DE19834834A1 - Self-adhesive electrochromic electrode and arrangements containing it - Google Patents

Abstract

The invention relates to a self-adhesive electrochromic electrode which contains a substrate having an electrically conductive coating and made of glass or a plastic material, an electrochromic, polymeric organic material and an adhesive layer, as well as to electrochromic systems fitted with such an electrode.

Description

The present invention relates to an electrochromic electrode which has an adhesive layer contains, as well as equipped with such an electrode electrochromic arrangement conditions and their use.

Electrochromic materials change their color through oxidation and reduction processes. In an electrochromic arrangement, the electrochromic material and the ion-storing counter electrode by an ion-conducting gel electrolyte interconnected so that charge transport takes place between the layers can. The optical properties of the electrochromic material change through Redox processes that involve the exchange of ions, such as protons or Metal ions such as lithium ions can be linked. So the metal ions can the ion storage is released from the structure under the influence of an electric field be placed or stored. By changing the polarity of the applied field the effect can be reversed, which brings the electrochromic material back into its returns to its original optical condition.

Electrochromic adhesive layers for electrochromic applications based on inorganic metal oxides, for example WO ₃ , are described in WO 97/40419.

The object of the present invention was to develop electrochromic adhesive layers, instead of the cumbersome to manufacture electrochromic metal oxides should contain easily applied organic, polymeric electrochromic layers, which do not show any cracking even under bending stress on flexible substrates, as was previously the case with inorganic metal oxide layers.

It has now been found that adhesive layers with an electrochromic polymer, at for example poly (3,4-ethylenedioxy-thiophene), meet this requirement.  

An object of the invention is a self-holding electrochromic electrode holding an electrically conductive coated substrate made of glass or plastic, that is rigid or flexible and can be designed as a tape or a film, an elek trochrome, polymeric, organic material and an adhesive layer.

The electrochromic electrode preferably contains a peel off on the adhesive layer bare protective layer, which can be formed continuously or discontinuously.

The adhesive layer can be designed as a single or multi-layer construction and shows adhesive or adhesive properties under ambient conditions or develops such properties, for example by swelling with solvents or by the influence of elevated temperature or pressure. The adhesive layer contains preferably an ion-storing material.

An ion storage material is a material that has a microstructure that it ions, preferably protons or metal ions, especially lithium ions allows to be stored reversibly, the storage or retrieval can be caused by an applied electric field.

The adhesive layer can be such that the ion-storing material either shows self-adhesive or adhesive properties, or that the ion spit material with one or more additional materials in the form of sepa advise layers or as a mixture with the ion-storing material with the result that the combined construction is adhesive or sticky Shows properties.

In a preferred construction, the ion-storing material is between the Arranged substrate and the removable protective layer. Preferred in another The structure is the electrochromic material and an ion-conducting polymer gel. Electrolyte arranged between the substrate and the removable protective layer. The Protective layer can each represent a low-energy surface, which is can be easily obtained without damaging the underlying functional layer. The detention  layer is preferably a pressure-sensitive layer, i. H. when pressing on a The base should adhere to the layer.

The term "electrochromic material" as used herein refers to an organic polymeric material (preferably polydioxythiophene) that reduces or can be oxidized and can also contain embedded ions.

The polydioxythiophenes are preferably cationically charged and from structural units of the formula (I)

built in the
A ¹ and A ² independently of one another represent optionally substituted (C ₁ -C ₄ ) alkyl or together form optionally substituted (C ₁ -C ₄ ) alkylene, and
n represents an integer from 2 to 10,000, preferably 5 to 5,000,
and preferably contain polyanions as counterions.

