WO2015155925A1 - Planar light emitting body and illumination device - Google Patents

Abstract

　A planar light emitting body (100) is provided with: a light-transmissive substrate (110); a first electrode layer (121) and a second electrode layer (123), which are light-transmissive and layered in the stated order over the substrate (110); a light-emitting unit (122) provided between the first electrode layer (121) and the second electrode layer (123), the light-emitting unit (122) emitting light according to a first voltage applied between the first electrode layer (121) and the second electrode layer (123); and a variable reflectivity unit (130) having a pair of electrode layers and having variability in light reflectivity and light-transmission according to a second voltage applied between the pair of electrode layers, one of the pair of electrode layers being the second electrode layer (123).

Description

Planar light emitter and lighting device

The present invention relates to a flat light emitter including an organic EL (Electro-Luminescence) element, and a lighting device including the flat light emitter.

Conventionally, a display device provided with an organic EL element and an electrochromic element is known (see, for example, Patent Document 1). The electrochromic element is an element in which the light transmittance, the absorptivity, and the reflectance change in accordance with the applied voltage.

For example, the display device described in Patent Document 1 includes an organic EL element provided on a substrate, a planarizing film provided on the organic EL element, and an electrochromic element provided on the planarizing film. . Thereby, visibility can be improved by performing light transmittance control according to the light emission state of an organic EL element.

JP, 2013-003480, A

However, the above-described conventional display device has a problem that the light extraction efficiency of light emitted from the organic EL element, that is, the light emission efficiency is low.

Therefore, the present invention provides a flat light emitter and a lighting device capable of adjusting the reflectance and the transmittance and having high luminous efficiency.

In order to solve the above problems, a flat light-emitting body according to an aspect of the present invention includes a light-transmitting substrate, and a light-transmitting first electrode layer and a second electrode sequentially stacked above the substrate. Layer, a light emitting unit provided between the first electrode layer and the second electrode layer, which emits light according to a first voltage applied between the first electrode layer and the second electrode layer, and a pair of electrode layers A light reflective variable unit having variable light reflectivity and light transparency according to a second voltage applied between the pair of electrode layers, one of the pair of electrode layers being It is an electrode layer.

According to the present invention, it is possible to provide a flat light emitter and a lighting device whose reflectance and transmittance can be adjusted and whose luminous efficiency is high.

FIG. 1A is a view showing an example of use of a lighting device according to an embodiment of the present invention. FIG. 1B is a view showing a usage example of the lighting device according to the embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the illumination device according to the embodiment of the present invention. FIG. 3A is a plan view showing an arrangement example of the terminal portions of the flat light emitter according to the embodiment of the present invention. FIG. 3B is a partially exploded perspective view showing an arrangement example of the terminal portions of the flat light emitter according to the embodiment of the present invention. FIG. 3C is a plan view showing another example of arrangement of the terminal portions of the flat light emitter according to the embodiment of the present invention. FIG. 4 is a cross-sectional view showing the configuration of the flat light emitter according to the embodiment of the present invention. FIG. 5 is a diagram showing a spectrum of light emitted by the light emitting unit of the flat light emitter according to the embodiment of the present invention. FIG. 6 is a view showing an example of the material and film thickness of each layer of the light reflectivity variable unit of the flat light emitter according to the embodiment of the present invention. FIG. 7A is a view showing the relationship between the optical distance of the light reflective variable unit of the flat light emitter according to the embodiment of the present invention and the angular dependence of the emission color in the reflection state. FIG. 7B is a view showing the relationship between the optical distance of the light reflective variable unit of the flat light emitter according to the embodiment of the present invention and the angular dependence of the light emission color in the transmission state. FIG. 8 is a cross-sectional view showing the configuration of a flat light emitter according to a first modification of the embodiment of the present invention. FIG. 9 is a cross-sectional view showing a part of the configuration of a flat light emitter according to Modification 2 of the embodiment of the present invention.

(Findings that formed the basis of the present invention)
The inventors have found that the following problems occur with the display described in the "Background" section.

In the conventional display device, when the electrochromic element is in a reflection state, light emitted from the organic EL element is reflected by the electrochromic element and emitted from the light emitting surface side. At this time, the reflected light of the light emitted from the organic EL element is emitted from the light emitting surface after passing through the flattening film twice. Therefore, the light extraction loss is large due to the difference in refractive index between the layers, and the light emission efficiency is degraded.

In order to solve such a problem, a flat light-emitting body according to an aspect of the present invention includes a light-transmitting substrate, and a light-transmitting first electrode layer and a light-transmitting first electrode layer sequentially stacked above the substrate. A light emitting unit provided between the two electrode layers, the first electrode layer and the second electrode layer, and emitting light according to a first voltage applied between the first electrode layer and the second electrode layer; and a pair of electrode layers A light reflective variable unit having variable light reflectivity and light transparency according to a second voltage applied between the pair of electrode layers, one of the pair of electrode layers being a second electrode layer .

Thereby, the reflectance and the transmittance can be adjusted, and the light emission efficiency can be increased.

Hereinafter, a flat light emitter and a lighting apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a preferable specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangements of components, connection configurations and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims indicating the highest concept of the present invention are described as optional components.

Further, each drawing is a schematic view, and is not necessarily illustrated exactly. Moreover, in each figure, the same code | symbol is attached | subjected about the same structural member.

Embodiment
[Overview of lighting device]
First, an outline of a lighting device according to the present embodiment will be described using FIGS. 1A and 1B. FIG. 1A and FIG. 1B are figures which show the usage example of the illuminating device 10 which concerns on this Embodiment.

Lighting device 10 according to the present embodiment has four operation modes. Specifically, the four operation modes are the "transmission and extinction mode", the "transmission and illumination mode", the "reflection and extinction mode" and the "reflection and illumination mode".

The illumination device 10 according to the present embodiment has an illumination function, a transmission function, and a reflection (mirror) function, and thus can be used, for example, as a window or a window of a building such as a skylight. Alternatively, the lighting device 10 can also be used as a window of a transportation vehicle such as a car.

For example, when the lighting device 10 is used as a skylight, it is possible to take outside light such as sunlight into the room in the daytime “transmission mode” in the daytime, and can be used as lighting at night. In addition, in the "reflection mode" in the daytime, sunlight and the like can be prevented from entering the room, and heat insulation is also excellent.

