Green photolumineseence suppression in ZnO embedded in porous opal

The photoluminescence (PL) and transmittance characteristics of zinc oxide (ZnO) embedded in voids of silicon dioxide synthetic opal by the technologically simple sol-gel method are reported. The uniform formation of ZnO nanoparticles inside of the opal matrix can be obtained after its infiltration in an aqueous solution containing a zinc nitrite hexahydride precursor followed by thermal annealing. The green-PL suppression is observed due to the inhibition of spontaneous emission through oxygen vacancies in ZnO. The strong redshift of the transmittance characteristics signifies the essential filling of voids in the fcc packed structure. The infiltration of nanocrystals into synthetic opal may be used as an inexpensive method for the fabrication of polycrystalline ZnO with dominant ultraviolet-blue PL. This technology may also be promising for the fabrication of color light sources, such as RGB pixels in secondary-electron-emission or field-emission displays.