Light-emitting element solvent, photodegradable thickener, light-emitting element ink, and method for manufacturing display device

Abstract

Provided are a light-emitting element solvent, a photodegradable thickener, a light-emitting element ink containing the light-emitting element solvent and the photodegradable thickener, and a method for manufacturing a display device. The method includes the steps of: spraying a light-emitting element ink containing a first element solvent and a light-emitting element dispersed in the first element solvent onto a target substrate having a first electrode and a second electrode formed thereon; forming a second element solvent in which at least some bonds of the first element solvent are decomposed by irradiating the first element solvent with light, and mounting the light-emitting element on the first electrode and the second electrode; and removing the second element solvent.

Description

Technical Field

[0001] The present disclosure relates to a light-emitting element solvent, a photodegradable thickener, a light-emitting element ink, and a method for manufacturing a display device. Background Art

[0002] The importance of display devices has increased with the development of multimedia. Accordingly, various types of display devices, such as organic light emitting display (OLED) devices and liquid crystal display (LCD) devices, are being used.

[0003] A display panel such as an OLED panel or an LCD panel is a device included in a display device to display an image. In such a display panel, a light-emitting element may be provided as a light-emitting display panel, and examples of light-emitting diodes (LEDs) include organic LEDs using organic materials as fluorescent materials and inorganic LEDs using inorganic materials as fluorescent materials.

[0004] Inorganic LEDs, which use inorganic semiconductors as fluorescent materials, are durable even in high-temperature environments and have higher efficiency in blue light than organic LEDs. In the manufacturing process, which has been cited as a limitation of existing inorganic LED components, a transfer method using dielectrophoresis (DEP) has been developed. Consequently, research continues into inorganic LEDs with higher durability and efficiency than organic LEDs.

[0005] Display devices including inorganic LEDs can be manufactured using an inkjet printing process, where small light-emitting elements are dispersed in ink and then sprayed onto electrodes. Each light-emitting element can include a semiconductor layer and can therefore be made of a material with a high specific gravity. The viscosity of the ink can determine the speed at which the light-emitting element settles and the likelihood of ejection through the nozzle.

[0006] For example, when the ink viscosity is low, the ink can be ejected smoothly through the nozzle, but the sedimentation rate of the light-emitting elements dispersed in the ink may be high. On the other hand, when the ink viscosity is high, the sedimentation rate of the light-emitting elements may slow down, but they may not be ejected through the nozzle. In addition, the solvent other than the light-emitting elements must be removed from the ink sprayed onto the electrode. However, when the ink viscosity is high, the solvent cannot be removed smoothly. Summary of the Invention

[0007] [Technical Issues]

[0008] Aspects of the present disclosure provide a light-emitting element solvent including a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with light, and a light-emitting element ink including the light-emitting element solvent.

[0009] Aspects of the present disclosure also provide a photodegradable thickener in which the molecular chains decompose upon irradiation with light.

[0010] Aspects of the present disclosure also provide a method for manufacturing a display device using a light-emitting element ink including the light-emitting element solvent and a light-emitting element dispersed in the light-emitting element solvent.

[0011] Aspects of the present disclosure also provide a light-emitting element ink whose viscosity is controlled by the photodegradable thickener and a light-emitting element contained therein, and a method of manufacturing a display device using the light-emitting element ink.

[0012] It should be noted that aspects of the present disclosure are not limited thereto, and other aspects not mentioned herein will be apparent to those skilled in the art from the following description.

[0013] [Technical solution]

[0014] According to an embodiment of the present disclosure, a method for manufacturing a display device includes: spraying a light-emitting element ink containing a first element solvent and a light-emitting element dispersed in the first element solvent on a target substrate having a first electrode and a second electrode formed thereon; forming a second element solvent in which at least some bonds of the first element solvent are decomposed by irradiating light to the first element solvent, and mounting the light-emitting element on the first electrode and the second electrode; and removing the second element solvent.

[0015] The first element solvent may include a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with light, and a first functional group and a second functional group bonded to the photodegradable functional group and represented by the following Chemical Formula 1, and the first element solvent may be at least one of the compounds represented by the following Chemical Formulas 2 to 5:

[0016] [Chemical Formula 1]

[0017]

[0018] wherein n is an integer from 1 to 5, the sum of the n value of the first functional group and the n value of the second functional group is 2 to 6, and R5 is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group, and

[0019] [Chemical Formula 2]

[0020]

[0021] [Chemical Formula 3]

[0022]

[0023] [Chemical Formula 4]

[0024]

[0025] [Chemical Formula 5]

[0026]

[0027] wherein R1 and R2 are represented by Chemical Formula 1, the sum of the value of n in Chemical Formula 1 of R1 and the value of n in Chemical Formula 1 of R2 is 2 to 6, and each of R3 and R4 is independently C1-C 10 Alkyl groups, C2-C 10 Alkenyl groups, C2-C 10 Alkynyl group, C1-C 10 Alkyl ether groups and C2-C 10 Any of the alkenyl ether groups.

[0028] In the forming of the second element solvent, at least some bonds of the photodegradable functional group may be decomposed by the irradiated light to form at least one photodegradable fragment, and the second element solvent may contain the photodegradable fragment.

[0029] The photodegradable fragment may be bonded to at least one of the first functional group and the second functional group.

[0030] The molecular weight of the second component solvent may be 50% or less than the molecular weight of the first component solvent.

[0031] The first element solvent may have a viscosity of 7 cp to 15 cp, and the second element solvent may have a viscosity of 5 cp or less.

[0032] The mounting of the light emitting element may include forming an electric field on the first electrode and the second electrode, and aligning an orientation direction of the light emitting element by the electric field.

[0033] The light emitting element may extend in one direction, and an acute angle formed by the direction in which the light emitting element extends and a direction perpendicular to a direction in which the first and second electrodes extend may be 88 degrees to 90 degrees.

[0034] According to an embodiment of the present disclosure, a light-emitting element solvent for dispersing semiconductor crystals includes: a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with light; and different first and second functional groups bonded to the photodegradable functional group, and the light-emitting element solvent is represented by the following Formula 1, wherein the chemical bond of the photodegradable functional group is decomposed when irradiated with the light to form at least one photodegradable fragment:

[0035] [Formula 1]

[0036] X1-P-X2,

[0037] wherein P is a photodegradable functional group, X1 is a first functional group, and X2 is a second functional group.

[0038] The first functional group and the second functional group may be represented by the above Chemical Formula 1, and the light-emitting element solvent may be any one of the compounds represented by the above Chemical Formulas 2 to 5.

[0039] The light-emitting element solvent may be a compound represented by the following Chemical Formula 6:

[0040] [Chemical Formula 6]

[0041]

[0042] The light-emitting element solvent may form a first element solvent represented by Formula 1 above, wherein the first element solvent may form a second element solvent containing the photodegradable fragment when irradiated with the light.

[0043] The photodegradable fragment may be bonded to at least one of the first functional group and the second functional group.

[0044] The molecular weight of the second component solvent may be 50% or less than the molecular weight of the first component solvent.

[0045] The first element solvent may have a viscosity of 7 cp to 15 cp, and the second element solvent may have a viscosity of 5 cp or less.

[0046] According to an embodiment of the present disclosure, a light-emitting element ink includes: a light-emitting element including a semiconductor crystal and an insulating film surrounding the peripheral surface of the semiconductor crystal; and a light-emitting element solvent in which one or more light-emitting elements are dispersed, wherein the light-emitting element solvent includes: a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with light; and a first functional group and a second functional group bonded to the photodegradable functional group and represented by the above Chemical Formula 1, and the light-emitting element solvent is any one of the compounds represented by the above Chemical Formulas 2 to 5.

[0047] The light-emitting element solvent may be a compound represented by Chemical Formula 6 above.

[0048] The chemical bond of the photodegradable functional group of the light-emitting element solvent may be decomposed by the light to form at least one photodegradable fragment, and the photodegradable fragment may be bonded to at least one of the first functional group and the second functional group.

[0049] Since the chemical bonds of the photodegradable functional groups are decomposed by the irradiated light, the viscosity of the light-emitting element solvent can be reduced.

[0050] The semiconductor crystal may include a first semiconductor layer doped with a first conductivity type, a second semiconductor layer doped with a second conductivity type having a different polarity from the first conductivity type, and an active layer formed between the first semiconductor layer and the second semiconductor layer.

[0051] According to an embodiment of the present disclosure, a method for manufacturing a display device includes: preparing a light-emitting element ink including a solvent and a plurality of light-emitting elements and a photodegradable thickener dispersed in the solvent, ejecting the light-emitting element ink onto a target substrate on which a first electrode and a second electrode are formed, and irradiating light to the light-emitting element ink and mounting the light-emitting elements on the first electrode and the second electrode.

[0052] Each of the photodegradable thickeners may include a third functional group including a functional group capable of forming a hydrogen bond and a photodegradable functional group bonded to the third functional group and wherein the bond is decomposed when irradiated with light, and is represented by any one of the following Formulas 2 to 5:

[0053] [Formula 2]

[0054]

[0055] [Formula 3]

[0056]

[0057] [Formula 4]

[0058]

[0059] [Formula 5]

[0060]

[0061] Wherein "HP1" and "HP2" are the third functional group, "HP1" is any one of a secondary amine group (-NH-), an acylamino group (-CONH-), a urea group (-NHCONH-) and a carbamate group (-NHCOO-), "HP2" is a hydroxyl group (-OH) or a primary amine group (-NH2), "CP" is a photodegradable functional group, "R6" is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group and a C2-C5 alkenyl ether group, R7 is any one of an acryloyl group, a methacryloyl group, an ester group and a carbonate group, m is an integer from 1 to 3, and l is an integer from 10 to 100.

[0062] Each of the photodegradable thickeners may be represented by any one of the following Chemical Formulas 7 to 11:

[0063] [Chemical Formula 7]

[0064]

[0065] [Chemical Formula 8]

[0066]

[0067] [Chemical Formula 9]

[0068]

[0069] [Chemical Formula 10]

[0070]

[0071] [Chemical Formula 11]

[0072]

[0073] wherein l is an integer from 10 to 100.

[0074] In the preparation of the light-emitting element ink, the photodegradable thickener can form a network structure because the third functional group forms an intermolecular hydrogen bond.

[0075] The light emitting element ink may have a viscosity of 30 cP to 70 cP when no shear stress is applied.

[0076] In the ejection of the light emitting element ink, the hydrogen bond of the third functional group in each of the photodegradable thickeners may be decomposed.

[0077] The light emitting element ink may have a viscosity of 5 cP to 15 cP when shear stress is applied.

[0078] When irradiated with the light, each of the photodegradable thickeners may form a plurality of fragment molecules because the photodegradable functional groups are decomposed.

[0079] The mounting of the light emitting element may include forming an electric field on the first electrode and the second electrode, aligning an orientation direction of the light emitting element by the electric field, and removing the solvent and the fragment molecules.

[0080] The removal of the solvent and the fragment molecules may be performed through a heat treatment process at 200°C to 400°C.

[0081] The light emitting element may extend in one direction, and an acute angle formed by the direction in which the light emitting element extends and the direction in which the first electrode and the second electrode extend may be 88 degrees to 90 degrees.

[0082] According to an embodiment of the present disclosure, a light-emitting element ink includes: a solvent; light-emitting elements dispersed in the solvent and each including a plurality of semiconductor layers and an insulating film partially surrounding the outer surface of the semiconductor layer; and a photodegradable thickener dispersed in the solvent, wherein each of the photodegradable thickeners includes a third functional group including a functional group capable of forming a hydrogen bond and a photodegradable functional group bonded to the third functional group and wherein the bond is decomposed when irradiated with light, and the photodegradable thickener is represented by any one of Formulas 2 to 5 above.

[0083] The photodegradable functional group may include any one of a cyclobutyl group, a maleimide dimer, an acrylate dimer, and a carbonyl group.

[0084] Each of the photodegradable thickeners is represented by any one of Chemical Formula 7 to Chemical Formula 11 above.

[0085] When no shear stress is applied, the photodegradable thickener may form a network structure because the third functional group forms an intermolecular hydrogen bond.

[0086] The light emitting element ink may have a viscosity of 30 cP to 70 cP when no shear stress is applied.

[0087] When shear stress is applied, the intermolecular hydrogen bond of the third functional group of the photodegradable thickener may be decomposed.

[0088] The light emitting element ink may have a viscosity of 5 cP to 15 cP when shear stress is applied.

[0089] The semiconductor layer of the light emitting element may include a first semiconductor layer; a second semiconductor layer; and an active layer disposed between the first semiconductor layer and the second semiconductor layer, and the insulating film may surround at least an outer surface of the active layer.

[0090] According to an embodiment of the present disclosure, a photodegradable thickener includes: a third functional group including a functional group capable of forming a hydrogen bond; and a photodegradable functional group bonded to the third functional group and wherein the bond is decomposed when irradiated with light, the photodegradable thickener being represented by any one of Formulae 2 to 5 above.

[0091] Details of other embodiments are included in the detailed description and accompanying drawings.

[0092] [Beneficial Effects]

[0093] The light-emitting element solvent according to the embodiment includes a photodegradable functional group and a first functional group and a second functional group bonded to the photodegradable functional group. Because the chemical bonds of the photodegradable functional group are partially decomposed by irradiated light, the viscosity can be reduced. Therefore, the light-emitting element contained in the light-emitting element ink can be dispersed in the light-emitting element solvent having a reduced viscosity.

[0094] In addition, in the method for manufacturing a display device according to the embodiment, the process of aligning the light-emitting elements is performed using a light-emitting element solvent with reduced viscosity in which the light-emitting elements are dispersed. Therefore, a display device with improved alignment of light-emitting elements provided on electrodes can be manufactured.

[0095] The photodegradable thickener according to the embodiment may include a functional group that can form hydrogen bonds and a photodegradable functional group in which the bonds are decomposed when irradiated with light. When there is no flow, the photodegradable thickener may have a high viscosity due to the hydrogen bonds formed by the polymerizable groups. However, when shear stress is applied to the photodegradable thickener, the photodegradable thickener may have a low viscosity without forming hydrogen bonds.

[0096] The light-emitting element ink according to the embodiment may include a solvent, a light-emitting element and a photodegradable thickener. Therefore, when there is no flow of ink, the solvent may have a high viscosity due to the photodegradable thickener, and the light-emitting element may remain dispersed for a long time. On the other hand, when the ink is ejected through the nozzle, shear stress is applied to the solvent and the photodegradable thickener. Therefore, the viscosity of the solvent can be reduced, and the light-emitting elements can be ejected from the nozzle in a state in which they are dispersed in the solvent. In addition, when light is irradiated to the light-emitting element ink ejected on the target substrate, the photodegradable functional group of the photodegradable thickener can be decomposed, and because the viscosity of the light-emitting element ink is reduced, the light-emitting element ink can be easily removed at a certain temperature.

[0097] Therefore, according to the embodiment, a display device including a light emitting element can be manufactured through an inkjet printing method by using a light emitting element ink including a light emitting element and a photodegradable thickener.

[0098] Effects according to the embodiment are not limited to the above-exemplified contents, and more various effects are included in the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 is a plan view of a display device according to an embodiment;

[0100] Figure 2 is a plan view of a pixel of a display device according to the embodiment;

[0101] Figure 3 It is along Figure 2 Cross-sectional views taken along line IIIa-IIIa', line IIIb-IIIb', and line IIIc-IIIc';

[0102] Figure 4 is a cross-sectional view of a portion of a display device according to another embodiment;

[0103] Figure 5 is a schematic diagram of a light-emitting element according to the embodiment;

[0104] Figure 6 and Figure 7 is a schematic diagram of a light-emitting element according to another embodiment;

[0105] Figure 8 is a schematic diagram of a light-emitting element ink according to the embodiment;

[0106] Figure 9 and Figure 10 yes Figure 8 an enlarged view of part A;

[0107] Figure 11 is a flowchart illustrating a method for manufacturing a display device according to the embodiment;

[0108] Figure 12 and Figure 13 is a cross-sectional view illustrating a portion of a method for manufacturing a display device according to the embodiment;

[0109] Figures 14 to 16 is a schematic diagram illustrating a process in which a light-emitting element dispersed in an element solvent is placed on an electrode according to the embodiment;

[0110] Figure 17 is a plan view illustrating a state in which a solvent of an element has been removed according to an embodiment;

[0111] Figure 18 is a cross-sectional view illustrating a state in which a solvent of an element has been removed according to an embodiment;

[0112] Figure 19 is a schematic diagram illustrating an operation of forming a second element solvent according to an embodiment;

[0113] Figures 20 to 22 is a schematic diagram illustrating a process in which a light-emitting element dispersed in an element solvent is placed on an electrode according to the embodiment;

[0114] Figure 23 is a cross-sectional view illustrating an operation of removing a solvent of a second member according to an embodiment;

[0115] Figure 24 is a plan view illustrating alignment of a light emitting element according to the embodiment;

[0116] Figure 25 is a schematic diagram of a light-emitting element ink according to the embodiment;

[0117] Figure 26 is a schematic diagram illustrating the arrangement of a photodegradable thickener in a state in which shear stress is not applied to the light emitting element ink according to the embodiment;

[0118] Figure 27 is a schematic diagram illustrating the arrangement of a photodegradable thickener in a state in which shear stress has been applied to the light emitting element ink according to the embodiment;

[0119] Figure 28 is a schematic diagram illustrating a photodegradable thickener when light is irradiated to a light emitting element ink according to the embodiment;

[0120] Figure 29 is a flowchart illustrating a method for manufacturing a display device according to the embodiment;

[0121] Figures 30 to 32 is a cross-sectional view illustrating an operation in a process of manufacturing a display device according to the embodiment;

[0122] Figures 33 to 35 is a schematic diagram illustrating a process of placing a light-emitting element on an electrode during a process of manufacturing a display device;

[0123] Figures 36 to 38 is a schematic diagram illustrating a process of placing a light emitting element on an electrode during a process of manufacturing a display device according to the embodiment; and

[0124] Figure 39is a cross-sectional view illustrating a portion of a method for manufacturing a display device according to the embodiment. DETAILED DESCRIPTION

[0125] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. However, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.

[0126] It will also be understood that when a layer is referred to as being 'on' another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like components throughout the specification.

[0127] It should be understood that although the terms "first," "second," etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first element discussed below may be referred to as the second element without departing from the teachings of the present invention. Similarly, the second element may also be referred to as the first element.

[0128] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0129] Figure 1 is a plan view of a display device according to the embodiment.

[0130] refer to Figure 1 The display device 10 displays a moving image or a still image. The display device 10 may refer to any electronic device that provides a display screen. Examples of the display device 10 may include a television, a notebook computer, a monitor, a billboard, the Internet of Things (IoT), a mobile phone, a smartphone, a tablet personal computer (PC), an electronic watch, a smartwatch, a watch phone, a head-mounted display, a mobile communication terminal, an electronic notebook, an electronic book, a portable multimedia player (PMP), a navigation device, a game console, a digital camera, and / or a video camera, all of which provide a display screen.

