KR102517276B1 - Light emitting diode and light emitting device having the diode - Google Patents

Abstract

The light emitting diode of the present invention includes a charge control layer positioned between the charge transfer layer and any one electrode and including a first material having conductivity and a second material having a wide energy band gap. Due to the charge control layer, static electricity that may be generated inside the light emitting diode can be prevented, and the flow of charges can be controlled so that charges can be injected into the light emitting material layer in a balanced manner.

Description

Light emitting diode and light emitting device including the same {LIGHT EMITTING DIODE AND LIGHT EMITTING DEVICE HAVING THE DIODE}

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode having improved charge transfer characteristics and light extraction efficiency, and a light emitting device including the same.

BACKGROUND ART As electronic engineering technology and information communication technology are rapidly improved, technologies in various fields including a display field for processing and displaying a large amount of data are also rapidly developing. Accordingly, various flat panel display devices are being developed to replace the conventional cathode ray tube (CRT). Among flat panel display devices, an organic light emitting diode (OLED) display device is used as a next-generation display device that can replace a liquid crystal display device (LCD) because of its thin structure and low power consumption.

When the current density of the light emitting diode is increased or the driving voltage is increased to increase the light emitting luminance in the organic light emitting diode display device, the organic light emitting diode's life is shortened due to deterioration due to thermal decomposition of the organic material used in the organic light emitting diode. there is In addition, OLED meets the high level of color gamut required by ITU-R Recommendation BT.2020 (Rec.2020 or BT.2020) in relation to 4K/UHD standards from the International Telecommunication Union (ITU). It is difficult to implement.

Recently, efforts have been made to use inorganic light-emitting particles such as quantum dots (QDs) in display devices. Quantum dots are inorganic light-emitting particles that emit light while electrons in an unstable state descend from a conduction band to a valence band. Quantum dots generate strong fluorescence because they have a very high extinction coefficient and excellent quantum yield among inorganic particles. In addition, since the emission wavelength is changed according to the size of the quantum dots, by adjusting the size of the quantum dots, light in the entire visible light range can be obtained, so that various colors can be implemented.

That is, when quantum dots are used as the light emitting material layer (EML), the color purity of individual pixels can be increased, and white light composed of red (R), blue (B), and green (G) emission of high purity can be realized. Rec. 2020 standards are achievable. Accordingly, a quantum dot light emitting diode (QLED) using quantum dots as a light emitting material is attracting attention.

Defects occur at interfaces between light emitting layers constituting conventional organic light emitting diodes and quantum dot light emitting diodes or on the surface of the light emitting layer, which acts as a limitation in realizing a desired level of light emitting efficiency. In addition, due to the difference in relative mobility between holes and electrons, charge un-balancing occurs, resulting in a decrease in luminous efficiency.

An object of the present invention is to provide a light emitting diode and a light emitting device capable of preventing generation of static electricity caused by charging of electric charges.

Another object of the present invention is to provide a light emitting diode and a light emitting device in which electric charges can be injected into a light emitting material layer in a balanced manner.

Another object of the present invention is to provide a light emitting diode and a light emitting device having improved surface morphology characteristics.

According to one aspect, the present invention provides a first electrode and a second electrode facing each other; a light emitting material layer positioned between the first electrode and the second electrode; and a charge control layer disposed between the light emitting material layer and the first electrode or the second electrode, wherein the charge control layer includes a first material that is a conductive polymer, a cured siloxane, and a (meth)acrylate-based material. Provided is a light emitting diode including a second material selected from the group consisting of polymers, vinyl alcohol-based polymers, and combinations thereof.

For example, the conductive polymer is polyphenylene, polyphenylenevinylene, polyphenylene sulfide, poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, polythiophene, polyacetylene and It may be selected from the group consisting of combinations thereof.

Meanwhile, the cured siloxane may be synthesized from a silane monomer represented by Formula 1 below.

[Formula 1]

In Formula 1, R ₁ and R ₂ are each independently hydrogen, deuterium, tritium, a hydroxy group, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₂ ~ C ₁₀ alkenyl group, C ₁ ~ C ₁₀ alkoxy group , C ₁ ~ C ₁₀ alkyl amino group, C ₁ ~ C ₁₀ alkyl acryloxy group, C ₁ ~ C ₁₀ alkyl methacryloxy group, thiol group, C ₁ ~ C ₁₀ alkyl thiol group, epoxy group, C ₁ ~ C ₁₀ alkyl Epoxy group, C ₅ ~ C ₂₀ cycloalkyl epoxy group, C ₄ ~ C ₂₀ heteroaryl epoxy group, glycidyloxy group, C ₁ ~ C ₁₀ alkyl glycidyloxy group, unsubstituted or halogen atom-substituted C ₅ ~ C ₂₀ aryl group , C ₄ ~ C ₂₀ heteroaryl group, C ₅ ~ C ₂₀ aryloxy group, C ₄ ~ C ₂₀ heteroaryloxy group, C ₅ ~ C ₂₀ aryl amino group and C ₅ ~ C ₂₀ hetero group, unsubstituted or substituted with a halogen atom selected from the group consisting of aryl amino groups; R ₃ and R ₄ are each independently hydrogen, deuterium, tritium, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₁ ~ C ₁₀ alkyl amino group, unsubstituted or halogen atom-substituted C ₅ ~ C ₂₀ aryl group, Selected from the group consisting of an unsubstituted or halogen atom-substituted C ₅ ~C ₂₀ heteroaryl group, a C ₅ ~C ₂₀ aryl amino group, and a C ₅ ~C ₂₀ heteroaryl amino group.

For example, the cured siloxane may be synthesized from a silane monomer in which at least three C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms.

For example, the cured siloxane may be synthesized from a silane monomer in which four C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms.

In an exemplary embodiment, the charge control layer may be formed to a thickness of 1 to 10 nm.

For example, the second material may be a cured siloxane, and in the charge control layer, the first material and the cured siloxane may be mixed in a volume ratio of 3:10 to 1:2.

The sheet resistance of the charge control layer may be greater than or equal to 1 MΩ/sq and less than or equal to 10 MΩ/sq.

The charge control layer may be positioned between an electrode functioning as a cathode among the first electrode and the second electrode.

The light emitting diode may further include an electron transfer layer positioned between the light emitting material layer and the charge control layer, or positioned between the charge control layer and the cathode.

In addition, the light emitting diode may further include a hole transfer layer positioned on the opposite side of the electron transfer layer with the light emitting material layer as a center.

The electron transport layer may include an electron transport layer made of an inorganic material.

For example, the energy band gap between the highest occupied molecular orbital energy level (HOMO _CCL ) and the lowest unoccupied molecular orbital energy level (LUMO _CCL ) of the charge control layer (Eg _CCL ) is the valence band energy of the electron transport layer. It may be greater than the energy band gap (Eg _ETL ) between the level (VB _ETL ) and the conduction band energy level (CB _ETL ).

The highest occupied molecular orbital energy level (HOMO _CCL ) of the charge control layer may be lower than the valence band energy level (VB _ETL ) of the electron transport layer (deep).

In addition, the lowest unoccupied molecular orbital energy level (LUMO _CCL ) of the charge control layer may be higher than the conduction band energy level (CB _ETL ) of the electron transport layer (shallow).

In another aspect, the present invention provides a substrate; And it provides a light emitting device comprising the above-described light emitting diode positioned on the substrate.

In the light emitting diode of the present invention, a charge control layer in which a first material, which is a conductive polymer, and a second material having a wide energy band gap are mixed is formed above or below the charge transfer layer, which may be an electron transfer layer.

It is possible to prevent electrons or electron excitons from being trapped in the electron transfer layer due to defects inside the charge transfer layer, and preventing charging from occurring in an adjacent light emitting material layer. In addition, holes and electrons can be injected into the light emitting material layer in a balanced manner by controlling the injection speed of electrons using a charge control layer containing a material having a wide energy bandgap.

In addition, surface morphology such as flatness of a thin film of a light emitting diode may be improved by forming a charge control layer.

By introducing the charge control layer according to the present invention, it is possible to manufacture and implement a light emitting diode having improved light emitting efficiency and an extended lifespan, and a light emitting device using the same.

1 is a schematic cross-sectional view of a light emitting diode display device as an example of a light emitting device including a light emitting diode according to an exemplary embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view of a light emitting diode according to a first exemplary embodiment of the present invention, showing the light emitting diode having a normal structure.
3 is a diagram schematically illustrating bandgap energies of materials constituting an electrode and a light emitting unit constituting a conventional light emitting diode without forming a charge control layer.
4 schematically shows the bandgap energy of electrodes constituting a light emitting diode and materials constituting a light emitting unit when a charge control layer is formed between the electron transport layer and the second electrode according to the first exemplary embodiment of the present invention. This is the diagram shown.
5 is a schematic cross-sectional view of a light emitting diode according to a second exemplary embodiment of the present invention, showing the light emitting diode having a normal structure.
6 is a schematic cross-sectional view of a light emitting diode according to a third exemplary embodiment of the present invention, showing the light emitting diode having an inverted structure.
FIG. 7 schematically shows bandgap energies of electrodes constituting a light emitting diode and materials constituting a light emitting unit when a charge control layer is formed between the electron transport layer and the first electrode according to the third exemplary embodiment of the present invention. This is the diagram shown.
8 is a schematic cross-sectional view of a light emitting diode according to a fourth exemplary embodiment of the present invention, showing the light emitting diode having an inverted structure.
9 is a graph showing the results of measuring photoluminescence (PL) intensity of a single electron device manufactured according to an exemplary embodiment of the present invention.
10 is a graph measuring emission intensity over time of a single electronic device manufactured according to an exemplary embodiment of the present invention.
11 is a graph showing the results of measuring sheet resistance according to the relative volume ratio of PEDOT:PSS to TEOS constituting the charge control layer according to an exemplary embodiment of the present invention.
12 is a graph showing the results of measuring photoluminescence (PL) intensity of a single electronic device manufactured according to an exemplary embodiment of the present invention.
13 is a graph measuring emission intensity over time of a single electronic device manufactured according to an exemplary embodiment of the present invention.
14 is a photograph of a surface morphology of a device composed of only a quantum dot (QD) light emitting material layer according to a comparative example, using an atomic force microscope (AFM).
15 is a photograph taken using AFM of the surface morphology of an electron-only device composed of only a quantum dot light emitting material layer and an electron transport layer according to a comparative example.
16 is a photograph of the surface morphology of an electron-only device having a quantum dot light emitting material layer, an electron transport layer, and a charge control layer, taken using AFM, according to an exemplary embodiment of the present invention.
17 is a graph showing the results of measuring the light emitting life time of light emitting diodes manufactured according to an exemplary embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings when necessary.

The light emitting diode according to the present invention includes a charge control layer in which a polysiloxane-based material is chemically bonded to the surface of the charge transfer layer, thereby solving the problems of the prior art. The light emitting diode of the present invention can be applied to a lighting device or a display device. FIG. 1 is a schematic cross-sectional view of a light emitting diode display device as an example of a light emitting device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, the light emitting diode display device 100 includes a thin film transistor Tr, a planarization layer 160 covering the thin film transistor Tr, and a thin film transistor Tr disposed on the planarization layer 160. ) and a light emitting diode 200 connected to. The thin film transistor Tr includes a semiconductor layer 110 , a gate electrode 130 , a source electrode 152 , and a drain electrode 154 .

The substrate 102 may be a glass substrate, a thin flexible substrate, or a polymeric plastic substrate. For example, flexible substrates include polyimide (PI), polyethersulfone (PES), polyethylenenaphthalate (PEN), polyethylene terephthalate (PET) and polycarbonate (PC). It can be formed by any one of them. The substrate 102 on which the thin film transistor Tr and the light emitting diode 200 are positioned forms an array substrate.

A buffer layer 104 is formed on the substrate 102 , and a thin film transistor Tr is formed on the buffer layer 104 . The buffer layer 104 may be omitted.

A semiconductor layer 110 is formed on the buffer layer 104 . For example, the semiconductor layer 110 may be made of an oxide semiconductor material. When the semiconductor layer 110 is made of an oxide semiconductor material, a light blocking pattern (not shown) may be formed under the semiconductor layer 110 . The light-shielding pattern prevents light from being incident on the semiconductor layer 110, thereby preventing the semiconductor layer 110 from being deteriorated by light. Alternatively, the semiconductor layer 110 may be made of polycrystalline silicon, and in this case, both edges of the semiconductor layer 110 may be doped with impurities.

A gate insulating film 120 made of an insulating material is formed on the entire surface of the substrate 102 on the semiconductor layer 110 . The gate insulating layer 120 may be made of an inorganic insulating material such as silicon oxide (SiO _x ) or silicon nitride (SiN _x ).

A gate electrode 130 made of a conductive material such as metal is formed on the gate insulating film 120 corresponding to the center of the semiconductor layer 110 . In FIG. 1 , the gate insulating film 120 is formed on the entire surface of the substrate 102 , but the gate insulating film 120 may be patterned in the same shape as the gate electrode 130 .

An interlayer insulating film 140 made of an insulating material is formed on the entire surface of the substrate 102 above the gate electrode 130 . The interlayer insulating film 140 may be formed of an inorganic insulating material such as silicon oxide (SiO _x ) or silicon nitride (SiNx), or an organic insulating material such as benzocyclobutene or photo-acryl. there is.

The interlayer insulating film 140 has first and second semiconductor layer contact holes 142 and 144 exposing top surfaces of both sides of the semiconductor layer 110 . The first and second semiconductor layer contact holes 142 and 144 are spaced apart from the gate electrode 130 on both sides of the gate electrode 130 . In FIG. 1 , the first and second semiconductor layer contact holes 142 and 144 are also shown to be formed in the gate insulating layer 120 . In contrast, when the gate insulating film 120 is patterned in the same shape as the gate electrode 130 , the first and second semiconductor layer contact holes 142 and 144 are formed only within the interlayer insulating film 140 .

