Light emitting device and display apparatus including the same

Abstract

Provided is a light-emitting device including: a reflective layer including a plurality of nanostructures regularly two-dimensionally disposed and a low-refractive layer disposed adjacent to the plurality of nanostructures; a first electrode disposed on the reflective layer; an organic emission layer disposed on the first electrode; and a second electrode disposed on the organic emission layer, wherein each of the plurality of nanostructures includes a non-metallic material, and the low-refractive layer includes a dielectric material having a second refractive index lower than a first refractive index of the non-metallic material.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0096945, filed on August 3, 2020, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] The exemplary embodiments of this disclosure relate to light-emitting devices and display devices including light-emitting devices, and more specifically to organic light-emitting devices and organic light-emitting display devices that have high color purity without the use of color filters. Background Technology

[0004] Display devices, including those using organic light-emitting diodes (OLEDs), form images when holes injected from the anode and electrons injected from the cathode combine in an organic emitting layer to emit light. OLEDs offer superior display characteristics such as wide viewing angles, fast response times, thinness, low manufacturing costs, and high contrast.

[0005] Furthermore, OLEDs can emit light of desired colors by selecting appropriate materials as the organic emitting layer. Based on this principle, color display devices can be realized using OLEDs. For example, the organic emitting layer of blue pixels can be formed from organic materials that produce blue light, the organic emitting layer of green pixels can be formed from organic materials that produce green light, and the organic emitting layer of red pixels can be formed from organic materials that produce red light. Moreover, white OLEDs can be realized by arranging multiple organic materials that produce blue, green, and red light respectively in a single organic emitting layer, or by arranging two or more pairs of complementary organic materials. Summary of the Invention

[0006] One or more example embodiments provide a light-emitting device and a display device including the light-emitting device, and more specifically, an organic light-emitting device and an organic light-emitting display device that have high color purity without the use of a color filter.

[0007] Additional aspects will be set forth in part in the description which follows, and will become clear in part from the description itself, or may be learned by practical example embodiments.

[0008] According to one aspect of an example embodiment, a light-emitting device is provided, comprising: a reflective layer including a plurality of nanostructures regularly arranged in two dimensions and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; a first electrode disposed on the reflective layer; an organic emitting layer disposed on the first electrode; and a second electrode disposed on the organic emitting layer, wherein each of the plurality of nanostructures comprises a nonmetallic material, and the low-refractive-index layer comprises a dielectric material having a second refractive index lower than a first refractive index of the nonmetallic material.

[0009] The first electrode may be a transparent electrode, and the second electrode may be a semi-transparent electrode configured to reflect a portion of the light and transmit the remainder of the light.

[0010] The non-metallic material may include dielectric material or semiconductor material.

[0011] The dielectric material may include at least one of TiO2, BaTiO3, Cr2O3, HfO2 and SiNx.

[0012] The semiconductor material may include at least one of Si, ZnS, ZnSe, GaP, InP, GaAs, GaN, and AlAs2.

[0013] The reflective layer and the second electrode can form a microcavity with a resonant wavelength.

[0014] The diameter of each of the plurality of nanostructures in the reflective layer, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures can be determined such that the reflective layer has the highest reflectivity for light with a wavelength corresponding to the resonant wavelength of the microcavity.

[0015] The period of the plurality of nanostructures can be smaller than the resonant wavelength of the microcavity.

[0016] The period of the multiple nanostructures can range from 200 nm to 500 nm.

[0017] The height of each of the plurality of nanostructures can range from 20 nm to 200 nm.

[0018] The top surface of the low refractive index layer can be disposed on the top surface of the plurality of nanostructures, the top surface of the plurality of nanostructures can be spaced apart from the first electrode, and the top surface of the low refractive index layer can directly contact the first electrode.

[0019] The top surfaces of the plurality of nanostructures and the top surface of the low-refractive-index layer can be disposed on the same plane, and the top surfaces of the plurality of nanostructures and the top surface of the low-refractive-index layer can directly contact the first electrode.

[0020] The reflective layer may further include a metal reflective film, which is flat and directly contacts the bottom surface of the plurality of nanostructures.

[0021] The low refractive index layer can be disposed on the top surface of the metal reflective film that does not contact the bottom surface of the plurality of nanostructures, and can also be disposed on the bottom surface of the metal reflective film.

[0022] The reflective layer may further include a metal reflective film, which is flat and disposed on the bottom surface of the low refractive index layer.

[0023] The low refractive index layer may include: a first low refractive index layer disposed on the bottom surface of the plurality of nanostructures and a second low refractive index layer disposed on the side and top surfaces of the plurality of nanostructures, wherein the first low refractive index layer and the second low refractive index layer may include dielectric materials with different refractive indices.

[0024] According to another aspect of an example embodiment, a display device is provided, 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, wherein the first pixel comprises: a reflective layer comprising a plurality of regularly arranged nanostructures in a two-dimensional manner and a low refractive index layer disposed adjacent to the plurality of nanostructures; a first electrode disposed on the reflective layer; an organic emitting layer disposed on the first electrode and configured to emit visible light including the first wavelength and the second wavelength; and a second electrode disposed on the organic emitting layer, wherein each of the plurality of nanostructures comprises a nonmetallic material, and the low refractive index layer comprises a dielectric material having a second refractive index lower than the first refractive index of the nonmetallic material.

[0025] The first electrode may be a transparent electrode, and the second electrode may be a semi-transparent electrode configured to reflect a portion of the light and transmit the remainder of the light.

[0026] The non-metallic material may include dielectric material or semiconductor material.

[0027] The dielectric material may include at least one of TiO2, BaTiO3, Cr2O3, HfO2 and SiNx.

[0028] The semiconductor material may include at least one of Si, ZnS, ZnSe, GaP, InP, GaAs, GaN, and AlAs2.

[0029] The diameter of each of the plurality of nanostructures in the reflective layer, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures can be determined such that the reflective layer of the first pixel has the highest reflectivity for light of the first wavelength and is configured to transmit or absorb light of the second wavelength.

[0030] The period of the plurality of nanostructures may be less than the first wavelength.

[0031] The top surfaces of the plurality of nanostructures and the top surface of the low-refractive-index layer can be disposed on the same plane, and the top surfaces of the plurality of nanostructures and the top surface of the low-refractive-index layer can directly contact the first electrode.

[0032] The top surface of the low refractive index layer can be disposed on the top surface of the plurality of nanostructures, the top surface of the plurality of nanostructures can be spaced apart from the first electrode, and the top surface of the low refractive index layer can directly contact the first electrode.

[0033] The reflective layer may further include a metal reflective film, which is flat and directly contacts the bottom surface of the plurality of nanostructures.

[0034] The low refractive index layer can be disposed on the top surface of the metal reflective film that does not contact the bottom surface of the plurality of nanostructures, and can also be disposed on the bottom surface of the metal reflective film.

[0035] The reflective layer may further include a metal reflective film, which is flat and disposed on the bottom surface of the low refractive index layer.

[0036] The second pixel may include: a reflective layer comprising a plurality of regularly arranged two-dimensional nanostructures and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; a first electrode disposed on the reflective layer; an organic emitting layer disposed on the first electrode and configured to emit visible light including light of the first wavelength and light of the second wavelength; and a second electrode disposed on the organic emitting layer, wherein each of the plurality of nanostructures of the reflective layer of the second pixel may include a non-metallic material, and the low-refractive-index layer of the reflective layer of the second pixel may include a dielectric material having a first refractive index lower than the second refractive index of the non-metallic material.

