Dispersant, light emitting film, light emitting diode and light emitting device including the dispersant

The present disclosure relates to a dispersant having the following structure of Chemical Formula 1, a light emitting film in which the dispersant is adsorbed on a surface of an inorganic luminescent particle, and a light emitting diode and a light emitting device in which the light emitting film is applied into an emitting material layer and/or a color conversion film. The dispersant enables the inorganic luminescent particle to have excellent dispersion property and optical properties, and thus the light emitting diode and the light emitting device can its luminous efficiency and luminous lifetime.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(a) to Republic of Korea Patent Application No. 10-2019-0121691, filed in Republic of Korea on Oct. 1, 2019, the entire contents of which are incorporated herein by reference into the present application.

BACKGROUND

Technical Field

The present disclosure relates to a dispersant, and more particularly, to a dispersant that improves dispersion properties and thermal resistance of an inorganic luminescent particle, a light emitting film, a light emitting diode and a light emitting device including the dispersant.

Discussion of the Related Art

As the information communication technologies and electronics technologies have developed, various flat display devices in place of the conventional CRT have been proposed. Among those flat display devices, a liquid crystal display (LCD) device, an organic light-emitting diode (OLED) display device and a quantum-dot light emitting diode (QLED) display device, each of which can realize thinner and lighter weight compared to the CRT, has been in the spotlight.

Since the liquid crystal panel cannot emit light by itself, the use of an external backlight unit serving as a light source is essential. Compared to the LCD device, each of the OLED and QLED devices can be fabricated with more thinness and light weight. Also, each of the OLED and QLED has advantages in terms of power consumption, and thus has low driving voltages and fast response speed compared to the LCD. In addition, each of the OLED and QLED can be fabricated using simple process, there is an advantage that the production const can be much reduced than the LCD.

The OLED or the QLED comprises a red EML, a green EML and a blue EML for each of a red pixel region, a green pixel region and a blue pixel region, and emits red (R), green (G) and blue (B) lights to implement full-color images. Recently, an OLED or QLED display device having red/green/blue/white structures that forms a light emitting diode emitting white (W) light over the whole pixel region and adopts a color filter layer has been mainly used.

Since considerable amount of white light emitted from the OLED or the QLED in the conventional OLED or QLED display device is adsorbed in the color filter layer, luminous efficiency is deteriorated. Since the color filter layer that is formed correspondingly to the red, green and blue pixel regions in the OLED and the QLED display devices transmits light with specific wavelengths and absorbs light with other wavelengths, the luminous efficiency is greatly reduced. In addition, a quantum dots as inorganic luminescent particles are vulnerable to oxygen or moisture, and have poor thermal resistance. When manufacturing or using a light emitting display device including the quantum dots, the quantum dots exposed to outside air or moisture deteriorates, and the luminous efficiency and luminous lifetime of the devices deteriorates. Moreover, since the quantum dots has bad dispersion properties for the solvents, there exists a limit to use only specific type solvent when forming the quantum dot film in a solution process.

SUMMARY

Accordingly, embodiments of the present disclosure are directed to a dispersant, and a light-emitting apparatus such as a light-emitting film, a light emitting diode, a light emitting device including the dispersant that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.

An aspect of the present disclosure is to provide a dispersant having excellent dispersion properties and can enhance thermal resistances of a luminescent particle, a light emitting film, a light emitting diode and a light emitting device including the dispersant.

Another aspect of the present disclosure is to provide a dispersant that can improvise luminous efficiency and luminous lifetime of the luminescent particle, a light emitting film, a light emitting diode and a lithe emitting device including the dispersant.

To achieve these and other aspects of the inventive concepts, as embodied and broadly described, the present disclosure provides a dispersant having the following Chemical Formula 1:

wherein R1is an unsubstituted or substituted C2-C20alkylene group, an unsubstituted or substituted C2-C20alkyl vinylene group, an unsubstituted or substituted C6-C30arylene group or an unsubstituted or substituted C3-C30hetero arylene group; R2is an unsubstituted or substituted C1-C20alkylene group, an unsubstituted or substituted C5-C20cyclo alkylene group, an substituted or substituted C6-C20arylene group, a C10-C30bicyclo alkylene group or a C12-C30biarylene group, wherein each of the C10-C30bicyclo alkylene group and the C12-C30biarylene group is linked to a C1-C5alkylene group; R3is a C5-C20aliphatic hydrocarbon; R4is protium, deuterium or a C1-C10alkyl group; and each of m and n is independently an integer of 1 to 100.

In another aspect, the present disclosure provides a light emitting film comprises an inorganic luminescent particle and a dispersant having the structure of Chemical Formula 1 and adsorbed on a surface of the inorganic luminescent particle.

In still another aspect, the present disclosure provides an inorganic light emitting diode (LED) that comprises a first electrode, a second electrode facing the first electrode, and an emitting material layer disposed between the first and second electrodes, wherein the emitting material layer comprises an inorganic luminescent particle and the dispersant adsorbed on a surface of the inorganic luminescent particle.

In further still another aspect, the present disclosure provides an inorganic light emitting device comprises a substrate and an inorganic emitting diode as defined above.

In further still another aspect, the present disclosure provides a light emitting device comprises a substrate, a light emitting diode over the substrate and a color conversion layer disposed between the substrate and the light emitting diode or over the light emitting diode, wherein the color conversion layer converts a light emitted from the light emitting diode to other colors, and wherein the color conversion layer comprises an inorganic luminescent particle and the dispersant adsorbed on a surface of the inorganic luminescent particle.

DETAILED DESCRIPTION

Reference and discussion will now be made below in detail to aspects, embodiments and examples of the disclosure, some examples of which are illustrated in the accompanying drawings.

An inorganic luminescent particle such as a quantum dot (QD) or a quantum rod (QR) has been applied into a solution process such as an inkjet printing process as well as a photo-resist (PR) process. To this end, it is important to select a material suitable for the printing process or to apply a material having a high refractive index such as TiO2to the inorganic luminescent particles in order to improve the transmittance and enhance the recycle effect for excitation light emitted from the particles. Particularly, when the inorganic luminescent particles are dispersed in the ink-type composition, there is a high interest in thermally curable type materials and photo-curable materials such as UV-curable materials. Accordingly, it is necessary to develop materials suitable for the ink-type composition in order to optimize the performances of the inorganic luminescent particles.

The thermally curable ink generally comprises the inorganic luminescent particles, a polymer, a high refractive index material and a solvent, and the contents of the inorganic luminescent particles in the ink is typically about 30 wt %. A thermally curable film containing the inorganic luminescent particles usually has a thickness of 6 um or more, and there is a problem in that the luminous efficiency of the inorganic luminescent particles is lowered by a plastic working process. On the other hand, the photo-curable ink cured by light such as UV includes the inorganic luminescent particles, a polymer and a high refractive index material. The photo-curable film should have a thickness of at least 10 um, but the contents of the inorganic luminescent particles are low since there is no solvent, which limits the luminous efficiency.

Also, the conventional polyurethane-based dispersant applied as an ink-type lacks solvent-compatible sites. Therefore, the convention polyurethane-based dispersant can be dispersed only in a non-polar solvent such as toluene (refractive index n is 1.4965, dielectric constant ε is 2.38), hexane (n is 1.375, ε is 1.89), but cannot dispersed in a polar solvent such as propylene glycol monomethyl ether (PGMEA; n is 1.40, ε is 8.3). Accordingly, when a solution process such as an ink jet printing process is applied to form a thin film of inorganic luminescent particles, a type of solvent that can be used is limited.

In addition, since the conventional polyurethane-based dispersant consists of a linear backbone or main chain, it is difficult to prevent the adjacent inorganic luminescent particles from agglomerating or aggregating with each other even if the conventional polyurethane-based dispersant adsorbs to the inorganic luminescent particles. In this case, while the donor inorganic luminescent particles are disposed close to predetermined distance from adjacent acceptor inorganic luminescent particles, light emitted from the donor inorganic luminescent particles is absorbed by the acceptor inorganic luminescent particles. Accordingly, the light energy emitted from the donor inorganic luminescent particles does not induce luminescence of the donor inorganic luminescent particles, but excites adjacent acceptor inorganic luminescent particles to induce FRET (Forster/Fluorescence Resonance Energy Transfer) of the acceptor inorganic luminescent particles, and therefore the light energy is lost. The inorganic luminescent particles have deteriorated quantum yield (QY) due to such self-quenching mechanism. Moreover, when the inorganic luminescent particles such as QD are exposed continuously to high temperature, the ligand bound to the surface on the inorganic luminescent particles is detached or separated from the particles, or the core/shell of the particles are oxidized, resulting in a rapidly deteriorated luminous properties of the particles.

In one aspect, the present disclosure relates to a polyurethane-based dispersant having a Host-Guest molecular conformation that can be utilized in a dispersion composition such as a thermally curable ink including inorganic luminescent particles. A pillar structure introduced as a guest within the dispersant enables the inorganic luminescent particles to be dispersed in a polar solvent as well as a non-polar solvent. In addition, since the pillar structure having a predetermined length can prevent the adjacently disposed inorganic luminescent particles from agglomerating, quantum efficiency deterioration due to FREM between adjacently disposed inorganic luminescent particles can be prevented.

Moreover, as the dispersant having the pillar structure encapsulates the inorganic luminescent particles, the inorganic luminescent particles exposed to high temperature can improve its thermal resistance. In other words, it is possible to disperse the inorganic luminescent particles in a polar solvent, to prevent the quantum efficiency of the particles from deteriorating, and to secure the thermal resistance which is required during the film formation process using the ink-type composition having the particles, by dispersing the inorganic luminescent particles in the dispersant of the present disclosure. The dispersant of the present disclosure has the following structure of Chemical Formula 1:

In Chemical Formula 1, R1is an unsubstituted or substituted C2-C20alkylene group, an unsubstituted or substituted C2-C20alkyl vinylene group, an unsubstituted or substituted C6-C30arylene group or an unsubstituted or substituted C3-C30hetero arylene group; R2is an unsubstituted or substituted C1-C20alkylene group, an unsubstituted or substituted C5-C20cyclo alkylene group, an substituted or substituted C6-C20arylene group, a C10-C3o bicyclo alkylene group or a C12-C30biarylene group, wherein each of the C10-C3o bicyclo alkylene group and the C12-C3o biarylene group is linked to a C1-C5alkylene group; R3is a C5-C20aliphatic hydrocarbon; R4is protium, deuterium or a C1-C10alkyl group; and each of m and n is independently an integer of 1 to 100.

As used herein, the term “unsubstituted” means that hydrogen is linked, and in this case, hydrogen comprises protium, deuterium and tritium.

As used the term “substituted” herein, the substitution group comprises, but is not limited to, unsubstituted or halogen-substituted C1-C20alkyl, unsubstituted or halogen-substituted C1-C20alkoxy, halogen, cyano, —CF3, a hydroxyl group, a carboxylic group, a carbonyl group, an amino group, a C1-C10alkyl amino group, a C6-C30aryl amino group, a C3-C30hetero aryl amino group, a C6-C30aryl group, a C3-C30hetero aryl group, a nitro group, a hydrazyl group, a sulfonate group, a C1-C20alkyl silyl group, a C6-C30aryl silyl group and a C3-C30hetero aryl silyl group.

As used herein, the term “hetero” in such as “a hetero aromatic ring”, “a hetero cycloalkyene group”, “a hetero arylene group”, “a hetero aryl alkylene group”, “a hetero aryl oxylene group”, “a hetero cycloalkyl group”, “a hetero aryl group”, “a hetero aryl alkyl group”, “a hetero aryloxyl group”, “a hetero aryl amino group” means that at least one carbon atom, for example 1-5 carbons atoms, constituting an aromatic ring or an alicyclic ring is substituted at least one hetero atom selected from the group consisting of N, O, S, P and combination thereof.

In one exemplary aspect, each of the C2-C20alkylene group, the C2-C20alkyl vinylene group, the C6-C30arylene group and the C3-C30hetero arylene group in R1may be independently unsubstituted or substituted with at least one of a C1-C20alkyl amino group, an ether (—O) group, an ester group (—COO—), a carbonate group (—OCCO—), a C3-C20alkyl (meth) acrylate group and a C3-C20alkyl (meth) acrylic acid group. In addition, each of the C5-C20cyclo alkylene group and the C6-C20arylene group in R2may be unsubstituted or substituted with a C1-C10alkyl group. As used herein, each of the term (meth) acrylate refers to acrylate and methacrylate, and the term (meth) acrylic acid refers to acrylic acid and methacrylic acid as indicated otherwise.

