Display device

Abstract

A display device is provided. The display device comprises a substrate, a first electrode and a second electrode spaced apart from each other on one surface of the substrate, and a light-emitting element extending in a first direction, wherein one end in the first direction is placed on the first electrode and the other end in the first direction is placed on the second electrode, wherein the first diameter of the one end of the light-emitting element is different from the second diameter of the other end of the light-emitting element, and the light-emitting element comprises a first semiconductor layer, a second semiconductor layer spaced apart from the first semiconductor layer, and an active layer placed between the first semiconductor layer and the second semiconductor layer, wherein the active layer is located adjacent to the end side having the larger diameter between the first diameter and the second diameter.

Description

Technology Field

[0001] The present invention relates to a display device. Background Technology

[0002] The importance of display devices is increasing along with the development of multimedia. In response to this, various types of display devices, such as Organic Light Emitting Displays (OLEDs) and Liquid Crystal Displays (LCDs), are being used.

[0003] A device for displaying images of a display device includes a display panel such as an organic light-emitting display panel or a liquid crystal display panel. Among these, as a light-emitting display panel, it may include a light-emitting element; for example, in the case of a light-emitting diode (LED), there are organic light-emitting diodes (OLEDs) that use organic materials as light-emitting materials, and inorganic light-emitting diodes that use inorganic materials as light-emitting materials. The problem to be solved

[0004] The problem that the present invention aims to solve is to provide a display device with improved light emission efficiency.

[0005] The problems of the present invention are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0006] A display device according to one embodiment for solving the above problem comprises a substrate, a first electrode and a second electrode spaced apart from each other on one surface of the substrate, and a light-emitting element extending in a first direction, wherein one end in the first direction is placed on the first electrode and the other end in the first direction is placed on the second electrode, wherein the first diameter of the first end of the light-emitting element is different from the second diameter of the other end of the light-emitting element, and the light-emitting element comprises a first semiconductor layer, a second semiconductor layer spaced apart from the first semiconductor layer, and an active layer placed between the first semiconductor layer and the second semiconductor layer, wherein the active layer is located adjacent to the end side having the larger diameter between the first diameter and the second diameter.

[0007] The second diameter is larger than the first diameter, and at least a portion of the active layer may be disposed on the second electrode.

[0008] At least a portion of the active layer may overlap the second electrode and the substrate in the thickness direction.

[0009] The second electrode above can completely cover the active layer in the thickness direction of the substrate at the bottom of the active layer.

[0010] The second semiconductor layer may be disposed on one end side of the light-emitting element, and the first semiconductor layer may be disposed on the other end side of the light-emitting element.

[0011] The thickness of the first semiconductor layer in the first direction may be smaller than the thickness of the second semiconductor layer in the first direction.

[0012] The light-emitting element can emit red light having a central wavelength band in the range of 600 nm to 750 nm.

[0013] The first semiconductor layer and the second semiconductor layer may each include phosphorus (P).

[0014] The minimum diameter of the first semiconductor layer may be larger than the maximum diameter of the second semiconductor layer.

[0015] The diameter of the active layer can decrease from the first semiconductor layer to the second semiconductor layer.

[0016] The light-emitting element includes a first surface which is one end surface, a second surface which is the other end surface, and a third surface connecting the first surface and the second surface, and the first distance in the first direction between the first surface and the first surface of the active layer facing the first surface may be longer than the second distance in the first direction between the other surface of the active layer facing the second surface and the second surface.

[0017] The cross-sectional shape of the light-emitting element cut along the first direction may be a trapezoidal shape.

[0018] The diameter of the light-emitting element can be reduced along the first direction.

[0019] The first semiconductor layer, the active layer, and the second semiconductor layer may be arranged sequentially along the first direction.

[0020] The device further includes a first insulating layer disposed on the light-emitting element to expose one end and the other end of the light-emitting element, wherein the first insulating layer may not overlap with at least a portion of the active layer in the thickness direction of the substrate.

[0021] The active layer comprises a first region that overlaps the first insulating layer and the substrate in the thickness direction and a second region that does not overlap, and the thickness of the first region in the first direction may be smaller than the thickness of the second region in the first direction.

[0022] The above active layer may not overlap with the first insulating layer in the thickness direction of the substrate.

[0023] The apparatus further comprises a first contact electrode in contact with one end of the light-emitting element and the first electrode; and a second contact electrode in contact with the other end of the light-emitting element and the second electrode, wherein the first contact electrode and the second contact electrode may be electrically insulated from each other.

[0024] One end and the other end of the light-emitting element may be tilted with respect to one surface of the substrate.

[0025] With respect to one surface of the substrate, the inclined directions of one end and the other end of the light-emitting element may be the same.

[0026] Specific details of other embodiments are included in the detailed description and drawings. Effects of the invention

[0027] A display device according to one embodiment may include a light-emitting element that emits light, comprising a first semiconductor layer, a second semiconductor layer, and an active layer, having a trapezoidal cross-sectional shape in which the diameters of the two ends are different from each other. By positioning the active layer of the light-emitting element adjacent to the end with the larger diameter among the two ends, the volume of the active layer increases, thereby increasing the amount of light emitted by the light-emitting element.

[0028] In addition, the active layer can be positioned adjacent to the end side with a larger diameter so that it overlaps with the electrodes positioned at the bottom of the light-emitting element in the display direction. By positioning the active layer to overlap with the electrodes, the proportion of light emitted from the active layer and traveling downwards that travels toward the electrodes is increased, thereby changing the direction of light propagation toward the display direction through reflection by the electrodes and improving the light emission efficiency of the display device.

[0029] In addition, the active layer can be positioned adjacent to the end side with a larger diameter so that the insulating layer, which is placed on the light-emitting element to fix the light-emitting element, and the active layer can be positioned so as not to overlap in the display direction. By positioning the insulating layer and the active layer so as not to overlap, thereby reducing the amount of light transmitted from the active layer due to the difference in refractive index, the ratio of light emitted from the active layer and incident on the insulating layer is reduced, thereby improving the light emission efficiency of the display device. By forming the first contact electrode and the second contact electrode through the same process using a sacrificial pattern, the number of masks is reduced, and the process efficiency of the display device can be improved.

[0030] The effects according to the embodiments are not limited to those exemplified above, and a wider variety of effects are included in this specification. Brief explanation of the drawing

[0031] FIG. 1 is a schematic plan view of a display device according to one embodiment. FIG. 2 is a plan view showing one pixel of a display device according to one embodiment. Figure 3 is a cross-sectional view showing an example of cutting along the line I-I' of Figure 2. FIG. 4 is a schematic diagram of a light-emitting element according to one embodiment. FIG. 5 is a side view showing an example of the light-emitting element of FIG. 4. FIG. 6 is a schematic diagram of a light-emitting element according to another embodiment. Figure 7 is a side view showing an example of the light-emitting element of Figure 6. Figure 8 is a side view showing another example of the light-emitting element of Figure 6. FIG. 9 is a planar arrangement diagram showing the relative planar arrangement of the first and second electrodes, the first and second contact electrodes, the light-emitting element, and the second insulating layer. FIG. 10 is an enlarged cross-sectional view showing an example of an enlarged area A of FIG. 3. FIG. 11 is an enlarged cross-sectional view illustrating the direction of propagation of light emitted from a light-emitting element. FIG. 12 is an enlarged cross-sectional view showing another example of region A of FIG. 3 enlarged. FIG. 13 is an enlarged cross-sectional view showing another example of region A of FIG. 3 enlarged. FIG. 14 is a cross-sectional view showing another example cut along the line I-I' of FIG. 2. Specific details for implementing the invention

[0032] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0033] Elements or layers are placed on another element or layer.

[0034] The term includes all cases where another layer or other element is interposed directly above or in the middle of another element. Throughout the specification, the same reference numerals refer to the same components.

[0035] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may also be the second component within the technical scope of the present invention.

[0036] Hereinafter, embodiments will be described with reference to the attached drawings.

[0037] FIG. 1 is a schematic plan view of a display device according to one embodiment.

[0038] Referring to FIG. 1, the display device (10) displays a video or a still image. The display device (10) may refer to any electronic device that provides a display screen. For example, a television, laptop, monitor, billboard, Internet of Things, mobile phone, smartphone, tablet PC (Personal Computer), electronic watch, smart watch, watch phone, head-mounted display, mobile communication terminal, electronic notebook, e-book, PMP (Portable Multimedia Player), navigation, game console, digital camera, camcorder, etc. that provide a display screen may be included in the display device (10).

