Quantum dot devices and electronic devices

Abstract

A quantum dot device and an electronic device are disclosed, wherein the quantum dot device includes an anode and a cathode facing each other, a quantum dot layer disposed between the anode and the cathode, and an electron transport layer disposed between the cathode and the quantum dot layer, wherein the quantum dot layer includes emitting quantum dots that emit light in at least a portion of a wavelength region in a visible region and non-emitting quantum dots that do not emit in the visible region, and the difference between the LUMO energy levels of the non-emitting quantum dots and the electron transport layer is greater than or equal to about 0.5 eV.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0028284 filed on March 9, 2018, in the Korean Intellectual Property Office, and Korean Patent Application No. 10-2019-0025444 filed on March 5, 2019, in the Korean Intellectual Property Office, the contents of which are incorporated herein in their entirety by reference. Technical Field

[0003] Quantum dot devices and electronic apparatus are disclosed. Background Art

[0004] Unlike bulk materials, the physical properties of nanoparticles (e.g., band gap, melting point, etc.) can be controlled by changing their particle size, which is an intrinsic property. For example, semiconductor nanocrystals, also called quantum dots, are provided with light or electrical energy, and they can emit light of a wavelength corresponding to the size of the quantum dots. Therefore, quantum dots can be used as light-emitting elements that emit light of a specific wavelength.

[0005] Quantum dot devices including quantum dots can be used as light-emitting elements. However, quantum dots are different from conventional light-emitting elements, and thus new methods for improving the performance of quantum dot devices are needed. Summary of the invention

[0006] One embodiment provides a quantum dot device capable of achieving improved performance.

[0007] Another embodiment provides an electronic device including the quantum dot device.

[0008] According to one embodiment, a quantum dot device includes an anode and a cathode facing each other, a quantum dot layer disposed between the anode and the cathode, and an electron transport layer disposed between the cathode and the quantum dot layer, wherein the quantum dot layer includes emitting quantum dots that emit light in at least a portion of a wavelength range in the visible (light) region and non-emitting quantum dots that are configured not to emit light in the visible region, and the difference between the LUMO energy level of the non-emitting quantum dots and the LUMO energy level of the electron transport layer is greater than or equal to about 0.5 eV.

[0009] The LUMO energy level of the non-emissive quantum dots may be about 0.5 eV or more less than the LUMO energy level of the electron transport layer.

[0010] The LUMO energy level of the non-emissive quantum dots may be about 0.5 eV to about 1.5 eV less than the LUMO energy level of the electron transport layer.

[0011] The energy band gap of the non-emissive quantum dots may be larger than the energy band gap of the emissive quantum dots.

[0012] The energy band gap of the non-emissive quantum dots may be greater than or equal to about 3.0 eV.

[0013] The LUMO energy level of the non-emissive quantum dot may be lower than the LUMO energy level of the emissive quantum dot and the LUMO energy level of the electron transport layer, respectively.

[0014] The diameter of the non-emissive quantum dots may be smaller than the diameter of the emitting quantum dots.

[0015] The quantum dot layer may include a mixture of emissive and non-emissive quantum dots.

[0016] Non-emissive quantum dots may be included in smaller amounts than emissive quantum dots.

[0017] The non-emissive quantum dots may be included in an amount less than or equal to about 20 wt % based on the total amount of the emitting quantum dots and the non-emissive quantum dots.

[0018] The quantum dot layer may include: a first quantum dot layer including emitting quantum dots; and a second quantum dot layer including non-emitting quantum dots.

[0019] The second quantum dot layer may be thinner than the first quantum dot layer.

[0020] The thickness of the second quantum dot layer may be less than or equal to about 20 nm.

[0021] The first quantum dot layer may be closer to the electron transport layer than the second quantum dot layer.

[0022] The HOMO energy level of the emitting quantum dots may be from about 5.3 eV to about 7.5 eV.

[0023] The emissive quantum dots may be quantum dots having a core-shell structure, and the non-emissive quantum dots may be quantum dots having a core structure without a shell.

[0024] The core of the emissive quantum dot may include zinc (Zn), tellurium (Te), and selenium (Se), and the shell of the emissive quantum dot may include ZnSeS, ZnS, or a combination thereof.

[0025] The non-emissive quantum dots may include ZnS, ZnSe, ZnTe, CdS, or a combination thereof.

[0026] The quantum dot device may further include a hole transport layer disposed between the anode and the quantum dot layer, and the HOMO energy level of the hole transport layer may be about 5.2 eV to about 7.3 eV.

[0027] According to another embodiment, an electronic device includes the quantum dot device.

[0028] The performance of the quantum dot device can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic cross-sectional view of a quantum dot device according to one embodiment,

[0030] Figure 2A and 2B yes Figure 1 Schematic diagram of a quantum dot device including emitting quantum dots and non-emitting quantum dots in a quantum dot layer,

[0031] Figure 3 Yes Description Figure 1 Energy diagram of an example performance level of a quantum dot device,

[0032] Figure 4 is a cross-sectional view schematically showing a quantum dot device according to another embodiment, and

[0033] Figure 5 It is shown Figure 4 Energy diagram of an example performance level of a quantum dot device. DETAILED DESCRIPTION

[0034] Hereinafter, example embodiments of the present disclosure will be described in detail so that those skilled in the art can understand the present disclosure. However, the present disclosure can be embodied in many different forms and is not to be construed as limited to the example embodiments described herein.

[0035] In the accompanying drawings, the thickness of layers, films, panels, regions, etc. is exaggerated for clarity. In the specification, the same reference numerals always represent the same elements. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it may be directly on the other element or there may be an intermediate element. On the contrary, when an element is referred to as being "directly on" another element, there is no intermediate element.

[0036] Hereinafter, the work function (WF), HOMO energy level and LUMO energy level are expressed as absolute values ​​from the vacuum energy level. In addition, when the work function, HOMO energy level or LUMO energy level is referred to as deep, high or large, the work function, HOMO energy level or LUMO energy level has a large absolute value based on the vacuum energy level of "0 eV", and when the work function, HOMO energy level or LUMO energy level is referred to as shallow, low or small, the work function, HOMO energy level or LUMO energy level has a small absolute value based on the vacuum energy level of "0 eV".

