Display device

Abstract

To provide a display device with improved display quality.SOLUTION: A display device includes a plurality of pixels including a first pixel for emitting red light, a second pixel for emitting green light, and a third pixel for emitting blue light. Each of the pixels includes an anode including a reflection electrode and a transparent electrode on a substrate, an organic EL layer provided on the anode, a protection layer provided covering a side surface of the organic EL layer, and a cathode provided in an opening of the protection layer and a bank and provided in contact with the organic EL layer. A first anode of the first pixel includes a first reflection electrode and a first transparent electrode. A second anode of the second pixel includes a second reflection electrode and a second transparent electrode. A third anode of the third pixel includes a third reflection electrode and a third transparent electrode. A first thickness of the first transparent electrode, a second thickness of the second transparent electrode, and a third thickness of the third transparent electrode are smaller in this order.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to a display device.

Background Art

[0002] An organic electroluminescence (organic EL) display device that obtains light emission by utilizing the energy at the time of recombination of holes injected from an anode and electrons injected from a cathode has been developed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present embodiment is to provide a display device with improved display quality.

Means for Solving the Problems

[0005] A display device according to an embodiment includes a plurality of pixels including a first pixel that emits red light, a second pixel that emits green light, and a third pixel that emits blue light, a bank provided between adjacent pixels, and is provided with each of the plurality of pixels includes on a substrate, an anode including a reflective electrode and a transparent electrode, an organic EL layer provided on the anode, a protective layer provided so as to cover a side surface of the organic EL layer, a cathode provided in an opening of the protective layer and the bank and provided in contact with the organic EL layer, comprising The first anode of the first pixel includes a first reflective electrode and a first transparent electrode. The second anode of the second pixel includes a second reflective electrode and a second transparent electrode. The third anode of the third pixel includes a third reflective electrode and a third transparent electrode. The first thickness of the first transparent electrode, the second thickness of the second transparent electrode, and the third thickness of the third transparent electrode are successively thinner.

Brief Description of the Drawings

[0006]

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DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Note that the disclosure is merely an example, and those that can be easily conceived by those skilled in the art with appropriate modifications while maintaining the gist of the invention are naturally included in the scope of the present invention. Also, for the purpose of making the description clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect, but this is merely an example and does not limit the interpretation of the present invention. Further, in this specification and each figure, elements that are the same as those described above with respect to the previously shown figures may be given the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0008] The embodiments described in this specification are not general ones, but are embodiments that explain the same or corresponding special technical features of the present invention. Hereinafter, a display device according to an embodiment will be described in detail with reference to the drawings.

[0009] In this embodiment, the first direction X, the second direction Y, and the third direction Z are orthogonal to each other, but they may intersect at an angle other than 90 degrees. The direction toward the tip of the arrow in the third direction Z is defined as up or upward, and the direction opposite to the direction toward the tip of the arrow in the third direction Z is defined as down or downward. Note that the first direction X, the second direction Y, and the third direction Z may also be referred to as the X direction, the Y direction, and the Z direction, respectively.

[0010] Also, when referring to "the second member above the first member" and "the second member below the first member", the second member may be in contact with the first member or may be located away from the first member. In the latter case, a third member may be interposed between the first member and the second member. On the other hand, when referring to "the second member on the first member" and "the second member under the first member", the second member is in contact with the first member.

[0011] Also, it is assumed that there is an observation position for observing the display device on the tip side of the arrow in the third direction Z. Looking from this observation position toward the X-Y plane defined by the first direction X and the second direction Y is referred to as a plan view. Looking at a cross-section of the display device in the X-Z plane defined by the first direction X and the third direction Z, or in the Y-Z plane defined by the second direction Y and the third direction Z is referred to as a cross-sectional view.

[0012] [Embodiment 1] FIG. 1 is an overall perspective view of the display device of Embodiment 1. The display device DSP has a display area DA and a peripheral area FA provided around the display area DA on a substrate SUB1. The display device DSP has a plurality of pixels PX arranged in the display area DA. In the display device DSP, light LT from the back surface is transmitted to the front surface, and vice versa.

[0013] A substrate SUB2 as a sealing material is provided on the upper surface of the display area DA. The substrate SUB2 is fixed to the substrate SUB1 by a sealing material (non-display) surrounding the display area DA. The display area DA formed on the substrate SUB1 is sealed by the substrate SUB2 as a sealing material and the sealing material so as not to be exposed to the atmosphere.

