Display device

Abstract

According to an aspect of the present application, a display device includes a light emitting element disposed in each of a plurality of sub-pixels, the light emitting element including a first blue light emitting layer, a green light emitting layer on the first blue light emitting layer, and a second blue light emitting layer on the green light emitting layer; a first light conversion layer disposed in a first sub-pixel among the plurality of sub-pixels; and a second light conversion layer disposed in a second sub-pixel among the plurality of sub-pixels and having a higher light conversion efficiency than the first light conversion layer. Accordingly, the second light conversion layer having the higher light conversion efficiency is disposed in the second sub-pixel which is a red sub-pixel, thereby improving the brightness of red light.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0078184, filed on June 26, 2020, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to a display device, and more specifically, to a display device having improved brightness. Background Technology

[0004] Display devices used in computers, TVs, mobile phones, etc., include self-emissive organic light-emitting diode (OLED) display devices and liquid crystal display (LCD) devices that require a separate light source.

[0005] In addition to computer and TV monitors, the application of display devices is gradually diversifying to personal mobile devices, and research has been conducted on display devices with reduced size and weight as well as wider display areas. Summary of the Invention

[0006] One objective of this invention is to provide a display device with improved brightness.

[0007] Another objective of this invention is to provide a display device that improves the efficiency of red and green light emitted from a light-emitting element.

[0008] Another objective of this invention is to provide a display device that allows for easy adjustment of the color temperature of white light.

[0009] The purpose of this invention is not limited to the above-described purposes, and other purposes not mentioned above will be clearly understood by those skilled in the art from the following description.

[0010] According to one aspect of the present invention, a display device includes: a light-emitting element disposed in each of a plurality of sub-pixels, the light-emitting element including a first blue light-emitting layer, a green light-emitting layer on the first blue light-emitting layer, and a second blue light-emitting layer on the green light-emitting layer; a first light conversion layer disposed in a first sub-pixel among the plurality of sub-pixels; and a second light conversion layer disposed in a second sub-pixel among the plurality of sub-pixels and having a higher light conversion efficiency than the first light conversion layer. Therefore, by disposing of the second sub-pixel, which is a red sub-pixel, with a second light conversion layer having a higher light conversion efficiency, the brightness of red light is improved.

[0011] According to another aspect of the present application, a display device includes: a light emitting unit provided in a plurality of sub-pixels including a plurality of white sub-pixels and a plurality of red sub-pixels, the light emitting unit including a light emitting layer emitting blue light and a light emitting layer emitting green; a first light converting layer provided in the plurality of white sub-pixels to convert light emitted from the light emitting unit into red light; and a second light converting layer provided in the plurality of red sub-pixels to convert light emitted from the light emitting unit into red light, wherein a light conversion efficiency of the second light converting layer is higher than a light conversion efficiency of the first light converting layer. Accordingly, in the red sub-pixel, green light and blue light from the light emitting unit are maximally converted into red light, thereby improving the brightness of the display device.

[0012] Further details of exemplary embodiments include those described in the detailed description and drawings.

[0013] According to the present application, the brightness of a display device can be improved by increasing the efficiency of red light and green light in a light emitting element.

[0014] According to the present application, white light having a high color temperature can be displayed by adjusting the ratio of red light and green light emitted from a light emitting element.

[0015] According to the present application, red light and green light having high brightness can be easily realized.

[0016] Effects according to the present application are not limited to what has been described above with respect to the exemplary embodiments, and include more different effects in the present application. BRIEF DESCRIPTION OF DRAWINGS

[0017] The above and other aspects, features, and other advantages of the present application will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is a plan view of a display device according to an exemplary embodiment of the present application;

[0019] Figure 2 is a cross-sectional view taken along line II-II' of Figure 1 ;

[0020] Figure 3 is a view schematically illustrating a structure of a display device according to an exemplary embodiment of the present application;

[0021] Figure 4 is a view schematically illustrating a structure of a display device according to a comparative example;

[0022] Figures 5A to 5D is a graph showing a luminance gradient according to a wavelength in display devices according to a comparative example and an exemplary embodiment.

[0023] Figure 6 FIG. 4 is a diagram schematically illustrating a structure of a display device according to another exemplary embodiment of the present application;

[0024] Figure 7 FIG. 5 is a diagram schematically illustrating a structure of a display device according to still another exemplary embodiment of the present application. DETAILED DESCRIPTION

[0025] Advantages and features of the present application and methods of accomplishing the same can be understood by referring to the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 The present application is not limited to the exemplary embodiments disclosed herein, but is implemented in various forms. The exemplary embodiments are provided by way of example only, so that those skilled in the art can fully understand and appreciate the present application and the scope thereof. Therefore, the present application should be limited only by the scope of the appended claims.

[0026] The shapes, sizes, proportions, angles, numbers, and the like shown in the drawings for describing the exemplary embodiments of the present application are merely examples, and the present application is not limited thereto. Like reference numerals generally refer to like elements throughout the present application. Also, in the following description of the present application, detailed explanations of known related technologies can be omitted to avoid unnecessarily obscuring the subject matter of the present application. The terms such as "include," "have," and the like used herein are generally intended to allow for addition of other components, unless the terms are used with the term "only."

[0027] Components are interpreted to include generally accepted ranges, even if not explicitly stated.

[0028] When a positional relationship between two parts is described using terms such as "on," "above," "below," and "behind," one or more parts can be disposed therebetween, unless the terms are used with the term "immediately" or "directly."

[0029] When an element or a layer is "on" another element or layer, it can be directly on the other element or layer, or one or more intervening layers or elements can be interposed therebetween.

[0030] Although various components are described using the terms "first," "second," and the like, the components are not limited by the terms. The terms are used only to distinguish one component from another component. Therefore, the first component mentioned below can be the second component within the technical idea of the present application.

[0031] The same reference numerals are generally used to designate the same elements throughout the present application.

[0032] The size and thickness of each component shown in the drawings are shown for convenience of description only, and the present application is not limited to the size and thickness of the components shown in the drawings.

[0033] Features of the embodiments of the present application can be combined or integrated with each other in part or in whole, and features of the embodiments can be technically associated and operated with each other in various ways, and the embodiments can be independently implemented from each other or in association with each other.

[0034] Hereinafter, a display device according to an exemplary embodiment of the present application will be described in detail with reference to the accompanying drawings.

[0035] Figure 1 is a plan view of a display device according to an exemplary embodiment of the present application. In Figure 1 In the drawing, only the substrate 110 and the plurality of sub-pixels SP among the components of the display device 100 are shown for convenience of description.

[0036] The substrate 110 can be a support member for supporting other components of the display device 100, and can be made of an insulating material. For example, the substrate 110 can be made of glass, resin, or the like. In addition, the substrate 110 can be made of plastic such as a polymer or polyimide (PI), or can be made of a material having flexibility.

[0037] The substrate 110 includes a display area AA and a non-display area NA. The display area AA is an area in which an image is displayed. In the display area AA, a plurality of sub-pixels SP for displaying an image and a driving circuit for driving the plurality of sub-pixels SP can be provided. The driving circuit can include various thin film transistors, storage capacitors, lines, etc. for driving the sub-pixels SP. For example, the driving circuit can be constituted by various components such as a driving transistor, a switching transistor, a storage capacitor, a scan line, and a data line, but is not limited thereto.

[0038] The non-display area NA is an area in which an image is not displayed, and is an area in which various lines, driving ICs, etc. are provided to drive the sub-pixels SP provided in the display area AA. For example, various driving ICs such as a gate driver IC and a data driver IC can be provided in the non-display area NA.

[0039] Meanwhile, in Figure 2 The non-display area NA is shown as surrounding the display area AA, but can be an area extending from any side of the display area AA, but is not limited thereto.

[0040] The display area AA contains multiple sub-pixels SP. Each of the multiple sub-pixels SP is a separate unit for emitting light, and each of the multiple sub-pixels SP contains a light-emitting element and a driving circuit. For example, the multiple sub-pixels SP may include red sub-pixels, green sub-pixels, blue sub-pixels, and white sub-pixels, but is not limited to these.

[0041] In the following text, reference will be made to Figure 2 A more detailed description of multiple sub-pixels SP.

[0042] Figure 1 It is along Figure 2 The cross-sectional view taken from line II-II'. (Refer to...) Figure 2 According to an exemplary embodiment of the present invention, the display device 100 includes a substrate 110, a buffer layer 111, a gate insulating layer 112, a protective layer 113, a planarization layer 114, a dam 115, a transistor 120, a light-emitting element 130, a light conversion layer CCL, and a color filter CF.

[0043] First, the multiple sub-pixels SP include a first sub-pixel SP1, a second sub-pixel SP2, a third sub-pixel SP3, and a fourth sub-pixel SP4. Each of these sub-pixels can emit light of a different color. For example, each of these sub-pixels can be a white sub-pixel emitting white light, a red sub-pixel emitting red light, a green sub-pixel emitting green light, and a blue sub-pixel emitting blue light, respectively. In the following description, we will assume that the first sub-pixel SP1 is a white sub-pixel, the second sub-pixel SP2 is a red sub-pixel, the third sub-pixel SP3 is a green sub-pixel, and the fourth sub-pixel SP4 is a blue sub-pixel, but this is not a limitation.

