Packaging adhesive material and display panel

Abstract

The embodiment of the invention discloses a packaging adhesive material and a display panel, a non-acrylic photo-curing oligomer is used as a main body material of the packaging adhesive material, and when the packaging adhesive material is used for packaging a device of a QLED display panel, the packaging adhesive material is cured through ultraviolet radiation, so that the packaging effect of the packaging adhesive material is improved. The non-acrylic photocuring oligomer provided by the invention does not release a large amount of acrylic acid, so that the device morphology of the QLED display panel is not degraded; and the carboxylic acid monomer is added into the packaging adhesive material, and the content of the carboxylic acid monomer is strictly controlled, so that in the ultraviolet curing process, a small amount of carboxylic acid monomer is volatilized to the QD surface of a device, the effect of passivating QD surface defects can be achieved, and the efficiency of the device is improved. Therefore, when the packaging adhesive material provided by the embodiment of the invention is used for packaging the device, the appearance of the device cannot be degraded on the basis of improving the efficiency of the device, so that the service life of the display panel is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and in particular to a packaging adhesive material and a display panel. Background Art

[0002] As a new type of luminescent material, quantum dots (QD) have the advantages of high light color purity, high light quantum efficiency, adjustable light color, and long service life. They have become a research hotspot for luminescent materials in new light-emitting diodes. Therefore, quantum dot light emitting diodes (QLEDs) with quantum dot materials as the light-emitting layer have become the main research direction of new display devices.

[0003] During the development of QLED devices, in order to protect the devices and prevent them from being corroded by water and oxygen in the air, QLED devices are usually packaged. The packaging methods are generally divided into glass packaging and thin film packaging. Glass packaging is to bond the cover plate and the substrate in an inert gas environment with a packaging glue, and cure the packaging glue by ultraviolet irradiation to achieve the purpose of protecting the device. Thin film packaging is to deposit inorganic packaging layer / organic ultraviolet curing glue / inorganic packaging layer in sequence on the top of the device through chemical vapor deposition (CVD) and inkjet printing (IJP), and finally a layer of Lami film is affixed to prevent scratches.

[0004] Whether it is glass packaging or thin film packaging, encapsulation adhesive material is required. Encapsulation adhesive material is a material that can undergo rapid physical and chemical changes in a short period of time after being exposed to light, and then cross-link and cure. It usually has reactive groups that can be photocured, such as unsaturated double bonds or epoxy groups.

[0005] However, the packaging glue materials commonly used in the related art cannot simultaneously improve device efficiency and device life. Summary of the invention

[0006] The embodiments of the present invention provide a packaging adhesive material and a display panel. When the packaging adhesive material is used to form a packaging adhesive layer of a display panel, the efficiency of the device can be improved without affecting the morphology of the device.

[0007] An embodiment of the present invention provides a packaging adhesive material, which includes a non-acrylic light-curable oligomer, a carboxylic acid monomer, a photoinitiator and a reactive diluent.

[0008] Optionally, in the above-mentioned encapsulation adhesive material provided in an embodiment of the present invention, the mass fraction of the non-acrylic photocurable oligomer is 50% to 80%, the mass fraction of the carboxylic acid monomer is 0.1% to 5%, the mass fraction of the photoinitiator is less than 5%, and the mass fraction of the reactive diluent is 10% to 50%.

[0009] Optionally, in the above-mentioned packaging adhesive material provided by the embodiment of the present invention, the carboxylic acid monomer includes at least one of acrylic acid monomer, isobutyric acid, methacrylic acid, and a carboxylic acid monomer with a carbon chain length of 8 to 18 carbon atoms.

[0010] Optionally, in the above-mentioned packaging adhesive material provided by the embodiment of the present invention, the non-acrylic light-curable oligomer includes at least one of unsaturated polyester, polyurethane, epoxy resin, and silicone oligomer.

[0011] Optionally, in the above-mentioned packaging adhesive material provided by an embodiment of the present invention, the unsaturated polyester has the following structural formula:

[0012]

[0013] Wherein, R1 is a chain hydrocarbon or an aromatic hydrocarbon.

[0014] Optionally, in the above-mentioned packaging adhesive material provided by an embodiment of the present invention, the polyurethane has the following structural formula:

[0015]

[0016]

[0017] Among them, R2 is a chain hydrocarbon group, an aromatic group or a cyclic hydrocarbon group, R3 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, R4 is a connecting group including 2 to 6 carbon atoms, and R5 is a vinyl group or an epoxy group.

[0018] Optionally, in the above-mentioned packaging adhesive material provided by the embodiment of the present invention, the epoxy resin includes glycidyl epoxy resin, aliphatic epoxy resin or phenolic epoxy resin.

[0019] Optionally, in the above-mentioned encapsulation adhesive material provided in an embodiment of the present invention, the organosilicon oligomer has the following structural formula:

[0020]

[0021] Wherein, R6 is a chain hydrocarbon group or a chain hydrocarbon oxy group, R7 is a connecting group including 2 to 6 carbon atoms, and R8 is a vinyl group or an epoxy group.

