Organic Light-Emitting Display Device

Abstract

An organic light emitting display device is provided. The organic light emitting display device includes a first sub-pixel, a second sub-pixel, and a third sub-pixel configured to emit lights of different colors. The organic light emitting display device includes: a substrate; a first pixel electrode to a third pixel electrode; a first organic emission layer configured to emit light having a first wavelength; a second organic emission layer configured to emit light having a second wavelength; a third organic emission layer configured to emit light having a third wavelength; a counter electrode; a cover layer located on the counter electrode and having a refractive index with respect to the first wavelength that is at least 7% higher than the refractive index with respect to the second wavelength; and a thin film encapsulation layer located on the cover layer.

Description

[0001] This application is a divisional application of the invention patent application "organic light-emitting display device" with an application date of August 1, 2018 and an application number of 201810861913.0. Technical Field

[0002] One or more embodiments relate to an organic light-emitting display device, and more particularly, to an organic light-emitting display device including a cover layer and a thin film encapsulation layer. Background Art

[0003] An organic light-emitting display device includes an organic light-emitting device (OLED), the organic light-emitting device including a hole injection electrode, an electron injection electrode, and an organic emission layer formed therebetween, and the organic light-emitting display device is a self-emitting type display device that generates light when excitons transition from an excited state to a ground state, wherein when holes injected from the hole injection electrode and electrons injected from the electron injection electrode combine in the organic emission layer, excitons are generated.

[0004] Here, a cover layer may be provided above the OLED to improve the light emission efficiency of the organic light-emitting display device.

[0005] Recently, research has been actively conducted to implement an organic light-emitting display device as a flexible display device, and the flexible display device may include a flexible substrate and a flexible protective layer that protects the OLED. Therefore, the light emitted from the OLED is affected by the characteristics of the cover layer and the flexible protective layer.

[0006] Structures for improving light efficiency by introducing a microcavity into an organic light-emitting display device have been proposed. In a top-emission type OLED, the pixel electrode of the top-emission OLED may be a reflective electrode, and the counter electrode facing the pixel electrode may be a semi-transmissive electrode. Summary of the Invention

[0007] One or more embodiments include an organic light-emitting display device having high light efficiency and color deviation as a function of viewing angle in a direction where color deviation is not easily noticeable to a user.

[0008] Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the given embodiments.

[0009] According to one or more embodiments, an organic light-emitting display device includes a first sub-pixel, a second sub-pixel, and a third sub-pixel configured to emit lights of different colors. The organic light-emitting display device includes: a substrate including a first region to a third region corresponding to the first sub-pixel to the third sub-pixel respectively; a first pixel electrode to a third pixel electrode located in the first region to the third region of the substrate respectively; a first organic emission layer located on the first pixel electrode and configured to emit light having a first wavelength; a second organic emission layer located on the second pixel electrode and configured to emit light having a second wavelength, the second wavelength being longer than the first wavelength; a third organic emission layer located on the third pixel electrode and configured to emit light having a third wavelength, the third wavelength being longer than the second wavelength; a counter electrode covering the first organic emission layer to the third organic emission layer; a cover layer located on the counter electrode and having a refractive index with respect to the first wavelength that is at least 7% higher than the refractive index with respect to the second wavelength; and a thin film encapsulation layer located on the cover layer.

[0010] The refractive index of the cover layer with respect to the third wavelength may be at least 3% smaller than the refractive index with respect to the second wavelength.

[0011] The first organic emission layer to the third organic emission layer may be respectively configured to emit blue light, green light, and red light, and the first wavelength to the third wavelength may be 460 nm, 530 nm, and 620 nm respectively.

[0012] The cover layer may have a refractive index with respect to the second wavelength of 1.9 to 2.3.

[0013] The cover layer may be continuously provided throughout the first sub-pixel to the third sub-pixel, and the thickness of the cover layer may be substantially uniform.

[0014] The thickness of the cover layer may be to

[0015] The thin film encapsulation layer may include a first encapsulation inorganic film, an encapsulation organic film located on the first encapsulation inorganic film, and a second encapsulation inorganic film located on the encapsulation organic film.

[0016] The first encapsulation inorganic film may include a first lower encapsulation inorganic film contacting the cover layer and a first upper encapsulation inorganic film located on the first lower encapsulation inorganic film.

[0017] The first lower encapsulation inorganic film may include lithium fluoride (LiF).

[0018] The refractive index (n e ) of the counter electrode, the refractive index (n c ) of the cover layer, the refractive index (n1) of the first lower encapsulation inorganic film, the refractive index (n2) of the first upper encapsulation inorganic film, and the refractive index (n3) of the encapsulation organic film may satisfy the condition nc >n2>n3>n1>n e 。

[0019] The resonance efficiency of the first sub-pixel can be at least 50% higher than that of the second and third sub-pixels.

[0020] The organic light-emitting display device may further include: a first lower functional layer located between the first pixel electrode and the first organic emission layer; a second lower functional layer located between the second pixel electrode and the second organic emission layer; and a third lower functional layer located between the third pixel electrode and the third organic emission layer, wherein the first to third lower functional layers may have different thicknesses.

[0021] The refractive index of the cover layer with respect to the first wavelength may be 8% to 15% higher than the refractive index of the cover layer with respect to the second wavelength.

