Display device and method of manufacturing the same

Abstract

A display device and a method of manufacturing the display device are provided. The display device includes a first electrode provided over a substrate, a binding auxiliary layer including a self-assembled monolayer provided over the first electrode, a light emitting element provided over the binding auxiliary layer, and a contact electrode provided between the binding auxiliary layer and the light emitting element. The light emitting element includes a first semiconductor layer, a second semiconductor layer provided over the first semiconductor layer, and an intermediate layer provided between the first semiconductor layer and the second semiconductor layer.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2019-0128023, filed on October 15, 2019, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a display device and a method of manufacturing the display device. Background Technology

[0004] Display devices use light-emitting elements such as light-emitting diodes (LEDs) to display images. LEDs exhibit relatively excellent durability even in harsh environmental conditions and demonstrate superior performance in terms of lifespan and brightness.

[0005] Light-emitting diodes (LEDs) can be attached to a substrate via chip bonding or solder reflow processes, which are assembly processes performed using eutectic compound metals. Typically, processes such as coating the substrate with flux are required to improve the adhesion between the LED and the substrate; however, residual flux can lead to metal corrosion or out-gassing, which can cause illumination defects in the display device. Summary of the Invention

[0006] A display device capable of improving the bonding force between the light-emitting diode and the substrate and preventing illumination defects, and a method for manufacturing the display device are disclosed.

[0007] The display device according to an embodiment may include a plurality of pixels disposed on a substrate, each of the plurality of pixels including a first electrode disposed on the substrate, an adhesive assist layer disposed on the first electrode and including a self-assembly monolayer, a light-emitting element disposed on the adhesive assist layer, and a contact electrode disposed between the adhesive assist layer and the light-emitting element. The light-emitting element may include a first semiconductor layer, a second semiconductor layer disposed on the first semiconductor layer, and an intermediate layer disposed between the first semiconductor layer and the second semiconductor layer.

[0008] The adhesive aid layer can consist of a self-assembling monolayer.

[0009] The surface of the adhesive auxiliary layer can be in direct contact with the first electrode, and the other surface of the adhesive auxiliary layer can be in direct contact with the contact electrode.

[0010] The adhesive aid layer can cover the upper and side surfaces of the first electrode.

[0011] The adhesive auxiliary layer can be continuously applied to cover the first electrode across multiple pixels.

[0012] The adhesion auxiliary layer can include a siloxane compound.

[0013] The adhesion auxiliary layer can include a hydrophilic functional group or a hydrophobic functional group.

[0014] The adhesion auxiliary layer can form a silicon-oxygen (Si-O) bond with a surface of the first electrode.

[0015] The display device can further include an insulating layer disposed between the substrate and the first electrode, and the adhesion auxiliary layer can be in direct contact with the insulating layer.

[0016] The adhesion auxiliary layer can form a silicon-oxygen (Si-O) bond with a surface of the insulating layer.

[0017] The display device can further include a source electrode and a drain electrode disposed between the substrate and the insulating layer, and the first electrode can be electrically connected to the source electrode or the drain electrode through a contact hole passing through the insulating layer.

[0018] A surface of the contact electrode can be in direct contact with the adhesion auxiliary layer, and another surface of the contact electrode can be in direct contact with the first semiconductor layer.

[0019] The display device can further include a second electrode disposed on the first electrode, and the light emitting element can be disposed between the first electrode and the second electrode.

[0020] The first electrode can include at least one of copper (Cu) and gold (Au).

[0021] The light emitting element can be a micro light emitting diode having one side whose length can be equal to or less than about 100 µm.

[0022] The method of manufacturing a display device according to an embodiment can include forming a first electrode on a substrate, forming a self-assembled monolayer on the first electrode, and attaching a micro light emitting diode on the self-assembled monolayer.

[0023] The method can further include forming a contact electrode on a surface of the micro light emitting diode, and the attaching the micro light emitting diode can include attaching the contact electrode on the self-assembled monolayer to dispose the contact electrode between the micro light emitting diode and the self-assembled monolayer.

[0024] The forming the self-assembled monolayer can include forming a self-assembled material layer on the first electrode, and chemisorbing the self-assembled material layer on a surface of the first electrode.

[0025] The forming the self-assembled material layer can include at least one of dip coating, spin coating, slot coating, inkjet printing, and vapor deposition.

[0026] The self-assembled material layer can include at least one of APS [(3-aminopropyl)trimethoxysilane], MUA (11-mercaptoundecanoic acid), DET [(3-trimethoxysilylpropyl)diethylenetriamine], EDA [N-(2-aminoethyl)-3-aminopropyltrimethoxysilane], PFS (perfluorodecyltrichlorosilane), OTS (octadecyltrichlorosilane), OTMS (octadecyltrimethoxysilane), HDT (1-hexadecanethiol), FDTS [(heptadecafluoro-1,1,2,2,-tetrahydrodecyl)trichlorosilane], FOTS (1H,1H,2H,2H-perfluorodecyltrichlorosilane-perfluorodecyltrichlorosilane), PFBT (pentafluorobenzenethiol), and DDMS (dichlorodimethylsilane).

