KR20230024857A - Method for Manufacturing Multilayer Semiconductor Nanoplatelets Using Light-driven Ligand Crosslinking - Google Patents

Abstract

The present invention implements an excellent electroluminescent device with a narrow half-width, optical anisotropy, and excellent out-coupling efficiency by using an anisotropic semiconductor nanoplatelet structure whose shape and emission wavelength are adjustable as a light emitting body. According to the present invention, a nanoplatelet structure was laminated with the arrangement controlled by applying an azide-containing photocrosslinking agent to the nanoplatelet structure. The performance of the device was improved even though a random-direction nanoplatelet structure and a controlled-direction nanoplatelet structure had the same thickness. A method for manufacturing a multilayer semiconductor nanoplatelet structure according to the present invention comprises the steps of: (a) preparing an ink composition including a semiconductor nanoplatelet structure having anisotropy and an azide-containing photocrosslinking agent; (b) forming a semiconductor nanoplatelet structure thin film by applying the ink composition on a substrate; (c) hardening the semiconductor nanoplatelet structure thin film by light irradiation; and (d) manufacturing a multilayer semiconductor nanoplatelet structure by repeating the steps (b) and (c) to laminate the semiconductor nanoplatelet structure thin films.

Description

Method for Manufacturing Multilayer Semiconductor Nanoplatelets Using Light-driven Ligand Crosslinking

The present invention uses anisotropic semiconductor nanoplatelets capable of controlling the shape and emission wavelength as a light emitting body, and multi-layer semiconductor nanoplatelets stacked by light-driven ligand crosslinking of nanoplatelet structures whose arrangement is controlled. A method for manufacturing a structure and a multilayer semiconductor nanoplatelet structure electroluminescent device.

In the case of existing LCD technology, unit price decline is intensifying due to oversupply, and the size of the global market tends to continue to decrease. On the other hand, with the advent of the 4th industrial revolution, the main role of the display has been shifted to a means of displaying information and a window for communication. The demand for is continuously increasing.

In order to popularize VR/AR technology, it is particularly essential to implement high-resolution at the level of 4K/8K to maximize user immersion. Research on a self-luminous light source and pixel formation technology is being actively conducted in order to realize a high resolution of a subminiature mobile display. The popularization of AR, VR, and MR (Mixed or Merged Reality) displays is expected to bring related market expansion, and large-scale markets can be created through application of immersive displays to various fields such as defense, medical care, and education. do. Along with the expansion of the market, new jobs in the field of quantum dot-based materials and application technologies and activation of related industries can be expected.

As the display market expands, demand for displays having high luminance, low power consumption, high integration, and high color gamut is increasing in terms of the market. The nanoplatelet structure is characterized by the realization of an excellent electroluminescent device with a narrow half-width, optical anisotropy, and excellent out-coupling efficiency compared to quantum dots. The nano-plate-like display is expected to be a display that can meet these market demands. To realize this, it is necessary to improve the performance of the electroluminescent device using the nanoplatelet structure.

In order for light to be generated from the luminous body and to be emitted through the device, an angle smaller than the critical angle is required. At this time, the nanoplatelet structure, which is an anisotropic particle, can maximize the light emitted out of the device at an angle smaller than the critical angle when lying down (face-down), compared to quantum dots. When the nanoplatelet structure is arranged in a face-down (in-plane) state, the out-coupling efficiency can theoretically increase to 0.4 due to the dipole alignment of the anisotropic particles, which also increases the theoretical maximum external quantum efficiency (EQE). 40%, which is higher than 20% of quantum dots.

The most ideal form of a device is closely packed light emitters in one layer, but since it is difficult for light emitters to be completely closely packed in reality, two monolayers are considered optimal for quantum dot LEDs. However, due to the nature of anisotropic particles, the degree of arrangement must be considered.

Compared to depositing quantum dots of about 20 nm in quantum dot devices, nanoplatelet structure devices have achieved optimal performance by forming mainly 3 to 5 nm, that is, 1 to 1.5 layers. In order to increase the thickness, it is common to perform spin coating by increasing the concentration of the solution, but in this case, there is a problem in that the out-coupling efficiency rapidly decreases because the degree of arrangement is not controlled. Therefore, if the thickness is increased by adjusting the arrangement, it is expected that the device performance can be improved even if the thickness is increased by preventing the decrease in device performance or minimizing leakage current caused by voids in the device.

