Display device

Abstract

A display device with high light efficiency and color purity is provided. The display device includes: a first electrode; a pixel defining layer disposed on the first electrode and having an opening; an organic emission layer disposed on the pixel defining layer, the organic emission layer being electrically connected to the first electrode through the opening; a second electrode disposed on the organic emission layer; a light recycling layer disposed on the second electrode; and a color filter layer disposed on the light recycling layer and including quantum dots, wherein the color filter layer completely overlaps the organic emission layer, and the width direction length of the organic emission layer is longer than the width direction length of the color filter layer.

Description

Technical Field

[0001] A display device capable of displaying an image is disclosed. Background Art

[0002] Currently available display devices include liquid crystal displays (LCDs), plasma display panels (PDPs), organic light emitting diode (OLED) displays, etc. Among these devices, since liquid crystal displays (LCDs) and organic light emitting diode (OLED) displays can be easily made into thin films and have some advantages in terms of low power and low heat release, etc., they can be applied to various display devices such as mobile devices, computer monitors, and televisions (TVs).

[0003] Compared with other display devices, organic light emitting diode (OLED) displays are very thin and flexible, so they are more likely to be applied to flexible display devices (such as rollable, stretchable or foldable devices) and small portable electronic devices (such as smart bracelets, smart watches, etc.).

[0004] On the other hand, recently, in order to improve the color purity of organic light emitting diode (OLED) displays, attempts have been made to provide color filters including quantum dots. Quantum dots are nanocrystalline semiconductor materials having a diameter of less than or equal to about 10 nm that exhibit a quantum confinement effect. Compared with commonly used phosphors, quantum dots produce stronger light in a narrow wavelength region and are therefore effective in improving the color purity of emitted light.

[0005] Quantum dots emit light when excited electrons transition from the conduction band to the valence band, and even in the same material, the wavelength varies depending on the particle size. Since quantum dots emit shorter wavelength light at smaller particle sizes, they can obtain light in a desired wavelength region by adjusting the size.

[0006] However, since quantum dots emit light in all directions, in order to improve light efficiency, it is necessary to drive the light converted by the quantum dots in a specific direction or increase the energy required to drive it. Therefore, even if a color filter including quantum dots is provided in an organic light emitting diode (OLED) display, a method of ensuring both light efficiency and color purity is required. Summary of the invention

[0007] Provided is a display device having improved light efficiency and color purity.

[0008] According to one embodiment, a display device includes: a first electrode; a pixel defining layer, which is arranged on the first electrode and has an opening; an organic emission layer, which is arranged on the pixel defining layer, and is electrically connected to the first electrode through the opening; a second electrode, which is arranged on the organic emission layer; a light recovery layer, which is arranged on the second electrode; and a color filter layer, which is arranged on the light recovery layer and includes quantum dots, wherein the color filter layer completely overlaps with the organic emission layer, and the width direction length of the organic emission layer is longer than the width direction length of the color filter layer.

[0009] A side portion of the pixel defining layer formed by the opening may have an inclined structure, and the organic emission layer may extend to a portion of an upper surface of the pixel defining layer along the inclined structure at the side portion of the pixel defining layer.

[0010] The width of the opening is longer than or equal to the width of the color filter layer.

[0011] At least a portion of the color filter layer may be received in the opening.

[0012] The organic emission layer may emit third light, and the light recycling layer may transmit the third light but may reflect first light and second light different from the third light.

[0013] The first light may be red light, the second light may be green light, and the third light may be blue light.

[0014] The light recycling layer may have a transmittance greater than or equal to about 90% with respect to the third light.

[0015] The light recycling layer may have a transmittance of less than or equal to about 20% with respect to the first light and the second light.

[0016] The light recycling layer may have a thickness in a range from about 0.5 μm to about 5 μm.

[0017] The color filter layer may include: a first color filter layer including first quantum dots that convert the third light into the first light; and a second color filter layer including second quantum dots that convert the third light into the second light.

[0018] The first electrode may be disposed on the substrate, and the display device may further include a transmission layer adjacent to at least one of the first color filter layer and the second color filter layer in a direction parallel to an upper surface of the substrate.

[0019] The transmission layer and / or the color filter layer may include a light scatterer.

[0020] The display device may further include a light blocking member between every adjacent two of the first color filter layer, the second color filter layer, and the transmission layer in a direction parallel to the upper surface of the substrate.

[0021] The light recycling layer may overlap at least one of the first color filter layer and the second color filter layer, respectively.

[0022] The second electrode and the light recycling layer may directly contact each other, and at least a portion of an upper surface of the second electrode may include a concavo-convex structure.

[0023] The second electrode and the light recycling layer may directly contact each other, and at least a portion of an upper surface and / or a lower surface of the light recycling layer may include a concavo-convex structure.

[0024] The display device may further include a third light blocking layer disposed on the color filter layer and overlapping at least one of the first color filter layer and the second color filter layer.

[0025] The quantum dots may include a II-VI compound not containing Cd, a III-V compound, a IV-VI compound, a Group IV element or compound, a I-III-VI compound, a I-II-IV-VI compound not containing Cd, or a combination thereof.

[0026] Quantum dots can have a core-shell structure.

[0027] A display device having improved light efficiency and color purity can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a cross-sectional view showing a display device according to an embodiment.

[0029] Figure 2 FIG. 1 is a schematic diagram schematically illustrating a light conversion process of a color filter layer in one pixel of a display device according to an embodiment.

[0030] Figure 3 is a diagram schematically illustrating a light conversion process of a color filter layer when the requirements of a display device according to an embodiment are not met.

[0031] Figure 4 is a graph showing wavelength-dependent light transmittance variation of a light recycling layer according to viewing angle variation.

[0032] Figures 5 to 8 are cross-sectional views showing various exemplary modifications in which a concavo-convex structure is applied to a second electrode and / or a light recycling layer of a display device according to an embodiment.

