TW202036928A - Quantum dot light-emitting diodes comprising doped zno electron transport layer - Google Patents

Abstract

Articles and methods related to quantum dot light-emitting diodes are generally provided. A quantum dot light-emitting diode may comprise a first electrode, a quantum dot light-emitting layer disposed on the first electrode, an electron transport layer disposed on the quantum dot light-emitting layer, and second electrode disposed on the electron transport layer. The electron transport layer may comprise nanoparticles comprising ZnO doped with one or more dopants and/or capped with one or more ligands. The quantum dot light-emitting layer may comprise two or more electron transport layers, each of which may independently comprise ZnO doped with one or more dopants and/or capped with one or more ligands. The nanoparticles may have a number average diameter of less than or equal to 5 nm.

Description

Quantum dot light emitting diode containing doped ZnO electron transport layer

The present disclosure relates to quantum dot light-emitting diodes, and more specifically to the doped electron transport layer used for them.

The statements in this section only provide background information related to the present disclosure and may not constitute prior art.

Quantum dot light-emitting diodes can generate light after voltage is applied to them. Existing quantum dot light-emitting diodes usually emit light from quantum dots placed in a quantum dot light-emitting layer between two electrodes. The applied voltage allows electrons and holes to flow from these electrodes into the quantum dot layer, where the electrons and holes can be captured and recombined to generate photons. Some quantum dot light-emitting diodes further include an electron transport layer to help transport electrons from the cathode to the quantum dot light-emitting layer. However, the existing electron transport layer suffers from disadvantages such as an undesirably low work function, reducing the efficiency of electron transport. Therefore, an improved electron transport layer is needed.

Generally describe the doped ZnO electron transport layer, related components and related methods.

In some embodiments, quantum dot light emitting diodes are provided. The quantum dot light-emitting diode includes a first electrode, a quantum dot light-emitting layer arranged on the first electrode, an electron transfer layer arranged on the quantum dot light-emitting layer, and a second electrode arranged on the electron transfer layer. The electron transport layer includes nanoparticles, the nanoparticles include ZnO doped with one or more dopants, and the number average diameter of the nanoparticles is less than or equal to 5 nm.

In some embodiments, a method of manufacturing a quantum dot light-emitting diode is provided. The method includes assembling a first electrode of an electron transport layer, a second electrode, and a quantum dot light-emitting layer. The electron transport layer includes nanoparticles, the nanoparticles include ZnO doped with one or more dopants, and the number average diameter of the nanoparticles is less than or equal to 5 nm.

Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the present invention when considered in conjunction with the accompanying drawings. In the case of conflicting and/or inconsistent disclosure content in this specification and documents incorporated by reference, this specification shall prevail. If two or more documents incorporated by reference include conflicting and/or inconsistent disclosures relative to each other, the document with the later effective date shall prevail.

In the following description, reference is made to the accompanying drawings, which form a part of this document, and are shown in a manner that illustrates specific embodiments in which the present invention can be practiced. It should be understood that without departing from the scope of the present invention, other embodiments may be adopted, and structural changes may occur.

The present disclosure generally relates to doped ZnO electron transport layers for quantum dot light-emitting diodes and related products and methods. The electron transport layer can be placed between the cathode (from which electrons are injected into the quantum dot light-emitting diode) and the quantum dot light-emitting layer (in which electrons are recombined with the holes transferred from the hole transport layer to generate photons). Some of the electron transport layers described herein can advantageously have high electronic conductivity values. For example, some electron transport layers may include one or more dopants that increase the overall electron conductivity of the electron transport layer. An electron transport layer with a high electron conductivity value can advantageously facilitate the transport of electrons through the electron transport layer in large numbers.

The quantum dot light-emitting diode described in this article can be used in a wide variety of applications, such as flat-panel TV screens, digital cameras, mobile phones, AR/VR displays, Li-Fi communications, daylighting, and handheld game consoles.

Figure 1 shows a schematic diagram of a quantum dot light-emitting diode according to an embodiment. In FIG. 1, the quantum dot light-emitting diode includes a substrate 110, an anode 120 arranged on the substrate, a hole injection layer 130 arranged on the anode, a hole transfer layer 140 arranged on the hole injection layer, and a hole transfer layer 140 arranged on the hole injection layer. The quantum dot light-emitting layer 150 on the hole transport layer, the electron transport layer 160 placed on the quantum dot light-emitting layer, and the cathode 170 placed on the electron transport layer. As used herein, when a layer is referred to as being "disposed on another layer," it can be directly disposed on the layer or an intermediate layer may also be present. The layer "placed directly on another layer" means that there is no intermediate layer. Therefore, it should be understood that some quantum dot light emitting diodes may include other layers not shown in FIG. 1 and/or disposed between the two layers shown in FIG. 1. By way of example, in some embodiments, the quantum dot light emitting diode includes two hole injection layers and/or two hole transport layers. For example, in the case where the quantum dot light-emitting diode includes two hole injection layers, the second hole injection layer may be disposed between the first hole injection layer and the hole transfer layer. Similarly, the quantum dot light emitting diode including two hole transport layers may include a second hole transport layer disposed between the first hole transport layer and the quantum dot light emitting layer.

It should be understood that when the quantum dot light-emitting diode includes two or more layers of the same type (for example, two or more hole injection layers, two or more hole transport layers), Two layers of the same type can be the same or can be different in one or more ways. For example, a quantum dot light-emitting diode may include two or more layers of the same type, which are different in chemical composition, doping level, band gap, morphology, thickness, and/or in another way .

When a voltage is applied between the two electrodes, the anode 120 can inject holes into the hole injection layer 130. The hole can then be transferred via the hole transfer layer 140. The application of voltage can also cause the cathode 170 to inject and pass through the electron transport layer 160. The injected holes and injected electrons may be combined in the quantum dot light-emitting layer 150 (for example, at one or more of the quantum dots) to form excitons. The excitons can be recombined to emit light.

Some embodiments relate to methods of forming quantum dot light-emitting diodes, such as the quantum dot light-emitting diode shown in FIG. 1, the quantum dot light-emitting diode including one or more layers shown in FIG. 1, and/ Or include quantum dot light-emitting diodes with other layers not shown in FIG. 1. In some embodiments, the method includes assembling one or more layers together to form a quantum dot light emitting diode. The layers can be assembled by depositing one layer on the other to form a quantum dot light-emitting diode. The layers can be deposited in the order shown in Figure 1 (that is, the anode can be deposited on the substrate, the hole injection layer can be deposited on the anode, the hole transport layer can be deposited on the hole injection layer, The quantum dot light-emitting layer is deposited on the hole transport layer, the electron transport layer can be deposited on the quantum dot light-emitting layer and the cathode can be deposited on the electron transport layer), and the deposition is in the reverse order (that is, the electron transport layer can be deposited On the cathode, the quantum dot light-emitting layer can be deposited on the electron transport layer, the hole transport layer can be deposited on the quantum dot light-emitting layer, the hole injection layer can be deposited on the hole transport layer, and the anode can be deposited on the The hole injection layer and the substrate may be deposited on the anode) are deposited in the order shown in FIG. 1 or the reverse order but omitting the formation of one of the layers shown therein and/or in another suitable order. Various suitable forms of deposition can be used, such as spin coating, vacuum deposition, printing, spraying, coil coating, dip coating, stamping and the like.

