KR102455578B1 - Luminescence dispaly panel - Google Patents

Abstract

The present invention uses a spherical spacer to prevent an organic layer from being formed on the contact surface between the spherical spacer and the bank layer, thereby solving the peeling phenomenon of the organic layer that occurs when implementing a foldable display and simultaneously removing foreign substances from the contact surface between the FMM and the spacer. To a minimized light emitting display panel, the light emitting display panel according to the present invention has a configuration including an organic layer including a light emitting layer between a first electrode and a second electrode positioned on a substrate, and a light emitting region on the first electrode It further includes a bank insulating film including organic holes defining a spherical spacer made of a hydrophobic polymer material or conductive nanoparticles coated with a hydrophobic polymer material on the bank insulating film.

Description

Luminescent display panel {LUMINESCENCE DISPALY PANEL}

The present invention relates to a light emitting display panel, and more particularly, to a light emitting display panel that can be manufactured by providing a spherical spacer to prevent peeling of an organic layer and prevent damage to an organic layer during an organic layer deposition process.

A video display device that implements various information on a screen is a key technology in the information and communication era, and is developing in the direction of thinner, lighter, more portable and high-performance. Accordingly, as a flat panel display capable of reducing the weight and volume, which are disadvantages of a cathode ray tube (CRT), an organic electroluminescent display (OLED) that displays an image by controlling the amount of light emitted by an organic light emitting layer is in the spotlight. OLED is a self-luminous device using a thin light emitting layer between electrodes, and has the advantage of being able to thin it like paper.

In an active matrix OLED (AMOLED), pixels composed of three color (R, G, B) sub-pixels are arranged in a matrix to display an image. Each sub-pixel includes an organic electroluminescence (OEL) cell and a cell driver for independently driving the OEL cell.

The OEL cell consists of a first electrode connected to the cell driver, a bank insulating film having an organic hole exposing the first electrode, an organic layer including a light emitting layer positioned on the first electrode, and a second electrode formed on the organic layer. do. In this case, a spacer is provided on the bank insulating layer.

The cell driver includes at least two thin film transistors and a storage capacitor connected between a gate line for supplying a scan signal, a data line for supplying a video data signal, and a common power line for supplying a common power signal to drive the OEL cell. do.

Recently, various types of foldable displays using OLED have been proposed. However, in the case of the conventional OLED, the adhesive strength of the organic layer including the light emitting layer is weak, and there is a problem in that the organic layer is peeled off in the vicinity of the folded region.

In order to solve the above problem, the applicant has applied for an OLED device having an inverted spacer in which the shape of the spacer is improved to an inverted trapezoidal shape.

However, in the OLED device having the inverse spacer, the contact area between the inverse spacer and the fine metal mask (FMM) used to form the OLED increases as the upper contact area increases, and the contact area between the FMM and the inverse spacer increases. The foreign material caused defects in the OLED device.

The present invention has been devised to solve the above problems, and by applying a spherical spacer to prevent the organic layer from being formed on the contact surface between the spherical spacer and the bank layer, the organic layer peeling phenomenon that occurs when implementing a foldable display is solved and at the same time as the FMM. An object to be solved is to provide an OLED device that minimizes foreign substances generated on the contact surface between the spacer and the spacer.

In order to solve the above problems, an organic light emitting display panel according to the present invention has a configuration including an organic layer including a light emitting layer between a first electrode and a second electrode positioned on a substrate, and a light emitting area is defined on the first electrode and a bank insulating film including organic holes, and a spherical spacer made of a hydrophobic polymer material or conductive nanoparticles coated with a hydrophobic polymer material on the bank insulating film.

The organic light emitting display panel according to the present invention may include both the spherical spacer and the positive spacer on the bank insulating layer. In this case, the height of the positive spacer is higher than the height of the spherical spacer.

