JP2002083677A - Luminescence device and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element, having higher luminous efficiency than the conventional ones by enhancing the light-extraction efficiency, and to provide a backlight and of a frontlight for a liquid crystal display of a field sequential driving, by using the organic EL element. SOLUTION: Attention is paid to a guided wave light, emitted from the organic EL element. By using the guided wave light, it becomes possible to produce the organic high EL element, having higher luminous efficiency from the conventional ones. By applying such organic EL element, the backlight and the frontlight that are bright and have low power consumption can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electroluminescence (Electroluminescence).
e: a light-emitting device including an element (hereinafter, referred to as “organic EL element”) in which a thin film (hereinafter, referred to as “organic EL layer”) made of an organic compound from which an organic compound is obtained is sandwiched between electrodes. In particular, the present invention relates to a light emitting device using light that can be extracted from a direction along an interface between an organic EL layer and an electrode (hereinafter, referred to as a “lateral direction”). Note that a light-emitting device in this specification refers to a light-emitting device using an EL element, preferably an organic EL element, as a light-emitting element.

According to the present invention, a light emitting device using an organic EL element is used for an electro-optical device, preferably a backlight or a front light of a liquid crystal display device. Note that an electro-optical device refers to a device which performs light and dark display by applying an electric signal.

[0003]

2. Description of the Related Art Liquid crystal display devices are widely used in portable applications and personal computers because of their light weight and low power consumption.

In a liquid crystal display, three primary colors, red,
A field sequential system in which green and blue light sources are sequentially changed in emission color and turned on to perform color display has attracted attention. The field sequential system eliminates the need for a color filter required in a conventional liquid crystal display device, and is expected to provide a brighter display than in the past (Monthly F
PD Intelligence 1999.7. P70-73).

In the field sequential system, in one frame for forming one image, subframes for displaying red, green, and blue are provided, and a light source is turned on in accordance with the display color of the subframe. As a light source of a field sequential type backlight or front light, a light emitting diode and an EL element are widely used because they can be switched at a level of several μsec.

When an EL element is used as a light source in a field sequential system, light emitted in a planar manner from the substrate surface on which the EL element is formed is used.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light source using an organic EL element having a higher luminous efficiency and a higher brightness than conventional ones by increasing the light extraction efficiency. Another object of the present invention is to perform display by a field sequential method using a light source with high luminance and high response speed by using an organic EL element having higher luminous efficiency than the conventional one.

The light emission mechanism of the organic EL element is such that electrons injected from the cathode and holes injected from the anode recombine at the light emission center in the organic EL layer to form excitons, and the excitons form the bases. It is said to emit energy when returning to the state.

The structure of the organic EL element is mainly such that a transparent electrode (for example, IT) is formed on a glass substrate or a plastic substrate (hereinafter simply referred to as “substrate”).
O), an organic EL layer, and a cathode material are stacked, and a counter substrate is attached thereto. Since a material that does not transmit visible light is used for the cathode, photons generated in the organic EL layer are extracted through the organic EL layer, the transparent electrode layer, and the substrate layer, and are used as light emitting elements.

Here, the ratio of the number of photons taken out of the organic EL device to the number of injected carriers (hereinafter referred to as “external quantum efficiency”) is expressed by the following equation (Reference). 2: "The remaining important issues and strategies for practical use of organic LED elements", edited by Organic Electronics Materials Research Society, Bunshin Publishing, pp. 106-107).

[0011]

(Equation 1)

[0012] Each symbol is η _ext : external quantum efficiency, χ: 0 if light emission from a singlet excited state.
25, taking into account the light emission from the triplet excited state, 1, Φ
: Quantum yield (the ratio of photons generated without photoemission in the organic EL layer to the number of excitons generated by the recombination of carriers, up to 1), γ: Carrier balance factor (The balance of the injected electrons and holes, at most 1), η _e : represents the extraction efficiency.

Χ and Φ are numerical values specific to the organic EL layer material used. γ is a factor determined by the device structure of the organic EL element, the type of electrode, and the like. That is, these numerical values approach 1 depending on the selection and combination of the organic EL layer material and the electrode material. On the other hand, the extraction efficiency η _e is the proportion of generated photons that can be extracted to the outside of the device, and is determined due to the different refractive indexes unique to the organic EL layer, the transparent electrode layer, and the substrate layer.