Various suitable substrates can be used. In some embodiments, it can be beneficial for the substrate to have optical transparency, include one or more smooth surfaces, be easy to handle, and/or have excellent water resistance. In some embodiments, the substrate includes glass and/or polymer. Non-limiting examples of suitable polymeric substrates include polyethylene terephthalate substrates and polycarbonate substrates.

A variety of suitable anodes can be used. In some embodiments, the anode includes metal and/or ceramic. Non-limiting examples of suitable metals include nickel (Ni), platinum (Pt), gold (Au), silver (Ag), and iridium (Ir). Non-limiting examples of suitable ceramics include indium tin oxide (ITO) and indium zinc oxide (IZO).

In some embodiments, the hole injection layer includes polymer and/or ceramic. Non-limiting examples of suitable types of polymers include poly(3,4-ethylenedioxythiophene): polystyrene parasulfonate (PEDOT:PSS) derivatives, PVK, poly(methyl methacrylate) (PMMA) and/or polystyrene. Non-limiting examples of suitable ceramics include oxides, nitrides, carbides, sulfides, halide salts, citrates, nitrites, phosphates, thiocyanates, bicarbonates, and sulfide salts. Non-limiting examples of suitable oxides include MoO ₃ , Al ₂ O ₃ , WO ₃ , V ₂ O ₅ , NiO, MgO, HfO ₂ , Ga ₂ O ₃ , Gd ₂ O ₃ , La ₂ O ₃ , SiO ₂ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , TiO ₂ and BaO. An example of a suitable nitride is Si ₃ N ₄ . An example of a suitable carbide is SiC. An example of a suitable sulfide is ZnS. Non-limiting examples of suitable anions for halide salts include iodide anion, bromide anion, chloride anion and fluoride anion. Non-limiting examples of suitable cations for halide salts include copper cations (e.g., halide salts can be CuI, CuBr, CuI, and/or CuCl), alkali metal cations (e.g., halide salts can include lithium cations and/or can include LiF and/or LiCl) and alkaline earth metal cations (for example, the halide salt may contain magnesium cations and/or may contain MgF ₂ ). When the quantum dot light-emitting diode includes two or more hole injection layers, each hole injection layer may independently include one or more of the materials described above.

The hole transport layer may include polymers, organic molecules, and/or ceramics. Non-limiting examples of suitable polymers include poly((9,9-dioctylphenyl-2,7-diyl)-co-(4,4'-(N-(4-second butylphenyl) )) Diphenylamine)) (TFB), poly(9-vinylcarbazole) (PVK), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl) Benzidine) (polyTPD), poly(9-second butyl-2,7-difluoro-9H-azafluorene) (PVF), poly(9,9-dioctyl phenylene-2,7- Diyl) (PFO), poly((9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-茀)-alternative-2,7-(9,9 -Dioctyl pyridium)] (PFN-DOF), poly[(9,9-bis(3'-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7 -茀)-alternate-2,7-(9,9-dioctyl 茀)] (PFNBr), poly-N-vinylcarbazole, polyphenylene vinylene, poly(p-phenylene), polymethacrylate derivatives, Poly(9,9-octyl 茀), poly (spiro-茀), ginseng (3-methylphenylphenylamino) triphenylamine (m-MTDATA), poly(2-methoxy-5-(2 '-Ethylhexyloxy)-1,4-phenylacetylene] (MEH-PPV) and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4 -Phenylacetylene] (MDMO-PPV). Non-limiting examples of suitable organic molecules include TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine), NPB (N,N'-bis(1-naphthalene) Group)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine), 4,4',4"-ginseng (carbazol-9-yl) three Aniline (TCTA), 4'-bis(carbazol-9-yl)biphenyl (CBP), 3,3'-bis(9H-carbazol-9-yl)biphenyl (mCBP) and 1,3 -Bis(carbazol-9-yl)benzene (mCP). Non-limiting examples of suitable ceramics include copper iodide (I) (CuI), copper thiocyanate (I) (CuSCN), copper gallate (CuGaO ₂ ) And copper aluminate (CuAlO ₂ ). When the quantum dot light-emitting diode includes two or more hole transport layers, each hole transport layer can independently include one of the materials described above or More.

The hole transport layer can have various suitable forms. In some embodiments, the hole transport layer includes one or more types of nanoparticles. These nanoparticles can be crystalline, non-crystalline, or partially crystalline and partially non-crystalline. For example, in some embodiments, the hole transport layer includes nanocrystals. When the hole transport layer includes nanoparticles, it may further include one or more ligands that surround and/or inactivate the nanoparticles (for example, capped nanoparticles). Non-limiting examples of suitable ligands include oleic acid, 1-hexadecyl mercaptan, 1-octyl mercaptan, 1-dodecane mercaptan, 1-hexyl mercaptan, ethyl mercaptan, butane mercaptan, 1-pentyl mercaptan Alcohol, 1-Propanethiol, 1,2-ethanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octandithiol, 1,10-decanedithiol Mercaptan, silane (e.g. 3-aminopropyltriethoxysilane, triethoxysilyl butyraldehyde, 3-isocyanatopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 11- Cyanoundecyltrimethoxysilane, 3-propenoxypropyltrimethoxysilane and 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane), triethoxy Silyl undecyl aldehyde and N-(trimethoxysilyl propyl) ethylene diamine triacetic acid. When the quantum dot light-emitting diode includes two or more hole transport layers containing nanoparticles, each hole transport layer may independently include one or more of the ligands described above.

When the hole transport layer contains nano particles, the nano particles can have various suitable diameters. In some embodiments, the hole transport layer includes an average diameter less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, less than or equal to 75 nm, less than or equal to 50 nm, less than or equal to 25 nm, less than Nanoparticles of 10 nm or less, 5 nm or less or 2 nm or less. The hole transport layer may include an average diameter greater than or equal to 1 nm, greater than or equal to 2 nm, greater than or equal to 5 nm, greater than or equal to 10 nm, greater than or equal to 25 nm, greater than or equal to 50 nm, greater than or equal to 75 nm, Nanoparticles greater than or equal to 100 nm or greater than or equal to 150 nm. Combinations of the aforementioned ranges are also possible (for example, less than or equal to 200 nm and greater than or equal to 1 nm). Other ranges are also possible. The number and average diameter of nanoparticles can be determined by electron microscopy. When the quantum dot light-emitting diode includes two or more hole transport layers containing nanoparticles, each hole transport layer may independently include one or more of the average diameters in the above-described range Nanoparticles in the.

In some embodiments, it is desirable that the hole transport layer is relatively thin. Without wishing to be bound by any particular theory, it is believed that thicker layers can exhibit increased carrier absorption losses compared to thinner layers. The free carrier absorption loss may undesirably cause the light emitted by the quantum dot light-emitting layer to be reabsorbed in the hole transport layer instead of being emitted by the quantum dot light-emitting diode. The thickness of the hole transport layer can be less than or equal to 1 micron, less than or equal to 750 nm, less than or equal to 500 nm, less than or equal to 250 nm, less than or equal to 100 nm, less than or equal to 75 nm, less than or equal to 50 nm, Less than or equal to 25 nm, less than or equal to 10 nm, less than or equal to 5 nm, or less than or equal to 2 nm. In some embodiments, the thickness of the hole transport layer is greater than or equal to 1 nm, greater than or equal to 2 nm, greater than or equal to 5 nm, greater than or equal to 10 nm, greater than or equal to 25 nm, greater than or equal to 50 nm, greater than Or equal to 75 nm, greater than or equal to 100 nm, greater than or equal to 250 nm, greater than or equal to 500 nm, or greater than or equal to 750 nm. Combinations of the aforementioned ranges are also possible (for example, less than or equal to 1 micron and greater than or equal to 1 nm). Other ranges are also possible. The thickness of the hole transport layer can be measured by electron microscopy. When the quantum dot light emitting diode includes two or more hole transport layers, each hole transport layer can independently have a thickness of one or more of the above-described ranges.

