KR20160093132A - Organic light emitting diode and organic light emitting diode display device having the same - Google Patents

Abstract

The present invention discloses an organic light emitting diode and an organic light emitting diode display device having the same. The organic light emitting diode and the organic light emitting diode display device having the same include a first electrode which comprises a first conductive layer, a second conductive layer which is arranged on the first conductive layer and made of a different material from that of the first conductive layer, and a third conductive layer which is arranged on the second conductive layer and is made of a different material from that of the second conductive layer; an organic light emitting layer on the first electrode; and a second electrode on the organic light emitting layer. So, transmittance can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device and an organic electroluminescent display device having the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device and an organic electroluminescent display device having the organic electroluminescent device, and more particularly, to an organic electroluminescent device and a organic electroluminescent display device having the same which can reduce a high transmittance and a resistance.

BACKGROUND ART [0002] The development of an information society has been accelerated due to the development of an information display device which is light and highly portable. A liquid crystal display (LCD), which is a typical flat panel display, has been commercialized to replace cathode ray tube display devices. Organic light emitting displays (OLEDs) Emitting Diode Display).

The organic light emitting display device requires no separate light source such as a backlight used in a liquid crystal display device, so that it can be realized as thin as compared with a liquid crystal display device and has excellent color reproducibility, thereby realizing a thinner and clearer image. In addition, the organic light emitting display device has a wide viewing angle, excellent contrast ratio, fast response time, and low power consumption.

Such an organic light emitting display device includes an organic electroluminescent device including an anode electrode, an organic light emitting layer, and a cathode electrode, and an exciton formed by combining holes and electrons in the organic light emitting layer, emitting display device that emits light while falling from an exited state to a ground state.

Since the organic light emitting display device which is a self-emission type display device does not require a separate light source, it can be driven at a low voltage, can be configured as a lightweight thin type, has high quality characteristics such as wide viewing angle, high contrast and fast response speed Which is attracting attention as a next generation display device.

As the anode electrode of the organic electroluminescent device, indium-tin-oxide (ITO) is mainly used. However, in the case of an organic electroluminescent device in which the anode electrode is made of only indium-tin-oxide (ITO), it is necessary to improve the light efficiency and color purity. Therefore, various studies have been carried out to increase the light efficiency and color purity, and a micro cavity effect has been used as means for increasing the light efficiency and color purity.

A part of the light emitted from the organic light emitting layer of the organic electroluminescent device using the micro cavity effect is reflected by the cathode electrode to be directed toward the anode electrode and the light reflected from the cathode electrode is reflected again from the anode electrode, Light which is repeatedly reflected between the electrodes is generated. That is, a micro cavity, which is a phenomenon in which light is repeatedly reflected between two layers separated by an optical length, and light of a specific wavelength is amplified by the constructive interference, is realized, thereby improving the light efficiency and transmittance have.

For this micro cavity effect, a structure is used in which a layer made of silver (Ag) is disposed under the indium-tin-oxide (ITO) which is an anode electrode so as to cause reflection at the cathode electrode side. However, there is a problem that the transmittance of the organic electroluminescent device is reduced by the layer made of silver (Ag).

An object of the present invention is to provide an organic electroluminescent device with improved transmittance and an organic electroluminescent display device having the same.

According to an aspect of the present invention, there is provided an organic electroluminescent device including the first conductive layer and the first conductive layer, And a first electrode formed on the second conductive layer and made of a different material from the second conductive layer, the organic electroluminescent layer on the first electrode, And a second electrode on the organic light emitting layer.

Here, the first conductive layer and the third conductive layer of the first electrode may be made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ), and the second conductive layer may be made of silver (Ag) . The work function of the first electrode is 6 eV to 6.3 eV.

The organic light emitting layer disposed on the first electrode may include a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer. At this time, the difference in the HOMO energy level between the first electrode and the hole transport layer of the organic light emitting layer may be 0.7 eV or less. The thickness of the first conductive layer and the third conductive layer may be 35 nm to 60 nm, and the thickness of the second conductive layer may be 10 nm to 15 nm.

The organic electroluminescent device and the organic electroluminescent display device having the organic electroluminescent device according to the present invention can improve the light efficiency and improve the conductivity and the transmittance by using the electrode of the triple layer. The organic electroluminescent device according to the present invention and the organic electroluminescent display device having the organic electroluminescent device according to the present invention can be manufactured by using a triple-layered electrode so that the work function of the first electrode is high, There is an effect that can be.

