Light emitting display device

Abstract

Disclosed is a light emitting display device that emits constant light by maintaining a cavity of internal light by a reverse cavity characteristic through an optical compensation structure, and that, by combining the optical compensation structure with a color filter structure, achieves a high luminance characteristic despite a change in viewing angle, prevents external light from being reflected, and is excellent in efficiency and lifespan.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a display device, and more particularly, to a light emitting display device for preventing a viewing angle from changing according to luminance and maintaining high luminance regardless of a viewing angle by changing a configuration. BACKGROUND

[0002] Self-luminous display devices such as organic light emitting displays or quantum dot light emitting displays, which perform compact and clear color display without a separate light source, have been considered as a competitive application.

[0003] A self-luminous display device includes a plurality of pixels on a substrate, a first electrode and a second electrode facing each other in each pixel, and a light emitting diode including a light emitting layer between the first electrode and the second electrode. SUMMARY

[0004] The light emitting display device is designed using a principle in which light resonates between two opposite electrodes and is optimized for a front light emitting type device, and thus, there is a problem in that luminance is reduced when a viewing angle of the display changes. Accordingly, the inventors have recognized the above problem and have proposed the present invention.

[0005] The present disclosure relates to a light emitting display device for allowing a user to view an image having high luminance in any direction by changing an internal structure of the light emitting display device to reduce a dependence of a wavelength on a viewing angle of emitted light.

[0006] Additional features and aspects will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the inventive concepts provided herein. The novel concepts can be realized and obtained by means of the structures particularly pointed out in the description and claims hereof as well as in the appended drawings.

[0007] The light emitting display device according to the present disclosure can emit constant light by using a cavity that maintains internal light by using a reverse cavity characteristic through an optical compensation structure, and by combining the optical compensation structure with a color filter structure, a high luminance characteristic can be achieved despite a viewing angle change, external light can be prevented from being reflected, and can be excellent in efficiency and lifespan.

[0008] In one aspect, the present disclosure provides a display device including a substrate including a plurality of light emitting cells, a light emitting layer at the light emitting cells, a reflective structure between the light emitting layer and the substrate in the light emitting cells, a transmissive electrode over the light emitting layer across the plurality of pixels on the substrate, an optical compensation structure in contact with the transmissive electrode and having a destructive interference characteristic, an encapsulation layer on the optical compensation structure, and a color filter on the encapsulation layer.

[0009] The display device can include a first layer of a first refractive index and a second layer of a second refractive index greater than the first refractive index, and a thickness of the first layer can be 1.8 to 2.2 times greater than a thickness of the second layer.

[0010] In another aspect, the disclosure provides a display device including a light emitting device including a light emitting layer on a substrate, an optical compensation structure disposed on the light emitting device including a first layer of a first refractive index and a second layer of a second refractive index, the first layer being thicker than the second layer, an encapsulation layer on the optical compensation structure, and a color filter on the encapsulation layer.

[0011] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the subject application concept. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and serve to explain the principles of the disclosure. In the drawings:

[0013] Figure 1 is a cross-sectional view of a light emitting display device according to a first embodiment of the disclosure;

[0014] Figures 2A-2C is a cross-sectional view of an example of an optical compensation structure according to various embodiments of the disclosure.

[0015] Figure 3 is a cross-sectional view of a light emitting display device according to a second embodiment of the disclosure;

[0016] Figure 4 is a cross-sectional view of a dielectric Bragg mirror of Figure 3

[0017] Figure 5A and Figure 5B is a graph showing the principle of a mirror of a dielectric Bragg mirror and its reflectivity;

[0018] Figure 6 is a cross-sectional view of a light emitting display device of a third embodiment of the disclosure;

[0019] Figures 7A-7C is a graph showing luminance characteristics with respect to each viewing angle of red, green, and blue in first to fourth experimental examples;

[0020] Figures 8A-8C is a graph showing color luminance deviation with respect to each viewing angle of red, green, and blue according to first to fourth experimental examples;​

[0021] Figures 9A-9C is a graph showing color coordinate fluctuations according to changes in viewing angle with respect to red, green, and blue according to the first to third experimental examples;

[0022] Figure 10 is a graph showing a change in transmittance for each wavelength of a structure applying a color filter according to a third experimental example;

[0023] Figure 11A and Figure 11B is a graph showing EL spectra according to the second experimental example and the third experimental example;

[0024] Figure 12 is a diagram illustrating a light-emitting display device according to one or more embodiments of the present disclosure;

[0025] Figure 13 is a cross-sectional view showing a display device according to a fourth embodiment of the present disclosure; and

[0026] Figure 14 yes Figure 13 A plan view of a display device.

[0027] Throughout the drawings and detailed description, unless otherwise described, the same drawing reference numerals should be understood to refer to the same elements, features, and structures. The relative size and depiction of these elements may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0028] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are shown in the accompanying drawings. In the following description of the embodiments and the accompanying drawings, identical or similar elements are represented by the same reference numerals throughout the specification. In the following description of the embodiments of the present invention, when a detailed description of known functions and configurations incorporated herein may make the subject matter of the present invention unclear, its detailed description will be omitted. In addition, the names of the elements used in the following description of the embodiments of the present invention are selected in consideration of ease of preparation of the specification, and therefore can be distinguished from the names of the components of the actual product.

