Light emitting device and display apparatus including the same

Abstract

A light-emitting device and a display device with high luminous efficiency are provided. The light-emitting device includes: a first organic light-emitting material layer that generates light having a first wavelength; a second organic light-emitting material layer that generates light having a second wavelength different from the first wavelength; and a third organic light-emitting material layer that generates light having a third wavelength different from the first and second wavelengths. The first organic light-emitting material layer may be located at a position including a first antinode having a resonant wavelength that resonates in a microcavity, and the second and third organic light-emitting material layers may be located at a position including a second antinode having a resonant wavelength that resonates in a microcavity.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0155431, filed with the Korean Intellectual Property Office on November 19, 2020, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to a light-emitting device and a display device including the light-emitting device, and more specifically, to an organic light-emitting device (OLED) with improved luminous efficiency and an organic light-emitting display device. Background Technology

[0004] Organic light-emitting devices (OLEDs) are display devices that form images by emitting light based on the combination of holes supplied from the anode in an organic emitting layer and electrons supplied from the cathode. OLEDs have excellent display characteristics, such as wide viewing angle, fast response speed, small thickness, low manufacturing cost, and high contrast.

[0005] Furthermore, OLEDs can emit desired colors by selecting appropriate materials as the organic emitting layer. Based on this principle, color display devices can be manufactured using OLEDs. Summary of the Invention

[0006] One or more example embodiments provide an organic light-emitting device (OLED) with improved luminous efficiency and an organic light-emitting display device.

[0007] Additional aspects will be set forth in part in the description which follows, and will also be apparent in part from the description, or may be learned by practicing the embodiments presented in this disclosure.

[0008] According to one aspect of the embodiments, a light-emitting device includes: a reflective layer comprising a plurality of nanostructures; a first electrode disposed on the reflective layer; an organic light-emitting layer disposed on the first electrode; and a second electrode disposed on the organic light-emitting layer, wherein the reflective layer and the second electrode can form a microcavity having a resonant wavelength, wherein the organic light-emitting layer can include: a first organic light-emitting material layer configured to generate first light having a first wavelength; a second organic light-emitting material layer configured to generate second light having a second wavelength different from the first wavelength; and a third organic light-emitting material layer configured to generate third light having a third wavelength different from the first wavelength and the second wavelength, wherein the first organic light-emitting material layer can be disposed at a position of a first antinode of the resonant wavelength resonating in the microcavity, and wherein the second organic light-emitting material layer and the third organic light-emitting material layer can be disposed at a position of a second antinode of the resonant wavelength resonating in the microcavity.

[0009] The second and third organic light-emitting material layers can be adjacent to each other or mixed so that energy can be transferred from the second light-emitting dopant material in the second organic light-emitting material layer to the third light-emitting dopant material in the third organic light-emitting material layer.

[0010] The second organic light-emitting material layer can be spaced apart from the first organic light-emitting material layer between the first organic light-emitting material layer and the third organic light-emitting material layer, and can be arranged to be in direct contact with the third organic light-emitting material layer.

[0011] The organic light-emitting layer may further include: a hole injection layer located between the first electrode and the third organic light-emitting material layer; a charge generation layer located between the first organic light-emitting material layer and the second organic light-emitting material layer; and an electron injection layer located between the first organic light-emitting material layer and the second electrode.

[0012] The second luminescent dopant material in the second organic luminescent material layer and the third luminescent dopant material in the third organic luminescent material layer can be phosphorescent dopant materials, and the first luminescent dopant material in the first organic luminescent material layer is a fluorescent dopant material.

[0013] The organic light-emitting layer may also include a mixed layer of the second and third organic light-emitting material layers between the second and third organic light-emitting material layers.

[0014] The third organic light-emitting material layer can be partially mixed with the second organic light-emitting material layer to form a mixed layer, and the mixed layer is located below the second organic light-emitting material layer.

[0015] The organic light-emitting layer may also include a plurality of second organic light-emitting material layers and a plurality of third organic light-emitting material layers, which are arranged alternately in a direction from the second electrode toward the first electrode.

[0016] The thickness of each of the second organic light-emitting material layers can be greater than the thickness of each of the third organic light-emitting material layers.

[0017] The concentration of the second luminescent dopant material in the second organic luminescent material layer can be higher than the concentration of the third luminescent dopant material in the third organic luminescent material layer.

[0018] The organic light-emitting layer may also include an additional first organic light-emitting material layer disposed at the position of the third antinode of the resonant wavelength.

[0019] The organic light-emitting layer may also include a charge-generating layer disposed between an additional first organic light-emitting material layer and a third organic light-emitting material layer.

[0020] The width, height, and period of each of the multiple nanostructures in the reflective layer can be set so that the resonant wavelength of the microcavity is consistent with the second or third wavelength.

[0021] The period of multiple nanostructures can be smaller than the resonant wavelength of the microcavity.

[0022] The first electrode can be a transparent electrode, and the second electrode can be a semi-transparent electrode that reflects a portion of the light and transmits the remaining light.

[0023] According to one aspect of another embodiment, a display device is provided, comprising: a first pixel configured to emit first light of a first wavelength; a second pixel configured to emit second light of a second wavelength different from the first wavelength; and a third pixel configured to emit third light of a third wavelength different from the first and second wavelengths, wherein at least one of the first pixel, the second pixel, and the third pixel may include: a reflective layer including a plurality of nanostructures; a first electrode disposed on the reflective layer; an organic light-emitting layer disposed on the first electrode; and a second electrode disposed on the organic light-emitting layer. When at least one of the first pixel, the second pixel, and the third pixel includes a second pixel, the reflective layer and the second electrode included in the second pixel may constitute a microcavity for resonating the second light of the second wavelength. The organic light-emitting layer may include: a first organic light-emitting material layer configured to generate first light having a first wavelength; a second organic light-emitting material layer configured to generate second light having a second wavelength; and a third organic light-emitting material layer configured to generate third light having a third wavelength. The first organic light-emitting material layer may be disposed at a position of a first antinode of the resonant wavelength in the microcavity. The second and third organic light-emitting material layers may be disposed at positions of a second antinode of the resonant wavelength.

[0024] The second and third organic light-emitting material layers can be adjacent to each other or mixed so that energy can be transferred from the second light-emitting dopant material in the second organic light-emitting material layer to the third light-emitting dopant material in the third organic light-emitting material layer.

[0025] The second organic light-emitting material layer can be spaced apart from the first organic light-emitting material layer between the first organic light-emitting material layer and the third organic light-emitting material layer, and can be arranged to be in direct contact with the third organic light-emitting material layer.

[0026] The organic light-emitting layer may further include: a hole injection layer disposed between the first electrode and the third organic light-emitting material layer; a charge generation layer disposed between the first organic light-emitting material layer and the second organic light-emitting material layer; and an electron injection layer disposed between the first organic light-emitting material layer and the second electrode.

[0027] The second luminescent dopant material in the second organic luminescent material layer and the third luminescent dopant material in the third organic luminescent material layer can be phosphorescent dopant materials, and the first luminescent dopant material in the first organic luminescent material layer can be fluorescent dopant materials.

