Display device

Abstract

A wavelength selection film (30) of a display device (1) has a transmittance spectrum having: a first transmittance maximum value (TMA1) in a first wavelength region (R1); a second transmittance maximum value (TMA2) in a second wavelength region (R2); a third transmittance maximum value (TMA3), which is larger than the first transmittance maximum value (TMA1) and the second transmittance maximum value (TMA2), in a third wavelength region (R3); a first transmittance minimum value (TMI1) in a wavelength region between the wavelength value corresponding to the first transmittance maximum value (TMA1) and the wavelength value corresponding to the second transmittance maximum value (TMA2); and a second transmittance minimum value (TMI2) in a wavelength region between the wavelength value corresponding to the second transmittance maximum value (TMA2) and the wavelength value corresponding to the third transmittance maximum value (TMA3). The wavelength value corresponding to the first transmittance minimum value (TMI1) is on the longer wavelength side as compared to a first light emission minimum wavelength (EMI1·EMI1'), and the wavelength value corresponding to the second transmittance minimum value (TMI2) is on the longer wavelength side as compared to the second light emission minimum wavelength (EMI2·EMI2').

Description

display device

[0001] The present disclosure relates to a display device including a light-emitting element having a cavity structure (also called a microcavity structure).

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

[0003] Patent Document 1 describes a method for reducing external light reflection by providing a wavelength-selective film containing a blend of multiple light-absorbing materials that absorb light of specific wavelengths on the display surface of a display device, instead of a circular polarizer that is provided on the display surface of the display device.

[0004] Japanese Patent Publication "JP 2014-132522"

[0005] In the field of display devices, research and development to further improve image quality has been actively conducted, and among these, technologies related to light-emitting elements having a cavity structure that can emit light with deeper chromaticity have attracted attention. However, in the case of light-emitting elements having a cavity structure, the emission peak wavelength when observed from an oblique direction may be relatively significantly shifted to the short wavelength side compared to the emission peak wavelength when observed from the front direction, resulting in a color change (e.g., appearing bluish). Furthermore, there is also the problem that the emission intensity when observed from an oblique direction for long-wavelength light, such as red light, is significantly lower than the emission intensity when observed from the front direction compared to blue or green light.

[0006] In the case of the wavelength selective film described in Patent Document 1, the problems specific to light emitting elements having the above-mentioned cavity structure are not taken into consideration at all, and therefore, when the wavelength selective film described in Patent Document 1 is applied to a display device including a light emitting element having a cavity structure, the above-mentioned problems of color change occurring when observed from an oblique direction and the problem of the radiation intensity of light on the long wavelength side becoming significantly lower cannot be avoided.

[0007] One aspect of the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a display device that can reduce external light reflection and can reduce the possibility of color changes and a significant decrease in the radiation intensity of light on the long wavelength side, even when a display device including a light-emitting element having a cavity structure is observed from an oblique direction.

[0008] In order to solve the above-mentioned problems, the display device of the present disclosure includes a light-emitting element including a first electrode, a second electrode, and a light-emitting layer provided between the first electrode and the second electrode, the first electrode and the second electrode forming a cavity structure; a display region in which a plurality of the light-emitting elements are provided; and a wavelength selection film provided above the plurality of light-emitting elements in the display region, wherein the plurality of light-emitting elements include a first light-emitting element having a first maximum emission wavelength in a first wavelength region, a second light-emitting element having a second maximum emission wavelength in a second wavelength region that is a region longer in wavelength than the first wavelength region, and a third light-emitting element having a third maximum emission wavelength in a third wavelength region that is a region longer in wavelength than the second wavelength region, a transmission spectrum of the wavelength selective film having a first transmittance maximum value in the first wavelength region, a second transmittance maximum value in the second wavelength region, a third transmittance maximum value in the third wavelength region that is greater than the first transmittance maximum value and the second transmittance maximum value, a first transmittance minimum value in a wavelength region between a wavelength value corresponding to the first transmittance maximum value and a wavelength value corresponding to the second transmittance maximum value, and a second transmittance minimum value in a wavelength region between a wavelength value corresponding to the second transmittance maximum value and a wavelength value corresponding to the third transmittance maximum value; and when the display region is displayed in white, an emission spectrum of white light from the display region before passing through the wavelength selective film has the first emission maximum wavelength, the second emission maximum wavelength, the third emission maximum wavelength, a first emission minimum wavelength in a wavelength region between the first emission maximum wavelength and the second emission maximum wavelength, and a second emission minimum wavelength in a wavelength region between the second emission maximum wavelength and the third emission maximum wavelength; The wavelength value corresponding to the first transmittance minimum value is on the longer wavelength side than the first emission minimum wavelength, and the wavelength value corresponding to the second transmittance minimum value is on the longer wavelength side than the second emission minimum wavelength.

[0009] One aspect of the present disclosure can provide a display device that can reduce external light reflection and can reduce the possibility of color change and a significant decrease in the radiation intensity of light on the long wavelength side, even when a display device including a light-emitting element having a cavity structure is observed from an oblique direction.

[0010] 5 is a plan view showing a schematic configuration of a display device of embodiment 1. FIG. 6 is a cross-sectional view showing a schematic configuration of a display region of the display device of embodiment 1. FIG. 7 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in the display device of embodiment 1. FIG. 8 is a diagram for explaining advantages and disadvantages of a cavity structure provided in the red light-emitting element shown in FIG. 3. FIG. 9 is a diagram showing transmission spectra of a wavelength selective film provided in the display device of embodiment 1 when observed from the front direction (θ=0°) and from an oblique direction (θ=45°). FIG. 10 is a diagram showing a transmission spectrum of a wavelength selective film provided in the display device of embodiment 1 shown in FIG. 5 when observed from the front direction (θ=0°) and from an oblique direction (θ=45°) of white light from the display region before passing through the wavelength selective film in the display device of embodiment 1 (when the display region is observed from the front direction (θ=0°) and from an oblique direction (θ=45°)). FIG. 11 is a diagram showing emission spectra of white light from the display region after passing through the wavelength selective film provided in the display device of embodiment 1 when the display surface is observed from the front direction (θ=0°) and from an oblique direction (θ=45°). 11A and 11B are diagrams illustrating the emission spectra of white light from the display region when the display surface shown in FIG. 7 is observed from the front (θ=0°) and from an oblique direction (θ=45°), normalized by the maximum radiation intensity value of blue light.

[0033] FIG. 11B is a cross-sectional view illustrating the schematic configuration of a display region of another display device of embodiment 1.

[0034] FIG. 11C is a cross-sectional view illustrating the schematic configuration of a display region of a display device of comparative example 1.

[0035] FIG. 11D is a diagram illustrating the emission spectra of white light from the display region when the display surface shown in FIG. 11 is observed from the front (θ=0°) and from an oblique direction (θ=45°), normalized by the maximum radiation intensity value of blue light.

[0036] FIG. 11C is a cross-sectional view illustrating the schematic configuration of a display region of a display device of comparative example 2.

[0037] FIG. 11D is a diagram illustrating the transmission spectra of a wavelength selective film provided in the display device of comparative example 2 when observed from the front (θ=0°) and from an oblique direction (θ=45°), respectively.18 is a diagram showing the emission spectrum of white light from the display region when the display surface of the display device of Comparative Example 2 is observed from the front direction (θ=0°) and from an oblique direction (θ=45°). It is a diagram showing the emission spectrum of white light from the display region when the display surface shown in FIG. 15 is observed from the front direction (θ=0°) and from an oblique direction (θ=45°), respectively, normalized by the maximum radiant intensity value of blue light. It is a diagram showing the optical characteristics of the display device of Comparative Example 1, the optical characteristics and characteristics of the wavelength selective film of the display device of Comparative Example 2, and the optical characteristics and characteristics of the wavelength selective film of the display device of Embodiment 1. It is a cross-sectional view showing a schematic configuration of the display region of the display device of Embodiment 2. It is a diagram showing the transmission spectrum of the wavelength selective film provided in the display device of Embodiment 2 shown in FIG. 18 when observed from the front direction (θ=0°), and the emission spectrum of white light from the display region of the display device of Embodiment 2 before passing through the wavelength selective film (when the display region is observed from the front direction (θ=0°) and from an oblique direction (θ=45°)). It is a cross-sectional view showing a schematic configuration of the display region of the display device of Comparative Example 3. 1 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device of Comparative Example 4. FIG. 2 is a diagram showing optical characteristics of a display device of Comparative Example 3, optical characteristics and characteristics of a wavelength selective film of a display device of Comparative Example 4, and optical characteristics and characteristics of a wavelength selective film of a display device of Embodiment 2.

