Display apparatus

Abstract

To resolve connection failure of a light-emitting element.SOLUTION: A display apparatus includes: a substrate including a plurality of sub pixels; a thin-film transistor disposed on the substrate; an adhesive layer disposed on the thin-film transistor and including a first region and a second region having tanδ value higher than that of the first region; and a plurality of light-emitting elements disposed in the first region of the adhesive layer, corresponding to the sub pixels.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present specification relates to a display device and a manufacturing method thereof, and more particularly to a display device in which adhesion defects of light emitting diodes are improved. [Background technology]

[0002] Display devices used in computer monitors, TVs, mobile phones, etc. include organic light-emitting displays (OLEDs), which emit light themselves, and liquid crystal displays (LCDs), which require a separate light source.

[0003] Display devices are now used in a wide range of applications, from computer monitors and TVs to personal portable devices, and research is underway to develop display devices that have a large display area while being reduced in volume and weight.

[0004] In recent years, display devices including light-emitting elements (light-emitting diodes) have been attracting attention as next-generation display devices. Light-emitting elements are made of inorganic materials rather than organic materials, and therefore have excellent reliability and a longer lifespan than liquid crystal display devices and organic light-emitting display devices. Furthermore, light-emitting elements not only have a fast lighting speed, but also excellent luminous efficiency, strong impact resistance, excellent stability, and can display high-brightness images. Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by this specification is to prevent transfer defects that occur in the process of transferring light-emitting elements to a display panel.

[0006] Another problem to be solved by the present specification is to improve the adhesive strength between the light emitting element and the adhesive layer.

[0007] Another problem to be solved by the present specification is to provide a display device that has an excellent transfer yield and allows the stamp to be used several times.

[0008] The objects of this specification are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0009] A display device according to an embodiment of the present specification includes a substrate including a plurality of sub-pixels, a thin film transistor disposed on the substrate, an adhesive layer disposed on the thin film transistor and including a first region and a second region having a tan δ value higher than that of the first region, and a light-emitting element disposed in the first region of the adhesive layer corresponding to the plurality of sub-pixels, wherein the tan δ value is N / mm 2 It is a dimensionless value obtained by dividing the indentation hardness value calculated in units by the indentation elastic modulus value calculated in units of MPa.

[0010] Further details of the embodiments are included in the detailed description and drawings. [Effects of the Invention]

[0011] The present invention can eliminate the problem of light emitting elements being transferred to undesired areas during the transfer process of the light emitting elements.

[0012] The present invention can reduce transfer errors of light emitting devices and improve process yields.

[0013] The present specification can significantly reduce the problem of a decrease in adhesive strength between the light emitting device and the adhesive layer or the visibility of the boundary of the light emitting device due to gaps generated by the uneven pattern formed on the underside of the light emitting device.

[0014] The effects of this specification are not limited to the examples given above, and various other effects are included within this specification. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic configuration diagram of a display device according to an embodiment of the present specification. [Figure 2] 1 is a cross-sectional view of a display device according to an embodiment of the present specification. [Figure 3] FIG. 10 is a schematic cross-sectional view illustrating a display device according to another embodiment of the present specification. [Figure 4] 1 is a flowchart illustrating a method for manufacturing a display device according to an embodiment of the present specification. [Figure 5a] 1A to 1C are cross-sectional views illustrating steps in a method for manufacturing a display device according to an embodiment of the present invention. [Figure 5b] 1A to 1C are cross-sectional views illustrating steps in a method for manufacturing a display device according to an embodiment of the present invention. [Figure 5c] 1A to 1C are cross-sectional views illustrating steps in a method for manufacturing a display device according to an embodiment of the present invention. [Figure 5d] 1A to 1C are cross-sectional views illustrating steps in a method for manufacturing a display device according to an embodiment of the present invention. [Figure 6a] 1 is an image of a cross section between an adhesive layer and a light emitting element in Comparative Example 1 and Example 1. [Figure 6b] 1 is an image of a cross section between an adhesive layer and a light emitting element in Comparative Example 1 and Example 1. [Figure 7a] 1 shows images obtained by evaluating transfer defects in Comparative Example 1 and Example 1. [Figure 7b] 1 shows images obtained by evaluating transfer defects in Comparative Example 1 and Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0016] The advantages and features of the present invention, and methods for achieving them, will become more apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. The embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully convey the scope of the present invention to those skilled in the art.

[0017] The shapes, areas, ratios, angles, numbers, etc. disclosed in the drawings for illustrating the embodiments of this specification are illustrative only and are not intended to limit the scope of this specification. The same reference symbols refer to the same elements throughout this specification. Furthermore, when describing this specification, if it is deemed that a detailed description of related prior art would unnecessarily obscure the gist of this specification, such a detailed description will be omitted. When using words such as "include," "have," and "be made" in this specification, other parts may be added unless "only" is used. When describing an element in the singular, this also includes the plural unless otherwise explicitly stated.

[0018] When interpreting elements, they are interpreted as including a margin of error even if there is no other explicit description.

[0019] When describing a positional relationship, for example, when describing the positional relationship of two parts using "above," "at the top," "below," "next to," etc., one or more other parts may be located between the two parts, as long as "immediately" or "directly" is not used.

[0020] When an element or layer is referred to as "on" another element or layer, it includes the case where the element or layer is directly on top of the other element or layer, or where there are other layers or elements interposed therebetween.

[0021] Furthermore, although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, a first component referred to below may be a second component within the technical concept of this specification.

[0022] Like reference numbers refer to like elements throughout the specification.

[0023] The area and thickness of each component shown in the drawings are shown for convenience of explanation, and the present specification is not necessarily limited to the area and thickness of the components shown.

[0024] The features of the various embodiments of this specification may be partially or wholly combined or combined with each other, may be technically interlocked and driven in various ways, and each embodiment may be implemented independently of the other or may be implemented together in a related relationship.

[0025] In the following, the present specification will be described with reference to the drawings.

[0026] 1 is a schematic diagram of a display device according to an embodiment of the present disclosure, in which, for convenience of explanation, only a display panel PN, a gate driver GD, a data driver DD, and a timing controller TC are shown among various components of the display device 100.

[0027] Referring to FIG. 1, the display device 100 includes a display panel PN including a plurality of sub-pixels SP, a gate driver GD and a data driver DD that supply various signals to the display panel PN, and a timing controller TC that controls the gate driver GD and the data driver DD.

[0028] The gate driver GD supplies a plurality of scan signals to a plurality of scan lines SL in response to a plurality of gate control signals provided by the timing controller TC. Although one gate driver GD is shown as being spaced apart from one side of the display panel PN in FIG. 1, the number and arrangement of the gate drivers GD are not limited thereto.

[0029] The data driver DD converts image data input from the timing controller TC into data voltages using a reference gamma voltage in response to a plurality of data control signals provided from the timing controller TC, and supplies the converted data voltages to a plurality of data lines DL.

[0030] The timing controller TC aligns externally input image data and supplies it to the data driver DD. The timing controller TC can generate gate control signals and data control signals using externally input synchronization signals, such as a dot clock signal, a data enable signal, and horizontal / vertical synchronization signals. The timing controller TC can then supply the generated gate control signals and data control signals to the gate driver GD and the data driver DD, respectively, to control the gate driver GD and the data driver DD.

[0031] The display panel PN is configured to display an image to a user and includes a plurality of sub-pixels SP. A plurality of scan lines SL and a plurality of data lines DL cross each other in the display panel PN, and each of the sub-pixels SP is connected to the scan lines SL and the data lines DL. In addition, although not shown in the drawing, each of the sub-pixels SP may be connected to a high potential power line, a low potential power line, a reference line, etc.