Preferred cationic polydioxythiophenes are composed of structural units of the formula (Ia) or (Ib)

wherein
R ₁ and R ₂ independently of one another for hydrogen, optionally substituted (C ₁ -C ₁₈ ) -alkyl, preferably (C ₁ -C ₁₀ ) -, in particular (C ₁ -C ₆ ) -alkyl, (C ₂ -C ₁₂ ) Alkenyl, preferably (C ₂ -C ₈ ) alkenyl, (C ₃ -C ₇ ) cycloalkyl, preferably cyclopentyl, cyclohexyl, (C ₇ -C ₁₅ ) aralkyl, preferably phenyl (C ₁ -C ₄ ) alkyl, (C ₆ -C ₁₀ ) aryl, preferably phenyl, naphthyl, (C ₁ -C ₁₈ ) alkyloxy, preferably (C ₁ -C ₁₀ ) alkyloxy, for example methoxy, ethoxy, n- or iso-propoxy, or (C ₂ -C ₁₈ ) alkyloxy ester and
R ₃ , R ₄ independently of one another for Wasserstott with at least one sulfonate group substituted (C ₁ -C ₁₈ ) alkyl, preferably (C ₁ -C ₁₀ ), in particular (C ₁ -C ₆ ) alkyl, (C ₂ -C ₁₂ ) Alkenyl, preferably (C ₂ -C ₈ ) alkenyl, (C ₃ -C ₇ ) cycloalkyl, preferably cyclopentyl, cyclohexyl, (C ₇ -C ₁₅ ) aralkyl, preferably phenyl (C ₁ -C ₄ ) -alkyl, (C ₆ -C ₁₀ ) aryl, preferably phenyl, naphthyl, (C ₁ - C ₁₈ ) alkyloxy, preferably (C ₁ -C ₁₀ ) alkyloxy, for example methoxy, ethoxy, n- or iso-propoxy or (C ₂ -C ₁₈ ) alkyloxy ester.
n stands for a number from 2 to 10,000, preferably 5 to 5,000.

The electrochromic device structure according to the invention very particularly preferably contains at least one electrically conductive, electrochromic cationic or neutral poly dioxythiophene of the formulas (Ia-1) and / or (Ib-1)

wherein
R _{3 has} the meaning given above.
n represents an integer from 2 to 10,000, preferably 5 to 5,000.

The anions of polymeric carboxylic acids, such as polyacrylic acid, serve as polyanions ren, polymethacrylic acids, or polymaleic acids and polymeric sulfonic acids, such as Polystyrene sulfonic acids and polyvinyl sulfonic acids. This polycarbonate and sulfonic acid Ren can also copolymers of vinyl carbon and vinyl sulfonic acids with others polymerizable monomers, such as acrylic acid esters and styrene.

The anion of the polystyrene sulfonic acid is particularly preferred as the counter ion.

The molecular weight of the polyacids providing the polyanions is preferred wise 1,000 to 2,000,000, particularly preferably 2,000 to 500,000. The polyacids or their alkali salts are commercially available, for example polystyrene sulfonic acids  and polyacrylic acids, or can be prepared by known processes (see Houben Weyl, Methods of Organic Chemistry, Vol. E 20 Macromolecular Substances, Part 2, (1987), p. 1141 and others).

Instead of that for the formation of the dispersions from polydioxythiophenes and polyanio NEN required free polyacids, you can also mixtures of alkali salts Use polyacids and appropriate amounts of monoacids.

In the case of the formula (Ib1), the polydioxythiophenes carry positive and negative La in the structural unit. The preparation of the polydioxythiophenes is for example in EP-A 0 440 957 (= US-A 5 300 575).

The polydioxythiophenes are obtained by oxidative polymerization. Thereby they get positive charges that are not shown in the formulas because of their number and their position cannot be determined properly.

For example, the electrochromic material can be poly (3,4-ethylenedioxythiophene) (PEDT), poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDT / PSS) or the respective forms with embedded ions, preferably protons or metal ions, especially lithium ions.

Preferred electrochromic electrodes include as the electrochromic material electrically conductive polymer, preferably from the substance class of poly (3,4- dioxythiophenes).

