KR20230056372A - Oled having external light scattering layer with external light extracting quantum dots - Google Patents

Abstract

The present invention relates to an organic light-emitting device including an external light scattering layer containing quantum dots for extracting external light. The organic light-emitting device comprises: an organic light-emitting layer; a cathode; an anode; a substrate layer; an external light scattering layer; and a plurality of quantum dot bodies. According to the present invention, external light extraction efficiency can be improved.

Description

Organic light emitting device including an external scattering layer containing quantum dots for external light extraction {OLED HAVING EXTERNAL LIGHT SCATTERING LAYER WITH EXTERNAL LIGHT EXTRACTING QUANTUM DOTS}

The present invention relates to an OLED (Organic Light Emitting Diodes) product with increased external light extraction efficiency and a wide viewing angle.

OLEDs are attracting much attention as a next-generation display device due to their low power consumption, high color reproducibility, wide color gamut, fast response speed, and bendable characteristics. However, only about 20% of the light emitted from the OLED can be extracted from the display device, so the light extraction efficiency is greatly reduced. The reason for the low light extraction efficiency is that light is confined at the interface between the transparent electrode (ITO) layer and the substrate and at the interface between the substrate and air, which is due to the difference in refractive index of each material. In order to increase the light transmission efficiency between the substrate and the air, a Micro Lens Array (MLA) structure is mainly applied. This structure can cause color changes and interference colors depending on the viewing angle of the display panel, which increases the viewing angle of the display panel. I have a narrowing problem.

Republic of Korea Patent Registration No. 10-1735445 (Name: Laminate for OLED device using high refractive index and low refractive index organic/inorganic hybrid material and manufacturing method of OLED device, OLED device manufactured thereby, registration date: 2017.05.08.) PCT Publication No. WO2014-191733 (Name: Organic Light Emitting Diode Structure, publication date: 2014.04.12.)

An object of the present invention to solve the above problems is to increase the light extraction efficiency from the OLED device and to manufacture an OLED device that secures a wide viewing angle of a display panel.

Technical problems of the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

An organic light emitting device including an external scattering layer containing quantum dots for external light extraction according to an embodiment of the present invention for achieving the above object is an organic light emitting layer receiving electrons and holes to generate light of a specific wavelength, the organic light emitting layer A cathode formed on the top of the light emitting layer to supply electrons to the organic light emitting layer, an anode formed on the bottom of the organic light emitting layer to supply holes to the organic light emitting layer and transmitting light generated in the organic light emitting layer, A substrate layer formed at the bottom of the anode to transmit light generated from the organic light emitting layer to an external scattering layer, an external scattering layer formed at the bottom of the substrate layer to scatter light generated from the organic light emitting layer and emitting light to the outside, and It includes a plurality of quantum dots (Quantum Dot) bodies provided in a dispersed form within the external scattering layer and emitting light to the outside by increasing the intensity of light generated from the organic light emitting layer, wherein the external scattering layer forms a wrinkled structure to Includes an external scattering structure film that scatters light generated from the organic light emitting layer and emits light to the outside, and a plurality of scattering particle bodies provided in a dispersed form inside the external scattering structure film and emitting light to the outside by scattering light generated from the organic light emitting layer The external scattering structure film is a transparent nano structure formed by spin coating and curing a polymer composition on top of the substrate layer and then etching it with an ion etching method to form a concavo-convex structure. and a planarization member in which a concave-convex structure of the transparent nanostructure is changed into a flat wrinkled structure by depositing a metal oxide on the outside of the transparent nanostructure by a sputtering method, wherein the refractive index of the planarization member is the anode (Anode). It is characterized in that the refractive index of ) is equal to or greater than the refractive index of the anode.

In addition, the polymer composition according to the present invention includes polymethylmethacrylate (PMMA), and the metal oxide is characterized in that it includes ZnO.

In addition, it is characterized in that the wavelength range of light emitted from the plurality of quantum dot bodies according to the present invention is the same as the wavelength range of light emitted from the organic light emitting layer.