[0032] A display area AA and a non-display area NA surrounding the display area AA can be defined on the display panel PN.

[0033] The display area AA is an area where an image is displayed on the display device 100. A plurality of sub-pixels SP constituting a plurality of pixels and a circuit for driving the plurality of sub-pixels SP may be arranged in the display area AA. The plurality of sub-pixels SP is the smallest unit constituting the display area AA, and n sub-pixels SP may form one pixel. Each of the plurality of sub-pixels SP may be arranged with a light-emitting element and a thin film transistor for driving the light-emitting element. The plurality of light-emitting elements may be defined differently depending on the type of the display panel PN. For example, if the display panel PN is an inorganic light-emitting display panel, the light-emitting element may be a light-emitting diode or a micro light-emitting diode.

[0034] A plurality of wirings for transmitting various signals to the subpixels SP are arranged in the display area AA. For example, the wirings may include a plurality of data wirings DL for supplying data voltages to the subpixels SP, and a plurality of scan wirings SL for supplying scan signals to the subpixels SP. The scan wirings SL may extend in one direction from the display area AA and be connected to the subpixels SP, and the data wirings DL may extend in a direction different from the one direction from the display area AA and be connected to the subpixels SP. In addition, low-potential power supply wirings, high-potential power supply wirings, etc. may also be arranged in the display area AA, but are not limited thereto.

[0035] The non-display area NA is an area where no image is displayed and may be defined as an area extending from the display area AA. Link wiring and pad electrodes for transmitting signals to the sub-pixels SP of the display area AA, as well as driving ICs such as gate driver ICs and data driver ICs may be arranged in the non-display area NA.

[0036] However, the non-display area NA may be located on the rear surface of the display panel PN, that is, on a surface without sub-pixels SP, or may be omitted, and is not limited to what is shown in the drawings.

[0037] Meanwhile, drivers such as the gate driver GD, data driver DD, and timing controller TC can be connected to the display panel PN in various ways. For example, the gate driver GD may be mounted in the non-display area NA using a GIP (Gate In Panel) method, or may be mounted between a plurality of sub-pixels SP in the display area AA using a GIA (Gate In Active Area) method. For example, the data driver DD and timing controller TC may be formed on a separate flexible film and printed circuit board, and the flexible film and printed circuit board may be bonded to pad electrodes formed in the non-display area NA of the display panel PN to electrically connect the data driver DD and timing controller TC to the display panel PN.

[0038] If the gate driver GD is implemented using the GIP method and the data driver DD and timing controller TC transmit signals to the display panel PN through pad electrodes in the non-display area NA, the area of ​​the non-display area NA for arranging the gate driver GD and pad electrodes needs to be larger than a certain level, which may increase the bezel.

[0039] Alternatively, if the gate driver GD is mounted within the display area AA using the GIA method, and side wiring is formed to connect signal wiring on the front side of the display panel PN to pad electrodes on the rear side of the display panel PN, and a flexible film and a printed circuit board are bonded to the rear side of the display panel PN, the non-display area NA on the front side of the display panel PN can be minimized. In other words, if the gate driver GD, data driver DD, and timing controller TC are connected to the display panel PN in the above manner, it may be possible to achieve a zero bezel, which is essentially a bezel-less display.

[0040] FIG. 2 is a cross-sectional view of a display device according to an embodiment of the present specification.

[0041] The substrate 110 is a substrate that supports components disposed on the upper portion of the display device 100 and may be an insulating substrate. A plurality of sub-pixels SP may be formed on the substrate 110 to display an image. For example, the substrate 110 may be made of glass, resin, or the like. The substrate 110 may also be made of a polymer or plastic. In some embodiments, the substrate 110 may be made of a flexible plastic material.

[0042] A pixel circuit for driving a light emitting element is disposed in each of the plurality of sub-pixels SP on the substrate 110. The pixel circuit may include a plurality of thin film transistors and a plurality of capacitors. For convenience of explanation, FIG. 2 shows only the driving transistor DT, the first capacitor C1, and the second capacitor C2 of the pixel circuit configuration, but the pixel circuit may further include, but is not limited to, a switching transistor, a sensing transistor, a light emitting control transistor, etc.

[0043] First, a light-shielding layer BSM is disposed on the substrate 110. The light-shielding layer BSM can block light incident on the active layers of the transistors to minimize leakage current. For example, the light-shielding layer BSM is disposed below the active layer ACT of the driving transistor DT to block light incident on the active layer ACT. If light were to be irradiated onto the active layer ACT, leakage current would occur, reducing the reliability of the transistor. Therefore, by disposing the light-shielding layer BSM on the substrate 110, the reliability of the driving transistor DT can be improved. The light-shielding layer BSM can be made of an opaque conductive material, such as, but not limited to, copper (Cu), aluminum (Al), molybdenum (Mo), nickel (Ni), titanium (Ti), chromium (Cr), or an alloy thereof.

[0044] A buffer layer 111 is disposed on the light-shielding layer BSM. The buffer layer 111 can reduce the penetration of moisture or impurities through the substrate 110. The buffer layer 111 can be formed of, for example, but not limited to, a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx). However, the buffer layer 111 may be omitted depending on the type of substrate 110 or the type of thin film transistor, and is not limited thereto.

[0045] On the buffer layer 111, a drive transistor DT including an active layer ACT, a gate electrode GE, a source electrode SE, and a drain electrode DE is disposed.

[0046] First, the active layer ACT of the driving transistor DT is disposed on the buffer layer 111. The active layer ACT may be made of a semiconductor material such as, but not limited to, an oxide semiconductor, amorphous silicon, or polysilicon. Although not shown in the drawing, other transistors such as a switching transistor, a sensing transistor, an emission control transistor, etc. other than the driving transistor DT may also be disposed, and the active layers of these transistors may also be made of a semiconductor material such as, but not limited to, an oxide semiconductor, amorphous silicon, or polysilicon. In addition, the active layers of transistors included in the pixel circuit, such as the driving transistor DT, the switching transistor, the sensing transistor, the emission control transistor, etc., may be made of the same material or different materials.

[0047] A gate insulating layer 112 is disposed on the active layer ACT. The gate insulating layer 112 is an insulating layer for electrically insulating the active layer ACT from the gate electrode GE, and may be composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

[0048] A gate electrode GE is disposed on the gate insulating layer 112. The gate electrode GE may be made of a conductive material such as, but not limited to, copper (Cu), aluminum (Al), molybdenum (Mo), nickel (Ni), titanium (Ti), chromium (Cr), or an alloy thereof.

[0049] A first interlayer insulating layer 113 and a second interlayer insulating layer 114 are disposed on the gate electrode GE. Contact holes are formed in the first interlayer insulating layer 113 and the second interlayer insulating layer 114 to connect the source electrode SE and the drain electrode DE to the active layer ACT, respectively. The first interlayer insulating layer 113 and the second interlayer insulating layer 114 are insulating layers for protecting the underlying components and may be formed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), but are not limited thereto.

[0050] A source electrode SE and a drain electrode DE electrically connected to the active layer ACT are disposed on the second interlayer insulating layer 114. The source electrode SE is connected to the second capacitor C2 and the first electrode 134 of the light emitting element 130, and the drain electrode DE is connected to other components of the pixel circuit. The source electrode SE and the drain electrode DE may be made of a conductive material such as, but not limited to, copper (Cu), aluminum (Al), molybdenum (Mo), nickel (Ni), titanium (Ti), chromium (Cr), or an alloy thereof.

[0051] Next, the first capacitor C1 is disposed on the gate insulating layer 112. The first capacitor C1 includes a 1-1st capacitor electrode C1a and a 1-2nd capacitor electrode C1b.