[0022] Optionally, in the above-mentioned packaging adhesive material provided by an embodiment of the present invention, the photoinitiator includes at least one of a free radical photoinitiator and a cationic photoinitiator.

[0023] Optionally, in the above-mentioned packaging glue material provided by an embodiment of the present invention, the free radical photoinitiator includes benzophenone and its derivatives, thioxanthone, anthraquinone, benzoin and its derivatives, benzyl derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-aminoalkyl phenone, and acylphosphine oxide; the cationic photoinitiator includes diaryl iodonium salts, triaryl sulfonium salts, and aryl ferrocenium salts.

[0024] Optionally, in the above-mentioned packaging adhesive material provided by an embodiment of the present invention, the reactive diluent molecule contains at least one carbon-carbon double bond and / or one epoxy group.

[0025] Optionally, in the above-mentioned encapsulation glue material provided in an embodiment of the present invention, the active diluent includes at least one of acrylates, methacrylates, vinyls, n-alcohol diacrylates, n-alcohol triacrylates, n-alcohol tetraacrylates, ..., n-alcohol m-acrylates, etc., wherein n=2~4, m=2~8.

[0026] Optionally, in the above-mentioned encapsulation adhesive material provided in the embodiment of the present invention, the acrylates include n-butyl acrylate, isooctyl acrylate, isodecyl acrylate, lauryl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate, isobornyl acrylate, tetrahydrofuran methyl acrylate or phenoxyethyl acrylate;

[0027] The methacrylates include hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, isobornyl methacrylate or tetrahydrofuran methyl methacrylate;

[0028] The vinyls include styrene, vinyl acetate, N-vinyl pyrrolidone or long-chain olefins.

[0029] Correspondingly, an embodiment of the present invention further provides a display panel, comprising a display substrate and a cover plate arranged opposite to each other, wherein a packaging adhesive layer formed by the packaging adhesive material provided in the embodiment of the present invention is arranged between the display substrate and the cover plate.

[0030] Optionally, in the above-mentioned display panel provided by an embodiment of the present invention, the display substrate includes a base substrate and a first electrode, a pixel defining layer, a quantum dot light-emitting functional layer and a second electrode arranged on a side of the base substrate facing the cover plate; wherein,

[0031] The packaging adhesive layer is bonded to the peripheral areas of the display substrate and the cover plate;

[0032] Alternatively, the encapsulation layer covers the display substrate, and the display panel further comprises: a first inorganic encapsulation layer disposed between the display substrate and the encapsulation layer, and a second inorganic encapsulation layer disposed between the encapsulation layer and the cover plate.

[0033] The beneficial effects of the present invention are as follows:

[0034] An encapsulation adhesive material and a display panel provided by an embodiment of the present invention adopt a non-acrylic photocurable oligomer as the main material of the encapsulation adhesive material. When the encapsulation adhesive material is used to encapsulate the device of the QLED display panel, when the encapsulation adhesive material is cured by ultraviolet irradiation, the non-acrylic photocurable oligomer provided by the present invention will not release a large amount of acrylic acid, and thus will not deteriorate the device morphology of the QLED display panel; and because the encapsulation adhesive material of the present invention adds carboxylic acid monomers, by strictly controlling the content of the carboxylic acid monomers, during the ultraviolet curing process, the small amount of carboxylic acid monomers volatilize to the QD surface in the device, which can passivate the surface defects of the QD, thereby improving the efficiency of the device. Therefore, when the encapsulation adhesive material provided by the embodiment of the present invention is used to encapsulate the device, it can be achieved that the device morphology will not be degraded on the basis of improving the efficiency of the device, thereby improving the life of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The reaction formula is a reaction of preparing unsaturated polyester by polycondensation reaction of unsaturated dibasic acid or anhydride with diol;

[0036] Figure 2 A schematic diagram of the structure of a display panel provided by an embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the structure of another display panel provided by an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the device structure is a positive structure;

[0039] Figure 5 A schematic diagram of a device structure of an inverted structure;

[0040] Fig. 6A This is the morphology of the quantum dot light-emitting device corresponding to Comparative Example 1;

[0041] Figure 6B is the efficiency of the quantum dot light-emitting device corresponding to Comparative Example 1;

[0042] Fig. 7A This is the morphology of the quantum dot light-emitting device corresponding to Comparative Example 2;

[0043] Figure 7Bis the efficiency of the quantum dot light-emitting device corresponding to Comparative Example 2;

[0044] Figure 8 The morphology of the quantum dot light-emitting device corresponding to Comparative Example 3;

[0045] Fig. 9A The morphology of the quantum dot light-emitting device corresponding to Example 1;

[0046] Fig. 9B is the efficiency of the quantum dot light-emitting device corresponding to Example 1. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. And in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0048] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "include" or "comprise" and the like used in the present invention mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Inside", "outside", "upper", "lower", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0049] It should be noted that the sizes and shapes of the figures in the accompanying drawings do not reflect the actual proportions, but are only intended to illustrate the content of the present invention. The same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0050] At present, several common packaging glue materials include epoxy resin, acrylic resin or their mixtures. When packaging a device, if acrylic resin packaging glue is used, since it contains a small amount of acrylic acid, it will accelerate the forward aging process of the device and improve the efficiency of the device; if epoxy resin packaging glue is used, which does not contain acrylic acid, the efficiency of the device will be lower.

