Compounds, light-emitting devices and their preparation methods and display devices

Abstract

This application discloses a compound, a light-emitting device, a preparation method thereof, and a display device. The compound is obtained by coumarin and / or coumarin derivatives being coordinated and linked with nano-metal oxides. The preparation method of the light-emitting device includes the step of preparing an electron transport layer. In the process of preparing the electron transport layer, an electron transport material layer is first prepared, the material of which includes the compound. Then, the electron transport material layer is treated with a first illumination condition to obtain an electron transport precursor layer. Next, an upper functional film is prepared on one side of the electron transport precursor layer. After the upper functional film is prepared, the electron transport precursor layer is treated with a second illumination condition to obtain the electron transport layer. This method has the advantages of convenient operation and suitability for industrial production.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, specifically to a compound, a light-emitting device, a method for preparing the same, and a display device. Background Technology

[0002] Light-emitting devices include, but are not limited to, Organic Light-Emitting Diodes (OLEDs) and Quantum Dot Light-Emitting Diodes (QLEDs). These devices typically have a "sandwich" structure, consisting of an anode, a cathode, and an emissive layer. The anode and cathode are positioned opposite each other, with the emissive layer located between them. The light-emitting principle of these devices is as follows: electrons are injected from the cathode into the emissive layer, and holes are injected from the anode into the emissive layer. Electrons and holes recombine in the emissive layer to form excitons, which then release photons through radiative transitions, thus emitting light.

[0003] In the fabrication process of light-emitting devices, the functional materials or fabrication processes used to prepare the upper thin film can adversely affect the performance of the lower thin film, thereby reducing the photoelectric performance and lifespan of the light-emitting device. For example, when other functional thin films (such as light-emitting layers or cathodes) are prepared on top of the electron transport layer, damage can be caused to the electron transport layer, resulting in a decrease in the electron conduction capability of the electron transport layer, which is detrimental to improving the overall performance of the light-emitting device.

[0004] Therefore, improving the materials of the electron transport layer to reduce the adverse effects on the electron transport layer when other functional thin films are fabricated on top of it is of great significance to the application and development of light-emitting devices. Summary of the Invention

[0005] This application provides a compound, a light-emitting device, a method for preparing the same, and a display device thereof. The compound can be used as an electron transport material for the light-emitting device.

[0006] The technical solution of this application is as follows:

[0007] In a first aspect, this application provides a compound having the structure shown in the general formula (I):

[0008]

[0009] In general formula (I), R is selected from hydrogen atom, amino, carboxyl or hydrocarbon group, X is selected from nano metal oxide, and the metal atom of the nano metal oxide is coordinated with the double bond oxygen.

[0010] Secondly, this application also provides a method for preparing a compound, comprising the following steps:

[0011] A mixture of the first compound and the second compound is provided;

[0012] The mixture was heat-treated in an inert gas atmosphere to obtain the compound;

[0013] The first compound has the structure shown in general formula (II):

[0014]

[0015] In general formula (II), R is selected from hydrogen atom, amino group, carboxyl group or hydrocarbon group;

[0016] The second compound is selected from nano-metal oxides.

[0017] Thirdly, this application provides a light-emitting device, including:

[0018] anode;

[0019] The cathode is disposed opposite to the anode;

[0020] A light-emitting layer is disposed between the anode and the cathode; and

[0021] An electron transport layer is disposed between the light-emitting layer and the cathode;

[0022] The material of the electron transport layer includes any of the compounds described in the first aspect, or compounds prepared by any of the preparation methods described in the second aspect.

[0023] Fourthly, this application also provides a method for fabricating a light-emitting device, wherein the light-emitting device has an upright structure, and the fabrication method includes the following steps:

[0024] An anode is provided, and a light-emitting layer is formed on one side of the anode;

[0025] An electron transport material layer is formed on the side of the light-emitting layer away from the anode. The material of the electron transport material layer includes any of the compounds described in the first aspect, or compounds prepared by any of the preparation methods described in the second aspect.

[0026] The electron transport material layer is treated with the first illumination condition to obtain the electron transport precursor layer;

[0027] A cathode is formed on the side of the electron transport precursor layer away from the light-emitting layer;

[0028] The stacked structure containing the electron transport precursor layer and the cathode is processed under a second illumination condition to obtain a stacked structure containing the electron transport layer and the cathode.

[0029] Fifthly, this application also provides a method for fabricating a light-emitting device, wherein the light-emitting device has an inverted structure, and the fabrication method includes the following steps:

[0030] A cathode is provided, and an electron transport material layer is formed on one side of the cathode. The material of the electron transport material layer includes a compound as described in any one of the first aspects, or a compound prepared by any one of the preparation methods as described in the second aspect.

[0031] The electron transport material layer is treated with the first illumination condition to obtain the electron transport precursor layer;

[0032] A light-emitting layer is formed on the side of the electron transport precursor layer away from the cathode;

[0033] An anode is formed on the side of the light-emitting layer away from the electron transport precursor layer;

[0034] The stacked structure containing the electron transport precursor layer and the light-emitting layer is processed under a second illumination condition to obtain a stacked structure containing the electron transport layer and the light-emitting layer.

[0035] Sixthly, this application also provides a display device, the display device comprising a light-emitting device as described in any of the third aspects, or a light-emitting device prepared by any of the preparation methods described in any of the fourth or fifth aspects.

[0036] This application provides a compound, a light-emitting device, a method for preparing the same, and a display device, which have the following technical advantages:

[0037] The compound of this application has the structure shown in general formula (I), comprising a coumarin group with reversible photoresponsive properties and a nano-metal oxide. The metal atoms of the nano-metal oxide are coordinated with the double oxygen bonds of the coumarin group. After treatment under a first light irradiation condition, the compound can form a cross-linked structure, thereby exhibiting ideal anti-solvent properties. After treatment under a second light irradiation condition, the cross-linked structure de-crosslinks and re-forms the compound. Compared with the cross-linked structure, the compound has better carrier transport performance.

[0038] The light-emitting device of this application includes an electron transport layer. The material of the electron transport layer includes a compound represented by general formula (I), which makes the electron transport layer have ideal electronic conduction properties, which is beneficial to improving the photoelectric performance and lifespan of the light-emitting device.

[0039] The light-emitting device of this application includes the step of preparing an electron transport layer. In the process of preparing the electron transport layer, an electron transport material layer is first prepared, and then the electron transport material layer is treated with a first illumination condition to make the compound represented by general formula (I) in the electron transport material layer form a cross-linked compound to obtain an electron transport precursor layer. Then, an upper functional film is prepared on one side of the electron transport precursor layer. Since the cross-linked compound has better tolerance and stability than the compound represented by general formula (I), such as better solvent resistance and high temperature resistance, it can effectively avoid damage to the electron transport material by the raw materials (e.g., solvents) or the preparation process (e.g., high temperature) used to prepare the upper functional film. After the upper functional film is prepared, the electron transport precursor layer is treated with a second illumination condition to make the cross-linked compound de-crosslinked to form the compound represented by general formula (I). Since the compound represented by general formula (I) has better electron conductivity than the cross-linked compound, the overall performance of the light-emitting device is improved.

[0040] Applying the light-emitting device of this application or the light-emitting device prepared by the method of this application to a display device is beneficial to improving the display effect and service life of the display device. Attached Figure Description

[0041] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0042] Figure 1 This is a schematic flowchart illustrating a method for preparing a compound provided in an embodiment of this application.

[0043] Figure 2 This is a schematic diagram of the structure of the first light-emitting device provided in the embodiments of this application.

[0044] Figure 3 This is a schematic diagram of the structure of a second type of light-emitting device provided in an embodiment of this application.

[0045] Figure 4 This is a schematic diagram of the structure of a third type of light-emitting device provided in an embodiment of this application.