[0028] The organic light-emitting layer may also include a mixed layer of the second and third organic light-emitting material layers between the second and third organic light-emitting material layers.

[0029] The third organic light-emitting material layer can be mixed with the second organic light-emitting material layer to form a mixed layer, and the mixed layer can be disposed below the second organic light-emitting material layer.

[0030] The organic light-emitting layer may include a plurality of second organic light-emitting material layers and a plurality of third organic light-emitting material layers, which are arranged alternately in a direction from the second electrode toward the first electrode.

[0031] The thickness of each of the second organic light-emitting material layers can be greater than the thickness of each of the third organic light-emitting material layers.

[0032] The concentration of the second luminescent dopant material in the second organic luminescent material layer can be higher than the concentration of the third luminescent dopant material in the third organic luminescent material layer.

[0033] The display device may also include an additional first organic light-emitting material layer disposed at the position of the third antinode of the resonant wavelength.

[0034] The organic light-emitting layer may also include a charge-generating layer disposed between an additional first organic light-emitting material layer and a third organic light-emitting material layer.

[0035] The width, height, and period of each of the multiple nanostructures in the reflective layer can be set so that the microcavity resonates with the second wavelength of light.

[0036] At least one of the first pixel, the second pixel, and the third pixel may include the third pixel. The reflective layer and the second electrode included in the third pixel may constitute a third microcavity that resonates with a third wavelength of light.

[0037] At least one of the first pixel, the second pixel, and the third pixel may include the first pixel, and the reflective layer and the second electrode included in the first pixel may form a first microcavity that resonates with the first light of the first wavelength.

[0038] The physical thickness of the first pixel, the physical thickness of the second pixel, and the physical thickness of the third pixel can be equal to each other.

[0039] According to one aspect of another embodiment, a display device is provided, the display device including a plurality of pixels, wherein at least one of the plurality of pixels may include: an organic light-emitting layer disposed between a first electrode and a second electrode, and comprising: a first organic light-emitting material layer including a first light-emitting dopant material, but excluding a second light-emitting dopant material and a third light-emitting dopant material; a second organic light-emitting material layer including a second light-emitting dopant material, but excluding the first light-emitting dopant material and the third light-emitting dopant material; a third organic light-emitting material layer including a third light-emitting dopant material, but excluding the first light-emitting dopant material and the second light-emitting dopant material; a mixing layer formed by mixing the second light-emitting dopant material and the third light-emitting dopant material when the second organic light-emitting material layer and the third organic light-emitting material layer are in direct contact, and disposed between the second organic light-emitting material layer and the third organic light-emitting material layer; and a reflective layer including a plurality of nanostructures, and the first electrode, the organic light-emitting layer and the second electrode are disposed on the reflective layer. Attached Figure Description

[0040] The above and / or other solutions will become clearer by describing certain exemplary embodiments with reference to the accompanying drawings, in which:

[0041] Figure 1 This is a schematic cross-sectional view illustrating the structure of a light-emitting device according to an example embodiment;

[0042] Figure 2 It is shown schematically. Figure 1 A three-dimensional diagram of an example structure of the reflective layer shown;

[0043] Figure 3 It is shown schematically. Figure 1 A perspective view of another example structure of the reflective layer shown;

[0044] Figure 4 This is a cross-sectional view showing the structure of the organic light-emitting layer according to an example embodiment;

[0045] Figure 5 This is a table showing how the luminescent properties of the organic light-emitting material layer vary depending on its position within the organic light-emitting layer;

[0046] Figure 6 This is a cross-sectional view showing the structure of an organic light-emitting layer according to another example embodiment;

[0047] Figure 7A and Figure 7B This is a conceptual diagram illustrating energy transfer between different types of luminescent dopant materials;

[0048] Figure 8It is a graph showing how the light-emitting characteristics vary depending on the various arrangements between different types of organic light-emitting material layers;

[0049] Figure 9 This is a table showing how luminous efficiency varies depending on the various arrangements between different types of organic light-emitting material layers;

[0050] Figure 10 It is a graph showing how the luminous efficiency varies depending on the arrangement of different types of organic light-emitting material layers;

[0051] Figure 11 It is a graph showing the relationship between energy transfer rate and luminous efficiency among different types of luminescent dopant materials;

[0052] Figures 12 to 14 This is a cross-sectional view showing various arrangement examples between different types of organic light-emitting material layers according to an example embodiment;

[0053] Figure 15 This is a schematic cross-sectional view of the structure of a light-emitting device according to another example embodiment;

[0054] Figure 16 This is a schematic cross-sectional view of the structure of a light-emitting device according to another example embodiment;

[0055] Figure 17 This is a schematic cross-sectional view of the structure of a light-emitting device according to another example embodiment;

[0056] Figure 18 It is shown schematically. Figure 17 A three-dimensional diagram of an example structure of the reflective layer is shown; and

[0057] Figure 19 This is a schematic cross-sectional view illustrating the structure of a display device according to an example embodiment. Detailed Implementation

[0058] The exemplary embodiments are described in more detail below with reference to the accompanying drawings.

[0059] In the following description, similar reference numerals are used for similar elements, even in different figures. The definitions in the description (e.g., detailed constructions and elements) are provided to aid in a comprehensive understanding of the exemplary embodiments. However, it should be understood that the exemplary embodiments can be practiced even in the absence of these specific definitions. Furthermore, well-known functions or constructions are not described in detail because unnecessary detail would obscure the description.

[0060] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of…” modify the entire list of elements when following it, rather than individual elements within 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, all a, b, and c, or any variations of the above examples.

[0061] Although terms such as "first" and "second" can be used to describe various components, these components are not necessarily limited to these terms. The terms may be used only to distinguish one component from another.

[0062] In the layered structure described below, the expressions "above" or "on" can include not only "directly on" in a contact manner but also "on" in a non-contact manner. The singular form encompasses the plural form unless there is a clear difference in meaning in the context. It will also be understood that the terms "comprising" and / or "including" as used herein specify the presence of the described feature or element, but do not preclude the presence or addition of one or more other features or elements.

[0063] The use of “the (described)” and other similar indicator words can correspond to both the singular and plural forms. Unless otherwise expressly mentioned or described, the operations can be performed in any appropriate order. This disclosure is not limited to the mentioned order of operations.

[0064] Terms such as “unit” or “module” used in the embodiments refer to a unit for processing at least one function or operation, and may be implemented in hardware or software, or a combination of hardware and software.

[0065] The connecting lines or connectors shown in the various accompanying figures are intended to illustrate the functional relationships and / or physical or logical couplings between the various components. It should be noted that in actual equipment, there may be many alternative or additional functional relationships, physical connections, or logical connections.

[0066] Any and all examples or language used herein are intended only to better illustrate this disclosure and do not limit the scope of this disclosure unless otherwise required.

