KR102835814B1 - Solvent free pattering method of qunatum dots - Google Patents

Abstract

The solvent-free patterning method of the quantum dot of the present invention comprises the steps of preparing a substrate, laminating an elastomeric mask layer on the substrate, forming a pattern on the elastomeric mask layer, selectively removing the elastomeric mask layer according to the formed pattern, and laminating a quantum dot layer on the selectively removed elastomeric mask layer. Accordingly, the present invention can implement a high-resolution quantum dot pattern using a solvent-free patterning technique by applying an elastomeric mask layer.
This invention was conducted with the support of LGD Co., Ltd. and the Industry-Academic Cooperation Project (No. 20191395).

Description

{SOLVENT FREE PATTERING METHOD OF QUNATUM DOTS}

The present invention relates to a solvent-free patterning method of quantum dots, and more particularly, to a solvent-free patterning method of quantum dots capable of implementing a high-resolution quantum dot pattern using a solvent-free patterning technique by applying an elastomeric mask layer.

Patterning quantum dots (QDs) with sub-10 μm pixels is a critical but very challenging task. The quality of QDs deteriorates significantly when they come into contact with most chemicals, including solvents and water. Therefore, conventional photolithography, which is one of the methods for patterning sub-10 μm features with precise alignment, is not compatible with QDs. Fine metal mask (FMM) method and inkjet printing are the most common methods for QD patterning. However, the fine metal mask method requires periodic cleaning and has microforming problems due to the limitation of the metal mask thickness. In addition, nozzle clogging is a common problem in inkjet printing technology. More importantly, both of these technologies have the problem that they cannot reliably pattern sub-10 μm features.

In addition, since the patterning step of the quantum dot layer based on the solution process must be applied multiple times, not only is the manufacturing process difficult, but there is also a problem that the performance of the quantum dot layer deteriorates. Although various solution process methods including inkjet printing are being developed, the first patterned quantum dot layer may be exposed to a large number of solvents and ultraviolet rays in unit processes such as the mask forming process, exposure process, etching process, and developing process, which may damage the quantum dot layer or cause serious performance degradation. In addition, if the solution process is performed multiple times, the time that the quantum dots are exposed to the air increases, which may have a negative effect on the stability of the quantum dots.

Republic of Korea Patent No. 10-1822500

The present invention is intended to solve the above problems, and provides a solvent-free patterning method of quantum dots that can implement a high-resolution quantum dot pattern using a solvent-free patterning technique by applying an elastic mask layer.

In order to achieve the above purpose, a method for solvent-free patterning of quantum dots according to one embodiment of the present invention may include the steps of: providing a substrate; laminating an elastic mask layer on the substrate; forming a pattern on the elastic mask layer; selectively removing the elastic mask layer according to the formed pattern; and laminating a quantum dot layer on the selectively removed elastic mask layer.

Additionally, the step of preparing the substrate may include surface-treating the substrate using oxygen plasma.

Additionally, the elastic mask layer may be a polymer bilayer including a hydrophobic polymer and an organic polymer.

Here, the hydrophobic polymer comprises at least one of perfluorooctyltrichlorosilane (FOTS), octadecyltrichlorosilane (OTS), perfluorodecyltrichlorosilane (FDTS), dichlorodimethylsilane (DIMS), perfluorodecyltrichlorosilane (FTCS), dichlorodimethylsilane (DDMS), and diamond-like carbon (DLC).

The above organic polymers are epoxy, polycarbonate (PC), polyethylene naphthalate (PEN), polynorbornene (PN), polyacrylate, polyvinyl alcohol (PVA), polyimide (PI), polyethylene terephthalate (PET), polyethersulfone (PES), polystyrene (PS), polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), polyamide (PA), polybutyleneterephthalate (PBT), polyester, polydimethylsiloxane (PDMS), and It may contain one or more organic polymers such as polymethylmethacrylate (PMMA).

In addition, the step of laminating an elastic mask layer on the substrate can form the elastic mask layer by drop casting FOTS on the substrate and then spin coating PMMA.

Here, the PMMA may be dissolved in toluene.