[0052] First, the 1-1st capacitor electrode C1a is disposed on the gate insulating layer 112. The 1-1st capacitor electrode C1a may be integrated with the gate electrode GE of the driving transistor DT.

[0053] The 1-2 capacitor electrode C1b is disposed on the first interlayer insulating layer 113. The 1-2 capacitor electrode C1b is disposed so as to overlap the 1-1 capacitor electrode C1a with the first interlayer insulating layer 113 sandwiched therebetween.

[0054] Therefore, the first capacitor C1 is connected to the gate electrode GE of the driving transistor DT and can maintain the voltage of the gate electrode GE of the driving transistor DT for a certain period of time.

[0055] Next, a second capacitor C2 is disposed on the substrate 110. The second capacitor C2 includes a 2-1 capacitor electrode C2a, a 2-2 capacitor electrode C2b, and a 2-3 capacitor electrode C2c. The second capacitor C2 includes a 2-1 capacitor electrode C2a that is a lower capacitor electrode, a 2-2 capacitor electrode C2b that is a middle capacitor electrode, and a 2-3 capacitor electrode C2c that is an upper capacitor electrode.

[0056] The 2-1st capacitor electrode C2a is disposed on the substrate 110. The 2-1st capacitor electrode C2a may be disposed in the same layer as the light-shielding layer BSM and may be made of the same material.

[0057] A 2-2 capacitor electrode C2b is disposed on the buffer layer 111 and the gate insulating layer 112. The 2-2 capacitor electrode C2b may be disposed in the same layer as the gate electrode GE and may be made of the same material as the gate electrode GE.

[0058] The 2-3 capacitor electrode C2c is disposed on the first interlayer insulating layer 113. The 2-3 capacitor electrode C2c may include a first layer C2c1 and a second layer C2c2. The first layer C2c1 of the 2-3 capacitor electrode C2c may be in the same layer and made of the same material as the 1-2 capacitor electrode C1b. The first layer C2c1 may be disposed to overlap the 2-1 capacitor electrode C2a and the 2-2 capacitor electrode C2b with the first interlayer insulating layer 113 sandwiched therebetween.

[0059] The second layer C2c2 of the second-third capacitor electrode C2c is disposed on the second interlayer insulating layer 114. The second layer C2c2 is a portion extending from the source electrode SE of the driving transistor DT and can be connected to the first layer C2c1 through a contact hole in the second interlayer insulating layer 114.

[0060] Therefore, the second capacitor C2 is electrically connected between the source electrode SE of the driving transistor DT and the light-emitting element 130, which can increase the capacitance inherent in the light-emitting element 130 and allow the light-emitting element 130 to emit light with higher brightness.

[0061] A first passivation layer 115a is disposed on the driving transistor DT, the first capacitor C1, and the second capacitor C2. The first passivation layer 115a is an insulating layer for protecting the components below the first passivation layer 115a and may be made of an inorganic material such as, but not limited to, silicon oxide (SiOx) or silicon nitride (SiNx).

[0062] A first planarization layer 116a is disposed on the first passivation layer 115a. The first planarization layer 116a can planarize the upper surface of the pixel circuit including the driving transistor DT. The first planarization layer 116a can be configured as a single layer or multiple layers and can be made of, for example, but not limited to, benzocyclobutene or an acrylic organic material.

[0063] A plurality of reflectors RF are disposed on the first planarization layer 116a. The reflectors RF are configured to reflect light emitted from the light emitting elements 130 toward the upper side of the substrate 110 and may be shaped to correspond to each of the subpixels SP. One reflector RF may be disposed to cover most of the area of ​​one subpixel SP. The reflector RF may be electrically connected to the source electrode SE of the driving transistor DT and the second capacitor C2 through a first contact hole CH1 in the first planarization layer 116a and the first passivation layer 115a. Thus, the reflector RF may electrically connect the driving transistor DT and the first electrode 134 of the light emitting element 130. The reflector RF reflects light emitted from the light emitting element 130 and may also serve as an electrode electrically connecting the light emitting element 130 to a pixel circuit. Therefore, the reflector RF may include various conductive layers in consideration of light reflection efficiency and resistance. For example, the reflector RF may use an opaque conductive layer such as silver (Ag), aluminum (Al), molybdenum (Mo), titanium (Ti) or an alloy thereof together with a transparent conductive layer such as ITO (Indium Tin Oxide), but the structure of the reflector RF is not limited thereto.

[0064] A second passivation layer 115b is disposed on the plurality of reflectors RF. The second passivation layer 115b is an insulating layer for protecting the structure below the second passivation layer 115b, and may be composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

[0065] An adhesive layer 120 is disposed on the second passivation layer 115b. The adhesive layer 120 may be formed on the front surface of the substrate 110 to fix the light emitting element 130 disposed on the adhesive layer 120. The adhesive layer 120 may insulate the light emitting element 130 from a reflector RF made of a metal material. The adhesive layer 120 may be disposed to overlap the reflector RF disposed in each of the plurality of sub-pixels SP. The adhesive layer 120 may be separated for each of the plurality of sub-pixels SP to overlap the reflector RF, or may be disposed over the entire second passivation layer 115b. The adhesive layer 120 may also be formed on the front surface of the substrate 110 except for a plurality of pad regions where the first pad electrodes are disposed.

[0066] The adhesive layer 120 includes a first region 121 corresponding to the light emitting element 130 and a second region 122 not corresponding to the light emitting element 130. The first region 121 is an area that adheres to the light emitting element 130 and has sufficient adhesive strength to adhere the light emitting element 130. The second region 122 is an area that does not adhere to the light emitting element 130 and has lower adhesive strength than the first region 121.

[0067] The first region 121 has a low tan δ value, and the second region 122 has a high tan δ value. The tan δ value indicates the balance of viscosity to elasticity of the adhesive layer 120. More specifically, the tan δ value is a function of the indentation hardness (HIT, N / mm 2 ) / Indentation Modulus (EIT, Mpa). That is, the tan δ value is N / mm 2The indentation hardness (HIT) is a dimensionless value obtained by dividing the indentation hardness value calculated in units by the indentation modulus value calculated in units of MPa. In this case, the indentation hardness (HIT) may indicate the indentation hardness at a depth of several tens to several hundreds of nanometers from the surface of the adhesive layer 120. The indentation hardness (HIT) may be related to the plasticity property of the adhesive layer 120, which is the elasticity and plasticity property of the adhesive layer 120. The indentation modulus (EIT) may indicate the indentation modulus at a depth of several tens to several hundreds of nanometers from the surface of the adhesive layer 120. The indentation modulus (EIT) may be related to the elasticity property of the adhesive layer 120, which is the elasticity and plasticity property of the adhesive layer 120. Meanwhile, the indentation hardness (HIT) and the indentation modulus (EIT) may be measured using a nanoindenter according to the ISO 14577 standard.

[0068] Specifically, the tan δ value of the first region 121 may be 0.01 or less, 0.008 or less, or 0.001 to 0.008, and the tan δ value of the second region 122 may be 0.05 or more, 0.1 or more, or 0.08 to 0.2. When the tan δ values ​​of the first region 121 and the second region 122 each satisfy the above ranges, the adhesive strength of the first region 121 is improved, and the adhesive strength of the second region 122 is significantly reduced compared to the first region 121, resulting in a robust surface. This prevents the light emitting element 130 from being transferred to an undesired region, i.e., the second region 122.

[0069] The adhesive layer 120 may be made of a photo-curable adhesive material that can be cured by ultraviolet light. For example, the adhesive layer 120 may be made of an acrylic-based material containing a photosensitive agent. In this case, the first region 121 and the second region 122 of the adhesive layer 120 may be formed from the same adhesive composition. For example, the first region 121 and the second region 122 may be formed by applying the same adhesive composition to a substrate and then partially irradiating it with ultraviolet light.

