KR100899424B1 - Organic light emitting diode display - Google Patents

Abstract

The present invention relates to an organic light emitting display device, comprising: a device substrate, a first electrode formed on the device substrate and including a reflective film thereunder, an organic light emitting layer formed on the first electrode, and formed on the organic light emitting layer An organic electroluminescent device comprising a second electrode; And a light emitting protective layer formed on a front surface of the device substrate on which the organic light emitting diode is formed and including a tapered pattern at a position corresponding to the organic light emitting layer.

The light emitting protection layer may implement an organic light emitting display device having better light efficiency by protecting the organic light emitting diode including the organic light emitting layer from outside air and condensing light to the outside.

Luminous protective film, light efficiency

Description

Organic light emitting diode display

The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device having a light emitting protective film including a tapered pattern.

In general, a flat panel display (FPD) is a liquid crystal display (LCD), a field emission display (FED), an organic light emitting diode display (OLED) ) And the like.

Among the flat panel display devices, the organic light emitting display device includes an organic light emitting layer made of organic material, and thus is vulnerable to external moisture.

Accordingly, in order to protect the organic device from external moisture and the like, a sealant is applied to the edge of the device substrate on which the organic light emitting device is formed, and a sealing substrate is bonded to the upper portion via the sealant.

As a result, the device substrate and the encapsulation substrate bonded through the sealant separate the organic electroluminescent device from the outside, thereby protecting the organic light emitting layer of the organic electroluminescent device.

In this case, in order to further protect the organic light emitting layer, a separate light emitting protective film may be formed on the entire surface of the device substrate including the organic light emitting device.

However, the light emitting protective layer may not only serve to protect the organic light emitting layer, but may also affect light efficiency during light emission.

In more detail, the light efficiency is largely divided into an internal light efficiency and an external light efficiency, and the internal light efficiency can obtain an efficiency close to 100% by using a phosphorescent material.

On the other hand, the external light efficiency is only about 20% of the light emitted to the outside due to diffuse reflection due to refraction and diffraction due to the internal laminated structure during the light emission of the organic light emitting layer.

Therefore, if only a part of the light that is extinguished in the organic light emitting display can be emitted to the outside, a very large light efficiency improvement effect can be obtained.

However, since the conventional light emitting protective film is uniformly formed on the organic EL device, there is a limit in terms of improving the light efficiency.

Accordingly, an object of the present invention is to provide an organic electroluminescent display device having improved light efficiency by forming a light emitting protective film including a tapered pattern on an entire surface of an organic electroluminescent device. have.

The object of the present invention includes a device substrate, a first electrode formed on the device substrate and including a reflective film at the bottom, an organic light emitting layer formed on the first electrode, a second electrode formed on the organic light emitting layer Organic electroluminescent device; And

And a light emitting protective film formed on an entire surface of the device substrate on which the organic electroluminescent device is formed and including a tapered pattern at a position corresponding to the organic light emitting layer.

It is achieved by an electroluminescent display device.

Therefore, the organic electroluminescent display device of the present invention may be provided with a light emitting protective film including a tapered pattern to protect the organic electroluminescent device including the organic light emitting layer, and at the same time, better light efficiency may be expected.

Details of the above objects and technical configurations and the effects thereof according to the present invention will be more clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

In the drawings, the lengths, thicknesses, etc. of layers and regions may be exaggerated for convenience. Also, like reference numerals denote like elements throughout the specification.

<Example 1>

1A to 1D are cross-sectional views illustrating a manufacturing process of an organic light emitting display device according to a first embodiment of the present invention.

First, referring to FIG. 1A, a plurality of organic EL devices are formed on the device substrate 10.

In this case, the device substrate 10 may be formed of an insulator such as a glass substrate or a plastic substrate.

The organic electroluminescent device formed on the device substrate 10 has a first electrode 20 including a reflective film (not shown) and an organic light emitting layer 21 formed on the first electrode 20. And a second electrode 22 formed on the organic light emitting layer 21. In this case, a hole injection layer and a hole transport layer may be formed between the organic light emitting layer 21 and the first electrode 20, and an electron transport layer and an electron injection layer between the organic light emitting layer 21 and the second electrode 22. This may be formed.

In addition, the organic electroluminescent device may be an active organic electroluminescent device including a thin film transistor, and a general active organic electroluminescent device may be understood by the following detailed description with reference to FIG. 4.