[0022] According to one or more embodiments, an organic light-emitting display device includes a first sub-pixel, a second sub-pixel, and a third sub-pixel configured to emit light of different colors. The organic light-emitting display device includes: a first pixel electrode to a third pixel electrode respectively located in the first sub-pixel to the third sub-pixel; a first organic emission layer disposed on the first pixel electrode and configured to emit blue light including a first wavelength; a second organic emission layer located on the second pixel electrode and configured to emit green light including a second wavelength, the second wavelength being longer than the first wavelength; a third organic emission layer located on the third pixel electrode and configured to emit red light including a third wavelength, the third wavelength being longer than the second wavelength; a counter electrode continuously disposed on the first organic emission layer to the third organic emission layer; and a cover layer located on the counter electrode, continuously covering the entire first sub-pixel to the third sub-pixel with a substantially uniform thickness, and having a refractive index with respect to the first wavelength that is at least 7% higher than the refractive index with respect to the second wavelength.

[0023] The organic light-emitting display device may further include a thin film encapsulation layer located on the cover layer in contact with the cover layer.

[0024] The thin film encapsulation layer may include a first lower encapsulation inorganic film, a first upper encapsulation inorganic film, an encapsulation organic film, and a second encapsulation inorganic film sequentially disposed.

[0025] The refractive indices of the first lower encapsulation inorganic film, the first upper encapsulation inorganic film, the encapsulation organic film, and the second encapsulation inorganic film may be 1.35 to 1.45, 1.7 to 1.85, 1.45 to 1.55, and 1.7 to 1.85, respectively.

[0026] The refractive index of the cover layer with respect to the third wavelength may be at least 3% smaller than the refractive index with respect to the second wavelength.

[0027] The cover layer may have a refractive index relative to the second wavelength of 1.9 to 2.3.

[0028] The thickness of the cover layer may be to BRIEF DESCRIPTION OF THE DRAWINGS

[0029] These and / or other aspects will become apparent and more readily appreciated from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0030] Figure 1 is a cross-sectional view of an organic light emitting display device according to an embodiment;

[0031] Figure 2 is Figure 1 a cross-sectional view of a stacked structure of a first sub-pixel, a second sub-pixel, and a third sub-pixel;

[0032] Figure 3A is a graph of the light extraction efficiency in the first sub-pixel to the third sub-pixel when the refractive index of the cover layer is the same at the first wavelength to the third wavelength, Figure 3B is a graph of the light extraction efficiency in the first sub-pixel to the third sub-pixel when the condition that the refractive index at the first wavelength > the refractive index at the second wavelength > the refractive index at the third wavelength is satisfied;

[0033] Figure 4 is a graph of the refractive index of the cover layer as a function of wavelength included in the embodiment;

[0034] Figure 5 is a comparison example of the cover layer and Figure 4 a table of the refractive indices of the cover layer of

[0035] Figure 6A and Figure 6B are graphs of color deviation as a function of viewing angle in the ultraviolet (UV) coordinate system in the comparison example and the example (CPLf) of Figure 5 respectively;

[0036] Figures 7A to 7D is a graph of the resonance efficiency and light absorption rate as a function of wavelength according to Example 1 to Example 3 and the comparison example;

[0037] Figure 8 is a cross-sectional view of a cover layer and a thin film encapsulation layer according to another embodiment; and

[0038] Figure 9 is a cross-sectional view of a cover layer and a thin film encapsulation layer according to another embodiment. DETAILED DESCRIPTION

[0039] Since the present disclosure permits various suitable changes and many embodiments, specific embodiments will be shown in the drawings and described in detail in the written description. In this regard, the embodiments given may have different forms and should not be construed as limited to the description set forth herein. Accordingly, the embodiments are described below only for purposes of explaining aspects of the present specification by referring to the drawings.

[0040] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. When expressions such as "at least one of...", "one of...", and "selected from..." are placed after a list of elements, they modify the entire list of elements, rather than individual elements of the list. Further, when the term "may" is used in describing embodiments of the present invention, it means "one or more embodiments of the present invention". Additionally, the term "exemplary" means an example or illustration.

[0041] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer, or part from another. Thus, a first element, component, region, layer, or part discussed below may be named a second element, component, region, layer, or part without departing from the spirit and scope of the present invention.

[0042] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the present invention. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context clearly dictates otherwise.

[0043] It will also be understood that when the terms "comprises" and "comprising" and their variations are used in this specification, they specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0044] It will be understood that when an element or layer is referred to as being "on", "connected to", "coupled to", "connected with", "coupled with" or "adjacent to" another element or layer, the element or layer can be "directly on", "directly connected to", "directly coupled to", "directly connected with", "directly coupled with" or "directly adjacent to" the other element or layer, or there can be one or more intermediate elements or layers. Further, "connected" and its variations etc. can also refer to "electrically connected" and its variations etc., depending on the context in which these terms are used as will be understood by those skilled in the art. When an element or layer is referred to as being "directly on", "directly connected to", "directly coupled to", "directly connected with", "coupled with" or "immediately adjacent to" another element or layer, there are no intermediate elements or intermediate layers.

[0045] Features described with respect to one or more embodiments of the present invention can be used in combination with features of other embodiments of the present invention. For example, features described in a first embodiment can be combined with features described in a second embodiment to form a third embodiment, even if the third embodiment may not be specifically described herein.

[0046] For ease of explanation, the dimensions of the elements (or components) in the drawings may be exaggerated. In other words, since the dimensions and thicknesses of the components in the drawings are arbitrarily shown for ease of explanation, the following embodiments are not limited thereto.

[0047] For ease of description, spatial relative terms such as "top", "bottom", "beneath", "below", "lower", "under", "above", "upper", etc. may be used herein to describe the relationship of one element or feature to another (other) element or feature as shown in the drawings. It will be understood that the spatial relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over, an element described as "beneath", "under" or "below" other elements or features will then be oriented "above" the other elements or features. Thus, the example terms "beneath" and "under" can include both an orientation of above and below. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatial relative descriptors used herein should be interpreted accordingly.

