KR101248904B1 - Organic light emitting device, lighting equipment comprising the same, and organic light emitting apparatus comprising the same - Google Patents

Abstract

According to an aspect of the invention, the substrate; A first electrode located on the substrate; An organic light emitting layer disposed on the first electrode; A second electrode on the organic light emitting layer; And a first microlens array disposed between the substrate and the first electrode and having a refractive index greater than that of the substrate.

Description

Organic light emitting device, lighting equipment comprising the same, and organic light emitting apparatus comprising the same

The present invention relates to an organic light emitting device, an illumination device including an organic light emitting device, and a display device including an organic light emitting device, and more particularly, an organic light emitting device and an illumination including an organic light emitting device having improved external light extraction efficiency. An apparatus, and a display device including an organic light emitting element.

The present invention is derived from the research conducted as part of the electronic information device industrial source technology development project of the Ministry of Knowledge Economy and Korea University of Science and Technology Cooperation. [Task Management No .: 10035573-2010-01, Title: Selective Transparent Display Research through Display Structure Innovation]

In addition, the present invention is derived from a study carried out as part of the basic research project (leading research center development project) of the Ministry of Education, Science and Technology and Korea Advanced Institute of Science and Technology Cooperation. [Task Management No .: 20100009867, Title: Study on improving characteristics of flexible transparent organic light emitting device]

In the organic light emitting device, an organic light emitting layer is disposed between two opposing 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 light emitting layer are excited through the bonding. It is a light emitting device that emits energy emitted by light while returning to the ground state.

The light emitted from the light emitting layer of the organic light emitting device can be generally emitted in all directions in the light emitting layer, the light emitted at an angle greater than a certain critical angle is trapped inside the device by the total reflection phenomenon is not emitted to the outside of the device. . For this reason, the ratio of the number of photons reaching the actual observer without being consumed relative to the total number of photons generated in the light emitting layer of the organic light emitting element, that is, the outcoupling efficiency (η _out ), is determined by the organic light emitting element. Although there may be a difference depending on the value of the refractive index of each layer constituting, it is usually the situation is limited to less than about 15-20%.

Since the external light extraction efficiency of the organic light emitting device limits the overall external quantum efficiency and power efficiency, and the external quantum efficiency or power efficiency determines the overall power consumption of the organic light emitting device, and thus greatly affects the lifetime of the organic light emitting device. There have been efforts in many ways to increase this.

The present invention to solve the above problems and other problems, to provide an organic light emitting device having an improved external light extraction efficiency, an illumination device including an organic light emitting device, and an organic light emitting display device comprising an organic light emitting device. .

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 second electrode on the organic light emitting layer; And a first microlens array disposed between the substrate and the first electrode and having a refractive index greater than that of the substrate.

According to another feature of the invention, the substrate may comprise a translucent material.

According to another feature of the invention, the first electrode may comprise a translucent material.

According to another feature of the invention, the shape of the plurality of microlenses constituting the first microlens array may have a periodic pattern.

According to another feature of the invention, the periodic pattern may be greater than the wavelength of light emitted from the organic light emitting layer.

According to another feature of the invention, the shape of the plurality of microlenses constituting the first microlens array may have an aperiodic pattern.

According to another feature of the present invention, the plurality of microlenses may have a hemispherical shape, and the plurality of microlenses may form a constant contact angle with the first electrode.

According to another feature of the present invention, the first microlens array may include at least one material selected from oxides, nitrides, silicon compounds, sulfides, and polymer organic materials that are transparent to visible light.

According to another feature of the invention, an intermediate layer may be further provided between the first electrode and the first microlens array.

According to another feature of the invention, the refractive index of the intermediate layer may be greater than or equal to the refractive index of the first electrode.

According to another feature of the invention, the refractive index of the intermediate layer may be less than or equal to the refractive index of the first microlens array.

According to another feature of the invention, the intermediate layer to enhance the adhesion of the protective film, the planarization film or the first electrode and the first microlens array to prevent the penetration of the material between the first electrode and the first microlens array. It can be to.

According to another feature of the present invention, the plurality of microlenses may have a hemispherical shape, and the plurality of microlenses may form a constant contact angle with the intermediate layer.

According to another feature of the invention, the second microlens array may be further provided on the outside of the substrate.