[0029] The shapes, sizes, ratios, angles and quantities of the elements of the description embodiments of the present invention given in the drawings are merely exemplary, and therefore, the present invention is not limited to the details shown. In the following description of the embodiments, the terms "comprise", "include" and "have" will be interpreted as indicating the presence of one or more other characteristics, numbers, steps, operations, elements or parts described in the specification, or a combination thereof, and unless the term "only" is used, the existence of other characteristics, numbers, steps, operations, elements, parts or a combination thereof or the possibility of adding other characteristics, numbers, steps, operations, elements, parts or a combination thereof are not excluded. It will be understood that, unless otherwise stated, the singular expression of (one or more) elements includes plural expression.

[0030] When explaining the elements included in the various embodiments of the present invention, it should be understood that the elements include a range of error unless otherwise specified.

[0031] In the following description of the embodiments, it will be understood that when a positional relationship is expressed, for example, when an element is referred to as being "on," "above," "below," or "beside" another element, unless the term "only" or "directly" is used, the two elements may be in direct contact with each other, or one or more other elements may be inserted between the two elements.

[0032] In the following description of the embodiments, it will be understood that when temporal relationships are used, for example, when terms expressing a sequence of events are used (such as "after", "subsequently", "next" and "before"), unless the terms "only" or "directly" are used, the terms cover both continuous relationships between events and discontinuous relationships between events.

[0033] In the following description of the embodiments, it will be understood that when the terms "first," "second," etc. are used to describe various elements, these terms are only used to distinguish between identical or similar elements. Therefore, without departing from the technical scope of the present invention, the first element described below may be referred to as the second element.

[0034] The corresponding features of various embodiments of the present invention may be partially or completely coupled or combined with each other and interlocked or driven in various technical ways, and the corresponding embodiments may be implemented independently of each other or implemented together through the connection therebetween.

[0035] Hereinafter, the present disclosure will be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown.

[0036] Figure 1 is a cross-sectional view of a light emitting display device according to a first embodiment of the present disclosure. All components of the display device according to all embodiments of the present invention are operatively coupled and configured.

[0037] In Figure 1 In the light emitting display device according to the first embodiment of the disclosure, the light emitting display device can include: a substrate 100 having a plurality of light emitting cells; light emitting layers R-EML, G-EML, and B-EML included in the light emitting cells; a reflective structure (or a reflective layer) 111 disposed between the light emitting layers R-EML, G-EML, and B-EML in the light emitting cells and the substrate 100; a transmissive electrode (e.g., a cathode, a second electrode) 170 located above the light emitting layers over a plurality of pixels on the substrate; an optical compensation structure 180 in contact with the transmissive electrode (second electrode) 170 and having a destructive interference characteristic; an encapsulation layer 190 located on the optical compensation structure 180; and color filters 210a, 210b, and 210c located on the encapsulation layer 190.

[0038] The light emitting display device according to the first embodiment of the disclosure can use the reflective structure 111 formed of a reflective metal as a first electrode of a light emitting device.

[0039] The first electrode of the light emitting device according to the embodiments of the disclosure can function as an anode, and the second electrode 170 can function as a cathode.

[0040] The device including the reflective structure 111 including the first electrode, the second electrode 170, and layers 141, 142, and 160, such as R-EML / G-EML / B-EML, between them, the light emitting layers, the electrode injection layer (EIL) 160, is referred to as a light emitting device.

[0041] Here, when the reflective structure 111 is formed of a reflective metal, if the reflective structure 111 has a thickness equal to or greater than 100 nm, uniform reflectance with respect to all wavelengths can be achieved.

[0042] The optical compensation structure 180 can have a destructive interference characteristic, thereby reducing the amount of light returned inside the light emitting device by reducing the reflection of a large portion of light generated by the light emitting device and transmitted through the second electrode 170 at the interface between the second electrode 170 and the optical compensation structure 180, and the light transmitted from the lower portion of the light emitting device is transmitted outside the optical compensation structure 180. For example, the light has low reflectance at the second electrode 170 and the optical compensation structure 180, and a large portion of the light is transmitted through the second electrode 170 and the optical compensation structure 180.

[0043] The principle of light transmission from the second electrode 170 of the light emitting device through the optical compensation structure 180 according to the embodiments of the disclosure will be described. When the optical compensation structure 180 includes a plurality of insulating layers, the optical distance between the insulating layers generally has a condition represented by the following Expression 1.

[0044] [Expression 1]

[0045] For dielectric δ=π, m=0,2,4…

[0046] However, in the display device according to an embodiment of the present disclosure, light is transmitted through the second electrode 170 of the electrode assembly and the optical compensation structure 180 of the insulating layer, and thus the optical distance between the insulating layers can be calculated based on the principle expressed by the following Expression 2, further considering reflection at the metal.

[0047] [Expression 2]

[0048] For metals m=0,2,4...

[0049] Here, δ may be a phase at the interface, may be 0 or π in the case of an insulating layer, and may be 0 or π in the case of a metal interface.

[0050] In this case, when considering the above expression 2 to maintain the destructive interference characteristics of the optical compensation structure 180 according to an embodiment of the present disclosure, and the wavelength of light emitted from the light-emitting device is λ, the thickness of the optical compensation structure 180 and the refractive index of the material of the insulating layer included therein can be considered to satisfy the conditions of the above expression. When a plurality of insulating layers having different refractive indices are present in the optical compensation structure 180, the effective refractive index can be calculated taking into account the volume ratio of the insulating layers.

[0051] For example, when the optical compensation structure 180 includes a first layer 181 (e.g., OPL1) and a second layer 182 (e.g., OPL2) for destructive interference, the thickness of the layer with the low refractive index can be at least 1.8 times to 2.2 times greater than the thickness of the layer with the high refractive index.

[0052] The display device according to an embodiment of the present disclosure may include color filters 210a, 210b, and 210c on the encapsulation layer 190 for protecting the light emitting device, and the color filters 210a, 210b, and 210c may shield external light even without a separate polarizer, thereby improving optical efficiency.

