Indication device

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] This specification relates to a display device and a method for manufacturing the same, and more particularly, to a display device in which adhesion failure of a light emitting element (Light Emitting Diode) is improved.

Background Art

[0002] Display devices used in computer monitors, TVs, mobile phones, etc. include organic light emitting display devices (Organic Light Emitting Display; OLED) that emit light by themselves, and liquid crystal display devices (Liquid Crystal Display; LCD) that require a separate light source.

[0003] The application range of display devices is diverse not only in computer monitors and TVs but also in personal mobile devices, and research is underway on display devices that have a reduced volume and weight while having a large display area.

[0004] In recent years, display devices including light emitting elements (Light Emitting Diode) have attracted attention as next-generation display devices. Since the light emitting element is made of an inorganic substance that is not an organic substance, it has excellent reliability and a longer lifespan compared to liquid crystal display devices and organic light emitting display devices. In addition, the light emitting element not only has a fast lighting speed, but also has excellent luminous efficiency, strong impact resistance, excellent stability, and can display high-brightness images.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem to be solved by this specification is to prevent transfer failure that occurs in the process of transferring a light emitting element to a display panel.

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

[0007] Another problem that this specification seeks to solve is to provide a display device that offers excellent transfer yield and allows the stamp to be used multiple times.

[0008] The problems described herein are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0009] A display device according to one embodiment of this specification includes a substrate containing 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 tanδ value than the first region, and a light-emitting element disposed in the first region of the adhesive layer corresponding to the plurality of subpixels, wherein the tanδ value is N / mm 2 This is a dimensionless value obtained by dividing the press-fit hardness value calculated in units by the press-fit modulus value calculated in MPa units.

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

[0011] This specification can eliminate the defect in which light-emitting elements are transferred to undesired areas during the transfer process of light-emitting elements.

[0012] This specification can reduce transfer errors of light-emitting elements and improve process yield.

[0013] This specification significantly reduces the problem of reduced adhesion between the light-emitting element and the adhesive layer, or the visibility of the boundary of the light-emitting element, due to voids caused by the uneven pattern formed on the underside of the light-emitting element.

[0014] The effects described herein are not limited to those exemplified above, and a wider variety of effects are included within this specification. [Brief explanation of the drawing]

[0015] [Figure 1] It is a schematic configuration diagram of a display device according to an embodiment of the present specification. [Figure 2] It is a cross-sectional view of a display device according to an embodiment of the present specification. [Figure 3] It is a schematic cross-sectional view for explaining a display device according to another embodiment of the present specification. [Figure 4] It is a flowchart of steps for explaining a manufacturing method of a display device according to an embodiment of the present specification. [Figure 5a] It is a cross-sectional view of steps for explaining a manufacturing method of a display device according to an embodiment. [Figure 5b] It is a cross-sectional view of steps for explaining a manufacturing method of a display device according to an embodiment. [Figure 5c] It is a cross-sectional view of steps for explaining a manufacturing method of a display device according to an embodiment. [Figure 5d] It is a cross-sectional view of steps for explaining a manufacturing method of a display device according to an embodiment. [Figure 6a] Images of cross-sections between the adhesive layer and the light-emitting element taken in Comparative Example 1 and Example 1. [Figure 6b] Images of cross-sections between the adhesive layer and the light-emitting element taken in Comparative Example 1 and Example 1. [Figure 7a] Images evaluating transfer defects in Comparative Example 1 and Example 1. [Figure 7b] Images evaluating transfer defects in Comparative Example 1 and Example 1.

Mode for Carrying Out the Invention

[0016] The advantages and features of this specification and the methods for achieving them will become clear by referring to the embodiments described in detail below together with the accompanying drawings. However, this specification is not limited to the embodiments disclosed below, but is configured in various different forms. Merely, these embodiments are provided so that the disclosure of this specification is complete and to fully inform those with ordinary knowledge in the technical field to which this specification pertains of the scope of this specification.

[0017] The shapes, areas, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of this specification are exemplary, so this specification is not limited to the matters illustrated. Throughout the specification, the same reference numerals refer to the same components. Also, when explaining this specification, if it is determined that a detailed description of related known technologies may muddy the gist of this specification, the detailed description thereof will be omitted. When terms such as "including", "having", "being made" are used in this specification, other parts can be added as long as "only" is not used. When a component is expressed in the singular, it includes the case of including a plurality unless otherwise explicitly stated.

[0018] When interpreting a component, it is interpreted as including an error range even without a separate explicit description.

[0019] When it is an explanation of a positional relationship, for example, when the positional relationship between two parts is described such as "on", "above", "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 both the case where there is another layer or another element immediately above the other element or intervening between them.

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

[0022] Throughout the specification, the same reference numeral refers to the same component.

[0023] The area and thickness of each component shown in the drawings are provided for illustrative purposes only, and this specification is not necessarily limited to the area and thickness of the components shown.

[0024] The features of each of the various embodiments described herein can be combined or linked together, either partially or entirely, allowing for a variety of technically diverse interoperability and drive, and each embodiment may be implemented independently of the others or together in relation to one another.

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

[0026] Figure 1 is a schematic diagram of a display device according to one embodiment of this specification. In Figure 1, for the sake of explanation, only the display panel PN, gate drive unit GD, data drive unit DD, and timing controller TC are shown among the various components of the display device 100.

[0027] Referring to Figure 1, the display device 100 includes a display panel PN containing a plurality of subpixels SP, a gate drive unit GD and a data drive unit DD that supply various signals to the display panel PN, and a timing controller TC that controls the gate drive unit GD and the data drive unit DD.

[0028] The gate drive unit GD supplies multiple scan signals to multiple scan wirings SL based on multiple gate control signals provided by the timing controller TC. In Figure 1, one gate drive unit GD is shown spaced apart on one side of the display panel PN, but the number and arrangement of gate drive units GD are not limited to this.