[0067] Figure 1 This is a schematic cross-sectional view illustrating the structure of the light-emitting device 100 according to an example embodiment. (Refer to...) Figure 1The light-emitting device 100 may include: a reflective layer 110, including a plurality of periodically arranged two-dimensional nanostructures 112; a first electrode 131 disposed on the reflective layer 110; an organic light-emitting layer 140 disposed on the first electrode 131; and a second electrode 132 disposed on the organic light-emitting layer 140. The light-emitting device 100 may also include a passivation layer 150 disposed on the second electrode 132 to protect the second electrode 132.

[0068] The first electrode 131 disposed on the lower surface of the organic light-emitting layer 140 can be used as an anode to provide holes. The second electrode 132 disposed on the upper surface of the organic light-emitting layer 140 can be used as a cathode to provide electrons. For this purpose, the first electrode 131 may comprise a material with a relatively high work function, and the second electrode 132 may comprise a material with a relatively low work function.

[0069] Alternatively, the first electrode 131 may be a transparent electrode that transmits light (e.g., visible light). For example, the first electrode 131 may comprise a transparent conductive oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), or aluminum zinc oxide (AZO).

[0070] The second electrode 132 can be a semi-transparent electrode that reflects a portion of the light and transmits the remainder. For this purpose, the second electrode 132 can include a very thin reflective metal. For example, the second electrode 132 can include silver (Ag), aluminum (Al), gold (Au), nickel (Ni), or alloys thereof, or can have a bilayer structure of silver (Ag) and magnesium (Mg) or a multilayer structure of aluminum (Al) and lithium (Li). The overall thickness of the second electrode 132 can be from about 10 nm to about 50 nm. Because the second electrode 132 is very thin, some light can pass through the reflective metal.

[0071] The reflective layer 110 can be configured to reflect light generated from the organic light-emitting layer 140 and transmitted through the first electrode 131. Additionally, the reflective layer 110 may comprise a conductive material. For this purpose, the reflective layer 110 may comprise silver (Ag), gold (Au), aluminum (Al), or an alloy comprising silver (Ag), gold (Au), and aluminum (Al). However, the reflective layer 110 is not limited to these materials and may comprise other reflective materials, provided that the reflective layer 110 has high reflectivity and conductivity.

[0072] The reflective layer 110 can form a microcavity 160 together with the second electrode 132. In other words, a microcavity 160 can be formed between the reflective layer 110 and the second electrode 132 of the light-emitting device 100. For example, light generated from the organic light-emitting layer 140 can reciprocate and resonate between the reflective layer 110 and the second electrode 132, and then the light corresponding to the resonant wavelength of the microcavity 160 can be emitted to the outside of the light-emitting device 100 through the second electrode 132.

[0073] The resonant wavelength of the microcavity 160 formed between the reflective layer 110 and the second electrode 132 can be proportional to the optical length L of the microcavity 160. For example, when the resonant wavelength of the microcavity 160 is λ, the optical length L of the microcavity 160 can be nλ / 2 (n is a natural number). The optical length L of the microcavity 160 can be determined as the sum of the optical thickness of the layer forming the microcavity 160 between the reflective layer 110 and the second electrode 132, the phase retardation of the second electrode 132, and the phase shift (e.g., phase retardation) of the reflective layer 110. Here, the optical thickness of the layer forming the microcavity 160 between the reflective layer 110 and the second electrode 132 can be different from the physical thickness of the layer forming the microcavity 160. The optical thickness of the layer refers to the product of the physical thickness of the layer and the refractive index of the layer. For example, the optical thickness of the layer forming the microcavity 160 can be the sum of the optical thickness of the first electrode 131 and the optical thickness of the organic light-emitting layer 140.

[0074] According to an example embodiment, the optical length L or resonant wavelength of the microcavity 160 can be tuned by adjusting only the phase shift caused by the reflective layer 110 while fixing the optical thickness of the layer forming the microcavity 160 and the phase delay of the second electrode 132. To control the phase shift of the reflective layer 110, a phase modulation surface in contact with the first electrode 131 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 metastructure in which nanopatterns with dimensions smaller than the wavelength of visible light are periodically arranged.

[0075] Reference Figure 1 The reflective layer 110 may 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 may include a plurality of nanostructures 112 periodically arranged on the upper surface 114 of the substrate 111. The plurality of nanostructures 112 may have a columnar shape protruding from the upper surface 114 of the substrate 111 toward the first electrode 131. For example, the plurality of nanostructures 112 may have a cylindrical shape. The plurality of nanostructures 112 may be integrally formed with the substrate 111. The reflective layer 110 may be configured such that the upper surfaces of the plurality of nanostructures 112 are in contact with the first electrode 131.

[0076] The optical properties of the phase modulation surface can be determined by the critical dimension W of each of the plurality of nanostructures 112, the height H of each of the nanostructures 112, and the spacing or period P of the plurality of nanostructures 112. For example, when each of the nanostructures 112 is a cylinder, the critical dimension W of each of the nanostructures 112 can be the diameter of each of the nanostructures 112. The diameter of a cylinder can also be referred to as its width. Alternatively, when each of the nanostructures 112 is a polygonal cylinder, the critical dimension W of each of the nanostructures 112 can be the maximum width of each of the nanostructures 112.

[0077] The critical size W, height H, and period P of the nanostructure 112 can be constant relative to the entire region of the phase modulation surface. For example, the critical size W of the nanostructure 112 is about 30 nm to about 250 nm, the height H of the nanostructure 112 is about 0 nm to about 150 nm, and the period P of the multiple nanostructures 112 can be about 100 nm to about 300 nm.

[0078] As described above, when the size of each of the nanostructures 112 on the phase modulation surface is smaller than the resonant wavelength, multiple nano-optical resonant structures can be formed, with the incident light resonating at the periphery of the nanostructures 112. Specifically, in the incident light, the electric field component may not penetrate into the space between the nanostructures 112, and only the magnetic field component can resonate at the periphery of the nanostructures 112. Therefore, the multiple nano-optical resonant structures formed in the space between the nanostructures 112 can be cylindrical resonators, wherein the magnetic field component of the incident light resonates at the periphery of the nanostructures 112. As a result, a phase shift larger than that caused by a simple phase shift due to 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 nanostructure 112 and the refractive index n of the nanostructure 112.

[0079] Therefore, the resonant wavelength of the microcavity 160 can be determined by the critical size W of each of the nanostructures 112 on the phase modulation surface, the height H of each of the nanostructures 112, and the period P of the plurality of nanostructures 112. In other words, when the resonant wavelength of the microcavity 160 is λ, the critical size W of each of the nanostructures 112 on the phase modulation surface, the height H of each of the nanostructures 112, and the period P of the plurality of nanostructures 112 on the phase modulation surface can be selected such that the optical length L of the microcavity 160 is nλ / 2 (n is a natural number).

[0080] Then, the resonant wavelength of the microcavity 160 can be 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 critical size W of each of the nanostructures 112 on the phase modulation surface, the height H of each of the nanostructures 112, and the period P of the multiple nanostructures 112 on the phase modulation surface can be selected so that the resonant wavelength of the microcavity 160 corresponds to the red wavelength band. As described above, the emission wavelength of the light-emitting device 100 can be determined solely by the structure of the phase modulation surface of the reflective layer 110 while fixing the physical length of the microcavity 160 and the internal structure of the organic light-emitting layer 140.