[0053] Therefore, the display device according to the embodiment of the present disclosure may include a reflective structure 111, an optical compensation structure 180 having destructive interference characteristics and arranged above the light-emitting device, and color filters 210a, 210b and 210c, thereby improving the efficiency of light emitted inside the display device and preventing external light from being reflected.

[0054] For example, the encapsulation layer 190 may be formed by alternately stacking an inorganic encapsulation layer and an organic encapsulation layer, or may be configured by disposing an inorganic protective layer on the optical compensation structure 180 and applying a counter substrate and a face seal thereto.

[0055] The color filters 210 a , 210 b , and 210 c may be directly coated on the encapsulation layer 190 , or when an opposite substrate is applied, the color filters 210 a , 210 b , and 210 c may be disposed on one side or over the opposite substrate.

[0056] The light emitting device may include a first common layer CML1 141 between the reflective structure 111 serving as a first electrode and the light emitting layers R-EML, G-EML, and B-EML, and may include a second common layer CML2 142 between the light emitting layers R-EML, G-EML, and B-EML and the second electrode 170. The electron injection layer 160 may be formed directly below the second electrode 170. The electron injection layer 160 may include an inorganic material for improving electron injection efficiency and increasing reliability with respect to ultraviolet rays, and in this case, the electron injection layer 160 may include a source different from that of the second electrode 170 in a chamber for forming the second electrode 170.

[0057] The light emitting layers R-EML, G-EML, and B-EML may be selectively and individually formed in regions of the light emitting cells separated by the banks, and each light emitting cell may emit light having a corresponding color.

[0058] The first common layer CML1 141 may include a hole injection layer, a hole transport layer, an electron blocking layer, and the like, which are related to injection and transport of holes.

[0059] The second common layer CML2 142 may include a hole blocking layer, an electron transport layer, and the like.

[0060] Each or either of the first common layer CML1 141 and the second common layer CML2 142 may include a plurality of layers, and the first common layer CML1 and the second common layer CML2 may be formed together in the light emitting cell and may be integrally formed in the light emitting cell.

[0061] Hereinafter, the optical compensation structure 180 according to an embodiment of the present disclosure will be described.

[0062] Figures 2A-2C is a cross-sectional view of an example of an optical compensation structure according to various embodiments of the present disclosure.

[0063] like Figure 2A As shown, the optical compensation structure can be configured by stacking a first layer 181 with a high refractive index n2 and a second layer 182 with a low refractive index n1. In this case, the thickness of the second layer 182 with a low refractive index can be further increased, and in order to satisfy the destructive interference characteristic, the thickness of the second layer 182 can be 1.8 to 2.2 times greater than the thickness of the first layer 181.

[0064] like Figure 2B As shown, another optical compensation structure can be configured by stacking a low-refractive-index first layer 281 and a high-refractive-index second layer 282. In this case, the thickness of the low-refractive-index first layer 281 can be further increased, and in order to satisfy the destructive interference characteristic, the thickness of the first layer 281 can be approximately 1.8 to 2.2 times greater than the thickness of the second layer 282.

[0065] like Figure 2C As shown, another optical compensation structure may include a plurality of units 381 and 382 having low refractive index layers 381a, ..., 382b and high refractive index layers 381b, ..., 382a, while it is not necessary to alternately position the low refractive index layers and the high refractive index layers, and the lowest portion may correspond to the low refractive index layer 381a and may be aligned with the low refractive index layer 381a. Figure 1 The second electrode 170 contacts the uppermost portion, and the uppermost portion may contact the encapsulation layer 190. In this case, the thickness of the low refractive index layer may be further increased, and in order to satisfy the destructive interference characteristic, the thickness of the low refractive index layer may be 1.8 to 2.2 times greater than that of the high refractive index layer.

[0066] The above-described light-emitting display apparatus according to the present disclosure may be used to achieve a viewing angle with high brightness, and the internal light-emitting efficiency of the light-emitting device may be improved by destructive interference of the optical compensation structure 180 .

[0067] Thus, even if the reflective structure 111 used as the first electrode has a low reflectivity of 70% to 90%, this can be compensated by improving the emission function of the optical compensation structure 180, which can correspond to an alternative function of improving efficiency by using a reflective electrode with a high reflectivity of 99% in a structure without the optical compensation structure 180. The reflective structure 111 may include a metal such as aluminum, silver, a silver alloy, an aluminum alloy, etc., and may also include a high reflective alloy such as Ag-PD-Cu (APC). Other materials may also be used.

[0068] Figure 3 is a cross-sectional view of a light-emitting display device according to a second embodiment of the present disclosure. Figure 4 yes Figure 3 Cross-sectional view of a dielectric Bragg mirror. Figure 5A and Figure 5B Graph showing the principle of a dielectric Bragg mirror and its reflectivity.

[0069] exist Figure 3 In the light emitting display device according to the second embodiment of the present disclosure, the reflective structure 300 or the reflector of the light emitting device may be configured separately from the first electrode 120 .

[0070] Here, the reflective structure 300 can be formed as a metal reflector and can also contain an insulating dielectric material or a combination thereof.

[0071] When the reflective structure 300 is a metal reflector, the reflective structure 300 can have a thickness of 100 nm or can satisfy a condition expressed using the following Expression 3.

[0072] [Expression 3]

[0073] (n is a refractive index and k is an extinction coefficient)

[0074] The reflective structure 300 can contain an insulating dielectric material and can use the principle of a dielectric Bragg mirror (DBR).

