LIGHT-EMITTING ELEMENT, DISPLAY APPARATUS, AND MANUFACTURING METHOD THEREFOR

A light-emitting element includes a first semiconductor layer doped to have a first polarity; a second semiconductor layer doped to have a second polarity that is different from the first polarity; an active layer placed between the first semiconductor layer and the second semiconductor layer; and an insulating layer surrounding at least the outer surface of the active material. The insulating layer includes an insulating film surrounding the active layer, and an element dispersion agent including a magnetic metal and bonded to an outer surface of the insulating film.

BACKGROUND

1. Technical Field

The invention relates to a light-emitting element, a display device, and a manufacturing method therefor.

2. Description of Related Art

The importance of display devices has steadily increased with the development of multimedia technology. In response thereto, various types of display devices such as an organic light emitting display (OLED), a liquid crystal display (LCD) and the like have been used.

A display device is a device for displaying an image, and includes a display panel, such as an organic light emitting display panel or a liquid crystal display panel. The light emitting display panel may include light emitting elements, e.g., light emitting diodes (LED), and examples of the light emitting diode include an organic light emitting diode (OLED) using an organic material as a fluorescent material and an inorganic light emitting diode using an inorganic material as a fluorescent material.

SUMMARY

Aspects of the disclosure provide a light-emitting element having an element dispersion agent, which includes a magnetic metal, bonded to an outer surface thereof.

Aspects of the disclosure also provide a display device including the light-emitting element and a manufacturing method therefor.

It should be noted that aspects of the disclosure are not limited thereto and other aspects, which are not mentioned herein, will be apparent to those of ordinary skill in the art from the following description.

According to an embodiment of the disclosure, a light-emitting element, comprises a first semiconductor layer doped with a first polarity, a second semiconductor layer doped with a second polarity different from the first polarity, an active layer disposed between the first semiconductor layer and the second semiconductor layer, and an insulating layer surrounding at least an outer surface of the active layer, wherein the insulating layer includes an insulating film surrounding the active layer and an element dispersion agent including a magnetic metal and bonded to an outer surface of the insulating film.

The element dispersion agent may include a ligand forming a coordination bond with the magnetic metal and a first functional group bonded to the ligand.

The ligand may be one of a porphyrin structure and a multi-dentate structure, and the magnetic metal may be one of Fe, Co, Ni, Mn, and Cr.

The first functional group may form a chemical bond with the insulating film.

The first functional group may be at least one of a silane group, a boronate group, a carboxylic acid group, an amine group, a thiol group, and a phosphoric acid group.

The element dispersion agent may further include at least one second functional group including a hydrophobic functional group and bonded to the ligand.

The at least one second functional group may include at least one of an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 3 to 6 carbon atoms.

The element dispersion agent may have a structure represented by one of Chemical Formulas A to D below,

wherein M is at least one of Fe2+, Mn2+, CO2+, Ni2+, and Cr2+, R1is at least one of a silane group, a boronate group, a carboxylic acid group, an amine group, a thiol group, and a phosphoric acid group, each of R2to R4is independently one of hydrogen, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, and a cycloalkyl group having 3 to 6 carbon atoms, n is an integer of 1 to 6, and a dash line indicates a coordination bond.

According to an embodiment of the disclosure, a display device comprises a first electrode, and a second electrode that is spaced apart from and faces the first electrode, and a light-emitting element disposed between the first electrode and the second electrode, wherein the light-emitting element includes: a first semiconductor layer doped with a first polarity, a second semiconductor layer doped with a second polarity different from the first polarity, an active layer disposed between the first semiconductor layer and the second semiconductor layer, and an insulating layer surrounding at least an outer surface of the active layer. The insulating layer includes an insulating film and an element dispersion agent including a magnetic metal and bonded to an outer surface of the insulating film.

The element dispersion agent may include a ligand forming a coordination bond with the magnetic metal, a first functional group bonded to the ligand to form a chemical bond with the insulating film, and at least one second functional group including a hydrophobic functional group and bonded to the ligand.

The element dispersion agent may have a structure represented by one of the Chemical Formulas A to D above.

The display device may further comprise a first insulating layer disposed between the first electrode and the second electrode and covering at least a portion of each of the first electrode and the second electrode, and a second insulating layer disposed on the first insulating layer between the first electrode and the second electrode, wherein the light-emitting element may be disposed on the first insulating layer and the second insulating layer.

The element dispersion agent of the light-emitting element may directly contact with the first insulating layer and the second insulating layer.

According to an embodiment of the disclosure, a method of manufacturing a display device, the method comprises preparing an ink in which light-emitting elements each including a semiconductor core and an insulating layer surrounding the semiconductor core are dispersed, and applying a magnetic field to the light-emitting elements, preparing a target substrate on which a first electrode and a second electrode spaced apart from each other are formed, and spraying the ink in which the light-emitting elements are dispersed onto the target substrate, and disposing the light-emitting elements between the first electrode and the second electrode by generating an electric field on the target substrate.

The semiconductor core may include a first semiconductor layer doped with a first polarity, a second semiconductor layer doped with a second polarity different from the first polarity, an active layer disposed between the first semiconductor layer and the second semiconductor layer, and an insulating layer surrounding at least an outer surface of the active layer, wherein the insulating layer may include an insulating film and an element dispersion agent including a magnetic metal and bonded to an outer surface of the insulating film.

The method may further comprise applying a magnetic force to the magnetic metal of the element dispersion agent by the magnetic field. In the applying of the magnetic field, the magnetic force may be transmitted to the light-emitting elements in a direction opposite to a gravity direction.

The ink may be sprayed onto the target substrate in a state in which the magnetic field is applied.

In the disposing of the light-emitting elements by the electric field, one end portion of each of the light-emitting elements may be disposed on the first electrode and the other end portion thereof is disposed on the second electrode.

The element dispersion agent may include a ligand forming a coordination bond with the magnetic metal, a first functional group bonded to the ligand to form a chemical bond with the insulating film, and at least one second functional group including a hydrophobic functional group and bonded to the ligand.

The element dispersion agent may have a structure represented by one of the Chemical Formulas A to D above.

A light-emitting element according to an embodiment includes a semiconductor core and an insulating layer surrounding the semiconductor core, and the insulating layer includes an insulating film and an element dispersion agent bonded to an outer surface of the insulating film. The element dispersion agent includes a magnetic metal and a ligand capable of forming a coordination bond with the magnetic metal. A magnetic force can be applied to the magnetic metal by a magnetic field, and the magnetic force received by the magnetic metal can be transmitted to the light-emitting element, and thus a rate at which the light-emitting element is precipitated in an ink can be reduced.

Accordingly, during a manufacturing process of a display device including the light-emitting element, the light-emitting elements can be sprayed by an inkjet printing process in a state in which the light-emitting elements are uniformly dispersed in the ink, and the sprayed ink can include a uniform number of light-emitting elements.

Further, in a display device according to an embodiment, a uniform number of light-emitting elements can be disposed for each pixel by the above-described manufacturing process.

The effects according to the embodiments are not limited by the contents exemplified above, and more various effects are included in this disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG.1is a schematic plan view of a display device according to an embodiment.

Referring toFIG.1, a display device10displays a video or a still image. The display device10may refer to all electronic devices that provide a display screen. For example, the display device10may include a television, a notebook (or laptop), a monitor, an advertising board, an Internet of Things (IoT) device, 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 organizer, an electronic-book reader, a portable multimedia player (PMP), a navigation device, a game machine, a digital camera, a camcorder, and the like, which provide a display screen.

The display device10includes a display panel that displays an image. Examples of the display panel may include an inorganic light-emitting diode (LED) display panel, an organic light-emitting display panel, a quantum dot light-emitting display panel, a plasma display panel, a field emission display panel, and the like. Hereinafter, although an example in which the inorganic LED display panel as an example of the display panel is applied is described, the disclosure is not limited thereto, and in case that the same technical spirit is applicable thereto, it may be applied to other display panels.

A shape of the display device10may be variously modified. For example, the display device10may have shapes such as a rectangular shape of which lateral sides are long, a rectangular shape of which longitudinal sides are long, a square shape, a quadrangular shape of which corner portions (vertexes) are round, other polygonal shapes, a circular shape, and the like. A shape of a display area DPA of the display device10may also be similar to the overall shape of the display device10.FIG.1illustrates the display device10and the display area DPA which have a rectangular shape of which lateral sides are long.

The display device10may include the display area DPA and a non-display area NDA. The display area DPA is an area in which an image may be displayed, and the non-display area NDA is an area in which an image is not displayed. The display area DPA may refer to an active area and the non-display area NDA may refer to an inactive area. The display area DPA may generally occupy a center of the display device10.

The display area DPA may include pixels PX. The pixels PX may be disposed in a matrix shape. A shape of each of the pixels PX may be a rectangular shape or a square shape in a plan view, but the disclosure is not limited thereto, and the shape may be a rhombic shape of which each side is inclined with respect to a direction. The pixels PX may be alternately disposed in a stripe type or a PenTile® type. In addition, each of the pixels PX may include one or more light-emitting elements300that emit light in a specific wavelength range, thereby displaying a specific color.

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 has a rectangular shape, 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 bezel of the display device10. In each non-display area NDA, lines or circuit driving parts included in the display device10may be disposed, or external devices may be mounted.

FIG.2is a schematic plan view illustrating a pixel of the display device according to an embodiment.FIG.3is a schematic cross-sectional view taken along line III-III′ ofFIG.2.

Referring toFIG.2, each of the pixels PX may include a first sub-pixel PX1, a second sub-pixel PX2, and a third sub-pixel PX3. The first sub-pixel PX1may emit light of a first color, the second sub-pixel PX2may emit light of a second color, and the third sub-pixel PX3may 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 disclosure is not limited thereto, and the sub-pixels PXn may emit light having a same color, where n is a natural number. In addition,FIG.2illustrates that the pixel PX includes three sub-pixels PXn, but the disclosure is not limited thereto, and the pixel PX may also include a larger number of sub-pixels PXn.

Each of the sub-pixels PXn of the display device10may include an area defined as a light-emitting area EMA. The first sub-pixel PX1may include a first light-emitting area EMA1, the second sub-pixel PX2may include a second light-emitting area EMA2, and the third sub-pixel PX3may include a third light-emitting area EMA3. The light-emitting area EMA may be defined as an area in which the light-emitting element300included in the display device10is disposed to emit light in a specific wavelength range. The light-emitting element300includes an active layer330(seeFIG.4), and the active layer330may emit light in a specific wavelength range without directivity. The light emitted from the active layer330of the light-emitting element300may also be emitted in directions toward side surfaces of the light-emitting element300including ends. The light-emitting area EMA may include an area in which the light-emitting element300is disposed, and may include an area which is adjacent to the light-emitting element300and through which the light emitted from the light-emitting element300is emitted.

