KR102067895B1 - Organic light emitting diode and manufacturing method of the same - Google Patents

Abstract

The present technology relates to an organic light emitting diode and a method of manufacturing the same. The organic light emitting diode manufacturing method of the present technology comprises the steps of forming a polymer layer on a substrate; Etching the polymer layer to form a light extraction layer having a nanoscale random pattern; Forming a first electrode layer on the substrate on which the light extraction layer is formed; Forming an organic layer for generating light on the first electrode layer; And forming a second electrode layer on the organic layer.

Description

Organic light emitting diode and its manufacturing method {ORGANIC LIGHT EMITTING DIODE AND MANUFACTURING METHOD OF THE SAME}

The present invention relates to an organic light emitting diode and a method of manufacturing the same, and more particularly to an organic light emitting diode comprising a light extraction layer therein and a method of manufacturing the same.

The organic light emitting display reproduces an input image by using a phenomenon in which electrons and holes are combined in an organic material layer by flowing a current through a fluorescent or phosphorescent organic thin film to form an organic light emitting diode (OLED) of a pixel. .

In the organic light emitting device, light emitted from the organic light emitting layer passes through various elements of the device and comes out to the outside. Among the light emitted from the organic light emitting layer, light emitted from the organic light emitting layer is trapped inside the organic light emitting device and has low light extraction efficiency. There is.

1 is a view showing a cross section of a conventional organic light emitting device.

Referring to FIG. 1, a conventional organic light emitting device 1 includes a substrate 10, a first electrode layer 20, a hole injection / transport layer 30, a light emitting layer 40, an electron injection / transport layer 50, and a second. The electrode layer 60 is included. When power is supplied to each of the first electrode and the second electrode, electrons and holes are injected into the light emitting layer, and excitons to which the injected hole electrons are coupled transition from the excited state to the ground state to emit light.

In this case, the light generated in the light emitting layer may be totally reflected at the interface between the hole injection and transport layer and the first electrode layer, and thus may not flow to the outside, but may flow into the device. In addition, the light introduced into the first electrode layer may also be totally reflected at the interface between the first electrode layer and the substrate and at the interface between the first electrode layer and the hole injection / transport layer, and thus may not flow out to the outside, and may proceed horizontally along the first electrode layer. have. It is a mechanism that inhibits light efficiency.

In order to solve this problem, conventionally, an intermediate layer for compensating the refractive index between multilayer thin films is inserted, or an external auxiliary layer is formed to prevent total reflection using a microlens.

However, additionally inserted interlayers also suffer from total interfacial reflection due to different refractive indices with other layers. It also causes optical distortion problems.

The method using the micro lens is very difficult to install a separate lens on the substrate, and does not correspond to the smaller and smaller device scale.

The inventor of the present invention has completed the present invention after a long research and trial and error to solve these problems.

Embodiments of the present invention provide an organic light emitting diode and a method for manufacturing the same, including a light extraction layer therein and reducing light distortion.

On the other hand, other unspecified objects of the present invention will be further considered within the range that can be easily inferred from the following detailed description and effects.

An organic light emitting diode manufacturing method according to an embodiment of the present invention, forming a polymer layer on a substrate; Etching the polymer layer to form a light extraction layer having a nanoscale random pattern; Forming a first electrode layer on the substrate on which the light extraction layer is formed; Forming an organic layer for generating light on the first electrode layer; And forming a second electrode layer on the organic layer.

At least one of the first electrode layer, the organic layer, and the second electrode layer may be formed along the random pattern.

The polymer constituting the polymer layer may have a refractive index similar to that of the substrate.

The polymer constituting the polymer layer may be a high permeability polymer.

The light extraction layer forming step may be dry etching using a gas containing a fluorine atom together.

In the light extraction layer forming step, the surface of the polymer may be fluorinated by the fluorine atom to increase chemical resistance and heat resistance of the light extraction layer.

The first electrode layer forming step may be a high temperature heat treatment process.

In addition, the organic light emitting diode according to an embodiment of the present invention, the substrate; A light extraction layer having a nanoscale random pattern disposed on the substrate; A first electrode layer formed on the substrate on which the light extraction layer is formed; An organic layer formed on the first electrode layer and generating light; And a second electrode layer formed on the organic layer.

