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41.
We have studied systematically room-temperature photoluminescence (PL) properties of many nanostructured ZnO samples grown by chemical vapour deposition (CVD). Their PL spectra consist of two emissions peaked in the ultraviolet (UV) and green regions. The relative intensity of these emissions depends on the excitation energy density, size and morphology of ZnO nanostructures. Based on the excitation-density dependence of the integrated intensity ratio of UV-to-green emission, we could classify PL spectra of ZnO nanostructures into three groups characteristic of size and morphology. Our study also reveals that with increasing excitation density, the UV-peak position shifts slightly towards longer wavelengths while the green emission around 514-520 nm is almost unchanged. This green-luminescence emission is dominant when the nanostructure sizes range from 20 to 200 nm, which is related to a large surface-to-volume ratio. 相似文献
42.
Brightening single-photon emitters by combining an ultrathin metallic antenna and a silicon quasi-BIC antenna 下载免费PDF全文
Bright single-photon emitters(SPEs)are fundamental components in many quantum applications.However,it is difficult to simultaneously get large Purcell enhancements and quantum yields in metallic nanostructures because of the huge losses in the metallic nanostructures.Herein,we propose to combine an ultrathin metallic bowtie antenna with a silicon antenna above a metallic substrate to simultaneously get large Purcell enhancements,quantum yields,and collection efficiencies.As a result,the brightness of SPEs in the hybrid nanostructure is greatly increased.Due to the deep subwavelength field confinement(mode size<10 nm)of surface plasmons in the ultrathin metallic film(thickness<4 nm),the Purcell enhancement of the metallic bowtie antenna improves by more than 25 times when the metal thickness decreases from 20 nm to 2 nm.In the hybrid nanostructures by combining an ultrathin metallic bowtie antenna with a silicon antenna,the Purcell enhancement(Fp≈2.6×106)in the hybrid nanostructures is 63 times greater than those(≤4.1×104)in the previous metallic and hybrid nanostructures.Because of the reduced ratio of electromagnetic fields in the ultrathin metallic bowtie antenna when the high-index silicon antenna is under the quasi-BIC state,a high quantum yield(QY≈0.70)is obtained.Moreover,the good radiation directivity of the quasi-BIC(bound state in the continuum)mode of the silicon antenna and the reflection of the metallic substrate result in a high collection efficiency(CE≈0.71).Consequently,the overall enhancement factor of brightness of a SPE in the hybrid nanostructure is EF?≈Fp×QY×CE≈1.3×106,which is 5.6×102 times greater than those(EF?≤2.2×103)in the previous metallic and hybrid nanostructures. 相似文献
43.
Hongkang Wang Yu Wang Stephen V. Kershaw Tak Fu Hung Jun Xu Andrey L. Rogach 《Particle & Particle Systems Characterization》2013,30(4):332-337
Fluorinated Eu‐doped SnO2 nanostructures with tunable morphology (shuttle‐like and ring‐like) are prepared by a hydrothermal method, using NaF as the morphology controlling agent. X‐ray diffraction, field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, X‐ray photoelectron spectroscopy, and energy dispersive spectroscopy are used to characterize their phase, shape, lattice structure, composition, and element distribution. The data suggest that Eu3+ ions are uniformly embedded into SnO2 nanocrystallites either through substitution of Sn4+ ions or through formation of Eu‐F bonds, allowing for high‐level Eu3+ doping. Photoluminescence features such as transition intensity ratios and Stark splitting indicate diverse localization of Eu3+ ions in the SnO2 nanoparticles, either in the crystalline lattice or in the grain boundaries. Due to formation of Eu‐F and Sn‐F bonds, the fluorinated surface of SnO2 nanocrystallites efficiently inhibits the hydroxyl quenching effect, which accounts for their improved photoluminescence intensity. 相似文献
44.
Ye Jiang Honglie Shen Tian Pu Chaofan Zheng Quntao Tang Wangyang Yang Jing Wu Chunbao Rui Yufang Li 《固体物理学:研究快报》2016,10(12):870-873
Acid texture is difficult for diamond wire sawn (DWS) multicrystalline silicon (mc‐Si) wafer owing to the inhomogeneous distribution of damage layer on the surface. In this article, metal‐assisted chemical etching (MACE) has been selected for introducing a porous seeding layer to induce acid texturing etching. SEM results show that the oval pit structures coverage get obvious improvement even on the smooth areas. Owing to the further improved light absorption ability by second MACE and nanostructure rebuilding (NSR) process, nanostructured DWS mc‐Si solar cell has exhibited a conversion efficiency of 17.96%, which is 0.45% higher than that of DWS wafer with simple acid texture process. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
45.