However, the disclosure is not limited thereto, and the light-emitting area EMA may also include an area in which light emitted from the light-emitting element300is reflected or refracted by another member to be emitted. Light-emitting elements300may be disposed in each sub-pixel PXn, and the area in which the light-emitting elements300are disposed and an area adjacent to the area form the light-emitting area EMA.

Although not shown in the drawing, each of the sub-pixels PXn of the display device10may include a non-light-emitting area which is defined as an area except for the light-emitting area EMA. The non-light-emitting area may be an area in which the light-emitting elements300are not disposed and which light emitted from the light-emitting elements300does not reach so that light is not emitted.

FIG.3illustrates only a cross section of the first sub-pixel PX1ofFIG.2, but the cross section may be identically applied to other pixels PX or sub-pixels PXn.FIG.3illustrates a cross section traversing from a first end portion (or one end portion) to a second end portion (or the other end portion) of the light-emitting element300disposed in the first sub-pixel PX1ofFIG.2.

Referring toFIG.3in conjunction withFIG.2, the display device10may include a circuit element layer and a display element layer disposed on a first substrate101. A semiconductor layer, conductive layers, and insulating layers are disposed on the first substrate101, each of which may form the circuit element layer and the display element layer. The conductive layers may include a first gate conductive layer, a second gate conductive layer, a first data conductive layer, and a second data conductive layer disposed below a first planarization layer109to form the circuit element layer, and electrodes210and220and contact electrodes260disposed on the first planarization layer109to form the display element layer. The insulating layers may include a buffer layer102, a first gate insulating layer103, a first protective layer105, a first interlayer insulating layer107, a second interlayer insulating layer108, the first planarization layer109, a first insulating layer510, a second insulating layer520, a third insulating layer530, a fourth insulating layer550, and the like.

The circuit element layer may include circuit elements and lines for driving the light-emitting element300, such as a driving transistor DT, a switching transistor ST, a first conductive pattern CDP, and voltage lines VDL and VSL, and the display element layer may include the light-emitting element300and include a first electrode210, a second electrode220, a first contact electrode261, a second contact electrode262, and the like.

The first substrate101may be an insulating substrate. The first substrate101may be made of an insulating material such as glass, quartz, a polymer resin, or the like. In addition, the first substrate101may be a rigid substrate but may also be a flexible substrate that is bendable, foldable, rollable, or the like.

Light-blocking layers BML1and BML2may be disposed on the first substrate101. The light-blocking layers BML1and BML2may include a first light-blocking layer BML1and a second light-blocking layer BML2. The first light-blocking layer BML1and the second light-blocking layer BML2are disposed to at least respectively overlap a first active layer (or first active material layer) DT_ACT of the driving transistor DT and a second active layer (or second active material layer) ST_ACT of the switching transistor ST. The light-blocking layers BML1and BML2may include light-blocking materials to prevent light from being incident on the first and second active layers DT_ACT and ST_ACT. As an example, the first and second light-blocking layers BML1and BML2may be made of opaque metal materials that block light from being transmitted. However, the disclosure is not limited thereto, and in some embodiments, the light-blocking layers BML1and BML2may be omitted. Although not shown in the drawing, the first light-blocking layer BML1may be electrically connected to a first source/drain electrode DT_SD1of the driving transistor DT, which will be described below, and the second light-blocking layer BML2may be electrically connected to a first source/drain electrode ST_SD1of the switching transistor ST.

The buffer layer102may be disposed entirely on the light-blocking layers BML1and BML2and the first substrate101. The buffer layer102may be formed on the first substrate101to protect the driving and switching transistors DT and ST of the pixel PX from moisture permeating through the first substrate101that is vulnerable to moisture permeation, and may perform a surface planarization function. The buffer layer102may be formed as inorganic layers that are alternately stacked. For example, the buffer layer102may be formed as multiple layers in which inorganic layers including at least one of silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON) are alternately stacked.

The semiconductor layer is disposed on the buffer layer102. The semiconductor layer may include the first active layer DT_ACT of the driving transistor DT and the second active layer ST_ACT of the switching transistor ST. The first active layer DT_ACT and the second active layer ST_ACT may be disposed to partially overlap gate electrodes DT_G and ST_G or the like of a first gate conductive layer to be described below.

In an embodiment, the semiconductor layer may include polycrystalline silicon, monocrystalline silicon, an oxide semiconductor, and the like. The polycrystalline silicon may be formed by crystallizing amorphous silicon. Examples of the crystallization method may include a rapid thermal annealing (RTA) method, a solid phase crystallization (SPC) method, an excimer laser annealing (ELA) method, a metal induced lateral crystallization (MILC) method, and a sequential lateral solidification (SLS) method, and the like, but the disclosure is not limited thereto. In case that the semiconductor layer includes polycrystalline silicon, the first active layer DT_ACT may include a first doped area DT_ACTa, a second doped area DT_ACTb, and a first channel area DT_ACTc. The first channel area DT_ACTc may be disposed between the first doped area DT_ACTa and the second doped area DT_ACTb. The second active layer ST_ACT may include a third doped area ST_ACTa, a fourth doped area ST_ACTb, and a second channel area ST_ACTc. The second channel area ST_ACTc may be disposed between the third doped area ST_ACTa and the fourth doped area ST_ACTb. The first doped area DT_ACTa, the second doped area DT_ACTb, the third doped area ST_ACTa, and the fourth doped area ST_ACTb may be areas in which partial areas of the first active layer DT_ACT and the second active layer ST_ACT are doped with impurities.

In an embodiment, the first active layer DT_ACT and the second active layer ST_ACT may include an oxide semiconductor. In this case, the doped area of each of the first active layer DT_ACT and the second active layer ST_ACT may be an area that has become conductive. The oxide semiconductor may be an oxide semiconductor including indium (In). In some embodiments, the oxide semiconductor may include indium-tin oxide (ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-zinc-tin oxide (IZTO), indium-gallium-tin oxide (IGTO), indium-gallium-zinc-tin oxide (IGZTO), or the like. However, the disclosure is not limited thereto.

The first gate insulating layer103is disposed on the semiconductor layer and the buffer layer102. The first gate insulating layer103may be disposed on the buffer layer102, including the semiconductor layer. The first gate insulating layer103may serve as gate insulating layers of the driving transistor DT and the switching transistor ST. The first gate insulating layer103may be formed as an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), or as a stacked structure thereof.

The first gate conductive layer is disposed on the first gate insulating layer103. The first gate conductive layer may include a first gate electrode DT_G of the driving transistor DT and a second gate electrode ST_G of the switching transistor ST. The first gate electrode DT_G is disposed to overlap at least a partial area of the first active layer DT_ACT, and the second gate electrode ST_G is disposed to overlap at least a partial area of the second active layer ST_ACT. For example, the first gate electrode DT_G may be disposed to overlap the first channel area DT_ACTc of the first active layer DT_ACT in a thickness direction, and the second gate electrode ST_G may be disposed to overlap the second channel area ST_ACTc of the second active layer ST_ACT in the thickness direction.

The first gate conductive layer may be formed as a single layer or a multi-layer that is made of one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or an alloy thereof. However, the disclosure is not limited thereto.

The first protective layer105is disposed on the first gate conductive layer. The first protective layer105may be disposed to cover the first gate conductive layer and may perform a function of protecting the first gate conductive layer. The first protective layer105may be formed as an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), or as a stacked structure thereof.

A second gate conductive layer is disposed on the first protective layer105. The second gate conductive layer may include a first capacitor electrode CE1of a storage capacitor disposed so that at least a partial area thereof overlaps the first gate electrode DT_G in the thickness direction. The first capacitor electrode CE1and the first gate electrode DT_G may overlap each other in the thickness direction with the first protective layer105interposed therebetween, and the storage capacitor may be formed therebetween. The second gate conductive layer may be formed as a single layer or a multi-layer that is made of one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or an alloy thereof. However, the disclosure is not limited thereto.

The first interlayer insulating layer107is disposed on the second gate conductive layer. The first interlayer insulating layer107may serve as an insulating layer between the second gate conductive layer and other layers disposed thereon. The first interlayer insulating layer107may be formed as an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), or as a stacked structure thereof.

The first data conductive layer is disposed on the first interlayer insulating layer107. The first gate conductive layer may include the first source/drain electrode DT_SD1and a second source/drain electrode DT_SD2of the driving transistor DT, and the first source/drain electrode ST_SD1and a second source/drain electrode ST_SD2of the switching transistor ST.

The first source/drain electrode DT_SD1and the second source/drain electrode DT_SD2of the driving transistor DT may respectively contact the first doped area DT_ACTa and the second doped area DT_ACTb of the first active layer DT_ACT through contact holes passing through the first interlayer insulating layer107and the first gate insulating layer103. The first source/drain electrode ST_SD1and the second source/drain electrode ST_SD2of the switching transistor ST may respectively contact the third doped area ST_ACTa and the fourth doped area ST_ACTb of the second active layer ST_ACT through contact holes passing through the first interlayer insulating layer107and the first gate insulating layer103. In addition, the first source/drain electrode DT_SD1of the driving transistor DT and the first source/drain electrode ST_SD1of the switching transistor ST may be electrically connected to the first light-blocking layer BML1and the second light-blocking layer BML2, respectively, through other contact holes. For the first source/drain electrodes DT_SD1and ST_SD1and the second source/drain electrodes DT_SD2and ST_SD2of the driving transistor DT and the switching transistor ST, in case that one electrode is a source electrode, the other electrode may be a drain electrode. However, the disclosure is not limited thereto, and for the first source/drain electrodes DT_SD1and ST_SD1and the second source/drain electrodes DT_SD2and ST_SD2, in case that one electrode is a drain electrode, the other electrode may be a source electrode.

The first data conductive layer may be formed as a single layer or a multi-layer that is made of one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or an alloy thereof. However, the disclosure is not limited thereto.

The second interlayer insulating layer108may be disposed on the first data conductive layer. The second interlayer insulating layer108may be disposed entirely on the first interlayer insulating layer107while covering the first data conductive layer and may sever to protect the first data conductive layer. The second interlayer insulating layer108may be formed as an inorganic layer including an inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), and silicon oxynitride (SiON), or as a stacked structure thereof.

The second data conductive layer is disposed on the second interlayer insulating layer108. The second data conductive layer may include a second voltage line VSL, a first voltage line VDL, and the first conductive pattern CDP. A high-potential voltage (a first power voltage) to be supplied to the driving transistor DT may be applied to the first voltage line VDL, and a low-potential voltage (a second power voltage) to be supplied to the second electrode220may be applied to the second voltage line VSL. During the manufacturing process of the display device10, an alignment signal necessary to align the light-emitting element300may be applied to the second voltage line VSL.

