Display device and method of manufacturing the same

Abstract

A display device and a method for manufacturing the display device are provided. The display device includes a light emitting device having improved reliability while maintaining the liquid repellent property of a peripheral layer after plasma irradiation. The display device includes: a substrate; a pixel electrode disposed on the substrate; a pixel defining layer disposed on the pixel electrode and having an opening that exposes a central portion of the pixel electrode; and a liquid repellent layer disposed on the pixel defining layer and having an upper surface having a concave-convex structure.

Description

[0001] This application claims the benefit of Korean Patent Application No. 10-2019-0061452 filed on May 24, 2019, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0002] The present disclosure relates to a display device and a method of manufacturing the same, and more particularly, to a display device in which reliability of a light emitting device is improved while maintaining liquid repellent properties of a peripheral layer and a method of manufacturing the same. Background Art

[0003] Among various display devices, organic light emitting display devices have attracted attention as next-generation display devices due to their wide viewing angle, high contrast, and fast response speed.

[0004] Generally, in an organic light-emitting display device, a thin film transistor and an organic light-emitting diode are formed on a substrate, and the organic light-emitting diode emits light by itself. The organic light-emitting display device can be used as a display device with a small size (such as a mobile phone), or can be used as a display device with a large size (such as a television).

[0005] An organic light emitting diode (OLED) includes a pixel electrode, a counter electrode, and an organic light emitting layer between the pixel electrode and the counter electrode. The organic light emitting layer of the organic light emitting diode can be formed by various manufacturing processes (eg, chemical vapor deposition (CVD) method, inkjet printing method, etc.). Summary of the invention

[0006] In a display device according to the related art, when an organic light emitting layer is formed by an inkjet printing method, a peripheral layer of a light emitting region may have a liquid repellent property, but the liquid repellent property of the peripheral layer may be deteriorated due to some manufacturing processes.

[0007] One or more embodiments of the present disclosure include a display device having improved reliability of a light emitting device while maintaining the liquid repellent property of a peripheral layer and a method of manufacturing the display device. However, the above technical features are exemplary, and the scope of the present disclosure is not limited thereto.

[0008] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of presented embodiments of the disclosure.

[0009] According to one or more embodiments, a display device includes: a substrate; a pixel electrode disposed on the substrate; a pixel defining layer disposed on the pixel electrode; and a liquid repellent layer disposed on the pixel defining layer. The pixel defining layer has an opening that exposes a central portion of the pixel electrode. The liquid repellent layer has an upper surface with a concave-convex structure.

[0010] The liquid repellent layer may include a first liquid repellent layer and a second liquid repellent layer, wherein the second liquid repellent layer may be positioned on the first liquid repellent layer, the first liquid repellent layer may include a first liquid repellent agent, and the second liquid repellent layer may include a second liquid repellent agent.

[0011] The first liquid repellent agent may have a first surface energy different from a second surface energy of the second liquid repellent agent.

[0012] The first surface energy of the first liquid repellent agent may be greater than the second surface energy of the second liquid repellent agent.

[0013] Each of the first liquid repellent agent and the second liquid repellent agent may have a surface energy of 15 dyne / cm or less, and a first surface energy of the first liquid repellent agent may be 4 to 10 dyne / cm greater than a second surface energy of the second liquid repellent agent.

[0014] The liquid repellent layer may comprise a polymeric material having a molecular weight between 8,000 and 20,000.

[0015] The polymer material may have a main chain and a side chain, and the side chain portion may have a ratio between 20% and 30%.

[0016] The polymeric material may have a glass transition temperature (Tg) of 200°C or less.

[0017] The liquid repellent layer may have a thickness between 30 nm and 70 nm.

[0018] The concavo-convex structure may have a pattern in which convex portions and concave portions are repeatedly arranged, the convex portions may have a first width between 0.01 μm and 3 μm, and the concave portions may have a second width between 0.01 μm and 3 μm.

[0019] An upper surface of the first liquid-repellent layer may have a concavo-convex structure, and a portion of the second liquid-repellent layer may exist on the upper surface of the first liquid-repellent layer.

[0020] According to one or more embodiments, a method for manufacturing a display device is provided, the method comprising: preparing a substrate; forming a pixel electrode on the substrate; forming a pixel defining layer on the pixel electrode; and forming a liquid repellent layer on the pixel defining layer. The pixel defining layer has an opening that exposes a central portion of the pixel electrode. The liquid repellent layer includes an upper surface having a concave-convex structure.

[0021] The step of forming a liquid repellent layer may include: forming an organic material layer including an organic material for forming a pixel defining layer, the organic material being mixed with a first liquid repellent and a second liquid repellent having different surface energies from each other; baking the organic material layer and separating the pixel defining layer, the first liquid repellent and the second liquid repellent so that the first liquid repellent and the second liquid repellent are positioned on the pixel defining layer; irradiating plasma to remove a residual layer of the liquid repellent remaining on the upper surface of the pixel electrode; and baking the pixel defining layer after irradiating the plasma.

[0022] The first surface energy of the first liquid repellent agent may be greater than the second surface energy of the second liquid repellent agent.