1 is a schematic view of an organic light emitting display device according to the present invention.
2 is a view illustrating an organic electroluminescent device according to the present invention.
3 is a cross-sectional view illustrating an organic light emitting display device according to the present invention.
4 is a graph showing the transmittance of the first electrode of the organic electroluminescent device according to the comparative example and the example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 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 the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The dimensions and relative sizes of the layers and regions in the figures may be exaggerated for clarity of illustration.

It will be understood that when an element or layer is referred to as being another element or "on" or "on ", it includes both intervening layers or other elements in the middle, do. On the other hand, when a device is referred to as "directly on" or "directly above ", it does not intervene another device or layer in the middle.

The terms spatially relative, "below," "lower," "above," "upper," and the like, And may be used to easily describe the correlation with other elements or components. Spatially relative terms should be understood to include, in addition to the orientation shown in the drawings, terms that include different orientations of the device during use or operation. For example, when inverting an element shown in the figures, an element described as "below" or "beneath" of another element may be placed "above" another element. Thus, the exemplary term "below" can include both downward and upward directions.

The terminology used herein is for the purpose of describing embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprise "and / or" comprising ", as used in the specification, means that the presence of stated elements, Or additions.

1 is a schematic view of an organic light emitting display device according to the present invention. Referring to FIG. 1, an organic light emitting display according to an exemplary embodiment of the present invention includes an organic electroluminescent device OL disposed on a substrate 100.

Though not shown in the figure, a thin film transistor electrically connected to the organic electroluminescent device OL may be disposed on the substrate 100. The organic electroluminescent device OL includes a first electrode 120, an organic light emitting layer 110, and a second electrode 115.

The first electrode 120 of the organic electroluminescent device OL may be an anode. Also, the first electrode 120 may be composed of multiple layers. In detail, the first electrode 120 of the organic electroluminescent device OL of the organic electroluminescence display device according to the present invention includes a first conductive layer 121, a second conductive layer 121 disposed on the first conductive layer 121, The conductive layer 122 may be a third conductive layer 123 disposed on the second conductive layer 122. Here, the second conductive layer 122 is made of a different material from the first conductive layer 121, and the third conductive layer 123 is made of a different material from the second conductive layer 122 . Accordingly, the micro cavity effect of the first electrode 120 can be improved.

More specifically, the first conductive layer 121 is made of tungsten oxide (WO _x ), the second conductive layer is made of silver (Ag), the third conductive layer 123 is made of tungsten oxide (WO _x ) ≪ / RTI > The first electrode 120 of the organic electroluminescent device OL includes a first conductive layer 121 made of molybdenum oxide MoO _x , a second conductive layer 121 disposed on the first conductive layer 121, And a third conductive layer 123 formed on the second conductive layer 122 and made of molybdenum oxide (MoO _x ).

The first conductive layer 121 and the third conductive layer 123 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) have a very high conductivity. Therefore, even when the thickness of the second conductive layer 122 made of silver (Ag) is reduced to increase the transmittance of the first electrode 120, the first electrode 120 can maintain high conductivity. Also, by reducing the thickness of the second conductive layer 122, the transmittance of the first electrode 120 can be improved.

The work function of the first electrode 120 may be between 6 eV and 6.3 eV. In detail, the work function of the third conductive layer 123 of the first electrode 120 may be 6 eV to 6.3 eV. The first electrode 120 has a work function of 6 eV to 6.3 eV to omit the hole injection layer (HIL) of the organic light emitting layer 110 to reduce the structure of the organic light emitting OL There is an effect that can be simplified.

The organic light emitting layer 110 of the organic electroluminescent device OL is disposed over the first electrode 120. The organic light emitting layer 110 may be composed of multiple layers in order to increase the light emitting efficiency. In detail, the organic light emitting layer 110 includes a hole transporting layer 111, an emission layer 112, an electron transporting layer 113, and an electron transporting layer 114. injection layer. As described above, the first electrode 120 has a high work function, so that the structure of the organic light emitting layer 110 can be simplified.

A second electrode 115 of the organic electroluminescent device OL is disposed on the organic light emitting layer 110. At this time, the second electrode 120 may be a cathode electrode. The second electrode 120 may be formed of lithium (Li), calcium (Ca), aluminum (Al), silver (Ag), magnesium (Mg), or an alloy thereof.

An organic electroluminescent display device according to the present invention includes a first conductive layer 121 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ), a second conductive layer 121 disposed on the first conductive layer 121, And a third conductive layer 123 disposed on the second conductive layer 122 and made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ). By including the first electrode 120 of the organic electroluminescent device OL, the transmittance and color purity of the organic electroluminescent device OL can be improved. Also, since the first electrode 120 has a high work function, the structure of the organic light emitting layer 110 can be simplified.

