Electroluminescent device encapsulation desiccant solid film, dry liquid agent and encapsulation method thereof

Abstract

The present application relates to the technical field of display, and discloses an electroluminescent device packaging desiccant solid film, a drying liquid agent and a packaging method thereof, the electroluminescent device packaging desiccant solid film comprises ZnO nanoparticles doped with metal atoms, and the surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structure; the drying liquid agent for the electroluminescent device packaging desiccant solid film contains alcohol as a solvent and a desiccant, the desiccant comprises ZnO nanoparticles doped with metal atoms, and the surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structure; the method for packaging the electroluminescent device comprises the steps of dropping the drying liquid agent described above on the inner surface of a packaging cover plate and heating to remove the solvent to form a solid film.The electroluminescent device packaging desiccant solid film, the drying liquid agent and the packaging method thereof provided by the present application are simple and efficient, low in cost, easy to store, good in packaging effect and strong in adsorption capacity.

Description

Technical Field

[0001] This invention belongs to the field of display technology, and particularly relates to a solid film for encapsulating desiccant in electroluminescent devices, a desiccant liquid, and an encapsulation method thereof. Background Technology

[0002] QLED (Quantum Dot Light Emitting Diodes) have a structure very similar to OLED technology. The main difference is that the light-emitting center of a QLED is a thin layer of quantum dots made of quantum dots, which is then placed in the backlight unit (BLU) of a liquid crystal display (LCD). Quantum dot LEDs have attracted widespread attention in the optoelectronic industry due to their excellent performance, particularly in color purity, brightness, and emission tunability. They also achieve excellent performance in efficiency and stability, making them a preferred device for display and lighting technologies.

[0003] The reactive metal used as the metal cathode in a light-emitting device readily reacts with atmospheric water vapor to form metal oxides or hydroxides, affecting charge injection. Furthermore, atmospheric water and oxygen can chemically react with the luminescent and functional materials in the QLED device, causing a decline in color purity, brightness, and efficiency. To maintain the performance and reasonable lifespan of QLED devices, suitable encapsulation barrier materials are used to ensure that the water vapor permeability (WVTR) is <1×10⁻⁶. -3 g / m 2 / day (25℃, 40%RH)), oxygen permeability <1×10 -3 cm 3 / m 2 / day is one of the key factors in the development of QLED display devices.

[0004] Currently, by encapsulating QLED devices to isolate them from oxygen and moisture in the air, and filling the device with desiccant (or attaching desiccant sheets) to absorb moisture, oxygen, and various acid / alkaline gases inside the device, the lifespan of the device can be effectively extended.

[0005] Typically, QLEDs and other light-emitting devices employ a sandwich structure for encapsulation. Metal oxides or inorganic oxides are deposited on a substrate film (such as polyester PET, polyimide PI, polyethylene naphthalate PEN, or polyvinyl alcohol PVA) using methods like vacuum evaporation, ion sputtering, or chemical vapor deposition. Then, an organic film is coated onto this substrate to form a three- or multi-layer encapsulation film. In this three-layer structure, the metal oxide or inorganic oxide film plays a crucial role in blocking water and oxygen permeation. For example, a known method for preparing high-barrier electronic encapsulation films involves atomic layer deposition (ALD) to deposit aluminum oxide / magnesium oxide onto a substrate film as a water and oxygen barrier layer (J. Mater. Chem C, 2017, 5, 4017-4024). However, due to the limited cavity size of ALD, large-area, continuous-scale fabrication is difficult and costly. Chinese invention patent ZL (02149122.4) discloses an encapsulation layer for an organic electroluminescent device, its preparation method, and its application. This encapsulation layer comprises a thin film layer consisting of alternating polymer and ceramic material layers at a certain number of cycles, and a thick film layer of organic insulating material located on top of the thin film layer. This method requires repeated fabrication of the ceramic and polymer layers, making the process relatively cumbersome. Chinese invention patent (ZL200710105977.x) also reports a flexible organic electroluminescent device whose encapsulation structure includes a thick film layer formed of a polymer material. This thick film layer is doped with at least one of an alkali metal, alkaline earth metal, metal oxide, zeolite, metal purification of long-chain alkanes, sulfate, chloride, or perchlorate. Effective adsorption of water and oxygen is achieved by introducing this encapsulation material on both sides of the device. Chinese invention patent (CN 201510132928.X) discloses another waterproof and oxygen barrier layer for waterproof and oxygen-resistant encapsulation of flexible electronic and display devices. It utilizes inorganic particles dispersed on a polymer layer, or inorganic particles generated or grafted onto polymer monomers with carbon-carbon double bonds such as methyl methacrylate, vinyl chloride, or styrene through chemical reaction, or dianhydride and diamine monomers, diacid and diamine monomers, or diacid and diol monomers, and then obtains a polymer layer through polymerization reaction to achieve highly efficient waterproof and oxygen-resistant performance.