At least one of the first electrode layer, the organic layer, and the second electrode layer may be formed along the random pattern.

The light extraction layer may be a high-permeability polymer material similar in refractive index to the substrate.

The light extraction layer may comprise a fluorinated surface.

The first electrode layer may include ITO.

In addition, the organic light emitting diode according to an embodiment of the present invention, the substrate; A light extraction layer disposed on the substrate, the light extraction layer having a nanoscale random pattern similar in refractive index to the substrate; And an organic light emitting diode in which a first electrode layer, an organic layer, and a second electrode layer are sequentially formed on a substrate on which the light extraction layer is formed, wherein an upper surface of at least one of the first electrode layer, the organic layer, and the second electrode layer is formed. The first electrode layer may have a shape along a boundary line (random pattern line) in contact with the substrate on which the light extraction layer and the light extraction layer are formed.

The vertical height difference of the upper surface of the first electrode layer may be gentler than the vertical height difference of the random pattern line.

The present technology can provide an organic light emitting diode and a method of manufacturing the same, which can reduce light distortion due to total reflection and improve light efficiency.

In addition, the present technology can improve the external light efficiency by forming a light extraction layer inside the substrate to significantly reduce the total reflection and loss of light at the interface with the multilayer thin film inside the substrate.

1 is a view showing a cross section of a conventional organic light emitting device.
2 is a cross-sectional view showing the configuration of an organic light emitting diode according to an embodiment of the present invention.
3 is a diagram showing a random pattern line formed by the light extraction layer according to the embodiment of the present invention.
4A to 4E are diagrams sequentially illustrating a method of manufacturing an organic light emitting diode according to an embodiment of the present invention.
5A and 5B illustrate electron micrographs of random patterns obtained according to process conditions in an etching process according to an exemplary embodiment of the present invention.
6A to 6C illustrate a dry etching process for patterning a polymer layer according to an exemplary embodiment of the present invention.
7A and 7B illustrate optical and device characteristics of an organic light emitting diode manufactured according to an exemplary embodiment of the present invention.
The accompanying drawings show that they are illustrated as a reference for understanding of the technical idea of the present invention, thereby not limiting the scope of the present invention.

In the following, the most preferred embodiment of the present invention is described. In the drawings, the thickness and spacing are expressed for convenience of description and may be exaggerated compared to the actual physical thickness. In describing the present invention, well-known structures irrelevant to the gist of the present invention may be omitted. In adding reference numerals to the components of each drawing, it should be noted that the same components as much as possible, even if displayed on different drawings.

2 is a cross-sectional view showing the configuration of an organic light emitting diode 100 according to an embodiment of the present invention.

Referring to FIG. 2, the organic light emitting diode 100 according to the embodiment of the present invention is disposed on a substrate SUB, a light extraction layer LE disposed on the substrate SUB, and a substrate on which the light extraction layer is formed. The first electrode layer E1, the organic layer OL disposed on the first electrode layer, and the second electrode layer E2 disposed on the organic layer are included. The organic layer OL includes a hole injection / transport layer HL, a light emitting layer ML, and an electron injection / transport layer EL that are sequentially disposed from the bottom upward (ie, in the direction II shown in the drawing).

The substrate SUB may be made of silicon, glass, or the like. It is preferable to have light transmittance.

The light extraction layer LE is formed on the substrate SUB as a plurality of patterns (nano scale random patterns) (hereinafter, referred to as 'random patterns' for convenience of description) having an arbitrary shape.

The light extraction layer LE may be formed of a polymer material. It is preferably a polymer material having high permeability (eg, 80% or more transmittance). For example, it may be polymethylmethacrylate (PMMA).

The light extraction layer LE may have a refractive index similar to that of the substrate SUB. In one example, they may be equivalent. Thus, light generated from the organic layer is reduced to be reflected at the interface between the light extraction layer and the substrate.

