# Patent

## Title
Sealed structure, light-emitting device, electronic device, and lighting device

## Abstract

A sealed structure with high sealing capability, in which a pair of substrates is attached to each other with a glass layer is provided. The sealed structure has a first and second substrates, a first surface of the first substrate facing a first surface of the second substrate, and the glass layer which is in contact with the first and second substrates, defines a space between the first and second substrates, and is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. In at least one of respective welded regions between the glass layer and the first or second substrate, the width of the corner portion is larger than that of the side portion.

## Background
This application is a continuation of copending U.S. application Ser. No. 13/686,335, filed on Nov. 27, 2012 which is incorporated herein by reference.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sealed structure using a pair of substrates and a glass layer. Further, the present invention relates to a light-emitting device, an electronic device, and a lighting device each using organic electroluminescence (hereinafter also referred to as EL).
2. Description of the Related Art
In recent years, development of light-emitting devices and display devices has been actively promoted, and improvements in reliability and yield, and the like have been demanded.
A sealed structure with high sealing capability can be used suitably for a display device or a light-emitting device in which a display element, a light-emitting element, or the like is an object to be sealed.
For example, in a light-emitting device, an element whose properties such as reliability are rapidly deteriorated by exposure to the air containing moisture or oxygen, such as a light-emitting element using organic electroluminescence (also referred to as an organic EL element), is preferably provided inside a sealed structure with high sealing capability.
Patent Document 1 discloses an organic EL panel in which a substrate and a sealing substrate are attached to each other with an adhesive layer.
REFERENCE
Patent Document 1: Japanese Published Patent Application No. 2011-81944
SUMMARY OF THE INVENTION
Further, in fabricating or using a light-emitting device, force is likely to be more applied to a corner portion of the light-emitting device, and thus a pair of attached substrates of the light-emitting device tends to be detached from each other from the corner portion.
For example, a technique in which a plurality of light-emitting devices (or display devices) is formed in one substrate, a trench is formed (scribed) in a top surface of the one substrate and a top surface of the other substrate, and the substrates are cut along the trench is known. In cutting the substrates in the technique, force tends to be concentrated on a corner portion of the light-emitting device, so that the pair of attached substrates tends to be detached from each other.
Therefore, it is requested that the adhesion between a substrate and an adhesive layer be as high as possible at a corner portion of a sealed structure.
As an example of an adhesive for attaching the pair of substrates, resin such as a light curing resin or a heat curing resin is known. Upon attachment of the pair of substrates, the shape of the resin sandwiched by the pair of substrates is changed to, for example, increase its width by crush. That is, the shape of the resin provided over one of the substrates is different between before and after the attachment.
For example, in the case where the application quantity of the resin is large, the resin may spread out of its predetermined region on attachment to be mixed into a region where an object to be sealed is provided, whereby the object is contaminated. To the contrary, too much reduction in application quantity of the resin in order to suppress the spread out of its appropriate region may lead to a lack of sufficient resin in the predetermined region after the attachment (the object cannot be sealed enough in some cases).
One object of one embodiment of the present invention is to provide a sealed structure with high sealing capability.
Further, one object of one embodiment of the present invention is to provide a highly reliable light-emitting device in which an organic EL element is sealed by the sealed structure.
Still further, one object of one embodiment of the present invention is to provide a highly reliable electronic device or a highly reliable lighting device using the light-emitting device.
A sealed structure of one embodiment of the present invention has a space surrounded by a pair of substrates and a glass layer, in which at least one of the substrate has a corner portion, the glass layer is provided along the periphery of the one substrate having a corner portion, and in at least one of a region where the glass layer is attached to the one substrate and a region where the glass layer is attached to the other substrate (the region also referred to as a welded region between the glass layer and the substrate), the width of its corner portion is larger than that of its side portion. Accordingly, the area of at least the one welded region between the glass layer and the one substrate is large in a corner portion of the sealed structure, so that the adhesion between the glass layer and the substrate in the corner portion can be increased. Consequently, if force is concentrated on the corner portion of the sealed structure, detachment of the pair of attached substrates from each other can be suppressed.
In this specification, the interval between an inner contour and an outer contour of the welded region between the glass layer and the substrate is referred to as the width of the welded region. In this specification, for example, the interval between the inner contour and the outer contour in the corner portion (side portion) of the welded region is referred to as the width of the corner portion (side portion). Likewise, the interval between an inner contour and an outer contour of the glass layer is referred to as the width of the glass layer.
In the above-described embodiment of the present invention, the glass layer is used to attach the pair of substrates. The sealing capability of glass is higher than that of resin, and thus glass is preferable. In addition, glass is less likely to be deformed on attachment, and thus the shape of the glass layer after attachment can be predicted before the attachment, which enables suppression of generation of such a defect that the glass layer does not exist in its predetermined region after the attachment and thus an object to be sealed cannot be sealed enough. Accordingly, a sealed structure with high sealing capability can be manufactured at high yield. Further, the glass layer (or glass frit, frit paste, or the like for forming the glass layer) can be provided over the substrate, in its desired shape after attachment, which leads to simplification of manufacturing of the sealed structure.
Specifically, one embodiment of the present invention is a sealed structure including a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate, and a glass layer which is in contact with the first substrate and the second substrate, defines a space between the first substrate and the second substrate, and is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. In at least one of a welded region between the glass layer and the first substrate and a welded region between the glass layer and the second substrate, the width of the corner portion is larger than that of the side portion.
The sealing capability of the sealed structure is high because the pair of substrates is attached with the glass layer. In addition, in the sealed structure, detachment of the pair of substrates attached with the glass layer from each other can be suppressed even if force is concentrated on the corner portion because in the corner portion, the area of the welded region between the glass layer and the substrate is large and the adhesion between the glass layer and the substrate is high. Further, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion in the manufacturing process of the sealed structure, which leads to an improvement in yield.
Note that the present invention encompasses not only a structure in which the substrate is in direct contact with the glass layer, but also a structure in which the substrate is in indirect contact with the glass layer through a film provided over the substrate. In this specification, the welded region between the glass layer and the substrate may denote a welded region between the glass layer and the film provided over the substrate, depending on the structure.
According to one embodiment of the present invention, even in the case where the substrate is in indirect contact with the glass layer through the film provided over the substrate, the area of a welded region between the film and the glass layer in a corner portion of the sealed structure is large, whereby the adhesion between the film and the glass layer in the corner portion can be improved. Accordingly, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the sealed structure.
One embodiment of the present invention is a sealed structure including a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate, and a glass layer which is in contact with the first substrate and the second substrate, defines a space between the first substrate and the second substrate, and is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. In at least one of a welded region between the glass layer and the first substrate and a welded region between the glass layer and the second substrate, the radius of the outer contour is smaller than or equal to that of the inner contour in its corner portion.
In the sealed structure, in at least one of the welded region between the glass layer and the first substrate and the welded region between the glass layer and the second substrate, the corner portion of the outer contour and the corner portion of the inner contour each individually have a shape along a circle. In this specification, the radius of a circle along which the corner portion of the contour has the shape is referred to as the radius of the contour.
With the structure in which the radius of the outer contour is smaller than or equal to that of the inner contour, the adhesion between the glass layer and the substrate in the corner portion of the sealed structure can be improved because the area of the welded region between the glass layer and the substrate is large in the corner portion.
One embodiment of the present invention is a light-emitting device including a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate, and a glass layer which is in contact with the first substrate and the second substrate, defines a region for an object to be sealed between the first substrate and the second substrate, and is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. The region for an object to be sealed includes a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes. In at least one of a welded region between the glass layer and the first substrate and a welded region between the glass layer and the second substrate, the width of the corner portion is larger than that of the side portion.
In the above-described light-emitting device, the glass layer, which has a high effect of sealing, is used as a sealant. Accordingly, deterioration of the light-emitting element (organic EL element) attributable to entry of an impurity such as moisture or oxygen from the outside of the light-emitting device can be suppressed.
Further, since in at least one of the welded region between the glass layer and the first substrate and the welded region between the glass layer and the second substrate in the above-described light-emitting device, the width of the corner portion is larger than that of the side portion, the area of the welded region between the glass layer and the substrate in a corner portion of the light-emitting device is large, whereby the adhesion between the glass layer and the substrate in the corner portion can be improved. Accordingly, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the light-emitting device. Further, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion in the manufacturing process of the light-emitting device, which leads to an improvement in yield.
One embodiment of the present invention is a light-emitting device including a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate, and a glass layer which is in contact with the first substrate and the second substrate, defines a region for an object to be sealed between the first substrate and the second substrate, and is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. The region for an object to be sealed includes a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes. In at least one of a welded region between the glass layer and the first substrate and a welded region between the glass layer and the second substrate, the radius of the outer contour is smaller than or equal to that of the inner contour in its corner portion.
In the light-emitting device, in at least one of the welded region between the glass layer and the first substrate and the welded region between the glass layer and the second substrate, the corner portion of the outer contour and the corner portion of the inner contour each individually have a shape along a circle. With the structure in which the radius of the outer contour is smaller than or equal to that of the inner contour, the adhesion between the glass layer and the substrate in the corner portion of the light-emitting device can be improved because the area of the welded region between the glass layer and the substrate is large in the corner portion.
One embodiment of the present invention is an electronic device using the light-emitting device. One embodiment of the present invention is a lighting device using the light-emitting device. Application of the light-emitting device whose pair of substrates attached is less likely to be detached from each other even if force is concentrated on its corner portion owing to its high adhesion between the substrate and the glass layer in the corner portion enables a highly reliable electronic device or a highly reliable lighting device to be achieved.
According to one embodiment of the present invention, a sealed structure with high sealing capability can be provided.
Further, a highly reliable light-emitting device in which an organic EL element is sealed by the sealed structure can be provided.
Still further, a highly reliable electronic device or a highly reliable lighting device using the light-emitting device can be provided.



BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIGS. 1A1 to 1A3 and FIGS. 1B1 to 1B3 illustrate a sealed structure of one embodiment of the present invention and a sealed structure of a comparison example, respectively;
FIGS. 2A to 2E illustrate sealed structures of embodiments of the present invention;
FIGS. 3A and 3B illustrate a light-emitting device of one embodiment of the present invention;
FIGS. 4A and 4B illustrate a light-emitting device of one embodiment of the present invention;
FIGS. 5A and 5B illustrate a light-emitting device of one embodiment of the present invention;
FIGS. 6A to 6C illustrate EL layers;
FIGS. 7A to 7E illustrate electronic devices and a lighting device of embodiments of the present invention;
FIG. 8 illustrates lighting devices of embodiments of the present invention;
FIGS. 9A to 9C illustrate an electronic device of one embodiment of the present invention;
FIGS. 10A to 10C illustrate a method for manufacturing a sealed structure of one embodiment of the present invention in Example 1;
FIGS. 11A and 11B show results of Example 1; and
FIGS. 12A and 12B show results of Example 1.



DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention are described in detail using the drawings. The present invention is not limited to the following description, and it will be easily understood by those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description in the following embodiments. In the structures of the present invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in the drawings, and description of the portions is not repeated.
Embodiment 1
In this embodiment, a sealed structure of one embodiment of the present invention is described using FIGS. 1A1 to 1A3, FIGS. 1B1 to 1B3, and FIGS. 2A to 2E.
A sealed structure of one embodiment of the present invention includes a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate, and a glass layer which is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. The first substrate is attached to the second substrate with the glass layer. In at least one of a welded region between the glass layer and the first substrate and a welded region between the glass layer and the second substrate, the width of the corner portion is larger than that of the side portion.
The sealing capability of the sealed structure is high because the pair of substrates is attached with the glass layer. In addition, the adhesion between the glass layer and the substrate is high in the corner portion because the area of the welded region between the glass layer and the substrate is large in the corner portion. Thus, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the sealed structure. Further, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion in the manufacturing process of the sealed structure, which leads to an improvement in yield.
In the case where resin is used to attach a pair of substrates, the shape of the resin sandwiched by the pair of substrates is changed to, for example, increase the width by crush.
For example, in the case where the application quantity of the resin is large, the resin may spread out of its predetermined region on attachment to be mixed into a region where an object to be sealed, whereby the structure is contaminated. To the contrary, too much reduction in application quantity of the resin in order to suppress the spread out of its appropriate region may lead to a lack of sufficient resin in the predetermined region after the attachment (the structure cannot be sealed enough in some cases).
In the above-described embodiment of the present invention, the glass layer is used to attach the pair of substrates. The sealing capability of glass is higher than that of resin, and thus glass is preferable. In addition, glass is less likely to be deformed on attachment, and thus the shape of the glass layer after attachment can be predicted before the attachment, which enables suppression of generation of such a defect that the glass layer does not exist in its predetermined region after the attachment and thus an object to be sealed cannot be sealed enough. Accordingly, a sealed structure with high sealing capability can be manufactured at high yield. Further, the glass layer (or glass frit, frit paste, or the like for forming the glass layer) can be provided over the substrate, in its desired shape after attachment, which leads to simplification of manufacturing of the sealed structure.
In this embodiment, for ease of description, it is supposed that the shape of the glass layer in its formed state over the one substrate is the same as that of the welded region between the glass layer and the substrate (and/or the counter substrate) in the state after attachment.
A plan view of a sealed structure of one embodiment of the present invention is shown in FIG. 1A1. An enlarged view of a region surrounded by a dotted line 111 in FIG. 1A1 is shown in FIGS. 1A2 and 1A3.
In the sealed structure of the embodiment of the present invention shown in FIGS. 1A1 to 1A3, a glass layer 105a is provided over a quadrangular substrate 101 along the periphery of the substrate 101. Then, the substrate 101 is attached to a counter substrate with the glass layer 105a, so that a space 102 surrounded by the pair of substrates and the glass layer 105a is provided.
In this embodiment, a surface of the substrate and a surface of the counter substrate, which face each other, have the same area. For example, in the plan view of the sealed structure shown in FIG. 1A1, the shape of the counter substrate is the same as that of the substrate 101.
An object to be sealed is included in the space 102. There is no particular limitation on the object to be sealed; for example, an organic EL element, an element included in a plasma display, a liquid crystal element, and the like can be given. A transistor or a color filter may also be provided.
A plan view of a sealed structure of a comparative example is shown in FIG. 1B1. An enlarged view of a region surrounded by a dotted line 112 in FIG. 1B1 is shown in FIGS. 1B2 and 1B3.
In the sealed structure of the comparative example shown in FIGS. 1B1 to 1B3, a glass layer 105b is provided over a quadrangular substrate 101 along the periphery of the substrate 101. Then, the substrate 101 is attached to a counter substrate with the glass layer 105b, so that a space 102 surrounded by the pair of substrates and the glass layer 105b is provided.
A difference between the glass layer 105a of the sealed structure of one embodiment of the present invention and the glass layer 105b of the sealed structure of the comparative example (which can also be conceived as a difference between a welded region between the glass layer 105a and the substrate 101 and a welded region between the glass layer 105b and the substrate 101) is described below.
As shown in FIG. 1A2, as for the glass layer 105a, a width of the corner portion, W1 is larger than that of the side portion, W2.
On the other hand, as shown in FIG. 1B2, as for the glass layer 105b, a width of the side portion, W4 is equal to that of the corner portion, W3.
In this specification, the width of the side portion refers to the width of a line which is perpendicular to the side. Further, the width of the corner portion refers to the width of a line which connects an intersection in respective extensions of two sides of the outer contour, which do not face each other (see an intersection 15 in FIG. 1A2) to the inner contour by the most direct way.
It can be seen from FIGS. 1A2 and 1B2 that the area of the welded region between the glass layer and the substrate in a corner portion of the sealed structure is larger in the sealed structure of the embodiment of the present invention in which the width of the corner portion is larger than that of the side portion in a corner portion of the welded region, than in the sealed structure of the comparison example. Therefore, application of one embodiment of the present invention enables the adhesion between the glass layer and the substrate in the corner portion of the sealed structure to be improved.
Further, as shown in FIG. 1A3, in a corner portion of the glass layer 105a, a radius of the outer contour, R1 is smaller than a radius of the inner contour, R2.
On the other hand, as shown in FIG. 1B3, in a corner portion of the glass layer 105b, a radius of the outer contour, R3 is larger than a radius of the inner contour, R4.
It can be seen from FIGS. 1A3 and 1B3 that the area of the welded region between the glass layer and the substrate in the corner portion of the sealed structure is larger in the sealed structure of the embodiment of the present invention in which the radius of the outer contour is smaller than or equal to that of the inner contour in the corner portion of the welded region, than in the sealed structure of the comparison example. Therefore, application of one embodiment of the present invention enables the adhesion between the substrate and the glass layer in the corner portion of the sealed structure to be improved.
Further, it is preferable to decrease the radius of the outer contour in the corner portion of the welded region between the glass layer and the substrate to as close to zero as possible, because the area of the welded region in the corner portion of the sealed structure increases accordingly, and thus the adhesion between the glass layer and the substrate in the corner portion of the sealed structure further increases.
Respective plan views of sealed structures of other embodiments of the present invention are shown in FIGS. 2A to 2E.
The width of a corner portion of a glass layer 105c in a sealed structure shown in FIG. 2A is larger than that of a side portion of the same.
As shown in the glass layer 105c shown in FIG. 2A, the outer contour in a corner portion of a welded region between the glass layer and the substrate may have an angle. In the case where the outer contour has an angle, the angle is any of a right angle, an acute angle, and an obtuse angle.
The shape of the first surface of the substrate of the sealed structure of one embodiment of the present invention is not limited to quadrangle. As for the first substrate and the second substrate, the area of the first surface of the first substrate, which faces the first surface of the second substrate, is smaller than or equal to that of the first surface of the second substrate, and the first substrate has the corner portion. For example, as described below, a substrate the shape of the first surface of which is hexagonal can be used in one embodiment of the present invention.
In a sealed structure shown in FIG. 2B, a glass layer 135 is provided over a substrate 131 the shape of the first surface of which is hexagonal, along the periphery of the substrate 131. Then, the substrate 131 is attached to a counter substrate with the glass layer 135, so that a space 132 surrounded by the pair of substrates and the glass layer 135 is provided.
As for the glass layer 135, the width of a corner portion is larger than that of a side portion. Further, in the corner portion of the glass layer 135, the radius of the outer contour is smaller than that of the inner contour. Accordingly, the area of the welded region between the glass layer and the substrate in a corner portion of the sealed structure shown in FIG. 2B is large, and thus the adhesion between the glass layer and the substrate in the corner portion can be improved.
In a corner portion of a sealed structure shown in FIG. 2C, a glass layer 155a is provided over a substrate 151. A width of a corner portion of the glass layer 155a, W5 is larger than that of a side portion of the glass layer 155a, W6.
Likewise, in a corner portion of a sealed structure shown in FIG. 2D, a glass layer 155b is provided over a substrate 151. A width of a corner portion of the glass layer 155b, W7 is larger than that of a side portion of the glass layer 155b, W8.
Further, in a corner portion of a sealed structure shown in FIG. 2E, a glass layer 155c is provided over a substrate 151. A width of a corner portion of the glass layer 155c, W9 is larger than that of a side portion of the glass layer 155c, W10.
Accordingly, in any of the sealed structures shown in FIGS. 2C to 2E, the welded area between the glass layer and the substrate in the corner portion is large, so that the adhesion between the substrate and the glass layer in the corner portion can be improved.
In the case where the glass layer and the object to be sealed are provided over the same substrate, the order of formation of the object and the glass layer is not limited. The glass layer and the object may be provided over different substrates. Formation of the glass layer may involve a heat treatment; thus, it is preferable that the glass layer and the object be provided over different substrates in the case where the heat resistance of the object is low.
The glass layer can be formed of glass fit, for example. A glass ribbon can also be used. The glass frit or the glass ribbon contains at least a glass material.
The glass frit contains a glass material as a frit material; for example, magnesium oxide, calcium oxide, strontium oxide, barium oxide, cesium oxide, sodium oxide, potassium oxide, boron oxide, vanadium oxide, zinc oxide, tellurium oxide, aluminum oxide, silicon dioxide, lead oxide, tin oxide, phosphorus oxide, ruthenium oxide, rhodium oxide, iron oxide, copper oxide, manganese dioxide, molybdenum oxide, niobium oxide, titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide, lithium oxide, antimony oxide, lead borate glass, tin phosphate glass, vanadate glass, or borosilicate glass is contained. The glass frit preferably contains at least one or more kinds of transition metals to absorb infrared light.
One example of a method for manufacturing a sealed structure of one embodiment of the present invention is described below. In this embodiment, the glass layer 105a is formed of glass frit over the substrate 101 (see FIG. 1A1). Although the manufacturing process of an object to be sealed is omitted below, the object to be sealed is provided for the substrate 101 or the counter substrate.
First, frit paste is applied over the substrate 101 by a printing method such as screen printing or gravure printing, a dispensing method, or the like. In particular, use of the printing method such as screen printing or gravure printing is preferable because the fit paste can be formed easily into a desired shape. The difference between the shape of the resulting glass layer and the shape of this frit paste is small, and therefore the frit paste is preferably provided in its desired shape after attachment. In this embodiment, the frit paste is formed into a shape similar to that of the glass layer 105a, over the substrate 101.
The frit paste contains the frit material and a resin (also referred to as a binder) diluted by an organic solvent. As for the fit paste, a known material and a known composition can be used. For example, terpineol, n-butyl carbitol acetate, or the like can be used as the organic solvent and a cellulosic resin such as ethylcellulose can be used as the resin. Further, an absorbent of light with a wavelength of laser light may be contained in the frit paste.
Next, pre-baking is performed thereon to remove the resin or binder in the fit paste, so that the glass layer is formed.
The top surface of the glass layer is preferably flat to increase the adhesion to the counter substrate. Thus, a planarization treatment such as application of pressure may be performed thereon. The planarization treatment can be performed before or after the pre-baking.
Then, the substrate 101 and the counter substrate are disposed to face each other to make the glass layer and the counter substrate in close contact with each other, and the glass layer is irradiated with the laser light. For example, the beam diameter of the laser light is preferably greater than the width of the side portion of the glass layer (specifically, for example, equal to the width of the corner portion of the same), because the structure of one embodiment of the present invention can be easily obtained.
Through the above, the sealed structure in which the substrate 101 and the counter substrate are attached to each other with the glass layer 105a can be fabricated.
