Light emitting element, display device, and light emitting element manufacturing method

Abstract

A red-light-emitting element (10R) includes: an anode (2); a cathode (8); a red functional layer (7R) including a red-light-emitting layer (5R) and electron transport layers (6a,6b); a light-emitting region (RHR) in which the red functional layer (7R) is in contact with both the anode (2) and the cathode (8); and a non-light-emitting region (RNHR) that is a region other than the light-emitting region (RHR). At least two layers of the red functional layer (7R) that includes at least the electron transport layers (6a, 6b) are formed so as to extend from the light-emitting region (RHR) to the non-light-emitting region (RNHR). The electron transport layer (6a) of the light-emitting region (RHR) includes a section in which the concentration of one element, per unit volume, is higher than at least a portion of the electron transport layers (6a, 6b) of the non-light-emitting region (RNHR).

Description

Light-emitting element, display device, and method for manufacturing the same

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

[0002] In recent years, various display devices equipped with light-emitting elements have been developed, and in particular, display devices equipped with QLEDs (Quantum dot Light Emitting Diodes) or OLEDs (Organic 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 Document 1 describes that in each pixel of an organic EL display panel having an organic EL layer including a flat portion and a thin-film portion that is thinner than the flat portion, a current larger than that flowing through the thin-film portion is suppressed from flowing through the flat portion, thereby suppressing deterioration in each pixel caused by the thin-film portion.

[0004] WO2013 / 011599 A1

[0005] Patent Document 1 describes increasing the electrical resistivity by deteriorating the thin-film portion of the organic EL layer by irradiating it with UV light or laser light. Patent Document 1 also describes increasing the electrical resistivity by irradiating a portion of the layer responsible for electron injection and the layer responsible for hole injection, which are provided between the first organic light-emitting layer and the second organic light-emitting layer, with light to form a mixed layer.

[0006] However, as described in Patent Document 1, the method of degrading a portion of a film by irradiating it with UV light or laser light may encounter the following problems. To avoid irradiating unintended areas with UV light or laser light, high-precision alignment adjustment is required, and the size of the light irradiation spot must also be reduced. However, the more precise the alignment adjustment and the smaller the size of the light irradiation spot, the greater the degradation in productivity. Furthermore, in the method of degrading a portion of a film by irradiating it with UV light or laser light, excessive light irradiation can cause excessive film degradation, resulting in reliability issues. Insufficient light irradiation prevents the desired level of degradation, resulting in a narrow process margin in the light irradiation process. Furthermore, films formed by the method of degrading a portion of a film by irradiating it with UV light or laser light have boundaries between the irradiated and unirradiated portions, which are prone to unevenness due to light leakage and other factors, potentially resulting in degradation of the light-emitting characteristics of light-emitting elements and degradation of the display quality of display devices. Furthermore, when a material with low mobility or conductivity is used as the light-emitting layer, the layer responsible for electron injection, or the layer responsible for hole injection, even if a part of the layer is irradiated with UV light or laser light to cause deterioration, it is difficult to obtain a difference in characteristics due to deterioration between the irradiated part and the non-irradiated part.

[0007] One aspect of the present disclosure aims to provide a light-emitting element, a display device, and a method for manufacturing a light-emitting element that improves the luminous efficiency in the light-emitting region without changing the charge transport properties due to deterioration caused by light irradiation of a part of the charge transport layer.

[0008] In order to solve the above-mentioned problems, the light-emitting element of the present disclosure includes an anode, a cathode, a light-emitting layer provided between the anode and the cathode, and a charge transport layer containing a charge transport material provided between the light-emitting layer and one of the anode and the cathode, a functional layer provided between the anode and the cathode, a light-emitting region where the functional layer is in contact with both the anode and the cathode, and a non-light-emitting region which is a region other than the light-emitting region, wherein at least two or more of the functional layers including at least the charge transport layer are formed spanning from the light-emitting region to the non-light-emitting region, and the charge transport layer in the light-emitting region includes a portion where the concentration of a certain element per unit volume is higher than at least a portion of the charge transport layer in the non-light-emitting region.

[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 manufacturing a light-emitting element of the present disclosure includes: a first step of forming one of an anode and a cathode; a second step of forming functional layers including a charge transport layer formation step of forming a charge transport layer containing a charge transport material and an emissive layer formation step of forming an emissive layer; and a third step of forming the other of the anode and the cathode, wherein the second step forms two or more layers of the functional layers including at least the charge transport layer across a luminescent region, which is a region where the functional layer contacts both the anode and the cathode, and a non-luminescent region, which is a region other than the luminescent region, and includes, after the charge transport layer formation step, an addition step of adding the certain element so that the charge transport layer in the luminescent region includes a portion having a higher concentration per unit volume of the certain element than at least a portion of the charge transport layer in the non-luminescent region.

[0011] According to one aspect of the present disclosure, it is possible to provide a light-emitting element, a display device, and a method for manufacturing a light-emitting element in which the light-emitting efficiency in the light-emitting region is improved without changing the charge transport characteristics due to deterioration caused by light irradiation of part of the charge transport layer.

[0012] 6 is a plan view showing a schematic configuration of a display device of embodiment 1; FIG. 7 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display region of the display device of embodiment 1; FIG. 8 is a view showing an example of a method for manufacturing the red light-emitting element shown in FIG. 2; FIG. 9 is a view showing another example of a method for manufacturing the red light-emitting element shown in FIG. 2; FIG. 10 is a view showing yet another example of a method for manufacturing the red light-emitting element shown in FIG. 11; FIG. 11 is a view showing yet another example of a method for manufacturing the red light-emitting element shown in FIG. 12; FIG. 12 is a view showing yet another example of a method for manufacturing the red light-emitting element shown in FIG. 13; FIG. 13 is a view showing an example of a method for forming a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer in the method for manufacturing the red light-emitting element shown in FIG. 14; FIG. 15 is a cross-sectional view showing a schematic configuration of an example of a red light-emitting element and a green light-emitting element that can be provided in the display region of the display device of embodiment 1; FIG. 16 is a cross-sectional view showing a schematic configuration of another example of a red light-emitting element and a green light-emitting element that can be provided in the display region of the display device of embodiment 1; 1 is a diagram showing the conduction band lower edge (CBM) of the quantum dots included in the red light-emitting layer, the conduction band lower edge (CBM) of the quantum dots included in the green light-emitting layer, the conduction band lower edge (CBM) of the quantum dots included in the blue light-emitting layer, and the conduction band lower edge (CBM) of the electron transport layer that changes depending on the concentration of halogen elements. 2 is a diagram showing the conduction band lower edge (CBM) of the quantum dots included in the red light-emitting layer, the conduction band lower edge (CBM) of the quantum dots included in the green light-emitting layer, the conduction band lower edge (CBM) of the quantum dots included in the blue light-emitting layer, and the conduction band lower edge (CBM) of the electron transport layer that changes depending on the concentration of sulfur elements. 3 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display region of a display device of embodiment 2. 4 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display region of a display device that is a comparative example.

[0013] The following describes embodiments of the present disclosure with reference to Figures 1 to 14. 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 display units PIX, each of which includes a red pixel RSP, a green pixel GSP, and a blue pixel BSP. In this embodiment, a case where one display unit PIX is configured with a red pixel RSP, a green pixel GSP, and a blue pixel BSP will be described as an example, but this is not limiting. For example, one display unit PIX may include pixels of other colors in addition to the red pixel RSP, the green pixel GSP, and the blue pixel BSP.

[0016] Fig. 2 is a cross-sectional view showing a schematic configuration of a red light-emitting element 10R provided in a red pixel RSP in the display area DA of the display device 1 of Embodiment 1. Note that Fig. 2 shows only a part of the light-emitting region RHR and the non-light-emitting region RNHR located to the left of the light-emitting region RHR, but the non-light-emitting region RNHR and the bank 3 are formed to surround the light-emitting region RHR.