For example, as shown to (a) of FIG. 1A, and (a) of FIG. 1B, the case where the users 20 and 30 are located in the both sides of the illuminating device 10 is assumed. In addition, in the example shown to (a) of FIG. 1A and (a) of FIG. 1B, the surface by the side of the user 30 of the illuminating device 10 can change light reflectivity and light transmittance.

When the lighting device 10 operates in the "transmission and extinguishing mode" ((b) in FIG. 1A), the user 20 and the user 30 can see each other. That is, in the “transmission and extinction mode”, external light can be transmitted from one surface of the lighting device 10 to the other surface. At this time, the illumination device 10 does not emit the illumination light to the outside.

Moreover, when the illuminating device 10 operate | moves by "transmission lighting mode" ((c) of FIG. 1A), the illuminating device 10 emits illumination light to both sides. That is, the lighting device 10 can illuminate both the user 20 and the user 30.

At this time, although it depends on the intensity of the illumination light from the illumination device 10, etc., the user 30 is visible from the user 20. That is, in the “transmission lighting mode”, the illumination device 10 can emit the illumination light to the outside and simultaneously transmit the external light from one surface of the illumination device 10 to the other surface.

Moreover, when the illuminating device 10 operate | moves in "reflection OFF mode" ((b) of FIG. 1B), the user 20 and the user 30 can not mutually visually recognize. The user 20 can view the mirror image 21 of himself / herself instead of the user 30 as shown in FIG. 1B (b). That is, the light incident from the user 20 side is reflected by the lighting device 10.

Thus, in the "reflection off mode", external light incident from one surface of the lighting device 10 is reflected by the other surface. At this time, the illumination device 10 does not emit the illumination light to the outside.

Moreover, when the illuminating device 10 operate | moves in "reflection lighting mode" ((c) of FIG. 1B), the illuminating device 10 emits illumination light to one side. In the example shown to FIG. 1B, illumination light is irradiated only to the user 20 side. This is because the illumination light emitted by the illumination device 10 is reflected by the surface on the user 30 side.

Thus, the user 20 and the user 30 can not see each other. The user 20 can view the mirror image 21 of itself as shown in (c) of FIG. 1B, although it depends on the intensity of the illumination light from the illumination device 10 instead of the user 30.

As mentioned above, lighting installation 10 concerning this embodiment can control independently "transmission" and "reflection" and "lighting out" and "lighting", respectively.

[Configuration of lighting device]
Then, the structure of the illuminating device 10 which concerns on this Embodiment is demonstrated using FIG. FIG. 2 is a view showing the configuration of the lighting apparatus 10 according to the present embodiment.

As shown in FIG. 2, the lighting device 10 includes a flat light emitter 100 and a power supply circuit 200. First, the detailed configuration of the flat light emitter 100 will be described.

[Plane light emitter]
The planar light emitter 100 includes a substrate 110, an organic EL element 120, and an electrochromic element 130, as shown in FIG.

The substrate 110 is a light transmitting substrate. For example, the substrate 110 is a transparent substrate that transmits at least a portion of visible light. The main surface of the substrate 110 opposite to the main surface on which the organic EL element 120 is provided is the light emitting surface of the flat light emitter 100.

For example, the substrate 110 is a glass substrate such as non-alkali glass, soda glass, non-fluorescent glass, phosphoric acid-based glass, and boric acid-based glass. Alternatively, the substrate 110 may be a quartz substrate or a plastic substrate.

[Organic EL element]
The organic EL element 120 is a light emitting portion of the flat light emitter 100 and is provided above the substrate 110. That is, the organic EL element 120 controls “lighting” and “lighting off” of the flat light emitting body 100 according to the applied voltage.

The organic EL element 120 is provided with the 1st electrode layer 121, the light emission unit 122, and the 2nd electrode layer 123, as shown in FIG. The first electrode layer 121, the light emitting unit 122, and the second electrode layer 123 are sequentially stacked above the substrate 110.

[First electrode layer]
The first electrode layer 121 is an electrode provided on the light emitting surface side, and is provided, for example, on the substrate 110. The first electrode layer 121 is, for example, an anode, and has a potential higher than that of the second electrode layer 123 when the light emitting unit 122 emits light.

The first electrode layer 121 is made of a light-transmitting conductive material. For example, the first electrode layer 121 is made of a transparent conductive material that transmits at least a part of visible light. The first electrode layer 121 is made of, for example, a metal oxide film such as indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), indium gallium zinc oxide (IGZO), etc. Configured For example, the first electrode layer 121 is ITO of 100 nm.

The first electrode layer 121 may be made of a thin metal film (eg, 10 nm) of silver, aluminum, magnesium or the like as a thin film to the extent that light can be transmitted. The first electrode layer 121 may be silver nanowires, carbon nanotubes, or the like. Alternatively, the first electrode layer 121 may be a conductive polymer film such as PEDOT / PSS or polyaniline. The first electrode layer 121 may be a laminated film of the above-described materials.

For example, the first electrode layer 121 is formed by depositing a transparent conductive film on the substrate 110 by a vapor deposition method or a sputtering method, and patterning the deposited transparent conductive film.

The first electrode layer 121 is connected to the first power supply circuit 210 via the terminal portion 121a.

[Light emitting unit]
The light emitting unit 122 is provided between the first electrode layer 121 and the second electrode layer 123, and emits light according to a first voltage applied between the first electrode layer 121 and the second electrode layer 123. Specifically, the light emitting unit 122 is provided on the first electrode layer 121.

The light emitting unit 122 has, for example, a plurality of organic layers. Specifically, the light emitting unit 122 includes a hole injection layer, a hole transport layer, a light emitting layer (organic EL layer), an electron transport layer, and an electron injection layer. An organic layer such as a light emitting layer is made of, for example, an organic material such as diamine, anthracene, or a metal complex. Each layer constituting the light emitting unit 122 is formed by a vapor deposition method, a spin coating method, a cast method or the like.

For example, a first hole transport layer of 60 nm is provided on the first electrode layer 121. On the hole transport layer, a blue fluorescent light emitting layer (including 4,4'-bis (9-ethyl-3-carbazovinylene) -1,1'-biphenyl (BCzVBi) as a blue fluorescent light emitting material, green fluorescent light emitting Layers (including green fluorescent light emitting material (containing triphenylamine (TPA)), first electron transporting layer (4,4'-N, N'-dicarbazolebiphenyl (CBP)) in this order, a film of 35 nm in total It is provided to be thick.

