Colour tuning of garnet phosphor through codoping

Abstract

Ca3Sc2Si3O12:Ce3+ is a well known green emitting phosphor for two phosphor converted LED lamp. It is shown that the emission colour can be tuned with the help of various co-dopents. For obtaining safer cyan emitting phosphor, partial substitution of Si by Ge found to be effective. Pr codoping is responsible for the addition of red component. The partial substitution of Y at Ca site and Mg at Sc site is the novel step into the work. This substitution converts the cyan emitting phosphor into yellow one. The colour changes are illustrated by calculating colour coordinates. Na codoping facilitates incorporation of the trivalent activator at Ca2+ site, as well as the grain growth, and enhances the PL intensity without changing emission colour. Addition of Cyan emitting phosphor in the blend can be useful for achieving super Colour Rendition Index (CRI > 95). Extended excitation in the violet region will result in removal of the harmful wavelengths from the LED lamp.