WO2007113190A1

WO2007113190A1 - Electrochromic formulation, electrochromic switchable component

Info

Publication number: WO2007113190A1
Application number: PCT/EP2007/052984
Authority: WO
Inventors: Andreas Kanitz; Wolfgang Roth
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-03-31
Filing date: 2007-03-28
Publication date: 2007-10-11
Also published as: EP2001971A1

Abstract

The invention relates to a formulation for an electrochromic component, in particular a component which can be switched in an irreversible or virtually irreversible manner. The invention also relates to the use of such a formulation and to an electrochromic component which can be switched in an irreversible manner.

Description

description

Electrochromic formulation, electrochromic switchable ^component

The invention relates to a formulation for a elektrochro ^¬ mes component particularly one that irreversibly or almost mistaken ^¬ is reversibly switchable. Moreover, the invention relates to an electrochromic component which is irreversibly switchable.

Electrochromic formulations for electrochromic devices, such as displays based on organic materials, form within the device at least one layer which is located between electrodes arranged perpendicular to one another. Essential components of this formulation are a redox system and a pH-active dye. When a voltage is applied to the system, then the runs Ver ^¬ shift the equilibrium of redox partners at the two electrodes in the opposite direction. As a result, the pH of one of the electrodes rises while it sinks on the counter electrode. Via a pH dye, the change in pH is then converted into a color change.

From DE 10 2005 031 634.4 is a material for a formulation of a electrochromic active layer of an electronic device known to th a polymeric Festelektroly ^¬, a supporting electrolyte, a redox system, a white pigment, a solvent and comprises a dye at least, wherein the functionalities of the solid polymer electrolyte, chromophore and conducting salt are present together as one component in the formulation.

It is further known from DE 10 2005 031 635.2, a material for an electrochromic formulation the at least one polymer as a solid electrolyte, a supporting electrolyte, a redox system, a white pigment, a solvent and a Chro ^¬ mophor, wherein the functionality of the redox -System and the chromophore are connected in one component. The described formulations are designed for a large number of switching cycles, ie reversible color changes. This makes them particularly suitable for display ads that display time-varying information.

The disadvantage, however, is that they are for disposable products, so for example disposable displays, z. B. for visualization of a system state, are not suitable, since the displayed state of the display, for. B. a color impression is retained only for a short time. System state is any physical parameter such. As understood the temperature and / or pressure.

The object of the invention is, therefore, an electrochromic Formu ^{¬-regulation} to provide an electrochromic device for the active layer, which overcomes the disadvantages of the prior art over ^¬ and is suitable for visualizing a system state.

The invention relates to an electrochromic formulation for the active layer of an electrochromic component, wherein the color change produced by the application of voltage either remains intact or lasts for at least four hours in the de-energized state. In addition, the invention also relates to the use of the formulation for electrochromic components such as, for example, electrochromic display elements, as well as electrochromic components which are irreversibly switchable or which contain a formulation of the subject matter of the invention.

These are z. As displays that monitor the state of a system and the exceeding of z. B. indicate irreversible limits. Thus, monitoring a physical parameter see a system possible in which an over ^¬ a target / limit underrange occurs. The detection of the ^¬ ses value is effected by means of suitable sensors, the meter is exceeded at Para ^¬ generate an electrical signal, the egg NEN irreversible color change of the electrochromic display element triggers. Measured values can be z. As the temperature, the pressure or the relative humidity. Furthermore, a combination of the mentioned parameters is possible.

The formulations change irreversibly from one color state to another when an electrical voltage is applied. Irreversible in this context means that the Umpo ^¬ the electrochromic cell len not the original color state again, or after hours again can be achieved. The signal triggered by a sensor generates a color impression which is retained even in the currentless case. As usual, such formulations consist of a white pigment such as titanium dioxide and a solvent. The irreversibly reacting system is one that can not return to its original state due to a chemical reaction and / or thermodynamic or kinetic inhibition. Such reactions are known in chemistry, especially in analytical chemistry. However, these reactions usually proceed in an aqueous medium, often requiring a certain pH or pH range.

Surprisingly, these reactions also take place in a pasty environment, such. B. suitable for electrochromic applications formulations suitable for use in electrochromic devices.

One embodiment of the formulation is based on the use of metal salts, preferably those from the series of transition metals. The choice of the anion is not restricted be ^¬. Of the class of inorganic anions, however, are those of the series of halides, of the class of organic anions, acetates are preferred. The metal ions present in the formulation are reduced in the electrochromic cell at the cathode to elemental metal, resulting in a dark gray to black color impression as a result of the formed dispersively distributed metal. In the event of a colorless metal salt a particularly large ^¬ SSSR color contrast. However, colored Me ^¬ metal salts can be used, in which case a color change be- see the corresponding color of the dissolved salt in the formulation and the color of the resulting metal dispersive, that is, a dark color impression is produced. When reversing the e-lektrochromen cell, the metal atoms at the cathode, which is now the anode, no longer oxidized to the ion, so that the dark color impression remains. Since the original anode has become the cathode after the polarity reversal, the color impression from bright to dark also takes place here.

Another embodiment of the invention is based on the oxidation of the iodine anion to elemental iodine at the anode. Since the iodine salt in the formulation is colorless in the dissolved state, the iodine formed at the anode produces a dark brown to black color impression. This can be enhanced by the presence of starch in the formulation. As iodine salts z. As from the series of Alkalime ^¬ metals, in particular potassium iodide suitable.

Another embodiment of the invention is based on the irreversible addition of bromine to fluorescein. The bromine is formed by oxidation of bromide present in the formulation at the anode. This bromine is added to irreversibly Fluo ^¬ rescein whereby tetrabromo-fluorescein (Eosin) is formed. This results in an irreversible color change from yellow to red. As Bromsalze z. As suitable from the series of alkali metals, in particular potassium bromide.

