Patent Description:
Display devices become more and more important as multimedia technology evolves. Accordingly, a variety of types of display devices such as organic light-emitting display (OLED) devices and liquid-crystal display (LCD) devices are currently used.

Display devices may display images and include a display panel such as an organic light-emitting display panel or a liquid-crystal display panel. Among display panel types, light-emitting display panels may include light-emitting elements, such as light-emitting diodes. For example, light-emitting diodes (LEDs) may include an organic light-emitting diode (OLED) using an organic material as a fluorescent material, and an inorganic light-emitting diode using an inorganic material as a fluorescent material. <CIT> discloses a light-emitting element solvent, a photodegradable thickener, a light-emitting element ink and a method for manufacturing a display device. The method for manufacturing a display device comprises the steps of: spraying, on a target substrate having a first electrode and a second electrode formed thereon, an element ink comprising a first element solvent and a light-emitting element dispersed in the first element solvent; forming a second element solvent in which at least a partial bond of the first element solvent is decomposed by irradiating light to the first element solvent, and mounting the light-emitting element on the first electrode and the second electrode; and removing the second element solvent. <CIT> discloses a light emitting device that includes: a substrate; a light emitting element on the substrate, the light emitting element having a first end portion and a second end portion arranged in a longitudinal direction; one or more partition walls disposed on the substrate, the one or more partition walls being spaced apart from the light emitting element; a first reflection electrode adjacent the first end portion of the light emitting element; a second reflection electrode adjacent the second end portion of the light emitting element; a first contact electrode connected to the first reflection electrode and the first end portion of the light emitting element; an insulating layer on the first contact electrode, the insulating layer having an opening exposing the second end portion of the light emitting element and the second reflection electrode to the outside; and a second contact electrode on the insulating layer. According to its abstract, <CIT> describes a display device that may include a pixel disposed in a display area. The pixel may include: first and second electrodes; a light emitting element disposed between the first and second electrodes; a first insulating pattern disposed on the light emitting element such that first and second ends of the light emitting element are exposed; a second insulating pattern disposed on the first insulating pattern such that opposite ends of the first insulating pattern are exposed; a third insulating pattern disposed on the second insulating pattern to cover opposite ends of the second insulating pattern; a first contact electrode disposed on the first end of the light emitting element, and electrically connecting the first end to the first electrode; and a second contact electrode disposed on the second end of the light emitting element, and electrically connecting the second end to the second electrode.

Aspects of the disclosure provide a display device that can prevent the aligned light-emitting elements from being detached.

It should be noted that aspects of the disclosure are not limited to the above. Additional aspects will be apparent to those skilled in the art from the following descriptions.

According to embodiments of the disclosure, a first organic insulating layer and a second organic insulating layer are disposed on and under light-emitting elements, respectively, so that the light-emitting elements can be adhered and fixed to a first passivation layer. In this manner, it may be possible to prevent the light-emitting elements from being detached during a cleaning process performed after the light-emitting elements have been aligned.

According to an embodiment of the disclosure, a first organic insulating layer, a second organic insulating layer in the display device are made of an organic material. The first organic insulating layer and the second organic insulating layer can be patterned via a single etching process, thereby simplifying the processes.

It should be noted that effects of the disclosure are not limited to those described above and other effects of the disclosure will be apparent to those skilled in the art from the following descriptions.

According to an embodiment of invention, a display device according to claim <NUM> is defined.

In an embodiment, the first organic insulating layer may overlap the at least one light-emitting element, and a planar size of the first organic insulating layer may be larger than a planar size of the at least one light-emitting element.

In an embodiment, the first organic insulating layer may overlap the at least one light-emitting element in the direction.

In an embodiment, the first organic insulating layer may extend to the first passivation layer and the at least one light-emitting element.

In an embodiment, the at least one light-emitting element may be spaced apart from the first passivation layer.

In an embodiment, at least a portion of the at least one light-emitting element extends to the first passivation layer, and another portion of the at least one light-emitting element extends to the first organic insulating layer.

In an embodiment, the second organic insulating layer may overlap the first organic insulating layer and the at least one light-emitting element, and may extend to the at least one light-emitting element, the second organic insulating layer may continuously overlap the at least one light-emitting element in the direction.

In an embodiment, a width of portions of the first organic insulating layer that overlap the at least one light-emitting element may be larger than a width of the second organic insulating layer in a longitudinal direction of the at least one light-emitting element.

In an embodiment, the display device may further comprise a second passivation layer disposed on the second organic insulating layer, wherein the second organic insulating layer and the second passivation layer overlap each other and have a same size.

In an embodiment, the first organic insulating layer and the second organic insulating layer may be made of a same material.

In the invention, the display device further comprises a first contact electrode disposed on the first electrode and electrically contacting a first end of the at least one light-emitting element, a second contact electrode disposed on the second electrode and electrically contacting a second end of the at least one light-emitting element, and a second passivation layer disposed on the second organic insulating layer, wherein the first contact electrode is in direct contact with an end of each of the second organic insulating layer and the second passivation layer, the second contact electrode is in direct contact with another end of each of the second organic insulating layer and the second passivation layer, and the first contact electrode and the second contact electrode are not in contact with an upper surface of the second passivation layer.

The above and other aspects and features of the disclosure will become more apparent by describing in detail embodiments thereof with reference to the attached drawings, in which:.

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

As used herein, the singular forms, "a," "an," and "the" are intended to include the plural forms as well (and vice versa), unless the context clearly indicates otherwise. In the specification and the claims, the term "and/or" is intended to include any combination of the terms "and" and "or" for the purpose of its meaning and interpretation. For example, "A and/or B" may be understood to mean "A, B, or A and B. " The terms "and" and "or" may be used in the conjunctive or disjunctive sense and may be understood to be equivalent to "and/or. " The phrase "at least one of" is intended to include the meaning of "at least one selected from the group of" for the purpose of its meaning and interpretation. For example, "at least one of A and B" may be understood to mean "A, B, or A and B.

It will also be understood that when a feature (e.g., layer) is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening features may also be present. The same reference numbers indicate the same components throughout the specification.

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

The spatially relative terms "below", "beneath", "lower", "above", "upper", or the like, may be used herein for ease of description to describe the relationship between one element or component and another element or component as illustrated in the drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, in the case where a device illustrated in the drawing is turned over, the device positioned "below" or "beneath" another device may be placed "above" another device. Accordingly, the illustrative term "below" may include both the lower and upper positions. The device may also be oriented in other directions and thus the spatially relative terms may be interpreted differently depending on the orientations.

It will be understood that the terms "connected to" or "coupled to" may include a physical or electrical connection or coupling.

The terms "overlap" or "overlapped" mean that a first object may be above or below or to a side of a second object, and vice versa. Additionally, the term "overlap" may include layer, stack, face or facing, extending over, covering, or partly covering or any other suitable term as would be appreciated and understood by those of ordinary skill in the art. When an element is described as 'not overlapping' or 'to not overlap' another element, this may include that the elements are spaced apart from each other, offset from each other, or set aside from each other or any other suitable term as would be appreciated and understood by those of ordinary skill in the art.

The terms "comprises," "comprising," "includes," and/or "including,", "has," "have," and/or "having," and variations thereof when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Each of the features of the various embodiments of the disclosure may be combined or combined with each other, in part or in whole. Each embodiment may be implemented independently of each other or may be implemented together in an association.

Terms such as "about", "approximately", and "substantially" as used herein are inclusive of the stated value and may mean within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system).

Unless otherwise defined or implied, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains.

<FIG> is a plan view schematically showing a display device according to an embodiment of the disclosure.

Referring to <FIG>, the display device <NUM> may display a moving image or a still image. The display device <NUM> may refer to any electronic device that provides a display screen. For example, the display device <NUM> may include a television set, a laptop computer, a monitor, an electronic billboard, an Internet of Things devices, a mobile phone, a smart phone, a tablet personal computer (PC), an electronic watch, a smart watch, a watch phone, a head-mounted display device, a mobile communications terminal, an electronic notebook, an electronic book, a portable multimedia player (PMP), a navigation device, a game console, a digital camera, a camcorder, etc..

The display device <NUM> may include a display panel for providing a display screen. Examples of the display panel may include an inorganic light-emitting diode display panel, an organic light-emitting display panel, a quantum-dot light-emitting display panel, a plasma display panel, a field emission display panel, etc. In the following description, an inorganic light-emitting diode display panel may be employed as an example of the display panel <NUM>, but the disclosure is not limited thereto. Any other display panel may be employed as long as technical ideas of the disclosure can be equally applied.

The shape of the display device <NUM> may be modified in a variety of ways. For example, the display device <NUM> may have shapes such as a rectangle with longer lateral sides, a rectangle with longer vertical sides, a square, a quadrangle with rounded corners (vertices), other polygons, a circle, etc. The shape of a display area DPA of the display device <NUM> may also be similar to the overall shape of the display device <NUM>. <FIG> shows the display device <NUM> in the shape of a rectangle with longer horizontal sides and the display area DPA.

The display device <NUM> may include the display area DPA and a non-display area NDA. In the display area DPA, images can be displayed. In the non-display area NDA, images may not be displayed. The display area DPA may be referred to as an active area, while the non-display area NDA may be referred to as an inactive area. The display area DPA may generally occupy a center of the display device <NUM>.

The display area DPA may include pixels PX. The pixels PX may be arranged in a matrix. The shape of each pixel PX may be, but is not limited to, a rectangle or a square when viewed from the top. Each pixel may have a diamond shape having sides inclined with respect to a direction. The pixels PX may be arranged in stripes and a PenTile® pattern alternately. Each of the pixels PX may include at least one light-emitting element <NUM> that emits light of a particular wavelength band to represent a color.

The non-display area NDA may be disposed adjacent to (e.g., around) the display area DPA. The non-display area NDA may surround the display area DPA entirely or partially. The display area DPA may have a rectangular shape, and the non-display area NDA may be disposed to be adjacent to the four sides of the display area DPA. The non-display area NDA may form a bezel of the display device <NUM>. Lines or circuit drivers included in the display device <NUM> may be disposed in each of the non-display area NDA, or external devices may be mounted.

<FIG> is a plan view schematically showing a pixel of a display device according to an embodiment of the disclosure.

Referring to <FIG>, each of the pixels PX may include sub-pixels PXn, where n may be an integer from one to three. For example, a pixel PX may include a first sub-pixel PX1, a second sub-pixel PX2 and a third sub-pixel PX3. The first sub-pixel PX1 may emit light of a first color, the second sub-pixel PX2 may emit light of a second color, and the third sub-pixel PX3 may emit light of a third color. For example, the first color may be blue, the second color may be green, and the third color may be red. It is, however, to be understood that the disclosure is not limited thereto. All the sub-pixels PXn may emit light of the same color. Although the pixel PX includes three sub-pixels PXn in the example shown in <FIG>, the disclosure is not limited thereto. The pixel PX may include more than two sub-pixels PXn.