[0023] The organic material mixed with the first liquid repellent and the second liquid repellent may include 2 weight percent (wt %) to 5 wt % of the first liquid repellent and 0.5 wt % to 1 wt % of the second liquid repellent.

[0024] In the phase separation step, the second liquid repellent agent may be positioned on the first liquid repellent agent.

[0025] A concavo-convex structure may be formed on the upper surface of the liquid repellent layer by removing at least a portion of the second liquid repellent layer on the pixel defining layer after irradiating the plasma.

[0026] The concavo-convex structure may have a pattern in which convex portions and concave portions are repeatedly arranged, the convex portions may have a first width between 0.01 μm and 3 μm, and the concave portions may have a second width between 0.01 μm and 3 μm.

[0027] Each of the first liquid repellent agent and the second liquid repellent agent may have a surface energy of 15 dyne / cm or less, and a first surface energy of the first liquid repellent agent may be 4 to 10 dyne / cm greater than a second surface energy of the second liquid repellent agent.

[0028] The liquid repellent layer may have a thickness between 30 nm and 70 nm.

[0029] Other aspects, features, and advantages of the present disclosure will become better understood from the accompanying drawings, claims, and detailed description.

[0030] The general and specific aspects of the present disclosure may be implemented using one or more of a system, a method, a computer-readable storage medium, and / or any combination thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0032] Figure 1 is a perspective view of a display device according to an embodiment;

[0033] Figure 2 is an equivalent circuit diagram of a pixel included in a display device according to an embodiment;

[0034] Figure 3 is a cross-sectional view of a display device according to an embodiment;

[0035] FIG. 4A to FIG. 4C is a diagram showing a side chain ratio of a liquid repellent agent in a display device according to an embodiment;

[0036] FIG. 5A to FIG. 5B is a diagram showing a concavo-convex structure formed in the upper surface of a liquid-repellent layer in a display device according to an embodiment;

[0037] Figure 6 is a cross-sectional view of a display device according to an embodiment;

[0038] Figures 7 to 11 are cross-sectional views showing some processes of manufacturing a display device according to an embodiment;

[0039] Fig.12 are cross-sectional views showing some processes in manufacturing a display device according to another embodiment; and

[0040] Fig.13 are cross-sectional views illustrating some processes in manufacturing a display device according to another embodiment. DETAILED DESCRIPTION

[0041] Reference will now be made in detail to exemplary embodiments of the present disclosure, which are shown in the accompanying drawings, wherein the same reference numerals represent the same elements throughout. In this regard, exemplary embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Therefore, exemplary embodiments are described below only with reference to the drawings to explain aspects of this description. As used herein, the term "and / or" includes any combination and all combinations of one or more of the related listed items. When a statement such as "at least one (kind / person) of ... " is located after a column of elements, the column of elements may be modified, and individual elements in the column may not be modified.

[0042] Example embodiments will be described in more detail below with reference to the accompanying drawings. Those components that are the same or corresponding are provided with the same reference numerals regardless of the figure numbers, and redundant explanations are omitted.

[0043] Although terms such as "first", "second", etc. may be used to describe various components, such components are not limited by the above terms. The above terms are only used to distinguish one component from another.

[0044] An expression used in the singular includes the expression in the plural unless it has an obviously different meaning in the context.

[0045] In this specification, it will be understood that the terms "comprises", "has" and "includes" are intended to indicate the presence of the features, quantities, steps, actions, components, parts or combinations thereof disclosed in the specification, but are not intended to exclude the possibility that one or more other features, quantities, steps, actions, components, parts or combinations thereof may exist or may be added.

[0046] It will be understood that when a layer, region or component is referred to as being "formed on" another layer, region or component, the layer, region or component may be directly or indirectly formed on the other layer, region or component. That is, for example, one or more intermediate layers, intermediate regions or intermediate components may exist between them.

[0047] For the convenience of explanation, the sizes of components in the drawings may be exaggerated. In other words, since the sizes and thicknesses of components in the drawings are arbitrarily shown for the convenience of explanation, the embodiments shown in the drawings are not limited thereto.

[0048] When certain embodiments may be implemented differently, the specific process order may be performed differently from the described order. For example, two processes described in succession may be performed substantially simultaneously or in the reverse order of the described order.

[0049] In the specification, the phrase "A and / or B" means A, B, or A and B. In addition, the phrase "at least one of A and B" means A, B, or A and B.

[0050] In the embodiments described below, it will be understood that when layers, regions, elements, etc. are referred to as being "connected", they may be directly connected, or one or more intermediate portions may exist between the layers, regions, or elements. For example, when layers, regions, elements, etc. are referred to as being "electrically connected", they may be directly electrically connected, one or more layers, regions, or elements may be indirectly electrically connected, and / or one or more intermediate portions may exist.

[0051] The x-axis, y-axis, and z-axis are not limited to the three axes of the rectangular coordinate system and can be interpreted in a broader sense. For example, the x-axis, y-axis, and z-axis can be perpendicular to each other, or can represent different directions that are not perpendicular to each other.

[0052] Hereinafter, the display device 1 according to the embodiment is described as an organic light-emitting display device as an example, but the display device 1 of the present disclosure is not limited thereto. In the embodiment, the display device 1 may include an inorganic light-emitting display, an inorganic electroluminescent (EL) display device, or a quantum dot light-emitting display device. For example, the light-emitting layer of the display element included in the display device 1 may include an organic material, a quantum dot, or an organic material and a quantum dot.