[0081] To prevent the microcavity 160 from becoming polarization-dependent, multiple nanostructures 112 can be arranged regularly and periodically with fourfold symmetry. When the microcavity 160 is polarization-dependent, only light with specific polarization components can resonate, which reduces the luminous efficiency of the light-emitting device 100. For example, Figure 2 It is shown schematically. Figure 1 A perspective view of an example structure of the reflective layer 110 is shown, and Figure 3 It is shown schematically. Figure 1 A perspective view of another example structure of the reflective layer 110 shown. (Refer to...) Figure 2 Multiple cylindrical nanostructures 112 on the upper surface 114 of the substrate 111 can be arranged regularly in a two-dimensional manner. Additionally, referring to... Figure 3 Multiple prismatic nanostructures 112 can be regularly arranged in two dimensions on the upper surface 114 of the substrate 111. Figure 2 and Figure 3 Although the nanostructure 112 can be cylindrical or square, its shape is not limited to these. For example, the nanostructure 112 can be elliptical, pentagonal, or multi-sided.

[0082] In addition, Figure 4 and Figure 5 In this embodiment, multiple nanostructures 112 are arranged in a regular two-dimensional array pattern. In this case, the spacing between two adjacent nanostructures 112 in the entire region of the phase modulation surface can be constant. However, if the multiple nanostructures 112 have 4-fold symmetry, they can be arranged in any other type of array. For example, the multiple nanostructures 112 can be arranged irregularly. In this case, the microcavity 160 may also not be polarization dependent. Meanwhile, in another example embodiment, the arrangement of the multiple nanostructures 112 can be designed to differ from 4-fold symmetry, such that the light-emitting device 100 intentionally emits light with only a specific polarization component. For example, the multiple nanostructures 112 can be arranged in a one-dimensional array pattern.

[0083] The light-emitting device 100 may be an organic light-emitting diode (OLED). Therefore, the organic light-emitting layer 140 may include an organic light-emitting material. For example, Figure 4 It shows in more detail Figure 1 A cross-sectional view of an example structure of the organic light-emitting layer 140 is shown. (Refer to...) Figure 4 The organic light-emitting layer 140 may include: a hole injection layer 142 disposed on the first electrode 131; an organic light-emitting material layer 141 disposed on the hole injection layer 142; and an electron injection layer 143 disposed on the organic light-emitting material layer 141. In this structure, holes provided by the hole injection layer 142 and electrons provided by the electron injection layer 143 can combine in the organic light-emitting material layer 141 to generate light. The wavelength of the generated light can be determined based on the band gap of the light-emitting material in the organic light-emitting material layer 141.

[0084] Additionally, the organic light-emitting layer 140 may further include a hole transport layer 144 disposed between the hole injection layer 142 and the organic light-emitting material layer 141 to further promote hole transport. Furthermore, the organic light-emitting layer 140 may also include an electron transport layer 145 disposed between the electron injection layer 143 and the organic light-emitting material layer 141 to further promote electron transport. Additionally, the organic light-emitting layer 140 may include various additional layers as needed. For example, the organic light-emitting layer 140 may further include an electron blocking layer between the hole transport layer 144 and the organic light-emitting material layer 141, and may also include a hole blocking layer between the organic light-emitting material layer 141 and the electron transport layer 145.

[0085] The organic light-emitting material layer 141 can be configured to emit visible light. For example, the organic light-emitting material layer 141 can be configured to emit all visible light, including red, green, and blue light. In this case, as described above, the emission wavelength emitted from the light-emitting device 100 can be selected by determining the resonant wavelength of the microcavity 160 based on the phase modulation of the phase modulation surface of the reflective layer 110.

[0086] To emit all visible light, including red, green, and blue light, the organic light-emitting material layer 141 may include: a first organic light-emitting material layer 141B, generating light with a first wavelength; a second organic light-emitting material layer 141G, generating light with a second wavelength different from the first wavelength; and a third organic light-emitting material layer 141R, generating light with a third wavelength different from the first and second wavelengths. For example, the first wavelength can be blue light, the second wavelength can be green light, and the third wavelength can be red light. In this case, the first organic light-emitting material layer 141B may be doped with a light-emitting dopant material that emits blue light, the second organic light-emitting material layer 141G may be doped with a light-emitting dopant material that emits green light, and the third organic light-emitting material layer 141R may be doped with a light-emitting dopant material that emits red light.

[0087] Meanwhile, within the cavity structure, the radiation attenuation rate of the light source changes under the influence of the cavity's Q-factor and modulus; this is known as the Purcell effect. Enhancing the Purcell effect can accelerate the radiation attenuation rate of the light source and improve spontaneous emission. Furthermore, considering Fermi's golden rule, to enhance the Purcell effect, in principle, one can adjust the high Q-factor, the highly oriented dopant material in the organic light-emitting material layer, and optimize the position of the organic light-emitting material layer. Specifically, to optimize the position of the organic light-emitting material layer, it can be located at the position with the maximum electric field intensity at the resonant wavelength resonating in the microcavity 160, i.e., at the antinode of the resonant wavelength resonating in the microcavity 160.

[0088] Figure 5 This is a table showing how the luminescence properties of the organic light-emitting material layer vary depending on its position in the organic light-emitting layer 140. Figure 5 The table shows the luminescence characteristics of the red organic light-emitting material layer and the blue organic light-emitting material layer, wherein the red organic light-emitting material layer is disposed at a distance of 60 nm and 70 nm from the second electrode 132, which serves as the cathode, and the blue organic light-emitting material layer is disposed at a distance of 60 nm and 70 nm from the second electrode 132. Furthermore, in Figure 5In the table, emission type "bottom" indicates a lower emission structure in which light is emitted downwards through the first electrode 131 without resonance because there is no reflective layer below the first electrode 131. Emission type "top" indicates an upper emission structure in which light is emitted upwards through the second electrode 132 after resonance occurs because the reflective layer 110 is below the first electrode 131. Due to the phase modulation surface of the reflective layer 110, phase modulation effects are not considered, and it is assumed that the second electrode 132 is Ag and the phase delay caused by the second electrode 132 is 1.3π. Furthermore, it is assumed that the antinodes of the blue wavelength are 42 nm away from the second electrode 132, the antinodes of the green wavelength are 55 nm away, and the antinodes of the red wavelength are 70 nm away.

[0089] Reference Figure 5 As shown in the table, in the lower emission structure where resonance does not occur, the peak intensities of both red and blue light are significantly lower compared to the upper emission structure where resonance occurs. Furthermore, in both the lower and upper emission structures, the peak intensity of red light increases significantly when the red organic light-emitting material layer is 70 nm away from the second electrode 132 compared to when it is 60 nm away, and the peak intensity of blue light decreases when the blue organic light-emitting material layer is 70 nm away from the second electrode 132 compared to when it is 60 nm away. Therefore, it can be seen that the luminous efficiency varies considerably depending on the position of the organic light-emitting material layer.