Each of the sub-pixels PXn of the display device <NUM> may include an emission area EMA and a non-emission area. In the emission area EMA, the light-emitting elements <NUM> are disposed to emit light of a particular wavelength. In the non-emission area, no light-emitting element <NUM> may be disposed and light emitted from the light-emitting elements <NUM> may not reach and thus no light exits therefrom. The emission area includes an area in which the light-emitting elements <NUM> are disposed, and includes an area adjacent to the light-emitting elements <NUM> where light emitted from the light-emitting elements <NUM> exits.

It is, however, to be understood that the disclosure is not limited thereto. The emission area EMA may also include an area in which light emitted from the light-emitting elements <NUM> may be reflected or refracted by other elements to exit. The light-emitting elements <NUM> may be disposed in each of the sub-pixels PXn, and the emission area EMA may include the area where the light-emitting elements are disposed and the adjacent area.

Each of the sub-pixels PXn may further include a cut area CBA disposed in the non-emission area. The cut area CBA may be disposed on a side of the emission area EMA in the second direction DR2. The cut area CBA may be disposed between the emission areas EMA of neighboring sub-pixels PXn in the second direction DR2. In the display area DPA of the display device <NUM>, emission areas EMA and cutout areas CBA may be arranged. For example, the emission areas EMA and the cutout areas CBA may be arranged repeatedly in the first direction DR1, and may be arranged alternately in the second direction DR2. The spacing between the cutout areas CBA in the first direction DR1 may be smaller than the spacing between the emission areas EMA in the first direction DR1. A second bank BNL2 may be disposed between the cutout regions CBA and the emission areas EMA, and the distance between them may vary depending on the width of the second bank BNL2. Although the light-emitting elements <NUM> may not be disposed in the cutout areas CBA and thus no light may exit therefrom, parts of the electrodes <NUM> and <NUM> disposed in each of the sub-pixels PXn may be disposed in the cutout areas CBA. The electrodes <NUM> and <NUM> disposed for each of the sub-pixels PXn may be disposed separately from each other in the cut area CBA.

<FIG> is a schematic cross-sectional view taken along lines Q1-Q1', Q2-Q2' and Q3-Q3' of <FIG>. <FIG> is a view showing a cross section from one end to the other end of the light-emitting element <NUM> disposed in the first sub-pixel PX1 of <FIG>.

Referring to <FIG> in conjunction with <FIG>, the display device <NUM> includes a first substrate <NUM>, a semiconductor layer disposed on the first substrate <NUM>, conductive layers, and insulating layers. The semiconductor layer, the conductive layers and the insulating layers may form a circuit layer and an emission layer of the display device <NUM>.

Specifically, the first substrate <NUM> may be an insulating substrate. The first substrate <NUM> may be made of an insulating material such as glass, quartz, a polymer resin, or a combination thereof. The first substrate <NUM> may be either a rigid substrate or a flexible substrate that can be bent, folded, and/or rolled.

The light-blocking layer BML may be disposed on the first substrate <NUM>. The light-blocking layer BML may overlap an active layer ACT of a first transistor T1 of the display device <NUM>. The light-blocking layer BML may include a material that blocks light, and thus can prevent light from entering the active layer ACT of the first transistor T1. For example, the light-blocking layer BML may be formed of an opaque metal material that blocks light transmission. It is, however, to be understood that the disclosure is not limited thereto. In some embodiments, the light-blocking layer BML may be eliminated.

The buffer layer <NUM> may be disposed on (e.g., entirely on) the first substrate <NUM>, including the light-blocking layer BML. The buffer layer <NUM> may be formed on the first substrate <NUM> to protect the first thin-film transistors T1 of the pixels PX from moisture permeating through the first substrate <NUM> that may be susceptible to moisture permeation, and may also provide a flat surface. The buffer layer <NUM> may be formed of inorganic layers stacked on one another alternately. For example, the buffer layer <NUM> may be made up of multiple layers in which inorganic layers including at least one of a silicon oxide (SiOx), a silicon nitride (SiNx) and silicon oxynitride (SiOxNy) may be stacked on one another alternately.

The semiconductor layer may be disposed on the buffer layer <NUM>. The semiconductor layer may include the active layer ACT of the first transistor T1. These may be disposed to partially overlap a gate electrode G1 of a first gate conductive layer, etc., which will be described later.

Although only the first transistor T1 among the transistors included in the sub-pixels PXn of the display device <NUM> is depicted in the drawing, the disclosure is not limited thereto. The display device <NUM> may include a larger number of transistors. For example, the display device <NUM> may include one or more transistors in addition to the first transistor T1, e.g., two or three transistors in each of the sub-pixels PXn.

The semiconductor layer may include polycrystalline silicon, monocrystalline silicon, an oxide semiconductor, etc., or a combination thereof. In the case that the semiconductor layer includes an oxide semiconductor, each active layer ACT may include conductive regions ACT_a and ACT_b and a channel region ACT_c therebetween. The oxide semiconductor may be an oxide semiconductor including indium (In). For example, the oxide semiconductor may be indium-tin oxide (ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-zinc-tin oxide (IZTO), indium-gallium-tin oxide (IGTO), indium-gallium-zinc oxide (IGZO), indium-gallium-zinc-tin oxide (IGZTO), etc..

In other embodiments, the semiconductor layer may include polycrystalline silicon. The polycrystalline silicon may be formed by crystallizing amorphous silicon, and the conductive regions of the active layer ACT may be doped regions doped with impurities.

The first gate insulating layer <NUM> may be disposed on the semiconductor layer and the buffer layer <NUM>. The first gate insulating layer <NUM> may include a semiconductor layer, and may be disposed on the buffer layer <NUM>. The first gate insulating layer <NUM> may work as a gate insulator of each of the thin-film transistors. The first gate insulating layer <NUM> may be formed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx) and silicon oxynitride (SiOxNy), or may be formed of a stack of the materials.

The first gate conductive layer may be disposed on the first gate insulating layer <NUM>. The first gate conductive layer may include the gate electrode G1 of the first transistor T1 and a first capacitor electrode CSE1 of a storage capacitor. The gate electrode G1 may be disposed so that it overlaps the channel region ACT_c of the active layer ACT in the thickness direction. The first capacitor electrode CSE1 may be disposed so that it overlaps a second capacitor electrode CSE2 (described later) in the thickness direction. According to an embodiment of the disclosure, the first capacitor electrode CSE1 may be integrated with the gate electrode G1. The first capacitor electrode CSE1 may be disposed so that it overlaps the second capacitor electrode CSE2 in the thickness direction, and the storage capacitor may be formed between them.

The first gate conductive layer may be made up of a single layer or multiple layers of molybdenum (Mo), aluminium (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloy thereof. It is, however, to be understood that the disclosure is not limited thereto.

The first interlayer dielectric layer <NUM> may be disposed on the first gate conductive layer. The first interlayer dielectric layer <NUM> may serve as an insulating layer between the first gate conductive layer and other layers disposed thereon. The first interlayer dielectric layer <NUM> may be disposed so that it overlaps (e.g., covers) the first gate conductive layer for protection. The first interlayer dielectric layer <NUM> may be formed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx) and silicon oxynitride (SiOxNy), or may be formed of a stack of the materials.

The first data conductive layer may be disposed on the first interlayer dielectric layer <NUM>. The first data conductive layer may include a first source electrode S1 and a first drain electrode D1 of the first transistor T1, a data line DTL, and a second capacitor electrode CSE2.

The first source electrode S1 and the first drain electrode D1 of the first transistor T1 may be in contact with the doped regions ACT_a and ACT_b of the active layer ACT, respectively, through the contact holes penetrating through the first interlayer dielectric layer <NUM> and the first gate insulating layer <NUM>. The first source electrode S1 of the first transistor T1 may be electrically connected to the light-blocking layer BML through another contact hole.

The data line DTL may apply a data signal to another transistor (not shown) included in the display device <NUM>. Although not shown in the drawings, the data line DTL may be connected to the source/drain electrodes of another transistor to transfer a signal applied from the data line DTL.

The second capacitor electrode CSE2 may be disposed to overlap the first capacitor electrode CSE1 in the thickness direction. According to an embodiment of the disclosure, the second capacitor electrode CSE2 may be integrally connected to the first source electrode S1.

The first data conductive layer may be made up of a single layer or multiple layers of molybdenum (Mo), aluminium (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloy thereof. It is, however, to be understood that the disclosure is not limited thereto.

The second interlayer dielectric layer <NUM> may be disposed on the first data conductive layer. The second interlayer dielectric layer <NUM> may serve as an insulating layer between the first data conductive layer and other layers disposed thereon. The second interlayer dielectric layer <NUM> may cover the first data conductive layer to protect it. The second interlayer dielectric layer <NUM> may be formed of an inorganic layer including an inorganic material, such as silicon oxide (SiOx), silicon nitride (SiNx) and silicon oxynitride (SiOxNy), or may be formed of a stack of the materials.

The second data conductive layer may be disposed on the second interlayer dielectric layer <NUM>. The second data conductive layer may include a first voltage line VL1, a second voltage line VL2, and a first conductive pattern CDP. A high-level voltage (or a first supply voltage) may be applied to the first voltage line VL1 to be supplied to the first transistor T1, and a low-level voltage (or a second supply voltage) may be applied to the second voltage line VL2 to be supplied to the second electrode <NUM>. An alignment signal that may be necessary for aligning the light-emitting elements <NUM> during the process of fabricating the display device <NUM> may be applied to the second voltage line VL2.

The first conductive pattern CDP may be connected to the second capacitor electrode CSE2 through a contact hole formed in the second interlayer dielectric layer <NUM>. The second capacitor electrode CSE2 may be integrated with the first source electrode S1 of the first transistor T1, and the first conductive pattern CDP may be electrically connected to the first source electrode S1. The first conductive pattern CDP may also come in contact with the first electrode <NUM> to be described later. The first transistor T1 may transfer the first supply voltage applied from the first voltage line VL1 to the first electrode <NUM> through the first conductive pattern CDP. Although the second data conductive layer includes one second voltage line VL2 and one first voltage line VL1 in the example shown in the drawings, the disclosure is not limited thereto. The second data conductive layer may include more than one first voltage line VL1 and second voltage line VL2.

The second data conductive layer may be made up of a single layer or multiple layers of molybdenum (Mo), aluminium (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd) and copper (Cu) or an alloy thereof. It is, however, to be understood that the disclosure is not limited thereto.

