Display device

Abstract

The present application relates to a display device. The display device can include: a substrate; a first electrode disposed on the substrate; a pixel definition film exposing an upper surface of the first electrode and covering a side portion of the first electrode; a second electrode disposed on the first electrode; a hole injection layer disposed between the first electrode and the second electrode and having an upper surface with a side portion protruding toward the second electrode; a light emitting layer disposed between the hole injection layer and the second electrode and having an upper surface with a side portion protruding toward the second electrode; and an electron injection layer disposed on the light emitting layer, wherein a shortest distance between a first fixed point defined at an intersection of a side portion of the upper surface of the hole injection layer and the pixel definition film and a second fixed point defined at an intersection of a side portion of the upper surface of the light emitting layer and the pixel definition film is greater than or equal to a dielectric breakdown limit distance of the light emitting layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a display device. More particularly, it relates to a display device that improves luminous efficiency by preventing current leakage. BACKGROUND

[0002] An organic light emitting display device is a self-emission type display device that displays an image using an organic light emitting diode (OLED) that emits light. Such an organic light emitting display device has high quality characteristics such as low power consumption, high brightness, fast response speed, wide viewing angle, and excellent contrast, and thus is spotlighted as a next generation display device.

[0003] An organic light emitting display device can be equipped with a light emitting layer using an organic light emitting substance between a first electrode and a second electrode. As an anode voltage and a cathode voltage are applied to the electrodes, respectively, holes injected from the first electrode move to the light emitting layer via a hole injection layer and a hole transport layer, and electrons move to the light emitting layer from the second electrode via an electron injection layer and an electron transport layer, so that the electrons and the holes can recombine in the light emitting layer. An exciton is generated by such recombination, and as the exciton changes from an excited state to a ground state, the light emitting layer emits light, so that an image can be displayed.

[0004] A substrate can be disposed in a lower portion of an organic light emitting diode (OLED), and a first electrode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, a second electrode, and an encapsulation layer can be disposed in order in an upper portion thereof.

[0005] A current leakage phenomenon can occur between the hole injection layer and the second electrode. In the case where the current leakage phenomenon occurs, there can be a problem in that the performance of an organic light emitting display device including the organic light emitting diode (OLED) is reduced. SUMMARY

[0006] An object of the present application is to provide a display device that prevents current leakage.

[0007] Another object of the present application is to provide a display device that improves luminous efficiency by adjusting the positions of fixing points of respective layers.

[0008] Another object of the present application is to provide a display device that improves luminous efficiency by forming a flat portion having a uniform thickness in a light emitting layer by adjusting side portions of respective layers.

[0009] However, the objects of the present application are not limited to the above-described objects, and the present application can achieve various extensions within the scope of the idea and field of the present application.

[0010] To achieve the above object of the present application, a display device according to an embodiment includes: a substrate; a first electrode disposed on the substrate; a pixel definition film exposing an upper surface of the first electrode and covering a side portion of the first electrode; a second electrode disposed on the first electrode; a hole injection layer disposed between the first electrode and the second electrode and having an upper surface with a side portion protruding toward the second electrode; a light emitting layer disposed between the hole injection layer and the second electrode and having an upper surface with a side portion protruding toward the second electrode; and an electron injection layer disposed on the light emitting layer, wherein a distance between a first fixed point defined at an intersection of the side portion of the upper surface of the hole injection layer and the pixel definition film and a second fixed point defined at an intersection of the side portion of the upper surface of the light emitting layer and the pixel definition film can be greater than or equal to a dielectric breakdown limit distance of the light emitting layer.

[0011] In an embodiment, the display device can further include a hole transport layer disposed between the hole injection layer and the light emitting layer.

[0012] In an embodiment, the hole injection layer can have a greater ink repellency to the pixel definition film than the hole transport layer.

[0013] In an embodiment, the display device can further include an electron transport layer disposed between the light emitting layer and the electron injection layer.

[0014] In an embodiment, a horizontal distance from the first fixed point to a point at which a flat portion of a center of the upper surface of the hole injection layer intersects with a curvature portion of the side portion can be 0.5 μm to 3 μm.

[0015] In an embodiment, a horizontal distance from the first fixed point to a point at which a flat portion of a center of the upper surface of the hole injection layer intersects with a curvature portion of the side portion can be 0.5 μm.

[0016] In an embodiment, a horizontal distance from the second fixed point to a point at which a flat portion of a center of the upper surface of the light emitting layer intersects with a curvature portion of the side portion can be 0.5 μm to 3 μm.

[0017] In an embodiment, a horizontal distance from the second fixed point to a point at which a flat portion of a center of the upper surface of the light emitting layer intersects with a curvature portion of the side portion can be 0.5 μm.

[0018] In an embodiment, the hole injection layer can have a greater ink repellency to the pixel definition film than the light emitting layer.

[0019] In one embodiment, the radius of curvature of the side portion of the upper surface of the hole injection layer may be greater than the radius of curvature of the side portion of the upper surface of the light-emitting layer.

[0020] In one embodiment, the upper surface of the hole injection layer may have a "U" shape.

[0021] In one embodiment, the upper surface of the hole injection layer has a central flat portion with a width greater than the width of the side portion of the upper surface of the hole injection layer.

[0022] In one embodiment, the upper surface of the hole injection layer may have a "W" shape.

[0023] In one embodiment, the upper surface of the hole injection layer may have a central flat portion, the height of which is lower than the height of the first fixed point and higher than the height of the lowest point of the curvature portion of the side portion of the upper surface of the hole injection layer, and has a width greater than the width of the side portion of the upper surface of the hole injection layer.

