Synthesis and optical properties of green to orange tunable garnet phosphors for pcLEDs

Y3−xLuxAl3MgSiO12:Ce3+ phosphors were prepared by aqueous sol–gel technique. Samples with 0.25, 0.5, 0.75 and 1 mol-% of Ce3+ were fabricated and characterized by powder X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, and temperature dependent luminescence to reveal the thermal quenching. Moreover, luminous efficacies (LE), CIE 1931 color points and quantum efficiencies (QE) were calculated and discussed. XRD patterns confirmed the presence of single phase garnet for all samples independent of Ce3+ concentration and Y/Lu ratio. Phosphors showed broad band emission in the range 500–750 nm. The emission maximum shifts from 555 to 585 nm depending on the Ce3+ concentration and Y/Lu ratio. Quantum efficiency of the phosphors decreased with rising Ce3+ concentration and increased with increasing Lu content.

Research highlights
► Incorporation of Mg2+–Si4+ pair into garnets leads to red-shift of Ce3+ emission.
► Stronger thermal quenching is observed if emission is red-shifted.
► Quantum efficiency decreases if Ce3+ concentration is increased.