Light-emitting element, and display device having the same

Abstract

To provide a light-emitting element.SOLUTION: A light-emitting element includes: a first light-emitting cell, a second light-emitting cell, and a third light-emitting cell each including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a pad electrically connected with the first to third light-emitting cells so as to independently drive the first to third light-emitting cells; a second wavelength converter that converts a wavelength of light emitted by the second light-emitting cell; and a third wavelength converter that converts a wavelength of light emitted by the third light-emitting cell. The third wavelength converter converts a wavelength of light into a longer wavelength than that converted by the second wavelength converter. The second light-emitting cell has an area larger than that of the first light-emitting cell, and the third light-emitting cell has an area larger than that of the second light-emitting cell.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a light-emitting element and a display device having the same. [Background technology]

[0002] Among light emitting devices, light emitting diodes are inorganic light sources and are used in a variety of fields such as display devices, vehicle lamps, general lighting, etc. Light emitting diodes have the advantages of long life, low power consumption, and fast response speed, and are rapidly replacing existing light sources.

[0003] Meanwhile, conventional light emitting diodes have been mainly used as backlight sources in display devices, but recently, micro LEDs have been developed as a next-generation display device that directly displays images using light emitting diodes.

[0004] A display device generally uses a mixture of blue, green, and red colors to realize various colors. Each pixel of the display device has blue, green, and red sub-pixels, and the color of a particular pixel is determined by the colors of these sub-pixels, and an image is realized by a combination of these pixels.

[0005] In the case of a micro LED display device, a micro LED is arranged corresponding to each sub-pixel, and therefore a large number of micro LEDs must be arranged on one substrate. However, micro LEDs are very small, with sizes of less than 200 micrometers, even less than 100 micrometers, and such small sizes cause various problems. In particular, it is difficult to handle small light emitting diodes, and it is not easy to mount light emitting diodes on a panel, and it is also difficult to replace defective LEDs among the mounted micro LEDs with good LEDs.

[0006] Meanwhile, light emitting diodes generally emit ultraviolet or blue light, and can realize green and red light in combination with phosphors. In addition, color filters are used for each subpixel to improve the purity of each color, but the color filters also have differences in filter efficiency. Therefore, even if the same light emitting diode is operated to emit light of the same intensity, differences in light intensity occur among the blue, green, and red subpixels. In order to overcome such differences, the operating current density of each light emitting diode can be changed, but the light emitting efficiency of the light emitting diode decreases according to the change in current density. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a light emitting diode that is easy to mount and replace, and a display device having the same.

[0008] Another object of the present invention is to provide a light emitting diode capable of operating a light emitting diode of each sub-pixel with optimal light emitting efficiency, and a display device having the same.

[0009] Another problem to be solved by the present invention is to provide a display device having high color purity and color reproducibility. [Means for solving the problem]

[0010] A light emitting device according to an embodiment of the present invention includes a first light emitting cell, a second light emitting cell, and a third light emitting cell, each including a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer; pads electrically connected to the first light emitting cell to independently drive the first light emitting cell, a second wavelength converter for converting a wavelength of light emitted from the second light emitting cell, and a third wavelength converter for converting a wavelength of light emitted from the third light emitting cell, wherein the third wavelength converter converts a wavelength of light to a longer wavelength than the second wavelength converter, and the second light emitting cell has a larger area than the first light emitting cell, and the third light emitting cell has a larger area than the second light emitting cell.

[0011] In one embodiment of the present invention, the first to third light emitting cells may emit blue light, the second wavelength converter may convert the blue light to green light, and the third wavelength converter may convert the blue light to red light.

[0012] In an embodiment of the present invention, area ratios of the second light emitting cells and the third light emitting cells to the first light emitting cells may be inversely proportional to the light conversion efficiency of the second wavelength converter and the light conversion efficiency of the third wavelength converter, respectively.

[0013] In one embodiment of the present invention, the light emitting device further includes a first wavelength converter that converts a wavelength of light emitted from the first light emitting cell into light of a first wavelength, and the first wavelength converter converts the wavelength of light to a shorter wavelength than that of the second wavelength converter, and the first to third light emitting cells can emit ultraviolet light.

[0014] In one embodiment of the present invention, the first wavelength converter can convert ultraviolet light to blue light, the second wavelength converter can convert the ultraviolet light to green light, and the third wavelength converter can convert the ultraviolet light to red light.

[0015] In an embodiment of the present invention, the area ratios of the second light emitting cells and the third light emitting cells to the first light emitting cells may be inversely proportional to the optical conversion efficiency ratio of the second wavelength converter to the first wavelength converter and the optical conversion efficiency ratio of the third wavelength converter to the first wavelength converter, respectively.

[0016] In one embodiment of the present invention, the light-emitting element may further include a first color filter disposed on the first wavelength converter, a second color filter disposed on the second wavelength converter, and a third color filter disposed on the third wavelength converter.

[0017] In an embodiment of the present invention, the light emitting device may further include a second color filter disposed on the second wavelength converter, and a third color filter disposed on the third wavelength converter.

[0018] In an embodiment of the present invention, the light emitting device may further include a substrate on which the first, second and third light emitting cells are disposed.

[0019] In one embodiment of the present invention, the light shielding device may include a partition wall provided between each of the first light emitting cells to the third light emitting cells to block the light, the height of the first light emitting cells to the third light emitting cells may be lower than the height of the partition wall, and a distance between the partition wall and the first light emitting cells to the third light emitting cells may be 10 μm to 20 μm.

[0020] In an embodiment of the present invention, the barrier ribs provided between the first light emitting cell, the second light emitting cell, and the third light emitting cell may be connected to each other.

[0021] In one embodiment of the invention, the width of the partitions may increase with distance from the substrate.

[0022] In an embodiment of the present invention, a ratio of an area occupied by the partition wall to a planar area of ​​the substrate may be 0.5 to 0.99.

[0023] In one embodiment of the present invention, the height of the partition wall may be 15 μm to 115 μm.

[0024] In one embodiment of the present invention, the first light emitting cell may emit red light, the second light emitting cell may emit green light, and the third light emitting cell may emit blue light, and a distance between the first light emitting cell and the second light emitting cell may be the same as a distance between the first light emitting cell and the third light emitting cell. In one embodiment of the present invention, a distance between the first light emitting cell and the second light emitting cell may be different from a distance between the second light emitting cell and the third light emitting cell.

[0025] In one embodiment of the present invention, the first light emitting cell to the third light emitting cell are provided within one light emitting element, and a distance between the first light emitting cell to the third light emitting cell provided in one pixel may be shorter than a distance between the first light emitting cell to the third light emitting cell provided in the one pixel and the first light emitting cell to the third light emitting cell provided in a pixel adjacent to the one pixel.

[0026] In an embodiment of the present invention, the first light emitting cell, the second light emitting cell, and the third light emitting cell may be arranged in a triangular shape, or the first light emitting cell, the second light emitting cell, and the third light emitting cell may be arranged in a linear shape.

[0027] In an embodiment of the present invention, the first to third light emitting cells may share a first conductive type semiconductor layer.

[0028] In an embodiment of the present invention, the light emitting device may further include an extension portion extending from the pad electrically connected to the shared first conductive type semiconductor layer among the pads.

[0029] In one embodiment of the present invention, the second wavelength converter and the third wavelength converter may be located within the same film.

[0030] In one embodiment of the present invention, the second wavelength converter and the third wavelength converter may be located in a laminate film, and the second wavelength converter and the third wavelength converter may be located in different layers from each other.

[0031] In one embodiment of the present invention, a light emitting device includes a substrate, a first light emitting cell, a second light emitting cell, and a third light emitting cell provided on the substrate and emitting red light, green light, and blue light, and a partition wall provided between each of the first light emitting cells to the third light emitting cells to block the light, wherein a height of the first light emitting cells to the third light emitting cells is lower than a height of the partition wall, and a distance between the partition wall and the first light emitting cells to the third light emitting cells may be 5 μm or less.

[0032] The light-emitting element of the present invention can be adopted in a display device, the display device including a circuit board and a plurality of pixels arranged on the circuit board, each of the plurality of pixels being a light-emitting element according to the above embodiment. Effect of the Invention

[0033] According to an embodiment of the present invention, since sub-pixels including first to third light emitting cells and emitting light of different colors can be arranged in one light emitting diode, it is possible to provide a light emitting diode that is easy to mount and replace. Furthermore, by making the areas of the first to third light emitting cells different, it is possible to operate the light emitting cells of each sub-pixel with optimal light emitting efficiency.

[0034] In addition, according to one embodiment of the present invention, a display device with high color purity and color reproducibility can be provided. [Brief description of the drawings]

[0035] [Figure 1] 1 is a plan view of a display device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an enlarged plan view showing a portion P1 of FIG. [Diagram 3] 1 is a structural diagram showing a display device according to an embodiment of the present invention; [Figure 4a] FIG. 2 is a circuit diagram showing a sub-pixel, and is a circuit diagram showing an example of a pixel constituting a passive display device. [Figure 4b]FIG. 2 is a circuit diagram showing a sub-pixel, which is an example of a pixel constituting an active type display device. [Figure 5a] FIG. 3 is a plan view showing one pixel in the display device shown in FIG. 2. [Figure 5b] FIG. 5b is a cross-sectional view taken along line II' in FIG. 5a. [Figure 6] 1 is a cross-sectional view showing a light emitting cell according to an embodiment of the present invention; [Figure 7a] FIG. 2 is a plan view showing a pixel according to an embodiment of the present invention. [Figure 7b] FIG. 2 is a plan view showing a pixel according to an embodiment of the present invention. [Figure 8a] 1 is a cross-sectional view showing a display device according to an embodiment of the present invention; [Figure 8b] 1 is a cross-sectional view showing a display device according to an embodiment of the present invention; [Figure 8c] 1 is a cross-sectional view showing a display device according to an embodiment of the present invention; [Figure 8d] 1 is a cross-sectional view showing a display device according to an embodiment of the present invention; [Figure 9] 1 is a schematic plan view illustrating a light emitting device according to an embodiment of the present invention; [Figure 10] FIG. 10 is a schematic cross-sectional view taken along cut line AA in FIG. 9. [Figure 11] FIG. 11 is a schematic plan view illustrating a light emitting device according to another embodiment of the present invention. [Figure 12] FIG. 12 is a schematic cross-sectional view taken along cut line BB in FIG. 11. [Figure 13] FIG. 11 is a schematic plan view illustrating a pixel according to another embodiment of the present invention. [Figure 14] FIG. 14 is a schematic cross-sectional view taken along cut line CC in FIG. 13. [Figure 15] FIG. 14 is a schematic enlarged cross-sectional view taken along cut line DD in FIG. 13. [Figure 16] FIG. 11 is a schematic plan view illustrating a pixel according to another embodiment of the present invention. [Figure 17] FIG. 17 is a schematic cross-sectional view taken along cut line EE of FIG. 16. [Figure 18] FIG. 11 is a schematic cross-sectional view illustrating a pixel according to another embodiment of the present invention. [Figure 19a] FIG. 2 is a cross-sectional view illustrating a film including a wavelength converter. [Figure 19b] FIG. 2 is a cross-sectional view illustrating a film including a wavelength converter. [Figure 20] 1 is a schematic plan view illustrating a display device according to an embodiment of the present invention; [Figure 21] 1 is a perspective view showing a display device according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to fully convey the concept of the present invention to those skilled in the art to which the present invention pertains. Therefore, the present invention is not limited to the embodiments described below, and may be embodied in other forms. In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. In addition, when a component is described as being "on" or "above" another component, this includes not only the case where each part is "directly on" or "directly above" the other part, but also the case where another component is interposed between each component and the other component. The same reference numerals refer to the same components throughout the specification.

[0037] The present invention relates to a light emitting device that emits light, which can be used as a light source in various devices, and in particular, can be adopted in a display device to function as a pixel. Hereinafter, a display device will be described first, and an embodiment of a light emitting device as a pixel adopted in the display device will be described in sequence with reference to the drawings. However, the light emitting device according to an embodiment of the present invention is not limited to use in a display device, and may be adopted as a light source in other devices as necessary.

[0038] FIG. 1 is a plan view of a display device according to one embodiment of the present invention, and FIG. 2 is an enlarged plan view showing a P1 portion of FIG.