[0011] The following describes embodiments of the present disclosure with reference to Figures 1 to 22. For the sake of convenience, components having the same functions as those described in specific embodiments will be denoted by the same reference numerals, and descriptions thereof may be omitted.

[0012] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0013] As shown in Fig. 1, the display device 1 includes a frame area NDA and a display area DA. The display area DA of the display device 1 includes a plurality of pixels PIX, each of which includes a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP. In this embodiment, a case in which one pixel PIX is configured with a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP will be described as an example, but this is not limiting. For example, one pixel PIX may include subpixels of other colors in addition to the red subpixel RSP, the green subpixel GSP, and the blue subpixel BSP.

[0014] FIG. 2 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1 of the first embodiment.

[0015] As shown in Figure 2, in the display area DA of the display device 1, a barrier layer 3, a thin film transistor layer 4 including a transistor TR, a red light-emitting element 5R, a green light-emitting element 5G, a blue light-emitting element 5B and a bank 23, a sealing layer 6, and a wavelength selection film 30 are provided on a substrate 12 in this order from the substrate 12 side.

[0016] The red subpixel RSP provided in the display area DA of the display device 1 includes a red light-emitting element 5R (third light-emitting element), the green subpixel GSP provided in the display area DA of the display device 1 includes a green light-emitting element 5G (second light-emitting element), and the blue subpixel BSP provided in the display area DA of the display device 1 includes a blue light-emitting element 5B (first light-emitting element). The red light-emitting element 5R included in the red subpixel RSP includes a first electrode 22, a functional layer 24R including a red light-emitting layer (third light-emitting layer), and a second electrode 25. The green light-emitting element 5G included in the green subpixel GSP includes the first electrode 22, a functional layer 24G including a green light-emitting layer (second light-emitting layer), and a second electrode 25. The blue light-emitting element 5B included in the blue subpixel BSP includes the first electrode 22, a functional layer 24B including a blue light-emitting layer (first light-emitting layer), and a second electrode 25. A cavity structure is formed by the first electrode 22 and the second electrode 25 of each of the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B, so that in the red light-emitting element 5R, light having a wavelength corresponding to the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24R including the red light-emitting layer, resonates and is stimulated to radiate; in the green light-emitting element 5G, light having a wavelength corresponding to the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24G including the green light-emitting layer, resonates and is stimulated to radiate; and in the blue light-emitting element 5B, light having a wavelength corresponding to the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24B including the blue light-emitting layer, resonates and is stimulated to radiate. In Figure 2, the functional layer 24R including a red light-emitting layer, the functional layer 24G including a green light-emitting layer, and the functional layer 24B including a blue light-emitting layer are shown to have approximately the same thickness, but strictly speaking, for the reasons described above, the functional layer 24G including a green light-emitting layer is thicker than the functional layer 24B including a blue light-emitting layer, and the functional layer 24R including a red light-emitting layer is thicker than the functional layer 24G including a green light-emitting layer.

[0017] The substrate 12 may be, for example, a resin substrate made of a resin material such as polyimide, or a glass substrate. In this embodiment, since the display device 1 is a flexible display device, a case where a resin substrate made of a resin material such as polyimide is used as the substrate 12 will be described as an example, but this is not limiting. If the display device 1 is a non-flexible display device, a glass substrate can be used as the substrate 12.

[0018] The barrier layer 3 is a layer that prevents foreign substances such as water and oxygen from penetrating into the transistor TR, the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B, and can be composed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these, formed by the CVD method.

[0019] The transistor TR portion of the thin film transistor layer 4 including the transistor TR includes the semiconductor film SEM and doped semiconductor films SEM′ and SEM″, an inorganic insulating film 16, a gate electrode G, an inorganic insulating film 18, an inorganic insulating film 20, a source electrode S and a drain electrode D, and a planarization film 21, and the portion of the thin film transistor layer 4 including the transistor TR other than the transistor TR portion includes the inorganic insulating film 16, the inorganic insulating film 18, the inorganic insulating film 20, and the planarization film 21.

[0020] The semiconductor films SEM, SEM', and SEM'' may be made of, for example, low-temperature polysilicon (LTPS) or an oxide semiconductor (for example, an In-Ga-Zn-O based semiconductor). In this embodiment, the case where the transistor TR has a top-gate structure will be described as an example, but the present invention is not limited to this, and the transistor TR may also have a bottom-gate structure.

[0021] The gate electrode G and the source electrode S and drain electrode D can be formed of a single layer or a multilayer film of a metal containing at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper, for example.

[0022] The inorganic insulating films 16, 18 and 20 can be formed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these films, which are formed by the CVD method.

[0023] The planarizing film 21 can be made of a coatable organic material such as polyimide or acrylic.

[0024] The red light-emitting element 5R includes a first electrode 22 above the planarization film 21, a functional layer 24R including a red light-emitting layer, and a second electrode 25. The green light-emitting element 5G includes a first electrode 22 above the planarization film 21, a functional layer 24G including a green light-emitting layer, and a second electrode 25. The blue light-emitting element 5B includes a first electrode 22 above the planarization film 21, a functional layer 24B including a blue light-emitting layer, and a second electrode 25. The insulating bank 23 covering the edge of the first electrode 22 can be formed by applying an organic material such as polyimide or acrylic and then patterning it by photolithography.

[0025] The sealing layer 6 is a light-transmitting film, and can be composed of, for example, an inorganic sealing film 26 that covers the second electrode 25, an organic film 27 that is above the inorganic sealing film 26, and an inorganic sealing film 28 that is above the organic film 27. The sealing layer 6 prevents foreign substances such as water and oxygen from penetrating into the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B.

[0026] The inorganic sealing films 26 and 28 are each an inorganic film, and may be formed, for example, by a CVD method using a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film thereof. The organic film 27 is a light-transmitting organic film with a planarizing effect, and may be formed, for example, using a coatable organic material such as acrylic. The organic film 27 may also be formed, for example, by an inkjet method. In this embodiment, the sealing layer 6 is formed of two inorganic films and one organic film disposed between the two inorganic films. However, the stacking order of the two inorganic films and one organic film is not limited to this. Furthermore, the sealing layer 6 may be formed solely of an inorganic film, solely of an organic film, one inorganic film and two organic films, or two or more inorganic films and two or more organic films.

[0027] The wavelength selective film 30 may be provided above the red light emitting element 5R, the green light emitting element 5G, and the blue light emitting element 5B. In the display device 1 according to the present embodiment, an example in which the wavelength selective film 30 is provided on the sealing layer 6, that is, a case in which the sealing layer 6 is provided between the red light emitting element 5R, the green light emitting element 5G, and the blue light emitting element 5B and the wavelength selective film 30, is described as an example, but the position in which the wavelength selective film 30 is provided is not limited to this.

[0028] 9 is a cross-sectional view showing a schematic configuration of a display area DA of another display device 1′ of embodiment 1. As shown in FIG. 9 , a functional film 40 having at least one of a touch sensor function, a protective function, and an anti-reflection function may be further provided directly above the wavelength selective film 30OC. In this case, the wavelength selective film 30OC may include, for example, a transparent adhesive (Optical Clear Adhesive) OCA for adhering to the functional film 40.

[0029] FIG. 3 is a cross-sectional view showing a schematic configuration of the red light emitting element 5R provided in the display device 1 of the first embodiment.

