KR102343881B1 - Light emitting device and method of manufacturing light emitting device - Google Patents

Abstract

A light emitting device according to embodiments of the present invention includes a substrate, a first electrode formed on the substrate, a light emitting layer formed on the first electrode to generate light, a second electrode formed on the light emitting layer, and between the light emitting layer and the second electrode and an electron injection layer formed between the first oxide layer and the first oxide layer and the second electrode and having a second oxide layer having a different energy level from the first oxide layer.
Therefore, according to the light emitting device according to the embodiments of the present invention, it is possible to facilitate the movement of electrons from the electrode to the light emitting layer, or to adjust the balance of electrons and holes moving to the light emitting layer. Accordingly, there is an effect that the electrical and optical characteristics of the light emitting device are improved.

Description

A light emitting device and a manufacturing method of a light emitting device

The present invention relates to a light emitting device and a method of manufacturing the light emitting device, and more particularly, to a light emitting device with improved electrical and optical properties and a method of manufacturing the light emitting device.

Organic Light Emitting Device (OLED) and Quantum-Dot Light Emitting Device (QD-LEDs), which are recently spotlighted as next-generation displays, emit light by the existing backlight, and color by the color filter. It is a self-luminous display that can emit light of all natural colors by itself, unlike a liquid crystal display device that realizes Because of these characteristics, organic electroluminescent devices (OLEDs) and quantum dot electroluminescent devices (QLEDs) do not require a separate light source, so they have strengths such as thinness and weight reduction, and natural full color realization.

In such a display device, research to improve electrical and optical properties is being actively conducted.

Korean Patent Laid-Open Patent Publication 10-2009-0059486

The present invention provides a light emitting device having improved electrical and optical properties and a method of manufacturing the light emitting device.

The present invention provides a light emitting device with improved electron injection and movement and a method of manufacturing the light emitting device.

A light emitting device according to an embodiment of the present invention includes: a substrate; a first electrode formed on the substrate; a light emitting layer formed on the first electrode to generate light; a second electrode formed on the light emitting layer; and an electron injection layer having a first oxide layer formed between the light emitting layer and the second electrode and a second oxide layer formed between the first oxide layer and the second electrode, and having a different energy level from the first oxide layer; include

An energy level of the first oxide layer may be greater than an energy level of the second oxide layer.

An energy level of the first oxide layer may be lower than an energy level of the second oxide layer.

The first and second oxide layers may include oxide particles, and the oxide particles may have a particle diameter of 1 nm to 20 nm.

One of the first and second oxide layers includes oxide particles made of ZnO, and the other includes oxide particles in which ZnO is doped with a metal.

The metal doped into the ZnO is Mg or Ca.

In doping the metal into the ZnO, the metal is doped in an amount of 30 wt% or less with respect to the entire oxide particle.

a hole transport layer formed between the first electrode and the light emitting layer; An electron transport layer formed between the emission layer and the electron injection layer may be included.

A method of manufacturing a light emitting device according to an embodiment of the present invention includes a process of sequentially stacking a first electrode, a light emitting layer, an electron injection layer, and a second electrode on a substrate,

The forming of the electron injection layer may include: forming a first oxide layer on the light emitting layer; and laminating and forming a second oxide layer having a different energy level from that of the first oxide layer on the first oxide layer.

In forming the first and second oxide layers, one of the first and second oxide layers is formed to include oxide particles made of ZnO, and the other is formed to include oxide particles in which ZnO is doped with a metal. The metal to be formed and doped into the ZnO is Mg or Ca.

In forming the first and second oxide layers, the oxide particles are formed to have a particle diameter of 1 nm to 20 nm.

In forming the first oxide layer, annealing the underlying layer of the first oxide layer is included.

According to the light emitting device according to embodiments of the present invention, the electron injection layer is formed by stacking the first and second oxide layers having different energy levels. Accordingly, it is possible to facilitate the movement of electrons from the electrode to the light emitting layer, or to control the balance of electrons and holes moving to the light emitting layer. Accordingly, there is an effect that the electrical and optical characteristics of the light emitting device are improved.

