Xiao Wei Sun

Bio: Xiao Wei Sun is an academic researcher from Southern University of Science and Technology. The author has contributed to research in topics: Quantum dot & Light-emitting diode. The author has an hindex of 83, co-authored 880 publications receiving 27985 citations. Previous affiliations of Xiao Wei Sun include Hong Kong University of Science and Technology & Northwestern Polytechnical University.

Hydrothermally grown oriented ZnO nanorod arrays for gas sensing applications

Abstract: C-axis vertically aligned ZnO nanorod arrays were synthesized on a ZnO thin film through a simple hydrothermal route. The nanorods have a diameter of 30–100 nm and a length of about several hundred nanometres. The gas sensor fabricated from ZnO nanorod arrays showed a high sensitivity to H2 from room temperature to a maximum sensitivity at 250 °C and a detection limit of 20 ppm. In addition, the ZnO gas sensor also exhibited excellent responses to NH3 and CO exposure. Our results demonstrate that the hydrothermally grown vertically aligned ZnO nanorod arrays are very promising for the fabrication of cost effective and high performance gas sensors.

Blueshift of optical band gap in ZnO thin films grown by metal-organic chemical-vapor deposition

Abstract: The optical band gap of ZnO thin films deposited on fused quartz by metal-organic chemical-vapor deposition was studied. The optical band gap of as-grown ZnO blueshifted from 3.13to4.06eV as the growth temperature decreased from 500to200°C. After annealing, the optical band gap shifted back to the single-crystal value. All the ZnO thin films studied show strong band-edge photoluminescence. X-ray diffraction measurements showed that samples deposited at low temperatures (<450°C) consisted of amorphous and crystalline phases. The redshift of the optical band gap back to the original position after annealing was strong evidence that the blueshift was due to an amorphous phase. The unshifted photoluminescence spectra indicated that the luminescence was due to the crystalline phase of ZnO, which was in the form of nanocrystals embedded in the amorphous phase.

An inverted organic solar cell employing a sol-gel derived ZnO electron selective layer and thermal evaporated MoO3 hole selective layer

Abstract: We reported an efficient inverted bulk-heterojunction [regioregular of poly(3-hexylthiophene): (6,6)-phenyl C61 butyric acid methyl ester] solar cell with a highly transparent sol-gel derived ZnO film as electron selective layer and MoO3 as hole selective layer. By modifying the precursor concentration of sol from 0.75 to 0.1M, the optical transmittance of ZnO film increases from 75% to 95%. This improvement in transmittance increases the short-circuit density of inverted solar cell from 5.986 to 8.858 mA/cm2 without sacrificing the open-circuit voltage and fill factor of the device. We also demonstrated that the device incorporated with MoO3 has a larger open-circuit voltage and fill factor than the device without MoO3. Power conversion efficiency of 3.09% was achieved under simulated AM 1.5G illumination of 100 mW/cm2.

Optical properties of epitaxially grown zinc oxide films on sapphire by pulsed laser deposition

Abstract: ZnO thin films were epitaxially grown on c-sapphire substrates by pulsed laser deposition at substrate temperatures of 500–800 °C. The crystal structure of ZnO films follow the epitaxial relationship of (0001)ZnO∥(0001)Al2O3(1010)ZnO∥(1120)Al2O3. Both room temperature and cryogenic temperature photoluminescence showed a remarkable band-edge transition, and clear excitonic structures could be seen at cryogenic temperature. The optical refractive index was measured in the range of 375–900 nm by varying angle spectroscopic ellipsometry. The simulation was carried out using a Sellmeier equation.

Zinc oxide nanocomb biosensor for glucose detection

Abstract: Single crystal zinc oxide nanocombs were synthesized in bulk quantity by vapor phase transport. A glucose biosensor was constructed using these nanocombs as supporting materials for glucose oxidase (GOx) loading. The zinc oxide nanocomb glucose biosensor showed a high sensitivity (15.33μA∕cm2mM) for glucose detection and high affinity of GOx to glucose (the apparent Michaelis-Menten constant KMapp=2.19mM). The detection limit measured was 0.02mM. These results demonstrate that zinc oxide nanostructures have potential applications in biosensors.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.