A novel Mn4+-activated fluoride red phosphor Cs30(Nb2O2F9)9(OH)3·H2O:Mn4+ with good waterproof stability for WLEDs

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2022-05, Vol.10 (18), p.7049-7057
• Main Authors: Chen, Yingyuan, Liu, Feilong, Zhang, Ziwang, Hong, Junyu, Molokeev, Maxim S, Bobrikov, Ivan A, Shi, Jianxin, Zhou, Jianbang, Wu, Mingmei
• Format: Article
• Language: English
• Subjects: Ambient temperature; Crystal structure; Fluorides; Light emitting diodes; Optical properties; Phosphors; Thermodynamic properties; Water resistance; Water stability; White light
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d2tc00132b

Red-light-emitting materials, as pivotal components of warm white light-emitting diodes (WLEDs), have drawn increasing public focus. Among these, Mn4+-doped red light-emitting fluorides have drawn considerable attention when combined with an InGaN chip; however, they suffer from poor water stability under humid conditions. In this work, a novel fluoride red phosphor, Cs30(Nb2O2F9)9(OH)3·H2O:xMn4+ (CNOFM), with good water resistance was synthesized for the first time using a facile co-precipitation method at ambient temperature. Experiments were implemented for the precise analysis of its crystal structure, optical properties, micro-morphology, thermal behavior, and waterproof properties. 6.66% Mn4+-doped CNOFM maintained a stable crystal structure and possessed strong PL intensity located at 633 nm with high color purity of 96%. CNOFM showed better thermal and waterproof stability compared with the commercial K2SiF6:Mn4+ red phosphor. Without any surface modifications, the PL intensity remained at about 83% of the initial value after immersion in water for 60 min, and the mechanism was investigated. Finally, a warm WLED with a CRI of 92.3 and CCT of 3271 K was fabricated using the CNOFM red phosphor.