In addition, the step of selectively removing the elastic mask layer may include removing the elastic mask layer exposed according to the pattern, and the exposed elastic mask layer may be removed by etching with oxygen plasma.

Additionally, the remaining area of the removed elastic mask layer can be surface treated with CF ₄ plasma.

In addition, the quantum dot is formed of a core-shell structure, and the core may include at least one of CdSe, CdS, ZnS, ZnSe, CdTe, CdZnS, PbSe, AgInZnS, and ZnO, and the shell may include at least one of CdSe, CdS, ZnS, ZnSe, CdTe, CdZnSe, PbSe, TiO, SrSe, and HgSe.

Additionally, the quantum dots may have a CdSe core and CdZnSe shell structure with TiO ₂ ligands.

In addition, after the step of laminating a quantum dot layer on the elastic mask layer, the elastic mask layer is selectively removed, and the substrate on which the quantum dot layer is laminated and the remaining area of the removed elastic mask layer are peeled off with the photoresist-coated elastic mask layer using an adhesive polymer.

After the above peeling step, a passivation layer can be laminated on the substrate on which the quantum dot layer is laminated.

The solvent-free patterning method of quantum dots according to the present invention and the photoelectric device using the same can implement a high-resolution quantum dot pattern using a solvent-free patterning technique by applying an elastic mask layer.

FIG. 1 is a flow chart for explaining a solvent-free patterning method of quantum dots according to one embodiment of the present invention.
FIG. 2 is a process flow diagram for explaining a process of manufacturing a photoelectric device using a solvent-free patterning method of quantum dots according to one embodiment of the present invention.
Figure 3 is a drawing showing a scanning electron microscope image of the quantum dot pattern surface by process of Figure 2.
FIG. 4 is a schematic diagram illustrating a solvent-free patterning method of quantum dots using an elastic mask according to one embodiment of the present invention.
FIG. 5 is a diagram showing the performance results of a photoelectric device using a solvent-free patterning method of quantum dots according to one embodiment of the present invention.

Hereinafter, in order to clarify the technical idea of the present invention, a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. In describing the present invention, if it is judged that a detailed description of a related known function or component may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In the drawings, components having substantially the same functional configuration are given the same reference numbers and symbols as much as possible even if they are shown in different drawings. For convenience of explanation, devices and methods are described together when necessary.

FIG. 1 is a flow chart for explaining a solvent-free patterning method of quantum dots according to one embodiment of the present invention.

Referring to FIG. 1, a method for solvent-free patterning of quantum dots first provides a substrate (S101). Here, the substrate may include an inorganic substrate of any one of gallium nitride (GaN), silicon (Si), silicon carbide (SiC), germanium (Ge), gallium arsenide (GaAs), gallium phosphide (GaP), gallium arsenide phosphide (GaAsP), gallium antimony (GaSb), boron nitride (BN), zinc oxide (ZnO), magnesium oxide (MgO), indium phosphide (InP), arsenic phosphide (InAs), sapphire, quartz, and glass. In an embodiment, the substrate may use a glass substrate.

At this time, the substrate can be surface treated with oxygen plasma. Accordingly, the adhesion on the substrate can be improved.

Thereafter, an elastic mask layer is laminated on the substrate (S103). Here, the elastic mask layer may be formed of a polymer double layer.

Specifically, the polymer bilayer may include a hydrophobic polymer and an organic polymer. Here, the hydrophobic polymer may include at least one of perfluorooctyltrichlorosilane (FOTS), octadecyltrichlorosilane (OTS), perfluorodecyltrichlorosilane (FDTS), dichlorodimethylsilane (DIMS), perfluorodecyltrichlorosilane (FTCS), dichlorodimethylsilane (DDMS), and diamond-like carbon (DLC). In an embodiment, the hydrophobic polymer may use perfluorooctyltrichlorosilane (hereinafter referred to as 'FOTS').

Here, the organic polymer is epoxy, polycarbonate (PC), polyethylene naphthalate (PEN), polynorbornene (PN), polyacrylate, polyvinyl alcohol (PVA), polyimide (PI), polyethylene terephthalate (PET), polyethersulfone (PES), polystyrene (PS), polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), polyamide (PA), polybutyleneterephthalate (PBT), polyester, polydimethylsiloxane (PDMS), and It may include one or more organic polymers from polymethylmethacrylate (PMMA). In an embodiment, the organic polymer may be polymethylmethacrylate (hereinafter referred to as 'PMMA').

