Light emitting device and display apparatus
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TCL TECHNOLOGY GROUP CORPORATION
- Filing Date
- 2022-12-28
- Publication Date
- 2026-07-21
Smart Images
Figure CN118265342B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of display technology, and more particularly to a light-emitting device and a display apparatus. Background Technology
[0002] Currently, widely used light-emitting devices include organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs). The structure of a traditional light-emitting device generally includes an anode, a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and a cathode. Under the influence of an electric field, holes generated at the anode and electrons generated at the cathode move and are injected into the hole transport layer and electron transport layer, respectively, eventually migrating to the emissive layer. When these two electrons meet in the emissive layer, they generate excitons, which excite the light-emitting molecules to ultimately produce visible light.
[0003] The electron transport layer of existing light-emitting devices uses magnesium-doped inorganic particles, such as magnesium-doped zinc oxide. Although the incorporation of magnesium can effectively reduce the fluorescence quenching of the light-emitting layer material by inorganic particles, thereby improving the current efficiency of QLEDs, the incorporation of magnesium also reduces the electron mobility of inorganic particles, thus affecting the luminous efficiency of the light-emitting device. Summary of the Invention
[0004] In view of this, this application provides a light-emitting device and a display device, which aim to improve the problem of low luminous efficiency of existing light-emitting devices.
[0005] This application provides a light-emitting device, including a stacked anode, a light-emitting layer, an electron transport layer, and a cathode. The electron transport layer includes N stacked sub-electron transport layers, wherein N is greater than or equal to 2. The material of the sub-electron transport layers includes a composite material, and the composite material has a core-shell structure.
[0006] The core material comprises magnesium-doped inorganic particles, and the shell material comprises metal oxides; among the N stacked sub-electron transport layers, the magnesium doping amount in the core of the composite material in the sub-electron transport layer near the light-emitting layer is greater than the magnesium doping amount in the core of the composite material in the sub-electron transport layer near the cathode.
[0007] Optionally, in some embodiments of this application, the magnesium-doped inorganic particles include magnesium-doped zinc oxide.
[0008] Optionally, in some embodiments of this application, the metal oxide includes an undoped metal oxide, which includes at least one of MgO, SiO, and TiO2; and / or,
[0009] The metal oxide includes a doped metal oxide, which comprises metal oxide particles and a doping element. The metal oxide particles include at least one of ZnO, MgO, SiO, and TiO2, and the doping element includes at least one of Al, Li, and Sn.
[0010] Optionally, in some embodiments of this application, the average particle size of the composite material is 3–10 nm; and / or,
[0011] The thickness of the shell is 0.5–3 nm.
[0012] Optionally, in some embodiments of this application, in the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the core of the composite material of the N sub-electron transport layers gradually decreases along the direction from the light-emitting layer to the cathode. In two adjacent sub-electron transport layers, the difference in the molar content of magnesium in the magnesium-doped inorganic particles between the layers is 5 to 20%.
[0013] Optionally, in some embodiments of this application, in the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the light-emitting layer is 1-25%; and / or,
[0014] In the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the cathode is greater than 0 and less than or equal to 20%.
[0015] Optionally, in some embodiments of this application, in the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the light-emitting layer is 10-15%; and / or,
[0016] In the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the cathode is greater than 0 and less than or equal to 5%.
[0017] Optionally, in some embodiments of this application, the thickness of the electron transport layer is 10–50 nm; and / or,
[0018] Of the N stacked sub-electron transport layers, the thickness of the sub-electron transport layer closest to the light-emitting layer is 20% to 75% of the thickness of the electron transport layer; and / or,
[0019] In the N stacked sub-electron transport layers, the thickness of the sub-electron transport layer closest to the cathode is 10-50% of the thickness of the electron transport layer; and / or,
[0020] The thickness of each sub-electron transport layer is 10 to 90% of the thickness of the electron transport layer.
