Broad Green Emission in the Leucite-Like Cs2ZnSi5O12:Eu2+ Phosphor

Cesium zinc silicate substituted with Eu2+ has been synthesized as a new green-emitting phosphor with potential application in UV-based solid state white lighting. Cs2ZnSi5O12 has been known to exhibit polymorphism, crystallizing in space group Pbca as well as Pa (3) over bar, as a structural analog to the cubic leucite, CsAlSi2O6. Using laboratory X-ray powder diffraction and optical spectroscopy, the crystal structure of Cs2ZnSi5O12:Eu2+, when prepared using high-temperature ceramic synthesis, was confirmed to adopt space group Pa (3) over bar. This novel phosphor produces a broad green emission (lambda(em) = 504 nm) upon UV excitation. Encapsulating the compound in optically transparent silicone resin along with the red-emitting Sr2Si5N8:Eu-2+ and exciting with a UV-LED (lambda(ex) = 370 nm) produces a warm white light with excellent color rendering. The advantage of developing a light using Cs2ZnSi5O12:Eu2+ is that the broad green emission negates the need for incorporating three different phosphors as is commonly required for UV-pumping. This dramatically simplifies device design while still achieving high-quality UV-based white light. Once the emission efficiency and thermal stability of Cs2ZnSi5O12:Eu2+ is improved, there can be seamless integration with UV-LEDs for high-quality warm white light production. (C) The Author(s) 2019. Published by ECS.