Electroluminescent display device

Abstract

The present invention relates to an electroluminescent (EL) display device comprising a red pixel, a green pixel, and a blue pixel. The device comprises a first electrode and a second electrode facing each other; And, the quantum dot emitting layer is disposed between the first electrode and the second electrode and does not contain cadmium, and the quantum dot emitting layer comprises a red emitting layer disposed within the red pixel and comprising a plurality of red emitting quantum dots, a green emitting layer disposed within the green pixel and comprising a plurality of green emitting quantum dots, and a blue emitting layer disposed within the blue pixel and comprising blue emitting quantum dots, wherein the blue emitting layer is configured to exhibit a blue light emission peak and a first emitting peak different from the blue light emission peak when voltage is applied, and the first wavelength difference between the blue light emission peak and the first emitting peak is 20 nm or more and 150 nm or less, or the green emitting layer is configured to exhibit a green light emission peak and a second emitting peak different from the green light emission peak when voltage is applied, and the second wavelength difference between the green light emission peak and the second emitting peak is 10 nm or more and 150 nm or less.

Description

Technology Field

[0001] The present disclosure relates to an electroluminescent display device. Background Technology

[0002] Luminescent nanostructures such as quantum dots (hereinafter referred to as quantum dots) are semiconductor materials in the form of particles having a nanoscale size. Quantum dots can exhibit a quantum confinement effect. Luminescence of quantum dots can occur, for example, as electrons in an excited state transition from the conduction band to the valence band by photoexcitation or the application of voltage. Quantum dots can be controlled to emit light in a desired wavelength range by controlling their size and / or composition.

[0003] Electroluminescent devices including quantum dots can be used in display devices. Light emission can be induced by the application of voltage and can occur by the radiative recombination of excited charges between layers included in the device. The problem to be solved

[0004] The embodiments relate to a self-luminous display that emits light by applying voltage to a luminescent nanostructure (e.g., quantum dot).

[0005] The embodiments relate to a display device (e.g., QD-LED display) comprising a light-emitting nanostructure (e.g., quantum dot) as a light-emitting material in red / green / blue pixels. means of solving the problem

[0006] In one embodiment, the electroluminescent display device includes a red pixel, a green pixel, and a blue pixel, and the device,

[0007] A first electrode and a second electrode facing each other; and,

[0008] A quantum dot light-emitting layer disposed between the first electrode and the second electrode and not containing cadmium, and

[0009] The above quantum dot light-emitting layer comprises a red light-emitting layer disposed within the red pixel and including a plurality of red light-emitting quantum dots, a green light-emitting layer disposed within the green pixel and including a plurality of green light-emitting quantum dots, and a blue light-emitting layer disposed within the blue pixel and including blue light-emitting quantum dots.

[0010] The blue light-emitting layer is configured to exhibit a blue light emission peak and a first emission peak different from the blue light emission peak when voltage is applied, and the first wavelength difference between the blue light emission peak and the first emission peak is 20 nm or more and 150 nm or less, or

[0011] Alternatively, the green light-emitting layer is configured to exhibit a green light emission peak and a second light-emitting peak different from the green light emission peak when voltage is applied, and the second wavelength difference between the green light emission peak and the second light-emitting peak is 10 nm or more and 150 nm or less (e.g., 100 nm or less).

[0012] The first wavelength difference may be 30 nm or more, 40 nm or more, or 50 nm or more. The first wavelength difference may be 120 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, or 70 nm or less.

[0013] The first emission peak may exist in a longer wavelength region than the blue light emission peak.

[0014] The second wavelength difference may be 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more. The second wavelength difference may be 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, or 20 nm or less.

[0015] The second emission peak may exist in a longer wavelength region than the green light emission peak. The second emission peak may exist in a shorter wavelength region than the green light emission peak.

[0016] The ratio of the intensity of the first emission peak to the blue light emission peak may be 0.05 or more, 0.1 or more, or 0.15 or more.

[0017] The ratio of the intensity of the first emission peak to the blue light emission peak may be 0.6 or less, 0.3 or less, 0.2 or less, or 0.15 or less.

[0018] The above blue light-emitting layer can have Cx values ​​of 0.14 or higher and 0.18 or lower in CIE color coordinates.

[0019] The above blue light-emitting layer can exhibit Cy values ​​of 0.06 or higher and 0.11 or lower in CIE color coordinates.

[0020] The blue light-emitting layer may further include a plurality of first quantum dots configured to emit light of the first light-emitting peak.

[0021] The first quantum dots mentioned above may have a composition different from the blue emitting quantum dots.

[0022] The above blue light-emitting quantum dots may include zinc chalcogenides containing tellurium.

[0023] The above blue light-emitting quantum dots may include a semiconductor nanocrystal core comprising zinc, tellurium, and selenium, and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and having a composition different from that of the semiconductor nanocrystal core.

[0024] The molar ratio of tellurium to selenium in the above blue-emitting quantum dots may be 0.1 or less, 0.05 or less, 0.03 or less, 0.02 or less, or 0.01 or less.

[0025] The plurality of first quantum dots mentioned above can be configured to emit green light.

[0026] The plurality of first quantum dots (or cores included therein) are group III-V compounds comprising indium, phosphorus, and optionally zinc, zinc selenide telluride (ZnTe y Se 1-y ) (where y is 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more and 0.9 or less, 0.8 or less, 0.7 or less), zinc telluride, or a combination thereof.

[0027] The first quantum dots may include a first semiconductor nanocrystal core comprising indium and phosphorus, and a first semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal and comprising a group II-VI compound.

[0028] The first quantum dots include zinc, selenium, and tellurium, and the molar ratio of tellurium to selenium (Te / Se) in the first quantum dots may be 0.03 or more, 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, or 0.4 or more and / or 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, or 0.3 or less.

[0029] In the blue light-emitting layer, the blue light-emitting quantum dots and the first quantum dots may be mixed (e.g., arbitrarily in the thickness direction or randomly without layer separation).

[0030] The green light-emitting layer is configured to emit light of the second light-emitting peak and may further include (multiple) second quantum dot(s) having a composition different from that of the green light-emitting quantum dots.

[0031] In the green light-emitting layer, the green light-emitting quantum dots or the second quantum dots are a Group III-V compound comprising indium, phosphorus, and optionally zinc, zinc selenide telluride (ZnTe y Se 1-y ) (where y is 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more and 0.9 or less, 0.8 or less, 0.7 or less), zinc telluride, or a combination thereof.

[0032] The above green light-emitting quantum dots or the above second quantum dots may include a semiconductor nanocrystal core comprising the above III-V group compound and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and having a composition different from that of the semiconductor nanocrystal core.

[0033] The above green light-emitting quantum dots or the above second quantum dots may include a semiconductor nanocrystalline core comprising zinc selenide telluride and a semiconductor nanocrystalline shell comprising zinc chalcogenide.

[0034] The ratio of the intensity of the second emission peak to the green light emission peak may be 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, or 0.25 or more.

[0035] The ratio of the intensity of the second emission peak to the green light emission peak may be 0.6 or less, 0.5 or less, 0.3 or less, 0.25 or less, 0.2 or less, 0.15 or less, or 0.1 or less.

[0036] The above device has a maximum luminance of 100,000 cd / m² of green pixel (light). 2 Above, for example, 110,000 cd / m 2 Above, 120,000 cd / m 2 Above, 130,000 cd / m 2 Above, 140,000 cd / m 2 Above, or 150,000 cd / m 2 It could be more than that.

[0037] The above device has a maximum luminance of 36,000 cd / m² of blue pixel (light). 2 Above, or 40,000 cd / m 2 It could be more than that.

[0038] The above device may have a maximum EQE of 9% or more, or 9.5% or more, of a blue pixel (or blue light-emitting layer).

[0039] A charge auxiliary layer may be included in at least one of the space between the first electrode and the quantum dot light-emitting layer and the space between the second electrode and the quantum dot light-emitting layer.

[0040] In the above device, the first electrode includes an anode, and

[0041] A hole injection layer, a hole transport layer, an electron blocking layer, or a combination thereof is included between the first electrode and the quantum dot light-emitting layer.