[0053] Figure 1 is a perspective view of a display device 1 according to the embodiment.

[0054] Reference Figure 1 The display device 1 includes a display area DA that displays an image and a non-display area NDA that does not display an image. The display device 1 may provide an image by using light emitted from a plurality of pixels P arranged in the display area DA.

[0055] exist Figure 1 In the embodiment, the display area DA of the display device 1 has a square shape, but the present disclosure is not limited thereto. The display area DA may have a circular shape, an elliptical shape, or a polygonal shape such as a triangle, a pentagon, etc. In addition, Figure 1 The display device 1 is shown as including a flat panel, but without departing from the scope of the present disclosure, the display device 1 may be implemented in various types, for example, a flexible display device, a foldable display device, a rollable display device, etc.

[0056] Figure 2 : is an equivalent circuit diagram of a pixel P included in the display device 1 of the embodiment.

[0057] Reference Figure 2 , the pixel P includes a pixel circuit PC connected to the scan line SL and the data line DL and an organic light emitting diode OLED connected to the pixel circuit PC.

[0058] The pixel circuit PC includes a driving thin film transistor Td, a switching thin film transistor Ts and a storage capacitor Cst. The switching thin film transistor Ts is connected to the scan line SL and the data line DL, and transmits a data signal Dm input through the data line DL to the driving thin film transistor Td according to a scan signal Sn input through the scan line SL.

[0059] The storage capacitor Cst is connected to the switching thin film transistor Ts and the driving voltage line PL, and stores a charge amount corresponding to a voltage difference between a voltage transmitted from the switching thin film transistor Ts and a first power source voltage ELVDD (or driving voltage) input through the driving voltage line PL.

[0060] The driving thin film transistor Td is connected to the driving voltage line PL and the storage capacitor Cst, and can control the driving current flowing from the driving voltage line PL to the organic light emitting diode OLED in response to the voltage value stored in the storage capacitor Cst. The organic light emitting diode OLED can emit light with a predetermined brightness according to the driving current.

[0061] Figure 2 An example is shown in which the pixel circuit PC includes two thin film transistors and one storage capacitor, but the present disclosure is not limited thereto. In an embodiment, the pixel circuit PC may include seven thin film transistors and one storage capacitor. In another embodiment, the pixel circuit PC may include two or more storage capacitors.

[0062] Figure 3 is a cross-sectional view of a display device 1 according to the embodiment.

[0063] Reference Figure 3 According to the embodiment, the display device 1 includes a substrate 100, a pixel electrode 180 disposed on the substrate 100, a pixel defining layer 191 disposed on the pixel electrode 180, and a liquid repellent layer 192 disposed on the pixel defining layer 191, wherein the pixel defining layer 191 has an opening that exposes the central portion of the pixel electrode 180, and wherein the liquid repellent layer 192 has an upper surface with a concave-convex structure.

[0064] The substrate 100 may include glass or a polymer resin. The polymer resin may be a transparent polymer resin including at least one of polyethersulfone (PES), polyacrylate (PA), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate (PAR), polyimide (PI), polycarbonate (PC), and cellulose acetate propionate (CAP). The substrate 100 including the polymer resin may be flexible, rollable, or bendable. The substrate 100 may have a multilayer structure (not shown) including a layer including a polymer resin and an inorganic layer.

[0065] The buffer layer 110 is disposed on the substrate 100 and planarizes the upper surface of the substrate 100 while preventing impurities from penetrating from the substrate 100. The buffer layer 110 may include silicon oxide (SiO x ), Silicon Nitride (SiN x ) and silicon oxynitride (SiO x N y ) at least one of.

[0066] The active layer 120 is disposed on the buffer layer 110. The active layer 120 may include an oxide semiconductor and / or a silicon semiconductor. When the active layer 120 includes an oxide semiconductor, the active layer 120 may include an oxide of a material including but not limited to indium (In), gallium (Ga), tin (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), titanium (Ti) and zinc (Zn). For example, the active layer 120 may include an indium tin zinc oxide (InSnZnO, ITZO) active layer, an indium gallium zinc oxide (InGaZnO, IGZO) active layer, etc. When the active layer 120 includes a silicon semiconductor, the active layer 120 may include amorphous silicon (a-Si) or low temperature polycrystalline silicon (LTPS).

[0067] The first insulating layer 130 is disposed on the buffer layer 110, covering the active layer 120. The gate electrode 140 is disposed on the first insulating layer 130, overlapping at least a portion of the active layer 120. For example, the gate electrode 140 may have a single-layer or multi-layer structure including one or more metals selected from aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W) and copper (Cu). The gate electrode 140 may be connected to a gate line (not shown) that provides an electrical signal to the gate electrode 140.

[0068] The second insulating layer 150 is disposed on the first insulating layer 130, covering the gate electrode 140. The source electrode 160 and / or the drain electrode 161 are disposed on the second insulating layer 150. The source electrode 160 and / or the drain electrode 161 may be electrically connected to the active layer 120 via corresponding contact holes formed in the second insulating layer 150 and the first insulating layer 130.

