KR101331973B1 - Organic light emitting device and display apparatus comprising the organic light emitting device - Google Patents

Abstract

According to an aspect of the invention, the substrate; A first electrode on the substrate; An organic light emitting layer on the first electrode; A thin film forming active layer on the organic light emitting layer; And a metal thin film positioned directly on the thin film forming active layer and serving as a second electrode.

Description

Organic light emitting device and display apparatus comprising the organic light emitting device

The present invention relates to an organic light emitting device, and a display device including the organic light emitting device.

The present invention is derived from a study conducted as part of the Knowledge Economy Technology Innovation Project (Industrial Source Technology Development Project) of the Ministry of Knowledge Economy and Korea Advanced Institute of Science and Technology Cooperation. [Task Management Number: 10035573, Title: Selective Transparent Display Research through Display Structure Innovation]

In the organic light emitting device, an organic light emitting layer is disposed between two opposite electrodes, and electrons injected from one electrode and holes injected from the other electrode are combined in the organic light emitting layer, and the light emitting molecules of the organic light emitting layer are excited by the bonding. It is a light emitting device that emits energy emitted by light while returning to the ground state.

A hole transport layer, an electron transport layer, etc. made of an organic material may be further provided between the organic light emitting layer and the electrode. Since the organic material is transparent in the visible light region, if both electrodes of the organic material can be made transparent, a transparent organic light emitting device can be realized.

As the transparent electrode of the organic light emitting device, a transparent conductive oxide (TCO) including indium tin oxide (ITO) or the like is widely used. The transparent conductive oxide is mainly deposited by RF sputtering, which is difficult to use as an upper electrode of the organic light emitting device because it may damage the organic material including the organic light emitting layer. In addition, due to the characteristics of the organic material that is weak to heat, sufficient thermal conductivity and electrical conductivity for using the transparent conductive oxide as the upper electrode of the organic light emitting device are not sufficient because the thermal conduction (annealing) cannot be performed after the transparent conductive oxide is deposited on the organic material. Hard to get.

On the other hand, when a metal thin film is formed by thermal evaporation of a metal such as silver (Ag) or gold (Au) having a low optical absorption rate, it has excellent electrical conductivity characteristics of the metal itself and produces a semitransparent metal thin film. You can get it. However, in the case of using the metal thin film as described above, although the electrical conductivity of the metal itself is excellent, it is not easy to obtain improved transmittance because there is much absorption or reflection in the metal itself.

The present invention provides an organic light emitting device including a transparent metal thin film having improved transmittance and electrical conductivity as an upper electrode and a wiring, and an organic light emitting display device including the organic light emitting device in order to solve the above and other problems. I would like to.

According to an aspect of the invention, the substrate; A first electrode on the substrate; An organic light emitting layer on the first electrode; A thin film forming active layer on the organic light emitting layer; And a metal thin film positioned directly on the thin film forming active layer and serving as a second electrode.

According to another feature of the invention, the thin film forming active layer can improve the transmittance and electrical conductivity of the metal thin film.

According to another feature of the invention, the thin film-forming active layer may comprise a carbonate.

According to another feature of the invention, the thin film forming active layer may include cesium carbonate (Cs 2 CO 3).

According to another feature of the invention, the metal thin film may include at least one metal selected from silver (Ag), gold (Au) and copper (Cu).

According to another feature of the invention, the thickness of the metal thin film may be 3nm or more and 30nm or less.

According to another feature of the invention, the metal thin film may be a cathode (cathode).

According to another feature of the invention, the substrate and the first electrode may be a transparent substrate and a transparent electrode, respectively.

According to another feature of the invention, the optical capping layer may be further provided on the metal thin film.

According to another feature of the invention, the optical capping layer may comprise zinc sulfide (ZnS).

According to another feature of the present invention, a wiring region is further provided on the substrate, and the wiring region includes a layer (second thin film forming active layer) including the same material as the thin film forming active layer and the same material as the metal thin film. A layer (second metal thin film) can be used as the wiring.

According to another feature of the present invention, a planarization layer may be further provided between the substrate in the wiring region and the second thin film forming active layer.

According to another feature of the invention, the planarization layer may comprise zinc sulfide (ZnS).

According to another feature of the invention, the optical capping layer may be further provided on the second metal thin film of the wiring area.

According to another feature of the invention, the optical capping layer may comprise zinc sulfide (ZnS).

