FLEXIBLE DISPLAY DEVICE AND METHOD FOR MANUFACTURING THE SAME

Abstract

A flexible display device comprising: a substrate (110) over which a thin-film transistor (130) is arranged; an intermediate layer (150) arranged to cover the thin film transistor (130); a first electrode (181) disposed on the intermediate layer (150) and connected to the thin film transistor (130); a dam (160) disposed on the intermediate layer (150) and the first electrode (181) and defining a first region exposing a portion of the intermediate layer (150), a second region exposing a portion of the first electrode (181), and a third region outside the first region and the second region; a first structure (170) arranged in the first region defined by the dam (160) and having an inverted conical shape toward the substrate (110); an organic light-emitting layer (182) disposed on the first electrode (181) exposed in the second region; a second electrode (183) disposed on the organic light-emitting layer (182); and a second structure (175) arranged on the dam (160) in the third region, wherein the second structure (175) is conically shaped towards the substrate (110), wherein the first structure (170) is arranged to contact the intermediate layer (150) and both side surfaces of the first structure (170) contact the dam (160).

Description

BACKGROUNDArea of Revelation

[0001] The present disclosure relates to flexible display devices and methods of manufacturing the same, and more particularly relates to a flexible display device for minimizing a peeling defect of an organic light-emitting layer by having a structure with an inverted conical shape and a method of manufacturing the same. Description of the background

[0002] Image display devices configured to display various information or data on a display screen serve as a core device in the information and communication age. Display devices are becoming thinner and lighter and are being developed to have high performance while being portable. Among various types of display devices, there is a growing demand for display devices that can be manufactured to be relatively lightweight and thin in package. Display devices having a self-emissive property are advantageous in terms of lower power consumption because low-voltage driving is available, and they have a short response time, high luminous efficiency, a wide viewing angle, and a high contrast ratio.Thus, these display devices have been developed as next-generation displays. These display devices can display images by stimulating a plurality of subpixels arranged in a matrix. Each of the plurality of subpixels includes a light-emitting element and a plurality of transistors that independently drive the light-emitting element.

[0003] A liquid crystal display (LCD), a quantum dot (QD), a field emission display (FED), an organic light-emitting diode (OLED), and the like are examples of such display devices. Among these display devices, the organic light-emitting display has become attractive for displaying more vivid colors and implementing a more compact package without requiring a separate light source. Using a self-emitting organic light-emitting diode (OLED), it has advantages of fast response time, high contrast ratio, high luminous efficiency, high luminance, wide viewing angle, and the like.

[0004] Recently, a flexible display device that can display images even when the display device is bent like a paper by arranging a display portion and wiring on a flexible substrate such as a plastic substrate has been attracting attention as a next-generation display device.

[0005] As the application range of flexible display devices expands from computer monitors and TVs to portable electronic devices with displays such as mobile phones, tablet computers, laptop computers, and the like, research and development on flexible display devices with reduced volume and weight while having a large display area is underway.

[0006] In particular, as described above, the organic light-emitting diode (OLED) display device does not require a separate light source; therefore, this type of display device can be implemented to have a relatively thin package. As a result, increasing attempts have been made to develop the organic light-emitting display device as a flexible display device.

[0007] In a situation where a flexible organic light-emitting display device is folded, tensile stress and compressive stress may be applied to the flexible organic light-emitting display device due to the folding.

[0008] The continuous application of tensile stress and compressive stress due to repeated folding may cause a peeling defect in which multilayers in the organic light-emitting display device are separated from each other, and this may adversely affect the reliability of the flexible organic light-emitting display device.

[0009] In particular, an organic light-emitting layer among the multiple layers included in the organic light-emitting display device is the most sensitive part due to the difficulty of implementing patterning for mitigating folding stress and relatively weak adhesion.

[0010] In order to solve such a peeling problem in an organic light-emitting layer of the flexible organic light-emitting display device, various attempts have been made, such as depositing a spacer on a dam layer.

[0011] US 2016 / 0 064 461 A1 describes a flexible organic light-emitting diode display panel comprising a substrate in which an opening region and a non-opening region are defined; a light-emitting diode disposed on the substrate; a dam layer disposed in the non-opening region; and a delamination reducing layer disposed in the non-opening region and having a reversely tapered shape.

[0012] US 2019 / 0081117 A1 describes a luminescent display panel comprising a first electrode positioned on a substrate, a dam overlapping at least a portion of the first electrode, a first body positioned on the dam, a second body positioned on the first body, a first organic layer positioned on the substrate and overlapping the first electrode and the dam, and a second electrode positioned on the substrate and overlapping the first electrode, the dam, and the first organic layer, wherein the first body has a positive side slope and the second body has a negative side slope. SUMMARY

[0013] To address the above-mentioned problems, embodiments described herein relate to a flexible display device and its manufacturing method for eliminating peeling defects in an organic light-emitting layer. According to one aspect of the present disclosure, a flexible display device is provided according to claim 1. According to another aspect of the present disclosure, a method for manufacturing a flexible display device is provided according to claim 6. Further embodiments are described in the dependent claims.

