KR102226632B1 - Enhanced out-coupling efficiency of quantum dots light emitting devices using nanoporous templates and method of manufacturing the same - Google Patents

Abstract

The present invention provides a method of manufacturing a light emitting device. According to an embodiment, (a) disposing a block copolymer layer on the first electrode; (b) phase-separating the materials contained in the block copolymer layer; (c) forming a plurality of holes in the block copolymer layer by removing a specific material from among the materials separated through the phase separation; And (d) disposing an electron transfer layer including an electron transfer plate disposed on the block copolymer layer and an electron transfer protrusion extending from the bottom surface of the electron transfer plate to the first electrode through the hole; do.

Description

Quantum dot light emitting device with increased external emission efficiency using nanoporous substrate and its manufacturing method {ENHANCED OUT-COUPLING EFFICIENCY OF QUANTUM DOTS LIGHT EMITTING DEVICES USING NANOPOROUS TEMPLATES AND METHOD OF MANUFACTURING THE SAME}

The present invention relates to a quantum dot light emitting device with increased external emission efficiency and a method of manufacturing the same using a nanoporous substrate.

Quantum Dot (QD) is a semiconductor nanoparticle. Quantum dots with a diameter of nanometers emit light as electrons in an unstable state descend from the conduction band to the valence band. The smaller the particle of the quantum dot, the shorter wavelength light is generated, and the larger the particle, the longer wavelength light is generated. This is a unique electrical and optical property that is different from conventional semiconductor materials. Therefore, when the size of the quantum dot is adjusted, visible light of a desired wavelength can be expressed, and various colors can be simultaneously realized by varying the quantum dot and the quantum dot component of various sizes.

A typical quantum dot light emitting device includes an anode and a cathode facing each other on a substrate, a quantum emission layer formed between the anode and the cathode, a hole transport layer formed between the anode and the quantum emission layer, and an electron transport layer formed between the quantum emission layer and the cathode. It is made including.

A typical organic light-emitting display device uses an organic light-emitting material as a material for the emission layer, and an organic light-emitting diode (OLED) using an organic light-emitting material implements a single color such as white, red, and blue depending on the type of device. , There is a limit to expressing a lot of light colorfully.

On the other hand, a quantum dot light emitting device is a display device that uses quantum dots as a material for the light emitting layer, and it can realize a desired natural color by controlling the size of the quantum dot, and it has good color reproducibility and does not lag behind light emitting diodes, thus attracting attention as a next generation light source. It is in the spotlight as a material that can make up for the shortcomings of LEDs (Light Emitting Diode).

However, in the case of a quantum dot light emitting device, the external luminous efficiency is only about 3%. Therefore, there is a need for a new method for improving the external luminous efficiency of the quantum dot light emitting device.

The present invention is to provide a method for manufacturing a light emitting device that improves external luminous efficiency through a plurality of holes formed by using the phase separation and self-assembly characteristics of a block copolymer.

The present invention is to provide a light emitting device having improved external luminous efficiency through a plurality of holes formed by using the phase separation and self-assembly characteristics of a block copolymer.

The present invention provides a method of manufacturing a light emitting device. According to an embodiment, (a) disposing a block copolymer layer on the first electrode; (b) phase-separating the materials contained in the block copolymer layer; (c) forming a plurality of holes in the block copolymer layer by removing a specific material from among the materials separated through the phase separation; And (d) disposing an electron transfer layer including an electron transfer plate disposed on the block copolymer layer and an electron transfer protrusion extending from the bottom surface of the electron transfer plate to the first electrode through the hole; do.

In the step (a), a polymer layer is disposed on the first electrode, a block copolymer layer is disposed on the polymer layer, and the step (c) is performed by removing a specific material among the phase-separated materials. It may include forming a plurality of holes in the block copolymer layer, and exposing a region corresponding to the position of the hole of the first electrode by removing the region of the polymer layer exposed by the hole.