[0037] The diameter of each of the plurality of nanostructures of the second pixel, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures can be determined such that the reflective layer of the second pixel has the highest reflectivity for light of the second wavelength and is configured to transmit or absorb light of the first wavelength.

[0038] The height of each of the plurality of nanostructures in the reflective layer of the first pixel and the height of each of the plurality of nanostructures in the reflective layer of the second pixel can be the same, and the period of the plurality of nanostructures in the reflective layer of the first pixel and the period of the plurality of nanostructures in the reflective layer of the second pixel can be different from each other.

[0039] The first electrode, organic emission layer and second electrode of the first pixel can be the same as the first electrode, organic emission layer and second electrode of the second pixel, respectively.

[0040] According to another aspect of an example embodiment, a light-emitting device is provided, comprising: a reflective layer including a plurality of regularly arranged two-dimensional nanostructures and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; a first electrode disposed on the reflective layer; an organic emitting layer disposed on the first electrode; and a second electrode disposed on the organic emitting layer, wherein each of the plurality of nanostructures comprises a dielectric material or a semiconductor material, and the low-refractive-index layer comprises a dielectric material having a second refractive index lower than a first refractive index of the dielectric material or semiconductor material, wherein the reflective layer and the second electrode form a microcavity having a resonant wavelength, and wherein the diameter of each of the plurality of nanostructures of the reflective layer, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures are determined such that the reflective layer has the highest reflectivity for light with a wavelength corresponding to the resonant wavelength of the microcavity. Attached Figure Description

[0041] The above and / or other aspects, features, and advantages of exemplary embodiments of the present disclosure will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0042] Figure 1 This is a cross-sectional view showing the structure of a light-emitting device according to an example embodiment;

[0043] Figure 2 This illustrates an example embodiment. Figure 1 Detailed cross-sectional view of the structure of the organic emission layer;

[0044] Figure 3 This illustrates an embodiment according to another example. Figure 1 Detailed cross-sectional view of the structure of the organic emission layer;

[0045] Figure 4 It is shown Figure 1 A perspective view of the structure of the reflective layer;

[0046] Figure 5 and Figure 6 This illustrates an embodiment according to another example. Figure 1 A plan view of the arrangement of multiple nanostructures in the reflective layer;

[0047] Figure 7A , Figure 7B , Figure 7C and Figure 7D It is a graph showing the variation of the reflectivity of the reflective layer according to the thickness and period of each nanostructure;

[0048] Figure 8A , Figure 8B and Figure 8C This is a cross-sectional view showing a highly reflective layer with selective reflectivity for blue light, green light, and red light according to an example embodiment;

[0049] Figure 9 It is a graph showing the relationship between the reflectivity of the reflective layer and the wavelength for multiple nanostructures;

[0050] Figure 10 This is a cross-sectional view showing a structure used to simulate the characteristics of a light-emitting device based on the optical length of a microcavity;

[0051] Figure 11 It shows the basis Figure 10 The optical length of the microcavity and the simulated reflectance of blue, green and red light are plotted in graphs.

[0052] Figure 12 and Figure 13 It shows the basis Figure 10 The optical length of the microcavity, and the emission spectra of green and red light are plotted.

[0053] Figure 14A , Figure 14B and Figure 14C This is a cross-sectional view showing a reflective layer with high reflectivity selectively targeting blue light, green light, and red light, respectively, according to another example embodiment;

[0054] Figure 15 It is a graph showing the relationship between the period of multiple nanostructures and the reflectivity of the reflective layer for blue, green and red light;

[0055] Figure 16 It is a graph showing the relationship between the reflectivity of the reflective layer and the wavelength for multiple nanostructures;

[0056] Figure 17 , Figure 18 and Figure 19 It is a graph showing the emission spectra of blue, green and red light according to the optical length of the microcavity;

[0057] Figure 20 and Figure 21 This is a plan view illustrating the shape of multiple nanostructures of the reflective layer according to other example embodiments;

[0058] Figure 22 It is a graph showing the reflective properties of a reflective layer configured to reflect blue light according to the shape of the nanostructure;

[0059] Figure 23 It is a graph showing the reflection characteristics of a reflective layer configured to reflect green light according to the shape of the nanostructure;

[0060] Figure 24 It is a graph showing the reflection characteristics of a reflective layer configured to reflect red light according to the shape of the nanostructure;

[0061] Figure 25 This is a cross-sectional view showing the structure of a light-emitting device according to another example embodiment;

[0062] Figure 26 This is a cross-sectional view showing the structure of a light-emitting device according to another example embodiment;

[0063] Figure 27 This is a cross-sectional view showing the structure of a light-emitting device according to another example embodiment;

[0064] Figure 28 This is a cross-sectional view showing the structure of a light-emitting device according to another example embodiment;

[0065] Figure 29 This is a cross-sectional view showing the structure of a display device according to an example embodiment; and

[0066] Figure 30 This is a cross-sectional view showing the structure of a display device according to another example embodiment. Detailed Implementation

[0067] Reference will now be made in detail to the exemplary embodiments illustrated in the accompanying drawings, wherein similar reference numerals throughout the drawings denote similar elements. In this respect, the exemplary embodiments may take different forms and should not be construed as limited to the description set forth herein. Therefore, the exemplary embodiments are described below only with reference to the accompanying drawings to explain various aspects. As used herein, the term “and / or” includes any and all combinations of one or more of the relevant listed items. When a statement such as “at least one” follows a list of elements, it modifies the entire list of elements without modifying any individual element in the list. For example, the statement “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.

[0068] In the following, a light-emitting device and a display device including the light-emitting device will be described in detail with reference to the accompanying drawings. Similar reference numerals always denote similar elements, and the dimensions of elements may be enlarged in the drawings for clarity and ease of explanation. Furthermore, the exemplary embodiments described below are merely examples, and various modifications can be made from these exemplary embodiments.

[0069] When referring to an element as being "on" another element, the element may be directly on the other element, or there may be an intermediate element in between. The singular forms "a," "an," and "the" are intended to also include the plural forms, unless the context explicitly indicates otherwise. When a part "includes" an element, it may also include another element, rather than excluding the presence of other elements, unless otherwise described.

[0070] In the context of describing this disclosure, the terms “a,” “an,” and “the,” and similar pronouns, should be interpreted to cover both singular and plural cases. Unless otherwise indicated herein or explicitly stated otherwise by the context, the steps of all methods described herein may be performed in any suitable order, and are not limited to the order described.

[0071] Terms such as “unit” or “module” refer to a unit that performs at least one function or operation, and these units can be implemented as hardware or software or a combination of hardware and software.

[0072] Furthermore, the lines or components of the connecting elements shown in the accompanying drawings are merely examples of functional and / or physical or circuit connections. In actual devices, the connections between components can be represented by a variety of replaceable or additional functional, physical, or circuit connections.

[0073] Any and all examples or language used herein are intended only to better describe this disclosure and do not limit the scope of this disclosure, unless otherwise stated.