As indicated in Chemical Formula 1, the polyurethane-based dispersant can disperse better the inorganic luminescent particles compared to acryl-based or polyester-based dispersants. Particularly, the polyurethane-based dispersant can solve the issues of decreasing of the quantum yield (QY) and external quantum efficiency (EQE) of the inorganic luminescent particles involved in the high-temperature heat treatment process before and after the film forming process using the ink-type composition containing the particle.FIG.1is a schematic diagram illustrating synthesis scheme of a dispersant in one exemplary aspect of the present disclosure and illustrates polyethylene glycol (PEG) as an alcohol precursor and 1,6-hexamethylene diisocyanate (HDI) as an isocyanate precursor.FIG.2is a schematic diagram illustrating a mechanism of dispersing an inorganic luminescent particle a dispersant in accordance of the present disclosure.

As illustrated inFIG.1, an alkanediol as a guest is added to a host that is an alcohol precursor and an ioscyanate precursor constituting the polyurethane backbone or main chain. Accordingly, a host-guest type polyurethane-based dispersant having an extended pillar structure derived from the guest alkanediol as a side chain of the polyurethane main chain is synthesized.

The pillar structure constituting the side chain of the polyurethane main chain does not act as a branching or bridge for extending the main chain, but as a threshold or a barrier to improve or enhance the dispersion properties of the inorganic luminescent particles and to prevent the particles from agglomerating. To this end, the alkanediol added to form the pillar structure may be 1,1-alkanediol, and the pillar structure as the side chain may be introduced into the polyurethane main chain using a host-guest reaction.

When 1,1-alkanedio is added in synthesizing the dispersant, the hydrogen atom of the hydroxyl group linked to the 1stposition of the 1,1-alkandiol is reacted with the nitrogen atom of the isocyanate group forming the urethane bond, and the oxygen atom of 1,1-alkanediol is bonded to the carbonyl group to form the extended pillar structure as the side chain of the polyurethane main chain. In this case, the aliphatic chain, which forms the pillar structure inserted in the linear polyurethane main chain, has an anti-conformational structure.

As illustrated inFIGS.1and2, the extended pillar structure154in the dispersant150does not cover an adjacently positioned amino group154that can be adsorbed or anchored on a surface of the inorganic luminescent particles, in the polyurethane main chain152. In one exemplary aspect, R3in Chemical Formula 1, which corresponds to the pillar structure154, may comprise, but is not limited to, a C5-C20aliphatic hydrocarbon, for example, a C5-C18alkyl group, preferably a C7-C18linear alkyl group (InFIG.1, the number of k is 4-17, preferably 6-17).

If the number of the carbon atom in R3is less than five, the length of the pillar structure154adsorbed on the surface of the inorganic luminescent particle150is too short to prevent the agglomeration of the inorganic luminescent particle150. In addition, since the length of the pillar structure150is not sufficient to protect the inorganic luminescent particle150from external influences such as heat, oxygen and moisture, the thermal resistance and dispersion properties of the inorganic luminescent particle150may be deteriorated.

On the contrary, if the number of the carbon atom in R3exceeds 20, a defect may occur in the aliphatic hydrocarbon, and the pillar structure154may from a Gauche conformation or a twisted oriented structure, kink conformation, not an anti-conformation, by the external influence, i.e. external forces, therefore does not form a stable pillar structure154. When the aliphatic hydrocarbon constituting the pillar structure154forms the Gauche conformation or the kink conformation, the bonding angle between the pillar structure154and polyurethane main chain152decreases, and the pillar structure154may cover the adjacently positioned amino group156. Accordingly, the dispersion properties and the thermal resistance of the inorganic luminescent particle100may be deteriorated as the pillar structure154covers a space at which the dispersant150adsorbs to the inorganic luminescent particle100.

For example, when 1,2-alkanediol, 1,3-alkanediol and/or 1,ω-diol are added as guests, a geometrical resistance between the polyurethane main chain152, which prefers a linear structure with regard to an orientation of the polyurethane, and the aliphatic hydrocarbon constituting the pillar structure154is occurred. In this case, strain occurs between those chains, and the resulting strain causes stress in the whole dispersant molecular structure. The stress within the dispersant molecule150shifts from the polyurethane main chain152to the pillar structure154, and the aliphatic hydrocarbon chain constituting the pillar structure154forms Gauche conformation or kink conformation, not anti-conformation.

The dispersant150of the present disclosure has the sable pillar structure154in which an aliphatic side chain derived from 1,1-diol is elongated without extending the urethane backbone. The stable pillar structure154acts as a site compatible with an organic solvent, thus the inorganic luminescent particle100dispersed in the dispersant150can be stably dispersed in a polar solvent as well as a non-polar solvent.

Since the long-extending aliphatic side chain of the polyurethane does not cover the site absorbed on the surface of the inorganic luminescent particle100, it can stably absorb and anchor on the surface of the inorganic luminescent particle. The pillar structure154induce a sterical hindrance effect, thus the inorganic luminescent particle100is spaced apart from each other at least the length of the pillar structure154. Since the distance between adjacently dispersed inorganic luminescent particles100cannot be too close due to the long elongated aliphatic side chain, it is possible to minimize FRET phenomenon in which energy transfer between adjacently dispersed inorganic luminescent particles100. Also, the inorganic luminescent particles100does not show any decrease in luminous efficiency due to the FRET. As the dispersant150adheres strongly on the surface of the inorganic luminescent particle100, it is possible to minimize contact external oxygen or moisture with the inorganic luminescent particles. In addition, as the dispersant150encapsulates the inorganic luminescent particle100, the dispersant150protects the inorganic luminescent particle100in high temperature environment, so that the inorganic luminescent particle100can improve its thermal resistance property. By dispersing the inorganic luminescent particle100in the dispersant150, the inorganic luminescent particle can maintain its luminous efficiency and luminous lifetime even when the inorganic luminescent particles100are exposed to external air or moisture or in the high temperature environment. Therefore, the dispersant may be applied to a light emitting film, a LED package, a color conversion film and a light emitting diode each of which requires excellent luminescent properties.

The polyurethane main chain152may be derived from an alcohol precursor and an isocyanate precursor. For example, each of R1and R4may be independently derived from an alcohol-based precursor having at least one hydroxyl group. As an example, the alcohol-based precursor may comprise, but is not limited to, polyether-based alcohols based on propylene oxides or ethylene oxides; aliphatic polyester-based alcohols; aromatic polyester-based alcohols; polyether-based alcohols based on tetrahydrofuran (THF); polycarbonate-based alcohols; acryl-based alcohol; and alkenyl-based alcohols such as polybutadiene.

For example, the polyether-based alcohols may be synthesized through addition reaction of ethylene oxide or propylene oxide and alcohol or amine initiator in the present of an acid or base catalyst. The polyester-based alcohol may be synthesized by a condensation reaction of glycols (ex. ethylene glycol, 1,4-butanediol, 1,6-hexanediol) and an aliphatic or aromatic dicarboxylic acid/anhydride. The acryl-based alcohols may be synthesized by free radical polymerization process that reacting hydroxyethyl (meth) acrylate with other acrylic compounds.

As an example, R1in Chemical Formula 1 may comprise, but is not limited to, a C3-C10alkylene group unsubstituted or substituted with at least one group selected from a C1-C10alkyl amino group such as an amino methyl group, an amino ethyl group, an amino propyl group and an amino butyl group, an ether group, an ester group, a carbonated group, a C3-C10alkyl (meth) acrylate group such as a methyl (meth) acrylate group and an ethyl (meth) acrylate group, and C3-C30alkyl (meth) acrylic acid group; C2-C10alkyl vinylene group; a C6-C10arylene group unsubstituted or substituted with at least one group selected from a C1-C10alkyl amino group such as an amino methyl group, an amino ethyl group, an amino propyl group and an amino butyl group, an ether group, an ester group, a carbonated group, a C3-C10alkyl (meth) acrylate group such as a methyl (meth) acrylate group and an ethyl (meth) acrylate group, and C3-C30alkyl (meth) acrylic acid group; and C3-C10hetero arylene group unsubstituted or substituted with at least one group selected from a C1-C10alkyl amino group such as an amino methyl group, an amino ethyl group, an amino propyl group and an amino butyl group, an ether group; an ester group, a carbonated group, a C3-C10alkyl (meth) acrylate group such as a methyl (meth) acrylate group and an ethyl (meth) acrylate group, and C3-C30alkyl (meth) acrylic acid group.

As an example, R2in Chemical Formula 1 may comprise, but is not limited to, a C1-C10alkylene group, an unsubstituted or C1-C5alkyl substituted C5-C20cyclo alkylene group, an unsubstituted or C1-C5alkyl substituted C6-C10arylene group, a C10-C20bicyclo alkylene group linked to a C1-C3alkylene group (ex. C2-C3alkylene group) and a C10-C20biarylene group linked to a C1-C3alkylene group (ex. C2-C3alkylene group). For Example, R2in Chemical Formula 1 may be a C2-C10alkylene group, preferably a C5-C10alkylene group.

In one exemplary aspect, the polyurethane-based dispersant having the structure of Chemical Formula 1 may have a weigh average molecular weight (MW), but is not limited to, between about 2,000 and about 50,000, preferably between about 2,000 and about 10,000. When the polyurethane-based dispersant has the weight average molecular weight within the ranges above, it can stably adsorb on the surface of the inorganic luminescent particle100and exhibit intended functions.

The inorganic luminescent particle100that can be dispersed in the polyurethane-based dispersant150may comprise a quantum dot (QD) a quantum rod (QR). As an example, when the inorganic luminescent particle100receives primary light emitted from a light source, electrons becomes an excited state from a ground state, and emits photons when falling from the excited state to the ground state, and emits secondary light with different wavelength bands. Alternatively, the inorganic luminescent particle100can form excitons excited by charge carriers such as holes and electrons, respectively, generated from two opposite electrodes in the light emitting diode D, D1(see,FIGS.8and9), and then emit light with predetermined wavelength bands.

Inorganic luminescent particle100such as QDs or QRs are inorganic luminescence particle which emits light as unstable charge excitons shifts from the conduction band energy level to the valance band energy level. These inorganic luminescence particles100have very large extinction coefficient, high quantum yield among inorganic particles and generates strong fluorescence. In addition, these inorganic luminescence particles100emits at different luminescence wavelengths as its sizes, it is possible to emit lights within the whole visible light spectra so as to implement various colors by adjusting sizes of these inorganic luminescence particles100

In one exemplary aspect, the inorganic luminescent particle100may have a single-layered structure. In another exemplary aspect, the inorganic luminescent particle100may have a multiple-layered heterologous structure, i.e. a core110, a shell120enclosing the core110. The inorganic luminescent particle100may comprise plural ligands130bound to a surface of the shell120.

Each of the core110and the shell120may have a single layer or multiple layers, respectively. The reactivity of precursors forming the core110and/or shell120, injection rates of the precursors into a reaction vessel, reaction temperature and kinds of ligand130bonded to the outer surface of those inorganic luminescence particles100may have affects upon the growth degrees, crystal structures of those inorganic luminescence particles100. As a result, it is possible to emit lights of various luminescent wavelength ranges, as the energy level bandgap of those inorganic luminescence particles100are adjusted.

In one exemplary aspect, inorganic luminescence particles100(e.g. QDs and/or QRs) may have a type I core/shell structure where an energy level bandgap of the core110is within an energy level bandgap of the shell120. In case of using the type I core/shell structure, electrons and holes are transferred to the core110and recombined in the core110. Since the core110emits light from exciton energies, it is possible to adjust luminance wavelengths by adjusting sizes of the core310.

In another exemplary aspect, the inorganic luminescence particles100(e.g. QDs and/or QRs) may have type II core/shell structure where the energy level bandgap of the core110and the shell120are staggered and electrons and holes are transferred to opposite directions among the core110and the shell120. In case of using the type II core/shell structure, it is possible to adjust luminescence wavelengths as the thickness and the energy bandgap locations of the shell120.

In still another exemplary aspect, the inorganic luminescence particles100(e.g. QDs and/or QRs) may have reverse type I core/shell structure where the energy level bandgap of the core110is wider than the energy level bandgap of the shell320. In case of using the reverse type I core/shell structure, it is possible to adjust luminescence wavelengths as thickness of the shell120.

