Light-emitting device and display device including the same

Abstract

A light-emitting device is provided, comprising: a reflective layer including a phase modulation surface; a planarization layer disposed on the reflective layer; a first electrode disposed on the planarization layer; an organic emission layer disposed on the first electrode and configured to emit visible light including light of a first wavelength and light of a second wavelength shorter than the first wavelength; and a second electrode disposed on the organic emission layer; wherein the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and wherein the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2020 - 0026796, filed on March 3, 2020, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical field

[0003] Example embodiments of the present disclosure relate to a light - emitting device and a display device including the light - emitting device, and more particularly, to an organic light - emitting device and an organic light - emitting display device having high color purity without using a color filter. Background art

[0004] An organic light - emitting device (OLED) is a display device that forms an image by light emission according to the combination of holes supplied from an anode in an organic emission layer and electrons supplied from a cathode. The OLED has excellent display characteristics such as a wide viewing angle, a fast response speed, a thin thickness, a low manufacturing cost, and a high contrast ratio.

[0005] In addition, by selecting an appropriate material as the material of the organic emission layer, the OLED can emit a desired color. According to this principle, a color display device can be manufactured using an OLED. For example, the organic emission layer of a blue pixel may include an organic material that generates blue light, the organic emission layer of a green pixel may include an organic material that generates green light, and the organic emission layer of a red pixel may include an organic material that generates red light. Moreover, a white OLED can be manufactured by disposing a plurality of organic materials that respectively generate blue light, green light, and red light in one organic emission layer or by disposing two or more pairs of organic materials that are complementary to each other. Summary of the invention

[0006] One or more example embodiments provide a light - emitting device and a display device having high color purity without using a color filter by using a planarization layer including a microcavity having a phase - modulating surface and a light absorber.

[0007] Additional aspects will be set forth in part in the following description, and in part will become apparent from the description, or may be learned by practice of the example embodiments of the present disclosure.

[0008] According to one aspect of an exemplary embodiment, a light-emitting device is provided, including: a reflective layer including a phase-modulated surface; a planarization layer disposed on the reflective layer; a first electrode disposed on the planarization layer; an organic emission layer disposed on the first electrode and configured to emit visible light including light of a first wavelength and light of a second wavelength shorter than the first wavelength; and a second electrode disposed on the organic emission layer; wherein the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and wherein the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

[0009] The phase-modulated surface of the reflective layer may include a plurality of protrusions formed two-dimensionally periodically, and the resonance wavelength of the microcavity may be determined based on the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions.

[0010] When the first wavelength is λ, the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions may be set such that the optical length of the microcavity is equal to nλ / 2, where n is a natural number.

[0011] The phase-modulated surface of the reflective layer may further include a plurality of depressions formed two-dimensionally periodically.

[0012] The plurality of depressions may be configured to absorb the light of the second wavelength.

[0013] The plurality of protrusions and the plurality of depressions may contact the planarization layer.

[0014] Each of the plurality of protrusions and each of the plurality of depressions may have a cylindrical shape or a polygonal column shape.

[0015] The size of each of the plurality of protrusions and the size of each of the plurality of depressions may be smaller than the wavelength of visible light.

[0016] The diameter of each of the plurality of depressions may be less than or equal to 250 nm.

[0017] The difference between the diameter of each of the plurality of protrusions and the diameter of each of the plurality of depressions may be less than or equal to 100 nm.

[0018] The height of each of the plurality of protrusions and the depth of each of the plurality of depressions may be less than or equal to 100 nm.

[0019] The first electrode may be a transparent electrode, and the second electrode may be a semi-transmissive electrode configured to reflect a part of the light and transmit the remaining part of the light.

[0020] The second electrode may include a reflective metal, and the thickness of the second electrode may be 10 nm to 20 nm.

[0021] The planarization layer may include a material transparent to visible light, and a plurality of light absorbers may be dispersed in the planarization layer.

[0022] The visible light may be white light, the light of the first wavelength may include red light or green light, and the light of the second wavelength may include blue light.

[0023] The organic emission layer may include: a hole injection layer disposed on the first electrode; an organic emission material layer disposed on the hole injection layer; and an electron injection layer disposed on the organic emission material layer.

[0024] According to another aspect of the exemplary embodiment, a display device is provided, including: a first pixel configured to emit light of a first wavelength; a second pixel configured to emit light of a second wavelength different from the first wavelength; the first pixel including a reflective layer including a phase modulation surface; a planarization layer disposed on the reflective layer; a first electrode disposed on the planarization layer; an organic emission layer disposed on the first electrode and configured to emit visible light including light of the first wavelength and light of a second wavelength shorter than the first wavelength; and a second electrode disposed on the organic emission layer; wherein the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and wherein the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

[0025] The phase modulation surface of the reflective layer may include a plurality of protrusions formed two-dimensionally periodically, and the resonance wavelength of the microcavity may be determined by: the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions.

[0026] When the first wavelength is λ, the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions may be set such that the optical length of the microcavity is equal to nλ / 2, where n is a natural number.

[0027] The phase modulation surface of the reflective layer may further include a plurality of depressions formed two-dimensionally periodically.

[0028] The plurality of depressions may be configured to absorb the light of the second wavelength.

[0029] The plurality of protrusions and the plurality of depressions may contact the planarization layer.

[0030] The size of each of the plurality of protrusions and the size of each of the plurality of depressions may be smaller than the wavelength of visible light.

[0031] The second pixel may include: a reflective layer including a flat surface; a planarization layer disposed on the reflective layer of the second pixel; a first electrode disposed on the planarization layer of the second pixel; an organic emission layer disposed on the first electrode of the second pixel and configured to emit visible light, the visible light including light of a first wavelength and light of a second wavelength; and a second electrode disposed on the organic emission layer of the second pixel; wherein, the reflective layer of the second pixel and the second electrode of the second pixel form a microcavity configured to resonate the light of the second wavelength.

[0032] The planarization layer of the second pixel may not include a light absorber configured to absorb the light of the second wavelength.

[0033] The planarization layer of the second pixel may include a light absorber configured to absorb the light of the second wavelength.

[0034] The reflective layer of the first pixel and the reflective layer of the second pixel may extend continuously.

[0035] The planarization layer of the first pixel and the planarization layer of the second pixel may extend continuously.

[0036] The physical thickness of the first pixel and the physical thickness of the second pixel may be the same.

[0037] The visible light may be white light, the light of the first wavelength may include red light or green light, and the light of the second wavelength may include blue light.

[0038] The display device may further include a third pixel configured to emit light of a third wavelength different from the first wavelength and the second wavelength respectively. The third pixel may include: a reflective layer including a phase modulation surface; a planarization layer disposed on the reflective layer of the third pixel; a first electrode disposed on the planarization layer of the third pixel; an organic emission layer disposed on the first electrode of the third pixel and configured to emit visible light, the visible light including light of the first wavelength, light of the second wavelength, and light of the third wavelength; and a second electrode disposed on the organic emission layer of the third pixel; wherein, the reflective layer of the third pixel and the second electrode of the third pixel form a microcavity configured to resonate the light of the third wavelength.

[0039] The planarization layer of the third pixel may include a light absorber configured to absorb the light of the second wavelength shorter than the third wavelength.

[0040] The light absorber of the first pixel and the light absorber of the third pixel may include different materials.