The first conductive pattern CDP may be electrically connected to the first source/drain electrode DT_SD1of the driving transistor DT through a contact hole formed in the second interlayer insulating layer108. The first conductive pattern CDP may also contact the first electrode210, which will be described below, and the driving transistor DT may transmit the first power voltage applied from the first voltage line VDL, to the first electrode210through the first conductive pattern CDP.FIG.3illustrates that the second data conductive layer includes a first voltage line VDL and a second voltage line VSL, but the disclosure is not limited thereto. The second data conductive layer may include a larger number of first voltage lines VDL and a larger number of second voltage lines VSL.

The second data conductive layer may be formed as a single layer or a multi-layer that is made of one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or an alloy thereof. However, the disclosure is not limited thereto.

The first planarization layer109is disposed on the second data conductive layer. The first planarization layer109may include an organic insulating material, for example, an organic material such as polyimide (PI), and may perform a surface planarization function.

Inner banks410and420, electrodes210and220, an outer bank450, contact electrodes260, and the light-emitting element300are disposed on the first planarization layer109. Further, insulating layers510,520,530, and550may be further disposed on the first planarization layer109.

The inner banks410and420are disposed directly on the first planarization layer109. The inner banks410and420may include a first inner bank410and a second inner bank420disposed adjacent to a center portion of each pixel PX or sub-pixel PXn.

As shown inFIG.2, the first inner bank410and the second inner bank420may be disposed to be spaced apart from each other and face each other in a first direction DR1. In addition, the first inner bank410and the second inner bank420may extend in a second direction DR2, and may be spaced apart from each other and terminated at a boundary between the sub-pixels PXn so as not to extend to another sub-pixel PXn adjacent in the second direction DR2. Accordingly, the first inner bank410and the second inner bank420may be disposed in each sub-pixel PXn to form a pattern on the entire surface of the display device10. By disposing the inner banks410and420to be spaced apart from each other and face each other, an area in which the light-emitting element300is disposed may be formed therebetween.FIG.2illustrates that a first inner bank410and a second inner bank420are disposed, but the disclosure is not limited thereto. In some embodiments, multiple inner banks410and420may be disposed or larger numbers of inner banks410and420may be further disposed according to the numbers of the electrodes210and220, which will be described below.

Further, as shown inFIG.3, each of the first inner bank410and the second inner bank420may have a structure in which at least a portion thereof protrudes with respect to (or protrudes from) an upper surface of the first planarization layer109. The protruding portion of each of the first inner bank410and the second inner bank420may have inclined side surfaces, and light emitted from the light-emitting element300disposed between the first inner bank410and the second inner bank420may travel toward the inclined side surfaces of the inner banks410and420. As will be described below, in case that the electrodes210and220respectively disposed on the inner banks410and420include a material having a high reflectance, the light emitted from the light-emitting element300may be reflected from the side surfaces of the inner banks410and420to be emitted upward from the first substrate101. For example, the inner banks410and420may provide an area in which the light-emitting element300is disposed, and simultaneously may serve as a reflective partition wall that reflects the light emitted from the light-emitting element300upward. In an embodiment, the inner banks410and420may include an organic insulating material such as polyimide (PI), but the disclosure is not limited thereto.

The electrodes210and220are disposed on the inner banks410and420and the first planarization layer109. The electrodes210and220may include the first electrode210disposed on the first inner bank410and the second electrode220disposed on the second inner bank420.

As shown inFIG.2, the first electrode210may be disposed in each sub-pixel PXn in a form extending in the second direction DR2. However, the first electrode210may not extend to another sub-pixel PXn adjacent in the second direction DR2, and may be disposed to be partially spaced apart from the outer bank450surrounding each sub-pixel PXn. At least a partial area of the first electrode210is disposed to overlap the outer bank450, and the first electrode210may be electrically connected to the driving transistor DT in an area overlapping the outer bank450. For example, the first electrode210may contact the first conductive pattern CDP through a first contact hole CT1formed in an area overlapping the outer bank450, and passing through the first planarization layer109, and through this, the first electrode210may be electrically connected to the first source/drain electrode DT_SD1of the driving transistor DT.

The second electrode220may be disposed to extend in the second direction DR2in each sub-pixel PXn. Unlike the first electrode210, the second electrode220may be disposed to extend to another sub-pixel PXn adjacent to the sub-pixel PXn in the second direction DR2. For example, an electrically connected second electrode220may be disposed in the sub-pixels PXn adjacent to each other in the second direction DR2. The second electrode220may partially overlap the outer bank450at a boundary between the sub-pixels PXn adjacent to each other in the second direction DR2, and the second electrode220may be electrically connected to the second voltage line VSL in an area overlapping the outer bank450. For example, the second electrode220may contact the second voltage line VSL through a second contact hole CT2formed in an area overlapping the outer bank450, and passing through the first planarization layer109. As shown in the drawing, the second electrodes220of the sub-pixels PXn adjacent to each other in the first direction DR1are electrically connected to the second voltage lines VSL through the second contact holes CT2, respectively.

However, the disclosure is not limited thereto. In some embodiments, each of the first electrode210and the second electrode220may further include a stem portion extending in the first direction DR1. In the first electrode210, different stem portions may be disposed for each sub-pixel PXn, and in the second electrode220, a stem portion extends to the sub-pixels PXn adjacent to the sub-pixel PXn in the first direction DR1so that the second electrodes220of the sub-pixels PXn may be electrically connected to each other by the stem portion. In this case, the second electrode220may be electrically connected to the second voltage line VSL in the non-display area NDA located at a peripheral portion of the display area DPA in which the pixels PX or sub-pixels PXn are disposed.

FIG.2illustrates that a first electrode210and a second electrode220are disposed in each sub-pixel PXn, but the disclosure is not limited thereto. In some embodiments, larger numbers of first electrodes210and second electrodes220may be disposed in each sub-pixel PXn. In addition, the first electrode210and the second electrode220disposed in each sub-pixel PXn may not necessarily have a shape extending in one direction, and the first electrode210and the second electrode220may be disposed in various structures. For example, the first electrode210and the second electrode220may each have a partially curved or bent shape, and one of the first electrode210and the second electrode220may be disposed to surround the other thereof. As long as at least a partial area of each of the first electrode210and at least a partial area of the second electrode220are spaced apart from each other and face each other to form an area in which the light-emitting element300is to be disposed therebetween, the arrangement structures and shapes of the first electrode210and the second electrode220are not particularly limited.

The electrodes210and220may be electrically connected to the light-emitting elements300and may receive a voltage to allow the light-emitting element300to emit light. For example, the electrodes210and220may be electrically connected to the light-emitting element300through the contact electrodes260, which will be described below, and may transmit an electrical signal applied to the electrodes210and220to the light-emitting element300through the contact electrodes260.

In an embodiment, the first electrode210may be a pixel electrode separated for each sub-pixel PXn, and the second electrode220may be a common electrode electrically connected in common to each sub-pixel PXn. One of the first electrode210and the second electrode220may be an anode of the light-emitting element300, and the other thereof may be a cathode of the light-emitting element300. However, the disclosure is not limited thereto, and the reverse may be possible.

Further, each of the electrodes210and220may be utilized to form an electric field in the sub-pixel PXn, thereby aligning the light-emitting element300. The light-emitting element300may be disposed between the first electrode210and the second electrode220by a process of forming an electric field between the first electrode210and the second electrode220by applying an alignment signal to the first electrode210and the second electrode220. As will be described below, the light-emitting elements300may be sprayed onto the first electrode210and the second electrode220in a state of being dispersed in ink by an inkjet printing process, and may be aligned between the first electrode210and the second electrode220by a method of applying a dielectrophoretic force to the light-emitting elements300by applying the alignment signal between the first electrode210and the second electrode220.

As shown inFIG.3, the first electrode210and the second electrode220may be disposed on the first inner bank410and the second inner bank420, respectively, and may be spaced apart from each other and may face each other in the first direction DR1. The light-emitting elements300may be disposed between the first inner bank410and the second inner bank420, and the light-emitting element300may be disposed between the first electrode210and the second electrode220, and at least one first end portion of the light-emitting element300may be electrically connected to the first electrode210and the second electrode220.

In some embodiments, the first electrode210and the second electrode220may be formed to have greater widths than the first inner bank410and the second inner bank420, respectively. For example, the first electrode210and the second electrode220may be disposed to cover outer surfaces of the first inner bank410and the second inner bank420, respectively. The first electrode210and the second electrode220may be disposed on side surfaces of the first inner bank410and the second inner bank420, respectively, and a distance (or separation distance) between the first electrode210and the second electrode220may be less than a distance between the first inner bank410and the second inner bank420. In addition, at least a partial area of each of the first electrode210and the second electrode220may be disposed directly on the first planarization layer109.

Each of the electrodes210and220may include a transparent conductive material. As an example, each of the electrodes210and220may include materials such as indium tin oxide (ITO), indium zinc oxide (IZO), indium tin-zinc oxide (ITZO), and the like, but the disclosure is not limited thereto. In some embodiments, each of the electrodes210and220may include a conductive material having high reflectance. For example, each of the electrodes210and220may include a metal such as silver (Ag), copper (Cu), aluminum (Al), or the like as the material having high reflectance. In this case, each of the electrodes210and220may reflect light, which is emitted from the light-emitting element300and travels to the side surfaces of the first inner bank410and the second inner bank420, in an upward direction with respect to each sub-pixel PXn.

However, the disclosure is not limited thereto, and each of the electrodes210and220may be formed as a structure, in which one or more layers of a transparent conductive material and a metal layer having high reflectance are stacked, or formed as a single layer including the transparent conductive material and the metal layer. In an embodiment, each of the electrodes210and220may have a stacked structure of ITO/Ag/ITO/IZO or may be an alloy including Al, Ni, lanthanum (La), and the like.

The first insulating layer510is disposed on the first planarization layer109, the first electrode210, and the second electrode220. The first insulating layer510may be disposed on a side opposite to the area between the inner banks410and420with respect to the inner banks410and420as well as in the area between the electrodes210and220or between the inner banks410and420being spaced apart from each other. In addition, the first insulating layer510is disposed to partially cover the first electrode210and the second electrode220. For example, the first insulating layer510may be disposed entirely on the first electrode210, the second electrode220, and the first planarization layer109, and may be disposed to expose a portion of an upper surface of each of the first electrode210and the second electrode220. An opening (not shown) partially exposing the first electrode210and the second electrode220may be formed in the first insulating layer510, and the first insulating layer510may be disposed to cover only a first side and a second side of each of the first electrode210and the second electrode220. Some of the first electrode210and the second electrode220, which are disposed on the inner banks410and420, may be partially exposed by the opening.

The first insulating layer510may protect the first electrode210and the second electrode220and insulate the first electrode210from the second electrode220from each other. In addition, the first insulating layer510may prevent the light-emitting element300, disposed on the first insulating layer510, from being damaged by directly contacting other members. However, the shape and structure of the first insulating layer510are not limited thereto.