[0131] The display device 10 includes a display panel that provides a display screen. Examples of display panels include inorganic light-emitting diode display panels, organic light-emitting display panels, quantum dot light-emitting display panels, plasma display panels, and field emission display panels. Hereinafter, a case where an inorganic light-emitting diode display panel is used as an example of a display panel will be described, but the present disclosure is not limited to this case, and other display panels may also be applied as long as the same technical principles are applicable.

[0132] The shape of the display device 10 can be modified in various ways. For example, the display device 10 can have various shapes such as a horizontally long rectangle, a vertically long rectangle, a square, a quadrilateral with rounded corners (vertices), other polygons, and a circle. The shape of the display area DPA of the display device 10 can also be similar to the overall shape of the display device 10. Figure 1 , the display device 10 and the display area DPA having a horizontally long rectangular shape are exemplified.

[0133] The display device 10 may include a display area DPA and a non-display area NDA. The display area DPA may be an area where a screen can be displayed, and the non-display area NDA may be an area where a screen is not displayed. The display area DPA may also be referred to as an active area, and the non-display area NDA may also be referred to as a non-active area. The display area DPA may generally occupy the center of the display device 10.

[0134] The display area DPA may include a plurality of pixels PX. The pixels PX may be arranged in a matrix direction. Each of the pixels PX may be rectangular or square in a plan view. However, the present disclosure is not limited thereto, and each of the pixels PX may also have a rhombus planar shape with each side tilted relative to one direction. The pixels PX may be alternately arranged in a stripe or tile type. In addition, each of the pixels PX may include one or more light-emitting elements 30 that emit light of a specific wavelength band to display a specific color.

[0135] The non-display area NDA may be disposed around the display area DPA. The non-display area NDA may completely or partially surround the display area DPA. The display area DPA may be rectangular, and the non-display area NDA may be disposed adjacent to four sides of the display area DPA. The non-display area NDA may form a barrier for the display device 10. Wiring or a circuit driver included in the display device 10 may be disposed in each non-display area NDA, or an external device may be installed.

[0136] Figure 2 is a plan view of a pixel of a display device according to the embodiment. Figure 3 It is along Figure 2 Cross-sectional views taken along line IIIa-IIIa', line IIIb-IIIb' and line IIIc-IIIc'.

[0137] refer to Figure 2, each of the pixels PX may include a plurality of sub-pixels PXn (where 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. 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 the sub-pixels PXn may also emit light of the same color. In addition, although in Figure 2 One pixel PX includes three sub-pixels PXn, but the present disclosure is not limited thereto, and the pixel PX may also include more sub-pixels PXn.

[0138] Each sub-pixel PXn of the display device 10 may include an area defined as an emission area EMA. The first sub-pixel PX1 may include a first emission area EMA1, the second sub-pixel PX2 may include a second emission area EMA2, and the third sub-pixel PX3 may include a third emission area EMA3. The emission area EMA may be defined as an area in which the light emitting element 30 included in the display device 10 is arranged to emit light of a specific wavelength band. Each light emitting element 30 may include an active layer 36 (see Figure 5 ), and the active layer 36 can emit light of a specific wavelength band without directionality. The light emitted from the active layer 36 of each light emitting element 30 can be irradiated toward both sides of the light emitting element 30. The emission area EMA can include a region in which the light emitting element 30 is disposed, and a region adjacent to the light emitting element 30 and toward which light emitted from the light emitting element 30 is output.

[0139] However, the present disclosure is not limited thereto, and the emission area EMA may also include an area from which light emitted from the light emitting element 30 is output after being reflected or refracted by other components. A plurality of light emitting elements 30 may be provided in each sub-pixel PXn, and the area in which the light emitting element 30 is provided and an area adjacent to the area may form the emission area EMA.

[0140] Although not illustrated in the drawings, each sub-pixel PXn of the display device 10 may include a non-emission region defined as a region different from the emission region EMA. The non-emission region may be a region in which the light emitting element 30 is not disposed and from which no light is output because light emitted from the light emitting element 30 does not reach the region.

[0141] Figure 3 For example, only Figure 2 1 is a cross-section of the first subpixel PX1, but the same illustration may apply to other pixels PX or subpixels PXn. Figure 3A cross section spanning one end portion and the other end portion of the light emitting element 30 provided in the first sub-pixel PX1 is illustrated.

[0142] Combine Figure 2 refer to Figure 3 The display device 10 may include a first substrate 11, and a circuit element layer and a display element layer provided on the first substrate 11. A semiconductor layer, a plurality of conductive layers, and a plurality of insulating layers may be provided on the first substrate 11, and may constitute the circuit element layer and the display element layer. The conductive layer may include a first gate conductive layer, a second gate conductive layer, a first data conductive layer, and a second data conductive layer provided under the first planarization layer 19 to form the circuit element layer, and may include electrodes 21 and 22 and a contact electrode 26 provided on the first planarization layer 19 to form the display element layer. The insulating layer may include a buffer layer 12, a first gate insulating layer 13, a first protective layer 15, a first interlayer insulating layer 17, a second interlayer insulating layer 18, a first planarization layer 19, a first insulating layer 51, a second insulating layer 52, a third insulating layer 53, and a fourth insulating layer 54.

[0143] Specifically, the first substrate 11 may be an insulating substrate. The first substrate 11 may be made of an insulating material such as glass, quartz, or polymer resin. In addition, the first substrate 11 may be a rigid substrate, but may also be a flexible substrate that can be bent, folded, or rolled.

[0144] Light-blocking layers BML1 and BML2 may be disposed on the first substrate 11. The light-blocking layers BML1 and BML2 may include a first light-blocking layer BML1 and a second light-blocking layer BML2. The first light-blocking layer BML1 and the second light-blocking layer BML2 are overlapped by at least the first active material layer DT_ACT of the drive transistor DT and the second active material layer ST_ACT of the switch transistor ST, respectively. The light-blocking layers BML1 and BML2 may include a light-blocking material to prevent light from entering the first active material layer DT_ACT and the second active material layer ST_ACT. For example, the first light-blocking layer BML1 and the second light-blocking layer BML2 may be made of an opaque metal material that blocks the transmission of light. However, the present disclosure is not limited thereto. In some cases, the light-blocking layers BML1 and BML2 may be omitted or may be formed only below the first active material layer DT_ACT.

[0145] The buffer layer 12 may be provided on the entire surface of the first substrate 11 and on the light blocking layers BML1 and BML2. The buffer layer 12 may be formed on the first substrate 11 to protect the transistors DT and ST of each pixel PX from moisture introduced through the first substrate 11 (which is susceptible to moisture permeation) and may perform a surface planarization function. The buffer layer 12 may be composed of a plurality of inorganic layers stacked alternately. For example, the buffer layer 12 may be a multilayer in which inorganic layers including at least one of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON) are alternately stacked.

[0146] The semiconductor layer is disposed on the buffer layer 12. The semiconductor layer may include a first active material layer DT_ACT of the driving transistor DT and a second active material layer ST_ACT of the switching transistor ST. These layers may be partially overlapped by gate electrodes DT_G and ST_G of a first gate conductive layer to be described later.

[0147] In the embodiment, the semiconductor layer may include polycrystalline silicon, single crystal silicon, an oxide semiconductor, or the like. Polycrystalline silicon may be formed by crystallizing amorphous silicon. When the semiconductor layer includes polycrystalline silicon, the first active material layer DT_ACT may include a first doped region DT_ACTa, a second doped region DT_ACTb, and a first channel region DT_ACTc. The first channel region DT_ACTc may be disposed between the first doped region DT_ACTa and the second doped region DT_ACTb. The second active material layer ST_ACT may include a third doped region ST_ACTa, a fourth doped region ST_ACTb, and a second channel region ST_ACTc. The second channel region ST_ACTc may be disposed between the third doped region ST_ACTa and the fourth doped region ST_ACTb. The first doped region DT_ACTa, the second doped region DT_ACTb, the third doped region ST_ACTa, and the fourth doped region ST_ACTb may be regions of the first active material layer DT_ACT and the second active material layer ST_ACT doped with impurities.

[0148] In another embodiment, the first active material layer DT_ACT and the second active material layer ST_ACT may include an oxide semiconductor. In this case, the doped regions of the first active material layer DT_ACT and the second active material layer ST_ACT may be conductive regions. The oxide semiconductor may be an oxide semiconductor containing indium (In). In some embodiments, the oxide semiconductor may be indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium oxide (IGO), indium zinc tin oxide (IZTO), indium gallium tin oxide (IGTO), or indium gallium zinc tin oxide (IGZTO). However, the present disclosure is not limited thereto.

[0149] The first gate insulating layer 13 is provided on the semiconductor layer and the buffer layer 12. The first gate insulating layer 13 may be provided on the buffer layer 12 and the semiconductor layer. The first gate insulating layer 13 may function as a gate insulating film for each of the driving transistor DT and the switching transistor ST. The first gate insulating layer 13 may be an inorganic layer containing an inorganic material (e.g., silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiON)), or may have a structure in which the above materials are stacked.

[0150] A first gate conductive layer is disposed on the first gate insulating layer 13. The first gate conductive layer may include a first gate electrode DT_G of the drive transistor DT and a second gate electrode ST_G of the switch transistor ST. The first gate electrode DT_G may overlap the first channel region DT_ACTc of the first active material layer DT_ACT in the thickness direction, and the second gate electrode ST_G may overlap the second channel region ST_ACTc of the second active material layer ST_ACT in the thickness direction.

[0151] The first gate conductive layer can be, but is not limited to, a single layer or multiple layers made of any one or more of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu) and alloys thereof.

[0152] The first protective layer 15 is provided on the first gate conductive layer. The first protective layer 15 may cover the first gate conductive layer to protect the first gate conductive layer. The first protective layer 15 may be an inorganic layer containing an inorganic material (e.g., silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiON)), or may have a structure in which the above materials are stacked.

[0153] The second gate conductive layer is disposed on the first protective layer 15. The second gate conductive layer may include a first capacitor electrode CE1 of a storage capacitor, at least a portion of which overlaps the first gate electrode DT_G in the thickness direction. The first capacitor electrode CE1 may overlap the first gate electrode DT_G in the thickness direction, with the first protective layer 15 interposed therebetween, and a storage capacitor may be formed therebetween. The second gate conductive layer may be, but is not limited to, a single layer or multiple layers made of any one or more of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and alloys thereof.

[0154] A first interlayer insulating layer 17 is provided on the second gate conductive layer. The first interlayer insulating layer 17 may function as an insulating film between the second gate conductive layer and other layers provided on the second gate conductive layer. The first interlayer insulating layer 17 may be an inorganic layer containing an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiON), or may have a structure in which the above materials are stacked.

[0155] The first data conductive layer is disposed on the first interlayer insulating layer 17. The first gate conductive layer may include first and second source / drain electrodes DT_SD1 and DT_SD2 of the driving transistor DT and first and second source / drain electrodes ST_SD1 and ST_SD2 of the switching transistor ST.

[0156] The first source / drain electrode DT_SD1 and the second source / drain electrode DT_SD2 of the driving transistor DT may respectively contact the first doped region DT_ACTa and the second doped region DT_ACTb of the first active material layer DT_ACT through contact holes penetrating the first interlayer insulating layer 17, the first protective layer 15, and the first gate insulating layer 13. The first source / drain electrode ST_SD1 and the second source / drain electrode ST_SD2 of the switching transistor ST may respectively contact the third doped region ST_ACTa and the fourth doped region ST_ACTb of the second active material layer ST_ACT through contact holes penetrating the first interlayer insulating layer 17 and the first gate insulating layer 13. Furthermore, the first source / drain electrode DT_SD1 of the driving transistor DT and the first source / drain electrode ST_SD1 of the switching transistor ST may respectively be electrically connected to the first light-blocking layer BML1 and the second light-blocking layer BML2 through other contact holes. When any one of the first source / drain electrode DT_SD1 or ST_SD1 and the second source / drain electrode DT_SD2 or ST_SD2 of each of the drive transistor DT and the switch transistor ST is a source electrode, the other electrode may be a drain electrode. However, the present disclosure is not limited thereto, and when any one of the first source / drain electrode DT_SD1 or ST_SD1 and the second source / drain electrode DT_SD2 or ST_SD2 is a drain electrode, the other electrode may be a source electrode.

[0157] The first data conducting layer may be, but is not limited to, a single layer or multiple layers made of any one or more of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and alloys thereof.

[0158] The second interlayer insulating layer 18 may be provided on the first data conducting layer. The second interlayer insulating layer 18 may be provided on the entire surface of the first interlayer insulating layer 17 to cover and protect the first data conducting layer. The second interlayer insulating layer 18 may be an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiON), or may have a structure in which the above materials are stacked.

[0159] The second data conducting layer is disposed on the second interlayer insulating layer 18. 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 driving transistor DT may be applied to the first voltage line VL1, and a low potential voltage (or a second power supply voltage VSS) supplied to the second electrode 22 may be applied to the second voltage line VL2. As will be described later, the first power supply voltage may be applied to the first electrode 21 through the driving transistor DT, and the second power supply voltage may be applied to the second electrode 22 connected to the second voltage line VL2 through a contact hole. During the process of manufacturing the display device 10, an alignment signal required to align the light-emitting element 30 may be transmitted to the second voltage line VL2.

[0160] The first conductive pattern CDP can be electrically connected to the first source / drain electrode DT_SD1 of the drive transistor DT through a contact hole formed in the second interlayer insulating layer 18. The first conductive pattern CDP can also contact the first electrode 21, which will be described later. The drive transistor DT transmits the first power supply voltage received from the first voltage line VL1 to the first electrode 21 through the first conductive pattern CDP. Although the second data conductive layer includes one second voltage line VL2 and one first voltage line VL1 in the drawings, the present disclosure is not limited thereto. The second data conductive layer may also include more first voltage lines VL1 and more second voltage lines VL2.

[0161] The second data conducting layer may be, but is not limited to, a single layer or multiple layers made of any one or more of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), and alloys thereof.

[0162] The first planarization layer 19 is disposed on the second data conducting layer. The first planarization layer 19 may include an organic insulating material such as polyimide (PI) and perform a surface planarization function.

[0163] Inner blocks 41 and 42, electrodes 21 and 22, outer blocks 45, contact electrodes 26, and light emitting elements 30 are disposed on the first planarization layer 19. In addition, insulating layers 51 to 54 may be further disposed on the first planarization layer 19.

[0164] The inner blocks 41 and 42 may be directly disposed on the first planarization layer 19. The inner blocks 41 and 42 may include a first inner block 41 and a second inner block 42 disposed adjacent to the center of each sub-pixel PXn.

[0165] The first internal block 41 and the second internal block 42 may be spaced apart in the first direction DR1 to face each other. The internal blocks 41 and 42 spaced apart to face each other may form a region in which the light emitting element 30 is disposed therebetween. In addition, the first internal block 41 and the second internal block 42 may extend in the second direction DR2, but may terminate at a position spaced apart from a boundary between sub-pixels PXn so as not to extend to another sub-pixel PXn adjacent in the second direction DR2. Therefore, the first internal block 41 and the second internal block 42 may be disposed in each sub-pixel PXn to form a linear pattern on the entire surface of the display device 10. Although Figure 3 4. Although only one first inner block 41 and one second inner block 42 are illustrated in FIG, the present disclosure is not limited thereto. Depending on the number of electrodes 21 and 22 to be described later, more inner blocks 41 and 42 may be further provided.

[0166] At least a portion of each of the first inner block 41 and the second inner block 42 may protrude from the upper surface of the first planarization layer 19. The protruding portion of each of the first inner block 41 and the second inner block 42 may have an inclined side surface, and the light emitted from the light emitting element 30 may travel toward the inclined side surfaces of the inner blocks 41 and 42. As will be described later, the electrodes 21 and 22 provided on the inner blocks 41 and 42 may include a material having a high reflectivity, and the light emitted from the light emitting element 30 may be reflected by the electrodes 21 and 22 provided on the side surfaces of the inner blocks 41 and 42 to travel upward on the first planarization layer 19. That is, the inner blocks 41 and 42 may provide an area in which the light emitting element 30 is provided, while functioning as a reflective barrier that reflects the light emitted from the light emitting element 30 in an upward direction. In the embodiment, the inner blocks 41 and 42 may include an organic insulating material such as polyimide (PI), but the present disclosure is not limited thereto.

[0167] Electrodes 21 and 22 are provided on the inner blocks 41 and 42 and the first planarization layer 19. Electrodes 21 and 22 can be electrically connected to the light-emitting element 30, and a predetermined voltage can be applied to the electrodes 21 and 22 so that the light-emitting element 30 can emit light of a specific wavelength band. In addition, at least a portion of 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.

[0168] The electrodes 21 and 22 may include a first electrode 21 disposed on the first inner block 41 and a second electrode 22 disposed on the second inner block 42 .

[0169] Each of the first and second electrodes 21 and 22 may include an electrode trunk portion 21S or 22S extending in a first direction DR1 and at least one electrode branch portion 21B or 22B extending and branching from the electrode trunk portion 21S or 22S in a second direction DR2 intersecting the first direction DR1 .

[0170] The first electrode 21 may include a first electrode trunk portion 21S extending in the first direction DR1 and at least one first electrode branch portion 21B branched from the first electrode trunk portion 21S and extending in the second direction DR2 .

[0171] The first electrode trunk portion 21S may have two ends that terminate between sub-pixels PXn and are spaced apart from the ends of adjacent first electrode trunk portions 21S, but may be located on substantially the same straight line as the first electrode trunk portions 21S of adjacent pixels in the same row (e.g., adjacent in the first direction DR1). Since the two ends of the first electrode trunk portions 21S, respectively disposed in the sub-pixels PXn, are spaced apart from each other, different electrical signals can be transmitted to each first electrode branch portion 21B, and each first electrode branch portion 21B can be driven separately. The first electrode 21 may contact the first conductive pattern CDP through a first contact hole CT1 penetrating the first planarization layer 19, and thus may be electrically connected to the first source / drain electrode DT_SD1 of the drive transistor DT.

[0172] The first electrode branch portion 21B may branch from at least a portion of the first electrode trunk portion 21S and extend in the second direction DR2 to terminate at a position spaced apart from the second electrode trunk portion 22S facing the first electrode trunk portion 21S.

[0173] The second electrode 22 may include a second electrode trunk portion 22S extending in the first direction DR1 and spaced apart from the first electrode trunk portion 21S in the second direction DR2 to face the first electrode trunk portion 21S, and second electrode branches 22B branched from the second electrode trunk portion 22S and extending in the second direction DR2.

