KR100342194B1 - Organic electroluminescent device and method for fabricating thereof - Google Patents

Abstract

The present invention relates to an organic electroluminescent device that maximizes mass productivity with low power consumption and high brightness realized at low power consumption. According to the present invention, the organic electroluminescent device is manufactured using high brightness and optical illusion characteristics. There is an effect to greatly improve the mass productivity of the light absorption layer inducing power consumption.

Description

Organic electroluminescent device and method for fabricating

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to organic electroluminescent devices, and more particularly, to organic electroluminescent devices in which mass productivity is maximized with low power consumption and high brightness characteristics at low power consumption.

One of the commonly used display devices, the CRT (Cathode Ray Tube) display device is mainly used in TVs, measuring devices, information terminal devices, etc. In the case of the CRT display device due to its own weight and size, There is a problem in that it cannot actively cope with the demand for downsizing and weight reduction.

In order to replace the CRT display device, a flat panel display device having advantages such as light weight, shortening, and low power consumption is being actively developed, and its demand is continuously increasing.

Until now, the demand for a liquid crystal display device for displaying information by using the electro-optic shutter characteristics of liquid crystals among flat panel display devices has been the highest.

However, the liquid crystal display device is a light-receiving device that displays an image by controlling the amount of external light through the liquid crystal, and since the liquid crystal must be individually controlled, driving is complicated and a separate light source for irradiating light to the liquid crystal panel. In other words, since it requires a "backlight assembly," there are many disadvantages in various aspects, such as light and small size and price competitiveness of the liquid crystal display device.

As a result, organic electroluminescence is an active light emitting device that has a fast response speed, excellent brightness, and a simple structure, which is advantageous in terms of cost competitiveness and can easily realize light and small size reduction, compared to a liquid crystal display device which is a light receiving device. Development of the device is actively progressing.

The organic electroluminescent device is attracting attention as a next-generation flat panel display to replace the liquid crystal display device because of its various uses such as a backlight of the liquid crystal display device, a portable terminal, a car navigation system, a wall-mounted TV.

Such an organic electroluminescent device is interposed between an anode electrode to which positive power is applied and a cathode electrode, a cathode electrode, and an anode electrode to which negative power is applied, and holes transmitted from the anode electrode and electrons transmitted from the cathode electrode are recombined to have a predetermined color. It can be defined as a collection of unit organic electroluminescent devices composed of an organic electroluminescent layer made of an organic electroluminescent material that emits light.

At this time, the light generated in the organic electroluminescent layer of the unit organic electroluminescent device is driven to generate one of the three primary colors of light, red, green, and blue, and the light quantity of the unit organic electroluminescent device, that is, the unit organic electroluminescent device. Full-color display is also possible by controlling the applied power.

However, an organic electroluminescent device displaying a desired image as an aggregate of such unit organic electroluminescent devices has a particularly weak point in deteriorating display performance by an external light source.

Specifically, light generated from an external light source of a unit organic electroluminescent device, for example, a natural artificial light source such as a solar light source or a fluorescent lamp, passes through an anode electrode, passes through an organic electroluminescent layer, and then has a high reflectance such as aluminum. Reflected to the cathode electrode made of a material of and is incident to the eyes of the user through the organic electroluminescent layer and the anode electrode.

Due to this series of mechanisms, both the light reflected from the cathode electrode and the organic electroluminescent layer are artificially incident on the user's eye, and thus the light for the display is incident. In other words, the contrast ratio becomes less than 8: 1, which is the minimum luminance ratio for clearly distinguishing an image, so that the display proceeds normally in a dark place where the illuminance of the external light source is very low, and the illuminance of the external light source is the standard illuminance, that is, 500 lux. Above (LUX), there is a problem that the display performance is significantly reduced.

Recently, various methods have been developed to overcome this problem. As a representative method, a circular polarizing plate is attached to the outside of the anode electrode so that an external light source is reflected on the cathode electrode once it is incident inside the anode electrode. There is a way to prevent it from going outside.