[0021] Optionally, in some embodiments of this application, the materials of the anode and the cathode independently include doped metal oxide particle electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The materials of the doped metal oxide particle electrodes include one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrodes include AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The materials of the elemental metal electrodes include at least one of Ag, Al, Cu, Au, Mo, Pt, Ca, and Ba; and / or,
[0022] The light-emitting device further includes a hole injection layer located between the anode and the light-emitting layer, wherein the hole injection layer is made of at least one of the following materials: 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethyl ether, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide; and / or,
[0023] The light-emitting device further includes a hole transport layer located between the anode and the light-emitting layer. The hole transport layer is made of materials including 1,2,4,5-tetra(trifluoromethyl)benzene, 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, and N,N'-bis(3-methylphenyl)-N,N'-biphenyl-4,4'-diamine. -Bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), polyaniline, polypyrrole, poly(p-)phenylene Vinyl, poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], copper phthalocyanine, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, poly(N-vinylcarbazole) and its derivatives, polymethyl... At least one of the following: acrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine, spironolactone (NPB), doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, and doped or undoped CuO; and / or,
[0024] The light-emitting layer is an organic light-emitting layer or a quantum dot light-emitting layer. The materials of the organic light-emitting layer include CBP:Ir(mppy)3(4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridine-C2,N)iridium(III)), TCTX:Ir(mmpy)(4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridine-C2,N)iridium), diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, and TBPe fluorescence. The material comprises at least one of TTPX fluorescent material, TBRb fluorescent material, and DBP fluorescent material; the material of the quantum dot emitting layer comprises at least one of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials; the material of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots each independently comprises at least one of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds; the group II-VI compounds include C dS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSe Te, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe The compounds include at least one of CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI compounds include at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe.The III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, and AlN P, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInN At least one of P, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI group compounds include at least one of CuInS2, CuInSe2, and AgInS2; the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion, including Cl... - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation, including CH3(CH2)n-2NH 3+ Or [NH3(CH2)nNH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+At least one of them, where X is a halide anion, including Cl... - ,Br - I - At least one of them.
[0025] Accordingly, this application also provides a display device, which includes the light-emitting device.
[0026] The electron transport layer in the light-emitting device described in this application comprises N stacked sub-electron transport layers. The material of each sub-electron transport layer is a composite material with a core-shell structure. The core material comprises magnesium-doped inorganic particles, and the shell material comprises metal oxides. Furthermore, in the N stacked sub-electron transport layers, the magnesium doping amount in the core of the composite material in the sub-electron transport layer closest to the light-emitting layer is greater than that in the core of the composite material in the sub-electron transport layer closest to the cathode. Along the direction from the light-emitting layer to the cathode, the magnesium doping amount in the core of the composite material in the N sub-electron transport layers shows a gradient decreasing trend, forming a conduction band energy gradient between the cathode and the sub-electron transport layer closest to the light-emitting layer. This reduces the quenching of quantum dots in the light-emitting layer, giving it excellent light-emitting performance, and also facilitates electron injection, thereby improving the luminous efficiency of the light-emitting device. Moreover, the core-shell structure of the sub-electron transport layer effectively improves the stability of the inorganic particles, thus extending the lifespan of the light-emitting device. Attached Figure Description
[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0028] Figure 1 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this application;
[0029] Figure 2 This is a schematic diagram of another light-emitting device provided in an embodiment of this application;
[0030] Figure 3 This is a flowchart illustrating a method for fabricating a light-emitting device according to an embodiment of this application;
[0031] Figure 4 This is a flowchart of another method for fabricating a light-emitting device provided in the embodiments of this application.
[0032] Figure label:
[0033] Light-emitting device 100; anode 10; light-emitting layer 20; electron transport layer 30; sub-electron transport layer 31; cathode 40; hole injection layer 50; hole transport layer 60; electron injection layer 70. Detailed Implementation
[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.
[0035] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.
[0036] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.
[0037] In this application, the term "on" forming another layer on a certain layer is a broad concept. It can mean that the formed other layer is adjacent to a certain layer, or it can mean that there are other spacer structures between the other layer and the certain layer. For example, when a top electrode is formed "on" the first carrier functional layer, the term "on" can mean that the formed top electrode is adjacent to the first carrier functional layer, or it can mean that there are other spacer structures between the top electrode and the first carrier functional layer, such as a light-emitting layer.
[0038] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms "first," "second," "third," etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order. The term "multiple" means "two or more".
[0039] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.
[0040] In recent years, researchers have begun to use magnesium-doped inorganic particles to replace pure inorganic particles as materials for the electron transport layer. Magnesium doping can weaken the quenching effect of inorganic particles on quantum dot materials in the light-emitting layer, thus maintaining the excellent luminescence performance of the light-emitting layer. However, magnesium affects the energy level structure and mobility of inorganic particles, which in turn affects the carrier injection balance, resulting in lower luminescence efficiency of the light-emitting device.
[0041] The technical solution of this application is as follows:
[0042] Firstly, please refer to Figure 1 This application provides a light-emitting device 100, which includes a stacked anode 10, a light-emitting layer 20, an electron transport layer 30 and a cathode 40. The electron transport layer 30 includes N stacked sub-electron transport layers 31, wherein N is greater than or equal to 2.
[0043] The sub-electron transport layer 31 is made of a composite material, which has a core-shell structure. The core material comprises magnesium-doped inorganic particles, and the shell material comprises a metal oxide.
[0044] In some embodiments, the magnesium-doped inorganic particles include magnesium-doped zinc oxide.
[0045] In some embodiments, the metal oxide includes an undoped metal oxide, which includes at least one of MgO, SiO, and TiO2; the metal oxide includes a doped metal oxide, which includes metal oxide particles and a doping element, wherein the metal oxide particles include at least one of ZnO, MgO, SiO, and TiO2, and the doping element includes at least one of Al, Li, and Sn.