[0042] The second electrode above includes a cathode, and

[0043] Between the second electrode and the quantum dot light-emitting layer, an electron injection layer, an electron transport layer, a hole blocking layer, or a combination thereof may be included. Effects of the invention

[0044] According to embodiments, a single pixel can be implemented by mixing quantum dots that emit light of different colors. According to embodiments, a display device comprising a pixel capable of emitting light of a desired color is provided. The display device according to the embodiments can emit light (e.g., blue light) adjusted to satisfy desired color coordinates (e.g., with increased brightness). Brief explanation of the drawing

[0045] Figure 1 shows a schematic cross-sectional view of a display device according to one embodiment. FIG. 2 shows a schematic cross-sectional view of a display device according to another embodiment. FIG. 3a is a schematic cross-sectional view of a quantum dot light-emitting layer included in a display device according to one embodiment. FIG. 3b is a schematic cross-sectional view of a quantum dot light-emitting layer included in a display device according to one embodiment. Figure 4 shows the photoluminescence spectrum of quantum dots prepared in the example. FIG. 5 shows the electroluminescence spectrum of a blue light-emitting layer in a display device according to one embodiment. Specific details for implementing the invention

[0046] Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0047] To clearly explain the present invention, parts unrelated to the explanation have been omitted, and the same reference numerals are used for identical or similar components throughout the specification.

[0048] Furthermore, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, and thus the present invention is not necessarily limited to what is illustrated. Thicknesses have been enlarged in the drawings to clearly represent various layers and regions. Additionally, for convenience of explanation, the thickness of some layers and regions has been exaggerated in the drawings.

[0049] Furthermore, when it is said that a part, such as a layer, membrane, region, or plate, is "on" or "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when it is said that a part is "directly above" another part, it means that there is no other part in between. Also, saying that a part is "on" or "on" a reference part means that it is located above or below the reference part, and does not necessarily mean that it is located "on" or "on" in the direction opposite to gravity.

[0050] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0051] Additionally, throughout the specification, "planar" means when the subject part is viewed from above, and "cross-sectional" means when the cross-section obtained by vertically cutting the subject part is viewed from the side.

[0052] In addition, the singular form includes the plural form unless specifically mentioned otherwise in the phrase.

[0053] Thicknesses have been enlarged in the drawings to clearly represent various layers and regions. Throughout the specification, the same reference numerals have been used for similar parts.

[0054] Unless otherwise defined below, "substitution" means that a compound or its residue, instead of hydrogen, comprises a C1 to C30 alkyl group, a C1 to C30 alkenyl group, a C2 to C30 alkynyl group, a C6 to C30 aryl group, a C7 to C30 alkylaryl group, a C1 to C30 alkoxy group, a C1 to C30 heteroalkyl group, a C3 to C30 heteroalkylaryl group, a C3 to C30 cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C30 cycloalkynyl group, a C2 to C30 heterocycloalkyl group, a halogen (-F, -Cl, -Br, or -I), a hydroxyl group (-OH), a nitro group (-NO2), a cyano group (-CN), an amino group (-NRR', where R and R' are independently hydrogen or a C1 to C6 alkyl group), It means substituted with a substituent selected from an azido group (-N3), an amidino group (-C(=NH)NH2)), a hydrazino group (-NHNH2), a hydrazono group (-N(NH2)), an aldehyde group (-C(=O)H), a carbamoyl group (-C(O)NH2), a thiol group (-SH), an ester group (-C(=O)OR, where R is a C1 to C6 alkyl group or a C6 to C12 aryl group), a carboxyl group (-COOH) or its salt (-C(=O)OM, where M is an organic or inorganic cation), a sulfonic acid group (-SO3H) or its salt (-SO3M, where M is an organic or inorganic cation), a phosphate group (-PO3H2) or its salt (-PO3MH or -PO3M2, where M is an organic or inorganic cation) and combinations thereof.

[0055] Here, the description that it does not contain cadmium (or other toxic heavy metals) may refer to a concentration of cadmium (or said heavy metal) of 100 ppm or less, 50 ppm or less, 10 ppm or less, or nearly 0. In one embodiment, cadmium (or said heavy metal) is substantially absent, or even if it is present, it is present in an amount below the detection limit of a given detection means or at an impurity level.

[0056] The term "quantum dot" here refers to a luminescent (e.g., capable of emitting light upon energy excitation) nanostructure comprising a nanocrystal (e.g., semiconductor-based) exhibiting quantum confinement or exciton confinement. The shape of the term "quantum dot" is not limited unless specifically defined otherwise. Here, "nanostructure" refers to at least one region having nanoscale dimensions or a structure having characteristic dimensions. In one embodiment, the dimensions of the nanostructure may be less than about 300 nm, less than about 250 nm, less than about 150 nm, less than about 100 nm, less than about 50 nm, or less than about 30 nm. These structures may have any shape. The nanostructures may have any shape, such as nanowires, nanorods, nanotubes, multi-pod type shapes having two or more pods, nanodots (or quantum dots), etc., and are not particularly limited. Nanostructures can be, for example, substantially crystalline, substantially single-crystalline, polycrystalline, amorphous, or a combination thereof.

[0057] Color reproduction rate (for example, according to DCI standards) refers to the ratio of the color gamut of an electroluminescent display device to the color gamut according to standards set in CIE color coordinates (i.e., the ratio of the area of ​​the matching part to the total area of ​​the standard color gamut).

[0058] Luminescent nanostructures such as quantum dots (hereinafter referred to as quantum dots) can have a size smaller than the diameter of a Bohr excitation in a bulk crystal of the same material and can exhibit a quantum confinement effect. Quantum dots can emit light corresponding to their bandgap energy by controlling the size of the luminescence center of the nanocrystal.

[0059] The energy bandgap of quantum dots can vary depending on the size, structure, and composition of the nanocrystals. For example, as the size of quantum dots increases, they may have a narrower energy bandgap and an increased emission wavelength. Semiconductor nanocrystals are attracting attention as light-emitting materials in various fields, such as display devices, energy devices, or bioluminescent devices. Quantum dots with electroluminescent properties suitable for practical applications may contain harmful heavy metals, such as cadmium (Cd), lead, mercury, or combinations thereof. For applications in QLED displays, light-emitting materials configured to emit light of a desired color coordinate (e.g., quantum dots capable of emitting pure blue light) are required.

[0060] For example, in realizing desired blue light, non-cadmium InP-containing quantum dots face the difficulty of requiring a very small core (e.g., 1 to 2 nm). Non-cadmium ZnSe-based quantum dots emit deep blue light with a high bandgap. Te-doped ZnTeSe-based quantum dots can realize blue light of the desired wavelength. However, if the Te content is increased to realize accurate blue light, emission in the long-wavelength region occurs; therefore, it is desirable to develop a display device configured to emit light of the desired color coordinates in the CIE 1931 or xy color space.

[0061] A display device according to one embodiment includes a self-luminous type light-emitting element configured to emit a desired light by applying voltage without a separate light source.

[0062] In one embodiment, an electroluminescent display device comprises a red pixel, a green pixel, and a blue pixel, and the device comprises a first electrode and a second electrode facing each other; and a quantum dot light-emitting layer disposed between the first electrode and the second electrode and not containing cadmium. The first electrode may comprise an anode, and the second electrode may comprise a cathode. Alternatively, the first electrode may comprise a cathode and the second electrode may comprise an anode. In the electroluminescent display device, the first electrode or the second electrode may be disposed on a (transparent) substrate. The transparent substrate may be a light-extracting surface. (See FIG. 1 and FIG. 2)

[0063] The quantum dot light-emitting layer comprises a red light-emitting layer disposed within the red pixel and including a plurality of red light-emitting quantum dots, a green light-emitting layer disposed within the green pixel and including a plurality of green light-emitting quantum dots, and a blue light-emitting layer disposed within the blue pixel and including blue light-emitting quantum dots.

[0064] A schematic cross-sectional view of a display device according to one embodiment is shown in FIGS. 1 and FIGS. 2.

[0065] In FIGS. 1 and 2, a quantum dot light-emitting layer (30) may be disposed between a first electrode (e.g., anode) (10) and a second electrode (e.g., cathode) (50).

[0066] The above cathode (50) may include an electron injection conductor. The above anode (10) may include a hole injection conductor. The work function of the electron / hole injection conductors included in the cathode and the anode can be appropriately adjusted and is not particularly limited. For example, the cathode may have a small work function and the anode may have a relatively large work function, or vice versa.