1 is a view showing a light emitting device according to embodiments of the present invention.
2 is a conceptual diagram illustrating a balance band (VB), a conduction band (CB), and a band gap (BG) in order to explain the energy level (eV) of the oxide layer according to the experimental examples. It is a drawing shown as
3 is a graph showing absorbance according to wavelength in oxide layers according to Experimental Examples 1 to 3;
4 is a graph obtained by converting FIG. 3 into absorbance according to bandgap energy.
5 is a graph showing the results of measurement of oxide layers according to Experimental Examples 1 to 3 by photoelectron spectroscopy (UPS).
6 is a graph illustrating a balance band region of an oxide layer according to Experimental Examples 1 to 3;
7 is a voltage (V)-current density (mA/cm ² ) graph according to the fourth to sixth experimental examples, and FIG. 8 is a logarithmic scale of FIG. 7 .
9 is a view showing a part of a light emitting device according to the first embodiment of the present invention, and is shown according to an energy level (electron volt; eV).
10 is a diagram illustrating a part of a light emitting device according to a second embodiment of the present invention, and is shown according to an energy level (eV).

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only these embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those of ordinary skill in the art completely It is provided to inform you. The drawings may be exaggerated to describe the embodiments of the present invention, and like reference numerals in the drawings refer to like elements.

The present invention relates to a light emitting device having improved electrical and optical properties and a method for manufacturing the light emitting device. More specifically, the present invention relates to a light emitting device with improved electron injection and movement and a method for manufacturing the light emitting device. Here, the light emitting device may be an organic light-emitting device (OLED) or a quantum-dot light-emitting device (QLED).

1 is a view showing a light emitting device according to embodiments of the present invention.

Hereinafter, a light emitting device according to embodiments of the present invention will be described with reference to FIG. 1 . In this case, an organic light emitting device (OLED) will be described as an example of the light emitting device.

Referring to FIG. 1 , a light emitting device according to embodiments of the present invention includes a substrate 100 , a first electrode 200 formed on the substrate 100 and functioning as an anode, and a first electrode 200 . Electrons formed on the light emitting layer 400 where holes and electrons meet to generate light and are stacked on the light emitting layer 400 and having first and second oxide layers 610 and 620 having different energy levels from each other and a second electrode 700 formed on the injection layer 600 and the electron injection layer 600 and functioning as a cathode.

In addition, the light emitting device may include a hole transport layer 300 formed between the first electrode 200 and the emission layer 400 and an electron transport layer 500 formed between the emission layer 400 and the electron injection layer 600 . . In addition, a hole injection layer (not shown) formed between the first electrode 200 and the hole transport layer 300 may be further included.

The substrate 100 may be glass having a light transmittance property. Of course, the present invention is not limited thereto, and a flexible film may be used for the substrate 100 . The flexible film is one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene (PE), polyethersulfone (PES), polycarbonate (PC), polyarylate (PAR) and polyimide (PI). Either one can be used.

The first electrode 200 is an anode providing a hole, and may be formed of a transparent or translucent conductive material so that light generated in the light emitting layer 400 can be emitted out of the light emitting device. The first electrode 200 is, for example, Indium-Tin-Oxide (ITO), Indium Zinc Oxide (IZO), AZO (ZnO:Al), GZO (ZnO:Ga), BZO (ZnO:B), and SnO2 (SnO2). :F) can be formed in any one of.

The second electrode 700 is a cathode for supplying electrons, has electrical conductivity, and may be formed of a metal material having a predetermined reflectance so that the generated light can be reflected and directed to the first electrode 200 . . For example, the second electrode 700 may be formed of any one of aluminum (Al), silver (Ag), and magnesium (Mg).

In the above, the first electrode 200 has a light-transmitting characteristic and the second electrode 700 is formed to have a high reflectance, so that the light generated in the light emitting layer 400 is emitted through the first electrode 200 . explained. However, the present invention is not limited thereto, and the first electrode 200 may be formed to have a high reflectance and the second electrode 700 to have a light transmission characteristic so that light is emitted through the second electrode 700 . have.