In an embodiment, a stepped portion may be formed on a portion of an upper surface of the first insulating layer510between the first electrode210and the second electrode220. In some embodiments, the first insulating layer510may include an inorganic insulating material, and a portion of the upper surface of the first insulating layer510disposed to partially cover the first electrode210and the second electrode220may be stepped by the stepped portion that is formed by the electrodes210and220disposed below the first insulating layer510. Accordingly, an empty space may be formed between the light-emitting element300, which is disposed on the first insulating layer510between the first electrode210and the second electrode220, and the upper surface of the first insulating layer510. The empty space may be filled with a material forming the second insulating layer520, which will be described below.

However, the disclosure is not limited thereto. The first insulating layer510may be formed such that a portion thereof disposed between the first electrode210and the second electrode220has a flat upper surface. The upper surface extends in a direction toward the first electrode210and the second electrode220, and the first insulating layer510may also be disposed in areas in which the electrodes210and220overlap the inclined side surfaces of the first inner bank410and the second inner bank420, respectively. The contact electrodes260, which will be described below, may contact the exposed areas of the first electrode210and the second electrode220and may smoothly contact end portions of the light-emitting element300on the flat upper surface of the first insulating layer510.

The outer bank450may be disposed on the first insulating layer510. As shown inFIGS.2and3, the outer bank450may be disposed at a boundary between the sub-pixels PXn. The outer bank450may be disposed to extend at least in the second direction DR2to surround the area in which the light-emitting element300is disposed between the inner banks410and420and between the electrodes210and220, and some of the inner banks410and420and the electrodes210and220. In addition, the outer bank450may further include a portion extending in the first direction DR1, and may form a grid pattern on the entire surface of the display area DPA.

According to an embodiment, a height of the outer bank450may be greater than a height of each of the inner banks410and420. Unlike the inner banks410and420, the outer bank450may divide adjacent sub-pixels PXn, and as will be described below, prevent the ink from overflowing into the adjacent sub-pixel PXn in the inkjet printing process for disposing the light-emitting element300during the manufacturing process of the display device10. For example, the outer bank450may separate inks, in which different light-emitting elements300are dispersed, from each other in different sub-pixels PXn so as to prevent the inks from being mixed with each other. Similar to the inner banks410and420, the outer bank450may include polyimide (PI), but the disclosure is not limited thereto.

The light-emitting element300may be disposed in an area formed between the first electrode210and the second electrode220, or between the first inner bank410and the second inner bank420. A first end portion of the light-emitting element300may be electrically connected to the first electrode210, and a second end portion thereof may be electrically connected to the second electrode220. The light-emitting element300may be electrically connected to the first electrode210and the second electrode220, respectively, through the contact electrodes260.

The light-emitting elements300may be disposed to be spaced apart from each other and aligned to be substantially parallel to each other. A distance between the light-emitting elements300is not particularly limited. In some embodiments, the light-emitting elements300may be disposed adjacent to each other to form a group and other light-emitting elements300may be grouped in a state of being spaced apart from each other at an interval, and may be oriented and aligned in a direction with a nonuniform density. In addition, in an embodiment, the light-emitting element300may have a shape extending in a direction, and a direction in which each of the electrodes210and220extends may be substantially perpendicular to a direction in which the light-emitting element300extends. However, the disclosure is not limited thereto, and the light-emitting element300may be obliquely disposed without being perpendicular to the direction in which each of the electrodes210and220extends.

The light-emitting elements300according to an embodiment may include active layers330having different materials to emit light in different wavelength ranges to the outside. The display device10according to an embodiment may include the light-emitting elements300emitting light in different wavelength ranges. The light-emitting element300of the first sub-pixel PX1may include an active layer330that emits light of a first color having a first wavelength as a central wavelength band, the light-emitting element300of the second sub-pixel PX2may include an active layer330that emits light of a second color having a second wavelength as a central wavelength band, and the light-emitting element300of the third sub-pixel PX3may include an active layer330that emits light of a third color having a third wavelength as a central wavelength band.

Thus, the light of the first color may be emitted from the first sub-pixel PX1, the light of the second color may be emitted from the second sub-pixel PX2, and the light of the third color may be emitted from the third sub-pixel PX3. In some embodiments, the light of the first color may be blue light having a central wavelength band ranging from about 450 nm to about 495 nm, the light of the second color may be green light having a central wavelength band ranging from about 495 nm to about 570 nm, and the light of the third color may be red light having a central wavelength band ranging from about 620 nm to about 752 nm. However, the disclosure is not limited thereto. In some embodiments, the first sub-pixel PX1, the second sub-pixel PX2, and the third sub-pixel PX3may include a same type of light-emitting elements300to emit light of a substantially same color.

The light-emitting element300may be disposed on an area between the inner banks410and420or on the first insulating layer510between the electrodes210and220. For example, the light-emitting element300may be disposed on the first insulating layer510disposed between the inner banks410and420. The light-emitting element300may be disposed such that an area thereof overlaps each of the electrodes210and220in the thickness direction. A first end portion of the light-emitting element300may overlap the first electrode210in the thickness direction and may be placed on the first electrode210, and a second end portion thereof may overlap the second electrode220in the thickness direction and may be placed on the second electrode220. However, the disclosure is not limited thereto, and although not shown in the drawing, at least some of the light-emitting elements300disposed in each sub-pixel PXn may be disposed in an area other than an area formed between the inner banks410and420, for example, between the inner banks410and420and the outer bank450.

The light-emitting element300may include layers disposed therein in a direction parallel to an upper surface of the first substrate101or the first planarization layer109. The light-emitting element300of the display device10according to an embodiment may have a shape extending in a direction and have a structure in which semiconductor layers are sequentially disposed in a direction. The light-emitting element300may be disposed such that a direction, in which the light-emitting element300extends, is parallel to the first planarization layer109, and the semiconductor layers included in the light-emitting element300may be sequentially disposed in the direction parallel to the upper surface of the first planarization layer109. However, the disclosure is not limited thereto. In some embodiments, in case that the light-emitting element300has a different structure, the layers may be disposed in a direction perpendicular to the first planarization layer109.

As described above, during the manufacturing process of the display device10, the light-emitting elements300may be sprayed onto the first electrode210and the second electrode220by the inkjet printing process in a state of being dispersed in the ink. In case that an alignment signal is applied to the electrodes210and220, an electric field is formed by the alignment signal so that the light-emitting elements300may receive a dielectrophoretic force to be aligned between the electrodes210and220. Here, the light-emitting element300according to an embodiment may include semiconductor layers or an insulating layer380(seeFIG.4) surrounding a semiconductor core, and the insulating layer380may include an insulating film381(seeFIG.5) and an element dispersion agent385(seeFIG.5) including a magnetic metal and bonded to the insulating film381. A magnetic force may be applied to the magnetic metal included in the element dispersion agent385by a magnetic field applied thereto from the outside, and the magnetic force may be transmitted to the light-emitting element300. According to a direction of the magnetic force, the light-emitting elements300may maintain a dispersed state in the ink for a long period of time. Accordingly, the light-emitting elements300according to an embodiment may maintain a dispersed state without being precipitated in the ink during the process of manufacturing the display device10, and may have a uniform degree of dispersion in the ink sprayed onto the first electrode210and the second electrode220. A detailed description of the structure of the light-emitting element300will be provided below with reference to other drawings.

The second insulating layer520may be partially disposed on the light-emitting element300disposed between the first electrode210and the second electrode220. For example, the second insulating layer520may be disposed on the first insulating layer510between the first electrode210and the second electrode220, and the light-emitting element300may be disposed between the first insulating layer510and the second insulating layer520. In an embodiment, in the light-emitting element300, the insulating layer380(seeFIG.4) formed on an outer surface of the light-emitting element300may directly contact the first insulating layer510and the second insulating layer520. For example, the second insulating layer520may be disposed to partially surround the outer surface of the light-emitting element300and thus may protect the light-emitting element300and may fix the light-emitting element300during the manufacturing process of the display device10. Accordingly, the element dispersion agent385of the light-emitting element300may directly contact each of the first insulating layer510and the second insulating layer520.

A portion of the second insulating layer520disposed on the light-emitting element300may have a shape extending in the second direction DR2between the first electrode210and the second electrode220in a plan view. As an example, the second insulating layer520may form a stripe or island type pattern in each sub-pixel PXn.

The second insulating layer520may be disposed on the light-emitting element300and may expose a first end portion and a second end portion of the light-emitting element300. The exposed first or second end portion of the light-emitting element300may contact the contact electrode260, which will be described below. Such a shape of the second insulating layer520may be formed by a patterning process using a material forming the second insulating layer520by using a mask process. A mask for forming the second insulating layer520has a width less than a length of the light-emitting element300, and the material forming the second insulating layer520is patterned to expose opposite end portions of the light-emitting element300. However, the disclosure is not limited thereto.

Further, in an embodiment, a portion of the material of the second insulating layer520may be disposed between the first insulating layer510and a lower surface of the light-emitting element300. The second insulating layer520may be formed to fill a space between the first insulating layer510and the light-emitting element300, which is formed during the manufacturing process of the display device10. Accordingly, the second insulating layer520may be formed to partially surround the outer surface of the light-emitting element300. However, the disclosure is not limited thereto.

The contact electrodes260and the third insulating layer530may be disposed on the second insulating layer520.

As shown inFIG.2, the contact electrodes260may each have a shape extending in one direction. The contact electrodes260may contact the respective electrodes210and220and the light-emitting elements300, and the light-emitting elements300may receive electrical signals from the first electrode210and the second electrode220through the contact electrodes260.

The contact electrodes260may include a first contact electrode261and a second contact electrode262. The first contact electrode261and the second contact electrode262may be disposed on the first electrode210and the second electrode220, respectively. The first contact electrode261may be disposed on the first electrode210, the second contact electrode262may be disposed on the second electrode220, and the first contact electrode261and the second contact electrode262may each extend in the second direction DR2. The first contact electrode261and the second contact electrode262may be spaced apart from each other and face each other in the first direction DR1and may form a stripe pattern in the light-emitting area EMA of each sub-pixel PXn.

In some embodiments, a width of each of the first contact electrode261and the second contact electrode262, which is measured in a direction, may be greater than or equal to a width of each of the first electrode210and the second electrode220, which is measured in the direction. The first contact electrode261and the second contact electrode262may be disposed to contact a first end portion and a second end portion of the light-emitting element300, respectively, and to cover side surfaces of the first electrode210and the second electrode220, respectively. As described above, the upper surface of each of the first electrode210and the second electrode220may be partially exposed, and the first contact electrode261and the second contact electrode262may contact the exposed upper surfaces of the first electrode210and the second electrode220, respectively. For example, the first contact electrode261may contact a portion of the first electrode210, which is located on the first inner bank410, and the second contact electrode262may contact a portion of the second electrode220, which is located on the second inner bank420. However, the disclosure is not limited thereto, and in some embodiments, the widths of the first contact electrode261and the second contact electrode262may be formed to be less than those of the first electrode210and the second electrode220, respectively, and the first contact electrode261and the second contact electrode262may be disposed to cover the exposed portions of the upper surfaces of the first electrode210and the second electrode220, respectively. In addition, as shown inFIG.3, at least a partial area of each of the first contact electrode261and the second contact electrode262is disposed on the first insulating layer510.