[0030] 3 , the functional layer 24R including the red light-emitting layer 23EM provided in the red light-emitting element 5R can be formed by stacking, for example, a hole injection layer 23HI, a hole transport layer 23HT, a red light-emitting layer 23EM, an electron transport layer 23ET, and an electron injection layer 23EI in this order from the first electrode 22 (anode). The hole injection layer 23HI, the hole transport layer 23HT, the electron transport layer 23ET, and the electron injection layer 23EI are charge functional layers in which holes or electrons, which are electric charges, can move within the layers. The red light-emitting element 5R has a cavity structure MC formed by the first electrode 22, the functional layer 24R including the red light-emitting layer 23EM, and the second electrode 25. In the red light-emitting element 5R, light having a wavelength corresponding to the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24R including the red light-emitting layer, resonates and emits induced light. Therefore, as long as the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24R including the red light-emitting layer, can be appropriately adjusted so that red light resonates and undergoes stimulated emission, one or more layers other than the red light-emitting layer 23EM may be omitted from the functional layer 24R including the red light-emitting layer 23EM. The red light-emitting layer 23EM may be, for example, an organic light-emitting layer or a light-emitting layer including quantum dots. The first electrodes 22 are formed in island shapes for each of the red subpixels RSP, green subpixels GSP, and blue subpixels BSP (see FIG. 2 ). The first electrodes 22 are formed by stacking, for example, ITO (indium tin oxide) and a metal layer including Ag, and have light reflectivity. On the other hand, the second electrode 25 is formed as a solid layer common to the red subpixel RSP, green subpixel GSP, and blue subpixel BSP (see FIG. 2 ), and is a semi-transparent electrode containing a light-transmitting conductive material such as MgAg, Ag, Yb (yttrium), ITO (indium tin oxide), IZO (indium zinc oxide), etc. That is, the second electrode 25 transmits part of the light and reflects part of the light.Note that, although the red light-emitting element 5R provided in the display device 1 has been described as an example here, the green light-emitting element 5G and the blue light-emitting element 5B provided in the display device 1 are similar to the red light-emitting element 5R described above, and in the green light-emitting element 5G, as long as the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24G including the green light-emitting layer, can be appropriately adjusted so that green light resonates and undergoes stimulated emission, one or more layers other than the green light-emitting layer in the functional layer 24G including the green light-emitting layer may be appropriately omitted, and in the blue light-emitting element 5B, as long as the distance between the first electrode 22 and the second electrode 25, i.e., the thickness of the functional layer 24B including the blue light-emitting layer, can be appropriately adjusted so that blue light resonates and undergoes stimulated emission, one or more layers other than the blue light-emitting layer in the functional layer 24B including the blue light-emitting layer may be appropriately omitted. In the display device 1 of this embodiment, the red light-emitting layer 23EM provided in the red light-emitting element 5R, the green light-emitting layer provided in the green light-emitting element 5G, and the blue light-emitting layer provided in the blue light-emitting element 5B are described as organic light-emitting layers as an example, but this is not limited to this, and the red light-emitting layer 23EM provided in the red light-emitting element 5R, the green light-emitting layer provided in the green light-emitting element 5G, and the blue light-emitting layer provided in the blue light-emitting element 5B may be light-emitting layers containing quantum dots, for example.

[0031] Fig. 4 is a diagram for explaining the advantages and disadvantages of the cavity structure MC provided in the red light-emitting element 5R shown in Fig. 3. For simplicity, Fig. 4 does not show components other than the first electrode 22, the red light-emitting layer 23EM, and the second electrode 25.

[0032] 4, the cavity structure MC provided in the red light-emitting element 5R causes light emitted from the red light-emitting layer 23EM to repeatedly reflect between the first electrode 22 and the second electrode 25, causing light having a wavelength corresponding to the distance between the first electrode 22 and the second electrode 25 to resonate and undergo stimulated emission. This has the advantage of reducing the half-width of the spectrum of light emitted from the red subpixel RSP of the display device 1, allowing light with deep chromaticity to be emitted. Note that, because such an advantage is obtained by having the cavity structure MC, the same advantage can also be obtained in each of the green light-emitting element 5G and the blue light-emitting element 5B.

[0033] 4 illustrates optical paths L1, L2, and L3 of the light emitted from the red light-emitting layer 23EM and resonated by the cavity structure MC. Optical path L1 indicates the optical path of light that is emitted from the red light-emitting layer 23EM, reflected by the first electrode 22, and then travels toward the display surface. Optical path L2 indicates the optical path of light that is emitted from the red light-emitting layer 23EM and travels toward the display surface without being reflected by either the first electrode 22 or the second electrode 25. Optical path L3 indicates the optical path of light that is emitted from the red light-emitting layer 23EM, reflected by the second electrode 25 and the first electrode 22 in this order, and then travels toward the display surface. The difference in optical distance between optical path L1 and optical path L2 is defined as D1, and the difference in optical distance between optical path L2 and optical path L3 is defined as D2. Here, the optical distance D in each layer is expressed by D = Σdi·ni·cosθi (Equation 1), where θi is the angle of transmitted light in the i-th transmission layer, di is the thickness of the i-th transmission layer, and ni is the refractive index of the i-th transmission layer. The wavelength of light emitted from the red light-emitting layer 23EM is λ, and m is an integer greater than or equal to 0. The condition for constructive interference between light traveling along optical paths L1 and L2, taking into account the phase rotation of reflection at the first electrode 22, is expressed as D1 = ((2m+1) / 4)λ (Equation 2). Furthermore, the condition for constructive interference between light traveling along optical paths L2 and L3, taking into account the phase rotation of reflection at the first electrode 22, is expressed as D2 = ((m+1) / 2)λ (Equation 3). When the emission angle of light on the display surface is θ, the angle θ is proportional to the reflection angle and emission angle at each layer. Therefore, from the relationship between Equation 1, Equation 2, and Equation 3, the wavelength of the resonating light is proportional to cos θ. Therefore, the light resonated by the cavity structure MC has the disadvantage that the wavelength of the resonating light becomes shorter as θ increases from 0° to 90°. Note that, since this disadvantage arises from having the cavity structure MC, the same disadvantage also arises in each of the green light-emitting element 5G and the blue light-emitting element 5B, although to different degrees.

[0034] Fig. 10 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1a of Comparative Example 1. Fig. 11 is a diagram showing the emission spectrum of white light from the display area DA when the display surface DM of the display device 1a of Comparative Example 1 is observed from the front (θ=0°) and from an oblique direction (θ=45°). Fig. 12 is a diagram showing the emission spectrum of white light from the display area DA when the display surface DM shown in Fig. 11 is observed from the front (θ=0°) and from an oblique direction (θ=45°), respectively, normalized by the maximum radiant intensity value of blue light.

[0035] The display device 1a of Comparative Example 1 shown in Fig. 10 differs from the display device 1 of Embodiment 1 described above with reference to Fig. 2 only in that it does not include the wavelength selection film 30. In the display device 1a of Comparative Example 1 not including the wavelength selection film 30, the phenomenon that the wavelength of the resonating light becomes shorter as θ increases from 0° to 90°, which is one of the disadvantages of the light emitting element having the cavity structure MC described above, can be confirmed, and as shown in Fig. 11, compared to the peak wavelength value of the red light when the display surface DM of the display device 1a of Comparative Example 1 is observed from the front direction (θ = 0°), the peak wavelength value of the red light when the display surface DM of the display device 1a of Comparative Example 1 is observed from an oblique direction (θ = 45°), is shifted relatively significantly to the short wavelength side, It can be seen that, compared to the peak wavelength value of green light when the display surface DM of the display device 1a is observed from the front (θ = 0°), the peak wavelength value of green light when the display surface DM of the display device 1a of Comparative Example 1 is observed from an oblique direction (θ = 45°) shifts relatively significantly toward the shorter wavelength side, and that, compared to the peak wavelength value of blue light when the display surface DM of the display device 1a of Comparative Example 1 is observed from an oblique direction (θ = 45°) shifts relatively slightly toward the shorter wavelength side.

