WO2019063707A1 - Self-powered electrochromic display device and method for the production thereof - Google Patents

Self-powered electrochromic display device and method for the production thereof Download PDF

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Publication number
WO2019063707A1
WO2019063707A1 PCT/EP2018/076295 EP2018076295W WO2019063707A1 WO 2019063707 A1 WO2019063707 A1 WO 2019063707A1 EP 2018076295 W EP2018076295 W EP 2018076295W WO 2019063707 A1 WO2019063707 A1 WO 2019063707A1
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Prior art keywords
layer
electrode layer
functional group
ones
display device
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Application number
PCT/EP2018/076295
Other languages
French (fr)
Inventor
Moazzam ALI
Jan Sebastian JOACHIM
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Saralon Gmbh
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Publication of WO2019063707A1 publication Critical patent/WO2019063707A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • G02F1/153—Constructional details
    • G02F1/155—Electrodes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K9/00—Tenebrescent materials, i.e. materials for which the range of wavelengths for energy absorption is changed as a result of excitation by some form of energy
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • G02F1/153—Constructional details
    • G02F1/1533—Constructional details structural features not otherwise provided for
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/17—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on variable-absorption elements not provided for in groups G02F1/015 - G02F1/169
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • G02F1/1514—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material
    • G02F1/1516—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect characterised by the electrochromic material, e.g. by the electrodeposited material comprising organic material
    • G02F1/15165—Polymers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/15—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect
    • G02F2001/164—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on an electrochromic effect the electrolyte is made of polymers

Definitions

  • the present disclosure relates to an electrochromic display device which combines a battery system and an electrochromic system in one device.
  • Electrochromic display devices are known in prior art.
  • An Electrochromic display device includes electrochromic materials, which change their optical properties, such as colouration when an electrical potential is applied to the electrochromic display device.
  • the change in colour can be used to display images through the electrochromic display device, as mentioned in US 2010/0220378 Al, US 2014/0307302 Al and GB 1411692.5.
  • a typical electrochromic display device multiple layers are stacked one over another as shown in Fig. 1A and Fig. IB. Different layers of the electrochromic display device can be produced by printing methods using inks.
  • an electrochromic display device 100 as shown in Fig. 1A, comprises a transparent substrate 110. On a first surface 111 of the substrate 110 is provided a transparent and conducting layer 120. On top of the transparent and conducting layer 120 is provided a first electrode layer 130. The first electrode layer 130 is electrochemically and electrochromically active. On top of the first electrode layer 130 is provided an electrolyte layer 140. On top of the electrolyte layer 140 is provided a second electrode layer 150. The second electrode layer 150 is electrochemically active. On top of the second electrode layer is provided a conducting layer 160. Connecting the transparent and conducting layer 120 and the conducting layer 160 to a power source, causes a color change in the first electrode layer 130.
  • Fig. IB Different layers of the electrochromic display device 100, produced by printing method and by using inks, may delaminate over time, as shown in Fig. IB. Delaminated areas 170 occur because of weak adhesion of different layers. Generally, chemicals of one layer are bound to chemicals of another layer by Van der Waals bonds or by hydrogen bonds. It is known that these bonds are relatively weak in nature, which leads to the de lamination of different layers.
  • the electrochromic display device 100 needs an external power source to switch on the display. It is economical to integrate the power source into the electrochromic display device 100.
  • a power source integrated into an electrochromic display device is known in the prior art, as mentioned in US 2010/0220378 Al .
  • the present invention relates to a self-powered electrochromic display device.
  • the device comprises a transparent and electrically conducting layer provided on a first substrate.
  • a first electrode layer; with a first redox potential, is printed on the transparent and electrically conducting layer.
  • the first electrode layer comprises at least one electrochromic compound.
  • the at least one electrochromic compound comprises at least one first functional group.
  • a pattern defining layer is provided on the first electrode layer.
  • the pattern defining layer is optically transparent and electrically insulating and having at least one opening.
  • the pattern defining layer comprises at least one anchoring molecule (or polymer).
  • the anchoring molecule comprises at least two ones of a third functional group.
  • An electrolyte layer is provided on the pattern defining layer.
  • the electrolyte layer is in contact with the first electrode layer through the at least one opening.
  • the electrolyte layer comprises at least one second functional group.
  • Third ones of the at least one second functional group are covalently bonded with third ones of the at least one first functional group.
  • Second ones of the at least one third functional group are covalently bonded to second ones of the at least one second functional group.
  • First ones of the at least one third functional group form second covalent bond with first ones of the at least one first functional group.
  • a second electrode layer, with a second redox potential is provided on the electrolyte layer. The absolute difference of the first redox potential and the second redox potential is more than 0.4 Volt. Electrically shorting the first electrode layer and the second electrode layer through an external electrical switch causes the first electrode layer to change a color in at least one portion of the electrode layer defined by the at least one opening. In the self-powered electrochromic display device one layer is strongly and covalently bonded to another layer which enhances long term performance of the device.
  • the present invention further relates to a method of manufacture of a self- powered electrochromic display device.
  • the method comprises a step of printing a first electrode layer with a first redox potential on a first substrate using an ink, the ink comprising at least one electrochromic compound and at least one first functional group.
  • the method further comprises a step of printing a pattern defining layer on the first electrode layer using an ink, the ink being electrically insulating and having at least one opening.
  • the method further comprises a step of printing an electrolyte layer on the pattern defining layer using an ink, the ink being in contact with the first electrode layer through the at least one opening, and the ink being UV curable and comprising at least one second functional group.
  • the method further comprises a step of exposing the electrolyte layer to UV radiation to transform into a gel the electrolyte layer.
  • the exposing to UV radiation further forms third covalent bonds between third ones of the at least one second functional group and third ones of the at least one first functional group.
  • the method further comprises a step of providing a second electrode layer with a second redox potential on the electrolyte layer, the absolute difference of the first redox potential and the second redox potential being more than 0.4 Volt.
  • the method further comprises a step of providing a second substrate on the second electrode layer.
  • the step of exposing to UV radiation of the electrolyte layer may further comprise forming first covalent bonds and second covalent bonds.
  • the ink for printing the pattern defining layer may comprise at least one anchoring molecule, any one the at least one anchoring molecule comprising at least two ones of at least one third functional group.
  • First ones of the at least one third functional group may form the first covalent bonds with first ones of the at least one first functional group upon UV exposure.
  • Second ones of the at least one third functional group may form the second covalent bonds with second ones of the at least one second functional group upon UV exposure.
  • FIG. 1 A is a cross sectional view of a prior art electrochromic display device.
  • FIG. IB is a cross sectional view of a prior art electrochromic display device with delamination.
  • FIG. 2A is a cross sectional view of a self-powered electrochromic display device, in accordance with an aspect of the present invention.
  • FIG. 2B is a cross sectional view of a self-powered electrochromic display device, in accordance with another aspect of the present invention.
  • FIG. 2C is a cross sectional view of a self-powered electrochromic display device, in accordance with another aspect of the present invention.
  • FIG. 2D is a cross sectional view of a self-powered electrochromic display device, in accordance with another aspect of the present invention.
  • FIG. 3 is a flow chart showing a manufacturing process to produce the self- powered electrochromic display device according to one exemplary embodiment of the present disclosure.
