Tunable Photoluminescence Properties of Single-Phase Ca8srla(Po4)7:Eu2+,Mn2+ Phosphors for Warm White Leds

Abstract

The phosphor-converted white light-emitting diodes (w-LEDs) have been regarded as a promising alternative to the traditional light source in the fields of lighting. Herein, a series of single-composition emission tunable Ca8SrLa(PO4)7:Eu2+,Mn2+(CSLP:Eu2+,Mn2+) phosphors were synthesized by the high temperature solid-state method. The phase and crystal structures were analyzed. The Eu2+ activated phosphors can be efficiently excited by ultraviolet (UV) light in the range 250–400 nm range and give intense green emission peak at 510 nm. By co-doping Eu2+ and Mn2+ ions into the CSLP host and singly varying the doping content of Mn2+ ions to tune the relative intensities of green and red emission, single-phase phosphors of different colors can be obtained. With increasing the concentration of Mn2+, the phosphor can be tuned from green to warm white. The energy transfer from Eu2+ to Mn2+ in CSLP:Eu2+,Mn2+ was further investigated based on decay lifetime data and photoluminescence, which shows the Eu2+ to Mn2+ ions via a dipole–dipole mechanism. The Commission Internationale deL'Eclairage (CIE) and thermally stable luminescence behaviors of CSLP:Eu2+,Mn2+ phosphor were also studied in detail. All the results indicate that CSLP:Eu2+,Mn2+ phosphors have potential applications as UV-convertible phosphors for w-LEDs.

Keywords: Luminescence, energy transfer, color-tunable, Solid-reaction, w-LEDs