A source electrode 152 and a drain electrode 154 made of a conductive material such as metal are formed on the interlayer insulating film 140 . The source electrode 152 and the drain electrode 154 are spaced apart from each other with respect to the gate electrode 130, and are connected to both sides of the semiconductor layer 110 through the first and second semiconductor layer contact holes 142 and 144, respectively. make contact

The semiconductor layer 110, the gate electrode 130, the source electrode 152, and the drain electrode 154 form a thin film transistor Tr, and the thin film transistor Tr functions as a driving element. The thin film transistor Tr illustrated in FIG. 1 has a coplanar structure in which a gate electrode 130 , a source electrode 152 , and a drain electrode 154 are positioned on a semiconductor layer 110 . Alternatively, the thin film transistor Tr may have an inverted staggered structure in which a gate electrode is positioned below the semiconductor layer and a source electrode and a drain electrode are positioned above the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Although not shown in FIG. 1, a gate line and a data line cross each other to define a pixel area, and a switching element connected to the gate line and the data line is further formed. The switching element is connected to the thin film transistor Tr, which is a driving element. In addition, a power line is formed parallel to and spaced apart from the data line or data line, and a storage capacitor is further configured to maintain a constant voltage of the gate electrode of the thin film transistor Tr, which is a driving element, during one frame. can

Meanwhile, the light emitting diode display device 100 may include a color filter (not shown) that absorbs light generated by the light emitting diode 200 . For example, a color filter (not shown) may absorb red (R), green (G), blue (B), and white (W) light. In this case, red, green, and blue color filter patterns that absorb light may be separately formed for each pixel area, and each of these color filter patterns is a light emitting diode 200 that emits light of a wavelength band to be absorbed. ) may be disposed to overlap each other with the light emitting unit 230 in the light emitting unit 230 . By adopting a color filter (not shown), the LED display 100 can implement full-color.

For example, when the light emitting diode display 100 is a bottom emission type, a color filter (not shown) absorbing light may be positioned above the interlayer insulating film 140 corresponding to the light emitting diode 100 . In another exemplary embodiment, when the light emitting diode display device 100 is a top emission type, a color filter (not shown) may be positioned above the light emitting diode 200, that is, above the second electrode 220. .

A planarization layer 160 is formed on the entire surface of the substrate 102 on the source electrode 152 and the drain electrode 154 . The planarization layer 160 has a flat upper surface and has a drain contact hole 162 exposing the drain electrode 154 of the thin film transistor Tr. Here, the drain contact hole 162 is illustrated as being formed right above the second semiconductor layer contact hole 144, but may be formed spaced apart from the second semiconductor layer contact hole 144.

The light emitting diode 200 is located on the planarization layer 160, and the first electrode 210 connected to the drain electrode 154 of the thin film transistor Tr and sequentially located on the first electrode 210 It may include a light emitting unit 230 and a second electrode 220 .

The first electrode 210 is formed separately for each pixel area. As will be discussed later, the first electrode 210 may be an anode or a cathode, and may be made of a conductive material having a relatively high work function value. For example, the first electrode 210 is doped with ITO, IZO, ITZO, ICO, SnO ₂ , In ₂ O ₃ , Cd:ZnO, F:SnO ₂ , In:SnO ₂ , Ga:SnO ₂ and AZO. or undoped metal oxides. If necessary, the first electrode 210 may include nickel (Ni), platinum (Pt), gold (Au), silver (Ag), iridium (Ir), or carbon nanotubes in addition to the aforementioned metal oxide.

Meanwhile, when the LED display device 100 of the present invention is a top-emission type, a reflective electrode or a reflective layer may be further formed below the first electrode 210 . For example, the reflective electrode or the reflective layer may be made of an aluminum-palladium-copper (APC) alloy.

In addition, a bank layer 170 covering an edge of the first electrode 210 is formed on the planarization layer 160 . The bank layer 170 exposes the center of the first electrode 210 corresponding to the pixel area.

A light emitting unit (light emitting layer) 230 is formed on the first electrode 210 . In one exemplary embodiment, the light emitting unit 230 may include a light emitting material layer, a charge transfer layer, and a charge control layer. For example, the light emitting unit 230, as shown in FIGS. 2, 5, 6, and 7, the first charge transfer layer 340, 440, 540, 640, the light emitting material layer 350, 450, 550, 650), second charge transfer layers 360, 460, 560, and 660, and/or charge control layers 370, 470, 570, and 670. Structures and positional relationships of the light emitting material layer, the charge transfer layer, and the charge control layer constituting the light emitting unit 230 will be described later.

A second electrode 220 is formed on the substrate 102 on which the light emitting unit 230 is formed. The second electrode 220 is positioned on the front surface of the display area and may be made of a conductive material having a relatively low work function value, and may be a cathode or an anode. For example, the second electrode 420 may be Ca, Ba, Ca/Al, LiF/Ca, LiF/Al, BaF ₂ /Al, CsF/Al, CaCO ₃ /Al, BaF ₂ /Ca/Al, Al, It may consist of Mg, Au:Mg or Ag:Mg.

An encapsulation film 180 is formed on the second electrode 220 to prevent penetration of external moisture into the light emitting diode 200 . The encapsulation film 180 may have a stacked structure of a first inorganic insulating layer 182 , an organic insulating layer 184 , and a second inorganic insulating layer 186 , but is not limited thereto.

Next, a light emitting diode according to the present invention will be described. 2 is a schematic cross-sectional view of a light emitting diode according to an exemplary embodiment of the present invention. As shown in FIG. 2, a light emitting diode 300 according to an exemplary embodiment of the present invention includes a first electrode 310, a second electrode 320 facing the first electrode 310, and a first It is positioned between the electrode 310 and the second electrode 320 and includes a light emitting layer 330 including an emitting material layer (EML, 350).

The light emitting layer 330, which is a light emitting unit, includes a first charge transfer layer (CTL1, 340) positioned between the first electrode 310 and the light emitting material layer 350, and the light emitting material layer 350. A second charge transfer layer (CTL2, 360) positioned between the two electrodes 320 may be further included. Meanwhile, according to the present embodiment, the light emitting layer 330 includes a charge control layer (CCL, 370) positioned between the second electrode 320 and the second charge transfer layer 360 which may be made of an inorganic material. may include more.

The first electrode 310 may be an anode such as a hole injection electrode. The first electrode 310 may be formed on a substrate (see FIG. 1) that may include glass or a polymer material. For example, the first electrode 310 may be indium-tin-oxide (ITO), indium-zinc-oxide (IZO), or indium-tin-zinc-oxide (indium-tin-oxide). tin-zinc oxide (ITZO), indium-copper-oxide (ICO), tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), cadmium:zinc oxide (Cd:ZnO), fluorine Doped or undoped, including: tin oxide (F:SnO ₂ ), indium:tin oxide (In:SnO ₂ ), gallium:tin oxide (Ga:SnO ₂ ) and aluminum:zinc oxide (Al:ZnO; AZO). may contain metal oxides. Optionally, the first electrode 310 may include nickel (Ni), platinum (Pt), gold (Au), silver (Ag), iridium (Ir), or carbon nanotube (CNT) in addition to the aforementioned metal oxide. may include more.

In this embodiment, the second electrode 320 may be a cathode such as an electron injection electrode. For example, the second electrode 320 may be Ca, Ba, Ca/Al, LiF/Ca, LiF/Al, BaF ₂ /Al, CsF/Al, CaCO ₃ /Al, BaF ₂ /Ca/Al, Al, Mg, It may consist of Au:Mg or Ag:Mg. For example, the first electrode 310 and the second electrode 320 may each have a thickness of 5 to 300 nm, preferably 10 to 200 nm, but the present invention is not limited thereto.

In one exemplary embodiment, in the case of a bottom emission type light emitting diode, the first electrode 310 may be made of a transparent conductive metal such as ITO, IZO, ITZO, or AZO, and the second electrode 320 may be Ca , Ba, Ca/Al, LiF/Ca, LiF/Al, BaF ₂ /Al, Al, Mg, Ag:Mg alloy, etc. may be used.

The first charge transfer layer 340 is positioned between the first electrode 310 and the light emitting material layer 350 . The first charge transfer layer 340 may be a hole transfer layer supplying holes to the light emitting material layer 350 . For example, the first charge transfer layer 340 is a hole injection layer (HIL, 342) positioned adjacent to the first electrode 310 between the first electrode 310 and the light emitting material layer 350. and a hole transport layer (HTL, 344) positioned adjacent to the light emitting material layer 350 between the first electrode 310 and the light emitting material layer 350.

The hole injection layer 342 facilitates hole injection from the first electrode 310 into the light emitting material layer 350 . In one example, the hole injection layer 342 may include poly(ethylenedioxythiophene):polystyrenesulfonate (poly(ethylenedioxythiophene):polystyrenesulfonate; PEDOT:PSS); 4,4',4"-tris(diphenylamino)triphenylamine (4,4',4" doped with tetrafluoro-tetracyano-quinodimethane (F4-TCNQ)) -tris(diphenylamino)triphenylamine; TDATA); p-doped phthalocyanines such as, for example, F4-TCNQ doped zinc phthalocyanine (ZnPc); F4-TCNQ doped N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine (N,N'-diphenyl-N ,N'-bis(1-naphtyl)-1,1'-biphenyl-4,4"-diamine; α-NPD); It may be made of an organic material selected from the group consisting of hexaazatriphenylene-hexanitrile (HAT-CN) and combinations thereof, but the present invention is not limited thereto. For example, a dopant such as F4-TCNQ may be doped in an amount of 1 to 30% by weight with respect to the host. The hole injection layer 342 may be omitted depending on the structure and shape of the light emitting diode 300 .

The hole transport layer 344 transfers holes from the first electrode 310 to the light emitting material layer 350 . The hole transport layer 344 may be made of an inorganic or organic material.

For example, when the hole transport layer 344 is made of an organic material, the hole transport layer 344 is 4,4'-bis (N-carbazolyl) -1,1'-biphenyl (4,4'-Bis (N- 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds such as carbazolyl)-1,1'-biphenyl; CBP, CBDP) (4,4'-bis(p-carbazolyl) -1,1'-biphenyl compounds); N,N'-di(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (N,N'-Di(1-naphthyl)- N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine; NPB, NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1 ,1'-biphenyl)-4,4'-diamine (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine; TPD), N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) -spiro (N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) - spiro; spiro-TPD), N,N'-di(4-(N,N'-diphenyl-amino)phenyl-N,N'-diphenylbenzidine (N,N'-di(4-(N, N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine; DNTPD), 4,4',4"-tris(N-carbazolyl-triphenylamine(4,4',4"-tris(N -carbazolyl)-triphenylamine; TCTA), tetra-N-phenylbenzidine (TPB), tris(3-methylphenylphenylamino)-triphenylamine (tris(3-methylphenylphenylamino)-triphenylamine; m-MTDATA ), poly (9,9'-dioctylfluorenyl-2,7-diyl) -co- (4,4'- (N- (4-sec-butylphenyl) diphenylamine (poly (9,9 '-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine; TFB), poly(4-butylphenyl-diphenylamine) Aryl, an aromatic amine or polynuclear aromatic amine selected from the group consisting of butylphenyl-dipnehyl amine); poly-TPD), spiro-NPB, and combinations thereof Amines: polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate; conductive polymers such as PEDOT:PSS); Poly(N-vinylcarbazole); PVK) and its derivatives, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (p oly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]; MEH-PPV) or poly[2-methoxy-5-(3',7'-dimethyloctyloxy)1,4- phenylenevinylene] (poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]; poly(para)phenylenevinylene ( poly(para) phenylenevinylene) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spiro-fluorene) -fluorene)) and its derivatives; metal complex compounds such as copper phthalocyanine (CuPc); And it may be made of an organic material selected from the group consisting of combinations thereof.

When the hole transport layer 344 is made of an inorganic material, the hole transport layer 344 is a metal oxide such as NiO, MoO ₃ , Cr ₂ O ₃ , Bi ₂ O ₃ or p-type ZnO, copper thiocyanate (CuSCN), Mo ₂ It may be made of an inorganic material selected from the group consisting of non-oxide metal materials such as S and p-type GaN and/or combinations thereof.

In FIG. 2 , the first charge transfer layer 340, which may be a hole transfer layer, is divided into a hole injection layer 342 and a hole transport layer 344. Alternatively, the first charge transfer layer 440 may be formed of a single layer. For example, the first charge transfer layer 340 may be formed of only the hole transport layer 344 without the hole injection layer 342, and a hole injection material (for example, PEDOT:PSS) is doped with the hole transport organic material described above. may be done.

The first charge transfer layer 340 including the hole injection layer 342 and the hole transport layer 344 may be formed by a vacuum deposition process such as a vacuum vapor deposition method or a sputtering method, spin coating, drop coating, A solution process such as dip coating, spray coating, roll coating, flow coating, casting process, screen printing or inkjet printing may be formed alone or in combination. . For example, the hole injection layer 342 and the hole transport layer 344 may each have a thickness of 10 nm to 200 nm, preferably 10 nm to 100 nm, but the present invention is not limited thereto.

The light emitting material layer 350 may be formed of inorganic light emitting particles or organic light emitting materials. When the light emitting material layer 350 is formed of inorganic light emitting particles, the inorganic light emitting particles may be formed of nano inorganic light emitting particles such as quantum dots (QDs) or quantum rods (QRs). Quantum dots or quantum rods are inorganic particles that emit light as electrons in an unstable state descend from a conduction band energy level to a valence band energy level.

These nano-inorganic light-emitting particles have a very high extinction coefficient and excellent quantum yield among inorganic particles, so they generate strong fluorescence. In addition, since the emission wavelength is changed according to the size of the nano-inorganic light-emitting particles, adjusting the size of the nano-inorganic light-emitting particles can obtain light in the entire range of visible light, so that various colors can be implemented. That is, when nano-inorganic light-emitting particles such as quantum dots or quantum rods are used as the light-emitting material of the light-emitting material layer 350, the color purity of individual pixels can be increased, and thus high-purity red (R), green (G), and blue light-emitting particles can be used. (B) It is possible to implement white light composed of light emission.

In one exemplary embodiment, quantum dots or quantum rods may have a unitary structure. In another exemplary embodiment, quantum dots or quantum rods may have a core/shell heterogeneous structure. At this time, the shell may be composed of one shell or may be composed of multiple shells.

Depending on the reactivity of the reactive precursor that can be synthesized into the core and/or the shell, the injection rate of the reactive precursor for synthesizing the core and/or the shell, the reaction temperature, the type of ligand connected to the outside of the quantum dot or quantum rod, etc., nanoinorganic The degree of growth and crystal structure of the light-emitting particles may be controlled, and accordingly, emission of light in various wavelength bands may be induced while the energy band gap of the nano-inorganic light-emitting particles is adjusted.

For example, a quantum dot or quantum rod may have a type-I core/shell structure in which an energy bandgap of a core is surrounded by an energy bandgap of a shell. In the case of the type-I core/shell structure, since electrons and holes move toward the core and electrons and holes recombine within the core to emit energy as light, the emission wavelength can be adjusted according to the thickness of the core.

In another exemplary embodiment, quantum dots or quantum rods are type II light-emitting particles in which the band gap energy of the core and the band gap energy of the shell are staggered, so that electrons and holes move in opposite directions between the core and the shell. It may have a core/shell structure. In the case of the type II core/shell structure, the emission wavelength can be adjusted according to the thickness of the shell and the position of the band gap.