Next, an intermediate layer having a layer structure of Alq 3 (tris (8-quinolinate) aluminum) / Li ₂ O / Alq 3 / HAT-CN 6 (hexaazatriphenylene hexacarbonitrile) is provided. In addition, a 25 nm second hole transport layer is provided.

Furthermore, on the second hole transport layer, a red phosphorescent light emitting layer (containing tris (1-phenylisoquinoline) iridium (III) (Ir (piq) ₃ ) as a red phosphorescent light emitting material), a green phosphorescent light emitting layer (green color Bis (2,2'-benzothienyl) -biridinato-N, C3 iridium (acetylacetonate) (including Bt ₂ Ir (acac)) as a phosphorescent light emitting material, the second electron transport layer in this order, 95 nm in total The film thickness of

[Second electrode layer]
The second electrode layer 123 is an electrode provided on the side opposite to the light emitting surface, and is provided on the light emitting unit 122, for example. The second electrode layer 123 is, for example, a cathode, and has a lower potential than the first electrode layer 121 when the light emitting unit 122 emits light.

The second electrode layer 123 is made of a light-transmitting conductive material. For example, the second electrode layer 123 is made of a transparent conductive material that transmits at least a part of visible light. For example, the second electrode layer 123 is made of the same material as the material that can be used as the first electrode layer 121. For example, the second electrode layer 123 is formed by depositing a transparent conductive film on the light emitting unit 122 by a vapor deposition method or a sputtering method, and patterning the deposited transparent conductive film. For example, the second electrode layer 123 is ITO of 100 nm.

The second electrode layer 123 is connected to the first power supply circuit 210 via the terminal portion 123a.

In addition, as described later, the second electrode layer 123 is one of a pair of electrodes of the electrochromic element 130. Therefore, the second electrode layer 123 is also connected to the second power supply circuit 220 through the terminal portion 131a (that is, the terminal portion 123a).

[Electrochromic device]
The electrochromic element 130 is an example of a light-reflecting variable unit having a pair of electrode layers and having variable light reflectivity and light transparency according to the second voltage applied between the pair of electrode layers. Specifically, the electrochromic element 130 can reversibly change the light reflectivity and the light transmittance according to the second voltage. The electrochromic device 130 controls “transmission” and “reflection” of the flat light emitter 100 according to the applied voltage.

As shown in FIG. 2, the electrochromic element 130 includes a counter electrode layer 131 and a reversible reaction electrode layer 132 which are a pair of electrode layers, and an intermediate layer 133. The counter electrode layer 131, the intermediate layer 133, and the reversible reaction electrode layer 132 are sequentially stacked above the light emitting unit 122.

[Counter electrode layer]
The counter electrode layer 131 is one of a pair of electrode layers of the light reflective variable unit. As shown in FIG. 2, the counter electrode layer 131 is a second electrode layer 123. That is, the counter electrode layer 131 and the second electrode layer 123 are the same conductive film. In other words, the organic EL element 120 and the electrochromic element 130 share the same conductive film as an electrode.

[Reversible Reaction Electrode Layer]
The reversible reaction electrode layer 132 is the other of the pair of electrode layers of the light reflectivity variable unit. The reversible reaction electrode layer 132 is an electrode layer in which light reflectivity and light transparency are reversible according to the second voltage applied between the reversible reaction electrode layer 131 and the counter electrode layer 131. In other words, the reversible reaction electrode layer 132 can switch between the mirror state (reflection state) and the transparent state (transmission state) according to the second voltage.

Specifically, the reversible reaction electrode layer 132 is made of a material capable of changing the light reflectivity and the light transparency by storing or releasing hydrogen and hydrogen ions. For example, the reversible reaction electrode layer 132 is in a transmission state when storing hydrogen (hydrogenation), and is in a reflection state when releasing hydrogen.

For example, the reversible reaction electrode layer 132 is composed of magnesium, an alkaline earth element, a rare earth element, and an alloy containing any of these elements. For example, the reversible reaction electrode layer 132 is made of magnesium-nickel alloy (Mg-Ni), magnesium-titanium alloy (Mg-Ti), magnesium-cobalt alloy (Mg-Co), magnesium-calcium alloy (Mg-Ca), magnesium -With barium alloy (Mg-Ba), magnesium-strontium alloy (Mg-Sr), gadolinium-magnesium alloy (Gd-Mg), samarium-magnesium alloy (Sm-Mg), yttrium-magnesium alloy (Y-Mg), etc. is there.

A transparent conductive film such as ITO may be laminated on the opposite side of the counter electrode layer 131 of the reversible reaction electrode layer 132.

The reversible reaction electrode layer 132 is connected to the second power supply circuit 220 via the terminal portion 132a.

[Intermediate]
The intermediate layer 133 includes a plurality of layers stacked between the counter electrode layer 131 and the reversible reaction electrode layer 132. The thickness of the intermediate layer 133 is determined such that the optical distance between the light emitting unit 122 and the reversible reaction electrode layer 132 is greater than three times the peak wavelength of the light emitted by the light emitting unit 122. The specific configuration will be described later.

[Power supply circuit]
The power supply circuit 200 can independently apply a first voltage supplied to the organic EL element 120 and a second voltage supplied to the electrochromic element 130. As shown in FIG. 2, the power supply circuit 200 includes a first power supply circuit 210 and a second power supply circuit 220.

The first power supply circuit 210 is connected to the first electrode layer 121 and the second electrode layer 123 (that is, the counter electrode layer 131), and a first voltage is applied between the first electrode layer 121 and the second electrode layer 123. Apply. For example, the first power supply circuit 210 is a direct current source or a direct voltage source in which the application direction is fixed and the current value or the voltage value is variable. The first power supply circuit 210 applies a first voltage at which the first electrode layer 121 has a higher potential than the second electrode layer 123 so that a current flows from the first electrode layer 121 to the second electrode layer 123.

The first power supply circuit 210 operates independently of the operation of the second power supply circuit 220. For example, based on an instruction from a user or the like, the first power supply circuit 210 controls the voltage value (the amount of current flowing to the light emitting unit 122) to which the first voltage is applied, not applied, or applied.

For example, when the user instructs "turn off", the first power supply circuit 210 does not apply the first voltage. In addition, when the user instructs “light up”, the first power supply circuit 210 applies the first voltage. In addition, when the user instructs to adjust the brightness, the first power supply circuit 210 controls the voltage value of the first voltage to be applied.

