Image display device

Abstract

To provide an image display device capable of increasing luminance of wavelength-converted light emitted from a wavelength conversion layer.SOLUTION: An image display device comprises: a light emission layer which emits first color light; a wavelength conversion layer which converts a wavelength of the first color light into a wavelength of second color light regarding at least a part of the first color light emitted from the light emission layer; and a wavelength selective reflection layer through which the second color light emitted from the wavelength conversion layer is transmitted and, on the other hand, on which the first color light emitted from the wavelength conversion layer is reflected. The wavelength conversion layer contains quantum dots, which emit the second color light by absorbing at least a part of the first color light, and a transparent material holding the quantum dots and, on the other hand, does not contain particles larger than a particle diameter of the quantum dots.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an image display device.

Background Art

[0002] In recent years, as disclosed in Patent Document 1 below, development of image display devices has been carried out. Generally, an image display device includes a plurality of sub-pixels that constitute pixels. The sub-pixel includes a light-emitting layer and a wavelength conversion layer that converts the wavelength of the first color light emitted from the light-emitting layer to the wavelength of the second color light. As the light-emitting layer, for example, a blue light-emitting layer that emits blue light as the first color light can be considered. As the wavelength conversion layer, for example, a red wavelength conversion layer that emits red light as the second color light and a green wavelength conversion layer that emits green light as the second color light can be considered.

[0003] However, the red wavelength conversion layer cannot completely convert all of the blue light emitted from the light-emitting layer into red light, and the green wavelength conversion layer cannot completely convert all of the blue light emitted from the light-emitting layer into green light. That is, each of the red wavelength conversion layer and the green wavelength conversion layer transmits a part of the blue light emitted from the light-emitting layer. Therefore, the image display device includes, for example, a reflection layer that reflects a part of the blue light transmitted through each of the red wavelength conversion layer and the green wavelength conversion layer. This reflection layer functions to return a part of the blue light transmitted through the red wavelength conversion layer to the red wavelength conversion layer and a part of the blue light transmitted through the green wavelength conversion layer to the green wavelength conversion layer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the image display device disclosed in the above Patent Document 1, each of the red wavelength conversion layer and the green wavelength conversion layer contains particles that diffuse the blue light emitted from the light-emitting layer over a wider range than quantum dots. Therefore, the blue light emitted from the light-emitting layer is diffused within each of the red wavelength conversion layer and the green wavelength conversion layer. As a result, a part of the blue light transmitted through each of the red wavelength conversion layer and the green wavelength conversion layer is reflected so as to be dispersed by the reflection layer.

[0006] Therefore, it is difficult for a part of the blue light reflected by the reflection layer to return from the reflection layer to each of the red wavelength conversion layer and the green wavelength conversion layer. Therefore, the absorption efficiency of the blue light by each of the red wavelength conversion layer and the green wavelength conversion layer is low. Therefore, there is a possibility that the blue light as the first color light that has not been wavelength-converted is mixed with each of the red light and the green light as the wavelength-converted second color light transmitted through the reflection layer. As a result, the luminance of the wavelength-converted light emitted from the sub-pixel including the wavelength conversion layer cannot be increased.

[0007] As can be seen from the above, the luminance of the wavelength-converted light emitted from the sub-pixel including the wavelength conversion layer cannot be increased.

[0008] The present disclosure has been made in view of the above problems. An object of the present disclosure is to provide an image conversion device capable of increasing the luminance of the wavelength-converted light emitted from the wavelength conversion layer.

Means for Solving the Problems

[0009] The image display device of the present disclosure includes a light-emitting layer that emits first-color light, a wavelength conversion layer that converts the wavelength of at least a part of the first-color light emitted from the light-emitting layer to the wavelength of second-color light, and a wavelength-selective reflection layer that transmits the second-color light emitted from the wavelength conversion layer while reflecting the first-color light emitted from the wavelength conversion layer. The wavelength conversion layer contains quantum dots that emit the second-color light by absorbing at least a part of the first-color light and a transparent material that holds the quantum dots, and does not contain particles larger than the particle size of the quantum dots.

