Thermally stable white-emitting single composition Na(Sr,Ba)PO_4:Eu~(2+), Mn~(2+) phosphor for near-ultraviolet-pumped light-emitting diodes

摘要

Eu~(2+) and Mn~(2+) codoped, white-emitting Na(Sr, Ba)PO_4 phosphors are prepared, and their emission properties, especially for thermal stability, are thoroughly investigated. The thermal quenching and Eu~(2+)/Mn~(2+) energy transfer efficiency are totally different in the ratio of alkaline earth metals in host composition, NaBaPO_4, Na(Sr_(0.5)Ba_(0.5))PO_4, and NaSrPO_4, respectively. Furthermore, by using near-ultraviolet light-emitting diodes (LEDs) and the corresponding Na(Sr_(0.5)Ba_(0.5))PO_4:Eu~(2+), Mn~(2+) phosphor as light converters, we demonstrate a bright and thermally stable white-emitting LED. The resultant LED exhibits a warm white light [～4900 K, CIE coordinates of (0.33, 0.31)] with excellent thermal and hydrolytic stabilities comparable to those of commercially available ones, Y_3Al_5O_(12):Ce~(3+) and BaMg_2Al_(16)O_(27):Eu~(2+). The proposed composition, with its efficient energy transfer, could enable Eu~(2+) and Mn~(2+) co-doped Na(Sr, Ba)PO_4 to be a promising single component phosphor for cost-effective white-emitting LEDs.