Effect of co‐doping of Ce 3+ and alkaline metals on the photoluminescence in CaGa 2 S 4 and SrGa 2 S 4 hosts

Ce 3+ doped alkaline‐earth thiogallates represented as M II Ga 2 S 4 (M II = Ca, Sr, Ba) are known as blue phosphors with high brightness and good purity of color. However the Ce concentration is limited below about 1 mol% in the process of the single crystal growth, presumably due to the charge imbalance of the dopant. Here in order to increase Ce 3+ concentration, alkaline metals and Ce ions are codoped in the alkaline earth thiogallates and the effect of co‐doping on the photoluminescence is studied. More than 15 mol% Ce doping is achieved, and PL intensity in Na codoped Ca and Sr thiogallates becomes three and five times stronger than that of the only Ce 3+ 1 mol% doping case, respectively. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)