[0070] More specifically, the adhesive layer 120 may include a binder resin, a functional monomer, and a photosensitizer. For example, the binder resin may be an acrylic resin. The photosensitizer may be at least one selected from an oxime-based and a benzophenone-based photoinitiator. Meanwhile, the functional monomer controls the adhesiveness of the adhesive layer 120 and adjusts the tan δ value. Specifically, the functional monomer includes a low tan δ monomer (A, first functional monomer) and a high tan δ monomer (B, second functional monomer).

[0071] Specifically, the low tan δ monomer (A) is a low molecular weight monomer with high fluidity, which can improve the adhesion of the first region 121 and improve the yield of the transfer process of the light emitting device 130. For example, the low tan δ monomer (A) can be diurethane dimethacrylate, polyethylene glycol dimethacrylate, bisphenol A (EO) 10 diacrylate, bisphenol A (EO) 30 diacrylate, tricyclodecane dimethanol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 300 diacrylate, polyethylene glycol 400 diacrylate, polyethylene glycol 600 diacrylate, polyethylene glycol 1000 diacrylate, tris(2-hydroxyethyl) isocyanurate diacrylate, The surfactant may include, but is not limited to, one or more selected from the group consisting of acrylate, butylated hydroxyanisole, 2,6-di-tert-butyl-4-hydroxymethylphenol, butylated hydroxytoluene, propyl gallate, lauryl gallate, octyl gallate, 2,4,5-trihydroxybutyrophenone, tert-butylhydroquinone, 3-aminophenol, 4-aminophenol, 4-methoxyphenol, 2,3,5-trimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, poly(4-vinylphenol), and 4-bromophenol.

[0072] The high tan δ monomer (B) improves the tan δ value when the adhesive layer 120 is irradiated with ultraviolet light, making the film surface properties robust and preventing the light emitting element 130 from being transferred to the second region 122 during the transfer process of the light emitting element 130. For example, the high tan δ monomer (B) may include, but is not limited to, one or more selected from the group consisting of 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,3-butylene glycol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol tetraacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, pentaerythritol hexaacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipentaerythritol diacrylate, sorbitol triacrylate, bisphenol A diacrylate derivatives, trimethylpropane triacrylate, and methacrylates thereof.

[0073] The content ratio of the low tan δ monomer (A) and the high tan δ monomer (B) may be 3:1 to 1:1. When the content of the low tan δ monomer (A) and the high tan δ monomer (B) satisfies this range, the adhesive strength of the first region 121 is ensured while the adhesive strength of the second region 122 is reduced, and plasticity characteristics may be improved. As a result, in the future transfer process of the light emitting device 130, the transfer yield of the light emitting device 130 to the first region 121 can be improved and the transfer of the light emitting device 130 to the second region 122 can be prevented.

[0074] Meanwhile, the combined content of the functional monomers, low tan δ monomer (A) and high tan δ monomer (B), may be 10 to 70 parts by weight based on 100 parts by weight of the binder resin. If the content of the functional monomers is outside this range based on the binder resin, the adhesive strength of the second region 122 may increase or the adhesive strength of the first region 121 may decrease.

[0075] The first region 121 and the second region 122 of the adhesive layer 120 can be formed by selectively irradiating the adhesive layer 120 with UV light. For example, when UV light is irradiated to a portion of the adhesive layer 120, the tan δ value of the irradiated region is improved by the high tan δ monomer (B), thereby improving the plasticity film surface characteristics. As a result, the region irradiated with UV light will form the second region 122 to which the light emitting element 130 will not be transferred. On the other hand, the region not irradiated with UV light will form the first region 121. The first region 121 has a low tan δ value due to the low tan δ monomer (A), improving adhesive strength. Specific methods for forming the first region 121 and the second region 122 of the adhesive layer 120 will be described later.

[0076] Meanwhile, the first region 121 and the second region 122 of the adhesive layer 120 may be formed from different adhesive compositions. For example, the first region 121 may contain only a low tan δ monomer (A) as a functional monomer, and the second region 122 may contain only a high tan δ monomer (B) as a functional monomer. That is, the first region 121 may be formed from a first composition including a binder resin, a low tan δ monomer (A), and a photosensitizer, and the second region 122 may be formed from a second composition including a binder resin, a high tan δ monomer (B), and a photosensitizer.

[0077] The widths of the first region 121 and the second region 122 of the adhesive layer 120 may be determined taking into consideration the size of the light emitting element 130 and process margins. For example, the widths of the first region 121 and the second region 122 may be, but are not limited to, 20 μm to 200 μm or 50 μm to 150 μm. Meanwhile, the thicknesses of the first region 121 and the second region 122 of the adhesive layer 120 may be, but are not limited to, 2 μm to 5 μm. Furthermore, as will be described later, the thickness of the first region 121 where the light emitting element 130 is disposed may be thicker than the second region 122.

[0078] An upper surface of the first region 121 of the adhesive layer 120 may have a shape that protrudes upward from an upper surface of the second region 122 toward the light emitting element 130. Since the first region 121 has a structure that protrudes upward from the second region 122, the light emitting element 130 can be transferred with a higher yield during the process of transferring and pressing the light emitting element 130 to a display panel.

[0079] Meanwhile, a display device according to another embodiment of the present specification may further include a step structure for the first region 121 of the adhesive layer 120 to have a protruding shape.

[0080] FIG. 3 is a schematic cross-sectional view illustrating a display device according to another embodiment of the present disclosure. Referring to FIG. 3, a step structure 160 including a protrusion protruding toward the light emitting device 130 is disposed below the adhesive layer 120. The step structure 160 is disposed to contact the adhesive layer 120. Due to the protrusion corresponding to the first region 121, the upper surface of the first region 121 may protrude upward relative to the upper surface of the second region 122. The step structure 160 may enable the light emitting device 130 to be transferred to the first region 121 of the adhesive layer 120 with a higher yield. The step structure 160 may be located on the reflector RF and below the light emitting device 130. The step structure 160 may also be formed using the second passivation layer 115b. The step structure 160 may be formed between the second passivation layer 115b and the adhesive layer 120, or between the second passivation layer 115b and the reflector RF.

[0081] A plurality of light emitting elements 130 are disposed on the adhesive layer 120 in each of the plurality of sub-pixels SP. The light emitting elements 130 are elements that emit light in response to an electric current and may include a red light emitting element that emits red light, a green light emitting element that emits green light, and a blue light emitting element, and a combination of these elements may realize light of various colors including white. For example, the light emitting elements 130 may be, but are not limited to, LEDs (Light Emitting Diodes) or micro LEDs.

[0082] Each light emitting element is connected to a driving transistor DT of each sub-pixel and can be driven individually.

[0083] The plurality of light emitting elements 130 include a first semiconductor layer 131 , a light emitting layer 132 , a second semiconductor layer 133 , a first electrode 134 and a second electrode 135 .

[0084] A first semiconductor layer 131 is disposed on the adhesive layer 120, and a second semiconductor layer 133 is disposed on the first semiconductor layer 131. The first semiconductor layer 131 and the second semiconductor layer 133 may be layers formed by doping a specific material with n-type and p-type impurities. For example, the first semiconductor layer 131 and the second semiconductor layer 133 may be layers formed by doping a material such as gallium nitride (GaN), indium aluminum phosphide (InAlP), gallium arsenide (GaAs), etc. with n-type and p-type impurities. The p-type impurities may be magnesium, zinc (Zn), beryllium (Be), etc., and the n-type impurities may be silicon (Si), germanium, tin (Sn), etc., but are not limited thereto.

