KR20150002996A - Method for fabricating Organic Electroluminescence Device and the Organic Electroluminescence Device fabricated by the method - Google Patents

Abstract

Disclosed are a method for manufacturing an organic electroluminescence device and an organic electroluminescence device manufactured by the same. The method for manufacturing an organic electroluminescence device according to the present invention comprises the steps of: forming a gate electrode on a first substrate; forming source and drain electrodes on the gate electrode; forming a first electrode to be connected to the drain electrode; forming a photosensitive resin layer on the first electrode; positioning a mask on the photosensitive resin layer; and forming an organic bank layer to expose a part of the first electrode by exposing and developing the photosensitive resin layer. A reflective pattern is formed at the same time in the step of forming the gate electrode or in the step of forming the source and drain electrodes.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of fabricating an organic electroluminescent device and an organic electroluminescent device fabricated by the method.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device, and more particularly, to a method of manufacturing an organic electroluminescent device capable of improving brightness uniformity and panel reliability and an organic electroluminescent device manufactured by the method.

An organic electroluminescence device (OLED) is a device that emits light when an exciton formed by the combination of electrons injected into the organic light emitting layer and holes is dropped from the excited state to the ground state.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing a band diagram for explaining the principle of light emission of a general organic electroluminescent device. FIG.

1, a typical organic electroluminescent device includes an anode 1, a cathode 7, a hole transport layer 3, an organic light emitting layer 4, and an electron transport layer 5 ).

In order to more efficiently inject holes and electrons, a hole injection layer 2 positioned between the anode 1 and the hole transport layer 3, and an electron injection layer 3 located between the electron transport layer 5 and the cathode 7 Layer (6).

At this time, the holes injected from the anode 1 into the organic light emitting layer 4 through the hole injection layer 2 and the hole transport layer 3 and the holes injected from the cathode 7 into the electron injection layer 6 and the electron transport layer 5, The electrons injected into the organic light emitting layer 4 form an exciton 8. [ When the excitons 8 fall from the excited state to the ground state, they emit light.

With this principle, the organic electroluminescent device has a self-luminescent characteristic, and thus can be reduced in thickness and weight as compared with a liquid crystal display device. In addition, organic electroluminescent devices are considered to be the next generation display devices for mobile electronic devices because they exhibit high-quality characteristics such as low power consumption, high luminance, and high reaction speed. Further, since the manufacturing process of the organic electroluminescent device is simple, the production cost can be further reduced as compared with the conventional liquid crystal display device.

In forming an organic light emitting layer on a light emitting region of such an organic electroluminescent device, an inkjet printing method having a simple process and low manufacturing cost has recently been used. Specifically, the organic light emitting solution of the ink type is directly dropped by the light emitting region.

2 is a cross-sectional view illustrating an organic electroluminescent device manufactured by a conventional method and an organic electroluminescent device manufactured by the method. More particularly, the present invention relates to a method for manufacturing an organic electroluminescent device using an ink-jet printing method and a cross-sectional view for explaining an organic electroluminescent device manufactured by the method.

Referring to FIG. 2, a conventional method of fabricating an organic electroluminescent device 100 includes forming an array portion including a thin film transistor T on a first substrate 101, forming a planarization layer Forming an inorganic insulating layer 132 covering an edge of each of the first electrodes 131, and forming a second electrode 131 on the planarization layer 121, And forming an organic bank layer 133 located on the inorganic insulating layer 132. Then, ink is supplied to each of the regions partitioned by the organic bank layer 133 to form the organic light emitting layer 134. [

However, in the step of forming the organic bank layer 133, an unidentified residual film 150 often occurs, thereby causing defective spreading of the ink.

3A and 3B are cross-sectional views illustrating a method of forming an organic bank layer in a conventional method of manufacturing an organic electroluminescent device according to the related art. Sectional views for explaining the reason why an unconfirmed residual film 150 is formed in forming the organic bank film 133 according to the prior art.

3A and 3B, a conventional method of forming the organic bank film 133 includes forming a positive or negative photosensitive resin film on the upper surface of the first electrode 131 and the inorganic insulating film 132 And exposing and developing a predetermined portion of the photosensitive resin film.

3A, when a positive photosensitive resin film is formed, a mask 160a having an opening corresponding to a partial area of the first electrode 131 is placed on the photosensitive resin film and then exposed.

However, the edge region of the opening portion of the mask 160a is relatively less exposed than the central region. Accordingly, an unrecognized residual film 150 is generated in the edge region of the opening.