[0174] The second electrode trunk 22S may extend beyond the boundaries with other adjacent sub-pixels PXn in the first direction DR1. The second electrode trunk 22S intersecting with multiple sub-pixels PXn may be connected to the surrounding portion of the display area DPA or the portion extending in the direction of the non-display area NDA. The second electrode 22 may contact the second voltage line VL2 through a second contact hole CT2 penetrating the first planarization layer 19. As illustrated in the accompanying drawings, the second electrodes 22 of adjacent sub-pixels PXn in the first direction DR1 may be connected to one second electrode trunk 22S and thus electrically connected to the second voltage line VL2 through the second contact hole CT2. However, the present disclosure is not limited thereto. In some cases, the second contact hole CT2 may also be formed in each sub-pixel PXn.

[0175] The second electrode branch portion 22B may be spaced apart from the first electrode branch portion 21B to face the first electrode branch portion 21B, and may terminate at a position spaced apart from the first electrode trunk portion 21S. The second electrode branch portion 22B may be connected to the second electrode trunk portion 22S, and an end portion in the extension direction may be spaced apart from the first electrode trunk portion 21S in the subpixel PXn.

[0176] Although two first electrode branches 21B and one second electrode branch 22B are provided in each sub-pixel PXn in the accompanying drawings, the present disclosure is not limited thereto. In some embodiments, more first electrode branches 21B and more second electrode branches 22B may be provided in each sub-pixel PXn. In addition, the first electrode 21 and the second electrode 22 provided in each sub-pixel PXn do not have to extend in one direction and may be provided in various structures. For example, the first electrode 21 and the second electrode 22 may be partially bent or folded, or either of the first electrode 21 and the second electrode 22 may surround the other electrode. The structure or shape in which the first electrode 21 and the second electrode 22 are provided is not particularly limited, as long as the first electrode 21 and the second electrode 22 are at least partially spaced apart to face each other, so that the area in which the light-emitting element 30 is to be provided can be formed between the first electrode 21 and the second electrode 22.

[0177] The first electrode 21 and the second electrode 22 may be disposed on the first inner block 41 and the second inner block 42, respectively, and may be spaced apart to face each other. The respective electrode branches 21B and 22B of the first electrode 21 and the second electrode 22 may be disposed on the first inner block 41 and the second inner block 42, but at least a portion of each of them may be disposed directly on the first planarization layer 19. At least one end of each of the light-emitting elements 30 disposed between the first inner block 41 and the second inner block 42 may be electrically connected to the first electrode 21 and the second electrode 22.

[0178] Each of the electrodes 21 and 22 may 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), or indium tin zinc oxide (ITZO), but the present disclosure is not limited thereto. In some embodiments, each of the electrodes 21 and 22 may include a conductive material having a high reflectivity. For example, each of the electrodes 21 and 22 may include a metal such as silver (Ag), copper (Cu), or aluminum (Al) as a material having a high reflectivity. In this case, each of the electrodes 21 and 22 may reflect incident light upward on each sub-pixel PXn.

[0179] In addition, each of the electrodes 21 and 22 may have a structure in which a transparent conductive material and a metal layer having high reflectivity are each stacked in one or more layers, or may be formed as a single layer containing them. In the embodiment, each of the electrodes 21 and 22 may have a stacked structure of ITO / Ag / ITO / IZO, or may be an alloy containing aluminum (Al), nickel (Ni), lanthanum (La), etc., but the present disclosure is not limited thereto.

[0180] The electrodes 21 and 22 may be electrically connected to the light emitting element 30, and a predetermined voltage may be applied to the electrodes 21 and 22 so that the light emitting element 30 may emit light. For example, the electrodes 21 and 22 may be electrically connected to the light emitting element 30 via the contact electrode 26 described later, and the received electrical signal may be transmitted to the light emitting element 30 via the contact electrode 26.

[0181] In the embodiment, the first electrode 21 may be a pixel electrode individually used for each sub-pixel PXn, and the second electrode 22 may be a common electrode commonly connected along each sub-pixel PXn. Either the first electrode 21 or the second electrode 22 may be an anode of the light-emitting element 30, and the other may be a cathode of the light-emitting element 30. However, the present disclosure is not limited thereto, and the opposite may also be true.

[0182] In addition, each of the electrodes 21 and 22 can be used to form an electric field in the sub-pixel PXn in order to align the light-emitting element 30. The light-emitting element 30 can be placed between the first electrode 21 and the second electrode 22 by forming an electric field between the first electrode 21 and the second electrode 22 by transmitting an alignment signal to the first electrode 21 and the second electrode 22. The light-emitting element 30 can be ejected onto the first electrode 21 and the second electrode 22 by an inkjet process in a state in which the light-emitting element 30 is dispersed in light-emitting element ink, and can be aligned between the first electrode 21 and the second electrode 22 by applying a dielectrophoretic force to the light-emitting element 30 by transmitting an alignment signal between the first electrode 21 and the second electrode 22.

[0183] The first insulating layer 51 is disposed on the first planarization layer 19 and the first and second electrodes 21 and 22. The first insulating layer 51 partially covers the first and second electrodes 21 and 22. The first insulating layer 51 may cover most of the upper surface of each of the first and second electrodes 21 and 22, but may expose a portion of each of the first and second electrodes 21 and 22. The first insulating layer 51 may partially expose the upper surface of each of the first and second electrodes 21 and 22, for example, the upper surface of the first electrode branch 21B disposed on the first inner block 41 and the upper surface of the second electrode branch 22B disposed on the second inner block 42. The first insulating layer 51 may be formed on substantially the entire surface of the first planarization layer 19, but may include openings that partially expose the first and second electrodes 21 and 22.

[0184] In the embodiment, the first insulating layer 51 may be stepped so that a portion of the upper surface of the first insulating layer 51 is recessed between the first electrode 21 and the second electrode 22. In some embodiments, the first insulating layer 51 may include an inorganic insulating material, and a portion of the upper surface of the first insulating layer 51 provided to cover the first electrode 21 and the second electrode 22 may be recessed due to a step formed by a member provided under the first insulating layer 51. The light-emitting element 30 provided on the first insulating layer 51 between the first electrode 21 and the second electrode 22 may form a blank space with the recessed upper surface of the first insulating layer 51. The light-emitting element 30 may be partially spaced apart from the upper surface of the first insulating layer 51, and the blank space may be filled with a material for forming the second insulating layer 52 to be described later. However, the present disclosure is not limited thereto. The first insulating layer 51 may also form a flat upper surface so that the light-emitting element 30 may be provided on the flat upper surface.

[0185] The first insulating layer 51 can protect the first electrode 21 and the second electrode 22 while insulating them from each other. In addition, the first insulating layer 51 can prevent the light emitting element 30 provided on the first insulating layer 51 from directly contacting other components and being damaged. However, the shape and structure of the first insulating layer 51 are not limited to the above examples.

[0186] The outer block 45 may be disposed on the first insulating layer 51. In some embodiments, the outer block 45 disposed on the first insulating layer 51 may surround the region where the light emitting element 30 is disposed and the region where the inner blocks 41 and 42 and the electrodes 21 and 22 are disposed, and may be disposed at each boundary between the sub-pixels PXn. The outer block 45 may extend in the first direction DR1 and the second direction DR2 to form a grid pattern over the entire display area DPA.

[0187] According to the embodiment, the height of the outer block 45 may be greater than the height of each of the inner blocks 41 and 42. Unlike the inner blocks 41 and 42, the outer block 45 can separate adjacent sub-pixels PXn while preventing the light-emitting element ink from overflowing to the adjacent sub-pixels PXn during the inkjet printing process for placing the light-emitting elements 30 during the process of manufacturing the display device 10 as will be described later. The outer block 45 can separate the light-emitting element ink in which different light-emitting elements 30 are dispersed for different sub-pixels PXn so that the light-emitting element inks do not mix with each other. Like the inner blocks 41 and 42, the outer block 45 may include polyimide (PI), but the present disclosure is not limited thereto.

[0188] The light emitting element 30 may be arranged between the electrodes 21 and 22. For example, the light emitting element 30 may be arranged between the electrode branches 21B and 22B. The light emitting elements 30 may be spaced apart from each other and aligned substantially parallel to each other. The gaps between the light emitting elements 30 are not particularly limited. In some cases, a plurality of light emitting elements 30 may be arranged adjacent to each other to form a cluster, and a plurality of other light emitting elements 30 may be arranged at regular intervals to form a cluster or may be arranged with an uneven density. In addition, in an embodiment, the light emitting element 30 may extend in one direction, and the direction in which the electrodes 21 and 22 extend and the direction in which the light emitting element 30 extends may be substantially perpendicular to each other. However, the present disclosure is not limited thereto, and the light emitting element 30 may also extend in a direction that is not perpendicular to the direction in which the electrodes 21 and 22 extend but is tilted.

[0189] The light-emitting element 30 according to the embodiment may include an active layer 36 including different materials to emit light of different wavelength bands. The display device 10 may include light-emitting elements 30 that emit light of different wavelength bands. For example, each light-emitting element 30 of the first subpixel PX1 may include an active layer 36 that emits light of a first color whose central wavelength band is a first wavelength, each light-emitting element 30 of the second subpixel PX2 may include an active layer 36 that emits light of a second color whose central wavelength band is a second wavelength, and each light-emitting element 30 of the third subpixel PX3 may include an active layer 36 that emits light of a third color whose central wavelength band is a third wavelength.

[0190] Thus, light of the first color, light of the second color, and light of the third color can be output by the first subpixel PX1, the second subpixel PX2, and the third subpixel PX3, respectively. In some embodiments, the light of the first color can be blue light having a central wavelength band of 450 to 495 nm, the light of the second color can be green light having a central wavelength band of 495 to 570 nm, and the light of the third color can be red light having a central wavelength band of 620 to 752 nm. However, the present disclosure is not limited thereto. In some cases, the first subpixel PX1, the second subpixel PX2, and the third subpixel PX3 can include the same type of light-emitting element 30 to emit light of substantially the same color.

[0191] The light-emitting element 30 may be disposed on the first insulating layer 51 between the inner blocks 41 and 42 or between the electrodes 21 and 22. For example, the light-emitting element 30 may be disposed on the first insulating layer 51 disposed between the inner blocks 41 and 42. At the same time, a portion of each light-emitting element 30 may overlap each of the electrodes 21 and 22 in the thickness direction. One end of each light-emitting element 30 may be disposed on the first electrode 21 so as to overlap the first electrode 21 in the thickness direction, and the other end may be disposed on the second electrode 22 so as to overlap the second electrode 22 in the thickness direction. However, the present disclosure is not limited thereto. Although not illustrated in the drawings, at least some of the light-emitting elements 30 disposed in each subpixel PXn may be disposed in a region different from the region formed between the inner blocks 41 and 42, for example, may be disposed in a region different from the region between the electrode branches 21B and 22B, or may be disposed between the inner blocks 41 and 42 and the outer block 45.

[0192] Each of the light-emitting elements 30 may include a plurality of layers arranged in a direction perpendicular to the upper surface of the first substrate 11 or the first planarization layer 19. According to the embodiment, each of the light-emitting elements 30 may extend in one direction and have a structure in which a plurality of semiconductor layers are sequentially arranged along the direction. The direction in which the light-emitting elements 30 of the display device 10 extend may be parallel to the first planarization layer 19, and the semiconductor layers included in each of the light-emitting elements 30 may be sequentially arranged in a direction parallel to the upper surface of the first planarization layer 19. However, the present disclosure is not limited thereto. In some cases, when the light-emitting element 30 has a different structure, the layer may be arranged in a direction perpendicular to the first planarization layer 19.

[0193] In addition, an end portion of each light emitting element 30 may contact the first contact electrode 26a, and the other end portion may contact the second contact electrode 26b. Figure 5) may not be formed on the end surface of each light-emitting element 30 in the extending direction of each light-emitting element 30, thereby exposing some of the semiconductor layer. Therefore, the exposed semiconductor layer can contact the first contact electrode 26a and the second contact electrode 26b described later. However, the present disclosure is not limited to this. In some cases, at least a portion of the insulating film 38 of each light-emitting element 30 can be removed to partially expose the side surfaces of both ends of the semiconductor layer.

[0194] The second insulating layer 52 may be provided on a portion of each light-emitting element 30, the portion of each light-emitting element 30 being provided between the first electrode 21 and the second electrode 22. The second insulating layer 52 may partially cover the outer surface of each light-emitting element 30. The portion of the second insulating layer 52 provided on the light-emitting element 30 may extend in the second direction DR2 between the first electrode 21 and the second electrode 22 in a plan view. For example, the second insulating layer 52 may form a stripe or island pattern in each sub-pixel PXn.

[0195] The second insulating layer 52 may be provided on the light-emitting elements 30, but may expose one end and the other end of each light-emitting element 30. The exposed end of each light-emitting element 30 may contact the contact electrode 26, which will be described later. This shape of the second insulating layer 52 can be formed by performing a patterning process using the material forming the second insulating layer 52 using a conventional mask process. The mask used to form the second insulating layer 52 may have a width less than the length of each light-emitting element 30, and the material forming the second insulating layer 52 may be patterned to expose both ends of each light-emitting element 30. However, the present disclosure is not limited thereto.

[0196] The second insulating layer 52 can protect the light-emitting element 30 while fixing the light-emitting element 30 during the process of manufacturing the display device 10. In addition, in the embodiment, a portion of the material of the second insulating layer 52 can be provided between the lower surface of the light-emitting element 30 and the first insulating layer 51. As described above, the second insulating layer 52 can be formed to fill the space between the first insulating layer 51 and the light-emitting element 30 formed during the process of manufacturing the display device 10. Therefore, the second insulating layer 52 can cover the outer surface of each light-emitting element 30 to protect the light-emitting element 30, while fixing the light-emitting element 30 during the process of manufacturing the display device 10.

[0197] The contact electrode 26 is provided on the first electrode 21, the second electrode 22, and the second insulating layer 52. In addition, the third insulating layer 53 may be provided on any one of the contact electrodes 26.

[0198] The contact electrode 26 may extend in one direction. The contact electrode 26 may contact the light emitting element 30 and the electrodes 21 and 22 , respectively, and the light emitting element 30 may receive electrical signals from the first electrode 21 and the second electrode 22 through the contact electrode 26 .

[0199] The contact electrode 26 may include a first contact electrode 26a and a second contact electrode 26b. The first contact electrode 26a and the second contact electrode 26b may be disposed on the first electrode 21 and the second electrode 22, respectively. Each of the first contact electrode 26a and the second contact electrode 26b may extend in the second direction DR2. The first contact electrode 26a and the second contact electrode 26b may be spaced apart from each other in the first direction DR1 and may form a stripe pattern in the emission area EMA of each sub-pixel PXn.

[0200] In some embodiments, the widths of the first contact electrode 26a and the second contact electrode 26b measured in one direction can be equal to or greater than the widths of the first electrode 21 and the second electrode 22 measured in that direction, respectively. The first contact electrode 26a and the second contact electrode 26b can contact one end and the other end of each light-emitting element 30, respectively, and cover both side surfaces of the first electrode 21 and the second electrode 22. In addition, at least a portion of each of the first contact electrode 26a and the second contact electrode 26b can be disposed on the first insulating layer 51. In addition, at least a portion of each of the first contact electrode 26a and the second contact electrode 26b can be disposed on the second insulating layer 52. The first contact electrode 26a can be disposed directly on the second insulating layer 52, and the second contact electrode 26b can be disposed directly on the third insulating layer 53, which is disposed on the first contact electrode 26a, and can overlap the second insulating layer 52. However, the present disclosure is not limited to this, and the third insulating layer 53 can also be omitted, so that the second contact electrode 26b is disposed directly on the second insulating layer 52.

[0201] As described above, the upper surfaces of the first and second electrodes 21 and 22 may be partially exposed, and the first and second contact electrodes 26a and 26b may contact the exposed upper surfaces of the first and second electrodes 21 and 22. For example, the first contact electrode 26a may contact a portion of the first electrode 21 located on the first inner block 41, and the second contact electrode 26b may contact a portion of the second electrode 22 located on the second inner block 42. However, the present disclosure is not limited thereto, and in some cases, the first and second contact electrodes 26a and 26b may have a smaller width than the first and second electrodes 21 and 22 to cover only the exposed portions of the upper surfaces of the first and second electrodes 21 and 22.

[0202] According to the embodiment, the semiconductor layer may be exposed on both end surfaces of each light emitting element 30 in the extension direction, and the first contact electrode 26a and the second contact electrode 26b may contact each light emitting element 30 at the end surface where the semiconductor layer is exposed. However, the present disclosure is not limited thereto. In some cases, the semiconductor layer may be exposed on the side surfaces of both ends of each light emitting element 30, and the contact electrodes 26 may respectively contact the exposed semiconductor layers. One end of each light emitting element 30 may be electrically connected to the first electrode 21 via the first contact electrode 26a, and the other end may be electrically connected to the second electrode 22 via the second contact electrode 26b.

[0203] Although two first contact electrodes 26a and one second contact electrode 26b are provided in one sub-pixel PXn in the drawings, the present disclosure is not limited thereto. The number of first contact electrodes 26a and second contact electrodes 26b may vary depending on the number of first electrode branches 21B and second electrode branches 22B provided in each sub-pixel PXn.

[0204] The contact electrode 26 may include a conductive material such as ITO, IZO, ITZO, or aluminum (Al). For example, the contact electrode 26 may include a transparent conductive material, and light emitted from the light-emitting element 30 may pass through the contact electrode 26 and travel toward the electrodes 21 and 22. Each of the electrodes 21 and 22 may include a material having a high reflectivity, and the electrodes 21 and 22 provided on the inclined side surfaces of the inner blocks 41 and 42 may reflect incident light upward on the first substrate 11. However, the present disclosure is not limited thereto.

[0205] The third insulating layer 53 is provided on the first contact electrode 26a. The third insulating layer 53 can electrically insulate the first contact electrode 26a and the second contact electrode 26b from each other. The third insulating layer 53 can cover the first contact electrode 26a, but may not be provided on the other end of each light-emitting element so that the light-emitting element 30 can contact the second contact electrode 26b. The third insulating layer 53 can be provided on the upper surface of the second insulating layer 52 to partially contact the first contact electrode 26a and the second insulating layer 52. The side surface of the third insulating layer 53 in the direction in which the second electrode 22 is provided can be aligned with the side surface of the second insulating layer 52. In addition, the third insulating layer 53 can be provided in a non-emitting region, for example, on the first insulating layer 51 provided on the first planarization layer 19. However, the present disclosure is not limited thereto.

[0206] The fourth insulating layer 54 may be provided on the entire surface of the first substrate 11. The fourth insulating layer 54 may play a role in protecting members provided on the first substrate 11 from the external environment.

[0207] Each of the first insulating layer 51, the second insulating layer 52, the third insulating layer 53, and the fourth insulating layer 54 described above may include an inorganic insulating material or an organic insulating material. In an embodiment, the first insulating layer 51, the second insulating layer 52, the third insulating layer 53, and the fourth insulating layer 54 may include an inorganic insulating material, such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (Al2O3), or aluminum nitride (AlN). Alternatively, they may include an organic insulating material, such as an acrylic resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimide resin, an unsaturated polyester resin, a polyphenylene resin, a polyphenylene sulfide resin, a benzocyclobutene, a cardo resin, a siloxane resin, a silsesquioxane resin, polymethyl methacrylate, polycarbonate, or a polymethyl methacrylate-polycarbonate synthetic resin. However, the present disclosure is not limited thereto.