[0075] As Figure 4 illustrated, the reflective structure 300 of the dielectric Bragg mirror can be configured by alternately arranging a high refractive index layer n A and a low refractive index layer n B , and as Figure 5A illustrated, the reflective structure 300 of the dielectric Bragg mirror can be a structure formed of a plurality of alternating material layers that periodically change in effective refractive index. The interface between the layers can cause partial reflection of light waves, and the reflectivity can be maximized in a specific wavelength range, as Figure 5B illustrated.

[0076] As Figure 3 illustrated, the light emitting display apparatus according to the second embodiment can share the reflective structure 300 of the Bragg reflector for light emitting cells, and to achieve uniform reflectivity in the visible spectrum, a peak wavelength for maximizing reflectivity can be determined in the green wavelength. For example, the peak wavelength can be 560 nm to 600 nm. When the refractive indices of the high refractive index layer n A and the low refractive index layer n B are n A and n B , the reflective structure 300 can be designed to satisfy the following Expressions 4 to 6.

[0077] [Expression 4]

[0078] mλ peak = 2(n A d A + n B d B ) λ = 560 nm to 600 nm

[0079] [Expression 5]

[0080] N: number of bayer (AB)

[0081] [Expression 6]

[0082]

[0083] According to the second embodiment, the reflective structure 300 of the dielectric Bragg mirror may be included in a light-emitting unit that emits light having different colors, and the reflective structure 300 is insulating, so a transparent electrode may be further formed on the reflective structure 300 to serve as the first electrode 120. The first electrode / transparent electrode 120 may have a thickness equal to or greater than 3 nm to serve as a reflective surface when light resonates in the light-emitting device.

[0084] Figure 6 is a cross-sectional view of a light-emitting display device according to a third embodiment of the present disclosure.

[0085] like Figure 6 As shown, the light-emitting display device according to the third embodiment of the present disclosure can be configured by applying different first reflective structures 310a, second reflective structures 310b and third reflective structures 310c to the red light-emitting unit, the green light-emitting unit and the blue light-emitting unit, respectively.

[0086] In this case, the light-emitting display device can be designed using the same expression so that Figure 3 and Figure 5B The red light emitting unit has a wavelength peak of 600nm to 660nm. Figure 3 and Figure 5B The green light emitting unit has a peak wavelength of 490nm to 550nm and Figure 3 and Figure 5B The mid-blue light emitting unit has a wavelength peak of 430nm to 490nm. However, because the wavelength peaks are different, the high refractive index layer and the low refractive index layer to be applied to the first reflective structure 310a, the second reflective structure 310b, and the third reflective structure 310c can be applied differently or separately.

[0087] Hereinafter, effects of the light emitting display device according to the present disclosure will be described.

[0088] In the following, in the first experimental example Ex1, it is not necessary to apply Figure 1 Instead of color filters and optical compensation structures, a high refractive index cover layer can be applied, and a polarizer can also be applied above the panel.

[0089] In the second experimental example Ex2, it is applicable Figure 1 The optical compensation structure is simple and does not require the application of color filters.

[0090] In each of the third experimental example Ex3 and the fourth experimental example Ex4, it is possible to apply Figure 1The optical compensation structure is provided, and color filters with different thicknesses can be applied. In this regard, in the third experimental example Ex3, a color filter with a thickness of 1.5 μm is applied, and in the fourth experimental example Ex4, a color filter with a thickness of 3.3 μm is applied.

[0091] Figures 7A-7C is a graph showing light emission characteristics with respect to each viewing angle of red, green, and blue in the first to fourth experimental examples Ex1 to Ex4.

[0092] As in Figures 7A-7C As shown in FIG, in the first experimental example Ex1, the tendency of decreasing luminance as the viewing angle changes is obvious in red, green, and blue. In contrast, in the second to fourth experimental examples Ex2 to Ex4, luminance does not necessarily decrease significantly even if the viewing angle changes.

[0093] Figures 8A-8C Graphs showing color luminance deviations Δu′v′ with respect to each viewing angle of red, green, and blue according to the first to fourth experimental examples.

[0094] like Figures 8A-8C As shown in FIG, in the first experimental example Ex1, color brightness deviation may be noticeable in red, green, and blue as the viewing angle changes. In contrast, in the third and fourth experimental examples Ex3 and Ex4, brightness does not necessarily decrease significantly even if the viewing angle changes.

[0095] Here, in addition to the attached Figures 7A-7C In the second experimental example Ex2, no filter is applied, so the tendency to reduce the panel brightness is not relatively greatly reduced, but color brightness deviation may occur, and in particular, it can be seen that Figure 8C For example, it can be seen that in the second experimental example Ex2, the color brightness deviation is large due to the reflection of external light.

[0096] Figures 9A-9C Graphs illustrating color coordinate fluctuations according to changes in viewing angle with respect to red, green, and blue according to the first to third experimental examples.

[0097] As from Figures 9A-9C It can be seen that in the first experimental example Ex1, as the viewing angle changes, specifically, from 0 degrees to 60 degrees, the distribution of the color coordinate change is wide.

[0098] In the second experimental example Ex2 and the third experimental example Ex3, the color coordinate fluctuation may be smaller when the viewing angle changes from 0 degrees to 65 degrees compared to the first experimental example Ex1. However, the second experimental example Ex2 and the third experimental example Ex3, in which no color filter is applied, may have a tendency of different color purity. Specifically, regarding Figure 9C The color coordinates of medium blue fluctuate, and in the second experimental example Ex2, the value of CIEy can change relatively from 0.06 to 0.08, but in the third experimental example Ex3, the fluctuation can be very small, from the level of 0.046 to 0.051, so it can be seen that high brightness characteristics are achieved despite the change in viewing angle.