[0051] In order to improve the efficiency of the device, acrylic resin encapsulation glue is usually used in the related technology. However, the inventors of this case have found through experiments that the use of acrylic resin encapsulation glue will lead to the degradation of the device morphology. For example, the device often has black spots or large areas of no light, which is not conducive to the life of the device. After analyzing the reasons for the degradation of the morphology of QLED devices, it was found that the acrylic acid present in the acrylic resin encapsulation glue caused the degradation of the morphology of the QLED device. Among them, the carboxyl group is the coordination group of QD. Part of the acrylic acid remaining in the encapsulation glue material will be released into the QLED device, coordinate with the carboxyl group on the surface of QD, and passivate the QD surface, which is beneficial to the efficiency of the device; however, the acrylic resin encapsulation glue contains a large number of acrylic acid or methacrylic acid units, and a large number of carboxyl groups may be generated during the encapsulation process. The carboxyl group is highly active, so it may also react with the electron transport layer (such as ZnO) or metal electrode in the QLED device, and may generate water and other substances to damage the morphology of the QLED device, which is extremely easy to cause adverse effects. This adverse effect exceeds the effect brought by the improvement of device efficiency.

[0052] Therefore, adopting a packaging adhesive material that can improve device efficiency without affecting device morphology is an issue that technical personnel in this field urgently need to solve.

[0053] In view of this, an embodiment of the present invention provides a packaging adhesive material, including a non-acrylic light-curable oligomer, a carboxylic acid monomer, a photoinitiator, and a reactive diluent.

[0054] The above-mentioned encapsulation adhesive material provided by the embodiment of the present invention adopts a non-acrylic photocurable oligomer as the main material of the encapsulation adhesive material. When the encapsulation adhesive material is used to encapsulate the device of the QLED display panel, when the encapsulation adhesive material is cured by ultraviolet irradiation, the non-acrylic photocurable oligomer provided by the present invention will not release a large amount of acrylic acid, so the device morphology of the QLED display panel will not be degraded; and because the encapsulation adhesive material of the present invention adds carboxylic acid monomers, by strictly controlling the content of carboxylic acid monomers, during the ultraviolet curing process, the small amount of carboxylic acid monomers volatilize to the QD surface in the device, which can passivate the surface defects of the QD, thereby improving the efficiency of the device. Therefore, when the encapsulation adhesive material provided by the embodiment of the present invention is used to encapsulate the device, it can be achieved that the device morphology will not be degraded on the basis of improving the efficiency of the device, thereby improving the life of the display panel.

[0055] In the specific implementation, in the above-mentioned encapsulation adhesive material provided in the embodiment of the present invention, the mass fraction of the non-acrylic photocurable oligomer can be 50% to 80%, the mass fraction of the carboxylic acid monomer can be 0.1% to 5%, the mass fraction of the photoinitiator can be less than 5%, and the mass fraction of the reactive diluent can be 10% to 50%. Since the mass fraction of the carboxylic acid monomer is very small and the carboxylic acid monomer component is fixed, the content of the released carboxylic acid monomer will not exceed the standard during the ultraviolet curing process, and the carboxylic acid monomer will combine with the defects on the surface of the QD, that is, the carboxyl passivation defect, thereby improving the efficiency of the device; and, after a small amount of carboxylic acid monomer passivates the QD, no more carboxylic acid monomer will react with the electron transport layer and metal electrodes in the device, thereby not corroding the device and not destroying the device structure.

[0056] In the specific implementation, in the above-mentioned encapsulation glue material provided in the embodiment of the present invention, the carboxylic acid monomer may include but is not limited to at least one of acrylic acid monomer, isobutyric acid, and methacrylic acid. Specifically, acrylic acid monomer, isobutyric acid, and methacrylic acid are all acid substances with shorter carbon chains; of course, the carboxylic acid monomer in the embodiment of the present invention may also be an acid substance with longer carbon chains, for example, the carbon chain length of the carboxylic acid monomer may be 8 to 18 carbon atoms, and the acidity of the long-chain carboxylic acid monomer is very weak, so the activity of reacting with the electron transport layer and the metal is very low, which can further reduce the damage to the QLED device. Optionally, the content of the long-chain carboxylic acid monomer may be more than that of the short-chain acrylic acid. At the same time, the viscosity of the long-chain carboxylic acid is relatively large, and compared with the short-chain acrylic acid, the viscosity of the encapsulation glue system can also be appropriately increased, and the glue will not overflow, which is convenient for the encapsulation process. For example, the long-chain carboxylic acid monomer in the present invention can be oleic acid containing 18 carbon chains, and of course it can also be other carboxylic acid monomers with a carbon chain length of 8 to 18 carbon atoms, and the present invention is not limited to this.

[0057] Optionally, the carboxylic acid monomer in the embodiment of the present invention can also be used in combination with a long-chain carboxylic acid and a short-chain carboxylic acid. Therefore, the carboxylic acid monomer in the present invention can include but is not limited to at least one of acrylic acid monomer, isobutyric acid, methacrylic acid, and a carboxylic acid monomer with a carbon chain length of 8 to 18 carbon atoms.