[0029] The data drive unit DD converts video data input from the timing controller TC into data voltage using a reference gamma voltage, based on multiple data control signals provided by the timing controller TC. The data drive unit DD can then supply the converted data voltage to multiple data wirings DL.

[0030] The timing controller TC aligns the video data input from an external source and supplies it to the data drive unit DD. The timing controller TC can generate gate control signals and data control signals using synchronization signals input from an external source, such as a dot clock signal, a data enable signal, and horizontal / vertical synchronization signals. The timing controller TC can then control the gate drive unit GD and the data drive unit DD by supplying the generated gate control signals and data control signals to the gate drive unit GD and the data drive unit DD, respectively.

[0031] The display panel PN is configured to display images to the user and includes multiple sub-pixels SP. Multiple scan lines SL and multiple data lines DL intersect within the display panel PN, and each of the multiple sub-pixels SP is connected to the scan lines SL and data lines DL. In addition, although not shown in the drawing, each of the multiple sub-pixels SP may be connected to high-potential power lines, low-potential power lines, reference lines, etc.

[0032] The display panel PN may define a display area AA and a non-display area NA that surrounds the display area AA.

[0033] Display area AA is the area where the image is displayed on the display device 100. Display area AA may contain multiple subpixels SP that constitute multiple pixels and circuits for driving the multiple subpixels SP. Multiple subpixels SP are the smallest units that constitute display area AA, and n subpixels SP can form one pixel. Each of the multiple subpixels SP may contain a light-emitting element and a thin-film transistor or the like for driving the light-emitting element. Multiple light-emitting elements may be defined differently depending on the type of display panel PN. For example, if the display panel PN is an inorganic light-emitting display panel, the light-emitting elements may be light-emitting elements (light-emitting diodes) or micro light-emitting elements (micro light-emitting diodes).

[0034] The display area AA is arranged with multiple wirings that transmit various signals to multiple sub-pixels SP. For example, the multiple wirings may include multiple data wirings DL that supply data voltage to each of the multiple sub-pixels SP, and multiple scan wirings SL that supply scan signals to each of the multiple sub-pixels SP. Multiple scan wirings SL may extend from the display area AA in one direction and be connected to the multiple sub-pixels SP, and multiple data wirings DL may extend from the display area AA in directions other than one direction and be connected to the multiple sub-pixels SP. In addition, the display area AA may, but is not limited to, low-potential power supply wiring, high-potential power supply wiring, etc.

[0035] The non-display area NA is an area where the image is not displayed, and can be defined as an area extending from the display area AA. Link wiring and pad electrodes for transmitting signals to the subpixels SP of the display area AA, as well as drive ICs such as gate driver ICs and data driver ICs, may be placed in the non-display area NA.

[0036] However, the non-display area NA may be located on the back of the display panel PN, i.e., on the side without subpixels SP, or may be omitted, and is not limited to what is shown in the drawing.

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

[0038] If the gate drive unit GD is implemented using the GIP method, and the data drive unit DD and timing controller TC transmit signals to the display panel PN through the pad electrodes of the non-display area NA, then the area of ​​the non-display area NA required for arranging the gate drive unit GD and pad electrodes must be above a certain level, which may increase the bezel size.

[0039] In contrast, when the gate drive unit GD is implemented inside the display area AA using the GIA method, and side wiring is formed to connect the signal wiring on the front of the display panel PN to the pad electrodes on the back of the display panel PN, and a flexible film and printed circuit board are bonded to the back of the display panel PN, the non-display area NA on the front of the display panel PN can be minimized. That is, when the gate drive unit GD, data drive unit DD, and timing controller TC are connected to the display panel PN in the manner described above, it may be possible to realize a zero-bezel system where there is virtually no bezel.

[0040] Figure 2 is a cross-sectional view of a display device according to one embodiment of this specification.

[0041] The substrate 110 is a substrate that supports components placed on top of the display device 100, and may be an insulating substrate. Multiple subpixels SP are formed on the substrate 110 so that an image can be displayed. For example, the substrate 110 may be made of glass or resin. The substrate 110 may also contain polymers or plastics. 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 arranged in each of the multiple sub-pixels SP on the substrate 110. The pixel circuit may include multiple thin-film transistors and multiple capacitors. In Figure 2, for the sake of explanation, only the driving transistor DT, the first capacitor C1, and the second capacitor C2 of the pixel circuit are shown, but the pixel circuit may further include, and is not limited to, switching transistors, sensing transistors, light emission control transistors, etc.

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

[0044] A buffer layer 111 is placed 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 may, but is not limited to, a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx). However, the buffer layer 111 may, but is not limited to, be omitted depending on the type of substrate 110 or the type of thin-film transistor.

[0045] An active layer ACT and a drive transistor DT including a gate electrode GE, source electrode SE, and drain electrode DE are arranged on the buffer layer 111.

[0046] First, the active layer ACT of the drive transistor DT is placed on the buffer layer 111. The active layer ACT may, but is not limited to, a semiconductor material such as oxide semiconductor, amorphous silicon, or polysilicon. In addition, although not shown in the drawings, other transistors such as switching transistors, sensing transistors, and light emission control transistors may be placed, and the active layers of such transistors may, but are not limited to, a semiconductor material such as oxide semiconductor, amorphous silicon, or polysilicon. Furthermore, the active layers of transistors included in the pixel circuit, such as the drive transistor DT, switching transistors, sensing transistors, and light emission control transistors, may be made of the same material or different materials.

[0047] A gate insulating layer 112 is placed 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, but is not limited to, a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx).

[0048] A gate electrode GE is placed on the gate insulating layer 112. The gate electrode GE may, but is not limited to, a conductive material such as 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 arranged on the gate electrode GE. Contact holes are formed in the first interlayer insulating layer 113 and the second interlayer insulating layer 114 for the source electrode SE and the drain electrode DE to connect 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 structure and may, but are not limited to, a single or multiple layer of silicon oxide (SiOx) or silicon nitride (SiNx).