[0208] Figure 4 is a cross-sectional view of a portion of a display device according to another embodiment.

[0209] refer to Figure 4 In the display device 10 according to the embodiment, the third insulating layer 53 may be omitted. The second contact electrode 26b may be directly provided on the second insulating layer 52, and the first contact electrode 26a and the second contact electrode 26b may be spaced apart from each other on the second insulating layer 52. Figure 4 Implementation plan and Figure 3 The embodiment is the same as that of FIG. 1 , but omits the third insulating layer 53. Therefore, redundant description will be omitted below.

[0210] The light emitting element 30 may be a light emitting diode. Specifically, the light emitting element 30 may be an inorganic light emitting diode having a micrometer or nanometer size and made of an inorganic material. When an electric field is formed in a specific direction between two electrodes facing each other, the inorganic light emitting diode may be aligned between the two electrodes where polarity is formed.

[0211] Figure 5 is a schematic diagram of a light-emitting element according to the embodiment.

[0212] refer to Figure 5 , the light emitting element 30 according to the embodiment may extend in one direction. The light emitting element 30 may be shaped as a rod, a wire, a tube, etc. In the embodiment, the light emitting element 30 may be shaped as a cylinder or a rod. However, the shape of the light emitting element 30 is not limited thereto, and the light emitting element 30 may also have various shapes, including polygonal prisms (e.g., cubes, rectangular parallelepipeds, or hexagonal prisms) and shapes extending in one direction and having a partially inclined outer surface.

[0213] The light-emitting element 30 may include a semiconductor layer doped with impurities of any conductivity type (e.g., p-type or n-type). The semiconductor layer may receive an electrical signal from an external power source and emit light of a specific wavelength band. The plurality of semiconductors included in the light-emitting element 30 may be sequentially arranged or stacked in one direction.

[0214] The light emitting element 30 may include a first semiconductor layer 31, a second semiconductor layer 32, an active layer 36, an electrode layer 37, and an insulating film 38. In order to visually show each element of the light emitting element 30, the insulating film 38 is formed on the surface of the light emitting element 30. Figure 5 3. The insulating film 38 is illustrated as being partially removed to expose the semiconductor layers 31, 32 and the active layer 36. However, as will be described later, the insulating film 38 may be provided to surround the outer surfaces of the semiconductor layers 31, 32 and the active layer 36.

[0215] Specifically, the first semiconductor layer 31 may be an n-type semiconductor. In an example, when the light emitting element 30 emits light in a blue wavelength band, the first semiconductor layer 31 may include a layer having Al x Ga y In 1-x-y The semiconductor material of the chemical formula N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) may be, for example, any one or more of n-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The first semiconductor layer 31 may be doped with an n-type dopant, and the n-type dopant may be, for example, Si, Ge, Se, or Sn. In an embodiment, the first semiconductor layer 31 may be n-GaN doped with n-type Si. The length of the first semiconductor layer 31 may be, but is not limited to, 1.5 μm to 5 μm.

[0216] The second semiconductor layer 32 is provided on the active layer 36 to be described later. The second semiconductor layer 32 may be a p-type semiconductor. In an example, when the light emitting element 30 emits light in a blue or green wavelength band, the second semiconductor layer 32 may include a substrate having Al x Ga y In 1-x-y The semiconductor material of the chemical formula of N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) may be, for example, any one or more of p-type doped AlGaInN, GaN, AlGaN, InGaN, AlN, and InN. The second semiconductor layer 32 may be doped with a p-type dopant, and the p-type dopant may be, for example, Mg, Zn, Ca, or Ba. In an embodiment, the second semiconductor layer 32 may be p-GaN doped with p-type Mg. The length of the second semiconductor layer 32 may be, but is not limited to, 0.05 μm to 0.10 μm.

[0217] Although each of the first semiconductor layer 31 and the second semiconductor layer 32 is composed of one layer in the drawings, the present disclosure is not limited thereto. According to some embodiments, each of the first semiconductor layer 31 and the second semiconductor layer 32 may include more layers, for example, a cladding layer or a tensile strain barrier lowering (TSBR) layer may be further included depending on the material of the active layer 36.

[0218] The active layer 36 is disposed between the first semiconductor layer 31 and the second semiconductor layer 32. The active layer 36 may include a material having a single quantum well structure or a multiple quantum well structure. When the active layer 36 includes a material having a multiple quantum well structure, it may have a structure in which multiple quantum layers and multiple well layers are alternately stacked. According to the electrical signal received through the first semiconductor layer 31 and the second semiconductor layer 32, the active layer 36 may emit light by recombination of electron-hole pairs. For example, when the active layer 36 emits light in the blue wavelength band, it may include a material such as AlGaN or AlGaInN. Specifically, when the active 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 or AlGaInN, and the well layers may include materials such as GaN or AlInN. In an embodiment, the active layer 36 may include AlGaInN as quantum layers and AlInN as well layers to emit blue light whose central wavelength band is 450nm to 495nm.

[0219] However, the present disclosure is not limited thereto, and the active layer 36 may also have a structure in which semiconductor materials having large band gap energy and semiconductor materials having small band gap energy are alternately stacked, or may contain different Group 3 to Group 5 semiconductor materials depending on the wavelength band of the emitted light. The light emitted from the active layer 36 is not limited to light in the blue wavelength band. In some cases, the active layer 36 may emit light in the red or green wavelength band. The length of the active layer 36 may be, but is not limited to, 0.05 μm to 0.10 μm.

[0220] The light emitted from the active layer 36 may be irradiated not only to the outer surface in the longitudinal direction of the light emitting element 30 but also to both side surfaces. The direction of the light emitted from the active layer 36 is not limited to one direction.

[0221] The electrode layer 37 may be an ohmic contact electrode. However, the present disclosure is not limited thereto, and the electrode layer 37 may also be a Schottky contact electrode. The light emitting element 30 may include at least one electrode layer 37. Figure 5In the embodiment of the present invention, 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 more electrode layers 37, or may omit the electrode layer 37. Even when the light emitting element 30 includes a different number of electrode layers 37 or further includes other structures, the following description of the light emitting element 30 may also apply.

[0222] 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 and / or contact electrode. The electrode layer 37 may include a conductive metal. For example, the electrode layer 37 may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). In addition, the electrode layer 37 may include a semiconductor material doped with n-type or p-type. The electrode layer 37 may include the same material or different materials. The length of the electrode layer 37 may be, but is not limited to, 0.05 μm to 0.10 μm.

[0223] The insulating film 38 surrounds the outer surfaces of the semiconductor layer and the electrode layer described above. In the embodiment, the insulating film 38 may surround at least the outer surface of the active layer 36 and extend in the direction in which the light-emitting element 30 extends. The insulating film 38 may protect the above components. For example, the insulating film 38 may surround the side surfaces of the above components, but may expose both ends of the light-emitting element 30 in the longitudinal direction.

[0224] In the drawings, the insulating film 38 extends in the longitudinal direction of the light emitting element 30 to cover the side surface from the first semiconductor layer 31 to the side surface of the electrode layer 37. However, the present disclosure is not limited thereto, and the insulating film 38 may cover only some of the semiconductor layers and the outer surface of the active layer 36, or may cover only a portion of the outer surface of the electrode layer 37 to partially expose the outer surface of each electrode layer 37. Alternatively, the cross-section of the upper surface of the insulating film 38 in the region adjacent to at least one end of the light emitting element 30 may be circular.

[0225] The thickness of the insulating film 38 may be, but is not limited to, 10 nm to 1.0 μm. The thickness of the insulating film 38 may preferably be approximately 40 nm.

[0226] 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), or aluminum oxide (Al2O3). Therefore, the insulating film 38 can prevent electrical short circuits that may occur when the active layer 36 directly contacts the electrode through which the electrical signal is transmitted to the light-emitting element 30. Furthermore, the insulating film 38 can prevent a decrease in luminous efficiency by protecting the outer surface of the light-emitting element 30 including the active layer 36.

[0227] In addition, in some embodiments, the outer surface of the insulating film 38 may be treated. When manufacturing the display device 10, a plurality of light-emitting elements 30 may be ejected onto an electrode in a state where the light-emitting elements 30 are dispersed in a predetermined light-emitting element ink, and then aligned. Here, the surface of the insulating film 38 may be treated to be hydrophobic or hydrophilic so that the light-emitting elements 30 remain separated from other adjacent light-emitting elements 30 in the light-emitting element ink and do not aggregate with them.

[0228] The length h of the light-emitting element 30 may be 1 μm to 10 μm or 2 μm to 6 μm, and may preferably be 3 μm to 5 μm. In addition, the diameter of the light-emitting element 30 may be 30 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 also have different diameters depending on the composition of the active layer 36. The diameter of the light-emitting element 30 may preferably be about 500 nm.

[0229] The shape and material of the light emitting element 30 are not limited to Figure 5 In some embodiments, light emitting element 30 can include more layers or can have a different shape.

[0230] Figure 6 and Figure 7 is a schematic diagram of a light-emitting element according to another embodiment.

[0231] First, refer to Figure 6 The light emitting element 30' according to the embodiment may further include a third semiconductor layer 33' disposed between the first semiconductor layer 31' and the active layer 36', and a fourth semiconductor layer 34' and a fifth semiconductor layer 35' disposed between the active layer 36' and the second semiconductor layer 32'. Figure 6 The light emitting element 30' is different from Figure 5 The embodiment is that a plurality of semiconductor layers 33', 34' and 35' and electrode layers 37a' and 37b' are further provided, and the active layer 36' contains other elements. Therefore, any redundant description will be omitted, and the differences will be mainly described below.

[0232] As described above, Figure 5 The light emitting element 30 can emit blue or green light because the active layer 36 contains nitrogen (N). Figure 6 The light-emitting element 30' can be a semiconductor in which each of the active layer 36' and other semiconductor layers contains at least phosphorus (P). That is, the light-emitting element 30' according to the embodiment can emit red light whose central wavelength band is 620nm to 750nm. However, the central wavelength band of red light is not limited to the above range and should be understood to include all wavelength ranges that can be regarded as red in the field to which the present disclosure belongs.

[0233] Specifically, the first semiconductor layer 31 ′ may be an n-type semiconductor layer and may include an In x Al y Ga 1-x-y The first semiconductor layer 31' 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 be any one or more of n-type doped InAlGaP, GaP, AlGaP, InGaP, AlP, and InP. In an embodiment, the first semiconductor layer 31' may be n-InAlGaP doped with n-type Si.

[0234] The second semiconductor layer 32 ′ may be a p-type semiconductor layer and may include In x Al y Ga 1-x-y The second semiconductor layer 32' may be a semiconductor material having a chemical formula of P (0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, the second semiconductor layer 32' may be any one or more of p-type doped InAlGaP, GaP, AlGaNP, InGaP, AlP, and InP. In an embodiment, the second semiconductor layer 32' may be p-GaP doped with p-type Mg.

[0235] The active layer 36' may be disposed between the first semiconductor layer 31' and the second semiconductor layer 32'. The active layer 36' may include a material having a single quantum well structure or a multiple quantum well structure to emit light in a specific wavelength band. When the active 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 AlGaP or AlInGaP, and the well layers may include materials such as GaP or AlInP. In an embodiment, the active layer 36' may include InAlGaP as a quantum layer and AlInP as a well layer to emit red light having a central wavelength band of 620nm to 750nm.

[0236] Figure 6The light emitting element 30' may include a cladding layer disposed adjacent to the active layer 36'. As illustrated in the drawings, the third semiconductor layer 33' and the fourth semiconductor layer 34' disposed above and below the active layer 36' and between the first semiconductor layer 31' and the second semiconductor layer 32' may be cladding layers.

[0237] The third semiconductor layer 33' may be disposed between the first semiconductor layer 31' and the active layer 36'. Like the first semiconductor layer 31', the third semiconductor layer 33' may be an n-type semiconductor. For example, the third semiconductor layer 33' may include an In x Al y Ga 1-x-y P (0≤x≤1, 0≤y≤1, 0≤x+y≤1). In the embodiment, the first semiconductor layer 31' may be n-InAlGaP, and the third semiconductor layer 33' may be n-AlInP. However, the present disclosure is not limited thereto.

[0238] The fourth semiconductor layer 34' may be disposed between the active 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. For example, the fourth semiconductor layer 34' may include a substrate having In x Al y Ga 1-x-y A semiconductor material having a chemical formula of P (0≤x≤1, 0≤y≤1, 0≤x+y≤1). In an embodiment, the second semiconductor layer 32 ′ may be p-GaP, and the fourth semiconductor layer 34 ′ may be p-AlInP.

[0239] The fifth semiconductor layer 35' may be disposed 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 doped semiconductor. In some embodiments, the fifth semiconductor layer 35' may reduce the difference in lattice constant between the fourth semiconductor layer 34' and the second semiconductor layer 32'. That is, the fifth semiconductor layer 35' may be a tensile strain barrier reduction (TSBR) layer. For example, the fifth semiconductor layer 35' may include, but is not limited to, p-GaInP, p-AlInP, or p-InAlGaP. In addition, the third semiconductor layer 33', the fourth semiconductor layer 34', and the fifth semiconductor layer 35' may have a length of, but is not limited to, 0.08 μm to 0.25 μm.

[0240] The first electrode layer 37a' and the second electrode layer 37b' may be provided on the first semiconductor layer 31' and the second semiconductor layer 32', respectively. The first electrode layer 37a' may be provided on the lower surface of the first semiconductor layer 31', and the second electrode layer 37b' may be provided 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 also be omitted. For example, in the light-emitting element 30', the first electrode layer 37a' may not be provided on the lower surface of the first semiconductor layer 31', and only one second electrode layer 37b' may be provided on the upper surface of the second semiconductor layer 32'.

[0241] Then, refer to Figure 7 , the light emitting element 30 ″ may extend in one direction but may have a partially inclined side surface. That is, the light emitting element 30 ″ according to the embodiment may have a partially conical shape.

[0242] In the light emitting element 30", a plurality of layers may not be stacked in one direction, but each layer may be formed to surround the outer surface of another layer. The light emitting element 30" may include a semiconductor core at least a portion of which extends in one direction and an insulating film 38" surrounding the semiconductor core. The semiconductor core may include a first semiconductor layer 31", an active layer 36", a second semiconductor layer 32" and an electrode layer 37".

[0243] The first semiconductor layer 31″ may extend in one direction and have two ends inclined toward the center. The first semiconductor layer 31″ may have a rod-shaped or cylindrical body and ends formed on and below the body, respectively, and having inclined side surfaces. The upper end of the body may have a steeper slope than the lower end thereof.

[0244] The active layer 36″ surrounds the outer surface of the main body of the first semiconductor layer 31″. The active layer 36″ may have a ring shape extending in one direction. The active layer 36″ may not be formed on the upper and lower ends of the first semiconductor layer 31″. However, the present disclosure is not limited thereto. The light emitted from the active layer 36″ may be irradiated not only to the two ends of the light emitting element 30″ in the longitudinal direction, but also to the two side surfaces in the longitudinal direction. Figure 7 The light emitting element 30" can emit more Figure 5 The light emitting element 30 emits a greater amount of light because its active layer 36 ″ has a larger area.

[0245] The second semiconductor layer 32″ surrounds the outer surface of the active layer 36″ and the upper end portion of the first semiconductor layer 31″. The second semiconductor layer 32″ may include a ring-shaped body extending in one direction and an upper end portion having an inclined side surface. That is, the second semiconductor layer 32″ may directly contact the parallel side surfaces of the active 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″.

[0246] The electrode layer 37 ″ surrounds the outer surface of the second semiconductor layer 32 ″. The shape of the electrode layer 37 ″ may be substantially the same as that of the second semiconductor layer 32 ″. The electrode layer 37 ″ may contact the entire outer surface of the second semiconductor layer 32 ″.

[0247] 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 not only the electrode layer 37", but also the lower end portion of the first semiconductor layer 31" and the exposed lower end portions of the active layer 36" and the second semiconductor layer 32".

[0248] As described above, the light emitting element 30 may be dispersed in the element solvent 100 (see Figure 8 ) is sprayed onto the electrodes 21 and 22 in a state in which an alignment signal is transmitted to the electrodes 21 and 22, and can be placed between the electrodes 21 and 22 by transmitting an alignment signal to the electrodes 21 and 22. In some embodiments, the light-emitting element 30 can be prepared in a state in which the light-emitting element 30 is dispersed in the element solvent 100, and can be sprayed on each electrode 21 or 22 by an inkjet printing process. Then, when the alignment signal is transmitted to each electrode 21 and 22, an electric field can be formed between them, and the light-emitting element 30 can be subjected to the dielectrophoretic force applied by the electric field. The light-emitting element 30 subjected to the dielectrophoretic force can be placed between the first electrode 21 and the second electrode 22 when its orientation direction and position are changed.

[0249] Figure 8 is a schematic diagram of a light-emitting element ink according to the embodiment.

[0250] refer to Figure 8 The light emitting element ink 1000 includes a light emitting element 30 and an element solvent 100. The light emitting element 30 may be the light emitting element described above. Figures 5 to 7 The light emitting element 30 is shown in the accompanying drawings. Figure 5 The light emitting element 30 may be prepared in a state where the light emitting element 30 is dispersed in the element solvent 100. The detailed description of the light emitting element 30 is the same as the above description.

[0251] The light-emitting elements 30 have a relatively large specific gravity because they contain semiconductor crystals. The element solvent 100 according to the embodiment may include a material with a high viscosity so that the light-emitting elements 30 can be dispersed therein. The light-emitting element ink 1000 can be sprayed on the electrodes 21 and 22 by an inkjet printing device, and the element solvent 100 may have a viscosity that can keep the light-emitting elements 30 dispersed for a certain period of time. In the embodiment, the viscosity of the element solvent 100 may be, but is not limited to, 7cp to 15cp. The element solvent 100 may include an organic solvent or an inorganic solvent, may be removed in a subsequent process as will be described later, and may include a material that does not damage the semiconductor crystals of the light-emitting element 30.

[0252] When the light-emitting element 30 is placed on the electrodes 21 and 22, the element solvent 100 in which the light-emitting element 30 is dispersed can be removed by heating or a subsequent treatment process. Here, the element solvent 100 can have a high viscosity so that the light-emitting element 30 with a relatively large specific gravity can remain dispersed. The element solvent 100 may include a compound with a relatively large molecular weight. Therefore, the element solvent 100 may not be completely removed, but may remain as foreign matter on the electrodes 21 and 22 or the light-emitting element 30. In addition, when the element solvent 100 has a viscosity at a certain level or higher, the dielectrophoretic force applied by the electric field may be insufficient. Therefore, the light-emitting element 30 may not be smoothly aligned on the electrodes 21 and 22, or the alignment state of the light-emitting element 30 may change during the process of removing the element solvent 100.