[0048] In addition, it will also be understood that when an element, component, region, layer, and / or portion is referred to as being "between" two elements, components, regions, layers, and / or portions, the element, component, region, layer, and / or portion can be the only element, component, region, layer, and / or portion between the two elements, components, regions, layers, and / or portions, or there can also be one or more intermediate elements, components, regions, layers, and / or portions.

[0049] As used herein, "substantially", "about", and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent deviations of measured or calculated values that would be recognized by a person of ordinary skill in the art.

[0050] As used herein, the term "use" and its variations can be considered to be synonymous with the term "utilize" and its variations, respectively.

[0051] In addition, any numerical range recited herein is intended to include all sub-ranges having the same numerical precision contained within the recited range. For example, a range of "1.0 to 10.0" or between "1.0 and 10.0" is intended to include all sub-ranges between the recited minimum value of 1.0 and the recited maximum value of 10.0 (and including that minimum and maximum value), i.e., having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations contained therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations contained therein. Accordingly, the applicant reserves the right to amend this specification (including the claims) to expressly recite any sub-ranges contained within the ranges expressly recited herein. All such ranges are intended to be inherently described in this specification such that amending to expressly recite any such sub-ranges will be in compliance.

[0052] According to an embodiment of the present invention, since resonance may be unsatisfactory and thus reduce the light efficiency when the reflectivity of the counter electrode is not high, a cover layer can be provided on the counter electrode to improve the light efficiency. The cover layer can have different refractive indices as a function of wavelength, and the value of color deviation (or variation) as a function of light efficiency and viewing angle can vary as a function of the refractive index of the cover layer.

[0053] For example, a flexible organic light-emitting display device can include a thin film encapsulation layer in contact with the cover layer, and considering the optical properties of the thin film encapsulation layer, the desired values of high light efficiency and color deviation can be achieved by determining the optical properties of the cover layer.

[0054] Reference will now be made to the embodiments, examples of which are illustrated in the accompanying drawings. Regardless of the figure numbers, those components that are the same or substantially the same may have the same reference numerals, and redundant descriptions may be omitted.

[0055] Figure 1 is a cross-sectional view of an organic light emitting display device according to an embodiment, Figure 2 is Figure 1 a cross-sectional view of a stacked structure of a first sub-pixel SP1, a second sub-pixel SP2, and a third sub-pixel SP3.

[0056] Referring to Figure 1 and Figure 2 , an organic light emitting display device according to an embodiment includes first to third sub-pixels SP1 to SP3 that emit (or are configured to emit) light of different colors, and includes: a substrate 110 including first to third regions 10 to 30 corresponding to the first to third sub-pixels SP1 to SP3, respectively; a first pixel electrode 141B, a second pixel electrode 141G, and a third pixel electrode 141R disposed on the first to third regions 10 to 30 of the substrate 110, respectively; a first organic emission layer 143B disposed on the first pixel electrode 141B and emitting light having a first wavelength; a second organic emission layer 143G disposed on the second pixel electrode 141G and emitting light having a second wavelength longer than the first wavelength; a third organic emission layer 143R disposed on the third pixel electrode 141R and emitting light having a third wavelength longer than the second wavelength; a counter electrode 145 covering the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R; a cover layer 150 disposed on the counter electrode 145; and a thin film encapsulation layer 160 disposed on the cover layer 150.

[0057] The pixel defining layer 125 may be disposed to partially overlap with each of the first pixel electrode 141B, the second pixel electrode 141G, and the third pixel electrode 141R to define the first to third sub-pixels SP1 to SP3. Based on the selective combination of light emitted from the first to third sub-pixels SP1 to SP3, the organic light emitting display device displays an image by using a plurality of pixels P that each emit a specific color of light.

[0058] According to an embodiment, the first sub-pixel SP1 to the third sub-pixel SP3 may emit blue light, green light, and red light, respectively. In other words, the first organic emission layer 143B may emit blue light including light of a first wavelength, the second organic emission layer 143G may emit green light including light of a second wavelength, and the third organic emission layer 143R may emit red light including light of a third wavelength. The first wavelength to the third wavelength may be 460 nm, 530 nm, and 620 nm, respectively. However, the embodiment is not limited thereto, and the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R may emit other suitable lights of different colors.

[0059] The organic light emitting display device may be a flexible organic light emitting display device, and the substrate 110 may be a flexible substrate that is easily bendable. Such a flexible substrate may include various suitable materials. For example, it may include polymer resins such as polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polyimide (PI), polycarbonate (PC), and / or cellulose acetate propionate (CAP). According to an embodiment, the substrate 110 may include PI having excellent bendable characteristics and may have a thickness of several micrometers to several tens of micrometers (μm).

[0060] The first pixel driver 130B, the second pixel driver 130G, and the third pixel driver 130R respectively electrically connected to the first pixel electrode 141B, the second pixel electrode 141G, and the third pixel electrode 141R are disposed on the substrate 110, and a buffer layer 121 may be disposed between the first pixel driver 130B, the second pixel driver 130G, and the third pixel driver 130R and the substrate 110. The buffer layer 121 may flatten the top surface of the substrate 110 and prevent or substantially prevent impurities from penetrating from the substrate 110 into the first pixel driver 130B, the second pixel driver 130G, and the third pixel driver 130R.

[0061] A planarization layer 123 covering the first pixel driver 130B, the second pixel driver 130G, and the third pixel driver 130R is disposed on the buffer layer 121 and may include a single layer or multiple layers of an inorganic material and / or an organic material. The first pixel driver 130B, the second pixel driver 130G, and the third pixel driver 130R may each include devices such as a plurality of thin film transistors and capacitors.