According to another feature of the invention, the refractive index of the second microlens array may be equal to or larger than the refractive index of the substrate.

According to another feature of the invention, the shape of the plurality of microlenses constituting the second microlens array may have a periodic pattern, the periodic pattern may be larger than the wavelength of light emitted from the organic light emitting layer.

According to another feature of the invention, the shape of the plurality of microlenses constituting the second microlens array may have an aperiodic pattern.

According to another feature of the present invention, the plurality of microlenses may have a hemispherical shape, and the plurality of microlenses may form a constant contact angle with the substrate.

According to another feature of the present invention, an intermediate layer may be further provided between the second microlens array and the substrate.

According to another aspect of the present invention, there is provided a lighting device comprising the organic light emitting device described above.

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

According to the organic light emitting device according to one aspect of the present invention, by inserting a microlens array between the transparent electrode and the transparent substrate, it is possible to improve the light extraction efficiency by extracting the light of the light guide mode to the outside of the device without total reflection. .

Further, by additionally disposing a microlens array outside the transparent substrate, not only the light guide mode but also the light in the substrate trapped mode can be extracted to the outside of the device to further improve the light extraction efficiency.

1 is a cross-sectional view schematically showing an organic light emitting device according to a first embodiment of the present invention.
2 is a graph schematically showing a relationship between refractive index, contact angle, and light extraction efficiency of a first microlens array in an organic light emitting diode according to a first exemplary embodiment of the present invention.
3 is a graph schematically illustrating a relationship between a contact angle and light extraction efficiency according to some refractive indices of the first microlens array of FIG. 2.
4 is a schematic cross-sectional view of an organic light emitting diode according to a second exemplary embodiment of the present invention.
FIG. 5 is a graph schematically showing a relationship between refractive index, contact angle, and light extraction efficiency of a first microlens array in an organic light emitting diode according to a second exemplary embodiment of the present invention.
FIG. 6 is a graph schematically illustrating a relationship between a contact angle and light extraction efficiency according to some refractive indices of the first microlens array of FIG. 5.

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

1 is a cross-sectional view schematically showing an organic light emitting device according to a first embodiment of the present invention. Referring to the drawings, the organic light emitting device 100 according to the present embodiment includes a substrate 110, a first microlens array 120, an intermediate layer 170, a first electrode 130, an organic emission layer 140, And a second electrode 150.

The substrate 110 is transparently formed in the case of the bottom-emitting type organic light emitting device 100 in which light is emitted toward the substrate 110 as in the present embodiment. As such a transparent substrate, a glass substrate can be used.

The first electrode 130 and the second electrode 150 are disposed to face each other on the substrate 110, and at least one of the first electrode 130 and the second electrode 150 is formed to be transparent. In the case of the bottom emission type organic light emitting diode 100, at least the first electrode 130 may be provided as a transparent electrode, and the second electrode 150 may be provided as a reflective electrode. The first electrode 130 is a transparent electrode including a material selected from indium timing oxide (ITO), indium zinc oxide (IZO), ZnO, and In 2 O 3, and the second electrode 150 includes Li, Ca, LiF / Ca, and LiF. / Al, Al, Mg, Ag, Cs ₂ CO ₃ It may be provided as a reflective electrode containing a material selected from the compound.

The organic emission layer 140 is provided between the first electrode 130 and the second electrode 150. The organic light emitting layer 140 may be formed in a multilayer structure using various materials, and may further include an inorganic material layer. The organic light emitting layer 140 may be formed of a low molecular or high molecular organic material. The light emitted from the organic emission layer 140 is reflected by the second electrode 150, which is a reflective electrode, and is emitted to the transparent substrate 110 through the first electrode 130, which is a transparent electrode.

In general organic light emitting devices, light emitted at an angle greater than or equal to a certain critical angle is trapped in the organic light emitting layer and the transparent electrode (eg, ITO) layer in the organic light emitting device by total reflection and ultimately consumed in a waveguided mode. And (ii) are trapped inside the device by a substrate- confined mode, which is trapped on the substrate by total reflection between the substrate and the air layer and is not released to the outside of the device. For example, in the case of the bottom emission type, the ratio of the optical power reaching the actual user to the total optical power generated in the organic light emitting device is about 16%, and the remaining 84% is consumed because it cannot be extracted out of the organic light emitting device. It is a major cause of lowering the efficiency of the.

