KR20150107249A - A light-emitting diode with single layer quantum dot using polymer surface modification layer - Google Patents

Abstract

The present invention relates to a light emitting diode with a quantum dot signal layer using a polymer surface reforming layer, and more specifically, to a light emitting diode with a quantum dot single layer using a polymer surface reforming layer, which is organized to form the quantum dot single layer by the interaction between a surface dipole of an amine group contained in the reforming layer using polyethylenimine ethoxylated (PEIE), which is a polymer, on a transparent electrode as a surface reforming layer. The structure of the light emitting diode is converted into an inverted structure by extremely substituting a negative electrode for the transparent electrode, thereby enabling excellent color realization and a life extension.

Description

[0001] The present invention relates to a quantum dot light-emitting diode (OLED) using a polymer surface modification layer,

The present invention relates to a quantum dot single layer light emitting diode using a polymer surface modification layer, and more particularly to a quantum dot single layer light emitting diode using a polymer surface modification layer, The structure of a single layer of quantum dots due to the interaction of the surface dipole of the amine group with the quantum dots enables the conversion of the structure of the transparent electrode to the cathode, And a quantum dot single layer light emitting diode using the surface modification layer.

Display, which is at the center of the world industry, is becoming increasingly important as a video delivery medium. In order to further develop in the future, it has to meet the requirements of low power consumption, light weight, and high image quality. In order to meet these requirements, quantum luminescent devices have been studied variously in recent years. Such a quantum luminescent device is advantageous in that it can be slimmed, has a higher color purity than other organic displays, and can be driven for a long time.

Quantum dots (QDs) are semiconductor nanoparticles. Quantum dots of nanometer size emit as electrons staying in the valence band come down to the conduction band. The smaller the particle size, the shorter the wavelength, and the larger the particle size, the longer the wavelength. Thus, quantum dots have unique electrical and optical properties that differ from conventional semiconductor materials. Therefore, by adjusting the size of the quantum dots, quantum dots can be formed to emit light of a desired wavelength band, and various colors can be simultaneously realized.

Conventional organic light emitting devices use an organic material as a material of the light emitting layer, and an organic light emitting diode (OLED) using the organic light emitting device can realize a single color such as blue, red, and green depending on the type of device. There is a limit to expressing light.

On the other hand, light emitting diodes fabricated using quantum dots have higher color rendering power than organic light emitting diodes, and can be driven at a low power for a long time.

On the other hand, in order to increase the efficiency of a quantum dot light-emitting diode, a technique for forming a single quantum dot light-emitting layer is required.

As a conventional technique, there has been proposed a technique for fabricating an organic solar cell having an inverted structure by lowering the work function of ITO (Indium Tin Oxide) by using PEIE (Polysilylimine ethoxylated) [Yinhua Zhou et al, A universal Method to Produce Low-Work Function Electrodes for Organic Electronics Science 336, 327-332 (2012)].

However, this does not provide any technical solution to the fabrication of light emitting diodes having a single layer of quantum dots as a general technique for inverted solar cells using a transparent electrode as a cathode.

In addition, a technique for fabricating a quantum dot light-emitting diode having a conventional structure by depositing a multi-layer multi-layer using a quantum dot having a light emitting region of 620 nm has been proposed (JM Caruge et al., Colloidal quantum- dot light-emitting diodes with metal-oxide charge transport layers, Nature Photonics 2 , 247-250 (2008)]. Here, a quantum dot light emitting diode having a multilayered light emitting layer having characteristics of structure (a) and energy band diagram (b) as shown in FIG. 1 is provided.

However, since the quantum dot luminescent layer is composed of a plurality of luminescent layers, recombination of holes and electrons generated in the anode and the cathode is dispersed in the multilayer luminescent layer, resulting in poor efficiency in chromaticity expression. Thus, a light emitting diode having a single quantum dot is fabricated No technical attempts are suggested at all.