[0036] The inventors of the present disclosure have also found that light-emitting elements having a cavity structure MC also have the following disadvantage. The display device 1a of Comparative Example 1, which includes a red light-emitting element 5R, a green light-emitting element 5G, and a blue light-emitting element 5B having a cavity structure MC, has a problem in that the radiation intensity of long-wavelength light, e.g., red light, when the display surface DM of the display device 1a of Comparative Example 1 is observed from an oblique angle (θ=45°) is significantly lower than the radiation intensity of long-wavelength light, e.g., red light, when the display surface DM of the display device 1a of Comparative Example 1 is observed from the front (θ=0°). As shown in FIG. 12 , the relative radiation intensity at the peak wavelength of red light when the display surface DM of the display device 1a of Comparative Example 1 is observed from an oblique angle (θ=45°) is approximately half the relative radiation intensity at the peak wavelength of blue light when the display surface DM of the display device 1a of Comparative Example 1 is observed from an oblique angle (θ=45°).

[0037] As described above, in the case of the display device 1a of Comparative Example 1, when the display surface is observed from an oblique direction, the problems of color change and the radiation intensity of light on the long wavelength side becoming significantly lower cannot be avoided.

[0038] Therefore, the inventors of the present disclosure have realized a display device 1 that can reduce external light reflection and reduce the possibility of color changes and a significant decrease in the radiation intensity of light on the long wavelength side, even when the display surface is observed from an oblique direction, by providing a wavelength selection film 30 having the optical properties described below in a layer above the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B, which have a cavity structure MC.

[0039] 5 is a diagram showing the transmission spectrum of the wavelength selective film 30 provided in the display device 1 of embodiment 1 when observed from the front direction (θ=0°) and from an oblique direction (θ=45°). FIG. 6 is a diagram showing the transmission spectrum of the wavelength selective film 30 provided in the display device 1 of embodiment 1 shown in FIG. 5 when observed from the front direction (θ=0°), and the emission spectrum of white light from the display area DA in the display device 1 of embodiment 1 before passing through the wavelength selective film 30 (when the display area DA is observed from the front direction (θ=0°) and from an oblique direction (θ=45°)). FIG. 7 is a diagram showing the emission spectrum of white light from the display area DA after passing through the wavelength selective film 30 provided in the display device 1 of embodiment 1 when the display surface DM is observed from the front direction (θ=0°) and from an oblique direction (θ=45°). 8 is a diagram showing the emission spectrum of white light from the display area DA when the display surface DM shown in FIG. 7 is observed from the front (θ=0°) and from an oblique angle (θ=45°), normalized by the maximum radiant intensity value of blue light. Here, the maximum emission wavelength means the wavelength value at which the relative radiant intensity is maximum in a specific wavelength range, the minimum emission wavelength means the wavelength value at which the relative radiant intensity is minimum in a specific wavelength range, the maximum transmittance value means the maximum value of transmittance in a specific wavelength range, and the minimum transmittance value means the minimum value of transmittance in a specific wavelength range.

[0040] As shown in Fig. 2, the display device 1 includes a red light-emitting element 5R, a green light-emitting element 5G, and a blue light-emitting element 5B. As shown in Fig. 6, the blue light-emitting element 5B has first emission maximum wavelengths EMA1 and EMA1' in a first wavelength region R1, the green light-emitting element 5G has second emission maximum wavelengths EMA2 and EMA2' in a second wavelength region R2, and the blue light-emitting element 5R has third emission maximum wavelengths EMA3 and EMA3' in a third wavelength region R3. In this embodiment, the first wavelength region R1 is a wavelength region of 400 nm or more and less than 500 nm, the second wavelength region R2 is a wavelength region of 500 nm or more and less than 600 nm, and the third wavelength region R3 is a wavelength region of 600 nm or more and less than 700 nm, but the present invention is not limited to this. 6 , in the emission spectrum of white light from the display area DA before passing through the wavelength selective film 30, when the display area DA is observed from an oblique direction (θ=45°), the second emission maximum wavelength EMA2′ and the third emission maximum wavelength EMA3′ are each shifted relatively significantly toward lower wavelengths compared to the second emission maximum wavelength EMA2 and the third emission maximum wavelength EMA3 when the display area DA is observed from the front direction (θ=0°). Furthermore, when the display area DA is observed from an oblique direction (θ=45°), the relative radiance at the third emission maximum wavelength EMA3′ is significantly lower than the relative radiance at the third emission maximum wavelength EMA3 when the display area DA is observed from the front direction (θ=0°).

[0041] As shown in Figure 5, the transmission spectrum of the wavelength selective film 30 provided in the display device 1 has first transmittance maximum values ​​TMA1 and TMA1' in the first wavelength region R1, second transmittance maximum values ​​TMA2 and TMA2' in the second wavelength region R2, third transmittance maximum values ​​TMA3 and TMA3' that are larger than the first transmittance maximum values ​​TMA1 and TMA1' and the second transmittance maximum values ​​TMA2 and TMA2' in the third wavelength region R3, first transmittance minimum values ​​TMI1 and TMI1' in the wavelength region between the wavelength values ​​corresponding to the first transmittance maximum values ​​TMA1 and TMA1' and the wavelength values ​​corresponding to the second transmittance maximum values ​​TMA2 and TMA2', and second transmittance minimum values ​​TMI2 and TMI2' in the wavelength region between the wavelength values ​​corresponding to the second transmittance maximum values ​​TMA2 and TMA2' and the wavelength values ​​corresponding to the third transmittance maximum values ​​TMA3 and TMA3'.

[0042] As shown in Figure 6, when the display area DA of the display device 1 is displayed in white, the emission spectrum of white light from the display area DA before passing through the wavelength selection film 30 has first emission maximum wavelengths EMA1 and EMA1', second emission maximum wavelengths EMA2 and EMA2', third emission maximum wavelengths EMA3 and EMA3', first emission minimum wavelengths EMI1 and EMI1' in the wavelength region between the first emission maximum wavelengths EMA1 and EMA1' and the second emission maximum wavelengths EMA2 and EMA2', and second emission minimum wavelengths EMI2 and EMI2' in the wavelength region between the second emission maximum wavelengths EMA2 and EMA2' and the third emission maximum wavelengths EMA3 and EMA3'.

[0043] As shown in Figure 6, the wavelength value corresponding to the first transmittance minimum value TMI1 of the wavelength selection film 30 is on the longer wavelength side than the first emission minimum wavelengths EMI1 and EMI1', and the wavelength value corresponding to the second transmittance minimum value TMI2 of the wavelength selection film 30 is on the longer wavelength side than the second emission minimum wavelengths EMI2 and EMI2'. Note that Figure 6 only shows the transmission spectrum when the wavelength selective film 30 is observed from the front (θ = 0°), and does not show the transmission spectrum when the wavelength selective film 30 is observed from an oblique direction (θ = 45°). However, as will be explained below, the optical characteristics of the wavelength selective film 30 do not depend greatly on the observation angle θ, so the wavelength value corresponding to the first transmittance minimum value TMI1' of the wavelength selective film 30 shown in Figure 5 is on the longer wavelength side than the first emission minimum wavelengths EMI1 and EMI1', and the wavelength value corresponding to the second transmittance minimum value TMI2' of the wavelength selective film 30 shown in Figure 5 is on the longer wavelength side than the second emission minimum wavelengths EMI2 and EMI2'. As shown in FIG. 5, the first transmittance maximum value TMA1 is slightly larger than the first transmittance maximum value TMA1′, but the wavelength value corresponding to the first transmittance maximum value TMA1 and the wavelength value corresponding to the first transmittance maximum value TMA1′ are approximately the same. The first transmittance minimum value TMI1 is slightly larger than the first transmittance minimum value TMI1′, but the wavelength value corresponding to the first transmittance minimum value TMI1 and the wavelength value corresponding to the first transmittance minimum value TMI1′ are approximately the same. The second transmittance maximum value TMA2 is slightly larger than the second transmittance maximum value TMA2′. The second transmittance minimum value TMI2 has a value slightly larger than the second transmittance minimum value TMI2', but the wavelength value corresponding to the second transmittance minimum value TMI2 and the wavelength value corresponding to the second transmittance minimum value TMI2' are substantially the same, the third transmittance maximum value TMA3 and the third transmittance maximum value TMA3' are substantially the same, and the wavelength value corresponding to the third transmittance maximum value TMA3 and the wavelength value corresponding to the third transmittance maximum value TMA3' are substantially the same.