After the step (d), (e) disposing a quantum dot emission layer including quantum dots on the electron transport layer; may further include.

The specific material may be removed by immersing the block copolymer layer in a solvent that selectively removes the specific material.

The block copolymer layer may be polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP).

The specific material may be P2VP (poly(2-vinylpyridine) copolymer).

The polymer layer may be PVA (Polyvinyl Alcohol).

The polymer layer, the block copolymer layer, and the electron transport layer are selected from among a spin-coating method, a dip coating method, a roll-to-roll method, and a doctor blade method. It can be deployed using either.

The present invention provides a light emitting device. According to an embodiment, a first electrode; A porous substrate layer disposed on the first electrode and including a plurality of holes; And an electron transfer layer including an electron transfer plate disposed on the porous substrate layer and an electron transfer protrusion extending from the bottom surface of the electron transfer plate to the first electrode through the hole.

It may further include a quantum dot emission layer disposed on the electron transport layer and including quantum dots.

The method of manufacturing a light emitting device according to an embodiment of the present invention may be provided to improve external luminous efficiency through a plurality of holes formed by using the phase separation and self-assembly characteristics of the block copolymer.

In addition, the light emitting device according to an embodiment of the present invention may improve external luminous efficiency through a plurality of holes formed by using the phase separation and self-assembly characteristics of the block copolymer.

1 is a flowchart of a method of manufacturing a light emitting device according to an embodiment of the present invention.
2 is a cross-sectional view showing step S10 of FIG. 1.
3 is a cross-sectional view showing step S20 of FIG. 1.
4 is a cross-sectional view showing step S30 of FIG. 1.
5 is a cross-sectional view showing step S40 of FIG. 1.
6 is a flowchart of a method of manufacturing a light emitting device according to another embodiment of the present invention.
7 is a perspective view showing each step of the method of manufacturing the light emitting device of FIG. 6.
8 is a cross-sectional view showing step S11 of FIG. 6.
9 is a cross-sectional view showing step S12 of FIG. 6.
10 is a cross-sectional view showing step S20 of FIG. 6.
11 is an SEM image of the block copolymer in step S20.
12 is a cross-sectional view showing step S30 of FIG. 6.
13 is an SEM image of the block copolymer in step S30 of FIG. 6.
14 is a cross-sectional view showing step S31 of FIG. 6.
15 is a cross-sectional view showing step S40 of FIG. 6.
16 is a perspective view of the bottom of the electron transport layer of FIG. 15.
17 is an SEM image of the bottom surface of the electron transport layer of FIG. 16.
18 is a perspective view showing each step of a method of manufacturing a quantum dot light emitting device according to another embodiment of the present invention.
19 is a perspective view showing an exploded view of the quantum dot light emitting device of FIG. 18.
20 is a graph showing luminance and current density characteristics according to voltage of the quantum dot light emitting device of the present invention.
21 is a graph showing external quantum efficiency and current efficiency characteristics according to the current density of the quantum dot light emitting device of the present invention.
22 is a graph showing external quantum efficiency and current efficiency according to the current density of the quantum dot light emitting device of the present invention.
23 is a graph showing the emission spectrum of the quantum dot light emitting device of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following embodiments. This embodiment is provided to more completely describe the present invention to those with average knowledge in the art. Therefore, the shape of the element in the drawings is exaggerated to emphasize a more clear description.

The configuration of the invention for clarifying the solution to the problem to be solved by the present invention will be described in detail with reference to the accompanying drawings based on a preferred embodiment of the present invention, but the same in assigning reference numerals to the components of the drawings For components, even though they are on different drawings, the same reference numerals are given, and it is to be noted in advance that components of other drawings may be referred to when necessary when describing the drawings.

The present invention uses the phase separation and self-assembly of the block copolymer 21 to arrange the porous substrate 20 having the cylindrical hole 23 on the transparent electrode 10 of the quantum dot light emitting device, thereby improving external luminous efficiency. It's about technology to improve.