Korean Patent Laid-Open Publication No. 2010-0095527 discloses an inverted OLED device having improved efficiency. In this method, ITO is deposited on a glass substrate to be used as an anode, each organic layer is deposited, and a metal electrode is used as a cathode. In the conventional organic light emitting diode (OLED) structure of the present invention, only the upper and lower structures are substituted for the organic light emitting diode. However, since the organic light emitting diode is not inverted, There is a limit to the luminous efficiency and there is no suggestion to provide or manufacture a light emitting diode having a quantum dot as a single layer at all.

1. Korean Patent Publication No. 2010-0095527

1. Yinhua Zhou et al., A universal Method to Produce Low-Work Function Electrodes for Organic Electronics Science 336, 327-332 (2012). 2. J. M. Caruge et al., Colloidal quantum-dot light-emitting diodes with metal-oxide charge transport layers, Nature Photonics 2, 247-250 (2008).

As a result of long research to solve the problems of the prior art as described above, it has been found that a single layer of a quantum dot can be formed by a simple spin coating solution process using a polymeric PEIE (surface modification layer) The work function is lowered to a structure in which the cathode is extensively changed to realize a superior color and an extended lifetime. Thus, the present invention has been completed.

Accordingly, an object of the present invention is to provide a quantum dot single layer light emitting diode using a polymer surface modification layer.

Another object of the present invention is to provide a quantum dot single-layer light-emitting diode capable of realizing excellent color and prolonging the life.

Still another object of the present invention is to provide a method of manufacturing a quantum dot single layer light emitting diode by a simple method using a polymer surface modification layer.

In order to solve the above-mentioned problems, the present invention provides a method for fabricating a semiconductor device, which comprises stacking a polymer surface modification layer made of PEIE (Polyehthylenimine ethoxylated) on a transparent electrode layer laminated on a substrate, a single quantum dot layer laminated on the polymer surface modification layer, And a hole transporting layer formed on the hole transporting layer. The present invention also provides a quantum dot single layer light emitting diode using the polymer surface modification layer.

According to another aspect of the present invention, Forming a polymer surface modification layer on the transparent electrode layer by PEIE (Polyehthylenimine ethoxylated); Forming a single quantum dot layer by coating the polymer surface modification layer with a quantum dot colloid solution; And forming a hole transport layer by coating the light emitting material on the single quantum dot single layer. The present invention also provides a method of manufacturing a quantum dot single layer light emitting diode using the polymer surface modification layer,

The quantum dot single layer light emitting diode using the polymer surface modification layer according to the present invention can form a single quantum dot layer by a simple spin coating solution process.

In addition, by applying the PEIE surface modification layer, quantum dots can be formed into a single layer, and the work function of the transparent electrode used as a conventional anode can be lowered to be used as a cathode, and a metal electrode having a large work function can be used as an anode. In addition, it is possible to fabricate a quantum dot light emitting diode device having an inverted structure.

In addition, the step of forming the electron transporting layer between the laminated transparent electrode layer and the PEIE is inserted to control the injection of electrons and the movement of the holes, thereby maximizing the device efficiency.

