Stability and Optical Properties of ZnO Nanoparticles Capped by ZnS.

ZnO nanoparticles were grown by decomposing of zinc acetate dehydrate. ZnS shells formed on ZnO nanoparticle surfaces in Na2S aqueous solution with the help of ultrasonic at room temperature. The nanoparticle structures and optical properties were characterized. Stability of the shells and effects of capping on the nanoparticle optical properties were studied. Luminescence of the nanoparticles was sensitive to the shell structures and excitation laser density. Single crystal shells could enhance ZnO nanoparticle emission more obviously under higher excitation, but the suppression of the green emission depended on the shell thickness. Single crystal shell could suppress while nanoparticle shells enhance the interface defect vibration. ZnS nanoparticle shells were unstable under exposure to laser light. [ABSTRACT FROM AUTHOR]