JP2000091083A - Organic el display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL display having high quality of display, a large area and low power consumption. SOLUTION: This organic EL display 10 is formed by laminating a stripe positive electrode wiring part 12, an organic layer 13 having at least a layer made of an organic light emitting material, and a negative electrode 14 on a transparent board 11 in this order to from a state of plural organic EL elements disposed. The positive electrode wiring part 12 is formed with a translucent part 12a made of the transparent conductive material 12A, and formed with a non-light-emitting area 12b having the metal material 12B having 2×10-5 Ωcm or less of electrical resistivity in parts except for the translucent part 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL (organic electroluminescence) display having an organic EL element provided with an organic light emitting layer.

[0002]

2. Description of the Related Art In recent years, the need for self-luminous flat panel displays has been increasing, and various display devices have been actively developed. In particular, the development of a liquid crystal display (LCD), a plasma display (PDP), an organic EL display, etc. has been vigorously pursued. Among them, a self-luminous type which is capable of high-definition display is an organic EL display. Display has attracted attention, and its research and development has been actively pursued.

[0003] Organic EL is described in the document "Appl. Phys. Lett. 51, 91".
3 (1987) ".
TO) / organic hole transport layer / organic light emitting layer / cathode has a device structure of C.I. W. 1987 by Tang et al.
Research and development has become more widespread following the proposals made in the year.

In general, in an XY matrix type organic EL display, as shown in FIG. 8, a stripe-shaped anode wiring portion 2 serving as a data line is formed on the surface of a transparent substrate 1 made of glass or the like, and holes are formed thereon. An organic layer 3 composed of a transport layer, an organic phosphor layer (organic light emitting layer), etc. is formed in a stripe shape, and a stripe-shaped cathode wiring portion 4 composed of a metal or the like is further formed thereon. It is. The anode wiring portions 2 and the cathode wiring portions 4 are arranged orthogonal to each other, and an organic EL element is formed at the intersection. Since the organic layers 3 are usually patterned using the same mask as the cathode wiring portions 4, they are formed in the same plan view shape as the cathode wiring portions 4.

As shown in FIG. 9, the anode wiring portions 2 are made of the same transparent conductive material in both the light emitting area (light transmitting section) and the non-light emitting area, and are therefore formed in a simple stripe repetition pattern. It has become. That is, the data line is formed integrally with the transparent electrode portion that normally functions as an anode. In addition,
A protective film (not shown) made of an insulating material or the like is usually formed on the cathode wiring portions 4 to prevent the organic layer 3 from deteriorating.

By the way, in such a matrix type organic EL display, as described above, since the data lines (anode wiring portions 2...) Are formed while including the transparent electrode portion functioning as the anode, the organic EL display is used. If, for example, indium tin oxide (ITO) is used as a transparent electrode (anode) for extracting light emission, a data line, that is, a portion of a non-light emitting area is naturally formed of this ITO. However, ITO, which has a low resistance as a transparent conductive material, also has an electrical resistivity of about 1 × 10 ⁻⁴ Ωcm, and has an electrical resistivity of 1 to 2 as compared with a normal metal material.
It is an order of magnitude higher.

[0007]

However, in an organic EL display which is a current-driven device driven by using a large current, if a wiring (data line) is formed of a material having a high electric resistance, the wiring resistance and the wiring resistance are reduced. A potential drop corresponding to the product of the current occurs, and a large voltage is applied to the wiring itself. As a result, an effective voltage is not applied to the organic EL itself, which results in a loss of power consumption.

For example, one pixel is 100 inches at a diagonal of 20 inches.
Assuming a high-resolution organic EL display of μm × 300 μm, if the data line is made of only ITO, the wiring resistance per data line is 100 μm for the data line, 150 nm for the film thickness, and 3 for the stripe length.
Assuming 0 cm, it is 2 × 10 ⁴ Ω. The thickness is set to 150 nm because it cannot be made too thick in consideration of the light transmittance.

Further, if a current having a current density of 1 A / cm ² is supplied to one pixel in order to illuminate the organic EL display with high luminance, a current of 3 × 10 ^-4 A per data line is required. At this time, the voltage drop at the center of the screen is estimated to be 3 V from the equation: V (voltage drop) = I (current flowing through wiring) × R (wiring resistance). When the estimation is performed for all data lines, the power loss due to the wiring resistance of the entire screen at the time of the all white peak reaches several W. Since all of the electric power is converted to heat, an organic EL display having low heat resistance is extremely disadvantageous in terms of its life and reliability.