Next, the organic electroluminescent device according to the present invention will be described with reference to FIG. 2 is a view illustrating an organic electroluminescent device according to the present invention. 2, the organic electroluminescent device according to the present invention includes an organic light emitting layer 110 disposed between a first electrode 120 and a second electrode 115. In this case, the first electrode 120 may be an anode electrode, and the second electrode 115 may be a cathode electrode.

When a driving voltage is applied to the first electrode 120 and the second electrode 115, holes passing through the hole transport layer 111 and electrons passing through the electron transport layer 113 are moved to the light emitting layer 112 to form excitons And as a result, the light emitting layer 112 can emit visible light.

The first electrode 120 of the organic electroluminescent device may be formed of a triple layer. In detail, the first electrode 120 includes a first conductive layer 121, a second conductive layer 122 disposed on the first conductive layer 121, and a second conductive layer 122 disposed on the second conductive layer 122 And a third conductive layer 123. Here, the second conductive layer 122 is made of a different material from the first conductive layer 121, and the third conductive layer 123 is made of a different material from the second conductive layer 122 .

More specifically, the first electrode 120 includes a first conductive layer 121 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ), a second conductive layer 121 disposed on the first conductive layer 121, A second conductive layer 122 made of tungsten (Ag), a third conductive layer 123 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) disposed on the second conductive layer 122 Lt; / RTI >

The organic light emitting layer 110 is disposed over the third conductive layer 123 of the first electrode 120. The organic light emitting layer 110 may include a hole transporting layer 111, a light emitting layer 112, an electron transporting layer 113, and an electron injection layer 114.

Here, since the work function of the first electrode 120 is 6 eV to 6.3 eV, the hole injection layer of the organic light emitting layer 110 can be omitted. That is, the third conductive layer 123 of the first electrode 120 may be disposed in contact with the hole transport layer 111 of the organic light emitting layer 110.

In addition, the HOMO energy level of the first electrode 120 may be different from the HOMO energy level of the hole transport layer 111 by 0.7 eV or less. Accordingly, the first electrode 120 may serve as a hole injection layer. In detail, the HOMO energy level of the first electrode 120 is different from the HOMO energy level of the HOMO energy level of the first electrode 120 by 0.7 eV or less, so that the hole injection ability of the first electrode 120 can be improved have.

The thickness of the first conductive layer 121 and the third conductive layer 123 of the first electrode 120 may be 35 nm to 60 nm. When the thicknesses of the first conductive layer 121 and the third conductive layer 123 are less than 35 nm or more than 60 nm, the first electrode 120 is difficult to serve as a hole injection layer.

The thickness of the second conductive layer 122 of the first electrode 120 may be 10 nm to 15 nm. If the thickness of the second conductive layer 122 is less than 10 nm, the conductivity of the first electrode 120 may be degraded. If the thickness of the second conductive layer 122 is more than 15 nm, the transmittance of the first electrode 120 may be lowered.

The organic electroluminescent device of the organic light emitting display according to the present invention includes a first conductive layer 121 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) And a third conductive layer 122 disposed on the second conductive layer 122 and made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) 123, the structure of the organic light emitting layer 110 can be simplified.

Next, an organic light emitting display device according to the present invention will be described with reference to FIG. 3 is a cross-sectional view illustrating an organic light emitting display device according to the present invention. Referring to FIG. 3, the organic light emitting display according to the present invention includes a thin film transistor (Tr) and an organic electroluminescent device. Here, the thin film transistor Tr is connected to the first electrode 120 of the organic electroluminescent device, thereby driving the organic electroluminescent device.

The thin film transistor Tr includes a semiconductor layer 101, a gate insulating film 102, a gate electrode 103, a source electrode 105, and a drain electrode 106. The organic electroluminescent device in contact with the thin film transistor Tr includes a first electrode 120 having a triple-layer structure, a second electrode 115 opposed to the first electrode 120, And an organic light emitting layer 110 disposed between the first electrode 115 and the second electrode 115.

In detail, the semiconductor layer 101 is disposed on the substrate 100. The semiconductor layer 101 is composed of a source region 101a, a channel region 101b and a drain region 101c.

A gate insulating film 102 is disposed on a substrate 100 including the semiconductor layer 101. The gate insulating layer 102 has an effect of preventing impurities from penetrating into the semiconductor layer 101. A gate electrode 103 is disposed on the gate insulating film 102. In detail, the gate electrode 103 may be disposed so as to overlap the channel region 101b of the semiconductor layer 101. [

 The gate electrode 103 may be an alloy formed from copper (Cu), molybdenum (Mo), aluminum (Al), silver (Ag), titanium (Ti), tantalum (Ta) Further, although the single metal layer is shown in the drawing, at least two or more metal layers may be laminated.