[0014] In accordance with one aspect of the present disclosure, a flexible display device is provided, comprising a substrate over which a thin-film transistor is disposed, an intermediate layer disposed so as to cover the thin-film transistor, a first electrode disposed on the intermediate layer and connected to the thin-film transistor, a dam disposed on the intermediate layer and the first electrode and defining a first region exposing a part of the intermediate layer, a second region exposing a part of the first electrode, and a third region excluding the first region and the second region, a first structure disposed in the first region defined by the dam and having an inverted conical shape toward the substrate, an organic light-emitting layer disposed on the first electrode exposed in the second region,a second electrode disposed on the organic light-emitting layer and a second structure disposed on the dam in the third region, the second structure being conically shaped toward the substrate. The first structure is disposed such that it touches the intermediate layer and both side surfaces of the first structure touch the dam.

[0015] In accordance with another aspect of the present disclosure, there is provided a method of manufacturing the flexible display device, comprising a step of disposing an intermediate layer for covering a thin-film transistor over a substrate over which the thin-film transistor is disposed, a step of disposing a first electrode electrically connected to the thin-film transistor on the intermediate layer, a step of disposing, on the intermediate layer, a first pattern such that it is spaced apart from the first electrode and is invertedly conical in shape toward the substrate, a step of disposing a dam on the intermediate layer and the first electrode, a step of disposing an organic light-emitting layer on the first electrode, a step of disposing a second electrode such thatthat it overlaps all or at least part of the substrate, on the organic light-emitting layer, and a step of arranging a second structure, which is conically shaped toward the substrate, on the dam. The dam is arranged such that it touches both side surfaces of the first structure.

[0016] In accordance with the aspects described above, further aspects, embodiments and examples of the present disclosure and advantages resulting therefrom will be described below, and modifications thereof will become apparent to those skilled in the art from the following detailed description.

[0017] In accordance with aspects of the present disclosure, since an inverted conical-shaped structure for preventing lateral current leakage between adjacent pixels or subpixels through an organic light-emitting layer can be arranged to be adjacent to a conical-shaped structure, it is indeed possible to improve a degree of freedom in designing a corresponding flexible display device, and an advantage of implementing a thin flexible display device is provided because there is no increase in thickness that would be caused by forming a structure with an inverted conical shape.

[0018] Furthermore, since both lateral surfaces of the inverted conical shaped structure are arranged to contact a dam, corresponding adhesion can be improved, and peeling defects can be reduced or corrected.

[0019] Effects according to aspects of the present disclosure are not limited to the above description, and various effects will become apparent in the following description. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a cross-sectional view of a flexible display device having a spacer with a typical conical shape, and Fig. Figure 1B is a cross-sectional view of a flexible display device having a spacer with an inverted conical shape. Fig. 2 is a plan view illustrating a flexible display device according to aspects of the present disclosure. Fig. 3 is a cross-sectional view illustrating a flexible display device according to aspects of the present disclosure. Fig. 4A is a plan view illustrating a pixel included in a typical flexible display device, and Fig. 4B is an enlarged plan view of a portion of a flexible display device according to aspects of the present disclosure. Fig. 5A to Fig. 5G are cross-sectional views illustrating a manufacturing process of a flexible display device according to aspects of the present disclosure. DETAILED DESCRIPTION

[0020] The advantages and features of the present disclosure and methods for achieving the same will be made known with reference to embodiments of the present disclosure, which are described in detail below with reference to the accompanying drawings.

[0021] Furthermore, the shapes, sizes, ratios, angles, numbers, and the like illustrated in the accompanying drawings for describing the exemplary embodiments of the present disclosure are merely examples. Like reference numerals generally refer to like elements throughout the application. Furthermore, in the following description, a detailed description of known functions and configurations contained herein will be omitted when it is determined that the description would rather obscure the subject matter in some embodiments of the present disclosure.

[0022] It is intended that terms such as "comprise," "have," "include," "comprising," or the like, as used herein, generally be understood to add another component, except when used with the term "only." Singular forms used herein are intended to include plural forms unless the context clearly dictates otherwise.

[0023] In interpreting each element or feature of the embodiments of the present disclosure, it should be noted that all orders of magnitude and relative sizes of layers, areas, and regions have a tolerance or margin of error, even if there is no explicit description thereof.

[0024] Spatially related terms such as "on", "over", "above", "below", "under", "beneath", "underneath", "lower", "upper", "near", "close", "adjacent" and the like may be used herein to describe the relationship of an element or feature to one or more other elements or features as shown in the figures, and should be interpreted to mean that one or more other elements may be "interposed" between the elements, except when the terms such as "directly" or "only" are used.