Hao Wu Lu Zhang Jinfan Yang Ruonan Bo Hongxu Du Kai Lin Dalin Zhang Mythili Ramachandran Yingbin Shen Yangxi Xu Xiangdong Xue Zhao Ma Aaron Raymond Lindstrom Randy Carney Tzu‐Yin Lin Yuanpei Li 《Advanced functional materials》2020,30(15)
Real‐time tracking of the dynamics change of self‐assembled nanostructures in physiological environments is crucial to improving their delivery efficiency and therapeutic effects. However, such tracking is impeded by the complex biological microenvironment leading to inhomogeneous distribution. A rotatable fluorescent ratio strategy is introduced that integrates aggregation‐induced emission (AIE) and aggregation‐caused quenching (ACQ) into one nanostructured system, termed AIE and ACQ fluorescence ratio (AAR). Following this strategy, an advanced probe, PEG5k‐TPE4‐ICGD4 (PTI), is developed to track the dynamics change. The extremely sharp fluorescent changes (up to 4008‐fold) in AAR allowed for the clear distinguishing and localization of the intact state and diverse dissociated states. The spatiotemporal distribution and structural dynamics of the PTI micelles can be tracked, quantitatively analyzed in living cells and animal tissue by the real‐time ratio map, and be used to monitor other responsive nanoplatforms. With this method, the dynamics of nanoparticle in different organelles are able to be investigated and validated by transmission electron microscopy. This novel strategy is generally applicable to many self‐assembled nanostructures for understanding delivery mechanism in living systems, ultimately to enhance their performance in biomedical applications. 相似文献
46.
Qiong Zeng Jinsheng Cheng Longhua Tang Xiaofei Liu Yanzhe Liu Jinghong Li Jianhui Jiang 《Advanced functional materials》2010,20(19):3366-3372
The self‐assembly of sodium dodecyl benzene sulphonate (SDBS) functionalized graphene sheets (GSs) and horseradish peroxidase (HRP) by electrostatic attraction into novel hierarchical nanostructures in aqueous solution is reported. Data from scanning electron microscopy, high‐resolution transmission electron microscopy, and X‐ray diffraction demonstrate that the HRP–GSs bionanocomposites feature ordered hierarchical nanostructures with well‐dispersed HRP intercalated between the GSs. UV‐vis and infrared spectra indicate the native structure of HRP is maintained after the assembly, implying good biocompatibility of SDBS‐functionalized GSs. Furthermore, the HRP–GSs composites are utilized for the fabrication of enzyme electrodes (HRP–GSs electrodes). Electrochemical measurements reveal that the resulting HRP–GSs electrodes display high electrocatalytic activity to H2O2 with high sensitivity, wide linear range, low detection limit, and fast amperometric response. These desirable electrochemical performances are attributed to excellent biocompatibility and superb electron transport efficiency of GSs as well as high HRP loading and synergistic catalytic effect of the HRP–GSs bionanocomposites toward H2O2. As graphene can be readily non‐covalently functionalized by “designer” aromatic molecules with different electrostatic properties, the proposed self‐assembly strategy affords a facile and effective platform for the assembly of various biomolecules into hierarchically ordered bionanocomposites in biosensing and biocatalytic applications. 相似文献
47.
Mengjiao Xu Minxuan Wang Hao Xu Prof. Dr. Huaiguo Xue Prof. Dr. Huan Pang 《化学:亚洲杂志》2016,11(21):2967-2995
Electrospinning, as a novel nontextile filament technology, is an important method to prepare continuous nanofibers and has shown its remarkable advantages, such as a broadly applicable material system, controllable fiber size and structure, and simple process. Electrospun nanofiber membranes prepared by electrospinning have shown promising applications in many fields, such as supercapacitors, lithium‐ion batteries, and sodium‐ion batteries, owing to their large specific surface area and adjustable network pore structure. The principle of electrospinning and key points relevant to its usage in the preparation of high‐performance electrochemical energy storage materials are reviewed herein based on recent publications, particularly focusing on research progress of relative materials. Also, this review describes a distinctive conclusion and perspective on the future challenges and opportunities in electrospun nanomaterials. 相似文献
48.
Zifeng Wang Zijie Tang Qi Xue Yan Huang Yang Huang Minshen Zhu Zengxia Pei Hongfei Li Hongbo Jiang Chenxi Fu Chunyi Zhi 《Chemical record (New York, N.Y.)》2016,16(3):1204-1215
Nanomaterials with layered structures, with their intriguing properties, are of great research interest nowadays. As one of the primary two‐dimensional nanomaterials, the hexagonal boron nitride nanosheet (BNNS, also called white graphene), which is an analogue of graphene, possesses various attractive properties, such as high intrinsic thermal conductivity, excellent chemical and thermal stability, and electrical insulation properties. After being discovered, it has been one of the most intensively studied two‐dimensional non‐carbon nanomaterials and has been applied in a wide range of applications. To support the exploration of applications of BNNSs, exfoliation, as one of the most promising approaches to realize large‐scale production of BNNSs, has been intensively investigated. In this review, methods to yield BNNSs by exfoliation will be summarized and compared with other potential fabrication methods of BNNSs. In addition, the future prospects of the exfoliation of h‐BN will also be discussed. 相似文献
49.
Our sense of touch enables us to recognize texture and shape and to grasp objects. The challenge in making an electronic skin which can emulate touch for applications such as a humanoid robot or minimally invasive and remote surgery is both in mimicking the (passive) mechanical properties of the dermis and the characteristics of the sensing mechanism, especially the intrinsic digital nature of neurons. Significant progress has been made towards developing an electronic skin by using a variety of materials and physical concepts, but the challenge of emulating the sense of touch remains. Recently, a nanodevice was developed that has achieved the resolution to decipher touch on a par with the human finger; this resolution is over an order of magnitude improvement on previous devices with a sensing area larger than 1 cm(2). With its robust mechanical properties, this new system represents an important step towards the realization of artificial touch. 相似文献
50.