[0006] These types of barrier films can achieve up to 10 -5 -10 -6 While water and oxygen barrier properties can be achieved in QLED devices, the manufacturing cost is too high, making it difficult to meet the differentiated and cost-effective needs of these mid-range barrier films. Furthermore, existing desiccants require inert gas protection, necessitating stringent storage conditions.

[0007] Therefore, there is an urgent need to develop a simple, efficient, low-cost, and easily fabricated encapsulation material for large-area and continuous fabrication in order to further improve the efficiency of QLED devices. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a solid film for encapsulating desiccants in electroluminescent devices, a desiccant, and an encapsulation method thereof, which is simple, efficient, low-cost, has good encapsulation effect, and strong adsorption capacity.

[0009] The first objective of this invention is to provide a solid film for encapsulating desiccant in an electroluminescent device, comprising ZnO nanoparticles doped with metal atoms, wherein the surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structures.

[0010] As a preferred embodiment of the above-mentioned solid film for encapsulating desiccant in electroluminescent devices, the organic functional group accounts for 8 to 25% of the mass percentage of the solid film.

[0011] As a preferred embodiment of the solid film for encapsulating the above-mentioned electroluminescent device desiccant, the doped metal atoms include at least one of Mg, Li, Al, Ga, and Sn.

[0012] As a preferred embodiment of the solid film for encapsulating the electroluminescent device, the doping amount of metal atoms is 0.1%-30%.

[0013] As a preferred embodiment of the solid film for encapsulating the electroluminescent device described above, the thickness of the solid film is less than 500 micrometers.

[0014] The second objective of this invention is to provide a desiccant liquid for encapsulating solid films of electroluminescent devices, characterized in that it contains an alcohol solvent and a desiccant, wherein the desiccant comprises ZnO nanoparticles doped with metal atoms, and the surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structures.

[0015] As a preferred embodiment of the above-mentioned desiccant for solid films used in the encapsulation of electroluminescent devices, the alcohol solvent includes short-chain monohydric alcohols or dihydric alcohols with boiling points below 100°C.

[0016] As a preferred embodiment of the above-mentioned desiccant for solid films used in the encapsulation of electroluminescent devices, the organic functional group accounts for 8 to 25% of the mass percentage of the desiccant.

[0017] As a preferred embodiment of the above-mentioned desiccant for solid films used as desiccants for electroluminescent device packaging, the doped metal atoms include at least one of Mg, Li, Al, Ga, and Sn.

[0018] As a preferred embodiment of the above-mentioned desiccant for solid films used as desiccants for electroluminescent device packaging, the doping amount of metal atoms is 0.1%-30%.

[0019] As a preferred embodiment of the above-mentioned desiccant for solid films used in the encapsulation of electroluminescent devices, the ZnO nanoparticles doped with metal atoms account for 10%-30% of the weight percentage of the desiccant.

[0020] A third objective of this invention is to provide a method for encapsulating an electroluminescent device, wherein the aforementioned drying agent is dropped onto the inner surface of the encapsulation cover and the solvent is removed by heating.

