Flexible display device and manufacturing method thereof

Abstract

A flexible display device and a method for manufacturing the flexible display device are disclosed. The method for manufacturing the flexible display device includes: preparing a substrate; forming a first charge adhesion layer having a first charge on the substrate; forming a second charge adhesion layer having a second charge opposite to the first charge on the first charge adhesion layer; forming a first charge adhesion pattern and a second charge adhesion pattern by removing an edge of each of the first charge adhesion layer and the second charge adhesion layer; forming a flexible substrate on the substrate having the first charge adhesion pattern and the second charge adhesion pattern formed thereon; forming a display unit on the flexible substrate; cutting the substrate, the first charge adhesion pattern, the second charge adhesion pattern, the flexible substrate and the display unit along a cutting line; and separating the substrate and the flexible substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2018-0137566, filed on November 9, 2018, which is hereby incorporated by reference for all purposes as if fully set forth herein. Technical Field

[0003] Exemplary embodiments / implementations of the present invention generally relate to flexible display devices and methods of manufacturing the same, and more particularly, to transparent flexible display devices and methods of manufacturing the same. Background Art

[0004] A display device is a device for displaying an image. In recent years, organic light-emitting display devices have attracted attention. Organic light-emitting display devices have the characteristics of low power consumption, high brightness, and high response speed.

[0005] Organic light-emitting devices can have flexible properties by using a flexible organic light-emitting display panel and transparent properties by using a transparent organic light-emitting display panel. In order to manufacture an organic light-emitting display panel, a method of bonding a flexible substrate to a substrate, then performing subsequent processes, and separating the flexible substrate from the substrate is introduced.

[0006] However, in a process of separating the flexible substrate from the substrate using laser, they may not be uniformly separated from each other, or the flexible display device may be thermally degraded to reduce its transmittance.

[0007] The above information disclosed in this Background section is only for understanding the background of the present inventive concept and therefore it may contain information that does not constitute the prior art. Summary of the invention

[0008] The present disclosure provides a transparent flexible display device having high transmittance by easily separating a substrate and a flexible substrate without laser irradiation.

[0009] The present disclosure also provides a method for manufacturing a transparent flexible display device in which a substrate and a flexible substrate are not easily separated due to direct contact between the substrate and the flexible substrate in a process of forming a display unit.

[0010] Additional features of the inventive concept will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concept.

[0011] An embodiment of the present inventive concept provides a method for manufacturing a flexible display device, the method comprising: preparing a substrate; forming a first charge adhesion layer having a first charge on the substrate; forming a second charge adhesion layer having a second charge opposite to the first charge on the first charge adhesion layer; forming a first charge adhesion pattern and a second charge adhesion pattern by removing an edge of each of the first charge adhesion layer and the second charge adhesion layer; forming a flexible substrate on the substrate having the first charge adhesion pattern and the second charge adhesion pattern formed thereon; forming a display unit on the flexible substrate; cutting the substrate, the first charge adhesion pattern, the second charge adhesion pattern, the flexible substrate and the display unit along a cutting line; and separating the substrate and the flexible substrate.

[0012] In an embodiment, the first charge adhesion layer may include graphene oxide.

[0013] In an embodiment, the second charge adhesion layer may include montmorillonite, molybdenum disulfide, or hexagonal boron nitride (hBN).

[0014] In an embodiment, the first and second charge adhesion patterns may be formed by removing a portion of each of the first and second charge adhesion layers by spraying a gas in a plasma state where nitrogen gas and air are mixed.

[0015] In an implementation, a portion of a top surface of the substrate may be exposed by forming the first charge adhesion pattern and the second charge adhesion pattern.

[0016] In an embodiment, by forming the flexible substrate, the flexible substrate may be in contact with the portion of the substrate exposed by the first charge adhesion pattern and the second charge adhesion pattern.

[0017] In an embodiment, forming the flexible substrate may be formed by applying a polymer material over an area larger than an area occupied by the first charge adhesion pattern and the second charge adhesion pattern.

[0018] In an implementation, the cutting line may be defined to overlap the first charge adhesion pattern and the second charge adhesion pattern on a plane.

[0019] In an implementation, the cutting line may have a closed loop shape on a plane, and may be defined along an edge of each of the first charge adhesion pattern and the second charge adhesion pattern.

[0020] In an embodiment, the second charge adhesion layer may remain on the flexible substrate by separating the substrate from the flexible substrate.

[0021] In an embodiment of the present invention, a method for manufacturing a flexible display device includes: preparing a substrate; forming a lower first charge adhesion layer having a first charge on the substrate; forming a lower second charge adhesion layer having a second charge opposite to the first charge on the lower first charge adhesion layer; forming an upper first charge adhesion layer having a first charge on the lower second charge adhesion layer; forming an upper second charge adhesion layer having a second charge on the upper first charge adhesion layer; removing the lower first charge adhesion layer, the lower second charge adhesion layer, the upper first charge adhesion layer, and the upper second charge adhesion layer; The invention relates to a method for forming a lower first charge bonding pattern, a lower second charge bonding pattern, an upper first charge bonding pattern and an upper second charge bonding pattern by cutting the edges of each; forming a flexible substrate on the substrate on which the lower first charge bonding pattern, the lower second charge bonding pattern, the upper first charge bonding pattern and the upper second charge bonding pattern are formed; forming a display unit on the flexible substrate; cutting the substrate, the lower first charge bonding pattern, the lower second charge bonding pattern, the upper first charge bonding pattern, the upper second charge bonding pattern, the flexible substrate and the display unit along a cutting line; and separating the substrate and the flexible substrate.