[0039] The display device (10) includes a display panel that provides a display screen. Examples of display panels include an inorganic light-emitting diode display panel, an organic light-emitting diode display panel, a quantum dot light-emitting diode display panel, a plasma display panel, a field emission display panel, etc. In the following examples, an inorganic light-emitting diode display panel is used as an example of a display panel, but it is not limited thereto, and if the same technical concept is applicable, it can be applied to other display panels.

[0040] In the drawings of the embodiments describing the display device (10), a first direction (DR1), a second direction (DR2), and a third direction (DR3) are defined. The first direction (DR1) and the second direction (DR2) may be directions perpendicular to each other within a single plane. The third direction (DR3) may be a direction perpendicular to the plane where the first direction (DR1) and the second direction (DR2) are located. The third direction (DR3) is perpendicular to each of the first direction (DR1) and the second direction (DR2). In the embodiments describing the display device (10), the third direction (DR3) represents the thickness direction (or display direction) of the display device (10).

[0041] The display device (10) may have a rectangular shape that includes a long side and a short side where the first direction (DR1) in the plane is longer than the second direction (DR2). The corners where the long and short sides of the display device (10) in the plane may be right angles, but are not limited thereto, and may have a rounded curved shape. The shape of the display device (10) is not limited to the examples provided and may be varied in many ways. For example, the display device (10) may have other shapes such as a square in the plane, a square with rounded corners (vertices), other polygons, circles, etc.

[0042] The display surface of the display device (10) may be positioned on one side of the third direction (DR3), which is the thickness direction. Unless otherwise noted in the embodiments describing the display device (10), "top" indicates the display direction toward one side of the third direction (DR3), and "top surface" indicates the surface facing toward one side of the third direction (DR3). Additionally, "bottom" indicates the direction opposite to the display direction toward the other side of the third direction (DR3), and "bottom surface" refers to the surface facing toward the other side of the third direction (DR3). Furthermore, "left," "right," "top," and "bottom" indicate the direction when the display device (10) is viewed from a plane. For example, "right" indicates one side of the first direction (DR1), "left" indicates the other side of the first direction (DR1), "top" indicates one side of the second direction (DR2), and "bottom" indicates the other side of the second direction (DR2).

[0043] The display device (10) may include a display area (DPA) and a non-display area (NDA). The display area (DPA) is an area where the screen can be displayed, and the non-display area (NDA) is an area where the screen is not displayed.

[0044] The shape of the display area (DPA) can follow the shape of the display device (10). For example, the shape of the display area (DPA) may have a planar rectangular shape similar to the overall shape of the display device (10). The display area (DPA) may generally occupy the center of the display device (10).

[0045] The display area (DPA) may include a plurality of pixels (PX). The plurality of pixels (PX) may be arranged in a matrix direction. The shape of each pixel (PX) may be a planar rectangle or a square. In an exemplary embodiment, each pixel (PX) may include a plurality of light-emitting elements made of inorganic particles.

[0046] A non-display area (NDA) may be placed around a display area (DPA). The non-display area (NDA) may surround the display area (DPA) in whole or in part. The non-display area (NDA) may form the bezel of the display device (10).

[0047] FIG. 2 is a plan view showing one pixel of a display device according to one embodiment. FIG. 3 is a cross-sectional view showing one example cut along the line I-I' of FIG. 2.

[0048] Referring to FIG. 2, each pixel (PX) of the display device (10) may include a light-emitting region (EMA) and a non-light-emitting region (not shown). The light-emitting region (EMA) is a region where light emitted from a light-emitting element (ED) is emitted, and the non-light-emitting region can be defined as a region where light is not emitted because the light emitted from the light-emitting element (ED) does not reach.

[0049] The light-emitting region (EMA) may include a region where a light-emitting element (ED) is placed and an adjacent region. Additionally, the light-emitting region may further include a region where light emitted from the light-emitting element (ED) is reflected or refracted by another member and emitted.

[0050] Each pixel (PX) may further include a first region (CBA) disposed in a non-emissive region. The first region (CBA) may be disposed above the emitting region (EMA) within a pixel (PX) (or on one side of the second direction (DR2)). The first region (CBA) may be disposed between the emitting regions (EMA) of adjacent pixels (PX) disposed in the second direction (DR2).

[0051] The first region (CBA) may be a region where electrodes (210, 220) included in each pixel (PX) adjacent to each other along the second direction (DR2) are separated from each other. The electrodes (210, 220) placed for each pixel (PX) are separated from each other in the first region (CBA), and a portion of the electrodes (210, 220) placed for each pixel (PX) may be placed in the first region (CBA). A light-emitting element (ED) may not be placed in the first region (CBA).

[0052] Referring to FIGS. 2 and 3, the display device (10) may include a substrate (SUB), a circuit element layer (PAL) disposed on the substrate (SUB), and a light-emitting element layer disposed on the circuit element layer (PAL). The light-emitting element layer may include a first bank (400), first and second electrodes (210, 220), a second bank (600), a light-emitting element (ED), first and second contact electrodes (710, 720), and a plurality of insulating layers (510, 520, 530, 540).

[0053] The substrate (SUB) may be an insulating substrate. The substrate (SUB) may be made of an insulating material such as glass, quartz, or polymer resin. The substrate (SUB) may be a rigid substrate, but it may also be a flexible substrate capable of bending, folding, rolling, etc.

[0054] A circuit element layer (PAL) may be disposed on a substrate (SUB). The circuit element layer (PAL) may include at least one transistor, etc., to drive a light-emitting element layer.

[0055] The first bank (400) may be placed on the circuit element layer (PAL). Although not shown in the drawing, the circuit element layer (PAL) may include a via layer, and the first bank (400) may be placed on the via layer of the circuit element layer (PAL).

[0056] The first bank (400) may include a shape extending in a second direction (DR2) within each pixel (PX) on a plane. The first bank (400) may include a first sub-bank (410) and a second sub-bank (420) spaced apart from each other. The spaced-apart space formed by the first sub-bank (410) and the second sub-bank (420) spaced apart from each other may provide an area where a plurality of light-emitting elements (ED) are arranged.

[0057] The first and second sub-banks (410, 420) may have a structure in which at least a portion protrudes with respect to the upper surface of the substrate (SUB). The protruding portions of the first and second sub-banks (410, 420) may have inclined sides. By including inclined sides, the first and second sub-banks (410, 420) may serve to change the direction of propagation of light emitted from the light-emitting element (ED) and traveling toward the sides of the first and second sub-banks (410, 420) to an upward direction (e.g., display direction).

[0058] The first electrode (210) may be placed on the first sub-bank (410). The first electrode (210) may be extended in a second direction (DR2) in a planar manner to overlap with a portion of the second bank (600) extended in the first direction (DR1). The first electrode (210) may be electrically connected to the circuit element layer (PAL) through the first contact hole (CT1).

[0059] The first electrode (210) may be positioned to cover the upper surface and inclined side of the first sub-bank (410). The first electrode (210) may be positioned on the first sub-bank (410) to cover the first sub-bank (410) in a third direction (or thickness direction of the substrate (SUB), DR3).

[0060] The second electrode (220) may be placed on the second sub-bank (420). The second electrode (220) may be placed spaced apart from the first electrode (210). The second electrode (220) may be extended in a planar second direction (DR2) to overlap with a portion of the second bank (600) extended in the first direction (DR1). The second electrode (220) may be electrically connected to the circuit element layer (PAL) through the second contact hole (CT2).

[0061] The second electrode (220) may be positioned to cover the upper surface and inclined side of the second sub-bank (420). The second electrode (220) may be positioned on the second sub-bank (420) to cover the second sub-bank (420) in a third direction (or thickness direction of the substrate (SUB), DR3).

[0062] The first electrode (210) and the second electrode (220) are each extended outwardly on the first sub-bank (410) and the second sub-bank (420), respectively, and may also be partially disposed in the spaced-apart area formed where the first sub-bank (410) and the second sub-bank (420) are spaced apart from each other. In the spaced-apart area formed where the first sub-bank (410) and the second sub-bank (420) are spaced apart from each other, the first electrode (210) and the second electrode (220) may be spaced apart from each other.

[0063] The first and second electrodes (210, 220) are each electrically connected to light-emitting elements (EDs), and a predetermined voltage may be applied so that the light-emitting elements (EDs) emit light. For example, a plurality of electrodes (210, 220) are electrically connected to a light-emitting element (ED) placed between the first sub-bank (410) and the second sub-bank (420) through contact electrodes (710, 720) described later, and an electrical signal applied to the electrodes (210, 220) can be transmitted to the light-emitting element (ED) through the contact electrodes (710, 720).

