JP7703467B2 - Light-emitting device, display device, imaging device, and electronic device - Google Patents

Description

The present invention relates to a light-emitting device, a display device, an imaging device, and an electronic device.

An organic light-emitting element (also called an organic EL element or OLED) is an electronic element having a pair of electrodes and an organic compound layer disposed between the electrodes. By injecting electrons and holes from the pair of electrodes into the organic compound layer, excitons of the light-emitting organic compound in the organic compound layer are generated, and when the excitons return to the ground state, the organic light-emitting element emits light. Recent progress in organic light-emitting elements has been remarkable, with advances being made in low driving voltages, diverse emission wavelengths, high-speed response, and thinner and lighter light-emitting devices. On the other hand, organic light-emitting elements have low light extraction efficiency because much of the light is trapped within the device and not extracted to the outside. In order to improve the light extraction efficiency, a light extraction structure such as a microlens may be provided in the organic light-emitting element. Patent Document 1 describes an organic light-emitting device in which a microlens is provided as an outcoupling component to increase the amount of light extracted from the OLED. In the organic light-emitting device of Patent Document 1, the diameter of the microlens and the distance between the lens and the light-emitting area are specified to address the issues of optical crosstalk and low contrast due to backscattering.

JP 2017-17013 A

However, the organic light-emitting device in Patent Document 1 does not specify interference conditions, and is not sufficiently configured to emit the desired light in the normal direction of the substrate (i.e., the front direction).

The present invention has been made in consideration of the above problems, and its purpose is to provide an organic light-emitting element that has high radiance in the front direction by providing a light extraction structure such as a microlens and using optical interference that takes the light extraction structure into consideration.

One embodiment of the present invention is a light-emitting device comprising an insulating layer, a light-emitting element including a luminescent material and having a resonator structure disposed on a principal surface of the insulating layer, and a light extraction structure provided on the light-emitting element, the light-emitting device having an electrode between the principal surface of the insulating layer and the luminescent material for supplying electric charge to the luminescent material, the PL spectrum of the luminescent material having a first peak at a wavelength λ _pl within a visible light region,
The light emitting device is characterized in that, in the resonator structure, a resonance peak wavelength λ _on of an interference spectrum that intensifies light emitted in a direction perpendicular to the main surface, a peak wavelength λ _EL of EL emission radiated via the light extraction structure, and the λ _pl satisfy the following formula (1):
|λ _EL -λ _pl | < |λ _on -λ _pl | (1)

According to the present invention, by providing a light extraction structure and using optical interference that takes the light extraction structure into consideration, it is possible to provide an organic light-emitting element that has high radiance in the front direction.

1A is a plan view of a light emitting device according to an embodiment of the present invention, and FIG. 1A is a schematic cross-sectional view of an example of a light-emitting device in which a light-extraction structure has a convex microlens on the side opposite to a substrate, and FIG. 1B is a schematic cross-sectional view of an example of a light-emitting device in which a light-extraction structure has a convex microlens on the substrate side. 1A is a schematic diagram showing light emitted from a light emitting point toward the front of the light emitting device, and FIG. 1B is a schematic diagram showing light emitted from the light emitting point in a direction inclined with respect to the main surface of the substrate. 11A to 11D are schematic diagrams showing a method for estimating Θ _eml , taking a spherical microlens as an example of a light extraction structure. (a) is a graph showing the PL spectrum and the interference spectrum λ _off and λ _on of a luminescent material according to a comparative embodiment; (b) is a graph showing the PL spectrum and the interference spectrum λ _off and λ _on of a luminescent material in a light-emitting element that reinforces light emitted in a direction inclined to the main surface of the substrate; (c) and (d) are EL spectra of (a) and (b). 1A is a schematic diagram showing light refracted by a microlens in a conventional configuration in which the microlens is shifted to match the interference peak resonance wavelength λ _on in the front direction of the substrate main surface with λ _PL , and FIG. 1B is a schematic diagram showing light refracted by a microlens in a configuration in which the interference peak resonance wavelength λ _off in a direction inclined to the substrate main surface with λ _PL is matched. 7A is a plan view of a display area showing that the relative positions of the microlenses and the pixels vary depending on the position in the display area, and FIG. 7B is a schematic cross-sectional view taken along line E-E' in FIG. 5A to 5D are diagrams illustrating other configuration examples of the light emitting device according to one embodiment of the present invention. 1 is a diagram showing the relationship between the radiation angle and the relative light amount in a light-emitting layer obtained by ray tracing. 1 shows the PL spectrum PL1 of the luminescent material used in Example 1. FIG. 1 is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention. 1A is a schematic diagram illustrating an example of an imaging device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of an electronic device according to an embodiment of the present invention. 1A is a schematic diagram illustrating an example of a display device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram illustrating an example of a foldable display device. 1A is a schematic diagram showing an example of a wearable device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram showing an example of a wearable device according to an embodiment of the present invention, the wearable device having an imaging device.

The light-emitting device according to one embodiment of the present invention has an organic film interference structure that is aligned with the inclined portion of the light-extraction structure, thereby increasing the radiation intensity in the front direction of the organic EL element having the light-extraction structure. This is because the light of the PL peak wavelength of the light-emitting material is effectively intensified and refracted in the front direction at the inclined portion of the light-extraction structure. The light-emitting device has an electrode between the main surface of the insulating layer and the light-emitting material that supplies electric charge to the light-emitting material, and the end and other end of the electrode are covered with a pixel separation layer.

That is, a light emitting device according to one embodiment of the present invention includes an insulating layer, a light emitting element including a light emitting substance and having a resonator structure, the light emitting element being disposed on a main surface of the insulating layer, and a light extraction structure being provided on the light emitting element,
The PL spectrum of the luminescent material has a first peak having a wavelength λ _PL within the visible light region, and the resonator structure has a resonant peak wavelength λ _on of an interference spectrum that intensifies light emitted in a direction perpendicular to the main surface, a peak wavelength λ _EL of EL emission radiated via the light extraction structure, and the λ _PL satisfy the following formula (1):
|λ _EL -λ _PL | < |λ _on -λ _PL | (1)

Furthermore, a light emitting device according to one embodiment of the present invention may be a light emitting device comprising an insulating layer, a light emitting element containing a luminescent material and having a resonator structure disposed on a principal surface of the insulating layer, and a light extraction structure provided on the light emitting element, wherein the PL spectrum of the luminescent material has a first peak having a wavelength λ _PL within a visible light region, and wherein in the resonator structure, a resonant peak wavelength λ _on of an interference spectrum that enhances light emitted in a direction perpendicular to the principal surface, a resonant peak wavelength λ _off of an interference spectrum that enhances light emitted in a direction perpendicular to the principal surface due to refraction in the light extraction structure, and the λ _PL satisfy the following formula (2):
|λ _off -λ _PL | < |λ _on -λ _PL | (2)

In another embodiment, λ _off can be the distance from the light emitting region to the bottom end of the upper electrode of the light emitting element in the direction of the curved surface of the light extraction structure, and λ _on can be the distance from the light emitting region to the bottom end of the upper electrode of the light emitting element in the direction perpendicular to the insulating layer. Since the actual distance is used, the design is easy.

The following describes a light-emitting device according to one embodiment of the present invention with reference to the drawings. Note that publicly known techniques in the relevant technical field can be applied to parts not specifically illustrated or described in this specification. Furthermore, the present invention is not limited to the embodiment described below.

Figure 1(a) is a plan view of a light-emitting device according to one embodiment of the present invention. In this embodiment, the light-emitting device is a display device in which a plurality of light-emitting elements, including a first light-emitting element and a second light-emitting element, are arranged, each emitting a different color to display an image or the like. The display device has a display area 1 in which light-emitting elements 3 are arranged two-dimensionally on the main surface of an insulating layer such as a substrate, and in which images or the like are displayed. The arrangement of the light-emitting elements in Figure 1 is a delta arrangement, but may also be a stripe arrangement, a square arrangement, a pentile arrangement, or a Bayer arrangement. The ends of the display area are indicated by dashed lines and are referred to as ends 2.

Figure 1(b) is an enlarged view of the dashed line portion shown at end 2 in Figure 1(a). It has a light-emitting element 3 arranged on the main surface of the insulating layer, and a light extraction structure 4 into which light from the light-emitting region of the light-emitting element 3 is incident. In Figure 1(b), the center of the light-emitting region and the center of the light extraction structure coincide in a plan view from a direction perpendicular to the main surface of the substrate. In this embodiment, the light-emitting region is hexagonal in shape, but the shape is not limited. If the light-emitting region is polygonal, the center can be estimated as the center of the inscribed circle of the polygon. If the light-emitting region is circular, the center of the circle can be estimated as the center of the light-emitting region.

FIG. 2 is a schematic cross-sectional view of a light-emitting device according to one embodiment of the present invention. Here, the schematic cross-sectional view is the arrangement when the light-emitting device is viewed from a direction perpendicular to the main surface of the insulating layer (the normal direction of the main surface). FIG. 2(a) is an example in which the light-extraction structure of the light-emitting device is a microlens that is convex on the opposite side to the substrate. The light-emitting device according to this embodiment has a reflective layer 6, an organic layer 7 having a light-emitting substance, a semi-transparent electrode 8, a protective layer 9, and a microlens 10 on a substrate 5. The reflective layer 6 and the semi-transparent electrode 8 are also called the lower electrode and the upper electrode, respectively, based on their positions. The PL spectrum of the light-emitting substance has a first peak with a wavelength of λ _PL in the visible light region. The light-emitting device may have a resonator structure that intensifies the light emission due to the optical distance between the reflective layer 6 and the semi-transparent electrode 8. Here, the organic layer 7 is used for the description, but as long as the light-emitting device is an organic or inorganic light-emitting device, it does not matter. In particular, when the light-emitting substance is organic, the light-emitting device of this embodiment can be called an organic light-emitting device, and the light-emitting device can be called an organic light-emitting device. In this embodiment, the reflective layer also functions as an electrode, and therefore can also be called a reflective electrode.

In the resonator structure, the resonant peak wavelength λ _on of the interference spectrum that intensifies the light emitted in a direction perpendicular to the main surface of the substrate is present. Emitting light in a direction perpendicular to the main surface of the substrate can also be referred to as light that is extracted in a direction perpendicular to the main surface of the substrate without a light extraction structure. In other words, the light is emitted in the front direction of the substrate, regardless of refraction due to the light extraction structure. The resonator structure also has a peak wavelength λ _EL of the EL emission emitted through the light extraction structure. λ _EL is the wavelength of the light emitted in front of the substrate, taking into account the optical interference due to the resonator structure and the refraction due to the light extraction structure. Here, the PL emission and the PL spectrum are properties of the light-emitting material, regardless of the structure of the light-emitting element. The PL spectrum can be obtained, for example, by forming a light-emitting layer containing a light-emitting material of an organic light-emitting element on a substrate and causing it to emit light by photoexcitation. It is preferable to reproduce the light-emitting layer, but the PL emission can be measured if it is a solid film of the light-emitting material. In contrast, the EL emission and the EL spectrum are light-emitting characteristics that take into account the optical distance between the electrodes and the influence of the light extraction structure.

