Light emitting element and electronic device including display device including the same

Abstract

Embodiments provide a light emitting element and an electronic device including a display device including the light emitting element. The light-emitting element includes: a first electrode; a second electrode facing the first electrode; a lower emission structure disposed between the first electrode and the second electrode and including a first lower functional layer, a first emission layer, and a first upper functional layer; an upper emission structure disposed on the lower emission structure and including a second lower functional layer, a second emission layer, and a second upper functional layer; and a charge generation layer disposed between the lower emission structure and the upper emission structure and including an n-type charge generation layer and a p-type charge generation layer, in which the light-emitting element satisfies Expression 1: [Expression 1] 50 nm > = dTOPgt explained in the specification; d < LOWgt >; and the wavelength is 15 nm.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0034919 filed in the Korean Intellectual Property Office on March 13, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a light emitting element including a plurality of stacked emission structures and an electronic device including a display device including the light emitting element. Background Art

[0004] Development of display devices for various multimedia applications, such as televisions, mobile phones, tablet computers, navigation devices, and game consoles, is continuing. These display devices utilize so-called self-emissive display elements, which achieve display by emitting light from a light-emitting material (which may include an organic compound or quantum dots) in an emissive layer disposed between electrodes facing each other.

[0005] Application of light-emitting elements to display devices requires high luminous efficiency and long life from the light-emitting elements, and there is a need to continuously develop light-emitting elements having a stacked structure and materials for light-emitting elements that can stably achieve high luminous efficiency and long life.

[0006] It should be understood that this background section is intended to provide a useful background for understanding the technology. However, this background section may also include ideas, concepts or cognitions that were not known or understood by those skilled in the art before the effective filing date of the subject matter disclosed herein. Summary of the Invention

[0007] The present disclosure provides a light-emitting element exhibiting improved luminous efficiency and long lifetime.

[0008] The present disclosure also provides an electronic device including a display device including a light emitting element having high luminous efficiency and a long lifespan.

[0009] According to an embodiment, a light-emitting element may include: a first electrode; a second electrode facing the first electrode; a lower emission structure disposed between the first electrode and the second electrode, the lower emission structure including a first lower functional layer, a first emission layer, and a first upper functional layer stacked in sequence; an upper emission structure disposed on the lower emission structure, the upper emission structure including a second lower functional layer, a second emission layer, and a second upper functional layer stacked in sequence; and a charge generation layer disposed between the lower emission structure and the upper emission structure, the charge generation layer including an n-type charge generation layer and a p-type charge generation layer, wherein the light-emitting element may satisfy Expression 1:

[0010] [Expression 1]

[0011] 50nm≥d TOP >d LOW >15nm.

[0012] In Expression 1, d LOW may be the sum of the thickness of the first upper functional layer and the thickness of the n-type charge generation layer; and d TOP It can be the thickness of the second upper functional layer.

[0013] In an embodiment, the first upper functional layer, the second upper functional layer, and the n-type charge generation layer may each include an electron transport material; and the first lower functional layer and the second lower functional layer may each include a hole transport material.

[0014] In an embodiment, the first upper functional layer may include a first electron transport layer, which is directly disposed under the n-type charge generation layer, and a first electron transport auxiliary layer, which is directly disposed under the first electron transport layer; and the second upper functional layer may include a second electron transport auxiliary layer, which is directly disposed on the second emission layer, and a second electron transport layer, which is directly disposed on the second electron transport auxiliary layer.

[0015] In an embodiment, three or more layers selected from the first electron transport layer, the first electron transport auxiliary layer, the n-type charge generation layer, the second electron transport auxiliary layer and the second electron transport layer may each independently include an electron transport material comprising a monocyclic 6-membered heteroaryl group including N as a ring atom.

[0016] In an embodiment, the electron transport material included in at least one layer among the selected three or more layers may include a monocyclic 6-membered heteroaryl group including N as a ring-forming atom and a condensed ring group including 8 or more ring-forming carbon atoms.

[0017] In an embodiment, the fused ring group may be a naphthyl, anthracenyl, fluorenyl, phenanthrenyl, spirobifluorenyl, fluoranthenyl, 1,2-triphenylenyl, quinolyl, quinazolinyl, phenanthrolinyl, triphenylene, carbazolyl, oxaspirobifluorenyl, thiaspirobifluorenyl, pyrenyl, dibenzofuranyl or dibenzothiophenyl.

[0018] In an embodiment, the electron transport material may be a compound selected from Compound Group 1 explained below.

[0019] In an embodiment, the first emission layer and the second emission layer may emit light in the same wavelength region.

[0020] In an embodiment, at least one of the first upper functional layer and the second upper functional layer may each independently include three or more electron transport functional layers; and the electron transport functional layers may each be an electron injection layer, an electron transport layer, or a hole blocking layer.

[0021] In an embodiment, at least one of the first lower functional layer and the second lower functional layer may each independently include three or more hole transport functional layers; and the hole transport functional layers may each be a hole injection layer, a hole transport layer, an electron blocking layer, or an emission auxiliary layer.

[0022] In an embodiment, the light emitting element may further include a capping layer disposed on the second electrode.

[0023] According to an embodiment, a light-emitting element may include: a first electrode; a second electrode facing the first electrode; a plurality of emission structures disposed between the first electrode and the second electrode, each emission structure including a lower functional layer, an emission layer, and an upper functional layer stacked in sequence; and one or more charge generation layers, each charge generation layer being disposed between adjacent emission structures among the plurality of emission structures, and each charge generation layer including an n-type charge generation layer and a p-type charge generation layer, wherein the light-emitting element may satisfy Expression 1:

[0024] [Expression 1]

[0025] 50nm≥d TOP >d LOW >15nm.

[0026] In Expression 1, d LOW may be the sum of the thickness of the upper functional layer of the lower emission structure adjacent to the first electrode and the thickness of the n-type charge generation layer directly disposed on the lower emission structure; and d TOP It may be the thickness of the upper functional layer of the upper emission structure adjacent to the second electrode.

[0027] In an embodiment, the upper functional layer of each emission structure may include an electron transport material; and the lower functional layer of each emission structure may include a hole transport material.

[0028] In an embodiment, the upper functional layer of the upper emission structure may include multiple upper electron transport functional layers; the upper functional layer of the lower emission structure may include multiple lower electron transport functional layers; and three or more layers selected from multiple upper electron transport functional layers, multiple lower electron transport functional layers and an n-type charge generation layer directly arranged on the lower emission structure may each independently include an electron transport material, which electron transport material contains a monocyclic 6-membered heteroaryl group including N as a ring atom.

[0029] In an embodiment, the electron transport material included in at least one layer among the selected three or more layers may include a monocyclic 6-membered heteroaryl group including N as a ring-forming atom and a condensed ring group including 8 or more ring-forming carbon atoms.

[0030] In an embodiment, the electron transport material may be a compound selected from Compound Group 1 explained below.

[0031] According to an embodiment, an electronic device includes a display device, and the display device may include: a red light emitting area, a green light emitting area, and a blue light emitting area separated from each other in a plan view; a circuit layer provided on a base layer; and a display layer provided on the circuit layer, wherein:

[0032] The display layer may include a red light emitting element disposed in a red light emitting region; a green light emitting element disposed in a green light emitting region; and a blue light emitting element disposed in a blue light emitting region.

[0033] The red light emitting element, the green light emitting element and the blue light emitting element may each include: a first electrode; a second electrode facing the first electrode; a lower emission structure disposed between the first electrode and the second electrode, the lower emission structure including a first lower functional layer, a first emission layer and a first upper functional layer stacked in sequence; an upper emission structure disposed on the lower emission structure, the upper emission structure including a second lower functional layer, a second emission layer and a second upper functional layer stacked in sequence; and a charge generation layer disposed between the lower emission structure and the upper emission structure, the charge generation layer including an n-type charge generation layer and a p-type charge generation layer, and

[0034] The display device may satisfy Expression 1:

[0035] [Expression 1]

[0036] 50nm≥d TOP >d LOW >15nm.

[0037] In Expression 1, d LOW may be the sum of the thickness of the first upper functional layer and the thickness of the n-type charge generation layer; and d TOP It can be the thickness of the second upper functional layer.

[0038] In an embodiment, the first upper functional layer may include a first electron transport layer, directly disposed under the n-type charge generation layer, and a first electron transport auxiliary layer, directly disposed under the first electron transport layer; the second upper functional layer may include a second electron transport auxiliary layer, directly disposed on the second emission layer, and a second electron transport layer, directly disposed on the second electron transport auxiliary layer; and three or more layers selected from the first electron transport layer, the first electron transport auxiliary layer, the n-type charge generation layer, the second electron transport auxiliary layer and the second electron transport layer may each independently include an electron transport material, which electron transport material contains a monocyclic 6-membered heteroaryl group including N as a ring atom.

[0039] In an embodiment, the electron transport material included in at least one layer among the selected three or more layers may include a monocyclic 6-membered heteroaryl group including N as a ring-forming atom and a condensed ring group including 8 or more ring-forming carbon atoms.

[0040] In an embodiment, the first lower functional layer, the first upper functional layer, the charge generation layer, the second lower functional layer, and the second upper functional layer may each be provided as a common layer in the red, green, and blue light emitting regions.

[0041] It should be understood that the above embodiments have been described in a general and explanatory sense only and not for purposes of limitation, and that the present disclosure is not limited to the above embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of the specification. The accompanying drawings illustrate the embodiments of the present disclosure and its principles. The above and other aspects and features of the present disclosure will become more apparent by describing the embodiments of the present disclosure in detail with reference to the accompanying drawings, in which:

[0043] Figure 1 is a schematic perspective view of a display device according to an embodiment;

[0044] Figure 2 For a display device according to an embodiment Figure 1 A schematic cross-sectional view taken along the dotted line II';

[0045] Figure 3 For a display device according to an embodiment Figure 1 A schematic cross-sectional view taken along the dotted line II-II';

[0046] Figure 4 is a schematic cross-sectional view of a light emitting element according to an embodiment;

[0047] Figure 5 is a schematic cross-sectional view of a light emitting element according to an embodiment;

[0048] Figure 6 is a schematic cross-sectional view of a light emitting element according to an embodiment; and

[0049] Figure 7 is a schematic cross-sectional view of a portion of a display panel according to an embodiment. DETAILED DESCRIPTION

[0050] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. However, the present disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0051] In the drawings, the size (eg, thickness), proportions, and dimensions of elements may be exaggerated for ease of description and for clarity. Like reference numerals and reference characters refer to like elements throughout.

[0052] In the specification, it will be understood that when an element (or region, layer, portion, etc.) is referred to as being “on,” “connected to,” or “coupled to” another element (or region, layer, portion, etc.), it can be directly on, directly connected to, or directly coupled to the other element (or region, layer, portion, etc.), or one or more intervening elements (or regions, layers, portions, etc.) may be present therebetween. In a similar sense, when an element (or region, layer, portion, etc.) is described as “covering” another element (or region, layer, portion, etc.), it can directly cover the other element (or region, layer, portion, etc.), or one or more intervening elements (or regions, layers, portions, etc.) may be present therebetween.

[0053] In the specification, when an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element, there are no intervening elements present. For example, "directly on" may mean that two layers or two elements are disposed without another element (e.g., an adhesive element) between them.

[0054] As used herein, expressions used in the singular such as "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0055] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. For example, "A and / or B" may be understood to mean "A, B, or A and B." The terms "and" and "or" may be used in a conjunctive or disjunctive sense and may be understood to be equivalent to "and / or."

[0056] In the specification and claims, the term "at least one of" is intended to include the meaning of "at least one selected from the group consisting of" for purposes of its meaning and interpretation. For example, "at least one of A, B, and C" may be understood to mean only A, only B, only C, or any combination of two or more of A, B, and C, such as ABC, ACC, BC, or CC. When following a list of elements, the term "at least one of" modifies the entire list of elements and does not modify the individual elements of the list.

[0057] It will be understood that although the terms first, second, etc. may be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Therefore, without departing from the teachings of the present disclosure, the first element may be referred to as the second element. Similarly, without departing from the scope of the present disclosure, the second element may be referred to as the first element.

[0058] For ease of description, spatially relative terms such as "below," "beneath," "below," "above," or "upper" may be used herein to describe the relationship between one element or component and another element or component as illustrated in the accompanying drawings. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device illustrated in the accompanying drawings is turned over, the device that is located "below" or "beneath" another device may be placed "above" the other device. Accordingly, the illustrative term "below" may include both a lower position and an upper position. The device may also be oriented in other directions, and thus the spatially relative terms may be interpreted differently depending on the orientation.