Each of the first and second electrodes 100 and 700 described above is a thermal evaporation method, an electron beam evaporation method, a sputtering deposition method, a plasma enhanced chemical vapor deposition (PECVD) method, and an ALD method. (atomic layer deposition) may be formed by any one method.

The hole transport layer 300 is formed of a material that allows the holes transferred from the first electrode 200 to smoothly move, ie, transport, to the light emitting layer 400 , and may be formed using, for example, an organic material. More specific examples, NPD (or NPB), TPD (N,N'-bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine), s-TAD and MTDATA (4,4', 4"-Tris(N-3-methylphenyl-N-phenyl-amino)-triphenylamine) may be formed of at least one material.

The light emitting layer 400 is a layer that generates light when holes and electrons meet and is excited, and may be formed of, for example, an organic material, and the organic material may be selected according to a color to be generated. That is, the light emitting layer 400 may be formed to emit any one of red, green, blue, and white, and may be formed using a phosphorescent material or a fluorescent material. .

To explain with a more specific example, a host material containing CBP (carbazole biphenyl) or mCP (1,3-bis (carbazol-9-yl)) is doped with a phosphorescent or fluorescent dopant to emit red (Green) light. In this case, the phosphorescent dopant is PIQIr(acac)(bis(1-phenylisoquinoline)acetylacetonate iridium), PQIr(acac)(bis(1-phenylquinoline)acetylacetonate iridium), PQIr(tris(1-phenylquinoline) )iridium) and a material including at least one of octaethylporphyrin platinum (PtOEP) may be used, and a material including PBD:Eu(DBM)3(Phen) and Perylene as a fluorescent dopant may be used.

In addition, a _{dopant may be doped into at least one host material of Alq 3} (hydroxyquinoline aluminum), CBP, and mCP to form a light emitting layer emitting green light. In this case, a material containing, for example, Ir(ppy)3(fac tris(2-phenylpyridine)iridium) may be used as a dopant.

As another example, when it is desired to emit blue light, the light emitting layer may be formed by doping a phosphorescent dopant of at least one of FIrpic and (CF3ppy)2Ir(pic) into a host material including at least one of CBP and mCP. . In addition, the light emitting layer may be formed of a fluorescent material including any one selected from the group consisting of spiro-DPVBi, spiro-6P, distylbenzene (DSB), distrylarylene (DSA), PFO-based polymers and PPV-based polymers. have.

The electron transport layer 500 is a layer that transfers electrons transferred from the electron injection layer 600 to the light emitting layer, for example _{, at least one of Alq 3} (tris(8-hydroxyquinolino)aluminum), PBD, TAZ, spiro-PBD, BAlq, and SAlq. It can be formed from organic materials of

The material for forming each of the hole transport layer 300 , the light emitting layer 400 , and the electron transport layer 500 is not particularly limited to the above-described materials, and various materials capable of performing each function may be used.

In addition, although it has been described above that the hole transport layer 300 , the light emitting layer 400 , and the electron transport layer 500 are formed of an organic material, the present invention is not limited thereto, and may be formed of an inorganic material.

In addition, a material for forming the hole transport layer 300 , the light emitting layer 400 , and the electron transport layer 500 may be a solid material, and may be a thermal evaporation method, an electron beam evaporation method, or sputtering. It may be formed by any one of a deposition method, a plasma enhanced chemical vapor deposition (PECVD) method, and an atomic layer deposition (ALD) method.

In addition, the hole transport layer 300, the light emitting layer 400, and the electron transport layer 500 are not limited to a solid material, and may be formed of a liquid material, in which case spin coating, dip coating, It may be formed by ink-jet coating and spin casting.

The electron injection layer 600 is a layer that injects or transports electrons provided from the second electrode 700 to the electron transport layer 500, and includes first and second oxide layers 610 and 620 having different energy levels. .

Hereinafter, for convenience of description, the oxide layer relatively adjacent to the electron transport layer 500 is referred to as the first oxide layer 610 , and the oxide layer relatively adjacent to the second electrode 700 is referred to as the second oxide layer 620 . ) is called

Each of the first and second oxide layers 610 and 620 is formed as a thin film including a plurality or a plurality of oxide particles. In addition, the oxide particles included in each of the first and second oxide layers 610 and 620 may be ZnO particles or particles in which a metal is doped into the ZnO particles, and the doped metal may be Mg or Ca.