[0014] An area EA at the end of the substrate SUB1 is disposed outside the substrate SUB2. A wiring substrate PCS is provided in the area EA. A driving element DRV for outputting a video signal and a driving signal is provided on the wiring substrate PCS. Signals from the driving element DRV are input to the pixels PX of the display area DA via the wiring substrate PCS. Based on the video signal and various control signals, the pixels PX emit light.

[0015] FIG. 2 is a partial plan view showing an example of a schematic configuration of a display device. The plurality of pixels PX include a pixel PXR that emits red light, a pixel PXG that emits green light, and a pixel PXB that emits blue light. The pixel PXR, the pixel PXG, and the pixel PXB are also referred to as a first pixel, a second pixel, and a third pixel, respectively. The pixel PXR is arranged adjacent to the pixel PXB along a first direction X and a second direction Y. The pixel PXG is arranged adjacent to the pixel PXB along the first direction X and the second direction Y. The pixel PXB is arranged adjacent to the pixel PXR along the first direction and adjacent to the pixel PXG along the second direction Y.

[0016] FIG. 3 is a cross-sectional view taken along line A1 - A2 of the display device shown in FIG. 2. The base material BA1 includes, for example, glass or a resin material composed of a resin material. As the resin material, for example, acrylic, polyimide, polyethylene terephthalate, polyethylene naphthalate, etc. may be used, and it may be formed by any single layer or a plurality of layers stacked.

[0017] An insulating layer UC1 is provided on the base material BA1. The insulating layer UC1 is formed by, for example, a single layer or a stack of a silicon oxide film and a silicon nitride film.

[0018] A light-shielding layer BM may be provided on the insulating layer UC1 so as to overlap with the transistor Tr. The light-shielding layer BM suppresses changes in transistor characteristics due to the intrusion of light from the back surface of the channel of the transistor Tr. When the light-shielding layer BM is formed of a conductive layer, it is also possible to give a back-gate effect to the transistor Tr by applying a predetermined potential.

[0019] An insulating layer UC2 is provided to cover the insulating layer UC1 and the light-shielding layer BM. As the material of the insulating layer UC2, the same material as that of the insulating layer UC1 can be used. The insulating layer UC2 may be a material different from that of the insulating layer UC1. For example, the insulating layer UC1 can use silicon oxide and the insulating layer UC2 can use silicon nitride. The insulating layers UC1 and UC2 are collectively referred to as the insulating layer UC.

[0020] A transistor Tr is provided on an insulating layer UC. The transistor Tr includes a semiconductor layer SC, an insulating layer GI, a gate electrode GE (scanning line), an insulating layer ILI, a source electrode SE (signal line), and a drain electrode DE.

[0021] As the semiconductor layer SC, amorphous silicon, polysilicon, or an oxide semiconductor is used. As the insulating layer GI, for example, silicon oxide or silicon nitride is provided as a single layer or a laminate.

[0022] As the gate electrode GE, for example, a molybdenum tungsten alloy (MoW) is used. The gate electrode GE may be integrally formed with a scanning line GL.

[0023] An insulating layer ILI is provided so as to cover the semiconductor layer SC and the gate electrode GE. The insulating layer ILI is formed, for example, by providing a single layer or a laminate of a silicon oxide layer or a silicon nitride layer.

[0024] A source electrode SE and a drain electrode DE are provided on the insulating layer ILI. The source electrode SE and the drain electrode DE are connected to a source region and a drain region of the semiconductor layer SC via contact holes provided in the insulating layer ILI and the insulating layer GI, respectively. The source electrode SE may be integrally formed with a signal line.

[0025] An insulating layer PAS is provided so as to cover the source electrode SE, the drain electrode DE, and the insulating layer ILI. An insulating layer PLL is provided so as to cover the insulating layer PAS.

[0026] The insulating layer PAS is formed using an inorganic insulating material. Examples of the inorganic insulating material include those formed by providing a single layer or a laminate of silicon oxide or silicon nitride. The insulating layer PLL is formed using an organic insulating material. Examples of the organic insulating material include organic materials such as photosensitive acrylic and polyimide. By providing the insulating layer PLL, the step difference due to the transistor Tr can be flattened.

[0027] An anode AD is provided on the insulating layer PLL. The anode AD is connected to the drain electrode DE through contact holes provided in the insulating layers PAS and PLL. Let the anode provided in the pixel PXR be the anode ADR, the anode provided in the pixel PXB be the anode ADB, and the anode provided in the pixel PXG be the anode ADG. When there is no need to distinguish between the anodes ADR, ADG, and ADB, they are simply referred to as the anode AD.