  • the term "ink” as used in this disclosure refers to a material that is in liquid or semi-solid or, paste form. It will be understood that, after printing of an ink on a surface, a drying and/or curing process may be required to convert the ink into a solid or a gel form. Typically, heat and/or radiation are used for the drying and/or curing processes. The drying and/or curing processes can also be self-activated.
  • the term "functional group” as used in this disclosure refers to a specific group of atoms or bonds within a molecule or a polymer that are responsible for a specific chemical reaction. For example, in a conjugated polymer chain a double bond between two carbon atoms is called a funct ional group, which may participate in a radical reaction.
  • covalent bond refers to a chemical bond that involves sharing of electron pairs between atoms. For instance, the bond between hydrogen atom and the oxygen atom in a water molecule is a covalent bond.
  • the present invention relates to a self-powered electrochromic display device.
  • Fig. 2A shows a cross-sectional view of a self-powered electrochromic display device 200.
  • a first electrode layer 210 is provided on a first substrate 201.
  • An observer will view the self- powered electrochromic display device 200 from the top in FIG. 2A.
  • the first substrate 201 can be made of a transparent plastic, a transparent paper, or a glass. In another aspect of this disclosure, the first substrate 201 can be semi- transparent.
  • the first electrode layer 210 is electrically conducting, at least partially transparent, electrochemically active, and electrochromically active.
  • the first electrode layer comprises at least one first functional group 211.
  • the first electrode layer 210 comprises a plurality of at least one electrochromic compound 212. Some examples of the at least one electrochromic compound 212 are given in the paper Polymer 55 (2014) 5293-5304, "Recent advances in electrochromic polymers".
  • the at least one electrochromic compound 212 is electrochemically and electrochromically active.
  • the at least one electrochromic compound 212 may form a transparent and electrically conducting one of the first electrode layer 210.
  • the at least one electrochromic compound 212 may be a conjugated polymer.
  • the at least one electrochromic compound 212 may be PEDOT:PSS (Poly(2,3- dihydrothieno-l,4-dioxin)-poly(styrenesulfonate)) or PANI (polyaniline), which are both electrochemically and electrochromically active as well as transparent and electrically conducting.
  • PEDOT:PSS Poly(2,3- dihydrothieno-l,4-dioxin)-poly(styrenesulfonate)
  • PANI polyaniline
  • the first electrode 210 is mesoporous Ti02/viologen system, in which the at least one electrochromic compound 212 comprises a viologen.
  • the viologen is, in this aspect, the chromophore that changes a color during an electrochemical reaction.
  • the at least one electrochromic compound 212 may comprise the at least one first functional group 211.
  • the at least one first functional group 211 is a carbon-carbon double bond of the electrochromic compound 212, i.e. an alkenyl functional group.
  • Several ones of the at least one first functional group 211 may be arranged within any one of electrochromic compound 212 at positions spaced apart, for instance at different ends within the electrochromic compound 212.
  • an additive molecule or polymer may be added to the first electrode layer 210 as an additive for adhesion enhancement.
  • the plurality of the additive molecule or polymer may comprise the plurality of the at least one first functional group 211, which is a carbon-carbon double bond of the additive molecule or polymer.
  • Several ones of the at least one first functional group 211 may be arranged within any one of the additive molecule or polymer at positions spaced apart, for instance at different ends within the additive molecule or polymer.
  • the first electrode layer 210 has a first redox potential.
  • the redox potential, or more accurately the reduction potential, of a compound refers to its tendency to acquire electrons and thereby to be reduced.
  • the first redox potential of the first electrode layer 210 is equivalent to the redox potential of the electrochromic compound 212.
  • the first redox potential of the first electrode layer 210 is the combined (i.e. the effective) redox potential of all the materials present in the first electrode layer 210.
  • the first electrode layer 210 is produced by printing an ink, which results in a wet printed layer. Subsequently, the wet printed layer undergoes drying and/or curing, thus turning the wet printed layer into a solid layer.
  • a pattern defining layer 220 is provided on the first electrode layer 210.
  • the pattern defining layer 220 is optically transparent and electrically insulating.
  • the pattern defining layer 220 comprises at least one opening 225.
  • the pattern defining layer 220 comprises a plurality of an anchoring molecule (or polymer) 222 and a plurality of at least one third functional group 221. Any one(s) of the anchoring molecule 222 comprise(s) at least two ones of the at least one third functional group 221.
  • the at least two ones of the at least one third functional group 221 may be arranged at positions spaced apart within the anchoring molecule 222, for instance at different ends within the anchoring molecule 222.
  • the at least one third functional group 221 is selected from the group of acrylate, methacrylate, thiol and combinations thereof.
  • Some non-limiting examples of the anchoring molecule 222 are allyl methacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane trimethacrylate, and UV curable resins.
  • a thiol group 221 and an alkenyl group 211 react with each other at room temperature and form covalent bonds.
  • an acrylate group 221 or a methacrylate group 221 reacts with an alkenyl group in the presence of UV radiation and an initiator.
  • the pattern defining layer 220 is produced by printing an ink, which results in a wet printed layer. Subsequently, the wet printed layer undergoes drying and/or curing, turning the wet printed layer into a solid layer.
  • the pattern defining layer 220 is not soluble in water and prevents movements of ions and electrons.
  • An electrolyte layer 230 is provided on the pattern defining layer 220.
  • the electrolyte layer 230 is in contact with the first electrode layer 210 through the at least one opening 225.
  • the electrolyte layer 230 is produced by an UV curable ink.
  • the electrolyte layer 230 comprises a plurality of at least one second functional group 231.
  • Second ones 231b, located adjacently to the pattern defining layer 220, of the at least one second functional group 231 form second covalent bonds 237 with second ones 221b, located adjacently to the electrolyte layer 230, of the at least one third functional group 221.
  • the electrolyte layer 230 comprises at least one salt, at least one UV curable polymer or molecule 232 and water.
  • the at least one second functional group 231 may be comprised in the UV curable polymer or molecule 232.
  • the UV curable polymer or molecule 232 is water soluble, e.g. 2-hydroxyethyl methacrylate or acrylated polyethylene oxide etc.
  • the at least one second functional group 231 is selected from a group of acrylate, methacrylate and combinations thereof.
  • the electrolyte layer 230 can further comprise pigment particles.
  • the purpose of the pigment particle is to provide a background colour to the electrochromic display.
  • the wet layer is converted into a gel or semisolid electrolyte layer 230 by UV radiation curing.
  • the gel or semi- so lid electrolyte layer 230 comprises at least 5 weight % of water.
  • the covalent bonds 235, 236 and 237 are formed during UV radiation curing of the electrolyte layer 230.
  • a second electrode layer 240 with a second redox potential On the electrolyte layer 230 is provided a second electrode layer 240 with a second redox potential.
  • the second redox potential is different from the first redox potential so that an electrochemical reaction can take place between the first electrode layer 210 and the second electrode layer 240.
  • the absolute difference of the first redox potential of the first electrode layer 210 and the second redox potential of the second electrode layer 240 is more than 0.4 Volt. It has been observed that if the absolute difference of the first redox potential and the second redox potential is less than 0.4 Volt, the switching on time of the electrochromic display is very long i.e. the electrochromic display is too slow.