3B, when a negative type photosensitive resin film is formed, a mask 160b having an opening corresponding to the region of the organic bank film 133 is placed on the photosensitive resin film and exposed.

At this time, the edge region of the opening receives back exposure from the exposure system stage (not shown). Therefore, the exposure amount is relatively larger than the central area. As a result, an undetermined residual film 150 is generated in the edge region of the opening.

These unidentified residual films 150 cause defective spreading of the ink material, resulting in lowering of uniformity of luminance and lowering of reliability of the panel.

A further object of the present invention is to provide a method of manufacturing an organic electroluminescent device with improved brightness uniformity and panel reliability, and an organic electroluminescent device manufactured by the method.

According to an aspect of the present invention, there is provided a method of manufacturing an organic electroluminescent device. The method of fabricating an organic electroluminescent device includes the steps of forming a gate electrode on a first substrate, forming source and drain electrodes on the gate electrode, forming a first electrode connected to the drain electrode, Forming a photosensitive resin film on the first electrode, positioning a mask on the photosensitive resin film, and exposing and developing the photosensitive resin film to form an organic bank film exposing a part of the first electrode, , A step of forming the gate electrode, or a step of forming the source and drain electrodes.

According to another aspect of the present invention, there is provided an organic electroluminescent device. The organic electroluminescent device includes a gate electrode, a source and a drain electrode formed on the gate electrode, a first electrode connected to the drain electrode, an organic bank film formed on the first electrode, And a second electrode formed on the organic light emitting layer. The organic light emitting device further includes a reflection pattern formed on the same layer as the gate electrode or the source and drain electrodes.

The present invention improves the spreadability of the ink material to ensure the uniformity of the brightness of the organic electroluminescent device and the reliability of the panel.

In addition, the present invention can improve the cost efficiency of the organic electroluminescent device manufacturing process by using the existing process.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram showing a band diagram for explaining the principle of light emission of a general organic electroluminescent device. FIG.
2 is a cross-sectional view illustrating an organic electroluminescent device manufactured by a conventional method and an organic electroluminescent device manufactured by the method.
3A and 3B are cross-sectional views illustrating a method of forming an organic bank layer in a conventional method of manufacturing an organic electroluminescent device according to the related art.
FIGS. 4 to 10 are cross-sectional views for explaining a method of fabricating an organic electroluminescent device according to an embodiment of the present invention.
7A and 7B are cross-sectional views illustrating a method of forming an organic bank film in a method of manufacturing an organic electroluminescent device according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings showing a method of manufacturing an organic electroluminescent device and an organic electroluminescent device manufactured by the method. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of an apparatus may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

FIGS. 4 to 10 are cross-sectional views for explaining a method of fabricating an organic electroluminescent device according to an embodiment of the present invention.

Referring to FIG. 4, a buffer layer 202 is formed on the entire surface of the first substrate 201. The first substrate 201 may be formed of any one selected from conventional glass, plastic, and polymer, but is not limited thereto. In the case of a flexible substrate that has recently been attracting attention, a transparent substrate made of a transparent material such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene sulfone (PES), transparent polyimide (PI), polyarylate (PCO), polymethyl methacrylate (PMMA), crosslinking type epoxy, crosslinking type urethane, and the like.

The buffer layer 202 prevents the impurities of the first substrate 201 from diffusing when the active layer 210 or the organic light emitting layer 234 (see FIG. 8) is formed. An example of the buffer layer 202 is a silicon nitride layer or a layer in which silicon nitride and silicon oxide are stacked. Of course, this buffer layer 202 may be omitted as needed.

A thin film transistor T is formed on the buffer layer 202. The thin film transistor T includes an active layer 210, a gate electrode 215 and source / drain electrodes 217 and 218 (see FIG. 5) formed on the buffer layer 202.

The active layer 210 includes a source region 211 and a drain region 213 and a channel region 212 connecting them. A gate insulating layer 214 is formed on the entire surface of the first substrate 201 on which the active layer 210 is formed. A gate electrode 215 is formed on the gate insulating layer 214 at a position corresponding to the channel region 212 of the active layer 210.

In the case of the present invention, the reflection patterns 215 'and 215''are formed together when the gate electrode 215 is formed. Therefore, the reflection patterns 215 'and 215''are formed of the same material in the same layer as the gate electrode 215. The gate electrode 215 is made of metal, for example, a metal selected from MoW, Al, Cr, and Al / Cr. However, in the present invention, it is preferable to use metals having reflective properties such as Mo / Al / Mo, Mo / Al, Al, and Cu.