[0067] Electron / hole injection conductors may include, but are not limited to, metal-based materials (e.g., metals, metal compounds, alloys, combinations thereof) (e.g., aluminum, magnesium, tungsten, nickel, cobalt, platinum, palladium, calcium, LiF, etc.), metal oxides such as gallium indium oxide, indium tin oxide (ITO), or conductive polymers (e.g., having a relatively high work function) such as polyethylenedioxythiophene.

[0068] At least one of the first electrode and the second electrode may be a light-transmitting electrode or a transparent electrode. In one embodiment, both the first electrode and the second electrode may be light-transmitting electrodes. The electrode(s) may be patterned. The first electrode and / or the second electrode may be disposed on a substrate (e.g., insulating). The substrate may be optically transparent (e.g., having a light transmittance of 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, or 90% or more, and e.g., 99% or less, or 95% or less). The substrate may include an area for a red pixel, an area for a green pixel, and an area for a blue pixel. A thin-film transistor may be disposed in each of the areas of the substrate, and one of the source electrode and drain electrode of the thin-film transistor may be electrically connected to the first electrode or the second electrode.

[0069] The light-transmitting electrode may be placed on a transparent substrate (e.g., insulating). The substrate may be rigid or flexible. The substrate may be plastic, glass, or metal.

[0070] The light-transmitting electrode may be made of a transparent conductor such as, for example, indium tin oxide (ITO) or indium zinc oxide (IZO), gallium indium tin oxide, zinc indium tin oxide, titanium nitride, polyaniline, LiF / Mg:Ag, etc., or a thin single-layer or multi-layer metal film, but is not limited thereto. If one of the first electrode and the second electrode is an opaque electrode, it may be made of an opaque conductor such as, for example, aluminum (Al), lithium aluminum (Li:Al) alloy, magnesium-silver alloy (Mg;Ag), or lithium fluoride-aluminum (LiF:Al).

[0071] The thickness of the electrode (first electrode and / or second electrode) is not particularly limited and can be appropriately selected considering the device efficiency. For example, the thickness of the electrode may be 5 nm or more, e.g., 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more. For example, the thickness of the electrode may be 100 μm or less, e.g., 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, 10 μm or less, 1 μm or less, 900 nm or less, 500 nm or less, or 100 nm or less.

[0072] The quantum dot emitting layer (30) disposed between the first electrode and the second electrode (e.g., anode (10) and cathode (50)) comprises a plurality of quantum dots. The plurality of quantum dots do not contain cadmium. The quantum dot emitting layer may comprise one or more (e.g., two or more, or three or more and 10 or fewer) monolayers of the plurality of quantum dots. The plurality of quantum dots may comprise quantum dots with a core-shell structure.

[0073] The quantum dot emitting layer may be patterned. In one embodiment, the patterned quantum dot emitting layer may include a red emitting layer disposed within the red pixel, a green emitting layer disposed within the green pixel, and a blue emitting layer disposed within the blue pixel. A barrier such as a black matrix (BM) may be disposed between the red emitting layer, the green emitting layer, and the blue emitting layer. (See FIG. 3a and FIG. 3b) The red emitting layer, the green emitting layer, and the blue emitting layer may each be optically isolated.

[0074] In a display device of one embodiment, the red pixel (or red emitting quantum dot) may display an emission peak wavelength (e.g., electroluminescence (EL) peak wavelength) in a range of 600 nm or more, e.g., 615 nm or more, 625 nm or more, 628 nm or more, and 640 nm or less, or 635 nm or less, and 630 nm or less. The green pixel (or green emitting quantum dot) may display an emission peak wavelength (e.g., electroluminescence (EL) peak wavelength) in a range of 500-550 nm, 510-540 nm, and 525 nm to 536 nm (e.g., 526 nm to 535 nm or 527 nm to 534 nm). The above green pixel or (green light-emitting quantum dot) may have an emission peak wavelength (e.g., electroluminescence (EL) peak wavelength) of 524 nm or more, or 525 nm or more and 545 nm or less, or 536 nm or less (e.g., about 526 nm to about 545 nm, or about 527 nanometers (nm) to about 535 nm). The above green pixel or (green light-emitting quantum dot) may be 520 nm or more, 524 nm or more, and 535 nm or less. The above blue pixel or blue light-emitting quantum dot may exhibit an emission peak wavelength (e.g., electroluminescence (EL) peak wavelength) in the range of 420 nm or more, 430 nm or more, 435 nm or more, 440 nm or more, 445 nm or more, 450 nm or more, or 451 nm or more and 460 nm or less, e.g., 458 nm or less, or 455 nm or less.

[0075] The red-emitting quantum dots included in the above red pixel may have any composition. In one embodiment, at least some of the red-emitting quantum dots may have a (semiconductor nanocrystal) core comprising indium (In), phosphorus (P), and optionally zinc (Zn), and a (semiconductor nanocrystal) shell disposed on the surface of the core comprising zinc, sulfur, and optionally selenium. The shell may be a multilayer shell in which adjacent layers have different compositions. In the red-emitting quantum dots, the core may comprise InP or InZnP, and the shell may comprise ZnS, ZnSe, ZnSeS, or a combination thereof. The shell may be a multilayer shell of two or more layers, and each layer may have a different composition. The shell may have a composition that varies in the radial direction.

[0076] In one embodiment, the red-emitting quantum dot may have an emission peak wavelength of 620 nm or more, e.g., 622 nm or more, 623 nm or more, 624 nm or more, 625 nm or more, 626 nm or more, 627 nm or more, and 650 nm or less, 645 nm or less, 640 nm or less, 637 nm or less, or 630 nm or less. The red-emitting quantum dot may exhibit a quantum yield of 80% or more, e.g., 85% or more, 89% or more, or 90% or more. The shape of the red-emitting quantum dot(s) particles is not particularly limited. The shape of the red-emitting quantum dot(s) particles may include a sphere, a polyhedron, a multipod, or a combination thereof. The above red-emitting quantum dot(s) may have an (average) size of 5 nm or more, e.g. 6 nm or more and 15 nm or less, 10 nm or less, e.g. 9 nm or less or 8.8 nm or less.

[0077] As explained above, it may not be easy for a quantum dot emissive layer containing non-cadmium quantum dots to emit light capable of exhibiting desired color coordinates. Although zinc selenium telluride-based quantum dots can emit blue light in the desired wavelength range, the inventors have confirmed that as the tellurium content increases, the emission peak can widen and consequently exhibit an increased full width at half maximum (cf. FIG. 4).

[0078] In a display device according to one embodiment, the blue light-emitting layer or the green light-emitting layer may be configured to have different center wavelengths when voltage is applied and to exhibit two different light-emitting peaks having different full widths, for example, and thereby emit light closer to a desired color. Although not intended to be bound by any specific theory, the display device of one embodiment may emit light closer to a desired color coordinate and / or exhibit enhanced brightness by including a mixed light-emitting layer as described above.

[0079] Accordingly, in a display device of one embodiment, for example, the blue light-emitting layer is configured to exhibit a blue light emission peak and a first light-emitting peak different from the blue light emission peak when voltage is applied, and the first wavelength difference between the blue light emission peak and the first light-emitting peak may be 20 nm or more (or 30 nm or more) and 150 nm or less (or 100 nm or less).

[0080] The blue emitting layer may further include a plurality of first quantum dots (G) configured to emit light of the first emission peak (e.g., green light) together with the blue emitting quantum dots (B). The first quantum dots may have a composition different from that of the blue emitting quantum dots. (See FIG. 3a)

[0081] The above blue-emitting quantum dots may include a zinc chalcogenide containing tellurium. The above blue-emitting quantum dots may include a zinc chalcogenide not containing tellurium. The content of tellurium in the above blue-emitting quantum dots may be less than the content of selenium, sulfur, or a combination thereof.

[0082] The above blue light-emitting quantum dots may include a semiconductor nanocrystal core comprising zinc, tellurium, and selenium, and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and having a composition different from that of the semiconductor nanocrystal core.

