Light-emitting element, display device, and method for forming functional layer

Abstract

A red-light-emitting element (5R) includes a first electrode (22), a second electrode (25), a quantum dot (QD1) that is a first functional material, and a first medium material (MR1). The red-light-emitting element (5R) is provided with a red-light-emitting layer (24REM) that is a first functional layer formed between the first electrode (22) and the second electrode (25) so as to be larger in plan view than the smaller of the first electrode (22) and the second electrode (25). The red-light-emitting layer (24REM) includes a first portion (24REM1) formed in a light-emitting region (HR), and a second portion (24REM2) formed in a non-light-emitting region (NHR). The second portion (24REM2) includes a second region (HD) having a second area greater than a first area, where the first area is the total area of the first medium material (MR1) in a first region (LD) of a prescribed size included in the first portion (24REM1) in a given cross-section taken along the thickness direction of the red-light-emitting layer (24REM), and the second area is the total area of the first medium material (MR1) in the second region (HD), which is of the prescribed size and is included in the second portion (24REM2) in the aforementioned given cross-section.

Description

Light-emitting element, display device, and method for forming functional layer

[0001] The present disclosure relates to a light-emitting element, a display device, and a method for forming a functional layer.

[0002] In recent years, various display devices equipped with light-emitting elements have been developed, and in particular, display devices equipped with OLEDs (Organic Light Emitting Diodes) or QLEDs (Quantum dot Light Emitting Diodes) have attracted much attention because of their ability to achieve low power consumption, thinness, high image quality, and the like.

[0003] For example, Patent Documents 1 and 2 disclose that an organic material ink is applied by a wet application method or the like to form a light-emitting element having a functional layer of a predetermined shape.

[0004] Japanese Patent Publication No. 2011-60435 Japanese Patent Publication No. 2011-60518

[0005] The functional layers of the predetermined shape described in Patent Documents 1 and 2 have substantially the same overall configuration, and therefore have a problem in that the specific function of the functional layer is relatively easily exhibited even in the functional layer provided in a non-light-emitting region where the specific function of the functional layer does not need to be exhibited. For example, when the functional layer is a charge transport layer, there is a problem in that the charge transport function is relatively easily exhibited even in the charge transport layer provided in a non-light-emitting region where the charge transport function does not need to be exhibited.

[0006] One aspect of the present disclosure aims to provide a light-emitting element, a display device, and a method for forming a functional layer that can suppress the expression of a specific function possessed by a first functional material in a second portion that is a part of the first functional layer.

[0007] In order to solve the above-mentioned problems, the light-emitting element of the present disclosure comprises a first electrode, a second electrode, a first functional material, and a first medium material, and a first functional layer formed between the first electrode and the second electrode and larger in a planar view than the smaller of the first electrode and the second electrode, wherein the first functional layer includes a first portion formed in a light-emitting region and a second portion formed in a non-light-emitting region, wherein the first area is the sum of the areas of the first medium material in first regions of a predetermined size included in the first portion in a cross section cut along the thickness direction of the first functional layer, and the second area is the sum of the areas of the first medium material in second regions of a predetermined size included in the second portion in the cross section, and the second portion includes the second region having the second area larger than the first area.

[0008] In order to solve the above-mentioned problems, the light-emitting element of the present disclosure comprises a first electrode, a second electrode, a first functional material, and a first medium material, and a first functional layer formed between the first electrode and the second electrode and larger in a planar view than the smaller of the first electrode and the second electrode, wherein the first functional layer includes a first portion formed in a light-emitting region and a second portion formed in a non-light-emitting region, wherein the concentration of the first medium material in a first unit portion having a predetermined volume included in the first portion is defined as a first concentration, and the concentration of the first medium material in a second unit portion having the predetermined volume included in the second portion is defined as a second concentration, and the second portion includes the second unit portion having the second concentration higher than the first concentration.

[0009] In order to solve the above-mentioned problems, the display device of the present disclosure includes a plurality of the light-emitting elements.

[0010] In order to solve the above-mentioned problems, the method for forming a functional layer disclosed herein includes a first step of forming a first functional layer using a mixed solution containing a first functional material and a first medium material, and a second step of making the amount of the first medium material contained in a first portion of the first functional layer less than the amount of the first medium material contained in a second portion of the first functional layer.

[0011] According to one aspect of the present disclosure, a light-emitting element, a display device, and a method for forming a functional layer can be provided, which can suppress the expression of a specific function possessed by the first functional material in a second portion, which is a part of the first functional layer.

[0012] 7 is a plan view showing a schematic configuration of a display device of embodiment 1. FIG. 1 is a cross-sectional view showing a schematic configuration of a display region of the display device of embodiment 1. FIG. 1 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display device of embodiment 1. FIG. 2 is a diagram showing a schematic distribution state of quantum dots, which are a first functional material, and a first medium material, in a cross-section of a red light-emitting layer provided in the red light-emitting element shown in FIG. 3. FIG. 3 is a diagram showing a part of a process for forming a red light-emitting layer provided in the red light-emitting element shown in FIG. 3. FIG. 4 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in a display device of embodiment 2. FIG. 5 is a diagram showing an example of a process for forming a red light-emitting layer provided in the red light-emitting element shown in FIG. 7. FIG. 6 is a diagram showing another example of a process for forming a red light-emitting layer provided in the red light-emitting element shown in FIG. 7. FIG. 7 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in a display device of embodiment 3. FIG. 8 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in a display device of embodiment 4. FIG. 9 is a diagram showing an example of a process for forming a red light-emitting layer provided in the red light-emitting element shown in FIG. 11. FIG. 11 is a diagram showing an example of a process for forming a red light-emitting layer of a red light-emitting element provided in a display device of embodiment 5. FIG. 12 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display device of embodiment 6. FIG. 13 is a cross-sectional view showing a schematic configuration of a red light-emitting element and a green light-emitting element provided in the display device of embodiment 7. FIG. 14 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display device of embodiment 8. FIG. 15 is a plan view showing a schematic configuration of a display device of embodiment 9. FIG. 16 is a cross-sectional view showing a schematic configuration of a display area of ​​the display device of embodiment 9. FIG. 17 is a diagram showing an example of a manufacturing process of the display device of embodiment 10. FIG. 18 is a cross-sectional view showing a schematic configuration of the display area of ​​the display device of embodiment 10. FIG. 19 is a cross-sectional view showing a schematic configuration of the display area of ​​the display device of embodiment 11. FIG. 20 is a cross-sectional view showing a schematic configuration of the display area of ​​the display device of embodiment 12. FIG. 21 is a cross-sectional view showing a schematic configuration of the display area of ​​the display device of embodiment 13.

[0013] The following describes embodiments of the present disclosure with reference to Figures 1 to 23. For the sake of convenience, components having the same functions as those described in specific embodiments will be denoted by the same reference numerals, and descriptions thereof may be omitted.

[0014] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0015] As shown in Fig. 1, the display device 1 includes a frame area NDA and a display area DA. The display area DA of the display device 1 includes a plurality of pixels PIX, each of which includes a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP. In this embodiment, a case in which one pixel PIX is configured with a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP will be described as an example, but this is not limiting. For example, one pixel PIX may include subpixels of other colors in addition to the red subpixel RSP, the green subpixel GSP, and the blue subpixel BSP.

[0016] FIG. 2 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1 of the first embodiment.

[0017] As shown in Figure 2, in the display area DA of the display device 1, a barrier layer 3, a thin film transistor layer 4 including a transistor TR, a red light-emitting element 5R, a green light-emitting element 5G, a blue light-emitting element 5B and a bank 23, a sealing layer 6, and a functional film 39 are provided on a substrate 12 in this order from the substrate 12 side.

[0018] The red subpixel RSP provided in the display area DA of the display device 1 includes a red light-emitting element 5R (light-emitting element), the green subpixel GSP provided in the display area DA of the display device 1 includes a green light-emitting element 5G (light-emitting element), and the blue subpixel BSP provided in the display area DA of the display device 1 includes a blue light-emitting element 5B (light-emitting element). The red light-emitting element 5R included in the red subpixel RSP includes a first electrode 22, a functional layer 24R including a red light-emitting layer, and a second electrode 25. The green light-emitting element 5G included in the green subpixel GSP includes a first electrode 22, a functional layer 24G including a green light-emitting layer, and a second electrode 25. The blue light-emitting element 5B included in the blue subpixel BSP includes a first electrode 22, a functional layer 24B including a blue light-emitting layer, and a second electrode 25. 2, in order to show a schematic configuration of the display area DA of the display device 1, the functional layer 24R including a red light-emitting layer, the functional layer 24G including a green light-emitting layer, and the functional layer 24B including a blue light-emitting layer are schematically illustrated as being provided for each subpixel of each color. In FIG. 2, the hole transport layer 24H and the electron transport layer 24E of the functional layer 24R are not illustrated as being provided as a common layer (single layer) for the red subpixel RSP, the green subpixel GSP, and the blue subpixel BSP, respectively. However, in reality, like the functional layer 24R including the red light-emitting layer 24REM provided in the red light-emitting element 5R shown in FIG. 3, the hole transport layer 24H and the electron transport layer 24E, excluding the red light-emitting layer 24REM, are each formed over the entire surface of the display area DA and are provided as a common layer for the subpixels of each color, similar to the second electrode 25.

[0019] The substrate 12 may be, for example, a resin substrate made of a resin material such as polyimide, or a glass substrate. In this embodiment, since the display device 1 is a flexible display device, a case where a resin substrate made of a resin material such as polyimide is used as the substrate 12 will be described as an example, but this is not limiting. If the display device 1 is a non-flexible display device, a glass substrate can be used as the substrate 12.

[0020] The barrier layer 3 is a layer that prevents foreign substances such as water and oxygen from penetrating into the transistor TR, the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B, and can be composed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these, formed by the CVD method.

[0021] The transistor TR portion of the thin film transistor layer 4 including the transistor TR includes the semiconductor film SEM and doped semiconductor films SEM′ and SEM″, an inorganic insulating film 16, a gate electrode G, an inorganic insulating film 18, an inorganic insulating film 20, a source electrode S and a drain electrode D, and a planarization film 21, and the portion of the thin film transistor layer 4 including the transistor TR other than the transistor TR portion includes the inorganic insulating film 16, the inorganic insulating film 18, the inorganic insulating film 20, and the planarization film 21.

[0022] The semiconductor films SEM, SEM', and SEM'' may be made of, for example, low-temperature polysilicon (LTPS) or an oxide semiconductor (for example, an In-Ga-Zn-O based semiconductor). In this embodiment, the case where the transistor TR has a top-gate structure will be described as an example, but the present invention is not limited to this, and the transistor TR may also have a bottom-gate structure.

[0023] The gate electrode G and the source electrode S and drain electrode D can be formed of a single layer or a multilayer film of a metal containing at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper, for example.

[0024] The inorganic insulating films 16, 18 and 20 can be formed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these films, which are formed by the CVD method.