[0021] As a preferred embodiment of the above-mentioned method for encapsulating electroluminescent devices, the thickness of the solid film formed after heating is less than 500 micrometers.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The surface of ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structure, which can form hydrogen bonds with H2O to play an adsorption role. Moreover, its loose and porous wurtzite structure has an adsorption effect on small molecules generated during the curing process of epoxy UV adhesives.

[0024] 2. The doped metal atoms help extend the shelf life of the adsorbent. ZnO nanoparticles doped with metal atoms can be stored in the air in solution form as an adsorbent. They are easy to prepare, low in cost, and easy to store.

[0025] 3. Applying the adsorbent to the sealing cover has no effect on other materials;

[0026] 4. Adsorbents can adsorb water / oxygen and other gaseous substances generated during device fabrication, thereby improving device efficiency;

[0027] 5. When using this adsorbent to encapsulate QLED devices, simply drop the adsorbent onto the inner surface of the encapsulation cover, heat to remove the solvent and form a film; the operation is simple.

[0028] 6. The adsorbent is used to form a film that adheres to the inner surface of the encapsulation cover, eliminating the need for additional functional barrier films and reducing the thickness of the device. Attached Figure Description

[0029] Appendix Figure 1 This is a schematic diagram of the structure of the QLED display device provided by the present invention.

[0030] In the picture:

[0031] 100 - Substrate, 200 - QLED device, 300 - Encapsulation cover plate, 400 - Solid film, 500 - Encapsulation adhesive. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be described in detail below. It should be noted that these embodiments are only partial, not complete.

[0033] As used herein, expressions such as "at least one" modify the entire list of elements without modifying any individual elements of the list when placed before or after it. Unless otherwise defined, all terms in this specification (including technical and scientific terms) are to be defined as commonly understood by one of ordinary skill in the art. Terms defined in common dictionaries should be interpreted as consistent with their meaning in the context of the relevant art and in this disclosure, and should not be interpreted ideally or overly broadly unless clearly defined. Furthermore, unless expressly stated to the contrary, the terms "comprising" and "including," when used in this specification, indicate the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or sets thereof. Therefore, the above terms should be understood to mean that the stated elements are included, but not that any other elements are excluded.

[0034] As used herein, the term “and / or” includes any and all combinations of one or more of the related listed items. The term “or” means “and / or”.

[0035] It will be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms.

[0036] As used herein, “about” or “approximately” includes the stated value and means within an acceptable range of deviation from the specific value, as determined by one of ordinary skill in the art taking into account the measurement in question and the errors associated with the measurement of the specific quantity (i.e., limitations of the measurement system). For example, “about” may mean a deviation from the stated value within one or more standard deviations, or within ±10%, ±5%.

[0037] As described in the background section, the existing barrier film manufacturing cost is too high, making it difficult to meet the differentiated and low-cost requirements of mid-range barrier films. In addition, the existing desiccants require the protection of inert gas, and the storage conditions are harsh.

[0038] Based on this, on the one hand, this invention provides a solid film for encapsulating desiccants in electroluminescent devices, comprising ZnO nanoparticles doped with metal atoms. The surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structures, wherein the doping amount of metal atoms is 0.1%-30%. The organic functional groups containing -OH structures coated on the surface of the ZnO nanoparticles can form hydrogen bonds with H2O to achieve adsorption and thus realize the drying function. Preferably, in this invention, the mass percentage of organic functional groups relative to the solid film is 8-25%. This controlled content ensures the distribution density of the ZnO nanoparticles doped with metal atoms in the solid film. Furthermore, the ZnO nanoparticles doped with metal atoms form a loose and porous wurtzite structure, which has an adsorption effect on small molecules.

[0039] Specifically, in this invention, the doped metal atoms include at least one of Mg, Li, Al, Ga, and Sn. The doped metal atoms form spacers in the ZnO structure, which can inhibit the aggregation of the structure, thereby helping to extend the shelf life of the nanoparticles.