Alternatively, the light extraction layer may have a slightly lower refractive index or slightly higher than the substrate. As an example, the substrate may have a refractive index having a difference within 0.2 from the substrate. If the refractive index of the substrate is 1.5, the refractive index of the light extraction layer may have a refractive index in the range of 1.3 ~ 1.7. Even with this small difference, the effect of reducing the light reflected at the interface can be expected.

In FIG. 2, for convenience of description, six random patterns of the light extraction layer are placed in the horizontal direction (that is, the I direction shown in the drawing) in the drawing, and they are shown to have the same height or width different from each other or slightly different. However, the present invention is not limited thereto, and fewer or six patterns may be formed at irregular heights and widths.

Further, as the random patterns of the light extraction layers are shown in the horizontal direction (I direction) in the drawing, the cross sections are respectively shown as rectangles (ie, six rectangles), but when viewed from the top to the bottom in the drawing (-II Looking in the direction), the planar shape may have a variety of shapes, such as circular, elliptical, polygonal. In addition, the planar shape is not limited thereto, and may be a cone shape, a cone shape, a parabola shape, or the like, and accordingly, may be variously represented as a cross-sectional triangle or a trapezoid.

The random patterns may be island shapes spaced apart from each other, as shown in the figure.

The height of each of the random patterns (the height in the II direction) may be approximately 1 nm to 1000 nm. The width (length in the I direction) of each of the random patterns may be approximately 1 nm to 1000 nm.

The first electrode layer E1 is disposed on the light extraction layer LE having the nanoscale random pattern.

The first electrode layer E1 may be formed using ITO as an electrode layer made of a transparent material. It may be formed using ITO / Ag / ITO or ITO / Al / ITO instead of ITO.

As described above, since the random patterns of the light extraction layer have an island shape, the first electrode layer E1 formed thereon directly contacts the substrate, and a random pattern is interposed therebetween. When the first electrode layer E1 is in direct contact with the substrate SUB, since there is no random pattern interposed therebetween, the first electrode layer is formed at a position h1 (see FIG. 3) corresponding to the thickness of its own deposition. do. When a random pattern is interposed between the first electrode layer E1 and the substrate SUB, it is formed at a position of the height h2 (see FIG. 3) that is increased by the thickness t (see FIG. 3) of the random pattern.

Accordingly, the first electrode layer E1 disposed on the substrate SUB on which the light extraction layer LE is formed is formed at an irregular height. It is formed with contour lines corresponding to the thicknesses of the random patterns.

More specifically, when there is a line (hereinafter referred to as a random pattern line) connecting a boundary line between the first electrode layer E1 and the substrate SUB on which the light extraction layer LE and the light extraction layer are formed, It can be seen that the electrode layer E1 is formed with contour lines along this random pattern line.

This random pattern line Lrp is shown in FIG. 3. Referring to FIG. 3, the light extraction layer LE, the substrate SUB on which the light extraction layer is formed, and the first electrode layer E1 formed thereon are illustrated by dotted lines. The boundary line between them (the boundary line where the first electrode layer is in contact with the substrate on which the light extraction layer and the light extraction layer are formed) is shown by a solid line. This solid line corresponds to the random pattern line Lrp.

That is, the upper surface S1 of the first electrode layer E1 is formed with contour lines along the random pattern line Lrp. The upper and lower surfaces of the first electrode layer also have upper and lower elevations according to the vertical elevations of the random pattern lines. In other words, the shape of the upper surface S1 of the first electrode layer E1 follows the random pattern line Lrp.

Here, as described above, since the light extraction layer has a refractive index almost similar to that of the substrate, it can be seen that the first electrode layer is raised on one material in terms of refractive index. The substrate and the light extraction layer, which are two materials having the same refractive index, become a new substrate as one base, and the first electrode layer is raised on the base. In short, the substrate on which the light extraction layer is formed forms one new substrate in terms of refractive index. And this one new board | substrate has the above-mentioned random pattern line, and, as mentioned later, increases external light efficiency.

