Organic light emitting display device including nanostructured mirror

Abstract

The organic light-emitting display device includes: a plurality of blue pixels configured to emit blue light; a plurality of green pixels configured to emit green light; and a plurality of red pixels configured to emit red light. Each of the plurality of blue pixels, the plurality of green pixels, and the plurality of red pixels includes: a reflective layer; a first electrode arranged on the reflective layer; a light-emitting region arranged on the first electrode; and a second electrode arranged on the light-emitting region. The upper surface of the reflective layer of the blue pixel is continuously flat, and the upper surface of the reflective layer of the green pixel and the upper surface of the reflective layer of the red pixel are flush with each other. Each of the green pixels or each of the red pixels includes a plurality of nanostructures protruding from the bottom surface of the reflective layer to the upper surface of the reflective layer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims the benefit of priority from Korean Patent Application No. 10-2019-0005851 filed in the Korean Intellectual Property Office on January 16, 2019, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The present disclosure relates to an organic light emitting display (OLED) device, and more particularly, to an organic light emitting display device including a nanostructure mirror that delays the phase of emitted light. Background Art

[0004] The organic light emitting display device includes red pixels, green pixels, and blue pixels, and can represent full colors by combining the pixels. Each pixel includes an organic light emitting device (OLED) and a plurality of thin film transistors driving the OLED.

[0005] OLED includes an organic emission layer between an anode and a cathode. The organic emission layer can emit red light, green light, blue light or white light. OLED can include a resonant structure suitable for each pixel to increase light extraction efficiency.

[0006] In an organic light-emitting display device including a plurality of OLEDs arranged in an array, the length of a microcavity for generating resonance suitable for each pixel is different. In order to manufacture an organic light-emitting display device, when the length of the microcavity is controlled to be suitable for each pixel, the height of an electrode and a light-emitting unit may vary from pixel to pixel, and thus the process of manufacturing the organic light-emitting display device is complicated.

[0007] In addition, since a light emitting material for emitting light suitable for each pixel is formed in a different manner, a manufacturing process of the light emitting unit may be complicated. Summary of the invention

[0008] An organic light emitting display device is provided, which includes microcavities formed differently from each other to resonate in different wavelength bands in each pixel by forming nanostructure mirrors at the same depth in a reflective layer having a reflective surface of the same plane.

[0009] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

[0010] According to one aspect of the present disclosure, a display device is provided, comprising: a plurality of blue pixels configured to emit blue light; a plurality of green pixels configured to emit green light; and a plurality of red pixels configured to emit red light, wherein each of the plurality of blue pixels, the plurality of green pixels, and the plurality of red pixels comprises: a reflective layer; a first electrode arranged on the reflective layer; a light-emitting region arranged on the first electrode; and a second electrode arranged on the light-emitting region, wherein an upper surface of the reflective layer of each of the plurality of blue pixels is continuously flat and flush with an upper surface of the reflective layer of the green pixel and an upper surface of the reflective layer of the red pixel, and wherein each of the plurality of green pixels or each of the plurality of red pixels comprises a plurality of nanostructures protruding a height from a bottom surface of the reflective layer to an upper surface of the reflective layer.

[0011] The height may be in the range of about 70 nm to about 80 nm.

[0012] The plurality of nanostructures may include circular pillars.

[0013] The nanostructures may be arranged periodically and regularly.

[0014] The first diameter and the first pitch of the circular pillars of the green pixels may be greater than the second diameter and the second pitch of the circular pillars of the red pixels.

[0015] The first diameter may be in a range of about 150 nm to about 250 nm, and the first pitch is in a range of about 350 nm to about 450 nm.

[0016] The second diameter may be in a range of about 50 nm to about 150 nm, and the second pitch is in a range of about 200 nm to about 300 nm.

[0017] The first electrode of each of the red pixel, the green pixel, and the blue pixel is separated from each other, and the second electrode is a common electrode.

[0018] The first electrode is a transparent electrode, and the second electrode is a semi-transparent electrode configured to reflect a portion of the light and transmit the rest of the light.

[0019] The second electrode may include a reflective metal and have a thickness in the range of about 10 nm to about 20 nm.