[0058] In specific implementation, in the above-mentioned encapsulation adhesive material provided in the embodiment of the present invention, the non-acrylic light-curable oligomer may include but is not limited to at least one of unsaturated polyester, polyurethane, epoxy resin, and silicone oligomer. When the present invention uses the above-mentioned unsaturated polyester, polyurethane, epoxy resin or silicone oligomer as a monomer for polymerization, these monomers do not contain acrylic acid. When these monomers are combined with a reactive diluent to form a polymer film, that is, when the device of the display panel is encapsulated, a large amount of acrylic acid will not be released, so the device morphology will not be degraded.

[0059] In a specific implementation, in the above-mentioned packaging adhesive material provided in the embodiment of the present invention, the unsaturated polyester has the following structural formula:

[0060]

[0061] Wherein, R1 can be a chain hydrocarbon or an aromatic hydrocarbon.

[0062] Specifically, A linear or branched polyester molecule containing a carbon-carbon double bond (C=C) that can undergo polymerization reaction. It is mainly prepared by polycondensation of unsaturated dibasic acid or anhydride with diol. The reaction path is as follows Figure 1 As shown. Among them, the unsaturated dibasic acid or anhydride mainly includes maleic acid or anhydride, fumaric acid or anhydride, and the diol mainly includes ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,4-butanediol, etc. When the unsaturated dibasic acid or anhydride and the diol undergo condensation reaction, a part of acid or anhydride will also be added to the reactants, such as phthalic acid or anhydride, succinic acid or anhydride, adipic anhydride and other saturated dibasic acids or anhydrides, etc., which are used to improve the elasticity of unsaturated polyester, reduce volume shrinkage, and increase the plasticity of polyester.

[0063] In a specific implementation, in the above-mentioned packaging adhesive material provided in the embodiment of the present invention, the polyurethane has the following structural formula:

[0064]

[0065] Among them, R2 can be a chain hydrocarbon group, an aromatic group or a cyclic hydrocarbon group, R3 can be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, R4 can be a connecting group including 2 to 6 carbon atoms, and R5 can be a vinyl group or an epoxy group.

[0066] Specifically, the above polyurethane is prepared by reacting the isocyanate (-N=C=O) in isocyanate with the hydroxyl in the long-chain diol to form an urethane bond. The above two polyurethanes contain a photocurable group (R5). According to the difference of the photocurable group (R5), they can generally be divided into polyurethane epoxy resin and polyurethane vinyl resin. For example, the specific structure of polyurethane epoxy resin can be:

[0067]

[0068] The molecular chain contains an urethane bond (-OOC-NH-) and a photocurable group (epoxy group, -CH2CH2O-), which forms a polymer film by combining with an active diluent.

[0069] In the specific implementation, in the above-mentioned encapsulation adhesive material provided in the embodiment of the present invention, the epoxy resin may include but is not limited to glycidyl epoxy resin, aliphatic epoxy resin or phenolic epoxy resin. Specifically, the oligomers of glycidyl epoxy resin, aliphatic epoxy resin or phenolic epoxy resin all contain epoxy groups (photocuring groups), such as ethylene oxide, propylene oxide, epoxy cyclopentyl, epoxy cyclohexyl, etc. For example, taking the epoxy resin as phenolic epoxy resin as an example, the structural formula of phenolic epoxy resin is

[0070]

[0071] In a specific implementation, in the above-mentioned encapsulation adhesive material provided in the embodiment of the present invention, the organosilicon oligomer has the following structural formula:

[0072]

[0073] Among them, R6 can be a chain hydrocarbon group or a chain hydrocarbon oxy group, R7 can be a connecting group including 2 to 6 carbon atoms, and R8 can be a vinyl group or an epoxy group.

[0074] Specifically, the above-mentioned organosilicon oligomer is a polymer with a main chain structure of repeated Si-O bonds in polysiloxane, and has a reactive group such as a vinyl group or an epoxy group that can be polymerized and cross-linked.

[0075] In a specific implementation, the non-acrylic light-curable oligomer can be one of the above-mentioned light-curable oligomers, or a mixture of the above-mentioned light-curable oligomers. For example, the non-acrylic light-curable oligomer can be

[0076]

[0077] The mixture of these two will react after mixing, and the reaction path is Where R is

[0078]

[0079] After removing the OCN at both ends, R' is The structure after removing OH, the reaction product Still a non-acrylic photocurable oligomer.

[0080] In a specific implementation, in the above-mentioned encapsulation adhesive material provided in the embodiment of the present invention, the photoinitiator may include at least one of a free radical photoinitiator and a cationic photoinitiator. Optionally, the free radical photoinitiator may include but is not limited to benzophenone and its derivatives, thioxanthone, anthraquinone, benzoin and its derivatives, benzyl derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-aminoalkyl phenone, acylphosphine oxide, and the cationic photoinitiator may include but is not limited to diaryl iodonium salt, triaryl sulfonium salt, aryl ferrocenium salt.

