Quantum dot composite, light emitting element comprising quantum dot composite, and display device comprising quantum dot composite

Abstract

This quantum dot composite comprises: a quantum dot; a first ligand which is bonded to the surface of the quantum dot and includes a thiol group at one end thereof; and a second ligand which is bonded to the surface of the quantum dot and includes a thiol group at one end thereof and a carboxyl group at the other end thereof.

Description

Quantum dot composite, light-emitting device including quantum dot composite, and display device including quantum dot composite

[0001] The present invention relates to a quantum dot complex, a light-emitting device including a quantum dot complex, and a display device including a quantum dot complex.

[0002] A variety of display devices are being developed for use in multimedia electronic devices such as televisions, mobile phones, tablets, navigation systems, and game consoles. These display devices include so-called self-luminous light-emitting elements that emit light to display information.

[0003] Among light-emitting devices, quantum dot light-emitting devices containing quantum dots in their light-emitting layers exhibit high color purity, high luminous efficiency, and multicolorization. Meanwhile, research is being conducted on the materials of the light-emitting layer and the stacking characteristics of adjacent functional layers to maintain this superior luminous quality.

[0004] An object of the present invention is to provide a quantum dot composite having good quantum yield characteristics and capable of improving interface characteristics with an adjacent layer.

[0005] An object of the present invention is to provide a light-emitting device having improved reliability by having good quantum yield characteristics and improved interface characteristics with an adjacent functional layer.

[0006] In addition, it is an object of the present invention to provide a display device having excellent display quality characteristics including a quantum dot complex.

[0007] One embodiment provides a quantum dot complex comprising: a quantum dot; a first ligand that binds to the surface of the quantum dot and includes a thiol group at one end; and a second ligand that is different from the first ligand and that binds to the surface of the quantum dot and includes a thiol group at one end and a carboxyl group at the other end.

[0008] The first ligand may include a first head portion comprising a thiol group, and a first tail portion extending from the first head portion and comprising an alkyl group.

[0009] The above first tail portion may include an alkyl group having 2 to 20 carbon atoms.

[0010] The second ligand may include a second head portion comprising a thiol group, a terminal portion spaced from the surface of the anode point and comprising a carboxyl group, and a second tail portion disposed between the second head portion and the terminal portion.

[0011] The above second ligand can be represented by the following chemical formula 1.

[0012] [Chemical Formula 1]

[0013]

[0014] In the above chemical formula 1, n is an integer of 1 to 20, and R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0015] The second ligand may comprise at least one of the following compounds LD1 to LD4.

[0016]

[0017] The weight ratio of the first ligand and the second ligand may be 99:1 to 50:50.

[0018] The quantum dot includes a core and a shell surrounding the core, and each of the first ligand and the second ligand can be bound to the surface of the shell.

[0019] The core includes a first semiconductor nanocrystal, and the shell includes a second semiconductor nanocrystal different from the first semiconductor nanocrystal, wherein each of the first semiconductor nanocrystal and the second semiconductor nanocrystal may be selected from a group II-VI compound, a group III-VI compound, a group I-III-VI compound, a group III-V compound, a group III-II-V compound, a group IV-VI compound, a group IV element, a group IV compound, and a combination thereof.

[0020] The above quantum dot may include two or more elements selected from elements of Group II and Group VI, excluding Cd.

[0021] The above quantum dots may include ZnSeTe.

[0022] It can absorb light of 300 nm to 450 nm.

[0023] Another embodiment provides a light-emitting device comprising: a first electrode; a second electrode facing the first electrode; an emitting layer disposed between the first electrode and the second electrode and including a quantum dot complex; and a functional layer disposed at least one of between the emitting layer and the first electrode and between the emitting layer and the second electrode; wherein the quantum dot complex comprises: a quantum dot; a first ligand that is bound to a surface of the quantum dot and includes a thiol group at one end; and a second ligand that is different from the first ligand and is bound to a surface of the quantum dot and includes a thiol group at one end and a carboxyl group at the other end.

[0024] The first ligand may include a first head portion comprising a thiol group, and a first tail portion extending from the first head portion and comprising an alkyl group, and the second ligand may include a second head portion comprising a thiol group, a terminal portion spaced from the surface of the cation point and comprising a carboxyl group, and a second tail portion disposed between the second head portion and the terminal portion.

[0025] The above second ligand can be represented by the following chemical formula 1.

[0026] [Chemical Formula 1]

[0027]

[0028] In the above chemical formula 1, n is an integer of 1 to 20, and R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0029] The second ligand may comprise at least one of the following compounds LD1 to LD4.

[0030]

[0031] The functional layer includes a first functional layer disposed between the first electrode and the light-emitting layer; and a second functional layer disposed between the light-emitting layer and the second electrode; wherein one of the first functional layer and the second functional layer may be a hole transport region, and the other may be an electron transport region.

[0032] The functional layer includes a hole transport region disposed below the light-emitting layer and an electron transport region disposed above the light-emitting layer, and the electron transport region is formed from a common layer composition including an electron transport material and an organic solvent, and a contact angle of the organic solvent with respect to the light-emitting layer may be 15 degrees or less.

[0033] Another embodiment provides a display device including a circuit layer; and a display element layer disposed on the circuit layer and including a pixel defining film defining a light emitting element and a pixel opening; wherein the light emitting element comprises a first electrode; a second electrode facing the first electrode; an emission layer disposed between the first electrode and the second electrode and including a quantum dot complex; and a functional layer disposed at least one of between the emission layer and the first electrode and between the emission layer and the second electrode; wherein the quantum dot complex comprises a quantum dot; a first ligand that is bound to a surface of the quantum dot and includes a thiol group at one end; and a second ligand that is different from the first ligand and is bound to a surface of the quantum dot and includes a thiol group at one end and a carboxyl group at the other end.

[0034] The first ligand may include a first head portion comprising a thiol group, and a first tail portion extending from the first head portion and comprising an alkyl group, and the second ligand may include a second head portion comprising a thiol group, a terminal portion spaced from the surface of the cation point and comprising a carboxyl group, and a second tail portion disposed between the second head portion and the terminal portion.

[0035] The above second ligand can be represented by the following chemical formula 1.

[0036] [Chemical Formula 1]

[0037]

[0038] In the above chemical formula 1, n is an integer of 1 to 20, and R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0039] The second ligand may comprise at least one of the following compounds LD1 to LD4.

[0040]

[0041] The functional layer includes a first functional layer disposed between the first electrode and the light-emitting layer; and a second functional layer disposed between the light-emitting layer and the second electrode; wherein one of the first functional layer and the second functional layer may be a hole transport region, and the other may be an electron transport region.

[0042] The above light-emitting layer is disposed within the pixel opening, and the functional layer may be a common layer overlapping the light-emitting layer and the pixel defining film.

[0043] The light-emitting element includes a first light-emitting element including a first light-emitting layer emitting blue light, a second light-emitting element including a second light-emitting layer emitting green light, and a third light-emitting element including a third light-emitting layer emitting red light, and at least one of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer may include the quantum dot complex.

[0044] A quantum dot complex of one embodiment can exhibit excellent wetting properties of adjacent layer materials without changes in optical properties by including two different types of ligands.

[0045] A light-emitting device of one embodiment includes a quantum dot complex in which two types of ligands are bonded to a light-emitting layer, and thus can have excellent film properties of the light-emitting layer and excellent interface properties between the light-emitting layer and a functional layer adjacent thereto, thereby exhibiting good optical properties and excellent device quality.

[0046] A display device of one embodiment can exhibit excellent display quality by including a light-emitting element including a quantum dot complex in which two types of ligands are bonded to a light-emitting layer.

[0047] Figure 1 is a perspective view showing a display device of one embodiment.

[0048] Fig. 2 is a cross-sectional view showing a portion corresponding to line I-I' of Fig. 1.

[0049] Figure 3 is a plan view showing a display device of one embodiment.

[0050] Fig. 4 is a cross-sectional view showing a portion corresponding to line II-II' of Fig. 3.

[0051] Figure 5a is a cross-sectional view showing a light emitting element of one embodiment.

[0052] Figure 5b is a cross-sectional view showing a light emitting element of one embodiment.

[0053] Figure 6 is a schematic diagram showing the structure of a quantum dot complex of one embodiment.

[0054] FIG. 7a is a schematic diagram showing an enlarged portion of a quantum dot complex according to one embodiment.

[0055] FIG. 7b is a schematic diagram showing an enlarged portion of a quantum dot complex according to one embodiment.

[0056] FIG. 8a is a diagram showing the optical properties and luminescence properties of a solution containing a quantum dot complex of one embodiment.

[0057] FIG. 8b is a drawing showing the luminescence characteristics of a film state including a quantum dot complex of one embodiment.

[0058] The present invention is susceptible to various modifications and takes various forms. Specific embodiments are illustrated in the drawings and described in detail herein. However, this is not intended to limit the present invention to specific disclosed forms, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0059] In this specification, when it is said that a component (or region, layer, portion, etc.) is “on,” “connected to,” or “coupled to” another component, it means that it can be directly disposed / connected / coupled to the other component, or a third component may be disposed between them.

[0060] Identical drawing numbers indicate identical components. Furthermore, in the drawings, the thicknesses, proportions, and dimensions of components are exaggerated for the purpose of effectively illustrating the technical content. "And / or" encompasses any combination of one or more of the associated components.

[0061] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a "second component," and similarly, a second component may also be referred to as a "first component." Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0062] Additionally, terms such as "below," "lower," "above," and "upper" are used to describe the relationships between components depicted in the drawings. These terms are relative concepts and are described based on the directions indicated in the drawings.

[0063] It should be understood that terms such as "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0064] In this specification, “Group” refers to a group of the IUPAC Periodic Table.

[0065] In this specification, “Group II” may include Group IIA elements and Group IIB elements. For example, the Group II element may be, but is not limited to, magnesium (Mg) or zinc (Zn).

[0066] As used herein, “Group III” may include Group IIIA elements and Group IIIB elements. For example, a Group III element may be, but is not limited to, aluminum (Al), indium (In), gallium (Ga), or titanium (Ti).

[0067] In this specification, "Group V" may include Group VA elements and Group VB elements. For example, the Group V element may be, but is not limited to, phosphorus (P), arsenic (As), or antimony (Sb).

[0068] In this specification, "Group VI" may include Group VIA elements and Group VIB elements. For example, the Group VI elements may be, but are not limited to, oxygen (O), sulfur (S), selenium (Se), or tellurium (Te).