The second power supply circuit 220 is connected to the counter electrode layer 131 (that is, the second electrode layer 123) and the reversible reaction electrode layer 132, and applies a second voltage between the counter electrode layer 131 and the reversible reaction electrode layer 132. Do. For example, the second power supply circuit 220 is a direct current source or a direct current voltage source which has a variable application direction and a fixed current value or voltage value.

When the second power supply circuit 220 applies a second voltage such that the reversible reaction electrode layer 132 has a higher potential than the counter electrode layer 131, the reversible reaction electrode layer 132 is in a reflective state. Conversely, when the second power supply circuit 220 applies the second voltage so that the reversible reaction electrode layer 132 has a lower potential than the counter electrode layer 131, the reversible reaction electrode layer 132 is in the transmission state.

For example, based on an instruction from the user or the like, the second power supply circuit 220 controls the direction in which the second voltage is applied, not applied, or applied. Specifically, when the user instructs switching from “reflection” to “transmission”, for example, when the potential of the counter electrode layer 131 is 0 V, the second power supply circuit 220 By applying the second voltage so that the potential is −5 V, the reversible reaction electrode layer 132 can be brought into the transmission state. Conversely, when the user instructs switching from “transmission” to “reflection”, the second power supply circuit 220 has, for example, the potential of the reversible reaction electrode layer 132 when the potential of the counter electrode layer 131 is 0 V. By applying the second voltage so as to be +5 V, the reversible reaction electrode layer 132 can be in a reflective state.

After the state of the reversible reaction electrode layer 132 is switched by applying the second voltage, the second power supply circuit 220 may stop the application of the second voltage. Even after the application of the second voltage is stopped, the reversible reaction electrode layer 132 maintains the previous state.

[Configuration of terminal section]
Here, the arrangement of the terminal portions connecting the power supply circuit 200 and the flat light emitter 100 will be described with reference to FIGS. 3A and 3B. FIGS. 3A and 3B are a plan view and a partially exploded perspective view showing an arrangement example of the terminal portion of the flat light emitter according to the embodiment of the present invention, respectively.

As shown in FIG. 3A, the three terminal portions 121a, 123a and 132a are arranged in one direction of the flat light emitter 100. For example, since the planar view shape of the flat light emitter 100 according to the present embodiment is rectangular, the three terminal portions 121a, 123a and 132a are arranged side by side on one side of the rectangle.

Although not shown, the flat light emitter 100 has a sealing substrate provided so as to face the substrate 110. The sealing substrate is a light-transmitting substrate, such as a glass substrate. The organic EL element 120 and the electrochromic element 130 are sealed by the substrate 110 and the sealing substrate, and a sealing member such as a resin for bonding the substrate 110 and the sealing substrate. Thereby, the penetration of moisture and the like into the light emitting unit 122 of the organic EL element 120 is suppressed.

The terminal portions 121a, 123a, and 132a are lead electrode portions (electrode pads) drawn to the outside from the sealing space which is a space surrounded by the substrate 110, the sealing substrate, and the sealing member.

The terminal portion 121 a is a lead-out electrode portion for connecting to the first power supply circuit 210. The terminal portion 121 a is electrically connected to the first electrode layer 121. Specifically, as shown in FIG. 3B, the terminal portion 121a is provided so that a part of the first electrode layer 121 extends.

For example, the terminal portion 121 a is formed on the substrate 110 by patterning the conductive film in the same step as the first electrode layer 121. Therefore, the terminal portion 121a is made of, for example, the same material as the first electrode layer 121.

The terminal portion 123 a, that is, the terminal portion 131 a is a lead-out electrode portion for connecting to the first power supply circuit 210 and the second power supply circuit 220. The terminal portion 123a is electrically connected to the second electrode layer 123 (counter electrode layer 131). Specifically, as shown in FIG. 3B, the terminal portion 123a is provided such that a part of the second electrode layer 123 extends.

For example, the terminal portion 123 a is formed on the substrate 110 by patterning the conductive film in the same step as the second electrode layer 123. Therefore, the terminal portion 123a is made of, for example, the same material as the second electrode layer 123.

At this time, the terminal portion 123a is separated from the first electrode layer 121 and the terminal portion 121a. For example, an insulating layer may be provided between the terminal portion 123a and the first electrode layer 121 and the terminal portion 121a.

The terminal portion 132 a is a lead-out electrode portion for connecting to the second power supply circuit 220. The terminal portion 132 a is electrically connected to the reversible reaction electrode layer 132. Specifically, as shown in FIG. 3B, the terminal portion 132a is provided such that a part of the reversible reaction electrode layer 132 extends.

For example, the terminal portion 132 a is formed on the substrate 110 by patterning the conductive film in the same step as the reversible reaction electrode layer 132. Therefore, the terminal portion 132a is made of, for example, the same material as the reversible reaction electrode layer 132.

At this time, the terminal portion 132a is separated from the first electrode layer 121, the terminal portion 121a, the second electrode layer 123, and the terminal portion 123a. For example, an insulating layer may be provided between the terminal portion 132a and the first electrode layer 121, the terminal portion 121a, the second electrode layer 123, and the terminal portion 123a.

The terminal portions 121a, 123a and 132a may be formed in the same process. For example, the terminal portions 121a, 123a, and 132a may be formed in the same process as the first electrode layer 121. That is, the terminal portions 121a, 123a and 132a may be made of the same material (ITO or the like) as the first electrode layer 121.

At this time, the terminal portion 121a is connected to the first electrode layer 121 as shown in FIG. 3B. On the other hand, the terminal portions 123a and 132a are disposed to be separated from the first electrode layer 121 and the terminal portion 121a. Then, the second electrode layer 123 and the reversible reaction electrode layer 132 may be formed so as to be connected to the terminal portions 123a and 132a, respectively.

As described above, by arranging the three terminal portions 121a, 123a, and 132a in one direction of the flat light emitter 100, the flat light emitter 100 can be narrowed.

The terminal portions of the respective layers may be arranged in two directions of the flat light emitter 100 as shown in FIG. 3C. Here, FIG. 3C is a top view which shows another example of arrangement | positioning of the terminal part of the planar light-emitting body 100 which concerns on this Embodiment.

As shown in FIG. 3C, each of the first electrode layer 121, the second electrode layer 123 (counter electrode layer 131), and the reversible reaction electrode layer 132 has two terminal portions 121a, 123a, and 132a. One of the terminal portions 121a, 123a and 132a is provided on one side of the flat light emitter 100, and the remaining terminal portions 121a, 123a and 132a are provided on the other side of the flat light emitter 100.