[0044] A buffer layer 111 is provided on the substrate 110. The buffer layer 111 can minimize the permeation and diffusion of moisture and / or oxygen from the outside of the substrate 110 into the display device 100. The buffer layer 111 may be made of an inorganic material, for example, the buffer layer 111 may be composed of a single layer or multiple layers of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

[0045] A plurality of transistors 120 is provided over the buffer layer 111. Each of the plurality of transistors 120 can be provided in each of the plurality of sub-pixels SP. The transistor 120 provided in each of the plurality of sub-pixels SP can function as a driving element of the display device 100. The transistor 120 can be, for example, a thin film transistor (TFT), an N-channel metal oxide semiconductor (NMOS) transistor, a P-channel metal oxide semiconductor (PMOS) transistor, a complementary metal oxide semiconductor (CMOS) transistor, a field effect transistor (FET), or the like, but is not limited thereto. Hereinafter, the description will be made assuming that the plurality of transistors 120 is a thin film transistor, but is not limited thereto.

[0046] The transistor 120 includes a gate electrode 121, an active layer 122, a source electrode 123, and a drain electrode 124.

[0047] The gate electrode 121 of the transistor 120 is provided over the buffer layer 111. The gate electrode 121 can be made of a conductive material, for example, copper (Cu), aluminum (Al), molybdenum (Mo), titanium (Ti), or an alloy thereof, but is not limited thereto.

[0048] The gate insulating layer 112 is provided over the gate electrode 121. The gate insulating layer 112 is a layer for insulating the gate electrode 121 and the active layer 122. The gate insulating layer 112 can be made of an inorganic material, for example, the gate insulating layer 112 can be composed of a single layer or a plurality of layers of silicon oxide (SiOx) or silicon nitride (SiNx), but is not limited thereto.

[0049] The active layer 122 is provided over the gate insulating layer 112. The active layer 122 can be made of an oxide semiconductor, amorphous silicon, or polycrystalline silicon, or the like, but is not limited thereto.

[0050] The source electrode 123 and the drain electrode 124 are provided over the active layer 122 so as to be separated from each other. The source electrode 123 and the drain electrode 124 are in contact with the active layer 122, and thus are electrically connected to the active layer 122. The source electrode 123 and the drain electrode 124 can be made of a conductive material, for example, titanium (Ti), copper (Cu), aluminum (Al), molybdenum (Mo), or an alloy thereof, but are not limited thereto.

[0051] Meanwhile, in Figure 3 the transistor 120 is illustrated as a bottom gate structure in which the active layer 122 is provided over the gate electrode 121, but is not limited thereto, and can be implemented as a different structure such as a top gate structure.

[0052] A protective layer 113 is provided on the transistor 120. The protective layer 113 is an insulating layer that protects the transistor 120. The protective layer 113 can be composed of a single layer of silicon nitride (SiNx) or silicon oxide (SiOx) as an inorganic material, or multiple layers of silicon nitride (SiNx) and silicon oxide (SiOx), but is not limited thereto. However, the protective layer 113 can be omitted according to the design of the display device 100.

[0053] Meanwhile, the display device 100 can be implemented as a top emission type display device or a bottom emission type display device. The top emission type is a type in which light emitted from the light emitting element 130 is emitted toward the top of the light emitting element 130 to implement an image on the top of the substrate 110. The bottom emission type is a type in which light emitted from the light emitting element 130 is emitted toward the bottom of the light emitting element 130 to implement an image on the bottom of the substrate 110. Further, the display device 100 can be implemented as a double-sided emission type in which light emitted from the light emitting element 130 is emitted toward the top and the bottom of the light emitting element 130 to implement an image on both surfaces of the substrate 110. Hereinafter, the display device 100 is described as a bottom emission type, but is not limited thereto.

[0054] A plurality of color filters CF is provided on the protective layer 113. The plurality of color filters CF can convert light emitted from the light emitting element 130 into various colors. Specifically, the plurality of color filters CF transmits only light having a specific wavelength range among light emitted from the light emitting element 130, and absorbs the remaining light, thereby converting the color of light emitted to the outside of the display device 100.

[0055] The plurality of color filters CF includes a red color filter CFR, a green color filter CFG, and a blue color filter CFB. The red color filter CFR can be provided in the second sub-pixel SP2 that is a red sub-pixel, the green color filter CFG can be provided in the third sub-pixel SP3 that is a green sub-pixel, and the blue color filter CFB can be provided in the fourth sub-pixel SP4 that is a blue sub-pixel.

[0056] A light conversion layer CCL is provided on some of the plurality of sub-pixels SP. The light conversion layer CCL can be provided in the first sub-pixel SP1 that is a white sub-pixel and the second sub-pixel SP2 that is a red sub-pixel among the plurality of sub-pixels SP. The light conversion layer CCL can convert light emitted from the light emitting element 130 into various colors. Specifically, the light conversion layer CCL can convert the color of light by absorbing light emitted from the light emitting element 130 to emit light having a specific wavelength.

[0057] The light conversion layer CCL includes a first light conversion layer CCL1 and a second light conversion layer CCL2. The first light conversion layer CCL1 is provided on the protective layer 113 in the first sub-pixel SP1, and the second light conversion layer CCL2 is provided on the red color filter CFR in the second sub-pixel SP2, that is, the red color filter CFR can overlap the second light conversion layer CCL2. The first light conversion layer CCL1 and the second light conversion layer CCL2 can convert the light emitted from the light emitting element 130 into light having the same color. For example, the first light conversion layer CCL1 and the second light conversion layer CCL2 can be light conversion layers CCL that convert the light emitted from the light emitting element 130 into red light, which will be described below with reference to FIG. 2. Figure 3 A more detailed description will be described.

[0058] Each of the first light conversion layer CCL1 and the second light conversion layer CCL2 includes a base member and a light conversion material.

[0059] The base member is a transparent member for supporting the light conversion material, and can be made of a transparent photoresist, an acrylic material such as polymethyl methacrylate (PMMA), or a transparent material such as a silicone resin such as polydimethylsiloxane (PDMS) or an epoxy resin, but is not limited thereto.

[0060] The light conversion material is a material that is distributed in the base member and absorbs the light emitted from the light emitting element 130 to convert the light into light of a different color. The light conversion material can be made of, for example, a nanophosphor, an organic phosphor, a quantum dot, a fluorescent dye, or the like, but is not limited thereto.

[0061] For example, when the light conversion material is made of a fluorescent dye, the light conversion material can be made of a material that converts green light and blue light into red light, such as Ph9 (9-diethylamino-5H-benzo[a]phenoxazin-5-one) or Ph9S (9-diphenylamino-5H-benzo[a]phenoxazin-5-one), but is not limited thereto.

[0062] For example, when the light conversion material is made of a quantum dot, the light conversion material can be made of a quantum dot material that converts green light and blue light into red light, such as InAs, InP, or PbS, but is not limited thereto.

[0063] The thickness of the first light conversion layer CCL1 can be smaller than the thickness of the second light conversion layer CCL2. When the first light conversion layer CCL1 has a smaller thickness than the second light conversion layer CCL2, the light conversion efficiency in the first light conversion layer CCL1 can be lower than the light conversion efficiency in the second light conversion layer CCL2. Specifically, when the first light conversion layer CCL1 and the second light conversion layer CCL2 are formed by using a base member in which a light conversion material is distributed at the same concentration, as the thickness of the light conversion layer CCL increases, the amount of the light conversion material included in the light conversion layer CCL can increase. Therefore, since the thickness of the second light conversion layer CCL2 is greater than the thickness of the first light conversion layer CCL1, the light conversion efficiency in the second light conversion layer CCL2 can be higher than the light conversion efficiency in the first light conversion layer CCL1.

[0064] Further, in order to control the light conversion efficiency of the first light conversion layer CCL1 and the second light conversion layer CCL2, the type or concentration of the light conversion material included in each of the first light conversion layer CCL1 and the second light conversion layer CCL2 can be differently configured. For example, in order to reduce the efficiency of the first light conversion layer CCL1, a light conversion material having a relatively low light conversion efficiency can also be used, and the concentration of the light conversion material of the first light conversion layer CCL1 can also be reduced.

[0065] In a cross-section, the width of the second light conversion layer CCL2 can be smaller than or equal to the width of the red color filter CFR. In a plane, the size (or area) of the second light conversion layer CCL2 can be smaller than or equal to the size of the red color filter CFR. That is, the size of the lower surface of the second light conversion layer CCL2, which is in contact with the red color filter CFR, can be smaller than or equal to the size of the upper surface of the red color filter CFR. Further, the entire lower surface of the second light conversion layer CCL2 can be in contact with only the upper surface of the red color filter CFR.

[0066] If the second light conversion layer CCL2 protrudes outside the red color filter CFR, color mixing occurs by the second light conversion layer CCL2 protruding from the first sub-pixel SP1 and / or the third sub-pixel SP3 adjacent to the second sub-pixel SP2, such that the display quality can be degraded. For example, when the second light conversion layer CCL2 protrudes outside the red color filter CFR and extends to the first sub-pixel SP1, the purity of the white light displayed in the first sub-pixel SP1 can be degraded. Similarly, when the second light conversion layer CCL2 extends to the third sub-pixel SP3, the purity of the green light displayed in the third sub-pixel SP3 can be degraded. Therefore, the entire lower surface of the second light conversion layer CCL2 is disposed to be in contact with only the upper surface of the red color filter CFR, thereby minimizing the color mixing problem between the plurality of sub-pixels SP.