[0028] Details of the configuration and material of the anode AD will be described later. In this embodiment, the configuration from the base material BA1 to the insulating layer PLL is defined as the backplane BPS.

[0029] A bank BK (also referred to as a convex portion or a rib) is provided between adjacent anodes AD. As the material of the bank BK, an organic material similar to the material of the insulating layer PLL is used. The bank BK is opened so as to expose a part of the anode AD.

[0030] Let the opening provided in the pixel PXR be the opening OPR, the opening provided in the pixel PXB be the opening OPB, and the opening provided in the pixel PXG be the opening OPG. When there is no need to distinguish between the openings OPR, OPB, and OPG, they are simply referred to as the opening OP.

[0031] The end of the opening OP preferably has a gentle taper shape in a cross-sectional view. If the end of the opening OP has a steep shape, coverage defects will occur in the organic EL layer ELY formed later.

[0032] An organic EL layer ELY is provided between adjacent banks BK, overlapping the anode AD. Although details will be described later, the organic EL layer ELY includes an electron transport layer ETY, a light-emitting layer EML, a hole transport layer HTL, and a hole injection layer HIL. The organic EL layer ELY may further include an electron injection layer, an electron blocking layer, and a hole blocking layer if necessary.

[0033] The organic EL layer provided in pixel PXR is defined as organic EL layer ELYR, the organic EL layer provided in pixel PXB is defined as organic EL layer ELYB, and the organic EL layer provided in pixel PXG is defined as organic EL layer ELYG. When there is no need to distinguish between organic EL layer ELYR, organic EL layer ELYG, and organic EL layer ELYB, they are simply referred to as organic EL layer ELY.

[0034] A cathode CD is provided on the organic EL layer ELY. The cathode CD is formed using, for example, a magnesium-silver alloy (MgAg) film, a single-layer film of silver (Ag), a laminated film of silver (Ag) and a transparent conductive material, etc. As the transparent conductive material, for example, indium tin oxide (ITO), indium zinc oxide (IZO), etc. may be used.

[0035] An insulating layer SEY is provided to cover the cathode CD. The insulating layer SEY has a function of preventing moisture from entering the organic EL layer ELY from the outside. As the insulating layer SEY, those with high gas barrier properties are preferable. Examples of the insulating layer SEY include an insulating layer in which an organic insulating layer is sandwiched between two inorganic insulating layers containing nitrogen. Examples of the material of the organic insulating layer include acrylic resin, epoxy resin, polyimide resin, etc. Examples of the material of the inorganic insulating layer containing nitrogen include silicon nitride, aluminum nitride.

[0036] A substrate BA2 is provided on the insulating layer SEY. The substrate BA2 is formed of the same material as the substrate BA1. A light-transmissive inorganic insulating layer or organic insulating layer may be provided between the substrate BA2 and the insulating layer SEY. The organic insulating layer may have a function of adhering the insulating layer SEY and the substrate BA2.

[0037] The light emitted from the organic EL layer ELY is extracted upward through the cathode CD. That is, the display device DSP of this embodiment has a top emission structure.

[0038] FIG. 4 is a cross-sectional view showing an example of the schematic configuration of Embodiment 1. In the display device DSP shown in FIG. 4, only the configuration in the vicinity of the organic EL layer ELY is shown. In FIG. 4, an anode AD (anode ADR, anode ADG, anode ADB) is provided on the backplane BPS.

[0039] The anode AD has a reflective electrode RD and a transparent electrode TD. The reflective electrode RD and the transparent electrode TD are laminated in this order along the third direction Z.

[0040] The reflective electrode RD is formed using a conductive material with a high reflectivity, such as silver (Ag) or aluminum (Al). Alternatively, the reflective electrode RD may be formed using an aluminum (Al) alloy. In that case, the reflective electrode RD has a three-layer structure in which a barrier metal such as titanium (Ti) is laminated very thinly on aluminum (Al) or an aluminum alloy, and indium tin oxide (ITO) is further laminated. Materials that alloy with aluminum include neodymium (Nd), titanium (Ti), tantalum (Ta), lanthanum (La), etc. The transparent electrode TD is formed using, for example, indium zinc oxide (IZO).

[0041] The anode ADR has a reflective electrode RDR and a transparent electrode TDR. Let the length (thickness) of the transparent electrode TDR along the third direction Z be the thickness tr.