In the case of the conventional quantum dot light emitting device, there is a problem in that the external luminous efficiency is low. However, in the case of the present invention, external luminous efficiency can be increased by disposing the porous substrate 20 on the first electrode 10 which is a transparent electrode.

For example, a porous substrate 20 is disposed on the first electrode 10. The porous substrate 20 includes a polymer layer 22 disposed on the first electrode 10 and a block copolymer layer 21 disposed on the polymer layer 20.

Thereafter, a plurality of dispersed cylindrical patterns are formed in the block copolymer layer 21 through a solvent annealing process in which the block copolymer layer 21 is exposed to a solvent. The pattern may be vertically oriented on the substrate.

Then, the pattern is removed by dipping into a solution that selectively removes the pattern. When the plurality of dispersed cylindrical patterns formed in the block copolymer layer 21 are removed, a plurality of holes 23 are formed in the block copolymer layer 21. The hole may be a plurality of distributed cylindrical holes 23 vertically oriented on the substrate.

Thereafter, when plasma etching is performed on the polymer layer 22 and the block copolymer layer 21, a region of the polymer layer 22 corresponding to the position of the hole 23 is etched.

Thereafter, when the electron transfer material is coated on the block copolymer layer 21, the electron transfer material is disposed inside the electron transfer plate 31 and the hole 23 disposed on the block copolymer layer 21. The electron transport layer 30 including the electron transport protrusion 32 is formed.

Thereafter, a quantum dot emission layer 40, a hole transport layer 50, a hole injection layer 60, and a second electrode 70 are disposed on the electron transport layer 30. As a result, a quantum dot light emitting device including a porous substrate 20 having a nano-sized hole 32 and an electron transport layer 30 positioned above the porous substrate 20 and inside the hole 23 You can get it.

Hereinafter, the present invention will be described in detail with reference to the drawings. 1 is a flowchart of a method of manufacturing a light emitting device according to an embodiment of the present invention. According to an embodiment, the block copolymer layer 21 includes holes 23. The hole may be a plurality of distributed cylindrical holes 23 vertically oriented on the substrate.

Referring to FIG. 1, the method of manufacturing a light emitting device includes disposing a block copolymer layer 21 on the first electrode 10 (S10), and causing a phase separation phenomenon in the block copolymer layer 21 (S20). , Step of forming a plurality of holes 23 by removing a specific material among the phase-separated materials (S30), and an electron transfer layer 30 on the top of the block copolymer layer 21 and inside the hole 23 ) And placing (S40).

2 is a cross-sectional view showing step S10 of FIG. 1. Referring to FIG. 2, a block copolymer layer 21 is disposed on the first electrode 10. For example, the first electrode 10 may be formed of a transparent electrode material such as ITO (indium tin oxide), and may be disposed on the glass substrate 11.

For example, the block copolymer layer 21 shown in FIG. 2 may be formed of polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP), and prepared by using a solution process such as spin coating. 1 It may be coated on the electrode 10.

3 is a cross-sectional view showing step S20 of FIG. 1. Referring to FIG. 3, when solvent annealing in which the block copolymer layer 21 is exposed to a solvent is performed, the block copolymer layer 21 forms a pattern through phase separation and self-assembly processes.

For example, the solvent annealing may be performed using toluene. In the case of the block copolymer layer 21 made of PS-b-P2VP, when the solvent annealing process is performed, a phase separation phenomenon occurs into the PS region and the P2VP region. At this time, phase separation is performed in a spherical, cylindrical, and lamella (plate) type according to the volume fraction of PS and P2VP.

For example, the volume fraction of PS may be set to 0.7, and the volume fraction of P2VP may be set to 0.3. In this case, a PS having a large volume fraction forms the matrix region 21a, and a P2VP having a relatively small volume fraction is a domain region 21b consisting of a plurality of cylindrical patterns vertically oriented on the substrate in a matrix composed of PS. To form.