[0074] Figure 1 This is a cross-sectional view showing the structure of a light-emitting device according to an example embodiment. (Refer to...) Figure 1 The light-emitting device 100 according to an example embodiment may include: a reflective layer 110 including a plurality of nanostructures 112 arranged in two dimensions; a first electrode 121 disposed on the reflective layer 110; an organic emitting layer 130 disposed on the first electrode 121; and a second electrode 122 disposed on the organic emitting layer 130. The light-emitting device 100 may further include: a passivation layer 140, which is transparent and disposed opposite to the organic emitting layer 130 on the second electrode 122, and protects the second electrode 122.

[0075] The light-emitting device 100 can be an organic light-emitting diode (OLED). For example, Figure 2 This illustrates an example embodiment. Figure 1 A detailed cross-sectional view of the structure of the organic emitter layer 130. (Refer to...) Figure 2 The organic emitting layer 130 may include: a hole injection layer 132 disposed on the top surface of the first electrode 121; an organic emitting material layer 131 disposed on the top surface of the hole injection layer 132; and an electron injection layer 133 disposed on the top surface of the organic emitting material layer 131. In this structure, holes injected by the hole injection layer 132 and electrons injected by the electron injection layer 133 can combine with each other in the organic emitting material layer 131 to generate light. The wavelength of the generated light can be determined by the band gap of the luminescent material of the organic emitting material layer 131.

[0076] The organic emitting layer 130 may further include a hole transport layer 134 disposed between the hole injection layer 132 and the organic emitting material layer 131 to transport holes more smoothly. The organic emitting layer 130 may also include an electron transport layer 135 disposed between the electron injection layer 133 and the organic emitting material layer 131 to transport electrons more smoothly. The organic emitting layer 130 may include various additional layers as needed. For example, the organic emitting layer 130 may also include an electron blocking layer between the hole transport layer 134 and the organic emitting material layer 131, and may also include a hole blocking layer between the organic emitting material layer 131 and the electron transport layer 135.

[0077] The organic emitting material layer 131 can be configured to emit visible light. For example, the organic emitting material layer 131 can be configured to emit light in any of the following wavelengths: a wavelength corresponding to red light, a wavelength corresponding to green light, and a wavelength corresponding to blue light. However, the embodiments are not limited to this. For example, the organic emitting material layer 131 can be configured to emit white visible light including red, green, and blue light.

[0078] For example, Figure 3This illustrates an embodiment according to another example. Figure 1 A detailed cross-sectional view of the structure of the organic emitter layer 130. (Refer to...) Figure 3 The organic emitting material layer 131 may include: a first organic emitting material layer 131a emitting red light, a second organic emitting material layer 131b emitting green light, and a third organic emitting material layer 131c emitting blue light. Furthermore, an exciton blocking layer 136 may be disposed between the first organic emitting material layer 131a and the second organic emitting material layer 131b, and between the second organic emitting material layer 131b and the third organic emitting material layer 131c. In this case, the organic emitting layer 130 can emit white light. However, the structure of the white light emitting organic emitting layer 130 is not limited to this. Instead of including three organic emitting material layers, namely, the first to third organic emitting material layers 131a, 131b, and 131c, the organic emitting layer 130 may include two complementary organic emitting material layers.

[0079] The first electrode 121 disposed on the bottom surface of the organic emitting layer 130 can be used as an anode to provide holes. The second electrode 122 disposed on the top surface of the organic emitting layer 130 can be used as a cathode to provide electrons. For this purpose, the first electrode 121 can be formed of a material with a relatively high work function, and the second electrode 122 can be formed of a material with a relatively low work function.

[0080] Furthermore, the first electrode 121 can be a transparent electrode that transmits light (e.g., visible light). For example, the first electrode 121 can include a transparent conductive oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), or aluminum zinc oxide (AZO).

[0081] The second electrode 122 can be a semi-transmissive electrode that reflects a portion of the light and transmits the remainder. For this purpose, the second electrode 122 can comprise a very thin reflective metal. For example, the second electrode 122 can be formed of silver (Ag), aluminum (Al), gold (Au), nickel (Ni), or alloys thereof, or can have a two-layer structure comprising silver (Ag) and magnesium (Mg) or a two-layer structure comprising aluminum (Al) and lithium (Li). The total thickness of the second electrode 122 can range from about 10 nm to about 50 nm. Because the second electrode 122 is very thin, a portion of the light can pass through the reflective metal.

[0082] The reflective layer 110 can be configured to reflect light generated by the organic emitting layer 130 and transmitted through the first electrode 121. For example, the reflective layer 110 can be configured to selectively reflect only light of a specific wavelength band and transmit or absorb light of another wavelength band.

[0083] The reflective layer 110 and the second electrode 122 can constitute a microcavity. For example, the microcavity can be formed between the reflective layer 110 and the second electrode 122 of the light-emitting device 100. For example, light generated by the organic emitting layer 130 can reciprocate and resonate between the reflective layer 110 and the second electrode 122, and then light corresponding to the resonant wavelength of the microcavity can be emitted to the outside through the second electrode 122.

[0084] The resonant wavelength of the microcavity formed between the reflective layer 110 and the second electrode 122 can be determined by the optical length L of the microcavity. For example, when the resonant wavelength of the microcavity is λ, the optical length L of the microcavity can be nλ / 2, where n is a natural number. The optical length L of the microcavity can be determined by the sum of the optical thicknesses of the layers constituting the microcavity between the reflective layer 110 and the second electrode 122, the phase retardation of the second electrode 122, and the phase shift (e.g., phase retardation) of the reflective layer 110. Here, the optical thickness of the layers constituting the microcavity between the reflective layer 110 and the second electrode 122 is not a simple physical thickness, but a thickness that takes into account the refractive index of the materials constituting the microcavity. For example, the optical thickness of the layers constituting the microcavity can be the sum of the optical thickness of the first electrode 121 and the optical thickness of the organic emitting layer 130.

[0085] According to an example embodiment, the optical length L or resonant wavelength of the microcavity can be adjusted by changing only the phase shift of the reflective layer 110 while fixing the optical thickness of each layer constituting the microcavity and the phase delay of the second electrode 122. To adjust the wavelength selectivity and phase shift of the reflective layer 110, a phase modulation surface can be formed on the reflective surface of the reflective layer 110 that contacts the first electrode 121. The phase modulation surface can include very small nanoscale patterns. For example, the phase modulation surface of the reflective layer 110 can have a superstructure in which nanostructures with dimensions smaller than the wavelength of visible light are periodically arranged.

[0086] Reference Figure 1 The reflective layer 110 may include: a plurality of nanostructures 112 arranged in a regular periodic structure in two dimensions; and a low-refractive-index layer 111 surrounding the plurality of nanostructures 112. The low-refractive-index layer 111 may completely surround the bottom surface, side surface, and top surface of each nanostructure 112. The plurality of nanostructures 112 may be completely buried and sealed in the low-refractive-index layer 111. Therefore, the top surface of the plurality of nanostructures 112 may not contact the first electrode 121, and only the top surface of the low-refractive-index layer 111 may directly contact the first electrode 121. The plurality of nanostructures 112 included in the low-refractive-index layer 111 may be arranged horizontally on the same plane.

