JP5250196B2 - Display device and electronic device - Google Patents

Description

  The present invention relates to a display device comprising an anode, a cathode, and an element having a structure in which a thin film emitting light by electroluminescence (hereinafter referred to as “EL”) is sandwiched between the anode and the cathode on a substrate. About.

An EL element is an element that emits light by forming a thin film or a crystal containing an organic compound or an inorganic compound between a cathode and an anode and energizing between the anode and the anode. In recent years, development of an EL element in which a thin film containing an organic compound as a main component is disposed between a cathode and an anode, that is, an organic EL element has been actively performed.

The organic EL element is expected to be applied in various fields, and is considered to be used from a simple lighting device to a display used in a mobile phone or a personal computer. Organic EL elements are manufactured by sandwiching a material that emits light when energized between a pair of electrodes. Unlike liquid crystals, the EL elements themselves emit light, so there is no need for a light source such as a backlight, and the element itself is very thin and thin. This is very advantageous for making lightweight displays.

As such a display, for example, a display device having an organic EL element using a highly reflective metal for a cathode and a transparent electrode for an anode on a substrate has been proposed. By using a highly reflective metal for the cathode, it is possible to improve the luminance of light emitted from the light emitting layer, but on the other hand, external light is reflected on the metal surface, and an external image is reflected, and the display image is displayed from the observer. The display characteristics of the image are degraded, such as making the display difficult to see and reducing the brightness of the display image. In order to solve this problem, a method of suppressing reflection of an external image by providing an antireflection means has been proposed. For example, a display device (Patent Document 1) provided with an antireflection means consisting of a ¼ wavelength plate, a reflective polarizing plate, and an absorbing polarizing plate, or a reflection consisting of a wavelength correction plate, a planar linearly polarized beam splitter, and a polarizing plate. A display device (Patent Document 2) provided with prevention means is disclosed.
JP 2005-1000078 A JP-A-11-45058

However, a display device provided with an antireflection means consisting of a quarter-wave plate, a reflective polarizing plate, and an absorption polarizing plate, and an antireflection means consisting of a wavelength correction plate, a planar linearly polarized beam splitter, and a polarizing plate are provided. In the display device, not only can the external image reflection due to the reflection of the external light on the cathode surface not be suppressed efficiently, but also a part of the external light incident on the display device becomes a reflective polarizing plate or a planar linear polarization beam splitter. There is a possibility that the external image is not completely eliminated due to reflection on the surface without passing through.

It is an object of the present invention to propose a display device that prevents reflection of external light from a reflective polarizing plate and improves light extraction efficiency from a light emitting layer.

  The display device of the present invention includes a light emitting layer provided on a reflective electrode, a transparent electrode provided on the light emitting layer, a reflective polarizing plate provided on the transparent electrode, and a reflective polarizing plate. It has the quarter wavelength plate provided and the polarizing plate provided on the said quarter wavelength plate, It is characterized by the above-mentioned.

  The display device of the present invention has a transparent electrode, a light emitting layer, and a reflective electrode on one surface of a substrate, and a reflective polarizing plate, a quarter-wave plate, and a polarized light on the other surface of the substrate. The quarter wavelength plate is provided between the reflective polarizing plate and the polarizing plate.

  The display device of the present invention has a transparent electrode, a light emitting layer, and a reflective electrode on one surface of a transparent substrate, a reflective polarizing plate on the other surface of the transparent substrate, and 1 in the range of visible light. / 4 wavelength plate having an effect as a ¼ wavelength plate, and a polarizing plate, and the broadband ¼ wavelength plate is provided between the reflective polarizing plate and the polarizing plate. It is characterized by being.

  The display device of the present invention includes a light emitting layer provided on a reflective electrode, a transparent electrode provided on the light emitting layer, a substrate provided on the transparent electrode, and a reflective provided on the substrate. It has a polarizing plate, a quarter wavelength plate provided on the reflective polarizing plate, and a polarizing plate provided on the quarter wavelength plate.

  The display device of the present invention includes a reflective electrode provided on a substrate, a light emitting layer provided on the reflective electrode, a transparent electrode provided on the light emitting layer, and the transparent electrode. A reflective polarizer, a quarter-wave plate provided on the reflective polarizer, and a polarizer provided on the quarter-wave plate.

  The display device of the present invention includes a first quarter-wave plate provided on a first polarizing plate, a first reflective polarizing plate provided on the first quarter-wave plate, A substrate provided on the first reflective polarizing plate, a first transparent electrode provided on the substrate, a light emitting layer provided on the first transparent electrode, and provided on the light emitting layer A second transparent electrode, a second reflective polarizing plate provided on the second transparent electrode, a second quarter-wave plate provided on the second reflective polarizing plate, And a second polarizing plate provided on the second quarter-wave plate.

  The display device of the present invention includes a quarter wavelength plate provided on a polarizing plate, a reflective polarizing plate provided on the quarter wavelength plate, a substrate provided on the reflective polarizing plate, and a substrate. A thin film transistor having a semiconductor film having a source region or a drain region provided, an interlayer insulating film having a contact hole reaching the source region or the drain region provided on the thin film transistor, and provided on the interlayer insulating film A wiring electrically connected to the source region or the drain region, a transparent electrode provided on the interlayer insulating film and the wiring, a light emitting layer provided on the transparent electrode, and the light emitting layer And a reflective electrode provided on the substrate.

  The display device of the present invention includes a thin film transistor having a semiconductor film having a source region or a drain region provided on a substrate, and an interlayer insulation having a contact hole provided on the thin film transistor and reaching the source region or the drain region. A film, a wiring electrically connected to the source region or the drain region provided on the interlayer insulating film, a reflective electrode provided on the interlayer insulating film and the wiring, and the reflective electrode A light emitting layer provided on the light emitting layer, a transparent electrode provided on the light emitting layer, a reflective polarizing plate provided on the transparent electrode, a quarter-wave plate provided on the reflective polarizing plate, And a polarizing plate provided on a quarter-wave plate.

  The display device of the present invention includes a first quarter-wave plate provided on a first polarizing plate, a first reflective polarizing plate provided on the first quarter-wave plate, A substrate provided on the first reflective polarizing plate, a thin film transistor having a semiconductor film having a source region or a drain region provided on the substrate, and the source region or drain region provided on the thin film transistor An interlayer insulating film having a contact hole reaching the first insulating layer; a wiring electrically connected to the source region or the drain region provided on the interlayer insulating film; and a first provided on the interlayer insulating film and the wiring. Transparent electrode, a light emitting layer provided on the first transparent electrode, a second transparent electrode provided on the light emitting layer, and a second reflection provided on the second transparent electrode Polarizing plate and the second reflection And having a second quarter wave plate provided on the optical plate and a second polarizing plate provided on the second quarter-wave plate.

  The display device of the present invention is characterized in that a prism is formed between the substrate and the reflective polarizing plate.

  The display device of the present invention has a transparent electrode, a light emitting layer, and a reflective electrode on one surface of a substrate, and a first quarter-wave plate and a reflective polarizing plate on the other surface of the substrate. And a second quarter-wave plate and a polarizing plate.

  A display device of the present invention includes a light emitting layer provided on a reflective electrode, a transparent electrode provided on the light emitting layer, a substrate provided on the transparent electrode, and a first electrode provided on the substrate. 1 quarter-wave plate, a reflective polarizer provided on the first quarter-wave plate, a second quarter-wave plate provided on the reflective polarizer, and the second And a polarizing plate provided on a quarter-wave plate.

  The display device of the present invention includes a second quarter-wave plate provided on a polarizing plate, a reflective polarizing plate provided on the second quarter-wave plate, and provided on the reflective polarizing plate. A thin film transistor having a semiconductor film having a source region or a drain region provided on the substrate, and a substrate provided on the first quarter wavelength plate, An interlayer insulating film having a contact hole reaching the source region or the drain region provided on the thin film transistor; and a wiring electrically connected to the source region or the drain region provided on the interlayer insulating film; It has a transparent electrode provided on the interlayer insulating film and the wiring, a light emitting layer provided on the transparent electrode, and a reflective electrode provided on the light emitting layer.

  The display device of the present invention is characterized in that a prism is formed between the substrate and the first quarter-wave plate.

  In the display device of the present invention, the quarter-wave plate, the first quarter-wave plate, or the second quarter-wave plate is a broadband quarter-wave plate. .

  The electronic device of the present invention includes the display device.

In the present invention, reflection of external video due to reflection of external light on the reflective polarizing plate can be suppressed, and image display characteristics can be improved. In addition, light emitted from the light emitting layer can be efficiently extracted, and a reduction in brightness of the display image can be suppressed.

  The best mode for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following forms, and those skilled in the art can easily understand that the forms and details can be variously changed 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 of the embodiments below. Note that in structures of the present invention described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings, and description thereof is not repeated. Further, Embodiments 1 to 7 below can be used in any combination.

Note that in this specification, an axis that transmits light among polarization axes of the polarizing plate or the reflective polarizing plate is referred to as a transmission axis. Moreover, the axis | shaft which absorbs light among the polarization axes of a polarizing plate is called an absorption axis. Note that the transmission axis and the absorption axis are orthogonal to each other. Such an absorption polarizing plate having an absorption axis is simply referred to as a polarizing plate. A polarizing plate having a function of transmitting light of a specific polarization component and reflecting light of another polarization component is called a reflection polarizing plate.