[0069] In this specification, "substituted or unsubstituted" may mean substituted or unsubstituted with one or more substituents selected from the group consisting of a deuterium atom, a halogen atom, a cyano group, a nitro group, an amine group, a silyl group, an oxy group, a thio group, a sulfinyl group, a sulfonyl group, a carbonyl group, a boron group, a phosphine oxide group, a phosphine sulfide group, an alkyl group, an alkenyl group, an alkynyl group, a hydrocarbon ring group, an aryl group, and a heterocyclic group. In addition, each of the above-mentioned exemplified substituents may be substituted or unsubstituted. For example, a biphenyl group may be interpreted as an aryl group, or may be interpreted as a phenyl group substituted with a phenyl group.

[0070] In this specification, the alkyl group may be linear or branched. The number of carbon atoms in the alkyl group may be 1 to 60, 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 6. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, i-butyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, t-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl group, n-nonyl group, n-decyl group, adamantyl group, 2-ethyldecyl group, 2-butyldecyl group, 2-hexyldecyl group, 2-octyldecyl group, n-undecyl group, n-dodecyl group, 2-ethyldodecyl group, 2-butyldodecyl group, 2-hexyldodecyl group, 2-octyldodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, 2-ethylhexadecyl group, 2-butylhexadecyl group, 2-hexylhexadecyl group, 2-octylhexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group, 2-ethylicosyl group, 2-butylicosyl group, Examples thereof include, but are not limited to, 2-hexylicosyl group, 2-octylicosyl group, n-henicosyl group, n-docosyl group, n-tricosyl group, n-tetracosyl group, n-pentacosyl group, n-hexacosyl group, n-heptacosyl group, n-octacosyl group, n-nonacosyl group, and n-triacontyl group.

[0071] In the present specification, the carbon number of the amine group is not particularly limited, but may be 1 to 30, 1 to 20, or 1 to 10. The amine group may include an alkyl amine group and an aryl amine group. Examples of the amine group include, but are not limited to, a methylamine group, a dimethylamine group, a phenylamine group, a diphenylamine group, a naphthylamine group, and a 9-methyl-anthracenylamine group.

[0072] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. Furthermore, terms defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an overly idealistic or overly formal sense unless explicitly defined herein.

[0073] Hereinafter, a quantum dot composite, a light-emitting element, and a display device according to one embodiment of the present invention will be described with reference to the drawings.

[0074] FIG. 1 is a perspective view illustrating a display device according to one embodiment. The display device (DD) of one embodiment may be a device activated by an electrical signal. For example, the display device (DD) may be a large-sized device such as a television, a monitor, or an outdoor billboard. Furthermore, the display device (DD) may be a small- to medium-sized device such as a personal computer, a laptop computer, a personal digital assistant, an automobile navigation unit, a game console, a smartphone, a tablet, or a camera. Furthermore, these are merely examples and may be employed in other electronic devices without departing from the scope of the present invention.

[0075] A display device (DD) can display an image (or video) through a display surface (DD-IS). The display surface (DD-IS) can be parallel to a plane defined by a first direction (DR1) and a second direction (DR2). The display surface (DD-IS) can include a display area (DA) and a non-display area (NDA).

[0076] Pixels (PX) may be arranged in the display area (DA). The non-display area (NDA) may be a portion where pixels (PX) are not arranged. The non-display area (NDA) may be defined along the edge of the display surface (DD-IS). The non-display area (NDA) may surround the display area (DA). However, the embodiment is not limited thereto, and the non-display area (NDA) may be omitted or may be arranged on only one side of the display area (DA).

[0077] Although Fig. 1 illustrates a display device (DD) having a flat display surface (DD-IS), the embodiment is not limited thereto. The display device (DD) may include a curved display surface or a three-dimensional display surface. The three-dimensional display surface may include a plurality of display areas pointing in different directions.

[0078] In FIG. 1 and the drawings below, a first direction axis (DR1) to a third direction axis (DR3) are illustrated, and the directions indicated by the first to third direction axes (DR1, DR2, DR3) described in this specification are relative concepts and can be converted into other directions. In addition, the directions indicated by the first to third direction axes (DR1, DR2, DR3) can be described as the first to third directions, and the same drawing reference numerals can be used. In this specification, the first direction axis (DR1) and the second direction axis (DR2) are orthogonal to each other, and the third direction axis (DR3) can be a normal direction with respect to a plane defined by the first direction axis (DR1) and the second direction axis (DR2). In this specification, 'plane' means a plane defined by a first direction axis (DR1) and a second direction axis (DR2), and 'cross-section' means a plane that is perpendicular to the plane defined by the first direction axis (DR1) and the second direction axis (DR2) and parallel to the third direction axis (DR3). The thickness direction of the display device (DD) may be a direction parallel to the third direction (DR3), which is a normal direction to the plane defined by the first direction (DR1) and the second direction (DR2).

[0079] In this specification, the upper surface (or front surface) and the lower surface (or back surface) of the members constituting the display device (DD) may be defined with reference to the third direction (DR3). More specifically, among two surfaces of one member facing each other with reference to the third direction (DR3), the surface that is relatively close to the display surface (DD-IS) may be defined as the front surface (or upper surface), and the surface that is relatively spaced from the display surface (DD-IS) may be defined as the back surface (or lower surface). In addition, in this specification, the upper surface (or upper side) and the lower surface (or lower side) may be defined with reference to the third direction (DR3), and the upper surface (or upper side) may be defined in a direction approaching the display surface (DD-IS), and the lower surface (or lower side) may be defined in a direction away from the display surface (DD-IS).

[0080] In this specification, when a component is "directly disposed / directly formed" on another component, it means that no third component is disposed between the component and the other component. In other words, when a component is "directly disposed / directly formed" on another component, it means that the component and the other component are in "contact."

[0081] Fig. 2 is a cross-sectional view showing a portion corresponding to line I-I' of Fig. 1. Fig. 2 may be a cross-sectional view of a display device according to one embodiment.

[0082] A display device (DD) may include a display panel (DP) and an optical structure layer (PP) disposed on the display panel (DP). The display panel (DP) may include a display element layer (DP-EL). The display element layer (DP-EL) may include a light emitting element (ED, FIG. 4). In addition, the display panel (DP) may include an encapsulation layer (TFE) disposed on the display element layer (DP-EL). The encapsulation layer (TFE) may be disposed directly on the display element layer (DP-EL) or may be coupled to the display element layer (DP-EL) through a separate member.

[0083] An optical structure layer (PP) is disposed on a display panel (DP) to control light reflected from the display panel (DP) due to external light. The optical structure layer (PP) may be a reflection reduction layer that reduces reflectance due to external light. For example, the optical structure layer (PP) may include a polarizing film including a phase retarder and / or a polarizer, multilayer reflective layers that destructively interfere with reflected light, or color filters arranged in response to the pixel arrangement and emission color of the display panel (DP). When the optical structure layer (PP) includes color filters, the color filters may be arranged in consideration of the emission colors of pixels included in the display panel (DP). Additionally, in one embodiment, the optical structure layer (PP) may be omitted.

[0084] The display panel (DP) may be a configuration that actually generates an image. In one embodiment of the display device (DD), the display panel (DP) may be an emissive display panel. For example, the display panel (DP) may be a quantum dot emissive display panel including a quantum dot emissive element. However, the embodiment is not limited thereto.

[0085] The display panel (DP) may include a base substrate (BS), a circuit layer (DP-CL) disposed on the base substrate (BS), and a display element layer (DP-EL) disposed on the circuit layer (DP-CL).

[0086] Fig. 3 is a plan view of a display device according to one embodiment. Fig. 4 is a cross-sectional view showing a portion corresponding to line II-II' of Fig. 3. Fig. 4 may be a cross-sectional view showing a display device according to one embodiment.

[0087] Referring to FIGS. 3 and 4, the display device (DD) may include a plurality of light-emitting areas (PXA-B, PXA-G, PXA-R) repeatedly arranged throughout the display area (DA, FIG. 1). The display device (DD) of one embodiment may include first to third light-emitting areas (PXA-B, PXA-G, PXA-R) that are distinct from each other. In addition, the display device (DD) may include a peripheral area (NPXA) arranged around the first to third light-emitting areas (PXA-B, PXA-G, PXA-R). The peripheral area (NPXA) sets a boundary of the first to third light-emitting areas (PXA-B, PXA-G, PXA-R). The peripheral area (NPXA) may surround the first to third light-emitting areas (PXA-B, PXA-G, PXA-R). A structure that prevents color mixing between the first to third light-emitting regions (PXA-B, PXA-G, PXA-R), such as a pixel defining layer (PDL), may be placed in the peripheral region (NPXA).

[0088] The pixel defining layer (PDL) may define the light-emitting areas (PXA-B, PXA-G, PXA-R). The light-emitting areas (PXA-B, PXA-G, PXA-R) and the peripheral area (NPXA) may be distinguished by the pixel defining layer (PDL).

[0089] A display panel (DP) according to one embodiment may include a plurality of light-emitting elements (ED-1, ED-2, ED-3) that emit light in different wavelength ranges. The plurality of light-emitting elements (ED-1, ED-2, ED-3) may emit light of different colors. For example, the display panel (DP) may include a first light-emitting element (ED-1) that emits blue light, a second light-emitting element (ED-2) that emits green light, and a third light-emitting element (ED-3) that emits red light. However, the embodiment is not limited thereto, and the first to third light-emitting elements (ED-1, ED-2, ED-3) may emit light in the same wavelength range, or at least one may emit light in a different wavelength range.

[0090] Each of the light-emitting regions (PXA-B, PXA-G, PXA-R) may be a region in which light generated from each of the light-emitting elements (ED-1, ED-2, ED-3) is emitted. In FIGS. 3 and 4, first to third light-emitting regions (PXA-B, PXA-G, PXA-R) emitting blue light, green light, and red light, respectively, are illustrated as examples. For example, the display device (DD) of one embodiment may include a first light-emitting region (PXA-B) emitting blue light, a second light-emitting region (PXA-G) emitting green light, and a third light-emitting region (PXA-R) emitting red light, which are distinct from each other.

[0091] In the display device (DD) of one embodiment illustrated in FIGS. 3 and 4, the light-emitting regions (PXA-B, PXA-G, PXA-R) may have different areas depending on the color emitted from the light-emitting layers (EML-B, EML-G, EML-R) of the light-emitting elements (ED-1, ED-2, ED-3). In FIG. 3, first to third light-emitting regions (PXA-B, PXA-G, PXA-R) having the same planar shape and different planar areas are exemplarily illustrated, but the embodiment is not limited thereto.

[0092] The first light-emitting region (PXA-B) corresponding to the first light-emitting element (ED-1) emitting blue light may have the largest area, and the second light-emitting region (PXA-G) corresponding to the second light-emitting element (ED-2) emitting green light may have the smallest area. However, the embodiment is not limited thereto, and the first to third light-emitting regions (PXA-B, PXA-G, PXA-R) may emit light of a color other than blue light, green light, and red light. Alternatively, the first to third light-emitting regions (PXA-B, PXA-G, PXA-R) may have the same area, or the light-emitting regions (PXA-B, PXA-G, PXA-R) may be provided with an area ratio different from that illustrated in FIG. 3. The areas of the first to third light-emitting regions (PXA-B, PXA-G, PXA-R) may be set according to the light-emitting color. In this case, area can mean the area on a plane.