[0067] A planarization layer 114 is provided on the first light conversion layer CCL1 and the second light conversion layer CCL2. The planarization layer 114 can planarize the top of the substrate 110. The planarization layer 114 can be composed of a single layer or multiple layers, and can be made of an organic material. For example, the planarization layer 114 can be made of an acrylic organic material, but is not limited thereto.

[0068] A light emitting element 130 is provided on the planarization layer 114. The light emitting element 130 is an element for emitting light, and can be provided in each of the plurality of sub-pixels SP to be driven by the plurality of transistors 120. The light emitting element 130 can include an anode 131, a light emitting unit 132, and a cathode 133.

[0069] The anode 131 can supply holes to the light emitting unit 132, and can be made of a conductive material having a high work function. For example, the anode 131 can be made of indium oxide (IO), indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (ITZO), or the like, but is not limited thereto.

[0070] A bank 115 is provided on the anode 131. The bank 115 can be provided to cover the edges of the anode 131. The bank 115 can be provided at the boundaries between the plurality of sub-pixels SP to define the plurality of sub-pixels SP. The bank 115 can be made of an insulating material, for example, polyimide, acryl, or benzocyclobutene (BCB)-based resin, but is not limited thereto.

[0071] The light emitting unit 132 is provided on the anode 131 and the bank 115. The light emitting unit 132 can receive holes from the anode 131 and receive electrons from the cathode 133, thereby emitting light. The light emitting unit 132 can be formed by laminating a plurality of stacks including one or more light emitting layers. For example, the light emitting unit 132 can include organic layers including a plurality of stacks such as a light emitting layer, a hole transport layer, an electron transport layer, an electron injection layer, and a hole injection layer, and a charge generation layer provided between the plurality of stacks.

[0072] The cathode 133 is provided on the light emitting unit 132. The cathode 133 can supply electrons to the light emitting unit 132, and can be made of a conductive material having a low work function. For example, the cathode 133 can be made of at least one selected from the group consisting of metals such as magnesium (Mg), silver (Ag), aluminum (Al), and calcium (Ca), and alloys thereof, but is not limited thereto.

[0073] At this time, in order to guide light emitted from the light emitting unit 132 to the bottom of the substrate 110, the anode 131 can be made of only a transparent conductive material, and the cathode 133 can be made of a metal material having a high reflectivity.

[0074] Hereinafter, a description will be given with reference to Figure 3A light emitting element 130 according to an example embodiment of the present application will be described in detail.

[0075] Figure 3 FIG. 1 is a schematic diagram illustrating a structure of a display device according to an example embodiment of the present application. In Figure 3 In FIG. 1, for convenience of description, only the light emitting layers 132B1, 132G, and 132B2 in each configuration of the plurality of stacks ST1, ST2, and ST3 of the light emitting unit 132 are illustrated.

[0076] Referring to Figure 4 The light emitting unit 132 includes a first stack ST1 including a first blue light emitting layer 132B1, a second stack ST2 including a green light emitting layer 132G, and a third stack ST3 including a second blue light emitting layer 132B2. Light finally emitted from the light emitting unit 132 can be realized by mixing light respectively emitted by the first blue light emitting layer 132B1, the green light emitting layer 132G, and the second blue light emitting layer 132B2 of the plurality of stacks ST1, ST2, and ST3. Thus, light emitted from the light emitting unit 132 can include blue light and green light.

[0077] The first stack ST1 including the first blue light emitting layer 132B1 is disposed on the anode 131. The first blue light emitting layer 132B1 of the first stack ST1 can emit blue light by holes and electrons provided from the anode 131 and the cathode 133. The first blue light emitting layer 132B1 can include a material capable of emitting blue light. In addition, although not illustrated in the drawing, the first stack ST1 can further include organic layers such as a hole transport layer, an electron transport layer, an electron injection layer, and a hole injection layer, in addition to the first blue light emitting layer 132B1.

[0078] The second stack ST2 including the green light emitting layer 132G is disposed on the first stack ST1. The green light emitting layer 132G of the second stack ST2 can emit green light by holes and electrons provided from the anode 131 and the cathode 133. The green light emitting layer 132G can include a material capable of emitting green light. In addition, although not illustrated in the drawing, the second stack ST2 can further include organic layers such as a hole transport layer, an electron transport layer, an electron injection layer, and a hole injection layer, in addition to the green light emitting layer 132G.

[0079] A third stack ST3 including a second blue light emitting layer 132B2 is disposed on the second stack ST2. The second blue light emitting layer 132B2 can emit blue light in the same manner as the first blue light emitting layer 132B1. Also, the second blue light emitting layer 132B2 can include a material capable of emitting blue light. Also, although not shown in the drawing, the third stack ST3 can further include organic layers such as a hole transport layer, an electron transport layer, an electron injection layer, and a hole injection layer, in addition to the second blue light emitting layer 132B2.

[0080] Also, although not shown in the drawing, a charge generation layer can be disposed between the first stack ST1, the second stack ST2, and the third stack ST3, respectively. The charge generation layer can provide charges to the adjacent stacks ST1, ST2, and ST3 to control charge balance.

[0081] Meanwhile, since the display device 100 according to the exemplary embodiment of the present application is a bottom emission type, light emitted from the light emitting unit 132 propagates toward the substrate 100. Also, the light emitted from the light emitting unit 132 can pass through the plurality of color filters CF and the plurality of light conversion layers CCL, thereby being converted into light of various colors.

[0082] First, blue light and green light from the light emitting unit 132 of the third sub-pixel SP3 can be realized as green light by the green color filter CFG. Specifically, the blue light among the blue light and the green light is absorbed in the green color filter CFG, and only the green light can pass through the green color filter CFG to propagate toward the substrate 110. Thus, light emitted from the light emitting unit 132 of the third sub-pixel SP3 can be realized as green light by the green color filter CFG.

[0083] Blue light and green light from the light emitting unit 132 of the fourth sub-pixel SP4 can be realized as blue light by the blue color filter CFB. Specifically, the green light among the blue light and the green light is absorbed in the blue color filter CFB, and only the blue light can pass through the blue color filter CFB to propagate toward the substrate 110. Thus, light emitted from the light emitting unit 132 of the fourth sub-pixel SP4 can be realized as blue light by the blue color filter CFB.

[0084] The blue light and the green light from the light emitting unit 132 of the first sub-pixel SP1 can be implemented as white light by the first light conversion layer CCL1. Unlike a color filter CF that converts the color of light by transmitting only light having a specific wavelength, in the case of the first light conversion layer CCL1, a light conversion material absorbs light to re-emit light of a specific color, thereby converting the color of light. Accordingly, when the blue light and the green light are irradiated to the first light conversion layer CCL1 from the light emitting unit 132, the light conversion material of the first light conversion layer CCL1 can absorb at least some of the blue light and the green light, and the light conversion material that has absorbed the light can emit red light. Also, some of the blue light and the green light can pass through the first light conversion layer CCL1 without being absorbed in the light conversion material. Some of the blue light and some of the green light that have passed through the first light conversion layer CCL1 are mixed with the red light emitted from the light conversion material, thereby finally implementing white light. Accordingly, in the first sub-pixel SP1, the first light conversion layer CCL1 that absorbs at least some of the blue light and the green light to emit red light can be provided to implement white light.

[0085] The blue light and the green light from the light emitting unit 132 of the second sub-pixel SP2 can be implemented as red light by the second light conversion layer CCL2 and the red color filter CFR. Like the first light conversion layer CCL1, the second light conversion layer CCL2 can also absorb light to emit red light. Specifically, the blue light and the green light from the light emitting unit 132 can face the second light conversion layer CCL2 and the light conversion material of the second light conversion layer CCL2 can absorb at least some of the blue light and the green light and then emit red light. Accordingly, some of the blue light and the green light from the light emitting unit 132 can be converted to red light in the second light conversion layer CCL2. Some of the blue light, some of the green light, and the red light that have passed through the second light conversion layer CCL2 can face the red color filter CFR. Also, among the blue light and the green light from the second light conversion layer CCL2, the blue light and the green light are absorbed in the red color filter CFR, and only the red light can be propagated toward the substrate 110. Accordingly, in the second sub-pixel SP2, the second light conversion layer CCL2 that absorbs the blue light and the green light to emit red light and the red color filter CFR that transmits only the red light can be provided to implement red light.

[0086] At this time, in the second sub-pixel SP2, the second light conversion layer CCL2 can be disposed closer to the light emitting element 130 than the red color filter CFR. If the red color filter CFR is disposed closer to the light emitting element 130, the blue light and the green light from the light emitting element 130 are absorbed in the red color filter CFR, so that the light propagating toward the second light conversion layer CCL2 is minimized. That is, if the red color filter CFR is disposed closer to the light emitting element 130 than the second light conversion layer CCL2, the light emitted from the light emitting element 130 is almost absorbed in the red color filter CFR without propagating outside the display apparatus 100, so that it is difficult to display an image. Therefore, the second light conversion layer CCL2 for absorbing light to emit red light needs to be disposed closer to the light emitting element 130 than the red color filter CFR, thereby realizing red light.