Here, a linearly polarized light reflective polarizing plate or a circularly polarized light reflective polarizing plate can be used as the reflective polarizing plate. In this specification, a linearly polarized light reflecting polarizing plate transmits one polarized light component of linearly polarized light and reflects another polarized light component (that is, any one of linearly polarized light such as P wave or S wave, Component, for example, having a property of transmitting a P wave component and reflecting an S wave component), and a circularly polarized light-reflecting polarizing plate is a rotation direction of one of circularly polarized light having a clockwise or counterclockwise rotation direction. The thing which has a property which lets a component pass and reflects the other is pointed out. As the linearly polarized light reflective polarizing plate, for example, a multilayer film in which transparent layers having different refractive indexes are laminated can be used. Further, as the circularly polarized light polarizing plate, for example, a material made of a substance having a cholesteric layer can be used.

  In this specification, a combination of a half-wave plate and a quarter-wave plate may be used instead of the quarter-wave plate. In this specification, the term “quarter wave plate” is used to include a broadband quarter wave plate that has an effect as a quarter wave plate in the visible light range (preferably 380 nm to 780 nm).

(Embodiment 1)
In this embodiment mode, a display device including a reflective polarizing plate, a quarter-wave plate, and a polarizing plate will be described. FIG. 1 illustrates part of a display device in this embodiment. This configuration is effective not only for organic EL and inorganic EL, but also for displays such as PDP, SED, and FED.

  As shown in FIG. 1, the display device in the present embodiment has a transparent electrode 11, a light emitting layer 12, and a reflective electrode 13 stacked on a substrate 100, and is on a substrate 100 opposite to the surface on which the transparent electrode 11 is formed. A reflective polarizing plate 14, a quarter wavelength plate 15, and a polarizing plate 16 are laminated. That is, the reflective electrode 13, the light emitting layer 12, the transparent electrode 11, the substrate 100, the reflective polarizing plate 14, the quarter wavelength plate 15, and the polarizing plate 16 are sequentially stacked. In the present embodiment, light emitted from the light emitting layer 12 is extracted from the transparent electrode 11 side (substrate 100 side), and light emission can be obtained by passing a current between the transparent electrode 11 and the reflective electrode 13. it can.

The polarizing plate 16 has a function of transmitting a linearly polarized light component having a vibration surface parallel to the transmission axis and absorbing a linearly polarized light component having a vibration surface orthogonal to the transmission axis.

In the present embodiment, when a linearly polarized reflective polarizer is used as the reflective polarizer, the transmission axis of the reflective polarizer 14 and the slow axis of the quarter wave plate 15 form an angle of 45 ° or 135 °. Deploy. When a linear reflection polarizing plate is used, the transmission axis of the reflection polarizing plate 14 and the transmission axis of the polarizing plate 16 are arranged in parallel.

In the present embodiment, since the light emitted from the light emitting layer 12 is extracted through the substrate 100, the substrate 100 needs to be a transparent substrate. As the substrate 100, for example, a glass substrate, a quartz substrate, a flexible substrate, or the like can be used. The flexible substrate is a substrate that can be bent (flexible), and examples thereof include a plastic substrate made of polyimide, acrylic, polyethylene terephthalate, polycarbonate, polyarylate, polyethersulfone, or the like. A thin film-like substrate made of polypropylene, polyester, vinyl, polyvinyl fluoride, vinyl chloride, or the like can also be used. These substrates may be coated with a planarizing film, a nitride film, an oxide film, or a laminated film thereof, if necessary, or may be used after being polished by CMP or the like. good.

As the transparent electrode 11, indium tin oxide (ITO, Indium Tin Oxide), indium tin oxide containing silicon oxide (ITSO), zinc oxide (ZnO), indium oxide containing silicon oxide, and further 2 to 20 wt% Indium zinc oxide (IZO), zinc oxide containing gallium (GZO), tin oxide (SnO ₂ ), indium oxide (IZO) formed using a target in which zinc oxide (ZnO) is mixed. In ₂ O ₃ ) or the like can be used.

The light-emitting layer 12 is a layer containing a light-emitting substance, and has a configuration in which, for example, a hole transport layer, a light-emitting layer, and an electron transport layer are sequentially stacked on the transparent electrode 11. The structure of the light emitting layer 12 is not limited to this structure, and it is sufficient if it has at least a light emitting layer. For example, in addition to the light emitting layer, functional layers such as an electron injection layer, an electron transport layer, a hole blocking layer, a hole transport layer, and a hole injection layer may be freely combined. In the present embodiment, since the transparent electrode 11 functions as an anode, a hole injection layer, a hole transport layer, a hole blocking layer, a light emitting layer, an electron transport layer, and an electron injection layer are laminated in this order from the transparent electrode 11 side. Moreover, you may form the mixed layer or mixed junction which combined these each layer. Note that the boundaries between the layers are not necessarily clear, and there are cases where the materials constituting the layers are partially mixed and the interface is unclear. For each layer, an organic material or an inorganic material can be used. As the organic material, any of a high molecular weight material, a medium molecular weight material, and a low molecular weight material can be used. The medium molecular weight material corresponds to a low polymer having a number of repeating structural units (degree of polymerization) of about 2 to 20.

As the reflective electrode 13, it is preferable to use a metal having a high reflectance (for example, a metal having a reflectance of 40% or more). For example, aluminum (Al), silver (Ag), or an AlLi alloy, an MgAg alloy, or the like that includes these can be used. The reflective electrode 13 may have a laminated structure of a highly reflective metal and another electrode material. By forming a thin film (for example, about 5 nm) of an alkali metal or an alkaline earth metal and laminating it with a metal having a high reflectivity, it is possible to improve the electron injecting property.

Here, the case where the reflective polarizing plate 14 is a linearly polarizing reflective polarizing plate will be described. First, light components (referred to as first polarized light) parallel to the absorption axis of the polarizing plate 16 out of the external light incident from the observation surface of the display device, that is, the front side of the polarizing plate 16 are absorbed by the polarizing plate 16 and are displayed. The second polarized light parallel to the transmission axis of the polarizing plate 16 is incident on. This second polarized light passes through the quarter-wave plate 15 and is converted into clockwise or counterclockwise circularly polarized light. In this embodiment, a case where the light is converted to clockwise circularly polarized light is considered. Of the second polarized light converted to clockwise circularly polarized light, the polarized light component that does not coincide with the transmission axis of the reflective polarizing plate 14 is reflected by the reflective polarizing plate 14 and returns to the quarter wavelength plate 15 as counterclockwise circularly polarized light. The counterclockwise circularly polarized light passes through the quarter-wave plate 15 and is converted into third polarized light having a polarization axis perpendicular to the polarization axis of the second polarization. That is, the third polarized light has a polarization axis parallel to the absorption axis of the polarizing plate 16. Similarly, in the case of counterclockwise circularly polarized light, third polarized light having a polarization axis parallel to the absorption axis of the polarizing plate 16 is emitted. Therefore, the third polarized light is absorbed without passing through the polarizing plate 16.

In addition, a polarized light component that coincides with the transmission axis of the reflective polarizing plate 14 in the second polarized light passes through the reflective polarizing plate 14. Then, after being reflected on the reflective electrode 13 and again passing through the reflective polarizing plate 14, the fourth polarized light having a polarization component perpendicular to the polarization axis of the second polarized light is passed through the quarter-wave plate 15. Converted. Since the fourth polarized light coincides with the absorption axis of the polarizing plate 16, it is absorbed without passing through the polarizing plate 16. Accordingly, the component of the external light incident on the display device is absorbed by the polarizing plate 16, and the external light is not emitted to the outside again, and reflection of an external image can be suppressed.

On the other hand, the light emitted from the light-emitting layer 12 passes through the reflective polarizing plate 14 as it is and the polarization component parallel to the transmission axis of the reflective polarizing plate 14 becomes circularly polarized light through the quarter-wave plate 15 and has the same component as the transmission axis. Light passes through the polarizing plate 16 and is emitted from the display device. The remaining polarization component is reflected by the reflective polarizing plate 14 and returns toward the light emitting layer 12, is reflected by the reflective electrode 13, and enters the reflective polarizing plate 14 again. Here, light having a polarization axis that is not parallel to the polarization axis of the reflective polarizer 14 is repeatedly reflected between the reflective polarizer 14 and the reflective electrode 13. Then, by being repeatedly reflected, the polarization axis is shifted, the polarization axis of the light that has been repeatedly reflected becomes parallel to the polarization axis of the reflective polarizing plate 14, and the reflective polarizing plate 14, the quarter wavelength plate 15, the polarizing plate 16 is ejected from the display device. For this reason, it becomes possible to effectively utilize the light-emitting components that could not be used conventionally, and the brightness of the display image can be improved.

Further, a polarizing plate 17 may be additionally provided between the reflective polarizing plate 14 and the quarter wavelength plate 15 (FIG. 1B). In that case, it arrange | positions so that the transmission axis of the polarizing plate 16 and the polarizing plate 17 may correspond. By providing the polarizing plate 17, the second polarized light converted to the clockwise circularly polarized light does not coincide with the transmission axis of the reflective polarizing plate 14, and the polarized light reflected by the reflective polarizing plate 14 is reflected in the polarizing plate 17. Since the light is absorbed, the external light is not emitted to the outside again, and reflection of an external image can be more effectively suppressed.