Another preferred electrochromic electrode contains ion storage materials, preferably V ₂ O ₅ , Nb ₂ O ₅ , Li _x V ₂ O ₅ , Li ₂ Nb ₂ O ₅ or nickel oxides. In a preferred construction, the electrochromic or ion-storing material itself has no adhesive or adhesive property, but rather ion-conducting polymer gel electrolytes applied to it.

A preferred preferred substrate according to the invention is polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) or flexible glass, each of which is provided with a transparent, electrically conductive coating. The flexible substrate can also be reflective. For example, it can contain a metal layer such as silver as a reflective layer. The transparent, electrically conductive coating can consist of indium tin oxide (ITO), tin dioxide (SnO ₂ ) or fluorine-doped tin dioxide (SnO ₂ : F), as well as a sufficiently thin metal coating, for example silver.

The invention also relates to an electrochromic arrangement which comprises the invention contains self-adhesive electrochromic electrode. In it is a second electrically conductive capable substrate in contact with the self-adhesive electrode described above brought.

The second electrically conductive system can preferably be a rigid substrate, for example wise contain glass, provided with a transparent electrically conductive layer is.

If the self-adhesive electrode contains an electrochromic polymer such as PEDT / PSS and an ion-conducting polymeric gel electrolyte, the second substrate preferably contains an ion storage material, for example V ₂ O ₅ , Li _x V ₂ O ₅ or a nickel oxide. If the self-adhesive electrode contains the ion storage material, for example V ₂ O ₅ , Li _x V ₂ O ₅ or a nickel oxide and a polymeric gel electrolyte, the second substrate preferably contains the electrochromic polymer, for example PEDT / PSS.

In a preferred embodiment, the invention relates to an electrochromic type order, which is a polymeric electrochromic material, preferably from the sub punch class of poly- (3,4-ethylenedioxythiophenes), and an ion-storing ion storage material includes an ion-conducting polymer gel electrolyte layer are separated from each other, with one substrate made of glass, the second of flexible plastic or vice versa and both substrates can be made of plastic  nen. The polymeric, ion-conducting gel electrolyte preferably takes over Function of the adhesive or adhesive layer.

In a further embodiment, the invention relates to a glazing unit that

• a) contains an electrochromic arrangement consisting of an electrochromic layer is built up between two electrically conductive substrates, one of two substrates rigid and transparent and the second flexible and transparent is or
• b) contains an electrochromic arrangement consisting of an electrochromic layer between two flexible and transparent electrically conductive substrates is built up and optionally encapsulated film composite system between rigid or flexible transparent substrates can be embedded or
• c) contains an electrochromic arrangement according to a) or b) and additionally one contains another third substrate, both for the first and for the second Substrate has no direct contact, but through a gas layer or Vacuum is separated to form a heat transfer barrier.

In all cases a), b) and c) the electrochromic arrangement contains an organic one polymeric electrochromic material, preferably from the substance class of poly (3,4-dioxythiophenes), especially the poly (3,4-ethylenedioxythiophenes), an ion embedding ion storage material and an ion conducting polymer gel electro lyten, which separates the first two materials. The gel Electrolyte also prefers the function of the adhesive or adhesive layer.

Flexible adhesive tapes, foils etc. as in the electrochromic arrangement according to the present invention, offer a variety of advantages against about existing systems related to the manufacture of complete electrochro orders. So the flexible tapes or films in the form of rolls  delivered and assembled on site to the desired size, for example by cutting. In addition, the present concept offers the possibility of Production of large-area arrangements, for example for electrochromic fen most in the architectural or automotive sector ("smart windows").

FIG. 1A illustrates an electrochromic arrangement 10 which is formed from a rigid and a flexible substrate, which are partially separated from one another. The actual electrochromic functional layers are not shown here.

Fig. 1B is an enlarged cross-sectional view of the overall construction of the elec trochromen assembly 10 with all the necessary layers.