[0059] As used herein, the term "about" or "approximately" is inclusive of the recited value and means within an acceptable range of deviation for the recited value determined by one of ordinary skill in the art, taking into account the measurement in question and the error associated with the measurement of the stated quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the recited value, or within ±20%, ±10%, or ±5% of the recited value.

[0060] It should be understood that the terms “comprises,” “comprising,” “includes,” “including,” “have,” “having,” “contains,” and “containing” are intended to indicate the presence of the recited features, integers, steps, operations, elements, components, or combinations thereof in the present disclosure, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

[0061] Unless otherwise defined or implied herein, all terms (including technical and scientific terms) used have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the prior art and should not be interpreted in an ideal or overly formal sense unless clearly defined in the specification.

[0062] Hereinafter, a light emitting element according to an embodiment and a display device including the light emitting element according to an embodiment will be described with reference to the accompanying drawings.

[0063] Figure 1 is a schematic perspective view of a display device according to an embodiment. Figure 2 is a schematic cross-sectional view of a display device according to an embodiment. Figure 3 is a schematic cross-sectional view of a display device according to an embodiment. Figure 2 To follow Figure 1 A schematic cross-sectional view taken along the dotted line II', and Figure 3 To follow Figure 1 Schematic cross-sectional view taken along the dotted line II-II'.

[0064] The electronic device according to the embodiment can be activated by an electrical signal. The electronic device may include a display device DD according to the embodiment. Examples of the electronic device may include large devices (such as televisions, monitors, and billboards). Further examples of the electronic device may include small and medium-sized devices (such as personal computers, laptops, personal digital assistants, navigation devices, game consoles, smartphones, tablet computers, and cameras). However, these are presented as examples only, and the electronic device may also be included in other electronic devices.

[0065] The display device DD can display images (or videos) through a display surface DD-IS. The display device DD may include a light-emitting area PXA and a non-light-emitting area NPXA. The display surface DD-IS may be parallel to a plane defined by a first direction axis DR1 and a second direction axis DR2. The display surface DD-IS may include a display area DA and a non-display area NDA. The light-emitting area PXA may be disposed within the display area DA. The light-emitting area PXA may be referred to as a pixel area.

[0066] The non-display area NDA may be defined along the edge of the display surface DD-IS. The non-display area NDA may surround the display area DA. However, embodiments are not limited thereto, and the non-display area NDA may be omitted or provided only on one side of the display area DA.

[0067] Figure 1 The display device DD is shown as having a flat display surface DD-IS, but embodiments are not limited thereto. For example, in embodiments, the display surface DD-IS of the display device DD may be a curved display surface or a three-dimensional display surface. The three-dimensional display surface may include multiple display areas arranged in different directions.

[0068] exist Figures 1 to 7In the specification, the first direction axis DR1, the second direction axis DR2, and / or the third direction axis DR3 are explained. However, the directions indicated by the first to third direction axes DR1, DR2, and DR3 are described in relative terms in the specification and may be changed to other directions. The directions indicated by the first to third direction axes DR1, DR2, and DR3 may be described as the first direction to the third direction, respectively, and may be represented by the same reference numerals or symbols. In the specification, the first direction axis DR1 and the second direction axis DR2 may be perpendicular to each other, and the third direction axis DR3 may be a normal direction to the plane defined by the first direction axis DR1 and the second direction axis DR2. In the specification, a "plan view" may refer to a plane defined by the first direction axis DR1 and the second direction axis DR2, and a "cross-sectional view" may refer to a plane perpendicular to the plane defined by the first direction axis DR1 and the second direction axis DR2 and parallel to the third direction axis DR3. The thickness direction of the display device DD may be a direction parallel to the third direction axis DR3, which is a normal direction to the plane defined by the first direction axis DR1 and the second direction axis DR2.

[0069] In this specification, the upper surface (or front surface) and lower surface (or rear surface) of the components constituting the display device DD may be defined with reference to the third directional axis DR3. For example, of two surfaces facing each other with reference to the third directional axis DR3, the surface relatively close to the display surface DD-IS may be defined as the upper surface (or front surface), and the surface relatively far from the display surface DD-IS may be defined as the lower surface (or rear surface). In this specification, the upper portion (or upper side) and the lower portion (or lower side) may be defined with reference to the third directional axis DR3; the upper portion (or upper side) may be defined on the substrate relatively close to the display surface DD-IS, and the lower portion (or lower side) may be defined on the substrate relatively far from the display surface DD-IS.

[0070] See also Figure 2 and Figure 3 The display device DD may include a display panel DP and an optical member PP disposed on the display panel DP. The display panel DP may include a display layer EDL. The display panel DP may include a base layer BS, a circuit layer DP-CL disposed on the base layer BS, and a display layer EDL disposed on the circuit layer DP-CL. The display layer EDL may include first to third light-emitting elements ED-R, ED-G, and ED-B. The display panel DP may further include an encapsulation layer TFE disposed on the display layer EDL. The encapsulation layer TFE may be disposed directly on the display layer EDL, or another member may be disposed between the display layer EDL and the encapsulation layer TFE.

[0071] The display panel DP may be a component that generates an image. In the display device DD, the display panel DP may be a light-emitting display panel. In an embodiment, the display panel DP may be an organic light-emitting display panel including an organic light-emitting element.

[0072] The optical member PP may be disposed on the display panel DP and may control light reflected at the display panel DP by external light.

[0073] See also Figure 1 and Figure 3 The light emitting area PXA may be provided in the display area DA of the display device DD. The light emitting area PXA may be an area that emits light generated by the first to third light emitting elements ED-R, ED-G, and ED-B, respectively.

[0074] The light emitting areas PXA in the display device DD according to the embodiment may be arranged in a stripe configuration. Figure 1 , the light emitting areas PXA may be arranged along the first direction axis DR1 or the second direction axis DR2. However, the embodiment is not limited thereto. For example, the light emitting areas PXA may be arranged as Configuration or Diamond Configuration.

[0075] Figure 1 and Figure 3 It is illustrated that the light emitting regions PXA all have substantially the same area. However, the embodiment is not limited thereto, and the sizes or shapes of the light emitting regions PXA may be different from each other according to the wavelength range of emitted light.

[0076] The light-emitting area PXA may include a first light-emitting area PXA-R, a second light-emitting area PXA-G, and a third light-emitting area PXA-B. The display device DD may include a plurality of light-emitting areas PXA-R, PXA-G, and PXA-B repeatedly arranged throughout the display area DA. The display device DD may include first to third light-emitting areas PXA-R, PXA-G, and PXA-B separated from each other. The display device DD may include a non-light-emitting area NPXA disposed around and between the first to third light-emitting areas PXA-R, PXA-G, and PXA-B. The non-light-emitting area NPXA defines a boundary between the first to third light-emitting areas PXA-R, PXA-G, and PXA-B. The non-light-emitting area NPXA may surround the first to third light-emitting areas PXA-R, PXA-G, and PXA-B. A structure for preventing color mixing between the first to third emission regions PXA-R, PXA-G, and PXA-B, such as a pixel defining layer PDL, may be provided in the non-emission region NPXA. In a plan view, the first to third emission regions PXA-R, PXA-G, and PXA-B may be spaced apart from each other.

[0077] The first to third light-emitting regions PXA-R, PXA-G, and PXA-B may be regions separated from each other by the pixel-defining layer PDL. The non-light-emitting region NPXA may be a region between the adjacent first to third light-emitting regions PXA-R, PXA-G, and PXA-B and may correspond to the pixel-defining layer PDL.

[0078] The first to third light-emitting regions PXA-R, PXA-G, and PXA-B may each be a region emitting light generated by the first to third light-emitting elements ED-R, ED-G, and ED-B, respectively. In a plan view, the first to third light-emitting regions PXA-R, PXA-G, and PXA-B may be spaced apart from each other.

[0079] In the specification, the first to third light-emitting areas PXA-R, PXA-G, and PXA-B may each correspond to a pixel. The pixel-defining layer PDL may separate the first to third light-emitting elements ED-R, ED-G, and ED-B. The emission structures EU-LR, EU-TR, EU-LG, EU-TG, EU-LB, and EU-TB of the first to third light-emitting elements ED-R, ED-G, and ED-B may be disposed in an opening OH defined by the pixel-defining layer PDL and separated from each other.

[0080] The pixel defining layer (PDL) may be formed of a polymer resin. For example, the pixel defining layer (PDL) may include a polyacrylate resin or a polyimide resin. In an embodiment, in addition to the polymer resin, the pixel defining layer (PDL) may further include an inorganic material. The pixel defining layer (PDL) may further include a light absorbing material, or may further include a black pigment or a black dye. When the pixel defining layer (PDL) includes a black pigment or a black dye, the pixel defining layer (PDL) may be a black pixel defining layer. When forming the pixel defining layer (PDL), carbon black or the like may be used as the black pigment or the black dye, but the embodiment is not limited thereto.

[0081] In an embodiment, the pixel defining layer PDL may include an inorganic material. For example, the pixel defining layer PDL may include an inorganic material (eg, silicon nitride (SiN x ), silicon oxide (SiO x ) or silicon oxynitride (SiO x N y )).

[0082] The first to third light emitting regions PXA-R, PXA-G, and PXA-B may be arranged according to the colors of the lights generated from the first to third light emitting elements ED-R, ED-G, and ED-B. As an example, Figure 3The three light-emitting areas PXA-R, PXA-G, and PXA-B that emit red, green, and blue light, respectively, in the display device DD are explained. For example, in the display device DD according to the embodiment, the first light-emitting area PXA-R may correspond to a red light-emitting area, the second light-emitting area PXA-G may correspond to a green light-emitting area, and the third light-emitting area PXA-B may correspond to a blue light-emitting area.

[0083] In the display device DD according to an embodiment, the first to third light-emitting elements ED-R, ED-G, and ED-B may emit light in different wavelength regions. For example, in an embodiment, the first light-emitting element ED-R may be a red light-emitting element that emits red light, the second light-emitting element ED-G may be a green light-emitting element that emits green light, and the third light-emitting element ED-B may be a blue light-emitting element that emits blue light. For example, the red light-emitting region PXA-R, the green light-emitting region PXA-G, and the blue light-emitting region PXA-B of the display device DD may correspond to the first light-emitting element ED-R, the second light-emitting element ED-G, and the third light-emitting element ED-B, respectively.

[0084] Figure 3 The three light emitting areas PXA-R, PXA-G, and PXA-B separated from each other are illustrated, but the embodiment is not limited thereto, and the display device DD may include four or more light emitting areas each having different light emitting characteristics.

[0085] In the display panel DP, the base layer BS may provide a base surface on which the display layer EDL is disposed. The base layer BS may be a glass substrate, a metal substrate, a plastic substrate, etc. However, the embodiment is not limited thereto, and the base layer BS may include an inorganic layer, an organic layer, or a composite material layer.

[0086] In an embodiment, the circuit layer DP-CL may be provided on the base layer BS, and the circuit layer DP-CL may include transistors (not illustrated). The transistors (not illustrated) may each include a control electrode, an input electrode, and an output electrode. For example, the circuit layer DP-CL may include a switching transistor and a driving transistor for driving the first to third light-emitting elements ED-R, ED-G, and ED-B of the display layer EDL.

[0087] The encapsulation layer TFE may cover the first to third light-emitting elements ED-R, ED-G and ED-B. The encapsulation layer TFE may encapsulate the display layer EDL. The encapsulation layer TFE may be a thin film encapsulation layer. The encapsulation layer TFE may be composed of a single layer, or may include a stack of multiple layers. The encapsulation layer TFE may include at least one insulating layer. The encapsulation layer TFE according to an embodiment may include at least one inorganic film (hereinafter, inorganic encapsulation film). In an embodiment, the encapsulation layer TFE may include at least one organic film (hereinafter, organic encapsulation film) and at least one inorganic encapsulation film.

[0088] The inorganic encapsulation film protects the display layer EDL from moisture and / or oxygen, and the organic encapsulation film protects the display layer EDL from foreign matter (e.g., dust particles). The inorganic encapsulation film may include silicon nitride, silicon oxynitride, silicon oxide, titanium oxide, aluminum oxide, or the like, but embodiments are not limited thereto. The organic encapsulation film may include an acrylic compound, an epoxy compound, or the like. The organic encapsulation film may include a photopolymerizable organic material, but embodiments are not limited thereto.