[0069] The third insulating layer 170 is disposed on the second insulating layer 150. Figure 3 In the embodiment, the third insulating layer 170 is shown as having a single-layer structure, but in other embodiments, the third insulating layer 170 may have a multi-layer structure. The third insulating layer 170 flattens the upper surface of the pixel circuit PC, thereby flattening the surface on which the organic light emitting diode OLED is to be formed.

[0070] The third insulating layer 170 may include conventional general polymers, polymer derivatives having phenol groups, acryl polymers, imide polymers, aryl ether polymers, amide polymers, fluoride polymers, paraxylene polymers, vinyl alcohol polymers and / or blends thereof, and conventional general polymers include but are not limited to benzocyclobutene (BCB), polyimide, hexamethyldisiloxane (HMDSO), polymethyl methacrylate (PMMA) and polystyrene (PS). In an embodiment, the third insulating layer 170 may include organic materials and inorganic materials.

[0071] The pixel electrode 180 is disposed on the third insulating layer 170. The pixel electrode 180 may be a (semi-) transmissive electrode or a reflective electrode. The pixel electrode 180 may be electrically connected to the pixel circuit PC (eg, the drain electrode 161) via a contact hole formed in the third insulating layer 170.

[0072] In an embodiment, the pixel electrode 180 may include a reflective layer and a transparent electrode layer or a semi-transparent electrode layer disposed on the reflective layer, and the reflective layer may include but is not limited to Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr and a mixture thereof. The transparent electrode layer or the semi-transparent electrode layer may include but is not limited to indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In 2 O 3 ), indium gallium oxide, and aluminum zinc oxide (AZO). For example, the pixel electrode 180 may include a stack structure including ITO / Ag / ITO.

[0073] The pixel defining layer 191 is disposed on the pixel electrode 180. The pixel defining layer 191 has an opening corresponding to the light emitting area AA to define the light emitting area of ​​the pixel P, and the opening exposes the central portion of the pixel electrode 180. In addition, the pixel defining layer 191 increases the distance between the edge of the pixel electrode 180 and the counter electrode 210 located on the pixel electrode 180, thereby preventing an arc from being generated at the edge of the pixel electrode 180. The pixel defining layer 191 may include an organic insulating material such as polyimide, polyamide, acrylic resin, benzocyclobutene (BCB), hexamethyldisiloxane (HMDSO), and phenolic resin, and may be obtained by spin coating.

[0074] The liquid repellent layer 192 having a concavo-convex structure on the upper surface is disposed on the pixel defining layer 191. The liquid repellent layer 192 can impart liquid repellent properties to the non-luminous area NAA so that the luminescent material is applied to the luminous area AA but not to the non-luminous area NAA during a manufacturing process (e.g., an inkjet printing process).

[0075] Reference Figure 6 and Fig. 9 , the liquid repellent layer 192 may include a first liquid repellent layer 193 including a first liquid repellent and a second liquid repellent layer 194 including a second liquid repellent disposed on the first liquid repellent layer 193. Here, the first liquid repellent included in the first liquid repellent layer 193 and the second liquid repellent included in the second liquid repellent layer 194 have different surface energies from each other, and the surface energy of the first liquid repellent may be greater than the surface energy of the second liquid repellent. For example, 2 weight percent (wt%) to 5 wt% of the first liquid repellent having a relatively high surface energy may be included relative to the organic material, and 0.5 wt% to 1 wt% of the second liquid repellent may be included relative to the organic material.

[0076] The first liquid repellent of the first liquid repellent layer 193 and the second liquid repellent of the second liquid repellent layer 194 may both have a surface energy of 15 dyne / cm or less, and the surface energy of the first liquid repellent may be 4 to 10 dyne / cm greater than that of the second liquid repellent.

[0077] The liquid repellent (e.g., the first liquid repellent and the second liquid repellent) included in the liquid repellent layer 192 may include a polymer material in which a fluorine compound is fixed in an organic material (such as polyimide). The polymer material may have a main chain and a side chain, and may have a molecular weight of 8000 to 20000. The polymer material may have a side chain ratio of 20% to 30%, thereby reducing its glass transition temperature (Tg) to 200°C or less while increasing mobility at high temperatures, so that the liquid repellent can be positioned above the pixel defining layer 191. Therefore, during the baking process, the liquid repellent can be easily positioned above the pixel defining layer 191.

[0078] Generally, the glass transition temperature (Tg) can be adjusted via the crosslinking density between the resin and the liquid repellent in the photoresist layer (not shown), and in order to lower the glass transition temperature (Tg), the side chain ratio can be reduced to reduce the crosslinking density between the resin and the liquid repellent in the photoresist layer.

[0079] FIG. 4A to FIG. 4C : is a graph showing the side chain ratio of the liquid repellent agent in the display device 1 according to the embodiment.

[0080] exist Figure 4A In , only one of the four side chains has an acrylate reactant, so 25% of the side chains can be obtained. Figure 4B In the present invention, when the acrylate precursor reacts with the hydroxyl group (-OH), 25% or less of the side chains can be obtained when the amount of the acrylate precursor is limited to 50% or less of the -OH sites, and 12.5% ​​or less of the side chains can be obtained when the amount of the acrylate precursor is limited to 25% or less of the -OH sites. Figure 4CIn the invention, the side chain ratio can be adjusted via the ratio between m and n. For example, when m and n have a ratio of 1:2 or more, 16.5% or more of side chains can be obtained.