[0027] Forming the self-assembled monolayer can include forming a silicon-oxygen (Si-O) bond with a surface of the first electrode.

[0028] According to embodiments of the disclosure, the adhesion between the light emitting diode and the substrate can be improved by forming the adhesion auxiliary layer on the first electrode of the substrate. Accordingly, a flux coating process can be omitted, and thus, occurrence of illumination defects of the display device due to residual flux can be minimized.

[0029] Effects according to embodiments are not limited to the explanations mentioned above. Other different effects are also included in the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above and other features of the disclosure will become more apparent by describing in detail embodiments thereof with reference to the attached drawings, in which:

[0031] Figure 1 is a schematic plan view schematically showing a display device according to an embodiment;

[0032] Figure 2 is a schematic sectional view showing a pixel according to an embodiment;

[0033] Figure 3 is a schematic plan view schematically showing a display device according to an embodiment; Figure 2 is a magnified view of a region A of

[0034] Figure 4 is a magnified view of a region B of Figure 3

[0035] Figure 5 is a schematic sectional view showing a pixel according to another embodiment;

[0036] Figure 6 is a magnified view of a region C of Figure 5

[0037] Figures 7 to 11 ​​is a schematic cross-sectional view illustrating a process step of a method of manufacturing a display device according to an embodiment. DETAILED DESCRIPTION

[0038] The advantages and features of the present disclosure and a method for achieving the same will become apparent from the detailed description of embodiments given below with reference to the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and can be implemented in diverse forms. The embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. The present disclosure is defined only by the scope of the claims.

[0039] When an element or layer is referred to as being "on" another element or layer, it can be "directly on" the other element or layer, or intervening elements or layers can also be present. It will also be understood that when an element or layer is referred to as being "under" or "beneath" another element or layer, it can be "directly under" the other element or layer, or intervening elements or layers can also be present. When an element or layer is referred to as being disposed on another element or layer, it can be disposed below the other element or layer.

[0040] Throughout the specification, like drawing reference numerals refer to like parts throughout the specification.

[0041] Although first, second, etc. are used herein to describe various elements, it should be understood that these elements are not limited by these terms. These terms are used only to distinguish one element from another. It will be understood that the first element referenced below can be a second element within the technical spirit of the present disclosure. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0042] It will be further understood that the terms "comprises" and / or "comprising", "includes" and / or "including" when used in this specification, specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

[0043] The phrase "at least one of" followed by a list of two or more items, such as "at least one of A and B", is understood to mean A or B or both A and B. When the term "at least one of" is used in the context of a list of two or more items, it is understood that the term "at least one of" applies to each of the items in the list.

[0044] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0045] In this specification, a first direction DR1 denotes an X-axis direction, a second direction DR2 denotes a Y-axis direction, and a third direction DR3 denotes a Z-axis direction.

[0046] Figure 1 is a schematic plan view schematically showing a display device according to an embodiment.

[0047] Referring to Figure 1 The display device 1000 can be applied to various electronic devices, including small- and medium-sized electronic devices such as a tablet personal computer (PC), a smart phone, a car navigation unit, a camera, a center information display (CID) provided to a car, a wristwatch-type electronic device, a personal digital assistant (PDA), a portable multimedia player, or a game console, and medium- and large-sized electronic devices such as a television, an outdoor billboard, a monitor, a personal computer, or a notebook computer. These are provided by way of example only, and the display device 1000 can be used in other electronic devices without departing from the idea of the present disclosure.

[0048] The substrate SUB can have a planar rectangular shape. The substrate SUB can include a short side extending in one direction (e.g., the first direction DR1) and a long side extending in another direction (e.g., the second direction DR2) crossing the one direction. A corner portion where the long side and the short side of the substrate SUB intersect can be a right angle in a planar surface (or in a plan view). However, the shape of the corner portion is not limited thereto and can have a rounded curved shape. The planar shape of the substrate SUB is not limited to the illustrated shape, but can be implemented as a square, a circle, an ellipse, or other shapes.

[0049] The substrate SUB can include a display area DA in which an image is displayed and a non-display area NDA in which an image is not displayed.

[0050] The display area DA can be an area in which the pixels PXL are disposed. The display area DA can be disposed on a front surface or a side surface of the substrate SUB, and a planar shape of the display area DA can follow a planar shape of the substrate SUB.

[0051] The non-display area NDA can be an area in which a driver for driving the pixels PXL and various wiring portions (not shown) connecting the pixels PXL and the driver are disposed. The non-display area NDA can be disposed on at least one side of the display area DA. For example, the non-display area NDA can be disposed to surround the display area DA.

[0052] The pixels PXL can be provided on the substrate SUB in the display area DA. Each of the pixels PXL can emit one of red, green, and blue, but is not limited thereto. For example, each of the pixels PXL can emit one of cyan, magenta, yellow, and white.

[0053] The pixels PXL can be arranged in a matrix form while forming rows and columns along a first direction DR1 and a second direction DR2 intersecting the first direction DR1. However, the arrangement of the pixels PXL is not limited to the arrangement shown in Figure 1 and can be modified into various forms.

