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

• Published in: Advanced functional materials 2019-07, Vol.29 (30), p.n/a
• Main Authors: Liao, Hongxu, Zhao, Ming, Zhou, Yayun, Molokeev, Maxim S., Liu, Quanlin, Zhang, Qinyuan, Xia, Zhiguo
• Format: Article
• Language: English
• Subjects: Backlights; Color; Cubes; Diodes; Emission; Emitters; Europium; LCDs; light‐emitting diodes; Liquid crystal displays; Luminous efficacy; Materials science; Optical properties; Organic chemistry; phosphor; Phosphors; photoluminescence; Polyhedra; Quantum efficiency; Thermal stability; Transformations; White light
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201901988

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(Li3SiO4)2:Eu2+ (RN:Eu2+) with exceptional optical properties and excellent thermal stability, is reported. The resulting RN:Eu2+ 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:Eu2+ also shows a high quantum efficiency, an improved chemical stability, and a reduced Stokes shift owing to the modified local environment, in which [NaO8] cubes replace [LiO4] squares in RbLi(Li3SiO4)2:Eu2+ 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:Eu2+ as the green emitter, K2SiF6:Mn4+ 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:Eu2+ for wide‐color‐gamut LCD backlight application. Using a polyhedron transformation methodology, a new and stable narrow‐band green‐emitting phosphor, RbNa(Li3SiO4)2:Eu2+, is successfully developed. The 41‐nm narrow‐band emission, high external quantum efficiency (44.2%), and better chemical stability make it a desirable candidate for liquid crystal display (LCD). By using RbNa(Li3SiO4)2:Eu2+ as the green component of backlights, a wide‐color‐gamut LCD screen is demonstrated.