[0042] The anode ADG has a reflective electrode RDG and a transparent electrode TDG. Let the length (thickness) of the transparent electrode TDG along the third direction Z be the thickness tg.

[0043] The anode ADB has a reflective electrode RDB and a transparent electrode TDB. Let the length (thickness) of the transparent electrode TDB along the third direction Z be the thickness tb.

[0044] The thicknesses of the reflective electrodes RDR, RDG, and RDB are the same. On the other hand, the thickness tr of the transparent electrode TDR, the thickness tg of the transparent electrode TDG, and the thickness tb of the transparent electrode TDB are in this order thinner (tr > tg > tb). The thicknesses of the reflective electrodes RDR, RDG, and RDB are thicker than the thickness tr of the transparent electrode TDR, the thickness tg of the transparent electrode TDG, and the thickness tb of the transparent electrode TDB.

[0045] The thickness tr of the transparent electrode TDR, the thickness tg of the transparent electrode TDG, and the thickness tb of the transparent electrode TDB are proportional to the wavelengths of the light emitted by their respective pixels. Among the pixels PXR, PXG, and PXB, the pixel that emits light with the longest wavelength is the pixel PXR that emits red light. Conversely, among the pixels PXR, PXG, and PXB, the pixel that emits light with the shortest wavelength is the pixel PXB that emits blue light. If the wavelength of the light (red) emitted by the pixel PXR is the wavelength λr, the wavelength of the light (green) emitted by the pixel PXG is the wavelength λg, and the wavelength of the light (blue) emitted by the pixel PXB is the wavelength λb, then the relationship λr > λg > λb holds. The thicknesses of the transparent electrodes TDR, TDG, and TDB have the same magnitude relationship (tr > tg > tb) as the magnitude relationship of the wavelengths (λr > λg > λb) as described above.

[0046] As described above, by adjusting the thickness of the transparent electrode TD, it is also possible to adjust the optical path length from the reflective electrode RD to the light-emitting layer EML.

[0047] The extraction efficiency of the blue light emitted from the organic EL layer ELYB is lower than that of the red light and the green light. Further, when the thickness tb of the transparent electrode TDB is large, the blue light is absorbed. Therefore, when the thickness tb of the transparent electrode TDB is large, the amount of blue light emitted from the pixel PXB becomes smaller than that of the red light and the green light. Therefore, it is preferable that the thickness tb is thinner. The thickness tb is preferably about 20 nm. The thickness tg and the difference in the thickness tg are preferably about 10 nm, for example. Note that the difference in the thickness tg and the thickness tr is also preferably about 10 nm. That is, the thickness tb, the thickness tg, and the thickness tr are preferably 20 nm, 30 nm, and 40 nm, respectively. Further, when adjusting the optical path length, the thickness tb, the thickness tg, and the thickness tr may be 50 nm, 100 nm, and 150 nm, respectively.

[0048] When the thickness tr of the transparent electrode TDR is large, there are advantages in the manufacturing process, such as deposition tact. Further, the extraction efficiency of the red light emitted from the organic EL layer ELYR is high. Therefore, even when the thickness tr of the transparent electrode TDR is large and the light is absorbed by the transparent electrode TDR, the amount of red light emitted from the pixel PXR does not decrease as much as the blue light.

[0049] An organic EL layer ELY is provided on the anode AD. An organic EL layer ELYR is provided on the anode ADR. An organic EL layer ELYB is provided on the anode ADB. An organic EL layer ELYG is provided on the anode ADG.

[0050] A protective layer AOL is provided so as to cover the sides of the anode ADR, the anode ADG, the anode ADB, the organic EL layer ELYR, the organic EL layer ELYG, and the organic EL layer ELYB. The protective layer AOL is formed of, for example, aluminum oxide (AlOx).

[0051] A bank BK is provided on the protective layer AOL and also between adjacent organic EL layers ELY. An opening OP (opening OPR, opening OPB, opening OPG) is provided between adjacent banks BK. Although not shown in FIG. 4, a cathode CD is provided to cover the bank BK, the organic EL layer ELY, and the protective layer AOL.

[0052] FIG. 5 is a cross-sectional view showing an example of a schematic configuration of Embodiment 1. FIG. 5 is a partially enlarged view of FIG. 4. As shown in FIG. 5, an organic EL layer ELY is provided between the anode AD and the cathode CD along the third direction Z. The organic EL layer ELY includes a hole injection layer HIL, a hole transport layer HTL, a light emitting layer EML, an electron transport layer ETL, and an electron injection layer EIL, which are stacked along the third direction Z. The anode AD is a laminate of a reflective electrode RD and a transparent electrode TD.