Literatures for the stacking of nanoplatelet structures with controlled arrangements mainly use liquid-liquid interface or liquid-air interface assembly methods, but these methods can affect the ITO and ZnO layers of the device to make LED devices. not suitable for

Under such a technical background, the present inventors developed a method of stacking nanoplatelet structures by adjusting the degree of arrangement layer by layer without affecting the lower layer by introducing a photocrosslinking agent, and applied the method to LED.

The above information described in this background section is only for improving the understanding of the background of the present invention, and therefore does not include information that forms prior art known to those skilled in the art to which the present invention belongs. may not be

Korean Patent No. 10-2087299 U.S. Patent No. 16/377,885

Nat. Commun. 2020, 11, 2874 J. Phys. Chem. C 2017, 121, 44, 24837-24844 Nanoscale, 2019, 11, 15072-15082 Nano Lett. 2017, 17, 3837-3843 Nano Lett. 20/20/2020 6459-6465

The nanoplatelet structure enables the implementation of an excellent electroluminescent device with a narrower half width, optical anisotropy, and excellent out-coupling efficiency than quantum dots. An object of the present invention is to provide a nanoplatelet structure electroluminescent device with improved performance by stacking nanoplatelet structures whose arrangement is controlled by introducing a photoactive ligand into the nanoplatelet structure.

In order to achieve the above object, the present invention provides (a) preparing an ink composition comprising semiconductor nanoplatelet structures having anisotropy and a photocrosslinking agent containing an azide group; (b) forming a semiconductor nanoplatelet structure thin film by applying the ink composition on a substrate; (c) curing the thin film by irradiating light to the thin film of the semiconductor nanoplatelet structure; and (d) repeating steps (b) and (c) to laminate thin films of the semiconductor nanoplatelet structure to manufacture a multilayer semiconductor nanoplatelet structure.

The present invention also provides a multilayer semiconductor nanoplatelet structure in which semiconductor nanoplatelet structures are stacked and an electroluminescent device including the same.

According to the present invention, it is possible to realize an excellent electroluminescent device due to the narrow half width at half maximum, optical anisotropy, and excellent out-coupling efficiency, which are characteristics of the nanoplatelet structure, and the nanoplatelet structure is successfully formed by adding a photocrosslinking agent. Cross-linking was confirmed, and the excellent device performance of the multilayer semiconductor nanoplatelet structure was confirmed. In addition, it was confirmed that fine pixel implementation was possible and uniform pattern formation was possible. The process is easy because it is based on the optical lithography technology widely used in the industry.

Structural design of nanoplatelet structures, surface ligand chemistry, and simplification and optimization of manufacturing processes can be widely used in the commercialization of future nanomaterials used in other application fields, and are expected to be applicable to lasers in the long term.

1 is a view showing the mechanism of a photocrosslinking agent containing an azide group and a nanoplatelet structure crosslinked through the mechanism.
2 is a patterning experiment result for confirming an appropriate content of a crosslinker (Crosslinker, LiXer) for crosslinking and stacking nanoplatelet structures.
3 is a result of measuring EQE (External Quantum Efficiency) by increasing only the concentration of the nanoplatelet structures in order to confirm the effect of the thickness in a thin film state of the randomly oriented nanoplatelet structures.
Figure 4 is a schematic view showing 3 ML Random, which is spin-coated by increasing the concentration to the thickness of 3 monolayers, and 3 ML in-plane, which is laminated layer by layer using an optical crosslinking agent.
5 is a result showing the thickness of the thin film according to the presence or absence of a crosslinking agent and the concentration of the nanoplatelet structure solution.
6 is a result of confirming the arrangement on the film through GISAXS (Grazing incident small angle x-ray scattering) analysis.
7 is a result of confirming film morphology (roughness) through atomic force microscopy (AFM).
8 is a result of measuring 3 ML Random and 3 ML in-plane EQE (External Quantum Efficiency).
9 is a result of luminance and electrical characteristics of 3 ML Random and 3 ML in-plane.
10 shows an energy diagram in the device by measuring the valence band energy of 3 ML random and 3 ML in-plane through UPS (Ultraviolet photoelectron spectroscopy).
11 is a table showing the results of measuring angle-dependent photoluminescence of 3 ML random and 3 ML in-plane and the ratio of light inside and outside the critical angle of total reflection.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is one well known and commonly used in the art.

