阅读说明：本技术 喷墨印刷装置、偶极子对准方法及显示设备制造方法 (Inkjet printing apparatus, dipole alignment method, and display device manufacturing method ) 是由 郑兴铁 李炳哲 许明洙 郭珍午 李度宪 于 2019-04-08 设计创作，主要内容包括：提供了喷墨印刷装置、偶极子对准方法以及显示设备制造方法。根据实施方式的显示设备的喷墨印刷装置包括：台；印刷头单元,位于台上方；以及电场产生构件,向台和印刷头单元之间的空间提供电场。(Provided are an inkjet printing apparatus, a dipole alignment method, and a display device manufacturing method. The inkjet printing apparatus of a display device according to an embodiment includes: a stage; a print head unit located above the table; and an electric field generating member supplying an electric field to a space between the stage and the print head unit.)

1. An inkjet printing apparatus comprising:

a stage;

a print head unit located above the table; and

an electric field generating member supplying an electric field to a space between the stage and the print head unit.

2. The apparatus of claim 1, wherein the print head unit comprises a print head and a nozzle connected to the print head and ejecting ink comprising a dipole.

3. The apparatus as claimed in claim 2, wherein the electric field generating member comprises an antenna element including an antenna pattern.

4. The apparatus of claim 3, wherein the antenna unit is disposed on the stage and the print head unit.

5. The apparatus of claim 4, wherein the antenna unit generates a vertical electric field in the space between the stage and the print head unit.

6. The apparatus of claim 4, further comprising a substrate mounting member disposed on the antenna element,

wherein the antenna unit is disposed on the stage and surrounded between the stage and the substrate mounting member.

7. The apparatus of claim 3, wherein the antenna unit is disposed on one side of the table.

8. The apparatus of claim 7, wherein the antenna unit generates a horizontal electric field in the space between the stage and the print head unit.

9. The apparatus of claim 2, wherein the dipole comprises a light emitting element.

10. The apparatus of claim 1, further comprising:

a probe unit; and

a probe driver driving the probe unit.

11. A dipole alignment method, comprising:

under the state that an electric field is generated above a target substrate, jetting ink containing dipoles onto the target substrate through a region where the electric field is generated; and

dropping the dipoles on the target substrate.

12. The method of claim 11, wherein the electric field is provided by an antenna element comprising the antenna pattern.

13. The method of claim 11, wherein ejecting the ink comprises aligning an orientation direction of the dipoles by the electric field.

14. The method of claim 11, wherein the target substrate comprises a first electrode and a second electrode, and the dipole is dropped onto the first electrode and the second electrode while the dipole is dropped.

15. The method of claim 14, wherein dropping the dipole comprises applying alternating current power to the first electrode and the second electrode.

16. The method of claim 11, wherein jetting the ink onto the target substrate is performed using an inkjet printing device.

17. The method of claim 16, wherein the inkjet printing device comprises:

a stage;

a print head unit located above the table; and

an electric field generating member supplying an electric field to a space between the stage and the print head unit.

18. A display device manufacturing method, comprising:

preparing a base layer on which a first electrode and a second electrode are formed;

ejecting ink containing a light emitting element onto the base layer through a region where the electric field is generated in a state where the electric field is generated above the base layer; and

dropping the light emitting element between the first electrode and the second electrode.

19. The method of claim 18, wherein the base layer comprises a plurality of pixels, the first and second electrodes are disposed in each of the pixels, and

the light emitting element is dropped between the first electrode and the second electrode in each of the pixels.

20. The method of claim 18, wherein ejecting the ink further comprises aligning an orientation direction of the light emitting elements by the electric field.

Technical Field

The present disclosure relates to an inkjet printing apparatus, a dipole alignment method, and a display device manufacturing method.

Background

With the development of multimedia, display devices become more and more important. Accordingly, various types of display devices, such as organic light emitting displays and liquid crystal displays, are being used.

The display device is a device for displaying an image, and includes a display panel such as an organic light emitting display panel or a liquid crystal display panel. As the light emitting display panel, the display panel may include a light emitting element, and examples of the light emitting element include a Light Emitting Diode (LED), such as an Organic Light Emitting Diode (OLED) using an organic material as a fluorescent material and an inorganic LED using an inorganic material as a fluorescent material.

The OLED uses an organic material as a fluorescent material of a light emitting element. Therefore, the manufacturing process is simple, and the display element can have flexible properties. However, organic materials are known to be susceptible to high temperature driving environments and to have relatively low blue light efficiency.

On the other hand, an inorganic LED using an inorganic semiconductor as a fluorescent material is durable even in a high-temperature environment and has higher blue light efficiency than an OLED. Further, an alignment method using a dielectrophoresis method is being developed for a manufacturing process indicated as a limitation of the conventional inorganic LED. However, even if the dielectrophoresis method is used, it is not easy to align all the inorganic LEDs having random orientation directions, and defects due to misalignment may occur.

Disclosure of Invention

Technical problem

Aspects of the present disclosure provide an inkjet printing apparatus that can easily align the orientation direction of a dipole.

Aspects of the present disclosure also provide a dipole alignment method with improved alignment accuracy.

Aspects of the present disclosure also provide a display device manufacturing method having improved alignment accuracy of light emitting elements.

However, aspects of the present disclosure are not limited to the aspects set forth herein. The foregoing and other aspects of the present disclosure will become more readily apparent to those of ordinary skill in the art to which the present disclosure pertains by reference to the detailed description of the present disclosure given below.

Technical scheme

According to an exemplary embodiment of the present disclosure, an inkjet printing apparatus includes: a stage; a print head unit located above the table; and an electric field generating member supplying an electric field to a space between the stage and the print head unit.

The print head unit may include a print head and a nozzle connected to the print head and ejecting ink containing dipoles.

The electric field generating member may include an antenna element including an antenna pattern.

The antenna unit may be provided on the stage and the print head unit.

The antenna unit may generate a vertical electric field in the space between the stage and the print head unit.

The inkjet printing apparatus may further include a substrate mounting member disposed on the antenna unit, wherein the antenna unit may be disposed on the stage and surrounded between the stage and the substrate mounting member.

The antenna unit may be disposed on one side of the table.

The antenna unit may generate a horizontal electric field in the space between the stage and the print head unit.

The dipole may include a light emitting element.

The inkjet printing apparatus may further include a probe unit and a probe driver driving the probe unit.

According to an exemplary embodiment of the present disclosure, a dipole alignment method includes: under the state that an electric field is generated above a target substrate, ink containing dipoles is jetted onto the target substrate through a region where the electric field is generated; and landing the dipole on the target substrate.

The electric field may be provided by an antenna element comprising an antenna pattern.

Ejecting the ink may include aligning the orientation direction of the dipoles by an electric field.

The target substrate may include a first electrode and a second electrode, and the dipole may be dropped onto the first electrode and the second electrode when the dipole is dropped.

Dropping the dipole may include applying alternating current power to the first electrode and the second electrode.

The jetting of ink onto the target substrate may be performed using an inkjet printing device.

The inkjet printing apparatus may include: a stage; a print head unit located above the table; and an electric field generating member supplying an electric field to a space between the stage and the print head unit.

According to an exemplary embodiment of the present disclosure, a display device manufacturing method includes: preparing a base layer on which a first electrode and a second electrode are formed; ejecting ink containing a light emitting element onto the base layer through a region where an electric field is generated in a state where the electric field is generated above the base layer; and dropping the light emitting element between the first electrode and the second electrode.

The base layer may include a plurality of pixels, a first electrode and a second electrode are disposed in each of the pixels, and the light emitting element may be interposed between the first electrode and the second electrode in each of the pixels.

Ejecting the ink may also include aligning the orientation direction of the light emitting elements by an electric field.

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

Advantageous effects

According to the embodiment, alignment accuracy can be improved while easily aligning the orientation direction of the dipoles. In addition, since the alignment accuracy of the light emitting elements is improved, display defects of the display device can be reduced.

However, the effects of the embodiments are not limited to those set forth herein. The above and other effects of the embodiments will become more apparent to those skilled in the art to which the embodiments pertain by referring to the detailed description of the present disclosure given below.

Drawings

Fig. 1 is a perspective view of an inkjet printing apparatus according to an embodiment;

FIG. 2 is a partial cross-sectional view of an inkjet printing apparatus according to an embodiment;

FIG. 3 is a partial plan view of an inkjet printing apparatus according to an embodiment;

fig. 4a and 4b are partial sectional views illustrating an orientation direction of a dipole in ink according to an operation of an antenna unit in an inkjet printing apparatus according to an embodiment;

FIG. 5 is a partial plan view of an inkjet printing apparatus according to another embodiment;

FIG. 6 is a partial cross-sectional view showing the orientation direction of dipoles in an ink according to the operation of an antenna unit in the inkjet printing apparatus of FIG. 5;

fig. 7a to 7e are partial plan views of an inkjet printing device according to various embodiments;

FIG. 8 is a partial plan view of an inkjet printing apparatus according to another embodiment;

fig. 9 is a partial sectional view showing an orientation direction of dipoles in ink according to an operation of an antenna unit in the inkjet printing apparatus of fig. 8;

fig. 10 is a flowchart illustrating a dipole alignment method according to an embodiment;

fig. 11 to 14 are sectional views respectively showing operations in the dipole alignment method according to the embodiment;

fig. 15 is a plan view of a display device manufactured using a method according to an embodiment;

FIG. 16 is a cross-sectional view taken along line I-I ', line II-II ', and line III-III ' of FIG. 15;

fig. 17 is a schematic view of a light-emitting element according to an embodiment; and

fig. 18 and 19 are sectional views respectively showing operations in the display device manufacturing method according to the embodiment.