[0081] According to the display device 1 of the embodiment, by using Figure 4A , Figure 4B and Figure 4C A combination of at least one of the following can be used to obtain 20% to 30% of the side chains of the liquid repellent, and the glass transition temperature (Tg) of the polymer material can be reduced to 200° C. or lower, so the liquid repellent can be easily positioned above the pixel defining layer 191 during the baking process.

[0082] Due to the difference between the surface energy of the first liquid repellent of the first liquid repellent layer 193 and the surface energy of the second liquid repellent of the second liquid repellent layer 194, the second liquid repellent can be positioned on the first liquid repellent due to vertical separation. In addition, due to the Marangoni effect, lateral separation can occur partially (or locally) between the first liquid repellent and the second liquid repellent.

[0083] When the pixel defining layer 191 and the liquid repellent layer 192 are formed, the liquid repellent residual layer 181 (see Figure 7 ) will be located on the upper surface of the pixel electrode 180. The residual layer 181 remaining on the upper surface of the pixel electrode 180 will affect the luminous efficiency and life of the organic light emitting diode OLED including an electron transport layer (ETL), a hole transport layer (HTL) and an emission layer (EML) formed between the pixel electrode 180 and the counter electrode 210. Therefore, the residual layer 181 having liquid repellent properties and remaining on the upper surface of the pixel electrode 180 can be removed by irradiating plasma thereto during the plasma cleaning process. However, the liquid repellent layer 192 formed on the pixel defining layer 191 will also be removed by plasma, and therefore, the liquid repellent properties will deteriorate.

[0084] In the display device 1 according to the embodiment, the second liquid repellent of the second liquid repellent layer 194 is used as a sacrificial layer. Therefore, even after the plasma cleaning process for removing the residual layer 181 from the upper surface of the pixel electrode 180, the liquid repellent layer 192 remains intact. Figure 3 As shown in FIG. 1 , the liquid-repellent layer 192 remains on the pixel-defining layer 191 , and due to the liquid-repellent layer 192 remaining on the pixel-defining layer 191 , the liquid-repellent property may be maintained or improved.

[0085] Figure 5A and Figure 5B 1 is a diagram showing a concavo-convex structure formed in the upper surface of the liquid-repellent layer 192 in the display device 1 according to the embodiment.

[0086] Reference Figure 5A and Figure 5B, because lateral separation may partially occur on the liquid repellent layer 192 due to the Marangoni effect, the second liquid repellent on the pixel defining layer 191 is at least partially removed in the plasma cleaning process for removing the residual layer 181 on the pixel electrode 180, and therefore, a concavo-convex structure may be formed in the upper surface of the first liquid repellent layer 193. The concavo-convex structure in the upper surface of the first liquid repellent layer 193 has a pattern in which convex portions and concave portions are repeatedly arranged. The convex portion may have a width of 0.01 μm to 3 μm, and the concave portion may have a width of 0.01 μm to 3 μm. Because the concavo-convex structure is formed in the upper surface of the liquid repellent layer 192, the surface roughness may be increased to a range between 10 nm and 25 nm, and due to the liquid repellent layer 192 retained on the pixel defining layer 191, the liquid repellent properties may be maintained or improved.

[0087] Figure 6 is a cross-sectional view of a display device 1 according to the embodiment.

[0088] Reference Figure 3 and Figure 6 After plasma cleaning is performed to remove the residual layer 181 remaining on the pixel electrode 180, as shown in FIG. Figure 3 As shown in , the second liquid repellent of the second liquid repellent layer 194 may be completely removed and only the first liquid repellent may remain in the liquid repellent layer 192, or as shown in Figure 6 As shown in , the second liquid repellent agent may partially remain on the first liquid repellent layer 193 .

[0089] The liquid repellent layer 192 remaining on the pixel defining layer 191 may have a thickness of about 30 nm to about 70 nm.

[0090] The intermediate layer 200 is disposed on a portion of the pixel electrode 180 exposed via the pixel defining layer 191. The intermediate layer 200 may include an organic light emitting layer, and one or more functional layers such as a hole transport layer (HTL), a hole injection layer (HIL), an electron transport layer (ETL), and an electron injection layer (EIL) may be selectively disposed under the organic light emitting layer and over the organic light emitting layer.

[0091] The organic light emitting layer may include an organic material including, but not limited to, a fluorescent material or a phosphor material emitting red, green, blue or white light. The organic light emitting layer may include a low molecular weight organic material or a polymeric material.

[0092] According to one embodiment, a plurality of pixel electrodes 180 are provided, and the intermediate layer 200 may correspond to each of the plurality of pixel electrodes 180. However, the present disclosure is not limited thereto. The intermediate layer 200 may be variously modified without departing from the scope of the present disclosure. For example, the intermediate layer 200 may be arranged throughout the plurality of pixel electrodes 180. In an embodiment, the organic light emitting layer may correspond to each of the plurality of pixel electrodes 180, and one or more functional layers other than the organic light emitting layer may be arranged integrally throughout the plurality of pixel electrodes 180.