As an example, when the inorganic luminescence particle100(e.g. QDs and/or QRs) has a type-I core/shell structure, the core110is a region where luminescence substantially occurs, and a luminescence wavelength of the inorganic luminescence particle100is determined as the sizes of the core110. To achieve a quantum confinement effect, the core110necessarily has a smaller size than the exciton Bohr radius according to material of the inorganic luminescence particle300, and an optical bandgap at a corresponding size.

The shell120of the inorganic luminescence particles100(e.g. QDs and/or QRs) promotes the quantum confinement effect of the core110, and determines the stability of the particles100. Atoms exposed on a surface of colloidal inorganic luminescence particles100(e.g. QDs and/or QRs) having only a single structure have lone pair electrons which do not participate in a chemical bond, unlike the internal atoms. Since energy levels of these surface atoms are between the conduction band edge and the valance band edge of the inorganic luminescence particles100(e.g. QDs and/or QRs), the charges may be trapped on the surface of the inorganic luminescence particles100(e.g. QDs and/or QRs), and thereby resulting in surface defects. Due to a non-radiative recombination process of excitons caused by the surface defects, the luminous efficiency of the inorganic luminescence particles100may be degraded, and the trapped charges may react with external oxygen and compounds, leading to a change in the chemical composition of the inorganic luminescence particles100, or to a permanent loss of the electrical/optical properties of the inorganic luminescence particles100.

To effectively form the shell120on the surface of the core110, a lattice constant of the material in the shell120needs to be similar to that of the material in the core110. As the surface of the core110is enclosed by the shell120, the oxidation of the core110may be prevented, the chemical stability of the inorganic luminescence particles100(e.g. QDs and/or QRs) may be enhanced, and the photo-degradation of the core110by an external factor such as water or oxygen may be prevented. In addition, the loss of excitons caused by the surface trap on the surface of the core110may be minimized, and the energy loss caused by molecular vibration may be prevented, thereby enhancing the quantum efficiency.

In one exemplary aspect, each of the core110and the shell120may include, but is not limited to, a semiconductor nanocrystal and/or metal oxide nanocrystal having quantum confinement effect. For example, the semiconductor nanocrystal of the core110and the shell120may be selected from the group, but is not limited to, consisting of Group II-VI compound semiconductor nanocrystal, Group III-V compound semiconductor nanocrystal, Group IV-VI compound semiconductor nanocrystal, Group I-III-VI compound semiconductor nanocrystal and combination thereof.

Group IV-VI compound semiconductor nanocrystal of the core110and/or shell120may be selected from the group, but is not limited to, consisting of TiO2, SnO2, SnS, SnS2, SnTe, PbO, PbO2, PbS, PbSe, PbTe, PbSnTe and combination thereof. Also, Group I-III-VI compound semiconductor nanocrystal of the core110and/or shell120may be selected from the group, but is not limited to, AgGaS2, AgGaSe2, AgGaTe2, AgInS2, CuInS2, CuInSe2, Cu2SnS3, CuGaS2, CuGaSe2and combination thereof. Alternatively, each of the core110and the shell120may independently include multiple layers each of which has different Groups compound semiconductor nanocrystal, e.g., Group II-VI compound semiconductor nanocrystal and Group III-V compound semiconductor nanocrystal such as InP/ZnS, InP/ZnSe, GaP/ZnS, and the likes, respectively.

In another aspect, the metal oxide nanocrystal of the core110and/or shell120may include, but are not limited to, Group II or Group III metal oxide nanocrystal. As an example, the metal oxide nanocrystal of the core310and/or the shell320may be selected from the group, but is not limited to, MgO, CaO, SrO, BaO, Al2O3and combination thereof.

The semiconductor nanocrystal of the core110and/or the shell120may be doped with a rare earth element such as Eu, Er, Tb, Tm, Dy or an arbitrary combination thereof or may be doped with a metal element such as Mn, Cu, Ag, Al or an arbitrary combination thereof.

In another exemplary aspect, the inorganic luminescence particle100may include, but are not limited to, alloy QD or alloy QR such as homogenous alloy QD or QR or gradient alloy QD or QR, e.g. CdSxSe1-x, CdSexTe1-x, CdXZn1-xS, ZnxCd1-xSe, CuxIn1-xS, CuxIn1-xSe, AgxIn1-xS.

The ligand130bound to the surface of the shell120is not particularly limited. In one exemplary aspect, the ligand133may be an organic ligand having a negative charge (−), that is, an X-type ligand at one or more terminals thereof. For example, the X-type ligand may have a negatively charged group selected from the group consisting of a carboxylate group (—COO−), a phosphonate group (—P(OR)3) and a thiolate group (—RS) (for example, R is hydrogen, C1-C20aliphatic hydrocarbon, C6-C30aromatic group or a C3-C30hetero aromatic group). For example without limitation, the X-type ligand130having the negative charge may be bound to the surface of the shell120though the terminal carboxylate group. In this case, the negatively charged group, for example, the carboxylate group, in the X-type ligand130may electrically interact with the metal constituting the shell120.

As an example, the ligands130having the terminal carboxylate group may be derived from, but is not limited to, a saturated or unsaturated C5-C30aliphatic carboxylic acid, preferably a saturated or unsaturated C8-C20aliphatic carboxylic acid. More particularly, the ligand130having the terminal carboxylate group may be derived from a saturated or unsaturated aliphatic carboxylic acid such as octanoic acidCH3(CH2)6COOH), decanoic acid (CH3(CH2)8COOH), dodecanoic acid (or lauric acid, CH3(CH2)10COOH), 1-tetradicanoic acid(or myristic acid, CH3(CH2)12COOH), n-hexadecanoic acid (or palmitic acid, CH3(CH2)14COOH), n-octadecanoic acid (or stearic acid, CH3(CH2)16COOH), cis-9-octadecenoic acid (or oleic acid, CH3(CH2)7CH═CH(CH2)7COOH).

In an alternative aspect, the ligands130may be an organic ligand bound to the surface of the metal constituting the shell120through lone pair electrons, that is, an L-type ligand. The organic ligands130having the lone pair electrons may interact with the metal component constituting the shell120by coordinating with the metal component through the lone pair electrons of the group selected from an amino group (—NR2), a thiol group (—SH), a phosphine group (—PR) and a phosphine oxide group (—POR) (for example, R is hydrogen, C1-C20aliphatic hydrocarbon, C6-C30aromatic group or a C3-C30hetero aromatic group). As an example, when the organic ligand133has a terminal amino group including the lone pair electrons, the nitrogen atom in the amino group is strongly bonded to the metal component of the shell120by the coordination bonds between the nitrogen atom and the metal component.

For example, the organic ligand133having the lone pair electrons may be selected from, but is not limited to, C1-C10alkyl amine (e.g. primary, secondary or tertiary alkyl amine), preferably linear or branched C1-C5alkyl amine; C4-C8alicyclic amine, preferably C4-C8alicyclic amine; C5-C20aromatic amine, preferably C5-C10aromatic amine; linear or branched C1-C10alkyl phosphine (e.g. primary, secondary or tertiary alkyl phosphine), preferably linear or branched C1-C5alkyl phosphine; linear or branched C1-C10alkyl phosphine oxide (e.g. primary, secondary or tertiary alkyl phosphine oxide), preferably linear or branched C1-C5alkyl phosphine oxide and combination thereof.

In one exemplary aspect, the organic ligand130having the lone pair electrons may comprise, but is not limited to, tertiary amines such as tris(2-aminoethy)amine (TAEA) and tris(2-aminomethyl)amine; alkyl polyamines such as N-butyl-N-ethylethane-1,2-diamine, ethylene diamine and pentaethylenehexamine); alicyclic amines such as cyclohexane-1,2-diamine and cyclohexene-1,2-diamine; aromatic amines 2,3-diaminopyridine; and combination thereof.

[Light Emitting Film, LED package and Liquid Crystal Display Device]

As described above, the polyurethane-based dispersant150enables the inorganic luminescent particle100to improve its dispersion properties, thermal resistance and luminous properties. The inorganic luminescent particle100dispersed in the polyurethane-based dispersant can be applied into various light emitting apparatuses. We will now describe a light emitting film, an LED package and a display device that can be fabricated from the composition including the inorganic luminescent particle100dispersed in the polyurethane-based dispersant.

FIG.3is a cross-sectional view schematically illustrating the structure of a light emitting film in accordance with an exemplary aspect of the present disclosure where the light emitting film comprises inorganic luminescent particles and the dispersants. As illustrated inFIG.3, the light emitting film200comprises the dispersant150adsorbed on a surface of the inorganic luminescent particle100. The inorganic luminescent particle100may comprise a quantum dot or a quantum rod having the heterologous structure of the core110and the shell120. As an example, the inorganic luminescent particle100can implement various colors by adjusting the kinds and sizes of the core110, and can reduce trap energy level by using the shell120that protects the core110. While shown inFIG.3, the dispersant150includes the extended pillar structure154(see,FIG.2) as the side chain of the polyurethane main chain152(see,FIG.2) and an adsorbed site156(see,FIG.2) positioned adjacently to the pillar structure154and anchored to the surface of the inorganic luminescent particle100in the polyurethane main chain152.

As the polyurethane-based dispersant150having the pillar structure154is adsorbed to the surface of the inorganic luminescent particle100, the inorganic luminescent particle100can improve its dispersion properties and can minimize the deterioration of the thermal resistance and luminous efficiency. For example, the light emitting film200may comprise, but is not limited to, the inorganic luminescent particle100between about 20 parts by weight and between 30 parts by weight, and the polyurethane-based dispersant150between about 30 parts by weight and about 50 parts by weight. As used herein, the term ‘part by weight’ indicates a relative weight ratio among the mixed components.

The light emitting film200may further comprises a binder220. As an example, the binder220may comprise, but is not limited to, epoxy resin and/or a silicone resin having excellent thermal resistance property. The contents of the binder220in the light emitting film200may be between about 20 parts by weight and about 50 parts by weight.

FIG.4is a cross-sectional view schematically illustrating a display device in accordance with an exemplary aspect of the present disclosure where the display device comprises inorganic luminescent particles and the dispersants applied in the light emitting film.FIG.5is a cross-sectional view schematically illustrating a display panel constituting the display device in accordance with another exemplary aspect of the present disclosure.

As illustrated inFIG.4, a liquid crystal display (LCD) device300comprises a liquid crystal panel302, a backlight unit390disposed under the liquid crystal panel302, and a light-emitting film200disposed between the liquid crystal panel302and the backlight unit390. The light emitting film200may comprise the dispersant150adsorbed to the surface of the inorganic luminescent particle100and the binder200.

With referring toFIG.5, the liquid crystal panel302includes first and second substrates310and370, and a liquid crystal layer360interposed between the first and second substrates310and370and including liquid crystal molecules362. The first substrate310may be made of transparent materials, and may be, but is not limited to, a glass substrate, a thin flexible substrate or a polymeric plastic substrate. The second substrate370may be made of transparent or obscured materials. For example, the second substrate370may be made of glass, plastics such as polyimide, metal foil, and the like.

A gate electrode320is formed on the first substrate310, and a gate insulating layer322is formed to cover the gate electrode320. In addition, a gate line (not shown) connected to the gate electrode320is formed on the first substrate310. The gate insulating layer322may be made of inorganic material such as silicon oxide (SiOx) and/or silicon nitride (SiNx)

On the gate insulating layer320, a semiconductor layer330is formed to correspond to the gate electrode320. The semiconductor layer330may consist of an oxide semiconductor material. However, the semiconductor layer330may include an active layer consisting of amorphous silicon and an ohmic contact layer consisting of amorphous silicon with impurities.

On the semiconductor layer330, a source electrode344and a drain electrode346are formed to be spaced apart from each other. In addition, a data line (not shown) connected to the source electrode344intersects with the gate line to define a pixel area. The gate electrode320, the semiconductor layer330, the source electrode344and the drain electrode346constitute a thin film transistor Tr.

On the thin film transistor Tr, a passivation layer350having a drain contact hole352exposing the drain electrode346is formed. The passivation layer350may be made of inorganic insulating material such as silicon oxide (SiOx) and silicon nitride (SiNx) and/or organic insulating material such as benzocyclobutene or photo-acryl. On the passivation layer350, a pixel electrode340, which is a first electrode connected to the drain electrode346by a drain contact hole352, and a common electrode342which is a second electrode alternately arranged with a pixel electrode340, are formed.

