Ce3+-activated BaAlSi5N7O2: A novel cyan-emitting phosphor with superior thermal stability for full-visible-spectrum LED lighting

Traditional commercial white light-emitting diodes (WLEDs) suffer from insufficient cyan light intensity and substandard spectral continuity, which restricts their application in the field of high-end lighting. To improve the performance of WLEDs, there is an urgent need for suitable and bright cyan phosphors. Herein, we report a bright cyan-emitting phosphor BaAlSi 5 N 7 O 2 :Ce 3+ , which exhibits a broadband centered at 479 nm with a full-width at half-maximum (FWHM) of 99 nm. The phosphor also exhibits exceptional thermal stability, retaining 94% of its room-temperature luminescence intensity at 150 °C. When integrated into full-spectrum phosphor-converted WLEDs, BaAlSi 5 N 7 O 2 :Ce 3+ effectively compensates for cyan light deficiency in blue/yellow/red phosphor systems and enhances the color rendering index (Ra) of RGB (red/green/blue)-based WLEDs. Furthermore, BaAlSi 5 N 7 O 2 :Ce 3+ serves as an independent high-efficiency cyan component, replacing conventional blue modules to reduce harmful high-energy blue light exposure. In full-spectrum WLEDs fabricated by combining this phosphor with commercial red/green phosphors on near-ultraviolet (n-UV) LED chips, the device achieves Ra = 94.2, correlated color temperature (CCT) = 4044 K, and minimal high-energy blue light (∼5%). It demonstrates stable chromaticity coordinates and high luminous efficiency under 10–120 mA current, providing a high-performance cyan phosphor solution for healthy lighting.