The light emitting device according to this embodiment is a light emitting device in which λ _PL , which is the first peak of the light emitting substance, λ _EL , and λ _on satisfy the following formula (1). By satisfying this formula, a light emitting device with good luminance emitted from the front of the substrate can be obtained.
|λ _EL -λ _PL | < |λ _on -λ _PL | (1)

Satisfying formula (1) indicates that the difference between the wavelength of the EL emission and the first peak wavelength of the luminescent material is smaller than the difference between the interference peak λ _on and the first peak wavelength of the luminescent material.

|λ _on −λ _PL | may be less than the full width at half maximum of λ _PL .

The light emitting device according to this embodiment has a resonant peak wavelength λ _off of an interference spectrum that intensifies light emitted in a direction perpendicular to the main surface of the substrate due to refraction in the light extraction structure in a resonator structure. The light emitted in the front direction of the substrate due to refraction in the light extraction structure is light that is inclined with respect to the main surface of the substrate in the light emission direction from the light emitting material and the reflection direction in the reflective layer. In Fig. 2(a), radiated light 12 is emitted from a point 11 where the light emitting material is emitting light. The radiated light is refracted at the inclined portion 13 of the microlens 10 and is emitted in the front direction of the substrate.

The light emitting device according to this embodiment is a light emitting device in which λ _PL , λ _off , and λ _on satisfy the following formula (2), and by satisfying this formula, a light emitting device with good luminance emitted from the front surface of the substrate can be obtained.
|λ _off -λ _PL | < |λ _on -λ _PL | (2)

Formula (2) indicates that the difference between the interference peak λoff and the first peak wavelength of the luminescent material is smaller than the difference between the interference peak λon and the first peak wavelength of the luminescent material. In other words, it indicates that the first peak wavelength of the luminescent material is closer to the interference peak that strengthens the light emitted in the front direction of the substrate through the light extraction structure than the interference peak that strengthens the light emitted in the front direction of the substrate. In other words, the interference peak that strengthens the light emitted at an angle inclined to the substrate is closer to the first peak of the luminescent material. Here, the first peak may be the maximum intensity peak in the PL spectrum of the luminescent material in the visible range. If the PL spectrum has a second peak, the second peak may be the peak with the second highest intensity after the first peak. The luminescent material is also called a luminescent dopant. | _λon - _λPL | may be equal to or less than the full width at half maximum of λPL.

Furthermore, in the case where there is a second peak, it is preferable that the wavelength of the second peak is designated as λ _PL2 and that the following formula (3) is satisfied.
|λ _off −λ _PL | ≦ |λ _on −λ _PL2 | (3)

Formula (3) indicates that the difference between the interference peak λ _off and the first peak λ _PL is smaller than the difference between the interference peak λ _on and the second peak λ _PL2 . In other words, the first peak may be given priority over the second peak and designed to match the interference peak. Note that the first peak may coincide with λ _off , and the second peak may coincide with λ _on . When formula (3) is satisfied, it is preferable because the luminance on the front side of the substrate can be further improved. |λ _on - _{λ PL2} | may be equal to or less than the full width at half maximum of the second peak.

In contrast, the light emitting device has a second light emitting element different from the light emitting element, and the second light emitting element may be an element that does not satisfy formula (1). The second light emitting element may be an element that emits light of a different color than the light emitting element. Since the light emitting element has a different light emitting color, the light emitting element may have a light emitting element that does not satisfy either formula (1) or formula (2), taking into consideration the balance of front luminance. The light emitting color of the second light emitting element that does not satisfy formula (1) or formula (2) may be determined by the balance of RGB of the light emitting device, and may be blue, green, red, or a combination thereof.

In a light-emitting device according to one embodiment of the present invention, an element that prioritizes front luminance may be an element that satisfies (1) or (2) and (3), and an element that prioritizes color purity may be an element that does not satisfy (3). Also, an element that prioritizes color purity may not need to satisfy (1) and (2).

The element that prioritizes front luminance may be an element that emits green, and the element that prioritizes color purity may be an element that emits blue. In another embodiment, the element that prioritizes front luminance may be an element that emits blue, and the element that prioritizes color purity may be an element that emits green. In yet another embodiment, the element that prioritizes front luminance may be an element that emits red, and the element that prioritizes color purity may be a green element or an element that emits blue.

The second light-emitting element may have a second light-emitting material that is different from the light-emitting material of the first light-emitting element.

The full width at half maximum of the PL spectrum of the second luminescent material may be equal to or greater than the full width at half maximum of the PL spectrum of the luminescent material possessed by the first light-emitting element.

The full width at half maximum of the PL spectrum here refers to the width of the first peak at an intensity of 0.5 when the PL intensity of the first peak is taken as 1. In a light-emitting substance with large first and second spectral widths, the minimum value of the PL intensity in the boundary region between the first and second peaks may be 0.5 or more. In such cases, the spectral width at an intensity of 0.5 for the spectrum obtained by adding together the spectral components of the first and second peaks becomes the full width at half maximum. Also, if the spectral width of the first peak is very large, it may appear as if the second peak does not exist. In this case, the full width at half maximum refers to the width of the entire PL spectrum at an intensity of 0.5.

The luminescent material having an emission spectrum with a first peak and a second peak may be a fluorescent material or a delayed fluorescent material. The delayed fluorescent material may be of the thermally activated type. In contrast, the second luminescent material having a small second peak or no second peak may be a phosphorescent material.

In other words, the light-emitting element having a fluorescent material may satisfy formula (1) or (2) in the present specification, and the second light-emitting element having a phosphorescent material may be in a form that does not satisfy either formula (1) or (2) in the present specification.

The emission color of the second light-emitting element may be green. The width of the PL spectrum of the second light-emitting material may be narrower than that of the other light-emitting elements. The green wavelength is in the region between blue and red, and is not to overlap with other colors.

Since the λ _off of the light emitting device according to this embodiment tends to intensify light having a radiation angle of 15° with respect to the main surface of the substrate, the λ _off may be set to an interference peak resonance wavelength that intensifies light having a radiation angle of 15°.

To configure the light-emitting device according to this embodiment, specifically, the interference peak resonance wavelength in the front direction, which is determined by the material and film thickness of the organic layer of the light-emitting element, is set to the longer wavelength side than the PL peak wavelength of the light-emitting substance. By setting it to the longer wavelength side, light near the PL peak wavelength with the highest intensity in the PL spectrum of the light-emitting substance can be emitted toward the inclined portion of the light extraction structure. This inclined portion refracts light toward the front direction of the substrate, improving the brightness in the front direction. The configuration of the light-emitting device according to the present invention can be said to be a unique optical interference condition in a light-emitting element having a light extraction structure. The inclined portion of the light extraction structure is preferably at least 0° and less than 90° with respect to the main surface of the substrate, and more preferably at least 9° and less than 60°. By setting it in this range, the brightness in the front direction of the substrate can be improved.

Strengthening the optical interference condition means adjusting the distance _d0 from the light-emitting position of the light-emitting layer to the reflecting surface of the light-reflecting material to _d0 = mλ/ _4n0 (i = 1, 3, 5, ...) to achieve constructive interference. As a result, the radiation distribution of light with wavelength λ contains more components in a specific direction, improving the radiance at a specific angle.

When the optical distance Lr from the light emitting position to the reflecting surface of the light reflecting layer reinforces the wavelength λ, Lr is expressed by the following formula (4).
Lr=(2m-(φr/π))×(λ/4)×1/cos(θ _eml ) (4)

In the above formula (4), m is the order of interference between the light emitting point and the reflecting layer, and is an integer equal to or greater than 0, and n ₀ is the effective refractive index at wavelength λ of the layer from the light emitting position to the reflecting surface. In the ideal case where Φr=π, the cases of m=0 and m=1 are called the λ/4 interference condition and the 3λ/4 interference condition, respectively. φr[rad] is the sum of the phase shift amounts when light of wavelength λ is reflected on the reflecting surface, and θ _eml is the radiation angle with respect to the substrate normal direction in the light emitting layer. The optical distance Lr is the sum of the products of the refractive index nj of each layer of the organic compound layer and the thickness dj of each layer. That is, Lr can be expressed as Σn _j ×d _j , and can also be expressed as n ₀ ×d _0. φ is a negative value.

Furthermore, assuming that the optical distance Ls from the light emission position to the reflective surface of the light extraction electrode is the sum of the phase shifts when light of wavelength λ is reflected by the reflective surface of the light extraction electrode is φs [rad], when the total layer interference L intensifies the wavelength λ, L is expressed by the following formula (5): M in the following formula (5) is m+m', where m' is the order of interference between the light emission point and the light extraction electrode, and is an integer of 0 or more.
L=(Lr+Ls)=(2M−Φ/π)×(λ/4)×1/cos(θ _eml ) (5)

Here, M is the sum of the interference order m between the light emitting point and the reflective layer and the interference order m' between the light emitting point and the light extraction electrode (M = m + m'), and is an integer equal to or greater than 0. In addition, Φ is the sum of the phase shifts when light of wavelength λ is reflected by the light reflective layer and the light extraction electrode (Φ = φr + φs). Equation (5) is the interference called full-layer interference of the organic compound layer.

In the case of an organic light-emitting element that does not have an inclined surface of the light extraction structure, the thickness of the organic layer and the like are designed so as to satisfy formulas (4) and (5) in the front direction, that is, the condition that _{θ eml} =0° direction.

If the interference peak resonance wavelength in the front direction at this time is λ _on (on-axis), then equation (6) is obtained.
λ _on =4πL/(2πM−Φ) (6)

In an organic light-emitting element that does not have an inclined surface of a light extraction structure, the film thickness and material are designed so that the peak resonance wavelength λ _on in the front direction expressed by the above formula (6) approximately coincides with the peak wavelength λ _PL of the PL spectrum of the light-emitting dopant.

On the other hand, when a light extraction structure is provided, i.e., in one embodiment of the present invention, the radiation angle within the organic light-emitting element that emits light in the front direction within the pixel emission region varies depending on the pixel emission position.

2(a) and (b) are diagrams showing how the emitted light 12 emitted from a light emitting point 11 on the reflective layer 6 is refracted at an inclined portion 13 of a microlens 10 and emitted in the direction normal to the substrate. Here, the microlens 10 is illustrated as an example of the light extraction structure 4, but it is determined by the relationship between the inclination angle and the light emission position regardless of the shape of the light extraction structure. n ₀ , n ₁ , n ₂ , and n _eml in FIG. 2(a) are the refractive index outside the element, the refractive index of the microlens, the refractive index of the protective layer, and the refractive index of the organic film light emitting layer, respectively, and have a relationship of n ₀ <n _1. Here, for simplicity, n ₂ =n _eml . Also, n ₃ in FIG. 2(b) is the refractive index of the filling layer filling the space between the microlens 10 and the protective layer 9, and has a relationship of n ₃ <n ₁ . Although not shown in detail in FIGS. 2(a) and 2(b), the organic layer 7 and the protective layer 9 may each have a laminated structure, in which case the refractive index may be expressed as a weighted average value of the film thicknesses Σn _j ×d _j /Σd _j .

