KR20070060973A - Light emitting device and fabrication method the same and organic light emitting device passivation film having multiple layers - Google Patents

Abstract

A light emitting device, a fabricating method thereof, and an organic light emitting device passivation of a multi-layered structure are provided to secure a low oxygen permeability and water vapor permeation by using a thin film made of organic and inorganic materials. First electrodes(12) are formed on a substrate, and a light emitting active layer(13) composed of at least one layer is formed on the first electrode. Second electrodes(14) are formed on the light emitting active layer. A multi-layered passivation(15) are formed on the second electrode to protect the first and second electrodes and the active layer. The passivation has a first buffer layer(15a) formed on the second electrode, a second buffer layer(15b) formed on the first buffer layer, and a protective layer(15c) formed on the second buffer layer.

Description

Light Emitting Device and Fabrication Method The same and Organic Light Emitting Device Passivation film having Multiple layers

1A to 1C are cross-sectional views illustrating embodiments of a light emitting device according to the present invention.

2 is a graph showing current density-voltage-brightness characteristics of a light emitting device and another type of light emitting device according to an exemplary embodiment of the present invention.

3 is a graph showing efficiency characteristics of a light emitting device different from that of a light emitting device according to an exemplary embodiment of the present invention.

4 is a light emission spectrum of a light emitting device different from the light emitting device according to the exemplary embodiment of the present invention.

5A is a photograph of a light emitting image of a light emitting device according to an embodiment of the present invention, and FIGS. 5B and 5C are photographs of a light emitting image of a comparative embodiment for comparison with FIG. 5A.

<Description of the symbols for the main parts of the drawings>

10: light emitting element 11: substrate

12: first electrode 13: light emitting active layer

13a: hole transport layer 13b: light emitting layer

13c: electron transport layer 14: second electrode

15: protective film 15a: first buffer layer

15b: second buffer layer 15c: protective layer

The present invention relates to a multi-layered light emitting device protective film, a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device comprising a protective film made of a multi-layer to prevent the inflow of moisture and oxygen, A light emitting element protective film.

Generally, a light emitting device does not require an external light source and emits light by itself. In particular, the light emitting device has a high luminous efficiency, an excellent brightness and viewing angle, and a fast response speed. Inflow into the inside of the electrode is oxidized or deterioration of the device itself has a disadvantage that the life is shortened.

Accordingly, various researches for producing light emitting devices stable to moisture and oxygen have been conducted. These various studies include a method of manufacturing a protective layer made of organic or inorganic materials using a vacuum deposition method, a method of forming a protective layer by forming a polymer on an electrode of a light emitting device by using a spin coating method or a molding method, oxygen or moisture A method of fabricating a protective layer for encapsulating a light emitting device by encapsulating a polymer thin film having a low transmittance, and a method of covering a device with a shield glass and then filling a silicon oil between the device and the shield glass have been proposed.

Among the most widely known methods, a protective film is manufactured by a dry process using a vacuum deposition apparatus. A method of depositing a polymer or thin film by depositing a liquid or solid monomer and then polymerizing a polymer thin film onto a light emitting device and an inorganic thin film by depositing an inorganic material A method of forming and depositing a film, a method of laminating an organic material and an inorganic material together, and the like are known. In particular, US Pat. No. 6,268,695 proposes a protective layer composed of an organic / inorganic composite layer formed by vacuum deposition by J. D. Affinito of the Batelle Memorial Institute. As described above, the conventionally proposed protective film is generally composed of an organic thin film capable of removing the stress of the inorganic thin film and a mixed layer of an inorganic thin film having excellent moisture permeability and oxygen permeability.

However, an inorganic thin film constituting the protective layer having such a structure is generally deposited by a thin film manufacturing method using plasma. When manufacturing an inorganic thin film using plasma, the components of the light emitting device formed under the protective layer affect the plasma. Thereby, there is a problem that can reduce the characteristics of the light emitting device itself.

Therefore, the present invention is an invention devised to solve the above problems, and an object of the present invention is to provide a light emitting device protective film and a light emitting device having a multi-layer structure that can more securely protect the components of the light emitting device and a method of manufacturing the same. . An object of the present invention is to form a protective film of a multi-layer structure on the second electrode constituting the light emitting device, a light emitting device protective film and a light emitting device having a multi-layer structure that can block the flow of oxygen, moisture, etc. into the light emitting device and its manufacture To provide a way.