[0053] FIGS. 6 to 21 are cross-sectional views showing a method of manufacturing the display device of Embodiment 1. In FIGS. 6 to 21, a first pixel, which is one of the pixels PXR, PXG, and PXB, is defined as pixel PX1, and another second pixel is defined as pixel PX2. In FIGS. 6 to 21, the first pixel (pixel PX1) and the second pixel (pixel PX2) are formed in this order. Although not shown, a third pixel (referred to as pixel PX3), which is another one of the pixels PXR, PXG, and PXB, is formed in the same manner as the first pixel and the second pixel.

[0054] First, an anode AD1 and an anode AD2 are formed on a substrate BA1 (see FIG. 6). The anode AD1 is the anode of the pixel PX1, and the anode AD2 is the anode of the pixel PX2. The anode AD1 has a reflective electrode RD1 and a transparent electrode TD1. The anode AD2 has a reflective electrode RD2 and a transparent electrode TD2.

[0055] Let the thickness of the transparent electrode TD1 in FIG. 6 be thickness t10, and the thickness of the transparent electrode TD2 be thickness t20. The thickness t10 is thicker than the thickness t20 (t10 > t20).

[0056] Cover the base material BA1, the anode AD1, and the anode AD2 to form the organic EL layer ELM1, the sacrificial layer AOM1, and the sacrificial layer MWM1 (see Figure 7). The organic EL layer ELM1 is the organic EL layer corresponding to the pixel PX1.

[0057] The sacrificial layer AOM1 is formed of, for example, aluminum oxide (AlOx). Aluminum oxide may be formed by atomic layer deposition (ALD).

[0058] The sacrificial layer MWM1 is formed of, for example, molybdenum tungsten (MoW). Molybdenum tungsten may be formed by sputtering.

[0059] Form a resist mask RES1 on the sacrificial layer MWM1 facing the anode AD1 (see Figure 8). No resist mask is formed on the anode AD2.

[0060] Using the resist mask RES1, partially remove the sacrificial layer MWM1 by etching. As a result, a sacrificial layer MWY1 is formed in an island shape between the anode AD1 with the sacrificial layer AOM1 interposed therebetween (see Figure 9).

[0061] Using the sacrificial layer MWY1 formed in an island shape as a mask, partially remove the sacrificial layer AOM1 and the organic EL layer ELM1 by etching. As a result, an organic EL layer ELY1 and an upper layer AOU1 of the sacrificial layer are formed in an island shape between the anode AD1 and the sacrificial layer MWY1 (see Figure 10). The sacrificial layer AOM1 and the organic EL layer ELM1 on the anode AD2 are removed.

[0062] Form a sidewall AOS1 in contact with the side surfaces of the anode AD1, the organic EL layer ELY1, the upper layer AOU1, and the sacrificial layer MWY1. The sidewall AOS1 is formed of the same material as the sacrificial layer AOM1. The upper layer AOU1 and the sidewall AOS1 are combined to form a sacrificial layer AOY1 (see Figure 11).

[0063] To form the sidewall AOS1, first, a material film that will become the sidewall AOS1 is formed to cover the laminate of the organic EL layer ELY1, the upper layer AOU1, and the sacrificial layer MWY1. Then, the material film is anisotropically etched to leave only the region in contact with the side surface of the laminate and remove other regions.

[0064] During anisotropic etching, the transparent electrode TD2 of the anode AD2 may be etched. Both the material film that will become the sidewall AOS1 and the transparent electrode TD2 are formed of a material containing a metal oxide. When etching such a metal oxide, it may be necessary to use an etching gas with no selectivity. If an etching gas with no selectivity is used, as described above, the transparent electrode TD2 may be etched, resulting in the disappearance of the transparent electrode TD2 or a reduction in the film thickness of the transparent electrode TD2.

[0065] Let the thickness of the transparent electrode TD1 in FIG. 11 be thickness t11 and the thickness of the transparent electrode TD2 be thickness t21. By making the thickness t20 in FIG. 6 sufficient, even if the transparent electrode TD2 is etched by anisotropic etching in the process shown in FIG. 11, the transparent electrode TD2 will not disappear. The thickness of the transparent electrode TD2 decreases from thickness t20 to thickness t21 (t20 > t21).