4 is a cross-sectional view showing step S30 of FIG. 1. Referring to FIG. 4, the specific material may be removed by immersing the phase-separated block copolymer layer 21 in a solvent that selectively removes the specific material. For example, when the block copolymer layer 21 in which the PS-b-P2VP is used is immersed in an ethanol solvent, the domain region 21b made of P2VP dissolved in ethanol is selectively swollen. At this time, P2VP diffuses into the ethanol phase, but due to the chemical structural characteristics of the block copolymer, the P2VP molecules are not completely dissolved in ethanol, and one end of the P2VP molecule remains fixed in the PS layer, which is a matrix. Thereafter, when a rapid gas flow using nitrogen or the like is given, P2VP is extracted from the domain region 21b due to rapid ethanol removal, and a cylindrical hole 23 in the portion occupied by the domain region 21b. Is formed.

The diameter of the hole 23 is proportional to the diameter of the existing cylindrical nano pattern. Therefore, when the block copolymer 21 having a large molecular weight is used, the diameter of the hole 23 can be increased, and when a block copolymer 21 having a small molecular weight is used, the diameter of the hole 23 can be reduced. .

When the size of the molecule of the block copolymer is substantially reduced, the size of the hole 23 may be smaller than 10 nanometers. However, when the molecular weight is very small, phase separation does not occur easily. In addition, when the molecular weight of the block copolymer is very large, sufficient fluidity cannot be applied to the block copolymer layer 21 during solvent annealing. Accordingly, the diameter of the hole 23 is preferably between 10 nanometers and 200 nanometers, more preferably 60 nanometers.

5 is a cross-sectional view showing step S40 of FIG. 1. Referring to FIG. 5, an electron transport layer 30 is disposed above the block copolymer layer 21 and inside the hole 23. The electron transfer layer 30 includes an electron transfer plate 31 disposed on the block copolymer layer 21 and an electron transfer protrusion 32 disposed inside the hole 23.

The electron transport layer 30 may be disposed by coating an electron transport material on the block copolymer layer 21. The coating method may be any one of a spin-coating method, a dip coating method, a roll-to-roll method, and a doctor blade method, preferably A spin-coating method may be used.

For example, zinc oxide may be used as the electron transport material. When zinc oxide is spin-coated on the block copolymer layer 21, the zinc oxide is applied on the top of the block copolymer layer 21 to form the electron transfer plate 31, and is injected into the hole 33. Is formed to form the electron transfer protrusion (32). The electron transfer protrusion 32 extends from the bottom surface of the electron transfer plate 31 to a place in contact with the first electrode 10.

The length of the electron transfer protrusion 32 affects the external luminous efficiency of the light emitting device and may be adjusted according to the coating thickness of the block copolymer layer 21.

6 is a flowchart of a method of manufacturing a light emitting device according to another embodiment of the present invention. According to another embodiment of the present invention, the step of disposing the polymer layer 22 on the first electrode 10 (S11), the step of disposing the block copolymer layer 21 on the polymer layer 22 (S12) , The step of causing a phase separation phenomenon in the block copolymer layer 21 (S20), the step of forming a plurality of holes 23 by removing a specific material among the phase-separated materials (S30), exposure by the hole 23 Exposing the region of the first electrode 10 corresponding to the position of the hole 23 by removing the region of the polymer layer 22 (S31), and the upper portion and the hole 23 of the block copolymer layer 21 It includes a step (S40) of arranging the electron transport layer 30 in the inside of.

7 is a perspective view showing each step of the method of manufacturing the light emitting device of FIG. 6. Referring to FIG. 7, a first electrode 10, a polymer layer 22, and a block copolymer layer 21 are disposed on a substrate. The glass substrate 11 may be used as the substrate.