[0040] In addition, the thickness of the aforementioned solid film is less than 500 micrometers. This thickness ensures that the size of the packaged device is not too thick, and also ensures that there are sufficient ZnO nanoparticles doped with metal atoms in the solid film to adsorb water and oxygen.

[0041] Furthermore, the ZnO nanoparticles doped with metal atoms of the present invention can be stored in the air in solution form as an adsorbent, without the need for inert gas protection. For example, the desiccant liquid for solid films used in electroluminescent device encapsulation provided by the present invention contains an alcohol solvent and a desiccant, the desiccant comprising ZnO nanoparticles doped with metal atoms, the surface of which has organic functional groups containing -OH structures. Similarly, the doping amount of metal atoms is 0.1%-30%, and the doped metal atoms include at least one of Mg, Li, Al, Ga, and Sn. The surface of ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structures, which can form hydrogen bonds with H2O to achieve adsorption and thus achieve drying function. As an adsorbent, ZnO nanoparticles doped with metal atoms can dissolve in alcohol solvents. At the same time, the doped metal atoms form spacers for the ZnO structure and the -OH ligands form on the surface of the nanoparticles, which can inhibit the aggregation of the structure. They can be stored in the air in solution form. They are easy to prepare, inexpensive, and easy to store. Furthermore, after ZnO nanoparticles are doped with metal atoms, they form a loose and porous wurtzite structure, which has an adsorption effect on small molecules.

[0042] This invention relates to the bonding of -OH organic functional groups to the surface of ZnO nanoparticles doped with metal atoms. These organic functional groups facilitate the dissolution of the ZnO nanoparticles in an alcohol solvent. Preferably, the alcohol solvent comprises short-chain monohydric alcohols or diols with boiling points below 100°C, and the organic functional group constitutes 8–25% of the desiccant by mass. By selecting a low-boiling-point alcohol solvent, the solvent can be evaporated at low temperatures during the subsequent curing of the desiccant into a film. Controlling the content of the organic functional groups ensures the optimal distribution density of the ZnO nanoparticles doped with metal atoms in the solid film during curing, thereby ensuring adsorption properties.

[0043] In a preferred embodiment of the present invention, the ZnO nanoparticles doped with metal atoms account for 10%-30% by weight of the desiccant. This limited content ensures the density of the film formed by the desiccant during subsequent solid film formation, thus ensuring adsorption capacity.

[0044] The specific preparation methods for the desiccant liquid used in the solid film of desiccant for electroluminescent device packaging include:

[0045] S1. Provide a zinc-containing compound and a compound containing doped metal atoms, which are miscible in an alcohol solvent;

[0046] S2, reaction upon addition of an alkaline compound:

[0047] S3. Add 2-5 times the volume of purification agent to dissolve the purified ZnO precipitate doped with metal atoms in an alcohol solvent to obtain an alcohol solution of the ZnO nanoparticles doped with metal atoms.

[0048] The zinc-containing compounds include one of zinc acetate, zinc stearate, zinc chloride, and zinc carbonate; the alkaline compounds include one of tetramethylammonium hydroxide, potassium hydroxide, and sodium hydroxide; the alcohol solvent can be anhydrous ethanol; and the purifying agent can be ethyl acetate. The purpose of adding the purifying agent is to precipitate the target nanoparticles from the original solvent without carrying away residual reactants in the reaction solution, thereby achieving the effect of cleaning the target product.

[0049] The following example demonstrates the preparation of a drying agent using Mg-doped Mg atoms.

[0050] 2g of zinc acetate and 0.8g of magnesium acetate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnMgO precipitate was dissolved in anhydrous ethanol to obtain a ZnMgO ethanol solution, which was used as the adsorbent.

[0051] The following section uses Li-doped liquid as an example to prepare a drying agent.

[0052] 2g of zinc acetate and 0.8g of lithium acetate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnLiO precipitate was dissolved in anhydrous ethanol to obtain a ZnLiO ethanol solution, which was used as the adsorbent.