[0022] In an embodiment, the lower first charge adhesion layer may include graphene oxide, and the upper first charge adhesion layer may include polyethyleneimine (PEI).

[0023] In an embodiment, each of the lower second charge bonding layer and the upper second charge bonding layer may include montmorillonite, molybdenum disulfide, or hexagonal boron nitride (hBN).

[0024] In an embodiment, the upper first charge adhesion pattern and the upper second charge adhesion pattern may remain on the flexible substrate by separating the substrate from the flexible substrate.

[0025] In an embodiment, the lower second charge adhesion pattern, the upper first charge adhesion pattern, and the upper second charge adhesion pattern may remain on the flexible substrate by separating the substrate from the flexible substrate.

[0026] In an embodiment of the present inventive concept, a flexible display device includes a flexible substrate, a circuit element layer arranged on the flexible substrate, a display element layer arranged on the circuit element layer and including an organic light emitting diode, an encapsulation layer arranged on the display element layer to seal the display element layer, and a charge adhesion layer contacting a lower portion of the flexible substrate, the charge adhesion layer having a charge and including montmorillonite, molybdenum disulfide, or hexagonal boron nitride (hBN).

[0027] In an implementation, the charge adhesion layer may have a bottom surface having a concavo-convex shape.

[0028] In an embodiment, the concavo-convex shape of the bottom surface of the charge adhesion layer may be randomly distributed.

[0029] In an implementation, the concavo-convex shape of the bottom surface of the charge adhesion layer may have a height of about 1 nm or less.

[0030] In an embodiment, the flexible display device may further include a lower charge adhesion layer contacting a lower portion of the charge adhesion layer, and the lower charge adhesion layer may include polyethyleneimine (PEI).

[0031] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate exemplary embodiments of the present invention and together with the description are used to explain the inventive concept. In the accompanying drawings:

[0033] Figure 1 is a flow chart showing a method for manufacturing a flexible display device according to an embodiment of the inventive concept;

[0034] Figure 2A , Figure 3A , Figure 4A and Figure 5A is a plan view showing a manufacturing process of forming a flexible display device according to an embodiment of the inventive concept, and Figure 2B , Figure 3B , Figure 4B , Figure 5B , Figure 6 and Figure 7 is a cross-sectional view illustrating a manufacturing process of forming a flexible display device according to an embodiment of the inventive concept;

[0035] Figure 8 is a graph showing test results of adhesion of a first charge adhesion pattern and a second charge adhesion pattern;

[0036] Fig. 9 It shows that according to Figure 7 A photograph of a bottom surface of a transparent flexible display module according to an embodiment of the present inventive concept;

[0037] Fig. 10A It is shown Figure 7 A plan view of a transparent flexible display module DPA in FIG. Fig. 10B is along Fig. 10A A cross-sectional view taken along line II-II'; and

[0038] Fig.11 and Fig.12is a cross-sectional view illustrating a manufacturing process for forming a flexible display device according to another embodiment of the inventive concept. DETAILED DESCRIPTION

[0039] In the following description, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of various exemplary embodiments or implementations of the present invention. As used herein, "implementation" and "implementation" are interchangeable words, which are non-limiting examples of one or more devices or methods of the inventive concept disclosed herein. However, it is apparent that various exemplary embodiments can be practiced without these specific details, or with one or more equivalent arrangements. In other examples, known structures and devices are shown in block diagram form to avoid unnecessary confusion of various exemplary embodiments. In addition, various exemplary embodiments may be different, but need not be exclusive. For example, without departing from the inventive concept, the specific shape, configuration and characteristics of the exemplary embodiment may be used or implemented in another exemplary embodiment.

[0040] Unless otherwise specified, the exemplary embodiments shown should be understood as providing exemplary features of different details that can implement some ways of the inventive concept in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions and / or aspects of various embodiments (hereinafter individually or collectively referred to as "elements") can be combined, separated, interchanged and / or rearranged in other ways without departing from the inventive concept.

[0041] The use of cross hatching and / or shading in the drawings is generally provided to clarify the boundaries between adjacent elements. Thus, unless otherwise specified, the presence or absence of cross hatching or shading will not convey or indicate any preference or requirement for a particular material, material property, size, ratio, commonality between the elements shown and / or any other characteristics, attributes, properties, etc. of the elements. In addition, in the drawings, the size and relative size of the elements may be exaggerated for the purpose of clarity and / or description. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed differently from the described sequence. For example, two processes described in succession can be performed substantially simultaneously or in an order opposite to the described order. Moreover, the same reference numerals represent the same elements.

[0042] When an element or layer is referred to as being "on" another element or layer, "connected to" or "coupled to" another element or layer, it may be directly on, connected to or coupled to another element or layer, or there may be an intermediate element or layer. However, when an element or layer is referred to as being "directly on" another element or layer, "directly connected to" or "directly coupled to" another element or layer, there is no intermediate element or layer. For this reason, the term "connection" may indicate a physical, electrical and / or fluid connection with or without an intermediate element. In addition, the D1-axis, D2-axis and D3-axis are not limited to the three axes of a rectangular coordinate system (such as an x-axis, a y-axis and a z-axis), and may be interpreted as a broader meaning. For example, the D1-axis, D2-axis and D3-axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purposes of this disclosure, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] Although the terms "first", "second", etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Therefore, without departing from the teachings of the present disclosure, the first element discussed below may be referred to as the second element.

[0044] Spatially relative terms, such as "beneath," "below," "under," "lower," "above," "upper," "over," "higher," "side" (e.g., as in "sidewall"), and the like, may be used herein for descriptive purposes and, therefore, to describe the relationship of one element to another element as shown in the accompanying drawings. Spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, elements described as being "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" may include both orientations of above and below. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and thus, the spatially relative descriptors used herein are interpreted accordingly.