[0099] Figure 10 : is a graph showing a change in transmittance for each wavelength in a structure to which a color filter is applied according to the third experimental example. Figure 11A and Figure 11B : is a graph showing EL spectra according to the second experimental example and the third experimental example.

[0100] As from Figure 10 It is seen that, in the third experimental example Ex3, the transmittance is high even if the viewing angle varies with respect to red, green, and blue.

[0101] Figure 11A The luminous intensity depending on the viewing angle when no color filter is applied as in the second experimental example Ex2 is shown. Figure 11B The luminous intensity depending on the viewing angle when a color filter is applied as in the third experimental example Ex3 is shown. In the second and third experimental examples, although the viewing angle changes with respect to blue, green, and red, peak characteristics can be present in the same wavelength, which means that the constant brightness in the second and third experimental examples Ex2 and Ex3 is maintained despite the change in the viewing angle.

[0102] Like in the third experimental example Ex3 and the fourth experimental example Ex4, a color filter instead of a polarizer can be applied to the light-emitting display device according to the embodiment of the present disclosure to prevent external light from being reflected, and therefore, the light-emitting display device according to the embodiment of the present disclosure can have excellent efficiency characteristics, can prevent the reduction in brightness, can limit color coordinate fluctuations, and can have high transmittance, as described in the third experimental example and the fourth experimental example.

[0103] The following description will refer to the fifth experimental example Ex5 and the sixth experimental example Ex6. In the fifth experimental example Ex5, the optical compensation structure according to the present disclosure is not applied, a high refractive index cover layer is applied, and a polarizer is applied thereon. In the sixth experimental example Ex6, the optical compensation structure is applied, and a color filter is applied thereon, as in Figure 1 Same as in.

[0104] [Table 1]

[0105]

[0106] In detail, in the fifth experimental example Ex5, an electrode having a high reflectance (99%) can be used as the first electrode of the light emitting device, the thickness ratio of the high refractive index cover layer and the low refractive index cover layer above the light emitting device is 2:1, and a package layer and a polarizer are sequentially applied thereon. In the sixth experimental example Ex6, a case in which an electrode having a low reflectance (70%) and an electrode having a high reflectance (99%) are used as the first electrode of the light emitting device is evaluated, and a case in which a first layer having a high refractive index and a second layer having a low refractive index are disposed as an optical compensation structure above the light emitting device and the second layer having a low refractive index is 1.8 times thicker than the first layer is evaluated. In the sixth experimental example Ex6, a package layer and a color filter can be applied above the optical compensation structure. In the sixth experimental example Ex6, the structure according to the first embodiment of the disclosure can be applied, and thus, as described above, it can be seen that excellent color purity, excellent white color lifetime, and excellent white color effective efficiency are achieved compared to the fifth experimental example Ex5.

[0107] As shown in Table 1 above, for example, the CIEy value of blue in the color coordinates in the fifth experimental example Ex5 is 0.053, and the CIEy value of blue in the color coordinates in the sixth experimental example Ex6 is 0.049, and thus the blue color purity in the sixth experimental example Ex6 is high.

[0108] In the sixth experimental example Ex6, even if a low reflectance metal is applied to the reflective structure used as the first electrode, the white color effective efficiency can be excellent, and the lifetime can also be excellent. In the sixth experimental example Ex6, even if a high reflectance metal is applied to the reflective structure, the white color efficiency can also be 146% based on the fifth experimental example Ex5, and thus, when the same electrode structure as the light emitting device of the fifth experimental example Ex5 is used, it can be seen that the color purity, the lifetime, and the effective efficiency are all excellent.

[0109] The importance of the light emitting display device through the above experiments will be described below.

[0110] In the case of gradual diversification of product groups, a device having a high brightness characteristic is required, which maintains high brightness despite a change in viewing angle to allow a user to view at different viewing angles.

[0111] However, when a configuration of a known package layer is used, the brightness tends to be severely reduced depending on a change in viewing angle.

[0112] The light-emitting display device according to the present disclosure can be designed to achieve destructive interference in such a manner that the optical compensation structure has reverse cavity characteristics, and it can be seen that the light-emitting display device has excellent brightness characteristics, high lifespan and high efficiency despite changes in viewing angle.

[0113] In this way, even if a metal with low reflectivity is used to form an electrode used as a reflective electrode, a predetermined efficiency or higher efficiency can be achieved, so there is no restriction on the use of the reflective electrode. For example, the degree of design freedom can be high.

[0114] The light-emitting display apparatus according to the present disclosure may apply a viewing angle structure for maximum brightness by maintaining an internal cavity in a top-emission type light-emitting device and applying a structure in which destructive interference occurs in all red, green, and blue colors by an upper optical compensation structure.

[0115] In addition, a color filter can be applied above the optical compensation structure instead of a polarizer, so color purity can be ensured, reflection of external light can be reduced to a level equal to or greater than 50%, and due to the structure without a polarizer, the effective efficiency can be improved to 50% level even in the destructive interference structure.

[0116] Based on the increase in effective efficiency, a lower low-reflection electrode of up to 70% can be designed, thereby increasing the contrast.

[0117] When the viewing angle structure for high brightness according to the present disclosure is used with a color filter, effective efficiency may correspond to a high brightness efficiency of 146% compared to a structure without the optical compensation structure according to the present disclosure.

[0118] Hereinafter, the light emitting display device according to the present disclosure will be described with respect to the configuration of thin film transistors (TFTs) on the substrate 100 .

[0119] Figure 12 is a diagram illustrating a light-emitting display device according to one or more embodiments of the present disclosure.

