Z.H. Huang

Dye-sensitized solar cell with a titanium-oxide-modified carbon nanotube transparent electrode

Transparent and conductive carbon-based materials are promising for window electrodes in solid-state optoelectronic devices. However, the catalytic activity to redox reaction limits their application as a working electrode in a liquid-type dye-sensitized solar cell (DSSC). In this letter, we propose and demonstrate a transparent carbon nanotubes (CNTs) film as the working electrode in a DSSC containing iodide/triiodide redox couples. This implementation is realized by inhibiting the charge-transfer kinetics at CNT/redox solution interface with an aid of thin titanium oxide film that facilitates the unidirectional flow of electrons in the cell without sacrificing the electrical and optical properties of CNT.

Analysis of fractal characteristics of fractured surfaces by secondary electron line scanning

Abstract Fractal characteristics of impact-fractured surfaces at room temperature for CK45 steel under different heat treatment conditions were investigated by means of secondary electron line scanning, and the results were compared with those obtained by the profilometric method. It was found that the value of the fractal dimension Dse obtained from secondary electron line scanning analysis is larger than that from vertical section analysis (Dvs) for the same fractured surface. However, Dse, Dvs and the impact toughness of the material vary with tempering temperatures in a similar manner. The profile of the secondary electron scanning line can reflect the angular distribution of the scanned surface but cannot directly express the outline of its vertical section.

Enhanced electrochemical oxidation of phenol using a hydrophobic TiO2-NTs/SnO2-Sb-PTFE electrode prepared by pulse electrodeposition

In this study, novel Sb-doped SnO2 electrodes with a polyetrafluoroethylene (PTFE) composite were fabricated by pulse electrodeposition. In this process, vertically aligned TiO2 nanotubes (TiO2-NTs) formed by anodization of Ti plates served as the substrate for SnO2 eletrodeposition. Comparing with the conventional SnO2-Sb electrodes, TiO2-NTs/SnO2-Sb-PTFE electrodes have higher oxygen evolution potential, improved surface hydrophobicity, superior hydroxyl radical (HO˙) generation and enhanced electrocatalytic activity by incorporation of PTFE nanoparticles. Field emission scanning electron microscopy (FESEM) shows that the surfaces of the PTFE composite electrodes exhibit a microspherical structure. Energy-dispersive X-ray spectroscopy (EDS) confirms the uniform distribution of Sn, Sb, F and C on TiO2-NTs/SnO2-Sb-PTFE surfaces. More importantly, the electrodes exhibit a distinctive improvement of oxygen evolution potential (OEP) from 2.0 to 2.4 V (vs. Ag/AgCl). The electrochemical impedance of TiO2-NTs/SnO2-Sb-PTFE also decreases significantly compared with Ti/SnO2-Sb(conventional). The electrocatalytic performance of TiO2-NTs/SnO2-Sb-PTFE compared with Ti/SnO2-Sb(conventional) and TiO2-NTs/SnO2-Sb were investigated using phenol as the model pollutant. The effects of initial solution pH and types of supporting electrolyte were investigated. The removal efficiency of total organic carbon (TOC), specific UV absorbance at 254 nm (SUVA254), mineralization current efficiency (MCE) and energy consumption (Ec) with respect to different PTFE loadings on the electrodes were investigated. The anodic leaching of Sn ions was also studied under different conditions.

Investigations of enhanced device characteristics in pentacene-based field effect transistors with sol-gel interfacial layer

Pentacene films grown on sol-gel silica dielectrics showed a significant enhancement in field effect mobility, threshold voltages, and subthreshold swings. This letter investigates the contributing factors for the enhanced device characteristics. The smoother and more hydrophobic film surfaces of sol-gel silica (rms roughness of ∼1.9A and water contact angle of ∼75°) induced larger pentacene grains, yielding mobilities in excess of ∼1cm2∕Vs at an operating voltage of −20V. Different sol-gel silica film thicknesses showed similar trends in improved performances, indicating that this phenomenon is clearly a semiconductor-dielectric interface phenomenon rather than a bulk dielectric effect.

A study of the slit island analysis as a method for measuring fractal dimension of fractured surface

huang, zh (reprint author), acad sinica,inst met res,fatigue & fracture mat lab,wenhua rd 72,shenyang 110015,peoples r china

Effect of arrangement of acicular ferrite in a Widmanstatten microstructure on the fracture of mild steel

Abstract The effect of the morphology and distribution of ferrite, especially acicular ferrite in a Widmanstatten structure, on the fracture behaviour of mild steel at low temperatures is discussed in detail. The microstructures of polygonal ferrite, intersecting acicular ferrite and parallel acicular ferrite were obtained using an interrupted cooling procedure, and the different effects on the fracture toughness at low temperature were found. If an intersecting acicular ferrite microstructure is present, then the steel has superior toughness at low temperature in comparison with that of polygonal ferrite. If the microstructure is mainly composed of parallel acicular ferrite, however, the steel toughness is comparable to that of polygonal ferrite.

Electrochemical Treatment of ITO Surface for Performance Improvement of Organic Light-Emitting Diode

Electrochemically modified indium-tin oxide (ITO) surfaces were used as hole injection electrodes in organic light emitting devices. Substantial improvement in hole injection and electroluminescence efficiencies were observed in devices with the sample configuration of ITO/NPB/Alq 3 /LiF/Al. The turn-on voltage reduced from 5.3 V for device with pristine ITO to 2.8 V for device with ITO pretreated electrochemically at +2.4 V in K 4 P 2 O 7 electrolyte. The current and power efficiencies at 20 mA/cm 2 were increased correspondingly from 3.0 cd/A and 0.84 lm/W to 3.4 cd/A and 1.24 lm/W. The mechanisms behind this performance enhancement were discussed.

Comments on some of the fractal equations

Abstract The fractal equations or relationships used to measure the fractal dimension of a fractured surface are discussed and several suggestions are made to modify them.

A novel method for fabrication of integrated shadow mask for patterning electrode in passive matrix OLED displays

This paper reports a novel method for making an integrated shadow mask used in fabrication of passive matrix OLED displays. Common positive and negative photoresists were employed to produce retrograded strip pillars with large overhang and undercut by photolithography. The pillar strips serve as an effective shadow mask for patterning the organic layers and the metal cathodes in OLED display devices. It is expected that this method can significantly enhance the performance of passive matrix OLED at a low shadow mask fabrication cost. The method can be used for fabricating more complicated structures for other display applications.

Study of irregular surfaces by secondary electron line scanning

Abstract Secondary electron line scanning (SELS) and its relationship with the corresponding topography of rough surfaces have been investigated in detail. It is found that the SELS image is more effective for describing the angular distribution of a rough surface than the corresponding profile outline (or vertical section); however, no strict mathematical relationship exists between the SELS image and the profile outline. We have also found that SELS can be used to measure directly the surface roughness of a fractured surface and gives similar results to those calculated using a stereological equation linking the surface roughness parameter to the profile roughness parameter; this suggests a new method for quantitative study of fractured surfaces.