The case where the reflective polarizing plate 14 is a circularly polarizing reflective polarizing plate will be described. First, light components (referred to as first polarized light) parallel to the absorption axis of the polarizing plate 16 out of the external light incident from the observation surface of the display device, that is, the front side of the polarizing plate 16 are absorbed by the polarizing plate 16 and are displayed. The second polarized light parallel to the transmission axis of the polarizing plate 16 is incident on. This second polarized light passes through the quarter-wave plate 15 and is converted into clockwise or counterclockwise circularly polarized light. In this embodiment, a case where the light is converted to clockwise circularly polarized light is considered. Here, the reflective polarizing plate 14 has a function of transmitting the counterclockwise circularly polarized light component and reflecting the clockwise circularly polarized light component. The second polarized light converted to the clockwise circularly polarized light is reflected by the reflective polarizing plate 14, returns to the quarter wavelength plate 15, and passes through the quarter wavelength plate 15, whereby the polarization axis of the second polarized light is obtained. Is converted into a third polarized light having a polarization axis perpendicular thereto. That is, the third polarized light has a polarization axis parallel to the absorption axis of the polarizing plate 16. Here, when the second polarized light is converted into the counterclockwise circularly polarized light by the quarter wavelength plate 15, it has a function of transmitting the clockwise circularly polarized light to the reflective polarizing plate 14 and reflecting the counterclockwise circularly polarized light. Is converted into third polarized light having a polarization axis parallel to the absorption axis of the polarizing plate 16. Accordingly, the component of the external light incident on the display device is absorbed by the polarizing plate 16, and the external light is not emitted to the outside again, and reflection of an external image can be suppressed.

On the other hand, the light emitted from the light-emitting layer 12 passes through the reflective polarizing plate 14, the quarter-wave plate 15, and the polarizing plate 16 as it is, and the circularly polarized light component that does not coincide with the rotational direction of the spiral of the cholesteric layer of the reflective polarizing plate is displayed. Injected from the device. In addition, the circularly polarized light component that coincides with the rotational direction of the spiral is reflected by the reflective polarizing plate 14, returns to the light emitting layer 12 direction, is reflected by the reflective electrode 13, and enters the reflective polarizing plate 14 again. Here, the polarized light that does not pass through the reflective polarizing plate 14 is repeatedly reflected between the reflective polarizing plate 14 and the reflective electrode 13. Then, by being repeatedly reflected, the polarization axis is shifted, and the light that has been reflected is transmitted through the reflective polarizing plate 14, passes through the quarter-wave plate 15 and the polarizing plate 16, and is emitted from the display device. For this reason, it becomes possible to effectively utilize the light-emitting components that could not be used conventionally, and the brightness of the display image can be improved.

In the present embodiment, an antireflection film, an antireflection film, or the like may be provided over the polarizing plate 16. An antireflection film suppresses reflection of external light on the surface by laminating thin films having different refractive indexes. By providing the antireflection film, reflection of external light on the surface of the polarizing plate 16 can be suppressed, and reflection of an external image can be further suppressed.

In addition, by using a broadband quarter-wave plate having a function as a quarter-wave plate in the visible light range (preferably 380 nm to 780 nm) as the quarter-wave plate, it is favorable in the visible light range. A quarter wavelength characteristic can be obtained, and not only can external light be canceled in a wide range, but also light emitted from the light emitting layer 12 can be efficiently extracted.

In the display device of the present embodiment, reflection of external video due to reflection of external light on the reflective polarizing plate 14 can be suppressed, and image display characteristics can be improved. Further, the light emitted from the light emitting layer 12 can be extracted efficiently, and the brightness of the display image can be improved.

(Embodiment 2)
In this embodiment, a case where a prism layer is provided between the reflective polarizing plate 14 and the substrate 100 will be described. 2 that are the same as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. FIG. 2 shows part of the display device in this embodiment.

In the display device in this embodiment, a transparent electrode 11, a light emitting layer 12, and a reflective electrode 13 are stacked over a substrate 100 as shown in FIG. A prism layer 201, a reflective polarizing plate 14, a quarter-wave plate 15, and a polarizing plate 16 are laminated on 100. That is, the reflective electrode 13, the light emitting layer 12, the transparent electrode 11, the substrate 100, the prism layer 201, the reflective polarizing plate 14, the ¼ wavelength plate 15, and the polarizing plate 16 are sequentially stacked.

In the present embodiment, the prism layer 201 is provided in order to shift the polarization axis of polarized light, the protrusions are formed in a stripe shape on the surface, and the cross section in the direction perpendicular to the stripe is a comb having a random size. It is a film-like member. In the present embodiment, the prism layer 201 is not particularly limited as long as it is a scattering layer capable of shifting the polarization axis of polarized light. Such a scattering layer may be, for example, a thin film 203 in which substances 202 made of materials having different sizes and refractive indexes are diffused (FIG. 2B). Moreover, you may provide both a scattering layer and a prism layer.

  In the present embodiment, when a linearly polarized reflective polarizer is used as the reflective polarizer, the polarization axis of the reflective polarizer 14 and the slow axis of the quarter wave plate 15 are at an angle of 45 ° or 135 °. Deploy. Further, when a linear reflection polarizing plate is used, the transmission axis of the reflection polarizing plate 14 and the transmission axis of the polarizing plate 16 are arranged in parallel.

With this configuration, as in the first embodiment, external light incident on the display device is absorbed by the polarizing plate 16 and is not emitted to the outside again, and reflection of external images can be suppressed.

  On the other hand, the light emitted from the light emitting layer 12 is efficiently reflected between the reflective polarizing plate 14 and the reflective electrode 13 in the same manner as in the first embodiment, so that the light emitted from the light emitting layer 12 is efficiently reflected. It is possible to emit light, and it is possible to effectively use light-emitting components that could not be used conventionally, and the brightness of the display image can be improved. In the present embodiment, since the reflection is repeatedly performed between the reflective polarizing plate 14 and the reflective electrode 13 via the prism layer 201, the polarization axis can be efficiently shifted, and the light emitting layer 12 emits light. The extraction efficiency of the emitted light can be further improved. Only one prism layer 201 may be provided as long as it has an action of changing the direction and state of polarized light that is repeatedly reflected between the reflective polarizing plate 14 and the reflective electrode 13 as well as condensing the emitted light. A plurality of sheets may be provided.

In the display device of the present embodiment, reflection of external video due to reflection of external light on the reflective polarizing plate 14 can be suppressed, and image display characteristics can be improved. Further, the light emitted from the light emitting layer 12 can be extracted more efficiently, and the brightness of the display image can be improved.

(Embodiment 3)
In the present embodiment, a case where a quarter wavelength plate is provided between the reflective polarizing plate 14 and the substrate 100 will be described. 3 that are the same as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. FIG. 3 illustrates part of the display device in this embodiment.

As shown in FIG. 3, the display device in the present embodiment has a transparent electrode 11, a light emitting layer 12, and a reflective electrode 13 laminated on a substrate 100, and is on a substrate 100 opposite to the surface on which the transparent electrode 11 is formed. A quarter wavelength plate 301 (referred to as a first quarter wavelength plate), a reflective polarizing plate 14, a quarter wavelength plate 15 (referred to as a second quarter wavelength plate), and a polarizing plate 16 are laminated. Yes. That is, the reflective electrode 13, the light emitting layer 12, the transparent electrode 11, the substrate 100, the quarter wavelength plate 301, the reflective polarizing plate 14, the quarter wavelength plate 15, and the polarizing plate 16 are sequentially stacked.

  In this embodiment, when a linearly polarized reflective polarizer is used as the reflective polarizer, the polarization axis of the reflective polarizer 14 and the polarization axis of the first quarter wave plate 301 form an angle of 45 ° or 135 °. Arrange as follows. When a linearly polarized reflective polarizer is used as the reflective polarizer 14, the transmission axis of the reflective polarizer 14 and the transmission axis of the second quarter-wave plate 15 are arranged at an angle of 45 ° or 135 °. To do. When a linearly polarized reflective polarizing plate is used, the transmission axis of the reflective polarizing plate 14 and the transmission axis of the polarizing plate 16 are arranged in parallel.

Here, a case where the reflective polarizing plate is a linearly polarizing reflective polarizing plate will be described. First, of the external light incident from the observation surface of the display device, that is, the front side of the polarizing plate 16, a polarized light component (referred to as first polarized light) parallel to the absorption axis of the polarizing plate 16 is absorbed by the polarizing plate 16. The second polarized light parallel to the transmission axis of the polarizing plate 16 is incident on. This second polarized light is converted into clockwise or counterclockwise circularly polarized light by passing through the second quarter-wave plate 15, and the component of the second polarized light that does not coincide with the transmission axis of the reflective polarizing plate 14 Is reflected by the reflective polarizing plate 14, but is absorbed without passing through the polarizing plate 16 as in the first embodiment, and the component of the external light incident on the display device is not emitted to the outside again.