The present invention provides a device with improved performance by laminating nanoplatelet structures using an optical lithography technique.

Photolithography technology uses photosensitive organic/inorganic molecules to photocrosslink only the portion of a quantum dot thin film that receives light of a specific wavelength, and the crosslinking agent containing an azide group forms radicals when exposed to UV with a wavelength of 254 nm. It is inserted into the C-H group and crosslinking occurs to the ligand, resulting in cross-linking of the particles. The present invention is easy to process because it is based on an optical lithography technique widely used in the industry.

The nanoplatelet structure is characterized by enabling the implementation of an excellent electroluminescence (EL) device with a narrow half-width, optical anisotropy, and excellent out-coupling efficiency. In particular, when the arrangement is adjusted, better performance than quantum dot LEDs can be realized.

In one embodiment of the present invention, a photocrosslinking agent containing an azide group was applied to the nanoplatelet structures to adjust the degree of arrangement of the nanoplatelet structures and stacked. When stacked in face-down form, the performance of the device was improved, and the difference in EL performance was shown even though the thin film thickness of the random-direction nanoplatelet structure and the control-direction nanoplatelet structure was the same.

In the present invention, it was confirmed that the nanoplatelet structure was successfully photocrosslinked by adding a photocrosslinking agent, the arrangement of the particles was adjusted and stacked, and the device performance was improved.

Accordingly, in one aspect, the present invention provides: (a) preparing an ink composition comprising semiconductor nanoplatelets having anisotropy and a photocrosslinking agent containing an azide group; (b) forming a semiconductor nanoplatelet structure thin film by applying the ink composition on a substrate; (c) curing the thin film by irradiating light to the thin film of the semiconductor nanoplatelet structure; and (d) repeating steps (b) and (c) to laminate semiconductor nanoplatelet structure thin films to manufacture a multilayer semiconductor nanoplatelet structure.

In the present invention, the photocrosslinking agent is a photoactive crosslinking agent containing an azide group, and may be characterized in that it is represented by Formula 1 below, but is not limited thereto.

[Formula 1]

In the present invention, the step (a) of preparing the ink composition may include mixing a solution in which the nanoplatelet structures are dispersed in an organic solvent and a solution in which a crosslinking agent is dispersed in an organic solvent are mixed with each other. Alternatively, the nanoplatelet structure may be dispersed in octane, and the crosslinking agent may be dispersed in toluene, but is not limited thereto.

In the present invention, the semiconductor nanoplatelet structure may have anisotropy and have a core/shell structure, preferably including CdSe/CdZnS, but is not limited thereto. .

In the present invention, the weight ratio of the crosslinking agent to the nanoplatelet structure may be 3 wt% to 15 wt%. If the weight ratio of the crosslinking agent to the nanoplatelet structure is less than 3 wt%, crosslinking may not occur, and if it is greater than 15 wt%, the insulation phenomenon due to the crosslinking agent may cause a problem of deteriorating the performance of the device. . Preferably it may be characterized in that 5 to 15 wt%, more preferably 10 wt%, but is not limited thereto.

In the present invention, the concentration of the nanoplatelet structure may be characterized in that 2 mg / ml to 15 mg / ml. If the concentration of the nanoplatelet structure is less than 2 mg/ml, a problem may occur in which the first layer of the thin film cannot be formed, and if it is greater than 15 mg/ml, a problem of particle arrangement in the thin film may occur due to attraction between particles. . Preferably, the concentration of the nanoplatelet structure in the first layer is 2 mg/ml to 10 mg/ml, more preferably 2 mg/ml to 7 mg/ml, and most preferably 5 mg/ml. However, it is not limited thereto.

In the present invention, the ink composition may be applied after applying the metal oxide nanoparticles to the substrate, and the metal oxide nanoparticles may be zinc oxide nanoparticles.

