Photoactive Transparent Conductive Films

Abstract

A composite conductive film is provided that includes a layer of photoresist material and an inorganic mesh comprising a plurality of particles of an inorganic material. The plurality of particles of the inorganic mesh is embedded within the layer of photoresist material and the layer of photoresist material and the inorganic mesh are arranged to form the composite conductive film. Furthermore, a method of making a composite conductive film is provided that includes providing, as a matrix, a layer of photoresist material, introducing a plurality of inorganic particles upon a surface of the layer of photoresist material and embedding at least some of the plurality of inorganic particles into the layer of photoresist material to form an inorganic mesh within the layer of photoresist material, thereby forming the composite conductive film.

What is claimed is: 
     
         1 . A composite conductive film, comprising:
 a layer of photoresist material; and   an inorganic mesh comprising a plurality of particles of an inorganic material;   wherein
 the plurality of particles of the inorganic mesh is embedded within the layer of photoresist material; and 
 the layer of photoresist material and the inorganic mesh are arranged to form the composite conductive film, wherein the composite conductive film is substantially transparent to optical light. 
   
     
     
         2 . The composite conductive film of  claim 1 , wherein composite conductive film is characterized by a transparency in that is greater than 50%. 
     
     
         3 . The composite conductive film of  claim 1 , wherein the respective particles of the plurality of particles of the inorganic mesh comprise a conductive material. 
     
     
         4 . The composite conductive film of  claim 3 , wherein the respective particles of the plurality of particles are fused to form a substantially continuous network of the conductive material over a continuous portion of the composite conductive film. 
     
     
         5 . The composite conductive film of  claim 4 , wherein the substantially continuous network of the conductive material is confined to a surface region of the layer of photoresist material, thereby forming a substantially two-dimensional continuous network of the conductive material proximal to a surface of the layer of photoresist material. 
     
     
         6 . The composite conductive film of  claim 5 , wherein the conductive material is a metallic material. 
     
     
         7 . The composite conductive film of  claim 6 , wherein the respective particles of the plurality of particle are metallic particles and the plurality of particles is characterized by a density within the surface region that is above a two-dimensional percolation threshold and less than a bulk percolation threshold of the conductive material suspended throughout the layer of photoresist material. 
     
     
         8 . The composite conductive film of  claim 1 , wherein:
 the surface region has a thickness; and   the composite conductive film is characterized by a first surface roughness that is less than a second surface roughness of a stand-alone film consisting of the same thickness of the inorganic mesh.   
     
     
         9 . The composite conductive film of  claim 8 , wherein the first surface roughness is about fifty percent less than the second surface roughness. 
     
     
         10 . The composite conductive film of  claim 1 , wherein the thickness of the surface region is selected in accordance with a target conductivity value. 
     
     
         11 . The composite conductive film of  claim 1 , wherein the respective particles of the plurality of particles comprise one of nanowires or nanotubes. 
     
     
         12 . The composite conductive film of  claim 1 , wherein the layer of photoresist material comprises a polymer that undergoes cross-linking when exposed to ultraviolet (UV) radiation. 
     
     
         13 . The composite conductive film of  claim 12 , further comprising a plurality of instances of the composite conductive film patterned upon a substrate, each instance of the plurality of instances comprising a region of the composite conductive film, wherein the polymer within each of the regions is substantially cross-linked. 
     
     
         14 . A method of fabricating a transparent composite conductive film, comprising:
 providing, as a matrix, a layer of photoresist material;   introducing a plurality of inorganic particles upon a surface of the layer of photoresist material; and   embedding at least some of the plurality of inorganic particles into the layer of photoresist material to form an inorganic mesh within the layer of photoresist material, thereby forming the composite conductive film,   wherein embedding at least some of the plurality of inorganic particles into the layer of photoresist material results in the composite conductive film that is substantially transparent to optical light.   
     
     
         15 . The method of  claim 14 , further comprising, prior to embedding the inorganic particles into the layer of photoresist material, heating the layer of photoresist material from a first temperature to a second temperature, greater than the first temperature, wherein the layer of photoresist material is softer at the second temperature than at first temperature. 
     
     
         16 . The method of  claim 14 , wherein introducing the plurality of inorganic particles upon the surface of the layer of photoresist material comprises spraying a nanowire suspension onto the surface of the layer of photoresist material. 
     
     
         17 . The method of  claim 14 , wherein introducing the plurality of inorganic particles upon the surface of the layer of photoresist material comprises transferring said plurality of inorganic particles from a stamp in a stamp transfer process. 
     
     
         18 . The method of  claim 17 , wherein embedding the at least some of the plurality of inorganic particles into the layer of photoresist material to form the inorganic mesh within the layer of photoresist material comprises pressing the nanowire suspension into the surface of the layer of photoresist material. 
     
     
         19 . The method of  claim 14 , wherein the photoresist is photosensitive to light having an ultraviolet wavelength or a range of wavelengths in an ultraviolet range of wavelengths. 
     
     
         20 . A touch-sensitive device, comprising:
 a driving panel;   a sensing panel electrically coupled with the driving panel by an electrical characteristic having a value;   a plurality of conductive lines patterned upon a surface of at least one of the driving panel and the sensing panel, each of the plurality of conductive lines comprising:
 a layer of photoresist material; and 
 an inorganic mesh that includes a plurality of particles embedded within the layer of photoresist material; and 
   electronic circuitry to detect, using the plurality of conductive lines, a touch input by sensing a change in the value of the electrical characteristic between the driving panel and the sensing panel;   wherein the layer of photoresist material and the inorganic mesh are arranged to form a composite conductive film that is substantially transparent to optical light.