Patent Application
20230284469
The present invention relates to a light-emitting element and a light-emitting device.
Patent Document 1 discloses a light-emitting device including: a light-emitting layer provided on a substrate; and a bank dividing the light-emitting layer on the substrate so that each of the divided light-emitting layers corresponds one of sub-pixels. Patent Document 1 discloses a configuration in which, on the bank, a reflective unit is provided in contact with an organic light-emitting layer.
However, Patent Document 1 described above has a problem; that is, of the light emitted from the light-emitting layer, some of the light propagates in an in-plane direction of a light-emitting surface of the light-emitting device. The propagating light is reflected in the organic light-emitting layer and on an interface of an electrode provided on the organic light-emitting layer, and fails to exit outside.
An object of the present disclosure is to provide a light-emitting element and a light-emitting device capable of effectively using light propagating in an in-plane direction of a light-emitting surface of the light-emitting device.
A light-emitting element according to an aspect of the present disclosure includes: a first light-emitting layer containing first quantum dots and configured to emit a first light including a first peak wavelength; a second light-emitting layer containing second quantum dots and configured to emit a second light including a second peak wavelength greater than the first peak wavelength; a substrate having a surface on which the first light-emitting layer and the second light-emitting layer are arranged side-by-side in a first direction; and a first bank provided on the substrate and dividing the first light-emitting layer from the second light-emitting layer, wherein the first bank is transparent to the first light traveling from the first light-emitting layer toward the second light-emitting layer.
Moreover, a light-emitting element according to an aspect of the present disclosure includes: a plurality of first light-emitting layers each containing first quantum dots and configured to emit a first light including a first peak wavelength; a substrate on which the plurality of first light-emitting layers are arranged in line; and a bank provided on the substrate and dividing two of the first light-emitting layers arranged side-by-side, wherein, between the two first light-emitting layers, the bank is transparent to the first light emitted from each of the two first light-emitting layers.
Furthermore, a light-emitting device according to an aspect of the present disclosure includes: a thin-film transistor; and the light-emitting element electrically connected to the thin-film transistor. This light-emitting element includes: a first light-emitting layer containing first quantum dots and configured to emit a first light including a first peak wavelength; a second light-emitting layer containing second quantum dots and configured to emit a second light including a second peak wavelength greater than the first peak wavelength; a substrate having a surface on which the first light-emitting layer and the second light-emitting layer are arranged side-by-side in a first direction; and a first bank provided on the substrate and dividing the first light-emitting layer from the second light-emitting layer, wherein the first bank is transparent to the first light traveling from the first light-emitting layer toward the second light-emitting layer.
Described below is an exemplary embodiment of the present disclosure, with reference to the drawings. Note that, hereinafter, the term “above” denotes a direction from an array substrate 2 (a substrate) toward a light-emitting element 3 of a light-emitting device 1, and the term “below” denotes the opposite direction of the term “above”. Moreover, like reference signs designate identical constituent features throughout the drawings. Such constituent features will not be repeatedly elaborated upon.
As illustrated in
The plurality of blue light-emitting layers 6B, the plurality of green light-emitting layers 6G, and the plurality of red light-emitting layers 6R are arranged on a surface of, and in an in-plane direction of, the array substrate 2. Thus, in the light-emitting device 1 according to the embodiment, the plurality of blue light-emitting layers 6B, green light-emitting layers 6G, and red light-emitting layers 6R form a light-emitting surface in parallel with the in-plane direction of the array substrate 2.
Specifically, in
Light-Emitting Device
Described below with reference to
The light-emitting element 3 includes: an anode 4; a hole-transport layer 5; a light-emitting layer 6; an electron-transport layer 7; and a cathode 8. In the light-emitting device 1 according to the embodiment, the anode 4, the hole-transport layer 5, the light-emitting layer 6, the electron-transport layer 7, and the cathode 8 are stacked on top of another in the stated order from below upward above the array substrate 2.