[0033] Fig. 9 is a cross-sectional view illustrating a display device further including a third light blocking layer according to an exemplary variation. DETAILED DESCRIPTION

[0034] Hereinafter, exemplary embodiments of the present invention will be described in detail so that those skilled in the art will understand the exemplary embodiments of the present invention. However, the present disclosure may be implemented in many different forms and is not to be construed as limited to the exemplary embodiments set forth herein.

[0035] In the accompanying drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. Throughout the specification, the same reference numerals refer to the same elements. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element, or there can also be intervening elements. Conversely, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0036] As used herein, a "group" may refer to a group of the periodic table of elements.

[0037] As used herein, “Group II” may refer to Group IIA and Group IIB, and examples of Group II metals may be Cd, Zn, Hg, and Mg, without being limited thereto.

[0038] As used herein, examples of “Group II metals” may refer to Group II metals such as Zn, Cd, Hg, Mg, and the like.

[0039] As used herein, “Group III” may refer to Group IIIA and Group IIIB, and examples of Group III metals may be Al, In, Ga, and Tl, without being limited thereto.

[0040] As used herein, "Group IV" may refer to Group IVA and Group IVB, and examples of Group IV metals may be Si, Ge, and Sn, without being limited thereto. As used herein, the term "metal" may include semi-metals such as Si.

[0041] As used herein, “Group I” may refer to Group IA and Group IB, and examples may include Li, Na, K, Rb, and Cs, without being limited thereto.

[0042] As used herein, “Group V” may refer to Group VA, and examples may include nitrogen, phosphorus, arsenic, antimony, and bismuth, without being limited thereto.

[0043] As used herein, "Group VI" may refer to Group VIA, and examples may include sulfur, selenium, and tellurium, without being limited thereto.

[0044] Figure 1 is a cross-sectional view showing a display device according to an embodiment.

[0045] Reference Figure 1According to one embodiment, a display device 100 has a structure in which a first electrode 111, a pixel defining layer 112, an organic emission layer 113, a second electrode 114, a light recycling layer 115 and a color filter layer 116 including quantum dots 16 are sequentially disposed on a substrate 110.

[0046] The substrate 110 may be a transparent insulating substrate and may be made of a material having flexibility. The substrate 110 may include a glass or polymer material in a film form having a glass transition temperature (Tg) greater than about 150° C. For example, it includes a material based on COC (cyclic olefin copolymer) or COP (cyclic olefin polymer).

[0047] On the other hand, although there is no Figure 1 10 is a schematic diagram showing a driving circuit, but the driving circuit may also be directly disposed on the substrate 110. The driving circuit may be connected to the organic emission layer 113 to be described later. The driving circuit may include: at least one line including a scan line, a data line, a driving power line, a common power line, etc.; at least two thin film transistors (TFTs) connected to the line and corresponding to one organic light emitting diode; and at least one capacitor, etc. The driving circuit may have various known structures.

[0048] The first electrode 111 may be disposed on the substrate 110 , specifically, directly on the driving circuit. In one embodiment, the first electrode 111 may be directly connected to the driving circuit and may allow current to flow to the organic emission layer 113 .

[0049] In one embodiment, the first electrode 111 may include silver, aluminum, chromium, molybdenum, tungsten, titanium, gold, palladium or an alloy thereof, and a metal oxide such as molybdenum oxide, tungsten oxide, vanadium oxide, rhenium oxide, niobium oxide, tantalum oxide, titanium oxide, zinc oxide, nickel oxide, copper oxide, cobalt oxide, manganese oxide, chromium oxide, indium oxide, etc., or a combination thereof. The first electrode 111 may have a single-layer structure or may have a multi-layer structure of two or more layers.

[0050] However, the first electrode 111 according to an embodiment is not necessarily limited thereto. It may include a material having light transmittance to light in the infrared or ultraviolet (UV) wavelength region, or a material having semi-transmittance to selectively transmit only light in a specific wavelength region. It may also be used as a reflective electrode to reflect light in the visible light wavelength region.

[0051] The pixel defining layer 112 is disposed on the first electrode 111. The pixel defining layer 112 may be formed of an organic material, an inorganic material, or the like. For example, the pixel defining layer 112 may include a photoresist, an organic material (such as a polypropylene-based resin, a polyimide-based resin, an acrylic-based resin, or the like), or an inorganic material (such as a silicon compound). For non-limiting examples, the pixel defining layer 112 may be formed using a photoresist including a black pigment. In this case, the pixel defining layer 112 may have a light blocking function.

[0052] The pixel defining layer 112 may include nanostructured scattering particles dispersed therein. The scattering particles may include inorganic particles or polymer particles. For example, inorganic particles (such as silica, TiO 2 、ZrO 2 etc.) or polymer particles (such as polystyrene, polymethyl methacrylate (PMMA), etc.) may be included.

[0053] In one embodiment, the pixel defining layer 112 includes an opening 1112 exposing a portion of the first electrode 111. The side portion of the pixel defining layer 112 formed by the opening 1112 may have an inclined structure. That is, the side surface of the pixel defining layer 112 may be inclined rather than vertical relative to the upper surface of the substrate 110.

[0054] In one embodiment, the pixel defining layer 112 may define a pixel region of the display device 100 through the opening 1112. The region in which the opening 1112 of the pixel defining layer 112 is provided may be a pixel region that emits light, and the region in which the opening 1112 is not provided may be a non-light emitting region in which light is blocked by a light blocking member to be described later.

[0055] In one embodiment, the pixel area of ​​the display device 100 may include a first pixel area PX1, a second pixel area PX2, and a third pixel area PX3. Each of the first pixel area PX1, the second pixel area PX2, and the third pixel area PX3 may emit light having a different wavelength region. That is, the first pixel area PX1 may emit a first light, the second pixel area PX2 may emit a second light, and the third pixel area PX3 may emit a third light, wherein the first light to the third light may be lights of different wavelength regions.