Further, for example, a defect portion where the glass layer does not exist in its predetermined region can be detected before attachment; thus, the substrate having this defect portion can be removed from the manufacturing process, thereby reducing execution of an unnecessary manufacturing process; alternatively, frit paste may be further applied over that substrate, and pre-baking may be performed thereon again, whereby the defect portion can be repaired. In this manner, according to one embodiment of the present invention, a reduction in yield can be suppressed by detecting a defect portion before attachment.
The sealing capability of the sealed structure of one embodiment of the present invention is high because the pair of substrates is attached with the glass layer as described above. In addition, the adhesion between the glass layer and the substrate is high in the corner portion because the area of the welded region between the glass layer and the substrate is large in the corner portion. Thus, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the sealed structure. Further, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion in the manufacturing process of the sealed structure, which leads to an improvement in yield.
Further, the sealed structure of one embodiment of the present invention is less likely to be deformed on attachment, and the shape of the glass layer after attachment can be predicted before the attachment, which enables the sealed structure to be manufactured at high yield. Further, the glass layer (or glass frit, frit paste, or the like for forming the glass layer) can be provided over the substrate, in its desired shape after the attachment, which leads to simplification of manufacturing of the sealed structure.
This embodiment can be combined with any other embodiment as appropriate.
Embodiment 2
In this embodiment, a light-emitting device of one embodiment of the present invention is described using FIGS. 3A and 3B.
FIG. 3A is a plan view of a light-emitting device of one embodiment of the present invention. FIG. 3B is a cross-sectional view taken along dashed-dotted line A-B in FIG. 3A.
The light-emitting device shown in FIGS. 3A and 3B includes a light-emitting portion 802 provided in a space 810 surrounded by a support substrate 801, a sealing substrate 806, and a glass layer 805.
A first surface of the support substrate 801 faces a first surface of the sealing substrate 806, and the glass layer 805 is provided along the periphery of the first surface of the sealing substrate 806. The sealing substrate 806 has a corner portion at each of four corners of the first surface. The area of the first surface of the sealing substrate 806 is smaller than that of the first surface of the support substrate 801.
In each corner portion of the glass layer 805, the radius of the outer contour is smaller than that of the inner contour. Further, in the glass layer 805, the width of the corner portion is larger than that of the side portion. In this embodiment, the shape of a welded region between the glass layer 805 and the support substrate 801 and the shape of a welded region between the glass layer 805 and the sealing substrate 806 are each the same as the top-surface shape of the glass layer 805 shown in FIG. 3A.
The light-emitting portion 802 includes a light-emitting element 130 (including a first electrode 118, an EL layer 120, and a second electrode 122). A bank 124 covers an end portion of the first electrode 118, and is provided with an opening in a position which overlaps with a light-emitting region of the light-emitting element 130.
The sealing capability of the light-emitting device is high because the light-emitting element 130 is provided in the space 810 surrounded by the pair of substrates and the glass layer 805. In addition, the adhesion between the substrate and the glass layer 805 in the corner portion of the light-emitting device can be increased because the welded area between the substrate and the glass layer 805 is large in the corner portion. Accordingly, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the light-emitting device.
For example, in the case where a plurality of light-emitting devices is manufactured over the same substrate, a trench is formed (scribed) in a top surface of the substrate and/or a counter substrate, and the substrates are cut along the trench, force tends to be concentrated on a corner portion of the light-emitting device, so that the pair of attached substrates tends to be detached from each other. However, in the light-emitting device of one embodiment of the present invention, detachment of the pair of substrates attached with the glass layer from each other can be suppressed even if force is concentrated on the corner portion of the light-emitting device, because the adhesion between the substrate and the glass layer in the corner portion is high. Accordingly, yield of the light-emitting device can be improved.
In the light-emitting device, the glass layer is used to attach the pair of substrates. The glass layer is less likely to be deformed on attachment, and thus the shape of the glass layer after attachment can be predicted before the attachment, which enables suppression of generation of such a defect that the glass layer does not exist in its predetermined region after the attachment and thus an object to be sealed cannot be sealed enough. Accordingly, a light-emitting device with high sealing capability can be manufactured at high yield. Further, the glass layer (or glass frit, frit paste, or the like for forming the glass layer) can be provided over the substrate, in its desired shape after attachment, which leads to simplification of manufacturing of the light-emitting device.
In the light-emitting device shown in FIG. 3A, a space is formed between the glass layer 805 and the light-emitting portion 802. A desiccant may be contained in the space. There is a case where heat of the irradiation with laser light leads to deterioration of an element or the like in the light-emitting portion 802; thus, a material functioning as a heat sink may be contained in the space.
In the light-emitting device described in this embodiment, the glass layer 805 is provided along the periphery of the sealing substrate 806. Therefore, the glass layer 805 is preferably formed over the sealing substrate 806 in its forming process. Further, the light-emitting element 130 is provided over the support substrate 801 in the light-emitting device described in this embodiment and there is a case where the light-emitting element 130 contains a material whose heat resistance is low. Therefore, also for suppressing deterioration of such an element in the step of pre-baking of frit paste or the like, it is preferable that the glass layer 805 be formed over the sealing substrate 806 in its forming process.
The support substrate 801 and the sealing substrate 806 are in direct contact with the glass layer 805 in this embodiment. However, embodiments of the present invention are not limited thereto; one or both of the substrates may be in indirect contact with the glass layer 805 through a film provided therebetween. Since irradiation with laser light is performed in the manufacturing process, the film provided between the substrate and the glass layer 805 is preferably formed using a high heat-resistant material. For example, an inorganic insulating film formed as a base film or an interlayer insulating film over the substrate may be in direct contact with the glass layer 805.
<Materials that can be Used for Light-Emitting Device of One Embodiment of the Present Invention>
Examples of materials that can be used for the light-emitting device of one embodiment of the present invention are described below. As to the glass layer, refer to the above-described description.
[Support Substrate 801, Sealing Substrate 806]
As materials for the substrates, glass, quartz, a resin, or the like can be used. Specifically, a material is used which has a heat resistance which is high enough to withstand the process temperature in the manufacturing process of the sealed structure, such as pre-baking or laser light irradiation. For the substrate on the side from which light from the light-emitting element is extracted, a material which transmits that light is used.
In order to suppress dispersion of an impurity included in the support substrate 801 into any element provided over the support substrate 801, to provide an insulating layer on the top surface of the support substrate 801 or to perform a heat treatment on the support substrate 801 is preferable.
[Light-Emitting Element 130]
There is no limitation on the method for driving the light-emitting element 130; either an active matrix method or a passive matrix method can be used. Further, any of a top emission structure, a bottom emission structure, and a dual emission structure can be used.
A light-emitting element with a bottom emission structure is used as an example for description in this embodiment.
As examples of a light-transmitting material for the first electrode 118, indium oxide, indium tin oxide (ITO), indium zinc oxide, zinc oxide, zinc oxide to which gallium is added, and the like can be given.
Further, for the first electrode 118, a metal material such as gold, platinum, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, or titanium can also be used. A nitride of the metal material (e.g., titanium nitride) or the like may also be used. Graphene or the like may also be used. In the case of using the metal material (or the nitride thereof), the first electrode is preferably formed to be thin so as to be able to transmit light.
The EL layer 120 includes at least a light-emitting layer. The light-emitting layer contains a light-emitting organic compound. The EL layer 120 can have a stacked-layer structure in which a layer containing a substance having a high electron-transport property, a layer containing a substance having a high hole-transport property, a layer containing a substance having a high electron-injection property, a layer containing a substance having a high hole-injection property, a layer containing a bipolar substance (a substance having a high electron-transport property and a high hole-transport property), and the like are combined as appropriate to the above-described light-emitting layer. Examples of the structure of the EL layer are described in detail in Embodiment 5.
The second electrode 122 is provided on the side opposite to the light extraction side and is formed using a reflective material. As the reflective material, a metal material such as aluminum, gold, platinum, silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium can be used. Any of the following can also be used: an alloy containing aluminum (aluminum alloy) such as an alloy of aluminum and titanium, an alloy of aluminum and nickel, and an alloy of aluminum and neodymium; and an alloy containing silver such as an alloy of silver and copper. The alloy of silver and copper is preferable because of its high heat resistance. Lanthanum, neodymium, germanium, or the like may be added to the metal material or alloy.
[Bank 124]
As a material for the bank 124, a resin or an inorganic insulating material can be used. As the resin, for example, a polyimide resin, a polyamide resin, an acrylic resin, a siloxane resin, an epoxy resin, or a phenol resin can be used.
In particular, either a negative photosensitive resin or a positive photosensitive resin is preferably used for easy formation of the bank 124.
The bank 124 is provided so as to cover an end portion of the first electrode 118. The bank 124 is preferably formed to have a curved surface with curvature in its upper end portion or lower end portion in order to improve the coverage with the EL layer 120 or the second electrode 122 which is formed over the bank 124.
There is no particular limitation to the method for forming the bank; a photolithography method, a sputtering method, an evaporation method, a droplet discharging method (e.g., an inkjet method), a printing method (e.g., a screen printing method or an off-set printing method), or the like may be used.
[Space 810]
The space 810 may be filled with an inert gas such as a rare gas or a nitrogen gas or a solid such as an organic resin, or may be in a reduced pressure atmosphere. A dry agent may be provided in the space 810. For the dry agent, a substance which absorbs moisture and the like by chemical adsorption or a substance which adsorbs moisture and the like by physical adsorption can be used. An oxide of an alkali metal, an oxide of an alkaline earth metal (e.g., calcium oxide or barium oxide), sulfate, a metal halide, perchlorate, zeolite, and silica gel can be given as examples thereof.
This embodiment can be combined with any other embodiment as appropriate.
Embodiment 3
In this embodiment, a light-emitting device of one embodiment of the present invention is described using. FIGS. 4A and 4B. FIG. 4A is a plan view of a light-emitting device of one embodiment of the present invention. FIG. 4B is a cross-sectional view taken along dashed-dotted line C-D in FIG. 4A.
In a light-emitting device of this embodiment, a support substrate 801 is attached to a sealing substrate 806 with a glass layer 805. A first surface of the support substrate 801 faces a first surface of the sealing substrate 806, and the glass layer 805 is provided along the periphery of the first surface of the sealing substrate 806. The first surface of the sealing substrate 806 has a depression. The first surface of the sealing substrate 806 has a corner portion. The area of the first surface of the sealing substrate 806 is smaller than that of the first surface of the support substrate 801.
The width of a corner portion of the glass layer 805 is larger than that of a side portion of the same. Further, in the corner portion of the glass layer 805, the outer contour has an angle, specifically, an obtuse angle. In this embodiment, the shape of a welded region between the glass layer 805 and the sealing substrate 806 is the same as the top surface of the glass layer 805 shown in FIG. 4A.
In the light-emitting device of this embodiment, a light-emitting element 130 (a first electrode 118, an EL layer 120, and a second electrode 122) is provided in a space 810 surrounded by the support substrate 801, the sealing substrate 806, and the glass layer 805. The light-emitting element 130 has a bottom emission structure; specifically, the first electrode 118 is provided over the support substrate 801, the EL layer 120 is provided over the first electrode 118, and the second electrode 122 is provided over the EL layer 120.
The sealing capability of the light-emitting device is high because the light-emitting element 130 is provide in the space 810 surrounded by the pair of substrates and the glass layer 805. In addition, the adhesion between the substrate and the glass layer 805 in a corner portion of the light-emitting device can be increased because the welded area between the substrate and the glass layer 805 is large in the corner portion. Accordingly, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the light-emitting device.
In the light-emitting device, the glass layer is used to attach the pair of substrates. The glass layer is less likely to be deformed on attachment, and thus the shape of the glass layer after attachment can be predicted before the attachment, which enables suppression of generation of such a defect that the glass layer does not exist in its predetermined region after the attachment and thus an object to be sealed cannot be sealed enough. Accordingly, a light-emitting device with high sealing capability can be manufactured at high yield. Further, the glass layer (or glass frit, frit paste, or the like for forming the glass layer) can be provided over the substrate, in its desired shape after attachment, which leads to simplification of manufacturing of the light-emitting device.
