Luminescence properties of Tb3+–Sm3+ codoped glasses for white light emitting diodes

Photoluminescence properties of silicate and borosilicate glasses codoped with ${\mathrm{Tb}}^{3+}$ and ${\mathrm{Sm}}^{3+}$ ions have been characterized by excitation and emission spectroscopies. When excited by ultraviolet light the glasses emit a combination of green and orange-red wavelengths giving white light. The ratio of the intensities of orange-red to green emissions can be tuned by varying both the concentration of the ${\mathrm{Sm}}^{3+}$ ion and an the composition of the glass matrix. The excitation and emission spectra show a self-quenching effect for the ${\mathrm{Sm}}^{3+}$ ions and an energy transfer from ${\mathrm{Tb}}^{3+}$ $\left({}^{5}D_4\right)$ to ${\mathrm{Sm}}^{3+}$ $\left({}^{4}G_{5∕2}\right)$ .