[0120] Reference Figure 12 , a configuration of a thin film transistor (TFT) connected to the first electrode 110 of a sub-pixel will be described.

[0121] A buffer layer 105 can be provided on the substrate 100, and a first semiconductor layer 1110 and a second semiconductor layer 1111 can be provided on the buffer layer 105. The buffer layer 105 can prevent impurities remaining on the substrate 100 from being introduced into the first semiconductor layer 1110 and the second semiconductor layer 1111. The first semiconductor layer 1110 and the second semiconductor layer 1111 can be amorphous or crystalline silicon semiconductor layers or transparent oxide semiconductor layers. Other types of semiconductors can be used. Opposite sides of the first semiconductor layer 1110 connected to the source 140 and the drain 1160, respectively, can be regions into which impurities are injected, and an intrinsic region between the impurity-injected regions of the first semiconductor layer 1110 can function as a channel region.

[0122] The first semiconductor layer 1110 and the second semiconductor layer 1111 can include at least one of an oxide semiconductor layer, a polysilicon layer, or an amorphous silicon layer.

[0123] The second semiconductor layer 1111 can be positioned to overlap the first storage electrode 1121 and the second storage electrode 1141 formed above, and can function as an auxiliary storage electrode for increasing the capacitance of a storage capacitor when impurities are injected therein. Alternatively, the second semiconductor layer 1111 can be omitted as needed or required.

[0124] The gate insulating layer 106 can be provided to cover the first semiconductor layer 1110 and the second semiconductor layer 1111, and the gate 1120 and the first storage electrode 1121 can be formed to cover intrinsic regions of the first semiconductor layer 1110 and the second semiconductor layer 1111.

[0125] A first interlayer insulating layer 107 can be provided to cover the first semiconductor layer 1110 and the second semiconductor layer 1111, the gate 1120, and the first storage electrode 1121.

[0126] Contact holes can be formed in opposite sides of the first semiconductor layer 1110 by selectively removing the first interlayer insulating layer 107 and the gate insulating layer 106, and the source 1140 and the drain 1160 can be connected to the first semiconductor layer 1110 through the contact holes, respectively. In the same process, the second storage electrode 1141 can be formed on the first interlayer insulating layer 107 to overlap the first storage electrode 1121.

[0127] Here, a first thin film transistor TFT for driving a light emitting device OLED included in a light emitting unit E can include a first semiconductor layer 1110 provided from a bottom to a top, a gate 1120 having a channel region overlapping a channel region of the first semiconductor layer 1110, and a source 1140 and a drain 1160 connected to opposite sides of the first semiconductor layer 1110, respectively.

[0128] The storage capacitor STC may include a first storage electrode 1121 and a second storage electrode 1141 that overlap each other with the first interlayer insulating layer 107 therebetween.

[0129] A second interlayer insulating layer 108 may be formed to cover the thin film transistor TFT and the storage capacitor STC.

[0130] Here, the thin film transistor TFT and the storage capacitor STC may include a light-shielding metal layer and may be disposed so as not to overlap with the transmission element T, and thus may overlap with the light-emitting element E (such as the red light-emitting element RE and the blue light-emitting element BE) or may overlap with a portion for forming the bank 150. Here, the bank 150 may be positioned between the transmission element T / E and the light-emitting element E, or may be positioned between the red light-emitting element RE and the blue light-emitting element BE, which are spaced apart from each other, of the light-emitting element E. In the case of the light-emitting element E, the first electrode 110, which is a reflective electrode, may prevent the metal layer disposed thereunder from being visible, and in the portion where the bank 150 is located, since the bank 150 having a relatively thick thickness is disposed, the components disposed thereunder may be prevented from being visible.

[0131] A planarization layer 109 may be further formed to planarize the surface covering the second interlayer insulating layer 108, and a contact portion CT1 may be formed by selectively removing the planarization layer 109 and the second interlayer insulating layer 108, so that the thin film transistor TFT and the first electrode 110 may be connected to each other through the contact portion CT1. Figure 12 A double-layer structure of the first reflective electrode 1101 and the first transparent electrode 1102 is shown, but the transparent electrode can be formed on the lower side and the upper side across the first reflective electrode. For example, the first reflective electrode of the first electrode 110 can include a reflective metal (e.g., aluminum, an aluminum alloy, silver, or a silver alloy), or can include an alloy of Ag-Pd-Cu (APC) to improve reflection efficiency.

[0132] The second electrode (cathode) 170 opposite to the first electrode 110 may include a reflective transmissive metal, for example, a magnesium alloy, a silver alloy, silver, magnesium, or MgAg. Although described as being formed of a metal or a metal alloy, the first electrode 110 may be a non-metallic material having conductivity. Transparent metals such as indium tin oxide (ITO) or indium zinc oxide (IZO) may also be used as needed. In addition, the first electrode may be formed of a plurality of layers including a first layer (or first reflective electrode) 1101 and a second layer (or first transparent electrode) 1102. The first layer 1101 and the second layer 1102 may be formed of different materials, but this is not required.

[0133] The light emitting display device according to the present disclosure may emit light through the second electrode 170 , and the optical compensation structure 180 may be disposed on the second electrode 170 to increase light output.

[0134] The organic stack OS between the first electrode 110 and the second electrode 170 can be configured together on the light-emitting unit E and the embankment 150 of the sub-pixel, but in the corresponding light-emitting units of the blue sub-pixel, the green sub-pixel and the red sub-pixel that emit light with different colors, at least the light-emitting layer can be patterned separately.