According to an embodiment, the light-emitting element300has the semiconductor layer exposed on end surfaces thereof in an extending direction, and the first contact electrode261and the second contact electrode262may contact the light-emitting element300on the end surfaces where the semiconductor layer is exposed. However, the disclosure is not limited thereto. In some embodiments, end side surfaces of the light-emitting element300may be partially exposed. During the manufacturing process of the display device10, the insulating layer380(seeFIG.4) surrounding an outer surface of the semiconductor layer of the light-emitting element300may be partially removed in a process of forming the second insulating layer520covering the outer surface of the light-emitting element300, and the exposed side surface of the light-emitting element300may contact the first contact electrode261and the second contact electrode262. A first end portion of the light-emitting element300may be electrically connected to the first electrode210through the first contact electrode261, and a second end portion thereof may be electrically connected to the second electrode220through the second contact electrode262.

FIG.2illustrates that a first contact electrode261and a second contact electrode262are disposed in a sub-pixel PXn, but the disclosure is not limited thereto. The numbers of the first contact electrodes261and second contact electrodes262may vary depending on the numbers of the first electrodes210and second electrodes220disposed in each sub-pixel PXn.

Further, as shown inFIG.3, the first contact electrode261is disposed on the first electrode210and the second insulating layer520. The first contact electrode261may contact a first end portion of the light-emitting element300and the exposed upper surface of the first electrode210. The first end portion of the light-emitting element300may be electrically connected to the first electrode210through the first contact electrode261.

The third insulating layer530is disposed on the first contact electrode261. The third insulating layer530may electrically insulate the first contact electrode261and the second contact electrode262from each other. Specifically, the third insulating layer530may be disposed to cover the first contact electrode261and may not be disposed on the second end portion of the light-emitting element300so that the light-emitting element300may contact the second contact electrode262. The third insulating layer530may partially contact the first contact electrode261and the second insulating layer520at an upper surface of the second insulating layer520. A side surface of the third insulating layer530in a direction in which the second electrode220is disposed may be aligned with a side surface of the second insulating layer520. In addition, the third insulating layer530may be disposed in a non-light-emitting area NEA, for example, on the first insulating layer510disposed on the first planarization layer109. However, the disclosure is not limited thereto.

The second contact electrode262is disposed on the second electrode220, the second insulating layer520, and the third insulating layer530. The second contact electrode262may contact the second end portion of the light-emitting element300and the exposed upper surface of the second electrode220. The second end portion of the light-emitting element300may be electrically connected to the second electrode220through the second contact electrode262.

For example, the first contact electrode261is disposed between the first electrode210and the third insulating layer530, and the second contact electrode262may be disposed on the third insulating layer530. The second contact electrode262may partially contact the second insulating layer520, the third insulating layer530, the second electrode220, and the light-emitting element300. A first end portion of the second contact electrode262in a direction in which the first electrode210is disposed may be disposed on the third insulating layer530. The first contact electrode261and the second contact electrode262may not contact each other by the second insulating layer520and the third insulating layer530. However, the disclosure is not limited thereto, and in some embodiments, the third insulating layer530may be omitted.

The contact electrode260may include a conductive material. For example, the contact electrode260may include ITO, IZO, ITZO, aluminum (Al), or the like. As an example, the contact electrode260may include a transparent conductive material, and light emitted from the light-emitting element300may pass through the contact electrode260and travel toward the electrodes210and220. Each of the electrodes210and220may include a material having a high reflectance, and the electrodes210and220disposed on the inclined side surfaces of the inner banks410and420may reflect incident light in an upward direction with respect to the first substrate101. However, the disclosure is not limited thereto.

The fourth insulating layer550may be disposed entirely on the first substrate101. The fourth insulating layer550may serve to protect members, disposed on the first substrate101, from an external environment.

Each of the first insulating layer510, the second insulating layer520, the third insulating layer530, and the fourth insulating layer550, which are described above, may include an inorganic insulating material or an organic insulating material. In an embodiment, the first insulating layer510, the second insulating layer520, the third insulating layer530, and the fourth insulating layer550may each include an inorganic insulating material such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum oxide (Al2O3), aluminum nitride (AlN), or the like. As another example, the first insulating layer510, the second insulating layer520, the third insulating layer530, and the fourth insulating layer550may each include an organic insulating material such as an acrylic resin, an epoxy resin, a phenol resin, a polyamide resin, a PI resin, an unsaturated polyester resin, a polyphenylene resin, a polyphenylene sulfide resin, benzocyclobutene, a cardo resin, a siloxane resin, a silsesquioxane resin, polymethyl methacrylate, polycarbonate, or a polymethyl methacrylate-polycarbonate synthetic resin. However, the disclosure is not limited thereto.

The light-emitting element300may be a light-emitting diode, and specifically, may be an inorganic light-emitting diode having a size of a micrometer unit or a nanometer unit and made of (or include) an inorganic material. The inorganic light-emitting diode may be aligned between two electrodes in which polarity is formed by forming an electric field in a specific direction between the two electrodes facing each other. The light-emitting element300may be aligned between two electrodes by the electric field formed on the two electrodes.

The light-emitting element300according to an embodiment may have a shape extending in one direction. The light-emitting element300may have a shape of a rod, a wire, a tube, or the like. In an embodiment, the light-emitting element300may have a cylindrical shape or a rod shape. However, the shape of the light-emitting element300is not limited thereto, and the light-emitting element300may have a shape of a cube, a rectangular parallelepiped, a polygonal pillar such as a hexagonal pillar or the like or have a shape which extends in a direction and has a partially inclined outer surface. Thus, the light-emitting element300may have various shapes. Semiconductors included in the light-emitting element300, which will be described below, may have a structure in which the semiconductors are sequentially disposed or stacked in the direction.

The light-emitting element300may include a semiconductor core and an insulating layer surrounding the semiconductor core. The semiconductor core of the light-emitting element300may include a semiconductor layer doped with an arbitrary conductive-type (for example, p-type or n-type) impurity. The semiconductor layer may receive an electrical signal applied from an external power source and emit light in a specific wavelength range.

FIG.4is a schematic view of the light-emitting element according to an embodiment.

Referring toFIG.4, the light-emitting element300may include a first semiconductor layer310, a second semiconductor layer320, an active layer330, an electrode layer370, and an insulating layer380. The light-emitting element300may include the semiconductor core including the first semiconductor layer310, the second semiconductor layer320, and the active layer330, and the insulating layer380surrounding an outer surface of the semiconductor core.

The first semiconductor layer310may be a semiconductor doped with a first polarity dopant and may be an n-type semiconductor. As an example, in case that the light-emitting element300emits light in a blue wavelength range, the first semiconductor layer310may include a semiconductor material having a chemical formula of AlxGayInl-x-yN (0≤x≤1, 0≤y≤1, and 0≤x+y≤1). For example, the semiconductor material may be one or more among AlGaInN, GaN, AlGaN, InGaN, AlN, and InN that are doped with an n-type impurity. The first semiconductor layer310may be doped with an n-type dopant. As an example, the n-type dopant may be Si, Ge, Sn, or the like. In an embodiment, the first semiconductor layer310may be n-GaN doped with n-type Si. A length of the first semiconductor layer310may range from about 1.5 μm to about 5 μm, but the disclosure is not limited thereto.

The second semiconductor layer320is disposed on the active layer330to be described below. For example, the second semiconductor layer320may be a semiconductor doped with a second polarity dopant different from the first polarity dopant and may be a p-type semiconductor. As an example, in case that the light-emitting element300emits light in a blue or green wavelength range, the second semiconductor layer320may include a semiconductor material having a chemical formula of AlxGayInl-x-yN (0≤x≤1, 0≤y≤1, and 0≤x+y≤1). For example, the semiconductor material may be one or more among AlGaInN, GaN, AlGaN, InGaN, AlN, and InN that are doped with a p-type impurity. The second semiconductor layer320may be doped with a p-type dopant. As an example, the p-type dopant may be Mg, Zn, Ca, Se, Ba, or the like. In an embodiment, the second semiconductor layer320may be p-GaN doped with p-type Mg. A length of the second semiconductor layer320may range from about 0.05 μm to about 0.10 μm, but the disclosure is not limited thereto.

FIG.4illustrates that each of the first semiconductor layer310and the second semiconductor layer320is formed as a layer, but the disclosure is not limited thereto. According to some embodiments, each of the first semiconductor layer310and the second semiconductor layer320may further include a larger number of layers, e.g., a clad layer or a tensile strain barrier reducing (TSBR) layer according to a material of the active layer330. A description thereof will be provided below with reference to other drawings.

The active layer330is disposed between the first semiconductor layer310and the second semiconductor layer320. The active layer330may include a material having a single or multiple quantum well structure. In case that the active layer330includes a material having a multiple quantum well structure, the active layer330may have a structure in which quantum layers and well layers are alternately stacked. The active layer330may emit light by a combination of electron-hole pairs in response to electrical signals applied thereto through the first semiconductor layer310and the second semiconductor layer320. As an example, in case that the active layer330emits light in a blue wavelength range, the active layer330may include a material such as AlGaN, AlGaInN, or the like. In particular, in case that the active layer330has a multiple quantum well structure in which quantum layers and well layers are alternately stacked, the quantum layer may include a material such as AlGaN or AlGaInN, and the well layer may include a material such as GaN or AlInN. In an embodiment, the active layer330includes AlGaInN as a quantum layer and AlInN as a well layer. As described above, the active layer330may emit blue light having a central wavelength band ranging from about 450 nm to about 495 nm.

However, the disclosure is not limited thereto, and the active layer330may have a structure in which a semiconductor material having large bandgap energy and a semiconductor material having small bandgap energy are alternately stacked or include other group III to group V semiconductor materials according to the wavelength range of emitted light. The light emitted by the active layer330is not limited to light in a blue wavelength range, and the active layer330may also emit light in a red or green wavelength range in some embodiments. A length of the active layer330may range from about 0.05 μm to about 0.10 μm, but the disclosure is not limited thereto.

The light emitted from the active layer330may be emitted to not only an outer surface of the light-emitting element300in a length direction but also the side surfaces of the light-emitting element300. Directivity of the light emitted from the active layer330is not limited to one direction.