The figure shows a tape or film 12 on a flexible substrate 16 with a transparent electrically conductive layer 18 , 20 showing the ion storage material and 22 the ion-conducting gel electrolyte. The flexible substrate 16 is preferably PET, PEN or flexible glass. The transparent electrical conductor 18 is preferably indium tin oxide (ITO), tin dioxide (SnO ₂ ), fluorine-doped tin dioxide (SnO ₂ : F) or a metal, for example silver. Flexible substrates of this type with a conductive coating are known and some are commercially available.

The ion storage material 20 is an ion-intercalating material which can store ions, preferably protons or metal ions, in particular lithium ions, and release them again by applying an electrical potential. Suitable ion storage materials for this purpose consist in vanadium or niobium oxide compounds or in mixtures thereof, or in nickel oxides.

V ₂ O ₅ , Nb ₂ O or nickel oxide is preferably used here. A polymer electrolyte is preferred as the ion-conducting gel electrolyte 22 , which has the property of being adhesive or pressure-sensitive.

In addition to the ion transport, the electrolyte 22 also serves to adhere the tape or film 12 to the rigid substrate 14 . It preferably conducts metal ions back and forth between the ion storage material 20 and the electrochromic polymer material 28 , depending on the polarity of the applied electrical voltage. Thin barrier layers, which are not shown in FIG. 1B, can separate the electrolyte 22 from the ion storage material 20 and thereby increase the life of the electrochromic arrangement. Niobium oxide is an example of a suitable barrier layer.

A very particularly preferred base material for the gel electrolyte 22 is the crosslinked polymerization product of lithium ion-conducting monomers, oligomers or polymers. Photocrosslinking when exposed to light is very particularly preferred. The polymer can be swollen with solvent, very particularly before propylene carbonate, and even after crosslinking, the surface can be wetted with solvent for better adhesion. The electrolyte system can already contain metal ions, very particularly preferably lithium ions, during the crosslinking. The rigid, flexible substrate 14 , very particularly preferably based on glass, polycarbonate or PET as 24 , contains an electrically conductive layer 26 , and the polymeric electrochromic material 28 , particularly preferably poly (3,4-ethylenedioxythiophene).

The optical properties of the electrochromic material 28 can be changed by applying an electrical voltage to the layers 18 and 26 and by changing the polarity.

The most suitable electrochromic material 28 is the poly (3,4-ethylenedioxythiophene) polystyrene sulfonate PEDT / PSS. An aqueous dispersion of this material is available as Baytron P® (Bayer AG, Leverkusen).

FIG. 2B schematically shows the manufacturing process of an electrochromic device using the adhesive tapes or films of the invention. The tape 30 consists of a flexible substrate 32 , which is provided with a transparent electrically conductive layer 34 , an ion storage material 36 , a thin barrier layer 38 and a pressure-sensitive or adhesive polymeric ion-conducting gel electrolyte 40 . The peelable protective layer 42 protects the surface of the adhesive electrolyte layer 40 and is peeled off prior to the lamination of the tape 30 onto a flexible or rigid substrate 44 . The substrate 46 can be glass or plastic and can be rigid or flexible. The substrate 44 is provided with an electrically conductive coating 48 , which can also be specular, and with a polymeric electrochromic layer 50 .

A second structure of an electrochromic arrangement according to the invention is shown in FIG. 2A. The band 52 consists of a flexible substrate 54 with an electrically conductive coating 56 , the electrochromic polymer material 58 and the pressure-adhering or adhesive polymeric ion-conducting gel electrolyte layer 60 . The latter is protected from damage by the peelable protective layer 62 , which is peeled off prior to lamination to the substrate 64 . The substrate 64 consists of a flexible or rigid glass or plastic substrate 66 , which is provided with an electrically conductive layer 68 , which can also be specular, an ion storage material 70 and a barrier layer 72 .

The ion storage layer and the electrochromic polymer material can on the respective substrates can be applied using known techniques, for example by casting and subsequent tempering, or in the case of the ion storage by vapor deposition, sputtering or electrochemically. For the production of the ions storage layer is made to DE-A 198 10 931. To manufacture the electro chrome layer, reference is made to DE-A 198 10 932.