[0017] 2 includes an anode 2, a cathode 8, a red functional layer 7R provided between the anode 2 and the cathode 8, a light-emitting region RHR where the red functional layer 7R is in contact with both the anode 2 and the cathode 8, and a non-light-emitting region RNHR where the red functional layer 7R is in contact with the anode 2 and the cathode 8. In this embodiment, the red light-emitting element 10R includes a bank 3 that covers the end of the anode 2, and the bank 3 forms a non-light-emitting region RNHR where the red functional layer 7R is not in contact with the anode 2. Therefore, in this embodiment, the region where the bank 3 is formed is the non-light-emitting region RNHR. As described above, the non-light-emitting region RNHR refers to a region where the red functional layer 7R is not in contact with the anode 2 or a region where the bank 3 is formed, and does not refer to a region where no light is emitted at all. In the non-light-emitting region RNHR, light may be emitted that is weaker than that in the light-emitting region RHR. In this embodiment, the red light-emitting element 10R is described using an example in which it includes a bank 3 covering the end of the anode 2, but is not limited thereto and may not include the bank 3. The red functional layer 7R includes a red light-emitting layer 5R provided between the anode 2 and the cathode 8, and electron transport layers 6a and 6b containing an electron transport material which is a charge transport material and provided between the red light-emitting layer 5R and the cathode 8. In this embodiment, the red functional layer 7R is described using an example in which it includes a hole transport layer 4 containing a hole transport material which is a charge transport material, the red light-emitting layer 5R, and electron transport layers 6a and 6b containing an electron transport material, but is not limited thereto and may, for example, include the red light-emitting layer 5R and electron transport layers 6a and 6b containing an electron transport material.

[0018] As shown in FIG. 2 , two or more layers of the red functional layer 7R including at least the electron transport layers 6 a and 6 b, in this embodiment, three layers, namely, the hole transport layer 4 including a hole transport material, the red light-emitting layer 5R, and the electron transport layers 6 a and 6 b, are formed across the light-emitting region RHR and the non-light-emitting region RNHR. However, this is not limited to this, and two layers, namely, the red light-emitting layer 5R and the electron transport layers 6 a and 6 b, may be formed across the light-emitting region RHR and the non-light-emitting region RNHR, or two layers, namely, the hole transport layer 4 including a hole transport material and the electron transport layers 6 a and 6 b, may be formed across the light-emitting region RHR and the non-light-emitting region RNHR.

[0019] As shown in FIG. 2 , in this embodiment, a case will be described as an example in which the electron transport layer 6 a in the light-emitting region RHR has a higher concentration per unit volume of a certain element that fulfills the function of filling element vacancies (oxygen vacancies) that can become a source of electron scattering in the electron transport material than the electron transport layer 6 b out of the electron transport layers 6 a and 6 b formed in the non-light-emitting region RNHR. However, the present invention is not limited to this, and it is sufficient that the electron transport layer in the light-emitting region RHR includes a portion in which the concentration per unit volume of a certain element is higher than that of at least a part of the charge transport layer in the non-light-emitting region RNHR. For example, a portion of the electron transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than a portion of the electron transport layer in the non-light-emitting region RNHR, a portion of the electron transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than the electron transport layer in the non-light-emitting region RNHR, the electron transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than a portion of the electron transport layer in the non-light-emitting region RNHR, or the electron transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than the electron transport layer in the non-light-emitting region RNHR. The concentration of the certain element per unit volume in the electron transport layer in the light-emitting region RHR or the non-light-emitting region RNHR can be calculated by (the number of the certain element contained in the corresponding electron transport layer) / (the volume of the corresponding electron transport layer). The one element is not particularly limited, but when the electron transport material contains, for example, oxygen element, as in the present embodiment, it may be an element that can fill oxygen vacancies that occur in the electron transport material. As an element that can fill oxygen vacancies, for example, Group 16 elements and Group 17 elements can be suitably used, and it is preferable to use at least one of a halogen element and a sulfur element. As long as it can fill oxygen vacancies that occur in the electron transport material, the one element may be an element different from one or more elements that constitute the electron transport material.

[0020] In this embodiment, the case where electron transport layers 6a and 6b are provided as charge transport layers between the red light-emitting layer 5R and the cathode 8 will be described as an example, but the present invention is not limited to this. The charge transport layer provided between the red light-emitting layer 5R and the cathode 8 may be an electron injection layer, or may be an electron transport layer and an electron injection layer.

[0021] The electron transport layer 6b shown in FIG. 2 , which includes an electron transport material that does not contain the certain element that functions to fill oxygen vacancies in the electron transport material, is a conventional electron transport layer and includes an electron scattering source that causes high resistance. The electron transport material may be an inorganic material. When the electron transport material is a metal oxide or metal oxide particles containing at least one of Zn, Mg, Ti, Si, Sn, W, Ta, Ba, Zr, Al, Y, and Hf, it includes oxygen vacancies that are electron scattering sources that cause high resistance. In this embodiment, zinc oxide nanoparticles are used as the electron transport material, but this is not limited thereto. Here, the case where zinc oxide nanoparticles containing oxygen element are used as the electron transport material and the electron scattering source is oxygen vacancies is described as an example, but this is not limited thereto. The electron transport material is not particularly limited as long as it includes element vacancies that can serve as electron scattering sources.

[0022] As shown in FIG. 2 , the electron transport layer 6 a in the light-emitting region RHR contains a halogen element as the certain element that fills oxygen vacancies that occur in the electron transport material. The halogen element is an element different from one or more elements (in this embodiment, Zn and O) that constitute the electron transport material. The halogen element fills oxygen vacancies, which are electron scattering sources that cause high resistance, thereby reducing the effects of electron scattering and achieving low resistance in the electron transport layer 6 a in the light-emitting region RHR. In the red light-emitting element 10R shown in FIG. 2 , the light-emitting efficiency in the light-emitting region PHR can be improved. The electron transport layer 6 b containing the electron transport material shown in FIG. 2 , which does not contain the certain element that fills oxygen vacancies that occur in the electron transport material, is a conventional electron transport layer and has not been subjected to any particular resistance-increasing treatment. However, the low resistance of the electron transport layer 6 a in the light-emitting region RHR can suppress leakage current flowing through the electron transport layer 6 b.

[0023] FIG. 14 is a cross-sectional view showing a schematic configuration of a red light emitting element 30R provided in the display area of ​​a display device as a comparative example.

[0024] As shown in FIG. 14 , the red light-emitting element 30R includes only the electron transport layer 6 b containing an electron transport material that does not contain the certain element that functions to fill oxygen vacancies that occur in the electron transport material, in both the light-emitting region RHR and the non-light-emitting region RNHR. This results in a large leakage current in the non-light-emitting region RNHR, and a decrease in luminous efficiency in the light-emitting region RHR.

[0025] Although not shown, when comparing the current densities at the same voltage between an EOD (Electron Only Device) including an electron transport layer 6 b containing the electron transport material shown in Figure 14 that does not contain the certain element that functions to fill oxygen vacancies generated in the electron transport material and an EOD including an electron transport layer 6 a containing Cl, a halogen element, as the certain element, the EOD including the electron transport layer 6 a containing Cl, a halogen element, as the certain element can achieve a higher current density at a lower voltage, and it was confirmed that the inclusion of Cl, a halogen element, can reduce the resistance of the electron transport layer 6 a. Note that a similar effect can be obtained with an EOD including an electron transport layer 6 a containing sulfur element or a halogen element and sulfur element as the certain element.

[0026] 2 , when the end of the non-emissive region RNHR closer to the light-emitting region RHR is designated as a first end RNHRE1, the end of the non-emissive region RNHR farther from the light-emitting region RHR is designated as a second end RNHRE2, and the region of the non-emissive region RNHR closer to the second end RNHRE2 than to the first end RNHRE1 is designated as a first region RNHR1, at least a portion of the electron transport layer of the light-emitting region RHR, in this embodiment, the entire electron transport layer 6 a of the light-emitting region RHR, has a higher concentration per unit volume of the certain element than the electron transport layer 6 b of the first region RNHR1. The concentration per unit volume of the certain element may be confirmed using, for example, a transmission electron microscope (TEM) and energy dispersive X-ray spectroscopy (EDX), time-of-flight ion-imaging (TOF-SIMS), or X-ray photoelectron spectroscopy (XPS).