From equation (1), the external quantum efficiency can be increased by increasing any of χ, Φ, γ, and η _e . When the external quantum efficiency is increased, the luminous efficiency is also improved, so that a light-emitting device that consumes less power and is bright can be manufactured. A high-efficiency light-emitting element utilizing triplet emission is an example in which χ is increased (Reference 3: T. Tsut).
sui, M .; -J. Yang, M .; Yahir
o, K. Nakamura, T .; Watana
be, T.S. Tsuji, Y .; Fukuda,
T. Wakimoto and S.M. Miyagu
chi, “High Quantum Effici
ency in Organic Light-Emi
toting Devices with Iridiu
m-Complex as a Triplet Em
issue Center ", Japanes J
own of Applied Physic
s, Vol. 38, pp. L1502-L150
4 (1999)).

However, at present, the value of the extraction efficiency η _e is said to be only about 20% in the organic EL device (Reference 4: CF Madigan,
M. -H. Lu and J.J. C. Sturm,
“Improvement of output co
upling efficiency of orga
nic light-emitting diodes
by backside substrate mo
modification ”, AppliedPhysi
cs Letters, Vol. 76, No.
13, 1650-1652 (2000)). That is, in the organic EL device, the direction between the anode and the cathode (hereinafter, referred to as the direction between the anode and the cathode)
This indicates that the amount of light that can be extracted in the “vertical direction”, that is, the planar light emission generated from the substrate surface is 20% of the entire generated light. Therefore, no matter how much the material is devised, the conventional technology has a limitation that the external quantum efficiency is at most 20%.

For this reason, even when an organic EL element which emits light in a planar manner is used as a light source for a field-sequential type backlight or front light, since the extraction efficiency is low, the luminance of light emitted from the organic EL element is increased. It becomes difficult.

A liquid crystal display device is often used for portable applications, and a backlight or a front light needs to emit light with high luminance even with limited power consumption. That is, in the organic EL element, it is necessary to increase the extraction efficiency as compared with the related art.

[0018]

In the organic EL device, the limit of the extraction efficiency of about 20% means that when light is going to pass from a material having a high refractive index to a material having a low refractive index, the light must be incident at a certain angle or more. It is derived from the phenomenon of total reflection that appears. That is, for example, a transparent electrode (IT
If O) 1103 is used, the remaining 80% of the generated light is theoretically totally reflected at the interface between the transparent electrode (ITO) 1103 and the substrate 1104 or the interface between the substrate 1104 and the outside of the element.

Since the cathode 1101 does not transmit light, the totally reflected light is reflected again by the cathode 1101, and by repeating the light, travels in the lateral direction of the organic EL element (see FIG. 11A). . Alternatively, FIG.
As described above, there is also light that is taken out of the device in the lateral direction before reflection by the cathode 1101 occurs. These lights are called guided lights. The transparent electrode (IT
O) 1103 has a refractive index larger than that of the organic EL layer 1102, and the transparent electrode (ITO) 1103 and the organic EL layer 11
In FIG. 11, for convenience, the transparent electrode (ITO) 1103 and the organic EL layer 11
The expression of refraction occurring between 02 is omitted.

Since the thickness of the substrate 1104 (millimeter to submillimeter order) is much larger than the thickness of the organic EL layer 1102 (submicron order), FIG.
In (a), α≪β. Accordingly, most of the guided light actually extracted to the outside of the element is extracted in the path of β, that is, the light extracted from the substrate 1104 portion. In the pattern of FIG. 11B, more light is extracted from the substrate 1104.

As described above, the thickness of the substrate 1104 and the organic E
Considering the difference in the thickness of the L layer 1102, most of the guided light is extracted not from the organic EL layer 1102 but from the substrate 1104 layer in the lateral direction. The guided light traveling through the substrate 1104 layer travels at an angle close to parallel to the surface of the substrate 1104, that is, since the angle θ in FIG. 11C is small, total reflection does not occur at the end surface of the substrate 1104. Light can be extracted almost completely.

Therefore, the present inventor paid attention to guided light emitted from the organic EL element in order to solve the above problems.
Although the cathode 1101 is considered to absorb light to some extent, the present inventor believes that, ultimately, the guided light has higher extraction efficiency than the conventional 20% light that can be extracted in the vertical direction. ing.

Therefore, by using guided light,
It is possible to manufacture an organic EL device having higher external quantum efficiency than before, that is, higher luminous efficiency. By applying such an organic EL element, a backlight or a front light using a light-emitting device which is brighter and consumes less power than conventional light sources can be manufactured.