[0039] 1 and 2, a display device 10 according to an embodiment of the present invention displays any visual information, such as text, video, photos, 2D or 3D images, and the like.

[0040] The display device 10 may be provided in various shapes, for example, a closed polygon having straight sides such as a rectangle, a circle having curved sides such as an ellipse, a semicircle having straight and curved sides such as a semi-ellipse, etc. In one embodiment of the present invention, the display device is illustrated as being provided in a rectangular shape.

[0041] The display device 10 has a number of pixels 100 for displaying an image. Each pixel 100 is the smallest unit for displaying an image. Each pixel 100 can emit white light and / or colored light. Each pixel 100 can include one sub-pixel that emits one color, or can include multiple sub-pixels that combine different colors to emit white light and / or colored light.

[0042] Since each pixel 100 can be realized by a light emitting device, the term "light emitting device" hereinafter may be used to mean substantially the same thing as "pixel" in consideration of the fact that the term is used to realize one pixel.

[0043] In this embodiment, each pixel 100 may include a plurality of light emitting cells, or a sub-pixel implemented with a plurality of light emitting cells and other components for converting light from the light emitting cells. The plurality of light emitting cells may be implemented, for example, as first to third light emitting cells 111P, 113P, and 115P.

[0044] In an embodiment of the present invention, each pixel may include a light emitting cell G emitting green light, a light emitting cell R emitting red light, and a light emitting cell B emitting blue light, and the first to third light emitting cells 111P, 113P, and 115P may correspond to the light emitting cell G emitting green light, the light emitting cell R emitting red light, and the light emitting cell B emitting blue light. However, the light emitting cells that each pixel 100 may include are not limited thereto. For example, each pixel 100 may include light emitting cells that emit cyan, magenta, yellow light, etc., and each pixel may include a green light emitting cell G emitting green light, a red light emitting cell R emitting red light, and a blue light emitting cell B emitting blue light.

[0045] The pixels 100 and / or the light emitting cells 111P, 113P, 115P are arranged in a matrix. Here, the fact that the pixels 100 and / or the light emitting cells 111P, 113P, 115P are arranged in a matrix does not mean that the pixels 100 and / or the light emitting cells 111P, 113P, 115P are arranged exactly in a line along rows or columns, but may be arranged generally along rows or columns, but the detailed positions may be changed, such as being arranged in a zigzag shape.

[0046] FIG. 3 is a structural diagram showing a display device according to an embodiment of the present invention.

[0047] 3, the display device 10 according to an embodiment of the present invention includes a timing controller 350, a scan driver 310, a data driver 330, a wiring unit, and a pixel. Here, when a pixel includes a plurality of light emitting cells 111P, 113P, 115P, each of the light emitting cells 111P, 113P, 115P is individually connected to the scan driver 310, the data driver 330, etc. through the wiring unit.

[0048] The timing controller 350 receives various control signals and image data required to drive the display device from the outside (for example, a system that transmits image data). The timing controller 350 rearranges the received image data and transmits it to the data driver 330. The timing controller 350 also generates scan control signals and data control signals required to drive the scan driver 310 and the data driver 330, and transmits the generated scan control signals and data control signals to the scan driver 310 and the data driver 330, respectively.

[0049] The scan driver 310 receives a scan control signal from the timing controller 350 and generates a scan signal in response thereto.

[0050] The data driver 330 receives a data control signal and image data from the timing controller 350 and generates a data signal in response thereto.

[0051] The wiring unit includes a number of signal wirings. Specifically, the wiring unit includes a first wiring 130 connecting the scan driver 310 and the light emitting cells 111P, 113P, and 115P, and a second wiring 120 connecting the data driver 330 and the light emitting cells 111P, 113P, and 115P. In an embodiment of the present invention, the first wiring 130 is a scan wiring and the second wiring 120 is a data wiring, so that the first wiring will be described as a scan wiring and the second wiring as a data wiring hereinafter. In addition, the wiring unit further includes wirings connecting the timing controller 350 and the scan driver 310, the timing controller 350 and the data driver 330, or other components and transmitting corresponding signals.

[0052] The scan lines 130 provide scan signals generated by the scan driver 310 to the light emitting cells 111P, 113P, and 115P. The data signals generated by the data driver 330 are output to the data lines 120. The data signals output to the data lines 120 are input to the light emitting cells 111P, 113P, and 115P of a horizontal pixel line selected by the scan signal.

[0053] The light emitting cells 111P, 113P, and 115P are connected to the scan lines 130 and the data lines 120. When a scan signal is supplied from the scan lines 130, the light emitting cells 111P, 113P, and 115P selectively emit light in response to a data signal input from the data lines 120. For example, during each frame period, the light emitting cells 111P, 113P, and 115P emit light with a luminance corresponding to a received data signal. The light emitting cells 111P, 113P, and 115P to which a data signal corresponding to black luminance is supplied do not emit light during the corresponding frame period, thereby displaying black.

[0054] In an embodiment of the present invention, the sub-pixels, i.e., the light emitting cells, may be driven in a passive or active manner. When the display device is driven in an active manner, the display device may be driven by being further supplied with first and second sub-pixel power sources in addition to the scan signals and data signals.

[0055] 4a is a circuit diagram showing one sub-pixel, which is an example of a pixel constituting a passive display device, where the sub-pixel is one of the sub-pixels, for example, one of the red sub-pixel, green sub-pixel, and blue sub-pixel, and in this embodiment, represents a first light emitting cell 111P.

[0056] 4a, the first light emitting cell 111P includes a light source LD connected between the scan line 130 and the data line 120. The light source LD is a light emitting diode having first and second terminals. The first and second terminals are respectively connected to a first electrode (e.g., an anode) and a second electrode (e.g., a cathode) in the light emitting cell. Here, the first terminal may be connected to the scan line 130 and the second terminal may be connected to the data line 120, or vice versa.

[0057] When a voltage equal to or greater than a threshold voltage is applied between the first and second electrodes, the light source LD emits light with a brightness corresponding to the magnitude of the applied voltage. That is, the light emission of the first light source 111P can be controlled by adjusting the voltage of the scan signal applied to the scan line 130 and / or the data signal applied to the data line 120.

[0058] In the embodiment of the present invention, a case where only one light source LD is connected between the scan line 130 and the data line 120 is illustrated, but the present invention is not limited to this. A plurality of light sources LD may be connected between the scan line 130 and the data line 120, and in this case, the light sources LD may be connected in parallel or in series.

[0059] 4b is a circuit diagram showing a first light emitting cell 111P, which is an example of a sub-pixel constituting an active-type display device. When the display device is an active type, the first light emitting cell 111P may be driven by receiving first and second sub-pixel power sources ELVDD and ELVSS in addition to the scan signals and data signals.

[0060] Referring to FIG. 4b, the first light emitting cell 111P includes one or more light sources LD and a transistor unit TFT connected thereto.

[0061] A first electrode of the light source LD is connected to the first sub-pixel power supply ELVDD via the transistor unit TFT, and a second electrode of the light source LD is connected to the second sub-pixel power supply ELVSS. The first sub-pixel power supply ELVDD and the second sub-pixel power supply ELVSS may have different potentials. For example, the second sub-pixel power supply ELVSS may have a potential lower than the potential of the first sub-pixel power supply ELVDD by at least a threshold voltage of the light emitting cell. Each of these light sources emits light with a brightness corresponding to a driving current controlled by the transistor unit TFT.

[0062] According to an embodiment of the present invention, the transistor unit TFT includes first and second transistors M1 and M2 and a storage capacitor Cst, but the structure of the transistor unit TFT is not limited to the embodiment shown in FIG.

[0063] A source electrode of a first transistor M1 (switching transistor) is connected to the data line 120, and a drain electrode of the first transistor is connected to the first node N1. A gate electrode of the first transistor is connected to the scan line 130. When a scan signal having a voltage capable of turning on the first transistor M1 is supplied from the scan line 130, the first transistor is turned on to electrically connect the data line 120 and the first node N1. At this time, a data signal of a corresponding frame is supplied to the data line 120, and the data signal is transferred to the first node N1 accordingly. The data signal transferred to the first node N1 is charged in the storage capacitor Cst.

[0064] The second transistor M2 (driving transistor) has a source electrode connected to the first sub-pixel power supply ELVDD, a drain electrode connected to the first electrode of the light emitting cell, and a gate electrode connected to the first node N1, and controls the amount of driving current supplied to the light emitting cell in response to the voltage of the first node N1.

[0065] One electrode of the storage capacitor Cst is connected to the first sub-pixel power supply ELVDD and the other electrode is connected to the first node N1, and the storage capacitor Cst charges a voltage corresponding to the data signal supplied to the first node N1 and maintains the charged voltage until the data signal of the next frame is supplied.

[0066] For convenience, Fig. 4b illustrates a transistor portion TFT including two transistors. However, the present invention is not limited thereto, and the structure of the transistor portion TFT may be modified in various ways. For example, the transistor portion may include more transistors, capacitors, etc. Also, in this embodiment, specific structures of the first and second transistors, storage capacitors, and wiring are not illustrated, but the first and second transistors, storage capacitors, and wiring may be provided in various forms within the limits of implementing the circuit according to the embodiment of the present invention.

[0067] FIG. 5a is a plan view showing one pixel in the display device shown in FIG. 2, and FIG. 5b is a cross-sectional view taken along line II' of FIG. 5a.

[0068] According to an embodiment of the present invention, a substrate 210 is provided, and a first light emitting cell 111P, a second light emitting cell 113P, and a third light emitting cell 115P are provided on the substrate 210 and can emit red light, green light, and blue light.

[0069] A light-shielding barrier rib 220 is provided between each of the first to third light emitting cells 111P, 113P, and 115P. The heights of the first to third light emitting cells 111P, 113P, and 115P are lower than the height of the barrier rib 220.

[0070] Further, the distance between the barrier rib 220 and the first to third light emitting cells 111P, 113P, and 115P is 10 μm to 20 μm.

[0071] In the following description, the first to third light emitting cells 111P, 113P, and 115P may be commonly referred to as 'light emitting cells' when content commonly applies to all the light emitting cells.

[0072] Furthermore, a bundle of the first to third light emitting cells 111P, 113P, and 115P, which is the minimum unit capable of producing white light, is called a 'pixel' or a 'light emitting element'.

[0073] Hereinafter, each component included in the display device will be described in more detail.

[0074] The substrate 210 includes a wiring portion for providing power and signals to the pixels 100 .

[0075] Although not shown, a wiring section including scan lines and data lines connected to the pixels 100 and / or a transistor section may be formed on the substrate 210 .

[0076] In one embodiment of the present invention, the substrate 210 is a printed circuit board. When the substrate 210 is provided as a printed circuit board, the printed circuit board may be provided with wiring parts connected to the pixels 100, and may also be provided with circuits such as a timing control part, a scan driving part, and a data driving part.

[0077] The printed circuit board is a double-sided printed circuit board with wiring parts formed on both sides, and in this case, the wiring parts may include pad parts 235a, 235b provided on the upper surface of the printed circuit board to be electrically connected to the pixel 100, and connection parts 235ba, 235bb penetrating the upper and lower surfaces of the printed circuit board. Electrodes 231, 232 or wiring etc. may be mounted on the lower surface of the printed circuit board, and the wiring of the pixel 100 is connected to the electrodes 231, 232 and wiring etc. on the lower surface of the printed circuit board through the pad parts 235a, 235b and connection parts 235ba, 235bb etc.

[0078] However, the substrate 210 may be provided as something other than a printed circuit board on which the pixel 100 can be mounted. For example, the substrate 210 may be an insulating substrate such as glass, quartz, plastic, etc. on which a wiring portion is formed. In this case, circuits such as a timing control unit, a scan driver, a data driver, etc. may be directly formed on the insulating substrate, or may be provided on a separate printed circuit board, etc., and then connected to the wiring portion of the insulating substrate.