[0135] The structure including the substrate 100 and the thin film transistor array formed thereon will be referred to as a thin film transistor array substrate. In many cases, the substrate 100 can be formed as a transparent plastic film, but when a glass substrate is used, it can be used when the thickness of the glass substrate is small. Other transparent materials can be used for the substrate 100, but the substrate 100 does not need to be transparent.

[0136] Figure 13 is a cross-sectional view illustrating a display device according to a fourth embodiment of the present disclosure. Figure 14 yes Figure 13 A plan view of a display device.

[0137] like Figure 13 and Figure 14 As shown, the display device according to the present disclosure may further include a transmission unit T and light emitting units E1, E2 and E3. Figure 13 The display device provides a substrate 100, a reflective structure (reflective metal) 111, a hole transport layer HTL 131, a light emitting layer 132a, an electron transport layer ETL 133, an intermediate layer 134, an upper layer 240, a cathode 170, a color filter layer 200, and the like.

[0138] The configurations of the light emitting units E1 , E2 , and E3 are the same as those of the aforementioned light emitting units E according to the first to third embodiments, and thus descriptions thereof will be omitted.

[0139] The transmission unit T does not need to include at least one of a light emitting layer, a first electrode (eg, an anode), or a second electrode (anode).

[0140] The light-emitting display device disclosed herein may include: a substrate including a plurality of light-emitting units; a light-emitting layer located at the light-emitting units; a reflective structure located between the light-emitting layer and the substrate at the light-emitting units; a transmissive electrode located above the light-emitting layer and spanning a plurality of pixels on the substrate; an optical compensation structure in contact with the transmissive electrode, the optical compensation structure including at least one first layer having a first refractive index and at least one second layer having a second refractive index greater than the first refractive index, the first layer being thicker than the second layer; an encapsulation layer on the optical compensation structure; and a color filter on the encapsulation layer.

[0141] The optical compensation structure may have destructive interference characteristics, and the thickness of the first layer may be 1.8 to 2.2 times greater than the thickness of the second layer.

[0142] The optical compensation structure may include a plurality of first layers each having the first refractive index and a plurality of second layers having the second refractive index; and one of the plurality of first layers may contact the transmissive electrode and another one of the plurality of first layers may contact the encapsulation layer.

[0143] The thickness of each first layer may be 1.8 to 2.2 times greater than the thickness of each second layer.

[0144] The reflective structure may include a reflective metal having a thickness equal to or greater than 100 nm.

[0145] The light emitting display device may further include a transparent electrode disposed between the reflective metal and the light emitting layer and having a thickness smaller than that of the reflective metal.

[0146] The light-emitting display device may further include a first common layer and a second common layer disposed below and above the light-emitting layer, respectively, and the reflective metal may be in contact with the first common layer.

[0147] The reflective structure may be configured by alternately stacking a plurality of first refractive index layers and a plurality of second refractive index layers, the plurality of first refractive index layers and the plurality of second refractive index layers being different from each other.

[0148] Reflective structures can include expressions that satisfy relations of the metal, n is the refractive index and k is the extinction coefficient of the metal.

[0149] The light-emitting layer may include first to third light-emitting layers emitting light of different colors to different regions, the reflective structure includes first to third dielectric Bragg mirrors corresponding to the first to third light-emitting layers, respectively, and the dielectric Bragg mirrors satisfy the relational expression where n A is the refractive index of layer A, n B is the refractive index of layer B.

[0150] The light-emitting display device may further include a transparent electrode between the reflective structure and the light-emitting layer, and the transparent electrode may have a thickness equal to or greater than 3 nm, and the first to third dielectric Bragg mirrors may be located between the substrate and the transparent electrode.

[0151] Each of the first to third dielectric Bragg mirrors may include a plurality of third layers and a plurality of fourth layers that are alternately arranged, the fourth layers having a refractive index different from that of the third layers.

[0152] The light-emitting display device may further include a transmission unit on the substrate.

[0153] According to another embodiment, the light-emitting display device of the present disclosure may include: a substrate including a light-emitting unit and a transmission unit; a light-emitting device including a light-emitting layer at the light-emitting unit; an optical compensation structure located on the light-emitting device, including a first layer having a first refractive index and a second layer having a second refractive index, the first layer being thicker than the second layer; an encapsulation layer on the optical compensation structure; and a color filter on the encapsulation layer.

[0154] The thickness of the first layer may be 1.8 to 2.2 times greater than the thickness of the second layer.

[0155] The optical compensation structure may include a plurality of first layers and a plurality of second layers, respectively. One of the plurality of first layers may be in contact with the light emitting device and another one of the plurality of first layers may be in contact with the encapsulation layer.

[0156] The light emitting device may include a first electrode and a second electrode facing each other, a light emitting layer between the first electrode and the second electrode, a first common layer between the first electrode and the light emitting layer, and a second common layer between the light emitting layer and the second electrode. The first electrode includes a reflective layer.

[0157] The reflection layer can include the expression that satisfies the relation of the reflective electrodes, n is the refractive index and k is the extinction coefficient.

[0158] The light emitting display device may further include a transparent electrode between the reflective layer and the first common layer.

[0159] The reflection layer has the relational expression dielectric Bragg mirror.

[0160] The light emitting display device according to the present invention can have the following effects.

[0161] First, in the light-emitting display device according to the present disclosure, even if a metal with low reflectivity is used to form the reflective electrode, a predetermined efficiency or higher efficiency can be achieved, so there is no restriction on the use of the reflective electrode. In other words, the degree of design freedom is high.

[0162] Second, the light-emitting display device according to the present disclosure can apply a viewing angle structure for maximum brightness by maintaining an internal cavity in a top-emission type light-emitting device and applying a structure in which destructive interference occurs in all red, green, and blue colors by an upper optical compensation structure.