[0090] Return to reference Figure 4 , Figure 4 The dashed line in the figure represents an example resonant wavelength at which the reflective layer 110 resonates between the second electrode 132. Figure 4 In the example, the resonator length of the microcavity 160 is chosen to have a second-order resonant mode in which two antinodes exist in the microcavity 160. In this case, the first organic light-emitting material layer 141B can be located at the position of the first antinode, which includes the resonant wavelength resonating in the microcavity 160, and the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R can be located at the position of the second antinode, which includes the resonant wavelength resonating in the microcavity 160.

[0091] According to this example embodiment, since the resonant wavelength of the microcavity 160 changes only through phase modulation of the phase modulation surface of the reflective layer 110 when the physical length of the microcavity 160 is fixed, the position of the antinodes in the microcavity 160 can remain almost constant regardless of how the length of the resonant wavelength changes. Therefore, regardless of the emission wavelength of the light-emitting device 100, the first organic light-emitting material layer 141B can be configured to include the first antinode, and the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R can be configured together to include the second antinode. Therefore, when the phase modulation surface of the reflective layer 110 is configured to cause the light-emitting device 100 to emit blue light, the luminous efficiency of the first organic light-emitting material layer 141B that generates blue light can be increased, and when the phase modulation surface of the reflective layer 110 is configured to cause the light-emitting device 100 to emit green or red light, the luminous efficiency of the second organic light-emitting material layer 141G that generates green light and the luminous efficiency of the third organic light-emitting material layer 141R that generates red light can be increased.

[0092] Simultaneously, the organic light-emitting layer 140 may further include a charge-generating layer 146 disposed between the first organic light-emitting material layer 141B and the second organic light-emitting material layer 141G. The charge-generating layer 146 can facilitate charge transfer between the first organic light-emitting material layer 141B and the second organic light-emitting material layer 141G. Additionally, the charge-generating layer 146 can serve as a spacer layer to adjust the positions of the first organic light-emitting material layer 141B, the second organic light-emitting material layer 141G, and the third organic light-emitting material layer 141R. For example, by adjusting the thickness of the charge-generating layer 146, the first organic light-emitting material layer 141B can be located at a position including a first antinode, and the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R can be located at positions including a second antinode.

[0093] The second organic light-emitting material layer 141G can be disposed between the first organic light-emitting material layer 141B and the third organic light-emitting material layer 141R, and can be separated from the first organic light-emitting material layer 141B by the charge generation layer 146. In this structure, the hole injection layer 142 is disposed between the first electrode 131 and the third organic light-emitting material layer 141R, and the electron injection layer 143 is disposed between the first organic light-emitting material layer 141B and the second electrode 132.

[0094] Figure 6 This is a cross-sectional view showing the structure of the organic light-emitting layer 140 according to another example embodiment. Figure 6In the example, the resonator length of the microcavity 160 is chosen to have a three-level resonant mode, in which three antinodes exist in the microcavity 160. In this case, the organic light-emitting layer 140 may also include an additional first organic light-emitting material layer 141B, which is located at the position of the third antinode, which includes the resonant wavelength resonating in the microcavity 160. Additionally, the organic light-emitting layer 140 may also include a charge-generating layer 146 disposed between the additional first organic light-emitting material layer 141B and the third organic light-emitting material layer 141R. The position of the additional first organic light-emitting material layer 141B can be adjusted by the thickness of the charge-generating layer 146 disposed between the additional first organic light-emitting material layer 141B and the third organic light-emitting material layer 141R. The third organic light-emitting layer 141R may be spaced apart from the additional first organic light-emitting layer 141B by the charge-generating layer 146. Figure 6 In the structure shown, the hole injection layer 142 can be disposed between the first electrode 131 and the additional first organic light-emitting material layer 141B.

[0095] The second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R can be arranged adjacent to each other or mixed so that energy can be transferred from the light-emitting dopant material in the second organic light-emitting material layer 141G to the light-emitting dopant material in the third organic light-emitting material layer 141R. For example, in Figure 4 and Figure 6 The diagram shows a second organic light-emitting material layer 141G configured to be in direct, gapless contact with a third organic light-emitting material layer 141R. To transfer energy between the second and third organic light-emitting material layers 141G and 141R, the luminescent dopant materials in both layers can be phosphorescent dopant materials. Simultaneously, the luminescent dopant material in the first organic light-emitting material layer 141B can be a fluorescent dopant material. When the luminescent dopant material in the first organic light-emitting material layer 141B is also a phosphorescent dopant material, the first organic light-emitting material layer 141B can be disposed adjacent to or mixed with the second or third organic light-emitting material layer 141G or 141R, or all of the first to third organic light-emitting material layers 141B, 141G, and 141R can be disposed adjacent to or mixed with each other.

[0096] Figure 7A and Figure 7BThis is a conceptual diagram illustrating energy transfer between different types of luminescent dopant materials. Generally, the radiative decay rate of phosphorescent dopant materials increases with increasing emission wavelength. In other words, as the emission wavelength increases, the phosphorescent dopant material rapidly absorbs energy and emits light. Therefore, phosphorescent dopant materials that produce green light absorb energy more slowly than those that produce red light. When the second organic luminescent material layer 141G (producing green light) and the third organic luminescent material layer 141R (producing red light) are arranged adjacent to each other or mixed, energy transfer can occur between the luminescent dopant materials in the second organic luminescent material layer 141G and the third organic luminescent material layer 141R, while the second organic luminescent material layer 141G absorbs energy and emits green light (… Figure 7A When the second organic light-emitting material layer 141G is not absorbed, the remaining energy is not wasted but transferred to the third organic light-emitting material layer 141R, so that the third organic light-emitting material layer 141R can emit red light. Figure 7B ).

[0097] Figure 8 This is a graph showing how the luminescence characteristics vary depending on the various arrangements between different types of organic light-emitting material layers. Figure 8 In the graph, points marked "single" indicate that the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R exist independently in separate microcavities. Points marked "GBR" indicate that the first organic light-emitting material layer 141B, the second organic light-emitting material layer 141G, and the third organic light-emitting material layer 141R are spaced apart from each other in a microcavity. Points marked "GR" indicate that the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are in direct contact with each other in a microcavity. Points marked "GMR" indicate that the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are partially mixed and disposed in a microcavity. Points marked "Full_mix" indicate that the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are completely mixed and disposed in the same region of a microcavity. (Refer to...) Figure 8 As shown in the graph, with the increase in the mixing degree between the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R, the luminous intensity of red light gradually increases, while the luminous intensity of green light gradually decreases. This is because, before the phosphorescent dopant material in the second organic light-emitting material layer 141G fully absorbs energy, energy is transferred to the phosphorescent dopant material in the third organic light-emitting material layer 141R as the mixing degree between the two layers increases.

