Zhu Haomiao group and Chen Xueyuan group of Fujian Institute of physical composition, Chinese Academy of sciences have made new progress in the research field of fluoride red fluorescent powder with high moisture resistance for wide color gamut display

White LED is widely used in the field of lighting and LCD because of its advantages of energy saving, environmental protection and long life The backlight of liquid crystal display requires the luminescent materials (blue, green and red) to have the narrowest emission bandwidth and appropriate emission wavelength, so as to obtain high color purity and wide color gamut (> 92% NTSC) However, the current commercial nitride red fluorescent powder is difficult to meet this requirement In recent years, Mn 4 + doped fluoride phosphor has been widely concerned because of its advantages of being effectively excited by blue light, high luminous efficiency and sharp emission lines It has an excellent application prospect in the field of wide color gamut liquid crystal display However, the humidity resistance of this kind of materials is generally poor, which is mainly due to the fact that the Mn4 + ions on the surface of the materials are easy to react with the water in the air, which leads to the deterioration of the materials and affects the life of the LED devices, which also becomes the biggest challenge hindering its commercial application Zhu Haomiao research group and Chen Xueyuan research group of Fujian Institute of material structure, Chinese Academy of Sciences, cleverly used a fast reverse ion exchange method to treat the surface of K 2tif 6: Mn 4 + materials, and successfully prepared K 2tif 6: Mn 4 + @ K 2tif 6 red fluorescent powder with core-shell structure The inert K 2tif 6 shell on the surface of the material can not only improve the moisture resistance by blocking the contact of Mn 4 + ions in the inner layer with water, but also effectively block the channel of excited state energy transferring to the surface lattice defects, so as to improve the luminous efficiency The results show that after the reverse ion exchange treatment, the luminous efficiency of the material (the sample with 7 at.% doping concentration) increases from 75% to 93%; after aging at 85 ℃ / 85% humidity for 480 h, the luminous intensity retention rate of the material increases from 45% to 89%, indicating that the moisture resistance of the material has been greatly improved Under the condition of 60 Ma driving current, the color temperature is 3510 K, the color rendering index RA = 93, and the lumen efficiency is 162 LM · W-1, which is the highest value reported in the literature The reverse ion exchange process developed by the research team is fast and simple, and can be carried out at room temperature and atmospheric pressure, which can improve the luminous efficiency and moisture resistance of the material at the same time, and has a good application prospect The above work was published in angew Chem Int ed (DOI: 10.1002/anie.201813363) and was selected as hot paper The first author of this paper is assistant researcher Huang Decai, and the LED device packaging and testing work is completed by Guo Wang Group of Fujian Institute of physical composition.