[0087] In the display apparatus 100 according to the exemplary embodiment of the present application, the first light conversion layer CCL1 of the first sub-pixel SP1 and the second light conversion layer CCL2 of the second sub-pixel SP2 are designed to have different thicknesses to realize white light having a high color temperature and red light having a high luminance. First, the first light conversion layer CCL1 is formed to have a thin thickness to easily realize white light having a high color temperature. As a method of expressing the color of light as a value, the color temperature can be expressed by using a color temperature unit, K (Kelvin). A light source based on red has a lower color temperature, and a light source based on blue has a higher color temperature. At this time, the light conversion efficiency of the first light conversion layer CCL1 can be adjusted to display white light having a high color temperature in the first sub-pixel SP1. For example, in order to realize blue-based white light having a high color temperature, it is necessary to reduce the ratio of converting blue light and green light into red light in the first light conversion layer CCL1. Therefore, the thickness of the first light conversion layer CCL1 is smaller than the thickness of the second light conversion layer CCL2 to convert at least only red light from blue light and green light to realize white light. Therefore, the blue light and the green light from the light emitting unit 132 are mixed with the red light emitted from the first light conversion layer CCL1, thereby displaying blue-based white, i.e., white light having a high color temperature.

[0088] In the display device 100 according to the exemplary embodiment of the present application, in the second sub-pixel SP2 that is a red sub-pixel displaying red light, the thickness of the second light conversion layer CCL2 is increased, thereby realizing red light with high luminance. Since the light emitting unit 132 includes only the first blue light emitting layer 132B1, the green light emitting layer 132G, and the second blue light emitting layer 132B2, only blue light and green light can be emitted from the light emitting unit 132. Further, in order to realize red light with high luminance based on such blue light and green light, it is necessary to increase the ratio of conversion of the blue light and the green light into red light. Thus, the thickness of the second light conversion layer CCL2 is increased, thereby increasing the ratio of conversion of the blue light and the green light passing through the second light conversion layer CCL2 into red light in the light conversion material. Therefore, since the second light conversion layer CCL2 is formed to be thicker than the first light conversion layer CCL1, the light conversion efficiency of the second light conversion layer CCL2 for converting the blue light and the green light into red light can be higher than the light conversion efficiency of the first light conversion layer CCL1.

[0089] On the other hand, in the display device 100 according to the exemplary embodiment of the present application, the light emitting unit 132 emitting blue light and green light, the first light conversion layer CCL1 and the second light conversion layer CCL2 having different light conversion efficiencies, and the plurality of color filters CF can be used together to improve the luminance of the display device 100. Hereinafter, the luminance improvement effect of the light emitting element of the display device 100 according to the exemplary embodiment of the present application will be described together with Figures 5A-5D and Figure 4 the luminance improvement effect of the display device 100 according to the exemplary embodiment of the present application will be described together with

[0090] Figures 5A to 5D is a view schematically illustrating the structure of a display device according to a comparative example. Figure 5A is a graph showing the luminance change rate according to the wavelength in the display devices according to the comparative example and the exemplary embodiment. Figure 5B is a graph showing the luminance change rate according to the wavelength in the first sub-pixels SP1 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment. Figure 5C is a graph showing the luminance change rate according to the wavelength in the second sub-pixels SP2 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment. Figure 5D is a graph showing the luminance change rate according to the wavelength in the third sub-pixels SP3 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment. Figures 5A to 5D is a graph showing the luminance change rate according to the wavelength in the fourth sub-pixels SP4 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment.

[0091] In Figures 5A to 5DIn this diagram, the horizontal axis represents wavelength (nm), and the vertical axis represents relative intensity (au, i.e., any unit). Figures 1 to 3 In this context, the graph is a graph measuring the light ultimately realized in each of the plurality of sub-pixels SP of the display devices 10 and 100 according to the comparative example and exemplary embodiments.

[0092] The display device 100 and reference according to the exemplary embodiment Figure 4 The display device 100 described is the same as that described in the exemplary embodiment of the present invention.

[0093] In addition, refer to Figure 4 When the display device 10 according to the comparative example is compared with the display device 100 according to the exemplary embodiment of the present invention, the light-emitting unit 32 is different in the structure of the display device 10 and does not include the light conversion layer.

[0094] In the display device 10 according to the comparative example, transistors 12, a plurality of color filters CF and a planarization layer 14 are sequentially disposed on a substrate 11, and light-emitting units 32 are disposed on the planarization layer 14.

[0095] The light-emitting unit 32 includes a first stack ST1, a second stack ST2, and a third stack ST3. The first stack ST1 includes a first blue light-emitting layer 32B1, the second stack ST2 on the first stack ST1 includes a red light-emitting layer 32R and a green light-emitting layer 32G, and the third stack ST3 on the second stack ST2 includes a second blue light-emitting layer 32B2. Therefore, the light ultimately emitted from the light-emitting unit 32 of the display device 10 according to the comparative example can be achieved by mixing red and green light from the red light-emitting layer 32R and the green light-emitting layer 32G with blue light from the first blue light-emitting layer 32B1 and the second blue light-emitting layer 32B2. For example, the light emitted from the light-emitting unit 32 can be white light, a mixture of blue, red, and green light. Meanwhile, in Figures 5A to 5D The diagram shows that in the second stack ST2, a green light-emitting layer 32G is disposed on a red light-emitting layer 32R, but it is not limited thereto; the red light-emitting layer 32R may also be disposed on a green light-emitting layer 32G.

[0096] Further, a light conversion layer CCL is not provided between the light emitting element 30 and the substrate 11, but only a plurality of color filters CF are provided. In the first sub-pixel SP1, no color filter CF and / or light conversion layer is provided, and thus white light emitted from the light emitting unit 32 can be displayed. In the second sub-pixel SP2, a red color filter CFR for transmitting only red light among the white light from the light emitting unit 32 is provided, to display red light. In the third sub-pixel SP3, a green color filter CFG for transmitting only green light among the white light from the light emitting unit 32 is provided, to display green light. In the fourth sub-pixel SP4, a blue color filter CFB for transmitting only blue light among the white light from the light emitting unit 32 is provided, to display blue light.

[0097] Table 1 is a table shown by measuring the luminance of light emitted from each of the plurality of sub-pixels SP in the display device 10 according to the comparative example and the display device 100 according to the exemplary embodiment, based on a graph of Comparative Example

[0098] [Table 1]

[0099] Exemplary Embodiments Luminance of the first sub-pixel SP1 190 nit 232 nit Luminance of the second sub-pixel SP2 171 nit 266 nit Luminance of the third sub-pixel SP3 191 nit 422 nit Luminance of the fourth sub-pixel SP4 272 nit 288 nit Figures 5A to 5D

[0100] Hereinafter, referring to Figure 5A and Table 1, the measurement results of the luminance of light emitted from each of the plurality of sub-pixels SP in the display device 10 according to the comparative example and the display device 100 according to the exemplary embodiment will be described.

[0101] First, referring to Table 1, it can be confirmed that the luminance of the final product is 232 nit in the display device 100 according to the exemplary embodiment, and the luminance of the final product is 171 nit in the display device 10 according to the comparative example, and as a result, the luminance of the display device 100 according to the exemplary embodiment is increased compared to the display device 10 according to the comparative example. At this time, the luminance of the final product can be defined as the lowest luminance among the luminances of each of the plurality of sub-pixels SP.

[0102] Referring to Figure 5A , the wavelength of light emitted from the first sub-pixel SP1 of the display device 10 according to the comparative example can have peaks at about 470 nm, 530 nm, and 630 nm. Further, the wavelength of light emitted from the first sub-pixel SP1 of the display device 100 according to the exemplary embodiment can have peaks at about 470 nm, 530 nm, and 630 nm. As a result, the wavelength of light emitted from the first sub-pixel SP1 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment, respectively, has peaks at 470 nm corresponding to the wavelength range of blue light, 530 nm corresponding to the wavelength range of green light, and 630 nm corresponding to the wavelength range of red light, thereby becoming white light.​

[0103] At this time, in the display device 10 according to the comparative example, since red light and green light are emitted from the red light emitting layer 32R and the green light emitting layer 32G of one second stack ST2, the red light and the green light can have a trade-off relationship. When the red light emitting layer 32R and the green light emitting layer 32G are provided together in one second stack ST2, the performance of the red light emitting layer 32R and the performance of the green light emitting layer 32G can have a trade-off relationship. For example, when the luminance of the red light emitting layer 32R is improved, the luminance of the green light emitting layer 32G can decrease; and when the luminance of the green light emitting layer 32G is improved, the luminance of the red light emitting layer 32R can decrease. Thus, when the red light emitting layer 32R and the green light emitting layer 32G are provided together in the second stack ST2, it is difficult to ensure the luminance of the green light having a peak at about 530 nm or the luminance of the red light having a peak at about 630 nm at a predetermined level or more. On the other hand, in the display device 100 according to the exemplary embodiment, since only one green light emitting layer 132G is provided in the second stack ST2, the limitation due to the trade-off relationship can be overcome and the luminance of the green light having a peak at about 530 nm can be improved. Therefore, in the graph of FIG. 6, the display device 100 according to the exemplary embodiment can have a higher intensity than the display device 10 according to the comparative example near about 530 nm corresponding to the green light. Figure 5A

