ENHANCED LIGHT EXTRACTION FROM COLLOIDAL ZnO QD FILM BY ADDING ON PHOTONIC CRYSTALS USING UV-NANOIMPRINT LITHOGRAPHY

A significant enhancement in light extraction from colloidal ZnO QD films was observed on an addition of a layer of two-dimensional photonic crystal (2D-PC) structure. The PCs with a rectangular-lattice air-hole array pattern with the period of 1.4 μm and the hole-size of 400 nm were fabricated by UV-nanoimprint lithography (UV-NIL). Unlike the commonly utilized electron-beam lithographic technique, the UV-NIL process can make patterns over a large area with high throughput. The resultant colloidal zinc oxide (ZnO) QD films with a PC pattern add-on had nearly double the output power, as measured from the top of the film.