The hole transport layer can be manufactured by a variety of suitable methods. In some embodiments, the hole transport layer is manufactured by a solution synthesis method containing nanocrystals. Nano crystals can be formed into the layer by, for example, spin coating, dipping, and/or spraying onto the substrate and/or other layers of the quantum dot light-emitting diode. When the quantum dot light emitting diode includes two or more hole transport layers, each hole transport layer can be independently manufactured by one or more of the methods described above.

The quantum dot light-emitting layer may include various suitable types of quantum dots. Quantum dots can be nanocrystalline, non-crystalline, or partially crystalline and partially non-crystalline. In some embodiments, the quantum dot light-emitting layer includes group II-VI compound semiconductor quantum dots, such as group II-VI compound semiconductor nanocrystal quantum dots. Non-limiting examples of quantum dots suitable for group II-VI compound semiconductor nanocrystals include quantum dots including CdS, CdSe, ZnS, ZnSe, HgS, HgSe, and/or HgTe. In some embodiments, the quantum dot light-emitting layer includes III-V compound semiconductor quantum dots, such as III-V compound semiconductor nanocrystal quantum dots. Non-limiting examples of nanocrystalline quantum dots suitable for III-V compound semiconductors include quantum dots including GaN, InN, AlN, GaP, GaAs, InP, GaSb, InSb, InAs, and alloys thereof. In some embodiments, the quantum dot light-emitting layer includes group IV-VI compound semiconductor quantum dots, such as group IV-VI compound semiconductor nanocrystal quantum dots. Non-limiting examples of quantum dots suitable for group IV-VI compound semiconductor nanocrystals include quantum dots including PbS, PbSe and/or PbTe. Some quantum dots may be Cd-free and/or substantially Cd-free (for example, some quantum dots may include Cd-free InP).

Quantum dots may have a uniform composition or may have a spatially varying composition. For example, in some embodiments, the quantum dot light-emitting layer includes core-shell quantum dots (eg, CdSe/ZnS core/shell, CdS/ZnSe core/shell, InP/ZnS core/shell, and the like). The core-shell quantum dot may include a core having a first composition and a shell layer surrounding the core having a second different composition. In some of these embodiments, the material forming the core has a relatively small band gap (such as CdSe, CdS, etc.) and the material forming the shell has a relatively large band gap (such as ZnS, ZnSe, etc.). By way of example, a core-shell quantum dot may have a core including CdSe and/or CdS and a shell including ZnS and/or ZnSe. Other examples suitable for core-shell quantum dots are described in US 9,887,318, which is incorporated herein by reference in its entirety for all purposes.

The quantum dots used in the quantum dot light-emitting layer described herein may have a diameter in the range of several nanometers to hundreds of nanometers. For example, the quantum dot light-emitting layer may include an average diameter of less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, less than or equal to 75 nm, less than or equal to 50 nm, less than or equal to 25 nm, less than or equal to Quantum dots equal to 10 nm, less than or equal to 5 nm, or less than or equal to 2 nm. The quantum dot light-emitting layer may include an average diameter greater than or equal to 1 nm, greater than or equal to 2 nm, greater than or equal to 5 nm, greater than or equal to 10 nm, greater than or equal to 25 nm, greater than or equal to 50 nm, greater than or equal to 75 nm, Quantum dots greater than or equal to 100 nm or greater than or equal to 150 nm. Combinations of the aforementioned ranges are also possible (for example, less than or equal to 200 nm and greater than or equal to 1 nm). Other ranges are also possible. The average diameter of the number of quantum dots in the quantum dot light-emitting layer can be measured by electron microscopy.

The quantum dots used in the quantum dot light-emitting layer described herein can emit light at a variety of suitable wavelengths. For example, the quantum dot light-emitting layer may include quantum dots emitting ultraviolet light, visible light, and/or infrared light. If the light is visible light, it can be a variety of suitable colors. By way of example, in some embodiments, the quantum dot light-emitting layer includes quantum dots that emit red light, orange light, yellow light, green light, blue light, indigo blue light, or violet light. In some embodiments, the quantum dot light-emitting layer is contained in a light emitting layer greater than or equal to 100 nm, greater than or equal to 150 nm, greater than or equal to 200 nm, greater than or equal to 250 nm, greater than or equal to 300 nm, greater than or equal to 350 nm, greater than or equal to Equal to 400 nm, greater than or equal to 450 nm, greater than or equal to 500 nm, greater than or equal to 550 nm, greater than or equal to 600 nm, greater than or equal to 650 nm, greater than or equal to 700 nm, greater than or equal to 750 nm, greater than or equal to 800 nm, greater than or equal to 850 nm, greater than or equal to 900 nm, greater than or equal to 950 nm, greater than or equal to 1 micron, greater than or equal to 1.5 microns, greater than or equal to 2 microns, greater than or equal to 2.5 microns, greater than or equal to 3 microns, Quantum dots that emit light at wavelengths greater than or equal to 3.5 microns, greater than or equal to 4 microns, or greater than or equal to 4.5 microns. In some embodiments, the quantum dot light-emitting layer is contained within 5 microns or less, 4.5 microns or less, 4 microns or less, 3.5 microns or less, 3 microns or less, 2.5 microns or less, or Equal to 2 microns, less than or equal to 1.5 microns, less than or equal to 1 micron, less than or equal to 950 nm, less than or equal to 900 nm, less than or equal to 850 nm, less than or equal to 800 nm, less than or equal to 750 nm, less than or equal to 700 nm, less than or equal to 650 nm, less than or equal to 600 nm, less than or equal to 550 nm, less than or equal to 500 nm, less than or equal to 450 nm, less than or equal to 400 nm, less than or equal to 350 nm, less than or equal to 300 nm, Quantum dots that emit light at wavelengths less than or equal to 250 nm, less than or equal to 200 nm, or less than or equal to 150 nm. Combinations of the ranges mentioned above are also possible (for example, greater than or equal to 100 nm and less than or equal to 5 microns). Other ranges are also possible. The wavelength emitted by the quantum dot light-emitting layer can be measured by using UV-vis-IR spectroscopy.