[0089] The optical member PP may be a glare-reducing layer that reduces the reflectivity of external light. For example, the optical member PP may include a polarizing film including a phase retarder and / or a polarizer, multiple reflective layers that cause destructive interference of reflected light, or filters arranged to correspond to the arrangement of pixels of the display panel DP and the color of light emitted from the pixels of the display panel DP. If the optical member PP includes a filter, the filter may be arranged to take into account the color of light emitted from the pixels included in the display panel DP. In embodiments, the optical member PP may be omitted.

[0090] In an embodiment, the optical member PP may include a base substrate BL and a color filter layer CFL.

[0091] The base substrate BL may provide a base surface on which the color filter layer CFL and the like are disposed. The base substrate BL may be a glass substrate, a metal substrate, a plastic substrate, etc. However, the embodiment is not limited thereto, and the base substrate BL may include an inorganic layer, an organic layer, or a composite material layer.

[0092] The color filter layer CFL may include filters CF-R, CF-G, and CF-B. The color filter layer CFL may include a first filter CF-R, a second filter CF-G, and a third filter CF-B. The first to third filters CF-R, CF-G, and CF-B may be arranged to correspond to the first to third light-emitting elements ED-R, ED-G, and ED-B, respectively. For example, the first filter CF-R may be a red filter, the second filter CF-G may be a green filter, and the third filter CF-B may be a blue filter. The first to third filters CF-R, CF-G, and CF-B may be arranged so that they correspond to the first to third light-emitting areas PXA-R, PXA-G, and PXA-B, respectively.

[0093] The filters CF-R, CF-G, and CF-B, each transmitting a different color of light, can be arranged to overlap the non-luminescent region NPXA disposed between the luminescent regions PXA-R, PXA-G, and PXA-B. The filters CF-R, CF-G, and CF-B can be arranged so that they overlap along the third directional axis DR3, which is the thickness direction, and can be arranged so that they define the boundary between adjacent luminescent regions PXA-R, PXA-G, and PXA-B. This can increase the external light blocking effect, thereby providing the same function as a black matrix. The structure in which the filters CF-R, CF-G, and CF-B overlap can prevent color mixing.

[0094] The first to third optical filters CF-R, CF-G, and CF-B may each include a polymerized photosensitive resin and a pigment or dye. The first optical filter CF-R may include a red pigment or a red dye, the second optical filter CF-G may include a green pigment or a green dye, and the third optical filter CF-B may include a blue pigment or a blue dye. However, embodiments are not limited thereto, and the third optical filter CF-B may not include a pigment or a dye. The third optical filter CF-B may include a polymerized photosensitive resin and may not include a pigment or a dye. The third optical filter CF-B may be transparent. The third optical filter CF-B may be formed of a transparent photosensitive resin.

[0095] The color filter layer CFL may further include a buffer layer BFL. For example, the buffer layer BFL may serve as a protective layer for protecting the first to third color filters CF-R, CF-G, and CF-B. The buffer layer BFL may be an inorganic material layer including at least one of silicon nitride, silicon oxide, and silicon oxynitride. The buffer layer BFL may have a single-layer structure or a multi-layer structure.

[0096] In an embodiment, the first filter CF-R and the second filter CF-G may each be a yellow filter.The first filter CF-R and the second filter CF-G may not be provided as separate filters and may be provided as a single filter.

[0097] Although not shown in the drawings, the color filter layer CFL may further include a light-blocking member (not illustrated). The light-blocking member (not illustrated) may be a black matrix. The light-blocking member (not illustrated) may include an inorganic light-blocking material or an organic light-blocking material, each of which includes a black pigment or a black dye. The light-blocking member (not illustrated) may prevent light leakage and may define boundaries between adjacent color filters CF-R, CF-G, and CF-B.

[0098] Although not shown in the drawings, in an embodiment, the optical member PP may not include the color filter layer CFL.

[0099] In the display device DD according to the embodiment, the first to third light-emitting elements ED-R, ED-G and ED-B may each include: a first electrode AE; a lower emission structure EU-LR, EU-LG or EU-LB; a charge generation layer CGL; an upper emission structure EU-TR, EU-TG or EU-TB; and a second electrode CE. Figure 3 The first to third light-emitting elements ED-R, ED-G, and ED-B are described as each including two emission structures stacked along the third directional axis DR3, which is the thickness direction, but embodiments are not limited thereto. For example, the first to third light-emitting elements ED-R, ED-G, and ED-B may each include three or more emission structures disposed between the first electrode AE ​​and the second electrode CE (stacked in the thickness direction). When the first to third light-emitting elements ED-R, ED-G, and ED-B include three or more emission structures, the first to third light-emitting elements ED-R, ED-G, and ED-B may further include a plurality of charge generation layers, each disposed between adjacent emission structures among the three or more emission structures.

[0100] In an embodiment, the first to third light-emitting elements ED-R, ED-G, and ED-B may include at least one emission layer in each of the lower emission structures EU-LR, EU-LG, and EU-LB and in each of the upper emission structures EU-TR, EU-TG, and EU-TB. For example, the first to third light-emitting elements ED-R, ED-G, and ED-B may each be a light-emitting element having a tandem structure including a plurality of emission layers stacked in a thickness direction.

[0101] In an embodiment, the lower emission structures EU-LR, EU-LG and EU-LB and the upper emission structures EU-TR, EU-TG and EU-TB included in the first to third light-emitting elements ED-R, ED-G and ED-B, respectively, may emit light having the same color. In an embodiment, the lower emission structures EU-LR, EU-LG and EU-LB and the upper emission structures EU-TR, EU-TG and EU-TB included in the first to third light-emitting elements ED-R, ED-G and ED-B, respectively, may emit light in the same wavelength region. For example, the first light-emitting element ED-R may include a lower emission structure EU-LR and an upper emission structure EU-TR, each emitting light in a red wavelength region, the second light-emitting element ED-G may include a lower emission structure EU-LG and an upper emission structure EU-TG, each emitting light in a green wavelength region, and the third light-emitting element ED-B may include a lower emission structure EU-LB and an upper emission structure EU-TB, each emitting light in a blue wavelength region. In the specification, emission of light in the same wavelength region by emission structures stacked in the thickness direction in each light-emitting element can be interpreted as meaning that although the emission wavelengths do not completely match each other, light in a wavelength region in which the light is regarded as having the same color can be emitted.

[0102] The emission structures and charge generation layers included in the first to third light-emitting elements ED-R, ED-G, and ED-B will be described in detail later. The first to third light-emitting elements ED-R, ED-G, and ED-B may further include a capping layer CPL disposed on the second electrode CE. In an embodiment, in addition to the emission structure, the first to third light-emitting elements ED-R, ED-G, and ED-B may further include at least one of a hole injection layer HIL disposed between the first electrode AE ​​and the emission structure and an electron injection layer EIL disposed between the emission structure and the second electrode CE.

[0103] In an embodiment, at least a portion of the first electrode AE ​​may be exposed in the opening OH defined by the pixel defining layer PDL. The first electrode AE ​​has conductivity. The first electrode AE ​​may be formed of a metal material, a metal alloy, or a conductive compound. The first electrode AE ​​may be an anode or a cathode. In an embodiment, the first electrode AE ​​may be a pixel electrode. However, the embodiment is not limited thereto.

[0104] The second electrode CE may be disposed on the first electrode AE. The second electrode CE may be a cathode or an anode. In an embodiment, when the first electrode AE ​​is an anode, the second electrode CE may be a cathode, and when the first electrode AE ​​is a cathode, the second electrode CE may be an anode. The second electrode CE may be a common electrode. However, the embodiment is not limited thereto.

[0105] The lower emission structures EU-LR, EU-LG, and EU-LB may be disposed between the first electrode AE ​​and the charge generation layer CGL, and the upper emission structures EU-TR, EU-TG, and EU-TB may be disposed between the charge generation layer CGL and the second electrode CE.

[0106] Figure 3 It is illustrated that the lower emission structures EU-LR, EU-LG and EU-LB of the first to third light-emitting elements ED-R, ED-G and ED-B and the upper emission structures EU-TR, EU-TG and EU-TB are each completely arranged in the opening OH. However, this is only an example. In an embodiment, in the lower emission structures EU-LR, EU-LG and EU-LB and the upper emission structures EU-TR, EU-TG and EU-TB, some components may be patterned and arranged in the opening OH, and other components may be provided as a common layer throughout the first to third light-emitting areas PXA-R, PXA-G and PXA-B. In another embodiment, in the lower emission structures EU-LR, EU-LG and EU-LB and the upper emission structures EU-TR, EU-TG and EU-TB, at least some components may be provided by extending above the pixel defining layer PDL, or at least some components may be connected to each other.

[0107] In the display device DD, the lower emission structures EU-LR, EU-LG, and EU-LB of the first to third light-emitting elements ED-R, ED-G, and ED-B, and the upper emission structures EU-TR, EU-TG, and EU-TB, etc., can each be formed by patterning using an inkjet printing method. However, the embodiment is not limited thereto. The lower emission structures EU-LR, EU-LG, and EU-LB, and the upper emission structures EU-TR, EU-TG, and EU-TB can be formed by methods other than inkjet printing.

[0108] In the display device DD, the second electrode CE and the capping layer CPL may each be provided as a common layer throughout the first to third light-emitting elements ED-R, ED-G, and ED-B. However, the embodiment is not limited thereto, and at least one of the second electrode CE and the capping layer CPL may be provided by patterning in the opening OH in each of the light-emitting regions PXA-R, PXA-G, and PXA-B.

[0109] Figures 4 to 6 Each is a schematic cross-sectional view of a light emitting element according to an embodiment. Figures 4 to 6 Each shows a structure of a light emitting element according to an embodiment. In the embodiment, Figure 3 The first to third light emitting elements ED-R, ED-G and ED-B explained in the above may each independently have the following characteristics: Figures 4 to 6 The structure of the light-emitting element ED, ED-a or ED-1 explained in .

[0110] Figure 4 and Figure 5 Each explains an embodiment of a light emitting element including two emission structures stacked between a first electrode AE ​​and a second electrode CE. Figure 6 An embodiment of a light emitting element including three or more emission structures stacked between the first electrode AE ​​and the second electrode CE is explained.

[0111] according to Figure 4 In the embodiment illustrated in FIG, the light emitting element ED may include a first electrode AE, a hole injection layer HIL, a lower emission structure EU-B, a charge generation layer CGL, an upper emission structure EU-T, an electron injection layer EIL, a second electrode CE, and a capping layer CPL stacked in the following order on the third direction axis DR3. Figure 5 In the embodiment illustrated in the figure, the light emitting element ED-a may include a first electrode AE, a hole injection layer HIL, a lower emission structure EU-Ba, a charge generation layer CGL, an upper emission structure EU-Ta, an electron injection layer EIL, a second electrode CE and a capping layer CPL stacked in the following order on the third direction axis DR3. Figure 5 The light-emitting element ED-a explained in Figure 4 The light emitting elements ED explained in the accompanying drawings may differ at least in the configuration of sub-functional layers included in the lower functional layers LFL-B, LFL-Ba, LFL-T and LFL-Ta and the upper functional layers UFL-B, UFL-Ba, UFL-T and UFL-Ta.

[0112] according to Figure 6 The light emitting element ED-1 of the embodiment illustrated in the embodiment may include n emission structures EU1, EU2, ... and EUn between the first electrode AE ​​and the second electrode CE. The light emitting element ED-1 may include the first electrode AE, a hole injection layer HIL, n emission structures EU1, EU2, ... and EUn, (n-1) charge generation layers CGL1, CGL2, ... and CGL(n-1), an electron injection layer EIL, a second electrode CE and a capping layer CPL. Figure 6In the embodiment illustrated in , n may be an integer equal to or greater than 3. Each of the n emission structures EU1, EU2, ... and EUn may include lower functional layers LFL-1, LFL-2, ... and LFL-n, emission layers EML-1, EML-2, ... and EML-n, and upper functional layers UFL-1, UFL-2, ... and UFL-n. In addition, each of the (n-1) charge generation layers CGL1, CGL2, ... and CGL(n-1) may include n-type charge generation layers nCGL1, nCGL2, ... and nCGL(n-1) and p-type charge generation layers pCGL1, pCGL2, ... and pCGL(n-1). The charge generation layers CGL1, CGL2, ... and CGL(n-1) may each be arranged between adjacent emission structures among the emission structures EU1, EU2, ... and EUn. For example, the first charge generation layer CGL1 may be disposed between the first emission structure EU1 and the second emission structure EU2, the second charge generation layer CGL2 may be disposed on the second emission structure EU2, and the (n-1)th charge generation layer CGL(n-1) may be disposed under the nth emission structure EUn.