[0064] The first and second electrodes (210, 220) may each include a highly reflective conductive material. For example, the first and second electrodes (210, 220) may each include a metal such as silver (Ag), copper (Cu), or aluminum (Al) as a highly reflective material, or an alloy including aluminum (Al), nickel (Ni), or lanthanum (La). The first and second electrodes (210, 220) may each reflect light emitted from the light-emitting element (ED) and traveling toward the side of the first bank (400) toward a display direction (e.g., a third direction (DR3)).

[0065] However, the first and second electrodes (210, 220) may each further include a transparent conductive material, without being limited thereto. For example, the first and second electrodes (210, 220) may each include a material such as ITO, IZO, ITZO, etc. In some embodiments, the first and second electrodes (210, 220) may each form a structure in which a transparent conductive material and a metal layer with high reflectivity are each stacked one or more times, or may be formed as a single layer including these. For example, the first and second electrodes (210, 220) may each have a stacked structure such as ITO / Ag / ITO / , ITO / Ag / IZO, or ITO / Ag / ITZO / IZO.

[0066] The first insulating layer (510) is disposed on a plurality of electrodes (210, 220) and a first bank (400). The first insulating layer (510) is disposed on the first electrode (210) and the second electrode (220), but may be disposed to expose at least a portion of the first electrode (210) and the second electrode (220).

[0067] In an exemplary embodiment, the first insulating layer (510) may have an opening formed therein that exposes a portion of the upper surface of the first electrode (210) disposed on the first sub-bank (410) and a portion of the upper surface of the second electrode (220) disposed on the second sub-bank (420). The first contact electrode (710) described below may contact the first electrode (210) through an opening penetrating the first insulating layer (510), and the second contact electrode (720) may contact the second electrode (220) through an opening penetrating the first insulating layer (510).

[0068] The first insulating layer (510) can protect the first electrode (210) and the second electrode (220) while simultaneously insulating them from each other. Specifically, the first insulating layer (510) can be disposed on the first electrode (210) and the second electrode (220), including an area between the first electrode (210) and the second electrode (220), to insulate them from each other. Additionally, it can prevent the light-emitting element (ED) disposed on the first insulating layer (510) from being damaged by direct contact with other components.

[0069] The second bank (600) is placed on the first insulating layer (510). The second bank (600) may be arranged in a grid pattern including portions extending in the first direction (DR1) and the second direction (DR2) in a planar manner. The second bank (600) may be formed to have a greater height than the first bank (400). The second bank (600) may perform the function of preventing ink containing the light-emitting element (ED) from overflowing into adjacent pixels (PX) during an inkjet printing process for aligning the light-emitting element (ED) during the manufacturing process of the display device (10).

[0070] The light-emitting element (ED) may have a shape that extends in one direction. The light-emitting element (ED) may have a different diameter at one end positioned on one side of the one direction of extension of the light-emitting element (ED) and at the other end positioned on the other side of the one direction. The light-emitting element (ED) may include an active layer (330) and emit light of a specific wavelength band according to an electrical signal applied through the first electrode (210) and the second electrode (220). The active layer (330) of the light-emitting element (ED) may be positioned adjacent to the end with the larger diameter among the two ends of the light-emitting element (ED). A detailed description of the shape of the light-emitting element (ED) will be described later with reference to other drawings.

[0071] A light-emitting element (ED) may be disposed on a first insulating layer (510) between a first sub-bank (410) and a second sub-bank (420). The light-emitting element (ED) may be disposed on the first insulating layer (510) such that both ends in the direction of extension of the light-emitting element (ED) are placed on the first electrode (210) and the second electrode (220), respectively. The direction in which the light-emitting element (ED) is extended may be substantially perpendicular to the direction in which each electrode (210, 220) is extended. However, not limited thereto, some of the plurality of light-emitting elements (ED) may be disposed such that the direction in which the light-emitting element (ED) is extended is substantially perpendicular to the direction in which the first and second electrodes (210, 220) are extended, and other parts of the plurality of light-emitting elements (ED) may be disposed such that the direction in which the light-emitting element (ED) is extended is oblique to the direction in which the first and second electrodes (210, 220) are extended.

[0072] The second insulating layer (520) may be partially disposed on the light-emitting element (ED). The second insulating layer (520) may be disposed to partially wrap the outer surface of the light-emitting element (ED), but not to cover both ends of the light-emitting element (ED). The second insulating layer (520) may be disposed to expose at least a portion of the active layer (330) of the light-emitting element (ED). That is, the second insulating layer (520) may not overlap with at least a portion of the active layer (330) in the third direction (DR3).

[0073] A portion of the second insulating layer (520) disposed on the light-emitting element (ED) may be disposed extending in a second direction (DR2) on the planar first insulating layer (510) to form a linear or island pattern within each pixel (PX). The second insulating layer (520) can protect the light-emitting element (ED) and, at the same time, serve to fix the light-emitting element (ED) during the manufacturing process of the display device (10).

[0074] The first contact electrode (710) may be placed on the first electrode (210). The first contact electrode (710) may have a shape extending in one direction. The first contact electrode (710) may have a shape extending in a second direction (DR2). The first contact electrode (710) may form a stripe-shaped pattern within the light-emitting region (EMA) of each pixel (PX).

[0075] The first contact electrode (710) may be in contact with the first electrode (210) and one end of the light-emitting element (ED). The first contact electrode (710) may be placed on the first electrode (210), so that a portion of the first electrode (210) is in contact with one side of the first electrode (210) exposed by the first insulating layer (510), and another portion of the first electrode is in contact with one end of the light-emitting element (ED). By contacting the one end of the light-emitting element (ED) and the first electrode (210) respectively, the first contact electrode (710) may serve to electrically connect the light-emitting element (ED) and the first electrode (210). The first contact electrode (710) may be extended from one end of the light-emitting element (ED) toward the second insulating layer (520) and may also be placed on a portion of the second insulating layer (520).

[0076] The second contact electrode (720) may be placed on the second electrode (220). The second contact electrode (720) may have a shape extending in one direction. The second contact electrode (720) may have a shape extending in a second direction (DR2). The second contact electrode (720) may form a stripe pattern within the light-emitting region (EMA) of each pixel (PX). The second contact electrode (720) may be placed so as to be spaced apart from the first contact electrode (710) in the first direction (DR1).

[0077] The second contact electrode (720) may contact the second electrode (220) and the other end of the light-emitting element (ED). The second contact electrode (720) may be placed on the second electrode (220), so that a portion of the second electrode (220) contacts one side of the second electrode (220) exposed by the first insulating layer (510), and a portion of the second electrode contacts the other end of the light-emitting element (ED). By contacting the other end of the light-emitting element (ED) and the second electrode (220) respectively, the second contact electrode (720) may serve to electrically connect the light-emitting element (ED) and the second electrode (220). The second contact electrode (720) may extend from the other end of the light-emitting element (ED) toward the third insulating layer (530) described later and may also be placed on a portion of the third insulating layer (530).

[0078] The first and second contact electrodes (710, 720) may each include a conductive material. For example, they may include ITO, IZO, ITZO, aluminum (Al), etc. As an example, the first and second contact electrodes (710, 720) may each include a transparent conductive material, but are not limited thereto.

[0079] A third insulating layer (530) is disposed on the first contact electrode (710). The third insulating layer (530) may be disposed to cover the first contact electrode (710). One end surface of the third insulating layer (530) and the second insulating layer (520) facing the second sub-bank (420) may be aligned parallel to each other.

[0080] The third insulating layer (530) can electrically insulate the first contact electrode (710) and the second contact electrode (720) from each other. The third insulating layer (530) is positioned to cover the first contact electrode (710), but may not be positioned on the other end of the light-emitting element (ED) so that the light-emitting element (ED) can come into contact with the second contact electrode (720).

[0081] The first contact electrode (710) and the second contact electrode (720) may be placed on different layers. A portion of the first contact electrode (710) may be placed directly on the second insulating layer (520) which is placed on the light-emitting element (ED), and a portion of the second contact electrode (720) may be placed directly on the third insulating layer (530), so that the third insulating layer (530) may be interposed between the first contact electrode (710) and the second contact electrode (720).

[0082] The fourth insulating layer (540) can be placed over the entire surface of the substrate (SUB). The fourth insulating layer (540) can function to protect the external environment of the components placed on the substrate (SUB).