The first planarization layer <NUM> may be disposed on the second data conductive layer. The first planarization layer <NUM> may include an organic insulating material, e.g., an organic material such as polyimide (PI), to provide a flat surface.

On the first planarization layer <NUM>, first banks BNL1, electrodes <NUM> and <NUM>, light-emitting elements <NUM>, contact electrodes CNE1 and CNE2, and a second bank BNL2 are disposed. Insulating layers PAS1 and PAS2 are disposed on the first planarization layer <NUM>.

The first banks BNL1 may be disposed directly on the first planarization layer <NUM>. The first banks BNL1 may have a shape extended in the second direction DR2 within each of the sub-pixels PXn, and may not be extended to an adjacent sub-pixel PXn in the second direction DR2. They may be disposed in the emission area EMA. The first banks BNL1 may be spaced apart from each other in the first direction DR1, and the light-emitting elements <NUM> may be disposed therebetween. The first banks BNL1 may be disposed in each of the sub-pixels PXn to form a linear pattern in the display area DPA of the display device <NUM>. Although two first banks BNL1 are shown in the drawings, the disclosure is not limited thereto. More than two first banks BNL1 may be disposed depending on the number of electrodes <NUM> and <NUM>.

The first banks BNL1 may have a structure that at least partly protrudes from the upper surface of the first planarization layer <NUM>. The protrusions of the first banks BNL1 may have inclined side surfaces. The light emitted from the light-emitting elements <NUM> may be reflected by the electrodes <NUM> and <NUM> disposed on the first banks BNL1 so that the light may exit toward the upper side of the first planarization layer <NUM>. The first banks BNL1 may provide the area in which the light-emitting element <NUM> may be disposed and may also serve as reflective partition walls that reflect light emitted from the light-emitting element <NUM> upward. The side surfaces of the first banks BNL1 may be inclined in a linear shape, but the disclosure is not limited thereto. The first banks BNL1 may have a semicircle or semi-ellipse shape with a curved outer surface. The first banks BNL1 may include, but are not limited to, an organic insulating material such as polyimide (PI).

The electrodes <NUM> and <NUM> may be disposed on the first banks BNL1 and the first planarization layer <NUM>. The electrodes <NUM> and <NUM> include the first electrode <NUM> and the second electrode <NUM>. The electrodes <NUM> and <NUM> are extended in the second direction DR2 and may be spaced apart from each other in the first direction DR1.

The first electrode <NUM> and the second electrode <NUM> are extended in the second direction DR2 in each of the sub-pixels PXn, and they may be spaced apart from other electrodes <NUM> and <NUM> in the cut area CBA. For example, the cut area CBA may be disposed between the emission areas EMA of the neighboring sub-pixels PXn in the second direction DR2, and the first electrode <NUM> and the second electrode <NUM> may be separated from other first electrodes <NUM> and second electrodes <NUM> disposed in an adjacent sub-pixel PXn in the second direction DR2 in the cut area CBA. It is, however, to be understood that the disclosure is not limited thereto. Some electrodes <NUM> and <NUM> may not be separated for each of the sub-pixels PXn but may be extended and disposed across adjacent sub-pixels PXn in the second direction DR2. In other embodiments, only one of the first electrode <NUM> and the second electrode <NUM> may be separated.

The first electrode <NUM> may be electrically connected to the first transistor T1 through a first contact hole CT1, and the second electrode <NUM> may be electrically connected to the second voltage line VL2 through a second contact hole CT2. For example, an extended portion of the first electrode <NUM> in the first direction DR1 of the second bank BNL2 may be in contact with the first conductive pattern CDP through the first contact hole CT1 penetrating through the first planarization layer <NUM>. An extended portion of the second electrode <NUM> in the first direction DR1 of the second bank BNL2 may be in contact with the second voltage line VL2 through the second contact hole CT2 penetrating through the first planarization layer <NUM>. It is, however, to be understood that the disclosure is not limited thereto. According to another embodiment, the first contact hole CT1 and the second contact hole CT2 may be formed in the emission area EMA surrounded by the second bank BNL2 so that they do not overlap the second bank BNL2.

Although one first electrode <NUM> and one second electrode <NUM> are disposed for each of the sub-pixels PXn in the drawings, the disclosure is not limited thereto. More than one first electrode <NUM> and more than one second electrode <NUM> may be disposed in each of the sub-pixels PXn.

The first electrode <NUM> and the second electrode <NUM> may be disposed directly on the first banks BNL1, respectively. The first electrode <NUM> and the second electrode <NUM> may have a larger width than the first banks BNL1. For example, the first electrode <NUM> and the second electrode <NUM> may be disposed to cover the outer surfaces of the first banks BNL1. The first electrode <NUM> and the second electrode <NUM> may be respectively disposed on the side surfaces of the first banks BNL1, and the distance between the first electrode <NUM> and the second electrode <NUM> may be smaller than the distance between the first banks BNL1. At least a portion of the first electrode <NUM> and the second electrode <NUM> may be disposed directly on the first planarization layer <NUM> so that they may be located on the same plane. It is, however, to be understood that the disclosure is not limited thereto. In some embodiments, the electrodes <NUM> and <NUM> may have a width smaller than that of the first banks BNL1. It is to be noted that the electrodes <NUM> and <NUM> may be disposed to cover at least one side surface of the first banks BNL1 to reflect light emitted from the light-emitting element <NUM>.

Each of the electrodes <NUM> and <NUM> may include a conductive material having a high reflectance. For example, each of the electrodes <NUM> and <NUM> may include at least one metal such as silver (Ag), copper (Cu) and aluminium (Al) as the material having a high reflectance, and may be an alloy including aluminium (Al), nickel (Ni), lanthanum (La), etc. Each of the electrodes <NUM> and <NUM> may reflect light that may be emitted from the light-emitting element <NUM> and travel toward the side surfaces of the first banks BNL1 toward the upper side of each of the sub-pixels PXn.

It is, however, to be understood that the disclosure is not limited thereto. Each of the electrodes <NUM> and <NUM> may further include a transparent conductive material. For example, each of the electrodes <NUM> and <NUM> may include a material such as indium tin oxide (ITO), indium zinc oxide (IZO) and indium tin zinc oxide (ITZO). In some embodiments, each of the electrodes <NUM> and <NUM> may have a structure in which one or more layers of a transparent conductive material and a metal layer having high reflectivity may be stacked, or may be made up of a single layer. For example, each of the electrodes <NUM> and <NUM> may have a stack structure such as ITO/silver (Ag)/ITO/, ITO/Ag/IZO, or ITO/Ag/ITZO/IZO.

The electrodes <NUM> and <NUM> are electrically connected to the light-emitting elements <NUM>, and a voltage may be applied so that the light-emitting elements <NUM> can emit light. The electrodes <NUM> and <NUM> are electrically connected to the light-emitting element <NUM> through the contact electrodes CNE1 and CNE2, and may transfer electrical signals applied thereto to the light-emitting element <NUM> through the contact electrodes CNE1 and CNE2.

The first electrode <NUM> or the second electrode <NUM> may be electrically connected to an anode electrode of the light-emitting element <NUM>, while another may be electrically connected to a cathode electrode of the light-emitting element <NUM>. It is, however, to be understood that the disclosure is not limited thereto.

The electrodes <NUM> and <NUM> may be utilized to form an electric field within the sub-pixel PXn to align the light-emitting elements <NUM>. The light-emitting elements <NUM> may be disposed between the first electrode <NUM> and the second electrode <NUM> by an electric field formed on the first electrode <NUM> and the second electrode <NUM>. The light-emitting elements <NUM> of the display device <NUM> may be sprayed on the electrodes <NUM> and <NUM> via an inkjet printing process. In the case that droplets of the ink including the light-emitting elements <NUM> are ejected onto the electrodes <NUM> and <NUM>, an alignment signal may be applied to the electrodes <NUM> and <NUM> to generate an electric field. The light-emitting elements <NUM> dispersed in the ink may be aligned on the electrodes <NUM> and <NUM> by receiving the electrophoretic force by the electric field generated over the electrodes <NUM> and <NUM>.

The first passivation layer PAS1 is disposed on the first planarization layer <NUM>. The first passivation layer PAS1 may be disposed to cover the first banks BNL1 and the first electrode <NUM> and the second electrode <NUM>. The first passivation layer PAS1 can protect the first electrode <NUM> and the second electrode <NUM> and insulate the first and second electrodes <NUM>, <NUM> from each other. The first passivation layer PAS1 can prevent that the light-emitting element <NUM> disposed on the first passivation layer PAS1 may be brought into contact with other elements and damaged.

According to an embodiment of the disclosure, the first passivation layer PAS1 may include openings OP partially exposing the first electrode <NUM> and the second electrode <NUM>. The openings OP may partially expose portions of the electrodes <NUM> and <NUM> disposed on the upper surface of the first banks BNL1. Portions of the contact electrodes CNE1 and CNE2 may be in contact with the electrodes <NUM> and <NUM> exposed through the openings OP, respectively.

The second bank BNL2 may be disposed on the first passivation layer PAS1. The second bank BNL2 may be disposed in a lattice pattern on the surface (e.g., entire surface) of the display area DPA including portions extended in the first direction DR1 and the second direction DR2 when viewed from the top. The second bank BNL2 may be disposed along the border of each of the sub-pixels PXn to distinguish adjacent sub-pixels PXn from one another.

The second bank BNL2 may be disposed to surround the emission area EMA and the cut area CBA disposed in each of the sub-pixels PXn to distinguish such features. The first electrode <NUM> and the second electrode <NUM> are extended in the second direction DR2 and may be disposed across a portion of the second bank BNL2 that may be extended in the first direction DR1. The portion of the second bank BNL2 extended in the second direction DR2 may have a larger width between the emission areas EMA than between the cut areas CBA. Accordingly, the distance between the cut areas CBA may be smaller than the distance between the emission areas EMA.

The second bank BNL2 may have a height greater than a height of the first banks BNL1. The second bank BNL2 can prevent the ink in which different light-emitting elements <NUM> may be dispersed from overflowing to adjacent sub-pixels PXn during the inkjet printing process of the processes of fabricating the display device <NUM>, so that different sub-pixels PXn can be separated from one another and the ink may not be mixed. The second bank BNL2 may include, but is not limited to, polyimide (PI), like the first banks BNL1.