The electrode layer370may be an ohmic contact electrode. However, the disclosure is not limited thereto, and the electrode layer370may also be a Schottky contact electrode. The light-emitting element300may include at least one electrode layer370. AlthoughFIG.4illustrates that the light-emitting element300includes a single electrode layer370, the disclosure is not limited thereto. In some embodiments, the light-emitting element300may include a larger number of electrode layers370, or the electrode layer370may be omitted. The description of the light-emitting element300, which will be provided below, may be identically applied even in case that the number of the electrode layers370is varied or another structure is further included.

In case that the light-emitting element300is electrically connected to the electrodes210and220or the contact electrode260, the electrode layer370may reduce resistance between the light-emitting element300and the electrode or contact electrode. The electrode layer370may include a conductive metal. For example, the electrode layer370may include at least one among aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin-zinc oxide (ITZO). Further, the electrode layer370may include a semiconductor material doped with an n-type or p-type impurity. The electrode layer370may include a same material or different materials, but the disclosure is not limited thereto.

The insulating layer380is disposed to surround outer surfaces of the semiconductor layers and the electrode layers, which are described above. In an embodiment, the insulating layer380may be disposed to surround at least an outer surface of the active layer330and may extend in a direction in which the light-emitting element300extends. The insulating layer380may serve to protect the members. As an example, the insulating layer380may be formed to surround side surfaces of the members and expose end portions of the light-emitting element300in the length direction.

FIG.4illustrates that the insulating layer380is formed to extend in the length direction of the light-emitting element300to cover from the first semiconductor layer310to a side surface of the electrode layer370, but the disclosure is not limited thereto. Since the insulating layer380covers only the outer surfaces of some semiconductor layers including the active layer330or covers only a portion of the outer surface of the electrode layer370, the outer surface of the electrode layer370may be partially exposed. In addition, an upper surface of the insulating layer380may be formed to be rounded in an area thereof adjacent to at least one first portion of the light-emitting element300, in a cross-sectional view.

A thickness of the insulating layer380may range from about 10 nm to about 1.0 μm, but the disclosure is not limited thereto. The thickness of the insulating layer380may be about 40 nm.

The light-emitting element300may have a length h ranging from about 1 μm to about 10 μm or from about 2 μm to about 6 μm, or from about 3 am to about 5 μm. In addition, a diameter of the light-emitting element300may range from about 300 nm to about 700 nm, and an aspect ratio of the light-emitting element300may range from about 1.2 to 100. However, the disclosure is not limited thereto, and the light-emitting elements300included in the display device10may have different diameters according to a composition difference of the active layer330. The diameter of the light-emitting element300may have a range of about 500 nm.

As described above, in the light-emitting element300according to an embodiment, the insulating layer380may include the insulating film381and the element dispersion agent385. The element dispersion agent385may be bonded to an outer surface of the insulating film381and may include a magnetic metal. The light-emitting elements300may each include the element dispersion agent385including a magnetic metal to receive a magnetic force directed toward a specific direction and maintain a dispersed state in the ink for a long period of time.

Specifically, the insulating film381may be formed to surround outer surfaces of the semiconductor layers of the light-emitting element300. For example, the insulating film381may be formed to surround at least the outer surface of the active layer330, and may extend in a direction in which the light-emitting element300extends, for example, a direction in which the first semiconductor layer310, the active layer330, and the second semiconductor layer320are stacked. As described above, the insulating film381may be formed to surround the active layer330and the outer surfaces of the first semiconductor layer310, the second semiconductor layer320, and the electrode layer370.

The insulating film381may include at least one selected from among materials having insulating properties, for example, silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum nitride (AlN), aluminum oxide (Al2O3), or the like. Accordingly, it is possible to prevent an electrical short circuit which may occur in case that the active layer330directly contacts the electrode through which an electrical signal is transmitted to the light-emitting element300. Further, since the insulating film381protects the outer surface of the light-emitting element300including the active layer330, it is possible to prevent degradation in light-emitting efficiency.

The element dispersion agent385may include a magnetic metal. According to an embodiment, the element dispersion agent385may include a ligand385pforming a coordination bond with the magnetic metal, and a first functional group385abonded to the ligand385pto form a chemical bond with the insulating film381. In addition, the element dispersion agent385may include a second functional group385b(“Y” inFIG.5) bonded to the ligand385pand different from the first functional group385a.

FIG.5is a schematic enlarged view of portion A ofFIG.4.FIG.5schematically illustrates the insulating film381and the element dispersion agent385by enlarging an outer surface of the insulating layer380ofFIG.4.

Referring toFIG.5in conjunction withFIG.4, the ligand385p(“P” inFIG.5) of the element dispersion agent385may form a coordination bond with the magnetic metal (not shown). The magnetic metal may form a coordination bond with the ligand385p. As will be described below, in case that a magnetic field is applied to the light-emitting element300, a magnetic force may be applied to the magnetic metal in a direction due to the magnetic field. The light-emitting elements300may receive the magnetic force that the magnetic metal receives, and may maintain a dispersed state for a long period of time because a precipitation rate of the light-emitting element in the ink is reduced. In some embodiments, during the manufacturing process of the display device10, the light-emitting elements300may be uniformly dispersed in a state in which the magnetic field is applied, and sprayed by an inkjet printing process.

The types of the ligand385pand the magnetic metal are not particularly limited. For example, the ligand385pis not particularly limited as long as it has a structure capable of fixing a magnetic metal by forming a coordination bond with the magnetic metal as a central metal. In an embodiment, the ligand385pmay be a porphyrin structure, a multi-dentate structure, or the like, and the magnetic metal may be Fe, Mn, Co, Ni, Cr, or the like, but the disclosure is not limited thereto.

The first functional group385a(“X” inFIG.5) of the element dispersion agent385may be bonded to the ligand385pto form a chemical bond with an outer surface of the insulating film381. For example, the first functional group385amay form a covalent bond with the material forming the insulating film381, and the ligand385pforming a coordination bond with the magnetic metal may be bonded to the insulating film381through the first functional group385a.

The first functional group385amay include a bonding portion that forms a chemical bond with the insulating film381, and a connection portion that is connected to the bonding portion to be bonded to the ligand385p. In an embodiment, the insulating film381may include a material such as aluminum oxide (Al2O3) or silicon oxide (SiOx) as described above, and the bonding portion of the first functional group385amay be one of functional groups such as a silane group, a boronate group, a carboxylic acid group, an amine group, a thiol group, and a phosphoric acid group. However, the disclosure is not limited thereto.

Further, the first functional group385amay include an alkenyl group, an alkynyl group, or the like having about 1 to about 6 carbon atoms as the connection portion. For example, the first functional group385amay include a carbon chain having a single bond. The carbon chain having a single bond may be capable of single bond rotation, and the ligand385pand the magnetic metal bonded to the insulating film381through the first functional group385amay be oriented in random directions. However, in case that a magnetic field is formed in the ink in which the light-emitting elements300are dispersed, a magnetic force due to the magnetic field may be applied to the magnetic metal in a direction, the connection portion of the first functional group385ais rotated, and the element dispersion agent385may be oriented in a same direction.

The element dispersion agent385may further include at least one second functional group385bbonded to the ligand385p. The second functional group385bmay be a functional group different from the first functional group385a. As described above, the light-emitting elements300may be prepared in a state of being dispersed in the ink, and the outer surface of each of the light-emitting elements300may be surface-treated so that the light-emitting elements300do not aggregate with other light-emitting elements300. According to an embodiment, in the insulating layer380of the light-emitting element300, the element dispersion agent385may further include the second functional group385bincluding a hydrophobic functional group, and the light-emitting elements300may be dispersed in the ink without being aggregated with each other. In some embodiments, the second functional group385bmay be an alkyl group having about 1 to about 6 carbon atoms, a fluoroalkyl group having about 1 to about 6 carbon atoms, or a cycloalkyl group having about 3 to about 6 carbon atoms, and or the like, but the disclosure is not limited thereto.

In an embodiment, the element dispersion agent385of the light-emitting element300may have a structure represented by any of Chemical Formulas A to D below.

In Chemical Formulas A to D, M is at least one of Fe2+, Mn2+, Co2+, Ni2+, and Cr2+, R1is at least one of a silane group, a boronate group, a carboxylic acid group, an amine group, a thiol group, and a phosphoric acid group, R2to R4are each independently one of hydrogen, an alkyl group having about 1 to about 6 carbon atoms, a fluoroalkyl group having about 1 to about 6 carbon atoms, and a cycloalkyl group having about 3 to about 6 carbon atoms, n is an integer of 1 to 6, and a dash line indicates a coordination bond.

The element dispersion agent385may have a structure represented by one of Chemical Formulas A to D described above. In Chemical Formulas A to D, M may be the magnetic metal, R1may be the bonding portion of the first functional group385a, and R2to R4may be the second functional group385b.

As described above, the element dispersion agent385may include the ligand385pthat forms a coordination bond with the magnetic metal as a central metal. As an example, the ligand385pof the element dispersion agent385may be a porphyrin structure or a multi-dentate structure. Chemical Formula A is a case in which the ligand385pis a porphyrin structure, and at least some of the four nitrogen atoms (N) of the porphyrin structure may form a coordination bond with the magnetic metal (M). In addition, Chemical Formulas B to D are cases in which the ligand385pis a multi-dentate structure, and at least some of oxygen atoms (O) or nitrogen atoms (N) of the dentate structure may form a coordination bond with the magnetic metal. The magnetic metal may form a coordination bond with the ligand385pin the form of an ion with a charge.

Further, the first functional group385amay include R1corresponding to the bonding portion and —CnH2ncorresponding to the connection portion. R1may form a chemical bond, e.g., a covalent bond, with the insulating film381of the insulating layer380, and a carbon chain (—CnH2n) corresponding to the connection portion may be bonded to the porphyrin structure or the dentate structure. R2to R4corresponding to the second functional group385bmay include a hydrophobic functional group as described above. However, in case that R2to R4are each independently hydrogen, the element dispersion agent385may be a structure that does not include the second functional group385b.

The magnetic metal (M) may be fixed to the ligand385pby forming a coordination bond therewith. In case that the light-emitting element300including the element dispersion agent385is placed in a magnetic field directed in a direction, the magnetic metal (M) may receive a magnetic force according to the direction of the magnetic field. For example, the light-emitting element300may receive a magnetic force directed in a direction opposite to a gravity direction according to the direction of the magnetic field, and a precipitation rate of the light-emitting element300in the ink in which the magnetic field is formed may be reduced.

FIG.6is a schematic view illustrating a case in which a magnetic field is applied to the light-emitting elements according to an embodiment.FIG.7is a schematic enlarged view of portion B ofFIG.6

Describing in detail with reference toFIGS.6and7, the light-emitting elements300according to an embodiment each include the insulating layer380including the element dispersion agent385, and thus may be prepared in a state of being dispersed in an ink S in the manufacturing process of the display device10.