[0066] The thickness t11 of the transparent electrode TD1 is thicker than the thickness t21 of the transparent electrode TD2 (t11 > t21). Since the organic EL layer ELY1, the upper layer AOU1 of the sacrificial layer AOY1, and the laminate of the sacrificial layer MWY1 are provided on the transparent electrode TD1, it is not etched by anisotropic etching. That is, the thickness t11 shown in FIG. 11 is the same as the thickness t10 shown in FIG. 6 (t11 = t10).

[0067] The organic EL layer ELM2, the sacrificial layer AOM2, and the sacrificial layer MWM2 are formed to cover the substrate BA1, the sacrificial layer AOY1, the sacrificial layer MWY1, and the anode AD2 (see FIG. 12). The organic EL layer ELM2 is the organic EL layer corresponding to the pixel PX2.

[0068] A resist mask RES2 is formed on the sacrificial layer MWM2 facing the anode AD2. Using the resist mask RES2, the sacrificial layer MWM2 is partially removed by etching. As a result, the sacrificial layer MWY2 is formed in an island shape with the sacrificial layer AOM2 interposed therebetween and facing the anode AD2 (see FIG. 13).

[0069] Next, the resist mask RES2 on the sacrificial layer MWY2 is removed (see FIG. 14). Using the sacrificial layer MWY2 formed in an island shape as a mask, the sacrificial layer AOM2 and the organic EL layer ELM2 are partially removed by etching. As a result, the organic EL layer ELY2 and the upper layer AOU2 of the sacrificial layer are formed in an island shape between the cathode CD2 and the sacrificial layer MWY2 (see FIG. 15).

[0070] A sidewall AOS2 is formed in contact with the sides of the anode AD2, the organic EL layer ELY2, the upper layer AOU2, and the sacrificial layer MWY2. The sidewall AOS2 is formed of the same material as the sacrificial layer AOM2. The upper layer AOU2 and the sidewall AOS2 are combined to form a sacrificial layer AOY2 (see FIG. 16).

[0071] The sacrificial layer MWY1 and the sacrificial layer MWY2 are removed (see FIG. 17). At this time, the upper layer AOU1 of the sacrificial layer AOY1 and the upper layer AOU2 of the sacrificial layer AOY2 are planarized.

[0072] Covering the upper layer AOU1 of the sacrificial layer AOY1 and the sidewall AOS1, and the upper layer AOU2 of the sacrificial layer AOY2 and the sidewall AOS2, a sacrificial layer is formed of the same material as these sacrificial layers, that is, the same material as the sacrificial layer AOM1 and the sacrificial layer AOM2. As a result, the upper layer AOU1, the sidewall AOS1, the upper layer AOU2, the sidewall AOS2, and the newly formed sacrificial layer are integrated to form a sacrificial layer AOT (see FIG. 18).

[0073] The thickness tu1 of the upper layer AOU1 and the thickness tu2 of the upper layer AOU2 are approximately the same as the thickness ts1 of the sidewall AOS1 and the thickness ts2 of the sidewall AOS2. Of the sacrificial layer AOT, the region in contact with the substrate BA1 is defined as a region AOB. The thickness tb of the region AOB is thinner than the thickness ts1, the thickness ts2, the thickness tu1, and the thickness tu2.

[0074] A bank BK is formed between the organic EL layer ELY1 and the organic EL layer ELY2 in contact with the sacrificial layer AOT. Above each of the organic EL layer ELY1 and the organic EL layer ELY2, no bank BK is formed. That is, an opening OP1 and an opening OP2 are provided above the organic EL layer ELY1 and the organic EL layer ELY2, respectively (see FIG. 19).

[0075] The sacrificial layer AOT in the opening OP1 and the opening OP2 is removed. As a result, the organic EL layer ELY1 and the organic EL layer ELY2 are exposed within the opening OP1 and the opening OP2 provided in the bank BK and the sacrificial layer AOT (see FIG. 20).

[0076] A cathode CD, an insulating layer INS, and an insulating layer PCL are formed to cover the exposed organic EL layer ELY1, the organic EL layer ELY2, and the bank BK. A substrate BA2 is provided on the insulating layer PCL.

[0077] In the opening OP1 and the opening OP2, a cathode CD is provided on the organic EL layer ELY1 and the organic EL layer ELY2, respectively. Thus, the display device DSP of Embodiment 1 is formed (see FIG. 21).

[0078] The insulating layer INS is formed of, for example, silicon nitride (SiN). The insulating layer INS prevents moisture from entering the organic EL layer from the outside. The insulating layer PCL is formed of, for example, a resin insulating material. The insulating layer PCL has a function of planarizing the surface. The substrate BA2 may use the same material as the substrate BA1.

