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, Tc and Ra of (0.4051, 0.3841), 3450 K, and 80, respectively.

► Excitation of (Sr, Ca, Zn)S: Eu2 + was suitable for blue LED.
► Zn2 +-codoping greatly enhanced the emission of this sulfide phosphor.
► The emission wavelength can be tuned in range of 606–645 nm with different Ca2 + content.
► The prototype red LED has a high color purity of 92%.
► The white LED has a CIE coordinate, Tc and Ra of (0.4051, 0.3841), 3450 K, and 80.