[0062] Refer to Figure 2, the first sub-pixel SP1 to the third sub-pixel SP3 respectively include a first organic light-emitting device (OLED) 140B, a second organic light-emitting device 140G, and a third organic light-emitting device 140R. The counter electrode 145, the cover layer 150, and the thin film encapsulation layer 160 can be continuously disposed in the first region 10 to the third region 30 of the entire substrate 110 to cover the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R.

[0063] The first OLED 140B, the second OLED 140G, and the third OLED 140R can form a microcavity, and the first pixel electrode 141B, the second pixel electrode 141G, and the third pixel electrode 141R can be reflective electrodes. In other words, the organic light-emitting display device can be a top-emission type display device, in which light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R is emitted outward through the counter electrode 145.

[0064] The first pixel electrode 141B, the second pixel electrode 141G, and the third pixel electrode 141R can each include a reflective layer 141a and transparent conductive layers 141b and 141c respectively disposed under and on the reflective layer 141a. The transparent conductive layers 141b and 141c can each include at least one selected from indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), indium gallium oxide (IGO), and aluminum zinc oxide (AZO), and the reflective layer 141a can include at least one selected from silver (Ag), Al, magnesium (Mg), lithium (Li), calcium (Ca), copper (Cu), lithium fluoride (LiF) / Ca, LiF / Al, Mg / Ag, and CaAg. For example, the first pixel electrode 141B, the second pixel electrode 141G, and the third pixel electrode 141R can be a three-layer of ITO / Ag / ITO.

[0065] The counter electrode 145 can include at least one of Li, Ca, LiF / Ca, LiF / Al, Al, Ag, Mg, and gold (Au), and can be a single layer or a multi-layer. The counter electrode 145 can be formed of a metal having a very small thickness of several nanometers to several tens of nanometers, can have a refractive index less than 1, and can have a very high extinction coefficient k.

[0066] The cover layer 150 can be disposed on the counter electrode 145 and can have a refractive index of 1.9 to 2.3 at a wavelength of about 530 nm.

[0067] When the cover layer 150 is not provided on the counter electrode 145, the reflectivity of the light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R at the counter electrode 145 is very low. Therefore, the resonance efficiency of the microcavity formed by the first pixel electrode 141B, the second pixel electrode 141G, the third pixel electrode 141R, and the counter electrode 145 is low, and as a result, the light extraction efficiency of the organic light-emitting display device is low.

[0068] In the present disclosure, the cover layer 150 having a relatively high refractive index is provided on the counter electrode 145. Due to the cover layer 150, the reflectivity of the light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R at the counter electrode 145 is high. Therefore, the resonance efficiency of the microcavity is high, and thus the light extraction efficiency of the organic light-emitting display device is high.

[0069] Here, the reflection at the counter electrode 145 may include not only the reflection at the bottom surface of the counter electrode 145, but also the reflection at the interface between the counter electrode 145 and the cover layer 150 and the reflection at the interface between the cover layer 150 and the thin film encapsulation layer 160. In other words, the ratio of the light reflected at the counter electrode 145 and returned to the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R to the light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R and incident on the counter electrode 145 may be defined as the reflectivity at the counter electrode 145, and the "resonance efficiency" may also be defined by a concept that is the same as or substantially the same as the reflectivity at the counter electrode 145.

[0070] The reflectivity (i.e., resonance efficiency) at the counter electrode 145 may vary according to the refractive index of the cover layer 150. In other words, the light extraction efficiencies of the first sub-pixel SP1 to the third sub-pixel SP3 may all vary according to the refractive index of the cover layer 150 with respect to the wavelength of the emitted light.

[0071] The first lower functional layer 142B may be provided between the first pixel electrode 141B and the first organic emission layer 143B, the second lower functional layer 142G may be provided between the second pixel electrode 141G and the second organic emission layer 143G, and the third lower functional layer 142R may be provided between the third pixel electrode 141R and the third organic emission layer 143R. The first lower functional layer 142B, the second lower functional layer 142G, and the third lower functional layer 142R may all be a hole injection layer, a hole transport layer, and / or another functional layer.

[0072] According to an embodiment, the thicknesses t1 to t3 of the first lower functional layer 142B, the second lower functional layer 142G, and the third lower functional layer 142R may be different from each other. In order to improve the light extraction efficiency of the first sub-pixel SP1 to the third sub-pixel SP3, the distances between the first pixel electrode 141B, the second pixel electrode 141G, and the third pixel electrode 141R and the counter electrode 145 may be set to satisfy the constructive interference condition. In other words, since the wavelengths of the light emitted from the first OLED 140B, the second OLED 140G, and the third OLED 140R are different from each other, the resonance distances between the first pixel electrode 141B and the counter electrode 145, between the second pixel electrode 141G and the counter electrode 145, and between the third pixel electrode 141R and the counter electrode 145 are different from each other, and the first lower functional layer 142B, the second lower functional layer 142G, and the third lower functional layer 142R may serve as resonance distance adjustment layers for adjusting such resonance distances.

[0073] The first upper functional layer 144B, the second upper functional layer 144G, and the third upper functional layer 144R may be respectively disposed between the first organic emission layer 143B and the counter electrode 145, between the second organic emission layer 143G and the counter electrode 145, and between the third organic emission layer 143R and the counter electrode 145. The first upper functional layer 144B, the second upper functional layer 144G, and the third upper functional layer 144R may be an electron injection layer, an electron transport layer, and / or another functional layer.

