White light emitting device and display device using the same

Abstract

A white light emitting device and a display device using the white light emitting device are disclosed, which can prevent brightness change caused by viewing angle change, improve color deviation, and reduce driving voltage at the same time by means of the internal laminate structure and the change in the thickness of the light emitting side electrode with respect to the vertical distance from the lower surface of the first electrode to the lower surface of the second electrode.

Description

Technical Field

[0001] The present disclosure relates to a light emitting device, and more particularly, to a white light emitting device and a display device using the white light emitting device, which can improve efficiency, prevent brightness change and color change according to viewing angle, and reduce driving voltage by changing the structure. Background Art

[0002] Recently, in order to omit a separate light source and achieve compactness of the device and clear color display, self-emissive display devices are considered competitive applications. Self-emissive display devices can be classified into organic light emitting display devices and inorganic light emitting display devices according to internal light emitting materials.

[0003] In a self-emissive display device, a plurality of sub-pixels are provided, and a light emitting device is provided in each sub-pixel without a separate light source.

[0004] The display device is required to have high resolution and high integration. Since the organic layer and / or the light emitting layer in a tandem device are commonly formed on a substrate without a fine metal mask (FMM), a tandem type white light emitting device (hereinafter referred to as "white light emitting device") has been proposed and studied. Summary of the Invention

[0005] A tandem type display device includes a plurality of light emitting layers overlapping each other. Each light emitting layer has different resonance characteristics, so color defects may be observed when a user views the tandem type display device at a certain viewing angle.

[0006] Accordingly, the present disclosure relates to a white light emitting device and a display device using the white light emitting device, which substantially eliminate one or more problems caused by limitations and disadvantages of the related art.

[0007] An object of the present disclosure is to provide a white light emitting device and a display device using the white light emitting device, which can prevent brightness change caused by viewing angle change, prevent or reduce color deviation, and reduce driving voltage by changing the internal laminate structure and the relationship with the light emitting side electrode.

[0008] A white light emitting device according to an embodiment of the present disclosure may include a first laminate on a first electrode, the first laminate including a red light emitting layer and a green light emitting layer; a charge generation layer on the first laminate; a second laminate on the charge generation layer, the second laminate including a blue light emitting layer; and a second electrode on the second laminate, wherein light is emitted through the first electrode, and wherein the thickness of the first electrode is 0.1 times or more and 0.26 times or less of the distance from the lower surface of the first electrode to the lower surface of the second electrode.

[0009] In addition, a display device according to an embodiment of the present disclosure may include: a substrate including a plurality of sub-pixels; thin film transistors at each sub-pixel; a first electrode connected to the thin film transistors at each sub-pixel; a white organic stack on the first electrode, the white organic stack including a first stack including a red light-emitting layer and a green light-emitting layer, a second stack including a blue light-emitting layer, and a charge generation layer between the first stack and the second stack; and a second electrode on the white organic stack. Light can be emitted from the white organic stack through the first electrode. The thickness of the first electrode may be 0.1 times or more and 0.26 times or less of the total thickness of the first electrode and the white organic stack.

[0010] It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the claimed present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings are included to provide a further understanding of the present disclosure and are incorporated into and constitute a part of this application. The drawings illustrate embodiments of the present disclosure and, together with the description, are used to explain the principles of the present disclosure. In the drawings:

[0012] Figure 1 is a schematic cross-sectional view of a white light-emitting device according to the present disclosure.

[0013] Figure 2 is according to Figure 1 a cross-sectional view of an embodiment of.

[0014] Figure 3 is a contour map showing the correspondence between each light-emitting color and the light-emitting layer in the white light-emitting device of the present disclosure.

[0015] Figure 4 is an illustration of including Figure 2 a cross-sectional view of a display device of a white light-emitting device.

[0016] Figure 5 is a cross-sectional view illustrating a first experimental example and a second experimental example.

[0017] Figure 6 is a graph illustrating color deviation according to viewing angle in the first experimental example and the second experimental example.

[0018] Figures 7A to 7C is a contour map illustrating the first experimental example to the third experimental example.

[0019] Figure 8 is a graph illustrating the light intensity according to wavelength of the white light-emitting device of the present disclosure.

[0020] Figure 9It is a graph showing the light intensity according to wavelength for each viewing angle of the white light emitting device of the present disclosure.

[0021] Figure 10 It is a graph showing the color deviation according to the viewing angle of the present disclosure.

[0022] Figure 11 It is a graph showing the J-V curve in the white light emitting device of the present disclosure.

[0023] Figure 12 It is a graph showing the 95% lifetime of the second experimental example and the fourth experimental example of the white light emitting device.

[0024] Figure 13 It is a graph showing the deviation of the driving voltage according to time in the first experimental example and the second experimental example.

[0025] Figure 14 It is a graph showing the deviation of the color temperature according to time in the white light emitting device of the present disclosure. Detailed Description

[0026] Now, preferred embodiments of the present disclosure will be described in detail, which are illustrated in the accompanying drawings. However, the present disclosure can be implemented in many alternative forms and should not be construed as limited to the embodiments set forth herein. The embodiments of the present disclosure are provided only to fully disclose the present disclosure and fully inform those skilled in the art of the scope of the present disclosure. Therefore, it should be understood that the intention is not to limit the present disclosure to the specific forms disclosed, but rather, the present disclosure covers all modifications, equivalents, and alternatives within the spirit and scope of the present disclosure as defined by the claims.

[0027] The shapes, sizes, ratios, angles, quantities, etc. disclosed in the accompanying drawings for describing the embodiments of the present disclosure are merely exemplary and do not limit the present disclosure. In the following description of the embodiments and the accompanying drawings, even if the same or similar elements are depicted in different drawings, they are denoted by the same reference numerals. In the following description of the embodiments of the present disclosure, when a detailed description of known functions and configurations incorporated herein may obscure the subject matter of the present disclosure, the detailed description of the known functions and configurations will be omitted. In the following description of the embodiments, the terms "comprising" and "having" will be construed as indicating the presence of one or more other features, quantities, steps, operations, elements, components, or combinations thereof described in the specification, rather than precluding the presence or adding the possibility of other features, quantities, steps, operations, elements, components, or combinations thereof. It will be understood that, unless otherwise specified, singular expressions include plural expressions.

[0028] When interpreting the elements included in the various embodiments of the present disclosure, unless otherwise specified, they will be construed as including an error range.

[0029] In the following description of the embodiments, it will be understood that when expressing a positional relationship, for example, when an element is "on", "above", "below", "next to", etc. another element, unless the terms "immediately" or "directly" are used, the two elements may be in direct contact with each other, or one or more other elements may be interposed between the two elements.

[0030] In the following description of the embodiments, it will be understood that when expressing a temporal relationship, for example, terms expressing the order of events such as "after", "subsequently", "next", "before" may cover a continuous relationship between events, or a discontinuous relationship between events, unless the terms "immediately" or "directly" are used.

[0031] In the following description of the embodiments, it will be understood that when using terms such as "first", "second", etc. to describe various elements, these terms are only used to distinguish the same or similar elements. Thus, without departing from the technical scope of the present disclosure, the first element described below may be referred to as the second element.

[0032] The features of the various embodiments of the present disclosure may be partially or wholly connected or combined with each other, and are technically driven differently and interlocked with each other, and the various embodiments may be implemented independently or together in combination with each other.

[0033] In the following description of the embodiments, an electroluminescence (EL) spectrum is calculated by multiplying the following two: (1) a photoluminescence (PL) spectrum, which reflects the unique characteristics of luminescent materials such as dopant materials or host materials contained in the organic light-emitting layer; and (2) an external coupling emission spectral curve, which is determined according to the structure and optical characteristics of an organic light-emitting device including the thickness of an organic layer (e.g., an electron transport layer, etc.).