[0085] A plurality of uneven patterns may be formed on the lower surface of the first semiconductor layer 131 that is in contact with the adhesive layer 120. The uneven patterns may be formed on the lower surface of the first semiconductor layer 131 during the process of manufacturing the light emitting device 130 and the process of primarily transferring the light emitting device 130 to the donor substrate.

[0086] The light emitting layer 132 is disposed between the first semiconductor layer 131 and the second semiconductor layer 133. The light emitting layer 132 can emit light by receiving holes and electrons from the first semiconductor layer 131 and the second semiconductor layer 133. The light emitting layer 132 may have a single layer or a multi-quantum well (MQW) structure and may be made of, for example, indium gallium nitride (InGaN) or gallium nitride (GaN), but is not limited thereto.

[0087] The first electrode 134 is disposed on the first semiconductor layer 131. The first electrode 134 is an electrode for electrically connecting the driving transistor DT and the first semiconductor layer 131. In this case, the first semiconductor layer 131 may be a semiconductor layer doped with n-type impurities, and the first electrode 134 may be a cathode. The first electrode 134 may be disposed on an upper surface of the first semiconductor layer 131 exposed from the light emitting layer 132 and the second semiconductor layer 133. The first electrode 134 may be made of a conductive material, for example, a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), or an opaque conductive material such as titanium (Ti), gold (Au), silver (Ag), copper (Cu), or an alloy thereof, but is not limited thereto.

[0088] The second electrode 135 is disposed on the second semiconductor layer 133. The second electrode 135 may be disposed on an upper surface of the second semiconductor layer 133. The second electrode 135 is an electrode for electrically connecting a high-potential power wiring to the second semiconductor layer 133. In this case, the second semiconductor layer 133 may be a semiconductor layer doped with p-type impurities, and the second electrode 135 may be an anode. The second electrode 135 may be made of a conductive material, for example, a transparent conductive material such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), or an opaque conductive material such as titanium (Ti), gold (Au), silver (Ag), copper (Cu), or an alloy thereof, but is not limited thereto.

[0089] Next, a sealing film 136 is disposed to surround the first semiconductor layer 131, the light emitting layer 132, the second semiconductor layer 133, the first electrode 134, and the second electrode 135. The sealing film 136 is made of an insulating material and can protect the first semiconductor layer 131, the light emitting layer 132, and the second semiconductor layer 133. Contact holes exposing the first electrode 134 and the second electrode 135 are formed in the sealing film 136, so that the first connecting electrode CE1 and the second connecting electrode CE2 can be electrically connected to the first electrode 134 and the second electrode 135.

[0090] Meanwhile, a portion of the side surface of the first semiconductor layer 131 may be exposed from the encapsulation film 136. The light emitting device 130 manufactured on the wafer may be separated from the wafer and transferred to the display panel PN. However, a portion of the encapsulation film 136 may be peeled off during the process of separating the light emitting device 130 from the wafer. For example, a portion of the encapsulation film 136 adjacent to the lower edge of the first semiconductor layer 131 of the light emitting device 130 may be peeled off during the process of separating the light emitting device 130 from the wafer, thereby exposing a portion of the lower side surface of the first semiconductor layer 131 to the outside. However, even if the lower portion of the light emitting device 130 is exposed from the encapsulation film 136, the first connecting electrode CE1 and the second connecting electrode CE2 are formed after the second planarization layer 116b and the third planarization layer 116c covering the side surfaces of the first semiconductor layer 131 are formed, thereby reducing short-circuit defects.

[0091] Next, a second planarization layer 116b and a third planarization layer 116c are disposed on the adhesive layer 120 and the light emitting devices 130. The second planarization layer 116b overlaps a portion of the side surfaces of the light emitting devices 130 to secure and protect the light emitting devices 130. The third planarization layer 116c is formed to cover the second planarization layer 116b and upper portions of the light emitting devices 130, and contact holes exposing the first electrode 134 and the second electrode 135 of the light emitting device 130 may be formed therein. The first electrode 134 and the second electrode 135 of the light emitting device 130 are exposed through the third planarization layer 116c, and the third planarization layer 116c is partially disposed in the region between the first electrode 134 and the second electrode 135 to reduce short-circuit defects. The second planarization layer 116b and the third planarization layer 116c may be configured as a single layer or multiple layers and may be made of, for example, but not limited to, a photoresist or an acrylic organic material.

[0092] Meanwhile, the third planarization layer 116c may cover only the light emitting element 130 and an area adjacent to the light emitting element 130. The third planarization layer 116c may be disposed in an island shape in the area of ​​the subpixel SP surrounded by the bank 140. Thus, the bank 140 may be disposed on a portion of the upper surface of the second planarization layer 116b, and the third planarization layer 116c may be disposed on another portion of the upper surface of the second planarization layer 116b.

[0093] A first connecting electrode CE1 and a second connecting electrode CE2 are disposed on the third planarization layer 116c. The first connecting electrode CE1 electrically connects the second electrode 135 of the light emitting element 130 to a high-potential power line. The first connecting electrode CE1 may be electrically connected to the second electrode 135 of the light emitting element 130 through a contact hole formed in the third planarization layer 116c.

[0094] The second connecting electrode CE2 electrically connects the first electrode 134 of the light emitting element 130 to the driving transistor DT. The second connecting electrode CE2 may be connected to the reflector RF of each of the sub-pixels SP through contact holes formed in the third planarization layer 116c, the second planarization layer 116b, the adhesive layer 120, and the second passivation layer 115b. In this case, the reflector RF is also connected to the source electrode SE of the driving transistor DT, so that the source electrode SE of the driving transistor DT and the first electrode 134 of the light emitting element 130 may be electrically connected to each other.

[0095] Meanwhile, in the drawings, the first electrode 134, the second connecting electrode CE2, and the reflector RF are shown as being electrically connected to the source electrode SE of the driving transistor DT, but the first electrode 134, the second connecting electrode CE2, and the reflector RF may also be connected to the drain electrode DE of the driving transistor DT, and are not limited thereto.

[0096] The bank 140 is disposed on the second planarization layer 116b exposed from the first connecting electrode CE1, the second connecting electrode CE2, and the third planarization layer 116c. The bank 140 may be disposed at a predetermined distance from the light emitting element 130. For example, the bank 140 may be disposed on the second planarization layer 116b at a predetermined distance from the light emitting element 130, or may cover a portion of the second connecting electrode CE2 formed in the third planarization layer 116c and the contact hole of the second planarization layer 116b. The bank 140 may be made of an opaque material to reduce color mixing between the plurality of subpixels SP, for example, but is not limited to, a black resin containing a black component.

[0097] A protective layer 117 is disposed on the first connecting electrode CE1, the second connecting electrode CE2, and the bank 140. The protective layer 117 is a layer for protecting the components below the protective layer 117. The protective layer 117 may be configured as a single layer or multiple layers and may be made of, for example, but not limited to, benzocyclobutene, light-transmitting epoxy, photoresist, or an acrylic organic material.

[0098] The optical film 150 is disposed on the protective layer 117. The optical film 150 may be a functional film that realizes a higher quality image while protecting the display device 100. For example, the optical film 150 may include, but is not limited to, a shatterproof film, an anti-glare film, an anti-reflecting film, a low-reflecting film, a brightness enhancing film (OLED transmittance controllable film), a polarizing plate, or the like.

[0099] A method for manufacturing a display device according to an embodiment of the present specification will be described below.

[0100] 4 is a flowchart illustrating a method for manufacturing a display device according to an embodiment of the present disclosure, and FIGS. 5a and 5d are cross-sectional views illustrating steps in the method for manufacturing a display device according to an embodiment.