[0041] The physical thickness of the first pixel, the physical thickness of the second pixel, and the physical thickness of the third pixel may be the same.

[0042] The visible light may be white light, the light of the first wavelength may include red light, the light of the second wavelength may include blue light, and the light of the third wavelength may include green light.

[0043] According to an aspect of an exemplary embodiment, there is provided a light-emitting device including: a reflective layer including a phase modulation surface including a plurality of protrusions and a plurality of depressions; a planarization layer disposed on the reflective layer; a first electrode disposed on the planarization layer; an organic emission layer disposed on the first electrode and configured to emit visible light including light of a first wavelength and light of a second wavelength shorter than the first wavelength; and a second electrode disposed on the organic emission layer; wherein the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and wherein the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

[0044] The resonance wavelength of the microcavity may be determined based on the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions, and the plurality of depressions may be configured to absorb the light of the second wavelength. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other aspects, features, and advantages of the exemplary embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0046] Figure 1 is a cross-sectional view schematically showing the structure of a light-emitting device according to an exemplary embodiment;

[0047] Figure 2 shows in more detail Figure 1 a cross-sectional view of an exemplary structure of the organic emission layer shown in

[0048] Figure 3 shows in more detail Figure 1 a cross-sectional view of another exemplary structure of the organic emission layer shown in

[0049] Figure 4 is schematically showing Figure 1 a perspective view of an exemplary structure of the reflective layer shown in

[0050] Figure 5 is schematically showing Figure 1 a perspective view of another exemplary structure of the reflective layer shown in

[0051] Figure 6 is a graph showing an example of the absorption characteristics of the planarization layer including the light absorber;

[0052] Figure 7 is a cross-sectional view showing the structure of a light-emitting device according to a first related example;

[0053] Figure 8 is a cross-sectional view showing the structure of a light-emitting device according to a second related example;

[0054] Figure 9 is a cross-sectional view showing the structure of a light-emitting device according to a third related example;

[0055] Figure 10 is a graph showing a comparison of the spectra of light emitted from the light-emitting devices according to the first to third related examples and the exemplary embodiment;

[0056] Figure 11 shows a comparison of the color coordinates of light emitted from the light-emitting devices according to the first to third related examples and the exemplary embodiment;

[0057] Figure 12 is a cross-sectional view schematically showing the structure of a light-emitting device according to another exemplary embodiment;

[0058] Figure 13 is schematically showing Figure 12 a perspective view of an exemplary structure of the reflection layer shown in;

[0059] Figure 14 is schematically showing Figure 12 a plan view of an exemplary structure of the reflection layer shown in;

[0060] Figure 15A schematically shows that light of a short wavelength flows into a recess formed in the reflection layer;

[0061] Figure 15B is schematically showing that light of a long wavelength is blocked in the reflection layer having the recess formed therein;

[0062] Figure 16 schematically shows light resonating in the light-emitting device according to the exemplary embodiment;

[0063] Figure 17 is schematically showing Figure 12 a plan view of another exemplary structure of the reflection layer shown in;

[0064] Figure 18 is schematically showing Figure 12 a perspective view of another exemplary structure of the reflection layer shown in;

[0065] Figure 19 is a cross-sectional view schematically showing the structure of a display device according to the exemplary embodiment;

[0066] Figure 20is a cross-sectional view schematically showing the structure of a display device according to another embodiment;

[0067] Figure 21 is a cross-sectional view schematically showing the structure of a display device according to another exemplary embodiment;

[0068] Figure 22 is a cross-sectional view schematically showing the structure of a display device according to another exemplary embodiment; and

[0069] Figure 23 is a cross-sectional view schematically showing the structure of a display device according to another exemplary embodiment. Detailed Description

[0070] Now, embodiments shown in the drawings will be described in detail, where like reference numerals always refer to like elements. In this regard, exemplary embodiments may have different forms and should not be construed as limited to the description set forth herein. Thus, the exemplary embodiments are described below only by referring to the drawings to explain various aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items. Expressions such as "at least one of..." modify the entire list of elements when following the list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0071] Hereinafter, a light-emitting device and a display device including the light-emitting device will be described in detail with reference to the drawings. The same reference numerals always denote the same elements, and in the drawings, the dimensions of the elements may be enlarged for clarity and ease of explanation. The exemplary embodiments described below are merely exemplary, and various modifications can be made according to the exemplary embodiments.

[0072] In the layer structures described below, the expressions "above..." or "on..." can include not only "directly on... in contact" but also "on... in a non-contact manner". Expressions in the singular form cover plural expressions, unless having a clearly different meaning in the context. It will also be understood that the terms "include" and / or "comprise" as used herein specify the presence of the described features or elements, but do not exclude the presence or addition of one or more other features or elements.

[0073] The use of "the (said)" and other similar indicators can correspond to both singular and plural forms. Unless the order of operations of the method according to the present disclosure is explicitly mentioned or described otherwise, the operations can be performed in an appropriate order. The present disclosure is not limited to the order of operations mentioned.

[0074] Terms such as "unit" or "module" used in the exemplary embodiments indicate a unit for processing at least one function or operation, and can be implemented in hardware or software or in a combination of hardware and software.

[0075] The connecting lines or connectors shown in the various drawings presented are intended to represent the functional relationships and / or physical or logical couplings between the various elements. It should be noted that there may be many alternative or additional functional relationships, physical connections, or logical connections in an actual device.

[0076] Unless otherwise required, the use of any and all examples or language provided herein is only intended to better illustrate the present disclosure and does not impose a limitation on the scope of the present disclosure.

[0077] Figure 1 is a cross-sectional view schematically showing the structure of a light-emitting device 100 according to an exemplary embodiment. Refer to Figure 1 , the light-emitting device 100 according to the exemplary embodiment may include: a reflective layer 110 having a phase-modulated surface; a transparent planarization layer 120 disposed on the reflective layer 110; a first electrode 131 disposed on the planarization layer 120; an organic emission layer 140 disposed on the first electrode 131; and a second electrode 132 disposed on the organic emission layer 140. The light-emitting device 100 may further include a transparent passivation layer 150 disposed on the second electrode 132 to protect the second electrode 132.

[0078] The light-emitting device 100 may be an organic light-emitting diode (OLED). For example, Figure 2 is a cross-sectional view showing in more detail an exemplary structure of the Figure 1 organic emission layer 140 shown in Figure 2 , the organic emission layer 140 may include: a hole injection layer 142 disposed on the planarization layer 120; an organic emission material layer 141 disposed on the hole injection layer 142; and an electron injection layer 143 disposed on the organic emission material layer 141. In this structure, holes provided by the hole injection layer 142 and electrons provided by the electron injection layer 143 may combine in the organic emission material layer 141 to generate light. The wavelength of the generated light can be determined according to the energy band gap of the light-emitting material of the organic emission material layer 141.

[0079] In addition, the organic emission layer 140 may further include a hole transport layer 144 disposed between the hole injection layer 142 and the organic emission material layer 141 to further facilitate the transport of holes. In addition, the organic emission layer 140 may further include an electron transport layer 145 disposed between the electron injection layer 143 and the organic emission material layer 141 to further facilitate the transport of electrons. In addition, the organic emission layer 140 may include various additional layers as needed. For example, the organic emission layer 140 may further include an electron blocking layer between the hole transport layer 144 and the organic emission material layer 141, and may further include a hole blocking layer between the organic emission material layer 141 and the electron transport layer 145.

