High-brightness red-emitting Eu3+-activated Ca2LuZr2Al3O12 garnet phosphors with excellent thermal stability for near-UV-pumped white LEDs

Abstract

In this work, a group of red-emitting Ca2LuZr2Al3O12:xEu3+ (x = 20%, 30%, 40%, 50%, 60%, 70% and 80%) phosphors have been prepared and their luminescence properties are studied. X-ray diffraction, excitation and emission spectra, fluorescence decay curves, CIE color coordinates, and temperature-dependent photoluminescence spectra are used to characterize these samples. All these Ca2LuZr2Al3O12:Eu3+ compounds exhibit intense red luminescence peaking at around 618 nm under 394 nm excitation. The critical concentration of Eu3+ ion is 50 mol%, and the concentration quenching mechanism has been discussed and analyzed. The CIE color coordinates of the optimal Ca2LuZr2Al3O12:50%Eu3+ sample are (0.6506, 0.3487), and it has a high color purity of 90.7%. Importantly, the emission intensity of Ca2LuZr2Al3O12:50%Eu3+ is about 1.67 times higher compared to the commercial Y2O3:Eu3+ red phosphor. What's more, Ca2LuZr2Al3O12:50%Eu3+ phosphor also displays excellent resistance to thermal quenching at elevated temperature; only 14% emission intensity is lost at 150 °C.