Garnet-type cyan-green-emitting SrLu2Ga1.5Al2.5SiO12:Ce3+ phosphor with high quantum efficiency, thermal stability, and water resistance for blue-excited WLEDs

Abstract

Nowadays, high-quality phosphor-converted white light-emitting diodes (pc-WLEDs) ought to include cyan-emitting phosphors allowing for full-spectrum light similar to sunlight. Herein, we report a garnet-structured Ce3+-doped SrLu2Ga1.5Al2.5SiO12 (SLGASO) phosphor that significantly compensates for the absence of cyan light, known as the “cyan cavity”. The SLGASO host crystallizes into a cubic structure with the space group. The cell parameters were determined using Rietveld refinement. Under 430 nm blue excitation, SLGASO:Ce3+ emits intense cyan-green light in the 450‒700 nm wavelength range. The representative SLGASO:0.07Ce3+ phosphor has an internal quantum efficiency (IQE) of 95.4% and excellent thermal stability, remaining 92.7% of its initial emission intensity at 152 °C. After 155 d of immersion in water, the luminous intensity of SLGASO:0.07Ce3+ remains constant, confirming its waterproofness. Furthermore, a pc-WLED device with luminous efficiency (LE) of 101.58 lm/W, color rendering index (Ra) of 91, correlated color temperature (CCT) of 4536 K, and Commission Internationale de L’Eclairage (CIE) chromaticity coordinates of (0.3555, 0.3390) was fabricated by combining as-prepared cyan-green-emitting SLGASO:0.07Ce3+, yellow-emitting Y3Al5O12:Ce3+ (YAG:Ce3+), and red-emitting (Ca,Sr)AlSiN3:Eu2+ phosphors, as well as a 450 nm blue chip. These findings indicate that SLGASO:0.07Ce3+ phosphor can bridge the cyan gap and improve the performance of as-fabricated full-visible-spectrum WLEDs.