[0053] The following section uses Sn atom doping as an example to prepare a drying agent.

[0054] 2g of zinc acetate and 0.2g of tin acetate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnSnO precipitate was dissolved in anhydrous ethanol to obtain a ZnSnO ethanol solution, which was used as the adsorbent.

[0055] The following example demonstrates the preparation of a drying agent using Ga-doped gas.

[0056] 2g of zinc acetate and 0.2g of gallium acetylacetonate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnGaO precipitate was dissolved in anhydrous ethanol to obtain a ZnGaO ethanol solution, which was used as the adsorbent.

[0057] The following example demonstrates the preparation of a drying agent using Al-doped liquid.

[0058] 2g of zinc acetate and 0.2g of aluminum acetylacetonate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate was added in three times the volume of the reaction system for purification. The purified ZnAlO precipitate was dissolved in anhydrous ethanol to obtain a ZnAlO ethanol solution, which was used as the adsorbent.

[0059] The following example demonstrates the preparation of a drying agent using doped Mg and Al atoms.

[0060] 2g of zinc acetate, 0.8g of magnesium acetate, and 0.2g of aluminum acetylacetonate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnMgAlO precipitate was dissolved in anhydrous ethanol to obtain a ZnMgAlO ethanol solution, which was used as the adsorbent.

[0061] The following example demonstrates the preparation of a drying agent using doped Mg and Li atoms.

[0062] 2g of zinc acetate, 0.8g of magnesium acetate, and 0.8g of lithium acetate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnMgLiO precipitate was dissolved in anhydrous ethanol to obtain a ZnMgLiO ethanol solution, which was used as the adsorbent.

[0063] The following section uses the doping of Mg and Sn atoms as an example to prepare a drying agent.

[0064] 2g of zinc acetate, 0.8g of magnesium acetate, and 0.2g of tin acetate were mixed and dissolved in 30ml of anhydrous ethanol. 2g of tetramethylammonium hydroxide was added, and the mixture was reacted at 25℃ for 1h. Ethyl acetate, three times the volume of the reaction system, was added to purify the mixture. The purified ZnMgSnO precipitate was dissolved in anhydrous ethanol to obtain a ZnMgSnO ethanol solution, which was used as the adsorbent.

[0065] It is evident that the novel application of ZnO nanoparticles doped with metal atoms as an adsorbent can be dissolved in alcohol solvents and stored in solution form, making it convenient to preserve.

[0066] The method for encapsulating electroluminescent devices using the aforementioned desiccant involves dropping the desiccant onto the inner surface of the encapsulation cover and then heating to remove the solvent. The thickness of the solid film formed after heating is less than 500 micrometers. Because the ZnO nanoparticles doped with metal atoms have -OH organic functional groups attached to their surface, these functional groups can promote the formation of a film of the desiccant on the encapsulation cover during the evaporation of the alcohol solvent.

[0067] On the other hand, such as Figure 1 As shown, this embodiment of the invention provides a QLED display device, including a substrate 100, a QLED device 200, and an encapsulation cover plate 300. The QLED device 200 is disposed on the substrate 100, and the encapsulation cover plate 300 is disposed on the substrate 100 and encapsulates the QLED device 200. The inner surface of the encapsulation cover plate 300 is coated with the aforementioned solid film 400, and the periphery of the inner surface of the encapsulation cover plate 300 is bonded to the substrate 100 by an encapsulating adhesive 500. Specifically, the aforementioned adsorbent is dropped into a groove on the inner surface of the encapsulation cover plate 300 (the groove serves to leave a gap between the QLED device and the light-emitting area; the solid film 400 can also be attached even without a groove on the inner surface of the encapsulation cover plate 300), and the ethanol solvent is removed by heating, forming a solid film 400 of the adsorbent in the groove. It is evident that when using this adsorbent to encapsulate QLED devices, it is only necessary to drop the adsorbent into the groove on the inner surface of the encapsulation cover, and then heat it to remove the solvent and form a film. The operation is simple. The film formed by this adsorbent adheres to the inner surface of the encapsulation cover, eliminating the need to stack other functional barrier films, which helps to reduce the thickness of the device.

