Ba3Y2B6O15:Ce3+—A High Symmetry, Narrow-Emitting Blue Phosphor for Wide-Gamut White Lighting

The production of white light based on a near-UV LED chip requires incorporating three inorganic phosphors that emit in the blue, green, and red portions of the visible spectrum. Using a near-UV LED has the advantage of generating a light with excellent color quality, but due to the large Stokes' shift between the LED excitation and the multiple phosphor emissions, these devices can suffer from a low overall efficiency. To minimize this inherent energy loss, the three phosphors employed to convert the LED emission must be very efficient, as measured by the internal photoluminescent quantum yield (Φ). In this work, we report the synthesis of a cubic borate, Ba3Y2B6O15, which when substituted with Ce3+ becomes an efficient blue phosphor. This compound can be prepared using a multistep high temperature solid state synthesis with the ensuing photoluminescent measurements revealing a broad excitation band (300–415 nm) making this phosphor compatible with a 365 or 400 nm LED chip. Ba3Y2B6O15:Ce3+ luminesces bright blue (λem = 446 nm) and is the narrowest Ce3+ based phosphor reported thus far with a full width at half the maximum of only 70 nm due to its highly symmetric, nearly perfect octahedral rare-earth coordination environment. Moreover, exciting Ba3Y2B6O15:Ce3+ at 365 nm results in a Φ of 84% owing to the dense connectivity of the crystal structure. This combination of a broad excitation spectrum, narrow emission, and high Φ suggest that Ba3Y2B6O15:Ce3+ is an excellent phosphor for incorporation in a three-phosphor, near-UV LED system. Furthermore, these results demonstrate that a highly symmetric and ordered rare-earth environment in combination with a highly connected polyhedral network is a universal design criterion to generate narrow-emitting phosphors.