Light-emitting element ink and method for manufacturing display device

Abstract

A light-emitting element ink and a method for manufacturing a display device are provided. The light-emitting element ink comprises a light-emitting element solvent; a light-emitting element dispersed in the light-emitting element solvent, the light-emitting element comprising a plurality of semiconductor layers and an insulating film surrounding the outer surface of the semiconductor layer; and a thickener dispersed in the light-emitting element solvent, wherein a compound of the thickener comprises a functional group capable of forming a hydrogen bond with a compound of the light-emitting element solvent or another compound of the thickener, and the compound of the thickener is represented by the following chemical formula 1: Chemical formula 1

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0048795, filed on Apr. 22, 2020, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to a light emitting element ink and a method for manufacturing a display device. For example, the present disclosure relates to a light emitting element ink whose viscosity can be adjusted according to conditions by including a thickener, and a method for manufacturing a display device using the light emitting element ink. Background Art

[0004] The importance of display devices has increased with the development of multimedia. Therefore, various types (or kinds) of display devices have been used, for example, taking organic light emitting displays (OLEDs) and liquid crystal displays (LCDs) as examples.

[0005] A display device for displaying an image includes a display panel, such as an organic light emitting display panel or a liquid crystal display panel. In the display panel, the organic light emitting display panel includes an organic light emitting element, such as a light emitting diode (LED). The light emitting diode (LED) may include an organic light emitting diode (OLED) using an organic material as a fluorescent material and an inorganic light emitting diode using an inorganic material as a fluorescent material. Summary of the invention

[0006] An aspect of an embodiment of the present disclosure provides a light emitting element ink in which a light emitting element does not precipitate during storage by including a thickener.

[0007] Another aspect of an embodiment of the present disclosure provides a method of manufacturing a display device using the light emitting element ink, wherein foreign matter is completely (or substantially completely) removed after a printing process to improve product reliability.

[0008] However, aspects of the embodiments of the present disclosure are not limited to the aspects set forth herein. The above and other aspects of the embodiments of the present disclosure will become more apparent to those skilled in the art to which the present disclosure belongs by referring to the detailed description of the embodiments of the present disclosure given below.

[0009] According to an exemplary embodiment of the present disclosure, a light-emitting element ink includes a light-emitting element solvent; light-emitting elements dispersed in the light-emitting element solvent, each light-emitting element including a plurality of semiconductor layers and an insulating film surrounding an outer surface of the semiconductor layer; and a thickener dispersed in the light-emitting element solvent, wherein a compound of the thickener includes a functional group capable of forming a hydrogen bond with a compound of the light-emitting element solvent or another compound of the thickener, and the compound of the thickener is represented by the following Chemical Formula 1:

[0010] Chemical formula 1

[0011]

[0012] Wherein, in Chemical Formula 1, each R 1 may independently be a substituted or unsubstituted alkylene group having 6 to 8 carbon atoms, a substituted or unsubstituted alkenylene group having 6 to 8 carbon atoms, or a substituted or unsubstituted alkynylene group having 6 to 8 carbon atoms, and each R 2 Independently, may be an alkyl group having 3 to 8 carbon atoms.

[0013] The compound of the thickener may be represented by any one selected from Chemical Formula 2 to Chemical Formula 6:

[0014] Chemical formula 2

[0015]

[0016] Chemical formula 3

[0017]

[0018] Chemical formula 4

[0019]

[0020] Chemical formula 5

[0021]

[0022] Chemical formula 6

[0023]

[0024] In chemical formula 4, R 3 Yes*-(CH 2 CH 2 O) x CH 3 , x is an integer from 7 to 112, and *- is a bond to an oxygen atom (O).

[0025] In a state in which shear stress is not applied to the light emitting element ink, the compound of the thickener may form intermolecular hydrogen bonds together with the compound of the light emitting element solvent and the other compound of the thickener to form a network structure.

[0026] The light emitting element ink may have a viscosity of 30 cP to 300 cP measured at 25° C. in a state in which shear stress is not applied to the light emitting element ink.

[0027] In a state where shear stress is applied to the light-emitting element ink, the compound of the thickener may not form an intermolecular hydrogen bond with the compound of the light-emitting element solvent and the other compound of the thickener, and the light-emitting element ink may have a viscosity of 5 cP to 15 cP measured at 25°C.

[0028] The light emitting element may be contained in the light emitting element ink in an amount of 0.01 to 1 parts by weight relative to 100 parts by weight of the light emitting element ink, and the thickener may be contained in the light emitting element ink in an amount of 100 to 500 parts by weight relative to 100 parts by weight of the light emitting element.

[0029] The light emitting element ink may further include a dispersant dispersed in the light emitting element solvent, wherein the dispersant may be included in the light emitting element ink in an amount of 10 to 50 parts by weight relative to 100 parts by weight of the light emitting element.

[0030] The semiconductor layer of the light emitting element may include a first semiconductor layer, a second semiconductor layer, and a light emitting layer between the first semiconductor layer and the second semiconductor layer, and the insulating film of the light emitting element may surround at least an outer surface of the light emitting layer.

[0031] According to an exemplary embodiment of the present disclosure, a method for manufacturing a display device includes: preparing a light-emitting element ink comprising a light-emitting element solvent, a plurality of light-emitting elements and a thickener, and preparing a target substrate, the target substrate comprising a first electrode and a second electrode; spraying the light-emitting element ink onto the target substrate; forming an electric field on the target substrate to place the light-emitting element on the first electrode and the second electrode; and heat-treating the light-emitting element ink in a low-pressure environment to remove the light-emitting element solvent and the thickener.

[0032] The compound of the thickener of the light emitting element ink may include a functional group capable of forming a hydrogen bond with a compound of the light emitting element solvent or another compound of the thickener, and include a compound represented by Chemical Formula 1 above.

[0033] The compound of the thickener may be represented by any one selected from Chemical Formula 2 to Chemical Formula 6 above.

[0034] The light emitting element may be contained in the light emitting element ink in an amount of 0.01 to 1 parts by weight relative to 100 parts by weight of the light emitting element ink, and the thickener may be contained in the light emitting element ink in an amount of 100 to 500 parts by weight relative to 100 parts by weight of the light emitting element.

[0035] In the preparation of the light emitting element ink, the compound of the thickener may form an intermolecular hydrogen bond together with the compound of the light emitting element solvent and the other compound of the thickener to form a network structure.

[0036] In the preparing of the light emitting element ink, the light emitting element ink may have a viscosity of 30 cP to 300 cP measured at 25°C.

[0037] In the ejection of the light emitting element ink, the light emitting elements in the light emitting element ink may be redispersed.

[0038] The ejection of the light emitting element ink may be performed through a printing process using an inkjet printing apparatus, a shear stress may be applied to the light emitting element ink, and the light emitting element ink may be ejected onto the target substrate through a nozzle.

[0039] In the ejecting of the light emitting element ink, the light emitting element ink may have a viscosity of 5 cP to 15 cP measured at 25°C.

[0040] Can be in 10 -4 The removing of the light emitting element solvent and the thickener is performed at a pressure of 0.1 torr to 1 torr and at a temperature of 25°C to 150°C.

[0041] In the placement of the light emitting element, a first end of the light emitting element may be on the first electrode, and a second end of the light emitting element may be on the second electrode.

[0042] Each of the light emitting elements may include a first semiconductor layer, a second semiconductor layer, an active layer between the first semiconductor layer and the second semiconductor layer, and an insulating film surrounding at least an outer surface of the active layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and other aspects and features of the embodiments of the present disclosure will become more apparent by describing in more detail exemplary embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0044] Figure 1is a schematic plan view of a display device according to the embodiment;

[0045] Figure 2 is a plan view illustrating one pixel of a display device according to the embodiment;

[0046] Figure 3 is along Figure 2 Cross-sectional views taken along line Q1-Q1', line Q2-Q2' and line Q3-Q3';

[0047] Figure 4 is a schematic partial cross-sectional view of a light emitting element according to the embodiment;

[0048] Figure 5 and Figure 6 is a schematic partial cross-sectional view of a light emitting element according to other embodiments;

[0049] Figure 7 is a schematic diagram of a light emitting element ink according to the embodiment;

[0050] Figure 8 It is shown in Figure 7 A schematic diagram of a bond between a thickener and a light-emitting element solvent in a storage state of a portion A of a light-emitting element ink;

[0051] Fig. 9 It is shown in Figure 7 A schematic diagram of a bond between a thickener and a light-emitting element solvent in a printed state of a portion A of a light-emitting element ink;

[0052] Fig.10 is a flowchart illustrating a method of manufacturing a display device according to the embodiment;

[0053] Figures 11 to 13 is a cross-sectional view illustrating effective actions in a process of manufacturing a display device according to the embodiment;

[0054] Fig.14 is a diagram illustrating a change in viscosity according to application of shear stress to the light emitting element ink;

[0055] Figures 15 to 17 is a cross-sectional view illustrating other effective actions in a process of manufacturing a display device according to the embodiment; and

[0056] Fig.18 is a cross-sectional view illustrating effective actions in a process of manufacturing a display device according to another embodiment. DETAILED DESCRIPTION

[0057] The subject matter of the present disclosure will now be described more fully below with reference to the accompanying drawings, in which certain embodiments of the present disclosure are shown. However, the subject matter of the present disclosure can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0058] 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. The same reference numerals refer to the same components throughout the specification.

[0059] It should be understood that although the terms "first", "second", etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the spirit and scope of the present disclosure, the first element discussed below can be referred to as the second element. Similarly, the second element can also be referred to as the first element.

[0060] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0061] Figure 1 is a schematic plan view of a display device according to the embodiment.

[0062] refer to Figure 1 The display device 10 displays a moving image or a still image. The display device 10 may refer to any suitable electronic device that provides a display screen. For example, the display device 10 may be used in a television, a notebook, a monitor, a billboard, an Internet of Things device, a mobile phone, a smart phone, a tablet personal computer (PC), an electronic watch, a smart watch, a watch phone, a head-mounted display, a mobile communication terminal, an electronic notebook, an electronic book, a portable multimedia player (PMP), a navigator (e.g., a navigation system), a game console, a digital camera, a video camera, etc.

[0063] The display device 10 includes a display panel for providing a display screen. Examples of the display panel may include an inorganic light emitting diode display panel, an organic light emitting display panel, a quantum dot light emitting display panel, a plasma display panel, and a field emission display panel. Hereinafter, a case where an inorganic light emitting diode display panel is used as a display panel will be exemplified, but the present disclosure is not limited thereto. Any suitable display panel may be used as the display panel, as long as substantially the same technical concept of the present disclosure is applicable.

[0064] The shape of the display device 10 may be variously modified. For example, the display device 10 may have a shape such as a rectangle with longer horizontal sides (e.g., longer than vertical sides), a rectangle with longer vertical sides (e.g., longer than horizontal sides), a square, a rectangle with rounded corners (vertices), other polygons, or a circle. The shape of the display area DPA of the display device 10 may also be similar to the overall shape of the display device 10. Figure 1 The display device 10 and the display area DPA are illustrated each having a rectangular shape having a longer horizontal side.

[0065] The display device 10 may include a display area DPA and a non-display area NDA. The display area DPA is an area in which an image is displayed, and the non-display area NDA is an area in which an image is not displayed (or an area not designed to display an image). The display area DPA may be referred to as an active area, and the non-display area NDA may be referred to as a non-active area. The display area DPA may generally occupy the center of the display device 10.

[0066] The display area DPA may include a plurality of pixels PX. The plurality of pixels PX may be arranged in a matrix direction. Each of the pixels PX may have a rectangular shape or a square shape in a plan view, but its shape is not limited thereto. Each of the pixels PX may have a rhombus shape in which each side is inclined relative to one direction. The individual pixels PX may be alternately arranged in a strip or pentile type (e.g., a strip pattern or a pentile pattern). Each of the pixels PX includes at least one light emitting element 30 that emits light having a set or specific wavelength band to display a set or specific color.

[0067] The non-display area NDA may be positioned around the display area DPA. The non-display area NDA may completely or partially surround the display area DPA. The display area DPA may have a rectangular shape, and the non-display area NDA may be adjacent to four sides of the display area DPA. The non-display area NDA may constitute a baffle of the display device 10. Wiring or circuit drivers included in the display device 10 may be in the non-display area NDA, and / or external devices may be installed in the non-display area NDA.

[0068] Figure 2 is a plan view illustrating one pixel of the display device according to the embodiment.