Conventionally, however, no attention has been paid to guided light. This is because, in an organic EL element, planar layers are stacked in the vertical direction. For example, when the organic EL element is used as a pixel of a display, extracting light in the vertical direction is structurally thinner and the process is easier. This is because a flat panel display can be manufactured.

Since the pixels of the flat panel display are used as planar display elements, light in the vertical direction is used as a flat light source. Since the guided light is emitted in the lateral direction, that is, in the direction along the plane of the planar element, there are many process difficulties in trying to use it as a conventional planar light source. Therefore, if guided light is used, the method of using it as a planar light source, which is conventionally considered for an organic EL element, is not very appropriate, and a new method of using light must be applied.

For these reasons, the present inventor has proposed an organic EL device.
Considering that the layer 1102 has a thickness of only a submicron order, it was considered that the organic EL element using the guided light was suitable for use as a line light source or a point light source.

Therefore, in order to use the guided light as linear light or point-like light without light leakage, a light-reflective substrate 1104 is used, or the periphery of the substrate 1104 is covered with a light-reflective member. A method of completely blocking the light emitted from the vertical direction by the method was used. Thus, an organic EL device in which the direction in which light is emitted is limited to only the horizontal direction can be manufactured. In addition, the light reflectivity in this specification refers to a property of reflecting at least visible light, as represented by various metals.

Further, since the organic EL element is difficult to use as a light emitting element of a flat light source, a device structure different from a conventional light emitting device using a flat light source is required. According to the present invention, a light source for displaying an image in a field sequential system using the light guide wave of the organic EL element is provided.

FIG. 1 shows an example of the configuration of the present invention. A transparent anode layer 102 is provided on a substrate layer 101. A first organic EL layer 103a, a second organic EL layer 103b, and a third organic EL layer 103c are provided on the transparent anode layer. A first cathode layer 104a is formed on the first organic EL layer. A second cathode layer 104 on the second organic EL layer
b is formed. A third cathode layer 104c is formed on the third organic EL layer. Further, a lamp reflector 107 made of a light-reflective member is formed below the substrate layer.

In FIG. 1, the cathode layer uses a light-reflective material. A device in which a substrate layer 101, a substrate layer 105, and a sealant 106 are added as constituent elements to an organic EL element including an anode, a cathode, and an organic EL layer is referred to as a light emitting device.

As an example of the emission color, the first organic EL layer 1
03a emits red light. Second organic EL layer 103
b emits green light. The third organic EL layer 103c emits blue light. The first organic EL layer 103a, the second
The organic EL layer 103b and the third organic EL layer 103c sequentially emit light, whereby the emission color of the light-emitting device changes, and a field-sequential light source in which three colors of light are turned on during one frame can be obtained. . The first organic EL layer 103a, the second organic EL layer 103b, and the third
It is desirable that the material of the organic EL layer 103c is appropriately selected and the color purity is as high as possible.

First organic EL layer 103a, second organic E layer
The light emitted from the L layer 103b and the third organic EL layer 103c is reflected by the cathode layer or the lamp reflector 107, or is totally reflected at the interface between the substrate layer 101 and the transparent anode layer 102, so that guided light is emitted. Can be taken out from the side.

By applying a DC voltage to the first cathode layer, the second cathode layer or the third cathode layer and the transparent anode film 102, the organic EL layer emits light and the light 108 is emitted from the end of the substrate layer 101. Is emitted. Since the organic EL layer, the cathode layer, and the transparent anode film are formed in a linearly elongated rectangle, the substrate layer 1
The linear light 108 emits from the end of the line 01.

The light emitted from the end of the substrate layer is converted into planar light 110 by the flat light guide plate 109. Ink dots or projections are formed on the lower surface of the flat light guide plate so that the intensity of light emitted to the upper surface of the flat light guide plate is uniform. Note that the upper surface of the flat light guide plate refers to the surface on the observer side. The lower surface of the flat light guide plate refers to a surface opposite to the upper surface of the flat light guide plate. As shown in FIG.
09, the lamp reflector 107 and the light emitting device are referred to as a backlight in this specification.

The light emitted from the backlight enters the liquid crystal display device 111. In the liquid crystal display device 111, a polarizing plate 112 is attached to a surface of a liquid crystal panel 113 through which light from a backlight enters and exits.

In the present invention, the light utilization efficiency of the EL element is increased by using the light guided by the organic EL element as the light source. By using such a light source for a field-sequential type backlight or front light, bright display with low power consumption can be performed.