[0093] The first light-emitting region (PXA-B) and the third light-emitting region (PXA-R) may be arranged alternately along the first direction axis (DR1) to form a first group (PXG1). The second light-emitting region (PXA-G) may be arranged along the first direction axis (DR1) to form a second group (PXG2). The first group (PXG1) may be arranged spaced apart from the second group (PXG2) in the direction of the second direction axis (DR2). Each of the first group (PXG1) and the second group (PXG2) may be provided in plural. The first groups (PXG1) and the second groups (PXG2) may be arranged alternately along the second direction axis (DR2).

[0094] One third light-emitting region (PXA-R) can be arranged spaced apart from one second light-emitting region (PXA-G) in the direction of a fourth direction axis (DR4). One first light-emitting region (PXA-B) can be arranged spaced apart from one second light-emitting region (PXA-G) in the direction of a fifth direction axis (DR5). The direction of the fourth direction axis (DR4) can be a direction between the direction of the first direction axis (DR1) and the direction of the second direction axis (DR2). The fifth direction axis (DR5) can be a direction intersecting the fourth direction axis (DR4) and inclined with respect to the second direction axis (DR2).

[0095] Meanwhile, the arrangement structure of the light-emitting regions (PXA-B, PXA-G, PXA-R) is not limited to the arrangement structure illustrated in FIG. 3. For example, in the light-emitting regions (PXA-B, PXA-G, PXA-R), the first light-emitting region (PXA-B), the second light-emitting region (PXA-G), and the third light-emitting region (PXA-R) may be arranged sequentially and alternately along the first direction axis (DR1). In addition, the shapes of the light-emitting regions (PXA-B, PXA-G, PXA-R) on a plane are not limited to those illustrated, and may be defined as shapes different from those illustrated.

[0096] Referring to FIG. 4, the display device (DD) may include a display panel (DP) and an optical structure layer (PP) stacked in the third direction axis (DR3). The display panel (DP) may include a base substrate (BS), a circuit layer (DP-CL) provided on the base substrate (BS), and a display element layer (DP-EL). The display element layer (DP-EL) may include a light-emitting element (ED) disposed between pixel defining layers (PDL) or on the pixel defining layers (PDL), and an encapsulation layer (TFE) disposed on the light-emitting element (ED).

[0097] The base substrate (BS) may be a member that provides a base surface on which the display element layer (DP-EL) is placed. The base substrate (BS) may be a glass substrate, a metal substrate, a plastic substrate, or the like. However, the embodiment is not limited thereto, and the base substrate (BS) may be an inorganic layer, an organic layer, or a composite material layer.

[0098] The base substrate (BS) may include a single-layer or multi-layer structure. For example, the base substrate (BS) may include a first synthetic resin layer, an intermediate layer having a multi-layer or single-layer structure, and a second synthetic resin layer, which are sequentially laminated. The intermediate layer may be referred to as a base barrier layer. The intermediate layer may include, but is not particularly limited to, a silicon oxide (SiOx) layer and an amorphous silicon (a-Si) layer disposed on the silicon oxide layer. For example, the intermediate layer may include at least one of a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, and an amorphous silicon layer. The base substrate (BS) may be a flexible substrate that can be easily bent or folded.

[0099] Each of the first and second synthetic resin layers may include a polyimide-based resin. In addition, each of the first and second synthetic resin layers may include at least one of an acrylate-based resin, a methacrylate-based resin, a polyisoprene-based resin, a vinyl-based resin, an epoxy-based resin, a urethane-based resin, a cellulose-based resin, a siloxane-based resin, a polyamide-based resin, and a perylene-based resin. In the present specification, the "~~"-based resin means one that includes a "~~" functional group.

[0100] In one embodiment, the circuit layer (DP-CL) is disposed on the base substrate (BS), and the circuit layer (DP-CL) may include a plurality of transistors (not shown). The transistors (not shown) may each include a control electrode, an input electrode, and an output electrode. For example, the circuit layer (DP-CL) may include a switching transistor and a driving transistor for driving a light-emitting element (ED) of the display element layer (DP-EL).

[0101] A display element layer (DP-EL) may be arranged on a circuit layer (DP-CL). The display element layer (DP-EL) may include a pixel defining layer (PDL), and first to third light-emitting elements (ED-1, ED-2, ED-3) separated by the pixel defining layer (PDL). The light-emitting elements (ED-1, ED-2, ED-3) of the display element layer (DP-EL) are electrically connected to driving elements of the circuit layer (DP-CL), and may generate light according to signals provided by the driving elements to display an image.

[0102] An encapsulation layer (TFE) may be disposed on the display element layer (DP-EL). The encapsulation layer (TFE) may protect the display element layer (DP-EL) from foreign substances such as moisture, oxygen, and dust particles. The encapsulation layer (TFE) may seal the light emitting elements (ED) of the display element layer (DP-EL). The encapsulation layer (TFE) may include at least one thin film for improving the optical efficiency of the display element layer (DP-EL) or protecting the display element layer (DP-EL). The encapsulation layer (TFE) may include at least one inorganic layer. The encapsulation layer (TFE) may include a structure in which an inorganic layer, an organic layer, and an inorganic layer are sequentially stacked.

[0103] The pixel defining layer (PDL) may be formed of a polymer resin. For example, the pixel defining layer (PDL) may be formed by including a polyacrylate-based resin or a polyimide-based resin. In addition, the pixel defining layer (PDL) may be formed by including an inorganic material in addition to the polymer resin. Meanwhile, the pixel defining layer (PDL) may be formed by including a light absorbing material, or may be formed by including a black pigment or a black dye. A pixel defining layer (PDL) formed by including a black pigment or a black dye can implement a black pixel defining layer. Carbon black or the like may be used as the black pigment or black dye when forming the pixel defining layer (PDL), but the embodiment is not limited thereto.

[0104] Additionally, the pixel defining layer (PDL) may be formed of an inorganic material. For example, the pixel defining layer (PDL) may be formed of an inorganic material such as silicon nitride (SiNx), silicon oxide (SiOx), or silicon nitride (SiOxNy).

[0105] A pixel aperture (OH) may be defined in the pixel defining layer (PDL). A portion of the first electrode (EL1) may be exposed in the pixel aperture (OH). The portion corresponding to the first electrode (EL1) exposed in the pixel aperture (OH) may be defined as light-emitting regions (PXA-B, PXA-G, PXA-R). However, the embodiment is not limited thereto.

[0106] The pixel defining layer (PDL) may distinguish the first to third light-emitting elements (ED-1, ED-2, ED-3). The light-emitting layers (EML-B, EML-G, EML-R) of the first to third light-emitting elements (ED-1, ED-2, ED-3) may be arranged in pixel apertures (OH) defined in the pixel defining layer (PDL) and may be distinguished.

[0107] Each of the first to third light-emitting elements (ED-1, ED-2, ED-3) may include a first electrode (EL1), a second electrode (EL2) facing the first electrode (EL1), a light-emitting layer (EML-B, EML-G, EML-R) disposed between the first electrode (EL1) and the second electrode (EL2), and a functional layer (FL) disposed between the first electrode (EL1) and the second electrode (EL2). The functional layer (FL) may be disposed in at least one of between the first electrode (EL1) and the light-emitting layer (EML-B, EML-G, EML-R) and between the light-emitting layer (EML-B, EML-G, EML-R) and the second electrode (EL2). In one embodiment, each of the first to third light-emitting elements (ED-1, ED-2, ED-3) may include a first electrode (EL1), a first functional layer (FL-B), a light-emitting layer (EML-B, EML-G, EML-R), a second functional layer (FL-T), and a second electrode (EL2) sequentially stacked in the direction of the third direction axis (DR3).

[0108] The first electrode (EL1) may be exposed in the pixel opening (OH) of the pixel defining layer (PDL). The first electrode (EL1) has conductivity. The first electrode (EL1) may be formed of a metal material, a metal alloy, or a conductive compound. The first electrode (EL1) may be an anode or a cathode. However, the embodiment is not limited thereto.

[0109] In addition, the first electrode (EL1) may be a pixel electrode. The first electrode (EL1) may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. The first electrode (EL1) may include at least one selected from Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, W, In, Sn, and Zn, two or more compounds selected from these, a mixture of two or more selected from these, or an oxide thereof.

[0110] When the first electrode (EL1) is a transmissive electrode, the first electrode (EL1) may include a transparent metal oxide, for example, ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), ITZO (indium tin zinc oxide), etc. When the first electrode (EL1) is a semi-transmissive electrode or a reflective electrode, the first electrode (EL1) may include Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca (a laminated structure of LiF and Ca), LiF / Al (a laminated structure of LiF and Al), Mo, Ti, W, or a compound or mixture thereof (for example, a mixture of Ag and Mg). Alternatively, the first electrode (EL1) may have a multi-layer structure including a reflective film or a semi-transparent film formed of the above-described material and a transparent conductive film formed of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), etc. For example, the first electrode (EL1) may have a three-layer structure of ITO / Ag / ITO, but is not limited thereto. In addition, the first electrode (EL1) may include the above-described metal material, a combination of two or more metal materials selected from the above-described metal materials, or an oxide of the above-described metal materials, but the embodiment is not limited thereto. The thickness of the first electrode (EL1) may be about 700 Å to about 10,000 Å. For example, the thickness of the first electrode (EL1) may be about 1,000 Å to about 3,000 Å.

[0111] The second electrode (EL2) may be disposed on the first electrode (EL1). The second electrode (EL2) may be a cathode or an anode. In one embodiment, when the first electrode (EL1) is an anode, the second electrode (EL2) may be a cathode, and when the first electrode (EL1) is a cathode, the second electrode (EL2) may be an anode. The second electrode (EL2) may be a common electrode. However, the embodiment is not limited thereto.

[0112] The second electrode (EL2) may include at least one selected from Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, W, In, Sn, and Zn, two or more compounds selected from these, a mixture of two or more compounds selected from these, or an oxide thereof.

[0113] The second electrode (EL2) may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. When the second electrode (EL2) is a transmissive electrode, the second electrode (EL2) may be made of a transparent metal oxide, for example, ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), ITZO (indium tin zinc oxide), etc.