[0044] As described above, the wavelength values ​​corresponding to the first transmittance minimum values ​​TMI1 and TMI1' of the wavelength selection film 30 are on the longer wavelength side than the first emission minimum wavelengths EMI1 and EMI1' which are in the wavelength region between the first emission maximum wavelengths EMA1 and EMA1' and the second emission maximum wavelengths EMA2 and EMA2'. Therefore, as shown in FIG. 6, the wavelength selection film 30 absorbs a greater amount of light on the shorter wavelength side than the peak of the emission spectrum in the second wavelength region R2 including the second emission maximum wavelength EMA2.

[0045] Furthermore, as described above, the wavelength values ​​corresponding to the second transmittance minimum values ​​TMI2 and TMI2' of the wavelength selective film 30 are on the longer wavelength side than the second emission minimum wavelengths EMI2 and EMI2' which are in the wavelength region between the second emission maximum wavelengths EMA2 and EMA2' and the third emission maximum wavelengths EMA3 and EMA3'. Therefore, as shown in FIG. 6, the wavelength selective film 30 absorbs a greater amount of light on the shorter wavelength side than the peak of the emission spectrum in the third wavelength region R3 including the third emission maximum wavelength EMA3.

[0046] Furthermore, as described above, the wavelength selective film 30 has the third transmittance maximum values ​​TMA3 and TMA3' which are greater than the first transmittance maximum values ​​TMA1 and TMA1' and the second transmittance maximum values ​​TMA2 and TMA2', as shown in FIG. 5, and therefore, as shown in FIG. 6, the amount of light absorbed in the emission spectrum of the third wavelength region R3 which includes the third emission maximum wavelength EMA3' can be reduced.

[0047] Therefore, as shown in Figures 7 and 8, the display device 1 equipped with the wavelength selective film 30 can suppress a relatively large shift in the peak wavelength of red light when the display surface DM of the display device 1 is observed from an oblique angle (θ = 45°) toward shorter wavelengths compared to the peak wavelength of red light when the display surface DM of the display device 1 is observed from the front (θ = 0°). Furthermore, the peak wavelength of green light when the display surface DM of the display device 1 is observed from an oblique angle (θ = 45°) can suppress a relatively large shift in the peak wavelength of green light when the display surface DM of the display device 1 is observed from the front (θ = 0°). This reduces the possibility of color shifts occurring even when the display device 1 is observed from an oblique angle. Furthermore, as shown in Figures 7 and 8, the display device 1 equipped with the wavelength selective film 30 can reduce the possibility of a significant decrease in the radiation intensity of light on the long-wavelength side when the display device 1 is observed from an oblique angle. Furthermore, the display device 1 equipped with the wavelength selective film 30 can reduce external light reflection.

[0048] In this embodiment, in order to reduce the possibility of color shifts to the shorter wavelength side when the display device 1 is observed from an oblique direction, an example will be described in which a wavelength selection film 30 is used in which the wavelength value corresponding to the second transmittance maximum value TMA2 is on the longer wavelength side than the second emission maximum wavelengths EMA2 and EMA2', and the wavelength value corresponding to the third transmittance maximum value TMA3 is on the longer wavelength side than the third emission maximum wavelengths EMA3 and EMA3', as shown in Figure 6. However, as described above, the present invention is not limited to this, as long as the wavelength values ​​corresponding to the first transmittance minimum values ​​TMI1 and TMI1' of the wavelength selection film 30 are on the longer wavelength side than the first emission minimum wavelengths EMI1 and EMI1', and the wavelength values ​​corresponding to the second transmittance minimum values ​​TMI2 and TMI2' of the wavelength selection film 30 are on the longer wavelength side than the second emission minimum wavelengths EMI2 and EMI2'.

[0049] Furthermore, in this embodiment, in order to suppress color changes due to a shift of the emission spectrum of the first wavelength region R1 to the short wavelength side that may occur when the display device 1 is observed from an oblique direction, an example will be described in which a wavelength selection film 30 is used in which the wavelength value corresponding to the first transmittance maximum value TMA1 is on the long wavelength side of the first emission maximum wavelengths EMA1 and EMA1', as shown in Figure 6, but the present invention is not limited to this.

[0050] FIG. 13 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1b of Comparative Example 2. FIG. 14 is a diagram showing the transmission spectra of the wavelength selective film 30′ provided in the display device 1b of Comparative Example 2 when observed from the front (θ=0°) and from an oblique direction (θ=45°). FIG. 15 is a diagram showing the emission spectra of white light from the display area when the display surface DM of the display device 1b of Comparative Example 2 is observed from the front (θ=0°) and from an oblique direction (θ=45°). FIG. 16 is a diagram showing the emission spectra of white light from the display area DA when the display surface DM shown in FIG. 15 is observed from the front (θ=0°) and from an oblique direction (θ=45°), normalized by the maximum radiant intensity value of blue light. FIG. 17 is a diagram showing the optical characteristics of the display device 1a of Comparative Example 1, the optical characteristics and characteristics of the wavelength selective film 30′ of the display device 1b of Comparative Example 2, and the optical characteristics and characteristics of the wavelength selective film 30 of the display device 1 of Embodiment 1.

[0051] The display device 1b of Comparative Example 2 shown in Figure 13 differs from the display device 1 of Embodiment 1 described above with reference to Figure 2 only in that it includes a wavelength selective film 30'. As shown in Figure 14, in the case of the wavelength selective film 30', unlike the case of the wavelength selective film 30 shown in Figure 5, the third transmittance maximum values ​​TMA3 and TMA3' are greater than the second transmittance maximum values ​​TMA2 and TMA2' but smaller than the first transmittance maximum values ​​TMA1 and TMA1'. Therefore, in the case of the display device 1b of Comparative Example 2 including the wavelength selective film 30', as shown in Figures 15 and 16, the problem that the radiant intensity when observed from an oblique direction is significantly lower for long-wavelength light, for example, red light, than for blue light or green light, when observed from a frontal direction cannot be improved.

[0052] 14 and 17, in the case of the wavelength selective film 30′, unlike the wavelength selective film 30 shown in FIGS. 5 and 6, the wavelength value (497 nm) corresponding to the first transmittance minimum value TMI1 is on the shorter wavelength side compared to the wavelength value (506 nm) corresponding to the first transmittance minimum value TMI1 of the wavelength selective film 30, and is the same wavelength as the first emission minimum wavelength EMI1 (497 nm) shown in FIG. 6, and the wavelength value (593 nm) corresponding to the second transmittance minimum value TMI2 is on the shorter wavelength side compared to the wavelength value (599 nm) corresponding to the second transmittance minimum value TMI2 of the wavelength selective film 30, and is the same wavelength as the second emission minimum wavelength EMI2 (593 nm) shown in FIG. Therefore, in the case of the display device 1b of Comparative Example 2 which includes the wavelength selective film 30', the optical characteristic related to the coloring when viewed from an oblique angle (Δu'v' (θ=45°)) deteriorates from 0.017 to 0.037, compared to the display device 1 of Embodiment 1 which includes the wavelength selective film 30. When the emission spectra at θ=45° (oblique) of the display device 1a of Comparative Example 1 shown in FIG. 12 and the display device 1b of Comparative Example 2 shown in FIG. 16 are compared, it is found that the amount of decrease in the relative radiation intensity in the green light region and the amount of decrease in the relative radiation intensity in the red light region with respect to the relative radiation intensity in the blue light region normalized to 1 is larger in the case of the display device 1b of Comparative Example 2 shown in FIG. 16 than in the case of the display device 1a of Comparative Example 1 shown in FIG. Therefore, in the case of display device 1b of comparative example 2 shown in Figure 16, the relative radiation intensity of the green light region and the relative radiation intensity of the red light region are smaller than the relative radiation intensity of the blue light region normalized to 1, so the display appears bluer, and the optical characteristic (0.037) for the oblique coloring (Δu'v' (θ = 45°)) of display device 1b of comparative example 2 shown in Figure 16 is greater than the optical characteristic (0.020) for the oblique coloring (Δu'v' (θ = 45°)) of display device 1a of comparative example 1 shown in Figure 12.