However, when the circularly polarizing plate is used, the light generated in the organic electroluminescent layer also passes through the circularly polarizing plate and generates about 50% light loss like the external light source, so that the luminance ratio of the entire display screen is satisfied, but the screen is dark overall. Has a visible problem.

This problem is overcome by again brightening the intensity of light generated in the organic electroluminescent layer by about 2 times to satisfy both high brightness and screen brightness.

However, in order to satisfy both the high brightness characteristic and the screen brightness characteristic in the related art organic electroluminescent device, another problem arises in that power consumption is greatly increased by applying more power to the unit organic electroluminescent element.

In addition, the lifespan of the organic electroluminescent layer is inversely proportional to the size of the applied power, that is, the life of the organic electroluminescent layer is shortened as a high current is applied, so that the lifetime of the organic electroluminescent device is shortened instead of satisfying the high luminance and screen brightness characteristics. Have

In addition, in view of the fact that the organic electroluminescent device is mainly used as a portable device, when the power consumption required for the display is excessively increased, the recharging time is shortened, causing inconvenience to the user.

Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to provide an organic electroluminescent device with low power consumption while satisfying both high brightness and screen brightness characteristics.

In addition, another object of the present invention is to ensure that the organic electroluminescent device does not shorten the life while satisfying both high brightness characteristics, screen brightness characteristics, and low power consumption characteristics.

Yet another object of the present invention is to ensure that the recharging time of the power source for displaying the organic electroluminescent device is not shortened.

Further, another object of the present invention is to improve the productivity of the means necessary to implement the object of the present invention described above to increase the productivity.

Still other objects of the present invention will become more apparent from the detailed description of the invention which will be described later in detail.

1A-1M are process diagrams showing one embodiment of an organic electroluminescent device according to the present invention.

2A to 2L are process diagrams showing another embodiment of the organic electroluminescent device according to the present invention.

3 is a conceptual diagram showing another embodiment of the present invention.

4 is a plan view of a pattern mask showing a pattern of a pattern mask for forming a light absorption layer according to the present invention.

The organic electroluminescent device according to the present invention for realizing the object of the present invention comprises an anode electrode plate formed of at least one piece so as not to be short-circuited to one side of the substrate, through which the light is transmitted, and the anode electrode plate External light absorbing means comprising a light absorbing thin film layer composed of at least one layer so as to be insulated from one surface, and a light emitting opening formed by opening a portion of the light absorbing thin film layer corresponding to the upper surface of the anode electrode plate in a predetermined shape; And an organic electroluminescent layer formed in the light emitting opening and contacting the anode electrode, and a cathode electrode formed on the organic electroluminescent layer and intersecting the anode electrode.

Hereinafter, embodiments of the organic electroluminescent device and the method for manufacturing the organic electroluminescent device according to the present invention will be described with reference to the accompanying drawings.

<Example 1>

1A to 1M show a method of manufacturing an organic electroluminescent device according to the present invention, and FIG. 1M shows an organic electroluminescent device according to the present invention.

The manufacturing method of the organic electroluminescent device by this invention is as follows.

1A to 1C, a light absorbing layer 20 having both low power consumption and brightness characteristics is formed on one side of the transparent substrate 10, preferably, the glass substrate having high transparency. .

Specifically, the light absorption layer 20 is composed of at least two thin film layers.

More specifically, as shown in FIG. 1A, the light absorption layer 20 is a non-conductive chromium oxide thin film layer 22 formed to have a predetermined thickness on the upper surface of the transparent substrate 10, as shown in FIG. 1B. The conductive chromium thin film layer 24 formed on the upper surface of the chromium oxide thin film layer 22 as shown in FIG. 1C and the non-conductive chromium oxide thin film layer 26 formed on the upper surface of the chromium thin film layer 24 as shown in FIG. 1C.

