenge of making it semiconducting is crucial for applications in electronic devices. A promising approach is to reduce its physical size down to the nanometer scale. Here, we present the surface-assisted bottom-up fabrication of atomically precise armchair graphene nanoribbons (AGNRs) with predefined widths, namely 7-, 14- and 21-AGNRs, on Ag(111) as well as their spatially resolved width-dependent electronic structures. STM/STS measurements reveal their associated electron scattering patterns and the energy gaps over 1 eV. The mechanism to form such AGNRs is addressed based on the observed intermediate products. Our results provide new insights into the local properties of AGNRs, and have implications for the understanding of their electrical properties and potential applications.
作者机构：
[Yuan, Yongbo; Huang, Jinsong; Shao, Yuchuan] Univ Nebraska, Dept Mech & Mat Engn, Lincoln, NE 68588 USA.;[Huang, Jinsong] Univ N Carolina, Dept Appl Phys Sci, Chapel Hill, NC 27599 USA.;[Yuan, Yongbo] Cent S Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Hunan, Peoples R China.;[Yan, Yanfa] Univ Toledo, Dept Phys & Astron, Toledo, OH 43606 USA.;[Yan, Yanfa] Univ Toledo, Wright Ctr Photovolta Innovat & Commercializat, Toledo, OH 43606 USA.
通讯机构：
[Huang, Jinsong] Univ Nebraska, Dept Mech & Mat Engn, Lincoln, NE 68588 USA.
摘要：
New photovoltaic materials have been searched for in the past decades for clean and renewable solar energy conversion with an objective of reducing the levelized cost of electricity (that is, the unit price of electricity over the course of the device lifetime). An emerging family of semiconductor materials - organic-inorganic halide perovskites (OIHPs) - are the focus of the photovoltaic research community owing to their use of low cost, nature-abundant raw materials, low-temperature and scalable solution fabrication processes, and, in particular, the very high power conversion efficiencies that have been achieved within the short time of their development. In this Review, we summarize and critically assess the most recent advances in understanding the physical properties of both 3D and low-dimensional OIHPs that favour a small open-circuit voltage deficit and high power conversion efficiency. Several prominent topics in this field on the unique properties of OIHPs are surveyed, including defect physics, ferroelectricity, exciton dissociation processes, carrier recombination lifetime and photon recycling. The impact of ion migration on solar cell efficiency and stability are also critically analysed. Finally, we discuss the remaining challenges in the commercialization of OIHP photovoltaics.
作者机构：
[Wang, Huishan; Wang, Haomin; Jiang, Mianheng; Wu, Tianru; Lu, Guangyuan; Xie, Xiaoming] Chinese Acad Sci, Shanghai Inst Microsyst & Informat Technol, State Key Lab Funct Mat Informat, Shanghai 200050, Peoples R China.;[Yuan, Qinghong] E China Normal Univ, Dept Phys, Shanghai 200241, Peoples R China.;[Wang, Huishan] Cent S Univ, Sch Phys & Elect, Changsha 410083, Hunan, Peoples R China.;[Ding, Feng] Hong Kong Polytech Univ, Inst Text & Clothing, Kowloon, Hong Kong, Peoples R China.;[Jiang, Mianheng; Xie, Xiaoming] Shanghai Tech Univ, Sch Phys Sci & Technol, Shanghai 200031, Peoples R China.
通讯机构：
[Xie, Xiaoming] Chinese Acad Sci, Shanghai Inst Microsyst & Informat Technol, State Key Lab Funct Mat Informat, 865 Changning Rd, Shanghai 200050, Peoples R China.