In the organic EL device shown in FIG. 1, the substrate layer 101 for forming the organic EL device may be made of plastic or the like. Thereby, the weight of the light emitting device can be reduced.
In addition, by manufacturing the liquid crystal panel 111 using a plastic substrate, a display device including a liquid crystal display device and a backlight can be reduced in weight.

FIG. 1 shows the first organic EL layer and the second organic EL layer of the present invention.
FIG. 6 is a schematic diagram of a backlight used in a field sequential system using an organic EL element in which an organic EL layer and a third organic EL layer are formed in a rectangular shape. The present invention can be applied not only to backlights but also to front lights.

The configuration of the present invention will be described in detail with reference to the following embodiments and examples.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a light emitting device disclosed in the present invention using an organic EL element capable of positively utilizing guided light as light emission will be described. FIG. 3 is a schematic perspective view of the light emitting device and the lamp reflector shown in FIG. Note that in FIG. 3, a portion where light is led out (hereinafter, referred to as a “light extraction port”) is in front of the drawing.

FIG. 3 shows a substrate layer 301, an organic EL layer and electrodes 302a to 302c, a glass substrate layer 303, a sealant 3
4 shows a light-emitting device consisting of a light-emitting device 04. Organic EL layer and electrode 30
2a emits red light. Organic EL layer and electrode 302
b emits green light. Organic EL layer and electrode 302c
Emits blue light. In FIG. 3, an organic EL film that emits short-wavelength light is provided on the side near the light extraction port. This is because, when light of a short wavelength with respect to the emission wavelength is incident on the organic EL film, the EL film is excited by the energy of the light,
This is because light may be emitted without applying a DC voltage.

To effectively use the light emitted from the organic EL layer, the periphery of the organic EL element is covered with a lamp reflector 305. With such a lamp reflector and a light emitting device, guided light is emitted from the end of the substrate layer 301. The organic EL element is used as a backlight or a front light of a liquid crystal display device so that a linear light is emitted from the direction of a light outlet from an elongated rectangular shape.

In FIG. 3, a DC voltage is applied to the organic EL layer and the electrodes 302a to 302c by the drive circuit 306 to sequentially emit green, red and blue light. An example of a method of applying a DC voltage to the organic EL element will be described in a first embodiment.

The organic EL element disclosed in FIGS. 1 and 3 includes a first organic EL layer 103a, a second organic EL layer 103b, and a third organic EL layer 103 which emit blue, green, and red light on a single substrate layer 101.
The organic EL layer 103c of FIG. In contrast, FIGS. 6 and 7 show one type of organic E for one organic EL element.
An L layer is formed, and the periphery of the organic EL element is covered with a light-reflective member to form a lamp reflector. Thus, it is possible to prevent, for example, light emitting red light from being incident on the organic EL layer for emitting another color and causing color mixture.

In the light emitting device shown in FIG. 6, the first substrate layer 2
A first light-transmitting first anode layer 202a, a first organic EL layer 203a, and a first cathode layer 204a are sequentially formed on the light-emitting element 01a. In addition, a light-transmitting second anode layer 202b, a second organic EL layer 203b, and a second cathode layer 204b are sequentially formed on the second substrate layer 201b. In addition, a light-transmitting third anode layer 202c is sequentially formed over the third substrate layer 201c.
A third organic EL layer 203c and a third cathode layer 204c are formed. In addition, the substrate layer 205 is bonded to the organic EL element using a sealing agent 206 so as not to absorb moisture.

As an example of the emission color, the first organic EL layer 2
03a emits red light. Second organic EL layer 203
b emits green light. The third organic EL layer 203c emits blue light. A light reflecting member 207 surrounds a light emitting device that emits each color.

The light generated in the organic EL layer is reflected at a light reflecting member or at the interface between the cathode layers 204a to 204c.
It can be extracted from the lateral direction as guided light. Also,
The light-reflective member 207 has a function of preventing emitted light from entering the organic EL layer for displaying another color and causing color mixture.

Then, light 208 is sequentially emitted from the side surface of the first substrate layer 201a, the second substrate layer 201b, or the third substrate layer 201c, and a linear light source is obtained. It is also possible to arrange a plurality of the units shown in FIG. 6 as one unit. Even in the case where a large number of lines are arranged, a lightweight lighting can be provided by applying a material lighter than glass, such as plastic, to the substrate layer.