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

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

[0052] First, the first-first capacitor electrode C1a is placed on the gate insulating layer 112. The first-first capacitor electrode C1a may be integrated with the gate electrode GE of the drive transistor DT.

[0053] The first-to-second capacitor electrode C1b is placed on the first interlayer insulating layer 113. The first-to-second capacitor electrode C1b is positioned so as to overlap with the first-to-first capacitor electrode C1a, with the first interlayer insulating layer 113 in between.

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

[0055] Next, a second capacitor C2 is placed on the substrate 110. The second capacitor C2 includes a second-first capacitor electrode C2a, a second-second capacitor electrode C2b, and a second-third capacitor electrode C2c. The second capacitor C2 includes a second-first capacitor electrode C2a which is the lower capacitor electrode, a second-second capacitor electrode C2b which is the intermediate capacitor electrode, and a second-third capacitor electrode C2c which is the upper capacitor electrode.

[0056] A second-first capacitor electrode C2a is placed on the substrate 110. The second-first capacitor electrode C2a is placed in the same layer as the light-shielding layer BSM and may be made of the same material.

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

[0058] The second and third capacitor electrodes C2c are arranged on the first interlayer insulating layer 113. The second and third capacitor electrodes C2c may consist of a first layer C2c1 and a second layer C2c2. The first layer C2c1 of the second and third capacitor electrodes C2c may be the same layer and made of the same material as the first and second capacitor electrodes C1b. The first layer C2c1 may be arranged to overlap with the second-first capacitor electrode C2a and the second-second capacitor electrode C2b, with the first interlayer insulating layer 113 in between.

[0059] The second layer C2c2 of the second-to-third capacitor electrode C2c is located on the second interlayer insulating layer 114. The second layer C2c2 is the portion extending from the source electrode SE of the drive transistor DT and can be connected to the first layer C2c1 through the contact holes of 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, allowing the light-emitting element 130 to emit light of higher brightness.

[0061] A first passivation layer 115a is placed on a drive transistor DT, a first capacitor C1, and a second capacitor C2. The first passivation layer 115a is an insulating layer for protecting the underlying structure and may, but is not limited to, an inorganic material such as silicon oxide (SiOx) or silicon nitride (SiNx).

[0062] A first planarization layer 116a is placed on a first passivation layer 115a. The first planarization layer 116a can planarize the area above the pixel circuit, including the drive transistor DT. The first planarization layer 116a may be a single layer or a multi-layer structure and may, for example, be made of benzocyclobutene or an acrylic-based organic material, but is not limited thereto.

[0063] Multiple reflector RFs are arranged on the first planarization layer 116a. The reflector RFs are configured to reflect light emitted by multiple light-emitting elements 130 to the upper part of the substrate 110, and can be shaped to correspond to each of the multiple sub-pixels SP. One reflector RF may be arranged to cover most of the area of ​​one sub-pixel SP. The reflector RFs can be electrically connected to the source electrode SE of the drive transistor DT and the second capacitor C2 through the first contact hole CH1 of the first planarization layer 116a and the first passivation layer 115a. Thus, the reflector RFs can electrically connect the drive transistor DT and the first electrode 134 of the light-emitting element 130. The reflector RFs can reflect light emitted by the light-emitting element 130 and can also be used as electrodes to electrically connect the light-emitting element 130 and the pixel circuit. Therefore, the reflector RFs can include various conductive layers considering light reflection efficiency and resistance. For example, a reflector RF can use both an opaque conductive layer such as silver (Ag), aluminum (Al), molybdenum (Mo), titanium (Ti), or alloys thereof, and a transparent conductive layer such as ITO (Indium Tin Oxide), but the structure of the reflector RF is not limited to this.

[0064] A second passivation layer 115b is placed on multiple reflector RFs. The second passivation layer 115b is an insulating layer for protecting the underlying structure of the second passivation layer 115b and may consist of a single or multiple layer of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

[0065] An adhesive layer 120 is placed on the second passivation layer 115b. The adhesive layer 120 is formed on the front surface of the substrate 110 and can fix the light-emitting element 130 that is placed on the adhesive layer 120. The adhesive layer 120 can also insulate the reflector RF, which is made of a metallic material, from the light-emitting element 130. The adhesive layer 120 may be placed so as to overlap with the reflector RF that is placed on each of the multiple sub-pixels SP. The adhesive layer 120 may be separated for each of the multiple sub-pixels SP so as to overlap with the reflector RF, but it may also be placed on the entire second passivation layer 115b. In addition, the adhesive layer 120 may be formed on the front surface of the substrate 110, excluding the multiple pad regions where the first pad electrodes are placed.

[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 the region that adheres to the light-emitting element 130 and has sufficient adhesive strength to adhere to the light-emitting element 130. The second region 122 is the region 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 tanδ value, and the second region 122 has a high tanδ value. The tanδ value indicates the balance between viscosity and elasticity of the adhesive layer 120. More specifically, the tanδ value is related to the Indentation Hardness (HIT, N / mm²). 2 ) / Indentation Modulus (EIT, MPa) can be defined as the tanδ value, which is N / mm². 2The press-fit hardness (HIT) is a dimensionless value obtained by dividing the press-fit hardness value calculated in units by the press-fit modulus value calculated in MPa units. In this case, press-fit hardness (HIT) can represent the press-fit hardness at a depth of tens to hundreds of nanometers from the surface of the adhesive layer 120. The press-fit hardness (HIT) may be related to the plasticity of the adhesive layer 120 among its elasticity and plasticity properties. The press-fit modulus (EIT) can represent the press-fit modulus at a depth of tens to hundreds of nanometers from the surface of the adhesive layer 120. The press-fit modulus (EIT) may be related to the elasticity of the adhesive layer 120 among its elasticity and plasticity properties. On the other hand, press-fit hardness (HIT) and press-fit modulus (EIT) can be measured through a nanoindenter according to the ISO 14577 standard.