[0025] The planarizing film 21 can be made of a coatable organic material such as polyimide or acrylic.

[0026] The red light-emitting element 5R includes a first electrode 22 above the planarization film 21, a functional layer 24R including a red light-emitting layer, and a second electrode 25. The green light-emitting element 5G includes a first electrode 22 above the planarization film 21, a functional layer 24G including a green light-emitting layer, and a second electrode 25. The blue light-emitting element 5B includes a first electrode 22 above the planarization film 21, a functional layer 24B including a blue light-emitting layer, and a second electrode 25. The insulating bank 23 covering the edge of the first electrode 22 can be formed by applying an organic material such as polyimide or acrylic and then patterning it by photolithography. In this embodiment, the case where the bank 23 is provided will be described as an example, but the bank 23 may not be provided.

[0027] The sealing layer 6 is a light-transmitting film, and can be composed of, for example, an inorganic sealing film 26 that covers the second electrode 25, an organic film 27 that is above the inorganic sealing film 26, and an inorganic sealing film 28 that is above the organic film 27. The sealing layer 6 prevents foreign substances such as water and oxygen from penetrating into the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B.

[0028] The inorganic sealing films 26 and 28 are each an inorganic film, and may be formed, for example, by a CVD method using a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film thereof. The organic film 27 is a light-transmitting organic film with a planarizing effect, and may be formed, for example, using a coatable organic material such as acrylic. The organic film 27 may also be formed, for example, by an inkjet method. In this embodiment, the sealing layer 6 is formed of two inorganic films and one organic film disposed between the two inorganic films. However, the stacking order of the two inorganic films and one organic film is not limited to this. Furthermore, the sealing layer 6 may be formed solely of an inorganic film, solely of an organic film, one inorganic film and two organic films, or two or more inorganic films and two or more organic films.

[0029] The functional film 39 is a film having at least one of an optical compensation function, a touch sensor function, and a protection function, for example.

[0030] FIG. 3 is a cross-sectional view showing a schematic configuration of the red light emitting element 5R provided in the display device 1 of the first embodiment.

[0031] FIG. 4 is a diagram showing a schematic distribution state of quantum dots QD1, which are the first functional material, and a first medium material MR1 in a cross section of the red light-emitting layer 24REM provided in the red light-emitting element 5R shown in FIG.

[0032] 3 , the red light-emitting element 5R includes a first electrode 22, a second electrode 25, and a functional layer 24R including a red light-emitting layer 24REM. In this embodiment, the first electrode 22 is an anode, the second electrode 25 is a cathode, and the functional layer 24R including the red light-emitting layer 24REM is a laminated film in which a hole transport layer 24H, a red light-emitting layer 24REM, and an electron transport layer 24E are stacked in this order from the first electrode 22 side. However, the present invention is not limited to this. As long as the functional layer 24R including the red light-emitting layer 24REM includes the red light-emitting layer 24REM, it may be composed of only the red light-emitting layer 24REM, or it may be composed of the red light-emitting layer 24REM and one or more layers selected from a hole injection layer, a hole transport layer 24H, an electron transport layer 24E, and an electron injection layer.

[0033] The first functional layer, which is one of the functional layers 24R including the red light-emitting layer 24REM, includes a first functional material and a first medium material, and is formed between the first electrode 22 and the second electrode 25 so as to be larger in plan view than the smaller of the first electrode 22 and the second electrode 25. The first functional layer includes a first portion that is the first functional layer formed in the light-emitting region HR, and a second portion that is the first functional layer formed in the non-light-emitting region NHR. In this embodiment, an example will be described in which the first functional layer is the red light-emitting layer 24REM that includes quantum dots QD1 and a first medium material MR1 as the first functional material. However, as will be described later, the first functional layer may be a layer other than the red light-emitting layer 24REM in the functional layer 24R including the red light-emitting layer 24REM, and may be, for example, any one of a hole injection layer, a hole transport layer 24H, an electron transport layer 24E, and an electron injection layer. In the green light-emitting element 5G, any one of the functional layers 24G including the green light-emitting layer is the first functional layer, and in the blue light-emitting element 5B, any one of the functional layers 24B including the blue light-emitting layer is the first functional layer.

[0034] 3 and 4 , the first area is the sum of the areas of the first medium material MR1 in first regions LD of a predetermined size included in a first portion 24REM1 in a cross section taken along the thickness direction of the red light-emitting layer 24REM, which is the first functional layer. The second area is the sum of the areas of the first medium material MR1 in second regions HD of a predetermined size included in a second portion 24REM2 in the cross section. The second portion 24REM2 includes a second region HD having the second area larger than the first area. The first region LD and the second region HD have the same size. The first region LD and the second region HD may each have the same size, for example, 1% or more of the size of the cross section of the red light-emitting layer 24REM, which is the first functional layer, and may be smaller than the size of the first portion 24REM1 or the size of the second portion 24REM2 in the cross section of the red light-emitting layer 24REM, which is the first functional layer. For example, the first region LD and the second region HD, which are the same size, may each have the smaller of the size of the first portion 24REM1 and the size of the second portion 24REM2 in the cross section. Furthermore, when the first region LD and the second region HD are included in the first portion 24REM1 and the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, respectively, and have the same film thickness, the first region LD and the second region HD may each be defined by a region between the bottom surface and the top surface, so as to include the top surface that is in contact with the electron transport layer 24E of the red light-emitting layer 24REM, which is the first functional layer, and the bottom surface that is in contact with the hole transport layer 24H of the red light-emitting layer 24REM, which is the first functional layer. On the other hand, when the first region LD and the second region HD are included in the first portion 24REM1 and the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, respectively, and have different film thicknesses, the first region LD and the second region HD may be defined as a region between the bottom surface and the top surface, including the bottom surface and the top surface, so as to have the same size. Furthermore, the first region LD may be defined to include the center of the light-emitting region HR, and the second region HD may be defined to include an edge portion of the red light-emitting layer 24REM, which is the first functional layer.

[0035] As shown in FIG. 3 , in this embodiment, a hole transport layer 24H, for example, provided as a common layer for the sub-pixels of each color is provided between the first electrode 22, which is an anode, and the red light-emitting layer 24REM, which is a first functional layer, and is formed to be equal to or larger than the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, in a planar view. Also, an electron transport layer 24E, for example, provided as a common layer for the sub-pixels of each color is provided between the second electrode 25, which is a cathode, and the red light-emitting layer 24REM, which is the first functional layer, and is formed to be equal to or larger than the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, in a planar view. This example illustrates a red light-emitting element 5R, but is not limited to this. For example, the red light emitting element may be one in which the first electrode 22 is a cathode, the second electrode 25 is an anode, and between the first electrode 22 and the red light emitting layer 24REM which is the first functional layer, there is provided, for example, an electron transport layer 24E provided as a common layer for the sub-pixels of each color, as a second functional layer formed to be equal to or larger than the size of the first portion 24REM1 of the red light emitting layer 24REM which is the first functional layer in a planar view, and between the second electrode 25 and the red light emitting layer 24REM which is the first functional layer, there is provided, for example, a hole transport layer 24H provided as a common layer for the sub-pixels of each color, as another second functional layer formed to be equal to or larger than the size of the first portion 24REM1 of the red light emitting layer 24REM which is the first functional layer in a planar view.

[0036] As shown in FIGS. 3 and 4 , the concentration of the first medium material MR1 in a first unit having a predetermined volume included in the first portion 24REM1 is defined as a first concentration, and the concentration of the first medium material MR1 in a second unit having the predetermined volume included in the second portion 24REM2 is defined as a second concentration. The second portion 24REM2 includes the second unit having the second concentration higher than the first concentration. The volumes of the first unit and the second unit are the same. The predetermined volume may be, for example, 1% or more of the volume of the first functional layer and less than the smaller of the volume of the first portion 24REM1 of the red light-emitting layer 24REM and the volume of the second portion 24REM2 of the red light-emitting layer 24REM, which are the first functional layer. For example, each of the first unit and the second unit may have the smaller volume of the volume of the first portion 24REM1 and the volume of the second portion 24REM2. Furthermore, when the first unit and the second unit are included in the first portion 24REM1 and the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, respectively, and have the same film thickness, each of the first unit and the second unit may be defined by a portion between the bottom surface and the top surface, including a top surface that contacts the electron transport layer 24E of the red light-emitting layer 24REM, which is the first functional layer, and a bottom surface that contacts the hole transport layer 24H of the red light-emitting layer 24REM, which is the first functional layer. On the other hand, when the first unit and the second unit are included in the first portion 24REM1 and the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, respectively, and have different film thicknesses, each of the first unit and the second unit may be defined by a portion between the bottom surface and the top surface, including the bottom surface and the top surface, so as to have the same volume. Furthermore, the first unit may be defined to include the center of the light-emitting region HR, and the second unit may be defined to include an end portion of the red light-emitting layer 24REM, which is the first functional layer. The concentration of the first medium material MR1 in the predetermined volume can be confirmed by measuring the concentration ratio distribution in the depth direction of the red light-emitting layer 24REM, which is the first functional layer, using, for example, TOF-SIMS.

[0037] As described above, in the red light-emitting element 5R including the red light-emitting layer 24REM as the first functional layer described above, and the display device 1 including the red light-emitting element 5R, the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second region HD of a predetermined size in the second portion 24REM2 formed in the non-light-emitting region NHR is larger than the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first region LD of a predetermined size in the first portion 24REM1 formed in the light-emitting region HR. Alternatively, the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second unit having a predetermined volume in the second portion 24REM2 formed in the non-light-emitting region NHR is higher than the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first unit having the predetermined volume in the first portion 24REM1 formed in the light-emitting region HR. Therefore, leakage current can be suppressed in the red light-emitting layer 24REM, which is the first functional layer formed in the non-light-emitting region NHR. That is, the expression of a specific function possessed by the first functional material can be suppressed in the second portion 24REM2, which is a part of the red light-emitting layer 24REM, which is the first functional layer. In this embodiment, the red light-emitting element 5R has been described as an example. However, by providing a green light-emitting layer or a blue light-emitting layer including a first portion and a second portion, similar to the red light-emitting layer 24REM, which is the first functional layer, the green light-emitting element 5G and the blue light-emitting element 5B can also achieve the same effect as the red light-emitting element 5R.

[0038] 4 , in the red light-emitting layer 24REM serving as the first functional layer, the average distance between the quantum dots QD1, which are particles, in the first region LD of a predetermined size in the first portion 24REM1 formed in the light-emitting region HR is shorter than the average distance between the quantum dots QD1, which are particles, in the second region HD of a predetermined size in the second portion 24REM2 formed in the non-light-emitting region NHR. Therefore, in the red light-emitting layer 24REM serving as the first functional layer, the average distance between the quantum dots QD1, which are particles, in the first portion 24REM1 including the first region LD as described above is shorter than the average distance between the quantum dots QD1, which are particles, in the second portion 24REM2 including the second region HD as described above.