In the organic light emitting display panel according to the present invention, when the organic layer is formed, the FMM is in contact with the upper portion of the spherical spacer, thereby improving the peeling phenomenon of the organic layer occurring in the foldable display, and at the same time, the contact between the FMM and the spherical spacer is higher than when an inverted spacer is used. Since the area is small, it is also possible to improve the foreign body phenomenon caused by the contact between the FMM and the spacer. In addition, when only the spherical spacer is formed in the organic light emitting display panel according to the present invention, the photolithography process and the etching process for forming the positive spacer can be omitted, thereby reducing the process.

On the other hand, in the organic light emitting panel in which both the positive spacer and the spherical spacer are formed, since the positive spacer and the FMM are in contact and the spherical spacer and the FMM are not in contact, the contact area between the FMM and the spacer can be minimized and at the same time foldable It is possible to improve the peeling phenomenon of the organic layer occurring in the display.

1 is an equivalent circuit diagram of one pixel of a light emitting display panel according to the present invention.
2 is a cross-sectional view illustrating a structure of a light emitting display panel according to the present invention.
3 is a cross-sectional view illustrating a light emitting display panel including both a positive spacer and a spherical spacer.
4A to 4K are exemplary views for explaining a method of forming a light emitting display panel according to the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings and examples.

1 is an equivalent circuit diagram of one pixel of a light emitting display panel according to the present invention.

One pixel of the light emitting display panel shown in FIG. 1 includes a switch thin film transistor T1 connected to a gate line GL and a data line DL, a switch thin film transistor T1, a power supply line PL, and an OEL cell; and a driving thin film transistor T2 connected thereto, a storage capacitor C connected between the power supply line PL and a drain electrode of the switch thin film transistor T1, and an OEL cell connected to the driving thin film transistor T2. .

The gate electrode of the switch thin film transistor T1 is connected to the gate line GL, the source electrode is connected to the data line DL, and the drain electrode is connected to the gate electrode and the storage capacitor C of the driving thin film transistor T2. . The source electrode of the driving thin film transistor T2 is connected to the power supply line PL, and the drain electrode is connected to any one of the electrodes of the OEL cell. The storage capacitor C is connected between the power line PL and the gate electrode of the driving thin film transistor T2 .

The switch thin film transistor T1 is turned on when a scan pulse is supplied to the gate line GL, and supplies the data signal supplied to the data line DL to the storage capacitor C and the gate electrode of the driving thin film transistor T2 . do. The driving thin film transistor T2 controls the amount of light emitted from the OEL cell by controlling the current I supplied from the power line PL to the OEL cell in response to the data signal supplied to the gate electrode. And, even when the switch thin film transistor T1 is turned off, the driving thin film transistor T2 by the voltage charged in the storage capacitor C supplies a constant current I until the data signal of the next frame is supplied to the OEL Let the cell remain luminous.

The driving thin film transistor T2 is formed on the substrate 100 and the buffer layer 101 as shown in FIG. 2 , and a semiconductor layer 104 including a source region 109a and a drain region 109b on both sides thereof. A substrate including a gate insulating film 106 covering the semiconductor layer 104 , a gate electrode 102 positioned on the gate insulating film 106 corresponding to the semiconductor layer 104 , and the gate electrode 102 . A first protective layer 112 covering 100 and including contact holes 113 exposing source/drain regions 109a and 109b positioned on both sides of the semiconductor layer 104, and a contact hole ( and a source electrode 110 and a drain electrode 108 connected to the source/drain regions 109a and 109b through 113 .

The OEL cell includes a first electrode 116 on the first passivation film 112 and the second passivation film 114 covering the driving thin film transistor, and a bank insulating film 124 in which an organic hole exposing the first electrode 116 is formed. , an organic layer 118 including a spherical spacer 126 positioned on the bank insulating layer 124 , a light emitting layer formed on the first electrode 116 exposed through the organic hole, and a second electrode formed on the organic layer 118 . (120).

In this case, the spherical spacer 126 may be formed of a hydrophobic thermosetting resin or conductive nanoparticles coated with a hydrophobic polymer compound.

In this case, the first passivation layer 112 includes a contact hole 122 exposing the drain electrode 108 , and the first electrode 116 is connected to the drain electrode 108 of the thin film transistor through the contact hole 122 . do.