[0045] The terms used herein are for the purpose of describing specific embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used herein are also intended to include the plural forms. In addition, when the terms "comprise", "comprising", "include", and / or "including" are used in this specification, the existence of the stated features, wholes, steps, operations, elements, parts, and / or clusters thereof is described, but the existence or addition of one or more other features, wholes, steps, operations, elements, parts, and / or clusters thereof is not excluded. It is also noted that, as used herein, the terms "substantially", "about", and other similar terms are used as terms of approximation rather than terms of degree, and thus, are used to take into account the inherent deviations of measured values, calculated values, and / or provided values ​​that will be recognized by those of ordinary skill in the art.

[0046] Various exemplary embodiments are described herein with reference to cross-sectional views and / or exploded views that are schematic illustrations of idealized exemplary embodiments and / or intermediate structures. Thus, variations in the shapes of the illustrations resulting from, for example, manufacturing techniques and / or tolerances are to be expected. Therefore, the exemplary embodiments disclosed herein should not necessarily be interpreted as being limited to the specific illustrated zone shapes, but rather include deviations in shape resulting from, for example, manufacturing. In this way, the zones shown in the drawings may be schematic in nature, and the shapes of these zones may not reflect the actual shapes of the zones of the device, and are therefore not necessarily intended to be limiting.

[0047] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. Unless explicitly defined as such herein, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and should not be interpreted in an idealized or overly formal sense.

[0048] Hereinafter, a display device according to an embodiment of the inventive concept will be described with reference to the accompanying drawings.

[0049] Figure 1 is a flowchart showing a method for manufacturing a flexible display device according to an embodiment of the present inventive concept, Figure 2A , Figure 3A , Figure 4A and Figure 5A is a plan view showing a manufacturing process of a flexible display device according to an embodiment of the inventive concept, and Figure 2B , Figure 3B, Figure 4B , Figure 5B , Figure 6 and Figure 7 is a cross-sectional view illustrating a manufacturing process of a flexible display device according to an embodiment of the inventive concept. Figure 2B , Figure 3B , Figure 4B and Figure 5B Along Figure 2A , Figure 3A , Figure 4A and Figure 5A A cross-sectional view taken along line II'.

[0050] Reference Figure 1 , first, a substrate 100 is prepared in operation S0.

[0051] Figure 2B The substrate 100 may be a glass substrate, a polymer film or a silicon wafer, which supports the flexible substrate 300 (refer to Figure 4A and Figure 4B ) to form a flexible display device. However, embodiments of the inventive concept are not limited thereto. For example, the substrate 100 may be made of any material having an electric charge.

[0052] Thereafter, the surface of the substrate 100 may be further processed so that the substrate 100 (see Figure 2A and Figure 2B ) has a second charge opposite to the first charge. Here, the substrate 100 may be plasma-treated to have the second charge. In an embodiment of the inventive concept, the second charge may be a negative charge.

[0053] Reference Figure 1 , Figure 2A and Figure 2B , in operation S10 , a first charge adhesion layer having a first charge is formed on the substrate 100 .

[0054] A solution containing graphene oxide having a first charge may be applied to the substrate 100. In addition to dip coating, the coating method may be one selected from a group consisting of spray coating, spin coating, screen printing, offset printing, inkjet printing, pad printing, scraping, kiss coating, gravure coating, brush coating, ultrasonic micro-spray coating, and spray coating. However, embodiments of the present inventive concept are not limited thereto, and any coating method may be used as desired.

[0055] Thereafter, a first charge adhesion layer 210a having a first charge may be formed by performing an operation of removing foreign matter in the graphene oxide solution applied on the substrate 100 and a drying process. In an embodiment of the present inventive concept, the first charge may be a positive charge.

[0056] Thereafter, in operation S20, a second charge adhesion layer 220a having a second charge is formed on the first charge adhesion layer 210a.

[0057] The second charge adhesion layer 220a may include transparent montmorillonite, molybdenum disulfide (MoS 2 ) and hexagonal boron nitride (hBN). The montmorillonite having the second charge, molybdenum disulfide (MoS 2 ) or hexagonal boron nitride (hBN) solution is applied on the first charge adhesion layer 210a. In addition to dip coating, the coating method may be one selected from the group consisting of spray coating, spin coating, screen printing, offset printing, inkjet printing, pad printing, scraping, kiss coating, gravure coating, brush coating, ultrasonic micro-spray coating and spray spray coating. However, embodiments of the present inventive concept are not limited thereto and may include any other coating method.

[0058] Thereafter, the second charge adhesion layer 220a having the second charge may be formed by performing a process on a substrate including montmorillonite, molybdenum disulfide (MoS 2 ) or hexagonal boron nitride (hBN) solution by removing foreign matter and drying. In an embodiment of the present inventive concept, the second charge may be a negative charge.

[0059] Each of montmorillonite and molybdenum disulfide may be a substantially transparent material. Accordingly, as described later, although a solution may partially remain on the rear surface of the flexible substrate when manufacturing a transparent flexible display device, high transmittance may be ensured.

[0060] In reference Figure 2A and Figure 2B In the described embodiments of the present inventive concept, although a pair of the first charge adhesion layer 210a and the second charge adhesion layer 220a are exemplarily described, reference may be made repeatedly to Figure 2A and Figure 2B The process is described to form two or more pairs of the first charge adhesion layer 210a and the second charge adhesion layer 220a.