[0046] Figure 5 This is a schematic diagram of the structure of the fourth type of light-emitting device provided in the embodiments of this application.

[0047] Figure 6 This is a schematic diagram of the structure of the light-emitting device provided in Embodiment 1 of this application.

[0048] Figure 7 This is a schematic diagram of the structure of the light-emitting device provided in Embodiment 2 of this application.

[0049] Figure 8This is a schematic diagram of the structure of the light-emitting device provided in Embodiment 3 of this application.

[0050] Figure 9 This is a schematic diagram of the structure of the light-emitting device provided in Embodiment 4 of this application.

[0051] Figure 10 This is a schematic diagram of the structure of the light-emitting device provided in Embodiment 6 of this application. Detailed Implementation

[0052] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0054] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to," and the terms "a plurality of" or "multiple layers" mean two or more layers. Various embodiments of this application may exist in a range format; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; 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 digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0055] This application provides a compound having the structure shown in the general formula (Ⅰ):

[0056]

[0057] In general formula (I), R is selected from hydrogen atom, amino, carboxyl or hydrocarbon group, X is selected from nano metal oxide, and the metal atom of the nano metal oxide is coordinated with the double bond oxygen.

[0058] The compound represented by general formula (I) contains a coumarin group. Since the coumarin group has reversible photoresponse characteristics, the compound represented by general formula (I) also has reversible photoresponse characteristics. As shown in the reaction formula (III) below, two adjacent compound molecules can undergo chemical cross-linking under the first light irradiation condition (e.g., emitting ultraviolet light with a wavelength of 365 nm) to form a four-membered ring structure. It can be deduced that (N+1) compound molecules can undergo chemical cross-linking under the first light irradiation condition to form N four-membered ring structures, where N is a positive integer greater than or equal to 1. This allows (N+1) compound molecules to react and generate a cross-linked compound. Under the second light irradiation condition (e.g., emitting ultraviolet light with a wavelength of 254 nm), the cross-linked compound can dissociate to form the compound represented by general formula (I). The cross-linked compound has better tolerance (e.g., solvent resistance, high temperature resistance, etc.) than the compound represented by general formula (I), resulting in higher stability. However, the compound represented by general formula (I) has better carrier transport performance than the cross-linked compound.

[0059]

[0060] In some embodiments of this application, R is selected from hydrogen atoms.

[0061] As used in this application, "nanometallic oxide" refers to oxide semiconductor nanoparticles with electron transport capabilities, including but not limited to undoped and doped metal oxide nanoparticles. Doped metal oxide nanoparticles include a dopant element and a host metal element, which are not the same. The dopant element can be a metal or a non-metal, for example, selected from at least one of Al, Ga, Li, Cd, Cr, In, Cu, Fe, Mg, Sn, Sb, Ag, Ti, La, Nb, Mn, Zn, or Ce. The particle size of nanometal oxides can be, for example, from 2 nm to 15 nm. Furthermore, the surface of the nano-metal oxide may or may not be connected with ligands. The ligands include, but are not limited to, at least one of carboxylic acid ligands having 2 to 8 carbon atoms or amino ligands having 2 to 8 carbon atoms. The carboxylic acid ligands having 2 to 8 carbon atoms include, but are not limited to, at least one of acetate, propionic acid or acrylic acid. The amino ligands having 2 to 8 carbon atoms include, but are not limited to, at least one of ethanolamine, diethanolamine or diethylene glycolamine.

[0062] In some embodiments of this application, the nano metal oxide (X) is selected from at least one of nano ZnO, nano TiO2, nano SnO2, nano Ta2O3, nano ZrO2, nano TiLiO, nano ZnGaO, nano ZnAlO, nano ZnMgO, nano ZnSnO, nano ZnLiO, nano InSnO, nano AlZnO, nano ZnOCl, or nano ZnOF.

[0063] In some embodiments of this application, the compounds are selected from:

[0064]

[0065] This application also provides a method for preparing a compound, such as... Figure 1 As shown, the preparation method includes the following steps:

[0066] S1, Providing a mixture of the first compound and the second compound;

[0067] S2. Under an inert gas atmosphere, the mixture from step S1 is heat-treated to obtain the compound.

[0068] In step S1, the first compound has the structure shown in general formula (II):

[0069]

[0070] In general formula (II), R is selected from hydrogen atom, amino group, carboxyl group or hydrocarbon group.

[0071] In step S1, the second compound is selected from nano-metal oxides.

[0072] In step S2, "inert gas" refers to a type of gas that is chemically inert, does not react with the materials of each layer in the light-emitting device, and has the property of isolating oxygen and water, including but not limited to at least one of nitrogen, helium, neon, argon, krypton, or xenon. "Heat treatment" can be either isothermal heat treatment or non-isothermal heat treatment (e.g., temperature gradient change).

[0073] In one embodiment of this application, the first compound is coumarin, and the second compound is nano-ZnO. Step S1 includes: providing a nano-ZnO-ethanol solution (the concentration of nano-ZnO is 30 mg / mL), adding coumarin to the nano-ZnO-ethanol solution, mixing to obtain a mixture, wherein the mass ratio of the first compound to the second compound in the mixture is 1:3, and heat-treating at 120°C for 10 min under nitrogen atmosphere to obtain the compound shown in formula (1.1):

[0074]

[0075] In some embodiments of this application, in step S1, the mass ratio of the first compound to the second compound in the mixture is 1:(3-5). If the amount of the first compound added is too large, the reaction product obtained by heat treatment in step S2 will contain an excess of the first compound, and when the reaction product is used to prepare the electron transport layer, the effect on improving the electron conduction capability of the electron transport layer will be limited. If the amount of the first compound added is too small, the reaction product obtained by heat treatment in step S2 will contain an excess of the second compound, and when the reaction product is used to prepare the electron transport layer, the effect on improving the tolerance and stability of the electron transport layer will be limited.

[0076] It is understandable that a catalyst can be added to the mixture to increase the reaction rate and / or yield between the first and second compounds. However, heat treatment of the mixture containing only the first and second compounds can also produce the corresponding crosslinked compounds. Furthermore, a purification step can be added after step S2 to obtain a purified compound, but the compound obtained in step S2 can be directly used to prepare the electron transport layer of a light-emitting device.

[0077] This application also provides a light-emitting device, such as... Figure 2 As shown, the light-emitting device 1 includes an anode 11, a cathode 12, a light-emitting layer 13, and an electron transport layer 14. The anode 11 and cathode 12 are disposed opposite each other, the light-emitting layer 13 is disposed between the anode 11 and cathode 12, and the electron transport layer 14 is disposed between the light-emitting layer 13 and cathode 12. The material of the electron transport layer 14 includes any of the compounds described in the embodiments of this application or compounds prepared by any of the preparation methods described in the embodiments of this application, so that the electron transport layer 14 has ideal electron conduction ability. In the process of preparing the light-emitting device, the compounds in the electron transport layer 14 can be cross-linked by light irradiation treatment, thereby improving the tolerance and stability of the electron transport layer 14 and avoiding damage to the electron transport layer 14 by the raw materials and / or preparation processes of other functional films.

[0078] In the light-emitting device of this application embodiment, the materials of the anode 11 and the cathode 12 can be materials commonly used in the art. For example, the materials of the anode 11 and the cathode 12 are independently selected from at least one of metal, carbon material or metal oxide. The metal is selected from at least one of Al, Ag, Cu, Mo, Au, Ba, Ca or Mg; the carbon material is selected from at least one of graphite, carbon nanotube, graphene or carbon fiber; the metal oxide can be a doped or undoped metal oxide, for example, selected from at least one of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO) or magnesium-doped zinc oxide (MZO). The anode 11 or cathode 12 may also be selected from composite electrodes consisting of a metal sandwiched between doped or undoped transparent metal oxides. These composite electrodes include, but are not limited to, at least one of 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, ZnS / Al / ZnS, TiO2 / Ag / TiO2, or TiO2 / Al / TiO2. The thickness of the anode 11 may, for example, be from 40 nm to 160 nm, and the thickness of the cathode 12 may, for example, be from 20 nm to 120 nm.