[0027] 2 , in this embodiment, the electron transport layer 6 a containing the certain element is provided not only in the light-emitting region RHR but also in a portion of the second region RNHR2 closer to the light-emitting region RHR, which is a region in the non-light-emitting region RNHR that is closer to the first end RNHRE1 of the non-light-emitting region RNHR than to the second end RNHRE2 of the non-light-emitting region RNHR. However, this is not limited to this. For example, although not shown, of the electron transport layers in the light-emitting region RHR and the non-light-emitting region RNHR, only the electron transport layer in the light-emitting region RHR may contain the certain element. That is, the light-emitting region RHR may be provided with an electron transport layer 6 a containing the certain element, and the non-light-emitting region RNHR may be provided with an electron transport layer 6 b that does not contain the certain element.

[0028] Furthermore, the electron transport layer of the light-emitting region RHR and the electron transport layer of the non-light-emitting region RNHR may each contain the certain element, the electron transport layer of the light-emitting region RHR may have a higher concentration of the certain element per unit volume than the electron transport layer of the non-light-emitting region RNHR, and the concentration of the certain element per unit volume of the electron transport layer of the second region RNHR2 of the non-light-emitting region RNHR may be equal to or greater than the concentration of the certain element per unit volume of the electron transport layer of the first region RNHR1 of the non-light-emitting region RNHR.

[0029] 2 , in this embodiment, the light-emitting region RHR is provided with an electron transport layer 6 a doped with the certain element, and at least a portion of the non-light-emitting region RNHR is provided with an electron transport layer 6 b that does not contain the certain element. As described above, the certain element, a halogen element, fills oxygen vacancies that are electron scattering sources that increase resistance, thereby reducing the influence of electron scattering and achieving low resistance of the electron transport layer 6 a in the light-emitting region RHR. Because the non-light-emitting region RNHR includes the electron transport layer 6 b that does not contain the certain element, the electrical conductivity of the electron transport layer in the non-light-emitting region RNHR is lower than the electrical conductivity of the electron transport layer 6 a in the light-emitting region RHR.

[0030] 2 , the non-light-emitting region RNHR of the red light-emitting element 10R is provided with a bank 3, and two or more layers of the red functional layer 7R including at least the electron transport layers 6a and 6b provided in the non-light-emitting region RNHR (in this embodiment, three layers: the hole transport layer 4 containing a hole transport material, the red light-emitting layer 5R, and the electron transport layers 6a and 6b) are separated from the anode 2 via the bank 3. The electron transport layers 6a and 6b are formed across the light-emitting region RHR and on the bank 3 provided in the non-light-emitting region RNHR, and the electrical conductivity of the electron transport layer 6b formed on the bank 3 is lower than the electrical conductivity of the electron transport layer 6a in the light-emitting region RHR. As shown in FIG. 2 , the bank 3 includes an inclined surface formed at a forward taper angle, and the electron transport layers 6 a and 6 b are formed across the bank 3 provided in the light-emitting region RHR and the non-light-emitting region RNHR. The electron transport layer 6 b formed on the inclined surface of the bank 3 has a lower electrical conductivity than the electron transport layer 6 a in the light-emitting region RHR.

[0031] In this embodiment, the case where the red light-emitting element 10R shown in FIG. 2 is a QLED (Quantum dot Light Emitting Diode) will be described as an example, and the red light-emitting layer 5R provided in the red light-emitting element 10R is a light-emitting layer containing quantum dots. However, if the red light-emitting element 10R shown in FIG. 2 is an OLED (Organic Light Emitting Diode), the red light-emitting layer 5R is a light-emitting layer containing an organic light-emitting material.

[0032] Although the red light-emitting element 10R has been described as an example here, the present invention is not limited to this, and similarly to the red light-emitting element 10R, the green light-emitting element and the blue light-emitting element can also incorporate the electron transport layer 6a containing the above-mentioned one element that functions to fill oxygen vacancies that occur in the electron transport material.

[0033] A method for manufacturing the red light emitting element 10R will be described below with reference to FIGS.

[0034] 3A to 3C are diagrams showing an example of a method for manufacturing the red light emitting element 10R shown in FIG.

[0035] The step S1 shown in FIG. 3 includes a first step of forming an anode 2 and a second step of forming a red functional layer 7R, which includes a light-emitting layer forming step of forming a red light-emitting layer 5R and an electron transport layer forming step of forming an electron transport layer 6b containing an electron transport material. In the second step described above, two or more layers of the red functional layer 7R, including at least the electron transport layer 6b, are formed across the light-emitting region RHR and the non-light-emitting region RNHR. In this embodiment, three layers are formed: a hole transport layer 4 containing a hole transport material, the red light-emitting layer 5R, and the electron transport layer 6b. The steps S2 and S3 shown in FIG. 3 include, after the electron transport layer forming step, an addition step of adding a certain element so that the electron transport layer 6a in the light-emitting region RHR includes a portion having a higher concentration per unit volume of the certain element than at least a portion of the electron transport layer 6b in the non-light-emitting region RNHR. Although not shown, the third step of forming a cathode 8 is further included after the step S3 shown in FIG. 3.

[0036] 3, i.e., in the steps of adding the certain element, a resist film RM formed in a predetermined pattern is used to add the certain element to regions of the electron transport layer 6b corresponding to portions where the resist film RM is not formed. In the step of adding the certain element to the electron transport layer 6b, for example, a treatment solution ES containing the certain element may be applied onto the electron transport layer 6b. The treatment solution ES containing a halogen element as the certain element includes a halogen medium and a solvent. The halogen medium may be, for example, a halide or a halide salt (e.g., ZnCl ２ , ZnF ２ , ZnBr ２ and ZnI ２) can be suitably used, and as the solvent, for example, water, an alcohol-based solvent, an ether-based solvent, or a mixture of these solvents can be suitably used. Furthermore, the treatment solution ES containing sulfur as the certain element contains a sulfur medium and a solvent, and as the sulfur medium, for example, a sulfide (e.g., an alkali metal salt) can be suitably used, and as the solvent, for example, water, an alcohol-based solvent, an ether-based solvent, or a mixture of these solvents can be suitably used. Without being limited thereto, a treatment solution ES containing a halogen element and sulfur element as the certain element may also be used. Furthermore, the certain element may be an element different from one or more elements constituting the charge transport material.

[0037] As shown in FIG. 2 , the end of the non-light-emitting region RNHR closer to the light-emitting region RHR is designated as the first end RNHRE1, the end of the non-light-emitting region RNHR farther from the light-emitting region RHR is designated as the second end RNHRE2, and the region in the non-light-emitting region RNHR that is closer to the second end RNHRE2 than to the first end RNHRE1 is designated as the first region RNHR1. In the step of adding the certain element to the electron transport layer 6 b shown in FIG. 3 , the concentration of the certain element per unit volume is set to be higher in at least a part of the electron transport layer in the light-emitting region RHR, in this embodiment, the entire electron transport layer 6 a in the light-emitting region RHR, than in the electron transport layer 6 b in the first region RNHR1. In the present embodiment, the case where the certain element is not added to the electron transport layer 6 b provided in the non-light-emitting region RNHR has been described as an example, but the present invention is not limited to this. As long as the concentration per unit volume of the certain element in the electron transport layer provided in the non-light-emitting region RNHR is lower than the concentration per unit volume of the certain element in the electron transport layer provided in the light-emitting region RHR, the certain element may also be added to the electron transport layer provided in the non-light-emitting region RNHR.

[0038] FIG. 4 is a diagram showing another example of a method for manufacturing the red light emitting element 10R shown in FIG.