[0068] This invention also provides a method for manufacturing a QLED display device, comprising the following steps:

[0069] S1. Provide a substrate;

[0070] S2. Form QLED devices on the substrate;

[0071] S3. Provide a sealing cover and the above-mentioned adsorbent liquid;

[0072] S4. The adsorbent is dropped onto the inner surface of the encapsulation cover, and the solvent is removed by heating, forming a solid film of the adsorbent on the inner surface of the encapsulation cover.

[0073] S5. Apply encapsulating adhesive to the periphery of the inner surface of the encapsulation cover and attach the encapsulation cover to the substrate, and cure the encapsulating adhesive;

[0074] Preferably, the thickness of the solid film is less than 500 micrometers, and the encapsulating adhesive is a UV-curable adhesive;

[0075] Preferably, in step S4, the QLED device encapsulation adsorbent is dropped into the groove on the inner surface of the encapsulation cover plate, and the solvent is removed by heating, forming a solid film of the adsorbent liquid in the groove.

[0076] Specifically, step S2 includes:

[0077] S21. Spin-coat PEDOT:pss solution onto the substrate and dry it;

[0078] S22. Spin-coat TFB solution and dry.

[0079] S23. Spin-coat QD n-octane solution and dry;

[0080] S24. Spin-coat ZnMgO ethanol solution and dry;

[0081] S25, vapor-deposited Al electrode.

[0082] During the curing process of the encapsulating adhesive, especially epoxy UV adhesive, small molecules are generated. Since ZnO nanoparticles form a loose and porous wurtzite structure after being doped with metal atoms, this structure has an adsorption effect on small molecules, thus avoiding the influence of small molecules on the device. Furthermore, using this adsorbent liquid for encapsulation can adsorb gaseous substances generated during device fabrication, further improving device efficiency.

[0083] The following example demonstrates the preparation of a QLED display device using ZnMgO ethanol solution as the adsorbent.

[0084] Step 1. Spin-coat PEDOT:pss solution onto ITO substrate and bake at 130℃ for 20 minutes;

[0085] Step 2. Spin-coat the second layer of material: TFB solution, and bake at 130℃ for 20 minutes;

[0086] Step 3. Spin-coat the third layer of material: QD n-octane solution, and bake at 100℃ for 5 minutes;

[0087] Step 4. Spin-coat the fourth layer material: ZnMgO ethanol solution (concentration 20mg / ml), bake at 80℃ for 10min (this step forms the electron transport layer);

[0088] Step 5. Evaporate the fifth layer of material: Al electrode, evaporating 100nm under vacuum conditions;

[0089] Step 6. Add ZnMgO ethanol solution (>80mg / ml) dropwise into the groove on the inner surface of the sealing cover (~5mg), and heat at 80℃ for 10min;

[0090] Step 7. Apply UV-curable adhesive around the inner surface of the above-mentioned encapsulation cover and attach the inner surface of this encapsulation cover to the Al electrode surface in Step 5. Irradiate with UV until the encapsulation adhesive is completely cured.

[0091] The following describes the preparation of a QLED display device using a conventional drying sheet (whose main component is calcium dioxide, and which needs to be stored in an inert gas environment for a long time) as a comparative example.

[0092] Step 1. Spin-coat PEDOT:pss solution onto ITO substrate and bake at 130℃ for 20 minutes;

[0093] Step 2. Spin-coat the second layer of material: TFB solution, and bake at 130℃ for 20 minutes;

[0094] Step 3. Spin-coat the third layer of material: QD n-octane solution, and bake at 100℃ for 5 minutes;

[0095] Step 4. Spin-coat the fourth layer material: ZnMgO ethanol solution (concentration 20mg / ml), bake at 80℃ for 10min (this step forms the electron transport layer);

[0096] Step 5. Evaporate the fifth layer of material: Al electrode, evaporating 100nm under vacuum conditions;

[0097] Step 6. Attach the adhesive residue on the back of the drying sheet to the center of the groove on the inner surface of the encapsulation cover.

