ZnO coated nanoparticle phosphors

Conventional phosphor materials are doped ternary or quaternary compounds; hence it would be difficult to prepare nanoparticles of those materials by build up methods. Ba₂ZnS₃:Mn (BZS), SrGa₂S ₄:Eu, and BaAl₂S₄:Eu nanoparticles were prepared by a break down method, namely the ball-milling method. Transmission electron microscopy (TEM) and TEM- energy-dispersive X-ray spectroscopy (EDX) measurements showed several-nanometer-size stoichiometric and dispersed nanoparticles were achieved. ZnO-coating was performed and the uniform coating layers were formed on the phosphor nanoparticles. The ZnO-coated nanoparticles exhibited an improved stability in Photoluminescence. Red color phosphor material, namely BZS, was ball-milled and sprayed on the glass substrate. Mn doped BZS absorbs ultra violet light and emits red light peaking at around 640nm. When the single crystal Si solar cell was placed under the transparent nanoparticle layer, short wavelength light was absorbed and converted to long wavelength light.