[0104] Further, in the display device 100 according to the exemplary embodiment, since some of the blue light and the green light are converted into red light by the first light conversion layer CCL1, the light conversion efficiency of the first light conversion layer CCL1 can be adjusted to control the luminance, i.e., the intensity, of the red light. On the other hand, in the display device 10 according to the comparative example, since no light conversion layer is provided in the first sub-pixel SP1, white light can be realized only by the light emitted from the light emitting unit 32. Further, as described above, in the display device 10 according to the comparative example, since the red light emitting layer 32R and the green light emitting layer 32G provided together in one second stack ST2 have a trade-off relationship, the luminance of the green light can decrease by increasing the luminance of the red light. That is, unlike the display device 100 according to the exemplary embodiment capable of easily ensuring the red light by the first light conversion layer CCL1, in the display device 10 according to the comparative example, the red light depends only on the red light emitting layer 32R. Further, in the display device 10 according to the comparative example, due to the trade-off relationship between the red light emitting layer 32R and the green light emitting layer 32G, there is a limitation in emitting the red light at a predetermined level or more in the red light emitting layer 32R, and it can be difficult to ensure sufficient red light. Therefore, in the graph of FIG. 6, the display device 10 according to the comparative example can have a lower intensity than the display device 100 according to the exemplary embodiment near about 630 nm corresponding to the red light. Figure 5B ​In the graph, the display device 100 according to the exemplary embodiment can have a higher intensity than the display device 10 according to the comparative example near about 630 nm corresponding to red light. Thus, the first sub-pixel SP1 of the display device 100 according to the exemplary embodiment realizes red light and green light with a higher intensity than the first sub-pixel SP1 of the display device 10 according to the comparative example, thereby finally ensuring white light having a higher brightness.

[0105] Next, referring to FIG. 6, the display device 100 according to the exemplary embodiment will be described in detail. Figure 5C The wavelength of light emitted from the second sub-pixel SP2 of the display device 10 according to the comparative example can have a peak at about 630 nm. Also, the wavelength of light emitted from the second sub-pixel SP2 of the display device 100 according to the exemplary embodiment can also have a peak at about 630 nm. Thus, each wavelength of light emitted from the second sub-pixels SP2 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment can also have a peak at about 630 nm, thereby becoming red light.

[0106] Referring to Table 1 together, the brightness of light emitted from the second sub-pixel SP2 of the display device 10 according to the comparative example is 171 nit, and the brightness of light emitted from the second sub-pixel SP2 of the display device 100 according to the exemplary embodiment is 266 nit. Thus, the brightness of the second sub-pixel SP2 in the display device 100 according to the exemplary embodiment can be higher than the brightness of the second sub-pixel SP2 in the display device 10 according to the comparative example.

[0107] Specifically, in the display device 100 according to the exemplary embodiment, some of the blue light and green light emitted from the light emitting unit 132 are converted into red light in the second light conversion layer CCL2. The red light converted by the second light conversion layer CCL2 passes through the red color filter CFR and the unconverted blue light and green light are absorbed by the red color filter CFR, and can be realized as red light having a higher purity. In the display device 100 according to the exemplary embodiment, the blue light and green light emitted from the light emitting unit 132 are maximally converted into red light, thereby minimizing light loss in the red color filter CFR.

[0108] On the other hand, in the display device 10 according to the comparative example, since only the red color filter CFR is provided in the second sub-pixel SP2, only the red light among the blue light, the green light, and the red light emitted from the light emitting unit 32 passes through the red color filter CFR, and the blue light and the green light are absorbed in the red color filter CFR without propagating to the outside of the display device 10. That is, the luminance of the second sub-pixel SP2 of the display device 10 according to the comparative example can be determined only by the red light emitted from the red light emitting layer 32R of the second stack ST2 of the light emitting unit 32. In the display device 10 according to the comparative example, the blue light and the green light are not emitted to the outside of the display device due to the red color filter CFR. However, in the display device 100 according to the exemplary embodiment, the blue light and the green light are converted into the red light, thereby passing through the red color filter CFR, so that the luminance of the second sub-pixel SP2 can be further improved in the display device 100 according to the exemplary embodiment. Therefore, in the display device 10 according to the comparative example, the blue light and the green light are lost in the red color filter CFR of the second sub-pixel SP2. However, in the display device 100 according to the exemplary embodiment, the blue light and the green light are converted into the red light and emitted, thereby reducing the light loss in the red color filter CFR and improving the luminance of the red light.

[0109] Referring to Figure 5B The wavelength of the light emitted from the third sub-pixel SP3 of the display device 10 according to the comparative example can have a peak at about 530 nm. Also, the wavelength of the light emitted from the third sub-pixel SP3 of the display device 100 according to the exemplary embodiment can also have a peak at about 530 nm. Therefore, each wavelength of the light emitted from the third sub-pixel SP3 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment can also have a peak at about 650 nm, thereby becoming green light.

[0110] Referring to Table 1 together, the luminance of the light emitted from the third sub-pixel SP3 of the display device 10 according to the comparative example is 191 nit, and the luminance of the light emitted from the third sub-pixel SP3 of the display device 100 according to the exemplary embodiment is 422 nit. That is, the luminance of the third sub-pixel SP3 in the display device 100 according to the exemplary embodiment can be higher than the luminance of the third sub-pixel SP3 in the display device 10 according to the comparative example.

[0111] Specifically, the red light emitting layer 32R and the green light emitting layer 32G are provided together in the second stack ST2 of the light emitting unit 32 of the display device 10 according to the comparative example. Further, the red light emitting layer 32R and the green light emitting layer 32G provided together in one second stack ST2 can have a trade-off relationship. Due to this trade-off relationship, in a case where the luminance of the red light emitted from one second stack ST2 is increased, the luminance of the green light can decrease, and in a case where the luminance of the green light is increased, the luminance of the red light can decrease. As a result, the display device 10 according to the comparative example is a structure in which the light emitting unit 32 provided in each of the plurality of sub-pixels SP is integrally formed, and in the display device 10, in a case where the luminance of the second sub-pixel SP2 is increased, the luminance of the third sub-pixel SP3 which emits green light can decrease. Further, in a case where the luminance of the third sub-pixel SP3 is increased, the luminance of the second sub-pixel SP2 can decrease. Therefore, in the display device 10 according to the comparative example, the red light and the green light are implemented by one second stack ST2, so that it is difficult to implement the luminance of the light emitted from the second sub-pixel SP2 and the third sub-pixel SP3 at a predetermined level or higher.

[0112] On the other hand, in the display device 100 according to the exemplary embodiment, the light emitting unit 132 emits only the green light and the blue light and implements the red light by the second light conversion layer CCL2 and the red color filter CFR, thereby separately controlling the luminance of the second sub-pixel SP2 and the luminance of the third sub-pixel SP3. Referring to Figure 5DAs described above, in the second sub-pixel SP2 of the display device 10 according to the comparative example, both the blue light and the green light are absorbed in the red color filter CFR, so that the luminance of the second sub-pixel SP2 is determined only by the red light emitted from the red light-emitting layer 32R of the second stack ST2. In the third sub-pixel SP3, the luminance of the third sub-pixel SP3 can be determined by the green light emitted from the green light-emitting layer 32G of the second stack ST2. However, in the second sub-pixel SP2 of the display device 100 according to the exemplary embodiment, the blue light and the green light from the light-emitting unit 132 are not absorbed in the red color filter CFR by being converted into red light by the second light conversion layer CCL2, thereby minimizing the amount of light loss. Further, in the second stack ST2 of the light-emitting unit 132 of the display device 100 according to the exemplary embodiment, since only the green light-emitting layer 132G is provided, the green light emitted from the light-emitting unit 132 can be increased compared to the comparative example, so that the luminance of the third sub-pixel SP3 can be improved. In the display device 100 according to the exemplary embodiment, the luminance of the second sub-pixel SP2 can be controlled by the second light conversion layer CCL2 and the red color filter CFR and the luminance of the third sub-pixel SP3 can be controlled by the green light-emitting layer 132G of the light-emitting unit 132. Therefore, unlike the display device 10 according to the comparative example including the red light-emitting layer 32R and the green light-emitting layer 32G having a trade-off relationship provided in one second stack ST2, in the display device 100 according to the exemplary embodiment, the red light and the green light are separately controlled so that they do not have a trade-off relationship, thereby easily improving the luminance of the second sub-pixel SP2 and the third sub-pixel SP3.

[0113] Next, referring to Figure 6 The wavelength of the light emitted from the fourth sub-pixel SP4 of the display device 10 according to the comparative example can have a peak at about 470 nm. Further, the wavelength of the light emitted from the fourth sub-pixel SP4 of the display device 100 according to the exemplary embodiment can also have a peak at about 470 nm. Therefore, each wavelength of the light emitted from the fourth sub-pixel SP4 of the display devices 10 and 100 according to the comparative example and the exemplary embodiment can also have a peak at about 470 nm, thereby becoming blue light.

