Phosphors

Abstract

Small particles provide for improved performance as phosphors especially in the production of display devices. Particles with a diameter less than about 100 nm have altered band properties that affect the emission by the particles. A collection of such small particles with a narrow distribution around a selected average diameter can be used to produce emission at a desired frequency. These particles are effective for producing a wide variety of display types including flat panel displays. Laser pyrolysis provides an efficient process for the production of desired particles.

1 . A display device comprising phosphor particles having an average diameter less than about 95 nm and wherein the phosphor particles comprise a first collection of particles having a diameter distribution such that at least about 95 percent of the particles have a diameter greater than about 40 percent of the average diameter and less than about 160 percent of the average diameter and the phosphor particles comprising a metal oxide.  
   
   
       2 . The display device of  claim 1  wherein the phosphor particles comprise a metal compound selected from the group consisting of ZnO, TiO 2  and Y 2 O 3 .  
   
   
       3 . The display device of  claim 2  wherein the metal compound is ZnO.  
   
   
       4 . The display device of  claim 1  wherein the phosphor particles have an average diameter from about 5 nm to about 50 nm.  
   
   
       5 . The display device of  claim 1  wherein the phosphor particles have a diameter distribution such that at least about 95 percent of the particles have a diameter greater than about 60 percent of the average diameter and less than about 140 percent of the average diameter.  
   
   
       6 . The display device of  claim 1  wherein the light emission follows low velocity electron excitation.  
   
   
       7 . The display device of  claim 1  wherein the phosphor particles further comprise a second collection of particles, the second collection of particles having a diameter distribution such that at least about 95 percent of the particles have a diameter greater than about 40 percent of the average diameter and less than about 160 percent of the average diameter.  
   
   
       8 . The display device of  claim 1  wherein the phosphor particles are in contact with an anode.  
   
   
       9 . The display device of  claim 1  further comprising a liquid crystal layer.  
   
   
       10 . The display device of  claim 1  further comprising a partially light transparent substrate.  
   
   
       11 . The display device of  claim 1  further comprising a transparent electrode comprising indium tin oxide.  
   
   
       12 . The display device of  claim 1  further comprising an electrode to guide the electrons from the cathode to the anode.  
   
   
       13 . The display device of  claim 1  wherein the display is an electroluminescent display.  
   
   
       14 . The display device of  claim 1  wherein the device is a field emission device with the phosphor particles located between an anode and cathode.  
   
   
       15 . The display device of  claim 14  comprising a plurality of anodes and cathodes where each electrode pair forms an addressable pixel.  
   
   
       16 . The display device of  claim 1  wherein the phosphor particles are roughly spherical.  
   
   
       17 . The display device of  claim 1  wherein the phosphor particles are excitable by low velocity electrons.