Synthesis and luminescent properties of novel cyan-green-emitting phosphors Na3YSi2O7: Eu2+ for full-spectrum lighting

The discovery of novel high-efficiency cyan-green-emitting phosphors is great meaningful for the achievement of full-spectrum white LED, but still a challenge due to the strict crystal field limitation. Herein, we present a novel cyan-green-emitting phosphor Na₃YSi₂O₇:Eu²⁺ synthesized by high-temperature solid-state reaction. The crystal structure, photoluminescence (PL) properties, PL spectra at low temperature, decay lifetime and thermal stability of these phosphors are investigated on detailed. The Eu²⁺ ions occupy the Na(2)⁺ crystallographic sites and Y³⁺ sites. The emission spectra of those phosphors consist of a cyan-green emission bands around 475-650 nm with a full width at half maximum (FWHM) of 71 nm upon the excitation at 365 nm. Two different Eu²⁺ cyan-green-emitting centers are identified by the PL spectra. The interesting red emission of Eu²⁺ ions in Na₃YSi₂O₇: Eu²⁺ phosphor at 665 nm is observed at 8 K and disappeared at room temperature. The concentration quenching mechanism of Eu²⁺ in Na₃YSi₂O₇ is determined. The fluorescence lifetimes of the as-prepared Na₃YSi₂O₇: xEu²⁺ (x = 0.005–0.025) samples are several hundred nanoseconds and the temperature-dependent luminescence indicated Na₃YSi₂O₇: Eu²⁺ is poor thermal-stable. High-quality neutral-white light (CRI = 89, CCT = 4049 K) were emitted from the LED fabricated by this cyan-green Na₃YSi₂O₇: Eu², commercial red phosphors and 365 nm violet chips. Our results indicate that novel cyan-green-emitting Na₃YSi₂O₇: Eu²⁺ phosphors are expected to have potential application in the field of full-spectrum white LED.