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ABSTRACT: Energy storage on paper: paper-based, all-solid-state, and flexible supercapacitors were fabricated, which can be charged by a piezoelectric generator or solar cells and then discharged to power a strain sensor or a blue-light-emitting diode, demonstrating its efficient energy management in self-powered nanosystems.
Angewandte Chemie International Edition 04/2012; 51(20):4934-8. · 13.45 Impact Factor
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Xihong Lu,
Teng Zhai,
Xianghui Zhang,
Yongqi Shen, Longyan Yuan,
Bin Hu,
Li Gong,
Jian Chen,
Yihua Gao,
Jun Zhou,
Yexiang Tong,
Zhong Lin Wang
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ABSTRACT: WO3–x@Au@MnO2 core–shell nanowires (NWs) are synthesized on a flexible carbon fabric and show outstanding electrochemical performance in supercapacitors such as high specific capacitance, good cyclic stability, high energy density, and high power density. These results suggest that the WO3–x@Au@MnO2 NWs have promising potential for use in high-performance flexible supercapacitors.
Advanced Materials 02/2012; 24(7):938-44. · 13.88 Impact Factor
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ABSTRACT: We report a systematic study about the anisotropic third-order optical nonlinearity of a single ZnO micro/nanowire by using the Z-scan method with a femtosecond laser. The two-photon absorption coefficient and nonlinear refraction index, which are measured as a function of polarization angle and sample orientation angle, exhibit oscillation curves with a period of π/2, indicating a highly polarized optical nonlinearity of the ZnO micro/nanowire. Further studies show that the polarized optical nonlinearity of the ZnO micro/nanowire is highly size-dependent. The results indicate that ZnO nanowire has great potential in applications of nanolasers, all-optical switching and polarization-sensitive photodetectors.
Nano Letters 01/2012; 12(2):833-8. · 13.20 Impact Factor
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Longyan Yuan,
Xi-Hong Lu,
Xu Xiao,
Teng Zhai,
Junjie Dai,
Fengchao Zhang,
Bin Hu,
Xue Wang,
Li Gong,
Jian Chen,
Chenguo Hu,
Yexiang Tong,
Jun Zhou,
Zhong Lin Wang
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ABSTRACT: A highly flexible solid-state supercapacitor was fabricated through a simple flame synthesis method and electrochemical deposition process based on a carbon nanoparticles/MnO(2) nanorods hybrid structure using polyvinyl alcohol/H(3)PO(4) electrolyte. Carbon fabric is used as a current collector and electrode (mechanical support), leading to a simplified, highly flexible, and lightweight architecture. The device exhibited good electrochemical performance with an energy density of 4.8 Wh/kg at a power density of 14 kW/kg, and a demonstration of a practical device is also presented, highlighting the path for its enormous potential in energy management.
ACS Nano 12/2011; 6(1):656-61. · 10.77 Impact Factor
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ABSTRACT: A type of strain sensor with high tolerable strain based on a ZnO nanowires/polystyrene nanofibers hybrid structure on a polydimethylsiloxane film is reported. The novel strain sensor can measure and withstand high strain and demonstrates good performance on rapid human-motion measurements. In addition, the device could be driven by solar cells. The results indicate that the device has potential applications as an outdoor sensor system.
Advanced Materials 12/2011; 23(45):5440-4. · 13.88 Impact Factor
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Xianghui Zhang,
Xihong Lu,
Yongqi Shen,
Jingbin Han, Longyan Yuan,
Li Gong,
Zhi Xu,
Xuedong Bai,
Min Wei,
Yexiang Tong,
Yihua Gao,
Jian Chen,
Jun Zhou,
Zhong Lin Wang
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ABSTRACT: Three-dimensional (3D) WO(3) nanostructures were grown on carbon paper by a catalyst-free high temperature reactive vapor deposition process, which exhibit a good photoelectrochemical property and visible light driven photocatalytic performance.
Chemical Communications 05/2011; 47(20):5804-6. · 6.17 Impact Factor
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Longyan Yuan,
Yuting Tao,
Jian Chen,
Junjie Dai,
Ting Song,
Mingyue Ruan,
Zongwei Ma,
Li Gong,
Kang Liu,
Xianghui Zhang,
Xuejiao Hu,
Jun Zhou,
Zhong Lin Wang
Advanced Functional Materials 04/2011; 21(11):2150 - 2154. · 10.18 Impact Factor
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Longyan Yuan,
Junjie Dai,
Xiaohong Fan,
Ting Song,
Yu Ting Tao,
Kai Wang,
Zhi Xu,
Jun Zhang,
Xuedong Bai,
Peixiang Lu,
Jian Chen,
Jun Zhou,
Zhong Lin Wang
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ABSTRACT: Highly flexible, robust, and sensitive infrared nanosensors were fabricated based on carbon nanoparticles that were synthesized through a simple and low-cost flame method. The infrared nanosensor devices showed sharp infrared photoresponse with a response time of ∼68 ms and a maximum photocurrent change of ∼52.9%. The devices showed a superhydrophobic property with a contact angle larger than 150° and a sliding angle of ∼4°. The mechanism for the enhanced infrared photoresponse from carbon nanoparticles is discussed.