[0087] Each nanostructure 112 may include a nonmetallic material having a first refractive index, and the low refractive index layer 111 may include a dielectric material having a second refractive index lower than the first refractive index. For example, the nonmetallic material of each nanostructure 112 may include a dielectric material or a semiconductor material having a high refractive index and low absorbance in the visible light region. For example, the dielectric material may include at least one of titanium dioxide (TiO2), barium titanate (BaTiO3), chromium oxide (Cr2O3), hafnium dioxide (HfO2), and silicon nitride (SiNx), and the semiconductor material may include at least one of silicon (Si), zinc sulfide (ZnS), zinc selenide (ZnSe), gallium phosphide (GaP), indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), and aminolevulinase (AlAs2). Furthermore, the low-refractive-index layer 111 can be formed of a dielectric material with low refractive index and low absorptivity in the visible light band, such as silicon dioxide (SiO2) or siloxane spin-coated glass (SOG). Although both the nanostructure 112 and the low-refractive-index layer 111 comprise materials with low reflectivity, guided mode resonance is formed by periodically arranging multiple nanostructures 112 with dimensions smaller than the visible light wavelength, and thus, the reflective layer 110 can have high reflectivity for specific wavelengths of light.

[0088] For example, when each nanostructure 112 has a cylindrical shape, the wavelength of light reflected by the reflective layer 110 can be determined by the diameter W of each nanostructure 112, the thickness T of each nanostructure 112, and the spacing or period P of the multiple nanostructures 112. When each nanostructure 112 has a polygonal cylindrical shape, the wavelength of light reflected by the reflective layer 110 can be determined by the maximum width W of each nanostructure 112, the thickness T of each nanostructure 112, and the spacing or period P of the multiple nanostructures 112.

[0089] Specifically, when the thickness T of the nanostructure 112 is relatively small, the full width at half maximum (FWHM) of the reflection peak may be small, resulting in relatively low reflectivity at wavelengths other than a specific wavelength. Conversely, as the thickness T of the nanostructure 112 increases, the FWHM of the reflection peak increases. For example, the thickness T of the nanostructure 112 can range from about 20 nm to about 200 nm. Furthermore, when the thickness T of the nanostructure 112 is fixed, the reflectivity at a specific wavelength can be controlled by adjusting the diameter or width W of each nanostructure 112 or the spacing or period P of multiple nanostructures 112. For example, when the light-emitting device 100 is used in the visible light region, the diameter or width W of each nanostructure 112 can range from about 100 nm to about 250 nm, and the spacing or period P of multiple nanostructures 112 can range from about 200 nm to about 500 nm.

[0090] The phase delay of the light reflected by the reflective layer 110 can be determined by the diameter or width W of each nanostructure 112, the spacing or period P of the multiple nanostructures 112, and the thickness T of each nanostructure 112.

[0091] Therefore, the resonant wavelength of the microcavity can be determined by the diameter W of each nanostructure 112, the thickness T of each nanostructure 112, and the period P of the multiple nanostructures 112. For example, when the resonant wavelength of the microcavity is λ, the diameter W of each nanostructure 112, the thickness T of each nanostructure 112, and the period P of the multiple nanostructures 112 can be selected such that the optical length L of the microcavity satisfies nλ / 2, where n is a natural number. The diameter W of each nanostructure 112, the thickness T of each nanostructure 112, and the period P of the multiple nanostructures 112 can be selected such that the reflective layer 110 has the highest reflectivity for light with a wavelength corresponding to the resonant wavelength of the microcavity.

[0092] Therefore, the resonant wavelength of the microcavity 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 nanostructure 112, the thickness T of each nanostructure 112, and the period P of the multiple nanostructures 112 can be selected such that the resonant wavelength of the microcavity corresponds to the red band, and the reflective layer 110 has the highest reflectivity for red band light. In this way, the emission wavelength of the light-emitting device 100 can be determined simply by using the structure of the phase modulation surface of the reflective layer 110.

[0093] To prevent the microcavity from becoming polarization-dependent, multiple nanostructures 112 can be arranged regularly and periodically to have 4-fold symmetry. When the microcavity is polarization-dependent, only light with a specific polarization component can resonate, thereby reducing the luminous efficiency of the light-emitting device 100. For example, Figure 4 It is shown Figure 1 A perspective view of the structure of the reflective layer 110. (Refer to...) Figure 4 Each of these nanostructures 112, each with a cylindrical shape, can be arranged in a two-dimensional, regular square array. Although in Figure 4 The nanostructure 112 has a cylindrical shape, but the shape of the nanostructure 112 is not limited to this. For example, the nanostructure 112 may have an elliptical cylindrical shape, a polygonal cylindrical shape (e.g., a rectangular cylindrical shape, a pentagonal cylindrical shape, etc.) or a cross-shaped cylindrical shape.

[0094] Figure 5 and Figure 6 This illustrates an example embodiment. Figure 1 A plan view of the arrangement of multiple nanostructures 112 in the reflective layer 110. As long as the multiple nanostructures possess 4-fold symmetry, the multiple nanostructures 112 can have any arrangement other than a square array. For example, as... Figure 5 As shown, multiple nanostructures 112 can be arranged in a two-dimensional hexagonal array, or as... Figure 6 As shown, multiple nanostructures 112 can be arranged in a two-dimensional, body-centered square array.

[0095] Reference Figure 4 and Figure 5 Multiple nanostructures 112 are arranged in a regular two-dimensional array pattern. However, the embodiments are not limited to this, and when the multiple nanostructures 112 have 4-fold symmetry, the multiple nanostructures 112 can be arranged in any other array. For example, the multiple nanostructures 112 can be arranged irregularly. In another example embodiment, the arrangement of the multiple nanostructures 112 can be designed to differ from 4-fold symmetry, so that the light-emitting device 100 emits light with only a specific polarization component. For example, the multiple nanostructures 112 can be arranged in a one-dimensional array pattern.

[0096] The reflective properties of a reflective layer 110 comprising multiple nanostructures 112 formed of non-metallic materials will now be described.

[0097] Figures 7A to 7D This is a graph showing the variation of the reflectivity of the reflective layer 110 according to the thickness and period of each nanostructure 112, based on an exemplary embodiment. Each nanostructure 112 has a cylindrical shape and is formed of Si (silicon), and the low-refractive-index layer 111 is formed of SiO2. Figures 7A to 7D This is a graph showing the thickness T of each nanostructure 112 when it is 30 nm, 40 nm, 50 nm, and 120 nm. Figures 7A to 7D The shaded area in the graph indicates a case where the reflectivity of reflective layer 110 is equal to or greater than 80%.

[0098] like Figures 7A to 7D As shown in the graph, when the thickness of each nanostructure 112 is fixed, the wavelength band in which the reflectivity of the reflective layer 110 is equal to or greater than 80% can increase with the increase of the period of the multiple nanostructures 112. The period of the multiple nanostructures 112 is smaller than the wavelength in which the reflectivity of the reflective layer 110 is equal to or greater than 80%. Therefore, the period of the multiple nanostructures 112 can be selected to be smaller than the resonant wavelength of the microcavity.

[0099] As the thickness of each nanostructure 112 increases, the width of the band in which the reflective layer 110 has a reflectivity equal to or greater than 80% increases for the same period, indicating an increase in the full width at half maximum (FWHM) of the reflection peak. For example, the width of the band in which the reflectivity equal to or greater than 80% is greater when the thickness of each nanostructure 112 is 120 nm than when the thickness of each nanostructure 112 is 30 nm. As the FWHM of the reflection peak increases, the color purity of the light emitted by the light-emitting device 100 may decrease. Therefore, the reflective properties of the reflective layer 110 can vary depending on the materials of the nanostructures 112 and the low-refractive-index layer 111, but the thickness of each nanostructure 112 can be chosen to be equal to or less than 200 nm.