  • the second electrode layer 240 comprises at least one of zinc, iron, steel, aluminum, copper, nickel, chromium, Mn02, Mg02, Sn, Li, AgO, CuO, Cu20, and Sn02.
  • the electrochromic display device 200 zinc particles are present in the second electrode layer 240, PEDOT:PSS is present in the first electrode layer 210, and zinc chloride salt is present in the electrolyte layer 230.
  • the voltage generated (open-circuit voltage) by the electrochromic display device 200 is around 1.15 Volt.
  • the first redox potential of the first electrode layer 210 is around 0.35 Volt
  • the second redox potential of the second electrode layer 240 is around 0.8 Volt.
  • the second electrode layer 240 can be produced by printing an ink onto the electrolyte layer 230, resulting in a wet layer, and subsequent drying and/or curing of the wet layer to form a solid layer.
  • the second electrode layer 240 is electrically conducting.
  • the second electrode layer 240 may be supported on a second substrate 202.
  • the electrical conductivity of the second electrode layer may be achieved by adding metallic and/or carbon particles to the layer.
  • the second substrate 202 can be plastic, paper, glass, wood or a laminate made of these materials.
  • the second electrode layer 240 can be produced by a step of printing an ink on the second substrate 202, resulting in a wet layer, and a subsequent drying and/or curing of the wet layer to form a solid layer.
  • a further step of laminating the second substrate 202 to the first substrate 201, with the first electrode layer 210, the pattern forming layer 220, the electrolyte layer 230, and the second electrode layer 240 interposed therebetween, as shown in FIG. 2A the second electrode layer 240 comes into contact with the electrolyte layer 230.
  • the first electrode layer 210 and the second electrode layer 240 are electrically connected to a first conducting layer 270 and a second conducting layer 280, respectively.
  • the first conducting layer 270 and the second conducting layer 280 are produced by using an electrically conducting ink e.g. silver ink, carbon ink etc.
  • the first conducting layer 270 is provided on the first substrate 201
  • the second conducting layer 280 is provided on the second substrate 202.
  • the first conducting layer 270 and the second conducting layer 280 are connected to an external electrical switch 290. Closing the external electrical switch 290 causes an electrochemical reaction to occur between the first electrode layer 210 and the second electrode layer 240. This causes the first electrode layer 210 to change a color in at least one portion of the electrode layer 210 that substantially overlaps with and/or is adjacent to the at least one opening 225.
  • Fig. 2B shows a cross-sectional view of a further aspect of the self-powered electrochromic display device 200.
  • the first electrode layer 210 differs from the first electrode layer 210 of the aspect shown in Fig. 2A, as described below.
  • first electrode layer 210 comprises a transparent and conducting layer 260 as well as an electrochemically active electrochromic layer 261.
  • the transparent and conducting layer 260 is provided on the first substrate 201.
  • the transparent and conducting layer 260 is interposed between the first substrate 201 and the electrochemically active electrochromic layer 261.
  • the transparent and conducting layer 260 is an oxide based layer e.g. indium-tin oxide, fluorine doped tin oxide, aluminum zinc oxide etc.
  • the transparent and conducting layer 260 is a transparent and conducting polymer e.g. PEDOT:PSS, PANI etc.
  • the electrochemically active layer 261 is provided on the transparent and conducting layer 260.
  • the electrochemically active electrochromic layer 261 comprises the at least one electrochromic compound 212.
  • the at least one electrochromic compound 212 may be one of some examples given in Polymer 55 (2014) 5293-5304, "Recent advances in electrochromic polymers".
  • Another non- limiting example of the electrochromic compound 212 is PEDOT:PSS.
  • the electrochromic compound 212 is electrochemically and electro chromically active.
  • the first redox potential of the electrochemically active electrochromic layer 261 may be the redox potential of the electrochromic compound 212. In this aspect, the first redox potential of the electrochemically active electrochromic layer 261 may be the combined (effective) redox potential of all the materials present in the electrochemically active electrochromic layer 261.
  • the transparent and conducting layer 260 layer may be electrochemically active. In this aspect, the first redox potential will be equal to the combined (effective) redox potential of all the materials present in the electrochemically active electrochromic layer 261 and the transparent and conducting layer 260 layer. The redox potential can be experimentally determined.
  • the electrochemically active electrochromic layer 261 is produced by printing an ink and then drying and/or curing of the wet layer into a solid layer.
  • the transparent and conducting layer 260 can be produced, for example, by a vacuum deposition of doped oxide layer e.g. indium tin oxide.
  • the transparent and conducting layer 260 can be produced by printing a nanoparticle based ink e.g. indium tin oxide nanoparticle based ink.
  • the transparent and conducting layer 260 and the second electrode layer 240 are connected to first conducting layer 270 and a second conducting layer 280, respectively.
  • the first conducting layer 270 and the second conducting layer 280 are connected to an external electrical switch 290. Closing the external electrical switch 290 causes electrochemical reaction between the first electrode layer 210 and the second electrode layer 240. This causes the electrochemically active electrochromic layer 261 to change a color in at least one portion of the electrode layer 210 that substantially overlaps with and/or is adjacent to the at least one opening 225.
  • Fig. 2C shows a cross-sectional view of a further aspect of the self-powered electrochromic display device 200.
  • the second electrode layer 240 differs from the first electrode layer 240 of the aspect shown in Fig. 2A, as described below.
  • the second electrode layer 240 comprises an electrochemically active layer 251 and a back conducting layer 250.
  • the electrochemically active layer 251 is provided on the electrolyte layer 230.
  • the back conducting layer 250 is provided on the electrochemically active layer 251.
  • the back conducting layer 250 may be printed on the electrochemically active layer 251.
  • the second substrate 202 is provided on the back conducting layer 250 for support.
  • the back conducting layer 250 is provided on the second substrate 202.
  • the back conducting layer 250 may be produced by printing a conducting ink (silver or carbon based ink) on the second substrate 202 and by subsequent drying and/or curing of the wet layer, which turns the wet layer into a solid layer. Then the electrochemically active layer 251 is printed on the back conducting layer 250.
  • the first electrode layer 210 and the back conducting layer 250 are connected to first conducting layer 270 and a second conducting layer 280, respectively.
  • the first conducting layer 270 and the second conducting layer 280 are connected to an external electrical switch 290. Closing the external electrical switch 290 causes electrochemical reaction between the first electrode layer 210 and the electrochemically active layer 251. This causes the first electrode layer 210 to change a color in at least one portion of the electrode layer 210 that substantially overlaps with and/or is adjacent to the at least one opening 225.
  • Fig. 2D shows a cross-sectional view of a further aspect of the self-powered electrochromic display device 200.
  • both the first electrode layer 210 and the second electrode layer 240 differ from the first electrode layer 240 and the second electrode layer 240 of the aspect shown in Fig. 2A, as described below.
  • the first electrode layer 210 of this aspect shares all features with the first electrode layer 210 of the aspect shown in Fig. 2B.
  • the second electrode layer 240 of this aspect shares all features with the second electrode layer 240 of the aspect shown in Fig. 2C.
  • the self-powered electrochromic display device 200 can be produced according to the following exemplary process, as illustrated in FIG. 3.
  • a first electrode layer 210 is printed on a first substrate 201 using an ink.
  • the first substrate 201 can be optically transparent or semi-transparent.
  • the first substrate 201 is electrically conducting.