Meanwhile, in the drawings, for convenience of description, the upper surface of the first electrode layer is similarly shown to have a height difference according to the height difference of the random pattern line, but since the first electrode layer is formed thicker than the light extraction layer, the random pattern line The elevation difference of R may be relatively weakly reflected on the upper surface of the first electrode layer, and may be formed more smoothly than shown. That is, the upper surface shape of the first electrode layer may be gentler than that shown. However, the increase in the external light efficiency according to the exemplary embodiment of the present invention may be reflected only on the upper surface of the first electrode layer as a general tendency of the height difference of the random pattern line.

Referring back to FIG. 2, an organic layer OL for generating light is formed on the first electrode layer E1. The organic layer may include a hole injection / transport layer HL, a light emitting layer ML, and an electron injection / transport layer EL sequentially stacked from the first electrode layer.

In addition, the second electrode layer E2 is formed on the organic layer. The second electrode layer may include a conductive material of opaque material. The second electrode layer may be formed of a reflective material to reflect the light emitted from the organic layer to transfer the light toward the substrate SUB.

The organic layer OL and the second electrode layer E2 may be sequentially formed on the first electrode layer in the same manner as the conventional organic light emitting device manufacturing method. However, the organic layer OL and the second electrode layer E2 according to the exemplary embodiment of the present invention are formed along the random pattern line Lrp.

That is, the organic layer OL may be formed with contour lines along the random pattern line Lrp. The upper surface shape of the organic layer OL may follow the random pattern line Lrp. This is because it is formed on the first electrode layer along the random pattern line. Each of the hole injection / transport layer HL, the light emitting layer ML, and the electron injection / transport layer EL constituting the organic layer OL is formed with a contour line along the random pattern line Lrp.

Similarly, the second electrode layer E2 may also be formed with contour lines along the random pattern line Lrp. The upper surface shape of the second electrode layer E2 may follow the random pattern line Lrp. This is because it is formed on the organic layer along the random pattern line.

Since the organic light emitting diode 100 according to the embodiment of the present invention having such a structure as a whole has a bent or uneven shape along a random pattern, the light generated in the light emitting layer ML is transferred to each organic layer OL and the electrode layers E1. , The angle of incidence to E2) can be varied, thereby significantly reducing the total reflection between layers. Improve external light efficiency.

Meanwhile, according to another embodiment of the present invention, a buffer layer for planarization may be applied. In this case, the layers formed after the buffer layer may be formed in a flat shape without following the random pattern line described above. For example, when the buffer layer is interposed between the organic layer and the second electrode layer, the second electrode layer may be formed as a flat layer without following a random pattern line. Alternatively, when the buffer layer is interposed between the organic layer and the first electrode layer, the organic layer may be formed as a flat layer without following a random pattern line. Likewise, when interposed between the light extraction layer and the first electrode layer, the layers after the buffer layer may be formed flat. However, as the number of layers along the random pattern line increases, the above-described external light efficiency improving effect may be increased. Therefore, the buffer layer is preferably applied according to the required external light efficiency improving condition.

4A to 4E are diagrams sequentially illustrating a method of manufacturing the organic light emitting diode 100 according to the embodiment of the present invention.

First, referring to FIG. 4A, a polymer layer 120 for forming a light extraction layer is formed on a substrate 110.

The substrate 110 may generally use a material used for manufacturing an organic light emitting diode.

The polymer layer 120 may use a high permeability polymer polymer.

The polymer layer may be formed on the substrate in an application manner. Various methods such as a spin coating method, a spray method, and a drop method may be applied.

The polymer layer has a plurality of patterns having an arbitrary shape, that is, the above-described random patterns through the subsequent etching process, the type, molecular weight, concentration, additives, etc. of the polymer are selected in consideration of the size and spacing of the random patterns. Can be.

Polymers Polymers can be selected from materials that have a similar or lower refractive index than the substrate to minimize reflection at the interface with the substrate. Polymer The polymer may serve to mitigate the difference in refractive index between the substrate and the first electrode layer between the substrate and the first electrode layer placed thereon.

Subsequently, referring to FIG. 4B, the polymer layer 120 deposited on the substrate 110 is dry etched to form a randomly arranged nanoscale polymer random pattern. A polymer pattern layer 120a having a random pattern forms the light extraction layer described above with reference to FIG. 2.