The light-emitting elements <NUM> may be disposed on the first passivation layer PAS1. The light-emitting elements <NUM> may be spaced apart from one another in the second direction DR2 in which the electrodes <NUM> and <NUM> may be extended, and may be aligned substantially parallel to one another. The light-emitting elements <NUM> may have a shape extended in one direction. The direction in which the electrodes <NUM> and <NUM> may be extended may be substantially perpendicular to the direction in which the light-emitting elements <NUM> may be extended. It is, however, to be understood that the disclosure is not limited thereto. The light-emitting elements <NUM> may be oriented obliquely to the direction in which the electrodes <NUM> and <NUM> may be extended, rather than being perpendicular thereto.

The light-emitting elements <NUM> disposed in each of the sub-pixels PXn may include an emissive layer <NUM> (see <FIG>) including different materials and may emit lights with different wavelength ranges to the outside. Accordingly, lights of the first color, the second color and the third color may exit from the first sub-pixel PX1, the second sub-pixel PX2 and the third sub-pixel PX3, respectively. It is, however, to be understood that the disclosure is not limited thereto. The sub-pixels PXn may include the same kind of light-emitting elements <NUM> and may emit light of substantially the same color.

Ends of the elements <NUM> are disposed on the electrodes <NUM> and <NUM> between the first banks BNL1. The length of the light-emitting elements <NUM> are larger than the distance between the first electrode <NUM> and the second electrode <NUM>, and the ends of the light-emitting elements <NUM> are disposed on the first electrode <NUM> and the second electrode <NUM>, respectively. For example, a first end of each of the light-emitting elements <NUM> may be located on the first electrode <NUM>, while a second other end thereof may be located on the second electrode <NUM>.

Multiple layers of the light-emitting elements <NUM> may be disposed in the direction perpendicular to the upper surface of the first substrate <NUM> or the first planarization layer <NUM>. The light-emitting elements <NUM> may be arranged such that an extending direction may be parallel to the upper surface of the first planarization layer <NUM>, and semiconductor layers included in the light-emitting elements <NUM> may be disposed sequentially in the direction parallel to the upper surface of the first planarization layer <NUM>. It is, however, to be understood that the disclosure is not limited thereto. In the case that the light-emitting elements <NUM> have a different structure, semiconductor layers may be arranged in the direction perpendicular to the upper surface of the first planarization layer <NUM>.

Ends of each of the light-emitting elements <NUM> are in contact with the contact electrodes CNE1 and CNE2, respectively. For example, a portion of semiconductor layers <NUM> and <NUM> (see <FIG>) or an electrode layer <NUM> (see <FIG>) of the light-emitting element <NUM> may be exposed because an insulating film <NUM> (see <FIG>) may not be formed at the end surfaces on the sides of the extending direction, and the exposed portion of the semiconductor layers <NUM> and <NUM> or the electrode layer <NUM> may be in contact with the contact electrodes CNE1 and CNE2. It is, however, to be understood that the disclosure is not limited thereto. At least a portion of the insulating film <NUM> may be removed so that both end surfaces of the semiconductor layers <NUM> and <NUM> of the light-emitting element <NUM> may be partially exposed (see <FIG>). The exposed side surfaces of the semiconductor layers <NUM> and <NUM> (see <FIG>) may be in contact with the contact electrodes CNE1 and CNE2.

The second passivation layer PAS2 may be partially disposed on the light-emitting elements <NUM>. For example, the second passivation layer PAS2 may have a width smaller than the length of the light-emitting elements <NUM> and may be disposed on the light-emitting elements <NUM> so that both ends of the light-emitting elements <NUM> may be exposed while being surrounded by the second passivation layer PAS2. The second passivation layer PAS2 may be disposed to cover the light-emitting elements <NUM>, the electrodes <NUM> and <NUM> and the first passivation layer PAS1 and may be removed so that both ends of the light-emitting elements <NUM> may be exposed during the process of fabricating the display device <NUM>. The second passivation layer PAS2 may be extended in the second direction DR2 on the first passivation layer PAS1 when viewed from the top, thereby forming a linear or island-like pattern in each of the sub-pixels PXn. The second passivation layer PAS2 can protect the light-emitting elements <NUM> and fix the light-emitting element <NUM> during the process of fabricating the display device <NUM>.

The contact electrodes CNE1 and CNE2 are disposed on the first passivation layer PAS1 and the light-emitting elements <NUM>.

The contact electrodes CNE1 and CNE2 have a shape extended in one direction and are disposed on the electrodes <NUM> and <NUM>. The contact electrodes CNE1 and CNE2 include a first contact electrode CNE1 disposed on the first electrode <NUM> and a second contact electrode CNE2 disposed on the second electrode <NUM>. The contact electrodes CNE1 and CNE2 may be disposed spaced apart from each other or facing each other. For example, the first contact electrode CNE1 and the second contact electrode CNE2 may be disposed on the first electrode <NUM> and the second electrode <NUM>, respectively, and may be spaced apart from each other in the first direction DR1. The contact electrodes CNE1 and CNE2 may form a stripe pattern in the emission area EMA of each of the sub-pixels PXn.

Each of the contact electrodes CNE1 and CNE2 are in contact with the light-emitting elements <NUM>. The first contact electrode CNE1 may be in contact with the first end of each of the light-emitting elements <NUM>, and the second contact electrode CNE2 may be in contact with the second end of each of the light-emitting elements <NUM>. The semiconductor layers may be exposed at both end surfaces of the light-emitting elements <NUM> in the extended direction, and the contact electrodes CNE1 and CNE2 may be in electrical contact with the semiconductor layers and may be electrically connected thereto. The first contact electrode CNE1 may be in contact with the first electrode <NUM> through an opening OP exposing a portion of the upper surface of the first electrode <NUM>, and the second contact electrode CNE2 may be in contact with the second electrode through an opening OP exposing a portion of the upper surface of the second electrode <NUM>.

The width of the contact electrodes CNE1 and CNE2 that may be measured in a direction may be smaller than the width of the electrodes <NUM> and <NUM> that may be measured in the direction. The contact electrodes CNE1 and CNE2 are in contact with first ends and second ends of the light-emitting elements <NUM> and may cover a portion of the upper surface of each of the first electrode <NUM> and the second electrode <NUM>. It is, however, to be understood that the disclosure is not limited thereto. The width of the contact electrodes CNE1 and CNE2 may be larger than that of the electrodes <NUM> and <NUM> to cover both sides of the electrodes <NUM> and <NUM>.

The contact electrodes CNE1 and CNE2 may include a transparent, conductive material. For example, the contact electrodes may include ITO, IZO, ITZO, aluminium (Al), etc., or a combination thereof. Light emitted from the light-emitting elements <NUM> may pass through the contact electrodes CNE1 and CNE2 and travel toward the electrodes <NUM> and <NUM>. It is, however, to be understood that the disclosure is not limited thereto.

Although the two contact electrodes CNE1 and CNE2 may be disposed in one sub-pixel PXn in the drawings, the disclosure is not limited thereto. The number of the contact electrodes CNE1 and CNE2 may vary depending on the number of electrodes <NUM> and <NUM> disposed for each of the sub-pixels PXn.

The above-described first passivation layer PAS1 may include an inorganic insulating material or an organic insulating material. For example, the first passivation layer PAS1 may include an inorganic insulating material such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminium oxide (Al<NUM>O<NUM>) aluminium nitride (AlN), or a combination thereof. In other embodiments, the first passivation layer PAS1 may include, as an organic insulating material, an acrylic-based resin, an epoxy-based resin, a phenol-based resin, a polyamide resin, a polyimide 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, a polymethyl methacrylate-polycarbonate synthetic resin, etc., or a combination thereof. It is, however, to be understood that the disclosure is not limited thereto.

The second passivation layer PAS2 may include an organic insulating material. In the case that the second passivation layer PAS2 is made of an organic insulating material, it may be necessary to perform a process of cleaning the first substrate <NUM> after the light-emitting elements <NUM> have been aligned and before the organic insulating material may be coated. Unfortunately, during the process of cleaning the first substrate <NUM>, the light-emitting elements <NUM> aligned on the first substrate <NUM> may be detached. To prevent detachment, it may be contemplated to form an inorganic insulating material on the light-emitting elements <NUM> to fix the light-emitting elements <NUM>, and to form an organic insulating material. However, such an approach requires etching the organic insulating material and the inorganic insulating material separately. As a result, processes become complicated and productivity may decrease.

According to an embodiment of the disclosure, an ink including light-emitting elements and polymer resins may be prepared, and may be printed on the first substrate <NUM>, so that a first organic insulating layer <NUM> and a second organic insulating layer <NUM> are formed under and on the light-emitting elements <NUM>, respectively. In this manner, the light-emitting elements <NUM> can be fixed. The ink and the method of fabricating a display device will be described later. Structures of the first organic insulating layer <NUM> and the second organic insulating layer <NUM> will be described with reference to the drawings.

<FIG> is a rear view schematically showing light-emitting elements and a first organic insulating layer of a display device according to an embodiment. <FIG> is a plan view schematically showing light-emitting elements and a second organic insulating layer of the display device according to an embodiment. <FIG> is a cross-sectional view schematically showing an example, taken along line Q4 - Q4' of <FIG>. <FIG> is a cross-sectional view schematically showing an example, taken along line Q5 - Q5' of <FIG>. <FIG> is a cross-sectional view schematically showing another example, taken along line Q4 - Q4' of <FIG>. <FIG> is a cross-sectional view schematically showing another example, taken along line Q5 - Q5' of <FIG>.

Referring to <FIG>, the display device <NUM> according to an embodiment includes a first organic insulating layer <NUM> disposed between a first passivation layer PAS1 and the light-emitting elements <NUM>, and a second organic insulating layer <NUM> disposed on the light-emitting elements <NUM>.

The first organic insulating layer <NUM> is disposed between the light-emitting elements <NUM> and the first passivation layer PAS1. The first organic insulating layer <NUM> may include protrusions extended in the first direction DR1, and the first organic insulating layer <NUM> may be extended continuously in the second direction DR2. The first organic insulating layer <NUM> may be aligned in parallel with the first electrode <NUM> or the second electrode <NUM>. The first organic insulating layer <NUM> may have protrusions in the first direction DR1. The extending direction of the light-emitting elements <NUM> may be substantially identical to the direction of the protrusions of the first organic insulating layer <NUM>. It is, however, to be understood that the disclosure is not limited thereto. The arrangement of the first organic insulating layer <NUM> may vary depending on the arrangement of the light-emitting elements <NUM>.

The first organic insulating layer <NUM> may be disposed to overlap the light-emitting elements <NUM> in the emission area EMA of each sub-pixel PXn. The length of the first organic insulating layer <NUM> extended in the first direction DR1 may be substantially identical to the length of the light-emitting elements <NUM>. An end of the first organic insulating layer <NUM> may be disposed on the first electrode <NUM>, and another end of the first organic insulating layer <NUM> may be disposed on the second electrode <NUM>.