[0034] Figure 1 is a cross-sectional view schematically illustrating a white light-emitting device according to the present disclosure, Figure 2 is according to Figure 1 a cross-sectional view of one embodiment of. Additionally, Figure 3 is a contour map showing each emission color and the corresponding position of the emission layer in the white light-emitting device of the present disclosure.

[0035] As Figure 1 and Figure 2As shown, the white light emitting device 2000 according to the present disclosure includes a first stack S1 on a first electrode 110, a charge generation layer 160 on the first stack S1, a second stack S2 on the charge generation layer 160, and a second electrode 120 on the second stack S2. The first stack S1 includes a red light emitting layer 141 and a green light emitting layer 142, and the second stack S2 includes a blue light emitting layer 150. It should be noted that although as Figure 2 shown, the green light emitting layer 142 is disposed on the red light emitting layer 141, embodiments of the present disclosure are not limited thereto. For example, the red light emitting layer 141 may also be disposed on the green light emitting layer 142.

[0036] In the white light emitting device 2000 of the present disclosure, each of the light emitting layers 141, 142, and 150 is located at a specific position. In addition, in the white light emitting device 2000, the thickness of the first electrode 110 is applied under specific conditions with respect to the distance d from the lower surface of the first electrode 110 to the second electrode 120. Thus, in the contour map of the white organic stack WEL that defines each light emitting position, the red light emitting layer 141, the green light emitting layer 142, and the blue light emitting layer 150 are applied to respective contour line regions having a gentle single slope with respect to the distance d from the lower surface of the first electrode 110 to the second electrode 120. Therefore, each position of the red light emitting layer 141, the green light emitting layer 142, and the blue light emitting layer 150 is configured to prevent interference from other color emissions and maintain stable brightness and color characteristics with respect to viewing angle changes.

[0037] In the white light emitting device 2000 of the present disclosure, the first electrode 110 is the light emitting side, and light from inside the white light emitting device 2000 is emitted through the first electrode 110. The first electrode 110 is a transparent electrode and the second electrode 120 is a reflective electrode. Light generated from the red light emitting layer 141 and the green light emitting layer 142 of the first stack S1 and light generated from the blue light emitting layer 150 of the second stack S2 resonate between the first electrode 110 and the second electrode 120 and finally are emitted through the first electrode 110. The first electrode 110 may be a transparent oxide electrode containing at least two elements selected from indium In, tin Sn, zinc Zn, titanium Ti, and gallium Ga. For example, the first electrode 110 may be formed of a material such as ITO or IZO. The second electrode 120 may be formed of Al, an Al alloy, Ag, an Ag alloy, Mg, a Mg alloy, or APC (Ag - Pd - Cu) including a reflective electrode, etc.

[0038] Functionally, the first electrode 110 may be referred to as an anode and the second electrode 120 may be referred to as a cathode.

[0039] The white light emitting device 2000 of the present disclosure is configured to reduce color viewing angle characteristics that change according to the viewing angle. For example, in the white light emitting device 2000, the light emitting layers of the first laminate and the second laminate are located in contour regions each having a gentle profile, so that each light emitting layer is located at a position where interference from the emission of other colors does not occur, as Figure 3 shown. Therefore, color variability according to the viewing angle can be reduced or prevented. For example, the contour regions where the red or green light emitting layer is located and the contour regions where the blue light emitting layer is located are arranged to have different inclinations, and as the viewing angle increases, the difference between the angle corresponding to the optimal light emitting region of the red or green light emitting layer and the angle corresponding to the optimal light emitting region of the blue light emitting layer becomes larger. Therefore, it causes a visibility difference between the red or green brightness change and the blue brightness change. The white light emitting device 2000 of the present disclosure is used to reduce or prevent the visibility difference between the red or green brightness change and the blue brightness change, and each of the red light emitting layer, the green light emitting layer, and the blue light emitting layer is provided in a contour region having a single gentle slope.

[0040] In addition, in the white light emitting device 2000 of the present disclosure, the thickness Ad of the first electrode 110 may be 0.1 times or more and 0.26 times or less of the distance "d" from the lower surface of the first electrode 110 to the lower surface of the second electrode 120.

[0041] Herein, the distance "d" from the lower surface of the first electrode 110 to the lower surface of the second electrode 120 may be 150 nm to 200 nm. The distance "d" includes the thickness of the first electrode 110 and the thickness of the white organic laminate WEL containing the organic material. Specifically, in the distance d from the lower surface of the first electrode 110 to the lower surface of the second electrode 120, there are the first electrode 110 and the white organic laminate WEL including two laminates, but the distance d is 200 nm or less. Therefore, even though the white light emitting device 2000 has two laminates, the white light emitting device 2000 of the present disclosure is substantially thinner, so the distance between the red light emitting layer 141 located at the bottom among the light emitting layers of the white organic laminate WEL and the blue light emitting layer 150 located at the top among the light emitting layers of the white organic laminate WEL is very short. For example, the red light emitting layer 141 and the green light emitting layer 142 may be in contact with each other, and the respective thicknesses of the layers 132, 160, and 133 between the green light emitting layer 142 and the blue light emitting layer 150 may be thin. In addition, since the thickness Ad of the first electrode 110 is proportional to the distance d from the lower surface of the first electrode 110 to the lower surface of the second electrode 120, the thickness Ad of the first electrode 110 is smaller than the thickness of a white organic light emitting device having a known double laminate structure.

[0042] Between the first laminate S1 and the second laminate S2, there is a charge generation layer CGL(160) including an n-type charge generation layer n-CGL(161) and a p-type charge generation layer p-CGL(162). The n-type charge generation layer n-CGL(161) generates electrons and supplies the electrons to the first laminate S1 away from the second electrode 120. The p-type charge generation layer p-CGL(162) generates holes and supplies the holes to the second laminate S2 away from the first electrode 110. The charge generation layer 160 can be formed by two layers as shown in Figure 2 or can be formed by one layer including different dopants as shown in Figure 1 . In the white light emitting device 2000 of the present disclosure, the charge generation layer 160 is provided to supply holes and electrons to adjacent laminates and maintain charge balance in each light emitting layer of each of the laminates S1 and S2.

[0043] The first laminate S1 can include a first common layer 131 between the red light emitting layer 141 and the first electrode 110, and a second common layer 132 between the green light emitting layer 142 and the charge generation layer 160. The first common layer 131 can include a hole injection layer and a hole transport layer. In some cases, the first common layer 131 further includes an electron blocking layer adjacent to the red light emitting layer 141. The second common layer 132 can include an electron transport layer.

[0044] In addition, the second laminate 2 can include a third common layer 133 between the charge generation layer 160 and the blue light emitting layer 150 and a fourth common layer 134 between the blue light emitting layer 150 and the second electrode 120. The third common layer 133 can include a hole transport layer, and the fourth common layer 134 can include an electron transport layer and an electron injection layer.

[0045] In each laminate, the first common layer 131 and the third common layer 133 located below the light emitting layer are related to the transport of holes, and the second common layer 132 and the fourth common layer 134 located above the light emitting layer are related to the transport of electrons.

[0046] The positions (vertical distances) of the red light emitting layer 141, the green light emitting layer 142, and the blue light emitting layer 150 from the second electrode 120 can be adjusted by controlling the thicknesses of the common layers 131, 132, 133, and 134 of the laminate.

[0047] The host material used in the red light-emitting layer 141 may include an aryl group as the core and may include one of the following: an aryl group, a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, a substituted or unsubstituted fused aryl group having 10 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 2 to 24 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 24 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 24 carbon atoms, a substituted or unsubstituted aryloxy group having 6 to 24 carbon atoms, a substituted or unsubstituted alkylsilyl group having 1 to 24 carbon atoms, a substituted or unsubstituted arylsilyl group having 6 to 24 carbon atoms, a cyano group, a halogen group, deuterium, and hydrogen, and R-R14 may form a fused ring with an adjacent substituent group.