As described above, the quantum dot light-emitting diode described herein may include a doped ZnO electron transport layer. The electron transport layer may contain various suitable dopants. In some embodiments, the electron transport layer includes n-type dopants. Without wishing to be bound by any particular theory, it is believed that these dopants can advantageously reduce the Fermi energy and work function of the electron transport layer. It is believed that this reduction can help electron transfer through it and can cause the formation of ohmic contact between the electron transfer layer and the quantum dot light-emitting layer, which can increase the light-emitting diode by providing more electrons to the quantum dot light-emitting layer The charge recombination efficiency of the quantum of the body. Non-limiting examples of suitable dopants include group 1 dopants (e.g., Li, Na, K, Rb, and/or Cs), group 2 dopants (e.g., Be, Mg, Ca, Sr, and/or Ba ), Group 3 dopants (such as Sc, Y and/or La), Group 4 dopants (such as Ti, Zr and/or Hf), Group 5 dopants (such as V, Nb and/or Ta), Group 6 dopants (e.g. Cr, Mo and/or W), Group 7 dopants (e.g. Mn, Tc and/or Re), Group 8 dopants (e.g. Fe, Ru and/or Or Os), Group 9 dopants (e.g. Co, Rh and/or Ir), Group 13 dopants (e.g. B, Al, Ga, In and/or Tl), Group 14 dopants (e.g. C, Si, Ge, Sn and/or Pb) and/or Group 17 dopants (for example, F, Cl, Br and/or I). It should be understood that some electron transport layers may contain exactly one type of dopant, and some electron transport layers may contain more than one type of dopant. In these cases, each dopant may independently be one of the dopants listed above.

When the electron transport layer contains doped ZnO, the doped ZnO may contain various appropriate amounts of dopants. In some embodiments, the doped ZnO includes a certain amount of dopant such that the ratio of dopant to Zn is greater than or equal to 0.001, greater than or equal to 0.002, greater than or equal to 0.005, greater than or equal to 0.0075, greater than or equal to 0.01, Greater than or equal to 0.02, greater than or equal to 0.05, greater than or equal to 0.075, greater than or equal to 0.1, greater than or equal to 0.2, greater than or equal to 0.3, or greater than or equal to 0.4. In some embodiments, the doped ZnO includes a certain amount of dopant such that the ratio of dopant to Zn is less than or equal to 0.5, less than or equal to 0.4, less than or equal to 0.3, less than or equal to 0.2, less than or equal to 0.1, Less than or equal to 0.075, less than or equal to 0.05, less than or equal to 0.02, less than or equal to 0.01, less than or equal to 0.0075, less than or equal to 0.005, or less than or equal to 0.002. Combinations of the aforementioned ranges are also possible (for example, greater than or equal to 0.001 and less than or equal to about 0.5). When the electron transport layer includes ZnO including more than one dopant, the ratio of each dopant to Zn may independently be in one or more of the ranges described above. Similarly, the ratio of the total amount of all dopants in the electron transport layer to Zn can be within one or more of the ranges described above.

It should also be understood that some embodiments may relate to an electron transport layer containing undoped ZnO. These electron transport layers may further include doped ZnO or may lack doped ZnO. In some embodiments, the quantum dot light-emitting diode includes an electron transport layer including doped ZnO and further includes a second electron transport layer, and the second electron transport layer includes undoped ZnO. If the quantum dot light-emitting diode contains two electron transport layers containing doped ZnO, the two layers may contain the same type of doped ZnO and/or may contain different types of doped ZnO (for example, containing different dopants, doped Different combinations of impurities and/or different amounts of one or more dopants of ZnO). The electron transport layer can have various suitable forms. In some embodiments, the electron transport layer includes one or more nanoparticles (for example, one or more nanoparticles containing doped ZnO, one or more nanoparticles containing undoped ZnO). These nanoparticles can be crystalline, non-crystalline, or partially crystalline and partially non-crystalline. When the electron transport layer includes nanoparticles, it may further include one or more ligands that surround and/or inactivate the nanoparticles (for example, capped nanoparticles). Non-limiting examples of suitable ligands include oleic acid, 1-hexadecyl mercaptan, 1-octyl mercaptan, 1-dodecane mercaptan, 1-hexyl mercaptan, ethyl mercaptan, butane mercaptan, 1-pentyl mercaptan Alcohol, 1-Propanethiol, 1,2-ethanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 1,8-octandithiol, 1,10-decanedithiol Mercaptan, 3-mercaptopropionic acid, 4-mercaptobenzoic acid, benzoic acid, benzylamine, silane (e.g. 3-aminopropyltriethoxysilane, triethoxysilyl butyraldehyde, 3-isocyanate propyl Triethoxysilane, 3-mercaptopropyltrimethoxysilane, 11-cyanoundecyltrimethoxysilane, 3-propenyloxypropyltrimethoxysilane, triethoxysilane ten Monoaldehyde, N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid, 2-[methoxy(polyethyleneoxy)propyl]trimethoxysilane and tetraethylorthosilicate) and Adenosine 5'-monophosphate. When the quantum dot light-emitting diode includes two or more electron transport layers including nanoparticle, each electron transport layer may independently include one or more of the ligands described above.

When the electron transport layer contains nano particles, the nano particles can have various suitable diameters. In some embodiments, the electron transport layer includes an average diameter less than or equal to 200 nm, less than or equal to 150 nm, less than or equal to 100 nm, less than or equal to 75 nm, less than or equal to 50 nm, less than or equal to 25 nm, less than or equal to Nanoparticles equal to 10 nm, less than or equal to 5 nm, or less than or equal to 2 nm. The electron transport layer can include an average diameter greater than or equal to 1 nm, greater than or equal to 2 nm, greater than or equal to 5 nm, greater than or equal to 10 nm, greater than or equal to 25 nm, greater than or equal to 50 nm, greater than or equal to 75 nm, greater than Nanoparticles of 100 nm or greater or 150 nm. Combinations of the aforementioned ranges are also possible (for example, less than or equal to 200 nm and greater than or equal to 1 nm, or less than or equal to 5 nm and greater than or equal to 1 nm). Other ranges are also possible. The number and average diameter of nanoparticles can be determined by electron microscopy.

When the electron transport layer contains two or more types of nanoparticle, the diameter of each type of nanoparticle can independently be in one or more of the ranges listed above and/or the electron transport layer The diameter of all the nanoparticles together can be in one or more of the ranges listed above. Similarly, when the quantum dot light-emitting diode contains two or more electron transport layers containing nanoparticles, each electron transport layer can independently have the characteristics described in the preceding sentence.

A variety of suitable materials can be used in the cathode described herein. In some embodiments, it is advantageous for the cathode to have a relatively low work function, and can facilitate injection of electrons into the electron transport layer and/or into the electron injection layer. The work function of the cathode can be, for example, less than or equal to 4.8 eV, less than or equal to 4.6 eV, less than or equal to 4.4 eV, less than or equal to 4.2 eV, less than or equal to 3.9 eV, less than or equal to 3.7 eV, less than or equal to 3.5 eV, less than 3.2 eV or less, 3 eV or less, 2.8 eV or less, 2.6 eV or less, 2.4 eV or less, 2.2 eV or less, 2 eV or less or 1.8 eV or less. The work function of the cathode can be greater than or equal to 1.5 eV, greater than or equal to 1.8 eV, greater than or equal to 2 eV, greater than or equal to 2.2 eV, greater than or equal to 2.4 eV, greater than or equal to 2.6 eV, greater than or equal to 2.8 eV, greater than or equal to 3 eV, greater than or equal to 3.2 eV, greater than or equal to 3.5 eV, greater than or equal to 3.7 eV, greater than or equal to 3.9 eV, greater than or equal to 4.2 eV, greater than or equal to 4.4 eV or greater than or equal to 4.6 eV. Combinations of the aforementioned ranges are also possible (for example, less than or equal to 4.8 eV and greater than or equal to 1.5 eV, less than or equal to 3.9 eV and greater than or equal to 1.5 eV). Other ranges are also possible.