Meanwhile, a black matrix382covering a non-display region which includes the thin film transistor Tr, the gate line, the data line, etc. is formed on the second substrate370. In addition, color filter layers380are formed to correspond to pixel areas.

The first and second substrates310and370are combined to have the liquid crystal layer360disposed between them, and the liquid crystal molecules362of the liquid crystal layer360are driven by an electric field generated between the pixel electrode340and the common electrode342. Although not shown inFIG.5, an alignment layer may be formed in contact with the liquid crystal layer360on each of the first and second substrates310and370, and polarizers having transmission axes perpendicular to each other may be attached to the outer surfaces of the first and second substrates310and370, respectively.

Referring back toFIG.4, the backlight unit390includes a light source (not shown) and provides light to the liquid crystal panel302. The backlight unit390may be classified into a direct type and a side type according to the position of a light source. When the backlight unit390is of a direct type, the backlight unit390may include a bottom frame (not shown) covering the lower part of the liquid crystal panel302and a plurality of light sources may be arranged on a horizontal surface of the bottom frame. Meanwhile, when the backlight unit390is of a side type, the backlight unit390may include a bottom frame (not shown) covering the lower part of the liquid crystal panel302, a light guide plate (not shown) may be disposed on the horizontal surface of the bottom frame, and light sources may be disposed on at least one part of the light guide plate. Here, the light source may emit light at a wavelength range of blue light, for example, within a wavelength ranging from approximately 430 to 470 nm.

The light emitting film200may be disposed between the liquid crystal panel302and the backlight unit390, and enhance a color purity of light provided by the backlight unit390. For example, the light emitting film200may include the polyurethane-based dispersant150adsorbed to the surface of the inorganic luminescent particle100such as a quantum dot and/or a quantum rod and the binder200enclosing the inorganic luminescent particle100and the dispersant150.

Now, an LED package to which the composition including the dispersant adsorbed to the inorganic luminescent particle is applied will be described.FIG.6is a cross-sectional view schematically illustrating a display device in accordance with another exemplary aspect of the present disclosure.

As illustrated inFIG.6, the liquid crystal display device400includes a liquid crystal panel402as a display panel, a backlight unit420under the liquid crystal panel402. The display device400may further include a main frame430, a top frame440and a bottom frame450for modularizing the liquid crystal panel402and the backlight unit420. The liquid crystal panel402includes first and second substrates410and470and a liquid crystal layer360(ofFIG.5) therebetween. Since the liquid crystal panel402may have similar structure as those inFIG.5, the explanation is omitted. First and second polarization plates412and414transmitting a predetermined light are attached on an outer surface of the first and second substrates410and470, respectively. A linearly-polarized light being parallel to a direction of a transmissive axis of the first and second polarization plates412and414passes through the first and second polarization plates412and414. For example, the transmissive axis of the first and second polarization plates412and414may be perpendicular to each other.

Although not shown, a printed circuit board (PCB) may be connected to at least one side of the liquid crystal panel402via a connection member, for example, a flexible PCB or a tape carrier package. The PCB is bent along a side surface of the main frame430or a rear surface of the bottom frame450during a modularization process of the display device400.

The backlight unit420providing the light is disposed under the liquid crystal panel402in order to display externally the transmittance differences by the liquid crystal panel402. The backlight unit420includes a light emitting diode (LED) assembly500, a reflective plate425of white or silver, a light guide plate423on the reflective plate425and an optical sheet421on the light guide plate423.

In one exemplary aspect, the LED assembly500is disposed at a side of the light guide plate223and includes a plurality of LED packages510and an LED PCB560. The LED packages510are arranged on the PCB560. Each LED package510may comprise an LED chip512(seeFIG.7) emitting red, green and blue lights or white light such that white light is provided from the LED package510toward the light guide plate423. Alternatively, adjacent three LED packages510respectively emit red, green and blue lights, and the lights are mixed to provide the white light.

The LED PCB560is an electronic circuit board that prints a wring pattern (not shown) on an insulating layer made of resin or ceramic to mount electronic devices and enables electrical connection with the LED package510. As an example, the LED PCB560may be, but is not limited to, a FR-4printed circuit board made a reinforced-glass epoxy laminated sheet, a flexible printed circuit board (FPCB) or metal core printed circuit board (MCPCB).

The light from the LED package510of the LED assembly500is incident into the light guide plate423. The light travels the light guide plate423, and a plane light source is provided onto the liquid crystal panel402by a total reflection in the light guide plate423. Patterns for providing uniform plane light may be formed on a rear surface of the light guide plate423. For example, the patterns of the light guide plate423may be an elliptical pattern, a polygonal pattern or a hologram pattern, and those patterns may be formed through a printing process or an injection molding.

The reflective plate425is disposed under the light guide plate423, and the light from the rear side of the light guide plate423is reflected by the reflective plate425to improve the brightness. The optical sheet421on or over the light guide plate423may include a light diffusion sheet or at least one light concentration sheet so that the light passed though the light guide plate423diffuses or focuses to provide uniform plane light to the liquid crystal panel402. The LED packages510may be arranged in a plurality of lines on the LED PCB560.

The liquid crystal panel402and the backlight unit420are modularized by the main frame430, the top frame440and the bottom frame450. The top frame440covers edges of a front surface of the liquid crystal panel402and side surfaces of the liquid crystal panel402. The top frame440has an opening such that images from the liquid crystal panel402can be displayed through the opening of the top frame440. The bottom frame450includes a bottom surface and four side surfaces to cover a rear surface of the backlight unit420and side surfaces of the backlight unit420. The bottom frame450covers a rear side of the backlight unit420. The main frame430has a rectangular frame shape. The main frame430covers side surfaces of the liquid crystal panel402and the backlight unit420and is combined with the top frame440and the bottom frame450.

FIG.7is a cross-sectional view schematically illustrating an LED package in accordance with an exemplary aspect of the present disclosure where inorganic luminescent particles and the dispersants are applied to an encapsulation part. As illustrated inFIG.7, the LED package510includes an LED chip512, and an encapsulation part520covering the LED chip512. The encapsulation part520includes the polyurethane-based dispersant150adsorbed to the surface of the inorganic luminescent particle100that may be a quantum dot and/or a quantum rod as the luminous material.

In one exemplary aspect, the LED package510may be a white LED package which can realize white luminescence. One method of realizing white light includes using an LED chip512enabling ultraviolet (UV) luminescence as a light source, and injecting the polyurethane-based dispersant150adsorbed to the surface of the inorganic luminescent particle100that can emit red (R), green (G) and blue (B) lights in the encapsulation part520. Another method of realizing white light is using an LED chip512, for example, emitting blue light, and injecting the polyurethane-based dispersant150adsorbed to the surface of the inorganic luminescent particle100that can emit red (R), yellow (Y) and/or green (G) lights that can absorb the blue light emitted from the LED chip512in the encapsulation part520.

For example, the LED chip512may be a blue LED chip emitting light of a wavelength range of approximately 430 to 470 nm, and the inorganic luminescent particle100may be a quantum dot or a quantum rod emitting light of a green wavelength range and/or a red wavelength range. In one exemplary aspect, the LED chip512emitting blue light may use sapphire as a substrate, and a material having a blue peak wavelength may be applied as a light source for excitation. As an example, a material for the blue LED chip510may be selected from, but is not limited to, the group consisting of GaN, InGaN, InGaN/GaN, BaMgAl10O7:Eu2+, CaMgSi2O6:Eu2+and a combination thereof.

In this case, the inorganic luminescent particle100may have predetermined photoluminescence wavelengths absorbing strongly the blue light emitted from the blue LED chip510. The inorganic luminescent particle100may be applied on, for example, the LED chip512emitting blue light, thereby overall realizing a white LED.

In addition, the LED package510may further include a case530, and first and second electrode leads542and544connected to the LED chip512via first and second wires552and554and exposed to the outside of the case530. The case530includes a body532and a side wall534protruding from the top surface of the body532to serve as a reflecting surface, and the LED chip512is disposed above the body532, and surrounded by the side wall534.

As described above, the polyurethane-based dispersant150adsorbed to the surface of the inorganic luminescent particle100introduces the pillar structure154(142) having the predetermined length and chemical conformations, thus the inorganic luminescent particle100can improve its dispersion properties and have excellent thermal resistance and luminous efficiency. As the inorganic luminescent particle100adsorbed by the dispersant150can maintain its excellent physical properties even when the heat emitted from the high temperature LED chip512is transferred to the encapsulation part520, it can maintain the intended luminous properties. Accordingly, a luminance of the LED package510including the inorganic luminescent particle100and the dispersant150may increase, and the luminance of an LCD device400including the LED package510is greatly enhanced.

[Inorganic LED and Light Emitting Device]

As described above, the polyurethane-based dispersant150having the pillar structure can be adsorbed stably to the surface of the inorganic luminescent particle100, thus the inorganic luminescent particle100can have excellent thermal property, dispersion property and luminous efficiency. Accordingly, the inorganic luminescent particle100of which the dispersant150is adsorbed on the surface can be introduced into an emissive layer of an inorganic light emitting diode and can be utilized in an inorganic light emitting device.FIG.8is a cross-sectional view schematically illustrating inorganic light emitting display device in accordance with another exemplary aspect of the present disclosure where inorganic luminescent particles and dispersants are applied into an emissive layer. All component of the inorganic light emitting display device in accordance with all aspects of the present invention are operatively coupled and configured.

As illustrated inFIG.8, an inorganic light emitting display device600includes a substrate610, a thin film transistor Tr over the substrate6610and an inorganic light emitting diode D connected to the thin film transistor Tr.

The substrate610may include, but is not limited to, glass, thin flexible material and/or polymer plastics. For example, the flexible material may be selected from the group, but is not limited to, polyimide (PI), polyethersulfone (PES), polyethylenenaphthalate (PEN), polyethylene terephthalate (PET), polycarbonate (PC) and combination thereof. The substrate610, over which the thin film transistor Tr and the LED D are arranged, form an array substrate.

A buffer layer622may be disposed over the substrate610, and the thin film transistor Tr is disposed over the buffer layer622. The buffer layer622may be omitted.

A semiconductor layer620is disposed over the buffer layer622. In one exemplary aspect, the semiconductor layer620may include, but is not limited to, oxide semiconductor materials. In this case, a light-shied pattern may be disposed under the semiconductor layer620, and the light-shield pattern can prevent light from being incident toward the semiconductor layer620, and thereby preventing the semiconductor layer120from being deteriorated by the light. Alternatively, the semiconductor layer620may include polycrystalline silicon. In this case, opposite edges of the semiconductor layer620may be doped with impurities.

A gate insulating layer624made of an insulating material is disposed on the semiconductor layer620. The gate insulating layer624may include, but is not limited to, an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx).

A gate electrode630made of a conductive material such as a metal is disposed over the gate insulating layer624so as to correspond to a center of the semiconductor layer620. While the gate insulating layer624is disposed over a whole area of the substrate610inFIG.8, the gate insulating layer624may be patterned identically as the gate electrode630.

An interlayer insulating layer632made of an insulating material is disposed on the gate electrode630with covering over an entire surface of the substrate610. The interlayer insulating layer632may include, but is not limited to, an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNO, or an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating layer632has first and second semiconductor layer contact holes634and636that expose both sides of the semiconductor layer620. The first and second semiconductor layer contact holes634and636are disposed over both sides of the gate electrode630with spacing apart from the gate electrode630. The first and second semiconductor layer contact holes634and636are formed within the gate insulating layer624inFIG.8. Alternatively, the first and second semiconductor layer contact holes634and636are formed only within the interlayer insulating layer632when the gate insulating layer624is patterned identically as the gate electrode630.

A source electrode644and a drain electrode466, each of which includes a conductive material such as a metal, are disposed on the interlayer insulating layer632. The source electrode644and the drain electrode646are spaced apart from each other with respect to the gate electrode630, and contact both sides of the semiconductor layer620through the first and second semiconductor layer contact holes634and636, respectively.

The semiconductor layer620, the gate electrode630, the source electrode644and the drain electrode646constitute the thin film transistor Tr, which acts as a driving element. The thin film transistor Tr inFIG.8has a coplanar structure in which the gate electrode630, the source electrode644and the drain electrode646are disposed over the semiconductor layer620. Alternatively, the thin film transistor Tr may have an inverted staggered structure (see,FIG.5) in which a gate electrode is disposed under a semiconductor layer and source and drain electrodes are disposed over the semiconductor layer. In this case, the semiconductor layer may include, but are not limited to, amorphous silicon.