[0048] In addition, the aryl group as the core component may include one of the following: phenyl, naphthalene, fluorene, carbazole, phenazine, phenanthroline, phenanthridine, acridine, cinnoline, quinazoline, quinoxaline, naphthyridine, phthalazine, quinazine, indole, indazole, pyridazine, pyrazine, pyrimidine, pyridine, pyrazole, imidazole, and pyrrole.

[0049] In one example, the host material of the red light-emitting layer 141 may include one or more of CBP, CDBP, mCP, BCP, BAlq, and TAZ.

[0050] In addition, the red light-emitting layer 141 includes a dopant to emit red light, and the phosphorescent dopant may be, for example, Ir(piz)3 (tris)(1-phenylisoquinoline)iridium(III), Ir(piq)2(acac) (bis)(1-phenylisoquinoline)(acetylacetonate)iridium(III), Ir(bip)2(acac) (bis)2-benzothiophen-2-yl-pyridine(acetylacetonate)iridium(III), or Ir(BT)2(acac) (bis)(2-phenylbenzothiazole)(acetylacetonate)iridium(III), but is not limited thereto.

[0051] The host material of the green light-emitting layer 142 may include C-545T (10-(2-benzothiazolyl))-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H), 11H-[1]benzopyrano[6,7,8-ij]quinolin-11-one and its derivatives using Alq3 as a matrix, quinacridone derivatives, and carbazole derivatives, such as CBP, mCP, TCTA, and TCP. Although Alq3 can emit green light by itself when used as a host, a green dopant is included to improve the green light emission efficiency, and the green dopant may be one of a phosphorescent dopant and a fluorescent dopant. For example, the green dopant may be Ir(mppy)3, Ir(ppy)3, or Ir(ppy)2(acac).

[0052] Here, the blue light-emitting layer 150 may include at least one blue host and at least one blue dopant. Specifically, the blue light-emitting layer 150 may be formed by doping a pyrene derivative blue dopant or a boron derivative blue dopant in at least one host selected from anthracene derivatives, pyrene derivatives, and perylene derivatives.

[0053] The respective wavelengths of the red light-emitting layer 141, the green light-emitting layer 142, and the blue light-emitting layer 150 may be adjusted by changing the substituents of their dopants.

[0054] The white light-emitting device 2000 of the present disclosure realizes a 2-stack 3-peak structure capable of emitting colors, in which red, green, and blue can be distinguished in two stacks.

[0055] Several methods may be employed to represent white light emission. For example, white light emission may be achieved by including a variety of differently colored light-emitting dopants in one light-emitting layer, or white light emission may be achieved by separately disposing a blue light-emitting layer, a green light-emitting layer, and a red light-emitting layer in three or more stacks.

[0056] However, in the case of including a variety of light-emitting dopants in one light-emitting layer, the excitation energies required for the light-emitting dopants are different, and differences in quenching characteristics, efficiency differences, and lifetime differences among the light-emitting dopants occur during the consecutive recombination of holes and electrodes. Therefore, there is a problem that uniform white light emission is impossible.

[0057] In the case where the light-emitting layer is divided into three or more stacks, there are differences in the visibility of green light emission, red light emission, and blue light emission. Therefore, when implemented as an actual display device, there is a problem of color deterioration of a specific color. In addition, as the number of stacks increases, the process reproducibility decreases and the driving voltage increases.

[0058] As another example, by applying a yellow-green dopant to the 2-stack 2-peak structure, the color viewing angle characteristics may be excellent. However, when using a single yellow-green dopant, it is difficult to separately represent pure red and green colors. To improve the color purity, a structure of 2 stacks and 3 peaks is implemented. In addition, in this case, the phosphorescent light-emitting layer is disposed in multiple layers and it causes color variations depending on the viewing angle.

[0059] Therefore, the white light-emitting device of the present disclosure has a 2-stack 3-peak structure, thus solving the problems of deteriorated process reproducibility and increased driving voltage in a three or more stack structure due to the increased thickness of the organic stack. In addition, the blue light-emitting layer, the green light-emitting layer, and the red light-emitting layer are separately disposed in the white light-emitting device, so the reproducibility of each color can also be improved.

[0060] In addition, in the white light emitting device of the present disclosure, as Figure 3 shown in the contour map of, in the vertical distance between the second electrode 120 and the first electrode 110, the total thickness (d-Ad) of the organic material determined by summing the first laminate S1, the charge generation layer, and the second laminate S2 is relatively thin, so the position of each light emitting layer is set in a contour region having a certain inclination. This is a feature that differentiates the white light emitting device of the present disclosure from the first experimental example Ex1 of the 2-laminate 3-peak structure, in which the position of the light emitting layer is determined in a contour region having multiple inclinations. In the present disclosure, the thickness Ad of the first electrode 110 can be set to be 0.1 times or more and 0.26 times or less of the distance d from the lower surface of the first electrode 110 to the lower surface of the second electrode 120, and the distance d from the lower surface of the first electrode 110 to the lower surface of the second electrode 120 can be set to be 150 nm to 200 nm. Therefore, the inclination of the contour region is gentle in the thin structure having two laminates. Specifically, by respectively determining the positions of the blue light emitting layer, the green light emitting layer, and the red light emitting layer in a contour region having a gentle inclination, compared with the structure using multiple contour regions corresponding to different light emitting layers, multi-color interference is prevented. In addition, when the position of the blue light emitting layer is determined in a gentle contour region, this is configured such that: similar blue light intensities are generated at a certain vertical distance including the light emitting region where the blue light emitting layer is located, similar green light intensities are generated at a certain vertical distance including the light emitting region where the green light emitting layer is located, and similar red light intensities are generated at a certain vertical distance including the light emitting region where the red light emitting layer is located. Thus, even when observing the white light emitting device while tilting the white light emitting device at a predetermined angle from the front, each light emitting layer exhibits a similar light emitting color intensity, thereby preventing brightness changes due to changes in the viewing angle and preventing color deviation. This effect of preventing brightness changes and color deviation due to changes in the viewing angle is a very meaningful effect, and this effect can be obtained without increasing the processes in the structure including the red light emitting layer 141 and the green light emitting layer 142 arranged adjacent to each other.

[0061] As Figure 3As shown, the positions of each of the light-emitting layers 141, 142, and 150 are determined in regions where the light-emitting intensities of each light-emitting color are equal or similar, and interference from light emission of other colors is prevented within the thickness range of each light-emitting layer. For example, since the inclination of the contour line region for determining the position of the light-emitting layer is gentle at a distance from the second electrode, and the contour lines indicating the optimal light emission of blue, green, and red do not overlap or partially overlap with other contour lines, the blue light-emitting layer 150 is ensured to have a thickness of about 20 nm or more within the gentle contour lines, and the green light-emitting layer 142 and the red light-emitting layer 141 are ensured to be spaced downward from the blue light-emitting layer 150 in sequence. In order to have a sufficient light-emitting region in each of the light-emitting layers 142, 141, and 150, the green light-emitting layer 142 is set to have a thickness of about 20 nm or more, and the red light-emitting layer 141 is set to have a thickness of about 10 nm or more. The thicknesses of the blue light-emitting layer 150, the green light-emitting layer 142, and the red light-emitting layer 141 can all be 30 nm or less, such that the thickness between the first electrode 110 and the second electrode 120 is 150 nm or less. In addition, the distance from the upper surface of the green light-emitting layer 142 to the lower surface of the blue light-emitting layer 150 can be 30 nm to 65 nm, and the distance from the lower surface of the red light-emitting layer 141 to the upper surface of the blue light-emitting layer 150 can be 80 nm to 115 nm.

[0062] The blue light-emitting layer can have an electroluminescence peak at a wavelength of 454 nm to 458 nm, the green light-emitting layer can have an electroluminescence peak at a wavelength of 525 nm to 540 nm, and the red light-emitting layer can have an electroluminescence peak at a wavelength of 560 nm to 626 nm.