[0020] The reflective layer may include Ag, or an alloy including Ag.

[0021] The first electrode may be disposed in a region between the plurality of nanostructures.

[0022] The display device may further include: a dielectric material disposed in a region between the plurality of nanostructures.

[0023] The display device may further include: a dielectric layer disposed between the reflective layer and the first electrode, wherein the dielectric layer is disposed in a region between the nanostructures of the green pixel and the red pixel.

[0024] The light emitting region may include: a hole injection layer arranged on the first electrode; a hole transport layer arranged on the hole injection layer; an organic emission layer arranged on the hole transport layer and configured to generate blue light, green light and red light; an electron transport layer arranged on the organic emission layer; and an electron injection layer arranged on the electron transport layer.

[0025] The light emitting areas of the blue pixel, the green pixel, and the red pixel are formed continuously.

[0026] The light emitting area may be configured to emit white light.

[0027] The display device may further include: a cover layer disposed on the second electrode.

[0028] According to another aspect of the present disclosure, a display device is provided, comprising: a plurality of first pixels; and a plurality of second pixels, wherein each of the plurality of first pixels and the plurality of second pixels comprises: a reflective layer; a first electrode arranged on the reflective layer; a light-emitting area arranged on the first electrode; and a second electrode arranged on the light-emitting area, wherein the reflective layer of the plurality of first pixels has a uniform upper surface, and wherein the reflective layer of the plurality of second pixels has a non-uniform upper surface.

[0029] The non-uniform upper surface may include a plurality of nanostructure protrusions arranged on the bottom surface of the reflective layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] These and / or other aspects will become apparent and more easily understood through the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0031] Figure 1 is a schematic cross-sectional view of a structure of an organic light emitting display device including a nanostructure mirror according to an embodiment;

[0032] Figure 2 yes Figure 1 A schematic cross-sectional view of the structure of a reflective layer of a green pixel;

[0033] Figure 3 yes Figure 1 A schematic plan view of a reflective layer of a structure of a green pixel;

[0034] Figure 4 is a diagram showing example thicknesses of material layers of an organic light emitting display device according to an embodiment;

[0035] Figure 5is a simplified cross-sectional view of the structure of an organic light emitting display device according to a comparative example;

[0036] Figure 6 is a graph showing reflectance of emitted light of a display device according to a comparative example and reflectance of green light of an organic light emitting device according to an embodiment;

[0037] Figure 7 is a graph showing reflectance of emitted light of a display device according to a comparative example and reflectance of red light of an organic light emitting device according to an embodiment;

[0038] Figure 8 is a schematic cross-sectional view of a structure of an organic light emitting display device according to another embodiment; and

[0039] Fig. 9 is a schematic cross-sectional view of a structure of an organic light emitting display device according to another embodiment. DETAILED DESCRIPTION

[0040] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. In the accompanying drawings, the thickness of each layer or region may be exaggerated for clarity of the specification. The example embodiments described below may have different forms and should not be construed as being limited to the descriptions set forth herein.

[0041] It will also be understood that when an element is referred to as being “on” or “over” another element, the element can be directly in contact with the other element, or other intervening elements may be present.

[0042] Unless the context clearly indicates otherwise, the singular forms used herein are intended to include the plural forms as well. It should be understood that, unless otherwise defined, when a part “includes” or “comprises” an element in the specification, it does not exclude other elements but may further include other elements.

[0043] In the specification, the term "above" and similar directional terms may apply to both the singular and the plural.

[0044] With respect to the operations constituting the method, unless the order of the operations is clearly described or unless the context clearly indicates otherwise, the operations may be performed in any appropriate order. The operations may not necessarily be performed in order. All examples or example terms (e.g., etc.) are only used to explain the technical scope of the inventive concept in detail, and therefore the scope of the inventive concept is not limited by the examples or example terms as long as it is not limited by the claims.

[0045] Figure 1 is a schematic cross-sectional view of a structure of an organic light emitting display device 100 including a nanostructure mirror according to an embodiment.