The distance between the inclined portion 13 of the microlens 10 having an inclination angle of ψ with respect to the principal surface of the substrate and the center of the pixel in a direction parallel to the principal surface of the substrate is R, and the distance between the inclined portion 13 and the light-emitting point 11 in a direction parallel to the principal surface of the substrate is r. In this case, the distance X between the light-emitting point 11 from which the radiated light 12 refracted in the front direction at the inclined portion 13 is emitted and the center of the pixel is given by the following formula (7). The radiation angle θ _eml of the radiated light 41 in the light-emitting layer is given by the following formula (8). The pixel center may be the midpoint of the lower electrode in a cross section perpendicular to the principal surface of the substrate. Alternatively, in the case where an insulating layer is provided at the end of the lower electrode, the pixel center may be the midpoint of an opening in the insulating layer on the lower electrode in a cross section perpendicular to the principal surface of the substrate.

d _i and n _i are the film thickness and refractive index of the i-th layer. Here, R(ψ) is a structural parameter indicating the relationship between the position of the light extraction structure and the inclination angle, and in the case of the spherical microlens exemplified in FIG. 2(a), R=A*sinψ. A is the radius of curvature of the microlens. Both X and θ _eml are functions of the inclination angle ψ of the inclined portion of the light extraction structure. That is, the pixel light-emitting area that contributes to the radiance in the front direction is determined for each inclination angle of the inclined portion of the light extraction structure, and the radiation angle in the light-emitting layer of the light emitted from the light-emitting area and refracted to the front at the inclined surface is determined. In other words, in an organic light-emitting element having a light extraction structure, it is sufficient to optimize the interference conditions according to the inclination angle at which the contribution rate is the highest among the inclined portions constituting the light extraction structure. Specifically, it is to reduce the difference between the interference peak resonance wavelength and the PL peak wavelength in the radiation angle θ _eml direction corresponding to the inclination angle at which the contribution rate is the highest.

Next, the inclined portion having the highest contribution rate will be defined, and the interference peak resonance wavelength in the radiation angle θ _eml direction corresponding to the inclination angle having the highest contribution rate will be described. The inclined portion having the highest contribution rate refers to the inclined portion having the largest light-emitting area among the pixel light-emitting ranges that can emit light refracted in the front direction at the inclined portion of the light extraction structure.

Figure 3 is a diagram showing the light extraction structure according to this embodiment extracting light in the front direction of the light emitting device. Figure 3(a) is a schematic diagram showing light emitted from a light emitting point in the front direction of the light emitting device. Figure 3(b) is a schematic diagram showing light emitted from a light emitting point in a direction inclined with respect to the main surface of the substrate. Figure 3(a) is a three-dimensional diagram showing the relationship between the light emitting area 15a and the light extraction surface 16a, and the lower part is a cross-sectional view perpendicular to the main surface of the substrate including the center of the pixel. Figure 3(a) shows the light extraction surface 16a (tilt angle 0°) that is radiated in front of the main surface of the substrate by optical interference in the front direction of the organic light emitting element, the corresponding light emitting area 15a, and the light emitting region 20a in the cross section that emits light that is emitted in the front direction. Figure 3(b) shows the light emitting area 15b that can emit light refracted in the front direction at the trapezoidal inclined part 16b (tilt angle 17b), and the light emitting region 20b in the cross section that can emit light refracted in the front direction. In the case of the trapezoidal light extraction structure shown in Figure 3, the pixel area 15b is the maximum area. In this embodiment, the light extraction structure is shown to have an inclined portion, but the shape is not important as long as the light emitted in a direction inclined relative to the main surface of the substrate can be refracted toward the front surface of the substrate.

Here, the direction of the radiation angle θ _eml corresponding to the inclined portion with the highest contribution rate is the radiation angle at the light emission point of light that is emitted from the maximum light-emitting area described above and refracted in the front direction at the inclined portion with the highest contribution rate.

3B, Θ _eml is the radiation angle of light emitted from the maximum pixel area 16a and refracted in the front direction through the inclined portion 16b. With respect to the main surface of the substrate, the interference peak resonance wavelength λ _off (off-axis) in the Θ _eml direction is expressed by the following formula (9). λ _off is also referred to as the interference peak resonance wavelength in the oblique direction below.
λ _off =4πL/(2πM-Φ)×1/cos(Θ _eml ) (9)

It is desirable to determine the optical interference conditions of the organic light-emitting element so that the difference between the interference peak resonance wavelength λ _off of the formula (9) and the _PL peak wavelength λ _PL of the light-emitting material is smaller than the difference between the interference peak wavelengths λ _on and λ PL in the front direction defined by the formula (9). Also, as illustrated in the examples, λ _off may be approximately equal to the peak wavelength λ _EL of the EL spectrum of the light-emitting device of this embodiment. In other words, the optical interference conditions of the organic light-emitting element may be determined so that the difference between λ _EL and λ _PL is smaller than the difference between the interference peak wavelengths λ _on and λ _PL in the front direction.

FIG. 4 is a schematic diagram showing a method for estimating a preferred radiation angle Θ _eml using a spherical microlens as an example of a light extraction structure. In FIG. 4(a) to (d), the angle of light emission with respect to the main surface of the substrate is different. The upper part is a three-dimensional diagram showing the relationship between the light-emitting areas 18a to 18d, the light extraction surface 19a, and the inclined parts 19b to 19d, and the lower part is a cross-sectional view perpendicular to the main surface of the substrate including the pixel center. 19a is not inclined, so it is called a light extraction surface. 19b to 19d are inclined, so they are called inclined parts, but they can also be called light extraction surfaces. Even in the microlens shown in FIG. 4, the inclined part with the highest contribution rate is the inclined part with the largest light-emitting area among the pixel light-emitting ranges that can emit light refracted in the front direction at the inclined part of the light extraction structure. In other words, in the case of a spherical microlens, the position where the light-emitting area is largest corresponds to the outermost peripheral region. Fig. 4C shows how light emitted from the maximum light-emitting area 18c among the light-emitting areas that can be refracted to the front by the inclined surface of the spherical microlens is refracted to the front by the inclined portion 19c. In the case of a microlens, the Θ _eml direction may be the radiation angle in the light-emitting layer from the outermost peripheral area 18c to the inclined portion 19c as shown in Fig. 4C. According to a ray tracing simulation, the radiation angle Θ _eml is preferably greater than 0° and less than 30°. It is more preferably greater than 5° and less than 20°.

Next, the effect of making the difference between the interference peak resonance wavelength λ _off in the oblique direction and the PL peak wavelength λ _PL of the luminescent material in formula (9) smaller than the difference between the interference peak wavelength λ _on in the front direction defined by formula (6) and λ _PL will be described.

5 is a graph showing the PL spectrum of the light-emitting substance, the interference spectrum strengthening the front direction, and the interference spectrum strengthening the tilt direction. FIG. 5(a) is a conventional example, showing the relationship between λ _off , λ _on , and λ _PL in a light-emitting device having a configuration in which light emitted in a front direction of the main surface of the substrate is strengthened. FIG. 5(b) is a configuration according to the present invention, showing a light-emitting device in which light emitted in a direction tilted with respect to the main surface of the substrate is strengthened. The configuration of FIG. 5(b) is a case in which the difference between the interference peak resonance wavelength λ _off in a direction tilted with respect to the main surface of the substrate and the PL peak wavelength λ _PL of the light-emitting substance is smaller than the difference between the interference peak λ _on and λ _PL in the front direction of the main surface of the substrate. FIG. 5(c) is a spectrum in the front direction through a microlens of the light-emitting device having the configuration of (a). FIG. 5(d) is a spectrum in the front direction through a microlens of the light-emitting device having the configuration of (b). 5A and 5B are diagrams in which the spectra of (c) and (d) are resolved into components of radiation angles within the light-emitting layer.

5 assumes a microlens as shown in FIG 4, and it is assumed that Θ _eml is approximately 15°, however, this effect does not depend on the value of Θ _eml .

θ _eml =0° in Figures 5(a) and (b) corresponds to the emission intensity of the light-emitting element when there is no light extraction structure in each light-emitting element configuration. As mentioned above, in the case of an organic light-emitting element without a light extraction structure, the interference peak wavelength λ _on in the front direction is made to match λ _PL . This is also shown by the fact that the radiance at θ _eml =0° in Figure 5(a) is greater than the radiance at θ _eml =0° in Figure 5(b). On the other hand, when a microlens is included, the contribution rate of θ _eml to the radiance in the front direction changes. In other words, the light refracted in the front direction differs depending on the angle.

In the conventional configuration shown in FIG. 5(a), the interference peak resonance wavelength λ _off at which the efficiency of light extraction to the front by the light extraction structure (hereinafter referred to as the front extraction efficiency) is the highest is located on the shorter wavelength side than the PL spectrum λ _PL . The PL spectrum has a steep spectrum drop on the short wavelength side of the PL peak. In other words, the intensity is greatly reduced. As a result, the spectrum area (radiance) on the short wavelength side of the PL peak wavelength is small. Therefore, in the wavelength region of λ _off in FIG. 5(a), although the effect of strengthening λ _off is large, the amount of light emitted from the light-emitting material is small, so the increase in the front light extraction efficiency by the light extraction structure is small. This is also shown by the small emission intensity at θ _eml =15° and 25° in FIG. 5(a).

On the other hand, when the difference between the interference peak resonance wavelength λ _off and the PL peak wavelength λ _PL in the direction inclined to the substrate main surface is smaller than the difference between the interference peak wavelength λ _on and λ _PL in the front direction of the substrate main surface, the front light extraction efficiency of the light extraction structure and the region with high emission intensity of the PL spectrum overlap. That is, the radiance at θ _eml = 15 ° and 25 ° shown in FIG. 5 (b) can be increased. Since the spectrum area of FIG. 5 (d) is larger than the spectrum area of FIG. 5 (c), the radiance of the organic light emitting element having the light extraction structure is higher in the light emitting element of FIG. 5 (d). In other words, the radiance in the front direction is higher when the difference between the interference peak resonance wavelength λ _off and the PL peak wavelength λ _PL in the direction inclined to the substrate main surface is smaller than the difference between the interference peak wavelength λ _on and λ _PL in the front direction of the substrate main surface.