[0025] Temporal terms such as “after,” “subsequent,” “next,” “before,” or the like, used herein to describe a temporal relationship between events, operations, or the like, are generally intended to include events, instances, operations, or the like that do not occur continuously, except when the terms such as “direct,” “immediate,” or the like are used.

[0026] When terms such as "first," "second," or the like are used herein to describe various elements or components, it should be noted that these elements or components are not limited thereto. These terms are used herein only to distinguish one element from other elements. Therefore, a first element described below may be a second element in a technical concept of the present disclosure.

[0027] It should be noted that the phrase "at least one" as used herein includes all combinations that can be achieved by combining one or more of the associated elements. For example, "at least one of a first element, a second element, and a third element" can include all combinations achieved by combining two or more of the first element, the second element, and the third element, as well as each of the first element, the second element, and the third element.

[0028] The elements or features of various exemplary embodiments of the present disclosure may be partially or fully connected or combined with one another and may be operated and controlled in various technical ways, as will be readily understood by those skilled in the art, and the various embodiments may be practiced independently of one another or may be practiced in relation to one another.

[0029] Hereinafter, examples of display devices in accordance with embodiments of the present disclosure will be discussed in detail with reference to the accompanying drawings. When assigning reference numerals to elements in the drawings, the same elements will be denoted by the same reference numerals even though the elements are illustrated in different drawings. A scale of the components illustrated in the accompanying drawings is illustrated for convenience of description and may be different from the actual scale; thus, embodiments of the present disclosure are not limited to the scale illustrated in the drawings.

[0030] Fig. 1A is a cross-sectional view of a flexible display device having a spacer with a typical conical shape, and Fig. Figure 1B is a cross-sectional view of a flexible display device having a spacer with an inverted conical shape.

[0031] Referring to Fig. 1A and Fig. 1B, a semiconductor layer 5 is disposed on a substrate 6, and a gate insulating layer 4 is disposed on the semiconductor layer 5. A gate electrode 3 is disposed on the gate insulating layer 4 so as to face the semiconductor layer 5. That is, the gate insulating layer 4 is sandwiched between the gate electrode 3 and the semiconductor layer 5. An insulating layer 7 is disposed on the gate electrode 3, and a source electrode 1 and a drain electrode 2 are disposed on the insulating layer 7. Each of the source electrode 1 and the drain electrode 2 is connected to the semiconductor layer 5 through an access hole formed in the insulating layer 7. Accordingly, a thin-film transistor comprising the semiconductor layer 5, the gate electrode 3, the source electrode 1, and the drain electrode 2 is disposed on the substrate 6.A protective layer 8 and a planarization layer 9 are disposed on the source electrode 1 and the drain electrode 2, and a reflective electrode 11 is disposed on the planarization layer 9. An organic light-emitting layer 12 and a common electrode 13 are disposed on the reflective electrode 11.

[0032] Considering characteristics of a flexible display device necessary in a flexible environment, in order to relieve a bending stress acting on various layers such as the organic light-emitting layer 12 and the like, a spacer 14 may be arranged on a dam layer 10 arranged on the planarization layer 9 and the reflective electrode 11.

[0033] Therefore, although the spacer 14 can relieve stress acting on the flexible display device when bending is performed, since the lower surface of the spacer 14 has a larger area than an upper surface thereof, the corresponding tensile stress cannot be significantly reduced. Indeed, a problem has arisen in that preventing peeling defects caused in the organic light-emitting layer 12 has little or no effect.

[0034] In this case, the spacer can be implemented to relieve both tensile and compressive loads in such a way that it has an inverted conical shape.

[0035] As in Fig. As shown in Fig. 1B, when a bending stress is applied, a spacer 14' having such an inverted conical shape arranged on the dam layer 10 can cause the stress to be dispersed; therefore, peeling of the organic light-emitting layer can be prevented and reliability of the device can be improved.

[0036] However, in a situation where the spacer 14' is positioned with the inverted conical shape, a problem arises in that particles are generated due to contact between the mask and the spacer between processes when metal mask deposition is performed. Such particles can cause adhesion contamination in subsequent processes and can result in reduced device yield; therefore, it is highly desirable to prevent or reduce the generation of these particles.

[0037] To address such a problem, according to aspects of the present disclosure, a flexible display device is provided in which, by having a spacer with an inverted conical shape, peeling of an organic light-emitting layer can be prevented, and the particle problem that may occur due to the spacer with the inverted conical shape can be reduced or solved (e.g., eliminated).

[0038] In the following, a flexible display device according to aspects of the present disclosure will be described with reference to Fig. 2 are described. Fig. 2 is a plan view illustrating the flexible display device according to aspects of the present disclosure.

[0039] Referring to Fig. 2, the flexible display device according to aspects of the present disclosure may include a display panel 100, a gate driver 200, a data driver 300, and a circuit board 400.