In another exemplary embodiment, the quantum dot or quantum rod may have a reverse type-I core/shell structure, which is a light emitting particle structure in which the energy band gap of the core is larger than that of the shell). . In the case of the reverse type-I core/shell structure, the emission wavelength can be adjusted according to the thickness of the shell.

For example, when quantum dots or quantum rods form a type-I core/shell structure, the core is a portion where light emission occurs substantially, and the emission wavelength of the quantum dots or quantum rods is determined according to the size of the core. In order to receive the quantum confinement effect, the core must have a size smaller than the exciton Bohr radius according to each material and have an optical band gap at that size.

The shell constituting the quantum dot or quantum rod promotes the quantum confinement effect of the core and determines the stability of the quantum dot or quantum rod. Atoms exposed on the surface of a colloidal quantum dot or quantum rod of a single structure have an electron state (lone pair electron) that does not participate in chemical bonding unlike internal atoms. The energy levels of these surface atoms are positioned between the conduction band edge and the valence band edge of the quantum dot or quantum rod to trap charges, resulting in surface defects. The luminous efficiency of quantum dots or quantum rods may decrease due to the non-radiative recombination process of excitons caused by surface defects, and the trapped charges react with external oxygen and compounds to form quantum dots or quantum rods. It may cause a change in chemical composition or permanently lose electrical/optical properties of quantum dots or quantum rods.

In order for the shell to be efficiently formed on the surface of the core, the lattice constant of the material constituting the shell should be similar to that of the material constituting the core. By surrounding the surface of the core with a shell, oxidation of the core is prevented, chemical stability of the quantum dots or quantum rods is improved, and photodeterioration of the core due to external factors such as water or oxygen can be prevented. In addition, it is possible to improve quantum efficiency by minimizing loss of excitons due to surface traps on the surface of the core and preventing energy loss due to molecular vibration.

In one exemplary embodiment, the core and the shell may be semiconductor nanocrystals or metal oxide nanocrystals having a quantum confinement effect. For example, semiconductor nanocrystals capable of forming cores and/or shells include group II-VI compound semiconductor nanocrystals of the periodic table, group III-V compound semiconductor nanocrystals of the periodic table, group IV-VI compound semiconductor nanocrystals of the periodic table, and periodic table I -III-VI compound may be selected from the group consisting of semiconductor nanocrystals and combinations thereof.

Specifically, the periodic table II-VI compound semiconductor nanocrystals capable of forming a core and / or a shell are MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe , ZnTe, ZnSeS, ZnTeSe, ZnO, CdS, CdSe, CdTe, CdSeS, CdZnS, CdSeTe, CdO, HgS, HgSe, HgTe, CdZnTe, HgCdTe, HgZnSe, HgZnTe, CdS/ZnS, CdS/ZnSe, CdSe/ZnS, CdSe /ZnSe, ZnSe/ZnS, ZnS/CdSZnS, CdS/CdZnS/ZnS, ZnS/ZnSe/CdSe, and combinations thereof. Group III-V compound semiconductor nanocrystals capable of forming cores and/or shells are AlN, AlP, AlAs, AlSb, GaN, GaP, Ga ₂ O ₃ , GaAs, GaSb, InN, In ₂ O ₃ , InP, InAs, InSb, AlGaAs, InGaAs, InGaP, AlInAs, AlInSb, GaAsN, GaAsP, GaAsSb, AlGaN, AlGaP, InGaN, InAsSb, InGaSb, AlGaInP, AlGaAsP, InGaAsP, InGaAsSb, InAsSbP, AlInAsP, AlGaAsN, InGaAsN, InAlAsN, GaAsSbN, It may be selected from the group consisting of GaInNAsSb and combinations thereof.

Group IV-VI compound semiconductor nanocrystals capable of forming cores and/or shells are TiO ₂ , SnO ₂ , SnS, SnS ₂ , SnTe, PbO, PbO ₂ , PbS, PbSe, PbTe, PbSnTe, and combinations thereof. It can be selected from the constituting group. In addition, the periodic table group I-III-VI compound semiconductor nanocrystals capable of forming a core and/or a shell are AgGaS ₂ , AgGaSe ₂ , AgGaTe 2 , AgInS ₂ , CuInS ₂ , CuInSe _{2 ,} Cu ₂ SnS ₃ , CuGaS ₂ , It may be selected from the group consisting of CuGaSe ₂ and combinations thereof.

Optionally, the core and/or the shell may be formed of compound semiconductor nanocrystals of different groups, such as group III-V compound semiconductor nanocrystals of the periodic table, such as InP/ZnS, InP/ZnSe, and GaP/ZnS, and compound semiconductor nanocrystals of group II-VI compound semiconductor nanocrystals of the periodic table. Crystals may form multiple layers.

In addition, the metal oxide nanocrystals capable of forming the core and/or the shell may be group II or III metal oxide crystals of the periodic table. For example, the metal oxide nanocrystals that can be applied to the core and/or the shell may be selected from the group consisting of MgO, CaO, SrO, BaO, Al ₂ O ₃ and combinations thereof.

If necessary, the semiconductor nanocrystal constituting the core and/or the shell may be doped or undoped with a rare earth element such as Eu, Er, Tb, Tm, Dy or any combination thereof, or Mn, Cu, Ag , transition metal elements such as Al, Mg or any combination thereof.

For example, the core constituting the quantum dot or quantum rod is ZnSe, ZnTe, CdSe, CdTe, InP, ZnCdS, Cu _x In _1-x S, Cu _x In _1-x Se, Ag _x In _1-x S and these It may be selected from the group consisting of a combination of. In addition, the shell constituting the quantum dot or quantum rod is ZnS, GaP, CdS, ZnSe, CdS/ZnS, ZnSe/ZnS, ZnS/ZnSe/CdSe, GaP/ZnS, CdS/CdZnS/ZnS, ZnS/CdSZnS, Cd _X Zn It may be selected from the group consisting of _1-x S and combinations thereof.

On the other hand, quantum dots or quantum rods are alloy quantum dots/quantum rods such as homogeneous alloy quantum dots/quantum rods or gradient alloy quantum dots/quantum rods (alloy QDs/alloy QRs; for example, CdS _x Se _{1- x} , CdSe _x Te _1-x , Zn _x Cd _1-x Se).

When the light emitting material layer 350 is made of inorganic light emitting particles such as quantum dots or quantum rods, the first charge transfer layer 340, for example, the hole transport layer ( 344), the light emitting material layer 350 is formed by volatilizing the solvent.

In one exemplary embodiment, the light emitting material layer 350 is coated on the first charge transfer layer 340 through a solution process of coating a dispersion containing quantum dots or quantum rods, which are light emitting nanoparticles, in a solvent, and It can be formed by volatilizing. As a method of forming the light emitting material layer 350, solution processes such as spin coating, drop coating, dip coating, spray coating, roll coating, flow coating, casting, screen printing, or inkjet printing may be used alone or in combination.

In one exemplary embodiment, the light emitting material layer 350 may include quantum dots or quantum rods, which are nano-inorganic light emitting particles having PL light emission characteristics of 440 nm, 530 nm, and 620 nm, to manufacture a white light emitting diode. Optionally, the light-emitting material layer 350 includes quantum dots or quantum rods, which are light-emitting nanoparticles having any one color among red, green, and blue, and may be implemented to individually emit light in any one of them.

In another alternative embodiment, the light emitting material layer 350 may be made of an organic light emitting material. When the light emitting material layer 350 is made of an organic light emitting material, it is not particularly limited as long as it is a commonly used organic light emitting material. For example, the light-emitting material layer 350 may be made of an organic light-emitting material that emits red, green, and/or blue light, and may include a fluorescent material or a phosphorescent material. In addition, the organic light emitting material constituting the light emitting material layer 350 may include a host and a dopant. When the organic light emitting material is composed of a host-dopant system, the dopant may be doped in an amount of 1 to 50% by weight, preferably 1 to 30% by weight, based on the weight of the host, but the present invention is not limited thereto.

An organic host used in the light emitting material layer 350 is not particularly limited as long as it is a material commonly used. For example, the organic host used for the light emitting material layer 350 is tris(8-hydroxyquinoline)aluminum ; Alq ₃ ), TCTA, PVK, 4,4'-bis(N- Carbazolyl) -1,1'-biphenyl (4,4'-bis (N-carbazolyl) -1,1'-biphenyl; CBP), 4,4'-bis (9-carbazolyl) -2,2 '-dimethylbiphenyl (4,4'-Bis (9-carbazolyl) -2,2'-dimethylbiphenyl; CDBP), 9,10-di (naphthalen-2-yl) anthracene (9,10-di (naphthalene- 2-yl) anthracene; ADN), 3-tert-butyl-9,10-di (naphtha-2-yl) anthracene (3-tert-butyl-9,10-di (naphtha-2-yl) anthracene; TBADN), 2-methyl-9,10-bis (naphthalen-2-yl) anthracene (2-methyl-9,10-bis (naphthalene-2-yl) anthracene; MADN), 1,3,5-tris ( N-phenylbenzimidazole-2-yl)benzene (1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene, TPBi), distyrylarylene (DSA), mCP, 1,3, 5-tris (carbazol-9-yl) benzene (1,3,5-tris (carbazol-9-yl) benzene; TCP) and the like.

When the light emitting material layer 350 emits red light, dopants included in the light emitting material layer 350 include 5,6,11,12-tetraphenylnaphthalene (Rubrene), bis (2-benzo[b]thiophene-2-yl-pyridine)(acetylacetonate)iridium(III)(Bis(2-benzo[b]-thiophene-2-yl-pyridine)(acetylacetonate)iridium(III) Ir(btp) ₂ (acac)), bis[1-(9,9-dimethyl-9H-fluoren-2-yl)-isoquinoline](acetylacetonate)iridium(III)(Bis[1-( 9,9-diemthyl-9H-fluorn-2-yl)-isoquinoline](acetylacetonate)iridium(III);Ir(fliq) ₂ (acac)), bis[2-(9,9-dimethyl-9H-fluorene) -2-yl)-quinoline](acetylacetonate)iridium(III)(Bis[2-(9,9-diemthyl-9H-fluorn-2-yl)-quinoline](acetylacetonate)iridium(III); Ir(flq) ₂ (acac)), bis(2-phenylquinoline)(2-(3-methylphenyl)pyridinate)iridium(III)(Bis-(2-phenylquinoline)(2-(3-methylphenyl)pyridinate)irideium(Ⅲ ); Ir (phq) ₂ typ), iridium (III) bis (2- (2,4-difluorophenyl) quinoline) picolinate ) picolinate; FPQIrpic) may include organic compounds or organic metal complexes, but the present invention is not limited thereto.

When the light emitting material layer 350 emits green light, dopants included in the light emitting material layer 350 include N,N'-dimethyl-quinacridone (DMQA), coumarin 6, 9,10-bis[N,N-di-(p-tolyl)-amino]anthracene (9,10-bis[N,N-di-(p-tolyl)amino]anthracene; TTPA), 9,10- Bis[phenyl(m-tolyl)amino]anthracene (9,10-bis[phenyl(m-tolyl)-amino]anthracene; TPA), bis(2-phenylpyridine)(acetylacetonate)iridium(III)(bis (2-phenylpyridine)(acetylacetonate)iridium(III); Ir(ppy) ₂ (acac)), fac-tris(2-phenylpyridine)iridium(III)(fac-tris(phenylpyridine)iridium(III); fac- organic compounds such as Ir(ppy) ₃ ), tris[2-(p-tolyl)pyridine]iridium(III) (tris[2-(p-tolyl)pyridine]iridium(III); Ir(mppy) ₃ ); It may include an organometallic complex, but the present invention is not limited thereto.

When the light emitting material layer 350 emits blue light, the dopant included in the light emitting material layer 350 is 4,4'-bis[4-(di-p-tolylamino)stryl]biphenyl(4,4 '-bis[4-(di-p-tolylamino)styryl]biphenyl; DPAVBi), perylene, 2,5,8,11-tetra-tert-butylperylene (2,5,8,11- tetra-tert-butylpherylene; TBPe), bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III)(bis(3,5-difluoro-2 -(2-pyridyl)phenyl-(2-carbozylpyridyl)iridium(III); FirPic), mer-tris(1-phenyl-3-methylimidazolin-2-ylidene-C,C2')iridium(III) (mer-tris(1-phenyl-3-methylimidazolin-2ylidene-C,C2')iridium(III); mer-Ir(pmi) ₃ ), tris(2-(4,6-difluorophenyl)pyridine) Iridium (III) (tris (2- (4,6-difluorophenyl) pyridine) iridium (III); Ir (Fppy) ₃ ) may include organic compounds or organic metal complexes, but the present invention is not limited thereto. .

If necessary, when the light emitting material layer 350 is made of an organic light emitting material, the light emitting material layer 350 may include a delayed fluorescent material.

When the light emitting material layer 350 is made of an organic light emitting material, the light emitting material layer 350 may be formed by a vacuum deposition process including vacuum vapor deposition or sputtering, spin coating, drop coating, dip coating, spray coating, roll coating, Solution processes such as flow coating, casting process, screen printing or inkjet printing may be used alone or in combination.

For example, the light emitting material layer 350 may be formed to a thickness of 5 to 300 nm, preferably 10 to 200 nm, but the present invention is not limited thereto.

According to an exemplary embodiment, the light emitting material layer 350 may include inorganic light emitting particles such as quantum dots or quantum rods. When the luminance is increased by increasing the current density or driving voltage of the light emitting diode 300, the organic light emitting material may be degraded. In the case of implementing light emission, the light emitting material layer made of an organic light emitting material is easily decomposed, and thus the lifespan of light emission may be reduced.

Meanwhile, the second charge transfer layer 360 is positioned between the light emitting material layer 350 and the second electrode 320 . In this embodiment, the second charge transfer layer 360 may be an electron transfer layer supplying electrons to the light emitting material layer 350 . In one exemplary embodiment, the second charge transfer layer 360 is an electron injection layer disposed adjacent to the second electrode 320 between the second electrode 320 and the light emitting material layer 350. ;

The electron injection layer 362 facilitates electron injection from the second electrode 320 into the light emitting material layer 350 . For example, the electron injection layer 362 is made of a material in which fluorine is doped or combined with a metal such as Al, Cd, Cs, Cu, Ga, Ge, In, or Li, or Al, Mg, In, Li, or Ga. Titanium dioxide (TiO ₂ ), zinc oxide (ZnO), zirconium oxide (ZrO), tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), tantalum oxide (Ta ₂ O ₃ ).