  • the ink used for printing the electrode layer 210 comprises a plurality of at least one electrochromic compound 212 and a plurality of at least one first functional group 211. Several ones of the at least one first functional group 211 may be comprised in any one of the electrochromic compound 212.
  • the first electrode layer has a first redox potential.
  • a step 315 of drying and/or curing the printed first electrode layer 210 is carried out.
  • the step 315 of drying and/or curing is done in order to convert a wet layer of the first electrode 210 into a solid layer of the first electrode layer 210.
  • the step 310 of providing the first electrode layer 210 may comprise printing a transparent and conducting layer 260 on the first substrate 201, and subsequently printing an electrochemically active electrochromic layer 261 on the transparent and conducting layer 260.
  • a pattern defining layer 220 is printed on the first electrode layer 210 using an ink.
  • the pattern defining layer 220 is electrically insulating and has at least one opening 225.
  • the ink used for printing the pattern defining layer 230 comprises a plurality of at least one anchoring molecule 222. Any one of the at least one anchoring molecule 222 comprises at least two ones of at least one second functional group 231.
  • an electrolyte layer 230 is printed on the pattern defining layer 220 using an ink.
  • the printed electrolyte layer 230 is in contact with the first electrode layer 210 through the at least one opening 225.
  • the ink used for printing the electrolyte layer 230 is an UV curable ink and comprises a plurality of at least one second functional group 231, at least one salt and water.
  • a step 340 the electrolyte layer 230 is exposed by UV radiation to make a gel of electrolyte layer and create covalent bonds 235, 236 and 237.
  • Third ones 231c of the at least one second functional group 231 located adjacently to the first electrode layer 210, form third covalent bonds 235 with third ones 211c, located adjacently to the electrolyte layer 230, of the at least one first functional group 211
  • Second ones 231b, located adjacently to the pattern defining layer 220, of the at least one second functional group 231 form second covalent bonds 237 with second ones 221b, located adjacently to the electrolyte layer 230, of the at least one third functional group 221.
  • a second electrode layer 240 with a second redox potential is provided.
  • the second electrode layer 240 may be printed on the electrolyte layer 230 using an ink.
  • the step 350 of providing of the second electrode layer 240 may comprise first printing an electrochemically active layer 251 on the electrolyte layer 230 and subsequently printing a back conducting layer 250 on the electrochemically active layer 251.
  • the absolute difference of the first redox potential and the second redox potential is more than 0.4 Volt.
  • first electrode layer 210 and the second electrode layer 240 Electrically shorting the first electrode layer 210 and the second electrode layer 240 through an external electrical switch 290 causes the first electrode layer 210 to change a color in at least one portion of the electrode layer 210 that overlaps with and/or is adjacent to the at least one opening 255.
  • a second substrate 202 is provided on the second electrode layer 240.
  • the first electrode layer 210 and the second electrode layer 240 are electrically connected to a switch 290, the switch 290 being adapted to electrically connect the first electrode layer 210 and the second electrode layer 240.
  • an electrical current may flow between the first electrode layer 210 and the second electrode layer 240, cause a change of a color in at least one portion of the electrode layer 210 that overlaps with and/or is adjacent to the at least one opening 255.
  • the step 350 of providing the second electrode layer 240 may comprise printing the second electrode layer 240 on the second substrate 202 using an ink.
  • the step 360 of providing the second substrate 202 may comprise laminating the first substrate 201 and the second substrate 202 together, with the first electrode layer 210, the patterning defining layer 220, the electrolyte layer 230, and the second electrode layer 240 interposed therebetween.

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Abstract

A self-powered electrochromic display device is taught. A first electrode layer, with a first redox potential, is provided on a first substrate. The first electrode layer comprises a plurality of at least one electrochromic compound and a plurality of at least one first functional group. A pattern defining layer is provided on the first electrode layer. An electrolyte layer is provided on the pattern defining layer. The electrolyte layer is in contact with the first electrode layer through the at least one opening. The electrolyte layer comprises a plurality of at least one second functional group. Some of the at least one second functional group are covalently bonded with some of the at least one first functional group. A second electrode layer, with a second redox potential, is provided on the electrolyte layer. Electrically shorting the first electrode layer and the second electrode layer through an external electrical switch causes the first electrode layer to change its color of an area that is overlapping with the at least one opening. Covalent bonds between chemicals of one layer to chemicals of another layer makes adhesion stronger and hence enhances performance of the device.

Description

TITLE
Self-powered electrochromic display device and method for the production thereof CROSS-RELATION TO OTHER APPLICATIONS
[0001] This application claims priority of GB patent application GB 1715616.7, filed on 27 September 2017. The entire disclosure of GB Patent Application GB 1715616.7, is hereby incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present disclosure relates to an electrochromic display device which combines a battery system and an electrochromic system in one device.
BACKGROUND OF THE INVENTION
[0003] Electrochromic display devices are known in prior art. An Electrochromic display device includes electrochromic materials, which change their optical properties, such as colouration when an electrical potential is applied to the electrochromic display device. The change in colour can be used to display images through the electrochromic display device, as mentioned in US 2010/0220378 Al, US 2014/0307302 Al and GB 1411692.5.
[0004] In a typical electrochromic display device, multiple layers are stacked one over another as shown in Fig. 1A and Fig. IB. Different layers of the electrochromic display device can be produced by printing methods using inks.
[0005] For example, an electrochromic display device 100, as shown in Fig. 1A, comprises a transparent substrate 110. On a first surface 111 of the substrate 110 is provided a transparent and conducting layer 120. On top of the transparent and conducting layer 120 is provided a first electrode layer 130. The first electrode layer 130 is electrochemically and electrochromically active. On top of the first electrode layer 130 is provided an electrolyte layer 140. On top of the electrolyte layer 140 is provided a second electrode layer 150. The second electrode layer 150 is electrochemically active. On top of the second electrode layer is provided a conducting layer 160. Connecting the transparent and conducting layer 120 and the conducting layer 160 to a power source, causes a color change in the first electrode layer 130. [0006] Different layers of the electrochromic display device 100, produced by printing method and by using inks, may delaminate over time, as shown in Fig. IB. Delaminated areas 170 occur because of weak adhesion of different layers. Generally, chemicals of one layer are bound to chemicals of another layer by Van der Waals bonds or by hydrogen bonds. It is known that these bonds are relatively weak in nature, which leads to the de lamination of different layers.
[0007] As mentioned above, the electrochromic display device 100 needs an external power source to switch on the display. It is economical to integrate the power source into the electrochromic display device 100. A power source integrated into an electrochromic display device is known in the prior art, as mentioned in US 2010/0220378 Al .
SUMMARY OF THE INVENTION
[0008] The present invention relates to a self-powered electrochromic display device.
[0009] The device comprises a transparent and electrically conducting layer provided on a first substrate. A first electrode layer; with a first redox potential, is printed on the transparent and electrically conducting layer. The first electrode layer comprises at least one electrochromic compound. The at least one electrochromic compound comprises at least one first functional group.
[00010] A pattern defining layer is provided on the first electrode layer. The pattern defining layer is optically transparent and electrically insulating and having at least one opening. The pattern defining layer comprises at least one anchoring molecule (or polymer). The anchoring molecule comprises at least two ones of a third functional group.