[0080] The organic emission material layer 141 may be configured to emit visible light. For example, the organic emission material layer 141 may be configured to emit light in a band among the bands of red light, green light, and blue light. However, the embodiments are not limited thereto. For example, the organic light-emitting material layer 141 may be configured to emit white visible light including all of red light, green light, and blue light.

[0081] For example, Figure 3 is a cross-sectional view showing in more detail Figure 1 another exemplary structure of the organic emission layer 140 shown in Figure 3 . Referring to

[0082] The first electrode 131 disposed on the lower surface of the organic emission layer 140 may serve as an anode for providing holes. The second electrode 132 disposed on the upper surface of the organic emission layer 140 may serve as a cathode for providing electrons. To this end, the first electrode 131 may include a material having a relatively high work function, and the second electrode 132 may include a material having a relatively low work function.

[0083] In addition, the first electrode 131 may be a transparent electrode having the property of transmitting light (e.g., visible light). For example, the first electrode 131 may include a transparent conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), or aluminum zinc oxide (AZO).

[0084] The second electrode 132 may be a semi-transmissive electrode that reflects a part of the light and transmits the remaining part of the light. To this end, the second electrode 132 may include a very thin reflective metal. For example, the second electrode 132 may include a mixed layer of silver (Ag) and magnesium (Mg) or a mixed layer of aluminum (Al) and lithium (Li). The entire thickness of the second electrode 132 may be about 10 nm to about 20 nm. Since the thickness of the second electrode 132 is very thin, a part of the light can pass through the reflective metal.

[0085] The reflective layer 110 may be configured to reflect the light generated from the organic emission layer 140 and transmitted through the first electrode 131. To this end, the reflective layer 110 may include silver (Ag), gold (Au), aluminum (Al), or an alloy including silver (Ag), gold (Au), and aluminum (Al). However, the reflective layer 110 is not limited thereto, and may include other reflective materials.

[0086] The reflective layer 110 may be used to form a microcavity L together with the second electrode 132. For example, the microcavity L may be formed between the reflective layer 110 and the second electrode 132 of the light-emitting device 100. For example, the light generated from the organic emission layer 140 may reciprocate and resonate between the reflective layer 110 and the second electrode 132, and then, the light corresponding to the resonance wavelength of the microcavity L may be emitted to the outside through the second electrode 132.

[0087] The resonance wavelength of the microcavity L formed between the reflective layer 110 and the second electrode 132 may be determined by the optical length of the microcavity L. For example, when the resonance wavelength of the microcavity L is λ, the optical length of the microcavity L may be nλ / 2, where n is a natural number. The optical length of the microcavity L may be determined as the sum of the optical thicknesses of the layers forming the microcavity L between the reflective layer 110 and the second electrode 132, the phase delay caused by the second electrode 132, and the phase shift (e.g., phase delay) caused by the reflective layer 110. Here, the optical thickness of the layer forming the microcavity L between the reflective layer 110 and the second electrode 132 is not just the physical thickness, but the thickness considering the refractive index of the material of the layer forming the microcavity L. For example, the optical thickness of the layer forming the microcavity L may be the sum of the optical thicknesses of the planarization layer 120, the first electrode 131, and the organic emission layer 140.

[0088] According to an exemplary embodiment, the optical length or resonant wavelength of the microcavity L can be adjusted by adjusting only the phase shift caused by the reflective layer 110 while fixing the optical thickness of the layer forming the microcavity L and the phase delay caused by the second electrode 132. To control the phase shift caused by the reflective layer 110, a phase modulation surface contacting the planarization layer 120 can be formed on the reflective surface of the reflective layer 110. The phase modulation surface can include very small patterns at the nanoscale. For example, the phase modulation surface of the reflective layer 110 can have a meta-structure in which nano-patterns having a size smaller than the wavelength of visible light are periodically provided.

[0089] Referring again to Figure 1 , the reflective layer 110 can include a substrate 111 and a phase modulation surface formed on the upper surface 114 of the substrate 111. The phase modulation surface of the reflective layer 110 can include a plurality of protrusions 112 periodically formed on the upper surface 114 of the substrate 111. The plurality of protrusions 112 can have a columnar shape protruding from the upper surface 114 of the substrate 111. For example, the plurality of protrusions 112 can have a cylindrical shape. The plurality of protrusions 112 can be integrally formed with the substrate 111. The reflective layer 110 can be arranged such that the plurality of protrusions 112 contact the planarization layer 120.

[0090] When each of the protrusions 112 is, for example, cylindrical, the optical characteristics (e.g., phase delay of reflected light) of the phase modulation surface can be determined by: the diameter W of each of the protrusions 112, the height H of each of the protrusions 112, and the pitch P or period P of the plurality of protrusions 112. When each of the protrusions 112 is a polygonal column, the optical characteristics of the phase modulation surface can be determined by: the maximum width W of each of the protrusions 112, the height H of each of the protrusions 112, and the pitch or period P of the plurality of protrusions 112.

[0091] The diameter W, height H, and period P of the protrusions 112 can be constant with respect to the entire region of the phase modulation surface. For example, the diameter W of the protrusions 112 can be about 30 nm to 250 nm, the height H of the protrusions 112 can be about 0 nm to about 150 nm, and the period P of the plurality of protrusions 112 can be about 100 nm to about 300 nm.

[0092] As described above, when the size of each of the protrusions 112 of the phase modulation surface is smaller than the resonance wavelength, a plurality of nano-optical resonance structures can be formed while the incident light resonates around the protrusions 112. In particular, in the incident light, the electric field component may not penetrate into the space between the protrusions 112, and only the magnetic field component can resonate around the protrusions 112. Therefore, the plurality of nano-optical resonance structures formed in the space between the protrusions 112 can be cylindrical magnetic resonators, in which the magnetic field component of the incident light resonates around the protrusions 112. As a result, a phase shift greater than the simple phase shift caused by the effective optical distance (H×n) may occur on the phase modulation surface of the reflective layer 110, where the effective optical distance (H×n) is determined by the product of the height H of the protrusions 112 and the refractive index n of the protrusions 112.

[0093] Therefore, the resonance wavelength of the microcavity L can be determined by the following terms: the diameter W of each of the protrusions 112 of the phase modulation surface, the height H of each of the protrusions 112, and the period P of the plurality of protrusions 112. For example, when the resonance wavelength of the microcavity L is λ, the diameter W of each of the protrusions 112 of the phase modulation surface, the height H of each of the protrusions 112, and the period P of the plurality of protrusions 112 can be selected such that the optical length of the microcavity L satisfies nλ / 2, where n is a natural number. Then, the resonance wavelength of the microcavity L in the light emitting device 100 can be more easily matched with the emission wavelength or emission color of the light emitting device 100. For example, when the light emitting device 100 is a red light emitting device, the diameter W of each of the protrusions 112 of the phase modulation surface, the height H of each of the protrusions 112, and the period P of the plurality of protrusions 112 can be selected such that the resonance wavelength of the microcavity L corresponds to the red wavelength band. As described above, the emission wavelength of the light emitting device 100 can be determined only by the structure of the phase modulation surface of the reflective layer 110.