Brief Description of the Drawings

[0010]

Figure 1

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[0011] Hereinafter, the image display device according to the embodiment of the present disclosure will be described with reference to the drawings. Regarding the drawings, the same or equivalent elements are denoted by the same reference numerals, and duplicate explanations will not be repeated.

[0012] (Embodiment 1) The image display device 100 according to Embodiment 1 will be described with reference to FIGS. 1 to 9.

[0013] FIG. 1 is a cross-sectional view of each pixel PX constituting the image display device 100 of the present embodiment. FIGS. 2A, 2B, and 2C are schematic diagrams for explaining the configurations of the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B of the image display device 100 of the present embodiment, respectively.

[0014] As shown in FIG. 1, the image display device 100 includes a substrate 1, an electrode 2a, an electrode 2b, an electrode 2c, an insulating wall 3, a light-emitting layer 4, a red wavelength conversion layer 5R, a green wavelength conversion layer 5G, and a transparent layer 5B. The image display device 100 also includes a light-shielding wall 6RG, a light-shielding wall 6GB, a light-shielding wall 6BR, another transparent layer 7, an oxide film layer 8, a reflective layer 9, a red color filter 10R, and a green color filter 10G.

[0015] Each of the red wavelength conversion layer 5R and the green wavelength conversion layer 5G is an example of the wavelength conversion layer of the present disclosure. Each of the blue light emitted from the light-emitting layer 4 and the blue light emitted from the transparent layer 5B is an example of the first color in the present disclosure. Each of the red light emitted from the red wavelength conversion layer 5R and the green light emitted from the green wavelength conversion layer 5G is an example of the second color in the present disclosure. When the light-emitting layer 4 emits, for example, ultraviolet light as the first color light, the wavelength conversion layer of the present disclosure may convert the wavelength of the ultraviolet light into any of the wavelengths of red light, green light, or blue light as the second color light. Here, the blue light means a spectrum having a peak wavelength in the range of 400 nm to 500 nm. The green light means a spectrum having a peak wavelength in the range of 501 nm to 580 nm. The red light means a spectrum having a peak wavelength in the range of 581 nm to 700 nm.

[0016] The wavelength conversion layer of the present disclosure (for example, the red wavelength conversion layer 5R, the green wavelength conversion layer 5G) may be any one as long as it converts the wavelength of at least a part of the first color light emitted from the light-emitting layer 4 into the wavelength of the second color light. Note that the second color light has a longer wavelength than the first color light.

[0017] The substrate 1 includes a drive circuit (not shown) having a switching transistor or the like. The electrodes 2a, 2b, and 2c are electrically connected to the drive circuit within the substrate 1. The insulating wall 3 electrically insulates adjacent ones of the electrodes 2a, 2b, and 2c from each other. The electrodes 2a, 2b, and 2c may each have an anode or a cathode. Also, the electrodes 2a, 2b, and 2c each have an anode, and separately from this anode, may have a cathode in contact with the light-emitting layer 4.

[0018] In the present embodiment, the light-emitting layer 4 is a blue light-emitting layer including micro light-emitting diodes (Micro Light-Emitting Diodes) that emit blue light as the first color light. However, the light-emitting layer 4 of the present disclosure may emit light of any color such as ultraviolet light as long as it is a light-emitting layer that emits the aforementioned first color light. The light-emitting layer 4 is provided so as to cover the electrodes 2a, 2b, 2c, and the insulating wall 3. The light-emitting layer 4 has its light-emitting mode controlled by a drive circuit (not shown) within the substrate 1. The light-emitting layer 4 may be, for example, a multilayer film made of a nitride-based semiconductor.

[0019] The red wavelength conversion layer 5R is provided on the light-emitting layer 4 above the electrode 2a. The red wavelength conversion layer 5R wavelength-converts blue light as the first color light into red light as the second color light.

[0020] As shown in FIG. 2A, the red wavelength conversion layer 5R contains red quantum dots 5R-1 and a transparent material 5R-2. The red quantum dots 5R-1 emit red light as the second color light by absorbing at least a part of the blue light as the first color light. The transparent material 5R-2 holds the red quantum dots 5R-1. The transparent material is, for example, a transparent resin material. The red quantum dots 5R-1 may be, for example, a semiconductor made of InP as a material.