In some embodiments, the cathode includes metals and/or metal alloys with low work functions, such as Ca, Cs, Ba, Al, Mg, Ag, and/or alloys thereof. In some embodiments, the cathode includes an oxide having a low work function, such as ITO. Other examples of the types of materials that can be included in the cathode include alkali metal salts, halide salts, and alkali metal halide salts (such as LiF). The cathode may include a combination of two materials, at least one of which has a low work function, such as a combination of Ca and Al, a combination of LiF and Ca, and/or a combination of LiF and Al.

The quantum dot light-emitting diode described herein can be encapsulated in resin. For example, some of the quantum dot light-emitting diodes described herein can be encapsulated in a UV curable resin. In some embodiments, the resin includes unsaturated carboxylic acid (such as acrylic acid, methacrylic acid, benzoic acid, 3-butenoic acid, crotonic acid) and/or another suitable for promoting the positive aging of the encapsulated QD-LED Species. Non-limiting examples of suitable resins include those resins described in US Patent No. 9,780,256 (which is incorporated herein by reference in its entirety for all purposes).

In some embodiments, one or more of the layers described herein, such as an electron transport layer, a quantum dot light-emitting layer, a hole transport layer, or other layers, can be deposited by a solution coating process. Non-limiting examples of suitable solution coating processes include sol-gel coating, spin coating, printing, casting, stamping, dip coating, roll-to-roll coating and/or spray coating. In some embodiments, the solution coating process may be desirable because it may be less costly than other methods of forming thin films and/or may be performed at a lower temperature than other methods of forming thin films. The fluid used during the solution coating process can be a dispersion containing the precursor material and the dispersion solvent as described above. The dispersion solvent may include an aqueous solvent (such as water) and/or an organic solvent (such as alcohol). Non-limiting examples of suitable alcohols include isopropanol, ethanol, methanol, butanol, pentanol, cetyl alcohol, and/or 2-methoxyethanol.

After deposition, the film can be annealed in nitrogen, argon, helium, air, and/or oxygen at 70°C to 200°C.

Thermal annealing may include heating the deposited precursor to a temperature higher than or equal to 50°C, higher than or equal to 75°C, higher than or equal to 100°C, higher than or equal to 125°C, higher than or equal to 150°C, or higher than or equal to 175°C The temperature of ℃. Thermal decomposition may include heating the deposited precursor to less than or equal to 200°C, less than or equal to 175°C, less than or equal to 150°C, less than or equal to 125°C, less than or equal to 100°C or less than or equal to The temperature is 75°C. Combinations of the ranges mentioned above are also possible (for example, higher than or equal to 50°C and lower than or equal to 200°C). Other ranges are also possible.

Thermal annealing may include heating the deposited precursor to a temperature in one or more of the above-mentioned ranges for greater than or equal to 1 min, greater than or equal to 2 min, greater than or equal to 5 min, greater than or equal to 10 min, Time period greater than or equal to 20 minutes, greater than or equal to 30 minutes, greater than or equal to 1 hour, greater than or equal to 2 hours, greater than or equal to 5 hours, greater than or equal to 10 hours, greater than or equal to 20 hours, or greater than or equal to 50 hours . Thermal decomposition may include heating the deposited precursor to a temperature in one or more of the above-mentioned ranges for less than or equal to 100 hours, less than or equal to 50 hours, less than or equal to 20 hours, less than or equal to 10 hours, Time period less than or equal to 5 hours, less than or equal to 2 hours, less than or equal to 1 hour, less than or equal to 30 min, less than or equal to 20 min, less than or equal to 10 min, less than or equal to 5 min or less than or equal to 2 min . Combinations of the aforementioned ranges are also possible (for example, less than or equal to 1 min and greater than or equal to 1 hour). Other ranges are also possible.

The thermal annealing as described herein can be performed in the presence of nitrogen, argon, helium, air, and/or oxygen.

The following examples can better understand other aspects and advantages of some embodiments. Instance

The present invention will now be described in more detail with reference to the following examples. However, the examples described herein are for explanatory purposes only and are not intended to limit the scope of the teachings of the present invention in any way. Comparative example 1

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, TFB was spin-coated onto the PEDOT:PSS-coated substrate at 3000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. The quantum dots and undoped ZnO nanocrystals were sequentially deposited on the TFB by spin coating at 2000 rpm for 60 s and 30 s, respectively. The average diameter of undoped ZnO nanocrystals is less than 5 nm. Quantum dots are green Cd-based core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the undoped ZnO nanocrystal through a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide. Example 1

Prepare three different quantum dot light-emitting diodes, each containing an electron transport layer, which contains ZnO nanocrystals doped with different types of dopants. A quantum dot light-emitting diode contains an electron transport layer containing ZnO nanocrystals doped with 5 mol% Cs, and a quantum dot light-emitting diode contains an electron transport layer containing ZnO nanocrystals doped with 10 mol% Mg The electron transport layer and a quantum dot light emitting diode include an electron transport layer containing ZnO nanocrystals doped with 5 mol% Ga. Each quantum dot light-emitting diode is manufactured by following the procedure described in the following paragraphs.

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, TFB was spin-coated onto the PEDOT:PSS-coated substrate at 3000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. The quantum dots and doped ZnO nanocrystals were sequentially deposited on the TFB by spin coating at 2000 rpm for 60 s and 30 s, respectively. The average diameter of the doped ZnO nanocrystals is within 10% of the average diameter of the undoped ZnO nanocrystals of Comparative Example 1. Quantum dots are green Cd-based core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the alumina nanoparticle via a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide.

自標稱摻雜密度提取，其中E_i 為ZnO之固有費米能量；k 為波茲曼常數；T 為溫度；及N_{d / a} 為標稱供體/受體摻雜密度。方程式假設所有供體/受體均離子化，其對於此實例中所描述的電子傳遞層之摻雜水平之範圍而言為合理的。當電子傳遞層摻雜至足夠程度時，咸信所添加電子由摻雜物提供且相關聯之降低的費米能量引起摻雜ZnO電子傳遞層中之電子直接注入至量子點發光層之傳導帶。咸信此直接注入有利地截獲存在於量子點發光層中之界面缺損。Figure 2 shows the current density of Example 1 and Comparative Example 1 as a function of voltage. The solid lines with circles, triangles, and diamonds show the data from Example 1 and the solid lines with squares show the data from Comparative Example 1. Example 1 has a lower leakage current than Comparative Example 1 and is much more stable than Comparative Example 1, and the total resistance of Example 1 is similar to Comparative Example 1. This improvement can be attributed to the reduction of the injection barrier between the Al cathode and the ZnO electron transport layer due to the formation of ohmic contacts between the two materials. The ohmic contact between the Al cathode and the doped ZnO electron transport layer indicates that the conduction band of the doped ZnO electron transport layer has an energy close to the energy of the conduction band of the quantum dot light-emitting layer. It is believed that this causes the electrons in the doped ZnO electron transport layer to be effectively injected into the transport band of the quantum dot light-emitting layer. Without wishing to be bound by any specific theory, it is believed that the Fermi energy in ZnO can be based on

Extracted from the nominal doping density, where E _i is the intrinsic Fermi energy of ZnO; k is the Boltzmann constant; T is the temperature; and N _{d / a} is the nominal donor/acceptor doping density. The equation assumes that all donors/acceptors are ionized, which is reasonable for the range of doping levels of the electron transport layer described in this example. When the electron transport layer is doped to a sufficient degree, it is believed that the added electrons are provided by the dopant and the associated reduced Fermi energy causes the electrons in the doped ZnO electron transport layer to be directly injected into the conduction band of the quantum dot light-emitting layer . It is believed that this direct injection advantageously intercepts the interface defects existing in the quantum dot light-emitting layer.

