Luminescence properties of color-tunable zinc-codoped alikali earth sulfide phosphor for LED application

Zn2+-codoped alikali earth sulfide, (Sr, Ca, Zn)S:Eu2+, was synthesized by a solid-state reaction. The synthesized phosphor was efficiently excited in a broad spectral range from 400 to 500 nm, and exhibits a strong and broad-band red emission. Zn2+-codoping greatly enhanced the emission of this sulfide phosphor. By adjusting the ratio of Sr2+ to Ca2+ in the host, the emission wavelength could be tuned in a range of 606-645 nm. Red and white LEDs were fabricated with this phosphor and blue chips. The red LED shows a high color purity of 92%, while the white LED has CIE coordinates, T-c and R-a of (0.4051, 0.3841), 3450 K, and 80, respectively. (C) 2012 Elsevier B.V. All rights reserved.