[0079] To form the anode and the organic EL layer of the pixel PX3 which is the third pixel, after the process shown in FIG. 16 is completed, in the same manner as FIG. 12, an organic EL layer and a sacrificial layer may be formed to cover the anode of the pixel PX3. In the same manner as FIG. 16, after the side wall of the sacrificial layer of the pixel PX3 is formed, the process shown in FIG. 17 may be advanced.

[0080] In this embodiment, the pixel PX1, the pixel PX2, and the pixel PX3 may be the pixel PXR, the pixel PXG, and the pixel PXB, respectively. As a result, the thickness of the transparent electrode TD decreases in the order of the pixel PXR, the pixel PXG, and the pixel PXB.

[0081] The sacrificial layer AOT (sacrificial layer AOY1, sacrificial layer AOY2, sidewalls AOS1, sidewalls AOS2, and region AOB) corresponds to the protective layer AOL shown in FIG. 4. By covering the side surfaces of the organic EL layer with the protective layer AOL (sacrificial layer AOT) formed of aluminum oxide, the organic EL layer can be protected.

[0082] FIGS. 22 to 24 are cross-sectional views showing a method for manufacturing a display device of a comparative example. To manufacture the display device DSPr of the comparative example, first, an anode AD1 and an anode AD2 are formed on a substrate BA1 (see FIG. 22). Assume that the anode AD1 and the anode AD2 in the comparative example are transparent electrodes formed of a metal oxide. Examples of such a metal oxide include the above-mentioned indium tin oxide and indium zinc oxide. The process shown in FIG. 22 corresponds to the process shown in FIG. 6.

[0083] Through the processes shown in FIGS. 7 to 9, an organic EL layer ELY1, an upper layer AOU1 of the sacrificial layer, and a sacrificial layer MWY1 are formed on the anode AD1. The sacrificial layer is removed on the anode AD2 (see FIG. 23). The process shown in FIG. 23 corresponds to the process shown in FIG. 10.

[0084] Next, in the same manner as in FIG. 11, sidewalls AOS1 are formed in contact with the side surfaces of the anode AD1, the organic EL layer ELY1, the upper layer AOU1, and the sacrificial layer MWY1. Similar to the above, a material film that becomes the sidewalls AOS1 is formed to cover the laminate of the organic EL layer ELY1, the upper layer AOU1, and the sacrificial layer MWY1. Then, the material film is anisotropically etched to leave only the region in contact with the side surface of the laminate and remove other regions, thereby forming the sidewalls AOS1.

[0085] The material of the sidewall AOS1 is the same as that of the sacrificial layer AOM1, for example, aluminum oxide (AlOx). On the other hand, the anodes AD1 and AD2 are formed of, for example, a metal oxide as described above.

[0086] That is, the sidewall AOS1, and the anodes AD1 and AD2 are formed of a material containing a metal oxide. When etching such a metal oxide, it may be necessary to use an etching gas with no selectivity.

[0087] In this case, in the etching for forming the sidewall AOS1, the anode AD2 may be removed together (see FIG. 24). If the anode is removed, the desired characteristics cannot be obtained for that pixel due to a high voltage. In such a display device, the display quality deteriorates.

[0088] In the display device DSP of this embodiment, the anode AD is formed of a reflective electrode RD and a transparent electrode TD. The transparent electrode TD is formed to have a thickness that does not disappear even if etched in the initial film formation process. In this embodiment, the thicknesses t10 and t20 shown in FIG. 6 are made sufficient thicknesses. That is, the thicknesses t10 and t20 are sufficient thicknesses such that the transparent electrode TD does not disappear due to etching in later processes. The thickness of the transparent electrode TD becomes thinner in the order of the pixel PXR that emits red light, the pixel PXG that emits green light, and the pixel PXB that emits blue light.

[0089] The display device DSP of this embodiment can be manufactured without disappearing the anode in the manufacturing process shown in FIGS. 6 to 21. Therefore, it is possible to prevent the occurrence of non-emission of pixels and the deterioration of the display quality of the display device DSP.

[0090] [Embodiment 2] FIG. 25 is a cross-sectional view showing a configuration example of the display device in Embodiment 2. In the configuration example shown in FIG. 25, compared with the configuration example shown in FIG. 4, the thickness of the transparent electrode TDG of the pixel PXG that emits green light is different in that it is thicker than the thickness of the transparent electrode TDR of the pixel PXR that emits red light.