[0253] According to the embodiment, the element solvent 100 may include a photodegradable functional group 150 in which at least one chemical bond decomposes upon light irradiation. The molecular weight and viscosity of the element solvent 100 may vary depending on the state of the photodegradable functional group 150 or whether a bond is formed. That is, the element solvent 100 may form a first element solvent 101 having a high molecular weight and viscosity in a state in which the bond of the photodegradable functional group 150 is not decomposed, and may form a second element solvent 102 having a low molecular weight and viscosity when the bond of the photodegradable functional group 150 is decomposed.

[0254] Figure 9 and Figure 10 yes Figure 8 An enlarged view of part A of FIG.

[0255] Figure 9 The first element solvent 101 is illustrated as being formed when the chemical bond of the photodegradable functional group 150 of the element solvent 100 is not decomposed, and Figure 10 The second component solvent 102 formed when the chemical bonds of the photodegradable functional groups 150 are decomposed is illustrated.

[0256] In this specification, it is understood that "element solvent 100" refers to a solvent or a medium thereof in which the light-emitting element 30 can be dispersed, and "element solvent molecules 100'" refer to chemical molecules constituting the element solvent 100. As will be described later, the "element solvent 100" can form a "first element solvent 101" or a "second element solvent 102" depending on the state of the "element solvent molecules 100'", and it is understood that the first element solvent 101 is composed of the "first element solvent molecules 101'" and the second element solvent 102 is composed of the "second element solvent molecules 102'".

[0257] Right now, Figure 8 The element solvent 100 may be composed of Figure 9 The first element solvent molecules 101' constitute the first element solvent 101, and Figure 10 The second component solvent molecules 102' of the element solvent 100 can constitute the second component solvent 102. However, these terms may not necessarily be used separately. In some cases, the terms "component solvent 100" and "component solvent molecules 101'" can be used interchangeably and can have substantially the same meaning. The component solvent molecules 100' of the element solvent 100 will now be described in detail.

[0258] refer to Figure 9 and Figure 10 , the element solvent molecule 100 ′ may include a photodegradable functional group 150 , a first functional group 110 , and a second functional group 120 .

[0259] The first functional group 110 (X1) and the second functional group 120 (X2) may be functional groups having a molecular weight of a certain level or higher so that the light-emitting element 30 can be dispersed. The type or structure of the first functional group 110 and the second functional group 120 is not particularly limited, as long as the first functional group 110 and the second functional group 120 can disperse the light-emitting element 30 without reacting with them and can be removed in a subsequent process. For example, each of the first functional group 110 and the second functional group 120 may be, but is not limited to, a non-polar functional group having a carbon chain or a polar functional group containing an oxygen (O) or nitrogen (N) atom in the carbon chain.

[0260] In an embodiment, the first functional group 110 and the second functional group 120 may include functional groups having the same structure. The first functional group 110 and the second functional group 120 may have substantially the same molecular structure by including functional groups in which monomers of the same structure are repeatedly bonded. However, the present disclosure is not limited thereto, and the number of repetitions of the monomers of the first functional group 110 and the second functional group 120 may also be different, and in some cases may have opposite polarities. This will be described in detail later.

[0261] The photodegradable functional group 150 (P) may be bonded to the first functional group 110 and the second functional group 120, and at least one bond may be decomposed by irradiated light to form at least one photodegradable fragment. The photodegradable functional group 150 may include a first photodegradable functional group 151 in which the bond is not decomposed, and a second photodegradable functional group 152 which is a photodegradable fragment formed by decomposition of the chemical bond of the first photodegradable functional group 151. Figure 9 The first photodegradable functional group 151 is exemplified in Figure 10 , the second photodegradable functional group 152 is illustrated in FIG. When the first photodegradable functional group 151 absorbs irradiated light, some chemical bonds may be decomposed to form the second photodegradable functional group 152 .

[0262] The photodegradable functional group 150 can be constructed to have relatively weak bonds. In order to form an energetically stable structure by absorbing the energy of the irradiated light, some of the bonds in the photodegradable functional group 150 may be decomposed. Here, when the bonds are decomposed, the photodegradable functional group 150 can form photodegradable fragments with small molecular weight. That is, when the first photodegradable functional group 151 absorbs light, the bonds of the first photodegradable functional group 151 can be decomposed to form the second photodegradable functional group 152. Depending on the structure of the photodegradable functional group 150, the position of the decomposed bonds, etc., the first element solvent molecule 101' can form multiple second element solvent molecules 102' having the same structure. However, the present disclosure is not limited to this. In some cases, depending on the structure of the first element solvent molecule 101', second element solvent molecules 102' having different structures can be formed.

[0263] In the first element solvent molecule 101', the first functional group 110 and the second functional group 120 are contained in a single molecule. However, when the bond of the first photodegradable functional group 151 is decomposed, they can be respectively contained in different second element solvent molecules 102'. The first functional group 110 and the second functional group 120 bonded to the photodegradable functional group 150 can be bonded to opposite positions based on the bond of the photodegradable functional group 150. That is, the first functional group 110 and the second functional group 120 are respectively bonded to the second photodegradable functional group 152, wherein the bond has been decomposed to form different second element solvent molecules 102'. In an embodiment, the second element solvent molecule 102' containing the photodegradable fragment can include at least one of the first functional group 110 and the second functional group 120. However, the present disclosure is not limited to this.

[0264] When the first component solvent 101 is irradiated with light, it can form the second component solvent 102 having a low viscosity. In an embodiment, the first component solvent 101 can have a viscosity of 7 cp to 15 cp, and the second component solvent 102 can have a viscosity of 5 cp or less. That is, the first component solvent molecules 101 'can have a larger molecular weight than the second component solvent molecules 102'.

[0265] As described above, when manufacturing the display device 10, operations of ejecting the light-emitting element ink 1000, aligning the light-emitting elements 30 on the electrodes 21 and 22, and then removing the element solvent 100 can be performed. Here, if the element solvent 100 is a first element solvent 101 having a high viscosity due to the inclusion of the first element solvent molecules 101', when an electric field is formed in the light-emitting element ink 1000, a relatively weak dielectrophoretic force may be applied to the light-emitting elements 30. Therefore, the light-emitting elements 30 may not be accurately aligned on the electrodes 21 and 22. In addition, the first element solvent 101 may remain as foreign matter and not be completely removed when the element solvent 100 is removed.

[0266] According to the embodiment, the method for manufacturing the display device 10 includes forming the second element solvent 102 having low viscosity by irradiating light to the first element solvent 101. Since the element solvent 100 according to the embodiment includes the photodegradable functional group 150 in which the bond is decomposed by the irradiated light, its molecular weight and viscosity can be reduced by the light.

[0267] The first element solvent molecules 101' are partially decomposed by irradiating the element solvent 100 (i.e., the first element solvent 101 sprayed onto the electrodes 21 and 22) with light, thereby forming second element solvent molecules 102'. The second element solvent molecules 102' can be configured to have a relatively low molecular weight, and therefore the second element solvent 102 can have a low viscosity. When an electric field is formed in the light-emitting element ink 1000 after the second element solvent 102 is formed, a strong dielectric electrophoretic force can be applied to the light-emitting elements 30, and thus the light-emitting elements 30 can be placed on the electrodes 21 and 22 with a high degree of alignment. In addition, the second element solvent 102 containing molecules with a relatively low molecular weight can be easily removed during a subsequent low-temperature heat treatment process, thereby minimizing changes in the alignment state of the light-emitting elements 30 placed on the electrodes 21 and 22. That is, the element solvent 100 can have a viscosity that allows it to be sprayed from the nozzle while maintaining the dispersion of the light-emitting elements 30, but the viscosity of the element solvent 100 can be reduced in subsequent processes. This will be described in more detail later.

[0268] The element solvent molecule 100' according to the embodiment may have a structure of the following Formula 1:

[0269] [Formula 1]

[0270] X1-P-X2

[0271] wherein P is a photodegradable functional group 150 , X1 is a first functional group 110 , and X2 is a second functional group 120 .

[0272] Referring to Formula 1, the element solvent molecule 100' of the element solvent 100 according to the embodiment may include a photodegradable functional group 150 (P) and at least one functional group bonded to the photodegradable functional group 150 (P), for example, a first functional group 110 (X1) and a second functional group 120 (X2). When some bonds of the photodegradable functional group 150 (P) are decomposed, one or more photodegradable fragments or second photodegradable functional groups 152 may be formed, and each of the second photodegradable functional groups 152 may be bonded to the first functional group 110 (X1) or the second functional group 120 (X2). The element solvent molecule 100' may be formed into an element solvent molecule having a small molecular weight and low viscosity, that is, a second element solvent molecule 102', by degradation of the photodegradable functional group 150 (P).

[0273] In an embodiment, the photodegradable functional group 150 may be any one of, but is not limited to, a cyclobutyl group, a maleimide dimer, an acrylate dimer, and a carbonyl group.

[0274] The bonds of the photodegradable functional group 150 implemented as the above functional group can be decomposed by irradiated light to form photodegradable fragments as shown in the following chemical reaction formulas 1 to 4. That is, when the first photodegradable functional group 151 absorbs light, the bonds of the first photodegradable functional group 151 are decomposed to form the second photodegradable functional group 152. The element solvent molecule 100' or the first element solvent molecule 101' having a high molecular weight and viscosity can form the second element solvent molecule 102' having a low molecular weight and viscosity:

[0275] [Chemical reaction formula 1]

[0276]

[0277] [Chemical reaction formula 2]

[0278]

[0279] [Chemical reaction formula 3]

[0280]

[0281] [Chemical reaction formula 4]

[0282]

[0283] For example, as shown in chemical reaction formula 1, when photodegradable functional group 150 includes cyclobutyl group, each carbon (C) of cyclobutyl group can be separated into two olefin molecules by reverse-[2+2] cycloaddition. Therefore, the first photodegradable functional group 151 can be separated into two second photodegradable functional groups 152 (for example, two olefin molecules) with small molecular weight, and its molecular weight and viscosity can be reduced. In particular, when photodegradable functional group 150 is decomposed as shown in chemical reaction formulas 1 to 4, the first functional group 110 and the second functional group 120 are bonded to different second photodegradable functional groups 152. Each second element solvent molecule 102 'formed by light irradiation can be bonded to any one of the first functional group 110 and the second functional group 120, and can have low molecular weight and viscosity. Chemical reaction formulas 2 to 4 can also be understood in the same way, and therefore their detailed description is omitted.

[0284] In an embodiment, each of the first functional group 110 and the second functional group 120 may be a functional group represented by the following Chemical Formula 1:

[0285] [Chemical Formula 1]

[0286]

[0287] In Chemical Formula 1, n is an integer of 1 to 5, and R5 is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group.

[0288] Each of the first functional group 110 and the second functional group 120 may include at least one ethylene glycol (—OCH 2 C H 2 O—) monomer as shown in the above Chemical Formula 1. The first functional group 110 and the second functional group 120 may be bonded to the photodegradable functional group 150 and may have a molecular weight and viscosity sufficient for the element solvent 100 to disperse the light-emitting element 30. The value of n of each of the first functional group 110 and the second functional group 120 means the number of repeating units of the ethylene glycol monomer and may have an integer of 1 to 5, although it is not particularly limited.

[0289] However, in the element solvent molecule 100', in particular, in the first element solvent molecule 101' in which the photodegradable functional group 150 is not decomposed, the sum (n1+n2) of the value of n of the first functional group 110 (n1) and the value of n of the second functional group 120 (n2) may be 2 to 6. That is, in one element solvent molecule 100', the number of ethylene glycol monomers contained in the first functional group 110 and the second functional group 120 may be 2 to 6. When the sum (n1+n2) of the value of n of the first functional group 110 (n1) and the value of n of the second functional group 120 (n2) is 2 or less, the first element solvent molecule 101' may not have sufficient molecular weight and viscosity. Therefore, the light-emitting element 30 may not remain dispersed. When the sum (n1+n2) of the value of n (n1) of the first functional group 110 and the value of n (n2) of the second functional group 120 is greater than 6, the molecular weight and viscosity of the second element solvent molecule 102' formed by the degradation of the photodegradable functional group 150 can have large values, and the dielectrophoretic reactivity of the light-emitting element 30 can be reduced.

[0290] In an embodiment, the element solvent molecule 100' may be any one of the compounds represented by the following Chemical Formula 2 to Chemical Formula 5:

[0291] [Chemical Formula 2]

[0292]

[0293] [Chemical Formula 3]

[0294]

[0295] [Chemical Formula 4]

[0296]

[0297] [Chemical Formula 5]

[0298]

[0299] In Chemical Formulas 2 to 5, R1 and R2 are represented by Chemical Formula 1, the sum of the n value (n1) of R1 in Chemical Formula 1 and the n value (n2) of R2 in Chemical Formula 1 is 2 to 6, and each of R3 and R4 is independently C1-C 10 Alkyl groups, C2-C 10 Alkenyl groups, C2-C 10 Alkynyl groups, C1-C10 alkyl ether groups and C2-C 10 Any of the alkenyl ether groups.

[0300] Referring to Chemical Formulas 2 to 5, the element solvent 100 includes a functional group in which a bond can be decomposed by light irradiation and at least one functional group represented by Chemical Formula 1. In Chemical Formulas 2 to 5, R1 and R2 may include the functional group represented by Chemical Formula 1 and may be the first functional group 110 and the second functional group 120 of the element solvent molecule 100', respectively. R1 and R2, i.e., the first functional group 110 and the second functional group 120, are the same as described above.

[0301] R3 and R4 may be appropriately selected functional groups so that the element solvent 100 has a molecular weight sufficient to disperse the light emitting element 30. For example, each of R3 and R4 may independently be, but is not limited to, C1-C 10 Alkyl groups, C2-C 10 Alkenyl groups, C2-C 10 Alkynyl group, C1-C 10 Alkyl ether groups and C2-C 10 Any of the alkenyl ether groups.

[0302] For example, in the case of the compound of Chemical Formula 2, a cyclobutyl group may be included as a functional group in which a bond can be decomposed by light irradiation, and the first functional group 110 and the second functional group 120 may include a functional group in which ethylene glycol (—OCH 2 CH 2 O—) monomers are repeated.

[0303] In Chemical Formula 1, the cyclobutyl group can be decomposed into two olefin molecules via reverse-[2+2] cycloaddition by light irradiation. Each of the two olefin molecules thus formed includes the functional group in which ethylene glycol (-OCH2CH2O-) monomer is repeated. That is, the first photodegradable functional group 151 of the first element solvent molecule 101' can be a cyclobutyl group, and the second photodegradable functional group 152 formed by decomposing due to light irradiation can be an olefin group. The first functional group 110 and the second functional group 120 can each include ethylene glycol (-OCH2CH2O-) monomer, and can be bonded to the cyclobutyl group in the first element solvent molecule 101', but can be bonded to two different olefin groups in the second element solvent molecule 102'. The second element solvent molecule 102' is a compound with a smaller molecular weight than the first element solvent molecule 101', and therefore has a low viscosity, thereby increasing the dielectrophoretic reactivity of the dispersed light-emitting element 30. Furthermore, the second component solvent molecules 102 ′ can be easily removed by volatilization at a relatively low temperature in a subsequent process.

[0304] In an embodiment, the element solvent molecule 100' may include a compound represented by the following Chemical Formula 6:

[0305] [Chemical Formula 6]

[0306]

[0307] The element solvent molecule 100' can be represented by the above chemical formula 6 because the photodegradable functional group 150 is a 1,1,3,3-tetramethyl-cyclobutyl group, and the first functional group 110 and the second functional group 120 have 2 as the n value and a methyl (-CH3) group as R5 in the chemical formula 1. The compound represented by the chemical formula 6 can have a viscosity of 9 cp to 11 cp. Therefore, the light-emitting element 30 can be kept dispersed. In addition, by having a viscosity within the above range, the light-emitting element ink 1000 can be sprayed onto the electrodes 21 and 22 through the nozzle of the inkjet printing device.

[0308] When the element solvent molecule 100' is a compound represented by Chemical Formula 6, the photodegradable functional group 150 may be decomposed by the reaction in the following Chemical Reaction Formula 5:

[0309] [Chemical reaction formula 5]

[0310]

[0311] Referring to Chemical Reaction Formula 5, in the compound represented by Chemical Formula 6, the cyclobutyl group can be decomposed into two olefin molecules via a reverse-[2+2] cycloaddition by irradiation with light (hv). Each of the two olefin molecules contains an ethylene glycol monomer, which can be hydrolyzed (H3O + ) decomposes into diethylene glycol monomethyl ether (CH3OCH2CH2OCH2CH2OH) and isobutylaldehyde ((CH3)2CHCHO). That is, the element solvent molecule 100' may include a first element solvent molecule 101' represented by Chemical Formula 6, and the first photodegradable functional group 151 of the first element solvent molecule 101' may decompose to generate a second element solvent molecule 102' represented by diethylene glycol monomethyl ether (CH3OCH2CH2OCH2CH2OH) and isobutylaldehyde ((CH3)2CHCHO).

[0312] The first solvent molecule 101′ represented by Chemical Formula 6 has a relatively high molecular weight and viscosity. Since the second solvent molecule 102′ formed by the decomposition of the cyclobutyl group has a low molecular weight and viscosity, the dielectrophoretic reactivity of the light-emitting element 30 can be increased, and the second solvent 102 can be easily removed in a subsequent process.

[0313] In the embodiment, in the element solvent 100, the first element solvent molecule 101′ before the photodegradable functional group 150 is decomposed may have a molecular weight of 300 g / mol to 800 g / mol, and the first element solvent 101 may have a boiling point of 350° C. to 400° C. and a viscosity of 7 cp to 15 cp. The second element solvent molecule 102′ formed by partial decomposition of the bond of the photodegradable functional group 150 may have a molecular weight of 50% or less of the molecular weight of the first element solvent molecule 101′, and the second element solvent 102 may have a boiling point of 50° C. to 200° C. and a viscosity of 5 cp or less.

[0314] When the molecular weight of the first solvent molecule 101' increases, the first solvent 101 can maintain the dispersion of the light-emitting elements 30, which have a large specific gravity, for a certain period of time. When the molecular weight of the first solvent molecule 101' is 300 g / mol or less, the light-emitting elements 30 cannot remain dispersed after the light-emitting element ink 1000 is manufactured. Therefore, the light-emitting element ink 1000 may be ejected as a non-uniform dispersion through the nozzle of the inkjet printing device. In addition, when the molecular weight of the first solvent molecule 101' is a large value of 800 g / mol or more, the second solvent molecule 102' formed by decomposition of the photodegradable functional group 150 upon light irradiation may also have a high molecular weight and viscosity, thereby reducing the dielectrophoretic reactivity of the light-emitting element 30.

[0315] On the other hand, the first element solvent molecules 101 ′ according to the embodiment may have a molecular weight within the above range, and the second element solvent molecules 102 ′ formed by decomposition of the photodegradable functional groups 150 may have low molecular weight and viscosity.