The electron transport layer 364 transfers electrons to the light emitting material layer 350 . The electron transport layer 364 may be made of an inorganic material and/or an organic material. In one exemplary embodiment, when the light emitting material layer 350 is made of inorganic light emitting particles, the electron transport layer 364 prevents interface defects with the light emitting material layer 350 to secure stability when driving the device. ) may be made of an inorganic material. When the electron transport layer 364 is made of an inorganic material having excellent charge mobility, the transfer rate of electrons provided from the second electrode 320 can be improved and the electron concentration is high, so that the light emitting material layer 350 electrons can be transported efficiently.

In addition, when the light emitting material layer 350 is composed of inorganic light emitting particles, the valence band (VB) energy level of the inorganic light emitting particles corresponding to the highest occupied molecular orbital (HOMO) of the organic compound is very deep. In general, the HOMO energy level of organic compounds having electron transport characteristics is shallower than the valence band (VB) energy level of inorganic light-emitting particles. In this case, holes injected from the first electrode 310 into the light emitting material layer 350 made of inorganic light emitting particles pass through the electron transport layer 364 made of organic compounds and leak to the second electrode 320. may occur.

Accordingly, in one exemplary embodiment, the electron transport layer 364 may be formed of an inorganic material having a relatively deep valence band (VB) energy level. Preferably, the energy band gap (Eg) between the valence band (VB) energy level and the conduction band energy level corresponding to the lowest unoccupied molecular orbital (LUMO) energy level of the organic compound This wide inorganic material can be used as a material for the electron transport layer 364. In this case, holes injected into the light emitting material layer 350, which may be made of an inorganic light emitting material, do not leak to the electron transport layer 364, and electrons provided from the second electrode 320 efficiently penetrate the light emitting material layer 350. can be injected into

When the electron transport layer 364 is made of an inorganic material, the electron transport layer 364 may be a metal oxide doped or undoped with Al, Mg, In, Li, Ga, Cd, Cs, Cu, or the like; semiconductor particles doped or undoped with Al, Mg, In, Li, Ga, Cd, Cs, Cu or the like; and an inorganic material selected from the group consisting of metal nitrides and combinations thereof.

For example, the metal oxide forming the electron transport layer 364 is zinc (Zn), calcium (Ca), magnesium (Mg), titanium (Ti), tin (Sn), tungsten (W), tantalum (Ta), hafnium It may include an oxide of a metal selected from the group consisting of (Hf), aluminum (Al), zirconium (Zr), barium (Ba), and combinations thereof. More specifically, the metal oxide forming the electron transport layer 364 is titanium oxide (TiO ₂ ), zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), zinc calcium oxide (ZnCaO), zirconium oxide (ZrO ₂ ), tin Oxide (SnO ₂ ), tin magnesium oxide (SnMgO), tungsten oxide (WO ₃ ), tantalum oxide (Ta ₂ O ₃ ), hafnium oxide (HfO ₃ ), aluminum oxide (Al ₂ O ₃ ), barium titanium oxide (BaTiO ₃ ), barium zirconium oxide (BaZrO ₃ ), and combinations thereof, but the present invention is not limited thereto.

Other inorganic materials capable of forming the electron transport layer 364 include semiconductor particles such as CdS, ZnSe, and ZnS doped or undoped with Al, Mg, In, Li, Ga, Cd, Cs, or Cu; It includes an inorganic material selected from the group consisting of nitrides such as Si ₃ N ₄ and combinations thereof.

On the other hand, when the electron transport layer 364 is made of an organic material, the electron transport layer 364 includes an oxazole-based compound, an isoxazole-based compound, a triazole-based compound, an isothiazole-based compound, an oxadiazole-based compound, a thiadiazole-based compound, and phenanthroline. An organic material such as a phenanthroline-based compound, a perylene-based compound, a benzoxazole-based compound, a benzothiazole-based compound, a benzimidazole-based compound, a triazine-based compound, or an aluminum complex may be used. Specifically, the organic material capable of constituting the electron transport layer 464 is 3-(biphenyl-4-yl)-5-(4-tetrabutylphenyl)-4-phenyl-4H-1,2,4-tria. Sol (3-(biphenyl-4-yl)-5-(4-tertbutylphenyl)-4-phenyl-4H-1,2,4-triazole, TAZ), bathocuproine ( 2,9-dimethyl- 4,7-diphenyl-1,10-phenanthroline; BCP), 2,2',2"-(1,3,5-benzyntriyl)-tris(1-phenyl-1-H-benzimiazole) ( 2,2',2 "-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole); TPBi), Tris(8-hydroxyquinoline) aluminum ( Tris(8-hydroxyquinoline) )aluminum; Alq ₃ ), bis(2-methyl-8-quinolinato)-4-phenylphenolate aluminum(III) (bis(2-methyl-8-quninolinato)-4-phenylphenolatealuminum (III); Balq) , selected from materials consisting of bis(2-methyl-quinolinato)(triphenylsiloxy) aluminum(III) (Salq) and combinations thereof It may be, but the present invention is not limited thereto.

Similar to the first charge transfer layer 340, the second charge transfer layer 360 in FIG. 2 is shown as two layers of an electron injection layer 362 and an electron transport layer 364, but the second charge transfer layer 360 ) may be formed of only one layer of the electron transport layer 364. In addition, the second charge transfer layer 360 may be formed with one layer of the electron transport layer 364 obtained by blending cesium carbonate with the aforementioned inorganic electron transport material.

The second charge transfer layer 360 including the electron injection layer 362 and/or the electron transport layer 364 may be formed by a vacuum deposition process such as vacuum vapor deposition or sputtering, spin coating, drop coating, dip coating, spray coating, It may be formed by using a solution process such as roll coating, flow coating, casting process, screen printing or inkjet printing alone or in combination. For example, each of the electron injection layer 362 and the electron transport layer 364 may be laminated to a thickness of 10 to 200 nm, preferably 10 to 100 nm, but the present invention is not limited thereto.

On the other hand, when a hybrid charge transfer layer is introduced in which the hole transport layer 344 constituting the first charge transfer layer 340 is made of an organic material and the second charge transfer layer 360 is made of an inorganic material, the light emitting diode 300 The luminous properties of can be improved.

In an alternative embodiment, the lifetime of the device is determined when holes move through the light emitting material layer 350 to the second electrode 320 or when electrons move through the light emitting material layer 350 to the first electrode 310. and can reduce efficiency. To prevent this, in the light emitting diode 300 according to the exemplary embodiment of the present invention, at least one exciton blocking layer may be positioned adjacent to the light emitting material layer 350 .

For example, the quantum dot light emitting diode 300 according to the exemplary embodiment of the present invention is an electron blocking layer capable of controlling or preventing the movement of electrons between the hole transport layer 344 and the light emitting material layer 350. layer, EBL; not shown) may be located. For example, the electron blocking layer (not shown) is TCTA, tris [4- (diethylamino) phenyl] amine (tris [4- (diethylamino) phenyl] amine), N- (biphenyl-4-yl) - 9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, tri-p-tolylamine , 1,1-bis (4- (N, N-di (p-tolyl) amino) phenyl) cyclohexane (1,1-bis (4- (N, N'-di (ptolyl) amino) phenyl) cyclohexane TAPC), m-MTDATA, 1,3-bis (N-carbazolyl) benzene (1,3-bis (N-carbazolyl) benzene; mCP), 3,3'-bis (N-carbazolyl) -1 , 1'-biphenyl (3,3'-bis (N-carbazolyl) -1,1'-biphenyl; mCBP), Poly-TPD, copper phthalocyanine (CuPc), DNTPD and / or 1,3, 5-tris [4- (diphenylamino) phenyl] benzene (1,3,5-tris [4- (diphenylamino) phenyl] benzene; TDAPB) and the like.

In addition, a hole blocking layer (HBL, not shown) is positioned as a second exciton blocking layer between the light emitting material layer 350 and the electron transporting layer 364, so that the light emitting material layer 350 and the electron transporting layer 364 ) can prevent the movement of holes between them. In one exemplary embodiment, an oxazole-based compound, an isoxazole-based compound, a triazole-based compound, an isothiazole-based compound, or an oxadiazole-based compound that can be used for the electron transport layer 364 as a material for a hole blocking layer (not shown) , thiadiazole-based compounds, phenanthroline-based compounds, perylene-based compounds, benzoxazole-based compounds, benzothiazole-based compounds, benzimidazole-based compounds, triazine-based compounds, or organic materials such as aluminum complexes may be used. can

For example, the hole blocking layer (not shown) is 2,9-dimethyl-4,7-diphenyl-1,10- which has a deep (low) HOMO energy level compared to the material used for the light emitting material layer 350. phenanthroline (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline; BCP), BAlq, Alq3, PBD, spiro-PBD, and/or Liq.

Meanwhile, according to the first exemplary embodiment of the present invention, the charge control layer 370 is positioned between the second electron transfer layer 360, which may be an electron transfer layer, and the second electrode 320. For example, using an inorganic material instead of an organic material as a material for the electron transport layer 364 is advantageous in terms of charge injection because the driving voltage of the light emitting diode 300 is reduced and electron mobility is excellent.

In the case of using an inorganic material as a material for the electron transport layer 364 , electrons are charged by internal defects of the inorganic material, and electrons are accumulated in the electron transport layer 364 . As a result, a charging trap of electrons or an exciton trap occurs. The electrons accumulated in the electron transport layer 364 also affect the light emitting materials constituting the adjacent light emitting material layer 350, so that the light emitting material layer 350 is also charged. Accordingly, the light emitting diode 300 is not driven efficiently, and thus the light emitting efficiency of the light emitting diode 300 is lowered and the light emitting life is shortened.

However, according to the first embodiment of the present invention, the second charge transfer layer 360, for example, between the electron transport layer 364 and the second electrode 320 includes a conductive material and a material having a wide energy band gap. A charge control layer 370 is introduced. Due to the introduced charge control layer 370, accumulation of electrons due to internal defects of the electron transport material may be prevented, and charge capture due to accumulation of electrons may be prevented. In addition, electrons and holes may be injected into the light emitting material layer 350 in a balanced manner.

The charge control layer 370 may include a first material that is a conductive polymer and a second material that has a relatively wide energy band gap. The conductive polymer prevents the generation of static electricity caused by the charge of electrons due to internal defects of the material constituting the electron transport layer 364 . For example, the conductive polymer that is the first material forming the charge control layer 370 is polyphenylene, polyphenylenesulfide, or poly(ethylenedioxythiophene): It may be selected from the group consisting of polystyrenesulfonate (PEDOT:PSS), polyaniline (PAN), polypyrrole (PPy), polythiophene (PT), polyacetylene (polyacethylene), and combinations thereof. .

The second material may be made of a material having a wide energy band gap. In one exemplary embodiment, the second material may be a material having a wider energy band gap than an inorganic material constituting the electron transport layer 364 . For example, when the electron transport layer 364 is made of a metal oxide, the valence band (VB) energy level of an inorganic metal oxide corresponding to the highest occupied molecular orbital (HOMO) energy level of an organic material is approximately -7.7 to -7.3 eV. In addition, the conduction band (CB) energy level of an inorganic metal oxide corresponding to the lowest unoccupied molecular orbital (LUMO) energy level of an organic material is approximately -4.2 to -3.7 eV.

The second material having a wider energy band gap than these metal oxides may be selected from the group consisting of cured siloxanes, (meth)acrylate-based polymers, vinyl alcohol-based polymers, and combinations thereof. In this specification, a (meth)acrylate system is used to refer to both an acrylate system and a methacrylate system.

In an exemplary embodiment, the cured siloxane, which is the second material constituting the charge control layer 370, may be synthesized from a silane monomer represented by Chemical Formula 1 below.

[Formula 1]

In Formula 1, R ₁ and R ₂ are each independently hydrogen, deuterium, tritium, a hydroxy group, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₂ ~ C ₁₀ alkenyl group, C ₁ ~ C ₁₀ alkoxy group , C ₁ ~ C ₁₀ alkyl amino group, C ₁ ~ C ₁₀ alkyl acryloxy group, C ₁ ~ C ₁₀ alkyl methacryloxy group, thiol group, C ₁ ~ C ₁₀ alkyl thiol group, epoxy group, C ₁ ~ C ₁₀ alkyl Epoxy group, C ₅ ~ C ₂₀ cycloalkyl epoxy group, C ₄ ~ C ₂₀ heteroaryl epoxy group, glycidyloxy group, C ₁ ~ C ₁₀ alkyl glycidyloxy group, unsubstituted or halogen atom-substituted C ₅ ~ C ₂₀ aryl group , C ₄ ~ C ₂₀ heteroaryl group, C ₅ ~ C ₂₀ aryloxy group, C ₄ ~ C ₂₀ heteroaryloxy group, C ₅ ~ C ₂₀ aryl amino group and C ₅ ~ C ₂₀ hetero group, unsubstituted or substituted with a halogen atom selected from the group consisting of aryl amino groups; R ₃ and R ₄ are each independently hydrogen, deuterium, tritium, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₁ ~ C ₁₀ alkyl amino group, unsubstituted or halogen atom-substituted C ₅ ~ C ₂₀ aryl group, Selected from the group consisting of an unsubstituted or halogen atom-substituted C ₅ ~C ₂₀ heteroaryl group, a C ₅ ~C ₂₀ aryl amino group, and a C ₅ ~C ₂₀ heteroaryl amino group.

In an exemplary embodiment, the C ₁ to C ₁₀ linear or branched alkyl group constituting R ₁ to R ₄ may preferably be a C ₁ to C ₅ straight or branched alkyl group. In another exemplary embodiment, the C ₅ ~ C ₂₀ aryl group constituting R ₁ to R ₄ , respectively, is a phenyl group, a biphenyl group, a terphenyl group, a tetraphenyl group, a naphthyl group, an anthracenyl group, an indenyl group, a phenalenyl group, or a phenanthrene group. It may include an uncondensed or fused aromatic functional group such as a yl group, an azulenyl group, a pyrenyl group, a fluorenyl group, a tetracenyl group, an indacenyl group, or a spiro fluorenyl group, preferably a phenyl group, A biphenyl group, a naphthyl group, an anthracenyl group, or an indenyl group may be included. However, the present invention is not limited thereto.