As shown in FIG. 3C, one side and the other side of the flat light emitting body 100 in which the terminal portion is provided are opposed to each other. That is, in the flat light emitter 100 shown in FIG. 3C, power can be supplied from both sides of each electrode layer. Thereby, the influence of the voltage drop in the electrode layer can be suppressed, and the surface uniformity of light emission and the surface uniformity of control of transmission or reflection can be improved.

Note that one side and the other side of the flat light emitting body 100 in which the terminal portion is provided may be sides adjacent to each other. Even in this case, since power can be supplied from two places of each electrode layer, the influence of voltage drop in the electrode layer can be suppressed, and the surface uniformity of light emission and the surface uniformity of control of transmission or reflection can be improved. It can be done.

Note that three or more terminal portions 121a, 123a and 132a may be provided.

[Intermediate]
Subsequently, a detailed configuration of the intermediate layer 133 provided in the electrochromic element 130 according to the present embodiment will be described with reference to FIG. FIG. 4 is a cross-sectional view showing the configuration of the flat light emitter 100 according to the present embodiment.

The intermediate layer 133 includes, as shown in FIG. 4, an opposing reaction layer 134, a solid electrolyte layer 135, a buffer layer 136, and a catalyst layer 137. Specifically, on the counter electrode layer 131, the counter reaction layer 134, the solid electrolyte layer 135, the buffer layer 136, and the catalyst layer 137 are sequentially stacked.

The opposing reaction layer 134 reacts with the reversible reaction electrode layer 132 via the solid electrolyte layer 135. Specifically, the opposing reaction layer 134 reversibly stores and extracts hydrogen ions necessary for switching between the reflection state and the transmission state of the reversible reaction electrode layer 132. In other words, the opposing reaction layer 134 functions as an ion storage layer.

The opposing reaction layer 134 is made of, for example, a transition metal oxide. Specifically, the opposing reaction layer 134 is made of tungsten oxide (WO ₃ ), iridium oxide (IrO), nickel oxide (NiO), chromium oxide (Cr ₂ O ₃ ), molybdenum oxide (MoO ₃ ), vanadium oxide (V oxide) ) (V ₂ O ₅ ) and the like. The opposing reaction layer 134 is formed, for example, by sputtering.

The solid electrolyte layer 135 is made of a material having the property that hydrogen ions can easily move by application of a voltage. For example, the solid electrolyte layer 135 is a transparent metal oxide thin film provided on the facing reaction layer 134. Note that hydrogen ions can be introduced, for example, by including water remaining in the chamber in a thin film when forming the solid electrolyte layer 135 by sputtering.

The solid electrolyte layer 135 is made of, for example, a metal oxide or a metal sulfide. Specifically, tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (Zr ₂ O ₅ ), silver sulfide (Ag ₂ S), copper sulfide (Cu ₂ S), niobium oxide (Nb ₂ O ₅ ), β-alumina It is composed of a solid electrolyte (β-Al ₂ O ₃ ) or the like.

The buffer layer 136 prevents diffusion of components such as the solid electrolyte layer 135, for example. For example, the buffer layer 136 is a metal thin film provided on the solid electrolyte layer 135. Specifically, the buffer layer 136 is a metal thin film of aluminum, titanium, tantalum or the like. The buffer layer 136 is formed by sputtering, for example.

The catalyst layer 137 supplies hydrogen ions to the reversible reaction electrode layer 132 and obtains hydrogen ions from the reversible reaction electrode layer 132. For example, the catalyst layer 137 is a metal thin film provided on the buffer layer 136 and immediately below the reversible reaction electrode layer 132. Specifically, the catalyst layer 137 is made of palladium, platinum, silver or an alloy of these. The catalyst layer 137 is formed by sputtering, for example.

[Thin layer thickness]
Subsequently, the film thickness of the intermediate layer 133 will be described with reference to FIGS. 5 to 9.

The intermediate layer 133 is configured to have a film thickness determined according to the light emitted by the light emitting unit 122. Specifically, the film thickness of the intermediate layer 133 is such that the optical distance Z between the light emitting unit 122 and the reversible reaction electrode layer 132 is larger than three times the peak wavelength λmax of the light emitted by the light emitting unit 122. It is determined. That is, the intermediate layer 133 is formed to satisfy the condition “Z / λmax> 3” of the optical distance.

In the following, for example, it is assumed that the light emitting unit 122 emits visible light (white light) having a spectrum as shown in FIG. In addition, FIG. 5 is a figure which shows the spectrum of the light which the light emission unit 122 of the planar light-emitting body 100 which concerns on this Embodiment emits. The peak wavelength λmax of visible light shown in FIG. 5 is 620 nm.

Here, in order to investigate the relationship between the film thickness of the intermediate layer 133 and the angle dependency of the flat light emitter 100, first, simulation was performed on the flat light emitter having three different film thicknesses. Specifically, simulations were performed in each of the “reflection lighting mode” and the “transmission lighting mode”.

Note that the angle dependency is a characteristic of the chromaticity change of the luminescent color (color of light emitted by the light emitting unit 122) with respect to the angle at which the flat light emitting body 100 is viewed. When the chromaticity change with respect to angle is small, the angular dependence is small, and when the chromaticity change with angle is large, the angular dependence is large.

In other words, when the angle dependency is large, the emission color changes significantly when the viewing angle is changed. On the contrary, when the angle dependency is small, even if the viewing angle is changed, the luminescent color does not change much. Therefore, it is preferable that the angle dependency be small.

FIG. 6 is a view showing an example of the material and film thickness of each layer of the variable light reflective unit 130 of the flat light emitter 100 according to the present embodiment.

In FIG. 6, Z of “Z / λmax” is an optical distance between the light emitting unit 122 and the reversible reaction electrode layer 132. Specifically, it is the product sum of the refractive index n and the film thickness d of each of a plurality of layers provided between the light emitting unit 122 and the reversible reaction electrode layer 132. That is, Z is expressed by the following (Expression 1).

(Expression 1) Z = Zn _i d _i

Here, n _i indicates the refractive index of the ith layer, and d _i indicates the film thickness of the ith layer.

As shown in FIG. 4, a second electrode layer 123 (counter electrode layer 131) and an intermediate layer 133 are provided between the light emitting unit 122 and the reversible reaction electrode layer 132. Specifically, the second electrode layer 123, the opposite reaction layer 134, the solid electrolyte layer 135, the buffer layer 136, and the catalyst layer 137 are stacked in this order between the light emitting unit 122 and the reversible reaction electrode layer 132. There is.