FIG. 3 shows the current efficiency (CE) of Example 1 and Comparative Example 1 as a function of brightness and FIG. 4 shows the external quantum efficiency (EQE) of Example 1 and Comparative Example 1 as a function of brightness. The solid lines with circles, triangles, and diamonds show the data from Example 1 and the solid lines with squares show the data from Comparative Example 1. The CE of Example 1 is much higher than that of Comparative Example 1. In addition, the peak external quantum efficiency of Example 1 is higher than that of Comparative Example 1. Because Example 1 and Comparative Example 1 have a relatively low level of leakage current, it is believed that the high CE and high peak external quantum efficiency of Example 1 are derived from the reduced Fermi energy and the resulting reduced doped ZnO electron transport layer and quantum dots. The injection barrier between the layers is produced.

Figure 5 shows that the T ₅₀ service life of Example 1 and Comparative Example 1 varies with time. The solid lines with circles, triangles, and diamonds show the data from Example 1 and the solid lines with squares show the data from Comparative Example 1. The square, circle and triangle symbols show data from these samples with doped ZnO nanocrystals, which have Cs, Mg, and Ga. The lifetime of the device with the doped ZnO electron transport layer is higher than the lifetime of the device with the undoped ZnO electron transport layer. Comparative example 2

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, TFB was spin-coated onto the PEDOT:PSS-coated substrate at 3000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. The quantum dots and undoped ZnO nanocrystals were sequentially deposited on the TFB by spin coating at 2000 rpm for 60 s and 30 s, respectively. The average diameter of undoped ZnO nanocrystals is less than 5 nm. Quantum dots are green Cd-based core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the undoped ZnO nanocrystal through a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide. Example 2

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, TFB was spin-coated onto the PEDOT:PSS-coated substrate at 3000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. Quantum dots and ZnO nanocrystals doped with 5 mol% Rb were sequentially deposited on TFB by spin coating at 2000 rpm for 60 s and 30 s, respectively. The average diameter of the doped ZnO nanocrystals is within 10% of the average diameter of the undoped ZnO nanocrystals of Comparative Example 2. Quantum dots are green Cd-based core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the alumina nanoparticle via a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide.

Figure 6 shows the current density of Example 2 and Comparative Example 2 as a function of voltage. The solid line with a circle shows the data from Example 2 and the solid line with a square shows the data from Comparative Example 2. Example 2 has a higher leakage current than Comparative Example 2 and is more unstable than Comparative Example 2, and the total resistance of Example 2 is similar to Comparative Example 2. However, the turn-on voltage of Example 2 is 0.4 V, which is smaller than that of Comparative Example 2. This improvement can be attributed to the reduction of the injection barrier between the Al cathode and the ZnO electron transport layer due to the formation of ohmic contacts between the two materials. It is believed that the interface between the quantum dot light-emitting layer and the doped ZnO electron transport layer intercepts injected electrons.

FIG. 7 shows the current efficiency (CE) of Example 2 and Comparative Example 2 as a function of brightness and FIG. 8 shows the external quantum efficiency (EQE) of Example 2 and Comparative Example 2 as a function of brightness. The solid line with a circle shows the data from Example 2 and the solid line with a square shows the data from Comparative Example 2. The CE of Example 2 is much higher than that of Comparative Example 2. In addition, the peak external quantum efficiency of Example 2 is higher than that of Comparative Example 2. Although Example 2 and Comparative Example 2 have relatively high levels of leakage current, it is believed that the high CE and high peak external quantum efficiency of Example 2 are due to the reduced Fermi energy and the resulting reduced doped ZnO electron transport layer and quantum The injection barrier between the point emitting layers. Comparative example 3

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, TFB was spin-coated onto the PEDOT:PSS-coated substrate at 3000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. The quantum dots and undoped ZnO nanocrystals were sequentially deposited on the TFB by spin coating at 2000 rpm for 60 s and 30 s, respectively. The average diameter of undoped ZnO nanocrystals is less than 5 nm. Quantum dots are green Cd-based core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the undoped ZnO nanocrystal through a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide. Example 3

Two different quantum dot light-emitting diodes were prepared, each containing an electron transport double layer containing a layer of silane ligand-terminated ZnO nanocrystal and a layer of uncapped ZnO nanocrystal. A quantum dot light-emitting diode includes an electron transport layer that includes silane ligand-terminated ZnO nanocrystals doped with 5 mol% Mg (Example 3-1) and unterminated ZnO. Another quantum dot light-emitting diode includes an electron transport layer that includes silane ligand-terminated ZnO and unterminated ZnO nanocrystals doped with 5 mol% Mg (Example 3-2). Each quantum dot light-emitting diode is manufactured by following the procedure described in the following paragraphs.

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, TFB was spin-coated onto the PEDOT:PSS-coated substrate at 3000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. The quantum dots were deposited on the TFB by spin coating at 2000 rpm for 60 s. Subsequently, an electron transport double layer is formed. First, silane-terminated ZnO nanocrystals were spin-coated onto the quantum dots at 3500 rpm for 30 s. Subsequently, the resulting product was placed in a hot plate maintained at 70°C for 30 minutes. Subsequently, the uncapped ZnO nanocrystals were spin-coated onto the silane-capped ZnO nanocrystals. After these steps, the resulting product was placed in a hot plate kept at 100°C for 30 minutes. The average diameters of the two types of ZnO nanocrystals are within 10% of the average diameter of the undoped ZnO nanocrystals of Comparative Example 3. Quantum dots are green Cd-based core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the alumina nanoparticle via a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide.

Figure 9 shows the current density of Example 3-1, Example 3-2 and Comparative Example 3 as a function of voltage. The solid line shows the data from Comparative Example 3 and the dashed and dotted lines show the data from Examples 3-1 and 3-2, respectively. Examples 3-1 and 3-2 have a higher power-on voltage than Comparative Example 3 and a lower total resistance than Comparative Example 3. These improvements can be attributed to the reduction of the injection barrier between the cathode and the electron transport layer due to the formation of ohmic contacts between these layers. These improvements can also be due to the formation of ohmic contacts between the electron transport layer and the quantum dot light-emitting layer. It is believed that the ohmic contact between the electron transport layer and the quantum dot light-emitting layer is formed due to the low-level defects at the interface between the quantum dot light-emitting layer and the silane ligand-terminated ZnO electron transport layer. It is also believed that the defect lower layer at this interface reduces the work function of the ZnO electron transport layer blocked by the silane ligand by passivating the surface defect of ZnO with silicon, and the ZnO/silica (core/shell) nanoparticle shows a comparison Stronger quantum confinement effect on unblocked ZnO nanoparticles.