[0037] Hereinafter, a quantum dot device according to an embodiment is described with reference to the accompanying drawings.

[0038] Figure 1 FIG. 2 is a schematic cross-sectional view of a quantum dot device according to one embodiment; FIG. Figure 1A schematic diagram of an emitting quantum dot and a non-emitting quantum dot included in a quantum dot layer of a quantum dot device, and Figure 3 Yes Description Figure 1 Energy diagram of an example performance level of a quantum dot device.

[0039] refer to Figure 1 According to one embodiment, a quantum dot device 10 includes an anode 11 and a cathode 12 facing each other, and an electron transport layer 13, a quantum dot layer 14, a hole transport layer 15 and a hole injection layer 16 disposed between the anode 11 and the cathode 12.

[0040] A substrate (not shown) may be provided on one side of the anode 11 or the cathode 12. The substrate may be made of, for example, an inorganic material such as glass; an organic material such as polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyethersulfone, or a combination thereof; or a silicon wafer.

[0041] The anode 11 may be made of a conductor having a relatively large work function to facilitate hole injection, and may be made of, for example, a metal, a metal oxide, and / or a conductive polymer. The anode 11 may be made of, for example, a metal or an alloy thereof such as nickel, platinum, vanadium, chromium, copper, zinc, and gold; a conductive metal oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO), or fluorine-doped tin oxide; or a combination of a metal and an oxide such as ZnO and Al or SnO 2 and Sb, but not limited thereto.

[0042] The cathode 12 may be made of a conductor having a small work function to facilitate electron injection, and may be made of, for example, a metal, a metal oxide, and / or a conductive polymer. The cathode 12 may be, for example, a metal such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, lead, cesium, barium, etc., or an alloy thereof; a multilayer structure material such as LiF / Al, LiO 2 / Al, LiF / Ca, Liq / Al and BaF 2 / Ca, but not limited thereto.

[0043] At least one of the anode 11 and the cathode 12 may be a light-transmitting electrode, and the light-transmitting electrode may be made of, for example, a conductive oxide such as zinc oxide, indium oxide, tin oxide, indium tin oxide (ITO), indium zinc oxide (IZO) or fluorine-doped tin oxide, or a single or multiple metal thin layer. When one of the anode 11 and the cathode 12 is a non-light-transmitting electrode, it may be made of, for example, an opaque conductor such as aluminum (Al), silver (Ag) or gold (Au).

[0044] The electron transport layer 13 may be disposed on one surface of the cathode 12, and may include one layer or two or more layers. The electron transport layer 13 may include, for example, an inorganic material, an organic material, and / or an organic / inorganic material.

[0045] The LUMO energy level (LUMO ETL ) may be equal to or less than the work function (WF c ). The LUMO energy level of the electron transport layer 13 (LUMO ETL ) and the work function (WF c ) may be less than or equal to about 0.5 eV. For example, the LUMO energy level (LUMO ETL ) may be from about 2.5 eV to about 4.3 eV, for example, from about 2.7 eV to about 4.0 eV, or from about 2.7 eV to about 3.8 eV.

[0046] The electron transport layer 13 may include, for example, at least one of the following: 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproin (BCP), tris[3-(3-pyridyl)-2,4,6-trimethylphenyl]borane (3TPYMB), LiF, Alq 3 , Gaq 3 、Inq 3 、Znq 2 、Zn(BTZ) 2 、BeBq 2 , ET204 (8-(4-(4,6-di(naphthalene-2-yl)-1,3,5-triazine-2-yl)phenyl)quinolone), 8-hydroxyquinoline lithium (Liq), n-type metal oxides (such as ZnO, HfO 2 etc.), and combinations thereof, but are not limited thereto.

[0047] The quantum dot layer 14 includes emitting quantum dots 14a and non-emitting quantum dots 14b. For example, the emitting quantum dots 14a and non-emitting quantum dots 14b may exist in the quantum dot layer 14 in the form of a mixture.

[0048] The emitting quantum dot 14a may be a quantum dot that emits light in at least a portion of the wavelength range in the visible region, such as a quantum dot that emits blue light, red light, or green light. Here, the blue light may have a peak emission wavelength (λ) of, for example, about 430 nm to about 470 nm. max ), the red light may have a peak emission wavelength (λ of, for example, about 620 nm to about 660 nm. max ), and the green light may have a peak emission wavelength (λ of, for example, about 510 nm to about 550 nm. max ). The emission wavelength of the emitting quantum dot 14a can be determined according to the size and / or composition.

[0049] The emission quantum dot 14a may have a relatively narrow half width (full width at half maximum) (FWHM). Here, FWHM is the wavelength width corresponding to half of the peak absorption point, and as the FWHM is narrower, light in a narrower wavelength region may be emitted and high color purity may be obtained. The quantum dots may have a FWHM of, for example, about 50 nm or less, about 49 nm or less, about 48 nm or less, about 47 nm or less, about 46 nm or less, about 45 nm or less, about 44 nm or less, about 43 nm or less, about 42 nm or less, about 41 nm or less, about 40 nm or less, about 39 nm or less, about 38 nm or less, about 37 nm or less, about 36 nm or less, about 35 nm or less, about 34 nm or less, about 33 nm or less, about 32 nm or less, about 31 nm or less, about 30 nm or less, about 29 nm or less, or about 28 nm or less.

[0050] The non-emissive quantum dots 14b may be quantum dots that do not emit light in the visible region. The non-emissive quantum dots 14b are not particularly limited with respect to light in the non-visible region, such as the infrared region and / or the ultraviolet (UV) region.

[0051] The emission quantum dots 14a and the non-emission quantum dots 14b may have a particle diameter (average maximum particle length for non-spherical shapes) of, for example, about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm to about 50 nm, about 1 nm to about 40 nm, about 1 nm to about 30 nm, or about 1 nm to about 20 nm. Here, the particle diameter of the non-emission quantum dots 14b may be smaller than the particle diameter of the emission quantum dots 14a, and for example, the particle diameter of the non-emission quantum dots 14b may be about 0.1 times to about 0.9 times, about 0.2 times to about 0.8 times, about 0.2 times to about 0.7 times, about 0.2 times to about 0.6 times, or about 0.2 times to about 0.5 times larger than the particle diameter of the emission quantum dots 14a.