[0079] In some embodiments of this application, the material of the light-emitting layer 13 is selected from organic light-emitting materials or quantum dots. The thickness of the light-emitting layer 13 can be, for example, 20 nm to 60 nm.

[0080] Organic light-emitting materials include, but are not limited to, at least one of diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent materials, TTPA fluorescent materials, TBRb fluorescent materials or DBP fluorescent materials.

[0081] Quantum dots include, but are not limited to, at least one of red, green, or blue quantum dots, and include, but are not limited to, at least one of single-component quantum dots, core-shell structured quantum dots, inorganic perovskite quantum dots, or organic-inorganic hybrid perovskite quantum dots. The particle size of quantum dots can be, for example, 5 nm to 10 nm.

[0082] For single-component quantum dots and core-shell structured quantum dots, the components of the quantum dots include, but are not limited to, at least one of group II-VI compounds, group III-V compounds, group IV-VI compounds, or group I-III-VI compounds, wherein the group II-VI compounds are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, and HgSTe. At least one of e, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, or HgZnSTe, wherein the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, In P, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNS b. At least one of InAlPAs or InAlPSb, wherein the IV-VI compound is selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, or SnPbSTe, and the I-III-VI compound is selected from at least one of CuInS2, CuInSe2, or AgInS2.

[0083] For inorganic perovskite quantum dots, the general structural formula is AMX3, where A is Cs. + Ions, where M is a divalent metal cation, and M includes, but is not limited to, Pb. 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co2+ Fe 2+ 、Ge 2+ Yb 2+ Or Eu 2+ X is a halide anion, including but not limited to Cl. - ,Br - Or I - .

[0084] For organic-inorganic hybrid perovskite quantum dots, the general structural formula is BMX3, where B is an organic amine cation, including but not limited to CH3(CH2). n -2NH 3+ (n≥2) or NH3(CH2) n NH3 2+ (n≥2), M is a divalent metal cation, and M includes, but is not limited to, Pb. 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Or Eu 2+ X is a halide anion, including but not limited to Cl. - ,Br - Or I - .

[0085] To achieve better photoelectric performance and lifespan, in some embodiments of this application, such as... Figure 3 As shown, in Figure 2 Based on the light-emitting device shown, the light-emitting device 1 further includes a hole functional layer 15, which is disposed between the anode 11 and the light-emitting layer 13. The hole functional layer includes, but is not limited to, at least one of a hole transport layer or a hole injection layer. In one embodiment of this application, the hole functional layer includes a stacked hole injection layer and a hole transport layer, with the hole injection layer disposed between the anode and the light-emitting layer, and the hole transport layer disposed between the hole injection layer and the light-emitting layer. The thickness of the hole functional layer 15 can be, for example, from 20 nm to 100 nm.

[0086] Materials used in hole transport layers include, but are not limited to, poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB, CAS No. 220797-16-0), 3-hexyl-substituted polythiophene (CAS No. 104934-50-1), poly(9-vinylcarbazole) (PVK, CAS No. 25067-59-8), poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly-TPD, CAS No. 472960-35-3), poly(N,N'-bis(4-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine-CO-9,9-dioctylfluorene) (PFB, CAS No. 223569-28-6), and 4,4',4”-tris(carbazole-9-yl)triphenylamine (abbreviated as...). The hole transport layer is selected from at least one of the following: TCTA (CAS No. 139092-78-7), 4,4'-bis(9-carbazole)biphenyl (CBP, CAS No. 58328-31-7), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD, CAS No. 65181-78-4), or N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB, CAS No. 123847-85-8). Furthermore, the hole transport layer material can also be selected from inorganic materials with hole transport capabilities, including but not limited to at least one of NiO, WO3, MoO3, and CuO. The thickness of the hole transport layer can be, for example, from 10 nm to 50 nm.

[0087] The hole injection layer material includes, but is not limited to, poly(3,4-vinyldioxythiophene): poly(styrene sulfonic acid) (CAS No. 155090-83-8), copper phthalocyanine (CuPc, CAS No. 147-14-8), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4-TCNQ, CAS No. 29261-33-4), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HATCN, CAS No. 105598-27-4), transition metal oxides, or transition metal chalcogenides, wherein the transition metal oxide may be NiO. x MoO x WO x or CrO x One or more of the following, the metal chalcogenide compounds may be MoS x MoSe x WS x 、WSe xOr one or more of CuS. The thickness of the hole injection layer can be, for example, 10 nm to 50 nm.

[0088] It should be noted that the light-emitting device in the embodiments of this application may also include other layer structures. For example, the light-emitting device may also include an electron injection layer, which is disposed between the electron transport layer and the cathode. The material of the electron injection layer includes, but is not limited to, at least one of alkali metal halides, alkali metal organo-complexes, or organophosphorus compounds. Alkali metal halides include, but are not limited to, LiF. Alkali metal organo-complexes include, but are not limited to, lithium 8-hydroxyquinoline. Organophosphorus compounds include, but are not limited to, at least one of organophosphorus oxides, organothiophosphorus compounds, or organoselenophosphorus compounds.

[0089] In order to improve the electrical performance of the light-emitting device, in some embodiments of this application, the electron transport layer is provided with a rough structure on the side near the cathode, so that an ohmic contact can be formed between the electron transport layer and the cathode more easily, thereby reducing the potential barrier for electron injection.

[0090] As used in this application, "rough structure" refers to any structure that can improve the roughness of the side of the electron transport layer near the cathode, including but not limited to grooves and / or protrusions formed on the side of the electron transport layer near the cathode, such as sawtooth, wavy, etc. The shape, number and size of the rough structure are not specifically limited.

[0091] To further improve the overall performance of the light-emitting device, in some embodiments of this application, such as... Figure 4 As shown in the figure Figure 2 Based on the light-emitting device shown, the electron transport layer 14 of the light-emitting device 1 includes a first electron transport sublayer 141 and a second electron transport sublayer 142. The first electron transport sublayer 141 is disposed between the light-emitting layer 13 and the cathode 12, and the second electron transport sublayer 142 is disposed between the first electron transport sublayer 141 and the cathode 12. The side of the second electron transport sublayer 142 near the cathode 12 has a rough structure 100. The material of the first electron transport sublayer 141 includes any of the compounds described in the embodiments of this application, or compounds prepared by any of the preparation methods described in the embodiments of this application. The material of the second electron transport sublayer 142 includes any of the compounds described in the embodiments of this application, or compounds prepared by any of the preparation methods described in the embodiments of this application, or nano-metal oxides.

[0092] To achieve an ohmic contact between the electron transport layer and the cathode while maximizing the surface flatness of the electron transport layer to further improve the overall performance of the light-emitting device, in some embodiments of this application, such as... Figure 5 As shown, compared to Figure 4 The light-emitting device shown, Figure 5 The distinguishing technical features of the light-emitting device shown are only as follows: the light-emitting device 1 is an upright structure, and the light-emitting device 1 is provided with a light-emitting area 101 and a non-light-emitting area 102. The stacked structure of the light-emitting area 101 includes an anode 11, a light-emitting layer 13, an electron transport layer 14 and a cathode 12 stacked in sequence. The stacked structure of the non-light-emitting area 102 includes a light-emitting layer 13, an electron transport layer 14 and a cathode 12 stacked in sequence, and the non-light-emitting area 102 does not have an anode 11. The electron transport layer 14 includes a first electron transport sublayer 141 and a second electron transport sublayer 142 stacked in sequence. The first electron transport sublayer 141 is disposed between the light-emitting layer 13 and the cathode 12, and the second electron transport sublayer 142 is disposed between the first electron transport sublayer 141 and the cathode 12. A rough structure 100 is disposed on the side of the second electron transport sublayer 142 near the cathode 12, and the rough structure 100 is located in the light-emitting area 101, thereby effectively improving the electron injection efficiency and improving the surface flatness of the electron transport layer.