In addition, the C ₄ ~ C ₂₀ heteroaryl group constituting R ₁ to R ₄ is a furanyl group, a thiophenyl group, a pyrrolyl group, a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, and a tetrazinyl group. group, imidazolyl group, pyrazolyl group, indolyl group, carbazolyl group, benzocarbazolyl group, dibenzocarbazolyl group, indolocarbazolyl group, indenocarbazolyl group, benzofuranocarbazolyl group, benzothieno Carbazolyl group, quinolinyl group, isoquinolinyl group, phthalazinyl group, quinoxalinyl group, cynolinyl group, quinazolinyl group, benzoquinolinyl group, benzoisoquinolinyl group, benzoquinazolinyl group, benzoquinoxalinyl group , acridinyl group, phenanthrolinyl group, furanyl group, pyranyl group, oxazinyl group, oxazolyl group, isoxazolyl group, oxadiazolyl group, triazolyl group, dioxynyl group, benzofuranyl group, dibenzofuranyl group , A thiopyranyl group, a thiazinyl group, a thiophenyl group, a benzothiophenyl group, a dibenzothiophenyl group, a thiazolyl group, or a heteroaromatic functional group such as an isothiazolyl group, preferably a pyridyl group or a pyrimidyl group can include However, the present invention is not limited thereto.

For example, in Formula 1, R ₁ is hydrogen, deuterium, tritium, a hydroxyl group, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₂ ~ C ₁₀ alkenyl group, C ₁ ~ C ₁₀ alkoxy group, C ₁ ~C ₁₀ alkyl amino group, C ₁ ~C ₁₀ alkyl acryloxy group, C ₁ ~C ₁₀ alkyl methacryloxy group, thiol group, C ₁ ~C ₁₀ alkyl thiol group, C ₁ ~C ₁₀ alkyl glycidyloxy group, and C ₅ ~ C ₂₀ It is selected from the group consisting of an aryl group; R ₂ is selected from the group consisting of a hydroxy group and a C ₁ to C ₁₀ alkoxy group; R ₃ and R ₄ may be each independently selected from the group consisting of hydrogen, deuterium, tritium, and C ₁ to C ₁₀ linear or branched alkyl groups.

In one exemplary embodiment, a silane monomer that can be synthesized from a cured siloxane, which is one of the second materials constituting the charge control layer 370, has a central silicon atom (Si) containing at least three alkoxy groups, aryloxy groups, It may be a compound substituted with a group and/or a hetero aryloxy group. That is, at least one of R ₁ and R ₂ in Formula 1 may be a C ₁ ~ C ₁₀ alkoxy group, a C ₅ ~ C ₂₀ aryloxy group, and/or a C ₄ ~ C ₂₀ heteroaryloxy group. Preferably, at least one of R ₁ and R ₂ is a C ₁ -C ₁₀ alkoxy group, and R ₃ and R ₄ may be a straight-chain or branched C ₁ -C ₁₀ alkyl group.

For example, the silane monomer represented by Chemical Formula 1 may include silanes having 2 to 4 alkoxy groups. For example, silanes having two alkoxy groups include dimethyldiethoxysilane (DMDES), methyl (vinyl) diethoxysilane (MVDES), 3-aminopropyl (methyl) diethoxysilane ( 3-Aminopropyl(methyl)diethoxysilane; APMDES), (3-Acryloxypropyl)methyldimethoxysilane; APDMS), 3-glycidoxypropyl(methyl)diethoxysilane (3-glycidoxylpropyl( methyl)diethoxysilane; GPMDES) and/or methyl(phenyl)diethoxysilane; MPDES).

On the other hand, silanes having three alkoxy groups include methyltriethoxysilane (MTES), octyltriethoxysilane (OTES), vinyltriethoxysilane (VTES), 3-aminopropyltrimethoxy Silane (3-Aminopropyltrimethoxysilane; APTMS), 3-Aminopropyltriethoxysilane (APTES), 3-(2-Aminoethylamino)propyltrimethoxysilane (3-(2-Aminoethylamino)propyltrimethoxysilane; AEPTMS ), (3-acryloxypropyl)trimethoxysilane ((3- Acryloxypropyl)trimethoxysilane; APTMS), methacryloxymethyltriethoxysilane (MMS), 3-methacryloxypropyltrimethoxysilane (3 -Methacryloxypropyltrimethoxysilane (MPTMS), 3-methacryloxypropyltriethoxysilane (MPTES), 3-Mercaptopropyltriethoxysilane (MPTES), 2-(3,4-epoxycyclo Hexyl) ethyltriethoxysilane (2- (3,4-Epoxycyclohexyl) ethyltriethoxysilane; ECETMS), 3-Glycidyloxypropyltrimethoxysilane (GPTMOS), 3-glycidyloxypropyltriethene Toxysilane (3-Glycidyloxypropyltriethoxysilane; GPTEOS), phenyltrimethoxysilane (PTES) and/or [3-(phenylamino)propyl]trimethoxysilane ([3-(phenylamino)propyl]trimethoxysilane; PAPTMS) Including, but not limited to.

In addition, silane monomers (ie, silicates) having four alkoxy groups are tetramethylorthosilicate (TMOS, tetramethoxysilane), tetraethylorthosilicate (TEOS, tetraethoxysilane), tetrapropylortho silicate (tetrapropylorthosilicate, tetrapropoxysilane), tetrabutylorthosilicate (tetrabutylorthosilicate, tetrabutoxysilane), tetrapentylorthosilicate (tetrapentylorthosilicate, tetrapentoxysilane), and the like, but the present invention is not limited thereto.

For example, among the silane monomers represented by Chemical Formula 1, silane monomers having three or more alkoxy groups, aryloxy groups, and/or heteroaryloxy groups are converted into silanol having three or more hydroxyl groups during hydrolysis. Among them, 2 to 3 hydroxy groups may form a siloxane cured product through a self-condensation reaction. As an example, the cured siloxane may be represented by Formula 2 below.

[Formula 2]

In Formula 2, R ₁ to R ₄ are as defined in Formula 1; n is an integer greater than or equal to 1;

On the other hand, the (meth)acrylate-based polymer, which is one of the second materials, includes polymethylmethacrylate (PMMA), and the vinyl alcohol-based polymer includes polyvinyl alcohol (PVA), but in the present invention, This is not limited to this.

In one exemplary embodiment, the thickness of the charge control layer 370 made of the first material and the second material may be approximately 1 to 10 nm, preferably 1 to 5 nm. When the thickness of the charge control layer 370 exceeds 10 nm, the driving voltage of the light emitting diode 300 may increase excessively.

In one exemplary embodiment, when a cured siloxane is used as the second material, the ratio of the first material, which is a conductive polymer constituting the charge control layer 370, and the cured siloxane (or precursor) is 3:10 to 1 : can be formulated in a volume ratio of 2. Meanwhile, the sheet resistance of the charge control layer 370 may be greater than or equal to 1 MΩ/sq and less than or equal to 10 MΩ/sq. In this case, generation of static electricity due to charge of electrons in the electron transport layer 364 can be prevented, and current leakage can be prevented.

When the content of the first material, which is the conductive polymer, is less than 3:10, the sheet resistance of the charge control layer 370 increases as the content of the conductive polymer is too small, making it difficult to prevent the charge of electrons due to the accumulated electrons.

On the other hand, when the content of the first material, which is a conductive polymer, exceeds 1:2, the content of the conductive polymer is too large and leakage current occurs in the charge control layer 370, which causes the light emitting diode 300 to operate. A lot of current can be consumed before. In addition, since the content of the second material having a wide energy band gap is too small, it may be difficult to achieve a balance of charge injection.

As described above, the hole transport layer 344 forming the light emitting diode 300 may be made of an organic material, and the electron transport layer 364 may be made of an inorganic material. The charge mobility of inorganic materials is higher than that of organic materials. Therefore, as shown in FIG. 3, which is a diagram schematically showing band gap energies of materials constituting an electrode and a light emitting unit constituting a conventional light emitting diode without forming a charge control layer, electrons supplied from the second electrode ( ⓔ ^- ) is rapidly injected into the light emitting material layer (EML) from the electron transport layer (ETL) made of an inorganic material having excellent electron mobility. On the other hand, holes (ⓗ ⁺ ) supplied from the first electrode are slowly injected from the hole transport layer (HTL) made of an organic material having relatively low hole mobility into the light emitting material layer (EML). That is, the injection amount of electrons (ⓔ ^- ) in the light emitting material layer (EML) is greater than the injection amount of holes ( ^- ⓗ ⁺ ).

Since electrons (ⓔ ^- ) and holes (ⓗ ⁺ ) are not balanced (charge un-balancing) in the light emitting material layer (EML), the excessively injected electrons (ⓔ ^- ) recombine with holes to form excitons. It fails to do so and is quenched (electron quenching). Electrons (ⓔ ^- ) and holes (ⓗ ⁺ ) do not recombine in the light emitting material constituting the light emitting material layer (EML), and recombine at the interface between the light emitting material layer (EML) and the electron transport layer (HTL), and electron exciton energy increases. There is a catch issue. Accordingly, the light emitting efficiency of the light emitting diode (300, see FIG. 2) is reduced. In addition, since a high voltage is required to realize desired light emission, power consumption of the light emitting diode increases.

On the other hand, according to the first embodiment of the present invention, the charge control layer 370 including the second material having a wide energy band gap is formed by the second charge transfer layer 360, for example, the electron transport layer 364 and the second material. Located between the electrodes 320, charges can be injected in a balanced manner, which will be described. 4 is a diagram schematically showing bandgap energies of materials constituting an electrode constituting a light emitting diode and a light emitting unit according to an exemplary embodiment of the present invention.

As schematically shown in FIG. 4 , electrons (ⓔ ^- ) supplied from the second electrode must pass through the charge control layer (CCL) before moving to the electron transport layer (ETL). As described above, the charge control layer (CCL) has a wider energy bandgap than inorganic materials such as metal oxide constituting the electron transport layer (ETL).

Among metal oxides, ZnO has a valence band (VB) energy level corresponding to HOMO of -7.46 eV and a conduction band (CB) energy level corresponding to LUMO of -4.26 eV, and an energy band gap of about 3.2 eV. When Mg is mixed with ZnO, the valence band (VB) energy level remains almost the same, but the conduction band (CB) energy level slightly rises and the energy band gap rises in proportion to the amount of Mg mixed. For example, the energy band gap of ZnMgO mixed with 5% Mg in ZnO is 3.29 eV, the energy band gap of ZnMgO mixed with 10% Mg is 3.4 eV, and the energy band gap of ZnMgO mixed with 20% Mg is 3.5 eV. am.

On the other hand, the HOMO energy level (HOMO _CCL ) of the charge control layer (CCL) having the second material having a wide energy band gap is the valence band energy level (VB _ETL ) of the electron transport layer (ETL) made of an inorganic material, for example, a metal oxide. ) can be lower than (deep). In addition, the LUMO energy level (LUMOCCL) of the charge control layer (CCL) may be higher than the conduction band energy level (CB _ETL ) of the electron transport layer (ETL) made of a metal oxide (shallow).

In one exemplary embodiment, the HOMO energy level (HOMO _CCL ) of the charge control layer (CCL) is 0.3 to 1.0 eV, preferably 0.5 to 1.0 eV, higher than the valence band energy level (VB _ETL ) of the electron transport layer (ETL). can be low In addition, the LUMO energy level (LUMO _CCL ) of the charge control layer (CCL) may be 0.3 to 1.0 eV, preferably 0.5 to 1.0 eV higher than the conduction band energy level (CBETL) of the electron transport layer (ETL). Preferably, the energy band gap (Eg _CCL ), which is the difference between the LUMO energy level and the HOMO energy level of the charge control layer (CCL), is the energy band gap, which is the difference between the conduction band energy level and the valence band energy level of the electron transport layer (ETL) (Eg _ETL ) may be greater than 0.5 eV (eg, greater than or equal to 0.5 eV and less than or equal to 1.5 eV).

The charge control layer (CCL) including the second material having a wide energy bandgap may function as an energy barrier in relation to the movement of electrons. The amount of electrons (ⓔ ^- ) supplied from the second electrode to the electron transport layer (ETL) may decrease or the supply speed of electrons (ⓔ ^- ) may be slowed down. As a result, the injected amount of electrons (ⓔ ^- ) and the injected amount of holes ( ^- ⓗ ⁺ ) can be balanced in the light emitting material layer EML. Electrons (ⓔ ^- ) and holes (ⓗ ⁺ ) are injected in a balanced manner from the light emitting material layer (EML), and both electrons (ⓔ ^- ) and holes (ⓗ ⁺ ) injected into the light emitting material layer (EML) recombine to generate excitons. can form Accordingly, the light emitting efficiency of the light emitting diode 300 may be improved. In addition, since it can be driven at a low voltage, power consumption of the light emitting diode 300 can be reduced.

In the first embodiment described above, the charge control layer 370 is positioned between the second charge transfer layer 360 and the second electrode 320 . Alternatively, the charge control layer may be positioned between the light emitting material layer and the second charge transfer layer. 5 is a schematic cross-sectional view of a light emitting diode according to a second exemplary embodiment of the present invention, showing the light emitting diode having a normal structure.

As shown in FIG. 5, the light emitting diode 400 according to the second exemplary embodiment of the present invention includes a first electrode 410, a second electrode 420 facing the first electrode 410, a first A light emitting unit 430 including a light emitting material layer 450 positioned between the electrode 410 and the second electrode 420 is included. The light emitting unit 430 is positioned between the first charge transfer layer 440 positioned between the first electrode 410 and the light emitting material layer 450 and between the second electrode 420 and the light emitting material layer 450. It further includes a second charge transfer layer 460 to do, and a charge control layer 470 positioned between the light emitting material layer 450 and the second charge transfer layer 460.

In the second embodiment of the present invention, the first electrode 410 may be a hole injection electrode, and the second electrode 420 may be an electron injection electrode. The first charge transfer layer 440 may be a hole transfer layer and may include a hole injection layer 442 and a hole transport layer 444 . The light emitting material layer 450 may be formed of inorganic light emitting particles such as quantum dots or quantum rods, or may be formed of organic light emitting materials such as a host and a dopant. The second charge transfer layer 460 may be an electron transfer layer and may include an electron injection layer 462 and an electron transport layer 464 .

In an alternative embodiment, the light emitting diode 400 includes an electron blocking layer (not shown) and/or a light emitting material layer capable of controlling and preventing the movement of electrons between the hole transport layer 444 and the light emitting material layer 450. At least one exciton blocking layer such as a hole blocking layer (not shown) capable of controlling or preventing the movement of holes may be further included between 450 and the electron transport layer 464 .

Since these configurations are substantially the same as the configurations and functions described in the first embodiment of the present invention, detailed descriptions are omitted.

In the second embodiment of the present invention, the charge control layer 470 is located between the light emitting material layer 450 and the second charge transfer layer 460, for example, the electron transport layer 464. Similar to the first embodiment, the charge control layer 470 may be formed of a first material that is a conductive polymer and a second material that has a wide energy band gap.