According to another aspect of the present invention, an organic light emitting display device including the organic light emitting device described above can be provided.

According to another feature of the invention, the organic light emitting display device further comprises a wiring region on the substrate, the layer (second thin film forming active layer) and the metal thin film including the same material as the thin film forming active layer in the wiring region. A layer (second metal thin film) containing the same material as that may be used as the wiring.

According to the organic light emitting device and the organic light emitting display device according to an aspect of the present invention described above, it provides the following effects.

First, the thin film forming active layer may improve the transmittance and electrical conductivity of the metal thin film.

Second, the metal thin film having the thin film forming active layer may be used as an upper electrode of the transparent organic light emitting device and the organic light emitting display without damaging the organic material.

Third, the metal thin film provided with the thin film forming active layer may be used as a transparent wiring of the transparent organic light emitting device and the organic light emitting display device.

1 is a schematic cross-sectional view of an organic light emitting diode 1 according to a first exemplary embodiment of the present invention.
2 is a graph showing the relationship between the presence or absence of a thin film forming active layer and the thickness of the metal thin film on the transmittance of the metal thin film.
Figure 3 shows a scanning electron microscopy (SEM) image of the metal thin film with or without the thin film forming active layer.
4 is a view showing optical constants (n, k) of a metal thin film with or without a thin film forming active layer.
5 is a graph illustrating a current density (J) -voltage (V) relationship of a transparent organic light emitting diode with or without a thin film forming active layer.
6 is a schematic cross-sectional view of an organic light emitting diode 2 according to a second exemplary embodiment of the present invention.
7 is a graph showing transmittance according to the presence or absence of a thin film-forming active layer of an organic light emitting device having a metal thin film and an optical capping layer.
8 is a schematic cross-sectional view of an organic light emitting diode 3 according to a third exemplary embodiment of the present invention.
9 is a graph showing the transmittance of wirings with or without a second thin film-forming active layer between the planarization layer and the second metal thin film.
10 is a schematic cross-sectional view of an organic light emitting diode 4 according to a fourth embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic cross-sectional view of an organic light emitting diode 1 according to a first exemplary embodiment of the present invention. Referring to FIG. 1, the organic light emitting diode 1 according to the present exemplary embodiment may include a substrate 110, a first electrode 120, an organic emission layer 130, a thin film formation active layer 140, and a metal thin film as a second electrode. 150).

The substrate 110 may be provided not only as a glass substrate but also as a transparent substrate such as a plastic substrate including polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide, and the like.

The first electrode 120 of the organic light emitting device 1 is provided on the substrate 110. The first electrode 120 may be provided as a transparent electrode. Transparent electrodes are transparent conductive oxides (TCO) such as indium tin oxide (ITO), fluorine doped tin oxide (FTO), PEDOT: conducting polymers (PSS), carbon nanotubes (CNT), graphene oxide (Graphene oxid), And various forms such as a metal thin film may be made of a single layer or multiple layers.

The organic emission layer 130 is provided between the first electrode 120 and the metal thin film 150 that is the second electrode. Various materials may be formed between the organic emission layer 130 and the first electrode 120 and / or between the organic emission layer 130 and the metal thin film 150 as the second electrode. In addition, an inorganic material may be further included between the organic emission layer 130 and the first electrode 120 and / or between the organic emission layer 130 and the metal thin film 150 that is the second electrode. The organic light emitting layer 130 may be formed of a low molecular or high molecular organic material.

The thin film formation active layer 140 is provided on the organic emission layer 130. The thin film formation active layer 140 improves the transmittance and electrical conductivity of the metal thin film 150 as the second electrode. The thin film formation active layer 140 may include carbonate and cesium carbonate (Ca 2 CO 3).

The metal thin film 150, which is the second electrode of the organic light emitting diode 1, is directly disposed on the thin film formation active layer 140. The metal thin film 150 may include one or more selected from silver (Ag), gold (Au), and copper (Cu). These metals are metals with excellent electrical conductivity. However, since these metals have a property of reflecting themselves, a thicker thickness increases electrical conductivity but lowers transmittance. Therefore, in order for the metal thin film 150 to be used as the transparent electrode of the organic light emitting device 1, the thickness thereof should not be thick. It is preferable that the thickness of the metal thin film suitable for use as a transparent electrode is 3 nm or more and 30 nm or less.