[0024] In one embodiment, the upper surface of the light-emitting layer may have a "U" shape.

[0025] In one embodiment, the upper surface of the light-emitting layer may have a central flat portion with a width greater than the width of the side portion of the upper surface of the light-emitting layer.

[0026] In a display device according to an embodiment of the present invention, since the shortest interval between a first fixed point at the junction of the side portion of the upper surface of the hole injection layer and the pixel definition film, and a second fixed point at the junction of the side portion of the upper surface of the light-emitting layer and the pixel definition film, is greater than or equal to the dielectric breakdown limit distance of the light-emitting layer, current leakage can be prevented. Accordingly, the luminous efficiency of the display device can be improved.

[0027] In a display device according to an embodiment of the present invention, current leakage is prevented by adjusting the length of the radius of curvature of the side portions of the light-emitting layer and the hole injection layer, thereby improving the luminous efficiency of the display device.

[0028] In a display device according to an embodiment of the present invention, the luminous efficiency of the display device can be improved by adjusting the morphology of the upper surfaces of the light-emitting layer and the hole injection layer.

[0029] However, the effects of the present invention are not limited to those described above, and various extensions can be achieved without departing from the spirit and scope of the present invention. Attached Figure Description

[0030] Figure 1 This is a cross-sectional view showing a display device according to an embodiment of the present invention.

[0031] Figure 2 It is shown in Figure 1 A cross-sectional view of a display device in which the shape of the upper surface of the hole injection layer is deformed.

[0032] Figure 3 It is shown in Figure 1 A cross-sectional view of a display device in which a hole transport layer is added.

[0033] Figure 4 It is shown in Figure 3 A cross-sectional view of a display device in which the shape of the upper surface of the hole injection layer is deformed.

[0034] Figure 5 It is shown in Figure 1 A cross-sectional view of a display device in which an electron transport layer is added.

[0035] Figure 6 It is shown in Figure 5 A cross-sectional view of a display device in which the shape of the upper surface of the hole injection layer is deformed.

[0036] Figure 7 It is shown in Figure 1 A cross-sectional view of a display device with an added hole transport layer and an electron transport layer.

[0037] Figure 8 It is shown in Figure 7 A cross-sectional view of a display device in which the shape of the upper surface of the hole injection layer is deformed.

[0038] Figure 9 and Figure 10 It is a cross-sectional view used to illustrate the horizontal distance between the curvature portions of the light-emitting layer and the hole injection layer.

[0039] Figure 11 and Figure 12 It is a cross-sectional view used to show the positional relationship between the fixed points of the light-emitting layer and the hole injection layer.

[0040] Figure 13 and Figure 14 It is a cross-sectional view used to show the curvature of the curvature portions of the light-emitting layer and the hole injection layer, respectively.

[0041] Symbol Explanation

[0042] 10: Substrate 100: Pixel Definition Film

[0043] 110: First electrode; 120, 120a: Hole injection layer

[0044] 130: Emissive layer; 140: Electron injection layer

[0045] 150: Second electrode; 160: Encapsulation layer

[0046] 170: Hole transport layer; 180: Electron transport layer

[0047] L120, L120a: Upper surface of the hole injection layer

[0048] L130: Upper surface of the light-emitting layer

[0049] P1, P10: Center points of the radius of curvature of the curvature portion of the hole injection layer

[0050] P2: The center point of the radius of curvature of the curvature portion of the light-emitting layer.

[0051] R1, R3: Radius of curvature of the curvature portion of the hole injection layer

[0052] R2: Radius of curvature of the curvature portion of the light-emitting layer

[0053] P3, P8: First fixed point; P4: Second fixed point

[0054] D1: The horizontal distance from the first fixed point to the central flat portion in the "U"-shaped cavity injection layer.

[0055] D2: The horizontal distance from the second fixed point to the central flat area within the "U"-shaped light-emitting layer.

[0056] D3: The horizontal distance from the first fixed point to the central flat portion in the "W"-shaped cavity injection layer.

[0057] D4: The vertical distance from the second fixed point to the upper surface of the first electrode in the "U"-shaped light-emitting layer.

[0058] D5: The vertical distance from the first fixed point to the upper surface of the first electrode in the "U"-shaped hole injection layer.

[0059] D6: Vertical distance from the first fixed point to the upper surface of the first electrode in the "W"-shaped hole injection layer. Detailed Implementation

[0060] Hereinafter, with reference to the accompanying drawings, a display device according to an embodiment of the present invention will be described in more detail.

[0061] Figure 1 This is a cross-sectional view showing a display device according to an embodiment of the present invention.

[0062] Reference Figure 1The display device may include a substrate 10, a pixel definition film 100, a first electrode 110, a hole injection layer 120, a light-emitting layer 130, an electron injection layer 140, a second electrode 150, and an encapsulation layer 160.

[0063] Substrate 10 may include an insulating substrate. The insulating substrate may include a transparent glass material with transparent SiO2 as its main component. In one embodiment, the insulating substrate may include a non-transparent material. The insulating substrate may also include a plastic material. In one embodiment, the insulating substrate may be a flexible substrate.

[0064] The display device may further include other structures formed on the substrate 10. These other structures may include, for example, wiring, electrodes, insulating films, etc. In one embodiment, the display device may include a plurality of thin-film transistors formed on the substrate 10. At least one of the plurality of thin-film transistors may be electrically connected to the first electrode 110. The thin-film transistor may include an active layer formed using amorphous silicon, polycrystalline silicon, or monocrystalline silicon. In one embodiment, the thin-film transistor may also include an active layer formed using oxide semiconductors.