An interlayer insulating film 104 is disposed on the gate electrode 103. The interlayer insulating film 104 has an effect of protecting the gate electrode 103. A contact hole exposing the source region 101b and the drain region 101c of the semiconductor layer 101 is formed in the interlayer insulating film 104 and the gate insulating film 102. [

A source electrode 105 and a drain electrode 106 are formed on the contact hole and the interlayer insulating film 104. The source electrode 105 and the drain electrode 106 are connected to the source region 101a and the drain region 101c of the semiconductor layer 101 by the contact holes. The source electrode 105 and the drain electrode 106 may be formed of copper (Cu), molybdenum (Mo), aluminum (Al), silver (Ag), titanium (Ti), tantalum (Ta) Alloy. Further, although the single metal layer is shown in the drawing, at least two or more metal layers may be laminated.

As described above, the thin film transistor Tr may be disposed on the substrate 100. A protective film 107 is disposed on the substrate 100 including the thin film transistor Tr. A planarization layer 108 is disposed on the substrate 100 including the protective layer 107. A contact hole exposing the drain electrode 108 is formed on the protective film 107 and the planarization film 108.

And the first electrode 120 of the organic electroluminescent device connected to the drain electrode 108 by the contact hole is disposed. The first electrode 120 includes a first conductive layer 121, a second conductive layer 122 disposed on the first conductive layer 121, a third conductive layer 122 disposed on the second conductive layer 122, Layer 123 as shown in FIG. Here, the second conductive layer 122 is made of a different material from the first conductive layer 121, and the third conductive layer 123 is made of a different material from the second conductive layer 122 .

In detail, the first electrode 120 includes a first conductive layer 121 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ), a second conductive layer 121 disposed on the first conductive layer 121, And a third conductive layer 123 formed on the second conductive layer 122 and made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) do.

The organic light emitting layer 110 of the organic electroluminescent device is disposed on the first electrode 120. In detail, the organic light emitting layer 110 is disposed over the third conductive layer 123 of the first electrode 120. The organic light emitting layer 110 may include a hole transporting layer 111, a light emitting layer 112, an electron transporting layer 113, and an electron injection layer 114.

The organic light emitting layer 110 may be formed by a vacuum deposition method or a solution process. For example, the organic light emitting layer 110 may be formed by various vacuum deposition methods such as evaporation or CVD (chemical vapor deposition). The organic light emitting layer 110 may be formed by ink-jet, spin coating, slot-die, dip coating, or the like. However, the method of forming the organic light emitting layer 100 is not limited thereto, and the organic light emitting layer 100 may be formed by a combination of the vapor deposition method or the solution process.

A second electrode 115 of the organic electroluminescent device is disposed on the organic light emitting layer 110. The second electrode 120 may be formed of lithium (Li), calcium (Ca), aluminum (Al), silver (Ag), magnesium (Mg), or an alloy thereof.

Here, the organic light emitting display according to the present invention displays an image in the form of a top emission method or a bottom emission method. When the organic light emitting display device is a bottom emission type, the visible light generated from the organic light emitting layer 110 is displayed on the lower side of the substrate where the thin film transistor Tr is disposed. In addition, when the organic light emitting display device is a top emission type, visible light generated from the organic light emitting layer 110 is displayed on an upper side of the substrate on which the thin film transistor Tr is disposed.

In addition, although not shown in the drawing, a sealing layer for protecting the organic electroluminescent device may further be disposed on a front surface of the substrate 100 on which the second electrode 115 is disposed. Then, another substrate disposed opposite to the substrate 100 is bonded to the substrate 100 using a bonding agent. Here, the bonding agent may be a photo-curing resin or a thermosetting resin, and the spacing space between the bonded substrates may be filled with air, nitrogen or a bonding agent.

The organic electroluminescent device of the organic light emitting display according to the present invention includes a first conductive layer 121 made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) And a third conductive layer 122 disposed on the second conductive layer 122 and made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x ) And the first electrode 120 composed of the first electrode 120 and the second electrode 123, thereby improving the transmittance and color purity and simplifying the structure.

Next, with reference to FIG. 4, the transmittance of the first electrode of the organic electroluminescent device according to the comparative example and the first electrode of the organic electroluminescent device according to the present invention will be described. 4 is a graph showing the transmittance of the first electrode of the organic electroluminescent device according to the comparative example and the example.