The first organic insulating layer <NUM> may be in contact (e.g., direct contact) with the first passivation layer PAS1 and the light-emitting elements <NUM>. For example, the lower surface of the first organic insulating layer <NUM> may be in contact with the upper surface of the first passivation layer PAS1. The upper surface of the first organic insulating layer <NUM> may be in contact with the lower surface of each of the light-emitting elements <NUM>, and, for example, may be in contact with the insulating film <NUM> (see <FIG>) of each of the light-emitting elements <NUM>. The first organic insulating layer <NUM> may be disposed to overlap the light-emitting elements <NUM> along the second direction DR2. The first organic insulating layer <NUM> may be in contact (e.g., direct contact) with the first passivation layer PAS1 and the light-emitting elements <NUM> and may adhere and fix the light-emitting elements <NUM> on the first passivation layer PAS1. In this manner, it may be possible to prevent the light-emitting elements <NUM> from being detached during the cleaning process performed after the process of aligning the light-emitting elements <NUM>.

As shown in <FIG>, the size of the first organic insulating layer <NUM> may be larger than the size of the light-emitting elements <NUM>. Specifically, the size of the first organic insulating layer <NUM> may be larger than the size of the light-emitting elements <NUM> when viewed from the top. The light-emitting elements <NUM> may completely overlap the first organic insulating layer <NUM>. In such a case, one side of the first organic insulating layer <NUM> in the first direction DR1 may be aligned with one side of each of the adjacent light-emitting elements <NUM>, and the opposite side of the first organic insulating layer <NUM> in the first direction DR1 may be aligned with the opposite side of each of the adjacent light-emitting elements <NUM>.

The first organic insulating layer <NUM> may be made of a polymer resin. The polymer resin may include, for example, at least one selected from the group of acrylic-based, epoxy-based, phenol-based, polyamide, polyimide, unsaturated polyester, polyphenylene, polyphenylene sulfide, benzocyclobutene, cardo, siloxane, silsesquioxane, polymethyl methacrylate, and polycarbonate.

On the other hand, the second organic insulating layer <NUM> is disposed on the light-emitting elements <NUM> and is disposed between the light-emitting elements <NUM> and the second passivation layer PAS2. The second organic insulating layer <NUM> may be partially disposed on and in contact (e.g., direct contact) with the light-emitting elements <NUM>. For example, the second organic insulating layer <NUM> may have a width smaller than the length of the light-emitting elements <NUM> and may be disposed on the light-emitting elements <NUM> while surrounding the light-emitting elements <NUM> so that both ends thereof may be exposed.

The second organic insulating layer <NUM> may have a shape extended in the second direction DR2. The direction in which the electrodes <NUM> and <NUM> may be extended may be substantially identical to the direction in which the second organic insulating layer <NUM> may be extended. The second organic insulating layer <NUM> may be extended in the second direction DR2 on the first passivation layer PAS1 when viewed from the top, thereby forming a linear or island-like pattern in each of the sub-pixels PXn.

The second organic insulating layer <NUM> may be disposed to overlap the light-emitting elements <NUM> in the emission area EMA of each sub-pixel PXn. The second organic insulating layer <NUM> may continuously cover the light-emitting elements <NUM> in the second direction DR2. The second organic insulating layer <NUM> can protect the light-emitting elements <NUM> and fix the light-emitting elements <NUM> during the process of fabricating the display device <NUM>.

The second organic insulating layer <NUM> may overlap and may be in contact with the second passivation layer PAS2. For example, the upper surface of the second organic insulating layer <NUM> may be in contact with the lower surface of the second passivation layer PAS2. The size of the second organic insulating layer <NUM> may be equal to the size of the second passivation layer PAS2. Specifically, the size of the second organic insulating layer <NUM> may be equal to the size of the second passivation layer PAS2 when viewed from the top. In such a case, the second organic insulating layer <NUM> may completely overlap the second passivation layer PAS2. For example, a side of the second organic insulating layer <NUM> may be aligned with a side of the adjacent second passivation layer PAS2, and an opposite side of the second organic insulating layer <NUM> may be aligned with an opposite side of the adjacent second passivation layer PAS2.

The width of the first organic insulating layer <NUM> described above may be larger than the width of the second organic insulating layer <NUM>. Specifically, the width W1 of the first organic insulating layer <NUM> in the direction in which the light-emitting elements <NUM> may be extended, e.g., in the first direction DR1 may be larger than the width W2 of the second organic insulating layer <NUM>. The second organic insulating layer <NUM> may be made of a polymer resin and may be made of the same material as the first organic insulating layer <NUM> described above. The first organic insulating layer <NUM> and the second organic insulating layer <NUM> may be formed of the polymer resins of the ink including light-emitting elements simultaneously, and thus may be made of the same material.

Referring to <FIG> and <FIG>, each of the light-emitting elements <NUM> may be spaced apart from the first passivation layer PAS1 with the first organic insulating layer <NUM> therebetween. For example, the light-emitting elements <NUM> may be spaced apart from the first passivation layer PAS1. While the ink is printed, the polymer resins surrounding the light-emitting elements <NUM> may be dripped, and the polymer resins may be coated under the light-emitting elements <NUM>, so that the first organic insulating layer <NUM> may be formed. Therefore, the light-emitting elements <NUM> may be spaced apart from the first passivation layer PAS <NUM>.

The first organic insulating layer <NUM> may surround each of the light-emitting elements <NUM> along the lower curved surface and may be disposed on the first passivation layer PAS1. Accordingly, the first organic insulating layer <NUM> can adhere and fix the light-emitting elements <NUM> to the first passivation layer PAS1. The second organic insulating layer <NUM> may be disposed on the upper central portion of each of the light-emitting elements <NUM>, but may not be disposed on one end of each of the light-emitting elements <NUM>. This is to allow the contact electrode to be easily in contact with the end of each of the light-emitting elements <NUM> during a subsequent process to be described later.

Referring to <FIG> and <FIG>, according to another embodiment, at least a portion of each of the light-emitting elements <NUM> may be in contact (e.g., direct contact) with the first passivation layer PAS1. As described above, while the ink is printed, the polymer resins surrounding the light-emitting elements <NUM> may be dripped, and the polymer resins may spread out in a horizontal direction by the weight of the light-emitting elements <NUM> and may be in contact with the first passivation layer PAS1. Each of the light-emitting elements <NUM> may have a circular cross section. A part thereof may be in contact with the first passivation layer PAS1 while another part thereof may be spaced apart from the first passivation layer PAS <NUM> to be in contact with the first organic insulating layer <NUM>.

Referring back to <FIG>, the first contact electrode CNE1 is in contact with the first end of each of the light-emitting elements <NUM>, and the second contact electrode CNE2 is in contact with the second end of each of the light-emitting elements <NUM>. Specifically, the first contact electrode CNE1 is disposed on the first passivation layer PAS1 and is in contact with an end of the first organic insulating layer <NUM>, the first end of each of the light-emitting elements <NUM>, an end of the second organic insulating layer <NUM> and an end of the second passivation layer PAS2. The second contact electrode CNE2 is disposed on the first passivation layer PAS1 and is in contact with another end of the first organic insulating layer <NUM>, the second end of each of the light-emitting elements <NUM>, another end of the second organic insulating layer <NUM> and another end of the second passivation layer PAS2.

The first contact electrode CNE1 and the second contact electrode CNE2 are in contact with the respective ends of the second passivation layer PAS2, but are not in contact with the upper surface of the second passivation layer PAS2. For example, the first contact electrode CNE1 and the second contact electrode CNE2 are not disposed on the upper surface of the second passivation layer PAS2 and do not overlap the second passivation layer PAS2. During a subsequent process described below, the contact electrode material layer formed on the second passivation layer PAS2 is etched out, and thus the first contact electrode CNE1 and the second contact electrode CNE2 are not in contact with the upper surface of the second passivation layer PAS2.

<FIG> is a view schematically showing a light-emitting element according to an embodiment of the disclosure.

The light-emitting element <NUM> may be a light-emitting diode. Specifically, the light-emitting element <NUM> may have a size in micrometers or nanometers and may be an inorganic light-emitting diode made of an inorganic material. Inorganic light-emitting diodes may be aligned between two electrodes facing each other as polarities may be created by forming an electric field in a particular direction between the two electrodes. The light-emitting elements <NUM> may be aligned between two electrodes by an electric field formed over the two electrodes.

The light-emitting element <NUM> according to an embodiment may have a shape extended in one direction. The light-emitting element <NUM> may have a shape of a cylinder, a rod, a wire, a tube, etc. It is to be understood that the shape of the light-emitting element <NUM> is not limited thereto. The light-emitting element <NUM> may have a variety of shapes including a polygonal column shape such as a cube, a cuboid and a hexagonal column, or a shape that may be extended in a direction with partially inclined outer surfaces. The semiconductors included in the light-emitting element <NUM> to be described later may have a structure sequentially arranged or stacked on each other along the one direction.

The light-emitting element <NUM> may include a semiconductor layer doped with impurities of a conductive type (e.g., p-type or n-type). The semiconductor layers may emit light of a certain wavelength band by transmitting an electric signal applied from an external power source.

As shown in <FIG>, the light-emitting element <NUM> may include a first semiconductor layer <NUM>, a second semiconductor layer <NUM>, an emissive layer <NUM>, an electrode layer <NUM> and an insulating film <NUM>.

The first semiconductor layer <NUM> may be an n-type semiconductor. In the case that the light-emitting element <NUM> emits light of a blue wavelength band, the first semiconductor layer <NUM> may include a semiconductor material having the following chemical formula: AlxGayIn<NUM>-x-yN (<NUM>≤x≤<NUM>, <NUM>≤y≤<NUM>, <NUM>≤x+y≤<NUM>). For example, it may be at least one of n-type doped AlGaInN, GaN, AlGaN, InGaN, AlN and InN. The first semiconductor layer <NUM> may be doped with an n-type dopant, and the n-type dopant may be Si, Ge, Sn, etc. For example, the first semiconductor layer <NUM> may be n-GaN doped with n-type Si. The length of the first semiconductor layer <NUM> may range, but is not limited to, from about <NUM> to about <NUM>.

The second semiconductor layer <NUM> may be disposed on the emissive layer <NUM> to be described later. The second semiconductor layer <NUM> may be a p-type semiconductor. In the case that the light-emitting element <NUM> emits light of a blue or green wavelength band, the second semiconductor layer <NUM> may include a semiconductor material having the following chemical formula: AlxGayIn<NUM>-x-yN (<NUM>≤x≤<NUM>, <NUM>≤y≤<NUM>, <NUM>≤x+y≤<NUM>). For example, it may be at least one of p-type doped AlGaInN, GaN, AlGaN, InGaN, AlN and InN. The second semiconductor layer <NUM> may be doped with a p-type dopant, and the p-type dopant may be Mg, Zn, Ca, Se, Ba, etc. For example, the second semiconductor layer <NUM> may be p-GaN doped with p-type Mg. The length of the second semiconductor layer <NUM> may range, but is not limited to, from about <NUM> to about <NUM>.