[0046] In some embodiments, the average particle size of the composite material is 3–10 nm, for example, 4–8 nm, 5–10 nm, 6–9 nm, 3–7 nm, etc. This particle size range is beneficial for electron injection and transport in the electron transport layer 30; simultaneously, it facilitates the fabrication of a smooth-surfaced electron transport layer 30.
[0047] In some embodiments, the thickness of the shell ranges from 0.5 to 3 nm, for example, 0.8 to 2 nm, 1 to 1.5 nm, 0.9 to 2.5 nm, 1.2 to 2.4 nm, etc. Within this thickness range, the stability of the composite material can be increased; simultaneously, it facilitates electron transport in the electron transport layer 30.
[0048] In some embodiments, the amount of magnesium doping in the core of the composite material in the same sub-electron transport layer 31 is the same. Among the N stacked sub-electron transport layers 31, the amount of magnesium doping in the core of the composite material in the sub-electron transport layer 31 closer to the light-emitting layer 20 is greater than the amount of magnesium doping in the core of the composite material in the sub-electron transport layer 31 closer to the cathode 40.
[0049] It is understood that in this application, the amount of magnesium doping in the core of the composite material in the sub-electron transport layer refers to the average value of magnesium content in all cores of the entire sub-electron transport layer, that is: the amount of magnesium doping in the core of the composite material in the sub-electron transport layer = the total molar amount of Mg in all cores of the sub-electron transport layer / (the total molar amount of Mg in all cores of the sub-electron transport layer + the total molar amount of inorganic particles in all cores of the sub-electron transport layer).
[0050] In some embodiments, the amount of magnesium doping in the core of the composite material of the N sub-electron transport layers 31 decreases in a gradient direction along the direction from the light-emitting layer 20 to the cathode 40. This reduces the quenching of quantum dots in the light-emitting layer 20, resulting in excellent light-emitting performance, and also creates a conduction band energy level gradient, which is beneficial for electron injection, thereby improving the light-emitting efficiency of the light-emitting device 100.
[0051] In some embodiments, in the N stacked sub-electron transport layers 31, taking the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles as 100%, the molar content of magnesium in the core of the composite material of the N sub-electron transport layers 31 gradually decreases along the direction from the light-emitting layer 20 to the cathode 40. In adjacent sub-electron transport layers 31, the difference in the molar content of magnesium in the magnesium-doped inorganic particles between layers is 5–20%. In other words, the difference in the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer 31 near the light-emitting layer 20 is 5–20% compared to the difference between the magnesium-doped inorganic particles in the sub-electron transport layer near the cathode 40. For example, 6–12%, 8–15%, 10–20%, 14–18%, etc. Within this range of difference, it is beneficial to maintain the excellent light-emitting performance of the light-emitting layer 20 and to the injection and transport of electrons in the electron transport layer 30.
[0052] In some embodiments, among the N stacked sub-electron transport layers 31, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer 31 closest to the light-emitting layer 20 is 1-25%, for example, 10-15%, 15-20%, 5-25%, 8-18%, etc. Within this range, the excellent light-emitting performance of the light-emitting layer 20 can be maintained, while also facilitating the injection and transport of electrons in the sub-electron transport layer 31.
[0053] In some embodiments, among the N stacked sub-electron transport layers 31, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer 31 closest to the cathode 40 is greater than 0 and less than or equal to 20%, for example, 1–5%, 5–15%, 10–20%, 15–18%, etc. This range is beneficial for electron injection and transport in the sub-electron transport layer 31.
[0054] In some embodiments, among the N stacked sub-electron transport layers 31, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer 31 closest to the light-emitting layer 20 is 10-15%, for example, 10-12%, 11-14%, 12-14%, 13-15%, etc. Within this range, the excellent light-emitting performance of the light-emitting layer 20 can be maintained, while also facilitating the injection and transport of electrons in the sub-electron transport layer 31.
[0055] In some embodiments, among the N stacked sub-electron transport layers 31, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer 31 closest to the cathode 40 is greater than 0 and less than or equal to 5%, for example, 1-5%, 2-4%, 3-5%, 4-5%, etc. This range is beneficial for electron injection and transport in the sub-electron transport layer 31.
[0056] In some embodiments, the thickness of the electron transport layer 30 is 10–50 nm, for example, 20–40 nm, 15–45 nm, 25–35 nm, 20–30 nm, etc. This thickness range is beneficial for the injection and transport of electrons in the electron transport layer 30.
[0057] In some embodiments, among the N stacked sub-electron transport layers 31, the thickness of the sub-electron transport layer 31 closest to the light-emitting layer 20 is 20-75% of the thickness of the electron transport layer 30, for example, 20-70%, 30-50%, 40-55%, 35-60%, etc. This thickness range is beneficial for electron injection and transport within the sub-electron transport layer 31.
