Light-emitting element, light-emitting apparatus, and display apparatus

Abstract

A light-emitting element (1) has an upper electrode (UE) and a lower electrode (LE) that face each other, an electro-luminescence (EL) light-emitting layer (E) that receives carrier injection from the upper electrode (UE) and the lower electrode (LE) and emits EL light (81), and an insulating bank (BK) that is positioned on the side of the EL light-emitting layer (E). At least one of the upper electrode (UE) and the lower electrode (LE) is a light-transmitting electrode. The bank (BK) includes a photo-luminescence (PL) material (MP) that emits PL light (82). The main peak wavelength of the EL light (81) is denoted as λEL_PEAK, and the main peak wavelength of the PL light (82) is denoted as λPL_PEAK. The PL material (MP) absorbs light of the wavelength λEL_PEAK. In the light-emitting element (1), λPL_PEAK - 30 nm ≤ λEL_PEAK ≤ λPL_PEAK + 10 nm.

Description

Light-emitting element, light-emitting device, and display device

[0001] The following disclosure relates to a light-emitting element having an EL (Electro-Luminescent) light-emitting layer that emits EL light.

[0002] Various technologies have been proposed for devices using EL. For example, Patent Document 1 listed below discloses a technology aimed at improving the light extraction efficiency of an organic EL display device.

[0003] Japanese Patent Publication No. 2017-37825

[0004] An object of one embodiment of the present disclosure is to improve the performance of a light-emitting element having an EL light-emitting layer by using a structure different from that of a conventional one.

[0005] A light-emitting element according to one aspect of the present disclosure includes an upper electrode and a lower electrode facing each other, an EL light-emitting layer that receives carrier injection from the upper electrode and the lower electrode and emits electroluminescence (EL) light, and an insulating bank located on a side of the EL light-emitting layer, wherein at least one of the upper electrode and the lower electrode is a light-transmitting electrode, the bank contains a photoluminescence (PL) material that emits photoluminescence (PL), and the EL light has a main peak wavelength of λ ＥＬ＿ＰＥＡＫ and the main peak wavelength of the PL light is expressed as λ ＰＬ＿ＰＥＡＫ When the PL material is expressed as ＥＬ＿ＰＥＡＫ absorbs light of λ ＰＬ＿ＰＥＡＫ −30 nm≦λ ＥＬ＿ＰＥＡＫ ≦λ ＰＬ＿ＰＥＡＫ +10 nm.

[0006] According to one embodiment of the present disclosure, the performance of a light-emitting element having an EL light-emitting layer can be improved by using a configuration different from that of a conventional one.

[0007] 1 shows an example of the configuration of a light-emitting element in embodiment 1. 2 shows an example of the configuration of a light-emitting element in embodiment 2. 3 shows an example of the configuration of a light-emitting element in embodiment 3. 4 shows a diagram for explaining the relationship between the angle of PL light and radiance. 5 shows an example of the configuration of a light-emitting element in embodiment 4. 6 shows an example of the configuration of a light-emitting device in embodiment 5. 7 shows another example of the configuration of a light-emitting device in embodiment 6. 8 shows another example of the configuration of a light-emitting device in embodiment 7. 9 shows another example of the configuration of a light-emitting device in embodiment 8. 10 shows an example of the configuration of a light-emitting device in embodiment 9. 11 shows another example of the configuration of a light-emitting device in embodiment 9. 12 shows an example of the configuration of a display device in embodiment 10.

[0008] [Embodiment 1] Embodiment 1 will be described below. For convenience of explanation, components having the same functions as those described in embodiment 1 will be assigned the same reference numerals in the following embodiments, and their description will not be repeated. For simplicity, descriptions of well-known technical matters will also be omitted as appropriate. Unless otherwise specified, the components, materials, and numerical values ​​described in this specification are merely examples. Therefore, for example, unless otherwise specified, the positional relationship of the components is not limited to the examples in the figures. Furthermore, the figures are not necessarily drawn to scale.

[0009] FIG. 1 shows an example of the configuration of a light-emitting element 1 in embodiment 1. FIG. 1 schematically shows the layered structure of the light-emitting element 1. FIG. 1 shows one light-emitting element 1. For convenience of explanation, this specification introduces an orthogonal coordinate system (XYZ coordinate system) shown in FIG. 1. The Z direction in FIG. 1 is the thickness direction of each part of the light-emitting element 1. The Z direction in FIG. 1 is defined as the normal direction to the horizontal plane of the substrate SB of the light-emitting element 1.

[0010] In this specification, the positive direction of the Z direction will be described as the upward direction. Therefore, the negative direction of the Z direction is the downward direction. In the example of FIG. 1, the downward direction is defined as the direction toward the substrate SB of the light-emitting element 1. The X direction and Y direction in FIG. 1 are examples of directions that intersect with the Z direction. In this specification, of the two directions that intersect with the Z direction, the X direction will be mainly focused on.

[0011] The light-emitting element 1 includes an upper electrode UE and a lower electrode LE facing each other. The upper electrode UE may be either an anode or a cathode, and the lower electrode LE may be the other of the anode and the cathode. In embodiment 1, the lower electrode LE is an anode, and the upper electrode UE is a cathode.

[0012] 1 can be extracted to the outside of the light-emitting element 1. Therefore, in the light-emitting element 1, at least one of the upper electrode UE and the lower electrode LE may be a light-transmitting electrode. Either the upper electrode UE or the lower electrode LE may be a light-reflecting electrode.

[0013] The light-emitting element 1 includes a substrate SB that supports each part of the light-emitting element 1. In the example of Fig. 1, the substrate SB is located below the lower electrode LE. As shown in Fig. 1, the distance between the substrate SB and the lower electrode LE is smaller than the distance between the substrate SB and the upper electrode UE.

[0014] The light-emitting element 1 includes an EL layer E that receives carrier injection from the upper electrode UE and the lower electrode LE and emits EL light 81. The EL layer E may be located between the upper electrode UE and the lower electrode LE. In the example of embodiment 1, the lower electrode LE, which serves as an anode, supplies holes to the EL layer E, and the upper electrode UE, which serves as a cathode, supplies electrons to the EL layer E.

[0015] The EL layer E may contain any EL material that emits EL light 81 upon recombination of holes supplied from the anode and electrons transported from the cathode. Therefore, EL light 81 can be generated in the EL layer E by applying a voltage between the lower electrode LE and the upper electrode UE. In this specification, the main peak wavelength of the EL light (e.g., EL light 81) is defined as λ ＥＬ＿ＰＥＡＫ The main peak wavelength of the EL light is also referred to as the EL main peak wavelength.

[0016] The light-emitting element 1 includes an insulating bank BK located on a side of the EL light-emitting layer E. In the first embodiment, the X direction is used as an example of the direction representing "side." In the example of FIG. 1 , the light-emitting element 1 includes one bank BK on the side of the EL light-emitting layer E in the positive direction of the X direction (to the right in the plane of FIG. 1 ). The light-emitting element 1 also includes another bank BK on the side of the EL light-emitting layer E in the negative direction of the X direction (to the left in the plane of FIG. 1 ).