Figure 10 shows the external quantum efficiency (EQE) of Example 3-1, Example 3-2 and Comparative Example 3 as a function of current density. The solid line shows the data from Comparative Example 3 and the dashed and dotted lines show the data from Examples 3-1 and 3-2, respectively. The EQE of Example 3-2 is much higher than those of Comparative Example 3 and Example 3-1. In addition, the peak external quantum efficiency of Example 3-2 is higher than those of Comparative Example 3 and Example 3-1. It is believed that the slow efficiency drop and high peak external quantum efficiency of Example 3-2 are due to the improved charge balance in the quantum dot emitting layer. It is also believed that the reduced number of defects at the interface between the electron transport double layer and the quantum dot light-emitting layer and the associated reduced work function of the electron transport layer containing silane-terminated nanoparticles produce this improved charge balance , Silane-terminated nanoparticles contain Mg-doped ZnO. Example 4

And preparing a quantum dot light-emitting diode comprising an electron transport double layer, the electron transport double layer comprising a layer of silane ligand-terminated ZnO nanocrystals doped with 15 mol% Mg and a layer of uncapped ZnO nanocrystals. The procedure used is described in the following paragraphs.

The PEDOT:PSS solution was filtered through a syringe filter (0.45 μm) and then spin-coated onto the ITO-coated glass substrate at 3000 rpm for 60 s. Thereafter, the obtained substrate was baked at 145°C for 15 min. The PEDOT:PSS coated substrate was then transferred to a nitrogen-filled spherical box. Subsequently, the material for forming the hole transfer layer was spin-coated on the PEDOT:PSS-coated substrate at 2000 rpm for 30 s, and then the substrate was baked at 150°C for 30 min. The Cd-free InP quantum dots and doped ZnO nanocrystals were sequentially deposited on the hole transport layer by spin coating at 4000 rpm for 60 s. Subsequently, an electron transport double layer is formed. First, silane-terminated ZnO nanocrystals doped with 15 mol% Mg were spin-coated onto quantum dots at 3500 rpm for 30 s. Subsequently, the resulting product was placed in a hot plate maintained at 70°C for 30 minutes. Subsequently, the unblocked ZnO nanocrystals doped with 15 mol% Mg were spin-coated onto the silane blocked ZnO nanocrystals. After these steps, the resulting product was placed in a hot plate kept at 100°C for 30 minutes. The average diameters of the two types of ZnO nanocrystals are within 10% of the average diameter of the undoped ZnO nanocrystals of Comparative Example 3. Quantum dots are red Cd-free core/shell colloidal nanocrystals. The Al electrode (100 nm) was deposited on the alumina nanoparticle via a shadow mask using thermal evaporation. Finally, the device is encapsulated in a UV curable resin and then covered by a glass slide.

Figure 11 shows the current density of Example 4 as a function of voltage. The solid line (t1.1) and the dashed line (t2.3) show data from Example 4 measured 1 day and 2 days after manufacturing, respectively. Example 4 has a stable optical turn-on voltage of 1.7 V at t1.1 and t2.3. Figure 12 shows the external quantum efficiency (EQE) of Example 4 as a function of current density. The solid line (t1.1) and the dashed line (t2.3) show data from Example 4 measured 1 day and 2 days after manufacturing, respectively. The peak EQE of Example 4 was 13.17% at t1.1 at 276 Cd/m ² and 13.1% at t2.3 at 264 Cd/m ² . It is believed that the stable efficiency is due to the improved charge balance in the quantum dot light-emitting layer, due to the decrease in the amount of defects at the interface between the electron transport double layer and the quantum dot light-emitting layer, and the decrease in the work function of the electron transport double layer.

The embodiments herein are merely illustrative in nature, and therefore variations that do not depart from the gist of the described embodiments are intended to be within the scope of teaching. Such changes should not be regarded as a departure from the spirit and scope of the teaching.

Although several embodiments of the present invention have been described and illustrated herein, those skilled in the art will easily conceive a variety of other methods and/or structures to perform functions and/or obtain results and/or one or more of the The advantages described, and these changes and/or modifications are each considered to be within the scope of the present invention. More generally speaking, those familiar with this technology will easily understand that all the parameters, dimensions, materials and configurations described in this article are intended to be illustrative and the actual parameters, dimensions, materials and/or configurations will depend on the use of this Depending on the specific application of the invention teaching. Those skilled in the art will recognize or be able to determine many equivalents to the specific embodiments of the invention described herein using only routine experimentation. Therefore, it should be understood that the foregoing embodiments are presented only by examples and are within the scope of the appended patent application and its equivalents, and the present invention can be implemented in other ways different from the specific description and claims. The present invention relates to the individual features, systems, articles, materials, kits, and/or methods described herein. In addition, if these features, systems, products, materials, sets and/or methods are not inconsistent with each other, then any of two or more of these features, systems, products, materials, sets and/or methods Combinations are all included in the scope of the present invention.

All definitions as defined and used herein should be understood to be controlled within the dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

Unless indicated to the contrary, the indefinite article "一 (a/an)" used in this specification and the scope of the patent application should be understood to mean "at least one."

The phrase "and/or" as used herein in the specification and the scope of the patent application should be understood as meaning "either or both" of the elements so combined, that is, in some cases they exist in combination and in others In the case of uncombined elements. Multiple elements listed with "and/or" should be interpreted in the same way, that is, "one or more" elements so combined. There may be other elements other than the elements specifically identified by the "and/or" item, regardless of whether they are related or not related to the specifically identified elements. Therefore, as a non-limiting example, referring to "A and/or B" when used in conjunction with open-ended expressions such as "includes", in one embodiment, it can refer to only A (including elements other than B as appropriate) ; In another embodiment, it may refer to B only (including elements other than A as appropriate); in another embodiment, it may refer to both A and B (including other elements as appropriate); etc.

As used in this specification and the scope of the patent application, "or" should be understood to have the same meaning as "and/or" defined above. For example, when separating items in the list, "or" or "and/or" should be interpreted as inclusive, that is, including the number or list of elements and (as appropriate) at least one of the additional unlisted items And more than one. Terms that indicate only the opposite, such as "only one of" or "exactly one of" or when used in the scope of a patent application, "consisting of" will refer to the number or list of elements included It happens to be an element. Generally speaking, as used herein, the term "or" precedes an exclusive term (such as "any", "one of", "only one of" or "exactly one of") At the time, it should only be interpreted as indicating an exclusive alternative (ie, "one or the other, but not both"). When used in the scope of patent application, "mainly composed of" should have its ordinary meaning as used in the field of patent law.

As used in this specification and the scope of the patent application, the phrase "at least one" in relation to a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but It does not necessarily include each and at least one of each element specifically listed in the element list, and does not necessarily exclude any combination of elements in the element list. This definition also allows the existence of elements other than those specifically identified in the list of elements referred to by the phrase "at least one", regardless of whether they are related or not related to the specifically identified elements. Therefore, as a non-limiting example, "at least one of A and B" (or equivalently "at least one of A or B" or equivalently "at least one of A and/or B") In one embodiment, it may refer to at least one (including more than one as the case may be) A but not B (and optionally including elements other than B); in another embodiment, at least one (including more than one as the case may be A) B does not exist in A (and optionally includes elements other than A); in another embodiment, it means at least one (including more than one as the case may be) A and at least one (including more than one as the case may be) B (And other elements as appropriate); etc.