[0083] FIG. 4 is a schematic diagram of a light-emitting element according to one embodiment. FIG. 5 is a side view showing an example of the light-emitting element of FIG. 4. FIG. 5 is a cross-section of the light-emitting element (ED) cut along one direction (X), which is the extension direction (X) of the light-emitting element (ED).

[0084] Referring to FIG. 4, the light-emitting element (ED) is a particle-shaped element and may have a shape extended in one direction (X). The light-emitting element (ED) may have a columnar shape, a rod shape, or a frustum shape. In one embodiment, the light-emitting element (ED) may have a frustum shape or a polygonal frustum shape. The length of the light-emitting element (ED) is greater than the diameter of the light-emitting element (ED), and the aspect ratio may be from 6:5 to 100:1, but is not limited thereto.

[0085] The light-emitting element (ED) may have a size ranging from a nanometer scale (1 nm or more and less than 1 µm) to a micrometer scale (1 µm or more and less than 1 mm). In one embodiment, the light-emitting element (ED) may have both a diameter and a length of a nanometer scale or both of micrometer scales. In some other embodiments, the diameter of the light-emitting element (ED) may have a size of a nanometer scale, while the length of the light-emitting element (ED) may have a size of a micrometer scale. In some embodiments, some of the light-emitting elements (ED) may have a diameter and / or length of a nanometer scale, while other parts of the light-emitting elements (ED) may have a diameter and / or length of a micrometer scale.

[0086] In one embodiment, the light-emitting element (ED) may be an inorganic light-emitting diode. Specifically, the light-emitting element (ED) may include a semiconductor layer doped with any conductivity type (e.g., p-type or n-type) impurity. The semiconductor layer receives an electrical signal applied from an external power source and can emit it as light of a specific wavelength range.

[0087] A light-emitting element (ED) may have a shape that extends in one direction (X) and has a diameter (or width) that varies along said one direction (X). The diameter of the light-emitting element (ED) may increase or decrease along said one direction (X). In an exemplary embodiment, the light-emitting element (ED) may have a shape in which its diameter decreases along said one direction (X). Because the light-emitting element (ED) has a shape in which its diameter (or width) decreases along said one direction (X), the diameter (or width) of one end and the other end of the light-emitting element (ED) in said one direction (X) may be different from each other.

[0088] In the drawings (specifically, FIGS. 5, 7, and 8) describing the cross-sectional shape of the light-emitting element (ED), one direction (X) and another direction (Y) are defined. One direction (X) is the extension direction of the light-emitting element (ED), and the other direction (Y) may be a direction that intersects the central part of the light-emitting element (ED) perpendicularly to the one direction (X).

[0089] In the embodiments describing the light-emitting element (ED) below, unless otherwise noted, "upper side" refers to the side where the second semiconductor layer (320), described later, is positioned with respect to the active layer (330) in one direction (X), which is the extension direction of the light-emitting element (ED), and "upper surface" refers to the surface facing one side in one direction (X). Additionally, "lower side" refers to the other side in the opposite direction of one direction (X), and "lower surface" refers to the surface facing the other side in one direction (X).

[0090] The light-emitting element (ED) may include a first surface (S1), a second surface (S2), and a third surface (S3). The first surface (S1) is one end surface (S1) of the light-emitting element (ED), the second surface (S2) is the other end surface (S2) of the light-emitting element (ED), and the third surface (S3) may be a side surface of the light-emitting element (ED) connecting the first surface (S1) and the second surface (S2), or an outer surface of the light-emitting element (ED) extended in one direction (X). Hereinafter, in describing the shape of the light-emitting element (ED), the first surface (S1) may also be referred to as the top surface (S1), the second surface (S2) as the bottom surface (S2), and the third surface (S3) as the side surface (S3).

[0091] The first diameter (W1) of the first surface (S1) of the light-emitting element (ED) may differ from the second diameter (W2) of the second surface (S2). The second diameter (W2) of the second surface (S2) may be larger than the first diameter (W1) of the first surface (S1), and the third surface (S3) may have a slanted shape. The third surface (S3) may be tilted at an acute angle with respect to the second surface (S2). The light-emitting element (ED) may have a taper angle formed so that the first diameter (W1) of the first surface (S1), which is the upper surface (S1), is smaller than the second diameter (W2) of the second surface (S2), which is the lower surface (S2), thus having a truncated cone shape.

[0092] A light-emitting element (ED) according to one embodiment may include a light-emitting element core (300) extending in one direction (X). The light-emitting element (ED) may further include an insulating film (380) covering the outer surface of the light-emitting element core (300).

[0093] The light-emitting element core (300) may have a shape that extends along one direction (X), which is the extension direction of the light-emitting element (ED). The shape of the light-emitting element core (300) may follow the shape of the light-emitting element (ED). The light-emitting element core (300) may have a shape that extends along one direction (X) similarly to the shape of the light-emitting element (ED), but has a shape in which its diameter (or width) changes along one direction (X). For example, the light-emitting element core (300) may have a truncated cone shape by having a diameter that decreases along one direction (X).

[0094] The light-emitting element core (300) may include a first semiconductor layer (310), an active layer (330), a second semiconductor layer (320), and an electrode layer (370) that are sequentially stacked in one direction (X).

[0095] The first semiconductor layer (310) may be an n-type semiconductor having a first conductivity type. The first semiconductor layer (310) may be doped with a first conductivity type dopant, and as an example, the first conductivity type dopant may be Si, Ge, Sn, etc. When the light-emitting element (ED) emits light in the blue or green wavelength range, the first semiconductor layer (310) may include a semiconductor material having a composition ratio of AlxGayIn(1-xy)N (where 0≤x≤1, 0≤y≤1, 0≤x+y≤1). In an exemplary embodiment, the first semiconductor layer (310) may be n-GaN doped with n-type Si.

[0096] The first semiconductor layer (310) may have a shape that extends along one direction (X). The first semiconductor layer (310) may have a diameter that varies along one direction (X). The diameter of the first semiconductor layer (310) may decrease along one direction (X). However, it is not limited thereto, and the diameter of the first semiconductor layer (310) may have a generally uniform diameter along one direction (X). The first semiconductor layer (310) may have a diameter that is greater than or equal to the maximum diameter of the second semiconductor layer (320) and the active layer (330) described later.

[0097] The first semiconductor layer (310) may include a first surface, a second surface, and a side facing the active layer (330). The second surface of the first semiconductor layer (310) may face the first surface of the first semiconductor layer (310). In the drawing, the first surface of the first semiconductor layer (310) may also be referred to as the upper surface, and the second surface as the lower surface.

[0098] As the diameter of the first semiconductor layer (310) decreases along one direction (X), the diameter of the upper surface of the first semiconductor layer (310) is smaller than the diameter of the lower surface, and the side surface may have a slanted shape. The side surface of the first semiconductor layer (310) may be inclined at an acute angle with respect to the lower surface of the first semiconductor layer (310). Although not limited thereto, the diameter of the lower surface of the first semiconductor layer (310) may have a range of 800 nm to 1000 nm.

[0099] The second semiconductor layer (320) may be disposed on the first semiconductor layer (310). The second semiconductor layer (320) may be disposed spaced apart from the first semiconductor layer (310) in the extension direction (X) of the light-emitting element (ED).

[0100] The second semiconductor layer (320) may be a p-type semiconductor having a second conductivity type. The second semiconductor layer (320) may be doped with a second conductivity type dopant, and as an example, the second conductivity type dopant may be Mg, Zn, Ca, Se, Ba, etc. When the light-emitting element (ED) emits light in the blue or green wavelength range, the second semiconductor layer (320) may include a semiconductor material having a composition ratio of AlxGayIn(1-xy)N (where 0≤x≤1, 0≤y≤1, 0≤x+y≤1). In an exemplary embodiment, the second semiconductor layer (320) may be p-GaN doped with p-type Mg.

[0101] The second semiconductor layer (320) may have a shape that extends along one direction (X). The second semiconductor layer (320) may have a diameter that varies along one direction (X). The diameter of the second semiconductor layer (320) may decrease along one direction (X). However, it is not limited thereto, and the diameter of the second semiconductor layer (320) may have a generally uniform diameter along one direction (X).

[0102] The second semiconductor layer (320) may include a first surface, a second surface, and a side facing the electrode layer (370). The second surface of the second semiconductor layer (320) may face the first surface of the active layer (330). In the drawing, the first surface of the second semiconductor layer (320) may also be referred to as the upper surface, and the second surface as the lower surface.