[0039] 3 and 4, the red light-emitting layer 24REM, which is the first functional layer, includes a protrusion at an end 24REME of the second portion 24REM2 of the red light-emitting layer 24REM, which is thicker than the other portions of the red light-emitting layer 24REM. The protrusion of the red light-emitting layer 24REM, which is the first functional layer, has a high resistance due to its thicker film thickness, and therefore can further suppress leakage current from flowing in the second portion 24REM2.

[0040] In this embodiment, the first functional material contained in the red light-emitting layer 24REM, which is the first functional layer, is a plurality of particles, such as quantum dots QD1, each of which is a nanoparticle. However, this is not limiting. The quantum dots QD1 may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with a continuously varying core / shell ratio. Note that the shell may partially cover the core, but it is preferable for the shell to completely cover the core. The core material of the quantum dot QD1 may be, for example, a II-VI group semiconductor crystal such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, PbS, PbSe, HgS, HgSe, or HgTe, a III-V group semiconductor crystal such as GaAs, GaP, InN, InAs, InP, or InSb, or Ga ３ S ２ , Ga ２ Se ３ , In ２ S ３ , In ２ Se ３ Crystals of III-VI group semiconductors such as CuInGaS, AgInGaS, CuInGaS, AgInGaZnS, CuInGaSe, AgInGaSe, etc., crystals of I-III-VI group semiconductors such as C and Si, crystals of IV group semiconductors such as CsPbI ３ , CsPbBr ３ , CsPbCl ３The shell material may be made of a semiconductor crystal having a perovskite structure such as ZnS. The shell material is preferably selected from the same material group as the core material, has a lattice constant close to that of the core material, and has a larger band gap than the core material. In this embodiment, the quantum dot QD1, which is the first functional material, has a core / shell structure, and the core material is made of InP and the shell material is made of a metal sulfide (e.g., zinc sulfide (ZnS)). However, the present invention is not limited to this.

[0041] In this embodiment, the first medium material MR1 included in the red-light-emitting layer 24REM, which is the first functional layer, is described as being composed of a ligand. However, this is not limiting, and the first medium material MR1 may include at least one of a ligand, a dispersant, and a matrix. Here, the term "ligand" refers to a molecule containing a group capable of coordinating with the first functional material, the term "dispersant" refers to a molecule not containing a group capable of coordinating with the first functional material, and the term "matrix" refers to a combination of multiple ligands or dispersants containing functional groups that can be bonded by energy application (e.g., baking or exposure). The first medium material MR1 may further include at least one of a halogen element and a halogen compound. The term "first medium material MR1" refers to all substances in the first functional layer other than the first functional material. The first medium material MR1 may exist alone in the first functional layer or may be bonded to the first functional material.

[0042] In this embodiment, octanethiol is used as the ligand constituting the first medium material MR1, but the present invention is not limited to this. Octanethiol exhibits surface activity and is therefore soluble in both polar and low-polarity solvents. Furthermore, octanethiol has a thiol group, so it can be coordinated to the shell (e.g., zinc sulfide (ZnS)) of the quantum dots QD1, which are the first functional material. The quantum dots QD1, which are the first functional material with octanethiol coordinated to the surface, do not disperse in polar solvents because the low-polarity alkyl chains of octanethiol are coordinated toward the surface.

[0043] In this embodiment, InP is used as the core of the quantum dot QD1, which is the first functional material, and octanethiol is used as the ligand that constitutes the first medium material MR1, so the electrical conductivity of the first medium material MR1 is lower than the electrical conductivity of the core of the quantum dot QD1.

[0044] Furthermore, in this embodiment, a metal sulfide (e.g., zinc sulfide (ZnS)) is used as the shell of the quantum dot QD1, which is the first functional material, and octanethiol is used as the ligand that constitutes the first medium material MR1, so the electrical conductivity of the first medium material MR1 is lower than the electrical conductivity of the core of the quantum dot QD1.

[0045] 3 and 4 , the red light-emitting element 5R includes a bank 23 that includes a portion that is formed thicker than the first electrode 22, and the hole transport layer 24H, which is a second functional layer formed on the bank 23 and is provided as a common layer for the sub-pixels of each color, tends to have a thickness that is thinner than the hole transport layer 24H formed other than on the bank 23. As shown in Fig. 3 , the region LP formed on the bank 23 with a thickness thinner than the portion other than on the bank 23 can become a leakage path for current. Therefore, in a light-emitting element including such a region LP, if leakage current flows through the region LP, the light-emitting efficiency of the light-emitting element will be reduced, resulting in a problem that satisfactory light-emitting characteristics cannot be obtained.

[0046] Therefore, in the red light-emitting element 5R, as described above, the electrical conductivity of the first medium material MR1 is lower than the electrical conductivity of the quantum dots QD1. Furthermore, in a cross section cut along the thickness direction of the red light-emitting layer 24REM, which is the first functional layer, the total area of ​​the first medium material MR1 included in the second region HD of a predetermined size in the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, is greater than the total area of ​​the first medium material MR1 included in the first region LD of the predetermined size in the first portion 24REM1. Alternatively, the concentration of the first medium material MR1 included in the second unit portion of a predetermined volume in the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, is higher than the concentration of the first medium material MR1 included in the first unit portion of a predetermined volume in the first portion 24REM1. Therefore, the electrical conductivity of the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, is higher than the electrical conductivity of the second portion 24REM2 of the red light-emitting layer 24REM. In other words, the electrical conductivity of the second portion 24REM2 of the red light-emitting layer 24REM is lower than the electrical conductivity of the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, and therefore the second portion 24REM2 of the red light-emitting layer 24REM can prevent leakage current from flowing through the above-mentioned region LP.

[0047] 3 and 4, in the red light-emitting element 5R, the film thickness of the end portion 24REME of the red light-emitting layer 24REM, which is the first functional layer formed on the bank 23, is thicker than the film thickness of the portion other than the end portion 24REME of the red light-emitting layer 24REM formed on the bank 23. The red light-emitting layer 24REM, which is the first functional layer formed to have a thick film thickness, has a high resistance due to its thick film thickness, and therefore, it is possible to further suppress the leakage current from flowing through the region LP described above.

[0048] In this embodiment, the first medium material MR1 of the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, and the first medium material MR1 of the second portion 24REM2 of the red light-emitting layer 24REM are the same component, octanethiol, as described above. However, the present invention is not limited to this, and as in a fourth embodiment described below, the first medium material MR1 of the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, and the first medium material MR1 of the second portion 24REM2 of the red light-emitting layer 24REM may be at least partially different from each other.

[0049] Fig. 5 is a diagram showing a part of the process of forming the red light-emitting layer 24REM provided in the red light-emitting element 5R shown in Fig. 3. Fig. 6 is a diagram showing the remaining part of the process of forming the red light-emitting layer 24REM provided in the red light-emitting element 5R shown in Fig. 3. The process of forming the red light-emitting layer 24REM shown in Fig. 5 and Fig. 6 is a process of forming the red light-emitting layer 24REM using a lift-off method. Here, a method of forming the red light-emitting layer 24REM will be described as an example of a method of forming a functional layer, but the method is not limited to this.

[0050] As shown in STEP 1 of FIG. 5 , for example, a resist film PR is first formed on the entire surface of the hole transport layer 24H, which is formed over the entire display area DA shown in FIG. 1 and is provided as a common layer for the subpixels RSP, GSP, and BSP of each color. Then, a portion PR′ of the resist film PR is exposed using a mask MA. The exposed portion PR′ of the resist film PR corresponds to the region where the red light-emitting layer 24REM is to be formed. In this embodiment, a positive resist film is used as the resist film PR as an example, but this is not limiting; a negative resist film may also be used as the resist film PR. As shown in STEP 2 of FIG. 5 , the resist film PR is developed using an alkaline developer DPS. The exposed portion PR′ of the resist film PR is removed, while the unexposed portion of the resist film PR is left. As shown in STEP 3 of FIG. 5 , a resist film PR having an opening KKP is obtained. The alkaline developer DPS may contain additives such as surfactants to enhance its ability to remove exposed resist films. Then, as shown in STEP 4 of FIG. 5 , a mixed solution containing quantum dots QD1 (a first functional material having a core material composed of InP and a shell material composed of a metal sulfide (e.g., zinc sulfide (ZnS))) and octanethiol (a first medium material MR1) and a solvent was applied using, for example, a spin coater or slit coater to form a red light-emitting layer 24REMP (a first functional layer) on the resist film PR and on the hole transport layer 24H exposed through the openings KKP of the resist film PR. The red light-emitting layer 24REMP (a first functional layer) is then subjected to the heat treatment shown in STEP 7 of FIG. 6 to become the red light-emitting layer 24REM (a first functional layer). 5, a meniscus is generated by surface tension near the side surface of the resist film PR at the opening portion KKP of the resist film PR, resulting in a portion 24REMPT where the red light-emitting layer 24REMP is formed thick. Therefore, the red light-emitting layer 24REMP is formed so that the film thickness of the red light-emitting layer 24REMP formed at the edge of the opening portion KKP is thicker than the film thickness of the red light-emitting layer 24REMP formed in the center of the opening portion KKP.Then, as shown in STEPs 5 and 6 of FIG. 6 , a process was performed in which the amount of octanethiol contained in the first medium material MR1 contained in the first portion of the red-light-emitting layer 24REMP, which is the first functional layer and forms the light-emitting region HR, was reduced to be less than the amount of octanethiol contained in the second portion of the red-light-emitting layer 24REMP, which is the first functional layer and forms the non-light-emitting region NHR. STEP 5 of FIG. 6 is a first cleaning process for the red-light-emitting layer 24REMP, which is the first functional layer, and a stripping process for the resist film PR using a stripping solvent PRS for the resist film PR. Generally, since the resist film PR is highly polar, when a lift-off process is considered, the stripping solvent PRS can be, for example, a polar solvent such as PGMEA. The stripping solvent PRS may contain an additive such as a surfactant to enhance the removal power of the resist film PR. The red-light-emitting layer 24REMP, which is the first functional layer, contains quantum dots QD1, which are a first functional material with octanethiol, a first medium material MR1, coordinated to the surface, and octanethiol, a first medium material MR1, existing alone. The quantum dots QD1 are not dispersed in the polar solvent PGMEA because the low-polarity alkyl chains of the octanethiol are coordinated toward the surface. On the other hand, octanethiol existing alone dissolves in the polar solvent PGMEA. In the relatively thin portion of the red-light-emitting layer 24REMP, the polar solvent PGMEA permeates the entire layer, so the PGMEA can remove most of the octanethiol, a first medium material MR1, existing alone. However, as described above, the quantum dots QD1 do not disperse in PGMEA and remain intact. On the other hand, in the portion 24REMPT where the red light-emitting layer 24REMP is formed thick, PGMEA penetrates only near the surface of the layer and cannot penetrate deep into the layer, so that the octanethiol, which is the first medium material MR1 present alone near the surface of the layer, can be almost completely removed, but the quantum dots QD1 do not disperse in the PGMEA and remain as they are.In the layer, both the octanethiol, which is the first medium material MR1 present alone, and the quantum dots QD1 remain as they are.The red-light-emitting layer 24REMP formed at the edge of the opening portion KKP of the resist film PR becomes the second portion 24REM2 of the red-light-emitting layer 24REM, and the red-light-emitting layer 24REMP formed in the center of the opening portion KKP of the resist film PR becomes the first portion 24REM1 of the red-light-emitting layer 24REM. STEP 6 in FIG. 6 is a second cleaning step of the red-light-emitting layer 24REMP (the first functional layer) using a cleaning solvent CLS, which is performed after the first cleaning step of the red-light-emitting layer 24REMP (the first functional layer) and the stripping step of the resist film PR shown in STEP 5 in FIG. 6 . This second cleaning step is preferably performed when the octanethiol (first medium material MR1) present in a simple form is not sufficiently removed during the first cleaning step of the red-light-emitting layer 24REMP and the stripping step of the resist film PR, and may be omitted as appropriate. The cleaning solvent CLS may be, for example, a polar solvent, PGMEA. Thereafter, as shown in STEP 7 of Fig. 6, a heat treatment is performed to remove the peeling solvent PRS and the cleaning solvent CLS, and as shown in STEP 8 of Fig. 6, the red light-emitting layer 24REM included in the red light-emitting element 5R shown in Fig. 3 can be formed. Note that the heat treatment shown in STEP 7 of Fig. 6 may be omitted as appropriate.

