On the relationship between emission color and Ce3+ concentration in garnet phosphors

It is known that the emission color of Ce3+ doped garnets is strongly redshifted at higher Ce3+ concentrations. In this report, we study the cause of this redshift in Lu3Al5O12:Ce3+ (LuAG:Ce) phosphors. These changes in emission color with Ce3+ concentration are mainly attributed to a combination of inhomogenous broadening for Ce3+ in LuAG and energy transfer from high energy Ce3+ ions to low energy Ce3+ ions. Evidence for inhomogenous broadening and energy transfer is given through time resolved measurements. Potential reasons for inhomogenous broadening of Ce3+ in these phosphors are also discussed.