[0052] The emission quantum dots 14a and the non-emission quantum dots 14b are semiconductor nanocrystals in the general concept and may have a variety of shapes, such as isotropic semiconductor nanocrystals, quantum rods or quantum plates. The emission quantum dots 14a and the non-emission quantum dots 14b may independently include, for example, II-VI semiconductor compounds, III-V semiconductor compounds, IV-VI semiconductor compounds, IV semiconductors, I-III-VI semiconductor compounds, I-II-IV-VI semiconductor compounds, II-III-V semiconductor compounds, or combinations thereof. The II-VI semiconductor compounds can be selected, for example, from the group consisting of: binary compounds selected from the group consisting of CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS and mixtures thereof; binary compounds selected from the group consisting of CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, Cd Ternary compounds selected from ZeSeSTe, HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe and mixtures thereof, but not limited thereto. The III-VI semiconductor compounds may, for example, be selected from: binary compounds selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb and mixtures thereof; ternary compounds selected from GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb and mixtures thereof; and quaternary compounds selected from GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb and mixtures thereof, but are not limited thereto.The IV-VI semiconductor compound may be selected, for example, from: a binary compound selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe and a mixture thereof; a ternary compound selected from SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe and a mixture thereof; and a quaternary compound selected from SnPbSSe, SnPbSeTe, SnPbSTe and a mixture thereof, but is not limited thereto. The IV semiconductor may be selected, for example, from: a mono-semiconductor selected from Si, Ge and a mixture thereof; and a binary semiconductor compound selected from SiC, SiGe and a mixture thereof, but is not limited thereto. The I-III-VI semiconductor compound may be selected, for example, from CuInSe. 2 、CuInS 2 , CuInGaSe, CuInGaS and mixtures thereof, but not limited thereto. The I-II-IV-VI semiconductor compound may be, for example, selected from CuZnSnSe, CuZnSnS and mixtures thereof, but not limited thereto. The I-III-V semiconductor compound may include, for example, InZnP, but not limited thereto.

[0053] The emitting quantum dots 14a and the non-emitting quantum dots 14b may independently include the mono-semiconductor, the binary semiconductor compound, the ternary semiconductor compound, or the quaternary semiconductor compound in a substantially uniform concentration distribution or in a partially different concentration distribution.

[0054] For example, the emitting quantum dots 14a and the non-emitting quantum dots 14b may include non-cadmium-based quantum dots. Cadmium (Cd) may cause serious environmental / health issues and is an element restricted by the Restriction of Hazardous Substances Directive (RoHS) in many countries, and therefore non-cadmium-based quantum dots may be effectively used.

[0055] For example, the emitting quantum dot 14a may have a core-shell structure including a core 14aa and a shell 14ab, such as Figure 2A As shown in . For example, the material composition of the shell 14ab of the emitting quantum dot 14a may have a higher energy band gap than the material composition of the core 14aa of the emitting quantum dot 14a. Therefore, a quantum confinement effect may be exhibited, and light may be emitted thereby. For example, the shell 14ab of the emitting quantum dot 14a may be a single layer or a multilayer. For example, the shell of the multilayer shell away from the core may have a higher energy band gap than the shell close to the core, and thereby the quantum dot may exhibit a quantum confinement effect. The material constituting the core 14aa of the emitting quantum dot 14a and the material constituting the shell 14ab may be different from each other, and may be selected from the above-mentioned semiconductor compounds respectively within the range capable of achieving the quantum confinement effect.

[0056] For example, the emission quantum dot 14a may include, for example, a core including a first semiconductor compound based on Zn-Te-Se including zinc (Zn), tellurium (Te) and selenium (Se) and a shell including a second semiconductor compound, the shell being disposed on at least a portion of the core and including a second semiconductor compound having a composition different from that of the core. The emission quantum dot 14a of the core-shell structure may emit blue light having a peak emission wavelength in a wavelength range of less than or equal to about 470 nm, for example, in a wavelength range of about 430 nm to about 470 nm.

[0057] The first Zn—Te—Se based semiconductor compound may be, for example, a Zn—Se based semiconductor compound including a small amount of tellurium (Te), and, for example, a Zn—Se based semiconductor compound composed of ZnTe. x Se 1-x A semiconductor compound represented by (wherein x is greater than approximately 0 and less than or equal to approximately 0.05).

[0058] For example, in a first semiconductor compound based on Zn-Te-Se, a molar amount of zinc (Zn) may be greater than a molar amount of selenium (Se), and a molar amount of selenium (Se) may be greater than a molar amount of tellurium (Te). For example, in the first semiconductor compound, a molar ratio of tellurium (Te) to selenium (Se) may be less than or equal to about 0.05, less than or equal to about 0.049, less than or equal to about 0.048, less than or equal to about 0.047, less than or equal to about 0.045, less than or equal to about 0.044, less than or equal to about 0.043, less than or equal to about 0.042, less than or equal to about 0.041, less than or equal to about 0.04, less than or equal to about 0.039, less than or equal to about 0.035, less than or equal to about 0.03, less than or equal to about 0.04 .... 29. less than or equal to about 0.025, less than or equal to about 0.024, less than or equal to about 0.023, less than or equal to about 0.022, less than or equal to about 0.021, less than or equal to about 0.02, less than or equal to about 0.019, less than or equal to about 0.018, less than or equal to about 0.017, less than or equal to about 0.016, less than or equal to about 0.015, less than or equal to about 0.014, less than or equal to about 0.013, less than or equal to about 0.012, less than or equal to about 0.011, or less than or equal to about 0.01. For example, in the first semiconductor compound, the molar ratio of tellurium (Te) to zinc (Zn) may be less than or equal to about 0.02, less than or equal to about 0.019, less than or equal to about 0.018, less than or equal to about 0.017, less than or equal to about 0.016, less than or equal to about 0.015, less than or equal to about 0.014, less than or equal to about 0.013, less than or equal to about 0.012, less than or equal to about 0.011, or less than or equal to about 0.01.