[0058] In some embodiments, among the N stacked sub-electron transport layers 31, the thickness of the sub-electron transport layer 31 closest to the cathode 40 is 10-50% of the thickness of the electron transport layer 30, for example, 20-40%, 30-50%, 15-35%, 25-45%, etc. This thickness range is beneficial for electron injection and transport within the sub-electron transport layer 31.
[0059] In some embodiments, the thickness of each of the N stacked sub-electron transport layers 31 is 10% to 90% of the thickness of the electron transport layer 30. This range is beneficial for the injection and transport of electrons within the electron transport layer 30.
[0060] In some embodiments, the electron transport layer 30 is composed of the composite material.
[0061] In other embodiments, the electron transport layer 30 may also include a polymethyl methacrylate (PMMA) layer, polymer 2,2′,7,7′-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9′-spirodifluorene (Spiro-OMeTAD), or other materials known to be added to the electron transport layer 50 to improve its performance.
[0062] The materials of the anode 10 and the cathode 40 independently include doped metal oxide particle electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The materials of the doped metal oxide particle electrodes include one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrodes include AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The materials of the elemental metal electrodes include at least one of Ag, Al, Cu, Au, Mo, Pt, Ca, and Ba. In this context, " / " indicates a stacked structure. For example, AZO / Ag / AZO represents a composite electrode formed by sequentially stacking AZO, Ag, and AZO layers.
[0063] The light-emitting layer 20 can be an organic light-emitting layer or a quantum dot light-emitting layer. When the light-emitting layer 20 is an organic light-emitting layer, the light-emitting device 100 can be an organic light-emitting device; when the light-emitting layer 20 is a quantum dot light-emitting layer, the light-emitting device 100 can be a quantum dot light-emitting device.
[0064] The organic light-emitting layer material includes at least one of the following: CBP:Ir(mppy)3(4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridine-C2,N)iridium(III)), TCTX:Ir(mmpy)(4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridine-C2,N)iridium), diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, and DBP fluorescent material.
[0065] The material of the quantum dot light-emitting layer includes one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials.
[0066] The materials of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots each independently include at least one of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds; the group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, and HgSeT. At least one of the following: e, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, and SnSe. At least one of Te, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, and Al At least one of PSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; wherein the group I-III-VI compounds include at least one of CuInS2, CuInSe2, and AgInS2.
[0067] As an example, the core-shell structured quantum dots include one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS.
[0068] The perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs. + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion, including Cl... - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation, including CH3(CH2)n-2NH 3+ Or [NH3(CH2)nNH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion, including Cl... - ,Br - I - At least one of them.
[0069] In some embodiments, please refer to Figure 2 The light-emitting device 100 further includes a hole injection layer 50 and a hole transport layer 60 located between the anode 10 and the light-emitting layer 20, that is, the light-emitting device 100 includes a stacked anode 10, a hole injection layer 50, a hole transport layer 60, a light-emitting layer 20, an electron transport layer 30, and a cathode 40.
[0070] The hole injection layer 50 is made of at least one of the following materials: 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethyl ether, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.
[0071] The hole transport layer 60 is made of materials including 1,2,4,5-tetratetrafluoromethylbenzene (TFB), 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro(spiro-TPD), N N'-Di(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine)(poly-TPD), polyaniline, polypyrrole, poly(p-)phenyleneethylene Poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], copper phthalocyanine, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, poly(N-vinylcarbazole) (PVK) and its derivatives At least one of the following: polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine, spiroNPB, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, and doped or undoped CuO.
[0072] In some embodiments, the light-emitting device 100 further includes an electron injection layer 70 located between the light-emitting layer 20 and the cathode 40. The material of the electron injection layer 70 includes inorganic and / or organic materials; the inorganic materials include one or more of the following: doped or undoped zinc oxide, barium oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, aluminum zinc oxide, manganese zinc oxide, tin zinc oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin sulfide, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate; the doped elements include one or more of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; the organic materials include at least one of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, and hydroxyquinoline compounds.
[0073] It is understood that the thickness of each layer in the light-emitting device 100 can be set as needed and is not limited here. In at least some embodiments, the thickness of the anode 10 is 10-100 nm, the thickness of the hole injection layer 50 is 10-50 nm, the thickness of the hole transport layer 60 is 10-50 nm, the thickness of the light-emitting layer 20 is 10-50 nm, the thickness of the electron transport layer 30 is 10-50 nm, and the thickness of the cathode 40 is 10-100 nm.
[0074] It is understood that the light-emitting device 100 may also be provided with some functional layers that are conventionally used in the light-emitting device 100 and help to improve the performance of the light-emitting device 100, such as electron blocking layer, hole blocking layer, interface modification layer, etc.