FIG. 2 is a graph showing a relationship between the presence or absence of the thin film formation active layer 140 and the thickness of the metal thin film 150 on the transmittance of the metal thin film 150.

In detail, FIG. 2 uses a glass substrate as the substrate 110, ITO having a thickness of 150 nm as the first electrode 120, NPB having a thickness of 50 nm as the hole transport layer, and an organic light emitting layer 130. Alq3 having a thickness of 50 nm is used, and silver (Ag) having a thickness of 9 nm, 12 nm, and 15 nm is used as the metal thin film 150, respectively, and the thin film is formed between the organic light emitting layer 130 and the metal thin film 150. Transmittance according to wavelength when the forming active layer 140 is provided (w / Cs2CO3) and when the thin film forming active layer 140 is not provided (w / o Cs2CO3) and the thickness of the metal thin film 150. Is the result of measurement. Here, Seshu carbonate (Cs 2 CO 3) was used as the thin film formation active layer 140.

Referring to FIG. 2, even in the case of silver (Ag) thin films having the same thickness, there is a thin film forming active layer 140 ((w / Cs 2 CO 3) is more than a thin film forming active layer 140 (w / o Cs 2 CO 3). It can be seen that the high transmittance is shown.

In the absence of the thin film forming active layer 140, the transmittance at the thickness of the silver (Ag) thin film is almost the same at 9 nm and 12 nm, and the transmittance gradually decreases to 15 nm. On the other hand, in the case where the thin film forming active layer 140 has a thickness of 9 nm, the transmittance is best, and as the thickness increases, the transmittance decreases. That is, when the thin film forming active layer 140 is present, it can be seen that the correlation between the thickness and the transmittance of the metal thin film 150 is greater than when the thin film forming active layer 140 is not present. Therefore, when the thin film forming active layer 140 is present, it can be seen that the thin metal film 150 having a thinner thickness that satisfies the transmittance property is well made.

Table 1 shows the case where the thin film forming active layer 140 and the thin film forming active layer 140 are not provided between the organic light emitting layer 130 and the metal thin film 150 of FIG. 2, and the metal thin film 150. It shows the results of measuring sheet resistance against the thickness of.

Referring to Table 1, it can be seen that, at the same thickness, the case where the thin film forming active layer is present is smaller than the case where the thin film forming active layer is absent. In addition, even though the thickness of the thin film is different, it can be seen that a thin sheet resistance can be obtained even at a thinner thickness than when the thin film forming active layer is present. For example, if the thin film forming active layer has a thickness of 12 nm, the sheet resistance is 5.6 Ω / □. In the absence of the thin film forming active layer, the sheet resistance is 5.8 Ω / □ when the thickness of the silver thin film is 15 nm. A thin film having a smaller sheet resistance can be produced even with a thinner thickness when there is a forming active layer than without a thin film forming active layer.

Silver Thin Film Thickness (nm) Sheet resistance (Ω / □) If you have Cs2CO3 Without Cs2CO3 9 7.1 8.8 12 5.6 7.4 15 5.2 5.8

3 illustrates a scanning electron microscopy (SEM) image of the metal thin film 150 with or without the thin film formation active layer 140.

The left image of FIG. 3 is an SEM image of a 12 nm thick silver (Ag) thin film without cesium carbonate as a thin film forming active layer, and the right image shows a 12 nm thick silver (Ag) thin film with cesium carbonate as a thin film forming active layer. SEM image. Referring to the image, it can be seen that the presence of cesium carbonate shows less boundary between silver (Ag) particles than without cesium carbonate. That is, cesium carbonate increases the continuity and uniformity of the silver (Ag) thin film.

4 is a view showing optical constants (n, k) of the metal thin film 150 with or without the thin film formation active layer 140.

Referring to FIG. 4, among the optical constants (n, k) of the silver (Ag) thin film, the absorption coefficient (k) has no significant difference in the presence or absence of cesium carbonate (Cs-2CO3), but a refractive index. ) (n) shows a big difference depending on the presence or absence of cesium carbonate (Cs-2CO3). In general, when the scattering is large in the metal thin film 150, the refractive index n becomes large, and when the surface plasmon resonance is large, the absorption coefficient k becomes large. Therefore, referring to FIG. 4, when the silver (Ag) thin film is formed on cesium carbonate (Cs 2 CO 3), the cesium carbonate reduces scattering occurring at the boundary of the silver (Ag) thin film, thereby allowing the electrical conductivity and electrical conductivity of the silver (Ag) thin film to be reduced. It can be seen that the conductivity is improved.