[0054] The driver can generate a driving signal required to drive the pixels PXL and provide the driving signal to the pixels PXL. The driver can include a scan driver SDV that provides a scan signal to the pixels PXL through a scan line, a light emission driver EDV that provides a light emission control signal to the pixels PXL through a light emission control line, a data driver DDV that provides a data signal to the pixels PXL through a data line, and a timing controller that controls the scan driver SDV, the light emission driver EDV, and the data driver DDV. In Figure 1 , the scan driver SDV, the light emission driver EDV, and the data driver DDV are positioned in the non-display area NDA, but in another embodiment, the driver can be positioned outside the substrate SUB.

[0055] The pixel PXL can include at least one light emitting element that is driven by a corresponding scan signal and data signal. A detailed description of the light emitting element will be given later with reference to Figure 2 and Figure 3 .

[0056] Figure 2 is a schematic cross-sectional view illustrating a pixel according to an embodiment. Figure 3 is Figure 2 an enlarged view of the area A of

[0057] Referring to Figure 2 and Figure 3 , the pixel PXL can include a substrate SUB, a thin film transistor layer TFTL, a light emitting element layer EML, and a thin film encapsulation layer TFEL.

[0058] The substrate SUB can be a flexible substrate that can be bent, folded, folded, or curled. Examples of materials for the flexible substrate can include polyether sulfone (PES), polyacrylate (PA), polyarylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polyimide (PI), polycarbonate (PC), cellulose triacetate (CAT), cellulose acetate propionate (CAP), or a combination thereof.

[0059] The thin film transistor layer TFTL can be disposed on the substrate SUB. The thin film transistor layer TFTL can be disposed in the display area DA and the non-display area NDA.

[0060] The thin film transistor layer TFTL can include a buffer layer BF, an active layer ACT, a first insulating layer IL1, a first conductive layer 110, a second insulating layer IL2, a second conductive layer 120, and a third insulating layer IL3.

[0061] Each of the above layers can be formed of a single film, but can also be formed of a stacked film including a plurality of films. Other layers can be further disposed between each of the layers.

[0062] The buffer layer BF can be disposed on the substrate SUB. The buffer layer BF can prevent diffusion of impurity ions, prevent penetration of moisture, and perform a surface planarization function. The buffer layer BF can include silicon nitride, silicon oxide, silicon oxynitride, or the like.

[0063] The active layer ACT can be disposed on the buffer layer BF. The active layer ACT forms a channel of a thin film transistor of the pixel PXL. The active layer ACT can include polysilicon. The polysilicon can be formed by crystallizing amorphous silicon.

[0064] When the active layer ACT can be formed of polysilicon, the ion-doped active layer ACT can have electrical conductivity. Accordingly, the active layer ACT can include a source region and a drain region of the thin film transistor as well as a channel region. The source region and the drain region can be connected to both sides of each channel region.

[0065] In another embodiment, the active layer ACT can include single-crystal silicon, low-temperature polysilicon, amorphous silicon, or an oxide semiconductor. The oxide semiconductor can include, for example, a binary system compound (AB x ), a ternary system compound (AB x C y ), or a quaternary system compound (AB x C y D z). In an embodiment, the active layer ACT can include ITZO (an oxide including indium, tin, and zinc) or IGZO (an oxide including indium, gallium, and zinc).

[0066] A first insulating layer IL1 can be disposed on the active layer ACT. The first insulating layer IL1 can be continuously disposed on a surface (or an entire surface) of the substrate SUB. The first insulating layer IL1 can be a gate insulating film having a gate insulating function. The first insulating layer IL1 can include a silicon compound or a metal oxide. For example, the first insulating layer IL1 can include silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, tantalum oxide, hafnium oxide, zirconium oxide, titanium oxide, or the like. The first insulating layer IL1 can be a single film or a multi-layer film formed of stacked films of different materials.

[0067] A first conductive layer 110 can be disposed on the first insulating layer IL1. The first conductive layer 110 can include at least one metal selected from molybdenum (Mo), aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu). The first conductive layer 110 can be a single film or a multi-layer film. The first conductive layer 110 can include a gate electrode of a thin film transistor of the pixel PXL and a first electrode of a storage capacitor.

[0068] A second insulating layer IL2 can be disposed on the first conductive layer 110. The second insulating layer IL2 can be continuously disposed on a surface (or an entire surface) of the substrate SUB. The second insulating layer IL2 can function to insulate the first conductive layer 110 and the second conductive layer 120.

[0069] The second insulating layer IL2 can include the same material as the above-described first insulating layer IL1, or can include at least one material selected from the materials exemplified as the configuration material of the first insulating layer IL1.

[0070] A second conductive layer 120 can be disposed on the second insulating layer IL2. The second conductive layer 120 can include a metal selected from aluminum (Al), molybdenum (Mo), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu). The second conductive layer 120 can be a single film or a multi-layer film. For example, the second conductive layer 120 can be formed of a stacked structure of Ti / Al / Ti, Mo / Al / Mo, Mo / Al / Ge / Mo, Ti / Cu, or the like.