In an embodiment, the FOTS may be drop-casted on a substrate and then PMMA may be spin-coated to form an elastomeric mask layer. Here, the PMMA may be dissolved in toluene. At this time, the elastomeric mask layer may produce a PMMA film having a thickness of 560 nm. Thereafter, the elastomeric mask layer laminated on the substrate may be baked on a hot plate at 120°C for 10 minutes.

Then, after coating photoresist on the elastic mask layer, a pattern is formed (S105). That is, the photoresist coated on the elastic mask layer is exposed according to the quantum dot pattern, and then the photoresist is removed to form a quantum dot pattern.

Thereafter, the elastic mask layer is selectively removed according to the formed pattern (S107). That is, the elastic mask layer exposed by the patterned photoresist is removed. At this time, the exposed elastic mask layer can be removed by etching with oxygen plasma.

Next, the remaining area of the removed elastic mask layer is surface-treated with CF ₄ plasma. That is, the remaining photoresist and substrate surface can be surface-treated with CF ₄ plasma. This treatment with CF ₄ plasma can increase the yield and thickness of the quantum dot pattern because the adhesiveness of the fluorine polymer is weak.

Then, a quantum dot layer is laminated on the optionally removed elastic mask layer (S109). That is, quantum dots are spin-coated on the elastic mask layer coated with patterned photoresist and cured on a hot plate at 100°C for 2 minutes and at 180°C for 10 minutes. Here, the quantum dots are CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, CuInS2, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, PbSe, PbS, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP, InAs, Any one or a combination of two or more of GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs, GaInNP, GaInNAs, GaInPAs, InAlNP, InAlNAs, and InAlPAs may be included. However, the present invention is not limited thereto. In an embodiment, the quantum dot may have a core-shell structure. Here, the core may include any one or more of CdSe, CdS, ZnS, ZnSe, CdTe, CdZnS, PbSe, AgInZnS, and ZnO, and the shell may include any one or more of CdSe, CdS, ZnS, ZnSe, CdTe, CdZnSe, PbSe, TiO, SrSe, and HgSe. Preferably, the quantum dots may have a CdSe core and CdZnSe shell structure with TiO ₂ ligands for green or red color conversion.

Thereafter, the photoresist-coated elastic mask layer and the substrate on which the cured quantum dots are laminated are peeled off using an adhesive polymer. That is, the substrate on which the quantum dot layer is laminated and the photoresist-coated elastic mask layer of the remaining area of the removed elastic mask layer are peeled off using an adhesive polymer. Here, peeling means mechanical peeling.

Ultimately, only the quantum dot pattern remains on the substrate.

Therefore, the present invention prevents the quantum dots from coming into contact with the solvent during the entire quantum dot patterning process.

FIG. 2 is a process flow diagram for explaining a process of manufacturing a photovoltaic device using a solvent-free patterning method of quantum dots according to one embodiment of the present invention, FIG. 3 is a drawing showing a scanning electron microscope image of a quantum dot pattern surface according to each process of FIG. 2, and FIG. 4 is a schematic diagram showing a solvent-free patterning method of quantum dots using an elastic mask according to one embodiment of the present invention.

Referring to FIGS. 1 to 3, a method for manufacturing a photoelectric device using a solvent-free patterning method of a quantum dot of the present invention comprises, in step (a), preparing a substrate (110) and performing cleaning. In an embodiment, the substrate (110) may be a glass substrate.

At this time, in step (b), the substrate (110) can be surface treated with oxygen (O ₂ ) plasma. Accordingly, adhesion on the substrate can be improved.

Thereafter, in steps (c) and (d), an elastic mask layer (120, 130) is laminated on the substrate (110). In an embodiment, the elastic mask layer (120, 130) is formed of a polymer bilayer and may include a hydrophobic polymer (120) and an organic polymer (130). Here, the hydrophobic polymer may use FOTS, and the organic polymer may use PMMA.