[0114] Referring to Table 1 together, the luminance of light emitted from the fourth sub-pixel SP4 of the display device 10 according to the comparative example is 272 nit, and the luminance of light emitted from the fourth sub-pixel SP4 of the display device 100 according to the exemplary embodiment can be a similar level of 288 nit. The luminance of the fourth sub-pixel SP4 of the display device 10 and the display device 100 according to the comparative example and the exemplary embodiment is determined by the first blue light emitting layer 32B1, 132B1 and the second blue light emitting layer 32B2, 132B2 of the first stack ST1 and the third stack ST3 of the light emitting unit 32, 132, respectively. Thus, the luminance of the fourth sub-pixel SP4 in the display device 100 according to the exemplary embodiment can be similar to the luminance of the fourth sub-pixel SP4 in the display device 10 according to the comparative example.

[0115] In the display device 100 according to the exemplary embodiment of the present application, the second light conversion layer CCL2 and the red color filter CFR are provided in the second sub-pixel SP2 and the light emitting unit 132 includes the green light emitting layer 132G, thereby improving the luminance of the display device 100. In the case of the display device 10 according to the comparative example, the red light emitting layer 32R and the green light emitting layer 32G are provided in one second stack ST2, thereby having a trade-off relationship. Accordingly, when the efficiency of the red light emitting layer 32R is improved, the efficiency of the green light emitting layer 32G is decreased; and when the efficiency of the green light emitting layer 32G is improved, the efficiency of the red light emitting layer 32R is decreased, such that there is a limitation in improving the luminance. Unlike this, in the display device 100 according to the exemplary embodiment of the present application, the second light conversion layer CCL2 that converts the blue light and the green light emitted from the light emitting unit 132 into the red light is provided in the second sub-pixel SP2, thereby minimizing the light absorbed and lost in the red color filter CFR. At this time, the thickness of the second light conversion layer CCL2 is configured to be at least greater than the thickness of the first light conversion layer CCL1, thereby improving the ratio of converting the blue light and the green light emitted from the light emitting unit 132 into the red light and improving the luminance of the red light finally displayed in the second sub-pixel SP2. Further, in the second stack ST2 of the light emitting unit 132 of the display device 100 according to the exemplary embodiment of the present application, the green light emitting layer 132G that emits only the green light is provided, compared to the comparative example in which the red light emitting layer 32R and the green light emitting layer 32G are provided in one second stack ST2. Accordingly, the green light emitted from the light emitting unit 132 can be increased and the luminance of the third sub-pixel SP3 can be improved. Accordingly, in the display device 100 according to the exemplary embodiment of the present application, the second light conversion layer CCL2 and the red color filter CFR are provided in the second sub-pixel SP2 to control the luminance of the second sub-pixel SP2 that displays the red light. Further, only one green light emitting layer 132G is provided in the second stack ST2 of the light emitting unit 132 to control the luminance of the third sub-pixel SP3 that displays the green light, thereby improving the overall luminance of the display device 100.

[0116] Figures 1 to 3 is a view schematically illustrating a structure of a display device according to another exemplary embodiment of the present application. As compared with the display device 100 of Figure 6 the display device 100 of Figure 6 The display device 600 is substantially the same as the display device 100 in other configurations, and thus a repeated description will be omitted.

[0117] Referring to Figure 7The first light conversion layer CCL1 includes a plurality of first light conversion layer patterns CCL1a. The plurality of first light conversion layer patterns CCL1a can be disposed to be spaced apart from each other. The first light conversion layer CCL1 is composed of the plurality of first light conversion layer patterns CCL1a spaced apart from each other, so that it is easy to control the light conversion efficiency of the first light conversion layer CCL1.

[0118] As the interval between the first light conversion layer patterns CCL1a decreases, that is, as the blank space between the first light conversion layer patterns CCL1a decreases, the probability that the blue light and the green light from the light emitting unit 132 is incident to the first light conversion layer CCL1 can increase. Thus, in the first light conversion layer CCL1, the ratio that the blue light and the green light are converted into the red light can increase.

[0119] On the contrary, as the interval between the first light conversion layer patterns CCL1a increases, that is, as the blank space between the first light conversion layer patterns CCL1a increases, the probability that the blue light and the green light from the light emitting unit 132 is incident to the first light conversion layer CCL1 can decrease. Thus, in the first light conversion layer CCL1, the ratio that the blue light and the green light are converted into the red light can decrease.

[0120] In this case, according to the light conversion efficiency design of the first light conversion layer CCL1, the thickness of each first light conversion layer pattern CCL1a can be different from or equal to the thickness of the second light conversion layer CCL2. For example, the interval between the first light conversion layer patterns CCL1a becomes wide, or the thickness of each first light conversion layer pattern CCL1a is smaller than the thickness of the second light conversion layer CCL2, thereby lowering the light conversion efficiency of the first light conversion layer CCL1. For example, the interval between the first light conversion layer patterns CCL1a becomes narrow, or the thickness of each first light conversion layer pattern CCL1a is greater than the thickness of the second light conversion layer CCL2, thereby increasing the light conversion efficiency of the first light conversion layer CCL1.

[0121] Further, according to the light conversion efficiency design of the first light conversion layer CCL1, the concentration of the light conversion material of each first light conversion layer pattern CCL1a can be different from or equal to the concentration of the light conversion material of the second light conversion layer CCL2. For example, the interval between the first light conversion layer patterns CCL1a becomes wide, or the concentration of the light conversion material of each first light conversion layer pattern CCL1a is smaller than the concentration of the light conversion material of the second light conversion layer CCL2, thereby lowering the light conversion efficiency of the first light conversion layer CCL1. For example, the interval between the first light conversion layer patterns CCL1a becomes narrow, or the concentration of the light conversion material of each first light conversion layer pattern CCL1a is greater than the concentration of the light conversion material of the second light conversion layer CCL2, thereby increasing the light conversion efficiency of the first light conversion layer CCL1.

[0122] Further, according to the light conversion efficiency design of the first light conversion layer CCL1, the light conversion material of each of the first light conversion layer patterns CCL1a can be different from or the same as the light conversion material of the second light conversion layer CCL2. For example, the interval between the first light conversion layer patterns CCL1a is widened, or the light conversion material of the first light conversion layer patterns CCL1a is configured to be a light conversion material having a lower efficiency than the light conversion material of the second light conversion layer CCL2, thereby reducing the light conversion efficiency of the first light conversion layer CCL1. For example, the interval between the first light conversion layer patterns CCL1a is narrowed, or the light conversion material of the first light conversion layer patterns CCL1a is configured to be a light conversion material having a higher efficiency than the light conversion material of the second light conversion layer CCL2, thereby increasing the light conversion efficiency of the first light conversion layer CCL1.

[0123] Therefore, the thickness of the first light conversion layer CCL1 and the second light conversion layer CCL2, the concentration of the light conversion material of each of the first light conversion layer CCL1 and the second light conversion layer CCL2, and the type of the light conversion material can be variously configured considering the interval between the first light conversion layer patterns CCL1a, but are not limited thereto. As an example, the thickness of the first light conversion layer CCL1 can be less than the thickness of the second light conversion layer CCL2, and at this time, the concentration of the light conversion material in the first light conversion layer CCL1 can be equal to the concentration of the light conversion material in the second light conversion layer CCL2. Alternatively, the thickness of the first light conversion layer CCL1 can be equal to the thickness of the second light conversion layer CCL2, and at this time, the concentration of the light conversion material in the first light conversion layer CCL1 can be lower than the concentration of the light conversion material in the second light conversion layer CCL2.

[0124] In the display device 600 according to another exemplary embodiment of the present application, the first light conversion layer CCL1 is composed of a plurality of first light conversion layer patterns CCL1a spaced apart from each other, thereby easily controlling the light conversion efficiency of the first light conversion layer CCL1. For example, when the interval between the first light conversion layer patterns CCL1a is widened, the probability that the blue light and the green light of the light emitting unit 132 is incident to the first light conversion layer CCL1 can decrease, and the ratio to be converted into the red light in the first light conversion layer CCL1 can decrease. For example, when the interval between the first light conversion layer patterns CCL1a is narrowed, the probability that the blue light and the green light of the light emitting unit 132 is incident to the first light conversion layer CCL1 can increase, and the ratio to be converted into the red light in the first light conversion layer CCL1 can increase. Therefore, in the display device 600 according to another exemplary embodiment of the present application, the first light conversion layer CCL1 is composed of a plurality of first light conversion layer patterns CCL1a, thereby easily controlling the light conversion efficiency of the first light conversion layer CCL1 and the color temperature of the white light.

[0125] Figures 1 to 3is a diagram schematically illustrating a structure of a display device according to a further exemplary embodiment of the present application. As with Figure 7 The display device 100 according to the present application differs from the display device 100 of FIG. 1 in that the first light conversion layer CCL1 and the second light conversion layer CCL2 are different, ​ The display device 700 according to the present application is substantially the same as the display device 100 in other configurations, and thus repetitive descriptions will be omitted.