[0094] To prevent the microcavity L from having polarization dependence, the plurality of protrusions 112 can be regularly and periodically arranged to have a four-fold symmetry characteristic. When the microcavity L has polarization dependence, only light of a specific polarization component can resonate, which may deteriorate the light emitting efficiency of the light emitting device 100. For example, Figure 4 schematically shows Figure 1 a perspective view of an exemplary structure of the reflective layer 110 shown in Figure 5 schematically shows Figure 1 a perspective view of another exemplary structure of the reflective layer 110 shown in Figure 4 , a plurality of protrusions 112 having a cylindrical shape can be regularly arranged two-dimensionally on the upper surface 114 of the substrate 111. Additionally, referring to Figure 5 , a plurality of protrusions 112 having a square-column shape can be regularly arranged two-dimensionally on the upper surface 114 of the substrate 111. InFigure 4 and Figure 5 In Figure 4 and Figure 5 , although the protrusions 112 have a cylindrical shape and a square column shape, the shape of the protrusions 112 is not limited thereto. For example, the protrusions 112 may have an elliptical column or a polygonal column shape such as a pentagonal shape or a shape with more sides.

[0095] In addition, in Figure 4 and Figure 5 In Figure 4 and Figure 5 , the plurality of protrusions 112 are arranged in a regular two-dimensional array pattern. In this case, the interval between two adjacent protrusions 112 in the entire region of the phase modulation surface may be constant. However, if the plurality of protrusions 112 have a four-fold symmetry property, the plurality of protrusions 112 may be arranged in any other type of array. For example, the plurality of protrusions 112 may be arranged irregularly. In this case, the microcavity L may not have polarization dependence. Meanwhile, in another exemplary embodiment, the arrangement of the plurality of protrusions 112 may be designed to be different from the four-fold symmetry such that the light emitting device 100 intentionally emits only light of a specific polarization component. For example, the plurality of protrusions 112 may be arranged in a one-dimensional array pattern.

[0096] A planarization layer 120 may be provided on the reflective layer 110 having a phase modulation surface including a plurality of protrusions 112 to provide a flat surface. The lower surface of the planarization layer 120 may have a shape complementary to the phase modulation surface of the reflective layer 110, and its upper surface may have a flat shape. Therefore, the first electrode 131 provided on the upper surface of the planarization layer 120 may have a flat lower surface. Then, the first electrode 131 may apply a uniform electric field to the organic emission layer 140. The planarization layer 120 may include a material transparent to visible light. In addition, the planarization layer 120 may include an insulating material to prevent current from flowing from the first electrode 131 to the reflective layer 110. For example, the planarization layer 120 may include a metal oxide, a metal nitride, or a transparent polymer compound such as silicon dioxide (SiO2), silicon nitride (SiNx), aluminum oxide (Al2O3), or hafnium dioxide (HfO2).

[0097] Meanwhile, when considering the physical thickness of the organic emission layer 140, the optical length of the microcavity L can be selected to mainly utilize the second resonance. In other words, the optical length of the microcavity L can be selected to be the same as the emission wavelength λ of the light-emitting device 100, where n = 2 in nλ / 2. In this case, a part of the light having a wavelength shorter than the emission wavelength of the light-emitting device 100 can generate a third resonance, where n = 3, and can be emitted from the light-emitting device 100. For example, when the light-emitting device 100 is configured to emit red light, the optical length of the microcavity L can be selected to be 630 nm. In this case, a part of the light having a wavelength of 420 nm can generate a third resonance and can be emitted from the light-emitting device 100. Then, since blue light is emitted from the light-emitting device 100 together with red light, the color purity of the light emitted from the light-emitting device 100 can be reduced.

[0098] According to an exemplary embodiment, in order to suppress the emission of light having a wavelength shorter than the emission wavelength of the light-emitting device 100 from the light-emitting device 100, the planarization layer 120 may include a light absorber 121 that absorbs light in a wavelength band shorter than the wavelength emitted by the light-emitting device 100. The light absorber 121 may be selected to absorb, for example, light in the wavelength band that causes the third resonance in the microcavity L of the light-emitting device 100. Then, the light in the wavelength band that causes the second resonance in the microcavity L may not be absorbed by the light absorber 121 but may be emitted from the light-emitting device 100. Meanwhile, the light in the wavelength band that causes the third resonance in the microcavity L may be absorbed by the light absorber 121 in the planarization layer 120 during repeated passing through the planarization layer 120.

[0099] In Figure 1 , a plurality of light absorbers 121 are uniformly dispersed inside the planarization layer 120. In the planarization layer 120, only the material of the light absorber 121 may be separately mixed and dispersed, but the embodiment is not limited thereto. For example, the material of the light absorber 121 may be mixed with an organic binder and dissolved in an organic solvent, and then the organic solvent may be coated on the reflective layer 110 and cured by light or heat, thereby forming the planarization layer 120.

[0100] For example, Figure 6 is a graph showing an example of the absorption characteristics of the planarization layer 120 including the light absorber 121. In Figure 6 , a material that absorbs blue light is used as the light absorber 121, and while changing the concentration of the material of the light absorber 121 dissolved in the organic solvent, the change in the absorption characteristics of the planarization layer 120 is measured. In Figure 6 of the graph, the concentration represents the concentration of the material of the light absorber 121 before curing the organic solvent, and the absorption rate is measured after curing the organic solvent to form the planarization layer 120. Refer to Figure 6From the graph, it can be seen that the planarization layer 120 has an absorption peak near a wavelength of about 450 nm, and the absorption rate increases as the material of the light absorber 121 increases.

[0101] Figure 7 FIG. is a cross-sectional view showing the structure of the light-emitting device 10 according to the first related example. Refer to Figure 7 , the light-emitting device 10 according to the first related example may include a reflective layer 11, a planarization layer 12, a first electrode 13, an organic emission layer 14, a second electrode 15, and a passivation layer 16. Compared with the light-emitting device 100 according to the exemplary embodiment, the light-emitting device 10 is different in that the reflective layer 11 of the light-emitting device 10 does not have a phase modulation surface and the planarization layer 12 does not include a light absorber.

[0102] In addition, Figure 8 FIG. is a cross-sectional view showing the structure of the light-emitting device 20 according to the second related example. Refer to Figure 8 , the light-emitting device 20 according to the second related example may include a reflective layer 21 having a phase modulation surface 21a, a planarization layer 22, a first electrode 23, an organic emission layer 24, a second electrode 25, and a passivation layer 26. Compared with the light-emitting device 100 according to the exemplary embodiment, the light-emitting device 20 is different in that the planarization layer 22 of the light-emitting device 20 does not include a light absorber.

[0103] In addition, Figure 9 FIG. is a cross-sectional view showing the structure of the light-emitting device 30 according to the third related example. Refer to Figure 9 , the light-emitting device 30 according to the third related example may include a reflective layer 31, a planarization layer 32 including a light absorber 32a, a first electrode 33, an organic emission layer 34, a second electrode 35, and a passivation layer 36. Compared with the light-emitting device 100 according to the exemplary embodiment, the light-emitting device 30 is different in that the reflective layer 31 of the light-emitting device 30 does not have a phase modulation surface.

[0104] Figure 10 FIG. is a graph showing a comparison of the spectra of light emitted from the light-emitting devices 10, 20, 30, and 100 according to the first related example to the third related example and the exemplary embodiment. All of the light-emitting devices 10, 20, 30, and 100 according to the first related example to the third related example and the exemplary embodiment select the optical length of the microcavity such that a second resonance occurs in the red light band. Figure 10 The graph of shows that the intensity of the blue light emitted from the light-emitting device 10 according to the first related example is the greatest. In addition, the intensities of the blue light emitted from the light-emitting devices 20 and 30 according to the second related example and the third related example are similar to each other. In the light-emitting device 100 according to the exemplary embodiment, the emission of blue light is greatly reduced.