According to an aspect of the present invention for achieving the above object, the present light emitting device comprises: a first electrode formed on a substrate; A light emitting active layer comprising at least one layer formed on the first electrode; A second electrode formed on the light emitting active layer; A protective film having a multilayer structure formed on the second electrode to protect the first and second electrodes and the active layer.

Preferably, the passivation layer is formed on the second electrode and the first buffer layer made of an organic material, the second buffer layer formed on the first buffer layer and made of an inorganic material, and formed on the second buffer layer and an inorganic material. It includes a protective layer consisting of. Here, the first buffer layer includes at least one of NPB and Alq3, the second buffer layer comprises at least one of LiF, CaF, CsF, the first buffer layer and the second buffer layer is deposited by thermal evaporation. The inorganic material forming the protective layer includes indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), and zinc oxide (ZnO) in which Al or Ga is added. The multilayer protective film may be formed by repeatedly depositing the first buffer layer, the second buffer layer, and the protective layer a plurality of times.

The light emitting active layer includes a hole transport layer formed on the first electrode, a light emitting layer formed on the hole transport layer, and an electron transport layer formed on the light emitting layer, and the light emitting active layer includes the first electrode and the hole transport layer. It further includes a hole injection layer formed between, and an electron injection layer formed between the electron transport layer and the second electrode.

According to another aspect of the invention, the method of manufacturing the light emitting device comprises the steps of forming a first electrode on the substrate; Forming a light emitting active layer including a light emitting layer on the first electrode; Forming a second electrode on the light emitting active layer; And forming a protective film having a multilayer structure formed on the second electrode to protect the first electrode, the light emitting active layer, and the second electrode.

The forming of the passivation layer may include forming a first buffer layer made of an organic material on the second electrode; Forming a second buffer layer made of an inorganic material on the first buffer layer; And forming a protective layer made of an inorganic material on the second buffer layer. Forming the first buffer layer and the second buffer layer is formed using a vacuum thermal evaporation method. Forming the protective layer is formed by using a plasma deposition method. Forming the light emitting active layer includes forming a hole injection layer and a hole transport layer between the first electrode and the light emitting layer, and forming an electron transport layer and an electron injection layer between the light emitting layer and the second electrode. . After forming the protective film of the multi-layer structure, further comprising forming an encapsulation layer on the protective film.

On the other hand, according to another aspect of the invention, the organic light emitting element protective film of the present multilayer structure is a first electrode formed on a substrate, a light emitting active layer formed on the first electrode, a second electrode formed on the light emitting active layer Is deposited on top of the organic light emitting device comprising a protecting the first electrode, the light emitting active layer and the second electrode, the organic buffer first layer, the inorganic buffer second layer formed on the first buffer layer, It includes an inorganic protective layer formed on the second buffer layer. The first buffer layer and the second buffer layer are formed using a thermal evaporation method. The protective layer is formed using a plasma deposition method.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, embodiments of the light emitting device according to the present invention will be described in detail with reference to the accompanying drawings.

1A to 1C are cross-sectional views illustrating embodiments of a light emitting device according to the present invention.

1A to 1C, the light emitting device 10 includes a substrate 11, a first electrode 12 formed on the substrate 11, and a light emitting active layer formed on the first electrode 12 ( 13), a second electrode 14 formed on the light emitting active layer 13, and a protective film 15 having a multilayer structure formed on the second electrode 14.

Referring to the embodiment of FIG. 1A, the light emitting active layer 13 includes a hole transport layer 13a, a light emitting layer 13b, and an electron transport layer 13c, and the protective layer 15 having a multilayer structure includes a first buffer layer 15a. And a second buffer layer 15b and a protective layer 15c.

The substrate 11 uses glass, stainless steel, plastic, and the like, and selects and uses materials of the substrate according to top emission and back emission or double emission, and uses a lot of transparent materials. The first electrode 12 may be formed at least under the emission area to be formed on the substrate 11, and the first electrode 12 may also be formed differently according to front and rear emission or double emission. For example, in the case of back emission, the first electrode 12 uses a material having transparency such as ITO, IZO, ITZO, ZnO doped with Al or Ga, and in the case of top emission, ITO, IZO As well as ZnO doped with, ITZO, Al, or Ga, a metal electrode having a high work function (eg, Cr, Ni, Ag, Au) may be used.