[0075] It is understood that the materials of each layer of the light-emitting device 100 can be adjusted according to the light-emitting requirements of the light-emitting device 100.
[0076] It is understood that the light-emitting device 100 can be an upright light-emitting device 100 or an inverted light-emitting device 100.
[0077] The light-emitting device 100 can be an organic light-emitting diode (OLED), a quantum dot light-emitting diode (QLED), a solar cell, a thin-film transistor, etc.
[0078] The electron transport layer 30 in the light-emitting device 100 described in this application includes N stacked sub-electron transport layers 31. The material of the sub-electron transport layer 31 includes a composite material, which has a core-shell structure. The core material includes magnesium-doped inorganic particles, and the shell material includes undoped or doped metal oxides. Furthermore, in the N stacked sub-electron transport layers 31, the magnesium doping amount in the core of the composite material in the sub-electron transport layer 31 closest to the light-emitting layer 20 is greater than that in the core of the composite material in the sub-electron transport layer 31 closest to the cathode 40. In the direction from the light-emitting layer 20 to the cathode 40, the magnesium doping amount in the core of the composite material of the N sub-electron transport layers 31 shows a gradient decreasing trend, forming a conduction band energy level gradient between the cathode 40 and the sub-electron transport layer 31 closest to the light-emitting layer 20. In this way, the quenching of quantum dots in the light-emitting layer can be reduced, giving the light-emitting layer excellent light-emitting performance, and it is also conducive to electron injection, thereby improving the light-emitting efficiency of the light-emitting device 100. On the other hand, the material of the sub-electron transport layer 31 is a core-shell structure composite material, which can effectively improve the stability of inorganic particles, thereby extending the life of the light-emitting device 100.
[0079] Secondly, please refer to Figure 3 This application also provides a method for fabricating a light-emitting device 100, comprising the following steps:
[0080] S11. Provide an anode 10 and form a light-emitting layer 20 on the anode 10;
[0081] S12. Provide the composite material described above, and form the electron transport layer 30 described above on the light-emitting layer 20;
[0082] S13. A cathode is formed on the electron transport layer 30 to obtain a light-emitting device 100.
[0083] When the light-emitting device 100 further includes a hole functional layer, step S11 is: providing an anode 10, and sequentially forming a stacked hole functional layer and a light-emitting layer 20 on the anode 10, wherein the hole functional layer includes at least one of a hole injection layer 50 and a hole transport layer 60.
[0084] When the light-emitting device 100 further includes an electron injection layer 70, step S13 is: to sequentially form an electron injection layer 70 and a cathode 40 on the electron transport layer 30 to obtain the light-emitting device 100.
[0085] Please see Figure 4 This application also provides another method for fabricating a light-emitting device 100, comprising the following steps:
[0086] S21, Provide cathode 40;
[0087] S22. Provide the composite material described above, and form the electron transport layer 30 described above on the cathode 40;
[0088] S23. A light-emitting layer 20 and an anode 10 are sequentially formed on the electron transport layer 30 to obtain a light-emitting device 100.
[0089] When the light-emitting device 100 further includes an electron injection layer 70, step S21 is: providing a cathode 40 and forming the electron injection layer 70 on the cathode 40. Step S22 is: providing the composite material described above and forming the electron transport layer 30 described above on the electron injection layer 70.
[0090] When the light-emitting device 100 further includes a hole functional layer, step S23 is: forming a light-emitting layer 20, a hole functional layer and an anode 10 sequentially on the electron transport layer 30 to obtain the light-emitting device 100, wherein the hole functional layer includes at least one of a hole injection layer 50 and a hole transport layer 60.
[0091] In the above two methods for preparing light-emitting devices:
[0092] The materials of the anode 10, the light-emitting layer 20, the electron transport layer 30, the cathode 40, the hole injection layer 50, the hole transport layer 60, and the electron injection layer 70 are as described above and will not be repeated here.
[0093] The method for fabricating the light-emitting device 100 further includes a step of heat treatment on the fabricated light-emitting device 100. The heat treatment can accelerate the forward aging of the light-emitting device 100 and improve its efficiency and lifespan.
[0094] In the fabrication method of the light-emitting device 100, the anode 10, hole injection layer 50, hole transport layer 60, light-emitting layer 20, electron transport layer 30, electron injection layer 70, and cathode 40 can be fabricated using conventional techniques in the art, such as chemical or physical methods. Chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods include physical deposition and solution methods. Physical deposition methods include thermal evaporation deposition, electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition, atomic layer deposition, and pulsed laser deposition, etc.
[0095] In some embodiments, the provided anode 10 is an anode with a substrate, and the provided cathode 40 is a cathode with a substrate. The substrate may be a rigid substrate or a flexible substrate. In some embodiments, the substrate material includes at least one selected from glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.