[0105] In addition, Figure 11 shows a comparison of the color coordinates of the light emitted from the light-emitting devices 10, 20, 30, and 100 according to the first to third related examples and the exemplary embodiment. Figure 11 The color coordinates shown in are the CIE 1934 color coordinates. Figure 11 shows that the light emitted from the light-emitting device 100 according to the exemplary embodiment is closest to pure red light. Then, as the color of the emitted light gradually approaches blue light, the color purity of the emitted light deteriorates in the order of the third related example, the second related example, and the first related example.

[0106] As described above, according to the exemplary embodiment, by appropriately configuring the phase modulation surface, the light-emitting device 100 including the microcavity can more easily match the resonance wavelength of the microcavity with the emission wavelength of the light-emitting device 100. In addition, since the planarization layer 120 provided on the phase modulation surface includes a light absorber that absorbs light having a component of a wavelength other than the target light emission wavelength (for example, light having a component of another wavelength that causes the third resonance in the microcavity), the light-emitting device 100 can emit only the light of the target emission wavelength component and suppress the light of the remaining wavelength components. Therefore, the light-emitting device 100 can achieve higher color purity.

[0107] Figure 12 is a cross-sectional view schematically showing the structure of a light-emitting device 200 according to another exemplary embodiment. Refer to Figure 12 , the light-emitting device 200 according to another exemplary embodiment may include: a reflective layer 210 including a phase modulation surface; a planarization layer 220 provided on the reflective layer 210 and including a light absorber 221; a first electrode 231 provided on the planarization layer 220; an organic emission layer 240 provided on the first electrode 231; and a second electrode 232 provided on the organic emission layer 240. In addition, the light-emitting device 200 may further include a transparent passivation layer 250 provided on the second electrode 232. Compared with Figure 1 the light-emitting device 100 shown in, the structure of the phase modulation surface formed on the reflective layer 210 of the light-emitting device 200 shown in Figure 12 is different from the structure of the phase modulation surface of the light-emitting device 100 shown in Figure 1 . Figure 12 The remaining configuration of the light-emitting device 200 shown in is the same as that of the light-emitting device 100 shown in Figure 1 , and thus the description thereof will be omitted.

[0108] Figure 13 is a perspective view schematically showing an exemplary structure of the reflective layer 210 shown in Figure 12 , Figure 14 is a plan view schematically showing an exemplary structure of the reflective layer 210 shown in Figure 12 . Refer toFigures 12 to 14 , the phase modulation surface may include a plurality of protrusions 212 and a plurality of depressions 213 that are periodically disposed on the upper surface 214 of the substrate 211 facing the first electrode 231. The reflective layer 210 may be disposed such that the plurality of protrusions 212 and the plurality of depressions 213 are in contact with the planarization layer 220.

[0109] The size of each of the protrusions 212 protruding from the upper surface 214 of the substrate 211 and the size of each of the depressions 213 recessed from the upper surface 214 of the substrate 211 may be smaller than the wavelength of visible light. As Figure 13 and Figure 14 shown, the protrusions 212 and the depressions 213 may be formed to be spaced apart, and the area occupied by the upper surface 214 may be larger than the area occupied by the plurality of protrusions 212 or the plurality of depressions 213. Additionally, the area occupied by each of the protrusions 212 may be greater than or equal to the area occupied by each of the depressions 213.

[0110] The plurality of protrusions 212 may be periodically arranged on the upper surface 214 of the substrate 211 at a predetermined pitch P1. Figure 14 An example is shown in which the protrusions 212 are periodically arranged in the shape of a square array. However, this is only an example, and additionally, the plurality of protrusions 212 may be arranged in arrays of various other shapes such as equilateral triangles, regular hexagons, etc. Each of the protrusions 212 may have, for example, a diameter W1 of about 300 nm or less. However, each of the protrusions 212 is not limited thereto. For example, each of the protrusions 212 may have a diameter W1 of about 30 nm to 250 nm. Additionally, each of the protrusions 212 may have, for example, a height H1 of about 100 nm or less. However, these values are only examples.

[0111] As described above, the plurality of protrusions 212 can be used to adjust the optical length of the microcavity L so that light corresponding to the emission wavelength of the light-emitting device 200 resonates. For example, when the resonance wavelength of the microcavity L is λ, the diameter W1 and height H1 of each of the protrusions 212 of the phase modulation surface and the pitch P1 of the protrusions 212 can be selected such that the microcavity L satisfies nλ / 2, where n is a natural number.

[0112] The plurality of depressions 213 may be formed on the upper surface 214 of the substrate 211 at a predetermined depth H2. The plurality of depressions 213 may be two-dimensionally and periodically arranged between the plurality of protrusions 212 at a predetermined pitch P2. Figure 13 and Figure 14An example of each of the recesses 213 disposed between two adjacent protrusions 212 is shown. Each of the recesses 213 may be formed in a cylindrical shape. The diameter W2 of each of the recesses 213 may be, for example, about 250 nm or less. More specifically, for example, the diameter W2 of each of the recesses 213 may be about 80 nm to 250 nm, but is not limited thereto. In addition, the depth H2 of each of the recesses 213 may be, for example, about 100 nm or less, but this is only an example. Additionally, the difference between the diameter W1 of each of the protrusions 212 and the diameter W2 of each of the recesses 213 may be, for example, about 100 nm or less, but is not limited thereto.

[0113] The plurality of recesses 213 may be used to absorb light having wavelengths that are not desired to resonate within the microcavity L. Figure 15A Schematically shown is that light of a short wavelength flows into the recesses 213 formed in the reflective layer 210. Figure 15B Schematically shown is that light of a long wavelength is blocked in the reflective layer 210 in which the recesses 213 are formed. As Figure 15A shown, light of a short wavelength flows into the nanoscale recesses 213 formed in the upper surface 214 of the substrate 211 and is absorbed in the recesses 213, while as Figure 15B shown, light of a long wavelength does not flow into the recesses 213 and is reflected from the upper surface 214 of the substrate 211.

[0114] The wavelength of the light absorbed into the recesses 213 formed in the reflective layer 210 may vary according to the size of the recesses 213. For example, when the protrusions 212 are not considered, recesses 213 having a diameter of about 190 nm formed on the surface of a flat reflective layer 210 including silver (Ag) may absorb blue light having a wavelength of 450 nm, and recesses 213 having a diameter of about 244 nm may absorb green light having a wavelength of 550 nm.

[0115] As described above, in the light-emitting device 200 configured to emit red light, when the optical length of the microcavity L is selected to be 630 nm, a part of the light having a wavelength of 420 nm may cause a third resonance to occur from the light-emitting device 200. Then, since blue light is emitted from the light-emitting device 200 together with red light, the color purity of the light emitted from the light-emitting device 200 is reduced. In an exemplary embodiment, light having wavelengths that are not desired to resonate may be absorbed by the light absorber 221 in the planarization layer 220. Additionally, by forming a plurality of nanoscale recesses 213 and a plurality of protrusions 212 on the phase modulation surface of the reflective layer 210, light having wavelengths that are not desired to resonate may be additionally absorbed by the recesses 213. Accordingly, the color purity of the light-emitting device 200 may be further improved.