FIG. 1 shows a structure (a) and a light emitting diagram (b) of a quantum dot light-emitting diode having a general structure using a conventional transparent electrode formed by depositing a multi-layered layer using quantum dots as an anode Fig.
FIG. 2 is a cross-sectional view illustrating a structure (a) of a quantum dot single-layer light-emitting diode fabricated using a polymer surface modification layer according to an embodiment of the present invention and a structure of a transparent electrode layer stacked in the structure (a) (B) of a quantum dot single-layer light-emitting diode fabricated by further forming an electron transporting layer.
3 is a graph showing the relationship between the quantum dot single-layer light-emitting diode device (a) using the polymer surface modification layer prepared in Example 1 of the present invention and the transparent electrode layer stacked in the structure of Example 1 according to Example 2 and the PEIE And a quantum dot single-layer light-emitting diode device (b) formed by further forming an electron transporting layer.
FIG. 4 is a cross-sectional TEM image of a quantum dot single-layer light-emitting diode device manufactured according to Example 1 of the present invention. The cross-sectional structure according to the quantum dot solution concentration, the spin rate in spin coating process, (B), 1: 2 ratio conditions of (a) a quantum dot of 3 wt%, a spin speed of 4000 rpm and a 1: 2 ratio of poly-TPD: PVK, a quantum dot of 3 wt%, a spin rate of 3000 rpm and a poly- (D) Quantum dots 2 wt%, 4000 rpm spin rate and 1: 1 ratio of poly-TPD: PVK (c), 2 wt% of quantum dots, 4000 rpm spin rate and poly- This is a picture showing the state of.
FIG. 5 is a graph showing energy band diagrams of a quantum dot single-layer light-emitting diode having a structure in which extreme change is caused by a change in work function with respect to an ITO electrode according to Example 1 of the present invention. FIG. 5A shows the energy band diagram of an ultraviolet photoelectron (b) is the highest occupied molecular orbital (HOMO) of PEIE, and (c) is the ITO / PEIE energy diagram.
6 is an energy diagram of an entire device based on a measurement result of a work function change of an ITO electrode due to a PEIE surface modification layer in a light emitting diode device having a quantum dot single layer manufactured according to Embodiment 1 of the present invention.
7 is a current-voltage characteristic curve (a) and a luminance-voltage characteristic curve (b) for a quantum dot single-layer light-emitting diode device manufactured according to Embodiment 1 of the present invention.
8 is a graph showing a comparison curve (a) of a photoluminescence characteristic and a comparison curve (b) of an electroluminescence characteristic after fabrication of a quantum dot colloid solution applied to the fabrication of a quantum dot single layer light emitting diode device in Example 1 of the present invention, to be.
9 is a cross-sectional structure of each of the red, green, blue and white quantum dot light-emitting diodes according to Example 3 produced by inserting an electron transport layer (ZnO layer) into an ITO electrode in Embodiment 2 of the present invention and stacking PEIE .
10 is a graph showing current-voltage characteristic curves (a), (c), (e), and (g) of the red, green, blue and white quantum dot light- (B), (d), (f), and (h) are the current efficiency-luminance-voltage characteristic curves.

Hereinafter, the present invention will be described in more detail as an embodiment.

Layer single-layer light-emitting diode using a polymer surface modification layer having a structure in which a transparent electrode layer, a PEIE (Polyehthylenimine ethoxylated) surface modification layer, a quantum dot single layer and a hole transport layer are laminated on a substrate.

Substrates of a material selected from among glass, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyisosulfonate (PES) can be applied as the substrate in the present invention. Most preferably, a glass substrate can be applied.

The transparent electrode layer formed on the substrate may be a transparent electrode layer made of ITO (indium tin oxide), SnO ₂ , ZnO, carbon nanotube, graphene or silver nanowire. Most preferably, ITO (Indium Tin Oxide) transparent electrodes can be applied.

According to the present invention, a polymer surface modification layer is formed on the transparent electrode layer by PEIE (Polyehthylenimine ethoxylated). Such a PEIE polymer surface modification layer has a molecular structure represented by the following formula (1). When such a PEIE polymer is coated, the work function of the transparent electrode is lowered due to the surface dipole of the amine group contained in the PEIE.

In the above formula (1), x, y and z are each an integer of 1 to 50 as repeating units.

In addition, the PEIE molecule contains an amine group (NH ₂ ) which is a functional group. This amine group forms a surface dipole, thereby lowering the work function of the transparent electrode. These amine groups also enable the formation of a single layer of quantum dots by chemical interaction with the quantum dots formed on the PEIE polymer modifying layer.

In the present invention, the quantum dot single layer formed on the PEIE polymer reforming layer comprises a core, a shell and a ligand; Or cores, shells, shells and ligands; Or consist only of core and shell. The quantum dots include a group of semiconductors such as CdSe, CdS, CdTd, ZnSe, ZnTe, and ZnS. Group compound semiconductor such as indium arsenide (InAs) and indium phosphide (InP), and most preferably a CdSe / ZnS quantum dot can be used.