[0100] Figures 8A to 8C This is a cross-sectional view showing a highly reflective layer 110 with selective high reflectivity for blue, green, and red light, respectively, according to an exemplary embodiment. The nanostructure 112 has a cylindrical shape and is formed of Si, and the low-refractive-index layer 111 is formed of SiO2. Figures 8A to 8C In this study, the thickness of nanostructure 112 was fixed at 60 nm. Figure 8A The period of the multiple nanostructures 112 in the blue light reflective layer 110 can be 236 nm. Figure 8B The period of the multiple nanostructures 112 of the reflective layer 110 that reflects green light can be 337 nm, and Figure 8C The period of the multiple nanostructures 112 in the reflective layer 110 that reflects red light can be 412 nm. Figures 8A to 8C In this process, the diameter of each nanostructure 112 is chosen to be half of the period.

[0101] Figure 9 This is a graph showing the relationship between the reflectivity of the reflective layer 110 and wavelength for multiple nanostructures 112. (Refer to...) Figure 9 The curve graph, Figure 8A The reflective layer 110 has a maximum reflectivity of 61.5% for blue light with a wavelength of approximately 450 nm. Figure 8B The reflective layer 110 has a maximum reflectivity of 92.6% for green light with a wavelength of approximately 550 nm, and Figure 8CThe reflective layer 110 has a maximum reflectivity of 91.9% for red light with a wavelength of approximately 650 nm. Therefore, when using the reflective layer 110, which includes multiple nanostructures 112 formed of non-metallic materials, the emission wavelength of the light-emitting device 100 can be selected by increasing the reflectivity only for specific wavelengths in the visible light region.

[0102] A highly efficient top-emitting microcavity can be formed by filling an organic emission layer 130 between a reflective layer 110 comprising multiple nanostructures 112 formed of non-metallic material and a thin, flat second electrode 122. Figure 10 This is a cross-sectional view showing the structure used to simulate the characteristics of the light-emitting device 100 based on the optical length of the microcavity. Figure 10 In the structure, SiO2, the same material as the low-refractive-index layer 111 (instead of the organic emission layer), is filled between the reflective layer 110 and the second electrode 122. Figures 8A to 8C Each of the reflective layers is used as a reflective layer 110. Silver (Ag) with a thickness of 30 nm is used as the second electrode 122.

[0103] By emitting white light onto the second electrode 122 from the outside, measuring the spectrum of the reflected light, and changing the optical length L of the microcavity, the reflectivity of light corresponding to the resonant wavelength of the microcavity decreases because the light whose wavelength corresponds to the resonant wavelength of the microcavity is absorbed by SiO2 while resonating between the reflective layer 110 and the second electrode 122.

[0104] Figure 11 It shows the basis Figure 10 The graph shows the reflectance of blue, green, and red light for a microcavity with varying optical length L. As the optical length L of the microcavity changes, the reflectance of blue, green, and red light... Figure 10 The structure absorbs light at different wavelengths. As indicated by the dashed circle, there exists an optical length L of a microcavity for absorbing all blue, green, and red light. For example, all blue, green, and red light can be absorbed at an optical length corresponding to a common multiple of the optical lengths for absorbing blue light, green light, and red light.

[0105] With this in mind, when the optical length L of the microcavity of the light-emitting device 100 is appropriately selected, the emission color of the light-emitting device 100 can be determined solely by the dimensions of the nanostructure 112 of the reflective layer 110. Therefore, the physical thicknesses of the light-emitting devices for emitting blue light, green light, and red light can be set to be the same. For example, the light-emitting devices for emitting blue light, green light, and red light can be fabricated by fixing the optical length L of the microcavity and changing the dimensions of the nanostructure 112. The physical thicknesses of the fabricated light-emitting devices for emitting blue, green, and red light, respectively, can be set to be the same.

[0106] Figure 12 and Figure 13 It shows the basis Figure 10 The curves showing the optical length L of the microcavity and the emission spectra of green and red light are shown. Figure 12 and Figure 13 In the experiment, a white light source was disposed in SiO2 between the reflective layer 110 and the second electrode 122, and the intensity of the light emitted by the second electrode 122 was calculated.

[0107] Figure 12 It shows when Figure 8B The result when the reflective layer is used as reflective layer 110. (Refer to...) Figure 12 The graph shows that when the optical length L of the microcavity is 320 nm, the following resonance peak can be obtained, which amplifies the intensity of the light generated by the light source inside the microcavity by approximately 2.5 times. Furthermore, the full width at half maximum (FWHM) of this resonance peak is approximately 10 nm, which is very narrow. Figure 13 It shows when Figure 8C The result when the reflective layer is used as reflective layer 110. (Refer to...) Figure 13 The curve shows that when the optical length L of the microcavity is 380 nm, the following resonance peak can be obtained. This resonance peak is amplified by approximately 4.5 times the intensity of the light generated by the light source inside the microcavity, and the full width at half maximum (FWHM) of this resonance peak is approximately 7 nm, which is very narrow. Therefore, because almost no light with wavelengths other than the target wavelength is emitted, very high color purity can be obtained.

[0108] Although nanostructure 112 is Figures 8A to 13 The reflective layer 110 is formed from Si, but the nanostructure 112 can be formed from materials other than Si, and the properties of the reflective layer 110 can be changed accordingly. Figures 14A to 14C This is a cross-sectional view showing a reflective layer 110 with high reflectivity selectively targeting blue, green, and red light, respectively, according to another example embodiment. Each nanostructure 112 has a cylindrical shape and is formed of TiO2, and the low-refractive-index layer 111 is formed of SiO2. Figures 14A to 14CIn this design, the thickness of the nanostructure 112 is fixed at 60 nm. The period of the multiple nanostructures 112 is chosen to be smaller than the emission wavelength. For example, Figure 14A The period of the multiple nanostructures 112 in the reflective layer 110 that reflects blue light can be 291 nm. Figure 14B The period of the multiple nanostructures 112 of the reflective layer 110 that reflects green light can be 364 nm, and Figure 14C The period of the multiple nanostructures 112 in the reflective layer 110 that reflects red light can be 435 nm. Figures 14A to 14C In this process, the diameter of each nanostructure 112 is chosen to be half of the period.

[0109] Figure 15 This is a graph showing the relationship between the period of the plurality of nanostructures 112 and the reflectivity of the reflective layer 110 for blue, green, and red light. For blue light, approximately 99% reflectivity can be obtained when the period of the plurality of nanostructures 112 is 291 nm, and the reflectivity decreases rapidly as the period of the plurality of nanostructures 112 changes. For green light, approximately 99% reflectivity can be obtained when the period of the plurality of nanostructures 112 is 364 nm, and the reflectivity decreases rapidly as the period of the plurality of nanostructures 112 changes. For red light, approximately 99% reflectivity can be obtained when the period of the plurality of nanostructures 112 is 435 nm, and the reflectivity decreases rapidly as the period of the plurality of nanostructures 112 changes.

[0110] Figure 16 This is a graph showing the relationship between the reflectivity of the reflective layer 110 and wavelength for multiple nanostructures 112. (Refer to...) Figure 16 The curve graph, Figure 14A The reflective layer 110 has a maximum reflectivity of 99% for blue light with a wavelength of approximately 450 nm. Figure 14B The reflective layer 110 has a maximum reflectivity of 99% for green light with a wavelength of approximately 550 nm, and Figure 14C The reflective layer 110 has a maximum reflectivity of 99% for red light with a wavelength of approximately 650 nm. Figure 16 It was also shown that the crosstalk noise at wavelengths other than the target wavelength is less than about 20%, thus the wavelength selectivity of the reflective layer 110 is relatively good.