[0116] Figure 16Schematically shows the light resonating in the light-emitting device 200 according to an exemplary embodiment. In Figure 16 , the red light-emitting device is shown as the light-emitting device 200 as an example, and for convenience, only the reflective layer 210 and the second electrode 232 constituting the microcavity L are shown. Referring to Figure 16 , in the microcavity L, the red light R may not flow into the recess 213 formed in the surface of the reflective layer 210, but may be reflected from the surface of the reflective layer 210. However, it can be seen that the blue light B having a wavelength shorter than the red light R flows into the recess 213 formed in the surface of the reflective layer 210 and is absorbed in the recess 213. As described above, each of the recesses 213 may have a diameter of, for example, about 250 nm or less. Therefore, in the microcavity L, only the red light R can resonate and be emitted to the outside of the light-emitting device 200.

[0117] According to an exemplary embodiment, the light-emitting device 200 may be a green light-emitting device. Generally, in the case where the surface of the reflective layer has a flat structure, when the second resonance of green light occurs in the microcavity, the third resonance of ultraviolet light occurs, and this third resonance does not affect the display device in the visible light region. However, when using the reflective layer 210 having a phase-modulated surface, due to the phase modulation, it is possible to have the third resonance of the blue light B in the microcavity L. In addition, since the optical length varies according to the refractive index and thickness of the planarization layer 220, the resonance wavelength may change. Therefore, the blue light B having an undesired short wavelength in the green light-emitting device may be emitted. Therefore, even when the light-emitting device 200 is a green light-emitting device, it is possible to further suppress the undesired emission of the blue light B by forming a plurality of recesses 213 in the surface of the reflective layer 210 and dispersing the light absorbers 221 in the planarization layer 220.

[0118] As described above, by forming a plurality of recesses 213 in the phase-modulated surface of the reflective layer 210 and dispersing the light absorbers 221 in the planarization layer 220, it is possible to resonate and emit the light having a long wavelength with a desired resonance (for example, red light or green light), and to absorb the light having an undesired short wavelength (for example, blue light), so that the color purity can be further improved.

[0119] Figure 17 is a plan view schematically showing another exemplary structure of the Figure 12 shown reflective layer 210. In Figure 13 and Figure 14 in the exemplary embodiment shown, the protrusions 212 are periodically arranged in a square array, and each of the recesses 213 may be formed between two adjacent protrusions 212. In Figure 17In the reflective layer 210 shown in [reference], the protrusions 212 protruding from the upper surface 214 of the substrate 211 may be periodically arranged in a square array, and the recesses 213 may be arranged at a predetermined depth between two adjacent protrusions 212 that are arranged adjacent to each other in the diagonal direction on the upper surface 214 of the substrate 211. In other words, each of the recesses 213 may be disposed at the center of a unit array having a square shape including four adjacent protrusions 212. However, this is merely an example, and the protrusions 212 and the recesses 213 may be arranged in various other shapes.

[0120] In addition, Figure 18 is a perspective view schematically showing Figure 12 another exemplary structure of the reflective layer 210 shown in [reference]. In Figure 13 and Figure 14 in the exemplary embodiment shown in [reference], the protrusions 212 have a cylindrical shape, and the recesses 213 are formed in a cylindrical shape. In Figure 18 the reflective layer 210 of the metal shown in [reference], the protrusions 212 have a square column shape. In this case, the maximum width of the protrusions 212 may correspond to the diameter. In addition, the recesses 213 may be formed in a cylindrical shape between two adjacent protrusions 212. However, this is merely an example, and each of the protrusions 212 may have various other polygonal prism shapes, such as a triangular prism or a pentagonal prism. In addition, each of the recesses 213 may also be formed in various other shapes.

[0121] The above-described light-emitting devices 100 and 200 may be applied to a plurality of pixels of a display device. Figure 19 is a cross-sectional view schematically showing the structure of a display device 1000 according to an exemplary embodiment. Referring to Figure 19 , the display device 1000 may include a plurality of pixels that emit light of different colors. Here, the plurality of pixels may include red pixels 1100, green pixels 1200, and blue pixels 1300 that are arranged adjacent to each other on the same plane of the substrate. For example, for convenience, only one unit pixel including the red pixel 1100, the green pixel 1200, and the blue pixel 1300 is shown.

[0122] The red pixel 1100 may have the same as Figure 1The same structure as the light-emitting device 100 shown in []. The red pixel 1100 may include: a first reflective layer 1110 including a first phase modulation surface; a first planarization layer 1120 disposed on the first reflective layer 1110; a first electrode 1131 disposed on the first planarization layer 1120; an organic emission layer 1140 disposed on the first electrode 1131; and a second electrode 1132 disposed on the organic emission layer 1140. The red pixel 1100 may further include a transparent passivation layer 1150 disposed on the second electrode 1132. The first reflective layer 1110 may include a plurality of first protrusions 1112 formed to protrude from the upper surface 1114 of the substrate 1111. The first reflective layer 1110 may form a first microcavity that resonates red light R together with the second electrode 1132. Moreover, the first planarization layer 1120 may include a light absorber 1121 that absorbs blue light B.

[0123] The green pixel 1200 may have the same structure as Figure 1 the light-emitting device 100 shown in []. The green pixel 1200 may include: a second reflective layer 1210 including a second phase modulation surface; a second planarization layer 1220 disposed on the second reflective layer 1210; a first electrode 1131 disposed on the second planarization layer 1220; an organic emission layer 1140 disposed on the first electrode 1131; a second electrode 1132 disposed on the organic emission layer 1140; and a passivation layer 1150 disposed on the second electrode 1132. The second reflective layer 1210 may include a plurality of second protrusions 1212 formed to protrude above the upper surface 1214 of the substrate 1211. The second reflective layer 1210 may form a second microcavity that resonates green light G together with the second electrode 1132. In the case of the green pixel 1200, the second planarization layer 1220 may not include a light absorber.

[0124] In addition, the blue pixel 1300 may include: a third reflective layer 1310; a third planarization layer 1320 disposed on the third reflective layer 1310; a first electrode 1131 disposed on the third planarization layer 1320; an organic emission layer 1140 disposed on the first electrode 1131; a second electrode 1132 disposed on the organic emission layer 1140; and a passivation layer 1150 disposed on the second electrode 1132. The upper surface of the third reflective layer 1310 in the blue pixel 1300 may include a flat reflective surface. Moreover, the third planarization layer 1320 may not include a light absorber.

[0125] The third reflective layer 1310 may form a third microcavity, and the third microcavity and the second electrode 1132 resonate the blue light B. By adjusting the structure and optical characteristics of the layer disposed between the third reflective layer 1310 and the second electrode 1132, the third microcavity may have a resonance wavelength of the blue light B. Here, the upper surface of the third reflective layer 1310 may be formed to have the same height as the upper surfaces of the first protrusions 1112 of the first phase modulation surface and the second protrusions 1212 of the second phase modulation surface. The third reflective layer 1310 may have a third phase modulation surface having a resonance wavelength of the blue light B. In this case, the third phase modulation surface may include a plurality of protrusions protruding at a predetermined height on the upper surface of the third reflective layer 1310.