[0010] In recent years, flat panel displays have been actively developed especially in the direction of larger screens, and organic EL displays are also expected to be larger. However,
When the screen is enlarged, the wiring resistance of a data line or a scanning line increases for the above-mentioned reason, and an increase in power consumption cannot be avoided.

Further, when each pixel is driven by voltage,
At a pixel farther from the driver (power supply), a display quality defect called shading occurs, in which the display becomes darker than a pixel at a shorter distance. This is not the case when the current driving is performed, but in that case, another problem occurs in that the driver circuit becomes complicated and the cost is increased. Note that the problem of increase in power consumption when a high-resistance wiring material is used similarly occurs in both voltage driving and current driving.

In recent years, with the increase in density and diversification of information, there has been a demand for an organic EL display having low power loss, high definition, and high display quality such as multicolor (full color). However, conventionally, the wiring resistance on the anode side has not been reduced, and the wiring (data line) is directly formed of a transparent electrode material having a high electric resistance. The situation was difficult. That is, the problem of increased power consumption is a major barrier to realizing a large-screen display.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an organic EL display having a high display quality, a large area, and low power consumption.

[0014]

According to the organic EL display of the present invention, a stripe-shaped anode wiring portion, an organic layer having at least a layer made of an organic luminescent material, and a cathode are formed in this order on a transparent substrate. The anode wiring portion is formed of a transparent conductive material at least in a portion to be a light-transmitting portion, and a portion of a non-light-emitting area other than the light-transmitting portion is an electric resistivity. 2 × 10 ^-5
The solution to the above problem is to have a metal material of Ωcm or less.

According to this method of manufacturing an organic EL display, the light-transmitting portion of the anode wiring portion is formed of a transparent conductive material, and the non-light-emitting area, which is not the light-transmitting portion, has an electric resistivity of 2 × 10 ^−5. Since it is formed of a metal material of Ωcm or less, the wiring resistance on the anode side is greatly reduced as compared with the conventional case where the entire anode wiring portion is formed of a transparent conductive material.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an organic EL display of the present invention will be described in detail. FIGS. 1A and 1B are views showing an RGB type full-color XY matrix type organic EL display according to an embodiment of the organic EL display of the present invention. In FIG. 1A, reference numeral 10 denotes XY. It is a matrix type organic EL display. FIG.
FIG. 2B is a plan view as seen in the direction of the arrow BB in FIG.

In this organic EL display 10, a stripe-shaped anode wiring portion 12 serving as a data line is formed on the surface of a transparent substrate 11 made of transparent glass, and a hole transport layer and an organic phosphor layer (organic phosphor layer) are formed thereon. A stripe-shaped organic layer 13 composed of a light-emitting layer) is formed, and a stripe-shaped cathode wiring portion (cathode) serving as a scanning line is formed thereon.
.. Are formed. The anode wiring sections 12 and the cathode wiring sections 14 are arranged orthogonally to each other to form an XY matrix. Under such a configuration, the anode wiring sections 12 and the cathode wiring sections 14 are formed. At the intersection of the anode (anode wiring section 12) and the organic layer 1
3. An organic EL element including a cathode (cathode wiring section 14) is formed.

The anode wiring portion 12 is composed of a transparent conductive material portion 12A formed in a stripe shape in this example and a metal material portion 12B covering a predetermined position of the transparent conductive material portion 12A. As shown in FIG. 1B, a hybrid including a light-transmitting portion (light-emitting area) 12a that transmits light emitted from the organic layer 13 in the organic EL element and a non-light-emitting area (non-light-transmitting portion) 12b that is not a light-transmitting portion. The wiring method of the mold is adopted. The light transmitting portion 12a functions as an anode in the organic EL element, and the organic layer 1 is formed by opening the metal material portion 12B as described later.
3. This translucent part 12
a is indium tin oxide (ITO) or tin oxide (Sn
O ₂ ), zinc oxide (ZnO), and other highly conductive transparent conductive materials. In this example, the conductive material is made of indium tin oxide.

On the other hand, in this embodiment, the non-light emitting area 12b is formed by covering the transparent conductive material portion 12A with the metal material portion 12B at a portion other than the light transmitting portion 12a, that is, at the non-light transmitting portion. Therefore, the transparent conductive material portion 1
This is formed by a laminated structure of 2A and metal material portion 12B. As the metal material forming the metal material portion 12B, a material having a low resistivity of 2 × 10 ⁻⁵ Ωcm or less as shown in Table 1 is preferably used. In this example, Al, which is an inexpensive and relatively low-resistance material, is used. Further, even if a metal material other than these, or an alloy composed of a plurality of these metals, or a multilayer film formed by laminating these metals is used, as long as it has a low resistivity of 2 × 10 ⁻⁵ Ωcm or less, the present invention Can be used.