[0111] also, Figures 17 to 19 This is a graph showing the emission spectra of blue, green, and red light based on the optical length of the microcavity. Figures 17 to 19 It is by... Figures 14A to 14C The reflective layer 110 is applied to Figure 10 It is obtained through the structure. Figures 17 to 19In the experiment, a white light source was disposed in SiO2 between the reflective layer 110 and the second electrode 122, and the intensity of the light emitted by the second electrode 122 was calculated.

[0112] Figure 17 It shows when Figure 14A The result when the reflective layer is used as reflective layer 110. (Refer to...) Figure 17 The curve shows that when the optical length L of the microcavity is 240 nm, the following resonance peak can be obtained, which is amplified by about 3.5 times the intensity of the light generated by the light source inside the microcavity. Figure 18 It shows when Figure 14B The result when the reflective layer is used as reflective layer 110. (Refer to...) Figure 18 The curve shows that when the optical length L of the microcavity ranges from about 300 nm to about 320 nm, the following resonance peak can be obtained, which is amplified by about 4.2 times the intensity of the light generated by the light source inside the microcavity. Figure 19 It shows when Figure 14C The result when the reflective layer is used as reflective layer 110. (Refer to...) Figure 19 The curve shows that when the optical length L of the microcavity is 380 nm, the following resonance peak can be obtained, which is amplified by approximately 4.5 times the intensity of the light generated by the light source inside the microcavity. Furthermore, Figures 17 to 19 The full width at half maximum (FWHM) of each resonance peak in the curve is approximately 3 nm, which is very narrow, thus significantly reducing crosstalk noise. Therefore, because almost no light with wavelengths other than the target wavelength is emitted, very high color purity can be obtained.

[0113] Although each nanostructure 112 is in Figures 8A to 19 While it has a cylindrical shape, the nanostructure 112 can have any of a variety of other shapes. For example, Figure 20 and Figure 21 This is a plan view illustrating the shapes of multiple nanostructures of the reflective layer according to other example embodiments. (e.g.) Figure 20 As shown, each nanostructure 112 can have a rectangular column shape, or as... Figure 21 As shown, each nanostructure 112 can have a cross-shaped columnar shape. However, the embodiments are not limited to this. For example, each nanostructure 112 can have an elliptical columnar shape or a polygonal columnar shape (e.g., a pentagonal columnar shape), etc. The reflective properties of the reflective layer 110 can vary depending on the shape of the nanostructure 112.

[0114] For example, Figure 22 It is a graph showing the reflection characteristics of the reflective layer 110 configured to reflect blue light according to the shape of the nanostructure 112. Figure 23 It is a graph showing the reflection characteristics of the reflective layer 110 configured to reflect green light according to the shape of the nanostructure 112. Figure 24 It is a graph showing the reflection characteristics of the reflective layer 110 configured to reflect red light according to the shape of the nanostructure 112.

[0115] Each nanostructure 112 is formed of Si, and the low-refractive-index layer 111 is formed of SiO2. Figures 22 to 24 In each of the examples, solid lines indicate that the nanostructure 112 has a cylindrical shape, dashed lines indicate that the nanostructure 112 has a cross-shaped columnar shape, and dotted lines indicate that the nanostructure 112 has a square columnar shape. In all examples, the thickness of the nanostructure 112 is fixed at 100 nm. In the reflective layer 110 for reflecting blue light, the width of the nanostructure 112 is 150 nm and the period of the multiple nanostructures 112 is 290 nm. In the reflective layer 110 for reflecting green light, the width of the nanostructure 112 is 180 nm and the period of the multiple nanostructures 112 is 330 nm. In the reflective layer 110 for reflecting red light, the width of the nanostructure 112 is 180 nm and the period of the multiple nanostructures 112 is 410 nm.

[0116] Reference Figures 22 to 24 When the nanostructure 112 has a cylindrical shape, the reflection peaks are formed at 450 nm, 550 nm, and 650 nm. When the nanostructure 112 has a cross-shaped columnar shape, the reflection peaks are formed at wavelengths slightly shorter than 450 nm, 550 nm, and 650 nm. When the nanostructure 112 has a square columnar shape, the reflection peaks are formed at wavelengths slightly longer than 450 nm, 550 nm, and 650 nm. In the reflective layer 110 used for reflecting blue and green light, the reflectivity of each of the nanostructures 112 with cross-shaped and square columnar shapes is greater than the reflectivity of the nanostructure 112 with a cylindrical shape. In the reflective layer 110 used for reflecting red light, the reflectivity of the nanostructure with a square columnar shape is similar to that of the nanostructure 112 with a cylindrical shape. Therefore, even when the nanostructure 112 has a shape other than a cylindrical shape, a reflective layer 110 with selective high reflectivity can be designed, and the desired wavelength of the reflected light can be controlled by changing the size of the nanostructure 112.

[0117] Figure 25 This is a cross-sectional view illustrating the structure of a light-emitting device according to another example embodiment. Figure 1 In the light-emitting device 100, a low-refractive-index layer 111 completely covers the top surface of the nanostructure 112. However, in Figure 25In the light-emitting device 100a, the low-refractive-index layer 111 does not cover the top surface of the nanostructure 112, and the top surfaces of the multiple nanostructures 112 and the top surface of the low-refractive-index layer 111 are disposed on the same plane. The top surfaces of the multiple nanostructures 112 and the top surface of the low-refractive-index layer 111 can directly contact the first electrode 121. The side surfaces and bottom surfaces of the multiple nanostructures 112 can be completely surrounded and sealed by the low-refractive-index layer 111.

[0118] Figure 26 This is a cross-sectional view illustrating the structure of a light-emitting device according to another example embodiment. (Refer to...) Figure 26 The reflective layer 110 of the light-emitting device 100b may further include a flat, highly reflective metal reflective film 113. For example, the metal reflective film 113 may include silver (Ag), aluminum (Al), gold (Au), nickel (Ni), or a combination thereof. The metal reflective film 113 may directly contact the bottom surface of the nanostructure 112. A low-refractive-index layer 111 may surround the bottom surface of the metal reflective film 113 and the top surface of the metal reflective film 113 that does not contact the nanostructure 112.

[0119] Figure 27 This is a cross-sectional view showing the structure of a light-emitting device according to another example embodiment. Although the metal reflective film 113 is in... Figure 26 The bottom surface of the nanostructure 112 is in direct contact with the surface, but the embodiments are not limited to this. Figure 27 In the light-emitting device 100c, a metal reflective film 113 can be disposed on the bottom surface of the low refractive index layer 111. In this case, the metal reflective film 113 does not directly contact the nanostructure 112.

[0120] Figure 28 This is a cross-sectional view illustrating the structure of a light-emitting device according to another example embodiment. (Refer to...) Figure 28 The light-emitting device 100d may also include a substrate 101. Examples of substrate 101 may include a semiconductor substrate, such as a silicon (Si) substrate, a transparent glass substrate, and a transparent polymer substrate. The reflective layer 110, the first electrode 121, the organic emitting layer 130, the second electrode 122, and the passivation layer 140 may be sequentially stacked on the substrate 101.