A first terminal 809a is electrically connected to an auxiliary wiring 163 and the first electrode 118. An insulating layer 125 is provided in a region which overlaps with the auxiliary wiring 163 and the first terminal 809a over the first electrode 118. The first terminal 809a is electrically isolated from the second electrode 122 by the insulating layer 125. A second terminal 809b is electrically connected to the second electrode 122. In this embodiment, the first electrode 118 is formed over the auxiliary wiring 163; however, the auxiliary wiring 163 may be formed over the first electrode 118.
The organic EL element emits light in a region with a refractive index higher than that of the air; thus, when light is extracted to the air, total reflection occurs in the organic EL element or at the interface between the organic EL element and the air under a certain condition, which results in a light extraction efficiency of lower than 100%.
Specifically, supposing that the refractive index of a medium A is higher than the refractive index of a medium B and the refractive index of the medium B is lower than the refractive index of the EL layer, when light enters the medium B from the medium A, total reflection occurs in some cases depending on its incident angle.
In that case, it is preferable that an uneven surface structure be provided at the interface between the medium A and the medium B. With such a structure, such phenomenon that light entering the medium B from the medium A at an incidence angle exceeding a critical angle is totally reflected and the wave of the light propagates inside the light-emitting device to lower the light extraction efficiency can be suppressed.
For example, an uneven surface structure 161a is preferably provided in the interface between the support substrate 801 and the air. The refractive index of the support substrate 801 is higher than the refractive index of the air. Therefore, with the uneven surface structure 161a provided in the interface between the air and the support substrate 801, light which cannot be extracted to the air owing to total reflection can be reduced, whereby the light extraction efficiency of the light-emitting device can be improved.
Further, an uneven surface structure 161b is preferably provided in the interface between the light-emitting element 130 and the support substrate 801.
However, in the organic EL element, unevenness of the first electrode 118 might lead to occurrence of leakage current in the EL layer 120 formed over the first electrode 118. Therefore, in this embodiment, a planarization layer 162 having a refractive index higher than or equal to that of the EL layer 120 is provided in contact with the uneven surface structure 161b. Accordingly, the first electrode 118 can be provided to be a flat film, and thus occurrence of leakage current in the EL layer due to the unevenness of the first electrode 118 can be suppressed. Further, owing to the uneven surface structure 161b in the interface between the planarization layer 162 and the support substrate 801, light which cannot be extracted to the air due to total reflection can be reduced, whereby the light extraction efficiency of the light-emitting device can be increased.
In FIG. 4B, the support substrate 801, the uneven surface structure 161a, and the uneven surface structure 161b are different components; however, embodiments of the present invention are not limited thereto. Two or all of these may be formed as one component.
Although the light-emitting device shown in FIG. 4A is octagonal, embodiments of the present invention are not limited thereto. The shape of the light-emitting device may be any other polygonal or a shape having a curved portion as long as it is a shape having a corner portion. As the shape of the light-emitting device, a triangle, a quadrangle, a regular hexagon, or the like is particularly preferable. The reason for this is that a plurality of light-emitting devices can be provided with a redundant space as little as possible in a limited area; a light-emitting device can be formed using a limited substrate area efficiently. Further, the number of light-emitting elements in the light-emitting device is not limited to one; a plurality of light-emitting elements may be provided therein.
<Materials that can be Used for Light-Emitting Device of One Embodiment of the Present Invention>
Examples of materials that can be used for the light-emitting device of one embodiment of the present invention are described below. As for the substrate, the light-emitting element, the sealant, and the space, their respective materials described above in the embodiments can be used.
[Insulating Layer 125]
The insulating layer 125 can be formed using a material similar to any of the materials for the bank 124 described above in the embodiments.
[Auxiliary Wiring 163, First Terminal 809a, and Second Terminal 809b]
The auxiliary wiring 163, the first terminal 809a, and the second terminal 809b are preferably formed by the same step(s) (at the same time), because the number of manufacturing steps of the light-emitting device can be reduced. For example, they can be formed to have a single-layer structure or a stacked-layered structure using a material selected from copper (Cu), titanium (Ti), tantalum (Ta), tungsten (W), molybdenum (Mo), chromium (Cr), neodymium (Nd), scandium (Sc), and nickel (Ni) or an alloy material containing any of these materials as its main component.
[Uneven Surface Structure 161a, 161b]
The shape of the unevenness does not necessarily have an order of regularity. When the shape of the unevenness is periodic, the unevenness functions as a diffraction grating depending on the size of the unevenness, so that an interference effect is increased and light with a certain wavelength is more likely to be extracted to the air. Therefore, it is preferable that the shape of the unevenness be not periodic.
There is no particular limitation on the shape of bottom surface of the unevenness; for example, the shape may be a polygon such a triangle or a quadrangle, a circle, or the like. When the shape of bottom surface of the unevenness has an order of regularity, the unevenness is preferably provided so that gaps are not formed between adjacent portions of the unevenness. A regular hexagon is given as an example of a preferable shape of the bottom surface.
There is no particular limitation on the cross-sectional shape of the unevenness in the direction perpendicular to the bottom surface; for example, a hemisphere or a shape with a vertex such as a circular cone, a pyramid (e.g., a triangular pyramid or a square pyramid), or an umbrella shape can be used.
In particular, the size or the height of the unevenness is preferably 1 μm or more, because influence of interference of light can be suppressed.
The uneven surface structure 161a, 161b can be provided directly on/underneath the support substrate 801. As the method therefor, for example, an etching method, a sand blasting method, a microblast processing method, a droplet discharge method, a printing method (screen printing or offset printing by which a pattern is formed), a coating method such as a spin coating method, a dipping method, a dispenser method, an imprint method, a nanoimprint method, or the like can be used as appropriate.
As the material of the uneven surface structure 161a, 161b, for example, resin can be used; specifically, a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), a polyacrylonitrile resin, a polyimide resin, an acrylic (polymethylmethacrylate) resin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, a polyamide resin, a cyclic olefin-based resin, a cycloolefin resin, a polystyrene resin, a polyamide imide resin, a polyvinylchloride resin, or the like can be used. A resin in which two or more kinds of the above resins are combined may be used. It is preferable to use an acrylic resin because of its high visible light transmittance. A cyclic olefin-based resin and a cycloolefin resin are each preferable because they have high visible light transmittance and high heat resistance.
For the uneven surface structure 161a, 161b, a hemispherical lens, a micro lens array, a film provided with an uneven surface structure, a light diffusing film, or the like can be used. For example, the lens or film can be attached over/below the support substrate 801 with an adhesive or the like with substantially the same refractive index as the lens or film, so that the uneven surface structure 161a, 161b can be formed.
[Planarization Layer 162]
The planarization layer 162 is more flat in its one surface which is in contact with the first electrode 118 than in its other surface which is in contact with the uneven surface structure 161b. Therefore, the first electrode 118 can be formed to be flat. As a result, generation of leakage current in the EL layer 120 due to unevenness of the first electrode 118 can be suppressed.
As a material of the planarization layer 162, liquid, resin, or the like having a high refractive index can be used. The planarization layer 162 has a light-transmitting property. As examples of the resin having a high refractive index, resin containing bromine, resin containing sulfur, and the like are given; for example, a sulfur-containing polyimide resin, an episulfide resin, a thiourethane resin, a brominated aromatic resin, or the like can be used. Polyethylene terephthalate (PET), triacetyl cellulose (TAC), or the like can also be used. As the liquid having high refractive index, contact liquid (refractive liquid) containing sulfur and methylene iodide, or the like can be used. Any of a variety of methods suitable for the material may be employed for forming the planarization layer 162. For example, the above resin is deposited by a spin coating method and is cured by heat or light. The material and the formation method can be selected as appropriate in consideration of the adhesion strength, ease of processing, or the like.
This embodiment can be combined with any other embodiment as appropriate.
Embodiment 4
In this embodiment, a light-emitting device of one embodiment of the present invention is described using FIGS. 5A and 5B. FIG. 5A is a plan view of a light-emitting device of one embodiment of the present invention and FIG. 5B is a cross-sectional view taken along dashed-dotted line E-F in FIG. 5A.
An active matrix light-emitting device according to this embodiment includes, over a support substrate 801, a light-emitting portion 802, a driver circuit portion 803 (gate side driver circuit portion), a driver circuit portion 804 (source side drive circuit portion), and a glass layer 805. The light-emitting portion 802 and the driver circuit portions 803 and 804 are sealed in a space 810 formed by the support substrate 801, a sealing substrate 806, and the glass layer 805.
A first surface of the support substrate 801 faces a first surface of the sealing substrate 806, and the glass layer 805 is provided along the periphery of the first surface of the sealing substrate 806. The first surface of the sealing substrate 806 has a corner portion. The area of the first surface of the sealing substrate 806 is smaller than that of the first surface of the support substrate 801.
In a corner portion of the glass layer 805, the radius of the outer contour is smaller than that of the inner contour. Further, the width of the corner portion of the glass layer 805 is larger than that of a side portion of the same. In this embodiment, the shape of a welded region between the glass layer 805 and the sealing substrate 806 is the same as that of the top surface of the glass layer 805 shown in FIG. 5A.
The light-emitting portion 802 shown in FIG. 5B includes a plurality of light-emitting units each including a switching transistor 140a, a current control transistor 140b, and a second electrode 122 electrically connected to a wiring (a source electrode or a drain electrode) of the transistor 140b. 
A light-emitting element 130 has a top emission structure, including a first electrode 118, an EL layer 120, and the second electrode 122. Further, a bank 124 is formed to cover an end portion of the second electrode 122.
The sealing capability of the light-emitting device is high because the light-emitting element 130 is provide in the space 810 surrounded by the pair of substrates and the glass layer 805. In addition, the adhesion between the substrate and the glass layer 805 in the corner portion of the light-emitting device can be increased because the welded area between the substrate and the glass layer 805 is large in the corner portion. Accordingly, detachment of the pair of attached substrates from each other can be suppressed even if force is concentrated on the corner portion of the light-emitting device.
Further, in the light-emitting device, the glass layer is used to attach the pair of substrates. The glass layer is less likely to be deformed on attachment, and thus the shape of the glass layer after attachment can be predicted before the attachment, which enables suppression of generation of such a defect that the glass layer does not exist in, its predetermined region after the attachment and thus an object to be sealed cannot be sealed enough. Accordingly, a light-emitting device with high sealing capability can be manufactured at high yield. Further, the glass layer (or glass frit, frit paste, or the like for forming the glass layer) can be provided over the substrate, in its desired shape after attachment, which leads to simplification of manufacturing of the light-emitting device.
Over the support substrate 801, a lead wiring 809 for connecting an external input terminal through which a signal (e.g., a video signal, a clock signal, a start signal, or a reset signal) or a potential from the outside is transmitted to the driver circuit portion 803, 804 is provided. Here, an example thereof is described in which a flexible printed circuit (FPC) 808 is provided as the external input terminal. A printed wiring board (PWB) may be attached to the FPC 808. In this specification, the light-emitting device includes in its category not only the light-emitting device itself but also the light-emitting device provided with an FPC or a PWB.
The driver circuit portion 803, 804 includes a plurality, of transistors. An example in which the driver circuit portion 803 includes a CMOS circuit which is a combination of an n-channel transistor 142 and a p-channel transistor 143 is shown in FIG. 5B. A circuit included in the driver circuit portion can be formed using any type of circuit such as a CMOS circuit, a PMOS circuit, or an NMOS circuit. In this embodiment, a driver-integrated type in which a driver circuit and a light-emitting portion are formed over the same substrate is described; however, embodiments of the present invention are not limited to this structure, in which a driver circuit can be formed over a substrate that is different from a substrate over which a light-emitting portion is formed.
To prevent increase in the number of manufacturing steps, the lead wiring 809 is preferably formed using the same material and the same step(s) as those of the electrode or the wiring in the light-emitting portion or the driver circuit portion.