In this case, the substrate 100 is a flexible glass or polymer substrate, and the light emitting display panel according to the present invention may be manufactured as a flexible display or a foldable display.

The organic layer 118 includes an electron injection layer (EIL), an electron transport layer (ETL), a light emitting layer 206 , a hole transport layer (HTL), and a hole injection layer (HIL). ) are separated. In the light emitting layer, electrons from the cathode and holes from the anode are recombined and the generated excitons return to the ground state to emit light of a specific wavelength.

In this case, when the first electrode 116 is a cathode, the second electrode 120 is an anode, and when the first electrode 116 is an anode, the second electrode 120 is a cathode.

Meanwhile, the organic layer 118 and the second electrode 120 are also located on the spherical spacer.

The organic layer 118 and the second electrode 120 formed on the bank insulating layer 124 are not formed at the point where the spherical spacer 126 and the bank insulating layer 124 come into contact with each other. Also, the organic layer 118 is not formed. Accordingly, the organic layer 118 formed on the spherical spacer 126 and the organic layer 118 formed on the organic hole and bank insulating layer 124 are separated from each other at the point where the spherical spacer 126 and the bank insulating layer 124 contact each other.

When the spherical spacer 126 is formed on the bank insulating layer 124 as described above, the organic layer 118 is not deposited at the point where the spherical spacer 126 and the bank insulating layer 124 come into contact and on the side surface of the spherical spacer 126 . Therefore, the continuity of the organic layer 118 is partially broken. In addition, the barrier layer 130 is formed even in the region where the continuity of the organic layer 118 is broken, and the barrier layer 130 is formed between the contact point between the spherical spacer 126 and the bank insulating layer 124 and the spherical spacer 126 . It has an effect of fixing the organic layer 118 positioned under the barrier layer 130 due to excellent adhesion to the side surface.

Accordingly, in the light emitting display panel according to the present invention, the adhesion of the organic layer 118 is improved, and in particular, peeling of the organic layer 118 in the folding area can be prevented when a foldable panel is implemented.

In addition, since the light emitting display panel according to the present invention uses the spherical spacer 126, the contact area between the spacer and the fine metal mask (FMM) used to form the organic layer 118 is reduced compared to the case where the inverse spacer is used. small. Accordingly, when the spherical spacer 126 is used as in the present invention, it is possible to improve the peeling phenomenon of the organic layer occurring in the foldable display and at the same time minimize the foreign matter generated by the contact between the inverted spacer and the FMM.

3 is a cross-sectional view illustrating a light emitting display panel including both a positive spacer and a spherical spacer.

As shown in FIG. 3 , in the light emitting display panel according to the present invention, both the conventionally used spacers 128 and spherical spacers 126 may be formed in different regions on the upper portion of the bank insulating layer 124 . The conventional spacer is formed in a shape in which the width of the upper region is narrower than that of the lower region, and this is referred to as a 'positive spacer 128' for convenience.

At this time, the height of the positive spacer 128 is higher than that of the spherical spacer 126 . Therefore, the FMM used when forming the organic layer 118 is in contact with the positive spacer 128 .

In other words, in the light emitting display panel according to the present invention, the space between the light emitting display panel and the FMM is maintained by using the positive spacer 128 , and the organic layer 118 generated when the foldable display is implemented using the spherical spacer 126 . to prevent peeling.

4A to 4K are exemplary views for explaining a method of forming a light emitting display panel according to the present invention.

Referring to FIG. 4A , a buffer layer 101 is formed on a substrate 100 , and a semiconductor layer 104 is formed thereon. At this time, the buffer layer 101 and the semiconductor layer 104 are formed using a deposition method such as PECVD (Plasma Vapor Deposition). In addition, the semiconductor layer 104 is patterned through a photolithography process and an etching process.

Referring to FIG. 4B , the gate insulating layer 106 is formed by depositing an inorganic insulating material on the substrate 100 including the semiconductor layer 104 through a deposition method such as PECVD. A metal layer is deposited thereon through a method such as sputtering, and is patterned by photolithography and etching to form the gate electrode 102 .

