JPS5936247B2 - electrical display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device in which a display electrode and a counter electrode are brought into contact with an electrolytic solution containing an organic compound that can be electrochemically reversibly redoxed.

An electrochemically reversible oxidation-reducible organic compound such as a viologen compound (4,4'-bipyridine derivative) is dissolved in an inert solvent together with a supporting electrolyte to form an electrolytic solution, in which at least one pair consisting of a display electrode and a counter electrode is disposed. A display device having a structure in which a pair of electrodes is immersed is known [Applied Physics Letters (Appl, Phys,
Lett, ), Volume 23, No. 2, Pages 64-65] This display device uses an electrochemical reversible redox reaction of a viologen compound to apply a negative voltage to the display electrode. An image is thus formed.

This redox reaction is thought to proceed according to the following reaction formula. (In the formula, R is a substituent and 0 which combines with anions to form an insoluble salt () and exhibits a reddish-purple color.
This reaction is reversible; by reversing the polarity of the electrodes, the insoluble salt () is removed from the initial viologen cation (1
).

Therefore, it is possible to form an image by utilizing the formation of the reddish-purple insoluble salt (1), and to erase the image by utilizing the restoration to the viologen cation (1).

However, in display devices using conventional viologen compounds, the image color is limited to only purple colors, and when the two pyridinium rings in the viologen compound are reduced together, it becomes a yellow and colored two-electron reduced product. Moreover, it has the disadvantage of short service life due to the generation of irreversible reduced products. The present inventors have improved the disadvantages of conventional display devices and developed a display device with various color tones. can be colored,
In order to develop a display device with a long service life,
As a result of extensive research, we have found that electrochemically reversible redox-capable organic compounds with the general formula (where R is a hydrogen atom or a hydrocarbon group, a hydrocarbon oxy group, an acyl group, a hydrocarbon oxycarbonyl group, a cyano R'' is a substituent selected from a hydrogen atom or a hydrocarbon group, a hydrocarbon oxy group, a halogen atom, a hydroxyl group and a nitro group) The inventors discovered that the object could be achieved by using a pyridine derivative, and based on this knowledge, the present invention was accomplished.

That is, the present invention provides a display device in which a display electrode and a counter electrode are brought into contact with an electrolytic solution containing an electrochemically reversibly redoxable organic compound, in which pyridine represented by the general formula (11) is used as the organic compound. Image formation in the display device of the present invention is thought to be carried out according to the following reaction00 (R and R″ in the formula have the same meanings as above) In other words, when a negative voltage is applied to the display electrode, the colorless pyridinium cations present in the electrolyte are reduced to radicals (IV), which develops color.
* Once generated, the radical takes on an enol type structure due to the tautomerism shown below, which becomes extremely stabilized due to resonance and at the same time begins to exhibit a yellow or red color〇 (R in the formula
and w have the same meanings as above) These radicals are
Unlike the case of viologen compounds, it does not produce two-electron reduction products and can provide a long-life display device. The compound of the general formula (111) isomerized to the enol form even by the action of an alkali. It has the property of developing color.

Therefore, the display device of the present invention can be configured in such a manner that the hydrogen ions in the electrolyte are reduced before the display material is reduced, and the area near the electrodes becomes alkaline, thereby producing color. Examples of the compound of the general formula (self) that can be used include N-benzoylmethylpyridinium bromide, which has no nuclear substituent at all, and N-benzoylmethyl-2-methylpyridinium, which has a substituent on the pyridine ring or benzene ring. Bromide, N-benzoylmethyl-4
-Ethylpyridinium bromide, N-benzoylmethyl-4-benzylpyridinium bromide, N-benzoylmethyl-4-methoxypyridinium bromide, N-benzoylmethyl-4-benzoylpyridinium bromide N
-benzoylmethyl-3-benzoylpyridinium bromide N-benzoylmethyl-4-methoxycarbonylpyridinium bromide, N-benzoylmethyl-3-hexyloxycarbonylpyridinium bromide N-benzoylmethyl-4-cyanopyridinium bromide
N-benzoylmethyl-3-aminocarbonylpyridinium bromide, N-(45-chlorobenzoylmethyl)
-4-Benzoylpyridinium bromide, N-(4'-phenylbenzoylmethyl)-4-cyanopyridinium bromide, N-(4'-chlorobenzoylmethyl)-4
-aminocarbonylpyridinium bromide, N-(4'
-methylbenzoylmethyl)-pyridinium bromide,
N-(4'-propoxybenzoylmethyl)-pyridinium bromide, N-(4'-hydroxybenzoylmethyl)-pyridinium bromide, N-(4'-nitrobenzoylmethyl)-pyridinium bromide, etc. Examples of supporting electrolytes used in combination with these pyridine derivatives include potassium bromide, cerium bromide, potassium chloride, and lithium chloride.