In addition, a polarized light component that coincides with the transmission axis of the reflective polarizing plate 14 in the second polarized light passes through the reflective polarizing plate 14. Thereafter, the light is converted into clockwise or counterclockwise circularly polarized light by the first quarter-wave plate 301, reflected by the reflective electrode 13, and returned to the first quarter-wave plate 301. Since the polarization direction of the circularly polarized light reflected by the reflective electrode 13 is reversed, the polarized light that has passed through the first quarter-wave plate 301 is reflected by the reflective polarizing plate 14. This reflected light again passes through the first quarter-wave plate 301, becomes circularly polarized light, and is reflected again by the reflective electrode 13. When the circularly polarized light passes through the quarter wavelength plate again, it becomes linearly polarized light that coincides with the transmission axis of the reflective polarizing plate 14, is converted into circularly polarized light by the second quarter wavelength plate 15, and is absorbed by the polarizing plate 16. Components that coincide with the axis are absorbed. Although some components are emitted, the attenuated light is finally emitted inside the display device, so that reflection of an external image can be suppressed to the extent that there is no problem in use.

  On the other hand, the light emitted from the light emitting layer 12 is first converted into circularly polarized light or linearly polarized light at the first quarter wavelength plate 301, and the polarized component parallel to the transmission axis of the reflective polarizing plate 14 among the converted components. Passes through the reflective polarizing plate 14, the quarter wavelength plate 15, and the polarizing plate 16, and is emitted from the display device. The remaining polarization component is reflected by the reflective polarizing plate 14, returns toward the first quarter-wave plate 301, and is converted into clockwise or counterclockwise circularly polarized light. This clockwise or counterclockwise circularly polarized light is incident on the first quarter-wave plate 301 again as circularly polarized light that is reflected by the reflective electrode 13 and whose polarization direction is reversed. Then, in the first quarter wavelength plate 301, the light is converted into polarized light having a polarization axis parallel to the reflective polarizing plate 14, passes through the polarizing plate 16, and is emitted from the display device. Therefore, it is possible to effectively utilize the light emitting component from the light emitting layer 12 that could not be used conventionally, and the brightness of the display image can be improved.

In addition, a configuration when the reflective polarizing plate is a circularly polarizing reflective polarizing plate will be described. Here, a case where the reflective polarizing plate 14 has a function of transmitting counterclockwise circularly polarized light and reflecting clockwise circularly polarized light will be described. First, surface observation of the display device, that is, polarized light component (referred to as first polarized light) parallel to the absorption axis of the polarizing plate 16 out of the external light incident from the front side of the polarizing plate 16 is absorbed by the polarizing plate 16, The second polarized light parallel to the transmission axis of the polarizing plate 16 is incident on. The second polarized light passes through the quarter-wave plate 15 and is converted into, for example, clockwise circularly polarized light, so that the second polarized light is absorbed without passing through the polarizing plate 16 as in the first embodiment. The component of the external light incident on the apparatus is not emitted to the outside again, and reflection of an external image can be suppressed.

On the other hand, the light emitted from the light emitting layer 12 is first converted into circularly polarized light, elliptically polarized light or linearly polarized light in the first quarter-wave plate 301, and the circularly polarized light component of the converted component remains as a reflective polarizing plate. 14, the quarter-wave plate 15 and the polarizing plate 16 are emitted from the display device. The remaining polarization component is reflected by the reflective polarizing plate 14, returns to the light emitting layer 12 through the first quarter-wave plate 301, is reflected by the reflective electrode 13, and enters the reflective polarizing plate 14 again. Here, the polarized light that does not pass through the reflective polarizing plate 14 is repeatedly reflected between the reflective polarizing plate 14 and the reflective electrode 13 via the first quarter-wave plate 301. Then, by being repeatedly reflected, the polarization axis is shifted, and the light that has been reflected is transmitted through the reflective polarizing plate 14, passes through the quarter-wave plate 15 and the polarizing plate 16, and is emitted from the display device. For this reason, it becomes possible to effectively utilize the light-emitting components that could not be used conventionally, and the brightness of the display image can be improved.

  In the present embodiment, a prism layer, a scattering layer, or a combination thereof may be provided between the substrate 100 and the first quarter-wave plate 301.

In the display device of the present embodiment, reflection of external video due to reflection of external light on the reflective polarizing plate 14 can be suppressed, and image display characteristics can be improved. Further, by providing a quarter-wave plate between the reflective polarizing plate 14 and the substrate 100, it is possible to prevent external light that has passed through the reflective polarizing plate 14 from returning to the outside of the display device, It is possible to suppress the image reflection and improve the display characteristics of the image. Further, the light emitted from the light emitting layer 12 can be extracted more efficiently, and the brightness of the display image can be improved.

(Embodiment 4)
In this embodiment mode, a display device having a structure in which the light emission direction from the light-emitting layer is different from those in Embodiment Modes 1 to 3 will be described. 4 that are the same as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. FIG. 4 illustrates part of the display device in this embodiment.

  As shown in FIG. 4A, the display device in this embodiment includes a reflective electrode 4001, a light-emitting layer 12, a transparent electrode 4002, a reflective polarizing plate 14, a quarter-wave plate 15, and a polarizing plate over a substrate 100. 16 has a layered structure. In this embodiment mode, light emitted from the light emitting layer 12 is extracted from the transparent electrode 4002 side (the side opposite to the substrate 100). Note that in this embodiment, a single-layer or stacked insulating film may be provided between the transparent electrode 4002 and the reflective polarizing plate 14. Further, a scattering layer such as a prism may be provided between the transparent electrode 4002 and the reflective polarizing plate 14, or a quarter wavelength plate may be further provided.

  In the structure of FIG. 4A, the substrate 100 is not necessarily a transparent substrate because the substrate 100 is not interposed when light emission from the light emitting layer 12 is extracted. For example, a ceramic substrate, a silicon substrate, a metal substrate, a stainless steel substrate, or the like may be used.

With the structure illustrated in FIG. 4A, external light incident on the display device from the polarizing plate 16 side is absorbed by the polarizing plate 16, whereby reflection of an external image can be suppressed.

  On the other hand, the light emitted from the light-emitting layer 12 is repeatedly reflected between the reflective polarizing plate 14 and the reflective electrode 4001, thereby effectively utilizing the light-emitting component from the light-emitting layer 12 that could not be used conventionally. Thus, the brightness of the display image can be improved.

In the display device shown in FIG. 4A, reflection of external video due to reflection of external light on the reflective polarizing plate 14 can be suppressed, and image display characteristics can be improved. In addition, light emitted from the light emitting layer 12 can be extracted efficiently, and a reduction in the brightness of the display image can be suppressed.

Further, a transparent electrode 4003 may be provided instead of the reflective electrode 4001 in FIG. 4A (FIG. 4B). In that case, a reflective polarizing plate, a quarter-wave plate, and a polarizing plate are preferably provided on both sides of the substrate 100. That is, as shown in FIG. 4B, the first polarizing plate 4004, the first quarter-wave plate 4005, the first reflective polarizing plate 4006, the substrate 100, the first transparent electrode 4003, and the light emitting layer 12 are used. The second transparent electrode 4002, the second reflective polarizing plate 14, the second quarter-wave plate 15, and the second polarizing plate 16 are sequentially stacked. In this embodiment mode, light emitted from the light emitting layer 12 is extracted from the transparent electrode 4002 side and the transparent electrode 4003 side. That is, light is extracted from two directions, ie, the substrate 100 side and the opposite side of the substrate 100.

Note that in this embodiment, a single-layer or stacked insulating film may be provided between the transparent electrode 4002 and the reflective polarizing plate 14. Further, a scattering layer such as a prism may be provided between the transparent electrode 4002 and the reflective polarizing plate 14, or a quarter wavelength plate may be further provided.

With the structure illustrated in FIG. 4B, external light incident on the display device from the first polarizing plate 4004 or the second polarizing plate 16 side is absorbed by the first polarizing plate 4004 or the second polarizing plate 16. , It will not be emitted again, and the reflection of external images can be suppressed. In the case where a linearly polarizing reflective polarizing plate is used as the reflective polarizing plate, it is preferable that the first polarizing plate and the second polarizing plate are arranged so that their transmission axes are orthogonal to each other. By arranging the transmission axes to be orthogonal to each other, the light reflected from the first reflective polarizing plate 4006 or the second reflective polarizing plate 14 out of the light emitted from the light emitting layer 12 toward one light emitting surface is returned. It can be efficiently taken out from the light emitting surface on the opposite side. In the case where a circularly polarizing reflective polarizing plate is used as the reflective polarizing plate, it is preferable that the spiral rotation directions of the first reflective polarizing plate and the second reflective polarizing plate are reversed. By arranging the rotation directions to be opposite to each other, light emission from the light emitting layer 12 can be efficiently taken out.

The polarizing plates 16 and 4004 have a function of transmitting linearly polarized light having a vibration plane parallel to the polarization axis and absorbing linearly polarized light having a vibration plane orthogonal to the polarization axis.

In this embodiment, when a linearly polarized reflective polarizer is used as the reflective polarizer, the polarization axis of the reflective polarizer 14 and the slow axis of the quarter wave plate 15 are at an angle of 45 ° or 135 °. The polarization axis of the reflective polarizing plate 4006 and the slow axis of the quarter wave plate 4005 are arranged at an angle of 45 ° or 135 °.