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

It will also be understood that when a layer is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like elements throughout the specification.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element discussed below could be termed a second element without departing from the teachings of the present invention. Similarly, a second element may also be referred to as a first element.

Hereinafter, specific embodiments will be described with reference to the accompanying drawings.

Fig. 1 is a perspective view of an inkjet printing apparatus according to an embodiment. Fig. 2 is a partial cross-sectional view of an inkjet printing apparatus according to an embodiment. Fig. 3 is a partial plan view of an inkjet printing apparatus according to an embodiment. In the figures, a first direction D1, a second direction D2 and a third direction D3 are defined. The first direction D1 and the second direction D2 lie in one plane and are orthogonal to each other, and the third direction D3 is perpendicular to each of the first direction D1 and the second direction D2.

Referring to fig. 1 to 3, an inkjet printing apparatus 1000 according to an embodiment includes a stage 710 and a print head unit 800, the print head unit 800 being located above the stage 710 in a third direction D3. The inkjet printing device 1000 may further include a base frame 610, an electric field generating member, a substrate mounting member 730, and a head support 620.

The stage 710 provides a space in which a target substrate SUB is disposed. The stage 710 may be disposed on the base frame 610.

The electric field generating member is disposed on the stage 710. The electric field generating member is disposed on the rear surface of the target substrate SUB and generates an electric field thereabove (third direction D3), that is, in a space where the printing process is performed. In the drawing, the antenna unit 720 is shown as an example of the electric field generating member. However, the electric field generating member is not limited to the antenna unit 720, and a plurality of electrodes or various other members capable of generating an electric field may be applied.

The antenna unit 720 may include a base substrate 721, an antenna pattern 722 disposed on the base substrate 721, and an insulating layer 723 disposed on the antenna pattern 722.

The base substrate 721 may be a printed circuit board or a flexible circuit board, or may be an insulating substrate such as polyimide.

The antenna pattern 722 generates an electric field. Specifically, when a current flows in response to the power supplied to the antenna pattern 722, an electromagnetic wave may be generated, thereby generating a vertical electric field having a horizontal equipotential surface. The generated electric field may control the orientation direction of the dipoles 31 included in the ink 30. This will be described in detail later.

As shown in fig. 3, when the shape of the antenna pattern 722 is spread substantially uniformly in a plan view, the planar shape of the antenna pattern 722 is advantageous in generating a uniform electric field. The antenna pattern 722 may have a size and shape that allows it to cover the entire target substrate SUB so as to generate an electric field over the entire target substrate SUB. In a rectangular target substrate SUB, the corners may have different characteristics than other areas. To compensate for this, the shape of the antenna pattern 722 may be designed such that the electric field at the corners of the target substrate SUB is equal to or greater than the electric field in other regions. For example, the antenna pattern 722 may be formed in a shape corresponding to the corners of the target substrate SUB, or the density of the antenna pattern 722 at the corners may be increased so as not to reduce the strength of the electric field in these regions.

The planar shape of the antenna pattern 722 may be, but is not limited to, a closed loop shape, a plurality of closed loop shapes, an open loop shape, a rectangular shape, a polygonal shape, a circular shape, a spiral shape wound around the center, a coil shape, or a combination thereof.

The antenna pattern 722 may be made of a conductive material such as silver (Ag) or copper (Cu).

A cover layer 723 covers the antenna pattern 722. The capping layer 723 may include an inorganic insulating layer such as a silicon oxide layer, a silicon nitride layer, or a silicon oxynitride layer, or may include an organic insulating material. At least one of the base substrate 721 and the capping layer 723 may further include a magnetic substance, but the present disclosure is not limited thereto.

The substrate mounting member 730 may be disposed on the antenna unit 720. The substrate mounting member 730 may cover the electric field generating member. For a printing process, the target substrate SUB may be mounted on the substrate mounting member 730. A substrate aligner 740 may be mounted on the substrate mounting member 730 to align the target substrate SUB. The substrate mounting member 730 may be made of quartz or a ceramic material and provided in the form of an electrostatic chuck, but the present disclosure is not limited thereto.

An edge portion of the substrate mounting member 730 may contact the stage 710, and thus, the electric field generating member may be surrounded by the substrate mounting member 730 and the stage 710. In some embodiments, the substrate mounting member 730 may be manufactured integrally with the stage 710. When a unit providing a space in which the target substrate SUB is mounted is defined as the stage unit 700, the stage unit 700 may further include an antenna unit 720 and/or a substrate mounting member 730 in addition to the stage 710. In this case, the antenna unit 720 may be understood as being built in the station unit 700.

The entire planar shape of the stage unit 700 may follow the planar shape of the target substrate SUB. For example, when the target substrate SUB is rectangular, the overall shape of the stage unit 700 may be a rectangular shape. When the target substrate SUB is circular, the overall shape of the stage unit 700 may be a circular shape. In the drawings, the stage unit 700 is illustrated to have a rectangular shape, the long sides of which are disposed in the first direction D1, and the short sides of which are disposed in the second direction D2.

The print head unit 800 is used to print the ink 30 on the target substrate SUB. The inkjet printing apparatus 1000 may further include an ink supply portion such as an ink cartridge, and the ink 30 supplied from the ink supply portion may be ejected (jetted) toward the target substrate SUB by the print head unit 800. The ink 30 may be provided in a solution state. The ink 30 may comprise, for example, a solvent 32 (see fig. 4a) and a plurality of dipoles 31 (see fig. 4a) comprised in the solvent 32. The solvent 32 may be acetone, water, alcohol, toluene, or the like. The solvent 32 may be a material that evaporates or volatilizes at room temperature or by heating. Dipole 31 may be dispersed in solvent 32. The dipole 31 may be a solid material that is eventually left on the target substrate SUB after the solvent 32 is removed.

Each of the dipoles 31 may be an object including one end having a first polarity and the other end having a second polarity different from the first polarity. For example, one end of each dipole 31 may have a positive polarity, and the other end of each dipole 31 may have a negative polarity. When the dipoles 31 are placed in the electric field generated by the antenna unit 720, each dipole 31 having different polarities at both ends thereof may receive electric power (attractive force and repulsive force). Thus, the orientation direction of the dipole 31 can be controlled.

Each of the dipoles 31 may extend in one direction. The dipoles 31 may be shaped like nanorods, nanowires, nanotubes, etc. As the dipoles 31 included in the ink 30 according to the embodiment, semiconductor nanorods each having one end doped with impurities of a first conductive type (e.g., p-type) and the other end doped with impurities of a second conductive type (e.g., n-type) may be applied.

The print head unit 800 is disposed above the substrate mounting member 730. The print head unit 800 may be mounted on the head support 620 and spaced apart from the substrate mounting member 730 by a predetermined distance. The head support 620 may include a horizontal support portion 621 extending in a horizontal direction and a vertical support portion 622 connected to the horizontal support portion 621 and extending in a third direction D3 as a vertical direction. The direction in which the horizontal support portion 621 extends may be the same as the first direction D1, which is the long side direction of the table unit 700. One end of the vertical support portion 622 may be placed on the base frame 610. The print head unit 800 may be mounted on the horizontal support portion 621 of the head support 620.

The distance between the print head unit 800 and the substrate mounting member 730 may be adjusted by the height of the head support 620. The distance between the print head unit 800 and the substrate mounting member 730 may be adjusted within a range that allows the print head unit 800 to be spaced apart from the target substrate SUB by a certain distance in order to secure a processing space when the target substrate SUB is mounted on the substrate mounting member 730.

The print head unit 800 may include a print head 810 and a plurality of nozzles 820 located on a bottom surface of the print head 810. The print head 810 may extend in a direction. The direction in which the print head 810 extends may be the same as the direction in which the horizontal support portion 621 of the head support 620 extends. That is, the direction in which the print head 810 extends may be a first direction D1 that is a longitudinal direction of the stage unit 700. The print head 810 may include an inner tube 811 formed along an extending direction thereof. The nozzles 820 may be arranged along the extension direction of the print head 810. The nozzles 820 may be arranged in one or more rows. In an embodiment, the number of nozzles 820 included in one printhead unit 800 may be, but is not limited to, 128 to 1800.

Each nozzle 820 may be connected to an inner tube 811 of the printhead 810. The ink 30 may be supplied to the inner tube 811 of the print head 810, and the supplied ink 30 may flow along the inner tube 811 and then be ejected through each nozzle 820. The ink 30 ejected through the nozzle 820 may be supplied to the upper surface of the target substrate SUB. The amount of ink 30 ejected through the nozzles 820 may be adjusted according to the voltage applied to each nozzle 820. In an embodiment, the individual shot size of each nozzle 820 may be, but is not limited to, 1 to 50 picoliters (pl).

Although one print head unit 800 is shown in the drawings, the present disclosure is not limited thereto. For example, in the case of a process of providing a plurality of inks 30 to the target substrate SUB, the same number of print head units 800 as the number of types of inks 30 may be provided.

Inkjet printing apparatus 1000 may also include moving parts that move printhead unit 800 and/or stage unit 700.