[0098] Step 7. Apply UV-curable adhesive around the inner surface of the above-mentioned encapsulation cover and attach the inner surface of this encapsulation cover to the Al electrode surface in Step 5. Irradiate with UV until the encapsulation adhesive is completely cured.

[0099] The film surface luminous performance of QLED display devices prepared without a drying sheet during the encapsulation process, using a conventional drying sheet, and using the drying liquid of the present invention were tested and compared as follows:

[0100]

[0101]

[0102] It is evident that the light emission of a QLED display device without a drying sheet during the encapsulation process is very uneven across the film surface; the light emission uniformity of a QLED display device encapsulated using a traditional drying sheet is improved, but still not uniform enough; the QLED display device encapsulated using the drying liquid of this invention has consistent brightness and uniform light emission across the film surface, ensuring the stable performance and lifespan of the QLED display device.

[0103] QLED display devices prepared using the desiccant of this invention but without a desiccant during the packaging process, using a conventional desiccant, and using the desiccant of this invention were subjected to EQE tests after being left for a period of time, and the results are compared as follows:

[0104]

[0105] It is evident that using ZnO nanoparticles doped with metal atoms as a desiccant to encapsulate QLED devices significantly improves device efficiency.

[0106] Although the inventors have described and enumerated the technical solutions of the present invention in detail, it should be understood that for those skilled in the art, it is obvious that modifications and / or alterations to the above embodiments or the adoption of equivalent alternatives can be made without departing from the spirit of the present invention. The terminology appearing in the present invention is used to describe and understand the technical solutions of the present invention and does not constitute a limitation of the present invention.

Claims

1. A solid film for encapsulating desiccant in an electroluminescent device, characterized in that, The invention includes ZnO nanoparticles doped with metal atoms, wherein the surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structures; the doped metal atoms include at least one of Mg, Li, Al, Ga, and Sn, and the organic functional groups account for 8 to 25% of the mass percentage of the solid film.

2. The solid film for encapsulating desiccant in electroluminescent devices according to claim 1, characterized in that, The doping amount of metal atoms is 0.1%-30%.

3. The solid film for encapsulating desiccant in electroluminescent devices according to any one of claims 1-2, characterized in that, The thickness of the solid film is less than 500 micrometers.

4. A desiccant for use in encapsulating solid films of desiccants for electroluminescent devices, characterized in that, It contains an alcohol solvent and a desiccant, wherein the desiccant includes ZnO nanoparticles doped with metal atoms, and the surface of the ZnO nanoparticles doped with metal atoms has organic functional groups containing -OH structures; The doped metal atoms include at least one of Mg, Li, Al, Ga, and Sn, and the organic functional group accounts for 8 to 25% of the mass percentage of the desiccant.

5. The desiccant for solid films used in the encapsulation of electroluminescent devices according to claim 4, characterized in that, The alcohol solvents include short-chain monohydric alcohols or dihydric alcohols with boiling points below 100°C.

6. The desiccant for solid films used in the encapsulation of electroluminescent devices according to claim 4, characterized in that, The doping amount of metal atoms is 0.1%-30%.

7. The desiccant for solid films used in the encapsulation of electroluminescent devices according to claim 4, characterized in that, The ZnO nanoparticles doped with metal atoms account for 10%-30% of the weight percentage of the drying agent.

8. A method for packaging an electroluminescent device, characterized in that, The drying agent according to any one of claims 4-7 is dropped onto the inner surface of the encapsulation cover, and the solvent is removed by heating.

9. The method for packaging an electroluminescent device according to claim 8, characterized in that, The thickness of the solid film formed after heating is less than 500 micrometers.

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