In the present invention, the interference peak wavelength λ _on in the front of the substrate main surface of the organic light-emitting element having a light extraction structure is configured to be on the long wavelength side relative to the PL peak wavelength λ _PL of the light-emitting substance, so that the radiance in the front direction is large. In other words, the radiance in the front direction is dramatically increased by making the difference between the interference peak resonance wavelength λ _off in the direction tilted relative to the substrate main surface and the PL peak wavelength λ _PL smaller than the difference between the interference peak wavelengths λ _on and λ _PL in the front direction. Note that, as shown in Figures 5(b) and (d), the interference peak resonance wavelength λ _off in the direction tilted relative to the substrate main surface and the peak wavelength λ _EL of the EL spectrum are roughly the same.

In order to increase the radiance in the front direction of the main surface of the substrate, λ _off and λ _PL may be the same. In addition, when the spectrum of the luminescent material has a second peak λ _PL2 whose intensity is smaller than λ _PL , λ _PL2 may be made to match λ _on . In other words, the interference spectrum in the direction inclined to the main surface of the substrate is close to λ _PL , and the interference spectrum in the front direction of the main surface of the substrate is close to λ _PL2 . When comparing the two, λ _PL and λ _off may be closer than λ _PL2 and λ _on .

FIG. 6 is a schematic diagram showing light refracted by a microlens when the microlens is shifted. Since the interference peak resonance wavelength λ _off in the direction inclined to the main surface of the substrate is made closer to the PL peak wavelength λ _PL , the light of the PL peak wavelength can be refracted to the wider angle side by the microlens shift. The microlens shift (hereinafter, ΔML) refers to providing a distance between the center position of the microlens and the center position of the pixel opening in a direction parallel to the main surface of the substrate. The center of the microlens can be estimated at the midpoint of the microlens in a cross section perpendicular to the main surface of the substrate. The center of the pixel opening can be estimated at the midpoint of the lower electrode in a cross section perpendicular to the main surface of the substrate. In addition, when the end of the lower electrode is covered with a pixel separation layer, the center of the pixel opening can be estimated at the midpoint of the line segment from the pixel separation layer to the pixel separation layer in the cross section. These cross sections may be selected so as to pass through the apex of the microlens.

In this embodiment, the optical path length may be roughly calculated by considering the refractive index of the organic layer to be 1.9. In this case, the constant A satisfies the following formula (A) using the emission wavelength λ _PL of the luminescent material, the distance D between the electrodes, and the angle θ at which the emission is tilted.
1.9D < Aλ _PL /4 < 1.9D/cosθ (A)

In addition, Aλ _PL /4 may be closer to the value of 1.9D/cos θ than 1.9 D. In other words, this indicates that an interference spectrum tilted by an angle θ contributes more to interference of the emission wavelength λ _PL of the light-emitting substance than an interference spectrum in the front direction with respect to the substrate.

The light emitting device according to this embodiment has a second light emitting element different from the light emitting element, and a second light extraction structure different from the light extraction structure and into which light from the second light emitting element is incident, and the distance between the midpoint of the light emitting region of the light emitting element and the midpoint of the light extraction structure in a cross section perpendicular to the main surface of the substrate in a direction parallel to the main surface of the substrate may be smaller than the distance between the midpoint of the light emitting region of the second light emitting element and the midpoint of the second light extraction structure in a cross section perpendicular to the main surface of the substrate in a direction parallel to the main surface of the substrate.

The device may further include a third light-emitting element different from the second light-emitting element, and a third light extraction structure different from the second light extraction structure and into which light from the third light-emitting element is incident, and the distance in a direction parallel to the main surface of the substrate between the midpoint of the light-emitting region of the second light-emitting element in a cross section perpendicular to the main surface of the substrate and the midpoint of the second light extraction structure may be smaller than the distance in a direction parallel to the main surface of the substrate between the midpoint of the light-emitting region of the third light-emitting element in a cross section perpendicular to the main surface of the substrate and the midpoint of the third light extraction structure.

FIG. 6(a) shows a conventional configuration in which the interference peak resonance wavelength λ _on in the front direction of the substrate main surface is matched with λ _PL . FIG. 6(b) shows a configuration in which the interference peak resonance wavelength λ _off in the direction inclined to the substrate main surface is matched with λ _PL . The configuration of FIG. 6(b) shows how the light of the PL peak wavelength λ _PL is emitted to the wide-angle side by the microlens shift, compared to the configuration of FIG. 6(a). This is because FIG. 6(b) shows interference that strengthens the light in the direction inclined to the substrate main surface. Here, for simplicity, n ₁ =n ₂ =n _eml , and n ₀ <n ₁ are illustrated. Even if refraction occurs at each interface, the result is the same, that the light of λ _PL is emitted to a wider angle in FIG. 6(b) than in FIG. 6(a).

6(a) and (b), light is emitted from the light-emitting region and is bent at an angle of θ ₀ (θ' ₀ in FIG. 6(b)) by the inclined portion of the microlens. If the inclination angle of the microlens at this time is ψ (ψ' in FIG. 6(b)), the condition in FIG. 6(a) satisfies the following formula (10).
n ₀ × sin (θ ₀ + ψ) = n _eml × sin (θ _eml + ψ) (10)

Here, θ _eml is the radiation angle at the light emitting point. In FIG. 6(a) where λ _on =λ _PL , θ _eml =0°, and in FIG. 6(b) where λ _off =λ _PL , θ _eml =Θ _eml . As can be seen from FIG. 6 and formula (10), in the light emitting device according to the present invention, the light of λ _PL is incident on the inclined portion in an oblique direction as shown in FIG. 6(b), so that the light of λ _PL can be refracted to the wider angle side. The maximum value of the refraction angle derived from the total reflection condition of formula (10) is expressed by formula (11) and formula (12) when λ _on =λ _PL and when λ _off =λ _PL , respectively.
θ ₀ = π/2-sin ⁻¹ (n ₀ /n _eml ) (11)
θ ₀ '=π/2+Θ _eml -sin ^-1 (n ₀ /n _eml )=θ ₀ +Θ _eml (12)

In other words, by setting the optical interference condition of the organic light-emitting element such that the interference peak resonance wavelength λ _off in the direction inclined to the substrate main surface is close to the PL peak wavelength λ _PL , it is possible to shift the refraction direction to the wide-angle side by Θ _eml compared to the conventional configuration. In the embodiment configuration, it can be said that the angle adjustment range by microlens shift can be made wider compared to the conventional configuration. If it becomes possible to radiate to the wider angle side, a small display device can be applied to a shorter focal optical system while increasing the FOV. In other words, it is possible to miniaturize head-mounted displays, etc.

In at least a portion of the light-emitting device, the distance between the center position of the light extraction structure and the center position of the pixel opening in the in-plane direction of the substrate may be adjusted as appropriate.

Figure 7 is a plan view showing that the relative positions of the microlens and the pixel differ depending on the position of the display area. Figure 7(a) is a plan view of the display area. Figure 7(b) is a schematic cross-sectional view of E-E' in Figure 7(a). Figure 7(b) shows the relationship between the relative positions of the center of the microlens 10 and the center of the light-emitting area 22, and the position of the light-emitting element in the display area. At the center position of the display area 1, the center of the microlens and the center of the light-emitting area coincide. That is, ΔML23 is 0. The distance between the center of the microlens and the center of the light-emitting area increases as it is written further to the left in the figure. That is, ΔML24 is larger than delta ML23, and ΔML25 is larger than ΔML24. And in Figure 7(b), ΔML26 is the largest distance between the center of the microlens and the center of the light-emitting area. The distance between the center of the microlens and the center of the light-emitting region in the figure is an example, and ΔML may be increased from the center of the display region toward the edge as shown in the figure, or may be decreased from the center of the display region toward the edge. ΔML may be formed so as to change continuously from a macroscopic perspective with respect to the position of the display region. As long as it is continuous from a macroscopic perspective, ΔML may be changed for each light-emitting element, or ΔML may be changed stepwise for each of a plurality of light-emitting elements. Alternatively, a form in which ΔML is changed for each light-emitting element and a form in which ΔML is changed stepwise for each of a plurality of light-emitting elements may be combined. In this embodiment, ΔML23 at the center of the display region is set to 0, but it does not have to be 0. ΔML within the display region may also be constant.

Figure 8 is a diagram showing another example of the configuration of a light-emitting device according to one embodiment of the present invention. Figure 8(a) is a schematic cross-sectional view of a light-emitting device according to one embodiment of the present invention. In this embodiment, the light extraction structure is, for example, a microlens. The light extraction structure only needs to have a certain inclination angle with respect to the main surface of the insulating layer, and may be, in addition to a microlens, an aspherical microlens, a conical type, a cylindrical type, or a digital microlens.

In FIG. 8(a), the light-emitting element 3 on the substrate 5 is a light-emitting device having a reflective layer 6, a pixel separation layer 21 covering the edge of the reflective layer, an organic layer 7 containing a light-emitting material, a semi-transparent electrode 8, a protective layer 9, and a microlens 10. The portion of the reflective layer 6 that is not covered by the pixel separation layer 21 is the light-emitting region 22. The portion of the reflective layer 6 that is not covered by the pixel separation layer 21 is also called a pixel opening. The pixel separation layer 21 is a structure called a bank, and is an insulating layer. The reflective layer 6 and the semi-transparent electrode 8 are also called a lower electrode and an upper electrode, respectively, based on their arrangement positions. In addition, dummy pixels 3' are arranged outside the display area 1 in order to maintain the characteristics of the light-emitting element at the outermost periphery. The dummy pixels 3' may be formed in multiple columns and rows. The components of the dummy pixels may be the same as those of the light-emitting elements. The dummy pixels may have the same configuration as the light-emitting elements except that no current is supplied to them.

An insulating layer (not shown) may be provided on the substrate 5. The insulating layer may be formed of an oxide layer, a nitride layer, an organic layer, or the like. The insulating layer is also called a planarization layer because of its function. For example, it may have the role of reducing the effect that unevenness of a transistor formed on the substrate has on the electrodes.

The organic layer 7 may be composed of multiple layers. The multiple layers include a light-emitting layer, which has a light-emitting substance. A light-emitting layer that emits a single light-emitting color may be formed on the entire surface between the light-emitting elements. In addition, in order for the display device to display at least two or more colors, the display device may be configured such that light-emitting layers that emit different colors are laminated on the entire surface between the light-emitting elements, or a light-emitting layer that emits a different color for each light-emitting element is patterned. When the organic layer is composed of a light-emitting layer that emits white light, a color filter may be provided between the light-emitting elements and the microlenses.

The protective layer 9 is a layer that protects the light-emitting element, and may be composed of an inorganic layer such as silicon nitride, silicon oxynitride, silicon oxide, or aluminum oxide, or an organic layer such as acrylic resin, epoxy resin, or polyimide resin.

Light emitted from the light-emitting element is incident on the microlens 10. A planarization layer (not shown) may be provided between the microlens and the protective layer. The planarization layer may also serve as an adhesive layer. The planarization layer may be made of the same resin as the microlens.