Described in this embodiment is an example in which the lead wiring 809 is formed using the same material and the same step(s) as those of the gate electrode of the transistor included in the light-emitting portion 802 and the driver circuit portion 803.
In FIG. 5B, the glass layer 805 is in contact with a first insulating layer 114 over the lead wiring 809. The adhesion of the glass layer 805 to metal is low in some cases. Therefore, the glass layer 805 is preferably in contact with an inorganic insulating film over the lead wiring 809; such a structure enables a light-emitting device with high sealing capability and high reliability to be achieved. As examples of the inorganic insulating film, an oxide film of a metal or a semiconductor, a nitride film of a metal or a semiconductor, and a oxynitride film of a metal or a semiconductor are given; specifically, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon nitride oxide film, an aluminum oxide film, a titanium oxide film, and the like can be given.
<Materials that can be Used for Light-Emitting Device of One Embodiment of the Present Invention>
Examples of materials that can be used for the light-emitting device of one embodiment of the present invention are described below. As for the substrate, the light-emitting element, the glass layer, the space, and the bank, their respective materials described above in the embodiments can be used.
[Transistor]
There is no particular limitation on the structure of the transistor (e.g., the transistor 140a, 140b, 142, or 143) used in the light-emitting device of one embodiment of the present invention. A top-gate transistor may be used, or a bottom-gate transistor such as an inverted staggered transistor may be used. A channel-etched type or a channel-stop (channel-protective) type may also be employed. In addition, there is no particular limitation on materials for the transistor.
The gate electrode can be formed to have a single-layer structure or a stacked-layer structure using any of metal materials such as molybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, and scandium, or an alloy material which contains any of these elements, for example. A structure may be employed in which a film of a high-melting-point metal such as titanium, molybdenum, or tungsten, or a nitride film of any of these metals (a titanium nitride film, a molybdenum nitride film, or a tungsten nitride film) is stacked either or both of over and under a metal film of aluminum, copper, or the like. For example, a three layer structure consisting of a titanium film, an aluminum film or a copper film, and a titanium film is preferably employed.
The gate insulating layer is formed using a material which transmits light from the light-emitting element. The gate insulating layer can be formed to have a single-layer structure or a stacked-layer structure using any of silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, and aluminum oxide by a plasma-enhanced CVD method, a sputtering method, or the like, for example.
The semiconductor layer can be formed using a silicon semiconductor or an oxide semiconductor. As examples of the silicon semiconductor, single crystal silicon, polycrystalline silicon, and the like can be given. As the oxide semiconductor, an In—Ga—Zn-based metal oxide or the like can be used as appropriate. The semiconductor layer is preferably formed using an In—Ga—Zn-based metal oxide that is an oxide semiconductor such that the semiconductor layer is a semiconductor layer whose off-state current is small, because the off-state leakage current of the light-emitting element 130 can be reduced.
As the source electrode layer and the drain electrode layer, for example, a metal film containing an element selected from aluminum, chromium, copper, tantalum, titanium, molybdenum, and tungsten; a metal nitride film containing any of the above elements (e.g., a titanium nitride film, a molybdenum nitride film, or a tungsten nitride film); or the like can be used. A structure may also be used in which a film of a high-melting-point metal such as titanium, molybdenum, or tungsten, or a nitride film of any of these metals (a titanium nitride film, a molybdenum nitride film, or a tungsten nitride film) is stacked on either or both of over and under a metal film of aluminum, copper, or the like. For example, a three-layer structure consisting of a titanium film, an aluminum film or a copper film, and a titanium film is preferably used.
Further or alternatively, the source electrode layer and the drain electrode layer may be formed using a conductive metal oxide. As the conductive metal oxide, indium oxide (In2O3 or the like), tin oxide (SnO2 or the like), zinc oxide (ZnO), ITO, indium oxide-zinc oxide (In2O3—ZnO or the like), or any of these metal oxide materials in which silicon oxide is contained can be used.
[First Insulating Layer 114, Second Insulating Layer 116]
The first insulating layer 114 and a second insulating layer 116 are formed using materials which transmit light from the light-emitting element.
The first insulating layer 114 has an effect of preventing diffusion of impurities into the semiconductor included in the transistor. As the first insulating layer 114, an inorganic insulating film such as a silicon oxide film, a silicon oxynitride film, or an aluminum oxide film can be used.
As the second insulating layer 116, an insulating film with a planarization function is preferably selected in order to reduce surface unevenness due to a color filter or the transistor. For example, an organic material such as a polyimide resin, an acrylic resin, or a benzocyclobutene resin can be used. Other than such organic materials, it is also possible to use a low-dielectric constant material (a low-k material) or the like. The second insulating layer 116 may be formed by stacking a plurality of insulating films formed using any of these materials.
[Color Filter 166, Black Matrix 164]
For the sealing substrate 806, a color filter 166 that is a coloring layer is provided to overlap with (the light-emitting region of) the light-emitting element 130. The color filter 166 is provided in order to control the color of light emitted from the light-emitting element 130. For example, in a full-color display device using white light-emitting elements, a plurality of light-emitting units provided with color filters of different colors are used. In that case, three colors, red (R), green (G), and blue (B), may be used, or four colors, red (R), green (G), blue (B), and yellow (Y), may be used.
Further, a black matrix 164 is provided between the adjacent color filters 166 (not to overlap with the light-emitting region of the light-emitting element 130). The black matrix 164 shields the light-emitting unit from light emitted from the light-emitting element 130 in its adjacent light-emitting unit and thereby prevents color mixture between the adjacent light-emitting units. Here, the color filter 166 is provided so that its end portion overlaps with the black matrix 164, whereby light leakage can be suppressed. The black matrix 164 can be formed using a material which shields light emitted from the light-emitting element 130, for example, metal or resin. The black matrix 164 may be provided in a region other than the light-emitting portion 802, such as the driver circuit portion 803.
Further, an overcoat layer 168 is formed to cover the color filter 166 and the black matrix 164. The overcoat layer 168 is formed using a material which transmits light emitted from the light-emitting element 130; for example, an inorganic insulating film or an organic insulating film can be used. The overcoat layer 168 is not necessarily provided unless needed.
In this embodiment, a light-emitting device using a color filter method is described as an example; however, embodiments of the present invention are not limited thereto. For example, a separate coloring method or a color conversion method may be used.
This embodiment can be combined with any other embodiment as appropriate.
Embodiment 5
In this embodiment, structural examples of an EL layer applicable to a light-emitting device of one embodiment of the present invention are described using FIGS. 6A to 6C.
A known substance can be used for the EL layer; either a low molecular compound or a high molecular compound can be used. The constituent substance of the EL layer is not limited to an organic compound; an inorganic compound may be contained.
In FIG. 6A, an EL layer 120 is provided between a first electrode 118 and a second electrode 122. In the EL layer 120 in FIG. 6A, a hole-injection layer 701, a hole-transport layer 702, a light-emitting layer 703, an electron-transport layer 704, and an electron-injection layer 705 are stacked in this order from the first electrode 118 side.
A plurality of EL layers may be stacked between the first electrode 118 and the second electrode 122 as shown in FIG. 6B. In that case, a charge generation layer 709 is preferably provided between a first EL layer 120a and a second EL layer 120b which are stacked. In a light-emitting element having such a structure, problems such as energy transfer and quenching less occur, which enables expansion in the choice of materials, thereby achieving a light-emitting element which has both high light emission efficiency and long lifetime easily. Moreover, phosphorescence and fluorescence can be obtained easily from one EL layer and the other EL layer, respectively. This structure can be combined with the above-described EL layer structure.
Further, by forming EL layers to emit light of different colors from each other, a light-emitting element can provide light emission of a desired color as a whole. For example, by forming a light-emitting element having two EL layers such that the emission color of the first EL layer and the emission color of the second EL layer are colors complementary to each other, the light-emitting element can provide white light emission as a whole. The “colors complementary to each other” means colors which become an achromatic color by mixture of them. That is, once respective light emitted from substances whose emission colors are complementary to each other is mixed together, white emission color can be obtained. This applies to a light-emitting element having three or more EL layers.
As shown in FIG. 6C, the EL layer 120 may include the hole-injection layer 701, the hole-transport layer 702, the light-emitting layer 703, the electron-transport layer 704, an electron-injection buffer layer 706, an electron-relay layer 707, and a composite material layer 708 which is in contact with the second electrode 122, between the first electrode 118 and the second electrode 122.
It is preferable to provide the composite material layer 708 which is in contact with the second electrode 122, because damage on the EL layer 120 particularly in formation of the second electrode 122 by a sputtering method can be attenuated.
Further, by the electron-injection buffer layer 706, an injection barrier between the composite material layer 708 and the electron-transport layer 704 can be reduced; thus, electrons generated in the composite material layer 708 can be easily injected to the electron-transport layer 704.
Furthermore, the electron-relay layer 707 is preferably formed between the electron-injection buffer layer 706 and the composite material layer 708. The electron-relay layer 707 is not necessarily provided; however, the electron-relay layer 707 having a high electron-transport property enables electrons to be rapidly transported to the electron-injection buffer layer 706.
The structure in which the electron-relay layer 707 is sandwiched between the composite material layer 708 and the electron-injection buffer layer 706 is a structure in which the acceptor substance contained in the composite material layer 708 and the donor substance contained in the electron-injection buffer layer 706 are less likely to interact with each other, and thus their functions hardly interfere with each other. Accordingly, an increase in drive voltage can be suppressed.
Examples of respective materials which can be used for the layers are described below. Each layer is not limited to a single layer, but may be a stack of two or more layers.
<Hole-Injection Layer 701>
The hole-injection layer 701 is a layer containing a substance having a high hole-injection property.
As the substance having a high hole-injection property, for example, a metal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide, tungsten oxide, or manganese oxide, a phthalocyanine-based compound such as phthalocyanine (H2Pc) and copper phthalocyanine (CuPc), or the like can be used.
Further, a high molecular compound such as poly(N-vinylcarbazole) (abbreviation: PVK) or poly(4-vinyltriphenylamine) (abbreviation: PVTPA), or a high molecular compound to which acid is added, such as poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS) can also be used.
In particular, for the hole-injection layer 701, a composite material containing an organic compound having a high hole-transport property and an electron acceptor (acceptor) is preferably used. Such a composite material has an excellent hole-injection and hole-transport properties because holes are generated in the organic compound by the electron acceptor. Such a composite material enables the hole-transport capability from the first electrode 118 to the EL layer 120 to be increased, whereby the drive voltage of the light-emitting element can be decreased.
Such a composite material can be formed by co-evaporation of an organic compound having a high hole-transport property and an electron acceptor. The hole-injection layer 701 is not limited to a structure in which an organic compound having a high hole-transport property and an electron acceptor are contained in the same film, but may be a structure in which a layer containing an organic compound having a high hole-transport property and a layer containing an electron acceptor are stacked. Specifically, a layer containing an electron acceptor is in contact with the first electrode 118.
The organic compound used in the composite material is an organic compound whose hole-transport property is higher than its electron-transport property; particularly, it is preferable that the hole mobility of the organic compound be greater than or equal to 10−6 cm2/Vs. As the organic compound for the composite material, any of a variety of compounds including an aromatic amine compound, a carbazole derivative, an aromatic hydrocarbon compound, and a high molecular compound can be used.
As examples of the aromatic amine compound, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), and the like can be given.
As examples of the carbazole derivative, 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBF), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), and the like can be given.
As examples of the aromatic hydrocarbon compound, 2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA), 9,10-diphenylanthracene (abbreviation: DPAnth), and the like can be given.
As examples of the high molecular compound, PVK, PVTPA, and the like can be given.
As examples of the electron acceptor for the composite material, a transition metal oxide or an oxide of a metal belonging to Group 4 to Group 8 of the periodic table can be given. Specifically, molybdenum oxide is preferable. Molybdenum oxide is easy to handle because of its stability in the air and its low hygroscopic property.