As transparent electrodes 4002 and 4003 in FIGS. 4A and 4B, indium tin oxide (ITO), indium tin oxide containing silicon oxide (ITSO), zinc oxide (ZnO), oxidation Indium zinc oxide (IZO) formed using a target in which 2 to 20 wt% zinc oxide (ZnO) is further mixed with indium oxide containing silicon, zinc oxide containing gallium (GZO), Tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), or the like can be used.

As the reflective electrode 4001 in FIG. 4A, a highly reflective metal is preferably used, and aluminum (Al), silver (Ag), or an AlLi alloy, an MgAg alloy, or the like that includes these is used. it can. The reflective electrode 4001 may have a stacked structure of a highly reflective metal and another electrode material. By forming a thin film (for example, about 5 nm) of an alkali metal or an alkaline earth metal and laminating it with a metal having a high reflectivity, it is possible to improve the electron injecting property.

In the display device of this embodiment, reflection of external video due to reflection of external light on the reflective polarizing plate can be suppressed, and image display characteristics can be improved. Further, the light emitted from the light emitting layer 12 can be extracted efficiently, and the brightness of the display image can be improved.

(Embodiment 5)
In this embodiment, a manufacturing process of a display device having a thin film transistor (TFT) will be described. Note that although a structure in which light emitted from the light emitting layer 12 is extracted only from the substrate 100 side is described in this embodiment mode, the present invention is not limited to this structure. A structure in which light emission is extracted from the side opposite to the substrate 100 or a structure in which light emission is extracted from two directions of the substrate 100 side and the side opposite to the substrate 100 may be used.

  First, as shown in FIG. 5A, a substrate 100 is prepared. As the substrate 100, for example, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a quartz substrate, a ceramic substrate, or the like can be used. A substrate made of a synthetic resin having flexibility such as plastic generally tends to have a lower heat resistant temperature than the above substrate, but can be used as long as it can withstand the processing temperature in the manufacturing process. . The surface of the substrate 100 may be planarized by polishing such as a CMP method.

  Next, a base film 101 is formed over the substrate 100 (FIG. 5A). The base film 101 prevents, when glass is used for the substrate 100, alkali metal such as Na or alkaline earth metal contained in the substrate from diffusing into the semiconductor film and adversely affecting the characteristics of the semiconductor element. it can. Therefore, an insulating film such as silicon oxide, silicon nitride, or silicon nitride oxide that can suppress diffusion of alkali metal or alkaline earth metal into the semiconductor film is used. In this embodiment, a silicon nitride oxide film is formed to a thickness of 10 to 400 nm by a plasma CVD method. In addition to plasma CVD, it can also be formed by using a known method such as sputtering or low pressure CVD. Further, although the base film 101 has a single-layer structure in this embodiment mode, it may be formed of two or more layers.

  In the case of using a substrate containing an alkali metal or an alkaline earth metal, such as a glass substrate or a plastic substrate, it is effective to provide the base film 101 from the viewpoint of preventing diffusion of impurities. When diffusion of impurities such as a substrate does not cause any problem, it is not always necessary to provide the substrate.

Next, an amorphous semiconductor film 102 is formed over the base film 101. The amorphous semiconductor film 102 may be formed to a thickness of 25 to 80 nm using silicon or a material containing silicon as a main component (for example, Si _x Ge _1-x ). As a manufacturing method, a known method such as a sputtering method, a low pressure CVD method, or a plasma CVD method can be used.

  Subsequently, the amorphous semiconductor film 102 is crystallized. The amorphous semiconductor film 102 is crystallized by a known crystallization method such as a laser crystallization method, a thermal crystallization method using an RTA or furnace annealing furnace, or a thermal crystallization method using a metal element that promotes crystallization (see FIG. 5 (A)).

  Next, the crystalline semiconductor film is etched into island-shaped semiconductor films 102a to 102c. Subsequently, a gate insulating film 103 is formed so as to cover the island-shaped semiconductor films 102a to 102c (FIG. 5B). The gate insulating film 103 can be formed by stacking a single layer or a plurality of films using, for example, silicon oxide, silicon nitride, silicon nitride oxide, or the like. As a film formation method, a plasma CVD method, a sputtering method, or the like can be used. Here, a sputtering method is used to form an insulating film containing silicon with a thickness of 30 nm to 200 nm.

  Next, a gate electrode is formed over the gate insulating film 103. In this embodiment mode, the gate electrode has a two-layer structure of a first conductive film and a second conductive film. A tantalum nitride (TaN) film is formed as the first conductive layers 104a to 104c, and a tungsten (W) film is formed thereon as the second conductive layers 105a to 105c (FIG. 5C). Both the TaN film and the W film may be formed by sputtering, the TaN film may be formed in a nitrogen atmosphere using a Ta target, and the W film may be formed using a W target.

  Note that although the first conductive layer is TaN and the second conductive layer is W in this embodiment mode, the present invention is not limited to this, and the first conductive layer and the second conductive layer are both Ta, W, and Ti. , Mo, Al, Cu, Cr, Nd, or an alloy material or a compound material containing the element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used. Furthermore, the combination may be selected as appropriate. The film thickness may be in the range of 20 to 100 nm for the first conductive layer and 100 to 400 nm for the second conductive layer. In this embodiment mode, the gate electrode has a two-layer structure; however, the gate electrode may have a single layer structure or a three-layer structure or more.

  Next, an impurity which imparts n-type or p-type conductivity is selectively added to the semiconductor films 102a to 102c using a gate electrode or a resist formed and etched as a mask, and a source region, a drain region, Forms an LDD region and the like.

Next, the resist mask is removed to form a first passivation film 106 (FIG. 5D). As the first passivation film 106, an insulating film containing silicon is formed to a thickness of 100 to 200 nm. As a film forming method, a plasma CVD method or a sputtering method may be used. In this embodiment mode, a silicon oxynitride film is formed by a plasma CVD method. In the case of using a silicon oxynitride film, _{SiH 4,} N 2 O, a silicon oxynitride film made from NH _3, or by _SiH 4, _N form a silicon oxynitride film made from ₂ O by plasma CVD It ’s fine. The production conditions in this case are a reaction pressure of 20 to 200 Pa, a substrate temperature of 300 to 400 ° C., and a high frequency (60 MHz) power density of 0.1 to 1.0 W / cm ² . Alternatively, a silicon oxynitride silicon film formed from SiH ₄ , N ₂ O, and H ₂ may be used as the first passivation film. Needless to say, the first passivation film 106 is not limited to a single layer structure of a silicon oxynitride film as in this embodiment mode, and an insulating film containing other silicon is used as a single layer structure or a stacked structure. May be.

  After that, laser annealing is preferably performed to recover the crystallinity of the semiconductor film and activate the impurity element added to the semiconductor film. In addition, by performing a heat treatment after the first passivation film 106 is formed, the semiconductor film can be hydrogenated simultaneously with the activation process. In the hydrogenation, dangling bonds in the semiconductor film are terminated by hydrogen contained in the first passivation film 106. Here, a SiNO film is used as the passivation film 106, and it may be performed at 410 ° C. in a nitrogen atmosphere.

  In addition, heat treatment may be performed before the first passivation film 106 is formed. However, when the material forming the first conductive layers 104a to 104c and the second conductive layers 105a to 105c is weak against heat, the first passivation film is used to protect the wiring and the like as in this embodiment. It is desirable to perform heat treatment after forming 106. Further, in this case, since there is no first passivation film, naturally hydrogenation using hydrogen contained in the passivation film cannot be performed.

  In this case, hydrogenation using means excited by plasma (plasma hydrogenation) or heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen Hydrogenation by the method may be used. In this manner, TFTs 401 to 403 having a semiconductor film, a gate insulating film, and a gate electrode can be obtained. In addition, the structure of 401-403 is not restricted to the thing of this Embodiment.

  Next, a first interlayer insulating film 107 is formed over the first passivation film 106 (FIG. 5E). As the first interlayer insulating film 107, an inorganic insulating film or an organic insulating film can be used. As the inorganic insulating film, a silicon oxide film formed by a CVD method, a silicon oxide film applied by an SOG (Spin On Glass) method, or the like can be used. As an organic insulating film, polyimide, polyamide, BCB (benzoic acid) is used. A film such as cyclobutene), acrylic or positive photosensitive organic resin, or negative photosensitive organic resin can be used. Alternatively, a stacked structure of an acrylic film and a silicon oxynitride film may be used.

  For the interlayer insulating film, siloxane having a skeleton structure formed of a bond of silicon (Si) and oxygen (O) can be used. In siloxane, an organic group containing at least hydrogen (for example, an alkyl group or an aromatic hydrocarbon) is used as a substituent. Further, a fluoro group may be used as a substituent. Alternatively, an organic group containing at least hydrogen and a fluoro group may be used as a substituent.

  Siloxane polymers can be classified according to their structures into, for example, silica glass, alkylsiloxane polymers, alkylsilsesquioxane polymers, hydrogenated silsesquioxane polymers, hydrogenated alkylsilsesquioxane polymers, and the like. Alternatively, the interlayer insulating film may be formed using a material containing a polymer (polysilazane) having a Si—N bond.

  By using the above material, an interlayer insulating film having sufficient insulation and flatness can be obtained even when the film thickness is reduced. In addition, since the above material has high heat resistance, an interlayer insulating film that can withstand reflow processing in a multilayer wiring can be obtained. Further, since the hygroscopic property is low, an interlayer insulating film with a small amount of dehydration can be formed.