In the present invention, step (c) may be characterized by irradiating light having a wavelength of 250 nm to 260 nm. Preferably, the semiconductor nanoplatelet structure thin film may be cured by irradiating a light source of about 254 nm for about 5 seconds, but is not limited thereto.

In the present invention, the step (d) is repeated 2 to 5 times so that the nanoplatelet structures are arranged in an in-plane face-down state and stacked in 2 to 5 layers. can be characterized. Preferably, it may be characterized in that it is laminated in three layers, but is not limited thereto.

In one embodiment of the present invention, device performance was improved despite the fact that the nanoplatelet structures in a random assembly and the nanoplatelet structures in a controlled direction arrangement (particularly, in-plane arrangement) had the same thickness.

In another aspect, the present invention, a substrate; And a multi-layer semiconductor nano-platelet structure, characterized in that a semiconductor nano-platelet structure having anisotropy is laminated on the substrate, and the semiconductor nano-platelet structure is crosslinked by a photocrosslinking agent containing an azide group ( semiconductor nanoplatelets).

In the present invention, the photocrosslinking agent may be characterized in that it is represented by the formula (1).

In the present invention, the semiconductor nanoplatelet structure may be characterized in that it includes CdSe/CdZnS.

In the present invention, the semiconductor nanoplatelet structure may be arranged in an in-plane face-down state and stacked in two to five layers.

Referring to FIGS. 1 and 2 , the semiconductor nanoplatelet structure includes a substrate and a semiconductor nanoplatelet structure positioned on the substrate, crosslinked by a photocrosslinking agent containing an azide group, and having anisotropy. A metal oxide nanoparticle layer including metal oxide nanoparticles may be positioned between the substrate and the semiconductor nanoplatelet structure.

In another aspect of the present invention, the multi-layer semiconductor nanoplatelet structure; And it relates to an electroluminescence device comprising an electrode.

In the present invention, the electroluminescent device comprises a substrate; a pair of electrodes positioned on the substrate; and a multilayer semiconductor nanoplatelet structure positioned on the substrate.

Specifically, in one embodiment of the present invention, a CdSe / CdZnS core shell nanoplatelet structure was prepared, mixed with a photocrosslinking agent (10 wt%) at a concentration of 1 monolayer thickness (= 5 mg / ml), and spin-coated on a substrate, , photo-crosslinking was performed with UV light at a wavelength of 254 nm and stacked in three layers (FIG. 1).

When rapid evaporation occurs at a low concentration, the nanoplatelet structure rises on the substrate in a face down form. Since the spin coating used in the present invention induces very rapid evaporation, spin coating at a concentration of 1 monolayer results in a face down coating. this will happen At this time, the nanoplatelet structure was coated in the form of 1 monolayer face down using a photocrosslinking agent, crosslinked and fixed, and then stacked with several layers inducing face down by laying and fixing 1 monolayer again.

In order to confirm the amount of photocrosslinking agent that effectively photocrosslinks the nanoplatelet structure, the weight ratio of the photocrosslinker to the nanoplatelet structure was adjusted and confirmed. To this end, after spin coating, a mask was raised and a patterning experiment was conducted through exposure at a wavelength of 254 nm, and it was confirmed that crosslinking effectively occurred when 10 wt% of a crosslinker (Crosslinker, LiXer) was added (FIG. 2).

In one embodiment of the present invention, a crosslinking agent having two azide groups was used as a photocrosslinking agent, and azide forms a nitrine radical upon UV exposure (254 nm), which is C-H inserted into an adjacent alkyl chain. The reaction proceeds (FIG. 1).

The most ideal state in a device is a closely packed state, in which one layer of light emitting elements is laid. However, in reality, since it is difficult for the light emitting body to be completely closely packed, about 2 monolayers are considered optimal for quantum dot LEDs. However, due to the nature of anisotropic particles, they have a feature that requires consideration of their arrangement.

In quantum dot devices, quantum dots are deposited at about 20 nm, whereas nanoplatelet structure devices mainly form 3 to 5 nm, that is, 1 to 1.5 layers, to achieve optimal performance (external quantum efficiency, EQE). In order to increase the thickness, it is common to perform spin coating by increasing the solution concentration, but in this case, the arrangement of the nanoplatelet structures is not controlled, resulting in a mixture of face down and edge up arrangements, which causes a sharp drop in out-coupling efficiency. do.