[0074] In Figure 2 , the first lower functional layer 142B, the second lower functional layer 142G, and the third lower functional layer 142R serve as resonance distance adjustment layers, and the first upper functional layer 144B, the second upper functional layer 144G, and the third upper functional layer 144R have the same or substantially the same thickness, but the embodiment is not limited thereto. In other words, the first upper functional layer 144B, the second upper functional layer 144G, and the third upper functional layer 144R may serve as resonance distance adjustment layers, or all of the first lower functional layer 142B, the second lower functional layer 142G, the third lower functional layer 142R, the first upper functional layer 144B, the second upper functional layer 144G, and the third upper functional layer 144R may serve as resonance distance adjustment layers. In addition, at least some of the first lower functional layer 142B, the second lower functional layer 142G, the third lower functional layer 142R, the first upper functional layer 144B, the second upper functional layer 144G, and the third upper functional layer 144R may be continuously formed in the entire first sub-pixel SP1 to the third sub-pixel SP3, or may be respectively disposed in the first sub-pixel SP1 to the third sub-pixel SP3.

[0075] An overcoat layer 150 having a substantially uniform thickness t0 among the entire first sub-pixel SP1 to third sub-pixel SP3 may be disposed on the counter electrode 145. According to an embodiment, the thickness t0 of the overcoat layer 150 may be from to For example, the thickness t0 of the overcoat layer 150 may be from to

[0076] The overcoat layer 150 may have a refractive index of 1.9 to 2.3 at 530 nm (second wavelength), the refractive index at 460 nm (first wavelength) may be at least 7% higher than the refractive index at 530 nm (second wavelength), and the refractive index at 620 nm (third wavelength) may be at least 3% smaller than the refractive index at 530 nm (second wavelength). For example, the refractive index of the overcoat layer 150 at 460 nm may be 8% to 15% higher than the refractive index at 530 nm.

[0077] According to an embodiment, the overcoat layer 150 may include a triamine derivative, a carbazole biphenyl derivative, an arylenediamine derivative, or tris(8-hydroxyquinoline) aluminum (Alq3), and by adjusting the composition of such derivatives, a material having a refractive index according to wavelength as described above can be achieved.

[0078] A thin film encapsulation layer 160 in contact with the overcoat layer 150 is disposed above the overcoat layer 150. The thin film encapsulation layer 160 may include a first encapsulation inorganic film 160I1 provided as the lowermost layer, an encapsulation organic film 165, and a second encapsulation inorganic film 167. According to an embodiment, the first encapsulation inorganic film 160I1 may include a first lower encapsulation inorganic film 161 and a first upper encapsulation inorganic film 163, wherein the first lower encapsulation inorganic film 161 may include LiF.

[0079] The refractive index n1 of the first lower encapsulation inorganic film 161 may be 1.35 to 1.45. In other words, the refractive index of the first lower encapsulation inorganic film 161 may be less than the refractive index of the overcoat layer 150 and higher than 1 (i.e., the refractive index of air).

[0080] According to an embodiment, the first upper encapsulation inorganic film 163 and the second encapsulation inorganic film 167 may both include any one selected from aluminum oxide (Al2O3), silicon oxide (SiO2), silicon nitride (SiN x ) and silicon oxynitride (SiO x N y ), and the encapsulation organic film 165 may include an acrylic material.

[0081] For example, the refractive index n2 of the first upper encapsulation inorganic film 163, the refractive index n3 of the encapsulation organic film 165, and the refractive index n4 of the second upper encapsulation inorganic film 167 can be 1.7 to 1.85, 1.45 to 1.55, and 1.7 to 1.85, respectively. Such refractive indices are at a wavelength of 530 nm.

[0082] Therefore, the refractive index n of the counter electrode 145 e , the refractive index n of the cover layer 150 c , the refractive index n1 of the first lower encapsulation inorganic film 161, the refractive index n2 of the first upper encapsulation inorganic film 163, and the refractive index n3 of the encapsulation organic film 165 can satisfy the following conditional expression, where the refractive index n4 of the second upper encapsulation inorganic film 167 and the refractive index n2 of the first upper encapsulation inorganic film 163 can be substantially the same.

[0083] <Conditional expression>

[0084] n c > n2 > n3 > n1 > n e

[0085] The organic light emitting display device can be a flexible organic light emitting display device that can be bent, and can use the thin film encapsulation layer 160 with high flexibility to protect the first OLED 140B, the second OLED 140G, and the third OLED 140R that are easily denatured by moisture or oxygen.

[0086] Therefore, the cover layer 150 and the thin film encapsulation layer 160 are in contact with each other, and the light efficiency and viewing angle characteristics of the organic light emitting display device can be changed according to the refractive indices of the cover layer 150 and the layers included in the thin film encapsulation layer 160.

[0087] According to an embodiment, the cover layer 150 having a uniform thickness throughout the first sub-pixel SP1 to the third sub-pixel SP3 has a refractive index at 460 nm (first wavelength) that is at least 7% higher than the refractive index at 530 nm (second wavelength), and a refractive index at 620 nm (third wavelength) that is at least 3% smaller than the refractive index at 530 nm (second wavelength). According to such a configuration, the resonance efficiency of the first sub-pixel SP1 that emits blue light is higher than the resonance efficiency of the second sub-pixel SP2 that emits green light, and the resonance efficiency of the third sub-pixel SP3 that emits red light is smaller than the resonance efficiency of the second sub-pixel SP2. When the difference in the refractive index of the cover layer 150 increases, this difference in resonance efficiency can increase. However, the thin film encapsulation layer 160 in contact with the cover layer 150 reduces the difference in resonance efficiency, and in this regard, in order to increase the difference in resonance efficiency between the first sub-pixel SP1 to the third sub-pixel SP3, the refractive index of the cover layer 150 at 460 nm can be at least 7% higher than the refractive index at 530 nm, and the refractive index at 620 nm can be at least 3% smaller than the refractive index at 530 nm.