[0071] The second conductive layer 120 can include a source electrode 121 and a drain electrode 122 of a thin film transistor. The source electrode 121 and the drain electrode 122 can be connected to a source region and a drain region of the active layer ACT, respectively, through contact holes passing through the second insulating layer IL2 and the first insulating layer IL1.

[0072] The third insulating layer IL3 covers the second conductive layer 120. The third insulating layer IL3 can be a via layer. The third insulating layer IL3 can include an organic insulating material such as an acrylic resin (such as a polyacrylate resin), an epoxy resin, a phenol resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin, a polyphenylene ether resin, a polyphenylene sulfide resin, or benzocyclobutene (BCB).

[0073] The light emitting element layer EML can be disposed on the thin film transistor layer TFTL. The light emitting element layer EML can be disposed in the display area DA. However, the present disclosure is not limited thereto, and the light emitting element layer EML can be disposed in the non-display area NDA.

[0074] The light emitting element layer EML can include a first electrode 130, an adhesion auxiliary layer AL, a light emitting element LED, and a second electrode 140.

[0075] The first electrode 130 can be disposed on the third insulating layer IL3. The first electrode 130 can have a stacked film structure of material layers having a high work function such as copper (Cu), gold (Au), silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), lead (Pb), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), a mixture thereof, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), and combinations thereof. However, the present disclosure is not limited thereto.

[0076] The first electrode 130 can be electrically connected to the thin film transistor. For example, the first electrode 130 can be electrically connected to the drain electrode 122 through a contact hole passing through the third insulating layer IL3. The anode electrode of the pixel PXL can be formed of the first electrode 130. In another embodiment, the first electrode 130 can also be electrically connected to the source electrode 121 through a contact hole passing through the third insulating layer IL3.

[0077] The adhesion auxiliary layer AL can be disposed on the first electrode 130. The adhesion auxiliary layer AL can be directly disposed on one surface of the first electrode 130. The adhesion auxiliary layer AL can be disposed to cover the upper surface and the side surface of the first electrode 130. For example, the adhesion auxiliary layer AL can be in contact (e.g., direct contact) with the upper surface and the side surface of the first electrode 130.

[0078] The adhesion auxiliary layer AL can be continuously disposed to cover a surface (or an entire surface) of the substrate SUB. The adhesion auxiliary layer AL can be continuously disposed to cover the first electrode 130 of the pixel PXL. The adhesion auxiliary layer AL can be in contact (e.g., direct contact) with the third insulating layer IL3 disposed under the first electrode 130.

[0079] The adhesion auxiliary layer AL includes a self-assembled monolayer (SAM). In an embodiment, the adhesion auxiliary layer AL can consist of a self-assembled monolayer. For example, the adhesion auxiliary layer AL can be an organic monolayer spontaneously formed on a surface of the first electrode 130. The adhesion auxiliary layer AL can be regularly arranged on the surface of the first electrode 130. Referring to Figure 4 The same will be described in detail.

[0080] Figure 4 is Figure 3 an enlarged view of the region B of

[0081] Referring to Figure 4 , the adhesion auxiliary layer AL can be chemisorbed on the surface of the first electrode 130. For example, the adhesion auxiliary layer AL can include a reaction part of a head that can be coupled with the first electrode 130, an alkyl chain of a main part capable of forming a regular molecular film, and a functional group of a tail.

[0082] The reaction part of the adhesion auxiliary layer AL can be chemisorbed on the surface of the first electrode 130. The reaction part of the adhesion auxiliary layer AL can form a direct chemical bond with the surface of the first electrode 130.

[0083] For example, the adhesion auxiliary layer AL can include a siloxane compound as an alkylsiloxane self-assembled monolayer. The reaction part of the adhesion auxiliary layer AL can form a silicon-oxygen (Si-O) bond with the surface of the first electrode 130. However, the disclosure is not limited thereto, and the adhesion auxiliary layer AL can include a phosphonate compound as a phosphonic alkyl ester self-assembled monolayer. The reaction part of the adhesion auxiliary layer AL can form a phosphorus-oxygen (P-O) bond with the surface of the first electrode 130.

[0084] The alkyl chain of the adhesion auxiliary layer AL can be formed of a substituted or unsubstituted C1-C 20 alkyl group. Due to Van der Waals interaction between the alkyl chains of the adhesion auxiliary layer AL, an aligned monolayer can be formed on the surface of the first electrode 130.

[0085] The functional group of the adhesion auxiliary layer AL can have a hydrophilic functional group or a hydrophobic functional group for controlling a surface property of the first electrode 130.

[0086] For example, the adhesion auxiliary layer AL having a hydrophilic functional group can include, for example, APS [(3-aminopropyl)trimethoxysilane], MUA (11-mercaptoundecanoic acid), DET [(3-trimethoxysilylpropyl)diethylenetriamine], EDA [N-(2-aminoethyl)-3-aminopropyltrimethoxysilane], and combinations thereof, but is not limited thereto.