[0098] Figure 9 This is a table showing how luminous efficiency varies depending on the various arrangements between different types of organic light-emitting material layers (EMLs), and Figure 10 This is a graph showing how luminous efficiency varies depending on the arrangement of different types of organic light-emitting material layers. (Refer to...) Figure 9 and Figure 10 When the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are separated by approximately 4 nm, the external quantum efficiency (EQE) of the third organic light-emitting material layer 141R is 4.07%, the EQE of the second organic light-emitting material layer 141G is 15.76%, and the overall EQE is 19.83%. Furthermore, when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are in direct contact, the EQE of the third organic light-emitting material layer 141R is 8.52%, the EQE of the second organic light-emitting material layer 141G is 11.96%, and the overall EQE is 20.48%. When the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are partially mixed, the EQE of the third organic light-emitting material layer 141R is 16.89%, the EQE of the second organic light-emitting material layer 141G is 6.57%, and the overall EQE is 23.46%. Furthermore, when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are completely mixed, the EQE in the third organic light-emitting material layer 141R is 18.11%, the EQE in the second organic light-emitting material layer 141G is 3.69%, and the overall EQE is 21.80%.

[0099] Therefore, as the degree of mixing between the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R increases, the EQE of the second organic light-emitting material layer 141G decreases, while the EQE of the third organic light-emitting material layer 141R increases. However, when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are partially mixed, the overall EQE of the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R is the largest. For example, compared with the overall EQE when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are separately disposed, the overall EQE when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are partially mixed increases by about 30%. Therefore, it can be seen that when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are partially mixed (at a preset mixing ratio), rather than when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are set separately, or when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are completely mixed, the overall EQE increases.

[0100] in addition, Figure 11This is a graph showing the relationship between energy transfer rate and luminous efficiency among different types of luminescent dopant materials. Figure 11 In the middle, k G-R This represents the energy transfer rate between the phosphorescent dopant material in the second organic light-emitting material layer 141G and the phosphorescent dopant material in the third organic light-emitting material layer 141R. The energy transfer rate decreases as the mixing degree of the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R decreases, and increases as the mixing degree increases. (Refer to...) Figure 11 It can be seen that there is an energy transfer rate, under which the overall internal quantum efficiency (IQE) of the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R is maximized.

[0101] Therefore, by partially mixing the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R at a preset mixing ratio, the overall luminous efficiency of the light-emitting device 100 can be further improved. Although the intensity of green light decreases when the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R are mixed, the intensity of green light actually emitted from the light-emitting device 100 after resonance in the microcavity is not significantly reduced. Furthermore, the differences in light intensity for each wavelength emitted from the light-emitting device 100 can be compensated by adjusting the voltage applied to the first electrode 131 and the second electrode 132. Therefore, it can be seen that the benefits obtained by further improving the overall luminous efficiency of the light-emitting device 100 are greater.

[0102] Figures 12 to 14 This is a cross-sectional view showing various examples of arrangements between layers of different types of organic light-emitting materials. First, refer to... Figure 12 The second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R can partially overlap. In other words, a hybrid layer 141GR of the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R is disposed between the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R. The second organic light-emitting material layer 141G and the hybrid layer 141GR can be in direct contact with each other without gaps, and the hybrid layer 141GR and the third organic light-emitting material layer 141R can also be in direct contact with each other without gaps.

[0103] exist Figure 12In this structure, only green-emitting dopant material is distributed in the second organic light-emitting material layer 141G, and only red-emitting dopant material is distributed in the third organic light-emitting material layer 141R. Furthermore, both green and red-emitting dopant materials can be distributed together in the mixed layer 141GR. Considering the reduction in green light intensity, the concentration of green-emitting dopant material in the second organic light-emitting material layer 141G and the mixed layer 141GR can be higher than the concentration of red-emitting dopant material in the third organic light-emitting material layer 141R and the mixed layer 141GR. For example, the concentration of green-emitting dopant material can be from about 5% to about 10%, and the concentration of red-emitting dopant material can be from about 2% to about 3%.

[0104] Reference Figure 13 Multiple second organic light-emitting material layers 141G and multiple third organic light-emitting material layers 141R can be arranged alternately in the direction from the second electrode 132 toward the first electrode 131. The multiple second organic light-emitting material layers 141G and multiple third organic light-emitting material layers 141R can be in direct contact with each other without gaps. The thickness of the first second organic light-emitting material layer 141G arranged in the direction from the second electrode 132 toward the first electrode 131 can be greater than the thickness of the subsequent multiple second organic light-emitting material layers 141G. The thickness of the subsequent multiple second organic light-emitting material layers 141G can be the same. Additionally, the thickness of the multiple third organic light-emitting material layers 141R can be the same. Alternatively, when represented in different ways... Figure 13 In the structure shown, it can be assumed that multiple thin-film third organic light-emitting material layers 141R are inserted into the lower region of the second organic light-emitting material layer 141G at regular intervals.

[0105] Considering the reduction in green light intensity, the thickness of each of the second organic light-emitting material layers 141G can be greater than the thickness of each of the third organic light-emitting material layers 141R. For example, the thickness of each of the second organic light-emitting material layers 141G can be from about 5 nm to about 10 nm, and the thickness of each of the third organic light-emitting material layers 141R can be from about 2 nm to about 5 nm. Alternatively, the thickness of each of the second organic light-emitting material layers 141G and the thickness of each of the third organic light-emitting material layers 141R can be the same, and the concentration of green light-emitting dopant material in each of the second organic light-emitting material layers 141G can be higher than the concentration of red light-emitting dopant material in each of the third organic light-emitting material layers 141R.

[0106] Reference Figure 14The third organic light-emitting material layer 141R does not exist alone, but can be mixed with the second organic light-emitting material layer 141G to form a mixed layer 141GR, and disposed in the lower region of the second organic light-emitting material layer 141G. In other words, the third organic light-emitting material layer 141R overlaps with the second organic light-emitting material layer 141G to form the mixed layer 141GR, and is disposed in the lower region of the second organic light-emitting material layer 141G. Therefore, the mixed layer 141GR of the second organic light-emitting material layer 141G and the third organic light-emitting material layer 141R is disposed below the second organic light-emitting material layer 141G. The second organic light-emitting material layer 141G and the mixed layer 141GR can be in direct contact with each other without gaps.

[0107] Figure 15 This is a schematic cross-sectional view illustrating the structure of a light-emitting device 100a according to another example embodiment. (Refer to...) Figure 15 The light-emitting device 100a may include: a reflective layer 110, including a phase modulation surface; a transparent planarization layer 120 disposed on the reflective layer 110; a first electrode 131 disposed on the planarization layer 120; an organic light-emitting layer 140 disposed on the first electrode 131; and a second electrode 132 disposed on the organic light-emitting layer 140. The light-emitting device 100 may also include a passivation layer 150 disposed on the second electrode 132.

[0108] exist Figure 1 In the case of the light-emitting device 100 shown, since the first electrode 131 is directly disposed on the reflective layer 110, the lower surface of the first electrode 131 can have a shape complementary to the phase modulation surface of the reflective layer 110. Figure 15 In the case of the light-emitting device 100a shown, a planarization layer 120 with a flat planar upper surface is provided on the reflective layer 110, and a first electrode 131 is provided on the planarization layer 120. Therefore, the lower surface of the first electrode 131 can have a flat planar shape. In this case, the lower surface of the planarization layer 120 has a shape complementary to the phase modulation surface of the reflective layer 110. The planarization layer 120 may include a conductive material or an insulating material.