The print head moving part of the moving print head unit 800 may include a first horizontal moving part 631, a second horizontal moving part 633, and a vertical moving part 632. The first horizontal moving part 631 may move the print head unit 800 on the horizontal support part 621 in the first direction D1, and the second horizontal moving part 633 may move the vertical support part 622 in the second direction D2 to move the print head unit 800 mounted on the head support 620 in the second direction D2. By the horizontal movement of the first and second horizontal moving parts 631 and 633, the ink 30 can be ejected to the entire area of the target substrate SUB even if the area of the print head unit 800 is smaller than that of the target substrate SUB. The first horizontal moving part 631 may be mounted on the horizontal supporting part 621, and the second horizontal moving part 633 may be mounted on the base frame 610. The vertical moving portion 632 on the horizontal support portion 621 can adjust the distance between the print head unit 800 and the target substrate SUB by raising and lowering the position of the print head unit 800 in the vertical direction.

The station moving part 635 of the mobile station unit 700 may move the station unit 700 in the second direction D2. The stage moving part 635 may be mounted on the base frame 610. When the stage moving part 635 is present, the second horizontal moving part 633 of the print head moving part may be omitted. That is, the print head unit 800 may reciprocate in the first direction D1, and the stage unit 700 may move in the second direction D2 to perform a printing process on the entire area of the target substrate SUB.

The inkjet printing apparatus 1000 may further include probe devices 910 and 920. The probe devices 910 and 920 may include probe units 911 and 921 and probe drivers 912 and 922. The probe drivers 912 and 922 may move the probe units 911 and 922 and include a driving cylinder or a driving motor, but the present disclosure is not limited thereto.

The probe units 911 and 921 and the probe drivers 912 and 922 may be disposed on at least one side of the stage unit 700 (or the target substrate SUB). For example, one probe unit and a probe driver driving the probe unit may be disposed adjacent to an outer side of one side of the stage unit 700. However, the present disclosure is not limited thereto, and a plurality of probe units and a plurality of probe drivers may also be provided. In the drawing, two probe units 911 and 921 and two probe drivers 912 and 922 are provided.

As shown in the drawing, the probe apparatus may include a first probe unit 911 and a first probe driver 912 disposed adjacent to an outer side of a first short side of the stage unit 700, and a second probe unit 921 and a second probe driver 922 disposed adjacent to an outer side of a second short side of the stage unit 700.

Each of the first probe cell 911 and the second probe cell 921 may extend in the second direction D2 and include a plurality of probes. The lengths of the first and second probe cells 911 and 921 in the extending direction may cover the entire target substrate SUB. Each of the first and second probe units 911 and 921 may contact an electrode pad of the target substrate SUB and supply a predetermined voltage, for example, an Alternating Current (AC) voltage. The voltage application through the first probe unit 911 and the second probe unit 921 may be performed simultaneously or sequentially. The first and second probe drivers 912 and 922 may be disposed at outer sides of the first and second probe units 911 and 921, and may move the first and second probe units 911 and 921 in a first direction D1 as a horizontal direction and a third direction D3 as a vertical direction. In an embodiment, each of the first probe unit 911 and the second probe unit 921 may be disposed on the stage moving part 635. However, the present disclosure is not limited thereto, and each of the first and second probe units 911 and 921 may also be provided on the base frame 610 or as a separate device.

Fig. 4a and 4b are partial sectional views illustrating an orientation direction of a dipole in ink according to an operation of an antenna unit in an inkjet printing apparatus according to an embodiment. For convenience of description, a detailed sectional structure of the stage unit 700 other than the antenna pattern 722 is not shown in fig. 4a and 4 b.

The dipoles 31 within the ink 30 have random orientation directions when no external force is applied. As shown in fig. 4a, when an electric field is not generated due to no power being applied to the antenna pattern 722 of the antenna unit 720, the directional directions of the dipoles 31 are not aligned in a specific direction from the print head 810 to the target substrate SUB. When the dipole 31 is dropped on the target substrate SUB by a subsequent process of dropping the dipole 31 (for example, by a dielectrophoresis method), the orientation direction may be aligned in a certain direction to some extent. However, when the orientation directions are random in a state where the dipoles 31 are ejected onto the target substrate SUB, misalignment may occur, or it may take a long time to align, because the orientation direction of each dipole 31 is changed to a different degree.

As shown in fig. 4b, when an electric field is generated over the target substrate SUB, the ink 30 may be affected by the electric field from the nozzle 820 of the print head 810 to the target substrate SUB because power is applied to the antenna pattern 722 of the antenna unit 720. When the dipoles 31 in the ink 30 are placed in the electric field, their orientation direction is directed electrically to the direction of the electric field. When the electric field generated by the antenna pattern 722 is a vertical electric field having horizontal equipotential lines IEL as shown in the drawing, the dipoles 31 placed in the electric field may also tend to be substantially oriented in the vertical direction. When the dropping process is performed for the dipoles 31 aligned in a specific direction, the degree of change in the orientation direction of the dipoles 31 becomes similar as compared with the dipoles 31 having random orientation directions. Therefore, the dipoles 31 can be aligned quickly with improved accuracy.

The degree of alignment of the dipoles 31 in the ink 30 jetted onto the substrate before the landing process may be roughly proportional to the time of exposure to the electric field and the magnitude of the electric field. The effective time of exposure of the dipoles 31 to the electric field can be calculated using the following equation.

Effective time H_distance/V_drop,jet

In the above equation, H_distanceRepresents the distance between the print head and the target substrate, and V_drop,jetIndicating the ejection speed of the ink droplets.

The distance between the print head 810 and the target substrate SUB may be 0.3 to 1mm, and the ejection speed of the ink droplets may be 5 to 10 m/s. In this case, the effective time of exposure of the dipoles 31 to the electric field may be 60 to 200 μ s. When the effective time of exposure of the dipoles 31 to the electric field is determined as described above, a desired degree of directional alignment of the dipoles 31 can be ensured by adjusting the magnitude of the electric field, which is another variable with respect to the directional alignment, based on the effective time.

Fig. 5 is a partial plan view of an inkjet printing apparatus according to another embodiment. In fig. 5, a planar arrangement of the stage and the antenna unit is shown, and other components are not shown for convenience of description. Fig. 6 is a partial sectional view illustrating an orientation direction of a dipole in ink according to an operation of an antenna unit in the inkjet printing apparatus of fig. 5.

Referring to fig. 5 and 6, the inkjet printing apparatus according to the current embodiment is different from the embodiment of fig. 1 to 3 in that an antenna unit 750 is disposed on a side of a target substrate SUB (or on a side of a stage unit 701 or a print head 810).

The antenna unit 750 may be disposed outside the short side of the stage unit 701, for example. The antenna unit 750 may be arranged to cover at least the entire short side of the target substrate SUB. In an embodiment, the antenna element 750 may be shaped like a rod extending in the second direction D2.

When the antenna unit 750 receives power, it can generate electromagnetic waves, thereby generating an electric field in a lateral direction toward the target substrate SUB. That is, a horizontal electric field having a vertical equipotential line IEL may be generated between the print head 810 and the target substrate SUB. Therefore, when the ink 30 is ejected from the print head 810, the dipoles 31 included in the ink 30 may be affected by the electric field, and thus their orientation directions may be directed substantially in the horizontal direction. When the dropping process is performed for the dipoles 31 aligned in a specific direction, as described above, the alignment accuracy of the dropped dipoles 31 is improved. Further, when the dropping process is intended to orient the dipoles 31 in the horizontal direction, since the dipoles 31 are aligned in substantially similar orientation directions before the dropping process, the alignment accuracy and speed can be further improved.

The number and arrangement of the antenna elements 750 generating a horizontal electric field are not limited to those shown in fig. 5, but may be variously changed. This will be described in detail with reference to fig. 7a to 7 e.

Fig. 7a to 7e are partial plan views of an inkjet printing apparatus according to various embodiments.

Fig. 7a shows a case where the antenna unit 750 is disposed outside the long side of the stage unit 701. Fig. 7b shows a case where two antenna units 750 are provided outside the long side and the short side of the stage unit 701, respectively. Fig. 7c shows a case where two antenna elements 750 are disposed outside facing sides (short sides in the drawing) of the stage unit 701. Fig. 7d shows a case where three antenna units 750 are disposed outside three sides of the table unit 701, and fig. 7e shows a case where four antenna units 750 are disposed outside four sides of the table unit 701, respectively. As the number of antenna elements 750 generating a horizontal electric field increases, the electric field difference between the regions may be reduced. The electric field in a specific region may be represented as a vector sum of electric fields respectively generated by the plurality of antenna elements 750.

Fig. 8 is a partial plan view of an inkjet printing apparatus according to another embodiment. Fig. 9 is a partial sectional view showing an orientation direction of a dipole in ink according to an operation of an antenna unit in the inkjet printing apparatus of fig. 8.

Referring to fig. 8 and 9, the inkjet printing apparatus according to the current embodiment is different from the previous embodiments in that it includes a first antenna unit 720 generating a vertical electric field and a second antenna unit 750 generating a horizontal electric field. That is, the current embodiment is substantially the same as the structure obtained by adding the antenna unit 750 generating a horizontal electric field as shown in fig. 5 to the inkjet printing apparatus according to the embodiment of fig. 1 to 3.