[0021] The red wavelength conversion layer 5R does not contain particles. In this specification, a particle is one that has a particle size larger than the particle size of the red quantum dots and diffuses blue light as the first color light over a wider range than the red quantum dots 5R-1. Note that the particle is a particle that does not convert at least the wavelength of blue light as the first color light to the wavelength of red light as the second color light. The particle size of the red quantum dots 5R-1 is larger than 0 nm and smaller than 100 nm. Note that the particle size of the particle is 100 nm or more.

[0022] In the present embodiment, the red wavelength conversion layer 5R consists essentially of only the red quantum dots 5R-1 and the transparent material 5R-2. In this specification, the term "essentially" allows that the red wavelength conversion layer 5R contains unavoidable impurities generated in the manufacturing process of the image display device 100 in addition to the red quantum dots 5R-1 and the transparent material 5R-2. In this specification, the term "essentially" means that it does not allow the inclusion of substances other than unavoidable impurities. However, the red wavelength conversion layer 5R of the present disclosure may be any as long as it does not contain the aforementioned particles.

[0023] The green wavelength conversion layer 5G is provided on the light-emitting layer 4 above the electrode 2b. The green wavelength conversion layer 5G is a quantum dot layer that converts blue light as the first color light to green light as the second color light.

[0024] As shown in FIG. 2B, the green wavelength conversion layer 5G contains green quantum dots 5G-1 and a transparent material 5G-2. The green quantum dots 5G-1 emit green light as the second color light by absorbing at least a part of blue light as the first color light. The transparent material 5G-2 holds the green quantum dots 5G-1. The transparent material 5G-2 is, for example, a transparent resin material. The green quantum dots 5G-1 may be, for example, a semiconductor made of InP as a material.

[0025] The green wavelength conversion layer 5G does not contain particles. In this specification, a particle is one that has a particle size larger than that of the green quantum dot 5G-1 and diffuses blue light as the first color light over a wider range than the green quantum dot 5G-1. This light-diffusing particle is a particle that does not convert at least the wavelength of blue light as the first color light to the wavelength of green light as the second color light. The particle size of the green quantum dot 5G-1 is larger than 0 nm and smaller than 100 nm. Note that the particle size of the light-diffusing particle is 100 nm or more.

[0026] In this embodiment, the green wavelength conversion layer 5G consists essentially of only the green quantum dot 5G-1 and the transparent material 5G-2. In this specification, the term "essentially" allows that the green wavelength conversion layer 5G contains unavoidable impurities generated in the manufacturing process of the image display device 100 in addition to the green quantum dot 5G-1 and the transparent material 5G-2. In this specification, the term "essentially" means not allowing the inclusion of substances other than unavoidable impurities. However, the green wavelength conversion layer 5G of the present disclosure may be any as long as it does not contain the aforementioned light-diffusing particles.

[0027] The transparent layer 5B is provided on the light-emitting layer 4 above the electrode 2c. The transparent layer 5B transmits blue light as the first color light emitted from the light-emitting layer 4. The transparent layer 5B does not contain particles. Note that the particle size of the particle is 100 nm or more. The transparent layer 5B may be, for example, a transparent resin material.

[0028] As shown in FIG. 2C, the transparent layer 5B consists essentially of only the transparent material 5B-2. Here, "essentially" means that the transparent layer 5B allows the inclusion of unavoidable impurities generated in the manufacturing process of the image display device 100, but does not allow the inclusion of substances other than unavoidable impurities. However, the transparent layer 5B of the present disclosure may be any as long as it does not contain the aforementioned light-diffusing particles.

[0029] The light-shielding wall 6RG is provided between the red wavelength conversion layer 5R and the green wavelength conversion layer 5G. The light-shielding wall 6RG suppresses the entry of light from the red wavelength conversion layer 5R into the green wavelength conversion layer 5G and also suppresses the entry of light from the green wavelength conversion layer 5G into the red wavelength conversion layer 5R. Therefore, the light-shielding wall 6RG can suppress the mixing of red light and green light in each of the red wavelength conversion layer 5R and the green wavelength conversion layer 5G. The light-shielding wall 6RG may be, for example, Al, Au, Cu, or Ag.