The anode 4 is formed on the array substrate 2, and electrically connected to a TFT of the array substrate 2. The anode 4 is a reflective substrate containing: a metal including Al, Cu, Au, or Ag highly reflective to visible light; and a transparent material including ITO, IZO, ZnO, AZO, or BZO. The metal and the transparent material are stacked on top of another above the array substrate 2. The anode 4 can be formed by, for example, sputtering or vapor deposition.
The hole-transport layer 5 transports holes injected from the anode 4 further into the light-emitting layer 6. The hole-transport layer 5 is formed on, and electrically connected to, the anode 4. Examples of the hole-transport layer 5 include an arylamine derivative, an anthracene derivative, a carbazole derivative, a thiophene derivative, a fluorene derivative, a distyrylbenzene derivative, a spiro compound, and metal oxide. The hole-transport layer 5 can be formed by such a technique as, for example, vapor deposition, printing, ink-jet printing, spin coating, casting, dipping, bar coating, blade coating, roll coating, gravure coating, flexographic printing, spray coating, photolithography, or self-assembly (layer-by-layer and self-assembled monolayer). Note that the hole-transport layer 5 may be formed of nanoparticles, crystals, polycrystals, or an amorphous solid.
Moreover, between the hole-transport layer 5 and the anode 4, a not-shown hole-injection layer may be provided to promote injection of the holes from the anode 4.
The light-emitting layer 6 is provided between the anode 4 and the cathode 8. More specifically, the light-emitting layer 6 is provided between the hole-transport layer 5 and the electron-transport layer 7. The light-emitting layer 6 contains quantum dots (semiconductor nanoparticles) in the form of one or more layers stacked on top of another. The light-emitting layer 6 can be formed of a fluid disperse containing such a solvent as hexane or toluene into which the quantum dots are dispersed. The light-emitting layer 6 can be formed by spin-coating or ink-jet printing. In the fluid disperse, such a dispersant as thiol or amine may be mixed.
The quantum dots, which have a valence band level and conduction band level, are a light-emitting material that emits light by recombination of the hole at the valence band level and the electrons at the conduction band level. The light emitted from the quantum dots has a narrow spectrum because of the quantum confinement effect, so that the emitted light can be relatively deep in chromaticity.
Each of the quantum dots is a semiconductor nanoparticle having a core/shell structure including: a core made of CdSe; and a shell made of ZnS. Other than that, the quantum dot may have such a core/shell structure as CdSe/CdS, InP/ZnS, ZnSe/Zn, or CIGS/ZnS. Moreover, the shell has an outer periphery portion to which a ligand is coordinated. The ligand is made of, for example, such an organic substance as thiol or amine.
The quantum dots have a particle size of approximately 3 nm to 15 nm. A wavelength of light emitted from the quantum dots can be controlled by the particle size of the quantum dots. Hence, by controlling the particle size of the quantum dots, a wavelength of light emitted from the light-emitting device 1 can be controlled.
The electron-transport layer 7 is provided on the light-emitting layer 6. The electron-transport layer 7 is a transparent conductive film to transport the electrons injected from the cathode 8 into the light-emitting layer 6. The electron-transport layer 7 may function to keep the holes from being transported to the cathode 8 (a hole-blocking function). Examples of the electron-transport layer 7 include: oxadiazoles, triazoles, phenanthrolines, a silole derivative, a cyclopentadiene derivative, an aluminum complex, and metal oxide. The electron-injection layer can be formed by such a technique as, for example, vapor deposition, printing, ink-jet printing, spin coating, casting, dipping, bar coating, blade coating, roll coating, gravure coating, flexographic printing, spray coating, photolithography, or self-assembly (layer-by-layer and self-assembled monolayer).
Moreover, between the electron-transport layer 7 and the cathode 8, a not-shown electron-injection layer may be provided to promote injection of the electrons from the cathode 8.