[0017] The bank BK may contain any PL material MP that emits PL light 82. For this reason, the bank BK may be referred to as a PL bank. As shown in FIG. 1, a portion of the EL light 81 emitted from the EL light-emitting layer E may enter the inside of the bank BK located to the side of the EL light-emitting layer E. The PL material MP may emit light having a wavelength λ ＥＬ＿ＰＥＡＫ Thus, for example, the PL material MP absorbs EL light 81 and emits PL light 82.

[0018] As an example, a portion of EL light 81 emitted from the EL layer E is incident on the upper electrode UE at a relatively large angle of incidence. The EL light 81 is totally reflected by the upper electrode UE and directed toward the inside of the bank BK. Therefore, by positioning the bank BK to the side of the EL layer E, the EL light 81 can be effectively received by the bank BK. As a result, PL light 82 can be effectively generated in the bank BK. In this specification, the main peak wavelength of the PL light (e.g., PL light 82) is defined as λ ＰＬ＿ＰＥＡＫ The main peak wavelength of PL light is also referred to as the main PL peak wavelength.

[0019] Unlike conventional light-emitting elements, the light-emitting element 1 can generate PL light 82 by utilizing a component of the EL light 81 that is not emitted to the outside of the light-emitting element 1. Therefore, by extracting the PL light 82 to the outside of the light-emitting element 1, a higher light extraction efficiency can be achieved than with conventional light-emitting elements.

[0020] In conventional light-emitting elements, when EL light is converted to PL light, the color of the PL light is generally made different from the color of the EL light. In contrast, in embodiment 1, the light-emitting element 1 is configured so that the color of the PL light 82 is as close as possible to the color of the EL light 81. This is because the closer the color of the PL light 82 is to the color of the EL light 81, the more improved the color purity of the light extracted to the outside of the light-emitting element 1 (i.e., the mixed light of the EL light 81 and the PL light 82).

[0021] Therefore, in the first embodiment, λ ＰＬ＿ＰＥＡＫ is λ ＥＬ＿ＰＥＡＫ Specifically, the light-emitting element 1 is configured so that the following formula (1) is satisfied: λ ＰＬ＿ＰＥＡＫ −30 nm≦λ ＥＬ＿ＰＥＡＫ ≦λ ＰＬ＿ＰＥＡＫ The EL material and the PL material MP are selected so that the following relation is satisfied: +10 nm (1).

[0022] Generally, a PL material converts EL light having a certain main peak wavelength into PL light having a main peak wavelength of PL light longer than the main peak wavelength of EL light. ＥＬ＿ＰＥＡＫ <λ ＰＬ＿ＰＥＡＫ ...(2) can be satisfied.

[0023] However, depending on the spectrum of the EL light, for example, the PL material may be excited by EL light having a main EL peak wavelength greater than the main PL peak wavelength. ＰＬ＿ＰＥＡＫ is λ ＥＬ＿ＰＥＡＫ It is assumed that it can take a value smaller than

[0024] By configuring the light-emitting element 1 so that formula (1) is satisfied, it is possible to improve the color purity of the light extracted to the outside of the light-emitting element 1 compared to conventional techniques. It is also possible to improve the brightness of the light extracted to the outside of the light-emitting element 1 compared to conventional techniques. As described above, the light-emitting element 1 can improve the performance of the light-emitting element by using a novel configuration that differs from conventional techniques.

[0025] Furthermore, by configuring the light-emitting element 1 so that formula (2) is satisfied, the PL material MP can be more effectively excited by the EL light 81. In other words, the EL light 81 can be more effectively utilized to generate the PL light 82. Therefore, it is preferable that the light-emitting element 1 is configured so that formula (2) is satisfied.

[0026] Preferably, the EL light 81 has a single peak wavelength. When the EL light 81 has a single peak wavelength, the PL material is less likely to be excited by components of the EL light 81 that have excess energy, compared to when the EL light 81 has multiple peak wavelengths. This reduces the amount of heat generated when the PL material emits PL light 82. As a result, the stability of the light-emitting element 1 can be improved.

[0027] When the EL light 81 has a single peak wavelength, it is desirable that the half-width of the emission spectrum of the EL light 81 be as small as possible. This is because a smaller half-width makes it less likely that the PL material will be excited by components of the EL light 81 that have excess energy. As an example, the half-width may be 40 nm or less. In this case, the amount of heat generated when the PL material emits the PL light 82 can be further reduced, thereby further improving the stability of the light-emitting element 1.

[0028] As described above, the bank BK has insulating properties. Therefore, the bank BK may contain any insulating material. Therefore, for example, the bank BK may contain a resin. As an example, the resin content in the bank BK may be 30 weight percent or more.

[0029] The resin in the bank BK may be a photocurable resin. Use of a photocurable resin facilitates the manufacture of the light-emitting element 1 by an optical process (e.g., photolithography). Therefore, use of a photocurable resin can improve the mass productivity of the light-emitting element 1.

[0030] In addition, increasing the thickness of the bank BK can also improve the insulating properties of the bank BK. As an example, the thickness of the bank BK may be 300 nm or more. By setting the thickness of the bank BK to 300 nm or more, the bank BK can be given good insulating properties. As a result, current leakage in the light-emitting element 1 is reduced. Therefore, the light-emitting efficiency of the light-emitting element 1 is improved.

[0031] The bank BK may contain quantum dots (QDs) as the PL material MP. Using QDs as the PL material MP can improve the monochromaticity of the PL light 82. In this manner, the bank BK may contain a mixture of QDs and a resin.

[0032] The bank BK may include PL core-shell QDs. In this case, for example, the PL core-shell QDs may have a PL core as a PL material MP and a PL shell covering the PL core.

[0033] The PL material MP is preferably insulating, unlike the EL light-emitting material. The PL shell may be formed in multiple layers. The PL core may be an insulator. For example, the PL core is 10 nm or thicker than the PL shell. Examples of insulating PL core materials include silica and alumina.

[0034] The EL layer E may also include EL core-shell QDs. In this case, for example, the EL core-shell QDs may have an EL core as an EL material and an EL shell covering the EL core.

[0035] Unlike the bank BK, the EL layer E does not need to be insulating. Rather, from the viewpoint of the electrical properties of the EL layer E, it is preferable that the EL layer E have some degree of conductivity. Therefore, for example, the thickness of the EL shell may be set smaller than the thickness of the PL shell. In other words, the thickness of the PL shell may be set larger than the thickness of the EL shell.

[0036] By setting the thickness of the EL shell to a small value as described above, the electrical characteristics of the EL light-emitting layer E can be improved. On the other hand, by setting the thickness of the PL shell to a small value as described above, the PL core can be more reliably protected from damage caused by resin mixing. In addition, concentration quenching in the PL core can be reduced. As a result, the PL luminous efficiency of the light-emitting element 1 can be improved.

[0037] From the viewpoint of facilitating the manufacture of the light-emitting element 1, it is preferable to minimize the number of types of raw materials involved in the manufacture of the light-emitting element 1. From this viewpoint, the PL material MP may be the same as the EL material.