[0030] The light-shielding wall 6GB is provided between the green wavelength conversion layer 5G and the transparent layer 5B. The light-shielding wall 6GB suppresses the entry of light from the green wavelength conversion layer 5G into the transparent layer 5B and also suppresses the entry of light from the transparent layer 5B into the green wavelength conversion layer 5G. Therefore, the light-shielding wall 6GB can suppress the mixing of green light and blue light in each of the green wavelength conversion layer 5G and the transparent layer 5B. The light-shielding wall 6GB may be, for example, Al, Au, Cu, or Ag.

[0031] The light-shielding wall 6BR blocks the entry of light between the transparent layer 5B and the red wavelength conversion layer 5R. The light-shielding wall 6BR suppresses the entry of light from the transparent layer 5B into the red wavelength conversion layer 5R and also suppresses the entry of light from the red wavelength conversion layer 5R into the transparent layer 5B. Therefore, the light-shielding wall 6BR can suppress the mixing of blue light and red light in each of the transparent layer 5B and the red wavelength conversion layer 5R. The light-shielding wall 6BR may be, for example, Al, Au, Cu, or Ag.

[0032] The other transparent layer 7 transmits the red light emitted from the red wavelength conversion layer 5R, the green light emitted from the green wavelength conversion layer 5G, and the blue light emitted from the transparent layer 5B. The other transparent layer 7 is provided so as to cover each of the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B. The other transparent layer 7 may be, for example, a transparent resin material.

[0033] Generally, unevenness may exist on the light-emitting surfaces above the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B, respectively. Even in such a case, the surface on the light-emitting side above the other transparent layer 7 formed on each of the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B is flat. Therefore, if the oxide film layer 8 is formed on the other transparent layer 7, the oxide film layer 8 can be formed well.

[0034] The oxide film layer 8 transmits the red light emitted from the red wavelength conversion layer 5R, the green light emitted from the green wavelength conversion layer 5G, and the blue light emitted from the transparent layer 5B. The oxide film layer 8 is formed so as to cover the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B. Therefore, the oxide film layer 8 suppresses the oxidation of each of the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B. As a result, the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B can be protected. The oxide film layer 8 may be, for example, an oxide of Al or Zn.

[0035] The reflective layer 9 is provided at a position in the traveling direction of the red light emitted from the red wavelength conversion layer 5R and at a position in the traveling direction of the green light emitted from the green wavelength conversion layer 5G. However, the reflective layer 9 is not provided at a position in the traveling direction of the blue light emitted from the transparent layer 5B. Note that the traveling direction is a direction perpendicular to the two main surfaces of the substrate 1 facing each other. Therefore, the red wavelength conversion layer 5R and the green wavelength conversion layer 5G are covered by the reflective layer 9, but the transparent layer 5B is not covered by the reflective layer 9.

[0036] The reflective layer 9 is composed of a reflective material that transmits light in a specific wavelength range and reflects light with wavelengths outside the specific wavelength range. In the present embodiment, the reflective layer 9 reflects the blue light emitted from the transparent layer 5B, but transmits the red light emitted from the red wavelength conversion layer 5R and the green light emitted from the green wavelength conversion layer 5G. However, the reflective layer 9 may be any wavelength-selective reflective layer that transmits the second color light emitted from the wavelength conversion layer while reflecting the first color light emitted from the wavelength conversion layer. The reflective layer 9 may be, for example, a multilayer film in which Nb2O5 / SiO2 layers such as DBR (Distributed Bragg Reflection) are repeatedly laminated.