The light absorption layer 20 is such that the light absorption by the non-conductive chromium oxide thin film layer 22, the chromium oxide thin film layer 24, the chromium oxide thin film layer 26 is close to 100% in order to reduce the reflectance of light incident from the outside. It does not reflect to the user's eyes and plays a role of high brightness.

In this case, in order to display an image having a resolution of 1024 × 768 on the light absorbing layer 20 formed on the transparent substrate 10, for example, 1024 × 768 × 3 in matrix form on the transparent substrate 10 is displayed. There is a need for a corresponding number of unit organic electroluminescent devices.

As the number of formation of the unit organic electroluminescent elements according to the resolution is determined as described above, the formation positions such as spacing, size, etc. between the organic electroluminescent elements to be formed are also tentatively determined.

As such, when the formation position of the organic electroluminescent device is tentatively determined, as shown in FIGS. 1C and 1D, the organic electroluminescent device is formed in the light absorbing layer 20 formed on the transparent substrate 10. A discharge opening is formed.

In this case, the shape of the light emitting opening is very important because it greatly affects the luminance characteristics and power consumption characteristics.

The shape of the light emitting opening is described in more detail with reference to FIGS. 1D and 1E as follows.

The light emission opening 25 shown in FIG. 1E is formed by an exposure, development, and etching process using a pattern mask after forming a photoresist thin film on the upper surface of the light absorption layer 20. The shape of the opening 25 depends on the pattern shape formed in the pattern mask 30 shown in FIG.

More specifically, the pattern mask 30 is a chromium thin film layer 32 that is thin so as not to transmit light to the entire surface of the transparent substrate, in one embodiment, the glass substrate having the same area as the transparent substrate 10 on which the organic electroluminescent device is to be formed. ), And then, an opening having a predetermined shape is formed in the chromium thin film region corresponding to the area of each unit organic electroluminescent element in the chromium thin film layer 32.

At this time, the shape of the opening is a rectangle having a size smaller than the size of the strip region 33 at least one inside the strip region 33 in which the chromium thin film layer 32 is stripped in a rectangular shape so as to have a predetermined area. It has a shape in which the chrome thin film pattern 34 is located.

At this time, when at least one rectangular chrome thin film pattern 34 has a shape as shown in FIGS. 1D and 1E, the light emission opening 25 may have a rectangular band shape or a light emission opening 27. Will have a lattice shape.

The shape of the light emission openings 25 and 27 serves to cause an optical illusion of the user's eyes so that the chrome thin film pattern 34 feels as if it does not exist. This does not occur, thereby reducing the power consumption by the area of the chrome thin film pattern 34.

Indium tin oxide thin film having high transparency and low electrical resistance over the entire area as shown in FIG. 1F or 1G is formed on the upper surface of the light emitting openings 25 and 27 formed in the upper portion of the light absorbing layer 20 in this manner. (Indum Tin Oxide film, hereinafter referred to as ITO thin film) 50 is formed.

Thereafter, the ITO thin film 50 corresponding to a row between the rows of the light emitting openings 25 and 27 arranged in a matrix form in the ITO thin film 50 formed over the entire area of the light absorption layer 20. Is etched, that is, the ITO thin film 50 is etched in a stripe shape so that the light emitting openings 25 and 27 are separated in units of columns.

Hereinafter, as shown in FIG. 1G, each ITO thin film 50 separated in a stripe form will be referred to as an anode electrode, and reference numeral 52 will be given.

Thereafter, as illustrated in FIG. 1H, a pad metal 60 is coated to a predetermined thickness over the entire surface of the anode electrode 52, and the pad metal 60 is anode electrode 52 as shown in FIG. 1I. It is patterned to have a rod shape that wraps along one edge of it.

The pad metal 60 supports the role of the anode electrode 52, which is much lower than the electrical resistance of the anode electrode 52, and has poor electrical characteristics. The pad metal 60 will be defined as an auxiliary electrode, hereinafter referred to as pad electrode. 62 is given.