[0056] Each of the first light, the second light, and the third light may vary according to the type of light emitted from the organic emission layer 113, the type of quantum dots 16 included in the color filter layer 116. However, the first light may be red light, the second light may be green light, and the third light may be blue light. In this case, the first light may belong to a wavelength region of about 620 nm to about 680 nm, the second light may belong to a wavelength region of about 510 nm to about 580 nm, and the third light may belong to a wavelength region of about 380 nm to about 488 nm.

[0057] However, the embodiment is not necessarily limited thereto, and the first to third lights may be different combinations of red light, green light, and blue light (which may be white light), and may be, for example, magenta, yellow, and cyan lights, respectively.

[0058] In one embodiment, the organic emission layer 113 may induce electroluminescence of the organic light emitting material and thus emit light having a predetermined wavelength. The organic emission layer 113 may be disposed on the pixel defining layer 112 but electrically contact the first electrode 111 through the aforementioned opening 1112 .

[0059] The organic emission layer 113 includes a first organic emission layer 113a disposed in a region corresponding to the first pixel region PX1, a second organic emission layer 113b disposed in a region corresponding to the second pixel region PX2, and a third organic emission layer 113c disposed in a region corresponding to the third pixel region PX3. The first to third organic emission layers 113a, 113b, and 113c emit light having the same wavelength region or different wavelength regions, respectively.

[0060] In one embodiment, each of the first to third organic emission layers 113a, 113b, and 113c can emit a third light. When the first to third organic emission layers 113a, 113b, and 113c emit the same light, respectively, the same organic light-emitting material is used, which is convenient in terms of process. On the other hand, when the third light having higher energy than the first light or the second light is emitted, a well-known quantum dot that converts the third light into the first light and / or the second light can be used as the quantum dot 16 to be described later, and the third pixel region PX3 does not need to be provided with a color filter layer, so it can contribute to cost and process.

[0061] In one embodiment, the organic emission layer 113 may extend to a portion of the upper surface of the pixel defining layer 112 along the inclined structure at the side of the pixel defining layer 112. Since the organic emission layer 113 extends to the portion of the upper surface of the pixel defining layer 112, the color filter layer 116 to be described later may completely overlap with the region in which the organic emission layer 113 is formed, and in addition, when viewed from the top of the display device 100, the area of ​​the organic emission layer 113 may be larger than the area of ​​the color filter layer 116.

[0062] On the other hand, although there is no Figure 1 , but the organic emission layer 113 may include: a light-emitting portion including the aforementioned organic light-emitting material; and various auxiliary layers for supplying, transporting, and blocking electrons / holes to the light-emitting portion, respectively. The auxiliary layers may include an electron transport layer (ETL), a hole transport layer (HTL), an electron injection layer (EIL), a hole injection layer (HIL), an electron blocking layer, a hole blocking layer, or a combination thereof. Each of the auxiliary layers may be formed by a known formation method using a known material.

[0063] The second electrode 114 is disposed on the organic emission layer 113. In one embodiment, the second electrode 114 is formed to cover the organic emission layer 113 and even to cover an upper surface of the pixel defining layer 112 that is not covered by the organic emission layer 113 but is exposed, and thus may be a common electrode.

[0064] In one embodiment, the second electrode 114 may be used as a light-transmitting electrode through which light emitted from the organic emission layer 113 is transmitted. In one embodiment, the second electrode 114 may include at least one of silver (Ag), aluminum (Al), copper (Cu), gold (Au) and alloys thereof, or metal oxides such as molybdenum oxide, tungsten oxide, vanadium oxide, rhenium oxide, niobium oxide, tantalum oxide, titanium oxide, zinc oxide, nickel oxide, copper oxide, cobalt oxide, manganese oxide, chromium oxide, indium oxide, etc., or a combination thereof.

[0065] However, the second electrode 114 according to an embodiment is not necessarily limited thereto, but may include a semi-transmissive material that selectively transmits light of a predetermined wavelength region, for example, the third light, and specifically, light of a wavelength region of about 380 nm to about 488 nm.

[0066] The light recycling layer 115 may be disposed on the second electrode 114. The light recycling layer 115 may perform a function of transmitting at least the third light but reflecting the first light and the second light different from the third light. In other words, the light recycling layer 115 may be used as a band pass filter (BPF) that selectively transmits light of a wavelength region corresponding to the third light. Specifically, the light recycling layer 115 may be a so-called short wave pass filter (SWPF) that selectively transmits blue light having a relatively short wavelength region but blocks light having a wavelength region other than blue light (e.g., green light, yellow light, red light, etc.).

[0067] The light recycling layer 115 is disposed right on the second electrode 114 and directly contacts the second electrode 114 , and thus may be formed to cover all upper surfaces of the organic emission layer 113 and the second electrode 114 .

[0068] In one embodiment, the light recycling layer 115 may be formed as an integral layer that completely covers the first to third pixel regions PX1, PX2, and PX3 and each non-luminescent region between the pixel regions, but is not necessarily limited thereto. For example, the light recycling layer 115 may overlap at least the first pixel region PX1 and the second pixel region PX2, but is not formed on the remaining non-luminescent regions and / or the third pixel region PX3.

[0069] Therefore, when the third light emitted from the organic emission layer 113 passes through the light recovery layer 115 and is supplied to the color filter layer 116, the color filter layer 116 can emit at least the first light (first pixel area PX1) and / or the second light (second pixel area PX2), and thus emit them outside the display device 100.

[0070] In other words, the display device 100 according to an embodiment recycles a portion of light radiated from the quantum dots 16 in all directions by using the light recycling layer 115 , and thus may exhibit improved light efficiency particularly with respect to the first light and / or the second light.

[0071] On the other hand, despite Figure 1 Although not shown in the figure, the light recycling layer 115 may include a plurality of layers having different refractive indices. The light recycling layer 115 may be formed, for example, by alternately stacking two layers having different refractive indices, for example, by alternately stacking a layer having a high refractive index and a layer having a low refractive index.

[0072] The layer having a high refractive index may include, for example, at least one of hafnium oxide, tantalum oxide, titanium oxide, zirconium oxide, magnesium oxide, cesium oxide, lanthanum oxide, indium oxide, niobium oxide, aluminum oxide, and silicon nitride, but may include various materials having a higher refractive index than the layer having a low refractive index.