摘要：
Hexagonal boron nitride (h-BN) has attracted significant attention because of its superior properties as well as its potential as an ideal dielectric layer for graphene-based devices. The h-BN films obtained via chemical vapour deposition in earlier reports are always polycrystalline with small grains because of high nucleation density on substrates. Here we report the successful synthesis of large single-crystal h-BN grains on rational designed Cu-Ni alloy foils. It is found that the nucleation density can be greatly reduced to 60 per mm(2) by optimizing Ni ratio in substrates. The strategy enables the growth of single-crystal h-BN grains up to 7,500 mu m(2), approximately two orders larger than that in previous reports. This work not only provides valuable information for understanding h-BN nucleation and growth mechanisms, but also gives an effective alternative to exfoliated h-BN as a high-quality dielectric layer for large-scale nanoelectronic applications.
通讯机构：
[He, Yuehui] Cent S Univ, State Key Lab Powder Met, Sch Phys Sci & Technol, Changsha 410083, Peoples R China.
摘要：
Copper nanoparticles encapsulated by multi-layer graphene have been produced in large quantity (in grams) by metal-organic chemical vapor deposition at 600 degrees C with copper(II) acetylacetonate powders as precursor. The obtained graphene/copper shell/core nanoparticles were found to be formed by a novel coalescence mechanism that is quite different from the well-known dissolution-precipitation mechanism for some other graphene/metal (such as nickel, iron or cobalt) shell/core nanoparticles. Differential scanning calorimetry and thermogravimetric analyses showed that the copper nanoparticles encapsulated by multi-layer graphene with a thickness of 1-2 nm were thermally stable up to 165 degrees C in air atmosphere. Moreover, high-resolution transmission electron microscopy showed that the single-crystal copper nanoparticles, after exposure to air for 60 days, did not exhibit any sign of oxidation. (C) 2012 Elsevier Ltd. All rights reserved.
期刊：
CHEMICAL REVIEWS,2015年115(11):5570-5603 ISSN：0009-2665
通讯作者：
Yang, Junliang
作者机构：
[Yang, Junliang] Cent S Univ, Sch Phys & Elect, Inst Super Microstruct & Ultrafast Proc Adv Mat, Changsha 410083, Hunan, Peoples R China.;[Yang, Junliang] Cent S Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Hunan, Peoples R China.;[Yan, Donghang] Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Jilin, Peoples R China.;[Jones, Tim S.] Univ Warwick, Dept Chem, Coventry CV4 7AL, W Midlands, England.
通讯机构：
[Yang, Junliang] Cent S Univ, Sch Phys & Elect, Inst Super Microstruct & Ultrafast Proc Adv Mat, Changsha 410083, Hunan, Peoples R China.
摘要：
Molecular template growth (MTG) is a newly developed method for fabricating high-quality organic semiconductor thin films with controllable morphologies, molecular orientations, electronic structures, and interface properties to produce high-performance organic electronic and optoelectronic devices. There are several MTG methods with different molecular template materials and growth behaviors, including multiphenyl- and multithiophene-based MTG, and perylene-derivative MTG. Extensive research works have also revealed that Individualized methods for fabricating high-quality organic semiconductor thin films with controllable thin-film properties can be developed on the basis of specific understandings of the growth behaviors of organic semiconductor molecules and the desired device structures.
关键词：
graphene;antidot lattices;bandgap;electronic structure;first-principles calculations;tight-binding model
摘要：
The electronic structure of graphene antidot lattices (GALs) with zigzag hole edges was studied with first-principles calculations. It was revealed that half of the possible GAL patterns were unintentionally missed in the usual construction models used in earlier studies. With the complete models, the bandgap of the GALs was sensitive to the width W of the wall between the neighboring holes. A nonzero bandgap was opened in hexagonal GALs with even W, while the bandgap remained closed in those with odd W. Similar alternating gap opening/closing with W was also demonstrated in rhombohedral GALs. Moreover, analytical solutions of single-walled GALs were derived based on a tight-binding model to determine the location of the Dirac points and the energy dispersion, which confirmed the unique effect in GALs.