[0068] Specifically, the tanδ value of the first region 121 may be 0.01 or less, 0.008 or less, or 0.001 to 0.008, and the tanδ value of the second region 122 may be 0.05 or more, 0.1 or more, or 0.08 to 0.2. When the tanδ 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 more rigid surface. This prevents the light-emitting element 130 from being transferred to an undesirable region, namely the second region 122.

[0069] The adhesive layer 120 may consist of a photocurable adhesive material that can be cured by ultraviolet light. For example, the adhesive layer 120 may consist of an acrylic series 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 photosensitive agent. For example, the binder resin may be an acrylic resin. The photosensitive agent may be one or more selected from oxime-based and benzophenone-based photoinitiators. On the other hand, the functional monomer controls the tackiness of the adhesive layer 120 and adjusts the tanδ value. Specifically, the functional monomer includes a low tanδ monomer (A, first functional monomer) and a high tanδ monomer (B, second functional monomer).

[0071] Specifically, the low tanδ monomer (A) is a low molecular weight monomer with high fluidity, which can improve the adhesion of the first region 121 and improve the transfer process yield of the light-emitting element 130. For example, the low tanδ monomer (A) is diurethane dimethacrylate, polyethylene glycol dimethacrylate, bisphenol A(EO)10 diacrylate, bisphenol A(EO)30 diacrylate, tricyclodecanedimethanol 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 di It may contain, but is not limited to, one or more selected from the group consisting of acrylate, buttyrate hydroxyanisole, 2,6-di-tert-butyl-4-hydroxymethylphenol, butyrate 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 tanδ monomer (B) improves the tanδ value when the adhesive layer 120 is irradiated with ultraviolet light, making the film surface properties more 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 tanδ 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 low tanδ monomer (A) to high tanδ monomer (B) may be 3:1 to 1:1. When the content of low tanδ monomer (A) and high tanδ monomer (B) satisfies the above range, the adhesive strength of the first region 121 is secured while the adhesive strength of the second region 122 is reduced, potentially improving the plastic properties. This makes it possible to improve the yield of the light-emitting element 130 being transferred to the first region 121 during the transfer process of the light-emitting element 130 in the future, and to prevent the light-emitting element 130 from being transferred to the second region 122.

[0074] On the other hand, the combined content of the functional monomer, which includes both low-tanδ monomer (A) and high-tanδ 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 monomer falls outside the above 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 ultraviolet light. For example, when ultraviolet light is irradiated to a portion of the adhesive layer 120, the tanδ value of the irradiated region is improved by the high tanδ monomer (B), improving the properties of the plasticity film surface. As a result, the irradiated region will form the second region 122, where the light-emitting element 130 will not be transferred. On the other hand, the region not irradiated with ultraviolet light will form the first region 121. The first region 121 has a low tanδ value due to the low tanδ monomer (A), resulting in improved adhesive strength. The specific method for forming the first region 121 and the second region 122 of the adhesive layer 120 will be described later.

[0076] On the other hand, 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 tanδ monomer (A) as a functional monomer, and the second region 122 may contain only a high tanδ monomer (B) as a functional monomer. That is, the first region 121 may be formed from a first composition containing a binder resin, a low tanδ monomer (A), and a photosensitive agent, and the second region 122 may be formed from a second composition containing a binder resin, a high tanδ monomer (B), and a photosensitive agent.

[0077] The widths of the first region 121 and the second region 122 of the adhesive layer 120 can be determined considering the size of the light-emitting element 130 and the process margin. For example, the widths of the first region 121 and the second region 122 may be 20 μm to 200 μm or 50 μm to 150 μm, but are not limited thereto. On the other hand, the thickness of the first region 121 and the second region 122 of the adhesive layer 120 may be 2 μm to 5 μm, but are not limited thereto. Furthermore, as will be described later, the thickness of the first region 121 on which the light-emitting element 130 is placed may be thicker than that of the second region 122.

[0078] The upper surface of the first region 121 of the adhesive layer 120 may have a shape that protrudes toward the light-emitting element 130 from the upper surface of the second region 122. Having a structure in which the first region 121 protrudes toward the upper part of the second region 122 allows the light-emitting element 130 to be transferred with an even higher yield during the process of transferring and pressurizing the light-emitting element 130 to the display panel.

[0079] On the other hand, other embodiments of this specification may further include a stepped structure for which the first region 121 of the adhesive layer 120 has a protruding shape.

[0080] Figure 3 is a schematic cross-sectional view illustrating a display device according to another embodiment of this specification. Referring to Figure 3, a stepped structure 160 is positioned below the adhesive layer 120, including a projection that protrudes toward the light-emitting element 130. The stepped structure 160 is positioned in contact with the adhesive layer 120, and can form a structure in which the upper surface of the first region 121 protrudes above the upper surface of the second region 122 for the projection corresponding to the first region 121. The light-emitting element 130 can be transferred to the first region 121 of the adhesive layer 120 with a higher yield through the stepped structure 160. The stepped structure 160 may be located on the reflector RF and beneath the light-emitting element 130. The stepped structure 160 can also be formed using the second passivation layer 115b. Alternatively, the stepped structure 160 may be formed between the second passivation layer 115b and the adhesive layer 120, or located between the second passivation layer 115b and the reflector RF.

[0081] Multiple light-emitting elements 130 are arranged on each of the multiple subpixels SP on the adhesive layer 120. The light-emitting elements 130 are elements that emit light in response to an electric current, and can include red light-emitting elements that emit red light, green light-emitting elements that emit green light, and blue light-emitting elements, and a variety of hues of light, including white, can be realized by combinations of these. For example, the light-emitting elements 130 may be LEDs (Light Emitting Diodes) or micro-LEDs, but are not limited to these.

