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Keun Man Song, Do Hyun Kim, Jong Min Kim, Chu-Young Cho, Jehyuk Choi, Ka Hee Kim, Jinsub Park, Hogyoung Kim
We demonstrated an InGaN/GaN-based, monolithic, white light-emitting diode (LED) without phosphors by using morphology-controlled active layers formed on multi-facet GaN templates containing polar and semipolar surfaces. The nanostructured surface morphology was controlled by changing the growth time, and distinct multiple photoluminescence peaks were observed at 360, 460, and 560 nm; these features were caused by InGaN/GaN-based multiple quantum wells (MQWs) on the nanostructured facets. The origin of each multi-peak was related to the different indium (In) compositions in the different planes of the quantum wells grown on the nanostructured GaN...
April 27, 2017: Nanotechnology
Navneet Dhindsa, Simarjeet Saini
A novel fabrication method using controlled sacrificial etching of the mask is utilized to fabricate tapered vertical GaAs nanowire arrays. Experimental measurements of the absorption characteristics show that the tapered nanowires absorb over a broadband range as compared to cylindrical ones. The broadband characterization is verified by using optical modeling and results from improved coupling of the nanowires due to distinct radial HE modes being excited separately in the taper and the cylindrical part. The absorption is found to be more broadband as compared to conical nanowires studied so far...
April 27, 2017: Nanotechnology
Yujuan He, Ki-Joong Kim, Chih-Hung Alex Chang
Hollow silica nanoparticles (HSNPs) were synthesized using a microreactor-assisted system with a hydrodynamic focusing micromixer (HFM). Due to the fast mixing of each precursor in the system, the PAA thermodynamic-locked (TML) conformations were protected from their random aggregations by the immediately initiated growth of silica shells. When altering the mixing time through varying flow rates and flow rate ratios, the different degrees of the aggregation of PAA TML conformations were observed. The globular and necklace-like TML conformations were successfully captured by modifying the PAA concentration at the optimized mixing condition...
April 26, 2017: Nanotechnology
Sung-Soo Kim, Donghwi Kang, Byeong-Hyeok Sohn
We report the synthesis of arrayed nanorings with tunable physical dimensions from thin films of polystyrene-<i>block</i>-poly(4-vinylpyridine) (PS-P4VP) micelles. For accurate control of the inner and outer diameters of the nanorings, we added imidazolium-based ionic liquids (ILs) into the micellar solution, which were eventually incorporated into the micellar cores. We observed the structural changes of the micellar cores coated on a substrate due to the presence of ILs. The spin-coated micellar cores were treated with an acidic precursor solution and generated toroid nanostructures, of which size depended on the amount of IL loaded into the micelles...
April 26, 2017: Nanotechnology
Hongyan Gao, Junjie Xiang, Yan Cao
We developed a simple and controlled method to synthesize FeCo2O4@MnO2 core-sheath nanoarchitecture (CSN) grown on the Ni foam. Ultrathin FeCo2O4 nanoflakes with an average thickness of 10 nm served as the scaffold to deposit MnO2 nanosheets. The MnO2 nanosheets were able to vertically grow on FeCo2O4 nanoflakes to form a sheath via a hydrothermal reaction. The nanocomposites' thickness can be tailored from 80 nm to 550 nm by changing the reaction times. Electrochemical measurements demonstrated that FeCo2O4@MnO2 CSN with an optimal thickness about 400 nm achieved an areal capacitance of 3...
April 26, 2017: Nanotechnology
Yibai Sun, Wanlin Fu, Yunqian Dai, Yiyang Huang, Jie Zhou, Chengqian Huang, Chongya Yang, Meiyou Huang, Rongwei Ma, Baoping Lin
Graphene sheets, a flexible two-dimensional material with excellent absorptive capacity, have great potential as absorbing materials. However, it has always been suffering from irreversible aggregation and thus lose the abundant active sites and large surface area. In this paper, large-scale graphene oxide (GO) sheets were cut and reduced into tiny reduced graphene oxide (RGO) sheets by a cell-break sonicator, for producing numerous defects which is the center of chemisorption. Furthermore, sodium titanate nanowires functioned as a framework help to disperse tiny RGO sheets uniformly...
April 26, 2017: Nanotechnology
Rifat Kaçar, Selin Mucur, Fikret Yildiz, Salih Dabak, Emine Tekin
The electrode/organic interface is one of the crucial key factor to attain superior device performance in organic electronics, and inserting a tailor-made layer can dramatically modify its properties. Using of nano-composite (NC) materials lead to many advantages by combining the materials with the objective of getting desirable combination of properties. In this context, zinc oxide/polyethyleneimine (ZnO:PEI) NC film was incorporated as the interfacial layer into the inverted bottom-emission organic light emitting diodes (IBOLEDs) and fully optimized...