[0040] The display panel 100 comprises a substrate 110 (shown in Fig. 3), and the substrate 110 supports elements formed in an organic light-emitting element 180 (shown in Fig. 3). The substrate 110 may be formed from a material selected from groups consisting of polyester-based polymers, silicon-based polymers, acrylic-based polymers, polyolefin-based polymers, and combinations of two or more thereof, which are materials that exhibit flexibility when bent. However, embodiments of the present disclosure are not limited thereto. For example, glass formed in an ultra-thin shape may be used to implement a flexible display device.

[0041] The organic light-emitting element 180 is disposed above the substrate 110 and can emit light toward the outside of the display panel 100. The organic light-emitting element 180 can include a hole-injection layer, a hole-transport layer, an organic light-emitting layer, an electron-transport layer, and an electron-injection layer.

[0042] The substrate 110 may, in plan view, have a rectangular shape in which each corner region is rounded with a constant radius of curvature, or a non-rectangular shape having at least six sides. The substrate 110 with the non-rectangular shape may have at least one protrusion or at least one recess.

[0043] The substrate 110 may be divided into an active area AA (or a display area) and a non-active area NA (or a non-display area). The active area AA may be located in a central region of the substrate 110 and may be defined as an area for displaying images.

[0044] The active area AA may, in plan view, have a rectangular shape in which each corner region is rounded with a constant radius of curvature, or a non-rectangular shape having at least six sides. The active area AA with the non-rectangular shape may have at least one protrusion or at least one indentation.

[0045] The non-active region NA may be arranged at an edge region of the substrate 110 so as to surround the active region AA and may be defined as a region in which no images are displayed or an edge region.

[0046] A pixel P may be arranged in the active area AA of the substrate 110. In one embodiment, a plurality of pixels P may be arranged in a matrix form and positioned in the active area AA of the substrate 110.

[0047] The data driver 300 may be mounted by a chip mounting (or bonding) process in a mounting area defined in the non-active area NA of the substrate 110. The data driver 300 may receive multiple power levels or types, a timing synchronization signal, digital image data, and the like input from the circuit board 400, control the drive of the gate driver 200 by generating a gate control signal according to the timing synchronization signal, convert the digital image data into analog pixel data voltages, and provide the resulting pixel data voltages to one or more pixels P.

[0048] Although in Fig. 2, one or more dams may be arranged between the active region AA and the gate driver 200. In another embodiment, the dam may be arranged at an edge further away from the gate driver 200, for example, an outermost edge.

[0049] The display panel 100 can be bent or folded along a reference line II' parallel to the data driver 300. However, a direction or position of the reference line II' is not limited thereto. For example, the display panel 100 can be bent or folded in different directions or at different positions as necessary.

[0050] In the following, with further reference to Fig. 3 to Fig. 5, embodiments of the following disclosure will be described in detail.

[0051] Fig. 3 is a cross-sectional view illustrating a flexible display device according to aspects of the present disclosure.

[0052] Referring to Fig. 3, a flexible front-emitting display device according to aspects of the present disclosure includes a substrate 110, a thin film transistor 130, such as a driving thin film transistor, an organic light-emitting element 180, and at least one structure (170, 175).

[0053] The driving thin-film transistor 130 has a semiconductor layer 131, a gate electrode 134, a source electrode 133 and a drain electrode 132.

[0054] Semiconductor layer 131 is disposed over substrate 110. Semiconductor layer 131 may be implemented using an amorphous silicon layer or a polycrystalline silicon layer obtained by crystallizing amorphous silicon. One or more buffer layers 120 and 125 may be interposed between substrate 110 and semiconductor layer 131. Buffer layers 120 and 125 may be formed to protect the thin-film transistor from contaminants, such as alkali ions, that emanate from substrate 110 when semiconductor layer 131 is crystallized.

[0055] The gate electrode 134 is disposed on a first insulating layer 140 and overlaps with the semiconductor layer 131. In this case, the gate electrode 134 is connected to a gate line that provides a gate signal. The gate electrode 134 may be formed from a single layer or multiple layers composed of one or more of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy or alloys of two or more thereof.

[0056] The source electrode 133 and the drain electrode 132 are arranged to be spaced apart from each other by a predetermined distance and are electrically connected to the semiconductor layer 131. Specifically, a semiconductor layer contact hole exposing the semiconductor layer 131 is formed in the first insulating layer 140 and the second insulating layer 145, and the source electrode 133 and the drain electrode 132 are connected to the semiconductor layer 131 through the semiconductor layer contact hole.

[0057] An intermediate layer 150 is disposed on the driving thin-film transistor 130. A drain contact hole exposing the drain electrode 132 of the driving thin-film transistor 130 is formed in the intermediate layer 150.

[0058] Next, the organic light-emitting element 180 includes a first electrode 181, an organic light-emitting layer 182, and a second electrode 183. The organic light-emitting element 180 is electrically connected to the driving thin-film transistor 130. Specifically, the organic light-emitting element 180 is connected to the drain electrode 132 of the driving thin-film transistor 130 through the drain contact hole.