[0079] The substrate 210 is made of a hard material, but is not limited thereto, and may be made of a flexible material. When the display device according to an embodiment of the present invention is embodied as a curved or bendable display device, the substrate 210 is advantageously made of a flexible material. In an embodiment of the present invention, when the substrate 210 is made of a material such as glass, quartz, etc., it has a relatively high heat resistance compared to an organic polymer substrate, and therefore has an advantage that various laminations can be performed on the upper surface. When the substrate 210 is made of a transparent material such as glass, quartz, etc., it is advantageous for manufacturing a front or rear light emitting display device. When the substrate 210 is made of an organic polymer, an organic-inorganic composite material, etc., it has a relatively high flexibility, and therefore is advantageous for manufacturing a curved display device.

[0080] At least one pixel 100 is mounted on the substrate 210 via a conductive adhesive layer. In the display device, the pixel 100 is mounted in a sub-pixel region of the substrate 210.

[0081] According to an embodiment of the present invention, the pixel 100 includes a first light emitting cell 111P, a second light emitting cell 113P, and a third light emitting cell 115P. The light emitting cells 111P, 113P, and 115P are provided on a substrate 210 in a planar spaced apart shape.

[0082] The first to third light emitting cells 111P, 113P, and 115P may emit light of different wavelength bands. That is, if the lights emitted by the first to third light emitting cells 111P, 113P, and 115P are respectively referred to as first to third lights, the first to third lights may have different wavelength bands. In this embodiment, as described above, the first to third lights may have green, red, and blue wavelength bands, respectively, and in this case, the first to third light emitting cells 111, 113, and 115 are embodied as green, red, and blue light emitting diodes.

[0083] However, according to an embodiment, some or all of the first to third light emitting cells 111P, 113P, and 115P may emit light of the same wavelength. For example, the first light emitting cell 111P may emit light of a first wavelength, and the second light emitting cell 113P and the third light emitting cell 115P may emit light of a second wavelength that is different from the first wavelength or the same as each other. In this case, a wavelength converter 250 may be provided on the second light emitting cell or the third light emitting cell 113P, 115P. The wavelength converter 250 may convert the wavelength of the light emitted from the light emitting cell. For example, the ultraviolet or blue wavelength band light emitted from the second light emitting cell 113P may be converted to a red wavelength band light while passing through the wavelength converter 250. Therefore, even if some or all of the first to third light emitting cells 111P, 113P, and 115P emit light of the same wavelength, a user can visually recognize the light as if different wavelengths were emitted from each of the light emitting cells 111P, 113P, and 115P.

[0084] Each of the light emitting cells 111P, 113P, and 115P is mounted on the pad parts 235a and 235b provided on the upper surface of the substrate 210. At this time, as described above, a conductive adhesive layer may be provided between the light emitting cells 111P, 113P, and 115P and the pad parts 235a and 235b to ensure a stable electrical connection. The conductive adhesive layer may be made of a conductive paste such as solder paste or silver paste, or a conductive resin.

[0085] The pad parts 235a and 235b are connected to the electrodes 231 and 232 provided on the rear surface of the substrate 210 by connection parts 235ba and 235bb that penetrate the substrate 210. At this time, the electrodes 231 and 232 may include a common electrode 231 and a subpixel electrode 232. The first to third light emitting cells 111P, 113P, and 115P provided in the pixel 100 may be connected to one common electrode 231. Furthermore, a plurality of subpixel electrodes 232 may be provided, and each subpixel electrode 232 may correspond one-to-one to the first to third light emitting cells 111P, 113P, and 115P.

[0086] According to an embodiment of the present invention, the light emitting cells 111P, 113P, and 115P provided in one pixel 100 are connected to the same common electrode 231, thereby simplifying the wiring structure and improving the efficiency of the manufacturing process of the display device. When the light emitting cells 111P, 113P, and 115P are connected to one common electrode 231, the size of the common electrode 231 is relatively larger than that of the sub-pixel electrode 232.

[0087] The common electrode 231 and the sub-pixel electrode 232 may be connected to data lines and scan lines of the display device, so that scan signals and data signals are transmitted to the light emitting cells 111P, 113P, and 115P through the common electrode 231 and the sub-pixel electrode 232.

[0088] The common electrode 231 and the sub-pixel electrode 232 are different types of electrodes, for example, if the common electrode 231 is a p-type electrode, the sub-pixel electrode 232 is an n-type electrode, and vice versa.

[0089] The size of the common electrode 231 and the sub-pixel electrode 232 may be larger than the size of the first terminal and the second terminal of the light emitting cell.

[0090] The barrier ribs 220 are provided on the substrate 210. At this time, the barrier ribs 220 are provided between the first to third light emitting cells 111P, 113P, and 115P.

[0091] The barrier ribs 220 may be connected to each other and provided as an integral unit, or may be provided separately from each other. For example, the barrier rib 220 provided between the first light emitting cell 111P and the second light emitting cell 113P and the barrier rib provided between the second light emitting cell 113P and the third light emitting cell 115P may be connected to each other or may be separated from each other.

[0092] Hereinafter, a case where the barrier ribs 220 provided between the light emitting cells 111P, 113P, and 115P are connected to each other and provided as one unit will be described as an example.

[0093] The partition 220 provided integrally includes a plurality of openings 221, 222, and 223 in each pixel 100. The partition 220 is provided such that the light emitting cells 111P, 113P, and 115P are provided within the openings 221, 222, and 223.

[0094] The partition 220 is an insulating film made of a non-conductive material and is a layer that does not transmit light. In an embodiment of the present invention, the partition 220 may be made of a light absorbing material. The partition 220 may be provided in black and may be made of, for example, a light blocking material used in a display device.

[0095] According to an embodiment, the barrier ribs 220 may be formed from a composition in which a photosensitive solder resist (PSR) and a light absorbing material are mixed. By using a composition in which a photosensitive solder resist and a light absorbing material are mixed, a process for forming the barrier ribs 220 can be simplified. Specifically, the composition is applied at room temperature and photo-cured, so that the barrier ribs 220 can be formed without harsh process conditions.

[0096] Various materials can be used as the photosensitive solder resist PSR for forming the barrier rib 220. For example, the photosensitive solder resist can include a photosensitive organic polymer. The photosensitive organic polymer is any one selected from polyethylene, polypropylene, polyvinyl chloride, polystyrene, ABS resin (Acrylonitrile-Butadiene-Styrene resin), methacrylate resin, polyamide, polycarbonate, polyacetyl, polyethylene terephthalate, modified PPO resin (Modified Polyphenylene Oxide), polybutylene terephthalate, polyurethane, phenolic resin, urea resin, melamine resin, and combinations thereof.

[0097] Furthermore, in order to facilitate the photo-curing reaction of the photosensitive solder resist PSR, a photosensitive curing agent may be further included in the composition for forming the partition wall 220. However, the partition wall 220 may be formed using various materials other than the above-mentioned materials.

[0098] In one embodiment of the present invention, the composition for forming the partition wall 220 is a mixture of polydimethylsiloxane (PDMS) and carbon particles.

[0099] Since the partition 220 contains a light absorbing material, it can absorb a part of the light emitted from the light emitting cells 111P, 113P, and 115P. Specifically, a part of the light emitted from the light emitting cells 111P, 113P, and 115P and traveling toward the adjacent light emitting cells 111P, 113P, and 115P is absorbed by the partition 220. Therefore, it is possible to prevent unnecessary color mixing of the lights emitted from different light emitting cells 111P, 113P, and 115P. Furthermore, since unnecessary color mixing of the lights is prevented, the color combination of the lights viewed from the display device is the same even when viewed from any direction.

[0100] However, the prevention of unnecessary color mixing of light by the partition 220 does not mean that the mixing of a plurality of lights emitted from one pixel 100 is completely blocked. For example, when one pixel 100 includes a plurality of light emitting cells 111P, 113P, and 115P and each light emitting cell emits red light, blue light, and green light, the red light, blue light, and green light are mixed and perceived as white light by a user. The partition 220 prevents light from being mixed with light from an adjacent pixel unnecessarily, and the white light is perceived as a different color when the display device is viewed from a direction other than perpendicular to the display device.

[0101] In order to prevent such unnecessary color mixing, the height of the barrier rib 220 is higher than the height of the light emitting cells 111P, 113P, and 115P. For example, when the barrier rib 220 has a second height H2 and any one of the first to third light emitting cells 111P, 113P, and 115P has a first height H1, the second height H2 is higher than the first height H1.

[0102] In this case, the first height H1 is the distance from the upper surface of the substrate 210 to the upper surfaces of the light emitting cells 111P, 113P, and 115P. In the case where the upper surfaces of the light emitting cells 111P, 113P, and 115P are provided with unevenness so that the upper surfaces of the light emitting cells are curved, the first height H1 is the distance from the upper surface of the substrate 210 to the edge of the unevenness on the upper surfaces of the light emitting cells 111P, 113P, and 115P.

[0103] The second height H2 means the distance from the contact surface between the substrate 210 and the partition wall 220 to the upper surface of the partition wall 220. Furthermore, when the thickness of the partition wall 220 varies depending on the position on the plane, the second height H2 means the average distance from the contact surface between the substrate 210 and the partition wall 220 to the upper surface of the partition wall 220.

[0104] The second height H2 is about 15 μm to about 115 μm. The above-mentioned numerical range is the height of the barrier rib 220 for preventing unnecessary color mixing of the lights emitted from the first to third light emitting cells 111P, 113P, and 115P. Furthermore, when the second height H2 exceeds about 115 μm, the amount of light emitted from the light emitting cells 111P, 113P, and 115P may be excessively reduced or the thickness of the entire display device may be excessively large. Furthermore, when the second height H2 is less than about 15 μm, unnecessary color mixing may occur between the lights emitted from the light emitting cells 111P, 113P, and 115P. When different light emitting cells 111P, 113P, and 115P are provided in the pixel 100, the first height H1 may be different for each of the light emitting cells 111P, 113P, and 115P. However, even in this case, the second height H2 is higher than the first height H1, so that the second height H2 is higher than the first height H1 of any of the light emitting cells 111P, 113P, and 115P.

[0105] According to one embodiment of the invention, the difference between the second height H2 and the first height H1 is greater than 0 and is equal to or less than about 100 μm. If the difference between the second height H2 and the first height H1 is greater than about 100 μm, the mixture of light emitted from one pixel 100 may be blocked, making it difficult to realize white light.

[0106] When the pixel 100 is a flip chip, the first height H1 is about 10 μm to about 20 μm, so that the thickness of the barrier rib 220 or the second height H2 is relatively small, and the thickness of the entire display device can be reduced.

[0107] The widths of the openings 221, 222, 223 through which the light emitting cells 111P, 113P, 115P are provided may vary depending on the light emitting cells 111P, 113P, 115P. For example, the sizes of the openings 221, 222, 223 may vary depending on the sizes of the light emitting cells 111P, 113P, 115P.

[0108] The width of the openings 221, 222, and 223 is greater than that of the light emitting cells 111P, 113P, and 115P. The light emitting cells 111P, 113P, and 115P are arranged so as not to contact the sidewalls of the partition walls 220 that form the openings 221, 222, and 223 with the light emitting cells 111P, 113P, and 115P.

[0109] The distance between the light emitting cells 111P, 113P, 115P and the sidewalls of the openings 221, 222, 223 is about 10 μm to about 20 μm. This range of values ​​allows the partitions 220 to prevent unnecessary color mixing of the lights emitted from the light emitting cells 111P, 113P, 115P while reducing the ratio of the area opened by the openings 221, 222, 223. In an embodiment of the present invention, the area occupied by the partitions 220 in the planar area of ​​the display device is about 50% to about 99% of the entire area. As the area occupied by the partitions 220 becomes relatively larger, the contrast ratio of the display device can be improved.

[0110] According to an embodiment of the invention, the width of the light emitting cells 111P, 113P, 115P is 200 μm or less. For example, when the light emitting cells 111P, 113P, 115P have a rectangular shape, the length of one side of the rectangle is about 200 μm or less. Since the light emitting cells 111P, 113P, 115P have the above sizes, it is possible to relatively mount more light emitting cells 111P, 113P, 115P in the same area. Therefore, it is possible to improve the resolution of the display device.