The cathode 8 is formed on, and electrically connected to, the electron-transport layer 7. The cathode 8 can be formed of either a thin metal film transparent to light, or a transparent material. Examples of the metal forming the cathode 8 include Al, Ag, and Mg. Moreover, examples of the transparent material forming the cathode 8 include ITO, IZO, ZnO, AZO, and BZO. The cathode 8 can be formed by, for example, sputtering or vapor deposition.
In the light-emitting device 1 having the above configuration, the holes injected from the anode 4 and the electrons injected from the cathode 8 are transported respectively through the hole-transport layer 5 and the electron-transport layer 7 to the light-emitting layer 6. Then, the holes and the electrons transported to the light-emitting layer 6 recombine together in quantum dots 61, and an exciton occurs. When the exciton transfers from an excited state back to a ground state, the quantum dots 61 emit light.
Note that
Furthermore, the light-emitting device 1 according to the embodiment includes: the anode 4; the hole-transport layer 5; the light-emitting layer 6; the electron-transport layer 7; and the cathode 8, all of which are stacked on top of another in the stated order from below upward above the array substrate 2. However, the light-emitting device 1 may also be of an inverted structure; that is, the light-emitting device 1 include: the cathode 8; the electron-transport layer 7; the light-emitting layer 6; the hole-transport layer 5; and the anode 4, all of which are stacked on top of another in the stated order from below upward above the array substrate 2.
The light-emitting device 1 according to the embodiment is provided with the bank 10 on the array substrate 2. The bank 10 divides each of the blue light-emitting layers 6B, each of the green light-emitting layers 6G, and each of the red light-emitting layers 6R. The bank 10 includes: a first bank region 11 (a first bank); a second bank region 12 (a second bank); and a third bank region 13. Each of the bank regions is described below.
First Bank Region
The first bank region 11 is a region to divide the light-emitting layers 6 arranged side-by-side above the array substrate 2 and emitting light in different peak wavelengths. Of the light rays emitted from each of the light-emitting layers 6 arranged side-by-side, the first bank region 11 is transparent to a light ray having a shorter peak wavelength (a first light), and non-transparent to a light ray having a longer peak wavelength (a second light).
In the light-emitting device 1 illustrated in
That is, the blue light L (B), which propagates in the in-plane direction of the light-emitting surface of the light-emitting element 3, is partially reflected because of a difference in refractive index on an interface between the cathode 8; that is, a transparent electrode provided above the blue light-emitting layer 6B, and a layer (i.e. air if no layer is formed) formed above the cathode 8. Hence, the reflected light is not released outside. Hence, as to the light-emitting device 1 according to the embodiment, the blue light L (B) not released outside is allowed to pass through the first bank region 11B and is propagated to the red light-emitting layer 6R and the green light-emitting layer 6G arranged next to the blue light-emitting layer 6B.
Here, the red light-emitting layer 6R absorbs light whose peak wavelength is equal to the peak wavelength of red or below, and the green light-emitting layer 6G absorbs light whose peak wavelength is equal to the peak wavelength of green or below. Hence, the light-emitting device 1 emits light by photoluminescence (PL).
Thus, the light-emitting device 1 allows the red light-emitting layer 6R and the green light-emitting layer 6G to: absorb the blue light L (B) emitted from the blue light-emitting layer 6B; and emit light. Thanks to such a feature, the light-emitting device 1 can reduce a voltage to be applied to the light-emitting layers 6 for emitting the red light L (R) and the green light L (G).
For example, a light-emitting device emits a blue light having a luminance of 1000 cd/m2 (0.9 μW/mm2). Moreover, the light-emitting device fails to emit outside the blue light propagating in the in-plane direction of the light-emitting surface. In other words, as to the light-emitting device, a rate of the blue light to be emitted outside is determined in accordance with a rate of light totally reflected on an interface between the light-emitting layer and a layer above the light-emitting layer. Because of such a configuration of the light-emitting device, 20% of the emitted blue light is released out of the light-emitting element 3, and 80% of the emitted blue light stays inside the light-emitting element 3. That is, the light having a luminance of 3.6 μW/mm2 stays inside the light-emitting element 3.