[0046] Reference Figure 1, the organic light emitting display device 100 including the nanostructure mirror may include a blue pixel 100B, a green pixel 100G, and a red pixel 100R arranged on a substrate 110. Figure 1 In the figure, for the convenience of explanation, only one blue pixel 100B, one green pixel 100G and one red pixel 100R are depicted, but in fact, multiple blue pixels 100B, multiple green pixels 100G and multiple red pixels 100R may be repeatedly arranged. Multiple blue pixels 100B, multiple green pixels 100G and multiple red pixels 100R may be arranged in a two-dimensional (2D) array.

[0047] Each of the blue pixel 100B, the green pixel 100G, and the red pixel 100R may include a reflective layer 120, a dielectric layer 130, a first electrode 140, a light emitting region 150, and a second electrode 170 sequentially stacked on a substrate 110. A capping layer 180 may be additionally formed on the second electrode 170. The first electrode 140 may be an anode, and the second electrode 170 may be a cathode.

[0048] The light emitting region 150 may include a plurality of layers. For example, the light emitting region 150 may include a hole injection layer 151, a hole transport layer 152, an organic emission layer 153, an electron transport layer 154, and an electron injection layer 155 sequentially stacked on the first electrode 140. The organic emission layer 153 may include a blue emission layer, a green emission layer, and a red emission layer stacked sequentially. The organic emission layer 153 may emit white light. In this case, the manufacturing process of the organic emission layer 153 may be simplified.

[0049] However, the embodiment is not limited thereto. For example, the organic emission layer 153 may include a blue emission layer, a green emission layer, and a red emission layer, which are respectively arranged in the blue pixel 100B, the green pixel 100G, and the red pixel 100R.

[0050] According to another embodiment, the light emitting region 150 may include various additional layers as needed. For example, the light emitting region 150 may further include an electron blocking layer between the hole transport layer 152 and the organic emission layer 153 , and may further include a hole blocking layer between the organic emission layer 153 and the electron transport layer 154 .

[0051] Light may be generated from organic emission layer 153 by a combination of holes provided through hole injection layer 151 and hole transport layer 152 and electrons provided through electron injection layer 155 and electron transport layer 154. The wavelength of the generated light may be determined by the energy band gap of the light emitting material of organic emission layer 153.

[0052] The first electrode 140 may be a transparent electrode having the property of transmitting light (e.g., visible light), and may be used as an anode providing holes. The second electrode 170 arranged on the light emitting region 150 is a semi-transparent electrode that reflects a portion of the light and transmits the rest of the light, and may be used as a cathode providing electrons. The first electrode 140 may include a material having a relatively high work function, and the second electrode 170 may include a material having a relatively low work function. For example, the first electrode 140 may include a transparent conductive oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), or aluminum zinc oxide (AZO). The second electrode 170 may include a reflective metal having a very thin thickness. For example, the second electrode 170 may be a mixed layer of Ag and Mg or a mixed layer of Al and Li. The second electrode 170 may have a thickness in the range of 10nm to 20nm. Since the second electrode 170 has a very thin thickness, a portion of the light may pass through the second electrode 170.

[0053] The reflective layer 120 may constitute a microcavity together with the second electrode 170. A microcavity having a length L may be formed between the reflective layer 120 and the second electrode 170 of the organic light-emitting display device 100. For example, light generated from the light-emitting region 150 resonates by propagating back and forth between the reflective layer 120 and the second electrode 170, and then light corresponding to the resonant wavelength of the microcavity may be emitted to the outside through the second electrode 170.

[0054] The dielectric layer 130 may include an insulating material that is transparent to visible light. The dielectric layer 130 may include SiO2, SiNx, Al2O3, or HfO2. According to the refractive index of the dielectric layer 130, the resonant wavelength of the microcavity may be finely controlled. The upper surfaces of the dielectric layer 130 in the pixels 100B, 100G, and 100R may be formed to be coplanar. The dielectric layer 130 may be formed so that the structure formed thereon is planarized, and thus may be referred to as a planarization layer.

[0055] The cover layer 180 may be a passivation layer. The cover layer 180 may improve color purity and may improve resonance efficiency. The cover layer 180 may include a polymer. The cover layer 180 may include an organic material, such as N'-diphenylbenzidine (d-NPD) or N'-quaternary (4-methoxyphenyl) benzidine (MeO-TPD). However, the present embodiment is not limited thereto. For example, the cover layer 180 may include an inorganic insulating material.