[0126] In the display device 1000 according to an exemplary embodiment having the above structure, the first reflective layer 1110, the second reflective layer 1210, and the third reflective layer 1310 of the adjacent red pixel 1100, green pixel 1200, and blue pixel 1300 may continuously extend. Moreover, the first planarization layer 1120, the second planarization layer 1220, and the third planarization layer 1320 may also continuously extend with each other. Moreover, the first electrodes 1131 of the red pixel 1100, green pixel 1200, and blue pixel 1300 may integrally extend. For example, the first electrode 1131 may be a common electrode. In order to independently drive the adjacent red pixel 1100, green pixel 1200, and blue pixel 1300, the organic emission layers 1140 and the second electrodes 1132 of the red pixel 1100, green pixel 1200, and blue pixel 1300 may be separated from each other. For example, the second electrode 1132 may be a pixel electrode. In addition, the red pixel 1100, green pixel 1200, and blue pixel 1300 may include the same organic emission layer 1140. In this case, the organic emission layer 1140 may be configured to emit white light.

[0127] In the red pixel 1100, among the white light generated in the organic emission layer 1140, the red light R may reciprocate and resonate between the first reflective layer 1110 and the second electrode 1132, and then may be emitted to the outside through the second electrode 1132. At this time, among the white light generated in the organic emission layer 1140, the blue light B may be absorbed by the light absorber 1121 in the first planarization layer 1120, so that the red light R with improved color purity may be emitted in the red pixel 1100.

[0128] In the green pixel 1200, in the white light generated from the organic emission layer 1140, the green light G can reciprocate and resonate between the second reflective layer 1210 and the second electrode 1132, and then can be emitted to the outside through the second electrode 1132. Additionally, in the blue pixel 1300, in the white light generated in the organic emission layer 1140, the blue light B can reciprocate and resonate between the third reflective layer 1310 and the second electrode 1132, and then can be emitted to the outside through the second electrode 1132.

[0129] According to the exemplary embodiment, the red pixel 1100 and the green pixel 1200 may respectively include a first phase modulation surface having a plurality of first protrusions 1112 and a second phase modulation surface having a plurality of second protrusions 1212, wherein the plurality of first protrusions 1112 and the plurality of second protrusions 1212 are smaller than the wavelength of the incident light and are periodically arranged, and the resonance of a desired wavelength can be more easily caused by adjusting the size and pitch of the first protrusions 1112 and the second protrusions 1212. Thus, in order to adjust the optical length of the microcavity in each of the red pixel 1100, the green pixel 1200, and the blue pixel 1300, it may not be necessary to separately adjust the physical thickness of each of the red pixel 1100, the green pixel 1200, and the blue pixel 1300, and only the first phase modulation surface of the red pixel 1100 and the second phase modulation surface of the green pixel 1200 may be separately configured. Then, the physical thicknesses of the red pixel 1100, the green pixel 1200, and the blue pixel 1300 may all be the same. Additionally, the upper surfaces of the first protrusions 1112 and the second protrusions 1212 in the red pixel 1100 and the green pixel 1200 may be formed to have the same height as the upper surface of the third reflective layer 1310 in the blue pixel 1300. Thus, the display device 1000 can be more easily manufactured. Additionally, the light absorber 1121 in the first planarization layer 1120 of the red pixel 1100 can absorb the blue light B, and thus the color purity of the red light R emitted from the red pixel 1100 can be improved.

[0130] Figure 20 is a cross-sectional view schematically showing the structure of a display device 2000 according to another exemplary embodiment. In Figure 20In the case of the display device 2000 shown, the second planarization layer 1220 of the green pixel 1200 may further include a light absorber 1121 that absorbs blue light B. Then, the color purity of the green light G emitted from the green pixel 1200 can be improved. Here, the light absorber 1121 provided on the first planarization layer 1120 of the red pixel 1100 and the light absorber 1121 provided on the second planarization layer 1220 of the green pixel 1200 may include the same material or different materials. For example, the light absorber 1121 provided on the first planarization layer 1120 of the red pixel 1100 may be selected as a material that does not absorb red light R, and the light absorber 1121 provided on the second planarization layer 1220 of the green pixel 1200 may be selected as a material that does not absorb green light G.

[0131] In addition, Figure 21 is a cross-sectional view schematically showing the structure of a display device 3000 according to another exemplary embodiment. In Figure 21 the display device 3000 shown, the planarization layers of all pixels may include a light absorber 1121 that absorbs blue light B. In other words, the light absorber 1121 formed of the same material that absorbs blue light B may be dispersed in the first planarization layer 1120 of the red pixel 1100, the second planarization layer 1220 of the green pixel 1200, and the third planarization layer 1320 of the blue pixel 1300. Then, the first planarization layer 1120 of the red pixel 1100, the second planarization layer 1220 of the green pixel 1200, and the third planarization layer 1320 of the blue pixel 1300 can be formed more simply in a single process.

[0132] As Figure 21 shown, in the blue pixel 1300, the distance between the upper surface of the third reflective layer 1310 and the lower surface of the first electrode 1131 may be the shortest. In the red pixel 1100, the distance between the upper surface 1114 of the base 1111 of the first reflective layer 1110 and the lower surface of the first electrode 1131 may be the longest. Therefore, in the third planarization layer 1320 of the blue pixel 1300, since the path through which the blue light B passes is the shortest, the loss of the blue light B caused by the light absorber 1121 in the third planarization layer 1320 may be relatively small. In addition, in the first planarization layer 1120 of the red pixel 1100, since the path through which the blue light B passes is the longest, the blue light B can be sufficiently absorbed by the light absorber 1121 in the first planarization layer 1120.

[0133] Figure 22 is a cross-sectional view schematically showing the structure of a display device 4000 according to another exemplary embodiment. Refer to Figure 22, the first reflective layer 1110 of the red pixel 1100 of the display device 4000 may further include a plurality of first recesses 1113 that absorb blue light B. The second reflective layer 1210 of the green pixel 1200 may include only the second protrusion 1212. Therefore, both the first recesses 1113 and the light absorber 1121 in the red pixel 1100 can absorb blue light B, and thus the color purity of the red light R emitted from the red pixel 1100 can be improved.

[0134] In addition, Figure 23 is a cross-sectional view schematically showing the structure of a display device 5000 according to another exemplary embodiment. Refer to Figure 23 , the first reflective layer 1110 of the red pixel 1100 of the display device 5000 may further include a plurality of first recesses 1113 that absorb blue light B, and the second reflective layer 1210 of the green pixel 1200 may further include a plurality of second recesses 1213 that absorb blue light B.

[0135] In Figure 22 and Figure 23 , only the red pixel 1100 includes the light absorber 1121, but is not limited thereto. For example, in the exemplary embodiment shown in Figure 20 , in the exemplary embodiments of Figure 22 and Figure 23 , the red pixel 1100 and the green pixel 1200 may include the light absorber 1121. Moreover, in the exemplary embodiment shown in Figure 21 , in the exemplary embodiments of Figure 22 and Figure 23 , the red pixel 1100, the green pixel 1200, and the blue pixel 1300 may all include the light absorber 1121.

[0136] It should be understood that the exemplary embodiments described herein should be considered merely descriptive and not for limiting purposes. The description of the features or aspects in each exemplary embodiment should typically be regarded as applicable to other similar features or aspects in other embodiments.

[0137] Although the exemplary embodiments have been described with reference to the accompanying drawings, those of ordinary skill in the art will understand that various changes in form and detail can be made without departing from the spirit and scope defined by the claims.