Here, the green light-emitting layer 6G next to the blue light-emitting layer 6B absorbs and emits the blue light L (B) that stays inside the light-emitting element 3. The light-emitting device 1 is expected to exhibit an advantageous effect of reducing a voltage by 0.1 V with respect to light emitted at a luminance of 5 μW/mm2. If an optical density of the first bank region 11B is 0, the voltage to be applied to the green light-emitting layer 6G to emit a green light can be reduced by 0.1 V.
Moreover, the reduced amount of the voltage depends on the optical density of the first bank region 11B. For example, if the optical density of the first bank region 11B is 1, the voltage to be applied can be reduced by 0.01 V. Moreover, if the optical density of the first bank region 11B is 2, the voltage to be applied can be reduced by 0.001 V.
Hence, preferably, the optical density of the first bank region 11B is, in particular, 1 or less. If the optical density of the first bank region 11B is 1 or less, the voltage can be reduced by 0.01 V or more. Such a feature makes it possible to effectively reduce the voltage of the light-emitting device 1.
Moreover, in order to reduce reflection on an interface between the first bank region 11B and the blue light-emitting layer 6B, a refractive index of the first bank region 11 is the same as, or close to, a refractive index of the blue light-emitting layer 6B. In particular, when the blue light L (B) is lost by the reflection on the interface between the first bank region 11B and the blue light-emitting layer 6B because of a difference in refractive index between the first bank region 11B and the blue light-emitting layer 6B, the rate of the loss is reduced to less than 1%. That is, a refractive index of the blue light-emitting layer 6B is nQD, and a refractive index of the first bank region 11B is n. Here, an expression (1) below represents a condition in which a reflectance (normal incidence) is less than 1% of light incident from the blue light-emitting layer 6B having the refractive index nQD to the first bank region 11B having the refractive index n.
(nQD−n)2/(nQD+n)2<0.01 (1)
Hence, the refractive index of the blue light-emitting layer 6B and the refractive index of the first bank region 11B are set to satisfy the relationship of an expression (2) below derived from the above expression (1).
n
QD×9/11<n<nQD×11/9 (2)
Second Bank Region
The second bank region 12 is a region to divide a plurality of light-emitting layers 6 arranged side-by-side and emitting light rays in the same peak wavelength and the same color. In the light-emitting device 1 illustrated in
Hence, the light-emitting device 1 according to the embodiment allows the blue light-emitting layers 6B to: absorb light having a wavelength shorter than the blue peak wavelength included in the blue light L (B) passing through the second bank region 12; and emit light by PL.
Moreover, in the light-emitting device 1 illustrated in
Hence, the light-emitting device 1 according to the embodiment allows the green light-emitting layers 6G to: absorb light having a wavelength shorter than the green peak wavelength included in the green light L (G) passing through the second bank region 12; and emit light by PL.
Moreover, in the light-emitting device 1 illustrated in
Thus, as to the light-emitting device 1 according to this embodiment, when light is emitted from the two neighboring blue light-emitting layers 6B, the two neighboring green light-emitting layers 6G, and the two neighboring red light-emitting layer 6R emit light, the light-emitting device 1 can reduce a voltage to be applied to each of the light-emitting layers 6.
Note that the second bank region 12 can be made of a transparent material transparent to light so that the light emitted from the two neighboring blue light-emitting layers 6B, the two neighboring green light-emitting layers 6G, and the two neighboring red light-emitting layers 6R can pass through the second bank region 12. This transparent material is preferably at least one resin selected from the group consisting of, for example, acrylic polymer, polysiloxane, and polyimide.