[0111] According to an embodiment of the present invention, a wavelength converter 250 may be further provided on the light emitting cells 111P, 113P, and 115P. In the embodiment, the wavelength converter 250 may be provided only on some of the light emitting cells 111P, 113P, and 115P. For example, the wavelength converter 250 may be provided only on the second light emitting cell 113P. The wavelength converter 250 provided on the second light emitting cell 113P converts the wavelength band of the light emitted from the second light emitting cell 113P. The light after passing through the wavelength converter 250 is perceived as a different color from the light emitted from the second light emitting cell 113P. Furthermore, the wavelength of the light after passing through the wavelength converter 250 is different from the wavelength of the light emitted from the first light emitting cell 111P or the third light emitting cell 115P in which the wavelength converter 250 is not provided. The wavelength converter 250 may absorb light having a relatively short wavelength and then emit light having a longer wavelength than the wavelength of the absorbed light.

[0112] For example, when blue light is emitted from the first light emitting cell 111P and green light is emitted from the third light emitting cell 115P, the light emitted from the second light emitting cell 113P and passing through the wavelength converter 250 may be viewed as red light. In this case, the light emitted from the second light emitting cell 113P may be blue light, green light, ultraviolet light, etc. The blue light, green light, or ultraviolet light is converted into red light by the wavelength converter 250.

[0113] The wavelength converter 250 may include a phosphor layer 251 and a color filter 252. The phosphor layer 251 and the color filter 252 both perform the function of converting the wavelength of the received light into a specific wavelength band. In an embodiment of the present invention, the phosphor layer 251 and the color filter 252 may exhibit differences in the wavelength bandwidth of the converted and emitted light. For example, the color filter 252 may include a quantum dot material and may convert the received light into light with a relatively narrow bandwidth. In comparison, the phosphor layer 251 may convert the received light into light with a relatively wide bandwidth.

[0114] A red color filter 143 may be further provided on the wavelength converter 141. The color filter 143 may be omitted, and when the color filter 143 is provided, a more pure color can be realized.

[0115] The phosphor layer 251 may be provided in a form that fills the inside of the opening 222. Therefore, the light emitted from the light emitting cell 113P can pass through the phosphor layer 251 before being viewed by the user's eyes.

[0116] The phosphor layer 251 may be provided in a form in which PDMS (polydimethylsiloxane), PI (polyimide), PMMA (poly(methyl 2-methylpropenoate)) is mixed with a transparent or semi-transparent binder such as ceramic.

[0117] The color filters 252 are provided in a form spaced apart from the light emitting cells 113P. The width of the color filters 252 is greater than the width of the openings 222. Thus, a portion of the color filter layer 252 overlaps the barrier rib 220 in a plan view. The color filter layer 252 having the above-mentioned form can prevent light emitted from the light emitting cells 113P from being viewed by a user without passing through the color filters 252, and can also improve structural stability.

[0118] The color filter 252 can improve the color purity of light. Specifically, the color filter 252 can block blue light and ultraviolet light that are not completely converted by the phosphor layer 251. Also, the color filter 252 prevents color mixing of light emitted from the second light emitting cell 113P by blocking light from the adjacent first and third light emitting cells 111P and 115P. Therefore, according to an embodiment of the present invention, the phosphor layer 251 and the color filter 252 are provided in the wavelength converter 250, thereby further improving color purity.

[0119] According to an embodiment of the present invention, a protective layer 240 is provided on the light emitting cells 111P, 115P and the barrier ribs 220. The protective layer 240 is provided to fill the insides of the openings 221, 223 where the wavelength converter 250 is not provided, and to cover the surfaces of the barrier ribs 220.

[0120] The protective layer 240 is optically transparent. Therefore, the light emitted from the light emitting cells 111P, 115P or emitted through the wavelength converter 250 maintains its optical properties even when passing through the protective layer 240. The protective layer 240 is formed of an optically transparent material. The protective layer 240 may be formed of epoxy, polysiloxane, photoresist, or the like. For example, the polysiloxane material may be PDMS (polydimethylsiloxane). However, the material of the protective layer 240 is not limited thereto, and materials such as HSSQ (Hydrogen Silsesquioxane), MSSQ (Methyksilsesquioxane), polyimide, divinyl siloxane, DVS-BCS (bis-Benzocyclobutane), PFCB (Perfluorocyclobutane), PAE (Polyarylene Ether), and the like may be used.

[0121] The thickness of the protective layer 240 may be determined in consideration of the overall thickness of the display device including the substrate 210. For example, the protective layer 240 may be provided such that the distance from the rear surface of the substrate 210 to the upper surface of the protective layer 240 is about 1 mm or less. By providing the protective layer 240 to the above-mentioned thickness, the light emitting cells 111P, 115P under the protective layer 240 can be protected and the display device can be made thinner.

[0122] Fig. 6 is a cross-sectional view showing a light emitting cell according to an embodiment of the present invention, and since flip chip type light emitting diodes can be used as the first to third light emitting cells 111P, 113P, and 115P in an embodiment of the present invention, Fig. 6 is a cross-sectional view showing a simple flip chip type light emitting cell according to an embodiment of the present invention. The light emitting cell shown in Fig. 6 is any one of the first to third light emitting cells 111P, 113P, and 115P, and in this embodiment, the first light emitting cell 111P will be described as an example and is referred to as light emitting cell 111 in the drawings.

[0123] 6, the light emitting cell 111 includes a first conductive type semiconductor layer 1110, an active layer 1112, a second conductive type semiconductor layer 1114, a first contact layer 1116, a second contact layer 1118, an insulating layer 1120, a first terminal 1122, and a second terminal 1124.

[0124] The first conductive type semiconductor layer 1110, the active layer 1112, and the second conductive type semiconductor layer 1114 may be commonly referred to as semiconductor layers. The type of semiconductor layer may vary depending on the wavelength of light emitted by the light emitting cell. In one embodiment, in the case of a light emitting cell emitting green light, the semiconductor layer may include indium gallium nitride (InGaN), gallium nitride (GaN), gallium phosphide (GaP), aluminum gallium indium phosphide (AlGaInP), and aluminum gallium phosphide (AlGaP). In one embodiment, in the case of a light emitting cell emitting red light, the semiconductor layer may include aluminum gallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), aluminum gallium indium phosphide (AlGaInP), and gallium phosphide (GaP). In one embodiment, for a light emitting cell that emits blue light, the semiconductor layer may include gallium nitride (GaN), indium gallium nitride (InGaN), and zinc selenide (ZnSe).

[0125] The first conductive type semiconductor layer 1110 and the second conductive type semiconductor layer 1114 have opposite polarities. For example, when the first conductive type is n-type, the second conductive type is p-type, and when the second conductive type is p-type, the second conductive type is n-type. In one embodiment of the present invention, the first semiconductor layer 1110 is an n-type semiconductor layer 1110, and the second semiconductor layer 1114 is a p-type semiconductor layer 1114. Hereinafter, a case where the n-type semiconductor layer 1110, the active layer 1112, and the p-type semiconductor layer 1114 are formed in sequence will be described as an example.

[0126] The n-type semiconductor layer 1110, the active layer 1112, and the p-type semiconductor layer 1114 may be formed of a nitride-based semiconductor such as a III-V series nitride semiconductor, for example, (Al, Ga, In)N. The n-type semiconductor layer 1110, the active layer 1112, and the p-type semiconductor layer 1114 may be formed using a known method such as metal organic chemical vapor deposition (MOCVD). In addition, the n-type semiconductor layer 1110 includes n-type impurities (e.g., Si, Ge, Sn), and the p-type semiconductor layer 1114 includes p-type impurities (e.g., Mg, Sr, Ba). In one embodiment, the n-type semiconductor layer 1110 may include GaN or AlGaN including Si as a dopant, and the p-type semiconductor layer 1114 may include GaN or AlGaN including Mg as a dopant.

[0127] Although the n-type semiconductor layer 1110 and the p-type semiconductor layer 1114 are each illustrated as a single layer in the drawings, these layers may be multiple layers or may include a superlattice layer. The active layer 1112 may include a single quantum well structure or a multiple quantum well structure, and the composition ratio of the nitride-based semiconductor is adjusted to emit a desired wavelength. For example, the active layer 1112 may emit blue light or ultraviolet light.

[0128] A first contact layer 1116 is disposed on the first conductive type semiconductor layer 1110 where the active layer 1112 and the second conductive type semiconductor layer 1114 are not provided, and a second contact layer 1118 is disposed on the second conductive type semiconductor layer 1114.

[0129] The first and / or second contact layers 1116, 1118 may be made of a single layer or multiple layers of metal. The materials for the first and / or second contact layers 1116, 1118 may be metals such as Al, Ti, Cr, Ni, Au, and alloys thereof.

[0130] An insulating layer 1120 is provided on the first and second contact layers 1116, 1118, and a first terminal 1122 connected to the first contact layer 1116 through a contact hole and a second terminal 1124 connected to the second contact layer 1118 through a contact hole are provided on the insulating layer 1120.

[0131] The first terminal 1122 may be connected to one of the first connection electrode 121 and the second connection electrode 123 through the second conductive adhesive layer 163, and the second terminal 1124 may be connected to the remaining one of the first connection electrode 121 and the second connection electrode 123 through the second conductive adhesive layer 163.

[0132] The first and / or second terminals 1122, 1124 may be made of a single or multi-layer metal. The material of the first and / or second terminals 1122, 1124 may be metals such as Al, Ti, Cr, Ni, Au, and alloys thereof.

[0133] Although the light emitting cell has been described with reference to the drawings in an embodiment of the present invention, the light emitting cell may further include layers having additional functions in addition to the above-mentioned layers. For example, the light emitting cell may further include various layers such as a reflective layer for reflecting light, an additional insulating layer for insulating specific components, and a solder prevention layer for preventing solder diffusion.

[0134] In an embodiment of the present invention, the surface of the first conductive type semiconductor layer 1110 or the n-type semiconductor layer 1110 may include irregularities. That is, the surface from which light of the light emitting cells 111 is emitted may include irregularities. The provision of the irregularities may improve light extraction efficiency. The irregularities may be provided in various forms such as polygonal pyramids, hemispheres, randomly arranged surfaces having roughness, etc.

[0135] In addition to the above examples, when forming the flip-chip type light emitting cell 111, the mesa may be formed in various shapes, and the positions and shapes of the first and second contact layers 1116, 1118 and the first and second terminals 1122, 1124 may also be changed in various ways.

[0136] According to an embodiment of the present invention, the light emitting cell 111 is a vertical type light emitting cell. Even when the light emitting cell 111 is a vertical type light emitting cell, the first conductive type semiconductor layer 1110, the active layer 1112, and the second conductive type semiconductor layer 1114 may be provided in a sequentially stacked form. At this time, matters related to the first conductive type semiconductor layer 1110, the active layer 1112, and the second conductive type semiconductor layer 1114 are the same as those described in the description of the flip chip type light emitting cell 111.

[0137] 7a and 7b are plan views showing a pixel according to an embodiment of the present invention.

[0138] According to an embodiment of the present invention, the non-light-transmitting layer includes a plurality of openings, each of which is provided with one light-emitting cell, and the distance between the light-emitting cells provided in the same pixel is shorter than the distance between the light-emitting cells provided in different light-emitting pixels.

[0139] When light emitting cells are provided in the openings, the distance between the light emitting cells and the sidewalls of the openings is relatively small compared to the distance between the openings, so the following description will be based on different distances between the openings. However, the following description of the distance between the openings also applies to the distance between the light emitting cells. This is because the distance between the light non-transmitting layer sidewalls and the light emitting cells is narrow, less than 2 μm, and is a relatively short distance.

[0140] Each pixel 110, 110', 110" is provided with first to third light emitting cells. The first light emitting cell emits light of a first wavelength, and the second light emitting cell emits light of a second wavelength different from the first wavelength. Furthermore, the third light emitting cell emits light of a third wavelength different from the first wavelength. Therefore, in some cases, the second wavelength and the third wavelength may be the same, in which case a wavelength converter is provided on at least one of the second light emitting cell or the third light emitting cell.

[0141] Referring to FIG. 7a, each of the first pixel 100, the second pixel 110', and the third pixel 110" is provided with a first light emitting cell 221, 221', 221", a second light emitting cell 222, 222', 222", and a third light emitting cell 223, 223, 223", and each pixel 110, 110', 110" is arranged in a triangular shape.