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4 is a partial cross-sectional view of an organic EL device.

First, referring to FIG. 4, a buffer layer (not shown) may be formed on the substrate 10. The buffer layer (not shown) serves to prevent diffusion of moisture or impurities generated in the substrate 10.

Subsequently, amorphous silicon is formed on the buffer layer (not shown), wherein the amorphous silicon layer is formed by physical vapor deposition (Pspma) or plasma enhanced chemical vapor deposition (PECVD) or low pressure chemical vapor deposition (LPCVD), such as a sputtering apparatus. It can be formed using a chemical vapor deposition (Chemical Vapor Deposition) device.

In addition, when the amorphous silicon layer is formed, or after the formation of the dehydrogenation process may be carried out to lower the concentration of hydrogen.

Subsequently, the amorphous silicon layer is crystallized to form a polycrystalline silicon layer. The method of crystallizing the amorphous silicon layer may include Excimer Laser Annealing (ELA), Sequential Lateral Solidification (SLS), Metal Induced Crystallization (MIC), Metal Induced Later Crystallization (MILC), or Super Grained Silicon (SGS).

Subsequently, the polycrystalline silicon layer is patterned to form a semiconductor layer 110 having a predetermined pattern.

Subsequently, the gate insulating layer 120 is formed on the entire surface of the substrate on which the semiconductor layer 110 is formed to protect the devices formed under the gate insulating layer 120 and electrically insulate the devices to be formed on the gate insulating layer 120.

Subsequently, a gate metal layer is deposited on the gate insulating layer 120 using any one of aluminum (Al), aluminum alloy (Al alloy), molybdenum (Mo), and molybdenum alloy (Mo alloy).

Subsequently, the gate metal layer is patterned to form a gate electrode 130 corresponding to a predetermined region of the semiconductor layer 110.

Subsequently, using the gate electrode 130 as a mask, a process of implanting any one of N-type and P-type impurities is performed to inject the source / drain regions 110a and 110b and the channel region 110c into the semiconductor layer 110. ). In this case, the semiconductor layer 110 is divided into the source / drain regions 110a and 110b and the channel region 110c. The region into which the impurities are injected by the impurity implantation process is the source / drain regions 110a and 110b. This is because a region in which impurities are not injected by the gate electrode 130 is defined as a channel region 110c in which a channel is formed during thin film transistor driving.

Subsequently, an interlayer insulating layer 140 is formed on the entire surface of the substrate, and the interlayer insulating layer 140 protects devices formed at the bottom and electrically insulates the devices to be formed on the interlayer insulating layer 140.

In this case, the buffer layer (not shown), the gate insulating layer 120 and the interlayer insulating layer 140 may be formed of SiO 2 or SiN x, and may be formed of a plurality of layers formed therefrom.

Subsequently, contact holes are formed to penetrate the interlayer insulating layer 140 and the gate insulating layer 120 to expose portions of the source / drain regions 110a and 110b of the semiconductor layer 110.

Subsequently, a thin film transistor is formed on the interlayer insulating layer 140 by forming source / drain electrodes 150a and 150b having a predetermined pattern connected to the source / drain regions 110a and 110b of the semiconductor layer 110 through the contact hole. To form.

The source / drain electrodes 150a and 150b may be formed of any one of aluminum (Al), aluminum alloy (Al alloy), molybdenum (Mo), and molybdenum alloy (Mo alloy).

Next, the thin film transistor passivation layer 160 is formed on the entire surface of the substrate, and the thin film transistor passivation layer 160 may be formed of SiO 2 or SiN x and a plurality of layers thereof.

Subsequently, a planarization layer 170 is formed on the thin film transistor passivation layer 160. The planarization layer 170 may be formed of an organic layer, and acrylic, BCB (benzocyclobutene), and poly (II) may be used to alleviate the step on the substrate. Any one selected from the group consisting of meads can be used.

Subsequently, a region of the thin film transistor passivation layer 160 and the planarization layer 170 is etched to form a via hole exposing any one of the source / drain electrodes 150a and 150b.

Subsequently, a first electrode 20 is formed on the planarization film 170. The first electrode 20 is connected to any one of the source / drain electrodes 150a and 150b exposed through the via hole. The first electrode 20 is formed of a transparent electrode such as indium tin oxide (ITO) or indium zinc oxide (IZO).