Although not shown inFIG.8, a gate line and a data line, which cross each other to define a pixel region, and a switching element, which is connected to the gate line and the data line, may be further formed in the pixel region. The switching element is connected to the thin film transistor Tr, which is a driving element. In addition, a power line is spaced apart in parallel from the gate line or the data line, and the thin film transistor Tr may further includes a storage capacitor configured to constantly keep a voltage of the gate electrode for one frame.

Moreover, the inorganic light emitting display device600may include a color filter that comprises dyes or pigments for transmitting specific wavelength light of light emitted from the LED D. For example, the color filter can transmit light of specific wavelength such as red (R), green (G), blue (B) and/or white (W). Each of red, green, and blue color filter may be formed separately in each pixel region. In this case, the inorganic light emitting display device800can implement full-color through the color filter.

A passivation layer650is disposed on the source and drain electrodes644and646over the whole substrate610. The passivation layer650has a flat top surface and a drain contact hole652that exposes the drain electrode646of the thin film transistor Tr. While the drain contact hole652is disposed on the second semiconductor layer contact hole636, it may be spaced apart from the second semiconductor layer contact hole636.

The inorganic LED D includes a first electrode710that is disposed on the passivation layer650and connected to the drain electrode646of the thin film transistor Tr. The inorganic LED D further includes an emissive layer720and a second electrode730each of which is disposed sequentially on the first electrode710.

The first electrode710is disposed in each pixel region. The first electrode710may be an anode and include a conductive material having relatively high work function value. For example, the first electrode710may include, but is not limited to, a doped or undoped metal oxide such as indium-tin-oxide (ITO), indium-zinc-oxide (IZO), indium-tin-zinc oxide (ITZO), indium-copper-oxide (ICO), tin oxide (SnO2), indium oxide (In2O3), cadmium:zinc oxide (Cd:ZnO), fluorine:tin oxide (F:SnO2), indium:tin oxide (In:SnO2), gallium:tin oxide (Ga:SnO2) or aluminum:zinc oxide (Al:ZnO; AZO). Optionally, the first electrode210may include a metal or nonmetal material such as nickel (Ni), platinum (Pt), gold (Au), silver (Ag), iridium (Ir) or a carbon nanotube (CNT), other than the above-described metal oxide.

In one exemplary aspect, when the inorganic light emitting display device700is a top-emission type, a reflective electrode or a reflective layer (not shown) may be disposed under the first electrode710. For example, the reflective electrode or the reflective layer (not shown) may comprise, but are not limited to, aluminum-palladium-copper (APC) alloy. In addition, a bank layer660is disposed on the passivation layer650in order to cover edges of the first electrode710. The bank layer660exposes a center of the first electrode710.

An emissive layer720is disposed on the first electrode710. In one exemplary aspect, the emissive layer720may have a mono-layered structure of an emitting material layer (EML). Alternatively, the emissive layer720may further include plural charge transfer layers as well as the EML. For example, the emissive layer720includes an EML740(see,FIG.9), a first charge transfer layer (CTL1)750(see,FIG.9) and a second charge transfer layer (CTL2)770(see,FIG.9), and optionally an exciton charge layer. The emissive layer720may have one emitting unit or have multiple emitting units to form a tandem structure.

The second electrode730is disposed over the substrate612above which the emissive layer720is disposed. The second electrode730may be disposed over a whole display area, may include a conductive material having a relatively low work function value compared to the first electrode710, and may be a cathode. For example, the second electrode730may include, but is not limited to, Ca, Ba, Ca/Al, LiF/Ca, LiF/Al, BaF2/Al, CsF/Al, CaCO3/Al, BaF2/Ca/Al, Al, Mg, Au:Mg or Ag:Mg.

In addition, an encapsulation film670may be disposed over the second electrode730in order to prevent outer moisture from penetrating into the LED D. The encapsulation film670may have, but are not limited to, a laminated structure of a first inorganic insulating film672, an organic insulating film674and a second inorganic insulating film676.

Moreover, a polarizer may be attached to the encapsulation film670in order to decrease external light reflection. For example, the polarizer may be a circular polarizer. In addition, a cover window may be attached to the encapsulation film670or the polarizer. In this case, the substrate610and the cover window may have a flexible property, thus the inorganic light emitting display device600may be a flexible display device.

The emissive layer720includes the dispersant150adsorbed to the surface of the inorganic luminescent particle100(see,FIG.9). The inorganic luminescent particle100has excellent dispersion property and can maintain its thermal resistance and luminous efficiency even exposing the external oxygen, moisture and/or high temperature during the fabricating the inorganic LED D.

Now, we will describe the inorganic LED having the inorganic luminescent particle and the dispersant in more detail.FIG.9is a cross-sectional view schematically illustrating an inorganic light emitting diode in accordance with an exemplary aspect of the present disclosure where inorganic luminescent particles and the dispersant are applied into an emissive layer. As illustrated inFIG.9, the inorganic LED D includes a first electron710, a second electrode730and an emissive layer720disposed between the first electrode710and the second electrode730. The emissive layer730comprises an EML740. Also, the emissive layer720comprises a CTL1750disposed between the first electrode710and the EML740and a CTL2770disposed between the EML740and the second electrode730. Alternatively, the emissive layer720may further comprise a first exciton blocking layer, an electron blocking layer (EBL, not shown) disposed between the EML740and the CTL1750and/or a second exciton blocking layer, a hole blocking layer (HBL, not shown) disposed between the EML740and the CTL2770.

The first electrode710may be an anode such as a hole injection electrode. The first electrode710may be formed on a substrate610(see,FIG.8) formed of glass or a polymer. As an example, the first electrode710may be a doped or undoped metal oxide such as ITO, IZO, ITZO, ICO, Snot, In2O3, Cd:ZnO, F:SnO2, In:SnO2, Ga:SnO2) or AZO. Optionally, the first electrode710may consist of a metal or nonmetal material containing Ni, Pt, Au, Ag, Ir or a CNT, other than the above-described metal oxide.

The second electrode730may be a cathode such as an electron injection electrode. As an example, the second electrode730may consist of Ca, Ba, Ca/Al, LiF/Ca, LiF/Al, BaF2/Al, CsF/Al, CaCO3/Al, BaF2/Ca/Al, Al, Mg, Au:Mg or Ag:Mg. As an example, each of the first electrode710and the second electrode730may be stacked to a thickness of 30 to 300 nm.

In one exemplary aspect, in the case of a bottom emission-type inorganic LED, the first electrode710may consist of a transparent conductive metal oxide such as ITO, IZO, ITZO or AZO, and as the second electrode730, Ca, Ba, Ca/Al, LiF/Ca, LiF/Al, BaF2/Al, Al, Mg, or an Ag:Mg alloy may be used.

The EML740comprises the dispersant150adsorbed to the surface of the inorganic luminescent particle100that may be the quantum dot or the quantum rod. The pillar structure154(see,FIG.2) introduced into the dispersant150with predetermined length and chemical conformation enables the inorganic luminescent particle100to be dispersed in the polar solvent as well as the non-polar solvent. The inorganic luminescent particles100can minimize their agglomerations and FRET to adjacent distributed particles due to the sterical hindrance caused by the pillar structure154. As the dispersant150is adsorbed stably to the inorganic luminescent particle100, the particle100can maintain its luminous efficiency even exposing to the external oxygen, moisture and high temperature.

When the EML740comprises the inorganic luminescent particles100such as the quantum dots and the quantum rods and the dispersant adsorbed to the surface of the inorganic luminescent particle100, the EML740may be formed using a solution in which the inorganic luminescent particles100adsorbed by the dispersant150is dispersed in a solvent. The EML740may be formed by applying the solution in which the inorganic luminescent particles100are dispersed by the dispersant150onto the CTL1750, and then by evaporating the solution. In one exemplary aspect, the EML740including the inorganic luminescent particles100and the dispersant150may be laminated on the CTL1750using any solution process such as spin coating, drop coating, dip coating, spray coating, roll coating, flow coating casting, screen printing and inkjet printing, or a combination thereof.

The CTL1750may be a hole transfer layer which provides holes with the EML740. As an example, the CTL1750may include a hole injection layer (HIL)752disposed adjacently to the first electrode710between the first electrode710and the EML740, and a hole transport layer (HTL)754disposed adjacently to the EML740between the first electrode710and the EML740.

The HIL752facilitates the injection of holes from the first electrode710into the EML740. As an example, the HIL752may include, but is not limited to, an organic material selected from the group consisting of poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS); 4,4′,4″-tris(diphenylamino)triphenylamines (TDATA) doped with tetrafluoro-tetracyano-quinodimethane (F4-TCNQ); p-doped phthalocyanine such as zinc phthalocyanine (ZnPc) doped with F4-TCNQ; N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4″-diamine (α-NPD) doped with F4-TCNQ; hexaazatriphenylene-hexanitrile (HAT-CN); and a combination thereof. As an example, the HIL752may include the dopant such as F4-TCNQ between about 1 wt % to about 30 wt %. The HIL752may be omitted in compliance with a structure of the LED D.

The HTL754transports holes from the first electrode710into the EML740. The HTL754may include an inorganic material or an organic material. As an example, when the HTL754includes an organic material, the HTL754may include, but is not limited to, 4,4′-bis(p-carbazolyI)-1,1′-biphenyl compounds such as CBP and CDBP; aromatic amines, i.e. aryl amines or polynuclear aromatic amines selected from the group consisting of α-NPD, N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TPD), N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-spiro (spiro-TPD), N,N′-di(4-(N,N′-diphenyl-amino)pheyl)-N,N′-diphenylbenzidine (DNTPD), tris(4-carbazolyl-9-ylphenyl)amine (TCTA), tetra-N-phenylbenzidine (TPB), tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), poly(9,9′-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine (TFB), poly(4-butylphenyl-dipnehyl amine) (poly-TPD) and combination thereof; conductive polymers such as polyaniline, polypyrrole, PEDOT:PSS; PVK and its derivatives; poly(para)phenylene vinylenes (PPV) and its derivatives such as poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MOMO-PPV); polymethacrylate and its derivatives; poly(9,9-octylfluorene) and its derivatives; poly(spiro-fluorene) and its derivatives; metal complexes such as copper phthalocyanine (CuPc); and combination thereof.

Alternatively, when the HTL754includes an inorganic material, the HTL754may comprise an inorganic material selected from the group consisting of a metal oxide nanocrystal, a non-oxide metal nanocrystal and combination thereof. The metal oxide nanocrystal that can be used in the HTL754may be selected from, but is not limited to, the group consisting of ZnO, TiO2, CoO, CuO, Cu2O, FeO, In2O3, MnO, NiO, PbO, SnOx, Cr2O3,v2O5, Ce2O3, MoO3, Bi2O3, ReO3and combination thereof. The non-oxide metal nanocrystal may comprise, but is not limited to, CuSCN, Mo2S and p-type GAN. Alternatively, the metal oxide and/or the non-oxide metal nanocrystal in the HTL754may be doped with a p-dopant. As an example, the p-dopant may be selected from, but is not limited to, Li+, Na+, K+, Sr+, Ni2+, Mn2+, Pb2+, Cu+, Cu2+, Co2+, Al3+, Eu3+, In3+, Ce3+, Er3+, Tb3+, Nd3+, Y3+, Cd2+, Sm3+, N, P, As and combination thereof.

InFIG.8, while the CTL1750is divided into the HIL752and the HTL754, the CTL1750may have a mono-layered structure. For example, the CTL1750may include only the HTL754without the HIL752or may include the above-mentioned hole transporting material doped with the hole injection material (e.g. PEDOT:PSS).

The CTL1750including the HIL752and the HTL754may be formed by any vacuum deposition process such as vacuum vapor deposition and sputtering, or by any solution process such as spin coating, drop coating, dip coating, spray coating, roll coating, flow coating, casting, screen printing and inkjet printing, or a combination thereof. For example, each of the HIL752and the HTL754may have a thickness, but is not limited to, between about 10 nm and 200 nm, alternatively, about 10 nm and 100 nm.

The CTL2770is disposed between the EML740and the second electrode730. The CTL2770may be an electron transfer layer which provides electrons into the EML740. In one exemplary aspect, the CTL2770may include an electron injection layer (EIL)772disposed adjacently to the second electrode730between the second electrode730and the EML740, and an electron transport layer (ETL)774disposed adjacently to the EML740between the second electrode730and the EML740.