[0113] In different Figures 4 to 6 In the light-emitting elements ED, ED-a, and ED-1 described in

[15] , the first electrode AE ​​may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. The first electrode AE ​​may include at least one of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, W, In, Sn, and Zn, or an oxide, compound, or mixture thereof.

[0114] When the first electrode AE ​​is a transmissive electrode, the first electrode AE ​​may include a transparent metal oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), or the like. When the first electrode AE ​​is a semi-transmissive electrode or a reflective electrode, the first electrode AE ​​may include at least one of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, Yb, and W, a compound thereof, or a mixture thereof (e.g., a mixture of Ag and Mg), or a multilayer structure material such as LiF / Ca (a stacked structure of LiF and Ca) or LiF / Al (a stacked structure of LiF and Al). In embodiments, the first electrode AE ​​may have a multilayer structure including a reflective film or a semi-transmissive film formed of the above materials and a transparent conductive film formed of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), or the like. For example, the first electrode AE ​​may have a three-layer structure of ITO / Ag / ITO, but the embodiment is not limited thereto. In an embodiment, the first electrode AE ​​may include the metal material described above, a combination of two or more metal materials described above, or an oxide of the metal material described above, but the embodiment is not limited thereto. The thickness of the first electrode AE ​​may be about 1000 Å. to about For example, the thickness of the first electrode AE ​​may be about to about within the range.

[0115] The second electrode CE may include at least one of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, W, In, Sn, and Zn, an oxide thereof, a compound thereof, or a mixture thereof.

[0116] The second electrode CE may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. When the second electrode CE is a transmissive electrode, the second electrode CE may include a transparent metal oxide, such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), etc.

[0117] When the second electrode CE is a semi-transmissive electrode or a reflective electrode, the second electrode CE may include at least one of Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF, Mo, Ti, Yb, and W, a compound thereof, or a mixture thereof (e.g., AgMg, AgYb, or MgYb), or a multilayer structure material such as LiF / Ca (a stacked structure of LiF and Ca) or LiF / Al (a stacked structure of LiF and Al). In an embodiment, the second electrode CE may have a multilayer structure including a reflective film or a semi-transmissive film formed of the above materials and a transparent conductive film formed of indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium tin zinc oxide (ITZO), or the like. For example, the second electrode CE may include the metal materials described above, a combination of two or more metal materials described above, or an oxide of the metal materials described above.

[0118] Although not shown in the drawings, the second electrode CE may be electrically connected to an auxiliary electrode (not illustrated). The auxiliary electrode (not illustrated) may be formed by the circuit layer DP-CL ( Figure 3 When the second electrode CE is electrically connected to the auxiliary electrode (not illustrated), the resistance of the second electrode CE can be reduced.

[0119] The light emitting elements ED, ED-a, and ED-1 of the embodiment may include a capping layer CPL disposed on the second electrode CE. The capping layer CPL may have a multi-layer structure or a single-layer structure.

[0120] In an embodiment, the capping layer CPL may include an organic layer or an inorganic layer. For example, when the capping layer CPL includes an inorganic material, the inorganic material may include an alkali metal compound (eg, LiF), an alkaline earth metal compound (eg, MgF2), SiON, SiN x 、SiO y wait.

[0121] For example, when the capping layer CPL includes an organic material, the organic material may include NPB (or NPD, α-NPD), TPD, m-MTDATA, Alq3, CuPc, N4,N4,N4',N4'-tetrakis(biphenyl-4-yl)biphenyl-4,4'-diamine (TPD15), 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), etc., or may include epoxy resin or acrylate (eg, methacrylate). However, embodiments are not limited thereto, and the capping layer CPL may include at least one of compounds P1 to P5:

[0122]

[0123] The refractive index of the capping layer CPL may be equal to or greater than about 1.6. For example, with respect to light in a wavelength range of about 550 nm to about 660 nm, the refractive index of the capping layer CPL may be equal to or greater than about 1.6. In embodiments, the capping layer CPL may be omitted in the light-emitting elements ED, ED-a, and ED-1.

[0124] See also Figure 4 In the light-emitting element ED shown in FIG, the lower emission structure EU-B may include a first lower functional layer LFL-B, a first emission layer EML-B and a first upper functional layer UFL-B stacked in the following order from the first electrode AE, and the upper emission structure EU-T may include a second lower functional layer LFL-T, a second emission layer EML-T and a second upper functional layer UFL-T stacked in the following order from the charge generation layer CGL.

[0125] See also Figure 5 In the light-emitting element ED-a shown in FIG, the lower emission structure EU-Ba may include a first lower functional layer LFL-Ba, a first emission layer EML-B and a first upper functional layer UFL-Ba stacked in the following order from the first electrode AE, and the upper emission structure EU-Ta may include a second lower functional layer LFL-Ta, a second emission layer EML-T and a second upper functional layer UFL-Ta stacked in the following order from the charge generation layer CGL.

[0126] exist Figure 4 and Figure 5 In the embodiment, the upper functional layers UFL-B, UFL-T, UFL-Ba and UFL-Ta can each be an electron transport functional layer performing an electron injection function or an electron transport function; and the lower functional layers LFL-B, LFL-Ba, LFL-T and LFL-Ta can each be a hole transport functional layer performing a hole injection function or a hole transport function.

[0127] exist Figure 4 and Figure 5, the upper functional layers UFL-B, UFL-T, UFL-Ba and UFL-Ta may each have a multilayer structure having multiple layers. The upper functional layers UFL-B, UFL-T, UFL-Ba and UFL-Ta may each have a multilayer structure having multiple layers including different materials. In an embodiment, the upper functional layers UFL-B, UFL-T, UFL-Ba and UFL-Ta may each independently have an electron transport layer / electron injection layer structure, a buffer layer / electron transport layer structure, a hole blocking layer / electron transport layer / electron injection layer structure, etc., wherein the layers of each structure are stacked from the emission layers EML-B and EML-T in the order described respectively, but the embodiment is not limited thereto. In the specification, the buffer layer may be referred to as an electron transport layer or an auxiliary electron transport layer. The buffer layer may perform a supplementary electron transport function. The hole blocking layer may prevent holes from being injected from the hole transport functional layer to the electron transport functional layer.

[0128] exist Figure 4 and Figure 5 In the embodiment, the lower functional layers LFL-B, LFL-Ba, LFL-T, and LFL-Ta may each independently have a structure consisting of a single layer (composed of a single material), a structure consisting of a single layer including different materials, or a structure including multiple layers including different materials. For example, the lower functional layers LFL-B, LFL-Ba, LFL-T, and LFL-Ta may each have a single-layer structure of a hole injection layer or a hole transport layer, or may each have a single-layer structure including a hole injection material and a hole transport material. In an embodiment, the lower functional layers LFL-B, LFL-Ba, LFL-T and LFL-Ta may each have a single-layer structure including different materials, or may each independently have a hole injection layer / hole transport layer structure, a hole injection layer / hole transport layer / emission auxiliary layer structure, a hole injection layer / emission auxiliary layer structure, a hole transport layer / emission auxiliary layer structure, a hole injection layer / hole transport layer / emission auxiliary layer structure or a hole injection layer / hole transport layer / emission auxiliary layer structure, wherein the layers of each structure are stacked from the first electrode AE ​​and the charge generation layer CGL in the order of their respective descriptions, but the embodiment is not limited thereto.

[0129] The emission-assisting layer can compensate for the resonance distance according to the wavelength of light emitted from the emission layers EML-B and EML-T, and can adjust the hole-electron balance, thereby increasing luminous efficiency. The emission-assisting layer can include a hole transport material. The electron blocking layer can also prevent electrons from being injected from the electron transport functional layer into the hole transport functional layer.

[0130] exist Figure 4In the light-emitting element ED described in

[15] , the first upper functional layer UFL-B may have a stacked structure of a first electron transport auxiliary layer BFL-B and a first electron transport layer ETL-B, and the second upper functional layer UFL-T may have a stacked structure of a second electron transport auxiliary layer BFL-T and a second electron transport layer ETL-T. In embodiments, the first electron transport auxiliary layer BFL-B and the second electron transport auxiliary layer BFL-T may each independently function as an electron transport layer, a buffer layer, or a hole blocking layer.

[0131] exist Figure 4 In the light emitting element ED explained in , the first lower functional layer LFL-B and the second lower functional layer LFL-T may each have a single layer structure. Figure 4 In the embodiment, the first lower functional layer LFL-B may function as a hole transport layer, and the second lower functional layer LFL-T may function as an emission assisting layer.

[0132] and Figure 4 Compared with the light emitting element ED explained in Figure 5 In the light-emitting element ED-a described in [1], the lower functional layers LFL-Ba and LFL-Ta and the upper functional layers UFL-Ba and UFL-Ta may each include three sub-functional layers. The first lower functional layer LFL-Ba may include first to third lower sub-functional layers HFL1-B, HFL2-B, and HFL3-B, and the first upper functional layer UFL-Ba may include first to third upper sub-functional layers EFL1-B, EFL2-B, and EFL3-B. The second lower functional layer LFL-Ta may include fourth to sixth lower sub-functional layers HFL1-T, HFL2-T, and HFL3-T, and the second upper functional layer UFL-Ta may include fourth to sixth upper sub-functional layers EFL1-T, EFL2-T, and EFL3-T.

[0133] exist Figure 5 In the light-emitting element ED-a illustrated in FIG, the first upper functional layer UFL-Ba may include a first upper sub-functional layer EFL1-B, a second upper sub-functional layer EFL2-B, and a third upper sub-functional layer EFL3-B, which are disposed on the first emission layer EML-B and are sequentially disposed in a direction from the charge generation layer CGL to the first emission layer EML-B. In an embodiment, the first to third upper sub-functional layers EFL1-B, EFL2-B, and EFL3-B may each be an electron transport functional layer.

[0134] In an embodiment, the first upper sub-functional layer EFL1-B may function as an electron transport layer or an electron injection layer; and the second upper sub-functional layer EFL2-B and the third upper sub-functional layer EFL3-B may each independently function as an electron transport layer, a buffer layer, or a hole blocking layer. For example, in an embodiment, the first upper sub-functional layer EFL1-B may be an electron transport layer, the second upper sub-functional layer EFL2-B may be a buffer layer, and the third upper sub-functional layer EFL3-B may be a hole blocking layer. However, embodiments are not limited thereto.

[0135] exist Figure 5 In the light-emitting element ED-a illustrated in FIG, the second upper functional layer UFL-Ta may include a fourth upper subfunctional layer EFL1-T, a fifth upper subfunctional layer EFL2-T, and a sixth upper subfunctional layer EFL3-T disposed on the second emission layer EML-T and sequentially arranged in a direction from the second electrode CE to the second emission layer EML-T. In an embodiment, the fourth to sixth upper subfunctional layers EFL1-T, EFL2-T, and EFL3-T may each be an electron transport subfunctional layer.

[0136] In an embodiment, the fourth upper sub-functional layer EFL1-T may function as an electron transport layer or an electron injection layer; and the fifth upper sub-functional layer EFL2-T and the sixth upper sub-functional layer EFL3-T may each independently function as an electron transport layer, a buffer layer, or a hole blocking layer. For example, in an embodiment, the fourth upper sub-functional layer EFL1-T may be an electron transport layer, the fifth upper sub-functional layer EFL2-T may be a buffer layer, and the sixth upper sub-functional layer EFL3-T may be a hole blocking layer. However, embodiments are not limited thereto.

[0137] exist Figure 5 In the light-emitting element ED-a described in

[15] , the first lower functional layer LFL-Ba may include a first sub-functional layer HFL1-B, a second lower sub-functional layer HFL2-B, and a third lower sub-functional layer HFL3-B, which are disposed below the first emission layer EML-B and sequentially arranged in a direction from the first emission layer EML-B to the first electrode AE. In an embodiment, the first to third lower sub-functional layers HFL1-B, HFL2-B, and HFL3-B may each be a hole transport functional layer.

[0138] In embodiments, the first sub-functional layer HFL1-B and the second lower sub-functional layer HFL2-B may each independently function as a hole transport layer, an emission-assisting layer, or an electron blocking layer; and the third lower sub-functional layer HFL3-B may function as a hole transport layer or a hole injection layer. For example, in embodiments, the first sub-functional layer HFL1-B may be an emission-assisting layer or an electron blocking layer, the second lower sub-functional layer HFL2-B may be a hole transport layer, and the third lower sub-functional layer HFL3-B may be a hole transport layer or a hole injection layer. However, embodiments are not limited thereto.