[0087] The adhesion auxiliary layer AL having a hydrophobic functional group can include, for example, VTES (vinyltriethoxysilane), GPTMS (3-glycidoxypropyltrimethoxysilane), MPTMS (3-methacryloyloxypropyltrimethoxysilane), PFS (perfluorodecyltrichlorosilane), OTS (octadecyltrichlorosilane), OTMS (octadecyltrimethoxysilane), HDT (1-hexadecanethiol), FDTS [(heptadecafluoro-1,1,2,2,-tetrahydrodecyl)trichlorosilane], FOTS (1H,1H,2H,2H-perfluorodecyltrichlorosilane-perfluorodecyltrichlorosilane), PFBT (pentafluorobenzenethiol), DDMS (dichlorodimethylsilane), and combinations thereof, but is not limited thereto.

[0088] As described above, when the adhesion auxiliary layer AL is adsorbed (e.g., chemisorbed) on the surface of the first electrode 130 to form a self-assembled monolayer, the surface properties of the first electrode 130 can be easily controlled. Accordingly, the surface of the first electrode 130 can be prevented from being oxidized, lubricity and wettability can be improved, and the binding force between the first electrode 130 and the light emitting element LED (which will be described later) can be improved.

[0089] Figure 4 Only an example in which the adhesion auxiliary layer AL is adsorbed (e.g., chemisorbed) on the surface of the first electrode 130 is illustrated. However, similarly, the adhesion auxiliary layer AL can form a direct chemical bond with the surface of the third insulating layer IL3. However, embodiments are not limited thereto.

[0090] For example, when the adhesion auxiliary layer AL is an alkylsiloxane self-assembled monolayer, the reaction portion of the adhesion auxiliary layer AL can form a silicon-oxygen (Si-O) bond with the surface of the third insulating layer IL3.

[0091] When the adhesion auxiliary layer AL is a phosphonic acid alkyl ester self-assembled monolayer, the reaction portion of the adhesion auxiliary layer AL can form a phosphorus-oxygen (P-O) bond with the surface of the third insulating layer IL3. Since details of the adhesion auxiliary layer AL have been described with reference to Figure 4 Since details of the adhesion auxiliary layer AL have been described, a repeated description thereof will be omitted.

[0092] The light emitting element LED and the planarization layer PL can be disposed on the first electrode 130.

[0093] Referring to Figure 3The light emitting element LED can include a first semiconductor layer L1, a second semiconductor layer L2, and an intermediate layer L3. The intermediate layer L3 can be disposed between the first semiconductor layer L1 and the second semiconductor layer L2. Hereinafter, the light emitting element LED will be described based on an example of a vertical light emitting diode in which the first semiconductor layer L1, the intermediate layer L3, and the second semiconductor layer L2 can be sequentially stacked. However, embodiments are not limited thereto.

[0094] For example, the first semiconductor layer L1 can be formed by including an n-type semiconductor layer. The n-type semiconductor layer can be selected from a semiconductor material having a composition formula of In x Al y Ga (1-x-y) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) (e.g., GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc.), and can be doped with an n-type dopant such as Si, Ge, or Sn.

[0095] For example, the second semiconductor layer L2 can be implemented by a p-type semiconductor layer. The p-type semiconductor layer can be selected from a semiconductor material having a composition formula of In x Al y Ga (1-x-y) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) (e.g., GaN, AlN, AlGaN, InGaN, InN, InAlGaN, AlInN, etc.), and can be doped with a p-type dopant such as Mg, Zn, Ca, Sr, and Ba.

[0096] However, the disclosure is not limited thereto, and the first semiconductor layer L1 can include a p-type semiconductor layer, and the second semiconductor layer L2 can include an n-type semiconductor layer.

[0097] The intermediate layer L3 can be a region in which electrons and holes are recombined. When the electrons and the holes are recombined, the intermediate layer L3 is converted to a low energy level, and light having a corresponding wavelength can be generated. For example, the intermediate layer L3 can be formed by including a semiconductor material having a composition formula of In x Al y Ga (1-x-y) N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).

[0098] Figure 3Embodiments in which the intermediate layer L3 is composed of a single quantum structure are shown, but are not limited thereto. For example, the intermediate layer L3 can be a multiple quantum well structure (MQW). The intermediate layer L3 can be formed of a multi-layer structure in which an active layer and an insulating layer are alternately stacked, and the active layer and the insulating layer can have the same thickness. However, the present disclosure is not limited thereto, and the intermediate layer L3 can be an asymmetric quantum well structure (AQW) in which the active layer and the insulating layer have different thicknesses therein.

[0099] In embodiments, the light emitting element LED can be a micro light emitting diode (micro LED) having a size in units of micrometers (μm). For example, a length of one side of the light emitting element LED can be less than or equal to about 100 μm, but is not limited thereto.

[0100] The light emitting element LED can be electrically connected to the thin film transistor through the first electrode 130. A contact electrode CT can be further provided between the light emitting element LED and the first electrode 130.

[0101] The contact electrode CT can be provided between the adhesion-assisting layer AL including a self-assembled monolayer and the first semiconductor layer L1 of the light emitting element LED. A surface of the contact electrode CT can be in contact (e.g., direct contact) with the adhesion-assisting layer AL, and another surface of the contact electrode CT can be in contact (e.g., direct contact) with the first semiconductor layer L1.