[0061] Afterwards, refer to Figure 1 , Figure 3A and Figure 3B In operation S30, the first charge adhesion pattern 210 and the second charge adhesion pattern 220 are formed by removing a portion of an edge of each of the first charge adhesion layer 210a and the second charge adhesion layer 220a.

[0062] In a plane, the first area AR1 and the second area AR2 may be defined on the laminated first charge adhesion layer 210a and the second charge adhesion layer 220a. The first area AR1 may have a rectangular shape. The second area AR2 may surround the first area AR1 as an edge area of ​​the first area AR1. However, embodiments of the inventive concept are not limited thereto. For example, the second area AR2 may surround three sides of the first area AR1, rather than completely surrounding the first area AR1.

[0063] Thereafter, a portion of each of the first and second charge adhesion layers 210a and 220a corresponding to the second area AR2 may be removed by spraying a gas in a plasma state in which nitrogen gas and air are mixed.

[0064] Operation S30 is performed, and then a portion of the top surface of the substrate 100 may be exposed.

[0065] Afterwards, refer to Figure 1 , Figure 4A and Figure 4B In operation S40 , a flexible substrate 300 is formed on the substrate 100 on which the second charge adhesion pattern 220 is formed.

[0066] The flexible substrate 300 is a substantially transparent or transflective plastic substrate having flexibility. The flexible substrate 300 may be made of a material selected from the group consisting of polyester, vinyl polymer, polycarbonate, polyethylene, polyacetate, polyimide, polyethersulfone (PES), polyacrylate (PAR), polyethylene naphthalate (PEN) and polyethylene terephthalate (PET).

[0067] The flexible substrate 300 can be formed by applying and curing a polymer material on the first charge adhesion pattern 210 and the second charge adhesion pattern 220. Here, the polymer material can be applied on an area larger than the area occupied by the first charge adhesion pattern 210 and the second charge adhesion pattern 220. The applied polymer material can completely cover the first charge adhesion pattern 210 and the second charge adhesion pattern 220. In addition to dip coating, the coating method can be selected from a cluster consisting of spray coating, spin coating, screen printing, offset printing, inkjet printing, pad printing, scraping, kiss coating, gravure coating, brushing, ultrasonic micro-spraying and spray spraying. However, the embodiments of the present inventive concept are not limited thereto. For example, the coating method may include another coating method.

[0068] Through operation S40 , the flexible substrate 300 may be in contact with a portion of the top surface of the substrate exposed in operation S30 .

[0069] Afterwards, refer to Figure 1 , Figure 5A and Figure 5B, in operation S50 , a display unit 400 is formed on the flexible substrate 300 .

[0070] The display unit 400 may be formed by sequentially forming a circuit element layer, a display element layer, and an encapsulation layer. The structure of the display unit 400 will be described later, but a description of a detailed method of forming the display unit 400 will be omitted.

[0071] Reference Figure 4A , Figure 4B , Figure 5A and Figure 5B , a central area CTA and a peripheral area PRA may be defined on the flexible substrate 300. The central area CTA overlaps the first charge adhesion pattern 210 and the second charge adhesion pattern 220, and the peripheral area PRA does not overlap the first charge adhesion pattern 210 and the second charge adhesion pattern 220.

[0072] The first charge adhesion pattern 210 and the second charge adhesion pattern 220 having opposite polarities to each other are located between the substrate 100 and the flexible substrate 300 on the central area CTA. Van der Waals force, as a molecular force, acts between the first charge adhesion pattern 210 and the second charge adhesion pattern 220. Accordingly, the adhesion force between the substrate 100 and the flexible substrate 300 on the central area CTA is relatively low.

[0073] The substrate 100 and the flexible substrate 300 are in direct contact with each other on the peripheral area PRA. The adhesive force between the substrate 100 and the flexible substrate 300 on the peripheral area PRA is relatively greater than the adhesive force between the substrate 100 and the flexible substrate 300 on the central area CTA. In the peripheral area PRA where the substrate 100 and the flexible substrate 300 are in direct contact with each other, the adhesive force between the substrate 100 and the flexible substrate 300 can be increased by a process of forming the display unit 400 on the flexible substrate 300, in particular, by a process of forming a barrier layer on the flexible substrate 300 for preventing moisture or oxygen from entering.

[0074] When forming the display unit 400, the module on which the substrate 100, the first charge adhesion pattern 210, the second charge adhesion pattern 220, and the flexible substrate 300 are formed may be moved or turned over. In the peripheral area PRA, the flexible substrate 300 is directly placed on the substrate 100 with a stronger adhesion force than that of the central area CTA having different charge regions therebetween. Because the substrate 100 and the flexible substrate 300 in the central area CTA have a low adhesion force due to the first charge adhesion pattern 210 and the second charge adhesion pattern 220, in the case of the peripheral area PRA where there is no flexible substrate 300 directly contacting the substrate 100, the substrate 100 and the flexible substrate 300 may be easily separated and subsequent processes may not be performed.

[0075] In the method for manufacturing a flexible display device according to an embodiment of the inventive concept, since the substrate 100 and the flexible substrate 300 are in direct contact with each other in the peripheral area PRA to have a relatively large adhesive force therebetween, the substrate 100 and the flexible substrate 300 may not be easily separated in the process of forming the display unit 400.

[0076] The first charge adhesion pattern 210 and the second charge adhesion pattern 220 disposed between the substrate 100 and the flexible substrate 300 have an adhesion force that is relatively weaker than the adhesion force of the region where the substrate 100 and the flexible substrate 300 are directly in contact with each other. However, the first charge adhesion pattern 210 and the second charge adhesion pattern 220 must have an adhesion force that is not less than a reference value. When the first charge adhesion pattern 210 and the second charge adhesion pattern 220 have an adhesion force less than the reference value, and the module on which the substrate 100, the first charge adhesion pattern 210, the second charge adhesion pattern 220, and the flexible substrate 300 are formed is turned over, although the substrate 100 and the flexible substrate 300 are attached to each other in the peripheral area PRA, as the substrate 100 and the flexible substrate 300 are separated from each other in the central area CTA, the flexible substrate 300 may be deflected due to its own weight.