[0037] The red color filter 10R is provided at a position above the reflective layer 9 and in the traveling direction of the red light emitted from the red wavelength conversion layer 5R. The red color filter 10R mainly selectively transmits red light and absorbs light with wavelengths other than the wavelength of the red light. The green color filter 10G is provided at a position above the reflective layer 9 and in the traveling direction of the green light emitted from the green wavelength conversion layer 5G. The green color filter 10G mainly selectively transmits green light and absorbs light with wavelengths other than the wavelength of the green light. Each of the red color filter 10R and the green color filter 10G is an example of a second color light color filter that selectively transmits the second color light. The red color filter 10R and the green color filter 10G may be, for example, dioxazine-based pigments.

[0038] A color filter is not provided on the reflective layer 9 at a position in the traveling direction of the blue light emitted from the transparent layer 5B. That is, a first color light color filter that selectively transmits the first color light is not provided.

[0039] Each pixel PX of the image display device 100 includes a red sub-pixel SR, a green sub-pixel SG, and a blue sub-pixel SB. The red sub-pixel SR includes a part of the drive circuit of the substrate 1, the electrode 2a, a part of the light-emitting layer 4, the red wavelength conversion layer 5R, and the reflective layer 9.

[0040] The green sub-pixel SG includes a part of the driving circuit (not shown) of the substrate 1, the electrode 2b, a part of the light-emitting layer 4, the green wavelength conversion layer 5G, and the reflection distribution type reflection layer 9. The blue sub-pixel SB includes a part of the driving circuit of the substrate 1, the electrode 2c, a part of the light-emitting layer 4, and the transparent layer 5B, but does not have the reflection layer 9 above the transparent layer 5B.

[0041] FIG. 3A, FIG. 3B, and FIG. 3C are schematic diagrams for explaining the configurations of the red wavelength conversion layer 5R, the green wavelength conversion layer 5G, and the transparent layer 5B of the image display device EX of the comparative example, respectively.

[0042] As shown in FIG. 3A, the red wavelength conversion layer 5R of the image display device EX of the comparative example includes the aforementioned light diffusion particles DS in addition to the aforementioned red quantum dots 5R-1 and the transparent material 5R-2. As shown in FIG. 3B, the green wavelength conversion layer 5G of the image display device of the comparative example includes the aforementioned light diffusion particles DS in addition to the aforementioned green quantum dots 5G-1 and the transparent material 5G-2. As shown in FIG. 3C, the transparent layer 5B of the image display device of the comparative example includes the aforementioned particles DS in addition to the transparent material 5B-2.

[0043] FIG. 4A and FIG. 4B are the first and second diagrams for explaining the demerits when blue light is diffused in the red wavelength conversion layer 5R of each pixel of the image display device EX of the comparative example, respectively. The blue light emitted from the light-emitting layer 4 travels as shown by the solid arrows in FIG. 4A and then travels as shown by the solid arrows in FIG. 4B. In FIG. 4B, the dashed arrows indicate the light traveling paths before the current light traveling path indicated by the solid arrows.

[0044] According to the image display device EX of the comparative example shown in FIGS. 4A and 4B, the red wavelength conversion layer 5R contains light diffusion particles DS having a particle size of 100 nm or more (see FIG. 3A). Therefore, as shown by the solid arrows in FIG. 4B, blue light is diffused by the light diffusion particles DS inside the red wavelength conversion layer 5R. Therefore, the blue light emitted from the red wavelength conversion layer 5R is reflected so as to be dispersed by the reflection layer 9.

[0045] Therefore, the blue light emitted from the red wavelength conversion layer 5R is difficult to return only to the red wavelength conversion layer 5R. As a result, the ratio of the blue light as excitation light reused for wavelength conversion within the red wavelength conversion layer 5R is small. As a result, the luminance of the red light emitted from the red wavelength conversion layer 5R cannot be increased.

[0046] FIG. 5A and FIG. 5B are a first diagram and a second diagram, respectively, for explaining the merits when blue light is not diffused in the red wavelength conversion layer 5R of each pixel PX of the image display device 100 of the present embodiment. The blue light emitted from the light emitting layer 4 travels as indicated by the solid arrows in FIG. 5A and then travels as indicated by the solid arrows in FIG. 5B. In FIG. 5B, the dashed arrows indicate the light traveling path before the current light traveling path indicated by the solid arrows.