The EIL772facilitates the injection of electrons from the second electrode730into the EML740. For example, the EIL772may include, but is not limited to, a metal such as Al, Cd, Cs, Cu, Ga, Ge, In and/or Li, each of which is undoped or doped with fluorine; and/or metal oxide such as TiO2, ZnO, ZrO2, SnO2, WO3and/or Ta2O3, each of which is undoped or doped with Al, Mg, In, Li, Ga, Cd, Cs or Cu.

The ETL774transfers electrons into the EML740and comprises an inorganic material or an organic material. In one exemplary aspect, when the EML740includes the inorganic luminescent particle100, the ETL774may include an inorganic material so as to prevent an interface defect from being formed at an interface between the EML740and the ETL774, and thereby securing driving stability of the LED D. In addition, when the ETL774includes an inorganic material having high charge mobility, the electron transport rate provided from the second electrode730may be improved, and electrons can be transported efficiently into the EML740owing to high electron levels or concentrations.

Moreover, when the EML740includes an inorganic luminescence particle100, the inorganic luminescence particle100typically has a very deep VB (valence band) energy level. An organic compound having electron transporting property usually has a HOMO energy level shallower than the VB energy level of the inorganic luminescent particle100. In this case, the holes injected from the first electrode710into the EML740including the inorganic luminescent particle100may be leaked to the second electrode730via the ETL774including the organic compound.

In one exemplary aspect, the ETL774may include an inorganic material having relatively deep VB energy level compared to VB energy level of the inorganic luminescence particle100in the EML740. As an example, an inorganic material having wide energy level bandgap (Eg) between the VB energy level and a conduction band (CB) energy level may be used as an electron transporting material of the ETL774. In this case, hole injected into the EML740including the inorganic luminescent particle100is not leaked to the ETL774and electrons can be efficiently injected into the EML740from the second electrode730via the ETL774.

In one exemplary aspect, the ETL774may comprise, but is not limited, an inorganic material such as a metal oxide nanocrystal, a semiconductor nanocrystal, a nitride and/or combination thereof. For Example, the ETL774may comprise the metal oxide nanocrystal.

As an example, the metal oxide nanocrystal in the ETL774may comprise, but is not limited to, an oxide nano particle of a metal component selected from the group consisting of Zn, Ca, Mg, Ti, Sn, W, Ta, Hf, Al, Zr, Ba and combination thereof. More particularly, the metal oxide in the ETL774may comprise, but is not limited to, TiO2, ZnO, ZnMgO, ZnCaO, ZrO2, SnO2, SnMgO, WO3, Ta2O3, HfO3, Al2O3, BaTiO3, BaZrO3and combination thereof. The semiconductor nanocrystal in the ETL774may comprise, but is not limited to CdS, ZnSe, ZnS, and the like, the nitride in the ETL774may comprise, but is not limited to, Si3N4.

In one exemplary aspect, the ETL774may be designed to have the CB energy level substantially equal to the CB energy level of the EML740while the VB energy level deeper than the VB energy level of the EML740. The ETL774may further comprise n-doped component (n-dopant) to the inorganic nano particles. The n-dopant in the ETL774may comprise, but is not limited to, metal cation selected from Al, Mg, In, Li, Ga, Cd, Cs, Cu, preferably trivalent cation.

Similar to the CTL1750, whileFIG.9illustrates the CTL2770as a bi-layered structure including the EIL772and the ETL774, the CTL2770may have a mono-layered structure having only the ETL774. Alternatively, the CTL2770may have a mono-layered structure of ETL774including a blend of the above-described electron-transporting inorganic material with cesium carbonate.

The CTL2770, which includes the EIL772and/or the ETL774, may be formed on the EML740by any vacuum deposition process such as vacuum vapor deposition and sputtering, or solution process such as spin coating, drop coating, dip coating, spray coating, roll coating, flow coating, casting, screen printing and inkjet printing, or combination thereof. As an example, each of the EIL772and the ETL774may have a thickness, but is not limited to, between about 10 nm and about 200 nm, alternatively, about 10 nm and 100 nm.

For example, the inorganic LED D may have a hybrid CTL structure in which the HTL754of the CTL1750includes the organic material as describe above and the CTL2770, for example, the ETL774includes the inorganic material as described above. In this case, The LED D may enhance its luminous properties.

In an alternative aspect, when holes are transferred to the second electrode730via the EML740and/or electrons are transferred to the first electrode710via the EML740, the inorganic LED D may have short lifetime and reduced luminous efficiency. In order to prevent these phenomena, the inorganic LED D may have at least one exciton blocking layer adjacent to the EML740.

Also, the inorganic LED D may further include the HBL (not shown) as a second exciton blocking layer between the EML740and the ETL774so that holes cannot be transferred from the EML740to the ETL774. In one exemplary aspect, the HBL (not shown) may comprise, but is not limited to, oxadiazole-based compounds, triazole-based compounds, phenanthroline-based compounds, benzoxazole-based compounds, benzothiazole-based compounds, benzimidazole-based compounds, and triazine-based compounds and aluminum-based complexes. For example, the HBL (not shown) may comprise a compound having a relatively low HOMO energy level compared to the luminescent materials in EML740. The HBL (not shown) may comprise, but is not limited to, BCP, BAlq, Alq3, PBD, spiro-PBD, Liq.

The polyurethane-based dispersant150introducing stable pillar structure154(see,FIG.2) can be adsorbed to the surface of the inorganic luminescent particle100so that the particle100can improve its dispersion properties, thermal resistance and luminous efficiency, thus the composition including the dispersant150adsorbed to inorganic luminescent particle100can be applied into a color conversion layer in the light emitting device.FIG.10is a cross-sectional view schematically illustrating a light emitting display device in accordance with an exemplary aspect of the present disclosure where a color conversion layer including inorganic luminescent particles and the dispersants are applied and has a white LED (W-LED).

As illustrated inFIG.10, the light emitting device800includes a first substrate810a second substrate870facing oppositely to the first substrate810, a light emitting diode (LED) D disposed between the first and second substrates810and870, a color filter layer820disposed between the LED D and the second substrate870, and a color conversion layer830disposed between the color filter layer820the LED D. A red pixel region Rp, a green pixel region Gp, a blue pixel region Bp and a white pixel region Wp are defined in the first substrate810, the color filter layer820includes color filter patterns822,824and826each of which corresponds to each of the red, green and blue pixel regions Rp, Gp and Bp, respectively, and the color conversion layer830corresponds to each of the red and green pixel regions Rp and Gp.

The first substrate810may be made of transparent material. For example, the first substrate810may be a glass substrate, a thin flexible substrate and a polymeric plastic substrate. The second substrate870may be made of transparent or obscured materials. For example, the second substrate870may be made of glass, plastics such as polyimide and a metal foil.

A polarizing plate (not shown) may be attached onto a display plane of the light emitting display device800, for example to an external surface of the first substrate810in order to prevent the external light from reflecting to the LED D. The polarizing plate (not shown) may be a right-handed circular polarizing plate or a left-handed circular polarizing plate.

An adhesive layer850is disposed between the second substrate870and the LED D, for example between the color filter layer820or the color conversion layer830and the LED D, and an encapsulation film (not shown) may be disposed on the LED D and the adhesive layer850in order to prevent the external moisture from being infiltrated into the LED D. While not shown inFIG.10, a gate line and a data line which cross each other and defines the red, green, blue and white pixel regions Rp, Gp, Bp and Wp, and a power line that extends parallel to the gate line or the data line are formed on the first substrate810.

Also, thin film transistor Tr as the driving element is disposed in each pixel region Rp, Gp, Bp or Wp. The LED D is electrically connected to the thin film transistor Tr of the driving element. The thin film transistor Tr may comprise a semiconductor layer, a gate electrode on the semiconductor layer and source and drain electrodes spaced apart over the gate electrode and connected to the semiconductor layer (see,FIG.8).

In addition, a switching element connected electrically to the thin film transistor, the gate line and the data line and a storage capacitor connected to the switching element and the power line may be formed in each pixel region Rp, Gp, Bp or Wp on the first substrate810. As the switching element is turned on by a gate signal applied to the gate line, the data signal applied to the data line is applied to the gate electrode of the thin film transistor as the driving element and an electrode of the storage capacitor through the switching element.

The thin film transistor is turned on by the data signal applied to the gate electrode, and the resulting current proportional to the data signal flows from the power line to the LED D through the thin film transistor as the driving element, and the LED D emit light with luminance proportional to the current though the thin film transistor Tr.

A passivation layer is formed on the thin film transistor Tr. The passivation layer may be formed of inorganic insulating material such as silicon oxide and silicon nitride, or organic insulating material such as photo acryl.

The color filter layer820may be disposed on or over the second substrate870and includes a red color filter pattern822, a green color filter pattern824and a blue color filter pattern826each of which corresponds to the red, green and blue pixel regions Rp, Gp and Bp, respectively. The white (W) light emitted from the LED D in each of the red, green and blue pixel regions Rp, Gp and Bp passes through each of the red, green and blue color filter patterns822,824and826, respectively, and then each of red, green and blue lights is passed though the second substrate870in the respective pixel regions Rp, Gp and Bp, while white light is passed through the second substrate870in the white pixel region Wp.

The red color filter pattern822(R-CF) comprises a red pigment or a red dye that absorbs the light of blue to green wavelength ranges among the white light and transmits the light of red wavelength ranges. The green color filter pattern824(G-CF) comprises a green pigment or a green dye that absorbs the light of blue wavelength ranges and red wavelength ranges among the white light and transmits the light of green wavelength ranges. The blue color filter pattern826(B-CF) comprises a blue pigment or a blue dye that absorbs the light of green to red wavelength ranges among the white light and transmits the light of blue wavelength ranges.

When only the color filter layer820is disposed between the second substrate870and the LED D, only the light of specific wavelength ranges among the white light emitted from the LED D can transmit to the second substrate870in each of the red, green and blue pixel regions Rp, Gp and Bp. In other words, only the light of red wavelength ranges can pass through the red pixel region Rp, only the light of green wavelength ranges can pass through the green pixel region Gp and only the light of blue wavelength ranges can pass through the blue pixel region Bp, thus the out-coupling efficiency of the LED D may be deteriorated.

The color conversion layer830including the dispersant150adsorbed on the surface of the inorganic luminescent particles100aand100bis formed on the color filter layer820. More particularly, the color conversion layer830includes a red color conversion layer832positioned on the red color filter pattern822corresponding to the red pixel region Rp, and a green color conversion layer834positioned on the green color filter pattern824corresponding to the green pixel region Gp. When the white light is emitted from the LED D, the color conversion layer830is formed in the red pixel region Rp and the green pixel region Gp, but is not formed in the blue pixel region Bp and the white pixel region Wp.

The red color conversion layer832includes the dispersant150adsorbed on the surface of the red inorganic luminescent particle100a. The red inorganic luminescent particle100amay be a red quantum dot or a red quantum rod. The red color conversion layer832converts the light emitting from the LED D into a red wavelength range, for example, a light having peak wavelength ranges between about 600 nm and about 640 nm.

The green color conversion layer834includes the dispersant150adsorbed on the surface of the green inorganic luminescent particle100b. The red inorganic luminescent particle100bmay be a green quantum dot or a green quantum rod. The green color conversion layer834converts the light emitting from the LED D into a green wavelength range, for example, a light having peak wavelength ranges between about 500 nm and about 570 nm.

As the white (W) light emitted from the LED D passes through the red color conversion layer832positioned correspondingly to the red pixel region Rp, the blue (B) and green (G) light, which has shorter wavelength compared to the red (R) light, among the white light are converted to the red (R) light. Accordingly, as most of the white (W) light emitted from the LED D in the red pixel region Rp passes through the red color filter pattern822in a state converted to red wavelength light, the light amount absorbed in the red color filter pattern822is reduced, and thereby improving out-coupling efficiency.

In addition, as the white (W) light emitted from the LED D passes through the green color conversion layer834positioned correspondingly to the green pixel region Gp, the blue (B) light, which has shorter wavelength compared to the green (G) light, among the white light are converted to the green (G) light. Accordingly, as most of the white (W) light emitted from the LED D in the green pixel region Gp passes through the green color filter pattern824in a state converted to green wavelength light, the light amount absorbed in the green color filter pattern824is reduced, and thereby improving out-coupling efficiency.