According to an embodiment, the FOTS (120) may be drop-casted on the substrate (110) and then PMMA (130) may be spin-coated to form an elastic mask layer (120, 130). Here, the PMMA may be dissolved in toluene. At this time, the elastic mask layer may produce a PMMA (130) having a thickness of 560 nm. Thereafter, the elastic mask layer (120, 130) laminated on the substrate (110) may be heat-treated on a hot plate at 120°C for 10 minutes. At this time, the elastic mask layer (120, 130) maintains a surface energy level suitable for peeling.

And, in step (e), after coating photoresist (PR) on the elastic mask layer (120, 130), a pattern (h) is formed. That is, the photoresist coated on the elastic mask layer is exposed according to the pattern (h), and then the photoresist is removed to form the pattern (h).

Thereafter, in step (f), the elastic mask layer (120, 130) is selectively removed according to the formed pattern (h). That is, the elastic mask layer (120, 130) exposed by the patterned photoresist (PR) is removed. At this time, the exposed elastic mask layer (120, 130) can be removed by etching with oxygen plasma. Then, the remaining photoresist (PR) and the surface of the substrate (110) can be treated with CF ₄ plasma. This treatment with CF ₄ plasma can increase the yield and thickness of the quantum dot pattern because the adhesiveness of the fluorine polymer is weak.

Then, in step (g), a green quantum dot layer (140) is laminated on the optionally removed elastic mask layer (120, 130). That is, the green quantum dot (140) is spin-coated on the elastic mask layer (120, 130) coated with a patterned photoresist (PR) and cured on a hot plate at 100°C for 2 minutes and at 180°C for 10 minutes. In an embodiment, the quantum dot may have a CdSe core and CdZnSe shell structure having a TiO ₂ ligand for conversion to a green or red color. At this time, an image analyzed by a scanning electron microscope (SEM) is as shown in (a) of FIG. 3.

Thereafter, in step (g), the photoresist-coated elastic mask layer of the remaining area of the removed elastic mask layer and the substrate on which the quantum dot layer is laminated are peeled off using an adhesive polymer. That is, the photoresist (PR)-coated elastic mask layer (120, 130) and the substrate (110) on which the cured green quantum dots (140) are laminated are peeled off using an adhesive polymer (P). In general, thicker quantum dots are required for effective color conversion, but the smaller the pattern, the lower the adhesive strength between the quantum dots and the substrate. However, the quantum dots of the present invention have a sufficiently high adhesive strength of the sidewalls to leave the quantum dot layer deposited on the substrate after the peeling process.

Finally, in step (h), only the green quantum dot pattern (140) remains on the substrate (110). In order to form a dual pattern of both green and red, a green quantum dot layer (140) is first formed and then cured. At this time, the images analyzed by a scanning electron microscope (SEM) are as shown in (b) and (c) of Fig. 3.

After that, in step (i), a passivation layer (150) is laminated before the red quantum dots are formed. That is, the passivation layer (150) is formed by using a physical chemical vapor deposition (PVD) method at room temperature to form silicon oxide (SiO ₂ ). At this time, the green quantum dot pattern (140) that has already been hardened is hardly affected. Here, the passivation layer (150) has a surface energy almost similar to that of the glass substrate (110).

Thereafter, in step (j), a red quantum dot layer (160) is laminated on an elastic mask layer (120, 130) coated with a patterned photoresist (PR) formed by repeating steps (c) to (f). That is, a red quantum dot (160) is spin-coated on an elastic mask layer (120, 130) coated with a patterned photoresist (PR) and cured on a hot plate at 100°C for 2 minutes and at 180°C for 10 minutes.

And, in step (k), the elastic mask layer (120, 130) coated with photoresist (PR) and the substrate (110) on which the cured red quantum dots (160) are laminated are peeled off using an adhesive polymer (P). This process can be represented by a shape as shown in FIG. 4. As a result, only the green quantum dot pattern (140) on which the red quantum dot pattern (160) and the passivation layer (150) are laminated remain on the substrate (110). Thereafter, the passivation layer (150) is laminated again. At this time, the image analyzed by a scanning electron microscope (SEM) is as shown in (d) of FIG. 3, and the image analyzed by an atomic force microscope (AFM) is as shown in (e). In the embodiment, the diameters of the quantum dots for green and red light conversion can be 4 nm and 7 nm, respectively.