[0082] Each light-emitting element can be driven individually by being connected to the respective drive transistor DT of each subpixel.

[0083] The multiple 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 placed on the adhesive layer 120, and a second semiconductor layer 133 is placed on the first semiconductor layer 131. The first semiconductor layer 131 and the second semiconductor layer 133 may be layers formed by doping specific materials with n-type and p-type impurities. For example, the first semiconductor layer 131 and the second semiconductor layer 133 may each be layers doped with n-type and p-type impurities in materials such as gallium nitride (GaN), indium aluminum phosphide (InAlP), gallium arsenide (GaAs), etc. 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 to these.

[0085] Multiple uneven patterns may be formed on the underside of the first semiconductor layer 131 that is in contact with the adhesive layer 120. These uneven patterns may be formed on the underside of the first semiconductor layer 131 during the manufacturing process of the light-emitting element 130 and during the primary transfer process of the light-emitting element 130 to the donor substrate.

[0086] A light-emitting layer 132 is disposed between a first semiconductor layer 131 and a 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 can be 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] A first electrode 134 is placed on the first semiconductor layer 131. The first electrode 134 is an electrode for electrically connecting the drive transistor DT and the first semiconductor layer 131. In this case, the first semiconductor layer 131 is a semiconductor layer doped with n-type impurities, and the first electrode 134 may be a cathode. The first electrode 134 may be placed on the 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, such as a transparent conductive material like ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), or an opaque conductive material like titanium (Ti), gold (Au), silver (Ag), copper (Cu), or alloys thereof, but is not limited thereto.

[0088] A second electrode 135 is placed on the second semiconductor layer 133. The second electrode 135 may be placed on the upper surface of the second semiconductor layer 133. The second electrode 135 is an electrode for electrically connecting the high-potential power supply wiring and the second semiconductor layer 133. In this case, the second semiconductor layer 133 is 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, such as a transparent conductive material like ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), or an opaque conductive material like titanium (Ti), gold (Au), silver (Ag), copper (Cu), or alloys thereof, but is not limited thereto.

[0089] Next, a sealing film 136 is placed surrounding 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 are formed in the sealing film 136 to expose the first electrode 134 and the second electrode 135, 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] On the other hand, a portion of the side surface of the first semiconductor layer 131 may be exposed from the sealing film 136. The light-emitting element 130 manufactured on the wafer can be separated from the wafer and transferred to the display panel PN. However, a portion of the sealing film 136 may be peeled off during the process of separating the light-emitting element 130 from the wafer. For example, a portion of the sealing film 136 adjacent to the lower edge of the first semiconductor layer 131 of the light-emitting element 130 may be peeled off during the separation process of the light-emitting element 130 from the wafer, 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 element 130 is exposed from the sealing 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 surface of the first semiconductor layer 131, so short-circuit defects can be reduced.

[0091] Next, a second planarization layer 116b and a third planarization layer 116c are placed on the adhesive layer 120 and the light-emitting element 130. The second planarization layer 116b can be superimposed on a portion of the side surfaces of the multiple light-emitting elements 130 to fix and protect the multiple light-emitting elements 130. The third planarization layer 116c is formed to cover the second planarization layer 116b and the upper portion of the light-emitting elements 130, and contact holes may be formed that expose the first electrode 134 and the second electrode 135 of the light-emitting elements 130. The first electrode 134 and the second electrode 135 of the light-emitting elements 130 are exposed from the third planarization layer 116c, and the third planarization layer 116c can be partially placed 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 single-layer or multi-layer and may, for example, be made of photoresist or acrylic-based organic material, but are not limited thereto.

[0092] On the other hand, the third flattening layer 116c may cover only the light-emitting element 130 and the region adjacent to the light-emitting element 130. The third flattening layer 116c may be arranged in an island configuration in the region of the subpixel SP surrounded by the bank 140. Thus, the bank 140 may be arranged on a part of the upper surface of the second flattening layer 116b, and the third flattening layer 116c may be arranged on the other part of the upper surface of the second flattening layer 116b.

[0093] A first connecting electrode CE1 and a second connecting electrode CE2 are arranged on the third planarization layer 116c. The first connecting electrode CE1 is an electrode that electrically connects the second electrode 135 of the light-emitting element 130 to the high-potential power supply wiring. The first connecting electrode CE1 can 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 is an electrode that electrically connects the first electrode 134 of the light-emitting element 130 to the drive transistor DT. The second connecting electrode CE2 can be connected to the reflector RF of each of the multiple subpixels 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, since the reflector RF is also connected to the source electrode SE of the drive transistor DT, the source electrode SE of the drive transistor DT and the first electrode 134 of the light-emitting element 130 can be electrically connected to each other.

[0095] On the other hand, although the drawing shows the first electrode 134, the second connecting electrode CE2, and the reflector RF being electrically connected to the source electrode SE of the drive transistor DT, the first electrode 134, the second connecting electrode CE2, and the reflector RF may also be connected to the drain electrode DE of the drive transistor DT, and are not limited to this configuration.

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

[0097] A protective layer 117 is placed 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 beneath it. The protective layer 117 may consist of a single layer or multiple layers and may, for example, be made of benzocyclobutene, a translucent epoxy, a photoresist, or an acrylic organic material, but is not limited thereto.

[0098] An optical film 150 is placed on the protective layer 117. The optical film 150 may be a functional film that protects the display device 100 while achieving higher image quality. For example, the optical film 150 may include, but is not limited to, a shatterproof film, an anti-glare film, an anti-reflective film, a low-reflecting film, an OLED Transmittance Controllable Film, or a polarizing plate.

[0099] The following describes a method for manufacturing a display device according to one embodiment of this specification.