In the current embodiment, both the vertical electric field of the first antenna unit 720 and the horizontal electric field of the second antenna unit 750 act in the space between the print head 810 and the target substrate SUB to form an electric field according to the vector sum of the vertical electric field and the horizontal electric field. Accordingly, the orientation direction of the dipoles 31 in the ink 30 ejected onto the target substrate SUB can be aligned substantially in the oblique direction between the vertical direction and the horizontal direction. As described above, when the landing process is performed on the dipoles 31 aligned in a specific direction, the orientation direction of the dipoles 31 changes to a similar extent as compared with the dipoles 31 having random orientation directions. Thus, the dipoles 31 can be aligned quickly with improved accuracy.

In the above embodiments, the inkjet printing apparatus has been described as an example of the application apparatus. However, various devices for applying a liquid solution, such as an inkjet injection device, a slot-die coating device, and a slot-die printing device, may be applied as long as the technical spirit is shared.

A dipole alignment method using the inkjet printing apparatus according to the above-described various embodiments will now be described.

Fig. 10 is a flowchart illustrating a dipole alignment method according to an embodiment. Fig. 11 to 14 are sectional views respectively showing operations in the dipole alignment method according to the embodiment.

Referring to fig. 1 to 4 and 10, the dipole alignment method may include providing an inkjet printing apparatus (operation S1), jetting ink containing a dipole onto a target substrate in a state where an electric field has been applied (operation S2), and landing the dipole onto the target substrate (operation S3).

Setting the inkjet printing apparatus (operation S1) is to adjust the operation of the inkjet printing apparatus 1000 according to the target process. For fine adjustment, an inkjet printing test process may be performed on the substrate for inspection, and the set values of the inkjet printing apparatus 1000 may be adjusted according to the result of the process.

Specifically, a substrate for inspection is first prepared. The substrate for inspection may have the same structure as the target substrate SUB, but a bare substrate such as a glass substrate may also be used.

Next, the upper surface of the substrate for inspection is treated with a water repellent agent. The water repellent treatment may be performed by fluorine coating or plasma surface treatment.

Next, the ink 30 containing the dipole 31 is applied to the upper surface of the substrate for inspection using the inkjet printing apparatus 1000, and the droplet amount of each nozzle 820 is measured. The droplet amount of each nozzle 820 can be measured by checking the size of the droplet at the time of ejection and the size of the droplet applied to the substrate using a camera. When the measured droplet amount is different from the reference droplet amount, the voltage of each corresponding nozzle 820 may be adjusted so that the reference droplet amount may be ejected. This checking method may be repeated a plurality of times until each nozzle 820 ejects the correct drop volume.

The provision of the inkjet printing apparatus described above may be omitted (S1).

When the setup of the inkjet printing apparatus 1000 is completed, as shown in fig. 11, the ink 30 containing the dipoles 31 is ejected onto the target substrate SUB (operation S2). A first electrode 21 and a second electrode 22 are formed on a target substrate SUB, and ink 30 is ejected onto the first electrode 21 and the second electrode 22. Here, when a vertical electric field is generated using the antenna unit 720 as described above, the orientation direction of the dipole 31 may be substantially aligned in the vertical direction as the ink 30 passes through the region where the electric field is generated. Although the ink 30 is ejected onto a pair of electrodes in the drawing, a large number of electrode pairs may be formed on the target substrate SUB, and the ink 30 may be ejected to each electrode pair in the same manner as the plurality of nozzles 820 of the print head unit 800 are moved.

Next, landing of the dipole 31 on the target substrate SUB is performed. The dropping of the dipoles 31 may be performed by dielectrophoretic methods. Specifically, as shown in fig. 12, an AC voltage is applied to the first electrode 21 and the second electrode 22. The applied AC voltage may have a voltage of ± (10 to 50) V and a frequency of 10KHz to 1 MHz.

An AC voltage may be applied using the probe apparatus shown in fig. 1. The probe device may also include a signal generator (function generator) and an amplifier for generating an appropriate AC voltage. That is, a signal reflecting the desired AC waveform and frequency may be generated by a signal generator and amplified to an appropriate voltage by an amplifier. Then, an AC voltage may be supplied to each probe of the probe unit.

Each of the first electrode 21 and the second electrode 22 may be connected to an electrode pad disposed on at least one side of the target substrate SUB, and an AC voltage may be applied to the electrode pad through a probe unit of a probe device. When the probe apparatus includes the first probe cell 911 and the second probe cell 921, the electrode pads of the first electrode 21 and the second electrode 22 may also be disposed on both sides of the target substrate SUB. The electrode pad on one side may receive an AC voltage from the first probe cell 911, and the electrode pad on the other side may receive an AC voltage from the second probe cell 921. In this case, the first probe unit 911 and the second probe unit 921 may simultaneously apply the AC voltage, or the first probe unit 911 and the second probe unit 921 may sequentially apply the AC voltage.

When an AC voltage is applied to the first electrode 21 and the second electrode 22, an electric field LEF is generated therebetween, and a dielectrophoretic force acts due to the electric field LEF. The dipoles 31 subjected to the dielectrophoretic force can fall so that both ends thereof contact the first electrode 21 and the second electrode 22 (as shown in fig. 13) with little change in their orientation direction and position. As described above, when the dielectrophoretic force acts, the movement of the dipoles 31 due to the dielectrophoretic force may also be substantially similar, since the orientation directions of the dipoles 31 have been substantially aligned in a particular direction. Therefore, the alignment accuracy of the dropped dipoles 31 can be increased.

Next, as shown in fig. 14, the solvent 32 of the ink 30 may be removed by volatilization or evaporation. Removing the solvent 32 can prevent the flow between the dipole 31 and each electrode and increase the adhesion therebetween. Therefore, the dipoles 31 can be accurately aligned between the first electrode 21 and the second electrode 22.

The inkjet printing apparatus 1000 and the dipole alignment method described above can be used to manufacture a display device including a light emitting element as one kind of dipole 31. This will now be described in detail.

Fig. 15 is a plan view of a display device manufactured using the method according to the embodiment.

Referring to fig. 15, the display device 10 may include a plurality of pixels PX (PX1 to PX 3). The pixels PX may emit light in a specific wavelength band to the outside of the display device 10. The pixels PX may be arranged in a matrix direction. In fig. 15, three pixels PX1 to PX3 that emit different colors are shown as an example. The first pixel PX1 may display red, the second pixel PX2 may display green, and the third pixel PX3 may display blue. The pixels PX may be alternately arranged along rows and columns.

Each pixel PX includes one or more light emitting elements 300. The pixels PX displaying different colors may include light emitting elements 300 emitting different colors. For example, the first pixel PX1 may include a light emitting element 300 emitting red light, the second pixel PX2 may include a light emitting element 300 emitting green light, and the third pixel PX3 may include a light emitting element 300 emitting blue light. However, the present disclosure is not limited thereto. In some cases, pixels displaying different colors may include light emitting elements 300 emitting light of the same color (e.g., blue light), and a wavelength conversion layer or a color filter may be placed on the emission path to achieve the color of each pixel.

Each of the light emitting elements 300 may include a semiconductor having one end doped with p-type (or n-type) and the other end doped with n-type (or p-type) of opposite conductivity type. That is, the light emitting element 300 may be a dipole.

The display device 10 includes a plurality of electrodes 210 and 220. At least a portion of each of the electrodes 210 and 220 may be disposed in each pixel PX and connected to the light emitting element 300, and may transmit an electrical signal such that the light emitting element 300 emits light of a specific color.

In addition, at least a portion of each of the electrodes 210 and 220 may be used to form an electric field in the pixel PX to align the light emitting element 300. As described above, the light emitting elements 300, which are a kind of dipole, may be aligned using a dielectrophoresis method. Here, AC power may be applied to each of the electrodes 210 and 220 to generate an electric field between the first electrode 210 and the second electrode 220.

The electrodes 210 and 220 may include a first electrode 210 and a second electrode 220. In an exemplary embodiment, the first electrode 210 may be a separate pixel electrode disposed in each pixel PX, and the second electrode 220 may be a common electrode commonly connected along the plurality of pixels PX. Any one of the first electrode 210 and the second electrode 220 may be an anode of each light emitting element 300, and the other may be a cathode of each light emitting element 300. However, the present disclosure is not limited thereto, and any one of the first electrode 210 and the second electrode 220 may be a cathode of each light emitting element 300, and the other may be an anode of each light emitting element 300.

Each of the first and second electrodes 210 and 220 may include an electrode rod 210S or 220S extending in a first direction D1 and at least one electrode branch 210B or 220B extending and branching from the electrode rod 210S or 220S in a second direction D2 intersecting the first direction D1.

In particular, the first electrode 210 may include a first electrode rod 210S extending in the first direction D1 and at least one first electrode branch 210B branching from the first electrode rod 210S and extending in the second direction D2. Although not shown in the drawings, one end of the first electrode bar 210S may be connected to the electrode pad and the other end may extend in the first direction D1, but may be electrically isolated between the pixels PX. The electrode pad may contact the probe of the probe apparatus described above, and thus receive AC power.

The first electrode bar 210S of any one pixel may be located on substantially the same straight line as the first electrode bars 210S of the neighboring pixels belonging to the same row (e.g., adjacent in the first direction D1). In other words, both ends of the first electrode bar 210S of one pixel may be terminated at a distance from the pixels PX between the pixels PX, but the first electrode bars 210S of adjacent pixels may be aligned on an extension of the first electrode bar 210S of the one pixel.

