KR100617193B1 - Dual Organic Electroluminescence display device and Fabrication Method for the same - Google Patents

Abstract

The present invention relates to an organic EL, and more particularly to a bidirectional organic EL display element. As described above, the bidirectional organic EL display device according to the present invention includes a back light emitting pixel electrode and a common electrode in the organic EL having a pixel driver formed on the substrate and emitting the front light. It is configured by.

Anode electrode, cathode electrode, hole injection layer, organic light emitting layer, electron transport layer

Description

Bidirectional organic EL display device and method of manufacturing the same {Dual Organic Electroluminescence display device and Fabrication Method for the same}

1 is a cross-sectional view of a conventional organic EL

2A to 2D are cross-sectional views of a conventional organic EL manufacturing process

3 is a pixel circuit diagram of a conventional active drive organic EL display.

4 is a plan view of a pixel structure of an active driving organic EL display

5A to 5J are cross-sectional views of a bidirectional organic EL display panel manufacturing process according to the present invention.

Fig. 6 is a circuit diagram of a bidirectional organic EL display panel according to the present invention.

7 is a plan view of a pixel structure of a bidirectional organic EL display panel according to the present invention.

* Description of symbols on the main parts of the drawings *

21 substrate 22 semiconductor layer

22a, 22c: source / drain region 22b: channel region

23 gate insulating film 24 gate electrode

25 interlayer insulating film 26 electrode line

27: first anode electrode 28: planarization film

29 contact hole 30 second anode electrode

31 insulating film 32 hole injection layer

33: hole transport layer 34: organic light emitting layer

35 electron transfer layer 36 electron injection layer

37: first cathode electrode 38: shadow mask

39: second cathode electrode 40: protective film

The present invention relates to an organic EL, and more particularly to a bidirectional organic EL device and a method of manufacturing the same.

In general, the pixel portion of an active matrix organic electroluminescence device (AMOELD) is a switching thin film transistor, a driving thin film transistor, a driving capacitor, a storage capacitor, an anode, It is composed of an organic material layer and a common electrode (cathod).

FIG. 1 is a cross-sectional view of a pixel different from the related art based on a dual driving thin film transistor.

As shown in FIG. 1, a conventional organic EL device includes a plurality of pixels defined by regions intersecting a plurality of pixel electrodes 8 and a common electrode (metal common electrode) 15 each formed on a plurality of organic substrates 1. An organic light emitting layer 12 formed on the thin film transistor A, a thin film transistor A formed on the glass substrate 1, and having a drain electrode electrically connected to the pixel electrode 8, and the pixel electrode 8 and the organic light emitting layer 12. The hole injection layer 10 and the hole transport layer 11 formed between the light emitting layer 12 and the electron transport layer 13 and the electron injection layer stacked between the organic light emitting layer 12 and the metal common electrode 15 are formed. It consists of 14.

The thin film transistor A is formed on one region of the glass substrate 1 and includes a semiconductor layer 2 composed of source / drain regions 2a and 2c and a channel region 2b, and the semiconductor layer 2 The gate insulating film 3 is formed on the entire surface of the glass substrate 1 including the gate electrode 3 and the gate electrode 4 formed on the gate insulating film 3 above the channel region 2c.

 In this case, the boundary between the source / drain regions 2a and 2c and the channel region 2b is aligned with both edges of the gate electrode 4.

An interlayer insulating film 5 is formed on the thin film transistor A to open the source region 2a and the drain region 2c. The source / drain region is formed through an open portion of the interlayer insulating layer 5. Electrode lines 6 electrically connected to 2a) and 2c are formed.

A planarization insulating film 7 for opening the electrode line 6 electrically connected to the drain region 2c is formed on the front surface including the interlayer insulating film 5 and the electrode line 6.

The pixel electrode 8 is formed on the planarization insulating layer 7, and the pixel electrode 8 is electrically connected to the drain region 2b of the thin film transistor A through an open portion of the planarization insulating layer 7. Will be.

The insulating film 9 is formed so that a part of the pixel electrode 8 is covered between the neighboring pixel electrodes 8.

The common electrode includes a metal common electrode 15 stacked on the electron injection layer 14, and a passivation layer 16 is formed on the common electrode.

Next, the manufacturing method of the organic electroluminescent element which concerns on the prior art of the said structure is demonstrated.

2A to 2D are sectional views of the manufacturing process of the organic EL device according to the prior art.

First, as shown in FIG. 2A, the semiconductor layer 2 is formed on the glass substrate 1 using, for example, polycrystalline silicon, for use as an active layer of the thin film transistor, and thereafter, the region where the thin film transistor is to be formed. That is, the semiconductor layer 2 is patterned so as to remain only in the thin film transistor predetermined region.

