Synthesis and Luminescent Properties of Strong Blue Light-Emitting Al[sub 2]O[sub 3]/ZnO Nanocables

Hsiao, Chi-Sheng; Kuo, Wan-Lin; Chen, San‐Yuan; Shen, Ji‐Lin; Lin, Chun-Liang; Cheng, Syh-Yuh

doi:10.1149/1.2890289

Cited by 6 publications

(4 citation statements)

References 17 publications

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“…28 Because the ZnO exhibits notable chemical stability and biological compatibility, it has attracted significant attention for applications in photocatalysis, electronics, optoelectronics, and sensors. [29][30][31][32] So far, many forms of ZnO have been fabricated and evaluated for wetting properties. 14,15,[33][34][35] Previously, Papadopoulou et al 36 investigated the nanostructured ZnO films, and determined that the bias necessary to actuate the EW behavior was negligible.…”

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confidence: 99%

Electrowetting of Superhydrophobic ZnO Inverse Opals

Chen

Lai

et al. 2011

J. Electrochem. Soc.

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ZnO inverse opals are fabricated by electrophoresis of polystyrene (PS) microspheres (720 nm in diameter) on a ITO glass to form a close-packed colloidal crystal, followed by potentiostatic deposition of ZnO in the interstitial voids among the PS microspheres and chemical removal of the PS colloidal template. By adjusting the electrodeposition time, we obtain semi-layered and multilayered ZnO inverse structures with significantly reduced defects and considerable surface uniformity. The semi-layered ZnO inverse opals display a bowl-like morphology with individual cavities isolated from each other. In contrast, the multi-layered ZnO inverse opals exhibit a three-dimensional skeleton with hexagonally-arranged cavities interconnected to each other. After surface coating of perfluorodecyltriethoxysilane, both samples reveal a superhydrophobic nature with contact angle larger than 150. In electrowetting measurements, the contact angles are decreasing with increasing applied voltages. The droplet on the semi-layered ZnO inverse opals demonstrates a notable transition from the Cassie-Baxter state to the Wenzel one. However, the droplet on the multi-layered ZnO inverse opals indicates three distinct regimes; Cassie-Baxter state, mixed Cassie-Baxter/Wenzel state, and Wenzel state. Repelling pressure of the entrapped air in the cavities is estimated to explain the observed contact angle variation upon the applied voltage for both samples. The surface property for a solid material can be deliberately controlled from hydrophilic to hydrophobic in order to affect the wetting behavior of a water droplet that is in contact with the solid surface. So far, external stimuli such as electric field, mechanical force, magnetic field, electrochemical reaction, and photon excitation have been employed to manipulate physical and chemical attributes of the surface.1-5 Among them, the electrical route, known as electrowetting (EW), is recognized for its fast response, reversibility, and compatibility with microdevices.6-8 To date, the implementation of EW for applications such as microfluidics and optoelectronic components have been explored. [9][10][11] In EW, the water droplet on the solid surface reveals a significant morphological alteration from a large contact angle (hydrophobic) to a reduced one (hydrophilic) upon the imposition of voltage across the solid surface and water droplet. This is because the electrical field engenders a capacitive charging on the interface that increases its surface energy considerably. As a result, the water droplet is able to wet the solid surface lowering the overall interfacial energy.For a desirable EW material, a large contact angle at zero voltage and a stronger capacitive effect are always preferred. To achieve these objectives, recent research attention has focused on the design and fabrication of one-dimensional materials such as nanowires and nanorods. [12][13][14][15] In general, the wetting behavior for the water droplet on a nanostructured surface can be categorized in Cassie-Baxter model o...