In this case, the bottom of the first electrode 20 may include a reflective film (not shown) for reflecting light to provide a top emission organic light emitting device. The reflective film is made of any one group consisting of Pt, Au, Ir, Cr, Mg, Ag, Al, and alloys thereof, and has a structure laminated with the first electrode 20.

Subsequently, a pixel defining layer 25 having an opening exposing a predetermined region of the first electrode 20 is formed on the entire surface of the substrate. The pixel defining layer 25 may be one material selected from the group consisting of benzocyclobutene (BCB), an acrylic polymer, and polyimide.

Subsequently, the organic light emitting layer 21 is formed on the first electrode 20 exposed through the opening, and the second electrode 22 is formed on the entire upper surface of the substrate to implement the organic light emitting device. In this case, a hole injection layer and a hole transport layer may be formed between the organic light emitting layer 21 and the first electrode 20, and an electron transport layer and an electron injection layer between the organic light emitting layer 21 and the second electrode 22. This may be formed.

Although the thin film transistor has only a top gate electrode structure described above, a thin film transistor having a bottom gate electrode structure, which is a well-known technology, may be applied.

Next, referring to FIG. 1B, a light emitting protective film 23 is formed on the entire surface of the elementary plate 10 on which the organic light emitting diodes are formed. The emission protective film 23 is for protecting the organic electroluminescent device including the organic light emitting layer 21 from external air.

The light emitting protective layer 23 may be formed of a transparent material among organic materials and water, but may be generally formed of any one of SiNx, SiO 2, and Al203, and may have a thickness of about 10 μs to about 5000 μs.

In this case, the protective film effect to protect the organic electroluminescent device from the outside air is lowered when formed below 10 kW, and the light efficiency and the thin film formation process time may be lowered when formed above 5000 kW.

Next, referring to FIG. 1C, a wet or dry etching process may be performed on the light emitting protective layer 23 to form a tapered pattern 23a having a trapezoidal shape at a position corresponding to the organic light emitting layer 21.

In the wet etching method, a photosensitive film (not shown) having a predetermined pattern is formed on the light emitting protective film 23 through an exposure and development process, and then the light emitting protective film 23 is sprayed using a spray method in which an etchant is sprayed by a nozzle. Etch it. At this time, the injection pressure may be adjusted to form a tapered pattern 23a having a reverse taper shape.

Such a detailed description of the light emitting protective film 23 will be understood by the following detailed description with reference to FIG. 2.

Next, referring to FIG. 1D, the sealant 24 is applied to the edge portion of the device substrate 10, the sealing substrate 30 is aligned, and then the bonding process of pressing the seal substrate 30 is performed. And the sealing substrate 30 are bonded.

Therefore, the encapsulation substrate 30 and the device substrate 20 are sealed and the organic electroluminescent element accommodated in the internal space can be protected from the outside air. The encapsulation substrate 30 may be formed of glass, plastic, or the like.

In this case, the sealant 24 may be a UV curing agent or thermosetting agent such as epoxy, and may contain a spacer such as polymer beads or silica particles.

The encapsulating substrate 30 may include a moisture absorbent (not shown), and the moisture absorbent includes one material selected from the group consisting of BaO, GaO, zeolite, CaO, and metal oxide. It may be used to form, it is also possible to use a transparent absorbent PNPL.

2 is a cross-sectional view illustrating light emission of an organic light emitting display device according to a first exemplary embodiment of the present invention.

Referring to FIG. 2, the light emitting protective layer 23 is formed of a tapered pattern 23a having a trapezoidal shape, and the taper a may be formed according to the thickness of the light emitting protective layer 23 or the characteristics of the organic light emitting layer 21. It can be adjusted between 90 ° and 180 °.

Therefore, even if the light emitted from the organic light emitting layer 21 spreads in all directions due to diffraction and refraction, the light emitted irregularly by the tapered pattern 23a of the light emitting protective film 23 is collected as shown in the drawing. The light efficiency can be improved.

As a result, the light emitting protective film 23 including the tapered pattern 23a having the trapezoidal shape protects the organic EL device including the organic light emitting layer 21 and is better than the light emitting protective film having a uniform shape according to the prior art. Light efficiency can be obtained.

