A novel Mn-activated fluoride red phosphor Cs(NbOF)(OH)HO:Mn 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.1 (18), p.749-757
• Main Authors: Chen, Yingyuan, Liu, Feilong, Zhang, Ziwang, Hong, Junyu, Molokeev, Maxim S, Bobrikov, Ivan A, Shi, Jianxin, Zhou, Jianbang, Wu, Mingmei
• Format: Article
• 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, Mn 4+ -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, Cs 30 (Nb 2 O 2 F 9 ) 9 (OH) 3 H 2 O: x Mn 4+ (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% Mn 4+ -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 K 2 SiF 6 :Mn 4+ 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. Due to the presence of Nb 5+ , a Mn 4+ -doped compound (denoted as CNOFM) shows very good waterproof stability, even without any surface modification. Warm WLEDs with a high color rendering index have been fabricated using the CNOFM red phosphor.