[0059] The first electrode 181 is disposed on the intermediate layer 150 and connected to the drain electrode 132 of the driving thin-film transistor 130 through the drain contact hole. The first electrode 181 serves to apply a current (or voltage) to the organic light-emitting layer 182 and defines a light-emitting region with a predetermined size.

[0060] The first electrode 181 acts as an anode. For this purpose, the first electrode 181 may be formed from a light-transmitting conductive material with a relatively high output energy. In one embodiment, the light-transmitting conductive material may comprise indium tin oxide (ITO) or indium zinc oxide (IZO). To improve reflection efficiency, the first electrode 181 may further comprise, in a lower portion of the first electrode, a reflective layer (not shown) formed from a metal material having a relatively high reflection efficiency. In one embodiment, the metal material may comprise one or more of silver (Ag), aluminum (Al), and an alloy thereof.

[0061] A dam 160 having a first opening exposing a portion of the first electrode 181 is disposed on the first electrode 181. The dam 160 may further have a second opening exposing a portion of the intermediate layer 150. Descriptions of these will be given below.

[0062] The organic light-emitting layer 182 is interposed between the first electrode 181 and the second electrode 183. The organic light-emitting layer 182 can emit light by combining holes provided by the first electrode 181 and electrons provided by the second electrode 183.

[0063] In one embodiment, Fig. 3 illustrates that the organic light-emitting layer 182 is arranged such that it overlaps all or at least part of the substrate. In another embodiment, the organic light-emitting layer 182 may be arranged only on the first electrode 181.

[0064] The organic light-emitting layer 182 may include a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer. The hole injection layer (not shown) is disposed on the first electrode 181 and serves to move holes. The hole transport layer (not shown) is disposed on the hole injection layer and serves to transport the holes injected by the hole injection layer to the light-emitting layer.

[0065] The light-emitting layer is inserted between the hole transport layer and the electron transport layer and can emit white light by combining holes provided by the first electrode and electrons provided by the second electrode 183.

[0066] The electron-transport layer (not shown) is disposed on the light-emitting layer and transports electrons injected from the electron-injection layer to the light-emitting layer. The electron-injection layer (not shown) is disposed on the electron-transport layer. Such an electron-injection layer may be omitted.

[0067] Furthermore, the light-emitting layer may include a first light-emitting stack and a second light-emitting stack that oppose each other, and an electric charge generation layer is interposed between the first light-emitting stack and the second light-emitting stack. In this case, since any one of the first light-emitting stack and the second light-emitting stack generates blue light and the other of the first light-emitting stack and the second light-emitting stack generates yellow-green light, white light can be generated by the first light-emitting stack and the second light-emitting stack. The white light generated in such light-emitting stacks can enter a color filter disposed in an upper portion or a lower portion of the light-emitting layer; thereby, color images can be implemented.

[0068] In another embodiment, color images of light-emitting layers can be generated by generating colored light corresponding to respective subpixels without a separate color filter. For example, a light-emitting layer of a red subpixel (R), a light-emitting layer of a green subpixel (G), and a light-emitting layer of a blue subpixel (B) can generate red light, green light, and blue light, respectively.

[0069] The second electrode 183 is disposed on the organic light-emitting layer 182 and provides electrons to the organic light-emitting layer 182. The second electrode 183 acts as a cathode. For this purpose, the second electrode 183 may be formed from a light-transmitting conductive material. In one embodiment, the light-transmitting conductive material may comprise indium tin oxide (ITO) or indium zinc oxide (IZO). The second electrode 183 may further comprise, in a portion contacting the organic light-emitting layer 182, a thin metal layer (not shown) made of a metal material with a low exit energy. For example, the metal material may comprise magnesium (Mg), silver (Ag), and compounds thereof.

[0070] The dam 160 may be disposed on the first electrode 181 of the organic light-emitting element 180 and the intermediate layer 150. The dam 160 serves to divide pixels P arranged adjacent to each other in the active region AA and may define a plurality of pixels P. The dam 160 may be formed of an organic material.

[0071] The dam 160 may include a first region exposing a portion of the intermediate layer 150, a second region exposing a portion of the first electrode 181, and a third region excluding the first region and the second region. The second region defined by the dam 160 may be the same as the light-emitting region defined by the first electrode 181.

[0072] At least one structure (170, 175) arranged in the display device comprises a first structure 170 with an inverted conical shape (i.e., a cross-sectional area of the first structure 170 decreases toward the substrate (i.e., from the top to the bottom)) and a second structure 175 with a conical shape (i.e., a cross-sectional area of the second structure 175 increases toward the substrate). In this case, the first structure 170 is arranged on the intermediate layer 150, and the second structure 175 is arranged on the dam 160.

[0073] The first structure 170 is arranged in the first region defined by the dam 160, and the second structure 175 is arranged on the third region defined by the dam 160.