[0103] As the diameter of the second semiconductor layer (320) decreases along one direction (X), the diameter of the upper surface of the second semiconductor layer (320) is smaller than the diameter of the lower surface, and the side surface may have a slanted shape. The side surface of the second semiconductor layer (320) may be inclined at an acute angle with respect to the lower surface of the second semiconductor layer (320). Although not limited thereto, the diameter of the upper surface of the first semiconductor layer (310) may have a range of 300 nm to 400 nm.

[0104] The active layer (330) may be disposed between the first semiconductor layer (310) and the second semiconductor layer (320). The active layer (330) may be interposed between the first semiconductor layer (310) and the second semiconductor layer (320). The active layer (330) may include a material having a single or multiple quantum well structure. The active layer (330) may emit light by the coupling of electron-hole pairs according to an electrical signal applied through the first semiconductor layer (310) and the second semiconductor layer (320). However, it is not limited thereto, and the active layer (330) may have a structure in which semiconductor materials of a type with a large band gap energy and semiconductor materials of a small band gap energy are alternately stacked, and may include different group 3 to group 5 semiconductor materials depending on the wavelength range of the emitted light.

[0105] When the light-emitting element (ED) emits light in the blue or green wavelength range, the light-emitting layer (330) may include materials such as AlGaN, AlGaInN, etc. For example, the light-emitting layer (330) may include AlGaInN as the quantum layer and AlInN as the well layer to emit blue light with a central wavelength range of 450 nm to 495 nm.

[0106] The light emitted from the active layer (330) can be emitted not only on the outer surface in the longitudinal direction of the light-emitting element (ED), but also on both sides. The light emitted from the active layer (330) is not limited to a single direction.

[0107] The active layer (330) may include a one-sided surface, a other-sided surface, and a side facing the second semiconductor layer (320). The other-sided surface of the active layer (330) may face the one-sided surface of the active layer (330). In the drawing, the one-sided surface of the active layer (330) may be referred to as the upper surface, and the other-sided surface as the lower surface.

[0108] The active layer (330) may have a diameter that varies along one direction (X). The diameter of the active layer (330) may decrease along one direction (X). As the diameter of the active layer (330) decreases along one direction (X), the diameter of the upper surface of the active layer (330) may be smaller than the diameter of the lower surface, and the side surface may have a slanted shape. The side surface of the active layer (330) may be inclined at an acute angle with respect to the lower surface of the active layer (330). Although not limited thereto, the diameter of the upper surface of the active layer (330) may have a range of 450 nm to 500 nm, and the diameter of the lower surface may have a range of 550 nm to 650 nm.

[0109] The light emitted from the active layer (330) can be emitted not only at both end surfaces in the extension direction (X) of the light-emitting element (ED), but also on both sides. That is, the directionality of the light emitted from the active layer (330) to the outside of the light-emitting element (ED) is not limited to a single direction.

[0110] The electrode layer (370) may be disposed on the second semiconductor layer (320). The electrode layer (370) may be an ohmic contact electrode. However, it is not limited thereto and may be a Schottky contact electrode.

[0111] The electrode layer (370) can be placed between the second semiconductor layer (320) and the electrode to reduce resistance when the contact electrodes (710, 720) are electrically connected to both ends of the light-emitting element (ED) to apply an electrical signal to the first semiconductor layer (310) and the second semiconductor layer (320). The electrode layer (370) may include a conductive metal. For example, the electrode layer (370) may include at least one of aluminum (Al), titanium (Ti), indium (In), gold (Au), silver (Ag), ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), and ITZO (Indium Tin-Zinc Oxide). Additionally, the electrode layer (370) may include an n-type or p-type doped semiconductor material.

[0112] One end surface of the light-emitting element core (300) may be the upper surface of the electrode layer (370) or the second semiconductor layer (320), and the other end surface may be the lower surface of the first semiconductor layer (310). The maximum diameter of one end of the light-emitting element core (300) may be greater than the minimum diameter of the other end of the light-emitting element core (300). The cross-sectional shape of the light-emitting element core (300) cut along one direction (X) may be a trapezoidal shape. In an exemplary embodiment, the cross-sectional shape of the light-emitting element core (300) may include a shape symmetric with respect to a first reference line (Lx) that crosses the center of the light-emitting element (ED) in one direction (X). That is, the light-emitting element core (300) or the light-emitting element (ED) may have a cross-sectional shape that is an isosceles trapezoid formed such that both sides are inclined at the same angle. However, not limited thereto, the light-emitting element core (300) or the light-emitting element (ED) may have a cross-sectional shape in which both sides are inclined at different angles to each other, and the first surface (S1) and the second surface (S2) of the light-emitting element core (300) or the light-emitting element (ED) may not be parallel to each other, and at least one of the first surface (S1) and the second surface (S2) may be formed to be inclined with respect to one direction (X).

[0113] In the light-emitting element core (300), the active layer (330) may be positioned adjacent to the end with the larger diameter among the two ends of the light-emitting element core (300). Specifically, the active layer (330) may include one surface facing the first surface (S1) of the light-emitting element (ED) and the other surface facing the second surface (S2) of the light-emitting element (ED). For example, one surface of the active layer (330) may be the upper surface and the other surface may be the lower surface.

[0114] A first distance (d1) in one direction (X) between a first surface (S1) of a light-emitting element (ED) having a first diameter (W1) and one surface of an active layer (330) may be different from a second distance (d2) in one direction (X) between a second surface (S2) of a light-emitting element (ED) having a second diameter (W2) larger than the first diameter (W1) and the other surface of an active layer (330). The first distance (d1) may be larger than the second distance (d2). As the active layer (330) is formed such that the first distance (d1) is larger than the second distance (d2), the active layer (330) may be located on the side with the larger diameter within the light-emitting element (ED).

[0115] In other words, the active layer (330) may be located on one side of the first direction (X) with respect to a second reference line (Ly) that crosses the center of the light-emitting element (ED) in the other direction (Y) perpendicular to the first direction (X). The active layer (330) may be positioned adjacent to the second end side having a second diameter (W2) that is larger than the first diameter (W1) with respect to the second reference line (Ly).

[0116] The insulating film (380) may be arranged to surround the light-emitting element core (300). The insulating film (380) is formed to surround the sides of each member of the light-emitting element core (300) and may serve to protect each member of the light-emitting element core (300), such as the first semiconductor layer (310), the second semiconductor layer (320), and the active layer (330).

[0117] The insulating film (380) is arranged to surround the outer surface of the plurality of semiconductor layers and electrode layers described above. In an exemplary embodiment, the insulating film (380) is arranged to surround the outer surface of at least the active layer (330) of the light-emitting element core (300), and the light-emitting element (ED) may extend in one direction (X) where it is extended.

[0118] The insulating film (380) may have a generally uniform thickness along one direction (X). The thickness of the insulating film (380) may be in the range of 10 nm to 1.0 µm, but is not limited thereto. Preferably, the thickness of the insulating film (380) may be in the range of 20 nm to 100 nm.

[0119] The insulating film (380) may include materials having insulating properties. For example, it may include silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy), aluminum nitride (AlN), aluminum oxide (AlOx), etc. The insulating film (380) may have a single film or a multilayer structure in which the materials listed above are stacked. Since the insulating film (380) is made of materials having insulating properties, it can prevent an electrical short circuit that may occur when the active layer (330) comes into direct contact with the electrode through which an electrical signal is transmitted to the light-emitting element (ED). In addition, since the insulating film (380) protects the outer surface of the light-emitting element (ED) including the active layer (330), it can prevent a decrease in light-emitting efficiency.

[0120] In this embodiment, the active layer (330) of the light-emitting element (ED) may be positioned so as to be offset toward the end side with a larger diameter with respect to a second reference line (Ly) that crosses the central part of the light-emitting element (ED) in a direction (Y) perpendicular to the one direction (X) which is the extension direction of the light-emitting element (ED). For light-emitting elements (ED) having the same shape, the average diameter of the active layer (330) can be formed larger as the active layer (330) is positioned so as to be offset toward the end side with a larger diameter. Accordingly, the volume of the active layer (330) increases, and the light-emitting efficiency of the light-emitting element (ED) can be increased.