In order to solve the above problems, conventionally, an organic light emitting device in which a microlens array is applied to an outside of a side transparent substrate on which light is emitted is provided. However, the organic light emitting device having such a structure can extract light in the substrate trapped mode, but does not extract light in the light guide mode.

However, the organic light emitting diode 100 according to the present exemplary embodiment includes a first microlens array 120 having a plurality of microlenses disposed between the transparent substrate 110 and the transparent first electrode 130, thereby providing optical waveguide. It is configured to extract the light of the mode out of the device.

The first microlens array 120 is typically arranged so that a plurality of lenses have a periodic pattern or an aperiodic pattern on a plane, and may be formed in various distributions such as hexagonal dense structure and tetragonal lattice structure. In addition, the individual lenses in the first microlens array 120 may have various shapes such as hemispheres, pyramids / inverted pyramids, cones, etc., and the sizes of the individual lenses range from about several micrometers (μm) to several hundred micrometers (μm). It may vary depending on the actual use. When the first microlens array 120 has a periodic pattern, the periodicity is formed to be larger than the wavelength of emitted light, thereby reducing the wavelength dependency of light in the visible light region.

The first microlens array 120 preferably has a high refractive index. Here, the high refractive index means that the refractive index of the first microlens array 120 is higher than that of the transparent substrate 110. In addition, the refractive index of the first microlens array 120 may be smaller than the refractive index of the transparent first electrode 130 and the organic light emitting layer 140, but when the refractive index of the organic light emitting layer 140 is similar to or larger than the refractive index of the organic light emitting layer 140. It contributes a lot. The corresponding high refractive index first microlens array 120 may utilize oxides, nitrides, sulfides, or compounds containing them, including titanium oxide or zinc oxide, which is transparent to visible light, It can be produced using a variety of materials, such as gel, epoxy, resin.

An intermediate layer 170 may be provided between the first microlens array 120 and the transparent first electrode 130. The intermediate layer 170 may include a passivation layer, a planarization layer, or a layer of the first electrode 130 and the first microlens array 120 that prevents penetration of a material between the first electrode 130 and the first microlens array 120. It can function as a thin film for enhancing adhesion. The refractive index of the intermediate layer 170 may be greater than or equal to the refractive index of the first electrode 130 or less than or equal to the refractive index of the first microlens array 120.

On the other hand, when the hemispherical lens is applied, the plurality of microlenses constituting the first microlens array 120 contacts the intermediate layer 170 at a constant first contact angle θ1. The first contact angle θ1 is an angle formed by a tangent between the surface of the intermediate layer 170 and the hemispherical lens. When the hemispherical legs are formed to have a constant curvature, the first contact angle θ1 of the lens with respect to the surface of the intermediate layer 170 is Stays constant. Meanwhile, in the above embodiment, the first microlens array 120 is formed to be in direct contact with the intermediate layer 170. However, when the intermediate layer 170 is omitted or another layer is provided in addition to the intermediate layer 170, the first contact angle θ1 may be defined as an angle formed by the tangent of the lens and the surface of the layer in direct contact with the first microlens array 120.

According to the organic light emitting diode 100 according to the present embodiment, a first microlens array 120 having a relatively higher refractive index than the transparent substrate 110 is disposed between the substrate 110 and the first electrode 130. By inserting, the light of the optical waveguide mode propagating through the total reflection inside the first electrode 130 and the organic light emitting layer 140 may proceed to the first microlens array 120 without total reflection. Light transmitted to the first microlens array 120 is extracted toward the transparent substrate 110 with almost no total reflection due to the curvature of the lens structure. Of course, some of the light transmitted to the first microlens array 120 is again trapped in the substrate trapping mode, but the overall light extraction efficiency is higher than the amount of light extracted to the outside of the original device without the first microlens array 120. Is increased.

FIG. 2 is a graph schematically showing a relationship between the refractive index, the contact angle, and the light extraction efficiency of the first microlens array in the organic light emitting device according to the first embodiment of the present invention. 3 is a graph schematically illustrating a relationship between a contact angle and light extraction efficiency according to some refractive indices of the first microlens array of FIG. 2.