[0063] Each of the light-emitting layers 141, 142, and 150 is respectively at a position where maximum constructive interference occurs and satisfies Equation 1 below.

[0064] [Equation 1]

[0065]

[0066] ("h" is the thickness of the white organic laminate, and "z" is the distance from the second electrode to the light-emitting layer)

[0067] In the white light-emitting device of the present disclosure, considering the wavelengths of the dopants applied to the light-emitting layers 141, 142, and 150, the total optical thickness including the distance d from the lower surface of the first electrode 110 to the second electrode 120 is set in the provided white organic laminate WEL, and the positions of each light-emitting layer are determined. Each of the light-emitting layers 141, 142, and 150 includes a dopant to control its light-emitting wavelength with at least one host.

[0068] Each of the red light-emitting layer 141 and the green light-emitting layer 142 may include at least one host and a dopant for phosphorescence, and the blue light-emitting layer 150 may include at least one host and a dopant for fluorescence.

[0069] In the first stack S1, the red light-emitting layer 141 and the green light-emitting layer 142 are adjacent to each other. As Figure 3 shown, the red light-emitting layer 141 and the green light-emitting layer 142 are positioned such that respective light-emitting regions of red and green are generated in a contour line region where each color changes little according to the viewing angle. Accordingly, even when the viewing angle changes, the white light-emitting device of the present disclosure causes each of red, green, and blue to be represented in the same or similar color, thereby preventing luminance deviation and color deviation due to the change in the viewing angle.

[0070] In some cases, the first stack S1 may include a single phosphorescent light-emitting layer to represent two peaks of green and red. In this case, in the phosphorescent light-emitting layer, one or more phosphorescent dopants may have an EL peak in a wavelength range of 520 nm to 626 nm. Even in such a case where the first stack S1 has a single phosphorescent light-emitting layer, in Figure 3 the contour map, the phosphorescent light-emitting layer is also located in a region where a contour line region having the same or similar intensity with respect to the wavelength of the emission color of the phosphorescent light-emitting layer is ensured to have a certain distance from the second electrode 120 in the vertical distance. Accordingly, the occurrence of luminance deviation and color deviation due to the change in the viewing angle can be prevented.

[0071] In the white light-emitting device of the present disclosure, the blue light-emitting layer 150 is located in the second stack S2, and the red phosphorescent light-emitting layer 141 and the green phosphorescent light-emitting layer 142 are located at the first stack S1. The blue light-emitting layer 150 is located at a position higher than the red light-emitting layer 141 and the green light-emitting layer 142. This is to place the blue light-emitting layer 150 having relatively low visibility in a region having the maximum emission intensity instead of the other phosphorescent light-emitting layers 141 and 142, while setting the blue light-emitting layer 150, the red light-emitting layer 141, and the green light-emitting layer 142 in a region having the same inclination in the contour map. Thereby, without further providing an additional blue light-emitting layer in the white light-emitting device, a viewer can recognize blue, green, and red having a considerable luminance.

[0072] A charge generation layer 160 is provided between the first stack S1 and the second stack S2. For example, the charge generation layer 160 includes a stacked n-type charge generation layer 161 and a p-type charge generation layer 162.

[0073] Hereinafter, a display device using the white light-emitting device of the present disclosure and a thin film transistor array connected to the white light-emitting device may be provided.

[0074] Figure 4 is a cross-sectional view of a display device illustrating a white light emitting device including Figure 2 .

[0075] As Figure 4 shown, the display device of the present disclosure may include a substrate 100 having a plurality of sub-pixels R_SP, G_SP, B_SP, and W_SP, a white light emitting device OLED commonly provided in the sub-pixels R_SP, G_SP, B_SP, and W_SP of the substrate 100 (see Figures 1 to 3 ), a thin film transistor TFT provided in each sub-pixel and connected to a first electrode 110 of the white light emitting device OLED, and color filter layers 109R, 109G, and 109B provided under the first electrode 110 of at least one sub-pixel.

[0076] Although the display device is illustrated as including a white sub-pixel W_SP, the embodiments are not limited thereto. The white sub-pixel W_SP may be omitted, and only the red sub-pixel R_SP, the green sub-pixel G_SP, and the blue sub-pixel B_SP may be included. In some cases, the red sub-pixel, the green sub-pixel, and the blue sub-pixel may be replaced by cyan sub-pixels, magenta sub-pixels, and yellow sub-pixels capable of expressing white in combination.

[0077] The thin film transistor TFT includes, for example, a gate electrode 102, a semiconductor layer 104, a source electrode 106a connected to one side of the semiconductor layer 104, and a drain electrode 106b connected to the opposite side of the semiconductor layer 104. In addition, a channel protection layer 105 may be provided in direct contact with the upper surface of the semiconductor layer 104 to prevent damage to the channel portion of the semiconductor layer 104.

[0078] A gate insulating film 103 is provided between the gate electrode 102 and the semiconductor layer 104.

[0079] The semiconductor layer 104 may be formed of a material selected from the group consisting of amorphous silicon, polycrystalline silicon, oxide semiconductors, and combinations thereof. For example, if the semiconductor layer 104 is formed of an oxide semiconductor, the heating temperature required for forming the thin film transistor can be reduced, and the degree of freedom in using the substrate 100 is high, so that it will be advantageously applied to a flexible display device.

[0080] In addition, the drain electrode 106b of the thin film transistor TFT may be connected to the first electrode 110 in a region of a contact hole CT formed in the first protective film 107 and the second protective film 108.

[0081] A first protective film 107 is provided to mainly protect the thin film transistor TFT. The color filter layers 109R, 109G, and 109B may be provided on the first protective film 107.

[0082] When a plurality of sub-pixels SP include a red sub-pixel R_SP, a green sub-pixel G_SP, a blue sub-pixel B_SP, and a white sub-pixel W_SP, each of the first color filter layer to the third color filter layer 109R, 109G, and 109B is disposed in a corresponding sub-pixel other than the white sub-pixel W_SP among the sub-pixels, so as to transmit white light that has passed through the first electrode 110 for each wavelength. The second protective film 108 is formed under the first electrode 110 so as to cover the first color filter layer to the third color filter layer 109R, 109G, and 109B. The first electrode 110 is formed on the surface of the second protective film 108 except for a portion of the first electrode 110 formed in the contact hole CT.

[0083] Here, the white light emitting device OLED includes a white organic stack OS between a transparent first electrode 110 and a second electrode 120, the second electrode 120 being disposed opposite to the first electrode 110 and being reflective, and light being emitted through the first electrode 110. The white organic stack OS corresponds to the white organic stack WEL, which includes a phosphorescent first stack S1, a blue light emitting second stack S2, and a charge generation layer 160 between the first stack S1 and the second stack S2, as Figure 2 described therein.

[0084] The first electrode 110 is divided for each sub-pixel, and other layers of the white light emitting device OLED are integrally provided in the entire display area without any separation.

[0085] Here, reference numeral 119 denotes a bank, and the bank 119 has an opening area in a hole shape. Light emission is performed in the opening area of the bank 119. The opening area of the bank 119 defines a light emitting portion of each sub-pixel.

[0086] Here, what may be referred to as the thin film transistor array substrate 1000 includes a substrate 100, transistors TFT, and color filters 109R, 109G, and 109B.

[0087] Figure 4 The display device shown is a bottom emission type display device. However, the present disclosure is not limited to the bottom emission type display device. The display device of the present disclosure can be implemented as a top emission type display device by changing Figure 4 the shown structure such that the color filter layer is located on the second electrode 120, such that a reflective metal is included in the first electrode 110, and such that the second electrode 120 is formed as a transparent electrode or formed of a semi-transmissive metal.

[0088] Alternatively, the color filter layer may be omitted, and both the first electrode 110 and the second electrode 120 may be formed as transparent electrodes, thereby implementing a transparent organic light-emitting device.