Subsequently, the gate insulating film 3 and the conductive film for the gate electrode are sequentially stacked on the entire surface, and then the gate electrode 4 is formed by patterning the conductive film for the gate electrode so as to remain on one region of the patterned semiconductor layer 2. .

The source / drain regions 2a and 2c of the thin film transistor are then thermally treated by implanting impurities such as boron (B) or phosphorus (P) into the semiconductor layer 2 using the gate electrode 4 as a mask. Form.

At this time, the semiconductor layer 2 into which the impurity ions are not implanted is the channel region 2b.

Next, an interlayer insulating film 5 is formed on the entire surface, and the interlayer insulating film 5 and the gate insulating film 3 are selectively removed so that the source / drain regions 2a and 2c of the thin film transistor are exposed. To form.

In addition, the first metal layer may be formed to a thickness sufficient to fill the contact hole, and the first metal layer may be selectively removed to remain only in the contact hole and the region adjacent to the contact hole, thereby forming a source metal layer 2a (2b). Each of the electrode lines 6 is electrically connected.

Next, the planarization insulating layer 7 is formed on the entire surface to planarize the entire surface, and the planarization insulating layer 7 is selectively removed so that the electrode line 6 connected to the drain region 2c is exposed to form a contact hole. A second metal film having high reflectance and work function (reworking function) values such as Al, Mo, Ag, and Au are deposited on the entire surface.

In this case, a second metal film is formed in the contact hole so that the second metal film is connected to the electrode line 6 under the contact hole.

Subsequently, the second metal film is selectively removed to remain only in the pixel portion to form a transparent pixel electrode 8 such as ITO electrically connected to the drain region 2c at the lower portion through the electrode line 6. .

Subsequently, as shown in FIG. 2B, the insulating film 9 is formed so that a portion of the pixel electrode 8 is covered between the neighboring pixel electrodes 8.

As illustrated in FIG. 2C, the hole injection layer 10 and the hole transport layer 11 are deposited as a common organic layer, and the R, G, and B organic light emitting layers 12 are formed using a shadow mask. Are deposited respectively.

Subsequently, organic material layers such as the electron transport layer 13 and the electron injection layer 14 are sequentially formed on the entire surface.

Next, as shown in FIG. 2D, a metal common electrode 15 is formed.

In this case, the metal common electrode 15 deposits a metal material having a low work function such as aluminum (Al).

After the protective film 16 is formed on the metal common electrode 15 to protect the organic material layer from oxygen or moisture, the sealing cap is attached using a sealant, a transparent substrate, or a metal cap. The organic EL device fabrication is completed.

In this case, in the bottom emission type, a driving type organic EL may be manufactured using a getter and a sealing cap without forming the protective layer 16.

3 is a pixel circuit diagram of a conventional active drive organic EL display, and FIG. 4 is a plan view of a pixel structure of an active drive organic EL display, wherein a data signal is stored in a capacitor while a switching transistor is turned on by a scan signal. The driving transistor then supplies a current proportional to the data voltage to the organic EL.

In the case of fabricating an active driving type organic EL device in this manner, the driving circuit occupies most of one pixel, and the opening ratio is low due to the small portion of light output. If the compensation circuit is applied, the area occupied by the pixel driving circuit is even larger. You lose.

That is, when the compensation circuit is applied to the same pixel size, the aperture ratio is significantly lowered.

Accordingly, an object of the present invention has been made in view of the above-mentioned problems of the prior art, and uses a region occupied by a pixel driving circuit to simultaneously implement a back emission organic EL device and a top emission organic EL device. It is to provide.

       According to a feature of the present invention for achieving the above object, in an organic EL having a pixel driver is formed on the substrate and the front light emitting, the organic EL is common to the back light emitting pixel electrode so that the rear light emitting on the pixel driving region It is configured to include an electrode.

        Preferably, the bottom emission pixel electrode and the common electrode are formed simultaneously with the top emission pixel electrode and the common electrode formed on the substrate.

        According to another aspect of the present invention for achieving the above object, forming a pixel driver on a substrate, forming a first anode electrode on the pixel driver, a first on the pixel driver and the first anode electrode Forming a second anode electrode, forming an insulating film to expose a portion of the first anode electrode and to cover the second anode electrode, and sequentially forming a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer; And forming a first cathode electrode over the entire area of the light emitting layer, and covering the first cathode electrode area with a shadow mask to form a second cathode electrode.

       Preferably, the first anode electrode is for back emission and the second anode electrode is for top emission.

       The first anode electrode for bottom emission is a transparent conductive film having a high work function value, and the second anode electrode for top emission is a conductive film having a high reflectance and a work function.

       In addition, the second anode electrode uses one of Cr, Al, Mo, Ag and Au, the first cathode electrode is for the front light emitting, the second cathode electrode is for the bottom light emitting.