[0100] Figure 4 is a flowchart illustrating the process for manufacturing a display device according to one embodiment of this specification. Figures 5a and 5d are cross-sectional views illustrating the process for manufacturing a display device according to one embodiment.

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

[0102] First, referring to Figure 5a, an adhesive composition is coated onto the display panel to form an adhesive coating layer 120' (S110). At this time, the adhesive composition contains a photocurable adhesive substance and, as described above, contains a low tanδ monomer (A) and a high tanδ monomer (B). The method for coating the adhesive composition can be a general adhesive coating method such as spin coating or printing, but is not limited to this.

[0103] Referring to Figure 5b, the adhesive coating layer 120' is irradiated with ultraviolet light using a mask MS to form an adhesive layer including the first and second regions (S120). The adhesive strength and tanδ value can be adjusted by irradiating the adhesive coating layer 120' corresponding to the second region 122 where the light-emitting element 130 is not placed with ultraviolet light.

[0104] More specifically, referring to Figure 5c, in Figure 5a, when the compound constituting the adhesive coating layer 120' is irradiated with ultraviolet light, the adhesive strength decreases and the tanδ value improves in the region irradiated with ultraviolet light through the mask MS, thereby forming a second region 122 where the light-emitting element 130 has not been transferred. Therefore, an adhesive layer 120 including the first region 121 and the second region 122 can be formed through the step of irradiating with ultraviolet light using a mask MS.

[0105] Referring to Figure 5d, the donor substrate 200 on which the multiple light-emitting elements 130 are arranged is aligned with the display panel (S130). First, the donor substrate 200 on which the multiple 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 a structure for supporting the various components included in the donor substrate 200 and may be made of a material that is at least rigid to the resin layer 230 in order to minimize the warping of the resin layer 230. The adhesive layer 220 adheres the resin layer 230 and the base layer 210. For example, the adhesive layer 220 may be made of OCA (Optical Clear Adhesive), PSA (Pressure Sensitive Adhesive), etc., but is not limited thereto. The adhesive layer 220 may be omitted depending on the design, but is not limited thereto. The resin layer 230 includes a region on which the multiple light-emitting elements 130 formed on the wafer are primary transferred. The resin layer 230 may consist of a viscoelastic polymer resin.

[0106] A donor substrate 200 on which multiple light-emitting elements 130 are arranged, and a display panel are placed into the process equipment, and the donor substrate 200 and the display panel placed in the process equipment are aligned so that they face each other. At this time, the display panel is a display panel on which the circuit for driving the multiple light-emitting elements 130, such as a drive transistor and multiple wirings, has been formed. The display panel is also a display panel on which the adhesive layer 120, including a first region 121 and a second region 122, has been formed on the circuit. Multiple alignment keys are formed on the display panel, which can be aligned with multiple alignment marks formed on the donor substrate. Through this, at least some of the multiple light-emitting elements 130 on the donor substrate 200 are aligned so that they correspond to the first region 121 of the adhesive layer 120 formed on the upper surface of the display panel.

[0107] Multiple light-emitting elements 130 are bonded to the donor substrate 200 and the display panel so that they correspond to the first region 121 (S140). The display panel and the donor substrate 200 are bonded together while maintaining the state in which the alignment of the display panel and the donor substrate 200 is completed.

[0108] Subsequently, multiple light-emitting elements 130 from the donor substrate 200 are transferred to the display panel (S150). With the display panel and the donor substrate 200 bonded together facing each other, the laser can be selectively irradiated only the light-emitting elements 130 to be transferred to the display panel. The light-emitting elements 130 that have been irradiated with the laser can be transferred to the first region 121 of the adhesive layer 120 formed on the upper surface of the display panel after being detached from the donor substrate 200.

[0109] Subsequently, the display panel and the donor substrate 200 are detached, and the donor substrate 200 with the light-emitting element 130 transferred onto it is ejected using process equipment (S160).

[0110] Generally, display devices containing light-emitting elements such as LEDs are manufactured through a process of transferring or stamping the display elements from a donor substrate onto a display panel on which driving elements and adhesive layers are formed. However, in the case of small light-emitting elements such as micro-LEDs, there is a problem that the transfer is not done well due to their small size, and the picked-up donor substrate cannot be used more than once. After the transfer or stamping, the existing donor substrate must be removed and another temporary substrate inserted, which makes the process cumbersome. In addition, when transferring the display elements, adhesive layers with locally different adhesive strengths are used to adhere the display elements to specific positions. In this case, problems may arise in that the display elements are not sufficiently attached to the desired transfer position or are attached to an undesirable position.

[0111] A display device according to one embodiment of this specification includes an adhesive layer comprising a first region and a second region corresponding to a light-emitting element. In this case, the first region is a region that adheres to the light-emitting element and has a low tanδ value, and the second region is a region that does not adhere to the light-emitting element and has a higher tanδ value than the first region. By using an adhesive layer having such characteristics, process errors in which the light-emitting element is attached to an undesirable region can be reduced, and process yield can be improved.

[0112] On the other hand, referring to Figure 2, multiple uneven patterns may be formed on the underside of the light-emitting element. These uneven patterns are formed during the manufacturing of the light-emitting element, either by cutting the semiconductor layer grown on the wafer or during the primary transfer to the donor substrate. The uneven patterns formed on the underside of the light-emitting element reduce the adhesion strength with the adhesive layer during the secondary transfer from the donor substrate to the display panel. When the light-emitting element is secondary transferred to the display panel, the underside of the light-emitting element with the uneven pattern comes into direct contact with the adhesive layer, and at this time, voids may occur in the uneven pattern between the adhesive layer and the light-emitting element. The voids formed in the uneven pattern significantly reduce the adhesion strength between the adhesive layer and the light-emitting element, which causes transfer failure of the light-emitting element.