[0121] In addition, damage to the active layer (330) can be prevented by the etchant used in the process of vertically etching a plurality of semiconductor layers and electrode layers during the process of manufacturing a light-emitting device (ED). For example, a method for manufacturing a light-emitting device (ED) can form a plurality of semiconductor material layers, an active material layer, and an electrode material layer, and then etch them in one direction (X) to form a light-emitting device core (300) extended in one direction (X). Specifically, a first semiconductor material layer can be formed, an active material layer can be formed on the first semiconductor material layer, a second semiconductor material layer can be formed on the active material layer, and an electrode material layer can be formed on the second semiconductor material layer, and then etched in one direction (X) to form a light-emitting device core (300) extended in one direction (X). In this case, the thickness of the second semiconductor material layer can be formed thicker so that the first distance (d1) in one direction (X) between the first surface (S1) of the light-emitting element (ED) and one surface of the active layer (330) is greater than the second distance (d2) in one direction (X) between the second surface (S2) of the light-emitting element (ED) having a second diameter (W2) larger than the first diameter (W1) and the other surface of the active layer (330). Accordingly, the active material layer can be located relatively lower. During the process of manufacturing the light-emitting element (ED), in the process of etching the light-emitting element (ED), when the active material layer is etched by an etchant to form the active layer (330), the active material layer is positioned lower, so damage to the active layer (330) caused by the etchant can be reduced. Accordingly, damage to the side of the light-emitting element core (300) is reduced, and the quality of the light-emitting element (ED) can be improved.

[0122] FIG. 6 is a schematic diagram of a light-emitting element according to another embodiment. FIG. 7 is a side view showing an example of the light-emitting element of FIG. 6.

[0123] Referring to FIGS. 6 and 7, the light-emitting element (ED_1) according to the present embodiment differs from the light-emitting element (ED) of FIGS. 4 and 5 in that the first semiconductor layer (310_1) includes a plurality of sub-semiconductor layers (311, 312, 313), the second semiconductor layer (320_1) includes a plurality of sub-semiconductor layers (321, 322), and the active layer (330_1) contains phosphorus (P), which is another element. The light-emitting element (ED_1) according to the present embodiment can emit red light having a central wavelength band in the range of 600 nm to 750 nm. However, the central wavelength band of the red light is not limited to the range described above, and should be understood to include all wavelength ranges that can be recognized as red in the art.

[0124] Specifically, the first semiconductor layer (310_1) may include first to third sub-semiconductor layers (311, 312, 313). The first to third sub-semiconductor layers (311, 312, 313) may each be an n-type doped semiconductor having a first conductivity type.

[0125] The first sub-semiconductor layer (311) may include a semiconductor material having a composition ratio of InxGa(1-x)P (where 0≤x≤1). The first semiconductor layer (31') may be one or more of n-type doped GaP, InGaP, and InP. For example, the first sub-semiconductor layer (31') may be n-GaInP doped with n-type Si.

[0126] The second sub-semiconductor layer (312) may be disposed between the first sub-semiconductor layer (311) and the active layer (330_1). The second sub-semiconductor layer (311) may include a semiconductor material having a composition ratio of InxAlyGa(1-xy)P (where 0≤x≤1, 0≤y≤1, 0≤x+y≤1) as an n-type semiconductor layer. The second sub-semiconductor layer (312) may be one or more of n-type doped InAlGaP, GaP, AlGaP, InGaP, AlP, and InP. For example, the second sub-semiconductor layer (312) may be n-AlGaInP doped with n-type Si.

[0127] The third sub-semiconductor layer (313) may be disposed between the second sub-semiconductor layer (312) and the active layer (330_1). The third sub-semiconductor layer (313) may be an n-type semiconductor layer and may include a semiconductor material having a composition ratio of InxAl(1-x)P (where 0≤x≤1). The third sub-semiconductor layer (313) may be one or more of n-type doped AlInP, AlP, and InP. For example, the third sub-semiconductor layer (313) may be n-AlInP doped with n-type Si.

[0128] The second semiconductor layer (320_1) may include fourth and fifth sub-semiconductor layers (321, 322). The fourth and fifth sub-semiconductor layers (321, 322) may each be a p-type doped semiconductor having a second conductivity type.

[0129] The fourth sub-semiconductor layer (321) may be disposed between the active layer (330_1) and the electrode layer (370). The fourth sub-semiconductor layer (321) may include a semiconductor material having a composition ratio of InxAlyGa(1-xy)P (where 0≤x≤1, 0≤y≤1, 0≤x+y≤1) as a p-type semiconductor layer. The fourth sub-semiconductor layer (321) may be one or more of p-type doped InAlGaP, GaP, AlGaNP, InGaP, AlP, and InP. For example, the fourth sub-semiconductor layer (321) may be p-GaP doped with p-type Mg.

[0130] The fifth sub-semiconductor layer (322) may be disposed between the fourth sub-semiconductor layer (321) and the active layer (330_1). The fifth sub-semiconductor layer (322) may be a p-type semiconductor layer and may include a semiconductor material having a composition ratio of InxAl(1-x)P (where 0≤x≤1). The fifth sub-semiconductor layer (322) may be one or more of p-type doped AlInP, AlP, and InP. For example, the fifth sub-semiconductor layer (322) may be p-AlInP doped with p-type Mg.

[0131] Figure 8 is a side view showing another example of the light-emitting element of Figure 6.

[0132] Referring to FIG. 8, the light-emitting element (ED_2) according to the present embodiment differs from the light-emitting element (ED_1) of FIG. 6 in that the side of the active layer (330_2) protrudes outwardly more than the side of the fifth sub-semiconductor layer (322) located at the top and the third sub-semiconductor layer (313) located at the bottom.

[0133] The light-emitting element (ED_2) according to the present embodiment can be formed by the difference in the etching selectivity ratio of each semiconductor layer of the etchant used in the process of vertically etching a plurality of semiconductor layers and electrode layers during the process of manufacturing the light-emitting element (ED_2). For example, the method of manufacturing the light-emitting element (ED_2) may form a plurality of semiconductor material layers, an active material layer, and an electrode material layer, and then etch them in one direction (X) to form a light-emitting element core (300_2) extended in one direction (X). During the process of manufacturing the light-emitting element (ED_2), in the process of etching the light-emitting element (ED_2), the etching selectivity ratio of the plurality of semiconductor material layers and the active material layer for the same etchant is different, so that the light-emitting element (ED_2) having a shape in which the side of the active layer (330_2) protrudes more than the side of the semiconductor layer located above and below the active layer (330_2) can be manufactured as shown in FIG. 8.

[0134] FIG. 9 is a planar arrangement diagram showing the relative planar arrangement of the first and second electrodes, the first and second contact electrodes, the light-emitting element, and the second insulating layer. FIG. 10 is an enlarged cross-sectional view showing an example of an enlarged area A of FIG. 3.

[0135] Hereinafter, with reference to FIGS. 9 and FIGS. 10, the relative arrangement relationship between the active layer (330) of the light-emitting element (ED), the plurality of electrodes (210, 220), and the second insulating layer (520) disposed on the light-emitting element (ED) will be explained.

[0136] As described above, the light-emitting element (ED) may have different diameters at one end and the other end in one direction (X), which is the extension direction of the light-emitting element (ED). The light-emitting element (ED) may be placed on a first insulating layer (510) such that one end of the light-emitting element (ED) is placed on a first electrode (210) and the other end of the light-emitting element (ED) is placed on a second electrode (220).

[0137] Hereinafter, for convenience of explanation, one end (or first end) of the light-emitting element (ED) is referred to as the end on the side with the smaller diameter, as the first surface (S1, see FIG. 4) of the light-emitting element (ED) having a first diameter (W1, see FIG. 4), and the other end (or second end) of the light-emitting element (ED) is referred to as the end on the side with the larger diameter, as the second surface (S2, see FIG. 4) of the light-emitting element (ED) having a second diameter (W2, see FIG. 4) that is larger than the first diameter (W1). One end of the light-emitting element (ED) may be referred to as the first end, and the other end as the second end.

[0138] The first semiconductor layer (310), active layer (330), second semiconductor layer (320), and electrode layer (370) included in the semiconductor core (300) of the light-emitting element (ED) disposed on the first insulating layer (510) may be sequentially stacked along the opposite direction of the first direction (DR1). However, as the light-emitting element (ED) has a trapezoidal cross-sectional shape in which the diameters of the first end and the second end are different from each other, the respective boundary surfaces of the first semiconductor layer (310), active layer (330), second semiconductor layer (320), and electrode layer (370) may be inclined with respect to the first direction (DR1).