[0073] The layer having a low refractive index may include, for example, silicon oxide, but may include various materials having a lower refractive index than the layer having a high refractive index.

[0074] As the refractive index difference between the layer having a high refractive index and the layer having a low refractive index becomes larger, the light recycling layer 115 having excellent light transmittance with respect to the third light and excellent light reflectance with respect to the first light or the second light may be formed.

[0075] In the light recycling layer 115, each thickness and number of the layer with a high refractive index and the layer with a low refractive index may be determined according to the refractive index and the reflection wavelength of each layer. For example, in the light recycling layer 115, each layer with a high refractive index may have a thickness of about 3 nm to about 300 nm, and in the light recycling layer 115, each layer with a low refractive index may have a thickness of about 3 nm to about 300 nm. The total thickness of the light recycling layer 115 may be, for example, in the range of about 0.5 μm to about 5 μm. In the light recycling layer 115, the thickness and material of each layer with a high refractive index may be the same or different, and the thickness and material of each layer with a low refractive index may be the same or different.

[0076] In one embodiment, the light recycling layer 115 may have a light transmittance of at least greater than or equal to about 90% for the third light, for example, greater than or equal to about 91%, greater than or equal to about 92%, greater than or equal to about 93%, greater than or equal to about 94%, greater than or equal to about 95%, greater than or equal to about 96%, greater than or equal to about 97%, greater than or equal to about 98%, greater than or equal to about 99%, or even about 100%.

[0077] In addition, the light recycling layer 115 can have a low light transmittance for light in the remaining visible light wavelength region except the third light, and in particular, can have a light transmittance of less than or equal to about 20% for the first light and the second light, for example, less than or equal to about 15%, less than or equal to about 10%, less than or equal to about 9%, less than or equal to about 8%, less than or equal to about 7%, less than or equal to about 6%, less than or equal to about 5%, less than or equal to about 4%, less than or equal to about 3%, less than or equal to about 2%, less than or equal to about 1%, or even about 0%.

[0078] The color filter layer 116 is disposed on the light recycling layer 115 and includes the quantum dots 16, thus performing a function of converting light supplied from the organic emission layer 113. In one embodiment, the color filter layer 116 may be formed by using a mixture including a binder, a photopolymerizable monomer, a photoinitiator and a solvent, and the quantum dots 16.

[0079] In one embodiment, the color filter layer 116 may be disposed to correspond to the pixel region. Specifically, in one embodiment, the color filter layer 116 may exist only on the first pixel region PX1 and the second pixel region PX2.

[0080] In one embodiment, at least a portion of the color filter layer 116 may be received in the opening 1112. In other words, Figure 1 As shown, a lower portion of the color filter layer 116 may be received in the opening 1112 .

[0081] In one embodiment, the color filter layer 116 includes: a first color filter layer 116r, which includes a first quantum dot 16r that converts the third light into the first light and is disposed on the first pixel area PX1; and a second color filter layer 116g, which includes a second quantum dot 16g that converts the third light into the second light and is disposed on the second pixel area PX2.

[0082] In one embodiment, the color filter layer 116 is formed to completely overlap with the organic emission layer 113, but the width direction length of the organic emission layer 113 may be longer than the width direction length of the color filter layer 116. Figure 1 , the width direction length W of the first organic emission layer 113a and the second organic emission layer 113b L1 and W L2 The width direction length W of the first color filter layer 116r and the second color filter layer 116g may be greater than the width direction length W of the first color filter layer 116r and the second color filter layer 116g. C1 and W C2 long.

[0083] When the organic emission layer 113 and the color filter layer 116 have this structural relationship, referring to a top view of the display device 100 , the area of ​​the organic emission layer 113 may be greater than the area of ​​the color filter layer 116 .

[0084] Therefore, the third light emitted from the organic emission layer 113 may enter substantially at a perpendicular angle to the light recycling layer 115 and / or the color filter layer 116 (i.e., the incident angle of the third light to the light recycling layer 115 and / or the color filter layer 116 is substantially 0°). Therefore, the display device 100 may particularly exhibit improved light efficiency relative to the first light and / or the second light.

[0085] In one embodiment, the width of organic emission layer 113 may be greater than about 1.00 times the width of color filter layer 116 or greater than or equal to about 1.01 times the width of color filter layer 116. Within this range, the width of organic emission layer 113 may be less than or equal to about 1.20 times the width of color filter layer 116, less than or equal to about 1.15 times the width of color filter layer 116, less than or equal to about 1.10 times the width of color filter layer 116, less than or equal to about 1.08 times the width of color filter layer 116, less than or equal to about 1.05 times the width of color filter layer 116, and less than or equal to about 1.03 times the width of color filter layer 116.

[0086] For example, refer to Figure 1 , the width W of the first and second organic emission layers 113a and 113b L1 and W L2 The width W of the first and second color filter layers 116a and 116b may be greater than C1 and W C2 The width W of the first and second color filter layers 116a and 116b is about 1.00 times or greater than or equal to C1 and W C2 Within this range, the width W of the first and second organic emission layers 113a and 113b is about 1.01 times of that of the first and second organic emission layers 113a and 113b. L1 and W L2 The width W of the first and second color filter layers 116a and 116b may be less than or equal to C1 and W C2 1.20 times of the width W of the first and second color filter layers 116a and 116b, which is less than or equal to C1 and W C2 1.15 times of the width W of the first and second color filter layers 116a and 116b, which is less than or equal to C1 and W C2 1.10 times of the width W of the first and second color filter layers 116a and 116b, which is less than or equal to C1 and W C2 , which is less than or equal to the width W of the first and second color filter layers 116a and 116b. C1 and W C2 1.05 times of the width W of the first and second color filter layers 116a and 116b, which is less than or equal to C1 and W C2 About 1.03 times of .