[0074] The organic light-emitting layer 182 provides an access hole near the first region defined by the dam 160, exposing the dam 160. The organic light-emitting layer 182 is disposed on an upper portion, such as a top surface, of the first structure 170 by means of a shading effect and is not disposed in a portion below the upper portion of the first structure 170. Thus, an access hole is formed in the organic light-emitting layer 182.

[0075] In this case, both side surfaces of the first structure 170 are arranged to contact the dam 160; therefore, adhesion can be improved, and peeling defects can be reduced or corrected. Furthermore, an angle between at least one of the side surfaces of the first structure 170 and the intermediate layer 150 can be in a range of 20° to 80°.

[0076] The second structure 175 is arranged to be adjacent to the first structure 170 and spaced apart by a predetermined distance. The smaller such a distance between the first structure 170 and the second structure 175, the more a degree of freedom in design can be increased. In one embodiment, a distance between an end portion of an upper portion of the first structure 170 and an end portion of a lower portion of the second structure 175 may be 5 µm or less.

[0077] A thickness of the first structure 170 may be greater than that of the dam 160. The first structure 170 may be formed to have a thickness greater than that of the dam 160 to provide the shading effect for the organic light-emitting layer 182. In one embodiment, the thickness of the first structure 170 may be greater than 0.5 µm or greater than that of the dam 160.

[0078] A thickness of the second structure 175 may be greater than or equal to that of the dam 160. In one embodiment, the thickness of the second structure 175 may be 3 µm or less.

[0079] The organic light-emitting layer 182 and the second electrode 183 are arranged sequentially on the first structure 170 and the second structure 175.

[0080] An encapsulation layer 190 can prevent the penetration of oxygen or moisture from the outside to prevent a light-emitting material and an electrode material from being oxidized. When the organic light-emitting element is exposed to moisture or oxygen, a pixel shrinkage phenomenon in which a light-emitting area is reduced may occur, or a dark spot may be generated in the light-emitting area. The encapsulation layer 190 may be an inorganic layer formed of glass, metal, aluminum oxide (AlOx), or a silicon (Si)-based material, or a structure in which an organic layer and an inorganic layer are alternately stacked. The inorganic layer serves to prevent oxygen and moisture from entering, and the organic layer serves to allow the surface of the inorganic layer to have a uniform height.When the encapsulation layer 190 is formed of multiple thin film layers, it is possible that propagation paths of moisture or oxygen may be elongated and complicated, and such elongated and complicated propagation paths result in moisture or oxygen not penetrating to the organic light-emitting element.

[0081] The encapsulation layer 190 included in the display device according to aspects of the present disclosure may include a first encapsulation layer 191, a second encapsulation layer 192, and a third encapsulation layer 193. The first encapsulation layer 191 of the encapsulation layer 190 may be disposed on the second electrode 183. The second encapsulation layer 192 may be disposed on the first encapsulation layer 191. The third encapsulation layer 193 may be disposed on the second encapsulation layer 192. The first encapsulation layer 191 and the third encapsulation layer 193 of the encapsulation layer 190 may be formed of silicon nitride (SiNx), silicon oxide (SiOx), silicon oxynitride (SiON), aluminum oxide (Al2O3), or the like.The second encapsulation layer 192 of the encapsulation layer 190 may be formed of an organic material such as acrylic resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, and the like; however, embodiments of the present disclosure are not limited thereto.

[0082] Fig. 4A is a plan view illustrating a pixel included in a typical flexible display device, and Fig. 4B is an enlarged plan view of a portion of a flexible display device according to aspects of the present disclosure.

[0083] Referring to Fig. 4A and Fig. 4B, a first structure 170 and a second structure 175 are arranged between a plurality of pixels P.

[0084] In a flexible display device according to aspects of the present disclosure, the first structure 170 is arranged to be adjacent to the second structure 175. Accordingly, as a separating distance between the first structure 170 and the second structure 175 becomes smaller, it is possible to improve a degree of freedom in designing the flexible display device.

[0085] Fig. 5A to Fig. 5G are cross-sectional views illustrating a manufacturing process of a flexible display device according to aspects of the present disclosure.

[0086] Each of the Fig. 5A to Fig. 5G is a cross-sectional view showing a manufacturing process of a pixel that is used in Fig. 3 and Fig. 4. Thus, like elements are designated by like reference numerals, the details of which are not repeated herein for convenience of description.

[0087] Referring to Fig. 5A, the semiconductor layer 131, the first insulating layer 140, the gate electrode 134, the second insulating layer 145, the source electrode 133, the drain electrode 132, and the intermediate layer 150 are sequentially arranged on the substrate 110.

[0088] The semiconductor layer 131 and the gate electrode 134 can be patterned by a so-called photolithography process, that is, by depositing a predetermined metal material on the substrate 110, applying a photoresin thereto, and then irradiating and developing the photoresin to form a mask pattern, etching a predetermined area of the metal material using the mask pattern, and removing the mask pattern.