[0139] The active layer (330) of the light-emitting element (ED) may pass through the central part of the light-emitting element (ED) and be positioned on the second end side with respect to a cutting line perpendicular to the extension direction of the light-emitting element (ED). In an exemplary embodiment in which the first end of the light-emitting element (ED) where the electrode layer (370) is located is positioned on the first electrode (210) and the second end of the light-emitting element (ED) where the first semiconductor layer (310) is located is positioned on the second electrode (220), the second electrode (220) may overlap with the active layer (330) in the third direction (DR3). Specifically, the second electrode (220) may be positioned at the bottom of the light-emitting element (ED) to completely cover the active layer (330) of the light-emitting element (ED) from below. Although the drawing shows that the first end of the light-emitting element (ED) is positioned on the first electrode (210) and the second end is positioned on the second electrode (220), the arrangement relationship between both ends of the light-emitting element (ED) and the first and second electrodes (210, 220) is not limited thereto. For example, the first end of the light-emitting element (ED) may be positioned on the second electrode (220) and the second end may be positioned on the first electrode (210). In this case, the first electrode (210) may be positioned below the light-emitting element (ED) to completely cover the active layer (330) positioned on the second end side of the light-emitting element (ED) from below.

[0140] The second insulating layer (520) may be disposed on the light-emitting element (ED) to expose the first end and the second end of the light-emitting element (ED), respectively. The second insulating layer (520) may not overlap with at least a portion of the active layer (330) of the light-emitting element (ED) in the third direction (DR3). In an exemplary embodiment, the second insulating layer (520) may be disposed on the light-emitting element (ED) so as not to overlap with the active layer (330) of the light-emitting element (ED) in the third direction (DR3), thereby exposing the active layer (330) in the third direction (DR3).

[0141] The first contact electrode (710) and the second contact electrode (720) disposed on the second insulating layer (520) can each contact the first end and the second end of the light-emitting element (ED).

[0142] The first contact electrode (710) may contact the electrode layer (370) constituting the first surface (S1, see FIG. 4) of the light-emitting element (ED) on the first end of the light-emitting element (ED) where the electrode layer (370) or the second semiconductor layer (320) is located. Likewise, the second contact electrode (720) may contact the first semiconductor layer (310) constituting the second surface (S2, see FIG. 4) of the light-emitting element (ED) on the second end of the light-emitting element (ED) where the first semiconductor layer (310) is located.

[0143] FIG. 11 is an enlarged cross-sectional view illustrating the direction of propagation of light emitted from a light-emitting element.

[0144] Referring to FIG. 4 and FIG. 11, light emitted from the active layer (330) of the light-emitting element (ED) can be emitted not only to the first and second surfaces (S1, S2), which are the end surfaces in the extension direction of the light-emitting element (ED), but also to the third surface (S3), which is a side surface.

[0145] Hereinafter, for the convenience of explanation, the light emitted from the active layer (330) of the light-emitting element (ED) placed on the first insulating layer (510) will be described by classifying it into first to fourth lights (L1, L2, L3, L4) based on the direction of propagation.

[0146] The first light (L1) may be light emitted upward relative to the light-emitting element (ED). The first light (L1) may be emitted from the active layer (330) through the third surface (S3) of the light-emitting element (ED) located on the side of the fourth insulating layer (540).

[0147] As described above, the second insulating layer (520) can be arranged so as not to overlap with the active layer (330) in the third direction (DR3). By arranging the second insulating layer (520) and the active layer (330) so as not to overlap in the third direction (DR3), the ratio of light incident on the second insulating layer (520) among the light emitted from the active layer (330) can be reduced, thereby improving the light emission efficiency of the display device (10).

[0148] Specifically, when the second insulating layer (520) is arranged to overlap the active layer (330) and the third direction (DR3), most of the first light (L1) emitted from the active layer (330) and traveling toward the upper part of the display device (10) (or the third direction (DR3)) can be incident on the second insulating layer (520). In this case, the thickness of the second insulating layer (520) is formed to be greater than the diameter of the light-emitting element (ED) so that the second insulating layer (520) performs the role of fixing the light-emitting element (ED), and thus the light incident on the second insulating layer (520) may not easily pass through the second insulating layer (520) and be emitted to the outside. Additionally, the refractive index of the second insulating layer (520) is formed to be greater than the refractive index of another member or greater than the refractive index of air, so that light incident on the second insulating layer (520) cannot pass through the interface between the second insulating layer (520) and another member and can be partially reflected (total reflection) into the second insulating layer (520). That is, among the light emitted from the light-emitting element (ED), the light incident on the second insulating layer (520) is not easily emitted to the outside of the second insulating layer (520) due to the thickness or refractive index of the second insulating layer (520). Therefore, if the proportion of light incident on the second insulating layer (520) among the light emitted from the light-emitting element (ED) is high, the light emission efficiency of the display device (10) may be reduced. Accordingly, by arranging the active layer (330) of the light-emitting element (ED) and the second insulating layer (520) so as not to overlap in the third direction (DR3), the ratio of the first light (L1) emitted from the active layer (330) to the second insulating layer (520) is reduced, thereby improving the light emission efficiency of the display device (10).

[0149] The second light (L2) and the third light (L3) may be light emitted from both sides based on the light-emitting element (ED). The second light (L2) may generally be emitted through the first surface (S1) of the light-emitting element (ED), and the third light (L3) may generally be emitted through the second surface (S2) of the light-emitting element (ED). Although not shown in the drawing, the second light (L2) may pass through the first contact electrode (710) and the third insulating layer (530) placed on the first end side of the light-emitting element (ED) and be incident on the first electrode (210) placed on the first sub-bank (410). The second light (L2) incident on the first electrode (210) may be reflected from the upper surface of the first electrode (210) and its direction of travel may be changed to an upward direction (e.g., a display direction). Likewise, the third light (L3) can pass through the second contact electrode (720) placed on the second end side of the light-emitting element (ED) and be incident on the second electrode (220) placed on the second sub-bank (420). The third light (L3) incident on the second electrode (220) can be reflected from the upper surface of the second electrode (220) and its direction of travel can be changed to an upward direction (e.g., a display direction).

[0150] The fourth light (L4) may be light emitted downwards relative to the light-emitting element (ED). The fourth light (L4) may be emitted from the active layer (330) through the third surface (S3) of the light-emitting element (ED) located on the side of the first insulating layer (510).

[0151] As described above, the first electrode (210) or the second electrode (220) and the active layer (330) may be arranged to overlap in the third direction (DR3). In an exemplary embodiment, the second electrode (220) of the active layer (330) may overlap in the third direction (DR3). By arranging the second electrode (220) and the active layer (330) to overlap in the third direction (DR3), the light emission efficiency of the display device (10) can be improved by increasing the ratio of changing the direction of light traveling downward among the light emitted from the active layer (330) to the upward direction.

[0152] Specifically, when the active layer (330) is non-overlapping with both the first electrode (210) and the second electrode (220) in the third direction (DR3), most of the fourth light (L4) emitted from the active layer (330) and traveling downward (or in the opposite direction of the third direction (DR3)) is incident on the first insulating layer (510) and converted into other energy (e.g., thermal energy) and absorbed by the circuit element layer (PAL) or the first insulating layer (510) without being reflected. Accordingly, as a portion of the fourth light (L4) is converted into other energy and absorbed by other components of the display device (10), the proportion of light emitted from the light-emitting element (ED) in the upward direction is reduced, and the light emission efficiency of the display device (10) may be lowered. In contrast, when the active layer (330) of the light-emitting element (ED) is overlapped with the second electrode (220) in the third direction (DR3), the proportion of the fourth light (L4) traveling toward the second electrode (220) can be increased, and the fourth light (L4) traveling toward the second electrode (220) can be reflected from the upper surface of the second electrode (220) and its direction of travel can be changed to the upward direction. Accordingly, by arranging the active layer (330) of the light-emitting element (ED) and either the first or second electrode (210, 220) to overlap in the third direction (DR3), the proportion of the third light (L4) emitted from the active layer (330) that is incident on the first electrode (210) or the second electrode (220) is increased, thereby increasing the reflectance by the first and second electrodes (210, 220), and thus the light emission efficiency of the display device (10) can be improved.

