Germanate glasses co-doped with Ce3+/Ln3+ (Ln = Pr, Tb, Dy) for white light emitting diodes

Glasses doped with lanthanides ions may be good white light emitters due to their interesting physical and spectroscopic properties. In this paper, the optical spectroscopy of rare earths doped glasses with a special emphasis on application as white LED were presented. The luminescent glass materials containing Ln³⁺ (Ln = Pr, Tb, Dy) and Ce³⁺ ions were obtained. The glasses samples were prepared by a traditional melt-quenching technique. The optical properties of glasses containing various concentrations of rare earth ions were analyzed. It was observed that luminescence bands corresponding to characteristic transitions of Ln³⁺ and cerium ions are present on spectra measured under direct excitation of Ce³⁺. Therefore, it indicates that the energy transfer process between Ce³⁺ /Pr³⁺, Ce³⁺ /Tb³⁺, Ce³⁺ / Dy³⁺ ions in glasses occurs. Some parameters such as correlated color temperature (CCT) and chromaticity coordinates (CIE) that characterize white LEDs were analyzed and discussed in detail.