KR100440898B1 - Organic light-emitting devices - Google Patents

Abstract

The organic light emitting device includes a light emitting organic material layer positioned between a first electrode and a second electrode, wherein at least one of the first and second electrodes includes one or more electrode layers for injecting charge carriers into the light emitting organic material. And a layer of dielectric material over the surface of the outermost electrode layer away from the layer of luminescent organic material.

Description

Organic light emitting device {ORGANIC LIGHT-EMITTING DEVICES}

Organic light emitting devices as disclosed, for example, in US Pat. No. 5,247,190 or US Pat. No. 4,539,507 have great potential for use in various display applications. The contents of these patents are incorporated herein by reference. According to one method, an OLED is produced by coating a glass or plastic substrate with a transparent first electrode (anode), such as indium tin oxide (ITO). A thin film layer of at least one electroluminescent organic material is then deposited before the final layer. The final layer is a film of a second electrode (cathode), which is typically a metal or alloy.

In view of the electron injection properties, as the cathode material, a metal layer having a low work function such as calcium, or a metal alloy including a metal having a low work function is preferable. However, these low work function elements have inherent properties that readily react with reactive materials such as oxygen or moisture present in the environment. This reaction adversely affects the electron injection characteristics of the cathode, forming non-emitting black spots, which in turn degrades the performance of the device.

The present invention relates to organic light emitting devices (OLEDs).

Best Mode for Carrying Out the Invention Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

1 is a cross-sectional view of an organic light emitting device according to a first embodiment of the present invention.

2 is a cross-sectional view of an organic light emitting device according to a second embodiment of the present invention.

3 is a cross-sectional view of an organic light emitting device according to a third embodiment of the present invention.

4 is a cross-sectional view of an organic light emitting device according to a fourth embodiment of the present invention.

5 is a cross-sectional view of an organic light emitting device according to a fifth embodiment of the present invention.

6 is a cross-sectional view of an organic light emitting device according to a sixth embodiment of the present invention.

7 is a cross-sectional view of an organic light emitting device according to a seventh embodiment of the present invention.

It is an object of the present invention to provide an organic light emitting device which tends to form less non-emitting black spots, whereby performance degradation is significantly suppressed.

Another object of the present invention is to provide a method of manufacturing a protective cap for an electrode of an organic light emitting device which minimizes damage to the organic layers below.

According to one aspect of the invention, at least one light emitting organic material layer interposed between the first electrode and the second electrode, wherein at least one of the first and second electrodes is at least one electrode layer on the light emitting material And an stack having an inert barrier layer and at least one gettering layer interposed between the outermost electrode layer and the inert barrier layer to absorb moisture and oxygen. A light emitting device is provided.

The advantages of this aspect of the invention are particularly pronounced when the electrode on which the stack is formed comprises at least one layer deposited by vacuum evaporation.

The inert barrier layer serves to minimize the ingress of reactants into the device, and the gettering layer serves to absorb traces of reactant that have passed through the inert barrier layer.

The inert barrier layer is preferably an inorganic dielectric material layer selected from the group consisting of AlN, Al ₂ O ₃ , SiO ₂ , and Si ₃ N ₄ , preferably 0.01 to 10 μm, more preferably 1 to 10. Have a thickness in the μm range. The inert barrier layer is preferably deposited by sputtering techniques to provide a layer that does not include pinholes.

The gettering layer is preferably a layer of material that exhibits high reactivity to moisture and oxygen, such as for example an alloy such as Li, Ca, Ba or Cs, or LiAl, or a hygroscopic oxide such as BaO. to be. The gettering layer preferably has a thickness in the range of 0.01 to 5 μm. As the material of the gettering layer, calcium is particularly preferable. The gettering layer may be deposited by sputtering techniques to provide a layer that does not include pinholes. Alternatively, the gettering layer may be deposited by vacuum deposition.

According to another aspect of the present invention, there is provided a light emitting organic material layer inserted between a first electrode and a second electrode, wherein at least one of the first and second electrodes is for injecting charge carriers into the light emitting organic material layer. An organic light emitting device is provided that includes one or more electrode layers over the light emitting organic material layer, and further comprising a dielectric material layer over the surface of the outermost electrode layer away from the light emitting organic material layer.

The advantages of this aspect of the invention are also particularly pronounced when the dielectric layer or the electrode on which the dielectric layers are formed comprises at least one layer deposited by vacuum deposition.