Thereafter, as shown in FIG. 1J, an organic electroluminescent layer 80 to be described later is formed on the upper surfaces of the pad metal 62 and the light absorbing layer 20, and a cathode electrode (described later) is described in detail on the upper surface of the organic electroluminescent layer 80. 90 is formed. If the organic electroluminescent layer 80 is in contact with the pad metal 62, the result is that the pad metal 62-the organic electroluminescent layer 80-the cathode electrode 90 is short-circuited. As illustrated in FIG. 1J, the inter-insulator thin film layer 70 is formed on the upper surface of the pad metal 62 to have a predetermined thickness in order to prevent the current amount applied to the electrode 52 from rapidly decreasing.

Subsequently, the opening 72 is formed on the upper surface of the inter-insulator thin film layer 70 in the same form as the light absorbing layer 20 as shown in FIG. 1K.

Thereafter, as shown in FIG. 1L, the organic electroluminescent layer 80 is formed to have a predetermined thickness inside the opening 72 and around the opening 72 formed on the upper surface of the inter-insulator thin film layer 70.

Subsequently, a cathode electrode 90 having a direction perpendicular to the anode electrode 52, that is, a row direction, covering all organic electroluminescent layers 70 belonging to one row on a top surface of each organic electroluminescent layer 70 is provided in units of rows. Is formed.

In the case of <Example 1> described in detail above, in order to prevent the pad metal 62 and the organic electroluminescent layer 80 from being shorted to each other, the inter-insulator thin film layer 70 must be formed. In the present invention, an embodiment in which the inter-insulator thin film layer 70 is performed by a part of the light absorbing layer 20 in place to simplify the process and increase the mass productivity of the product is described.

<Example 2>

As shown in FIG. 2B, an ITO electrode 120 having a high transparency to a predetermined thickness is coated on the upper surface of the transparent substrate 110 illustrated in FIG. 2A.

Thereafter, as illustrated in FIG. 2C, the ITO electrode 120 coated on the upper surface of the transparent substrate 110 is patterned in a stripe form extending in one direction while being parallel to each other.

Hereinafter, the ITO electrode 120 subjected to the patterning as described above will be defined as an anode electrode, and reference numeral 122 will be given.

Thereafter, as illustrated in FIG. 2D, the pad metal 130 is coated to a predetermined thickness on the entire surface of one side of the transparent substrate 110 on which the anode electrode 112 is formed, and then, as illustrated in FIG. 2E, the pad metal ( The remaining portion except for the portion in contact with the long side edge of the anode electrode 122 is selectively removed by a method such as etching. Hereinafter, reference numeral 132 will be given to the pad metal.

Thereafter, as illustrated in FIG. 2F, the light absorption layer 140 is formed on the upper surface of the transparent substrate 110 on which the pad metal 132 and the anode electrode 122 are formed.

The light absorption layer 140 is composed of a non-conductive chromium oxide layer 142, a conductive chromium oxide layer 145, and a non-conductive chromium oxide layer 146.

In this case, the non-conductive chromium oxide layer 142 of the light absorbing layer 140 is directly formed on the pad metal 132, so that a separate inter-insulator thin film layer is not required as shown in <Example 1>.

Subsequently, the light emitting openings 147 and 148 having the same shape as the light emitting openings 25 and 27 of FIGS. 1D and 1E of the first embodiment are shown on the upper surface of the light absorbing layer 140. 2H, 2I, and 2J, and the like, and by a method such as plasma etching.

Thereafter, as shown in FIG. 2K, an organic electroluminescent layer 150 is formed inside the light emitting openings 147 and 148 and around the light emitting openings 147 and 148, and then, on the upper surface of the organic electroluminescent layer 150. As shown in FIG. 2L, the cathode electrode 140 is formed to complete the fabrication of the unit organic electroluminescent device.