<Example 2>

3 is a cross-sectional view illustrating light emission of an organic light emitting display device according to a second exemplary embodiment of the present invention.

According to the second embodiment of the present invention, since the configuration except for the light emitting protective film 23 including the tapered pattern 23a overlaps with the first embodiment, the detailed description other than the light emitting protective film 23 including the tapered pattern 23a is provided. The description is omitted to avoid duplication.

Referring to FIG. 3, a plurality of organic electroluminescent devices are formed on the device substrate 10.

A light emitting protective film 23 is formed on the entire surface of the device substrate 10 on which the organic EL device is formed. The light emitting protective film 23 is to protect the organic electroluminescent device including the organic light emitting layer 21 from the outside air.

The light emitting protective layer 23 may be formed of a transparent material among organic materials and water, but may be generally formed of any one of SiNx, SiO 2, and Al203, and may be formed to have a thickness of 10 μs to 5000 μs.

In this case, when the protective film is formed at 10 kW or less, the protective film effect of protecting the organic EL device from external air is reduced.

Next, a wet or dry etching process is performed on the light emitting protective layer 23 to form a tapered pattern 23a having a triangular shape at a position corresponding to the organic light emitting layer 21.

In the dry etching method, a photoresist (not shown) is coated on the light-emitting protective layer 23, and then exposed and developed in a predetermined pattern using a half-tone mask, followed by dry etching. The triangular pattern may be transferred to the light emitting protective layer 23.

In this case, one or more of the triangular tapered patterns 23a may be formed. The taper a may be formed between 90 ° and 180 ° depending on the thickness of the light emitting protective layer 23 or the characteristics of the organic light emitting layer 21. I can regulate it.

More specifically, the light emitted from the organic light emitting layer 21 is spread in all directions due to the diffraction and refraction of the light.

In this case, since the light emitting protective layer 23 is formed as a tapered pattern 23a having a triangular shape, light efficiency may be improved by condensing light that emits irregularly as shown in the drawing.

Accordingly, the light emitting protective film 23 including the tapered pattern 23a having one or more triangular shapes protects the organic electroluminescent device including the organic light emitting layer 21 and has a uniform shape according to the prior art. Better light efficiency than the light emitting protective film can be obtained.

In Example 1 and Example 2 according to the present invention described above, the pattern of the light emitting protective film has been described centering on the trapezoidal and triangular patterns, but the present invention is not limited thereto, and the overall light emitting protective film having a pattern capable of improving light efficiency may be used. Can be applied across.

Therefore, it will be understood by those skilled in the art that the present invention may be variously modified and changed without departing from the spirit and scope of the present invention as set forth in the claims below.

1A to 1D are cross-sectional views illustrating a manufacturing process of an organic light emitting display device according to a first embodiment of the present invention.

2 is a cross-sectional view illustrating light emission of an organic light emitting display device according to a first exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating light emission of an organic light emitting display device according to a second exemplary embodiment of the present invention.

4 is a partial cross-sectional view of an organic EL device.

<Explanation of symbols for the main parts of the drawings>

10: device substrate 20: first electrode

21: organic light emitting layer 22: second electrode

23: light emitting protective film 23a: tapered pattern

30: sealing substrate 110: semiconductor layer

110a, 110b: source / drain area 110c: channel area

120: gate insulating film 130: gate electrode

140: interlayer insulating film 150a, 150b: source / drain electrodes

160: thin film transistor protective film 170: planarization film

Claims (6)

An organic electroluminescent device comprising a device substrate, a first electrode formed on the device substrate, the first electrode including a reflective film below, an organic light emitting layer formed on the first electrode, and a second electrode formed on the organic light emitting layer; And And a light emitting protective layer formed on a front surface of the device substrate on which the organic light emitting diodes are formed and including a tapered pattern at a position corresponding to the organic light emitting layer.  The method of claim 1, And the light emitting protective layer is formed of a transparent material.  The method of claim 1, And the light emitting protective layer is formed of any one of SiNx, SiO 2 and Al203. The method of claim 1, And the tapered pattern is a trapezoid and one or a plurality of triangular patterns. The method of claim 1, And the taper is between 90 ° and 180 °. The method of claim 1, And a thin film transistor connected to the first electrode and including a semiconductor layer under the first electrode.

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