Luminescence and energy transfer of 432 nm blue LED radiation-converting phosphor Ca4Y6O(SiO4)6:Eu2+, Mn2+ for warm white LEDs

Abstract

A series of Ca₄Y₆O(SiO₄)₆:Eu²⁺, Mn²⁺ phosphors are synthesized by a solid state method. Ca₄Y₆O(SiO₄)₆:Eu²⁺, Mn²⁺ can be excited at wavelength ranging from 250 to 500 nm, which is well matched with ultraviolet-visible light emitting diode. Under 432 nm excitation, Ca₄Y₆O(SiO₄)₆:Eu²⁺, Mn²⁺ can create warm white emission by energy transfer from Eu²⁺ to Mn²⁺. A warm white light emitting diode is fabricated by combining a 432 nm blue LED with a single phase warm white emitting phosphor Ca_3.92Y₆O(SiO₄)₆:0.05Eu²⁺, 0.03Mn²⁺, which has CIE chromaticity coordinates (0.336, 0.319), correlated color temperature (CCT) 4326 K and color rendering index (R_a) 86, respectively. The results indicate Ca₄Y₆O(SiO₄)₆:Eu²⁺, Mn²⁺ may serve as potential warm white emitting phosphor for blue LED based white LEDs.