Hereinafter, oxide particles in which Mg is doped into ZnO are expressed as MgZnO, and oxide particles in which ZnO is doped with Ca are expressed as CaZnO.

Reflecting this, and more specifically, one of the first and second oxide layers 610 and 620 is formed to include a plurality of ZnO particles, and the other is formed to include a plurality of MgZnO particles or CaZnO particles. do.

And, when ZnO is doped with any one metal of magnesium (Mg) and calcium (Ca) as a whole (100 wt%), it is formed so that the doped metal is 30 wt% or less (more than 0 wt%). In other words, when a metal doped into ZnO _{is expressed as 'Zn x} Y _1-x O', Y is Mg or Ca, and 1-x may be greater than 0 and less than or equal to 0.3.

In addition, the particle diameter of the oxide particles included in each of the first and second oxide layers 610 and 620 is nanometer (nm), and is formed to be 1 nm to 20 nm, more preferably 3 nm to 8 nm.

Forming the oxide particles included in the first and second oxide layers 610 and 620 to have a size of nanometers (nm) has electrical characteristics, that is, the former This is because mobility is improved.

On the other hand, when the oxide particles are formed to have a particle diameter of more than 20 nm, there is no or insignificant effect of improving the electrical properties by the oxide particles. In addition, there is a problem in that it is difficult to provide a size of the oxide particles less than 1 nm. Accordingly, the oxide particles are formed to have a particle diameter of 1 nm to 20 nm, more preferably 3 nm to 8 nm.

A raw material for forming each of the first and second oxide layers 610 and 620 (hereinafter, a raw material for forming an oxide layer) may be prepared by a sol-gel method. More specifically, when preparing a raw material for forming an oxide layer containing ZnO particles, first, a precursor containing Zn (hereinafter, a first source raw material) is melted in a first solvent, and a precursor containing oxygen ( Hereinafter, the reaction raw material) is melted in the second solvent. As the first source material containing Zn, zinc acetate dihydrate may be used, and DMSO (dimethyl sulfoixde) may be used as the first solvent. In addition, tetramethylammoniumhydroixde (TMAH) may be used as a reaction raw material containing oxygen, and ethanol may be used as a second solvent. Then, the first solvent in which the first source raw material is dissolved and the second solvent in which the reaction raw material is dissolved are mixed, followed by synthesis and precipitation reaction. At this time, the first source raw material and the reaction raw material react to generate a large number of ZnO particles, and the ZnO particles are precipitated. Accordingly, a plurality of ZnO particles are included, and a raw material for forming an oxide layer in a liquid or paste state is provided.

As another example, in preparing a raw material for forming an oxide layer including Mg or Ca doped particles in ZnO, that is, MgZnO particles or CaZnO particles, the first source raw material, the reaction raw material, and the first and second solvent are the above-described materials. can be used in the same way as In addition, a metal precursor is further added, magnesium acetate tetrahydrate may be used as a precursor containing Mg (hereinafter, second source material), and calcium chloride may be used as a precursor containing Ca (hereinafter, second source material). have.

When the raw material for forming the oxide layer is prepared, it is applied on the electron transport layer 500 to form an oxide layer. At this time, it can be applied by spin coating (Coating) or printing (printing) method. In addition, the underlying layer, for example, the electron transport layer 300 may be annealed before application. An oxide layer is formed on the electron transport layer 500 through this process, and the oxide layer includes any one of ZnO oxide particles, MgZnO oxide particles, and CaZnO oxide particles.

2 is a conceptual diagram illustrating a balance band (VB), a conduction band (CB), and a band gap (BG) in order to explain the energy level (eV) of the oxide layer according to the experimental examples. It is a drawing shown as 3 is a graph showing absorbance according to wavelength in oxide layers according to Experimental Examples 1 to 3; 4 is a graph obtained by converting FIG. 3 into absorbance according to bandgap energy.

