Synthesis and optical properties of yellow emitting garnet phosphors for pcLEDs

A series of CaY2Al4SiO12:Ce3+ garnet-type luminescent materials was prepared by a sol–gel combustion technique. All samples were characterized by powder X-ray diffraction (XRD), thermal quenching (TQ), fluorescence lifetime, and photoluminescence (PL) measurements. Moreover, luminous efficacies (LE), CIE 1931 color points, and quantum efficiencies (QE) were calculated and discussed. XRD patterns indicated that sintering at 1450 °C yielded single phase garnets. Phosphors showed a broad band emission in the range 460–750 nm. The emission band maximum is blue-shifted in comparison to Y3Al5O12:Ce3+ and shifts from 542 to 560 nm by increasing the Ce3+ concentration. The highest achieved QE was 86% for the sample doped with 0.25% of Ce3+. Higher Ce3+ doping levels resulted in concentration quenching.