Polyhedron Transformation toward Stable Narrow‐Band Green Phosphors for Wide‐Color‐Gamut Liquid Crystal Display

A robust and stable narrow‐band green emitter is recognized as a key enabler for wide‐color‐gamut liquid crystal display (LCD) backlights. Herein, an emerging rare earth silicate phosphor, RbNa(Li 3 SiO 4 ) 2 :Eu 2+ (RN:Eu 2+ ) with exceptional optical properties and excellent thermal stability, is reported. The resulting RN:Eu 2+ phosphor presents a narrow green emission band centered at 523 nm with a full width at half maximum of 41 nm and excellent thermal stability (102%@425 K of the integrated emission intensity at 300 K). RN:Eu 2+ also shows a high quantum efficiency, an improved chemical stability, and a reduced Stokes shift owing to the modified local environment, in which [NaO 8 ] cubes replace [LiO 4 ] squares in RbLi(Li 3 SiO 4 ) 2 :Eu 2+ via polyhedron transformation. White light‐emitting diode (wLED) devices with a wide color gamut (113% National Television System Committee (NTSC)) and high luminous efficacy (111.08 lm W −1 ) are obtained by combining RN:Eu 2+ as the green emitter, K 2 SiF 6 :Mn 4+ as the red emitter, and blue‐emitting InGaN chips. Using these wLEDs as backlights, a prototype 20.5 in. LCD screen is fabricated, demonstrating the bright future of stable RN:Eu 2+ for wide‐color‐gamut LCD backlight application.