According to the present invention, it is possible to form a quantum dot monolayer by applying a PEIE polymer modification layer to the transparent electrode, and to reduce the work function of the transparent electrode layer to convert the transparent electrode into a cathode instead of an anode. will be.

A hole transport layer is formed on the single quantum dot layer as described above. Such a hole transport layer may comprise at least one compound selected from the group consisting of NPB (N, N'-bis (1-naphtalenyl) -NN`-bis (phenyl-benzidine), DMFL- NP (N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-9,9'-diphenyl-fluorene), Spiro -NPB (N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-spiro), TPD (N, N'- N, N'-dicarbazole-biphenyl), CBP (4, 4'-N, N'-dicarbazole-biphenyl), PVK N, N'-bis (1 = naphthyl) -naphthyl-N, N'-diphenyl- -1,4'-diamine), TATC (4,4 ', 4 "-tris (N-carbazolyl) -triphenylamine), DNTPD (N, N, N'-diphenyl-amino) phenyl) -N, N'-diphenylbenzidine), TBADN: 3-tert-butyl-9,10-di (naphth- N, N'-carbarzolyl) -9,9-bis [4- (2-ethylhexyloxy) -phenyl] fluorine, or an oxide such as NiO, MoO ₃ , WO ₃ Most preferably, it is formed by a mixture of Poly TPD / PVK (tetraphenyl-diaminophenyl / poly-vinylcarbazole).

According to the present invention, in the quantum dot single layer light emitting diode using the polymer surface modification layer as described above, a positive electrode layer of MoO ₃ / Ag, Au, or Pt is formed as an anode on the hole transport layer.

As an example of a typical typical structure of the quantum dot single layer light emitting diode using the polymer surface modification layer according to the present invention, an ITO (Indium Tin Oxide) layer, a PEIE polymer surface modification layer and a CdSe / ZnS quantum dot single layer And a structure in which a poly TPD / PVK hole transporting layer and a MoO ₃ / Ag anode are sequentially formed thereon.

The method of fabricating the quantum dot single layer light emitting diode using the polymer surface modification layer according to the present invention will be described in more detail as follows.

In the manufacturing method of the present invention, in the step of forming the transparent electrode layer on the substrate, the transparent electrode can be formed by vapor deposition.

In the step of forming the PEIE polymer surface modification layer on the transparent electrode layer, PEIE having an amine group is coated on the surface of the transparent electrode layer by a spin coating method. Such a PEIE polymer surface modification layer may be formed to a thickness of 1 to 20 nm, preferably 1 to 10 nm.

Therefore, it is possible to reduce the work function of a transparent electrode used as a conventional anode due to an amine group, which is a functional group contained in the PEIE, and to use the anode as a cathode, and to use an extreme inverted Inverted structure The quantum dot light emitting diode of the present invention can be manufactured. In the case of the extreme circular structure according to the present invention, since an acidic PEDOT: PSS hole injection layer used in a conventional structure using a conventional transparent electrode as an anode and a metal electrode requiring a low work function are not used as a cathode An additional effect of improving the lifetime of the light emitting element can be obtained.

According to the present invention, in the step of coating a quantum dot colloid solution on the PEIE polymer surface modification layer to form a single quantum dot layer, the quantum dot monolayer is preferably coated by controlling the concentration of the quantum dot colloid solution and the spin coating speed. At this time, the concentration of the quantum dot solution is preferably 2 to 3 wt%, and the spin coating rate is preferably 2000 to 4000 rpm. Here, in addition to spin coating, a coating can be selected in a method selected from nozzle coating, spray coating, inkjet and slit coating. In the present invention, such a single layer coating of a quantum dot enables the formation of a single layer by chemical interaction of the amine group, which is a functional group of the PEIE, with the quantum dot due to the application of the PEIE polymer surface modification layer. That is, for example, when the quantum dots are CdSe / ZnS, the chemical interaction between the surface dipoles of the amine group of PEIE and the sulfur of the quantum dots enables a single layer of quantum dots to be formed.