[0039] Step S11 shown in FIG. 4 is the same as step S1 shown in FIG. 3 described above, and therefore its description will be omitted here. Steps S12 and S13 shown in FIG. 4 are steps of adding the certain element (a halogen element in this embodiment) to the electron transport layer 6a in the light-emitting region RHR after the electron transport layer formation step. Although not shown, a step of forming a cathode 8 is further included after step S13 shown in FIG. 4. In the adding step, a mask M having an opening is used to add the certain element to the region of the electron transport layer 6b corresponding to the opening in the mask M. In the adding step, the certain element can be added to the electron transport layer 6b using the mask M having an opening by a method such as vapor deposition, sputtering, misting, or spraying. When using the misting method or spraying method, the above-described treatment solution ES containing the certain element can be suitably used. When using the vapor deposition method, a chlorothiazole-based organic material or a halogenated benzene-based organic material may be used as a halogen source, for example, a Cl source, and BiCl may be used. ３ , CoCl ２ , InCl ２ , NiCl ２ Alternatively, an inorganic material such as ZnS may be used. Furthermore, a thiophene-based organic material or a thiazole-based organic material may be used as the sulfur source, or an inorganic material such as ZnS may be used. When a sputtering method is used, an ion sputtering material such as MoS may be used. For example, when MoS is added to the electron transport layer 6b using a sputtering method, Mo is also added and may remain as a residue in the electron transport layer 6b.

[0040] FIG. 5 is a diagram showing yet another example of a method for manufacturing the red light emitting element 10R shown in FIG.

[0041] In step S21 shown in FIG. 5 , in the light-emitting layer forming step of forming the red light-emitting layer 5R′, which is performed before the electron-transporting layer forming step of forming the electron-transporting layer 6b, the red light-emitting layer 5R′ containing the certain element (in this embodiment, Cl, which is a halogen element) is formed.

[0042] 5, the certain element contained in the red light-emitting layer 5R′ partially migrates to the electron transport layer 6b, thereby forming the electron transport layer 6a containing the certain element. The electron transport layer 6a in this state can also achieve low resistance of the electron transport layer 6a.

[0043] As shown in step S23 in FIG. 5 , in the addition step performed after the step of forming the cathode 8, a voltage is applied to the light-emitting region RHR via each of the anode 2 and the cathode 8, thereby moving the certain element contained in the red light-emitting layer 5R′ in the light-emitting region RHR to the electron transport layer 6 b in the light-emitting region RHR, thereby forming the electron transport layer 6 a containing the certain element.

[0044] Fig. 6 is a diagram showing yet another example of the method for manufacturing the red light emitting element 10R shown in Fig. 2. Fig. 7 is a diagram showing an example of a method for forming the red light emitting layer 5R, the green light emitting layer 5G, and the blue light emitting layer 5B in the method for manufacturing the red light emitting element 10R shown in Fig. 6.

[0045] 6 , the non-light-emitting region RNHR of the red light-emitting element 10R includes the red light-emitting layer 5R provided in the red light-emitting element 10R, the green light-emitting layer 5G provided in the green light-emitting element 10G, and the blue light-emitting layer 5B provided in the blue light-emitting element 10B, and the non-light-emitting region RNHR of the red light-emitting element 10R includes a laminated portion in which the red light-emitting layer 5R, the green light-emitting layer 5G, and the blue light-emitting layer 5B are laminated. As shown in FIG. 7 , by forming the red light-emitting layer 5R, the green light-emitting layer 5G, and the blue light-emitting layer 5B, laminated portions in which the red light-emitting layer 5R, the green light-emitting layer 5G, and the blue light-emitting layer 5B are laminated can be formed in the non-light-emitting region RNHR of the red light-emitting element 10R, the non-light-emitting region GNHR of the green light-emitting element 10G, and the non-light-emitting region BNHR of the blue light-emitting element 10B, respectively. Without being limited thereto, the non-light-emitting region RNHR of the red light-emitting element 10R may include a laminated portion in which two adjacent light-emitting elements, that is, the red light-emitting layer 5R provided in the red light-emitting element 10R and the green light-emitting layer 5G provided in the green light-emitting element 10G, are laminated, or a laminated portion in which the red light-emitting layer 5R provided in the red light-emitting element 10R and the blue light-emitting layer 5B provided in the blue light-emitting element 10B are laminated. In this way, by providing a laminated portion of the light-emitting layers in the non-light-emitting region RNHR, it is possible to further suppress leakage current in the non-light-emitting region RNHR.

[0046] 2 has a top-emission forward stack structure as an example, but the present invention is not limited thereto and may have a top-emission inverted stack structure, a bottom-emission forward stack structure, or a bottom-emission inverted stack structure. Since the red light-emitting element 10R has a forward stack structure in which the cathode 8 is disposed above the anode 2, to form the red light-emitting element 10R as a top-emission element, the anode 2 may be formed from an electrode material that reflects visible light, and the cathode 8 may be formed from an electrode material that transmits visible light. To form the red light-emitting element 10R as a bottom-emission element, the anode 2 may be formed from an electrode material that transmits visible light, and the cathode 8 may be formed from an electrode material that reflects visible light. On the other hand, in the case of an inverted stack structure in which the anode 2 is disposed as an upper layer than the cathode 8, in order to form a top emission type, the cathode 8 may be formed from an electrode material that reflects visible light, and the anode 2 may be formed from an electrode material that transmits visible light, whereas in order to form a bottom emission type, the cathode 8 may be formed from an electrode material that transmits visible light, and the anode 2 may be formed from an electrode material that reflects visible light.

[0047] The electrode material that reflects visible light is not particularly limited as long as it can reflect visible light and has electrical conductivity. Examples of the electrode material that reflects visible light include metal materials such as Al, Mg, Li, and Ag, alloys of the metal materials, laminates of the metal materials and transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), and laminates of the alloys and the transparent metal oxides.

[0048] On the other hand, the electrode material that transmits visible light is not particularly limited as long as it can transmit visible light and has conductivity, and examples thereof include transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), thin films made of metal materials such as Al and Ag, and nanowires made of metal materials such as Al and Ag.

[0049] As the electron transport material contained in the electron transport layers 6 a and 6 b, for example, inorganic materials such as metal oxides such as oxides containing Zn and Mg or zinc oxide, or nanoparticles of these metal oxides can be suitably used; however, organic materials may also be used as long as they cause element deficiencies that can become electron scattering sources.

[0050] The bank 3 can be formed, for example, by applying an organic material such as polyimide or acrylic and then patterning it using a photolithography method. In this embodiment, the bank 3 is patterned so that each of the opposing side surfaces has an inclined surface with a forward taper angle.

[0051] FIG. 8 is a cross-sectional view showing a schematic configuration of an example of a red light emitting element 10R and a green light emitting element 10G that can be provided in the display area DA of the display device 1 of the first embodiment.

[0052] The display device 1 shown in FIG. 8 includes a red light emitting element 10R, a green light emitting element 10G, and a blue light emitting element 10B, but FIG. 8 shows only the red light emitting element 10R and the green light emitting element 10G.

[0053] 8, the electron transport layers 6a, 6b, and 6c are provided as a single continuous film for the red light-emitting element 10R, the green light-emitting element 10G, and the blue light-emitting element 10B, respectively. That is, the electron transport layers 6a, 6b, and 6c are a common electron transport layer (common charge transport layer).

[0054] FIG. 11 shows the conduction band minimum (CBM) of the quantum dots contained in the red light-emitting layer 5R, the conduction band minimum (CBM) of the quantum dots contained in the green light-emitting layer 5G, the conduction band minimum (CBM) of the quantum dots contained in the blue light-emitting layer 5B, and the conduction band minimum (CBM) of the electron transport layers 6a, 6c, and 6d, which changes depending on the concentration of the halogen element.

[0055] As shown in FIG. 11, in the electron transport layers 6a, 6c, and 6d, the conduction band minimum (CBM) becomes deeper as the concentration of the halogen element increases, and the conduction band minimum (CBM) becomes shallower as the concentration of the halogen element decreases.