[0038] From the viewpoint of reducing concentration quenching in the PL material MP, it is desirable that the content of the PL material MS in the bank BK is not too high. As an example, the content of the PL material MS in the bank BK may be less than 50 weight percent. By setting the content of the PL material MS in the bank BK in this manner, the PL luminous efficiency of the light-emitting element 1 can also be improved.

[0039] However, light may be reflected at the interface between two objects having different refractive indices. Therefore, the light-emitting element 1 may have multiple light-reflecting surfaces. In FIG. 1 , a first light-reflecting surface RF1 and a second light-reflecting surface RF2, which are parallel to each other, are shown as examples of light-reflecting surfaces. For example, the first light-reflecting surface RF1 may be the interface between the upper electrode UE and air. The second light-reflecting surface RF2 may be the interface between the lower electrode LE and the substrate SB.

[0040] 1, at least a portion of the bank BK can be sandwiched between the first light reflecting surface RF1 and the second light reflecting surface RF2. The first light reflecting surface RF1 and the second light reflecting surface RF2 will be described in more detail in the third embodiment described below.

[0041] [Embodiment 2] Fig. 2 shows a configuration example of a light-emitting element 1 according to embodiment 2. In the example of Fig. 2, the light-emitting element 1 has a planarization film FF in an EL light-emitting region ELA. The EL light-emitting region ELA refers to a region in the light-emitting element 1 where EL light 81 is emitted from the EL light-emitting layer E upon receiving carrier injection from the upper electrode UE and the lower electrode LE. Therefore, the EL light-emitting region ELA does not overlap with the bank BK when viewed from the Z direction.

[0042] 2, the lower electrode LE is located above the planarization film FF in the EL light-emitting region ELA, so that at least a part of the bank BK can be located below the lower electrode LE in the EL light-emitting region ELA, as shown in FIG.

[0043] By positioning at least a portion of the bank BK below the lower electrode LE in the EL light-emitting region ELA, the volume of the bank BK can be increased. This increases the distance that the EL light 81 travels within the bank BK, allowing the PL material MS in the bank BK to more effectively absorb the EL light 81. This improves the luminous efficiency of the light-emitting element 1.

[0044] Furthermore, by positioning at least a portion of the bank BK below the lower electrode LE in the EL light-emitting region ELA, the upward protrusion length of the bank BK can be reduced even when the bank BK has a large thickness.

[0045] [Embodiment 3] Figure 3 shows a configuration example of a light-emitting element 1 in embodiment 3. The light-emitting element 1 in embodiment 3 has a metal reflective film MF located above or below the bank BK. The upper electrode UE or the lower electrode LE can be used as the metal reflective film MF. Figure 3 shows, as an example, a case where the lower electrode LE is the metal reflective film MF. The metal reflective film MF may be provided as a component separate from the upper electrode UE and the lower electrode LE.

[0046] The light-emitting element 1 in the third embodiment has a light-transmitting film TF located between the bank BK and the metal reflective film MF. In the example of Fig. 3, the light-transmitting film TF is located between the bank BK and the lower electrode LE.

[0047] 3 also shows a first light reflecting surface RF1 and a second light reflecting surface RF2 that are parallel to each other, as in the example of Fig. 1. Also in the example of Fig. 3, at least a portion of the bank BK can be sandwiched between the first light reflecting surface RF1 and the second light reflecting surface RF2.

[0048] This positional relationship allows the first light reflecting surface RF1 and the second light reflecting surface RF2 to reinforce each other's main peak wavelength components of the PL light 82 in the Z direction. For example, the first light reflecting surface RF1 and the second light reflecting surface RF2 can reinforce each other's main peak wavelength components of the PL light 82 due to a resonance effect. As a result, the brightness of the PL light 82 emitted to the outside of the light-emitting element 1 can be improved.

[0049] The resonant structure formed by the first light reflecting surface RF1 and the second light reflecting surface RF2 can intensify light. If the resonant structure completely intensifies light, the following equation (3) holds true:

[0050] In equation (3), m is the order of resonance. Ｄ represents the phase shift due to reflection at the second light reflecting surface RF2. Ｕrepresents the phase shift due to reflection at the first light reflecting surface RF1. λ is the peak wavelength of light. n is the refractive index of the intermediate layer located between the first light reflecting surface RF1 and the second light reflecting surface RF2. d is the distance between the first light reflecting surface RF1 and the second light reflecting surface RF2 in the normal direction of the first light reflecting surface RF1 and the second light reflecting surface RF2, which are parallel to each other. φ is the angle formed between either the first light reflecting surface RF1 or the second light reflecting surface RF2 (e.g., the second light reflecting surface RF2) and the substrate SB.

[0051] The resonant structure described above may also attenuate light. If the resonant structure completely attenuates light, then the following equation (4) holds: Equation (4) is a counterpart to equation (3).

[0052] In embodiment 3, θ Ｄ and θ Ｕ In the formula (3), the order m corresponding to a certain distance d is set to be a natural number. Ｄ and θ Ｕ is set so that the following equation (5) holds.

[0053] In this specification, the value of the distance d when equation (3) is satisfied at the order m is defined as D ｍ In addition, the value of the distance d when the formula (4) is satisfied in the order m is expressed as d ｍ In a resonant structure that intensifies light, it is preferable that the following formula (6-1) holds, it is more preferable that the following formula (6-2) holds, and it is even more preferable that the following formula (6-3) holds. When formulas (6-1) to (6-3) are generalized using a natural number k, the following formula (6-4) is obtained.

[0054] Equations (6-1), (6-2), and (6-3) correspond to the cases of k = 1, k = 2, and k = 4 in equation (6-4), respectively. As can be understood from this, in a resonant structure that intensifies light, it is preferable that equation (6-4) holds true for a larger k.

[0055] On the other hand, in a resonant structure that weakens light, it is preferable that the following formula (7-1) holds, it is more preferable that the following formula (7-2) holds, and it is even more preferable that the following formula (7-3) holds. When formulas (7-1) to (7-3) are generalized using a natural number k, the following formula (7-4) is obtained. Formula (7-4) is a paired formula with formula (6-4).

[0056] Equations (7-1), (7-2), and (7-3) correspond to the cases of k = 1, k = 2, and k = 4 in equation (7-4), respectively. As can be understood from this, in a resonant structure that attenuates light, it is preferable that equation (7-4) holds true for a larger k.

[0057] From the above, by using equation (6-4), it is possible to mathematically evaluate how the first light reflecting surface RF1 and the second light reflecting surface RF2 strengthen the main peak wavelength component of the PL light 82. Furthermore, by using equation (7-4), it is possible to mathematically evaluate how the first light reflecting surface RF1 and the second light reflecting surface RF2 weaken the main peak wavelength component of the PL light 82.

[0058] 3 again, the above-described light-transmitting film TF can reduce plasmon absorption in the metal reflective film MF, thereby improving the light extraction efficiency of the PL light 82 in the light-emitting element 1.