Unlike the conventional one, the single layer of the quantum dot is coated with a single layer of a uniform shape, so that it exhibits a superior and clear luminescent effect by interaction between the quantum dots compared to the multi-layer quantum dot light emitting layer.

Next, the hole transport layer is formed by coating. Preferably, the poly TPD / PVK mixture is mixed with poly-TPD: PVK at a weight ratio of 1: 0.5 to 3, more preferably 1: 1 to 2 , And the hole transport layer can be formed by spin-coating it at, for example, 2000 to 5000 rpm, more preferably 3000 to 4000 rpm.

In the present invention, the hole transport layer may be coated by a method selected from nozzle coating, spray coating, inkjet, and slit coating in addition to spin coating.

In addition, high quality having such a hole transport layer by forming the anode layer in a conventional manner over 2000 Cd / m ² or more of brightness, preferably at 2500 Cd / m ^2, more preferably at a luminance of 2700 ~ 3500 Cd / m ² A quantum dot single layer light emitting diode can be manufactured.

As described above, according to the present invention, since the work function of the transparent electrode can be lowered to enable extreme change and the transparent electrode is used as the cathode, a hole injection layer of acidic structure and a metal electrode requiring low work function are used as a cathode A thin work function metal is used as a cathode and a use of an acidic hole injection layer is performed by forming a cathode layer using a metal such as MoO ₃ / Ag with a large work function, for example, by using a poly TPD / PVK mixture or the like as a hole transport layer. The lifetime of the light emitting device can be improved.

FIG. 2 is a cross-sectional view conceptually showing the structure of a quantum dot single-layer light-emitting diode using the polymer surface modification layer according to the present invention. FIG. 2 (a) The polymer surface modification layer 13 is formed on the polymer surface modification layer 13 and the work function of the transparent electrode layer 12 is lowered to be used as a negative electrode by lowering the work function to an extreme value to form a quantum dot single layer 14 and a hole transport layer An anode layer 15 and an anode layer 16 are sequentially formed so that electrons are injected from the cathode which is the transparent electrode layer 12 and holes are injected from the anode layer 16 having the metal oxide layer 16a and the metal layer 16b And passes through the hole transport layer 15 to recombine holes and electrons in the quantum dot single layer 14 to emit light.

2 (b) shows another structure in which the electron transport layer 17 is additionally deposited between the transparent electrode layer 12 and the polymer surface modification layer 13 in the structure of FIG. 2 (a) And this structure allows the electron transport layer 17 to control the injection of electrons and the flow of holes, thereby achieving higher efficiency.

According to the present invention, by applying the PEIE polymer surface modification layer on the transparent electrode, a single quantum dot layer can be easily formed even by a simple spin coating process, and in the case of the PEIE surface modification layer, It is possible to provide a quantum dot light emitting diode having an extreme ring structure in which the work function of the transparent electrode is lowered to be used as a cathode and a metal electrode having a larger work function is used as an anode.

The quantum dot single layer light emitting diode using the polymer surface modification layer according to the present invention can be suitably applied to a flat panel display or a planar light source illumination. When the quantum dot single layer light emitting diode is applied, various colors such as blue, red, green, and white can be realized by controlling the size of the quantum dots. In this case, high color purity can be realized to realize a color with a very sharp image quality. It also has an effect of prolonging the life due to extreme ring structure.

Accordingly, the present invention includes a flat panel display including the quantum dot single layer light emitting diode using the polymer surface modification layer of the present invention.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited by the examples.

Example 1

An ITO (Indium Tin Oxide) layer was deposited on the glass substrate, a PEIE polymer surface modification layer was coated to a thickness of 8 nm, and then a CdSe / ZnS colloid quantum dot solution (concentration of 2 to 3 wt%) was spin-coated at 3000 to 4000 rpm, A single layer was formed in order. Then, a hole transport layer was formed by spin coating a poly TPD / PVK mixture thereon, and an anode was formed with MoO ₃ / Ag to fabricate a quantum dot single layer light emitting diode device.

The sectional structure of the thus fabricated light emitting diode is shown in Fig. 3 (a).