[0047] According to the image display device 100 of the present embodiment, the red wavelength conversion layer 5R does not contain light diffusing particles having a particle size of 100 nm or more (see FIG. 2A). Therefore, it becomes difficult for blue light to be diffused within the red wavelength conversion layer 5R. Thereby, the directivity of the blue light within the red wavelength conversion layer 5R is enhanced. That is, as shown in FIG. 5A, the blue light emitted from the light emitting layer 4 is likely to travel straight toward the reflection layer 9 via the red wavelength conversion layer 5R.

[0048] Therefore, as indicated by the solid arrows in FIG. 5B, the blue light emitted from the light-emitting layer 4 is reflected by the reflective layer 9 and is more likely to return into the red wavelength conversion layer 5R. As a result, the amount of blue light absorbed by the red quantum dots 5R-1 in the red wavelength conversion layer 5R increases. That is, the proportion of blue light as excitation light reused for wavelength conversion in the red wavelength conversion layer 5R increases. Therefore, the proportion of blue light mixed with the red light transmitted through the reflective layer 9 can be reduced. Accordingly, the luminance of the red light as the second color light wavelength-converted from the blue light as the first color light by the red wavelength conversion layer 5R can be increased. For the same reason as the increase in the luminance of the green wavelength conversion layer 5G, the luminance of the green light as the second color light wavelength-converted from the blue light as the first color light by the green wavelength conversion layer 5G can be increased.

[0049] FIG. 6 is a diagram for explaining the demerits when the blue light entering the transparent layer 5B from the light-emitting layer 4 below the green wavelength conversion layer 5G of each pixel PX of the image display device EX of the comparative example is diffused in the transparent layer 5B.

[0050] Further, in the image display device EX of the comparative example shown in FIG. 6, for example, the blue light emitted at a position below the green wavelength conversion layer 5G of the light-emitting layer 4 may travel toward the transparent layer 5B. In this case, it is diffused within the range of the capture angle by the particles DS (see FIG. 3C) of 100 nm or more in the transparent layer 5B. Therefore, crosstalk is likely to occur between the green sub-pixel SG emitting green light and the blue sub-pixel SB emitting blue light. This problem of crosstalk occurs between all adjacent sub-pixels.

[0051] FIG. 7 is a diagram for explaining the merits when the blue light entering the transparent layer 5B from the light-emitting layer 4 below the green wavelength conversion layer 5G of each pixel PX of the image display device 100 of the present embodiment is not diffused in the transparent layer 5B.

[0052] As shown in FIG. 7, in the image display device 100 of the present embodiment, the green wavelength conversion layer 5G does not contain particles (see FIG. 3B). Therefore, when the blue light emitted at a position below the green wavelength conversion layer 5G of the light emitting layer 4 travels toward the transparent layer 5B as indicated by the solid arrow in FIG. 7, it is not diffused within the capture angle range by some of the green quantum dots 5G-1 in the green wavelength conversion layer 5G. As a result, the blue light emitted at a position below the green wavelength conversion layer 5G of the light emitting layer 4 travels straight outside the capture angle range.

[0053] Thereby, crosstalk is less likely to occur between the green sub-pixel SG that emits green light and the blue sub-pixel SB that emits blue light. This crosstalk prevention effect is obtained not only in the relationship between the green sub-pixel SG and the blue sub-pixel SB, but also in the relationship between adjacent sub-pixels that emit light of all different colors.

[0054] FIG. 8 is a diagram for explaining the disadvantages when blue light is diffused in the transparent layer 5B of each pixel PX of the image display device EX of the comparative example.

[0055] According to the image display device 100 of the comparative example shown in FIG. 8, the transparent layer 5B contains particles DS having a particle diameter of 100 nm or more (see FIG. 3C). Thereby, as indicated by the solid arrow in FIG. 8, the blue light emitted from the light emitting layer 4 is diffused by the particles DS inside the transparent layer 5B, so that the luminance of the blue light traveling straight in the direction perpendicular to the substrate 1 from the transparent layer 5B cannot be increased.