[0056] The upper surface 120a of the reflective layer 120 of the blue pixel 100B may be flat. A nanostructure mirror to be described below is not formed on the reflective layer 120 of the blue pixel 100B.

[0057] The nanostructure mirror 125 is formed on the reflective layer 120 of the green pixel 100G and the reflective layer 120 of the red pixel 100R.

[0058] Figure 2 yes Figure 1 100G is a cross-sectional view of the reflective layer 120 of the green pixel 100G. Figure 3 yes Figure 1 FIG. 1 is a plan view of the reflective layer 120 of the green pixel 100G. Figure 2 and Figure 3 1 is a schematic diagram for explaining the nanostructure mirror 125 formed on the reflective layer 120 .

[0059] Reference Figures 1 to 3 , the upper surface 120a of the reflective layer 120 of the green pixel 100G and the upper surface 120a of the reflective layer 120 of the red pixel 100R may be formed to be flush with the upper surface 120a of the reflective layer 120 of the blue pixel 100B. That is, on the upper surface of the substrate 110, the height of the upper surface 120a of the reflective layer 120 of the green pixel 100G and the height of the upper surface 120a of the reflective layer 120 of the red pixel 100R may be equal to the height of the upper surface 120a of the reflective layer 120 of the blue pixel 100B.

[0060] The nanostructure mirror 125 including a plurality of nanostructures is formed to have a bottom surface 120b formed by etching the reflective layer 120 to a predetermined depth d from the upper surface 120a of the reflective layer 120. The nanostructure may be a circular column, but the embodiment is not limited thereto. The nanostructure may be a quadrilateral column, an elliptical column, or a polygonal column. Hereinafter, an embodiment in which the nanostructure is a circular column 127 is described.

[0061] The circular pillars 127 may be regularly and periodically arranged to have a 4-fold symmetry characteristic to prevent the microcavity from having polarization dependence. When the microcavity has polarization dependence, light of a specific polarization component may resonate, and thus the light emission efficiency of the organic light emitting display device 100 may be reduced.

[0062] The optical properties of the nanostructures may be determined by the diameter w, height d, and pitch p of the circular pillars 127. The diameter w, height d, and pitch p of the circular pillars 127 in each pixel region may be constant. The height d of the circular pillars 127 may be the depth of etching from the upper surface 120a of the reflective layer 120. In addition, the height d of the circular pillars 127 may be the height of the circular pillars 127 from the bottom surface 120b of the reflective layer 120.

[0063] When the nanostructures are polygonal pillars, the optical properties of the nanostructures may also be determined by the width, height, and spacing of the polygonal pillars.

[0064] As on the upper surface 120a of the reflective layer 120 of the green pixel 100G, a plurality of nanostructures are also formed on the upper surface 120a of the reflective layer 120 of the red pixel 100R. The shape of the nanostructure of the red pixel 100R may be similar to Figure 2 and Figure 3 The shape of the nanostructure of the green pixel 100G. The height of the nanostructure of the red pixel 100R may be equal to the height d of the nanostructure of the green pixel 100G. The diameter and the pitch of the nanostructure of the red pixel 100R may be smaller than the diameter w and the pitch p of the nanostructure of the green pixel 100G.

[0065] The resonant wavelength of the microcavity of each pixel can be determined by the optical length of the structure of the microcavity. For example, when the resonant wavelength of the microcavity is λ, the optical length of the microcavity can be nλ / 2 (where n is a natural number). The optical length of the microcavity can be determined by the sum of the optical thicknesses of the dielectric layer 130, the first electrode 140 and the light emitting region 150, the phase delay of the second electrode 170, and the phase delay of the nanostructure mirror 125 formed in the reflective layer 120. Here, the optical thickness of the dielectric layer 130, the first electrode 140 and the light emitting region 150 is not a simple physical thickness, but a thickness that takes into account the refractive index of the material of the dielectric layer 130, the first electrode 140 and the light emitting region 150. According to one embodiment, after fixing the optical thicknesses of the dielectric layer 130, the first electrode 140 and the light emitting region 150 and the phase delay of the second electrode 170, the optical length of the microcavity or the resonant wavelength of the microcavity can be controlled by controlling the phase delay of the reflective layer 120.