[0083] The first semiconductor nanocrystalline material of the core may contain a limited amount of tellurium (Te). The core is ZnTe x Se 1-x (Here, x is greater than 0 and less than or equal to 0.1) may be included. In the core, the content of tellurium (or the value of x in the above formula) per 1 mole of selenium may be 0.001 mole or more, 0.005 mole or more, 0.006 mole or more, 0.007 mole or more, 0.008 mole or more, 0.009 mole or more, 0.01 mole or more, 0.015 mole or more, or 0.02 mole or more. In the above core, the content of tellurium may be 0.06 moles or less, 0.053 moles or less, for example, 0.05 moles or less, 0.049 moles or less, 0.048 moles or less, 0.047 moles or less, 0.046 moles or less, 0.045 moles or less, 0.044 moles or less, 0.043 moles or less, 0.042 moles or less, 0.041 moles or less, 0.04 moles or less, or 0.035 moles or less.

[0084] The shell may contain zinc (Zn), selenium (Se), and sulfur (S). The shell may be a multilayer shell. The multilayer shell may include a first layer disposed immediately above the core and an outer layer (e.g., outermost layer) disposed on the first layer, wherein the first layer may contain ZnSe, ZnSeS, or a combination thereof. The outer layer or the outermost layer may contain ZnS. The shell may be a gradient alloy, and the sulfur content may have a concentration gradient that increases (or decreases) as it moves away from the core.

[0085] In the above blue-emitting quantum dots, for example, when measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), the molar ratio of tellurium to selenium may be 0.1 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less, 0.009 or less, or 0.0089 or less. In the above blue-emitting quantum dots, the molar ratio of tellurium to selenium may be 0.0001 or more, 0.0005 or more, 0.0009 or more, 0.001 or more, 0.002 or more, 0.003 or more, 0.004 or more, or 0.005 or more. The molar ratio of tellurium to selenium may be 0.004 to 0.025. In the above blue-emitting quantum dots, the zinc content may be greater than the selenium content. The blue-emitting quantum dot(s) particles (e.g., confirmed by ICP-AES analysis) may have a zinc (Zn) content greater than the selenium (Se) content, and a selenium content greater than the tellurium content.

[0086] For example, when confirmed by ICP-AES analysis, the molar ratio of Se to Zn in the blue-emitting quantum dot(s) may be less than 1, e.g., 0.95 or less, 0.90 or less, 0.85 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less. The molar ratio of Se to Zn may be 0.05 or more, e.g., 0.1 or more, or 0.2 or more.

[0087] For example, when confirmed by ICP-AES analysis, the molar ratio of Te to Zn in the blue-emitting quantum dot(s) may be 0.03 or less, e.g., 0.027 or less, 0.025 or less, 0.02 or less, 0.019 or less, 0.018 or less, 0.017, 0.016 or less, 0.015 or less, 0.01 or less, 0.009 or less, 0.008 or less, 0.007 or less, 0.006 or less, or 0.005 or less. The molar ratio of Te to Zn may be 0.0005 or more, 0.0009 or more, 0.001 or more, 0.002 or more, 0.003 or more, 0.005 or more, or 0.009 or more. In the blue-emitting quantum dot(s) particles according to one embodiment, the tellurium content may be 1 weight% or less based on the total weight of the semiconductor nanocrystalline particles. The blue-emitting quantum dot(s) particles may not contain cadmium, lead, or a combination thereof. The (blue-emitting semiconductor) nanocrystalline particles may not contain copper, manganese, or a combination thereof.

[0088] The molar ratio of sulfur to Zn in the above blue-emitting quantum dot(s) may be 0.1 or more, e.g. 0.15 or more, 0.2 or more, or 0.3 or more. The molar ratio of sulfur to Zn in the above blue-emitting quantum dot(s) may be 0.9 or less, e.g. 0.8 or less, 0.7 or less, or 0.6 or less. The molar ratio of Se + S to zinc in the above blue-emitting quantum dot(s) may be 0.3 or more, 0.4 or more, or 0.5 or more. The molar ratio of Se + S to zinc in the above semiconductor nanocrystalline particles may be 1 or less, e.g. less than 1, and 0.5 or more, e.g. 0.6 or more, 0.7 or more, or 0.8 or more. The ratio of sulfur to selenium in the above blue-emitting quantum dot(s) may be 0.5 or more and 2 or less.

[0089] The shape of the blue-emitting quantum dot(s) is not particularly limited. The shape of the quantum dots may include spherical, polygonal, multipod, or a combination thereof. In one embodiment, the blue-emitting quantum dot(s) may include a multipod shape. The multipod may have two or more (e.g., three or more or four or more) branch sections and valley sections between them.

[0090] The average size of the core in the above blue-emitting quantum dot(s) may be 2 nm or more, 3 nm or more, or 4 nm or more. The average size of the core may be 6 nm or less, for example, 5 nm or less. The size (or average size, hereinafter referred to as size) of the above blue-emitting quantum dot(s) may be 3 nm or more, for example, 4 nm or more, 5 nm or more, 6 nm or more, 7 nm or more, 8 nm or more, 9 nm or more, 10 nm or more, 11 nm or more, or 12 nm or more. The size of the above blue-emitting quantum dot(s) may be 50 nm or less, for example, 40 nm or less, 35 nm or less, 29 nm or less, 28 nm or less, 27 nm or less, 26 nm or less, 25 nm or less, 24 nm or less, 23 nm or less, 22 nm or less, 21 nm or less, 20 nm or less, 19 nm or less, 18 nm or less, 17 nm or less, 16 nm or less, 15 nm or less, 14 nm or less, 13 nm or less, or 12 nm or less. In this specification, the (average) size of the quantum dot(s) may refer to the equivalent diameter calculated from a two-dimensional image confirmed by an electron microscope. In this specification, the size of the quantum dot(s) may also be confirmed from the composition confirmed by inductively coupled plasma atomic emission analysis, etc.

[0091] The blue emitting quantum dot(s) according to one embodiment may exhibit (photo- or electric field) emission peak wavelengths of 430 nm or more (e.g., 435 nm or more, 440 nm or more, 446 nm or more, 449 nm or more, or 450 nm or more) and 480 nm or less (e.g., 470 nm or less, 465 nm or less, 460 nm or less, or 455 nm or less).

[0092] The maximum emission peak of the above blue-emitting quantum dot(s) may have a full width at half maximum (FWHM) of 50 nm or less, e.g., 49 nm or less, 48 ​​nm or less, 47 nm or less, 46 nm or less, 45 nm or less, 44 nm or less, 43 nm or less, 42 nm or less, 41 nm or less, 40 nm or less, 39 nm or less, 38 nm or less, 37 nm or less, 36 nm or less, 35 nm or less, 34 nm or less, 33 nm or less, 32 nm or less, 31 nm or less, 30 nm or less, 29 nm or less, or 28 nm or less. The FWHM of the emission peak of the blue-emitting quantum dot(s) may be 12 nm or more, 20 nm or more, 25 nm or more, or 26 nm or more.

[0093] The above blue emitting quantum dot(s) may have a quantum efficiency (or quantum yield) of 60% or more, e.g., 61% or more, 62% or more, 63% or more, 64% or more, 65% or more, 66% or more, 67% or more, 68% or more, 69% or more, 70% or more, or 71% or more. The above blue emitting quantum dot(s) may exhibit a quantum efficiency of 80% or more, 90% or more, 95% or more, 99% or more, or 100%.

[0094] In one embodiment, in the blue light emitting layer, the first wavelength difference between the blue emission peak and the first emission peak may be 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, 50 nm or more, 55 nm or more, 60 nm or more, 65 nm or more, 70 nm or more, or 75 nm or more. The first wavelength difference may be 140 nm or more, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, or 50 nm or less.

[0095] The first emission peak may exist in a wavelength region longer than the blue light emission peak. The first emission peak may exist in a green light region. The green light region may be 490 nm or more, 500 nm or more, 510 nm or more, 515 nm or more, 520 nm or more, 525 nm or more, 530 nm or more, or 535 nm or more. The green light region may be 560 nm or less, 555 nm or less, 550 nm or less, 545 nm or less, 540 nm or less, 535 nm or less, 530 nm or less, or 525 nm or less.

[0096] In one embodiment, the plurality of first quantum dots included in the blue light-emitting layer may be configured to emit green light. The plurality of first quantum dots may include a Group III-V compound comprising indium, phosphorus, and optionally zinc, zinc selenide telluride, zinc telluride, or a combination thereof. In one embodiment, the plurality of first quantum dots (e.g., configured to emit green light) may include a semiconductor nanocrystal core and a semiconductor nanocrystal shell disposed on the core and comprising a Group II-VI compound. The semiconductor nanocrystal core may include indium phosphide, indium zinc phosphide, or a combination thereof. In another embodiment, the semiconductor nanocrystal core may include ZnTeSe.

