Jia Yajun, Pan Yuexiao, Li Yiqian, Zhang Lijie, Lian Hongzhou, Lin Jun
Key Laboratory of Carbon Materials of Zhejiang Province, College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, P.R. China.
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P.R. China.
Inorg Chem. 2021 Jan 4;60(1):231-238. doi: 10.1021/acs.inorgchem.0c02876. Epub 2020 Nov 11.
Mn-activated red-emitting fluoride phosphors are essential for white light-emitting diodes (WLEDs) with desirable color rendition index (CRI) because of their unique and efficient luminescence characteristics. Herein, we synthesized a novel Mn-activated dodec-fluoride phosphor KRbGeF:Mn (KRGF:Mn) through a facile ionic exchange method at room temperature. A surface-modified strategy using weak reducing agents such as oxalic acid and citric acid is proposed to improve the moisture-resistance ability of KRGF:Mn phosphor dramatically, and the possible mechanism of surface modification has been investigated. A shell formed on the surface of the KRGF:Mn phosphor reduces the concentration of Mn on the surface, which can prevent the internal KRGF:Mn group hydrolysis by the external moisture and effectively decreased the probability of energy migration to surface defects, thereby increasing both the emission efficiency and the moisture-resistance ability of KRGF:Mn. More interestingly, the KRGF:Mn phosphor is quenched after soaking in water for 72 h but recovered to the initial brightness after soaking in the modifier solutions for 2 min. This work fabricates a new efficient red phosphor KRGF:Mn for application in warm WLEDs and provides insight into the mechanism of the strategy to improve the moisture resistance of the stability of Mn through surface modification.
由于其独特且高效的发光特性，锰激活的红色发光氟化物荧光粉对于具有理想显色指数（CRI）的白光发光二极管（WLED）至关重要。在此，我们通过室温下简便的离子交换法合成了一种新型锰激活的十二氟化物荧光粉KRbGeF:Mn（KRGF:Mn）。提出了一种使用草酸和柠檬酸等弱还原剂的表面改性策略，以显著提高KRGF:Mn荧光粉的防潮能力，并研究了表面改性的可能机制。在KRGF:Mn荧光粉表面形成的壳层降低了表面锰的浓度，这可以防止外部水分使内部KRGF:Mn基团水解，并有效降低能量迁移到表面缺陷的概率，从而提高了KRGF:Mn的发光效率和防潮能力。更有趣的是，KRGF:Mn荧光粉在水中浸泡72小时后会猝灭，但在改性剂溶液中浸泡2分钟后会恢复到初始亮度。这项工作制备了一种用于暖白光发光二极管的新型高效红色荧光粉KRGF:Mn，并深入了解了通过表面改性提高锰稳定性的防潮策略的机制。