[0081] In a specific implementation, in the encapsulation adhesive material provided in the embodiment of the present invention, the reactive diluent molecule contains at least one carbon-carbon double bond and / or one epoxy group, so that the reactive diluent can undergo a cross-linking reaction with the non-acrylic light-curable oligomer to form a polymer film.

[0082] In specific implementation, in the above-mentioned encapsulation adhesive material provided by the embodiment of the present invention, the active diluent may include but is not limited to at least one of acrylates, methacrylates, vinyls, n-alcohol diacrylates, n-alcohol triacrylates, n-alcohol tetraacrylates, ..., n-alcohol m-acrylates, etc., wherein n=2 to 4, and m=2 to 8. Specifically, since the content of the active diluent is small, it needs to be hydrolyzed to produce acrylic acid, and almost no acrylic acid is produced, so acrylates and methacrylates will not affect the morphology of the device.

[0083] Alternatively, the acrylates include n-butyl acrylate, isooctyl acrylate, isodecyl acrylate, lauryl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate, isobornyl acrylate, tetrahydrofuranyl methyl acrylate or phenoxyethyl acrylate.

[0084] Alternatively, the methacrylates include hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, isobornyl methacrylate or tetrahydrofuranyl methacrylate.

[0085] Alternatively, the vinyls include styrene, vinyl acetate, N-vinyl pyrrolidone or long chain olefins.

[0086] Based on the same inventive concept, an embodiment of the present invention further provides a display panel, such as Figure 2 and Figure 3 As shown, it includes a display substrate 1 and a cover plate 2 which are arranged opposite to each other, and a packaging adhesive layer 3 formed by the packaging adhesive material provided by the embodiment of the present invention is arranged between the display substrate 1 and the cover plate 2.

[0087] The display panel provided by the embodiment of the present invention can improve the device efficiency without deteriorating the device morphology by forming a packaging glue layer using the packaging glue material provided by the embodiment of the present invention, thereby improving the life of the display panel.

[0088] In a specific implementation, in the above display panel provided in the embodiment of the present invention, if Figure 2 and Figure 3 As shown, the display substrate 1 includes a base substrate 11 and a first electrode 12, a pixel defining layer 13, a quantum dot light-emitting functional layer 14 and a second electrode 15 arranged on the side of the base substrate 11 facing the cover plate 2; wherein,

[0089] like Figure 2 As shown, the encapsulation adhesive layer 3 is attached to the peripheral areas of the display substrate 1 and the cover plate 2, that is, Figure 2 The display panel shown is encapsulated in glass;

[0090] like Figure 3 As shown, the encapsulation layer 3 covers the display substrate 1, and the display panel further includes: a first inorganic encapsulation layer 4 arranged between the display substrate 1 and the encapsulation layer 3, and a second inorganic encapsulation layer 5 arranged between the encapsulation layer 3 and the cover plate 2, that is, Figure 3 The display panel shown uses thin film encapsulation.

[0091] In a specific implementation, in the above display panel provided in the embodiment of the present invention, if Figure 2 and Figure 3 As shown, the first electrode 12, the quantum dot light-emitting functional layer 14 and the second electrode 15 constitute a quantum dot light-emitting device, which can be a top-emitting structure or a bottom-emitting structure. The difference between the two is whether the light-emitting direction of the device is emitted through the substrate 11 or away from the substrate 11. For the bottom-emitting structure, the light-emitting direction of the device is emitted through the substrate 11. Specifically, the first electrode 12 close to the substrate 11 includes a transparent film layer or a semi-transparent and semi-reflective film layer, which allows light to pass through, and the second electrode 15 away from the substrate 11 includes an opaque film layer (preferably, a reflective film layer). For the top-emitting structure, the light-emitting direction of the device is away from the substrate. Specifically, the first electrode 12 close to the substrate 11 includes an opaque film layer (preferably, a reflective film layer); the second electrode 15 away from the substrate 1 includes a transparent film layer or a semi-transparent and semi-reflective film layer, which allows light to pass through.

[0092] In a specific implementation, in the above display panel provided in the embodiment of the present invention, if Figure 2 and Figure 3 As shown, the quantum dot light emitting device can be an upright structure or an inverted structure; when it is an upright structure, the first electrode 12 is an anode and the second electrode 15 is a cathode. Figure 4 As shown, the quantum dot light-emitting functional layer 14 may include a hole injection layer 141, a hole transport layer 142, a quantum dot light-emitting layer 143 and an electron transport layer 144 stacked in sequence, the hole injection layer 141 is close to the first electrode 12, and the electron transport layer 144 is close to the second electrode 15; when it is an inverted structure, the first electrode 12 is a cathode, and the second electrode 15 is an anode, as shown in FIG. Figure 5 As shown, the quantum dot light-emitting functional layer 14 may include an electron transport layer 144, a quantum dot light-emitting layer 143, a hole transport layer 142 and a hole injection layer 141 which are stacked in sequence, the electron transport layer 144 is close to the first electrode 12, and the hole injection layer 141 is close to the second electrode 15.