[0066] Since there is no nanostructure for phase delay on the upper surface 120 a of the reflective layer 120 of the blue pixel 100B, the resonance wavelength of the microcavity may be determined according to the design.

[0067] The resonant wavelength of the microcavity of the green pixel 100G may be determined by the diameter w, height d, and spacing p of the circular column 127. In other words, assuming that the resonant wavelength of the microcavity of the green pixel 100G is λ, the diameter w, height d, and spacing p of the circular column 127 may be selected so that the optical length of the microcavity L satisfies nλ / 2 (where n is a natural number). For example, the diameter w of the circular column 127 of the green pixel 100G may be in the range of 150nm to 250nm, the height d of the circular column 127 may be in the range of 70nm to 80nm, and the spacing p of the circular column 127 may be in the range of 350nm to 450nm. When the height w of the circular column 127 is less than 70nm, blue light may be emitted from the red pixel 100R, and thus the color purity of the organic light-emitting display device 100 may be reduced. When the height w of the circular column 127 is greater than 80nm, the light loss in the green pixel 100G may increase.

[0068] When the size of the circular pillars 127 is smaller than the resonant wavelength, the incident light may resonate around the circular pillars 127, thus forming an optical resonant nanostructure. In particular, the electric field component of the incident light may not penetrate into the space between the circular pillars 127, and only the magnetic field component may resonate around the circular pillars 127. Therefore, the optical resonant nanostructure formed in the space between the circular pillars 127 may be a magnetic resonator in the form of a cylinder, in which the magnetic component of the incident light resonates around the circular pillars 127. As a result, a larger phase delay than a simple phase delay caused by an effective optical distance (dxn) determined by multiplying the height d of the circular pillars 127 by the refractive index n of the circular pillars 127 may be generated in the circular pillars 127.

[0069] The resonant wavelength of the microcavity L of the red pixel 100R may be determined by the diameter w, height d, and pitch p of the circular column 127. In other words, assuming that the resonant wavelength of the microcavity L of the red pixel 100R is λ, the diameter w, height d, and pitch p of the circular column 127 may be selected so that the optical length of the microcavity L satisfies nλ / 2 (where n is a natural number). For example, the diameter w of the circular column 127 of the red pixel 100R may be in the range of 50 nm to 150 nm, the height d of the circular column 127 may be in the range of 70 nm to 80 nm, and the pitch p of the circular column 127 may be in the range of 200 nm to 300 nm.

[0070] According to another embodiment, the circular pillars 127 may have a 4-fold symmetry characteristic, but may be arranged irregularly or non-periodically.

[0071] Reference Figure 1 , the first electrodes 140 are separated from each other. The gap between the first electrodes 140 is filled with an insulating material 132. The insulating material 132 may be filled as the lowest layer (e.g., a hole injection layer) of the light emitting structure. However, the embodiment is not limited thereto. For example, the insulating material 132 may include a material such as a dielectric layer 130. The light emitting region 150 and the second electrode 170 may continuously cover the entire region of the organic light emitting display device 100 above the first electrode 140 without being separated from each other on the pixel. The second electrode 170 may be a common electrode. When a voltage is applied to the second electrode 170, light may be emitted from the corresponding pixel by selecting the first electrode 140, but the embodiment is not limited thereto. Together with the separation of the first electrode 140, the dielectric layer 130 and the reflective layer 120 may also be separated by being etched together with the first electrode 140.

[0072] Figure 4is a diagram showing example thicknesses of material layers of an organic light-emitting display device 100 according to an embodiment. The diameter, pitch, and depth (height) of the circular column of a green pixel are 225 nm, 400 nm, and 75 nm, respectively. The diameter, pitch, and depth (height) of the circular column of a red pixel are 100 nm, 225 nm, and 75 nm, respectively.