[0109] Figure 16 This is a schematic cross-sectional view illustrating the structure of a light-emitting device 100b according to another example embodiment. (Refer to...) Figure 16 The light-emitting device 100b may include a planarization layer 120 having a lower surface and an upper surface with a flat planar shape. In this case, a transparent dielectric 121 may be filled between multiple nanostructures 112 of the reflective layer 110. For example, the transparent dielectric 121 may include air, as well as SiO2, SiN... x At least one of Al2O3 and HfO2.

[0110] Figure 17 This is a schematic cross-sectional view of the structure of a light-emitting device 100c according to another example embodiment. Figure 17 The light-emitting device 100c shown may include a reflective layer 110a, which has a phase modulation surface different from the phase modulation surface of the reflective layer 110.

[0111] Figure 18 It is shown schematically. Figure 17 A perspective view of an example structure of the reflective layer 110a shown. (Refer to...) Figure 17 and Figure 18 The reflective layer 110a may include: a plurality of nanostructures 112 facing the first electrode 131 and protruding on the upper surface 114 of the substrate 111, and arranged periodically; and a plurality of recesses 113 formed by recesses into the upper surface 114 of the substrate 111. The upper surfaces of the plurality of nanostructures 112 may contact the planarization layer 120 or the first electrode 131.

[0112] Each of the nanostructures 112 protruding from the upper surface 114 of the substrate 111 and each of the recesses 113 recessed from the upper surface 114 of the substrate 111 can have a size smaller than the wavelength of visible light. The nanostructures 112 and recesses 113 can be spaced apart, and the area occupied by the upper surface 114 can be larger than the area occupied by the plurality of nanostructures 112 or the plurality of recesses 113. Furthermore, the area occupied by each of the nanostructures 112 can be greater than or equal to the area occupied by each of the recesses 113.

[0113] Multiple nanostructures 112 and multiple recesses 113 can be arranged periodically in a two-dimensional configuration. As described above, the multiple nanostructures 112 can be used to adjust the optical length L of the microcavity 160 to achieve optical resonance corresponding to the emission wavelength of the light-emitting device 100c. The multiple recesses 113 can absorb light with wavelengths that do not need to resonate in the microcavity 160. For this purpose, the multiple recesses 113 can have a diameter of about 80 nm to about 250 nm and a depth of about 100 nm or less. The wavelength of the absorbed light can vary depending on the diameter of each of the recesses 113. The multiple nanoscale recesses 113 are disposed on the phase modulation surface of the reflective layer 110a, so light with wavelengths that do not need to resonate can be further absorbed by the recesses 213. Therefore, the color purity of the light-emitting device 100c can be improved.

[0114] The aforementioned light-emitting devices can be applied to multiple pixels of a display device. Figure 19 This is a schematic cross-sectional view illustrating the structure of a display device 1000 according to an example embodiment. (Refer to...) Figure 19The display device 1000 may include multiple pixels that emit light of different colors. Here, the multiple pixels may include red pixels 1100, green pixels 1200, and blue pixels 1300 arranged adjacent to each other on the same plane of the substrate. Figure 19 For convenience, only one unit pixel including red pixel 1100, green pixel 1200 and blue pixel 1300 is shown, but in reality, a very large number of red pixels 1100, green pixels 1200 and blue pixels 1300 can be arranged repeatedly.

[0115] Red pixel 1100 is shown as having the same... Figure 15 The light-emitting device 100b shown has the same structure, but is not limited thereto. The red pixel 1100 may include: a first reflective layer 110R; a planarization layer 120 disposed on the first reflective layer 110R; a first electrode 131 disposed on the planarization layer 120; an organic light-emitting layer 140 disposed on the first electrode 131; and a second electrode 132 disposed on the organic light-emitting layer 140. The red pixel 1100 may also include a transparent passivation layer 150 disposed on the second electrode 132. The first reflective layer 110R may have multiple nanostructures and may form a first microcavity, which, together with the second electrode 132, causes the red light R to resonate.

[0116] Green pixel 1200 is also shown to have the same... Figure 15 The light-emitting device 100b shown has the same structure, but is not limited thereto. The green pixel 1200 may include: a second reflective layer 110G; a planarization layer 120 disposed on the second reflective layer 110G; a first electrode 131 disposed on the second planarization layer 120; an organic light-emitting layer 140 disposed on the first electrode 131; a second electrode 132 disposed on the organic light-emitting layer 140; and a passivation layer 150 disposed on the second electrode 132. The second reflective layer 110G may have multiple nanostructures and may form a second microcavity, which, together with the second electrode 132, causes the green light G to resonate.

[0117] The blue pixel 1300 may include: a third reflective layer 110B; a planarization layer 120 disposed on the third reflective layer 110B; a first electrode 131 disposed on the planarization layer 120; an organic light-emitting layer 140 disposed on the first electrode 131; a second electrode 132 disposed on the organic light-emitting layer 140; and a passivation layer 150 disposed on the second electrode 132. The upper surface of the third reflective layer 110B in the blue pixel 1300 may include a flat reflective surface. The third reflective layer 110B may form a third microcavity, which, together with the second electrode 132, causes blue light to resonate. For example, the optical length of the third microcavity of the blue pixel 1300 may be determined as the sum of the optical lengths of the materials disposed between the third reflective layer 110B and the second electrode 132.

[0118] Since the emission spectrum can be determined based on the arrangement of the nanostructures of the first reflective layer 110R and the second reflective layer 110G in the display device 1000, the physical thicknesses of the red pixel 1100, green pixel 1200, and blue pixel 1300 can be the same. For example, in the red pixel 1100, green pixel 1200, and blue pixel 1300, all the structures and physical thicknesses of the first electrode 131, organic light-emitting layer 140, second electrode 132, and passivation layer 150 can be identical. Therefore, it is not necessary to form the first electrode 131, organic light-emitting layer 140, second electrode 132, and passivation layer 150 differently for each pixel, thus making it easy to manufacture the display device 1000. In particular, it is easy to increase the area of ​​the display device 1000.

[0119] The aforementioned light-emitting devices and display devices can be applied without restriction to devices of various sizes and for various purposes. For example, they can be applied to display panels of mobile phones or smartphones, display panels of tablet computers or smart tablets, display panels of laptops, televisions or smart TVs, or small display panels used in head-mounted displays, eyeglass displays, and goggle-type displays.

[0120] The above-described light-emitting device and display device including the light-emitting device have been described with reference to exemplary embodiments shown in the accompanying drawings, but these are merely exemplary. The above exemplary embodiments are merely examples and should not be construed as limiting. This teaching can be readily applied to other types of devices. Furthermore, the description of exemplary embodiments is intended to be illustrative and not to limit the scope of the claims, and various alternatives, modifications, and variations will be apparent to those skilled in the art.