[0114] When the second electrode (EL2) is a semi-transmissive electrode or a reflective electrode, the second electrode (EL2) may include Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF / Ca, LiF / Al, Mo, Ti, Yb, W, or a compound or mixture containing these (for example, AgMg, AgYb, or MgYb). Alternatively, the second electrode (EL2) may have a multi-layer structure including a reflective film or a semi-transmissive film formed of the above material and a transparent conductive film formed of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), or the like. For example, the second electrode (EL2) may include the above-described metal material, a combination of two or more metal materials selected from the above-described metal materials, or an oxide of the above-described metal materials.

[0115] Although not shown, the second electrode (EL2) may be connected to an auxiliary electrode. When the second electrode (EL2) is connected to the auxiliary electrode, the resistance of the second electrode (EL2) may be reduced.

[0116] A light-emitting layer (EML-B, EML-G, EML-R) may be disposed between a first electrode (EL1) and a second electrode (EL2). The light-emitting element (ED) of one embodiment may include a quantum dot complex (QD-C1, QD-C2, QD-C3) of one embodiment in the light-emitting layer (EML-B, EML-G, EML-R). In addition, the display device (DD) of one embodiment may include first to third light-emitting elements (ED-1, ED-2, ED-3) that are distinct from each other, and at least one of the first to third light-emitting elements (ED-1, ED-2, ED-3) may include a light-emitting layer (EML-B, EML-G, EML-R) including a quantum dot complex (QD-C1, QD-C2, QD-C3) according to one embodiment.

[0117] The quantum dot complex (QD-C1, QD-C2, QD-C3) of one embodiment may include a quantum dot and two different ligands. The quantum dot complex (QD-C1, QD-C2, QD-C3) of one embodiment may include two different ligands, and one of the ligands may include a carboxyl group, which is an acid functional group, at the terminal thereof, thereby exhibiting surface characteristics with improved compatibility with polar materials. Accordingly, the light-emitting element (ED) of one embodiment may exhibit excellent film properties and excellent adhesion to an adjacent functional layer (FL), thereby exhibiting excellent device characteristics and reliability.

[0118] In addition, a display device (DD) of one embodiment including a plurality of light-emitting elements (ED) including quantum dot complexes (QD-C1, QD-C2, QD-C3) according to one embodiment can also exhibit excellent display quality and reliability characteristics due to the improved surface properties of these quantum dot complexes (QD-C1, QD-C2, QD-C3).

[0119] Each of the light-emitting layers (EML-B, EML-G, EML-R) may include a plurality of quantum dot complexes (QD-C1, QD-C2, QD-C3). Meanwhile, in one embodiment, the light-emitting layers (EML-B, EML-G, EML-R) may emit fluorescent light. For example, the quantum dot complexes (QD-C1, QD-C2, QD-C3) may be used as a fluorescent dopant material.

[0120] In one embodiment, the first light-emitting element (ED-1) may include a first light-emitting layer (EML-B) including a first quantum dot complex (QD-C1), the second light-emitting element (ED-2) may include a second light-emitting layer (EML-G) including a second quantum dot complex (QD-C2), and the third light-emitting element (ED-3) may include a third light-emitting layer (EML-R) including a third quantum dot complex (QD-C3). In one embodiment, the first quantum dot complex (QD-C1) may emit blue light, the second quantum dot complex (QD-C2) may emit green light, and the third quantum dot complex (QD-C3) may emit red light. However, the embodiment is not limited thereto, and the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) may emit light in a wavelength range other than blue, green, and red.

[0121] Each of the quantum dot complexes (QD-C1, QD-C2, QD-C3) included in the light-emitting layers (EML-B, EML-G, EML-R) can be stacked to form a layer. In Fig. 4, quantum dot complexes (QD-C1, QD-C2, QD-C3) having a circular cross-section are arranged to roughly form two layers, but the embodiment is not limited thereto. For example, the arrangement of the quantum dot complexes (QD-C1, QD-C2, QD-C3) may vary depending on the thickness of the light-emitting layers (EML-B, EML-G, EML-R), the shape of the quantum dot complexes (QD-C1, QD-C2, QD-C3) included in the light-emitting layers (EML-B, EML-G, EML-R), the average diameter of the quantum dot complexes (QD-C1, QD-C2, QD-C3), etc. Specifically, in the light-emitting layers (EML-B, EML-G, EML-R), the quantum dot complexes (QD-C1, QD-C2, QD-C3) may be aligned adjacent to each other to form one layer, or may be aligned to form multiple layers, such as two or three layers. In addition, the light-emitting layers (EML-B, EML-G, EML-R) may further include a light-emitting material in addition to the quantum dot complexes (QD-C1, QD-C2, QD-C3). In one embodiment, the light-emitting layers (EML-B, EML-G, EML-R) may further include a fluorescent or phosphorescent dopant material, or may further include a host material.

[0122] In one embodiment, the quantum dot complexes (QD-C1, QD-C2, QD-C3) may include a quantum dot and two types of ligands bound to the quantum dot. The quantum dots constituting the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) may be composed of different materials. Alternatively, the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) may be formed of the same quantum dot material, or two quantum dots selected from the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) may be formed of the same material and the rest may be formed of different materials.

[0123] In addition, in one embodiment, the quantum dot complexes (QD-C1, QD-C2, QD-C3) may each include a core and a shell surrounding the core. Accordingly, the quantum dot complexes (QD-C1, QD-C2, QD-C3) may each have a core-shell structure. In one embodiment, the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) included in the light-emitting devices (ED-1, ED-2, ED-3) may be formed of different core materials. In addition, alternatively, the first to third quantum dot complexes (QD-C1, QD-C, QD-C3) may be formed of the same core material, or two quantum dots selected from the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) may be formed of the same core material and the rest may be formed of different core materials.

[0124] In one embodiment, the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) may have different diameters. For example, the first quantum dot complex (QD-C1) used in the first light-emitting device (ED-1) that emits light in a relatively short wavelength range may have a relatively smaller average diameter compared to the second quantum dot complex (QD-C2) of the second light-emitting device (ED-2) that emits light in a relatively long wavelength range and the third quantum dot complex (QD-C3) of the third light-emitting device (ED-3). Meanwhile, in the present specification, the average diameter corresponds to an arithmetic average of the diameters of a plurality of quantum dot particles. Meanwhile, the diameter of a quantum dot particle may be an average value of the width of the quantum dot particle in a cross-section.

[0125] The relationship between the average diameters of the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) is not limited to the above limitations. That is, in FIG. 4, the sizes of the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) are illustrated as being similar to each other, but, unlike what is illustrated, the sizes of the first to third quantum dot complexes (QD-C1, QD-C2, QD-C3) included in the light-emitting elements (ED-1, ED-2, ED-3) may be different.

[0126] The physical and chemical properties, such as the structure and material, of the quantum dot complex (QD-C1, QD-C2, QD-C3) according to one embodiment will be described in more detail below with reference to FIGS. 6 to 7b, etc.

[0127] Meanwhile, in FIG. 4, the thicknesses of the light-emitting layers (EML-B, EML-G, EML-R) of the first to third light-emitting elements (ED-1, ED-2, ED-3) in the display device (DD) of one embodiment are all similar, but the embodiment is not limited thereto. For example, in one embodiment, the thicknesses of the light-emitting layers (EML-B, EML-G, EML-R) of the first to third light-emitting elements (ED-1, ED-2, ED-3) may be different from each other.

[0128] One of the first functional layer (FL-B) disposed between the first electrode (EL1) and the light-emitting layer (EML-B, EML-G, EML-R), and the second functional layer (FL-T) disposed between the light-emitting layer (EML-B, EML-G, EML-R) and the second electrode (EL2) may be a hole transport region, and the other may be an electron transport region.

[0129] FIGS. 5A and 5B are diagrams each showing a light-emitting element according to one embodiment. The structure of the light-emitting elements (ED-a, ED-b) described with reference to FIGS. 5A and 5B can be applied to at least one of the first to third light-emitting elements (ED-1, ED-2, ED-3) illustrated in FIG. 4.

[0130] In FIG. 5a, a light-emitting element (ED-a) of one embodiment may include a first electrode (EL1), a hole transport region (HTR), an emission layer (EML), an electron transport region (ETR), and a second electrode (EL2) sequentially stacked along a third direction axis (DR3). In the light-emitting element (ED-a) of one embodiment, the first electrode (EL1) may be an anode, and the second electrode (EL2) may be a cathode.

[0131] In addition, referring to FIG. 5b, the light-emitting element (ED-b) of one embodiment may include a first electrode (EL1), an electron transport region (ETR), an emission layer (EML), a hole transport region (HTR), and a second electrode (EL2) sequentially stacked along a third direction axis (DR3). In the light-emitting element (ED-b) of one embodiment, the first electrode (EL1) may be a cathode, and the second electrode (EL2) may be an anode.

[0132] That is, the first to third light-emitting elements (ED-1, ED-2, ED-3) shown in FIG. 4 may have the stacked structure of FIG. 5a or FIG. 5b. Accordingly, in the first to third light-emitting elements (ED-1, ED-2, ED-3), when the first functional layer (FL-B) is a hole transport region (HTR), the second functional layer (FL-T) may be an electron transport region (ETR), and in the first to third light-emitting elements (ED-1, ED-2, ED-3), when the first functional layer (FL-B) is an electron transport region (ETR), the second functional layer (FL-T) may be a hole transport region (HTR).

[0133] The light-emitting layers (EML-B, EML-G, EML-R) including the quantum dot complexes (QD-C1, QD-C2, QD-C3) according to one embodiment can exhibit excellent adhesion at the interface with the first functional layer (FL-B) or the second functional layer (FL-T). The quantum dot complexes (QD-C1, QD-C2, QD-C3) according to one embodiment can enable the light-emitting layers (EML-B, EML-G, EML-R) provided on the first functional layer (FL-B) to have excellent film properties, and can also enable the second functional layer (FL-T) provided on the light-emitting layers (EML-B, EML-G, EML-R) to have excellent film properties.

[0134] In the light-emitting devices (ED-a, ED-b) according to one embodiment illustrated in FIGS. 5a and 5b, the hole transport region (HTR) may include a hole injection layer (not shown) and a hole transport layer (not shown). The hole transport region (HTR) may have a multilayer structure having a single layer made of a single material, a single layer made of multiple different materials, or multiple layers made of multiple different materials.

