A high quantum efficiency CaAlSiN3:Eu2+ phosphor-in-glass with excellent optical performance for white light-emitting diodes and blue laser diodes

Abstract

CaAlSiN3:0.2%Eu2+ (CASN:Eu2+), an excellent red phosphor, playsaleadingpart in wide color gamut and high color rendition white light-emitting diodes (wLEDs). However, this phosphor or silicone resin mixture possesses a fatal defect of an intrinsic low thermal performance, which makes it hardly useful in high-power laser lighting and displays. Here, to improve the thermal performance of the CASN:Eu2+ phosphor, a series of red-emitting phosphor-in-glass materials (R-PiGs) with different CASN:Eu2+ concentrations (5–50 wt%) and sintering temperatures (750–850 °C) were successfully synthesized by dispersing the CASN:Eu2+ phosphor into a B2O3-Na2O-SiO2-CaO glass matrix. Surprisingly, the prepared R-PiGs showed a high external quantum efficiency (EQE) of 53%, and still maintained 82% efficiency compared with the CASN:Eu2+ phosphor (65%). The R-PiGs are superior to red ceramics for low cost and rapid batch preparation. Considering the densification of the R-PiGs, a systematic study was conducted on 10 wt% R-PiG sample. A facile chromaticity tuning for the configured wLEDs was obtained within the color range change from cool white to warm white when using the R-PiGs with different CASN:Eu2+ concentrations. Besides, we have successfully assembled a warm wLED with high luminous efficacy (90.3 lm/W) and color rendering (Ra = 94.2 and CCT = 5053 K). When irradiated by a blue laser, an optimized R-PiG can show enhanced luminous flux (49.27 lm) at a high laser incident power of 1.90 W/mm2. Therefore, with their excellent performances, R-PiGs are highly promising for use as red color converters for potential applications in tunable wLEDs and high-power laser lighting.