Example 2

A quantum dot single layer light emitting diode device was fabricated under the same conditions as in Example 1 except that a ZnO nanoparticle (nano particle, NP) was inserted between the ITO layer and the PEIE polymer surface modification layer to form an electron transport layer, Layer light emitting diode device.

The cross-sectional structure of the thus fabricated light emitting diode is shown in Fig. 3 (b).

Experimental Example 1

In order to confirm the cross-sectional structure of the light emitting diode manufactured in Example 1, a single-layer structure of a quantum dot was confirmed by using an electron microscope to obtain a cross-sectional structure. As shown in FIG. 4, a cross-sectional transmission electron microscope photograph of a quantum dot single-layer light-emitting diode device can confirm a cross-sectional structure according to a concentration of a quantum dot solution, a spin rate in a spin coating process, and a mixed hole transport layer ratio. (A) shows the quantum dots at 3 wt%, 4000 rpm spin rate and poly-TPD: PVK (1: 2) (D) shows the quantum dots at 2 wt%, spin speed of 4000 rpm, and spin speed of 4000 rpm. poly-TPD: PVK (1: 1) ratio condition. 3 (b), 3 (c) and 3 (d), the PEIE polymer surface modifying layer was formed on the ITO transparent electrode, and the quantum dot luminescent layer was a single layer As shown in FIG.

In the structure confirmation experiment, the light emitting diode manufactured in Example 1 is different from the light emitting diode device having the conventional multi-layered quantum dot light emitting layer as shown in FIG. 1 (a), (c), d), a structure having a quantum dot luminescent layer of a single layer is shown.

Experimental Example 2

The current-voltage and luminance-voltage characteristics of the quantum dot single-layer light-emitting diode device fabricated in the above embodiment were confirmed. The results are shown in Fig.

5 (a) shows a secondary cutoff region spectrum of secondary electrons in an ultraviolet photoelectron spectroscopy (UPS), FIG. 5 (b) shows a peak occupied molecular orbital (HOMO) of PEIE, FIG. 5 (c) shows the ITO / PEIE energy diagram. As a result, the surface dipole was formed due to the functional group amine group (NH ₂ ) in the PEIE molecule. As a result, the work function of the ITO electrode was changed from 4.7 eV to 3.08 eV As well. In addition, the amine group in the PEIE polymer surface modification layer can easily form a single layer of CdSe / ZnS quantum dots by interaction with sulfur of the CdSe / ZnS quantum dots.

Also, as a result of the manufacturing process as described above, the energy band diagram of a quantum dot light emitting diode having a structure in which extreme change to a cathode is performed through a change in work function with respect to an ITO transparent electrode was confirmed. The results are shown in Fig.

Experimental Example 3

The current-voltage and luminance-voltage characteristics of the quantum dot single-layer light-emitting diode device fabricated in Example 1 were confirmed. The results are shown in Figs. 7 (a) and 7 (b), respectively.

7 is a graph showing a current-voltage characteristic curve (a) and a luminance-voltage characteristic curve (b) for a quantum dot single layer light-emitting diode device, 2, 3000 ~ 4000rpm) and the spin coating speed. The results showed that the maximum luminance of 2900 Cd / m ² was obtained.

Experimental Example 4

The photoluminescence characteristics of the quantum dot colloid solution and the electroluminescence characteristics after fabricating the device were compared for the light emitting diode device having the quantum dot monolayer fabricated in Example 1, and the results are shown in FIG.

FIG. 8 is a graph (a) and a comparative curve (b) of a photoluminescence characteristic curve and an electroluminescence characteristic curve for a quantum dot light emitting diode device, wherein the photoluminescence measurement of the CdSe / ZnS colloid quantum dot solution used in Example 1 However, when an actual device having a single quantum dot layer was fabricated using the same as in Example 1, it was confirmed that electroluminescence had a wavelength of 633 nm and red-shifted light of about 20 nm.