ACS Nano 04/2011; 5(5):4007-13. · 10.77 Impact Factor
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ABSTRACT: Novel strain sensor based on ZnO bridging nanorods has been fabricated on Kapton substrate by a single-step hydrothermal reaction, and fully packaged by a polydimethylsioxane layer. Via introducing a metastable contact that can be controlled by strain, flexible strain sensors with high sensitivity and a strain driving transistor with an ultrahigh 107 scale “on”−“off” ratio have been demonstrated. However, high performance devices only come from the samples fabricated with lower nutrient solution concentration and are only sensitive to tensile strain. We found out that the response behavior strongly depends on the device structure. The I−V characteristic is highly sensitive to strain due to the change in Schottky barrier height, as well as the change of contact area between ZnO bridging nanorods induced by the metastable morphology under strain.
12/2010;
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ABSTRACT: Lateral zinc oxide (ZnO) nanorod metal-semiconductor-metal ultraviolet detectors with different metal contact were fabricated on glass substrate by a single-step hydrothermal reaction. With the combined effect from a ZnO seed layer and an inactive layer for nanorod growth, ZnO nanorods could grow laterally and aligned between the interdigitated electrodes. When the growth process is terminated, the integration of ZnO nanorods into a function device can be achieved in the meantime. The structure can be modeled as being composed of two same Schottky barriers connected back to back, in series with a resistance of R. The devices are visible-blind and have great response even in mid ultraviolet region. The photodetectors with Ni electrode show better performance both in the aspect of photocurrent and response time, owing to the larger Schottky barrier at the Ni/ZnO interface. By surface coating with polymethyl methacrylate, the response has been further improved. Our approach provides a simple and effective way to fabricate high performance ultraviolet detectors.
ACS Applied Materials & Interfaces 06/2010; · 4.53 Impact Factor
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ABSTRACT: Novel lateral field emission devices composed of ZnO nanorods have been fabricated by a single-step hydrothermal approach on glass substrate. With the combined effect from a ZnO seed layer and a passivation layer for nanorod growth, ZnO nanorods could grow laterally and aligned between two electrodes. In this way, the conventional “pick and place” method and pattern grown on single crystal of nanorod integration are avoided. All the Fowler−Nordheim (FN) curves are straight lines and in excellent agreement with FN theory, which indicates that the electron emission of the as-grown samples is a tunneling and cold electron emission process. Measurement results also show that the samples with larger separation distance exhibit better field emission characteristics. By calculating the electrostatic field distribution, it was found that the electric field near the surface of the emitter is strongly dependent on the vacuum separation distance.
04/2010;
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ABSTRACT: High-κ HfOxNy and HfO2 films are applied to amorphous InGaZnO (a-IGZO) devices as gate dielectric using radio-frequency reactive sputtering. The electrical characteristics and reliability of a-IGZO metal–insulator–semiconductor (MIS) capacitors and thin-film transistors (TFTs) are then investigated. Experimental results indicate that the nitrogen incorporation into HfO2 can effectively improve the interface quality and enhance the reliability of the devices. Electrical properties with an interface-state density of 5.2 × 1011 eV−1 cm−2, capacitance equivalent thickness of 1.65 nm, gate leakage current density of 3.4 × 10−5 A cm−2 at Vfb +1 V, equivalent permittivity of 23.6 and hysteresis voltage of 110 mV are obtained for an Al/HfOxNy/a-IGZO MIS capacitor. Superior performance of HfOxNy/a-IGZO TFTs has also been achieved with a low threshold voltage of 0.33 V, a high saturation mobility of 12.1 cm2 V−1 s−1 and a large on–off current ratio up to 7 × 107 (W/L = 500/20 µm) at 3 V.
Semiconductor Science and Technology 04/2010; 25(5):055006. · 1.72 Impact Factor
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Microelectronics Reliability. 01/2010; 50:954-958.
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ABSTRACT: The authors report on the field emission from controlled selective grown zinc oxide (ZnO) nanorod arrays by hydrothermal reaction. With the combined effect from a ZnO seed layer and a passivation layer for nanorod growth, ZnO nanorods could only grow on the edge of a 4 μ m diameter circle. The ZnO nanorods hollow arrays present excellent electron emission characteristics duo to its typical morphology which can significantly diminish the screen effect. By calculating the electrostatic field distribution, it was found that the electrostatic field of the ZnO nanorods hollow arrays is significantly higher than that of the solid arrays.