作者机构：
[Bao, Qiaoliang; Lin, Shenghuang; Mu, Haoran; Li, Pengfei; Chen, Yao] Soochow Univ, Collaborat Innovat Ctr Suzhou Nano Sci & Technol, Jiangsu Key Lab Carbon Based Funct Mat & Devices, Inst Funct Nano & Soft Mat FUNSOM, Suzhou 215123, Peoples R China.;[Lin, Shenghuang; Lau, Shu Ping] Hong Kong Polytech Univ, Dept Appl Phys, Hong Kong 999077, Hong Kong, Peoples R China.;[Wang, Zhongchi; Pan, Chunxu] Wuhan Univ, Sch Phys & Technol, Wuhan 430072, Peoples R China.;[Xiao, Si] Cent S Univ, Hunan Key Lab Super Microstruct & Ultrafast Proc, Sch Phys & Elect, Inst Super Microstruct & Ultrafast Proc Adv Mat, Changsha 410083, Peoples R China.;[Fan, Dianyuan; Zhang, Han] Shenzhen Univ, Minist Educ & Guangdong Prov, SZU NUS Collaborat Innovat Ctr Optoelect Sci & Te, Shenzhen 518060, Peoples R China.
通讯机构：
[Bao, Qiaoliang] Soochow Univ, Collaborat Innovat Ctr Suzhou Nano Sci & Technol, Jiangsu Key Lab Carbon Based Funct Mat & Devices, Inst Funct Nano & Soft Mat FUNSOM, Suzhou 215123, Peoples R China.
关键词：
black phosphorus;electrospinning;polymer composites;pulsed lasers;saturable absorbers
摘要：
Black phosphorus (BP) is a very promising material for telecommunication due to its direct bandgap and strong resonant absorption in near‐infrared wavelength range. However, ultrafast nonlinear photonic applications relying on the ultrafast photocarrier dynamics as well as optical nonlinearity in black phosphorus remain unexplored. In this work, nonlinear optical properties of solution exfoliated BP are investigated and the usage of BP as a new saturable absorber for high energy pulse generation in fiber laser is demonstrated. In order to avoid the oxidization and degradation, BP is encapsulated by polymer matrix which is optically transparent in the spectrum range of interest to form a composite. Two fabrication approaches are demonstrated to produce BP‐polymer composite films which are further incorporated into fiber laser cavity as nonlinear media. BP shows very fast carrier dynamics and BP‐polymer composite has a modulation depth of 10.6%. A highly stable Q‐switched pulse generation is achieved and the single pulse energy of 194 nJ is demonstrated. The ease of handling of such black phosphorus‐polymer composite thin films affords new opportunities for wider applications such as optical sensing, signal processing, and light modulation.
摘要：
Sb2Se3 is a promising absorber material for photovoltaic cells because of its optimum band gap, strong optical absorption, simple phase and composition, and earth-abundant and nontoxic constituents. However, this material is rarely explored for photovoltaic application. Here we report Sb2Se3 solar cells fabricated from thermal evaporation. The rationale to choose thermal evaporation for Sb2Se3 film deposition was first discussed, followed by detailed characterization of Sb2Se3 film deposited onto FTO with different substrate temperatures. We then studied the optical absorption, photosensitivity, and band position of Sb2Se3 film, and finally a prototype photovoltaic device FTO/Sb2Se3/CdS/ZnO/ZnO:Al/Au was constructed, achieving an encouraging 2.1% solar conversion efficiency.
关键词：
Fractional-order hyperchaotic system (FOHS);Feedback control;Laplace transform;Synchronization;Lu hyperchaotic system
摘要：
This work investigates chaos synchronization between two different fractional-order hyperchaotic system (FOHS)s. A novel FOHS is also proposed in this paper. The Chen FOHS is controlled to be a new FOHS and the Lu FOHS, respectively. The analytical conditions for the synchronization of these pairs of different FOHSs are derived by utilizing Laplace transform. Furthermore, synchronization between two different FOHSs is achieved by utilizing feedback control method in a quite short period and both remain in chaotic states. Numerical simulations are used to verify the theoretical analysis using different values of the fractional-order parameter.