[0093] In some embodiments of this application, the thickness ratio of the first electron transport sublayer to the second electron transport sublayer is 1:(0.5~1). In one embodiment of this application, the overall thickness of the electron transport layer is 40nm to 50nm, the overall thickness of the first electron transport sublayer is 20nm to 30nm, and the thickness of the second electron transport sublayer is 10nm to 20nm. Both excessively thick and excessively thin first electron transport sublayers have limited effect on improving the overall performance of the light-emitting device. If the thickness of the first electron transport sublayer is too thin, the improvement in the tolerance and stability of the electron transport layer is limited; if the thickness of the first electron transport sublayer is too thick, the improvement in the electron conduction capability of the electron transport layer is limited.

[0094] It should be noted that directly doping coumarin into the electron transport layer has a relatively weak impact on the overall crosslinking properties of the film. To improve the reversible photocrosslinking characteristics of the film, a large amount of coumarin is often required, which leads to a decrease in the conductivity of the electron transport layer, resulting in a decrease in electron mobility and consequently adversely affecting the photoelectric performance and lifespan of the light-emitting device. In the embodiments of this application, the material of the electron transport layer includes the compound shown in general formula (I). Compared with the film prepared by blending nano-metal oxides and coumarin, the film prepared by the compound shown in general formula (I) has significantly improved stability and durability.

[0095] This application also provides a method for fabricating a light-emitting device, mainly applicable to the fabrication of an electroluminescent diode with a positive-position structure. The fabrication method includes the following steps:

[0096] S11. Provide an anode and prepare a light-emitting layer on one side of the anode;

[0097] S12. An electron transport material layer is formed on the side of the light-emitting layer away from the anode in step S11. The material of the electron transport material layer includes any of the compounds described in the embodiments of this application, or compounds prepared by any of the preparation methods described in the embodiments of this application.

[0098] S13. The electron transport material layer of step S12 is processed under the first illumination condition to obtain the electron transport precursor layer.

[0099] S14. A cathode is formed on the side of the electron transport precursor layer away from the light-emitting layer in step S13;

[0100] S15. The stacked structure containing the electron transport precursor layer and the cathode is processed under the second illumination condition to obtain the stacked structure containing the electron transport layer and the cathode.

[0101] Specifically, the electron transport material layer is prepared using a solution method, and the cathode is prepared using methods including, but not limited to, deposition and solution methods. Solution methods include, but are not limited to, spin coating, coating, inkjet printing, blade coating, dip-coating, immersion, spraying, roller coating, or casting. After obtaining a wet film using the solution method, a drying process is required. The drying process includes all processes that can enable the wet film to obtain higher energy and transform into a dry film; the drying process can be, for example, heat treatment. Deposition methods include chemical and physical methods. Chemical methods include, but are not limited to, chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, or co-precipitation. Physical methods include, but are not limited to, thermal evaporation deposition, electron beam evaporation deposition, magnetron sputtering, multi-arc ion plating, physical vapor deposition, atomic layer deposition, or pulsed laser deposition.

[0102] In step S11, the light-emitting layer can be formed directly on one side of the anode, or it can be formed indirectly on one side of the anode. That is, firstly, a functional thin film that promotes electron-hole transport balance is formed on one side of the anode using a solution method or deposition method, and then the light-emitting layer is formed on the side of the functional thin film away from the anode. For example, a hole injection layer is first formed on one side of the anode using a solution method or deposition method, then a hole transport layer is formed on the side of the hole injection layer away from the anode, and then the light-emitting layer is formed on the side of the hole transport layer away from the hole injection layer.

[0103] In step S13, the light source for the first illumination condition is ultraviolet light emitting wavelengths of 363 nm to 367 nm. In one embodiment of this application, the light source for the first illumination condition is an ultraviolet laser emitting wavelengths of 365 nm, with a pulse width of 22 ns, a power of 5 W, a frequency of 1.2 Hz, and a duration of 90 s. After treatment under the first illumination condition, the compound in the electron transport material layer, as shown in general formula (I), forms a cross-linked compound. The cross-linked compound has better tolerance and stability. Therefore, when preparing other functional thin films on the side of the electron transport precursor layer away from the light-emitting layer, damage to the electron transport precursor layer can be avoided by the raw materials (e.g., solvents) or preparation processes (e.g., high temperatures) used to prepare other functional thin films. For example, when preparing a cathode on the side of the electron transport precursor layer away from the light-emitting layer using vapor deposition or sputtering, the cross-linked compound has ideal high-temperature resistance, thus effectively improving the adverse effects of the high-temperature conditions required by vapor deposition or sputtering on the electron transport precursor layer.

[0104] In step S14, a cathode can be formed directly on the side of the electron transport precursor layer away from the light-emitting layer, or indirectly on the side of the electron transport precursor layer away from the light-emitting layer. For example, other functional films that promote electron-hole transport balance (such as an electron injection layer) can be formed on the side of the electron transport precursor layer away from the light-emitting layer using a solution method or deposition method, and then a cathode can be formed.

[0105] In step S15, after being treated with the second illumination condition, the cross-linked compound in the electron transport precursor layer undergoes photode-crosslinking, and the de-crosslinking forms a compound as shown in general formula (I), so as to improve the electron conduction capability of the electron transport layer, thereby improving the overall performance of the light-emitting device.

[0106] In some embodiments of this application, the light source for the second illumination condition is ultraviolet light emitting wavelengths from 252 nm to 256 nm. In one embodiment of this application, the light source for the second illumination condition is an ultraviolet laser emitting wavelengths from 254 nm, with a pulse width of 22 ns, a power of 5 W, a frequency of 1.2 Hz, and a duration of 90 s.

[0107] It should be noted that the order of steps S14 and S15 is not specifically limited. They can be implemented either by first step S14 and then step S15, or by first step S15 and then step S14. Furthermore, other steps can be added between steps S14 and S15, as long as the following condition is met: other functional thin films must be prepared on the electron transport precursor layer first, and then the second illumination condition treatment can be performed. The second illumination condition treatment cannot be performed on the electron transport precursor layer immediately after it is prepared.

[0108] In one embodiment of this application, the method for fabricating the light-emitting device includes the following steps:

[0109] S101, Provide an anode, and prepare a light-emitting layer on one side of the anode;

[0110] S102. An electron transport material layer is formed on the side of the light-emitting layer away from the anode in step S101. The material of the electron transport material layer includes any of the compounds described in the embodiments of this application, or compounds prepared by any of the preparation methods described in the embodiments of this application.

[0111] S103. The electron transport material layer of step S102 is processed under the first illumination condition to obtain the electron transport precursor layer.

[0112] S104. A second electron transport sublayer is formed on the side of the electron transport precursor layer away from the light-emitting layer in step S103. The material of the second electron transport sublayer includes nano-metal oxide.

[0113] S105. A rough structure is formed on the side of the second electron transport sublayer away from the electron transport precursor layer. The method for preparing the rough structure includes, but is not limited to, at least one of hydrogen ion implantation, acid treatment, alkali treatment or low temperature treatment.

[0114] S106. The electron transport precursor layer is processed with the second illumination condition to obtain the first electron transport sublayer, and an electron transport layer containing the first electron transport sublayer and the second electron transport sublayer is obtained.

[0115] S107. A cathode is formed on the side of the electron transport layer away from the light-emitting layer in step S106.