[0053] In order to improve the optical characteristics related to oblique coloring (Δu'v' (θ=45°)), it is preferable that the wavelength selection film 30 has a wavelength value corresponding to the first transmittance minimum value TMI1 in the wavelength range of 500 nm or more and 520 nm or less, and a wavelength value corresponding to the second transmittance minimum value TMI2 in the wavelength range of 595 nm or more and 610 nm or less. As shown in Figures 6 and 17, the wavelength selection film 30 provided in the display device 1 of this embodiment has a wavelength value (506 nm) corresponding to the first transmittance minimum value TMI1 that is longer than the first emission minimum wavelength EMI1 (497 nm) shown in Figure 6, and a wavelength value (599 nm) corresponding to the second transmittance minimum value TMI2 that is longer than the second emission minimum wavelength EMI2 (593 nm) shown in Figure 6, so there is no deterioration in optical characteristics related to oblique coloring (Δu'v' (θ = 45°)) as with the wavelength selection film 30' described above.

[0054] Furthermore, in terms of improving the optical characteristics related to oblique coloring (Δu'v' (θ=45°)), it is preferable that the transmission spectrum of the wavelength selective film 30 has a first full width at half maximum HW1, which is the width of the first valley having its bottom at the first transmittance minimum value (TMI1) in the transmittance calculated by ((first transmittance maximum value TMA1 + first transmittance minimum value TMI1) / 2), of 30 nm or more and 40 nm or less, and a second full width at half maximum HW2, which is the width of the second valley having its bottom at the second transmittance minimum value (TMI2) in the transmittance calculated by ((second transmittance maximum value TMA2 + second transmittance minimum value TMI2) / 2), of 30 nm or more and 40 nm or less, as shown in Figures 5 and 17. As shown in FIG. 17, the wavelength selection film 30 provided in the display device 1 of this embodiment has a first full width at half maximum HW1 of 39 nm and a second full width at half maximum HW2 of 33 nm, and therefore does not suffer from deterioration in optical characteristics related to oblique coloring (Δu'v' (θ=45°)) as seen in the above-mentioned wavelength selection film 30′ having a first full width at half maximum HW1 of 48 nm and a second full width at half maximum HW2 of 67 nm.

[0055] The wavelength selection film 30 provided in the display device 1 of this embodiment has a wavelength value corresponding to the first transmittance minimum value TMI1, a wavelength value corresponding to the second transmittance minimum value TMI2, a first full width at half maximum HW1, and a second full width at half maximum HW2, which are preferable in terms of improving the optical characteristics related to oblique coloring (Δu'v' (θ=45°)).Therefore, as shown in Figure 17, a display device 1 can be realized in which the optical characteristics related to oblique coloring (Δu'v' (θ=45°)) are significantly improved to 0.017 compared to the display device 1a of Comparative Example 1 and the display device 1b of Comparative Example 2.

[0056] Furthermore, in the wavelength selection film 30 provided in the display device 1 of this embodiment, the third transmittance maximum values ​​TMA3 and TMA3' are larger than the first transmittance maximum values ​​TMA1 and TMA1' and the second transmittance maximum values ​​TMA2 and TMA2', so a display device 1 can be realized with a high transmittance of 67.9%, compared to the transmittance (53.3%) of the display device 1b of comparison example 2.

[0057] Furthermore, by providing the wavelength selective film 30, the reflectance is 24.2%, which is lower than the reflectance (51.3%) of the display device 1a of Comparative Example 1, and a display device 1 that can reduce external light reflection can be realized.

[0058] In the wavelength selective film 30 provided in the display device 1, the second transmittance maximum values ​​TMA2 and TMA2' are preferably larger than the first transmittance maximum values ​​TMA1 and TMA1'. In this embodiment, as shown in Figure 5, a case will be described as an example in which the second transmittance maximum values ​​TMA2 and TMA2' are slightly larger than the first transmittance maximum values ​​TMA1 and TMA1', but the present invention is not limited to this. The second transmittance maximum values ​​TMA2 and TMA2' may be significantly larger than the first transmittance maximum values ​​TMA1 and TMA1' as long as they are smaller than the third transmittance maximum values ​​TMA3 and TMA3'. In this case, a display device can be realized that can reduce the possibility that the radiation intensity of light on the longer wavelength side, for example, green light, when observed from an oblique direction will be significantly lower than the radiation intensity when observed from the front direction, compared to blue light.

[0059] The wavelength selective film 30 included in the display device 1 can be formed, for example, by dissolving a visible light absorbing material capable of selectively absorbing light in a specific wavelength range in the visible light range (400 nm to 750 nm) in a solvent to produce a coating solution, then applying the coating solution to a predetermined film and removing the solvent. Furthermore, when the wavelength selective film 30OC includes a transparent adhesive OCA, as in the wavelength selective film 30OC shown in FIG. 9 , the transparent adhesive OCA can be mixed into the coating solution, for example. In this embodiment, the visible light absorbing material used is, for example, a mixture of appropriate amounts of FDG-001 (maximum absorption wavelength: 503 nm), FDG-002 (maximum absorption wavelength: 525 nm), FDG-007 (maximum absorption wavelength: 594 nm), and FDR-001 (maximum absorption wavelength: 604 nm), all manufactured by Yamada Chemical Co., Ltd., but is not limited thereto.

[0060] [Embodiment 2] Next, embodiment 2 of the present disclosure will be described with reference to Figures 18 to 22. The display device 2 of this embodiment differs from embodiment 1 described above in that it includes a light diffusion layer 31. The rest is as described in embodiment 1. For convenience of explanation, members having the same functions as members shown in the drawings of embodiment 1 are given the same reference numerals, and their description will be omitted.

[0061] 18 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 2 of Embodiment 2. FIG. 19 is a diagram showing a transmission spectrum when the wavelength selective film 30a provided in the display device 2 of Embodiment 2 shown in FIG. 18 is observed from the front direction (θ=0°), and an emission spectrum of white light from the display area DA of the display device 2 of Embodiment 2 before passing through the wavelength selective film 30a (when the display area DA is observed from the front direction (θ=0°) and from an oblique direction (θ=45°)). FIG. 20 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 2a of Comparative Example 3. FIG. 21 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 2b of Comparative Example 4. FIG. 22 is a diagram showing the optical characteristics of the display device 2a of Comparative Example 3, the optical characteristics and characteristics of the wavelength selective film 30a′ of the display device 2b of Comparative Example 4, and the optical characteristics and characteristics of the wavelength selective film 30a of the display device 2 of Embodiment 2.

[0062] In the display device 2 of embodiment 2 shown in Fig. 18, a light diffusion layer 31 is provided between the red light emitting element 5R, the green light emitting element 5G, and the blue light emitting element 5B and the wavelength selective film 30a. Specifically, in the display device 2 of embodiment 2 shown in Fig. 18, a sealing layer 6 is provided between the red light emitting element 5R, the green light emitting element 5G, and the blue light emitting element 5B and the wavelength selective film 30a, and a light diffusion layer 31 is provided between the sealing layer 6 and the wavelength selective film 30a.

[0063] 19, in the emission spectrum of white light from the display area DA before passing through the wavelength selective film 30a, when the display area DA is observed from an oblique direction (θ=45°), the second emission maximum wavelength EMA2' and the third emission maximum wavelength EMA3' are each shifted relatively significantly toward lower wavelengths compared to the second emission maximum wavelength EMA2 and the third emission maximum wavelength EMA3 when the display area DA is observed from the front direction (θ=0°). Furthermore, when the display area DA is observed from an oblique direction (θ=45°), the relative radiance at the third emission maximum wavelength EMA3' is significantly lower than the relative radiance at the third emission maximum wavelength EMA3 when the display area DA is observed from the front direction (θ=0°).

[0064] As shown in Figure 19, when the display area DA of the display device 2 is displayed in white, the emission spectrum of white light from the display area DA before passing through the wavelength selection film 30a has first emission maximum wavelengths EMA1 and EMA1', second emission maximum wavelengths EMA2 and EMA2', third emission maximum wavelengths EMA3 and EMA3', first emission minimum wavelengths EMI1 and EMI1' in the wavelength region between the first emission maximum wavelengths EMA1 and EMA1' and the second emission maximum wavelengths EMA2 and EMA2', and second emission minimum wavelengths EMI2 and EMI2' in the wavelength region between the second emission maximum wavelengths EMA2 and EMA2' and the third emission maximum wavelengths EMA3 and EMA3'.