In the graph of FIG. 2, the refractive index of the first microlens array 120 is the x-axis, and the first contact angle θ1 of the hemispherical microlenses used is used as the y-axis as a parameter of the computer simulation.

The lens radius of the first microlens array 120 used in the computer simulation was 4 micrometers (μm) and arranged in a hexagonal dense structure. It can be seen through the computer simulation that the light extraction efficiency can be improved up to 3 times compared to the light extraction efficiency of the organic light emitting device of the conventional structure. This is much higher than the theoretical rise of 2.2 times when the first microlens array is used on the outer surface of the transparent substrate in the structure of the conventional organic light emitting device.

4 is a schematic cross-sectional view of an organic light emitting diode according to a second exemplary embodiment of the present invention. Referring to the drawings, the organic light emitting device 200 according to the present exemplary embodiment includes the second microlens array 260, the substrate 210, the first microlens array 220, the intermediate layer 270, and the first layer. The electrode 230, the organic emission layer 240, and the second electrode 250 are included.

Compared to the organic light emitting diode 100 according to the first embodiment described above, the organic light emitting diode 200 according to the present embodiment further includes a second microlens array 260 outside the substrate 210. That is, the present embodiment is a bottom emission type organic light emitting diode 200 in which the first and second microlens arrays 220 and 260 are simultaneously applied to the outside and the inside of the substrate 210. Therefore, the substrate 210 of the organic light emitting diode 200 according to the present exemplary embodiment is provided as a transparent substrate. In addition, the first electrode 230 may be provided as a transparent electrode, and the second electrode 250 may be provided as a reflective electrode. The organic light emitting layer 240 is provided between the first electrode 230 and the second electrode 250, and is formed between the first electrode 230 and the substrate 210 through which the light emitted from the organic light emitting layer 240 propagates. One microlens array 220 is provided. The intermediate layer 270 is provided between the first electrode 230 and the first microlens array 220, and the second microlens array 260 is provided outside the substrate 210. The refractive index of the intermediate layer 270 may be greater than or equal to the refractive index of the first electrode 230 or less than or equal to the refractive index of the first microlens array 220.

According to the organic light emitting device 200 according to the present exemplary embodiment, the first microlens array 220 having a relatively higher refractive index than the transparent substrate 210, as in the first exemplary embodiment described above, is provided with a substrate 320. ) Between the first electrode 230 and the first electrode 230, the light of the optical waveguide mode, which propagates through the total reflection inside the first electrode 230 and the organic emission layer 240, proceeds to the first microlens array 220 without total reflection. do. After passing through the first microlens array 220, some of the modes reaching the substrate 210 become a mode in which the substrate 210 is again trapped in the substrate 210, and the second microlens array 260 provided outside the substrate 210. ) Extracts a mode confined to the substrate 210 to the outside of the substrate 210, and thus, almost all light can be extracted to the outside of the device, not only the optical waveguide mode but also light of the substrate confined mode.

The refractive index of the second microlens array 260 is preferably made of a material that is equal to or slightly higher than that of the substrate 210. Also, like the first microlens array 220, the second microlens array 260 is arranged such that a plurality of lenses have a periodic pattern or an aperiodic pattern on a plane. Can be formed. In addition, individual lenses in the second microlens array 260 may have various shapes such as hemispheres, pyramids / inverse pyramids, cones, and the like. When the hemispherical lens is applied, the first microlens array 220 contacts the intermediate layer 270 at a constant first contact angle θ1, and the second microlens array 260 is fixed to the substrate 210. 2 Contact is made at the contact angle θ2.

On the other hand, although not shown in the figure, a protective film to prevent the penetration of the material between the substrate 210 and the second microlens array 260 between the second microlens array 260 and the substrate 210, planarization An intermediate layer (not shown) which may function as a film or a thin film for enhancing adhesion between the substrate 210 and the second microlens array 260 may be further provided. In this case, the refractive index of the intermediate layer (not shown) may be substantially the same as that of the substrate 210 and the second microlens array 260, so that the optical performance of the organic light emitting device 200 may not be degraded.