The positions where the reflection patterns 215 'and 215' 'are formed correspond to the edge regions of the organic bank film 233 (see FIGS. 7A and 7B) to be formed later. Specifically, it is formed with a width of about 5 to 10 mu m inward from the edge of the organic bank film 233 (see Figs. 7A and 7B) to be formed later.

The reflective patterns 215 'and 215' 'reflect or block the light in the organic bank layer 233 (see FIGS. 7A and 7B) to prevent the occurrence of an unidentified residual film due to an unbalanced amount of exposure.

The reflective patterns 215 'and 215' 'may be formed at the later step of forming the source / drain electrodes 217 and 218 (see FIG. 5) instead of forming the gate electrode 215. In this case, the reflection pattern is formed of the same material on the same layer as the source / drain electrodes 217 and 218 (see FIG. 5). However, as described above, it is preferable to use metals having reflective properties such as Mo / Al / Mo, Mo / Al, Al, and Cu.

The present invention utilizes the conventional gate electrode 215 formation process or the source / drain electrodes 217 and 218 (see FIG. 5) without additional mask process for forming the reflective patterns 215 'and 215''.

Referring to FIG. 5, a gate electrode 215 and reflection patterns 215 'and 215' 'are formed on a gate insulating film 214, and then an interlayer insulating film 216 is formed. The interlayer insulating layer 216 is formed on the entire surface of the first substrate 201 so as to cover the gate electrode 215 and the reflective patterns 215 'and 215' '.

A first contact hole is formed in the gate insulating film 214 and the interlayer insulating film 216. The source region 211 and the drain region 213 of the active layer 210 are exposed through the first contact hole. The source electrode 217 and the drain electrode 218 are electrically connected to the exposed source region 211 and the drain region 213, respectively. The source electrode 217 and the drain electrode 218 may be formed of a metal such as Ti / Al or Ti / Al / Ti. The thin film transistor T is completed by forming the source electrode 217 and the drain electrode 218.

However, the present invention is not limited to this. The structure of all thin film transistors known so far, for example, an inverted coplanar structure, a zigzag structure (see, for example, a staggered structure, an inverted staggered structure, or an equivalent structure thereof.

After the thin film transistor T is completed, a protective film 220 and a planarization film 221 are sequentially formed on the entire surface of the first substrate 201.

Referring to FIG. 6, a second contact hole 222 exposing a portion of the drain electrode 218 is formed on the passivation layer 220 and the planarization layer 221 formed on the entire surface of the first substrate 201.

A first electrode 231 connected to the drain electrode 218 through the second contact hole 222 is formed on the planarization layer 221.

When the first electrode 231 is an anode, ITO (indium tin oxide), ITO (indium tin oxide) / Ag, ITO (indium tin oxide) / Ag / ITO, ITO (indium tin oxide) / IZO (Indium Zinc Oxide), and the like. However, the material of the first electrode 231 is not limited in the present invention. ITO (Indium Tin Oxide) is a transparent conductive film having a small hole injection barrier in the organic light emitting layer 234 (see FIG. 8).

Then, an inorganic insulating film 232 covering the edge of the first electrode 231 is formed. A part of the first electrode 231 is exposed through the opening of the inorganic insulating film 232. The shape of the opening may be a rectangle, an ellipse, a circle, an ellipse, or the like in plan view. The inorganic insulating film 232 prevents the electric field from concentrating on the edge of the first electrode 231. The inorganic insulating film 232 may be omitted in some cases.

7A and 7B are cross-sectional views illustrating a method of forming an organic bank film in a method of manufacturing an organic electroluminescent device according to the present invention.

7A and 7B, the organic bank film 233 may be formed by forming a positive or negative photosensitive resin film on the upper surface of the first electrode 231 and the inorganic insulating film 232, And exposing and developing a predetermined portion of the film.

Referring to FIG. 7A, when a positive photosensitive resin film is formed, a mask 260a having an opening corresponding to a partial area of the first electrode 231 is placed on the photosensitive resin film and exposed.

At this time, the photosensitive resin film portion corresponding to the edge region of the opening is double-exposed. And the reflection patterns 215 'and 215''reflect the incident light upon exposure to the photosensitive resin film again. Therefore, it is possible to suppress the occurrence of an unidentified residual film due to the insufficient exposure amount in the edge region of the opening.