[0059] In the light-emitting element 1, the bank BK may be manufactured using a material that does not have light-scattering properties. The bank BK that does not have light-scattering properties can prevent scattering of the PL light 82, for example, in the region sandwiched between the first light-reflecting surface RF1 and the second light-reflecting surface RF2. When scattering of the PL light 82 does not occur, the coherence of the PL light 82 is improved, and the first light-reflecting surface RF1 and the second light-reflecting surface RF2 can reinforce each other more effectively the main peak wavelength component of the PL light 82.

[0060] From the viewpoint of improving the coherence of the PL light 82, it is preferable that the refractive index in the region sandwiched between the first light reflecting surface RF1 and the second light reflecting surface RF2 is as constant as possible. As an example, in the light-emitting element 1, in each part belonging to the region sandwiched between the first light reflecting surface RF1 and the second light reflecting surface RF2, the refractive index is set to half the main peak wavelength of the PL light (i.e., λ ＰＬ＿ＰＥＡＫ 1 / 2), the refractive index may be constant when observed on a scale longer than 1 / 2. If this condition is met, further improvement in the coherence of the PL light 82 may occur.

[0061] In order for the first light reflecting surface RF1 and the second light reflecting surface RF2 to effectively reinforce each other's PL light 82, it is preferable that the first light reflecting surface RF1 and the second light reflecting surface RF2 are not too far apart. Therefore, for example, the distance between the first light reflecting surface RF1 and the second light reflecting surface RF2 may be greater than 0 μm and equal to or less than 1 μm.

[0062] 4 is a diagram illustrating the relationship between the angle of the PL light 82 (more specifically, the angle of the optical axis of the PL light 82) and radiance. In this specification, the angle that the PL light 82 makes with respect to the Z direction is represented as θ. The radiance of the PL light 82 that makes the angle θ with respect to the Z direction is represented as RM(θ).

[0063] 4 illustrates the case where 0°≦θ≦90°. In the example of Fig. 4, when θ = 0°, the direction of the PL light 82 coincides with the positive direction of the Z direction. On the other hand, when θ = 90°, the direction of the PL light 82 coincides with the positive direction of the X direction.

[0064] As shown in Fig. 4, consider two angles θ1 and θ2 that satisfy the relationship θ1 < θ2. In the example of Fig. 4, PL light 82A forms an angle θ1, and PL light 82B forms an angle θ2. In the light-emitting element 1, as θ increases, the mismatch between the direction of PL light 82 and the Z direction becomes more pronounced. Therefore, as θ increases, it becomes more difficult for the first light reflecting surface RF1 and the second light reflecting surface RF2 to intensify the PL light 82.

[0065] As a result, RM(θ) can decrease significantly with an increase in θ in the light-emitting element 1. Therefore, in the light-emitting element 1, for example, when 0°≦θ1<θ2<70°, θ1 and θ2 can exist that satisfy the following formula (8): RM(θ2) / RM(θ1)≦0.7 (8).

[0066] [Embodiment 4] Fig. 5 shows a configuration example of a light-emitting element 1 in embodiment 4. In the example of Fig. 5, the bank BK has a non-light-emitting portion NE inside the bank BK. Therefore, in the example of Fig. 5, the light-emitting portion of the bank BK (the portion including the PL material MP) is located outside the bank BK. The symbol SS in Fig. 5 represents the slope of the bank BK. The slope SS in the example of Fig. 5 is the outer slope of the bank BK, i.e., the slope of the light-emitting portion of the bank BK.

[0067] 5 shows the first light reflecting surface RF1 and the second light reflecting surface RF positioned on either side of the slope SS. In this manner, the slope SS can be positioned between the first light reflecting surface RF1 and the second light reflecting surface RF2.

[0068] For example, the surface of the non-light-emitting portion NE may be light-reflective, and the second light-reflecting surface RF2 in Fig. 5 may be, for example, the interface between the non-light-emitting portion NE and the light-emitting portion of the bank BK.

[0069] Since the slope SS is located between the first light reflecting surface RF1 and the second light reflecting surface RF, the PL light 82 generated near the slope SS can be constructively reflected by the first light reflecting surface RF1 and the second light reflecting surface RF. For example, the main peak wavelength component of the PL light 82 in the Z direction can be constructively reflected by the first light reflecting surface RF1 and the second light reflecting surface RF.

[0070] 5, the thickness of the non-emitting portion NE of the bank BK may be set to be larger than the thickness of the EL layer E. This allows the first light reflecting surface RF1 and the second light reflecting surface RF to more effectively reinforce each other the main peak wavelength component of the PL light 82 in the Z direction.

[0071] [Embodiment 5] Fig. 6 shows a configuration example of a light-emitting device 10 according to embodiment 5. In Fig. 6, reference numeral 610 schematically indicates a cross-sectional structure of the light-emitting device 10, and reference numeral 620 schematically indicates a planar layout of the light-emitting device 10. A light-emitting device according to one aspect of the present disclosure may include a light-emitting element according to one aspect of the present disclosure. In embodiment 5, a case where the light-emitting device 10 includes a plurality of light-emitting elements 1 is illustrated.

[0072] 6, the light emitting device 10 may have a first light emitting element 1-1 and a second light emitting element 1-2 adjacent to the first light emitting element 1-1 as the plurality of light emitting elements 1. In this specification, "adjacent" refers to "adjacent in the lateral direction (X direction)" unless otherwise specified.

[0073] The first light-emitting element 1-1 has a first upper electrode UE1 as the upper electrode UE and a first lower electrode LE1 as the lower electrode LE. The first light-emitting element 1-1 has a first EL light-emitting layer E1 as the EL light-emitting layer E. The first EL light-emitting layer E1 emits first EL light upon receiving carrier injection from the first upper electrode UE1 and the first lower electrode LE1. The first light-emitting element 1-1 has a first bank BK1 as the bank BK. The first bank BK1 is located on the side of the first EL light-emitting layer E1.

[0074] The second light-emitting element 1-2 has a second upper electrode UE2 as the upper electrode UE and a second lower electrode LE2 as the lower electrode LE. The second light-emitting element 1-2 has a second EL light-emitting layer E2 as the EL light-emitting layer E. The second EL light-emitting layer E2 emits second EL light upon receiving carrier injection from the second upper electrode UE2 and the second lower electrode LE2. The second light-emitting element 1-2 has a second bank BK2 as the bank BK. The second bank BK2 is located on the side of the second EL light-emitting layer E2.

[0075] 6, a first bank BK1 and a second bank BK2 are located between the first EL light-emitting layer E1 and the second EL light-emitting layer E2. That is, the first EL light-emitting layer E1 and the second EL light-emitting layer E2 are separated by the first bank BK1 and the second bank BK2.

[0076] In this specification, the main peak wavelength of the first EL light is referred to as the “first EL main peak wavelength,” and the main peak wavelength of the second EL light is referred to as the “second EL main peak wavelength.” In the light-emitting device according to one aspect of the present disclosure, the first EL main peak wavelength and the second EL main peak wavelength may be the same or different.

[0077] In the fifth embodiment, a case where the first EL main peak wavelength and the second EL main peak wavelength are different from each other is illustrated. Specifically, in the fifth embodiment, a case where the first EL main peak wavelength is longer than the second EL main peak wavelength is illustrated.

