High luminescent thermal stability and water resistance of K2SiF6:Mn4+@CaF2 red emitting phosphor. Issue 23 (1st December 2021)

• Record Type: Journal Article
• Authors: Yu, Yan; Wang, Tianman; Zhong, Xue; Li, Yuelan; Wang, Lin; Liao, Sen; Huang, Yingheng; Long, Jinqiao
• Is Part Of: Ceramics international. Volume 47:Issue 23(2021)
• Page Start: 33172
• Page End: 33179
• Publication Date: 2021-12-01
• Subjects: Mn4+-doped fluoride -- WLEDs -- Red-emitting phosphor -- Moisture resistance -- Surface modification; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.08.218
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: K2 SiF6 :Mn 4+ (KSF:Mn 4+ ), as an efficient red-emitting phosphor, has a promising application in WLEDs (white light-emitting diodes). However, poor moisture resistance performance still hinders its deeper commercialization. Here, KSF:Mn 4+ @ CaF2 with high water resistance and luminescent thermal stability has been prepared though H2 O2 -free hydrothermal method and surface coating process. Both KSF:Mn 4+ and KSF:Mn 4+ @CaF2 all have high luminescent thermal stability, due to negative thermal quenching (NTQ) effect. Mechanism of the NTQ has been discussed and suggested as thermal-light energy conversion mechanism. Compared with KSF:Mn 4+, water resistance of KSF:Mn 4+ @CaF2 is greatly improved by coating of CaF2, because the outer shell of CaF2 can effectively prevent the [MnF6 ] 2- group on the surface of the phosphor from being hydrolyzed into MnO2 . The results of water resistance test shows that after immersing in water for 360 min (6 h), luminescent intensity of the uncoated product drops to 41.68% of the initial one, while that of the coated product remains to have 88.24% of its initial one. Warm white light with good luminescent performances ( CCT = 3956 K and Ra = 89.3) is got from prototype WLEDs assembled by using the optimal coated sample. The results suggest that the optimal coated sample has potential application in blue-based warm WLEDs.