[0065] The active layer may include a channel region. A source electrode and a drain electrode may be disposed at each end of the channel region. The source electrode and the drain electrode may be formed as a single layer or multiple layers of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu) or their alloys. The display device may further include a protective film overlapping the active layer, the source electrode, and the drain electrode. The protective film serves to prevent scratches or moisture penetration during the manufacturing process. The protective film may be formed using an inorganic film, such as a silicon oxide film (SiO2). x ), silicon nitride film (SiN) x The protective film may be formed by chemical vapor deposition (CVD) or by forming a multilayer film thereof.

[0066] A gate electrode for regulating the current in the channel region may be disposed at the upper part of the channel region. The gate electrode may be formed as a single layer or multiple layers of any one of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or their alloys. A gate insulating film may be disposed between the channel region and the gate electrode. The gate insulating film separates the channel region from the gate electrode. The gate insulating film may be an inorganic film, such as a silicon oxide film (SiO2). x ), silicon nitride film (SiN) x(or its multilayer film formation.)

[0067] The first electrode 110 can be used as a transparent electrode, a reflective electrode, or a semi-transparent electrode. When the first electrode 110 is used as a transparent electrode, it may include indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or In₂O₃. When the first electrode 110 is used as a reflective electrode, it may include a reflective film formed using Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and mixtures thereof, or a transmissive film formed using ITO, IZO, ZnO, or In₂O₃. When the first electrode 110 is used as a semi-transparent electrode, it may include a reflective film formed using Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and mixtures thereof, or a transmissive film formed using ITO, IZO, ZnO, or In₂O₃. The first electrode 110 can be formed by photolithography, but is not limited to this method.

[0068] When the first electrode 110 is used as a transparent electrode, the display device can be a back-emitting type where light generated from the light-emitting layer 130 is emitted towards the first electrode 110. Furthermore, when the first electrode 110 is used as a reflective electrode, the display device can be a front-emitting type where light generated from the light-emitting layer 130 is emitted towards the second electrode 150. Also, when the first electrode 110 is used as a semi-transparent electrode, the display device can be a back-emitting type where light generated from the light-emitting layer 130 is emitted towards the first electrode 110, and it has a resonant structure.

[0069] The pixel definition film 100 can cover the side portion of the first electrode 110 and is disposed on the substrate 10. The pixel definition film 100 can have an opening that exposes the upper surface of the first electrode 110. The side portion of the pixel definition film 100 can have an inclined shape.

[0070] A hole injection layer 120, a light-emitting layer 130, an electron injection layer 140, a second electrode 150, an encapsulation layer 160, etc., may be disposed on the first electrode 110 exposed through the opening of the pixel defining film 100. The pixel defining film 100 may include an insulating material. For example, the pixel defining film 100 may include at least one organic material selected from benzocyclobutene (BCB), polyimide (PI), polyamide (PA), acrylic resin, and phenolic resin. As another example, the pixel defining film 100 may also include an inorganic material such as silicon nitride.

[0071] The hole injection layer 120 can act as a buffer material to lower the energy barrier between the first electrode 110 and the light-emitting layer 130. The hole injection layer 120 can easily inject holes provided by the first electrode 110 into the light-emitting layer 130. The hole injection layer 120 may include organic compounds such as MTDATA (4,4',4"-tris(3-methylphenylphenylamino)triphenylamine), copper phthalocyanine (CuPc), or PEDOT / PSS (poly(3,4-ethylenedioxythiphene) / polystyrene sulfonate), etc.

[0072] The thickness of the hole injection layer 120 can increase from the flat portion in the center of the hole injection layer 120 towards the pixel definition film 100.

[0073] In one embodiment, the ink repellency of the hole injection layer 120 to the pixel definition film 100 can be greater than that of the light-emitting layer 130 to the pixel definition film 100. Therefore, the ink applied during the formation of the hole injection layer 120 may have lower surface adhesion to the pixel definition film 100, while the ink applied during the formation of the light-emitting layer 130 may have higher surface adhesion. Consequently, the distance between the first fixing point P3 and the second fixing point P4 can be increased.

[0074] The light-emitting layer 130 can be disposed within the pixel-defining film 100 on the hole injection layer 120. The light-emitting layer 130 can cause holes provided from the first electrode 110 to recombine with electrons provided from the second electrode 150 to emit light. More specifically, if the holes and electrons are provided to the light-emitting layer 130, they can recombine to form excitons. The excitons transition from an excited state to a ground state, thereby emitting energy in the form of light.

[0075] The luminescent layer 130 may, for example, include a red luminescent layer that emits red light. The red luminescent layer may include a red luminescent material, or may be formed by including a host and a red dopant. The host of the red luminescent layer may, for example, be Alq3, CBP (4,4'-N,N'-dicarbazol-biphenyl), PVK (poly(N-vinylcarbazole), ADN (9,10-di(naphthyl-2-yl)anthracene), TCTA, TPBI (1,3,5- Tris(N-phenylbenzimidazol-2-yl)benzene, TBADN (3-tert-butyl-9,10-di(naphth-2-yl)anthracene), E3, DSA (distyrylarylene), etc., but are not limited to these. Furthermore, the red dopant can be, for example, PtOEP, Ir(piq)3, Btp2Ir(acac), etc., but is not limited to these.