Finally, in step (i), the substrate on which green and red quantum dot layers are laminated using a solvent-free patterning method of quantum dots is integrated into a photovoltaic device.

FIG. 5 is a diagram showing the performance results of a photoelectric device using a solvent-free patterning method of quantum dots according to one embodiment of the present invention.

Referring to FIGS. 2 and 5, (a) shows a wafer-scale full-color micro LED display having 5 μm pixels for analyzing quantum dot-integrated micro LED displays fabricated on a silicon substrate.

(b) shows a microscope image of a green and red quantum dot pattern of 10 μm pixels with a 20 μm pitch under UV light, (c) shows a microscope image of a green and red quantum dot pattern of 5 μm pixels with a 10 μm pitch under UV light, (d) shows a microscope image of a green and red quantum dot pattern sequentially patterned by a two-step process, and (e) shows a microscope image of RGB pixels for the quantum dot-integrated micro LED array.

(f) shows a schematic diagram of the quantum dot color conversion process.

The transmitted and scattered blue light constitute blue light leakage, and the downconverted light constitutes emitted green light. Additionally, some of the blue light is absorbed.

Various experiments were performed to explain the relationship between the dot matrix and the optical conversion rate.

(g) shows the PL spectra of the green and red quantum dot layers, respectively. The corresponding PL spectra and luminance values are plotted as a function of the quantum dot layer thickness, and (h) shows the absorbance of blue light from the LED as a function of the quantum dot film thickness. The absorbance was measured by subtracting the transmitted blue light power from the incident blue light power. Initial examinations showed that thicker quantum dot layers correlated with increased light conversion, but the conversion efficiency appeared to saturate as the layer thickness increased.

(i) and (j) are normalized to the intensity of absorbed blue light, emitted green light, and transmitted blue light as a function of the green quantum dot layer thickness. The external quantum efficiency (EQE) saturates with increasing quantum dot thickness. That is, the optical absorbance increases (and the light leakage decreases) with film thickness. It is important to note that this trend is not linear and saturates quickly. The combined response of absorbance, optical transmittance, and various second-order effects is denoted by the external quantum efficiency (EQE). The EQE value increases and saturates up to a certain quantum dot thickness. This result suggests that the unconverted blue light decays into different forms: scattering, re-dispersion, and absorption. Self-absorption and re-absorption phenomena between quantum dots due to the shift in the Stokes field become more prominent with increasing film thickness. Thicker films also result in a decrease in the transmittance and the fluorescence intensity of the emitted green/red light. Moreover, even though the quantum dot layer becomes thicker and the blue light leakage decreases, some of the blue light still does not reach the upper quantum dot layer. This indicates saturation of the luminescence efficiency. The EQE will quickly saturate below the internal quantum efficiency (IQE) level as the quantum dot layer thickness increases.

Meanwhile, the measurement of quantum efficiency was performed using a quantum efficiency measurement system (QE-1100, Otsuka Electronics).

(1) EQE (%) = Blue absorption (%) × IQE

(2) Blue light absorption = (total blue light power - blue light power leakage) / total blue light power

(3) IQE (i.e. conversion effectiveness) = converted red or green light power / (total blue light power - blue light power leakage)

Power values are extracted by summing the relevant spectra.

(e.g. blue = 430-490 nm)

The high-resolution GaN LED array with color conversion based on quantum dots, which are photovoltaic elements according to the present invention, has the following advantages.

First, wafer-scale self-luminous, 5 μm-sized GaN micro-LED arrays were integrated onto exogenous silicon substrates. The bonding, post-patterning techniques, and thin eutectic bonding layer used in this work allow lithographic-level alignment with higher accuracy compared to flip-chip bonding techniques.

Second, by controlling surface energy and applying an elastomeric mask, it is possible to integrate quantum dot-based color conversion layers with lithography-level resolution using a solvent-free process.

These results are a significant step forward for future displays required for HMDs, but there is still considerable room for improvement in terms of fill factor and light leakage. Application of peripheral technologies such as DBR to improve these factors will further enhance performance in the future.