The light emitting active layer 13 is formed on the first electrode 12. The light emitting active layer 13 includes a hole transport layer 13a, a light emitting layer 13b, and an electron injection layer 13c formed on the first electrode 12. In general, the light emitting active layer 13 is formed using an organic material such as NPB and Alq 3. The second electrode 14 is formed on the light emitting active layer 13. Like the first electrode 12, the second electrode 14 may be formed in various ways according to the light emission type (bilateral light emission, front light emission, rear light emission), and may be formed in a single layer or in multiple layers. .

Next, a protective film 15 having a multilayer structure is formed on the second electrode 14. The passivation layer 15 includes a first buffer layer 15a, a second buffer layer 15b, and a protective layer 15c. The first buffer layer 15a uses an organic material such as NPB, and the second buffer layer 15b. Uses inorganic materials such as LiF, CaF, CsF and the like. The first buffer layer 15a and the second buffer layer 15b formed on the second electrode 14 are deposited by thermal vacuum deposition, thereby protecting the light emitting active layer 13 formed under the second electrode 14. The second buffer layer 15b, which is an inorganic thin film, effectively prevents plasma damage that may occur during deposition, and serves to absorb moisture and oxygen from an organic material. In addition, the inorganic second buffer layer 15b has a high transmittance and is easy to apply to the front light emitting device, and also serves to maintain thermal and mechanical stability between the light emitting active layer 13 and the protective layer 15c. Can be.

 The protective layer 15c formed on the first buffer layer 15a and the second buffer layer 15b is made of an inorganic material in a thin film form. Typically, the protective layer 15c may be formed by various deposition methods, including a sputtering method, a chemical vapor deposition method, an ALD method, and the like. The protective layer 15c may be formed by selecting from indium tin oxide (ITO), indium zinc oxide (IZO), silicon oxide (SiO 2), silicon nitride (Si 3 N 4), zinc oxide (ZnO), AlO, or the like. An encapsulation layer formed by another encapsulation method such as a glass shield may be formed on the protective film 15 of the above-described multilayer structure (including the first and second complete layers and the protective layer).

Referring to the embodiment of FIG. 1B, since all components except for the second electrode 14 are the same as those of FIG. 1A, detailed descriptions of other components are replaced with the description of FIG. 1A. The second electrode 14 disclosed in FIG. 1B has a multilayer structure including a lower electrode layer 14a and an upper electrode layer 14b. In the present embodiment, the second electrode 14 has Al, Mg, Ca having excellent conductivity. Electrode stability can be attained by including the lower electrode layer 14a deposited using etc. and the upper electrode layer 14b which is low in oxidization like Ag formed on the electrode layer 14a.

Referring to the embodiment of FIG. 1C, since all components except for the light emitting active layer 14 and the second electrode 14 are the same as those of FIG. 1A, a detailed description of the other components will be described with reference to FIG. 1A. Replace with The light emitting active layer 13 disclosed in FIG. 1C includes a hole injection layer 13d, a hole transport layer 13a, a light emitting layer 13b, an electron transport layer 13c, and an electron injection layer 13e, and a second electrode 14. Includes a lower electrode layer 14a and an upper electrode layer 14b. The hole injection layer 13d, the hole transport layer 13a, the light emitting layer 13b, the electron transport layer 13c, and the electron injection layer 13e constituting the light emitting active layer generally use organic materials such as NPB and Alq3. Is formed. The second electrode 14 includes a lower electrode layer 14a deposited using Al, Mg, Ca, and the like having excellent conductivity, and an upper electrode layer 14b having a low oxidizing property such as Ag formed on the electrode layer 14a. The stability of the electrode can be achieved. Although disclosed in the above embodiments, the encapsulation layer may be further formed on the passivation layer 15 using various methods (encapsulation method). In the above-described embodiment, it is disclosed that all the layers constituting the light emitting active layer 13 are formed of an organic material. However, all of the layers constituting the light emitting active layer 13 may be made of an inorganic material. It may consist of organic material and some other layers may consist of inorganic material.