[0101] Referring to FIG. 4, a manufacturing method (S100) of a display device according to one embodiment of the present specification includes the steps of: coating an adhesive composition on a display panel to form an adhesive coating layer (S110); irradiating ultraviolet light onto the adhesive coating layer using a mask to form an adhesive layer having a first region and a second region (S120); aligning a donor substrate on which a plurality of light-emitting elements are arranged with the display panel (S130); bonding the donor substrate and the display panel so that the plurality of light-emitting elements correspond to the first region (S140); transferring the plurality of light-emitting elements of the donor substrate to the display panel (S150); and detaching the display panel from the donor substrate (S160).

[0102] 5A, an adhesive composition is coated on a display panel to form an adhesive coating layer 120' (S110). The adhesive composition includes a photo-curable adhesive material, and as described above, includes a low tan δ monomer (A) and a high tan δ monomer (B). The adhesive composition can be coated using a common adhesive coating method such as spin coating or printing, but is not limited thereto.

[0103] 5b, ultraviolet light is irradiated onto the adhesive coating layer 120' using a mask MS to form an adhesive layer including a first region and a second region (S120). By irradiating ultraviolet light onto the adhesive coating layer 120' corresponding to the second region 122 where the light emitting element 130 is not disposed, the adhesive strength and tan δ value can be adjusted.

[0104] 5c, when the compound constituting the adhesive coating layer 120′ in FIG. 5a is irradiated with UV light, the adhesive strength of the region irradiated with UV light through the mask MS decreases and the tan δ value increases, forming a second region 122 to which the light emitting device 130 will not be transferred. Therefore, the adhesive layer 120 including the first region 121 and the second region 122 can be formed by irradiating UV light using the mask MS.

[0105] Referring to FIG. 5d, the donor substrate 200 on which the plurality of light emitting elements 130 are arranged is aligned with the display panel (S130). First, the donor substrate 200 on which the plurality of light emitting elements 130 are arranged is provided. The donor substrate 200 includes a base layer 210, an adhesive layer 220, and a resin layer 230. The base layer 210 is configured to support various components included in the donor substrate 200 and may be made of a material that is at least more rigid than the resin layer 230 to minimize warping of the resin layer 230. The adhesive layer 220 adheres the resin layer 230 to the base layer 210. For example, the adhesive layer 220 may be made of, but is not limited to, an optical clear adhesive (OCA) or a pressure sensitive adhesive (PSA). The adhesive layer 220 may be omitted depending on the design and is not limited thereto. The resin layer 230 includes an area onto which the plurality of light emitting elements 130 formed on the wafer are primarily transferred. The resin layer 230 may be made of a polymer resin having viscoelasticity.

[0106] The donor substrate 200 on which the plurality of light emitting elements 130 are arranged and the display panel are placed in a processing equipment, and then the donor substrate 200 and the display panel placed in the processing equipment are aligned so that they face each other. The display panel is a display panel on which circuits for driving the plurality of light emitting elements 130, such as driving transistors and a plurality of wirings, have been formed. The display panel is also a display panel on which an adhesive layer 120 including a first region 121 and a second region 122 has been formed on the circuits. A plurality of alignment keys may be formed on the display panel and aligned with a plurality of alignment marks formed on the donor substrate. This aligns at least some of the plurality of light emitting elements 130 on the donor substrate 200 to correspond to the first region 121 of the adhesive layer 120 formed on the upper surface of the display panel.

[0107] The donor substrate 200 and the display panel are bonded together (S140) so that the light emitting elements 130 correspond to the first regions 121. The display panel and the donor substrate 200 are bonded together while maintaining the alignment of the display panel and the donor substrate 200.

[0108] Thereafter, the plurality of light emitting elements 130 of the donor substrate 200 are transferred to a display panel (S150). With the display panel and the donor substrate 200 bonded together facing each other, a laser can be selectively irradiated onto only the light emitting elements 130 to be transferred to the display panel among the plurality of light emitting elements 130. The light emitting elements 130 irradiated with the laser can be detached from the donor substrate 200 and transferred to the first region 121 of the adhesive layer 120 formed on the upper surface of the display panel.

[0109] Thereafter, the display panel and the donor substrate 200 are detached, and the donor substrate 200 onto which the light emitting devices 130 are transferred is removed from the processing equipment (S160).

[0110] Typically, display devices including light-emitting elements such as LEDs are manufactured through a process of transferring or stamping display elements from a donor substrate onto a display panel on which driving elements and an adhesive layer are formed. However, in the case of small light-emitting elements such as micro LEDs, problems with transfer are encountered due to their small size, and the picked-up donor substrate cannot be reused multiple times. After transfer or stamping, the existing donor substrate must be detached and a new temporary substrate must be inserted, making the process cumbersome. Furthermore, when transferring the display element, an adhesive layer with locally varying adhesive strength is used to attach the display element to a specific position. In this case, the display element may not be sufficiently attached to the desired transfer position or may be attached to an undesired position.

[0111] A display device according to an embodiment of the present disclosure includes an adhesive layer including a first region and a second region corresponding to a light emitting element. The first region is an area that is bonded to the light emitting element and has a low tan δ value, and the second region is an area that is not bonded to the light emitting element and has a higher tan δ value than the first region. The adhesive layer having such characteristics can reduce process errors that may result in light emitting elements being attached to undesired areas, thereby improving process yield.

[0112] Meanwhile, referring to FIG. 2, a plurality of concave-convex patterns may be formed on the lower surface of the light emitting device. The concave-convex patterns are formed during the process of cutting a semiconductor layer grown on a wafer or primarily transferring it to a donor substrate during the manufacture of the light emitting device. The concave-convex patterns formed on the lower surface of the light emitting device may cause a decrease in adhesive strength with an adhesive layer during secondary transfer from the donor substrate to a display panel. When the light emitting device is secondary transferred to the display panel, the lower surface of the light emitting device on which the concave-convex patterns are formed comes into direct contact with the adhesive layer, and at this time, voids may occur in the concave-convex pattern between the adhesive layer and the light emitting device. The voids formed in the concave-convex pattern significantly reduce the adhesive strength between the adhesive layer and the light emitting device, which may result in transfer defects of the light emitting device.

[0113] In the adhesive layer of the display device according to one embodiment of the present specification, the light emitting element is disposed in a first region having a low tan δ, and in this case, the occurrence of voids between the lower surface of the light emitting element and the adhesive layer can be significantly reduced.

[0114] The effects of the adhesive layer structure will be described in more detail below through examples and comparative examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present specification.

[0115] Example 1 In Example 1, an adhesive composition was prepared containing 15 parts by weight of an acrylic copolymer resin as a binder resin, 5 parts by weight of diurethane dimethacrylate as a low tan δ monomer (A, first functional monomer), 3 parts by weight of pentaerythritol tetraacrylate as a high tan δ monomer (B, second functional monomer), 0.5 parts by weight of 4,4'-bis(dimethylamino)benzophenone as a photosensitizer, and 76.5 parts by weight of propylene glycol monomethyl ether acetate as a solvent. The adhesive composition was coated onto a substrate to a thickness of 3.5 μm, dried in a 40 Pa vacuum chamber for 30 seconds, and then further dried on a 90°C hot plate for 10 seconds. After that, the adhesive composition was exposed to 100 mJ / cm of ultraviolet light using a mask. 2At this time, an adhesive layer was formed in which the thicknesses of the first and second regions were 3.0 μm and 2.7 μm, respectively, and the widths of the first and second regions were 100 μm.

[0116] Comparative Example 1 An adhesive layer was formed in the same manner as in Example 1, except that the adhesive composition did not contain a low tan δ monomer or a high tan δ monomer.