[0135] The hole transport region (HTR) can be formed using various methods such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0136] The hole transport region (HTR) may include a known hole injection material and / or a known hole transport material. For example, the hole transport region (HTR) may include a phthalocyanine compound such as copper phthalocyanine, DNTPD(N 1 ,N 1' -([1,1'-biphenyl]-4,4'-diyl)bis(N 1 -phenyl-N 4 ,N 4-di-m-tolylbenzene-1,4-diamine)), m-MTDATA(4,4',4"-[tris(3-methylphenyl)phenylamino] triphenylamine), TDATA(4,4',4"-Tris(N,N-diphenylamino)triphenylamine), 2-TNATA(4,4',4"-tris[N(2-naphthyl)-N-phenylamino]-triphenylamine), PEDOT / PSS(Poly(3,4-ethylenedioxythiophene) / Poly(4-styrenesulfonate)), PANI / DBSA(Polyaniline / Dodecylbenzenesulfonic acid), PANI / CSA(Polyaniline / Camphor sulfonicacid), PANI / PSS(Polyaniline / Poly(4-styrenesulfonate)), NPB(N,N'-di(naphthalene-l-yl)-N,N'-diphenyl-benzidine), 트리페닐아민을 포함하는 폴리에테르케톤(TPAPEK), 4-Isopropyl-4'-methyldiphenyliodonium [Tetrakis(pentafluorophenyl)borate], HATCN(dipyrazino[2,3-f: 2',3'-h] quinoxaline-2,3,6,7,10,11-hexacarbonitrile) 등을 포함할 수 있다.

[0137] In addition, the hole transport region (HTR) is formed by carbazole derivatives such as N-phenylcarbazole and polyvinylcarbazole, fluorene derivatives, triphenylamine derivatives such as TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine), TCTA (4,4',4"-tris(N-carbazolyl)triphenylamine), NPB (N,N'-di(naphthalene-l-yl)-N,N'-diplienyl-benzidine), TAPC (4,4′-Cyclohexylidene bis[N,N-bis(4-methylphenyl)benzenamine]), HMTPD (4,4'-Bis[N,N'-(3-tolyl)amino]-3,3'-dimethylbiphenyl), CzSi(9-(4-tert-Butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole), CCP(9-phenyl-9H-3,9'-bicarbazole), mCP(1,3-Bis(N-carbazolyl)benzene), or It may include mDCP (1,3-bis(1,8-dimethyl-9H-carbazol-9-yl)benzene).

[0138] The thickness of the hole transport region (HTR) may be from about 5 nm to about 1,500 nm, for example, from about 10 nm to about 500 nm. When the thickness of the hole transport region (HTR) satisfies the range described above, satisfactory hole transport characteristics can be obtained without a substantial increase in driving voltage.

[0139] In a light-emitting device (ED-a, ED-b) according to one embodiment, the electron transport region (ETR) may include at least one of an electron transport layer (not shown) and an electron injection layer (not shown), but the embodiment is not limited thereto.

[0140] The electron transport region (ETR) may have a single layer composed of a single material, a single layer composed of multiple different materials, or a multilayer structure having multiple layers composed of multiple different materials. For example, the electron transport region (ETR) may have a single layer structure of an electron injection layer or an electron transport layer, or a single layer structure composed of an electron injection material and an electron transport material. The thickness of the electron transport region (ETR) may be, for example, about 20 nm to about 150 nm.

[0141] The electron transport region (ETR) can be formed using various methods such as vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) method, inkjet printing, laser printing, and laser induced thermal imaging (LITI).

[0142] The electron transport region (ETR) may include a known electron injecting material and / or a known electron transport material. For example, the electron transport region (ETR) may include an anthracene-based compound. Alternatively, the electron transport region (ETR) is, for example, Alq3 (Tris(8-hydroxyquinolinato)aluminum), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, 2-(4-(N-phenylbenzoimidazol-1-yl)phenyl)-9,10-dinaphthylanthracene, TPBi(1,3,5-Tri(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene), BCP(2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphen (4,7-Diphenyl-1,10-phenanthroline), It may include TAZ(3-(4-Biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole), NTAZ(4-(Naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole), tBu-PBD(2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), BAlq(Bis(2-methyl-8-quinolinolato-N1,O8)-(1,1'-Biphenyl-4-olato)aluminum), Bebq2(berylliumbis(benzoquinolin-10-olate)), ADN(9,10-di(naphthalene-2-yl)anthracene), BmPyPhB(1,3-Bis[3,5-di(pyridin-3-yl)phenyl]benzene) and mixtures thereof.Alternatively, the electron transport domain (ETR) may include BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), TSPO1 (diphenyl(4-(triphenylsilyl)phenyl)phosphine oxide), Bphen (4,7-diphenyl-1,10-phenanthroline), etc.

[0143] Referring to FIG. 4, the first functional layer (FL-B) and the second functional layer (FL-T) may be provided as a common layer throughout the light-emitting regions (PXA-B, PXA-G, PXA-R). In one embodiment, the functional layer (FL) may overlap both the light-emitting layers (EML-B, EML-G, EML-R) and the pixel defining layer (PDL). However, the embodiment is not limited thereto, and at least one of the first functional layer (FL-B) and the second functional layer (FL-T) may be provided by being patterned to overlap the light-emitting layers (EML-B, EML-G, EML-R) and be disposed within the pixel opening (OH).

[0144] Referring to FIG. 4, a display device (DD) of one embodiment includes an optical structure layer (PP) disposed on a display panel (DP). The optical structure layer (PP) may include a base layer (BL) and a color filter layer (CFL).

[0145] The base layer (BL) may be a member that provides a base surface on which a color filter layer (CFL) or the like is placed. The base layer (BL) may be a glass substrate, a metal substrate, a plastic substrate, or the like. However, the embodiment is not limited thereto, and the base layer (BL) may be an inorganic layer, an organic layer, or a composite material layer.

[0146] The color filter layer (CFL) may include filters (CF-B, CF-G, CF-R). The color filter layer (CFL) may include first to third filters (CF-B, CF-G, CF-R). Each of the first to third filters (CF-B, CF-G, CF-R) may be arranged to correspond to the first to third light-emitting elements (ED-1, ED-2, ED-3). For example, the first filter (CF-B) may be a blue filter, the second filter (CF-G) may be a green filter, and the third filter (CF-R) may be a red filter. Each of the first to third filters (CF-B, CF-G, CF-R) may be arranged to correspond to the first to third pixel areas (PXA-B, PXA-G, PXA-R).

[0147] In addition, a plurality of filters (CF-B, CF-G, CF-R) that transmit different light can be overlapped and arranged in response to the peripheral region (NPXA) arranged between the light-emitting regions (PXA-R, PXA-B, PXA-G). The plurality of filters (CF-B, CF-G, CF-R) can be overlapped and arranged in the third direction (DR3), which is the thickness direction, to distinguish the boundary between adjacent light-emitting regions (PXA-R, PXA-B, PXA-G). Accordingly, the light-blocking effect of external light increases, and a function such as a black matrix can be achieved. The overlapping structure of the plurality of filters (CF-B, CF-G, CF-R) can have a function of preventing color mixing.

[0148] Each of the first to third filters (CF-B, CF-G, CF-R) may include a polymer photosensitive resin and a pigment or dye. The first filter (CF-B) may include a blue pigment or a blue dye, the second filter (CF-G) may include a green pigment or a green dye, and the third filter (CF-R) may include a red pigment or a red dye. However, the embodiment is not limited thereto, and the first filter (CF-B) may not include a pigment or a dye. The first filter (CF-B) may include a polymer photosensitive resin and not include a pigment or a dye. The first filter (CF-B) may be transparent. The first filter (CF-B) may be formed of a transparent photosensitive resin.

[0149] The color filter layer (CFL) may further include a buffer layer (BFL). For example, the buffer layer (BFL) may be a protective layer that protects the first to third filters (CF-B, CF-G, CF-R). The buffer layer (BFL) may be an inorganic layer containing at least one inorganic material selected from the group consisting of silicon nitride, silicon oxide, and silicon oxynitride. The buffer layer (BFL) may be formed of a single layer or multiple layers.

[0150] Additionally, the second filter (CF-G) and the third filter (CF-R) may be yellow filters. The second filter (CF-G) and the third filter (CF-R) may be provided as a single unit without being distinguished from each other.

[0151] Although not shown, the color filter layer (CFL) may further include a shading portion (not shown). The shading portion may be a black matrix. The shading portion may be formed by including an organic shading material or an inorganic shading material including a black pigment or a black dye. The shading portion may prevent light leakage and demarcate boundaries between adjacent filters (CF-B, CF-G, CF-R).

[0152] In addition, unlike those illustrated in FIG. 4, the optical structure layer (PP) of the display device (DD) of one embodiment may not include a color filter layer (CFL).

[0153] The light-emitting layer of the light-emitting element (ED, ED-a, ED-b) according to one embodiment described with reference to FIGS. 4 to 5b may include a quantum dot complex according to one embodiment.

[0154] Fig. 6 is a schematic diagram of a quantum dot complex according to one embodiment. Figs. 7a and 7b are schematic diagrams each showing an enlarged portion of a quantum dot complex. Fig. 7a is an enlarged view of the XX' region of Fig. 6, and Fig. 7b is an enlarged view of the YY' region of Fig. 6.

[0155] Referring to FIG. 6, a quantum dot complex of one embodiment may include a quantum dot (MC), a first ligand (LD-C) and a second ligand (LD-M) bound to the surface of the quantum dot. The first ligand (LD-C) and the second ligand (LD-M) may be different from each other.

[0156] Quantum dots (MC) are crystals of a semiconductor compound, and may contain any material capable of emitting light of various wavelengths depending on the size of the crystal or by controlling the element ratio within the quantum dot (MC) compound. Quantum dots (MC) may include semiconductor nanocrystals.

[0157] Quantum dots (MC) can be synthesized by wet chemical processes, metalorganic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or similar processes. The wet chemical process involves mixing an organic solvent with a precursor material and then growing MC crystals. As the crystals grow, the organic solvent naturally acts as a dispersant coordinated to the MC crystal surface, controlling crystal growth. Therefore, the wet chemical process is easier and less expensive than vapor deposition methods such as metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE), allowing for controlled growth of MC particles.

[0158] Quantum dots (MC) can be selected from group II-VI compounds, group III-VI compounds, group I-III-VI compounds, group III-V compounds, group III-II-V compounds, group I IV-VI compounds, group IV elements, group IV compounds, and combinations thereof.

[0159] The group II-VI compound is a binary compound selected from the group consisting of CdSe, CdTe, CdS, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS and mixtures thereof; a ternary compound selected from the group consisting of CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS and mixtures thereof; Or it may include a four-element compound selected from the group consisting of HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and mixtures thereof.

[0160] The III-VI group compounds may include binary compounds such as In2S3, In2Se3, etc., ternary compounds such as InGaS3, InGaSe3, etc., or any combination thereof.

[0161] Group I-III-VI compounds are ternary compounds selected from the group consisting of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2CuGaO2, AgGaO2, AgAlO2 and mixtures thereof, or AgInGaS2, It may include four-element compounds such as CuInGaS2.

[0162] The Group III-V compound may include a binary compound selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; a ternary compound selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InGaP, InAlP, InNP, InNAs, InNSb, InPAs, InPSb, and mixtures thereof; or a quaternary compound selected from the group consisting of GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof. Meanwhile, the Group III-V compound may further include a Group II metal. For example, InZnP, etc. can be selected as a III-II-V group compound.

