JPS60181732A - Electrochromic display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (1) Technical field of the invention TECHNICAL FIELD The present invention relates to an electronic ltcochrominok display device.

In particular, the elect 1 cochromink device (hereinafter referred to as ECD)
The present invention relates to an electrochromic display device in which thin film diodes are stacked to enable matrix drive.

('f) Background of the technology It is known that nonlinearity is observed in the voltage-current characteristics when a voltage is applied between two conductor electrodes sandwiching an insulating thin film, and such thin film diodes is explained from the perspective of the tunnel effect. Specifically, as shown in the side view of Figure 1 (ta+) and the plan view of Figure 1 (fb), a first aluminum (Aβ) film 2 is vacuum-deposited on a substrate 1 such as glass, and Alternatively, for example, aluminum oxide (Aj!203)lIQ3 is formed by surface oxidation in oxygen (02), and a second Δl film 4 is deposited on the n203 film to produce an element. The current that flows when a voltage is applied between A7 and 11 exhibits nonlinearity, and a thin film diode 5 can be formed. Thin film diodes using amorphous silicon, selenium (Se), etc. are also known.

Furthermore, regarding the Elec 1-1 Kokurominoku display device, 13
ECD was proposed by S, K, and Deb a year ago. ECD utilizes the electrochromic phenomenon (abbreviated as EC), which is a phenomenon in which color and light transmittance change reversibly due to oxidation and reduction reactions that occur at or near the electrode surface when a voltage is applied to the material. It is a display element. The Deb EC material mentioned above is tungsten oxide (WO3).
) is proposed. IE using WO3
Three types of CDs have been proposed, as shown in the side sectional views shown in Figures 2 (a), (b), and (C1).

If the ECD 7 is of an electrolytic solution type in FIG. 2, transparent electrodes 9. A counter electrode 10 is vapor-deposited, and an E made of WO3 is deposited on the transparent electrode 9.
A C film 13 is formed, and a sealing member 11 is interposed between the transparent electrode 9 and the counter electrode 10.

The area surrounded by the sealing member, the transparent electrode, and the opposing critical state is filled with an electrolytic solution 12.

Figure 2 (The one shown in bl is called a solid electrolyte type ECD, and the electrolyte 12 shown in Figure 2 (8) is a solid type)
vinegar? The id is changed to quality 14, and heta-type aluminum oxide (β-Ati 2.o 3 ) or the like is used. In this configuration, the seal member 11 is omitted.

The one shown in FIG. 2fc) is a dielectric film type ECD.

What is involved in the coloring reaction in ECD is adsorbed moisture in the dielectric film 15 or in the EC film 13 of WO3.As a dielectric abrasive material, silicon oxide (Sin) and silicon oxide (Zr) are used.
O2), tantalum oxide (Ta205), chromium oxide (C
r203), etc. (are obsolete.Furthermore, these dielectrics are sandwiched between n-type WOx and I]-type Irox3).
Elements with layered structures have also been proposed and have obtained good characteristics.

All of the above mentioned 0ECDs are also in contact with the EC film 13.

When a voltage is applied between the opposing electrodes 10 with the transparent electrode 9 at a negative potential, the EC film 13 is colored blue if it is WO3, depending on the amount of charge that flows. This coloring mechanism causes an electrochemical reaction in the WO3 film to produce the following reaction. When a negative potential is applied to the transparent electrode 9, electrons are transferred from the transparent electrode 9 into the WO3 EC film 13 from the interface with the electrolyte. Positive/ion (M”: H
", L i ", etc.) is injected into the liquid to produce color.

WO3-1-(H" 4- e -) x; koHxW
O3 Transparent Blue (3) Problems with the Prior Art The thin film diode described above does not have memory properties, making it impossible to obtain a switching element with memory properties.

Regarding ECD, the threshold value is unclear and the response speed is slow.

Due to problems such as a lack of short memory, the ECD cannot be simply driven in matrix.

(4) Purpose of the Invention In view of the drawbacks of the conventional art, the present invention provides an electronic device that can perform matrix drive and address in a short address time by laminating thin film diodes that can be used as switching elements with memory properties on an ECD. It is an object of the present invention to provide a one-kokuromisoku display device.