[0142] At this time, the shortest distance between each of the openings 221, 222, 223 located in the first pixel 100 is shorter than the shortest distance between one of the openings located in the first pixel 100 and the most adjacent opening among the openings located in the other pixels 110', 110". For example, the second distance D2 and the fourth distance D4 are shorter than the first distance D1 and the third distance D3. At this time, the second distance D2 refers to the distance between the first opening 221 and the third opening 223, and the fourth distance D4 refers to the distance between the second opening 222 and the third opening 223. Furthermore, the first distance D1 refers to the distance between the third opening 223 of the first pixel 100 and the second opening 222' of the second pixel 110', and the third distance D3 refers to the distance between the third opening 223 of the first pixel 100 and the first opening 221" of the third pixel 110".

[0143] Therefore, the light emitted from the openings 221, 222, and 223 located in the first pixel 100 is mixed relatively easily, and therefore, highly pure white light can be realized. However, the light emitted from the first pixel 100 and the second pixel 110' or the first pixel 110' and the third pixel 110", which are different pixels, is not mixed with each other. Therefore, the display device according to the present invention can emit highly pure white light while not causing a problem of color change depending on the viewing angle at which the display device is viewed.

[0144] Referring to FIG. 7b, a first pixel 100, a second pixel 110', and a third pixel 110" are arranged with a first light emitting cell 221, 221', 221", a second light emitting cell 222, 222', 222", and a third light emitting cell 223, 223, 223". The first light emitting cell to the third light emitting cell in each pixel 110, 110', 110" are arranged sequentially in one direction, and the distance between the first light emitting cell and the second light emitting cell and the distance between the second light emitting cell and the third light emitting cell included in one pixel are shorter than the distance between different pixels.

[0145] For example, in each of the pixels 110, 110', and 110'', a first light emitting cell 221, 221', and 221'', a second light emitting cell 222, 222', and 222'', and a third light emitting cell 223, 223, and 223'' are sequentially arranged.

[0146] That is, in Fig. 7b, the second distance D2 and the fourth distance D4 are shorter than the first distance D1 and the third distance D3. At this time, the second distance D2 refers to the distance between the first opening 221' and the second opening 222' of the second pixel 110', and the fourth distance refers to the distance between the second opening 222' and the third opening 223' of the second pixel 110'. Furthermore, the first distance D1 refers to the distance between the second opening 222 of the first pixel 100 and the second opening 222' of the second pixel 110', and the third distance D3 refers to the distance between the second opening 222' of the second pixel 110' and the second opening 222" of the third pixel 110".

[0147] As described above, the distance from the sidewall of the non-light-transmitting layer that forms the opening to the light-emitting cell is relatively short compared to the distance between the openings, so the matters regarding the distance between the openings apply in the same manner as the matters regarding the distance between the light-emitting cells.

[0148] Since the distance between apertures or light emitting cells provided in the same pixel is shorter than the distance between apertures or light emitting cells provided in different pixels, the lights emitted from the apertures located in the same pixel are mixed relatively easily, and therefore, high purity white light can be realized. However, the lights emitted from the first pixel 100 and the second pixel 110' or the first pixel 110' and the third pixel 110" which are different pixels are not mixed with each other. Therefore, the display device according to the present invention can emit high purity white light without the problem of color changing depending on the viewing angle at which the display device is viewed.

[0149] Furthermore, the distance between the light emitting cells provided in the same pixel may be varied according to the type of light emitted by the light emitting cells.

[0150] Specifically, when the first light emitting cell emits red light, the second light emitting cell emits green light, and the third light emitting cell emits blue light, the following distance relationship may be established between the first light emitting cell to the third light emitting cell.

[0151] First, the distance between the first light emitting cell and the second light emitting cell may be the same as the distance between the first light emitting cell and the third light emitting cell, or the distance between the first light emitting cell and the second light emitting cell may be different from the distance between the second light emitting cell and the third light emitting cell.

[0152] The above-mentioned distance relationship takes into consideration the characteristics of each light emitting cell that emits light of different wavelengths. By arranging the light emitting cells as described above, it is possible to form white light with high purity while preventing unnecessary color mixing.

[0153] According to an embodiment of the present invention, the display device having the above-mentioned structure may be embodied in various forms without departing from the concept of the present invention. Figures 8a to 8d are cross-sectional views showing a display device according to an embodiment of the present invention.

[0154] 8a, a reflective layer 224 may be provided in the openings 221, 222, and 223. The reflective layer 224 is provided in a form covering a sidewall of the partition 220 forming the opening 223. Furthermore, the reflective layer 224 may be provided in a form covering a portion of the substrate 210. In an embodiment of the present invention, even when the reflective layer 224 covers a portion of the substrate 210, the reflective layer 224 does not contact the light emitting cell 115P.

[0155] When the reflective layer 224 is provided on the sidewall of the partition 220, the distance between each light emitting cell provided in the same pixel and the sidewall of the opening is less than about 5 μm. In this case, the reflective layer 224 reflects light, so there is no risk that the light emitted from the light emitting cell will transmit through the partition 220.

[0156] The reflective layer 224 may include metals such as silver (Ag), aluminum (Al), copper (Cu), platinum (Pt), gold (Au), etc. The reflective layer 224 has a relatively thin thickness. The reflective layer 224 may be formed by forming a thin film using chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), etc., and then using various patterning methods.

[0157] Referring to FIG. 8 b , a light blocking portion 260 and a diffusion plate 270 may be further provided on the protective layer 240 .

[0158] The light blocking portion 260 is provided so as not to overlap the openings 221, 222, and 223 on a plane, and therefore does not affect the total amount of light emitted from the light emitting cells 111P, 113P, and 115P. The light blocking portion 260 may be made of black photosensitive resist. When the light blocking portion 260 is made of black photosensitive resist, it is easy to pattern the light blocking portion 260 using photolithography. However, the material of the light blocking portion 260 is not limited thereto, and the light blocking portion 260 may be made of various materials.

[0159] The light blocking portion 260 is provided spaced apart from the barrier ribs 220 and, together with the barrier ribs 220, prevents the light emitted from the light emitting cells from being mixed with other colors.

[0160] The diffusion plate 270 refracts and diffuses the light emitted from the light emitting cells, thereby making it possible to further increase the viewing angle of the light emitted from the light emitting cells.

[0161] The diffusion plate 270 may be formed using a transparent polymer such as HSSQ (Hydrogen Silsesquioxane), MSSQ (Methyksilsesquioxane), polyimide, divinyl siloxane, DVS-BCS (bis-Benzocyclobutane), PFCB (Perfluorocyclobutane), PAE (Polyarylene Ether), PMMA (Polymethylmethacrylate), or PDMS (Polydimethylsiloxane).

[0162] 8b, the openings 221, 222, and 223 have a shape in which the width increases as they are spaced apart from the substrate 210. Specifically, a lower width W2 of the opening 221 is smaller than an upper width W1 of the opening 221. Therefore, the partitions 220 provided between the openings 221, 222, and 223 have an inverted trapezoidal cross section. Specifically, the width of the partitions 220 increases as they are spaced apart from the substrate 210.

[0163] The openings 221, 222, and 223 having the above-mentioned shapes can prevent unnecessary color mixing of the lights emitted from the light emitting cells 111P, 113P, and 115P, and at the same time, can ensure a wider viewing angle.

[0164] 8c, a window layer 280 is further provided on the diffusion plate 270. The window layer 280 may include glass, acrylic, etc., and is optically transparent. Therefore, the window layer 280 does not affect the optical properties of the light emitted from the light emitting cells. Furthermore, the window layer 280 may have flexibility.

[0165] The window layer 280 can protect the light emitting cells and function as a support. Specifically, the barrier ribs 220 can be supported on the window layer 280.

[0166] Furthermore, according to an embodiment, the first to third light emitting cells 111P, 113P, and 115P are supported by a window layer 280. The window layer 280 may support a plurality of light emitting cells, and one window layer 280 may support 1 to 100 light emitting cells. Therefore, by attaching a plurality of window layers 280, each supporting a plurality of light emitting cells, to the substrate 210, a display device with high resolution may be easily realized.

[0167] Referring to FIG. 8d, wavelength converters 250, 250′, and 250″ are provided on the first light emitting cell 111P, 113P, and 115P. In this case, the first light emitting cell 111P, 113P, and 115P can all emit light of the same wavelength. Furthermore, the semiconductor layers of the first light emitting cell 111P, 113P, and 115P may include aluminum gallium indium nitride (AlGaInN).

[0168] When the first to third light emitting cells 111P, 113P, and 115P emit light of the same wavelength, different wavelength converters 250, 250', and 250" are provided on each light emitting cell. These wavelength converters 250, 250', and 250" receive the light emitted from the light emitting cells and convert it into light of different wavelengths. Therefore, red light, blue light, and green light can be emitted from one pixel.

[0169] In one embodiment of the present invention, the first to third light emitting cells can be easily mounted and replaced, and can be configured in various forms to operate with optimal light emitting efficiency. In the following embodiments, the terms "first", "second", "third", etc. may be used to refer to components different from those in the above-described embodiments for the convenience of explanation.

[0170] FIG. 9 is a schematic plan view illustrating a pixel 100 according to an embodiment of the present invention, and FIG. 10 is a schematic cross-sectional view taken along line AA in FIG.

[0171] 9 and 10, the pixel 100, i.e., the light emitting element, includes a substrate 21, a first light emitting cell 30a, a second light emitting cell 30b, a third light emitting cell 30c, a transparent electrode layer 31, pads 33a, 33b, a first wavelength converter 51a, a second wavelength converter 51b, a third wavelength converter 51c, a first color filter 53a, a second color filter 53b, a third color filter 53c, and a partition 55 (or a partition). The first to third light emitting cells 30a, 30b, and 30c each include a first conductive type semiconductor layer 23, an active layer 25, and a second conductive type semiconductor layer 27. The pixel 100 also includes sub-pixels 10B, 10G, and 10R, and the sub-pixels 10B, 10G, and 10R each include light emitting cells 30a, 30b, and 30c, wavelength converters 51a, 51b, and 51c, and color filters 53a, 53b, and 53c.

[0172] The substrate 21 is not particularly limited as long as it is a substrate on which a gallium nitride-based semiconductor layer can be grown. Examples of the substrate 21 include a sapphire substrate, a gallium nitride substrate, a SiC substrate, and the like, and is a patterned sapphire substrate. The substrate 21 may have a rectangular or square outer shape as shown in the plan view of FIG. 9, but is not necessarily limited thereto. The size of the substrate 21 can be determined according to the required pixel size. For example, the size of the long side of the substrate 21 is 400 μm or less, and further 100 μm or less.

[0173] The first to third light emitting cells 30a, 30b, and 30c are spaced apart from each other. As shown in Fig. 9, the first to third light emitting cells 30a, 30b, and 30c have different areas. The second light emitting cell 30b has a larger area than the first light emitting cell 30a, and the third light emitting cell 30c has a larger area than the second light emitting cell 30b. The areas of the first to third light emitting cells 30a, 30b, and 30c may be determined in consideration of the light conversion efficiency of the wavelength converters 51a, 51b, and 51c, which will be described later.

[0174] Meanwhile, the first to third light emitting cells 30a, 30b, and 30c may be disposed adjacent to each other. That is, the first light emitting cell 30a may be adjacent to the second and third light emitting cells 30b and 30c, the second light emitting cell 30b may be adjacent to the first and third light emitting cells 30a and 30c, and the third light emitting cell 30c may be adjacent to the first and second light emitting cells 30a and 30b. As shown in FIG. 9, the first and second light emitting cells 30a and 30b may be arranged along the major axis of the third light emitting cell 30c. However, the present invention is not limited thereto, and the cells may be arranged in various other shapes. For example, one light emitting cell may be disposed between two other light emitting cells. The first to third light emitting cells 30a, 30b, and 30c may have a rectangular shape, but the present invention is not limited thereto, and the cells may have various shapes.

[0175] Each of the first to third light emitting cells 30a, 30b, and 30c includes a first conductive type semiconductor layer 23, an active layer 25, and a second conductive type semiconductor layer 27. The first conductive type semiconductor layer 23 is disposed on a substrate 21. The first conductive type semiconductor layer 23 is a layer grown on the substrate 21, and is a gallium nitride based semiconductor layer doped with impurities, for example, Si.