[0153] In this embodiment, regarding one side of the active layer (330) facing the first side (S1) of the light-emitting element (ED) and the other side of the active layer (330) facing the second side (S2) of the light-emitting element (ED), the active layer (330) can be positioned such that the distance (d1) between the first side (S1) of the light-emitting element (ED) and one side of the active layer (330) is greater than the distance (d2) between the second side (S2) of the light-emitting element (ED) and the other side of the active layer (330). Accordingly, by positioning the active layer (330) within the light-emitting element (ED) so that it is positioned to one side rather than the center, the relative arrangement relationship between the first and second electrodes (210, 220) and the second insulating layer (520), which are positioned on the upper and lower parts of the light-emitting element (ED) placed on the substrate (SUB) of the display device (10), can be easily adjusted to improve the light-emitting efficiency of the display device (10). Additionally, by positioning the active layer (330) so that it is positioned toward the second end side having a second diameter larger than the first diameter, the average diameter of the active layer (330) becomes larger than when it is positioned toward the first end side having a smaller diameter, so the volume of the active layer (330) can be increased. Therefore, since the volume of the active layer (330) increases relative to the light-emitting element (ED) of the same shape, the light efficiency of the light-emitting element (ED) can be increased, and thus the light-emitting efficiency of the display device (10) can be improved.

[0154] Other embodiments are described below. In the following embodiments, redundant descriptions of configurations identical to those previously described will be omitted or simplified, and the explanation will focus on the differences.

[0155] FIG. 12 is an enlarged cross-sectional view showing another example of region A of FIG. 3 enlarged.

[0156] Referring to FIG. 12, the display device (10) according to the present embodiment differs from the embodiment of FIG. 10 in that the second insulating layer (520_1) overlaps with the active layer (330) of the light-emitting element (ED) in part and in the third direction (DR3).

[0157] Specifically, the second insulating layer (520_1) may be positioned to overlap a portion of the active layer (330) of the light-emitting element (ED) in a third direction (DR3) and to not overlap another portion of the light-emitting element (ED) in a third direction (DR3). The portion of the active layer (330) that overlaps with the second insulating layer (520_1) may have a smaller area or volume than the other portion of the active layer (330) that does not overlap with the second insulating layer (520_1). Therefore, even though the second insulating layer (520_1) is positioned to partially overlap with the active layer (330), the planar overlapping area is smaller than the non-overlapping area, so the proportion of light emitted from the active layer (330) and incident on the second insulating layer (520_1) may not be large. Therefore, the ratio of light emitted from the active layer (330) to the second insulating layer (520) can be reduced while fixing the light-emitting element (ED) more stably.

[0158] FIG. 13 is an enlarged cross-sectional view showing another example of region A of FIG. 3 enlarged.

[0159] Referring to FIG. 13, the display device (10) according to the present embodiment differs from the embodiment of FIG. 10 in that one of the plurality of electrodes (210_1, 220_1) does not completely cover the active layer (330) at the bottom of the light-emitting element (ED) but covers only a part of the area.

[0160] Specifically, the distance of the first electrode (210_1) and the second electrode (220_1) in the first direction (DR1) may be greater than the distance between the first electrode (210) and the second electrode (220) of FIG. 10. Accordingly, the second electrode (220_1) may not cover at least a portion of the active layer (330) at the bottom of the active layer (330). That is, the second electrode (220_1) may be positioned so as not to overlap with a portion of the active layer (330) in the third direction (DR3).

[0161] FIG. 14 is a cross-sectional view showing another example cut along the line I-I' of FIG. 2.

[0162] Referring to FIG. 14, the display device (10) according to the present embodiment differs from the embodiment of FIG. 3 in that the second contact electrode (720_1) is formed on the same layer as the first contact electrode (710) and the third insulating layer (530) is omitted.

[0163] Specifically, the first contact electrode (710) and the second contact electrode (720_1) may be placed directly on the second insulating layer (520). Although not limited thereto, the first contact electrode (710) and the second contact electrode (720_1) may be patterned and formed simultaneously by a single mask process. The first contact electrode (710) and the second contact electrode (720_1) may be spaced apart from each other on the second insulating layer (520) to expose a portion of the second insulating layer (520). The second insulating layer (520) exposed by the first contact electrode (710) and the second contact electrode (720_1) may come into contact with the fourth insulating layer (54) in the exposed area.

[0164] In this embodiment, even if the third insulating layer (530) is omitted, the display device (10) can perform the function of fixing the light-emitting element (ED) by the second insulating layer (520) containing an organic insulating material. In addition, since the first contact electrode (710) and the second contact electrode (720_1) are patterned and formed simultaneously by a single mask process, no additional mask process is required to form the first contact electrode (710) and the second contact electrode (720_1), thus improving process efficiency. This embodiment is identical to the embodiment of FIG. 3 except that the third insulating layer (530) is omitted, so redundant descriptions will be omitted.

[0165] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art will understand that the present invention may be implemented in other specific forms without changing the technical concept or essential features thereof. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. Explanation of the symbols

[0166] 10: Display device 710: First contact electrode 210: First electrode 720: Second contact electrode 220: Second electrode 400: 1st Bank 600: 2nd Bank 410: 1st Sub-bank 420: 2nd Sub-bank

Claims

Claim 1 A substrate; a first electrode and a second electrode spaced apart from each other along a direction parallel to one surface of the substrate on one surface of the substrate; an insulating layer located on the first electrode and the second electrode; and a light-emitting element located on the insulating layer and extending in a first direction, wherein one end in the first direction overlaps with the first electrode and the other end in the first direction overlaps with the second electrode, wherein the first diameter of one end of the light-emitting element is different from the second diameter of the other end of the light-emitting element, and the light-emitting element comprises a first semiconductor layer, a second semiconductor layer spaced apart from the first semiconductor layer, and an active layer disposed between the first semiconductor layer and the second semiconductor layer, wherein the active layer is located adjacent to the end side having the larger diameter between the first diameter and the second diameter, and the light-emitting element further comprises an insulating film surrounding the side of the first semiconductor layer, the second semiconductor layer, and the active layer, and the light-emitting element is spaced apart from the first electrode and the second electrode with the insulating layer in between, and A display device comprising a first insulating layer disposed on a light-emitting element such that the active layer completely overlaps the second electrode along the thickness direction of the substrate, which is perpendicular to one surface of the substrate, and the first insulating layer is disposed on the light-emitting element to expose one end and the other end of the light-emitting element, wherein the active layer does not overlap the first insulating layer along the thickness direction of the substrate. Claim 2 In claim 1, the second diameter is a display device larger than the first diameter. Claim 3 delete Claim 4 delete Claim 5 A display device according to claim 2, wherein the second semiconductor layer is disposed on one end side of the light-emitting element and the first semiconductor layer is disposed on the other end side of the light-emitting element. Claim 6 A display device according to claim 5, wherein the thickness of the first semiconductor layer in the first direction is smaller than the thickness of the second semiconductor layer in the first direction. Claim 7 In claim 5, the light-emitting element is a display device that emits red light having a central wavelength band in the range of 600 nm to 750 nm. Claim 8 In claim 5, the first semiconductor layer and the second semiconductor layer each comprise phosphorus (P) in a display device. Claim 9 In claim 5, a display device in which the minimum diameter of the first semiconductor layer is larger than the maximum diameter of the second semiconductor layer. Claim 10 In claim 9, a display device in which the diameter of the active layer decreases as it goes from the first semiconductor layer to the second semiconductor layer. Claim 11 A display device according to claim 2, wherein the light-emitting element comprises a first surface which is one end surface, a second surface which is the other end surface, and a third surface connecting the first surface and the second surface, and the first distance in the first direction between one surface of the active layer facing the first surface and the first surface is longer than the second distance in the first direction between the other surface of the active layer facing the second surface and the second surface. Claim 12 A display device according to claim 11, wherein the cross-sectional shape of the light-emitting element cut along the first direction is a trapezoidal shape. Claim 13 In claim 1, the display device wherein the diameter of the light-emitting element decreases along the first direction. Claim 14 A display device according to claim 1, wherein the first semiconductor layer, the active layer, and the second semiconductor layer are sequentially arranged along the first direction. Claim 15 delete Claim 16 A display device according to claim 1, wherein the active layer comprises a first region that overlaps the first insulating layer and the substrate in the thickness direction and a second region that does not overlap, and the thickness of the first region in the first direction is smaller than the thickness of the second region in the first direction. Claim 17 delete Claim 18 A display device according to claim 1, further comprising: a first contact electrode in contact with one end of the light-emitting element and the first electrode; and a second contact electrode in contact with the other end of the light-emitting element and the second electrode, wherein the first contact electrode and the second contact electrode are electrically insulated from each other. Claim 19 In claim 1, one end and the other end of the light-emitting element are a display device tilted with respect to one surface of the substrate. Claim 20 In claim 19, a display device in which the inclined directions of one end and the other end of the light-emitting element with respect to one surface of the substrate are the same.

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