(5) Structure and the above object of the invention is to form a Schottky barrier on at least one interface of a transitional total bending oxide semiconductor thin film sandwiched between two electrodes, and to An electrochromic display device characterized by stacking electrochromic display elements and a transition metal oxide semiconductor thin film sandwiched between two electrodes.
This is achieved by providing an electromink display device characterized by laminating an electrochromic display element on a thin film diode in which an n-junction is formed.

(6) Examples of the invention The following 1. 17. of the invention. An example of a thin film diode laminated with a CD will be described in detail with reference to the drawings.

FIG. 3 is a perspective view showing the structure of the thin film diode of the present invention.

In FIG. 3, ζL does not indicate a thin film diode, and 16 is a glass substrate similar to that in FIG. 1, on which titanium (Ti) is deposited as a lower electrode 17.

The transition metal oxide semiconductor thin film 18 is formed by RF reactive magnetron sputtering (RF reactive magnetron sputtering).
Set the atmosphere of the agnetron 5put ring to 02 (3X10-', Torr), use tungsten W (10cmφ) for the cuget, and set the distance A to the substrate 16.
Tungsten oxide (WOx) was formed by setting ll to 5 cm and RF power to 100 OW (x≦3).

Furthermore, an upper electrode 19 was formed by depositing iridium (Ir) on the transition metal oxide semiconductor thin film 18.

The thickness of the transition metal oxide semiconductor thin film 18 is 700 mm.
0 people, active area is 0.01 cJ.

The thin film diode 1 constructed as described above exhibits non-linearity in voltage-current characteristics as shown in FIG. 4, similar to that shown in FIG. That is, in Fig. 4, the voltage (V) is the voltage applied to the upper electrode 19 side, and the current (m^) flowing between the upper and lower electrodes 17 and 19 has very good rectification as shown by curve 20 in the figure. show.

In the above example, WOX (x≦3) was used as the oxide for the transition metal oxide semiconductor thin film.

Molybdenum oxide (M o Ox ) (
X≦3), vanadium oxide (V2O (X≦5), and a mixture thereof at a gas pressure of 3×10”2 Torr・5
Sputtering may be performed with a power greater than W/cut.

Furthermore, although Ir was used for the upper electrode 19, platinum (PL>) and palladium (Pd) were used instead.

Tungsten (W), tantalum (Ta), tin oxide (Sn)
Metals and metal oxides such as O2), indium tin oxide (In202:Sn), etc. can be selected.

The transition metal oxide semiconductor thin film 18 such as WOX mentioned above is n
The upper electrode 19 is made of type semiconductor material and has a larger work function.
If this is selected, the junction surface will form a Schottky barrier, and a thin film diode exhibiting the rectifying characteristics shown in FIG. 4 will be obtained.

When aging is performed by applying a triangular wave voltage of approximately ±2.7 V several times between the upper and lower electrodes 17 and 19 of a thin film diode 1''5 configured as a double series, the result is shown in FIG. 5(a).

An N-film diode 1'' having hysteresis characteristics as shown in (1) can be obtained.

Figure 5 ta+ shows the current A/cJ on the vertical axis and the voltage on the horizontal axis, and the voltage was measured on the lower electrode 17 side.Contrary to the case in Figure 4, the negative side is the forward direction and the positive side is the reverse direction. It has become. The frequency of the applied triangular wave was 0.0I11z, and FIG. 5 (bl) shows the case where the frequency is 1Kllz under the same conditions as FIG. 5(al).

As shown in curves 21a and 21b in both FIGS. 5(al) and (b), the current begins to flow suddenly when the reverse bias voltage is around 1.6V, and as the voltage increases to about 2.5V, the current is 0.25V.
When a current of A/cJ flows and then the voltage is lowered in the direction of zero, a hysteresis curve 22a is obtained.

22b, the current becomes zero near 1.6V.

When the voltage is further decreased in the negative direction (Figure 5 (++l, (forward direction in bl) When the voltage is increased in the direction of zero, hysteresis curves 23a and 23b are drawn, and the current becomes zero near -1 and 2.