8A shows the distance L from the semi-transparent electrode 8 to the microlens, the height h of the microlens, the radius φ of the microlens, the distance D between the apex of the microlens and the apex of the adjacent microlens, the refractive index _n2 of the protective layer, the refractive index _n1 of the microlens, and the external refractive index _n0 . The distance D does not have to be constant. More specifically, the distance D may be larger as it approaches the end of the display area, or may be smaller as it approaches the end of the display area. Here, in this embodiment, the height is the distance in the vertical direction of the paper.

Figure 8 (b) is a schematic cross-sectional view of a light-emitting device further having a color filter. A color filter 27 is further provided between the protective layer 9 and the microlens 10. The color filter is a filter that transmits a specific wavelength. For example, it may be a filter that transmits R out of RGB. As shown in Figure 8 (b), three types of color filters that transmit RGB respectively may be provided.

Figure 8 (c) is a schematic cross-sectional view of a light-emitting device having a different shape of color filter and microlens. Unlike the other embodiments, the microlens 10' has a convex shape that faces downward on the paper. The downward direction on the paper can also be said to be the direction from the semi-transparent electrode to the reflective layer. The space between the microlens 10' and the protective layer 9 may be an air gap or may be filled with another substance. A resin layer may be provided between the color filter 27 and the microlens 10'.

A protective glass 28 is provided on the color filter 27. An organic layer such as an adhesive layer may be provided between the protective glass 28 and the color filter 27. The protective glass 28 is also called an opposing substrate because it is positioned opposite the substrate 5.

Figure 8 (d) is a cross-sectional schematic diagram of a light-emitting device in which the optical interference distance of the light-emitting element is different for each emission color. On the reflective layer 6, an optical adjustment layer 29, a transparent electrode 30, an organic layer 7, a semi-transparent electrode 8, a protective layer 9, a filling layer 31, a color filter 27, and a microlens 10 are arranged. The color filters 27 are 27R, 27G, and 27B according to their transmission colors, which are red, green, and blue filters, respectively. The optical distance between the reflective layer 6 and the semi-transparent electrode 8 differs depending on the thickness of the optical adjustment layer 29. From the right in the figure, the light-emitting element strengthens blue, the light-emitting element strengthens green, and the light-emitting element strengthens red. The layer thickness of the optical adjustment layer of the first light-emitting element is greater than the layer thickness of the optical adjustment layer of the second light-emitting element. According to this embodiment, the optical interference distance can be set to be optimal for each emission color. In this embodiment, the optical adjustment layer under the transparent electrode is used to change the optical interference distance for each color, but the optical adjustment layer may be provided on the semi-transparent electrode. In addition, the thickness of the organic layer can be changed for each light-emitting element to optimize the optical interference distance for each light-emitting element. When changing the thickness of the organic layer for each light-emitting element, it is preferable to change the thickness of the organic layer on the reflective layer side of the light-emitting layer.

The wavelength range transmitted by the color filter may include the PL peak wavelength of the luminescent material. When the PL peak of the luminescent material has a first peak and a second peak smaller than the first peak, if priority is given to the brightness of the light emitting device, the first peak wavelength and the second peak wavelength may be included in the wavelength range transmitted by the color filter. When the PL peak of the luminescent material has a first peak and a second peak smaller than the first peak, if priority is given to the color purity of the light emitting device, only the first peak may be included in the wavelength range transmitted by the color filter.

Preferred for use in devices where brightness is important, such as head-mounted displays and AR glasses.

In this embodiment, the light-emitting element may have an electrode that supplies electric charge to the light-emitting material, and a pixel separation layer that covers one end of the electrode and the other end. The pixel separation layer is also called an insulating layer on the lower electrode. The insulating layer here refers to a layer separate from the insulating layer under the lower electrode. The pixel separation layer is also called a bank.

In a cross section perpendicular to the main surface of the substrate, the midpoint of the light extraction structure in a direction parallel to the main surface of the insulating layer and the midpoint between one end of the pixel separation layer and the other end may not overlap in a plan view.

The light-emitting device has a display area. The display area has a first area including a central portion of the display area, and a second area that is disposed outside the first area in a plan view.

The first region includes a third light-emitting element, and the second region includes a fourth light-emitting element, and the distance between the midpoint of the light extraction structure in the fourth light-emitting element and the midpoint between the end and the other end of the pixel isolation layer is greater than the distance between the midpoint of the light extraction structure in the third light-emitting element and the midpoint between the end and the other end of the pixel isolation layer. In other words, the misalignment between the light extraction structure and the bank opening is greater in the fourth light-emitting element.

[Configuration of Light-Emitting Device]
The light-emitting element is provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, a microlens, etc. may be provided on the cathode. When a color filter is provided, a planarizing layer may be provided between the protective layer. The planarizing layer may be made of acrylic resin, etc. The same applies when a planarizing layer is provided between the color filter and the microlens.

[substrate]
Examples of the substrate include quartz, glass, silicon wafer, resin, and metal. In addition, a switching element such as a transistor and wiring may be provided on the substrate, and an insulating layer may be provided thereon. As the insulating layer, any material can be used as long as it can form a contact hole so that wiring can be formed between the first electrode and the insulating layer, and insulation from wiring that is not connected can be ensured. For example, resin such as polyimide, silicon oxide, silicon nitride, etc. can be used.

[Light-emitting element]
The light-emitting element has a first electrode, a second electrode, and a light-emitting layer disposed between the first electrode and the second electrode and containing a light-emitting substance. The light-emitting layer may be an organic compound layer or an inorganic compound layer. The electrode may also serve as a reflective layer. The light-emitting substance may be fluorescent or phosphorescent.

[electrode]
A pair of electrodes can be used. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode. The electrodes may be formed across a plurality of light-emitting elements, or may be formed separately for each light-emitting element. For example, the anode may be formed separately for each light-emitting element, and the cathode may be formed across a plurality of light-emitting elements.

The material that constitutes the anode should have as large a work function as possible. For example, metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, silicon, and mixtures containing these metals, alloys combining these metals, and metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide can be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

One of these electrode materials may be used alone, or two or more may be used in combination. The anode may be composed of a single layer or multiple layers.

When used as a reflective layer, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys or laminates thereof can be used. The above materials can also function as a reflective layer without acting as an electrode. When used as a transparent electrode, transparent conductive oxide layers such as indium tin oxide (ITO) and indium zinc oxide can be used, but are not limited to these. Photolithography techniques can be used to form the electrodes. The reflective layer preferably has a reflectance of 70% or more at the emission wavelength. The reflective layer may also serve as an electrode.

On the other hand, the material for the cathode should have a small work function. Examples of such materials include alkali metals such as lithium, alkaline earth metals such as calcium, aluminum, titanium, manganese, silver, lead, and chromium, or mixtures containing these metals. Alternatively, alloys combining these metals can be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver can be used. Metal oxides such as indium tin oxide (ITO) can also be used. These electrode materials may be used alone or in combination of two or more types. The cathode may have a single layer or a multilayer structure. Among these, it is preferable to use silver, and it is even more preferable to use a silver alloy to reduce the aggregation of silver. As long as the aggregation of silver can be reduced, the ratio of the alloy is not important. For example, the ratio of silver to other metal may be 1:1, 3:1, etc.

The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective layer such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but DC and AC sputtering methods are more preferable because they provide good film coverage and make it easier to reduce resistance.

When used as a semi-transparent electrode, a metal that transmits part of the incident light and reflects part of it is used. A sufficiently thin metal layer can be formed to create a semi-transparent electrode. For example, a silver layer of about 10 nm can be formed to create a semi-transparent electrode.

[Organic layer]
The organic layer may be formed as a single layer or as multiple layers. When multiple layers are included, they may be called hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, or charge generation layer depending on their functions. The organic layer is mainly composed of organic compounds, but may also contain inorganic atoms or inorganic compounds. For example, it may contain copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc, or the like.

The organic layer may be an organic layer having a plurality of light-emitting layers. Any of the light-emitting layers may have a red light-emitting material, a green light-emitting material, or a blue light-emitting material, and it is also possible to obtain white light by mixing the respective light-emitting colors. Any of the light-emitting layers may have light-emitting materials of complementary colors, such as a blue light-emitting material and a yellow light-emitting material. The light-emitting material may be a material such as a fluorescent material, a phosphorescent material, or a delayed fluorescent material, or may be a quantum dot such as CdS or perovskite. Also, different colors may be emitted by changing the material or configuration contained in the light-emitting layer for each light-emitting element. A light-emitting layer may be formed for each light-emitting element. The organic compound layer may be disposed between the first electrode and the second electrode, or may be disposed in contact with the first electrode and the second electrode.

[Protective layer]
The protective layer is an insulating layer, and preferably contains an inorganic material that is transparent and has low permeability to oxygen and moisture from the outside. The protective layer can be made of inorganic materials such as silicon nitride (SiN), silicon oxynitride (SiON), silicon oxide (SiOx), aluminum oxide (Al ₂ O ₃ , etc.), and titanium oxide (TiO ₂ ). It may be provided directly on the cathode, or an organic resin layer may be provided between the cathode and the protective layer. The organic resin layer may be made of, for example, polyacrylate, polyimide, polyester, epoxy, etc.

Also, by bonding glass with a moisture absorbent on the cathode, it is possible to reduce the intrusion of water into the organic layer and reduce the occurrence of display defects. In another embodiment, a passivation film such as silicon nitride may be provided on the cathode to reduce the intrusion of water into the organic compound layer. For example, after forming the cathode, the cathode may be transported to another chamber without breaking the vacuum, and a silicon nitride film having a thickness of 2 μm may be formed by the CVD method to serve as a protective layer. A protective layer may be provided using the atomic deposition method (ALD method) after the film is formed by the CVD method. The material of the film formed by the ALD method is not limited, and may be silicon nitride, silicon oxide, aluminum oxide, etc. Silicon nitride may be further formed by the CVD method on the film formed by the ALD method. The film formed by the ALD method may have a smaller thickness than the film formed by the CVD method. Specifically, it may be 50% or less, or even 10% or less.

[Color filter]
A color filter may be provided on the protective layer. For example, a color filter taking into consideration the size of the organic light-emitting element may be provided on another substrate and then bonded to the substrate on which the organic light-emitting element is provided, or a color filter may be patterned on the protective layer described above using a photolithography technique. The color filter may be made of a polymer.

[Planarization layer]
A planarization layer may be provided between the color filter and the protective layer. The planarization layer is provided for the purpose of reducing unevenness of the layer below. It may also be called a resin layer without limiting the purpose. The planarization layer may be composed of an organic compound, and may be a low molecular weight or a high molecular weight, but is preferably a high molecular weight.

The planarization layer may be provided above and below the color filter, and may be made of the same or different materials. Specific examples include polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[Microlens]
The organic light-emitting device may have an optical member such as a microlens on its light-emitting side. The microlens may be made of acrylic resin, epoxy resin, or the like. The microlens may be intended to increase the amount of light extracted from the organic light-emitting device and control the direction of the extracted light. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, among the tangents to the hemisphere, there is a tangent that is parallel to the insulating layer, and the tangent and the hemisphere are the vertices of the microlens. The vertex of the microlens can be determined in the same manner in any cross-sectional view. In other words, among the tangents to the semicircle of the microlens in the cross-sectional view, there is a tangent that is parallel to the insulating layer, and the tangent and the semicircle are the vertices of the microlens.