The dry etching process may apply a reactive ion etching (RIE) method. For example, the polymer layer formed on the substrate may be etched using the O ₂ plasma. Gas and energy can be adjusted according to the shape and density of the random pattern.

For example, another gas plasma may be used to obtain the random pattern shown on the left side of FIG. 5A or the random pattern shown on the right side of FIG. 5A. The density of the random patterns can be adjusted.

Alternatively, the reactive ion etching time may be applied differently to obtain a random pattern shown on the left side, a random pattern shown in the middle, or a random pattern shown on the right side. You can adjust the height of the random pattern.

According to an embodiment of the present invention, a gas containing fluorine (F) atoms may be used together in a dry etching process. This can control the chemical resistance and heat resistance by fluorination of the surface of the polymer. This is because when the halogen gas reacts with the polymer, a material such as Teflon may be formed.

More specifically, FIG. 6 shows a dry etching process for patterning a polymer layer according to an embodiment of the present invention.

When the substrate 110 and the polymer layer 120 are prepared as shown in FIG. 6A, dry etching is performed using a gas (PL + G) containing fluorine atoms together with plasma as shown in FIG. 6B.

In the dry etching process, the polymer is etched and simultaneously polymerized to form polymer pillars or polymer lumps as shown in the drawings, and some regions of the substrate are exposed to the outside.

At the same time, in the dry etching process, the polymer polymer may form a material having high heat resistance through the reaction of the polymer with the halogen group gas.

After the etching process, as shown in FIG. 5C, a polymer pattern layer 120a patterned into a nanoscale random pattern having high heat resistance is obtained.

As such, when the surface of the polymer pattern layer has chemical resistance and heat resistance, chemical and thermal stability may be improved in a subsequent high temperature subsequent heat treatment process (for example, an electrode layer forming process including ITO proceeded by sputtering or a TFT heat treatment process). Can have

That is, it is possible to prevent the random pattern from being damaged in a subsequent process and thus to more easily induce that a plurality of layers formed thereon are formed along the random pattern of the polymer pattern layer.

Referring again to FIG. 4C, the first electrode layer 130 is formed on the substrate 110 on which the polymer pattern layer 120a of the random pattern is formed. In one example, the first electrode layer is formed using ITO, ITO / Ag / ITO, or ITO / Al / ITO. The electrode layer including ITO may be deposited by a sputtering method of a heat treatment process of about 400 ℃. As described above, in the process of forming the first electrode layer corresponding to the high temperature heat treatment process, the polymer pattern layer may be thermally and chemically stable.

Subsequently, as shown in FIG. 4D, the organic layer 140 including the hole injection and transport layer 142, the light emitting layer 144, and the electron injection and transport layer 146 is sequentially formed on the first electrode layer 130. Thereafter, as shown in FIG. 4E, the second electrode layer 150 is formed on the organic layer 140.

Since the polymer pattern layer 120a has a nanoscale random pattern, the first electrode layer 130, the organic layer 140, and the second electrode layer 150 stacked thereon may be curved or uneven along the random pattern. Is formed.

This makes it possible to vary the angle at which light generated in the light emitting layer is incident on each organic layer and electrode layers, thereby significantly reducing the total reflection between each layer (by minimizing the light accumulation inside the multilayer film and the substrate). External light efficiency can be improved.

7 shows optical and device characteristics of an organic light emitting diode manufactured according to an embodiment of the present invention.

First, referring to FIG. 7A, compared to Comparative Example (Eagle XG) in which only thin glass is used as a substrate, embodiments in which a polymer pattern layer having a random pattern described above are formed thereon (NRES ~ 80nm, NRES ~ 280nm) are compared. It can be seen that the transmittance is almost similar to the example.

NRES ˜80 nm represents values measured for the embodiments in which the random pattern size was formed up to 80 nm, and NRES ˜80 nm represents values measured for the embodiments in which the random pattern size was formed up to 280 nm. Air is a reference value (100%) measured without a sample.