[0076] The light-emitting layer 130 may, for example, include a green light-emitting layer that emits green light. The green light-emitting layer may include a green light-emitting material, or it may include a substrate and a green dopant. The substrate of the green light-emitting layer may be the same as the substrate of the red light-emitting layer. Furthermore, the green dopant may be, for example, Ir(ppy)3, Ir(ppy)2(acac), Ir(mpyp)3, etc., and is not limited to these.

[0077] The light-emitting layer 130 may, for example, include a blue light-emitting layer that emits blue light. The blue light-emitting layer may include a blue light-emitting material, or may be formed by including a host and a blue dopant. The host of the blue light-emitting layer may be the same as the host of the red light-emitting layer. Furthermore, the blue dopant may be, for example, F₂Irpic, (F₂ppy)₂Ir(tmd), Ir(dfppz)₃, ter-fluorene, DPAVBi(4,4'-bis(4-diphenylaminostyryl)biphenyl), TBPe(2,5,8,11-tetra-tert-butyl pherylene), etc., and is not limited to these.

[0078] The wavelength of the red light can be approximately 650 nm, the wavelength of the green light is approximately 550 nm, and the wavelength of the blue light is approximately 430 nm.

[0079] The thickness of the light-emitting layer 130 can be thinner from the flat portion of the light-emitting layer 130 toward the pixel definition film 100.

[0080] An electron injection layer 140 can be disposed on the light-emitting layer 130. The electron injection layer 140 can act as a buffer material to lower the energy barrier between the light-emitting layer 130 and the second electrode 150. The electron injection layer 140 allows electrons supplied from the second electrode 150 to be easily injected into the light-emitting layer 130. The electron injection layer 140 can be formed using, for example, LiF or CsF, and is not limited thereto. The electron injection layer 140 can be formed by deposition methods, and is not limited thereto.

[0081] The thickness of the electron injection layer 140 can be thinner from the flat portion in the center of the electron injection layer 140 toward the pixel definition film 100.

[0082] The second electrode 150 can be disposed on the electron injection layer 140 and is a cathode electrode that provides electrons to the light-emitting layer 130. The second electrode 150 can be used as a transparent electrode, a reflective electrode, or a transmissive electrode. When the second electrode 150 is used as a transparent electrode, the display device can be a front-emitting type where light generated from the light-emitting layer 130 is emitted towards the second electrode 150. Furthermore, when the second electrode 150 is used as a reflective electrode, the display device can be a back-emitting type where light generated from the light-emitting layer 130 is emitted towards the first electrode 110. Furthermore, when the second electrode 150 is used as a transmissive electrode, the display device can be a front-emitting type where light generated from the light-emitting layer 130 is emitted towards the second electrode 150, and it is a resonant structure. The second electrode 150 can be formed by deposition methods, etc., and is not limited thereto.

[0083] The encapsulation layer 160 prevents external oxygen or moisture from penetrating into the organic light-emitting diode (OLED). In this case, when the encapsulation layer 160 is formed as a single layer, external impurities may still penetrate through it; therefore, the encapsulation layer 160 preferably has a multilayer film structure. When the encapsulation layer 160 is formed using only organic or inorganic films, oxygen or moisture may penetrate from the outside through fine pathways formed inside the encapsulation layer 160. Therefore, to prevent the formation of interconnected fine pathways from inside the encapsulation layer 160 to the OLED, the encapsulation layer 160 can have a layered structure with alternating layers of organic and inorganic films.

[0084] Furthermore, when forming the encapsulation layer 160, it is preferable that the outermost layer of the encapsulation layer 160 is an inorganic film made of a material such as silicon nitride and / or silicon oxide. This is because inorganic films have higher mechanical strength compared to organic films.

[0085] In this embodiment, the first fixing point P3 can be defined as the point where the side of the upper surface of the hole injection layer 120 intersects with the pixel definition film 100. The second fixing point P4 can be defined as the point where the side of the upper surface of the light-emitting layer 130 intersects with the pixel definition film 100. The shortest distance between the first fixing point P3 and the second fixing point P4 can be greater than or equal to the dielectric breakdown limit distance of the light-emitting layer 130. More specifically, the straight-line distance from the second fixing point P4 to the upper surface of the first electrode 110 can be greater than the straight-line distance from the first fixing point P3 to the upper surface of the first electrode 110 by an amount equivalent to or greater than the dielectric breakdown limit distance of the light-emitting layer 130 at a predetermined voltage.

[0086] The dielectric breakdown limit distance can be expressed as the minimum distance between the light-emitting layer 130 and the layer arranged below the light-emitting layer 130 for insulating the layer arranged below the light-emitting layer 130 from the light-emitting layer 130 under the predetermined voltage.

[0087] If the points where the pixel definition film 100 intersects with the upper surface of the hole injection layer 120, the upper surface of the pixel definition film 100 intersects with the upper surface of the light-emitting layer 130, and the upper surface of the pixel definition film 100 intersects with the upper surface of the electron injection layer 140 are in contact with or close to a thickness below a reference thickness, current leakage may occur. To prevent this, the hole injection layer 120, the light-emitting layer 130, and the electron injection layer 140 can each have various shapes.