Third Bank Region
Moreover, the third bank region 13 is the remaining region except the first bank region 11 and the second bank region 12 described above. In the light-emitting device 1 according to the embodiment, the third bank region 13 is a region to divide a green light-emitting layer 6G from a red light-emitting layer 6R both of which are arranged side-by-side above the array substrate 2. Furthermore, the third bank region 13 is a region to surround a blue light-emitting layer 6B, the green light-emitting layer 6G, and the red light-emitting layer 6R along an outer periphery of the array substrate 2.
Of the light rays emitted from the green light-emitting layer 6G and the red light-emitting layer 6R, the third bank region 13 reflects outside, in particular, a light ray propagating in the in-plane direction of the light-emitting surface and kept from traveling outside. Specifically, the third bank region 13 has side faces each in contact with one of the green light-emitting layer 6G and the red light-emitting layer 6R. The side faces are angled in the vertical direction. That is, as illustrated in
As can be seen, the third bank region 13 reflects light propagating in the in-plane direction of the light-emitting surface so that the propagating light is released outside. Hence, the light-emitting device 1 can effectively use the light emitted from each of the green light-emitting layer 6G and the red light-emitting layer 6R.
Note that, in the above configuration, the blue light L (B) emitted from the blue light-emitting layer 6B is propagated through the first bank region 11B to each of: the green light-emitting layer 6G disposed next to the blue light-emitting layer 6B; and the red light-emitting layer 6R disposed next to the blue light-emitting layer. However, the light-emitting device 1 of the present disclosure shall not be limited to such a configuration. Alternatively, the light-emitting device 1 may be configured as follows. That is, the first bank region 11 may be a region provided between a green light-emitting layer 6G and a red light-emitting layer 6R arranged side-by-side. In such a case, the first bank region 11 is transparent to light whose peak wavelength is equal to a green peak wavelength or below. Note that, in the first bank region 11, a region transparent to light whose peak wavelength is equal to the green peak wavelength or below is referred to as a first bank region 11G. Then, the green light L (G) emitted from the green light-emitting layer 6G may be propagated through the first bank region 11G to the red light-emitting layer 6R next to the green light-emitting layer 6G.
As can be seen, in the light-emitting device 1, the first bank region 11B is transparent to light whose peak wavelength is equal to a blue peak wavelength or below. Here, in order to reduce color mixture due to stray light, the first bank region 11B preferably blocks the green light L (G) emitted from the green light-emitting layer 6G and the red light L (R) emitted from the red light-emitting layer 6R, so that neither of lights travels toward the blue light-emitting layer 6B through the first bank region 11B. Hence, in the light-emitting device 1 according to a first modification of the embodiment, the first bank region 11B is a blue color filter.
As can be seen, if the first bank region 11B is the blue color filter, the first bank region 11B can be transparent to the blue light L (B) emitted from the blue light-emitting layer 6B. Hence, the light-emitting device 1 according to the first modification can effectively allow the blue light L (B) to propagate to each of the green light-emitting layer 6G and the red light-emitting layer 6R. Furthermore, the first bank region 11B can absorb the green light L (G) and the red light L (R) traveling from the green light-emitting layer 6G and the red light-emitting layer 6R toward the blue light-emitting layer 6B. Hence, the light-emitting device 1 according to the first modification can keep the green light L (G) and the red light L (R) from entering the blue light-emitting layer 6B. Thus, the light-emitting device 1 according to the first modification can reduce color mixture due to stray light. Note that, if the first bank region 11 is the first bank region 11G, the first bank region 11G is a green color filter.
In the above light-emitting device 1 according to the embodiment, the third bank region 13 divides the green light-emitting layer 6G from the red light-emitting layer 6R both of which are arranged side-by-side. In contrast, in the light-emitting device 1 according to a second modification of the embodiment, the bank 10, which divides the green light-emitting layer 6G from the red light-emitting layer 6R both of which are arranged side-by-side, also serves as the first bank region 11 (the first bank region 11G).