[00011] An electrolyte layer is provided on the pattern defining layer. The electrolyte layer is in contact with the first electrode layer through the at least one opening. The electrolyte layer comprises at least one second functional group.
[00012] Third ones of the at least one second functional group are covalently bonded with third ones of the at least one first functional group. Second ones of the at least one third functional group are covalently bonded to second ones of the at least one second functional group. First ones of the at least one third functional group form second covalent bond with first ones of the at least one first functional group. [00013] A second electrode layer, with a second redox potential, is provided on the electrolyte layer. The absolute difference of the first redox potential and the second redox potential is more than 0.4 Volt. Electrically shorting the first electrode layer and the second electrode layer through an external electrical switch causes the first electrode layer to change a color in at least one portion of the electrode layer defined by the at least one opening. In the self-powered electrochromic display device one layer is strongly and covalently bonded to another layer which enhances long term performance of the device.
[00014] The present invention further relates to a method of manufacture of a self- powered electrochromic display device.
[00015] The method comprises a step of printing a first electrode layer with a first redox potential on a first substrate using an ink, the ink comprising at least one electrochromic compound and at least one first functional group.
[00016] The method further comprises a step of printing a pattern defining layer on the first electrode layer using an ink, the ink being electrically insulating and having at least one opening.
[00017] The method further comprises a step of printing an electrolyte layer on the pattern defining layer using an ink, the ink being in contact with the first electrode layer through the at least one opening, and the ink being UV curable and comprising at least one second functional group.
[00018] The method further comprises a step of exposing the electrolyte layer to UV radiation to transform into a gel the electrolyte layer. The exposing to UV radiation further forms third covalent bonds between third ones of the at least one second functional group and third ones of the at least one first functional group.
[00019] The method further comprises a step of providing a second electrode layer with a second redox potential on the electrolyte layer, the absolute difference of the first redox potential and the second redox potential being more than 0.4 Volt.
[00020] The method further comprises a step of providing a second substrate on the second electrode layer.
[00021] The step of exposing to UV radiation of the electrolyte layer may further comprise forming first covalent bonds and second covalent bonds. The ink for printing the pattern defining layer may comprise at least one anchoring molecule, any one the at least one anchoring molecule comprising at least two ones of at least one third functional group. First ones of the at least one third functional group may form the first covalent bonds with first ones of the at least one first functional group upon UV exposure. Second ones of the at least one third functional group may form the second covalent bonds with second ones of the at least one second functional group upon UV exposure.
BRIEF DESCRIPTION OF THE DRAWINGS
[00022] FIG. 1 A is a cross sectional view of a prior art electrochromic display device.
[00023] FIG. IB is a cross sectional view of a prior art electrochromic display device with delamination.
[00024] FIG. 2A is a cross sectional view of a self-powered electrochromic display device, in accordance with an aspect of the present invention.
[00025] FIG. 2B is a cross sectional view of a self-powered electrochromic display device, in accordance with another aspect of the present invention.
[00026] FIG. 2C is a cross sectional view of a self-powered electrochromic display device, in accordance with another aspect of the present invention.
[00027] FIG. 2D is a cross sectional view of a self-powered electrochromic display device, in accordance with another aspect of the present invention.
[00028] FIG. 3 is a flow chart showing a manufacturing process to produce the self- powered electrochromic display device according to one exemplary embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[00029] The invention will now be described in detail. Drawings and examples are provided for better illustration of the invention. It will be understood that the embodiments and aspects of the invention described herein are only examples and do not limit the protector's scope of the claims in any way. The invention is defined by the claims and their equivalents. It will be understood that features of one aspect or embodiment of the invention can be combined with the feature of a different aspect or aspects and/or embodiments of the invention. [00030] The terms "print," "printability," "printing," "printable" and "printed", as used in this disclosure, refer to production methods using functional inks. More specifically, these production methods include, but are not limited to, screen-printing, stencilling, flexography, gravure, off-set, thermal transfer and ink-jet printing. These printing methods can be roll-to- roll or sheet-fed or manual.
[00031] The term "ink" as used in this disclosure refers to a material that is in liquid or semi-solid or, paste form. It will be understood that, after printing of an ink on a surface, a drying and/or curing process may be required to convert the ink into a solid or a gel form. Typically, heat and/or radiation are used for the drying and/or curing processes. The drying and/or curing processes can also be self-activated.
[00032] The terms "compound", "polymer", "molecule", "water", and other designations, specific or general, like "water", "salt", "acrylate", "zinc", "Mn02", etc. refer to one or both of a chemical substance and a single particle of this chemical substance.
[00033] The term "functional group" as used in this disclosure refers to a specific group of atoms or bonds within a molecule or a polymer that are responsible for a specific chemical reaction. For example, in a conjugated polymer chain a double bond between two carbon atoms is called a funct ional group, which may participate in a radical reaction.
[00034] The term "covalent bond" refers to a chemical bond that involves sharing of electron pairs between atoms. For instance, the bond between hydrogen atom and the oxygen atom in a water molecule is a covalent bond.
[00035] The present invention relates to a self-powered electrochromic display device. Fig. 2A shows a cross-sectional view of a self-powered electrochromic display device 200. A first electrode layer 210 is provided on a first substrate 201. An observer will view the self- powered electrochromic display device 200 from the top in FIG. 2A.
[00036] The first substrate 201 can be made of a transparent plastic, a transparent paper, or a glass. In another aspect of this disclosure, the first substrate 201 can be semi- transparent.
[00037] The first electrode layer 210 is electrically conducting, at least partially transparent, electrochemically active, and electrochromically active. The first electrode layer comprises at least one first functional group 211. [00038] The first electrode layer 210 comprises a plurality of at least one electrochromic compound 212. Some examples of the at least one electrochromic compound 212 are given in the paper Polymer 55 (2014) 5293-5304, "Recent advances in electrochromic polymers". The at least one electrochromic compound 212 is electrochemically and electrochromically active. In one aspect, the at least one electrochromic compound 212 may form a transparent and electrically conducting one of the first electrode layer 210. The at least one electrochromic compound 212 may be a conjugated polymer. In a further non- limiting aspect, the at least one electrochromic compound 212 may be PEDOT:PSS (Poly(2,3- dihydrothieno-l,4-dioxin)-poly(styrenesulfonate)) or PANI (polyaniline), which are both electrochemically and electrochromically active as well as transparent and electrically conducting.
[00039] In another aspect, the first electrode 210 is mesoporous Ti02/viologen system, in which the at least one electrochromic compound 212 comprises a viologen. The viologen is, in this aspect, the chromophore that changes a color during an electrochemical reaction.
[00040] The at least one electrochromic compound 212 may comprise the at least one first functional group 211. In one aspect, the at least one first functional group 211 is a carbon-carbon double bond of the electrochromic compound 212, i.e. an alkenyl functional group. Several ones of the at least one first functional group 211 may be arranged within any one of electrochromic compound 212 at positions spaced apart, for instance at different ends within the electrochromic compound 212.
[00041] In another aspect, an additive molecule or polymer may be added to the first electrode layer 210 as an additive for adhesion enhancement. The plurality of the additive molecule or polymer may comprise the plurality of the at least one first functional group 211, which is a carbon-carbon double bond of the additive molecule or polymer. Several ones of the at least one first functional group 211 may be arranged within any one of the additive molecule or polymer at positions spaced apart, for instance at different ends within the additive molecule or polymer.