[0069] refer to Figure 2, each of the pixels PX may include a plurality of sub-pixels PXn (n is an integer from 1 to 3). For example, one pixel PX may include a first sub-pixel PX1, a second sub-pixel PX2, and a third sub-pixel PX3. The first sub-pixel PX1 may emit light of a first color, the second sub-pixel PX2 may emit light of a second color, and the third sub-pixel PX3 may emit light of a third color. For example, the first color may be blue, the second color may be green, and the third color may be red. However, the present disclosure is not limited thereto, and each of the sub-pixels PXn may emit light of the same (e.g., substantially the same) color. Although in Figure 2 2 shows that the pixel PX includes three sub-pixels PXn, and two pixels PX include six sub-pixels PXn, but the present disclosure is not limited thereto, and the pixel PX may include a greater number or a smaller number of sub-pixels PXn.

[0070] Each of the sub-pixels PXn of the display device 10 may include a light emitting area EMA and a non-light emitting area. The light emitting area EMA is defined as an area in which the light emitting element 30 is positioned to emit light having a set or specific wavelength band, and the non-light emitting area is defined as an area in which no light emitting element 30 is positioned and does not emit light (or is not designed to emit light). The light emitting area EMA may include an area in which the light emitting element 30 is positioned, and an area adjacent to the light emitting element 30 to release light emitted from the light emitting element 30.

[0071] However, the present disclosure is not limited thereto, and the light emitting area EMA may also include an area in which light emitted from the light emitting element 30 is reflected or refracted by another member and then emitted. A plurality of light emitting elements 30 may be arranged in each of the sub-pixels PXn, and the light emitting area may be formed by an area in which the plurality of light emitting elements 30 are arranged and an area adjacent to the area.

[0072] Each of the sub-pixels PXn may include a cutting area CBA in a non-luminous area. The cutting area CBA may be at one side of the luminous area EMA in the second direction DR2. The cutting area CBA may be between the luminous areas EMA of adjacent sub-pixels PXn in the second direction DR2. A plurality of luminous areas EMA and a plurality of cutting areas CBA may be arranged in the display area DPA of the display device 10. For example, a plurality of luminous areas EMA and a plurality of cutting areas CBA may be repeatedly arranged in the first direction DR1, respectively, and may be alternately arranged in the second direction DR2. The distance between the cutting areas CBA spaced apart from each other in the first direction DR1 may be less than the distance between the luminous areas EMA spaced apart from each other in the first direction DR1. The second block (bank) BNL2 is between the cutting area CBA and the luminous area EMA, and the distance between the cutting area CBA and the luminous area EMA may be changed or varied depending on the width of the second block BNL2. Since the light emitting element 30 is not in the cutting area CBA, it does not emit light, but a portion of the electrode (21 and 22) in each of the sub-pixels PXn may be positioned. The electrodes ( 21 and 22 ) positioned for each of the sub-pixels PXn may be separated from each other in the cutting area CBA.

[0073] Figure 3 is along Figure 2 Cross-sectional views taken along line Q1-Q1', line Q2-Q2' and line Q3-Q3'. Figure 3 Examples of cross Figure 2 FIG. 1 is a cross section of two ends of the light emitting element 30 in the first sub-pixel PX1.

[0074] refer to Figure 3 as well as Figure 2 The display device 10 may include a first substrate 11, and a semiconductor layer, a plurality of conductive layers, and a plurality of insulating layers on the first substrate 11. The semiconductor layer, the conductive layer, and the insulating layer may constitute (or form) a circuit layer and a light emitting element layer of the display device 10, respectively.

[0075] In some embodiments, the first substrate 11 may be an insulating substrate. The first substrate 11 may be made of an insulating material such as glass, quartz and / or a polymer resin. The first substrate 11 may be a rigid substrate, or may be a flexible substrate that can be bent, folded, rolled, etc.

[0076] The light blocking layer BML may be on the first substrate 11. The light blocking layer BML is positioned to overlap with the active layer ACT1 of the first transistor T1 of the display device 10. The light blocking layer BML may include a material that blocks light, thereby preventing or reducing light from entering the active layer ACT1 of the first transistor T1. For example, the light blocking layer BML may be formed of an opaque (or substantially opaque) metal material that blocks (or reduces) light transmission. However, the present disclosure is not limited thereto, and in some cases, the light blocking layer BML may be omitted.

[0077] The buffer layer 12 may be completely on the first substrate 11 and the light blocking layer BML. The buffer layer 12 may be formed on the first substrate 11 to protect the first transistor T1 of the pixel PX from moisture penetrating through the first substrate 11 (which is susceptible to moisture penetration), and may perform a surface planarization function. The buffer layer 12 may be formed as a plurality of inorganic layers alternately stacked. For example, the buffer layer 12 may be formed to have a multilayer structure in which inorganic layers including at least one selected from silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiOxNy) are alternately stacked.

[0078] The semiconductor layer is on the buffer layer 12. The semiconductor layer may include an active layer ACT1 of the first transistor T1. The semiconductor layer and the buffer layer 12 may partially overlap with a gate electrode G1 of a first gate conductive layer, which will be further described herein below, and the like.

[0079] In the drawings, only the first transistor T1 is illustrated among the transistors included in the sub-pixel PXn of the display device 10, but the present disclosure is not limited thereto. For example, the display device 10 may include a larger number of transistors. In some embodiments, for each sub-pixel PXn, the display device 10 may include two or three transistors, including one or more transistors in addition to the first transistor T1.

[0080] The semiconductor layer may include polycrystalline silicon, monocrystalline silicon and / or an oxide semiconductor. When the semiconductor layer includes an oxide semiconductor, each active layer ACT1 may include a plurality of conduction regions (e.g., conductive regions) (ACT_a and ACT_b) and a channel region ACT_c therebetween. The oxide semiconductor may be an oxide semiconductor containing indium (In). For example, the oxide semiconductor may include indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium oxide (IGO), indium zinc tin oxide (IZTO), indium gallium tin oxide (IGTO), indium gallium zinc oxide (IGZO) and / or indium gallium zinc tin oxide (IGZTO).

[0081] In another embodiment, the semiconductor layer may include polycrystalline silicon. Polycrystalline silicon may be formed by crystallizing amorphous silicon, and in this case, the conduction regions (eg, conductive regions) of the active layer ACT1 may be doped regions doped with impurities, respectively.

[0082] The first gate insulating layer 13 is on the semiconductor layer and the buffer layer 12. The first gate insulating layer 13 may be on the buffer layer 12 in addition to the semiconductor layer. The first gate insulating layer 13 may function as a gate insulating film of each transistor. The first gate insulating layer 13 may be formed of an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx) and / or silicon oxynitride (SiOxNy), or may be formed as a stacked structure of inorganic layers.

[0083] The first gate conductive layer is on the first gate insulating layer 13. The first gate conductive layer may include a gate electrode G1 of the first transistor T1 and a first capacitor electrode CSE1 of the storage capacitor. The gate electrode G1 may overlap with the channel region ACT_c of the active layer ACT1 in the thickness direction. The first capacitor electrode CSE1 may overlap with the second capacitor electrode CSE2, which will be further described herein below, in the thickness direction. In an embodiment, the first capacitor electrode CSE1 may be integrated with the gate electrode G1. The first capacitor electrode CSE1 may overlap with the second capacitor electrode CSE2 in the thickness direction, and a storage capacitor may be formed therebetween.

[0084] The first gate conductive layer may be formed as a single layer or a plurality of layers including any one selected from molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and alloys thereof. However, the present disclosure is not limited thereto.

[0085] The first interlayer insulating layer 15 is on the first gate conductive layer. The first interlayer insulating layer 15 may function as an insulating film between the first gate conductive layer and other layers thereon. The first interlayer insulating layer 15 may cover the first gate conductive layer to perform the function of protecting the first gate conductive layer. The first interlayer insulating layer 15 may be formed of an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx) and / or silicon oxynitride (SiOxNy), or may be formed as a stacked structure of inorganic layers.

[0086] The first data conducting layer is on the first interlayer insulating layer 15. The first data conducting layer may include a first source electrode S1 and a first drain electrode D1 of the first transistor T1, a data line DTL, and a second capacitor electrode CSE2.

[0087] The first source electrode S1 and the first drain electrode D1 of the first transistor T1 may respectively contact (e.g., physically contact) the doping region ACT_a and the doping region ACT_b of the active layer ACT1 through contact holes penetrating the first interlayer insulating layer 15 and the first gate insulating layer 13. In addition, the first source electrode S1 of the first transistor T1 may be electrically coupled to the light blocking layer BML through another contact hole.

[0088] The data line DTL may apply a data signal to another transistor included in the display device 10. The data line DTL may be coupled to a source electrode / drain electrode of another transistor to transfer a signal applied from the data line DTL.

[0089] The second capacitor electrode CSE2 may overlap the first capacitor electrode CSE1 in the thickness direction. In an embodiment, the second capacitor electrode CSE2 may be integrally coupled to the first source electrode S1.

[0090] The first data conducting layer may be formed as a single layer or a plurality of layers including any one selected from molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and alloys thereof. However, the present disclosure is not limited thereto.

[0091] The second interlayer insulating layer 17 is on the first data conducting layer. The second interlayer insulating layer 17 may function as an insulating film between the first data conducting layer and other layers thereon. The second interlayer insulating layer 17 may cover the first data conducting layer to perform a function of protecting the first data conducting layer. The second interlayer insulating layer 17 may be formed of an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), and / or silicon oxynitride (SiOxNy), or may be formed as a stacked structure of inorganic layers.

[0092] The second data conducting layer is on the second interlayer insulating layer 17. The second data conducting layer may include a first voltage line VL1, a second voltage line VL2, and a first conductive pattern CDP. A high potential voltage (or a first power supply voltage) supplied to the first transistor T1 may be applied to the first voltage line VL1, and a low potential voltage (or a second power supply voltage) supplied to the second electrode 22 may be applied to the second voltage line VL2. During the process of manufacturing the display device 10, an alignment signal for aligning the light emitting element 30 may be applied to the second voltage line VL2.

[0093] The first conductive pattern CDP may be coupled to the second capacitor electrode CSE2 through a contact hole formed in the second interlayer insulating layer 17. The second capacitor electrode CSE2 may be integrated with the first source electrode S1 of the first transistor T1, and the first conductive pattern CDP may be electrically coupled to the first source electrode S1. The first conductive pattern CDP may also be in contact (e.g., physically in contact) with the first electrode 21, which will be further described herein below, and the first transistor T1 may transmit the applied first power supply voltage from the first voltage line VL1 to the first electrode 21 through the first conductive pattern CDP. Although the second data conductive layer is shown in the drawings to include one second voltage line VL2 and one first voltage line VL1, the present disclosure is not limited thereto. The second data conductive layer may include a larger number of first voltage lines VL1 and a larger number of second voltage lines VL2.

[0094] The second data conducting layer may be formed as a single layer or a plurality of layers including any one selected from molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and alloys thereof. However, the present disclosure is not limited thereto.

[0095] The first planarization layer 19 is on the second data conducting layer. The first planarization layer 19 may include an organic insulating material, for example, an organic material such as polyimide (PI), to perform a surface planarization function.

[0096] A plurality of first blocks BNL1, a plurality of electrodes (21, 22), a light emitting element 30, a plurality of contact electrodes (CNE1 and CNE2), and a second block BNL2 are on the first planarization layer 19. In addition, a plurality of insulating layers (PAS1, PAS2, PAS3, and PAS4) may be on the first planarization layer 19.

[0097] A plurality of first blocks BNL1 may be directly on the first planarization layer 19. The plurality of first blocks BNL1 have a shape extending in the second direction DR2 within each subpixel PXn, but do not extend to another adjacent subpixel PXn in the second direction DR2, and may be in the light emitting area EMA. The plurality of first blocks BNL1 may be spaced apart from each other in the first direction DR1, and the light emitting element 30 may be between the plurality of first blocks BNL1. A plurality of first blocks BNL1 may be provided for each subpixel PXn to form a linear pattern in the display area DPA of the display device 10. In the drawings, two first blocks BNL1 are shown, but the present disclosure is not limited thereto. Depending on the number of electrodes (21 and 22), a greater number of first blocks BNL1 may be arranged.

[0098] The first block BNL1 may have a structure in which at least a portion of the first block BNL1 protrudes from the upper surface of the first planarization layer 19. The protruding portion of the first block BNL1 may have an inclined side surface (e.g., inclined relative to the upper surface of the first planarization layer 19), and light emitted from the light emitting element 30 may be reflected by the electrodes (21 and 22) on the first block BNL1 and emitted in an upward direction of the first planarization layer 19. The first block BNL1 may provide a region in which the light emitting element 30 is positioned, and at the same time may function as a reflective barrier that reflects light emitted from the light emitting element 30 in an upward direction. The side surface of the first block BNL1 may be inclined in a linear shape, but is not limited thereto, and the first block BNL1 may have a curved semicircular or semi-elliptical shape. The first block BNL1 may include an organic insulating material such as polyimide (PI), but the material thereof is not limited thereto.