[0088] Based on this difference in resonance efficiency, color deviation in the side view with respect to the color in the front view of the organic light-emitting display device is achieved, such that blue is further enhanced. In an organic light-emitting display device, color deviation in the side view inevitably occurs. When color deviation is achieved such that blue is enhanced, it is difficult for a user (i.e., a viewer) to recognize the color deviation, but when color deviation is achieved such that green or red is enhanced, it is easy for the user to recognize the color deviation.

[0089] By setting the refractive index of the cover layer 150 that directly affects the resonance efficiency such that the resonance efficiency of the first sub-pixel SP1 that emits blue light is higher than the resonance efficiency of the second sub-pixel SP2 and the third sub-pixel SP3, not only can the light efficiency be improved, but also color deviation in the side view can be achieved such that blue is enhanced.

[0090] Figure 3A is a diagram of the light extraction efficiency in the first sub-pixel SP1 to the third sub-pixel SP3 when the refractive index of the cover layer 150 is the same at the first wavelength to the third wavelength, Figure 3B is a diagram of the light extraction efficiency in the first sub-pixel SP1 to the third sub-pixel SP3 when the condition that the refractive index at the first wavelength > the refractive index at the second wavelength > the refractive index at the third wavelength is satisfied.

[0091] Figure 3A and 3B both show such a situation: for example, adjusting the resonance distance such that the light extraction efficiency of the first sub-pixel SP1 that emits blue light is higher than the light extraction efficiency of the second sub-pixel SP2 that emits green light and the third sub-pixel SP3 that emits red light. Specifically, Figure 3A shows whenFigure 1 The refractive index n of the cover layer 150 at the first wavelength (460 nm) c1 and the refractive index n at the second wavelength (530 nm) c2 and the refractive index n at the third wavelength (620 nm) c3 The relative values of the light extraction efficiency of the first sub-pixel SP1 to the third sub-pixel SP3 when they are the same Figure 3B show that when n c1 : n c2 : n c3 is 1.2:1.1:1, the relative values of the light extraction efficiency of the first sub-pixel SP1 to the third sub-pixel SP3

[0092] It is determined by the graphs of Figure 3A and Figure 3B that when the difference in the refractive index of the cover layer 150 increases, the difference in the light extraction efficiency between the first sub-pixel SP1 to the third sub-pixel SP3 increases

[0093] According to the embodiment, by increasing the refractive index of the cover layer 150 at 460 nm, the light extraction efficiency of the first sub-pixel SP1 that emits blue light including 460 nm can be further increased

[0094] Figure 4 is a graph of the refractive index of the cover layer 150 as a function of wavelength included in the embodiment Figure 5 is the cover layer of the comparative example and Figure 4 a table of the refractive indices of the cover layer 150 at 460 nm, 530 nm, and 620 nm Figure 6A and Figure 6B are graphs of color deviation as a function of viewing angle in the ultraviolet (UV) coordinate system in the comparative example and Figure 5 the example (CPLf), respectively

[0095] Referring to Figure 4 and Figure 5 in the embodiment, the refractive index of the cover layer 150 included gradually decreases in the entire range of 460 nm to 620 nm, and specifically, has a very large gradient in the range of 460 nm to 530 nm

[0096] Figure 5 The values in the top three rows of the table of

[0097] In the comparative example, the refractive index of the cover layer at 460 nm is 4.5% higher than that at 530 nm, and the refractive index at 620 nm is 2.5% lower than that at 530 nm. However, in the embodiment, the refractive index of the cover layer 150 at 460 nm is at least 7% higher than that at 530 nm, and the refractive index at 620 nm is at least 3% lower than that at 530 nm. For example, the refractive index of the cover layer 150 at 460 nm can be at least 8% higher than that at 530 nm.

[0098] Figure 6A and Figure 6B respectively show Figure 4 and Figure 5 the viewing angle characteristics in the comparative example and the example (CPLf), where Figure 6A and Figure 6B the diagrams of show the distribution of color deviation in the UV coordinate system, and it is determined that in the distribution of color deviation in both Figure 6A and Figure 6B the Δuv is within the range of 0.015.

[0099] However, in the Figure 6A comparative example, the color deviation has no directionality in the direction where the user cannot recognize the color deviation (the direction indicated by arrow A), but the color deviation occurs in the direction perpendicular to arrow A. In this case, the viewing angle increases in the side direction relative to the front, so the color deviation occurs in the green or red direction rather than the blue direction, and thus it can be easily recognized by the user. Specifically, the value of the color deviation is outside arrow A at the 45° side viewing angle.

[0100] In the Figure 6B example (CPLf), the color deviation has directionality in the direction where the user cannot recognize the color deviation (the direction indicated by arrow A). In this case, the viewing angle increases in the side direction relative to the front, so the color deviation occurs in the blue direction, and thus it may not be easily recognized by the user. Specifically, the value of the color deviation is on arrow A at the 45° side viewing angle.

[0101] As shown in Figure 6A and Figure 6B , the desired value of the color deviation can be achieved by adjusting the refractive index of the cover layer 150 as a function of the wavelength.

[0102] Figures 7A to 7D is a graph of the resonance efficiency and light absorption rate as a function of the wavelength according to Example 1 to Example 3 and the comparative example.