[0078] In the fifth embodiment, a case where each of the multiple banks BK (e.g., a first bank BK1 and a second bank BK2) contains a different PL material MP is illustrated. In the fifth embodiment, the first bank BK1 contains a first PL material MP1 as the PL material MP. The first PL material MP1 absorbs the first EL light and emits the first PL light. The second bank BK2 contains a second PL material MP2 as the PL material MP. The second PL material MP2 absorbs the second EL light and emits the second PL light.

[0079] In this specification, the main peak wavelength of the first PL light is referred to as the “first PL main peak wavelength,” and the main peak wavelength of the second PL light is referred to as the “first PL main peak wavelength.” In the example of the fifth embodiment, the first PL main peak wavelength is longer than the second PL main peak wavelength.

[0080] Generally, the distance between the first light reflecting surface RF1 and the second light reflecting surface RF2 for intensifying a certain PL light by the resonance effect increases as the main peak wavelength of the PL light increases. For this reason, in the example of Fig. 6, the height of the first bank BK1 is set to be greater than the height of the second bank BK2. This allows the first PL light to be intensified by the resonance effect of the first bank BK1, and the second PL light to be intensified by the resonance effect of the second bank BK2.

[0081] Fig. 7 shows another example of the configuration of the light-emitting device 10 according to the fifth embodiment. In Fig. 7, reference numeral 710 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 720 schematically indicates the planar layout of the light-emitting device 10. The light-emitting device 10 in the example of Fig. 7 further includes a third light-emitting element 1-3 as one of the plurality of light-emitting elements 1. The third light-emitting element 1-3 is adjacent to the second light-emitting element 1-2 on the side opposite to the first light-emitting element 1-1.

[0082] The third light-emitting element 1-3 has a third upper electrode UE3 as the upper electrode UE and a third lower electrode LE3 as the lower electrode LE. The third light-emitting element 1-3 has a third EL light-emitting layer E3 as the EL light-emitting layer E. The third EL light-emitting layer E3 receives carrier injection from the third upper electrode UE3 and the third lower electrode LE3 and emits third EL light. The third light-emitting element 1-3 has a third bank BK3 as the bank BK. The third bank BK3 is located on the side of the third EL light-emitting layer E3.

[0083] 7, the second bank BK2 and the third bank BK3 are located between the second EL light-emitting layer E2 and the third EL light-emitting layer E3. That is, the second EL light-emitting layer E2 and the third EL light-emitting layer E3 are separated by the second bank BK2 and the third bank BK3.

[0084] In this specification, the main peak wavelength of the third EL light is referred to as the third EL main peak wavelength. In the fifth embodiment, a case where the second EL main peak wavelength is longer than the third EL main peak wavelength is illustrated. In this manner, in the fifth embodiment, the third EL main peak wavelength is shorter than the second EL main peak wavelength, and the second EL main peak wavelength is shorter than the first EL main peak wavelength.

[0085] In the fifth embodiment, the third bank BK3 includes a third PL material MP3 as the PL material MP. The third PL material MP3 absorbs the third EL light and emits the third PL light. In the example of the fifth embodiment, the second PL main peak wavelength is longer than the third PL main peak wavelength. Thus, in the fifth embodiment, the third PL main peak wavelength is shorter than the second PL main peak wavelength, and the second PL main peak wavelength is shorter than the first PL main peak wavelength.

[0086] 7, the height of the second bank BK2 is set to be greater than the height of the third bank BK3. Thus, in the fifth embodiment, the height of the third bank BK3 is smaller than the height of the second bank BK2, and the height of the second bank BK2 is smaller than the height of the first bank BK1.

[0087] 7, the first EL light may be red EL light, the second EL light may be green EL light, and the third EL light may be blue EL light, so the first EL light-emitting layer E1 may be a red EL light-emitting layer, the second EL light-emitting layer E2 may be a green EL light-emitting layer, and the third EL light-emitting layer E3 may be a blue EL light-emitting layer.

[0088] In this case, for example, the first PL light may be red PL light, the second EL light may be green PL light, and the third EL light may be blue PL light, so that the first PL material MP1 may be a red PL material, the second PL material MP2 may be a green PL material, and the third PL material MP3 may be a blue PL material.

[0089] As described above, the first light-emitting element 1-1 may be a red light-emitting element, the second light-emitting element 1-2 may be a green light-emitting element, and the third light-emitting element 1-3 may be a blue light-emitting element. In this case, for example, the first EL main peak wavelength may be 630 nm and the first PL main peak wavelength may be 640 nm. The second EL main peak wavelength may be 530 nm and the second PL main peak wavelength may be 540 nm. The third EL main peak wavelength may be 460 nm and the third PL main peak wavelength may be 470 nm.

[0090] [Embodiment 6] Fig. 8 shows an example of the configuration of a light-emitting device 10 according to embodiment 6. Like Fig. 6, Fig. 8 illustrates a light-emitting device 10 having two types of light-emitting elements, a first light-emitting element 1-1 and a second light-emitting element 1-2. In Fig. 8, reference numeral 810 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 820 schematically indicates the planar layout of the light-emitting device 10.

[0091] Unlike the fifth embodiment, the sixth embodiment illustrates a case in which each of the plurality of banks BK (e.g., a first bank BK1 and a second bank BK2) contains the same PL material MP. In this case, the manufacturing of the plurality of banks BK is easier than in the fifth embodiment. Furthermore, the brightness of the PL light emitted from the light-emitting device 10 can also be increased.

[0092] In the sixth embodiment, the first bank BK1 and the second bank BK2 each contain a PL material MP that absorbs the second EL light and emits PL light. In the sixth embodiment, the PL main peak wavelength is preferably longer than the second EL main peak wavelength and shorter than the first EL main peak wavelength. In this case, for example, the PL material MP can be excited only by the second EL light. That is, the PL material MP is not excited by the first EL light. This reduces the risk of color mixing due to PL light in the light-emitting device 10.

[0093] As described above, in the sixth embodiment, the first bank BK1 and the second bank BK each contain the same PL material MP, and therefore, in the example of Fig. 8, the height of the first bank BK1 is set to be the same as the height of the second bank BK2.

[0094] 8, the light-emitting device 10 may have a conductive reflective film CR. Two adjacent banks BK (e.g., a first bank BK1 and a second bank BK2) may form a valley VL between the two BKs. In the example of FIG. 8, the conductive reflective film CR is located on the upper surface of the valley VL between the first bank BK1 and the second bank BK2.

[0095] 8 can reduce the resistance of the upper electrode UE, thereby improving the EL light emission efficiency of the light emitting device 10. Furthermore, the conductive reflective film CR in FIG. 8 can also reduce the risk of color mixing caused by PL light in the light emitting device 10.

[0096] Fig. 9 shows another example of the configuration of the light-emitting device 10 in embodiment 6. Like Fig. 7, Fig. 9 shows a light-emitting device 10 having three types of light-emitting elements: a first light-emitting element 1-1, a second light-emitting element 1-2, and a third light-emitting element 1-3. In Fig. 9, reference numeral 910 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 920 schematically indicates the planar layout of the light-emitting device 10.