[Table 1]

The organic layers 13 are composed of a red organic layer emitting red light, a green organic layer emitting green light, and a blue organic layer emitting blue light arranged in the same repetition order. . The organic layer of each color is formed on the anode wiring section 12.
On the light-transmitting portion 12a and in contact with the light-transmitting portion 12a. Regarding the organic layers 13, there is no particular limitation on the type, configuration, film thickness, dye doping form, and the like of the materials. For example, the organic layer 13 that emits green light has a two-layer structure in which TPD, α-NPD, or the like is formed as a hole transport layer, and Alq3 or the like is formed as an electron transport layer and a light emitting layer. It is not limited to this. Also, depending on the emission color, Alq
3 is used after being doped with an appropriate dye.

The cathode wiring portions 14 are generally formed of Al, and in this embodiment, also formed of Al. In addition, as a material for forming the cathode wiring portions 14..., For example, a material in which Al is doped with Li by an appropriate method, an alloy containing a group IIa alkaline earth metal of the periodic table such as an Mg-Ag alloy, or the like. Can also be used. All of these are materials having a low work function and have an effect of lowering the threshold voltage of light emission. A protective film (not shown) made of an insulating material or the like is formed on the cathode wiring portions 14 to prevent the organic layers 13 from deteriorating.

The organic EL display 1 having such a configuration
In order to manufacture the transparent substrate 11, first, as shown in FIG. 2A, a transparent (ie, transparent) transparent substrate 11 made of glass or the like is prepared, and a transparent conductive material layer (shown in FIG. (Abbreviation). Then, this transparent conductive material layer is patterned into a stripe shape, that is, a data line pattern shape in an XY matrix type display, and a plurality of transparent conductive material portions 12A are formed in parallel. Here, as a method of forming the transparent conductive material layer, DC
And RF magnetron sputtering method is common,
A CVD method, a reactive vacuum evaporation method, or the like can also be employed. Further, the method of patterning the transparent conductive material layer is not particularly limited, and any of a dry etching method and a wet etching method can be adopted.

Next, a low-resistance metal layer made of Al is formed on the transparent substrate 11 so as to cover the transparent conductive material portions 12A... A hybrid wiring system comprising a light transmitting portion 12a and a non-light emitting area 12b is formed by patterning the opening and exposing the transparent conductive material portion 12A so as to expose the transparent conductive material portion 12A as shown in FIG. 2B. Are obtained. The method of patterning the low-resistance metal layer is not particularly limited, but it is possible to prevent disconnection of the cathode wiring portions 14 formed on the obtained metal material portion 12B and to prevent the cathode wiring portions 14 and the anode wiring portion 12 from being disconnected. To prevent short circuit
Al (metal material portion 1) around light transmitting portion (light emitting area) 12a
2B), it is desirable to etch in a tapered shape so that the width of the anode wiring portion 12 increases from the top to the bottom.

Next, a light emitting material layer (not shown) composed of a laminated film (not shown) such as an organic hole transport film (not shown) and an organic phosphor film (not shown) is formed and patterned. (Red), G (Green), and B (Blue) are sequentially performed, and the organic layer 1 that emits red light as shown in FIG.
3, the organic layer 13 for emitting green light and the organic layer 13 for emitting blue light are each provided in a predetermined pattern,
It is formed in a pattern along the length direction thereof on the upper side and in contact with the transparent conductive material portion 12A on the light transmitting portion 12a.

As described above, the type, structure, film thickness, dye doping form, etc. of the material of the organic layer 13 are not particularly limited. When a light emitting material is used, a vacuum evaporation method is usually employed. Therefore, in order to form three types of organic layers of red, green, and blue in order to make the display panel multi-colored, a specific luminescent material is used only at a predetermined place using a deposition mask during film formation by vacuum deposition. Is formed, and this is repeated a plurality of times (three times) to form RGB patterns respectively.

Next, as shown in FIG. 1A, striped cathode wiring portions 14 orthogonal to the anode wiring portions 12 and the organic layers 13 are formed. This cathode wiring section 14 ...
The wiring pattern of the cathode wiring portions 14
This is performed so as to be used as a scanning line of the Y matrix. As a method for forming the cathode wiring portions 14, a vacuum deposition method for forming a pattern using a mask is suitably adopted, but a sputtering method or the like can also be used.