Referring to FIG. 7B, it can be seen that the device emission characteristics of the device (Device-2) to which the above-described random pattern is applied are improved compared to the device (Reference) that is not. It can be seen that the electroluminescence intensity is nearly doubled at approximately 520 nm.

Although the technical spirit of the present invention has been specifically recorded in accordance with the above-described preferred embodiments, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, one of ordinary skill in the art will appreciate that various embodiments are possible within the spirit of the present invention.

100: organic light emitting diode
SUB, 110: Substrate
LE, 120a: light extraction layer, polymer pattern layer
E1, 130: first electrode layer
HL, 142: hole injection and transport layer
ML, 144: emitting layer
EL, 146: electron injection and transport layer
OL, 140: organic layer
E2, 150: second electrode layer
120: polymer layer

Claims (14)

Forming a polymer layer on the substrate;
Etching the polymer layer to form a light extraction layer having a nanoscale random pattern;
Forming a first electrode layer on the substrate on which the light extraction layer is formed;
Forming an organic layer for generating light on the first electrode layer; And
Forming a second electrode layer on the organic layer;
The substrate is made of silicon or glass,
The polymer constituting the polymer layer is a high permeability polymer having a refractive index difference within 0.2 with the substrate,
The light extraction layer forming step is dry etching using a gas containing a fluorine atom together,
Forming the first electrode layer is deposited by sputtering of a high temperature heat treatment process using ITO, ITO / Ag / ITO or ITO / Al / ITO,
In the light extracting layer forming step, the surface of the polymer is fluorinated by the fluorine atom to form a Teflon material so that the nanoscale random pattern of the light extracting layer is chemical resistance and An organic light emitting diode manufacturing method which has heat resistance. The method of claim 1,
At least one of the first electrode layer, the organic layer, and the second electrode layer is formed along the random pattern. delete delete delete delete delete Board;
A light extraction layer having a nanoscale random pattern disposed on the substrate;
A first electrode layer formed on the substrate on which the light extraction layer is formed;
An organic layer formed on the first electrode layer and generating light; And
Including; a second electrode layer formed on the organic layer,
The substrate is made of silicon or glass,
The light extraction layer is a highly transparent polymer material having a refractive index of 0.2 or less with the substrate,
The light extraction layer includes a Teflon material formed by fluorination of the surface of the light extraction layer by the fluorine atom through a dry etching process using a gas containing a fluorine atom,
The first electrode layer includes ITO by being deposited by a sputtering method of a high temperature heat treatment process using ITO, ITO / Ag / ITO or ITO / Al / ITO,
The nanoscale random pattern of the light extraction layer has a chemical resistance and heat resistance in the process of forming the first electrode layer which is a subsequent high temperature heat treatment process by the formed Teflon material, the organic light emitting diode. The method of claim 8,
At least one of the first electrode layer, the organic layer and the second electrode layer is formed along the random pattern. delete delete delete Board;
A light extraction layer disposed on the substrate, the light extraction layer having a nanoscale random pattern similar in refractive index to the substrate; And
And an organic light emitting diode in which a first electrode layer, an organic layer, and a second electrode layer are sequentially formed on the substrate on which the light extraction layer is formed.
An upper surface of at least one of the first electrode layer, the organic layer, and the second electrode layer has a shape along a boundary line (random pattern line) in which the first electrode layer contacts a substrate on which the light extraction layer and the light extraction layer are formed.
The substrate is made of silicon or glass,
The light extraction layer is a highly transparent polymer material having a refractive index of 0.2 or less with the substrate,
The light extraction layer includes a Teflon material formed by fluorination of the surface of the light extraction layer by the fluorine atom through a dry etching process using a gas containing a fluorine atom,
The first electrode layer includes ITO by being deposited by a sputtering method of a high temperature heat treatment process using ITO, ITO / Ag / ITO or ITO / Al / ITO,
The nanoscale random pattern of the light extraction layer has a chemical resistance and heat resistance in the process of forming the first electrode layer which is a subsequent high temperature heat treatment process by the formed Teflon material, the organic light emitting diode. The method of claim 13,
The vertical height difference of the upper surface of the first electrode layer is gentler than the vertical height difference of the random pattern line.

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