Synthesis, structure and photoluminescence properties of (Sr,Ca)AlSiN₃:Eu²⁺ phosphor for white light emitting diodes with controllable optical performance

Abstract

A series of Sr_yCa_1−x−yAlSiN₃:xEu²⁺ (x = 0–0.01, y = 0–0.8) phosphors have been successfully prepared by solid state reaction under atmospheric pressure. All the phosphors exhibit orthorhombic crystal structure similar with CaAlSiN₃ structure. It is found that the emission bands for all Ca_1−xAlSiN₃:xEu²⁺ phosphors are centered at ~650 nm and fluorescence quenching has been observed along with the increase of Eu²⁺ concentration in host materials. Through substitution of Ca²⁺ by Sr²⁺, an expected red emission peak (625 nm) and enhanced luminescent intensity can be achieved. The obtained Sr_0.8Ca_0.192AlSiN₃:0.008Eu²⁺ phosphor was further used as efficient red component to fabricate white light emitting diodes (LEDs). Under the optimized condition of LED packaging, the white LEDs own the excellent optical properties with luminous efficiency of 90.6 lm/W and an ideal color rendering index (Ra = 82). Furthermore, the color correlated temperature of white LEDs can be simply adjusted through changing the red phosphor concentration and dispensing package saves time.