[0139] exist Figure 5 In the light-emitting element ED-a described in

[15] , the second lower functional layer LFL-Ta may include a fourth lower sub-functional layer HFL1-T, a fifth lower sub-functional layer HFL2-T, and a sixth lower sub-functional layer HFL3-T, which are disposed below the second emission layer EML-T and sequentially arranged in a direction from the second emission layer EML-T to the charge generation layer CGL. In an embodiment, the fourth to sixth lower sub-functional layers HFL1-T, HFL2-T, and HFL3-T may each be a hole transport functional layer.

[0140] In an embodiment, the fourth lower sub-functional layer HFL1-T and the fifth lower sub-functional layer HFL2-T may each independently function as a hole transport layer, an emission-assisting layer, or an electron blocking layer; and the sixth lower sub-functional layer HFL3-T may function as a hole transport layer or a hole injection layer. For example, in an embodiment, the fourth lower sub-functional layer HFL1-T may function as an emission-assisting layer, an electron blocking layer, or a hole transport layer, the fifth lower sub-functional layer HFL2-T may function as a hole transport layer, and the sixth lower sub-functional layer HFL3-T may function as a hole transport layer or a hole injection layer. However, embodiments are not limited thereto.

[0141] See also Figure 4 and Figure 5, the light-emitting elements ED and ED-a may each include a charge generation layer CGL arranged between the lower emission structure EU-B and the upper emission structure EU-T, and a charge generation layer CGL arranged between the lower emission structure EU-Ba and the upper emission structure EU-Ta. When voltage is applied to the light-emitting elements ED and ED-a, the charge generation layer CGL may generate charges (electrons and holes) by forming a complex through an oxidation-reduction reaction. The charge generation layer CGL may provide generated charges for each of the adjacent lower emission structures EU-B and EU-Ba and the upper emission structures EU-T and EU-Ta. The charge generation layer CGL may increase the efficiency of the current generated in each of the adjacent emission structures EU-B, EU-Ba, EU-T and EU-Ta, and may control the balance of charges between the adjacent emission structures EU-B and EU-T and EU-Ba and EU-Ta. The charge generation layer CGL may include an n-type charge generation layer nCGL and a p-type charge generation layer pCGL. The charge generation layer CGL may have a structure in which the n-type charge generation layer nCGL and the p-type charge generation layer pCGL are combined with each other.

[0142] The n-type charge generation layer nCGL may be a charge generation layer that provides electrons to the adjacent emission structures EU-B and EU-Ba. The n-type charge generation layer nCGL may include a base material doped with an n-dopant. The p-type charge generation layer pCGL may be a charge generation layer that provides holes to the adjacent emission structures EU-T and EU-Ta. The p-type charge generation layer pCGL may include a base material doped with a p-dopant. In an embodiment, the charge generation layer CGL may further include a buffer layer (not illustrated) disposed between the n-type charge generation layer nCGL and the p-type charge generation layer pCGL. For example, in an embodiment, the n-type charge generation layer nCGL may be an electron transport functional layer that performs an electron transport function, and the p-type charge generation layer pCGL may be a hole transport functional layer that performs a hole transport function.

[0143] According to the embodiment, Figure 4 The light emitting element ED explained in the above may satisfy Expression 1:

[0144] [Expression 1]

[0145] 50nm≥d TOP >d LOW >15nm.

[0146] In Expression 1, d LOW The thickness of the first upper functional layer UFL-B can be ETL and the thickness of the n-type charge generation layer nCGL t CGL and d TOP It can be the thickness of the second upper functional layer UFL-T.

[0147] Therefore, in the light-emitting element ED, the thickness of the second upper functional layer UFL-T (wherein the second upper functional layer UFL-T is arranged to be adjacent to the second electrode CE) including the second electron transport layer ETL-T and the second electron transport auxiliary layer BFL-T that performs an electron transport function in the upper emission structure EU-T) may be greater than the sum of the thickness of the n-type charge generation layer nCGL, the thickness of the first electron transport layer ETL-B and the thickness of the first electron transport auxiliary layer BFL-B that performs an electron transport function in the lower emission structure EU-B, where the n-type charge generation layer nCGL, the first electron transport layer ETL-B and the first electron transport auxiliary layer BFL-B are arranged between the upper emission structure EU-T and the first electrode AE.

[0148] When the light-emitting element ED satisfies the thickness relationship of Expression 1, excitons can be effectively formed in each of the emission structures EU-B and EU-T, so that the movement distance of the charge to the adjacent layer that is not the emission layer can be reduced. The thickness of the electron transport functional layer in the lower emission structure EU-B can be less than the thickness of the electron transport functional layer in the upper emission structure EU-T, and therefore, the increase and overshoot of the driving voltage can be suppressed, thereby facilitating low power consumption and improved driving life. Accordingly, the light-emitting element ED can exhibit excellent luminous efficiency and long life characteristics, and the display device including the light-emitting element ED can exhibit excellent display quality and long life characteristics.

[0149] In the light emitting element ED, the first upper functional layer UFL-B, the second upper functional layer UFL-T and the n-type charge generation layer nCGL may each include an electron transport material, and the first lower functional layer LFL-B and the second lower functional layer LFL-T may each include a hole transport material.

[0150] The first upper functional layer UFL-B, the second upper functional layer UFL-T, and the n-type charge generation layer nCGL may each include at least one sub-functional layer, and three or more layers selected from the sub-functional layers included in the first upper functional layer UFL-B, the second upper functional layer UFL-T, and the n-type charge generation layer nCGL may each independently include an electron transport material, wherein the electron transport material includes a monocyclic 6-membered heteroaryl group including N as a ring-forming atom. For example, the three or more layers selected from the sub-functional layers performing an electron transport function may each independently include at least one monocyclic 6-membered heteroaryl group including N as a ring-forming atom. For example, the monocyclic 6-membered heteroaryl group including N as a ring-forming atom may be pyridine, pyrimidine, or triazine.

[0151] The first upper functional layer UFL-B, the second upper functional layer UFL-T, and the n-type charge generation layer nCGL may each include at least one sub-functional layer, and at least one sub-functional layer may include an electron transport material comprising a monocyclic 6-membered heteroaryl group including N as a ring-forming atom and a condensed ring group including 8 or more ring-forming carbon atoms. In an embodiment, among the sub-functional layers included in the first upper functional layer UFL-B, the second upper functional layer UFL-T, and the n-type charge generation layer nCGL, three or more sub-functional layers selected therefrom may each independently include an electron transport material comprising at least one monocyclic 6-membered heteroaryl group including N as a ring-forming atom; and among the three or more sub-functional layers selected therefrom, the electron transport material included in at least one sub-functional layer thereof may include: a monocyclic 6-membered heteroaryl group including N as a ring-forming atom; and a condensed ring group including 8 or more ring-forming carbon atoms.

[0152] In an embodiment, at least one of the electron transport materials included in the electron transport functional layer may be a compound including the following two: a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms. In an embodiment, the condensed ring group may be naphthyl, anthracenyl, fluorenyl, phenanthrenyl, spirobifluorenyl, fluoranthenyl, 1,2-triphenylenyl, quinolyl, quinazolinyl, phenanthrolinyl, triphenylene, carbazolyl, oxaspirobifluorenyl, thiaspirobifluorenyl, pyrenyl, dibenzofuranyl or dibenzothiophenyl. However, the embodiment is not limited thereto.

[0153] In an embodiment, the first upper functional layer UFL-B may include a first electron transport layer ETL-B directly disposed under the n-type charge generation layer nCGL and a first electron transport auxiliary layer BFL-B directly disposed under the first electron transport layer ETL-B; and the second upper functional layer UFL-T may include a second electron transport auxiliary layer BFL-T directly disposed on the second emission layer EML-T and a second electron transport layer ETL-T directly disposed on the second electron transport auxiliary layer BFL-T.

[0154] exist Figure 4 In the light-emitting element ED described in , three or more layers selected from the first electron transport layer ETL-B, the first electron transport auxiliary layer BFL-B, the n-type charge generation layer nCGL, the second electron transport auxiliary layer BFL-T, and the second electron transport layer ETL-T may each independently include an electron transport material, wherein the electron transport material includes a monocyclic 6-membered heteroaryl group including N as a ring atom. In an embodiment, at least one layer among the selected three or more layers may include an electron transport material, wherein the electron transport material includes both the following: a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms.

[0155] According to the embodiment, Figure 5 The light-emitting element ED-a explained in can also satisfy Expression 1:

[0156] [Expression 1]

[0157] 50nm≥d TOP >d LOW >15nm.

[0158] In Expression 1, d LOW may be the sum of the thickness of the first upper functional layer UFL-Ba and the thickness of the n-type charge generation layer nCGL; and d TOP It can be the thickness of the second upper functional layer UFL-Ta. Figure 5 The light-emitting element ED-a explained in the embodiment can also satisfy the thickness relationship of Expression 1, wherein the first upper functional layer UFL-Ba is the electron transport functional layer of the lower emission structure EU-Ba, the second upper functional layer UFL-Ta is the electron transport functional layer of the upper emission structure EU-Ta, and the first upper functional layer UFL-Ba and the second upper functional layer UFL-Ta each include three or more sub-functional layers.

[0159] In the light-emitting element ED-a, the thickness of the second upper functional layer UFL-Ta (wherein the upper emission structure EU-Ta is arranged adjacent to the second electrode CE) including the electron transport sub-functional layers EFL1-T, EFL2-T and EFL3-T that perform an electron transport function in the upper emission structure EU-Ta may be greater than the sum of the thicknesses of the n-type charge generation layer nCGL and each of the electron transport sub-functional layers EFL1-B, EFL2-B and EFL3-B that perform an electron transport function in the lower emission structure EU-Ba, wherein the n-type charge generation layer nCGL and the electron transport sub-functional layers EFL1-B, EFL2-B and EFL3-B are arranged between the upper emission structure EU-Ta and the first electrode AE.

[0160] When the light-emitting element ED-a satisfies the thickness relationship of Expression 1, excitons can be effectively formed in each emission structure EU-Ba and EU-Ta, so that the movement distance of the charge to the adjacent layer that is not the emission layer can be reduced. Accordingly, the light-emitting element ED-a can exhibit excellent luminous efficiency and long life characteristics. The thickness of the electron transport functional layer in the lower emission structure EU-Ba can be less than the thickness of the electron transport functional layer in the upper emission structure EU-Ta, and therefore, the increase and overshoot of the driving voltage can be suppressed, thereby facilitating low power consumption and improved driving life. Accordingly, the light-emitting element ED-a can exhibit excellent luminous efficiency and long life characteristics, and the display device including the light-emitting element ED-a can exhibit excellent display quality and long life characteristics.

[0161] The first upper functional layer UFL-Ba, the second upper functional layer UFL-Ta, and the n-type charge generation layer nCGL may each include at least one sub-functional layer, and three or more layers selected from the sub-functional layers included in the first upper functional layer UFL-Ba, the second upper functional layer UFL-Ta, and the n-type charge generation layer nCGL may each independently include an electron transport material containing a monocyclic 6-membered heteroaryl group including N as a ring atom. For example, in Figure 5 In the light-emitting element ED-a described in

[15] , three or more layers selected from the n-type charge generation layer nCGL and the electron transport sub-functional layers EFL1-B, EFL2-B, EFL3-B, EFL1-T, EFL2-T, and EFL3-T, which perform an electron transport function, may each independently include at least one monocyclic 6-membered heteroaryl group including nitrogen as a ring atom. For example, the monocyclic 6-membered heteroaryl group including nitrogen as a ring atom may be pyridine, pyrimidine, or triazine.

[0162] In an embodiment, at least one of the first to third upper subfunctional layers EFL1-B, EFL2-B and EFL3-B, the fourth to sixth upper subfunctional layers EFL1-T, EFL2-T and EFL3-T, and the n-type charge generation layer nCGL serving as electron transport subfunctional layers may each independently include an electron transport material comprising a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms. In an embodiment, among the sub-functional layers included in the first upper functional layer UFL-Ba, the second upper functional layer UFL-Ta and the n-type charge generation layer nCGL, three or more sub-functional layers selected therefrom may each independently include an electron transport material, which electron transport material includes at least one monocyclic 6-membered heteroaryl group including N as a ring-forming atom; and among the three or more sub-functional layers selected, the electron transport material included in at least one sub-functional layer may include: a monocyclic 6-membered heteroaryl group including N as a ring-forming atom; and a condensed ring group including 8 or more ring-forming carbon atoms.