[00042] The first electrode layer 210 has a first redox potential. The redox potential, or more accurately the reduction potential, of a compound refers to its tendency to acquire electrons and thereby to be reduced. In one aspect, the first redox potential of the first electrode layer 210 is equivalent to the redox potential of the electrochromic compound 212. In another aspect, the first redox potential of the first electrode layer 210 is the combined (i.e. the effective) redox potential of all the materials present in the first electrode layer 210.
[00043] The first electrode layer 210 is produced by printing an ink, which results in a wet printed layer. Subsequently, the wet printed layer undergoes drying and/or curing, thus turning the wet printed layer into a solid layer.
[00044] A pattern defining layer 220 is provided on the first electrode layer 210. The pattern defining layer 220 is optically transparent and electrically insulating. The pattern defining layer 220 comprises at least one opening 225. The pattern defining layer 220 comprises a plurality of an anchoring molecule (or polymer) 222 and a plurality of at least one third functional group 221. Any one(s) of the anchoring molecule 222 comprise(s) at least two ones of the at least one third functional group 221. The at least two ones of the at least one third functional group 221 may be arranged at positions spaced apart within the anchoring molecule 222, for instance at different ends within the anchoring molecule 222.
[00045] The at least one third functional group 221 is selected from the group of acrylate, methacrylate, thiol and combinations thereof. Some non-limiting examples of the anchoring molecule 222 are allyl methacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, trimethylolpropane trimethacrylate, and UV curable resins.
[00046] First ones 221a of the plurality of the at least one third functional group 221, located adjacently to the first electrode layer 210, form first covalent bonds 236 with first ones 211a, located adjacently to the pattern defining layer 220, of the plurality of the at least one first functional group 211. It is known in the literature that a thiol group 221 and an alkenyl group 211 react with each other at room temperature and form covalent bonds. It is also known in the literature that an acrylate group 221 or a methacrylate group 221 reacts with an alkenyl group in the presence of UV radiation and an initiator.
[00047] The pattern defining layer 220 is produced by printing an ink, which results in a wet printed layer. Subsequently, the wet printed layer undergoes drying and/or curing, turning the wet printed layer into a solid layer. The pattern defining layer 220 is not soluble in water and prevents movements of ions and electrons.
[00048] An electrolyte layer 230 is provided on the pattern defining layer 220. The electrolyte layer 230 is in contact with the first electrode layer 210 through the at least one opening 225. In an aspect of this disclosure, the electrolyte layer 230 is produced by an UV curable ink.
[00049] The electrolyte layer 230 comprises a plurality of at least one second functional group 231. Third ones 231c of the at least one second functional group 231, located adjacently to the first electrode layer 210, form third covalent bonds 235 with third ones 211c, located adjacently to the electrolyte layer 230, of the at least one first functional group 211.
[00050] Second ones 231b, located adjacently to the pattern defining layer 220, of the at least one second functional group 231 form second covalent bonds 237 with second ones 221b, located adjacently to the electrolyte layer 230, of the at least one third functional group 221.
[00051] The electrolyte layer 230 comprises at least one salt, at least one UV curable polymer or molecule 232 and water. The at least one second functional group 231 may be comprised in the UV curable polymer or molecule 232. In one aspect of the disclosure, the UV curable polymer or molecule 232 is water soluble, e.g. 2-hydroxyethyl methacrylate or acrylated polyethylene oxide etc. In a non-limiting aspect of this disclosure, the at least one second functional group 231 is selected from a group of acrylate, methacrylate and combinations thereof.
[00052] The electrolyte layer 230 can further comprise pigment particles. The purpose of the pigment particle is to provide a background colour to the electrochromic display. After printing a wet layer of the electrolyte layer 230, the wet layer is converted into a gel or semisolid electrolyte layer 230 by UV radiation curing. In one aspect of the disclosure, the gel or semi- so lid electrolyte layer 230 comprises at least 5 weight % of water.
[00053] The covalent bonds 235, 236 and 237 are formed during UV radiation curing of the electrolyte layer 230.
[00054] On the electrolyte layer 230 is provided a second electrode layer 240 with a second redox potential. The second redox potential is different from the first redox potential so that an electrochemical reaction can take place between the first electrode layer 210 and the second electrode layer 240. The absolute difference of the first redox potential of the first electrode layer 210 and the second redox potential of the second electrode layer 240 is more than 0.4 Volt. It has been observed that if the absolute difference of the first redox potential and the second redox potential is less than 0.4 Volt, the switching on time of the electrochromic display is very long i.e. the electrochromic display is too slow.
[00055] In an aspect of the disclosure, the second electrode layer 240 comprises at least one of zinc, iron, steel, aluminum, copper, nickel, chromium, Mn02, Mg02, Sn, Li, AgO, CuO, Cu20, and Sn02.
[00056] In an aspect of the electrochromic display device 200, zinc particles are present in the second electrode layer 240, PEDOT:PSS is present in the first electrode layer 210, and zinc chloride salt is present in the electrolyte layer 230. The voltage generated (open-circuit voltage) by the electrochromic display device 200 is around 1.15 Volt. In this aspect, the first redox potential of the first electrode layer 210 is around 0.35 Volt, and the second redox potential of the second electrode layer 240 is around 0.8 Volt.
[00057] In a non-limiting aspect of this disclosure, the second electrode layer 240 can be produced by printing an ink onto the electrolyte layer 230, resulting in a wet layer, and subsequent drying and/or curing of the wet layer to form a solid layer.
[00058] The second electrode layer 240 is electrically conducting. The second electrode layer 240 may be supported on a second substrate 202. The electrical conductivity of the second electrode layer may be achieved by adding metallic and/or carbon particles to the layer. The second substrate 202 can be plastic, paper, glass, wood or a laminate made of these materials.
[00059] In a non-limiting aspect of this disclosure, the second electrode layer 240 can be produced by a step of printing an ink on the second substrate 202, resulting in a wet layer, and a subsequent drying and/or curing of the wet layer to form a solid layer. In a further step of laminating the second substrate 202 to the first substrate 201, with the first electrode layer 210, the pattern forming layer 220, the electrolyte layer 230, and the second electrode layer 240 interposed therebetween, as shown in FIG. 2A, the second electrode layer 240 comes into contact with the electrolyte layer 230.
[00060] The first electrode layer 210 and the second electrode layer 240 are electrically connected to a first conducting layer 270 and a second conducting layer 280, respectively. In an aspect of this disclosure, the first conducting layer 270 and the second conducting layer 280 are produced by using an electrically conducting ink e.g. silver ink, carbon ink etc. The first conducting layer 270 is provided on the first substrate 201, and the second conducting layer 280 is provided on the second substrate 202. The first conducting layer 270 and the second conducting layer 280 are connected to an external electrical switch 290. Closing the external electrical switch 290 causes an electrochemical reaction to occur between the first electrode layer 210 and the second electrode layer 240. This causes the first electrode layer 210 to change a color in at least one portion of the electrode layer 210 that substantially overlaps with and/or is adjacent to the at least one opening 225.
[00061] Fig. 2B shows a cross-sectional view of a further aspect of the self-powered electrochromic display device 200. In this aspect, the first electrode layer 210 differs from the first electrode layer 210 of the aspect shown in Fig. 2A, as described below.