Such an arrangement of the first electrode rod 210S may be achieved by forming one rod electrode in a manufacturing process, and then cutting the rod electrode using a laser or the like after performing an alignment process of the light emitting element 300. Accordingly, the first electrode rods 210S respectively disposed in the pixels PX may transmit different electrical signals to their respective first electrode branches 210B, and the first electrode branches 210B respectively disposed in the pixels PX may be individually driven.

The first electrode branch 210B may branch from at least a portion of the first electrode rod 210S and extend in the second direction D2 to terminate at a location spaced apart from the second electrode rod 220S facing the first electrode rod 210S. That is, the first electrode branch 210B may be disposed in each pixel PX such that one end is connected to the first electrode rod 210S and the other end is spaced apart from the second electrode rod 220S. Since the first electrode branch 210B is connected to the first electrode rod 210S electrically isolated in each pixel PX, a different electrical signal may be transmitted to each pixel PX.

In addition, one or more first electrode branches 210B may be disposed in each pixel PX. Although two first electrode branches 210B are provided and the second electrode branch 220B is provided therebetween in fig. 15, the present disclosure is not limited thereto and a greater number of first electrode branches 210B may be provided. In this case, the first electrode branches 210B may be alternately disposed with the plurality of second electrode branches 220B while being spaced apart from the second electrode branches 220B, and the light emitting element 300 may be disposed between the first electrode branches 210B and the second electrode branches 220B. In some embodiments, the second electrode branches 220B may be disposed between the first electrode branches 210B such that each pixel PX has a symmetrical structure with respect to the second electrode branches 220B. However, the present disclosure is not limited thereto.

The second electrode 220 may include a second electrode rod 220S extending in the first direction D1 and spaced apart from the first electrode rod 210S to face the first electrode rod 210S, and at least one second electrode branch 220B branching from the second electrode rod 220S, extending in the second direction D2 and spaced apart from the first electrode branch 210B to face the first electrode branch 210B. The second electrode rod 220S may have an end connected to the electrode pad, as the first electrode rod 210S. The other end of the second electrode bar 220S may extend to a plurality of pixels PX adjacent in the first direction D1. That is, the second electrode bar 220S may be electrically connected between the pixels PX. Accordingly, both ends of the second electrode rod 220S of any one pixel may be connected to the corresponding ends of the second electrode rods 220S of the neighboring pixels between the pixels PX. Accordingly, the same electrical signal may be transmitted to each pixel PX.

The second electrode branch 220B may branch from at least a portion of the second electrode rod 220S and extend in the second direction D2 to terminate at a location spaced apart from the first electrode rod 210S. That is, the second electrode branch 220B may be disposed in each pixel PX such that one end is connected to the second electrode rod 220S and the other end is spaced apart from the first electrode rod 210S. Since the second electrode branch 220B is connected to the second electrode rod 220S electrically connected to each pixel PX, the same electrical signal may be transmitted to each pixel PX.

In addition, the second electrode branch 220B may be spaced apart from the first electrode branch 210B to face the first electrode branch 210B. Here, since the first and second electrode bars 210S and 220S are spaced apart facing each other in opposite directions with respect to the center of each pixel PX, the first and second electrode branches 210B and 220B may extend in opposite directions. In other words, the first electrode branch 210B may extend in one direction of the second direction D2, and the second electrode branch 220B may extend in another direction of the second direction D2. Accordingly, the ends of the branches may be disposed in opposite directions with respect to the center of each pixel PX. However, the present disclosure is not limited thereto, and the first electrode rod 210S and the second electrode rod 220S may also be disposed in the same direction with respect to the center of each pixel PX and spaced apart from each other. In this case, the first and second electrode branches 210B and 220B branched from the first and second electrode rods 210S and 220S, respectively, may extend in the same direction.

Although one second electrode branch 220B is provided in each pixel PX in fig. 15, the present disclosure is not limited thereto, and a greater number of second electrode branches 220B may be provided.

The light emitting element 300 may be aligned between the first electrode branch 210B and the second electrode branch 220B. Specifically, at least some of the light emitting elements 300 may have one end electrically connected to the first electrode branch 210B and the other end electrically connected to the second electrode branch 220B. The light emitting elements 300 are aligned by the dipole alignment method described above, and may have excellent alignment accuracy.

The light emitting elements 300 may be spaced apart from each other in the second direction D2 and aligned substantially parallel to each other. The gap between the light emitting elements 300 is not particularly limited. In some cases, a plurality of light emitting elements 300 may be disposed adjacent to each other to form a group, and other light emitting elements 300 may form a group while being spaced apart from each other by a predetermined distance. Alternatively, the light emitting elements 300 may have a non-uniform density, but may be oriented and aligned in one direction.

The contact electrodes 260 may be disposed on the first and second electrode branches 210B and 220B, respectively. The contact electrodes 260 may extend in the second direction D2 and may be spaced apart from each other in the first direction D1. The contact electrode 260 may include a first contact electrode 261 disposed on the first electrode branch 210B and triggering one end of the optical element 300 and a second contact electrode 262 disposed on the second electrode branch 220B and triggering the other end of the optical element 300.

The first electrode rod 210S and the second electrode rod 220S may be electrically connected to a thin film transistor 120 or a power wiring 161, which will be described later, through the first contact hole CNTD and the second contact hole CNTS. Although the contact holes on the first electrode bar 210S and the second electrode bar 220S are provided in each pixel PX in fig. 15, the present disclosure is not limited thereto. As described above, since the second electrode bar 220S may extend to the adjacent pixel PX and be electrically connected to the adjacent pixel PX, in some embodiments, the second electrode bar 220S may be electrically connected to the thin film transistor through one contact hole.

Fig. 16 is a sectional view taken along line I-I ', line II-II ', and line III-III ' of fig. 15.

Referring to fig. 15 and 16, the display device 10 may include a substrate 110, one or more thin film transistors 120 and 140 disposed on the substrate 110, and electrodes 210 and 220 and a light emitting element 300 disposed over the thin film transistors 120 and 140. The thin film transistor may include a first thin film transistor 120 as a driving transistor transmitting a driving signal. The thin film transistor may further include a second thin film transistor 140. The second thin film transistor 140 may be, but is not limited to, a switching transistor transmitting a data signal. Each of the thin film transistors 120 and 140 may include an active layer, a gate electrode, a source electrode, and a drain electrode. The first electrode 210 may be electrically connected to the drain electrode of the first thin film transistor 120.

More specifically, the substrate 110 may be an insulating substrate with respect to a cross-sectional structure of the display device 10. The substrate 110 may be made of an insulating material such as glass, quartz, or polymer resin. Examples of the polymer material may include Polyethersulfone (PES), Polyacrylate (PA), Polyarylate (PAR), Polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyallylate, Polyimide (PI), Polycarbonate (PC), cellulose triacetate (CAT), Cellulose Acetate Propionate (CAP), and combinations thereof. The substrate 110 may be a rigid substrate or may be a flexible substrate that can be bent, folded, rolled, etc.

A buffer layer 115 may be disposed on the substrate 110. The buffer layer 115 may prevent diffusion of impurity ions, prevent permeation of moisture or external air, and perform a surface planarization function. Buffer layer 115 may include silicon nitride, silicon oxide, or silicon oxynitride.

The semiconductor layer is disposed on the buffer layer 115. The semiconductor layer may include the first active layer 126 of the first thin film transistor 120, the second active layer 146 of the second thin film transistor 140, and the auxiliary layer 163. The semiconductor layer may include polycrystalline silicon, single crystalline silicon, or an oxide semiconductor.

The first gate insulating layer 170 is disposed on the semiconductor layer. The first gate insulating layer 170 covers the semiconductor layer. The first gate insulating layer 170 may function as a gate insulating film of the thin film transistor. The first gate insulating layer 170 may include silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, tantalum oxide, hafnium oxide, zirconium oxide, titanium oxide, or the like. These materials may be used alone or in combination with each other.

The first conductive layer is disposed on the first gate insulating layer 170. The first conductive layer may include a first gate electrode 121 disposed on the first active layer 126 of the first thin film transistor 120 (with the first gate insulating layer 170 interposed between the first active layer 126 and the first gate electrode 121), a second gate electrode 141 disposed on the second active layer 146 of the second thin film transistor 140, and a power wiring 161 disposed on the auxiliary layer 163. The first conductive layer may include one or more metals selected from molybdenum (Mo), aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu). The first conductive layer may be a single film or a multilayer film.

The second gate insulating layer 180 is disposed on the first conductive layer. The second gate insulating layer 180 may be an interlayer insulating film. The second gate insulating layer 180 may be made of an inorganic insulating material such as silicon oxide, silicon nitride, silicon oxynitride, hafnium oxide, aluminum oxide, titanium oxide, tantalum oxide, or zinc oxide.

The second conductive layer is disposed on the second gate insulating layer 180. The second conductive layer includes a capacitor electrode 128 disposed on the first gate electrode 121, with a second gate insulating layer interposed between the capacitor electrode 128 and the first gate electrode 121. The capacitor electrode 128 may form a storage capacitor with the first gate electrode 121.

The second conductive layer may include one or more metals selected from molybdenum (Mo), aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu), as with the first conductive layer.

An interlayer insulating layer 190 is disposed on the second conductive layer. The interlayer insulating layer 190 may be an interlayer insulating film. In addition, the interlayer insulating layer 190 may perform a surface planarization function. The interlayer insulating layer 190 may include an organic insulating material such as polyacrylate resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene ether resin, polyphenylene sulfide resin, or benzocyclobutene (BCB).