[0163] In an embodiment, at least one electron transport material included in the electron transport sub-functional layer may be a compound including the following two: a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms. In an embodiment, the condensed ring group may be naphthyl, anthracenyl, fluorenyl, phenanthrenyl, spirobifluorenyl, fluoranthenyl, 1,2-triphenylenyl, quinolyl, quinazolinyl, phenanthrolinyl, triphenylene, carbazolyl, oxaspirobifluorenyl, thiaspirobifluorenyl, pyrenyl, dibenzofuranyl or dibenzothiophenyl. However, the embodiment is not limited thereto.

[0164] In an embodiment, Figure 4 and Figure 5In the light-emitting elements ED and ED-a respectively illustrated in

[0045] , the electron transport material included in at least one of the first upper functional layers UFL-B and UFL-Ba, the second upper functional layers UFL-T and UFL-Ta, and the n-type charge generation layer nCGL may each independently be a compound selected from compound group 1. The compounds listed in compound group 1 may each contain a monocyclic 6-membered heteroaryl group including N as a ring atom. In compound group 1, compounds 13 to 36 and compounds 38 to 58 may each contain a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms.

[0165] [Compound Group 1]

[0166]

[0167]

[0168]

[0169]

[0170] In an embodiment, three or more layers selected from the emission structures EU-B, EU-Ba, EU-T and EU-Ta and the sub-functional layers included in the upper functional layers UFL-B, UFL-Ba, UFL-T and UFL-Ta included in the n-type charge generation layer nCGL may each independently include an electron transport material selected from compound group 1. In an embodiment, at least one layer among the three or more sub-functional layers included in the selected emission structures EU-B, EU-Ba, EU-T and EU-Ta and the upper functional layers UFL-B, UFL-Ba, UFL-T and UFL-Ta included in the n-type charge generation layer nCGL may each independently include at least one electron transport material selected from compounds 13 to 58 in compound group 1.

[0171] In an embodiment, all sub-functional layers included in the upper functional layers UFL-B, UFL-Ba, UFL-T and UFL-Ta included in the emission structures EU-B, EU-Ba, EU-T and EU-Ta and the n-type charge generation layer nCGL may each independently include an electron transport material, which contains a monocyclic 6-membered heteroaryl group including N as a ring atom.

[0172] The light-emitting elements ED and ED-a can each satisfy the thickness relationship of the electron transport functional layer according to Expression 1 as described above; and three or more of the electron transport sub-functional layers can each independently include an electron transport material, which contains a monocyclic 6-membered heteroaryl group including N as a ring atom, and thus the light-emitting elements ED and ED-a can exhibit excellent luminous efficiency and long life characteristics.

[0173] In addition to the electron transport material of compound group 1, the light-emitting elements ED and ED-a may include a conventional electron transport material in at least one of the upper functional layers UFL-B, UFL-Ba, UFL-T, and UFL-Ta, and the n-type charge generation layer nCGL. In embodiments, among the sub-functional layers included in the first upper functional layers UFL-B and UFL-Ba, and the second upper functional layers UFL-T and UFL-Ta, the remaining sub-functional layers that do not include the electron transport material of compound group 1 may include a conventional electron transport material. In embodiments, the sub-functional layers that include the electron transport material of compound group 1, included in the first upper functional layers UFL-B and UFL-Ba, and the second upper functional layers UFL-T and UFL-Ta, may further include a conventional electron transport material.

[0174] For example, in addition to the electron transport material of compound group 1, the first upper functional layers UFL-B and UFL-Ba and the second upper functional layers UFL-T and UFL-Ta may each independently further include an anthracene compound. However, the embodiment is not limited thereto, and the upper functional layers UFL-B and UFL-T may include, for example, tris(8-hydroxyquinoline)aluminum (Alq3), 1,3,5-tris[(3-pyridyl)-phenyl-3-yl]benzene, 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, 2-(4-(N-phenylbenzimidazol-1-yl)phenyl)-9,10-dinaphthothracene, 1,3,5-tris(1-phenyl-1H-benzo[d]imidazole-2 -yl)benzene (TPBi), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalene-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole ( tBu-PBD), bis(2-methyl-8-hydroxyquinolinolato-N1,O8)-(1,1'-biphenyl-4-hydroxy)aluminum (BAlq), bis(benzoquinolinolato-10-hydroxy)beryllium (Bebq2), 9,10-di(naphthalene-2-yl)anthracene (ADN), 1,3-bis[3,5-di(pyridin-3-yl)phenyl]benzene (BmPyPhB), or a mixture thereof.

[0175] In an embodiment, the first upper functional layers UFL-B and UFL-Ba and the second upper functional layers UFL-T and UFL-Ta may each independently include: a metal halide (e.g., LiF, NaCl, CsF, RbCl, RbI, CuI, and KI); a lanthanide (e.g., Yb); or a co-deposited material of a metal halide and a lanthanide. For example, the first upper functional layers UFL-B and UFL-Ba and the second upper functional layers UFL-T and UFL-Ta may include KI:Yb, RbI:Yb, LiF:Yb, etc. as the co-deposited material. The first upper functional layers UFL-B and UFL-Ba and the second upper functional layers UFL-T and UFL-Ta may include a metal oxide (e.g., Li2O and BaO) or 8-hydroxyquinoline lithium (Liq), etc., but the embodiment is not limited thereto. In an embodiment, the first upper functional layers UFL-B and UFL-Ba and the second upper functional layers UFL-T and UFL-Ta may include a mixture of an electron transport material and an insulating organic metal salt. The insulating organic metal salt may be a material having an energy band gap equal to or greater than about 4 eV. For example, the insulating organic metal salt may include metal acetate, metal benzoate, metal acetoacetate, metal acetylacetonate, or metal stearate.

[0176] In addition to the above materials, the first upper functional layers UFL-B and UFL-Ba and the second upper functional layers UFL-T and UFL-Ta may further include at least one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), diphenyl(4-(triphenylsilyl)phenyl)phosphine oxide (TSPO1) and 4,7-diphenyl-1,10-phenanthroline (Bphen), but the embodiment is not limited thereto.

[0177] The lower functional layers LFL-B, LFL-Ba, LFL-T, and LFL-Ta included in the emission structures EU-B, EU-Ba, EU-T, and EU-Ta may each perform a hole transport function. The lower functional layers LFL-B, LFL-Ba, LFL-T, and LFL-Ta may each independently have a structure consisting of a single layer (composed of a single material), a structure consisting of a single layer comprising different materials, or a structure comprising a plurality of layers comprising different materials.

[0178] In an embodiment, the first lower functional layers LFL-B and LFL-Ba and the second lower functional layers LFL-T and LFL-Ta may each independently include a hole transport material in the prior art. For example, the first lower functional layers LFL-B and LFL-Ba and the second lower functional layers LFL-T and LFL-Ta may each independently further include a phthalocyanine compound (e.g., copper phthalocyanine), N 1 ,N 1’ -([1,1'-biphenyl]-4,4'-diyl)bis(N 1 -phenyl-N 4 ,N 4 -dimethylphenyl-1,4-diamine) (DNTPD), 4,4',4"-[tris(3-methylphenyl)phenylamino]triphenylamine (m-MTDATA), 4,4',4"-tris(N,N-diphenylamino)triphenylamine (TDATA), 4,4',4"-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (1-TNATA), 4,4',4"-tris[N-(2-naphthyl)-N-phenylamino]triphenylamine (2-TNATA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), poly Aniline / dodecylbenzenesulfonic acid (PANI / DBSA), polyaniline / camphorsulfonic acid (PANI / CSA), polyaniline / poly(4-styrenesulfonate) (PANI / PSS), N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB (or NPD, α-NPD)), triphenylamine-containing polyether ketone (TPAPEK), 4-isopropyl-4'-methyldiphenyliodonium [tetrakis(pentafluorophenyl)borate], dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN), etc.

[0179] The first lower functional layers LFL-B and LFL-Ba and the second lower functional layers LFL-T and LFL-Ta may each independently include carbazole derivatives (e.g., N-phenylcarbazole and polyvinylcarbazole), fluorene derivatives, triphenylamine derivatives (e.g., 4,4',4"-tris(carbazole-9-yl)triphenylamine (TCTA), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), N,N'-di(naphthalene-1-yl)-N,N'-diphenyl-benzidine (NPB), 4,4'-cyclohexylenebis[N,N-bis(4-methylphenyl)aniline] (TAPC), 4,4'-bis[N,N'-(3-tolyl)amino]-3,3'-dimethylbiphenyl (HMTPD) or 1,3-bis(N-carbazolyl)benzene (mCP)), etc.

[0180] In an embodiment, the first lower functional layers LFL-B and LFL-Ba and the second lower functional layers LFL-T and LFL-Ta may each independently include 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi), 9-phenyl-9H-3,9'-dicarbazole (CCP) or 1,3-bis(1,8-dimethyl-9H-carbazole-9-yl)benzene (mDCP) and the like.

[0181] In addition to the above materials, the first lower functional layers LFL-B and LFL-Ba, and the second lower functional layers LFL-T and LFL-Ta, may each independently further include a charge generation material to improve conductivity. The charge generation material may be uniformly or non-uniformly dispersed throughout the first lower functional layers LFL-B and LFL-Ba, and the second lower functional layers LFL-T and LFL-Ta. The charge generation material may be, for example, a p-dopant. The p-dopant may include at least one of a metal halide, a quinone derivative, a metal oxide, and a cyano compound, but embodiments are not limited thereto. For example, the p-dopant may include a metal halide (e.g., CuI or RbI), a quinone derivative (e.g., tetracyanoquinodimethane (TCNQ) or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ)), a metal oxide (e.g., tungsten oxide or molybdenum oxide), a cyano group-containing compound (e.g., dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) or 4-[[2,3-bis[cyano-(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropylidene]-cyanomethyl]-2,3,5,6-tetrafluorobenzonitrile (NDP9)), etc., but the embodiment is not limited thereto.

[0182] In respectively Figure 4 and Figure 5 In the light-emitting elements ED and ED-a explained in the accompanying drawings, the emission layers EML-B and EML-T are respectively arranged on the lower functional layers LFL-B, LFL-Ba, LFL-T and LFL-Ta. The emission layers EML-B and EML-T may each independently have a structure consisting of a single layer (composed of a single material), a structure consisting of a single layer including different materials, or a structure including multiple layers including different materials. The emission layers EML-B and EML-T may each independently include a fluorescent light-emitting material or a phosphorescent light-emitting material. The emission layers EML-B and EML-T may each independently include a host material. In an embodiment, at least one of the emission layers EML-B and EML-T may each independently include a hole transport host and an electron transport host.

[0183] In the light-emitting elements ED and ED-a, the emission layers EML-B and EML-T may each independently include an anthracene derivative, a pyrene derivative, a fluoranthene derivative, a 1,2-triphenylene derivative, a dihydrobenzanthracene derivative, or a triphenylene derivative. For example, the emission layers EML-B and EML-T may each independently include an anthracene derivative or a pyrene derivative. However, the embodiment is not limited thereto, and the emission layers EML-B and EML-T may include a light-emitting material of the related art.

[0184] The emission layers EML-B and EML-T may each independently include a host material and a dopant material. In the light-emitting elements ED and ED-a, the emission layers EML-B and EML-T may each independently include a host material and a dopant material of the prior art. The emission layers EML-B and EML-T may each independently include an anthracene derivative, a pyrene derivative, a fluoranthene derivative, a 1,2-triphenylene derivative, a dihydrobenzanthracene derivative, or a triphenylene derivative as a host material. The emission layers EML-B and EML-T may each independently further include a host material of the prior art. For example, the emission layers EML-B and EML-T may each independently include at least one of bis[2-(diphenylphosphino)phenyl]ether oxide (DPEPO), 4,4'-bis(carbazol-9-yl)biphenyl (CBP), 1,3-bis(N-carbazol-1-yl)benzene (mCP), 2,8-bis(diphenylphosphino)dibenzo[b,d]furan (PPF), 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), and 1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi) as a host material. However, embodiments are not limited thereto. For example, tris(8-hydroxyquinoline) Aluminum (Alq3), poly (N-vinylcarbazole) (PVK), 9,10-di(naphthalene-2-yl)anthracene (ADN), 2-tert-butyl-9,10-di(naphthalene-2-yl)anthracene (TBADN), distyryl aromatic hydrocarbon (DSA), 4,4'-bis(9-carbazolyl)-2,2'-dimethyl-biphenyl (CDBP), 2-methyl-9,10-bis(naphthalene-2-yl)anthracene (MADN), hexaphenylcyclotriphosphazene (CP1), 1,4-bis(triphenylsilyl)benzene (UGH2), hexaphenylcyclotrisiloxane (DPSiO3), octaphenylcyclotetrasiloxane (DPSiO4), etc. can be used as host materials.