[0099] The plurality of electrodes (21 and 22) are on the first block BNL1 and the first planarization layer 19. The plurality of electrodes (21 and 22) may include first electrodes 21 and second electrodes 22. The first electrodes 21 and the second electrodes 22 may extend in the second direction DR2 and may be spaced apart from each other in the first direction DR1.

[0100] Each of the first electrode 21 and the second electrode 22 may extend in the second direction DR2 within the sub-pixel PXn, and may be separated from the other electrodes (21 and 22) in the cutting area CBA. For example, the cutting area CBA may be between the light emitting areas EMA of the sub-pixels PXn adjacent in the second direction DR2, and the first electrode 21 and the second electrode 22 may be separated from the other first electrodes 21 and the second electrodes 22 in the sub-pixels PXn adjacent in the second direction DR2 in the cutting area CBA. However, the present disclosure is not limited thereto, and for each pixel PXn, some of the electrodes (21 and 22) may extend beyond the sub-pixels adjacent in the second direction DR2 without being separated from each other, or only one of the first electrode 21 and the second electrode 22 may be separated.

[0101] The first electrode 21 may be electrically coupled to the first transistor T1 through the first contact hole CT1, and the second electrode 22 may be electrically coupled to the second voltage line VL2 through the second contact hole CT2. For example, in a portion of the second block BNL2 extending in the first direction DR1, the first electrode 21 may contact (e.g., physically contact) the first conductive pattern CDP through the first contact hole CT1 penetrating the first planarization layer 19. In a portion of the second block BNL2 extending in the first direction DR1, the second electrode 22 may also contact (e.g., physically contact) the second voltage line VL2 through the second contact hole CT2 penetrating the first planarization layer 19. However, the present disclosure is not limited thereto. In another embodiment, the first contact hole CT1 and the second contact hole CT2 may be in the light emitting area EMA surrounded by the second block BNL2 so as not to overlap with the second block BNL2.

[0102] Although it is illustrated in the drawings that one first electrode 21 and one second electrode 22 are provided for each sub-pixel PXn, the present disclosure is not limited thereto, and the number of the first electrode 21 and the second electrode 22 provided for each sub-pixel PXn may be larger. The first electrode 21 and the second electrode 22 in each sub-pixel PXn may not necessarily have a shape extending in one direction, and the first electrode 21 and the second electrode 22 may have various suitable structures. For example, the first electrode 21 and the second electrode 22 may have a partially bent or curved shape, and one electrode may be arranged to surround the other electrode.

[0103] Each of the first electrode 21 and the second electrode 22 may be directly on the first block BNL1. Each of the first electrode 21 and the second electrode 22 may be formed to have a greater width than the first block BNL1. For example, each of the first electrode 21 and the second electrode 22 may cover the outer surface of the first block BNL1. Each of the first electrode 21 and the second electrode 22 may be on the side surface of the first block BNL1, and the interval between the first electrode 21 and the second electrode 22 may be narrower than the interval between the first blocks BNL1. At least a portion of the first electrode 21 and at least a portion of the second electrode 22 are directly on the first planarization layer 19, so that the first electrode 21 and the second electrode 22 may be on the same plane. However, the present disclosure is not limited thereto. In some cases, each of the electrodes (21 and 22) may have a width less than the width of the first block BNL1. However, each of the electrodes (21 and 22) may cover at least one side surface of the first block BNL1 to reflect light emitted from the light emitting element 30.

[0104] Each of the electrodes (21 and 22) may include a conductive material having high reflectivity. For example, each of the electrodes (21 and 22) may include a metal such as silver (Ag), copper (Cu), and / or aluminum (Al) as a conductive material having high reflectivity, and / or may include an alloy containing aluminum (Al), nickel (Ni), and / or lanthanum (La). Each of the electrodes (21 and 22) may reflect light emitted by the light emitting element 30 and advancing to the side surface of the first block BNL1 in the upward direction of each sub-pixel PXn.

[0105] However, the present disclosure is not limited thereto, and each of the electrodes (21 and 22) may further include a transparent conductive material. For example, each of the electrodes (21 and 22) may include a material such as indium tin oxide (ITO), indium zinc oxide (IZO) and / or indium tin zinc oxide (ITZO). In some embodiments, each of the electrodes (21 and 22) may have a structure in which one or more transparent conductive material layers and one or more metal layers with high reflectivity are stacked, or may be formed as a layer containing them. For example, each of the electrodes (21 and 22) may have a stacked structure of ITO / Ag / ITO, ITO / Ag / IZO, or ITO / Ag / ITZO / IZO.

[0106] The plurality of electrodes (21 and 22) may be electrically coupled to the light emitting element 30, and a set or predetermined voltage may be applied to the electrodes (21 and 22) so that the light emitting element 30 emits light. The plurality of electrodes (21 and 22) may be electrically coupled to the light emitting element 30 through the contact electrodes (CNE1 and CNE2), and an electrical signal applied to the electrodes (21 and 22) may be transmitted to the light emitting element 30 through the contact electrodes (CNE1 and CNE2).

[0107] One of the first electrode 21 and the second electrode 22 may be electrically coupled to the anode electrode of the light emitting element 30, and the other thereof may be electrically coupled to the cathode electrode of the light emitting element 30. However, the present disclosure is not limited thereto, and vice versa.

[0108] Each of the electrodes (21 and 22) can be used to form an electric field in the sub-pixel PXn to align the light-emitting element 30. By forming the electric field on the first electrode 21 and the second electrode 22, the light-emitting element 30 can be between the first electrode 21 and the second electrode 22. The light-emitting element 30 of the display device 10 can be sprayed on the electrodes (21 and 22) by an inkjet printing process. When the ink including the light-emitting element 30 is sprayed on the electrodes (21 and 22), an alignment signal is applied to the electrodes (21 and 22) to form an electric field. The light-emitting element 30 dispersed in the ink can be aligned on the electrodes (21 and 22) by receiving the dielectrophoretic force through the electric field formed on the electrodes (21 and 22).

[0109] The first insulating layer PAS1 is on the first planarization layer 19. The first insulating layer PAS1 may cover the first block BNL1, the first electrode 21, and the second electrode 22. The first insulating layer PAS1 may protect the first electrode 21 and the second electrode 22 and insulate them from each other (e.g., electrically insulate). In addition, the first insulating layer PAS1 may prevent or reduce damage to the light emitting element 30 thereon due to direct contact with other components.

[0110] In an embodiment, the first insulating layer PAS1 may include openings OP partially exposing the first electrode 21 and the second electrode 22. Each opening OP may partially expose a portion of the electrodes (21 and 22) on the upper surface of the first block BNL1. A portion of the contact electrodes (CNE1 and CNE2) may contact (e.g., physically contact) each of the electrodes (21 and 22) exposed through the openings OP.

[0111] A step may be formed in the first insulating layer PAS1 so that a portion of the upper surface of the first insulating layer PAS1 is recessed between the first electrode 21 and the second electrode 22. For example, when the first insulating layer PAS1 covers the first electrode 21 and the second electrode 22, the upper surface of the first insulating layer PAS1 may be stepped according to the shape of each of the electrodes (21 and 22) therebelow. However, the present disclosure is not limited thereto.

[0112] The second block BNL2 may be on the first insulating layer PAS1. The second block BNL2 may be in a grid pattern on the entire (or substantially the entire) surface of the display area DPA, and include portions extending in the first direction DR1 and the second direction DR2 on a plane. The second block BNL2 may extend across boundaries of each sub-pixel PXn to distinguish adjacent sub-pixels PXn.

[0113] In addition, the second block BNL2 may surround the light emitting area EMA and the cutting area CBA provided for each sub-pixel PXn to distinguish the light emitting area EMA from the cutting area CBA. The first electrode 21 and the second electrode 22 may extend in the second direction DR2 across the portion of the second block BNL2 extending in the first direction DR1. In the portion of the second block BNL2 extending in the second direction DR2, the portion between the light emitting areas EMA may have a greater width than the portion between the cutting areas CBA. Therefore, the distance between the cutting areas CBA may be smaller than the distance between the light emitting areas EMA.

[0114] The second block BNL2 may be formed to have a greater height than the first block BNL1. The second block BNL2 may prevent or reduce ink from overflowing to adjacent sub-pixels PXn during inkjet printing in the process of manufacturing the display device 10, so that inks in which different light emitting elements 30 are dispersed for each sub-pixel PXn may be separated from each other without mixing with each other. Like the first block BNL1, the second block BNL2 may include polyimide (PI), but the material thereof is not limited thereto.

[0115] The light emitting element 30 may be on the first insulating layer PAS1. A plurality of light emitting elements 30 may be arranged to be spaced apart from each other along a second direction DR2 in which the electrodes (21 and 22) extend, and may be aligned substantially parallel to each other (e.g., substantially parallel to each other). The light emitting element 30 may have a shape extending in one direction, and the direction in which each of the electrodes (21 and 22) extends may be substantially perpendicular to the direction in which the light emitting element 30 extends. However, the present disclosure is not limited thereto, and the light emitting element 30 may extend obliquely at a set or predetermined angle without being perpendicular to the direction in which each of the electrodes (21 and 22) extends.

[0116] The light emitting element 30 in each sub-pixel PXn may include a light emitting layer ( Figure 4 36) to emit light with different wavelengths to the outside. Therefore, the light of the first color, the light of the second color, and the light of the third color can be emitted by the first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3, respectively. However, the present disclosure is not limited thereto, and each of the sub-pixels PXn includes the same type (or kind) of light emitting elements 30 to emit light of substantially the same color.

[0117] The light emitting element 30 may have both ends on each of the electrodes (21 and 22) between the first block BNL1. The elongated length of the light emitting element 30 is longer than the distance between the first electrode 21 and the second electrode 22, and both ends of the light emitting element 30 may be on the first electrode 21 and the second electrode 22, respectively. For example, the light emitting element 30 may be arranged so that one end thereof is placed on the first electrode 21 and the other end thereof is placed on the second electrode 22.

[0118] The light emitting element 30 may be provided with (e.g., including) a plurality of layers in a direction perpendicular (e.g., substantially perpendicular) to the upper surface of the first substrate 11 or the first planarization layer 19. The light emitting element 30 is arranged so that one extension direction is parallel (e.g., substantially parallel) to the upper surface of the first planarization layer 19, and a plurality of semiconductor layers included in the light emitting element 30 may be sequentially arranged in a direction parallel (e.g., substantially parallel) to the upper surface of the first planarization layer 19. However, the present disclosure is not limited thereto, and when the light emitting element 30 has a different structure, the plurality of semiconductor layers may be arranged in a direction perpendicular (e.g., substantially perpendicular) to the upper surface of the first planarization layer 19.

[0119] Both ends of the light emitting element 30 may contact the contact electrodes (CNE1 and CNE2), respectively. For example, the light emitting element 30 may not be provided with (eg, may not include) an insulating film ( Figure 4 38 in the insulating film 38), and a portion of the semiconductor layer may be exposed, and the exposed semiconductor layer may contact (e.g., physically contact) the contact electrodes (CNE1 and CNE2). However, the present disclosure is not limited thereto, and at least a portion of the insulating film 38 may be removed so that both side surfaces of the semiconductor layer may be partially exposed. The exposed side surface of the semiconductor layer may directly contact (e.g., physically contact) the contact electrodes (CNE1 and CNE2).

[0120] The second insulating layer PAS2 may be partially on the light emitting element 30. For example, the second insulating layer PAS2 may have a width less than the length of the light emitting element 30 and be on the light emitting element 30 so as to expose both ends of the light emitting element 30 while surrounding the light emitting element 30. During the process of manufacturing the display device 10, the second insulating layer PAS2 may cover the light emitting element 30, the electrodes (21 and 22), and the first insulating layer PAS1, and then may be removed to expose both ends of the light emitting element 30. The second insulating layer PAS2 may extend in the second direction DR2 on the first insulating layer PAS1 on a plane, thereby forming a linear or island pattern in each sub-pixel PXn. During the process of manufacturing the display device 10, the second insulating layer PAS2 may protect the light emitting element 30 and fix the light emitting element 30.

[0121] A plurality of contact electrodes ( CNE1 and CNE2 ) and a third insulating layer PAS3 may be on the second insulating layer PAS2 .