  In this embodiment mode, a siloxane-based polymer is formed as the first interlayer insulating film 107. With the first interlayer insulating film 107, unevenness due to the TFT formed over the substrate can be relaxed and planarized. In particular, since the first interlayer insulating film 107 has a strong meaning of planarization, it is preferable to use an insulating film made of a material that is easily planarized. In addition, silicon oxide containing nitrogen can be used for the first interlayer insulating film. In this case, the first passivation film is not necessarily provided.

  Thereafter, a second passivation film made of a silicon nitride oxide film or the like may be formed over the first interlayer insulating film 107. The film thickness may be about 10 to 200 nm, and the second passivation film can prevent moisture from entering and exiting the first interlayer insulating film 107. In addition, a silicon nitride film, an aluminum nitride film, an aluminum oxynitride film, a diamond-like carbon (DLC) film, and a carbon nitride (CN) film can be used as the second passivation film.

A film formed using an RF sputtering method has high density and excellent barrier properties. For example, when forming a silicon oxynitride film, RF sputtering is performed by flowing N ₂ , Ar, and N ₂ O at a gas flow ratio of 31: 5: 4 using a Si target and a pressure of 0.4 Pa. The film is formed with an electric power of 3000 W. For example, when a silicon nitride film is formed, N ₂ and Ar in the chamber are flowed so that the gas flow rate ratio becomes 1: 1 with a Si target, the pressure is 0.8 Pa, the power is 3000 W, and the film formation temperature is set. Film formation is preferably performed at 215 ° C.

  Next, the first interlayer insulating film 107 and the first passivation film 106 are etched to form contact holes reaching the source region and the drain region. Subsequently, wirings 108a to 108f that are electrically connected to the source region and the drain region are formed (FIG. 6A). As the wirings 108a to 108f, a single layer or a multilayer structure made of one kind of element selected from Al, Ni, W, Mo, Ti, Pt, Cu, Ta, Au, and Mn or an alloy containing a plurality of such elements is used. Can do. Here, it is preferable to form a metal film containing Al. In this embodiment mode, a stacked film of a Ti film and an alloy film containing Al and Ti is formed by etching. Of course, not only a two-layer structure but also a single-layer structure or a laminated structure of three or more layers may be used. Further, the wiring material is not limited to the laminated film of Al and Ti. For example, an Al film or a Cu film may be formed on the TaN film, and a laminated film formed with a Ti film may be etched to form a wiring.

  Next, a second interlayer insulating film 109 is formed so as to cover the wirings 108a to 108f. As the second interlayer insulating film, the same film as the first interlayer insulating film described above can be used. In this embodiment mode, a siloxane polymer is used for the second interlayer insulating film 109. Since siloxane-based polymers have high heat resistance, an interlayer insulating film that can withstand reflow treatment in multilayer wiring can be obtained.

  Subsequently, the second interlayer insulating film 109 is selectively etched to form a contact hole. After that, a wiring 111 for connecting to the wiring 108f is formed. In addition, the pixel electrode 112a is formed at the same time as the wiring 111 (FIG. 6B). The wiring 111 and the pixel electrode 112a use a single layer or a laminated structure made of one kind of element selected from Al, Ni, W, Mo, Ti, Pt, Cu, Ta, Au, and Mn or an alloy containing a plurality of such elements. Can be formed. In this embodiment mode, an Al alloy may be used, and here, Al—Ni—C is used.

  Next, the pixel electrode 112b is formed over the second interlayer insulating film 109, the wiring 111, and the pixel electrode 112a (FIG. 6C). The pixel electrode 112b is formed to be in contact with the second interlayer insulating film 109 at least in a region 119 that does not overlap with the wiring 111 and the pixel electrode 112a. In this embodiment, the pixel electrode 112a and the pixel electrode 112b are formed using a transparent conductive film. For example, other translucent oxide conductive materials such as indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), zinc oxide added with gallium (GZO), etc. It is possible to use materials. Indium tin oxide (ITSO) containing ITO and silicon oxide, or a target formed by mixing 2 to 20 wt% zinc oxide (ZnO) with indium oxide containing silicon oxide may be used. .

  Next, an insulating film (a partition wall or a bank) 116 is formed so as to cover end portions of the pixel electrodes 112a and 112b, and a light emitting layer 114 is formed so as to be in contact with the pixel electrode 112b. The light emitting layer 114 is a layer containing a light emitting substance, and includes, for example, 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 (FIG. 7). Note that the light-emitting layer 114 is not necessarily limited to this structure. It has a single layer or a stacked structure having at least a light emitting layer. FIG. 7 is a schematic cross-sectional view of a light-emitting layer 114 including 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 sandwiched between the pixel electrode 112b and the electrode 115. The figure is shown.

For the hole injection layer 701, it is desirable to use a material having a hole transporting property, a relatively low ionization potential, and a high hole injecting property. Broadly divided into metal oxides, low-molecular organic compounds, and high-molecular organic compounds. As the metal oxide, for example, vanadium oxide, molybdenum oxide, ruthenium oxide, aluminum oxide, or the like can be used. If low molecular weight organic compound, for example, starburst amine typified by m-MTDATA, copper phthalocyanine (abbreviation: Cu-Pc) in the metal phthalocyanine represented, phthalocyanine _{(abbreviation:} H 2 -Pc), 2, A 3-dioxyethylenethiophene derivative or the like can be used. A film in which a low molecular organic compound and the metal oxide are co-evaporated may be used. As a high molecular organic compound, for example, a polymer such as polyaniline (abbreviation: PAni), polyvinyl carbazole (abbreviation: PVK), or a polythiophene derivative can be used. Polyethylene dioxythiophene (abbreviation: PEDOT), which is one of polythiophene derivatives, doped with polystyrene sulfonic acid (abbreviation: PSS) may be used. Further, a benzoxazole derivative and any one or a plurality of materials of TCQn, FeCl ₃ , C _60, or F ₄ TCNQ may be used in combination.

  For the hole-transport layer 702, it is preferable to use a known material that has a high hole-transport property and low crystallinity. For example, an aromatic amine-based compound (that is, a compound having a benzene ring-nitrogen bond) is suitable, for example, 4,4′-bis [N- (3-methylphenyl) -N-phenylamino] biphenyl. (TPD) and its derivative 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] biphenyl (α-NPD). Starburst aromatic amine compounds such as 4,4 ', 4 "-tris (N, N-diphenylamino) triphenylamine (TDATA) and MTDATA can also be used. Alternatively, 4,4 ′, 4 ″ -tris (N-carbazolyl) triphenylamine (abbreviation: TCTA) may be used. As the polymer material, poly (vinyl carbazole) or the like exhibiting good hole transportability can be used.

For the light-emitting layer 703, a material having a large ionization potential and a large band gap is preferably used. For example, tris (8-quinolinolato) aluminum (Alq ₃ ), tris (4-methyl-8-quinolinolato) aluminum (Almq ₃ ), bis (10-hydroxybenzo [η] -quinolinato) beryllium (BeBq ₂ ), bis ( 2-Methyl-8-quinolinolato)-(4-hydroxy-biphenylyl) -aluminum (BAlq), bis [2- (2-hydroxyphenyl) -benzoxazolate] zinc (Zn (BOX) ₂ ), bis [2 A metal complex such as-(2-hydroxyphenyl) -benzothiazolate] zinc (Zn (BTZ) ₂ ) can be used. Various fluorescent dyes (coumarin derivatives, quinacridone derivatives, rubrene, 4,4-dicyanomethylene, 1-pyrone derivatives, stilbene derivatives, various condensed aromatic compounds, etc.) can also be used. Phosphorescent materials such as platinum octaethylporphyrin complex, tris (phenylpyridine) iridium complex, tris (benzylideneacetonato) phenanthrene europium complex can also be used.

  As a host material used for the light-emitting layer 703, a hole transport material or an electron transport material typified by the above example can be used. Alternatively, a bipolar material such as 4,4′-N, N′-dicarbazolylbiphenyl (abbreviation: CBP) can be used.

It is desirable to use a material having a high electron transporting property for the electron transporting layer 704. For example, a metal complex having a quinoline skeleton or a benzoquinoline skeleton represented by Alq ₃ or a mixed ligand complex thereof can be used. Specifically, metal complexes such as Alq ₃ , Almq ₃ , BeBq ₂ , BAlq, Zn (BOX) ₂ , and Zn (BTZ) ₂ can be given. In addition to metal complexes, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD), 1,3-bis [5- (p Oxadiazole derivatives such as -tert-butylphenyl) -1,3,4-oxadiazol-2-yl] benzene (OXD-7), 3- (4-tert-butylphenyl) -4-phenyl-5 -(4-biphenylyl) -1,2,4-triazole (TAZ), 3- (4-tert-butylphenyl) -4- (4-ethylphenyl) -5- (4-biphenylyl) -1,2, Triazole derivatives such as 4-triazole (p-EtTAZ), imidazole derivatives such as TPBI, phenanthroyl such as bathophenanthroline (BPhen) and bathocuproin (BCP) It can be used derivatives.