Although each of the first semiconductor layer <NUM> and the second semiconductor layer <NUM> may be embodied as a signal layer in the drawings, the disclosure is not limited thereto. Depending on the material of the emissive layer <NUM>, the first semiconductor layer <NUM> and the second semiconductor layer <NUM> may further include a larger number of layers, e.g., a clad layer or a tensile strain barrier reducing (TSBR) layer.

The emissive layer <NUM> may be disposed between the first semiconductor layer <NUM> and the second semiconductor layer <NUM>. The emissive layer <NUM> may include a material having a single or multiple quantum well structure. In the case that the emissive layer <NUM> includes a material having the multiple quantum well structure, the structure may include quantum layers and well layers alternately stacked on one another. The emissive layer <NUM> may emit light as electron-hole pairs may be combined therein in response to an electrical signal applied through the first semiconductor layer <NUM> and the second semiconductor layer <NUM>. In the case that the emissive layer <NUM> emits light of the blue wavelength band, it may include a material such as AlGaN and AlGaInN. In particular, in the case that the emissive layer <NUM> has a multi-quantum well structure in which quantum layers and well layers may be alternately stacked on one another, the quantum layers may include AlGaN or AlGaInN, and the well layers may include a material such as GaN and AlGaN. For example, the emissive layer <NUM> may include AlGaInN as the quantum layer and AlInN as the well layer, and, as described above, the emissive layer <NUM> may emit blue light having a center wavelength band of about <NUM> to about <NUM>.

It is, however, to be understood that the disclosure is not limited thereto. The emissive layer <NUM> may have a structure in which a semiconductor material having a large band gap energy and a semiconductor material having a small band gap energy may be alternately stacked on one another, and may include other Group III to Group V semiconductor materials depending on the wavelength range of the emitted light. Accordingly, the light emitted from the emissive layer <NUM> is not limited to the light of the blue wavelength band. The emissive layer <NUM> may emit light of red or green wavelength bands in some embodiments. The length of the emissive layer <NUM> may be, but is not limited to, in the range of about <NUM> to about <NUM>.

The light emitted from the emissive layer <NUM> may exit not only through the outer surfaces of the light-emitting element <NUM> in the longitudinal direction but also through the side surfaces. The direction in which the light emitted from the emissive layer <NUM> propagates is not limited to one direction.

The electrode layer <NUM> may be an ohmic contact electrode. It is, however, to be understood that the disclosure is not limited thereto. The electrode layer <NUM> may be a Schottky contact electrode. The light-emitting element <NUM> may include at least one electrode layer <NUM>. Although the light-emitting element <NUM> includes one electrode layer <NUM> in the example shown in <FIG>, the disclosure is not limited thereto. In some implementations, the light-emitting element <NUM> may include a larger number of electrode layers <NUM> or the electrode layer may be omitted. The following description of the light-emitting element <NUM> may be equally applied even if the number of electrode layers <NUM> may be different or it further includes other structures.

The electrode layer <NUM> can reduce the resistance between the light-emitting element <NUM> and the electrodes or the contact electrodes in the case that the light-emitting element <NUM> may be electrically connected to the electrodes or the contact electrodes in the display device <NUM> according to an embodiment of the disclosure. The electrode layer <NUM> may include a metal having conductivity. For example, the electrode layer <NUM> may include at least one of aluminium (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), indium tin oxide (ITO), indium zinc oxide (IZO) and indium tin-zinc oxide (ITZO). The electrode layer <NUM> may include a semiconductor material doped with n-type or p-type impurities. The electrode layer <NUM> may include the same material or may include different materials. It is, however, to be understood that the disclosure is not limited thereto.

The insulating film <NUM> may be disposed to surround outer surfaces of the semiconductor layers and electrode layers described above. For example, the insulating film <NUM> may be disposed to surround at least the outer surface of the emissive layer <NUM>, and may be extended in a direction in which the light-emitting element <NUM> may be extended. The insulating film <NUM> may serve to protect the above-described elements. The insulating film <NUM> may be formed to surround the side surfaces of the elements, and both ends of the light-emitting element <NUM> in the longitudinal direction may be exposed.

Although the insulating film <NUM> may be extended in the longitudinal direction of the light-emitting element <NUM> to cover from the first semiconductor layer <NUM> to the side surface of the electrode layer <NUM> in the example shown in the drawing, the disclosure is not limited thereto. The insulating film <NUM> may cover only the outer surface of a portion of the semiconductor layer, including the light-emitting layer <NUM>, or may cover only a portion of the outer surface of the electrode layer <NUM> to partially expose the outer surface of the electrode layer <NUM>. A portion of the upper surface of the insulating film <NUM> may be rounded which may be adjacent to at least one end of the light-emitting element <NUM> in cross section.

The thickness of the insulating film <NUM> may be, but is not limited to, in the range of about <NUM> to about <NUM>. In an embodiment, the thickness of the insulating film <NUM> may be approximately <NUM>.

The insulating film <NUM> may include materials having an insulating property such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminium nitride (AlN) and aluminium oxide (Al<NUM>O<NUM>). Accordingly, it may be possible to prevent an electrical short-circuit that may occur in the case that the emissive layer <NUM> comes in contact with an electrode through which an electric signal may be transmitted to the light-emitting element <NUM>. Since the light-emitting element <NUM> may include the insulating film <NUM> to protect the outer surface of the emissive layer <NUM>, it may be possible to prevent a decrease in luminous efficiency.

The outer surface of the insulating film <NUM> may be subjected to surface treatment. The light-emitting elements <NUM> may be dispersed in an ink, and droplets of the ink may be ejected onto an electrode. In doing so, a surface treatment may be applied to the insulating film <NUM> so that it becomes hydrophobic or hydrophilic in order to keep the light-emitting elements <NUM> dispersed in the ink from being aggregated with one another. For example, the outer surface of the insulating film <NUM> may be subjected to surface treatment with a material such as stearic acid and <NUM>,<NUM>-naphthalene dicarboxylic acid.

The length h of the light-emitting element <NUM> may range from about <NUM> to about <NUM> or from about <NUM> to about <NUM>, and in an embodiment, approximately <NUM> to approximately <NUM>. The diameter of the light-emitting elements <NUM> may range from about <NUM> to about <NUM>, and the aspect ratio of the light-emitting elements <NUM> may range from about <NUM> to about <NUM>. It is, however, to be understood that the disclosure is not limited thereto. The light-emitting elements <NUM> included in the display device <NUM> may have different diameters depending on compositional difference of the emissive layer <NUM>. In an embodiment, the diameter of the light-emitting elements <NUM> may be approximately <NUM>.

It is to be noted that the shape and material of the light-emitting element <NUM> are not limited to those described with reference to <FIG>. In some embodiments, the light-emitting elements <NUM> may include a greater number of layers or may have different shapes.

<FIG> is a view schematically showing a light-emitting element according to another embodiment of the disclosure.

Referring to <FIG>, a light-emitting element <NUM>' according to another embodiment may further include a third semiconductor layer <NUM>' disposed between a first semiconductor layer <NUM>' and an emissive layer <NUM>', and a fourth semiconductor layer <NUM>' and a fifth semiconductor layer <NUM>' disposed between the emissive layer <NUM>' and the second semiconductor layer <NUM>'. The light-emitting element <NUM>' of <FIG> may be different from the light-emitting element of <FIG> in that semiconductor layers <NUM>', <NUM>' and <NUM>' and electrode layers 37a' and 37b' may be further disposed, and that an emissive layer <NUM>' may include different elements. In the following description, descriptions will focus on the differences, and redundant description will be omitted.

The emissive layer <NUM> of the light-emitting element <NUM> of <FIG> may include nitrogen (N) and thus may emit blue or green light. On the other hand, in the light-emitting element <NUM>' of <FIG>, the emissive layer <NUM>' and other semiconductor layers each may be a semiconductor including at least phosphorus (P). The light-emitting element <NUM>' according to an embodiment of the disclosure may emit red light having a center wavelength band of about <NUM> to about <NUM>. It is, however, to be understood that the center wavelength band of red light is not limited to the above numerical values and may encompass all wavelength ranges that can be recognized as red in the art.

Specifically, the first semiconductor layer <NUM>' may include, as an n-type semiconductor layer, a semiconductor material having the following chemical formula: InxAlyGa<NUM>-x-yP (<NUM>≤x≤<NUM>, <NUM>≤y≤<NUM>, <NUM>≤x+y≤<NUM>). The first semiconductor layer <NUM>' may be one or more of n-type InAlGaP, GaP, AlGaP, InGaP, AlP and InP. For example, the first semiconductor layer <NUM>' may be n-AlGaInP doped with n-type Si.

Specifically, the second semiconductor layer <NUM>' may include, as a p-type semiconductor layer, a semiconductor material having the following chemical formula: InxAlyGa<NUM>-x-yP (<NUM>≤x≤<NUM>, <NUM>≤y≤<NUM>, <NUM>≤x+y≤<NUM>). The second semiconductor layer <NUM>' may be one or more of p-type InAlGaP, GaP, AlGaP, InGaP, AlP and InP. For example, the second semiconductor layer <NUM>' may be p-GaP doped with p-type Mg.

The emissive layer <NUM>' may be disposed between the first semiconductor layer <NUM>' and the second semiconductor layer <NUM>'. The emissive layer <NUM>' may include a material having a single or multiple quantum well structure and may emit light of a certain wavelength band. In the case that the emissive layer <NUM>' has a multi-quantum well structure in which quantum layers and well layers are alternately stacked on one another, the quantum layers may include AlGaP or AlInGaP, and the well layers may include GaP or AlInP. For example, the emissive layer <NUM>' may include AlGaInP as the quantum layers and AlInP as the well layers and may emit red light having a central wavelength band of about <NUM> to about <NUM>.

The light-emitting element <NUM>' of <FIG> may include a clad layer disposed adjacent to the emissive layer <NUM>'. As shown in <FIG>, the third semiconductor layer <NUM>' and the fourth semiconductor layer <NUM>' disposed under and on the emissive layer <NUM>' between the first semiconductor layer <NUM>' and the second semiconductor layer <NUM>' may be clad layers.