[0059] The second semiconductor compound may, for example, be selected from semiconductor compounds having a larger energy band gap than the first semiconductor compound, and may be, for example, a II-VI semiconductor compound, a III-V semiconductor compound, a IV-VI semiconductor compound, a IV semiconductor, an I-III-VI semiconductor compound, an I-II-IV-VI semiconductor compound, a II-III-V semiconductor compound, or a combination thereof that satisfies such an energy band gap. Examples of II-VI semiconductor compounds, III-V semiconductor compounds, IV-VI semiconductor compounds, IV semiconductors, I-III-VI semiconductor compounds, I-II-IV-VI semiconductor compounds, and II-III-V semiconductor compounds are the same as described above. For example, the second semiconductor compound may include zinc (Zn), selenium (Se) and / or sulfur (S). For example, the shell may include ZnSeS and / or ZnS. For example, the shell may have a concentration gradient of one component, and for example, the amount of sulfur (S) may increase as it moves away from the core.

[0060] For example, the emission quantum dot 14a may include, for example: a core including a third semiconductor compound based on In-Zn-P containing indium (In), zinc (Zn) and phosphorus (P), and a shell disposed on at least a portion of the core and including a fourth semiconductor compound having a different composition from the core. The emission quantum dot 14a having such a core-shell structure may emit blue light, green light, or red light. For example, the blue light may have a peak emission wavelength in a wavelength range of less than or equal to about 470 nm, for example, in a wavelength range of about 430 nm to about 470 nm.

[0061] In the third semiconductor compound based on In-Zn-P, a molar ratio of zinc (Zn) to indium (In) may be greater than or equal to about 25. For example, in the third semiconductor compound based on In-Zn-P, a molar ratio of zinc (Zn) to indium (In) may be greater than or equal to about 28, greater than or equal to about 29, or greater than or equal to about 30. For example, in the first semiconductor compound based on In-Zn-P, a molar ratio of zinc (Zn) to indium (In) may be less than or equal to about 55, for example, less than or equal to about 50, less than or equal to about 45, less than or equal to about 40, less than or equal to about 35, less than or equal to about 34, less than or equal to about 33, or less than or equal to about 32.

[0062] The fourth semiconductor compound may be, for example, selected from semiconductor compounds having a larger energy band gap than the third semiconductor compound, and may be, for example, a II-VI semiconductor compound, a III-V semiconductor compound, a IV-VI semiconductor compound, a IV semiconductor, an I-III-VI semiconductor compound, an I-II-IV-VI semiconductor compound, a II-III-V semiconductor compound, or a combination thereof that satisfies such an energy band gap. Examples of II-VI semiconductor compounds, III-V semiconductor compounds, IV-VI semiconductor compounds, IV semiconductors, I-III-VI semiconductor compounds, I-II-IV-VI semiconductor compounds, and II-III-V semiconductor compounds are the same as described above. For example, the fourth semiconductor compound may include zinc (Zn) and sulfur (S), and optionally selenium (Se). For example, the shell may include at least one inner shell disposed near the core and an outermost shell disposed at the outermost shell of the quantum dot, and at least one of the inner shell and the outermost shell may include a fourth semiconductor compound of ZnS or ZnSeS.

[0063] As an example, the non-emissive quantum dot 14b may have a core structure without a shell, such as Figure 2B As shown in . Therefore, the non-emitting quantum dot 14b may not emit light because it does not have the quantum confinement effect like the emitting quantum dot 14a. The non-emitting quantum dot 14b may be selected from the above-mentioned semiconductor compounds, and may include, for example, a II-VI semiconductor compound, a III-V semiconductor compound, a IV-VI semiconductor compound, a IV semiconductor, a I-III-VI semiconductor compound, a I-II-IV-VI semiconductor compound, a II-III-V semiconductor compound or a combination thereof, such as ZnS, ZnSe, ZnTe, CdS or a combination thereof.

[0064] The emitting quantum dots 14a and the non-emitting quantum dots 14b may have different energy levels, and for example, the energy band gap of the non-emitting quantum dots 14b may be greater than the energy band gap of the emitting quantum dots 14a. For example, the energy band gap of the non-emitting quantum dots 14b may be greater than or equal to about 3.0 eV, greater than or equal to about 3.1 eV, greater than or equal to about 3.2 eV, greater than or equal to about 3.4 eV, greater than or equal to about 3.6 eV, greater than or equal to about 3.8 eV, or greater than or equal to about 4.0 eV, and in the range of, for example, about 3.0 eV to about 5.5 eV, about 3.1 eV to about 5.5 eV, about 3.2 eV to about 5.5 eV, about 3.4 eV to about 5.5 eV, about 3.6 eV to about 5.5 eV, about 3.8 eV to about 5.5 eV, or about 4.0 eV to about 5.5 eV.

[0065] For example, the LUMO energy level (LUMO QD(14b)) can be smaller than the LUMO energy level (LUMO QD(14a) For example, the LUMO energy level (LUMO QD(14b) ) is comparable to the LUMO energy level of the emitting quantum dot 14a (LUMO QD(14a) ) is small: greater than or equal to about 0.2 eV, greater than or equal to about 0.4 eV, greater than or equal to about 0.5 eV, greater than or equal to about 0.7 eV, or greater than or equal to about 0.9 eV, and less than the LUMO energy level (LUMO QD(14a) ).

[0066] For example, the LUMO energy level (LUMO QD(14b) ) may be different from the LUMO energy level (LUMO ETL ), and the difference (Δd) between the LUMO energy levels of the non-emissive quantum dot 14b and the electron transport layer (ETL) 13 may be, for example, greater than or equal to about 0.5 eV. For example, the difference (Δd) between the LUMO energy levels of the non-emissive quantum dot 14b and the electron transport layer (ETL) 13 may be about 0.5 eV to about 1.5 eV. For example, the LUMO energy level (LUMO QD(14b) ) is comparable to the LUMO energy level of the electron transport layer 13 (LUMO ETL ) small: greater than or equal to about 0.5 eV, and for example, the LUMO energy level of the non-emissive quantum dot 14b may be smaller than the LUMO energy level of the electron transport layer 13 by about 0.5 eV to about 1.5 eV.