[0087] For example, the width W of the first and second organic emission layers 113a and 113b is L1 and W L2 The width W of the first and second color filter layers 116a and 116b may be greater than C1 and WC2 about 1.00 times and less than or equal to about 1.20 times thereof, greater than about 1.00 times and less than or equal to about 1.15 times thereof, greater than about 1.00 times and less than or equal to about 1.10 times thereof, greater than about 1.00 times and less than or equal to about 1.08 times thereof, greater than about 1.00 times and less than or equal to about 1.05 times thereof, greater than about 1.00 times and less than or equal to about 1.03 times thereof.

[0088] For example, the width W of the first and second organic emission layers 113a and 113b is L1 and W L2 The width W of the first and second color filter layers 116a and 116b may be greater than or equal to C1 and W C2 The width W of the first and second organic light emitting layers 113a and 113b is about 1.01 times and less than or equal to about 1.20 times, about 1.01 times or more and less than or equal to about 1.15 times, about 1.01 times or more and less than or equal to about 1.10 times, about 1.01 times or more and less than or equal to about 1.08 times, about 1.01 times or more and less than or equal to about 1.05 times, about 1.01 times or more and less than or equal to about 1.03 times. By making the width W of the first and second organic light emitting layers 113a and 113b L1 and W L2 Within this range, an effect of improvement in light efficiency can be obtained without sacrificing a light emitting area.

[0089] In one embodiment, the width of the organic emission layer 113 may be about 80% or more of the total thickness of the organic emission layer 113, the second electrode 114, and the light recycling layer 115. Figure 1 , the width W of the first and second organic emission layers 113a and 113b L1 and W L2 The width W of the first and second organic emission layers 113a and 113b may be about 80% or more of the total thickness of the first organic emission layer 113a or the second organic emission layer 113b, the second electrode 114, and the light recycling layer 115. Within this range, the width W of the first and second organic emission layers 113a and 113b may be about 80% or more of the total thickness of the first organic emission layer 113a or the second organic emission layer 113b. L1 and W L2 The thickness of the first and second organic emission layers 113a and 113b may be about 80% to 200%, about 80% to 150%, about 80% to 120%, about 86% to 200%, about 86% to 150%, or about 86% to 120% of the total thickness of the first organic emission layer 113a or the second organic emission layer 113b, the second electrode 114, and the light recycling layer 115. By making the width W of the first and second organic emission layers 113a and 113b L1 and W L2Within this range, the third light emitted from the first and second organic light emitting layers 113a and 113b may enter the light recycling layer 115 and / or the color filter layer 116 at an angle substantially perpendicular to the light recycling layer 115 and / or the color filter layer 116 without losing the light emitting area.

[0090] Then refer to Figures 2 to 4 The structural relationship between the organic emission layer 113 and the color filter layer 116 and the effect of improving light efficiency caused thereby are described.

[0091] On the other hand, the quantum dots 16 included in the color filter layer 116 have a discontinuous energy band gap due to the quantum confinement effect, so the incident light passing through the quantum dots 16 can be converted into light having a specific wavelength and radiated. Therefore, the light converted by using the quantum dots 16 has excellent color reproducibility and color purity.

[0092] In one embodiment, the material of the quantum dot 16 is not particularly limited, and known or commercially available quantum dots can be used. For example, each quantum dot 16 according to one embodiment can be, for example, a II-VI compound (which does not include Cd), a III-V compound, an IV-VI compound, a IV element or compound, an I-III-VI compound, an I-II-IV-VI compound (which does not include Cd), or a combination thereof.

[0093] The quantum dots 16 according to an embodiment may include cadmium or not. When the quantum dots 16 are non-cadmium-based quantum dots, they are non-toxic compared to conventional cadmium-based quantum dots, and thus non-hazardous and environmentally friendly.

[0094] The II-VI compounds can be selected from the following: binary compounds selected from ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS and mixtures thereof; ternary compounds selected from ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS and mixtures thereof; and quaternary compounds selected from HgZnTeS, HgZnSeS, HgZnSeTe, HgZnSTe and mixtures thereof. The II-VI compounds can also include Group III metals.

[0095] The III-V compounds may be selected from the following: binary compounds selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb and mixtures thereof; ternary compounds selected from GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, InZnP and mixtures thereof; and quaternary compounds selected from GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb and mixtures thereof. The III-V compounds may also include Group II metals (InZnP).

[0096] The IV-VI compounds may be selected from the following: binary compounds selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe and mixtures thereof; ternary compounds selected from SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe and mixtures thereof; and quaternary compounds selected from SnPbSSe, SnPbSeTe, SnPbSTe and mixtures thereof. Examples of I-III-VI compounds may be CuInSe 2 、CuInS 2 , CuInGaSe and CuInGaS, but not limited thereto. Examples of I-II-IV-VI group compounds may be CuZnSnSe and CuZnSnS, but not limited thereto. Examples of IV group compounds may be: a single substance selected from Si, Ge and a mixture thereof; and a binary compound selected from SiC, SiGe and a mixture thereof.

[0097] The binary compound, ternary compound or quaternary compound is present in the particle at a uniform concentration or in partially different concentrations in the same particle, respectively.

[0098] According to one embodiment, quantum dot 16 may have a core-shell structure including a core of a semiconductor nanocrystal and a shell of another semiconductor nanocrystal surrounding the core. The core and the shell may have a concentration gradient, wherein the concentration of the element (s) of the shell decreases toward the core. In addition, quantum dot 16 may have a structure including a core of a semiconductor nanocrystal and multiple shells surrounding the core. Here, the multilayer shell structure has a structure of two or more shells, and each layer may have a single component or alloy, or may have a concentration gradient.

[0099] When the quantum dot 16 has a core-shell structure, the material component of the shell has a band gap energy greater than the band gap energy of the core, which can exhibit an effective quantum confinement effect. However, the embodiment is not limited thereto. In addition, in a multi-layer shell, the shell away from the core can have a higher band gap energy than the shell near the core, and the quantum dot can have a wavelength range from ultraviolet (UV) to infrared.

