Synthesis, structure and photoluminescence properties of a novel color-tunable Si1.92Al0.08O1.08N1.92:Eu2+,Tb3+,Sm2+phosphor for ultraviolet white light-emitting diodes

Abstract

A novel oxynitride phosphor Si_1.92Al_0.08O_1.08N_1.92:x%Eu²⁺,y%Tb³⁺,z%Sm²⁺ (o-sialon) was successfully synthesized through a high temperature solid-state reaction. The crystal structure, photoluminescence properties and thermal quenching properties have been measured and analyzed. The results indicate that the emission colors can be tuned from blue (0.1716, 0.1508) to green (0.3607, 0.5631) by changing the Eu²⁺/Tb³⁺ ratio and tuned from white (0.2377, 0.2991) to deep red (0.3573, 0.2231) by changing the Sm²⁺ concentration from 0 to 0.03% in Si_1.92Al_0.08O_1.08N_1.92:0.18%Eu²⁺,1%Tb³⁺,z%Sm²⁺. The energy transfer from Eu²⁺ to Tb³⁺ in Si_1.92Al_0.08O_1.08N_1.92:Eu²⁺,Tb³⁺ and the energy transfer from Eu²⁺/Tb³⁺ to Sm²⁺ in Si_1.92Al_0.08O_1.08N_1.92:Eu²⁺,Tb³⁺,Sm²⁺ have been studied. The energy transfer mechanism of Eu²⁺ to Tb³⁺ is demonstrated to be a dipole–dipole interaction. Their integrated emission intensities at 150 °C all remain at 90% of that measured at room temperature. The results indicate that the Si_2−nAl_nO_1+nN_2−n:x%Eu²⁺,y%Tb³⁺,z%Sm²⁺ phosphor is a very promising candidate for use as an ultraviolet white light-emitting diode phosphor.