[0088] In this embodiment, the upper surfaces of the hole injection layer 120, the light-emitting layer 130, and the electron injection layer 140 can each be curved towards the second electrode 150 to form a "U" shape. This prevents current leakage. The height of the central flat portion of the upper surface of the hole injection layer 120 can be lower than the height of the highest point of the side portion of the upper surface of the hole injection layer 120. The height of the central flat portion of the upper surface of the light-emitting layer 130 can be lower than the height of the highest point of the side portion of the upper surface of the light-emitting layer 130. The height of the central flat portion of the upper surface of the electron injection layer 140 can be lower than the height of the highest point of the side portion of the upper surface of the electron injection layer 140. Furthermore, the width of the central flat portion of the upper surface of the hole injection layer 120 can be greater than the width of the side portion of the upper surface of the hole injection layer 120. The width of the central flat portion of the upper surface of the light-emitting layer 130 can be greater than the width of the side portion of the upper surface of the light-emitting layer 130. The width of the flat portion at the center of the upper surface of the electron injection layer 140 can be greater than the width of the side portion of the upper surface of the electron injection layer 140.

[0089] The first fixed point P3 and the second fixed point P4 may not intersect each other. Since the upper surfaces of the hole injection layer 120, the light-emitting layer 130 and the electron injection layer 140 are each configured in a "U" shape, the points where the upper surfaces of the hole injection layer 120, the light-emitting layer 130 and the electron injection layer 140 intersect with the pixel definition film 100 are separated from each other, thereby preventing current leakage.

[0090] Figure 2 It is shown in Figure 1 A cross-sectional view of a display device in which the upper surface of the hole injection layer 120a is deformed.

[0091] In addition to the morphology of the upper surface of the hole injection layer 120a, Figure 2 Display device and Figure 1 The display devices are substantially the same or similar. Therefore, the explanation regarding the repetitive configuration is omitted.

[0092] Reference Figure 2 The upper surface of the hole injection layer 120a may have a first fixed point P8 that contacts the pixel definition film 100. The first fixed point P8 may be the highest point of the upper surface of the hole injection layer 120a. The upper surface of the hole injection layer 120a may have a lowest point P9. The upper surface of the hole injection layer 120a may have a starting point P7 for a central flat portion. The height of the starting point P7 may be lower than the height of the first fixed point P8 and higher than the height of the lowest point P9. The upper surface of the hole injection layer 120a may be formed in a "W" shape, with the width of the central flat portion being greater than the width of the curved portions on both sides of the upper surface of the hole injection layer 120a.

[0093] The display device can undergo a drying process. During the drying process, the height of the central flat portion on the upper surface of each of the hole injection layer 120a, the light-emitting layer 130, and the electron injection layer 140 may decrease. In this case, the thickness of the central flat portion in the vertical direction may become narrower. When the hole injection layer 120a is formed in a "W" shape, the height of the central flat portion on the upper surface of the hole injection layer 120a may decrease slightly less than the height of the central flat portion on the upper surface of a conventional "U"-shaped hole injection layer. Therefore, the height of the central flat portion on the upper surface of each of the light-emitting layer 130 and the electron injection layer 140 may also decrease slightly less than the conventional height.

[0094] The second fixing point P4 can be the point where the side of the upper surface of the light-emitting layer 130 intersects with the pixel definition film 100. The first fixing point P8 and the second fixing point P4 may not intersect each other. The upper surface of the hole injection layer 120a can be formed in a "W" shape, and the upper surfaces of the light-emitting layer 130 and the electron injection layer 140 can each be formed in a "U" shape. Therefore, the points where the upper surfaces of the hole injection layer 120a, the light-emitting layer 130, and the electron injection layer 140 intersect with the pixel definition film 100 are separated from each other, thereby preventing current leakage.

[0095] Figure 3 It is shown in Figure 1 A cross-sectional view of a display device with an added hole transport layer 170.

[0096] In addition to the hole transport layer 170 added between the hole injection layer 120 and the light emission layer 130, Figure 3 Display device and Figure 1 The display devices are substantially the same or similar. Therefore, the explanation regarding the repetitive configuration is omitted.

[0097] Reference Figure 3 The hole transport layer 170 serves to transfer holes received through the hole injection layer 120 to the light-emitting layer 130. The hole transport layer 170 can be formed using a hole transport material with a lower conductivity than the hole injection layer 120. The hole transport layer 170 can be formed using organic compounds, such as TPD (N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine) or NPB (N,N'-di(naphthalen-1-yl)-N,N'-diphenyl-benzidine), and is not limited to these.

[0098] The first fixing point P3 can be the point where the side of the upper surface of the hole injection layer 120 intersects with the pixel definition film 100. The second fixing point P4 can be the point where the side of the upper surface of the light-emitting layer 130 intersects with the pixel definition film 100. The first fixing point P3 and the second fixing point P4 may not intersect each other. The upper surfaces of the hole injection layer 120, the light-emitting layer 130, the electron injection layer 140, and the hole transport layer 170 are each configured in a "U" shape. Therefore, the points where the upper surfaces of the hole injection layer 120, the light-emitting layer 130, the electron injection layer 140, and the hole transport layer 170 intersect with the pixel definition film 100 are separated from each other, thereby preventing current leakage.

[0099] The thickness of the hole transport layer 170 can be thinner from the flat portion in the center of the hole transport layer 170 toward the pixel definition film 100.

[0100] In one embodiment, the ink repellency of the hole injection layer 120 to the pixel definition film 100 can be greater than that of the hole transport layer 170 to the pixel definition film 100.

[0101] Figure 4 It is shown in Figure 3 A cross-sectional view of a display device in which the upper surface of the hole injection layer 120a is deformed.

[0102] In addition to the morphology of the upper surface of the hole injection layer 120a, Figure 4 Display device and Figure 3 The display devices are substantially the same or similar. Therefore, the explanation regarding the repetitive configuration is omitted.

