Touch screen devices employing nanostructure networks

Abstract

Touch screen displays comprising at least one nanostructure-film, and fabrication methods thereof, are discussed. Nanostructure-films may comprise, for example, a network(s) of nanotubes, nanowires, nanoparticles and/or graphene flakes. Such films are preferably at least semi-transparent and relatively flexible, making them well-suited for use in a variety of touch screen applications.

1 . A multilayer device, comprising:
 a first conductive layer; and   a first substrate, wherein the first conductive layer is transparent,   wherein the first substrate is transparent,   wherein the first conductive layer is coated on the first substrate, and   wherein the first conductive layer comprises a first network of nanostructures.   
   
   
       2 . The device of  claim 1 , further comprising:
 a second conductive layer;   a second substrate; and   a spacer layer, wherein the second conductive layer is coated on the second substrate,   wherein the first and second conductive layers face each other and are separated by the spacer layer,   wherein at least one of the first substrate and the second substrate is flexible, and   wherein the spacer layer prevents contact between the first and second conductive layers in the absence of external deformation.   
   
   
       3 . The device of  claim 2 , wherein nanostructures of the first network of nanostructures are substantially single-walled carbon nanotubes. 
   
   
       4 . The device of  claim 3 , wherein the first conductive layer further comprises a conducting polymer. 
   
   
       5 . The device of  claim 4 , wherein at least one of the first and second conductive layers is patterned. 
   
   
       6 . The device of  claim 5 , wherein the second conductive layer comprises a second network of nanostructures. 
   
   
       7 . The device of  claim 1 , wherein the first conductive layer has a sheet resistance of less than 500 ohm/sq and a transmittance of at least 90% for 550 nm wavelength light. 
   
   
       8 . The device of  claim 1 , wherein the first conductive layer has a sheet resistance of less than 350 ohm/sq and a transmittance of at least 90% for 550 nm wavelength light. 
   
   
       9 . The device of  claim 1 , wherein the first conductive layer has a sheet resistance of less than 200 ohm/sq and a transmittance of at least 90% for 550 nm wavelength light. 
   
   
       10 . The device of  claim 1 , further comprising at least two circuits, wherein the first conductive layer stores an electric charge, and
 wherein the circuits detect changes in capacitance across the first conductive layer when the first conductive layer is contacted by an external capacitance field.   
   
   
       11 . A method of fabricating a multi-layer device, comprising:
 depositing a first conductive layer on a first substrate,   depositing a second conductive layer on a second substrate; and   affixing the first substrate to the second substrate such that the first conductive layer faces the second conductive layer,   wherein a spacer layer prevents contact between the first and second conductive layers in the absence of external deformation,   wherein at least one of the first and second substrates is flexible, and   wherein the first conductive layer comprises a first network of nanostructures.   
   
   
       12 . The method of  claim 11 , wherein nanostructures of the first network of nanostructures are substantially single-walled carbon nanotubes. 
   
   
       13 . The method of  claim 12 , further comprising depositing a conducting polymer that substantially fills open porosity in the first conductive layer. 
   
   
       14 . The method of  claim 13 , wherein the second conductive layer comprises a second network of nanostructures, and
 wherein at least one of the first network of nanostructures and the second network of nanostructures is patterned.   
   
   
       15 . The method of  claim 11 , wherein the first conductive layer is deposited by a multi-step spraying and washing process, comprising:
 spraying nanostructures in solution onto the first substrate;   washing the first substrate after spraying; and   repeating the spraying and washing until a nanostructure-film of desired thickness is achieved, wherein the first substrate is heated during the spraying process.   
   
   
       16 . The method of  claim 11 , wherein the first conductive layer is deposited by transfer stamping. 
   
   
       17 . A touch screen comprising a first network of substantially single-walled carbon nanotubes (SWNTs) deposited on a first substrate, wherein both the first network of SWNTs and the first substrate are transparent. 
   
   
       18 . The touch screen of  claim 17 , further comprising a second network of substantially SWNTs deposited on a second substrate, wherein the first and second networks of substantially SWNTs face each other and are separated by a spacer layer,
 wherein the spacer layer prevents contact between the first and second networks of substantially SWNTs in the absence of external deformation, and   wherein at least one of the first and second substrates is flexible.   
   
   
       19 . The touch screen of  claim 18 , wherein at least one of the first and second networks of substantially SWNTs has a sheet resistance of less than 500 ohm/sq and a transmittance of at least 90% for 550 nm wavelength light. 
   
   
       20 . The touch screen of  claim 18 , wherein at least one of the first and second networks of substantially SWNTs has a conductivity of at least 1000 S/cm.