[0077] Therefore, the first charge adhesion pattern 210 and the second charge adhesion pattern 220 may have an adhesion force ranging from about 1 gf / in to about 10 gf / in.

[0078] Figure 8 2 is a graph showing the test results of the adhesion of the first charge adhesion pattern 210 and the second charge adhesion pattern 220. Figure 8 In the embodiment, the adhesion force when two to four pairs of the first charge adhesion patterns 210 and the second charge adhesion patterns 220 are provided.

[0079] When two to four pairs of the first and second charge adhesion patterns 210 and 220 are provided, adhesion therebetween satisfies a range of about 1 gf / in to about 10 gf / in, and specifically, a range of 3 gf / in to about 8 gf / in.

[0080] Reference FIG. 5A to FIG. 5B In operation S60, the substrate 100, the first charge adhesion pattern 210, the second charge adhesion pattern 220, the flexible substrate 300, and the display unit 400 are cut along the cutting line CTL.

[0081] The cutting line CTL may overlap the first and second charge adhesion patterns 210 and 220 in a plane. The cutting line CTL may have a closed loop shape in a plane and be defined along an edge of each of the first and second charge adhesion patterns 210 and 220.

[0082] Accordingly, the peripheral area PRA of the flexible substrate 300 is removed, and only the central area CTA remains. That is, the substrate 100 and the flexible substrate 300 are attached to each other only by the first charge adhesion pattern 210 and the second charge adhesion pattern 220 .

[0083] Reference Figure 6 , as the substrate 100, the first charge adhesion pattern 210, the second charge adhesion pattern 220, the flexible substrate 300, and the display unit 400 are cut, a display module DM is generated.

[0084] Afterwards, refer to Figure 1 and Figure 7 , in operation S70, the substrate 100 and the flexible substrate 300 are separated from the display module DM.

[0085] The substrate 100 and the flexible substrate 300 may be separated by a vacuum suction device. The substrate 100 and the flexible substrate 300 may be separated by fixing the display unit 400 on a vacuum suction table, and then suctioning the substrate 100 to apply a force to the substrate 100 in an upward direction. However, embodiments of the inventive concept are not limited thereto. For example, the substrate 100 and the flexible substrate 300 may be separated by various other methods.

[0086] As a result of separating the substrate 100 and the flexible substrate 300 , a transparent flexible display module DPA is generated.

[0087] The second charge adhesion pattern 220 may remain at the bottom of the separated flexible substrate 300 , and the first charge adhesion pattern 210 may remain at the top surface of the substrate 100 .

[0088] Since the second charge adhesion pattern 220 is substantially transparent, the second charge adhesion pattern 220 may not substantially affect the light transmittance of the transparent flexible display module DPA.

[0089] Thereafter, the transparent flexible display module DPA is cut to form a plurality of display panels DP. Thereafter, a transparent flexible display device may be manufactured by using the display panels DP.

[0090] Fig. 9 It shows that according to Figure 7 FIG. 1 is a photograph of a bottom surface of a transparent flexible display module DPA according to an embodiment of the present inventive concept.

[0091] Reference Figure 7 and Fig. 9, when the second charge adhesion pattern 220 and the first charge adhesion pattern 210 are separated, a portion of the surface of the second charge adhesion pattern 220 may also be removed. Accordingly, the bottom surface of the second charge adhesion pattern 220 may have a concave-convex shape. The concave-convex shape of the second charge adhesion pattern 220 may be randomly distributed on the plane. Moreover, the concave-convex shape of the second charge adhesion pattern 220 may have a height T1 of about 1 nanometer or less.

[0092] By the manufacturing method of the flexible display device according to the embodiment of the inventive concept, since the adhesion force between the substrate 100 and the flexible substrate 300 is relatively lower than the adhesion force between the first charge adhesion pattern 210 and the second charge adhesion pattern 220, the substrate 100 and the flexible substrate 300 can be easily separated without performing an additional process.

[0093] When a process of weakening the adhesive force between the substrate 100 and the flexible substrate 300 by irradiating laser from below is additionally performed, the bottom surface of the flexible substrate 300 is burned or becomes yellow (yellowing, yellow index increases) due to laser irradiation in addition to the additional process. Therefore, the additional process is not suitable for the transparent flexible display device.

[0094] The method of manufacturing a flexible display device according to an embodiment of the inventive concept can prevent the bottom surface of the flexible substrate 300 from being burned and yellowed by easily separating the substrate 100 from the flexible substrate 300 without laser irradiation, and thus can manufacture a transparent flexible display device with high transmittance.

[0095] Fig. 10A It is shown Figure 7 A plan view of a transparent flexible display module DPA in FIG. Fig. 10B is along Fig. 10A A cross-sectional view taken along line II-II'. Fig. 10B 1 is a cross-sectional view showing a portion of the display panel DP, particularly a portion corresponding to one pixel.

[0096] Reference Fig. 10A and Fig. 10B The transparent flexible display module DPA may include a plurality of display panels DP. The display panels DP may be spaced apart from each other. The display panels DP may be individually cut and used in a display device.

[0097] Reference Fig. 10B , the display unit 400 may include a circuit element layer CL, a display element layer DPL, and an encapsulation layer TFE. Although not shown, the display unit 400 may further include at least one of a touch sensor, an anti-reflection layer, and a window member.