5 is a graph showing the results of measurement of oxide layers according to Experimental Examples 1 to 3 by photoelectron spectroscopy (UPS). 6 is a graph showing the binding energy (eV) of the balance band region of the oxide layer according to the first to third experimental examples.

Table 1 shows the secondary electron cut-off energy (E _cut-off ) (eV) of the oxide layer according to the first to third experimental examples, the Fermi level (eV), and the onset energy of the balance band region (E _on-set ) (eV) ), the maximum energy of the balance band (E _MX-VB ) (eV), the bandgap energy (E _BG ) (eV), and the minimum energy of the conduction band (E _MM-CB ) (eV) are summarized and shown.

Secondary electron cut-off energy (E _cut-off ) (eV) Fermi level (eV) _On-set energy of the balance band region (E on-set ) (eV) Maximum energy of the balance band (E _MX-VB ) (eV) Bandgap Energy (E _BG ) (eV) Minimum energy of conduction band (E _MM-CB ) (eV) Experiment 1 17.98 3.22 3.78 7.00 3.39 3.61 2nd Experimental Example 17.86 3.34 4.04 7.38 3.67 3.71 3rd Experimental Example 17.85 3.35 4.20 7.55 3.68 3.87

The first experimental example is an oxide layer including ZnO particles, and the second and third experimental examples are oxide layers including MgZnO particles in which ZnO is doped with Mg. The second and third experimental examples have different doped Mg concentrations. The second experimental example is an oxide layer having an Mg doping concentration of 10 wt%, and the third experimental example is an oxide layer having a Mg doping concentration of 15 wt%.

The absorbance of the oxide layer according to the first to third experimental examples is, for example, as shown in FIG. 3, and when converted, it is shown in FIG. 4 .

In converting FIG. 3 to FIG. 4, Equation 1 below was used.

[Formula 1]

where h is the Planck constant, c is the speed of light, and λ is the wavelength. And, E is energy (eV).

4 and Table 1, a first experiment example the band gap energy (E _BG) is 3.39eV, a second experiment example the band gap energy (E _BG) is 3.67eV, the third experiment example the band gap energy (E _BG) is 3.68 eV. _{That is, compared to the bandgap energy (E BG} ) of the oxide layer containing ZnO particles (Experiment 1), the bandgap energy of the oxide layer containing MgZnO particles doped with Mg (Examples 2 and 3) It can be seen that (E _{BG ) is large.}

_{5 and Table 1, secondary electron cut-off} energy (E _cut-off ) (eV) of the oxide layer according to the first to third experimental examples can be seen. That is, in the first experimental example, the secondary electron cut-off energy (E _cut-off ) was 17.98 eV, in the second experimental example, the secondary electron cut-off energy (E _cut-off ) was 17.86 eV, in the third experimental example, the secondary electron cut-off energy (E cut-off ) was 17.98 eV It can be seen that the off energy (E _{cut-off ) is 17.85 eV.}

And, referring to FIGS. 6 and Table 1, the on-set energy E _on-set (eV) of the balance band region of the first to third experimental examples can be seen. That is, the first experimental example is the valence band region of the onset of energy (E _on-set) is 3.78eV, a second experiment example of the valence band region of the onset of energy (E _on-set) is 4.04eV, the third experiment example will balance It can be seen that the _on-set energy E on-set of the band region is 4.20 eV.

_{When the secondary electron cut-off energy E cut-off} detected or derived through FIGS. 5 and 6 and the _on-set energy E on-set of the balance band region are used, the oxide layers according to the first to third experimental examples It is possible to calculate the maximum energy (E _MX-VB ) (eV) of the balance band for . In this case, the maximum energy (E _MX-VB ) (eV) of the balance band may be calculated using Equation 2 below.

[Equation 2]

In Equation 2, E _MX-VB is the maximum energy of the balance band, E _I is the energy of an incident photon, and may be 21.2 eV _{, E cut-off} is the secondary electron cut-off energy, E _on-set is the onset of the balance band region is energy.