[0093] like Figure 6 As shown in , the counter electrode 210 is disposed on the intermediate layer 200 and may extend to cover the liquid repellent layer 192. The counter electrode 210 may be a transmissive electrode or a reflective electrode. In an embodiment, the counter electrode 210 may be a transparent electrode or a semi-transparent electrode and may be configured to include a metal thin film of at least one of Li, Ca, LiF / Ca, LiF / Al, Al, Ag, Mg and compounds thereof having a small work function.

[0094] In alternative embodiments, such as ITO, IZO, ZnO or In 2 O 3 A transparent conductive oxide (TCO) of may be further disposed on the counter electrode 210. The counter electrode 210 may be disposed throughout the display area DA and the non-display area NDA, overlapping the intermediate layer 200 and the pixel defining layer 191. The counter electrode 210 may be integrally disposed with respect to the plurality of organic light emitting diodes OLED, and may correspond to the plurality of pixel electrodes 180.

[0095] When the pixel electrode 180 is a reflective electrode and the opposite electrode 210 is a transmissive electrode, light emitted from the intermediate layer 200 is emitted toward the opposite electrode 210. In this case, the display device 1 may be a top emission type.

[0096] In an embodiment, when the pixel electrode 180 is a transparent electrode or a semi-transparent electrode and the counter electrode 210 is a reflective electrode, light emitted from the intermediate layer 200 is released toward the substrate 100. In this case, the display device 1 may be a bottom emission type. However, the present disclosure is not limited thereto, that is, the display device 1 according to the embodiment may be a dual emission type that emits light toward both the front surface and the rear surface.

[0097] Figures 7 to 11 are cross-sectional views showing some processes of manufacturing the display device 1 according to the embodiment. Fig.12 are cross-sectional views illustrating some processes of manufacturing the display device 1 according to another embodiment. Fig.13 are cross-sectional views illustrating some processes of manufacturing the display device 1 according to another embodiment.

[0098] In the following, reference will be made to Figures 7 to 13 The method of manufacturing the display device 1 is described in the order of processes.

[0099] Reference Figures 7 to 11 , the method for manufacturing the display device 1 according to the embodiment may include the following steps: preparing a substrate 100; forming a pixel electrode 180 on the substrate 100; forming a pixel defining layer 191 having an opening exposing a central portion of the pixel electrode 180 on the pixel electrode 180; and forming a liquid repellent layer 192 on the pixel defining layer 191. The liquid repellent layer 192 has a concavo-convex structure on its upper surface.

[0100] The substrate composition for forming the substrate 100 may be applied to a carrier substrate (not shown). The carrier substrate may be separated from the substrate 100 after all elements in the display device 1 are stacked.

[0101] The substrate composition may include a precursor composition solution of polyethersulfone (PES), polyacrylate (PA), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate (PAR), polyimide (PI), polycarbonate (PC), cellulose acetate propionate (CAP), etc.

[0102] In the step of preparing the substrate 100, a substrate composition may be applied to a carrier substrate and cured to form the substrate 100. For example, a polyamic acid composition solution may be cured to form a polyimide (PI) substrate.

[0103] Reference Figure 7 A buffer layer 110, an active layer 120, a first insulating layer 130, a gate electrode 140, a second insulating layer 150, a source electrode 160, a drain electrode 161, a third insulating layer 170, a pixel electrode 180, and a pixel defining layer 191 having an opening exposing a central portion of the pixel electrode 180 may be formed on the substrate 100 (see Figure 8 The above processes may be performed by one or more photolithography processes known in the art, and thus, their detailed descriptions are omitted.

[0104] After forming the pixel defining layer 191, a liquid repellent layer 192 may be formed on the pixel defining layer 191. The liquid repellent layer 192 has an upper surface with a concavo-convex structure. The liquid repellent layer 192 may impart liquid repellent properties to the non-luminous area NAA so that the luminescent material is not applied to the non-luminous area NAA during the inkjet printing process.

[0105] The step of forming the liquid repellent layer 192 may include: mixing the organic material of the pixel defining layer 191 with the first liquid repellent and the second liquid repellent, wherein the first liquid repellent and the second liquid repellent may have different surface energies; phase-separating the pixel defining layer 191 from the first liquid repellent and the second liquid repellent so that the first liquid repellent and the second liquid repellent are formed above the pixel defining layer 191; irradiating plasma to remove the liquid repellent residual layer 181 from the upper surface of the pixel electrode 180; and baking the pixel defining layer 191 after the plasma cleaning process.

[0106] Return to reference Figure 7 , an organic material layer 190 may be provided on the pixel electrode 180 by using a mixture of an organic material for forming a pixel defining layer 191 and a first liquid repellent and a second liquid repellent having surface energies different from each other. The organic material layer 190 is a layer in which a photoresist material, an organic material, a first liquid repellent and a second liquid repellent are mixed, and may serve as the pixel defining layer 191 defining a pixel area.

[0107] The surface energy of the first liquid repellent may be greater than the surface energy of the second liquid repellent between the first liquid repellent and the second liquid repellent mixed with the organic material for forming the pixel defining layer 191. In one embodiment, 2 wt % to 5 wt % of the first liquid repellent having a relatively high surface energy may be included relative to the organic material, and 0.5 wt % to 1 wt % of the second liquid repellent having a relatively low surface energy may be included relative to the organic material.