[0113] In one embodiment of the display device according to this specification, the adhesive layer has a light-emitting element placed in a first region having a low tanδ, in which case the generation 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 configuration will be explained in more detail below through examples and comparative examples. However, the following examples are illustrative for the purposes of this specification and do not limit the scope of this 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 tanδ monomer (A, first functional monomer), 3 parts by weight of pentaerythritol tetraacrylate as a high tanδ monomer (B, second functional monomer), 0.5 parts by weight of 4,4'-bis(dimethylamino)benzophenone as a photosensitive agent, and 76.5 parts by weight of propylene glycol monomethyl ether acetate as a solvent. The prepared adhesive composition was coated onto a substrate to a thickness of 3.5 μm, dried in a 40 Pa vacuum chamber for 30 seconds, further dried on a 90°C hot plate for 10 seconds, and then exposed to ultraviolet light at 100 mJ / cm² using a mask. 2The material was irradiated with [a specific light source]. At this time, the thicknesses of the first and second regions were 3.0 μm and 2.7 μm, respectively, and an adhesive layer was formed with a width of 100 μm for each region.

[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 low-tanδ monomers or high-tanδ monomers.

[0117] Experimental Example 1 - Evaluation of Transcription Performance After stamping a 20 μm wide micro-LED once onto the first region of the adhesive layer according to Example 1 and Comparative Example 1, the number of micro-LEDs transferred to the first region and the number of micro-LEDs transferred to the second region were confirmed. The transfer results are shown in Table 1 below.

[0118] Experimental Example 2 - Evaluation of Transcriptional Characteristics After the micro-LED transfer process, a cross-section of the micro-LED transferred to the first region and the adhesive layer was photographed with an optical microscope to confirm 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] Furthermore, after the micro-LED transfer process, the area on the upper surface of the display panel where the micro-LEDs were attached and the adjacent area were photographed to confirm whether or not the uneven pattern formed on the underside of the micro-LEDs was visible. Figures 7a and 7b are images evaluating the transfer defects in Comparative Example 1 and Example 1. [Table 1]

[0120] Referring to Table 1, it was confirmed that in Example 1, compared to Comparative Example 1, the defect of the light-emitting element being incorrectly transferred to the second region was eliminated, resulting in an improved process yield. On the other hand, referring to Figure 6a, in the case of Comparative Example 1, it was confirmed that multiple uneven patterns were formed on the lower surface of the light-emitting element in cross-section, and that a void V was formed in the uneven pattern between the adhesive layer and the light-emitting element. In this case, the height of the void was 46 relative to the height of the uneven pattern, confirming that a large void was formed in the uneven pattern. In contrast, referring to Figure 6b, it was confirmed that in the case of Example 1, almost no void was formed in the uneven pattern between the adhesive layer and the light-emitting element, and it was hardly visible in the image. In this case, the height of the void was 3 relative to the height of the uneven pattern, confirming that the size of the void was significantly smaller compared to Comparative Example 1.

[0121] Furthermore, referring to Figure 7a, in Comparative Example 1, the uneven pattern formed on the underside of the micro-LED created a brightness difference (8%) at the boundary between the area where the micro-LED was formed and the area where it was not, and it was confirmed that the boundary BL of the area where the micro-LED was formed was visible. In contrast, referring to Figure 7b, in Example 1, as confirmed in Figure 6b, the void formation was minimal, and it was confirmed that the boundary of the area where the micro-LED was formed was not visible to the naked eye.

[0122] Experimental Example 3 - Transfer Performance Based on Functional Monomer Content In the following, the transfer performance was evaluated by varying the content of low-tanδ monomers and high-tanδ monomers 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, the adhesive layer was formed in the same manner as in Example 1, except that the content of diurethane dimethacrylate as the low tanδ monomer (A, first functional monomer) and pentaerythritol tetraacrylate as the high tanδ monomer (B, second functional monomer) was 2 parts by weight and 1 part by weight, respectively.

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

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

[0126] Comparative Example 2 In Comparative Example 2, the adhesive layer was formed in the same manner as in Example 1, except that only diurethane dimethacrylate was included as the low tanδ monomer (A, first functional monomer) in an amount of 2 parts by weight, and the high tanδ monomer (B, second functional monomer) was not used.

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

[0128] Referring to Table 2 above, it was confirmed that when high tanδ monomers are not included, light-emitting elements are mistakenly transferred to the second region as well. Furthermore, it was confirmed that even when low tanδ monomers and high tanδ monomers are included in the same ratio, if the total content of functional monomers is 70% or more based on the binder resin, the effect of selectively preventing transfer to the second region is somewhat reduced. The various embodiments of this specification may be described as follows. A display device according to one embodiment of this specification includes a substrate containing a plurality of subpixels; a thin-film transistor disposed on the substrate; an adhesive layer disposed on the thin-film transistor and containing a first region and a second region having a higher tanδ 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 other features of this specification, the tanδ value of the first region may be 0.01 or less, and the tanδ value of the second region may be between 0.08 and 0.2.

[0130] According to other features of this specification, the second region may have a higher degree of hardening than the first region.

[0131] According to other features of this specification, the adhesive layer may include a binder resin, a photosensitive agent, and a first and second functional monomer having different tanδ values ​​from each other.

[0132] According to other features of this specification, the first functional monomer is diurethane dimethacrylate, polyethylene glycol dimethacrylate, bisphenol A(EO)10 diacrylate, bisphenol A(EO)30 diacrylate, tricyclodecanedimethanol 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 It may contain one or more selected from the group consisting of isocyanurate diacrylate, butyrate hydroxyanisole, 2,6-di-tert-butyl-4-hydroxymethylphenol, butyrate 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 other features of this specification, the second functional monomer may include 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.

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

[0135] According to another feature of this specification, the upper surface of the first region may protrude from the upper surface of the second region toward a plurality of light-emitting elements.

