Enhanced Luminescence in Tb/Ce co-doped Zinc- and Tin-Oxide quantum dots

SnO$_2$ and ZnO quantum dots doped with Tb$^{3+}$ exhibit strong luminescence from the Tb$^{3+}$ dopants due to efficient energy transfer from the semiconductor donors to the Tb$^{3+}$ acceptor ions. We report results from a study of the effect of co-doping the SnO$_2$ and ZnO dots with both Tb$^{3+}$ and Ce$^{3+}$ on the photoluminescence properties of the samples. The dots were synthesized using a sol-gel technique and the Ce$^{3+}$/Tb$^{3+}$ ratio was varied while keeping the total doping level at 1wt$\%$. X-ray diffraction and TEM results confirm the presence of nanocrystals of less than 10 nm in diameter. Photoluminescence results indicate that the Tb$^{3+}$ ions are incorporated in a crystalline environment and that co-doping with Ce$^{3+}$ enhances the energy transfer efficiency and therefore the intensity of the Tb$^{3+}$ luminescence. The effect of heat treatment on the size of the dots and the impact of size on luminescence properties was also investigated.