[0102] As described above, the corrosion resistance, lubricity, and wettability of the first electrode 130 can be improved by the adhesion-assisting layer AL. Thus, since the contact electrode CT can be easily attached on the first electrode 130, the bonding force between the first electrode 130 and the light emitting element LED can be improved as described above.

[0103] The contact electrode CT can include a metal or a metal oxide. For example, the contact electrode CT can include chromium (Cr), titanium (Ti), aluminum (Al), gold (Au), nickel (Ni), indium tin oxide (ITO), an oxide thereof, an alloy thereof, or the like, but is not limited thereto.

[0104] The planarization layer PL can be provided to surround the light emitting element LED. The planarization layer PL can be used to prevent a step difference due to the light emitting element LED.

[0105] The planarization layer PL can include an organic insulating material such as an acrylic resin (e.g., a polyacrylate resin), an epoxy resin, a phenol resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin, a polyphenylene ether resin, a polyphenylene sulfide resin, or benzocyclobutene (BCB).

[0106] The second electrode 140 can be disposed on the light emitting element LED and the planarization layer PL. The second electrode 140 can be continuously disposed on the light emitting element LED and the planarization layer PL.

[0107] The second electrode 140 can be formed of a thin film of a metal having a small work function, such as Li, Ca, LiF / Ca, LiF / Al, Al, Mg, Ag, Pt, Pd, Ni, Au, Nd, Ir, Cr, BaF, Ba, or a compound or a mixture thereof (e.g., a mixture of Ag and Mg, etc.). The second electrode 140 can further include a transparent metal oxide layer disposed on a layer of a material having a small work function. Accordingly, the second electrode 140 can transmit light emitted from the light emitting element LED. The cathode electrode of the pixel PXL can be formed of the second electrode 140.

[0108] The thin film encapsulation layer TFEL can be disposed on the light emitting element layer EML. The thin film encapsulation layer TFEL serves to prevent oxygen or moisture from penetrating into the light emitting element layer EML. To this end, the thin film encapsulation layer TFEL can include at least one inorganic film. The inorganic film can include a silicon nitride layer, a silicon oxynitride layer, a silicon oxide layer, a titanium oxide layer, or an aluminum oxide layer, but is not limited thereto.

[0109] The thin film encapsulation layer TFEL serves to protect the light emitting element layer EML from impurities such as dust. To this end, the thin film encapsulation layer TFEL can include at least one organic film. The organic film can include an acrylic resin, an epoxy resin, a phenol resin, a polyamide resin, or a polyimide resin, but is not limited thereto.

[0110] For example, the thin film encapsulation layer TFEL can have a structure in which an inorganic film, an organic film, and an inorganic film are sequentially stacked. The inorganic film can prevent oxygen or moisture from penetrating into the light emitting element layer EML. The organic film can prevent the spread of cracks generated in the inorganic film.

[0111] The thin film encapsulation layer TFEL can be disposed in both the display area DA and the non-display area NDA. For example, the thin film encapsulation layer TFEL can be disposed to cover the light emitting element layer EML in the display area DA and the non-display area NDA, and to cover the thin film transistor layer TFTL in the non-display area NDA.

[0112] As described above, when the adhesion auxiliary layer AL is adsorbed (e.g., chemisorbed) on the surface of the first electrode 130, the surface properties of the first electrode 130 can be easily controlled. Accordingly, since the surface of the first electrode 130 can be prevented from being oxidized and lubricity and wettability can be improved, the bonding force between the first electrode 130 and the light emitting element LED can be improved as described above.

[0113] Hereinafter, another embodiment will be described. In the following embodiment, the same configurations as the configurations already described will be denoted by the same reference numerals, and repetitive description will be omitted or simplified.

[0114] Figure 5 is a schematic cross-sectional view illustrating a pixel according to another embodiment. Figure 6 is Figure 5 is an enlarged view of the region C of

[0115] Referring to Figure 5 and Figure 6 , the display device according to the present embodiment differs from the embodiment of Figures 1 to 4 in that the adhesion-assisting layer AL' is partially disposed on the first electrode 130.

[0116] For example, the adhesion-assisting layer AL' can be directly disposed on one surface of the first electrode 130. The adhesion-assisting layer AL' can be disposed to cover the upper surface and the side surface of the first electrode 130. For example, the adhesion-assisting layer AL' can be in contact (e.g., direct contact) with the upper surface and the side surface of the first electrode 130.

[0117] The adhesion-assisting layer AL' can be a self-assembled monolayer, and can be adsorbed (e.g., chemisorbed) on the surface of the first electrode 130 to form a direct chemical bond with the surface of the first electrode 130. As described above, by controlling the surface properties of the first electrode 130, the binding force between the first electrode 130 and the light-emitting element LED can be improved. A detailed description thereof has been given with reference to Figures 1 to 4 , and thus repetitive description will be omitted.