In the case of the organic electroluminescent device manufactured by the manufacturing method as described above, high brightness characteristics, brightness characteristics and mass productivity without the use of circularly polarizing plates or the like acting as a cause of increasing power consumption by the light absorption layer as in <Example 1> Characteristics can be satisfied. This will be described with reference to <Table 1> and <Table 2>, which are the results of experiments by various controls.

rescue reflectivity reflectivity General Indoor (165lux) Office (325lux) Standard (500 lux) Shade (1200lux) Experimental Example 1 20.7% 38.8 20.6 14.2 7.0 Experimental Example 2 16.7% 56.6 25.2 17.0 8.1 Comparative Example 1 60% 14.6 8.4 6.2 3.8 Comparative Example 2 4% 192.4 98.6 64.8 28.2

rescue Power Consumption Experimental Example 1 100% Experimental Example 2 100% Comparative Example 1 100% Comparative Example 2 233%

The structure of the organic electroluminescent device of <Experimental Example 1> in <Table 1> and <Table 2> has a predetermined aperture ratio in the light absorption layer 140 formed between the anode electrode 122 and the cathode electrode 160 as described above. The light emitting openings 147 and 148 are formed to have a structure.

The structure of the organic electroluminescent device of <Experimental Example 2> is a transparent substrate for further improving the light emission openings 147 and 148 and optionally the luminance ratio to have a predetermined aperture ratio between the anode electrode 122 and the cathode electrode 160. An additional anti-reflection coating layer (AR coating) (not shown), which serves to increase the brightness by a method of scattering incident light in relation to the outer side of the 110 or the anode electrode 122, is further formed. Has a structure.

On the other hand, <Comparative Example 1> is an organic electroluminescent device which is a control contrasted with <Experimental Example 1> and <Experimental Example 2, since no light absorbing layer and scattering coating layer are formed, and <Comparative Example 2> obtains high brightness. For the purpose, the organic electroluminescent device is provided with a circular polarizing plate, which is another control, which is contrasted with <Experimental Example 1> and <Experimental Example 2>.

At this time, the luminance ratio is obtained by <Equation 1>.

In this case, the reflectance of <Equation 1> is a spectrophotometer at a rate at which external light is reflected from the organic electroluminescent devices of <Experimental Example 1>, <Experimental Example 2>, <Comparative Example 1>, and <Comparative Example 2> It is measured using a spectrophtometer.

In the meantime, the luminance to be substituted in Equation 1 is the luminance under the environment in which the experiment is performed, that is, the luminance in the general indoor (165 lux), the office (325 lux), the standard (500 lux), and the shade (1200 lux).

Referring to the results of <Table 1>, the reflectance of <Experimental Example 1> was 20.7%, the reflectance of <Experimental Example 2> was 16.7%, the reflectance of <Comparative Example 1> was 60%, and the reflectance of <Comparative Example 2> was Experiment was 4%. In this case, the reflectance is reflectance according to light of 550 nm.

At this time, according to the experimental results, the greater the reflectance has a result of lowering the luminance ratio.

More specifically, the organic electroluminescent device having the luminance corresponding to Experimental Example 1 under the condition of standard (500 lux), that is, the light absorbing layer 140 and the light emitting openings 147 and 148 has a luminance ratio of about 14.2: 1. That is, the organic electroluminescent device corresponding to Experimental Example 2, that is, the scattering coating layer formed together with the light absorption layer has a luminance ratio of about 17.0: 1, and the luminance ratio was 6.2 in the Comparative Example 1, in which the light absorption layer and the scattering coating layer were not formed. It appeared as: 1, and in Comparative Example 2 the luminance ratio was 64.8: 1.

That is, when the standard condition, that is, the illuminance is 500 lux, <Comparative Example 1> shows that the display performance is remarkably degraded because the high reflectance of about 60% does not satisfy the 8: 1 condition which is the minimum luminance ratio suitable for the display. On the contrary, it can be seen that <Experimental Example 1>, <Experimental Example 2> and <Comparative Example 2> satisfactorily satisfy at least the 8: 1 condition which is the minimum luminance ratio.

