WO3-ZnO and CuO-ZnO nanocomposites as highly efficient photoanodes under visible light illumination.

We prepared ZnO nanocomposites with WO3 or CuO nanostructures to improve the photocatalytic performance of ZnO nanostructures. Characterization of the nanocomposites using scanning electron microscopy, x-ray diffraction, UV-vis spectrometry and photoluminescence revealed the morphologies and wide light absorption range of the materials. The highest current densities of WO3/ZnO and CuO/ZnO nanocomposites were 1.28 mA cm-2 and 2.49 mA cm-2 at 1.23 V (versus a reversible hydrogen electrode) under AM 1.5 100 mW cm-2, which are ~1.2- and 3.5-fold greater than those of bare ZnO nanostructures, respectively. The easy fabrication process suggests that nanocomposites with narrow bandgap materials, such as WO3 and CuO, will improve the performance of electrochemical and optoelectrical devices such as dye-sensitized solar cells and biosensors.

Light Absorption and Luminescence Quenching Properties of Hybrid Bulk Heterojunction Materials Based on the Blend Conducting Polymers.

We have investigated the enhancement absorption light and luminescence quenching properties of the hybrid bulk heterojunction systems which were fabricated using poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV); poly(3-hexylthiophene) (P3HT); fullerene derivative 1-(3-methoxycarbonyl) propyl-1-phenyl-[6,6] C61 (PCBM) and TiO2 nanocrystals. The optimized material showed a broad absorption in the region of 350 to 670 nm and the luminescence quenching higher 85%. The obtained results provide further insight into photophysics of the heterojunction system and device performance improvement by using this system as an active layer.

Application of solution-processed metal oxide layers as charge transport layers for CdSe/ZnS quantum-dot LEDs.

We fabricated and characterized quantum-dot light emitting devices (QLEDs) that consisted of a CdSe/ZnS quantum-dot (QD) emitting layer, a hole-transporting nickel oxide (NiO) layer and/or an electron-transporting zinc oxide (ZnO) layer. Both the p-type NiO and n-type ZnO layers were formed by using sol-gel processes. All the fabricated CdSe/ZnS QLEDs showed similar electroluminescence spectra that originated from the green CdSe/ZnS QDs. However, different combinations of hole- and electron-transporting layers resulted in efficiency variations. In addition to the control of the respective concentrations of holes and electrons within a multilayer device structure, which determines the luminance and efficiency of QLEDs, the use of metal oxide layers is advantageous for long-term stability of QLEDs because they are air stable and can block the permeation of water vapor and oxygen in ambient air to a QD emitting layer. Moreover, the wet chemistry processing for their formation makes metal oxide layers attractive for low cost and/or large area manufacture of QLEDs.