[0089] Hereinafter, to explain the significance of the steps of the light-emitting layer of the present disclosure, a first experimental example Ex1 different from the structure of the present disclosure and a second experimental example Ex2 having the same structure as the present disclosure will be explained.

[0090] Figure 5 is a cross-sectional view illustrating the first experimental example and the second experimental example, and Figure 6 is a diagram illustrating the color deviation according to the viewing angle of the first experimental example and the second experimental example.

[0091] As Figure 5 shown, the first experimental example Ex1 includes a first electrode Anode (anode) and a second electrode Cathode (cathode), and a white organic laminate. The white organic laminate includes a first laminate S1 having a blue light-emitting layer B-EML, a second laminate S2 having a red light-emitting layer R-EML and a green light-emitting layer G-EML in contact with each other, and a charge generation layer CGL.

[0092] The second experimental example Ex2 includes a first electrode Anode (anode) and a second electrode Cathode (cathode), and a white organic laminate. The white organic laminate includes a first laminate S1 having a red light-emitting layer R-EML and a green light-emitting layer G-EML in contact with each other, a second laminate S2 having a blue light-emitting layer B-EML, and a charge generation layer CGL. The second experimental example Ex2 is a structure corresponding to Figures 1 to 3 corresponding.

[0093] The first experimental example Ex1 and the second experimental example Ex2 may further include a common layer between the light-emitting layer and the electrode.

[0094] The respective color deviations Δu'v' of the first experimental example Ex1 and the second experimental example Ex2 are evaluated by observing each EL spectrum of the first experimental example Ex1 and the second experimental example Ex2 while changing the viewing angle from 0° to 60° by 15°.

[0095] As Figure 6 shown, the first experimental example Ex1 has a large color deviation Δu'v' at viewing angles of 15° or more. Specifically, the first experimental example Ex1 exhibits a color deviation of 0.051 at a viewing angle of 50°. In contrast, the second experimental example Ex2 applying the present disclosure has a color deviation Δu'v' of less than 0.010 from a viewing angle of 0° to a viewing angle of 60°. For example, in the white light-emitting device of the second experimental example Ex2 of the present disclosure, it can be seen that each light-emitting layer in the two-laminate structure is applied to a position where the color and brightness can be maintained constant regardless of the change in the viewing angle.Figure 6 The color deviation is expressed as the change amount Δu’v’ value of the color coordinate value at a certain viewing angle compared to the color coordinate value at the front standard value of white.

[0096] It can be seen that there is almost no color change in the second experimental example Ex2 compared to the first experimental example Ex1.

[0097] This color deviation value is a characteristic that is expressed as an important specification when applied to a product, and is an important item in a display device. Compared with display devices such as LCDs and LEDs, this is also one of the important advantages of a display device including an organic light-emitting device.

[0098] Hereinafter, with reference to Table 1, the efficiency according to each color, the color deviation at a viewing angle of 50°, and the color reproduction effect of the first experimental example Ex1 and the second experimental example Ex2 are explained.

[0099] [Table 1]

[0100]

[0101] In Table 1, the color efficiency, DCI overlap rate, and BT2020 overlap rate of the first experimental example Ex1 are expressed as 100%, and the color efficiency, DCI overlap rate, and BT2020 overlap rate of the second experimental example Ex2 are evaluated by comparing with each value of the first experimental example Ex1. Table 1 shows the color efficiency of each of R, G, B, and W at each of the R, G, B, and W sub-pixels for expressing all white in the first experimental example Ex1 and the second experimental example Ex2. To express all white, in the second experimental example Ex2, the efficiency of green and white is higher than that of red and blue. In addition, Table 1 shows that to express the same all white, the second experimental example Ex2 requires a smaller efficiency of the R, G, B, and W colors than the first experimental example Ex1.

[0102] As Figure 5 and Figure 6 shown, the color deviation presented by the second experimental example Ex2 is less than 1 / 10 of the color deviation of the first experimental example Ex1, and thus there is almost no color deviation according to the viewing angle change.

[0103] DCI represents Digital Cinema Initiatives that can be expressed in digital movies. BT2020 is the 4K UHD standard recommended by the ITU international broadcasting standards organization, also known as Rec.2020. The standard applied in BT2020 is more stringent than the standard applied in DCI, and the color expression area of BT2020 is larger than the color expression area of DCI.

[0104] Table 1 shows that the second experimental example Ex2 has a color reproduction equal to or higher than that of the first experimental example Ex1. This means that the second experimental example Ex2 achieves a more accurate and clear image than the first experimental example Ex1.

[0105] The white light emitting device is considered from the perspective of a display device. The display device may include a white sub-pixel, a red sub-pixel, a green sub-pixel, and a blue sub-pixel that emit white light, red light, green light, and blue light, respectively. The aperture ratio and driving power defined by the opening area of the bank portion 119 of Figure 4 can be determined in consideration of the efficiency, lifetime, and color coordinates of each sub-pixel. In addition, the relative color difference in the sub-pixel can be compensated by controlling the aperture ratio and driving power.

[0106] Hereinafter, as a structure for realizing three peaks, the first experimental example Ex1 and the second experimental example Ex2 each having two stacked bodies and the third experimental example Ex3 having three stacked bodies described above are further explained.

[0107] Figures 7A to 7C is a contour map illustrating the first to third experimental examples.

[0108] As Figure 7A shown, in the first experimental example Ex1 having two stacked bodies, a blue light emitting layer B-EML is provided in the first stacked body and a red light emitting layer R-EML and a green light emitting layer G-EML are provided in the second stacked body. The total vertical distance from the lower surface of the first electrode Anode to the lower surface of the second electrode Cathode is to The first experimental example Ex1 requires a thicker vertical distance from the lower surface of the first electrode to the lower surface of the second electrode. Since the thickness of the first electrode is thicker, it is above, and the light-emitting regions of the blue light-emitting layer B-EML are set at different first contour regions C1 and second contour regions C2 from those of the red light-emitting layer R-EML and the green light-emitting layer G-EML. The contour regions C1 and C2 each have the maximum intensity of each laminate, so that the optical distance is substantially formed over a wide distance in the first experimental example Ex1. Since the third contour region C3 does not present a sufficient vertical distance to set a light-emitting layer of any light-emitting color, the blue light-emitting layer B-EML of the first laminate as the first light emission is away from the first electrode. This means that the thickness of the common layer between the first electrode Anode and the blue light-emitting layer B-EML is very thick, resulting in an increase in the overall thickness of the white organic laminate. In addition, in the first experimental example Ex1, since the inclination of the second contour region C2 where the blue light-emitting layer B-EML is located is different from the inclination of the first contour region C1 where the red light-emitting layer R-EML and the green light-emitting layer G-EML are located, when the viewing angle changes, the color deviation of blue is different from the color deviations of red and green. This causes color deviation and brightness difference according to the change in the viewing angle.

[0109] In a second experimental example Ex2 according to Figures 1 to 3 , as Figure 7B shown, the red light-emitting layer R-EML and the green light-emitting layer G-EML are set in the first laminate and the blue light-emitting layer B-EML is set in the second laminate. The total vertical distance d from the lower surface of the first electrode Anode to the lower surface of the second electrode Cathode is to (= 150 nm to 200 nm). Although the second experimental example Ex2 has two laminates, since the blue light-emitting layer B-EML, the green light-emitting layer G-EML, and the red light-emitting layer R-EML are set in the contour region C1 having a single inclination, the total vertical distance d of the second experimental example Ex2 is less than half of the total vertical distance of the first experimental example Ex1.

[0110] In addition, the thickness of the first electrode in the second experimental example Ex2 is less than half of the thickness of the first electrode in the first experimental example Ex1.