[0126] The first light conversion layer CCL1 includes a base member and a first light conversion material. The first light conversion layer CCL1 can be formed of a base member in which the first light conversion material is distributed. Also, the second light conversion layer CCL2 includes a base member and a second light conversion material. The second light conversion layer CCL2 can be formed of a base member in which the second light conversion material is distributed. In this case, the first light conversion material and the second light conversion material can be different materials.

[0127] The first light conversion material can be a material having a higher efficiency in converting green light into red light than in converting blue light into red light. Specifically, the first light conversion layer CCL1 is disposed in the first sub-pixel SP1 that is a white sub-pixel SP, thereby converting some of the blue light and green light from the light emitting unit 132 into red light, thereby realizing white light. At this time, the color temperature of the white light can be controlled by adjusting the ratio of the blue light, green light, and red light that form the white light. For example, when the color temperature of the white light increases to realize blue-based white light, the blue light can occupy the largest ratio and the red light can occupy the smallest ratio. At this time, in order to realize white light having a high color temperature, the ratio of the green light converted into red light needs to be higher than the ratio of the blue light converted into red light among the blue light and green light emitted from the light emitting unit 132, thereby increasing the ratio of the blue light in the white light. If the blue light is more converted into red light than the green light in the first light conversion layer CCL1, the ratio of the blue light in the white light can eventually decrease, making it difficult to realize white light having a high color temperature. As a result, the first light conversion material can be made of a material having a higher efficiency in converting green light into red light than in converting blue light into red light.

[0128] The second light conversion material can be a material having a higher efficiency in converting blue light into red light than the first light conversion material. Also, the second light conversion material can be a material having excellent efficiency in both converting blue light into red light and converting green light into red light. The second light conversion layer CCL2 is provided in the second sub-pixel SP2 which is a red sub-pixel SP, thereby converting some of the blue light and green light from the light emitting unit 132 into red light, thereby realizing red light. At this time, the remaining light of the blue light and green light which is not converted into red light in the second light conversion layer CCL2 is absorbed in the red color filter CFR without being transmitted to the outside of the display device 700. That is, the blue light and green light which is not converted into red light in the second light conversion layer CCL2 can be lost due to the red color filter CFR, resulting in a decrease in the brightness of the second sub-pixel SP2. Thus, the second light conversion material of the second light conversion layer CCL2 can be made of a material having excellent efficiency in converting blue light and green light into red light, and can be made of a material having at least higher efficiency in converting blue light into red light than the first light conversion material. As the efficiency of the second light conversion material in converting blue light and green light into red light increases, the light which is absorbed and lost in the red color filter CFR can be reduced, and the brightness of the red light finally displayed in the second sub-pixel SP2 can be improved.

[0129] The materials or sizes of the first light conversion material and the second light conversion material can be variously configured. When the first light conversion material and the second light conversion material are made of different materials, each of the first light conversion material and the second light conversion material can be made of any one of quantum dot materials such as InAs, InP, or PbS, but is not limited thereto.

[0130] When the first light conversion material and the second light conversion material are made of the same material, the sizes of the first light conversion material and the second light conversion material can be different from each other. In the case of quantum dots, as the size, i.e., diameter, increases, light close to red light can be emitted, and as the diameter decreases, light close to blue light can be emitted. For example, if the diameter of a quantum dot is 2 nm, that is, the size of about 15 atoms, the quantum dot can be a blue quantum dot; if the diameter of a quantum dot is 3 nm, that is, the size of about 30 atoms, the quantum dot can be a green quantum dot; and if the diameter of a quantum dot is 7 nm, that is, the size of about 150 atoms, the quantum dot can be a red quantum dot. Thus, in the case of the second light conversion layer having a relatively high efficiency in converting blue light and green light into red light, the second light conversion layer can have a larger size than the first light conversion layer. Thus, the sizes of the first light conversion material and the second light conversion material can be different from each other, such that the red light conversion efficiency of each of the first light conversion material and the second light conversion material can be designed to be different.

[0131] Further, in the case of the second light conversion layer CCL2, in order to increase the ratio of conversion of blue light and green light into red light, the concentration of the second light conversion material is configured to be high or the thickness of the second light conversion layer CCL2 is configured to be thick, thereby further increasing the light conversion efficiency.

[0132] In the display device 700 according to the still another exemplary embodiment of the present application, the first light conversion material of the first light conversion layer CCL1 and the second light conversion material of the second light conversion layer CCL2 can be configured differently based on the characteristics of each sub-pixel SP. In the case of the first sub-pixel SP1, in order to realize white light having a high color temperature, the ratio of conversion of green light among blue light and green light from the light emitting unit 132 into red light can be configured to be higher than the ratio of conversion of blue light into red light. White light having a high color temperature is blue-based white light, and as the ratio of blue light among blue light, green light, and red light that are mixed to form white light increases, the color temperature can increase. As a result, the first light conversion layer CCL1 is made of a first light conversion material having a higher ratio of conversion of green light into red light than a ratio of conversion of blue light into red light, thereby realizing white light having a higher color temperature. In the case of the second sub-pixel SP2, blue light and green light from the light emitting unit 132 are converted into red light to the greatest extent in the second light conversion layer CCL2, to reduce light loss in the red color filter CFR, thereby realizing red light having a high luminance. That is, the second light conversion material of the second light conversion layer CCL2 is made of a material having a high efficiency of conversion of both green light and blue light into red light, to convert light emitted from the light emitting unit 132 into red light to the greatest extent. Therefore, light that is absorbed and lost in the red color filter CFR can be minimized and the luminance of red light finally displayed in the second sub-pixel SP2 can be improved. Thus, in the display device 700 according to the still another exemplary embodiment of the present application, the first light conversion material of the first light conversion layer CCL1 and the second light conversion material of the second light conversion layer CCL2 are configured differently to realize white light having a high color temperature while realizing red light having a high luminance, thereby improving the display quality of the display device 700.

[0133] The exemplary embodiments of the present application can also be described as follows:

[0134] According to an aspect of the present application, a display device includes: a light emitting element disposed in each of a plurality of sub-pixels, the light emitting element including a first blue light emitting layer, a green light emitting layer on the first blue light emitting layer, and a second blue light emitting layer on the green light emitting layer; a first light conversion layer disposed in a first sub-pixel among the plurality of sub-pixels; and a second light conversion layer disposed in a second sub-pixel among the plurality of sub-pixels and having a higher light conversion efficiency than the first light conversion layer.

[0135] The first light conversion layer and the second light conversion layer can convert light emitted from the first blue light emitting layer, the green light emitting layer, and the second blue light emitting layer into red light.

[0136] The first light conversion layer can have a thickness less than a thickness of the second light conversion layer.

[0137] The first light conversion layer and the second light conversion layer can each include a base member and a light conversion material distributed in the base member. The concentration of the light conversion material in the first light conversion layer can be lower than the concentration of the light conversion material in the second light conversion layer.

[0138] The first light conversion layer can include a plurality of first light conversion layer patterns spaced apart from each other.

[0139] The first light conversion layer can have a higher efficiency of converting green light into red light than an efficiency of converting blue light into red light.

[0140] The second light conversion layer can have a higher efficiency of converting blue light into red light than an efficiency of converting blue light into red light by the first light conversion layer.

[0141] The display device can further include a red color filter disposed to overlap the second light conversion layer. The second light conversion layer can be disposed closer to the light emitting element than the red color filter.

[0142] In a cross-section, the second light conversion layer can have a width less than or equal to a width of the red color filter.

[0143] The first sub-pixel can be a white sub-pixel, and the second sub-pixel can be a red sub-pixel.

[0144] According to another aspect of the present application, a display device includes a light emitting unit disposed in a plurality of sub-pixels including a plurality of white sub-pixels and a plurality of red sub-pixels, the light emitting unit including a blue light emitting layer and a green light emitting layer, a first light conversion layer disposed in the plurality of white sub-pixels to convert light emitted from the light emitting unit into red light, and a second light conversion layer disposed in the plurality of red sub-pixels to convert light emitted from the light emitting unit into red light, wherein the second light conversion layer has a higher light conversion efficiency than the first light conversion layer.

[0145] The first light conversion layer and the second light conversion layer can include a light conversion material coated on a base member.

[0146] The first light conversion layer can have a thickness less than a thickness of the second light conversion layer, and a concentration of the light conversion material in the first light conversion layer can be equal to a concentration of the light conversion material in the second light conversion layer.

[0147] The first light conversion layer can have a thickness equal to a thickness of the second light conversion layer, and a concentration of the light conversion material in the first light conversion layer can be less than a concentration of the light conversion material in the second light conversion layer.

[0148] The light conversion material can include a first light conversion material disposed in the first light conversion layer, and a second light conversion material disposed in the second light conversion layer and having a different material or size from the first light conversion material. The first light conversion material can have a higher efficiency in converting green light into red light than in converting blue light into red light.

[0149] The second light conversion material can have a higher efficiency in converting blue light into red light than the first light conversion material in converting blue light into red light.

[0150] The first light conversion layer can include a plurality of first light conversion layer patterns disposed on one white sub-pixel of the plurality of white sub-pixels, and the plurality of first light conversion layer patterns can be spaced apart from each other.

[0151] The display apparatus can further include a red color filter disposed under the second light conversion layer in each of the plurality of red sub-pixels. In a plan view, a size of the red color filter can be greater than or equal to a size of the second light conversion layer.