[0051] As described above, in this embodiment, the first medium material MR1 contained in the red-light-emitting layer 24REM, which is the first functional layer, is octanethiol, and the first functional material contained in the red-light-emitting layer 24REM, which is the first functional layer, is quantum dots QD1. However, the first functional layer may be a layer other than an emissive layer, for example, any one of a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer. Furthermore, as long as the solvent treatment can disperse and dissolve only the first medium material MR1 in a specific region of the first functional layer without dispersing or dissolving the first functional material itself, the first medium material MR1 and the first functional material are not particularly limited, and the first functional material is not limited to particles or nanoparticles. The solvent used in the solvent treatment can be appropriately selected from, for example, organic solvents, aqueous solutions, etc., taking into account the polarity of the first medium material MR1 and the first functional material.

[0052] Below, as an example of a first functional layer that can be formed in the same manner as the formation process of the red light-emitting layer 24REM using the lift-off method described based on Figures 5 and 6, we will explain a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer that include a first portion formed in the light-emitting region HR and a second portion formed in the non-light-emitting region NHR.

[0053] The first functional layer may be at least one of a hole transport layer and a hole injection layer. In this case, the first functional material contained in at least one of the hole transport layer and the hole injection layer may be hole transport nanoparticles, and the first medium material MR1 contained in at least one of the hole transport layer and the hole injection layer may be a dispersion material for the hole transport nanoparticles. Examples of the hole transport nanoparticles include NiO, CuI, CuO, CoO, CrO, and CuAlS. For example, when NiO is used as the hole transport nanoparticles, the dispersion material for the hole transport nanoparticles may be, for example, Me-2PACz, a phosphonic acid-based dispersant. The first functional layer may be a hole transport layer, and the second functional layer, which is larger than the first portion of the hole transport layer in a planar view, may be, for example, a hole injection layer provided as a common layer for each color subpixel.

[0054] The first functional layer may be at least one of an electron transport layer and an electron injection layer. In this case, the first functional material contained in at least one of the electron transport layer and the electron injection layer may be electron transport nanoparticles, and the first medium material MR1 contained in at least one of the electron transport layer and the electron injection layer may be a dispersion material for the electron transport nanoparticles. Examples of the electron transport nanoparticles include ZnO, ZnS, ZrO, MgZnO, AlZnO, and TiO2. For example, when ZnO is used as the electron transport nanoparticles, the dispersion material for the electron transport nanoparticles may be, for example, monoethanolamine, an amine-based dispersant. The first functional layer is an electron transport layer, and the second functional layer, which is formed larger than the first portion of the electron transport layer in a planar view, may be, for example, an electron injection layer provided as a layer common to the subpixels of each color. As described above, the first functional material is explained here as an example of particles such as hole-transporting nanoparticles or electron-transporting nanoparticles, but this is not limited to this, and the first functional material may be, for example, a hole-transporting polymer material or an electron-transporting polymer material. In this case, for example, a carboxylic acid-based dispersant, a thiol-based dispersant, or an amine-based dispersant can be used as the first medium material MR1.

[0055] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Figures 7 to 9. Figure 7 is a cross-sectional view showing a schematic configuration of a red light emitting element 5Ra provided in a display device of the second embodiment.

[0056] As shown in FIG. 7, in the red light emitting layer 24REM provided in the red light emitting element 5Ra, the average film thickness of the second portion 24REM2 of the red light emitting layer 24REM is equal to or smaller than the average film thickness of the first portion 24REM1 of the red light emitting layer 24REM.

[0057] FIG. 8 is a diagram showing an example of a process for forming the red light-emitting layer 24REM provided in the red light-emitting element 5Ra shown in FIG.

[0058] As shown in STEP 11 of FIG. 8 , first, for example, a first functional layer, a red light-emitting layer 24REMP, is formed by dropping, using, for example, an inkjet method, a mixed solution containing quantum dots QD1, a first functional material having a core material composed of InP and a shell material composed of a metal sulfide (e.g., zinc sulfide (ZnS)), and octanethiol and a solvent, only in the region corresponding to the red subpixel RSP on the hole transport layer 24H formed over the entire display area DA shown in FIG. 1 and provided as a common layer for the subpixels RSP, GSP, and BSP of each color. Subsequently, a resist film PR is formed over the entire surface, and then a portion PR′ of the resist film PR is exposed using a mask MA. The exposed portion PR′ of the resist film PR corresponds to the central portion of the red light-emitting layer 24REMP. As shown in STEP 12 of Fig. 8, the resist film PR is developed using an alkaline developer DPS, and a portion of the exposed resist film PR' is removed while the unexposed resist film PR is left, thereby obtaining a resist film PR having an opening portion KKP. Then, as shown in STEP 13 of Fig. 8, a process is performed in which the amount of octanethiol contained in the first medium material MR1 contained in the first portion of the red-light-emitting layer 24REMP, which is the first functional layer and which forms the light-emitting region HR, is reduced to be less than the amount of octanethiol contained in the second portion of the red-light-emitting layer 24REMP, which is the first functional layer and which forms the non-light-emitting region NHR. The process shown in STEP 13 of Fig. 8 is a first cleaning process of the red-light-emitting layer 24REMP, which is the first functional layer, and a stripping process of the resist film PR using a stripping solvent PRS for the resist film PR. In the part of the red light-emitting layer 24REMP that is not covered by the resist film PR, the polar solvent PGMEA penetrates the entire layer, so that the PGMEA can remove most of the octanethiol, which is the first medium material MR1 that exists alone, but the quantum dots QD1 do not disperse in the PGMEA and therefore remain as they are.On the other hand, in the portion of the red light-emitting layer 24REMP covered with the resist film PR, PGMEA penetrates the resist film PR, allowing the resist film PR to be peeled off, but it can only penetrate up to the surface of the red light-emitting layer 24REMP, so that the octanethiol, which is the first medium material MR1 present alone, and the quantum dots QD1 remain in the red light-emitting layer 24REMP. Thereafter, a heat treatment as shown in STEP 7 of Figure 6 is performed to remove the peeling solvent PRS, thereby forming the red light-emitting layer 24REM provided in the red light-emitting element 5Ra shown in Figure 7. The heat treatment as shown in STEP 7 of Figure 6 can also be omitted as appropriate.

[0059] FIG. 9 is a diagram showing another example of a process for forming the red light-emitting layer 24REM provided in the red light-emitting element 5Ra shown in FIG.

[0060] As shown in STEP 21 of Figure 9, first, for example, only in the region corresponding to the red sub-pixel RSP on the hole transport layer 24H formed over the entire surface of the display area DA shown in Figure 1 and provided as a common layer in the sub-pixels RSP, GSP, and BSP of each color, a mixed solution containing quantum dots QD1, which are the first functional material having a core material composed of InP and a shell material composed of a metal sulfide (e.g., zinc sulfide (ZnS)), and a decomposable compound that decomposes when energy is applied and a solvent that constitutes the first medium material MR1', is dropped using, for example, an inkjet method to form a red light-emitting layer 24REMPa, which is the first functional layer. 9 , a mask MA is used to expose a central portion of the red light-emitting layer 24REMPa, which is the first functional layer, through an opening MAK of the mask MA, and energy is applied to the central portion of the red light-emitting layer 24REMPa, which is the first functional layer, thereby decomposing and removing a larger amount of the decomposable compound, which is the first medium material MR1′, contained in the first portion of the red light-emitting layer 24REMPa, which is the first functional layer, than the decomposable compound, which is the first medium material MR1′, contained in the second portion of the red light-emitting layer 24REMPa, which is the first functional layer. Note that, as the decomposable compound, for example, xanthogenic acid or a silica-based decomposable compound can be used as the first medium material MR1′.

[0061] 7, which includes the red light-emitting layer 24REM formed by the method shown in FIG. 9, in the cross section of the red light-emitting layer 24REM, which is the first functional layer, the total area of ​​the decomposable compound contained in the second region HD of the second portion 24REM2 is larger than the total area of ​​the decomposable compound contained in the first region LD of the first portion 24REM1. Note that the second region HD and the first region LD have the same size. For example, the first region LD and the second region HD, which are the same size, may each have the smaller size of the first portion 24REM1 or the second portion 24REM2 in the cross section.

[0062] 7, which is the first functional layer of the red light-emitting element 5Ra having the red light-emitting layer 24REM formed by the method shown in FIG. 9, the concentration of the decomposable compound contained in the second unit having a predetermined volume of the second portion 24REM2 is higher than the concentration of the decomposable compound contained in the first unit having the predetermined volume of the first portion 24REM1. Note that the volumes of the first unit and the second unit are the same. For example, each of the first unit and the second unit may have a smaller volume of the first portion 24REM1 or the second portion 24REM2.

[0063] In the red light-emitting element 5Ra including the red light-emitting layer 24REM as the first functional layer described above, and in a display device including the red light-emitting element 5Ra, the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second region HD of a predetermined size in the second portion 24REM2 formed in the non-light-emitting region NHR is larger than the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first region LD of the predetermined size in the first portion 24REM1 formed in the light-emitting region HR. Alternatively, the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second unit having a predetermined volume in the second portion 24REM2 formed in the non-light-emitting region NHR is higher than the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first unit having the predetermined volume in the first portion 24REM1 formed in the light-emitting region HR. Therefore, it is possible to suppress leakage current in the red light-emitting layer 24REM, which is the first functional layer formed in the non-light-emitting region NHR, and thus it is possible to suppress the expression of the specific function of the first functional material in the second portion 24REM2, which is a part of the red light-emitting layer 24REM, which is the first functional layer.