[0103] Here, the resonance efficiency corresponds to the degree of light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R (the light is reflected back to the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R from the bottom surface of the counter electrode 145, the interface between the counter electrode 145 and the cover layer 150, and the interface between the cover layer 150 and the thin film encapsulation layer 160), and represents the ratio of the reflected light to the light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R and incident on the counter electrode 145.

[0104] In addition, the light absorption rate represents the degree to which the light emitted from the first organic emission layer 143B, the second organic emission layer 143G, and the third organic emission layer 143R and incident on the counter electrode 145 is absorbed by the counter electrode 145 and the like.

[0105] Figure 7A Shows when according to Example 1 Figure 1 the refractive index of the cover layer 150 is 2.25, 2.01, and 1.9 at 460 nm, 530 nm, and 620 nm respectively and when the thickness t0 of the cover layer 150 is and the resonance efficiency and the light absorption rate.

[0106] In other words, the refractive index of the cover layer 150 at 460 nm is 11.9% higher than the refractive index at 530 nm, and the refractive index at 620 nm is 5.5% smaller than the refractive index at 530 nm. Referring to Figure 7A the graph, at a thickness of the resonance efficiency at 460 nm is approximately 85% higher than the resonance efficiency at 530 nm, at a thickness of it is approximately 60% higher, and at a thickness of it is approximately 30% higher.

[0107] Figure 7B Shows when according to Example 2 Figure 1 the refractive index of the cover layer 150 is 2.44, 2.15, and 2.03 at 460 nm, 530 nm, and 620 nm respectively and when the thickness t0 of the cover layer 150 is and the resonance efficiency and the light absorption rate.

[0108] In other words, the refractive index of the cover layer 150 at 460 nm is 13.5% higher than the refractive index at 530 nm, and the refractive index at 620 nm is 5.6% smaller than the refractive index at 530 nm. Referring to Figure 7B the graph, at a thickness of The resonance efficiency at 460 nm is approximately 95% higher than that at 530 nm, approximately 50% higher at a thickness of and approximately 15% higher at a thickness of .

[0109] Figure 7C shows the resonance efficiency and light absorption rate when the refractive index of the cover layer 150 according to Example 3 is 2.25, 2.01, and 1.9 at 460 nm, 530 nm, and 620 nm, respectively, and when the thickness t0 of the cover layer 150 is and .

[0110] Figure 7C In other words, the refractive index of the cover layer 150 at 460 nm is 11.9% higher than that at 530 nm, and the refractive index at 620 nm is 5.5% smaller than that at 530 nm. Referring to the graph, the resonance efficiency at 460 nm is approximately 100% higher than that at 530 nm at a thickness of , approximately 75% higher at a thickness of , and approximately 14% higher at a thickness of .

[0111] Figure 7D shows the resonance efficiency and light absorption rate when the refractive index of the cover layer according to the comparative example is 2.02, 1.96, and 1.93 at 460 nm, 530 nm, and 620 nm, respectively, and when the thickness of the cover layer is and .

[0112] Figure 7D In other words, the refractive index of the cover layer at 460 nm is 3.1% higher than that at 530 nm, and the refractive index at 620 nm is 1.5% smaller than that at 530 nm. Referring to the graph, the resonance efficiency at 460 nm is approximately 30% higher than that at 530 nm at a thickness of , approximately 40% higher at a thickness of , and approximately 30% higher at a thickness of .

[0113] In other words, in the comparative example, the resonance efficiency at 460 nm is not at least 50% higher than that at 530 nm. Therefore, the light extraction efficiency of the first sub-pixel SP1 emitting blue light is not sufficiently higher than that of the second sub-pixel SP2 emitting green light.

[0114] However, in Examples 1 to 3, at a thickness of​ and The resonance efficiency at 460 nm is at least 50% and at least 100% higher than the resonance efficiency at 530 nm. In other words, when the refractive index of the cover layer 150 is equal to or greater than a specific value according to the wavelength difference, the light extraction efficiency of the first sub-pixel SP1 that emits blue light can be sufficiently high, and thus, the color deviation according to the viewing angle can be directional.

[0115] Figure 8 is a cross-sectional view of the cover layer 250 and the thin film encapsulation layer 260 according to another embodiment.

[0116] Referring to Figure 8 , the organic light emitting display device according to the embodiment includes a cover layer 250 disposed on the counter electrode 245 and a thin film encapsulation layer 260 disposed on the cover layer 250. The structure between the substrate (e.g., Figure 1 substrate 110) and the counter electrode 245 can be the same as or similar to that of Figure 1 the organic light emitting display device.

[0117] The thin film encapsulation layer 260 includes a first encapsulation inorganic film 261 and a second encapsulation inorganic film 267, and an encapsulation organic film 265 can be disposed between the first encapsulation inorganic film 261 and the second encapsulation inorganic film 267. Alternatively, an inorganic material (such as hexamethyldisiloxane (HMDSO)) that can absorb the stress of the inorganic film like an organic film can be disposed between the first encapsulation inorganic film 261 and the second encapsulation inorganic film 267 instead of the encapsulation organic film 265.

[0118] The first encapsulation inorganic film 261 and the second encapsulation inorganic film 267 can both include at least one of Al2O3, SiO2, SiN x and SiO x N y and can both have a refractive index of 1.7 to 1.85.

[0119] The cover layer 250 contacts the first encapsulation inorganic film 261, and the refractive index of the cover layer 250 can be higher than the refractive index of the first encapsulation inorganic film 261.

[0120] Figure 9 is a cross-sectional view of the cover layer 350 and the thin film encapsulation layer 360 according to another embodiment.