[0097] 9 illustrates an example in which the first bank BK1, the second bank BK2, and the third bank BK3 each contain a PL material MP that absorbs the third EL light and emits PL light. In the example of FIG. 9, the PL main peak wavelength is preferably longer than the third EL main peak wavelength and shorter than the second EL main peak wavelength. In this case, for example, the PL material MP can be excited only by the third EL light. In other words, it is possible to prevent the PL material MP from being excited by either the first EL light or the second EL light.

[0098] 9, the second bank BK2 and the third bank BK3 can form a valley VL between them. In the example of Fig. 9, the conductive reflective film CR is also located on the upper surface of the valley VL between the second bank BK2 and the third bank BK3.

[0099] 9, consider a case where the first EL layer E1 is a red EL layer, the second EL layer E2 is a green EL layer, and the third EL layer E3 is a blue EL layer. In this case, for example, the PL light may be blue PL light. Therefore, the PL material MP may be a blue PL material.

[0100] As described above, even when one type of PL material (e.g., blue PL material) is used, it is possible to realize the first light-emitting element 1-1 as a red light-emitting element, the second light-emitting element 1-2 as a green light-emitting element, and the third light-emitting element 1-3 as a blue light-emitting element. In this case, for example, the first EL main peak wavelength may be 630 nm, the second EL main peak wavelength may be 530 nm, the third EL main peak wavelength may be 460 nm, and the PL main peak wavelength may be 470 nm.

[0101] [Embodiment 7] Fig. 10 shows an example of the configuration of a light-emitting device 10 according to embodiment 7. Like Fig. 6, Fig. 10 illustrates a light-emitting device 10 having two types of light-emitting elements, a first light-emitting element 1-1 and a second light-emitting element 1-2. In Fig. 10, reference numeral 1010 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 1020 schematically indicates the planar layout of the light-emitting device 10.

[0102] In the seventh embodiment, similar to the fifth embodiment, a case is illustrated in which each of the multiple banks BK contains a different PL material MP. In the example of Fig. 10, similar to the example of Fig. 6, the first bank BK1 contains a first PL material MP1, and the second bank BK2 contains a second PL material MP2. Therefore, similar to the example of Fig. 6, the height of the first bank BK1 in the example of Fig. 10 is greater than the height of the second bank BK2.

[0103] In the same manner as in the sixth embodiment, the seventh embodiment illustrates a case in which the light-emitting device 10 includes a conductive reflective film CR. In the example of Fig. 10, the conductive reflective film CR is located on the upper surface of the valley VL between the first bank BK1 and the second bank BK2. In this way, the conductive reflective film CR may be provided even when the height of the first bank BK1 and the height of the second bank BK2 are different.

[0104] Fig. 11 shows another example of the configuration of the light-emitting device 10 in embodiment 7. Like Fig. 7, Fig. 11 shows an example of a light-emitting device 10 having three types of light-emitting elements: a first light-emitting element 1-1, a second light-emitting element 1-2, and a third light-emitting element 1-3. In Fig. 11, reference numeral 1110 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 1120 schematically indicates the planar layout of the light-emitting device 10.

[0105] In the example of Fig. 11, the third bank BK3 contains the third PL material MP3, as in the example of Fig. 7. Therefore, in the example of Fig. 11, the height of the second bank BK2 is greater than the height of the third bank BK3, as in the example of Fig. 7. In the example of Fig. 11, the conductive reflective film CR is also located on the upper surface of the valley portion VL between the second bank BK2 and the third bank BK3.

[0106] [Embodiment 8] Fig. 12 shows an example of the configuration of a light-emitting device 10 according to embodiment 8. Like Fig. 6, Fig. 12 shows a light-emitting device 10 having two types of light-emitting elements, a first light-emitting element 1-1 and a second light-emitting element 1-2. In Fig. 12, reference numeral 1210 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 1220 schematically indicates the planar layout of the light-emitting device 10.

[0107] In the embodiment 8, similar to the embodiment 6, a case is illustrated in which each of the multiple banks BK contains the same PL material MP. In the example of Fig. 12, similar to the example of Fig. 8, the first bank BK1 and the second bank BK2 each contain a PL material MP that absorbs the second EL light and emits PL light. Therefore, in the example of Fig. 12, similar to the example of Fig. 8, the first bank BK1 and the second bank BK2 each have the same height.

[0108] In the example of Fig. 12, unlike the example of Fig. 8, two adjacent banks BK do not form a valley portion VL between the two BK. In this case, as shown in Fig. 12, the light-emitting device 10 does not need to have a conductive reflective film CR. In this way, the configuration of the light-emitting device 10 can be further simplified compared to the example of Fig. 8.

[0109] Fig. 13 shows another example of the configuration of the light-emitting device 10 according to the eighth embodiment. As in Fig. 7, Fig. 13 shows a light-emitting device 10 having three types of light-emitting elements: a first light-emitting element 1-1, a second light-emitting element 1-2, and a third light-emitting element 1-3. In Fig. 13, reference numeral 1310 schematically indicates the cross-sectional structure of the light-emitting device 10, and reference numeral 1320 schematically indicates the planar layout of the light-emitting device 10.

[0110] In the example of Fig. 13, the first bank BK1, the second bank BK2, and the third bank BK3 each contain a PL material MP that absorbs the third EL light and emits PL light, as in the example of Fig. 8. Therefore, in the example of Fig. 13, the first bank BK1, the second bank BK2, and the third bank BK3 each have the same height, as in the example of Fig. 8.

[0111] 13, unlike the example of FIG. 9, two adjacent banks BK do not form a valley portion VL between the two BK. Therefore, the light-emitting device 10 in the example of FIG. 13 does not need to have a conductive reflective film CR. In this way, the configuration of the light-emitting device 10 can be further simplified compared to the example of FIG. 9.

[0112] [Embodiment 9] Fig. 14 shows an example of the configuration of a light emitting device 10 according to embodiment 9. The light emitting device 10 in Fig. 14 is a variation of the light emitting device 10 in Fig. 12. In Fig. 14, reference numeral 1410 schematically indicates the cross-sectional structure of the light emitting device 10, and reference numeral 1420 schematically indicates the planar layout of the light emitting device 10.

[0113] The symbol SS1 in FIG. 14 indicates the slope of the first bank BK1 that slopes in the direction from the second EL layer E2 toward the first EL layer E1 (that is, in the negative direction of the X direction).

[0114] The light emitting device 10 in the example of Fig. 14 includes a conductive reflective film CRU, unlike the example of Fig. 12. As shown in Fig. 14, the conductive reflective film CRU may be located above the slope SS1. The conductive reflective film CRU can reduce the risk of color mixing caused by PL light in the light emitting device 10.

[0115] Fig. 15 shows another example of the configuration of the light emitting device 10 according to the ninth embodiment. The light emitting device 10 in Fig. 15 is a variation of the light emitting device 10 in Fig. 13. In Fig. 15, reference numeral 1510 schematically indicates the cross-sectional structure of the light emitting device 10, and reference numeral 1520 schematically indicates the planar layout of the light emitting device 10.