In FIG. 6, terminals electrically connected to the first to third cathode layers 204a to 204c and the first to third anode layers 202a to 202c in each organic EL element. Is connected to a drive circuit provided outside the light-reflective member, and the first organic EL element of the organic EL element is connected.
The L layer 203a, the second organic EL layer 203b, and the third organic EL layer 203c emit light sequentially at a fixed timing.

FIG. 7 is characterized in that an organic EL element emitting each color is formed in a vertical direction on a single light-reflective substrate layer. The organic EL element shown in FIG. 7 includes a light-reflective substrate layer 902, a first anode layer 903a, and a first organic EL layer 904 sequentially provided on the substrate layer.
a, second cathode layer 901a, second organic EL layer 904
b, second anode layer 903b, third organic EL layer 904
c, and a third cathode layer 901b. Also,
In order to prevent color mixing that occurs when the emitted light is incident on the organic EL film for displaying other colors, not only the first cathode layer 901a and the second cathode layer 901b but also the second anode layer 903
b also has light reflectivity. Further, a sealing material 907 and a substrate layer 908 are provided so that the organic EL layer is not deteriorated by moisture absorption. Further, an insulating film 909 is provided over the substrate layer 902 in contact with the first anode layer 903a. The function of the insulating film will be described later with reference to the top view of FIG.

The first to third organic EL layers are:
Each of them includes a first hole transporting layer 905a to a third hole transporting layer 905c, and a first electron transporting light emitting layer 906a to a third electron transporting light emitting layer 906c.

The light generated in the first to third organic EL layers is divided into a first cathode layer 901 a and a second cathode layer 90.
1b, the second anode layer 903b, and the light-reflective substrate layer 902, and can be extracted from the lateral direction as guided light. The first to third organic EL layers emit red, blue, and green light, respectively. Light emission of each color is sequentially performed at a fixed timing.

FIG. 21 is a top view of FIG. A section obtained by cutting the top view of FIG. 21 along a dashed line FF ′ corresponds to the dashed line FF ′ of the cross-sectional view of FIG. In FIG. 21, when the substrate layer is a conductor, the insulating film 909 (not shown) is in contact with the substrate layer so that the first anode layer and the transparent electrode are not short-circuited because the substrate layer has light reflectivity. Form the first anode layer on the insulating film
903a and transparent electrodes 910a to 910c are provided. And the first
And a first organic EL film 904a is formed.
Next, the first cathode layer 901a indicated by a thick line is formed so that a part thereof is electrically connected to the transparent electrode 910c. Next, a second organic EL film 904b (not shown) is formed above the first organic EL film at the same position as the first organic EL film. Then, a second anode layer 903b indicated by a thin line is formed so that a part thereof overlaps the transparent electrode 910b. next,
The third organic EL film 904c (not shown) is
It is formed above the film at the same position as the first organic EL film.
Finally, a second cathode layer 901b indicated by a dotted line is formed so that a part thereof overlaps the transparent electrode 910a.

If electrodes and an organic EL film are formed as shown in the top view of FIG. 21, a DC voltage can be applied to a desired organic EL film by selecting an electrode to which a voltage is applied by a drive circuit. For example, a DC voltage can be applied to the first organic EL film by applying a DC voltage to the transparent electrode 910c and the first anode 903a.

The structure shown in FIG. 7 has an advantage over the structure shown in FIG. 6 in that the organic EL layer which emits red, blue and green light is provided between a pair of substrate layers, so that the process is simple. However, materials that can be used for the light-reflective substrate layer 902 include:
Because it is considered a shiny material (such as metal)
FIG. 6 seems to be more appropriate when an element using plastic is used for the substrate layer. In addition, the sealant 90
7, the emitted light is absorbed, and therefore, a sealant having low light absorption is preferably used.

In the light emitting device of FIG. 8, the first anode layer 1003a and the first organic EL layer 100 are in contact with the substrate layer 1002.
4a, second cathode layer 1001a, second organic EL layer 10
04b, second anode layer 1003b, third organic EL layer 1
004c and a third cathode layer 1001b. Here, the cathode layer and the anode layer have light reflectivity.
Further, a lamp reflector is provided around the light emitting device as necessary.

The first organic EL layer 1004a emits red light. The second organic EL layer 1004b emits green light. The third organic EL layer 1004c emits blue light. The first to third organic EL layers 1004a to 1004c include hole transport layers 1005a to 1005c and electron transport layers 1006a to 1006c.

The light generated in the organic EL layer is applied to the substrate layer 100
1, first cathode layer 1001a, second cathode layer 1001
b, first anode layer 1003a, second anode layer 1003b
And can be extracted from the lateral direction as guided light.