[0163] The Group IV-VI compound may include a binary compound selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; a ternary compound selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; or a quaternary compound selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and mixtures thereof. The Group IV element may be selected from the group consisting of Si, Ge, and mixtures thereof. The Group IV compound may be a binary compound selected from the group consisting of SiC, SiGe, and mixtures thereof.

[0164] At this time, the binary, ternary, or quaternary compound may exist within the particle at a uniform concentration, or may exist within the same particle with a partially different concentration distribution. In addition, in one embodiment, the quantum dot (MC) may have a core-shell structure including a core (CR) and a shell (SL). In the core-shell structure, the concentration of the element present in the shell (SL) may have a concentration gradient in which it decreases as it goes toward the core (CR).

[0165] A quantum dot (MC) according to one embodiment having a core-shell structure may include a core (CR) including the aforementioned nanocrystals and a shell (SL) surrounding the core and including the nanocrystals. The shell (SL) of the quantum dot may function as a protective layer to maintain semiconductor properties by preventing chemical modification of the core (CR) and / or as a charging layer to impart electrophoretic properties to the quantum dot. The shell (SL) may be a single layer or a multilayer. Examples of the shell (SL) of the quantum dot include an oxide of a metal or a non-metal, a semiconductor compound, or a combination thereof.

[0166] The shell (SL) may comprise a different material from the core (CR). For example, the core (CR) may comprise a first semiconductor nanocrystal, and the shell (SL) may comprise a second semiconductor nanocrystal that is different from the first semiconductor nanocrystal. Alternatively, the shell (SL) may comprise an oxide of a metal or a non-metal. The shell (SL) may comprise an oxide of a metal or a non-metal, a semiconductor nanocrystal, or a combination thereof.

[0167] The shell (SL) may be formed of a single material, but may also be formed to have a concentration gradient. For example, the shell (SL) may have a concentration gradient such that the concentration of the second semiconductor nanocrystals present in the shell (SL) decreases as it approaches the core (CR), and the concentration of the first semiconductor nanocrystals included in the core (CR) increases. Meanwhile, although FIG. 5A illustrates that the shell (SL) has a single-layer structure, the present invention is not limited thereto, and the shell (SL) may have a multiple-layer structure including different materials.

[0168] For example, the oxide of the metal or non-metal may be a binary compound such as SiO2, Al2O3, TiO2, ZnO, MnO, Mn2O3, Mn3O4, CuO, FeO, Fe2O3, Fe3O4, CoO, Co3O4, NiO, or a ternary compound such as MgAl2O4, CoFe2O4, NiFe2O4, CoMn2O4, but the present invention is not limited thereto.

[0169] In addition, the semiconductor compound may be exemplified by CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnSeS, ZnTeS, GaAs, GaP, GaSb, HgS, HgSe, HgTe, InAs, InP, InGaP, InSb, AlAs, AlP, AlSb, etc., but the present invention is not limited thereto.

[0170] Quantum dots (MCs) can have a full width of half maximum (FWHM) of the emission wavelength spectrum of approximately 45 nm or less, potentially enhancing color purity and color reproducibility within this range. Furthermore, light emitted from these quantum dots is emitted in all directions, potentially enhancing the viewing angle.

[0171] In addition, the shape of the quantum dot (MC) is not particularly limited to a shape commonly used in the field, but more specifically, a shape such as a spherical, pyramidal, multi-arm, or cubic nanoparticle, nanotube, nanowire, nanofiber, or nanoplatelet particle can be used.

[0172] Since the energy band gap of quantum dots (MC) can be controlled by controlling the size or the element ratio within the quantum dot (MC) compound, light of various wavelengths can be emitted from an emission layer (EML, FIGS. 5a and 5b) including a quantum dot complex (QD-C) formed by including quantum dots (MC). Therefore, by using quantum dots (MC) of different sizes as described above or by using quantum dot complexes (QD-C) having different element ratios within the quantum dot (MC) compound, a light-emitting device that emits light of various wavelengths can be implemented. Specifically, by controlling the size of the quantum dot (MC) or the element ratio within the quantum dot (MC) compound, the quantum dot complex (QD-C) can have various emission colors such as blue, red, and green. In addition, the quantum dot complexes (QD-C) can be configured to emit white light by combining light of various colors. The smaller the particle size of the quantum dot (MC), the more the quantum dot complex (QD-C) can emit light in the short-wavelength region. For example, in quantum dots (MC) having the same core, the particle size of a quantum dot that emits green light may be smaller than the particle size of a quantum dot that emits red light. Furthermore, in quantum dots (MC) having the same core, the particle size of a quantum dot that emits blue light may be smaller than the particle size of a quantum dot that emits green light. However, the embodiment is not limited thereto, and even in quantum dots (MC) having the same core, the particle size may be controlled depending on the shell forming material and shell thickness, etc.

[0173] Meanwhile, when the quantum dot complex (QD-C) has various emission colors such as blue, red, and green, the quantum dots (MC) having different emission colors may have different materials for the cores (CR).

[0174] In one embodiment, the core (CR) may include a group III-V compound or a group I-III-VI compound. For example, the core (CR) may include InP or AgInGaS. The quantum dot (MC) of one embodiment may have a relatively high blue light absorbance by including a core (CR) including a group III-V compound or a group I-III-VI compound.

[0175] In one embodiment, the quantum dot (MC) may be a non-cadmium (Cd) quantum dot. That is, the quantum dot (MC) may not contain cadmium (Cd). The quantum dot (MC) may contain two or more elements selected from elements of Group II and Group VI, excluding Cd. The quantum dot (MC) may be formed by including two, three, or four elements selected from elements of Group II and Group VI, excluding Cd. For example, in one embodiment, the quantum dot (MC) may contain ZnSeTe.

[0176] In one embodiment, the quantum dot complex (QD-C) can absorb light in a wavelength range of 300 nm to 500 nm. For example, in one embodiment, the quantum dot complex (QD-C) can absorb light in a wavelength range of 300 nm to 450 nm. The quantum dot complex (QD-C) can absorb light in the wavelength range described above and emit blue light, green light, or red light.

[0177] In one embodiment, the diameter of the quantum dot (MC) may be 1 nm or more and 10 nm or less. When the quantum dot (MC) satisfies the average particle diameter range described above, it can exhibit not only characteristic behavior as a quantum dot (MC) but also have excellent dispersibility. In addition, by selecting various average particle diameters of the quantum dot (MC) within the above-described range, the emission wavelength of the quantum dot (MC) and / or the semiconductor properties of the quantum dot can be varied.

[0178] In one embodiment, a quantum dot complex (QD-C) may include a quantum dot (MC), a first ligand (LD-C) bound to a surface of the quantum dot (MC), and a second ligand (LD-M) bound to the surface of the quantum dot (MC) and different from the first ligand (LD-C). In one embodiment, the quantum dot complex (QD-C) may include the second ligand (LD-M) having two different functional groups, thereby exhibiting modified surface properties compared to a case in which the quantum dot complex (QD-C) only includes the first ligand (LD-C). In one embodiment, the quantum dot (MC) includes a core (CR) and a shell (SL), and the first ligand (LD-C) and the second ligand (LD-M) may be bound to the surface of the shell (SL).

[0179] Referring to FIGS. 6 and 7a, the first ligand (LD-C) may include a thiol group at one end adjacent to the surface of the quantum dot (MC). The first ligand (LD-C) may include a first head portion (HP1) bonded to the surface of the quantum dot (MC) and a first tail portion (TP1) extending from the first head portion (HP1). The first head portion (HP1) may be a portion including a thiol group, and the first tail portion (TP1) may be a portion including an alkyl group. The first tail portion (TP1) may be a portion corresponding to a substituted or unsubstituted alkyl group. The first tail portion (TP1) may include an alkyl group having 2 to 20 carbon atoms.

[0180] Referring to FIGS. 6 and 7b, the second ligand (LD-M) may include a thiol group at one end adjacent to the quantum dot (MC) surface and a carboxyl group at the other end spaced from the quantum dot (MC) surface. The second ligand (LD-M) may include a plurality of functional groups having different polarities. The second ligand (LD-M) may include two different functional groups. The second ligand may be an amphiphilic substance.

[0181] The second ligand (LD-M) may include a second head portion (HP2) bonded to the surface of the quantum dot (MC), a terminal portion (EP) spaced from the surface of the quantum dot (MC), and a second tail portion (TP2) disposed between the second head portion (HP2) and the terminal portion (EP). The second head portion (HP2) may be a portion including a thiol group, and the second tail portion (TP2) may be a portion including an alkyl group. The second tail portion (TP2) may be a portion corresponding to a substituted or unsubstituted alkyl group. The second tail portion (TP2) may include a substituted or unsubstituted alkyl group having 2 to 20 carbon atoms. The terminal portion (EP) may be a portion including a carboxyl group. The terminal portion (EP) is exposed to the outside of the quantum dot complex (QD-C) and may control the surface properties of the quantum dot complex (QD-C). A quantum dot complex (QD-C) comprising a second ligand (LD-M) having an acidic group such as a carboxyl group can have increased polarity on the surface.

[0182] The first ligand (LD-C) and the second ligand (LD-M) may each be a monodentate ligand having a corresponding head portion (HP1, HP2) that includes a single functional group for binding to the surface of a quantum dot (MC). That is, the first head portion (HP1) and the second head portion (HP2) may each include single functional groups for binding to the surface of a quantum dot (MC). However, the present invention is not limited thereto, and the first ligand (LD-C) and the second ligand (LD-M) may each be a bidentate ligand having a corresponding head portion (HP1, HP2) that includes two functional groups for binding to the surface of a quantum dot (MC). The head portions (HP1, HP2) include functional groups for binding to the surface of a quantum dot (MC), and thus the ligands (LD-C, LD-M) can be effectively bound to the quantum dot (MC). In one embodiment, the first head portion (HP1) and the second head portion (HP2) may include a thiol group.

[0183] Each of the first ligand (LD-C) and the second ligand (LD-M) includes a tail portion (TP1, TP2), and one end of the tail portion (TP1, TP2) may be connected to the head portion (HP1, HP2). Meanwhile, in one embodiment, one end of the first tail portion (TP1) of the first ligand (LD-C) may be connected to the first head portion (HP1) and the other end may be exposed to the outside of the quantum dot complex (QD-C). Furthermore, in one embodiment, one end of the second tail portion (TP2) of the second ligand (LD-M) may be connected to the second head portion (HP2) and the other end may be connected to an end portion (EP) exposed to the outside of the quantum dot complex (QD-C).

[0184] In one embodiment, the second ligand (LD-M) may be represented by the following chemical formula 1.