[0096] In some embodiments, the above preparation method further includes a pretreatment step of the anode 10 or cathode 40. In at least one embodiment, the pretreatment includes: cleaning the anode 10 or cathode 40 with a cleaning agent to initially remove surface stains, then ultrasonically cleaning it sequentially in deionized water, isopropanol, acetone, and deionized water for 20 minutes each to remove surface impurities, and finally drying it with high-purity nitrogen.
[0097] In some embodiments, the above preparation method further includes a step of encapsulating the light-emitting device 100 after it has been prepared. The encapsulation process can be performed using conventional machine encapsulation or manually. Preferably, the oxygen and water content in the encapsulation environment is both below 0.1 ppm to ensure the stability of the light-emitting device 100.
[0098] Thirdly, this application also relates to a display device, which includes the light-emitting device 100.
[0099] The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.
[0100] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.
[0101] In the following embodiments, it should be noted that in Zn x Mg y In O, x and y represent the values in Zn. x Mg y The mole fractions of Zn and Mg in O, for example, Zn 0.9 Mg 0.1 The number of moles of Zn in O and Zn 0.9 Mg 0.1 The ratio of the sum of the molar numbers of Zn and Mg in O is 0.9. Furthermore, the chemical formula Zn...0.9 Mg 0.1 The "O" only indicates that the substance is composed of Zn, Mg, and O elements. The aforementioned chemical formula does not specify the mole fraction of O. It can be understood that Zn... 0.9 Mg 0.1 The sum of the mole fractions of Zn and Mg in O is 1.
[0102] Example 1
[0103] A glass substrate with an ITO anode 10 is provided, wherein the thickness of the ITO anode 10 is 30nm. The glass substrate with the ITO anode 10 is cleaned with a cleaning agent to initially remove the stains on the surface. Then, it is ultrasonically cleaned in deionized water, isopropanol, acetone and deionized water for 20 minutes each to remove the impurities on the surface. Finally, it is dried with high-purity nitrogen.
[0104] PEDOT:PSS was spin-coated onto ITO anode 10 and annealed at 200℃ for 20 min to obtain a hole injection layer 50 with a thickness of 20 nm.
[0105] TFB was spin-coated onto the hole injection layer and annealed at 150°C for 20 min to obtain a hole transport layer 60 with a thickness of 30 nm.
[0106] CdSe / ZnS blue quantum dot material was spin-coated onto the hole transport layer 60 and annealed at 100°C for 5 min to obtain a light-emitting layer 20 with a thickness of 30 nm.
[0107] A composite material is spin-coated onto the light-emitting layer 20, wherein the core material of the composite material is Zn. 0.9 Mg 0.1 O, the shell of the composite material is made of MgO, annealed at 80°C for 5 min, to obtain the first sub-electron transport layer 31 with a thickness of 15 nm;
[0108] A composite material is spin-coated onto the first sub-electron transport layer 31, wherein the core material of the composite material is Zn. 0.95 Mg 0.05 O, the shell of the composite material is made of MgO, annealed at 80°C for 5 min, to obtain a second sub-electron transport layer 31 with a thickness of 10 nm;
[0109] A composite material is spin-coated onto the second sub-electron transport layer 31, wherein the core material of the composite material is ZnO and the shell material of the composite material is MgO. The mixture is then annealed at 80°C for 5 min to obtain a third sub-electron transport layer 31 with a thickness of 5 nm.
[0110] Al is deposited on the third sub-electron transport layer 31 to obtain a cathode 40 with a thickness of 50 nm;
[0111] Encapsulation was performed in an environment where both oxygen and water content were below 0.1 ppm to obtain the light-emitting device 100.
[0112] In this embodiment, the electron transport layer 30 includes three sub-electron transport layers 31.
[0113] Example 2
[0114] This embodiment is basically the same as Embodiment 1, except that the electron transport layer 30 in this embodiment includes three sub-electron transport layers 31. Along the direction from the light-emitting layer 20 to the cathode 40, the composite material of the three sub-electron transport layers 31 in this embodiment is Zn. 0.85 Mg 0.15 O, the shell material is MgO; the core material is Zn. 0.9 Mg 0.1 O, the shell material is MgO; the core material is Zn. 0.95 Mg 0.05 O, the shell material is MgO; the thicknesses are 10nm, 5nm, and 5nm respectively.
[0115] Example 3
[0116] This embodiment is basically the same as Embodiment 1, except that the electron transport layer 30 in this embodiment includes two sub-electron transport layers 31. Along the direction from the light-emitting layer 20 to the cathode 40, the composite material of the two sub-electron transport layers 31 in this embodiment is Zn as the core material. 0.85 Mg 0.15 The shell material is MgO; the core material is ZnO; and the shell material is MgO; the thicknesses are 20 nm and 10 nm, respectively.
