Patent Application: US-200913262834-A

Abstract:
the presently disclosed subject matter can include or consist of the creation and manufacture of electrochromic thin film transistors , either self - sustaining or not , with lateral or vertical structure , deposited on any kind of functionalized substrate , referred to as electrochromic substrate , or non - functionalized substrate . the electrolyte material and the presence or not of an ultra - thin membrane can act as dielectric element . the electrochromic material can act as active semiconductor of the channel region . the gate , source and drain electrodes can be based on metal materials , such as titanium , gold , aluminum , or degenerate semiconductive oxides , like indium and zinc oxide , gallium - doped zinc oxide . the device operation control process can be made by means of electronic and ionic current , and the off - state to on - state switch , or vice - versa , can be followed by a change of color of the device .

Description:
as previously mentioned , the presently disclosed subject matter relates to the creation and manufacture process of thin film transistor - based electrochromic devices wherein the channel region changes its colour when the transistor switches from the off - state to the on - state ( see fig1 to 3 ). the device is comprised by a substrate ( 1 ) which is either non - functionalized ( fig1 ) or functionalized ( fig2 ), with lateral or vertical structure ( fig3 ). in case the stiff or flexible substrate is a non - functionalized one , onto it a gate electrode ( 4 ) is deposited , followed by the deposition of an electrolyte ( 3 ) containing the marker element that will react with the electrochromic material ( 2 ) that is deposited onto the latter , thereby leading to the observed change of colour , in the juxtaposed or layered form , accelerated by the current that flows between the drain and the source , which is a function of the device operating mode , namely cross - sectional colouring variation or longitudinal colouring variation . in the far ends of the device ( see fig3 ) the drain and source electrodes ( 5 ) are positioned ; when connected to a battery they allow accelerating , together with the gate control voltage , the diffusion of the li + ions from the electrolyte salt into the electrochromic material . the diffusion of the lithium ions depends on the structure , stoichiometry , and morphology of the electrochromic material [ 5 , 6 , 15 ]. the coloured front is initiated close to the anode ( terminal connected to a positive potential ), and the higher the applied voltage the faster is the progression thereof . when the stiff or flexible substrate is a functionalized one , the bulk thereof contains electrochromic material on one side and electrolyte material on the other side ( see fig2 ). the functionalization can be made using chemical solutions that contain nanoparticles , which we shall refer to as functionalized electrochromic inks , plus a salt that contains ions , such as lithium , from which the substrate is provided with characteristics simultaneously of an electrochromic material and an electrolyte by means of a technology such as ink - jet printing , or deep coating , or atomization , or sol - gel , or other , without the need to use a counter - electrode to manufacture electrochromic devices . as previously mentioned , the presently disclosed subject matter relates to a manufacture method that allows creating within the substrate additive and simultaneous functions of electrochromic material and electrolyte and charge storage device , providing the substrate with functionalities of solid state self - sustaining electrochromic device or system , whose functions were unknown before the presently disclosed subject matter . according to what was previously mentioned , the functionalization of the substrate with electrochromic material and electrolyte is conducted by dipping it in a chemical solution that contains nanoparticles of an inorganic oxide and a salt by means of a known technique , such as , for example , deep coating or ink - jet printing , which is a function of the hydrophilic or hydrophobic characteristics of the used substrate , or inserting them in the final stage of the substrate manufacture by means of conformation or other similar technique . according to the description of the previous products , the nanoparticles to be used in the ink solutions or to be inserted as precursors in the manufacturing stage of the substrate can have an inorganic , or organic , or mixed nature . in the case of inorganic nanoparticles , these will be made of oxides of ti , nb , mo , ta , and w to afford a cathodic colouring , or oxides of cr , mn , fe , co , ni , rh , and ir to afford an anodic colouring . according to what was previously described , the organic nanoparticles will be made of vialogens and polymeric materials , such as polyaniline . according to what was previously described , the electrolytic and charge storage functions are due to a lithium - containing inorganic salt , such as li 3 n , lialf 4 , linbo 3 , or polymeric salt of liclo 4 , lii , libr , liasf 6 , and licf 3 so 3 , which is inserted into the substrate by dipping the latter in a chemical solution , as is the case of paper , or the salt is inserted into the bulk of the substrate , during the final stage of the substrate manufacture . according to what was previously described , when the different particles that constitute the electrolyte and electrochromic materials are not inserted during the