Therefore, the optical distance Z is the product (optical film thickness) of the refractive index n and the film thickness d of each of the second electrode layer 123, the facing reaction layer 134, the solid electrolyte layer 135, the buffer layer 136, and the catalyst layer 137. It becomes a sum. In the case of a material such as metal having an extinction coefficient k larger than the refractive index n, it is not necessary to use for calculation of the optical distance. Specifically, as shown in FIG. 6, the buffer layer 136 and the catalyst layer 137 have a size of about several nm, and are sufficiently smaller than the other layers. You do not have to put in

Since the peak wavelength λmax is 620 nm, “Z / λmax” of the three types of flat light emitters of (a) to (c) shown in FIG. 37, about 3.01, about 3.66.

The optical constants (refractive index n and extinction coefficient k) shown in FIG. 6 indicate values of an example used in the simulation. As for the optical constant of Mg—Ni, the value of Mg is used during reflection, and the value of MgH ₂ is used during transmission.

FIGS. 7A and 7B are diagrams showing the relationship between the optical distance of the variable light reflective unit 130 of the flat light emitter 100 according to the present embodiment and the angular dependence of the emission color in the reflection state and the transmission state, respectively. is there. Specifically, FIGS. 7A and 7B show the simulation results of the angular dependency of each of the three types of flat light emitters of (a) to (c) shown in FIG. It is shown as a 'v' chromaticity diagram.

7A and 7B, the black plots indicate the case of “0 °”, and the white plots of the larger plots indicate the case of “80 °”. “0 °” or “80 °” indicates an angle based on a direction perpendicular to the light emitting surface of the flat light emitter 100 (ie, the stacking direction). Specifically, “0 °” indicates a case where the light emitting surface is viewed from the front of the flat light emitting body 100. The angle increases in steps of 10 ° from the filled plot towards the filled plot.

In the chromaticity space shown in FIGS. 7A and 7B, the maximum value of the distance between any two points is shown as Δu′v ′ in FIG. That is, the larger the difference Δu'v ', the larger the difference in chromaticity due to the difference in angles, that is, the stronger the angle dependency. Therefore, as shown in FIG. 6, it can be seen that as the planar light emitter with the larger “Z / λmax”, Δu′v ′ becomes smaller and the change in chromaticity due to the angle is suppressed.

Therefore, the film thickness of the intermediate layer 133 is determined such that the optical distance Z is increased. Thus, in order to improve the angular dependency, that is, to reduce the angular dependency, the film thickness of the intermediate layer 133 may be determined so as to increase the optical distance Z.

For example, in the intermediate layer 133, each layer of the intermediate layer 133 such that the film thickness of the facing reaction layer 134 or the solid electrolyte layer 135 is the largest among the plurality of layers constituting the intermediate layer 133 and the second electrode layer 123. Film thickness is determined. In other words, by adjusting the film thickness of the opposing reaction layer 134 or the solid electrolyte layer 135, the intermediate layer 133 satisfying the above-described optical distance condition (Z / λmax> 3) is formed.

There is a limitation that the film thickness can not be increased for other layers. For example, the buffer layer 136 and the catalyst layer 137 are made of metal. Therefore, when the film thickness of the buffer layer 136 and the catalyst layer 137 is increased, it is difficult to transmit the light from the light emitting unit 122.

The second electrode layer 123 is formed of a transparent conductive film such as ITO that absorbs part of light in the visible light band. For this reason, when the film thickness of the second electrode layer 123 is increased, part of the light from the light emitting unit 122 is absorbed, and the emission color is colored.

Therefore, by adjusting the film thickness of the opposing reaction layer 134 or the solid electrolyte layer 135, the intermediate layer 133 satisfying the above-described optical distance condition (Z / λmax> 3) is formed.

From the above, in order to improve the angular dependency, the film thickness of the intermediate layer 133 may be increased as a simple configuration. However, when the film thickness of the intermediate layer 133 is too large, the operation of the electrochromic element 130 is affected, or the light extraction efficiency from the light emitting unit 122 is deteriorated. Further, even if the film thickness of the intermediate layer 133 is increased more than necessary, no change in the angle dependency is observed.

Therefore, the film thickness of the intermediate layer 133 is determined so that, for example, the optical distance Z between the light emitting unit 122 and the reversible reaction electrode layer 132 is 6 times or less of the peak wavelength λmax of light emitted by the light emitting unit 122 Preferably. That is, the intermediate layer 133 is preferably formed to satisfy “Z / λmax ≦ 6”.

[Summary]
As described above, the flat light emitting body 100 according to the present embodiment includes the light transmitting substrate 110 and the light transmitting first electrode layer 121 and the second electrode sequentially stacked above the substrate 110. A pair of light emitting units 122 provided between the layer 123 and the first electrode layer 121 and the second electrode layer 123 and emitting light according to the first voltage applied between the first electrode layer 121 and the second electrode layer 123; Electrochromic device having the opposite electrode layer 131 and the reversible reaction electrode layer 132, and the light reflectivity and the light transmittance being variable according to the second voltage applied between the opposite electrode layer 131 and the reversible reaction electrode layer 132 And the counter electrode layer 131 is the second electrode layer 123.

Moreover, the illuminating device 10 which concerns on this Embodiment is provided with the planar light-emitting body 100 and the power supply circuit 200 which can apply a 1st voltage and a 2nd voltage independently.

As described above, in the planar light emitter 100 according to the present embodiment and the lighting apparatus 10 including the planar light emitter 100, the organic EL element 120 and the electrochromic element 130 are integrated. Specifically, the second electrode layer 123 which is the cathode of the organic EL element 120 and the counter electrode layer 131 of the electrochromic element 130 are common, that is, constitute the same layer.

Therefore, by using the second electrode layer 123 and the counter electrode layer 131 in common, the number of layers through which light from the light emitting unit 122 passes is reduced. Therefore, the loss of light extraction from the light emitting unit 122 due to the difference in refractive index between layers is smaller than when the organic EL element 120 and the electrochromic element 130 are separately stacked, and the light emission efficiency can be increased. Thereby, according to the planar light-emitting body 100 and the illuminating device 10 which concern on this Embodiment, a reflectance and the transmittance | permeability can be adjusted and luminous efficiency can be made high.