The third semiconductor layer <NUM>' may be disposed between the first semiconductor layer <NUM>' and the emissive layer <NUM>'. The third semiconductor layer <NUM>' may be an n-type semiconductor like the first semiconductor layer <NUM>', and may include a semiconductor material having the following chemical formula: InxAlyGa<NUM>-x-yP (<NUM>≤x≤<NUM>, <NUM>≤y≤<NUM>, <NUM>≤x+y≤<NUM>). For example, the first semiconductor layer <NUM>' may be n-AlGaInP, and the third semiconductor layer <NUM>' may be n-AlInP. It is, however, to be understood that the disclosure is not limited thereto.

The fourth semiconductor layer <NUM>' may be disposed between the emissive layer <NUM>' and the second semiconductor layer <NUM>'. The fourth semiconductor layer <NUM>' may be an p-type semiconductor like the second semiconductor layer <NUM>', and may include a semiconductor material having the following chemical formula: InxAlyGa<NUM>-x-yP (<NUM>≤x≤<NUM>, <NUM>≤y≤<NUM>, <NUM>≤x+y≤<NUM>). For example, the second semiconductor layer <NUM>' may be p-GaP, and the fourth semiconductor layer <NUM>' may be p-AlInP.

The fifth semiconductor layer <NUM>' may be disposed between the fourth semiconductor layer <NUM>' and the second semiconductor layer <NUM>'. The fifth semiconductor layer <NUM>' may be a p-type doped semiconductor, like the second semiconductor layer <NUM>' and the fourth semiconductor layer <NUM>'. In some embodiments, the fifth semiconductor layer <NUM>' may reduce a difference in lattice constant between the fourth semiconductor layer <NUM>' and the second semiconductor layer <NUM>'. The fifth semiconductor layer <NUM>' may be a tensile strain barrier reducing (TSBR) layer. For example, the fifth semiconductor layer <NUM>' may include, but is not limited to, p-GaInP, p-AlInP, p-AlGaInP, etc. The length of the third semiconductor layer <NUM>', the fourth semiconductor layer <NUM>' and the fifth semiconductor layer <NUM>' may be, but are not limited to, a range of about <NUM>µmm to about <NUM>.

The first electrode layer 37a' and the second electrode layer 37b' may be disposed on the first semiconductor layer <NUM>' and the second semiconductor layer <NUM>', respectively. The first electrode layer 37a' may be disposed on the lower surface of the first semiconductor layer <NUM>', and the second electrode layer 37b' may be disposed on the upper surface of the second semiconductor layer <NUM>'. It is, however, to be understood that the disclosure is not limited thereto. At least one of the first electrode layer 37a' and the second electrode layer 37b' may be eliminated. For example, in the light-emitting element <NUM>', the first electrode layer 37a' may not be disposed on the lower surface of the first semiconductor layer <NUM>', and the second electrode layer 37b' may be disposed on the upper surface of the second semiconductor layer <NUM>'.

The above-described light-emitting elements <NUM> may be ejected onto the electrodes <NUM> and <NUM> via an inkjet printing process. The light-emitting elements <NUM> dispersed in a solvent may be ejected onto the electrodes <NUM> and <NUM>, and an alignment signal may be applied to the electrodes <NUM> and <NUM>, so that the light-emitting elements can be disposed between the electrodes <NUM> and <NUM>. In the case that an alignment signal is applied to the electrodes <NUM> and <NUM>, an electric field may be formed over them, and the light-emitting elements <NUM> may receive a dielectrophoretic force by the electric field. In the case that the light-emitting elements <NUM> receive the dielectrophoretic force, they may be disposed between the first electrode <NUM> and the second electrode <NUM> with their orientations and locations changed.

According to an embodiment of the disclosure, the ink including the light-emitting elements <NUM> may include the polymer resins, and the first organic insulating layer <NUM> and the second organic insulating layer <NUM> can be formed under and on the aligned light-emitting elements <NUM>, respectively. In this manner, it may be possible to prevent the light-emitting elements <NUM> from being detached during the cleaning process performed after the light-emitting elements <NUM> have been aligned.

Hereinafter, the ink including the light-emitting elements <NUM> will be described.

<FIG> is a view schematically showing an ink including light-emitting elements according to an embodiment of the disclosure.

Referring to <FIG>, an ink <NUM> according to an embodiment of the disclosure may include a solvent <NUM>, and light-emitting elements <NUM> and polymer resins <NUM> dispersed in the solvent <NUM>. The light-emitting elements <NUM> may be either the light-emitting element <NUM> or the light-emitting element <NUM>' described above with reference to <FIG> and <FIG>. The light-emitting element <NUM> of <FIG> is shown in <FIG>. The light-emitting elements <NUM> have already been described above, and thus the solvent <NUM> and the polymer resins <NUM> will be described in detail below.

The solvent <NUM> may store the light-emitting elements <NUM> each including semiconductor layers as they may be dispersed therein, and may be an organic solvent that does not react with the light-emitting elements <NUM>. The solvent <NUM> may have such a viscosity that it can be discharged in a liquid state through a nozzle of an inkjet printing apparatus. The molecules of the solvent <NUM> may surround the surfaces of the light-emitting elements <NUM> and disperse the light-emitting elements <NUM>. The ink <NUM> including the light-emitting elements <NUM> may be prepared in a solution or colloid.

According to an embodiment of the disclosure, the solvent <NUM> may be, but is not limited to, acetone, water, alcohol, toluene, propylene glycol (PG) or propylene glycol methyl acetate (PGMA), triethylene glycol monobutyl ether, diethylene glycol monophenyl ether, amide solvent, dicarbonyl solvent, diethylene glycol dibenzoate, tricarbonyl solvent, triethyl citrate, phthalate solvent, benzyl butyl phthalate, bis(<NUM>-ethlyhexyl)phthalate, bis(<NUM>-ethylhexyl)isophthalate, ethyl phthalyl ethyl glycolate, or a combination thereof.

The polymer resins <NUM> may be dispersed in the solvent <NUM> together with the light-emitting elements <NUM>. A content of the polymer resins <NUM> may be included in the ink <NUM>. After the light-emitting elements <NUM> have been aligned, the polymer resins <NUM> may be formed as the first organic insulating layer <NUM> and the second organic insulating layer <NUM>.

According to an embodiment of the disclosure, the polymer resins <NUM> included in the ink <NUM> may include at least one selected from the group of acrylic-based, epoxy-based, phenol-based, polyamide, polyimide, unsaturated polyester, polyphenylene, polyphenylene sulfide, benzocyclobutene, cardo, siloxane, silsesquioxane, polymethyl methacrylate, and polycarbonate. By using the ink <NUM> including the polymer resins <NUM>, the first organic insulating layer <NUM> and the second organic insulating layer <NUM> can be formed to adhere and fix the light-emitting elements <NUM> after they have been aligned, thereby preventing the light-emitting elements <NUM> from being detached.

The ink <NUM> may include a constant content of light-emitting elements <NUM> per weight, and the polymer resins <NUM> may be included at a constant content relative to the weight of the ink <NUM>.

According to an embodiment of the disclosure, the ink <NUM> may include the polymer resins <NUM> from about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the ink <NUM>. If the polymer resins <NUM> are presented in an amount of about <NUM> part by weight based on <NUM> parts by weight of the ink <NUM> or more, the first and second organic insulating layers <NUM> and <NUM> formed on and under the light-emitting elements <NUM> can have an effective thickness. If the polymer resins <NUM> are presented in an amount of <NUM> parts by weight or less, it may be possible to prevent that the viscosity of the ink <NUM> may be too high thereby making ejection of the ink difficult.

The content of the light-emitting elements <NUM> included in the ink <NUM> may vary depending on the number of light-emitting elements <NUM> per droplet of the ink <NUM> discharged through a nozzle during a printing process. According to an embodiment of the disclosure, the light-emitting elements <NUM> may be included in the solvent from about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the ink <NUM>. It is, however, to be noted that this is merely illustrative, and the content of the light-emitting elements <NUM> may vary depending on the number of light-emitting elements <NUM> per droplet of the ink <NUM>.

The ink <NUM> may further include a dispersant (not shown) that improves the degree of dispersion of the light-emitting elements <NUM>. The type of the dispersant is not particularly limited herein. The content of the dispersant may be determined appropriately to further disperse the light-emitting elements <NUM>. For example, the dispersant may be included from about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the light-emitting elements <NUM>. It is, however, to be understood that the disclosure is not limited thereto.

In fabricating a display device including the light-emitting elements <NUM> by using the ink <NUM> according to an embodiment of the disclosure, a uniform number of light-emitting elements <NUM> per unit area can be disposed, and the solvent <NUM> remained as a foreign substance can be completely removed.

During the process of fabricating the display device <NUM>, a process of disposing the light-emitting elements <NUM> on the electrodes <NUM> and <NUM> may be carried out, which may be carried out via the printing process using the ink <NUM>.

Hereinafter, processing steps of fabricating the display device <NUM> according to an embodiment of the disclosure will be described with reference to other drawings.

<FIG> is a flowchart of a method of fabricating a display device according to an embodiment of the disclosure.

Referring to <FIG>, a method of fabricating a display device <NUM> according to an embodiment of the disclosure may include preparing an ink <NUM> in which light-emitting elements <NUM> and polymer resins <NUM> may be dispersed in a solvent <NUM>, and a target substrate SUB having a first passivation layer PAS1 formed on a first electrode <NUM> and a second electrode <NUM> (step S100), ejecting the ink <NUM> onto the target substrate SUB (step S200), generating an electric field over the target substrate to align the light-emitting elements <NUM> on the first electrode <NUM> and the second electrode <NUM> (step S300), removing the solvent <NUM> and forming a first organic layer <NUM> (described below) surrounding the light-emitting elements <NUM> (step S400), and forming a second organic layer <NUM> (described below) on the first organic layer <NUM>, forming a mask pattern MP on the second organic layer <NUM>, and etching out the first organic layer <NUM> and the second organic layer <NUM> simultaneously (step S500).

Hereinafter, a method of fabricating the display device <NUM> will be described in detail with reference to other drawings in conjunction with <FIG>.

<FIG> are cross-sectional views schematically showing some of the processing steps of fabricating a display device according to an embodiment of the disclosure.

Initially, referring to <FIG>, an ink <NUM> including light-emitting elements <NUM>, a solvent <NUM> and polymer resins <NUM>, and a target substrate SUB on which a first electrode <NUM>, a second electrode <NUM>, a first passivation layer PAS1 and first banks BNL1 may be disposed may be prepared. Openings OP may be formed in the first passivation layer PAS1, via which electrode layers <NUM> and <NUM> may be exposed, respectively. Although a pair of electrodes may be disposed on the target substrate SUB in the drawing, a larger number of electrode pairs may be disposed on the target substrate SUB. The target substrate SUB may include circuit elements disposed thereon in addition to the first substrate <NUM> of the display device <NUM> described above. In the following description, the circuit elements will be omitted for convenience of illustration.