[0056] FIG. 12 shows the conduction band minimum (CBM) of the quantum dots contained in the red light-emitting layer 5R, the conduction band minimum (CBM) of the quantum dots contained in the green light-emitting layer 5G, the conduction band minimum (CBM) of the quantum dots contained in the blue light-emitting layer 5B, and the conduction band minimum (CBM) of the electron transport layers 6a, 6c, and 6d, which changes depending on the concentration of sulfur element.

[0057] As shown in FIG. 12, in the electron transport layers 6a, 6c, and 6d, the conduction band minimum (CBM) becomes deeper as the concentration of sulfur element increases, and the conduction band minimum (CBM) becomes shallower as the concentration of sulfur element decreases.

[0058] In the common electron transport layer provided as a single continuous film for each of the red light-emitting element 10R, the green light-emitting element 10G, and the blue light-emitting element 10B, the common electron transport layer in the light-emitting region of the light-emitting element having the light-emitting layer with the shorter emission peak wavelength preferably has a lower concentration per unit volume of the halogen element than the common electron transport layer in the light-emitting region of the light-emitting element having the light-emitting layer with the longer emission peak wavelength. Hereinafter, a case will be described in which the light-emitting element having the light-emitting layer with the shorter emission peak wavelength is the green light-emitting element 10G, and the light-emitting element having the light-emitting layer with the longer emission peak wavelength is the red light-emitting element 10R. However, this is not limited thereto. The light-emitting element having the light-emitting layer with the shorter emission peak wavelength may be the blue light-emitting element 10B, and the light-emitting element having the light-emitting layer with the longer emission peak wavelength may be the red light-emitting element 10R. Alternatively, the light-emitting element having the light-emitting layer with the shorter emission peak wavelength may be the blue light-emitting element 10B, and the light-emitting element having the light-emitting layer with the longer emission peak wavelength may be the green light-emitting element 10G. As shown in Fig. 8, the green light-emitting element 10G includes a green light-emitting layer 5G having a shorter emission peak wavelength than the emission peak wavelength of the red light-emitting layer 5R included in the red light-emitting element 10R. The electron transport layer 6c in the emission region GHR of the green light-emitting element 10G preferably has a lower concentration per unit volume of the halogen element, which is the certain element, than the electron transport layer 6a in the emission region RHR of the red light-emitting element 10R. This configuration reduces the difference between the conduction band minimum (CBM) of the quantum dots included in the green light-emitting layer 5G and the conduction band minimum (CBM) of the electron transport layer 6c, as shown in Fig. 11, and also reduces the difference between the conduction band minimum (CBM) of the quantum dots included in the red light-emitting layer 5R and the conduction band minimum (CBM) of the electron transport layer 6a, thereby reducing the electron injection barrier in each of the green light-emitting element 10G and the red light-emitting element 10R.The electron transport layer 6 a in the light-emitting region RHR of the red light-emitting element 10R has a higher concentration per unit volume of halogen, which is one of the elements that functions to fill oxygen vacancies that occur in the electron transport material, than the electron transport layer 6 c in the light-emitting region GHR of the green light-emitting element 10G. Therefore, the electrical conductivity of the electron transport layer 6 a in the light-emitting region RHR of the red light-emitting element 10R is higher than the electrical conductivity of the electron transport layer 6 c in the light-emitting region GHR of the green light-emitting element 10G.

[0059] In the common electron transport layer provided as a single continuous film for each of the red light-emitting element 10R, the green light-emitting element 10G, and the blue light-emitting element 10B, the common electron transport layer in the light-emitting region of the light-emitting element having the light-emitting layer with the shorter emission peak wavelength preferably has a lower concentration per unit volume of the sulfur element than the common electron transport layer in the light-emitting region of the light-emitting element having the light-emitting layer with the longer emission peak wavelength. Hereinafter, a case will be described in which the light-emitting element having the light-emitting layer with the shorter emission peak wavelength is the green light-emitting element 10G, and the light-emitting element having the light-emitting layer with the longer emission peak wavelength is the red light-emitting element 10R. However, this is not limited thereto, and the light-emitting element having the light-emitting layer with the shorter emission peak wavelength may be the blue light-emitting element 10B, and the light-emitting element having the light-emitting layer with the longer emission peak wavelength may be the red light-emitting element 10R. Alternatively, the light-emitting element having the light-emitting layer with the shorter emission peak wavelength may be the blue light-emitting element 10B, and the light-emitting element having the light-emitting layer with the longer emission peak wavelength may be the green light-emitting element 10G. The electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G preferably has a lower concentration per unit volume of the sulfur element than the electron transport layer 6a in the light-emitting region RHR of the red light-emitting element 10R. This configuration reduces the difference between the conduction band minimum (CBM) of the quantum dots contained in the green light-emitting layer 5G and the conduction band minimum (CBM) of the electron transport layer 6c, as shown in FIG. 12 , and also reduces the difference between the conduction band minimum (CBM) of the quantum dots contained in the red light-emitting layer 5R and the conduction band minimum (CBM) of the electron transport layer 6a, thereby reducing the electron injection barrier in each of the green light-emitting element 10G and the red light-emitting element 10R. Furthermore, the electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G has a lower resistance than the electron transport layer 6b in the non-light-emitting region GNHR, thereby suppressing leakage current flowing through the electron transport layer 6b in the non-light-emitting region GNHR.

[0060] The green light-emitting element 10G shown in Figure 8 has a green functional layer 7G, and in this embodiment, the green functional layer 7G is described as being composed of a hole transport layer 4 containing a hole transport material, a green light-emitting layer 5G, and an electron transport layer 6c containing an electron transport material, as an example, but is not limited to this. The green light-emitting element 10G also has a light-emitting region GHR, a non-light-emitting region GNHR, a first end GNHRE1 which is the end of the non-light-emitting region GNHR closer to the light-emitting region GHR, a second end GNHRE2 which is the end of the non-light-emitting region RNHR farther from the light-emitting region GHR, the first region GNHR1 which is a region in the non-light-emitting region GNHR that is closer to the second end GNHRE2 than to the first end GNHRE1, and the second region GNHR2 which is a region in the non-light-emitting region GNHR that is closer to the first end GNHRE1 than to the second end GNHRE2.

[0061] FIG. 9 is a cross-sectional view showing a schematic configuration of another example of the red light emitting element 10R and the green light emitting element 10G that can be provided in the display area DA of the display device 1a of the first embodiment.

[0062] 9 differs from the display device 1 shown in Fig. 8 in that the electron transport layer 6a in the light-emitting region GHR of the green light-emitting element 10G has the same concentration per unit volume of the certain element, halogen or sulfur, as the electron transport layer 6a in the light-emitting region RHR of the red light-emitting element 10R. With this configuration, the electron transport layer 6a in the light-emitting region GHR of the green light-emitting element 10G has a lower resistance than the electron transport layer 6b in the non-light-emitting region GNHR, and therefore, leakage current flowing through the electron transport layer 6b in the non-light-emitting region GNHR can be suppressed.

[0063] FIG. 10 is a cross-sectional view showing a schematic configuration of an example of a red light emitting element 10R, a green light emitting element 10G, and a blue light emitting element 10B that can be provided in the display area DA of the display device 1 of the first embodiment.