[00062] In the aspect, shown in Fig. 2B, first electrode layer 210 comprises a transparent and conducting layer 260 as well as an electrochemically active electrochromic layer 261. The transparent and conducting layer 260 is provided on the first substrate 201. The transparent and conducting layer 260 is interposed between the first substrate 201 and the electrochemically active electrochromic layer 261.
[00063] In a non-limiting aspect of this disclosure, the transparent and conducting layer 260 is an oxide based layer e.g. indium-tin oxide, fluorine doped tin oxide, aluminum zinc oxide etc. In another aspect of this disclosure, the transparent and conducting layer 260 is a transparent and conducting polymer e.g. PEDOT:PSS, PANI etc.
[00064] The electrochemically active layer 261 is provided on the transparent and conducting layer 260. In an aspect of the disclosure, the electrochemically active electrochromic layer 261 comprises the at least one electrochromic compound 212. In the aspect shown in Fig. 2B, the at least one electrochromic compound 212 may be one of some examples given in Polymer 55 (2014) 5293-5304, "Recent advances in electrochromic polymers". Another non- limiting example of the electrochromic compound 212 is PEDOT:PSS. The electrochromic compound 212 is electrochemically and electro chromically active.
[00065] In this aspect of the disclosure, the first redox potential of the electrochemically active electrochromic layer 261 may be the redox potential of the electrochromic compound 212. In this aspect, the first redox potential of the electrochemically active electrochromic layer 261 may be the combined (effective) redox potential of all the materials present in the electrochemically active electrochromic layer 261. [00066] In a further aspect, the transparent and conducting layer 260 layer may be electrochemically active. In this aspect, the first redox potential will be equal to the combined (effective) redox potential of all the materials present in the electrochemically active electrochromic layer 261 and the transparent and conducting layer 260 layer. The redox potential can be experimentally determined. The electrochemically active electrochromic layer 261 is produced by printing an ink and then drying and/or curing of the wet layer into a solid layer. The transparent and conducting layer 260 can be produced, for example, by a vacuum deposition of doped oxide layer e.g. indium tin oxide. In another aspect, the transparent and conducting layer 260 can be produced by printing a nanoparticle based ink e.g. indium tin oxide nanoparticle based ink.
[00067] In the aspect shown in Fig. 2B, the transparent and conducting layer 260 and the second electrode layer 240 are connected to first conducting layer 270 and a second conducting layer 280, respectively. The first conducting layer 270 and the second conducting layer 280 are connected to an external electrical switch 290. Closing the external electrical switch 290 causes electrochemical reaction between the first electrode layer 210 and the second electrode layer 240. This causes the electrochemically active electrochromic layer 261 to change a color in at least one portion of the electrode layer 210 that substantially overlaps with and/or is adjacent to the at least one opening 225.
[00068] Fig. 2C shows a cross-sectional view of a further aspect of the self-powered electrochromic display device 200. In this aspect, the second electrode layer 240 differs from the first electrode layer 240 of the aspect shown in Fig. 2A, as described below.
[00069] In the aspect, shown in Fig. 2C, the second electrode layer 240 comprises an electrochemically active layer 251 and a back conducting layer 250. The electrochemically active layer 251 is provided on the electrolyte layer 230. The back conducting layer 250 is provided on the electrochemically active layer 251.
[00070] The back conducting layer 250 may be printed on the electrochemically active layer 251. The second substrate 202 is provided on the back conducting layer 250 for support.
[00071] In another aspect, the back conducting layer 250 is provided on the second substrate 202. The back conducting layer 250 may be produced by printing a conducting ink (silver or carbon based ink) on the second substrate 202 and by subsequent drying and/or curing of the wet layer, which turns the wet layer into a solid layer. Then the electrochemically active layer 251 is printed on the back conducting layer 250.
[00072] In the aspect shown in Fig. 2 the first electrode layer 210 and the back conducting layer 250 are connected to first conducting layer 270 and a second conducting layer 280, respectively. The first conducting layer 270 and the second conducting layer 280 are connected to an external electrical switch 290. Closing the external electrical switch 290 causes electrochemical reaction between the first electrode layer 210 and the electrochemically active layer 251. This causes the first electrode layer 210 to change a color in at least one portion of the electrode layer 210 that substantially overlaps with and/or is adjacent to the at least one opening 225.
[00073] Fig. 2D shows a cross-sectional view of a further aspect of the self-powered electrochromic display device 200. In this aspect, both the first electrode layer 210 and the second electrode layer 240 differ from the first electrode layer 240 and the second electrode layer 240 of the aspect shown in Fig. 2A, as described below. The first electrode layer 210 of this aspect shares all features with the first electrode layer 210 of the aspect shown in Fig. 2B. The second electrode layer 240 of this aspect shares all features with the second electrode layer 240 of the aspect shown in Fig. 2C.
[00074] The self-powered electrochromic display device 200 can be produced according to the following exemplary process, as illustrated in FIG. 3.
[00075] In a step 310, a first electrode layer 210 is printed on a first substrate 201 using an ink. The first substrate 201 can be optically transparent or semi-transparent. In a non- limiting aspect of this disclosure, the first substrate 201 is electrically conducting. The ink used for printing the electrode layer 210 comprises a plurality of at least one electrochromic compound 212 and a plurality of at least one first functional group 211. Several ones of the at least one first functional group 211 may be comprised in any one of the electrochromic compound 212. The first electrode layer has a first redox potential.
[00076] After a step 310 of printing the first electrode layer 210, a step 315 of drying and/or curing the printed first electrode layer 210 is carried out. The step 315 of drying and/or curing is done in order to convert a wet layer of the first electrode 210 into a solid layer of the first electrode layer 210. [00077] The step 310 of providing the first electrode layer 210 may comprise printing a transparent and conducting layer 260 on the first substrate 201, and subsequently printing an electrochemically active electrochromic layer 261 on the transparent and conducting layer 260.
[00078] In a step 320, a pattern defining layer 220 is printed on the first electrode layer 210 using an ink. The pattern defining layer 220 is electrically insulating and has at least one opening 225. The ink used for printing the pattern defining layer 230 comprises a plurality of at least one anchoring molecule 222. Any one of the at least one anchoring molecule 222 comprises at least two ones of at least one second functional group 231.
[00079] In the step 330, an electrolyte layer 230 is printed on the pattern defining layer 220 using an ink. The printed electrolyte layer 230 is in contact with the first electrode layer 210 through the at least one opening 225. The ink used for printing the electrolyte layer 230 is an UV curable ink and comprises a plurality of at least one second functional group 231, at least one salt and water.
[00080] In a step 340, the electrolyte layer 230 is exposed by UV radiation to make a gel of electrolyte layer and create covalent bonds 235, 236 and 237. Third ones 231c of the at least one second functional group 231 , located adjacently to the first electrode layer 210, form third covalent bonds 235 with third ones 211c, located adjacently to the electrolyte layer 230, of the at least one first functional group 211 Second ones 231b, located adjacently to the pattern defining layer 220, of the at least one second functional group 231 form second covalent bonds 237 with second ones 221b, located adjacently to the electrolyte layer 230, of the at least one third functional group 221. First ones 221a of the plurality of the at least one third functional group 221, located adjacently to the first electrode layer 210, form first covalent bonds 236 with first ones 211a, located adjacently to the pattern defining layer 220, of the plurality of the at least one first functional group 211.