It is also possible to define the midpoint of a microlens. In the cross section of the microlens, a line segment can be imagined from the point where an arc shape ends to the point where another arc shape ends, and the midpoint of this line segment can be called the midpoint of the microlens. The cross section for determining the vertex and midpoint may be a cross section perpendicular to the insulating layer.

Microlenses can be formed by adjusting the exposure and development processes. Specifically, a film (photoresist film) is formed from a material for forming the microlenses, and the photoresist film is exposed and developed using a mask with continuous gradation changes. As such a mask, it is possible to use a gray mask, or an area gradation mask that allows light irradiation with continuous gradations on the imaging surface by changing the density distribution of dots made of a light-shielding film that is below the resolution of the exposure device.

In addition, it is possible to adjust the lens shape by performing an etch-back process on the microlenses formed by the exposure and development process. The shape of the microlens only needs to have an inclined portion capable of refracting the emitted light, and it may be spherical or have an asymmetric cross-sectional shape.

[Counter substrate]
A counter substrate may be provided on the planarization layer. The counter substrate is called a counter substrate because it is provided at a position corresponding to the aforementioned substrate. The constituent material of the counter substrate may be the same as that of the aforementioned substrate. When the aforementioned substrate is a first substrate, the counter substrate may be a second substrate.

[Formation of organic layer]
The organic compound layers (such as a hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a charge generation layer) constituting the organic light emitting device according to one embodiment of the present invention are formed by the method described below.

The organic compound layer constituting the organic light-emitting device according to one embodiment of the present invention can be formed using a dry process such as vacuum deposition, ionization deposition, sputtering, plasma, etc. Alternatively to the dry process, a wet process can be used in which the compound is dissolved in an appropriate solvent and a layer is formed using a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

If a layer is formed by vacuum deposition or solution coating, crystallization is unlikely to occur and the layer has excellent stability over time. When forming a film by coating, the film can also be formed by combining with an appropriate binder resin.

Examples of the binder resin include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, urea resin, etc.

These binder resins may be used alone as homopolymers or copolymers, or two or more types may be mixed together. If necessary, known additives such as plasticizers, antioxidants, and ultraviolet absorbers may be used in combination.

[Pixel circuit]
The light emitting device may have a pixel circuit connected to the light emitting element. The pixel circuit may be an active matrix type that controls the emission of the first light emitting element and the second light emitting element independently. The active matrix type circuit may be a voltage programming circuit or a current programming circuit. The drive circuit has a pixel circuit for each pixel. The pixel circuit may have a light emitting element, a transistor that controls the emission luminance of the light emitting element, a transistor that controls the emission timing, a capacitance that holds the gate voltage of the transistor that controls the emission luminance, and a transistor for connecting to GND without going through the light emitting element.

The light-emitting device has a display region and a peripheral region arranged around the display region. The display region has a pixel circuit, and the peripheral region has a display control circuit. The mobility of the transistors constituting the pixel circuit may be smaller than the mobility of the transistors constituting the display control circuit.

The slope of the current-voltage characteristics of the transistors that make up the pixel circuit may be smaller than the slope of the current-voltage characteristics of the transistors that make up the display control circuit. The slope of the current-voltage characteristics can be measured by the so-called Vg-Ig characteristics.

The transistors that make up the pixel circuit are transistors that are connected to a light-emitting element, such as the first light-emitting element.

[Pixels]
An organic light emitting device includes a plurality of pixels, each of which includes sub-pixels that emit different colors, for example, each of which may emit RGB colors.

A pixel emits light in an area also called the pixel aperture. This area is the same as the first area. The pixel aperture may be 15 μm or less, or 5 μm or more. More specifically, it may be 11 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc.

The distance between subpixels may be 10 μm or less, specifically 8 μm, 7.4 μm, or 6.4 μm.

The pixels may have a known arrangement in plan view. For example, they may be a stripe arrangement, a delta arrangement, a pentile arrangement, or a Bayer arrangement. The shape of the subpixels in plan view may be any known shape. For example, they may be rectangular, quadrilaterals such as diamonds, or hexagons. Of course, any shape close to a rectangle, rather than an exact shape, is included in the rectangle. The shape of the subpixels and the pixel arrangement may be used in combination.

Example 1
Next, the specific effects of the present invention will be described using examples. In these examples, a monochromatic organic light-emitting device was used. Table 1 shows the microlens height h/D, the microlens radius Φ/D, and the height L2/D of the upper surface of the color filter normalized by the pixel pitch D.

As mentioned above, the effects of the present invention are not limited to monochrome or white, and color filters, etc. may also be provided separately.

Figure 9 is a diagram showing the relationship between the radiation angle and the relative light amount in the light-emitting layer, determined by ray tracing. As shown in the figure, in ray tracing for the configuration in Table 1, the maximum relative light amount was achieved at 10° to 15° in the front direction. In Example 1, the reflective layer was an Al electrode, the semi-transparent electrode was 15 nm thick MgAg, and the protective layer was a SiN film. The microlenses were formed using a material with a refractive index n = 1.5. Figure 10 shows the PL spectrum PL1 of the light-emitting material used in Example 1. The maximum peak wavelength of the PL spectrum was 523 nm.

The results of the study are shown in Table 2. In this example, the interference order m between the reflective layer and the light-emitting point described in formula (4) was set to 1, and the interference order m' from the light-emitting point to the semi-transparent electrode was set to 0. Comparative example D001 is configured such that under the above conditions, the interference peak resonance wavelength λ _on in the front direction coincides with λ _PL , and the interference peak resonance wavelength λ _off in the direction inclined with respect to the main surface of the substrate is located on the short wavelength side with respect to λ _PL . Examples D101 and D102 are configured such that the interference peak resonance wavelength λ _off in the direction inclined with respect to the main surface of the substrate is close to λ _PL under the conditions that λ _on is 545 nm and 552 nm, respectively. The relative radiant intensity in Table 2 is a value normalized by the radiance of the comparative example for the configurations without and with microlenses.

First, the characteristics of the organic light-emitting element without a microlens are compared. It can be seen that the interference conditions of D101 and D102, compared to D001, show that the EL spectrum peak intensity λ _EL (0) in the front direction without a microlens is shifted to the long-wave side with respect to λ _PL , and the relative radiant intensity is equal to or lower than 1 or 0.99. On the other hand, in the case of the microlens, D101 and D102 increase to 1.36 and 1.4, respectively, and the EL peak wavelength λ _EL is 529 nm and 530 nm, which is close to λ _PL = 523 nm. This is due to the components around Θeml, which have the highest contribution of the components refracted in the front direction at the inclined part of the microlens shown in FIG. 5(b). In D101 and D102, the difference between the interference peak resonance wavelength and the PL peak wavelength in the front direction, |λ _off - _{λ PL} |, is 22 nm and 29 nm, respectively, while the difference between the EL peak wavelength and the _PL peak wavelength, |λ _EL - λ _PL |, is 6 nm and 7 nm, respectively. Thus, in an organic light-emitting element having a light extraction structure, the radiance in the front direction can be increased by adjusting the optical interference of the organic EL element so that |λ _EL - λ PL | is smaller than |λ _off - _{λ PL} |.

Example 2
Example 2 is the same as Example 1, except that the spectral shape of the luminescent material is double-peaked, which means that the emission spectrum has a first peak and a second peak.

Table 3 shows λ _PL , λ _on , λ _off , and front radiation intensity in Example 2. The difference between λ _PL , λ _EL , and λ _on under each condition is shown. Comparative Example D002 is configured under the above conditions such that the front interference peak resonance wavelength λ _on is equal to λ _PL , and the interference peak resonance wavelength λ _off in the direction tilted with respect to the substrate main surface is located on the short wave side with respect to λ _PL . Examples D103 and D104 are configured under the conditions of λ _on being 545 nm and 552 nm, respectively, and the interference peak resonance wavelength λ _off in the direction tilted with respect to the substrate main surface is close to λ _PL . The relative radiation intensity in Table 3 is a value normalized by the radiance of D002.

First, a comparison is made with a configuration without a microlens. The interference conditions of D103 and D104 with respect to D002 are such that the EL spectrum peak intensity λ _EL (0) in the front direction without a microlens is shifted to the long wavelength side of 542 nm and 549 nm, respectively, compared to λ _PL = 523 nm, and the relative radiance is reduced to 1 and 0.98 or less. On the other hand, when a microlens is present, the relative radiance of D103 and D104 increases to 1.4 and 1.45, respectively. In addition, the EL peak wavelength λ _EL is 524 nm for both, which is close to λ _PL = 523 nm. This is due to the components around Θeml, which have the highest contribution of the components refracted in the front direction at the inclined part of the microlens shown in FIG. 5(b). In D103 and D104, the difference |λ _off - λ _PL | between the interference peak resonance wavelength λ _on and the PL peak wavelength in the front direction was 22 nm and 29 nm, respectively, while the difference |λ _EL - λ _PL | between the EL peak wavelength and the PL peak wavelength was both 1 nm. It was found that the present invention is also useful for light-emitting dopants having a PL spectrum shape with a second peak such as PL2.

Example 3
Example 3 is the same as Example 2, except that the interference order m between the reflective layer and the light emitting point is set to 0, and the semi-transparent electrode is set to 23 nm. Table 4 explains the results of the study on Example 3.

Comparative example D003 is configured under the above conditions to match the front interference peak resonance wavelength λ _on with λ _PL , and the interference peak resonance wavelength λ _off in the direction tilted with respect to the substrate main surface is located on the short wavelength side with respect to λ _PL . Example D105 is configured under the condition that λ _on is 539 nm, and the interference peak resonance wavelength λ _off in the direction tilted with respect to the substrate main surface is 524 nm, close to λ _PL = 523 nm. The relative radiant intensity in Table 4 is a value normalized by the radiance of D003.

First, a comparison is made with a configuration without a microlens. The interference conditions of D105 compared to D003 are such that the EL spectrum peak intensity λ _EL (0) in the front direction without a microlens is shifted to the long wavelength side, 528 nm, compared to λ _PL = 523 nm. The relative radiance is also reduced to 0.9. On the other hand, in the case of the microlens, the relative radiance of D105 increases to 1.36. The EL peak wavelength λ _EL is 524 nm for both, which is close to λ _PL = 523 nm. This is due to the components around Θeml, which have the highest contribution of the components refracted in the front direction at the inclined part of the microlens shown in FIG. 5(b). In D105, the difference |λ _off -λ _PL | between the interference peak resonance wavelength λ _on and the PL peak wavelength in the front direction is 16 nm, while the difference |λ _EL -λ _PL | between the EL peak wavelength and the PL peak wavelength is 1 nm. It has been found that the present invention can be effective even when the order of interference m between the reflective layer and the light emitting point is set to zero.

