CaScAlSiO₆:Eu²⁺: A novel near-ultraviolet converting blue-emitting phosphor for white light-emitting diodes

A high intense blue-emitting phosphor CaScAlSiO₆:Eu²⁺ (CSAS:Eu²⁺) peaking at 430–460 nm was synthesized by solid state reactions. The luminescence properties of CSAS:Eu²⁺ phosphors as well as thermal quenching and the fabrication of white-light-emitting diodes (W-LEDs) were firstly investigated. The optimal doping concentration of Eu²⁺ is 2 mol% and the critical distance for energy transfer is determined to be 19.49 Å. By utilizing a mixture of blue-emitting CSAS:Eu²⁺, green-emitting SrSi₂O₂N₂:Eu²⁺ and red-emitting CaAlSiN₃:Eu²⁺ phosphors as light converters, an intense white GaN-based n-UV-LED (370 nm) was fabricated to exhibit good color-rendering index R _a of as high as 87.98 at correlated color temperature of 5537 K and CIE coordinates of (0.33, 0.42). Based on the results, we are currently evaluating the potential application of CSAS:Eu²⁺ as a blue-emitting near-UV convertible phosphor.