Fabrication and photoluminescence of ZnS:Mn2+ nanowires/ZnO quantum dots/SiO2 heterostructure

In this paper, we demonstrated the encapsulation of ZnS:Mn(2+) nanowires (NWs) and ZnO quantum dots (QDs) with a layer of mesoporous SiO(2) shell for the purpose of integrating dual emission property into one common nanostructure. The average diameter of ZnS:Mn2+ NWs, ZnO QDs, and ZnS:Mn(2+)/ZnO@SiO(2) heterostructure was about 10 nm, 6 nm, and 22 nm, respectively. Within ZnS:Mn(2+)/ZnO@SiO(2) nanocomposites, the intensity of the yellow-orange emission contributed by ZnS:Mn(2+) NWs and the UV emission contributed by ZnO QDs was three and ten times higher than their individual components, respectively. The fluorescence intensity ratio of the dual emission can be tuned by adjusting the hydrolysis time of tetraethyl orthosilicate. The peak energy of the yellow-orange and UV emission showed blueshift and redshift as increasing the temperature, respectively. The anomalous enhancement of the integrated intensity for the UV emission with the temperature indicated that the high surface state density existing in ZnO QDs can overrun the influence of temperature quenching and even alter the photoluminescent properties. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467762]