[0116] In another embodiment of this application, the method for fabricating the light-emitting device includes the following steps:

[0117] S201. A light-emitting layer is formed on one side of the anode;

[0118] S202. A first electron transport material layer is formed on the side of the light-emitting layer away from the anode in step S201. The material of the first electron transport material layer includes any of the compounds described in the embodiments of this application, or compounds prepared by any of the preparation methods described in the embodiments of this application.

[0119] S203. The first electron transport material layer of step S202 is processed under the first illumination condition to obtain the first electron transport precursor layer.

[0120] S204. A second electron transport material layer is formed on the side of the first electron transport precursor layer away from the light-emitting layer. The material of the second electron transport material layer includes any of the compounds described in the embodiments of this application, or compounds prepared by any of the preparation methods described in the embodiments of this application.

[0121] S205. The second electron transport material layer has a light-emitting region and a non-light-emitting region. The light-emitting region is treated with a second illumination condition to obtain the second electron transport precursor sublayer.

[0122] S206. A rough structure is formed on the side of the second electron transport precursor sublayer away from the first electron transport precursor sublayer. The method for preparing the rough structure includes, but is not limited to, at least one of hydrogen ion implantation, acid treatment, alkali treatment or low temperature treatment, and the rough structure is located in the light-emitting region.

[0123] S207, In step S207, a cathode is formed on the side of the second electron transport precursor layer away from the first electron transport precursor layer;

[0124] S208. The first electron transport precursor sublayer and the second electron transport precursor sublayer are processed under the second illumination conditions to obtain an electron transport layer containing the first electron transport sublayer and the second electron transport sublayer.

[0125] This application also provides a method for fabricating a light-emitting device, mainly applicable to fabricating light-emitting devices with an inverted structure. The fabrication method includes the following steps:

[0126] S11' An electron transport material layer is formed on one side of the cathode. The material of the electron transport material layer includes any of the compounds described in any of the embodiments of this application, or compounds prepared by any of the preparation methods described in any of the embodiments of this application.

[0127] S12': The electron transport material layer in step S11' is processed under the first illumination condition to obtain the electron transport precursor layer;

[0128] S13', A light-emitting layer is formed on the side of the electron transport precursor layer away from the cathode in step S12';

[0129] S14', An anode is formed on the side of the light-emitting layer away from the electron transport precursor layer in step S13';

[0130] S15'. The stacked structure containing the electron transport precursor layer and the light-emitting layer is processed under the second illumination condition to obtain a stacked structure containing the electron transport layer and the light-emitting layer.

[0131] It should be noted that the anode preparation methods described above include, but are not limited to, deposition and solution methods, as explained above. Furthermore, the first illumination conditions in step S12' and the second illumination conditions in step S15' are as explained above.

[0132] In step S11', an electron transport material layer can be formed directly on one side of the cathode, or it can be formed indirectly on one side of the cathode. For example, other functional thin films (such as an electron injection layer) can be formed on one side of the cathode first by solution method or deposition method, and then the electron transport layer can be formed.

[0133] Similarly, in step S13', the light-emitting layer can be directly formed on the side of the electron transport precursor layer away from the cathode, or indirectly formed on the side of the electron transport precursor layer away from the cathode; in step S14', the anode can be directly formed on the side of the light-emitting layer away from the electron transport precursor layer, or indirectly formed on the side of the light-emitting layer away from the electron transport precursor layer.

[0134] It should be noted that the order of each step in the above preparation method is not specifically limited, but only needs to meet the following conditions: after at least one functional thin film is formed on the side of the electron transport precursor layer away from the cathode, the second light irradiation treatment is performed. The electron transport precursor layer cannot be subjected to the second light irradiation treatment immediately after the electron transport precursor layer is prepared.

[0135] Compounds prepared using the compounds of the embodiments of this application or the preparation methods of the embodiments of this application, when used as electron transport materials for light-emitting devices, have advantages such as ideal solution processing characteristics and mild conditions for cross-linking reaction (no need for high-temperature cross-linking and the addition of photosensitizers), which helps to reduce the manufacturing cost of light-emitting devices.

[0136] This application also provides a display device, including any of the light-emitting devices described in this application or a light-emitting device prepared by any of the methods described in this application. The display device can be any electronic product with display functionality, 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. Smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0137] The technical solutions and effects of this application will be described in detail below through specific embodiments, comparative examples and experimental examples. The following embodiments are only some embodiments of this application and are not intended to limit this application.

[0138] Example 1

[0139] This embodiment provides a light-emitting device and its fabrication method. The light-emitting device in this embodiment is a quantum dot light-emitting diode with a positive-position structure, such as... Figure 6 As shown, in the direction from bottom to top, the light-emitting device 1 includes a substrate 10, an anode 11, a hole injection layer 151, a hole transport layer 152, a light-emitting layer 13, an electron transport layer 14, and a cathode 12 arranged sequentially. The light-emitting device 1 has a light-emitting region 101 and a non-light-emitting region 102. The stacked structure of the light-emitting region 101 includes the anode 11, hole injection layer 151, hole transport layer 152, light-emitting layer 13, electron transport layer 14, and cathode 12 arranged sequentially. The stacked structure of the non-light-emitting region 102 includes the hole injection layer 151, hole transport layer 152, light-emitting layer 13, electron transport layer 14, and cathode 12 arranged sequentially. The non-light-emitting region 102 does not have an anode 11.

[0140] The materials and thicknesses of each layer in the light-emitting device of this embodiment are as follows:

[0141] The substrate 10 is made of glass and has a thickness of 20 mm;

[0142] Anode 11 is made of ITO and has a thickness of 15 nm.

[0143] The cathode 12 is made of silver and has a thickness of 35 nm.

[0144] The material of the light-emitting layer 13 is ZnS quantum dots, with an emission wavelength of 631 nm, a peak width of 19.5 nm, and a thickness of 23 nm;

[0145] The electron transport layer 14 is made of the compound shown in formula (1.1) and has a thickness of 40 nm;

[0146] The hole injection layer 151 is made of PEDOT:PSS and has a thickness of 20nm.

[0147] The hole transport layer 152 is made of TFB material and has a thickness of 20nm;

[0148] The fabrication method of the light-emitting device in this embodiment includes the following steps:

[0149] S1.1 Provide a substrate containing an anode (ITO), and spin-coat a PEDOT-PSS aqueous solution (CAS No. 155090-83-8, purchased from Sigma-Aldrich) on the side of the anode away from the substrate under normal temperature and pressure. Then, heat-treat at 150°C for 15 min and let it stand to cool for 5 min to obtain a hole injection layer.

[0150] S1.2 Under a nitrogen atmosphere at normal temperature and pressure (H2O and O2 content less than 5ppm), spin-coat the side of the hole injection layer away from the anode in step S1.1 with a TFB-chlorobenzene solution of 8mg / mL, then heat-treat at 80℃ for 10min, and let it stand and cool for 5min to obtain the hole transport layer.

[0151] S1.3 Under a nitrogen atmosphere at normal temperature and pressure (H2O and O2 content less than 5ppm), spin-coat a ZnS-n-octane solution with a concentration of 20mg / mL on the side of the hole transport layer away from the hole injection layer in step S1.2, then heat-treat at 80℃ for 10min, and let it stand and cool for 5min to obtain the light-emitting layer.

[0152] S1.4. Provide a nano ZnO (particle size 10 nm)-ethanol solution with a concentration of 30 mg / mL, add coumarin powder to it, and mix to obtain a mixture. In the mixture, the mass ratio of nano ZnO to coumarin is 3:1. Heat-treat at 120 °C for 10 min under nitrogen atmosphere to obtain the compound shown in formula (1.1). Spin-coat the compound shown in formula (1.1) on the side of the light-emitting layer away from the hole transport layer, and then heat-treat at 80 °C for 10 min and let it stand and cool for 5 min to obtain the electron transport material layer.