The first electrode of the organic light emitting display device according to the comparative example includes a first conductive layer, a second conductive layer disposed on the first conductive layer, and a third conductive layer disposed on the second conductive layer. Here, the first conductive layer and the third conductive layer are made of indium tin oxide (ITO), and the second conductive layer is made of silver (Ag).

A first electrode of an organic light emitting display according to an embodiment includes a first conductive layer, a second conductive layer disposed on the first conductive layer, and a third conductive layer disposed on the second conductive layer. Here, the first conductive layer and the third conductive layer are made of tungsten oxide (WO _x ), and the second conductive layer is made of silver (Ag).

Referring to FIG. 4, the transmittance (B) of the first electrode and the transmittance (C) of the first electrode according to the embodiment are compared with the transmittance (C) of the first electrode according to the embodiment It can be seen that the transmittance (B) of the first electrode according to the comparative example is significantly higher than that of the first electrode in the visible light wavelength range.

In detail, it can be seen that the transmittance (C) of the first electrode according to the embodiment has a transmittance of about 90% or more at a visible light wavelength band. In addition, it can be seen that the transmittance (B) of the first electrode according to the comparative example has a transmittance of about 45% to 70% at a visible light wavelength band. Therefore, it can be seen that the transmittance (C) of the first electrode according to the embodiment is significantly higher than the transmittance (B) according to the comparative example in the visible light wavelength range.

It can also be seen that the transmittance (C) of the first electrode according to the embodiment is substantially similar to the transmittance (A) of indium tin oxide (ITO), which is a transparent conductive material, in the visible light wavelength range.

That is, the first electrode according to the present invention includes a first conductive layer made of tungsten oxide (WO _x ), a second conductive layer disposed on the first conductive layer and made of silver (Ag) And a third conductive layer made of tungsten oxide (WO _x ), thereby achieving a high transmittance at a visible light wavelength band.

The features, structures, effects and the like described in the foregoing embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. Further, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. It can be seen that various modifications and applications are possible. For example, each component specifically shown in the embodiments may be modified and implemented. It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.

100: substrate
120: first electrode
121: first conductive layer
122: second conductive layer
123: Third conductive layer
110: organic light emitting layer
111: hole transport layer

Claims (12)

A second conductive layer disposed on the first conductive layer and made of a different material from the first conductive layer, and a second conductive layer disposed on the second conductive layer and made of a different material from the second conductive layer, A first electrode composed of a third conductive layer;
An organic light emitting layer on the first electrode; And
And a second electrode on the organic light emitting layer.
The method according to claim 1,
Wherein the first conductive layer and the third conductive layer are made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x )
And the second conductive layer is made of silver (Ag).
The method according to claim 1,
Wherein the organic light emitting layer includes a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer.
The method according to claim 1,
Wherein a work function of the first electrode is 6 eV to 6.3 eV.
The method according to claim 1,
Wherein a difference between a HOMO energy level of the first electrode and a hole transport layer of the organic light emitting layer is 0.7 eV or less.
The method according to claim 1,
The thickness of the first conductive layer and the third conductive layer is 35 nm to 60 nm,
Wherein the thickness of the second conductive layer is 10 nm to 15 nm.
Board;
A thin film transistor on the substrate;
An organic electroluminescent device electrically connected to the thin film transistor and including a first electrode, an organic light emitting layer on the first electrode, and a second electrode on the organic light emitting layer; And
And an encapsulation layer disposed on the organic electroluminescence device,
Wherein the first electrode of the organic electroluminescent device includes a first conductive layer and a second conductive layer disposed on the first conductive layer and made of a different material from the first conductive layer, And a third conductive layer made of a different material from the second conductive layer.
8. The method of claim 7,
Wherein the first conductive layer and the third conductive layer are made of tungsten oxide (WO _x ) or molybdenum oxide (MoO _x )
And the second conductive layer is made of silver (Ag).
8. The method of claim 7,
Wherein the organic light emitting layer comprises a hole transporting layer, a light emitting layer, an electron transporting layer, and an electron injecting layer.
8. The method of claim 7,
And the work function of the first electrode is 6 eV to 6.3 eV.
8. The method of claim 7,
Wherein the HOMO energy level difference between the first electrode and the hole transport layer of the organic light emitting layer is 0.7 eV or less.
8. The method of claim 7,
The thickness of the first conductive layer and the third conductive layer is 35 nm to 60 nm,
And the thickness of the second conductive layer is 10 nm to 15 nm.

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