[0100] The quantum dots 16 can have a quantum efficiency greater than or equal to about 10%, for example, greater than or equal to about 20%, greater than or equal to about 30%, greater than or equal to about 40%, greater than or equal to about 50%, greater than or equal to about 60%, greater than or equal to about 70%, greater than or equal to about 80%, greater than or equal to about 90%, or even a quantum efficiency of 100%.

[0101] In addition, in the display device 100, the quantum dots 16 may have a relatively narrow spectrum to improve color purity or color reproducibility. The quantum dots 16 may have, for example, a full width at half maximum (FWHM) of a photoluminescence wavelength spectrum of less than or equal to about 45 nm, less than or equal to about 40 nm, or less than or equal to about 30 nm and greater than or equal to about 1 nm, greater than or equal to about 2 nm, or greater than or equal to about 3 nm. Within the range, the color purity or color reproducibility of the display device 100 may be improved.

[0102] The quantum dots 16 may have a particle diameter of about 1 nm to about 100 nm (for non-spherical particles, the longest diameter). For example, the quantum dots 16 may have a particle diameter of about 1 nm to about 20 nm, such as about 2 nm (or about 3 nm) to about 15 nm.

[0103] In addition, the shape of the quantum dot 16 can be a general shape in the art, and therefore may not be particularly limited. For example, the quantum dot 16 may have a spherical, elliptical, tetrahedral, pyramidal, cuboctahedral, cylindrical, polyhedral, multi-armed, or cubic nanoparticle, nanotube, nanowire, nanofiber, nanosheet, or a combination thereof. The quantum dot 16 may have any cross-sectional shape.

[0104] The quantum dots 16 may be commercially available or may be synthesized in any manner. For example, several nanometer-sized quantum dots 16 may be synthesized according to a wet chemical process. In a wet chemical process, a precursor material is reacted in an organic solvent to grow crystalline particles. Here, the organic solvent or the material forming the ligand naturally coordinates with the surface of the quantum dots 16 to control crystal growth.

[0105] The amount of organic material coordinated on the surface of the quantum dot 16 can be less than or equal to about 50 wt% of the weight of the quantum dot, such as less than or equal to about 30 wt%, less than or equal to about 20 wt%, or less than or equal to about 10 wt%, and greater than or equal to about 0.001 wt% based on the total weight of the quantum dot, such as greater than or equal to about 0.01 wt% or greater than or equal to about 0.1 wt%. Such organic material can include ligands bound to the surface of the quantum dot 16, residual organic solvents, or combinations thereof.

[0106] In an implementation, the color filter layer 116 may include a predetermined amount of quantum dots 16 to exhibit excellent light emitting efficiency.

[0107] For example, the quantum dots 16 may be included, for example, in an amount greater than or equal to about 5 wt %, greater than or equal to about 10 wt %, greater than or equal to about 15 wt %, or greater than or equal to about 20 wt %, for example, less than or equal to about 98 wt %, less than or equal to about 95 wt %, less than or equal to about 90 wt %, less than or equal to about 85 wt %, less than or equal to about 80 wt %, less than or equal to about 75 wt %, less than or equal to about 70 wt %, less than or equal to about 65 wt %, less than or equal to about 60 wt %, less than or equal to about 55 wt %, or less than or equal to about 50 wt %, or for example, in a range of about 5 wt % to about 98 wt %, about 20 wt % to about 98 wt %, about 20 wt % to about 90 wt %, about 20 wt % to about 85 wt %, or about 50 wt % to about 85 wt %.

[0108] However, the embodiment is not necessarily limited thereto, but the specific amount of the quantum dots 16 may vary according to the material of the quantum dots 16 used, the type of emitted light, the material and thickness of the light recycling layer 115 , and the like.

[0109] On the other hand, although there is no Figure 1 , but the first color filter layer 116r and the second color filter layer 116g according to one embodiment may further include a light scatterer, respectively, so as to improve the emission efficiency of the first light or the second light and the front / side brightness uniformity. The light scatterer may include any material that scatters light uniformly without particular limitation, such as silica (SiO 2 ), hollow silica (SiO2 ), TiO 2 、ZrO 2 、Al 2 O 3 、In 2 O 3 、ZnO、SnO 2 , Sb 2 O 3 , ITO or a combination thereof.

[0110] In one embodiment, the display device 100 may further include a transmission layer 117 adjacent to at least one of the first color filter layer 116r and the second color filter layer 116g in a direction parallel to the upper surface of the substrate 110. The transmission layer 117 may be formed on the third pixel region PX3. The transmission layer 117 may be formed of a transparent polymer and transmit the third light emitted from the third organic emission layer 113c, so that the third pixel region PX3 may emit the third light. In other words, the display device 100 may further include a substrate 110, the first electrode may be disposed on the upper surface of the substrate 110, and the display device 100 may further include a transmission layer 117 adjacent to the first color filter layer 116r, the second color filter layer 116g, or a combination thereof in a direction parallel to the upper surface of the substrate.

[0111] The transmission layer 117 includes a material capable of transmitting the incident third light without a specific phosphor and / or quantum dot. For example, the transmission layer 117 may include a polymer including a photosensitive resin or the like.

[0112] On the other hand, despite Figure 1 Although not shown in the figure, the transmission layer 117 according to an embodiment may further include a light scatterer to improve the emission efficiency of the third light and the front / side brightness uniformity. Examples of the light scatterer may be the same as the light scatterers included in the first color filter layer 116r and the second color filter layer 116g described above, and therefore will not be described in detail.

[0113] The display device 100 according to an embodiment may further include a light blocking member 118 disposed in a gap between each adjacent two of the first color filter layer 116r, the second color filter layer 116g, and the transmission layer 117. The light blocking member 118 may be formed of a light-impermeable material, such as metal particles (such as chromium (Cr), silver (Ag), molybdenum (Mo), nickel (Ni), titanium (Ti), tantalum (Ta), etc.), oxides of the metal particles, or a combination thereof. The light blocking member 118 may prevent color mixing and light leakage of the display device 100, thereby improving contrast.

