A novel red-emitting phosphor Mg2Y2Al2Si2O12:Ce3+/Mn2+ for blue chip-based white LEDs

Traditional white light-emitting diodes (LEDs) (blue chip + YAG:Ce3+ yellow phosphor) have the limitation of red deficiency, which limits their application in the illumination field. The single cation/anion substitution or co-doping of activators can increase the red component; however, the large energy loss is attributed to the ultra-long Stokes shift and energy transfer. This work attempts to utilize the short-distance Stokes shift and a small amount of energy transfer to increase the red component in two steps. First, based on a large number of previous research results, the Mg2Y2Al2Si2O12:Ce3+ phosphor is selected. Second, additional enhancement of the red component in the emission spectrum was achieved by ion co-doping Mn2+ into Mg2Y2Al2Si2O12:Ce3+. The emission peaks for samples Mg2Y2Al2Si2O12:Ce3+,Mn2+ shift from 600 to 635 nm with increase in the concentration of Mn2+, and the emission spectra intensity of Mg1.97Y1.93Al2Si2O12:0.07 Ce3+,0.03 Mn2+ anomalously increased by similar to 37%, which was attributed to the increase in the distance between Ce3+ ions because of the doping of Mn2+ ions, and reduction in the concentration of defects in the crystal, resulting in the energy loss decreases of Ce3+. The emission peak of Mg1.97Y1.93Al2Si2O12:0.07 Ce3+,0.03 Mn2+ shifts to 618 nm and the quantum efficiency was as high as 83.07%. Furthermore, this sample has high thermal stability and the emission intensity was still 80.14% at 120 degrees C. As such, it has great potential in the application of white LEDs.

Automated summary

This study improved the composition of the phosphor to enhance the red component while increasing the spectral intensity and quantum efficiency, and also improved the thermal stability of the crystal, showing great potential for application in white LEDs.