[0316] A method for manufacturing the display device 10 according to the embodiment will now be described.

[0317] Figure 11 is a flowchart illustrating a method for manufacturing a display device according to the embodiment.

[0318] refer to Figure 11 , a method for manufacturing a display device 10 includes: preparing a target substrate SUB and a first electrode 21 and a second electrode 22 disposed on the target substrate SUB, spraying a light-emitting element ink 1000 containing a first element solvent 100 dispersed therein with light-emitting elements 30 on the first electrode 21 and the second electrode 22, forming a second element solvent 102 by removing at least some chemical bonds contained in the first element solvent 100, and mounting the light-emitting element 30 on the first electrode 21 and the second electrode 22.

[0319] The method for manufacturing the display device 10 according to the embodiment may include: spraying a light-emitting element ink 1000 including a first element solvent 101 and light-emitting elements 30 dispersed in the first element solvent 101 on a target substrate SUB having a first electrode 21 and a second electrode 22 formed thereon (operation S100), forming a second element solvent 102 in which at least some bonds of the first element solvent 101 are decomposed by irradiating light (UV) to the first element solvent 101 and mounting the light-emitting elements 30 on the first electrode 21 and the second electrode 22 (operation S200), and removing the second element solvent 102 (operation S300).

[0320] As described above, the display device 10 can be manufactured by ejecting the light-emitting element ink 1000 using an inkjet printing device and placing the light-emitting element 30 on the electrodes 21 and 22. Here, the element solvent 100 in which the light-emitting element 30 is dispersed may include a first element solvent 101 having a viscosity capable of maintaining a dispersed state. However, in order to improve the alignment when the light-emitting element 30 is installed (operation S200), the method for manufacturing the display device 10 according to the embodiment may include forming a second element solvent 102 by irradiating light to the first element solvent 101. The formation of the second element solvent 102 having a lower viscosity than the first element solvent 101 can improve the dielectrophoretic reactivity of the light-emitting element 30 and minimize the change in the alignment state of the light-emitting element 30 that occurs when the second element solvent 102 is removed.

[0321] Now refer to Figures 12 to 23 A method for manufacturing a display device according to the embodiment is described in detail.

[0322] Figure 12 and Figure 13 is a cross-sectional view illustrating a portion of a method for manufacturing a display device according to the embodiment.

[0323] First, refer to Figure 12 , a target substrate SUB on which the first electrode 21 and the second electrode 22 are formed is prepared (operation S100). In the following figures, for ease of description, only the electrodes 21 and 22 and the light-emitting element 30 provided on the target substrate SUB are illustrated. However, the display device 10 is not limited thereto and may include more components, such as the inner blocks 41 and 42, the outer block 45, and the contact electrode 26 as described above.

[0324] Then, refer to Figure 13, a light-emitting element ink 1000 containing the light-emitting element 30 is sprayed onto the first electrode 21 and the second electrode 22. The light-emitting element ink 1000 may contain an element solvent 100, and the light-emitting element 30 may be dispersed in the element solvent 100. In the embodiment, the light-emitting element ink 1000 may be provided in a solution or colloidal state. The element solvent 100 of the light-emitting element ink 1000 sprayed onto the electrodes 21 and 22 may be the first element solvent 101 containing the first photodegradable functional group 151 in which the bond is not decomposed as described above. The first element solvent 101 may have a relatively high molecular weight and viscosity and may be sprayed onto the electrodes 21 and 22 while keeping the light-emitting element 30 dispersed.

[0325] Then, the light emitting element 30 is installed between the first electrode 21 and the second electrode 22 (operation S200). The installation of the light emitting element 30 (operation S200) may include forming an electric field EL in the light emitting element ink 1000 by transmitting an electric signal to the first electrode 21 and the second electrode 22, and placing the light emitting element 30 on the electrodes 21 and 22 by the dielectrophoretic force F applied by the electric field.

[0326] As illustrated in the drawings, when an alternating current (AC) power source is applied to the electrodes 21 and 22, an electric field EL may be formed in the light-emitting element ink 1000 ejected onto the electrodes 21 and 22. The electric field EL may apply a dielectrophoretic force to the light-emitting element 30, and the light-emitting element 30 to which the dielectrophoretic force has been applied may be placed on the first and second electrodes 21 and 22.

[0327] However, since the first element solvent 101 contains first element solvent molecules 101' having a large molecular weight, its viscosity has a large value. The light emitting element 30 may experience a weak dielectrophoretic force F1 in the first element solvent 101 having a high viscosity and may be placed on the electrodes 21 and 22 with uneven alignment.

[0328] Figures 14 to 16 is a schematic diagram illustrating a process in which a light-emitting element dispersed in an element solvent is placed on an electrode according to the embodiment.

[0329] refer to Figure 14 and Figure 15 , the first element solvent 101 and the light emitting elements 30 are sprayed on the electrodes 21 and 22, and the electric field EL is formed by applying AC power through the electrodes 21 and 22. The light emitting elements 30 can receive the dielectrophoretic force F1 applied by the electric field EL and move from their initial scattered positions (at Figure 12 The light emitting element 30 (indicated by dotted lines) moves toward the electrodes 21 and 22. However, the light emitting element 30 may experience resistance of the first element solvent 101 having high viscosity, and thus a relatively weak dielectrophoretic force F1 may be applied to the light emitting element 30.

[0330] refer to Figure 16 By applying AC power to the first electrode 21 and the second electrode 22, an electric field EL can be formed on the first element solvent 101. A dielectrophoretic force F1 caused by the electric field EL can be applied to the light-emitting element 30, thereby aligning the light-emitting element 30 toward the electrodes 21 and 22. As described above, the first element solvent 101 can have a high viscosity by containing first element solvent molecules 101' having a relatively large molecular weight. Due to the resistance of the first element solvent 101 having a high viscosity, a weak dielectrophoretic force F1 is applied to the light-emitting element 30.

[0331] As illustrated in the drawings, some light-emitting elements 30 may not be disposed on the electrodes 21 and 22. Furthermore, even if both ends of the light-emitting elements 30 are disposed on the electrodes 21 and 22, the direction in which each light-emitting element 30 extends and the acute angle formed by the electrodes 21 and 22 may not be constant. The dielectrophoretic force F1 applied by the electric field EL may not have sufficient strength to align the light-emitting elements 30 dispersed in the first component solvent 101 having a high viscosity with a uniform degree of alignment.

[0332] Furthermore, when the first component solvent 101 is directly volatilized and removed in a subsequent process, the orientation or alignment state of the light emitting element 30 may be changed by the first component solvent 101 having high viscosity, or the first component solvent 101 may not be completely removed.

[0333] Figure 17 is a plan view illustrating a state in which a solvent of an element has been removed according to the embodiment. Figure 18 is a cross-sectional view illustrating a state in which a solvent of an element has been removed according to the embodiment.

[0334] refer to Figure 17 , when the first element solvent 101 is removed, a fluid dynamic force Fa can be applied in one direction to the light emitting elements 30 in the first element solvent 101 mounted on the electrodes 21 and 22. The first element solvent 101 having a high viscosity can apply a strong fluid dynamic force Fa to the light emitting elements 30 when being removed by volatilization, and the light emitting elements 30 can be moved from their initial alignment positions (at Figure 17 21 and 22 are moved. Therefore, the alignment state of the light-emitting element 30 can be changed. Therefore, the acute angle θi' formed by the direction in which the light-emitting element 30 finally mounted on the electrodes 21 and 22 extends and the direction perpendicular to the direction in which the electrodes 21 and 22 extend can have a large value. The acute angle θi' can be 20 degrees or more. Therefore, the acute angle formed by the direction in which the light-emitting element 30 extends and the direction in which the electrodes 21 and 22 extend can be 80 degrees or less.

[0335] refer to Figure 18 First solvent 101 contains first solvent molecules 101' having a large molecular weight. Therefore, even after volatilization, some residue may remain. This residue may become an impurity in display device 10 and cause contact failure with light-emitting element 30 during the subsequent process of forming contact electrode 26.

[0336] On the other hand, the method for manufacturing the display device 10 according to the embodiment includes forming the second element solvent 102 by irradiating light UV to the first element solvent 101 before installing the light-emitting element 30 (operation S200). When the light UV is irradiated to the first element solvent 101, the chemical bond of the first photodegradable functional group 151 is decomposed to form a photodegradable fragment, that is, the second photodegradable functional group 152. The first element solvent molecule 101' can form a second element solvent molecule 102' containing the second photodegradable functional group 152 and the first functional group 110 or the second functional group 120 bonded to the second photodegradable functional group 152. The second element solvent molecule 102' can have a smaller molecular weight than the first element solvent molecule 101' and can form a second element solvent 102 with low viscosity. The light-emitting element 30 can be dispersed in the second element solvent 102 with low viscosity, and its orientation direction can be aligned on the electrodes 21 and 22 by the strong dielectrophoretic force F2 applied by the electric field EL.

[0337] Figure 19 is a schematic diagram illustrating an operation of forming a second element solvent according to an embodiment.

[0338] refer to Figure 19 , by irradiating UV light to the first solvent 101, the second solvent 102 is formed. The first solvent 101 may include a first photodegradable functional group 151, and the bonds of the first photodegradable functional group 151 can be decomposed by the irradiated UV light to form photodegradable fragments or second photodegradable functional groups 152. The first solvent molecules 101' can form second solvent molecules 102' having a small molecular weight. Therefore, the light-emitting element 30 can be dispersed in the second solvent 102 having a relatively low viscosity, and because the resistance of the solvent is reduced, a strong dielectrophoretic force F2 can be applied to the light-emitting element 30 via the electric field EL.

[0339] Figures 20 to 22 is a schematic diagram illustrating a process in which a light-emitting element dispersed in an element solvent is placed on an electrode according to the embodiment.

[0340] refer to Figures 20 to 22Since the second element solvent 102 has a low viscosity, the dielectrophoretic force F2 applied to the light emitting element 30 by the electric field EL can have a strong intensity. The light emitting elements 30 can have a high intensity from their initial ejection position (at Figure 19 The two ends of the light emitting element 30 (indicated by dotted lines in the figure) move toward the electrodes 21 and 22 and can be oriented with a relatively uniform alignment. As illustrated in the accompanying drawings, the two ends of most of the light emitting elements 30 can be set on the electrodes 21 and 22. Specifically, the acute angle formed by the direction in which the light emitting element 30 extends and the direction of the electrodes 21 and 22 can be constant. The method for manufacturing the display device 10 according to the embodiment may include forming a second element solvent 102 by irradiating light UV to a first element solvent 101, and the light emitting element 30 can be aligned in the second element solvent 102 having a low viscosity. That is, a display device 10 having a light emitting element 30 with improved dielectrophoretic reactivity and improved alignment can be manufactured.

[0341] Finally, when the light emitting element 30 is aligned on the electrodes 21 and 22 , the element solvent 100 , ie, the second element solvent 102 , is removed.

[0342] Figure 23 is a cross-sectional view illustrating an operation of removing a second member solvent according to an embodiment. Figure 24 is a plan view illustrating alignment of light emitting elements according to the embodiment.

[0343] refer to Figure 23 and 24 , the element solvent 100 can be removed by performing conventional methods. The second element solvent 102 has a low viscosity by containing a compound having a smaller molecular weight than the first element solvent 101, and can be removed by volatilization at a relatively low temperature. For example, the second element solvent 102 can be removed by methods such as heat treatment or infrared irradiation.

[0344] The light emitting element 30 in the second element solvent 102 with low viscosity can be subjected to a strong dielectrophoretic force F2 and can therefore be oriented with a relatively uniform degree of alignment. In addition, even if removed by volatilization, the second element solvent 102 can also apply a weak fluid dynamic force to the aligned light emitting element 30. Therefore, the acute angle θi formed by the direction in which the light emitting element 30 ultimately mounted on the electrodes 21 and 22 extends and the direction perpendicular to the direction in which the electrodes 21 and 22 extend can have a very small value. The acute angle θi can be 5 degrees or greater than 5 degrees. Therefore, the acute angle formed by the direction in which the light emitting element 30 extends and the direction in which the electrodes 21 and 22 extend can be 85 degrees or greater than 85 degrees. For example, the acute angle formed by the direction in which the light emitting element 30 extends and the direction in which the electrodes 21 and 22 extend can be 88 to 90 degrees. However, the present disclosure is not limited thereto.

[0345] Through the above process, the display device 10 including the light emitting element 30 can be manufactured. However, the method for manufacturing the display device 10 is not limited thereto. Since the display device 10 includes more components as described above, more processes can be performed, but detailed descriptions thereof will be omitted.

[0346] As described above, the light emitting element 30 may be dispersed in the element solvent 100 (see Figure 8 ) is ejected onto the electrodes 21 and 22 in the state of , and can be placed between the electrodes 21 and 22 by transmitting an alignment signal to the electrodes 21 and 22.

[0347] However, since each of the light-emitting elements 30 includes a plurality of semiconductor layers, it can be made of a material having a larger specific gravity than the element solvent 100. The light-emitting elements 30 may remain dispersed in the element solvent 100 for a certain period of time and then gradually settle. To prevent this, if the light-emitting elements 30 are kept dispersed for a long time by adjusting the viscosity of the element solvent 100, the element solvent 100 may not be ejected through the nozzle during the inkjet printing process. In addition to the element solvent 103 and the light-emitting elements 30 dispersed in the element solvent 103, the light-emitting element ink 1001 according to the embodiment (see Figure 25 ) may contain a photodegradable thickener 500 (see Figure 25 ). When stored in a container or when no shear stress is applied, the light-emitting element ink 1001 containing the photodegradable thickener 500 can have a high viscosity, and thus the light-emitting element 30 can be dispersed for a long time. In addition, when shear stress is applied during inkjet printing, the light-emitting element ink 1001 can have a low viscosity and thus can be smoothly ejected from the nozzle.

[0348] Figure 25 is a schematic diagram of a light-emitting element ink according to the embodiment.

[0349] refer to Figure 25 The light emitting element ink 1001 according to the embodiment includes an element solvent 103, a light emitting element 30, and a photodegradable thickener 500. Since the light emitting element 30 is the same as those described above, the element solvent 103 and the photodegradable thickener 500 will be described in detail below.

[0350] The element solvent 103 may store the light emitting element 30 in a dispersed state and may include a material that does not react with the light emitting element 30. The element solvent 103 may include a material having a viscosity that allows the element solvent 103 to be ejected through the nozzle of the inkjet printing device. The element solvent 103 to be described in the following embodiments may be different from the above reference Figures 8 to 24The element solvent 100 is described. For example, the element solvent 103 may be, but is not limited to, an organic solvent such as acetone, water, ethanol, toluene, propylene glycol (PG), or propylene glycol methyl acetate (PGMA).

[0351] The photodegradable thickener 500 can be dispersed in the element solvent 103 together with the light-emitting element 30. As described above, the light-emitting element ink 1001 can have a high viscosity when stored in a container to keep the light-emitting element 30 dispersed, and can have a low viscosity when ejected through a nozzle. According to the embodiment, the photodegradable thickener 500 can form intermolecular hydrogen bonds. Each of the photodegradable thickeners 500 can contain a functional group that can form hydrogen bonds, and when no shear stress is applied, the light-emitting element ink 1001 can have a high viscosity due to the intermolecular hydrogen bonds formed by the photodegradable thickener 500. The light-emitting element 30 can remain dispersed in the light-emitting element ink 1001 having a high viscosity for a long time.

[0352] On the other hand, when the light-emitting element ink 1001 is ejected through the nozzle or flows in the inkjet head of the inkjet printing device, shear stress can be applied to the element solvent 103. The shear stress can have a stronger strength than the intermolecular hydrogen bonds of the photodegradable thickener 500, and the hydrogen bonds can be broken. Therefore, the light-emitting element ink 1001 can have a low viscosity and can be smoothly ejected through the nozzle.

[0353] However, during the process of manufacturing the display device 10, a process of removing the element solvent 103 and the photodegradable thickener 500 by irradiating heat or light to the light-emitting element ink 1001 may be performed after the light-emitting element 30 is placed between the electrodes 21 and 22. The light-emitting element ink 1001 sprayed onto the electrodes 21 and 22 may be in a state where no shear stress is applied, and may have a high viscosity due to intermolecular hydrogen bonds of the photodegradable thickener 500. Therefore, the element solvent 103 and the photodegradable thickener 500 may not be removed smoothly and may remain as foreign matter on the electrodes 21 and 22 or the light-emitting element 30. Furthermore, since the light-emitting element ink 1001 has a high viscosity, the strength of the dielectrophoretic force acting on the light-emitting element 30 due to the electric field formed on the electrodes 21 and 22 may be insufficient. In addition, high-temperature heat treatment may be required to remove the element solvent 103 and the photodegradable thickener 500 having high viscosity, and when removing them, 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 photodegradable thickener 500 and the light-emitting element 30.

[0354] Each photodegradable thickener 500 according to the embodiment may contain a functional group that can form intermolecular hydrogen bonds and a photodegradable functional group in which the bond decomposes upon exposure to light. When light is irradiated to the light-emitting element ink 1001 after the light-emitting element 30 is placed between the electrodes 21 and 22 or while an electric field is generated, the bond of the photodegradable functional group of each photodegradable thickener 500 can be broken into monomers with a small molecular weight. Due to the decomposition of the photodegradable thickener 500, the light-emitting element ink 1001 can also have a low viscosity even when no shear stress is applied. Therefore, the light-emitting element 30 can be smoothly aligned by the electric field formed on the electrodes 21 and 22, and the element solvent 103 and the photodegradable thickener 500 can be completely removed even at relatively low temperatures.

[0355] The photodegradable thickener 500 according to the embodiment may include a third functional group that can form an intermolecular hydrogen bond and a photodegradable functional group in which the intramolecular bond can be decomposed by light irradiation. In some embodiments, the photodegradable thickener 500 may be a polymer formed by polymerization of a monomer including a third functional group and a photodegradable functional group, and may be represented by the following Formula 2:

[0356] [Formula 2]

[0357]

[0358] In Formula 2, "HP1" is a third functional group, "CP" is a photodegradable functional group, m is an integer from 1 to 3, and l is an integer from 10 to 100. The photodegradable thickener 500 having the structure of Formula 2 may have a chain structure in which the third functional group and the photodegradable functional group are repeated.

[0359] The third functional group may include a functional group that can form intermolecular hydrogen bonds. For example, the third functional group may include a hydroxyl group (-OH) or a primary amine group (-NH2). The photodegradable thickener 500 containing the third functional group can form intermolecular hydrogen bonds. The photodegradable thickener 500 dispersed in the element solvent 103 can form a network structure between polymer chains. Due to the formation of the network structure by the photodegradable thickener 500, the light-emitting element ink 1001 can have a high viscosity.