Claims

1. A light-emitting device, comprising: A reflective layer including a phase modulation surface, the phase modulation surface including a plurality of protrusions formed two-dimensionally periodically and a plurality of depressions formed two-dimensionally periodically; A planarization layer disposed on the reflective layer; A first electrode disposed on the planarization layer; An organic emission layer disposed on the first electrode and configured to emit visible light, the visible light including light of a first wavelength and light of a second wavelength shorter than the first wavelength; And A second electrode disposed on the organic emission layer; Wherein, the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and Wherein, the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

2. The light-emitting device according to claim 1, wherein The resonant wavelength of the microcavity is determined based on the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions.

3. The light-emitting device according to claim 2, wherein, When the first wavelength is λ, the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions are set such that the optical length of the microcavity is equal to nλ / 2, where n is a natural number.

4. The light-emitting device according to claim 1, wherein The plurality of depressions are configured to absorb the light of the second wavelength.

5. The light-emitting device according to claim 1, wherein, The plurality of protrusions and the plurality of depressions contact the planarization layer.

6. The light-emitting device according to claim 1, wherein, Each of the plurality of protrusions and each of the plurality of depressions has a cylindrical shape or a polygonal column shape.

7. The light-emitting device according to claim 1, wherein The size of each of the plurality of protrusions and the size of each of the plurality of depressions are smaller than the wavelength of the visible light.

8. The light-emitting device according to claim 7, wherein, The diameter of each of the plurality of depressions is less than or equal to 250 nm.

9. The light-emitting device according to claim 7, wherein, The difference between the diameter of each of the plurality of protrusions and the diameter of each of the plurality of depressions is less than or equal to 100 nm.

10. The light-emitting device according to claim 7, wherein, The height of each of the plurality of protrusions and the depth of each of the plurality of depressions are less than or equal to 100 nm.

11. The light-emitting device according to claim 1, wherein, The first electrode is a transparent electrode, and the second electrode is a semi-transmissive electrode configured to reflect a part of the light and transmit the remaining part of the light.

12. The light-emitting device according to claim 11, wherein, The second electrode includes a reflective metal, and Wherein, the thickness of the second electrode is 10 nm to 20 nm.

13. The light-emitting device according to claim 1, wherein, The planarization layer includes a material transparent to the visible light, and Wherein, a plurality of light absorbers are dispersed in the planarization layer.

14. The light-emitting device according to claim 1, wherein, The visible light is white light, the light of the first wavelength includes red light or green light, and the light of the second wavelength includes blue light.

15. The light-emitting device according to claim 1, wherein, The organic emission layer includes: A hole injection layer disposed on the first electrode; An organic emission material layer disposed on the hole injection layer; and An electron injection layer disposed on the organic emission material layer.

16. A display device, comprising: A first pixel configured to emit light of a first wavelength; And A second pixel configured to emit light of a second wavelength different from the first wavelength, The first pixel includes: A reflective layer including a phase modulation surface, the phase modulation surface including a plurality of protrusions formed two-dimensionally periodically and a plurality of depressions formed two-dimensionally periodically; A planarization layer disposed on the reflective layer; A first electrode disposed on the planarization layer; An organic emission layer disposed on the first electrode and configured to emit visible light, the visible light including light of the first wavelength and light of a second wavelength shorter than the first wavelength; and A second electrode disposed on the organic emission layer; Wherein, the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and Wherein, the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

17. The display device according to claim 16, wherein, The resonant wavelength of the microcavity is determined by: the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions.

18. The display device according to claim 17, wherein, When the first wavelength is λ, the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions are set such that the optical length of the microcavity is equal to nλ / 2, where n is a natural number.

19. The display device according to claim 16, wherein, The plurality of depressions are configured to absorb the light of the second wavelength.

20. The display device according to claim 16, wherein, The plurality of protrusions and the plurality of depressions contact the planarization layer.

21. The display device according to claim 16, wherein, The size of each of the plurality of protrusions and the size of each of the plurality of depressions are smaller than the wavelength of the visible light.

22. The display device according to claim 16, wherein, The second pixel includes: A reflective layer including a flat surface; A planarization layer disposed on the reflective layer of the second pixel; A first electrode disposed on the planarization layer of the second pixel; An organic emission layer disposed on the first electrode of the second pixel and configured to emit the visible light, the visible light including the light of the first wavelength and the light of the second wavelength; and A second electrode disposed on the organic emission layer of the second pixel, Wherein, the reflective layer of the second pixel and the second electrode of the second pixel form a microcavity configured to resonate the light of the second wavelength.

23. The display device according to claim 22, wherein, The planarization layer of the second pixel does not include a light absorber configured to absorb the light of the second wavelength.

24. The display device according to claim 22, wherein, The planarization layer of the second pixel includes a light absorber configured to absorb the light of the second wavelength.

25. The display device according to claim 22, wherein, The reflective layer of the first pixel and the reflective layer of the second pixel extend continuously.

26. The display device according to claim 22, wherein The planarization layer of the first pixel and the planarization layer of the second pixel extend continuously.

27. The display device according to claim 22, wherein, The physical thickness of the first pixel and the physical thickness of the second pixel are the same.

28. The display device according to claim 22, wherein, The visible light is white light, the light of the first wavelength includes red light or green light, and the light of the second wavelength includes blue light.

29. The display device according to claim 16, further comprising: A third pixel configured to emit light of a third wavelength different from the first wavelength and the second wavelength respectively, The third pixel includes: A reflective layer including a phase modulation surface; A planarization layer disposed on the reflective layer of the third pixel; A first electrode disposed on the planarization layer of the third pixel; An organic emission layer, disposed on the first electrode of the third pixel and configured to emit visible light, the visible light including light of the first wavelength, light of the second wavelength, and light of the third wavelength; and A second electrode, disposed on the organic emission layer of the third pixel, wherein a reflective layer of the third pixel and the second electrode of the third pixel form a microcavity configured to resonate the light of the third wavelength.

30. The display device according to claim 29, wherein, The planarization layer of the third pixel includes a light absorber configured to absorb the light of the second wavelength that is shorter than the third wavelength.

31. The display device according to claim 30, wherein, The light absorbers of the first pixel and the third pixel include different materials.

32. The display device according to claim 29, wherein, The physical thicknesses of the first pixel, the second pixel, and the third pixel are the same.

33. The display device according to claim 29, wherein, The visible light is white light, the light of the first wavelength includes red light, the light of the second wavelength includes blue light, and the light of the third wavelength includes green light.

34. A light-emitting device, comprising: A reflective layer including a phase modulation surface, the phase modulation surface including a plurality of protrusions and a plurality of depressions; A planarization layer, disposed on the reflective layer; A first electrode, disposed on the planarization layer; An organic emission layer, disposed on the first electrode and configured to emit visible light, the visible light including light of a first wavelength and light of a second wavelength shorter than the first wavelength; and A second electrode, disposed on the organic emission layer; wherein the reflective layer and the second electrode form a microcavity configured to resonate the light of the first wavelength, and wherein the planarization layer includes a light absorber configured to absorb the light of the second wavelength.

35. The light-emitting device according to claim 34, wherein, Determining the resonance wavelength of the microcavity based on the width or diameter of each of the plurality of protrusions, the height of each of the plurality of protrusions, and the distance between the plurality of protrusions, and wherein the plurality of depressions are configured to absorb the light of the second wavelength.

Images