As described above, the color conversion layer830is not formed in the blue pixel region Bp. In general, when converting the light wavelength, it is difficult to convert relatively low energy light (long wavelength light) to relatively high energy light (short wavelength light). Since high energy light is emitted in the blue pixel region Bp, it is not easy to convert the white (W) light to blue (B) light through the color conversion layer830. For this reason, the color conversion layer830is not positioned in the blue pixel region Bp. As the white (W) light emitted from the OLED D in the blue pixel region Bp passes through the blue color filter pattern826, the blue color filter pattern826passes through only the blue light with absorbing light in wavelength ranges other than blue wavelength ranges.

In addition, both the color filter pattern820and the color conversion layer8320are not positioned in the white pixel region Wp, thus the while (W) light emitted from the LED D transmits as it is. In an alternative aspect, the color filter layer820may be omitted in case of positioning the color conversion layer830.

In accordance with one aspect, the color conversion film830including the red and green color conversion layers832and834each of which converts the light emitted from the LED to light of specific wavelength ranges are positioned in the red and green pixel regions Rp and Gp. While the white (W) light emitted from the LED D passes through the color conversion layers832and834in the specific pixel regions, the white light is converted to a light of specific wavelength ranges capable of transmitting the respective color filter patterns822and824. Accordingly, the light amount absorbed by the red green color filter patterns822and824can be minimized to improve out-coupling efficiency.

When the color conversion layer includes only the inorganic luminescent particles100aand100b, the dispersion density of the particles100aand100bdispersed in the binder is much limited. In this case, light leakage of the white light is caused in the color conversion layer containing only the inorganic luminescent particles100aand100b, and the luminance of the LED D is lowered as the color filter layer820blocks the light leakage. On the other hand, each of the color conversion layers832and834includes a dispersant150stably adsorbed on the surface of the inorganic luminescent particles100aand100, thus the luminous efficiency of the particles100aand100bis not deteriorated. As the light conversion efficiency in the color conversion layer830is improved, light leakage in the color conversion layer830is minimized, thus luminance of light emitted from the LED D is not lowered.

In the above aspect, the color conversion layer830is divided into the red color conversion layer832that is positioned in the red pixel region Rp and comprises the red inorganic luminescent particle100a, and the green color conversion layer834that is positioned in the green pixel region Gp and comprises the green inorganic luminescent particle100b. Alternatively, the color conversion layer830may be positioned over the whole red and green pixel regions Rp and Gp, and may comprise a single color conversion layer comprising the dispersant150adsorbed on a surface of red-green inorganic luminescent particles. Also, the color conversion layer may be positioned in the whole red, green and blue pixel regions Rp, Gp and Bp except the white pixel region Wp. In this case, a single color conversion layer may comprise the dispersant150adsorbed on the surface of the red inorganic luminescent particle100a. Further, the light emitted from the LED D is not limited to the white (W) light, but may be blue (B) light.

The LED D comprises a first electrode842, an emissive layer844on the first electrode842and a second electrode on the emissive layer844. The configuration of the LED may be identical to the LED D illustrated inFIG.9. The emissive layer844is disposed on the first electrode842and may various light colors including white and blue, and the like. InFIG.10, the LED D illustrates a single layered emissive layer844between the first and second electrodes842and846. Alternatively, the emissive layer844in the LED D may comprise an EML, at least one CTL and/or at least one exciton blocking layer, and may have a tandem structure with multiple emitting units. Also, while the emissive layer844is formed in the whole display area including the red, green, blue and white pixel regions Rp, Gp, Bp and Wp inFIG.10, the emissive layer844may be positioned separately in each of the pixel regions Rp, Gp, Bp and Wp.

In one exemplary aspect the LED D may be an inorganic LED in which inorganic luminescent particles such as quantum dots and quantum rods are introduced into the EML. Alternatively, the LED D may be an organic LED (OLED) in which organic luminescent material is introduced into the EML. When the LED D is the OLED, the EML comprise the organic luminescent materials. In this case, the organic luminescent materials are not particularly limited. For example, the EML may comprise organic luminescent materials emitting red, green and/or blue lights, and may include phosphorescent materials as well as fluorescent materials including the delayed fluorescent materials. The organic luminescent materials in the EML may comprise a host and a dopant. When the organic luminescent materials includes the host-dopant, the contents of the dopant in the EML may be, but is not limited to, between about 1 wt % and about 50 wt %, preferably about 1 wt % and about 30 wt %.

The organic host in the EML is not particularly limited and may comprise any host. For example, the organic host in the EML may comprise, but is not limited to, Alq3, TCTA, PVK, 4,4′-bis(N-carbazolyl)-1,1′-biphenyl(CBP), 4,4′-Bis(9-carbazolyl)-2,2′-dimethylbiphenyl (CDBP), 9,10-di(naphthalene-2-yl)anthracene (ADN), 3-tert-butyl-9,10-di(naphtha-2-yl)anthracene (TBADN), 2-methyl-9,10-bis(naphthalene-2-yl)anthracene (MADN), TPB, distyrylarylene (DSA), mCP, 1,3,5-tris(carbazol-9-yl)benzene (TCP), and the like.

When the EML emits red light, the red dopant in the EML may comprise, but is not limited to, an organic compound or an organic metal complex such as 5,6,11,12-tetraphenylnaphthalene (Rubrene), Bis(2-benzo[b]-thiophene-2-yl-pyridine) (acetylacetonate)iridium(III) (Ir(btp)2(acac)), Bis[1-(9,9-diemthyl-9H-fluorn-2-yl)-isoquinoline](acetylacetonate)iridium(III) (Ir(fliq)2(acac)), Bis[2-(9,9-diemthyl-9H-fluorn-2-yl)-quinoline](acetylacetonate)iridium(III) (Ir(flq)2(acac)), Bis-(2-phenylquinoline)(2-(3-methylphenyl) pyridinate)irideium(III) (Ir(phq)2typ), Iridium(III)bis(2-(2,4-difluorophenyl) quinoline)picolinate (FPQIrpic), and the like.

When the EML emits green light, the green dopant in the EML may comprise, but is not limited to, an organic compound or an organic metal complex such as N,N′-dimethyl-quinacridone (DMQA), coumarine, 6,9,10-bis[N,N-di-(p-tolyl)amino]anthracene (TTPA), 9,10-bis[phenyl(m-tolyl)-amino]anthracene (TPA), Bis(2-phenylpyridine)(acetylacetonate)iridium(III) (Ir(ppy)2(acac)), fac-tris(phenylpyridine)iridium(III) (fac-Ir(ppy)3), tris[2-(p-tolyl) pyridine]iridium(III) (Ir(mppy)3), and the like.

When the EML emits blue light, the blue dopant in the EML may comprise, but is not limited to, an organic compound or an organic metal complex such as 4,4′-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), perylene, 2,5,8,11-tetra-tert-butylpherylene (TBPe), Bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carbozylpyridyl)iridium(III) (FirPic), mer-tris(1-phenyl-3-methylimidazolin-2ylidene-C,C2′)iridium(III) (mer-Ir(pmi)3), tris(2-(4,6-difluorophenyl) pyridine)iridium(III) (Ir(Fppy)3), and the like.

When the EML includes the organic luminescent materials, the EML may be formed by any vacuum deposition process such as vacuum vapor deposition and sputtering, or solution process such as spin coating, drop coating, dip coating, spray coating, roll coating, flow coating, casting, screen printing and inkjet printing, or combination thereof. As an example, the EML may have a thickness of, but is not limited to, between about 5 nm and about 300 nm, preferably about 10 nm and about 200 nm.

A bank layer840covering the edge of the first electrode842may be formed beneath the emissive layer844. When current is applied to the LED D, the white (W) light is emitted from the LED D, and then the white light passes through the color conversion layer830and the color filter layer820. In this case, the light emitting display device800may be a top-emission type. In another exemplary aspect, the light emitting display device may be a bottom-emission type. In this case, the color filter layer may be positioned on or over the first substrate810and the color conversion layer may be disposed between the color filter layer and the LED.

InFIG.10, the LED D is described as a quantum LED including an inorganic luminescent particles such as quantum dots or quantum rods or as an OLED including the organic luminescent materials. Alternatively, the LED may be a micro light emitting diode (micro LED).FIG.11is a cross-sectional view schematically illustrating a light emitting display device in accordance with an exemplary aspect of the present disclosure where a color conversion layer including inorganic luminescent particles and dispersants and a blue micro LED as a light emitting diode is applied.FIG.12is a cross-sectional view schematically illustrating of a micro LED in accordance with one exemplary aspect of the present disclosure.

As illustrated inFIG.11, the light emitting display device900comprises a first substrate910, a second substrate970disposed oppositely to the first substrate910, a micro LED980disposed between the first and second substrates910and970, a color filter layer920disposed between the micro LED980and the second substrate970and a color conversion layer930disposed between the micro LED980and the color filter layer920. In the first substrate910, a red pixel region Rp, a green pixel region Gp and a blue pixel region Bp are defined, the color filter layer920are positioned corresponding to the red and green pixel regions Rp and Gp and the color conversion layer930are positioned corresponding to at least the red and green pixel regions Rp and Gp.

The first substrate910may be made of transparent material. For example, the first substrate910may be a glass substrate, a thin flexible substrate and a polymeric plastic substrate. The second substrate970may be made of transparent or obscured materials. For example, the second substrate970may be made of glass, plastics such as polyimide and a metal foil. An encapsulation film is disposed between the second substrate970and the micro LED980for preventing the external moisture from infiltrating into the micro LED980, and an adhesive layer960may be disposed between the encapsulation film960and the second substrate970.

Thin film transistor Tr as the driving element is disposed in each pixel region Rp, Gp or Bp. The thin film transistor Tr may comprise a semiconductor layer, a gate electrode on the semiconductor layer and source and drain electrodes spaced apart over the gate electrode and connected to the semiconductor layer. In this case, the drain electrode (not shown) may act as a first electrode applying the single into the micro LED980.

A second electrode911made of conductive material is disposed on a gate insulating layer (not shown) in respective pixel region Rp, Gp and Bp. A first insulating layer912is formed on the first substrate910over which the thin film transistor Tr, and the micro LED980is disposed on the first insulating layer913. For example, the micro LED980may be disposed within a concave portion913which is formed by removing a portion of the first insulating layer912. The first insulating layer912may be made of inorganic insulating material such as silicon oxide (SiOx) and silicon nitride (SiNx), and/or organic insulating material such as photo acryl.

The micro LED980may comprise, but is not limited to, Group III-V nitride semiconductor materials. For example, as illustrated inFIG.12, the micro LED980may comprise an undoped GaN layer984, n-type GaN layer985on the GaN layer984, an active layer986having a Multi-Quantum-Well (MQW) structure on the n-type GaN layer984, a p-type GaN layer987on the active layer986, an ohmic contact layer988made of transparent conductive material on the p-type GaN layer987, a p-type electrode981contacting a portion of the ohmic contact layer988and an n-type electrode983contacting a portion of the n-type GaN layer985exposed by etching a portion of the active layer946, the p-type GaN layer987and the ohmic contact layer988.

The n-type GaN layer985provides electrons to the active layer986and may be formed by doping n-type impurities such as silicon to the GaN semiconductor layer. The active layer986emits light by recombining injected electrons and holes. While not illustrating in detail, the MQW structure in the active layer986has alternately arranged plural barrier layers and well layers where each of the well layers comprises InGaN layer and each of the barrier layers comprises GaN, but the present disclosure is not limited thereto. The p-type GaN layer987provides holes to the active layer986and may be formed by doping p-type impurities such as Mg, Zn and Mg to the GaN semiconductor layer. The ohmic contact layer988is disposed between the p-type GaN layer987and the p-type electrode981and may be formed of transparent metal oxide such as ITO, IGZO and IZO. Alternatively, each of the p-type electrode981and the n-type electrode983may have a single layer or multiple layers made of metal selected from Ni, Au, Pt, Ti, Al, Cr, alloy thereof or combination thereof.

When the electrical power is applied into the p-type electrode981and the n-type electrode983in the micro LED980, electrons and holes are injected into the active layer946from respective the n-type GaN layer945and the p-type GaN layer987, and then light emits externally as excitons are formed and disappeared in the active layer986. The wavelength of the light emitted from the micro LED980may be controlled by adjusting the thicknesses of the barrier layer in the MQW structure. As an example, the micro LED980may emit blue light, and may have a thickness of between about 10 um and about 100 um.