[0064] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view showing a schematic configuration of a red light-emitting element 5Rb provided in a display device of the third embodiment.

[0065] 10 , the red light-emitting element 5Rb does not have a bank 23. Because the red light-emitting element 5Rb does not have a bank 23, the light-emitting region HR is a region where the first electrode 22 and the second electrode 25 overlap in a planar view. On the other hand, the red light-emitting elements 5R and 5Ra described in the first and second embodiments have the bank 23, so the light-emitting region HR is a region where the bank 23 is not provided and is a region where the first electrode 22 and the second electrode 25 overlap in a planar view.

[0066] The red light-emitting layer 24REM, which is the first functional layer provided in the red light-emitting element 5Rb shown in Figure 10, can be formed in the same manner as the formation process of the red light-emitting layer 24REM using the lift-off method described based on Figures 5 and 6.

[0067] In a display device including the red light-emitting element 5Rb having a red light-emitting layer 24REM as a first functional layer, the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second region HD of a predetermined size in the second portion 24REM2 formed in the non-light-emitting region NHR is larger than the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first region LD of a predetermined size in the first portion 24REM1 formed in the light-emitting region HR. Alternatively, the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second unit having a predetermined volume in the second portion 24REM2 formed in the non-light-emitting region NHR is higher than the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first unit having the predetermined volume in the first portion 24REM1 formed in the light-emitting region HR. Therefore, leakage current in the red light-emitting layer 24REM as a first functional layer formed in the non-light-emitting region NHR can be suppressed. That is, in the second portion 24REM2, which is a part of the red light-emitting layer 24REM, which is the first functional layer, it is possible to suppress the expression of the specific function of the first functional material.

[0068] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a cross-sectional view showing a schematic configuration of a red light emitting element 5Rc provided in a display device of the fourth embodiment.

[0069] The red light-emitting layer 24REM included in the red light-emitting element 5Rc shown in FIG. 11 includes a polymeric material, which is a first medium material MR1. In a cross section of the red light-emitting layer 24REM, which is the first functional layer, the total area of ​​the polymeric material, which is the first medium material MR1, included in the second region HD of a predetermined size in the second portion 24REM2 is larger than the total area of ​​the polymeric material, which is the first medium material MR1, included in the first region LD of the predetermined size in the first portion 24REM1. Note that the second region HD and the first region LD are the same size. For example, the first region LD and the second region HD, which are the same size, may each have the smaller of the size of the first portion 24REM1 and the size of the second portion 24REM2 in the cross section.

[0070] 11 , the second unit portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer included in the red light-emitting element 5Rc, has a second unit portion having a predetermined volume, and the second unit portion has a higher concentration of the polymer material serving as the first medium material MR1 than the first unit portion having the predetermined volume of the first unit portion 24REM1. The volumes of the first unit portion and the second unit portion are the same. For example, each of the first unit portion and the second unit portion may have a smaller volume of the first unit portion 24REM1 or the second unit portion 24REM2.

[0071] In this embodiment, the red light emitting element 5Rc that does not include the bank 23 will be described as an example, but the present invention is not limited to this and the bank 23 may be included.

[0072] Fig. 12 is a diagram showing an example of a process for forming the red light-emitting layer 24REM provided in the red light-emitting element 5Rc shown in Fig. 11. The process for forming the red light-emitting layer 24REM shown in Fig. 12 is a process for forming the red light-emitting layer 24REM using a lift-off method.

[0073] The process shown in STEP 31 of Fig. 12 corresponds to the process shown in STEP 4 of Fig. 5, and the processes shown in STEP 1 to STEP 3 of Fig. 5 are performed before the process shown in STEP 31 of Fig. 12. Although a detailed description thereof will be omitted, the process shown in STEP 31 of Fig. 12 uses a mixed solution different from the mixed solution used in the process shown in STEP 4 of Fig. 5, which contains quantum dots QD1 as a first functional material having a core material composed of InP and a shell material composed of a metal sulfide (e.g., zinc sulfide (ZnS)), a cross-linkable polymer material constituting a first medium material MR1, and a solvent. 12 , a mask (not shown) was used to selectively expose the portion 24REMPbT where the red light-emitting layer 24REMPb was formed thick, thereby crosslinking the crosslinkable polymer material contained in the portion 24REMPbT where the red light-emitting layer 24REMPb was formed thick, which becomes the second portion 24REM2 of the red light-emitting layer 24REM as the first functional layer, more than the crosslinkable polymer material contained in the red light-emitting layer 24REMPb which becomes the first portion 24REM1 of the red light-emitting layer 24REM as the first functional layer. Then, as shown in STEP 33 of FIG. 12 , the red light-emitting layer 24REMPb as the first functional layer was washed with a solvent, in this embodiment, the stripping solvent PRS for the resist film PR. A first cleaning step for the red light-emitting layer 24REMPb as the first functional layer and a stripping step for the resist film PR were performed, followed by a heat treatment, thereby forming the red light-emitting layer 24REM as the first functional layer. In the first cleaning process of the red light-emitting layer 24REMPb, which is the first functional layer, and the stripping process of the resist film PR, in the portion 24REMPbT where the red light-emitting layer 24REMPb, which is the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, is formed thick, the cross-linkable polymer material is cross-linked to form a polymer material with a large molecular weight, and therefore the stripping solvent PRS for the resist film PR cannot penetrate, but in the red light-emitting layer 24REMPb, which is the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, the cross-linkable polymer material is hardly cross-linked, and therefore the stripping solvent PRS for the resist film PR can penetrate and remove most of the cross-linkable polymer material.11 , in the cross section of the red light-emitting layer 24REM serving as the first functional layer, the total area of ​​the polymer material serving as the first medium MR1 included in the second region HD of a predetermined size in the second portion 24REM2 is greater than the total area of ​​the polymer material serving as the first medium MR1 included in the first region LD of the predetermined size in the first portion 24REM1. Also, the concentration of the polymer material serving as the first medium MR1 included in the second unit of a predetermined volume in the second portion 24REM2 of the red light-emitting layer 24REM serving as the first functional layer is higher than the concentration of the polymer material serving as the first medium MR1 included in the first unit of a predetermined volume in the first portion 24REM1.

[0074] In the present embodiment, as described above, the case where the red light-emitting layer 24REMPb, which is the first functional layer, is selectively exposed to light and then washed with the stripping solvent PRS for the resist film PR is used as an example. However, in the case of a process for forming the red light-emitting layer 24REM using a lift-off method, the red light-emitting layer 24REMPbT, which is the first functional layer, is formed thickly, is generated. Therefore, the stripping solvent PRS for the resist film PR does not easily penetrate into the red light-emitting layer 24REMPbT, and the crosslinkable polymer material contained in the red light-emitting layer 24REMPbT, which is the first functional layer, is difficult to remove. Therefore, the red light-emitting layer 24REMPbT, which is the first functional layer, may be selectively exposed to light after the process for cleaning the red light-emitting layer 24REMPb, which is the first functional layer, with the stripping solvent PRS for the resist film PR is first performed.

[0075] Furthermore, in this embodiment, the case where the red light-emitting layer 24REM is formed using the lift-off method has been described as an example, but the method is not limited to the lift-off method. For example, in the case of a configuration provided with a bank, the red light-emitting layer 24REMPb, which is the first functional layer, may be formed using the inkjet method, and then the cross-linkable polymer material contained in the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer, may be cross-linked more than the cross-linkable polymer material contained in the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, and then the red light-emitting layer 24REMPb, which is the first functional layer, may be washed with a cleaning solvent.

[0076] 12, the first medium material of the first portion 24REM1 of the red light-emitting layer 24REM and the first medium material of the second portion 24REM2 of the red light-emitting layer 24REM are at least partially different from each other. That is, the first medium material of the second portion 24REM2 of the red light-emitting layer 24REM is mainly composed of a polymer material obtained by cross-linking a cross-linkable polymer material, while the first medium material of the first portion 24REM1 of the red light-emitting layer 24REM is mainly composed of a cross-linkable polymer material.

[0077] In a display device including the red light-emitting element 5Rc having a red light-emitting layer 24REM as a first functional layer, the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second region HD of a predetermined size in the second portion 24REM2 formed in the non-light-emitting region NHR is larger than the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first region LD of a predetermined size in the first portion 24REM1 formed in the light-emitting region HR. Alternatively, the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second unit having a predetermined volume in the second portion 24REM2 formed in the non-light-emitting region NHR is higher than the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first unit having the predetermined volume in the first portion 24REM1 formed in the light-emitting region HR. Therefore, leakage current in the red light-emitting layer 24REM as a first functional layer formed in the non-light-emitting region NHR can be suppressed. That is, in the second portion 24REM2, which is a part of the red light-emitting layer 24REM, which is the first functional layer, it is possible to suppress the expression of the specific function of the first functional material.

[0078] Next, a fifth embodiment of the present disclosure will be described with reference to Fig. 13. The red light-emitting element 5Rd included in the display device of this embodiment differs from the red light-emitting element 5Ra described in the second embodiment in that the red light-emitting element 5Rd decomposes and removes the decomposable compound in the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer formed in the light-emitting region HR, by applying current and aging.

[0079] FIG. 13 is a diagram showing an example of a process for forming the red light-emitting layer 24REM of the red light-emitting element 5Rd provided in the display device of the fifth embodiment.

[0080] 13 , a mixed solution containing quantum dots as a first functional material having a core material composed of InP and a shell material composed of a metal sulfide (e.g., zinc sulfide (ZnS)), a decomposable compound that decomposes upon energy application and a solvent that constitutes a first medium material is dropped, for example, using an inkjet method, and then heat treatment is performed to form a red light-emitting layer 24REMPc as a first functional layer provided in the red light-emitting element 5Rd′. Thereafter, the decomposable compound in the first portion 24REM1 of the red light-emitting layer 24REM as a first functional layer formed in the light-emitting region HR is decomposed and removed by applying current to the first electrode 22 and the second electrode 25 provided in the red light-emitting element 5Rd′. On the other hand, during the period in which the decomposable compound in the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer formed in the light-emitting region HR, is decomposed and removed by electrical aging using the first electrode 22 and the second electrode 25, no current flows in the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer formed in the non-light-emitting region NHR, to the extent that it flows during the above-mentioned electrical aging, and the decomposable compound is not removed. Note that, as the decomposable compound, which is the first medium material, for example, xanthogenic acid or a silica-based decomposable compound can be used.