Claims

1. A light-emitting device, comprising: The reflective layer comprises multiple nanostructures; The first electrode is disposed on the reflective layer; An organic light-emitting layer is disposed on the first electrode; as well as The second electrode is disposed on the organic light-emitting layer. The reflective layer and the second electrode together form a microcavity with a resonant wavelength. The organic light-emitting layer comprises: a first organic light-emitting material layer configured to generate first light having a first wavelength; a second organic light-emitting material layer configured to generate second light having a second wavelength different from the first wavelength; and a third organic light-emitting material layer configured to generate third light having a third wavelength different from both the first and second wavelengths. The first organic light-emitting material layer is disposed at the position of the first antinode of the resonant wavelength in the microcavity. The second organic light-emitting material layer and the third organic light-emitting material layer are disposed at the positions of the second antinodes of the resonant wavelength resonating in the microcavity. The second organic light-emitting material layer and the third organic light-emitting material layer are adjacent to each other or mixed, so that energy can be transferred from the second light-emitting dopant material in the second organic light-emitting material layer to the third light-emitting dopant material in the third organic light-emitting material layer. The concentration of the second luminescent dopant material in the second organic luminescent material layer is higher than the concentration of the third luminescent dopant material in the third organic luminescent material layer.

2. The light-emitting device according to claim 1, wherein The second organic light-emitting material layer is spaced apart from the first organic light-emitting material layer between the first organic light-emitting material layer and the third organic light-emitting material layer, and is arranged to be in direct contact with the third organic light-emitting material layer.

3. The light emitting device of claim 2, wherein, The organic light-emitting layer further includes: A hole injection layer is located between the first electrode and the third organic light-emitting material layer; A charge-generating layer is located between the first organic light-emitting material layer and the second organic light-emitting material layer; and An electron injection layer is located between the first organic light-emitting material layer and the second electrode.

4. The light-emitting device according to claim 1, wherein The second luminescent dopant material in the second organic luminescent material layer and the third luminescent dopant material in the third organic luminescent material layer are phosphorescent dopant materials, and the first luminescent dopant material in the first organic luminescent material layer is a fluorescent dopant material.

5. The light emitting device of claim 1, wherein, The organic light-emitting layer further includes a hybrid layer of the second organic light-emitting material layer and the third organic light-emitting material layer between the second organic light-emitting material layer and the third organic light-emitting material layer.

6. The light-emitting device according to claim 1, wherein The third organic light-emitting material layer is partially mixed with the second organic light-emitting material layer to form a mixed layer, and the mixed layer is located below the second organic light-emitting material layer.

7. The light-emitting device according to claim 1, wherein The organic light-emitting layer includes a plurality of second organic light-emitting material layers and a plurality of third organic light-emitting material layers, which are arranged alternately in a direction from the second electrode toward the first electrode.

8. The light-emitting device according to claim 7, wherein The thickness of each of the second organic light-emitting material layers is greater than the thickness of each of the third organic light-emitting material layers.

9. The light-emitting device according to claim 1, wherein The organic light-emitting layer further includes an additional first organic light-emitting material layer, which is disposed at the position of the third antinode of the resonant wavelength.

10. The light-emitting device according to claim 9, wherein The organic light-emitting layer further includes a charge-generating layer disposed between the additional first organic light-emitting material layer and the third organic light-emitting material layer.

11. The light-emitting device according to claim 1, wherein, The width, height, and period of each of the plurality of nanostructures in the reflective layer are configured such that the resonant wavelength of the microcavity is consistent with the second wavelength or the third wavelength.

12. The light-emitting device according to claim 11, wherein, The period of the plurality of nanostructures is smaller than the resonant wavelength of the microcavity.

13. 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 that reflects a portion of the light and transmits the remaining portion.

14. A display device, comprising: The first pixel is configured to emit first light having a first wavelength; The second pixel is configured to emit a second light having a second wavelength different from the first wavelength; as well as The third pixel is configured to emit third light having a third wavelength different from the first and second wavelengths. Wherein, at least one of the first pixel, the second pixel, and the third pixel includes: The reflective layer comprises multiple nanostructures; The first electrode is disposed on the reflective layer; An organic light-emitting layer is disposed on the first electrode; and The second electrode is disposed on the organic light-emitting layer. Wherein, when at least one of the first pixel, the second pixel, and the third pixel includes the second pixel, the reflective layer and the second electrode included in the second pixel constitute a microcavity that enables a second light resonance having the second wavelength. The organic light-emitting layer comprises: a first organic light-emitting material layer configured to generate first light having the first wavelength; a second organic light-emitting material layer configured to generate second light having the second wavelength; and a third organic light-emitting material layer configured to generate third light having the third wavelength. The first organic light-emitting material layer is disposed at the position of the first antinode of the resonant wavelength in the microcavity. The second organic light-emitting material layer and the third organic light-emitting material layer are disposed at the position of the second antinode of the resonant wavelength. The second organic light-emitting material layer and the third organic light-emitting material layer are adjacent to each other or mixed, so that energy can be transferred from the second light-emitting dopant material in the second organic light-emitting material layer to the third light-emitting dopant material in the third organic light-emitting material layer. The concentration of the second luminescent dopant material in the second organic luminescent material layer is higher than the concentration of the third luminescent dopant material in the third organic luminescent material layer.

15. The display device according to claim 14, wherein, When at least one of the first pixel, the second pixel, and the third pixel includes the third pixel. The reflective layer included in the third pixel and the second electrode constitute a third microcavity that enables a third light resonance having the third wavelength.

16. The display device according to claim 15, wherein, When at least one of the first pixel, the second pixel, and the third pixel includes the first pixel. The reflective layer included in the first pixel and the second electrode constitute a first microcavity that causes a first light resonating with the first wavelength.

17. The display device according to claim 16, in, The physical thickness of the first pixel, the physical thickness of the second pixel, and the physical thickness of the third pixel are equal to each other.

18. A display device comprising a plurality of pixels, wherein, At least one of the plurality of pixels includes: An organic light-emitting layer, disposed between a first electrode and a second electrode, includes: The first organic light-emitting material layer includes a first light-emitting dopant material, but excludes the second light-emitting dopant material and the third light-emitting dopant material; The second organic light-emitting material layer includes the second light-emitting dopant material, but does not include the first light-emitting dopant material and the third light-emitting dopant material; The third organic light-emitting material layer includes the third light-emitting dopant material, but excludes the first light-emitting dopant material and the second light-emitting dopant material; and A hybrid layer is formed by mixing the second luminescent dopant material with the third luminescent dopant material when the second organic light-emitting material layer and the third organic light-emitting material layer are in direct contact, and is disposed between the second organic light-emitting material layer and the third organic light-emitting material layer. The reflective layer comprises multiple nanostructures, and the first electrode, the organic light-emitting layer, and the second electrode are disposed on the reflective layer. The concentration of the second luminescent dopant material in the second organic luminescent material layer is higher than the concentration of the third luminescent dopant material in the third organic luminescent material layer.

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