[0065] 19, the wavelength value corresponding to the first transmittance minimum value TMI1 of the wavelength selective film 30a is on the longer wavelength side than the first emission minimum wavelengths EMI1 and EMI1', and the wavelength value corresponding to the second transmittance minimum value TMI2 of the wavelength selective film 30a is on the longer wavelength side than the second emission minimum wavelengths EMI2 and EMI2'. Note that Fig. 19 only shows the transmission spectrum when the wavelength selective film 30a is observed from the front (θ = 0°) and does not show the transmission spectrum when the wavelength selective film 30a is observed from an oblique direction (θ = 45°). However, similar to the wavelength selective film 30 described above in the first embodiment, the optical characteristics of the wavelength selective film 30a do not depend greatly on the observation angle θ.

[0066] Unlike the wavelength selective film 30 provided in the display device 1 shown in Fig. 2, the wavelength selective film 30a provided in the display device 2 of this embodiment shown in Fig. 18 and Fig. 19 receives light that has passed through the light diffusion layer 31. Therefore, the transmission spectrum of the wavelength selective film 30a shown in Fig. 19, which is necessary to suppress color change when observed from an oblique direction, differs from the transmission spectrum of the wavelength selective film 30 shown in Fig. 5.

[0067] The display device 2a of Comparative Example 3 shown in Figure 20 differs from the display device 2 of Embodiment 2 shown in Figure 18 only in that it does not have a wavelength selection film 30a, and the display device 2b of Comparative Example 4 shown in Figure 21 differs from the display device 2 of Embodiment 2 shown in Figure 18 only in that it has a wavelength selection film 30a' that is different from the wavelength selection film 30a.

[0068] Although not shown, the wavelength selective film 30a' provided in the display device 2b of Comparative Example 4 differs from the wavelength selective film 30a provided in the display device 2 of Embodiment 2 in that the third transmittance maximum value is greater than the second transmittance maximum value but smaller than the first transmittance maximum value. Therefore, in the case of the display device 2b of Comparative Example 4 including the wavelength selective film 30a', it is not possible to improve the problem that the value of the radiation intensity when observed from an oblique direction is significantly lower than the radiation intensity when observed from the front direction for light on the long wavelength side, for example, red light, compared to blue light or green light.

[0069] 22, the wavelength selection film 30a′ differs from the wavelength selection film 30a provided in the display device 2 of embodiment 2 in that the wavelength value (497 nm) corresponding to the first transmittance minimum value TMI1 is on the shorter wavelength side compared to the wavelength value (506 nm) corresponding to the first transmittance minimum value TMI1 of the wavelength selection film 30a, and is the same wavelength as the first emission minimum wavelength EMI1 (497 nm) shown in FIG. 19, and the wavelength value (590 nm) corresponding to the second transmittance minimum value TMI2 is on the shorter wavelength side compared to the wavelength value (596 nm) corresponding to the second transmittance minimum value TMI2 of the wavelength selection film 30a, and is also on the shorter wavelength side compared to the second emission minimum wavelength EMI2 (593 nm) shown in FIG. Therefore, in the case of the display device 2b of Comparative Example 4, which is equipped with the wavelength selective film 30a', the optical characteristics related to oblique coloring (Δu'v' (θ = 45°)) deteriorate from 0.009 to 0.023, as shown in Figure 22, compared to the display device 2 of Embodiment 2, which is equipped with the wavelength selective film 30a.

[0070] In order to improve the optical characteristics related to oblique coloring (Δu'v' (θ=45°)), it is preferable that the wavelength selection film 30a has a wavelength value corresponding to the first transmittance minimum value TMI1 in the wavelength range of 500 nm or more and 520 nm or less, and a wavelength value corresponding to the second transmittance minimum value TMI2 in the wavelength range of 595 nm or more and 610 nm or less. As shown in Figures 19 and 22, the wavelength selection film 30a provided in the display device 2 of this embodiment has a wavelength value (506 nm) corresponding to the first transmittance minimum value TMI1 that is longer than the first emission minimum wavelength EMI1 (497 nm), and a wavelength value (596 nm) corresponding to the second transmittance minimum value TMI2 that is longer than the second emission minimum wavelength EMI2 (593 nm), so there is no deterioration in optical characteristics related to oblique coloring (Δu'v' (θ = 45°)) as with the wavelength selection film 30a' described above.

[0071] Furthermore, in terms of improving the optical characteristics related to oblique coloring (Δu'v' (θ=45°)), it is preferable that the transmission spectrum of the wavelength selection film 30a has a first full width at half maximum HW1, which is the width of the first valley having its bottom at the first transmittance minimum value (TMI1) in the transmittance calculated by ((first transmittance maximum value TMA1 + first transmittance minimum value TMI1) / 2), of 30 nm or more and 40 nm or less, and a second full width at half maximum HW2, which is the width of the second valley having its bottom at the second transmittance minimum value (TMI2) in the transmittance calculated by ((second transmittance maximum value TMA2 + second transmittance minimum value TMI2) / 2), of 30 nm or more and 40 nm or less, as shown in Figures 19 and 22. As shown in FIG. 22, the wavelength selection film 30a provided in the display device 2 of this embodiment has a first full width at half maximum HW1 of 39 nm and a second full width at half maximum HW2 of 37 nm, and therefore does not suffer from deterioration in optical characteristics related to oblique coloring (Δu'v' (θ=45°)) as seen in the above-mentioned wavelength selection film 30a' having a first full width at half maximum HW1 of 48 nm and a second full width at half maximum HW2 of 69 nm.

[0072] The wavelength selection film 30a provided in the display device 2 of this embodiment has a wavelength value corresponding to the first transmittance minimum value TMI1, a wavelength value corresponding to the second transmittance minimum value TMI2, a first full width at half maximum HW1, and a second full width at half maximum HW2, which are preferable in terms of improving the optical characteristics related to oblique coloring (Δu'v' (θ=45°)).Therefore, as shown in Figure 22, a display device 2 can be realized in which the optical characteristics related to oblique coloring (Δu'v' (θ=45°)) are significantly improved to 0.009 compared to the display device 2a of Comparative Example 3 and the display device 2b of Comparative Example 4.

[0073] Furthermore, from a comparison of the optical characteristics regarding coloring (Δu′v′ (θ=45°)) when viewed from a perspective between a display device 2 a of Comparative Example 3 shown in FIG. 20 that is provided with a light diffusion layer 31 and a display device 1 a of Comparative Example 1 shown in FIG. 10 that is not provided with a light diffusion layer 31, a comparison of the optical characteristics regarding coloring (Δu′v′ (θ=45°)) when viewed from a perspective between a display device 2 b of Comparative Example 4 shown in FIG. 21 that is provided with a light diffusion layer 31 and a display device 1 b of Comparative Example 2 shown in FIG. 13 that is not provided with a light diffusion layer 31, and a comparison of the optical characteristics regarding coloring (Δu′v′ (θ=45°)) when viewed from a perspective between a display device 2 of Embodiment 2 shown in FIG. 18 that is provided with a light diffusion layer 31 and a display device 1 of Embodiment 1 shown in FIG. 2 that is not provided with a light diffusion layer 31, it can be confirmed that in any case, when the light diffusion layer 31 is provided, the optical characteristics regarding coloring (Δu′v′ (θ=45°)) when viewed from a perspective are improved.

[0074] Furthermore, in the wavelength selection film 30a provided in the display device 2 of this embodiment, as shown in Figure 19, the third transmittance maximum value TMA3 is larger than the first transmittance maximum value TMA1 and the second transmittance maximum value TMA2, so a display device 2 can be realized with a high transmittance of 77.6%, compared to the transmittance (54.1%) of the display device 2b of Comparative Example 4.