[0103] Reference Figure 4 The upper surface of the hole injection layer 120a may have a first fixed point P8 that contacts the pixel definition film 100. The first fixed point P8 may be the highest point of the upper surface of the hole injection layer 120a. The upper surface of the hole injection layer 120a may have a lowest point P9. The upper surface of the hole injection layer 120a may have a starting point P7 of a flat portion located in the center between the height of the first fixed point P8 and the height of the lowest point P9. The upper surface of the hole injection layer 120a may be formed in a "W" shape, where the width of the central flat portion is greater than the width of the curved portions on both sides of the upper surface of the hole injection layer 120a.

[0104] The display device can undergo a drying process. During the drying process, the height of the central flat portion on the upper surface of each of the hole injection layer 120a, the light-emitting layer 130, the electron injection layer 140, and the hole transport layer 170 may decrease. In this case, the thickness of the central flat portion in the vertical direction may become narrower. When the hole injection layer 120a is formed in a "W" shape, the height of the central flat portion on the upper surface of the hole injection layer 120a may decrease slightly less than the height of the central flat portion on the upper surface of a conventional "U"-shaped hole injection layer. Therefore, the height of the central flat portion on the upper surface of each of the light-emitting layer 130, the electron injection layer 140, and the hole transport layer 170 may also decrease slightly less than previously thought.

[0105] The second fixing point P4 can be the point where the side of the upper surface of the light-emitting layer 130 intersects with the pixel definition film 100. The first fixing point P8 and the second fixing point P4 may not intersect each other. The upper surface of the hole injection layer 120a can be formed in a "W" shape. The upper surfaces of the light-emitting layer 130, the electron injection layer 140, and the hole transport layer 170 can be formed in a "U" shape. Therefore, the points where the upper surfaces of the hole injection layer 120a, the light-emitting layer 130, and the electron injection layer 140 intersect with the pixel definition film 100 are separated from each other, thereby preventing current leakage.

[0106] Figure 5 It is shown in Figure 1 A cross-sectional view of a display device with an additional electron transmission layer 180.

[0107] In addition to the electron transport layer 180 added between the light-emitting layer 130 and the electron injection layer 140, Figure 5 Display device and Figure 1 The display devices are substantially the same or similar. Therefore, the explanation regarding the repetitive configuration is omitted.

[0108] Reference Figure 5 An electron transport layer 180 may be disposed on the light-emitting layer 130. The electron transport layer 180 can transfer electrons received from the second electrode 150 through the electron injection layer 140 to the light-emitting layer 130. The electron transport layer 180 may be formed using organic compounds. For example, organic compounds may include, but are not limited to, Bphen (4,7-diphenyl-1,10-phenanthroline), BAlq, Alq3 (tris(8-quinolinorate)aluminum), Bebq2 (berylliumbis(benzoquinolin-10-olate)), TPBI, etc. The electron transport layer 180 may be formed by deposition methods, etc., and is not limited to these methods.

[0109] The first fixed point P3 and the second fixed point P4 may not intersect each other. The upper surfaces of the hole injection layer 120, the light-emitting layer 130, the electron injection layer 140, and the electron transport layer 180 may each be configured in a "U" shape. Therefore, the points where the upper surfaces of the hole injection layer 120, the light-emitting layer 130, the electron injection layer 140, and the electron transport layer 180 intersect with the pixel definition film 100 are separated from each other, thereby preventing current leakage.

[0110] The thickness of the electron transport layer 180 can be thinner from the flat portion in the center of the electron transport layer 180 toward the pixel definition film 100.

[0111] Figure 6 It is shown in Figure 5 A cross-sectional view of a display device in which the upper surface of the hole injection layer 120a is deformed.

[0112] In addition to the morphology of the upper surface of the hole injection layer 120a, Figure 6 Display device and Figure 5 The display devices are substantially the same or similar. Therefore, the explanation regarding the repetitive configuration is omitted.

[0113] Reference Figure 6 The upper surface of the hole injection layer 120a may have a first fixed point P8 that contacts the pixel definition film 100. The first fixed point P8 may be the highest point of the upper surface of the hole injection layer 120a. The upper surface of the hole injection layer 120a may have a lowest point P9. The upper surface of the hole injection layer 120a may have a starting point P7 of a flat portion located in the center between the height of the first fixed point P8 and the height of the lowest point P9. The upper surface of the hole injection layer 120a may be formed in a "W" shape, where the width of the central flat portion is greater than the width of the curved portions on both sides of the upper surface of the hole injection layer 120a.

[0114] The display device can undergo a drying process. During the drying process, the height of the central flat portion on the upper surface of each of the hole injection layer 120a, the light-emitting layer 130, the electron injection layer 140, and the electron transport layer 180 may decrease. In this case, the thickness of the central flat portion in the vertical direction may become narrower. When the upper surface of the hole injection layer 120a is formed in a "W" shape, the height of the central flat portion on the upper surface of the hole injection layer 120a may decrease by a slightly smaller degree than that of the central flat portion on the upper surface of a conventional "U"-shaped hole injection layer. Therefore, the height of the central flat portion on the upper surface of each of the light-emitting layer 130, the electron injection layer 140, and the electron transport layer 180 may also decrease by a slightly smaller degree than that of conventional layers.