[0116] The symbol SS2 in FIG. 15 indicates the slope of the second bank BK2 that slopes in the direction from the third EL layer E3 toward the second EL layer E2 (that is, in the negative direction of the X direction).

[0117] The light emitting device 10 in the example of Fig. 15 also has a conductive reflective film CRU, similar to the example of Fig. 14. As shown in Fig. 15, the conductive reflective film CRU may be located above the slope SS2.

[0118] In the example of Fig. 15, the PL main peak wavelength is 470 nm. The first EL main peak wavelength is 630 nm, the second EL main peak wavelength is 530 nm, and the third EL main peak wavelength is 460 nm. Thus, in the example of Fig. 15, the PL main peak wavelength is longer than the third EL main peak wavelength and shorter than the second EL main peak wavelength and the first EL main peak wavelength.

[0119] As described above, when the PL main peak wavelength is longer than the third EL main peak wavelength and shorter than the second EL main peak wavelength and the first EL main peak wavelength, the PL material MP can be excited only by the third EL light. That is, the PL material MP can be prevented from being excited by either the first EL light or the second EL light. Therefore, as shown by reference numeral 1520, the light-emitting device 10 in the example of FIG. 15 does not need to have a conductive reflective film CRU between the first EL light-emitting layer E1 and the second EL light-emitting layer E2.

[0120] As shown by reference numeral 1520, in the light-emitting device 10, the first light-emitting element 1-1, the second light-emitting element 1-2, and the third light-emitting element 1-3 may be repeatedly arranged in this order in the X direction. Therefore, the light-emitting device 10 of FIG. 15 may have a third light-emitting element 1-3A in addition to the single third light-emitting element 1-3. In the example of reference numeral 1510, the third light-emitting element 1-3A is adjacent to the first light-emitting element 1-1 on the negative side in the X direction. In this way, the third light-emitting element 1-3A is adjacent to the first light-emitting element 1-1 on the side opposite to the second light-emitting element 1-2.

[0121] In the example of Fig. 15, the third bank of the third light-emitting element 1-3A is referred to as the third bank BK3A. The third EL light-emitting layer of the third light-emitting element 1-3A is referred to as the third EL light-emitting layer E3A. As is clear from Fig. 15, the first bank BK1 and the third bank BK3A are located between the first EL light-emitting layer E1 and the third EL light-emitting layer 3EA (not shown in the diagram of reference numeral 1510).

[0122] 15 indicates a slope of the first bank BK1 that slopes in the direction from the third EL light-emitting layer E3A toward the first EL light-emitting layer E1 (i.e., in the positive direction of the X direction). In the example of Fig. 15, the conductive reflective film CRU is also located above the slope SS1A.

[0123] 16 shows a configuration example of a display device 100 according to embodiment 10. The display device 100 may include a light-emitting device according to one aspect of the present disclosure (e.g., light-emitting device 10). Therefore, the display device 100 may include a light-emitting element according to one aspect of the present disclosure (e.g., light-emitting element 1).

[0124] The display device 100 may include a display unit DA including a plurality of subpixels SP, a first driver X1 and a second driver X2 that drive the plurality of subpixels SP, and a display control unit DC that controls the first driver X1 and the second driver X2. The subpixels SP may include a light-emitting element 1 and a pixel circuit PC connected to the light-emitting element 1. The display device 100 may include, as the light-emitting elements 1, a first light-emitting element 1-1, a second light-emitting element 1-2, and a third light-emitting element 1-3.

[0125] The pixel circuit PC may be connected to a scanning signal line GL, a data signal line DL, and an emission control line ELL. As an example, the scanning signal line GL and the emission control line ELL may be connected to a first driver X1. The data signal line DL may be connected to a second driver X2.

[0126] [Additional Notes] One aspect of 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 one aspect of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0127] 1 Light-emitting element 1-1 First light-emitting element 1-2 Second light-emitting element 1-3 Third light-emitting element 1-3A Another third light-emitting element 10 Light-emitting device 81 EL light 82 PL light 100 Display device UE Upper electrode UE1 First upper electrode UE2 Second upper electrode UE3 Third upper electrode LE Lower electrode LE1 First lower electrode LE2 Second lower electrode LE3 Third lower electrode E EL light-emitting layer E1 First EL light-emitting layer E2 Second EL light-emitting layer E3 Third EL light-emitting layer E3A Third EL light-emitting layer of another third light-emitting element ELA EL light-emitting region BK Bank BK1 First bank BK2 Second bank BK3 Third bank MP PL material MP1 First PL material MP2 Second PL material MP3 Third PL material MF Metal reflective film TF Light-transmitting film RF1 First light reflecting surface RF2 Second light reflecting surface SS Sloping surface of bank SS1 Sloping surface of first bank (sloping surface sloping in the direction from the second EL light emitting layer to the first EL light emitting layer) SS1A Sloping surface of second bank (sloping surface sloping in the direction from the third EL light emitting layer to the first EL light emitting layer of another third light emitting element) SS2 Sloping surface of second bank (sloping surface sloping in the direction from the third EL light emitting layer to the second EL light emitting layer) VL Valley portion CR Conductive reflective film (conductive reflective film located on the upper surface of the valley portion) CRU Conductive reflective film (conductive reflective film located on the upper side of the sloping surface of the bank)

Claims

1. An upper electrode and a lower electrode facing each other, an EL (Electro-Luminescence) light-emitting layer that receives carrier injection from the upper electrode and the lower electrode and emits EL light, and an insulating bank located on the side of the EL light-emitting layer, wherein at least one of the upper electrode and the lower electrode is a light-transmitting electrode, the bank contains a PL (Photo-Luminescence) material that emits PL light, and the main peak wavelength of the EL light is represented as λ ＥＬ＿ＰＥＡＫ and the main peak wavelength of the PL light is represented as λ ＰＬ＿ＰＥＡＫ , when the PL material absorbs light with a wavelength of λ ＥＬ＿ＰＥＡＫ and λ ＰＬ＿ＰＥＡＫ −30 nm ≤ λ ＥＬ＿ＰＥＡＫ ≤ λ ＰＬ＿ＰＥＡＫ +10 nm, a light-emitting device.

2. λ ＥＬ＿ＰＥＡＫ <λ ＰＬ＿ＰＥＡＫ The light-emitting element according to claim 1, wherein ＥＬ＿ＰＥＡＫ < λ ＰＬ＿ＰＥＡＫ .

3. The bank contains resin, and the content rate of the resin in the bank is 30% by weight or more. The light-emitting element according to claim 1 or 2.

4. The resin is a photocurable resin. The light-emitting element according to claim 3.

5. The thickness of the bank is 300 nm or more. The light-emitting element according to claim 3 or 4.

6. The bank contains QD (Quantum Dot) as the PL material. The light-emitting element according to any one of claims 1 to 5.

