On the combination of praseodymium and cerium, a new concept of improving orange-red luminescence

A new concept of obtaining red emission in solid-state LED devices based on material composition was proposed. Gd3Ga5O12 (GGG) luminescent compounds doped with both Pr3+ and Ce3+ ions were synthetized. Positions of f-d bands were assigned. Increase of the 1D2 praseodymium red luminescence intensity following the increase of Ce3+ concentration was observed. However, participation of the energy transfer from d levels of Ce3+ to Pr3+ was ruled out. Decay curves of the luminescence originating from the 1D2 and 3P0 multiplets in both GGG:Pr and GGG:Pr + Ce were analyzed as the function of dopants concertation. For diluted Pr3+ they reach ca. 230 and 24 μs Nonexponential character of Pr3+ decay curves was observed. The concentration quenching mechanisms were determined. The quadrupole-quadrupole mechanism of changing the emission color to orange-red in Ce + Pr system may suggest that in this process, more than one of cerium ions take part simultaneously.