[0097] In one embodiment, the first quantum dots comprise zinc, selenium, and tellurium, and the molar ratio of tellurium to selenium within the first quantum dots may be 0.1 or greater, or 0.15 or greater. Additionally, for details regarding the plurality of first quantum dots (e.g., emitting green light), refer to the details regarding the green-emitting quantum dots included in the green-emitting layer described below.

[0098] In the blue emitting layer, the content of the plurality of first quantum dots may be 0.1 wt% or more, 0.5 wt% or more, 1 wt% or more, 1.5 wt% or more, 2 wt% or more, 2.5 wt% or more, 3 wt% or more, or 3.5 wt% or more, based on the total weight of the blue emitting quantum dots. In the blue emitting layer, the content of the plurality of first quantum dots may be 10 wt% or less, 9.5 wt% or less, 9 wt% or less, 8.5 wt% or less, 8 wt% or less, 7.5 wt% or less, 7 wt% or less, or 6.5 wt% or less, based on the total weight of the blue emitting quantum dots.

[0099] In one embodiment, the blue emitting quantum dots and the first quantum dots in the blue emitting layer may be mixed (e.g., arbitrarily in the thickness direction).

[0100] In the blue light emitting layer of the display element of one embodiment, the ratio of the intensity of the first emission peak to the blue light emission peak may be 0.05 or higher. In one embodiment, the ratio of the intensity of the first emission peak to the blue light emission peak may be 0.1 or higher, 0.12 or higher, 0.15 or higher, 0.17 or higher, 0.19 or higher, 0.2 or higher, 0.21 or higher, 0.23 or higher, 0.25 or higher, 0.27 or higher, 0.29 or higher, or 0.3 or higher. The ratio of the intensity of the first emission peak to the blue light emission peak may be 0.6 or lower, 0.55 or lower, 0.50 or lower, 0.45 or lower, 0.4 or lower, 0.35 or lower, 0.3 or lower, 0.25 or lower, 0.2 or lower, or 0.15 or lower.

[0101] The blue light-emitting layer of one embodiment may exhibit a Cx value of 0.14 or higher in CIE color coordinates, for example, 0.142 or higher, 0.145 or higher, 0.147 or higher, 0.149 or higher, 0.15 or higher, 0.152 or higher, 0.155 or higher, 0.157 or higher, or 0.16 or higher. The blue light-emitting layer of one embodiment may exhibit a Cx value of 0.18 or lower, 0.175 or lower, 0.17 or lower, 0.165 or lower, 0.163 or lower, or 0.16 or lower in CIE color coordinates.

[0102] The blue light-emitting layer of one embodiment may exhibit a Cy value of 0.06 or higher, 0.065 or higher, 0.067 or higher, 0.069 or higher, or 0.070 or higher and / or 0.11 or lower, 0.105 or lower, 0.095 or lower, 0.09 or lower, 0.087 or lower, 0.085 or lower, 0.083 or lower, or 0.085 or lower in CIE color coordinates.

[0103] In a display device of one embodiment, for example, a green light-emitting layer disposed within the green pixel is configured to exhibit a green light emission peak and a second light-emitting peak different from the green light emission peak when voltage is applied, and the second wavelength difference between the green light emission peak and the second light-emitting peak may be 10 nm or more and 150 nm or less.

[0104] The second emission peak may exist in a longer wavelength region than the green light emission peak. The second emission peak may exist in a shorter wavelength region than the green light emission peak.

[0105] The second emission peak may have a center wavelength in the range of 480 nm - 580 nm, 485 nm - 575 nm, 490 nm - 570 nm, 495 nm - 565 nm, 500 nm - 560 nm, 505 nm - 555 nm, 510 nm - 550 nm, 515 nm - 545 nm, 520 nm - 540 nm, 525 nm - 535 nm, or 530 nm - 538 nm, or a combination thereof.

[0106] The second wavelength difference may be 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, or 50 nm or more. The second wavelength difference may be 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 65 nm or less, 60 nm or less, 55 nm or less, 50 nm or less, 45 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, or 18 nm or less.

[0107] The green light-emitting layer is configured to emit light of the second emission peak together with the green light-emitting quantum dots (G1) and may further include a plurality of second quantum dots (G2) having a composition different from that of the green light-emitting quantum dots. (See FIG. 3b)

[0108] In the green light-emitting layer, the green light-emitting quantum dot(s) or the second quantum dot(s) may comprise a Group III-V compound containing indium, phosphorus, and optionally zinc, zinc selenide telluride, zinc telluride, or a combination thereof.

[0109] In one embodiment, the green light-emitting quantum dot(s) or the second quantum dot(s) are the group III-V compound, zinc selenium telluride (ZnTe₂). y Se 1-y) (where y is 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, and 0.9 or less, 0.8 or less, 0.7 or less), or a combination thereof, may include a semiconductor nanocrystal core and a semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and having a composition different from that of the semiconductor nanocrystal core. The semiconductor nanocrystal shell may include zinc chalcogenide (zinc selenide, zinc sulfide, or a combination thereof).

[0110] The above-mentioned Group III-V compound may comprise indium (In), phosphorus (P), and optionally zinc (Zn). The core may comprise InP or InZnP. The core may comprise zinc selenium telluride (ZnTe y Se 1-y It may include ).

[0111] The shell or the zinc chalcogenide may comprise zinc and a chalcogen element (e.g., sulfur, selenium, or a combination thereof). The shell may be a multilayer shell in which adjacent layers have different compositions. The shell or the zinc chalcogenide may comprise ZnSe, ZnS, ZnSeS, or a combination thereof. In the green emitting quantum dot(s) or the second quantum dot(s), the thickness of the shell may be 1 nm or more, 1.5 nm or more, 2 nm or more, or 2.5 nm or more and 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, or 1.5 nm or less. The shell may have a composition that varies in the radial direction. For example, if the shell comprises ZnSeS, the sulfur content may increase along the radial direction, and the outermost layer of the shell may comprise ZnS or be composed of ZnS. In one embodiment, the inner layer may include or be composed of ZnSe or ZnSeS.

[0112] The above green light-emitting semiconductor nanocrystal particles can exhibit a quantum efficiency of 80% or more, for example, 85% or more.

[0113] The shape of the green emitting quantum dot(s) or the second quantum dot(s) is not particularly limited and may include a sphere, a polyhedron, a multipod, or a combination thereof. The (average) size of the green emitting quantum dot(s) or the second quantum dot(s) may be 3 nm or more, 4 nm or more, 5 nm or more, 5.5 nm or more, 6 nm or more, 6.5 nm or more, 7 nm or more, 7.5 nm or more, or 8 nm or more and 50 nm or less, 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, 20 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, or 5.5 nm or less.

[0114] In one embodiment, the green light-emitting quantum dots or the second quantum dots comprise zinc, selenium, and tellurium, and the molar ratio of tellurium to selenium (Te / Se) in the green light-emitting quantum dots or the second quantum dots may be 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, or 0.5 or more. The molar ratio of tellurium to selenium (Te / Se) in the green light-emitting quantum dots or the second quantum dots may be 4 or less, 3.5 or less, 3 or less, 2.5 or less, 2 or less, 1.5 or less, or 1 or less.

[0115] The above green light-emitting quantum dots or the above second quantum dots may not contain manganese, copper, or a combination thereof.

[0116] The above green light-emitting quantum dots or the above second quantum dots may include sulfur and selenium, wherein the ratio of sulfur (S / Se) to selenium may be greater than 0, e.g., 0.5 or more, 0.8 or more, 1 or more, or 1.2 or more and 8 or less, 7.5 or less, 7 or less, 6.5 or less, 6 or less, 5.5 or less, 5 or less, 4.5 or less, 4 or less, 3.7 or less, 3 or less, or 2.5 or less.

[0117] The intensity ratio of the second emission peak to the green light emission peak may be 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, or 0.25 or more. The intensity ratio of the second emission peak to the green light emission peak may be 0.6 or less, 0.55 or less, 0.5 or less, 0.45 or less, 0.4 or less, 0.35 or less, 0.3 or less, 0.25 or less, 0.2 or less, or 0.15 or less.