Further, since the organic EL element 120 and the electrochromic element 130 are integrated, the planar light emitter 100 can be thinner than in the case where the organic EL element 120 and the electrochromic element 130 are separately laminated. . Therefore, the flat light emitter 100 can be easily bent, and can be used as the flexible lighting device 10.

In addition, by using the second electrode layer 123 and the counter electrode layer 131 in common, the number of components (specifically, the number of electrode layers) and the number of manufacturing steps can be reduced, thereby reducing the cost. can do.

Also, for example, the reversible reaction electrode layer 132 has variable light reflectivity and light transparency according to the second voltage, and the optical distance between the light emitting unit 122 and the reversible reaction electrode layer 132 is the light emitting unit 122. Greater than three times the peak wavelength of the light emitted by

Generally, in order to reduce the angle dependency, a diffusion film for diffusing light can be used. However, as in the flat light emitting body 100 according to the present embodiment, when it is required that the opposite side can be seen through the flat light emitting body 100 (window use etc.), the diffusion film can not be used.

Therefore, according to the flat light emitting body 100 according to the present embodiment, by making the optical distance between the light emitting unit 122 and the reversible reaction electrode layer 132 appropriate, the angle of the light emission color can be obtained without using the diffusion film. The dependency can be reduced.

In addition, for example, the electrochromic element 130 includes the intermediate layer 133 including a plurality of stacked layers between the counter electrode layer 131 and the reversible reaction electrode layer 132, and the intermediate layer 133 includes the solid electrolyte layer 135 and a solid. The film thickness of the solid electrolyte layer 135 or the counter reaction layer 134 includes the counter reaction layer 134 that reacts with the reversible reaction electrode layer 132 via the electrolyte layer 135, and the film thickness of the solid electrolyte layer 135 or the counter reaction layer 134 is at maximum among the intermediate layer 133 and the second electrode layer 123. is there.

As a result, it is possible to reduce the angle dependency while suppressing the influence on the light extraction efficiency and the change of the light emission color.

(Modification 1)
Below, the modification 1 of the flat light-emitting body which concerns on this Embodiment is demonstrated using FIG. FIG. 8 is a cross-sectional view showing the configuration of a flat light emitter 300 according to the present modification.

The flat light emitter 300 shown in FIG. 8 is different from the flat light emitter 100 shown in FIG. 4 in that an electrochromic element 330 is provided instead of the electrochromic element 130. The following description will focus on the differences.

Specifically, the electrochromic element 330 includes an intermediate layer 333 instead of the intermediate layer 133. The intermediate layer 333 comprises a solid electrolyte layer 335 instead of the solid electrolyte layer 135.

In the solid electrolyte layer 335, asperities with a period of 0.1 μm to 10 μm are formed in the horizontal direction of the substrate. Specifically, on the upper surface of the solid electrolyte layer 335, concave portions 335a and convex portions 335b are repeatedly formed in a matrix at a cycle of 0.1 μm to 10 μm. The period corresponds to the total width of the concave portion 335a and the convex portion 335b.

The shape of the recess 335 a and the protrusion 335 b may be any shape. For example, the plan view shape of the recess 335 a and the protrusion 335 b is a rectangle, a circle, an ellipse, or the like. For example, as shown in FIG. 8, the cross-sectional shapes of the concave portion 335 a and the convex portion 335 b have a taper. That is, the concave portion 335a and the convex portion 335b have a surface inclined with respect to the stacking direction. The concave portion 335a and the convex portion 335b may have a plane parallel to the stacking direction.

The concave portion 335 a and the convex portion 335 b are formed by removing a part by etching or the like after film formation. That is, the removed portion is the concave portion 335a, and the remaining portion is the convex portion 335b.

Specifically, first, a metal oxide film (for example, tantalum oxide) to be a material of the solid electrolyte layer 335 is formed on the facing reaction layer 134 by sputtering or the like. Next, part of the metal oxide film is removed by dry etching (for example, RIE (Reactive Ion Etching)) or the like using a mask having an opening at a position corresponding to the concave portion 335a. Thereby, the solid electrolyte layer 335 in which the recess 335 a and the protrusion 335 b are formed is formed. The height of the unevenness is, for example, several nm to several tens of nm.

The buffer layer 136 and the catalyst layer 137 are stacked on the unevenness. For this reason, as shown in FIG. 8, the buffer layer 136 and the catalyst layer 137 become layers along the concavo-convex shape. Simply put, the buffer layer 136 and the catalyst layer 137 have a corrugated shape.

Although the example shown in FIG. 8 shows an example in which the solid electrolyte layer 335 is formed with asperities, it is not limited thereto. For example, asperities may be formed on the opposing reaction layer 134.

As described above, in the flat light emitting body 300 according to the present modification, the electrochromic element 330 has the intermediate layer 333 including a plurality of stacked layers between the counter electrode layer 131 and the reversible reaction electrode layer 132, The intermediate layer 333 includes a solid electrolyte layer 335 and a facing reaction layer 134 that reacts with the reversible reaction electrode layer 132 via the solid electrolyte layer 335, and at least one of the solid electrolyte layer 335 and the facing reaction layer 134 is a substrate. Irregularities having a period of 0.1 μm to 10 μm are formed in the horizontal direction.

Thereby, since the reflected light by the reversible reaction electrode layer 132 can be diffused by the unevenness, the angle dependency can be reduced without increasing the film thickness. In addition, since the unevenness diffuses the reflected light, in the case of the reflection mode, it is not specular reflection but diffuse reflection.

(Modification 2)
Below, the modification 2 of the flat light-emitting body which concerns on this Embodiment is demonstrated using FIG. FIG. 9 is a cross-sectional view showing a part of the configuration of a flat light emitter 400 according to this modification.

The flat light emitter 400 shown in FIG. 9 is different from the flat light emitter 100 shown in FIG. 4 in that an organic EL element 420 and an electrochromic element 430 are provided instead of the organic EL element 120 and the electrochromic element 130. ing. The following description will focus on the differences.

The organic EL element 420 includes a light emitting unit 422 and a second electrode layer 423 instead of the light emitting unit 122 and the second electrode layer 123. In addition, the electrochromic element 430 includes a counter electrode layer 431, a reversible reaction electrode layer 432, and an intermediate layer 433. The light emitting unit 422, the second electrode layer 423 (counter electrode layer 431), the reversible reaction electrode layer 432, and the intermediate layer 433 have the materials except for the shapes, respectively, such as the light emitting unit 122 and the second electrode layer 123 (counter electrode layer 131). And the reversible reaction electrode layer 132 and the intermediate layer 133 are the same.