When the block copolymer layer 21 is phase-separated into a domain region 21b having a plurality of dispersed cylindrical patterns and other matrix regions 21a and the domain region 21b is removed, the block copolymer layer 21 A plurality of cylindrical holes 23 are formed. Subsequently, when plasma etching is performed, a region corresponding to the hole 23 on the polymer layer 22 is removed, and thus a cylindrical hole penetrating the upper surface of the block copolymer layer 21 and the bottom surface of the polymer layer 22 (23) is formed.

Through this process, the porous substrate 20 is formed on the first electrode 10. Thereafter, when a conductive material is coated on the porous substrate 20, the electron transfer plate 31 disposed on the porous substrate 20 and the electron transfer protrusion 32 disposed inside the hole 23 are formed. The included electron transport layer 30 is disposed.

8 is a cross-sectional view showing step S11 of FIG. 6. Referring to FIG. 8, the polymer layer 22 may be disposed on the first electrode 10 through a coating method.

The coating may be any one of a spin-coating method, a dip coating method, a roll-to-roll method, and a doctor blade method, preferably spin Coating (Spin-Coating) method can be used. The polymer layer 22 may be PVA (Polyvinyl Alcohol).

9 is a cross-sectional view showing step S12 of FIG. 6. Referring to FIG. 9, the block copolymer layer 21 may be disposed on the polymer layer 22 through a coating method.

The coating may be any one of a spin-coating method, a dip coating method, a roll-to-roll method, and a doctor blade method, preferably spin Coating (Spin-Coating) method can be used.

The block copolymer layer 21 may be PS-b-P2VP.

10 is a cross-sectional view showing step S20 of FIG. 6, and FIG. 11 is a photograph taken with an atomic force microscope of the block copolymer layer 21 of step S20. Step S20 included in FIGS. 10 and 11 is the same as the content of S20 described above.

12 is a cross-sectional view showing step S30 of FIG. 6, and FIG. 13 is a photograph of the block copolymer of step S30 of FIG. 6 taken with an atomic force microscope. Step S30 included in FIGS. 12 and 13 is the same as the content of S30 described above.

14 is a cross-sectional view showing step S31 of FIG. 6. Referring to FIG. 14, the region of the polymer layer 22 exposed by the hole 23 is removed by plasma etching, whereby the hole 23 is formed on the upper surface of the block copolymer layer 21 and the polymer layer 22. It penetrates the bottom of ). As the plasma etching, oxygen plasma etching may be used.

As the hole 23 penetrates not only the block copolymer layer 21 but also the polymer layer 22, a region corresponding to the position of the hole 23 of the first electrode 10 is exposed.

The polymer layer 22 may be provided with PVA.

When plasma etching is performed on the polymer layer 22 and the block copolymer layer 21, not only the polymer layer 22 but also the block copolymer layer 21 are etched at the same time. However, PS, P2VP and PVA differ in the rate at which they are etched by plasma. Therefore, even if plasma etching is performed for the same time, the matrix region 21a of the block copolymer layer 21 composed of P2VP serves as a mask.

In the case of the polymer layer 22, the area protected by the mask is not etched, and the area exposed by the hole 23 is etched. As a result, the hole 23 penetrates the polymer layer 22 and reaches the first electrode 10.

In general, the size of the hole 23 can be adjusted together by adjusting the size of the molecular weight constituting the block high polymer 21. In addition, the size of the hole 23 may be adjusted during the plasma etching process.

When plasma etching is performed, not only the domain region 21b and the polymer layer 22 of the block copolymer layer 21, but also the matrix region 21a of the block copolymer layer 21 may be etched. Accordingly, the size of the hole 23 included in the porous substrate 20 can be adjusted by controlling the time for performing the plasma etching.

In addition, most of the domain regions 21b were removed by immersing the domain regions 21b of the block copolymer layer 21 in a solution that selectively removes them, but nonetheless, the domain regions 21b that remained in the block copolymer layer 21 in a small amount. ) Is also removed through plasma etching, thereby obtaining a porous substrate 20 having a plurality of cylindrical holes 23.