[0067] For example, the LUMO energy level (LUMO QD(14b) ) can be smaller than the LUMO energy level (LUMO QD(14a) ) and the LUMO energy level of the electron transport layer 13 (LUMO ETL For example, the LUMO energy level (LUMO QD(14b) ) is comparable to the LUMO energy level of the emitting quantum dot 14a (LUMO QD(14a) ) and the LUMO energy level of the electron transport layer 13 (LUMO ETL ) small: greater than or equal to about 0.5 eV. For example, the LUMO energy level (LUMO QD(14b) ) is comparable to the LUMO energy level of the emitting quantum dot 14a (LUMO QD(14a) ) and the LUMO energy level of the electron transport layer 13 (LUMOETL ) is about 0.5 eV to about 1.5 eV. Due to the low LUMO energy level of the non-emissive quantum dots 14b, the non-emissive quantum dots 14b act as a barrier (potential barrier) to electrons moving from the electron transport layer 13 to the quantum dot layer 14 to reduce electron mobility.

[0068] Typically, in a quantum dot device, the mobility of holes and electrons may be different, and, for example, the mobility of electrons may be higher than the mobility of holes. Therefore, a mobility imbalance may occur between holes moving from the anode 11 to the quantum dot layer 14 and electrons moving from the cathode 12 to the quantum dot layer 14, and therefore, electrons may not be coupled with holes at the emission position of the quantum dot layer 14 and uncoupled electrons may accumulate at the interface between the quantum dot layer 14 and the hole transport layer 15. As described above, the accumulated electrons at the interface between the quantum dot layer 14 and the hole transport layer 15 degrade the quantum dot device, thereby shortening the life of the quantum dot device.

[0069] In the present embodiment, non-emissive quantum dots 14b having a relatively low LUMO energy level may be included in the quantum dot layer 14, so that the mobility of electrons moving from the electron transport layer 13 to the quantum dot layer 14 may be controlled. Therefore, the mobility between holes moving from the anode 11 to the quantum dot layer 14 and electrons moving from the cathode 12 to the quantum dot layer 14 may be balanced to improve the luminous efficiency of the quantum dot device 10, and the accumulation of electrons at the interface between the quantum dot layer 14 and the hole transport layer 15 may be prevented, thereby improving the lifetime characteristics of the quantum dot device.

[0070] The HOMO energy level of the emitting quantum dot 14a (HOMO QD(14a) ) may be equal to or different from the HOMO energy level (HOMO QD(14b) ). The HOMO energy level of the emitting quantum dot 14a (HOMO QD(14a) ) and the HOMO energy level of the non-emissive quantum dot 14b (HOMO QD(14b) ) may be relatively high, and may be, for example, about 5.3 eV or more, about 5.4 eV or more, about 5.5 eV or more, about 5.6 eV or more, about 5.7 eV or more, about 5.8 eV or more, about 5.9 eV or more, or about 6.0 eV or more. The HOMO energy level (HOMO QD(14a) ) and the HOMO energy level of the non-emissive quantum dot 14b (HOMO QD(14b)) may be, for example, from about 5.3 eV to about 7.5 eV, from about 5.3 eV to about 7.2 eV, from about 5.4 eV to about 7.2 eV, from about 5.4 eV to about 7.0 eV, from about 5.6 eV to about 7.0 eV, from about 5.6 eV to about 6.8 eV, from about 5.6 eV to about 6.7 eV, from about 5.6 eV to about 6.5 eV, from about 5.6 eV to about 6.3 eV, from about 5.6 eV to about 6.2 eV, from about 5.6 eV to about 6.1 eV, from about 5.8 eV to about 7.0 eV V, about 5.8 eV to about 6.8 eV, about 5.8 eV to about 6.7 eV, about 5.8 eV to about 6.5 eV, about 5.8 eV to about 6.3 eV, about 5.8 eV to about 6.2 eV, about 5.8 eV to about 6.1 eV, about 6.0 eV to about 7.0 eV, about 6.0 eV to about 6.8 eV, about 6.0 eV to about 6.7 eV, about 6.0 eV to about 6.5 eV, about 6.0 eV to about 6.3 eV, or about 6.0 eV to about 6.2 eV.

[0071] As described above, the emitting quantum dots 14a and the non-emitting quantum dots 14b may be present in the form of a mixture in the quantum dot layer 14. In this case, the non-emitting quantum dots 14b may be included in a smaller amount than the emitting quantum dots 14a. For example, the non-emitting quantum dots 14b may be included in an amount less than about 50 wt%, such as less than or equal to about 40 wt%, less than or equal to about 30 wt%, or less than or equal to about 20 wt%, based on the total amount of the emitting quantum dots 14a and the non-emitting quantum dots 14b.

[0072] The quantum dot layer 14 may have a thickness of, for example, about 5 nm to 200 nm, about 10 nm to about 150 nm, about 10 nm to about 100 nm, about 15 nm to about 80 nm, about 20 nm to about 50 nm, or about 25 nm to about 40 nm.

[0073] The hole transport layer 15 and the hole injection layer 16 may be disposed between the anode 11 and the quantum dot layer 14, wherein the hole transport layer 15 is disposed on the quantum dot layer 14 side, and the hole injection layer 16 is disposed on the anode 11 side, and holes provided from the anode 11 may pass through the hole injection layer 16 and the hole transport layer 15 and be transmitted to the quantum dot layer 14. For example, the hole transport layer 15 may be in contact with the quantum dot layer 14, and the hole injection layer 16 may be in contact with the anode 11.

[0074] The HOMO energy level (HOMO HIL ) may be between the work function of the anode 11 and the HOMO energy level of the quantum dot layer 14, and may be, for example, about 5.0 eV to about 5.5 eV.

[0075] The hole injection layer 16 may include a conductive compound, such as a conductive metal oxide, a conductive monomer, a conductive oligomer, a conductive polymer, and / or a conductive ionic compound, for example, having a carbon content of greater than or equal to about 1×10 -7 S / cm conductive metal oxides, conductive monomers, conductive oligomers, conductive polymers and / or conductive ionic compounds, for example, having a conductivity of about 1x10 -7 Conductive metal oxides, conductive monomers, conductive oligomers, conductive polymers and / or conductive ionic compounds having a conductivity of about 1000 S / cm to about 1000 S / cm. The conductive compound may include, for example, polythiophene, polyaniline, polypyrrole, poly(p-phenylene), polyfluorene, poly(3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), derivatives thereof, or combinations thereof, but are not limited thereto.