For example, the first material, which is a conductive polymer, is polyphenylene, polyphenylenevinylene, polyphenylene sulfide, poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, polythiophene. , polyacetylene, and combinations thereof. The second material having a wide energy band gap may be selected from the group consisting of cured siloxanes, (meth)acrylate-based polymers, vinyl alcohol-based polymers, and combinations thereof. For example, the cured siloxane may be synthesized from a silane monomer represented by Formula 1, a silane monomer in which at least three C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms, eg, four C ₁ to C ₁₀ alkoxy groups. It can be synthesized from silane monomers in which groups are bonded to silicon atoms.

Since the charge control layer 470 includes a first material that is a conductive polymer, it is possible to prevent charge trapping in which electrons are accumulated in the electron transport layer 464 due to internal defects of the electron transport layer 464 . In addition, the charge control layer 470 including a second material having a wide energy bandgap may function as an energy barrier related to electron injection. Accordingly, holes supplied from the first electrode 410 to the light emitting material layer 450 via the first charge transfer layer 440 and holes supplied from the second electrode 420 via the second charge transfer layer 460 Thus, electrons supplied to the light emitting material layer 450 can be injected in a balanced manner. By preventing charge trapping of electrons due to excessively accumulated electrons and preventing electrons excessively injected into the light emitting material layer 450 from recombination, the light emitting efficiency of the light emitting diode 400 is improved and power consumption is reduced. can be lowered

Meanwhile, in the above-described embodiment, the hole transfer layer is positioned between the light emitting material layer and the first electrode having a relatively low work function, and the electron transfer layer is disposed between the light emitting material layer and the second electrode having a relatively high work function. A quantum dot light emitting diode having a normal structure at this location has been described. A light emitting diode may have an inverted structure rather than a normal structure, which will be described. 6 is a schematic cross-sectional view of a light emitting diode according to a third exemplary embodiment of the present invention, showing the light emitting diode having an inverted structure.

As shown in FIG. 6, the light emitting diode 00 according to the third exemplary embodiment of the present invention includes a first electrode 510, a second electrode 520 facing the first electrode 510, and a first electrode and a light emitting layer 530 including a light emitting material layer 550 positioned between the electrode 510 and the second electrode 520 . The light emitting layer 530 includes a first charge transfer layer 540 positioned between the first electrode 510 and the light emitting material layer 550, and positioned between the second electrode 520 and the light emitting material layer 550. A second charge transfer layer 560 and a charge control layer 570 positioned between the first electrode 510 and the first charge transfer layer 540 are further included.

The first electrode 510 may be a cathode such as an electron injection electrode. For example, the first electrode 510 is ITO, IZO, ITZO, ICO, SnO ₂ , In ₂ O ₃ , Cd:ZnO, F:SnO ₂ , In:SnO _{2 , Ga:SnO 2 ,} and doped such as AZO or It may be an undoped metal oxide or a material including nickel (Ni), platinum (Pt), gold (Au), silver (Ag), iridium (Ir), or carbon nanotubes in addition to the above-mentioned metal oxide.

The second electrode 520 may be an anode such as a hole injection electrode. For example, the second electrode 520 is Ca, Ba, Ca/Al, LiF/Ca, LiF/Al, BaF ₂ /Al, CsF/Al, CaCO ₃ /Al, BaF ₂ /Ca/Al, Al, Mg, It may be Au:Mg or Ag:Mg. For example, the first electrode 510 and the second electrode 520 may be stacked to a thickness of 5 to 300 nm, preferably 10 to 200 nm.

In this embodiment, the first charge transfer layer 540 may be an electron transfer layer supplying electrons to the light emitting material layer 550 . In one exemplary embodiment, the first charge transfer layer 540 includes an electron injection layer 542 positioned adjacent to the first electrode 510 between the first electrode 510 and the light emitting material layer 550 and , An electron transport layer 544 positioned adjacent to the light emitting material layer 550 between the first electrode 510 and the light emitting material layer 550 .

The electron injection layer 542 is made of a material in which fluorine is doped or bonded to a metal such as Al, Cd, Cs, Cu, Ga, Ge, In, or Li, or Al, Mg, In, Li, Ga, Cd, or Cs. , TiO ₂ , ZnO, ZrO, SnO ₂ , WO ₃ , Ta ₂ O ₃ doped or not doped with Cu or the like.

The electron transport layer 544 may be made of an inorganic material and/or an organic material. According to an exemplary embodiment, an inorganic material having excellent charge mobility and a HOMO energy level (or valence band energy level) lower than that of the light emitting material layer 550 is preferably applied to the electron transport layer 544 can do.

When the electron transport layer 544 is made of an inorganic material, the electron transport layer 554 may be a metal oxide doped or undoped with Al, Mg, In, Li, Ga, Cd, Cs, Cu, or the like; semiconductor particles doped or undoped with Al, Mg, In, Li, Ga, Cd, Cs, Cu or the like; and an inorganic material selected from the group consisting of metal nitrides and combinations thereof.

For example, the metal oxide forming the electron transport layer 544 is zinc (Zn), calcium (Ca), magnesium (Mg), titanium (Ti), tin (Sn), tungsten (W), tantalum (Ta), hafnium It may include an oxide of a metal selected from the group consisting of (Hf), aluminum (Al), zirconium (Zr), barium (Ba), and combinations thereof.

More specifically, the metal oxide forming the electron transport layer 544 is titanium oxide (TiO ₂ ), zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), zinc calcium oxide (ZnCaO), zirconium oxide (ZrO ₂ ), tin Oxide (SnO ₂ ), tin magnesium oxide (SnMgO), tungsten oxide (WO ₃ ), tantalum oxide (Ta ₂ O ₃ ), hafnium oxide (HfO ₃ ), aluminum oxide (Al ₂ O ₃ ), barium titanium oxide (BaTiO ₃ ), barium zirconium oxide (BaZrO ₃ ), and combinations thereof, but the present invention is not limited thereto.

Other inorganic materials capable of forming the electron transport layer 544 include semiconductor particles such as CdS, ZnSe, and ZnS doped or undoped with Al, Mg, In, Li, Ga, Cd, Cs, or Cu; It includes an inorganic material selected from the group consisting of nitrides such as Si ₃ N ₄ and combinations thereof.

When the electron transport layer 544 is made of an organic material, the electron transport layer 544 may include an oxazole-based compound, an isoxazole-based compound, a triazole-based compound, an isothiazole-based compound, an oxadiazole-based compound, a thiadiazole-based compound, or perylene. A base compound or an aluminum complex can be used. Specifically, the organic material capable of constituting the electron transport layer 544 may be made of an organic material selected from the group consisting of TAZ, BCP, TPBi, Alq ₃ , Balq, Salq, and combinations thereof, but the present invention is limited thereto It doesn't work.

The first charge transfer layer 540 may be formed of only one layer of the electron transport layer 544 . In addition, the first charge transfer layer 540 may be formed with one layer of the electron transport layer 544 obtained by blending cesium carbonate with the aforementioned inorganic electron transport material. The first charge transfer layer 540 including the electron injection layer 542 and/or the electron transport layer 544 may be formed using a solution process. For example, the electron injection layer 542 and the electron transport layer 544 may be stacked to a thickness of 10 to 200 nm, preferably 10 to 100 nm.

The light emitting material layer 550 may be formed of inorganic light emitting particles or organic light emitting materials. The inorganic light-emitting particles may be nano-inorganic light-emitting particles such as quantum dots or quantum rods. Quantum dots or quantum rods may have a single structure or a heterogeneous core/shell structure. At this time, the shell may be composed of one shell or may be composed of multiple shells. The quantum dot or quantum rod may have a type-I core/shell structure, a type II core/shell structure, or a reverse type-I core/shell structure.

In one exemplary embodiment, the core and the shell may be semiconductor nanocrystals or metal oxide nanocrystals having a quantum confinement effect. For example, semiconductor nanocrystals capable of forming cores and/or shells include group II-VI compound semiconductor nanocrystals of the periodic table, group III-V compound semiconductor nanocrystals of the periodic table, group IV-VI compound semiconductor nanocrystals of the periodic table, and periodic table I -III-VI compound may be selected from the group consisting of semiconductor nanocrystals and combinations thereof.

Specifically, the periodic table II-VI compound semiconductor nanocrystals capable of forming a core and / or a shell are MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe , ZnTe, ZnSeS, ZnTeSe, ZnO, CdS, CdSe, CdTe, CdSeS, CdZnS, CdSeTe, CdO, HgS, HgSe, HgTe, CdZnTe, HgCdTe, HgZnSe, HgZnTe, CdS/ZnS, CdS/ZnSe, CdSe/ZnS, CdSe /ZnSe, ZnSe/ZnS, ZnS/CdSZnS, CdS/CdZnS/ZnS, ZnS/ZnSe/CdSe, and combinations thereof. Group III-V compound semiconductor nanocrystals capable of forming cores and/or shells are AlN, AlP, AlAs, AlSb, GaN, GaP, Ga ₂ O ₃ , GaAs, GaSb, InN, In ₂ O ₃ , InP, InAs, InSb, AlGaAs, InGaAs, InGaP, AlInAs, AlInSb, GaAsN, GaAsP, GaAsSb, AlGaN, AlGaP, InGaN, InAsSb, InGaSb, AlGaInP, AlGaAsP, InGaAsP, InGaAsSb, InAsSbP, AlInAsP, AlGaAsN, InGaAsN, InAlAsN, GaAsSbN, It may be selected from the group consisting of GaInNAsSb and combinations thereof.

Group IV-VI compound semiconductor nanocrystals capable of forming cores and/or shells are TiO ₂ , SnO ₂ , SnS, SnS ₂ , SnTe, PbO, PbO ₂ , PbS, PbSe, PbTe, PbSnTe, and combinations thereof. It can be selected from the constituting group. In addition, the periodic table group I-III-VI compound semiconductor nanocrystals capable of forming a core and/or a shell are AgGaS ₂ , AgGaSe ₂ , AgGaTe 2 , AgInS ₂ , CuInS ₂ , CuInSe _{2 ,} Cu ₂ SnS ₃ , CuGaS ₂ , It may be selected from the group consisting of CuGaSe ₂ and combinations thereof.

Optionally, the core and/or the shell may be formed of compound semiconductor nanocrystals of different groups, such as group III-V compound semiconductor nanocrystals of the periodic table, such as InP/ZnS, InP/ZnSe, and GaP/ZnS, and compound semiconductor nanocrystals of group II-VI compound semiconductor nanocrystals of the periodic table. Crystals may form multiple layers.

In addition, the metal oxide nanocrystals capable of forming the core and/or the shell may be group II or III metal oxide crystals of the periodic table. For example, the metal oxide nanocrystals that can be applied to the core and/or the shell may be selected from the group consisting of MgO, CaO, SrO, BaO, Al ₂ O ₃ and combinations thereof.

If necessary, the semiconductor nanocrystal constituting the core and/or the shell may be doped or undoped with a rare earth element such as Eu, Er, Tb, Tm, Dy or any combination thereof, or Mn, Cu, Ag , transition metal elements such as Al, Mg or any combination thereof.

For example, the core constituting the quantum dot or quantum rod is ZnSe, ZnTe, CdSe, CdTe, InP, ZnCdS, Cu _x In _1-x S, Cu _x In _1-x Se, Ag _x In _1-x S and these It may be selected from the group consisting of a combination of. In addition, the shell constituting the quantum dot or quantum rod is ZnS, GaP, CdS, ZnSe, CdS/ZnS, ZnSe/ZnS, ZnS/ZnSe/CdSe, GaP/ZnS, CdS/CdZnS/ZnS, ZnS/CdSZnS, Cd _X Zn It may be selected from the group consisting of _1-x S and combinations thereof.

On the other hand, quantum dots or quantum rods are alloy quantum dots/quantum rods such as homogeneous alloy quantum dots/quantum rods or gradient alloy quantum dots/quantum rods (alloy QDs/alloy QRs; for example, CdS _x Se _{1- x} , CdSe _x Te _1-x , Zn _x Cd _1-x Se).

In one exemplary embodiment, the light-emitting material layer 550 is coated on the first charge transfer layer 540 through a solution process of coating a dispersion containing quantum dots or quantum rods, which are light-emitting nanoparticles, in a solvent, and the solvent. It can be formed by volatilizing. As a method of forming the light emitting material layer 550, solution processes such as spin coating, drop coating, dip coating, spray coating, roll coating, flow coating, casting, screen printing, or inkjet printing may be used alone or in combination.

When the light emitting material layer 550 is made of an organic light emitting material, the light emitting material layer 550 may be made of an organic light emitting material that emits red, green and/or blue light, and may include a fluorescent material or a phosphorescent material. In addition, the organic light emitting material constituting the light emitting material layer 550 may include a host and a dopant. When the organic light emitting material is composed of a host-dopant system, the dopant may be doped in an amount of 1 to 50% by weight, preferably 1 to 30% by weight, based on the weight of the host, but the present invention is not limited thereto. If necessary, when the light emitting material layer 550 is made of an organic light emitting material, the light emitting material layer 550 may include a delayed light emitting material.

When the light emitting material layer 550 is made of an organic light emitting material, the light emitting material layer 250 may be formed by a vacuum deposition process including vacuum vapor deposition or sputtering, spin coating, drop coating, dip coating, spray coating, roll coating, In addition to flow coating, a solution process such as a casting process, screen printing, or inkjet printing may be used alone or in combination. For example, the light emitting material layer 550 may be formed to a thickness of 5 to 300 nm, preferably 10 to 200 nm, but the present invention is not limited thereto.

Meanwhile, in the third embodiment of the present invention, the second charge transfer layer 560 may be a hole transfer layer supplying holes to the light emitting material layer 550 . In one exemplary embodiment, the second charge transfer layer 560 includes a hole injection layer 562 positioned adjacent to the second electrode 520 between the second electrode 520 and the light emitting material layer 550 and , and a hole transport layer 564 positioned adjacent to the light emitting material layer 550 between the second electrode 520 and the light emitting material layer 550 .

The hole injection layer 562 is PEDOT:PSS, TDATA doped with F4-TCNQ, for example, p-doped phthalocyanine such as ZnPc doped with F4-TCNQ, α-NPD doped with F4-TCNQ, and HAT-CN. And it may be made of a material selected from the group consisting of combinations thereof, but the present invention is not limited thereto. For example, a dopant such as F4-TCNQ may be doped in an amount of 1 to 30% by weight with respect to the host. The hole injection layer 562 may be omitted depending on the structure and shape of the light emitting diode 500 .

The hole transport layer 564 transfers holes from the second electrode 520 to the light emitting material layer 550 . The hole transport layer 564 may be made of an inorganic or organic material.