[0185] [Chemical Formula 1]

[0186]

[0187] In chemical formula 1, n is an integer of 1 to 20, and R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

[0188] The second ligand (LD-M) may be represented by any one of the following compounds LD1 to LD4. The quantum dot complex (QD-C) according to one embodiment may include at least one of the following compounds LD1 to LD4 as the second ligand (LD-M).

[0189]

[0190] LD1 can be named as MPA (3-mercaptopropanoic acid), LD2 as DHLA (Dihydrolipoic acid), LD3 as CYS (Cysteine), and LD4 as TGA (Thioglycolic acid), respectively.

[0191] That is, LD1 to LD4 may each contain a thiol group at one end and a carboxyl group at the other end.

[0192] In a quantum dot complex (QD-C) according to one embodiment, the first ligand (LD-C) and the second ligand (LD-M) may each be bound to the surface of the quantum dot (MC). In a quantum dot complex (QD-C) according to one embodiment, the first ligand (LD-C) may be included in a greater weight ratio than the second ligand (LD-M). In a quantum dot complex (QD-C) according to one embodiment, the weight ratio of the first ligand (LD-C) and the second ligand (LD-M) may be 99:1 to 50:50. For example, in a quantum dot complex (QD-C), the weight ratio of the first ligand (LD-C) and the second ligand (LD-M) may be 99:1 to 90:10. Specifically, the weight ratio of the first ligand (LD-C) and the second ligand (LD-M) in the quantum dot complex (QD-C) may be 98:2 to 90:10.

[0193] In one embodiment, the quantum dot complex (QD-C) may have modified surface properties by including at least 1 second ligand (LD-M) relative to 100 weight percent of the total ligands. In addition, the quantum dot complex (QD-C) may have excellent surface modification properties by including at most 50 weight percent of the second ligand (LD-M) relative to 100 weight percent of the total ligands, while maintaining good optical properties and compatibility with non-polar materials. For example, the quantum dot complex (QD-C) may have at least 2 and at most 10 weight percent of the second ligand (LD-M) relative to 100 weight percent of the total ligands, and may exhibit excellent surface modification properties, good optical properties, and compatibility with non-polar materials even when the second ligand weight ratio is low.

[0194] In the second ligand (LD-M) according to one embodiment, the thiol group may be a portion adjacent to the quantum dot (MC), and the carboxyl group may be a portion spaced from the quantum dot (MC). Due to the carboxyl group, the quantum dot complex (QD-C) may exhibit polar surface properties. Accordingly, the quantum dot complex (QD-C) has relatively high compatibility with polar solvents such as alcohols or ethers, and the layer including the quantum dot complex (QD-C) and the layers adjacent thereto may exhibit excellent coating properties, respectively. Accordingly, the interface properties between the layer formed including the quantum dot complex (QD-C) and the adjacent functional layer (FL, FIG. 4) are improved.

[0195] For example, the light-emitting device (ED-a) of one embodiment illustrated in FIG. 5a described above may include a quantum dot complex (QD-C) in the light-emitting layer (EML). After forming the light-emitting layer (EML) including the quantum dot complex (QD-C) of one embodiment, an electron transport region (ETR, FIG. 5a) may be provided. When manufacturing the light-emitting device (ED-a) according to one embodiment, the electron transport region (ETR) may be formed directly on the light-emitting layer (EML). The electron transport region (ETR) may be formed from a common layer composition including an electron transport material and an organic solvent. The common layer composition is provided on the light-emitting layer (EML), and the common layer composition may have excellent wetting properties with respect to the light-emitting layer (EML) due to the polar characteristics of the surface of the quantum dot complex (QD-C). The contact angle of the organic solvent with respect to the light-emitting layer (EML) including the quantum dot complex (QD-C) may be 15 degrees or less. For example, the common layer composition may include organic solvents such as DGtBE and TPGBE. However, the type of organic solvent is not limited thereto. The solvents DGtBE and TPGBE are as follows.

[0196]

[0197] In one embodiment, a quantum dot complex (QD-C) can have increased compatibility with an organic solvent of a common layer composition by including a second ligand (LD-M) having a carboxyl group at the terminal end (EP). Since the contact angle of the organic solvent is low, such as 15 degrees or less, the wetting property of a functional layer (FL) formed from the common layer composition and adhesion to an emission layer (EML) can be excellent.

[0198] Accordingly, the interface between the light-emitting layer (EML) and the electron transport region (ETR) has excellent adhesion, and the light-emitting element (ED-b) can exhibit improved reliability due to excellent film properties.

[0199] Meanwhile, the interface characteristics between the electron transport region (ETR) and the light emitting layer (EML) are illustratively described, and other functional layers adjacent to the layer including the quantum dot complex (QD-C) can also exhibit excellent coating properties and excellent interface characteristics due to the modified surface characteristics of the quantum dot complex (QD-C). Accordingly, the light emitting device (ED-a, ED-b, FIGS. 5a, 5b) of one embodiment can exhibit improved reliability due to the excellent adhesion between the layer including the quantum dot complex (QD-C) of one embodiment and the layers adjacent thereto.

[0200] In addition, the quantum dot complex (QD-C) of one embodiment has high compatibility with a polar solvent due to the modified polar surface properties, and thus can be used by being mixed with a polar solvent. A mixture of a polar solvent and a quantum dot complex (QD-C) can be a printing composition. The quantum dot complex (QD-C) can be mixed with a solvent and applied by an inkjet printing process. The quantum dot complex (QD-C) of one embodiment can be applied well through a nozzle of an inkjet printing device without being separated from the solvent. When the quantum dot complex of one embodiment is provided by an inkjet printing process, the light-emitting layer exhibits excellent thin film properties, and the processability of the light-emitting layer manufacturing process can be improved.

[0201] Table 1 below shows the contact angle characteristics of organic solvents for coating layers containing quantum dot complexes of comparative examples and examples. The contact angles evaluated in Table 1 are the contact angles measured when an organic solvent containing DGtBE and TPGBE mixed in a weight ratio of 7:3, which was used as a solvent in the common layer composition forming the functional layer, was applied on a layer formed with a quantum dot complex. In other words, the contact angles in Table 1 correspond to the contact angles of organic solvents for the layer formed with the quantum dot complex.

[0202] The comparative examples evaluated in Table 1 are those in which only the first ligand is bound to the quantum dot surface, and Examples 1 to 4 are those in which the first ligand and the second ligand are bound to the quantum dot surface at the indicated weight ratios, respectively. The first ligand used in the comparative examples and examples is DDT (Dodecanethiol), and the second ligand used in the examples corresponds to MPA (3-mercaptopropanoic acid), which is LD1.

[0203] Weight ratio (1st ligand: 2nd ligand) Contact angle (°) Comparative example 100:022.4 Example 199:114.8 Example 298:210.8 Example 395:59.1 Example 490:1010.9

[0204] Referring to the results in Table 1, it can be seen that the contact angle of the organic solvent in the examples is significantly lower than in the comparative examples. Compared to the comparative examples, which are layers formed of quantum dot complexes in which only the first ligand is bound and no second ligand is not included, it can be confirmed that the contact angle of the organic solvent is reduced by 6 degrees (°) or more in the examples in which the weight ratio of the second ligand among the total ligand weight (100) is 1 or more. That is, in the case of a quantum dot complex including a second ligand having a multifunctional group, since one of the multifunctional groups has polarity, it can be said that the compatibility with the organic solvent is increased compared to the case in which only the first ligand is included. As the weight ratio of the second ligand among the total ligand weight increases, the contact angle of the organic solvent for the layer formed of the quantum dot complex may decrease. On the other hand, when the weight ratio of the second ligand among the total ligand weight increases above a certain level, the degree of decrease in the contact angle of the organic solvent for the layer formed of the quantum dot complex may decrease, or the contact angle of the organic solvent may be maintained within a certain range. For example, referring to Table 1, when the weight ratio of the second ligand among the total ligand weight increases from 5 to 10, it can be said that the change in the contact angle of the organic solvent is not large and is maintained within a similar range.

[0205] When a common layer composition including an organic solvent is provided on a layer formed by including a quantum dot complex in which both the first ligand and the second ligand are bound, as in the examples, the wetting properties of the common layer composition are increased. Accordingly, the common layer composition can be uniformly applied on the layer including the quantum dot complex, and the interface properties between the layer including the quantum dot complex and the adjacent functional layer can be improved.

[0206] Table 2 below shows the luminescence characteristics for quantum dot complexes. Table 2 shows the wavelength (λ) that shows the maximum luminescence at the luminescence peak in comparative examples and examples. PL,max), and the full width at half maximum (FWHM) of the emission peak were evaluated and displayed.

[0207] The composition of the quantum dot complex used in the comparative examples and examples is the same as that of the comparative examples and examples used in the contact angle evaluation described in Table 1. That is, the comparative examples are for quantum dot complexes in which only the first ligand is bound to the quantum dot surface, and examples 1 to 4 are for quantum dot complexes in which the first ligand and the second ligand are bound to the quantum dot surface at the indicated weight ratios, respectively. The first ligand used in the comparative examples and examples is DDT (Dodecanethiol), and the second ligand used in the examples corresponds to MPA (3-mercaptopropanoic acid), which is LD1.

[0208] Meanwhile, Table 2 evaluates the solution state and film state separately. The solution state corresponds to the case where the quantum dot complex is provided in a liquid state, and the film state corresponds to the case where the quantum dot complex is provided to form a single layer in a fixed state.

[0209] Weight ratio (1st ligand: 2nd ligand) Solution state Film state λ PL,max (nm)FWHM(nm)λ PL,max (nm)FWHM(nm)Comparative Example 100:04454044741Example 199:14453844939Example 298:24463945039Example 395:54474046138Example 490:104433844740

[0210] Referring to the results in Table 2, the wavelength (λ) that shows the maximum luminescence at the luminescence peak PL,max) and the full width at half maximum (FWHM) of the emission peak showed similar values ​​for the comparative examples and the examples in the solution state and the film state, respectively. That is, it can be said that the examples show emission characteristics similar to those of the comparative examples in the solution state and the film state, respectively. That is, even when the second ligand is introduced, it can be said that the emission characteristics of the quantum dot complex are maintained at a level similar to that of a conventional quantum dot complex to which a polar functional group is not introduced. In addition, a quantum dot complex according to an embodiment can show optical characteristics similar to that of a conventional quantum dot complex. FIGS. 8A and 8B are drawings showing the results of evaluating the emission characteristics of the comparative examples and the examples, respectively. FIG. 8A shows the absorbance and normalized PL peak of the comparative example and examples 1 to 4 in the solution state. In addition, FIG. 8B shows the normalized emission peak of the comparative example and examples 1 to 4 in the film state. Comparative examples and examples 1 to 4 shown in FIG. 8a correspond to the solution states of the comparative examples and examples 1 to 4 in Table 2 described above, respectively, and comparative examples and examples 1 to 4 shown in FIG. 8b correspond to the film states of the comparative examples and examples 1 to 4 in Table 2 described above, respectively. Referring to FIG. 8a, comparative examples and examples 1 to 4 exhibit similar absorbance and emission peak characteristics. Comparative examples and examples 1 to 4 exhibited absorbance characteristics that absorbed light of 300 nm or more and 450 nm or less. That is, it can be said that examples including a quantum dot complex according to one embodiment including both the first ligand and the second ligand exhibit similar optical characteristics to the comparative example including only the first ligand. In addition, it can be confirmed that the absorbance remains similar even when the second ligand ratio increases, and accordingly, it can be seen that the second ligand, which is an amphiphilic ligand, improves the surface properties of the quantum dot complex while minimizing the influence on the optical properties of the quantum dot complex.