The third conductive layer is disposed on the interlayer insulating layer 190. The third conductive layer includes the first drain electrode 123 and the first source electrode 124 of the first thin film transistor 120, the second drain electrode 143 and the second source electrode 144 of the second thin film transistor 140, and the power electrode 162 disposed on the power wiring 161.

The first source electrode 124 and the first drain electrode 123 may be electrically connected to the first active layer 126 through a first contact hole 129 passing through the interlayer insulating layer 190 and the second gate insulating layer 180, respectively. The second source electrode 144 and the second drain electrode 143 may be electrically connected to the second active layer 146 through a second contact hole 149 penetrating the interlayer insulating layer 190 and the second gate insulating layer 180, respectively. The power electrode 162 may be electrically connected to the power wiring 161 through a third contact hole 169 penetrating the interlayer insulating layer 190 and the second gate insulating layer 180.

The third conductive layer may include one or more metals selected from aluminum (Al), molybdenum (Mo), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), titanium (Ti), tantalum (Ta), tungsten (W), and copper (Cu). The third conductive layer may be a single film or a multilayer film. For example, the third conductive layer may have a stack structure of Ti/Al/Ti, Mo/Al/Mo, Mo/AlGe/Mo, or Ti/Cu.

A via layer 200 is disposed on the third conductive layer. The via layer 200 may be made of an organic material such as polyacrylate resin, epoxy resin, phenol resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene ether resin, polyphenylene sulfide resin, or benzocyclobutene (BCB). The surface of the via layer 200 may be flat. The via layer 200 may serve as a base layer on which the first electrode 210, the second electrode 220, and the light emitting element 300 are disposed.

A plurality of dikes 410 and 420 may be disposed on the via layer 200. In each pixel PX, the banks 410 and 420 may be spaced facing each other, and the first and second electrodes 210 and 220 may be disposed on the banks 410 and 420 spaced apart from each other, for example, on the first and second banks 410 and 420, respectively. In fig. 20, three banks 410 and 420 (specifically, two first banks 410 and one second bank 420) are disposed in one pixel PX, and the first electrode 210 and the second electrode 220 are disposed to cover them, respectively.

Dikes 410 and 420 may be formed of substantially the same material in one process. In this case, the banks 410 and 420 may form a grid pattern. The dikes 410 and 420 may include Polyimide (PI).

The dikes 410 and 420 may protrude from the via layer 200 in a thickness direction. Each of the banks 410 and 420 may protrude upward from a plane in which the light emitting element 300 is disposed, and at least a portion of the protruding portion may have a slope.

The reflective layers 211 and 221 may be disposed on the slanted and protruding banks 410 and 420 to reflect light. The reflective layer may include a first reflective layer 211 and a second reflective layer 210.

The first reflective layer 211 may cover the first bank 410, and a portion of the first reflective layer 211 may be electrically connected to the first drain electrode 123 of the first thin film transistor 120 through the fourth contact hole 319_1 penetrating the via layer 200. The second reflective layer 221 may cover the second bank 420, and a portion of the second reflective layer 221 may be electrically connected to the power electrode 162 through a fifth contact hole 319_2 penetrating the via layer 200.

The reflective layers 211 and 221 may include a material having a high reflectivity in order to reflect light emitted from the light emitting element 300. For example, the reflective layers 211 and 221 may include, but are not limited to, materials such as silver (Ag) or copper (Cu).

The first electrode layer 212 and the second electrode layer 222 may be disposed on the first reflective layer 211 and the second reflective layer 221, respectively.

The first electrode layer 212 is directly disposed on the first reflective layer 211. The first electrode layer 212 may have substantially the same pattern as the first reflective layer 211. The second electrode layer 222 is disposed directly on the second reflective layer 221 and spaced apart from the first electrode layer 212. The second electrode layer 222 may have substantially the same pattern as the second reflective layer 221.

In an embodiment, the electrode layers 212 and 222 may cover the reflective layers 211 and 221 disposed thereunder, respectively. That is, the electrode layers 212 and 222 may be formed to be larger than the reflective layers 211 and 221 to cover side surfaces of end portions of the reflective layers 211 and 221. However, the present disclosure is not limited thereto.

The first electrode layer 212 and the second electrode layer 222 may transmit an electrical signal transmitted to the first reflective layer 211 and the second reflective layer 221 connected to the first thin film transistor 120 or the power electrode 162 to the contact electrode 261 or 262, respectively, which will be described later. The electrode layers 212 and 222 may include a transparent conductive material. For example, the electrode layers 212 and 222 may include, but are not limited to, a material such as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), or Indium Tin Zinc Oxide (ITZO). In some embodiments, the reflective layers 211 and 221 and the electrode layers 212 and 222 may form a structure in which one or more transparent conductive layers (such as ITO, IZO, or ITZO) and one or more metal layers (such as silver or copper) are stacked. For example, the reflective layers 211 and 221 and the electrode layers 212 and 222 may form an ITO/silver (Ag)/ITO stack structure.

The first reflective layer 211 and the first electrode layer 212 disposed on the first bank 410 constitute the first electrode 210. The first electrode 210 may protrude from both ends of the first bank 410. Thus, the protruding region of the first electrode 210 may contact the via layer 200. In addition, the second reflective layer 221 and the second electrode layer 222 disposed on the second bank 420 constitute the second electrode 220. The second electrode 220 may protrude from both ends of the second bank 420. Thus, the protruding regions of the second electrode 220 may contact the via layer 200.

The first electrode 210 and the second electrode 220 may cover the entire area of the first bank 410 and the entire area of the second bank 420, respectively. However, as described above, the first electrode 210 and the second electrode 220 are spaced apart to face each other. As will be described later, the first insulating layer 510 may be disposed between the electrodes, and the second insulating layer 520 and the light emitting element 300 may be disposed on the first insulating layer 510.

In addition, the first reflective layer 211 may receive a driving voltage from the first thin film transistor 120, and the second reflective layer 221 may receive a power supply voltage from the power wiring 161. Accordingly, the first electrode 210 and the second electrode 220 receive a driving voltage and a power voltage, respectively.

Specifically, the first electrode 210 may be electrically connected to the first thin film transistor 120, and the second electrode 220 may be electrically connected to the power wiring 161. Accordingly, the first and second contact electrodes 261 and 262 disposed on the first and second electrodes 210 and 220 may receive the driving voltage and the power supply voltage. The driving voltage and the power voltage may be transmitted to the light emitting element 300, and a predetermined current may flow through the light emitting element 300, thereby causing the light emitting element 300 to emit light.

The first insulating layer 510 is disposed on the first electrode 210 and the second electrode 220 to partially cover them. The first insulating layer 510 may cover most of the upper surfaces of the first and second electrodes 210 and 220, but may partially expose the first and second electrodes 210 and 220. In addition, the first insulating layer 510 may be disposed in a space between the first electrode 210 and the second electrode 220. In fig. 15, the first insulating layer 510 may be disposed along a space between the first electrode branch 210B and the second electrode branch 220B to have an island shape or a line shape in a plan view.

In fig. 16, a first insulating layer 510 is disposed in a space between one first electrode 210 (e.g., first electrode branch 210B) and one second electrode 220 (e.g., second electrode branch 220B). However, as described above, since the first electrodes 210 and the second electrodes 220 may also be provided in plural numbers, the first insulating layer 510 may also be provided between one first electrode 210 and the other second electrode 220, or between one second electrode 220 and the other first electrode 210.

The first insulating layer 510 may overlap some regions of the electrodes 210 and 220, for example, may partially overlap regions of the first and second electrodes 210 and 220 protruding in a direction facing each other. The first insulating layer 510 may also be disposed in a region where the electrodes 210 and 220 overlap the inclined side surfaces and the flat upper surfaces of the banks 410 and 420. Further, the first insulating layer 510 may be disposed on the sides of the first and second electrodes 210 and 220 opposite to the facing sides of the first and second electrodes 210 and 220 to partially cover them. That is, the first insulating layer 510 may be disposed to expose only central portions of the first and second electrodes 210 and 220.

A first insulating layer 510 may be disposed between the light emitting element 300 and the via layer 200. A lower surface of the first insulating layer 510 may contact the via layer 200, and the light emitting element 300 may be disposed on an upper surface of the first insulating layer 510. In addition, the first insulating layer 510 may contact the electrodes 210 and 220 on both sides to electrically insulate the electrodes 210 and 220 from each other.

For example, the first insulating layer 510 may cover respective ends of the first and second electrodes 210 and 220 protruding in a direction facing each other. A portion of the lower surface of the first insulating layer 510 may contact the via layer 200, and a portion and a side surface of the lower surface of the first insulating layer 510 may contact each electrode 210 or 220. Accordingly, the first insulating layer 510 may protect the region overlapping the electrodes 210 and 220 while electrically insulating the electrodes 210 and 220 from each other. In addition, it may prevent the first and second conductive type semiconductors 310 and 320 of the light emitting element 300 from directly contacting other members, thereby preventing damage to the light emitting element 300.

However, the present disclosure is not limited thereto. In some embodiments, the first insulating layer 510 may be disposed only on regions of the first and second electrodes 210 and 220 overlapping the inclined side surfaces of the banks 410 and 420. In this case, the lower surface of the first insulating layer 510 may terminate on the inclined side surfaces of the banks 410 and 420, and the electrodes 210 and 220 disposed on a portion of the inclined side surfaces of the banks 410 and 420 may be exposed to contact the contact electrode 260.