[0117] Experimental Example 1 - Transfer Performance Evaluation Micro LEDs with a width of 20 μm were stamped once on the first region of the adhesive layer according to Example 1 and Comparative Example 1, and the number of micro LEDs transferred to the first region and the number of micro LEDs transferred to the second region were counted. The transfer results are shown in Table 1 below.

[0118] Experimental Example 2 - Transfer characteristic evaluation After the micro LED transfer process, the cross section between the micro LED transferred to the first region and the adhesive layer was photographed using an optical microscope to check for the presence or absence of voids between the micro LED and the adhesive layer. Figures 6a and 6b are images of the cross section between the adhesive layer and the light emitting element in Comparative Example 1 and Example 1.

[0119] In addition, after the micro LED transfer process, the area on the top surface of the display panel where the micro LEDs were attached and the adjacent area were photographed to check whether the uneven pattern formed on the bottom surface of the micro LEDs was visible. Figures 7a and 7b are images used to evaluate transfer defects in Comparative Example 1 and Example 1. [Table 1]

[0120] Referring to Table 1, it was confirmed that Example 1, compared to Comparative Example 1, eliminated the problem of the light emitting device being erroneously transferred to the second region, thereby improving the process yield. Meanwhile, referring to FIG. 6a, it was confirmed that in Comparative Example 1, multiple uneven patterns were formed on the underside of the light emitting device in the cross section, and voids V were formed in the uneven patterns between the adhesive layer and the light emitting device. The height of the voids was 46 cm relative to the height of the uneven patterns, confirming the formation of large voids in the uneven patterns. In contrast, referring to FIG. 6b, it was confirmed that in Example 1, almost no voids were formed in the uneven patterns between the adhesive layer and the light emitting device, and they were barely visible in the image. The height of the voids was 3 cm relative to the height of the uneven patterns, confirming the size of the voids was significantly smaller than in Comparative Example 1.

[0121] 7a, in the case of Comparative Example 1, a luminance difference (8%) occurred at the boundary between the area where the micro LEDs were formed and the area where they were not formed due to the uneven pattern formed on the underside of the micro LEDs, and it was confirmed that the boundary BL of the area where the micro LEDs were formed was visible. In contrast, in the case of Example 1, as confirmed in FIG. 6b, it was confirmed that the formation of voids was negligible, and the boundary of the area where the micro LEDs were formed was not visible to the naked eye.

[0122] Experimental Example 3 - Transfer performance depending on the content of functional monomer In the following, the transfer performance was evaluated by varying the content of low tan δ monomer and high tan δ monomer constituting the functional monomer. The evaluation method was the same as in Experimental Example 1, and the transfer results are shown in Table 2 below.

[0123] Example 2 In Example 2, an adhesive layer was formed in the same manner as in Example 1, except that the contents of diurethane dimethacrylate as the low tan δ monomer (A, first functional monomer) and pentaerythritol tetraacrylate as the high tan δ monomer (B, second functional monomer) were 2 parts by weight and 1 part by weight, respectively.

[0124] Example 3 In Example 3, an adhesive layer was formed in the same manner as in Example 1, except that the contents of diurethane dimethacrylate as the low tan δ monomer (A, first functional monomer) and pentaerythritol tetraacrylate as the high tan δ monomer (B, second functional monomer) were 4 parts by weight and 2 parts by weight, respectively.

[0125] Example 4 In Example 4, an adhesive layer was formed in the same manner as in Example 1, except that the contents of diurethane dimethacrylate as the low tan δ monomer (A, first functional monomer) and pentaerythritol tetraacrylate as the high tan δ monomer (B, second functional monomer) were 6 parts by weight and 3 parts by weight, respectively.

[0126] Comparative Example 2 In Comparative Example 2, an adhesive layer was formed in the same manner as in Example 1, except that only diurethane dimethacrylate was included as the low tan δ monomer (A, first functional monomer) at 2 parts by weight, and no high tan δ monomer (B, second functional monomer) was used.

[0127] Comparative Example 3 In Comparative Example 3, an adhesive layer was formed in the same manner as in Example 1, except that the contents of diurethane dimethacrylate as the low tan δ monomer (A, first functional monomer) and pentaerythritol tetraacrylate as the high tan δ monomer (B, second functional monomer) were 8 parts by weight and 4 parts by weight, respectively. [Table 2]

[0128] Referring to Table 2, it was confirmed that when the high tan δ monomer was not included, the light emitting device was also erroneously transferred to the second region. Also, even when the low tan δ monomer and the high tan δ monomer were included in the same ratio, when the total content of the functional monomer was 70% or more based on the binder resin, it was confirmed that the effect of preventing selective transfer to the second region was somewhat reduced. Display devices according to various embodiments of the present disclosure can be described as follows. A display device according to one embodiment of the present specification includes a substrate including a plurality of subpixels; a thin film transistor disposed on the substrate; an adhesive layer disposed on the thin film transistor and including a first region and a second region having a higher tan δ value than the first region; and a plurality of light-emitting elements disposed in the first region of the adhesive layer corresponding to the plurality of subpixels.

[0129] According to another feature of the present specification, the tan δ value of the first region may be 0.01 or less, and the tan δ value of the second region may be 0.08 to 0.2.

[0130] According to yet another feature herein, the second region may have a higher degree of hardness than the first region.

[0131] According to another feature of the present specification, the adhesive layer may include a binder resin, a photosensitizer, a first functional monomer and a second functional monomer having different tan δ values.

[0132] According to still another feature of the present specification, the first functional monomer is selected from the group consisting of diurethane dimethacrylate, polyethylene glycol dimethacrylate, bisphenol A (EO) 10 diacrylate, bisphenol A (EO) 30 diacrylate, tricyclodecane dimethanol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 300 diacrylate, polyethylene glycol 400 diacrylate, polyethylene glycol 600 diacrylate, polyethylene glycol 1000 diacrylate, tris(2-hydroxyethyl) ) isocyanurate diacrylate, butylated hydroxyanisole, 2,6-di-tert-butyl-4-hydroxymethylphenol, butylated hydroxytoluene, propyl gallate, lauryl gallate, octyl gallate, 2,4,5-trihydroxybutyrophenone, tert-butylhydroquinone, 3-aminophenol, 4-aminophenol, 4-methoxyphenol, 2,3,5-trimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, poly(4-vinylphenol), and 4-bromophenol.

[0133] According to still another feature of the present specification, the second functional monomer may include at least one selected from the group consisting of 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,3-butylene glycol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol tetraacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, pentaerythritol hexaacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipentaerythritol diacrylate, sorbitol triacrylate, bisphenol A diacrylate derivatives, trimethylpropane triacrylate, and methacrylates thereof.

[0134] According to another feature of the present specification, the total content of the functional monomers, including the first functional monomer and the second functional monomer, may be 10 to 70 parts by weight based on 100 parts by weight of the binder resin.

[0135] According to still another feature of the present specification, an upper surface of the first region may protrude further than an upper surface of the second region toward the plurality of light-emitting elements.

[0136] According to another feature of the present specification, the display panel may further include a step structure disposed below the adhesive layer and including protrusions protruding toward the plurality of light emitting devices in correspondence with the first region.

[0137] According to another feature of the present specification, the display device may further include a planarization layer disposed on the thin film transistors, a plurality of reflectors disposed on the planarization layer and connected to the plurality of light-emitting elements, respectively, and a passivation layer disposed between the plurality of reflectors and the adhesive layer, and the step structure may be disposed between the plurality of reflectors and the passivation layer or between the passivation layer and the adhesive layer.

[0138] According to another feature of the present specification, the display device may further include a planarization layer disposed on the thin film transistors; a plurality of reflectors disposed on the planarization layer and connected to the plurality of light-emitting elements, respectively; and a passivation layer disposed between the plurality of reflectors and the adhesive layer, wherein the step structure may be formed of the passivation layer.

