Ultraviolet light block and photocatalytic materials

Abstract

Nanoscale UV absorbing particles are described that have high UV absorption cross sections while being effectively transparent to visible light. These particles can be used to shield individuals from harmful ultraviolet radiation. These particles can also be used in industrial processing especially to produce solid state electronic devices by creating edges of photoresist material with a high aspect ratio. The UV absorbing particles can also be used as photocatalysts that become strong oxidizing agents upon exposure to LV light. Laser pyrolysis provides an efficient method for the production of suitable particles.

1 . A method of producing a UV absorbing layer, the method comprising applying a layer of particles to a substantially transparent substrate, the particles comprising metal oxide and having an average particle diameter from about 5 nm to about 100 nm, wherein the particles have 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.  
     
     
         2 . The method of  claim 1  wherein the applying of the layer of particles comprises coating with a particle dispersion.  
     
     
         3 . The method of  claim 1  wherein the applying of the layer of particles comprises directly depositing particles from a stream of particles.  
     
     
         4 . The method of  claim 1  wherein the applying of the layer of particles comprises spray coating.  
     
     
         5 . The method of  claim 1  wherein the applying of the layer of particles comprises spin coating.  
     
     
         6 . The method of  claim 1  wherein the substrate comprises a silicon-based glass.  
     
     
         7 . The method of  claim 1  wherein the substrate comprises an organic polymer.  
     
     
         8 . The method of  claim 1  wherein the metal oxide comprises TiO 2 .  
     
     
         9 . The method of  claim 1  wherein the metal oxide comprises ZnO or ZnO 2 .  
     
     
         10 . The method of  claim 1  wherein the metal oxide comprises CeO 2 .  
     
     
         11 . The method of  claim 1  wherein the 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.  
     
     
         12 . A method of forming a transparent material with reduced UV transmission comprising forming the material with particles dispersed within the material, the particles comprising metal oxide and having an average particle diameter from about 5 nm to about 100 nm.  
     
     
         13 . The method of  claim 12  wherein the transparent material comprises a silicon-based glass.  
     
     
         14 . The method of  claim 12  wherein the transparent material comprises an organic polymer.  
     
     
         15 . The method of  claim 12  wherein the transparent material comprises high density polyethylene or polyester.  
     
     
         16 . The method of  claim 12  wherein metal oxide comprises TiO 2 .  
     
     
         17 . The method of  claim 12  wherein the particles have 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.  
     
     
         18 . A method for forming a photoresist material, the method comprising mixing particles within a UV-sensitive polymer material, the particles comprising metal oxide and having an average particle diameter from about 5 nm to about 500 nm.  
     
     
         19 . The method of  claim 18  wherein the particles comprise TiO 2 , ZnO, ZnO 2  or CeO 2 .  
     
     
         20 . The method of  claim 18  wherein the particles have 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.  
     
     
         21 . The method of  claim 18  wherein the particles have an average particle diameter from about 5 nm to about 150 nm.  
     
     
         22 . The method of  claim 18  wherein the particles have an average particle diameter from about 5 nm to about 100 nm.