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confidence: 99%

Electrowetting of Superhydrophobic ZnO Inverse Opals

Chen

Lai

et al. 2011

J. Electrochem. Soc.

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“…During phase transformation, pentahedrally coordinated aluminum was produced, and singly ionized oxygen vacancies at the F + centers were responsible for the blue emission. For a detailed discussion, refer to our previous study [12]. In general, the oxygen affinity in alumina is stronger than that in ZnO.…”

Section: Resultsmentioning

confidence: 93%

“…This suggests that the ZnO nanostructure could, after low-temperature growth and hightemperature annealing treatments, be developed for application in photoluminescent devices. In our previous study, we found that when an alumina film was deposited on ZnO nanorods and then annealed at 600 • C in a nitrogen ambient, the alumina-coated ZnO nanorods displayed a strong bluelight emission (the relative intensity (blue/UV) of the samples is up to 20) [12]. This indicated that ZnO strongly affected the photoluminescent properties of nanosized alumina films, leading to different UV to blue light intensity ratios in the PL spectra.…”

Section: Introductionmentioning

confidence: 97%

Synthesis and optical properties of white-light-emitting alumina/ZnO nanotubes

et al. 2008

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A simple chemical solution process was used to prepare alumina nanoparticle-coated ZnO nanotubes (ANZTs). Transmission electron microscope (TEM) images proved that the alumina nanoparticles were uniformly dispersed on the ZnO nanotubes. After thermal treatment at different temperatures under various atmospheres, photoluminescence (PL) measurements showed that the ANZTs emitted a variety of colors, including blue, green and white light. Gaussian curve fitting of the PL spectra revealed that the competition between the blue, blue-green, green and yellow band emissions and their relative emission intensities were strongly associated with various defects. Blue emission was attributed to large numbers of oxygen defects in alumina, while green and yellow emissions were related to oxygen and zinc defects in ZnO, respectively. Under specific conditions, white light, consisting of blue, blue-green, green and yellow band emissions, was obtained. Further TEM analysis indicated that the defect structure of ANZTs could be manipulated by the interface interaction between alumina and the ZnO nanotubes.

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“…1 With impressive chemical stability and biological compatibility, ZnO has attracted considerable attention in recent years for possible applications in photocatalysis, electronics, photovoltaics, optoelectronics, wetting, chemical and biomolecular sensors, and so on. [2][3][4][5][6][7] To further improve its functionality and activity, ZnO is often doped with selective elements with the objective to introduce impurities for modification in both lattice and electronic configurations. 8,9 An alternative route to achieve the same purpose is to fabricate the ZnO in unique forms.…”

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confidence: 99%

Facile Electrochemical Fabrication of Large-Area ZnO Inverse Opals with Reduced Defects

Liao

Huang

et al. 2011

J. Electrochem. Soc.

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We demonstrate a facile fabrication scheme to construct large-area ZnO inverse opals on an indium-tin-oxide substrate with significantly reduced defects and improved stoichiometry. The fabrication steps involve the preparation of colloidal template via vertical electrophoresis of polystyrene (PS) microspheres in 720 nm radius, followed by galvanostatic electrodeposition of ZnO in the interstitial voids among the PS microspheres. Subsequently, the sample undergoes a heat-treatment in air at 500 C for different time to remove the colloidal template, leaving an integral ZnO skeleton with thickness adjusted by the electrodeposition time. Since the colloidal template is deliberately designed with desirable thickness and considerable uniformity, the electroplating of ZnO can be achieved in a reduced ethanol/water ratio that allows faster growth rate and improved ZnO structure. Scanning electron microscope images demonstrate negligible microstructural defects for the ZnO inverse opals. X-ray diffraction reveals a wurtzite hexagonal lattice with (002) preferred orientation. In addition, both X-ray photoelectron spectroscopy and photoluminescence spectra suggest improved crystallinity and stoichiometry with increasing heat-treatment time.

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Synthesis and Luminescent Properties of Strong Blue Light-Emitting Al[sub 2]O[sub 3]/ZnO Nanocables

Cited by 6 publications

References 17 publications

Electrowetting of Superhydrophobic ZnO Inverse Opals

Electrowetting of Superhydrophobic ZnO Inverse Opals

Synthesis and optical properties of white-light-emitting alumina/ZnO nanotubes

Facile Electrochemical Fabrication of Large-Area ZnO Inverse Opals with Reduced Defects

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