The reason why such a hysteresis curve is formed is that the upper and lower electrodes 17
．． This phenomenon is specified to occur when the thickness of the depletion layer in the film changes due to the movement of ions (protons) in the thin film due to the reverse or forward bias voltage applied between 19 and 19. As a demonstration of this hand model mechanism, as shown in Figure 6, the horizontal axis represents the voltage, and the vertical axis represents the capacitance C.
The capacitance value of the rib when the voltage is lowered from zero in the positive direction, then returned to the zero direction, and further increased in the positive direction and returned to the zero direction is as shown by curve 24 in Figure 6. This corresponds to the expansion and contraction of the depletion layer. That is, a large capacitance means a small depletion layer, and a small capacitance means that the depletion layer has expanded.

The above embodiment has such a hysteresis characteristic;
WOX, V20X as the transitional fully bent oxide semiconductor 'a, llQ sandwiched between the upper and lower electrodes of the W film diode.

Using Mobx or the like, connect Shoso 1 to 1 between the upper electrode 19.
I mentioned the case of forming a key barrier.

A p-type 1rox (x≦3
) by intervening -U, 1゛1-WOx-1rOx-T
Even in the r configuration, as shown in Figure 7, with aging ■-I
Hysteresis 25 can be given to the characteristics.

'N1ox (x≦2) can also be used in place of the above 1r, OX.

An embodiment in which each of the 11+'i thin film diodes described above is used as a switching element having a memory function will be described in detail with reference to FIGS. 8 to 11.

8 and 10 are schematic diagrams showing the structure of the address pulse Va and the readout pulse, and FIGS. 9 and 11 show the relationship between the address voltage and readout current of the thin film diode of the present invention. .

Figure 8 shows that as shown in the hysteresis curve in Figure 5 (al), when a trigger is applied by a forward address pulse 26 (pulse voltage Va, pulse width 500m5), reading is performed with a negative voltage pulse 27 after 10 seconds. The relationship between the read current and the address voltage Va in this case is as shown by curve 28 in FIG. 500m to have hysteresis characteristics as shown in the section.
5 pulse width'? It is possible to read out data up to 10 seconds later using the t address pulse 26, making it possible to obtain a switching means having a memory function.

FIG. 10 shows the forward direction pulse shown in FIG. 5 (11), that is, the address pulse 2G, which triggers the switching trigger 'CJ
J) This is the case where the read pulse 27a is performed at a positive voltage, and the current rises rapidly from around -2V as shown by a curve 29 in FIG.

The above switching is stored in the thin film diode Σ for at least several tens of seconds after application of the address pulse. That is, the thin film diode 1'' of the present invention can be used as a switching device 1'!i having a memory function.Furthermore, the thin film diode 1'' can be used to drive a matrix of an electronic device 1'!i. The case will be described in detail in Figure 12 and below.

Figure 12 (ta+, (bl) shows one embodiment of the present invention, and shows a side sectional view of an electrochromic display device in which E CD 7 is laminated on the thin film diode i of the present invention. 30 is a glass substrate on which Ti is sputtered by RF magnetron sputtering to form a lower electrode 31. Furthermore, WOx
is sputtered by RF reactive magnetron sputtering to form a transition metal oxide semiconductor thin film 32, and an upper electrode 33 is formed on the transition metal oxide semiconductor thin film 32.
Similarly to the lower electrode, Ir is sputtered by RF magnet 1 consputtering to form a thin film diode 1, and Irox is further RF-reacted onto the upper electrode 33 in order to stack the ECD 7 on the thin film diode 'Σ. A reduction color-forming EC layer 34 is formed by sputtering with a magnetic magnetron sputtering, and Ta is applied on the reduction color-forming EC layer 34.
A solid electrolyte Y layer 35 such as No. 205 is vacuum deposited, and WO3 is similarly vacuum deposited on the solid electrolyte layer 35 to form an oxidative color-forming EC layer 36. After that, an I n layer 36 is formed on the EC 136 by RF ion plating. A transparent conductive film 37 made of 203 or SnO3 is formed.

In Figure 12 (BL), the materials for the upper and lower electrodes 31 and 33 in the shadow of the thin film diode were selected opposite to those in Figure 12 (al), and Ir was selected for the lower electrode and Ti for the upper electrode. .