The first insulating layer 510 may be disposed to expose both ends of the light emitting element 300. Accordingly, the contact electrode 260 may contact the exposed upper surfaces of the electrodes 210 and 220 and both ends of the light emitting element 300, and may transmit the electrical signal transmitted to the first and second electrodes 210 and 220 to the light emitting element 300.

The light emitting element 300 may have one end electrically connected to the first electrode 210 and the other end electrically connected to the second electrode 220. Both ends of the light emitting element 300 may contact the first contact electrode 261 and the second contact electrode 262, respectively.

The light emitting element 300 may be a Light Emitting Diode (LED). The light emitting element 300 may be a nanostructure having substantially a nanometer size. The light emitting element 300 may be an inorganic LED made of an inorganic material. When the light emitting element 300 is an inorganic LED, if a light emitting material having an inorganic crystal structure is placed between two opposite electrodes and an electric field is formed in the light emitting material in a specific direction, the inorganic LED may be aligned between two electrodes in which a specific polarity is formed.

In some embodiments, the light emitting element 300 may have a structure in which a first conductive type semiconductor 310, an element active layer 330, a second conductive type semiconductor 320, and an electrode material layer 370 are stacked. In the light emitting element 300, the first conductive type semiconductor 310, the element active layer 330, the second conductive type semiconductor 320, and the electrode material layer 370 may be stacked in this order in a direction parallel to the via layer 200. In other words, the light emitting element 300 in which the above layers are stacked may be disposed in a horizontal direction parallel to the via layer 200. However, the present disclosure is not limited thereto, and the light emitting element 300 may also be aligned between the first electrode 210 and the second electrode 220 such that the stacking direction thereof is opposite to the above-described stacking direction. The structure of the light emitting element 300 will be described in detail later.

The second insulating layer 530 may be disposed on the light emitting element 300 to overlap at least a portion of the light emitting element 300. The second insulating layer 530 may protect the light emitting element 300 and fix the light emitting element 300 between the first electrode 210 and the second electrode 220.

Although the second insulating layer 530 is disposed on the upper surface of the light emitting element 300 in the cross section in fig. 16, the second insulating layer 530 may be disposed to cover the outer surface of the light emitting element 300. That is, similar to the first insulating layer 510, the second insulating layer 530 may extend in the second direction D2 along the space between the first and second electrode branches 210B and 220B to have an island shape or a line shape in a plan view.

In addition, a portion of the material of the second insulating layer 530 may be disposed in a region where the lower surface of the light emitting element 300 contacts the first insulating layer 510. This may be formed when the light emitting element 300 is aligned on the first insulating layer 510 and then the second insulating layer 530 is disposed on the light emitting element 300 during the manufacture of the display device 10. This may be because when the second insulating layer 530 is formed, a portion of the material of the second insulating layer 530 permeates into an air gap formed in the first insulating layer 510 in contact with the lower surface of the light emitting element 300.

The second insulating layer 530 is disposed to expose both side surfaces of the light emitting element 300. The second insulating layer 530 may be recessed inward from both side surfaces of the light emitting element 300. Accordingly, the side surfaces of the first insulating layer 510, the light emitting element 300, and the second insulating layer 530 may be stacked in a staircase-like pattern. In this case, the contact electrodes 261 and 262, which will be described later, may smoothly contact the side surfaces of both ends of the light emitting element 300. However, the present disclosure is not limited thereto, and the length of the second insulating layer 530 may also be equal to the length of the light emitting element 300 such that both sides thereof are aligned with each other.

The second insulating layer 530 may be disposed to cover the first insulating layer 510, and may then be patterned in some regions, for example, in regions where the light emitting element 300 is exposed to contact the contact electrode 260. The patterning of the second insulating layer 530 may be performed by conventional dry etching or wet etching. Here, in order to prevent the first insulating layer 510 from being patterned, the first insulating layer 510 and the second insulating layer 530 may include materials having different etch selectivities. In other words, when the second insulating layer 530 is patterned, the first insulating layer 510 may function as an etch stopper.

Therefore, even if the second insulating layer 530 is patterned to cover the outer surface of the light emitting element 300 and expose both ends of the light emitting element 300, the material of the first insulating layer 510 is not damaged. Specifically, the first insulating layer 510 and the light emitting element 300 may form smooth contact surfaces at both ends of the light emitting element 300 contacting the contact electrode 260.

The first and second contact electrodes 261 and 262 may be disposed on upper surfaces of the first and second electrodes 210 and 220, respectively. Specifically, the first and second contact electrodes 261 and 262 may contact the first and second electrode layers 212 and 222, respectively, in a region where the first insulating layer 510 is patterned to partially expose the first and second electrodes 210 and 220. Each of the first and second contact electrodes 261 and 262 may contact a side surface of an end portion of the light emitting element 300, for example, the first conductive type semiconductor 310, the second conductive type semiconductor 320, or the electrode material layer 370. Accordingly, the first and second contact electrodes 261 and 262 may transmit the electric signal transmitted to the first and second electrode layers 212 and 222 to the light emitting element 300.

The first contact electrode 261 may be disposed on the first electrode 210 to partially cover the first electrode 210, and a lower surface of the first contact electrode 261 may partially contact the light emitting element 300, the first insulating layer 510, and the second insulating layer 530. One end of the first contact electrode 261 in a direction in which the second contact electrode 262 is disposed on the second insulating layer 530. The second contact electrode 262 may be disposed on the second electrode 220 to partially cover the second electrode 220, and a lower surface of the second contact electrode 262 may partially contact the light emitting element 300, the first insulating layer 510, and the third insulating layer 540. One end of the second contact electrode 262 in the direction in which the first contact electrode 261 is disposed on the third insulating layer 540.

The first and second insulating layers 510 and 530 may be patterned in regions disposed to cover the first and second electrodes 210 and 220 on the upper surfaces of the first and second banks 410 and 420. Accordingly, the first and second electrode layers 212 and 222 of the first and second electrodes 210 and 220 may be exposed and may be electrically connected to the contact electrodes 261 and 262 in the exposed regions, respectively.

The first and second contact electrodes 261 and 262 may be spaced apart from each other on the second insulating layer 530 or the third insulating layer 540. That is, the first and second contact electrodes 261 and 262 may contact the light emitting element 300 and the second insulating layer 530 or the third insulating layer 540, but may be spaced apart from each other in the stacking direction on the second insulating layer 530, and thus electrically insulated from each other.

The contact electrodes 261 and 262 may include a conductive material such as, but not limited to, ITO, IZO, ITZO, or aluminum (Al).

In addition, the contact electrodes 261 and 262 may include the same material as the electrode layers 212 and 222. The contact electrodes 261 and 262 may be disposed on the electrode layers 212 and 222 in substantially the same pattern as the electrode layers 212 and 222 to contact the electrode layers 212 and 222.

A third insulating layer 540 may be disposed on the first contact electrode 261 to electrically insulate the first and second contact electrodes 261 and 262 from each other. The third insulating layer 540 may cover the first contact electrode 261 but may not overlap a portion of the light emitting element 300, so that the light emitting element 300 may contact the second contact electrode 262. On an upper surface of the second insulating layer 530, the third insulating layer 540 may partially contact the first contact electrode 261, the second contact electrode 262, and the second insulating layer 530. The third insulating layer 540 may cover one end of the first contact electrode 261 on the upper surface of the second insulating layer 530. Accordingly, the third insulating layer 540 may protect the first contact electrode 361 while electrically insulating the first contact electrode 261 from the second contact electrode 262.

One end of the third insulating layer 540 in a direction in which the second electrode 220 is disposed may be aligned with a side surface of the second insulating layer 530.

In some embodiments, the third insulating layer 540 may be omitted from the display device 10. Accordingly, the first and second contact electrodes 261 and 262 may be disposed on substantially the same plane and may be electrically insulated from each other by a passivation layer 550, which will be described later.

A passivation layer 550 may be formed on the third insulating layer 540 and the second contact electrode 262 to protect components disposed on the via layer 200 from the external environment. If the first and second contact electrodes 261 and 262 are exposed, the contact electrode material may be broken due to electrode damage. Thus, they may be covered by the passivation layer 550. That is, the passivation layer 550 may cover the first electrode 210, the second electrode 220, the light emitting element 300, and the like. In addition, as described above, if the third insulating layer 540 is omitted, the passivation layer 550 may be formed on the first and second contact electrodes 261 and 262. In this case, the passivation layer 550 may electrically insulate the first and second contact electrodes 261 and 262 from each other.

Each of the first insulating layer 510, the second insulating layer 530, the third insulating layer 540, and the passivation layer 550 described above may include an inorganic insulating material. For example, the first insulating layer 510, the second insulating layer 530, the third insulating layer 540, and the passivation layer 550 may include, for example, silicon oxide (SiO)_x) Silicon nitride (SiN)_x) Silicon oxynitride (SiO)_xN_y) Alumina (Al)₂O₃) Or aluminum nitride (AlN). A first insulating layer 510,The second insulating layer 530, the third insulating layer 540, and the passivation layer 550 may be made of the same material, but may also be made of different materials. In addition, various materials imparting insulating properties to the first insulating layer 510, the second insulating layer 530, the third insulating layer 540, and the passivation layer 550 may be applied.