[0122] The plurality of contact electrodes (CNE1 and CNE2) may have a shape extending in one direction and may be on each of the electrodes (21 and 22). The contact electrodes (CNE1 and CNE2) may include a first contact electrode CNE1 on the first electrode 21 and a second contact electrode CNE2 on the second electrode 22. The contact electrodes (CNE1 and CNE2) may be spaced apart from each other or face each other. For example, the first contact electrode CNE1 and the second contact electrode CNE2 may be on the first electrode 21 and the second electrode 22, respectively, and may be spaced apart from each other in the first direction DR1. Each of the contact electrodes (CNE1 and CNE2) may form a stripe pattern in the emission area EMA of each sub-pixel PXn.

[0123] Each of the plurality of contact electrodes (CNE1 and CNE2) may contact (e.g., physically contact) the light emitting element 30. The first contact electrode CNE1 may contact (e.g., physically contact) one end of the light emitting element 30, and the second contact electrode CNE2 may contact (e.g., physically contact) the other end of the light emitting element 30. In the light emitting element 30, the semiconductor layer is exposed on both end surfaces in the extension direction, and the contact electrodes (CNE1 and CNE2) may be in electrical contact with the semiconductor layer of the light emitting element 30. One side of each of the contact electrodes (CNE1 and CNE2) in contact (e.g., physically contact) with both ends of the light emitting element 30 may be on the second insulating layer PAS2. The first contact electrode CNE1 may contact (e.g., physically contact) the first electrode 21 through an opening OP exposing a portion of the upper surface of the first electrode 21, and the second contact electrode CNE2 may contact (e.g., physically contact) the second electrode 22 through an opening OP exposing a portion of the upper surface of the second electrode 22.

[0124] The width of each of the contact electrodes (CNE1 and CNE2) measured in one direction may be smaller than the width of each of the electrodes (21 and 22) measured in one direction. Each of the contact electrodes (CNE1 and CNE2) may contact (e.g., physically contact) one end and the other end of the light emitting element 30 and cover a portion of the upper surface of each of the first electrode 21 and the second electrode 22. However, the present disclosure is not limited thereto, and the contact electrodes (CNE1 and CNE2) may be formed to have a greater width than the electrodes (21 and 22) to cover both sides of the electrodes (21 and 22).

[0125] The contact electrodes (CNE1 and CNE2) may include a transparent conductive material. For example, the contact electrodes (CNE1 and CNE2) may include ITO, IZO, ITZO, and / or aluminum (Al). Light emitted by the light emitting element 30 may pass through the contact electrodes (CNE1 and CNE2) and proceed toward the electrodes (21 and 22). However, the present disclosure is not limited thereto.

[0126] Although two contact electrodes ( CNE1 and CNE2 ) are shown in the drawings in one subpixel PXn, the present disclosure is not limited thereto. The number of contact electrodes ( CNE1 and CNE2 ) may be changed or varied depending on the number of electrodes ( 21 and 22 ) provided for each subpixel PXn.

[0127] The third insulating layer PAS3 may cover the first contact electrode CNE1. The third insulating layer PAS3 may include the first contact electrode CNE1 to cover the side on which the first contact electrode CNE1 is positioned based on the second insulating layer PAS2. The third insulating layer PAS3 may cover the side on which the first contact electrode CNE1 is positioned based on the second insulating layer PAS2 except the first contact electrode CNE1. For example, the third insulating layer PAS3 may cover the first contact electrode CNE1 and the first insulating layer PAS1 on the first electrode 21. Such an arrangement may be formed by partially removing the insulating material layer to form the second contact electrode CNE2 after the insulating material layer forming the third insulating layer PAS3 is completely placed in the light emitting area EMA. In the above process, the insulating material layer forming the third insulating layer PAS3 may be removed together with the insulating material layer forming the second insulating layer PAS2, and one side of the third insulating layer PAS3 may be aligned with one side of the second insulating layer PAS2. One side of the second contact electrode CNE2 may be on the third insulating layer PAS3, and the second contact electrode CNE2 may be insulated (eg, electrically insulated) from the first contact electrode CNE1 with the third insulating layer PAS3 therebetween.

[0128] The fourth insulating layer PAS4 may be entirely on the display area DPA of the first substrate 11. The fourth insulating layer PAS4 may play a role in protecting components on the first substrate 11 from the external environment. However, the fourth insulating layer PAS4 may be omitted.

[0129] Each of the first insulating layer PAS1, the second insulating layer PAS2, the third insulating layer PAS3, and the fourth insulating layer PAS4 described above may include an inorganic insulating material and / or an organic insulating material. For example, each of the first insulating layer PAS1, the second insulating layer PAS2, the third insulating layer PAS3, and the fourth insulating layer PAS4 may include an inorganic insulating layer, such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (AlOx), or the like. 2 O 3 ) and / or aluminum nitride (AlN). In some embodiments, each of the first insulating layer PAS1, the second insulating layer PAS2, the third insulating layer PAS3, and the fourth insulating layer PAS4 may include an organic insulating layer, such as acrylic resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, unsaturated polyester resin, polyphenylene resin, polyphenylene sulfide resin, benzocyclobutene resin, cardo resin, siloxane resin, silsesquioxane resin, polymethyl methacrylate, polycarbonate, and / or polymethyl methacrylate-polycarbonate synthetic resin. However, the present disclosure is not limited thereto.

[0130] Figure 4 is a schematic diagram of a light emitting element according to the embodiment.

[0131] The light emitting element 30 may be a light emitting diode. In some embodiments, the light emitting element 30 may be an inorganic light emitting diode having a size of micrometers to nanometers and made of an inorganic material. When an electric field is formed between two electrodes facing each other in a set or predetermined direction, the organic light emitting diode may be aligned between two electrodes having polarities (e.g., having respective polarities different from each other). The light emitting element 30 may be aligned between the two electrodes by an electric field formed on the two electrodes.

[0132] The light emitting element 30 may have a shape extending in one direction. The light emitting element 30 may have a shape of a cylinder, a rod, a wire, or a tube. However, the shape of the light emitting element 30 is not limited thereto, and the light emitting element 30 may have various suitable shapes, such as a cube, a cuboid, or a hexagonal prism, or may have a shape extending in one direction and having a partially inclined outer surface. A plurality of semiconductors included in the light emitting element 30, which will be further described herein below, may be arranged or stacked in sequence in one direction.

[0133] The light emitting element 30 may include a semiconductor layer doped with impurities of any conductivity type (eg, p-type or n-type). The semiconductor layer may receive an electrical signal applied by an external power source and emit light having a set or specific wavelength band.

[0134] refer to Figure 4The light emitting element 30 may include a first semiconductor layer 31 , a second semiconductor layer 32 , a light emitting layer 36 , an electrode layer 37 and an insulating film 38 .

[0135] The first semiconductor layer 31 may be an n-type semiconductor layer. When the light emitting element 30 emits light in a blue wavelength band, the first semiconductor layer 31 may include Al x Ga y In 1-x-y N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the semiconductor material may be at least one of AlGaInN, GaN, AlGaN, InGaN, AlN, and InN, each of which is doped with an n-type impurity. The first semiconductor layer 31 may be doped with an n-type dopant. The n-type dopant may be Si, Ge, or Sn. For example, the first semiconductor layer 31 may be n-GaN doped with n-type Si. The length of the first semiconductor layer 31 may be 1.5 μm to 5 μm, but is not limited thereto.

[0136] The second semiconductor layer 32 is on the light emitting layer 36, which will be further described herein below. The second semiconductor layer 32 may be a p-type semiconductor layer. When the light emitting element 30 emits light in a blue wavelength band or a green wavelength band, the second semiconductor layer 32 may include Al x Ga y In 1-x-y N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the semiconductor material may be at least one of AlGaInN, GaN, AlGaN, InGaN, AlN, and InN, each of which is doped with a p-type impurity. The second semiconductor layer 32 may be doped with a p-type dopant. The p-type dopant may be Mg, Zn, Ca, Se, or Ba. For example, the second semiconductor layer 32 may include p-GaN doped with p-type Mg. The length of the second semiconductor layer 32 may be 0.05 μm to 0.10 μm, but is not limited thereto.

[0137] Despite Figure 4 2 shows that each of the first semiconductor layer 31 and the second semiconductor layer 32 is formed as one layer, but the present disclosure is not limited thereto. Each of the first semiconductor layer 31 and the second semiconductor layer 32 may further include a larger number of layers, for example, a cladding layer or a tensile strain barrier reduction (TSBR) layer according to the material of the light emitting layer 36.

[0138] The light emitting layer 36 is between the first semiconductor layer 31 and the second semiconductor layer 32. The light emitting layer 36 may include a material of a single quantum well structure or a multiple quantum well structure. When the light emitting layer 36 includes a material of a multiple quantum well structure, the light emitting layer 36 may have a structure in which quantum layers and well layers are alternately stacked. According to an electrical signal applied through the first semiconductor layer 31 and the second semiconductor layer 32, the light emitting layer 36 may emit light by the combination (or recombination) of electron-hole pairs (e.g., by the formation of excitons). When the light emitting layer 36 emits light in a blue wavelength band, the light emitting layer 36 may include materials such as AlGaN and / or AlGaInN. In some embodiments, when the light emitting layer 36 has a multiple quantum well structure in which quantum layers and well layers are alternately stacked, the quantum layers may include materials such as AlGaN and / or AlGaInN, and the well layers may include materials such as GaN and / or AlInN. For example, the light emitting layer 36 includes quantum layers each containing AlGaInN and well layers each containing AlInN, and thus the light emitting layer 36 can emit blue light having a central wavelength band of 450 nm to 495 nm, as described above.

[0139] However, the present disclosure is not limited thereto, and the light emitting layer 36 may have a structure in which a semiconductor material having a high band gap energy and a semiconductor material having a low band gap energy are alternately stacked, and may contain other Group 3 to Group 5 semiconductor materials depending on the wavelength band of light. The light emitted by the light emitting layer 36 is not limited to light of a blue wavelength band, and in some cases, the light emitting layer 36 may emit light of a red wavelength band or a green wavelength band. The length of the light emitting layer 36 may have a range of 0.05 μm to 0.10 μm, but is not limited thereto.

[0140] In some embodiments, light emitted by the light emitting layer 36 may be emitted to both end surfaces of the light emitting element 30 as well as longitudinal outer surfaces of the light emitting element 30. The direction of light emitted by the light emitting layer 36 is not limited to one direction.

[0141] The electrode layer 37 may be an ohmic contact electrode. However, the present disclosure is not limited thereto, and the electrode layer 37 may be a Schottky contact electrode (e.g., an electrode formed by a junction of a semiconductor and a metal). The light emitting element 30 may include at least one electrode layer 37. Figure 4 3 shows that the light emitting element 30 includes one electrode layer 37, but the present disclosure is not limited thereto. In some cases, the light emitting element 30 may include a greater number of electrode layers 37, or the electrode layer 37 may be omitted. Even if the number of electrode layers 37 is changed or the light emitting element 30 further includes other structures, the description of the light emitting element 30 to be further described below in this document may also be applied in the same manner.

[0142] When the light emitting element 30 is electrically connected to the electrode or contact electrode in the display device 10 according to the embodiment, the electrode layer 37 can reduce the resistance between the light emitting element 30 and the electrode or contact electrode. The electrode layer 37 may include a conductive metal. For example, the electrode layer 37 may include at least one selected from aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO) and indium tin zinc oxide (ITZO). The electrode layer 37 may include a semiconductor material doped with n-type or p-type impurities. The electrode layer 37 may include the same (or substantially the same) material, and may include materials different from each other, but the present disclosure is not limited thereto.

[0143] The insulating film 38 may surround the outer surfaces of the semiconductor layer and the electrode layer described above. For example, the insulating film 38 may surround the outer surface of at least the light emitting layer 36, and may extend in one direction in which the light emitting element 30 extends. The insulating film 38 may play a role of protecting the member. For example, the insulating film 38 may be formed to surround the side surface of the member, and may be formed so that both ends of the light emitting element 30 in the length direction are exposed.

[0144] Despite Figure 4 3 shows that the insulating film 38 can extend in the length direction of the light emitting element 30 to cover the side surfaces from the first semiconductor layer 31 to the electrode layer 37, but the present disclosure is not limited thereto. The insulating film 38 may cover only the outer surface of the semiconductor layer and a portion of the light emitting layer 36, or only cover a portion of the outer surface of the electrode layer 37 to expose a portion of the outer surface of the electrode layer 37. The insulating film 38 may be formed to have a cross-sectional upper surface in a region adjacent to at least one end of the light emitting element 30.