[0185] In an embodiment, the emission layers EML-B and EML-T may each independently further include a styryl derivative (e.g., 1,4-bis[2-(3-N-ethylcarbazolyl)vinyl]benzene (BCzVB), 4-(di-p-tolylamino)-4'-[(di-p-tolylamino)styryl]stilbene (DPAVB), N-(4-((E)-2-(6-((E)-4-(diphenylamino)styryl)naphthalene-2-yl)ethyl As dopant materials in the prior art, there are used 2,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl (DPAVBi)), perylene or its derivatives (e.g., 2,5,8,11-tetra-tert-butylperylene (TBP)), pyrene or its derivatives (e.g., 1,1'-dipyrene, 1,4-dipyrenylbenzene, 1,4-bis(N,N-diphenylamino)pyrene), etc.

[0186] The emission layers EML-B and EML-T may each independently further include a prior art phosphorescent dopant material. For example, a metal complex including iridium (Ir), platinum (Pt), osmium (Os), gold (Au), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), or thulium (Tm) may be used as a phosphorescent dopant. For example, bis(4,6-difluorophenylpyridyl-N,C2') picolinyl iridium (III) (FIrpic), bis(2,4-difluorophenylpyridyl)-tetrakis(1-pyrazolyl) iridium (III) borate (FIr6), or platinum octaethylporphyrin (PtOEP) may be used as a phosphorescent dopant. However, embodiments are not limited thereto.

[0187] In an embodiment, the emission layers EML-B and EML-T may each independently include a quantum dot material.

[0188] In the light-emitting elements ED and ED-a, the first emission layer EML-B of the lower emission structures EU-B and EU-Ba and the second emission layer EML-T of the upper emission structures EU-T and EU-Ta may overlap with each other in the thickness direction and may emit light in the same wavelength region. The first emission layer EML-B and the second emission layer EML-T may include the same light-emitting material. However, the embodiment is not limited thereto. Figure 4 and Figure 5 , the first emission layer EML-B and the second emission layer EML-T are each explained as a single layer, but the embodiment is not limited thereto, and the first emission layer EML-B and the second emission layer EML-T may each independently include a plurality of sub-emission layers.

[0189] In the light-emitting elements ED and ED-a, the charge generation layer CGL may include an n-type arylamine material or a p-type metal oxide. For example, the charge generation layer CGL may include a charge generation compound composed of an arylamine organic compound, a metal carbonate, a metal fluoride, a metal oxide, or a mixture thereof.

[0190] For example, the n-type charge generation layer nCGL may include 4,7-diphenyl-1,10-phenanthroline (Bphen), α-NPD, 2-TNATA, TDATA, MTDATA, spiro-TAD, or spiro-NPB. For example, the p-type charge generation layer pCGL may include a metal such as cesium (Cs), molybdenum (Mo), vanadium (V), titanium (Ti), tungsten (W), barium (Ba), or lithium (Li). Examples of metal oxides, metal carbonates, or metal fluorides may include Re2O7, MoO3, V2O5, WO3, TiO2, Cs2CO3, BaF2, LiF, or CsF.

[0191] Figure 6 The light emitting element ED-1 described in Figure 4 and Figure 5 The light emitting elements ED and ED-a shown in FIG. 5 may differ at least in the number of stacked emission structures. Figure 6 The components of the light emitting element ED-1 explained in the above can be used with reference to the above explained Figure 4 and Figure 5 The components of the light-emitting elements ED and ED-a are the same as described.

[0192] See also Figure 6 , the light emitting element ED-1 may include (n-1) charge generation layers CGL1, CGL2, ... and CGL(n-1) and n emission structures EU1, EU2, ... and EUn provided between the first electrode AE ​​and the second electrode CE. Among the n emission structures EU1, EU2, ... and EUn, the first emission structure EU1 may correspond to the respective reference Figure 4 The lower emission structure EU-B and Figure 5 The lower emission structure EU-Ba described, and the nth emission structure EUn may correspond to the respective reference Figure 4 The upper emission structure EU-T and Figure 5 Described upper emission structure EU-Ta.

[0193] According to the embodiment, Figure 6 The light-emitting element ED-1 explained in the above may satisfy Expression 1:

[0194] [Expression 1]

[0195] 50nm≥d TOP >d LOW >15nm.

[0196] In Expression 1, d LOW may be the sum d1 of the thickness of the upper functional layer UFL-1 included in the first emission structure EU1 (which is the lower emission structure adjacent to the first electrode AE ​​among the n emission structures) and the thickness of the n-type charge generation layer nCGL1 directly disposed on the first emission structure EU1; and d TOP The thickness d may be the thickness of the upper functional layer UFL-n included in the n-th emission structure EUn (which is the upper emission structure adjacent to the second electrode CE among the n emission structures). n .

[0197] therefore, Figure 6 The light-emitting element ED-1 explained in the embodiment may also satisfy the thickness relationship of Expression 1, wherein the light-emitting element ED-1 includes n emission structures, so that the thickness of the nth upper functional layer UFL-n including the nth electron transport layer ETL-n and the nth electron transport auxiliary layer BFL-n (wherein the nth upper functional layer UFL-n performs an electron transport function in the upper emission structure EUn and is arranged to be adjacent to the second electrode CE) may be greater than the sum of the thickness of the n-type charge generation layer nCGL1 and the thickness of the first upper functional layer UFL-1 including the first electron transport layer ETL-1 and the first electron transport auxiliary layer BFL-1, wherein the first upper functional layer UFL-1 performs an electron transport function in the lower emission structure EU1 and is arranged to be adjacent to the first electrode AE.

[0198] Among the (n-1) charge generation layers CGL1, CGL2, ..., and CGL(n-1) and the n emission structures EU1, EU2, ..., and EUn disposed between the first electrode AE ​​and the second electrode CE, the thickness d of the electron transport functional layer of the nth emission structure EUn adjacent to the second electrode CE is n The thickness of the upper functional layer UFL-2 of the second emission structure EU2 and the thickness of the n-type charge generation layer nCGL2 of the second charge generation layer CGL2 may be greater than about 15 nm and less than the thickness d2 of the upper functional layer UFL-n included in the n emission structure EUn. n .

[0199] Accordingly, when the thickness relationship of Expression 1 is satisfied, the light-emitting element ED-1 can exhibit excellent luminous efficiency and long life characteristics, and a display device including the light-emitting element ED-1 can exhibit excellent display quality and long life characteristics.

[0200] Among the upper functional layers UFL-1, UFL-2, ... and UFL-n included in the n emission structures EU1, EU2, ... and EUn and the n-type charge generation layers nCGL1, nCGL2, ... and nCGL(n-1) in the (n-1) charge generation layers CGL1, CGL2, ... and CGL(n-1), three or more layers selected therefrom may each independently include an electron transport material comprising a monocyclic 6-membered heteroaryl group including N as a ring-forming atom. In an embodiment, at least one layer among the three or more selected layers may include an electron transport material comprising a monocyclic 6-membered heteroaryl group including N as a ring-forming atom and a condensed ring group including 8 or more ring-forming carbon atoms.

[0201] The light-emitting element ED-1 may satisfy the thickness relationship of Expression 1 as described above and may include the electron transport material as described above, and thus may exhibit characteristics of high luminous efficiency and long life.

[0202] Figure 7 : is a schematic cross-sectional view of a portion of a display panel according to an embodiment. As an example, Figure 7 It is explained that the first to third light emitting elements ED-R, ED-G and ED-B of the display layer EDL each have Figure 4 However, the embodiment is not limited thereto, and any light emitting element having a tandem structure satisfying the thickness relationship of Expression 1 as for the electron transport function layer as described above can also be used in the display layer EDL.

[0203] According to an embodiment, the display layer EDL may include a first electrode AE, a hole injection layer HIL, a lower emission structure EU-B, a charge generation layer CGL, an upper emission structure EU-T, an electron injection layer EIL, a second electrode CE, and a capping layer CPL. The lower emission structure EU-B may include a first lower functional layer LFL-B, a first emission layer EML-B, and a first upper functional layer UFL-B. The upper emission structure EU-T may include a second lower functional layer LFL-T, a second emission layer EML-T, and a second upper functional layer UFL-T. The charge generation layer CGL may include an n-type charge generation layer nCGL and a p-type charge generation layer pCGL.

[0204] The first electrode AE ​​may be separated and provided in each of the first to third light-emitting elements ED-R, ED-G, and ED-B. In an embodiment, the hole injection layer HIL, the first lower functional layer LFL-B, the first upper functional layer UFL-B, the charge generation layer CGL, the second upper functional layer UFL-T, the electron injection layer EIL, the second electrode CE, and the capping layer CPL may each be provided as a common layer throughout the first to third light-emitting elements ED-R, ED-G, and ED-B. However, the embodiment is not limited thereto.

[0205] In an embodiment, the first light-emitting element ED-R may include a first sub-red light-emitting layer REML-S1 as a first emission layer EML-B, a second sub-red light-emitting layer REML-S2 as a second emission layer EML-T, and a red light emission auxiliary layer AEL-R as a second lower functional layer LFL-T.

[0206] In an embodiment, the second light-emitting element ED-G may include a first green light-emitting layer GEML-S1 as a first emission layer EML-B, a second green light-emitting layer GEML-S2 as a second emission layer EML-T, and a green light-emitting auxiliary layer AEL-G as a second lower functional layer LFL-T. In an embodiment, the third light-emitting element ED-B may include a first blue light-emitting layer BEML-S1 as a first emission layer EML-B, a second blue light-emitting layer BEML-S2 as a second emission layer EML-T, and a blue light-emitting auxiliary layer AEL-B as a second lower functional layer LFL-T.

[0207] The red light emitting auxiliary layer AEL-R, the green light emitting auxiliary layer AEL-G, and the blue light emitting auxiliary layer AEL-B may be separated and respectively disposed in the first to third light emitting elements ED-R, ED-G, and ED-B. In the case where the emission auxiliary layer is included as the second lower functional layer LFL-T, the thickness of the second lower functional layer LFL-T may be different depending on the wavelength of light emitted from the first to third light emitting elements ED-R, ED-G, and ED-B, respectively. In an embodiment, the thickness t of the red light emitting auxiliary layer AEL-R of the first light emitting element ED-R emitting red light is t SR The thickness t of the green light emitting auxiliary layer AEL-G of the second light emitting element ED-G emitting green light may be greater than SG In an embodiment, the thickness t of the green light emitting auxiliary layer AEL-G of the second light emitting element ED-G emitting green light is SG It can be greater than the thickness t of the blue light emitting auxiliary layer AEL-B of the third light emitting element ED-B emitting blue light. SB .

[0208] exist Figure 7 In the display layer EDL explained in , according to Expression 1 as explained above, the thickness of the second upper functional layer UFL-T may be greater than the sum of the thickness of the first upper functional layer UFL-B and the thickness of the n-type charge generation layer nCGL, wherein the thickness of the second upper functional layer UFL-T may be equal to or less than about 50 nm. Figure 7In the display layer EDL illustrated in FIG, the sum of the thickness of the first upper functional layer UFL-B and the thickness of the n-type charge generation layer nCGL may be greater than about 15 nm according to Expression 1 as explained above. By satisfying the thickness relationship of Expression 1, the first to third light-emitting elements ED-R, ED-G, and ED-B can exhibit characteristics of high luminous efficiency and long lifespan, so that a display device including the first to third light-emitting elements ED-R, ED-G, and ED-B can exhibit characteristics of improved display quality due to excellent luminous efficiency and improved reliability due to long lifespan.

[0209] Hereinafter, evaluation results of characteristics of the light emitting element according to the embodiment will be described with reference to Examples and Comparative Examples.The Examples described below are provided only for understanding the present disclosure, and the scope thereof is not limited thereto.

[0210] <Manufacturing of Light-Emitting Element>

[0211] The light-emitting elements according to Examples 1 to 4 and Comparative Examples 1 to 5 were manufactured as series light-emitting elements by forming a first electrode, a lower emission structure, a charge generation layer, an upper emission structure, a second electrode, and a capping layer on a glass substrate. Figure 4 The structure of the light emitting element explained in the embodiment is used to manufacture each series light emitting element according to the embodiment and the comparative example. Specifically, the embodiment and the comparative example also apply Figure 4 The light-emitting elements of Examples 1 to 4 and Comparative Examples 1 to 5 were evaluated by evaluating the blue light-emitting structures included therein.