The ink S may be an organic solvent capable of storing the light-emitting elements300in a dispersed state without reacting with the light-emitting elements300. In addition, the ink S may be a material that is vaporized or volatilized by heat. As will be described below, after aligning the light-emitting elements300between the electrodes210and220during the manufacturing process of the display device10, the ink S may be volatilized and removed by a heat treatment process. In other words, the ink S may have a viscosity sufficient to smoothly disperse the light-emitting elements300, and may have a boiling point or viscosity that may be readily volatilized by heat. For example, the ink S may be propylene glycol monomethylether (PGME), propylene glycol monomethylether acetate (PGMEA), propylene glycol (PG), acetone, alcohol, toluene, or the like. However, the disclosure is not limited thereto.

As described above, the light-emitting element300includes the semiconductor layer having a high specific gravity, or a semiconductor core. As shown inFIG.7, the light-emitting elements300dispersed in the ink S may receive gravity F1and may be precipitated into a lower surface of a container in which the ink S is prepared. In case that the light-emitting element300is precipitated in the ink S, the number of the light-emitting elements300included in the ink S may be non-uniform in the process of spraying the ink S during the manufacturing process of the display device10.

However, the light-emitting element300according to an embodiment may include the element dispersion agent385including a magnetic metal (M), and may receive a magnetic force directed in a direction when placed in a magnetic field directed in the direction. As shown inFIG.7, in case that a magnetic field B0is formed in the ink S in a direction opposite to the gravity direction, a magnetic force may be applied to the magnetic metal included in the element dispersion agent385of the light-emitting element300in a direction parallel to the direction of the magnetic field B0. As in Chemical Formulas A to D, the magnetic metal may form a coordination bond with the ligand385pin the form of an ion with a charge. A magnetic force that is an attractive or repulsive force depending on the direction of the magnetic field B0may be applied to the magnetic metal with a charge.

The magnetic force F2(seeFIG.6) applied to the magnetic metal of the element dispersion agent385may be transmitted to the light-emitting element300, and in some embodiments, a direction in which the magnetic field B0is formed may be a direction opposite to the gravity direction. For example, the light-emitting element300may receive a magnetic force F2directed in a direction opposite to the gravity direction according to the direction of the magnetic field B0. Accordingly, the light-emitting elements300according to an embodiment may maintain a dispersed state for a long period of time because a precipitation rate of the light-emitting element300is reduced in the ink S, and the light-emitting elements300may be sprayed in a state of being uniformly dispersed by an inkjet printing process during the manufacturing process of the display device10.

Although not shown in the drawing, a method of applying the magnetic field B0to the light-emitting element300is not particularly limited. For example, the magnetic field B0may be formed by a coil surrounding a container in which the ink S in which the light-emitting elements300are dispersed is prepared, and in some embodiments, a magnetic field B0may be applied from a device prepared outside the container.

Hereinafter, a method of manufacturing the display device10according to an embodiment will be described with reference to other drawings.

FIG.8is a flowchart illustrating a method of manufacturing the display device according to an embodiment.

Referring toFIG.8, the method of manufacturing the display device10according to an embodiment may include preparing an ink S in which light-emitting elements300are dispersed, and applying a magnetic field to the light-emitting elements300(S1), preparing a target substrate SUB on which a first electrode210and a second electrode220disposed to be spaced apart from each other are formed, and spraying the ink S on the target substrate SUB (S2), and generating an electric field on the target substrate SUB to place the light-emitting element300between the first electrode210and the second electrode220(S3).

The magnetic field may be applied to the light-emitting elements300prepared in a state of being dispersed in the ink S. As described above, in case that the magnetic field is applied, a magnetic force that the magnetic metal included in the element dispersion agent385receives may be transmitted to the light-emitting element300so that a precipitation rate of the light-emitting element300may be reduced. The light-emitting elements300may maintain a uniformly dispersed state before being sprayed onto the target substrate SUB, on which is disposed between the first electrode210and the second electrode220, by an inkjet printing process. Hereinafter, the manufacturing process of the display device10will be described in detail with further reference to other drawings.

First, as described above with reference toFIGS.6and7, an ink S in which light-emitting elements300each including a semiconductor core and an insulating layer380are dispersed is prepared, and a magnetic field is applied to the light-emitting elements300(S1). A magnetic force may be applied to a magnetic metal in an element dispersion agent385of the light-emitting element300by the magnetic field, and the magnetic force may be transmitted to the light-emitting element300. According to an embodiment, during the manufacturing process of the display device10, the magnetic force may be applied to the light-emitting element300in a direction opposite to a gravity direction in the applying of the magnetic field (S1).

As will be described below, in the process of spraying the ink S in which the light-emitting elements300are dispersed, a magnetic field is applied to the light-emitting elements300in a direction so that the light-emitting elements300may maintain a uniformly dispersed state in the ink S. The magnetic field may be applied such that the magnetic force transmitted to the light-emitting element300is directed toward the direction opposite to the gravity direction. As shown inFIG.6, a magnetic force F2may be transmitted to the light-emitting element300in the direction opposite to the gravity F1, and a precipitation rate of the light-emitting element300may be reduced in the ink S.

FIG.9is a schematic cross-sectional view illustrating an operation of the manufacturing process of the display device according to an embodiment.

Referring toFIG.9, a target substrate SUB on which a first electrode210and a second electrode220are disposed is prepared. AlthoughFIG.9illustrates only the target substrate SUB, the first electrode210, and the second electrode220for convenience of description, conductive layers and insulating layers disposed below the first electrode210and the second electrode220may be further disposed in the display device10as described above. For example, the target substrate SUB ofFIG.9may be understood as including the first substrate101ofFIG.3and including conductive layers and insulating layer disposed on the first substrate101. Since descriptions thereof are the same as described above, detailed descriptions thereof will be omitted.

FIGS.10and11are schematic cross-sectional views illustrating an operation of the manufacturing process of the display device according to an embodiment.

Subsequently, referring toFIG.10, the ink S in which the light-emitting elements300are dispersed is sprayed onto the first substrate101(S2). In an embodiment, the ink S may be sprayed onto the first substrate101by a printing process using an inkjet printing device (not shown). The ink S in which the light-emitting elements300are dispersed may be prepared in the inkjet printing device, and, as described above, the magnetic field directed in a direction may be formed in the ink S.

According to an embodiment, the ink S may be sprayed onto the first substrate101in a state in which a magnetic field B0is applied. As described above, the display device10includes pixels PX and sub-pixels PXn, and the ink S in which the light-emitting elements300are dispersed may be sprayed in each sub-pixel PXn in the inkjet printing process. The inkjet printing process may be performed in a state in which a magnetic field is applied to the light-emitting elements300, so that the light-emitting elements300may maintain a uniformly dispersed state during the process of spraying the ink S. Accordingly, a uniform number of light-emitting elements300may be dispersed in the ink S sprayed in each pixel PX or sub-pixel PXn.

Referring toFIG.12, in case that an ink S′ is sprayed in a state in which the magnetic field is not applied to the light-emitting elements300, some of the light-emitting elements300may be precipitated on a lower surface of a container in which the ink S′ is prepared. In this case, in the inkjet printing process, a smaller number of light-emitting elements300may be included in the ink S′ sprayed onto some sub-pixels PXn than in the ink S′ sprayed onto the other sub-pixels PXn.

The method of manufacturing the display device10according to an embodiment may perform spraying the ink S in a state in which a magnetic field is applied to the light-emitting elements300, and the ink S sprayed in each sub-pixel PXn may include a uniform number of light-emitting elements300. Accordingly, in the display device10, a uniform number of light-emitting elements300may be disposed in each of the pixels PX or sub-pixels PXn.

FIG.12is a schematic cross-sectional view illustrating an operation of the manufacturing process of the display device according to an embodiment.FIG.13is a schematic view illustrating a case in which the light-emitting elements in the operation ofFIG.12are aligned.

Referring toFIGS.12and13, an electric field is generated on the target substrate SUB to dispose (or place) the light-emitting elements300between the first electrode210and the second electrode220(S3). In case that an alignment signal is applied to the first electrode210and the second electrode220, an electric field E may be generated on the target substrate SUB. In an embodiment, the alignment signal may be an alternating current (AC) voltage, and the AC voltage may have a voltage of about ±10 to about ±50 V and a frequency of about 10 kHz to about 1 MHz.

In case that the AC voltage is applied to the first electrode210and the second electrode220, the electric field E is generated therebetween, and the electric field E may be applied to the light-emitting elements300dispersed in the ink S. The light-emitting elements300to which the electric field E is applied may receive a dielectrophoretic force FE (seeFIG.13) in the ink S, and the light-emitting elements300receiving the dielectrophoretic force FE may be placed between the first electrode210and the second electrode220while the orientation direction and position of each of the light-emitting elements300are changed.

According to an embodiment, in the disposing of the light-emitting element300, the electric field E may cause a first end portion of each of the light-emitting elements300to be disposed on the first electrode210, and a second end portion thereof to be disposed on the second electrode220. As shown inFIG.13, end portions of each of the light-emitting elements300may move from initial sprayed positions (a dotted line portion ofFIG.13) toward the electrodes210and220, respectively, and each of the light-emitting elements300may be oriented such that an extending direction thereof is directed in a direction. Although end portions of each of the light-emitting elements300may be disposed on the electrodes210and220, respectively, the disclosure is not limited thereto, and in some embodiments, the light-emitting elements300may be disposed between the electrodes210and220.

FIG.14is a schematic cross-sectional view illustrating an operation of the manufacturing process of the display device according to an embodiment.

Referring toFIG.14, the ink S sprayed onto the target substrate SUB is removed. The removing of the ink S may be performed by a heat treatment device, and the heat treatment device may emit heat or infrared light onto the target substrate SUB. As the ink S sprayed onto the target substrate SUB is removed, the light-emitting elements300may be prevented from moving and may be placed between the electrodes210and220.

The display device10according to an embodiment may be manufactured by the above-described processes. The manufacturing process of the display device10includes applying a magnetic field to the light-emitting elements300each including the element dispersion agent385. In case that the magnetic field is applied to the light-emitting element300, a magnetic force may be applied to the magnetic metal of the element dispersion agent385, and the magnetic force may be transmitted to the light-emitting element300. The light-emitting elements300may maintain a dispersed state in the ink S in which the magnetic field is formed, and the ink S to be sprayed in the inkjet printing process may include a uniform number of light-emitting elements300. Accordingly, in the display device10, each sub-pixel PXn may include a uniform number of light-emitting elements300.

Hereinafter, various embodiments of the light-emitting element300and the display device10according to an embodiment will be described.

The structure of the light-emitting element300is not limited to that shown inFIG.4and may have another structure.