However, when looking at the power consumption side with reference to <Table 2>, the power consumption of <Experimental Example 1>, <Experimental Example 2>, <Comparative Example 1> are all similar, when their power consumption is 100%, It can be seen that <Comparative Example 2> requires about 233% power consumption as compared to <Experimental Example 1>, <Experimental Example 2>, and <Comparative Example 1>.

The reason for the high power consumption in <Comparative Example 2> in which the circularly polarizing plate is used as described above is that the circularly polarizing plate is a means of obtaining high brightness as shown in <Table 1>, but is blocked by the circularly polarizing plate instead of implementing the high brightness. This is because the power consumption is greatly increased because the intensity of the current applied to the organic electroluminescent device is applied much more than the <Experimental Example 1>, <Experimental Example 2>, and <Comparative Example 1> to compensate for the insufficient amount of light. .

That is, when the organic electroluminescent device using the circular polarizing plate is used as a portable display device, for example, the charging time is very short due to the high power consumption, but at the same time satisfies the minimum luminance ratio sufficiently. It can be sufficiently overcome by <Example 1> and <Example 2> power consumption is very low, and has a very advantageous aspect in terms of mass productivity.

<Example 3>

In FIG. 3, another embodiment according to the present invention is illustrated, in which the anode electrode 220 is formed on the upper surface of the transparent substrate 210 as in Comparative Example 1, and the anode electrode. After the pad metal 240 and the organic electroluminescent layer 250 are formed on the upper surface of the 220, the light absorbing member 270 is formed on the organic electroluminescent device in which the cathode electrode 260 is formed on the upper surface of the organic electroluminescent layer 250. <Example 3> can achieve the same performance as <Example 1> and <Example 2>, without changing the structure of the conventional organic electroluminescent device.

In order to implement this, at least two or more layers of the chromium oxide thin film layer 273, the chromium oxide thin film layer 274, and the chromium oxide thin film layer 275 are alternately formed on the thin transparent substrate 272 to form a light absorbing layer 276. 276 is provided with light emitting openings 147a and 148a as described in detail in <Example 1> and <Example 2>.

A transparent adhesive 277 is applied to the opposite side of the light absorbing layer 276 of the transparent substrate 272, and the transparent substrate 272 and the organic electroluminescent device are bonded to each other in an aligned state, whereby the organic electroluminescent device has high brightness characteristics. It may have both low power consumption characteristics and mass productivity characteristics.

As described above in detail, it is effective to greatly improve the mass productivity of the light absorbing layer which induces low power consumption of the organic electroluminescent device by using high brightness characteristics and optical illusion characteristics.

Claims (4)

A substrate through which light is transmitted; An anode electrode plate formed of at least one piece so as not to be mutually shorted on one surface of the substrate; A light absorption thin film layer composed of at least one layer to be insulated from one surface of the anode electrode plate, and a light emission opening formed by opening a portion corresponding to an upper surface of the anode electrode plate in the light absorption thin film layer in a predetermined shape; External light absorbing means; An organic electroluminescent layer formed in the light emitting opening and in contact with the anode electrode; An organic electroluminescent device formed on top of said organic electroluminescent layer, said cathode electrode intersecting with said anode electrode. The method of claim 1, wherein the light absorption thin film layer An organic electroluminescent device comprising a non-conductive chromium oxide thin film layer in contact with the anode electrode, a conductive chromium thin film layer formed on an upper surface of the chromium oxide thin film layer, and a chromium oxide thin film layer formed on the chromium thin film layer. The organic electroluminescent device according to claim 1, wherein at least one light absorbing piece is arranged in a matrix form inside the light emitting opening. The organic electroluminescent device according to claim 3, wherein one light absorption piece is formed at a central portion of the opening.