[0081] In a display device including the red light-emitting element 5Rd having a red light-emitting layer 24REM as a first functional layer, the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second region HD of a predetermined size in the second portion 24REM2 formed in the non-light-emitting region NHR is larger than the area of ​​the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first region LD of a predetermined size in the first portion 24REM1 formed in the light-emitting region HR. Alternatively, the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the second unit having a predetermined volume in the second portion 24REM2 formed in the non-light-emitting region NHR is higher than the concentration of the first medium material MR1 having a higher insulating property than the quantum dots QD1 in the first unit having the predetermined volume in the first portion 24REM1 formed in the light-emitting region HR. Therefore, leakage current in the red light-emitting layer 24REM as a first functional layer formed in the non-light-emitting region NHR can be suppressed. That is, in the second portion 24REM2, which is a part of the red light-emitting layer 24REM, which is the first functional layer, it is possible to suppress the expression of the specific function of the first functional material.

[0082] Sixth Embodiment Next, a sixth embodiment of the present disclosure will be described with reference to Fig. 14. Fig. 14 is a cross-sectional view showing a schematic configuration of a red light emitting element 5Re provided in a display device of the sixth embodiment.

[0083] As shown in FIG. 14 , the red light-emitting element 5Re includes an insertion layer 24IL between the first electrode 22 and the second electrode 25, which overlaps at least the red light-emitting layer 24REM, which is the first functional layer, in a planar view. The insertion layer 24IL has an electrical conductivity equal to or lower than the electrical conductivity of the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer. In this embodiment, the insertion layer 24IL is formed over the entire display area DA shown in FIG. 1 . However, this is not limiting. For example, the insertion layer 24IL may be formed so as to overlap only the red light-emitting layer 24REM, which is the first functional layer, in a planar view. The insertion layer 24IL may be formed of the same material as the first medium material contained in the red light-emitting layer 24REM. For example, the insertion layer 24IL may be a layer made of a metal sulfide (e.g., zinc sulfide (ZnS)) or a layer made of silicon oxide. When the insertion layer 24IL is formed of the same material as the first medium material contained in the red light-emitting layer 24REM, in the case of an inorganic material, the crystallinity of the insertion layer 24IL and the first medium material contained in the red light-emitting layer 24REM can be matched to reduce carrier traps. The insertion layer 24IL has functions such as replenishing the first medium material deficiency caused by desorption of the first medium material contained in the red light-emitting layer 24REM, improving the carrier balance in the red light-emitting element 5Re, and protecting the lower layer during the formation of the upper layer. Incidentally, when the insertion layer 24IL has high carrier mobility, crosstalk between adjacent light-emitting elements can be suppressed. The insertion layer 24IL may be formed, for example, by vapor deposition or by patterning using a lift-off method. In addition, the insertion layer 24IL may be formed in three different steps, for example, by forming the first insertion layer after forming the red light-emitting layer, forming the second insertion layer after forming the green light-emitting layer, and forming the third insertion layer after forming the blue light-emitting layer, or may be formed in one step after forming the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer.

[0084] Seventh Embodiment Next, a seventh embodiment of the present disclosure will be described with reference to Fig. 15. Fig. 15 is a cross-sectional view showing a schematic configuration of a red light emitting element 5Rf and a green light emitting element 5Ga provided in a display device of the seventh embodiment.

[0085] 15, each of the red light-emitting element 5Rf and the green light-emitting element 5Ga includes a bank 23' formed in an uneven shape. In the red light-emitting element 5Rf, an end 24REME of the red light-emitting layer 24REM, which is the first functional layer, is located on a recess 23b of the uneven bank 23', and in the green light-emitting element 5Ga, an end 24GEME of the green light-emitting layer 24GEM, which is the first functional layer, is located on a recess 23b of the uneven bank 23'. Although not limited to this and not shown, in the red light emitting element 5Rf, the end 24REME of the red light emitting layer 24REM, which is the first functional layer, may be located on the side surfaces 23as, 23as' of the protrusions 23a of the unevenly shaped bank 23', and in the green light emitting element 5Ga, the end 24GEME of the green light emitting layer 24GEM, which is the first functional layer, may be located on the side surfaces 23as, 23as' of the protrusions 23a of the unevenly shaped bank 23'. Note that in the red light emitting element 5Rf, the opening ELr of the bank 23' is the light emitting region, and in the green light emitting element 5Ga, the opening ELg of the bank 23' is the light emitting region.

[0086] In a display device including a red light-emitting element 5Rf having a red light-emitting layer 24REM as a first functional layer and a green light-emitting element 5Ga having a green light-emitting layer 24GEM as a first functional layer, and the red light-emitting element 5Rf and the green light-emitting element 5Ga, the area of ​​the first medium material MR1 having higher insulating properties than the quantum dots QD1 in a second region HD of a predetermined size of the second portion 24REM2 / 24GEM2 formed in the non-emitting region NHR is larger than the area of ​​the first medium material MR1 having higher insulating properties than the quantum dots QD1 in the first region LD of a predetermined size of the first portion 24REM1 / 24GEM1 formed in the emitting region HR. Alternatively, the concentration of the first medium material MR1, which has higher insulating properties than the quantum dots QD1 in the second units having a predetermined volume in the second portions 24REM2 and 24GEM2 formed in the non-light-emitting region NHR, is higher than the concentration of the first medium material MR1, which has higher insulating properties than the quantum dots QD1 in the first units having the predetermined volume in the first portions 24REM1 and 24GEM1 formed in the light-emitting region HR. Therefore, leakage current can be suppressed in the red light-emitting layer 24REM and the green light-emitting layer 24GEM, which are the first functional layers formed in the non-light-emitting region NHR. That is, the expression of a specific function possessed by the first functional material can be suppressed in the second portion 24REM2, which is a part of the red light-emitting layer 24REM, and the second portion 24GEM2, which is a part of the green light-emitting layer 24GEM, which are the first functional layers.

[0087] Eighth Embodiment Next, an eighth embodiment of the present disclosure will be described with reference to Fig. 16. Fig. 16 is a cross-sectional view showing a schematic configuration of a red light emitting element 5Rg provided in a display device of the eighth embodiment.

[0088] 16 , the red light emitting element 5Rg includes a bank 23, a first electrode 22 serving as a light reflective layer located above the bank 23, and a red light emitting layer 24REM serving as a first functional layer located above the first electrode 22 serving as a light reflective layer. In this embodiment, the first electrode 22 is formed of a metal material such as Al so that the first electrode 22 serves as a light reflective layer.

[0089] In a red light emitting element 5Rg including a red light emitting layer 24REM as a first functional layer, and in a display device including the red light emitting element 5Rg, light emitted from a first portion 24REM1 of the red light emitting layer 24REM as the light emitting region HR can be efficiently reflected toward the display surface by utilizing the first electrode 22 as a light reflective layer formed on the side surface of the bank 23. In addition, the area of ​​the first medium material MR1 having higher insulating properties than the quantum dots QD1 in a second region HD of a predetermined size in the second portion 24REM2 formed in the non-light emitting region NHR is larger than the area of ​​the first medium material MR1 having higher insulating properties than the quantum dots QD1 in a first region LD of the predetermined size in the first portion 24REM1 formed in the light emitting region HR. Alternatively, the concentration of the first medium material MR1, which has a higher insulating property than the quantum dots QD1 in the second unit having a predetermined volume in the second portion 24REM2 formed in the non-light-emitting region NHR, is higher than the concentration of the first medium material MR1, which has a higher insulating property than the quantum dots QD1 in the first unit having the predetermined volume in the first portion 24REM1 formed in the light-emitting region HR. Therefore, leakage current in the red-light-emitting layer 24REM, which is the first functional layer formed in the non-light-emitting region NHR, can be suppressed. That is, the expression of a specific function possessed by the first functional material can be suppressed in the second portion 24REM2, which is a part of the red-light-emitting layer 24REM, which is the first functional layer.

[0090] Next, a ninth embodiment of the present disclosure will be described with reference to Fig. 17 and Fig. 18. Fig. 17 is a plan view showing a schematic configuration of a display device 1a of the ninth embodiment. Fig. 18 is a diagram showing a schematic configuration of a display area DA of the display device 1a of the ninth embodiment, and is a cross-sectional view taken along line AA' of the display device 1a shown in Fig. 17.

[0091] 17 and 18 , the display device 1a includes a plurality of light-emitting elements, some of which are red light-emitting elements 5R serving as first light-emitting elements, some of which are green light-emitting elements 5G serving as second light-emitting elements, and the remaining of which are blue light-emitting elements 5B serving as third light-emitting elements. The red light-emitting element 5R serving as the first light-emitting element includes a red light-emitting layer 24REM serving as a first functional layer having a first portion 24REM1 and a second portion 24REM2, the green light-emitting element 5G serving as the second light-emitting element includes a green light-emitting layer 24GEM serving as a third functional layer having a first portion 24GEM1 and a second portion 24GEM2, and the blue light-emitting element 5B serving as the third light-emitting element includes a blue light-emitting layer 24BEM serving as a fourth functional layer having a first portion 24BEM1 and a second portion 24BEM2. A part of the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer of the red light-emitting element 5R, is laminated with the second portion 24BEM2 of the blue light-emitting layer 24BEM, which is the fourth functional layer of the blue light-emitting element 5B, and another part of the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer of the red light-emitting element 5R, is laminated with the second portion 24GEM2 of the green light-emitting layer 24GEM, which is the third functional layer of the green light-emitting element 5G. Also, a part of the second portion 24GEM2 of the green light-emitting layer 24GEM, which is the third functional layer of the green light-emitting element 5G, is laminated with the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer of the red light-emitting element 5R, and another part of the second portion 24GEM2 of the green light-emitting layer 24GEM, which is the third functional layer of the green light-emitting element 5G, is laminated with the second portion 24BEM2 of the blue light-emitting layer 24BEM, which is the fourth functional layer of the blue light-emitting element 5B. In addition, a part of the second portion 24BEM2 of the blue light-emitting layer 24BEM, which is the fourth functional layer of the blue light-emitting element 5B, is stacked with the second portion 24REM2 of the red light-emitting layer 24REM, which is the first functional layer of the red light-emitting element 5R, and another part of the second portion 24BEM2 of the blue light-emitting layer 24BEM, which is the fourth functional layer of the blue light-emitting element 5B, is stacked with the second portion 24GEM2 of the green light-emitting layer 24GEM, which is the third functional layer of the green light-emitting element 5G.The third functional layer of the green light-emitting element 5G is a green light-emitting layer 24GEM containing quantum dots and a second medium material, which are second functional materials, and the fourth functional layer of the blue light-emitting element 5B is a blue light-emitting layer 24BEM containing quantum dots and a third medium material, which are third functional materials, will be described as an example, but is not limited to this. In this embodiment, the light-emitting layers of each color are formed in the order of red light-emitting layer 24REM, green light-emitting layer 24GEM, and blue light-emitting layer 24BEM, so that the stacking order of the second portions of different light-emitting layers is as shown in Figure 18, but is not limited to this, and the stacking order of the second portions of different light-emitting layers will change depending on the formation order of the light-emitting layers of each color.

[0092] According to the display device 1a, by stacking the second portions of different light-emitting layers on each other, it is possible to further suppress the leakage current from flowing into the non-light-emitting region NHR.