[0212] Each light emitting element according to the embodiment and the comparative example was manufactured by the following method. ) is deposited on the first electrode of the present invention to form a hole injection layer. A lower emission structure is formed on the hole injection layer. A first lower functional layer is formed by depositing only about 20 nm of compound HT1 on the hole injection layer. A first emission layer with a thickness of about 20 nm is formed by co-depositing compound BH and compound BD on the first lower functional layer. Compound BH and compound BD are co-deposited at a weight ratio of about 97:3. A first electron transport auxiliary layer is formed by depositing about 5 nm of compound BF1 (i.e., compound 28) on the first emission layer, and a first electron transport layer is formed by depositing about 10 nm of compound ET1 (i.e., compound 21) on the first electron transport auxiliary layer.

[0213] An n-type charge generation layer and a p-type charge generation layer were formed on the first electron transport layer as charge generation layers by depositing about 10 nm of 4,7-diphenyl-1,10-phenanthroline (Bphen) doped with Li (about 2 wt%) and about 5 nm of compound HT1 doped with F4-TCNQ (about 5 wt%), respectively.

[0214] An upper emission structure is formed on the charge generation layer. A second lower functional layer is formed by depositing about 40 nm of compound HT1 on the charge generation layer and about 10 nm of compound HT2 thereon. A second emission layer is formed on the second lower functional layer using the same materials and structures as described above for the first emission layer of the lower emission structure. A second electron transport auxiliary layer is formed by depositing about 5 nm of compound BF2 (i.e., compound 43) on the second emission layer, and a second electron transport layer as a common layer is formed by depositing about 30 nm of compound ET2 (i.e., compound 34).

[0215] On the upper emission structure, a Mg:Ag (about 9:1 by weight) layer with a thickness of about A second electrode with a thickness of 100 nm was formed. A capping layer as a common layer was formed by depositing a compound CP5 to a thickness of about 60 nm on the second electrode, and thus a light-emitting element was manufactured. Each layer was formed by a vacuum deposition method.

[0216] Materials used to produce each light-emitting element of Examples and Comparative Examples are shown below.

[0217]

[0218] The materials used for each electron transport functional layer (i.e., the first upper functional layer including the first electron transport auxiliary layer and the first electron transport layer, the second upper functional layer including the second electron transport auxiliary layer and the second electron transport layer, and the n-type charge generation layer) according to Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Table 1.

[0219] Table 1

[0220]

[0221]

[0222] <Evaluation of Light-Emitting Element>

[0223] Table 2 shows the thickness of each electron transport functional layer (i.e., a first upper functional layer including a first electron transport auxiliary layer and a first electron transport layer, a second upper functional layer including a second electron transport auxiliary layer and a second electron transport layer, and an n-type charge generation layer) in the embodiment and the comparative example, as well as the resulting luminous efficiency and life characteristics of the embodiment and the comparative example. The luminous efficiency and life characteristics are shown as relative values ​​when the luminous efficiency and life of Comparative Example 1 are set to 100%.

[0224] The luminous efficiency and lifetime shown in Table 2 were each measured by using a Keithley SMU 236 and a luminance meter PR650 Spectroscan source measurement unit (PhotoResearch Inc.), and the results are shown as relative values. The lifetime in Table 2 is the T95 lifetime, which is the lifetime of the luminous efficiency ... 2 The time required for the brightness to decrease to about 95% was measured under the condition of the current density.

[0225] Table 2

[0226]

[0227]

[0228] Referring to the results in Table 2, each of the embodiments satisfies the thickness relationship in which the sum of the thickness of the second electron transport auxiliary layer and the thickness of the second electron transport layer is greater than the sum of the thickness of the first electron transport auxiliary layer, the thickness of the first electron transport layer, and the thickness of the n-type charge generation layer, so that the sum of the thickness of the first electron transport auxiliary layer, the thickness of the first electron transport layer, and the thickness of the n-type charge generation layer is greater than about 15 nm, and the sum of the thickness of the second electron transport auxiliary layer and the thickness of the second electron transport layer is equal to or less than about 50 nm, so that each of the embodiments exhibits excellent luminous efficiency and long life characteristics compared to Comparative Examples 1 to 3 that do not satisfy this thickness relationship. Compared to Comparative Example 5 in which the sum of the thickness of the electron transport functional layer included in the upper emission structure is equal to the sum of the thickness of the electron transport functional layer included in the lower emission structure and the thickness of the n-type charge generation layer, Examples 1 to 4 also exhibit excellent luminous efficiency and long life characteristics.

[0229] The embodiment is further characterized in that three or more layers selected from among the first electron transport auxiliary layer, the first electron transport layer, the n-type charge generation layer, the second electron transport auxiliary layer and the second electron transport layer include electron transport materials (for example, BF1, ET1, BF2 and ET2 as described above), and compared with Comparative Example 4 in which only two layers include such electron transport materials, the embodiment exhibits excellent luminous efficiency and long life characteristics.

[0230] In the light-emitting element according to the embodiment, the light-emitting element having a stacked structure can be optimized to meet the following thickness relationship: the sum of the thickness of the electron transport functional layer included in the upper emission structure is greater than the sum of the thickness of the electron transport functional layer included in the lower emission structure and the thickness of the n-type charge generation layer, the sum of the thickness of the electron transport functional layer included in the lower emission structure and the thickness of the n-type charge generation layer is greater than about 15 nm, and the sum of the thickness of the electron transport functional layer included in the upper emission structure is equal to or less than about 50 nm, and thus can exhibit excellent luminous efficiency and long life characteristics. In the light-emitting element according to the embodiment, among the electron transport functional layer included in the upper emission structure and the electron transport functional layer included in the lower emission structure, three or more electron transport functional layers may include an electron transport material containing a monocyclic 6-membered heteroaryl group including nitrogen as a ring atom, and thus can exhibit high luminous efficiency and long life characteristics. A display device according to the embodiment including at least one light-emitting element having a stacked structure as described above can exhibit excellent luminous efficiency, display quality, and long life characteristics.

[0231] According to the embodiment, the light-emitting element may include a plurality of emission structures, and among the plurality of emission structures, the relationship between the thickness of the electron transport functional layer provided in the upper emission structure and the thickness of the electron transport functional layer provided in the lower emission structure may be optimized, and thus, the characteristics of improved luminous efficiency and excellent lifespan may be exhibited.

[0232] In the display device according to the embodiment, the thickness relationship of the electron transport functional layers in the plurality of emission structures may be optimized, and thus, characteristics of excellent display quality and improved lifespan may be exhibited.

[0233] Embodiments have been disclosed herein, and although terms are employed, they are used and interpreted in a generic and descriptive sense only and not for purposes of limitation. In some cases, as will be apparent to one of ordinary skill in the art, features, characteristics, and / or elements described in connection with an embodiment may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless specifically indicated otherwise. Accordingly, those of ordinary skill in the art will understand that various changes in form and details may be made without departing from the spirit and scope of the present disclosure as set forth in the claims.

Claims

1. A light-emitting element, comprising: a first electrode; a second electrode, facing the first electrode; a lower emission structure, disposed between the first electrode and the second electrode, the lower emission structure comprising a first lower functional layer, a first emission layer, and a first upper functional layer stacked in sequence; an upper emission structure, disposed on the lower emission structure, the upper emission structure comprising a second lower functional layer, a second emission layer, and a second upper functional layer stacked in sequence; as well as A charge generation layer is provided between the lower emission structure and the upper emission structure, wherein the charge generation layer includes an n-type charge generation layer and a p-type charge generation layer. The light emitting element satisfies Expression 1: [Expression 1] 50nm≥d TOP >d LOW >15nm, In Expression 1, d LOW is the sum of the thickness of the first upper functional layer and the thickness of the n-type charge generation layer, and d TOP is the thickness of the second upper functional layer.

2. The light-emitting element according to claim 1, wherein The first upper functional layer, the second upper functional layer, and the n-type charge generation layer each include an electron transport material, and The first lower functional layer and the second lower functional layer each include a hole transport material.

3. The light-emitting element according to claim 1, wherein The first upper functional layer comprises: a first electron transport layer disposed directly below the n-type charge generation layer; and a first electron transport auxiliary layer, disposed directly below the first electron transport layer, and The second upper functional layer comprises: a second electron transport auxiliary layer, directly disposed on the second emission layer; and The second electron transport layer is directly disposed on the second electron transport auxiliary layer.

4. The light-emitting element according to claim 3, wherein three or more layers selected from the first electron transport layer, the first electron transport auxiliary layer, the n-type charge generation layer, the second electron transport auxiliary layer and the second electron transport layer each independently include an electron transport material, and the electron transport material contains a monocyclic 6-membered heteroaryl group including N as a ring atom. 5 . The light-emitting element according to claim 4 , wherein the electron transport material included in at least one layer among the selected three or more layers comprises a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms.

6. The light-emitting element according to claim 5, wherein the fused ring group is a naphthyl, anthracenyl, fluorenyl, phenanthrenyl, spirobifluorenyl, fluoranthenyl, 1,2-triphenylenyl, quinolyl, quinazolinyl, phenanthrolinyl, triphenylene, carbazolyl, oxaspirobifluorenyl, thiaspirobifluorenyl, pyrenyl, dibenzofuranyl or dibenzothiophenyl.

7. The light-emitting element according to claim 4, wherein the electron transport material is a compound selected from compound group 1: [Compound Group 1] 8 . The light-emitting element according to claim 1 , wherein the first emission layer and the second emission layer emit light in the same wavelength region.

9. The light-emitting element according to claim 1, wherein At least one of the first upper functional layer and the second upper functional layer each independently includes three or more electron transport functional layers, and The electron transport functional layer is each an electron injection layer, an electron transport layer or a hole blocking layer.

10. The light-emitting element according to claim 1, wherein At least one of the first lower functional layer and the second lower functional layer each independently includes three or more hole transport functional layers, and The hole transport functional layer is each a hole injection layer, a hole transport layer, an electron blocking layer or an emission auxiliary layer.

11. The light-emitting element according to claim 10, further comprising: The capping layer is arranged on the second electrode.

12. A light-emitting element, comprising: a first electrode; a second electrode, facing the first electrode; a plurality of emission structures disposed between the first electrode and the second electrode, each emission structure comprising a lower functional layer, an emission layer, and an upper functional layer stacked in sequence; as well as One or more charge generation layers, each charge generation layer being disposed between adjacent emission structures among the plurality of emission structures, and each charge generation layer comprising an n-type charge generation layer and a p-type charge generation layer, wherein The light emitting element satisfies Expression 1: [Expression 1] 50nm≥d TOP >d LOW >15nm, In Expression 1, d LOW is the sum of the thickness of the upper functional layer of the lower emission structure adjacent to the first electrode and the thickness of the n-type charge generation layer directly disposed on the lower emission structure, and d TOP is the thickness of the upper functional layer of the upper emission structure adjacent to the second electrode.

13. The light-emitting element according to claim 12, wherein The upper functional layer of each emission structure includes an electron transport material, and The lower functional layer of each emission structure includes a hole transport material.

14. The light-emitting element according to claim 12, wherein The upper functional layer of the upper emission structure includes a plurality of upper electron transport functional layers, The upper functional layer of the lower emission structure includes a plurality of lower electron transport functional layers, and Three or more layers selected from the plurality of upper electron transport functional layers, the plurality of lower electron transport functional layers, and the n-type charge generation layer directly disposed on the lower emission structure each independently include an electron transport material containing a monocyclic 6-membered heteroaryl group including N as a ring atom. 15 . The light-emitting element according to claim 14 , wherein the electron transport material included in at least one layer among the selected three or more layers comprises a monocyclic 6-membered heteroaryl group including N as a ring atom and a condensed ring group including 8 or more ring carbon atoms.

16. The light-emitting element according to claim 14, wherein the electron transport material is selected from the compounds in compound group 1: [Compound Group 1] 17. An electronic device comprising a display device, wherein the display device comprises: The red light-emitting area, the green light-emitting area, and the blue light-emitting area are separated from each other in a plan view; a circuit layer, disposed on the base layer; and The display layer is provided on the circuit layer, wherein The display layer includes: A red light emitting element is arranged in the red light emitting area; A green light emitting element is disposed in the green light emitting area; and A blue light emitting element is arranged in the blue light emitting area, The red light-emitting element, the green light-emitting element, and the blue light-emitting element are each the light-emitting element according to any one of claims 1 to 16.

18. The electronic device according to claim 17, wherein the first lower functional layer, the first upper functional layer, the charge generation layer, the second lower functional layer and the second upper functional layer are each provided as a common layer in the red light emitting area, the green light emitting area and the blue light emitting area.

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