       The first cathode electrode is a conductive material having a low work function, and the second cathode deposits a conductive material having a high reflectance and a low work function.

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

5A to 5I are views illustrating a process of manufacturing a bidirectional organic EL display element according to the present invention, FIG. 6 is a pixel circuit diagram of a bidirectional organic EL display according to the present invention, and FIG. 7 is a diagram of a bidirectional organic EL display according to the present invention. Pixel structure plan view.

First, as shown in FIG. 5A, a semiconductor material 22, such as polycrystalline silicon, to be used as an active layer of a thin film transistor is formed and patterned on a transparent substrate 21 such as glass. After the gate insulating film 23 is formed thereon, the gate electrode 24 is deposited and then patterned. In addition, an impurity such as B or P is implanted into a portion of the semiconductor layer 22 and heat-treated to form source-drain regions 22a and 22c of the thin film transistor.

The interlayer insulating layer 25 is deposited on the gate electrode 24, and a portion of the gate insulating layer 23 and the interlayer insulating layer 25 is etched on the source-drain regions 22a and 22c of the transistor to form a contact hole. After forming, the metal is deposited and patterned to form the electrode line 26.

Next, as shown in FIG. 5B, a transparent, high work function value, such as ITO, is deposited on the first pixel electrode 27 for bottom emission and patterned.

5C, a planarization film 28 is formed on the metal line 26 and the first pixel electrode 27 to planarize the entire surface, and then partially planarize the metal electrode 26 on the drain region 22c. The film 28 is etched away to form the contact holes 29.

Next, as shown in FIG. 5D, the anode electrode 30, which is the second pixel electrode for top emission, is deposited and patterned with a conductive film having high reflectance and work function values such as Cr, Al, Mo, Ag, and Au. .

Next, a portion of the formed flattening film on the formed first light emitting anode 27 is removed to expose a portion of the first anode electrode (FIG. 5E).

As shown in FIG. 5F, the insulating layer 31 is formed to cover the edge of the second anode electrode 30 for top emission.

Subsequently, as shown in FIG. 5G, the hole injection layer 32, the hole transport layer 33, the red light emitting layer 34, and the electron transport layer may be disposed on the first and second anode electrodes 27 and 30 for back emission and top emission. 35) and organic substances, such as the electron injection layer 36, are formed in order.

Next, aluminum is deposited by several nm with the common electrode first cathode electrode, Ag is deposited by several nm to 15 nm, metal such as Mg: Ag is deposited by several nm to 15 nm, or a conductive material having a low work function is formed. Thus, the first cathode electrode 37 for top emission is formed (FIG. 5H).

In this case, the first cathode electrode is formed in all pixel areas as the common electrode.

Next, as shown in FIG. 5I, the front emission area is covered with the shadow mask 38, and then a conductive material having a high reflectance and a low work function, such as aluminum, is deposited on the organic material of the bottom emission area to form the second cathode electrode 39 for back emission. Form.

After forming a protective film 40 for protecting the formed organic material layer from oxygen or moisture by a process, although not shown in the drawing, a dual active driving organic EL panel is completed by attaching a protective cap using a sealant and a transparent substrate. do.

As described above, the present invention enables the manufacture of a display of a new concept in which an image can be viewed from both sides by simultaneously implementing a bottom emission type and a top emission type on the same substrate. It also has a very high effect.

In addition, the present invention can manufacture a device with high efficiency, and thus, there is an effect that the fabrication of an organic EL display device having low power consumption and long life can be obtained.                     

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (10)

In an organic EL display element in which a pixel driver is formed on a substrate to emit light, A bidirectional organic EL display element comprising a pixel electrode and a common electrode for back emission, and a pixel electrode and a common electrode for front emission respectively formed on the pixel driving region. delete Forming a pixel driver on the substrate; Forming a first anode electrode for back emission on the pixel driver; Forming a second anode electrode for front emission on the pixel driver and the first anode electrode; Forming an insulating film to expose a portion of the first anode electrode and to cover the second anode electrode, and sequentially forming a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer; Forming a first cathode electrode on an entire area of the light emitting layer; And covering the first cathode electrode region with a shadow mask to form a second cathode electrode. delete The method of claim 4, wherein And the first anode electrode for back emission is a transparent conductive film having a high work function. The method of claim 4, wherein And the second anode electrode for top emission is a conductive film having a high reflectance and a work function. The method of claim 6 And the second anode electrode uses one of Cr, Al, Mo, Ag, and Au. The method of claim 3, wherein And said first cathode electrode is for top emission and the second cathode electrode is for bottom emission. The method of claim 8, And said first cathode electrode forms a conductive material having a low work function. The method of claim 8, And the second cathode deposits a conductive material having a high reflectance and a low work function.

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