Ca2PO4Cl : Eu2+: an intense near-ultraviolet converting blue phosphor for white light-emitting diodes

Abstract

A blue phosphor Ca₂PO₄Cl: Eu²⁺ was synthesized by solid state reaction and evaluated as a candidate for white LEDs. The luminescent intensity of Ca₂PO₄Cl: Eu²⁺ was found to be 128% under excitation at 380 nm, 149% under 400 nm, and 247% under 420 nm, as high as that of BaMgAl₁₀O₁₇ : Eu²⁺ . Furthermore, Ca₂PO₄Cl: Eu²⁺ reveals high quantum efficiency and excellent thermal stability. By utilizing a mixture of blue-emitting Ca₂PO₄Cl: Eu²⁺ , green-emitting (Ba,Sr)₂SiO₄ : Eu²⁺ and red-emitting CaAlSiN₃ : Eu²⁺ as light converters, an intense white GaN-based n-UV-LED (400 nm) was fabricated to exhibit an excellent color-rendering index R_a of 93.4 at a correlated color temperature of 4590 K. Based on the results, we are currently evaluating the potential application of Ca₂PO₄Cl: Eu²⁺ as a blue-emitting near-UV convertible phosphor.