These results confirmed that the CdSe / ZnS colloid quantum dot application in Example 1 formed a single layer uniformly after the application of the CdSe / ZnS colloid quantum dot to improve the chromaticity by increasing the interaction between the quantum dots.

Example 3

In Example 2, ZnO nanoparticles (NP) were inserted into an ITO electrode as an electron transport layer, and a PEIE polymer surface modification layer was coated to a thickness of 8 nm. Then, red, green, blue, A blue CdSe / ZnS colloidal quantum dot solution (concentration 2 wt%) mixed with a certain ratio of blue was spin-coated at 3000-4000 rpm to form a single quantum dot layer in turn. The TPD / PVK mixture was spin-coated on the hole transport layer to form a hole transport layer, and then an anode was formed with MoO ₃ / Ag to fabricate a quantum dot single layer light emitting diode device.

The cross-sectional structure of the thus fabricated light emitting diode is shown in FIG.

Experimental Example 5

(A), (c), (e), and (g) of the red, green, blue and white quantum dot single-layer light emitting diode devices according to Example 3 produced by the method of Example 2 (B), (d), (f) and (h) of the current efficiency-luminance-voltage characteristic curves were measured. The results are shown in Fig.

10A is a current-voltage characteristic curve for a red quantum dot single-layer light-emitting diode device, FIG. 10B is a current efficiency-luminance-voltage characteristic curve for a red quantum dot light-emitting device, It was confirmed that the current injection efficiency up to 1.3 Cd / A and the luminance of 8000 Cd / m ² can be obtained after inserting the ZnO nanoparticle electron transport layer.

FIG. 10C is a current-voltage characteristic curve for the green quantum dot single-layer light-emitting diode device, and FIG. 10D is a graph showing the current efficiency-luminance-voltage characteristic curve thereof. The current injection efficiency up to 1.2 Cd / A and the luminance of 16000 Cd / m ² can be obtained.

10E is a current-voltage characteristic curve for a blue quantum dot single-layer light-emitting diode device, FIG. 10F is a current efficiency-luminance-voltage characteristic curve, It was confirmed that a current injection efficiency of 0.012 Cd / A and a luminance of 160 Cd / m ² were obtained.

FIG. 10 (g) is a current-voltage characteristic curve for a white quantum dot light emitting diode device in which red, green, and blue quantum dots are mixed at a constant ratio, and (h) shows a current efficiency- And it was confirmed that a current injection efficiency of up to 0.3 Cd / A and a luminance of 4500 Cd / m ² were obtained in the case of a blue quantum dot light emitting device.

The quantum dot single layer light emitting diode using the polymer surface modification layer according to the present invention can be used as a high quality quantum dot single layer light emitting diode improved from the existing multi layer quantum dot light emitting diode.

Particularly, such a quantum dot single-layer light-emitting diode device can be applied to a flat panel display, so that it can be used as a very high-quality light emitting device or an illumination material in place of a flat panel display using an existing organic light emitting diode.

11 - substrate
12 - transparent electrode
13 - Polymer surface modification layer
14 - Quantum dot single layer
15 - hole transport layer
16 - anode layer
17 - electron transport layer

Claims (17)