[0211] In addition, it can be confirmed that the luminescence characteristics of the comparative examples and examples are similar in the normalized luminescence peaks shown in Fig. 8a. The shapes of the luminescence peaks and the maximum luminescence wavelengths of the comparative examples and examples also appeared similar. In addition, it can be confirmed that the luminescence peak characteristics are maintained similarly even when the ratio of the second ligand increases. Therefore, considering Table 2 and Fig. 8a described above, it can be seen that the quantum dot complex according to one embodiment exhibits good optical and luminescence characteristics in a solution state.

[0212] Referring to Fig. 8b, it can be seen that the comparative examples and examples 1 to 4 exhibit similar emission peak characteristics even in a film state. That is, the shapes of the emission peaks of the comparative examples and examples were similar even in a film state. Although there are some differences between the comparative examples and examples in terms of maximum emission wavelength, the difference in maximum emission wavelength is within 15 nm, so it can be said that the comparative examples and examples maintain similar emission characteristics. In addition, it can be confirmed that the emission peak characteristics of the examples are similarly maintained even when the ratio of the second ligand increases. Therefore, considering Table 2 and Fig. 8b described above, it can be seen that the quantum dot complex according to one example exhibits good optical and emission characteristics even in a film state.

[0213] Considering Table 2, FIGS. 8A and 8B, it can be confirmed that the optical properties and luminescence properties of the quantum dot complex are maintained at similar levels depending on the presence or absence of the second ligand or the content of the second ligand. That is, in the case of the embodiment additionally including the second ligand, similar optical properties and luminescence properties are exhibited as compared to the comparative example, and accordingly, it can be expected that the optical properties and luminescence wavelength properties of the light-emitting device according to one embodiment will also be maintained at a good level depending on the introduction of the second ligand. In addition, it can be expected that the display device according to one embodiment including the quantum dot complex according to one embodiment will also maintain an excellent display quality level in terms of optical properties and luminescence wavelength properties.

[0214] A quantum dot composite according to one embodiment may have improved surface properties by including both a first ligand having an alkyl group and a second ligand having a carboxyl group at one end spaced from the quantum dot surface. Accordingly, the quantum dot composite may exhibit improved wetting properties with an adjacent coating layer in which a polar solvent or the like is used, thereby exhibiting excellent adhesion at the interface with the adjacent layer. That is, the quantum dot composite according to one embodiment may exhibit excellent interfacial properties and thus excellent reliability by having high wetting properties with an adjacent material while maintaining good optical and luminescent properties. In addition, the quantum dot composite according to one embodiment has improved surface properties, thereby improving compatibility with polar solvents or the like, and may be easily used in an inkjet printing process by being mixed with the solvent. Accordingly, the quantum dot composite according to one embodiment may exhibit excellent applicability when applied to an inkjet printing process.

[0215] A light-emitting device according to one embodiment can exhibit improved device quality by including a quantum dot complex including both a first ligand having an alkyl group and a second ligand having a carboxyl group at one end spaced from the quantum dot surface in a light-emitting layer, thereby maintaining good optical and light-emitting characteristics while having excellent adhesion to an adjacently provided functional layer. In addition, a display device according to one embodiment can exhibit excellent display quality and improved reliability characteristics by including a light-emitting device including a quantum dot complex including both a first ligand having an alkyl group and a second ligand having a carboxyl group at one end spaced from the quantum dot surface in a display layer.

[0216] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes to the present invention can be made without departing from the spirit and technical scope of the present invention as set forth in the claims to be described below.

[0217] Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0218] To maintain the superior luminescence quality of light-emitting devices, research is being conducted on the materials of the light-emitting layer and the lamination characteristics with adjacent functional layers. Therefore, inventions relating to quantum dot composites with excellent quantum yield characteristics and improved interfacial properties with adjacent layers, as well as light-emitting devices comprising such composites, have high industrial applicability.

Claims

1. Quantum dot; A first ligand that binds to the surface of the quantum dot and includes a thiol group at one end; and A quantum dot complex comprising a second ligand, which is different from the first ligand and binds to the surface of the quantum dot and includes a thiol group at one end and a carboxyl group at the other end.

2. In paragraph 1, A quantum dot complex wherein the first ligand comprises a first head portion comprising a thiol group and a first tail portion extending from the first head portion and comprising an alkyl group.

3. In paragraph 2, A quantum dot complex wherein the first tail portion includes an alkyl group having 2 to 20 carbon atoms.

4. In paragraph 1, A quantum dot complex comprising a second head portion comprising a thiol group, a terminal portion spaced from the surface of the quantum dot and comprising a carboxyl group, and a second tail portion disposed between the second head portion and the terminal portion.

5. In paragraph 1, The second ligand is a quantum dot complex represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, n is an integer greater than or equal to 1 and less than or equal to 20, R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

6. In paragraph 1, The second ligand is a quantum dot complex comprising at least one of the following compounds LD1 to LD4: .

7. In paragraph 1, A quantum dot complex wherein the weight ratio of the first ligand and the second ligand is 99:1 to 50:

50.

8. In paragraph 1, The quantum dot comprises a core and a shell surrounding the core, A quantum dot complex wherein each of the first ligand and the second ligand binds to the surface of the shell.

9. In paragraph 8, The core comprises a first semiconductor nanocrystal, and the shell comprises a second semiconductor nanocrystal different from the first semiconductor nanocrystal. A quantum dot complex wherein each of the first semiconductor nanocrystal and the second semiconductor nanocrystal comprises at least one of a group II-VI compound, a group III-VI compound, a group I-III-VI compound, a group III-V compound, a group III-II-V compound, a group IV-VI compound, a group IV element, a group IV compound, and a combination thereof.

10. In paragraph 1, The above quantum dot is a quantum dot complex comprising two or more elements selected from elements of Group II and Group VI, excluding Cd.

11. In paragraph 10, The above quantum dot is a quantum dot composite containing ZnSeTe.

12. In paragraph 1, A quantum dot complex that absorbs light of 300 nm to 450 nm.

13. First electrode; A second electrode facing the first electrode; A light-emitting layer disposed between the first electrode and the second electrode and including a quantum dot complex; and A functional layer disposed between the light-emitting layer and the first electrode, and between the light-emitting layer and the second electrode; The above quantum dot complex is quantum dots; A first ligand that binds to the surface of the quantum dot and includes a thiol group at one end; and A light-emitting device comprising a second ligand, which is different from the first ligand and is bound to the surface of the quantum dot and includes a thiol group at one end and a carboxyl group at the other end.

14. In paragraph 13, The first ligand comprises a first head portion comprising a thiol group, and a first tail portion extending from the first head portion and comprising an alkyl group, A light emitting element wherein the second ligand comprises a second head portion comprising a thiol group, a terminal portion spaced from the surface of the anode point and comprising a carboxyl group, and a second tail portion disposed between the second head portion and the terminal portion.

15. In paragraph 13, The above second ligand is a light-emitting element represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, n is an integer greater than or equal to 1 and less than or equal to 20, R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

16. In paragraph 13, The second ligand comprises at least one of the following compounds LD1 to LD4: .

17. In paragraph 13, The above functional layer A first functional layer disposed between the first electrode and the light-emitting layer; and A second functional layer disposed between the light-emitting layer and the second electrode; A light-emitting device wherein one of the first functional layer and the second functional layer is a hole transport region and the other is an electron transport region.

18. In paragraph 13, The above functional layer It comprises a hole transport region arranged below the light-emitting layer, and an electron transport region arranged above the light-emitting layer, The above electron transport region is formed from a common layer composition including an electron transport material and an organic solvent, A light-emitting device wherein the contact angle of the organic solvent with respect to the light-emitting layer is 15 degrees or less.

19. Circuit layer; and A display element layer disposed on the circuit layer and including a pixel definition film in which a light-emitting element and a pixel opening are defined; The above light emitting element First electrode; A second electrode facing the first electrode; A light-emitting layer disposed between the first electrode and the second electrode and including a quantum dot complex; and A functional layer disposed between the light-emitting layer and the first electrode, and between the light-emitting layer and the second electrode; The above quantum dot complex is quantum dots; A first ligand that binds to the surface of the quantum dot and includes a thiol group at one end; and A display device comprising a second ligand, which is different from the first ligand and is bound to the surface of the quantum dot and includes a thiol group at one end and a carboxyl group at the other end; 20. In paragraph 19, The first ligand comprises a first head portion comprising a thiol group, and a first tail portion extending from the first head portion and comprising an alkyl group, A display device wherein the second ligand comprises a second head portion comprising a thiol group, a terminal portion spaced from the surface of the anode point and comprising a carboxyl group, and a second tail portion disposed between the second head portion and the terminal portion.

21. In paragraph 19, The second ligand is a display device represented by the following chemical formula 1: [Chemical Formula 1] In the above chemical formula 1, n is an integer greater than or equal to 1 and less than or equal to 20, R is a hydrogen atom, a deuterium atom, a substituted or unsubstituted thiol group, a substituted or unsubstituted amine group, or a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms.

22. In paragraph 19, The second ligand is a display device comprising at least one of the following compounds LD1 to LD4: .

23. In paragraph 19, The above functional layer A first functional layer disposed between the first electrode and the light-emitting layer; and A second functional layer disposed between the light-emitting layer and the second electrode; A display device wherein one of the first functional layer and the second functional layer is a hole transport region and the other is an electron transport region.

24. In paragraph 19, The above light-emitting layer is placed within the pixel opening, A display device in which the above functional layer is a common layer overlapping the light-emitting layer and the pixel definition film.

25. In paragraph 19, The light-emitting element comprises a first light-emitting element including a first light-emitting layer emitting blue light, a second light-emitting element including a second light-emitting layer emitting green light, and a third light-emitting element including a third light-emitting layer emitting red light. A display device, wherein at least one of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer includes the quantum dot complex.

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