[0118] In the above display device, the thickness of the light-emitting layer can be appropriately selected. In one embodiment, the light-emitting layer may include monolayer(s) of quantum dots. In another embodiment, the light-emitting layer may include monolayers of quantum dots in one or more layers, e.g., two or more layers, three or more layers, or four or more layers and 20 or fewer layers, 10 or fewer layers, 9 or fewer layers, 8 or fewer layers, 7 or fewer layers, or 6 or fewer layers. The light-emitting layer may have a thickness of 5 nm or more, e.g., 10 nm or more, 20 nm or more, or 30 nm or more, and 200 nm or less, e.g., 150 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, or 50 nm or less. The light-emitting layer may have a thickness of, for example, about 10 nm to 150 nm, e.g., about 20 nm to 100 nm, e.g., about 30 nm to 50 nm.

[0119] The step of forming a quantum dot light-emitting layer can be performed by obtaining a composition containing quantum dots and applying or depositing it onto a substrate or a charge auxiliary layer by an appropriate method (e.g., by spin coating, inkjet printing, etc.).

[0120] The red emitting quantum dots, the green emitting quantum dots, the blue emitting quantum dots, or the first and second quantum dots having the aforementioned structure / composition can be manufactured by an appropriate method (e.g., by a wet chemical formula method).

[0121] In one embodiment, a method for manufacturing the quantum dots having, for example, a core-shell structure may comprise: obtaining the core; preparing a first shell precursor containing a metal (e.g., zinc) and a first shell precursor solution containing an organic ligand; preparing a second shell precursor containing a non-metal element (e.g., sulfur, selenium, or a combination thereof); and heating the first shell precursor solution to a reaction temperature (e.g., 180°C or higher, 200°C or higher, 240°C or higher, or 280°C or higher to 360°C or lower, 340°C or lower, or 320°C or lower) and adding the core and the second shell precursor to form a shell of a second semiconductor nanocrystal on the first semiconductor nanocrystal core. The method may further comprise the step of preparing a core solution by separating the core from the reaction system used for its manufacture and dispersing it in an organic solvent.

[0122] In one embodiment, for shell formation, a solvent and optionally a ligand compound are heated (or vacuumed) under vacuum to a predetermined temperature (e.g., 100°C or higher), then switched to an inert gas atmosphere and heated again to a predetermined temperature (e.g., 100°C or higher). Subsequently, a core is introduced, shell precursors are introduced sequentially or simultaneously, and the reaction is carried out by heating to a predetermined reaction temperature. Shell precursors may be introduced sequentially over a reaction time in mixtures of different ratios.

[0123] In the quantum dots of the first embodiment, the core can be manufactured by an appropriate method. The above organic solvent comprises a C6 to C22 primary amine such as hexadecylamine, a C6 to C22 secondary amine such as dioctylamine, a C6 to C40 tertiary amine such as trioctylamine, a nitrogen-containing heterocyclic compound such as pyridine, a C6 to C40 olefin such as octadecene, an aliphatic hydrocarbon of C6 to C40 such as hexadecane, octadecane, or squalene, an aromatic hydrocarbon substituted with a C6 to C30 alkyl group such as phenyldodecane, phenyltetradecane, or phenylhexadecane, a primary, secondary, or tertiary phosphine substituted with at least one (e.g., one, two, or three) C6 to C22 alkyl group (e.g., trioctylamine), or (e.g., one, two, or three) C6 to C22 It may include phosphine oxide substituted with an alkyl group (e.g., trioctylphosphine oxide), C12 to C22 aromatic ethers such as phenyl ether and benzyl ether, or combinations thereof.

[0124] The above organic ligand coordinates the surface of the prepared quantum dots and can enable the nanocrystals to be well dispersed in a solution. The above organic ligand may include RCOOH, RNH2, R2NH, R3N, RSH, RH2PO, R2HPO, R3PO, RH2P, R2HP, R3P, ROH, RCOOR', RPO(OH)2, R2POOH (wherein R and R' each independently comprise a C1 or higher, C6 or higher, or C10 or higher and C40 or lower substituted or unsubstituted aliphatic hydrocarbon, or a C6 to C40 substituted or unsubstituted aromatic hydrocarbon, or a combination thereof), or a combination thereof. The above ligand may be used alone or as a mixture of two or more compounds.

[0125] After the reaction is complete, adding a nonsolvent to the reaction product may separate the nanocrystalline particles coordinated with the ligand compound. The nonsolvent may be a polar solvent that is miscible with the solvent used in the core formation and / or shell formation reaction but cannot disperse the prepared nanocrystalline particles. The nonsolvent may be determined based on the solvent used in the reaction and may include, for example, acetone, ethanol, butanol, isopropanol, ethanediol, water, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), diethyl ether, formaldehyde, acetaldehyde, ethylene glycol, solvents having solubility parameters similar to those listed above, or combinations thereof. Separation may be achieved using centrifugation, precipitation, chromatography, or distillation. The separated nanocrystalline particles may be washed by adding a washing solvent as necessary. The cleaning solvent is not particularly limited and may use a solvent having a solubility parameter similar to that of the ligand, such as hexane, heptane, octane, chloroform, toluene, benzene, etc.

[0126] The above quantum dots may be non-dispersible or insoluble with respect to water, the aforementioned non-solvent, or a combination thereof. The above quantum dots may be dispersed in the aforementioned organic solvent. In one embodiment, the above quantum dots may be dispersed in C6 to C40 aliphatic hydrocarbons, C6 to C40 substituted or unsubstituted aromatic hydrocarbons, or a combination thereof.

[0127] The above-described electroluminescent display device may include a charge (hole or electron) auxiliary layer between a first electrode and a second electrode (e.g., an anode and a cathode). For example, the above-described electroluminescent display device may include a hole auxiliary layer (20) or an electron auxiliary layer (40) between the anode (10) and the quantum dot emitting layer (30) and / or between the cathode (50) and the quantum dot emitting layer (30). (See FIG. 1 and FIG. 2)

[0128] A light-emitting element according to one embodiment may further include a hole assist layer. The hole assist layer (12) is located between the first electrode (11) and the light-emitting layer (13). The hole assist layer (12) may include a hole injection layer, a hole transport layer, and / or an electron (or hole) blocking layer. The hole assist layer (12) may be a single-component layer or a multilayer structure in which adjacent layers include different components.

[0129] The HOMO energy level of the hole assist layer (12) may have a HOMO energy level that can be matched with the HOMO energy level of the light-emitting layer (13) to enhance the mobility of holes transferred from the hole assist layer (12) to the light-emitting layer (13). In one embodiment, the hole assist layer (12) may include a hole injection layer located close to the first electrode (11) and a hole transport layer located close to the light-emitting layer (13).

[0130] The material included in the hole assist layer (12) (e.g., hole transport layer, hole injection layer, or electron blocking layer) is not particularly limited and, for example, poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (Poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine), TFB), polyarylamine, poly(N-vinylcarbazole), poly(3,4-ethylenedioxythiophene), PEDOT, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), m-MTDATA (4,4',4"-Tris[phenyl(m-tolyl)amino]triphenylamine), 4,4',4"-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-toylamino)phenylcyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO3, MoO3, etc.), carbon-based materials such as graphene oxide It may include at least one selected from combinations thereof, but is not limited thereto.

[0131] In the hole assist layer(s), the thickness of each layer can be appropriately selected. For example, the thickness of each layer may be 5 nm or more, 10 nm or more, 15 nm or more, or 20 nm or more and 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, e.g., 40 nm or less, 35 nm or less, or 30 nm or less, but is not limited thereto.

[0132] The electronic auxiliary layer (14) is located between the light-emitting layer (13) and the second electrode (15). The electronic auxiliary layer (14) may include, for example, an electron injection layer, an electron transport layer, and / or a hole (or electron) blocking layer. The electronic auxiliary layer may include, for example, an electron injection layer (EIL) that facilitates the injection of electrons, an electron transport layer (ETL) that facilitates the transport of electrons, a hole blocking layer (HBL) that prevents the movement of holes, or a combination thereof.

[0133] In one embodiment, an electron injection layer may be disposed between the electron transport layer and the cathode. For example, a hole blocking layer may be disposed between the emitting layer and the electron transport (injection) layer, but is not limited thereto. The thickness of each layer may be appropriately selected. For example, the thickness of each layer may be 1 nm or more and 500 nm or less, but is not limited thereto. The electron injection layer may be an organic layer formed by deposition. The electron transport layer may contain inorganic oxide nanoparticles or may be an organic layer formed by deposition.