[0056] FIG. 9 is a diagram for explaining the advantages when blue light is not diffused in the transparent layer 5B of each pixel PX of the image display device 100 of the present embodiment.

[0057] According to the image display device 100 of the present embodiment, the transparent layer 5B as the second wavelength conversion layer does not contain particles having a particle diameter of 100 nm or more (FIG. 2C). Therefore, it is difficult for the blue light as the first color light emitted from the light emitting layer 4 to be diffused in the transparent layer 5B. Thereby, the directivity of the blue light in the transparent layer 5B is enhanced. That is, as indicated by the solid line arrow in FIG. 9, the blue light emitted from the light emitting layer 4 is likely to be emitted in one direction from the transparent layer 5B. As a result, it is possible to increase the luminance of the blue light as the first color light that travels straight in the direction perpendicular to the substrate 1 from the transparent layer 5B constituting the blue sub-pixel SB.

[0058] Further, the reflective layer 9 is provided at a position deviated from the traveling direction of the blue light as the second color light emitted from the transparent layer 5B. Specifically, the reflective layer 9 is provided so as not to cover the transparent layer 5B. Therefore, since it is difficult for the blue light as the first color light to be reflected by the reflective layer 9, it is possible to increase the luminance of the blue light as the first color light constituting the blue sub-pixel SB.

[0059] (Embodiment 2) The image display device 100 of Embodiment 2 will be described with reference to FIG. 10. Note that the description of the points that are the same as those of the image display device 100 of Embodiment 1 will not be repeated below. The image display device 100 of the present embodiment is different from the image display device 100 of Embodiment 1 in the following points.

[0060] FIG. 10 is a cross-sectional view of each pixel PX constituting the image display device 100 of the present embodiment.

[0061] As shown in FIG. 10, the oxide film layer 8 provided in the image display device 100 of Embodiment 1 is not provided. In other words, the reflective layer 9 is provided directly on the red wavelength conversion layer 5R and the green wavelength conversion layer 5G. Even with such an image display device 100, the same effects as those obtained by the image display device 100 of Embodiment 1 can be obtained except for the effects obtained by the oxide film layer 8.

[0062] (Embodiment 3) Using FIG. 11, the image display device 100 of Embodiment 3 will be described. Note that descriptions of the points that are the same as those of the image display device 100 of Embodiment 1 or 2 will not be repeated below. The image display device 100 of the present embodiment is different from the image display device 100 of Embodiment 1 or 2 in the following points.

[0063] As shown in FIG. 11, in the image display device 100 of the present embodiment, in the configuration of the image display device 100 of Embodiment 1, other light shielding walls 61RG, 61GB, and 61BR are embedded above the light emitting layer 4. The other light shielding walls 61RG, 61GB, and 61BR are provided so as to be in contact with the light shielding walls 6RG, 6GB, and 6BR, respectively. Each of the other light shielding walls 61RG, 61GB, and 61BR suppresses crosstalk of blue light through the light emitting layer 4. Each of the other light shielding walls 61RG, 61GB, and 61BR does not necessarily completely separate adjacent sub-pixels (SR, SG, SB) from each other. Each of the other light shielding walls 61RG, 61GB, and 61BR may be, for example, a metal such as Au, Al, Ag, or Cu or a color filter that absorbs blue light.

[0064] (Embodiment 4) Using FIG. 12, the image display device 100 of Embodiment 4 will be described. Note that descriptions of the points that are the same as those of the image display device 100 of Embodiments 1 to 3 will not be repeated below. The image display device 100 of the present embodiment is different from the image display device 100 of Embodiments 1 to 3 in the following points.

[0065] As shown in FIG. 12, in the configuration of the image display device 100 of the present embodiment, other light shielding walls 62RG, 62GB, and 62BR are embedded in the light emitting layer 4 in the configuration of the image display device 100 of the first embodiment. The other light shielding walls 62RG, 62GB, and 62BR are in contact with the light shielding walls 6RG, 6GB, and 6BR, respectively, and are provided so as to be in contact with the light emitting layer 4. Each of the other light shielding walls 62RG, 62GB, and 62BR is also provided so as to be in contact with the insulating wall 3. Each of the other light shielding walls 62RG, 62GB, and 62BR suppresses crosstalk of blue light through the light emitting layer 4. Each of the other light shielding walls 62RG, 62GB, and 62BR is provided so as to completely separate the sub-pixels (SR, SG, SB) from each other. Each of the other light shielding walls 62RG, 62GB, and 62BR may be, for example, a metal such as Au, Al, Ag, or Cu, or a color filter that absorbs blue light.