<Hole-Transport Layer 702>
The hole-transport layer 702 is a layer which contains a substance having a high hole-transport property.
The substance having a high hole-transport property is a substance whose hole-transport property is higher than its electron-transport property; particularly, it is preferable that the hole mobility of the substance having a high hole-transport property be greater than or equal to 10−6 cm2/Vs. For example, any of a variety of compounds such as an aromatic amine compound such as NPB or BPAFLP, a carbazole derivative such as CBP, CzPA, or PCzPA, an aromatic hydrocarbon compound such as t-BuDNA, DNA, or DPAnth, and a high molecular compound such as PVK or PVTPA can be used.
<Light-Emitting Layer 703>
For the light-emitting layer 703, a fluorescent compound that exhibits fluorescence or a phosphorescent compound that exhibits phosphorescence can be used.
As examples of the fluorescent compound for the light-emitting layer 703, N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine (abbreviation: YGA2S), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), rubrene, and the like can be given.
As examples of the phosphorescent compound for the light-emitting layer 703, metallo-organic complexes such as bis[2-(4′,6′-difluorophenyl)pyridinato-N,C2′]iridium (III)picolinate (abbreviation: FIrpic), tris(2-phenylpyridinato-N,C2′)iridium(III) (abbreviation: Ir(ppy)3), and (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: Ir(mppr-Me)2(acac)) can be given.
The light-emitting layer 703 may have a structure in which any of the above-described light-emitting organic compounds (a light-emitting substance or a guest material) is dispersed in another substance (a host material). As the host material, any of a variety of materials can be used, and it is preferable to use a substance which has a lowest unoccupied molecular orbital level (LUMO level) higher than that of the guest material and has a highest occupied molecular orbital level (HOMO level) lower than that of the guest material.
With a structure in which a guest material is dispersed in a host material, crystallization of the light-emitting layer 703 can be suppressed. Further, concentration quenching due to high concentration of the guest material can be suppressed.
As the host material, specifically, a metal complex such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq) or bis(2-methyl-8-quinolinolato) (4-phenylphenolato)aluminum(III) (abbreviation: BAlq), a heterocyclic compound such as 3-(4′-tert-butylphenyl)-4-phenyl-5-(4′′-biphenyl)-1,2,4-triazole (abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen), or bathocuproine (abbreviation: BCP), a condensed aromatic compound such as CzPA, DNA, t-BuDNA, or DPAnth, an aromatic amine compound such as NPB, or the like can be used.
Plural kinds of materials can be used for the host material. For example, to suppress crystallization, a substance such as rubrene which suppresses crystallization, may be further added. In addition, NPB, Alq, or the like may be further added in order to efficiently transfer energy to the guest material.
Further, by providing a plurality of light-emitting layers such that their respective emission colors are different from each other, light emission of a desired color can be obtained from the light-emitting element as a whole. For example, by using first and second light-emitting layers whose emission colors are complementary to each other in a light-emitting element having the two light-emitting layers, the light-emitting element can be made to emit white light as a whole. The same applies to a light-emitting element having three or more light-emitting layers.
<Electron-Transport Layer 704>
The electron-transport layer 704 is a layer which contains a substance having a high electron-transport property.
The substance having a high electron-transport property is an organic compound whose electron-transport property is higher than its hole-transport property; particularly, it is preferable that the electron mobility of the substance having a high electron-transport property be greater than or equal to 10−6 cm2/Vs.
As the substance having a high electron-transport property, a metal complex having a quinoline skeleton or a benzoquinoline skeleton, such as Alq or BAlq, a metal complex having an oxazole-based or thiazole-based ligand, such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)2) or bis[2-(2-hydroxyphenyl)-benzothiazolato]zinc (abbreviation: Zn(BTZ)2), or the like can be used. Further, TAZ, BPhen, BCP, or the like can also be used.
<Electron-Injection Layer 705>
The electron-injection layer 705 is a layer which contains a substance having a high electron-injection property.
As the substance having a high electron-injection property, an alkali metal such as lithium, an alkaline earth metal such as cesium or calcium, or a compound thereof such as lithium fluoride, cesium fluoride, calcium fluoride, or lithium oxide can be used. Further, a rare earth metal compound such as erbium fluoride can also be used. Any of the above-described substances for the electron-transport layer 704 can also be used.
The hole-injection layer 701, the hole-transport layer 702, the light-emitting layer 703, the electron-transport layer 704, and the electron-injection layer 705 which are described above can each be formed by an evaporation method (e.g., a vacuum evaporation method), an ink-jet method, a coating method, or the like.
<Charge Generation Layer 709>
The charge generation layer 709 shown in FIG. 6B can be formed using the above-described composite material. The charge generation layer 709 may have a stacked-layer structure including a layer containing the composite material and a layer containing another material. In that case, as the layer containing another material, a layer containing an electron donating substance and a substance having a high electron-transport property, a layer formed of a transparent conductive film, or the like can be used.
<Composite Material Layer 708>
For the composite material layer 708 shown in FIG. 6C, the above-described composite material containing an organic compound having a high hole-transport property and an electron acceptor can be used.
<Electron-Injection Buffer Layer 706>
For the electron-injection buffer layer 706, a substance having a high electron-injection property, such as an alkali metal, an alkaline earth metal, a rare earth metal, or a compound of any of the above metals (including an oxide such as lithium oxide, a halide, and a carbonate such as lithium carbonate or cesium carbonate) can be used.
Further, in the case where the electron-injection buffer layer 706 contains a substance having a high electron-transport property and a donor substance, the donor substance is preferably added so that the mass ratio of the donor substance to the substance having a high electron-transport property is from 0.001:1 to 0.1:1. As the donor substance, an organic compound such as tetrathianaphthacene (abbreviation: TTN), nickelocene, or decamethylnickelocene can be used as well as an alkali metal, an alkaline earth metal, a rare earth metal, or a compound of any of the above metals. As the substance having a high electron-injection property, a material similar to any of the above-described materials for the electron-transport layer 704 can be used.
<Electron-Relay Layer 707>
The electron-relay layer 707 contains a substance having a high electron-transport property and is formed so that the LUMO level of the substance having a high electron-transport property is located between the LUMO level of the acceptor substance contained in the composite material layer 708 and the LUMO level of the substance having a high electron-transport property contained in the electron-transport layer 704. In the case where the electron-relay layer 707 contains a donor substance, the donor level of the donor substance is adjusted so as to be located between the LUMO level of the acceptor material contained in the composite material layer 708 and the LUMO level of the substance having a high electron-transport property contained in the electron-transport layer 704. As for the specific value of the energy level, the LUMO level of the substance having a high electron-transport property contained in the electron-relay layer 707 is preferably greater than or equal to −5.0 eV, more preferably greater than or equal to −5.0 eV and less than or equal to −3.0 eV.
As the substance having a high electron-transport property contained in the electron-relay layer 707, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.
As examples of the phthalocyanine-based material for the electron-relay layer 707, specifically, CuPc, PhO-VOPc (Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine), and the like can be given.
As the metal complex having a metal-oxygen bond and an aromatic ligand for the electron-relay layer 707, a metal complex having a metal-oxygen double bond is preferably used. The metal-oxygen double bond has an acceptor property (properties of high electron acceptability), which facilitate transfer (donation and acceptance) of electrons.
As the metal complex having a metal-oxygen bond and an aromatic ligand, a phthalocyanine-based material is preferable. In particular, a material in which a metal-oxygen double bond is more likely to act on another molecular in terms of a molecular structure and having a high acceptor property is preferable.
As the phthalocyanine-based material, a phthalocyanine-based material having a phenoxy group is preferable. Specifically, a phthalocyanine derivative having a phenoxy group, such as PhO-VOPc, is preferable. The phthalocyanine derivative having a phenoxy group is soluble in a solvent, and thus has a merit of easy handling for formation of a light-emitting element. In addition, the phthalocyanine derivative having a phenoxy group, which is soluble in a solvent, also has a merit of easy maintenance of an apparatus for forming a film thereof.
The electron-relay layer 707 may contain a donor substance. As examples of the donor substance, materials similar to the donor materials for the electron-injection buffer layer 706 can be given. The donor substance contained in the electron-relay layer 707 facilitates electron transfer, enabling the drive voltage of the light-emitting element to be decreased.
In the case where the donor substance is contained in the electron-relay layer 707, as for the substance having a high electron-transport property, a substance having a LUMO level higher than the acceptor level of the acceptor substance contained in the composite material layer 708 can be used as well as the materials described above. As for the specific energy level, the LUMO level is preferably greater than or equal to −5.0 eV, more preferably greater than or equal to −5.0 eV and less than or equal to −3.0 eV. As examples of such a material, a perylene derivative such as 3,4,9,10-perylenetetracarboxylic dianhydride (abbreviation: PTCDA), a nitrogen-containing condensed aromatic compound such as pirazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile (abbreviation: PPDN), and the like can be given. The nitrogen-containing condensed aromatic compound is preferable for the electron-relay layer 707 because of its stability.
Through the above, the EL layer of this embodiment can be formed.
This embodiment can be combined with any other embodiment as appropriate.
Embodiment 6
In this embodiment, using FIGS. 7A to 7E, FIG. 8, and FIGS. 9A to 9C, description is given of examples of a variety of electronic devices and lighting devices to each of which a light-emitting device of one embodiment of the present invention can be applied.
In the light-emitting device of one embodiment of the present invention, the adhesion between the substrate and the glass layer in a corner portion of the light-emitting device is high; therefore, if force is concentrated on the corner portion of the light-emitting device, the pair of attached substrates is less likely to be detached from each other. Thus, highly reliable electronic device and highly reliable lighting device can be achieved by application of the light-emitting device of one embodiment of the present invention.
Examples of the electronic devices to which the light-emitting device is applied are television devices (also referred to as TV or television receivers), monitors for computers and the like, cameras such as digital cameras and digital video cameras, digital photo frames, mobile phones (also referred to as portable telephone devices), portable game machines, portable information terminals, audio playback devices, large game machines such as pin-ball machines, and the like. Specific examples of these electronic devices and the lighting device are illustrated in FIGS. 7A to 7E, FIG. 8, and FIGS. 9A to 9C.
FIG. 7A illustrates an example of a television device. In a television device 7100, a display portion 7103 is incorporated in a housing 7101. Images can be displayed on the display portion 7103 to which the light-emitting device of one embodiment of the present invention can be applied. Application of the light-emitting device of one embodiment of the present invention to the display portion 7103 enables achievement of a highly reliable television device. In FIG. 7A, the housing 7101 is supported by a stand 7105.
The television device 7100 can be operated by an operation switch of the housing 7101 or a separate remote controller 7110. With operation keys 7109 of the remote controller 7110, channels and volume can be controlled to control images displayed on the display portion 7103. The remote controller 7110 may be provided with a display portion 7107 on which data output from the remote controller 7110 is displayed.
The television device 7100 is provided with a receiver, a modem, or the like. With the receiver, a general television broadcast can be received. Furthermore, the television device 7100 can be connected to a communication network by wired or wireless connection via the modern, which enables one-way (from a transmitter to a receiver) or two-way (between a transmitter and a receiver, between receivers, or the like) data communication.
FIG. 7B illustrates a computer, which includes a main body 7201, a bezel 7202, a display portion 7203, a keyboard 7204, an external connection port 7205, a pointing device 7206, and the like. The light-emitting device of one embodiment of the present invention is applied to the display portion 7203 in this computer. Application of the light-emitting device of one embodiment of the present invention to the display portion 7203 enables achievement of a highly reliable computer.