[0360] In addition, in some embodiments, the third functional group can be a polymerizable group that can form hydrogen bonds and polymer chains. For example, the third functional group can be any one of a secondary amine group (-NH-), an acylamino group (-CONH-), a urea group (-NHCONH-) and a carbamate group (-NHCOO-). As a functional group capable of polymerization, the third functional group can form the main chain of the polymer chain and can also form intramolecular hydrogen bonds. The photodegradable thickener 500 can form a network structure by intramolecular hydrogen bonds between the main chains of the polymer chain.

[0361] When the third functional group is a functional group capable of polymerization reaction, the photodegradable functional group may be directly bonded to the third functional group, as shown in Formula 2. However, the present disclosure is not limited thereto. When the photodegradable thickener 500 further includes other functional groups, at least one functional group may be further bonded between the third functional group and the photodegradable functional group.

[0362] The photodegradable functional group may include a functional group whose bonds can be decomposed by light irradiation. After the light-emitting element 30 is placed between the electrodes 21 and 22, or while an electric field is generated across the electrodes 21 and 22, some bonds of the photodegradable functional groups of the photodegradable thickener 500 can be decomposed by light irradiation. As a result, the photodegradable thickener 500 can be decomposed into multiple fragments with low molecular weight, and thus can have low viscosity even when no shear stress is applied to the light-emitting element ink 1001.

[0363] In an embodiment, the photodegradable functional group may include any one of a cyclobutyl group, a maleimide dimer, an acrylate dimer, and a carbonyl group. The bonds of the above functional groups may be decomposed by irradiated light as shown in the above chemical reaction formulas 1 to 4 to form fragments with small molecular weight.

[0364] The structure of the photodegradable thickener 500 is not limited to the above formula 2. The photodegradable thickener 500 may further include a functional group for adjusting the molecular weight and a polymerizable group for forming a polymer chain. In this case, the photodegradable thickener 500 may be a polymer formed by polymerization of a monomer including another functional group or a polymerizable group in addition to the third functional group and the photodegradable functional group, and may be represented by the following formulas 3 to 5:

[0365] [Formula 3]

[0366]

[0367] [Formula 4]

[0368]

[0369] [Formula 5]

[0370]

[0371] In Formulas 3 to 5, "HP1" and "HP2" are third functional groups, "CP" is a photodegradable functional group, "R6" is a functional group for molecular weight control, "R7" is a polymerizable group, m is an integer from 1 to 3, and l is an integer from 10 to 100. The photodegradable thickener 500 may have a chain structure in which monomers including a plurality of functional groups, a photodegradable functional group, and a polymerizable group as shown in Formulas 3 to 5 are repeated.

[0372] As shown in Formula 3, the photodegradable thickener 500 may further include a functional group R6 that can adjust the viscosity of the light-emitting element ink 1001 by molecular weight control. In some embodiments, R6 can be any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group. The third functional group may include a functional group capable of forming a hydrogen bond and capable of polymerization reaction, as described above. The third functional group may be directly bonded to R6, and the photodegradable functional group may be directly bonded to the third functional group. However, the present disclosure is not limited thereto, and the photodegradable functional group may also be directly bonded to R6. The photodegradable thickener 500 can control the molecular weight by adjusting the number of carbon atoms, n, and l.

[0373] The third functional group may not necessarily be a functional group capable of polymerization reaction. As shown in Formula 4 and Formula 5, the third functional group may only include a functional group that can form a hydrogen bond, and the photodegradable thickener 500 may include a polymerizable group R7 capable of polymerization reaction. In an embodiment, the third functional group "HP2" may be a hydroxyl group (-OH) or an amine group (-NH2), and R7 may be any one of an acryloyl group, a methacryloyl group, an ester group, and a carbonate group. However, the present disclosure is not limited thereto.

[0374] The photodegradable thickener 500 can form a polymer chain through a polymerization reaction of the polymerizable group R7, and the third functional group can be bonded to the polymerizable group. In the photodegradable thickener 500, the polymerizable group and the photodegradable functional group can form the main chain of the polymer chain, and the third functional group can form a side chain. The photodegradable thickener 500 can form a network structure through intermolecular hydrogen bonds between the side chains of the polymer chain.

[0375] In some embodiments, the photodegradable thickener 500 may be represented by the following Chemical Formulas 7 to 11:

[0376] [Chemical Formula 7]

[0377]

[0378] [Chemical Formula 8]

[0379]

[0380] [Chemical Formula 9]

[0381]

[0382] [Chemical Formula 10]

[0383]

[0384] [Chemical Formula 11]

[0385]

[0386] In Chemical Formulae 7 to 11, l is an integer from 10 to 100.

[0387] Each of Chemical Formulas 7 to 11 includes a first functional group capable of forming an intermolecular hydrogen bond and a photodegradable functional group in which the bond can be decomposed by light irradiation. In addition, the photodegradable thickener 500 may include a functional group capable of adjusting molecular weight and a polymerizable group capable of polymerization reaction.

[0388] Figure 26 is a schematic diagram illustrating the arrangement of a photodegradable thickener in a state in which shear stress is not applied to the light emitting element ink according to the embodiment. Figure 27 is a schematic diagram illustrating the arrangement of a photodegradable thickener in a state where shear stress has been applied to the light emitting element ink according to the embodiment.

[0389] Will refer to Figure 26 and Figure 27 A case is described in which each of the photodegradable thickeners 500 is Chemical Formula 8. In each of the photodegradable thickeners 500, the third functional group may be an amide group (—CONH—) capable of forming a hydrogen bond and capable of a polymerization reaction, the photodegradable functional group may include a cyclobutyl group, and an ethylene group (—CH 2 CH 2 —) may be included as a functional group for molecular weight control.

[0390] When no shear stress is applied, the photodegradable thickener 500 can form a three-dimensional (3D) network structure in the light-emitting element ink 1001 because its tertiary functional groups form intermolecular hydrogen bonds. When the photodegradable thickener 500 forms a network structure, the light-emitting element ink 1001 can have high viscosity.

[0391] For example, when no shear stress is applied, the light-emitting element ink 1001 may have a viscosity of 30 cP to 70 cP. However, the present disclosure is not limited thereto. In the above chemical formula 8, l can be appropriately adjusted according to the viscosity range required for the light-emitting element ink 1001. When l increases, the molecular weight and polymer chain length of the photodegradable thickener 500 and the network structure formed by the photodegradable thickener 500 can increase, and the light-emitting element ink 1001 can have a greater viscosity. When the light-emitting element ink 1001 containing the photodegradable thickener 500 is stored in a container, it can keep the light-emitting element 30 dispersed for a long time.

[0392] On the other hand, when the light-emitting element ink 1001 is ejected through the nozzle of the inkjet printing device or when shear stress is applied, the photodegradable thickener 500 may not form a network structure. When the light-emitting element ink 1001 flows in the inkjet head of the inkjet printing device or is ejected from the nozzle, shear stress caused by the flow of the fluid may be applied. The shear stress can be stronger than the intermolecular hydrogen bonds formed by the photodegradable thickener 500, and the photodegradable thickener 500 can remain in a separately dispersed state without forming a 3D structure. Therefore, the light-emitting element ink 1001 can have a low viscosity and can be smoothly ejected through the nozzle.

[0393] According to the embodiment, when shear stress is applied, the light-emitting element ink 1001 may have a viscosity of 5 cP to 15 cP or 7 cP to 13 cP, preferably about 10 cP. However, the present disclosure is not limited thereto, and the viscosity of the light-emitting element ink 1001 may be varied within the range in which the light-emitting element ink 1001 can be ejected from the nozzle of the inkjet head. As described above, the molecular weight and polymer chain length of the photodegradable thickener 500 may vary according to the value of n in Chemical Formula 2, and the viscosity of the light-emitting element ink 1001 may be adjusted to be within a desired range.

[0394] Figure 28 is a schematic diagram illustrating a photodegradable thickener when light is irradiated to the light emitting element ink according to the embodiment.

[0395] refer to Figure 28 When the photodegradable functional groups are decomposed, each photodegradable thickener 500 can form a plurality of fragment molecules 500' having a small molecular weight. When irradiated with light, Chemical Formula 8 can be separated into a plurality of fragments, as shown in the following Chemical Reaction Formula 6:

[0396] [Chemical reaction formula 6]

[0397]

[0398] When the bonds of the photodegradable functional groups are broken down, the photodegradable functional groups can be converted into functional group fragments CP1 and CP2 (see Figure 28 ) is retained in the fragment molecules 500'. When light is irradiated to the light-emitting element ink 1001, the polymer chains of the photodegradable thickener 500 can be decomposed. Therefore, even if shear stress is not applied, a network structure between the photodegradable thickeners 500 may not be formed, and the light-emitting element ink 1001 can have a low viscosity. Since the light-emitting element ink 1001 has a low viscosity after being sprayed on the electrodes 21 and 22, the light-emitting element 30 can be smoothly aligned and placed on the electrodes 21 and 22 by the dielectrophoretic force. In addition, the initial alignment position of the light-emitting element 30 may not change during the process of removing the element solvent 103 and the photodegradable thickener 500, and the element solvent 103 and the photodegradable thickener 500 can be completely removed at a relatively low temperature.

[0399] According to the embodiment, the viscosity of the light-emitting element ink 1001 containing the photodegradable thickener 500 can be changed during the process of manufacturing the display device 10. The light-emitting element ink 1001 can have an appropriate viscosity in each of the operations of storing the light-emitting element ink 1001, ejecting the light-emitting element ink 1001 through the nozzles of the inkjet head, aligning the light-emitting elements 30, and removing the element solvent 103 and the photodegradable thickener 500. In particular, the light-emitting element ink 1001 can have a high viscosity during storage, thereby preventing precipitation of the light-emitting elements 30. The light-emitting element ink 1001 can have a low viscosity during ejection of the light-emitting element ink 1001 through the nozzles, aligning the light-emitting elements 30, and removing the element solvent 103, thereby facilitating the inkjet printing process and alignment process of the light-emitting elements 30. Furthermore, during the process of manufacturing the display device 10 including the light-emitting element 30, the light-emitting element 30 can have a high degree of alignment between the electrodes 21 and 22, and the product reliability of the display device 10 can be improved.

[0400] Since each photodegradable thickener 500 according to the embodiment includes a third functional group and a photodegradable functional group, its molecular structure in the element solvent 103 can be changed by application of shear stress or irradiation of light. Since the light-emitting element ink 1001 includes the photodegradable thickener 500 in addition to the element solvent 103 and the light-emitting element 30, it can have an appropriate viscosity according to the process of manufacturing the display device 10.

[0401] A method for manufacturing the display device 10 according to the embodiment will now be described.

[0402] Figure 29 is a flowchart illustrating a method for manufacturing a display device according to the embodiment.

[0403] refer to Figure 29 According to the embodiment, the method for manufacturing the display device 10 may include: preparing a light-emitting element ink 1001 including an element solvent 103, a light-emitting element 30 and a photodegradable thickener 500 (operation S101), preparing a target substrate having electrodes 21 and 22 formed thereon and spraying the light-emitting element ink 1001 on the electrodes 21 and 22 (operation S201), and irradiating light to the light-emitting element ink 1001 and mounting the light-emitting element 30 on the first electrode 21 and the second electrode 22 (operation S301).

[0404] The light-emitting element ink 1001 can have low viscosity when it is sprayed onto the electrodes 21 and 22 because shear stress is applied. Therefore, a smooth spraying process can be performed. However, the light-emitting element ink 1001 sprayed onto the electrodes 21 and 22 is in a state where shear stress is not applied. Therefore, the light-emitting element ink 1001 can have high viscosity because the photodegradable thickener 500 forms a 3D network structure.

[0405] According to the embodiment, the process of manufacturing the display device 10 may include: during the process of mounting the light-emitting element 30 on the electrodes 21 and 22, irradiating light to the light-emitting element ink 1001 to decompose each photodegradable thickener 500 into a plurality of fragment molecules 500'. When the light-emitting element 30 is mounted on the electrodes 21 and 22, the light may be irradiated, thereby reducing the viscosity of the light-emitting element ink 1001. As a result, the light-emitting element 30 can be smoothly aligned between the electrodes 21 and 22, and the element solvent 103 and the photodegradable thickener 500 can be completely removed in a subsequent process.

[0406] Figures 30 to 32 is a cross-sectional view illustrating operations in a process of manufacturing a display device according to an embodiment.

[0407] First, refer to Figure 30 , a light-emitting element ink 1001 including a light-emitting element 30, an element solvent 103, and a photodegradable thickener 500, and a target substrate SUB having a first electrode 21 and a second electrode 22 disposed thereon are prepared. Although a pair of electrodes is disposed on the target substrate SUB in the drawings, more electrode pairs may be disposed on the target substrate SUB. In addition to the first substrate 11 of the display device 10 described above, the target substrate SUB may include a plurality of circuit elements disposed thereon, but for ease of description, these will not be illustrated below.

[0408] The light-emitting element ink 1001 may include an element solvent 103, and the light-emitting element 30 and the photodegradable thickener 500 dispersed in the element solvent 103. The light-emitting element ink 1001 stored in the container may be in a state where there is no fluid flow and no shear stress applied. The photodegradable thickener 500 may form a 3D network structure in the element solvent 103 when its first functional group forms intermolecular hydrogen bonds. The light-emitting element ink 1001 may have a high viscosity of, for example, 30 to 70 cps, and may maintain the light-emitting element 30 dispersed for a long period of time.

[0409] Then, refer to Figure 31 and Figure 32 , the light-emitting element ink 1001 is ejected onto the first electrode 21 and the second electrode 22 provided on the target substrate SUB. In the embodiment, the light-emitting element ink 1001 can be ejected onto the electrodes 21 and 22 by a printing process using an inkjet printing device. The light-emitting element ink 1001 can be ejected through the nozzle of the inkjet head included in the inkjet printing device. The light-emitting element ink 1001 can flow along the internal flow path provided in the inkjet head and can be ejected onto the target substrate SUB through the nozzle.

[0410] The light-emitting element ink 1001 flowing along the internal flow path may be in a state where the fluid flows and a state where shear stress is applied. In the light-emitting element ink 1001 to which shear stress is applied, the third functional group of the photodegradable thickener 500 may not form an intermolecular hydrogen bond. The photodegradable thickener 500 may have its respective chains dispersed in the element solvent 103 without forming a 3D network structure, and the light-emitting element ink 1001 may have a low viscosity of, for example, 5 cp to 15 cp or about 10 cp. The light-emitting element ink 1001 having a viscosity within the above range can be smoothly ejected from the nozzle of the inkjet head, and the nozzle clogging phenomenon caused by the viscosity of the solution can be prevented.

[0411] like Figure 32 , the light emitting element ink 1001 may be mounted on the electrodes 21 and 22 provided on the target substrate SUB. The light emitting elements 30 may extend in one direction and may be dispersed in the light emitting element ink 1001, wherein the extending direction thereof has a random orientation direction.

[0412] When the light-emitting element ink 1001 containing the light-emitting element 30 is ejected onto the target substrate SUB, an electric field EL is generated on the target substrate SUB by transmitting an alignment signal to the electrodes 21 and 22. The light-emitting element 30 dispersed in the element solvent 103 can be subjected to the dielectrophoretic force applied by the electric field EL and can be placed on the electrodes 21 and 22 while changing its orientation direction and position.

[0413] However, the light-emitting element ink 1001 ejected onto the target substrate SUB is in a state where no shear stress is applied because there is no fluid flow, and the photodegradable thickener 500 can form a 3D network structure by forming intermolecular hydrogen bonds. The light-emitting element ink 1001 can have a high viscosity, and the light-emitting element 30 may not be positioned at a desired position on the electrodes 21 and 22 even when subjected to a dielectrophoretic force applied by the electric field EL.

[0414] Figures 33 to 35 is a schematic diagram illustrating a process of placing a light-emitting element on an electrode during a process of manufacturing a display device. Figure 35 The process of removing the element solvent 103 and the photodegradable thickener 500 after the light emitting element 30 is placed on the electrodes 21 and 22 is illustrated.

[0415] First, refer to Figure 33 and Figure 34 , when an electric field EL is generated on the target substrate SUB in a state where a 3D network structure has been formed by the photodegradable thickener 500, the light emitting element 30 may be subjected to a dielectrophoretic force F1. In some embodiments, when the electric field EL formed on the target substrate SUB is parallel to the upper surface of the target substrate SUB, the light emitting element 30 may be aligned and placed on the first electrode 21 and the second electrode 22 so that its extension direction is parallel to the target substrate SUB. The light emitting element 30 may be moved from its initial dispersed position (at Figure 34 The light-emitting element 30 moves toward the electrodes 21 and 22 (indicated by dotted lines in the figure). However, the light-emitting element 30 may experience resistance acting in the opposite direction to the dielectrophoretic force F1 in the light-emitting element ink 1001 having high viscosity, and may not be installed at the desired position on the electrodes 21 and 22. The dielectrophoretic force F1 applied to the light-emitting element 30 may be insufficient to place both ends of the light-emitting element 30 on the first electrode 21 and the second electrode 22, and the light-emitting element 30 may be placed so that its extension direction is inclined with respect to the direction in which the electrodes 21 and 22 are located.

[0416] Furthermore, even if the element solvent 103 and the photodegradable thickener 500 are removed in a subsequent process, the orientation direction or alignment state of the light emitting element 30 may change, or the element solvent 103 may not be completely removed due to the viscosity of the light emitting element ink 1001 .

[0417] refer to Figure 35 , when the element solvent 103 and the photodegradable thickener 500 are removed after the light emitting element 30 is placed on the electrodes 21 and 22, the initial alignment state of the light emitting element 30 (at Figure 35 The photodegradable thickener 500 and the light emitting element 30 may be attracted by the attraction force due to the fluid flow or the attraction force Fa between the photodegradable thickener 500 and the light emitting element 30 (see FIG. Figure 35 Therefore, as described above, the acute angle θi formed by the direction in which the light emitting element 30 finally placed on the electrodes 21 and 22 extends and the direction perpendicular to the direction in which the electrodes 21 and 22 extend can have a large value.

[0418] Furthermore, in the light-emitting element ink 1001 having high viscosity, the element solvent 103 and the photodegradable thickener 500 may not be completely removed and may remain as foreign matter in subsequent processes. Foreign matter remaining on the electrodes 21 and 22 and the light-emitting element 30 may cause contact failure with the light-emitting element 30 in the subsequent process of forming the contact electrode 26. If a high-temperature heat treatment process is performed to completely remove them, the light-emitting element 30 and circuit elements included in the target substrate SUB may be damaged.

[0419] The method for manufacturing the display device 10 according to the embodiment may include placing the light-emitting element 30 on the electrodes 21 and 22 or after placing the light-emitting element 30, irradiating light to the light-emitting element ink 1001. When light is irradiated to the light-emitting element ink 1001, the photodegradable functional group of each photodegradable thickener 500 can be decomposed to form a plurality of fragment molecules 500'. The light-emitting element ink 1001 can have a low viscosity, and the photodegradable thickener 500 does not form a 3D network structure even in a state where no shear stress is applied. Therefore, the light-emitting element 30 can be subjected to a dielectrophoretic force sufficient to place the light-emitting element 30 at a desired position on the electrodes 21 and 22, and in a subsequent process, the element solvent 103 and the photodegradable thickener 500 can be completely removed by a relatively low-temperature heat treatment process.