[0108] The first liquid repellent of the first liquid repellent layer 193 and the second liquid repellent of the second liquid repellent layer 194 may both have a surface energy of 15 dyne / cm or less, and the surface energy of the first liquid repellent may be 4 to 10 dyne / cm greater than that of the second liquid repellent.

[0109] The liquid repellent layer 192 may include a polymer material in which a fluorine compound is fixed in an organic material such as polyimide. The polymer material may have a main chain and a side chain, and may have a molecular weight of 8000 to 20000. The polymer material may have a side chain ratio of 20% to 30%, thereby reducing its glass transition temperature (Tg) to 200°C or less while increasing mobility at high temperatures, so that the liquid repellent can be positioned above the pixel defining layer 191. Therefore, during the baking process, the liquid repellent can be easily positioned above the pixel defining layer 191.

[0110] After the organic material for forming the pixel defining layer 191 is mixed with the first liquid repellent and the second liquid repellent, the organic material layer 190 is baked to separate the pixel defining layer 191 , the first liquid repellent and the second liquid repellent, thereby allowing the first liquid repellent and the second liquid repellent to move upward onto the pixel defining layer 191 .

[0111] Reference Figure 8 In the phase separation process, the organic material layer 190 is baked so that the first liquid repellent and the second liquid repellent can be moved onto the pixel defining layer 191, and the second liquid repellent having a relatively low surface energy can be moved onto the first liquid repellent, so that the first liquid repellent layer 193 including the first liquid repellent and the second liquid repellent layer 194 including the second liquid repellent can be vertically separated from each other.

[0112] Furthermore, in the phase separation process, since the surface energy of the first liquid repellent agent is greater than that of the second liquid repellent agent, the second liquid repellent agent moves onto the first liquid repellent agent (vertical separation) and partially undergoes lateral separation due to the Marangoni effect. Fig. 9 Shows Figure 8 192. Due to the vertical separation and the lateral separation, the liquid repellent layer 192 may have a concavo-convex structure in the boundary surface between the first liquid repellent layer 193 including the first liquid repellent agent and the second liquid repellent layer 194 including the second liquid repellent agent. The concavo-convex structure formed in the boundary surface between the first liquid repellent layer 193 and the second liquid repellent layer 194 may have a pattern including convex portions 195 and concave portions 196 that are repeatedly arranged. The width W of the convex portion 195 is 1 The width W of the concave portion 196 may be about 0.01 μm to about 3 μm. 2 It may be about 0.01 μm to about 3 μm.

[0113] Reference Fig.10 , when the pixel defining layer 191 and the liquid repellent layer 192 are formed, a residual layer 181 will remain on the upper surface of the pixel electrode 180. The residual layer 181 remaining on the upper surface of the pixel electrode 180 will affect the luminous efficiency and life of the organic light emitting diode OLED including an electron transport layer (ETL), a hole transport layer (HTL) and an emission layer (EML) formed between the pixel electrode 180 and the counter electrode 210. Therefore, the residual layer 181 remaining on the upper surface of the pixel electrode 180 can be removed by irradiating plasma P to it during the plasma cleaning process. However, the liquid repellent layer 192 formed on the pixel defining layer 191 is also removed by the plasma P used to remove the residual layer 181 from the upper surface of the pixel electrode 180, and therefore, the liquid repellent properties are deteriorated.

[0114] In the display device 1 according to the embodiment, the second liquid repellent is used as a sacrificial layer. Therefore, even after the plasma cleaning process for removing the residual layer 181 from the upper surface of the pixel electrode 180, the liquid repellent layer 192 remains on the pixel defining layer 191, and due to the liquid repellent layer 192 remaining on the pixel defining layer 191, the liquid repellent property can be maintained.

[0115] Reference Figure 5A and Figure 5B , because lateral separation may partially occur on the liquid repellent layer 192 due to the Marangoni effect, and the second liquid repellent on the pixel defining layer 191 is at least partially removed in the plasma cleaning process for removing the residual layer 181 from the upper surface of the pixel electrode 180, and therefore, a concavo-convex structure may be formed in the upper surface of the first liquid repellent layer 193. The concavo-convex structure in the upper surface of the first liquid repellent layer 193 has a pattern in which convex portions and concave portions are repeatedly arranged. The convex portion may have a width of 0.01 μm to 3 μm, and the concave portion may have a width of 0.01 μm to 3 μm. Because the concavo-convex structure is formed in the upper surface of the liquid repellent layer 192, the surface roughness may be increased to a range between 10 nm and 25 nm, and the liquid repellent properties may be maintained or improved due to the liquid repellent layer 192 remaining on the pixel defining layer 191.

[0116] Reference Figures 11 to 13 , depending on the degree of removal of the second liquid repellent agent on the pixel defining layer 191 , the concavo-convex structure may be obtained differently. Fig.11 It is shown that the concavo-convex structure may have only the first liquid-repellent layer 193 . Fig.12 It is shown that the concavo-convex structure can be obtained by disposing the second liquid-repellent layer 194 on the first liquid-repellent layer 193. Optionally, Fig.13 It is shown that the concavo-convex structure may include the second liquid-repellent layer 194 partially remaining on the first liquid-repellent layer 193 .