[0064] 10 , the blue light-emitting element 10B includes a blue light-emitting layer 5B having a peak emission wavelength shorter than that of the green light-emitting layer 5G included in the green light-emitting element 10G. The electron transport layer 6d in the light-emitting region BHR of the blue light-emitting element 10B preferably has a lower concentration per unit volume of the halogen element, which is the one element, than the electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G. Furthermore, as described above, the electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G preferably has a lower concentration per unit volume of the halogen element, which is the one element, than the electron transport layer 6a in the light-emitting region RHR of the red light-emitting element 10R. 11 , it is possible to reduce the difference between the conduction band minimum (CBM) of the quantum dots contained in the blue light-emitting layer 5B and the conduction band minimum (CBM) of the electron transport layer 6 d, the difference between the conduction band minimum (CBM) of the quantum dots contained in the green light-emitting layer 5G and the conduction band minimum (CBM) of the electron transport layer 6 c, and the difference between the conduction band minimum (CBM) of the quantum dots contained in the red light-emitting layer 5R and the conduction band minimum (CBM) of the electron transport layer 6 a. Therefore, it is possible to reduce the electron injection barrier in each of the blue light-emitting element 10B, the green light-emitting element 10G, and the red light-emitting element 10R. The electron transport layer 6 a in the light-emitting region RHR of the red light-emitting element 10R has a higher concentration per unit volume of the halogen element, which is the one element that fills oxygen vacancies in the electron transport material, than the electron transport layer 6 c in the light-emitting region GHR of the green light-emitting element 10G, and therefore the electrical conductivity of the electron transport layer 6 a in the light-emitting region RHR of the red light-emitting element 10R is higher than the electrical conductivity of the electron transport layer 6 c in the light-emitting region GHR of the green light-emitting element 10G. Also, the electron transport layer 6 c in the light-emitting region GHR of the green light-emitting element 10G has a higher concentration per unit volume of the halogen element, which is the one element that fills oxygen vacancies in the electron transport material, than the electron transport layer 6 d in the light-emitting region BHR of the blue light-emitting element 10B, and therefore the electrical conductivity of the electron transport layer 6 c in the light-emitting region GHR of the green light-emitting element 10G is higher than the electrical conductivity of the electron transport layer 6 d in the light-emitting region BHR of the blue light-emitting element 10B.

[0065] The electron transport layer 6d in the light-emitting region BHR of the blue light-emitting element 10B preferably has a lower concentration per unit volume of the certain element sulfur than the electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G. Furthermore, as described above, the electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G preferably has a lower concentration per unit volume of the certain element sulfur than the electron transport layer 6a in the light-emitting region RHR of the red light-emitting element 10R. This configuration can reduce the difference between the conduction band minimum (CBM) of the quantum dots contained in the blue light-emitting layer 5B and the conduction band minimum (CBM) of the electron transport layer 6d, the difference between the conduction band minimum (CBM) of the quantum dots contained in the green light-emitting layer 5G and the conduction band minimum (CBM) of the electron transport layer 6c, and the difference between the conduction band minimum (CBM) of the quantum dots contained in the red light-emitting layer 5R and the conduction band minimum (CBM) of the electron transport layer 6a, as shown in FIG. 12 . This reduces the electron injection barrier in each of the blue light-emitting element 10B, the green light-emitting element 10G, and the red light-emitting element 10R. Furthermore, the electron transport layer 6d in the light-emitting region BHR of the blue light-emitting element 10B and the electron transport layer 6c in the light-emitting region GHR of the green light-emitting element 10G have lower resistance than the electron transport layer 6b in the non-light-emitting regions BNHR and GNHR, thereby suppressing leakage current flowing through the electron transport layer 6b in the non-light-emitting regions BNHR and GNHR.

[0066] The blue light-emitting element 10B shown in Figure 10 has a blue functional layer 7B, and in this embodiment, the blue functional layer 7B is described as being composed of a hole transport layer 4 containing a hole transport material, a blue light-emitting layer 5B, and an electron transport layer 6d containing an electron transport material, as an example, but is not limited to this. The blue light-emitting element 10B also comprises a light-emitting region BHR, a non-light-emitting region BNHR, a first end BNHRE1 which is the end of the non-light-emitting region BNHR closer to the light-emitting region BHR, a second end BNHRE2 which is the end of the non-light-emitting region BNHR farther from the light-emitting region BHR, a first region BNHR1 which is a region in the non-light-emitting region BNHR that is closer to the second end BNHRE2 than to the first end BNHRE1, and a second region BNHR2 which is a region in the non-light-emitting region BNHR that is closer to the first end BNHRE1 than to the second end BNHRE2.

[0067] Second Embodiment FIG. 13 is a cross-sectional view showing a schematic configuration of a red light emitting element 20R provided in a display area DA of a display device according to a second embodiment.

[0068] 13 includes an anode 2, a cathode 8, a red functional layer 7Ra provided between the anode 2 and the cathode 8, a light-emitting region RHR where the red functional layer 7Ra is in contact with both the anode 2 and the cathode 8, and a non-light-emitting region RNHR which is a region other than the light-emitting region RHR. The red functional layer 7Ra includes a red light-emitting layer 5R provided between the anode 2 and the cathode 8, and hole transport layers 4a and 4b containing a hole transport material provided between the red light-emitting layer 5R and the anode 2. In this embodiment, a case where the red functional layer 7Ra is composed of an electron transport layer 6b containing an electron transport material, the red light-emitting layer 5R, and hole transport layers 4a and 4b containing a hole transport material will be described as an example, but the present invention is not limited thereto. For example, the red functional layer 7Ra may be composed of the red light-emitting layer 5R and hole transport layers 4a and 4b containing a hole transport material.

[0069] As shown in FIG. 13 , two or more layers of the red functional layer 7Ra including at least the hole transport layers 4a and 4b, in this embodiment, three layers including the electron transport layer 6b including an electron transport material, the red light-emitting layer 5R, and the hole transport layers 4a and 4b, are formed across the light-emitting region RHR and the non-light-emitting region RNHR. However, this is not limited to this, and two layers, the red light-emitting layer 5R and the hole transport layers 4a and 4b, may be formed across the light-emitting region RHR and the non-light-emitting region RNHR, or two layers, the electron transport layer 6b including an electron transport material and the hole transport layers 4a and 4b, may be formed across the light-emitting region RHR and the non-light-emitting region RNHR.

[0070] As shown in FIG. 13 , in this embodiment, a case will be described as an example in which the hole transport layer 4 a in the light-emitting region RHR has a higher concentration per unit volume of a certain element that fills element vacancies (oxygen vacancies) that can become a source of hole scattering in the hole transport material, than the hole transport layer 4 b in the non-light-emitting region RNHR. However, this is not limited to this, and it is sufficient that the hole transport layer in the light-emitting region RHR includes a portion in which the concentration per unit volume of the certain element is higher than at least a portion of the hole transport layer in the non-light-emitting region RNHR. For example, a portion of the hole transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than a portion of the hole transport layer in the non-light-emitting region RNHR, a portion of the hole transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than a portion of the hole transport layer in the non-light-emitting region RNHR, the hole transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than a portion of the hole transport layer in the non-light-emitting region RNHR, or the hole transport layer in the light-emitting region RHR may have a higher concentration of the certain element per unit volume than the hole transport layer in the non-light-emitting region RNHR. The certain element is not particularly limited, but when the hole transport material contains, for example, oxygen element, as in the present embodiment, it is sufficient that the element can fulfill the function of filling oxygen vacancies that occur in the hole transport material. As the element that fulfills the function of filling such oxygen vacancies, for example, Group 16 elements and Group 17 elements can be suitably used, and it is preferable to use at least one of halogen elements and sulfur element. The certain element may be an element different from one or more elements that constitute the hole transport material, as long as it fulfills the function of filling oxygen vacancies that occur in the hole transport material.

[0071] 13 , in this embodiment, of the hole transport layers in the light-emitting region RHR and the non-light-emitting region RNHR, only the hole transport layer in the light-emitting region RHR contains the certain element. That is, the light-emitting region RHR is provided with a hole transport layer 4a containing the certain element, and the non-light-emitting region RNHR is provided with a hole transport layer 4b not containing the certain element. This is not limiting, and although not shown, the hole transport layer 4a containing the certain element may also be provided not only in the light-emitting region RHR but also in a portion of the second region RNHR2 closer to the light-emitting region RHR, which is a region in the non-light-emitting region RNHR that is closer to the first end RNHRE1 of the non-light-emitting region RNHR than to the second end RNHRE2 of the non-light-emitting region RNHR. Furthermore, at least a portion of the hole transport layer in the light-emitting region RHR may have a higher concentration per unit volume of the certain element than the hole transport layer in the first region RNHR1, which is closer to the second end RNHRE2 than to the first end RNHRE1 in the non-light-emitting region RNHR.