[0136] According to other features of this specification, a stepped structure may be further included, which is located beneath the adhesive layer and includes protrusions that project toward a plurality of light-emitting elements corresponding to the first region.

[0137] According to other features of this specification, the stepped structure further includes a planarization layer disposed on a thin-film transistor, a plurality of reflectors disposed on the planarization layer and connected to each of a plurality of light-emitting elements, and a passivation layer disposed between the plurality of reflectors and an adhesive layer, wherein the stepped 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 other features of this specification, the stepped structure further includes a planarization layer disposed on a thin-film transistor; a plurality of reflectors disposed on the planarization layer and connected to each of the plurality of light-emitting elements; and a passivation layer disposed between the plurality of reflectors and an adhesive layer, wherein the stepped structure may be formed of the passivation layer.

[0139] According to other features of this specification, an uneven pattern may be formed on the underside of each of the multiple light-emitting elements.

[0140] According to other features of this specification, a void is formed between the adhesive layer and the uneven pattern, and the ratio of the height of the void to the height of the uneven pattern may be 5 or less.

[0141] According to other features of this specification, the lower surfaces of multiple light-emitting elements in the first region can all be in contact with the adhesive layer so as not to form a gap between the adhesive layer and the uneven pattern.

[0142] According to other features of this specification, each of the plurality of light-emitting elements includes a first semiconductor layer on an adhesive layer, a second semiconductor layer disposed on the first semiconductor layer, a light-emitting layer disposed between the first and second semiconductor layers, a first electrode disposed on the first semiconductor layer and separated from the light-emitting layer, and a second electrode disposed on the second semiconductor layer, wherein the lower surface of the first semiconductor layer may be in direct contact with a first region of the adhesive layer.

[0143] Although embodiments of this specification have been described in more detail above with reference to the attached drawings, this specification is not necessarily limited to these embodiments and can be modified and implemented in various ways without deviating from the technical concept of this specification. Therefore, the embodiments disclosed herein are for illustrative purposes only, not to limit the technical concept of this specification, and the scope of the technical concept of this specification is not limited by such embodiments. Accordingly, the embodiments described above should be understood in all respects as illustrative and not limiting. The scope of protection of this specification should be interpreted as defined by the claims, and all technical concepts within an equivalent scope should be interpreted as being included in the scope of rights of this specification. [Explanation of Symbols]

[0144] 100 display device 110 circuit boards 120 Adhesive layer

Claims

1. A substrate containing multiple subpixels, A thin-film transistor arranged on the substrate, An adhesive layer disposed on the thin-film transistor, including a first region and a second region provided adjacent to the first region on the same plane, having a higher tanδ value than the first region, It includes a plurality of light-emitting elements arranged in the first region of the adhesive layer, corresponding to the plurality of subpixels, The tanδ value is N / mm ２ A display device that provides a dimensionless value obtained by dividing the press-fit hardness value, calculated in units, by the press-fit modulus value, calculated in MPa units.

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

2.

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

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

5. The first functional monomer is diurethane dimethacrylate, polyethylene glycol dimethacrylate, bisphenol A (EO) 10 diacrylate, bisphenol A (EO) 30 diacrylate, tricyclodecanedimethanol 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 di The display device according to claim 4, comprising one or more selected from the group consisting of acrylate, butyrate hydroxyanisole, 2,6-di-tert-butyl-4-hydroxymethylphenol, butyrate 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. The display device according to claim 4, wherein the second functional monomer comprises 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.

7. The display device according to claim 4, wherein the total content of the first functional monomer and the second functional monomer combined 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 the upper surface of the first region protrudes from the upper surface of the second region toward the plurality of light-emitting elements.

9. The display device according to claim 8, further comprising a stepped structure disposed below the adhesive layer and including a protruding portion that protrudes toward the plurality of light-emitting elements corresponding to the first region.

10. A planarization layer disposed on the thin-film transistor, A plurality of reflectors are arranged on the planarization layer and connected to each of the plurality of light-emitting elements, The present invention further includes a passivation layer disposed between the plurality of reflectors and the adhesive layer, The display device according to claim 9, wherein the stepped 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 are arranged on the planarization layer and connected to each of the plurality of light-emitting elements, A passivation layer disposed between the plurality of reflectors and the adhesive layer. It further includes, The display device according to claim 9, wherein the stepped structure is formed of the passivation layer.

12. The display device according to claim 1, wherein an uneven pattern is formed on the lower surface of each of the plurality of light-emitting elements.

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

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

15. Each of the aforementioned plurality of light-emitting elements is The 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 is disposed on the first semiconductor layer and separated from the light-emitting layer, The second electrode is disposed on the second semiconductor layer, The display device according to claim 12, wherein the lower surface of the first semiconductor layer is in direct contact with the first region of the adhesive layer.

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

2.

17. A substrate including a plurality of subpixels, A thin-film transistor arranged on the substrate, An adhesive layer comprising one or more subpatterns and disposed on the thin-film transistor, A plurality of light-emitting elements are arranged on the adhesive layer corresponding to the plurality of subpixels. Equipped with, The plurality of subpatterns of the adhesive layer have a tanδ value lower than the average tanδ value of the entire adhesive layer, and the plurality of light-emitting elements are aligned with the subpatterns of the adhesive layer. The tanδ value is N / mm ２ A display device characterized by being a dimensionless value obtained by dividing the press-fit hardness value calculated in units by the press-fit modulus value calculated in MPa units.

18. The display device according to claim 17, wherein the plurality of subpatterns of the adhesive layer have a tanδ value that is at least 0.05 lower than the tanδ value of other regions of the adhesive layer.

19. The display device according to 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 is capable of forming a surface having a higher tanδ value than the first functional monomer, and the total content of functional monomers including the first functional monomer is capable of forming a surface having a higher tanδ value than the first functional monomer.

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

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