Described below with reference to
As illustrated in
The light-emitting device 1 according to the second modification allows the green light-emitting layer 6G and the red light-emitting layer 6R to: absorb a blue light L (B) included in the blue lights L (B) emitted from the blue light-emitting layer 6B and propagating in the in-plane direction of the light emitting surface; and to emit light by photoluminescence (PL). Moreover, the light-emitting device 1 according to the second modification allows the red light-emitting layer 6R to: absorb a green light L (G) included in the green lights L (G) emitted from the green light-emitting layer 6G and propagating in the in-plane direction of the light-emitting surface; and to emit light by PL. Hence, the light-emitting device 1 can further reduce a voltage to be applied to the light-emitting layers 6.
Note that, in the light-emitting device 1 according to the second modification, the first bank region 11B may be a blue color filter, and the first bank region 11G may be a green color filter.
The light-emitting device 1 according to the above embodiment is configured in such a manner that, of the blue lights L (B) emitted from the blue light-emitting layer 6B, a blue light L (B) propagating in the in-plane direction of the light-emitting surface passes through the first bank region 11B and travels toward each of the green light-emitting layer 6G and the red light-emitting layer 6R both arranged next to the blue light-emitting layer 6B.
In such a configuration, when the blue light L (B) passes through the first bank region 11B and propagates to the green light-emitting layer 6G and the red light-emitting layer 6R, the blue light L (B) spreads out within, and travels through, the first bank region 11B. Hence, some of the blue light L (B) traveling in the in-plane direction of the light-emitting surface might not appropriately enter the green light-emitting layer 6G and the red light-emitting layer 6R.
Hence, in the light-emitting device 1 according to a third modification of the embodiment, an optical waveguide layer 22 is formed in the first bank region 11B to control a region in which the blue light L (B) can propagate.
Specifically, as illustrated in
The optical waveguide layer 22 can be formed in the first bank region 11B as follows. First, on the array substrate 2, a first resin layer 11B1 is stacked to form a base end portion of the first bank region 11B. On the stacked first resin layer 11B1, the optical waveguide layer 22 is stacked. Moreover, on the optical waveguide layer 22, a second resin layer 11B2 is stacked to form a distal end portion of the first bank region 11B. Hence, the first bank region 11B includes the first resin layer 11B1 and the second resin layer 11B2 stacked to hold the optical waveguide layer 22. Next, exposed portions of opposing end portions (horizontal end portions in
In the light-emitting device 1 according to the third modification of the embodiment, the blue light L (B) emitted from the blue light-emitting layer 6B is efficiently propagated through the optical waveguide layer 22 to the green light-emitting layer 6G and the red light-emitting layer 6R arranged next to the blue light-emitting layer 6B. Hence, in the light-emitting device 1 according to the third modification of the embodiment, the light-emitting layer 6 and the optical waveguide layer 22 are configured to satisfy the condition below.
That is, in order to form a waveguide mode in the blue light-emitting layer 6B, a refractive index of the blue light-emitting layer 6B is set greater than a refractive index of a first neighboring layer (the hole-transport layer 5 and the electron-transport layer 7) staked next to the blue light-emitting layer 6B. Specifically, the refractive index of the blue light-emitting layer 6B is set greater by 0.3% or more than the refractive index of each of the hole-transport layer 5 and the electron-transport layer 7 staked next to the blue light-emitting layer 6B. This set value (0.3% or more) is a value obtained as a refractive index difference required to allow the light to be totally reflected on an interface between the blue light-emitting layer 6B and the first neighboring layer (the hole-transport layer 5 and the electron-transport layer 7). Note that the waveguide mode here is a mode of the light propagating inside the optical waveguide 22 while the light is totally reflected on an interface between the optical waveguide 22 and a member (a layer) of the first bank region 11 surrounding the optical waveguide 22.
Moreover, when the blue light L (B) propagates in the in-plane direction of the light-emitting surface, the amount of the blue light L (B) confined in the blue light-emitting layer 6B depends on a thickness of the blue light-emitting layer 6B. Hence, as a condition to form the waveguide mode, a product of the thickness and the refractive index of the blue light-emitting layer 6B is set greater than a half wavelength of the emitted blue light L (B).