[0093] 19 and 20 , a display device 1b of the present embodiment including a red light-emitting element 5R, a green light-emitting element 5G, and a blue light-emitting element 5B differs from the display device 1a described in the 9th embodiment in that the second portion 24REM2 of the red light-emitting layer 24REM included in the red light-emitting element 5R, the second portion 24GEM2 of the green light-emitting layer 24GEM included in the green light-emitting element 5G, and the second portion 24BEM2 of the blue light-emitting layer 24BEM included in the blue light-emitting element 5B are stacked.

[0094] Fig. 19 is a diagram showing an example of a manufacturing process for the display device 1b of embodiment 10. Fig. 20 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1b of embodiment 10.

[0095] The manufacturing process of the display device 1b shown in Figure 19 will be described using an example in which the light-emitting layers of each color are formed in the order of red light-emitting layer 24REM, green light-emitting layer 24GEM, and blue light-emitting layer 24BEM, but the order in which the light-emitting layers of each color are formed is not limited to this. The process of forming the red light-emitting layer 24REM shown in Figure 19 is performed after a plurality of first electrodes 22 have been formed in the display area DA on the thin-film transistor layer 4 including the transistor TR shown in Figure 2, and a hole transport layer 24H has been formed over the entire display area DA. In this process, a first portion 24REM1 of the red light-emitting layer 24REM is formed in the area corresponding to the light-emitting region HR of the red light-emitting element 5R, and a second portion 24REM2 of the red light-emitting layer 24REM is formed in the area corresponding to the non-light-emitting region NHR of the red light-emitting element 5R, the area corresponding to the non-light-emitting region NHR of the green light-emitting element 5G, and the area corresponding to the non-light-emitting region NHR of the blue light-emitting element 5B. The formation process of the green light-emitting layer 24GEM shown in Figure 19 is performed after the formation process of the red light-emitting layer 24REM described above. In this process, a first portion 24GEM1 of the green light-emitting layer 24GEM is formed in the region corresponding to the light-emitting region HR of the green light-emitting element 5G. In the regions corresponding to the non-light-emitting region NHR of the red light-emitting element 5R, the region corresponding to the non-light-emitting region NHR of the green light-emitting element 5G, and the region corresponding to the non-light-emitting region NHR of the blue light-emitting element 5B, a second portion 24GEM2 of the green light-emitting layer 24GEM is formed on the second portion 24REM2 of the red light-emitting layer 24REM formed in the formation process of the red light-emitting layer 24REM described above. The formation process of the blue light-emitting layer 24BEM shown in Figure 19 is performed after the formation process of the green light-emitting layer 24GEM described above.In this process, a first portion 24BEM1 of the blue light-emitting layer 24BEM is formed in the region corresponding to the light-emitting region HR of the blue light-emitting element 5B, and in the region corresponding to the non-light-emitting region NHR of the red light-emitting element 5R, the region corresponding to the non-light-emitting region NHR of the green light-emitting element 5G, and the region corresponding to the non-light-emitting region NHR of the blue light-emitting element 5B, the second portion 24BEM2 of the blue light-emitting layer 24BEM is formed on a laminated film in which the second portion 24REM2 of the red light-emitting layer 24REM formed in the above-mentioned process of forming the red light-emitting layer 24REM and the second portion 24GEM2 of the green light-emitting layer 24GEM are laminated, and the second portion 24REM2 of the red light-emitting layer 24REM, the second portion 24GEM2 of the green light-emitting layer 24GEM, and the second portion 24BEM2 of the blue light-emitting layer 24BEM are laminated. On the other hand, a first portion 24REM1 of the red light-emitting layer 24REM is formed in the region corresponding to the light-emitting region HR of the red light-emitting element 5R, a first portion 24GEM1 of the green light-emitting layer 24GEM is formed in the region corresponding to the light-emitting region HR of the green light-emitting element 5G, and a first portion 24BEM1 of the blue light-emitting layer 24BEM is formed in the region corresponding to the light-emitting region HR of the blue light-emitting element 5B.

[0096] The display device 1b shown in Figure 20 is obtained by forming an electron transport layer 24E and a second electrode 25 over the entire display area DA after the step of forming the blue light-emitting layer 24BEM shown in Figure 19. Figure 20 is a cross-sectional view of the display device 1b taken along line B-B' in Figure 19. As shown in Figure 20, the display device 1b includes a laminate film 24LAM in which a second portion 24REM2 of the red light-emitting layer 24REM, a second portion 24GEM2 of the green light-emitting layer 24GEM, and a second portion 24BEM2 of the blue light-emitting layer 24BEM are stacked in each of the areas corresponding to the non-light-emitting regions NHR of the red light-emitting element 5R, the areas corresponding to the non-light-emitting regions NHR of the green light-emitting element 5G, and the areas corresponding to the non-light-emitting regions NHR of the blue light-emitting element 5B. Therefore, the laminate film 24LAM can further suppress leakage current from flowing into the non-light-emitting regions NHR.

[0097] Eleventh Embodiment Next, an eleventh embodiment of the present disclosure will be described with reference to Fig. 21. Fig. 21 is a cross-sectional view showing a schematic configuration of a display area DA of a display device 1c of the eleventh embodiment.

[0098] 21 , the red light-emitting element 5R included in the display device 1c includes a hole transport layer 24H, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and has a size equal to or larger than the first portion 24REM1 of the red light-emitting layer 24REM, which is a first functional layer, in a planar view. The green light-emitting element 5G included in the display device 1c includes a hole transport layer 24H, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and has a size equal to or larger than the first portion 24GEM1 of the green light-emitting layer 24GEM, which is a first functional layer, in a planar view. The blue light-emitting element 5B included in the display device 1c includes a hole transport layer 24H, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and has a size equal to or larger than the first portion 24BEM1 of the blue light-emitting layer 24BEM, which is a first functional layer, in a planar view. The hole transport layer 24H of the red light-emitting element 5R, the hole transport layer 24H of the green light-emitting element 5G, and the hole transport layer 24H of the blue light-emitting element 5B are each separated from one another and made of the same material.

[0099] According to the display device 1c, the hole transport layer 24H of the red light-emitting element 5R, the hole transport layer 24H of the green light-emitting element 5G, and the hole transport layer 24H of the blue light-emitting element 5B are each separated from one another, thereby preventing leakage current from flowing into the non-light-emitting region NHR.

[0100] Although not shown, the hole transport layer 24H provided in the red light-emitting element 5R, the hole transport layer 24H provided in the green light-emitting element 5G, and the hole transport layer 24H provided in the blue light-emitting element 5B are provided as a common layer, and in the hole transport layer 24H provided as a common layer, the region corresponding to the light-emitting region HR of each color is set as a first portion, and the region corresponding to the non-light-emitting region NHR is set as a second portion, and similar to the light-emitting layer, the conductivity of the second portion of the hole transport layer 24H may be made lower than the conductivity of the first portion of the hole transport layer 24H.

[0101] Next, a twelfth embodiment of the present disclosure will be described with reference to Fig. 22. A display device 1d of this embodiment including a red light-emitting element 5R, a green light-emitting element 5G, and a blue light-emitting element 5B differs from the display device 1c described in the eleventh embodiment in that the hole transport layer 24HR of the red light-emitting element 5R, the hole transport layer 24HG of the green light-emitting element 5G, and the hole transport layer 24HB of the blue light-emitting element 5B are separated from one another and made of different materials.

[0102] FIG. 22 is a cross-sectional view showing a schematic configuration of a display area DA of a display device 1d according to the twelfth embodiment.

[0103] 22 , the red light-emitting element 5R included in the display device 1d includes a hole transport layer 24HR, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and having a size equal to or larger than the first portion 24REM1 of the red light-emitting layer 24REM, which is a first functional layer, in a planar view. The green light-emitting element 5G included in the display device 1d includes a hole transport layer 24HG, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and having a size equal to or larger than the first portion 24GEM1 of the green light-emitting layer 24GEM, which is a first functional layer, in a planar view. The blue light-emitting element 5B included in the display device 1d includes a hole transport layer 24HB, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and having a size equal to or larger than the first portion 24BEM1 of the blue light-emitting layer 24BEM, which is a first functional layer, in a planar view. The hole transport layer 24HR of the red light emitting element 5R, the hole transport layer 24HG of the green light emitting element 5G, and the hole transport layer 24HB of the blue light emitting element 5B are each separated from one another and made of a different material. That is, in this embodiment, taking into consideration the injection of holes from the light emitting layer of each color, a hole transport layer made of a different material is used for each light emitting element of each color.

[0104] In the display device 1d, the hole transport layer 24HR of the red light-emitting element 5R, the hole transport layer 24HG of the green light-emitting element 5G, and the hole transport layer 24HB of the blue light-emitting element 5B are made of different materials in consideration of the injection of holes from the light-emitting layers of each color, thereby improving the hole injection efficiency in the light-emitting elements of each color. Furthermore, the hole transport layer 24HR of the red light-emitting element 5R, the hole transport layer 24HG of the green light-emitting element 5G, and the hole transport layer 24HB of the blue light-emitting element 5B are each separated from each other, thereby preventing leakage current from flowing into the non-light-emitting region NHR.

[0105] Next, a thirteenth embodiment of the present disclosure will be described with reference to Fig. 23. A display device 1e of this embodiment including a red light-emitting element 5R, a green light-emitting element 5G, and a blue light-emitting element 5B differs from the display devices 1a and 1b described in the ninth and tenth embodiments in that the hole transport layer 24H of the red light-emitting element 5R, the hole transport layer 24H of the green light-emitting element 5G, and the hole transport layer 24H of the blue light-emitting element 5B are separated from one another and made of the same material.

[0106] FIG. 23 is a cross-sectional view showing a schematic configuration of a display area DA of a display device 1e according to the thirteenth embodiment.

[0107] 23 , the red light-emitting element 5R included in the display device 1e includes a hole transport layer 24H, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and has a size equal to or larger than the first portion 24REM1 of the red light-emitting layer 24REM, which is the first functional layer, in a planar view. The green light-emitting element 5G included in the display device 1c includes a hole transport layer 24H, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and has a size equal to or larger than the first portion 24GEM1 of the green light-emitting layer 24GEM, which is the first functional layer, in a planar view. The blue light-emitting element 5B included in the display device 1c includes a hole transport layer 24H, which is a second functional layer, formed between the first electrode 22 and the second electrode 25 and has a size equal to or larger than the first portion 24BEM1 of the blue light-emitting layer 24BEM, which is the first functional layer, in a planar view. The hole transport layer 24H of the red light-emitting element 5R, the hole transport layer 24H of the green light-emitting element 5G, and the hole transport layer 24H of the blue light-emitting element 5B are each separated from one another and made of the same material.

