Eu3+-based efficient red phosphors Y1-xEuxGa3(BO3)4 (0

Abstract

The current white light emitting diode (WLED) employs an InGaN chip together with the yellow phosphor Y3Al5O12:Ce3+, however it has a weakness of insufficient red component. In addition to traditional Eu2+ or Mn4+ based red phosphors, we propose that Eu3+ in a noncentrosymmetric coordination could be an alternative for pure red emission and most importantly, it could be efficiently excited by f-f transitions in the near ultraviolet (NUV) region. Complete solid solutions of Y1-xEuxGa3(BO3)4 were prepared by typical solid state reactions, and the crystallographic refinements proved the successful cationic substitutions, where Eu3+ locates at the Y3+ site exclusively. Eu3+ is coordinated by oxygen atoms in a triangular prism symmetry, thus emits a strong and pure red light with the CIE coordinate (0.667, 0.333) upon 393 nm excitation. The internal quantum yields for the samples with x = 0.1, 0.5 and 1 are as high as 81%, 80% and 75%, respectively. In-situ high temperature photoluminescence study confirmed that Y0.1Eu0.9Ga3(BO3)4 retained 84% of the emission intensity at 423 K compared to the value at room temperature, which is sufficiently good for NUV LED applications.