[0163] Third, a color filter instead of a polarizer can be applied above the optical compensation structure, therefore, color purity can be ensured, reflection of external light can be reduced to a level equal to or greater than 50%, and due to the structure without a polarizer, the effective efficiency can be increased to a level of 50% even in a destructive interference structure.

[0164] Fourth, based on the increase in effective efficiency, a lower low-reflection electrode with a reflectivity of up to 70% can be designed, thereby increasing the contrast.

[0165] Fifth, when the viewing angle structure for high brightness according to the present disclosure is used together with a color filter, effective efficiency may correspond to a high luminous efficiency of 146% compared to a structure without the optical compensation structure according to the present disclosure.

[0166] 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 modifications and variations of the present disclosure as long as they are within the scope of the appended claims and their equivalents.

[0167] CROSS-REFERENCE TO RELATED APPLICATIONS

[0168] This application claims the benefit of Korean Patent Application No. 10-2020-0190035, filed on December 31, 2020, which is hereby incorporated by reference as if fully set forth herein.

Claims

1. A light-emitting display device, comprising: a substrate comprising a plurality of light-emitting units; a light-emitting layer located at the light-emitting unit; a reflective structure located between the light-emitting layer and the substrate at the light-emitting unit; a transmissive electrode located above the light-emitting layer and spanning a plurality of pixels on the substrate; an optical compensation structure on the transmissive electrode and comprising a plurality of first layers having a first refractive index and a plurality of second layers having a second refractive index greater than the first refractive index; an encapsulation layer above the optical compensation structure; as well as a color filter above the encapsulation layer, wherein one of the plurality of first layers is in direct contact with the transmissive electrode, wherein another one of the plurality of first layers is in direct contact with the encapsulation layer, and The thickness of each of the plurality of first layers is 1.8 to 2.2 times greater than the thickness of one of the plurality of second layers.

2. The light-emitting display device according to claim 1, wherein The optical compensation structure has destructive interference characteristics.

3. The light-emitting display device according to claim 1, wherein The reflective structure includes a reflective metal having a thickness equal to or greater than 100 nm. 4 . The light-emitting display device according to claim 3 , further comprising a transparent electrode provided between the reflective metal and the light-emitting layer and having a thickness smaller than that of the reflective metal.

5. The light-emitting display device according to claim 3, further comprising: a first common layer and a second common layer respectively disposed below and above the light-emitting layer, Wherein, the reflective metal contacts the first common layer.

6. The light-emitting display device according to claim 1, wherein: The reflective structure is configured by alternately stacking a plurality of first refractive index layers and a plurality of second refractive index layers, the plurality of first refractive index layers and the plurality of second refractive index layers being different from each other.

7. The light-emitting display device according to claim 1, wherein: The reflection structure includes a relational expression satisfying of the metal, n is the refractive index of the metal and k is the extinction coefficient of the metal.

8. The light-emitting display device according to claim 1, wherein: The light-emitting layer includes a first light-emitting layer, a second light-emitting layer, and a third light-emitting layer that emit light of different colors to different regions. The reflective structure includes a first dielectric Bragg mirror, a second dielectric Bragg mirror, and a third dielectric Bragg mirror corresponding to the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer, respectively, and The dielectric Bragg mirror satisfies the relational expression Among them, n A is the refractive index of layer A, n B is the refractive index of layer B, and Δλ>320 nm.

9. The light-emitting display device according to claim 8, further comprising: a transparent electrode between the reflective structure and the light emitting layer, wherein the transparent electrode has a thickness equal to or greater than 3 nm, and The first to third dielectric Bragg mirrors are located between the substrate and the transparent electrode.

10. The light-emitting display device according to claim 8, wherein: Each of the first to third dielectric Bragg mirrors includes a plurality of third layers and a plurality of fourth layers that are alternately arranged, and a refractive index of each fourth layer is different from a refractive index of each third layer.

11. The light-emitting display device according to claim 1 , further comprising: A transmission unit is provided on the substrate.

12. A light-emitting display device, comprising: a substrate comprising a light emitting unit and a transmission unit located on different portions of the substrate; a light-emitting device comprising a light-emitting layer at the light-emitting unit; an optical compensation structure on the light emitting device and comprising a plurality of first layers having a first refractive index and a plurality of second layers having a second refractive index greater than the first refractive index; an encapsulation layer on the optical compensation structure; as well as a color filter on the encapsulation layer, wherein one of the plurality of first layers is in direct contact with the transmissive electrode on the light-emitting layer; wherein another one of the plurality of first layers is in direct contact with the encapsulation layer, and The thickness of each of the plurality of first layers is 1.8 to 2.2 times greater than the thickness of one of the plurality of second layers.

13. The light-emitting display device according to claim 12, wherein: The light emitting device comprises: a first electrode and a second electrode facing each other; the light-emitting layer located between the first electrode and the second electrode; a first common layer located between the first electrode and the light-emitting layer; and a second common layer located between the light-emitting layer and the second electrode, Wherein, the first electrode includes a reflective layer, and Wherein, the second electrode is the transmissive electrode.

14. The light-emitting display device according to claim 13, wherein: The reflective layer includes a relational expression satisfying of the reflective electrode, n is the refractive index of the reflective layer and k is the extinction coefficient of the reflective layer.

15. The light-emitting display device according to claim 13, further comprising: A transparent electrode is provided between the reflective layer and the first common layer.

16. The light-emitting display device according to claim 13, wherein: The reflective layer has a relationship satisfying the expression The dielectric Bragg mirror, where n A is the refractive index of layer A, n B is the refractive index of layer B, and Δλ>320 nm.

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