[0111] For example, the second experimental example Ex2 can provide a white organic laminate WEL having a thickness of or less and a first electrode having a thickness of 0.1 times or more and 0.26 times or less of the distance from the lower surface of the first electrode to the lower surface of the second electrode. In this case, compared with the thickness of the first electrode being Compared with the first experimental example Ex1 above, the thickness of the first anode in the second experimental example Ex2 can be half or less of that in Ex1. Additionally, the ratio of the thickness of the first electrode 110 with an optical effect to the distance d from the lower surface of the first electrode 110 to the lower surface of the second electrode 120 is less than that in the first experimental example Ex1, so the transmittance of light passing through the first electrode 110 from the white organic laminate WEL can be increased. In the second experimental example Ex2, the blue emission layer B-EML, the green emission layer G-EML, and the red emission layer R-EML are disposed at the contour line region C1 with a single inclination, and this single inclination is gentle at the contour line region C1. Among the vertical distance d from the lower surface of the first electrode 110 to the lower surface of the second electrode 120, the blue emission region B-EMZ, the green emission region G-EMZ, and the red emission region R-EMZ of the blue emission layer, the green emission layer, and the red emission layer (as Figure 1 shown) can be ensured within a certain vertical distance. Therefore, even when the viewer tilts the display device at a certain viewing angle while viewing the display device, the same color can be perceived without any color change or brightness change compared with viewing the front of the display device.

[0112] As Figure 7C shown, the third experimental example Ex3 has three laminates and realizes three peaks. In the third experimental example Ex3, the first blue emission layer B1-EML is disposed in the first laminate, the red emission layer R-EML and the green emission layer G-EML are disposed in the second laminate, and the second blue emission layer B2-EML is disposed in the third laminate. The third experimental example Ex3 aims to improve the blue light efficiency. The total vertical distance from the lower surface of the first electrode Anode to the lower surface of the second electrode Cathode is to The third experimental example, Ex3, requires an additional laminate compared to the first experimental example, Ex1, and the second experimental example, Ex2, and the thickness of the first electrode, Anode, is relatively thick, similar to the thickness of the first electrode in the first experimental example, Ex1. In the third experimental example, Ex3, the first to fourth isoconcentration regions, C1, C2, C3, and C4, have different inclinations from each other. For the first to fourth isoconcentration regions, the first blue emission layer, B1-EML, is disposed in the third isoconcentration region, C3, the red emission layer, R-EML, and the green emission layer, G-EML, are disposed in the second isoconcentration region, C2, and the second blue emission layer, B2-EML, is disposed in the first isoconcentration region, C1. For the same reason as in the first experimental example, Ex1, the third experimental example, Ex3, requires an increase in the thickness corresponding to the vertical distance from the lower surface of the first electrode to the lower surface of the second electrode and an increase in the thickness of the common layer between the first electrode and the first blue emission layer, and as the number of laminates increases, the processability is also reduced and the driving voltage is increased. In addition, since the emission layers, B1-EML, R-EML, G-EML, and B2-EML, disposed in the first to third laminates are located in the isoconcentration regions, C3, C2, and C1, having different inclinations, the deviation of blue according to the viewing angle change is different from the deviation of red and green according to the viewing angle change. As the viewing angle becomes larger, this different tendency of colors according to the viewing angle results in a large color deviation.

[0113] For example, comparing the vertical distances from the lower surface of the first electrode to the lower surface of the second electrode in the first to third experimental examples, Ex1 to Ex3, the vertical distance of the first experimental example, Ex1, exceeds twice the vertical distance of the second experimental example, Ex2, and the vertical distance of the third experimental example, Ex3, exceeds 2.5 times the vertical distance of the second experimental example, Ex2. Therefore, the first experimental example, Ex1, and the third experimental example, Ex3, may have problems of high process burden and increased driving voltage.

[0114] In addition, since the first experimental example, Ex1, and the third experimental example, Ex3, use emission layers disposed in different isoconcentration regions having different inclinations for multiple laminates, the first experimental example, Ex1, and the third experimental example, Ex3, have different tendencies according to the viewing angle for multiple laminates, and there are problems of color deviation and brightness change when the viewing angle changes. In contrast, in the second experimental example, Ex2, the emission layer is disposed in the isoconcentration region having a single inclination, and thus the second experimental example, Ex2, can overcome the color deviation and brightness change when the viewing angle changes.

[0115] Hereinafter, the effects of the present disclosure will be explained.

[0116] Figure 8 is a graph showing the light intensity according to wavelength of the white light emitting device of the present disclosure. Figure 9It is a graph of the light intensity according to wavelength for each viewing angle of, for example, the white light emitting device of the present disclosure. Figure 10 It is a graph illustrating the color deviation according to the viewing angle of the present disclosure. Figure 11 It is a graph illustrating the J-V curve in the white light emitting device of the present disclosure.

[0117] As Figure 8 shown, the white light emitting device of the present disclosure can achieve three peaks representing the emission peak characteristics of blue, green, and red.

[0118] In addition, as Figure 9 shown, referring to the EL spectrum of the white light emitting device of the present disclosure while changing the viewing angle from 0° to 60° from the front, it can be seen that the intensity of each emission color hardly changes. For example, even when the viewing angle changes, the white light emitting device according to the present disclosure exhibits the same color and the same brightness characteristics.

[0119] Figure 10 It shows the color deviation value Δu’v’ according to the viewing angle change from the front to 60° while changing the viewing angle from 0° to 15°. In Figure 10 it, the vertical axis is magnified for easy understanding. Basically, in the present disclosure, the color deviation value Δu’v’ at a 60° viewing angle is less than or equal to 0.005, which is 0.1 times or less of the color deviation value of the above-mentioned first experimental example Ex1. It can be seen that in the present disclosure, the color deviation according to the viewing angle change is negligible.

[0120] As Figure 11 shown, the white light emitting device of the present disclosure exhibits a current density of 10 mA / cm 2 or more at a driving voltage of 7 V or more, which indicates that the white light emitting device of the present disclosure has achieved a stable device with a current density above a certain level at a predetermined driving voltage.

[0121] In the present disclosure, since the thickness of the white light emitting device is thin, the thickness of the charge generation layer between the first laminate S1 and the second laminate S2 is very thin. The total thickness of the charge generation layer ( Figure 2 in 160) is to The charge generation layer 160 may include an n-type charge generation layer and a p-type charge generation layer.

[0122] If the thickness of the charge generation layer 160 is less than then the white light emitting device may not have sufficient lifespan. If the thickness of the charge generation layer 160 is greater than then it is difficult to have different common layers between the light emitting region G-EMZ of the green light emitting layer and the light emitting region B-EMZ of the blue light emitting layer. Therefore, the thickness of the charge generation layer 160 is greater than or equal to and less than or equal to

[0123] Hereinafter, with reference to the first experimental example Ex1, the second experimental example Ex2, and the fourth experimental example Ex4, the characteristics of the driving voltage according to the thickness of the charge generation layer will be explained. The fourth experimental example Ex4 has the same structure as the second experimental example Ex2, and a red light-emitting layer and a green light-emitting layer are provided in the first laminate, and a blue light-emitting layer is provided in the second laminate.

[0124] [Table 2]

[0125]

[0126] As described above, the second experimental example Ex2 has the total thickness of the thin first electrode and the thin white organic laminate. Therefore, compared with the first experimental example Ex1, the second experimental example Ex2 can increase the productivity and reduce the driving voltage. In addition, in the second experimental example Ex2, there is almost no color deviation according to the change in viewing angle. In the above experiment based on Table 2, in the second experimental example Ex2, the total thickness of the charge generation layer including the n-type charge generation layer and the p-type charge generation layer is

[0127] In the fourth experimental example Ex4, the total thickness of the charge generation layer including the n-type charge generation layer and the p-type charge generation layer is It can be seen that, compared with the second experimental example Ex2, in the fourth experimental example Ex4, the driving voltage increases and the color coordinate characteristics change. For example, the red light-emitting layer and the green light-emitting layer of the first laminate and the blue light-emitting layer of the second laminate are provided in the contour line region having a single inclination. Therefore, in the white light-emitting device according to the present disclosure, the distance from the green light-emitting layer to the blue light-emitting layer is very short. Therefore, as a common layer, the thickness of the charge generation layer located between the green light-emitting layer and the blue light-emitting layer is less than or equal to and greater than or equal to The driving voltage can be reduced and color deviation or brightness change can be reduced or prevented.