[0076] The HOMO energy level (HOMO HTL ) can be at the HOMO level (HOMO HIL ) and the HOMO energy level (HOMO QD(14a) ). Therefore, a step-like energy level can be formed from the hole injection layer 16 to the quantum dot layer 14, and the hole mobility can be effectively increased.

[0077] The HOMO energy level (HOMO HTL ) may have a relatively high HOMO energy level like the quantum dot layer 14 to match the HOMO energy level (HOMO QD(14a) ).

[0078] For example, the HOMO level (HOMO HTL ) and the HOMO energy level (HOMO QD(14a) ) may be less than or equal to about 0.5 eV, such as about 0 eV to about 0.5 eV, about 0.01 eV to about 0.4 eV, about 0.01 eV to about 0.3 eV, about 0.01 eV to about 0.2 eV, or about 0.01 eV to about 0.1 eV. For example, the HOMO level (HOMO HTL ) may be equal to the HOMO energy level (HOMO QD(14a) ) or less than about 0.5 eV in the range of less than or equal to about 0.5 eV, less than the HOMO energy level (HOMO QD(14a) ).

[0079] For example, the HOMO level (HOMOHTL ) may be greater than or equal to about 5.2 eV, greater than or equal to about 5.4 eV, greater than or equal to about 5.6 eV, or greater than or equal to about 5.8 eV. For example, the HOMO energy level (HOMO HTL ) may be from about 5.2 eV to about 7.3 eV, from about 5.4 eV to about 7.3 eV, from about 5.4 eV to about 7.1 eV, from about 5.4 eV to about 7.0 eV, from about 5.4 eV to about 6.8 eV, from about 5.4 eV to about 6.7 eV, from about 5.4 eV to about 6.5 eV, from about 5.4 eV to about 6.3 eV, from about 5.4 eV to about 6.2 eV, from about 5.4 eV to about 6.1 eV, from about 5.6 eV to about 7.0 eV, from about 5.6 eV to about 6.8 eV , about 5.6eV to about 6.7eV, about 5.6eV to about 6.5eV, about 5.6eV to about 6.3eV, about 5.6eV to about 6.2eV, about 5.6eV to about 6.1eV, about 5.8eV to about 7.0eV, about 5.8eV to about 6.8eV, about 5.8eV to about 6.7eV, about 5.8eV to about 6.5eV, about 5.8eV to about 6.3eV, about 5.8eV to about 6.2eV, or about 5.8eV to about 6.1eV.

[0080] The hole transport layer 15 may not be particularly limited as long as the material satisfies the energy level, and may include, for example, a polymer selected from the following: poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), polyarylamine, poly(N-vinylcarbazole), polyaniline, polypyrrole, N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 4,4',4"-tri[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), 4,4',4"-tri(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC), p-type metal oxides (e.g., NiO, WO 3 or MoO 3 ), or carbon-based materials such as graphene oxide, but not limited thereto.

[0081] Figure 4 is a cross-sectional view schematically showing a quantum dot device according to another embodiment.

[0082] refer to Figure 4 Unlike the above-mentioned embodiment, the quantum dot device 10 according to the present embodiment includes an anode 11 and a cathode 12 facing each other, and an electron transport layer 13, a quantum dot layer 14, a hole transport layer 15, and a hole injection layer 16 arranged between the anode 11 and the cathode 12.

[0083] However, the quantum dot device according to the present embodiment is different from the above-mentioned embodiment in that the quantum dot layer 14 includes a first quantum dot layer 14-1 close to the electron transport layer 13 and including emitting quantum dots 14a and a second quantum dot layer 14-2 close to the hole transport layer 15 and including non-emitting quantum dots 14b.

[0084] The first quantum dot layer 14 - 1 may include the above-described emission quantum dots 14 a , and may include an emission site where holes supplied from the anode 11 and electrons supplied from the cathode 12 are combined to emit light.

[0085] The second quantum dot layer 14-2 may include non-emitting quantum dots 14b and does not include an emitting site. As described above, the LUMO energy level (LUMO QD(14b) ) is less than the LUMO energy level (LUMO QD(14a) ), and thus, the mobility of electrons can be reduced and / or blocked, so that the electrons passing through the first quantum dot 14-1 cannot flow into the hole transport layer 15. That is, the second quantum dot layer 14-2 acts as an electron blocking layer to prevent the accumulation of electrons at the interface between the quantum dot layer 14 and the hole transport layer 15, and thus the degradation of the quantum dot device can be reduced and / or prevented.

[0086] The second quantum dot layer 14-2 may be thinner than the first quantum dot layer 14-1. The thickness of the second quantum dot layer 14-2 may be less than or equal to about 20 nm, for example, about 1 nm to about 20 nm, about 1 nm to about 18 nm, about 1 nm to about 15 nm, about 1 nm to about 12 nm, about 1 nm to about 10 nm, but is not limited thereto.

[0087] The electron transport layer 13, quantum dot layer 14, hole transport layer 15 and hole injection layer 16 can be formed, for example, using a solution process or a deposition process, and the solution process can be, for example, spin coating, slit coating, inkjet printing, nozzle printing, spraying and / or doctor blade coating, but is not limited thereto.

[0088] The quantum dot device can be applied to various electronic devices, such as display devices or lighting devices.

[0089] Hereinafter, the embodiments are described in more detail with reference to Examples. However, these Examples are exemplary, and the present scope is not limited thereto.

[0090] Synthesis of quantum dots

[0091] Synthesis example 1

[0092] Step 1: Synthesis of ZnTeSe core

[0093] Selenium (Se) and tellurium (Te) were dispersed in trioctylphosphine (TOP) to obtain a 2M Se / TOP stock solution and a 0.1M Te / TOP stock solution.