[00081] In a step 350, a second electrode layer 240 with a second redox potential is provided. The second electrode layer 240 may be printed on the electrolyte layer 230 using an ink. In another aspect of the disclosure, the step 350 of providing of the second electrode layer 240 may comprise first printing an electrochemically active layer 251 on the electrolyte layer 230 and subsequently printing a back conducting layer 250 on the electrochemically active layer 251. The absolute difference of the first redox potential and the second redox potential is more than 0.4 Volt. Electrically shorting the first electrode layer 210 and the second electrode layer 240 through an external electrical switch 290 causes the first electrode layer 210 to change a color in at least one portion of the electrode layer 210 that overlaps with and/or is adjacent to the at least one opening 255.
[00082] In a step 360, a second substrate 202 is provided on the second electrode layer 240.
[00083] In a step 370, the first electrode layer 210 and the second electrode layer 240 are electrically connected to a switch 290, the switch 290 being adapted to electrically connect the first electrode layer 210 and the second electrode layer 240. Upon closing the electrical switch 290, an electrical current may flow between the first electrode layer 210 and the second electrode layer 240, cause a change of a color in at least one portion of the electrode layer 210 that overlaps with and/or is adjacent to the at least one opening 255.
[00084] In a further aspect, the step 350 of providing the second electrode layer 240 may comprise printing the second electrode layer 240 on the second substrate 202 using an ink. In this aspect, the step 360 of providing the second substrate 202 may comprise laminating the first substrate 201 and the second substrate 202 together, with the first electrode layer 210, the patterning defining layer 220, the electrolyte layer 230, and the second electrode layer 240 interposed therebetween.

Claims

1. A self-powered electrochromic display device (200), comprising:
- a first electrode layer (210) with a first redox potential, comprising at least one electrochromic compound (212) and at least one first functional group (211);
- a pattern defining layer (220), provided on the first electrode layer (210), the pattern defining layer (220) being electrically insulating and having at least one opening (225);
- an electrolyte layer (230), provided on the pattern defining layer (220), the electrolyte layer (230) being in contact with the first electrode layer (210) through the at least one opening (225), the electrolyte layer (230) comprising at least one second functional group (231), third ones (231c) of the at least one second functional group (231) covalently bonded (235) with third ones (211c) of the at least one first functional group (211); and
- a second electrode layer (240) with a second redox potential provided on the electrolyte layer (230), the absolute difference of the first redox potential and the second redox potential being larger than 0.4 Volt; wherein the first electrode layer (210) and the second electrode layer (240) are electrically connected to an external electrical switch (290), the external electrical switch (290) being adapted to electrically connect the first electrode layer (210) to the second electrode layer (240).
2. The self-powered electrochromic display device (200) as claimed in claim 1, wherein the at least one second functional group (231) is selected from a group of acrylate, methacrylate and a combination thereof, and the at least one first functional group (211) is an alkenyl functional group.
3. The self-powered electrochromic display device (200) as claimed in claim 1, wherein the at least one electrochromic compound (212) is a conjugated polymer.
4. The self-powered electrochromic display device (200) as claimed in claim 1, wherein the first electrode layer (210) and the second electrode layer (240) are electrically conducting.
5. The self-powered electrochromic display device (200) as claimed in claim 1, wherein the pattern defining layer (220) comprises a plurality of at least one anchoring molecule (222), wherein any one of the plurality of the at least one anchoring molecule (222) comprises at least two ones of the at least one third functional group (221), the at least two ones of the at least one third functional group (221) being selected from a group of acrylate, methacrylate, thiol and combinations thereof, first ones (221a) of the plurality of the at least one third functional group (221) forming first covalent bonds (236) with first ones (211a) of the at least one first functional group (211), second ones (221b) of the at least one third functional group (221) forming second covalent bonds (237) with second ones (231b) of the at least one second functional group (231).
The self-powered electrochromic display device (200) as claimed in claim 1, wherein the electrolyte layer (230) comprises at least 5 weight % of water.
A method of manufacturing a self-powered electrochromic display device (200), comprising the steps of: a. printing (310) a first electrode layer (210) with a first redox potential on a first substrate (201) using an ink, the ink comprising a plurality of at least one electrochromic compound (212) and at least one first functional group (211); b. printing (320) a pattern defining layer (220) on the first electrode layer (210) using an ink, the ink being electrically insulating and having at least one opening (225); c. printing (330) an electrolyte layer (230) on the pattern defining layer (220) using an ink, the ink being in contact with the first electrode layer (210) through the at least one opening (225), the ink being UV curable and comprising at least one second functional group (231); d. exposing (340) the electrolyte layer (230) to UV radiation to transform the electrolyte layer (230) into a gel, and to form third covalent bonds (235) between third ones (23 lc) of the at least one second functional group (231) and third ones (211c) of the at least one first functional group (211); and e. providing (350) a second electrode layer (240) with a second redox potential on the electrolyte layer (230), the absolute difference of the first redox potential and the second redox potential being more than 0.4 Volt; f. providing (360) a second substrate (202) on the second electrode layer (240); g. electrically connecting (370) the first electrode layer (210) and the second electrode layer (240) to a switch (290) adapted to electrically connect the first electrode layer (210) and the second electrode layer (240).
8. The method of claim 7, wherein the exposing (340) to UV radiation of the electrolyte layer (230) further comprises forming first covalent bonds (236) and second covalent bonds (237), wherein the ink for printing the pattern defining layer (220) comprises at least one anchoring molecule (222), any one the at least one anchoring molecule (222) comprising at least two ones of at least one third functional group (221), first ones (221a) of the at least one third functional group (221) forming the first covalent bonds (236) with first ones (211a) of the at least one first functional group (211) upon UV exposure, second ones (221b) of the at least one third functional group (221) forming the second covalent bonds (237) with second ones (231b) of the at least one second functional group (231) upon UV exposure.
9. The method of claim 7, wherein the at least one second functional group (231) and the at least one third functional group (221) are selected from a group of acrylate, methacrylate, thiol and combinations thereof, the at least one first functional group (211) is alkenyl functional group.
PCT/EP2018/076295 2017-09-27 2018-09-27 Self-powered electrochromic display device and method for the production thereof WO2019063707A1 (en)

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Citations (2)

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US20140307302A1 (en) * 2011-11-07 2014-10-16 Acreo Swedish Ict Ab Vertical electrochromic display
WO2016161147A1 (en) * 2015-04-03 2016-10-06 The Regents Of The University Of Colorado, A Body Corporate Conductive polymeric compositions and applications

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JP5486924B2 (en) * 2006-06-23 2014-05-07 イー・アイ・デュポン・ドウ・ヌムール・アンド・カンパニー Electrochromic electrolyte blend
JP2009175718A (en) * 2007-12-28 2009-08-06 Fujifilm Corp Electrodeposition method light modulating device and electrodeposition method reflective display device
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US20140307302A1 (en) * 2011-11-07 2014-10-16 Acreo Swedish Ict Ab Vertical electrochromic display
WO2016161147A1 (en) * 2015-04-03 2016-10-06 The Regents Of The University Of Colorado, A Body Corporate Conductive polymeric compositions and applications

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