After that, in order to protect the organic layers 13 from being exposed to oxygen and moisture in the air, for example, a protective film for overcoating is formed by a material capable of forming a film with low damage at a low temperature. Thus, the organic EL display 10 of the present invention is obtained.

The organic EL display 1 having such a configuration
In the case of No. 0, a portion to be the light transmitting portion 12a of the anode wiring portion 12 is formed by the transparent conductive material portion 12A, and the non-light emitting area 12b which is not the light transmitting portion 12a is formed by the transparent conductive material portion 12A and the electric resistivity 2 × 10 2. Since the anode wiring portion is formed of a laminated film with the metal material portion 12B of ^-5 Ωcm or less, the wiring resistance on the anode side can be significantly reduced as compared with the related art in which the entire anode wiring portion is formed of a transparent conductive material.

The effect of reducing the wiring resistance will be described in detail below. FIG. 3 shows a plan view of the anode wiring section 12 per pixel of the organic EL display 10. As shown in FIG. 3, the wiring length per pixel is L, the width of the anode wiring section 12 is W, and the scale factor of the translucent section 12a in the anode wiring section 12 is x (<1) (for convenience, in the width direction). to the the scale factor and the longitudinal direction of the scale factor to the same. Therefore the area of the transmissive portion 12a is ^twice x the area of the anode wiring portion 12) and, estimated as wiring resistance following this time Is done.

The resistivity of the ITO (transparent conductive material portion 12A) and the resistivity of the low-resistance metal material (metal material portion 12B) used for the anode wiring portion 12 are ρ _ITO and ρ _M , respectively.
Then, ρ _M = α · ρ _ITO (where α≪1).
The thickness of the ITO and the thickness of the low-resistance metal are the same. At this time, when the ratio of the wiring resistance R _H per pixel pitch in the anode wiring section 12 to the wiring resistance R _ITO per pixel pitch due to ITO alone is calculated, (R _H / R _ITO ) = α · ｛1 −x + (α · x) / (1−
x + α · x)｝. If the resistivity of ITO is 1 × 10 ⁻⁴ Ωcm and the resistivity of the metal material is 2 × 10 ⁻⁶ Ωcm, α = 0.
02.

As an example showing the effect of reducing the wiring resistance of the anode wiring portion 12 according to the present invention, (R _H / R _ITO )
FIG. 4 shows the dependence of ITO on the scale factor x.
As shown in FIG. 4, when x is set to 90%, the wiring resistance R _H
Is 15.4% of the case of only _ITO (R _ITO ). Further, when reduced to 80%, it becomes 7.4%, and the wiring resistance R
_H will decrease by one digit or more. Therefore, the loss of power consumption is reduced by one digit or more with the reduction of the wiring resistance.

If the value of x is set to a smaller value to further reduce the wiring resistance, as shown in FIG. 4, a large change, that is, a large effect is lost. Therefore, when the value of x is extremely reduced, the light emitting area (the light transmitting portion 1) is rather changed.
The current density in 2a) is increased, which is not preferable because it causes deterioration of the organic EL material. The above is the result of estimation for only the pixel portion. However, if a low-resistance metal material is used for the lead wiring to the driver portion, the resistance can be further reduced.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible for the form of the anode wiring section 12, for example. For example, as a pattern of the anode wiring section, as shown in FIG. 5, the light transmitting section 20a is arranged on one side of the anode wiring section 20, and the opposite side and the space between these light transmitting sections 20a, 20a are covered with the metal material section 20B. The non-light-emitting area 20b may be used.

As shown in FIGS. 6A and 6B,
An island-shaped transparent conductive material portion 2 is formed in advance so that the transparent conductive material is islanded so as to remain only in the light emitting area instead of the stripe shape.
1A are formed in an array, and these transparent conductive material portions 21A, 21A
A and the metal material portion 21B
To form the anode wiring portion 21.

If a metal material having high heat resistance is used as the material for forming the metal material portion, FIG.
As shown in (b), this material is formed on the transparent substrate 11 and subsequently patterned to form a metal material portion 22B made of a low-resistance metal having a window (opening) in a pixel light emitting area (light transmitting portion). Then, a transparent conductive material portion 22A made of ITO or the like may be formed thereon to form the anode wiring portion 22. Also in this case, the transparent conductive material portion 22A may be formed in a stripe shape along the metal material portion 22B serving as a base as shown in FIG.
As shown in (1), an island may be formed by forming an island so as to include only a light emitting area (light transmitting portion).