When the energy (E _I ) of the incident photon, the secondary electron cut-off energy (E _{cut-off ), and the on-set} energy of the balance band region (E on-set ) are applied to Equation 2, the maximum energy of the balance band (E _{MX -VB} ) is calculated. That is, the maximum energy (E _MX-VB ) of the balance band of the first experimental example is 7.00 eV, the maximum energy (E _MX-VB ) of the balance band of the second experimental example is 7.38 eV, the maximum energy of the balance band of the third experimental example ( E _MX-VB ) is 7.55 eV.

And, calculating the difference between the maximum energy of the balance band (E _MX-VB ) and the bandgap energy (E _BG ) (eV), the minimum energy of the conduction band (E _MM-CB ) (eV) is calculated (Equation see 3).

[Equation 3]

That is, the minimum energy (E _MM-CB ) of the conduction band of the first experimental example is 3.61 eV, the minimum energy (E _MM-CB ) of the conduction band of the second experimental example is 3.71 eV, and that of the conduction band of the third embodiment The minimum energy (E _MM-CB ) is 3.87 eV.

_{From this, it can be seen that the minimum energy (E MM-CB} ) of the conduction bands of the first to third experimental examples are different from each other. _{In addition, compared to the minimum energy (E MM-CB} ) of the conduction band of the oxide layer containing ZnO particles (Experiment 1), the oxide layer containing MgZnO particles doped with Mg (Examples 2 and 3) ), it can be seen that the minimum energy (E _{MM-CB ) of the conduction band is large.} And, comparing the second and third experimental examples, it can be seen that _{the minimum energy (E MM-CB ) of the conduction band is different according to the doping concentration of Mg.}

In this way, the minimum energy (E _MM-CB ) (eV) of the conduction band having different values may be explained as having different energy levels. Therefore, the energy level of the oxide layer (Example 2 and 3) containing MgZnO particles doped with metal such as Mg is higher than the energy level of the oxide layer containing ZnO particles (Example 1). can

7 is a voltage (V)-current density (mA/cm ² ) graph according to the fourth to sixth experimental examples, and FIG. 8 is a logarithmic scale of FIG. 7 . In Experimental Examples 4 to 6, different oxide layers were formed between the first electrode and the second electrode. Here, the first electrode of Experimental Examples 4 to 6 was formed of ITO (Indium-Tin-Oxide), and the second electrode was formed of aluminum (Al) in the same manner. And, the oxide layer according to Experimental Example 4 is an oxide layer including ZnO particles, and Experimental Examples 5 and 6 are oxide layers including MgZnO particles in which ZnO is doped with Mg. Experimental Examples 5 and 6 have different doped Mg concentrations. Experimental Example 4 is an oxide layer having a Mg doping concentration of 10 wt%, and Experimental Example 6 is an oxide layer having a Mg doping concentration of 15 wt%.

7 and 8 , it can be seen ^{that the current density (mA/cm 2} ) characteristics according to the voltage (V) of the fourth to sixth experimental examples are different. That is, it can be seen ^{that the current density (mA/cm 2} ) characteristics according to the voltage (V) are different depending on the type of oxide particles (ie, ZnO particles or MgZnO particles) included in the oxide layer and the doping concentration of the metal.

9 is a view showing a part of a light emitting device according to the first embodiment of the present invention, and is shown according to an energy level (electron volt; eV). 10 is a diagram illustrating a part of a light emitting device according to a second embodiment of the present invention, and is shown according to an energy level (eV).

In embodiments of the present invention, the electron injection layer 600 is formed by laminating the first and second oxide layers 610 and 620 including the oxide particles as described above. In this case, the energy levels of the first oxide layer 610 and the second oxide layer 620 are different from each other.

More specifically, as in the first embodiment shown in FIG. 9 , the energy level of the second oxide layer 620 may be lower than that of the first oxide layer 610 . For this, for example, the first oxide layer 610 may be formed to include MgZnO particles or CaZnO particles by doping ZnO with Mg or Ca, and the second oxide layer 620 may be formed to include ZnO particles. Accordingly, the energy level of the second oxide layer 620 is lower than that of the first oxide layer 610 .