[0114] In the following, refer to Figures 2 to 4, describing the structural relationship between the organic emission layer 113 and the color filter layer 116 according to an embodiment and the light efficiency improvement effect caused thereby.

[0115] Figure 2 is a schematic diagram schematically illustrating a light conversion process of a color filter layer in one pixel of a display device according to an embodiment, Figure 3 is a schematic diagram schematically illustrating a light conversion process of a color filter layer when the requirements of a display device according to an embodiment are not met, Figure 4 is a graph showing wavelength-dependent light transmittance variation of a light recycling layer according to viewing angle variation.

[0116] Figure 2 and Figure 3 The first pixel region PX1 is shown as an example, which is adopted for convenience of explanation, but the structural relationship and the effects produced thereby, which will be described later, may be equally applied to the second pixel region PX2.

[0117] on the other hand, Figure 4 Shown is a wavelength-dependent light transmittance of the light recycling layer at each viewing angle of 0°, 15°, 30°, 45°, and 60° with respect to the viewing angle of light incident into the light recycling layer.

[0118] First, refer to Figure 2 In the display device 100 according to an embodiment, the blue light ( Figure 2 B) may pass through the second electrode 114 and sequentially enter the light recycling layer 115 and the first color filter layer 116r.

[0119] The incident light enters the first quantum dot 16r, and the first quantum dot 16r converts the blue light (B) into red light and thus radiates it in all directions. Here, the red light radiated to all light emission directions of the display device 100 is emitted from the display device 100 ( Figure 2 Here, the red light radiated to the direction of the light recycling layer 115 is reflected (recycled) on the interface of the light recycling layer 115 and then emitted from the display device 100 ( Figure 2 of R').

[0120] In addition, refer to Figure 2 , the blue light (B) respectively entering the light recycling layer 115 and the first color filter layer 116r may enter at a substantially vertical angle (substantially at an incident angle of 0°).

[0121] In other words, in the display device according to an embodiment, blue light (B) may enter at an angle substantially perpendicular to all interfaces of the light recycling layer 115 and the first color filter layer 116 r in the first pixel region PX1 .

[0122] on the other hand, Figure 3 It is shown that, unlike the display device 100 according to an embodiment, the first color filter layer 6 does not completely overlap with the first organic emission layer 3 , but extends longer than the first organic emission layer 3 .

[0123] Here, the blue light ( Figure 3 B) enters the second electrode 4, the light recycling layer 5 and the first color filter layer 6 at an angle of α° (0<α<90°). The incident angle may vary according to the width of the region where the end of the first organic emission layer 3 does not overlap with the light recycling layer 5.

[0124] However, referring to Figure 4 , the light transmittance of the light recycling layer may vary according to the incident angle, and in particular, the light transmittance with respect to short wavelength light (such as blue light, etc.) may vary greatly.

[0125] Specifically, when the incident angle is substantially 0° (eg Figure 2 As shown), the light recycling layer 115 can exhibit a light transmittance greater than or equal to about 90% over the entire blue light wavelength region, such as greater than or equal to about 90%, greater than or equal to about 91%, greater than or equal to about 92%, greater than or equal to about 93%, greater than or equal to about 94%, greater than or equal to about 95%, greater than or equal to about 96%, greater than or equal to about 97%, greater than or equal to about 98%, greater than or equal to about 99%, or even about 100%. Figure 4 Therefore, the display device according to one embodiment has Figure 2 The structure shown can be used as an excellent blue light transmission filter.

[0126] On the other hand, Figure 3 As shown, in a display device with an incident angle of α°, as α° gradually increases to 15°, 30°, 45° and 60°, the light transmittance curve of the light recovery layer 5 gradually shifts to the left, and the display device will exhibit uneven light transmittance in the blue light wavelength region, and the light transmittance will be greatly deteriorated in certain wavelength regions.

[0127] In addition, as the incident angle gradually increases, the light transmittance of the light recycling layer with respect to the long wavelength region (such as the green and red wavelength regions) increases unintentionally. The reason for this is believed to be that the light transmittance curve shifts to the left according to the increase in the incident angle.

[0128] Therefore, as the incident angle of the third light entering the light recycling layer 5 gradually increases, not only the blue light transmittance gradually deteriorates, but also the light transmittance with respect to light having a long wavelength longer than that of the blue light increases unintentionally. Therefore, when the incident angle entering the light recycling layer is not adjusted to an appropriate level, the light recycling layer not only fails to perform the desired function, but also greatly deteriorates the light efficiency of the display device.

[0129] Therefore, when the area of ​​the organic emission layer 113 of each pixel is formed to be larger than the area of ​​the color filter layer 116, as shown in the display device 100 according to an embodiment, blue light can enter substantially vertically at all interfaces of the light recycling layer 115 and the color filter layer 116 in each pixel region. Therefore, light efficiency, especially in the first pixel region PX1 and the second pixel region PX2 where the color filter layer 116 is provided, can be improved.

[0130] On the other hand, in the following, reference is made to Figures 5 to 9 , showing various exemplary variations of a display device according to an embodiment.

[0131] Figures 5 to 8 are cross-sectional views showing various exemplary variations of applying a concavo-convex structure to a second electrode and / or a light recycling layer of a display device according to an embodiment.

[0132] Reference Figures 5 to 8 , the second electrode and / or the light recycling layer according to an exemplary variation may have a concavo-convex structure.

[0133] For example, Figure 5 As shown, the entire upper surface of the second electrode 114' may have a concave-convex structure, and as shown in FIG. Figure 6 As shown, the entire upper surface of the light recycling layer 115" may have a concave-convex structure, and as shown in FIG. Figure 7 As shown, the entire upper surface of the second electrode 114''' and the entire upper / lower surfaces of the light recycling layer 115''' may have a concavo-convex structure.

[0134] The concavo-convex structure does not need to be formed on the entire second electrode and / or light recycling layer. Figure 8 As shown, an upper surface of the second electrode 114"" overlapping with an upper surface of the pixel defining layer and a portion of a lower surface of the light recycling layer 115"" may have a concavo-convex structure.