For example, when the hole transport layer 564 is made of an organic material, the hole transport layer 564 may include 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds such as CBP and CBDP; Aromatic amine selected from the group consisting of NPB (NPD), TPD, spiro-TPD, DNTPD, TCTA, TPB, m-MTDAT), TFB, poly-TPD, spiro-NPB) and combinations thereof or aryl amines which are polynuclear aromatic amines; conductive polymers such as polyaniline, polypyrrole, and PEDOT:PSS; PVK and its derivatives, poly(para)phenylenevinylene and its derivatives such as MEH-PPV and MOMO-PPV , polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly( spiro-fluorene) and its derivatives; metal complexes such as CuPc; And it may be made of an organic material selected from the group consisting of combinations thereof.

When the hole transport layer 564 is made of an inorganic material, the hole transport layer 564 is made of a metal oxide such as NiO, MoO ₃ , Cr ₂ O ₃ , Bi ₂ O ₃ or p-type ZnO, copper thiocyanate (CuSCN), Mo ₂ It may be made of an inorganic material selected from the group consisting of non-oxide metal materials such as S and p-type GaN and/or combinations thereof.

6, the second charge transfer layer 560, which may be a hole transfer layer, is divided into a hole injection layer 562 and a hole transport layer 564. Alternatively, the second charge transfer layer 560 may be formed of a single layer. For example, the second charge transfer layer 560 may be formed of only the hole transport layer 564 without the hole injection layer 562, and a hole injection material (for example, PEDOT:PSS) may be doped with the hole transport organic material described above. may be done.

The second charge transfer layer 560 including the hole injection layer 562 and the hole transport layer 564 may be formed by a vacuum deposition process such as vacuum vapor deposition or sputtering, spin coating, drop coating, A solution process such as dip coating, spray coating, roll coating, flow coating, casting process, screen printing or inkjet printing may be formed alone or in combination. . For example, the hole injection layer 562 and the hole transport layer 564 may each have a thickness of 10 nm to 200 nm, preferably 10 nm to 100 nm, but the present invention is not limited thereto.

In an alternative embodiment, the light emitting diode 500 includes an electron blocking layer (EBL) and/or a light emitting material layer 550 capable of controlling or preventing the movement of electrons between the hole transport layer 564 and the light emitting material layer 550. ) and the electron transport layer 544, at least one exciton blocking layer such as a hole blocking layer (HBL) capable of controlling or preventing the movement of holes may be further included.

Meanwhile, according to the third exemplary embodiment of the present invention, the charge control layer 570 is positioned between the first electrode 510 and the first charge transfer layer 542 . When the electron injection layer 542 is omitted, the charge control layer 570 may be positioned between the first electrode 510 and the electron transport layer 544 .

The charge control layer 570 may include a first material that is a conductive polymer and a second material that has a wide energy band gap. For example, the first material, which is a conductive polymer, is polyphenylene, polyphenylenevinylene, polyphenylene sulfide, poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, polythiophene. , polyacetylene, and combinations thereof. The second material having a wide energy band gap may be selected from the group consisting of cured siloxanes, (meth)acrylate-based polymers, vinyl alcohol-based polymers, and combinations thereof. For example, the cured siloxane may be synthesized from a silane monomer represented by Formula 1, a silane monomer in which at least three C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms, eg, four C ₁ to C ₁₀ alkoxy groups. It can be synthesized from silane monomers in which groups are bonded to silicon atoms.

Since the charge control layer 570 includes a first material that is a conductive polymer, it is possible to prevent charge trapping in which electrons are accumulated in the electron transport layer 564 due to internal defects of the electron transport layer 564 . In addition, the charge control layer 570 including a second material having a wide energy bandgap may function as an energy barrier related to electron injection. 7 is a diagram showing energy levels between an electrode constituting a light emitting diode according to a third exemplary embodiment of the present invention and a light emitting layer.

As shown in FIG. 7, the energy band gap (Eg CCL ), which is the difference between the LUMO energy level and _the HOMO energy level of the charge control layer (CCL) including the second material having a wide energy band gap, is the electron transport layer (ETL) It may be wider than the energy band gap (Eg _ETL ), which is the difference between the conduction band energy level and the valence band energy level of . In one exemplary embodiment, the HOMO energy level (HOMO _CCL ) of the charge control layer (CCL) having the second material having a wide energy bandgap is an electron transport layer (ETL) made of an inorganic material, for example, a metal oxide. It may be lower than the self-band energy level (VB _ETL ) (deep). In addition, the LUMO energy level (LUMOCCL) of the charge control layer (CCL) may be higher than the conduction band energy level (CB _ETL ) of the electron transport layer (ETL) made of a metal oxide (shallow).

Accordingly, the amount of electrons (ⓔ ^- ) supplied from the first electrode to the electron transport layer (ETL) may be reduced or the supply speed of electrons (ⓔ ^- ) may be slowed down. Accordingly, holes supplied from the first electrode 510 to the light emitting material layer 550 (EML) via the electron transport layer 544 (ETL), and the hole transfer layer 560 (HIL/HTL) from the second electrode 520 ), electrons supplied to the light emitting material layer 550 may be injected in a balanced manner. As a result, by preventing charge capture of electrons due to excessively accumulated electrons and preventing electrons excessively injected into the light emitting material layer 550 from recombination, the light emitting efficiency of the light emitting diode 500 is improved and consumption power can be reduced.

In the third embodiment described above, the charge control layer 570 is positioned between the first electrode 510 and the first charge transfer layer 540 . Alternatively, the charge control layer may be positioned between the light emitting material layer and the first charge transfer layer. 8 is a schematic cross-sectional view of a light emitting diode according to a fourth exemplary embodiment of the present invention, showing the light emitting diode having an inverted structure.

As shown in FIG. 8, the light emitting diode 600 according to the fourth exemplary embodiment of the present invention includes a first electrode 610, a second electrode 620 facing the first electrode 610, a first The light emitting layer 630 including the light emitting material layer 650 positioned between the electrode 610 and the second electrode 620 is included. The light emitting layer 630 includes a first charge transfer layer 640 positioned between the first electrode 610 and the light emitting material layer 650 and a second positioned between the second electrode 620 and the light emitting material layer 650. A second charge transfer layer 660 and a charge control layer 670 positioned between the light emitting material layer 650 and the first charge transfer layer 640 are included.

In the fourth embodiment of the present invention, the first electrode 610 may be an electron injection electrode, and the second electrode 620 may be a hole injection electrode. The first charge transfer layer 640 may be an electron transfer layer and may include an electron injection layer 642 and an electron transport layer 640 . The light-emitting material layer 650 may be formed of inorganic light-emitting particles such as quantum dots or quantum rods, or may be formed of organic light-emitting materials such as a host and a dopant. The second charge transfer layer 660 may be a hole transfer layer and may include a hole injection layer 662 and a hole transport layer 664 .

In an alternative embodiment, the light emitting diode 600 includes an electron blocking layer (not shown) and/or a light emitting material layer capable of controlling and preventing the movement of electrons between the hole transport layer 664 and the light emitting material layer 650. At least one exciton blocking layer such as a hole blocking layer (not shown) capable of controlling or preventing the movement of holes may be further included between 650 and the electron transport layer 644 .

Since these configurations are substantially the same as those described in the third embodiment of the present invention, detailed descriptions are omitted.

In the fourth embodiment of the present invention, the charge control layer 670 is located between the light emitting material layer 650 and the first charge transfer layer 640, for example, the electron transport layer 644. As in the third embodiment, the charge control layer 670 may be formed of a first material that is a conductive polymer and a second material that has a wide energy band gap.

For example, the first material, which is a conductive polymer, is polyphenylene, polyphenylenevinylene, polyphenylene sulfide, poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, polythiophene. , polyacetylene, and combinations thereof. The second material having a wide energy band gap may be selected from the group consisting of cured siloxanes, (meth)acrylate-based polymers, vinyl alcohol-based polymers, and combinations thereof. For example, the cured siloxane may be synthesized from a silane monomer represented by Formula 1, a silane monomer in which at least three C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms, eg, four C ₁ to C ₁₀ alkoxy groups. It can be synthesized from silane monomers in which groups are bonded to silicon atoms.

Since the charge control layer 670 includes a first material that is a conductive polymer, it is possible to prevent charge trapping in which electrons are accumulated in the electron transport layer 644 due to internal defects of the electron transport layer 644 . In addition, the charge control layer 670 including a second material having a wide energy bandgap may function as an energy barrier related to electron injection.

Accordingly, holes supplied from the second electrode 620 to the light emitting material layer 650 via the second charge transfer layer 660 pass through the first electrode 610 via the first charge transfer layer 640. Thus, electrons supplied to the light emitting material layer 650 can be injected in a balanced manner. As a result, by preventing charge trapping of electrons due to excessively accumulated electrons and preventing electrons excessively injected into the light emitting material layer 650 from recombination, the light emitting efficiency of the light emitting diode 600 is improved and consumption power can be reduced.

Hereinafter, the present invention will be described through exemplary embodiments, but the present invention is not limited to the technical idea described in the following examples.

Example 1: Manufacturing of single electronic device including charge control layer

An electron-only device formed in the order of the light emitting material layer-charge control layer-electron transport layer was manufactured as follows. A light emitting material layer (EML; thickness: 15 nm) was formed by spin coating (3000 rpm) red quantum dots (InP/ZnSe) dispersed in an octane solvent on an ITO-coated glass substrate as a lower electrode. 1 mL of a stock solution in which 0.1 mL of tetraethylorthosilicate (TEOS) is dispersed in 0.9 mL of isopropyl alcohol (IPA) on the top of the light emitting material layer, and 0.05 mL of PEDOT:PSS based on deionized water (DI) A solution containing PEDOT:PSS and TEOS at a volume ratio of 1:2 was spin-coated (4000 rpm, 4 seconds), and dried (80°C, 15 minutes) to form a charge control layer (a combination of cured TEOS and PEDOT). thickness of 1 to 5 nm) was formed. On the charge control layer, ZnMgO dispersed in ethanol was spin-coated (1000 rpm, 45 seconds) to form an electron transport layer (30 nm in thickness). An electron only device (EOD) was manufactured by laminating an Al electrode (80 nm in thickness) as an upper electrode on the hole transport layer through a deposition process.

Example 2: Manufacturing of single electronic device including charge control layer

An electron transport layer made of ZnMgO is first formed on the top of the light emitting material layer, and a storage solution in which 0.1 mL of TEOS is dispersed in 0.9 mL of IPA and 0.05 mL of PEDOT:PSS based on deionized water (PEDOT:PSS and TEOS 1: The procedure of Example 1 was repeated except that the charge control layer was formed by spin-coating a solution mixed with a volume ratio of 2) to prepare an electron-only device having a light emitting material layer-electron transport layer-charge control layer structure. .

Comparative Example 1: Preparation of an electron-only device consisting of only an electron transport layer

An electron-only device having a light-emitting material layer-electron transport layer structure was manufactured by repeating the procedure of Example 1 except that only the electron transport layer made of ZnMgO was formed on the light emitting material layer and the charge control layer was not formed.

Experimental Example 1: Evaluation of electrical and optical characteristics of a single electronic device

Electrical and optical characteristics of the single electronic device prepared in Examples 1 and 2 and Comparative Example 1 were evaluated. For comparison, a device (hereinafter referred to as a QD device) in which a light emitting material layer made of red quantum dots (InP/ZnSe) and an upper electrode were sequentially formed on a glass substrate coated with ITO as a lower electrode was used. Each device was analyzed using a fluorescence lifetime spectrometer (Time Correlated Single Photon Counting Spectrometer; TCSPC).

9 shows the photoluminescence (PL) intensity measurement results measured in the single electronic device according to this experimental example. Compared to the device consisting of only the QD light-emitting material layer, in the case of the electron-only device (Comparative Example 1) further formed with an electron transport layer, the PL intensity was reduced to a level of 10%. On the other hand, when a charge control layer was introduced between the light emitting material layer and the electron transport layer, the PL intensity was recovered to 50% compared to the device consisting of only the light emitting material layer (Example 1), and the charge control layer between the electron transport layer and the upper electrode In the case of introducing the layer, it was confirmed that the PL intensity was recovered to a level of 75% compared to the device consisting only of the light emitting material layer (Example 2). These results suggest that by introducing the charge control layer adjacent to the electron transport layer, accumulation of electrons due to internal defects in the electron transport layer can be prevented, and the charging trap of electrons is suppressed, thereby emitting intensity of the adjacent light emitting material layer. It is interpreted as preventing the degradation of

The electron transfer rate (K _ET ) was evaluated using the same electron-only device. In each device, the decay time of electron emission intensity and the lifetime of electrons (τ) were measured, and the electron transport rate was measured according to the following formula. The measurement results are shown in Table 1 and FIG. 10 below. Compared to the electron-only device of Comparative Example 1 comprising only the electron transport layer, the electron transfer rate of the electron-only device of Examples 1 and 2 having the charge control layer was slow. In the case of the electron-only device of Comparative Example 1 including only the electron transport layer, electrons are accumulated in the electron transport layer due to an internal defect in electron transport, and electrons are charged in the electron transport layer. On the other hand, in the case of the electron-only devices of Examples 1 and 2, the charge control layer formed adjacent to the electron transport layer prevents defects inside the electron transport layer and prevents charge capture of electrons, which is interpreted as slowing down the electron transfer rate. .

Electrical Characteristics of Single Electronic Device Sample Decay Time (ns) τ ₁ τ ₂ τ _{3 KET} QD 35.4 16.8 39.2 188.8 - Comparative Example 1 18.8 7.03 18.98 84.64 0.025 Example 1 26.5 9.48 25.29 103.45 0.009 Example 2 30.6 11.37 27.65 121.51 0.004

Examples 3 to 4: Fabrication of a single electronic device including a charge control layer

To form a charge control layer on top of the electron transport layer, 1 mL of a stock solution in which 0.1 mL of TEOS is dispersed in 0.9 mL of IPA and 0.03 mL of deionized water-based PEDOT:PSS (volume ratio of PEDOT:PSS and TEOS 3:10) Using a mixed solution of (Example 3), 1 mL of a stock solution in which 0.1 mL of TEOS is dispersed in 0.9 mL of IPA and 0.04 mL of PEDOT:PSS based on deionized water (PEDOT:PSS and TEOS are in a volume ratio of 4:10) The procedure of Example 2 was repeated except that the mixed solution of (Example 4) was used to prepare an electron-only device having a light emitting material layer-electron transport layer-charge control layer structure.

