Effect of co-doped Tb3+ ions on electroluminescence of ZnO:Eu3+ LED

Rare earth (RE) -doped ZnO electroluminescence is worthy of investigation for phosphor-free white light-emitting diodes (LEDs) due to their pure and sharp emissions. Whereas, the low solubility of RE ions in ZnO films is found to hinder the performance of RE-doped ZnO devices. Herein, ZnO:Eu and ZnO:Eu/Tb LEDs were synthesized and the electroluminescence properties were tested. The results show that the emission intensity of ZnO: Eu/Tb LED is 8 times higher than that of ZnO: Eu LED while the input power is smaller when the concentration of terbium is proper. Furthermore, we discussed the excitation mechanism and found that the ratio of the EL intensity of the D-5(1) -> F-7(1) to D-5(0) -> F-7(J (J=0 - 4)) transition increases with increasing Tb doping concentration, which may indicate the possibility of energy transfer from Tb3+ to Eu3+. The results are believed to be an effective strategy to improve the electroluminescence of RE-doped semiconductor for white LEDs.