[0135] In this way, when the concavo-convex structure is applied to the surface of the second electrode and / or the light recycling layer, the vertical incidence ratio of the third light to the light recycling layer and the color filter layer can be further improved, and the light efficiency of the display device can be further improved.

[0136] Fig. 9is a cross-sectional view illustrating a display device further including a third light blocking layer according to an exemplary variation.

[0137] Reference Fig. 9 The display device 100' according to an exemplary variation may further include a third light blocking layer 119 disposed on the color filter layer 116 and overlapping at least one of the first color filter layer 116r and the second color filter layer 116g.

[0138] The third light blocking layer 119 may be formed of a material that transmits the first light and the second light having relatively long wavelengths but reflects or absorbs the third light having a short wavelength. In other words, the third light blocking layer 119 may be a long wavelength pass filter (LWPF), thus performing the opposite function of the above-mentioned light recycling layer 115.

[0139] On the other hand, similar to the above-mentioned light recycling layer 115, the third light blocking layer 119 may also include a plurality of layers having different refractive indices. The third light blocking layer 119 may be formed, for example, by alternately stacking two layers having different refractive indices, for example, by alternately stacking a material having a high refractive index and another material having a low refractive index.

[0140] The material having a high refractive index, the material having a low refractive index, and the thickness of each of them are the same as those of the above-mentioned light recycling layer 115 , but the third light blocking layer 119 may be formed to function as the above-mentioned long wavelength pass filter.

[0141] In one embodiment, the third light blocking layer 119 may extend from the first pixel region PX1 to the second pixel region PX2 as an integral layer. However, the third light blocking layer 119 is not limited thereto but may be variously modified under the condition of covering at least the first color filter layer 116r and the second color filter layer 116g.

[0142] In this manner, when two optical filters of the light recycling layer 115 and the third light blocking layer 119 are used to control light emitted from the first and second pixel regions PX1 and PX2 , the display device 100 ′ may have excellent light efficiency and emit light with high color purity.

[0143] While the present disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0144] <Description of Symbols>

[0145] 16 (16r and 16g): Quantum Dot 100: Display Device

[0146] 110: substrate 111: first electrode

[0147] 112: Pixel limiting layer

[0148] 113 (113a, 113b and 113c): organic emission layer

[0149] 114: second electrode 115: light recovery layer

[0150] 116 (116r and 116g): Color filter layer 117: Transmission layer

[0151] 118: light blocking member 119: third light blocking layer

[0152] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0009438 filed in the Korean Intellectual Property Office on January 24, 2019, the entire contents of which are incorporated herein by reference.

Claims

1. A display device, comprising: The first electrode, a pixel defining layer, disposed on the first electrode and having an opening, an organic emission layer, disposed on the pixel defining layer, the organic emission layer being electrically connected to the first electrode through the opening and emitting a third light, A second electrode is disposed on the organic emission layer. a light recycling layer disposed on the second electrode, and a color filter layer disposed on the light recycling layer and comprising quantum dots, wherein the color filter layer completely overlaps the organic emission layer, and The width direction length of the organic emission layer is longer than the width direction length of the color filter layer, and The light recycling layer is configured to transmit the third light and reflect the first light, the first light having a different wavelength from the third light.

2. The display device according to claim 1, wherein a side portion of the pixel defining layer formed by the opening has an inclined structure, and The organic emission layer extends to a portion of an upper surface of the pixel defining layer along the inclined structure at the side of the pixel defining layer. 3 . The display device according to claim 1 , wherein a width of the opening is longer than or equal to a width of the color filter layer. The display device according to claim 3 , wherein at least a portion of the color filter layer is received in the opening.

5. The display device according to claim 1, wherein The light recycling layer reflects the second light, and the second light has a wavelength different from a wavelength of the third light, The quantum dots are configured to convert the third light provided from the organic emission layer into light of a different wavelength region. The display device according to claim 5 , wherein the first light is red light, the second light is green light, and the third light is blue light. 7 . The display device according to claim 5 , wherein the light recycling layer has a transmittance greater than or equal to 90% with respect to the third light. 8 . The display device according to claim 5 , wherein the light recycling layer has a transmittance of less than or equal to 20% with respect to the first light and the second light. 9 . The display device according to claim 5 , wherein the light recycling layer has a thickness in a range from 0.5 μm to 5 μm.

10. The display device according to claim 5, wherein The color filter layer comprises: a first color filter layer including first quantum dots that convert the third light into the first light, and The second color filter layer includes second quantum dots that convert the third light into the second light. 11 . The display device of claim 10 , wherein the first electrode is disposed on a substrate, the display device further comprising a transmission layer adjacent to at least one of the first color filter layer and the second color filter layer in a direction parallel to an upper surface of the substrate. 12 . The display device according to claim 11 , wherein the transmission layer and / or the color filter layer comprises a light scatterer. 13 . The display device according to claim 11 , further comprising a light blocking member between each adjacent two of the first color filter layer, the second color filter layer, and the transmission layer in the direction parallel to the upper surface of the substrate. 14 . The display device of claim 10 , wherein the light recycling layer overlaps at least one of the first color filter layer and the second color filter layer, respectively.

15. The display device according to claim 10, wherein The second electrode and the light recycling layer are in direct contact with each other, and At least a portion of the upper surface of the second electrode includes a concavo-convex structure.

16. The display device according to claim 10, wherein The second electrode and the light recycling layer are in direct contact with each other, and At least a portion of the upper surface and / or the lower surface of the light recycling layer includes a concavo-convex structure. 17 . The display device of claim 10 , further comprising a third light blocking layer disposed on the color filter layer and overlapping at least one of the first color filter layer and the second color filter layer.

18. The display device according to claim 1, wherein the quantum dots include II-VI compounds that do not contain Cd, III-V compounds, IV-VI compounds, IV elements or compounds, I-III-VI compounds, I-II-IV-VI compounds that do not contain Cd, or a combination thereof. The display device according to claim 1 , wherein the quantum dots have a core-shell structure.

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