According to the embodiment of the present invention described above, when the metal thin film 150 is formed directly on the thin film forming active layer 140, the thin film forming active layer 140 improves the transmittance and electrical conductivity of the metal thin film 150. Therefore, the metal thin film 150 may be used as a transparent upper electrode of the organic light emitting device that satisfies both the transmittance and the electrical conductivity. Furthermore, when the substrate 110 and the first electrode 120 are used as the transparent substrate and the transparent electrode, respectively, and the metal thin film 150 having excellent transmittance and electrical conductivity is applied as the upper electrode of the organic light emitting diode, A light emitting device can be implemented.

FIG. 5 is a graph illustrating a current density (J) -voltage (V) relationship of the transparent organic light emitting diode with or without the thin film formation active layer 140.

Referring to the figure, it can be seen that the current density (J) -voltage (V) curve of the transparent organic light emitting device with cesium carbonate having a thickness of 1.5 nm is shifted toward a voltage lower by about 4 V than without the cesium carbonate. Can be. That is, in the present exemplary embodiment, the thin film forming active layer 140 may perform a function of improving carrier injection characteristics of the organic light emitting diode 1. In particular, the transparent electrode 120 of the organic light emitting diode 1 may serve as an anode. It can be seen that when the metal thin film 150 functions as a cathode, cesium carbonate can improve electron injection characteristics of the metal thin film.

6 is a schematic cross-sectional view of an organic light emitting diode 2 according to a second exemplary embodiment of the present invention. The present embodiment will be described below centering on the difference from the first embodiment described above.

Referring to FIG. 6, the organic light emitting diode 2 according to the present exemplary embodiment may include a substrate 110, a first electrode 120, an organic emission layer 130, a thin film formation active layer 140, and a metal thin film as a second electrode. 150 and an optical capping layer 160 positioned on the metal thin film 150.

The optical capping layer 160 is further formed to reduce the reflection of the metal thin film 150, and may include zinc sulfide (ZnS).

FIG. 7 is a graph showing transmittance according to the presence or absence of the thin film forming active layer 140 of the organic light emitting diode 2 including the metal thin film 150 and the optical capping layer 160.

7, ITO is used as the first electrode 120 on the glass substrate 110, NPB having a thickness of 50 nm is used as the hole transporting layer, and Alq 3 having a thickness of 50 nm is used as the organic light emitting layer 130. Silver (Ag) having a thickness of 15 nm is used as the metal thin film 150, and zinc sulfide (ZnS) having a thickness of 37 nm is used as the optical capping layer 160, but the organic light emitting layer 130 and the metal thin film 150 are used. In the case where cesium carbonate is provided as the thin film forming active layer 140 (w / Cs 2 CO 3) and without (w / o Cs 2 CO 3), the transmittance T of the transparent organic light emitting diode is measured.

Referring to FIG. 7, even if the organic light emitting diode includes an optical capping layer 160 to reduce reflection of the metal thin film 140, the thin film forming active layer 140 is disposed between the organic light emitting layer 130 and the metal thin film 150. It can be seen that the provided case can improve the transmittance of the transparent organic light emitting device more than otherwise.

8 is a schematic cross-sectional view of an organic light emitting diode 3 according to a third exemplary embodiment of the present invention. The present embodiment will be described below centering on the difference from the first embodiment described above.

Referring to FIG. 8, the organic light emitting diode 3 according to the present exemplary embodiment includes a light emitting area E and a wiring area W. As shown in FIG.

The emission region E is the substrate 110, the first electrode 120, the organic emission layer 130, the thin film formation active layer 140, and the metal thin film, similar to the organic light emitting device 1 according to the first embodiment described above. And 150.

Meanwhile, the wiring area W is a region including various wirings electrically connected to the emission area E. The planarization layer 330 is provided on the substrate 110 and the emission area is formed on the planarization layer 330. A layer (second metal thin film forming active layer) 340 containing the same material as the thin film forming active layer 140 of (E) and a layer containing the same material as the metal thin film 150 of the emitting region (E) (second metal) Thin film) 350 is provided as a wiring. As described above, when the thin film forming active layer 140 is provided below the metal thin film 150, the permeability and the electrical conductivity of the metal thin film 150 are improved together, so that the second thin film forming active layer 340 and the second metal thin film are improved. 350 may be used as a transparent wiring of the organic light emitting device. Therefore, when the substrate 110 and the first electrode 120 are the transparent substrate and the transparent electrode, respectively, the light emitting region E and the wiring region W are both transparent, so that the transparent organic light emitting device can be implemented as a whole.