[0091] In FIG. 25, the thickness tg of the transparent electrode TDG is thicker than the thickness tr of the transparent electrode TDR. The thickness tr of the transparent electrode TDR is thicker than the thickness tb of the transparent electrode TDB (tg > tr > tb). The thicknesses of the reflective electrodes RDR, RDG, and RDB are the same as in FIG. 4.

[0092] The green light emitted from the organic EL layer ELYG of the pixel PXG has a higher luminance compared to the red light and the blue light. Therefore, even if light is absorbed by the transparent electrode TDG and the light amount decreases, the luminance of the pixel PXG does not extremely decrease compared to the luminance of the pixel PXR and the luminance of the pixel PXB.

[0093] To obtain the display device DSP shown in FIG. 25, it may be manufactured by the manufacturing processes shown in FIGS. 6 to 21 in the same manner as in Embodiment 1. In this case, the pixel PX1 and the pixel PX2 are made the pixel PXG and the pixel PXR, respectively. The transparent electrodes TD1 and TD2 correspond to the transparent electrodes TDG and TDR, respectively. In the manufacturing process shown in FIG. 6, the thickness t10 of the transparent electrode TD1 (transparent electrode TDG) is made thicker than the thickness t20 of the transparent electrode TD2 (transparent electrode TDR) (t10 > t20).

[0094] Also in the process shown in FIG. 11, the thickness t11 of the transparent electrode TD1 (transparent electrode TDG) becomes thicker than the thickness t21 of the transparent electrode TD2 (transparent electrode TDR) (t11 > t21).

[0095] The pixel PXB corresponds to the pixel PX3 described in Embodiment 1. Let the transparent electrode of the pixel PX3 be the transparent electrode TD3. Let the initial thickness of the transparent electrode TD3, that is, the thickness of the transparent electrode TD3 formed in the process shown in FIG. 6 be the thickness t30. Also, let the thickness of the transparent electrode TD3 after anisotropic etching, that is, the thickness of the transparent electrode TD3 in the process corresponding to FIG. 11 be the thickness t31.

[0096] The thickness t30 is thinner than the thicknesses t10 and t20. That is, t10 > t20 > t30 holds. Also, the thickness t31 is thinner than the thicknesses t11 and t20. That is, t11 > t21 > t31 holds. Namely, the thickness of the transparent electrode TD3 of the pixel PX3, that is, the transparent electrode TDB of the pixel PXB, is thinner than the thicknesses of the transparent electrodes of the pixels PXR and PXG, whether in the initial state or after anisotropic etching.

[0097] As described above, also in Embodiment 2, it is possible to manufacture the display device DSP without disappearing the transparent electrode of the anode. It is possible to prevent the pixels from not emitting light and to prevent the display quality of the display device DSP from deteriorating.

[0098] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and its equivalent scope.

Description of Reference Numerals

[0099] AD... Anode, AOL... Protection layer, AOS1... Side wall, AOS2... Side wall, AOU1... Upper layer, AOU2... Upper layer, AOY1... Sacrificial layer, AOY2... Sacrificial layer, DSP... Display device, ELY... Organic EL layer, PX... Pixel, RD... Reflective electrode, TD... Transparent electrode, TD1... Transparent electrode, TD2... Transparent electrode, TD3... Transparent electrode, TDB... Transparent electrode, TDG... Transparent electrode, TDR... Transparent electrode.

Claims

1. A plurality of pixels including a first pixel that emits red light, a second pixel that emits green light, and a third pixel that emits blue light; A bank provided between adjacent ones of the pixels; Comprising; Each of the plurality of pixels On a substrate, An anode including a reflective electrode and a transparent electrode; An organic EL layer provided on the anode; A protective layer provided to cover a side surface of the organic EL layer; A cathode provided at an opening of the protective layer and the bank and in contact with the organic EL layer; Comprising; The first anode of the first pixel includes a first reflective electrode and a first transparent electrode; The second anode of the second pixel includes a second reflective electrode and a second transparent electrode; The third anode of the third pixel includes a third reflective electrode and a third transparent electrode; A display device, wherein a first thickness of the first transparent electrode, a second thickness of the second transparent electrode, and a third thickness of the third transparent electrode are thin in this order.

2. The display device according to claim 1, wherein the first transparent electrode and the second transparent electrode contain indium tin oxide or indium zinc oxide.

3. The display device according to claim 1, wherein the protective layer is formed of aluminum oxide.

4. The display device according to claim 1, wherein the reflective electrode contains silver or a molybdenum tungsten alloy.

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