[0176] An active layer 25 and a second conductive type semiconductor layer 27 are disposed on the first conductive type semiconductor layer 23. The active layer 25 is disposed between the first conductive type semiconductor layer 23 and the second conductive type semiconductor layer 27. The active layer 25 and the second conductive type semiconductor layer 27 may have an area smaller than that of the first conductive type semiconductor layer 23. The active layer 25 and the second conductive type semiconductor layer 27 may be partially removed to expose a portion of the first conductive type semiconductor layer 23.

[0177] The active layer 25 may have a single quantum well structure or a multiple quantum well structure. The composition and thickness of the well layer in the active layer 25 determine the wavelength of the light generated. In particular, an active layer that generates ultraviolet or blue light can be provided by adjusting the composition of the well layer. In this embodiment, the active layers 25 of the first light emitting cell 30a, the second light emitting cell 30b and the third light emitting cell 30c are all grown on the same substrate 21 under the same conditions, and therefore have the same composition and thickness, and therefore emit light of the same wavelength.

[0178] Meanwhile, the second conductive type semiconductor layer 27 is a gallium nitride-based semiconductor layer doped with p-type impurities, for example, Mg. The first conductive type semiconductor layer 23 and the second conductive type semiconductor layer 27 are each a single layer, but are not limited thereto, and may be a multilayer or may include a superlattice layer. The first conductive type semiconductor layer 23, the active layer 25, and the second conductive type semiconductor layer 27 may be formed by growing them on the substrate 21 in a chamber using a known method such as metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0179] The transparent electrode layer 31 is disposed on the second conductivity type semiconductor layer 27 and is in ohmic contact with the second conductivity type semiconductor layer 27. The transparent electrode layer 31 may include, for example, Ni / Au, ITO, or ZnO.

[0180] Meanwhile, a first pad 33a and a second pad 33b are disposed on the first to third light emitting cells 30a, 30b, and 30c, respectively. The first pad 33a and the second pad 33b may be disposed near the edge of the substrate 21 as shown in Fig. 9, so that wires can be easily connected when mounting on a circuit board or the like. The first pad 33a is electrically connected to the first conductive type semiconductor layer 23, and the first pad 33b is electrically connected to the second conductive type semiconductor layer 27. The first pad 33a may be disposed on the first conductive type semiconductor layer 23 exposed by partially removing the second conductive type semiconductor layer 27 and the active layer 25, and the second pad 33b may be disposed on the transparent electrode layer 31.

[0181] The first wavelength converter 51a is disposed on the first light emitting cell 30a, the second wavelength converter 51b is disposed on the second light emitting cell 30b, and the third wavelength converter 51c is disposed on the third light emitting cell 30c. The first to third wavelength converters 51a, 51b, and 51c may be located on the transparent electrode layer 31, respectively.

[0182] The first wavelength converter 51a converts the wavelength of light emitted from the first light emitting cell 30a, the second wavelength converter 51b converts the wavelength of light emitted from the second light emitting cell 30b, and the third wavelength converter 51c converts the wavelength of light emitted from the third light emitting cell 30c. Here, the second wavelength converter 51b converts light to a longer wavelength than the first wavelength converter 51a, and the third wavelength converter 51c converts light to a longer wavelength than the second wavelength converter 51b. For example, the first to third light emitting cells 30a, 30b, and 30c can emit ultraviolet light, the first wavelength converter 51a can convert the ultraviolet light to blue light, the second wavelength converter 51b can convert the ultraviolet light to green light, and the third wavelength converter 51c can convert the ultraviolet light to red light.

[0183] Meanwhile, a first color filter 53a, a second color filter 53b and a third color filter 53c are disposed on the first to third wavelength converters 51a, 51b and 51c, respectively, to filter the light emitted from the wavelength converters. For example, the first color filter 53a filters light other than blue light, the second color filter 53b filters light other than green light, and the third color filter 53c filters light other than red light. By using the first to third color filters 53a, 53b and 53c, the color purity of blue light, green light and red light can be improved.

[0184] In this embodiment, the active layer 25 emits ultraviolet light, but the active layer 25 may emit blue light. In this case, the first wavelength converter 51a may be omitted, and a transparent resin may be disposed in place of the first wavelength converter 51a. Meanwhile, the second wavelength converter 51b converts blue light to green light, and the third wavelength converter 51c converts blue light to red light.

[0185] Meanwhile, the partition walls 55 are disposed between the first to third light emitting cells 30a, 30b, and 30c. The partition walls 55 may also surround each light emitting cell. The partition walls 55 may also be disposed between the wavelength converters 51a, 51b, and 51c.

[0186] The partition 55 prevents light interference between the sub-pixels 10B, 10G, and 10R by blocking light emitted from one light emitting cell from traveling to another light emitting cell. The partition 55 may fill the area between the light emitting cells, but is not limited thereto. The partition 55 may be formed of a white resin or a photosensitive solder resist capable of reflecting light.

[0187] The pixel of the present embodiment has three sub-pixels 10B, 10G, and 10R, which are fixed on the substrate 21. For example, the sub-pixel 10B may realize blue light by the light emitting cell 10a or by a combination of the first light emitting cell 10a and the first wavelength converter 51a, the sub-pixel 10G may realize green light by a combination of the second light emitting cell 10B and the second wavelength converter 51b, and the sub-pixel 10R may realize red light by a combination of the third light emitting cell 10c and the third wavelength converter 51c.

[0188] According to the present embodiment, the three sub-pixels 10B, 10G, and 10R may be mounted on a circuit board together with the substrate 21. In the case of conventional micro LEDs, the sub-pixels are mounted individually, which requires many steps and makes the mounting process difficult. In contrast, in the present embodiment, one pixel includes three sub-pixels and is embodied as one light emitting element, so the size of the light emitting element is relatively larger than that of a micro LED, which reduces the number of mounting steps and makes mounting easier.

[0189] Meanwhile, in this embodiment, the first to third light emitting cells 30a, 30b, and 30c occupy different areas from each other. In addition, the wavelength converters 51a, 51b, and 51c disposed on these light emitting cells also occupy different areas from each other. The relative areas of the light emitting cells are closely related to the light conversion efficiency of the wavelength converters, and may also be related to the color filtering efficiency of the color filters 53a, 53b, and 53c.

[0190] Wavelength converters can generally include phosphors, for example beta-sialon (SiAlON) is suitable for emitting green light, and CASN (CaAlSiN) series phosphors are suitable for emitting red light.

[0191] However, phosphors do not convert all blue light into green light or red light, and each phosphor has a certain light conversion efficiency. In particular, a red phosphor that converts ultraviolet light or blue light of the same wavelength into red light has a lower light conversion efficiency than a green phosphor that converts the same wavelength into green light. In addition, red light also has a lower luminosity than green light. Therefore, when the first to third light emitting cells 30a, 30b, and 30c are formed in the same area, the third light emitting cell 30c of the sub-pixel 10R that realizes red light must be driven under a higher current density to realize a sensitivity of the same intensity as the other sub-pixels 10B and 10G. The second light emitting cell 30b of the sub-pixel 10G that realizes green light must also be driven under a higher current density than the first light emitting cell 30a. That is, the current density required to realize a normal image differs for each light emitting cell, and therefore, a problem occurs that the first to third light emitting cells 30a, 30b, and 30c cannot be driven under an optimal light emitting efficiency condition.

[0192] In this embodiment, the areas of the first to third light emitting cells 30a, 30b, and 30c are made different, and the current densities for driving the light emitting cells are made equal or substantially equal, so that the light emitting cells can be driven under optimal light emitting efficiency conditions.

[0193] The relative areas of the first to third light emitting cells 30a, 30b, and 30c are determined in consideration of the relative light conversion efficiencies of the first to third wavelength converters 51a, 51b, and 51c. The smaller the light conversion efficiency of the wavelength converter, the larger the area of ​​the corresponding light emitting cell.

[0194] For example, when the first to third light emitting cells 30a, 30b, and 30c emit blue light, the first wavelength converter 51a is omitted, and the area ratios of the second and third light emitting cells 30b and 30c to the first light emitting cell 30a may be inversely proportional to the light conversion efficiency of the second and third wavelength converters 51b and 51c, respectively. In a specific example, when the second wavelength converter 51b includes beta-sialon and the third wavelength converter includes CASN, the relative area ratios of the first light emitting cell 30a, the second light emitting cell 30b, and the third light emitting cell 30c are 1:2:7.

[0195] In addition, when the first to third light emitting cells 30a, 30b, and 30c emit ultraviolet rays, the area ratio of the second light emitting cell 30b and the third light emitting cell 30c to the first light emitting cell 30a can be inversely proportional to the optical conversion efficiency ratio of the second wavelength converter 51b to the first wavelength converter 51a and the optical conversion efficiency ratio of the third wavelength converter 51c, respectively.

[0196] In this embodiment, the area of ​​the light emitting cell is determined taking into consideration the light conversion efficiency of the wavelength converter. However, if the filtering efficiencies of the first to third color filters 53a, 53b, and 53c are different from each other, the area of ​​the light emitting cell can be determined taking into consideration the efficiency difference.

[0197] According to the present embodiment, the first to third light emitting cells 30a, 30b, and 30c may have different areas and be driven under the same current density, so that the current density for driving the light emitting cells can be set to an optimal condition, thereby improving the light emitting efficiency.

[0198] FIG. 11 is a schematic plan view illustrating a light emitting device 200 according to another embodiment of the present invention, and FIG. 12 is a schematic cross-sectional view taken along the cut line BB in FIG.

[0199] 11 and 12, the light emitting device 200 according to the present embodiment is generally similar to the light emitting device 100 described with reference to Figures 9 and 10, but is different in that the first to third light emitting cells 30a, 30b, and 30c share the first conductive type semiconductor layer 23. That is, the first conductive type semiconductor layer 23 of the first light emitting cell 30a, the first conductive type semiconductor layer 23 of the second light emitting cell 30b, and the first conductive type semiconductor layer 23 of the third light emitting cell 30 are continuously connected to each other.

[0200] Meanwhile, the first pads 33a are formed on the shared first conductive type semiconductor layer 23, and therefore the number of first pads 33a can be reduced compared to the previous embodiment, thereby ensuring a sufficient light emitting area.

[0201] Further, the extension portion 33c may be extended from the first pad 33a. The extension portion 33c may extend to an area between the light emitting cells. The extension portion 33c may be disposed to surround each light emitting cell, or may be disposed on a part of an edge of each light emitting cell as shown in FIG. 11. In particular, when the second pad 33b is disposed near one corner of the light emitting cell, the extension portion may be disposed adjacent to an edge away from the corner, thereby preventing current from concentrating in a specific part of the light emitting cell and improving light efficiency.

[0202] Figure 13 is a schematic plan view for illustrating a light-emitting element 300 according to another embodiment of the present invention, Figure 14 is a schematic cross-sectional view taken along the cutting line CC in Figure 13, and Figure 15 is a schematic enlarged cross-sectional view taken along the cutting line DD in Figure 13.

[0203] 13 to 15, the light emitting device 300 according to the present embodiment is different from the light emitting device 100 or 200 having light emitting cells of a horizontal structure in that the light emitting cells 30a, 30b, and 30c have a vertical structure.

[0204] The light emitting device 300 according to the present embodiment may include a supporting substrate 121, a first light emitting cell 30a, a second light emitting cell 30b, a third light emitting cell 30c, an anti-reflection layer 131, a pad 133b, a first wavelength converter 51a, a second wavelength converter 51b, a third wavelength converter 51c, a first color filter 53a, a second color filter 53b, a third color filter 53c, a partition 55 (or partition), a first insulating layer 35, a first electrode 39, a second electrode 36, a second insulating layer 37, a protective metal layer 41, and a bonding metal layer 45. The first to third light emitting cells 30a, 30b, and 30c each include a first conductive type semiconductor layer 23, an active layer 25, and a second conductive type semiconductor layer 27. The light emitting device 300 includes sub-pixels 10B, 10G, and 10R, and each of the sub-pixels 10B, 10G, and 10R includes light emitting cells 30a, 30b, and 30c, wavelength converters 51a, 51b, and 51c, and color filters 53a, 53b, and 53c.