[0098] The circuit element layer CL may include a signal line, a scan line GL, a data line DL, and a power line PL. Also, the circuit element layer CL may include a plurality of transistors and capacitors. Fig. 10B In FIG. 1 , the first transistor T1 is exemplarily described.

[0099] The circuit element layer CL may include a barrier layer BR, an active layer ACT, a gate insulating layer GI, a gate electrode GE, an interlayer insulating layer ILD, input and output electrodes SE and DE, and an intermediate insulating layer VLD.

[0100] The barrier layer BR is disposed on the flexible substrate 300 , and prevents the introduction of foreign substances other than the barrier layer BR.

[0101] Although not shown, the display unit 400 may further include a buffer layer (not shown) disposed on the barrier layer BR. The buffer layer (not shown) improves the coupling force between the flexible substrate 300 and the layer disposed thereon. The buffer layer (not shown) and the barrier layer BR may be selectively provided or omitted.

[0102] The active layer ACT is disposed on the barrier layer BR. The active layer ACT may be used as a channel region of the first transistor T1. The active layer ACT may be selected from amorphous silicon, polycrystalline silicon or metal oxide semiconductor.

[0103] A gate insulating layer GI may be disposed on the active layer ACT. The gate insulating layer GI may insulate the gate electrode GE from the active layer ACT.

[0104] The gate electrode GE may be disposed on the gate insulating layer GI. The gate electrode GE may overlap the active layer ACT.

[0105] A first conductive layer (not shown) providing a signal line may be disposed on the same layer as the gate electrode GE.

[0106] The interlayer insulating layer ILD is disposed on the gate electrode GE. The interlayer insulating layer ILD electrically insulates the gate electrode GE from the input electrode SE and the output electrode DE. The interlayer insulating layer ILD may include an inorganic material. The inorganic material may include silicon nitride, silicon oxynitride, silicon oxide, and the like.

[0107] The input electrode SE and the output electrode DE are disposed on the interlayer insulating layer ILD. The input electrode SE and the output electrode DE may be electrically connected to the active layer ACT through first and second contact holes CH1 and CH2 defined in the interlayer insulating layer ILD and the gate insulating layer GI, respectively.

[0108] A second conductive layer (not shown) providing a signal line may be disposed on the same layer as the input electrode SE and the output electrode DE.

[0109] Although the display panel DP has a top gate structure in which the gate electrode GE is disposed on the active layer ACT in an embodiment of the inventive concept, in another embodiment, the display panel DP may have a bottom gate structure in which the gate electrode GE is disposed under the active layer ACT.

[0110] The intermediate insulating layer VLD is arranged on the input electrode SE and the output electrode DE. The intermediate insulating layer VLD may provide a planarized surface. The intermediate insulating layer VLD may include an organic material. The organic material may include at least one of an acrylic resin, a methacrylic resin, a polyisoprene resin, a vinyl resin, an epoxy resin, a urethane resin, a cellulose resin, a siloxane resin, a polyimide resin, a polyamide resin, and a perylene resin.

[0111] The display element layer DPL is arranged on the intermediate insulating layer VLD. The display element layer DPL may include a pixel defining layer PDL and a display element. In an embodiment of the present inventive concept, the display element may be an organic light emitting diode OLED. The organic light emitting diode OLED includes a first electrode AE, a hole control layer HCL, an emission layer EML, an electron control layer ECL and a second electrode CE.

[0112] The pixel defining layer PDL may include an organic material. The first electrode AE ​​is arranged on the intermediate insulating layer VLD. The first electrode AE ​​is connected to the output electrode DE through a third contact hole CH3 passing through the intermediate insulating layer VLD. A first opening OP1 is defined in the pixel defining layer PDL. The first opening OP1 of the pixel defining layer PDL exposes at least a portion of the first electrode AE.

[0113] The transparent flexible display panel DP may be defined with a light emitting region PXA and a non-light emitting region NPXA disposed adjacent to the light emitting region PXA. The non-light emitting region NPXA may surround the light emitting region PXA. In an embodiment, the light emitting region PXA may be defined corresponding to a portion of the first electrode AE ​​exposed by the first opening OP1.

[0114] The hole control layer HCL may be commonly disposed on the light emitting area PXA and the non-light emitting area NPXA. Although not separately shown, a common layer such as the hole control layer HCL may be commonly disposed on a plurality of organic light emitting diodes OLED.

[0115] The light-emitting layer EML is arranged on the hole control layer HCL. The light-emitting layer EML may be arranged on a region corresponding to the first opening OP1. That is, the light-emitting layer EML may be divided and provided on each of the plurality of organic light-emitting diodes OLED. The light-emitting layer EML may include an organic material and / or an inorganic material. Although a patterned light-emitting layer EML is exemplarily shown in the embodiment, the light-emitting layer EML may be commonly arranged on the plurality of organic light-emitting diodes OLED. Here, the light-emitting layer EML may generate white light. Moreover, the light-emitting layer EML may have a multilayer structure.

[0116] The electronic control layer ECL is disposed on the light emitting layer EML. Although not shown separately, the electronic control layer ECL may be commonly disposed on a plurality of organic light emitting diodes OLED.

[0117] The second electrode CE is disposed on the electronic control layer ECL. The second electrode CE is commonly disposed on the plurality of organic light emitting diodes OLED.

[0118] The encapsulation layer TFE seals the display element layer DPL. The encapsulation layer TFE is arranged on the second electrode CE. The encapsulation layer TFE is commonly arranged on a plurality of organic light emitting diodes OLED. In an embodiment, the encapsulation layer TFE directly covers the second electrode CE. In another embodiment of the present inventive concept, a covering layer covering the second electrode CE may also be arranged between the encapsulation layer TFE and the second electrode CE. Here, the encapsulation layer TFE may directly cover the covering layer.