[0115] The first fixed point P8 and the second fixed point P4 may not intersect each other. The upper surface of the hole injection layer 120a may be formed in a "W" shape. The upper surfaces of the light-emitting layer 130, the electron injection layer 140, and the electron transport layer 180 may be formed in a "U" shape. Therefore, the points where the upper surfaces of the hole injection layer 120a, the light-emitting layer 130, and the electron injection layer 140 intersect with the pixel definition film 100 are separated from each other, thereby preventing current leakage.

[0116] Figure 7 It is shown in Figure 1 A cross-sectional view of a display device with an additional hole transport layer 170 and an electron transport layer 180.

[0117] In addition to the addition of a hole transport layer 170 and an electron transport layer 180, Figure 7 Display device and Figure 1 The display devices are substantially the same or similar. Furthermore, refer to... Figure 1 , Figure 3 and Figure 5 able to master Figure 7 Therefore, the explanation regarding the repetitive structure is omitted.

[0118] Figure 8 It is shown in Figure 7 A cross-sectional view of a display device in which the upper surface of the hole injection layer 120a is deformed.

[0119] In addition to the morphology of the upper surface of the hole injection layer 120a, Figure 8 Display device and Figure 7 The display devices are substantially the same or similar. Therefore, the explanation regarding the repetitive configuration is omitted.

[0120] Figure 9 and Figure 10 It is a cross-sectional view used to illustrate the horizontal distance between the curvature portions of the light-emitting layer 130 and the hole injection layers 120 and 120a.

[0121] Figure 9 It can be shown in Figure 1 , Figure 3 , Figure 5 and Figure 7 The horizontal distance D1 between the first fixed point P3 where the side portion of the upper surface L120 of the hole injection layer 120 intersects with the pixel definition film 100 and the point P5 where the curved portion of the side portion of the upper surface L120 of the hole injection layer 120 intersects with the flat portion at the center of the upper surface L120 of the hole injection layer 120.

[0122] and, Figure 9 The horizontal distance D2 between the second fixed point P4 where the side portion of the upper surface L130 of the light-emitting layer 130 intersects with the pixel definition film 100 and the point P6 where the curved portion of the side portion of the upper surface L130 of the light-emitting layer 130 intersects with the flat portion in the center of the light-emitting layer 130 can be shown.

[0123] Reference Figure 9 The horizontal distance D2 between the second fixed point P4 and point P6 can be about 0.5 μm to about 3 μm, preferably about 0.5 μm.

[0124] Furthermore, the horizontal distance D1 between the first fixed point P3 and point P5 can be from about 0.5 μm to about 3 μm, preferably about 0.5 μm.

[0125] Accordingly, it can be ensured that the distance between the first fixing point P3 and the second fixing point P4 is greater than or equal to the dielectric breakdown limit distance in the region (e.g., both sides of the light-emitting layer 130), while ensuring the light-emitting region for the light-emitting layer 130 to emit light (e.g., the flat portion in the center of the light-emitting layer 130).

[0126] Figure 10 It can be shown in Figure 2 , Figure 4 , Figure 6 and Figure 8 The horizontal distance D3 between the first fixed point P8 where the side portion of the upper surface L120a of the hole injection layer 120a intersects with the pixel definition film 100 and the point P7 where the curved portion of the side portion of the upper surface L120a of the hole injection layer 120a intersects with the flat portion in the center of the hole injection layer 120a.

[0127] Reference Figure 10 The horizontal distance D2 between the second fixed point P4 and point P6 can be about 0.5 μm to about 3 μm, preferably about 0.5 μm.

[0128] Furthermore, the horizontal distance D3 between the first fixed point P8 and point P7 can be from about 0.5 μm to about 3 μm, preferably from about 0.5 μm.

[0129] Figure 11 and Figure 12 It is a cross-sectional view used to show the positional relationship of the fixing points of the light-emitting layer 130 and the hole injection layers 120, 120a.

[0130] Figure 11 It can be shown in Figure 1 , Figure 3 , Figure 5 and Figure 7 The vertical distance D5 between the first fixed point P3 where the side of the upper surface L120 of the hole injection layer 120 intersects with the pixel definition film 100 and the upper surface of the first electrode 110.

[0131] and, Figure 11 The vertical distance D4 from the second fixed point P4 where the upper surface L130 of the light-emitting layer 130 intersects with the pixel definition film 100 to the upper surface of the first electrode 110 can be shown.

[0132] The vertical distance D4 from the second fixed point P4 to the upper surface of the first electrode 110 can be larger than the vertical distance D5 from the first fixed point P3 to the upper surface of the first electrode 110, which is equivalent to or greater than the dielectric breakdown limit distance of the light-emitting layer 130 under a predetermined voltage.

[0133] Figure 12 It can be shown in Figure 2 ,Figure 4 , Figure 6 and Figure 8 The vertical distance D6 from the first fixed point P8 where the side of the upper surface L120a of the hole injection layer 120a intersects with the pixel definition film 100 to the upper surface of the first electrode 110.

[0134] and, Figure 12 The vertical distance D4 from the second fixed point P4 where the upper surface L130 of the light-emitting layer 130 intersects with the pixel definition film 100 to the upper surface of the first electrode 110 can be shown.

[0135] The vertical distance D4 can be larger than the vertical distance D6 by an amount equivalent to or greater than the dielectric breakdown limit distance of the light-emitting layer 130 at a predetermined voltage.

[0136] Figure 13 and Figure 14 It is a cross-sectional view used to show the curvature of the curvature portion of the light-emitting layer 130 and the hole injection layers 120, 120a respectively.