[0205] The support substrate 121 is a secondary substrate bonded to an already grown compound semiconductor layer, which is different from a growth substrate for growing a compound semiconductor layer. The support substrate 51 is a conductive substrate, for example, a metal substrate or a semiconductor substrate. To form the light emitting cells 30a, 30b, and 30c, the first conductive type semiconductor layer 23, the active layer 25, and the second conductive type semiconductor layer 27 are grown on a growth substrate such as the substrate 21 described above, and then, after bonding the support substrate 121, the growth substrate is removed using a peeling technique such as laser lift-off or chemical lift-off.

[0206] The first to third light emitting cells 30a, 30b, and 30c are generally similar to the light emitting cells described above, but are arranged to emit light toward the first conductive type semiconductor layer 23. In addition, the light emitting cells 30a, 30b, and 30c may have through holes 30h or grooves that penetrate the second conductive type semiconductor layer 27 and the active layer 25 to expose the first conductive type semiconductor layer 23.

[0207] First conductivity type semiconductor layer 23, active layer 25, and second conductivity type semiconductor layer 27 are similar to those described in the previous embodiment, and therefore detailed description will be omitted to avoid duplication.

[0208] Meanwhile, roughness may be formed on the surface of the first conductive type semiconductor layer 23, and the anti-reflective layer 131 may cover the roughness. The anti-reflective layer 131 may also cover the side surfaces of the light emitting cells 30a, 30b, and 30c. The roughness may be formed using a wet etching technique such as light enhanced chemical etching, and the anti-reflective layer 131 may be formed using an atomic layer deposition technique. The anti-reflective layer 131 may have a layer structure of, for example, SiO2 / Al2O3 / SiO2, and may be formed according to the undulations of the roughness.

[0209] 15, the first insulating layer 35 is disposed between the first to third light emitting cells 30a, 30b, and 30c and the supporting substrate 121. The first insulating layer 35 may also cover the side surfaces of the active layer 25 and the second conductive type semiconductor layer 27 exposed in the through holes 30h. Meanwhile, the insulating layer 35 exposes the bottom surface of the second conductive type semiconductor layer 27.

[0210] The first insulating layer 35 may be a single layer or multiple layers of silicon oxide or silicon nitride, or may include a distributed Bragg reflector in which insulating layers having different refractive indices are repeatedly stacked. When the insulating layer 35 includes a distributed Bragg reflector, the insulating layer 35 may also include an interface layer between the distributed Bragg reflector and the second conductive semiconductor layer 27. The insulating layer 35 may include, for example, SiO2, MgF2, TiO2, or Nb2O5, and may include, for example, a distributed Bragg reflector in which TiO2 / SiO2 or Nb2O5 / SiO2 are repeatedly stacked on a SiO2 or MgF2 interface layer.

[0211] The second electrode 36 may include an ohmic reflective layer 32 and a barrier metal layer 34. The ohmic reflective layer 32 is in ohmic contact with the second conductive type semiconductor layer 27 exposed through the opening of the insulating layer 35. The ohmic reflective layer 32 may be in contact with the insulating layer 35, but as shown, the edge of the ohmic reflective layer 32 may be spaced apart from the insulating layer 35. The ohmic reflective layer 32 may include a reflective layer such as Ag, and may include a metal layer for ohmic contact such as Ni. The ohmic reflective layer 32 is located within a limited area under the second conductive type semiconductor layer 27.

[0212] Meanwhile, the barrier metal layer 34 is located between the ohmic reflective layer 32 and the support substrate 51 and covers the ohmic reflective layer 32. The barrier metal layer 34 prevents migration of metal materials, such as Ag, in the ohmic reflective layer 32. The barrier metal layer 34 may cover the side surfaces of the ohmic reflective layer 32, or may be disposed on the ohmic reflective layer 32 so that the side surfaces of the ohmic reflective layer 32 are exposed, as shown in FIG. 15. By exposing the side surfaces of the ohmic reflective layer 32, the ohmic reflective layer 32 can be formed in a relatively wide area, thereby reducing the contact resistance and the forward voltage. The barrier metal layer 35 may include, for example, Pt, Ni, Ti, W, Au, or an alloy thereof.

[0213] Meanwhile, the barrier metal layer 34 may also cover the insulating layer 35 inside the recesses of the light emitting cells 30a, 30b, 30c and may be electrically connected to the pads 33b formed in the recesses.

[0214] The second insulating layer 37 covers the barrier metal layer 34 below the barrier metal layer 34. The second insulating layer 37 can cover the entire lower surface of the barrier metal layer 34. Furthermore, the second insulating layer 37 can cover the side surfaces of the barrier metal layer 34 to prevent the side surfaces of the barrier metal layer 34 from being exposed to the outside.

[0215] The second insulating layer 37 may be a single layer or multiple layers of silicon oxide or silicon nitride, or may include a distributed Bragg reflector in which insulating layers having different refractive indices, such as SiO2 / TiO2 or SiO2 / Nb2O5, are repeatedly stacked. When the second insulating layer 37 includes a distributed Bragg reflector, the second insulating layer 37 may also include an interface layer between the distributed Bragg reflector and the first insulating layer 31. The first insulating layer 37 may include, for example, SiO2, MgF2, TiO2, or Nb2O5, and may include, for example, a distributed Bragg reflector in which TiO2 / SiO2 or Nb2O5 / SiO2 are repeatedly stacked on a SiO2 or MgF2 interface layer.

[0216] Meanwhile, the first electrode 39 is located between the second insulating layer 37 and the support substrate 51, and is electrically connected to the first conductivity type semiconductor layer 23 through the first insulating layer 35 and the second insulating layer 37. The first electrode 39 is located between the second electrode 34 and the support substrate 51, and the first electrode 39 can be connected to the first conductivity type semiconductor layer 23 exposed through the through hole 30h. Furthermore, the first electrode 39 is insulated from the active layer 25 and the second conductivity type semiconductor layer 27 by the first insulating layer 35 and the second insulating layer 37.

[0217] The first electrode 39 may include an ohmic layer in ohmic contact with the first conductivity type semiconductor layer 23, and may also include a reflective metal layer. For example, the first electrode 39 may include Cr / Au, and may further include Ti / Ni.

[0218] Meanwhile, a protective metal layer 41 may cover the lower surface of the first electrode 39. The protective metal layer 41 protects the first electrode 39 by preventing diffusion of metal materials such as Sn from the bonding metal layer 45. The protective metal layer 41 may include, for example, Au, and may further include Ti and Ni. The protective metal layer 41 may be formed, for example, by repeatedly stacking Ti / Ni a number of times and then stacking Au.

[0219] Meanwhile, the supporting substrate 121 is bonded onto the protective metal layer 41 through a bonding metal layer 45. The bonding metal layer 45 may be formed using, for example, AuSn or NiSn. Alternatively, the supporting substrate 121 may be formed on the protective metal layer 41 using, for example, a plating technique. When the supporting substrate 121 is a conductive substrate, it may function as a pad. Therefore, the first conductive semiconductor layers 23 of the first to third light emitting cells 30a, 30b, and 30c are electrically connected to each other, and the supporting substrate 121 is used as a common electrode.

[0220] Meanwhile, each of the light emitting cells 30a, 30b, 30c may have a recessed portion at one corner where the first conductive type semiconductor layer 23, the active layer 25, and the second conductive type semiconductor layer 27 are removed, and each of the pads 133b is disposed within the recessed portion and electrically connected to the barrier metal layer 34.

[0221] The first to third wavelength converters 51a, 51b, and 51c and the first to third color filters 53a, 53b, and 53c are disposed on the first to third light emitting cells 30a, 30b, and 30c, respectively, to form sub-pixels 10B, 10G, and 10R.

[0222] 9 and 10, detailed description of the first to third wavelength converters 51a, 51b, 51c and the first to third color filters 53a, 53b, 53 will be omitted to avoid duplication. However, while the wavelength converters 51a, 51b, 51c are disposed on the second conductivity type semiconductor layer 27 side in the previous embodiment, the first to third wavelength converters 51a, 51b, 51c and the first to third color filters 53a, 53b, 53 are disposed on the first conductivity type semiconductor layer 23 side in this embodiment because the light emitting cells 30a, 30b, 30c have a vertical structure.

[0223] The partition wall 55 is disposed in the area between the light emitting cells 30a, 30b, and 30c and may surround the light emitting cells. The partition wall 55 may also surround the side of the pad 133b. The partition wall 55 is a white resin or a photosensitive solder resist having a light reflecting function as described above.

[0224] In addition, in this embodiment, the first to third light emitting cells 30a, 30b, and 30c occupy different areas from each other, which is the same as that described with reference to FIGS. 9 and 10, and therefore detailed description thereof will be omitted.

[0225] Fig. 16 is a schematic plan view illustrating a light emitting device 400 according to another embodiment of the present invention, and Fig. 17 is a schematic cross-sectional view taken along the cut line EE in Fig. 16. The light emitting device 400 according to this embodiment differs from the light emitting device of the previous embodiment in that it has a flip-type structure.

[0226] 16 and 17, the light emitting device 400 according to the present embodiment may include a substrate 21, first to third light emitting cells, an ohmic reflective layer 231, a first insulating layer 233, pad electrodes 235a, 235b, a second insulating layer 237, a first wavelength converter 51a, a second wavelength converter 51b, a third wavelength converter 51c, a first color filter 53a, a second color filter 53b, a third color filter 53c, and a partition 55 (or a partition). The first to third light emitting cells 30a, 30b, and 30c each include a first conductive type semiconductor layer 23, an active layer 25, and a second conductive type semiconductor layer 27. The light emitting device 400 also includes sub-pixels 10B, 10G, and 10R, and the sub-pixels 10B, 10G, and 10R each include a light emitting cell 30, a wavelength converter 51a, 51b, and 51c, and a color filter 53a, 53b, and 53c.

[0227] 9 and 10, detailed description thereof will be omitted. The first conductivity type semiconductor layer 23, the active layer 25, and the second conductivity type semiconductor layer 27 are also similar to the previous embodiment, and detailed description thereof will be omitted.

[0228] The light emitting cells are disposed under the substrate 21, and the first conductive type semiconductor layer 23 of the light emitting cells is exposed through the second conductive type semiconductor layer 27 and the active layer 25. The areas and stacked structures of these light emitting cells are similar to those of the first to third light emitting cells 30a, 30b, and 30c described in the previous embodiment, and therefore detailed description thereof will be omitted.

[0229] The ohmic reflective layer 231 is in ohmic contact with the second conductive semiconductor layer 27 of each light emitting cell. The ohmic reflective layer 231 may include an ohmic layer and a reflective layer, for example, an ohmic layer such as Ni or ITO and a reflective layer such as Ag or Al. The ohmic reflective layer 231 may also include an insulating layer such as SiO2 between a transparent oxide layer such as ITO and the reflective layer, and the reflective layer may be connected to the transparent oxide layer through the insulating layer.

[0230] The first insulating layer 233 covers the light emitting cells and covers the exposed side surfaces of the second conductive type semiconductor layer 27 and the active layer 25. The first insulating layer 233 has an opening that exposes the first conductive type semiconductor layer 23 and the ohmic reflective layer 231. The first insulating layer 233 may be formed of a single layer such as SiO2 or Si3N4, but is not limited thereto, and may be formed of multiple layers. In particular, the first insulating layer 233 may include a distributed Bragg reflector.

[0231] A first pad electrode 235a and a second pad electrode 235b are disposed on the first insulating layer 233. The first pad electrode 235a and the second pad electrode 235b are disposed on each light emitting cell, with the first pad electrode 235a electrically connected to the first conductive type semiconductor layer 23 and the second pad electrode 235b electrically connected to the ohmic reflective layer 231. The first pad electrode 235a and the second pad electrode 235b may be formed together in the same process and therefore may be located at the same level. In certain embodiments, the second pad electrode 235b may be omitted.

[0232] The second insulating layer 237 covers the first and second pad electrodes 235a, 235b and has an opening to expose them. The second insulating layer 237 may be formed of a single layer such as SiO2 or Si3N4, but is not limited thereto, and may be formed of multiple layers. In particular, the first insulating layer 233 may include a distributed Bragg reflector.