Another embodiment is based on 4.4

Bipyridinium salts, as are known from DE 10 2005 032 316.2. These switch reversibly in the electric field between two color impressions. However, this reversibility can be greatly delayed by a suitable matrix. Surprisingly, a suitable matrix is one of anhydrous glycerol or one containing anhydrous glycerol. This delays after a switching operation, the return of the electrochromic cell in the initial state by many hours. To obtain the desired color impression, therefore, only an occasional voltage pulse is necessary.

In the following the invention will be explained in more detail with reference to a figure:

The figure shows a schematic structure of a elektrochro ^¬ men component, on a substrate 1 is the lower electrode 2, thereon the at least one active layer 3 and thereon the upper electrode 4. The entire component is surrounded by a Verkap- be 5.

embodiments

1 Preparation of an irreversibly reactive formulation based on a metal reduction

6 g of titanium dioxide and 0.6 g of cobalt (II) chloride are intimately mixed with 2.7 g of diethylene glycol by means of a speed mixer. It is obtained a whitish, pasty formulation.

Production of an electrochromic cell

The resulting formulation, white, pasty is applied according to the prior art between ITO-coated glass or fle ible ^¬ plastic substrates. When a voltage is applied between the electrodes, a color change to dark gray / black is observed at the cathode. When reversing the polarity of the electrochromic cell this color impression remains, it now also arises at the other electrode. The dark color impression persists for weeks even when de-energized. 2 Preparation of an irreversibly reactive formulation based on the oxidation of iodide to iodine

3g of water-soluble starch are intimately mixed with 0.3 g of potassium iodide using a speed mixer. To 1.5g of water are added and tergemischt also using a speed mixer intensively un ^¬. It will receive a bright, pasty formulation.

Production of an electrochromic cell

The pasty formulation obtained is applied according to the prior art between ITO-coated glass or flexible plastic ^¬ plastic substrates. When a voltage is applied between the electrodes, a color change to dark brown / black is observed at the cathode. When reversing the polarity of the electrochromic cell, this color impression persists; it now also forms on the other electrode. The dark color ^¬ remains impressive even exist when de-energized for weeks.

3 Preparation of an irreversibly reactive formulation based on the irreversible addition of bromine

1.5g water-soluble starch are mixed with 0.03g and 0.1g of potassium bromide Fluorescein using a speed mixer intimately ^¬ ver. For this Ig water is intensively mixed by means of a Speedmixer. This gives a light brown, pasty Formulie ^¬ tion. Production of an electrochromic cell

The resulting light brown, pasty formulation is applied according to the prior art between ITO-coated glass or flexible plastic substrates. When a voltage is applied between the electrodes, a color change to dark brown / black is observed at the cathode. When umpo ^¬ len the electrochromic cell this color impression remains, it now also arises at the other electrode. The dark color impression persists for weeks even when de-energized.

4 Preparation of an irreversibly reacting formulation based on 4, 4-bipyridinium salts, as are known from DE 10 2005 032 316:

6 g of titanium dioxide and 0.6 g of a 4, 4-Bipyridiniumsalzes be mixed intensively by means of a speed mixer. For this purpose, a mixture of 2.2 g of diethylene glycol and 1.6 g of anhydrous glycerine is intensively mixed in by means of a speed mixer. A white, pasty formulation is obtained.

Production of an electrochromic cell

The obtained white, pasty formulation is applied according to the prior art between ITO-coated glass or flexible plastic substrates. When a voltage is applied between the electrodes, a color change from white to dark blue is observed at the cathode. When de-energized, this color impression persists for at least 8-100 hours. By a short voltage pulse after 8-1oh the color impression can be maintained over a long period of time.

The invention provides a formulation for an electrochromic component, or an electrochromic device is first provided by a one-time display realizable ^¬ bar. This is especially true for applications of display packaging of perishable goods, such as food or medicines, of high economic importance.

The invention relates to a formulation for a elektrochro- mes component specifically one that irreversibly or almost mistaken ^¬ is reversibly switchable. Moreover, the invention relates to the use of such a formulation and an electrochromic component which is irreversibly switchable.

Claims

claims

1. Electrochromic formulation for the active layer of an electrochromic device, at least one colorant

Component and a charge transport component contained ^¬ tend, wherein the color change produced by the application of voltage of the coloring component, either remains in the free state or voltage ^¬ holding at least four hours.

2. Formulation according to claim 1, which is in the form of a paste.

3. Formulation according to claim 1, which contains at least one metal or halide salt as coloring component, wherein by applying a voltage to the formulation of the metal salt by cathodic reduction elemental metal or by anodic oxidation elemental halogen is releasable.

4. A formulation according to any one of claims 1 or 2, wherein a transition metal salt is included in the formulation as a coloring component.

5. A formulation according to any one of the preceding claims, wherein a bromide and / or a iodide salt is contained.

6. A formulation according to any one of the preceding claims, wherein as coloring component at least one 4,4-

Bipyridinium salt in a matrix which comprises at least anhydrous glycerin is included.

7. Use of a formulation according to any one of the preceding claims for the production of an electrochromic component.

8. Electrochromic component which is irreversibly switchable.

9. An electrochromic device which contains in the active layer to ^¬ least a formulation according to any one of claims 1 to. 6

10. An electrochromic device according to claim 8 or 9, which is a display or a display device.

11. Electrochromic component according to one of claims 8 to 10, which together with further electronic components forms an electronic device.

12. The electrochromic component according to claim 11, wherein the electronic device comprises at least one display and one sensor, which are electrically conductively connected to one another.

13. Electrochromic component according to one of claims 8 to

12, which is part of a perishable goods package.