[0075] Furthermore, by providing the wavelength selective film 30a, a display device 2 can be realized which has a reflectance of 27.7%, which is lower than the reflectance (48.2%) of the display device 2a of Comparative Example 3, and which can reduce external light reflection.

[0076] In the wavelength selective film 30a provided in the display device 2, the second transmittance maximum values ​​TMA2 and TMA2' are preferably larger than the first transmittance maximum values ​​TMA1 and TMA1'. In this embodiment, as shown in Fig. 19, a case in which the second transmittance maximum values ​​TMA2 and TMA2' are slightly larger than the first transmittance maximum values ​​TMA1 and TMA1' will be described as an example, but the present invention is not limited to this. The second transmittance maximum values ​​TMA2 and TMA2' may be significantly larger than the first transmittance maximum values ​​TMA1 and TMA1' as long as they are smaller than the third transmittance maximum values ​​TMA3 and TMA3'. In this case, a display device can be realized that reduces the possibility that the radiation intensity of light on the longer wavelength side, for example, green light, when observed from an oblique direction will be significantly lower than the radiation intensity when observed from the front direction, compared to blue light.

[0077] The wavelength selective film 30a provided in the display device 2 can be formed, for example, by dissolving a visible light absorbing material capable of selectively absorbing light in a specific wavelength range in the visible light range (400 nm to 750 nm) in a solvent to prepare a coating solution, applying the coating solution to a predetermined film, and then removing the solvent. Furthermore, if the wavelength selective film 30a contains a transparent adhesive (OCA (Optical Clear Adhesive)), for example, the transparent adhesive can be mixed into the coating solution. In this embodiment, the same material as in the first embodiment can be used as the visible light absorbing material.

[0078] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0079] The present disclosure can be used in a display device.

[0080] 1, 2 Display device 3 Barrier layer 4 Thin film transistor layer 5R Red light emitting element (light emitting element) 5G Green light emitting element (light emitting element) 5B Blue light emitting element (light emitting element) 6 Sealing layer 12 Substrate 16, 18, 20 Inorganic insulating film 21 Planarization film 22 First electrode 23 Bank 23HI Hole injection layer 23HT Hole transport layer 23EM Red light emitting layer 23ET Electron transport layer 23EI Electron injection layer 24R Functional layer including red light emitting layer 24G Functional layer including green light emitting layer 24B Functional layer including blue light emitting layer 25 Second electrode 26, 28 Inorganic sealing film 27 Organic film 30, 30a, 30OC Wavelength selection film 31 Light diffusion layer DM Display surface MC Cavity structure OCA Transparent adhesive TMA1, TMA1' First transmittance maximum value TMA2, TMA2' Second transmittance maximum value TMA3, TMA3' Third transmittance maximum value TMI1, TMI1' First transmittance minimum value TMI2, TMI2' Second transmittance minimum value HW1, HW1' First valley width HW2, HW2' Second valley width EMA1, EMA1' First emission maximum wavelength EMA2, EMA2' Second emission maximum wavelength EMA3, EMA3' Third emission maximum wavelength EMI1, EMI1' First emission minimum wavelength EMI2, EMI2' Second emission minimum wavelength R1 First wavelength region R2 Second wavelength region R3 Third wavelength region PIX Pixel RSP Red subpixel GSP Green subpixel BSP Blue subpixel TR Transistor SEM, SEM', SEM'' Semiconductor film G Gate electrode D Drain electrode S Source electrode DA Display area NDA Frame area

Claims

1. A light-emitting element including a first electrode, a second electrode, and a light-emitting layer provided between the first electrode and the second electrode, the first electrode and the second electrode forming a cavity structure; a display region in which a plurality of the light-emitting elements are provided; and a wavelength selection film provided in an upper layer than the plurality of light-emitting elements in the display region, the plurality of light-emitting elements including a first light-emitting element having a first maximum emission wavelength in a first wavelength region, a second light-emitting element having a second maximum emission wavelength in a second wavelength region that is a region longer in wavelength than the first wavelength region, and a third light-emitting element having a third maximum emission wavelength in a third wavelength region that is a region longer in wavelength than the second wavelength region, a transmission spectrum of the wavelength selective film has a first transmittance maximum value in the first wavelength region, a second transmittance maximum value in the second wavelength region, a third transmittance maximum value in the third wavelength region that is greater than the first transmittance maximum value and the second transmittance maximum value, a first transmittance minimum value in a wavelength region between a wavelength value corresponding to the first transmittance maximum value and a wavelength value corresponding to the second transmittance maximum value, and a second transmittance minimum value in a wavelength region between a wavelength value corresponding to the second transmittance maximum value and a wavelength value corresponding to the third transmittance maximum value; when the display region is displayed in white, an emission spectrum of white light from the display region before passing through the wavelength selective film has the first emission maximum wavelength, the second emission maximum wavelength, the third emission maximum wavelength, a first emission minimum wavelength in a wavelength region between the first emission maximum wavelength and the second emission maximum wavelength, and a second emission minimum wavelength in a wavelength region between the second emission maximum wavelength and the third emission maximum wavelength; a wavelength value corresponding to the first transmittance minimum value being on the longer wavelength side than the first emission minimum wavelength, and a wavelength value corresponding to the second transmittance minimum value being on the longer wavelength side than the second emission minimum wavelength.

2. The display device according to claim 1, wherein the emission spectrum is an emission spectrum when the display surface of the display area is observed from an oblique direction.

3. A display device as described in claim 1 or 2, wherein a wavelength value corresponding to the second transmittance maximum value is on the longer wavelength side than the second emission maximum wavelength, and a wavelength value corresponding to the third transmittance maximum value is on the longer wavelength side than the third emission maximum wavelength.

4. The display device according to claim 3, wherein the wavelength value corresponding to the first maximum transmittance value is on the longer wavelength side than the first maximum emission wavelength.

5. A display device described in any one of claims 1 to 4, wherein the wavelength selective film has a wavelength value corresponding to the first minimum transmittance value in a wavelength range of 500 nm or more and 520 nm or less, and has a wavelength value corresponding to the second minimum transmittance value in a wavelength range of 595 nm or more and 610 nm or less.

6. A display device as described in any one of claims 1 to 5, wherein the transmission spectrum of the wavelength selective film includes a first valley portion having the first transmittance minimum value as a valley bottom and a second valley portion having the second transmittance minimum value as a valley bottom, the width of the first valley portion in the transmittance calculated by ((the first transmittance maximum value + the first transmittance minimum value) / 2) is 30 nm or more and 40 nm or less, and the width of the second valley portion in the transmittance calculated by ((the second transmittance maximum value + the second transmittance minimum value) / 2) is 30 nm or more and 40 nm or less.

7. A display device according to claim 1, wherein the second maximum transmittance value of the wavelength selective film is greater than the first maximum transmittance value.

8. A display device described in any one of claims 1 to 7, wherein the first wavelength range is a wavelength range of 400 nm or more and less than 500 nm, the second wavelength range is a wavelength range of 500 nm or more and less than 600 nm, and the third wavelength range is a wavelength range of 600 nm or more and less than 700 nm.

9. The display device according to any one of claims 1 to 8, further comprising a light diffusing layer provided between the plurality of light emitting elements and the wavelength selection film.

10. The display device according to any one of claims 1 to 8, further comprising a sealing layer provided between the plurality of light-emitting elements and the wavelength selection film.

11. A display device described in any one of claims 1 to 8, wherein a sealing layer is provided between the plurality of light-emitting elements and the wavelength selection film, and a light diffusion layer is provided between the sealing layer and the wavelength selection film.

12. The display device according to any one of claims 1 to 11, further comprising a functional film provided directly above the wavelength selective film, the wavelength selective film including a transparent adhesive.

13. A display device as claimed in any one of claims 1 to 12, wherein the first light-emitting element has as its light-emitting layer a first light-emitting layer that emits blue light, the second light-emitting element has as its light-emitting layer a second light-emitting layer that emits green light, and the third light-emitting element has as its light-emitting layer a third light-emitting layer that emits red light.

14. The display device according to claim 13, wherein the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are organic light-emitting layers.

15. The display device according to claim 13, wherein the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer are light-emitting layers containing quantum dots.

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