Meanwhile, zinc sulfide (ZnS) may be provided as the planarization layer 330 under the second thin film formation active layer 340. FIG. 9 is a graph showing the transmittance of wirings between the planarization layer 330 and the second metal thin film 350 with or without the second thin film formation active layer 340. The planarization layer 330 and the second metal thin film 350 It can be seen that the transmittance of the wiring including the second metal thin film 250 is improved more than when the second thin film formation active layer 340 is provided therebetween.

Meanwhile, although the thin film forming active layer 140, the second thin film forming active layer 340, and the metal thin film 150 and the second metal thin film 350 are located on different layers, the drawing of the present invention is performed. The exemplary embodiment is not limited thereto, and the thin film forming active layer 140, the second thin film forming active layer 340, and the metal thin film 150 and the second metal thin film 350 may be formed on the same layer. to be.

10 is a schematic cross-sectional view of an organic light emitting diode 4 according to a fourth embodiment of the present invention. Hereinafter, the present embodiment will be described focusing on differences from the first to third embodiments described above.

Referring to FIG. 10, the organic light emitting diode 4 according to the present exemplary embodiment includes a light emitting region E and a wiring region W, as in the third exemplary embodiment. However, the difference between the optical capping layers 160 and 360 is further provided on the metal thin film 150 and / or the wiring region W of the second metal thin film 350.

As in the above-described second embodiment, the optical capping layers 160 and 360 are further formed to reduce the reflection of the metal thin film 140 and the second metal thin film 340, and the optical capping layers 160 and 360 sulfide. Zinc (ZnS).

The embodiments and the drawings are only for the purpose of describing the contents of the invention in detail, and are not intended to limit the scope of the technical idea of the invention, the present invention described above is a general knowledge in the technical field to which the present invention belongs It is to be understood that various changes, modifications, and changes can be made without departing from the spirit and scope of the present invention, and are not limited to the embodiments and the accompanying drawings. It should be judged including the range of equality.

1 to 4: organic light emitting element 110: substrate
120: first electrode 130: organic light emitting layer
140: thin film formation active layer 150: metal thin film
] 60, 360: optical capping layer 330: planarization layer
340: second thin film forming active layer 350: second metal thin film
E: light emitting area W: wiring area

Claims (17)

Board;
A first electrode located on the substrate;
An organic light emitting layer disposed on the first electrode;
A thin film forming active layer on the organic light emitting layer; And
And a metal thin film positioned directly on the thin film forming active layer and being a second electrode.
A wiring region is further provided on the substrate,
An organic light emitting element in which a layer including the same material as the thin film forming active layer (second thin film forming active layer) and a layer containing the same material as the metal thin film (second metal thin film) are used as wiring in the wiring region. The method according to claim 1,
The thin film forming active layer improves the transmittance and electrical conductivity of the metal thin film. The method according to claim 1,
The thin film-forming active layer comprises an carbonate. The method of claim 3,
The thin film-forming active layer includes cesium carbonate (Cs 2 CO 3). The method according to claim 1,
The metal thin film includes at least one metal selected from silver (Ag), gold (Au), and copper (Cu). 6. The method of claim 5,
The thickness of the metal thin film is an organic light emitting device of 3nm or more and 30nm or less. The method according to claim 1,
The metal thin film is a cathode (cathode). The method according to claim 1,
And the substrate and the first electrode are transparent substrates and transparent electrodes, respectively. The method according to claim 1,
An organic light emitting device further comprising an optical capping layer on the metal thin film. 10. The method of claim 9,
And the optical capping layer includes zinc sulfide (ZnS). delete The method according to claim 1,
And a planarization layer between the substrate in the wiring region and the second thin film forming active layer. 13. The method of claim 12,
The planarization layer is an organic light emitting device comprising zinc sulfide (ZnS). The method according to claim 1,
And an optical capping layer on the second metal thin film in the wiring region. 15. The method of claim 14,
And the optical capping layer includes zinc sulfide (ZnS). An organic light emitting display device comprising the organic light emitting device of claim 1. delete

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