Stabilized fluoride phosphor for light emitting diode (led) applications

Abstract

A stabilized fluoride phosphor for light emitting diode (LED) applications includes a particle comprising manganese-activated potassium fluorosilicate and an inorganic coating on each of the particles. The inorganic coating comprises a silicate. A method of making a stabilized fluoride phosphor comprises forming a reaction mixture that includes particles comprising a manganese-activated potassium fluorosilicate; a reactive silicate precursor; a catalyst; a solvent; and water in an amount no greater than about 10 vol. %. The reaction mixture is agitated to suspend the particles therein. As the reactive silicate precursor undergoes hydrolysis and condensation in the reaction mixture, an inorganic coating comprising a silicate is formed on the particles. Thus, a stabilized fluoride phosphor is formed.

1 . A light emitting device comprising:
 a wavelength conversion material including a stabilized fluoride phosphor comprising:
 particles comprising manganese-activated potassium fluorosilicate; and 
 an inorganic coating on each of the particles, the inorganic coating comprising a silicate; and 
   a blue light emitting diode (LED) chip having a dominant wavelength of 420 nm to 490 nm in optical communication with the wavelength conversion material for down conversion of light emitted from the blue LED chip.   
     
     
         2 . The light emitting device of  claim 1  exhibiting narrow-band red light emission with a peak emission wavelength in a range from 610 nm to 660 nm and comprising a full-width-at-half-maximum (FWHM) of less than 45 nm. 
     
     
         3 . The light emitting device of  claim 1 , wherein the wavelength conversion material further comprises a plurality of quantum dots. 
     
     
         4 . The light emitting device of  claim 1 , wherein the wavelength conversion material further comprises a yellow phosphor exhibiting yellow light emission with a peak emission wavelength in a range from 575 nm to 600 nm. 
     
     
         5 . The light emitting device of  claim 4 , wherein the yellow light emission has a full-width-at-half-maximum (FWHM) of less than 60 nm, the yellow light emission being narrow band yellow light emission. 
     
     
         6 . The light emitting device of  claim 1 , wherein the wavelength conversion material further comprises a green phosphor exhibiting green light emission with a peak emission wavelength in a range from 498 nm to 550 nm. 
     
     
         7 . The light emitting device of  claim 6 , wherein the green light emission has a full-width-at-half-maximum (FWHM) of less than 60 nm, the green light emission being narrow band green light emission. 
     
     
         8 . The light emitting device of  claim 1  used in at least one of the following: indoor lighting products; display backlighting for televisions, monitors, tablets or smart phones; and horticultural lighting products. 
     
     
         9 . The light emitting device of  claim 1 , wherein the stabilized fluoride phosphor further comprises a fluoride coating under the inorganic coating. 
     
     
         10 . The light emitting device of  claim 9 , wherein the fluoride coating comprises potassium fluorosilicate without an activator, or another fluoride compound. 
     
     
         11 . The light emitting device of  claim 1 , wherein the silicate comprises a multicomponent silicate including aluminum, boron, and/or titanium. 
     
     
         13 . The light emitting device of  claim 1 , wherein the silicate comprises SiO x , where 0.5≤x≤2.5. 
     
     
         12 . The light emitting device of  claim 1 , wherein the inorganic coating further comprises an oxide of aluminum, boron, and/or titanium. 
     
     
         14 . The light emitting device of  claim 1 , wherein the inorganic coating comprises a thickness in the range from about 5 nm to about 2 microns. 
     
     
         15 . The light emitting device of  claim 14 , wherein the thickness is in a range from about 0.1 micron to about 2 microns. 
     
     
         16 . The light emitting device of  claim 1 , wherein the inorganic coating further comprises Si—OH groups. 
     
     
         17 . The light emitting device of  claim 1 , wherein the stabilized fluoride phosphor comprises an infrared absorption spectrum wherein a ratio of an absorption intensity of a SiO x , signal to an absorption intensity of a SiF 6   2−  signal is in a range from about 0.05 to about 2.5.