The first insulating layer 510 and the second insulating layer 530 may have different etch selectivity as described above. For example, when the first insulating layer 510 includes silicon oxide (SiO)_x) When, the second insulating layer 530 may include silicon nitride (SiN)_x). For another example, when the first insulating layer 510 includes silicon nitride (SiN)_x) When, the second insulating layer 530 may include silicon oxide (SiO)_x). However, the present disclosure is not limited thereto.

The light emitting element 300 can be manufactured over a substrate by an epitaxial growth method. A seed layer for forming a semiconductor layer may be formed on the substrate, and a desired semiconductor material may be deposited and grown. The structure of the light emitting element 300 according to various embodiments will now be described in detail with reference to fig. 17.

Fig. 17 is a schematic diagram of a light-emitting element according to an embodiment. Referring to fig. 17, the light emitting element 300 may include a plurality of conductive type semiconductors 310 and 320, an element active layer 330, an electrode material layer 370, and an insulating material film 380. The electrical signal transmitted from the first electrode 210 and the second electrode 220 may be transmitted to the element active layer 330 through the conductive type semiconductors 310 and 320. Thus, light can be emitted.

Specifically, the light emitting element 300 may include a bar-shaped semiconductor core including a first conductive type semiconductor 310, a second conductive type semiconductor 320, an element active layer 330 disposed between the first conductive type semiconductor 310 and the second conductive type semiconductor 320, and an electrode material layer 370 disposed on the second conductive type semiconductor 320, and an insulating material film 380 surrounding an outer circumferential surface of the semiconductor core. The light emitting element 300 of fig. 17 has a structure in which a first conductive type semiconductor 310 of a semiconductor core, an element active layer 330, a second conductive type semiconductor 320, and an electrode material layer 370 are sequentially stacked in a longitudinal direction. However, the present disclosure is not limited thereto. The electrode material layer 370 may be omitted, and in some embodiments, the electrode material layer 370 may be disposed on at least any one of both side surfaces of the first and second conductive type semiconductors 310 and 320. The light emitting element 300 of fig. 4 will be described below as an example, and it is apparent that the following description of the light emitting element 300 can be identically applied even if the light emitting element 300 further includes another structure.

The first conductive type semiconductor 310 may be an n-type semiconductor layer. In an example, when the light emitting element 300 emits light In a blue wavelength band, the first conductive type semiconductor 310 may be of a chemical formula In_xAl_yGa_1-x-yN (0. ltoreq. x.ltoreq.1, 0. ltoreq. y.ltoreq.1, 0. ltoreq. x + y. ltoreq.1), for example, may be any one or more of N-type doped InAlGaN, GaN, AlGaN, InGaN, AlN and InN. The first conductive type semiconductor 310 may be doped with a first conductive dopant, and the first conductive dopant may be, for example, Si, Ge, or Sn. The length of the first conductive type semiconductor 310 may be in the range of 1.5 to 5 μm, but is not limited thereto.

The second conductive type semiconductor 320 may be a p-type semiconductor layer. In an example, when the light emitting element 300 emits light In a blue wavelength band, the second conductive type semiconductor 320 may be of a chemical formula In_xAl_yGa_1-x-yThe semiconductor material of N (0. ltoreq. x.ltoreq.1, 0. ltoreq. y.ltoreq.1, 0. ltoreq. x + y. ltoreq.1) may be, for example, any one or more of p-type doped InAlGaN, GaN, AlGaN, InGaN, AlN, and InN. The second conductive type semiconductor 320 may be doped with a second conductive dopant, and the second conductive dopant may be, for example, Mg, Zn, Ca, Se, or Ba. The length of the second conductive type semiconductor 320 may be in the range of 0.08 to 0.25 μm, but is not limited thereto.

The element active layer 330 may be disposed between the first conductive type semiconductor 310 and the second conductive type semiconductor 320, and may include a material having a single quantum well structure or a multiple quantum well structure. When the element active layer 330 includes a material having a multiple quantum well structure, it may have a structure in which a plurality of quantum layers and a plurality of well layers are alternately stacked. The element active layer 330 may emit light by a combination of electron-hole pairs according to an electrical signal received through the first and second conductive type semiconductors 310 and 320. For example, when the element active layer 330 emits light in a blue wavelength band, it may include a material such as AlGaN or AlInGaN. Specifically, when the element active layer 330 has a multiple quantum well structure in which quantum layers and well layers are alternately stacked, the quantum layers may include a material such as AlGaN or AlInGaN, and the well layers may include a material such as GaN or AlGaN. However, the present disclosure is not limited thereto, and the element active layer 330 may also have a structure in which a semiconductor material having a large band gap energy and a semiconductor material having a small band gap energy are alternately stacked, or may include different group 3 or group 5 semiconductor materials according to a wavelength band of emitted light. Therefore, the light emitted from the element active layer 330 is not limited to light in a blue wavelength band, but may also be light in a red wavelength band and a green wavelength band in some cases. The length of the element active layer 330 may be in the range of 0.05 to 0.25 μm, but is not limited thereto.

Light emitted from the element active layer 330 may be radiated not only to the outer surface of the light emitting element 300 in the longitudinal direction but also to both side surfaces. That is, the direction of light emitted from the element active layer 330 is not limited to one direction.

The electrode material layer 370 may be an ohmic contact electrode. However, the present disclosure is not limited thereto, and the electrode material layer 370 may also be a schottky contact electrode. The electrode material layer 370 may include a conductive metal. For example, the electrode material layer 370 may include at least any one of aluminum (Al), titanium (Ti), indium (In), gold (Au), and silver (Ag). The electrode material layer 370 may include the same material or different materials, but the present disclosure is not limited thereto.

The insulating material film 380 surrounds the outer peripheral surface of the semiconductor core. Specifically, the insulating material film 380 may be formed outside the first conductive type semiconductor 310, the second conductive type semiconductor 320, the element active layer 330, and the electrode material layer 370, and may protect them. For example, the insulating material film 380 may be formed to surround the sides of the above members, and may not be formed at both ends in the longitudinal direction of the light emitting element 300, for example, at both ends where the first conductivity-type semiconductor 310 and the electrode material layer 370 are provided. However, the present disclosure is not limited thereto.

In the drawing, an insulating material film 380 extends in the longitudinal direction to cover from the first conductivity-type semiconductor 310 to the electrode material layer 370. However, the present disclosure is not limited thereto, and the insulating material film 380 may cover only the first conductive type semiconductor 310, the element active layer 330, and the second conductive type semiconductor 320, or may cover only a portion of the outer surface of the electrode material layer 370 to expose a portion of the outer surface of the electrode material layer 370.

The thickness of the insulating material film 380 may be in the range of 0.5 to 1.5 μm, but is not limited thereto.

The insulating material film 380 may include an insulating film 381 and an element coupler 385 coupled to the insulating film 381. The insulating film 381 may have an insulating property and protect the first conductive type semiconductor 310, the second conductive type semiconductor 320, the element active layer 330, and the electrode material layer 370.

The insulating film 381 may include an insulating material such as silicon oxide (SiO)_x) Silicon nitride (SiN)_x) Silicon oxynitride (SiO)_xN_y) Aluminum nitride (AlN) or aluminum oxide (Al)₂O₃). Accordingly, an electrical short that may occur when the element active layer 330 directly contacts the first electrode 210 or the second electrode 220 may be prevented. Further, since the outer peripheral surface of the light emitting element 300 including the element active layer 330 is protected by the insulating film 381, a decrease in light emission efficiency can be prevented.

Further, the outer peripheral surface of the insulating film 381 may be surface-treated, and the element coupler 385 may be coupled to at least a part of the surface. The element coupler 385 may form a covalent bond with the second insulating layer 520 and fix the light emitting element 300 between the electrodes 210 and 220 during the manufacturing of the display device 10.

A method of manufacturing the above-described display device will now be described.

Fig. 18 and 19 are sectional views respectively showing operations in the display device manufacturing method according to the embodiment. For ease of description, components disposed below the via layer 200 are not shown in fig. 18.

Referring to fig. 18, a substrate including a via layer 200, a first bank 410 and a second bank 420 disposed on the via layer 200 and spaced apart from each other, and a first insulating material layer 510' disposed to cover them is prepared. The above-described members may be formed by patterning a metal, an inorganic material, or an organic material in a conventional mask process.

Referring to fig. 19, the light emitting element 300 is dropped and aligned on the first electrode 210 and the second electrode 220. The light emitting elements 300 are a kind of dipole, and the alignment of the light emitting elements 300 may be performed using the inkjet printing apparatus and the dipole alignment method described above. Therefore, redundant description will be omitted.

Next, the above-described components (e.g., the contact electrode 260, the third insulating layer 540, and the passivation layer 550) are formed by performing additional processes, thereby manufacturing the display device 10. Specifically, the first insulating material layer 510' may be partially removed so that the contact electrode 260 contacts the first and second electrodes 210 and 220. Accordingly, the first insulating layer 510 of fig. 16 may be formed.

As described above, in the method according to the embodiment, the light emitting element 300 may be aligned between the first electrode 210 and the second electrode 220 with a high degree of alignment. The improved alignment may reduce connection or contact failure between the light emitting element 300 and each electrode 210 or 220 or each contact electrode 260 and improve reliability of each pixel PX of the display device 10.

At the conclusion of the detailed description, those skilled in the art will appreciate that many variations and modifications may be made to the preferred embodiments without substantially departing from the principles of the present invention. Accordingly, the disclosed preferred embodiments of the invention are used in a generic and descriptive sense only and not for purposes of limitation.