High-efficiency and thermal-stable Eu3+-activated Ca3Y(AlO)3(BO3)4 red-emitting phosphors for near-UV-excited white LEDs

Abstract

Red-emitting Ca3Y(AlO)3(BO3)4:Eu3+ (abbreviated as CYAB:Eu3+) phosphors with different Eu3+ doping concentrations were synthesized by a conventional solid-state method and their crystal structure, morphology, luminescence properties, decay curves and quantum efficiency were investigated in detail. The CYAB:Eu3+ phosphors can emit red light peaking at ∼ 621 nm under 397 nm excitation and the most intense red emission was obtained at the Eu3+ concentration of 50 mol%. From the concentration-dependent photoluminescence studies of CYAB:Eu3+ phosphors, the concentration quenching mechanism was dominated by dipole-dipole interaction. The as-prepared CYAB:0.5Eu3+ sample possessed good color coordinates of (0.653, 0.342) with high color purity of 90%. More importantly, the internal quantum efficiency of CYAB:0.5Eu3+ sample reached up to 88%. Furthermore, CYAB:Eu3+ exhibited good thermal stability and its emission intensity at 150 °C was still up to 76.3% of that at room-temperature. In addition, a prototype LED device was fabricated by coating a phosphor blend of BaMgAl10O7:Eu2+ blue phosphors, (Ba,Sr)2SiO4:Eu2+ green phosphors and CYAB:0.5Eu3+ red phosphors on the surface of 395 nm-emitting InGaN chip, which exhibited bright white light under 120 mA driven current. These good results indicate that the CYAB:Eu3+ phosphors are very appropriate red-emitting phosphors for applications in near-ultraviolet-excited white light-emitting diodes.