[0093] Specifically, the difference between the upright structure and the inverted structure lies in the different order of film layer production, specifically: the upright structure is to form a first electrode 12 (anode), an electron transport layer 144, a quantum dot light-emitting layer 143, a hole transport layer 142, a hole injection layer 141 and a second electrode 15 (cathode) in sequence on the base substrate 11; the inverted structure is to form a first electrode 12 (cathode), an electron transport layer 144, a quantum dot light-emitting layer 143, a hole transport layer 142, a hole injection layer 141 and a second electrode 15 (anode) in sequence on the base substrate 11.

[0094] In a specific implementation, in the above-mentioned display panel provided by the embodiment of the present invention, the quantum dot light-emitting layer may include a red quantum dot light-emitting layer, a green quantum dot light-emitting layer and a blue quantum dot light-emitting layer to form a color display of the display panel.

[0095] In a specific implementation, in the above-mentioned display panel provided in an embodiment of the present invention, the material of the quantum dot light-emitting layer includes but is not limited to quantum dot materials such as CdS, CdSe, ZnSe, InP, PbS, CsPbCl3, CsPbBr3, CsPbI3, CdS / ZnS, CdSe / ZnSe, CdSe / ZnS, ZnSe, InP / ZnS, PbS / ZnS, CsPbCl3 / ZnS, CsPbBr3 / ZnS or CsPhI3 / ZnS.

[0096] Below Figure 2 Taking the display panel shown as an example and taking the quantum dot light-emitting device as an upright structure as an example, a method for manufacturing the display panel is described, which may specifically include the following steps:

[0097] (1) A first electrode is deposited on a substrate. The substrate may be glass or a flexible PET substrate. The first electrode may be a transparent ITO, FTO or conductive polymer, or an opaque metal electrode such as Al or Ag.

[0098] (2) A pixel defining layer having a plurality of pixel openings is formed on the first electrode, and a hole injection layer is deposited in each pixel opening by spin coating or magnetron sputtering. The material of the hole injection layer can be PEDOT:PSS, MoOx, NiOx, WOx, VOx, etc., and the thickness of the hole injection layer is between 20nm and 100nm.

[0099] (3) Depositing a layer of hole transport material thin film (such as TFB material) on the hole injection layer.

[0100] (4) A layer of red quantum dot material is deposited on the hole transport film, and cross-linked and developed in the red pixel opening to form a patterned hole transport layer and a red quantum dot layer in the red pixel opening. The thickness of the red quantum dot layer can be 20nm-50nm.

[0101] (5) Depositing a layer of hole transport material thin film (such as TFB material) on the red quantum dot layer.

[0102] (6) A layer of green quantum dot material is deposited on the hole transport film, and cross-linked and developed in the green pixel opening to form a patterned hole transport layer and a green quantum dot layer in the green pixel opening. The thickness of the green quantum dot layer can be 20nm-50nm.

[0103] (7) Depositing a layer of hole transport material thin film (such as TFB material) on the green quantum dot layer.

[0104] (8) A layer of blue quantum dot material is deposited on the hole transport film, and cross-linked and developed in the blue pixel opening to form a patterned hole transport layer and a blue quantum dot layer in the blue pixel opening. The thickness of the blue quantum dot layer can be 20nm-50nm.

[0105] (9) Depositing an electron transport layer (such as ZnO material) on the quantum dot light-emitting layer.

[0106] (10) A second electrode is deposited on the electron transport layer. The material of the second electrode may be metal Al, Ag, etc., or IZO may be deposited by magnetron sputtering. The thickness of the second electrode may be 10 nm-100 nm.

[0107] It should be noted that the above method for manufacturing each film layer is the same as that in the related art.

[0108] (11) The above-mentioned packaging adhesive material provided in the embodiment of the present invention is used to bond the cover plate and the display substrate in an inert gas environment, and the packaging adhesive material is cured by ultraviolet irradiation, so that the peripheral areas of the display substrate and the cover plate are bonded together through the packaging adhesive layer, thereby achieving the function of protecting the device.

[0109] Specifically, when the peripheral area of ​​the display substrate and the cover plate is glass-sealed in the above step (11), the encapsulation adhesive material used may include: ethylene glycol methacrylate (active diluent, 10%-20%), ethylene glycol dimethacrylate (active diluent, 5%-10%), dimethyl diheptene (active diluent, 1%-5%, or other monoolefins, C8-C12), trimethoxy [3- (oxiranylmethoxy) propyl] silane (photocurable oligomer, 5%-10%), phenolic epoxy resin (photocurable oligomer, 50%-70%), triaryl sulfonium hexafluorophosphate (photoinitiator, 1%-2%); wherein, in the above main components, a fourth type of substance is added, namely: 0.1%-5% of acrylic acid monomer, or short-chain carboxylic acid such as isobutyric acid and methacrylic acid. In this embodiment, the proportion of acrylic acid monomer added is 1.5%. Since the mass fraction of the carboxylic acid monomer (acrylic acid monomer) is very small and the composition of the carboxylic acid monomer is fixed, the content of the released carboxylic acid monomer will not exceed the standard during the UV curing process. The carboxylic acid monomer combines with the defects on the surface of the quantum dot light-emitting layer (QD), that is, the carboxyl group passivates the defects, thereby improving the efficiency of the device. Moreover, after a small amount of carboxylic acid monomer passivates the QD, no more carboxylic acid monomer will react with the electron transport layer and metal electrodes in the device, thereby not causing corrosion to the device and not destroying the device structure.