When the electrochromic display device shown in FIGS. 12(a) and 12(b) is driven with voltage pulses as shown in FIG. 13(a), 7-socks address driving can be performed.

Examples of the characteristics of the element shown in FIG. 12 (81) are shown below. In FIG.
(expressed as a voltage of 1), V'a is the address voltage,
■o is the ECD coloring voltage, 74 is the address pulse width, τa-15fflS, VC=1■, and the BCD
When the address pulse voltage Va is changed, the speed of the next coloring changes as shown in FIG. 13(b). That is, in the figure, the vertical axis is the optical density and the horizontal axis is the time multiplied by Vc, and a remarkable change is seen between the address pulse Va=-3V and -5V. The case of coloring a negative image and a positive image using this will be described below. V for negative images
A--5V is sequentially applied to the non-selected screen of 7 trix to address the screen.Next, when VC-1,5V is applied to the entire screen, the part to which the pulse is applied is not colored.

Color only the parts that are not applied. In the case of a positive image, Va=-5V is applied to the entire image. Next, a positive address voltage Va' is sequentially applied to the selected pixels to address them. Finally, when a voltage of c-1.5V is applied to the entire area, the parts to which the pulse is applied are colored, and the parts to which no pulse is applied are not colored. That is, matrix addressing can be easily performed.

Furthermore, as can be seen from the voltage-transmittance (6328 people) hysteresis shown in Figure 14 (111, (bl, (C1)).

There is also a phenomenon in which the dark value of color 9 shifts to the high voltage side by increasing the voltage amplitude on the negative side.

Here, the voltage-transmittance hysteresis was measured by applying a 1 fiz triangular wave. By utilizing such a phenomenon, it is possible to select between 1 coloring and no coloring.

Figure 15 fan, (b) is Figure 12+in), (b
) shows a side sectional view of a modified electrochromic display device in which a BCD 7 is first laminated on a glass substrate 30.

A mirror diode l is formed on the top layer.

That is, in FIG. 14 (in al, transparent conductive film 37-oxidation color development E
CWt34-・Fixed electrolyte layer (Ta 20 Q) 35
"Reduction coloring property E' (I Hibiki (WO3, > 36-Lower electrode (Ti) 31-Transition metal oxide semiconductor thin 11Q (JA
r () 3 ) 32-. Upper electrodes (Ir) 33 are sequentially laminated, and in FIG. 15(b), the materials of the upper and lower electrodes 31 and 33 of the thin film diode 5 portion are reversely selected.

FIG. 16 shows the voltage-current characteristics and voltage-transmitted light intensity characteristics of the above configuration.

38b is a curve having a hysteresis characteristic of the thin film diode 5 portion, and the transmitted light intensity curve 3 corresponds to the curve 38b.
As is clear from 9b (wavelength λ - 6328 people), the darkness value for coloring is 2 to 2.4V, which is not shown in Fig. 18, and is not shown in conventional EC.
Voltage-current and voltage-transmitted light intensity characteristic curves 38.
This is a significant improvement compared to 39. In the present invention, the voltage O
It can be seen that up to volts, no decoloring reaction occurs and the short memory function is η-.

FIG. 17(a), (What is not shown in bl shows still another embodiment of the present invention, and the above-mentioned p-n junction type \+V IK' diode n Ii WOX or p
It is configured so that the IroX of 1W is shared with the IECDOEC layer 34.36 (a-based or oxidation color forming), and in FIG. 17 611, the glass substrate 30-/transparent conductive film (
S1102) - One-transition metal oxide semiconductor thin film (WOX)
32-p-type layer and IEC layer of thin film diode (IrOx)
34-Solid electrolyte layer (Ta20r,) 35-EC layer (W
O3) 36-+a Bright conductive film (Sn02) 37 is laminated as shown in FIG.
(T a 20 fi ) 35-p-type layer and ECJii of thin film diode 13 (I r Ox) 34 -> transition metal oxide semiconductor diluted (wox) 32 - transparent conductive film 3
They are laminated in the order of 7.

In each of the above embodiments, if the upper and lower electrodes of the thin film diode are formed in a matrix shape and switching is performed, 10 is/
A large-capacity electrochromic display device can be provided in which the ECD can be switched in a time less than 1.