FIG. 7C illustrates a portable game machine, which includes two housings, a housing 7301 and a housing 7302, which are connected with a joint portion 7303 so that the portable game machine can be opened and folded. A display portion 7304 is incorporated in the housing 7301 and a display portion 7305 is incorporated in the housing 7302. In addition, the portable game machine illustrated in FIG. 7C has a speaker portion 7306, a recording medium insertion portion 7307, an LED lamp 7308, an input means (an operation key 7309, a connection terminal 7310, a sensor 7311 (a sensor of measuring force, displacement, position, speed, acceleration, angular velocity, rotational frequency, distance, light, liquid, magnetism, temperature, chemical substance, sound, time, hardness, electric field, current, voltage, electric power, radiation, flow rate, humidity, gradient, oscillation, odor, or infrared rays), and a microphone 7312), and the like. Needless to say, the structure of the portable game machine is not limited to the above as long as the light-emitting device of one embodiment of the present invention is used for at least either one or both of the display portion 7304 and the display portion 7305, and can have any other accessory as appropriate. Application of the light-emitting device of one embodiment of the present invention to the display portion 7304 and/or the display portion 7305 enables achievement of a highly reliable portable game machine. The portable game machine illustrated in FIG. 7C has a function of reading out a program or data stored in a storage medium to display it on the display portion, or a function of sharing information with another portable game machine by wireless communication. The portable game machine illustrated in FIG. 7C can have a variety of functions without limitation to the above.
FIG. 7D illustrates an example of a mobile phone. A mobile phone 7400 has a display portion 7402 incorporated in a housing 7401, operation buttons 7403, an external connection port 7404, a speaker 7405, a microphone 7406, and the like. The light-emitting device of one embodiment of the present invention is applied to the display portion 7402 in the mobile phone 7400. Application of the light-emitting device of one embodiment of the present invention to the display portion 7402 enables achievement of a highly reliable mobile phone.
Through a touch on the display portion 7402 of the mobile phone 7400 illustrated in FIG. 7D with a finger or the like, data can be input into the mobile phone 7400. Further, operations such as making a call and creating e-mail can be performed by a touch on the display portion 7402 with a finger or the like.
There are mainly three screen modes of the display portion 7402. The first mode is a display mode mainly for displaying images. The second mode is an input mode mainly for inputting data such as text. The third mode is a display-and-input mode in which two modes of the display mode and the input mode are combined.
For example, in the case of making a call or creating an e-mail, the text input mode mainly for inputting text is selected for the display portion 7402 so that text displayed on its screen can be input. In this case, it is preferable to display a keyboard or number buttons on almost the entire screen of the display portion 7402.
Further, a detection device including a sensor for detecting inclination, such as a gyroscope or an acceleration sensor, is provided inside the mobile phone 7400, with which display on the screen of the display portion 7402 can be automatically changed in response to the determined orientation of the mobile phone 7400 (whether the mobile phone is placed horizontally or vertically for a landscape mode or a portrait mode).
The screen mode is switched by touching the display portion 7402 or operating the operation button 7403 of the housing 7401. The screen mode can also be switched depending on the kind of image displayed on the display portion 7402. For example, when the signal of an image displayed on the display portion is a signal of moving image data, the screen mode is switched to the display mode, whereas when the signal is a signal of text data, the screen mode is switched to the input mode.
Moreover, in the input mode, a signal detected by an optical sensor in the display portion 7402 can be detected, whereby the screen mode may be controlled so as to be switched from the input mode to the display mode in the case where input by touching the display portion 7402 is not performed for a specified period.
The display portion 7402 may function as an image sensor. For example, an image of a palm print, a fingerprint, or the like is taken by touch on the display portion 7402 with the palm or finger, whereby personal authentication can be performed. Further, by using a backlight or a sensing light source which emits a near-infrared light in the display portion, an image of a finger vein, a palm vein, or the like can be taken.
FIG. 7E illustrates a desk lamp including a lighting portion 7501, a shade 7502, an adjustable arm 7503, a support 7504, a base 7505, and a power supply 7506. The light-emitting device of one embodiment of the present invention is applied to the lighting portion 7501 of the desk lamp. Application of the light-emitting device of one embodiment of the present invention to the lighting portion 7501 enables achievement of a highly reliable desk lamp. The lamp includes a ceiling light, a wall light, and the like in its category.
FIG. 8 illustrates an example in which the light-emitting device of one embodiment of the present invention is applied to an indoor lighting device 811. The area of the light-emitting device of one embodiment of the present invention can be scaled up, which enables application to a large-area lighting device. Furthermore, the light-emitting device can be used as a roll-type lighting device 812. As illustrated in FIG. 8, a desk lamp 813, which is described in FIG. 7E, may also be used in a room provided with the interior lighting device 811.
FIGS. 9A and 9B illustrate a foldable tablet terminal. In FIG. 9A, the tablet terminal is opened, and includes a housing 9630, a display portion 9631a, a display portion 9631b, a display-mode switching button 9034, a power button 9035, a power-saving-mode switching button 9036, a clip 9033, and an operation button 9038.
Part of the display portion 9631a can form a touch panel region 9632a, in which data can be input by touching operation keys 9037 which are displayed. Although a structure in which a half region in the display portion 9631a has only a display function and the other half region has a touch panel function is shown as an example in FIG. 9A, the display portion 9631a is not limited to this structure. The entire area of the display portion 9631a may have a touch panel function. For example, keyboard buttons are displayed on the entire screen of the display portion 9631a such that the entire screen of the display portion 9631a functions as a touch panel, whereas the display portion 9631b can be used as a display screen.
Like the display portion 9631a, part of the display portion 9631b can form a touch panel region 9632b. Further, a switching button 9639 for showing/hiding a keyboard of the touch panel can be touched with a finger, a stylus, or the like, so that keyboard buttons can be displayed on the display portion 9631b. 
Touch input can be performed concurrently on the touch panel regions 9632a and 9632b. 
The display-mode switching button 9034 can switch the display orientation (e.g., between landscape mode and portrait mode) and select a display mode (switch between monochrome display and color display), for example. With the power-saving-mode switching button 9036, the luminance of display can be optimized in accordance with the amount of external light when the tablet is in use, which is detected with an optical sensor incorporated in the tablet. The tablet may include any another detection device such as a sensor for detecting orientation (e.g., a gyroscope or an acceleration sensor) as well as the optical sensor.
FIG. 9A illustrates an example in which the display portion 9631a and the display portion 9631b have the same display area; however, without limitation thereon, one of the display portions may be different from the other display portion in size or display quality. For example, one of them may be a display panel that can display higher-definition images than the other.
In FIG. 9B, the tablet terminal is folded, which includes the housing 9630, a solar battery 9633, a charge and discharge control circuit 9634, a battery 9635, and a DCDC converter 9636. FIG. 9B illustrates an example in which the charge and discharge control circuit 9634 includes the battery 9635 and the DCDC converter 9636.
Since the tablet terminal can be folded in two, the housing 9630 can be closed when the tablet is not in use. Thus, the display portions 9631a and 9631b can be protected, thereby providing a tablet terminal with high endurance and high reliability for long-term use.
In addition, the tablet terminal illustrated in FIGS. 9A and 9B can have a function of displaying a variety of data (e.g., a still image, a moving image, and a text image), a function of displaying a calendar, a date, the time, or the like on the display portion, a touch-input function of operating or editing the data displayed on the display portion by touch input, a function of controlling processing by a variety of software (programs), and the like.
The solar battery 9633, which is attached on the surface of the tablet terminal, supplies electric power to a touch panel, a display portion, an image signal processor, and the like. The solar cell 9633 is preferably provided on one or two surfaces of the housing 9630, because the battery 9635 can be charged efficiently. A lithium ion battery can be used as the battery 9635, which has a merit in reduction in size or the like.
The structure and the operation of the charge and discharge control circuit 9634 illustrated in FIG. 9B are described using a block diagram in FIG. 9C. FIG. 9C illustrates the solar battery 9633, the battery 9635, the DCDC converter 9636, a converter 9637, switches SW1 to SW3, and the display portion 9631. The battery 9635, the DCDC converter 9636, the converter 9637, and the switches SW1 to SW3 are included in the charge and discharge control circuit 9634 in FIG. 9B.
First, an example of operation in the case where power is generated by the solar battery 9633 using external light is described. The voltage of power generated by the solar battery is raised or lowered by the DCDC converter 9636 to a voltage for charging the battery 9635. Then, when the power from the solar battery 9633 is used for the operation of the display portion 9631, the switch SW1 is turned on and the voltage of the power is raised or lowered by the converter 9637 to a voltage needed for the display portion 9631. On the other hand, when display on the display portion 9631 is not performed, the switch SW1 is turned off and the switch SW2 is turned on so that the battery 9635 is charged.
In this embodiment, the solar battery 9633 is described as an example of a power generation means; however, there is no particular limitation on a way of charging the battery 9635, and the battery 9635 may be charged with another power generation means such as a piezoelectric element or a thermoelectric conversion element (Peltier element). For example, the battery 9635 may be charged with a non-contact power transmission module which is capable of charging by transmitting and receiving power by wireless (without contact), or another charging means may be used in combination.
As described above, electronic devices and lighting devices can be obtained by application of the light-emitting device of one embodiment of the present invention. The applicable range of the light-emitting device of one embodiment of the present invention is so wide that the light-emitting device can be applied to electronic devices in any field.
The structure described in this embodiment can be combined with any structure described in any of the above embodiments as appropriate.
Example 1
In this example, a sealed structure of one embodiment of the present invention is described using FIGS. 10A to 10C, FIGS. 11A and 11B, and FIGS. 12A and 12B.
First, a method for manufacturing a sealed structure of this example is described using FIGS. 10A to 10C. In each of FIGS. 10A to 10C, a plan view and a cross-sectional view taken along dashed-dotted line G-H in the plan view are shown. A glass substrate 209 is omitted in the plan views of FIGS. 10B and 10C.
As shown in FIG. 10A, frit paste 203 was applied over a glass substrate 201 by screen printing. A glass paste containing bismuth oxide or the like was used as the frit paste 203.
Then, drying was performed thereon at 140° C. for 20 minutes.
Images of the frit paste 203 applied over the glass substrate 201, with an optical microscope are shown in FIGS. 11A and 11B. FIG. 11A is the image of a region surrounded by a dotted line 211 in FIG. 10A, and FIG. 11B is the image of a region surrounded by a dotted line 213 in FIG. 10A. As seen from FIGS. 11A and 11B, the width of a corner portion of the frit paste 203 is larger than that of a side portion of the frit paste 203. Further, in the corner portion, the radius of the outer contour is smaller than that of the inner contour.
Next, pre-baking was performed thereon to remove an organic solvent or a resin in the frit paste 203. In this manner, a glass layer 204 was formed. As the pre-baking, drying was performed at 450° C. for 60 minutes.
Then, the glass substrate 201 and the glass substrate 209 were disposed to face each other to make the glass layer 204 and the glass substrate 209 in close contact with each other, and the glass layer 204 was irradiated with laser light 207 from the glass substrate 201 side (see FIG. 10B). The laser light irradiation was performed under the following conditions: a semiconductor laser with a wavelength of 940 nm was used, the output power was 28 W, and the scanning speed was 1 mm/sec. The beam diameter of the laser beam 207 was greater than the width of a corner portion of the glass layer 204.
Through the above, the sealed structure of this example in which the glass substrate 201 is attached to the glass substrate 209 with a glass layer 205 was manufactured (FIG. 10C).
Images of a welded region between the glass layer 205 and the glass substrate 209 of the sealed structure of this example, with an optical microscope are shown in FIGS. 12A and 12B. Specifically, the welded region was observed in a direction denoted by an arrow 215 in FIG. 10C.
FIG. 12A shows a part of the welded region surrounded by a dotted line 217 in FIG. 10C, and FIG. 12B is a part of the welded region surrounded by a dotted line 219 in FIG. 10C.
As seen from FIGS. 11A and 11B and FIGS. 12A and 12B, a difference between the shape of the frit paste 203 (FIGS. 11A and 11B) and the shape of the glass layer 205 (FIGS. 12A and 12B) is small. That is, it is found that a change of shape of the glass layer 205 between before and after the attachment is small. Therefore, a sealed structure can be manufactured at a yield higher than that in the case where a resin is used.
As shown in FIGS. 12A and 12B, the width of a corner portion of the welded region between the glass layer 205 and the glass substrate 209 is larger than that of a side portion of the welded region. Further, in the corner portion, the radius of the outer contour is smaller than that of the inner contour.
The area of the welded region between the glass layer and the substrate in a corner portion of the sealed structure manufactured in this example is large. Accordingly, according to one embodiment of the present invention, the sealed structure with high adhesion between the glass layer and the substrate in its corner portion can be provided.
This application is based on Japanese Patent Application serial no. 2011-260216 filed with Japan Patent Office on Nov. 29, 2011, the entire contents of which are hereby incorporated by reference.