An organic light emitting device including an external scattering layer containing quantum dots for external light extraction according to an embodiment of the present invention can improve external light extraction efficiency by using the external light extraction quantum dots, and the external nano-scattering structure and scattering External light extraction efficiency is improved by applying an external scattering layer composed of complex particles, and color coordination change, a problem that occurs as the viewing angle increases when applying a Micro Lens Array (MLA) structure , it is possible to obtain the effect of reducing the color change phenomenon according to the viewing angle.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

1 is a diagram schematically showing the configuration of an organic light emitting device including an external scattering layer containing quantum dots for extracting external light according to an embodiment of the present invention.
2 is a diagram schematically illustrating a configuration of an external scattering layer according to an embodiment of the present invention.
3 is a view showing the shape of a transparent nanostructure among components of an external scattering structure film according to an embodiment of the present invention.
4 is a view showing a shape in which a planarization member is deposited on the outside of a transparent nanostructure among components of an external scattering structure according to an embodiment of the present invention.
5 is a graph illustrating a light extraction effect of an external scattering structure layer according to an embodiment of the present invention.
6 is a diagram illustrating a change in color coordination of an external scattering structure film according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings to the extent that those skilled in the art to which the present invention pertains can easily practice the present invention.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention without obscuring it by omitting unnecessary description.

For the same reason, in the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated. Also, the size of each component does not entirely reflect the actual size. In each figure, the same reference number is assigned to the same or corresponding component.

1 is a diagram schematically showing the configuration of an organic light emitting device including an external scattering layer containing quantum dots for extracting external light according to an embodiment of the present invention.

Referring to FIG. 1 , an organic light emitting device 10 including an external scattering layer containing quantum dots for extracting external light according to an embodiment of the present invention is an organic light emitting layer that generates light of a specific wavelength by receiving electrons and holes ( 100), a cathode 200 formed on the top of the organic light emitting layer 100 to supply electrons to the organic light emitting layer 100, and a cathode 200 formed on the bottom of the organic light emitting layer 100 to supply electrons to the organic light emitting layer 100 An anode 300 that supplies holes to and transmits light generated from the organic light emitting layer 100, and is formed at the bottom of the anode 300 to transmit light generated from the organic light emitting layer 100. The substrate layer 400, the external scattering layer 500 formed on the lower end of the substrate layer 400 and scattering the light generated in the organic light emitting layer 100 to emit light to the outside, and the inside of the external scattering layer 500 It may include a plurality of quantum dot bodies 600 provided in a dispersed form and emitting light to the outside by increasing the intensity of light generated from the organic light emitting layer 100 . The external scattering layer 500 forms a wrinkled structure to scatter light generated in the organic light emitting layer 100 and emits light to the outside, and is dispersed within the external scattering structure layer 510. It may include a plurality of scattering particle bodies 520 that are provided to emit light to the outside by scattering the light generated from the organic light emitting layer 100 .

According to an embodiment of the present invention, a wavelength range of light emitted from the plurality of quantum dot bodies 400 may be the same as a wavelength range of light emitted from the organic light emitting layer 100 .

2 is a diagram schematically illustrating a configuration of an external scattering layer according to an embodiment of the present invention.

Referring to FIG. 2 , the external scattering layer 500 forms a wrinkled structure to scatter light generated in the organic light emitting layer 100 and emits light to the outside. ) It may include a plurality of scattering particle bodies 520 provided in a dispersed form and emitting light to the outside by scattering the light generated in the organic light emitting layer 100.

According to an embodiment of the present invention, the plurality of scattering particle bodies 520 may be formed of particles selected from the group consisting of silicon-based, polymer-based, metal oxide-based, and mixtures thereof.

3 is a view showing the shape of a transparent nanostructure among components of an external scattering structure film according to an embodiment of the present invention.

Referring to FIG. 3 , the external scattering structure film is obtained by spin coating and curing a polymer composition on top of the substrate layer 400 and then etching it using an ion etching method to form a concavo-convex structure. A transparent nano structure 511 may be included.

According to one embodiment of the present invention, the polymer composition (not shown) may include polymethylmethacrylate (PMMA).