substrate manufacture process , after dipping the substrate , such as , for example , paper , in the different solutions one should then proceed to the drying thereof in order to remove the solvent , and finally the two transparent electrodes ( tco ) are deposited on both sides of the paper sheet or at the far ends of the region of the paper surface prepared for the connection of the electrical contacts . the electrodes are connected to an external power source , by means of which the potential difference is applied to the device . when applying this potential difference , the ions from the salt will migrate into the electrochromic material . the colouring appears alternately on either side of the substrate depending on the direction of application of the potential difference , always colouring the face where the negative terminal lies . by interchanging the source polarization , the ions will migrate through the cellulosic matrix into the other side of the substrate , and now that side becomes coloured and the opposite side becomes transparent . in this way , the cellulosic substrate soaked up in the previously described solution presents simultaneously 4 different functions according to the conventional electrochromic cells , which are : substrate ( 1 ), electrochromic material ( 2 ), electrolyte ( 3 ), and counter - electrode . according to what was previously described , the device might contain three transparent conductive electrodes ( gate , source , and drain ) that allow applying or inducing the electric field and electric charges , respectively . presently , neither any known patent nor the state of the art comprises the presently disclosed subject matter . the search done in several databases of patent records showed that none of the processes , products , and operating systems of the substrate that are an aspect of the presently disclosed subject matter is described in the state of the art . for processing an electrochromic device as previously described it is possible to use different electrochromic materials as well as salts , but as an example we mention the case of a device developed from a paper substrate with a solution of nanoparticles of tungsten trioxide ( wo 3 ) and lithium perchlorate ( liclo 4 ). it is not necessary to perform on the substrate any kind of pre - treatment or cleaning procedure . it is only required to provide a porous substrate with the desired dimensions . the solution of nanoparticles of wo 3 is prepared from hydrogen peroxide ( h 2 o 2 ) and metallic tungsten ( w ). w is added to h 2 o 2 , the mixture is allowed to rest until a clear solution is obtained , and then the solution is heated until a yellow powder is formed . at this stage acetic acid is added . the heating of the solution is continued until total evaporation of the solvent occurs . the resultant yellow powder is dispersed in anhydrous ethanol . this dispersion is allowed to rest for several days . thereafter lithium perchlorate is added . the substrate is completely immersed in the previously described solution for 1 to 5 minutes . thereafter the substrate is dried in a heater plate at a temperature of 50 to 100 ° c . for 45 to 75 seconds . the gate , drain , and source electrodes are deposited on both sides of the previously described substrate using a mechanical mask , or writing them down by ink - jet techniques , or otherwise using the known lithographic techniques and transparent materials in the visible region , such as , for example , izo ( zinc - doped indium oxide ); gzo ( gallium - doped zinc oxide ); multicomponent oxide of zinc , gallium , and indium , or zinc , gallium , or tin , or alike , having the electrical properties of a degenerate semiconductor , by means of one of the previously mentioned techniques , such as , for example , the sputtering technique at room temperature . in what follows a manufacture example is presented using a vitroceramic substrate and some of the materials that can be used for the creation and manufacture of the thin film transistor . initially it is immersed in isopropyl alcohol at temperatures ranging between 30 ° c . and 50 ° c ., wherein the temperature of 50 ° c . is chosen for this particular example , in an ultra - sound bath for a period of 15 minutes . after this time period , the substrate is withdrawn from the alcohol and is immersed in ultra - pure water at temperatures ranging between 40 ° c . and 65 ° c . 50 for a period equal to the previous one . thereafter , the substrate is dried with a nitrogen jet . using the magnetron - assisted sputtering technique at temperatures ranging between the room temperature and 450 ° c ., the degenerate semiconductive oxide with high conductivity , possibly having an amorphous structure , is deposited according to a pattern that might involve a mechanical mask or lithographic processes , such as lift - off . thereafter it is subjected to a cleaning procedure in order to prepare the thus coated surface to the second manufacture stage . using the same magnetron - assisted sputtering technique or ink - jet printing , one proceeds to the deposition of an insulating material , like amorphous multicomponent compounds of tantalum and silicon , or tantalum and aluminium , or tantalum and hafnium , or polymeric compounds , such as , for example , polymethyl methacrylate pmma , according to a pattern associated with a ( mechanical or photoresist ) mask or by direct writing . in this way the electrical insulation of the gate electrode from the layers that follow , namely the electrolyte and