[0118] The adhesion-assisting layer AL' can be disposed only partially on the surface of the first electrode 130, and can not be disposed on the third insulating layer IL3. The planarization layer PL can be directly disposed on the third insulating layer IL3. For example, the third insulating layer IL3 can be in contact (e.g., direct contact) with the planarization layer PL.

[0119] Since a detailed description of the thin-film transistor layer TFTL, the light-emitting element LED, and the thin-film encapsulation layer TFEL has been given with reference to Figures 1 to 4 , repetitive description thereof will be omitted.

[0120] Subsequently, a method of manufacturing the display device according to the above-described embodiments will be described. In the display device according to various embodiments, a method of manufacturing the display device of Figures 1 to 4 will be described as an example. Components substantially the same as those in Figures 1 to 4 are denoted by the same reference numerals, and detailed description of these same reference numerals will be omitted.

[0121] Figures 7 to 11 is a schematic cross-sectional view illustrating a process step of a method of manufacturing a display device according to an embodiment.

[0122] Referring to Figure 7 , a substrate SUB is prepared, and a thin film transistor layer TFTL and a first electrode 130 can be formed on the substrate SUB. Since the thin film transistor layer TFTL and the first electrode 130 have been described with reference to Figures 1 to 4 , a repeated description thereof will be omitted.

[0123] Referring to Figure 8 , a self-assembled material layer ALM is formed over a surface (or an entire surface) of the substrate SUB.

[0124] As described above, the self-assembled material layer ALM can include a siloxane compound. For example, the self-assembled material layer ALM can include at least one material among APS [(3-aminopropyl)trimethoxysilane], MUA (11-mercaptoundecanoic acid), DET [(3-trimethoxysilylpropyl)diethylenetriamine], EDA [N-(2-aminoethyl)-3-aminopropyltrimethoxysilane], VTES (vinyltriethoxysilane), GPTMS (3-glycidoxypropyltrimethoxysilane), MPTMS (3-methacryloxypropyltrimethoxysilane), PFS (perfluorodecyltrichlorosilane), OTS (octadecyltrichlorosilane), OTMS (octadecyltrimethoxysilane), HDT (1-hexadecanethiol), FDTS [(heptadecafluoro-1,1,2,2,-tetrahydrodecyl)trichlorosilane], FOTS (1H,1H,2H,2H-perfluorodecyltrichlorosilane-perfluorodecyltrichlorosilane), PFBT (pentafluorobenzenethiol), and DDMS (dichlorodimethylsilane).

[0125] The formation of the self-assembled material layer ALM can include liquid deposition or vapor deposition of the self-assembled material.

[0126] The formation of the self-assembled material layer ALM can include at least one method among dip coating, spin coating, slit coating, inkjet printing, and vapor deposition of the self-assembled material, but is not limited thereto.

[0127] Referring to Figure 9The layer of self-assembled material ALM is chemisorbed on the surface of the first electrode 130 to form the adhesion auxiliary layer AL. As described above, the adhesion auxiliary layer AL can consist of a self-assembled monolayer. For example, the adhesion auxiliary layer AL can be an organic monolayer that is spontaneously formed on the surface of the first electrode 130. The reactive portion of the adhesion auxiliary layer AL can form a direct chemical bond with the surface of the first electrode 130. The conformational molecules of the adhesion auxiliary layer AL can be adsorbed (e.g., chemisorbed) on the surface of the first electrode 130 and simultaneously form supramolecular assemblies according to the interactions of the molecules, and thus can prevent the surface of the first electrode 130 from being oxidized, and can improve lubricity and wettability. Accordingly, as described above, the bonding force between the first electrode 130 and the light emitting element LED can be improved.

[0128] Referring to Figure 10 The light emitting element LED is attached on the substrate SUB. For example, the substrate SUB and the light emitting element LED can be coupled to each other by attaching the light emitting element LED on the first electrode 130 on which the adhesion auxiliary layer AL is formed. As described above, the light emitting element LED can be a micro light emitting diode, and can further include a contact electrode disposed on one surface of the first semiconductor layer L1. The attachment of the light emitting element LED can include attaching the contact electrode on the self-assembled monolayer of the adhesion auxiliary layer AL to dispose the contact electrode between the light emitting element LED and the self-assembled monolayer. Since the contact electrode has been described in detail with reference to Figures 1 to 4 The contact electrode has been described in detail, and thus a repeated description thereof will be omitted.

[0129] Referring to Figure 11 The second electrode 140 and the thin film encapsulation layer TFEL are formed on the light emitting element LED.

[0130] The second electrode 140 can be continuously formed by depositing a material for the second electrode 140 on the light emitting element LED and the planarization layer PL. The material for the second electrode 140 can include a material having a small work function for electron injection, such as Li, Ca, LiF / Ca, LiF / Al, Al, Mg, Ag, Pt, Pd, Ni, Au, Nd, Ir, Cr, BaF, Ba, or a compound or a mixture thereof (e.g., a mixture of Ag and Mg, etc.). The material for the second electrode 140 can further include a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), zinc oxide, or tin oxide.