[0066] (Embodiment 5) The image display device 100 of the fifth embodiment will be described with reference to FIG. 13. Note that descriptions of the same points as those of the image display devices 100 of the first to fourth embodiments will not be repeated below. The image display device 100 of the present embodiment is different from the image display devices 100 of the first to fourth embodiments in the following points.

[0067] As shown in FIG. 13, in addition to the configuration of the image display device 100 of the third embodiment, the image display device 100 of the present embodiment includes other light shielding walls 11RG, 11GB, and 11BR that are in contact with the end surfaces of the reflection layer 9 in the boundary regions between the sub-pixels (SR, SG, SB). Each of the other light shielding walls 11RG, 11GB, and 11BR is made of a material that shields blue light. The other light shielding walls 11RG, 11GB, and 11BR may or may not be provided. Each of the other light shielding walls 11RG, 11GB, and 11BR may be, for example, a color filter that absorbs blue light.

Description of Reference Numerals

[0068] 4 Light emitting layer 5R Red wavelength conversion layer 5R-1 Red Quantum Dot 5R-2 Transparent Material 5G Green Wavelength Conversion Layer 5G-1 Green Quantum Dot 5G-2 Transparent Material 5B Transparent Layer 6RG,6GB,6BR Light-Shielding Wall 7 Transparent Layer 8 Oxide Film Layer 9 Reflective Layer 10,11RG,11GB,11BR,62RG,62GB,62BR Other Light-Shielding Walls

Claims

1. A light-emitting layer that emits a first color light, A wavelength conversion layer that converts the wavelength of at least a part of the first color light emitted from the light-emitting layer into the wavelength of a second color light, A wavelength-selective reflective layer that transmits the second color light emitted from the wavelength conversion layer and reflects the first color light emitted from the wavelength conversion layer, and The wavelength conversion layer contains quantum dots that emit the second color light by absorbing at least a part of the first color light and a transparent material that holds the quantum dots, while does not contain particles larger than the particle size of the quantum dots, An image display device.

2. The wavelength conversion layer consists essentially of only the quantum dots and the transparent material, The image display device according to Claim 1.

3. The particle size of the quantum dots is smaller than 100 nm, and the particle size of the particles is 100 nm or more, The image display device according to Claim 1.

4. The particles do not convert the wavelength of the first color light into the wavelength of the second color light, The image display device according to Claim 1.

5. The second color light has a longer wavelength than the first color light, The image display device according to Claim 1.

6. The first color light is blue light having a peak wavelength in the range of 400 nm to 500 nm, the second color light is green light having a peak wavelength in the range of 501 nm to 580 nm, or red light having a peak wavelength in the range of 581 nm to 700 nm, The image display device according to Claim 5.

7. Further comprising a transparent layer that transmits the first color light emitted from the light-emitting layer, The transparent layer also does not contain the particles. The image display device according to claim 1.

8. The reflective layer is provided so as to cover the wavelength conversion layer but not to cover the transparent layer. The image display device according to claim 7.

9. The image display device further includes a light-shielding wall provided at least in either one of the space between the wavelength conversion layer and the transparent layer and the space between the wavelength conversion layer and another adjacent wavelength conversion layer. The image display device according to claim 7.

10. The image display device has another light-shielding wall in contact with each of the light-shielding wall and the light-emitting layer. The image display device according to claim 9.

11. The image display device further includes an oxide film layer provided so as to cover the wavelength conversion layer and the transparent layer. The image display device according to claim 7.

12. The image display device according to claim 11, further including another transparent layer between the wavelength conversion layer and the oxide film layer. The image display device according to claim 11.

Images