[0121] Furthermore, the low-refractive-index layer 111 can be formed of two different dielectric materials. For example, the low-refractive-index layer 111 may include: a first low-refractive-index layer 111a disposed below the nanostructure 112; and a second low-refractive-index layer 111b disposed covering the side and top surfaces of the nanostructure 112. The first low-refractive-index layer 111a and the second low-refractive-index layer 111b may have different refractive indices and may both be formed of a transparent dielectric material having a refractive index lower than that of the nanostructure 112. The wavelength of the reflected light reflected by the reflective layer 110 can be controlled by the first low-refractive-index layer 111a and the second low-refractive-index layer 111b.

[0122] As described above, by using a reflective layer 110 comprising a plurality of nanostructures 112 formed of a non-metallic material, blue, green, and red light with high efficiency and narrow full width at half maximum (FWHM) can be emitted according to the optical length L of the microcavity. By fixing the height of the nanostructures 112 of the reflective layer 110 and the optical length L of the microcavity while only changing the width and / or period of the nanostructures 112, the emission wavelength of the light-emitting device 100 can be more easily determined. Therefore, when the light-emitting device 100 according to the exemplary embodiment is applied to the red, green, and blue (RGB) sub-pixels of a display device, the process of manufacturing the display device can be facilitated.

[0123] For example, Figure 29 This is a cross-sectional view showing the structure of a display device according to an example embodiment. (Refer to...) Figure 29 The display device 200 according to an example embodiment may include a display substrate 201 and a first pixel 100B, a second pixel 100G, and a third pixel 100R aligned on the display substrate 201. Figure 29 In the middle, although each of the first to third pixels 100B, 100G and 100R has the same as Figure 1 The light-emitting device 100 has the same structure as the first pixel to the third pixel 100B, 100G and 100R, but each of them can have the following structure: Figures 25 to 28 The structure of any one of the light-emitting devices 100a, 100b, 100c, and 100d. Furthermore, although for ease of explanation... Figure 29 Only one first pixel 100B, one second pixel 100G, and one third pixel 100R are shown, but a large number of first to third pixels 100B, 100G, and 100R can be arranged repeatedly.

[0124] The first to third pixels 100B, 100G, and 100R may include: reflective layers 110B, 110G, and 110R, each comprising a plurality of two-dimensionally arranged nanostructures 112B, 112G, and 112R; a first electrode 121 disposed on the reflective layers 110B, 110G, and 110R; an organic emitting layer 130 disposed on the first electrode 121; and a second electrode 122 disposed on the organic emitting layer 130. Furthermore, the first to third pixels 100B, 100G, and 100R may also each include: a passivation layer 140, which is transparent and disposed on the second electrode 122 to protect the second electrode 122.

[0125] The first to third pixels 100B, 100G, and 100R can be configured to emit light with different wavelengths. For example, the first pixel 100B can be configured to emit blue light B, the second pixel 100G can be configured to emit green light G, and the third pixel 100R can be configured to emit red light R. For this purpose, the reflective layers 110B, 110G, and 110R of the first to third pixels 100B, 100G, and 100R can each include nanostructures 112B, 112G, and 112R with different dimensions 6.

[0126] For example, the diameter of each nanostructure 112B, the height of each nanostructure 112B, and the period of multiple nanostructures 112B can be determined such that the reflective layer 110B of the first pixel 100B has the highest reflectivity for blue light B and transmits or absorbs light R and G in other wavelengths. Similarly, the diameter of each nanostructure 112G, the height of each nanostructure 112G, and the period of multiple nanostructures 112G can be determined such that the reflective layer 110G of the second pixel 100G has the highest reflectivity for green light G and transmits or absorbs light B and R in other wavelengths. Likewise, the diameter of each nanostructure 112R, the height of each nanostructure 112R, and the period of multiple nanostructures 112R can be determined such that the reflective layer 110R of the third pixel 100R has the highest reflectivity for red light R and transmits or absorbs light B and G in other wavelengths.

[0127] Specifically, the first to third pixels 100B, 100G, and 100R can be configured such that the heights of the multiple nanostructures 112B, 112G, and 112R are fixed to the same value, and the diameters and periods of the multiple nanostructures 112B, 112G, and 112R are different from each other. For example, the period of the nanostructure 112B of the first pixel 100B can be less than the blue wavelength, and can be less than the period of the nanostructure 112G of the second pixel 100G. The period of the nanostructure 112G of the second pixel 100G can be less than the green wavelength, and can be less than the period of the nanostructure 112R of the third pixel 100R. Furthermore, the period of the nanostructure 112R of the third pixel 100R can be less than the red wavelength.

[0128] The optical lengths of the microcavities in the first to third pixels of 100B, 100G, and 100R can be the same. (See reference...) Figure 10 and Figure 11 As described, the optical lengths of the microcavities of the first to third pixels 100B, 100G, and 100R can correspond to a common multiple of the optical lengths used to resonate blue light, green light, and red light. Therefore, the emission wavelengths of the first to third pixels 100B, 100G, and 100R are determined solely by the dimensions of the nanostructures 112B, 112G, and 112R of the reflective layers 110B, 110G, and 110R. In the first to third pixels 100B, 100G, and 100R, components other than the reflective layers 110B, 110G, and 110R, such as the first electrode 121, the organic emitting layer 130, and the second electrode 122, can have the same composition and the same thickness. Therefore, the physical thicknesses of the first to third pixels 100B, 100G, and 100R can be the same. Therefore, the process of manufacturing the display device 200 can be simplified, and the manufacturing cost can be reduced.

[0129] Figure 30 This is a cross-sectional view illustrating the structure of a display device according to another example embodiment. Figure 30 In the display device 300, the reflective layers 110G and 110R of the second pixel 100G and the third pixel 100R may respectively include nanostructures 112G and 112R, but the reflective layer 110B of the first pixel 100B may not include nanostructures. Figure 30 Each of the reflective layers 110B, 110G, and 110R of the display device 300 may further include a metal reflective film 113. The metal reflective film 113 can directly contact the bottom surface of each of the nanostructures 112G and 112R. However, as... Figure 27As shown, the metal reflective film 113 can contact the bottom surface of the low refractive index layer 111. The metal reflective films 113 of reflective layers 110B, 110G and 110R can be disposed on the same plane.

[0130] The optical length of the microcavity of the first pixel 100B can be determined such that the resonant wavelength matches the blue wavelength. For example, the optical length of the microcavity of the first pixel 100B can be determined by the sum of the optical lengths of the materials disposed between the metal reflective film 113 and the second electrode 122. Therefore, the first pixel 100B can emit light B in the blue band.

[0131] In the second pixel 100G and the third pixel 100R, the resonant wavelength of the microcavity can be adjusted by using nanostructures 112G and 112R, via phase delay of the reflected light. For example, the nanostructure 112G of the second pixel 100G can be configured such that the resonant wavelength of the microcavity of the second pixel 100G matches the green wavelength to delay the phase of the reflected light and has the highest reflectivity for light G in the green band. The nanostructure 112R of the third pixel 100R can be configured such that the resonant wavelength of the microcavity of the third pixel 100R matches the red wavelength to delay the phase of the reflected light and has the highest reflectivity for light R in the red band.