While not shown in the drawings, the micro LED980may be fabricated by forming a buffer layer on a substrate and growing GaN thin films on the buffer layer. The substrate for growing the GaN thin films may comprise, but is not limited to, sapphire, silicon, GaN, silicon carbide (SiC), gallium arsenide (GaAs) and ZnO. While the micro LED980is positioned on the first insulating layer912inFIG.12, the micro LED is not limited to such specific structured micro LED and various micro LEDs such as a vertical structured micro Led and a horizontal structured micro LED may be applied into the present disclosure.

Referring back toFIG.11, a second insulating layer914is disposes on the first insulating layer912over which the micro LED980is transferred. The second insulating layer914is made of inorganic insulating material such as silicon oxide (SiOx) and silicon nitride (SiNx), and/or organic insulating material such as photo acryl.

A first contact hole912aand a second contact hole912are formed on each of the first and second insulating layers912and914over the thin film transistor Tr and the second electrode911and exposes the drain electrode (not shown) of the thin film transistor Tr and the second electrode911. Also, a third contact hole916aand a fourth contact hole916bare formed on the second insulating layer914over each of the p-type electrode981and the n-type electrode983of the micro LED980, and thereby the p-type electrode981and the n-type electrode983are exposed externally.

A first connection electrode918aand a second connection electrode918bmade of transparent metal oxide such as ITO, IGZO and/or IZO are formed on the second insulating layer914. The drain electrode (not shown) and the p-type electrode981of the micro LED980are electrically interconnected through the first and third contact holes912aand816a, and the second electrode911and the n-type electrode983of the micro LED980are electrically interconnected through the second and third contact holes912band916b.

Also, a reflective insulating film919is formed over the first substrate910including the connection electrodes918aand918b. The reflective insulating film919is disposed to encapsulate the outer periphery of each micro LED980. The reflective insulating film919reflects a light laterally emitted from the micro LED980among the light emitted from the respective micro LED980to an upper plane of the first substrate910in order to improve the out-coupling efficiency of the micro LED980. The reflective insulating film919can be made of insulating material including fine particles for light reflection, for example, may be made of, but is not limited to, an insulating material of silicon oxide (SiOx) or silicon nitride (SiNx) in which titanium oxide (TiO2) particles are dispersed.

The color filter layer920may be disposed on or over the second substrate970and includes a red color filter pattern (R-CF)922and a green color filter pattern (G-CF)924each of which corresponds to the red, and green pixel regions Rp and Gp, respectively. In the blue pixel region Bp, the color filter pattern920is not positioned. The blue (B) light emitted from the micro LED980in each of the red and green pixel regions Rp and Gp passes through each of the red and green color filter patterns922and924, respectively, and then each of red and green lights is passed through the second substrate970in the respective pixel regions Rp and Gp, while the blue light is passes through the second substrate970in the blue pixel region Bp.

When only the color filter layer920is disposed between the second substrate970and the micro LED980, only the light of specific wavelength ranges among the blue (B) light emitted from the micro LED980can transmit to the second substrate970in each of the red and green pixel regions Rp and Gp. In other words, only the light of red wavelength ranges can pass through the red pixel region Rp and only the light of green wavelength ranges can pass through the green pixel region Gp, thus the out-coupling efficiency of the micro LED980may be deteriorated.

The color conversion layer930including the dispersant150adsorbed on the surface of the inorganic luminescent particles100aand100bis positioned on the color filter layer920. More particularly, the color conversion layer930includes a red color conversion layer932positioned on the red color filter pattern822corresponding to the red pixel region Rp, and a green color conversion layer934positioned on the green color filter pattern924corresponding to the green pixel region Gp. But, the color conversion layer930is not positioned in the blue pixel region Bp.

The red color conversion layer932includes the dispersant150adsorbed on the surface of the red inorganic luminescent particle100a. The blue (B) light emitted from the micro LED980in the red pixel region Rp passes through the red color conversion layer932and is converted into the red (R) light, and then the converted red (R) light passes through the red color filter pattern932to emit an intended red (R) light. Some blue (B) light that is not converted in passing through the red color conversion layer932may be absorbed in the red color filter pattern922. Since most of the blue (B) light emitted from the micro LED D980in the red pixel region Rp passes through the red color filter pattern922in a state converted to red wavelength light, the light amount absorbed in the red color filter pattern922is reduced, and thereby improving out-coupling efficiency.

The green color conversion layer934includes the dispersant150adsorbed on the surface of the green inorganic luminescent particle100b. The blue (B) light emitted from the micro LED980in the green pixel region Gp passes through the green color conversion layer934and is converted into the green (G) light, and then the converted green (G) light passes through the green color filter pattern934to emit an intended green (R) light. Some blue (B) light that is not converted in passing through the green color conversion layer934may be absorbed in the green color filter pattern924. Since most of the blue (B) light emitted from the micro LED980in the green pixel region Gp passes through the green color filter pattern924in a state converted to green wavelength light, the light amount absorbed in the green color filter pattern924is reduced, and thereby improving out-coupling efficiency.

The blue (B) light emitted from the micro LED980in the blue pixel region Bp transmits as it is, and therefore, both the color filter pattern920and the color conversion layer930are not positioned in the blue pixel region Bp.

Since each of the color conversion layers932and934includes the dispersant150adsorbed stably on the surface of the inorganic luminescent particles100aand100b, the inorganic luminescent particles100aand100bcan maintain their luminous properties. As the light conversion efficiency in the color conversion layer930is improved, light leakage in the color conversion layer930is minimized, thus luminance of light emitted from the micro LED980is not lowered. When the color conversion layer930is disposed, the color filter layer920may be omitted.

In an alternative aspect, the color conversion layer930may be positioned over the whole red and green pixel regions Rp and Gp, and may comprise a single color conversion layer comprising the dispersant150adsorbed on a surface of red-green inorganic luminescent particles. Also, the color conversion layer may be positioned in the whole red and green pixel regions Rp and Gp except the blue pixel region Bp. In this case, a single color conversion layer may comprise the dispersant150adsorbed on the surface of the red inorganic luminescent particle100a.

In another exemplary aspect, the light emitting display device900may be a bottom-type. In this case, the color filter layer may be positioned on or over the first substrate910and the color conversion layer may be positioned between the color filter layer and the micro LED.

Synthesis Example 1: Synthesis of Polyurethane-Based Dispersant Having Pillar Structure

A polyurethane-based dispersant having the pillar structure on a side chain was synthesized as follows: Polyethylene glycol monomethyl ether (PEG monomethyl ether, MW=200 g/mol, 400 mg, 2.00 mmol) as an alcohol precursor and an aliphatic diol, 1,1-hexadecanediol (2.65 mmol) were dissolved in anhydrous tetrahydrofuran (THF, 10 mL). 1,6-hexamethylene diisocyanate (HDI, 614 mg, 3.65 mmol) anc 1,4-diazabicyclo octane (DABCO, 12.1 mg, 0.061 mmol) and triethyl amine as a catalyst were added into the reactants, and the materials were reacted at 75° C. for 7 hours under nitrogen atmosphere until the solution becomes transparently viscous, that is urethane polymerization reaction initiates with stirring. After the mixture was cooled down to a room temperature, excessive amount of diethyl ether was added to precipitate the polyurethane having the pillar structure.

Synthesis Examples 2-4: Synthesis of Polyurethane-Based Dispersant Having Pillar Structure

Polyurethane-based dispersants were synthesized in the same manner as Synthesis Example 1, except using 1,1-heptane diol (Synthesis Example 2), 1,1-decane diol (Synthesis Example 3) or 1,1-octadecane diol (Synthesis Example 4) as the aliphatic diol instead of 1,1-hexadecane diol.

Polyurethane-based dispersants were synthesized in the same manner as Synthesis Example 1, except using 1,2-hexadecane diol (Comparative Synthesis Example 1), 1,2-heptane diol (Comparative Synthesis Example 2), 1,2-decane diol (Comparative Synthesis Example 3) or 1,2-octadecane diol (Comparative Synthesis Example 4), which has not 1,1-diol structure, as the aliphatic diol instead of 1,1-hexadecane diol.

Polyurethane-based dispersants were synthesized in the same manner as Synthesis Example 1, except using 1,3-hexadecane diol (Comparative Synthesis Example 5), 1,3-heptane diol (Comparative Synthesis Example 6), 1,3-decane diol (Comparative Synthesis Example 7) or 1,3-octadecane diol (Comparative Synthesis Example 8), which has not 1,1-diol structure, as the aliphatic diol instead of 1,1-hexadecane diol.

Polyurethane-based dispersants were synthesized in the same manner as Synthesis Example 1, except using 1,ω-hexadecane diol (Comparative Synthesis Example 9), 1,ω-heptane diol (Comparative Synthesis Example 10, 1,ω-decane diol (Comparative Synthesis Example 11) or 1,ω-octadecane diol (Comparative Synthesis Example 12), which has not 1,1-diol structure, as the aliphatic diol instead of 1,1-hexadecane diol.

Evaluation Dispersion Property in Polar Solvents

The polyurethane-based dispersants using 1,2-alkane diols in Synthesis Examples 1-4 and the polyurethane-based dispersants using diols in Ref 1-12 were added into a polar solvent, propylene glycol monomethyl ether acetate (PGMEA) and then evaluated their dispersion properties in the polar solvent. Table 1 below indicates the results of dispersion properties for the dispersants andFIG.13illustrates dispersion degrees of the dispersants in Synthesis Examples 1-4 in the polar solvent. As indicated in Table 1, compared to the dispersants in Ref. 1-12, the dispersants in Synthesis Examples have improved dispersion properties in the polar solvent, PGMEA.

Measurement of QY of QD Dispersed in Dispersants

A quantum yield (QY) of a green quantum dot (InP/ZnSe, linked by organic ligand of aliphatic acid amino, photoluminescence peak: 530-535 nm) prior to dispersing the dispersants (initial QY) was measured, and then the QY of the quantum dots dispersed in each of the polyurethane-based dispersants of Synthesis Examples 1-4, the polyurethane-based dispersants of Ref. 1-12 and the convention dispersant without any pillar structure, and the QY of the quantum dots dispersed in each of the dispersants were measured to evaluate the QY differences compared to the QY of the initial quantum dot (prior to dispersing). Table 2 andFIG.14illustrate the measurement results. The quantum dots dispersed in the polyurethane-based dispersants into which the pillar structure was applied by using 1,1-alkane diols in Synthesis Examples 1-4 maintained relatively high QY. Particularly, the quantum dot dispersed in the polyurethane-based dispersant having the pillar structure derived from 1,1-hexadecane diol in Synthesis Example 1 maintained its QY substantially identical as the initial quantum dot.

Evaluation Thermal Resistance of QD Film

Mixtures of each of the polyurethane-based dispersant in Synthesis Examples 1-4, the polyurethane-based dispersant in Ref. 1-12 and the conventional dispersant, a quantum dot (InP/ZnSe, linked by organic ligand of aliphatic acid amino, photoluminescence peak: 530-535 nm) and an organic solvent was applied into a bare glass using a spin-coating, performed a soft baking at 80° C. for 5 minutes and then initial EQE (external quantum efficiency) for each film was measured. In order to evaluate the thermal resistance, a hard baking was performed for each film in an oven at 180° C. for 6 hours in air. EQE for each of the hard-baked film was measured again and compared to the initial EQE. Table 3 andFIG.15illustrate the results. The quantum dots dispersed in the polyurethane-based dispersants into which the pillar structure was applied by using 1,1-alkane diols in Synthesis Examples 1-4 maintained relatively high EQE. Particularly, the quantum dot dispersed in the polyurethane-based dispersant having the pillar structure derived from 1,1-hexadecane diol in Synthesis Example 1 maintained its EQE substantially identical as the initial quantum dot. These results indicate that the dispersant in Synthesis Examples 1-4 enables the quantum dot to improve their thermal property.

TABLE 3EQE Changes of Quantum DotEQE (%, Compared to Initial value)heptanesdecanehexadecaneoctadecaneSampledioldioldioldiol1,1-diol20→13(62%)24→17(71%)25→23(94%)22→14(64%)1,2-diol20→9(45%)19→10(53%)20→10(50%)19→10(53%)1,3-diol18→6(33%)20→9(45%)21→9(43%)19→8(42%)1,ω-diol21→11(52%)21→11(52%)19→10(53%)18→8(44%)no pillar18→10 (55%)

It will be apparent to those skilled in the art that various modifications and variations can be made in the dispersant, the light emitting film, the light emitting diode and light emitting device including the dispersant of the present disclosure without departing from the technical idea or scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.