[0094] 0.125 mmol of zinc acetate, 0.25 mmol of palmitic acid and 0.25 mmol of hexadecylamine were added to the reactor together with 10 mL of trioctylamine, and then heated under vacuum at 120° C. After 1 hour, the atmosphere in the reactor was switched to nitrogen.

[0095] After heating the reactor at 300° C., Se / TOP stock solution and Te / TOP stock solution were quickly added thereto at a Te / Se ratio of 1 / 25. After 10, 20 or 60 minutes, the reaction solution was quickly cooled to room temperature, acetone was added thereto, and the precipitate obtained by centrifuging the mixture was dispersed in toluene to obtain ZnTeSe quantum dots.

[0096] Step 2: Synthesis of ZnTeSe core / ZnSeS shell emissive quantum dots

[0097] 1.8 mmol (0.336 g) of zinc acetate, 3.6 mmol (1.134 g) of oleic acid and 10 mL of trioctylamine were added to the flask and vacuum was applied at 120° C. for 10 minutes. The flask was heated with nitrogen (N 2 ) replace the inside of the flask and heat at 180°C. The ZnTeSe core obtained in Synthesis Example 1 was placed therein within 10 seconds, and then 0.04mmol Se / TOP was slowly injected, and then heated at 280°C. Then, 0.01mmol S / TOP was added thereto and heated at 320°C and reacted for 10 minutes. Subsequently, a mixed solution of 0.02mmolSe / TOP and 0.04mmol S / TOP was slowly injected and reacted again for 20 minutes. Then, the following steps were repeated: Se and S were injected by changing their mixing ratio and reacted for 20 minutes. The mixed solution of Se and S used a mixed solution of 0.01mmol Se / TOP+0.05mmol S / TOP, a mixed solution of 0.005mmol Se / TOP+0.1mmol S / TOP, and a solution of 0.5mmolS / TOP in sequence. After completing all reactions, the reactor was cooled, the prepared nanocrystals were precipitated with ethanol, and the obtained nanocrystals were centrifuged and dispersed in toluene with ethanol to obtain ZnTeSe / ZnSeS core-shell emission quantum dots.

[0098] Synthesis Example 2: Preparation of ZnS Core Non-Emitting Quantum Dots

[0099] Sulfur (S) is dispersed in trioctylphosphine (TOP) to obtain 1M S / TOP stock solution. Diethyl zinc is dissolved in hexane to obtain 1M diethyl zinc stock solution. Organic ligands including oleic acid and diethyl zinc stock solution are dissolved in trioctylamine in a 300ml flask and heated at 120°C under vacuum. After the atmosphere in the flask is converted to an inert gas, the S / TOP stock solution is injected into the flask and heated to 300°C and reacted for 40 minutes. After the reaction, the reaction solution is quickly cooled to room temperature and ethanol is added thereto, and the precipitate obtained by centrifuging the mixture is dispersed in toluene to obtain ZnS non-emissive quantum dots. The molar ratio of Zn:S is approximately 2:1.

[0100] Fabrication of quantum dot devices I

[0101] Example 1

[0102] The glass substrates deposited with ITO (WF: 4.8 eV) were surface treated with UV-ozone for 15 min, spin-coated with PEDOT:PSS solution (HC Starks Co., Ltd.), and heat-treated at 150 °C for 10 min in air atmosphere, and then heated under N 2 The hole injection layer was then heat treated at 150° C. for 10 minutes under an atmosphere to form a 25 nm thick hole injection layer (HOMO: 5.3 eV, LUMO: 2.7 eV). Subsequently, a 25 nm thick hole transport layer (HOMO: 5.6 eV, LUMO: 2.7 eV) was formed on the hole injection layer by spin coating a hole transport material (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)], Sumitomo Chemical Co., Ltd.), and heat-treated it at 150°C for 30 minutes. Then, on the hole transport layer, a quantum dot layer (HOMO: 5.7 eV, LUMO: 3.0 eV) was formed by spin coating a solution of ZnTeSe / ZnSeS core / shell emitting quantum dots (peak emission wavelength: 453 nm) obtained in Synthesis Example 1 and ZnS core non-emitting quantum dots obtained in Synthesis Example 2 in a ratio of 95:5 (weight:weight), and heat-treated it at 150°C for 30 minutes. Then, on the quantum dot layer, a 40 nm thick electron transport layer (LUMO: 2.9 eV) was formed by vacuum depositing an electron transport material (a blended material of anthracene-based material and a pyrazole-based material, Novaled), and a cathode was formed thereon by vacuum depositing Liq to 5 nm and aluminum (Al) to 100 nm to manufacture a quantum dot device.

[0103] Example 2

[0104] A quantum dot device was fabricated in the same manner as Example 1, except that a quantum dot layer was formed using a solution including ZnTeSe / ZnSeS core / shell emitting quantum dots and ZnS core non-emitting quantum dots in a ratio of 80:20 (wt:wt).

[0105] Comparative Example 1

[0106] A quantum dot device was fabricated in the same manner as Example 1, except that the quantum dot layer included only ZnTeSe / ZnSeS core / shell emitting quantum dots, instead of a mixture of ZnTeSe / ZnSeS core / shell emitting quantum dots and ZnS core non-emitting quantum dots.

[0107] Evaluation I

[0108] The current-voltage-luminescence characteristics of the quantum dot devices according to Examples 1 and 2 and Comparative Example 1 were evaluated.

[0109] The current-voltage-luminescence characteristics were evaluated by using a Keithley 220 current source and a Minolta CS200 spectroradiometer.

[0110] The results are shown in Table 1.

[0111] [Table 1]

[0112]

[0113]

[0114] *EQE max : Maximum external quantum efficiency

[0115] *EQE@100 nits: External quantum efficiency at 100 nits

[0116] *EQE@500 nits: External quantum efficiency at 500 nits

[0117] *Cd / A max :Maximum current efficiency

[0118] *Cd / m 2 @5mA: Brightness at 5mA

[0119] Referring to Table 1, compared with the quantum dot device according to Comparative Example 1, the quantum dot devices according to Examples 1 and 2 showed improved luminous efficiency and brightness.