Using the gate electrode 102 as a mask, impurities are implanted into both sides of the semiconductor layer 104 through an ion implantation method or the like, thereby forming source-drain regions 109a and 109b.

Referring to FIG. 4C , a first passivation layer 112 is formed on the substrate 100 including the gate electrode 102 and the semiconductor layer 104 through a deposition method such as PECVD. A contact hole 113 is formed in the first passivation layer 112 to expose the source/drain regions 109a and 109b through a photolithography process and an etching process.

Referring to FIG. 4D , a metal layer forming the source electrode 110 and the drain electrode 108 is deposited through a method such as sputtering. As the source/drain metal layer, molybdenum (Mo), molybdenum tungsten (MoW), copper (Cu), or the like is used. The source/drain metal layer is patterned by a photolithography process and an etching process to form a source/drain electrode pattern including the source electrode 110 and the drain electrode 108 .

Referring to FIG. 4E , a second passivation layer 114 including a contact hole 122 is deposited on the first passivation layer 112 including the source electrode 110 and the drain electrode 108 . In this case, the second passivation layer 114 may be formed of an organic insulating material such as acryl through a method such as spin coating or spinless coating. In addition, a contact hole 122 exposing the drain electrode 108 is formed in the second passivation layer 114 by a photolithography process and an etching process.

Referring to FIG. 4F , the first electrode 116 is formed on the second passivation layer 114 .

Specifically, the first electrode 116 may be formed on the second passivation layer 114 by a deposition method such as sputtering of an opaque conductive material such as aluminum (Al) or a transparent conductive material such as ITO. The first electrode 116 is connected to the drain electrode 108 of the thin film transistor through a contact hole 122 .

Referring to FIG. 4G , the bank insulating layer 124 including the organic hole 140 is formed on the substrate 101 on which the first electrode 122 is formed on the first electrode 116 .

On the bank insulating layer 124 and the organic hole 140 , an organic insulating layer for forming a spacer is formed by applying a photosensitive organic insulating material to the entire surface through a coating method such as spinless or spin coating in the same manner as the bank insulating layer 124 . . The positive spacers 128 are formed by patterning the organic insulating layer using a photolithography process and a patterning process.

When only the spherical spacer 126 is formed, the process of forming the positive spacer 128 may be omitted. That is, when only the spherical spacer 126 is formed, the photolithography process and the etching process for forming the positive spacer 128 can be omitted, so that the manufacturing process is reduced.

The process of forming the spherical spacer 126 will be described in detail with reference to FIGS. 4H and 4I.

The spherical spacer 126 is formed by spraying a hydrophobic thermosetting resin capable of forming the spherical spacer 126 in a state in which only the bank insulating film 124 is exposed using the mask 150, as shown in FIG. 4H, and then curing it. do.

In this case, the bank insulating layer 124 is made of a hydrophobic material, and the metal forming the first electrode 122 is made of a hydrophilic material. thereafter. The spherical spacer 126 may not be formed on the hydrophilic first electrode 122 , but may be formed only on the bank insulating layer 124 .

Meanwhile, the spherical spacer 126 may be formed using an electric field as shown in FIG. 4I . To this end, the spherical spacer 126 is formed using conductive nanoparticles 132 coated with a hydrophobic polymer compound 132 .

At this time, the mask 150 is a metal mask, an electric field is applied to the mask 150 so that the mask 150 is charged, and conductive nanoparticles 132 coated with a hydrophobic polymer compound 134 are applied to the mask 150 . By spraying, the nanoparticles 132 are attached to the mask 150 .

After that, the mask 150 is turned over to bring it close to the substrate 100 and the electric field applied to the mask 150 is removed. is formed

Since the spherical spacer 126 is coated with the hydrophobic polymer compound 134 , the spherical spacer 126 is not formed on the hydrophilic first electrode 122 , but is formed only on the bank insulating layer 124 .

