A single Eu2+ activated high color rendering oxychloride white light phosphor for white light emitting diodes
Single phased, high color rendering index (CRI) white light phosphors are emerging as potential phosphor converted white light emitting diodes (WLEDs) and as an alternative to blends of tricolor phosphors. However, it is a challenge to create a high CRI white light from a single doped activator. Here, we present a high CRI (Ra 91) white light phosphor, Sr5(PO4)3 x(BO3)xCl:Eu2+ composed of Sr5(PO4)3Cl as the beginning member and Sr5(BO3)3Cl as the end member. This work utilized the solid solution method, and tunable Eu2+ emission was achieved. Color tunable Eu2+ emissions in response to structural variation were observed in Sr5(PO4)3 x(BO3)xCl solid solutions. This was further confirmed using X ray Rietveld refinement, electron paramagnetic resonance spectroscopy, and in the photoluminescence spectra. The color tunable emissions included the white light that originated from the combination of the blue emission of Sr5(PO4)3Cl:Eu2+ and an induced Eu2+ yellow emission at approximately 550 nm in the solid solution. Importantly, the white light phosphors showed a greater R9 90.2 under excitation at 365 nm. This result has rarely been reported in the literature and is greater than that of (R9 14.3) commercial Y3Al5O12:Ce3+ based WLEDs. These findings demonstrate the great potential of Sr5(PO4)3 x(BO3)xCl:0.04Eu2+ as a white light phosphor for near UV phosphor converted WLEDs. These results also provide a shortcut for developing a high CRI white light phosphor from a single Eu2+ doped compound.
Light, science applications