Preparation,Surface Modification And Its Application In White LED Of K₂SiF₆:Mn⁴⁺ Phosphor

Mn⁴⁺-doped fluoride red phosphors are receiving more and more attention in warm white LED(WLEDs)and liquid crystal display(LCD)background light sources due to their unique and efficient narrow-band red emission and broadband blue-light absorption characteristics.In this paper,K₂SiF₆:Mn⁴⁺phosphor was synthesized in the solution without hydrofluoric acid,and the as-prepared phosphor was also modified to be possessed good chemical stability.The prepared phosphor was packaged in LED device to explores the possibility of its application in white LED,which made up for the lack of red component.The research content of this paper is as follows:(1)K₂SiF₆:Mn⁴⁺red phosphor was prepared with hydrothermal free HF method,(C₂H₅)₄NF was add to the raw material to improve original preparation method.The optimum ratio of(C₂H₅)₄NF doping was explored.When the mole ratio of(C₂H₅)₄NF to KHF₂was 1:15,the emission intensity of the sample reached the maximum,and the luminous intensity was 2.3 times of that which is not been added(C₂H₅)₄NF.The phosphor is single pure phase with good crystallinity.The obtained phosphor is modified to improve its chemical stability.The modified KSFM was applied in LED devices,obtaining the photoelectric parameters of correlated color temperature(CCT)4935 K,color rendering index(CRI)81.3,and chromaticity coordinates(0.35,0.3849).These results indicate that the phosphor has potential applications in white LEDs.(2)The fluoride phosphor K₂SiF₆:Mn⁴⁺was prepared at with homoeothermy free HF method using different silicon sources.The sample had an average particle size of 0.75 to4.9?m.Using TEOS as silicon source,the K₂SiF₆:Mn⁴⁺phosphor can also be prepared and the particle size can reach nanometer scale.When the temperature reached 423 K,the luminescence intensity of K₂SiF₆:Mn⁴⁺phosphor can be maintained above 90%of that at room temperature,which was superior to the commercial Sr/Ca Al Si N₃:Eu²⁺phosphor,indicating that the prepared phosphor had excellent thermal stability.The obtained phosphor was further modified with ODTMS.The photoelectric parameters of the WLED prepared by coated KSFM phosphor were correlated color temperature(CCT)3334 K,color rendering index(CRI)88.91,and chromaticity coordinates(0.4176,0.402).These results exhibit that the phosphor can meet the requirements of warm white LEDs.