[0089] It should be noted that the patterning of the semiconductor layer 131 and the gate electrode 134 is not necessarily limited to this. For example, the semiconductor layer 131 and the gate electrode 134 can be patterned directly on a metal paste by a printing method such as screen printing, inkjet printing, gravure printing, offset gravure printing, offset back printing, flexographic printing, or microcontact printing.

[0090] A process of patterning each element described below can also be performed using the photolithography process or the printing method, depending on the materials involved; thus, for convenience of description, corresponding descriptions are not repeated. A semiconductor layer contact hole is formed in the first insulating layer 140 and the second insulating layer 145. Such a semiconductor layer contact hole is formed to expose a part of the semiconductor layer 131 by etching the first insulating layer 140 and the second insulating layer 145.

[0091] The source electrode 133 and the drain electrode 132 are patterned such that they are connected to the semiconductor layer 131 through the semiconductor layer contact hole and are arranged at a distance from the gate electrode 134.

[0092] A drain contact hole is formed in the intermediate layer 150. Such a drain contact hole is formed to expose a portion of the drain electrode 132 by etching the intermediate layer 150.

[0093] Referring to Fig. 5B, the first electrode 181 is formed over the substrate 110 over which the intermediate layer 150 is formed.

[0094] The first electrode 181 is structured such that it is connected to the drain electrode 132 through the drain contact hole.

[0095] Referring to Fig. 5C, the first structure 170 is formed on the intermediate layer 150.

[0096] In this case, the first structure 170 has an inverted conical shape, meaning that its cross-sectional area decreases toward the substrate (from the top to the bottom). A position where the first structure 170 is formed may correspond to the first region defined by the dam 160.

[0097] Next, with reference to Fig. 5D, the dam 160 having an opening in the first region is formed on the first electrode 181 and the intermediate layer 150.

[0098] The dam 160 is formed by depositing a predetermined material over a surface of the substrate 110 and removing a predetermined portion of the deposited material through an etching process such that it has an opening in the second region. As a result, the first electrode 181 may be exposed in the second region. Furthermore, since the first structure 170 is formed before the dam 160, the dam 160 is formed such that it contacts the first structure 170 in the first region.

[0099] Referring to Fig. 5E, the second structure 175 is formed in the third region defined by the dam 160. In this case, the second structure 175 has a conical shape, meaning that a cross-sectional area thereof increases toward the substrate (from the top to the bottom).

[0100] The first structure 170 and the second structure 175 are arranged at a distance from each other, and a distance between an end portion of an upper portion of the first structure 170 and an end portion of a lower portion of the second structure 175 may be 5 µm or less.

[0101] Referring to Fig. 5F, the organic light-emitting layer 182 is formed over the surface of the substrate 110. For example, the organic light-emitting layer 182 is formed such that it overlaps all or at least a portion of the substrate 110 in a plan view.

[0102] The organic light-emitting layer 182 is formed using thermal vacuum evaporation. Thermal vacuum evaporation causes an organic material to enter the substrate 110 in a direction perpendicular to the substrate.

[0103] The organic light-emitting layer 182 is formed such that it is electrically connected to the first electrode 181 in the second region defined by the dam 160. Furthermore, the organic light-emitting layer 182 is formed such that it has an access hole near the first region, exposing a portion of the dam 160. The access hole is formed by the first structure 170 formed in the first region.

[0104] Referring to Fig. 5G, the second electrode 183 is formed over all or at least a portion of the surface of the substrate 110.

[0105] The second electrode 183 is formed by thermal vacuum evaporation of a predetermined metal material. In this case, the predetermined metal material enters in a direction perpendicular to the substrate 110 and is deposited on the organic light-emitting layer 182.

[0106] The organic light-emitting layer 182 is disposed on an upper portion, such as a top surface, of the first structure 170 by means of the shading effect, and is not formed in a portion below the upper portion of the first structure 170.

[0107] Thus, by forming the first structure 170 in an opening of the dam 160, even if a structure having an inverted conical shape is formed, a display panel 100 can have a thickness equal to that in a display panel in which the structure having the inverted conical shape is not formed. When an inverted conical structure is formed, considering that a height of a cone is greater than 3 μm, a flexible display device can generally be formed to have a small thickness, and thus an advantage is provided in that a thin flexible display device is implemented.Furthermore, since the structure having the inverted conical shape is positioned lower than the structure having the conical shape, particles can be prevented from being generated due to contact between the mask and the structure having the inverted conical shape when metal mask deposition is performed. Thus, even when the structure having the inverted conical shape is present in the flexible display device, the particle problem that may occur in a deposition process can be reduced or solved (e.g., eliminated).

[0108] Furthermore, since an inverted conical structure for preventing a lateral leakage current between adjacent pixels P through the organic light-emitting layer 182 is positioned to be adjacent to a conical shape, it is possible to produce an effect of improving the degree of freedom in designing the display device.

[0109] Flexible display devices according to embodiments herein may be described as follows.