## Claims

1. A sealed structure comprising:
a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate; and
a glass layer interposed between the first substrate and the second substrate, defining a sealed space between the first substrate and the second substrate, and provided along a periphery of the first surface of the first substrate so as to form a closed loop,
wherein the glass layer comprises a welded region,
wherein the welded region includes a corner portion, and
wherein a radius of an outer contour of the corner portion of the welded region is smaller than or equal to a radius of an inner contour of the corner portion of the welded region.

2. The sealed structure according to claim 1, wherein at least one of the first substrate and the second substrate comprises a film formed over the first surface thereof.

3. The sealed structure according to claim 1, further comprising in the sealed space:
a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes.

4. The sealed structure according to claim 1,
wherein the radius of the outer contour of the corner portion is in the order of 100 μm.

5. The sealed structure according to claim 1,
wherein the radius of the outer contour of the corner portion is greater than 0 and smaller than or equal to 100 μm.

6. A sealed structure comprising:
a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate and an area of the first surface of the first substrate being smaller than or equal to an area of the first surface of the second substrate; and
a glass layer interposed between the first substrate and the second substrate, defining a sealed space between the first substrate and the second substrate, and provided along a periphery of the first surface of the first substrate so as to form a closed loop,
wherein the glass layer comprises a welded region,
wherein the welded region includes a corner portion, and
wherein a radius of an outer contour of the corner portion of the welded region is smaller than or equal to a radius of an inner contour of the corner portion of the welded region.

7. The sealed structure according to claim 6, wherein at least one of the first substrate and the second substrate comprises a film formed over the first surface thereof.

8. The sealed structure according to claim 6, further comprising in the sealed space:
a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes.

9. The sealed structure according to claim 6,
wherein the radius of the outer contour of the corner portion is in the order of 100 μm.

10. The sealed structure according to claim 6,
wherein the radius of the outer contour of the corner portion is greater than 0 and smaller than or equal to 100 μm.

11. A sealed structure comprising:
a first substrate and a second substrate, a first surface of the first substrate facing a first surface of the second substrate, and an area of the first surface of the first substrate being smaller than or equal to an area of the first surface of the second substrate; and
a glass layer interposed between the first substrate and the second substrate, defining a sealed space between the first substrate and the second substrate, and provided along a periphery of the first surface of the first substrate so as to form a closed loop,
wherein the glass layer comprises a welded region,
wherein the welded region includes a corner portion and a side portion,
wherein a width of the corner portion of the welded region is larger than a width of the side portion of the welded region.

12. The sealed structure according to claim 11, wherein at least one of the first substrate and the second substrate comprises a film formed over the first surface thereof.

13. The sealed structure according to claim 11, further comprising in the sealed space:
a light-emitting element in which a layer containing a light-emitting organic compound is provided between a pair of electrodes.

14. The sealed structure according to claim 11,
wherein a radius of an outer contour of the corner portion is in the order of 100 μm.

15. The sealed structure according to claim 11,
wherein a radius of an outer contour of the corner portion is greater than 0 and smaller than or equal to 100 μm.