[0420] Figures 36 to 38 is a schematic diagram illustrating a process of placing a light emitting element on an electrode during a process of manufacturing a display device according to the embodiment. Figure 36 An operation of irradiating light to the light emitting element ink 1001 is illustrated, and Figure 37 and Figure 38 An operation of placing the light emitting element 30 by generating an electric field on the target substrate SUB is exemplified.

[0421] First, refer to Figure 36, the process of manufacturing the display device 10 according to the embodiment may include irradiating light UV to the light-emitting element ink 1001 sprayed on the target substrate SUB. When the light UV is irradiated to the light-emitting element ink 1001, the bond of the photodegradable functional group of each photodegradable thickener 500 may be decomposed to form a plurality of fragment molecules 500'. The fragment molecules 500' may have a smaller molecular weight than the photodegradable thickener 500, and even if intermolecular hydrogen bonds are formed, the light-emitting element ink 1001 may have a low viscosity. When the electric field EL is generated on the target substrate SUB in a subsequent process, the light-emitting element 30 may be placed on the electrodes 21 and 22 in a state in which the light-emitting element 30 is dispersed in the light-emitting element ink 1001 having a low viscosity.

[0422] Then, refer to Figure 37 and Figure 38 , the light emitting element 30 is placed on the electrodes 21 and 22 by generating an electric field EL on the target substrate SUB. Since the light emitting element ink 1001 has a low viscosity, the light emitting element 30 can be subjected to a dielectrophoretic force F2 sufficient to place the light emitting element 30 at a desired position. As the position and orientation direction of the light emitting element 30 change from the initial scattered position (at Figure 38 The alignment of the light-emitting element 30 may be changed by changing the alignment direction of the light-emitting element 30 (indicated by dotted lines in the figure), and the two end portions of the light-emitting element 30 may be placed on the first electrode 21 and the second electrode 22, respectively. The light-emitting element 30 may be placed on each electrode 21 or 22 with a relatively uniform alignment. The "alignment" of the light-emitting element 30 may refer to a deviation between the orientation direction of the light-emitting element 30 aligned on the target substrate SUB and the mounting position. For example, when the deviation between the orientation direction of the light-emitting element 30 and the mounting position is large, it can be understood that the alignment of the light-emitting element 30 is low. When the deviation between the orientation direction of the light-emitting element 30 and the mounting position is small, it can be understood that the alignment of the light-emitting element 30 is high.

[0423] Then, the element solvent 103 and the photodegradable thickener 500 or the fragment molecules 500 ′ of the light emitting element ink 1001 are removed.

[0424] As described above, the process of removing the element solvent 103 and the photodegradable thickener 500 or the fragment molecules 500' can be performed through a conventional heat treatment process. The photodegradable thickener 500 can form fragment molecules 500' having a small molecular weight due to the decomposition of the bonds of its photodegradable functional groups, and can be completely removed even through a relatively low-temperature heat treatment process. In an embodiment, the heat treatment process can be performed at a temperature in the range of 200°C to 400°C or about 300°C. When the heat treatment process is performed within the above range, the element solvent 103, the photodegradable thickener 500, and the fragment molecules 500' can be completely removed while preventing damage to the light-emitting element 30 and the circuit elements.

[0425] In a state where the light-emitting elements 30 are dispersed in the light-emitting element ink 1001 having low viscosity, the light-emitting elements 30 can be placed on the electrodes 21 and 22 with a high degree of alignment. Even if the element solvent 103, the photodegradable thickener 500, and the fragment molecules 500' are removed by a heat treatment process, the light-emitting elements 30 can maintain their initial alignment state in the light-emitting element ink 1001. Therefore, as described above, the acute angle θi formed by the direction in which the light-emitting elements 30 finally placed on the electrodes 21 and 22 extend and the direction perpendicular to the direction in which the electrodes 21 and 22 extend can have a very small value.

[0426] Then, a plurality of insulating layers and contact electrodes 26 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. According to the embodiment, the display device 10 having the light emitting element 30 disposed on the electrodes 21 and 22 may be manufactured using the light emitting element ink 1001 containing the light emitting element 30 and the photodegradable thickener 500. The process of manufacturing the display device 10 may include a process of ejecting the light emitting element ink 1001 onto the target substrate SUB and irradiating light to the light emitting element ink 1001. The light emitting element ink 1001 may have a viscosity required for each process, and the light emitting element 30 may be placed on the electrodes 21 and 22 with a high degree of alignment. Through the process of manufacturing the display device 10 according to the embodiment, the display device 10 having improved product reliability by including the light emitting element 30 may be manufactured.

[0427] Figure 39 is a cross-sectional view illustrating a portion of a method for manufacturing a display device according to the embodiment.

[0428] As described above, the operation of decomposing each photodegradable thickener 500 into a plurality of fragment molecules 500 ′ by irradiating light UV to the light emitting element ink 1001 and the operation of mounting the light emitting element 30 on the electrodes 21 and 22 by generating the electric field EL can be simultaneously performed in one process.

[0429] refer to Figure 39 , an alignment signal can be transmitted through electrodes 21 and 22 while UV light is irradiated onto light-emitting element ink 1001 ejected onto electrodes 21 and 22. Consequently, the photodegradable thickener 500 can be decomposed into fragment molecules 500', thereby reducing the viscosity of light-emitting element ink 1001. Simultaneously, light-emitting element 30 can be mounted on electrodes 21 and 22 by the electric field EL generated by transmitting the alignment signal to electrodes 21 and 22. Since the process of mounting light-emitting element 30 is performed while UV light is irradiated onto light-emitting element ink 1001, the process time can be shortened.

[0430] In addition, although not illustrated in the drawings, after the light-emitting element 30 is mounted, the process of removing the element solvent 103 and the photodegradable thickener 500 may be performed sequentially. In particular, when the operation of decomposing the photodegradable thickener 500 is performed by a heat treatment process, the light-emitting element 30 can be mounted on the electrodes 21 and 22 by transmitting an alignment signal to the electrodes 21 and 22 during the heat treatment process. Therefore, the efficiency of the process of manufacturing the display device 10 can be improved.

[0431] 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 preferred embodiments without departing substantially from the principles of the present invention. Therefore, the disclosed preferred embodiments of the present invention 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, the method comprising: ejecting a light emitting element ink including a first element solvent and a light emitting element dispersed in the first element solvent on a target substrate having a first electrode and a second electrode formed thereon; forming a second element solvent in which at least some bonds of the first element solvent are decomposed by irradiating light to the first element solvent, and mounting the light emitting element on the first electrode and the second electrode; and removing the second component solvent, wherein the first component solvent comprises a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with the light; and a first functional group and a second functional group bonded to the photodegradable functional group and represented by the following Chemical Formula 1, and The first component solvent is at least one of the compounds represented by the following Chemical Formula 2 to Chemical Formula 5: [Chemical Formula 1] ， in n is an integer from 1 to 5, the first functional group n value and the second functional group n The sum of the values ​​is 2 to 6, and R5 is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group, and [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] ， Wherein R1 and R2 are represented by chemical formula 1, R1 in chemical formula 1 n The value and R2 in the chemical formula 1 n The sum of the values ​​is 2 to 6, and Each of R3 and R4 is independently C1-C 10 Alkyl groups, C2-C 10 Alkenyl groups, C2-C 10 Alkynyl group, C1-C 10 Alkyl ether groups and C2-C 10 Any of the alkenyl ether groups.

2. The method of claim 1, wherein in forming the second component solvent, At least some bonds of the photodegradable functional group are decomposed by the irradiated light to form at least one photodegradable fragment, and The second component solvent comprises the photodegradable fragments. 3 . The method of claim 2 , wherein the photodegradable fragment is bonded to at least one of the first functional group and the second functional group.

4. The method of claim 2, wherein the molecular weight of the second component solvent is 50% or less than the molecular weight of the first component solvent.

5. The method of claim 4, wherein the first component solvent has a viscosity of 7 cp to 15 cp, and The second component solvent has a viscosity of 5 cp or less.

6. The method of claim 1 , wherein the installing of the light emitting element comprises: forming an electric field on the first electrode and the second electrode; as well as The electric field aligns the orientation direction of the light emitting element.

7. The method of claim 6, wherein the light emitting element extends in one direction, and An acute angle formed by a direction in which the light emitting element extends and a direction perpendicular to a direction in which the first electrode and the second electrode extend is 88 degrees to 90 degrees.

8. A light-emitting element solvent for dispersing semiconductor crystals, comprising: a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with light; and different first and second functional groups bonded to the photodegradable functional group, and The light-emitting element solvent is represented by the following formula 1: wherein the chemical bond of the photodegradable functional group is decomposed upon irradiation with the light to form at least one photodegradable fragment: [Formula 1] X1-P-X2, wherein P is a photodegradable functional group, X1 is a first functional group, and X2 is a second functional group, wherein the first functional group and the second functional group are represented by the following Chemical Formula 1, and The light-emitting element solvent is any one of the compounds represented by the following Chemical Formula 2 to Chemical Formula 5: [Chemical Formula 1] ， in n is an integer from 1 to 5, the first functional group n value and the second functional group n The sum of the values ​​is 2 to 6, and R5 is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group, and [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] ， Wherein R1 and R2 are represented by chemical formula 1, R1 in chemical formula 1 n The value and R2 in the chemical formula 1 n The sum of the values ​​is 2 to 6, and Each of R3 and R4 is independently C1-C 10 Alkyl groups, C2-C 10 Alkenyl groups, C2-C 10 Alkynyl group, C1-C 10 Alkyl ether groups and C2-C 10 Any of the alkenyl ether groups.

9. The light-emitting element solvent according to claim 8, which is a compound represented by the following Chemical Formula 6: [Chemical Formula 6] 。 10. The light-emitting element solvent according to claim 8, which forms a first element solvent represented by the above formula 1, wherein when irradiated with said light, said first element solvent forms a second element solvent comprising said photodegradable fragments. 11 . The light-emitting element solvent according to claim 10 , wherein the photodegradable fragment is bonded to at least one of the first functional group and the second functional group.

12. The light-emitting element solvent according to claim 10, wherein the molecular weight of the second element solvent is 50% or less of the molecular weight of the first element solvent.

13. The light-emitting element solvent according to claim 12, wherein the first element solvent has a viscosity of 7 cp to 15 cp, and The second component solvent has a viscosity of 5 cp or less.

14. Luminescent element ink, comprising: a light emitting element including a semiconductor crystal and an insulating film surrounding an outer peripheral surface of the semiconductor crystal; and a light-emitting element solvent in which one or more light-emitting elements are dispersed, wherein the light-emitting element solvent comprises a photodegradable functional group in which at least one chemical bond is decomposed when irradiated with light; and a first functional group and a second functional group bonded to the photodegradable functional group and represented by the following Chemical Formula 1, and The light-emitting element solvent is any one of the compounds represented by the following Chemical Formula 2 to Chemical Formula 5: [Chemical Formula 1] ， in n is an integer from 1 to 5, the first functional group n value and the second functional group n The sum of the values ​​is 2 to 6, and R5 is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group, and [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] ， Wherein R1 and R2 are represented by chemical formula 1, R1 in chemical formula 1 n The value and R2 in the chemical formula 1 n The sum of the values ​​is 2 to 6, and Each of R3 and R4 is independently C1-C 10 Alkyl groups, C2-C 10 Alkenyl groups, C2-C 10 Alkynyl group, C1-C 10 Alkyl ether groups and C2-C 10 Any of the alkenyl ether groups.

15. The light-emitting element ink according to claim 14, wherein the light-emitting element solvent is a compound represented by the following Chemical Formula 6: [Chemical Formula 6] 。 16. The light-emitting element ink according to claim 14, wherein the chemical bond of the photodegradable functional group of the light-emitting element solvent is decomposed when irradiated with the light to form at least one photodegradable fragment, and The photodegradable fragment is bonded to at least one of the first functional group and the second functional group. 17 . The light-emitting element ink according to claim 16 , wherein the viscosity of the light-emitting element solvent decreases because the chemical bond of the photodegradable functional group is decomposed by the irradiated light.

18. The light-emitting element ink according to claim 17, wherein the semiconductor crystal comprises: a first semiconductor layer doped with a first conductivity type; a second semiconductor layer doped with a second conductivity type having a different polarity than the first conductivity type; as well as An active layer is formed between the first semiconductor layer and the second semiconductor layer.

19. A method for manufacturing a display device, the method comprising: preparing a light-emitting element ink comprising a solvent, a plurality of light-emitting elements dispersed in the solvent, and a photodegradable thickener; ejecting the light emitting element ink onto a target substrate on which a first electrode and a second electrode are formed; as well as irradiating light to the light emitting element ink and mounting the light emitting element on the first electrode and the second electrode, wherein each of the photodegradable thickeners comprises a third functional group including a functional group capable of forming a hydrogen bond and a photodegradable functional group bonded to the third functional group and wherein the bond is decomposed when irradiated with the light, and is represented by any one of the following Formulae 2 to 5: [Formula 2] [Formula 3] [Formula 4] [Formula 5] ， wherein "HP1" and "HP2" are third functional groups, "HP1" is any one of a secondary amine group, an amide group, a urea group, and a carbamate group, and "HP2" is a hydroxyl group or a primary amine group, "CP" is a photodegradable functional group, "R6" is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group, "R7" is any one of an acryloyl group, a methacryloyl group, an ester group, and a carbonate group, m is an integer from 1 to 3, and l An integer from 10 to 100.

20. The method of claim 19, wherein each of the photodegradable thickeners is represented by any one of the following Chemical Formulas 7 to 11: [Chemical Formula 7] [Chemical Formula 8] [Chemical Formula 9] [Chemical Formula 10] [Chemical Formula 11] ， in l An integer from 10 to 100. 21 . The method according to claim 19 , wherein in the preparation of the light-emitting element ink, the photodegradable thickener forms a network structure because the third functional group forms an intermolecular hydrogen bond.

22. The method of claim 21, wherein the light emitting element ink has a viscosity of 30 cP to 70 cP when no shear stress is applied. 23 . The method according to claim 19 , wherein in the ejecting of the light emitting element ink, the hydrogen bond of the third functional group in each of the photodegradable thickeners is decomposed. 24 . The method of claim 23 , wherein the light emitting element ink has a viscosity of 5 cP to 15 cP when no shear stress is applied. 25 . The method of claim 19 , wherein each of the photodegradable thickeners forms a plurality of fragment molecules because the photodegradable functional groups are decomposed when irradiated with the light.

26. The method of claim 25, wherein said installing of said light emitting element comprises: forming an electric field on the first electrode and the second electrode; aligning the orientation direction of the light emitting element by the electric field; as well as The solvent and the fragment molecules are removed.

27. The method of claim 26, wherein the removing of the solvent and the fragment molecules is performed by a heat treatment process at 200°C to 400°C.

28. The method of claim 25, wherein the light emitting element extends in one direction, and An acute angle formed by a direction in which the light emitting element extends and a direction in which the first electrode and the second electrode extend is 88 degrees to 90 degrees.

29. Luminescent element ink, comprising: solvents; light-emitting elements dispersed in the solvent and each including a plurality of semiconductor layers and an insulating film partially surrounding outer surfaces of the semiconductor layers; and a photodegradable thickener dispersed in the solvent, wherein each of the photodegradable thickeners comprises a third functional group including a functional group capable of forming a hydrogen bond and a photodegradable functional group bonded to the third functional group and wherein the bond is decomposed when irradiated with light, and The photodegradable thickener is represented by any one of the following Formulas 2 to 5: [Formula 2] [Formula 3] [Formula 4] [Formula 5] ， wherein "HP1" and "HP2" are third functional groups, "HP1" is any one of a secondary amine group, an amide group, a urea group, and a carbamate group, and "HP2" is a hydroxyl group or a primary amine group, "CP" is a photodegradable functional group, "R6" is any one of a C1-C5 alkyl group, a C2-C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group, and a C2-C5 alkenyl ether group, "R7" is any one of an acryloyl group, a methacryloyl group, an ester group, and a carbonate group, m is an integer from 1 to 3, and l An integer from 10 to 100. 30 . The light emitting element ink according to claim 29 , wherein the photodegradable functional group includes any one of a cyclobutyl group, a maleimide dimer, an acrylate dimer, and a carbonyl group.

31. The light-emitting element ink according to claim 30, wherein each of the photodegradable thickeners is represented by any one of the following Chemical Formulas 7 to 11: [Chemical Formula 7] [Chemical Formula 8] [Chemical Formula 9] [Chemical Formula 10] [Chemical Formula 11] ， in l An integer from 10 to 100. 32 . The light-emitting element ink according to claim 29 , wherein when no shear stress is applied, the photodegradable thickener forms a network structure because the third functional group forms an intermolecular hydrogen bond. 33 . The light-emitting element ink according to claim 32 , which has a viscosity of 30 cP to 70 cP when no shear stress is applied. 34 . The light-emitting element ink according to claim 29 , wherein when shear stress is applied, an intermolecular hydrogen bond of the third functional group of the photodegradable thickener is decomposed. 35 . The light-emitting element ink according to claim 34 , which has a viscosity of 5 cP to 15 cP when shear stress is applied.

36. The light-emitting element ink according to claim 29, wherein the semiconductor layer of each of the light-emitting elements includes a first semiconductor layer, a second semiconductor layer, and an active layer provided between the first semiconductor layer and the second semiconductor layer, and The insulating film surrounds at least an outer surface of the active layer.

37. Photodegradable thickener comprising: a third functional group comprising a functional group capable of forming a hydrogen bond; and a photodegradable functional group bonded to the third functional group and wherein the bond is decomposed when irradiated with light, the photodegradable thickener being represented by any one of the following Formulae 2 to 5: [Formula 2] [Formula 3] [Formula 4] [Formula 5] ， wherein "HP1" and "HP2" are third functional groups, "HP1" is any one of a secondary amine group, an amide group, a urea group, and a carbamate group, and "HP2" is a hydroxyl group or a primary amine group, "CP" is a photodegradable functional group, "R6" is a C1-C5 alkyl group, C 2- Any one of a C5 alkenyl group, a C2-C5 alkynyl group, a C1-C5 alkyl ether group and a C2-C5 alkenyl ether group, "R7" is any one of an acryloyl group, a methacryloyl group, an ester group, and a carbonate group, m is an integer from 1 to 3, and l An integer from 10 to 100.

38. The photodegradable thickener according to claim 37, wherein the photodegradable functional group comprises any one of a cyclobutyl group, a maleimide dimer, an acrylate dimer, and a carbonyl group.

39. The photodegradable thickener according to claim 38, which is represented by any one of the following Chemical Formulas 7 to 11: [Chemical Formula 7] [Chemical Formula 8] [Chemical Formula 9] [Chemical Formula 10] [Chemical Formula 11] ， in l An integer from 10 to 100.

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