April 25, 2017: Nanotechnology
Luca Passoni, Francesco Fumagalli, Andrea Perego, Sebastiano Bellani, Piero Mazzolini, Fabio di Fonzo
Monolithic dye sensitized solar cell architectures hold great potential for building integrated photovoltaics applications. They indeed benefit from lower weight and manufacturing costs as they avoid the use of a transparent conductive oxide coated glass counter electrode. In this work a transparent monolithic dye-sensitized solar cell comprising hierarchical 1D nanostructures stack is fabricated by physical vapour deposition techniques. The proof of concept device comprises hyperbranched TiO<sub>2 </sub> nanostructures, sensitized by the prototypical N719, as photoanode, a hierarchical nanoporous Al<sub>2 </sub>O<sub>3 </sub> spacer and a microporous ITO top electrode...
April 25, 2017: Nanotechnology
Dongchan Lee, Donghyuk Kim, Yonghee Lee, Duk Young Jeon
Graphene has attracted great attention owing to its superb properties as an anode of organic or polymer light-emitting diodes (OLEDs or PLEDs). However, there are still barriers for graphene to replace existing indium tin oxide (ITO) due to relatively high sheet resistance and workfunction mismatch. In this study, PLEDs using molybdenum oxide (MoO<sub>x</sub>) nanoparticle-doped graphene are demonstrated on a plastic substrate to have a low sheet resistance and a high workfunction. Also, this work shows how the doping amount influence on electronic properties of graphene anode and the PLED performance...
April 24, 2017: Nanotechnology
Weiwei Zhou, Dong Wang, Limin Zhao, Chunyan Ding, Xingtao Jia, Yu Du, Guangwu Wen, Huatao Wang
We rationally designed a facile two-step approach to synthesize ZnMn2O4@G composite anode material for lithium-ion batteries (LIBs), involving a template-free fabrication of ZnMn2O4 nanorings and subsequent coating of graphene sheets. Notably, it is the first time that ring-like ZnMn2O4 nanostructure is reported. Moreover, our system has been demonstrated to be quite powerful in producing ZnMn2O4 nanorings regardless of the types of Zn and Mn-containging metal salts reactants. The well-known inside-out Ostwald ripening process is tentatively proposed to clarify the formation mechanism of the hollow nanorings...
April 24, 2017: Nanotechnology
Hong Li, Xiutong Wang, Qinyi Wei, Xueqing Liu, Zhouhai Qian, Baorong Hou
Ag and graphene co-sensitized TiO2 composites were successfully fabricated and used as photoanodes for photogenerated cathodic protection of 304 stainless steel (304SS) under visible light. Graphene films was firstly deposited onto the TiO2 nanotube (NT) films via cyclic voltammetric electrodeposition. Ag/graphene/TiO2 films were then fabricated via dipping and photoreduction method. The morphology, composition and optical response of the Ag/graphene/TiO2 NT composites were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, respectively...
April 21, 2017: Nanotechnology
Lang Liu, Han-Yu Li, Dong Ye, Yao Yu, Lin Liu, Yue Wu
Silver nanowire (AgNW) thin film is a promising candidate to replace traditional indium tin oxide in optoelectronics applications. To date however, the widespread application of AgNW thin film is limited by the weak point contacts between individual AgNWs and the lack of facile patterning techniques. Here, we demonstrate a novel and facile method to not only nanoweld AgNW junctions but also pattern AgNW thin films via mask-free cold plasma-jet scanning in ambient conditions. After the plasma-jet nanowelding treatment, the morphology of AgNWs change substantially and the junctions are welded together...
April 19, 2017: Nanotechnology
Sarkis Dagesyan, Vladislav Shorokhov, Denis Presnov, Eugeniy Soldatov, Artem S Trifonov, Vladimir Krupenin
Here we present the original CMOS compatible fabrication method of the single-electron transistor structure with an extremely small islands, formed by solitary phosphorus dopants in the silicon nanobridge. Its key feature is the controllable size reduction of the nanobridge in sequential cycles of low energy isotropic reactive ion etching that results in a decreased number of active charge centers (dopants) in nanobridge from hundreds to single ones. Electron transport through the individual phosphorous dopants in the silicon lattice was studied...