[0131] The thin film encapsulation layer TFEL can be formed on the second electrode 140 to complete the display device including the pixel PXL as shown in Figure 2

[0132] ​Based on the method of manufacturing a display device according to the above-described embodiment, by forming the adhesion auxiliary layer AL on the first electrode 130 of the substrate SUB using a self-assembling material, the bonding force between the light emitting element LED and the substrate SUB can be improved.

[0133] Since the flux coating process required to improve the bonding force can be omitted, metal corrosion or outgassing due to residual flux can be minimized. For example, the bonding force between the light emitting element LED and the substrate SUB can be improved, and the illumination defects of the display device can be minimized.

[0134] Those skilled in the art can understand that the present disclosure can be implemented in modified forms without departing from the essential characteristics described above. Accordingly, the disclosed method should be considered as a descriptive aspect rather than a limiting aspect. The scope of the present disclosure is shown in the claims, not in the above description, and all differences within the scope will be interpreted as included in the present disclosure.

Claims

1. A display device, comprising: Multiple pixels are disposed on a substrate, each of the multiple pixels comprising: A first electrode is disposed on the substrate; An adhesive aid layer is disposed on the first electrode and includes a self-assembled monolayer; a light-emitting element is disposed on the adhesive aid layer, the light-emitting element comprising: First semiconductor layer; A second semiconductor layer is disposed on the first semiconductor layer; and An intermediate layer is disposed between the first semiconductor layer and the second semiconductor layer; and A contact electrode is disposed between the adhesive auxiliary layer and the light-emitting element.

2. The display device according to claim 1, wherein The adhesive auxiliary layer is composed of the self-assembled monolayer.

3. The display device according to claim 1, wherein, The surface of the adhesive aid layer is in direct contact with the first electrode, and The other surface of the adhesive aid layer is in direct contact with the contact electrode.

4. The display device according to claim 1, wherein The adhesive aid layer covers the upper and side surfaces of the first electrode.

5. The display device according to claim 4, wherein, The adhesive aid layer is continuously disposed to cover the first electrode in the plurality of pixels.

6. The display device according to claim 1, wherein, The adhesive aid layer comprises a siloxane compound.

7. The display device according to claim 6, wherein, The adhesive auxiliary layer includes hydrophilic or hydrophobic functional groups.

8. The display device according to claim 5, wherein, The adhesive aid layer forms silicon-oxygen bonds with the surface of the first electrode.

9. The display device according to claim 1, further comprising: An insulating layer is disposed between the substrate and the first electrode. The adhesive aid layer is in direct contact with the insulating layer.

10. The display device according to claim 9, wherein, The adhesive aid layer forms silicon-oxygen bonds with the surface of the insulating layer.

11. The display device according to claim 9, further comprising: The source electrode and drain electrode are disposed between the substrate and the insulating layer. The first electrode is electrically connected to the source electrode or the drain electrode through a contact hole passing through the insulating layer.

12. The display device according to claim 1, wherein, The surface of the contact electrode is in direct contact with the adhesive aid layer, and The other surface of the contact electrode is in direct contact with the first semiconductor layer.

13. The display device according to claim 1, further comprising: The second electrode is disposed on the first electrode. The light-emitting element is disposed between the first electrode and the second electrode.

14. The display device according to claim 13, wherein the first electrode comprises at least one of copper and gold.

15. The display device according to claim 1, wherein, The light-emitting element is a miniature light-emitting diode with one side having a length equal to or less than 100 μm.

16. A method for manufacturing a display device, the method comprising: A first electrode is formed on the substrate; A self-assembled monolayer is formed on the first electrode; as well as A micro-light-emitting diode is attached to the self-assembled monolayer, such that the micro-light-emitting diode is in electrical contact with the first electrode via the top surface of the self-assembled monolayer.

17. The method of claim 16, further comprising: A contact electrode is formed on the surface of the micro LED; Attaching the micro LED includes attaching the contact electrode to the self-assembled monolayer to place the contact electrode between the micro LED and the self-assembled monolayer.

18. The method according to claim 16, wherein, Forming the self-assembled monolayer includes: A self-assembled material layer is formed on the first electrode; and the self-assembled material layer is chemically adsorbed onto the surface of the first electrode.

19. The method according to claim 18, wherein, The formation of the self-assembled material layer includes at least one of dip coating, spin coating, slot coating, inkjet printing, and vapor deposition.

20. The method according to claim 19, wherein, The self-assembled material layer comprises at least one of the following: (3-aminopropyl)trimethoxysilane, 11-mercaptoundecanoic acid, (3-trimethoxysilylpropyl)diethylenetriamine, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, perfluorodecyltrichlorosilane, octadecyltrichlorosilane, octadecyltrimethoxysilane, 1-hexadecylthiol, (heptadecylfluoro-1,1,2,2,-tetrahydrodecyl)trichlorosilane, 1H,1H,2H,2H-perfluorodecyltrichlorosilane-perfluorodecyltrichlorosilane, pentafluorobenzenethiol, and dichlorodimethylsilane.

21. The method according to claim 16, in, Forming the self-assembled monolayer includes forming silicon-oxygen bonds with the surface of the first electrode.

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