Enhanced red emission in ZnB2O4:Eu3+ by charge compensation

Eu3+ doped ZnB2O4 without or with different charge compensation (CC) approaches (co-doping Li+, Na+, K, decreasing the content of Zn2+) were prepared by solid state reactions. The phosphors can strongly absorb 393 nm ultraviolet (UV) light which is coupled well with the emission of currently used InGaN-based near UV light emitting diodes (LEDs) and emit red light with a good color purity. The luminescent intensity of phosphors can be remarkably enhanced with any of CC methods. However, the shape and position of excitation and emission spectra keep unchanged. The introduction of Li+ can enhance the red emission intensity of Eu3+ by ∼4 times with the optimal effect. Red emission of Eu3+ can also be enhanced with the other three CC approaches but the effects are not as good as Li+ because the volume unbalance in Li+ compensation approach is the smallest while net positive charge was offset. The results of this work suggest that volume compensation and equilibrium of mole number should also be taken into account when a CC approaches is selected.

► The introduction of Li+ in Eu3+ doped ZnB2O4 can enhance the red emission intensity of Eu3+ by ∼4 times.
► Volume compensation should also be taken into account when a charge compensation method is selected.
► The emission intensity of Eu3+ increases with the increasing crystallinity of the host.