[0110] The following uses Comparative Example 1, Comparative Example 2, Comparative Example 3, Example 1 (using the packaging glue material of the present invention) and Example 2 (using the packaging glue material of the present invention) to illustrate that the packaging glue material provided by the embodiments of the present invention can be used to produce a display panel with good device morphology and improved device efficiency.

[0111] Comparative Example 1: The display substrate and the cover plate are not packaged and tested in a glove box. Fig. 6A As shown, Fig. 6A The morphology of the quantum dot light-emitting device shows that the device morphology is uniform due to the absence of acrylic acid corrosion. Figure 6B As shown, Figure 6B is the efficiency of the quantum dot light-emitting device. The horizontal axis is voltage (Voltage) and the vertical axis is current efficiency (Currentefficiency). It can be seen that the efficiency of the device is low.

[0112] Comparative Example 2: The encapsulation adhesive materials used may include: ethylene glycol methacrylate (active diluent, 10%-20%), ethylene glycol dimethacrylate (active diluent, 5%-10%), dimethyl diheptene (active diluent, 1%-5%, or other monoolefins, C8-C12), trimethoxy [3- (oxiranylmethoxy) propyl] silane (photocurable oligomer, 5%-10%), phenolic epoxy resin (photocurable oligomer, 50%-70%), triaryl sulfonium hexafluorophosphate (photoinitiator, 1%-2%). Fig. 7A As shown, Fig. 7A The morphology of the quantum dot light-emitting device is shown in Figure 1. It can be seen that the device morphology is uniform because no acrylic acid is added to the encapsulation material. Figure 7B As shown, Figure 7B This is the efficiency of quantum dot light-emitting devices. It can be seen that the device efficiency is still relatively low.

[0113] Comparative Example 3: The encapsulation adhesive materials used may include: ethylene glycol methacrylate (10%-20%), ethylene glycol dimethacrylate (5%-10%), dimethyl diheptene (1%-5%, or other monoolefins, C8-C12), trimethoxy [3- (oxiranylmethoxy) propyl] silane (5%-10%), phenolic epoxy resin (50%-70%), triaryl sulfonium hexafluorophosphate (photoinitiator, 1%-2%). Among them, in the above main components, 15% of acrylic acid monomer is added, and the device morphology deteriorates, such as Figure 8 shown.

[0114] Example 1: Ethylene glycol methacrylate (active diluent, 10%-20%), ethylene glycol dimethacrylate (active diluent, 5%-10%), dimethyldiheptene (active diluent, 1%-5%, or other monoolefins, C8-C12), trimethoxy [3- (oxiranylmethoxy) propyl] silane (photocurable oligomer, 5%-10%), phenolic epoxy resin (photocurable oligomer, 50%-70%), triarylsulfonium hexafluorophosphate (photoinitiator, 1%-2%); wherein, in the above main components, a fourth type of substance is added, namely: 0.1%-5% content of acrylic acid monomer, or short-chain carboxylic acid monomers such as isobutyric acid and methacrylic acid. In this embodiment, the proportion of acrylic acid monomer added is 1.5%, and the device morphology is as follows: Fig. 9A As shown, the device morphology is uniform; the device efficiency is shown Fig. 9B As shown, the device efficiency is significantly improved compared with Comparative Examples 1 and 2.

[0115] Example 2: Ethylene glycol methacrylate (active diluent, 10%-20%), ethylene glycol dimethacrylate (active diluent, 5%-10%), dimethyldiheptene (active diluent, 1%-5%, or other monoolefins, C8-C12), trimethoxy [3- (oxiranylmethoxy) propyl] silane (photocurable oligomer, 5%-10%), phenolic epoxy resin (photocurable oligomer, 50%-70%), triarylsulfonium hexafluorophosphate (photoinitiator, 1%-2%); wherein, in the above main components, a fourth type of substance is added, namely: 0.1%-5% of long-chain carboxylic acids such as oleic acid. Since the acidity of long-chain carboxylic acid monomers is very weak, the activity of reacting with the electron transport layer and metal in the device is very low, which can further reduce the damage to the device morphology.

[0116] Therefore, it can be concluded from the above comparative examples 1-3 and embodiments 1-2 that when the display substrate and the cover plate are packaged using the packaging adhesive material provided by the embodiments of the present invention, a display panel with good device morphology and high device efficiency can be obtained.

[0117] It should be noted that the above-mentioned comparative examples and embodiments of the present invention take glass packaging as an example, which is of course also applicable to thin film packaging. Based on the same reason, when the display substrate and cover plate of the embodiment of the present invention are packaged with thin film, a display panel with good device morphology and high device efficiency can also be obtained.