Example 4
Example 4 is the same as Example 2, except that the interference order m' between the semitransparent electrode and the light emitting point is set to 1. Table 5 explains the results of the study on Example 4.

Comparative example D004 is configured under the above conditions such that the interference peak resonance wavelength λ _on in the front direction is equal to λ _PL , and the interference peak resonance wavelength λ _off in the direction tilted with respect to the substrate main surface is located on the short wavelength side with respect to λ _PL . Example D106 is configured under the condition that λ _on is 538 nm, and the interference peak resonance wavelength λ _off in the direction tilted with respect to the substrate main surface is 520 nm, close to λ _PL = 523 nm. The relative radiant intensity in Table 5 is a value normalized by the radiance of D004.

First, a comparison is made with a configuration without a microlens. The interference conditions of D106 with respect to D004 are such that the EL spectrum peak intensity λ _EL (0) in the front direction without a microlens is shifted to the long wavelength side, 528 nm, compared to λ _PL = 523 nm. The relative radiance is also reduced to 0.84. On the other hand, in the case of the microlens, the relative radiance of D105 increases to 1.13. The EL peak wavelength λ _EL is also 524 nm, which is close to λ _PL = 523 nm. This is due to the components around Θeml, which have the highest contribution of the components refracted in the front direction at the inclined surface of the microlens shown in FIG. 5(b). In D106, the difference |λ _off -λ _PL | between the interference peak resonance wavelength λ _on and the PL peak wavelength in the front direction is 15 nm, while the difference |λ _EL -λ _PL | between the EL peak wavelength and the PL peak wavelength is 1 nm. It has been found that the present invention can be effective even when the interference order m between the semi-transparent electrode and the light-emitting point is set to 1.

The above shows that the effect of the present invention does not depend on the shape of the PL spectrum of the emitting dopant or the interference order.

[Use of the organic light-emitting device according to one embodiment of the present invention]
The organic light-emitting device according to an embodiment of the present invention can be used as a component of a display device or a lighting device, and can also be used as an exposure light source for an electrophotographic image forming device, a backlight for a liquid crystal display device, a light-emitting device having a white light source and a color filter, etc.

The display device may be an image information processing device that has an image input unit that inputs image information from an area CCD, a linear CCD, a memory card, etc., has an information processing unit that processes the input information, and displays the input image on the display unit.

The display unit of the imaging device or inkjet printer may have a touch panel function. The driving method of this touch panel function is not particularly limited and may be an infrared method, a capacitance method, a resistive film method, or an electromagnetic induction method. The display device may also be used in the display unit of a multifunction printer.

Next, the display device according to this embodiment will be described with reference to the drawings.

The light-emitting element according to one embodiment of the present invention may be used in an image forming apparatus. The image forming apparatus has a photoconductor, an exposure light source, a developing unit, a charging unit, a transfer unit, a transport roller, and a fixing unit.

Light is irradiated from the exposure light source, and an electrostatic latent image is formed on the surface of the photoconductor. This exposure light source has the organic light-emitting element according to the present invention. The developing unit has toner, etc. The charging unit charges the photoconductor. The transfer device transfers the developed image to a recording medium. The transport unit transports the recording medium. The recording medium is, for example, paper. The fixing unit fixes the image formed on the recording medium.

The exposure light source may have multiple light-emitting sections arranged on a long substrate. The row direction in which the organic light-emitting elements are arranged may be the axial direction of the photoconductor. This row direction is the same as the direction of the axis about which the photoconductor rotates. This direction can also be called the long axis direction of the photoconductor.

The light-emitting units may be arranged in a first column and a second column such that the light-emitting units are alternately arranged in the column direction. The first column and the second column are arranged at different positions in the row direction.

The first column may have multiple light-emitting units arranged at intervals. The second column has light-emitting units at positions corresponding to the intervals between the light-emitting units in the first column. That is, multiple light-emitting units may also be arranged at intervals in the row direction. The light-emitting elements may be arranged, for example, in a grid pattern, a houndstooth pattern, or a checkerboard pattern.

Figure 11 is a schematic diagram showing an example of a light-emitting device according to this embodiment. The display device 1000 may have a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are connected to flexible printed circuits FPCs 1002 and 1004. Transistors are printed on the circuit board 1007. The battery 1008 may not be provided if the display device is not a portable device, and may be provided in a different position even if the display device is a portable device. The display panel includes a light-emitting device.

The display device according to this embodiment may have a color filter having red, green, and blue colors. The color filters may be arranged such that the red, green, and blue colors are arranged in a delta arrangement.

The display device according to this embodiment may be used as a display unit of a mobile terminal. In this case, it may have both a display function and an operation function. Examples of the mobile terminal include mobile phones such as smartphones, tablets, and head-mounted displays. It may have a display control unit that controls the image to be displayed.

The light emitting device according to this embodiment may be used in the display section of an imaging device having an optical section with multiple lenses and an imaging element that receives light that has passed through the optical section. The imaging device may have a display section that displays information acquired by the imaging element. The display section may be a display section exposed to the outside of the imaging device, or may be a display section disposed within the viewfinder. The imaging device may be a digital camera or a digital video camera.

FIG. 12(a) is a schematic diagram showing an example of an imaging device according to this embodiment. The imaging device 1100 may have a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may have a light-emitting device according to this embodiment. In this case, the display device may display not only the image to be captured, but also environmental information, imaging instructions, etc. The environmental information may include the intensity of external light, the direction of external light, the speed at which the subject moves, the possibility that the subject will be blocked by an obstruction, etc.

The optimal timing for capturing an image is very short, so it is better to display information as soon as possible. Therefore, it is preferable to use the organic light-emitting device of the present invention. This is because organic light-emitting elements have a fast response speed. Organic light-emitting devices can be used more preferably than liquid crystal display devices, which require high display speed.

The imaging device 1100 has an optical section (not shown). The optical section has multiple lenses, which form an image on an imaging element housed in a housing 1104. The focus of the multiple lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically. The imaging device may be called a photoelectric conversion device. Rather than capturing images sequentially, photoelectric conversion devices can include imaging methods such as a method of detecting the difference from the previous image and a method of cutting out an image that is constantly recorded.

FIG. 12(b) is a schematic diagram showing an example of an electronic device according to this embodiment. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type reaction unit. The operation unit may be a biometric recognition unit that recognizes a fingerprint and performs unlocking, etc. An electronic device having a communication unit can also be called a communication device. The electronic device may further have a camera function by including a lens and an image sensor. An image captured by the camera function is displayed on the display unit. Examples of the electronic device include a smartphone and a laptop computer.

Figure 13 is a schematic diagram showing an example of a light-emitting device according to this embodiment. Figure 13(a) shows a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. The light-emitting device according to this embodiment may be used for the display unit 1302.

It has a frame 1301 and a base 1303 that supports a display unit 1302. The base 1303 is not limited to the form shown in FIG. 4(a). The bottom side of the frame 1301 may also serve as the base.

Furthermore, the frame 1301 and the display unit 1302 may be curved. The radius of curvature may be 5000 mm or more and 6000 mm or less.

Figure 13 (b) is a schematic diagram showing another example of the light-emitting device according to this embodiment. The display device 1310 in Figure 13 (b) is configured to be bendable, and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may have the light-emitting device according to this embodiment. The first display unit 1311 and the second display unit 1312 may be a single display unit without any joints. The first display unit 1311 and the second display unit 1312 can be separated by the bending point. The first display unit 1311 and the second display unit 1312 may each display different images, or the first and second display units may display a single image.

The light-emitting device according to the present invention may be used in a lighting device. The lighting device may have a housing, a light source, a circuit board, an optical film, and a light diffusion section. The light source may have the light-emitting device according to this embodiment. The optical filter may be a filter that improves the color rendering of the light source. The light diffusion section can effectively diffuse the light of the light source, such as for lighting up, and deliver the light over a wide range. The optical filter and the light diffusion section may be provided on the light emission side of the lighting. If necessary, a cover may be provided on the outermost part.

The lighting device is, for example, a device that illuminates a room. The lighting device may emit white light, daylight white light, or any other color from blue to red. It may have a dimming circuit that adjusts the light intensity. The lighting device may have an organic light-emitting element of the present invention and a power supply circuit connected thereto. The power supply circuit is a circuit that converts AC voltage into DC voltage. Furthermore, white has a color temperature of 4200K, and daylight white has a color temperature of 5000K. The lighting device may have a color filter.

The lighting device according to this embodiment may also have a heat dissipation section. The heat dissipation section dissipates heat from within the device to the outside, and examples of the heat dissipation section include metals with high specific heat, liquid silicon, etc.

The light-emitting device according to the present invention may be used in a moving object such as an automobile. The automobile has tail lamps, which are an example of a lamp. The automobile may have tail lamps and may be configured to turn on the tail lamps when braking or the like is performed.

The tail lamp may have the light-emitting device according to this embodiment. The tail lamp may have a protective member that protects the organic light-emitting element. The protective member may be made of any material as long as it has a relatively high strength and is transparent, but it is preferable that the protective member is made of polycarbonate or the like. Polycarbonate may be mixed with a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like.

The automobile may have a body and windows attached to it. The windows may be transparent displays, provided they are not windows for viewing the front and rear of the automobile. The transparent displays may have the organic light-emitting device according to this embodiment. In this case, the constituent materials of the electrodes and the like of the organic light-emitting element are made of transparent materials.

The moving body according to this embodiment may be a ship, an aircraft, a drone, or the like. The moving body may have a body and a lamp provided on the body. The lamp may emit light to indicate the position of the body. The lamp has an organic light-emitting element according to this embodiment.

With reference to FIG. 14, an application example of the display device of each of the above-mentioned embodiments will be described. The display device can be applied to a system that can be attached as a wearable device such as smart glasses, HMD, or smart contacts. An imaging and display device used in such an application example has an imaging device capable of photoelectrically converting visible light, and a display device capable of emitting visible light.

Figure 14 (a) illustrates glasses 1600 (smart glasses) according to one application example. An imaging device 1602 such as a CMOS sensor or SPAD is provided on the front side of a lens 1601 of the glasses 1600. In addition, a display device according to each of the above-mentioned embodiments is provided on the back side of the lens 1601.

The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the image capture device 1602 and the display device according to each embodiment. The control device 1603 also controls the operation of the image capture device 1602 and the display device. The lens 1601 is formed with an optical system for focusing light on the image capture device 1602.

Figure 14 (b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612, which is equipped with an imaging device equivalent to the imaging device 1602 and a display device. The lens 1611 is formed with an optical system for projecting light emitted from the imaging device in the control device 1612 and the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power source that supplies power to the imaging device and the display device, and controls the operation of the imaging device and the display device. The control device may have a line of sight detection unit that detects the line of sight of the wearer. Infrared light may be used to detect the line of sight. The infrared light emission unit emits infrared light toward the eyeball of a user gazing at a displayed image. An imaging unit having a light receiving element detects the reflected light of the emitted infrared light from the eyeball, thereby obtaining an image of the eyeball. By having a reduction means for reducing light from the infrared light emission unit to the display unit in a planar view, deterioration of image quality is reduced.