[0128] Figure 12 is a graph showing the 95 lifetimes of the second and fourth experimental examples of the white light-emitting device. Figure 13 is a graph showing the driving voltage deviation according to time in the first and second experimental examples. Figure 14 is a graph showing the color temperature deviation according to time in the white light-emitting device of the present disclosure. Hereinafter, the white light-emitting device and the display device of the present disclosure will be explained with reference to the drawings.

[0129] With reference to Figure 12The results of evaluating the 95 - life at a 95% brightness level relative to the initial brightness, as shown, show that the second experimental example Ex2 and the fourth experimental example Ex4 exhibit similar trends in their lifetimes. Generally, the second experimental example Ex2 is superior to the fourth experimental example Ex4, which means that the thickness of the charge - generating layer needs to be ensured to be above a certain level.

[0130] As a reference time for checking the lifetime of the device under accelerated conditions, the time at 100% presented in Figures 12 to 14 the experimental example can be several hundred hours.

[0131] As a result of evaluating the driving voltage ΔV with respect to time for the first experimental example Ex1 (refer to Figure 7A ) and the second experimental example Ex2 (refer to Figure 7B ), it can be seen that the change in the driving voltage of the second experimental example Ex2 is less than that of the first experimental example Ex1. For example, in the structure of the second experimental example Ex2 of the present disclosure, the driving voltage hardly changes over time, so this represents the driving stability in the present disclosure.

[0132] Figure 14 Shows the change in the color temperature ΔCCT over time in the present disclosure. In Figure 14 , the time at 100% refers to the time for evaluating the normal level of the color temperature, which corresponds to several hundred hours. It shows that even after several hundred hours, the change in the color temperature is less than 300K, so it can be seen that even after a certain period of time, the color temperature characteristics at the initial level are still exhibited.

[0133] For example, through the above experiments, it can be said that the change in the driving voltage is very small, ensuring an increased lifetime and stably ensuring the color temperature characteristics.

[0134] When applying a white organic laminate in a display device, it is necessary to adjust the color temperature to a certain level. Considering this, an additional laminate is required and the driving voltage increases due to the increase in the thickness of the white organic laminate. In addition, due to the increase in the driving voltage, the panel application performance may be reduced. The white - light emitting device and the display device according to the present disclosure can solve such problems. For example, the white - light emitting device and the display device according to the present disclosure can adjust the color temperature to a certain level, comprehensively match the color - viewing - angle characteristics, the brightness - degradation rate, and the color - reproduction rate, thus stabilizing the color - viewing - angle characteristics generated in the multi - laminate structure, maintaining the color - temperature and the dominant - wavelength characteristics, and additionally preventing the brightness reduction according to the viewing angle.

[0135] The white light emitting device of the present disclosure is a device having three peaks of red, green, and blue. For example, it can be seen that in the white light emitting device of the present disclosure, for each of red light, green light, and blue light, the intensity change is very small and the brightness does not decrease. In other words, it shows an equal level in all directions, and in view of this trend, the white light emitting device according to the present disclosure and the display device using the white light emitting device seem to be applicable to a new generation model.

[0136] In addition, the white light emitting device of the present disclosure can be enlarged. The viewing angle range required for a large area display device is wide. In the white light emitting device and the display device of the present disclosure, the same brightness and color efficiency are exhibited under the above wide viewing angle range, so that good characteristics suitable for being viewed by many viewers in a wide space are exhibited. In addition, since the structure is also simple, its application range is expected to be diversified. The intensity of each peak hardly changes, so the same image can be displayed in any direction.

[0137] Furthermore, the white light emitting device of the present disclosure optimizes the optical distance and position of the light emitting region of the light emitting layer by adjusting the vertical distance between the light emitting layers in different laminates related to the isocontour region having a single inclination, so that the display device having the white light emitting device of the present disclosure has a small color deviation and brightness change regardless of the viewing angle change.

[0138] The layer stacking order and the optical distance are reconstructed according to the double laminate structure of the present disclosure to limit the thickness range of the first electrode, the overall thickness of the organic materials in the white organic laminate, and the position of the light emitting layer. Therefore, there is almost no color deviation according to the viewing angle, and the brightness and color characteristics are the same in all directions without brightness reduction. Thus, the application can be extended to products for IT and display devices.

[0139] For example, a white light emitting device according to an embodiment of the present disclosure may include: a first laminate on a first electrode, the first laminate including a red light emitting layer and a green light emitting layer; a charge generation layer on the first laminate; a second laminate on the charge generation layer, the second laminate including a blue light emitting layer; and a second electrode on the second laminate, wherein light is emitted through the first electrode, and wherein the thickness of the first electrode is 0.1 times or more and 0.26 times or less of the distance from the lower surface of the first electrode to the lower surface of the second electrode.

[0140] The distance from the lower surface of the first electrode to the lower surface of the second electrode may be 150 nm to 200 nm.

[0141] The blue light-emitting layer may have an electroluminescence peak at a wavelength of 454 nm to 458 nm, the green light-emitting layer may have an electroluminescence peak at a wavelength of 525 nm to 540 nm, and the red light-emitting layer may have an electroluminescence peak at a wavelength of 560 nm to 626 nm.

[0142] Each of the blue light-emitting layer and the green light-emitting layer may be thicker than the red light-emitting layer.

[0143] The charge generation layer may be thinner than the red light-emitting layer.

[0144] The white light-emitting device may further include: a first common layer between the first electrode and the red light-emitting layer; a second common layer between the green light-emitting layer and the charge generation layer; a third common layer between the charge generation layer and the blue light-emitting layer; and a fourth common layer between the blue light-emitting layer and the second electrode. The red light-emitting layer may be in contact with the green light-emitting layer.

[0145] The distance from the upper surface of the green light-emitting layer to the lower surface of the blue light-emitting layer may be 30 nm to 65 nm.

[0146] A display device according to an embodiment of the present disclosure may include: a substrate including a plurality of sub-pixels; a thin-film transistor at each sub-pixel; a first electrode connected to the thin-film transistor at each sub-pixel in the sub-pixels; a white organic laminate on the first electrode, the white organic laminate including a first laminate including a red light-emitting layer and a green light-emitting layer, a second laminate including a blue light-emitting layer, and a charge generation layer between the first laminate and the second laminate; and a second electrode on the white organic laminate. Light may be emitted from the white organic laminate through the first electrode. The thickness of the first electrode may be 0.1 times or more and 0.26 times or less of the total thickness of the first electrode and the white organic laminate.

[0147] A display device according to an embodiment of the present disclosure may further include a color filter between the substrate and the first electrode.

[0148] In the display device of the present disclosure, the first electrode may be a transparent electrode, and the second electrode may be a reflective electrode.

[0149] In the display device of the present disclosure, the distance from the lower surface of the first electrode to the lower surface of the second electrode may be 150 nm to 200 nm.

[0150] In the display device of the present disclosure, the blue light-emitting layer may have an electroluminescence peak at a wavelength of 454 nm to 458 nm, the green light-emitting layer may have an electroluminescence peak at a wavelength of 525 nm to 540 nm, and the red light-emitting layer may have an electroluminescence peak at a wavelength of 560 nm to 626 nm.

[0151] In the display device of the present disclosure, each of the blue light-emitting layer and the green light-emitting layer may be thicker than the red light-emitting layer.

[0152] In the display device of the present disclosure, the charge generation layer may be thinner than the red light-emitting layer.