[0119] The encapsulation layer TFE includes at least one inorganic layer (hereinafter referred to as the encapsulation inorganic layer). The encapsulation layer TFE may also include at least one organic layer (hereinafter referred to as the encapsulation organic layer). The encapsulation inorganic layer protects the display element layer DPL from moisture / oxygen, and the encapsulation organic layer protects the display element layer DPL from foreign matter such as dust particles. The encapsulation inorganic layer may include a silicon nitride layer, a silicon oxynitride layer, a silicon oxide layer, a titanium oxide layer, or an aluminum oxide layer. The encapsulation organic layer may include an acrylic-based organic layer. However, embodiments of the inventive concept are not limited thereto.

[0120] Fig.11 and Fig.12 is a cross-sectional view illustrating a manufacturing process for forming a flexible display device according to another embodiment of the inventive concept.

[0121] Fig.11 In another embodiment of the present invention, Figure 4B and Figure 1 0 is a cross-sectional view of the process corresponding to operation S40 in FIG.

[0122] Reference Fig.11 , will be with Figure 1The processes corresponding to operation S10 to operation S40 in FIG. 1 are described, and the processes not described will follow Figures 1 to 4B Related description in .

[0123] Reference Fig.11 , a first charge sticking pattern 230 and a second charge sticking pattern 240 are formed on the substrate 100. The first charge sticking pattern 230 has a first charge, and the second charge sticking pattern 240 has a second charge.

[0124] The first charge adhesion pattern 230 has a lower first charge adhesion pattern 231 and an upper first charge adhesion pattern 233. The second charge adhesion pattern 240 has a lower second charge adhesion pattern 241 and an upper second charge adhesion pattern 243.

[0125] The lower first charge adhesion pattern 231, the lower second charge adhesion pattern 241, the upper first charge adhesion pattern 233, and the upper second charge adhesion pattern 243 may be sequentially stacked on the substrate 100. The lower first charge adhesion pattern 231, the lower second charge adhesion pattern 241, the upper first charge adhesion pattern 233, and the upper second charge adhesion pattern 243 may be formed by performing a process of coating, cleaning, and drying each of the lower first charge adhesion layer, the lower second charge adhesion layer, the upper first charge adhesion layer, and the upper second charge adhesion layer on the substrate 100, and then removing the edge of each of the four layers.

[0126] Despite Fig.11 exemplarily illustrates the first charge adhesion pattern 230 and the second charge adhesion pattern 240 each having two layers, but each of the first charge adhesion pattern 230 and the second charge adhesion pattern 240 may have three layers or more.

[0127] In an embodiment of the present inventive concept, the lower first charge adhesion pattern 231 may include graphene oxide, the lower second charge adhesion pattern 241 may include montmorillonite, molybdenum disulfide, or hexagonal boron nitride (hBN), the upper first charge adhesion pattern 233 may include polyethyleneimine (PEI), and the upper second charge adhesion pattern 243 may include montmorillonite, molybdenum disulfide, or hexagonal boron nitride (hBN).

[0128] Fig.12 It is to show that the embodiment of the present invention is performed in accordance with Figure 1 2 is a cross-sectional view of a process state corresponding to operation S50 to operation S70 in FIG.

[0129] When executed with Figure 1During the process corresponding to operation S70 in step S71, the substrate 100 and the flexible substrate 300 may be separated so that at least the lower first charge sticking pattern 231 remains on the substrate 100, and at least one of the lower second charge sticking pattern 241, the upper first charge sticking pattern 233, and the upper second charge sticking pattern 243 remains on the flexible substrate 300. Fig.12 , a state in which the upper first charge adhesion pattern 233 and the upper second charge adhesion pattern 243 remain on the flexible substrate 300 is exemplarily shown. However, embodiments of the inventive concept are not limited thereto. For example, the upper first charge adhesion pattern 233, the upper second charge adhesion pattern 243, and the lower second charge adhesion pattern 241 may remain on the flexible substrate 300.

[0130] Polyethyleneimine (PEI) has a transmittance greater than that of graphene oxide.

[0131] In reference Fig.11 and Fig.12 In the described embodiment of the inventive concept, one layer of the plurality of first charge adhesion patterns 230 disposed adjacent to the flexible substrate 300 includes polyethyleneimine (PEI), and the other layer disposed adjacent to the substrate 100 includes graphene oxide. Thereafter, when the substrate 100 is separated from the flexible substrate 300, the layer including polyethyleneimine (PEI) among the plurality of first charge adhesion patterns 230 remains on the flexible substrate 300, and the layer including graphene oxide is removed together with the substrate 100. Accordingly, when the plurality of first charge adhesion patterns 230 and the second charge adhesion patterns 240 are used, adhesion reliability during the manufacturing process can be improved as graphene oxide is used, and at the same time, a transparent flexible display device having a higher transmittance is manufactured.

[0132] According to the method for manufacturing a flexible display device according to an embodiment of the inventive concept, a bottom surface of a flexible substrate can be prevented from being burned and yellowed by easily separating a substrate and a flexible substrate without laser irradiation, thereby manufacturing a transparent flexible display device with higher transmittance.

[0133] By the method of manufacturing a flexible display device according to an embodiment of the inventive concept, since the substrate and the flexible substrate directly contact each other in the peripheral region to have high adhesive force, the substrate and the flexible substrate may not be easily separated in a process of forming a display unit.