[0145] The thickness of insulating film 38 may have a range of 10 nm to 1.0 μm, but is not limited thereto. In some embodiments, the thickness of insulating film 38 may be about 40 nm.

[0146] The insulating film 38 may include a material having insulating properties, such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum nitride (AlN), and / or aluminum oxide (Al 2 O 3 ). Therefore, the insulating film 38 can prevent (or reduce the possibility or extent of) a short circuit that may occur when the light-emitting layer 36 is in direct contact (e.g., physical contact) with an electrode through which an electrical signal is transmitted to the light-emitting element 30. In addition, because the insulating film 38 protects the light-emitting element 30 and the outer surface of the light-emitting layer 36, degradation of light emission efficiency can be prevented or reduced.

[0147] In addition, the outer surface of the insulating film 38 may be surface treated. The light emitting element 30 may be aligned by spraying onto the electrode in a state where the light emitting element 30 is dispersed in a set or predetermined ink. Here, the surface of the insulating film 38 may be hydrophobically treated or hydrophilically treated so as to keep the light emitting element 30 in a dispersed state without agglomerating with other adjacent light emitting elements 30 in the ink. For example, the outer surface of the insulating film 38 may be surface treated with a material such as stearic acid and / or 2,3-naphthalene dicarboxylic acid.

[0148] The length h of the light emitting element 30 may be 1 μm to 10 μm or 2 μm to 6 μm, and for example, 3 μm to 5 μm. The diameter of the light emitting element 30 may be 300 nm to 700 nm, and the aspect ratio of the light emitting element 30 may be 1.2 to 100. However, the present disclosure is not limited thereto, and the plurality of light emitting elements 30 included in the display device 10 may have different diameters according to the composition difference of the light emitting layer 36. In some embodiments, the diameter of the light emitting element 30 may be about 500 nm.

[0149] The shape and material of the light emitting element 30 are not limited to Figure 4 In some embodiments, light emitting element 30 can include a greater number of layers, or can have a different shape.

[0150] Figure 5 and Figure 6 is a schematic diagram of a light emitting element according to other embodiments.

[0151] First, refer to Figure 5 The light emitting element 30' according to the embodiment further includes a third semiconductor layer 33' between the first semiconductor layer 31' and the light emitting layer 36', and a fourth semiconductor layer 34' and a fifth semiconductor layer 35' between the light emitting layer 36' and the second semiconductor layer 32'. Figure 5 The light emitting element 30' and Figure 4 The light emitting element 30 is different in that a plurality of semiconductor layers (33', 34', 35') and a plurality of electrode layers (37a' and 37b') are further provided, and the light emitting layer 36' contains different elements. The light emitting element 30' also includes an insulating film 38'. Hereinafter, the repeated descriptions of those provided above may not be repeated here, and the differences will be mainly described.

[0152] exist Figure 4 In the light emitting element 30 of FIG. 1 , the light emitting layer 36 may contain nitrogen (N) to emit blue light or green light. Figure 5In the light-emitting element 30', the light-emitting layer 36' and the other semiconductor layers can be semiconductor layers each containing at least phosphorus (P). The light-emitting element 30' according to the embodiment can emit red light with a central wavelength band of 620nm to 750nm. However, it should be understood that the central wavelength band of red light is not limited to the range described above, and includes all suitable wavelength ranges that can be considered red in the art.

[0153] In some embodiments, the first semiconductor layer 31 ′ is an n-type semiconductor layer and may include an In x Al y Ga 1-x-y The first semiconductor layer 31' may include at least one selected from InAlGaP, GaP, AlGaP, InGaP, AlP, and InP doped with n-type impurities. For example, the first semiconductor layer 31' may include n-AlGaInP doped with n-type Si.

[0154] The second semiconductor layer 32 ′ is a p-type semiconductor layer and may include In x Al y Ga 1-x-y The second semiconductor layer 32' may include at least one selected from InAlGaP, GaP, AlGaNP, InGaP, AlP, and InP doped with p-type impurities. For example, the second semiconductor layer 32' may include p-GaP doped with p-type Mg.

[0155] The light emitting layer 36' may be between the first semiconductor layer 31' and the second semiconductor layer 32'. The light emitting layer 36' may include a material having a single quantum well structure or a multiple quantum well structure to emit light having a set or specific wavelength band. When the light emitting layer 36' has a multiple quantum well structure in which quantum layers and well layers are alternately stacked, the quantum layer may include a material such as AlGaP and / or AlInGaP, and the well layer may include a material such as GaP and / or AlInP. For example, the light emitting layer 36' may include a quantum layer including AlGaInP and a well layer including AlInP to emit red light having a central wavelength band of 620nm to 750nm.

[0156] Figure 5 The light emitting element 30' may include a cladding layer adjacent to the light emitting layer 36'. Figure 5 As shown in FIG. 1 , the third semiconductor layer 33 ′ and the fourth semiconductor layer 34 ′ between the first semiconductor layer 31 ′ and the second semiconductor layer 32 ′ and on and under the light emitting layer 36 ′ may be cladding layers.

[0157] The third semiconductor layer 33' may be between the first semiconductor layer 31' and the light emitting layer 36'. Like the first semiconductor layer 31', the third semiconductor layer 33' may be an n-type semiconductor layer and may include an In x Al y Ga 1-x-y The semiconductor material may be a semiconductor material having a chemical formula of P (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the first semiconductor layer 31 ′ may include n-AlGaInP, and the third semiconductor layer 33 ′ may include n-AlInP.

[0158] The fourth semiconductor layer 34' may be between the light emitting layer 36' and the second semiconductor layer 32'. Like the second semiconductor layer 32', the fourth semiconductor layer 34' may be a p-type semiconductor layer and may include a semiconductor layer having In x Al y Ga 1-x-y The semiconductor material of the chemical formula of P (0≤x≤1, 0≤y≤1, 0≤x+y≤1) is used. For example, the second semiconductor layer 32 ′ may include p-GaP, and the fourth semiconductor layer 34 ′ may include p-AlInP.

[0159] The fifth semiconductor layer 35' may be between the fourth semiconductor layer 34' and the second semiconductor layer 32'. Like the second semiconductor layer 32' and the fourth semiconductor layer 34', the fifth semiconductor layer 35' may be a p-type semiconductor layer. In some embodiments, the fifth semiconductor layer 35' may serve to reduce the difference in lattice constant between the fourth semiconductor layer 34' and the second semiconductor layer 32'. The fifth semiconductor layer 35' may be a tensile strain barrier reduction (TSBR) layer. For example, the fifth semiconductor layer 35' may include p-GaInP, p-AlInP and / or p-AlGaInP, but its material is not limited thereto. The length of each of the third semiconductor layer 33', the fourth semiconductor layer 34' and the fifth semiconductor layer 35' may be 0.08 μm to 0.25 μm, but is not limited thereto.

[0160] The first electrode layer 37a' and the second electrode layer 37b' may be on the first semiconductor layer 31' and the second semiconductor layer 32', respectively. The first electrode layer 37a' may be on the lower surface of the first semiconductor layer 31', and the second electrode layer 37b' may be on the upper surface of the second semiconductor layer 32'. However, the present disclosure is not limited thereto, and at least one of the first electrode layer 37a' and the second electrode layer 37b' may be omitted. For example, in the light emitting element 30', the first electrode layer 37a' may not be on the lower surface of the first semiconductor layer 31', and only one second electrode layer 37b' may be on the upper surface of the second semiconductor layer 32'.

[0161] Then, refer to Figure 6 , the light emitting element 30 ″ may have a shape extending in one direction, and may have a partially inclined side surface. For example, the light emitting element 30 ″ according to the embodiment may have a partially tapered shape.

[0162] The light emitting element 30" may be formed such that a plurality of layers are not stacked in one direction and each layer surrounds an outer surface of another layer. The light emitting element 30" may include a semiconductor core having at least some regions extending in one direction and an insulating film 38" formed to surround the semiconductor core. The semiconductor core may include a first semiconductor layer 31", a light emitting layer 36", a second semiconductor layer 32" and an electrode layer 37".

[0163] The first semiconductor layer 31″ may extend in one direction, and both end portions thereof may be formed to be inclined toward a center thereof. The first semiconductor layer 31″ may include a rod-shaped or cylindrical main body portion, and an upper end portion and a lower end portion having inclined side surfaces and respectively formed on and below the main body portion. The upper end portion of the main body portion may have a steeper slope than the lower end portion.

[0164] The light emitting layer 36" may surround the outer surface of the main body portion of the first semiconductor layer 31". The light emitting layer 36" may have a ring shape extending in one direction. The light emitting layer 36" may not be formed on the upper end portion and the lower end portion of the first semiconductor layer 31". However, the present disclosure is not limited thereto. The light emitted by the light emitting layer 36" may be emitted to both side surfaces of the light emitting element 30" in the length direction and to both ends of the light emitting element 30" in the length direction. Figure 4 Compared with the light emitting element 30, Figure 6 The light emitting element 30'' contains a light emitting layer 36'' having a large area and can therefore emit a larger amount of light.

[0165] The second semiconductor layer 32" may surround the outer surface of the light emitting layer 36" and the upper end portion of the first semiconductor layer 31". The second semiconductor layer 32" may include an annular main body portion extending in one direction and an upper end portion having an inclined side surface. For example, the second semiconductor layer 32" may directly contact (e.g., physically contact) the parallel side surfaces of the light emitting layer 36" and the inclined upper end portion of the first semiconductor layer 31". However, the second semiconductor layer 32" is not formed on the lower end portion of the first semiconductor layer 31".

[0166] The electrode layer 37" may surround the outer surface of the second semiconductor layer 32". The shape of the electrode layer 37" may be substantially the same as the shape of the second semiconductor layer 32". The electrode layer 37" may completely contact (eg, completely physically contact) the outer surface of the second semiconductor layer 32".

[0167] The insulating film 38" may surround the outer surfaces of the electrode layer 37" and the first semiconductor layer 31". The insulating film 38" may directly contact (e.g., physically contact) the lower end portion of the first semiconductor layer 31" and the exposed lower portions of the light emitting layer 36", the second semiconductor layer 32", and the electrode layer 37".

[0168] The light emitting element 30 may be sprayed on each of the electrodes (21 and 22) by an inkjet printing process. The light emitting element 30 may be dispersed in a solvent to prepare an ink state and sprayed on the electrodes (21, 22), and may be between the electrodes (21 and 22) by a process of applying an alignment signal to the electrodes (21 and 22). When an alignment signal is applied to each of the electrodes (21 and 22), an electric field is formed thereon, and the light emitting element 30 may receive a dielectrophoretic force by the electric field to align the light emitting element 30. The light emitting element 30 that has received the dielectrophoretic force may be on the first electrode 21 and the second electrode 22 while changing the alignment direction and position.

[0169] The light emitting element 30 may include a plurality of semiconductor layers, and may generally be made of a material having a specific gravity greater than that of a solvent. When the light emitting element 30 is dispersed and stored in a solvent, the dispersion may be maintained for a set or predetermined period of time, and then gradually precipitated due to the specific gravity difference. When the light emitting element 30 is precipitated in the solvent, the number of light emitting elements 30 per ink droplet is not uniform. Therefore, when a device including the light emitting element 30 is manufactured using the ink, the number of light emitting elements 30 for each region is not constant, and therefore, the quality of the product may be deteriorated or reduced.

[0170] According to the embodiment, the ink containing the light emitting element 30 further contains a thickener ( Figure 7 500 in), and therefore, the viscosity of the ink can vary according to the shear stress applied to the solution. The ink comprising the light-emitting element 30 has a high viscosity in a state where the ink is stored in a container or in a state where shear stress is not applied thereto, and therefore, the light-emitting element 30 can be stored for a long time in a dispersed state. In addition, the ink comprising the light-emitting element 30 has a low viscosity in a state where the ink is discharged through a nozzle during inkjet printing or in a state where shear stress is applied thereto, and therefore, the ink can be easily discharged through a nozzle. Therefore, according to an embodiment, the ink comprising the light-emitting element 30 can be sprayed by including a uniform number of light-emitting elements 30 per unit area throughout the printing process, while preventing or reducing the precipitation of the light-emitting element 30. Hereinafter, the ink comprising the light-emitting element 30 will be further described.

[0171] Figure 7 is a schematic diagram of a light emitting element ink according to the embodiment.