electrochromic materials , is ensured . a material highly sensitive to the charge accumulation process , such as , for example , previously dried lithium perchlorate ( liclo 4 ), is dissolved in propylene carbonate ( pc ), solution m , inside a controlled atmosphere glove box . in parallel , the organic material that will work as electrolyte material , such as , for example , polymethyl methacrylate ( pmma ), is dissolved in ethyl acetate in a ratio ranging from 1 : 5 to 1 : 10 . finally , the previous solution is mixed with liclo 4 + pc [ 1 m ] in a ratio ranging from 2 : 5 to 2 : 10 , in order to incorporate the marker in the electrolyte . all this is done according to a previously drawn mask pattern . tungsten trioxide is deposited onto the structure using the same pattern that was employed for depositing the electrolyte , with the corresponding tolerances associated with the etching method used , by means of a physical deposition technique , such as resistive thermal evaporation , electron gun thermal evaporation , sputtering , or by a chemical process , such as ink - jet printing , or sol - gel , or pyrolysis , or deep coating , at temperatures ranging from 20 ° c . to 450 ° c . in the case of the physical techniques , the film growth ratios can be very high , larger than 3 nm / s , and the process costs can be very low , namely in the case of resistive thermal evaporation , when compared to other deposition techniques like electron gun - assisted thermal evaporation or sputtering . mounting a glass or other transparent inorganic or organic material on top of the device for encapsulation is an optional step , but it corresponds to the sealing and protecting process of the device with the purpose of making the operation thereof independent of the environmental conditions to which it is subjected . this encapsulation procedure can be carried out by means of any technique known in the field of product assembly processes , such as , for example , lamination . the major industries that presently might use the devices and circuits provided by using this innovation are the entire electronics industry , the semiconductor industry , the industry of flat displays and alike , the automotive industry , the paper industry , the advertising industry , the glass industry , the plastic industry , the instrumentation and sensor industry , the food industry , the medical and biotechnological industry , the optoelectronics industry , the micro - and nanoelectronics industry . an aspect of the presently disclosed subject matter is to replace the current electrochromic devices of the electrochromic diode type by electrochromic thin film transistors , which allow producing matrices with large areas wherein the pixel is the very channel region of the transistor that changes its colour , thereby allowing to build large areas shaped as a display that switch between the transparent or translucent or opaque or coloured states in periods of the order of a few seconds , compared to several dozens of minutes required to switch the transparency state of windows with more than 2 square meters in area . in addition , the change of the colour state is associated with a variation of the current flowing between the drain and the source of several orders of magnitude , providing the matrix with another active function that can be used to turn coloured advertisements and static or dynamic figures visible or invisible , similarly to what happens with the current liquid crystal displays ( lcd ) or with organic light emitting diodes ( oled ). on the other hand , the required technological manufacture processes are compatible with the ones already existing in the electronics , or optoelectronics , or semiconductor industries , namely the sputtering processes intended for large areas , or thermal evaporation , or sol - gel , or ink - jet , thereby not requiring large investments as far as research and technological adaptations are concerned . the technical advantages provided by the presently disclosed subject matter allow the active use of functionalized substrates either in a dynamic or static way , acting simultaneously as substrate and component of the electrochromic devices based on the same . although an exemplary embodiment has been described in detail , it should be understood that several variations , substitutions , and modifications can be made without departing from the scope of the presently disclosed subject matter , even if all the advantages identified above are not present . the embodiments presented herein illustrate the presently disclosed subject matter , which can be implemented and incorporated in a variety of different forms that fit in the scope thereof . also the techniques , constructions , elements , and processes described and illustrated in an exemplary embodiment as being distinct or separated can be combined with or integrated into other techniques , constructions , elements , or processes , without departing from the scope of the invention . although the presently disclosed subject matter has been described in various embodiments , these can still be modified according to the application scope of the presently disclosed subject matter . other examples of variations , substitutions , and modifications can be easily determined by those skilled in the art , and could be inserted without departing from the spirit and scope of the presently disclosed subject matter . zhang xuping , zhang haokang , li qing , and luo hongli , “ an all - 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