For the electron injection layer 705, a material having a high electron injection property is preferably used. For example, an ultra-thin film of an insulator such as an alkali metal halide such as LiF or CsF, an alkaline earth halide such as CaF ₂ , or an alkali metal oxide such as Li ₂ O is often used. Alkali metal complexes such as lithium acetylacetonate (abbreviation: Li (acac)) and 8-quinolinolato-lithium (abbreviation: Liq) are also effective. In addition, metal oxides such as molybdenum oxide (MoOx), vanadium oxide (VOx), ruthenium oxide (RuOx), and tungsten oxide (WOx), or benzoxazole derivatives, alkali metals, alkaline earth metals, or transitions Any one or more materials of metal may be included. Further, titanium oxide may be used.

  Note that the light-emitting layer 114 does not necessarily have all of these layers. In this embodiment mode, at least the light-emitting layer 703 may be provided. Further, light emission is not necessarily obtained only from the light-emitting layer 703, and light emission may be obtained from layers other than the light-emitting layer 703 depending on a combination of materials used for other layers. Further, a hole blocking layer may be provided between the light emitting layer 703 and the electron transporting layer 704.

  Note that depending on the color, the phosphorescent material can have a lower driving voltage and higher reliability than the fluorescent material. Therefore, when full-color display is performed using light-emitting elements corresponding to the three primary colors, a combination of a light-emitting element using a fluorescent material and a light-emitting element using a phosphorescent material can reduce the deterioration of the light-emitting element of each color. You may make it arrange | equalize a degree.

  Note that a material that is difficult to be etched is used for the light emitting layer 114 that is closest to the electrode 115 (in this embodiment, the electron injection layer 705), so that the electrode 115 is formed over the light emitting layer 114 by a sputtering method. Sputter damage applied to the layer closest to the electrode 115 (in this embodiment, the electron injection layer 705) can be reduced. Examples of the material that is difficult to etch include metal oxides such as molybdenum oxide (MoOx), vanadium oxide (VOx), ruthenium oxide (RuOx), and tungsten oxide (WOx), or benzoxazole derivatives. . These are preferably formed by vapor deposition. With the above structure, even when the electrode 115 is formed by a sputtering method, sputtering damage to a layer containing an organic substance included in the light-emitting layer 114 can be suppressed, and the selectivity of a substance for forming the electrode 115 is widened.

After that, an electrode 115 is stacked so as to be in contact with the light-emitting layer 114 (FIG. 6D). In this embodiment, the electrode 115 is formed using a reflective conductive film. In addition, since the electrode 115 is used as a cathode, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function is used. For example, alkali metals such as Li and Cs, and alkaline earth metals such as Mg, Ca, and Sr, alloys containing these (Mg: Ag, Al: Li, Mg: In, etc.), and compounds thereof (CaF ₂ , In addition to CaN), rare earth metals such as Yb and Er can be used. When an electron injection layer is provided, other conductive films such as Al can be used.

  Thereafter, a protective layer may be formed on the electrode 115 by vapor deposition using a mask or sputtering. The protective layer protects the electrode 115. If not necessary, it is not always necessary to provide it.

  Next, the sealing substrate 601 is attached with a sealant to seal the light emitting element. In the display device, an outer periphery of a display region is surrounded by a sealant, and the display device is sealed with a pair of substrates 100 and a sealing substrate 601. Note that a filler 602 is filled in a region surrounded by the sealant. Alternatively, the region surrounded by the sealant is filled with a dry inert gas (FIG. 6D).

  Next, the reflective polarizing plate 14, the quarter wavelength plate 15, and the polarizing plate 16 are sequentially laminated on the substrate 100 opposite to the side on which the electrode 115 is formed (FIG. 8). In the present embodiment, when a linearly polarized reflective polarizer is used as the reflective polarizer, the transmission axis of the reflective polarizer 14 and the slow axis of the quarter wave plate 15 form an angle of 45 ° or 135 °. Deploy.

  In the display device having the above structure, by applying a voltage between the pixel electrode 112b and the electrode 115 and supplying a forward bias current to the light-emitting layer 114, light is generated from the light-emitting layer 114, and the light is It can be taken out from the pixel electrode 112b side.

Through the above process, the display device illustrated in FIG. 8 can be manufactured. In the display device of the present embodiment, reflection of external video due to reflection of external light on the reflective polarizing plate 14 can be suppressed, and image display characteristics can be improved. In addition, light emitted from the light-emitting layer 114 can be extracted efficiently, and the brightness of the display image can be improved.

(Embodiment 6)
In this embodiment mode, a panel of the display device described in Embodiment Mode 5 will be described with reference to FIGS.

  A display region 51 having a plurality of pixels including light-emitting elements, gate drivers 52 and 53, a source driver 54, and a connection film 55 are provided over the substrate 50 (FIG. 9A). The connection film 55 is connected to an IC chip or the like.

  FIG. 9B is a cross-sectional view taken along a broken line connecting AB of the panel, and shows a transistor 412, a light-emitting element 413 and a capacitor 416 provided in the display region 51, and an element group 410 provided in the source driver 54.

  A sealant 408 is provided around the display region 51, the gate drivers 52 and 53, and the source driver 54, and the light emitting element 413 is sealed with the sealant 408 and the counter substrate 406. This sealing process is a process for protecting the light-emitting element 413 from moisture. Here, a method of sealing with a cover material (glass, ceramics, plastic, metal, or the like) is used, but a thermosetting resin or ultraviolet light is used. A method of sealing with a curable resin or a method of sealing with a thin film having a high barrier ability such as a metal oxide or a nitride may be used. The element formed on the substrate 50 is preferably formed of a crystalline semiconductor (polysilicon) having favorable characteristics such as mobility as compared with an amorphous semiconductor, so that monolithic formation on the same surface can be achieved. Realized. Since the number of external ICs to be connected is reduced, the panel having the above configuration can be made small, light, and thin. In the present embodiment, the reflective polarizing plate 14, the quarter wavelength plate 15, and the polarizing plate 16 are sequentially laminated on the surface of the substrate 50 opposite to the side on which the light emitting element 413 is formed. ing.

  Note that the display region 51 may be formed of a transistor using an amorphous semiconductor (amorphous silicon) formed over an insulating surface as a channel portion, and a circuit for controlling the display region 51 may be formed of an IC chip. An amorphous semiconductor can be easily formed on a large-area substrate by using the CVD method and does not require a crystallization step, so that an inexpensive panel can be provided. At this time, if a conductive layer is formed by a droplet discharge method typified by an ink jet method, a cheaper panel can be provided. Further, the IC chip may be bonded onto the substrate 50 by a COG (Chip On Glass) method, or may be bonded to the connection film 55 connected to the substrate 50.

  Here, FIGS. 10A and 10B show a state where a chip-like IC (IC chip) is mounted on an element substrate over which a display region having a plurality of pixels is formed. In FIG. 10A, a display region 51 and gate drivers 52 and 53 are formed on a substrate 50. A source driver formed on the IC chip 58 is mounted on the substrate 50. Specifically, a source driver formed on the IC chip 58 is bonded to the substrate 50 and electrically connected to the display area 51. In addition, the power supply potential, various signals, and the like are supplied to the display area 51, the gate drivers 52 and 53, and the source driver formed on the IC chip 58 through the connection film 55.

  In FIG. 10B, a display region 51 and gate drivers 52 and 53 are formed on a substrate 50. The source driver formed on the IC chip 59 is further mounted on the connection film 55 mounted on the substrate 50. A power supply potential, various signals, and the like are supplied to the display area 51, the gate driver 52, and the source driver formed on the IC chip 59 through the connection film 55.

  The IC chip mounting method is not particularly limited, and a known COG method, wire bonding method, TAB method, or the like can be used. Further, the position where the IC chip is mounted is not limited to the position shown in FIG. 10 as long as electrical connection is possible. Further, although FIG. 10 shows an example in which only the source driver is formed with an IC chip, the gate driver may be formed with an IC chip, and the controller, CPU, memory, etc. may be formed with an IC chip and mounted. Anyway. Further, instead of forming the entire source driver or gate driver with an IC chip, only a part of the circuits constituting each driving circuit may be formed with an IC chip.

  Note that by separately forming and mounting an integrated circuit such as a driver circuit using an IC chip, the yield can be increased as compared with the case where all the circuits are formed over the same substrate as the pixel portion. The process can be easily optimized according to the characteristics.

  Note that although not shown in FIG. 10, a protective circuit may be provided over a substrate over which a display region is formed. Since the discharge path can be secured by the protection circuit, the semiconductor element formed on the substrate is deteriorated or broken down due to noise of the signal and the power supply voltage or charge charged to the insulating film for some reason. Can be prevented. Specifically, in the case of FIG. 10A, a protective circuit can be connected to the wiring that electrically connects the connection film 55 and the display region 51. Furthermore, there are wiring that electrically connects the connection film 55 and the IC chip 58 on which the source driver is formed, wiring that electrically connects the connection film 55 and the gate drivers 52 and 53, and a source driver. The wiring (source line) that electrically connects the formed IC chip 58 and the display area 51, and the wiring (gate line) that electrically connects the gate drivers 52 and 53 and the display area 51, A protection circuit can be connected to each.

In the display device of the present embodiment, reflection of external video due to reflection of external light on the reflective polarizing plate 14 can be suppressed, and image display characteristics can be improved. In addition, light emitted from the light emitting element 413 can be extracted efficiently, and the brightness of the display image can be improved.