[0172] refer to Figure 7 The light emitting element ink 1000 according to the embodiment includes a light emitting element solvent 100, a light emitting element 30 dispersed in the light emitting element solvent 100, and a thickener 500. The light emitting element 30 may be selected from the above reference Figures 4 to 6 Any of the light emitting elements (30, 30' and 30") described and illustrated in the accompanying drawings Figure 4 Since the description of the light emitting element 30 is the same as described above, the light emitting element solvent 100 and the thickener 500 will be described in more detail herein below.

[0173] The light-emitting element solvent 100 can store (or dissolve) the light-emitting element 30 having a high specific gravity including a semiconductor layer in a dispersed state, and can be an organic solvent that does not react with the light-emitting element 30 (or substantially does not react with the light-emitting element 30). The light-emitting element solvent 100 can have a viscosity suitable for or sufficient to be discharged in a liquid state through the nozzle of the inkjet printing device. The solvent molecules of the light-emitting element solvent 100 can disperse the light-emitting element 30 while surrounding the light-emitting element 30 on its surface. The light-emitting element ink 1000 can contain the light-emitting element 30 prepared in a solution or colloid state. In an embodiment, examples of the light-emitting element solvent 100 may include, but are not limited to, acetone, water, alcohol, toluene, propylene glycol (PG), propylene glycol methyl acetate (PGMA), triethylene glycol monobutyl ether (TGBE), diethylene glycol monophenyl ether (DGPE), amide-based solvents, dicarbonyl-based solvents, diethylene glycol dibenzoate, tricarbonyl-based solvents, triethyl citrate, phthalate-based solvents, butyl benzyl phthalate, bis (2-ethylhexyl) phthalate, bis (2-ethylhexyl) isophthalate, and ethyl phthaloyl ethyl glycolate.

[0174] In the present specification, "light-emitting element solvent 100" refers to a solvent or a medium thereof in which the light-emitting element 30 can be dispersed, and "solvent molecule 101" refers to a molecule constituting the light-emitting element solvent 100. As will be further described herein below, it can be understood that the "light-emitting element solvent 100" is a liquid medium containing the solvent molecule 101. However, these terms may not necessarily be used separately, and in some cases, the "light-emitting element solvent 100" and the "solvent molecule 101" may be used interchangeably, but may be substantially the same.

[0175] The thickener 500 may be dispersed in the light emitting element solvent 100 together with the light emitting element 30. A set or predetermined amount of the thickener 500 is included in the light emitting element ink 1000 to change the viscosity of the solution according to the state of the light emitting element ink 1000. According to the embodiment, the thickener 500 may include a functional group capable of forming a hydrogen bond to form an intermolecular hydrogen bond. The thickener 500 may form a hydrogen bond between the solvent molecules 101 of the light emitting element solvent 100 or between the thickeners 500 to form a relatively strong attraction between different molecules. For example, a compound of the thickener 500 may be hydrogen bonded to a compound of the solvent or another compound of the thickener 500.

[0176] Figure 8 It is shown in Figure 7 Schematic diagram of the bond between the thickener and the light-emitting element solvent in the storage state of part A of the light-emitting element ink. Figure 8 The form of molecules of the thickener 500 dispersed in the light emitting element solvent 100 in a state in which shear stress is not applied to the light emitting element is illustrated.

[0177] refer to Figure 8 The thickener may include a first functional group (e.g., a hydroxyl group (-OH) and / or an amine group (-NH 2 ), which contains hydrogen (H) as a functional group capable of forming a hydrogen bond and a second functional group (e.g., a carbonyl group (-CO-), an ester group (-COO-), an amine group (-NH-), an amide group (-CONH-), a urea group (-NHCONH-) and / or a carbamate group (-NHCOO-)) as a functional group capable of forming a hydrogen bond with hydrogen (H) contained in another molecule. Although the thickener 500 is shown in the drawings to contain a hydroxyl group (-OH) as a first functional group and an ester group (-COO-) as a second functional group, and the solvent molecule 101 of the light emitting element solvent 100 contains glycol ether (-OCH 2 CH 2 O-) group, but the disclosure is not limited thereto.

[0178] The thickener 500 may include a main chain portion CP in which a first functional group and a second functional group are bonded, and the main chain portion CP may be bonded to the first functional group and the second functional group. The main chain portion CP may be a carbon chain, such as an alkyl group, an alkenyl group and / or an alkynyl group, but is not limited thereto, and may further include other functional groups, such as an ether group (-O-). In one thickener 500, a first functional group including hydrogen (H) may form a hydrogen bond HB1 with an atom having a non-covalent electron pair (e.g., oxygen (O) or nitrogen (N)) of a solvent molecule 101 of a light-emitting element solvent 100 or a second functional group of the thickener 500. The second functional group of the thickener 500 may form a hydrogen bond HB2 with a first functional group of another thickener 500. According to the embodiment, one molecule of the thickener 500 may form a hydrogen bond with another molecule (e.g., compound) of the thickener 500 and / or a molecule (e.g., compound) of the solvent molecule 101, and a network structure may be formed between the main chain portion CP and the solvent molecule 101 and between the main chain portions CP of other thickeners 500 in a state where shear stress is not applied. Due to the network structure formed by the thickener 500, the light-emitting element ink 1000 may have a high viscosity, and in the storage state of the light-emitting element ink 1000, the precipitation rate of the light-emitting element 30 may be reduced.

[0179] For example, the light-emitting element ink 1000 may have a viscosity of 30 cP to 300 cP measured at room temperature (25° C.) in a state where no shear stress is applied. However, the present disclosure is not limited thereto. The viscosity of the light-emitting element ink 1000 may be adjusted as needed or desired by the molecular structure and / or molecular weight of the thickener 500. However, in order to prevent or reduce precipitation of the light-emitting element 30, the light-emitting element ink 1000 may have a viscosity of at least 30 cP or greater than 30 cP in a state where no shear stress is applied. In the light-emitting element ink 1000, the light-emitting element 30 may be maintained in a dispersed state for a long time until the printing process using an inkjet printing device.

[0180] According to the embodiment, the thickener 500 of the light emitting element ink 1000 may include a compound represented by Chemical Formula 1 below.

[0181] Chemical formula 1

[0182]

[0183] In the above chemical formula 1, R 1 are each independently a substituted or unsubstituted alkylene group having 6 to 8 carbon atoms, a substituted or unsubstituted alkenylene group having 6 to 8 carbon atoms, or a substituted or unsubstituted alkynylene group having 6 to 8 carbon atoms, and R 2Each independently is an alkyl group having 3 to 8 carbon atoms. The compound of Chemical Formula 1 includes a triester group formed by bonding the -OH group of glycerol to ricinoleic acid. The thickener 500 according to the embodiment may have a structure in which a plurality of carbon chains each containing an alcohol (-OH) group capable of forming a hydrogen bond are bonded to each other. In the thickener 500, the carbon chains each containing an alcohol (-OH) group may be bonded to each other by a triester group, and the hydroxyl group (-OH) contained in ricinoleic acid and the oxygen atom of the triester group may form a hydrogen bond with different molecules (e.g., other compounds). For example, the hydroxyl group (-OH) of ricinoleic acid may form a hydrogen bond HB1 with oxygen (O) contained in the solvent molecule 101 of another thickener 500 or a light-emitting element solvent 100, and the double bond oxygen (=O) of the triester group may form a hydrogen bond HB2 with the hydroxyl group (-OH) of another thickener 500. In a storage state in which shear stress is not applied, the thickener 500 may form a network structure through hydrogen bonds between molecules, and the light emitting element ink 1000 may have high viscosity.

[0184] In the above chemical formula 1, R 1 and R 2 It may be changed variously depending on the molecular weight of the thickener 500, etc. For example, R 1 It may be an unsubstituted alkylene group having 6 to 8 carbon atoms, an alkenylene group having several double bonds, or an alkylene group having 6 to 8 carbon atoms and substituted by a halogen group, an ethoxy group, a thiol group, or a thioalkylethanol group. In an exemplary embodiment, the thickener 500 may include a compound represented by any one selected from the following Chemical Formulas 2 to 6.

[0185] Chemical formula 2

[0186]

[0187] Chemical formula 3

[0188]

[0189] Chemical formula 4

[0190]

[0191] Chemical formula 5

[0192]

[0193] Chemical formula 6

[0194]

[0195] In the above chemical formula 4, R 3 Yes*-(CH2 CH 2 O) x CH 3 (Here, x is an integer from 7 to 112, and *- means a bond with an oxygen atom (O)).

[0196] Chemical formula 2 shows an example in which R of chemical formula 1 1 is an embodiment of an unsubstituted alkenylene group, and Formulas 3 to 6 illustrate embodiments in which R of Formula 1 1 It is bromine (Br), thiol (-SH), sulfanyl alcohol (-SHCH 2 CH 2 OH) or ethoxy (-(CH 2 CH 2 O)xCH 3 ) substituted alkenylene group. In addition, Chemical Formulas 3 to 6 illustrate embodiments in which R of Chemical Formula 1 2 is an embodiment of an unsubstituted alkyl group having 6 carbon atoms. Chemical Formulas 3 to 6 may each have a structure in which a plurality of carbon chains each including an alcohol group are connected to each other through a triester group and each of the carbon chains is substituted with another functional group. However, the structure of the thickener 500 is not limited to Chemical Formulas 2 to 6. If the thickener 500 has a structure in which a plurality of carbon chains each including an alcohol group are connected to each other within the disclosed range, then R of Chemical Formula 1 1 and R 2 The type (or composition) of and the substituent bonded thereto may be varied variously. In addition, in the above Chemical Formula 4, x may be any one selected from 7 to 112, for example, x may be any one selected from 7, 12, 16, 44 and 112.

[0197] In some embodiments, when the light-emitting element ink 1000 is discharged through a nozzle or flows in an inkjet head of an inkjet printing device, shear stress may be applied to the solvent 100. The shear stress may have a stronger strength than the intermolecular hydrogen bonds of the thickener 500, and the hydrogen bonds (HB1 and HB2) may be broken. The thickener 500 does not form a network structure with the solvent molecules 101 of the light-emitting element solvent 100 or other thickeners 500, and thus the light-emitting element ink 1000 may have a low viscosity. For example, applying shear stress to the light-emitting element ink 1000 may break, destroy or cleave the respective intermolecular hydrogen bonds between the compounds of the thickener and the compounds of the light-emitting element solvent and / or other compounds of the thickener, so that the respective intermolecular hydrogen bonds no longer exist to form a network structure.

[0198] Fig. 9 It is shown in Figure 7Schematic diagram of the bond between the thickener and the light-emitting element solvent in the printed state of part A of the light-emitting element ink. Fig. 9 The form of molecules of the thickener 500 ′ dispersed in the light emitting element solvent 100 in a state where shear stress is applied when the light emitting element ink 1000 is printed is illustrated.

[0199] refer to Fig. 9 , during the printing process of the light-emitting element ink 1000, when the light-emitting element ink 1000 flows into or out of the inkjet head of the inkjet printing device or is discharged through the nozzle of the inkjet printing device, shear stress can be applied to the light-emitting element solvent 100. In the present specification, "printing" of the light-emitting element 30 may mean discharging or spraying the light-emitting element 30 to a set or predetermined object using an inkjet printing device. For example, "printing" of the light-emitting element 30 may mean that the light-emitting element 30 is directly discharged through the nozzle of the inkjet printing device, or is discharged in a state in which the light-emitting element 30 is dispersed in the light-emitting element ink 1000. However, the present disclosure is not limited thereto, and "printing" of the light-emitting element 30 may mean spraying the light-emitting element 30 or the light-emitting element ink 1000 in which the light-emitting element 30 is dispersed onto a target substrate ( Fig.11 to allow the light emitting element 30 or the light emitting element ink 1000 to be mounted on the target substrate SUB.

[0200] When the light-emitting element ink 1000 is discharged through the nozzle of the inkjet printing device or in a state where shear stress is applied thereto, the thickener 500' may not form a network structure. The shear stress applied during the printing process of the light-emitting element ink 1000 may have a stronger strength than each of the intermolecular hydrogen bonds (HB1 and HB2) formed by the thickener 500', and the thickener 500' and the solvent molecules 101 of the light-emitting element solvent 100 may be dispersed separately without forming a network structure.

[0201] According to the embodiment, the light-emitting element ink 1000 may have a viscosity of 5cP to 15cP or 7cP to 13cP, for example, about 10cP, measured at room temperature (25°C) in a state where shear stress is applied. However, the present disclosure is not limited thereto, and the viscosity of the light-emitting element ink 1000 may be changed variously as long as the light-emitting element ink 1000 can be discharged through the nozzle of the inkjet head. When the light-emitting element ink 1000 has a viscosity within the above range, the light-emitting element ink 1000 can be easily discharged through the nozzle, and the dispersion of the light-emitting element 30 can be maintained because the printing process is previously performed even if the light-emitting element 30 is gradually precipitated. For example, the number of light-emitting elements 30 of the light-emitting element ink 1000 per unit droplet discharged from the nozzle of the inkjet printing device can be kept uniform.