[0152] Although exemplary embodiments of the present application have been described in detail with reference to the accompanying drawings, the present application is not limited thereto and can be embodied in various forms. Therefore, the exemplary embodiments of the present application are provided only for illustrative purposes, and are not intended to limit the technical idea of the present application. The scope of the technical idea of the present application is not limited to this. Therefore, it should be understood that the above-described exemplary embodiments are illustrative only and are not limiting of the present application in all aspects. The scope of protection of the present application should be interpreted based on the appended claims, and all technical ideas within the equivalent scope thereof should be interpreted to fall within the scope of the present application.

Claims

1. A display device comprising: a light emitting element provided in each of a plurality of sub-pixels, the light emitting element including a first blue light emitting layer, a green light emitting layer on the first blue light emitting layer, and a second blue light emitting layer on the green light emitting layer; a first light conversion layer provided in a first sub-pixel among the plurality of sub-pixels; and a second light conversion layer provided in a second sub-pixel among the plurality of sub-pixels and having a higher light conversion efficiency than the first light conversion layer, such that a ratio of conversion of blue light and green light to red light in the first light conversion layer is lower than a ratio of conversion of blue light and green light to red light in the second light conversion layer, so that the first sub-pixel displays a blue-based white light, wherein a thickness of the first light conversion layer is smaller than a thickness of the second light conversion layer, and wherein the first sub-pixel is a white sub-pixel and the second sub-pixel is a red sub-pixel.

2. A display device comprising: a light emitting element provided in each of a plurality of sub-pixels, the light emitting element including a first blue light emitting layer, a green light emitting layer on the first blue light emitting layer, and a second blue light emitting layer on the green light emitting layer; a first light conversion layer provided in a first sub-pixel among the plurality of sub-pixels; and a second light conversion layer provided in a second sub-pixel among the plurality of sub-pixels and having a higher light conversion efficiency than the first light conversion layer, such that a ratio of conversion of blue light and green light to red light in the first light conversion layer is lower than a ratio of conversion of blue light and green light to red light in the second light conversion layer, so that the first sub-pixel displays a blue-based white light, wherein each of the first light conversion layer and the second light conversion layer includes: a base member; and a light conversion material distributed in the base member, wherein a concentration of the light conversion material in the first light conversion layer is lower than a concentration of the light conversion material in the second light conversion layer, and wherein the first sub-pixel is a white sub-pixel and the second sub-pixel is a red sub-pixel.

3. A display device comprising: a light emitting element provided in each of a plurality of sub-pixels, the light emitting element including a first blue light emitting layer, a green light emitting layer on the first blue light emitting layer, and a second blue light emitting layer on the green light emitting layer; a first light conversion layer provided in a first sub-pixel among the plurality of sub-pixels; and a second light conversion layer provided in a second sub-pixel among the plurality of sub-pixels and having a higher light conversion efficiency than the first light conversion layer, such that a ratio of conversion of blue light and green light to red light in the first light conversion layer is lower than a ratio of conversion of blue light and green light to red light in the second light conversion layer, so that the first sub-pixel displays a blue-based white light, wherein the first light conversion layer includes a plurality of first light conversion layer patterns separated from each other, and wherein the first sub-pixel is a white sub-pixel and the second sub-pixel is a red sub-pixel. ​ ​ ​ ​ 4. The display device according to any one of claims 1 to 3, wherein the first light conversion layer and the second light conversion layer convert light emitted from the first blue light emitting layer, the green light emitting layer, and the second blue light emitting layer into red light.

5. The display device according to claim 4, wherein the first light conversion layer has a higher efficiency of converting green light into red light than an efficiency of converting blue light into red light.

6. The display device according to claim 4, wherein the second light conversion layer has a higher efficiency of converting blue light into red light than an efficiency of converting blue light into red light by the first light conversion layer.

7. The display device according to any one of claims 1 to 3, further comprising: a red color filter disposed to overlap with the second light conversion layer, wherein the second light conversion layer is disposed closer to the light emitting element than the red color filter.

8. The display device according to claim 7, wherein the second light conversion layer has a width smaller than or equal to a width of the red color filter in a cross section.

9. A display device comprising: a light emitting unit disposed in a plurality of sub-pixels including a plurality of white sub-pixels and a plurality of red sub-pixels, the light emitting unit including a blue light emitting layer that emits blue light and a green light emitting layer that emits green light; a first light conversion layer disposed in the plurality of white sub-pixels to convert light emitted from the light emitting unit into red light; and a second light conversion layer disposed in the plurality of red sub-pixels to convert light emitted from the light emitting unit into red light, wherein the second light conversion layer has a higher light conversion efficiency than the first light conversion layer, such that a ratio of converting blue light and green light into red light in the first light conversion layer is lower than a ratio of converting blue light and green light into red light in the second light conversion layer, so that the white sub-pixel displays blue-based white light, wherein each of the first light conversion layer and the second light conversion layer includes a light conversion material coated on a base member, and wherein the first light conversion layer has a thickness smaller than a thickness of the second light conversion layer, and a concentration of the light conversion material in the first light conversion layer is equal to a concentration of the light conversion material in the second light conversion layer.

10. A display device comprising: a light emitting unit disposed in a plurality of sub-pixels including a plurality of white sub-pixels and a plurality of red sub-pixels, the light emitting unit including a blue light emitting layer that emits blue light and a green light emitting layer that emits green light; a first light conversion layer disposed in the plurality of white sub-pixels to convert light emitted from the light emitting unit into red light; and a second light conversion layer disposed in the plurality of red sub-pixels to convert light emitted from the light emitting unit into red light, wherein the second light conversion layer has a higher light conversion efficiency than the first light conversion layer, such that a ratio of converting blue light and green light into red light in the first light conversion layer is lower than a ratio of converting blue light and green light into red light in the second light conversion layer, so that the white sub-pixel displays blue-based white light, wherein each of the first light conversion layer and the second light conversion layer includes a light conversion material coated on a base member, and wherein the first light conversion layer has a thickness smaller than a thickness of the second light conversion layer, and a concentration of the light conversion material in the first light conversion layer is equal to a concentration of the light conversion material in the second light conversion layer. wherein the light conversion efficiency of the second light conversion layer is higher than the light conversion efficiency of the first light conversion layer, such that the ratio of converting blue light and green light into red light in the first light conversion layer is lower than the ratio of converting blue light and green light into red light in the second light conversion layer, so that the white sub-pixel displays a blue-based white light, and wherein each of the first light conversion layer and the second light conversion layer comprises a light conversion material coated on a base member, and wherein the thickness of the first light conversion layer is equal to the thickness of the second light conversion layer, and the concentration of the light conversion material in the first light conversion layer is lower than the concentration of the light conversion material in the second light conversion layer.

11. A display device comprising: a light emitting unit disposed in a plurality of sub-pixels including a plurality of white sub-pixels and a plurality of red sub-pixels, the light emitting unit including a light emitting layer emitting blue light and a light emitting layer emitting green; a first light conversion layer disposed in the plurality of white sub-pixels to convert light emitted from the light emitting unit into red light; and a second light conversion layer disposed in the plurality of red sub-pixels to convert light emitted from the light emitting unit into red light, wherein the light conversion efficiency of the second light conversion layer is higher than the light conversion efficiency of the first light conversion layer, such that the ratio of converting blue light and green light into red light in the first light conversion layer is lower than the ratio of converting blue light and green light into red light in the second light conversion layer, so that the white sub-pixel displays a blue-based white light, and wherein the first light conversion layer includes a plurality of first light conversion layer patterns disposed on one white sub-pixel of the plurality of white sub-pixels, and the plurality of first light conversion layer patterns are spaced apart from each other.

12. A display device comprising: a light emitting unit disposed in a plurality of sub-pixels including a plurality of white sub-pixels and a plurality of red sub-pixels, the light emitting unit including a light emitting layer emitting blue light and a light emitting layer emitting green; a first light conversion layer disposed in the plurality of white sub-pixels to convert light emitted from the light emitting unit into red light; and a second light conversion layer disposed in the plurality of red sub-pixels to convert light emitted from the light emitting unit into red light, wherein the light conversion efficiency of the second light conversion layer is higher than the light conversion efficiency of the first light conversion layer, such that the ratio of converting blue light and green light into red light in the first light conversion layer is lower than the ratio of converting blue light and green light into red light in the second light conversion layer, so that the white sub-pixel displays a blue-based white light, and wherein each of the first light conversion layer and the second light conversion layer comprises a light conversion material coated on a base member, wherein the light conversion material includes: a first light conversion material disposed in the first light conversion layer; and a second light conversion material disposed in the second light conversion layer and having a different material or size from the first light conversion material, wherein the first light conversion material has a higher efficiency of converting green light to red light than converting blue light to red light.

13. The display device according to claim 12, wherein the second light conversion material has a higher efficiency of converting blue light to red light than the first light conversion material has of converting blue light to red light.

14. The display device according to any one of claims 9 to 12, further comprising: a red color filter disposed below the second light conversion layer in each of the plurality of red sub-pixels, wherein the red color filter has a size greater than or equal to a size of the second light conversion layer in a plane.

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