According to an embodiment of the present invention, the organic light emitting device includes a second dielectric material layer on the first dielectric material layer, wherein the thicknesses of the first and second dielectric material layers are subjected to mechanical stress applied to the electrode. Selected to reduce.

Suitable dielectric materials for each of the first and second dielectric material layers include inorganic dielectric materials, preferably SiO, AlN, SiO ₂ , Si ₃ N ₄ and Al ₂ O ₃ . The thickness of each of the first and second dielectric material layers is preferably in the range of 0.01 to 10 μm, more preferably in the range of 1 to 10 μm.

The dielectric layers may be deposited by sputtering or vacuum deposition, respectively.

According to a third aspect of the invention, a protective cap over a first electrode of an organic light emitting device comprising at least one layer of light emitting organic material between first and second electrodes for injecting charge carriers into the organic light emitting material. A method is provided, the method comprising forming a first layer of dielectric material by vacuum deposition on a surface of a first electrode opposite the light emitting organic material layer.

The first electrode typically includes one or more metal layers, wherein a dielectric layer is directly formed on the surface of the outermost metal layer away from the organic light emitting material.

In addition, the barrier layers and / or gettering layers described above may be provided over the first dielectric layer.

Like the first and second aspects of the present invention, the advantages of the third aspect of the present invention stand out when the electrode of interest is deposited by vacuum deposition.

1 shows an organic light emitting device according to a first embodiment of the present invention. The device comprises a first electrode layer 4 formed on a substrate 2, which is an anode layer composed of indium tin oxide (ITO). The substrate may for example consist of a glass or flexible plastic substrate or may be a glass-plastic laminate. A first thin film 6 of luminescent organic material (in this case poly (phenylenevinylene) (PPV)) is formed on the ITO layer 4. This organic PPV layer 6 is formed by spin coating a PPV precursor in a suitable solvent onto the ITO layer 4 and then heating the spin coated layer to convert the precursor into a polymer PPV. A second thin film 8 of organic material (such as MEH-PPV) is formed over the first thin film 6 of the luminescent organic material. The second thin film 8 may be formed by a general method such as, for example, the first thin film 6 of the light emitting organic material. The second thin film of organic material may serve as a light emitting layer or a charge transport layer, or have any other purpose. In addition, light emitting organic layers may be provided.

Alternatively, the first thin film 6 of luminescent organic material may be a charge transport layer such as polyethylenedioxythiophene doped with polystyrene sulphonic acid (PEDT: PSS) or polyaniline doped with polystyrene sulfonic acid. The second thin film 8 may be made of 5% poly (2,7- (9,9-di) -ene (n) -octylfluorene-3,6- (benzodiadiazole). (benzothiadiazole)) and a mixture of 95% poly (2,7- (9,9-di-ene-octylfluorene) (5F8BT), poly (2,7- (9,9-di-ene-octylfluorene ) (F8), poly (2, 7- (9,9-di-ene-octylfluorene)-(1,4-phenylene-((4-methylphenyl) imino) -1,4-phenylene- ((4-methylphenyl) imino) -1,4-phenylene)) / poly (2,7- (9,9-di-ene-octylfluorene) (PFM: F8), poly (2, 7- (9,9-di-ene-octylfluorene)-(1,4-phenylene-((4-mesoxyphenyl) imino) -1,4-phenylene-((4-mesoxyphenylene) Imino) -1,4-phenylene)) / poly (2,7- (9,9-di-ene-octylfluorene) / poly (2,7- (9,9-di-ene-octyl Leuren)-(1,4-phenylene-((1,4-phenylene-((4-secbutylphenyl) imino) -1,4-phenylene)) (PFMO: F8: TFB It may be a light emitting layer such as).

A thin calcium layer 10 having a thickness of 200 nm is formed on the second thin film 8 of organic material. This calcium layer serves as a cathode and is formed by, for example, rf sputtering or dc magnetron sputtering (preferably using neon as the discharge gas), or vacuum deposition. Vacuum deposition is preferred because vacuum deposition is less damaging to the organic materials below when compared to sputtering techniques.

A thick aluminum nitride layer 12, about 10 μm thick, is formed over the thin calcium layer 10. This aluminum nitride layer 12 is preferably deposited by sputtering to provide a layer free of pinholes. With a sputter target / cathode made of aluminum and a discharge gas comprising nitrogen, conventional sputtering techniques such as rf sputtering or dc magnetron sputtering can be used.

The thick aluminum nitride layer 12 is markedly impermeable to materials such as oxygen and moisture present in the environment. This effectively protects the underlying cathode, ie, the calcium layer 10, from this reactive material.

