Mingqiu Zhang

Structural and lasing characteristics of ultrathin hexagonal ZnO nanodisks grown vertically on silicon-on-insulator substrates

Hexagonal ZnO nanodisks were grown on silicon-on-insulator substrates by vapor-transport method without catalysts. The resulting nanodisks possess ultrathin thickness (10–20nm) and most of them present vertical orientation on the substrate surface. Under optical excitation, these ultrathin nanodisks exhibit ultraviolet lasing emission with the excitation threshold of 205μJ∕cm2 and emission lifetime of 2ps at room temperature. The detailed lasing analysis indicates that whispering-gallery-mode lasing may occur in the ZnO nanodisks.

Fabrication and characterization of PbS/multiwalled carbon nanotube heterostructures

PbS quantum dots/multiwalled carbon nanotube (PbS/MWCNT) heterostructures were fabricated via a simple wet-chemical method. The structural and optical properties of as-prepared samples were characterized by transmission electron microscopy, x-ray diffraction, micro-Raman, and photoluminescence spectroscopies. It was found that the size, shape, and coverage density of the PbS quantum dots on the MWCNT can be controlled through varying synthesis conditions. Photoluminescence spectrum revealed that the emission of the PbS quantum dots was partially quenched when they were coupled to the MWCNT. This suggests that the photoinduced charge transfer may occur between the PbS and the MWCNT.

Enhanced photoresponse of CdS/CMK-3 composite as a candidate for light-harvesting assembly

Two typical carbon materials (ordered mesoporous carbon and carbon nanotube) were chosen as scaffolds in combination with semiconductor quantum dots (SQDs) for making light-harvesting assemblies. The effects of interfacial morphology on photoelectric performance of the carbon-based heterostructures have been investigated in detail. The enhanced photoresponse shows a strong dependence on the interfacial morphology as a result of direct interfacial contacts between SQDs and carbon materials, which plays a major role in increasing charge generation at the interface and transport pathways for photoinduced electron transfer. The methodology to enhance the photoresponse through tuning interfacial morphology proves to be a potent alternative in fabricating photochemical energy conversion systems.

Optical properties of synthesized organic nanowires

Organic nanowires have been synthesized by hydrothermal method. The functional groups in chemical structure of the organic nanowire have been characterized by Fourier-transform infrared spectrum. Optical properties of organic nanowires have been demonstrated by linear absorption, photoluminescence spectroscopy, and time-resolved photoluminescence spectroscopy. Two emission peaks at 3.91 and 3.3eV have been revealed by fluorescence spectrum at room temperature. For the emission peak at 3.3eV, a blueshift occurred when the temperature rises. Two time components have been observed in fluorescence dynamic process of the nanowire by time-resolved decay curve.