7B, when a negative type photosensitive resin film is formed, a mask 260b having an opening corresponding to the region of the organic bank film 233 is placed on the photosensitive resin film and exposed.

At this time, the portion of the photosensitive resin film corresponding to the edge region of the opening is suppressed in the back exposure. Since the reflective patterns 215 'and 215 " reflect light due to back exposure.

Referring to FIG. 8, ink is supplied to each of the regions partitioned by the organic bank film 233. An organic light emitting layer 234 is formed. The organic bank film 233 makes the boundary between the red, green and blue pixels clear so that the light emitting boundary region between the pixels becomes clear.

When the inorganic insulating film 232 is omitted, the organic bank film 233 electrically separates the first electrodes (not shown) of adjacent pixels from each other. In this case, the organic bank layer 233 may be formed of polyimide or the like.

When the inorganic insulating film 232 is formed, the inorganic insulating film 232 electrically separates the first electrode (not shown) of the adjacent pixel. At this time, the organic bank layer 233 serves to partition a region to be supplied with ink.

Referring to FIG. 9, a second electrode 235 covering the organic light emitting layer 234 and the organic bank layer 233 is formed.

Meanwhile, the organic light emitting layer 234 includes an emission layer (EML) that emits electrons and holes when excited to form excitons, an electron transport layer (ETL) And a hole transport layer (HTL) for appropriately adjusting the moving speed of the HTL. In addition, an electron injection layer (EIL) for improving the injection efficiency of electrons is formed in the electron transport layer, and a hole injection layer (HIL) for improving the injection efficiency of holes is formed in the hole transport layer .

When the second electrode 235 is a cathode, it may be selected from among Al, MgAg alloy, and MgCa alloy, but is not limited thereto.

The first electrode 231, the organic light emitting layer 234, and the second electrode 235 are sequentially formed in this manner to complete the light emitting portion 240.

When a voltage is applied between the first electrode 231 and the second electrode 235, electrons generated from the second electrode 235 and holes generated from the first electrode 231 move toward the organic light emitting layer 234 do . Accordingly, electrons and holes supplied to the organic light emitting layer 234 collide and recombine to generate light. The first electrode 231 is an anode and the second electrode 235 is a cathode as in a general case.

Referring to FIG. 10, a second substrate 320 is bonded to a first substrate 201 on which a light emitting unit 240 is formed. The first and second substrates 201 and 320 are bonded together through a sealing material 310. Thus, the organic electroluminescent device according to the present invention is completed.

One side of the second substrate 320 facing the first substrate 201 is removed by a cutting process. (Not shown) on the first substrate 201 to the outside. A driver integrated circuit or a flexible printed circuit (FPC) is electrically connected to the pad portion (not shown) through a subsequent process

101, 201: a first substrate 132, 232: an inorganic insulating film
131, 231: First electrode 134, 234: Organic light emitting layer
133, 233: organic bank film 215 ', 215 ": reflection pattern
160a, 160b, 260a, 260b: mask 310: sealing material
320: second substrate

Claims (6)

Forming a gate electrode on the first substrate;
Forming source and drain electrodes on the gate electrode;
Forming a first electrode connected to the drain electrode;
Forming a photosensitive resin film on the first electrode;
Positioning a mask on the photosensitive resin film; And
And exposing and developing the photosensitive resin film to form an organic bank film exposing a part of the first electrode,
Wherein a reflective pattern is simultaneously formed in the step of forming the gate electrode or the step of forming the source and drain electrodes.
The method according to claim 1,
Wherein the reflective pattern comprises at least one of Mo / Al / Mo, Mo / Al, Al, and Cu.
The method according to claim 1,
Wherein the reflection pattern is formed to have a constant width from the edge of the organic bank film to the inside of the opening of the organic bank film.
A gate electrode;
Source and drain electrodes formed on the gate electrode;
A first electrode connected to the drain electrode;
An organic bank film formed on the first electrode;
An organic light emitting layer formed in a region partitioned by the organic bank film;
And a second electrode formed on the organic light emitting layer,
And a reflective pattern formed on the same layer as the gate electrode or the source and drain electrodes.
5. The method of claim 4,
Wherein the reflection pattern comprises at least one of Mo / Al / Mo, Mo / Al, Al and Cu.
5. The method of claim 4,
Wherein the reflection pattern has a constant width from an edge of the organic bank film toward an inside of the opening.

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