F. Kong

Luminescent silicon carbide nanocrystallites in 3C-SiC∕polystyrene films

We report optical emission of SiC nanocrystallite films, which clearly shows the quantum confinement effect. Bulk polycrystalline 3C-SiC was first electrochemically etched and then the fabricated porous silicon carbide was ultrasonically treated in water or toluene suspension to disperse into colloidal nanoparticles. Transmission electron microscopy images clearly show that the colloidal nanoparticles have 3C-SiC lattice structure with sizes varying from about 6nm down to below 1nm. The suspension of 3C-SiC nanocrystallites exhibits ultrabright emission with wavelengths ranging from 400to520nm when the excitation wavelength varies from 250to480nm, in accordance with the quantum confinement effect. By adding polystyrene to the toluene suspension containing SiC nanoparticles and coating the mixing solution onto a Si wafer, we obtain the SiC∕polystyrene films that luminesce.

Optical emission from nano-poly[2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene] arrays

Using an anodic alumina membrane with an ordered nanopore array as a template, we have fabricated a two-dimensional light-emitting nanopolymer array by embedding the luminescence polymer poly[2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene] (MEH-PPV) into the nanopores. It is revealed experimentally that the conformation of the MEH-PPV chains in the nanopores is in the form of a bunch of polymer chains. The number of the polymer chains in a bunch depends on the concentration of the polymer solution and the diameters of nanopores in the template. Investigation on the photoluminescence spectra of the nano-MEH-PPV array annealed under different temperatures shows that the nanopores can effectively hinder the relaxation of MEH-PPV, which leads to its high thermal stability.