Cerium-europium double activated terbium aluminum garnet phosphor for led application

Abstract

Y3Al5O12:Ce3 (YAG:Ce) and Tb3Al5O12:Ce3 (TAG:Ce) both show the typical Ce3 ion luminescence of the allowed Ce3 d–f transition. Eu3 codoping, however, reveals different results for both matrices: in YAG:Ce, Eu only the luminescence of the Ce3 ion occurs by excitation within the Ce3 absorption bands, because the Eu3 luminescence cannot be sensitized by the Ce3 ion. In TAG:Ce, Eu, both Ce3 and Eu3 luminescence was measured at different Ce and Eu activator concentrations. It is not surprising as an energy transfer from Tb3 to Ce3 and Eu3 is well known in literature. In addition, an excitation in the lowest 5d level of Ce 3 delivers Eu3 luminescence at room temperature. This means that the Ce3 ion can be used as a sensitizer in the TAG lattice that transfers its energy via the Tb sublattice to the activator Eu3 . Application of TAG:Ce, Eu with improved CRI in LED device is demonstrated.