The structure shown in FIG. 8 can be manufactured by the same process as that shown in FIG.
Using the element, a flexible light-emitting device can be manufactured. Therefore, by selecting a material so that the hole injection property derived from the combination of the HOMO level of the organic EL layer and the work function of the light-reflective anode layer is an appropriate combination, cost and characteristics can be reduced. This is a better device than those shown in FIGS.

The electrode shape of the organic EL element in FIG. 8 may be manufactured according to the top view in FIG.

As shown in FIG. 9, a light emitting device having a curved surface can be manufactured by using a flexible substrate such as plastic. The light-emitting device that emits each color is covered with the light-reflective member 301 to prevent the emitted light from being incident on the organic EL layer for displaying other colors and causing color mixture. Further, a terminal is provided in contact with the cathode layer and the transparent anode layer of each organic EL element, the terminal is taken out of the light-reflective member, and electrically connected to a driving circuit, and each organic EL layer of the organic EL element is provided. Emits red, blue, and green light sequentially at a certain timing. The configuration of FIG. 9 corresponds to FIGS.
It can be obtained by changing the substrate layer of the light emitting device disclosed in (1) to plastic.

The linear light emitted from the light emitting device disclosed in FIGS. 3 and 6 to 9 of this embodiment is incident on a flat light guide plate, so that it can be used as a field sequential type backlight or front light. it can.

According to the above embodiment, a light source brighter than a light emitting device using a conventional organic EL element can be realized.

By using the organic EL element described above and the light emitting device using the organic EL element, it is possible to achieve a higher extraction efficiency than before. In addition, by utilizing the high-speed response of the organic EL element, it can be used for a backlight or a front light of a field sequential system.

[0065]

Example 1 In this example, the constituent materials of the organic EL element shown in FIG. 1 in the embodiment of the present invention and the method of manufacturing a light emitting device using the constituent materials are shown in FIGS. A specific example will be described with reference to FIG.

Referring to the cross-sectional view of FIG. 4, first, a glass substrate 701 is made of ITO as an anode which is a transparent electrode.
(Indium tin oxide) 702 is formed by sputtering.

The organic EL layer that emits green light includes α-NPD represented by the molecular formula (1) as the hole transport layer 703.
603 is formed. Next, the electron transporting light emitting layer 704a
And a quinacrido represented by the molecular formula (3) using Alq ₃ 604 represented by the molecular formula (2) as a host.
A film doped with ne as a dye is formed. The hole transport layer and the electron transporting light emitting layer are formed by a vacuum deposition method using resistance heating.

[0068]

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[0069]

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[0070]

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The organic EL layer that emits red light includes α-NPD represented by the molecular formula (1) as the hole transport layer 703.
603 is formed. Next, the electron transporting light emitting layer 704b
A film doped with the dye DCM2 represented by the molecular formula (4) is formed by using Alq ₃ 604 represented by the molecular formula (2) as a host. The hole transport layer and the electron transporting light emitting layer are formed by a vacuum deposition method using resistance heating.

[0072]

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As the organic EL layer that emits blue light, after the hole transporting layer 703b, the electron transporting light emitting layer 704c is formed by using the distilarylene derivative represented by the molecular formula (5) as a host and using the molecular formula (6) as a dye A film doped with the indicated distilamine derivative is formed by a vacuum deposition method using resistance heating.

[0074]

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[0075]

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Further, ytterbium (Yb) which does not transmit light is formed as the cathodes 705a to 705c by vapor deposition to obtain an organic EL device having a laminated structure.

Separately from this, a glass coated with a UV curable resin 707 by a dispenser as a sealing material is prepared as a counter substrate 706, and is bonded to a glass substrate 701 on which the organic EL element is laminated, and then irradiated with UV. Adhere. Finally, the periphery of the cell of the organic EL element is covered with a light reflecting member. Thus, the light emitting device shown in FIG. 4 is manufactured. The direction in which the guided light exits is perpendicular to the plane of the drawing.

The electrode structure will be described with reference to the top view of FIG. Anode 702 which is a transparent electrode on a glass substrate 701
a to 702c and transparent electrodes 702d to 702f are formed in an elongated stripe shape. A hole transport layer (not shown) is formed so as to overlap on the anode. The electron transporting light emitting layers 704a to 704c are formed on the hole transporting layer. And, as a cathode, ytterbium (Y
b) 705 is deposited by evaporation.