FIG. 5 is a graph schematically showing a relationship between the refractive index, the contact angle, and the light extraction efficiency of the first microlens array in the organic light emitting device according to the third embodiment of the present invention. 6 is a graph schematically illustrating a relationship between a contact angle and light extraction efficiency according to a part of a refractive index of the third microlens array of FIG. 5.

As the second microlens array 260 used in the simulation, lenses arranged in a hemispherical hexagonal dense structure having a radius of 50 micrometers (μm) having a second contact angle θ2 of 90 degrees and a refractive index of 1.7 were used. The refractive index of the first microlens array 220 provided between the first electrode 230 and the substrate 210 and the first contact angle θ1 of the used hemispherical microlenses were used as parameters of the computer simulation. In the case of optimized conditions, it can be seen from the computer simulation that the organic light emitting device 200 according to the first embodiment can improve the light extraction efficiency up to 4 times compared to the conventional organic light emitting device.

The above-described organic light emitting device having improved light extraction efficiency may be modified and applied in various forms within the scope of the technical idea of the present invention, and is not limited to the above embodiments. In addition, the embodiments and drawings are merely 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 conventional in the art to which the present invention belongs As those skilled in the art can make various substitutions, modifications, and changes without departing from the technical spirit of the present invention, it is not limited to the embodiments and the accompanying drawings. Judgment should be made including scope and equivalence.

100,200: organic light emitting device
110, 210: substrate
120 and 220: first microlens array group
130, 230: first electrode
140 and 240: organic light emitting layer
150, 250: second electrode
170, 270: middle layer
260: second microlens array group

Claims (21)

Board;
A first electrode located on the substrate;
An organic light emitting layer disposed on the first electrode;
A second electrode on the organic light emitting layer;
A first microlens array disposed between the substrate and the first electrode and having a refractive index greater than the refractive index of the substrate and greater than or equal to the refractive index of the organic light emitting layer; And
And an intermediate layer disposed between the first electrode and the first microlens array, the intermediate layer having a refractive index greater than or equal to the refractive index of the first electrode and less than or equal to the refractive index of the first microlens array. Claim 2 has been abandoned due to the setting registration fee. The method according to claim 1,
The substrate includes an organic light emitting device. Claim 3 has been abandoned due to the setting registration fee. The method according to claim 1,
The first electrode includes a light transmissive material. The method according to claim 1,
The shape of the plurality of microlenses constituting the first microlens array has an organic pattern. 5. The method of claim 4,
The periodic pattern is greater than the wavelength of light emitted from the organic light emitting layer. Claim 6 has been abandoned due to the setting registration fee. The method according to claim 1,
The shape of the plurality of microlenses constituting the first microlens array has an aperiodic pattern. The method according to claim 1,
The plurality of microlenses constituting the first microlens array has a hemispherical shape, and the plurality of microlenses forms a constant contact angle with the first electrode. The method according to claim 1,
The first microlens array includes at least one material selected from oxides, nitrides, silicon compounds, sulfides, and polymer organic materials transparent to visible light. delete delete delete The method according to claim 1,
The intermediate layer may be a passivation layer, a planarization layer, or a thin film for enhancing adhesion between the first electrode and the first microlens array to prevent penetration of a material between the first electrode and the first microlens array. The method according to claim 1,
The plurality of microlenses constituting the first microlens array has a hemispherical shape, and the plurality of microlenses form a constant contact angle with the intermediate layer. The method according to claim 1,
The organic light emitting device further comprises a second microlens array on the outside of the substrate. 15. The method of claim 14,
The refractive index of the second microlens array is equal to or larger than the refractive index of the substrate. 15. The method of claim 14,
The shape of the plurality of microlenses constituting the second microlens array has a periodic pattern, the periodic pattern is larger than the wavelength of light emitted from the organic light emitting layer. Claim 17 has been abandoned due to the setting registration fee. 15. The method of claim 14,
The shape of the plurality of microlenses constituting the second microlens array has an aperiodic pattern. 15. The method of claim 14,
The plurality of microlenses constituting the second microlens array has a hemispherical shape, and the plurality of microlenses form a constant contact angle with the substrate. 15. The method of claim 14,
An organic light emitting device further comprising an intermediate layer between the second microlens array and the substrate. An illumination device comprising the organic light emitting device of claim 1. An organic light emitting display device comprising the organic light emitting device of claim 1.

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