7. The EL light-emitting layer contains EL core-shell QD, the bank contains PL core-shell QD, the EL core-shell QD has an EL core as an EL material that emits the EL light and an EL shell that covers the EL core, the PL core-shell QD has a PL core as the PL material and a PL shell that covers the PL core, and the thickness of the PL shell is larger than the thickness of the EL shell. The light-emitting element according to claim 6.

8. The EL light has a single peak wavelength. The light-emitting element according to any one of claims 1 to 7.

9. The full width at half maximum in the emission spectrum of the EL light is 40 nm or less. The light-emitting element according to claim 8.

10. The content rate of the PL material in the bank is less than 50% by weight. The light-emitting element according to any one of claims 1 to 9.

11. At least a part of the bank is located below the lower electrode in the EL light-emitting region of the light-emitting element. The light-emitting element according to any one of claims 1 to 10.

12. It has a metal reflection film located above or below the bank and a light transmission film located between the bank and the metal reflection film. The light-emitting element according to any one of claims 1 to 11.

13. At least a part of the bank is sandwiched between a first light reflection surface and a second light reflection surface that are parallel to each other. The light-emitting element according to any one of claims 1 to 12.

14. In the region sandwiched between the first light reflection surface and the second light reflection surface, the PL light does not scatter. The light-emitting element according to claim 13.

15. In each part belonging to the region sandwiched between the first light reflection surface and the second light reflection surface, when observed on a scale longer than half the main peak wavelength of the PL light, the refractive index is constant. The light-emitting element according to claim 13 or 14.

16. When the radiance of the PL light forming an angle θ with respect to the normal direction of the horizontal plane of the substrate of the light-emitting element is denoted as RM(θ), there exist angles θ1 and θ2 satisfying RM(θ2) / RM(θ1) ≤ 0.7 at 0° ≤ θ1 < θ2 < 70°. The light-emitting element according to any one of claims 13 to 15.

17. The light-emitting element according to any one of claims 13 to 16, wherein the bank contains a mixture of QD and resin.

18. The light-emitting element according to any one of claims 13 to 17, wherein the first light-reflecting surface and the second light-reflecting surface enhance the main peak wavelength component of the PL light in the normal direction of the horizontal plane of the substrate of the light-emitting element.

19. The light-emitting element according to any one of claims 13 to 18, wherein the inclined surface of the bank is located between the first light-reflecting surface and the second light-reflecting surface.

20. The light-emitting element according to claim 19, wherein the bank contains a non-light-emitting portion inside, and the thickness of the non-light-emitting portion is larger than the thickness of the EL light-emitting layer.

21. The light-emitting element according to claim 20, wherein the surface of the non-light-emitting portion has light reflectivity.

22. The light-emitting element according to any one of claims 19 to 21, wherein the first light-reflecting surface and the second light-reflecting surface located so as to sandwich the inclined surface of the bank enhance the main peak wavelength component of the PL light in the normal direction of the horizontal plane of the substrate of the light-emitting element.

23. The light-emitting element according to any one of claims 13 to 22, wherein the distance between the first light-reflecting surface and the second light-reflecting surface is larger than 0 μm and 1 μm or less.

24. A light-emitting device having the light-emitting element according to any one of claims 1 to 23.

25. The light-emitting device includes, as a plurality of the light-emitting elements, a first light-emitting element and a second light-emitting element adjacent to the first light-emitting element. The first light-emitting element has, as the upper electrode and the lower electrode, a first upper electrode and a first lower electrode, respectively. The first light-emitting element has, as the EL light-emitting layer, a first EL light-emitting layer that receives carrier injection from the first upper electrode and the first lower electrode and emits first EL light. The first light-emitting element has, as the bank, a first bank located on the side of the first EL light-emitting layer. The second light-emitting element has, as the upper electrode and the lower electrode, a second upper electrode and a second lower electrode, respectively. The second light-emitting element has, as the EL light-emitting layer, a second EL light-emitting layer that receives carrier injection from the second upper electrode and the second lower electrode and emits second EL light. The second light-emitting element has, as the bank, a second bank located on the side of the first EL light-emitting layer. The first bank and the second bank are located between the first EL light-emitting layer and the second EL light-emitting layer. The main peak wavelength of the first EL light is longer than the main peak wavelength of the second EL light. The light-emitting device according to claim 24.

26. The first bank and the second bank form a valley portion between the first bank and the second bank. The light-emitting device has a conductive reflective film located on the upper surface of the valley portion. The light-emitting device according to claim 25.

27. The height of the first bank is the same as the height of the second bank. The light-emitting device according to claim 25 or 26.

28. The first bank contains a first PL material that absorbs the first EL light and emits first PL light. The second bank contains a second PL material that absorbs the second EL light and emits second PL light. The main peak wavelength of the first PL light is longer than the main peak wavelength of the second PL light. The height of the first bank is greater than the height of the second bank. The light-emitting device according to claim 25 or 26.

29. The first bank and the second bank each contain the PL material that absorbs the second EL light and emits the PL light. The main peak wavelength of the PL light is longer than the main peak wavelength of the second EL light and shorter than the main peak wavelength of the first EL light. The light-emitting device according to claim 25.

30. The first bank has an inclined surface that inclines along the direction from the second EL light-emitting layer toward the first EL light-emitting layer, and the light-emitting device has a conductive reflective film located above the inclined surface of the first bank. The light-emitting device according to claim 29.

31. The light-emitting device further has, as a plurality of the light-emitting elements, a third light-emitting element adjacent to the second light-emitting element on the side opposite to the first light-emitting element. The third light-emitting element has a third upper electrode and a third lower electrode as the upper electrode and the lower electrode, respectively, has a third EL light-emitting layer that emits third EL light by receiving carrier injection from the third upper electrode and the third lower electrode as the EL light-emitting layer, and has a third bank located on the side of the third EL light-emitting layer as the bank. The second bank and the third bank are located between the second EL light-emitting layer and the third EL light-emitting layer. The main peak wavelength of the second EL light is longer than the main peak wavelength of the third EL light. The first bank, the second bank, and the third bank each contain the PL material that absorbs the third EL light and emits the PL light. The main peak wavelength of the PL light is longer than the main peak wavelength of the third EL light and shorter than the main peak wavelength of the second EL light. The light-emitting device according to claim 25.

32. The second bank has an inclined surface that inclines along the direction from the third EL light-emitting layer toward the second EL light-emitting layer, and the light-emitting device has a conductive reflective film located above the inclined surface of the second bank. The light-emitting device according to claim 31.

33. The light-emitting device further has, as a plurality of the light-emitting elements, another third light-emitting element adjacent to the first light-emitting element on the side opposite to the second light-emitting element. The first bank and the third bank of the other third light-emitting element are located between the first EL light-emitting layer and the third EL light-emitting layer of the other third light-emitting element. The first bank has an inclined surface that inclines along the direction from the third EL light-emitting layer of the other third light-emitting element toward the first EL light-emitting layer, and the light-emitting device further has a conductive reflective film located above the inclined surface of the first bank. The light-emitting device according to claim 32. A display device comprising the light-emitting device according to any one of claims 24 to 33.

Images