Therefore, if the thickness is increased by well controlling the arrangement of the nanoplatelet structures, it is expected that the device performance can be improved even if the thickness is increased by preventing the decrease in device performance or by minimizing the generation of leakage current due to the formation of voids in the device.

In order to confirm the effect of the thickness in the Randomly assembly (random orientation arrangement) state, the performance was confirmed while increasing only the concentration of the nanoplatelet structure. EQE is improved from 4 mg/ml (1 layer) to 6 mg/ml, but EQE decreases sharply at 12 mg/ml, so the performance of the device has an optimal point at a certain thickness and decreases beyond that. It is expected that the device performance can be maximized by controlling the thickness of the thin film and the arrangement of the nanoplatelet structures (FIG. 3).

According to the prior literature for such well-controlled self-assembly, liquid-liquid interface or liquid-air interface assembly is mainly used. This method is a method of aligning a nanoplatelet structure layer on a subphase solvent and stacking it on a substrate by repeating subphase removal. In this way, recent papers from the Demir group face down nanoplatelet structures (NPLs) and stack them in multiple layers to use them for laser applications (Nano Lett. 2020, 20, 9, 6459-6465). However, this method is not suitable for making a device that requires arranging NPLs on the ITO and ZnO layers, as it may affect the lower layer.

In the present invention, the performance of the electroluminescent device was confirmed by inducing different arrangements of the thickness of 3 monolayers. In the spin coating process, the concentration of the nanoplatelet structure solution is increased to create a thickness of 3 monolayers, and the case where the arrangement is irregular due to the attraction between the particles is called 3 ML Random and is used as a comparative example. In addition, a photocrosslinking agent is mixed with the nanoplatelet structure solution and rapidly evaporated at a low concentration of 1 monolayer to induce an in-plane arrangement, and the sample stacked three times is called 3ML in-plane and is used as an example. A diagram of the expected arrangement is shown in FIG. 4 . In addition, the thickness of the thin film constantly increases when laminated using a photocrosslinking agent, but the thickness does not constantly increase when laminated repeatedly without using a photocrosslinking agent, thereby confirming the formation of a multilayer nanoplatelet structure thin film ( Fig. 5).

In an embodiment, in order to check whether the in-plane arrangement is maintained, the intensity of the distance between the particles corresponding to each Q is compared through GISAXS (Grazing incident small angle x-ray scattering) to face in the 3 ML in-plane embodiment. It was confirmed that the ratio of the array of -down was more prominent than that of 3 ML Random (FIG. 6). In addition, when confirmed through AFM (Atomic force microscopy), it was confirmed that the roughness was further reduced in the 3 ML in-plane and the film morphology was improved (FIG. 7).

EQE (External quantum efficiency), current density, and luminance are shown in FIGS. 8 and 9, and all optical and electrical properties are improved. In particular, it was confirmed that the EQE representing representative device performance rose from 6.93% in 3 ML Random to 8.59% in 3 ML in-plane.

These causes include efficient charge transport and increased light extraction efficiency. First, when the valence band energy was checked by UPS (Ultraviolet photoelectron spectroscopy), the 3 ML in-plane valence band was CBP (4,4′-Bis(N-carbazolyl)-1,1′-biphenyl of the hole transport layer). ), the charge imbalance problem is solved with the effect of lowering the hole barrier due to the lowering of the energy level difference. Second, by measuring angle dependent photoluminescence, it was confirmed that when light escapes from the device, the ratio of the amount of light entering the critical angle of total reflection to the amount outside (light extraction efficiency) is higher in the 3 ML in-plane embodiment (FIG. 10). , Fig. 11).

As such, the 3 ML in-plane embodiment shows improved device performance over the 3 ML Random Comparative Example.

In addition, it was confirmed that there was almost no loss during lamination of the film PLQY, and the out-coupling efficiency of the nanoplatelet structure reached or exceeded the theoretical maximum out-coupling efficiency of quantum dots of 0.20.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example One: CdSe / CdZnS semiconductor of the nanoplatelet structure manufacturing

Compositional Grading for Efficient and Narrowband Emission in CdSe-Based Core/Shell Nanoplatelets, Chem. Mater. 2019, 31, 9567-9578, luminescent core-shell structured cadmium selenide nanoplatelets (CdSe/CdZnS core-shell nanoplatelets) were prepared and purified.