Therefore, it will open the way for near-infrared displays suitable for new upcoming applications.

The present invention has been described in detail with reference to preferred embodiments illustrated in the drawings. These embodiments are not intended to limit the invention but are merely exemplary, and should be considered from an explanatory perspective rather than a restrictive perspective. The true technical protection scope of the present invention should be determined not by the above description but by the technical idea of the appended claims. Although specific terms have been used in this specification, they have been used only for the purpose of explaining the concept of the present invention and are not intended to limit the meaning or the scope of the present invention described in the claims. Each step of the present invention does not necessarily have to be performed in the order described, and may be performed in parallel, selectively, or individually. Those skilled in the art will understand that various modifications and equivalent other embodiments are possible without departing from the essential technical idea of the present invention claimed in the claims. It should be understood that equivalents include not only currently known equivalents but also equivalents to be developed in the future, that is, all components invented to perform the same function regardless of structure.

Claims (13)

Step of preparing the substrate;
A step of laminating an elastic mask layer on the above substrate;
A step of forming a pattern on the elastic mask layer;
A step of selectively removing the elastic mask layer according to the formed pattern, and surface-treating the remaining area of the removed elastic mask layer with CF ₄ plasma;
A step of laminating a quantum dot layer on the elastic mask layer that has been optionally removed; and
A method for patterning quantum dots without a solvent, comprising the step of peeling off an elastic mask layer on which the quantum dot layer is laminated using an adhesive polymer. In the first paragraph,
The steps for preparing the above substrate are:
A method for patterning quantum dots without a solvent, wherein the substrate is surface treated with oxygen plasma. In the first paragraph,
The above elastic mask layer,
A solvent-free patterning method of quantum dots, which are polymer bilayers comprising a hydrophobic polymer and an organic polymer. In the third paragraph,
The above hydrophobic polymer is,
A solvent-free patterning method of a quantum dot, comprising at least one of perfluorooctyltrichlorosilane (FOTS), octadecyltrichlorosilane (OTS), perfluorodecyltrichlorosilane (FDTS), dichlorodimethylsilane (DIMS), perfluorodecyltrichlorosilane (FTCS), dichlorodimethylsilane (DDMS), and diamond-like carbon (DLC). In paragraph 4,
The above organic polymer is,
Any of epoxy, polycarbonate (PC), polyethylene naphthalate (PEN), polynorbornene (PN), polyacrylate, polyvinyl alcohol (PVA), polyimide (PI), polyethylene terephthalate (PET), polyethersulfone (PES), polystyrene (PS), polypropylene (PP), polyethylene (PE), polyvinylchloride (PVC), polyamide (PA), polybutyleneterephthalate (PBT), polyester, polydimethylsiloxane (PDMS), and polymethylmethacrylate (PMMA). A solventless patterning method of quantum dots comprising one or more organic polymers. In paragraph 5,
The step of laminating an elastic mask layer on the above substrate is:
A solvent-free patterning method of quantum dots, which comprises drop-casting FOTS on the above substrate and then spin-coating PMMA to form the elastic mask layer. In Article 6,
The above PMMA,
A solvent-free patterning method of quantum dots dissolved in toluene. In the first paragraph,
The step of selectively removing the elastic mask layer is:
A method for patterning quantum dots without a solvent, wherein the exposed elastic mask layer is removed according to the above pattern, and the exposed elastic mask layer is removed by etching with oxygen plasma. delete In the first paragraph,
The above quantum dots
It consists of a core-shell structure.
The above core comprises at least one of CdSe, CdS, ZnS, ZnSe, CdTe, CdZnS, PbSe, AgInZnS and ZnO,
A method for solvent-free patterning of quantum dots, wherein the shell comprises at least one of CdSe, CdS, ZnS, ZnSe, CdTe, CdZnSe, PbSe, TiO, SrSe, and HgSe. In Article 10,
The above quantum dots
A solvent-free patterning method of quantum dots having a CdSe core and CdZnSe shell structure with TiO ₂ ligands. delete In the first paragraph,
After the above peeling step,
A method for patterning quantum dots without a solvent, further comprising the step of laminating a passivation layer on the substrate on which the quantum dot layer is laminated.