In the flat light emitter 400 according to the present modification, as shown in FIG. 9, the electrochromic element 430 covers the light emitting unit 422. That is, the electrochromic element 430 extends outward from the outer edge of the light emitting unit 422 in plan view. Specifically, the counter electrode layer 431 (second electrode layer 423), the intermediate layer 433 and the reversible reaction electrode layer 432 extend outward from the outer edge of the light emitting unit 422 in plan view. For example, the respective edges of the counter electrode layer 431 (second electrode layer 423), the intermediate layer 433 and the reversible reaction electrode layer 432 are in contact with the substrate 110 as shown in FIG.

Accordingly, when the reversible reaction electrode layer 432 is in the reflection state, the light from the light emitting unit 422 can be emitted to the light emitting surface side with almost no leak. Thus, the light leakage of the light from the light emitting unit 422 can be suppressed to further enhance the light emission efficiency.

As described above, in the flat light emitter 400 according to the present modification, the electrochromic element 430 extends outward from the outer edge of the light emitting unit 422 in plan view.

Thereby, when the electrochromic element 430 is in the reflection state, the light from the light emitting unit 422 can be reflected and emitted to the light emitting surface side. Thus, the light leakage of the light from the light emitting unit 422 can be suppressed to further enhance the light emission efficiency.

In the flat light emitter 400 according to the present modification, all layers included in the electrochromic element 430 extend outward from the outer edge of the light emitting unit 422 in plan view. That is, as shown in FIG. 9, the upper layer side covers the lower layer side. That is, in plan view, the layer on the upper side extends outward from the outer edge of the layer on the lower side.

At this time, at least the reversible reaction electrode layer 432 may extend outward from the outer edge of the light emitting unit 422 in order to suppress light leakage.

(Others)
As mentioned above, although the planar light-emitting body and illuminating device which concern on this invention were demonstrated based on the said embodiment and its modification, this invention is not limited to said embodiment.

For example, the flat light emitter according to the above-described embodiment and the modification may further have a stress relaxation structure. That is, in order to make the flat light emitter easier to bend, the flat light emitter may have a stress relaxation structure.

The stress relaxation structure is, for example, a plurality of through holes penetrating the flat light emitter in the stacking direction, or a plurality of grooves provided on a flat light emitter substrate or the like. The stress caused when the flat light emitter is bent can be relaxed by the plurality of through holes or grooves, and the flat light emitter can be easily bent without being broken.

Further, for example, although the example in which the periodic unevenness is formed in the solid electrolyte layer 335 or the facing reaction layer 134 in the first modification example is described, the present invention is not limited thereto. The unevenness may not be periodically formed, and for example, the concave portion 335a and the convex portion 335b may be randomly arranged. Further, the light scattering structure may be provided to the intermediate layer 333 as well as the unevenness.

Further, for example, although the example in which the first electrode layer 121 is provided on the substrate 110 is described in the above embodiment and the modification, the present invention is not limited thereto. For example, the first electrode layer 121 may be provided on the planarization film provided on the substrate 110.

Further, for example, although the example in which the first electrode layer 121 is an anode and the second electrode layer 123 is a cathode is shown in the above-described embodiment and modification, the opposite may be applied. That is, the first electrode layer 121 may be a cathode and the second electrode layer 123 may be an anode.

Further, for example, although the electrochromic element is shown as the light reflectivity variable unit in the above embodiment and the modification, the present invention is not limited to this. A light control mirror device such as a gas chromic device or a cholesteric liquid crystal can be used.

Further, for example, in the above-described embodiment and the modification, an example in which the plan view shape of the flat light emitter is rectangular is described, but the present invention is not limited thereto. The plan view shape of the planar light emitter may be a closed shape drawn as a straight line or a curve, such as a polygon, a circle or an ellipse.

In addition, the present invention can be realized by arbitrarily combining components and functions in each embodiment without departing from the scope of the present invention or embodiments obtained by applying various modifications that those skilled in the art may think to each embodiment. The form is also included in the present invention.

10 Lighting device 100, 300, 400 Planar light emitter 110 Substrate 120, 420 Organic EL element 121 First electrode layer 122, 422 Light emitting unit 123, 423 Second electrode layer 130, 330, 430 Electrochromic element (light reflective variable unit )
131, 431 Counter electrode layer 132, 432 Reversible reaction electrode layer 133, 333, 433 Intermediate layer 134 Counter reaction layer 135, 335 Solid electrolyte layer 200 Power circuit 335a Concave portion 335b Convex portion

Claims (6)

1. A translucent substrate,
   A light transmitting first electrode layer and a second electrode layer sequentially stacked above the substrate;
   A light emitting unit provided between the first electrode layer and the second electrode layer and emitting light according to a first voltage applied between the first electrode layer and the second electrode layer;
   A light reflective variable unit having a pair of electrode layers, the light reflectivity and the light transparency being variable according to a second voltage applied between the pair of electrode layers,
   One of the pair of electrode layers is the second electrode layer.
2. The other of the pair of electrode layers is a reversible reaction electrode layer in which light reflectivity and light transparency are variable according to the second voltage,
   The flat light-emitting body according to claim 1, wherein an optical distance between the light emitting unit and the reversible reaction electrode layer is larger than three times a peak wavelength of light emitted by the light emitting unit.
3. The light reflective variable unit has a plurality of layers stacked between the pair of electrode layers,
   The plurality of layers are
   A solid electrolyte layer,
   An opposing reaction layer that reacts with the other of the pair of electrode layers via the solid electrolyte layer,
   The flat light-emitting body according to claim 1 or 2, wherein the film thickness of the solid electrolyte layer or the facing reaction layer is the largest among the plurality of layers and the second electrode layer.
4. The light reflective variable unit has a plurality of layers stacked between the pair of electrode layers,
   The plurality of layers are
   A solid electrolyte layer,
   An opposing reaction layer that reacts with the other of the pair of electrode layers via the solid electrolyte layer,
   The flat light-emitting body according to claim 1 or 2, wherein an unevenness having a period of 0.1 μm to 10 μm is formed in at least one of the solid electrolyte layer and the facing reaction layer in the substrate horizontal direction.
5. The flat light-emitting body according to any one of claims 1 to 4, wherein the variable light-reflecting unit extends outward from an outer edge of the light-emitting unit in plan view.
6. A flat light emitter according to any one of claims 1 to 5;
   A power supply circuit capable of independently applying the first voltage and the second voltage.

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