Example 2: containing an azide group photocrosslinking preparation

As an azide group-based crosslinking agent, a photocrosslinking agent represented by Chemical Formula 1 below was used.

[Formula 1]

Example 3: nanoplatelet structure and photocrosslinking agent manufacture of ink compositions including

About 100 mg of the CdSe/CdZnS nanoplatelet structure synthesized in Example 1 was dispersed in octane so that the concentration of the entire solution was about 5 mg/ml, and then about 10 mg of the crosslinking agent including the azide derivative of Example 2 was added to octane. It was added dispersed in about 1/10 of the volume of toluene. Accordingly, the weight ratio of the crosslinking agent to the nanoplatelet structure was set to 10:1.

Example 4: semiconductor nanoplatelet structure Lamination of thin films

After sequentially washing the Si-SiO ₂ wafer or glass substrate with distilled water, acetone, and isopropanol, about 20 mg/ml ZnO nanoparticles were spin-coated at about 4000 rpm for about 30 seconds. Then, after applying the mixture of the nanoplatelet structure prepared in Example 3 and a crosslinking agent including an azide group, spin-coating was performed at about 4000 rpm for about 30 seconds. Then, it is dried in an argon atmosphere to form a thin film.

A light source of about 254 nm is irradiated for about 5 seconds to cure the thin film of the semiconductor nanoplatelet structure. This process was repeated to complete the lamination of the nanoplatelet structure.

Example 5: Same thickness, different arrangement of semiconductors nanoplatelet structure Fabrication of thin films

Semiconductor nanoplatelet structure thin films having the same thickness but different arrangements are shown in FIG. 4 . The thickness of 3 monolayers, but irregularly arranged are called 3 ML Random, and the in-plane array with the thickness of 3 monolayers is called 3 ML in-plane.

The 3ML random thin film was spin-coated by dispersing the concentration of the nanoplatelet structure solution in Example 4 in octane at 15 mg/ml. The 3ML in-plane thin film was laminated three times with photocrosslinking in Example 4 by dispersing the nanoplatelet structure solution at a concentration of 5 mg/ml in octane.

In FIG. 5 , it was confirmed that when spin-coating was performed with photo-crosslinking by adding a photo-crosslinking agent, the thickness was constantly increased and laminated without layer loss, and when spin-coating was performed without a photo-crosslinking agent, it was confirmed that the thickness did not increase. In addition, in FIG. 6, it can be seen that the thickness of the nanoplatelet structures is similar, but the arrangement is different.

Example 6: Surface roughness measurement

After forming the thin film of the nanoplatelet structure according to the presence or absence of the photocrosslinking agent, the roughness of the thin film was compared. The roughness of the thin film (with LiXer) prepared according to Example 4 and the thin film (without Lixer) prepared in the same manner as in Example 4, except that the crosslinking agent was not used, was measured with an atomic force microscope.

As a result, in the case of 3ML in-plane, it was confirmed that a relatively lower level of roughness than 3ML Random appeared (FIG. 7). Therefore, the roughness of the thin film is reduced when the photocrosslinking agent is present, indicating the superiority of the thin film.

Example 7: Measurement of degree of alignment of particles

After forming the thin film of the nanoplatelet structure according to the presence or absence of the photocrosslinking agent, the alignment of the particles in the thin film was compared. The degree of alignment of the particles in the 3ML Random and 3ML in-plane thin films prepared according to Examples 4 and 5 was measured by GISAXS.

According to the 2D GISAXS results of FIG. 6, the nanoplatelet structure was formed as a thin film on ITO/ZnO depending on the presence or absence of a crosslinking agent, and the assembly was confirmed through GISAXS. In FIG. 6, the distances between the nanoplatelet structures in 1, 2, and 3 of the upper figure are shown according to positions 1, 2, and 3 of the lower graph. In the 3ML in-plane, a clearer No. 1 face-down peak appears, and it can be seen that the No. 3 edge up is relatively reduced.