[0137] Figure 13 It can be used to show in Figure 1 , Figure 3 , Figure 5 and Figure 7 A cross-sectional view showing the relationship between the first fixed point P3 where the side of the upper surface L120 of the hole injection layer 120 intersects with the pixel definition film 100 and the second fixed point P4 where the side of the upper surface L130 of the light-emitting layer 130 intersects with the pixel definition film 100.

[0138] If a virtual circle is drawn representing the curvature of the side portion of the upper surface L130 of the light-emitting layer 130, a circle with a center point P2 and a radius of curvature R2 can be formed. If a virtual circle is drawn representing the curvature of the side portion of the upper surface L120 of the hole injection layer 120, a circle with a center point P1 and a radius of curvature R1 can be formed. The radius of curvature R2 can be less than or equal to the radius of curvature R1.

[0139] With the curvature radius relationship as described above, a distance difference can be generated between the second fixed point P4 and the first fixed point P3, thereby preventing current leakage.

[0140] Figure 14 It can be used to show in Figure 2 , Figure 4 , Figure 6 and Figure 8 A cross-sectional view showing the relationship between the first fixed point P8 where the side of the upper surface L120a of the hole injection layer 120a intersects with the pixel definition film 100 and the second fixed point P4 where the side of the upper surface L130 of the light-emitting layer 130 intersects with the pixel definition film 100.

[0141] If a virtual circle is drawn representing the curvature of the side portion of the upper surface L130 of the light-emitting layer 130, a circle with a center point P2 and a radius of curvature R2 can be formed. If a virtual circle is drawn representing the curvature of the side portion of the upper surface L120a of the hole injection layer 120a, a circle with a center point P10 and a radius of curvature R3 can be formed. The radius of curvature R2 can be less than or equal to the radius of curvature R3.

[0142] With the curvature radius relationship as described above, a distance difference can be generated between the second fixed point P4 and the first fixed point P8, thereby preventing current leakage.

[0143] While embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art will understand that other specific forms can be implemented without altering the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood in all respects as illustrative and not limiting.

[0144] Industrial availability

[0145] This invention can be applied to display devices and a variety of electronic devices including such display devices. For example, this invention can be applied to portable telephones, smartphones, video phones, smart tablets, smartwatches, tablet PCs, vehicle navigation systems, televisions, computer monitors, laptops, head-mounted displays, etc.

[0146] Although the above description has been made with reference to exemplary embodiments of the present invention, it will be understood by those skilled in the art that various modifications and alterations can be made to the present invention without departing from the spirit and scope of the invention as set forth in the claims.

Claims

1. A display device, comprising: substrate; A first electrode is disposed on the substrate; A pixel-defining film exposes the upper surface of the first electrode and covers the sides of the first electrode; The second electrode is disposed on the first electrode; A hole injection layer is disposed between the first electrode and the second electrode, and has an upper surface that protrudes laterally toward the second electrode; A light-emitting layer is disposed between the hole injection layer and the second electrode, and has an upper surface that protrudes laterally toward the second electrode; as well as An electron injection layer is disposed between the light-emitting layer and the second electrode. Wherein, the shortest distance between the first fixed point at the junction of the side portion of the upper surface of the hole injection layer and the pixel definition film, and the second fixed point at the junction of the side portion of the upper surface of the light-emitting layer and the pixel definition film, is greater than or equal to the dielectric breakdown limit distance of the light-emitting layer. The radius of curvature of the side portion of the upper surface of the hole injection layer is greater than the radius of curvature of the side portion of the upper surface of the light-emitting layer.

2. The display device according to claim 1, characterized in that, Also includes: A hole transport layer is disposed between the hole injection layer and the light-emitting layer. The hole injection layer has a greater ink repellency to the pixel definition film than the hole transport layer does to the pixel definition film.

3. The display device according to claim 1, characterized in that, Also includes: An electron transport layer is disposed between the light-emitting layer and the electron injection layer.

4. The display device according to claim 1, characterized in that, The horizontal distance from the first fixed point to the point where the flat portion at the center of the upper surface of the hole injection layer intersects with the curved portion of the side portion of the upper surface of the hole injection layer is 0.5 μm to 3 μm.

5. The display device according to claim 1, characterized in that, The horizontal distance from the second fixed point to the point where the flat portion at the center of the upper surface of the light-emitting layer intersects with the curved portion of the side portion of the upper surface of the light-emitting layer is 0.5 μm to 3 μm.

6. The display device according to claim 1, characterized in that, The hole injection layer has a greater ink repellency to the pixel definition film than the light-emitting layer does to the pixel definition film.

7. The display device according to claim 1, characterized in that, The upper surface of the hole injection layer has a "U" shape.

8. The display device according to claim 7, characterized in that, The upper surface of the hole injection layer has a flat portion whose width is greater than the width of the side portion of the upper surface of the hole injection layer.

9. The display device according to claim 1, characterized in that, The upper surface of the hole injection layer has a "W" shape.

10. The display device according to claim 9, characterized in that, The height of the flat portion at the center of the upper surface of the hole injection layer is lower than the height of the first fixed point, the height of the flat portion at the center of the upper surface of the hole injection layer is higher than the height of the lowest point of the curvature portion of the side portion of the upper surface of the hole injection layer, and the width of the flat portion of the upper surface of the hole injection layer is greater than the width of the side portion of the upper surface of the hole injection layer.

11. The display device according to claim 1, characterized in that, The upper surface of the light-emitting layer has a "U" shape.

12. The display device according to claim 11, characterized in that, The width of the flat portion at the center of the upper surface of the light-emitting layer is greater than the width of the side portion of the upper surface of the light-emitting layer.

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