Enhanced photoluminescence emission and thermal stability in diamond-like framework contained K(Sr, Ba)BP2O8:Eu3+red phosphors via composition modification

The development of the phosphors with an excellent emission thermal stability is of great interest in the phosphor-converted WLEDs. Herein, we study the electronic structures of KMBP2O8 (M = Sr, Ba) and the luminescence properties of the diamond-like framework contained K(Sr, Ba)BP2O8:Eu3+ phosphors. The calculation results indicate KSrBP2O8 and KBaBP2O8 are indirect band gap materials. The study of the luminescence properties of KSr0.96(1-y)Ba0.96yBP2O8:0.04Eu(3+) indicates that the emission intensity and the R/O value have been improved with the increasing of Ba2+ until y= 0.3. Furthermore, the temperature dependent experiment implies that the value of the thermal activation energy has been enhanced until y = 0.5, while it will decrease by the further increasing of Ba2+. The improvement of the thermal stability of Eu3+ and Ba2+ codoped KSrBP2O8 should mainly attribute to the low defect formation energy because of the repulsion of Eu3+ at smaller Sr sites after the Ba substitution in KSrBP2O8:Eu3+ phosphor. Therefore, the introducing of the extra ions to result in the repulsion of luminescence centers within the host lattice is thus shown to be an effect method to increase the emission intensity and suppress thermal quenching. The results will supply the fundamental data for improving the performance of the phosphors in WLED devices.