Improved NIR emission from Tb3+, Yb3+ and Nd3+ co-doped La2O3 nano-phosphor

NIR and visible emission have been reported from Tb3+, Yb3+ and Nd3+ doped La2O3. XRD, TEM and HRTEM corroborate good crystallinity of the nano-phosphor. The average particle size is around 15 nm examined via TEM and HRTEM. The photoluminescence up-conversion spectra of Tb3+ and Yb3+ co-doped La2O3 exhibited characteristic emission peaks of Tb3+ ion at 480, 544 and 610 nm. It is possible due to the absorption of two 980 nm pump photons by Tb3+ ion via Yb3+ sensitizer. The energy migration from Tb3+ to Nd3+ takes place so that the intensity of 820 nm (F-4(5/2), H-2(9)/2 -> I-4(9/2)) is increased significantly. The energy transfer between these two ions reduces the intensity of 544 nm Tb3+ ion whereas the intensity of 820 nm improved. Energy transfer mechanism between Tb3+, Nd3+ and Yb3+ ions has been discussed in detail. It would be a promising candidate for solar cells and biomedical applications.