[0117] Even after plasma is irradiated to remove the residual layer 181 from the upper surface of the pixel electrode 180, the residual layer 181 may partially remain on the upper surface of the pixel electrode 180. In this case, a baking process may be additionally performed to remove impurities remaining on the pixel electrode 180. In addition, the liquid repellent present in the pixel defining layer 191 may be additionally moved upward by the baking process, and thus, the liquid repellent layer 192 may be formed as shown in FIG. Fig.12 The thickness t shown in FIG. 5 is about 30 nm to about 70 nm.

[0118] Reference Figure 3 and Figure 6 The intermediate layer 200 including the organic light emitting layer may be disposed on the portion of the pixel electrode 180 exposed via the pixel defining layer 191, and the counter electrode 210 may be disposed on the intermediate layer 200. Unlike the pixel electrode 180, the counter electrode 210 may be integrally disposed throughout the plurality of pixels P.

[0119] According to an embodiment, the counter electrode 210 may include a low reflective layer. Since the counter electrode 210 is arranged in the emission area AA and the non-emission area NAA, the counter electrode 210 may reduce light reflectivity from the emission area AA, thereby reducing the total light reflectivity of the display device 1.

[0120] A thin film encapsulation layer (not shown) may be disposed on the counter electrode 210. The thin film encapsulation layer may include at least one organic layer and at least one inorganic layer. In the top emission type display device 1 according to an embodiment of the present disclosure, the thin film encapsulation layer may be disposed on the organic light emitting diode OLED, and light emitted from the organic light emitting diode OLED may be visible from the outside through the thin film encapsulation layer.

[0121] According to the prior art, the liquid repellent property of the peripheral layer may be degraded due to some manufacturing processes used to form the display device. According to an embodiment, the liquid repellent layer 192 may include a first liquid repellent and a second liquid repellent having different surface energies from each other, and thus, the display device 1 may have improved reliability of the organic light emitting diode OLED while maintaining the liquid repellent property of the peripheral layer (e.g., the pixel defining layer 191).

[0122] According to the embodiment, a display device having improved reliability of a light emitting device (eg, an organic light emitting diode) while maintaining the liquid repellent property of the peripheral layer and a method for manufacturing the same may be provided. However, the scope of the present disclosure is not limited to the above effects.

[0123] It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. The description of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments. Although one or more exemplary embodiments have been described with reference to the drawings, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the claims.

Claims

1. A display device, comprising: substrate; A pixel electrode, disposed on the substrate; a pixel defining layer, disposed on the pixel electrode, the pixel defining layer having an opening for exposing a central portion of the pixel electrode; as well as a liquid-repellent layer, disposed on the pixel defining layer, the liquid-repellent layer comprising an upper surface having a concave-convex structure, The liquid repellent layer includes a first liquid repellent layer and a second liquid repellent layer, wherein the second liquid repellent layer is positioned on the first liquid repellent layer, the first liquid repellent layer includes a first liquid repellent, and the second liquid repellent layer includes a second liquid repellent used as a sacrificial layer.

2. The display device according to claim 1, wherein: The first liquid repellent agent has a first surface energy different from a second surface energy of the second liquid repellent agent.

3. The display device according to claim 1, wherein: The first surface energy of the first liquid repellent agent is greater than the second surface energy of the second liquid repellent agent.

4. The display device according to claim 1, wherein: Each of the first liquid repellent and the second liquid repellent has a surface energy of 15 dyne / cm or less, and a first surface energy of the first liquid repellent is 4 to 10 dyne / cm greater than a second surface energy of the second liquid repellent.

5. A method for manufacturing a display device, the method comprising: preparing a substrate; forming a pixel electrode on the substrate; forming a pixel defining layer on the pixel electrode, the pixel defining layer having an opening exposing a central portion of the pixel electrode; as well as forming a liquid-repellent layer on the pixel defining layer, wherein the liquid-repellent layer comprises an upper surface having a concave-convex structure, Wherein, the step of forming the liquid repellent layer comprises: forming an organic material layer including an organic material for forming the pixel defining layer, the organic material being mixed with a first liquid repellent and a second liquid repellent having different surface energies from each other, the second liquid repellent being used as a sacrificial layer; baking the organic material layer and separating the pixel defining layer, the first liquid repellent agent, and the second liquid repellent agent so that the first liquid repellent agent and the second liquid repellent agent are positioned on the pixel defining layer; irradiating plasma to remove a residual layer of liquid repellent remaining on an upper surface of the pixel electrode; and The pixel defining layer is baked after the plasma is irradiated.

6. The method according to claim 5, wherein: The first surface energy of the first liquid repellent agent is greater than the second surface energy of the second liquid repellent agent.

7. The method according to claim 5, wherein: The organic material mixed with the first liquid repellent and the second liquid repellent includes 2 wt % to 5 wt % of the first liquid repellent and 0.5 wt % to 1 wt % of the second liquid repellent.

8. The method according to claim 5, wherein: In the phase separation step, the second liquid repellent agent is positioned on the first liquid repellent agent.

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