A structure in which a polymer surface modification layer made of PEIE (Polyehthylenimine ethoxylated) is laminated on a transparent electrode layer laminated on a substrate, a single quantum dot layer is laminated on the polymer surface modification layer, and a hole transport layer is formed on a single quantum dot layer A single-layer quantum dot light-emitting diode using the polymer surface modification layer.
The quantum dot single-layer light-emitting diode according to claim 1, wherein the substrate is selected from the group consisting of glass, polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyisosulfonate (PES).
The quantum dot single-layer light-emitting diode according to claim 1, wherein the polymer surface modification layer is formed to a thickness of 1 to 20 nm.
The method of claim 1, wherein the quantum dot monolayer comprises a core, a shell and a ligand; Or cores, shells, shells and ligands; Or a core and a shell.
The method of claim 1, wherein the quantum dots of the quantum dot single layer are selected from the group consisting of CdSe, CdS, CdTd, ZnSe, ZnTe, or ZnS, Group semiconductor compound of indium arsenide (InAs) or indium phosphide (InP), and at least one quantum dot selected from indium arsenide (InAs) or indium phosphide (InP) semiconductor compound of group 3-5.
The organic electroluminescent device according to claim 1, wherein the hole transport layer comprises at least one compound selected from the group consisting of NPB (N, N'-bis (1-naphtalenyl) -NN`-bis (phenyl- N, N'-diphenyl-9,9'-diphenyl-NPB (N, N'-di (naphthalen- fluorene), Spiro-NPB (N, N'-di (naphthalen-1-yl) -N, N'-
TPD (N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) phenyl) benzidine),
CBP (4,4'-N, N'-dicarbazole-biphenyl), PVK (tetraphenyl-diaminophenyl / poly-vinylcarbazole)
F8BT (poly (9,9-din-octyl-fluorene-sub-benzothiadiazolo),
(N, N'-diphenyl-N, N'-bis (1 = naphtyl) -1,1'-biphenyl-4,4'- diamine), TATC (4,4 ' tris (N-carbazolyl) -triphenylamine),
DNTPD (N, N'-di (4- (N, N'-diphenylamino) phenyl) -N, N'-diphenylbenzidine)
TBADN: 3-tert-butyl-9,10-di (naphth-2-yl) anthracene, and mHOST5 (2,7-Di (N, N'-carbarzolyl) ethylhexyloxy) -phenyl] fluorine), or an oxide selected from the group consisting of NiO, MoO3 and WO3.
The quantum dot single-layer light-emitting diode according to claim 1, wherein the hole transport layer is formed of Poly TPD / PVK (tetraphenyl-diaminophenyl / poly-vinylcarbazole).
The quantum dot single-layer light-emitting diode according to claim 1, wherein a positive electrode layer of MoO ₃ / Ag, Au, or Pt is formed on the hole transport layer.
The quantum dot single-layer light-emitting diode according to claim 1, wherein the transparent electrode layer is extreme-angled and applied as a cathode.
The method of claim 1, wherein an ITO (Indium Tin Oxide) layer, a PEIE polymer surface modification layer, and a CdSe / ZnS quantum dot single layer are sequentially formed on the substrate, and a Poly TPD / PVK hole transport layer and a MoO ₃ / Ag anode layer Layer quantum dot light-emitting diode.
The quantum dot single layer light emitting diode according to claim 1, wherein an electron transport layer is additionally formed between the transparent electrode layer laminated on the substrate and the polymer surface modification layer made of PEIE.
[12] The method of claim 11, wherein a ZnO electron transport layer is formed on an ITO (Indium Tin Oxide) layer, and then a PEIE polymer surface modification layer and a CdSe / ZnS quantum dot single layer are sequentially formed on the substrate, and a Poly TPD / PVK hole transport layer and MoO Lt; RTI ID = 0.0 > ₃ / Ag < / RTI > anode layer.
Forming a transparent electrode layer on the substrate;
Forming a polymer surface modification layer on the transparent electrode layer by PEIE (Polyehthylenimine ethoxylated);
Forming a single quantum dot layer by coating the polymer surface modification layer with a quantum dot colloid solution; And
And forming a hole transporting layer by coating a light emitting material on a single layer of a quantum dot by using the polymer surface modification layer.
14. The manufacturing method of a quantum dot single-layer light emitting diode according to claim 13, wherein an electron transporting layer is additionally formed between the step of forming the transparent electrode layer and the step of forming the polymer surface modification layer.
14. The method of claim 13, wherein the coating is performed in a manner selected from spin coating, nozzle coating, spray coating, inkjet, and slit coating. A method of manufacturing a single layer light emitting diode.
The method of manufacturing a quantum dot single-layer light-emitting diode according to claim 13 or 14, wherein a positive electrode layer is formed of MoO ₃ / Ag, Au, or Pt on the hole transport layer.
A flat panel display comprising a quantum dot single layer light emitting diode according to any one of claims 1 to 12.

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