(Embodiment 7)
In this embodiment, an example of an electronic device including the display device described in any of Embodiments 1 to 6 will be described with reference to FIGS.

  A television shown in FIG. 11A includes a main body 8001, a display portion 8002, and the like. The display portion 8002 includes a display device having a reflective polarizing plate, a quarter wavelength plate, and a polarizing plate. By including the display portion 8002 including the display device, it is possible to provide a television in which external image reflection is suppressed and image display characteristics are improved. In addition, light emitted from the light-emitting layer can be efficiently extracted, and a television in which the brightness of a display image is improved can be provided.

  An information terminal device illustrated in FIG. 11B includes a main body 8101, a display portion 8102, and the like. Display portion 8102 has a display device having a reflective polarizing plate, a quarter-wave plate, and a polarizing plate. By including the display portion 8102 having the display device, it is possible to provide an information terminal device that suppresses reflection of an external video and improves image display characteristics. In addition, it is possible to provide an information terminal device in which light emitted from the light emitting layer can be efficiently extracted and the brightness of the display image is improved.

  A video camera shown in FIG. 11C includes a main body 8201, a display portion 8202, and the like. Display portion 8202 has a display device having a reflective polarizing plate, a quarter-wave plate, and a polarizing plate. By including the display portion 8202 including the display device, it is possible to provide a video camera that suppresses reflection of external video and improves image display characteristics. In addition, it is possible to provide a video camera in which light emitted from the light emitting layer can be efficiently extracted and the brightness of the display image is improved.

  A telephone shown in FIG. 11D includes a main body 8301, a display portion 8302, and the like. Display portion 8302 has a display device having a reflective polarizing plate, a quarter-wave plate, and a polarizing plate. By including the display portion 8302 including the display device, it is possible to provide a telephone in which external image reflection is suppressed and image display characteristics are improved. In addition, it is possible to efficiently extract light emitted from the light-emitting layer, and it is possible to provide a telephone in which the brightness of a display image is improved.

  A portable television shown in FIG. 11E includes a main body 8401, a display portion 8402, and the like. Display portion 8402 includes a display device having a reflective polarizing plate, a quarter-wave plate, and a polarizing plate. By including the display portion 8402 including the display device, it is possible to provide a portable television in which external image reflection is suppressed and image display characteristics are improved. In addition, light emitted from the light-emitting layer can be efficiently extracted, and a portable television in which the brightness of a display image is improved can be provided. In addition, televisions can be used in a wide range from small-sized televisions mounted on portable terminals such as cellular phones, medium-sized televisions that can be carried, and large-sized televisions (for example, 40 inches or more). A display device can be applied.

  In addition, the electronic device which concerns on this invention is not limited to FIG. 11 (A)-(E), The thing which has a display apparatus which has a reflective polarizing plate, a quarter wavelength plate, and a polarizing plate in a display part is contained. .

  As described above, an electronic apparatus that includes a display unit having a display device having a reflective polarizing plate, a quarter-wave plate, and a polarizing plate to suppress reflection of an external image and improve image display characteristics. Can be provided. In addition, light emitted from the light-emitting layer can be extracted efficiently, and an electronic device with improved brightness of a display image can be provided.

The schematic diagram of the cross section of a display apparatus. The schematic diagram of the cross section of a display apparatus. The schematic diagram of the cross section of a display apparatus. The schematic diagram of the cross section of a display apparatus. 10A and 10B illustrate an example of a manufacturing process of a display device. 10A and 10B illustrate an example of a manufacturing process of a display device. 10A and 10B illustrate an example of a manufacturing process of a display device. FIG. 6 illustrates a structure of a light-emitting layer included in a display device. The figure which shows the panel of a display apparatus. The figure which shows the panel of a display apparatus. FIG. 10 illustrates an electronic device using a display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transparent electrode 12 Light emitting layer 13 Reflective electrode 14 Reflective polarizing plate 15 Wavelength plate 16 Polarizing plate 100 Substrate

Claims (7)

A first quarter wave plate provided on the first absorbing polarizer;
A first reflective polarizing plate provided on the first quarter-wave plate;
A transparent substrate provided on the first reflective polarizing plate;
A first transparent electrode provided on the transparent substrate;
A light emitting layer provided on the first transparent electrode;
A second transparent electrode provided on the light emitting layer;
A second reflective polarizing plate provided on the second transparent electrode;
A second quarter-wave plate provided on the second reflective polarizing plate;
A second absorbing polarizer provided on the second quarter-wave plate;
Between the second transparent electrode and the second reflective polarizing plate, a scattering layer in which a plurality of different particles having different refractive indexes from the film are diffused in the film ,
The first reflective polarizer and the second reflective polarizer are linear polarizers,
The transmission axis of the first absorption polarizing plate and the slow axis of the first quarter-wave plate are at an angle of 45 °,
The transmission axis of the first absorption polarizer and the transmission axis of the first reflection polarizer are parallel,
The transmission axis of the second absorption polarizing plate and the slow axis of the second quarter-wave plate are at an angle of 45 °,
The transmission axis of the second absorption polarizer and the transmission axis of the second reflection polarizer are parallel,
The display device, wherein an absorption axis of the first absorption polarizing plate and an absorption axis of the second absorption polarizing plate are orthogonal to each other. A first quarter wave plate provided on the first absorbing polarizer;
A first reflective polarizing plate provided on the first quarter-wave plate;
A transparent substrate provided on the first reflective polarizing plate;
A first transparent electrode provided on the transparent substrate;
A light emitting layer provided on the first transparent electrode;
A second transparent electrode provided on the light emitting layer;
A second reflective polarizing plate provided on the second transparent electrode;
A second quarter-wave plate provided on the second reflective polarizing plate;
A second absorbing polarizer provided on the second quarter-wave plate;
Between the second transparent electrode and the second reflective polarizing plate, a scattering layer in which a plurality of different particles having different refractive indexes from the film are diffused in the film ,
The first reflective polarizer and the second reflective polarizer are circular polarizers,
The display device according to claim 1, wherein the spiral direction of the first reflective polarizer and the spiral direction of the second reflective polarizer are opposite to each other. A first quarter wave plate provided on the first absorbing polarizer;
A first reflective polarizing plate provided on the first quarter-wave plate;
A transparent substrate provided on the first reflective polarizing plate;
A thin film transistor having a semiconductor film having a source region or a drain region provided on the transparent substrate;
An interlayer insulating film provided on the thin film transistor and having a contact hole reaching the source region or the drain region;
A wiring electrically connected to the source region or the drain region provided on the interlayer insulating film;
A first transparent electrode provided on the interlayer insulating film and the wiring;
A light emitting layer provided on the first transparent electrode;
A second transparent electrode provided on the light emitting layer;
A second reflective polarizing plate provided on the second transparent electrode;
A second quarter-wave plate provided on the second reflective polarizing plate;
A second absorbing polarizer provided on the second quarter-wave plate;
Between the second transparent electrode and the second reflective polarizing plate, a scattering layer in which a plurality of different particles having different refractive indexes from the film are diffused in the film ,
The first reflective polarizer and the second reflective polarizer are linear polarizers,
The transmission axis of the first absorption polarizing plate and the slow axis of the first quarter-wave plate are at an angle of 45 °,
The transmission axis of the first absorption polarizer and the transmission axis of the first reflection polarizer are parallel,
The transmission axis of the second absorption polarizing plate and the slow axis of the second quarter-wave plate are at an angle of 45 °,
The transmission axis of the second absorption polarizer and the transmission axis of the second reflection polarizer are parallel,
The display device, wherein an absorption axis of the first absorption polarizing plate and an absorption axis of the second absorption polarizing plate are orthogonal to each other. A first quarter wave plate provided on the first absorbing polarizer;
A first reflective polarizing plate provided on the first quarter-wave plate;
A transparent substrate provided on the first reflective polarizing plate;
A thin film transistor having a semiconductor film having a source region or a drain region provided on the transparent substrate;
An interlayer insulating film provided on the thin film transistor and having a contact hole reaching the source region or the drain region;
A wiring electrically connected to the source region or the drain region provided on the interlayer insulating film;
A first transparent electrode provided on the interlayer insulating film and the wiring;
A light emitting layer provided on the first transparent electrode;
A second transparent electrode provided on the light emitting layer;
A second reflective polarizing plate provided on the second transparent electrode;
A second quarter-wave plate provided on the second reflective polarizing plate;
A second absorbing polarizer provided on the second quarter-wave plate;
Between the second transparent electrode and the second reflective polarizing plate, a scattering layer in which a plurality of different particles having different refractive indexes from the film are diffused in the film ,
The first reflective polarizer and the second reflective polarizer are circular polarizers,
The display device according to claim 1, wherein the spiral direction of the first reflective polarizer and the spiral direction of the second reflective polarizer are opposite to each other. In any one of Claims 1 thru | or 4 ,
A display device, wherein a third quarter-wave plate is formed between the second transparent electrode and the second reflective polarizing plate. In any one of Claims 1 thru | or 5 ,
At least one of the first quarter wavelength plate or the second quarter wavelength plate is a broadband quarter wavelength plate having an effect as a quarter wavelength plate in a visible light range. Characteristic display device. An electronic apparatus comprising the display device according to any one of claims 1 to 6 .

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