The polymer electrolyte can be applied to the surface of the tape in the form of light poly merizable monomers or coated in the form of prepolymers, wherein the tape is then preferably laminated onto the second substrate and then networking with light takes place. However, the crosslinking reaction can also before laminating. However, the electrolyte can also be in the form an adhesive or adhesive polymer system using known conventional Methods such as casting or coating, for example roll-coating, on the upper  Apply the surface of the tape. The tape can then lay on the second substrate be mined.

The electrochromic arrangement, which is manufactured according to the above-mentioned methods, can also be integrated into a glazing unit according to FIG. 3. The glazing solution unit 80 is distinguished by the fact that it consists of a pair of rigid transparent substrates, for example glass or plastic, 82 and 84 , which are kept apart by means of the spacer 86 . The gap between substrates 82 and 84 defines a thermal barrier that defines the insulation properties of the glazing unit. One of the two substrates is provided with a transparent electrically conductive layer 88 and is part of the electrochromic arrangement, characterized in that it contains the electrochromic polymer material 90 (e.g. poly (3,4-ethylenedioxythiophene) and the ion storage material 94 (e.g. V ₂ O ₅ , Nb ₂ O ₅ or nickel oxide), both of which are separated from one another by the polymer gel electrolyte layer 92. A substrate 98 which can be flexible and is provided with a transparent electrically conductive coating 96 is shown in Contact to the ion storage material 94 and completes the complete electrochromic structure In use, the electrochromic arrangement is connected to a voltage source by means of known contacting measures on the conductive layers 88 and 96 .

The glazing unit, which can also consist of curved substrates 84 and 82 , can also be designed so that the substrate 98 is flexible and the gap between the substrates 84 and 82 is so small that no cavity is formed. Rather, the substrate 98 can also be in contact with the substrate 82 .

The glazing unit 80 is produced, for example, by the method described above. The electrochromic polymer 90 is applied to the conductive side 88 of the substrate 84 and the tape, which comprises the substrate 98 , the transparent conductive layer 96 , the ion storage material 94 and the polymeric gel electrolyte 92 , is then laminated onto the electrochromic polymer layer. Alternatively, the polymeric gel electrolyte can also be applied to the electrochromic polymer layer and would therefore not be part of the tape. In another variant, the electrochromic polymer material can also be part of the tape instead of the ion storage material.

The self-adhesive electrode according to the invention can be used to build up an electrochromic arrangement in the

• - Architectural glazing "smart windows", sun roofs,
• - Glazing in the mobile area, for example in the automotive sector at Son roofs, tintable windows in the front, rear and side areas, Safety laminated glass systems,
• - Ads, for example for advertising material, posters,
• - variably configurable field boundary lines in sports halls.

The invention is illustrated by the following examples.

Examples example 1 Production of an ion storage layer (V ₂ O ₅ ) a) Preparation of a sol solution for producing the ion storage layer

2.5 g of ammonium vanadate NH ₄ (VO ₃ ) are dissolved in 25 g of water and 37.5 g of the ion exchanger ®Lewatit S100 (Bayer AG, Leverkusen, Germany) are added. The mixture is then stirred at room temperature for 10 minutes. Then, with rapid stirring, another 475 g of water are added and stirring is continued for 10 minutes. The mixture is filtered off and the solution obtained is left to stand for 24 hours at room temperature for aging. Finally, 0.25 g of the wetting agent Fluortensid® FT 248 (Bayer AG, Leverkusen) is added. This solution is ready to use.

b) gel process

The solution from Example 1a) is on the conductive side of indium / Zirmoxid coated polyethylene terephthalate (ITO-PET) applied and with the varnish spin produces a uniform layer of the sol (10 sec. at 1000 rpm). Then you anneal at 60 ° C for 24 hours. The layer thickness measurement with the Profilometer showed 10 to 20 nm.

