자외선 여기용 청색 및 황색 형광체의 발광특성

Abstract

We have synthesized a Eu2+ -activated Sr₃MgSi₂O8 blue phosphor and (Sr,Ba)₂SiO₄ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm, and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the Sr₃MgSi₂O8:Eu blue phosphor and (Sr,Ba)₂SiO₄:Eu yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of Eu2+ impurity ions in the Sr₃MgSi₂O8 and (Sr,Ba)₂SiO₄ host matrix. As a consequence of a preparation of UV White LED lamp using the Sr₃MgSi₂O8:Eu blue phosphor and (Sr,Ba)₂SiO₄:Eu yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x=0.3140, CIE y=0.3201 and CCT (6500 K).