The ink <NUM> may include the solvent <NUM>, and the light-emitting elements <NUM> and the polymer resins <NUM> dispersed in the solvent <NUM>. The polymer resins <NUM> may be uniformly dispersed in the solvent <NUM>.

The preparing of the ink <NUM> may include a process of mixing the light-emitting elements <NUM>, the solvent <NUM>, the polymer resins <NUM>, and a dispersant. As another example, the preparing the ink <NUM> may include a first dispersion process of mixing the light-emitting elements <NUM>, the solvent <NUM> and the dispersant, and a second dispersion process of adding the polymer resins <NUM> to the solution produced by the first dispersion process.

The dispersion process may be performed by mixing the light-emitting elements <NUM>, the polymer resins <NUM> and the dispersant in the solvent <NUM>, and mixing them for about <NUM> minutes or more. As described above, each of the light-emitting elements <NUM> may have a diameter of about <NUM> or less, or about <NUM> or less, and a length of about <NUM> to about <NUM>, or approximately <NUM>. The light-emitting elements <NUM> may be included from about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the ink <NUM>. The polymer resins <NUM> may be included from about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the ink <NUM>. The dispersant may be included from about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the light-emitting elements <NUM>. The mixing process may be performed by a sonication process, a stirring process, a milling process, etc., or a combination thereof.

The ink <NUM> produced by the dispersion process may be stored at room temperature (about <NUM>). The polymer resins <NUM> of the ink <NUM> may be uniformly dispersed with the solvent <NUM> and the light-emitting elements <NUM>. The light-emitting elements <NUM> may hardly precipitate and may remain dispersed.

Subsequently, referring to <FIG>, droplets of the ink <NUM> may be ejected onto the first passivation layer PAS1 covering the first electrode <NUM> and the second electrode <NUM> on the target substrate SUB. According to an embodiment of the disclosure, droplets of the ink <NUM> may be ejected onto the first passivation layer PAS1 via a printing process using an inkjet printing apparatus. The droplets of the ink <NUM> may be ejected through a nozzle of an inkjet head included in the inkjet printing apparatus. The ink <NUM> may flow along an internal path formed in the inkjet head and may be discharged onto the target substrate SUB through the nozzle. The droplets of the ink <NUM> discharged from the nozzle may seat on the first passivation layer PAS1 on which the electrodes <NUM> and <NUM> disposed on the target substrate SUB may be formed. The light-emitting elements <NUM> may have a shape extending in a direction, and may be dispersed in the ink <NUM> with the direction randomly oriented.

In the case that the droplets of the ink <NUM> are ejected onto the first passivation layer PAS1, the ink <NUM> may evenly spread in the second bank BNL2 without overflowing the second bank BNL2. Accordingly, the light-emitting elements <NUM> and the polymer resins <NUM> dispersed in the ink <NUM> may be evenly distributed in the second bank BNL2.

Subsequently, a process of generating an electric field over the target substrate SUB to align the light-emitting elements <NUM> on the electrodes <NUM> and <NUM> (step S300) may be performed.

Referring to <FIG>, after the droplets of the ink <NUM> including the light-emitting elements <NUM> may be ejected onto the target substrate SUB, an alignment signal may be applied to the electrodes <NUM> and <NUM> to generate an electric field EL over the target substrate SUB. The light-emitting elements <NUM> dispersed in the solvent <NUM> may receive a dielectrophoretic force by the electric field EL, and may be disposed on the electrodes <NUM> and <NUM> with their orientations and locations changed.

In the case that the electric field EL is generated over the target substrate SUB, the light-emitting elements <NUM> may receive the dielectrophoretic force. In the case that the electric field EL generated over the target substrate SUB is parallel to the upper surface of the target substrate, the light-emitting elements <NUM> may be aligned such that the direction in which they are extended may be parallel to the target substrate, and may be disposed on the first electrode <NUM> and the second electrode <NUM>. The light-emitting elements <NUM> may move toward the electrodes <NUM> and <NUM> from the initially dispersed locations by the dielectrophoretic force. Both ends of each of the light-emitting elements <NUM> may be disposed on the first electrode <NUM> and the second electrode <NUM>, respectively, while their orientations may be changed by the electric field EL. Each of the light-emitting elements <NUM> may include semiconductor layers doped with different conductivity types, and may have a dipole moment within therein. The light-emitting elements <NUM> having the dipole moment may receive the dielectrophoretic force so that the ends may be disposed on the electrodes <NUM> and <NUM>, respectively, in the case that they may be placed under the electric field EL.

After the light-emitting elements <NUM> have been disposed between the electrodes <NUM> and <NUM>, heat may be applied to the target substrate SUB to remove the solvent <NUM> so that the first organic layer <NUM> surrounding the light-emitting elements <NUM> may be formed (step S400).

Referring to <FIG> and <FIG>, the process of removing the solvent <NUM> may be carried out in a chamber VCD of which internal pressure may be adjustable. The chamber VCD may adjust the internal pressure therein, and may remove the solvent <NUM> by irradiating heat on the target substrate SUB with the pressure adjusted.

According to the method of fabricating the display device <NUM>, it may be possible to completely remove the solvent <NUM> by heat treatment in a low-pressure environment. According to an embodiment of the disclosure, the process of removing the solvent <NUM> may be carried out under a pressure of about <NUM>-<NUM> Torr to <NUM> Torr at a temperature of about <NUM> to about <NUM>. In the case that a heat treatment process is carried out under the above pressure ranges, the boiling point of the solvent <NUM> may be also lowered, so that it can be more easily removed. The heat treatment process in the chamber VCD may be carried out for <NUM> minute to <NUM> minutes. It is, however, to be understood that the disclosure is not limited thereto.

In the case that the light-emitting elements <NUM> are seated on the first passivation layer PAS1 before the solvent <NUM> may be removed, the polymer resins <NUM> may be formed to surround the light-emitting elements <NUM>. During the process of removing the solvent <NUM>, in the case that the heat treatment process may be performed, the polymer resins <NUM> may be baked simultaneously, so that the first organic layer <NUM> may be formed. The first organic layer <NUM> may be formed on the first passivation layer PAS1 and may be formed to completely surround the light-emitting elements <NUM>.

Subsequently, a second organic layer <NUM> may be formed on the first organic layer <NUM>, and a mask pattern MP may be formed on the second organic layer <NUM>, so that the first organic layer <NUM> and the second organic layer <NUM> may be etched simultaneously (step S500).

Referring to <FIG> and <FIG>, the second organic layer <NUM> may be formed on the first organic layer <NUM>. The second organic layer <NUM> may be formed of the same material as or a different material from that of the first organic layer <NUM>. The mask pattern MP may be formed on the second organic layer <NUM>. The mask pattern MP may be formed so that it overlaps a portion of the light-emitting element <NUM>. The mask pattern MP may be formed as a hard mask such as ITO.

Subsequently, the first organic layer <NUM> and the second organic layer <NUM> may be simultaneously etched by performing a dry etching process using the mask pattern MP. By this etching process, parts of the second organic layer <NUM> that do not overlap the mask pattern MP may be all etched out. The mask pattern MP and the light-emitting elements <NUM> may work as a mask, so that the first organic layer <NUM> may be etched out leaving its parts under the mask pattern MP and the light-emitting element <NUM>. Subsequently, the mask pattern MP may be removed, and accordingly the first organic insulating layer <NUM> disposed under the light-emitting elements <NUM>, the second organic insulating layer <NUM> disposed on the light-emitting elements <NUM>, and the second passivation layer PAS2 disposed on the second organic insulating layer <NUM> may be formed.

Subsequently, an electrode material layer <NUM> may be stacked on the first passivation layer PAS1 and the second passivation layer PAS2, and may be etched using a photoresist pattern PP.

Referring to <FIG>, the electrode material layer <NUM> may be stacked on the first passivation layer PAS1 and the second passivation layer PAS2. The electrode material layer <NUM> may be in contact with the electrodes <NUM> and <NUM> via the openings OP of the first passivation layer PAS1 and in contact with both ends of the light-emitting element <NUM>. Subsequently, a photoresist PR may be coated on the electrode material layer <NUM>, exposed to light and developed to form the photoresist pattern PP. The photoresist pattern PP may be formed so that it overlaps the first banks BNL1 and both ends of the light-emitting element <NUM> but not with the second passivation layer PAS2.

Subsequently, as shown in <FIG>, by etching the electrode material layer <NUM> using the photoresist pattern PP, a first contact electrode CNE1 and a second contact electrode CNE2 may be formed. The electrode material layer <NUM> may be etched on the second passivation layer PAS2 so that the first contact electrode CNE1 and the second contact electrode CNE2 spaced apart from each other may be formed. By performing the above-described processes, the display device <NUM> including the light-emitting elements <NUM> can be fabricated.

Claim 1:
A display device (<NUM>) comprising:
a substrate (<NUM>);
a first electrode (<NUM>) and a second electrode (<NUM>) that extend in a second direction (DR2) on the substrate (<NUM>) and are spaced apart from each other in a first direction (DR1) on the substrate (<NUM>) perpendicular to the second direction (DR2);
a first passivation layer (PAS1) disposed on the substrate (<NUM>) and overlapping the first electrode (<NUM>) and the second electrode (<NUM>) in a vertical direction which is perpendicular to the substrate (<NUM>);
at least one light-emitting element (<NUM>) disposed on the first passivation layer (PAS1) and having ends disposed on the first electrode (<NUM>) and the second electrode (<NUM>), respectively;
a first organic insulating layer (<NUM>) disposed between the first passivation layer (PAS1) and the at least one light-emitting element (<NUM>);
a second organic insulating layer (<NUM>) disposed on the at least one light-emitting element (<NUM>);
a first contact electrode (CNE1) disposed on the first electrode (<NUM>) and electrically contacting a first end of the at least one light-emitting element (<NUM>);
a second contact electrode (CNE2) disposed on the second electrode (<NUM>) and electrically contacting a second end of the at least one light-emitting element (<NUM>); and
a second passivation layer (PAS2) disposed on the second organic insulating layer (<NUM>),
wherein the first contact electrode (CNE1) is in direct contact with an end of each of the second organic insulating layer (<NUM>) and the second passivation layer (PAS2),
the second contact electrode (CNE2) is in direct contact with another end of each of the second organic insulating layer (<NUM>) and the second passivation layer (PAS2), and
the first contact electrode (CNE1) and the second contact electrode (CNE2) are not in direct contact with an upper surface of the second passivation layer (PAS2).