[0117] Comparative Example 1
[0118] This comparative example is basically the same as Example 1, except that the electron transport layer 30 in this comparative example is made of ZnO for the core and MgO for the shell, with a thickness of 30 nm.
[0119] Comparative Example 2
[0120] This comparative example is basically the same as Example 1, except that the electron transport layer 30 in this comparative example is made of Zn as the core material. 0.85 Mg 0.15 O, the shell material is MgO, and the thickness is 20nm.
[0121] Comparative Example 3
[0122] This comparative example is basically the same as Example 1, except that the electron transport layer 30 in this comparative example includes two sub-electron transport layers 31. Along the direction from the light-emitting layer 20 to the cathode 40, the materials of the two sub-electron transport layers 31 in this comparative example are Zn and Zn, respectively. 0.85 Mg 0.15 O and ZnO; thicknesses of 20 nm and 10 nm, respectively.
[0123] The luminous efficiency CE@max and lifetime T95@1knit of the light-emitting devices 100 in Examples 1-3 and Comparative Examples 1-3 were tested, and the test results are detailed in Table 1 below.
[0124] The luminous efficacy CE@max was tested using a PR650 luminance meter and a Keithley meter to measure luminance and current, respectively. The current density was obtained based on the luminous area, and the luminous efficacy CE@max was calculated by the ratio of luminance to current density.
[0125] The lifetime test T95@1knit refers to the time it takes for the device's brightness to decay to a certain percentage of its maximum brightness under a constant current drive of 2mA. The time it takes for the brightness to decay to 95% of its maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the lifetime testing cycle, device lifetime testing is usually performed at high brightness by accelerating device aging, and the lifetime at low brightness is obtained by fitting the decay data using a decay fitting formula. For example, the lifetime at 1knit is denoted as T95@1knit, and the calculation formula is as follows:
[0126]
[0127] Among them, T95 L For lifespan at low brightness, it is generally taken as the lifespan at 1 knit, T95. H The lifetime at high brightness, i.e., the measured lifetime, L H L is the maximum brightness that the device accelerates to. L The value is typically 1 knit, and A is the acceleration factor, which is set to 1.7.
[0128] Table 1:
[0129] CE@max(cd / A) T95@1knit(hrs) Example 1 14.8 108 Example 2 15.5 115 Example 3 11.2 85 Comparative Example 1 7.8 24 Comparative Example 2 9.6 30 Comparative Example 3 12.6 42
[0130] As shown in Table 1:
[0131] Compared to Comparative Example 1, the light-emitting device 100 of Comparative Example 3 has higher luminous efficiency and longer lifespan. This may be because the electron transport layer 30 of the light-emitting device 100 of Comparative Example 3 is made of magnesium-doped zinc oxide. The magnesium doping reduces the influence of the electron transport layer 30 on the light emission of the light-emitting layer 20.
[0132] Compared to Comparative Example 3, the light-emitting device 100 of Example 3 has a longer lifespan. This may be because the material of the sub-electron transport layer 31 in Example 3 is a core-shell composite material. This structure improves the stability of inorganic particles, thereby extending the lifespan of the light-emitting device 100.
[0133] Compared to Comparative Examples 1-2, the light-emitting devices 100 of Examples 1-3 exhibit higher luminous efficiency; compared to Comparative Examples 1-3, the light-emitting devices 100 of Examples 1-3 also exhibit longer lifetimes. This may be because the electron transport layer 30 of Examples 1-3 comprises N stacked sub-electron transport layers 31. The material of the sub-electron transport layer 31 includes a composite material with a core-shell structure. The core material comprises magnesium-doped inorganic particles, and the shell material comprises a metal oxide. On the one hand, the presence of magnesium in the core of the composite material in the sub-electron transport layer 31 near the light-emitting layer 20 can reduce the influence of inorganic particles in the core of the composite material in the sub-electron transport layer 31 on the light emission of the light-emitting layer 20. On the other hand, among the N stacked sub-electron transport layers 31, the core of the composite material in the sub-electron transport layer 31 closer to the light-emitting layer 20 has a higher amount of magnesium doping, while the core of the composite material in the sub-electron transport layer 31 closer to the cathode 40 has a lower amount of magnesium doping. In the direction from the light-emitting layer 20 to the cathode 40, the amount of magnesium doping in the core of the composite material of the N sub-electron transport layers 31 shows a gradient decreasing trend, forming a conduction band energy level gradient between the cathode 40 and the sub-electron transport layer 31 closest to the light-emitting layer 20, which is beneficial for electron injection and thus improves the light emission efficiency of the light-emitting device 100. In addition, the material of the sub-electron transport layer 31 is a core-shell structure composite material, which improves the stability of inorganic particles and thus extends the lifespan of the light-emitting device 100.