[0120] Fabrication of quantum dot devices II

[0121] Example 3

[0122] The glass substrates deposited with ITO (WF: 4.8 eV) were surface treated with UV-ozone for 15 min, spin-coated with PEDOT:PSS solution (HC Starks Co., Ltd.), and heat-treated at 150 °C for 10 min in air atmosphere, and then heated under N 2 The hole injection layer was then heat treated at 150° C. for 10 minutes under an atmosphere to form a 25 nm thick hole injection layer (HOMO: 5.3 eV, LUMO: 2.7 eV). Subsequently, a 25 nm thick hole transport layer (HOMO: 5.6 eV, LUMO: 2.7 eV) was formed on the hole injection layer by spin coating a hole transport material (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)], Sumitomo Chemical Co., Ltd.), and heat-treated it at 150°C for 30 minutes. Then, on the hole transport layer, a 5 nm thick lower quantum dot layer (HOMO: 6.3 eV, LUMO: 2.1 eV) was formed by spin coating the ZnS core non-emissive quantum dots obtained in Synthesis Example 2, and heat-treated it at 150°C for 30 minutes. Then, on the lower quantum dot layer, a 20 nm thick upper quantum dot layer (HOMO: 5.7 eV, LUMO: 3.0 eV) was formed by spin coating the ZnS core non-emissive quantum dots obtained in Synthesis Example 1. The obtained ZnTeSe / ZnSeS core / shell emission quantum dots (peak emission wavelength: 453 nm) were heat treated at 150°C for 30 minutes. Then, on the upper quantum dot layer, a 40 nm thick electron transport layer (LUMO: 2.9 eV) was formed by vacuum depositing an electron transport material (a blended material of anthracene-based material and pyrazole-based material, Novaled), and a cathode was formed thereon by vacuum depositing Liq to 5 nm and aluminum (Al) to 100 nm to manufacture a quantum dot device.

[0123] Comparative Example 2

[0124] A quantum dot device was manufactured in the same manner as in Example 3, except that the lower quantum dot layer was not formed.

[0125] Evaluation II

[0126] The current-voltage-luminescence characteristics of the quantum dot devices according to Example 3 and Comparative Example 2 were evaluated.

[0127] The results are shown in Table 2.

[0128] [Table 2]

[0129] Example 3 Comparative Example 2 <![CDATA[EQE max ]]> 4.3 2.7 EQE@100nits 4.3 2.7 EQE@500nits 3.6 2.5 <![CDATA[Cd / A max ]]> 3.1 2.1 <![CDATA[Cd / m 2 @5mA]]> 148.5 107.8 <![CDATA[λ max ]]> 457 457 Full width at half maximum (FWHM) (nm) 30 31 CIE x 0.1448 0.1450 CIE 0.0726 0.0825

[0130] Referring to Table 2, compared with the quantum dot device according to Comparative Example 2, the quantum dot device according to Example 3 exhibited improved luminous efficiency and brightness.

[0131] While the present disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it will be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. Quantum dot devices, including The anode and cathode face each other, a quantum dot layer disposed between the anode and the cathode, and An electron transport layer is disposed between the cathode and the quantum dot layer, wherein the quantum dot layer includes emitting quantum dots configured to emit light in at least a portion of a wavelength region in the visible region and non-emitting quantum dots configured not to emit light in the visible region, and The difference between the LUMO energy levels of the non-emissive quantum dots and the electron transport layer is greater than or equal to 0.5 eV, The LUMO energy level of the non-emitting quantum dots is respectively lower than the LUMO energy level of the emitting quantum dots and the LUMO energy level of the electron transport layer. 2 . The quantum dot device of claim 1 , wherein the LUMO energy level of the non-emissive quantum dot is 0.5 eV or more less than the LUMO energy level of the electron transport layer. 3 . The quantum dot device of claim 2 , wherein the LUMO energy level of the non-emissive quantum dots is 0.5 eV to 1.5 eV less than the LUMO energy level of the electron transport layer.

4. The quantum dot device of claim 1, wherein the non-emissive quantum dot has a greater energy band gap than the emissive quantum dot.

5. The quantum dot device of claim 1, wherein the non-emissive quantum dot has an energy band gap greater than or equal to 3.0 eV.

6. The quantum dot device of claim 1, wherein the diameter of the non-emitting quantum dot is smaller than the diameter of the emitting quantum dot.

7. The quantum dot device of claim 1, wherein the quantum dot layer comprises a mixture of the emitting quantum dots and the non-emitting quantum dots.

8. The quantum dot device of claim 7, wherein the non-emissive quantum dots are included in a lesser amount than the emissive quantum dots.

9. The quantum dot device of claim 7, wherein the non-emissive quantum dots are included in an amount less than or equal to 20 wt % based on the total amount of the emitting quantum dots and the non-emissive quantum dots.

10. The quantum dot device of claim 1, wherein the quantum dot layer comprises: a first quantum dot layer comprising said emitting quantum dots, and A second quantum dot layer includes the non-emissive quantum dots.

11. The quantum dot device of claim 10, wherein the second quantum dot layer is thinner than the first quantum dot layer.

12. The quantum dot device of claim 10, wherein the thickness of the second quantum dot layer is less than or equal to 20 nm.

13. The quantum dot device of claim 10, wherein the first quantum dot layer is closer to the electron transport layer than the second quantum dot layer.

14. The quantum dot device of claim 1, wherein the HOMO energy level of the emitting quantum dot is 5.3 eV to 7.5 eV.

15. The quantum dot device of claim 1, wherein the emitting quantum dot has a core-shell structure, and The non-emissive quantum dots have a core structure without a shell.

16. The quantum dot device of claim 15, wherein The core of the emitting quantum dot includes zinc (Zn), tellurium (Te) and selenium (Se), and The shell of the emitting quantum dot includes ZnSeS, ZnS or a combination thereof.

17. The quantum dot device of claim 15, wherein the non-emissive quantum dots comprise ZnS, ZnSe, ZnTe, CdS, or a combination thereof.

18. The quantum dot device of claim 1, further comprising a hole transport layer disposed between the anode and the quantum dot layer, and The HOMO energy level of the hole transport layer is 5.2 eV to 7.3 eV.

19. An electronic device comprising the quantum dot device according to any one of claims 1 to 18.

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