In the embodiment, the anode wiring section 12
Although the organic layer 13 was formed directly on the anode,
In order to prevent an electrical short circuit between 2) and the cathode (cathode wiring section 14), silicon oxide is preferably applied between the adjacent anode wiring sections 12 while covering the side ends of the anode wiring section 12. things (SiO _x), silicon nitride (Si _x N _y), silicon oxynitride (SiO _x N _y), aluminum oxide (Al _x O _y) has an inorganic inorganic insulating film made of an insulating material such as If you form the inorganic insulating film like this,
High reliability can be obtained by short circuit prevention.

Although the transparent glass is used as the transparent substrate 11 in the above embodiment, the present invention is not limited to the material, thickness and size of the transparent substrate. An organic polymer material such as a film may be used for the transparent substrate. Further, in the above-described embodiment, the full color display having three colors of RGB is particularly provided, but the emission color is not limited to this. As for the patterning method of the organic layer 13 and the cathode wiring section 14, various conventionally known techniques such as a patterning method using a lithography technique and a dry etching technique can be adopted in addition to a method using a mask evaporation.

[0038]

As described above, in the organic EL display of the present invention, the light-transmitting portion of the anode wiring portion is formed of a transparent conductive material, and the non-light-emitting area, which is not the light-transmitting portion, has an electric resistivity of 2%. Since it is formed of a metal material of × 10 ⁻⁵ Ωcm or less, the wiring resistance on the anode side can be greatly reduced as compared with the conventional method in which the entire anode wiring portion is formed of a transparent conductive material. A large area and power saving can be achieved while ensuring excellent display quality.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing an embodiment of an organic EL display according to the present invention, wherein FIG. 1A is a cross-sectional side view of a main part showing a schematic configuration of a light emitting area of the organic EL display; (B) is a plan view as seen in the direction of the arrow BB in (a).

FIGS. 2 (a) to 2 (c) are cross-sectional side views of a main part for describing a method of manufacturing the organic EL display shown in FIG. 1 in the order of steps.

FIG. 3 is a plan view showing an anode wiring portion per pixel of the organic EL display shown in FIG. 1;

FIG. 4 is a graph showing a relationship between (R _H / R _ITO ) and a scale factor x of a light transmitting part.

FIG. 5 is a view showing a modification of the present invention, and is a plan view showing a pattern of an anode wiring portion.

6A and 6B are diagrams showing a modification of the present invention, wherein FIG. 6A is a plan view showing an anode wiring portion per pixel, and FIG. 6B is a side sectional view showing an anode wiring portion per pixel. .

FIGS. 7A and 7B are diagrams showing modified examples of the present invention, and are side sectional views of the anode wiring portion per pixel when viewed in a cross section in the width direction thereof.

FIG. 8 is a sectional side view of a main part showing a schematic configuration of an example of a conventional organic EL display.

FIG. 9 is a plan view showing a pattern of an anode wiring portion in a conventional organic EL display.

[Explanation of symbols]

10 ... organic EL display, 11 ... transparent substrate, 12,
20, 21, 22,... Anode wiring part, 12A, 21A, 22
A: Transparent conductive material part, 12B, 20B, 21B, 22B
... Metal material part, 12a, 20a ... Translucent part, 12b, 20
b: non-light-emitting area, 13: organic layer, 14: cathode wiring section

Continued on the front page (72) Inventor Tetsuo Nakayama 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Mitsunobu Sekiya 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sonny shares In-house (72) Inventor Tatsuya Sasaoka 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 3K007 AB00 AB04 AB05 BA06 CA01 CA06 CB01 DA00 DB03 EB00 FA01 5C094 AA02 AA14 AA22 BA27 CA19 EA05 EB02 FB01

Claims (3)

[Claims] 1. A state in which a stripe-shaped anode wiring portion, an organic layer having at least a layer made of an organic light emitting material, and a cathode are formed in this order on a transparent substrate, and a plurality of organic EL elements are arranged. In the anode wiring portion, at least a portion that becomes a light-transmitting portion is made of a transparent conductive material, and a non-light-emitting area portion that is not a light-transmitting portion has a metal material having an electric resistivity of 2 × 10 ⁻⁵ Ωcm or less. An organic EL display, comprising: 2. The method according to claim 1, wherein the metal material is Ag, Al, Cu, A
2. The semiconductor device according to claim 1, wherein the material is at least one of u, Ni, Co, Fe, Mo, Nb, Pd, and Pt.
The organic EL display according to the above. 3. The organic EL display according to claim 1, wherein a Cr oxide film is provided on a part of a base of a non-light-emitting area in said anode wiring portion.