That is, a porous substrate 20 including a plurality of vertically oriented cylindrical holes 23 is formed on the substrate through the plasma etching process.

15 is a cross-sectional view showing step S40 of FIG. 6. 16 is a perspective view of the bottom surface of the electron transport layer 30 of FIG. 15. 17 is a photograph of the bottom surface of the electron transport layer 30 of FIG. 16 taken with an atomic force microscope. 15, 16, and 17, the electron transfer layer 30 includes an electron transfer plate 31 disposed on the block copolymer layer 21 and an electron transfer protrusion disposed inside the hole 33 ( 32).

The electron transfer protrusion 32 extends from the bottom surface of the electron transfer plate 31 and contacts the first electrode 10. The electron transport layer 30 is made of a conductive material and is disposed on the block copolymer layer 21 in a coating manner.

The coating may be any one of a spin-coating method, a dip coating method, a roll-to-roll method, and a doctor blade method, preferably spin Coating (Spin-Coating) method can be used.

The electron transport layer 30 serves to transfer electrons introduced from the first electrode 10 to the emission layer 40. When the block copolymer layer 21a is present on the first electrode 10 without the polymer layer 22, the length of the electron transfer protrusion 32 is formed to be about 10 nanometers. However, when the polymer layer 22 is added, the length of the electron transport protrusion 32 is as long as the height of the polymer layer 22.

When the length of the electron transfer protrusion 32 becomes longer, the path through which light generated inside the light emitting device passes through the electron transfer protrusion 32 becomes longer, thereby increasing the external luminous efficiency.

In general, the external luminous efficiency of the light emitting device is about 3%. However, by disposing the electron transport layer 30 including the electron transport protrusion 32, external luminous efficiency can be improved to 3.6%.

Since the thickness of the electron transport layer 30 is fixed, as the electron transport protrusion 32 becomes longer, the roughness of the surface of the electron transport plate 31 increases. This increases the surface roughness of the material deposited on the electron transport layer 30. This increase in surface roughness impairs the stability of the light emitting device, thereby increasing the current density value, which reduces the external luminous efficiency of the light emitting device. Therefore, it is preferable that the length of the electron transfer protrusion 32 does not exceed 50 nanometers.

The electron transport layer 30 may be separated from the porous substrate 20. After separating the electron transport layer 30 from the porous substrate 20, it can be applied not only to the light emitting device of the present invention, but also to other types of light emitting devices. Through this, external luminous efficiency of other types of light emitting devices can be improved.

18 is a perspective view showing each step of a method of manufacturing a quantum dot light emitting device according to another embodiment of the present invention. 19 is a perspective view showing an exploded view of the quantum dot light emitting device of FIG. 18. 18 and 19, a quantum dot light emitting device is obtained by arranging a quantum dot light emitting layer 40, a hole transport layer 50, a hole injection layer 60, and a second electrode 70 on the electron transport layer 30. I can.

The quantum dot light emitting device according to the present invention includes a first electrode 10. The first electrode 10 may be formed on the glass substrate 11. The first electrode 10 may be formed of a transparent electrode material such as ITO.

A porous substrate 20 is disposed on the first electrode 11. The porous substrate 20 may include both the block copolymer layer 21 and the polymer layer 22, or may include only the block copolymer layer 21. The porous substrate 20 includes a plurality of cylindrical holes 23. The hole 23 penetrates through the upper and lower surfaces of the porous substrate 20.

The electron transport layer 30 is disposed on the porous substrate 20. The electron transfer layer includes an electron transfer plate 31 disposed on the porous substrate 20 and an electron transfer protrusion 32 disposed inside the hole 23. The electron transfer protrusion 33 extends from the bottom surface of the electron transfer plate 31 and contacts the first electrode 11.