Comparative Examples 2 to 5: Preparation of single electronic device including charge control layer

In order to form a charge control layer on top of the electron transport layer, 1 mL of a stock solution in which 01 mL of TEOS is dispersed in 0.9 mL of IPA and 0.01 mL of deionized water-based PEDOT:PSS (PEDOT:PSS and TEOS have a volume ratio of 1:10) ) using a mixed solution (Comparative Example 2), 1 mL of a stock solution in which 0.1 mL of TEOS is dispersed in 0.9 mL of IPA, and 0.1 mL of PEDOT: PSS based on deionized water (PEDOT: PSS and TEOS are at a volume ratio of 1: 1) ) using a mixed solution (Comparative Example 3), 1 mL of a stock solution in which 0.1 mL of TEOS is dispersed in 0.9 mL of IPA, and 0.5 mL of PEDOT: PSS based on deionized water (PEDOT: PSS and TEOS are at a volume ratio of 5: 1) ) using a mixed solution (Comparative Example 3), 1 mL of a stock solution in which 0.1 mL of TEOS is dispersed in 0.9 mL of IPA, and 0.02 mL of PEDOT: PSS based on deionized water (PEDOT: PSS and TEOS are at a volume ratio of 2:10 ), except that a mixed solution of (Comparative Example 4) was used, the procedure of Example 2 was repeated to manufacture an electron-only device having a light emitting material layer-electron transport layer-charge control layer structure.

Experimental Example 2: Evaluation of electrical and optical characteristics of a single electronic device

Electrical and optical characteristics of the single electronic devices prepared in Examples 2 to 4 and Comparative Examples 2 to 5, respectively, were evaluated. A QD device was used for comparison. First, the sheet resistance of the charge control layer used in Examples 2 to 4 and Comparative Examples 2 to 5 was measured. The measurement results are shown in Table 2 and FIG. 11 below.

Sheet resistance of the charge control layer Sample PEDOT/PSS volume ratio cotton resistance Example 2 1:2 ~ 2 ㏁/sq Example 3 3:10 ~ 7 ㏁/sq Example 4 4:10 ~ 4 ㏁/sq Comparative Example 2 1:10 ~ 50 ㏁/sq Comparative Example 3 1:1 ~ 500 kΩ/sq Comparative Example 4 5:1 ~ 10 kΩ/sq Comparative Example 5 2:10 ~ 12 ㏁/sq

As shown in Table 2 and FIG. 11, when the charge control layer is formed, when the volume ratio of PEDOT: PSS and TEOS is 3:10 to 1:2 (Examples 2 to 4) Static electricity due to electronic charge It is sufficient to discharge and has an appropriate sheet resistance to prevent leakage current. On the other hand, when the volume ratio of PEDOT:PSS and TEOS is less than 3:10 (Comparative Example 2 and Comparative Example 5), the content of the conductive polymer included in the charge control layer is too small to discharge static electricity caused by electron charge. High sheet resistance is measured. In addition, when the volume ratio of PEDOT:PSS and TEOS exceeds 1:2 (Comparative Example 2 and Comparative Example 4), the content of the conductive polymer included in the charge control layer is excessively increased, causing leakage current. When such a charge control layer is used in a light emitting diode, the current before the driving voltage (Turn on) becomes excessively high, and device performance may deteriorate (result not shown).

Subsequently, TCSPC analysis was performed on the single electronic devices prepared in Examples 2 to 3 and Comparative Examples 1 to 5 in the same manner as in Experimental Example 1. 12 shows the PL intensity measurement results measured in the single electronic device according to this experimental example. In the case of the electron-only device in which the charge control layer was introduced between the electron transport layer and the upper electrode, the PL intensity was recovered to 88% compared to the device composed of only the light emitting material layer (see Example 4). On the other hand, the PL intensity of the electron-only device introduced with the charge control layer having a low PEDOT content was slightly increased compared to the electron-only device composed of only the electron transport layer.

In addition, the electron transfer rate was evaluated according to the same procedure as in Experimental Example 1. The evaluation results are shown in Table 3 and FIG. 13 below. Compared to the electron-only device of Comparative Example 1 comprising only the electron transport layer, the electron transfer rate of the electron-only device of Examples 2 and 5 having the charge control layer was greatly reduced. It is interpreted that the charge control layer introduced into the electron-only devices of Examples 2 and 4 prevents defects inside the electron transport layer and prevents charge capture of electrons, thereby slowing down the electron transfer rate.

Electrical Characteristics of Single Electronic Device Sample Decay Time (ns) τ ₁ τ ₂ τ _{3 KET} QD 35.4 16.8 39.2 188.8 - Comparative Example 1 18.8 7.03 18.98 84.64 0.025 Example 4 33.4 13.85 34.10 147.37 0.0017 Example 2 30.6 11.37 27.65 121.51 0.004 Example 3 26.7 10.70 25.44 109.12 0.009 Comparative Example 4 21.1 9.30 20.87 93.2 0.019

Experimental Example 3: Evaluation of surface morphology

The thin film flatness before depositing the upper electrode in the single electronic device manufactured in Example 2 and Comparative Example 1 was evaluated using AFM. For comparison, the thin film flatness of the QD device was evaluated. The evaluation results are shown in Table 4 and FIGS. 14 to 16 below. It was confirmed that the flatness of the thin film was greatly improved by introducing the charge control layer thin film.

surface roughness (nm) Sample 1 time Episode 2 average QD 11.0 14.2 12.6 Comparative Example 1 11.2 13.4 12.3 Example 2 5.2 3.6 4.4

Example 4: Manufacturing of Light-Emitting Diodes

A light emitting diode was manufactured in which a charge control layer containing a cured TEOS material and PEDOT:PSS was introduced between the electron transport layer and the upper electrode. After patterning the light emitting area of ITO glass to be 3 mm X 3 mm in size, it was cleaned. Subsequently, a light emitting layer and a cathode were sequentially formed in the following order.

Hole injection layer (HIL; PEDOT:PSS, after spin coating at 5000 rpm for 60 seconds (water base), drying at 200 ° C for 15 minutes, 20 nm), hole transport layer (HTL; PVK, spin coating for 45 seconds at 4000 rpm) Back (in toluene), drying for 30 minutes at 170 ° C, 20 nm), light emitting material layer (EML; red quantum dot (InP / ZnSe); spin coating for 45 seconds at 3000 rpm (in octane); 15 nm), electron transport layer ( ETL; ZnMgO, 45 sec spin coating at 1000 rpm (in ethanol, 30 nm), charge control layer (2:1 mixture of TEOS dispersed in IPZ and PEDOT:PSS) spin coating at 4000 rpm for 45 sec and then dried at 80 °C for 15 minutes; 1-5 nm). Cathode (Al, deposited after transferring the substrate on which the light emitting layer is formed to a vacuum chamber (1X110-6 Torr), 80 nm)

After deposition, it was moved from the deposition chamber to a dry box for film formation and subsequently encapsulated using UV curing epoxy and a moisture getter. This light emitting diode has an emission area of 9 mm 2 .

Comparative Example 6: Manufacturing of light emitting diode without charge control layer

A light emitting diode was manufactured by repeating the procedure of Example 1 except that the charge control layer was not formed.

Experimental Example 4: Evaluation of Physical Properties of Light-Emitting Diodes

The light emitting diodes manufactured in Example 5 and Comparative Example 6 were connected to an external power supply source, and the EL characteristics of all devices manufactured in the present invention were evaluated at room temperature using a constant current supply source (KEITHLEY) and a photometer PR 650. . Specifically, under the condition of a current density of 10.00 mA/cm 2 , the external quantum efficiency (EQE), luminance (cd/m 2 ), and emission peak wavelength ( wavelength peak, W _p ), full-width at half maximum (FWHM) and luminescence lifetime were measured, respectively. Table 5 and FIG. 17 show the measurement results.

Light emitting diode properties Sample EQE cd/㎡ W _p FWHM Comparative Example 6 4.29 283 638 52 Example 5 5.80 409 640 52

As shown in Table 5, the light emitting efficiency of the light emitting diode to which the charge control layer was introduced according to the present invention was improved. Specifically, compared to the light emitting diode of Comparative Example 6 consisting of only the electron transport layer, the light emitting diode of Example 5 in which the charge control layer was introduced improved quantum efficiency and luminance by 35.2% and 44.5%, respectively, and the light emitting lifetime was greatly improved. . On the other hand, even if the charge control layer was introduced into the light emitting diode, it was confirmed that the intended light emission could be realized because there was little effect on the emission peak wavelength and half width. Therefore, by forming a charge control layer on one surface of the electron transport layer, a light emitting diode with significantly improved light emitting efficiency can be implemented, which can be applied to a light emitting device.

In the above, the present invention has been described based on exemplary embodiments and examples of the present invention, but the present invention is not limited to the technical idea described in the above embodiments and examples. Rather, those skilled in the art to which the present invention belongs can easily make various modifications and changes based on the above-described embodiments and examples. However, it is clear from the appended claims that all such modifications and changes fall within the scope of the present invention.

100: light emitting diode display
200, 300, 400, 500, 600: light emitting diode
210, 310, 410, 510, 610: first electrode
230. 330, 430, 530, 630: light emitting layer (light emitting unit)
340, 440, 540, 640: first charge transfer layer
342, 442, 562, 662: hole injection layer
344, 444, 564, 664: hole transport layer
350, 450, 550, 650: light emitting material layer
360, 460, 560, 660: second charge transfer layer
362, 462, 542, 642: electron injection layer
364, 464, 544, 644: electron transport layer
370, 470, 570, 670: charge control layer

Claims (20)

a first electrode and a second electrode facing each other;
a light emitting material layer positioned between the first electrode and the second electrode; and
A charge control layer positioned between the light emitting material layer and the first electrode or the second electrode,
The charge control layer includes a first material that is a conductive polymer;
A light emitting diode comprising a second material selected from the group consisting of cured siloxanes, (meth)acrylate-based polymers, vinyl alcohol-based polymers, and combinations thereof.
According to claim 1,
The conductive polymer is polyphenylene, polyphenylene vinylene, polyphenylene sulfide, poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), polyaniline, polypyrrole, polythiophene, polyacetylene, and combinations thereof. A light emitting diode selected from the group consisting of.
According to claim 1,
The cured siloxane is a light emitting diode synthesized from a silane monomer represented by Formula 1 below.
[Formula 1]

In Formula 1, R ₁ and R ₂ are each independently hydrogen, deuterium, tritium, a hydroxy group, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₂ ~ C ₁₀ alkenyl group, C ₁ ~ C ₁₀ alkoxy group , C ₁ ~ C ₁₀ alkyl amino group, C ₁ ~ C ₁₀ alkyl acryloxy group, C ₁ ~ C ₁₀ alkyl methacryloxy group, thiol group, C ₁ ~ C ₁₀ alkyl thiol group, epoxy group, C ₁ ~ C ₁₀ alkyl Epoxy group, C ₅ ~ C ₂₀ cycloalkyl epoxy group, C ₄ ~ C ₂₀ heteroaryl epoxy group, glycidyloxy group, C ₁ ~ C ₁₀ alkyl glycidyloxy group, unsubstituted or halogen atom-substituted C ₅ ~ C ₂₀ aryl group , C ₄ ~ C ₂₀ heteroaryl group, C ₅ ~ C ₂₀ aryloxy group, C ₄ ~ C ₂₀ heteroaryloxy group, C ₅ ~ C ₂₀ aryl amino group and C ₅ ~ C ₂₀ hetero group, unsubstituted or substituted with a halogen atom selected from the group consisting of aryl amino groups; R ₃ and R ₄ are each independently hydrogen, deuterium, tritium, C ₁ ~ C ₁₀ linear or branched alkyl group, C ₁ ~ C ₁₀ alkyl amino group, unsubstituted or halogen atom-substituted C ₅ ~ C ₂₀ aryl group, Selected from the group consisting of an unsubstituted or halogen atom-substituted C ₅ ~C ₂₀ heteroaryl group, a C ₅ ~C ₂₀ aryl amino group, and a C ₅ ~C ₂₀ heteroaryl amino group.
According to claim 1,
The cured siloxane is a light emitting diode synthesized from a silane monomer in which at least three C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms.
According to claim 1,
The cured siloxane is a light emitting diode synthesized from a silane monomer in which four C ₁ to C ₁₀ alkoxy groups are bonded to silicon atoms.
According to claim 1,
The charge control layer is formed to a thickness of 1 to 10 nm light emitting diode.
According to claim 1,
The second material is a cured siloxane, and the charge control layer is a light emitting diode in which the first material and the cured siloxane are mixed in a volume ratio of 3:10 to 1:2.
According to claim 1,
The sheet resistance of the charge control layer is 1 MΩ / sq or more and 10 MΩ / sq or less.
According to claim 1,
The charge control layer is positioned between an electrode functioning as a cathode among the first electrode and the second electrode.
According to claim 9,
The light emitting diode further comprises an electron transfer layer positioned between the light emitting material layer and the charge control layer or positioned between the charge control layer and the cathode.
According to claim 10,
The light emitting diode further comprising a hole transfer layer positioned on the opposite side of the electron transfer layer with the light emitting material layer as a center.
According to claim 10,
The electron transport layer is a light emitting diode comprising an electron transport layer made of an inorganic material.
According to claim 12,
The energy band gap (Eg _CCL ) between the highest occupied molecular orbital energy level (HOMO _CCL ) and the lowest unoccupied molecular orbital energy level (LUMO _CCL ) of the charge control layer is the valence band energy level (VB of the electron transport layer). _ETL ) and conduction band energy levels (CB _ETL ) of a light emitting diode larger than the energy bandgap (Eg _ETL ).
According to claim 12,
A light emitting diode wherein a highest occupied molecular orbital energy level (HOMO _CCL ) of the charge control layer is lower than a valence band energy level (VB _ETL ) of the electron transport layer.
According to claim 12,
A light emitting diode wherein a lowest unoccupied molecular orbital energy level (LUMO _CCL ) of the charge control layer is higher than a conduction band energy level (CB _ETL ) of the electron transport layer. According to claim 12,
The inorganic material of the electron transport layer includes a metal oxide.
According to claim 16,
The metal oxide is zinc (Zn), calcium (Ca), magnesium (Mg), titanium (Ti), tin (Sn), tungsten (W), tantalum (Ta), hafnium (Hf), aluminum (Al), zirconium A light emitting diode comprising an oxide of a metal selected from the group consisting of (Zr), barium (Ba), and combinations thereof.
According to claim 1,
The light emitting material layer includes inorganic light emitting particles.
According to claim 18,
The inorganic light-emitting particles include a light-emitting diode including quantum dots (QDs) or quantum rods (QRs).
Board; and
A light emitting device disposed on the substrate and including a light emitting diode according to any one of claims 1 to 19.

Images