The user's line of sight with respect to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be used for line of sight detection using an image of the eyeball. As an example, a line of sight detection method based on the Purkinje image formed by reflection of irradiated light on the cornea can be used.

More specifically, gaze detection processing is performed based on the pupil-corneal reflex method. Using the pupil-corneal reflex method, a gaze vector that represents the direction (rotation angle) of the eyeball is calculated based on the pupil image and Purkinje image contained in the captured image of the eyeball, thereby detecting the user's gaze.

A display device according to one embodiment of the present invention may have an imaging device having a light receiving element, and may control the display image of the display device based on user line-of-sight information from the imaging device.

Specifically, the display device determines a first field of view area on which the user gazes and a second field of view area other than the first field of view area based on the line of sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be received from an external control device. In the display area of the display device, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than the first field of view area.

The display area has a first display area and a second display area different from the first display area, and an area with a high priority is determined from the first display area and the second display area based on line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the display device, or may be received from an external control device. The resolution of the high priority area may be controlled to be higher than the resolution of areas other than the high priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

AI may be used to determine the first field of view area and areas with high priority. The AI may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from the image of the eyeball, using as training data an image of the eyeball and the direction in which the eyeball in the image was actually looking. The AI program may be possessed by the display device, the imaging device, or an external device. If possessed by an external device, it is transmitted to the display device via communication.

When display control is based on visual detection, it is preferably applicable to smart glasses that further include an imaging device that captures images of the outside world. The smart glasses can display captured external information in real time.

As explained above, by using a device using the organic light-emitting element according to this embodiment, it is possible to achieve a display with good image quality and stability even over long periods of time.

REFERENCE SIGNS LIST 1 display area 2 edge of display area 3 light emitting element 3' dummy pixel 4 optical member 5 substrate 6 reflective layer 7 organic layer 8 semi-transparent electrode 9 protective layer 10 microlens 11 light emitting point 12 emitted light 13 inclined portion 14 distance from center of pixel to light emitting position 15 light emitting area 16 light extraction surface 17 inclination angle 18 light emitting area 19 light extraction surface 20 light emitting area emitting light toward the front direction 21 pixel separation layer 22 light emitting area 23 to 26 ΔML
27 Color filter 28 Protective glass 29 Optical adjustment layer 30 Transparent electrode 31 Filling layer 1000 Display device 1001 Upper cover 1002 Flexible printed circuit 1003 Touch panel 1004 Flexible printed circuit 1005 Display panel 1006 Frame 1007 Circuit board 1008 Battery 1009 Lower cover 1100 Imaging device 1101 Viewfinder 1102 Rear display 1103 Operation unit 1104 Housing 1200 Electronic device 1201 Display unit 1202 Operation unit 1203 Housing 1300 Display device 1301 Frame 1302 Display unit 1303 Base 1310 Display device 1311 First display unit 1312 Second display unit 1313 Housing 1314 Bend point 1600 Smart glasses 1601 Lens 1602 Imaging device 1603 Control device 1610 Smart glasses 1611 Lens 1612 Control device

Claims (29)

A light emitting device comprising: an insulating layer; a light emitting element including a light emitting material and having a resonator structure, the light emitting element being disposed on a main surface of the insulating layer; and a light extraction structure being provided on the light emitting element, the light emitting material having a first peak having a wavelength λ _PL in a visible light region in a PL spectrum,
a resonant peak wavelength λ _on of an interference spectrum that intensifies light emitted in a direction perpendicular to the main surface, a peak wavelength λ _EL of EL emission emitted via the light extraction structure, and the λ _PL satisfy the following formula (1):
|λ _EL -λ _PL | < |λ _on -λ _PL | (1)
However, λ _PL < λ _EL < λ _on . The light-emitting device according to claim 1, characterized in that in the PL spectrum, the first peak is a maximum intensity peak in the visible light region. 3. The light emitting device according to claim 1, wherein a PL peak wavelength λ _PL is a wavelength of a peak in the PL spectrum that is closest to the λ _on . A light emitting device comprising: an insulating layer; a light emitting element including a light emitting material and having a resonator structure, the light emitting element being disposed on a main surface of the insulating layer; and a light extraction structure being provided on the light emitting element, the light emitting material having a PL spectrum having a first peak having a wavelength λ _PL in a visible light region,
a resonant peak wavelength λ _on of an interference spectrum that intensifies light emitted in a direction perpendicular to the main surface in the resonator structure, a resonant peak wavelength λ _off of an interference spectrum that intensifies light emitted in a direction perpendicular to the main surface due to refraction in the light extraction structure, and the λ _PL satisfy the following formula (2):
|λ _off -λ _PL | < |λ _on -λ _PL | (2) The light emitting device according to claim 4 , wherein the PL spectrum of the luminescent substance has a second peak having a wavelength λ _PL2 and a lower emission intensity than the first peak, and satisfies the following formula (3):
|λ _off −λ _PL | ≦ |λ _on −λ _PL2 | (3) The light-emitting device according to claim 5, characterized in that in the PL spectrum, the first peak is the maximum intensity peak in the visible light region, and the second peak is the peak with the second highest intensity after the first peak. 7. The light emitting device according to claim 4, wherein a PL peak wavelength λ _PL is a wavelength of a peak in the PL spectrum that is closest to the λ _on . 8. The light emitting device according to claim 3, wherein the λ _on is longer than the PL peak wavelength λ _PL . Said λ _On and the λ _P.L. 9. The light emitting device according to claim 1, wherein the difference between the first peak and the second peak is equal to or smaller than the full width at half maximum of the first peak. Said λ _On and the λ _PL2 The light emitting device according to claim 5 , wherein the difference between the first peak and the second peak is equal to or smaller than the full width at half maximum of the second peak. the light extraction structure has an inclined portion inclined with respect to the main surface,
11. The light emitting device according to claim 1, wherein the inclined portion refracts light traveling in a direction inclined with respect to the main surface in a direction perpendicular to the main surface. 12. The light emitting device according to claim 11 , wherein the inclination angle of the inclined portion with respect to the main surface is equal to or greater than 9 degrees and equal to or less than 60 degrees. The light emitting device according to claim 11 or 12, characterized in that the light refracted in the forward direction at the inclined portion of the light extraction structure has a radiation angle Θeml with respect to the main surface in the light emitting layer of the light emitting element that is greater than 0° and less than 30 °. The light emitting device according to any one of claims 11 to 13, characterized in that the light refracted in the forward direction at the inclined portion of the light extraction structure has a radiation angle Θeml with respect to the main surface in the light emitting layer of the light emitting element of 5° or more and 20° or less. The light-emitting element has an electrode for supplying electric charge to the light-emitting material,
a pixel separation layer covering one end and the other end of the electrode;
15. The light-emitting device according to claim 1, wherein in a cross section perpendicular to the main surface of the insulating layer, a midpoint of the light extraction structure in a direction parallel to the main surface and a midpoint between an end of the pixel separation layer and the other end do not overlap in a planar view. The display area includes a first area including a center portion of the display area and a second area disposed outside the first area,
the first region includes a third light emitting element, and the second region includes a fourth light emitting element;
The light-emitting device described in claim 15, characterized in that the distance between the midpoint of the light extraction structure in the fourth light-emitting element and the midpoint between the end of the pixel isolation layer and the other end is greater than the distance between the midpoint of the light extraction structure in the third light-emitting element and the midpoint between the end of the pixel isolation layer and the other end. The light-emitting element has an electrode for supplying electric charge to the light-emitting material,
a pixel separation layer covering one end and the other end of the electrode;
a light-emitting portion having the light-emitting material,
In a cross section perpendicular to a principal surface of the insulating layer, when a midpoint of the light extraction structure in a direction parallel to the principal surface and a midpoint between an end of the pixel separation layer and the other end do not overlap in a plan view,
6. The light emitting device according to claim 4, wherein the optical path length of the λ _off is a distance between the light emitting portion and a curved surface of the light extraction structure that is farther from the light emitting portion in the cross section. 18. The light emitting device according to claim 1, further comprising a second light emitting element having a different resonator structure from the light emitting element, the second light emitting element enhancing light of a different wavelength from the light emitting element. The light-emitting device of claim 18, characterized in that the light-emitting element has a first optical adjustment layer, the second light-emitting element has a second optical adjustment layer, and the layer thickness of the first optical adjustment layer is smaller than the layer thickness of the second optical adjustment layer. 20. The light emitting device according to claim 1, further comprising a second light emitting element different from the light emitting element, the second light emitting element not satisfying the formula (1). The light-emitting device according to claim 4, characterized in that it has a second light-emitting element different from the light-emitting element, and the second light-emitting element does not satisfy the formula (2). the emission spectrum of the luminescent material has a first full width at half maximum;
the second light-emitting element has a second light-emitting material;
the emission spectrum of the second luminescent material has a second full width at half maximum;
22. The light emitting device according to any one of claims 18 to 21 , wherein the second full width at half maximum of the second luminescent material is greater than the first full width at half maximum. 23. The light emitting device of claim 22 , wherein the second emissive material is a phosphorescent emissive material. 24. The light emitting device according to claim 1 , wherein the light emitting substance of the light emitting element is a fluorescent material. a second light-emitting element different from the light-emitting element, and a second light-extraction structure different from the light-extraction structure and into which light from the second light-emitting element is incident,
25. The light-emitting device according to claim 1, characterized in that the distance in a direction parallel to the main surface between the midpoint of the light-emitting region of the light-emitting element and the midpoint of the light extraction structure in a cross section perpendicular to the main surface is greater than the distance in a direction parallel to the main surface between the midpoint of the light-emitting region of the second light-emitting element and the midpoint of the second light extraction structure in a cross section perpendicular to the main surface. a third light-emitting element different from the second light-emitting element, and a third light-extraction structure different from the second light-extraction structure and into which light from the third light-emitting element is incident,
The light-emitting device described in claim 25, characterized in that the distance in a direction parallel to the main surface between the midpoint of the light-emitting region of the second light-emitting element and the midpoint of the second light extraction structure in a cross section perpendicular to the main surface is greater than the distance in a direction parallel to the main surface between the midpoint of the light-emitting region of the third light-emitting element and the midpoint of the third light extraction structure in a cross section perpendicular to the main surface. A display device comprising: a light-emitting device according to claim 1 ; and a display control unit connected to the light-emitting device. an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image captured by the image sensor;
An imaging device, comprising: the display unit comprising the light-emitting device according to claim 1 . 27. An electronic device comprising: a display portion having the light-emitting device according to claim 1; a housing in which the display portion is provided; and a communication portion provided in the housing for communicating with an outside.

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