The transparent electrode 702d and the cathode 705a are electrically connected. Therefore, the transparent electrode 702a and the anode 702a
When a DC voltage is applied during this period, a voltage can be applied to the stacked body of the hole transporting layer 703a and the electron transporting light emitting layer 704a.

Similarly, the anode 702b and the transparent electrode 7
02e, the hole transport layer 703 is applied.
A voltage can be applied to the stacked body of b and the electron transporting light emitting layer 704b. Further, the anode 702c and the transparent electrode 7
By applying the voltage between 02f, a voltage can be applied to the stacked body of the hole transporting layer 703c and the electron transporting light emitting layer 704c.

Anodes 702a to 702c and transparent electrode 70
2d to 702f are electrically connected to a drive circuit, and when driving the liquid crystal display device by the field sequential method, the organic EL layer is selected and a voltage is applied at a certain timing.

The material of the organic EL layer disclosed in this embodiment is as follows.
The present invention can also be applied to the organic EL elements of FIGS. 6 to 8 disclosed in the embodiments.

[Embodiment 2] FIG. 2 shows a light emitting device using the organic EL element of the present invention, and an example in which a flat light guide plate 109 is used as a front light of a reflection type liquid crystal panel 113.

In FIG. 2, a substrate layer 101, a transparent anode layer 102, a first organic EL layer 103a to a third organic EL layer 103c, a first cathode layer 104a to a third cathode layer 104
c, a light emitting device including a substrate layer 105 and a sealant 106 is illustrated. The first organic EL layer 103a emits red light. The second organic EL layer 103b emits green light. The third organic EL layer 103c emits blue light.

In the organic EL device shown in FIG. 2, the light emitted from each organic EL layer emits light of another color.
Light-reflective members 117 are provided in the form of walls in the gaps between the organic EL layers in order to prevent light from entering the layers and causing color mixing.

The first organic EL layer to the third organic EL layer
The light emitted from the layer is reflected by the first to third cathode layers or the light-reflective member 107, or is totally reflected at the interface between the substrate layer 101 and the transparent anode layer 102, so that the light is guided. It can be extracted from the lateral direction as wave light. In FIG. 2, the weight of the light-emitting device can be reduced by using plastic for the substrate layer 101 and the substrate layer 105.

The linear light 108 emitted from the organic EL element
Are incident on the flat light guide plate 109. Protrusions are provided on the lower surface of the flat light guide plate, that is, on the side of the reflective liquid crystal display device 111, and by changing the density of the protrusions, the intensity of the light 110 incident on the reflective liquid crystal display device from the front light is reduced. Be uniform over the entire surface.

In the reflection type liquid crystal display device, a polarizing plate 112 is attached to the upper surface of a reflection type liquid crystal panel 113.
An optical film may be provided between the polarizing plate 112 and the reflective liquid crystal display device for adjusting the contrast. Light 110 incident on a reflective liquid crystal panel from a front light
Passes through the counter electrode 115 and the liquid crystal layer 116, is reflected on the surface of the reflective electrode 114, passes through the flat light guide plate 109, and is visually recognized by an observer.

[Embodiment 3] FIG. 10 shows the relationship between the lighting timing of the backlight of the field sequential system and the display time due to the response of the liquid crystal. Here, as the ferroelectric liquid crystal, as shown in FIG. 10B, a liquid crystal which shows a black level by a voltage of negative polarity and performs gradation display according to an applied voltage with a voltage of positive polarity was used. A method for manufacturing a liquid crystal display device used in this embodiment will be described in detail in Embodiment 5.

The liquid crystal display device is a QVGA (240 × 320)
Pixel) and the gate selection time is 5.0 μsec
It is. The response time of the liquid crystal is the sum of the rise time and the fall time, and is 1.2 msec at a drive voltage of 5 V or less.

In the timing chart shown in FIG. 10A, a gate line is selected during a write time 801 and charges are written to the liquid crystal layer and the storage capacitor. Then, during the white display period 802, the liquid crystal displays a predetermined gradation according to the value of the positive voltage. During the next erase time 803, the gate line is selected, and during the black display period 804, a voltage having the same absolute value as the voltage applied during the white display period and having the opposite polarity is applied.

When the black screen is displayed over the entire screen, the emission color of the backlight changes. As described above, the backlight is switched when the image signal written in the white display period 802 is erased, so that it is possible to prevent color mixture of the backlight in the display image.