Example 2 Construction of an electrochromic film system

Applying an electrochromic polymer to an ITO-PET substrate:
The polymer Baytron P (aqueous dispersion of the conductive polymer PEDT / PSS, polyethylenedioxythiophene-polystyrene sulfonate, Bayer AG, Leverkusen) is made from an aqueous solution with a varnish spinner 4 times with 15 seconds each at a rotation speed of 1500 rpm on the electrical conductive side of an ITO-PET film applied. During the application, the solvent is evaporated off using a hair dryer.

A transparent, only slightly bluish-colored polymer film is obtained. A Measurement of the layer thickness with a profilometer gave a value of 0.6 µm.

Production of a gel electrolyte

7.7 g of the unsaturated aliphatic urethane acrylate Roskydal® UA VP LS 2258 (Bayer AG) together with 0.1925 g (2.5% by weight) of Darocure photoinitiator 1173 from Merck, Darmstadt and 0.3 g (3% by weight) of lithium trifluoromethanesulfo nat from Aldrich mixed in 2 g of dry 1,2-propylene carbonate from Aldrich. This mixture is pourable and can be cross-linked photochemically, which means a no longer flowable gel electrolyte can be produced.

Production of the gel electrolyte layer

The still uncrosslinked gel electrolyte is applied to the ion storage layer from example 1 applied with a wet film thickness of 200 µm and with the electrochromic PEDT- Layer from example 2 brought into contact: This composite is made with a belt run speed of 20 m / min under UV radiation (IST lamp) promotes. This crosslinks the gel electrolyte. You get a film system, wel ches a no longer flowing gel electrolyte and is transparent.

This electrochromic film system is examined in more detail in Example 3.  

Example 3 Function test on the electrochromic film system

The electrochromic cell from Example 2 is in each case at the ITO layers with 2.0 V DC voltage contacted for a short time before then the polarity of the electrical Control changes. This results in a cyclical coloring and decolorization of the Cell. At the same time, one observes the change in transmission over time through the cell.

Example 4 Delamination of the layer composite

The electrochromic electrode with PEDT in the layer composite from Example 2 is velvet of the ITO-PET substrate carefully removed from the hardened gel electrolyte layer pulled. The electrode with the ion storage remains after delamination layer that is coated with the gel electrolyte layer.

Example 5 Laminating the layer composite

The two electrode sides (ITO-PET / V ₂ O ₅ / gel electrolyte and PEDT / ITO-PET) are joined together, whereby a slight pressure with a spherical body is sufficient to ensure renewed contact between the gel electrolyte and the PEDT Layer. Analogously to example 3, the layer composite is contacted and the transmission through the composite is measured (see FIG. 4).

Claims (12)

1. Self-adhesive electrochromic electrode containing an electrically conductive coated substrate made of glass or plastic, an electrochromic, polyme res, organic material and an adhesive layer. 2. Electrode according to claim 1, characterized in that the substrate flexi at is. 3. Electrode according to claim 1, characterized in that as a flexible Substrate polyethylene terephthalate (PET), polyethylene naphthylate (PEN) or flexible glass is included, with indium tin oxide, tin dioxide, fluorine doped tin dioxide or coated with a metal conductive. 4. Electrode according to claim 1, characterized in that the adhesive layer consists of an ion-conducting polymeric gel electrolyte. 5. Electrode according to claim 1, characterized in that the electrochromic Material is an electrically conductive polymer. 6. Electrode according to claim 1, characterized in that the electrochromic Material is poly (3,4-ethylenedioxythiophene). 7. Electrode according to claim 1, characterized in that on the detention additional protective layer is attached. 8. Electrode according to claim 2, characterized in that it is in the form of a Band or a film is formed. 9. electrochromic arrangement containing the electrode according to claim 1 in Combination with a rigid or flexible substrate that is electrically contains conductive coating and an ion storage layer.   10. Use of the arrangement according to claim 9 in architectural glazing. 11. Use of the arrangement according to claim 9 in vehicle windows. 12. Use of the arrangement according to claim 9 in display devices.