[0073] Figure 5 is a simplified cross-sectional view of the structure of an organic light emitting display device according to a comparative example. Figure 5 In the embodiment, the length of the microcavity between the reflective layer and the second electrode is different according to the pixel. The reflective layers of the blue pixel B, the green pixel G, and the red pixel R all have a flat surface. The reflective layers of the green pixel G and the red pixel are etched 40nm and 110nm respectively from the length of the microcavity of the blue pixel B.

[0074] Figure 6 is a curve showing the reflectivity of the emitted light of the display device according to the comparative example and the reflectivity of the green light of the organic light-emitting device according to the embodiment. The reflectivity indicates the amount of light emitted through the second electrode. The emitted light according to the comparative example has peaks of blue light (450nm), green light (520nm) and red light (620nm). As shown by the bold line, the green light according to the embodiment has a wavelength of about 520nm.

[0075] Reference Figure 6 Although the reflectivity of the green light according to the embodiment is relatively low when compared with the reflectivity of the green light according to the comparative example at a wavelength of about 520 nm, it can be seen that the green light according to the embodiment has a reflectivity that can be used for the light emitting area of ​​the organic light emitting display device.

[0076] Figure 7 is a graph showing the reflectivity of the emitted light of the display device according to the comparative example and the reflectivity of the red light of the organic light-emitting device according to the embodiment. The emitted light has peaks of blue light (450nm), green light (520nm) and red light (620nm), and the red light according to the embodiment is indicated by a thick line.

[0077] Reference Figure 7 Although the reflectivity of the red light according to the present embodiment is relatively low when compared with the reflectivity of the red light according to the comparative example at a wavelength of about 620 nm, it can be seen that the red light according to the present embodiment has a reflectivity that can be used in the light-emitting area of ​​the organic light-emitting display device.

[0078] Figure 8 is a schematic cross-sectional view of the structure of an organic light emitting display device 200 according to another embodiment. Figure 1 The elements are basically the same elements, and their description will be omitted.

[0079] Reference Figure 8 , the first electrode 140 is directly arranged on the reflective layer 120. The space between the circular columns 127 of the reflective layer 120 of the green pixel 100G and the red pixel 100R is filled with a dielectric layer 230. The first electrodes 140 are separated from each other by pixels, and the reflective layers 120 are separated from each other by pixels. The separated spaces of the first electrode 140 and the reflective layer 120 between the pixels are filled with an insulating material 232. The insulating material 232 may include a hole transport layer material or an insulating material. The insulating material may include SiO2, SiNx, Al2O3 or HfO2. The operation of the nanostructure mirror 125 formed in the reflective layer 120 can be well understood through the above embodiments, so its detailed description will be omitted. Since the reflective layer 120 and the first electrode 140 in the pixel are electrically connected, a voltage can be applied to the reflective layer 120 by applying a voltage to the first electrode 140.

[0080] Fig. 9 is a schematic cross-sectional view of the structure of an organic light emitting display device 300 according to another embodiment. Figure 1 The elements are basically the same elements, and their description will be omitted.

[0081] Reference Fig. 9 , the first electrode 340 is directly arranged on the reflective layer 120. The space between the circular pillars 127 of the green pixel 100G and the red pixel 100R on the bottom surface 120b of the reflective layer 120 is filled with an extended portion of the first electrode 340. The first electrode 340 and the reflective layer 120 are separated from each other by the pixel. The space separating the first electrode 340 and the reflective layer 120 between the pixels is filled with an insulating material 332.

[0082] The insulating material 332 may include a hole transport layer material or an insulating material. The insulating material may include SiO2, SiNx, Al2O3 or HfO2. The operation of the nanostructure mirror 125 formed in the reflective layer 120 may be well understood through the above embodiments, so its detailed description will be omitted. Since the reflective layer 120 and the first electrode 340 in the pixel are electrically connected, a voltage may be applied to the reflective layer 120 by applying a voltage to the first electrode 340.

[0083] In the organic light-emitting display device according to the embodiment, the upper surface of the reflective layer of the green pixel and the red pixel is flush with the upper surface of the reflective layer of the blue pixel, and in order to form the resonant wavelength of the green pixel and the resonant wavelength of the red pixel, nanostructure columns having the same height can be formed on the bottom surface of the reflective layer through a single patterning process, thereby simplifying the manufacturing process of the organic light-emitting display device.