[0108] According to the display device 1e, the hole transport layer 24H of the red light-emitting element 5R, the hole transport layer 24H of the green light-emitting element 5G, and the hole transport layer 24H of the blue light-emitting element 5B are each separated from one another, and a laminated film of a second portion of a light-emitting layer of a different color is formed in the non-light-emitting region NHR, thereby further suppressing leakage current from flowing into the non-light-emitting region NHR.

[0109] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0110] The present disclosure can be used in a light-emitting device, a display device, and a method for forming a functional layer.

[0111] 1, 1a to 1e Display device 4 Thin film transistor layer 5R, 5Ra to 5Rg Red light emitting element (light emitting element) 5G, 5Ga Green light emitting element (light emitting element) 5B Blue light emitting element (light emitting element) 22 First electrode 23 Bank 24R Functional layer including red light emitting layer 24G Functional layer including green light emitting layer 24B Functional layer including blue light emitting layer 24REM Red light emitting layer 24REM1 First portion of red light emitting layer 24REM2 Second portion of red light emitting layer 24REME End portion of red light emitting layer 24GEM Green light emitting layer 24GEM1 First portion of green light emitting layer 24GEM2 Second portion of green light emitting layer 24BEM Blue light emitting layer 24BEM1 First portion of blue light emitting layer 24BEM2 Second portion of blue light emitting layer 24LAM Stacked film 24H Hole transport layer 24E Electron transport layer 25 Second electrode 26, 28 Inorganic sealing film 27 Organic film 39 Functional film QD1 Quantum dot (first functional material) MR1 First medium material LD ​​First region HD Second region PIX Pixel RSP Red sub-pixel GSP Green sub-pixel BSP Blue sub-pixel DA Display region NDA Frame region HR Light-emitting region NHR Non-light-emitting region

Claims

1. A light-emitting element comprising: a first electrode; a second electrode; a first functional material; and a first functional layer formed between the first electrode and the second electrode, the first functional layer being larger in a planar view than the smaller of the first and second electrodes; wherein the first functional layer includes a first portion formed in a light-emitting region and a second portion formed in a non-light-emitting region; a first area is defined as the total area of ​​the first medium in first regions of a predetermined size included in the first portion in a cross section cut along the thickness direction of the first functional layer; a second area is defined as the total area of ​​the first medium in second regions of a predetermined size included in the second portion in the cross section; and the second portion includes the second region having the second area larger than the first area.

2. The light-emitting element described in claim 1, wherein the first medium material includes a polymer material, and in the cross section of the first functional layer, the total area of ​​the polymer material included in the second region is greater than the total area of ​​the polymer material included in the first region.

3. The light-emitting element described in claim 1, wherein the first medium material contains a decomposable compound that is decomposed by the application of energy, and in the cross section of the first functional layer, the total area of ​​the decomposable compound contained in the second region is greater than the total area of ​​the decomposable compound contained in the first region.

4. A light-emitting element according to any one of claims 1 to 3, wherein each of the first region and the second region has a smaller size of the first portion and the second portion in the cross section.

5. A light-emitting element comprising: a first electrode; a second electrode; a first functional material; and a first functional layer formed between the first electrode and the second electrode, the first functional layer being larger in planar view than a smaller of the first electrode and the second electrode; wherein the first functional layer comprises a first portion formed in a light-emitting region and a second portion formed in a non-light-emitting region; a first concentration is defined as the concentration of the first medium in a first unit portion having a predetermined volume included in the first portion; a second concentration is defined as the concentration of the first medium in a second unit portion having the predetermined volume included in the second portion; and the second portion includes the second unit portion having the second concentration higher than the first concentration.

6. The light-emitting element according to claim 5, wherein the first medium contains a polymer material, and the concentration of the polymer material contained in the second unit is higher than the concentration of the polymer material contained in the first unit.

7. The light-emitting element described in claim 5, wherein the first medium material contains a decomposable compound that is decomposed by the application of energy, and the concentration of the decomposable compound contained in the second unit is higher than the concentration of the decomposable compound contained in the first unit.

8. A light-emitting element according to any one of claims 5 to 7, wherein each of the first unit and the second unit has a volume that is smaller than the volume of the first portion and the volume of the second portion.

9. The light-emitting device according to any one of claims 1 to 8, wherein the first functional material is a plurality of particles.

10. The light-emitting device of claim 9, wherein each of the plurality of particles is a nanoparticle.

11. A light-emitting element as described in claim 9 or 10, wherein the average distance between the plurality of particles in the first portion of the first functional layer is shorter than the average distance between the plurality of particles in the second portion of the first functional layer.

12. A light-emitting element described in any one of claims 1 to 11, wherein the first functional layer includes a protrusion at the end of the second portion of the first functional layer, the protrusion having a thickness greater than that of the portion other than the end.

13. A light-emitting element according to any one of claims 1 to 12, wherein the electrical conductivity of the first portion of the first functional layer is higher than the electrical conductivity of the second portion of the first functional layer.

14. A light-emitting element described in any one of claims 1 to 13, comprising a second functional layer formed between the first electrode and the second electrode, the second functional layer being equal to or larger than the first portion of the first functional layer in a planar view.

15. A light-emitting element according to any one of claims 1 to 14, wherein the first functional layer is a light-emitting layer, the first functional material is quantum dots, and the first medium material includes at least one of a ligand, a dispersant, and a matrix.

16. The light-emitting element according to claim 14, wherein the first functional layer is a light-emitting layer, the first functional material is a quantum dot, the first medium material includes at least one of a ligand, a dispersant, and a matrix, and the second functional layer is a charge transport layer.

17. The light-emitting element according to claim 15 or 16, wherein the first medium material contains at least one of a halogen element and a halogen compound.

18. A light-emitting element according to any one of claims 15 to 17, wherein the electrical conductivity of the first medium material is lower than the electrical conductivity of the core of the quantum dot.

19. A light-emitting device according to any one of claims 15 to 18, wherein the electrical conductivity of the first medium material is lower than the electrical conductivity of the shell of the quantum dot.

20. A light-emitting element described in any one of claims 1 to 14, wherein the first functional layer is at least one of a hole transport layer and a hole injection layer, the first functional material is hole transport nanoparticles, and the first medium material includes a dispersion material for the hole transport nanoparticles.

21. The light-emitting element described in claim 14, wherein the first functional layer is a hole transport layer, the first functional material is hole transport nanoparticles, the first medium material includes a dispersion material of the hole transport nanoparticles, and the second functional layer is a hole injection layer.

22. A light-emitting element described in any one of claims 1 to 14, wherein the first functional layer is at least one of an electron transport layer and an electron injection layer, the first functional material is electron transport nanoparticles, and the first medium material includes a dispersion material for the electron transport nanoparticles.

23. The light-emitting element described in claim 14, wherein the first functional layer is an electron transport layer, the first functional material is electron transport nanoparticles, the first medium material includes a dispersion material of the electron transport nanoparticles, and the second functional layer is an electron injection layer.

24. A light-emitting element according to any one of claims 1 to 23, wherein the first medium material of the first portion and the first medium material of the second portion are at least partially different from each other.

25. A light-emitting element described in any one of claims 14, 16, 21, and 23, comprising a bank including a portion formed thicker than the film thickness of the smaller of the first electrode and the second electrode, and the film thickness of the second functional layer formed on the bank is thinner than the film thickness of the second functional layer formed other than on the bank.

26. A light-emitting element described in any one of claims 1 to 25, comprising a bank including a portion formed thicker than the film thickness of the smaller of the first electrode and the second electrode, and the film thickness of the end of the first functional layer formed on the bank is thicker than the film thickness of the portion of the first functional layer formed on the bank other than the end.

27. The light-emitting element according to claim 25 or 26, wherein the bank is formed in an uneven shape, and the end of the first functional layer is located on a concave portion or a side surface of a convex portion of the uneven shape.

28. A light-emitting element described in any one of claims 25 to 27, comprising: the bank; a light-reflecting layer located above the bank; and the first functional layer located above the light-reflecting layer.

29. A light-emitting element described in any one of claims 1 to 28, having an electrical conductivity lower than that of the second portion of the first functional layer, and at least an insertion layer overlapping the first functional layer in a planar view is provided between the first electrode and the second electrode.

30. A display device comprising a plurality of the light-emitting elements according to any one of claims 1 to 29.

31. A display device as described in claim 30, wherein some of the plurality of light-emitting elements are first light-emitting elements, and another portion of the plurality of light-emitting elements are second light-emitting elements, the first light-emitting elements have the first functional layer, and the second light-emitting elements have a third functional layer containing a second functional material and a second medium material as the first functional layer having the first portion and the second portion, and the second portion of the first functional layer and the second portion of the third functional layer are stacked.

32. A method for forming a functional layer, comprising: a first step of forming a first functional layer using a mixed solution containing a first functional material and a first medium material; and a second step of making the amount of the first medium material contained in a first portion of the first functional layer less than the amount of the first medium material contained in a second portion of the first functional layer.

33. The method for forming a functional layer according to claim 32, wherein the first functional material is a plurality of particles.

34. The method for forming a functional layer according to claim 33, wherein each of the plurality of particles is a nanoparticle.

35. A method for forming a functional layer according to any one of claims 32 to 34, including, before the first step, a step of forming a resist film so that the region where the first functional layer is to be formed becomes an opening portion; in the first step, the first functional layer is formed so that the film thickness of the first functional layer formed at the edge of the opening portion of the resist film is thicker than the film thickness of the first functional layer formed in the center of the opening portion; and in the second step, the first functional layer formed at the edge of the opening portion becomes the second portion of the first functional layer, and the first functional layer formed in the center of the opening portion becomes the first portion of the first functional layer.

36. A method for forming a functional layer described in any one of claims 32 to 34, comprising a step of forming a resist film on at least a portion of the second portion of the first functional layer after the first step and before the second step.

37. A method for forming a functional layer according to claim 35 or 36, wherein the second step includes a first cleaning step of the first functional layer using a stripping solvent for the resist film and a stripping step of the resist film.

38. A method for forming a functional layer as described in claim 37, wherein the second step includes a second cleaning step of the first functional layer using a cleaning solvent, which is performed after a first cleaning step of the first functional layer and a stripping step of the resist film.

39. A method for forming a functional layer described in claim 37 or 38, wherein the first medium material contains a cross-linkable polymer material, and after the second step, the cross-linkable polymer material contained in the second portion of the first functional layer is cross-linked to a greater extent than the cross-linkable polymer material contained in the first portion of the first functional layer.

40. A method for forming a functional layer as described in claim 32, wherein the first medium material includes a cross-linkable polymer material, the first step cross-links the cross-linkable polymer material contained in the second portion of the first functional layer to a greater extent than the cross-linkable polymer material contained in the first portion of the first functional layer, and the second step washes the first functional layer with a solvent.

41. A method for forming a functional layer as described in claim 32, wherein the first medium material contains a decomposable compound that is decomposed by the application of energy, and in the second step, by applying energy, the decomposable compound contained in the first portion of the first functional layer is decomposed and removed in greater amounts than the decomposable compound contained in the second portion of the first functional layer.

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