[0134] The electron transport layer (ETL) and / or electron injection layer and / or hole blocking layer may comprise, for example, at least one selected from 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-methyl]borane (3TPYMB), LiF, Alq3, Gaq3, Inq3, Znq2, Zn(BTZ)2, BeBq2, ET204 (8-(4-(4,6-di(naphthalen-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone), 8-hydroxyquinolinato lithium (Liq), n-type metal oxides (e.g., ZnO, HfO2, etc.) and combinations thereof, but is not limited thereto.

[0135] The electronic auxiliary layer (14) may include an electron transport layer. The electron transport layer may include a plurality of nanoparticles.

[0136] The above nanoparticles may include a metal oxide containing zinc.

[0137] The metal oxide may include zinc oxide, zinc magnesium oxide, or a combination thereof. The metal oxide is Zn 1-x M x O (wherein M is Mg, Ca, Zr, W, Li, Ti, Y, Al, or a combination thereof, and 0 ≤ x ≤ 0.5) may be included. In one embodiment, M in Formula 1 may be magnesium (Mg). In one embodiment, x in Formula 1 may be 0.01 or more and 0.3 or less, e.g., 0.25 or less, 0.2 or less, or 0.15 or less.

[0138] The absolute value of the LUMO of the aforementioned quantum dots included in the light-emitting layer may be greater or smaller than the absolute value of the LUMO of the metal oxide. The average size of the nanoparticles may be 1 nm or more, for example, 1.5 nm or more, 2 nm or more, 2.5 nm or more, or 3 nm or more and 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, or 5 nm or less.

[0139] In one embodiment, the thickness of each of the electron auxiliary layer (14) (e.g., electron injection layer, electron transport layer, or hole blocking layer) may be 5 nm or more, 6 nm or more, 7 nm or more, 8 nm or more, 9 nm or more, 10 nm or more, 11 nm or more, 12 nm or more, 13 nm or more, 14 nm or more, 15 nm or more, 16 nm or more, 17 nm or more, 18 nm or more, 19 nm or more, or 20 nm or more, and 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, or 25 nm or less, but is not limited thereto.

[0140] A device according to one embodiment may have a normal structure. In one embodiment, the device may have an anode (10) disposed on a transparent substrate (100) that may include a metal oxide-based transparent electrode (e.g., an ITO electrode), and a cathode (50) facing the anode that may include a conductive metal (e.g., Mg, Al, etc.) having a relatively low work function. A hole assist layer (20) (e.g., a hole injection layer such as PEDOT:PSS and / or p-type metal oxide and / or a hole transport layer such as TFB and / or PVK) may be disposed between the transparent electrode (10) and the light-emitting layer (30). The hole injection layer may be disposed close to the transparent electrode, and the hole transport layer may be disposed close to the light-emitting layer. An electron assist layer (40), such as an electron injection layer / transport layer, may be disposed between the quantum dot light-emitting layer (30) and the cathode (50). (See FIG. 1)

[0141] The device of another embodiment may have an inverted structure. Here, a cathode (50) disposed on a transparent substrate (100) may comprise a metal oxide-based transparent electrode (e.g., ITO), and an anode (10) facing the cathode may comprise a metal (e.g., Au, Ag, etc.) having a relatively high work function. For example, an n-type metal oxide (crystalline Zn metal oxide, etc., optionally doped) may be disposed between the transparent electrode (50) and the light-emitting layer (30) as an electron auxiliary layer (e.g., electron transport layer) (40). Between the metal anode (10) and the quantum dot light-emitting layer (30), MoO3 or another p-type metal oxide may be disposed as a hole auxiliary layer (e.g., a hole transport layer including TFB and / or PVK and / or a hole injection layer including MoO3 or another p-type metal oxide) (20). (See FIG. 2)

[0142] The aforementioned device can be manufactured by a suitable method. For example, the electroluminescent device can be manufactured by optionally forming a hole-assist layer (e.g., by deposition or coating) on ​​a substrate on which an electrode is formed, forming a light-emitting layer containing quantum dots (e.g., a pattern of the aforementioned quantum dots), and forming (an electron-assist layer and, optionally) and an electrode (e.g., by deposition or coating) on ​​the light-emitting layer. The method of forming the electrode / hole-assist layer / electron-assist layer can be appropriately selected and is not particularly limited.

[0143] In a display device of one embodiment, the (blue or green) quantum dot emitting layer may have a maximum external quantum efficiency (EQE) of 7% or more, 7.5% or more, 7.7% or more, 8% or more, 8.5% or more, 9% or more, 9.6% or more, 9.7% or more, or 10% or more. The display device of one embodiment may display increased brightness by including the aforementioned mixed emitting layer.

[0144] In one embodiment, the display device has a maximum brightness of a green pixel (light) of 100,000 cd / m² 2 Above, 110,000 cd / m 2 Above, 120,000 cd / m 2 Above, 130,000 cd / m 2 Above, 140,000 cd / m 2 Above, 150,000 cd / m 2 Above, 160,000 cd / m 2 Above, or 170,000 cd / m 2 It could be more than that.

[0145] The above device has a maximum luminance of 30,000 cd / m² of blue pixel (light). 2 Above, 31,000 cd / m 2 Above, 32,000 cd / m 2 Above, 33,000 cd / m 2 Above, 34,000 cd / m 2 Above, 35,000 cd / m 2Above, 36,000 cd / m 2 Above, 37,000 cd / m 2 Above, 38,000 cd / m 2 Above, 39,000 cd / m 2 Above, 40,000 cd / m 2 Above, 44,000 cd / m 2 Above, 50,000 cd / m 2 Above, or 52,000 cd / m 2 It could be more than that.

[0146] Specific embodiments are presented below. However, the embodiments described below are merely for the purpose of specifically illustrating or explaining the invention and should not limit the scope of the invention.

[0147] [Example]

[0148] Analysis method

[0149] [1] Photoluminescence analysis

[0150] Hitachi F-7000 A photoluminescence (PL) spectrum of a quantum dot prepared at a predetermined irradiation wavelength (e.g., 372 nm) is obtained using a spectrophotometer.

[0151] [2] Electroluminescence Spectroscopic Analysis

[0152] While applying voltage, the current corresponding to the voltage is measured using a Keithley 2635B source meter, and the EL luminescence brightness is measured using a CS2000 spectrometer.

[0153] Synthesis is performed in an inert gas atmosphere (under nitrogen-flowing conditions) unless otherwise specified. Precursor content is molar unless otherwise specified.

[0154] Synthesis Example 1:

[0155] [1] Manufacture of ZnSe or ZnTeSe cores

[0156] Selenium and tellurium are dispersed in trioctylphosphine (TOP) to obtain a 2M Se / TOP stock solution and a 0.1M Te / TOP stock solution.

[0157] 0.125 mmol of zinc acetate is added to a reactor along with 0.25 mmol of oleic acid and 0.25 mmol of hexadecylamine, and 10 mL of trioctylamine is heated to 120°C under vacuum. After 1 hour, the atmosphere inside the reactor is switched to nitrogen.

[0158] After heating to 300°C, the Se / TOP stock solution and Te / TOP stock solution prepared above are rapidly injected at a predetermined Te / Se molar ratio (0, 1 / 33, 1 / 20, 1 / 15).

[0159] [2] ZnSeS / ZnS multilayer shell formation

[0160] 1.8 mmol (0.336 g) of zinc acetate, 3.6 mmol (1.134 g) of oleic acid, and 10 mL of trioctylamine are placed in a flask and vacuumed at 120°C for 10 minutes. After purging the inside of the flask with nitrogen (N2), the temperature is raised to 180°C. Thereupon, the core prepared above is placed within 10 seconds, followed by the slow injection of a predetermined amount of Se / TOP together with zinc oleate, and then the temperature is raised to 280°C. Afterward, a predetermined amount of S / TOP together with zinc oleate is added, and the temperature is raised to 320°C and reacted for 10 minutes. Subsequently, a predetermined amount of Se / TOP and a predetermined amount of S / TOP together with zinc oleate are slowly injected, and the reaction is carried out again for 20 minutes.

[0161] After the above reaction is finished, the reactor is cooled, and the prepared nanocrystals are centrifuged with ethanol and dispersed in toluene.