[0153] S1.5. The electron transport material layer is treated with the first illumination condition to obtain the electron transport precursor layer. The first illumination condition is: the light source is an ultraviolet laser with an emission wavelength of 365nm, the pulse width of the ultraviolet laser is 22ns, the power is 5W, the frequency is 1.2Hz, and the duration is 90s.

[0154] S1.6, with a vacuum degree not exceeding 3×10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the electron transport precursor layer away from the light-emitting layer to obtain the cathode.

[0155] S1.7. The electron transport precursor layer is processed using the second illumination condition to obtain the electron transport layer. The second illumination condition is as follows: the light source is an ultraviolet laser with an emission wavelength of 254nm, the pulse width of the ultraviolet laser is 22ns, the power is 5W, the frequency is 1.2Hz, and the duration is 90s. Then, the light-emitting device is obtained by encapsulation.

[0156] Example 2

[0157] This embodiment provides a light-emitting device and its fabrication method. Compared with the light-emitting device of Embodiment 1, the only difference between the light-emitting device of this embodiment and the one described is that: Figure 7 As shown, in Figure 6 Based on the light-emitting device shown, the electron transport layer 14 has a rough structure 100 on the side near the cathode 12.

[0158] Compared with the preparation method of Example 1, the difference in the preparation method of this example is only that: after step S1.5 and before step S1.6, the step of "placing the multilayer structure containing the electron transport precursor layer obtained in step S1.5 in an acrylic acid atmosphere of 800ppm and performing acid treatment for 1 hour" is added.

[0159] Example 3

[0160] This embodiment provides a light-emitting device and its fabrication method. The light-emitting device in this embodiment is a quantum dot light-emitting diode with a positive-position structure, such as... Figure 8 As shown, from bottom to top, the light-emitting device includes a substrate 10, an anode 11, a hole injection layer 151, a hole transport layer 152, a light-emitting layer 13, an electron transport layer 14, and a cathode 12 arranged sequentially. The electron transport layer 14 is composed of a first electron transport sublayer 141 and a second electron transport sublayer 142 stacked together. The first electron transport sublayer 141 is disposed between the light-emitting layer 13 and the cathode 12, and the second electron transport sublayer 142 is disposed between the first electron transport sublayer 141 and the cathode 12. The light-emitting device 1 has a light-emitting area. The light-emitting region 101 includes an anode 11, a hole injection layer 151, a hole transport layer 152, a light-emitting layer 13, a first electron transport sublayer 141, a second electron transport sublayer 142, and a cathode 12, which are stacked sequentially. The non-light-emitting region 102 also includes a hole injection layer 151, a hole transport layer 152, a light-emitting layer 13, a first electron transport sublayer 141, a second electron transport sublayer 142, and a cathode 12, which are stacked sequentially. The non-light-emitting region 102 does not have an anode 11.

[0161] Except for electron transport layer 14, the materials and thicknesses of the other layers in the light-emitting device of this embodiment are the same as those in Embodiment 1. For electron transport layer 14, the material of the first electron transport sublayer 141 includes the compound shown in formula (1.1) and the thickness is 30 nm; the material of the second electron transport sublayer 142 is nano-ZnO with a particle size of 10 nm and a thickness of 10 nm.

[0162] The fabrication method of the light-emitting device in this embodiment includes the following steps:

[0163] S3.1, Refer to step S1.1;

[0164] S3.2, Refer to step S1.2;

[0165] S3.3, Refer to step S1.3;

[0166] S3.4, Refer to step S1.4;

[0167] S3.5, Refer to step S1.5;

[0168] S3.6. Spin-coat the side of the electron transport precursor layer obtained in step S3.5 away from the light-emitting layer with a concentration of 30 mg / mL of nano ZnO (particle size of 10 nm)-ethanol solution, then heat-treat at 80 °C for 20 min, and let it stand and cool for 5 min to obtain the second electron transport sublayer.

[0169] S3.7, with a vacuum degree not exceeding 3×10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the second electron transport sublayer away from the electron transport precursor layer to obtain the cathode.

[0170] S3.8. The electron transport precursor layer is processed under the second illumination condition to obtain the first electron transport sublayer. The second illumination condition is the same as in Example 1. Then, the light-emitting device is obtained by encapsulation.

[0171] Example 4

[0172] This embodiment provides a light-emitting device and its fabrication method. Compared with the light-emitting device of Embodiment 3, the only difference between the light-emitting device of this embodiment and that of Embodiment 3 is: Figure 9 As shown, in Figure 8 Based on the light-emitting device shown, the second electron transport sublayer 142 has a rough structure 100 on the side near the cathode 12.

[0173] Compared with the preparation method of Example 3, the difference in the preparation method of this example is only that: after step S3.6 and before step S3.7, the step of "placing the stacked structure containing the electron transport precursor layer and the second electron transport sublayer obtained in step S3.6 in an acrylic acid atmosphere of 800ppm and performing acid treatment for 1h" is added.

[0174] Example 5

[0175] This embodiment provides a light-emitting device and its preparation method. Compared with the light-emitting device of Embodiment 3, the only difference of the light-emitting device in this embodiment is that the material of the second electron transport sublayer 142 is replaced by "nano ZnO with a particle size of 10 nm" with "a compound including the one shown in formula (1.1)".

[0176] The fabrication method of the light-emitting device in this embodiment includes the following steps:

[0177] S5.1, Refer to step S1.1;

[0178] S5.2, Refer to step S1.2;

[0179] S5.3, Refer to step S1.3;

[0180] S5.4, Refer to step S1.4;

[0181] S5.5. Referring to step S1.5, obtain the first electron transport precursor sublayer;

[0182] S5.6. Provide a nano ZnO (particle size 10 nm)-ethanol solution with a concentration of 30 mg / mL, add coumarin powder to it, mix to obtain a mixture, in which the mass ratio of nano ZnO to coumarin is 3:1, heat treat at 120°C for 10 min under nitrogen atmosphere to obtain the compound shown in formula (1.1), spin coat the compound shown in formula (1.1) on the side of the first electron transport precursor layer away from the light-emitting layer, then heat treat at 80°C for 10 min, and let it stand and cool for 5 min to obtain the second electron transport material layer;

[0183] S5.7. The second electron transport material layer is treated with the first illumination condition to obtain the second electron transport precursor sublayer. The first illumination condition is the same as in Example 1.

[0184] S5.8, with a vacuum degree not exceeding 3×10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the second electron transport precursor layer away from the first electron transport precursor layer to obtain a cathode.

[0185] S5.9. The first electron transport precursor layer and the second electron transport precursor layer are treated with the second illumination conditions (the same as in Example 1) to obtain an electron transport layer containing the first electron transport layer and the second electron transport layer, and then packaged to obtain a light-emitting device.

[0186] Example 6

[0187] This embodiment provides a light-emitting device and its fabrication method. Compared with the light-emitting device of Embodiment 3, the only difference between the light-emitting device of this embodiment and that of Embodiment 3 is: Figure 10 As shown, the material of the second electron transport sublayer 142 is replaced by "nano ZnO with a particle size of 10 nm" with "a compound including the one shown in formula (1.1)", and the second electron transport sublayer 142 is provided with a rough structure 100 on the side near the cathode 12, and the rough structure 100 is located in the light-emitting region.

[0188] Except for electron transport layer 14, the materials and thicknesses of the other layers in the light-emitting device are the same as in Example 1.