[0134] The light-emitting device and display apparatus provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A light-emitting device, comprising a stacked anode, a light-emitting layer, an electron transport layer, and a cathode, characterized in that, The electron transport layer comprises N stacked sub-electron transport layers, wherein N is greater than or equal to 2, and the material of the sub-electron transport layer includes a composite material, wherein the composite material has a core-shell structure. The core material comprises magnesium-doped inorganic particles, and the shell material comprises metal oxides; among the N stacked sub-electron transport layers, the magnesium doping amount in the core of the composite material in the sub-electron transport layer near the light-emitting layer is greater than the magnesium doping amount in the core of the composite material in the sub-electron transport layer near the cathode.
2. The light-emitting device according to claim 1, characterized in that, The magnesium-doped inorganic particles include magnesium-doped zinc oxide.
3. The light-emitting device according to claim 1, characterized in that, The metal oxide includes an undoped metal oxide, which includes at least one of MgO, SiO, and TiO2; and / or, The metal oxide includes a doped metal oxide, which comprises metal oxide particles and a doping element. The metal oxide particles include at least one of ZnO, MgO, SiO, and TiO2, and the doping element includes at least one of Al, Li, and Sn.
4. The light-emitting device according to claim 1, characterized in that, The average particle size of the composite material is 3–10 nm; and / or, The thickness of the shell is 0.5–3 nm.
5. The light-emitting device according to claim 1, characterized in that, In the N stacked sub-electron transport layers, taking the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles as 100%, the molar content of magnesium in the core of the composite material of the N sub-electron transport layers gradually decreases in the direction from the light-emitting layer to the cathode. In two adjacent sub-electron transport layers, the difference in the molar content of magnesium in the magnesium-doped inorganic particles in the layers is 5 to 20%.
6. The light-emitting device according to claim 1, characterized in that, In the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the light-emitting layer is 1-25%; and / or, In the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the cathode is greater than 0 and less than or equal to 20%.
7. The light-emitting device according to claim 1, characterized in that, In the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the light-emitting layer is 10-15%; and / or, In the N stacked sub-electron transport layers, with the sum of the molar content of magnesium in the magnesium-doped inorganic particles and the molar content of the inorganic particles being 100%, the molar content of magnesium in the magnesium-doped inorganic particles in the sub-electron transport layer closest to the cathode is greater than 0 and less than or equal to 5%.
8. The light-emitting device according to claim 1, characterized in that, The thickness of the electron transport layer is 10–50 nm; and / or, Of the N stacked sub-electron transport layers, the thickness of the sub-electron transport layer closest to the light-emitting layer is 20% to 75% of the thickness of the electron transport layer; and / or, In the N stacked sub-electron transport layers, the thickness of the sub-electron transport layer closest to the cathode is 10-50% of the thickness of the electron transport layer; and / or, The thickness of each sub-electron transport layer is 10 to 90% of the thickness of the electron transport layer.
9. The light-emitting device according to claim 1, characterized in that, The materials of the anode and the cathode independently include doped metal oxide particle electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The materials of the doped metal oxide particle electrodes include one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrodes include AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The materials of the elemental metal electrodes include at least one of Ag, Al, Cu, Au, Mo, Pt, Ca, and Ba; and / or... The light-emitting device further includes a hole injection layer located between the anode and the light-emitting layer, wherein the hole injection layer is made of at least one of the following materials: 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethyl ether, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide; and / or, The light-emitting device further includes a hole transport layer located between the anode and the light-emitting layer. The hole transport layer is made of materials including 1,2,4,5-tetra(trifluoromethyl)benzene, 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, and N,N'-bis(3-methylphenyl)-N,N'-biphenyl-4,4'-diamine. -Bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), polyaniline, polypyrrole, poly(p-)phenylene Vinyl, poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], copper phthalocyanine, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, poly(N-vinylcarbazole) and its derivatives, polymethyl... At least one of the following: acrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine, spironolactone (NPB), doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, and doped or undoped CuO; and / or, The light-emitting layer is an organic light-emitting layer or a quantum dot light-emitting layer. The materials of the organic light-emitting layer include CBP:Ir(mppy)3(4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridine-C2,N)iridium(III)), TCTX:Ir(mmpy)(4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridine-C2,N)iridium), diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, and TBPe fluorescence. The material comprises at least one of TTPX fluorescent material, TBRb fluorescent material, and DBP fluorescent material; the material of the quantum dot emitting layer comprises at least one of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials; the material of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots each independently comprises at least one of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds; the group II-VI compounds include C dS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSe Te, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe The compounds include at least one of CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI compounds include at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe.The III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, and AlN P, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInN At least one of P, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI group compounds include at least one of CuInS2, CuInSe2, and AgInS2; the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion, including Cl. - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation, including CH3(CH2)n-2NH 3+ Or [NH3(CH2)nNH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion, including Cl. - ,Br - I - At least one of them.
10. A display device, characterized in that, The display device includes a light-emitting device as described in any one of claims 1 to 9.