[0072] Furthermore, the hole transport layer of the light-emitting region RHR and the hole transport layer of the non-light-emitting region RNHR may each contain the same element, the hole transport layer of the light-emitting region RHR may have a higher concentration of the same element per unit volume than the hole transport layer of the non-light-emitting region RNHR, and the concentration of the same element per unit volume in the hole transport layer of the second region RNHR2 of the non-light-emitting region RNHR may be equal to or greater than the concentration of the same element per unit volume in the hole transport layer of the first region RNHR1 of the non-light-emitting region RNHR.

[0073] In this embodiment, the case where hole transport layers 4a and 4b are provided as charge transport layers between the red light-emitting layer 5R and the anode 2 will be described as an example. However, the present invention is not limited to this. The charge transport layers provided between the red light-emitting layer 5R and the anode 2 may include a hole injection layer, or may include a hole transport layer and a hole injection layer.

[0074] The hole transport layer 4b shown in FIG. 13 , which includes a hole transport material that does not contain one of the elements described above that can fill oxygen vacancies that occur in the hole transport material, is a conventional hole transport layer and includes hole scattering sources that cause high resistance. The hole transport material may be an inorganic material. When the hole transport material is a metal oxide or metal oxide particles containing at least one of Ni, Mg, Mo, Cu, Co, Cr, and Ti, it includes oxygen vacancies that are hole scattering sources that cause high resistance. In this embodiment, nickel oxide nanoparticles are used as the hole transport material, but this is not limited thereto. Here, the case where nickel oxide nanoparticles containing oxygen element are used as the hole transport material and the hole scattering sources are oxygen vacancies is described as an example, but this is not limited thereto. The hole transport material is not particularly limited as long as it includes element vacancies that can act as hole scattering sources.

[0075] As shown in Fig. 13, the hole transport layer 4a in the light-emitting region RHR contains the certain element (a halogen element in this embodiment). The certain element, a halogen element, fills oxygen vacancies, which are a source of hole scattering and cause high resistance, thereby reducing the influence of hole scattering and realizing low resistance in the hole transport layer 4a in the light-emitting region RHR. In the red light-emitting element 20R shown in Fig. 13, the light-emitting efficiency in the light-emitting region PHR can be improved. The hole transport layer 4b containing the hole transport material shown in Fig. 13, which does not contain the certain element, is a conventional hole transport layer and has not been subjected to any particular resistance-increasing treatment. However, the low resistance of the hole transport layer 4a in the light-emitting region RHR can suppress leakage current flowing through the hole transport layer 4b.

[0076] 13 , in this embodiment, a hole transport layer 4 a containing the certain element is provided in the light-emitting region RHR, and a hole transport layer 4 b not containing the certain element is provided in at least a portion of the non-light-emitting region RNHR. As described above, the certain element, a halogen element, fills the oxygen vacancies that are the source of hole scattering and cause high resistance, thereby reducing the influence of hole scattering and achieving low resistance of the hole transport layer 4 a in the light-emitting region RHR. Because the non-light-emitting region RNHR includes a hole transport layer 4 b not containing the certain element, the electrical conductivity of the hole transport layer in the non-light-emitting region RNHR is lower than the electrical conductivity of the hole transport layer 4 a in the light-emitting region RHR.

[0077] As the hole transport material, for example, inorganic materials such as metal oxides such as nickel oxide or nanoparticles of metal oxides such as nickel oxide can be suitably used, but organic materials may also be used as long as they cause element deficiencies that can become hole scattering sources.

[0078] The manufacturing method for red light-emitting element 20R shown in Fig. 13 differs from the manufacturing method for red light-emitting element 10R described in embodiment 1 with reference to Figs. 3, 4, and 5 only in that the film to which the certain element is added is a hole transport layer. Therefore, the manufacturing method for red light-emitting element 20R shown in Fig. 13 can be achieved by applying the method described in embodiment 1 with reference to Figs. 3, 4, and 5 to the hole transport layer, which is the film to which the certain element is added.

[0079] Although not shown, in the second embodiment, the configuration of the electron transport layer described above in the first embodiment may be adopted, and a configuration may be adopted in which the light-emitting region RHR is provided with a hole transport layer 4 a and an electron transport layer 6 a, and the non-light-emitting region RNHR is provided with a hole transport layer 4 b and an electron transport layer 6 b.

[0080] [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.

[0081] The present disclosure can be used in a light-emitting device, a display device, and a method for manufacturing a light-emitting device.

[0082] REFERENCE SIGNS LIST 1, 1a Display device 2 Anode 3 Bank 4, 4a, 4b Hole transport layer (charge transport layer) 5R Red light-emitting layer 5G Green light-emitting layer 5B Blue light-emitting layer 6, 6a to 6d Electron transport layer (charge transport layer) 7R Red functional layer 7G, 7G' Green functional layer 7B Blue functional layer 8 Cathode 10R Red light-emitting element (light-emitting element) 10G Green light-emitting element (light-emitting element) 10B Blue light-emitting element (light-emitting element) RSP Red pixel GSP Green pixel BSP Blue pixel PIX Display unit DA Display area NDA Frame area RHR, GHR, BHR Light-emitting area RNHR, GNHR, BNHR Non-light-emitting area RNHRE1, GNHRE1, BNHRE1 First end RNHRE2, GNHRE2, BNHRE2 Second end portion RNHR1, GNHR1, BNHR1 First region RNHR2, GNHR2, BNHR2 Second region ES Treatment liquid

Claims

1. A light-emitting element comprising: an anode; a cathode; a light-emitting layer provided between the anode and the cathode; a charge transport layer containing a charge transport material provided between the light-emitting layer and one of the anode and the cathode; a functional layer provided between the anode and the cathode; a light-emitting region where the functional layer is in contact with both the anode and the cathode; and a non-light-emitting region other than the light-emitting region, wherein two or more layers of the functional layers including at least the charge transport layer are formed across from the light-emitting region to the non-light-emitting region, and the charge transport layer in the light-emitting region comprises a portion where the concentration of a certain element per unit volume is higher than that of at least a portion of the charge transport layer in the non-light-emitting region.

2. The light-emitting element described in claim 1, wherein the end of the non-light-emitting region closer to the light-emitting region is defined as a first end, the end of the non-light-emitting region farther from the light-emitting region is defined as a second end, and a region of the non-light-emitting region that is closer to the second end than to the first end is defined as a first region, and at least a portion of the charge transport layer of the light-emitting region has a higher concentration of the one element per unit volume than the charge transport layer of the first region.

3. The light-emitting device according to claim 1 or 2, wherein, of the charge transport layer in the light-emitting region and the charge transport layer in the non-light-emitting region, only the charge transport layer in the light-emitting region contains the one element.

4. The light-emitting element described in claim 2, wherein the charge transport layer of the light-emitting region and the charge transport layer of the non-light-emitting region each contain the certain element, the charge transport layer of the light-emitting region has a higher concentration of the certain element per unit volume than the charge transport layer of the non-light-emitting region, a second region is a region of the non-light-emitting region that is closer to the first end of the non-light-emitting region than to the second end of the non-light-emitting region, and the concentration of the certain element per unit volume of the charge transport layer of the second region of the non-light-emitting region is equal to or greater than the concentration of the certain element per unit volume of the charge transport layer of the first region of the non-light-emitting region.

5. The light-emitting element according to claim 4, wherein the charge transport layer in the second region of the non-light-emitting region has a higher concentration of the one element per unit volume than the charge transport layer in the first region of the non-light-emitting region.

6. The light-emitting device according to any one of claims 1 to 5, wherein the one element is an element different from one or more elements constituting the charge transport material.