[0132] It should be understood that the exemplary embodiments described herein should be considered only in a descriptive sense and not for limiting purposes. The description of features or aspects in each exemplary embodiment should typically be regarded as other similar features or aspects that can be used in other embodiments. Although exemplary embodiments have been described with reference to the accompanying drawings, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A light-emitting device, comprising: The reflective layer comprises a plurality of regularly arranged two-dimensional nanostructures and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; The first electrode is disposed on the reflective layer; An organic emission layer is disposed on the first electrode; as well as The second electrode is disposed on the organic emission layer. Each of the plurality of nanostructures comprises a non-metallic material, and the low-refractive-index layer comprises a dielectric material having a second refractive index lower than that of the non-metallic material. The low-refractive-index layer is configured to completely surround the bottom, side, and top surfaces of each of the plurality of nanostructures. The reflective layer further includes a metal reflective film, which is flat and directly contacts the bottom surface of the plurality of nanostructures. The low-refractive-index layer surrounds the bottom surface of the metal reflective film and the top surface of the metal reflective film that does not contact the bottom surface of the plurality of nanostructures.

2. The light-emitting 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 the light and transmit the remainder of the light.

3. The light-emitting device according to claim 1, wherein, The non-metallic materials include dielectric materials or semiconductor materials.

4. The light-emitting device according to claim 3, wherein, The dielectric material includes at least one of TiO2, BaTiO3, Cr2O3, HfO2, and SiNx.

5. The light-emitting device according to claim 3, wherein, The semiconductor material includes at least one of Si, ZnS, ZnSe, GaP, InP, GaAs, GaN, and AlAs2.

6. The light-emitting device according to claim 1, wherein, The reflective layer and the second electrode form a microcavity with a resonant wavelength.

7. The light-emitting device according to claim 6, wherein, The diameter of each of the plurality of nanostructures in the reflective layer, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures are determined such that the reflective layer has the highest reflectivity for light with a wavelength corresponding to the resonant wavelength of the microcavity.

8. The light-emitting device according to claim 7, wherein, The period of the plurality of nanostructures is smaller than the resonant wavelength of the microcavity.

9. The light-emitting device according to claim 8, wherein, The periods of the multiple nanostructures range from 200 nm to 500 nm.

10. The light-emitting device according to claim 7, wherein, The height of each of the plurality of nanostructures ranges from 20 nm to 200 nm.

11. The light-emitting device according to claim 1, wherein, The top surfaces of the plurality of nanostructures are spaced apart from the first electrode, and the top surface of the low refractive index layer is in direct contact with the first electrode.

12. The light-emitting device according to claim 1, wherein, The low-refractive-index layer includes: a first low-refractive-index layer disposed on the bottom surface of the plurality of nanostructures, and a second low-refractive-index layer disposed on the side and top surfaces of the plurality of nanostructures. The first low-refractive-index layer and the second low-refractive-index layer comprise dielectric materials with different refractive indices.

13. A display device, comprising: The first pixel is configured to emit light of a first wavelength; as well as The second pixel is configured to emit light of a second wavelength that is different from the first wavelength. Wherein, the first pixel includes: The reflective layer comprises a plurality of regularly arranged two-dimensional nanostructures and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; The first electrode is disposed on the reflective layer; An organic emitting layer, disposed on the first electrode and configured to emit visible light including light of the first wavelength and light of the second wavelength; and The second electrode is disposed on the organic emission layer. Each of the plurality of nanostructures comprises a non-metallic material, and the low-refractive-index layer comprises a dielectric material having a second refractive index lower than that of the non-metallic material. The low-refractive-index layer is configured to completely surround the bottom, side, and top surfaces of each of the plurality of nanostructures. The reflective layer further includes a metal reflective film, which is flat and directly contacts the bottom surface of the plurality of nanostructures. The low-refractive-index layer surrounds the bottom surface of the metal reflective film and the top surface of the metal reflective film that does not contact the bottom surface of the plurality of nanostructures.

14. The display device according to claim 13, wherein, 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 remainder of the light.

15. The display device according to claim 13, wherein, The non-metallic materials include dielectric materials or semiconductor materials.

16. The display device according to claim 15, wherein, The dielectric material includes at least one of TiO2, BaTiO3, Cr2O3, HfO2, and SiNx.

17. The display device according to claim 15, wherein, The semiconductor material includes at least one of Si, ZnS, ZnSe, GaP, InP, GaAs, GaN, and AlAs2.

18. The display device according to claim 13, wherein, The diameter of each of the plurality of nanostructures in the reflective layer, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures are determined such that the reflective layer of the first pixel has the highest reflectivity for light of the first wavelength and is configured to transmit or absorb light of the second wavelength.

19. The display device according to claim 18, wherein, The period of the plurality of nanostructures is less than the first wavelength.

20. The display device according to claim 13, wherein, The top surfaces of the plurality of nanostructures are spaced apart from the first electrode, and the top surface of the low refractive index layer is in direct contact with the first electrode.

21. The display device according to claim 13, wherein, The second pixel includes: The reflective layer comprises a plurality of regularly arranged two-dimensional nanostructures and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; The first electrode is disposed on the reflective layer; An organic emitting layer, disposed on the first electrode and configured to emit visible light including light of the first wavelength and light of the second wavelength; and The second electrode is disposed on the organic emission layer. Each of the plurality of nanostructures in the reflective layer of the second pixel comprises a non-metallic material, and the low refractive index layer of the reflective layer of the second pixel comprises a dielectric material having a first refractive index lower than the second refractive index of the non-metallic material.

22. The display device according to claim 21, wherein, The diameter of each of the plurality of nanostructures of the second pixel, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures are determined such that the reflective layer of the second pixel has the highest reflectivity for light of the second wavelength and is configured to transmit or absorb light of the first wavelength.

23. The display device according to claim 21, wherein, The height of each of the plurality of nanostructures in the reflective layer of the first pixel is the same as the height of each of the plurality of nanostructures in the reflective layer of the second pixel, and the periods of the plurality of nanostructures in the reflective layer of the first pixel and the periods of the plurality of nanostructures in the reflective layer of the second pixel are different from each other.

24. The display device according to claim 21, wherein, The first electrode, organic emission layer and second electrode of the first pixel are the same as the first electrode, organic emission layer and second electrode of the second pixel.

25. A light-emitting device, comprising: The reflective layer comprises a plurality of regularly arranged two-dimensional nanostructures and a low-refractive-index layer disposed adjacent to the plurality of nanostructures; The first electrode is disposed on the reflective layer; An organic emission layer is disposed on the first electrode; as well as The second electrode is disposed on the organic emission layer. Each of the plurality of nanostructures comprises a dielectric material or a semiconductor material, and the low refractive index layer comprises a dielectric material having a second refractive index lower than that of the dielectric material or semiconductor material. The low-refractive-index layer is configured to completely surround the bottom, side, and top surfaces of each of the plurality of nanostructures. The reflective layer further includes a metal reflective film, which is flat and directly contacts the bottom surface of the plurality of nanostructures. The low-refractive-index layer surrounds the bottom surface of the metal reflective film and the top surface of the metal reflective film that does not contact the bottom surface of the plurality of nanostructures. The reflective layer and the second electrode form a microcavity with a resonant wavelength, and The diameter of each of the plurality of nanostructures in the reflective layer, the height of each of the plurality of nanostructures, and the period of the plurality of nanostructures are determined such that the reflective layer has the highest reflectivity for light with a wavelength corresponding to the resonant wavelength of the microcavity.

Images