2 shows an organic light emitting device according to a second embodiment of the invention. Same as the device of FIG. 1, except that an additional 5 μm thick aluminum layer 14 is provided as the second cathode layer between the thin calcium layer 10 and the thick aluminum nitride layer 12. In this case, this intermediate aluminum layer 14 is formed by vacuum deposition, but may alternatively be formed by, for example, sputtering techniques.

3 shows an organic light emitting device according to a third embodiment according to the present invention. It is similar to the device of FIG. 2 except that a thick aluminum oxide layer 16, about 10 μm thick, is formed over the thick aluminum nitride layer 12. The top layer 16 of this aluminum oxide is formed by sputtering techniques to provide a layer that does not contain pinholes.

4 shows an organic light emitting device according to a fourth embodiment of the invention. This device is the same as the device of FIG. 2 except that a second calcium layer 18 having a thickness of about 5 μm is provided between the aluminum layer 14 and the aluminum nitride layer 12. This second calcium layer 18 protects the underlying cathode by gettering any reactive materials that have penetrated the upper aluminum nitride layer 12. This second calcium layer 18 is preferably deposited by sputtering techniques to provide a layer that does not contain pinholes.

5 shows an organic light emitting device according to a fifth embodiment of the present invention. The device is an additional barrier layer, except that a sputtered aluminum layer 20 of about 10 μm thickness is provided between the vacuum deposited aluminum layer 14 and the second calcium layer 18, FIG. 4. Similar to the device of. According to the sixth embodiment shown in FIG. 6, an additional sputtered aluminum layer 22 is provided as an additional inert barrier layer between the second calcium layer 18 and the aluminum nitride layer 12.

7 shows an organic light emitting device according to a seventh embodiment of the invention. The device was fabricated with a 10 μm aluminum nitride layer 26 deposited by sputtering and a 1000 SiO SiO layer 24 thermally deposited from a hot ceramic boat, instead of the layers 12 and 16 of Ca / Al. Similar to FIG. 3 except that it is covered. In this embodiment, the cathode is covered with two layers of SiO / AlN, thereby protecting the cathode excellently. The reason is considered to be due to the fact that the SiO layer 24 serves not only as a physical barrier but also as a gettering layer which reacts with moisture to getter moisture.

Although the devices described above all describe the application of the invention in connection with the protection of the cathode, the invention can also be applied to the protection of the anode, or both the anode and the cathode.

Claims (32)

delete delete delete delete delete delete delete delete delete At least one light emitting organic material layer interposed between the first electrode and the second electrode, wherein the first and second electrodes and the light emitting organic material layer are all formed on a substrate, At least one of the first and second electrodes is formed on one side of the light emitting organic material at the outermost side away from the substrate and includes one or more electrode layers on the light emitting organic material layer for injecting charge carriers into the light emitting material. , And on the outermost electrode a stack of a first inert barrier layer and a SiO layer positioned between the outermost electrode layer and the first inert barrier layer to absorb moisture and oxygen. device. The organic light emitting device of claim 10, wherein the first inert barrier layer is a material layer selected from the group consisting of AlN, Al ₂ O ₃ , SiO ₂ and Si ₃ N ₄ . The organic light emitting device of claim 10, wherein the first inert barrier layer has a thickness in the range of 0.01 to 10 μm. 11. The organic light emitting device of claim 10, wherein the stack further comprises a second inert barrier layer positioned between the SiO layer and the surface of the outermost electrode layer away from the light emitting organic material layer. The organic light emitting device of claim 13, wherein the second inert barrier layer is a sputtered aluminum layer and the first inert barrier layer is an AlN layer. The organic light emitting device of claim 13, wherein the first and second inert barrier layers each have a thickness in the range of 0.01 to 10 μm. delete delete delete delete The organic light emitting device according to any one of claims 10 to 15, wherein the SiO layer has a thickness in the range of 0.01 to 5 mu m. 11. The method of claim 10, wherein at least one of the first and second electrodes comprises: a first low work function conductive layer on the light emitting organic material layer and a surface of the first low work function conductive layer away from the light emitting organic material layer. An organic light emitting device, characterized in that it is a multilayer electrode comprising a second conductive layer above. 22. The method of claim 21 wherein the first low work function conductive layer is a deposited calcium layer having a thickness of 200 nm or less and the second conductive layer is a deposited aluminum layer having a thickness of 5 μm or less. An organic light emitting device. delete delete delete delete delete delete delete delete delete delete