[0110] A flexible display device according to embodiments herein comprises a substrate over which a thin-film transistor is arranged, an intermediate layer arranged to cover the thin-film transistor, a first electrode positioned on the intermediate layer and connected to the thin-film transistor, a dam positioned on the intermediate layer and the first electrode and defining a first region exposing a part of the intermediate layer, a second region exposing a part of the first electrode, and a third region outside the first region and the second region, a first structure positioned in the first region defined by the dam and shaped inversely conically towards the substrate, an organic light-emitting layer positioned on the first electrode exposed in the second region, a second electrode,which is arranged on the organic light-emitting layer, and a second structure which is arranged in the third region defined by the dam, wherein a cross-sectional area of the second structure becomes larger towards the substrate, that is to say is conically shaped towards the substrate, wherein the first structure is arranged such that it touches the intermediate layer, and both side surfaces of the first structure touch the dam.

[0111] In the flexible display device according to embodiments herein, a thickness of the first structure may be greater than that of the dam.

[0112] In the flexible display device according to embodiments herein, a thickness of the second structure may be less than 3 µm.

[0113] In the flexible display device according to embodiments herein, a separating distance between the first structure and the second structure may be 5 µm or less.

[0114] A method for manufacturing a flexible display device according to embodiments herein may include a step of disposing an intermediate layer such that it covers a thin-film transistor over a substrate over which the thin-film transistor is disposed, a step of disposing a first electrode electrically connected to the thin-film transistor on the intermediate layer, a step of disposing, on the intermediate layer, a first structure such that it is disposed at a distance from the first electrode and is invertedly conically shaped toward the substrate, a step of disposing a dam on the intermediate layer and the first electrode, a step of disposing an organic light-emitting layer on the first electrode, a step of disposing a second electrode such that it overlaps with all or at least a part of the substrate on the organic light-emitting layer,and a step of arranging a second structure, which is conically shaped toward the substrate, on the dam, wherein the dam is arranged such that it touches both side surfaces of the first structure.,

[0115] Embodiments described herein for the flexible display device(s) can also be applied to the method(s) for manufacturing a flexible display device, and vice versa. Features, structures, effects, and the like described in the examples and embodiments herein are included in at least one example or embodiment of the present disclosure and are not necessarily limited to one example or embodiment. Furthermore, the features, structures, effects, etc. described in at least one example or embodiment of the present disclosure can be combined for further examples by one skilled in the art to which the present disclosure pertains.

Claims

[1] A flexible display device comprising: a substrate (110) over which a thin-film transistor (130) is arranged; an intermediate layer (150) arranged to cover the thin film transistor (130); a first electrode (181) disposed on the intermediate layer (150) and connected to the thin-film transistor (130); a dam (160) disposed on the intermediate layer (150) and the first electrode (181) and defining a first region exposing a portion of the intermediate layer (150), a second region exposing a portion of the first electrode (181), and a third region outside the first region and the second region; a first structure (170) arranged in the first region defined by the dam (160) and having an inverted conical shape toward the substrate (110); an organic light-emitting layer (182) disposed on the first electrode (181) exposed in the second region; a second electrode (183) disposed on the organic light-emitting layer (182); and a second structure (175) arranged on the dam (160) in the third region, wherein the second structure (175) is conically shaped towards the substrate (110), wherein the first structure (170) is arranged to contact the intermediate layer (150) and both side surfaces of the first structure (170) contact the dam (160). [2] The flexible display device according to claim 1, wherein the organic light-emitting layer (182) is arranged on the first structure (170). [3] The flexible display device according to one of claims 1 to 2, wherein a thickness of the first structure (170) is greater than a thickness of the dam (160). [4] The flexible display device according to any one of claims 1 to 3, wherein a thickness of the second structure (175) is less than 3 µm. [5] The flexible display device according to any one of claims 1 to 4, wherein a separating distance between the first structure (170) and the second structure (175) is 5 µm or less. [6] A method of manufacturing a flexible display device, comprising: Arranging an intermediate layer (150) such that it covers a thin-film transistor (130) over a substrate (110) over which the thin-film transistor (130) is arranged; Arranging a first electrode (181) electrically connected to the thin-film transistor (130) on the intermediate layer (150); Arranging, on the intermediate layer (150), a first structure (170) such that it is arranged at a distance from the first electrode (181) and is invertedly conical in shape towards the substrate (110); Arranging a dam (160) on the intermediate layer (150) and the first electrode (181) such that a part of the first electrode (181) is exposed; Arranging an organic light-emitting layer (182) on the first electrode (181); Arranging a second electrode (183) on the organic light-emitting layer (182) such that it overlaps with all or part of the substrate (110); and Arranging a second structure (175) which is conically shaped towards the substrate (110) on the dam (160), wherein the dam (160) is arranged to contact both side surfaces of the first structure (170). [7] The method according to claim 6, wherein a thickness of the second structure (175) is less than 3 µm. [8] The method according to any one of claims 6 to 7, wherein a separating distance between the first structure (170) and the second structure (175) is 5 µm or less.

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