[0118] The above-mentioned encapsulation glue material and display panel provided by the embodiment of the present invention adopt non-acrylic photocurable oligomers as the main material of the encapsulation glue material. When the encapsulation glue material is used to encapsulate the device of the QLED display panel, when the encapsulation glue material is cured by ultraviolet irradiation, the non-acrylic photocurable oligomer provided by the present invention will not release a large amount of acrylic acid, so the device morphology of the QLED display panel will not be degraded; and because the encapsulation glue material of the present invention adds carboxylic acid monomers, by strictly controlling the content of carboxylic acid monomers, during the ultraviolet curing process, the small amount of carboxylic acid monomers volatilize to the QD surface in the device, which can play a role in passivating the surface defects of the QD, thereby improving the efficiency of the device. Therefore, when the encapsulation glue material provided by the embodiment of the present invention is used to encapsulate the device, it can be achieved that the device morphology will not be degraded on the basis of improving the efficiency of the device, thereby improving the life of the display panel.

[0119] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0120] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A packaging adhesive material, characterized in that: It includes non-acrylic photocurable oligomers, carboxylic acid monomers, photoinitiators and reactive diluents.

2. The packaging adhesive material according to claim 1, characterized in that: The mass fraction of the non-acrylic light-curable oligomer is 50% to 80%, the mass fraction of the carboxylic acid monomer is 0.1% to 5%, the mass fraction of the photoinitiator is less than 5%, and the mass fraction of the active diluent is 10% to 50%.

3. The packaging adhesive material according to claim 1, characterized in that: The carboxylic acid monomer includes at least one of acrylic acid monomer, isobutyric acid, methacrylic acid, and a carboxylic acid monomer having a carbon chain length of 8 to 18 carbon atoms.

4. The packaging adhesive material according to any one of claims 1 to 3, characterized in that: The non-acrylic light-curable oligomer includes at least one of unsaturated polyester, polyurethane, epoxy resin, and silicone oligomer.

5. The packaging adhesive material according to claim 4, characterized in that: The unsaturated polyester has the following structural formula: Wherein, R1 is a chain hydrocarbon or an aromatic hydrocarbon.

6. The packaging adhesive material according to claim 4, characterized in that: The polyurethane has the following structural formula: Among them, R2 is a chain hydrocarbon group, an aromatic group or a cyclic hydrocarbon group, R3 is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, R4 is a connecting group including 2 to 6 carbon atoms, and R5 is a vinyl group or an epoxy group.

7. The packaging adhesive material according to claim 4, characterized in that: The epoxy resin includes glycidyl epoxy resin, aliphatic epoxy resin or phenolic epoxy resin.

8. The packaging adhesive material according to claim 4, characterized in that: The organosilicon oligomer has the following structural formula: Wherein, R6 is a chain hydrocarbon group or a chain hydrocarbon oxy group, R7 is a connecting group including 2 to 6 carbon atoms, and R8 is a vinyl group or an epoxy group.

9. The packaging adhesive material according to any one of claims 1 to 3, characterized in that: The photoinitiator includes at least one of a free radical photoinitiator and a cationic photoinitiator.

10. The packaging adhesive material according to claim 9, characterized in that: The free radical photoinitiator includes benzophenone and its derivatives, thioxanthone, anthraquinone, benzoin and its derivatives, benzil derivatives, dialkoxyacetophenone, α-hydroxyalkyl phenone, α-aminoalkyl phenone, acylphosphine oxide, and the cationic photoinitiator includes diaryl iodonium salt, triaryl sulfonium salt, aryl ferrocenium salt.

11. The packaging adhesive material according to any one of claims 1 to 3, characterized in that: The reactive diluent molecule contains at least one carbon-carbon double bond and / or one epoxy group.

12. The packaging adhesive material according to claim 11, characterized in that: The active diluent includes at least one of acrylates, methacrylates, vinyls, n-alcohol diacrylates, n-alcohol triacrylates, n-alcohol tetraacrylates, ..., n-alcohol m-acrylates, etc., wherein n=2-4, m=2-8.

13. The packaging adhesive material according to claim 12, characterized in that: The acrylic acid esters include n-butyl acrylate, isooctyl acrylate, isodecyl acrylate, lauryl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate, isobornyl acrylate, tetrahydrofuranyl methyl acrylate or phenoxyethyl acrylate; The methacrylates include hydroxyethyl methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate, isobornyl methacrylate or tetrahydrofuran methyl methacrylate; The vinyls include styrene, vinyl acetate, N-vinyl pyrrolidone or long-chain olefins.

14. A display panel, characterized in that: It comprises a display substrate and a cover plate which are arranged opposite to each other, wherein a packaging glue layer formed by the packaging glue material according to any one of claims 1 to 13 is arranged between the display substrate and the cover plate.

15. The display panel according to claim 14, wherein: The display substrate comprises a base substrate and a first electrode, a pixel defining layer, a quantum dot light-emitting functional layer and a second electrode arranged on the side of the base substrate facing the cover plate; wherein, The packaging adhesive layer is bonded to the peripheral areas of the display substrate and the cover plate; Alternatively, the encapsulation layer covers the display substrate, and the display panel further comprises: a first inorganic encapsulation layer disposed between the display substrate and the encapsulation layer, and a second inorganic encapsulation layer disposed between the encapsulation layer and the cover plate.

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