Accordingly, the effect of the photocrosslinking agent on the degree of alignment of the semiconductor nanoplatelet structure particles can be confirmed. It can be seen that when photo-crosslinking was performed by laminating at a low concentration of the nanoplatelet structures, the thin film was formed in an in-plane arrangement compared to when the thin film was formed by simply increasing the concentration.

Example 8: Measuring device performance

After forming the thin film of the nanoplatelet structure according to the presence or absence of the photocrosslinking agent, the optical and electrical properties of the thin film were compared. The optical properties and electrical properties of the 3ML Random and 3ML in-plane prepared according to Example 5 were measured. Regarding optical properties, EQE (External Quantum Efficiency) according to current density was measured, and current density and brightness according to voltage were measured in relation to electrical characteristics.

As a result, the performance of the device composed of the 3ML in-plane thin film showed better results than the performance of the device composed of the 3ML random thin film (FIGS. 8 and 9). It can be seen that the EQE is higher and the charge transfer is also improved.

When the valence energy level of the nanoplatelet structure was measured through the UPS in FIG. 10, it was confirmed that the energy of the 3ML in-plane thin film was formed closer to the hole transport layer (HTL) than the 3ML Random thin film. Therefore, it can be expected that the energy barrier is lowered when the hole moves and the charge imbalance is resolved. In addition, it can be expected from the angle dependent photoluminescence result in FIG. 11 that when the in-plane array has an in-plane arrangement, the ratio of light entering the total reflection critical angle increases, resulting in excellent light extraction efficiency.

As a result, it can be confirmed that better performance of the electroluminescent device appears when the thin film is formed in an in-plane direction through the photocrosslinking agent.

Having described specific parts of the present invention in detail above, it will be clear to those skilled in the art that these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. will be. Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (13)

A method for producing a multilayer semiconductor nanoplatelet structure comprising:
(a) preparing an ink composition comprising semiconductor nanoplatelets having anisotropy and a photocrosslinking agent containing an azide group;
(b) forming a semiconductor nanoplatelet structure thin film by applying the ink composition on a substrate;
(c) curing the thin film by irradiating light to the thin film of the semiconductor nanoplatelet structure; and
(d) repeating steps (b) and (c) to laminate semiconductor nanoplatelet structure thin films to prepare a multilayer semiconductor nanoplatelet structure.
The method of claim 1, wherein the photocrosslinking agent is represented by Formula 1 below.
[Formula 1]

The method of claim 1, wherein the semiconductor nanoplatelet structure has a core/shell structure.
4. The method of claim 3, wherein the semiconductor nanoplatelet structure comprises CdSe/CdZnS.
The method of claim 1, wherein the weight ratio of the photocrosslinking agent to the nanoplatelet structure is 3 wt% to 15 wt%.
The method of claim 1, wherein the concentration of the nanoplatelet structure is 2 mg/ml to 15 mg/ml.
The method of claim 1, wherein step (c) irradiates light having a wavelength of 250 nm to 260 nm.
The method of claim 1, wherein step (d) is repeated 2 to 5 times so that the nanoplatelet structures are arranged in an in-plane face-down state and stacked in 2 to 5 layers. Method for producing a multi-layer semiconductor nanoplatelet structure, characterized in that.
Board; And a multi-layer semiconductor nano-platelet structure, characterized in that a semiconductor nano-platelet structure having anisotropy is laminated on the substrate, and the semiconductor nano-platelet structure is crosslinked by a photocrosslinking agent containing an azide group ( semiconductor nanoplatelets).
10. The multilayer semiconductor nanoplatelet structure according to claim 9, wherein the photocrosslinking agent is represented by Formula 1 below.
[Formula 1]

10. The multilayer semiconductor nanoplatelet structure according to claim 9, wherein the semiconductor nanoplatelet structure comprises CdSe/CdZnS.
10. The multilayer semiconductor nanoplatelet structure according to claim 9, wherein the semiconductor nanoplatelet structure is arranged in an in-plane face-down state and stacked in two to five layers.
The multilayer semiconductor nanoplatelet structure according to any one of claims 9 to 12; and an electroluminescence device comprising an electrode.

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