On the electron transport layer 30, a quantum dot emission layer 40, a hole transport layer 50, a hole injection layer 60, and a second electrode 70 may be sequentially disposed from the bottom to the top.

The quantum dot emission layer 40 may be changed to an organic emission layer, and when the quantum dot emission layer 40 is changed to an organic emission layer, the light emitting device of the present invention operates as an organic light emitting device.

<Measurement result>

Hereinafter, luminance, current density, external luminous efficiency, current efficiency, power efficiency, and emission spectrum of a light emitting device according to an exemplary embodiment of the present invention will be described in comparison with a comparative example with reference to FIGS. 20 to 23.

Comparative Example (Reference)

The comparative example was set with a light emitting device that does not contain a porous substrate.

Example

In Examples, the thickness of the porous substrate was selected to be 15 nm and 40 nm. The thickness of the porous substrate corresponds to the length of the electron transport protrusion.

External Quantum Effieiency is defined as the number of photons emitted into free space per second divided by the number of electrons injected into the LED per second,

The internal quantum efficiency is defined as the number of photons emitted from the active region per second divided by the number of electrons injected into the led per second,

The extraction efficiency, which is the degree to which a photon can escape to the outside, is defined as the number of photons emitted into free space per second as the number of photons emitted from the active area per second.

At this time, the number of electrons injected into the LED per second means the current density.

20 is a graph showing luminance and current density characteristics according to voltage of the quantum dot light emitting device of the present invention.

Referring to FIG. 20, the luminance and current density characteristics according to voltage were confirmed when the porous substrate as a reference was not provided and when the thickness of the porous substrate as an example was 15 nm and the thickness of the porous substrate was 40 nm. I can.

As shown in Fig. 20, compared to the comparative example, in the case of the example, it can be seen that the luminance is low, but at the same time, the current density is also low. You can see the lowest one.

Since the external quantum efficiency is inversely proportional to the current density, the external quantum efficiency is greatest when the thickness of the porous substrate is 15 nm. Therefore, it is most preferable that the thickness of the porous substrate is 15 nm.

21 is a graph showing external quantum efficiency and current efficiency characteristics according to the current density of the quantum dot light emitting device of the present invention.

Referring to FIG. 21, external quantum efficiency and current efficiency according to the current density when the porous substrate as a reference is not provided and when the thickness of the porous substrate is 15 nm and the thickness of the porous substrate is 40 nm. You can check the characteristics.

As shown in FIG. 21, in the case of the comparative example, the external quantum efficiency was 3%, whereas the external quantum efficiency when the porous substrate had a thickness of 15 nm was 3.6%, and the external quantum efficiency was improved by about 20% compared to the comparative example. You can see that it is imported. In addition, it can be seen that the current efficiency is also the greatest when the thickness of the porous substrate is 15 nm. Therefore, it is most preferable that the thickness of the porous substrate is 15 nm.

22 is a graph showing external quantum efficiency and current efficiency according to the current density of the quantum dot light emitting device of the present invention.

Referring to FIG. 22, it can be seen that power efficiency is increased when the thickness of the porous substrate is 15 nm as compared with the comparative example.

23 is a graph showing the emission spectrum of the quantum dot light emitting device of the present invention.

Referring to FIG. 23, it can be seen that there is little difference in spectrum even when the porous substrate is added as compared with the comparative example. In order to increase the external luminous efficiency, the conventional external lens attachment method has a problem of causing light bleeding. However, in the case of the embodiment of the present invention, it can be seen that the emission spectrum is almost identical to the case in which the porous substrate is not present, so that it is possible to prevent the phenomenon of debt spread.

As can be seen from the above, a porous substrate 20 including a cylindrical hole penetrating the upper surface of the block copolymer layer 21 and the lower surface of the polymer layer 22 on the first electrode 11 is disposed, and , External luminous efficiency of the quantum dot light emitting device may be improved through the electron transport layer 30 disposed on the upper surface of the porous substrate 20 and inside the hole 32.

