Full-Visible-Spectrum\nWhite LEDs Enabled by a Blue-Light-Excitable\nCyan Phosphor

Efficient blue-light-excitable broadband\ncyan-emitting\nphosphors\nmay yield full-visible-spectrum white light-emitting diodes (WLEDs)\nwith ultrahigh color rendering (Ra > 95). However, this requires\nclosing\nthe “cyan gap” in the 480–520 nm region of the\nvisible spectrum, which is challenging. Herein, a well-performed cyan-emitting\ngarnet phosphor Ca<sub>2</sub>LuAlGa<sub>2</sub>Si<sub>2</sub>O<sub>12</sub>:Ce<sup>3+</sup> (CLAGSO:Ce<sup>3+</sup>) is reported. Under\n430 nm excitation, the optimal CLAGSO:5�<sup>3+</sup> compound exhibits\na broadband cyan emission (peak, 496 nm; bandwidth, 102 nm) with a\nhigh internal quantum efficiency of 85.6% and an excellent thermal\nresistance performance (69.1% at 423 K). Importantly, this as-prepared\ncyan-emitting phosphor provides sufficient cyan emission and enables\nfilling the well-known so-called “cyan gap” between\nthe blue LED chip and the commercial Y<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>:Ce<sup>3</sup><sup>+</sup> (YAG:Ce<sup>3+</sup>) yellow\nphosphor. Impressively, a WLED device fabricated with the optimal\nCLAGSO:5�<sup>3+</sup> sample shows a low correlated color temperature\n(4053 K) and an ultrahigh color rendering index (Ra = 96.6), as well\nas an excellent luminous efficacy (74.09 lm W<sup>–1</sup>).\nThese results highlight the importance of blue-excited broadband cyan-emitting\nphosphors in closing the cyan gap and enabling human-centric full-visible-spectrum\nwarm WLED devices for high-quality solid-state lighting.