[0139] According to another feature of the present disclosure, a concave-convex pattern may be formed on a lower surface of each of the plurality of light emitting elements.

[0140] According to another feature of the present specification, a gap may be formed between the adhesive layer and the concave-convex pattern, and the height ratio of the gap to the height of the concave-convex pattern may be 5 or less.

[0141] According to another feature of the present disclosure, the bottom surfaces of the plurality of light emitting devices may all be in contact with the adhesive layer in the first region so that no gaps are formed between the adhesive layer and the uneven pattern.

[0142] According to another feature of the present specification, each of the plurality of light-emitting elements includes a first semiconductor layer on the adhesive layer, a second semiconductor layer disposed on the first semiconductor layer, a light-emitting layer disposed between the first semiconductor layer and the second semiconductor layer, a first electrode disposed on the first semiconductor layer and spaced apart from the light-emitting layer, and a second electrode disposed on the second semiconductor layer, and the lower surface of the first semiconductor layer may be in direct contact with a first region of the adhesive layer.

[0143] Although the embodiments of the present specification have been described in more detail above with reference to the accompanying drawings, the present specification is not necessarily limited to these embodiments and may be variously modified within the scope of the technical concept of the present specification. Therefore, the embodiments disclosed in the present specification are intended to illustrate, not limit, the technical concept of the present specification, and the scope of the technical concept of the present specification is not limited by these embodiments. Therefore, the embodiments described above should be understood to be illustrative in all respects and not limiting. The scope of protection of the present specification should be interpreted by the scope of the claims, and all technical concepts within the scope equivalent thereto should be interpreted as being included in the scope of the present specification. [Explanation of symbols]

[0144] 100 display device 110 Substrate 120 Adhesive layer

Claims

1. a substrate including a plurality of sub-pixels; a thin film transistor disposed on the substrate; an adhesive layer disposed on the thin film transistor, the adhesive layer including a first region and a second region having a higher tan δ value than the first region; a plurality of light-emitting elements disposed in the first region of the adhesive layer corresponding to the plurality of sub-pixels; The tan δ value is N / mm ２ The display device is a dimensionless value obtained by dividing the indentation hardness value calculated in units by the indentation modulus value calculated in units of MPa.

2. the tan δ value of the first region is 0.01 or less, 2. The display device according to claim 1, wherein the tan δ value of the second region is 0.08 to 0.

2.

3. The display device of claim 1 , wherein the second region has a higher degree of hardness than the first region.

4. The display device according to claim 1 , wherein the adhesive layer includes a binder resin, a photosensitive agent, a first functional monomer, and a second functional monomer, and is capable of forming a surface having a higher tan δ value than the first functional monomer.

5. The first functional monomer may be diurethane dimethacrylate, polyethylene glycol dimethacrylate, bisphenol A (EO) 10 diacrylate, bisphenol A (EO) 30 diacrylate, tricyclodecane dimethanol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 300 diacrylate, polyethylene glycol 400 diacrylate, polyethylene glycol 600 diacrylate, polyethylene glycol 1000 diacrylate, tris(2-hydroxyethyl)isocyanurate diacrylate, or 5. The display device of claim 4, comprising one or more selected from the group consisting of acrylate, butylated hydroxyanisole, 2,6-di-tert-butyl-4-hydroxymethylphenol, butylated hydroxytoluene, propyl gallate, lauryl gallate, octyl gallate, 2,4,5-trihydroxybutyrophenone, tert-butylhydroquinone, 3-aminophenol, 4-aminophenol, 4-methoxyphenol, 2,3,5-trimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, poly(4-vinylphenol), and 4-bromophenol.

6. 5. The display device of claim 4, wherein the second functional monomer comprises at least one selected from the group consisting of 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,3-butylene glycol diacrylate, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, propylene glycol dimethacrylate, pentaerythritol tetraacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, pentaerythritol hexaacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, dipentaerythritol diacrylate, sorbitol triacrylate, bisphenol A diacrylate derivatives, trimethylpropane triacrylate, and methacrylates thereof.

7. 5. The display device of claim 4, wherein a total content of the first functional monomer and the second functional monomer is 10 to 70 parts by weight based on 100 parts by weight of the binder resin.

8. The display device according to claim 1 , wherein an upper surface of the first region protrudes from an upper surface of the second region toward the plurality of light-emitting elements.

9. The display device of claim 8 , further comprising a step structure disposed under the adhesive layer and including protrusions protruding toward the plurality of light emitting devices in correspondence with the first region.

10. a planarization layer disposed on the thin film transistor; a plurality of reflectors disposed on the planarization layer and connected to the plurality of light emitting devices, respectively; a passivation layer disposed between the plurality of reflectors and the adhesive layer; The display device of claim 9 , wherein the step structure is disposed between the plurality of reflectors and the passivation layer, or between the passivation layer and the adhesive layer.

11. a planarization layer disposed on the thin film transistor; a plurality of reflectors disposed on the planarization layer and connected to the plurality of light emitting devices, respectively; a passivation layer disposed between the plurality of reflectors and the adhesive layer; The display device of claim 9 , wherein the step structure is formed by the passivation layer.

12. The display device according to claim 1 , wherein a concave-convex pattern is formed on the bottom surface of each of the plurality of light-emitting elements.

13. A gap is formed between the adhesive layer and the concave-convex pattern, The display device according to claim 12 , wherein the ratio of the height of the void to the height of the concave-convex pattern is 5 or less.

14. The display device of claim 12 , wherein the bottom surfaces of the plurality of light emitting elements are in contact with the adhesive layer in the first region so that no gap is formed between the adhesive layer and the uneven pattern.

15. Each of the plurality of light-emitting elements is a first semiconductor layer on the adhesive layer; a second semiconductor layer disposed on the first semiconductor layer; a light emitting layer disposed between the first semiconductor layer and the second semiconductor layer; a first electrode disposed on the first semiconductor layer and spaced apart from the light emitting layer; a second electrode disposed on the second semiconductor layer; The display device of claim 12 , wherein the lower surface of the first semiconductor layer is in direct contact with the first region of the adhesive layer.

16. 2. The display device according to claim 1, wherein the difference between the tan δ value of the second region and the tan δ value of the first region is 0.05 to 0.

2.

17. a display device; a substrate including a plurality of sub-pixels; a thin film transistor disposed on the substrate; an adhesion layer including one or more sub-patterns and disposed on the thin film transistor; a plurality of light-emitting elements disposed on the adhesive layer corresponding to the plurality of sub-pixels; the plurality of sub-patterns of the adhesive layer have a tan δ value that is lower than an overall average tan δ value of the adhesive layer, and the plurality of light-emitting elements are aligned with the sub-patterns of the adhesive layer; The tan δ value is N / mm ２ 4. A display device according to claim 1, wherein the indentation hardness is a dimensionless value obtained by dividing an indentation hardness value calculated in units by an indentation elastic modulus value calculated in units of MPa.

18. 20. The display device of claim 17, wherein the plurality of sub-patterns of the adhesive layer have tan δ values ​​that are at least 0.05 lower than the tan δ values ​​of other areas of the adhesive layer.

19. 18. The display device of claim 17, wherein the adhesive layer comprises a binder resin, a photosensitive agent, a first functional monomer, and a second functional monomer, the second functional monomer being capable of forming a surface having a higher tan δ value than the first functional monomer, and the total content of functional monomers including the first functional monomer being capable of forming a surface having a higher tan δ value than the first functional monomer.

20. 20. The display device according to claim 19, wherein a content ratio of the first functional monomer to the second functional monomer is 3:1 to 1:1.

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