The detailed description above is illustrative of the present invention. In addition, the above description shows and describes preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, changes or modifications may be made within the scope of the concept of the invention disclosed in the present specification, the scope equivalent to the disclosed contents, and/or the skill or knowledge of the art. The above-described embodiments describe the best state for implementing the technical idea of the present invention, and various changes required in the specific application fields and uses of the present invention are also possible. Therefore, the detailed description of the invention is not intended to limit the invention to the disclosed embodiment. In addition, the appended claims should be construed as including other embodiments.

10: first electrode 11: glass substrate
20: porous substrate 21: block copolymer layer
21a: matrix area 21b: domain area
22: polymer layer 23: hole
30: electron transport layer 31: electron transport plate
32: electron transport protrusion 40: quantum dot emitting layer
50: hole transport layer 60: hole injection layer
70: second electrode

Claims (16)

A first electrode;
A porous substrate layer disposed on the first electrode and including a plurality of holes;
Including; an electron transfer layer including an electron transfer plate disposed on the porous substrate layer and an electron transfer protrusion extending from the bottom surface of the electron transfer plate to the first electrode through the hole,
The porous substrate layer is:
A polymer layer formed on the bottom surface; And
A light emitting device comprising a block copolymer layer formed on the upper surface.
delete The method of claim 1,
The polymer layer is a light emitting device containing PVA (Polyvinyl Alcohol).
The method of claim 3,
The block copolymer layer is a light emitting device formed by removing poly(2-vinylpyridine) copolymer (P2VP) from polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP).
The method of claim 4,
In the polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP), the volume fraction of PS is 0.7, and the volume fraction of P2VP is 0.3.
The method of claim 4,
The hole is a light emitting device corresponding to a region occupied by the poly(2-vinylpyridine) copolymer (P2VP).
The method of claim 6,
The diameter of the hole is a light emitting device of 60 nanometers.
The method of claim 1,
A light emitting device further comprising a; quantum dot light emitting layer disposed on the electron transport layer and including quantum dots.
(a) disposing a block copolymer layer on the first electrode;
(b) phase-separating the materials included in the block copolymer layer;
(c) forming a plurality of holes in the block copolymer layer by removing a specific material from among the materials separated through the phase separation; And
(d) disposing an electron transfer layer including an electron transfer plate disposed on the block copolymer layer and an electron transfer protrusion extending from the bottom surface of the electron transfer plate to the first electrode through the hole; Light-emitting device manufacturing method.
The method of claim 9,
In the step (a), a polymer layer is disposed on the first electrode, a block copolymer layer is disposed on the polymer layer,
The step (c) includes forming a plurality of holes in the block copolymer layer by removing a specific material from among the phase-separated materials, and removing a region of the polymer layer exposed by the hole to the first electrode. The method of manufacturing a light emitting device comprising the step of exposing a region corresponding to the position of the hole of the.
The method of claim 9 or 10,
After step (d),
(e) disposing a quantum dot emission layer including quantum dots on the electron transport layer;
The method of claim 9 or 10,
A method of manufacturing a light emitting device in which the specific material is removed by immersing the block copolymer layer in a solvent that selectively removes the specific material.
The method of claim 9,
The block copolymer layer is a method of manufacturing a light emitting device of polystyrene-block-poly(2-vinylpyridine) copolymer (PS-b-P2VP).
The method of claim 13,
The specific material is P2VP (poly(2-vinylpyridine) copolymer) a light emitting device manufacturing method.
The method of claim 10,
The polymer layer is a method of manufacturing a light emitting device of PVA (Polyvinyl Alcohol).
The method of claim 10,
The polymer layer, the block copolymer layer, and the electron transport layer are selected from among a spin-coating method, a dip coating method, a roll-to-roll method, and a doctor blade method. A method of manufacturing a light emitting device disposed using any one.

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