2 is a graph for experimenting the current density-voltage-brightness characteristics of the light emitting device according to an embodiment of the present invention. In order to test the current density-voltage-brightness characteristics of the light emitting device according to the present invention, in one embodiment of the light emitting device, the substrate 11 / first electrode 12 / active layer 13 / second electrode 14 / A light emitting element composed of a multi-layered protective film 15 is used.

In order to reliably reveal the current density-voltage-brightness characteristics of the light emitting device according to the present invention, an experiment was performed by manufacturing light emitting devices comparable to the light emitting device according to the present invention. The light emitting device 10 according to the present invention is a glass substrate 11 / first electrode 12 / hole transport layer 13a / light emitting layer 13b / electron transport layer 13c / lower electrode layer 14a / upper electrode layer 14b ) / First buffer layer 15a / second buffer layer 15b / protective layer 15c.

Specifically, the light emitting device 10 includes Glass (11) / ITO (12) / NPB (60nm: 13a) / Alq3 (60nm: 13b) / LiF (1nm: 13c) / Al (2nm: 14a) / Ag ( 20 nm: 14b) / NPB (50 nm: 15a) / LiF (10 nm: 15b) / IZO (50 nm: 15c). Comparative embodiments for comparing the characteristics with the present light emitting device 10 are made as follows. The light emitting device 100 of the comparative example is made of Glass / ITO / NPB (60nm) / Alq3 (60nm) / LiF (1nm) / Al (2nm) / Ag (20nm) / LiF (10nm) / IZO (50nm). In another comparative embodiment, the light emitting device 200 is made of Glass / ITO / NPB (60nm) / Alq3 (60nm) / LiF (1nm) / Al (2nm) / Ag (20nm) / NPB (50nm) / IZO (50nm). Is done.

Hereinafter, for convenience of description, the structure of the light emitting device is summarized in a table.

Number of light emitting elements  Structure of Light-Emitting Element According to Embodiment 10 Glass / ITO / NPB / Alq3 / LiF / Al / Ag / NPB / LiF / IZO 100 Glass / ITO / NPB / Alq3 / LiF / Al / Ag / LiF / IZO 200 Glass / ITO / NPB / Alq3 / LiF / Al / Ag / NPB / IZO

In the graph of FIG. 2, the horizontal axis represents voltage, the vertical axis on the left represents current density, and the vertical axis on the right represents brightness. First, looking at the voltage, the current density and the voltage graph, it can be seen that the voltage-current density graph of the light emitting device 10 is more stable than the graphs of the light emitting device 100 and the light emitting device 200. In addition, looking at the voltage and brightness graph, it can be seen that the brightness of the light emitting device 10 is 1.5 to 2 times higher than the light emitting device 100 and the light emitting device 200.

3 is a graph showing efficiency characteristics of a light emitting device different from that of a light emitting device according to an exemplary embodiment of the present invention. 3, the horizontal axis represents voltage, and the vertical axis represents external quantum efficiency (Ext.Q.E.). Referring to the graphs of FIG. 3, it can be seen that the efficiency of the light emitting device 10 is improved compared to the light emitting device 100 and the light emitting device 200.

4 is a light emission spectrum of a light emitting device different from the light emitting device according to the exemplary embodiment of the present invention. 4, the horizontal axis represents wavelength, and the vertical axis represents normalized EL intensity. Referring to FIG. 4, it can be seen that the graphs 10, 100, and 200 of all three light emitting devices emit light in the green region, whereby the layer of the protective film does not affect the existing protective film. This can be seen from the emission spectrum results.

5A is a photograph of a light emitting image of a light emitting device according to an embodiment of the present invention, and FIGS. 5B and 5C are photographs of a light emitting image of a comparative embodiment for comparison with FIG. 5A. 5A through 5C, since dark spots are not observed in the light emitting device 10 than in the light emitting device 100 and the light emitting device 200, damage by plasma is effectively prevented. It can be seen that.

Referring to FIGS. 2 to 5 (a to c), according to the light emission characteristics of the light emitting device according to the present invention, the first buffer layer 15a made of an organic material, the second buffer layer 15b made of an inorganic material, and a protective layer In the case of the light emitting device 10 including the 15c, it can be seen that the light emitting devices 100 and 200 that do not include all of them exhibit significantly improved characteristics in brightness, efficiency and degree of plasma damage.