[0233] Meanwhile, first and second bump pads 243a, 243b are formed on each light emitting cell and connected to the first and second pad electrodes 235a, 235b through the openings in the second insulating layer 237. Specifically, the first bump pad 243a is connected to the first pad electrode 235a, and the second bump pad 243b is connected to the second pad electrode 235b.

[0234] The bump pads 243a, 243b may occupy a relatively larger area than the pads of the previously described embodiments, and the maximum width of the bump pads 243a, 243b may be at least half the minimum width of the light emitting cell. The bump pads 243a, 243b may have a rectangular shape as shown, but are not limited thereto, and may have a circular or elliptical shape. The bump pads 243a, 243b may include Au or AuSn.

[0235] Meanwhile, in addition to the bump pads 243a and 243b, a dummy bump pad 243c may be disposed on at least one light emitting cell. In particular, since the light emitting cells have different areas, the dummy bump pad 243c is disposed on the light emitting cell having a relatively large area. The dummy bump pad 243c can be used as a heat dissipation path for dissipating heat generated in the light emitting cell, thereby improving the light efficiency of the light emitting device.

[0236] The support member 245 may cover the sides of the bump pads 243a and 243b. The support member 245 may also cover the side of the dummy bump pad 243c. The support member 245 may be formed of a thermosetting or thermoplastic resin.

[0237] Meanwhile, the first to third wavelength converters 51a, 51b, and 51c are disposed on the substrate 21 facing the light emitting cells. The first to third wavelength converters 51a, 51b, and 51c are disposed on the corresponding light emitting cells. Also, the first to third color filters 53a, 53b, and 53c are disposed on the first to third wavelength converters 51a, 51b, and 51c, respectively. The first to third wavelength converters 51a, 51b, and 51c and the first to third color filters 53a, 53b, and 53c are the same as those described above, so detailed description thereof will be omitted.

[0238] Meanwhile, the partitions 55 may be located between the wavelength converters 51a, 51b, and 51c. The partitions 55 may be formed of a white resin or a photosensitive solder resist. In the previous embodiment, the partitions 55 are located between the light emitting cells 30a, 30b, and 30c. However, in this embodiment, the partitions 55 are located on the upper part of the substrate 21, and therefore the partitions 55 are not formed in the regions between the light emitting cells. Instead, the first insulating layer 233 may include a distributed Bragg reflector, or the first pad electrode 235a and / or the second pad electrode 235b may be arranged to cover the sidewalls of the light emitting cells, thereby preventing optical interference between the light emitting cells.

[0239] According to the present embodiment, the light emitting efficiency of each light emitting cell can be improved by using the light emitting cells having a flip-type structure. Also, in the present embodiment, the light emitting cells have different areas, and the areas of the light emitting cells are determined in consideration of the light conversion efficiency of the wavelength converter, as described above.

[0240] FIG. 18 is a schematic cross-sectional view illustrating a light emitting device 500 according to another embodiment of the present invention.

[0241] 18, light emitting device 500 according to this embodiment is generally similar to the light emitting device described with reference to FIGS. 16 and 17, but differs in that substrate 21 is omitted. First to third wavelength converters 51a, 51b, 51c are disposed on the light emitting cells instead of on substrate 21. In addition, as described with reference to FIGS. 13 to 15, roughness may be formed on the surface of first conductive type semiconductor layer 23, and an anti-reflection layer may cover the surface of first conductive type semiconductor layer 23.

[0242] In this embodiment, the light emitting cells may be supported by a support member 245 .

[0243] According to this embodiment, by removing the substrate 21, it is possible to block optical interference between the adjacent sub-pixels 10B, 10G, and 10R.

[0244] 19a and 19b are cross-sectional views illustrating a film including a wavelength converter.

[0245] 19a, in the previous embodiment, the first to third wavelength converters 51a, 51b, 51c are separately attached or formed on the light emitting cells 30a, 30b, 30c, but in this embodiment, the first to third wavelength converters 51a, 51b, 51c are arranged in one layer within one film, and transparent or opaque resin 151 is disposed in the areas between the wavelength converters 51a, 51b, 51c.

[0246] In this embodiment, when the light emitting cell emits blue light, the first wavelength converter 51a may be omitted, and in this case, a transparent resin 151 may be placed in the position of the first wavelength converter 51a.

[0247] 19b, the film according to this embodiment is a laminated film of various layers, for example, first layer 151a includes first wavelength converter 51a, second layer 151b includes second wavelength converter 51b, and third layer 151c includes third wavelength converter 51c. Each of the first to third layers is formed by combining transparent resin 151 and a wavelength converter. Meanwhile, when the light emitting cell emits blue light, first layer 151a may be omitted.

[0248] Although some examples have been described in this embodiment, films having various other structures may also be used.

[0249] FIG. 20 is a schematic plan view for explaining a display device according to one embodiment of the present invention.

[0250] Referring to FIG. 20, the display device according to the present embodiment includes a circuit board 150 and a light emitting device 100 arranged on the circuit board 150 .

[0251] The light emitting device 100 includes the first to third sub-pixels 10B, 10G, and 10R as the light emitting device described with reference to FIGS. 9 and 10, and also includes pads 33a and 33b.

[0252] The circuit board 150 has circuit wiring for supplying current to the pads 33a, 33b on the pixel 100, and the pads 33a, 33b are electrically connected to a circuit on the circuit board 150. For example, the pads 33a, 33b may be electrically connected to the circuit board 150 using bonding wires.

[0253] In this embodiment, the pixel 100 includes three sub-pixels, each of which can emit blue, green and red light, so that each pixel 100 constitutes one pixel, and an image can be realized by using these light-emitting elements 100.

[0254] In the present embodiment, the pixels 100 are arranged on the circuit board 150, but the light emitting devices 200, 300, 400, or 500 may be arranged on the circuit board 150, and various light emitting devices may be mixed and used.

[0255] In addition, depending on the structure of the light emitting cell, the light emitting element can be mounted on the circuit board by using Au-Au bonding or AuSN bonding other than the bonding wire.

[0256] FIG. 21 is a perspective view showing a display device according to one embodiment of the present invention.

[0257] 21, the display device 1000 according to the present invention may include a plurality of modules DM. Each module DM may include a sub-display device 100' and a support 200. The sub-display device 100' may be provided with a plurality of pixels, and each pixel may include a plurality of light emitting diodes as described above. In each light emitting diode, a red light emitting cell that emits red light, a blue light emitting cell that emits blue light, and a green light emitting cell that emits green light may be provided in one pixel. The sub-display device 100' may be provided with a plurality of such light emitting diodes, and the plurality of pixels may be supported by the same support 200.

[0258] The display device 1000 is provided with a plurality of modules DM, allowing the display device 1000 to be made large.

[0259] Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and matters and elements described in one embodiment may be applied to other embodiments without departing from the technical spirit of the present invention.

Claims

1. a first light emitting cell, a second light emitting cell, and a third light emitting cell, each of which includes a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer; pads electrically connected to the first light emitting cells, the second light emitting cells, and the third light emitting cells so as to be independently driven; a second wavelength converter for converting a wavelength of light emitted from the second light emitting cell; a third wavelength converter for converting a wavelength of light emitted from the third light emitting cell, the third wavelength converter converting the wavelength of light to a longer wavelength than the second wavelength converter; The second light emitting cell has a larger area than the first light emitting cell, The third light emitting cell has a larger area than the second light emitting cell.

2. the first light emitting cell, the second light emitting cell, and the third light emitting cell emit blue light; the second wavelength converter converts the blue light to green light; The light-emitting device of claim 1 , wherein the third wavelength converter converts the blue light to red light.

3. The light emitting device of claim 2 , wherein area ratios of the second light emitting cells and the third light emitting cells to the first light emitting cells are inversely proportional to light conversion efficiencies of the second and third wavelength converters, respectively.

4. a first wavelength converter for converting a wavelength of light emitted from the first light emitting cell into light of a first wavelength, the first wavelength converter converting the wavelength of the light into a shorter wavelength than the second wavelength converter; The light emitting device of claim 1 , wherein the first light emitting cell, the second light emitting cell, and the third light emitting cell emit ultraviolet light.

5. the first wavelength converter converts ultraviolet light into blue light; the second wavelength converter converts the ultraviolet light into green light; The light-emitting device of claim 4 , wherein the third wavelength converter converts the ultraviolet light into red light.

6. 6. The light emitting device of claim 5, wherein an area ratio of the second light emitting cell and the third light emitting cell to the first light emitting cell is inversely proportional to an optical conversion efficiency ratio of the second wavelength converter to the first wavelength converter and an optical conversion efficiency ratio of the third wavelength converter to the first wavelength converter, respectively.

7. a first color filter disposed on the first wavelength converter; a second color filter disposed on the second wavelength converter; and The light emitting device of claim 4 , further comprising: a third color filter disposed on the third wavelength converter.

8. a second color filter disposed on the second wavelength converter; and The light emitting device of claim 1 , further comprising: a third color filter disposed on the third wavelength converter.

9. The light emitting device of claim 1 , further comprising a substrate on which the first light emitting cell, the second light emitting cell and the third light emitting cell are disposed.

10. a light shielding barrier provided between each of the first light emitting cells, the second light emitting cells, and the third light emitting cells; The heights of the first light emitting cells to the third light emitting cells are lower than the height of the barrier ribs, The light emitting device of claim 1 , wherein a distance between the barrier wall and the first light emitting cell, the second light emitting cell, or the third light emitting cell is 10 μm to 20 μm.

11. The light emitting device of claim 10 , wherein the barrier ribs provided between the first light emitting cell, the second light emitting cell, and the third light emitting cell are integrally connected to each other.

12. The light emitting device according to claim 10 , wherein the width of the partition increases with increasing distance from the substrate.

13. The light emitting device according to claim 10, wherein a ratio of an area of ​​the partition to a planar area of ​​the substrate is 0.5 to 0.

99.

14. The light emitting device according to claim 10, wherein the partition has a height of 15 to 115 μm.

15. The first light emitting cell emits red light, the second light emitting cell emits green light, and the third light emitting cell emits blue light; The light emitting device of claim 9 , wherein a distance between the first light emitting cell and the second light emitting cell is the same as a distance between the first light emitting cell and the third light emitting cell.

16. The light emitting device of claim 15 , wherein a distance between the first light emitting cell and the second light emitting cell is different from a distance between the second light emitting cell and the third light emitting cell.

17. The first light emitting cell, the second light emitting cell, and the third light emitting cell are provided in one light emitting element, 17. The light emitting device of claim 16, wherein a distance between the first light emitting cell to the third light emitting cell provided in one pixel is shorter than a distance between the first light emitting cell to the third light emitting cell provided in the one pixel and the first light emitting cell to the third light emitting cell provided in a pixel adjacent to the one pixel.

18. The light emitting device of claim 9 , wherein the first light emitting cell, the second light emitting cell, and the third light emitting cell are arranged in a triangular shape.

19. The light emitting device of claim 9 , wherein the first light emitting cell, the second light emitting cell, and the third light emitting cell are arranged in a line shape.

20. The light emitting device of claim 9 , wherein the first light emitting cell, the second light emitting cell, and the third light emitting cell share a first conductive type semiconductor layer.

21. The light emitting device of claim 20 , further comprising an extension portion extending from the pad electrically connected to the shared first conductive type semiconductor layer among the pads.

22. The light-emitting device of claim 1 , wherein the second wavelength converter and the third wavelength converter are located within a same film.

23. the second wavelength converter and the third wavelength converter are located within a laminate film; The light-emitting device of claim 1 , wherein the second wavelength converter and the third wavelength converter are located in different layers.

24. A substrate; a first light emitting cell, a second light emitting cell, and a third light emitting cell provided on the substrate, the first light emitting cell, and the third light emitting cell emitting red light, green light, and blue light; a light shielding barrier provided between each of the first light emitting cells, the second light emitting cells, and the third light emitting cells; The heights of the first light emitting cells to the third light emitting cells are lower than the height of the barrier ribs, a distance between the barrier rib and the first light emitting cell, the second light emitting cell, and the third light emitting cell is equal to or less than 5 μm.

25. A circuit board; a plurality of pixels arranged on the circuit board; A display device, wherein each of the plurality of pixels is a light-emitting element according to claim 1 .

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