Moreover, in order to form the waveguide mode in the optical waveguide layer 22, the refractive index of the optical waveguide layer 22 is set greater in the first bank region 11B than a refractive index of a member surrounding an outer periphery of the optical waveguide layer 22. In this Description, the member to surround the outer periphery of the optical waveguide layer 22 includes the first resin layer 11B1, the second resin layer 11B2, and the cover portion 11B3 illustrated in
Furthermore, the optical waveguide layer 22 and the light-emitting layer 6 (the blue light-emitting layer 6B, the green light-emitting layer 6G, or the red light-emitting layer 6R) are provided so that a level difference between the upper faces of, and between the lower faces of, the layers is 0.3 nm or less. As can be seen, when the level difference of 0.3 nm or less is set between the optical waveguide layer 22 and the light-emitting layer 7, scattering of light is successfully prevented on the interface between the optical waveguide layer 22 and the light-emitting layer 6. Thus, the scattering of light is successfully prevented, thereby making it possible to reduce leakage of light and the resulting loss of the light to be absorbed into the light-emitting layer 6. Note that, in order to set the level difference to 0.3 nm or less between the optical waveguide layer 22 and the light-emitting layer 6, an exemplary processing to planarize the layers is either the plasma processing or the CMP processing.
Moreover, in order to reduce reflection of light on the interface between the optical waveguide layer 22 and the light-emitting layer 6, the optical waveguide layer 22 and the light-emitting layer 6 preferably have the same refractive index.
Furthermore, in the light-emitting device 1 according to the third modification of the embodiment, microtexturing is provided on the interface between the light-emitting layer 6 (for example, the blue light-emitting layer 6B in
In the light-emitting device 1 according to the above embodiment, the first bank region 11B is transparent to light whose peak wavelength is equal to the blue peak wavelength or below. Here, in view of reducing color mixture and loss of light, the first bank region 11B is particularly preferably transparent to light having a blue peak wavelength and reflective to other light.
Hence, in the light-emitting device 1 according to a fourth modification of the embodiment, as illustrated in
The dielectric multilayer film is a multilayer stack of optical thin films made of a plurality of dielectric materials having different refractive indexes. As to the dielectric multilayer film, the thicknesses and materials of the optical thin films are appropriately set so that the dielectric multilayer film can be transparent only to a light ray having a specific peak wavelength and reflective to light rays having other peak wavelengths. Hence, in the light-emitting device 1 according to the fourth modification, the dielectric multilayer film is reflective to the red light L (R) and the green light L (G), and transparent to the blue light L (B).
Specifically, the dielectric multilayer film included in the first bank region 11B according to the fourth modification is a multilayer stack including a combination of two or more layers including a high refractive index layer 31 (a first refractive index layer) and a low refractive index layer 32 (a second refractive index layer). That is, the multilayer film contains. TiO2 (a thickness of 185 nm) as the high refractive index layer 31; and MgF2 (a thickness of 295 nm) as the low refractive index layer 32. Then, the dielectric multilayer film is formed of the high refractive index layer 31 and the low refractive index layer 32 stacked together. In
Note that the above high refractive index layer 31 is formed of TiO2. However, the high refractive index layer 31 may be formed of Nb2O5 or Ta2O. Moreover, the above low refractive index layer 32 is formed of MgF2. However, the low refractive index layer 32 may be formed of SiO2 or Al2O3.
As can be seen, if the first bank region 11B is a dielectric multilayer film, the first bank region 11B is previously formed on a separate substrate by such a technique as the CVD. Then, the first bank region 11B formed on this separate substrate is stacked in an appropriate position on the array substrate 2 by reprinting or manipulation.
Note that the features of the above embodiment and modifications may appropriately be combined together.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/029728 | 8/4/2020 | WO |