Although the present invention has been described with reference to the embodiments illustrated in the accompanying drawings, it is merely an example, and those skilled in the art may understand that various modifications and equivalent other embodiments are possible. There will be.

As described above, according to the present invention, by using a protective film having a multi-layer structure, it is easy to secure a low oxygen permeability and a moisture permeability, and in the present invention, a second buffer layer is introduced to prevent the deterioration of characteristics of the light emitting device by plasma. As a result, it is possible to prevent a decrease in the light emission characteristics of the light emitting device.

In addition, the present invention provides a buffer layer consisting of two layers, by using an organic film as a first buffer layer, the stress can be removed, by depositing an inorganic film as a second buffer layer, to reduce the damage that can occur in the plasma process Not only that, but also the effect of removing moisture. Accordingly, it is possible to more stably protect the components of the light emitting device from the plasma process, it is possible to improve the life of the light emitting device.

Claims (18)

A first electrode formed on the substrate; A light emitting active layer comprising at least one layer formed on the first electrode; A second electrode formed on the light emitting active layer; A protective film having a multilayer structure formed on the second electrode to protect the first and second electrodes and the active layer. Light emitting device comprising a. The method of claim 1, wherein the protective film A first buffer layer formed on the second electrode and made of an organic material; A second buffer layer formed on the first buffer layer and made of an inorganic material; A protective layer formed on the second buffer layer and made of an inorganic material Light emitting device comprising a. The method of claim 2, The first buffer layer includes at least one of NPB and Alq3. The method of claim 2, The second buffer layer includes at least one of LiF, CaF, and CsF. The method according to claim 3 or 4, The first buffer layer and the second buffer layer is a light emitting device is deposited by the thermal evaporation method. The method of claim 2, The inorganic material constituting the protective layer is a light emitting device including indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide (ZnO) to which Al or Ga is added. The method of claim 2, The multi-layered protective film may be formed by repeatedly depositing the first buffer layer, the second buffer layer, and the protective layer a plurality of times. The method of claim 1, The light emitting active layer is a hole transport layer formed on the first electrode, A light emitting device comprising a light emitting layer formed on the hole transport layer and an electron transport layer formed on the light emitting layer. The method of claim 8, The light emitting active layer A hole injection layer formed between the first electrode and the hole transport layer; The light emitting device further comprises an electron injection layer formed between the electron transport layer and the second electrode. Forming a first electrode on the substrate; Forming a light emitting active layer including a light emitting layer on the first electrode; Forming a second electrode on the light emitting active layer; And Forming a protective film having a multilayer structure formed on the second electrode to protect the first electrode, the light emitting active layer, and the second electrode; Method of manufacturing a light emitting device comprising a. The method of claim 10, Forming the protective film Forming a first buffer layer made of an organic material on the second electrode; Forming a second buffer layer made of an inorganic material on the first buffer layer; And Forming a protective layer made of an inorganic material on the second buffer layer Method of manufacturing a light emitting device further comprising. The method of claim 11, Forming the first buffer layer and the second buffer layer is a method of manufacturing a light emitting device formed by using a vacuum thermal evaporation method. The method of claim 12, Forming the protective layer is a method of manufacturing a light emitting device to be formed using a plasma deposition method. The method of claim 10, Forming the light emitting active layer Forming a hole injection layer and a hole transport layer between the first electrode and the light emitting layer; And forming an electron transport layer and an electron injection layer between the light emitting layer and the second electrode. The method of claim 10, After forming the protective film of the multi-layer structure, the method of manufacturing a light emitting device further comprising the step of forming an encapsulation layer on the protective film. A first electrode formed on the substrate, a light emitting active layer formed on the first electrode, and a second electrode formed on the light emitting active layer, and deposited on an organic light emitting device including the first electrode, the light emitting active layer and An organic light-emitting layer having a multi-layer structure that protects the second electrode and includes an organic first buffer layer, an inorganic second buffer layer formed on the first buffer layer, and an inorganic protective layer formed on the second buffer layer Device protection film. The method of claim 16, The first buffer layer and the second buffer layer of the organic light emitting device protective film of a multi-layer structure is formed using a thermal evaporation method. The method of claim 16, The protective layer is a multilayer organic light emitting device protective film formed by using a plasma deposition method.

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