[0084] In addition, the light emitting layer can emit white light, and thus the manufacturing of the light emitting layer of the organic light emitting display device can be simplified.

[0085] Although one or more embodiments have been described with reference to the drawings, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention as defined by the following claims.

Claims

1. A display device, comprising: a plurality of blue pixels configured to emit blue light; a plurality of green pixels configured to emit green light; and a plurality of red pixels configured to emit red light, each of the plurality of blue pixels, the plurality of green pixels, and the plurality of red pixels comprising: Reflective layer; A first electrode, arranged on the reflective layer; a light emitting region, arranged on the first electrode; and A second electrode is arranged on the light emitting area, The upper surface of the reflective layer of each of the plurality of blue pixels is continuously flat and flush with the upper surface of the reflective layer of the green pixel and the upper surface of the reflective layer of the red pixel, and Each of the plurality of green pixels or each of the plurality of red pixels includes a plurality of nanostructures protruding from a bottom surface of the reflective layer to an upper surface of the reflective layer by a certain height.

2. The display device according to claim 1, wherein: The height of the plurality of nanostructures ranges from 70 nm to 80 nm.

3. The display device according to claim 1, wherein: The plurality of nanostructures includes circular pillars.

4. The display device according to claim 3, wherein: The nanostructures are arranged periodically and regularly.

5. The display device according to claim 3, wherein: The first diameter and the first pitch of the circular columns of the green pixels are greater than the second diameter and the second pitch of the circular columns of the red pixels.

6. The display device according to claim 5, wherein: The first diameter is in the range of 150 nm to 250 nm, and the first pitch is in the range of 350 nm to 450 nm.

7. The display device according to claim 5, wherein: The second diameter is in the range of 50 nm to 150 nm, and the second pitch is in the range of 200 nm to 300 nm.

8. The display device according to claim 1, wherein: The first electrode of each of the red pixel, the green pixel, and the blue pixel is separated from each other, and the second electrode is a common electrode.

9. The display device according to claim 1, wherein: The first electrode is a transparent electrode, and the second electrode is a semi-transparent electrode configured to reflect a portion of light and transmit the rest of the light.

10. The display device according to claim 9, wherein: The second electrode includes a reflective metal and has a thickness in a range of 10 nm to 20 nm.

11. The display device according to claim 10, wherein: The reflective layer includes Ag or an alloy including Ag.

12. The display device according to claim 1, wherein: The first electrode is disposed in a region between the plurality of nanostructures.

13. The display device according to claim 1, further comprising: A dielectric material is disposed in regions between the plurality of nanostructures.

14. The display device according to claim 1, further comprising: a dielectric layer arranged between the reflective layer and the first electrode, The dielectric layer is arranged in a region between the nanostructures of the green pixel and the red pixel.

15. The display device according to claim 1, wherein: The light emitting area includes: a hole injection layer, arranged on the first electrode; a hole transport layer, disposed on the hole injection layer; an organic emission layer disposed on the hole transport layer and configured to generate blue light, green light, and red light; an electron transport layer disposed on the organic emission layer; and The electron injection layer is arranged on the electron transport layer.

16. The display device according to claim 1, wherein: The light emitting areas of the blue pixel, the green pixel, and the red pixel are formed continuously.

17. The display device according to claim 1, wherein: The light emitting region is configured to emit white light.

18. The display device according to claim 1, further comprising: A covering layer is arranged on the second electrode.

19. A display device comprising: a plurality of first pixels; as well as a plurality of second pixels, Wherein, each of the plurality of first pixels and the plurality of second pixels comprises: Reflective layer; A first electrode, arranged on the reflective layer; a light emitting region, arranged on the first electrode; and A second electrode is arranged on the light emitting area, The reflective layers of the plurality of first pixels have a uniform upper surface, and Wherein, the reflective layer of the plurality of second pixels has a non-uniform upper surface.

20. The display device according to claim 19, wherein: The non-uniform upper surface includes a plurality of nanostructure protrusions arranged on a bottom surface of the reflective layer.

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