Synthesis and characterization of highly Eu3+-doped CaY2Sb2(ZnO4)3 red phosphors with abnormal thermal quenching performance for w-LEDs application

In the present work, a series of zincate CaY2Sb2(ZnO4)3:Eu3+ phosphors were successfully obtained via the conventional solid-state method at high temperature. The phase purity, morphology, element mapping, photoluminescence excitation/emission (PLE/PL), and decay time of the obtained phosphors were investigated systematically. Results show that the synthesized samples demonstrate the strongest red-emitting peak at 610 nm under the n-ultraviolet (n-UV) 395 nm excitation. The Judd-Ofelt parameters (Ω2, Ω4), radiative transition rates, and branching ratios (β0J, J = 2, 4) of CaY2Sb2(ZnO4)3:Eu3+ to explore the Eu3+-coordinated environment in the host matrix. The concentration quenching of CaY2Sb2(ZnO4)3:2xEu3+ phosphors happened until at high doping concentration of x = 50 mol%. CaY2Sb2(ZnO4)3:100 mol%Eu3+ sample presented the excellent thermal stability with abnormal thermal quenching behavior. Compared with the commercial Y2O3:Eu3+ red phosphor, the luminescent intensity of the prepared phosphor is 1.14 times stronger. The high internal quantum efficiency (IQE) of CaY2Sb2(ZnO4)3:100 mol%Eu3+ phosphor is 79.20%. In addition, the fabricated red and white light-emitting diodes (w-LEDs) both emit bright light. The w-LED demonstrates a high color rendering index (Ra = 96) and a low correlated color temperature (CCT = 5249 K). Therefore, the prepared red-emitting phosphor has a promising application in w-LEDs.