In this way, when the energy level of the second oxide layer 620 adjacent to the second electrode 700 is formed to be lower than that of the first oxide layer 610, the second electrode 700, which is a negative electrode, and The energy barrier between the second oxide layers 620 is lowered. Accordingly, there is an effect that the electron injection and movement speed from the second electrode 700 to the light emitting layer 400 is improved.

As another example, as in the second embodiment shown in FIG. 10 , the energy level of the second oxide layer 620 may be higher than that of the first oxide layer 610 . To this end, for example, the first oxide layer 610 may be formed to include ZnO particles, and the second oxide layer 620 may be formed to include MgZnO particles or CaZnO particles by doping ZnO with Mg or Ca.

In this way, the energy level of the second oxide layer 620 adjacent to the second electrode 700 is formed to be higher than that of the first oxide layer 610 in order to improve the efficiency in which electrons and holes meet in the light emitting layer 400 . can be That is, the charge balance of the speed at which holes provided from the first electrode 100 move to the light emitting layer 400 and the speed at which electrons provided from the second electrode 700 move to the light emitting layer 400 are controlled. It may be to do

In the above, it has been described that the electron injection layer of the organic electroluminescent device is formed of the first and second oxide layers according to the embodiments. However, the present invention is not limited thereto, and the electron injection layer of the quantum dot electroluminescent device may be formed by applying the first and second oxide layers according to the embodiments.

As such, in embodiments of the present invention, by forming the electron injection layer 600 by forming the first and second oxide layers 610 and 620 having different energy levels from each other, the electron transport layer ( 500 ), or the balance of electrons and holes moving to the light emitting layer 400 may be adjusted. Accordingly, electrical and optical properties of the light emitting device, more specifically, at least one of current density, luminance, and quantum efficiency is improved.

100: substrate 200: first electrode
300: hole transport layer 400: light emitting layer
500: electron transport layer 600: electron injection layer
610: first oxide layer 620: second oxide layer
700: second electrode

Claims (12)

Board;
a first electrode formed on the substrate;
a light emitting layer formed on the first electrode to generate light;
a second electrode formed on the light emitting layer; and
an electron injection layer having a first oxide layer formed between the light emitting layer and the second electrode and a second oxide layer formed between the first oxide layer and the second electrode, the second oxide layer having a different energy level from the first oxide layer;
includes,
The first and second oxide layers include oxide particles,
One of the first and second oxide layers includes oxide particles made of ZnO, and the other includes oxide particles in which ZnO is doped with a metal. The method according to claim 1,
The energy level of the first oxide layer is greater than the energy level of the second oxide layer. The method according to claim 1,
The energy level of the first oxide layer is lower than the energy level of the second oxide layer. The method according to claim 1,
The oxide particles have a particle diameter of 1 nm to 20 nm. delete 5. The method according to claim 4,
The metal doped into the ZnO is Mg or Ca. 5. The method according to claim 4,
In doping the metal into the ZnO, a light emitting device doped such that the metal is 30 wt% or less with respect to the entire oxide particle. 8. The method according to any one of claims 1 to 4, 6 and 7,
a hole transport layer formed between the first electrode and the light emitting layer;
and an electron transport layer formed between the light emitting layer and the electron injection layer. A first electrode, a light emitting layer, an electron injection layer and a second electrode are sequentially laminated on a substrate,
The process of forming the electron injection layer,
forming a first oxide layer on the light emitting layer; and
laminating and forming a second oxide layer having a different energy level from that of the first oxide layer on the first oxide layer;
includes,
In forming the first and second oxide layers,
One of the first and second oxide layers is formed to include oxide particles made of ZnO, and the other is formed to include oxide particles doped with metal in ZnO. 10. The method of claim 9,
The metal doped into the ZnO is Mg or Ca, a method of manufacturing a light emitting device. 11. The method of claim 10,
In forming the first and second oxide layers, the method of manufacturing a light emitting device in which the oxide particles are formed to have a particle diameter of 1 nm to 20 nm. 10. The method of claim 9,
and annealing an underlayer of the first oxide layer in forming the first oxide layer.

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