Emission of White Light from Doped and Undoped Oxide Nanopowders

Abstract

We have obtained white light (WL) with high efficiency and color rendering index (CRI) approaching the theoretical limit. We report the production of a broad band (ranging from 400 to 900 nm) WL following the monochromatic infrared light (803.5 and 975 nm) excitation of both nominally un-doped and rare earth and transition metal ions-doped oxide nano-powders. Experimental results indicate that such an emission feature is a nano-scale phenomenon, cannot be ascribed to an overlap of sharp emission bands in the un-doped case and, even if assisted by the dopant presence, is a host matrix-related process. The spectral distribution of the detected WL resembles very closely that of an incandescent lamp, which in turn is the most comfortable light to human eyes. Our experimental results make our WL emission very interesting at both the fundamental and the applicative level and may open the way to an alternative route with respect to incandescent lamps.