April 19, 2017: Nanotechnology
Zengyuan Pang, Qingxin Nie, Pengfei Lv, Jian Yu, Fenglin Huang, Qufu Wei
We report a room temperature ammonia sensor with extra high response values and ideal flexibility, including polyaniline (PANI) coated titanium dioxide- silicon dioxide (TiO2-SiO2) or copper oxide- titanium dioxide- silicon dioxide (CuO-TiO2-SiO2) composite nanofibers. Such flexible inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers were prepared by electrospinning, followed by calcination. Then in situ polymerization of aniline monomers was operated with inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers as templates...
April 19, 2017: Nanotechnology
Juneseok You, Yeongjin Song, Chanho Park, Kuewhan Jang, Sungsoo Na
Silver ions have been used to sterilize many products, however, it has recently been demonstrated that silver ions can be toxic. This toxicity has been researched over many years with the lethal concentration at 10 μM. Silver ions can accumulate through the food chain, causing serious health problems in species. Hence, there is a need for a commercially available silver ion sensor, with high detection sensitivity. In this work, we develop an ultra-sensitive silver ion sensor platform, using cytosine-based DNA and gold nanoparticle as the mass amplifier...
April 13, 2017: Nanotechnology
Pranab Biswas, Seong Rae Cho, Jong-Woo Kim, Sung-Doo Baek, Jae-Min Myoung
In this study, plasmonic silver (Ag) nanoparticles (NPs)-anchored ZnO nanorods (NRs) and nanotubes (NTs)-based UV photodetectors are demonstrated. Here, Ag NPs are synthesized and anchored by using a room-temperature photochemical method by exposing the precursor solution in UV radiation. In order to achieve stronger surface plasmon resonance (SPR) and minimum agglomeration, the photochemical method is optimized with precursor concentration of 5 mmol, UV intensity of 0.4 mW• cm-2, and exposure time of 30 min...
April 12, 2017: Nanotechnology
Yu Wang, Xue Bai, Tongyu Wang, Long Yan, Tieqiang Zhang, Yu Zhang, William Yu
Recently, near-infrared light-emitting diodes (NIR LEDs) based on PbSe quantum dots (QDs) have attracted considerable attention due to their facilely tunable emission wavelength, as well as high quantum yield. However, the low external quantum efficiency (EQE) of these LEDs has restricted their actual applications because of the non-radiative recombination caused by the aggregation in the solid-state QD films. Therefore, we proposed in this work to employ the liquid-type structure in NIR LEDs base on PbSe QDs, which exhibited the main advantages relying on the fact that the liquid structure could prevent the active layer from self-aggregation and improve the device stability...
April 12, 2017: Nanotechnology
Arezoo Dianat, Zhongquan Liao, Martin Gall, Tao Zhang, Rafael Gutierrez, Ehrenfried Zschech, Gianaurelio Cuniberti
In this work, we show the doping of graphene most likely from heteroatoms induced by the substrate using Raman spectrum, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX) and ab initio molecular dynamics simulations. The doping of graphene on a highly boron-doped silicon substrate was achieved by an annealing at 400 K for about 3 hours in an oven with air flow. With the same annealing, only the Raman features similar to that from the pristine graphene were observed in the freestanding graphene and the graphene on a typical Si/SiO2 wafer...
April 12, 2017: Nanotechnology
Xu Zhang, Wentao Zhang, Lizhi Liu, Mei Yang, Lunjie Huang, Kai Chen, Rong Wang, Baowei Yang, Daohong Zhang, Jianlong Wang
The emergence of antibiotic resistance has resulted in an increasing difficulty treating clinical infections associated with biofilms formation, one of the key processes contributed to enhance antibiotic resistance in return. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance was opened up. Based on multiple properties especially antibacterial potential of MoS<sub>2</sub> nanosheets that have aroused wide attention, herein, a novel antimicrobial agent to combat resistant gram-positive <i>Staphylococcus aureus (S...
April 11, 2017: Nanotechnology
Jiangtao Lv, Eng Huat Khoo, Eunice Sok Ping Leong, Litao Hu, Xiaoxiao Jiang, Yong Li, Dan Luo, Guangyuan Si, Yan Jun Liu
We report maskless fabrication of high-aspect-ratio slanted annular aperture arrays (SAAAs) in gold films using focused ion beam lithography. By tilting the substrate, SAAAs with the desired tilting angle can be fabricated. Our experimental results demonstrate the accurate control over aperture size, obliqueness, and reproducibility. We also show that the resulted plasmonic resonances of SAAAs can be effectively tuned via obliqueness control. This versatile approach may enable fabrication of more complicated plasmonic nanostructures...
April 11, 2017: Nanotechnology
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