[0202] The light-emitting element ink 1000 may contain a set or predetermined amount of the light-emitting element 30 per unit weight, and may contain a thickener 500' in a set or predetermined content relative to the weight of the light-emitting element 30. According to the embodiment, the light-emitting element ink 1000 may contain 100 to 500 parts by weight of the thickener 500' relative to 100 parts by weight of the light-emitting element 30. When the thickener 500' is contained in an amount less than 100 parts by weight relative to 100 parts by weight of the light-emitting element 30, the effect of preventing or reducing the precipitation of the light-emitting element 30 in the storage state may be insufficient or inappropriate, and when the thickener 500' is contained in an amount of 500 parts by weight or more than 500 parts by weight, the viscosity of the light-emitting element ink 1000 is too high, and therefore, the nozzle inlet may be blocked during the printing process. When the light-emitting element ink 1000 contains the thickener 500' within the above range, the light-emitting element ink 1000 can be discharged smoothly through the nozzle while preventing or reducing the precipitation of the light-emitting element 30.

[0203] The content of the light-emitting element 30 contained in the light-emitting element ink 1000 may be changed or varied depending on the number of light-emitting elements 30 per unit droplet of the light-emitting element ink 1000 discharged through the nozzle during the printing process. In the embodiment, the light-emitting element 30 may be contained in an amount of 0.01 to 1 parts by weight relative to 100 parts by weight of the light-emitting element ink 1000. However, this is an example, and the content of the light-emitting element 30 may vary depending on the number of light-emitting elements 30 per unit droplet of the light-emitting element ink 1000.

[0204] The light emitting element ink 1000 may further include a dispersant that improves the dispersion of the light emitting element 30. The type or composition of the dispersant is not particularly limited, and the dispersant may be added in an appropriate or suitable amount to further disperse the light emitting element 30. For example, the dispersant may be included in an amount of 10 to 50 parts by weight relative to 100 parts by weight of the light emitting element 30. However, the content of the dispersant is not limited thereto.

[0205] According to the embodiment, the light emitting element ink 1000 may contain a thickener 500 to change the viscosity of the light emitting element ink 1000 during the process of manufacturing the display device 10. The light emitting element ink 1000 may have a suitable viscosity for each storage stage of the light emitting element ink 1000 and each printing stage through the nozzle. In some embodiments, in the storage stage of the light emitting element ink 1000, since the light emitting element ink 1000 has a high viscosity, precipitation of the light emitting element 30 can be prevented or reduced, and in the printing stage through the nozzle, since the light emitting element ink 1000 has a low viscosity, the printing process of the light emitting element 30 can be smoothly performed.

[0206] When a product including the light emitting element 30 is manufactured using the light emitting element ink 1000 according to the embodiment, a uniform number of light emitting elements 30 can be provided per unit area, and the light emitting element solvent 100 and the thickener 500 remaining as foreign matter in a subsequent process can be completely removed. Therefore, the reliability of the product including the light emitting element 30 can be improved. According to the embodiment, the above reference Figures 1 to 3 The display device 10 described can be manufactured using the light emitting element ink 1000 .

[0207] In the process of manufacturing the display device 10 , a process of placing the light emitting element 30 on the electrodes ( 21 and 22 ) may be performed, and the process may be formed by a printing process using the light emitting element ink 1000 .

[0208] Hereinafter, a process of manufacturing the display device 10 according to an exemplary embodiment will be described with reference to the accompanying drawings.

[0209] Fig.10 is a flowchart illustrating a method of manufacturing a display device according to the embodiment.

[0210] refer to Fig.10 According to the embodiment, the method for manufacturing the display device 10 includes the following effective actions: preparing a light-emitting element ink 1000 containing a light-emitting element 30, a light-emitting element solvent 100 and a thickener 500 (S100); preparing a target substrate SUB provided with (for example, including) a plurality of electrodes (21 and 22) and spraying the light-emitting element ink 1000 on the electrodes (21 and 22) (S200); forming an electric field on the electrodes (21 and 22) to place the light-emitting element 30 on the electrodes (21 and 22) (S300); and heat-treating the light-emitting element ink 1000 in a low-pressure environment to remove the light-emitting element solvent 100 and the thickener 500 (S400).

[0211] The process of manufacturing the display device 10 includes: an effective action of storing the light-emitting element ink 1000 having high viscosity without precipitation of the light-emitting element 30 in a state where shear stress is not applied; and an effective action of printing the light-emitting element ink 1000 containing the light-emitting element 30 having low viscosity in a state where shear stress is applied. In the light-emitting element ink 1000, the viscosity can be changed during the storage stage and the printing stage, and the light-emitting element ink 1000 can be easily printed on the target substrate SUB while preventing or reducing precipitation of the light-emitting element 30. Hereinafter, the method of manufacturing the display device 10 will be described in more detail with reference to the accompanying drawings.

[0212] Figures 11 to 13 is a cross-sectional view illustrating effective actions in a process of manufacturing a display device according to the embodiment.

[0213] First, refer to Fig.11 , a light-emitting element ink 1000 including a light-emitting element 30, a light-emitting element solvent 100, and a thickener 500, and a target substrate SUB provided with (e.g., including) a first electrode 21 and a second electrode 22 are prepared. Although a pair of electrodes is shown on the target substrate SUB in the drawings, a greater number of electrode pairs may be on the target substrate SUB. In some embodiments, in addition to the first substrate 11, the target substrate SUB may include a plurality of circuit elements on the first substrate 11 of the display device 10. Hereinafter, for ease of description, these circuit elements will be omitted.

[0214] The light-emitting element ink 1000 may include a light-emitting element solvent 100, a light-emitting element 30 dispersed in the light-emitting element solvent 100, and a photodegradable thickener 500. The light-emitting element ink 1000 stored in the container may be in a state where there is no (or substantially no) fluid flow and no shear stress is applied. The thickener 500 may form hydrogen bonds between molecules (e.g., compounds of the thickener 500) to form a three-dimensional network structure in the light-emitting element solvent 100. The light-emitting element ink 1000 may have a high viscosity, for example, 30 cp to 300 cp, and the light-emitting element 30 may be maintained in a dispersed state for a long time.

[0215] The effective action of preparing the light-emitting element ink 1000 can be carried out by mixing the light-emitting element 30, the light-emitting element solvent 100 and the dispersant to prepare the first dispersion process of the solution and adding the thickener 500 to the second dispersion process of the solution prepared in the first dispersion process. For example, the first dispersion process is carried out by mixing the light-emitting element 30 and the dispersant with the light-emitting element solvent 100, and then stirring the solution for 5 minutes or more. As described above, the light-emitting element 30 may have a diameter of 1 μm or less than 1 μm, or 500nm or less than 500nm, and a length of 1 μm to 10 μm or about 4 μm or more than 4 μm. Relative to 100 parts by weight of the light-emitting element ink 100, the light-emitting element 30 may be included in an amount of 0.01 parts by weight to 1 part by weight, and relative to 100 parts by weight of the light-emitting element 30, the dispersant may be included in an amount of 10 parts by weight to 50 parts by weight. The mixing process may be carried out by an ultrasonic process, a stirring process, a grinding process, etc.

[0216] Subsequently, a second dispersion process is performed in which the thickener 500 is further added to the solution prepared in the first dispersion process and mixed therewith. The thickener 500 may be included in an amount of 10 to 50 parts by weight relative to 100 parts by weight of the light-emitting element 30. The mixing process may be performed by sequentially performing an ultrasonic process and a stirring process for 5 minutes or more, respectively. In order to make the thickener 500 easy to mix, the mixing process may be performed at a temperature higher than room temperature (25°C) (e.g., at about 40°C or higher).

[0217] The light-emitting element ink 1000 prepared by the first dispersion process and the second dispersion process can be stored at room temperature (25° C.). The compound of the thickener 500 of the light-emitting element ink 1000 can form an intermolecular hydrogen bond with the compound of the light-emitting element solvent 100 and / or another compound of the thickener 500, and the light-emitting element ink 1000 can have a viscosity of at least 30 cP or more. The light-emitting element 30 can be maintained in a dispersed state with little precipitation.

[0218] Then, refer to Fig.12 and Fig.13 , the light emitting element ink 1000 is sprayed on the first electrode 21 and the second electrode 22 on the target substrate SUB. In the embodiment, the light emitting element ink 1000 can be sprayed on the electrodes (21 and 22) by a printing process using an inkjet printing device. The light emitting element ink 1000 can be ejected by a nozzle of an inkjet head included in the inkjet printing device. The light emitting element ink 1000 can flow along an internal flow path provided in the inkjet head and be discharged onto the target substrate SUB through the nozzle. The light emitting element ink 1000 discharged from the nozzle can be attached to the electrodes (21 and 22) on the target substrate SUB. The light emitting element 30 can have a shape extending in one direction, and can be dispersed in the light emitting element ink 1000 in a state where the extending direction has a random alignment direction.

[0219] Before the light-emitting element ink 1000 is ejected through the nozzle, a third dispersion process for redispersing the light-emitting element 30 and the thickener 500 may be performed. For example, the stored light-emitting element ink 1000 may be subjected to an ultrasonic process and / or a vortex and / or a stirring process for 5 minutes or more, respectively. Even if the light-emitting element ink 1000 has a high viscosity, and therefore, the light-emitting element 30 is hardly precipitated, a third dispersion process for properly or sufficiently dispersing the light-emitting element 30 may be performed before the printing process through the nozzle. Therefore, the light-emitting element 30 of the light-emitting element ink 1000 prepared in the inkjet printing apparatus may have a level of dispersion similar to that of the initial storage state.

[0220] When the light-emitting element ink 1000 is prepared in an inkjet printing apparatus and discharged through a nozzle, shear stress may be applied in a state where there is a flow of a fluid (the light-emitting element ink 1000). In the light-emitting element ink 1000 to which shear stress is applied, the thickener 500 does not form an intermolecular hydrogen bond, and the thickener 500' does not form a three-dimensional network structure, and each chain may exist in a dispersed state in the light-emitting element solvent 100. The light-emitting element ink 1000 may have a low viscosity, for example, a viscosity of about 5 cp to 15 cp, or about 10 cp, and may be easily discharged from the nozzle to prevent or reduce nozzle clogging due to the viscosity of the solution.

[0221] Fig.14 This is a diagram illustrating how the viscosity changes due to the application of shear stress to the light emitting element ink. Fig.14 The example shows the method of adding a thickener 500 to a light emitting element ink ( Fig.14 Sample #1 in the example, Sample 1 below) and a light emitting element ink not containing the thickener 500 ( Fig.14 Sample #2 in the figure, Sample 2 below) applied shear stress (shear rate, sec -1 )'s strength and viscosity change.

[0222] refer to Fig.14 , each of Sample 1 (Sample #1) and Sample 2 (Sample #2) has a high intensity of shear stress ( Fig.14 When the intensity of the shear stress applied to sample 1 (sample #1) and sample 2 (sample #2) is about 1000 seconds -1 When the viscosity thereof is about 8 cP to 10 cP, the solution having a viscosity within the above range can be easily discharged through the nozzle, and the nozzle is not blocked due to the viscosity of the solution.

[0223] In contrast, Sample 1 (Sample #1) and Sample 2 (Sample #2) have low shear stress intensity ( Fig.14 The viscosity can be different under the "low shear stress" state. When the shear stress intensity is about 0.1 seconds -1 When the thickness of the sample 1 (sample #1) is 200 μm, the viscosity of the sample 1 (sample #1) can be 30 cP or more (e.g., about 250 cP) because the thickener 500 forms a three-dimensional network structure. The light-emitting element 30 contained in the sample 1 (sample #1) is hardly precipitated and can maintain the initial dispersion state. Since the sample 2 (sample #2) does not contain the thickener 500, when the intensity of the shear stress is about 0.1 seconds, the light-emitting element 30 can be dispersed in the sample 1 (sample #1). -1 When , sample 2 (sample #2) may have a viscosity of about 10 cP. The light emitting element 30 included in sample 2 (sample #2) may precipitate over time without maintaining the initial dispersion state.