[0162] Photoluminescence analysis of the manufactured quantum dots was performed, and the results are shown in Figure 4.

[0163] From Figure 4, it is confirmed that the wavelength can be controlled as the Te content increases, but the full width at half maximum of the emission peak increases significantly and the emission in the long wavelength region increases.

[0164] Experimental Example 1:

[0165] The color coordinates that can be realized by the four types of blue quantum dots prepared in Synthesis Example 1 are calculated from the emission spectrum and summarized in Table 1 below. From the results in Table 1 below, it is confirmed that the four types of synthesized blue quantum dots differ from the DCI blue emission source color coordinates Cx 0.15 and Cy 0.06, and that there is a limit to color expression in adjusting the color coordinates by increasing the Te content.

[0166] Te ratio (Te / Se) 0% 1 / 33 1 / 20 1 / 15 Cx 0.159 0.15 0.14 0.132 Cy 0.018 0.046 0.075 0.101

[0167] Experimental Example 2: For a light-emitting layer composed of blue quantum dots (Te 0 and Te 1 / 15) prepared in Synthesis Example 1 and a light-emitting layer prepared by mixing Te-free quantum dots with green light-emitting quantum dots (light-emitting wavelength: 545 nm), optical properties and relative color reproduction rates were obtained by simulation from the light-emitting spectrum, and the results are summarized in Table 2 below.

[0168] composition of the light-emitting layer Relative luminance Cx Cy Relative color reproduction rate Te free (Te 0) 58% 0.150 0.046 0% Te 1 / 15 100% 0.132 0.101 -14% Te-free 91% + green QD 9% 102% 0.158 0.080 -3.7%

[0169] From the results in Table 2 below, it is confirmed that mixing with green emitting quantum dots can increase the degree of freedom for color coordinate adjustment and lead to an improvement in brightness.

[0170] Experimental Example 3:

[0171] A quantum dot solution prepared by dispersing the blue quantum dots (Te 1 / 33 and Te 1 / 20) prepared in Synthesis Example 1 in octane, and a quantum dot solution prepared by mixing the blue quantum dots (Te 1 / 33) prepared in Synthesis Example 1 with 1 wt%, 3 wt%, 5 wt%, or 7 wt% of the green light-emitting quantum dots (QG) prepared in Synthesis Example 2 and dispersing them in octane, are each prepared, and an electroluminescent device is fabricated using these solutions according to the method below:

[0172] PEDOT:PSS and TFB (or PVK) layers are formed as hole-assisted layers on a glass substrate on which an ITO electrode (anode) is deposited by a spin coating method. A quantum dot emitting layer is formed by spin coating a quantum dot solution onto the formed TFB (or PVK) layer. A ZnO nanoparticle layer is formed as the electron-assisted layer on the quantum dot emitting layer, and subsequently, an Al electrode is formed by deposition.

[0173] The luminescence properties are measured while applying a voltage (0~7V) between the ITO electrode and the Al electrode. The measured electroluminescence properties are summarized in Table 6 and Figure 5 below.

[0174] EQE (max) Luminance Max(cd / m 2 ) Te 1 / 33 only 9.6% 35,400 Te 1 / 33 + QG 1% 9.8% 44,600 Te 1 / 33 + QG 3% 10.2% 53,000 Te 1 / 33 + QG 5% 9.9% 68,500 Te 1 / 33 + QG 7% 9.3% 80,900

[0175] From the results of Figure 5, it is confirmed that in the case of a blue light-emitting layer mixed with green light-emitting quantum dots (QG), both a blue light-emitting peak and a green light-emitting peak can be exhibited upon voltage application. From the results of Table 7, it is confirmed that in the case of a blue light-emitting layer mixed with green light-emitting quantum dots, enhanced brightness can be exhibited.

[0176] As a result of measuring the color coordinates of the fabricated emissive layer, it is confirmed that Cx and Cy can be adjusted by the introduction of green emissive quantum dots.

[0177] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

Claim 1 An electroluminescent (EL) display device comprising a red pixel, a green pixel, and a blue pixel, wherein the device comprises: a first electrode and a second electrode facing each other; and a quantum dot emitting layer disposed between the first electrode and the second electrode and not containing cadmium, wherein the quantum dot emitting layer comprises a red emitting layer disposed within the red pixel and comprising a plurality of red emitting quantum dots, a green emitting layer disposed within the green pixel and comprising a plurality of green emitting quantum dots, and a blue emitting layer disposed within the blue pixel and comprising blue emitting quantum dots, wherein the blue emitting layer is configured to exhibit a blue light emission peak and a first emitting peak different from the blue light emission peak when a voltage is applied, and the first wavelength difference between the blue light emission peak and the first emitting peak is greater than 30 nm and less than or equal to 150 nm. Claim 2 An electroluminescent display device according to claim 1, wherein the first wavelength difference is 35 nm or more and 80 nm or less. Claim 3 In claim 1, the electroluminescent display device wherein the first emission peak exists in a wavelength region longer than the blue light emission peak. Claim 4 An electroluminescent display device according to claim 1, wherein the green light-emitting layer is configured to exhibit a green light emission peak and a second light-emitting peak different from the green light emission peak when voltage is applied, and the second wavelength difference between the green light emission peak and the second light-emitting peak is 10 nm or more and 150 nm or less. Claim 5 An electroluminescent display device according to claim 4, wherein the second wavelength difference is 15 nm or more and 50 nm or less, or the second emission peak exists in a wavelength region shorter than the green light emission peak. Claim 6 An electroluminescent display device according to claim 1, wherein the ratio of the intensity of the first emission peak to the blue light emission peak is 0.05 or more and 0.6 or less. Claim 7 An electroluminescent display device according to claim 1, wherein the blue light-emitting layer exhibits a Cx value of 0.14 or higher and 0.18 or lower in CIE color coordinates, or wherein the blue light-emitting layer exhibits a Cy value of 0.06 or higher and 0.11 or lower in CIE color coordinates. Claim 8 In claim 1, the blue light-emitting layer has a maximum brightness of 36,000 cd / m² 2 An electroluminescent display device configured to display an ideal. Claim 9 In claim 1, the green light-emitting layer has a maximum brightness of 100,000 cd / m² 2 An electroluminescent display device configured to display an ideal. Claim 10 An electroluminescent display device according to claim 1, wherein the blue light-emitting layer is configured to emit light of the first light-emitting peak and further comprises a plurality of first quantum dots having a composition different from that of the blue light-emitting quantum dots. Claim 11 In claim 10, the blue light-emitting quantum dots are an electroluminescent display device comprising a zinc chalcogenide containing tellurium. Claim 12 In claim 10, the plurality of first quantum dots are a Group III-V compound comprising indium, phosphorus, and optionally zinc, zinc selenide telluride (ZnTe y Se 1-y ) (where y is 0.3 or more and 0.9 or less), zinc telluride, or a combination thereof, an electroluminescent display device. Claim 13 An electroluminescent display device according to claim 10, wherein in the blue light-emitting layer, the content of the plurality of first quantum dots is 0.1 weight% or more and 10 weight% or less based on the total weight of the blue light-emitting quantum dots. Claim 14 An electroluminescent display device according to claim 10, wherein in the blue light-emitting layer, the content of the plurality of first quantum dots is 1 weight% or more and 7 weight% or less based on the total weight of the blue light-emitting quantum dots. Claim 15 In claim 10, the above-mentioned blue-emitting quantum dots and the above-mentioned plurality of first quantum dots are mixed within the above-mentioned blue-emitting layer in an electroluminescent display device. Claim 16 In claim 4, the above-mentioned green light-emitting layer is configured to emit light of the second light-emitting peak and further comprises a plurality of second quantum dots having a composition different from that of the green light-emitting quantum dots. Claim 17 In claim 16, the green light-emitting quantum dot comprises a Group III-V compound containing indium, phosphorus, and optionally zinc, zinc selenide telluride, zinc telluride, or a combination thereof, in an electroluminescent display device. Claim 18 An electroluminescent display device according to claim 16, wherein in the green light-emitting layer, the content of the plurality of second quantum dots is 0.1 weight% or more and 10 weight% or less based on the total weight of the blue light-emitting quantum dots. Claim 19 An electroluminescent display device according to claim 1, wherein the ratio of the intensity of the first emission peak to the blue light emission peak is 0.1 or more and 0.5 or less.

Images