These pyridine derivatives and the supporting electrolyte are mixed in water or in an aqueous solution buffered with acids or salts at a concentration of 0 for the pyridine derivatives.
．． The supporting electrolyte is dissolved at a concentration of 0.5 mol and the supporting electrolyte is dissolved at a concentration of 0.1 mol and used as an electrolytic solution.Next, an example of the display device of the present invention will be explained according to the attached drawings.The drawing shows the main parts of the display device. This is a schematic cross-sectional view, in which an electrolytic solution 1 containing a pyridine derivative represented by the general formula (I) and a supporting electrolyte is filled in a glass or plastic case 5,
A display electrode 2 and a counter electrode 3 are immersed in this.

Lead wires 4, 4 are attached to these electrodes with conductive adhesive.A transparent plate 6 made of glass or plastic is provided on the front of the case 5, and the display electrode 2 is attached from the outside.
07, which can be seen through, is a hermetic seal. Examples of the display electrode include platinum, gold, silver, nickel, tin oxide, indium oxide, etc., and counter electrodes include platinum, gold, silver, nickel, silver-silver halide, carbon, tin oxide, indium oxide, etc. Used: In such a display device, when a voltage is applied with the display electrode as a cathode and the counter electrode as an anode, a yellow or red image appears on the display electrode. Then, the image completely disappears. The display device of the present invention is a type of passive display, and has the advantages of suppressing eye fatigue, wide viewing angle, and good contrast. Since it consumes less power and has a memory function, it can be used for displays such as watches, desk calendars, and other panels instead of light emitting diodes and liquid crystals. Example 1 In a cell with the structure shown in the attached drawing, potassium bromide (0.1 mO
1e/2) and N-benzoylmethyl-4-benzoylpyridinium bromide (0.05m01e/l) was filled with deoxygenated water to make a display device. In this display device, a voltage of 1 When .5V was applied, a red image was formed on the display pole.Next, when the polarity was reversed and the same voltage was applied, the red image disappeared.
This operation was repeated 104 times and the reproducibility was good. Example 2 In place of N-benzoylmethyl-4-benzoylpyridinium bromide in Example 1, the same amount of N-benzoylmethyl-3-cyanopyridinium was used. A display device was made using Promid in the same manner as above.

In this display device, a voltage of 1.5
When applied, a yellow image was formed at the display pole.

Example 3 An electrolytic solution prepared using the same amount of N-benzoylmethyl-4-methoxycarbonylpyridinium bromide in place of N-benzoylmethyl-4-benzoylpyridinium bromide in Example 1 was impregnated into a polyacrylamide gel. A display device was fabricated by filling the cell shown in the attached drawing with the platinum electrode and using the platinum electrode as a display electrode and a counter electrode. In this display device, when a voltage of 1.5 V was applied using the display electrode as a cathode, a yellow image appeared on the display electrode. Been formed.

Example 4 Display devices using various pyridinium compounds as display materials were manufactured in the same manner as in Example 1, and when a voltage was applied thereto, colored images with the tones shown in the following table were formed. When I reversed the voltage and applied the same voltage, the colored image completely disappeared〇

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view showing essential parts of an example of the device of the present invention, in which reference numeral 1 indicates an electrolytic solution, 2 indicates a display electrode, and 3 indicates a counter electrode.

Claims (1)

[Scope of Claims] 1. A display device in which a display electrode and a counter electrode are brought into contact with an electrolytic solution containing an electrochemically reversibly redoxable organic compound, wherein the organic compound has a general formula ▲ mathematical formula, chemical formula,
There are tables, etc. ▼ (In the formula, ¥R¥ is a hydrogen atom or a substituent selected from a hydrocarbon group, a hydrocarbonoxy group, an acyl group, a hydrocarbonoxycarbonyl group, a cyano group, and an amide group, R' is a hydrogen atom or a substituent selected from a hydrocarbon group, a hydrocarbon oxy group, a halogen atom, a hydroxyl group, and a nitro group)
An electrical display device characterized by using a pyridine derivative represented by: