JPS617380A - Electrochromic display element - Google Patents

Abstract

PURPOSE:The titled element having an electrochromic layer consisting of an anodically colorable specific compound and an electrolytic layer between electrodes and high transmittance, good display quality and wide range of application. CONSTITUTION:An electrochromic display element obtained by providing an anodically colorable electrochromic (abbreviated to EC) layer 3' consisting of at least a compound expressed by the formula and preferably a cathodically colorable EC layer 5 and an electrolytic layer 4 formed from a solid electrolyte thin film between the layers 3' and 5 between a pair of electrodes 1 and 6. The above-mentioned anodically colorable EC layer 3' is preferably formed by applying a higher positive and negative voltages than the ordinary operating voltage alternately to an Ir oxide film prepared by reactive sputtering or reactive ion plating in a solution or element, and reducing the resultant film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrochromic display element.

Electrochromic (EC) devices display information using the reversible color change of substances caused by electrochemical reactions.Therefore, they have the advantage of being independent of viewing angle and making the display easy to see. Another major feature of the oEC table is that it can realize an all-solid-state thin film display. This cannot be imitated by light-receiving liquid crystal displays. It also has a memory function in an open circuit state.

Since the driving voltage is low, active research and development is underway to develop application fields that take advantage of this characteristic.

[Conventional technology]

Conventionally, as an anode colored EC layer of an EC display element,
A method of applying an Ir anodic oxide film and a method of applying an oxidized Irg film produced by reactive sputtering or reactive ion plating are known. The transmittance of the anodic oxide film decreases over time, resulting in poor display quality when it is made into a device.Also, since it is immersed in an aqueous sulfuric acid solution after Ir is deposited, the device configurations that can be applied to it are limited. It will be done. Furthermore, when manufacturing a device with a large screen, it is difficult to ensure film homogeneity. The Ir oxide film produced by reactive sputtering or reactive ion plating has a low transmittance of the film itself, so when it is made into a device, there is a problem of poor display quality. [Problem to be solved by the invention] ] The present invention solves the above-mentioned conventional problems.

[Means for Solving the Problem] The present invention provides an anode-colored EC1iKIrOx (OH
)y (0,5x6F61.5x) is used to construct an EC display element.

[Effect]

Even when the anode-colored EC layer according to the present invention is produced by reactive sputtering or reactive ion plating, an EC display element with high transmittance and good display quality can be obtained.

〔Example〕

Examples of the present invention will be explained below with reference to the drawings. Figure 1 shows the transmittance (
In Figure 0, which shows the spectra in the visible wavelength region of the EC film (reflection mode) in comparison with those of an anodized film and a reactive sputtered film, line A shows the transmittance characteristics of the EC film according to the present invention, and line B shows the transmittance characteristics of the EC film according to the present invention. For the anodic oxide film, line C shows the transmittance characteristics of the reactive sputtered film. 365x, whereas
The gc film A of the present invention has y=”o, y 26 x L O,
Within the range of 5x<y≦1.5x (S).

This EC film A can be produced by reducing an Ir oxide (iridium) film in a solution, but even without the use of a solution, it is possible to produce a positive and negative voltage higher than the operating voltage in an all-solid thin film EC element containing an Ir oxide film. It can be formed by reducing the voltage by alternating the voltage. Therefore, it is possible to form a homogeneous film even on a large-screen device without requiring immersion in an acid solution, making it possible to have a wide range of applications.

It is known that Ir oxide is generally stable in the Ir0t state, and Ir oxide films obtained by reactive Ir ivy or reactive ion plating are also stable in the Ir0t state.
01 is considered to be the main component.

On the other hand, the results of gravimetric analysis show that the Ir anodic oxide film is
H) m is presumed to be the main component O IrOx (OH)7 (0,5xJ-3'61.5x
) is basically considered to have IrO.OH as its main component. This is also supported by the results of the aforementioned XPS analysis. Therefore, when the film of the present invention is formed by reduction treatment of Ir oxide, the changes inside the film are generally expressed by the chemical formula Ire, +H+e −+IrO・OH. However, the chemical formula strictly conforms to the above formula. At least the resulting film is Ir0x(OH)y (0,5X≦y≦1
．． 5x'), the effect of the present invention can be sufficiently produced. An embodiment of the present invention will be explained with reference to FIGS. 2 and 3. FIG. 2 shows an ITO film with a thickness of approximately 200 nm. Layer (transparent electrode) 1
2 is a diagram showing a state in which an Ir oxide film 3 having a thickness of about 100 nrn is formed by reactive sputtering on a glass substrate 2 coated with . The Ir oxide film 3 is 3×10” Torr.
0. This film 3 was formed with 50 W of RF power in an atmosphere.
IrOx was determined by XPSC (X-ray photoelectron spectroscopy) analysis.
The compound was found to be (OH)+11161131. Next, the substrate of the second figure is immersed in a 1N sulfuric acid aqueous solution, and the potential of the substrate is set to -kV (vsSCE) and +
Reduction treatment was performed by alternately shaking 5 times at the same voltage of 2.0 V (vs SCE). The EC layer 3 (see Figure 3) using a platinum plate as the counter electrode was determined by XPS analysis to
It turned out to be a compound called (OH)at2sx.
The manner in which the transmittance of the EC layer 3 increases due to this change is already shown by line A in FIG. Next, on the surface of the EC layer 3 on this substrate, about 250 nm of Ta, O,
A thick solid electrolyte layer 4 and a cathode-colored EC layer 5 of about 250 nm thick made of WOs are each coated with 1xtO-'T.
Formed by EB evaporation method in a vacuum of orr.Furthermore,
On top of that, an ITO layer 6 with a thickness of about 150 nm is placed 3 to 4 times
RF power too in an atmosphere of IO-'Torr
It was formed using the ion plating method.

The thin film EC element in the state shown in FIG.
00ms, color erasure response time (applied voltage IV) 50m5
The transmittance in the decolored state is 500n, which is the maximum visibility.
92% (reflection mode) in the vicinity of An Ir oxide film 3' is formed thereon by reactive sputtering, and then the oxide 1
．． On the membrane 3' is a solid electrolyte N4. The manufacturing conditions for each layer are the same as in the first embodiment described above. A voltage of ±1.8 V is alternately applied between the upper and lower electrodes of this device. By adding K times, the Ir oxide film 3 becomes I rox (Q
H) y (0,5x≦y≦1.5X) ◎This conversion actually occurs in the element as follows:
This can be confirmed by measuring the electrode reaction. 〇 FIG. 5 is a portammogram (current density J-electrical curve) in the IN sulfuric acid aqueous solution in the state shown in FIG. 2 in the first embodiment. At this time, the potential is 10.25 to 1.25V (vs
8CE) was scanned at 338 cycles. The opposite pole is P
At the t electrode, the peak of the EC coloring reaction occurs around 0.6 V after the reduction treatment (solid line) compared to before the @ treatment (dotted line).

On the other hand, FIG. 6 is a portamogram of the device shown in FIG. 3 of the second embodiment. After treatment by applying a voltage of ±1.8V alternately five times (solid line), the amount of reaction increased compared to before treatment (point m), and a peak of 11ilC also occurred around 0.6V. After the treatment, the portamograms in Figures 5 and 6 almost match, indicating that similar electrode reactions are occurring. This means that I rOr (OH)o, 5g5z −+ I
r Ox (OH) 0.7265x) is actually occurring.

As a result of the above treatment, the characteristics of the element shown in Fig. 4 are that the colored density increases from Δ0D=0.3 (applied voltage 1.4 V, 200 m5) to 0.5, and the transmittance in the decolorized state increases from 84 cm to 92 cm.
-increased to -. The increase in color density appears to be due to the disappearance of the barrier as described above. The decoloring response time of the element after treatment was 50 m5 (applied voltage -1, OV).

〔Effect of the invention〕

According to the present invention, a large-screen EC element with high display quality can be obtained by simple means, and its practical effects are remarkable.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the transmittance characteristics of the EC layer according to the present invention, FIGS. 2 and 3 are cross-sectional views showing the EC display element of the first embodiment according to the present invention, and FIG. 4 is a diagram showing the transmittance characteristics of the EC layer according to the present invention. Fi of the second embodiment
C is a cross-sectional view showing the display element, and FIGS. 5 and 6 are views showing portamograms of the first and second embodiments. In the figure, 1 and 6 are transparent electrodes, and I'l'O12 is the substrate. , 3 and 3' are anode-colored EC layers, 4 is an electrolyte layer, and 5 is a cathode-colored EC layer.Figure 2, Figure 3, Figure 4! oj (, utri/V door) f

Claims (5)

[Claims] (1) It has at least an anode-colored electrochromic layer and an electrolyte layer between a pair of electrodes, and the electrochromic layer has IrOx(OH)y (0.5x≦y
1.5x). (2) The electrochromic layer according to claim 1, wherein the electrochromic layer is formed by reducing an Ir oxide film produced by reactive sputtering or reactive ion plating in a solution. Chromic display element. (3) The electrolyte layer is formed of a solid electrolyte thin film, and at least the solid electrolyte thin film, the electrochromic layer, and a cathode-colored electrochromic layer are provided between the electrodes. The electrochromic display element described in . (4) The anode-colored electrochromic layer is formed by reducing an Ir oxide film produced by reactive sputtering or reactive ion plating in a device. The electrochromic display element described in . (5) The electrochromic display element according to claim 4, wherein the reduction treatment is performed by alternately applying positive and negative voltages higher than a normal operating voltage to the element.