After the spherical spacer 126 is formed as described above, as shown in FIG. 4J , the organic layer 126 and the second electrode 128 are formed on the substrate 101 on which the bank insulating film 124 including the organic hole 140 is formed. are formed sequentially.

Specifically, an organic layer 118 including an electron injection layer (EIL), an electron transport layer (ETL), a light emitting layer, a hole transport layer (HTL), and a hole injection layer (HIL) is formed on the first electrode 116 by a thermal evaporation method, sputtering method or a combination method thereof. When forming the organic layer 118 , an FMM is used, and the FMM is fixed and supported by a positive spacer 128 or a spherical spacer 126 .

At this time, since the FMM is in contact with the forward spacer 128 or only partially contacts the upper portion of the spherical spacer 126 , the occurrence of foreign matter is significantly reduced compared to the case of using the reverse spacer.

Thereafter, the second electrode 120 is formed on the substrate 100 on which the organic layer 118 is formed.

The second electrode 120 may be formed in at least one layer structure using a transparent conductive material or a metal material in the same manner as the organic layer 118 , or may be formed in a multilayer structure using a transparent conductive material and a metal material.

Referring to FIG. 4K , the barrier layer 130 is formed on the second electrode 120 . The barrier layer 130 has a structure in which at least one inorganic layer 127 and an organic layer 129 are crossed and stacked, and may be formed by a method such as Atomic Layer Deposition (ALD).

An upper substrate (not shown) may be further included on the upper barrier layer 130 , but the upper substrate may not be provided.

As described above, in the organic light emitting display panel according to the present invention, the spherical spacer 126 or the positive spacer 128 and the spherical spacer 126 are formed, and when the organic layer 118 is formed, the FMM is the positive spacer 128 or spherical spacer. By making contact with the upper portion of the spacer 126 , the peeling phenomenon of the organic layer 118 occurring in the foldable display is improved, and at the same time, the contact area between the FMM and the forward spacer 128 or the spherical spacer 126 is better than when the reverse spacer is used. Since this is small, it is also possible to improve the foreign body phenomenon caused by the contact between the FMM and the spacer.

On the other hand, when both the positive spacer 128 and the spherical spacer 126 are formed, the contact with the FMM occurs only in the positive spacer 128 , so that it is possible to minimize the foreign matter phenomenon and improve the peeling phenomenon of the organic layer 118 . can

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is known in the art to which the present invention pertains that various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention. It will be clear to those who have the knowledge of

100: substrate 101: buffer layer
102: gate electrode 104: semiconductor layer
106: gate insulating films 109a, 109b: source/drain regions
108: drain electrode 110: source electrode
112: first passivation layer 113, 122: contact hole
114: second passivation layer 116: first electrode
118: organic layer 120: second electrode
124: bank insulating film 126: spherical spacer
127: inorganic membrane 128: positive spacer
129: organic layer 130: barrier layer
132: conductive nanoparticles 134: hydrophobic polymer compound

Claims (6)

a first electrode positioned on the substrate;
a bank insulating film including organic holes exposing the first electrode on the substrate provided with the first electrode;
a spherical spacer positioned on the bank insulating film;
an organic layer including a first electrode exposed through the organic hole, a light emitting layer disposed on the bank insulating layer, and the spherical spacer;
and a second electrode positioned on the entire surface of the substrate including the bank insulating film and the organic layer,
The bank insulating layer is made of a hydrophobic material, and the spherical spacer is made of conductive nanoparticles coated with a hydrophobic polymer compound. The method of claim 1,
The organic light emitting display panel further comprising a barrier layer positioned on the entire surface of the substrate including the organic layer and the second electrode. The method of claim 1,
The spherical spacer is an organic light emitting display panel made of a hydrophobic thermosetting resin. delete The method of claim 1,
The organic light emitting display panel further comprising a positive spacer positioned on the bank insulating layer, which is a different region on the same plane as the region where the spherical spacer is positioned. 6. The method of claim 5,
The height of the positive spacer is higher than that of the spherical spacer.

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