7. The light-emitting device according to any one of claims 1 to 6, wherein the charge transport material is an inorganic material.

8. The light-emitting element according to any one of claims 1 to 7, wherein the certain element is a halogen element.

9. The light-emitting element according to any one of claims 1 to 7, wherein the one element is sulfur.

10. The light-emitting device according to any one of claims 1 to 9, wherein the electrical conductivity of the charge transport layer in the non-light-emitting region is lower than the electrical conductivity of the charge transport layer in the light-emitting region.

11. A light-emitting element according to any one of claims 1 to 10, wherein the non-light-emitting region is provided with a bank, and two or more of the functional layers including at least the charge transport layer provided in the non-light-emitting region are separated from at least one of the anode and the cathode via the bank.

12. The light-emitting element described in claim 11, wherein the charge transport layer is formed across the light-emitting region and on the bank provided in the non-light-emitting region, and the electrical conductivity of the charge transport layer formed on the bank is lower than the electrical conductivity of the charge transport layer in the light-emitting region.

13. The light-emitting element described in claim 11, wherein the bank includes a slope formed at a forward taper angle, the charge transport layer is formed across the light-emitting region and the bank provided in the non-light-emitting region, and the electrical conductivity of the charge transport layer formed on the slope of the bank is lower than the electrical conductivity of the charge transport layer in the light-emitting region.

14. The light-emitting device according to any one of claims 1 to 13, wherein the charge transport layer is an electron transport layer or an electron injection layer.

15. The light-emitting element according to claim 14, wherein the charge transport material contained in the charge transport layer is a metal oxide containing at least one of Zn, Mg, Ti, Si, Sn, W, Ta, Ba, Zr, Al, Y, and Hf.

16. The light-emitting device according to any one of claims 1 to 13, wherein the charge transport layer is a hole transport layer or a hole injection layer.

17. The light-emitting device according to claim 16, wherein the charge transport material contained in the charge transport layer is a metal oxide containing at least one of Ni, Mg, Mo, Cu, Co, Cr, and Ti.

18. The light-emitting element according to claim 15 or 17, wherein the charge transport material is metal oxide particles.

19. The light-emitting device of any one of claims 1 to 18, wherein the light-emitting layer comprises an organic light-emitting material or quantum dots.

20. A display device comprising a plurality of light-emitting elements according to any one of claims 1 to 19.

21. The display device according to claim 20, wherein the charge transport layer is a common charge transport layer provided as one continuous film for a plurality of the light-emitting elements.

22. The display device described in claim 21, wherein the common charge transport layer is a common electron transport layer, the plurality of light-emitting elements include a first light-emitting element and a second light-emitting element, the first light-emitting element has a first light-emitting layer as the light-emitting layer, the second light-emitting element has a second light-emitting layer as the light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the first light-emitting layer, and the common electron transport layer in the light-emitting region of the second light-emitting element has a lower concentration of halogen elements per unit volume than the common electron transport layer in the light-emitting region of the first light-emitting element.

23. The display device described in claim 22, wherein the plurality of light-emitting elements include a third light-emitting element, the third light-emitting element having as the light-emitting layer a third light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the second light-emitting layer, and the common electron transport layer in the light-emitting region of the third light-emitting element has a lower concentration of halogen elements per unit volume than the common electron transport layer in the light-emitting region of the second light-emitting element.

24. The display device described in claim 21, wherein the common charge transport layer is a common electron transport layer, the plurality of light-emitting elements include a first light-emitting element and a second light-emitting element, the first light-emitting element has a first light-emitting layer as the light-emitting layer, and the second light-emitting element has a second light-emitting layer as the light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the first light-emitting layer, and the common electron transport layer in the light-emitting region of the second light-emitting element has a lower concentration of sulfur element per unit volume than the common electron transport layer in the light-emitting region of the first light-emitting element.

25. The display device described in claim 24, wherein the plurality of light-emitting elements include a third light-emitting element, the third light-emitting element having as the light-emitting layer a third light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the second light-emitting layer, and the common electron transport layer in the light-emitting region of the third light-emitting element has a lower concentration of sulfur element per unit volume than the common electron transport layer in the light-emitting region of the second light-emitting element.

26. The display device according to claim 22 or 24, wherein the electrical conductivity of the common electron transport layer in the light-emitting region of the first light-emitting element is higher than the electrical conductivity of the common electron transport layer in the light-emitting region of the second light-emitting element.

27. A display device as described in claim 23 or 25, wherein the electrical conductivity of the common electron transport layer in the light-emitting region of the first light-emitting element is higher than the electrical conductivity of the common electron transport layer in the light-emitting region of the second light-emitting element, and the electrical conductivity of the common electron transport layer in the light-emitting region of the second light-emitting element is higher than the electrical conductivity of the common electron transport layer in the light-emitting region of the third light-emitting element.

28. A display device according to any one of claims 20 to 27, wherein the non-light-emitting region is formed by extending the corresponding light-emitting layers provided for each of two adjacent light-emitting elements, and the non-light-emitting region includes a laminated portion in which the light-emitting layers provided for each of the two adjacent light-emitting elements are laminated.

29. A display device as described in any one of claims 23, 25, and 27, wherein the non-light-emitting region has formed therein a corresponding light-emitting layer provided for each of the first light-emitting element, the second light-emitting element, and the third light-emitting element, and the non-light-emitting region includes a stacked portion in which the light-emitting layers provided for each of the first light-emitting element, the second light-emitting element, and the third light-emitting element are stacked.

30. A display device according to any one of claims 23, 25, 27 and 29, wherein the first light-emitting layer is a red light-emitting layer, the second light-emitting layer is a green light-emitting layer, and the third light-emitting layer is a blue light-emitting layer.

31. A method for manufacturing a light-emitting element, comprising: a first step of forming one of an anode and a cathode; a second step of forming functional layers, the second step including a charge transport layer formation step of forming a charge transport layer containing a charge transport material, and a light-emitting layer formation step of forming a light-emitting layer; and a third step of forming the other of the anode and the cathode, wherein in the second step, two or more layers of the functional layers, including at least the charge transport layer, are formed across a light-emitting region, which is a region where the functional layer contacts both the anode and the cathode, and a non-light-emitting region, which is a region other than the light-emitting region, and after the charge transport layer formation step, an addition step of adding a certain element so that the charge transport layer in the light-emitting region includes a portion having a higher concentration of the certain element per unit volume than at least a portion of the charge transport layer in the non-light-emitting region.

32. A method for manufacturing a light-emitting element as described in claim 31, wherein an end of the non-light-emitting region closer to the light-emitting region is defined as a first end, an end of the non-light-emitting region farther from the light-emitting region is defined as a second end, and a region of the non-light-emitting region closer to the second end than to the first end is defined as a first region, and in the doping step, at least a portion of the charge transport layer in the light-emitting region has a higher concentration per unit volume of the one element than the charge transport layer in the first region.

33. A method for manufacturing a light-emitting element according to claim 31 or 32, wherein in the doping step, a mask having an opening is used to dope the one element into a region of the charge transport layer corresponding to the opening of the mask.

34. A method for manufacturing a light-emitting element as described in claim 31 or 32, wherein in the doping step, a resist film formed in a predetermined pattern is used to dope the one element into a region of the charge transport layer corresponding to a portion where the resist film is not formed.

35. A method for manufacturing a light-emitting element as described in claim 31 or 32, wherein in the light-emitting layer forming step, which is performed before the charge transport layer forming step, a light-emitting layer containing the one element is formed, and in the adding step, which is performed after the third step, a voltage is applied to the light-emitting region via the anode and the cathode, respectively, thereby moving the one element contained in the light-emitting layer in the light-emitting region to the charge transport layer in the light-emitting region.

36. A method for producing a light-emitting element according to any one of claims 31 to 35, wherein the one element is an element different from one or more elements constituting the charge transport material.

37. A method for manufacturing a light-emitting element according to any one of claims 31 to 36, wherein the certain element is a halogen element or a sulfur element.

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