Enhanced novel white emission in Ca3(PO4)2:Dy3+ single-phase full-color phosphor by charge compensation

Abstract

A novel single-composition white-emitting phosphor Ca3(PO4)2:Dy3+ has been synthesized by a high-temperature solid-state reaction. The effect of charge compensators on luminescent properties of Ca3(PO4)2:Dy3+ is systematically investigated by the X-ray powder diffraction, UV–Vis diffuse reflectivity, photoluminescence (PL) properties and lifetime. It is observed that the PL intensity of Dy3+ under 350 nm excitation increases in the order of Ca2.95(PO4)2:0.05Dy3+, Ca2.90K0.05(PO4)2:0.05Dy3+, Ca2.90Na0.05(PO4)2:0.05Dy3+, Ca2.90Li0.05(PO4)2:0.05Dy3+, and Ca2.95(P0.95Si0.05O4)2:0.05Dy3+. The lifetimes of Dy3+ are 605.00, 604.67, 615.01, 645.64 and 621.26 μs, respectively. A charge compensation model is proposed to explain the changes in the emission intensity and lifetime of Dy3+ in Ca3(PO4)2 with different compensation methods. A white light-emitting diode (LED) was fabricated by using the white-emitting single-composition Ca2.95(P0.95Si0.05O4)2:0.05Dy3+ pumped by a 365 nm UV-chip. Our results indicated that the CIE chromaticity coordinates, color rendering index and correlated color temperature for white UV-LEDs were (0.302, 0.324), 83, and 6947 K, respectively. Therefore, our novel white Ca2.95(P0.95Si0.05O4)2:0.05Dy3+ can serve as a key material for phosphor-converted white-light UV-LEDs.