[0121] Referring to Figure 9 , the organic light emitting display device according to the embodiment includes a cover layer 350 disposed on the counter electrode 345 and a thin film encapsulation layer 360 disposed on the cover layer 350. The structure between the substrate (e.g., Figure 1 substrate 110) and the counter electrode 345 can be the same as that of Figure 1is the same as, substantially the same as, or similar to the organic light emitting display device.

[0122] The thin film encapsulation layer 360 includes a first encapsulation inorganic film 360 I1 , an encapsulation organic film 365, and a second encapsulation inorganic film 360 I2 , wherein the first encapsulation inorganic film 360 I1 may include a first lower encapsulation inorganic film 361 and a first upper encapsulation inorganic film 363, and the second encapsulation inorganic film 360 I2 may include a second lower encapsulation inorganic film 367 and a second upper encapsulation inorganic film 369.

[0123] The first lower encapsulation inorganic film 361 may include LiF and may have a refractive index of 1.35 to 1.45. The first upper encapsulation inorganic film 363 may include any one of Al2O3, SiO2, SiN x and SiO x N y and may have a refractive index of 1.7 to 1.85.

[0124] Both the second lower encapsulation inorganic film 367 and the second upper encapsulation inorganic film 369 may include SiN x , but may have different refractive indices by being formed under different process conditions.

[0125] As Figure 1 , Figure 8 and Figure 9 shown in, the thin film encapsulation layers 160, 260, and 360 may have various suitable structures, but in all cases, the lowermost layers of the thin film encapsulation layers 160, 260, and 360 are in contact with the cover layers 150, 250, and 350, respectively. In addition, the refractive indices of all suitable layers included in the thin film encapsulation layers 160, 260, and 360 may be lower than the refractive indices of the cover layers 150, 250, and 350, respectively, and may all have a structure in which high refractive index layers and low refractive index layers are stacked on each other.

[0126] Thus, in an organic light emitting display device including a cover layer 150, 250, or 350 and a thin film encapsulation layer 160, 260, or 360 in contact with the cover layer 150, 250, or 350, the light extraction efficiency of the first sub-pixel SP1 that emits blue light is particularly increased, and thus, a desired directivity can be assigned to the color deviation according to the viewing angle.

[0127] The directivity of this color deviation may be such that color deviation occurs but the user cannot recognize the direction of the color deviation. Thus, the organic light emitting display device can display high-quality images.

[0128] The organic light-emitting display device according to the above-described embodiment includes a cover layer disposed on the counter electrode of the OLED, and the cover layer has a specific refractive index according to wavelength, so that the light efficiency is increased and color deviation according to the viewing angle is achieved in a direction in which color deviation is not easily recognized by the user.

[0129] It should be understood that the embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. The description of features or aspects within each embodiment should generally be considered applicable to other similar features or aspects in other embodiments.

[0130] Although the present invention has been described with respect to certain specific embodiments, those skilled in the art will have no difficulty in devising variations of the described embodiments, which in no way depart from the scope and spirit of the present invention. Moreover, for those skilled in the art in various fields, the invention described herein will itself suggest solutions for other tasks and adaptation modifications for other applications. The applicant's intention is to cover all such uses of the invention and those changes and modifications that can be made to the embodiments of the invention selected herein for the purpose of disclosure without departing from the spirit and scope of the invention. Therefore, the given embodiments of the invention should be considered illustrative rather than restrictive in all respects, and the scope of the invention is indicated by the appended claims and their equivalents.

Claims

1. An organic light emitting display device, the organic light emitting display device including a first sub-pixel, a second sub-pixel, and a third sub-pixel configured to emit lights of different colors, the organic light emitting display device comprising: A first pixel electrode, a second pixel electrode, and a third pixel electrode, respectively in the first sub-pixel to the third sub-pixel; A first organic emission layer, located on the first pixel electrode, and configured to emit blue light including a first wavelength; A second organic emission layer, located on the second pixel electrode, and configured to emit green light including a second wavelength, the second wavelength being longer than the first wavelength; A third organic emission layer, located on the third pixel electrode, and configured to emit red light including a third wavelength, the third wavelength being longer than the second wavelength; A counter electrode, continuously disposed on the first organic emission layer to the third organic emission layer; And A cover layer, located on the counter electrode, continuously located throughout the first sub-pixel to the third sub-pixel with a uniform thickness, and having a refractive index with respect to the first wavelength that is at least 7% higher than the refractive index with respect to the second wavelength.

2. The organic light emitting display device according to claim 1, the organic light emitting display device further comprising: A thin film encapsulation layer, located on the cover layer to contact the cover layer.

3. The organic light emitting display device according to claim 2, wherein The thin film encapsulation layer includes a first lower encapsulation inorganic film, a first upper encapsulation inorganic film, an encapsulation organic film, and a second encapsulation inorganic film sequentially disposed.

4. The organic light emitting display device according to claim 3, wherein, The refractive indices of the first lower encapsulation inorganic film, the first upper encapsulation inorganic film, the encapsulation organic film, and the second encapsulation inorganic film are 1.35 to 1.45, 1.7 to 1.85, 1.45 to 1.55, and 1.7 to 1.85, respectively.

5. The organic light-emitting display device according to claim 1, wherein, The refractive index of the cover layer with respect to the third wavelength is at least 3% smaller than the refractive index with respect to the second wavelength.

6. The organic light emitting display device according to claim 1, wherein The cover layer has a refractive index of 1.9 to 2.3 with respect to the second wavelength.

7. The organic light emitting display device according to claim 1, wherein The thickness of the covering layer is to

Images