(7) Effects of the Invention As explained in detail in 2.9, according to the electrochromic display device of the present invention, it is possible to drive the ECD by 7 trinkles, and it is also possible to impart a dark value characteristic, so that coloring can be carried out at 2 to 2.4 ■. Not only is the dark value not unclear as in the conventional case, but it also has a short memory function, making it possible to realize a display device with a fast response speed.

[Brief explanation of drawings]

FIG. 1 (81, (bl) is a side view and plan view of a conventional thin film diode, FIG. 4 is a voltage-current characteristic diagram of the thin film diode shown in FIG. The figure shows the case where the threshold value of the applied triangular wave is 0.0I11z, and the threshold value of the applied triangular wave is 0.0I11z. Characteristic diagram showing the change in capacitance when the voltage is decreased in the positive direction, the voltage is further increased in the positive direction, and the voltage is further decreased in the positive direction, and the voltage is further decreased in the positive direction. The figure is a voltage-current characteristic diagram of a thin film diode according to another embodiment of the present invention, 8th rgJ and 10th rgJ.
The figure is a schematic waveform diagram showing the relationship between an alarm pulse and a readout pulse when an alarm pulse for switching is applied to the thin film diode of the present invention and read out after a predetermined time.
9 and 11 are readout current curve diagrams after application of the address voltage, FIG. is a driving pulse diagram of the 0ECD according to the present invention. Figure 13 fb) is a characteristic diagram showing the relationship between optical density and time after applying the coloring voltage, and Figure 14 (at, (bl,
(cl is voltage-transmittance characteristic diagram, Fig. 15 + al, (
b) and FIG. 17(ill, (bl) is a side cross-sectional view showing another embodiment of the electrochromic display device of the present invention, FIG. 16 is a side sectional view showing the electrochromic display device shown in FIG. Voltage-current and voltage-transmitted light intensity characteristic diagrams of a display device. Fig. 18 is a voltage-current and voltage-transmitted light intensity characteristic diagram of a conventional ECD. 1.8a, 8b, 16.30...Glass Substrate. 2... First A7! film, 3... AI!2o3 film,
4... Second Al film, 5... Thin film diode,
7...ECD. 9...Transparent electrode, 10...Counter electrode. 11... Seal member, 12... Electrolyte. 13...Scream EC removal, 14.35...One solid electrolyte layer,
15...Dielectric film. 17.31...Lower electrode, 18.32...Transition metal oxide semiconductor thin film, 19°33...Upper electrode,
34... Reduction color-forming EC layer, 36... Oxidation color-forming EC layer. 37...Transparent conductive film. Fig. 5 (tilt) tJf-(V) (times) (-〇 room 1L teni (v) 0 History IV Fig. 6 Fig. 7Lχ1 Riq Den/E (Vn Fig. 15 Fig. 16 Gol) 't , 屓V) → #) w117Figure 18Figure 9 Evening shaku (V)

Claims (7)

[Claims] (1) An electronic device comprising an electro-chromic display element stacked on a thin film diode in which a Schottky barrier is formed at at least one interface of a transition metal oxide semiconductor thin film sandwiched between two electrodes. Chromic display device. (2) An electrotorch comprising an electrochromic display element laminated on a thin film diode in which a p-n junction is formed at at least one interface of a transition metal oxide semiconductor thin film sandwiched between two electrodes. 1 comic display device. (3) The electrochromic device according to claim 1 or 2, wherein an electrode at the interface between the thin film diode and the electrochromic display device is omitted. (4) The electrochromic display device according to claim 1, wherein the coloring or decoloring trigger of the electrochromic element is driven by the thin film diode. (5) The electronic/trochromic display device according to claim 2, wherein the coloring or decoloring trigger of the electronic/trochromic element is driven by the thin film diode. (6) The coloring or decoloring trigger of the electrochromic element is driven by a pulse in a reverse bias direction of a Schottky barrier or a p-n junction of the thin film diode.
The electrochromic display device described in . (7) Claim 2, characterized in that the n or 9 layer of the p-11 junction of the AV film DIO-F is also used as a reduction color-forming electrochromic layer or an oxidation color-forming electrochromic layer. The electrochromic display device described.