According to an embodiment of the present invention, the height of the transparent nanostructure 511 may vary according to the spin-coating speed of the polymer composition. Figure 3 (a) shows a spin coating speed of 1500 rpm, Figure 3 (b) shows a spin coating speed of 1750 rpm, Figure 3 (c) shows a spin coating speed of 2000 rpm, and Figure 3 (d) shows a spin coating speed. It may be the shape of the transparent nanostructure 511 when a coating speed of 2500 rpm is applied. The higher the spin coating speed, the lower the height of the wrinkle structure.

4 is a view showing a shape in which a planarization member is deposited on the outside of a transparent nanostructure among components of an external scattering structure according to an embodiment of the present invention.

Referring to FIG. 4 , a flattening member 512 is provided by depositing a metal oxide on the outside of the transparent nanostructure 511 by sputtering to change the concave-convex structure of the transparent nanostructure 511 into a flat wrinkled structure. can do.

According to an embodiment of the present invention, the refractive index of the flattening member 512 may be equal to or greater than the refractive index of the anode 300 .

According to one embodiment of the present invention, the metal oxide may include ZnO.

The refractive index of the flattening member 512 may be equal to or greater than the refractive index of the anode 300 . When the refractive index of the flattening member 512 is smaller than the refractive index of the anode 300, an additional waveguide mode in which light is reflected at the interface between the anode 300 and the flattening member 512 because it can be formed.

If the flattening member 512 is formed thickly, light absorption due to the flattening member 512 may occur, so the flattening member 512 may be formed as thin as possible. According to one embodiment of the present invention, the planarization member may be deposited to a thickness of 400 nm.

According to an embodiment of the present invention, the height of the wrinkle shape may vary according to the height of the transparent nanostructure 511 . Figure 4 (a) shows a spin coating speed of 1500 rpm, Figure 4 (b) shows a spin coating speed of 1750 rpm, Figure 4 (c) shows a spin coating speed of 2000 rpm, and Figure 4 (d) shows a spin coating speed. It may have a shape in which the planarization member 512 is deposited on the outside of the transparent nanostructure 511 formed by applying a coating speed of 2500 rpm.

5 is a graph illustrating a light extraction effect of an external scattering structure layer according to an embodiment of the present invention.

Since the external scattering structure layer 510 according to an embodiment of the present invention does not have experimental data, refer to the following experimental data, which is the result of conducting an experiment with respect to an internal scattering structure layer (not shown) formed in the same structure. can do.

According to an embodiment of the present invention with reference to FIGS. 3, 4, and 5, Device A forms the transparent nanostructure 511 by spin-coating the polymer composition on the substrate layer at 1750 RPM. It may be one sample. Device B may be a sample in which the transparent nanostructure 511 is formed by spin-coating the polymer composition on the substrate layer at 2000 RPM.

According to an embodiment of the present invention, the device A and the device B have low current efficiency at the front of the substrate layer 400 compared to the sample to which the micro cavity is applied, but measured at various viewing angles. It can be seen that the External Quantum Efficiency is large. This is because the wrinkle structure having the same shape as the wrinkle structure of the internal scattering structure film 510 forms the interface between the organic light emitting layer 100 and the anode 300 and the organic light emitting layer 100 and the cathode 200. It may be that the external quantum efficiency is increased by being transferred to the interface of .

Since the external scattering structure layer 510 according to an embodiment of the present invention has the same structure as the internal scattering structure layer (not shown), when the internal scattering structure layer is applied, the anode 300 and the substrate layer The result of the increased internal light extraction at the interface of (400) can also be applied to the external light extraction at the interface between the substrate layer 400 and external air.

FIG. 6 is a graph illustrating a shift of a peak wavelength and a change in color coordination when an internal scattering structure film is applied according to an embodiment of the present invention.

Since the external scattering structure layer 510 according to an embodiment of the present invention does not have experimental data, refer to the following experimental data, which is the result of conducting an experiment with respect to an internal scattering structure layer (not shown) formed in the same structure. can do.

