Comparative investigation on synthesis and luminescence of Sr4Al14O25:Eu2+ applied in InGaN LEDs

Blue–green-emitting phosphor Sr4Al14O25:Eu2+ was synthesized with three methods: solid-state reaction (SS), co-precipitation method (CP) and sol–gel method (SG). Bright blue–green-emitting LEDs were fabricated by combining the phosphors with InGaN-based near-ultraviolet (NUV) chips, respectively. The effects of preparation processes on the crystallization, morphology, particle size and photoluminescence, especially on the luminescence properties of phosphor-converted light-emitting diodes (PC-LEDs), were investigated. The results reveal that the relatively regular morphology, small particle size and narrow size distribution are favorable for phosphors to absorb the NUV light from the chip and thus reduce the difference in emission intensity of the three phosphors in LEDs.