[0189] The fabrication method of the light-emitting device in this embodiment includes the following steps:

[0190] S6.1, refer to S1.1;

[0191] S6.2, refer to S1.2;

[0192] S6.3, refer to S1.3;

[0193] S6.4. Provide a nano ZnO (particle size 10 nm)-ethanol solution with a concentration of 30 mg / mL, add coumarin powder to it, mix to obtain a mixture, in which the mass ratio of nano ZnO to coumarin is 3:1, heat treat at 120°C for 10 min under nitrogen atmosphere to obtain the compound shown in formula (1.1), spin coat the compound shown in formula (1.1) on the side of the light-emitting layer away from the hole transport layer, then heat treat at 80°C for 10 min, and let it stand and cool for 5 min to obtain the first electron transport material layer;

[0194] S6.5. The first electron transport material layer is treated with the first illumination condition to obtain the first electron transport precursor sublayer, wherein the first illumination condition is the same as in Example 1.

[0195] S6.6 Spin-coat the compound shown in formula (1.1) on the side of the first electron transport precursor layer away from the light-emitting layer (preparation method refers to step S6.4), then heat-treat at 80°C for 10 min, and let it stand and cool for 5 min to obtain the second electron transport material layer.

[0196] S6.7 and S6.6 The second electron transport material layer has a light-emitting region and a non-light-emitting region. The light-emitting region is treated with the second illumination condition (the same as in Example 1) to obtain the second electron transport precursor sublayer.

[0197] S6.8. The laminated structure containing the first electron transport precursor sublayer and the second electron transport precursor sublayer obtained in step S6.7 is placed in an acrylic acid atmosphere of 800 ppm and subjected to acid treatment for 1 hour.

[0198] S6.9, with a vacuum degree not exceeding 3×10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the second electron transport precursor layer away from the first electron transport precursor layer to obtain a cathode.

[0199] S6.10. The first electron transport precursor layer and the second electron transport precursor layer are treated with the second illumination conditions (the same as in Example 1) to obtain an electron transport layer containing the first electron transport layer and the second electron transport layer, and then packaged to obtain a light-emitting device.

[0200] Comparative Example 1

[0201] This comparative example provides a light-emitting device and its preparation method. Compared with the light-emitting device of Example 1, the only difference of the light-emitting device of this comparative example is that the material of the electron transport layer is nano-ZnO with a particle size of 10nm.

[0202] Compared to the preparation method of Example 1, the difference in the preparation method of this comparative example is only that: steps S1.5 and S1.7 are omitted, and step S1.4 is replaced with "spin-coating a 30 mg / mL nano-ZnO (particle size 10 nm)-ethanol solution on the side of the light-emitting layer away from the hole transport layer, then heat-treating at 80°C for 10 min, and allowing it to cool for 5 min to obtain the electron transport layer", and step S1.6 is replaced with "under a vacuum degree not exceeding 3 × 10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the electron transport layer away from the light-emitting layer to obtain the cathode.

[0203] Comparative Example 2

[0204] This comparative example provides a light-emitting device and its preparation method. Compared with the light-emitting device of Example 1, the only difference of the light-emitting device of this comparative example is that the material of the electron transport layer is nano-ZnO with a particle size of 10nm, and a rough structure is provided on the side of the electron transport layer near the cathode.

[0205] Compared to the preparation method of Example 1, the difference in the preparation method of this comparative example is only that: steps S1.5 and S1.7 are omitted, and step S1.4 is replaced with "spin-coating a 30 mg / mL nano-ZnO (particle size 10 nm)-ethanol solution on the side of the light-emitting layer away from the hole transport layer, then heat-treating at 80°C for 10 min, and allowing it to cool for 5 min to obtain the electron transport layer", and step S1.6 is replaced with "under a vacuum degree not exceeding 3 × 10 -4 "In a nitrogen atmosphere of Pa, silver is vacuum-deposited on the side of the electron transport layer away from the light-emitting layer to obtain a cathode", and after the replacement step S1.4 and before step S1.6, the step "the multilayer structure containing the electron transport layer obtained in step S1.4 is placed in an acrylic atmosphere of 800 ppm and acid-treated for 1 hour" is added.

[0206] Comparative Example 3

[0207] This comparative example provides a light-emitting device and its preparation method. Compared with the light-emitting device of Example 1, the only difference of the light-emitting device of this comparative example is that the material of the electron transport layer is composed of coumarin and nano-ZnO with a particle size of 10 nm, wherein the mass ratio of coumarin to nano-ZnO is 1:3.

[0208] The preparation method of this comparative example includes the following steps:

[0209] S10.1, Refer to step S1.1;

[0210] S10.2, Refer to step S1.2;

[0211] S10.3, Refer to step S1.3;

[0212] S10.4. Provide a 30 mg / mL nano ZnO (particle size 10 nm)-ethanol solution, add coumarin powder to it, and mix to obtain a mixture. In the mixture, the mass ratio of nano ZnO to coumarin is 3:1. Spin-coat the mixture onto the side of the light-emitting layer away from the hole transport layer, then heat-treat at 80°C for 10 min, and let it stand and cool for 5 min to obtain the electron transport layer.

[0213] S10.5, with a vacuum degree not exceeding 3×10 -4 In a nitrogen atmosphere at Pa, silver is vacuum-deposited on the side of the electron transport layer away from the light-emitting layer to obtain a cathode, which is then packaged to obtain a light-emitting device.

[0214] Test case

[0215] Performance tests were conducted on the light-emitting devices of Examples 1 to 6 and Comparative Examples 1 to 3. A Fostec FPD optical characteristic measurement system (an efficiency testing system built using a LabVIEW-controlled QE-PRO spectrometer, Keithley 2400, and Keithley 6485) was used to detect parameters such as voltage, current, brightness, and emission spectrum of each light-emitting device. Key parameters such as external quantum dot efficiency and power efficiency were then calculated. A lifetime testing device (purchased from Jinghe) was used to test the lifetime of each light-emitting device. The performance test item was: under a constant current drive condition of 2mA, the brightness (L, cd / m²) of the light-emitting device. 2 The time required for the brightness of a light-emitting device to decay from 100% to 95% (T95,h), and the maximum external quantum efficiency (EQE) of the light-emitting device. max The performance test results are detailed in Table 1 below: (1000 nits) and the current efficiency of the light-emitting device (CE, cd / A); and the time required for the brightness of the light-emitting device to decay from 100% to 95% (T95-1K, h) and the current efficiency of the light-emitting device (CE-1K, cd / A).

[0216] Table 1 shows the performance test results of the light-emitting devices in Examples 1 to 6 and Comparative Examples 1 to 3.

[0217]

[0218] As shown in Table 1, compared with the light-emitting devices of Comparative Examples 1 to 3, the light-emitting devices of Examples 1 to 6 have significant advantages in overall performance. Among them, the light-emitting device of Example 6 has the best overall performance. This indicates that the electron transport layer of the light-emitting device contains the compound shown in general formula (Ⅰ), which is beneficial to improving the photoelectric performance and service life of the light-emitting device.

[0219] As can be seen from Examples 1 and 2, Examples 3 and 4, and Examples 5 and 6, setting a rough structure on the side of the electron transport layer near the cathode can enable an ohmic contact to be formed between the electron transport layer and the cathode, thereby reducing the potential barrier for electron injection and further improving the overall performance of the light-emitting device.

[0220] The overall performance of the light-emitting device in Example 6 is significantly better than that of the light-emitting devices in other examples and comparative examples. This is because: not only is an ohmic contact formed between the electron transport layer and the cathode, but also the surface flatness of the electron transport layer is improved as much as possible by setting a rough structure in the light-emitting area and not setting a rough structure in the non-light-emitting area, thereby further improving the overall performance of the light-emitting device.

[0221] Furthermore, as can be seen from Examples 1 to 6 and Comparative Example 3, compared with the electron transport layer prepared by the blend of nano-metal oxide and coumarin, the electron transport layer prepared by the compound represented by general formula (I) has better stability and tolerance, which is more conducive to improving the overall performance of the light-emitting device.