Referring to FIG. 6, according to an embodiment of the present invention measured at a viewing angle of 60° from the front of the substrate layer 600, the device A and device B are compared with a sample to which a micro cavity is applied. , The shift of the peak wavelength is measured as 20 nm for device A and 26 nm for device B, compared to 42 nm when the micro cavity is applied, and only the micro cavity structure is applied and the internal scattering structure film 510 is not applied. It can be seen that it is reduced by 47% compared to the case without. The color coordination change was 0.165 when the microcavity was applied, whereas device A was 0.078 and device B was 0.087, which is more than when only the microcavity structure is applied and the internal scattering structure layer 510 is not applied. It can also be seen that it is reduced by 47%. In addition, it can be seen that the higher the height of the transparent nanostructure 511, the greater the improvement effect, considering that device A has a smaller peak wavelength shift and color coordination change value than device B.

Since the external scattering structure layer 510 according to an embodiment of the present invention has the same structure as the internal scattering structure layer (not shown), the result of the decrease in color coordination change value in the internal scattering structure layer is described above. It can also be applied to the external scattering structure layer 510 .

An organic light emitting device including an external scattering layer containing quantum dots for external light extraction according to an embodiment of the present invention can improve external light extraction efficiency by using the external light extraction quantum dots, and the external nano-scattering structure and scattering External light extraction efficiency is improved by applying an external scattering layer composed of complex particles, and color coordination change, a problem that occurs as the viewing angle increases when applying a Micro Lens Array (MLA) structure , it is possible to obtain the effect of reducing the color change phenomenon according to the viewing angle.

On the other hand, in the present specification and drawings, preferred embodiments of the present invention are disclosed, and although specific terms are used, they are only used in a general sense to easily explain the technical content of the present invention and help understanding of the present invention. It is not intended to limit the scope of the invention. It is obvious to those skilled in the art that other modified examples based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

100: organic light emitting layer
200: Cathode
300: Anode
400: substrate layer
500: external scattering layer
510: external scattering structure film
511: transparent nano structure
512: flattening member
520: scattering particle body
600: quantum dot body
10: organic light emitting device

Claims (3)

an organic light emitting layer receiving electrons and holes to generate light of a specific wavelength;
a cathode formed on top of the organic light emitting layer to supply electrons to the organic light emitting layer;
an anode formed at a lower end of the organic light emitting layer to supply holes to the organic light emitting layer and transmit light generated from the organic light emitting layer;
a substrate layer formed below the anode to transmit light generated from the organic light emitting layer to an external scattering layer;
an external scattering layer formed at a lower end of the substrate layer to emit light to the outside by scattering light generated from the organic light emitting layer; and
A plurality of quantum dots (Quantum Dot) bodies provided in a dispersed form inside the external scattering layer to increase the intensity of light generated from the organic light emitting layer to emit light to the outside;
The external scattering layer,
an external scattering structure film that forms a wrinkled structure to scatter light generated from the organic light emitting layer and emits light to the outside; and
A plurality of scattering particles provided in a dispersed form within the external scattering structure film to scatter light generated in the organic light emitting layer and emit light to the outside;
The external scattering structure film,
A transparent nano structure in which a polymer composition is spin-coated and cured on top of the substrate layer and then etched using an ion etching method to form a concavo-convex structure; and
A flattening member that changes the concave-convex structure of the transparent nanostructure into a flat wrinkled structure by depositing a metal oxide on the outside of the transparent nanostructure by a sputtering method,
The refractive index of the flattening member is,
An organic light emitting device comprising an external scattering layer containing quantum dots for external light extraction, characterized in that the refractive index of the anode is equal to or greater than the refractive index of the anode. According to claim 1,
The polymer composition,
Contains polymethylmethacrylate (PMMA),
The metal oxide,
An organic light emitting device comprising an external scattering layer containing quantum dots for external light extraction, characterized in that it comprises ZnO. According to claim 1,
An organic light emitting device comprising an external scattering layer containing quantum dots for extracting external light, characterized in that the wavelength region of light emitted from the plurality of quantum dot bodies is the same as the wavelength region of light emitted from the organic light emitting layer.

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