[0224] When the printing process is performed using sample 2 (sample #2), the light-emitting element 30 may precipitate, so that the number of light-emitting elements 30 contained in the solution per unit droplet may be less than the calculated value or may not be uniform per unit droplet. In contrast, when the printing process is performed using sample 1 (sample #1), the light-emitting element 30 is dispersed, there is almost no precipitation, and the number of light-emitting elements 30 contained per unit droplet can be uniform for each unit droplet. In the method for manufacturing a display device 10 according to the embodiment, the display device 10 is manufactured using the light-emitting element ink 1000 of sample 1 (sample #1), and the manufactured display device 10 has a uniform number of light-emitting elements 30 provided per unit area, so that product reliability can be improved.

[0225] Subsequently, an electric field is formed in the light emitting element ink 1000 to place the light emitting element 30 on the electrodes ( 21 and 22 ), and the light emitting element solvent 100 and the thickener 500 are removed ( S400 ).

[0226] Figures 15 to 17 is a cross-sectional view illustrating other effective actions in a process of manufacturing a display device according to the embodiment.

[0227] First, refer to Fig.15 When the light emitting element ink 1000 including the light emitting element 30 is ejected on the target substrate SUB, an alignment signal AC is applied to the electrodes (21 and 22) to generate an electric field EL on the target substrate SUB. The light emitting element 30 dispersed in the light emitting element solvent 100 may be subjected to a dielectrophoretic force by the electric field EL and may be arranged on the electrodes (21 and 22) while changing the alignment direction and position.

[0228] When the electric field EL is generated on the target substrate SUB, the light emitting element 30 may be subjected to a dielectrophoretic force. When the electric field EL generated on the target substrate SUB is generated parallel to (e.g., substantially parallel to) the upper surface of the target substrate SUB, the extension direction of the light emitting element 30 is aligned to be parallel to (e.g., substantially parallel to) the target substrate SUB, so that the light emitting element 30 may be arranged on the first electrode 21 and the second electrode 22. The light emitting element 30 may be moved toward the electrodes (21 and 22) from the initial scattered position by the dielectrophoretic force, respectively. Both ends of the light emitting element 30 may be on the first electrode 21 and the second electrode 22, while changing the position and alignment direction by the electric field EL. The light emitting element 30 may include a semiconductor layer doped with different conductivity types, and may have a dipole moment therein. When the light emitting element 30 having a dipole moment is placed on the electric field EL, the light emitting element 30 may be subjected to a dielectrophoretic force so that both ends thereof are on the electrodes (21 and 22), respectively.

[0229] The "alignment degree" of the light emitting element 30 may refer to the deviation of the alignment direction and the mounting position of the light emitting element 30 aligned on the target substrate SUB. For example, when the deviation of the alignment direction and the mounting position of the light emitting element 30 is large, it can be understood that the alignment degree of the light emitting element 30 is low, and when the deviation of the alignment direction and the mounting position of the light emitting element 30 is small, it can be understood that the alignment degree of the light emitting element 30 is high or improved.

[0230] However, during the process of manufacturing the display device 10, after the light emitting element 30 is between the electrodes (21 and 22), a process of removing the light emitting element solvent 100 and the thickener 500 by applying heat or light to the light emitting element ink 1000 may be performed. The light emitting element ink 1000 ejected on the electrodes (21 and 22) may be in a state where shear stress is not applied, and the light emitting element ink 1000 may have a high viscosity due to intermolecular hydrogen bonding of the thickener 500. Therefore, the light emitting element solvent 100 and the thickener 500 may not be easily removed and may remain as foreign matter on the electrodes (21 and 22) and / or the light emitting element 30. In addition, since the light emitting element ink 1000 has a high viscosity, the strength of the dielectrophoretic force acting on the light emitting element 30 by the electric field formed on the electrodes (21 and 22) may be insufficient or inappropriate. In addition, high-temperature heat treatment may be required to remove the light-emitting element solvent 100 and the thickener 500, each of which has a large viscosity, and the initial alignment state of the light-emitting element 30 may be changed by the attraction caused by the flow of the fluid or the attraction between the thickener 500 and the light-emitting element 30 while removing the light-emitting element solvent 100 and the thickener 500.

[0231] In the method of manufacturing the display device 10 according to the embodiment, the light emitting element solvent 100 and the thickener 500 may be completely removed through a heat treatment process under a low pressure environment.

[0232] refer to Fig.16 and Fig.17, the process of removing the light-emitting element solvent 100 and the thickener 500' can be performed in a chamber VCD capable of adjusting the internal pressure. In the chamber VCD, the internal pressure in the device can be adjusted, and the target substrate SUB can be heated in a state where the internal pressure is adjusted so as to remove the light-emitting element solvent 100 and the thickener 500'. In a state where the light-emitting element 30 is on the electrodes (21 and 22) by the electric field EL, no shear stress is applied to the thickener 500', and the thickener 500' can form intermolecular hydrogen bonds. When the light-emitting element solvent 100 and the thickener 500' are removed by heat treatment, in addition to the energy for volatilizing their respective molecules, energy for removing the hydrogen bonds between the molecules of the light-emitting element solvent 100 and the thickener 500' may be further required. In this case, the heat treatment process should be performed at a temperature higher than the boiling point of each molecule, and the high-temperature heat treatment process may damage the circuit layer of the display device 10.

[0233] In the method of manufacturing the display device 10, the light emitting element solvent 100 and the thickener 500' may be heat-treated in a low pressure environment even at a temperature lower than the boiling point of the light emitting element solvent 100 and the thickener 500' to completely remove the light emitting element solvent 100 and the thickener 500'. According to the embodiment, the process of removing the light emitting element solvent 100 and the thickener 500' may be performed in 10 -4 The heat treatment process is carried out at a pressure of 200 to 100 torr and a temperature of 25°C to 150°C. When the heat treatment process is carried out within the above pressure range, the boiling points of the thickener 500' and the light-emitting element solvent 100 can be reduced, and the hydrogen bonds therebetween can be more easily removed. For example, when the thickener 500' is a compound containing a triester group as in Chemical Formula 1, its boiling point can be 200°C or higher and about 313°C. However, even at a temperature range of 150°C or lower, the thickener 500' and the light-emitting element solvent 100 can be easily removed in the chamber VCD under a low pressure environment as described above. The heat treatment process in the chamber VCD can be carried out for 1 minute to 30 minutes. However, it is not limited thereto.

[0234] Since the process of removing the light emitting element solvent 100 and the thickener 500' is performed through the heat treatment process under the low pressure environment, the light emitting element solvent 100 and the thickener 500' remaining as foreign matter in the subsequent process can be completely removed. In addition, in the process of removing the light emitting element solvent 100 and the thickener 500', the change of the initial alignment state of the light emitting element 30 caused by the attraction force caused by the flow of the fluid or the attraction force between the thickener 500' and the light emitting element 30 can be prevented or reduced. For example, in the display device 10, the alignment degree of the light emitting element 30 can be improved.

[0235] Subsequently, a plurality of insulating layers and contact electrodes may be formed on the light emitting element 30 and the electrodes (21 and 22) to manufacture the display device 10. Through the above process, the display device 10 including the light emitting element 30 may be manufactured. The display device 10 may be manufactured using the light emitting element ink 1000 including the thickener 500'. In the display device 10, a uniform number of light emitting elements 30 may be arranged per unit area with high alignment, and product reliability may be improved.

[0236] In some embodiments, during the manufacturing process of the display device 10 , a process of applying light may be further performed to further improve the alignment of the light emitting element 30 .

[0237] Fig.18 is a cross-sectional view illustrating effective actions in a process of manufacturing a display device according to another embodiment.

[0238] refer to Fig.18 , in the process of manufacturing the display device 10, in the effective action of forming the electric field EL on the electrodes (21 and 22), ultraviolet light UV may be applied to the light emitting element 30 ejected on the target substrate SUB. The light emitting element 30 may have a dipole moment, and when the ultraviolet light UV is applied to the light emitting element 30, the light emitting element 30 may react with the ultraviolet light UV to have a larger dipole moment. The light emitting element 30 having a large dipole moment may be aligned so that one end thereof faces a set or predetermined direction in response to the electric field EL formed on the electrodes (21 and 22). At the same time, at least one end of the light emitting element 30 may be on the first electrode 21 or the second electrode 22. For example, each of the light emitting elements 30 may have a first end on the first electrode 21 and a second end on the second electrode 22.

[0239] In the effective action of placing the light emitting element 30 on the electrodes (21 and 22), while applying the ultraviolet light UV when the electric field EL is formed, the first end of the light emitting element 30 can be aligned in a set or predetermined direction as the electrophoretic reactivity of the light emitting element 30 increases. Therefore, the light emitting element 30 can be arranged on the electrodes (21 and 22) with a high degree of alignment, and the product reliability of the display device 10 can be further improved.

[0240] The light-emitting element ink according to the embodiment may contain a volatile thickener to have different viscosities in the storage state and in the printing state. In the storage state of the light-emitting element ink, the viscosity of the solution is high, so that the precipitation of the light-emitting element can be prevented or reduced. In the printing state of the light-emitting element ink, the viscosity of the solution is low, so that the nozzle is not clogged, and therefore, the ink can be easily discharged.

[0241] In the method for manufacturing a display device according to the embodiment, the display device is manufactured using the light-emitting element ink, so that the printing process can be performed in a state where the light-emitting element is dispersed in the ink, and a uniform number of light-emitting elements can be arranged per unit area with high alignment. In addition, by heat treatment under a low-pressure environment, the light-emitting element solvent and thickener that remain as foreign matter in the subsequent process can be completely removed. Therefore, a display device with improved product reliability can be manufactured.

[0242] In summarizing the detailed description, it will be appreciated by those skilled in the art that many changes and modifications may be made to the disclosed embodiments without departing substantially from the principles of the present disclosure. Therefore, the disclosed embodiments of the present disclosure are used in a general and descriptive sense only and not for the purpose of limitation.

Claims

1. A method for manufacturing a display device, include: preparing a light-emitting element ink including a light-emitting element solvent, a plurality of light-emitting elements, and a thickener, and preparing a target substrate including a first electrode and a second electrode; jetting the light emitting element ink onto the target substrate; forming an electric field on the target substrate while applying ultraviolet light to place the light-emitting element on the first electrode and the second electrode; as well as heat-treating the light-emitting element ink in a low-pressure environment to remove the light-emitting element solvent and the thickener, The compound of the thickener of the light emitting element ink contains a functional group capable of forming a hydrogen bond with a compound of the light emitting element solvent and / or another compound of the thickener, and includes a compound represented by the following Chemical Formula 1: Chemical formula 1 Wherein, in Chemical Formula 1, each R 1 is independently a substituted or unsubstituted alkylene group having 6 to 8 carbon atoms, a substituted or unsubstituted alkenylene group having 6 to 8 carbon atoms, or a substituted or unsubstituted alkynylene group having 6 to 8 carbon atoms, and each R 2 is independently an alkyl group having 3 to 6 carbon atoms, wherein the light emitting element is contained in the light emitting element ink in an amount of 0.01 parts by weight to 1 part by weight relative to 100 parts by weight of the light emitting element ink, and The thickener is contained in the light emitting element ink in an amount of 100 parts by weight to 500 parts by weight relative to 100 parts by weight of the light emitting element. In the preparation of the light emitting element ink, the light emitting element ink has a viscosity of 30 cP to 300 cP measured at 25° C., In the ejecting of the light emitting element ink, the light emitting element ink has a viscosity of 5 cP to 15 cP measured at 25°C.

2. The method according to claim 1, The compound of the thickener is represented by any one selected from Chemical Formula 2 to Chemical Formula 6: Chemical formula 2 Chemical formula 3 Chemical formula 4 Chemical formula 5 Chemical formula 6 in, In chemical formula 4, R 3 Yes*-(CH 2 CH 2 O) x CH 3 , x is an integer from 7 to 112, and *- is a bond to the oxygen atom.

3. The method according to claim 1, in, In the preparation of the light emitting element ink, the compound of the thickener forms an intermolecular hydrogen bond together with the compound of the light emitting element solvent and the other compound of the thickener to form a network structure.

4. The method according to claim 1, Among them in 10 -4 The removing of the light emitting element solvent and the thickener is performed at a pressure of Torr to 1 Torr and a temperature of 25°C to 150°C.

5. The method according to claim 1, in, In the placement of the light emitting element, a first end of the light emitting element is on the first electrode, and a second end of the light emitting element is on the second electrode.

6. The method according to claim 1, Each of the light emitting elements includes a first semiconductor layer, a second semiconductor layer, an active layer between the first semiconductor layer and the second semiconductor layer, and an insulating film surrounding at least an outer surface of the active layer.

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