[0222] The foregoing has provided a detailed description of a compound, a light-emitting device, a method for preparing the same, and a display device, as provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A light-emitting device, characterized in that, include: anode; The cathode is disposed opposite to the anode; A light-emitting layer is disposed between the anode and the cathode; as well as An electron transport layer is disposed between the light-emitting layer and the cathode; The electron transport layer has a rough structure on the side closest to the cathode; The electron transport layer is made of a compound having the structure shown in general formula (I): (Ⅰ) Wherein, X is selected from nano ZnO, and the metal atoms of the nano ZnO are coordinated with double-bonded oxygen, and the particle size of the nano ZnO is 2 nm to 15 nm. R is selected from hydrogen atom, amino group, carboxyl group or hydrocarbon group.

2. The light-emitting device according to claim 1, characterized in that, The electron transport layer includes: A first electron transport sublayer is disposed between the light-emitting layer and the cathode; and A second electron transport sublayer is disposed between the first electron transport sublayer and the cathode; The rough structure is disposed on the side of the second electron transport sublayer near the cathode; the material of the first electron transport sublayer includes the compound; the material of the second electron transport sublayer includes the compound, or the material of the second electron transport sublayer includes nano-ZnO.

3. The light-emitting device according to claim 2, characterized in that, The light-emitting device has an upright structure and is provided with a light-emitting area and a non-light-emitting area. The stacked structure of the light-emitting area includes the anode, the light-emitting layer, the electron transport layer and the cathode; the stacked structure of the non-light-emitting area includes the light-emitting layer, the electron transport layer and the cathode, and the stacked structure of the non-light-emitting area does not include the anode. The rough structure is disposed in the light-emitting region, and the materials of the first electron transport sublayer and the second electron transport sublayer independently include the compound.

4. The light-emitting device according to claim 2 or 3, characterized in that, The thickness ratio of the first electron transport sublayer to the second electron transport sublayer is 1:(0.5~1).

5. The light-emitting device according to claim 1, characterized in that, The method for preparing the compound includes the following steps: A mixture of the first compound and the second compound is provided; The mixture was heat-treated in an inert gas atmosphere to obtain the compound; The first compound has the structure shown in general formula (II): (Ⅱ) In general formula (II), R is selected from hydrogen atom, amino group, carboxyl group or hydrocarbon group; The second compound is selected from nano ZnO.

6. The light-emitting device according to claim 5, characterized in that, In the mixture, the mass ratio of the first compound to the second compound is 1:(3-5).

7. The light-emitting device according to claim 1, characterized in that, The material of the light-emitting layer is selected from organic light-emitting materials or quantum dots; The organic light-emitting material is selected from at least one of diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent materials, TTPA fluorescent materials, TBRb fluorescent materials or DBP fluorescent materials; The quantum dots are selected from at least one of single-component quantum dots, core-shell structured quantum dots, inorganic perovskite quantum dots, or organic-inorganic hybrid perovskite quantum dots; when the quantum dots are selected from single-component quantum dots or core-shell structured quantum dots, the component of the quantum dots is selected from group II-VI compounds, group III-V compounds, group IV-VI compounds, or group I compounds. III At least one of group II-VI compounds, wherein the group II-VI compounds are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgT At least one of e, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, or HgZnSTe, wherein the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, G At least one of aNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, or InAlPSb, wherein the IV-VI compound is selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, or SnPbSTe, wherein the I III The group VI compound is selected from at least one of CuInS2, CuInSe2 or AgInS2.

8. The light-emitting device according to claim 1, characterized in that, The light-emitting device further includes a hole transport layer disposed between the anode and the light-emitting layer. The material of the hole transport layer is selected from NiO, WO3, MoO3, CuO, poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine), 3-hexyl-substituted polythiophene, poly(9-vinylcarbazole), poly[bis(4-phenyl)(4-butylphenyl)amine], poly(N,N'-bis(4-butylphenyl)... At least one of N,N'-diphenyl-1,4-phenylenediamine-CO-9,9-dioctylfluorene, 4,4',4''-tris(carbazole-9-yl)triphenylamine, 4,4'-di(9-carbazole)biphenyl, N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine or N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine.

9. A method for fabricating a light-emitting device, characterized in that, The light-emitting device has an upright structure, and the fabrication method includes the following steps: An anode is provided, and a light-emitting layer is formed on one side of the anode; An electron transport material layer is formed on the side of the light-emitting layer away from the anode, and the material of the electron transport material layer includes compounds; The electron transport material layer is treated with the first illumination condition to obtain the electron transport precursor layer; A cathode is formed on the side of the electron transport precursor layer away from the light-emitting layer; The stacked structure containing the electron transport precursor layer and the cathode is processed under a second illumination condition to obtain a stacked structure containing the electron transport layer and the cathode. The electron transport layer has a rough structure on the side near the cathode, and the compound has the structure shown in the general formula (Ⅰ): (Ⅰ) Wherein, X is selected from nano ZnO, and the metal atoms of the nano ZnO are coordinated with double-bonded oxygen, and the particle size of the nano ZnO is 2 nm to 15 nm. R is selected from hydrogen atom, amino group, carboxyl group or hydrocarbon group.

10. The preparation method according to claim 9, characterized in that, The preparation method includes the following steps: An anode is provided, and a light-emitting layer is formed on one side of the anode; A first electron transport material layer is formed on the side of the light-emitting layer away from the anode, and the material of the first electron transport material layer includes the compound; The first electron transport material layer is processed under the first illumination condition to obtain the first electron transport precursor layer; A second electron transport material layer is formed on the side of the first electron transport precursor layer away from the light-emitting layer, and the material of the second electron transport material layer includes the compound; The second electron transport material layer has a light-emitting region and a non-light-emitting region. The light-emitting region is treated with a second illumination condition to obtain a second electron transport precursor sublayer. The rough structure is formed on the side of the second electron transport precursor sublayer away from the first electron transport precursor sublayer, and the rough structure is located in the light-emitting region; A cathode is formed on the side of the second electron transport precursor layer away from the first electron transport precursor layer; The first electron transport precursor sublayer and the second electron transport precursor sublayer are processed under a second illumination condition to obtain an electron transport layer containing the first electron transport sublayer and the second electron transport sublayer.

11. A method for fabricating a light-emitting device, characterized in that, The light-emitting device has an inverted structure, and the fabrication method includes the following steps: A cathode is provided, and an electron transport material layer is formed on one side of the cathode, the material of the electron transport material layer including compounds; The electron transport material layer is treated with the first illumination condition to obtain the electron transport precursor layer; A light-emitting layer is formed on the side of the electron transport precursor layer away from the cathode; An anode is formed on the side of the light-emitting layer away from the electron transport precursor layer; The stacked structure containing the electron transport precursor layer and the light-emitting layer is processed under a second illumination condition to obtain a stacked structure containing the electron transport layer and the light-emitting layer. The electron transport layer has a rough structure on the side near the cathode, and the compound has the structure shown in the general formula (Ⅰ): (Ⅰ) Wherein, X is selected from nano ZnO, and the metal atoms of the nano ZnO are coordinated with double-bonded oxygen, and the particle size of the nano ZnO is 2 nm to 15 nm. R is selected from hydrogen atom, amino group, carboxyl group or hydrocarbon group.

12. The preparation method according to any one of claims 9 to 11, characterized in that, The light source for the first illumination condition is ultraviolet light emitting wavelengths of 363nm to 367nm, and the light source for the second illumination condition is ultraviolet light emitting wavelengths of 252nm to 256nm.

13. A display device, characterized in that, The display device includes a light-emitting device as described in any one of claims 1 to 8, or a light-emitting device prepared by the preparation method as described in any one of claims 9 to 12.

Images