It should also be understood that, unless indicated to the contrary, in any method claimed herein that includes more than one step or operation, the order of the steps or operations of the method need not be limited to the order in which the steps or operations of the method are described.

In the scope of patent application and in the above description, such as "include", "include", "carry", "have", "contain", "involve", "hold", "consisting of" and similar All transitional phrases of the author should be understood as open, that is, it means including (but not limited to). Only the transitional phrases "consisting of" and "mainly composed of" should be closed or semi-closed transitional phrases respectively, as in Section 2111.03 of the United States Patent Office Manual of Patent Examining Procedures Elaborated.

110: substrate 120: anode 130: hole injection layer 140: hole transfer layer 150: Quantum dot light-emitting layer 160: electron transport layer 170: cathode

The accompanying drawings are included to provide a further understanding of the present invention and are incorporated into and constitute a part of this application, which illustrate the embodiments of the present invention and together with the implementations are used to explain the principle of the present invention. In the drawings: Figure 1 is a perspective view illustrating the structure of a quantum dot light-emitting diode according to some embodiments; Figure 2 is a diagram showing the current density of the quantum dot light-emitting diode described in Example 1 and Comparative Example 1 A graph showing changes in voltage; Fig. 3 is a graph showing the external quantum efficiency of the quantum dot light-emitting diodes described in Example 1 and Comparative Example 1 as a function of brightness; Fig. 4 is a graph showing the changes in Example 1 and Comparative Example 1 He described the quantum dot light emitting current efficiency diode of the function of the luminance variation of the drawings; FIG. 5 shows example 1 and Comparative example 1 described in the quantum dot light emitting diodes of the T ₅₀ period of use with the luminance change Figure 6 is a diagram showing the current density of the quantum dot light-emitting diode described in Example 2 and Comparative Example 2 as a function of voltage; Figure 7 is a diagram showing the quantum dot described in Example 2 and Comparative Example 2 The graph of the external quantum efficiency of light-emitting diodes as a function of brightness; FIG. 8 is a graph showing the current efficiency of the quantum dot light-emitting diodes described in Example 2 and Comparative Example 2 as a function of brightness; FIG. 9 is Shows the graph of the current density of the quantum dot light-emitting diodes described in Example 3 and Comparative Example 3 as a function of voltage; Figure 10 shows the exterior of the quantum dot light-emitting diodes described in Example 3 and Comparative Example 3 The graph of quantum efficiency as a function of current density; Figure 11 is a graph showing that the current density of the quantum dot light-emitting diode described in Example 4 varies with voltage; and Figure 12 is a graph showing the quantum described in Example 4 The graph of the external quantum efficiency of a point-emitting diode as a function of current density.

110: substrate

120: anode

130: hole injection layer

140: hole transfer layer

150: Quantum dot light-emitting layer

160: electron transport layer

170: cathode

Claims (33)

A quantum dot light-emitting diode, which comprises: First electrode A quantum dot light-emitting layer arranged on the first electrode; An electron transport layer disposed on the quantum dot light-emitting layer, wherein the electron transport layer includes nano particles, the nano particles include ZnO doped with one or more dopants, and the number of the nano particles is average The diameter is less than or equal to 5 nm; and A second electrode arranged on the electron transport layer. Such as the quantum dot light-emitting diode of claim 1, wherein at least one of the dopants is selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Al, Ga, In, Si, Ge and Sn. The quantum dot light-emitting diode of any one of the preceding claims, wherein the molar ratio of one or more dopants in the hole transport layer to Zn is greater than or equal to 0.001 and less than or equal to 0.5. Such as the quantum dot light-emitting diode of any of the foregoing claims, wherein the nano particles are crystalline. A quantum dot light-emitting diode according to any one of the preceding claims, wherein the quantum dot light-emitting diode further comprises a hole transport layer disposed between the first electrode and the quantum dot light-emitting layer. The quantum dot light emitting diode of claim 5, wherein the quantum dot light emitting diode further includes a hole injection layer disposed between the first electrode and the hole transfer layer. The quantum dot light-emitting diode of any one of the foregoing claims, wherein the electron transport layer includes a plurality of ligands surrounding the nanoparticles. Such as the quantum dot light-emitting diode of claim 7, wherein the plurality of ligands comprise silane. A quantum dot light-emitting diode according to any one of the preceding claims, which further includes a second electron transport layer. For example, the quantum dot light-emitting diode of claim 9, wherein the second electron transport layer includes nano particles, and the nano particles include ZnO. A method of manufacturing quantum dot light-emitting diodes, which comprises: Assemble the electron transport layer, the first electrode, the second electrode and the quantum dot light-emitting layer, Wherein the electron transport layer includes nano particles, and the nano particles include ZnO doped with one or more dopants, and The average diameter of the number of these nanoparticles is less than or equal to 5 nm. Such as the method of claim 11, wherein at least one of the dopants is selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Al, Ga, In, Si, Ge And Sn. The method according to any one of claims 11 to 12, wherein the molar ratio of the one or more dopants in the hole transport layer to Zn is greater than or equal to 0.001 and less than or equal to 0.5. The method of any one of claims 11 to 13, wherein the nanoparticles are crystalline. The method according to any one of claims 11 to 14, wherein the quantum dot light-emitting diode further comprises a hole transport layer disposed between the first electrode and the quantum dot light-emitting layer. The method of claim 15, wherein the quantum dot light-emitting diode further comprises a hole injection layer disposed between the first electrode and the hole transfer layer. The method according to any one of claims 11 to 16, wherein the electron transport layer comprises a plurality of ligands surrounding the nanoparticles. The method of claim 17, wherein the plurality of ligands comprise silane. The method according to any one of claims 11 to 18, wherein assembling the electron transport layer with the first electrode, the second electrode, and the quantum dot light-emitting layer includes performing a solution coating process. Such as the method of claim 19, wherein the solution coating process is selected from the group consisting of sol-gel coating, spin coating, printing, casting, stamping, dip coating, coil coating and spraying. The method according to any one of claims 19 to 20, wherein the electron transport layer is deposited by the solution coating process. The method according to any one of claims 19 to 21, wherein the quantum dot light-emitting layer is deposited by the solution coating process. The method according to any one of claims 19 to 23, wherein the hole transport layer is deposited by the solution coating process. The method of claim 23, wherein the quantum dot light-emitting layer is deposited on the hole transport layer. The method according to any one of claims 11 to 24, wherein the electron transport layer is deposited on the quantum dot light-emitting layer. The method of any one of claims 11 to 25, further comprising assembling a second electron transport layer and the electron transport layer, the first electrode, the second electrode, and the quantum dot light-emitting diode. The method of claim 26, wherein the second electron transport layer includes nano particles, and the nano particles include ZnO. The method according to any one of claims 26 to 27, wherein the second electron transport layer is deposited by a solution coating process. Such as the method of claim 28, wherein the solution coating process is selected from the group consisting of sol-gel coating, spin coating, printing, casting, stamping, dip coating, coil coating and spraying. The method according to any one of claims 11 to 29, which further comprises performing a thermal annealing step. The method of claim 30, wherein the thermal annealing is performed at a temperature higher than or equal to 70°C and lower than or equal to 200°C. The method of any one of claims 30 to 31, wherein the thermal annealing is performed in the presence of nitrogen, argon, helium, air, and/or oxygen. A quantum dot light-emitting diode formed by the method according to any one of claims 11 to 32.

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