FIG.15is a schematic view of a light-emitting element according to another embodiment.

Referring toFIG.15a light-emitting element300′ according to an embodiment may have a shape extending in a direction and having a partially inclined side surface. For example, the light-emitting element300′ according to an embodiment may have a partially conical shape. The light-emitting element300′ ofFIG.15is identical to the light-emitting element300ofFIG.4except that shapes of the layers are partially different. Hereinafter, the same contents will be omitted, and differences will be described.

###The light-emitting element300′ may be formed such that layers are not stacked in a direction and each of the layers surrounds an outer surface of another layer. The light-emitting element300′ ofFIG.15may be formed such that semiconductor layers surround at least a portion of an outer surface of another layer. The light-emitting element300′ may include a semiconductor core of which at least a partial area partially extends in a direction and an insulating layer380′ formed to surround the semiconductor core. The semiconductor core may include a first semiconductor layer310′, an active layer330′, a second semiconductor layer320′, and an electrode layer370′.

According to an embodiment, the first semiconductor layer310′ may extend in a direction and end portions thereof may be formed to be inclined toward a center portion thereof. The first semiconductor layer310′ ofFIG.15may have a shape in which a rod-shaped or cylindrical main body portion and end portions having inclined side surfaces. An upper end portion of the main body portion may have a steeper slope than a lower end portion thereof.

The active layer330′ is disposed to surround an outer surface of the main body portion of the first semiconductor layer310′. The active layer330′ may have an annular shape extending in a direction. The active layer330′ may not be formed on upper and lower end portions of the first semiconductor layer310′. The active layer330′ may be formed only on a non-inclined side surface of the first semiconductor layer310′. However, the disclosure is not limited thereto. Accordingly, light emitted from the active layer330′ may be emitted to not only end portions of the light-emitting element300′ in a length direction but also side surfaces thereof based on the length direction. When compared with the light-emitting element300ofFIG.4, the light-emitting element300′ ofFIG.15may include the active layer330′ having a larger area, thereby emitting a larger amount of light.

The second semiconductor layer320′ is disposed to surround an outer surface of the active layer330′ and the upper end portion of the first semiconductor layer310′. The second semiconductor layer320′ may include an annular main body portion extending in a direction and an upper end portion having a side surface formed to be inclined. For example, the second semiconductor layer320′ may directly contact a parallel side surface of the active layer330′ and the inclined upper end portion of the first semiconductor layer310′. However, the second semiconductor layer320′ is not formed in the lower end portion of the first semiconductor layer310′.

The electrode layer370′ is disposed to surround an outer surface of the second semiconductor layer320′. For example, the electrode layer370′ and the second semiconductor layer320′ may be substantially a same shape. For example, the electrode layer370′ may contact the entire outer surface of the second semiconductor layer320′.

The insulating layer380′ may be disposed to surround outer surfaces of the electrode layer370′ and the first semiconductor layer310′. The insulating layer380′ may directly contact the electrode layer370′, the lower end portion of the first semiconductor layer310′, and exposed lower end portions of the active layer330′ and the second semiconductor layer320′.

In the case of the light-emitting element300′ ofFIG.15, the insulating layer380′ may include an insulating film381′ and an element dispersion agent385′ including a first functional group385a′, a ligand385p′, and a second functional group385b′ and may have a length h′. A description thereof is the same as described above.

The display device10according to an embodiment may include electrodes210and220having different shapes from those ofFIGS.2and3.

FIG.16is a schematic plan view illustrating a pixel of a display device according to another embodiment.

Referring toFIG.16, in a display device10_1according to an embodiment, each of a first electrode210_1and a second electrode220_1may further include a portion extending in the first direction DR1. The display device10_1inFIG.16is different from the display device10ofFIG.2in that shapes of the first electrode210_1and the second electrode220_1are different. Hereinafter, repetitive descriptions thereof will be omitted, and differences therefrom will be mainly provided.

In the display device10_1ofFIG.16, the first electrode210_1and the second electrode2201may respectively include electrode stem portions210S_1and220S_1extending in the first direction DR1and one or more electrode branch portions210B_1and220B_1respectively branched in the second direction DR2from the electrode stem portions210S_1and220S_1.

Specifically, the first electrode210_1may include a first electrode stem portion210S_1disposed to extend in the first direction DR1and one or more first electrode branch portions210B_1branched from the first electrode stem portion210S_1to extend in the second direction DR2.

Ends of the first electrode stem portion210S_1of a pixel may be spaced apart from each other and terminated between the sub-pixels PXn and placed substantially colinear with the first electrode stem portion210S_1of an adjacent sub-pixel PXn in a same row (e.g., which is adjacent in the first direction DR1). Since ends of each of the first electrode stem portions210S_1disposed in each sub-pixel PXn are spaced apart from each other, an electrical signal may be independently transmitted to each of the first electrode branch portions210B_1.

The first electrode branch portion210B_1is branched from at least a portion of the first electrode stem portion210S_1and disposed to extend in the second direction DR2. However, the first electrode branch portion210B_1may be terminated in a state of being spaced apart from a second electrode stem portion220S_1disposed to face the first electrode stem portion210S_1.

The second electrode220_1may include the second electrode stem portion220S_1disposed to extend in the first direction DR1and one or more second electrode branch portions220B_1branched from the second electrode stem portion220S_1to extend in the second direction DR2. The second electrode stem portion220S_1may be disposed to be spaced apart from and face the first electrode stem portion210S_1, and the second electrode branch portion220B_1may be disposed to be spaced apart from and face the one or more first electrode branch portions210B_1.

Unlike the first electrode stem portion210S_1, the second electrode stem portion220S_1may be disposed to extend in the first direction DR1to cross each of the sub-pixels PXn. The second electrode stem portion220S_1crossing each sub-pixel PXn may be electrically connected to a peripheral portion of a display area DPA, in which each of the pixels PX or sub-pixels PXn is disposed, or electrically connected to a portion extending from a non-display area NDA in a direction.

The second electrode branch portion220B_1may be branched from the second electrode stem portion220S_1in the second direction DR2, and terminated in a state of being spaced apart from the first electrode stem portion210S. Since the second electrode branch portion220B_1is disposed to be spaced apart from and face the first electrode branch portion210B_1, an area in which the light-emitting elements300are disposed may be formed between the second electrode branch portions220B_1and the first electrode branch portions210B_1.

FIG.16illustrates that two first electrode branch portions210B_1and a second electrode branch portion220B_1are disposed in a sub-pixel PXn, and the first electrode210_1is disposed in a shape surrounding an outer surface of the second electrode branch portion220B_1. However, the disclosure is not limited thereto. In the display device101, a larger or smaller number of electrode branch portions210B_1and220B_1may be disposed in each sub-pixel PXn. In this case, the first electrode branch portions210B_1and the second electrode branch portion220B_1may be alternately disposed to be spaced apart from each other.

The light-emitting elements300may be disposed between the first electrode branch portions210B_1and the second electrode branch portion220B_1, and the first contact electrode261and the second contact electrode262may be disposed on the first electrode branch portions210B_1and the second electrode branch portion220B_1, respectively. The display device10_1ofFIG.16includes a larger number of electrodes210_1and220_1or electrode branch portions210B_1and220B_1in a sub-pixel PXn, and thus a larger number of light-emitting elements300may be disposed. In addition, descriptions of the other members are the same as those described above with reference toFIGS.2and3, and thus detailed descriptions thereof will be omitted.

FIG.17is a schematic plan view illustrating a pixel of a display device according to still another embodiment.

Referring toFIG.17, a display device102according to an embodiment may include a first electrode210_2and a second electrode220_2of which at least a partial area has a curved shape, and the curved area of the first electrode2102may be spaced apart from and face the curved area of the second electrode220_2. The display device10_2inFIG.17is different from the display device10ofFIG.2in that shapes of the first electrode210_2and the second electrode220_2are different. Hereinafter, repetitive descriptions will be omitted, and differences therefrom will be mainly provided.

The first electrode210_2of the display device10_2inFIG.17may include holes HOL. As an example, as shown in the drawing, the first electrode210_2may include a first hole HOL1, a second hole HOL2, and a third hole HOL3arranged in the second direction DR2. However, the disclosure is not limited thereto, and the first electrode210_2may include a larger or smaller number of holes HOL, or only a hole HOL. Hereinafter, an example in which the first electrode210_2includes the first hole HOL1, the second hole HOL2, and the third hole HOL3will be described.

In an embodiment, the first hole HOL1, the second hole HOL2, and the third hole HOL3may each have a circular planar shape. Accordingly, the first electrode210_2may include a curved area formed by each hole HOL and may face the second electrode220_2at the curved area. However, the above description is illustrative, and the disclosure is not limited thereto. A shape of each of the first hole HOL1, the second hole HOL2, and the third hole HOL3is not limited as long as the shape can provide a space in which the second electrode2202is disposed as will be described below. For example, each of the first hole HOL1, the second hole HOL2, and the third hole HOL3may have a planar shape such as an elliptical shape or a polygonal shape with four or more angles.

Second electrodes220_2may be disposed in each sub-pixel PXn. For example, in each sub-pixel PXn, three second electrodes220_2may be disposed corresponding to the first to third holes HOL1to HOL3of the first electrode210_2. The second electrode220_2may be located in each of the first to third holes HOL1to HOL3and may be surrounded by the first electrode210_2.

In an embodiment, each of the holes HOL of the first electrode210_2may have an outer surface with a curved shape, and the second electrode2202disposed in correspondence with the hole HOL of the first electrode2102may have an outer surface with a curved shape and may be spaced apart from and face the first electrode210_2. As shown inFIG.17, the first electrode210_2includes holes HOL each having a circular shape in a plan view, and the second electrode220_2may have a circular shape in a plan view. In the first electrode210_2, a curved surface of an area in which the hole HOL is formed may be spaced apart from and face the curved outer surface of the second electrode220_2. As an example, the first electrode2102may be disposed to surround the outer surface of the second electrode220_2.

As described above, light-emitting elements300may be disposed between the first electrode210_2and the second electrode220_2. The display device10_2according to the embodiment may include the second electrode220_2having a circular shape, and the first electrode2102disposed to surround the second electrode220_2, and the light-emitting elements300may be arranged along the curved outer surface of the second electrode220_2. As described above, since each of the light-emitting elements300has a shape extending in a direction, the light-emitting elements300arranged along the curved outer surface of the second electrode220_2in each sub-pixel PXn may be disposed such that extending directions thereof are directed in different directions. Each of the sub-pixels PXn may have various emission directions according to the direction in which the extending direction of the light-emitting element300is directed. In the display device10_2according to the embodiment, each of the first electrode210_2and the second electrode220_2is disposed to have a curved shape, and thus the light-emitting elements300disposed therebetween may be disposed to be directed in different directions, so that lateral visibility of the display device10_2may be improved.