[0134] Although exemplary embodiments of the present invention have been described, it should be understood that the present invention should not be limited to these exemplary embodiments, but can be variously changed and modified by one of ordinary skill in the art within the spirit and scope of the present invention as claimed.

[0135] Therefore, the actual protection scope of the present invention should be determined by the technical scope of the appended claims.

Claims

1. A method for manufacturing a flexible display device, the method comprising: preparing a substrate; forming a first charge adhesion layer having a first charge on the substrate; forming a second charge bonding layer having a second charge on the first charge bonding layer; forming a first charge adhesion pattern and a second charge adhesion pattern by removing an edge of each of the first charge adhesion layer and the second charge adhesion layer, wherein a portion of a top surface of the substrate is exposed by forming the first charge adhesion pattern and the second charge adhesion pattern; forming a flexible substrate on the substrate having the first charge adhesion pattern and the second charge adhesion pattern formed thereon, wherein, by forming the flexible substrate, the flexible substrate is in direct contact with the portion of the substrate exposed by the first charge adhesion pattern and the second charge adhesion pattern; forming a display unit on the flexible substrate; cutting the substrate, the first charge adhesion pattern, the second charge adhesion pattern, the flexible substrate, and the display unit along a cutting line; and separating the substrate and the flexible substrate without using laser irradiation so that the second charge adhesion layer remains on the flexible substrate by separating the substrate from the flexible substrate, and Wherein, the second charge bonding layer is transparent.

2. The method of claim 1, wherein: The first charge adhesion layer includes graphene oxide.

3. The method of claim 1, wherein: The second charge adhesion layer includes montmorillonite, molybdenum disulfide or hexagonal boron nitride.

4. The method of claim 1, wherein: The first charge adhesion pattern and the second charge adhesion pattern are formed by removing a portion of each of the first charge adhesion layer and the second charge adhesion layer by spraying a gas in a plasma state of a mixture of nitrogen gas and air.

5. The method of claim 1, wherein: The flexible substrate is formed by coating a polymer material on an area larger than an area occupied by the first charge adhesion pattern and the second charge adhesion pattern.

6. The method of claim 1, wherein: The cutting line is defined to overlap the first charge adhesion pattern and the second charge adhesion pattern on a plane.

7. The method of claim 1, wherein: The cutting line has a closed loop shape on a plane and is defined along an edge of each of the first charge adhesion pattern and the second charge adhesion pattern.

8. A method for manufacturing a flexible display device, the method comprising: preparing a substrate; forming a lower first charge adhesion layer having a first charge on the substrate; forming a lower second charge bonding layer having a second charge opposite to the first charge on the lower first charge bonding layer; forming an upper first charge bonding layer having the first charge on the lower second charge bonding layer; forming an upper second charge bonding layer having the second charge on the upper first charge bonding layer; forming a lower first charge adhesion pattern, a lower second charge adhesion pattern, an upper first charge adhesion pattern, and an upper second charge adhesion pattern by removing an edge of each of the lower first charge adhesion layer, the lower second charge adhesion layer, the upper first charge adhesion layer, and the upper second charge adhesion layer, wherein a portion of a top surface of the substrate is exposed by forming the lower first charge adhesion pattern, the lower second charge adhesion pattern, the upper first charge adhesion pattern, and the upper second charge adhesion pattern; forming a flexible substrate on the substrate on which the lower first charge adhesion pattern, the lower second charge adhesion pattern, the upper first charge adhesion pattern, and the upper second charge adhesion pattern are formed, wherein, by forming the flexible substrate, the flexible substrate is in direct contact with the portion of the substrate exposed by the lower first charge adhesion pattern, the lower second charge adhesion pattern, the upper first charge adhesion pattern, and the upper second charge adhesion pattern; forming a display unit on the flexible substrate; cutting the substrate, the lower first charge adhesion pattern, the lower second charge adhesion pattern, the upper first charge adhesion pattern, the upper second charge adhesion pattern, the flexible substrate, and the display unit along a cutting line; and separating the substrate and the flexible substrate without using laser irradiation so that the upper first charge adhesion pattern and the upper second charge adhesion pattern remain on the flexible substrate by separating the substrate from the flexible substrate, and Wherein, the upper first charge bonding pattern and the upper second charge bonding pattern are transparent.

9. The method of claim 8, wherein: The lower first charge adhesion layer includes graphene oxide, and the upper first charge adhesion layer includes polyethyleneimine.

10. The method of claim 8, wherein: Each of the lower second charge bonding layer and the upper second charge bonding layer includes montmorillonite, molybdenum disulfide, or hexagonal boron nitride.

11. A flexible display device, comprising: Flexible substrate; a circuit element layer, the circuit element layer being arranged on the flexible substrate; a display element layer, the display element layer being arranged on the circuit element layer and comprising an organic light emitting diode; an encapsulation layer, the encapsulation layer being arranged on the display element layer to seal the display element layer; as well as a charge adhesion layer, the charge adhesion layer being in contact with the lower surface of the flexible substrate, wherein the charge bonding layer has charges and comprises montmorillonite, molybdenum disulfide or hexagonal boron nitride, and The charge adhesion layer is transparent, has a bottom surface with a concavo-convex shape, and the concavo-convex shape of the bottom surface of the charge adhesion layer has a height of 1 nm or less.

12. The flexible display device according to claim 11, wherein: The concavo-convex shapes of the bottom surface of the charge adhesion layer are randomly distributed.

13. The flexible display device according to claim 11, further comprising: a lower charge bonding layer, the lower charge bonding layer being in contact with a lower surface of the charge bonding layer, Wherein, the lower charge binding layer is transparent and comprises polyethyleneimine.

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