[0153] The display device of the present disclosure further includes: a first common layer between the first electrode and the red light-emitting layer; a second common layer between the green light-emitting layer and the charge generation layer; a third common layer between the charge generation layer and the blue light-emitting layer; and a fourth common layer between the blue light-emitting layer and the second electrode. The red light-emitting layer may be in contact with the green light-emitting layer.

[0154] In the display device of the present disclosure, the distance from the upper surface of the green light-emitting layer to the lower surface of the blue light-emitting layer may be 30 nm to 65 nm.

[0155] In the display device of the present disclosure, the distance from the lower surface of the red light-emitting layer to the upper surface of the blue light-emitting layer may be 80 nm to 115 nm.

[0156] The white light-emitting device of the present disclosure designates the positions of the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer, and adjusts the thickness of the first electrode according to a constant relationship with the total thickness of the first electrode and the white organic laminate, so that even when the viewing angle changes, the spectrum of each light can be maintained the same or similar to that of the front, while setting the light-emitting regions of each light-emitting layer in an isoconcentration region having the same gentle inclination. Since there is no color change according to the viewing angle change, it is advantageous to apply the white light-emitting device of the present disclosure to a display device. In particular, since almost no viewing angle change occurs in all directions, when applied to a large area, excellent color characteristics can be exhibited without color difference even when viewed by many viewers.

[0157] In addition, the white light-emitting device and the display device of the present disclosure do not cause brightness deviation according to the change of the viewing angle, and the same image can be realized at a wide viewing angle.

[0158] Furthermore, the white light-emitting device and the display device of the present disclosure can achieve three peaks in the white organic laminate with the smallest structure, so that the driving voltage can be reduced and the processability can be improved at the same time.

[0159] It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to cover these modifications and variations of the present disclosure as long as they fall within the scope of the appended claims and their equivalents.

[0160] This application claims the benefit of Korean Patent Application No. 10-2020-0183936, filed on Dec. 24, 2020, which is incorporated herein by reference in its entirety as if fully set forth herein.

Claims

1. A white light emitting device, the white light emitting device comprising: A first stack, the first stack being on a first electrode, the first stack comprising a red light emitting layer and a green light emitting layer; A charge generation layer, the charge generation layer being on the first stack; A second stack, the second stack being on the charge generation layer, the second stack comprising a blue light emitting layer; and A second electrode, the second electrode being on the second stack, wherein light is emitted through the first electrode, wherein the thickness of the first electrode is 0.1 times or more and 0.26 times or less of the distance from the lower surface of the first electrode to the lower surface of the second electrode, and wherein the distance from the lower surface of the first electrode to the lower surface of the second electrode is 150 nm to 200 nm.

2. The white light emitting device according to claim 1, wherein, The blue light emitting layer, the green light emitting layer, and the red light emitting layer are located in a single contour line region of a contour map, wherein the contour map is a map of luminance calculated based on the wavelength of the emitted light and the distance from the second electrode.

3. The white light emitting device according to claim 1, wherein, The green light emitting layer is disposed on the red light emitting layer.

4. The white light emitting device according to claim 1, wherein, The blue light emitting layer has an electroluminescence peak at a wavelength of 454 nm to 458 nm, The green light emitting layer has an electroluminescence peak at a wavelength of 525 nm to 540 nm, and The red light emitting layer has an electroluminescence peak at a wavelength of 560 nm to 626 nm.

5. The white light emitting device according to claim 1, wherein, Each of the blue light emitting layer and the green light emitting layer is thicker than the red light emitting layer.

6. The white light emitting device according to claim 5, wherein, The charge generation layer is thinner than the red light emitting layer.

7. The white light emitting device according to claim 1, the white light emitting device further comprising: A first common layer, the first common layer being between the first electrode and the red light emitting layer; A second common layer, the second common layer being between the green light emitting layer and the charge generation layer; A third common layer, the third common layer being between the charge generation layer and the blue light emitting layer; and A fourth common layer, the fourth common layer being between the blue light emitting layer and the second electrode, wherein the red light emitting layer is in contact with the green light emitting layer.

8. The white light emitting device according to claim 1, wherein, The distance from the upper surface of the green light emitting layer to the lower surface of the blue light emitting layer is 30 nm to 65 nm.

9. The white light emitting device according to claim 1, wherein, The charge generation layer includes an n-type charge generation layer and a p-type charge generation layer, and has a thickness of 6 nm to 15 nm.

10. The white light emitting device according to claim 1, wherein, The thickness of the charge generation layer is 6 nm to 13 nm.

11. The white light emitting device according to claim 1, wherein, The thickness of each of the blue light emitting layer and the green light emitting layer is equal to or greater than 20 nm, and the thickness of the red light emitting layer is equal to or greater than 10 nm.

12. A display device, the display device comprising: A substrate, the substrate including a plurality of sub-pixels; A thin film transistor, the thin film transistor being at each of the sub-pixels; A first electrode, the first electrode being connected to the thin film transistor at each of the sub-pixels; A white organic laminate, the white organic laminate being on the first electrode, the white organic laminate including a first laminate including a red light-emitting layer and a green light-emitting layer, a second laminate including a blue light-emitting layer, and a charge generation layer between the first laminate and the second laminate; And A second electrode, the second electrode being on the white organic laminate, wherein light is emitted from the white organic laminate through the first electrode, wherein the thickness of the first electrode is 0.1 times or more and 0.26 times or less of the total thickness of the first electrode and the white organic laminate, and wherein the distance from the lower surface of the first electrode to the lower surface of the second electrode is 150 nm to 200 nm.

13. The display device according to claim 12, wherein, The blue light-emitting layer, the green light-emitting layer, and the red light-emitting layer are located in a single contour line region of the contour map in the white organic laminate, wherein the contour map is a map of the luminous intensity calculated based on the wavelength of the emitted light and the distance from the second electrode.

14. The display device according to claim 12, wherein, In the first laminate, the green light-emitting layer is disposed on the red light-emitting layer.

15. The display device according to claim 12, the display device further including a color filter, the color filter being between the substrate and the first electrode.

16. The display device according to claim 12, wherein, The first electrode is a transparent electrode, and the second electrode is a reflective electrode.

17. The display device according to claim 12, wherein, the blue light-emitting layer has an electroluminescence peak at a wavelength of 454 nm to 458 nm, the green light-emitting layer has an electroluminescence peak at a wavelength of 525 nm to 540 nm, and the red light-emitting layer has an electroluminescence peak at a wavelength of 560 nm to 626 nm.

18. The display device according to claim 12, wherein Each of the blue light-emitting layer and the green light-emitting layer is thicker than the red light-emitting layer.

19. The display device according to claim 18, wherein, The charge generation layer is thinner than the red light-emitting layer.

20. The display device according to claim 12, wherein, The white organic laminate further includes: a first common layer, the first common layer being between the first electrode and the red light-emitting layer; a second common layer, the second common layer being between the green light-emitting layer and the charge generation layer; a third common layer, the third common layer being between the charge generation layer and the blue light-emitting layer; and a fourth common layer, the fourth common layer being between the blue light-emitting layer and the second electrode, wherein the red light-emitting layer is in contact with the green light-emitting layer.

21. The display device according to claim 12, wherein, The distance from the upper surface of the green light-emitting layer to the lower surface of the blue light-emitting layer is 30 nm to 65 nm.

22. The display device according to claim 21, wherein, The distance from the lower surface of the red light-emitting layer to the upper surface of the blue light-emitting layer is 80 nm to 115 nm.

23. The display device according to claim 12, wherein, The charge generation layer includes an n-type charge generation layer and a p-type charge generation layer, and has a thickness of 6 nm to 15 nm.

24. The display device according to claim 12, wherein The thickness of the charge generation layer is 6 nm to 13 nm.

25. The display device according to claim 12, wherein, The thickness of each of the blue light-emitting layer and the green light-emitting layer is equal to or greater than 20 nm, and the thickness of the red light-emitting layer is equal to or greater than 10 nm.

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