Applied Physics Letters 11/2009; · 3.84 Impact Factor
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ABSTRACT: A ZnO-based metal-insulator (HfO<sub>2</sub>) -semiconductor diode was synthesized on a commercially available n<sup>+</sup>-GaN/sapphire substrate using a radio-frequency magnetron sputtering system. Electroluminescence measurements revealed that the diode exhibited fairly pure ultraviolet (UV) emission peaking at ~ 370 nm with a line width of less than 8 nm. By choosing a proper thickness of the insulator HfO<sub>2</sub> layer, the threshold voltage of the emission could be reduced to 2 V, demonstrating that this ZnO-based fairly pure UV light-emitting diode can be driven by two ordinary dry batteries. The reason for low threshold voltage is proposed in terms of the n<sup>+</sup>-GaN/sapphire substrate and the high- k insulator HfO<sub>2</sub> layer.
IEEE Electron Device Letters 11/2009; · 2.85 Impact Factor
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ABSTRACT: Three types of models, with various emitter shapes in planar electrodes, have been employed to investigate field electron emission characteristics by finite element method. With the model of “hemisphere on a post”, two definitions of field enhancement and field amplification factors and their relation have been discussed systemically at different anode locations. The field distribution in the gap, between emitter apex and anode, is quantified by a field saturation factor. Simulation indicates that field distribution is an important aspect for explaining the nonlinear variation of field amplification factor at different anode locations. Furthermore, the field saturation factor can reflect the saturation degree of field amplification factor. The findings can be used not only in the model of “hemisphere on a post” but also approximately in the models of “two-stage hemisphere on a post” and “hemi-ellipsoid on plane”. Therefore, the fact can be approximately applied to every protruding shape of emitter that is supposed. Comparisons with previously reported experimental and theoretical results are also given.
Diamond and Related Materials 11/2009; 18(11):1381-1386. · 1.91 Impact Factor
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ABSTRACT: Highly transparent and amorphous InGaZnO thin films with high mobility were deposited on fused silica by pulsed laser deposition. The films remained amorphous after annealing at 700 °C and had bandgaps in the range 3.50–3.62 eV. The film deposited at 5 Pa and room temperature exhibits a Hall mobility of 54 cm2 V−1 s−1. An α-InGaZnO thin film transistor with high-k Ba0.6Sr0.4TiO3 as a dielectric layer and operating in enhanced mode with a saturation mobility of 5.8 cm2 V−1 s−1 and on/off ratio of 2 × 105 is demonstrated.
Journal of Physics D Applied Physics 10/2009; 42(21):215301. · 2.54 Impact Factor
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ABSTRACT: The electrochromic (EC) property of WO(3) nanoparticles grown on vertically self-aligned ZnO nanorods (ZNRs) is reported. An electrochromic character display based on WO(3) nanoparticle-modified ZnO nanorod arrays on a flexible substrate has been fabricated and demonstrated. The ZNRs were first synthesized on ZnO-seed-coated In(2)O(3):Sn (ITO) glass (1 cm(2) cell) and polyethylene terephthalate (PET) (4 cm(2) cell) substrates by a low temperature hydrothermal method, and then amorphous WO(3) nanoparticles were grown directly on the surface of the ZNRs by the pulsed laser deposition (PLD) method. The ZNR-based EC device shows high transparence, good electrochromic stability and fast switching speed (4.2 and 4 s for coloration and bleaching, respectively, for a 1 cm(2) cell). The good performance of the ZNR electrode-based EC display can be attributed to the large surface area, high crystallinity and good electron transport properties of the ZNR arrays. Its high contrast, fast switching, good memory and flexible characteristics indicate it is a promising candidate for flexible electrochromic displays or electronic paper.
Nanotechnology 06/2009; 20(18):185304. · 3.98 Impact Factor
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Applied Physics Letters 04/2009; 94(16):166103-166103-2. · 3.84 Impact Factor
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ABSTRACT: N-ZnO nanorods/n-silicon heterojunction was fabricated by growth of ZnO nanorods on a n-type silicon (111) wafer with a low-temperature aqueous solution method. Capacitance-voltage measurements revealed that after annealing at 900 °C in O2 ambient for 1 h, the heterojunction changed from abrupt N-ZnO nanorods/n-silicon to graded P-ZnO/n-silicon junction. The annealed diode showed good photoresponse in both the ultraviolet and visible regions with responsivity around 0.3 and 0.5 A/W without bias. The photoresponses toward ultraviolet and visible light were enhanced when the diode was under reverse and forward bias, respectively. The results were discussed in terms of phosphorus diffusion process and the band diagrams of the heterojunctions in this work.
Applied Physics Letters 02/2009; 94(6):063512-063512-3. · 3.84 Impact Factor