[Embodiment 4] In this embodiment, a method of manufacturing an active matrix substrate in an active matrix type liquid crystal display device used in a field sequential system will be described. An embodiment of the present invention will be described with reference to FIGS. Here, a method for simultaneously manufacturing a pixel TFT and a storage capacitor in a pixel portion and a TFT of a driver circuit provided in the periphery of a display region will be described in detail according to steps.

In this embodiment, a method of manufacturing a pixel TFT which is a switching element of a pixel portion and a TFT of a driving circuit (a signal line driving circuit, a scanning line driving circuit, etc.) provided around the pixel portion on the same substrate. Will be described according to the steps. However, for the sake of simplicity, a CMOS circuit, which is a basic configuration circuit, is provided in the drive circuit section for the pixel T in the pixel section.
In the FT, an n-channel TFT is illustrated by a cross section along a certain path.

First, as shown in FIG. 12A, oxidation is performed on a substrate 400 made of glass such as barium borosilicate glass represented by Corning # 7059 glass or # 1737 glass or aluminoborosilicate glass. A base film 401 including an insulating film such as a silicon film, a silicon nitride film, or a silicon oxynitride film is formed. For example, a silicon oxynitride film 401a manufactured from SiH ₄ , NH ₃ , and N ₂ O by a plasma CVD method has a thickness of 10 to 200 nm.
(Preferably 50-100 nm) and Si
Silicon oxynitride hydride film 4 made of H ₄ and N ₂ O
01b is 50 to 200 nm (preferably 100 to 150 nm).
(nm). In this embodiment, the base film 401 is used.
Is shown as a two-layer structure, but may be formed as a single-layer film of the insulating film or a structure in which two or more layers are stacked.

The island-shaped semiconductor films 402 to 406 are formed of a crystalline semiconductor film formed by using a semiconductor film having an amorphous structure by a laser crystallization method or a known thermal crystallization method. The thickness of the island-shaped semiconductor films 402 to 406 is 25 to 80 nm.
(Preferably 30 to 60 nm). The material of the crystalline semiconductor film is not limited, but is preferably formed of silicon or a silicon germanium (SiGe) alloy.

In order to form a crystalline semiconductor film by a laser crystallization method, a pulse oscillation type or continuous emission type excimer laser, a YAG laser, or a YVO ₄ laser is used.
In the case of using these lasers, it is preferable to use a method in which laser light emitted from a laser oscillator is linearly condensed by an optical system and irradiated on a semiconductor film. The conditions for crystallization are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is set to 30 Hz, and the laser energy density is set to 100 to 400 mJ / cm ² (typically, 20 to 400 mJ / cm ² ).
0 to 300 mJ / cm ² ). When a YAG laser is used, its second harmonic is used and a pulse oscillation frequency of 1 is used.
-10kHz, laser energy density 300 ~
600 mJ / cm ² may (typically 350~500mJ / cm ²⁾ to. And a width of 100 to 1000 μm, for example 400
A laser beam condensed linearly in μm is irradiated over the entire surface of the substrate, and the superposition rate (overlap rate) of the linear laser beam at this time is set to 80 to 98%.

Next, a gate insulating film 407 covering the island-like semiconductor films 402 to 406 is formed. Gate insulating film 407
Uses a plasma CVD method or a sputtering method and has a thickness of 4
The insulating film containing silicon is formed to have a thickness of 0 to 150 nm. In this embodiment, a silicon oxynitride film with a thickness of 120 nm is formed. Needless to say, the gate insulating film is not limited to such a silicon oxynitride film, and another insulating film containing silicon may be used as a single layer or a stacked structure. For example, when a silicon oxide film is used, TEOS (Tetraethyl Ortho Silicate) is used by a plasma CVD method.
And O ₂ , a reaction pressure of 40 Pa and a substrate temperature of 300 to
400 ° C., high frequency (13.56 MHz) power density 0.
It can be formed by discharging at 5 to 0.8 W / cm ² .
The silicon oxide film thus produced is
Good characteristics as a gate insulating film can be obtained by thermal annealing at 00 to 500 ° C.

[0099] Then, a first conductive film 408 and a second conductive film 409 for forming a gate electrode are formed over the gate insulating film 407. In the present embodiment, the first conductive film 40
8 is formed of TaN to a thickness of 50 to 100 nm, and the second conductive film 409 is formed of W to a thickness of 100 to 300 nm.

When a W film is formed, it is formed by a sputtering method using W as a target. Alternatively, it can be formed by a thermal CVD method using tungsten hexafluoride (WF ₆ ). In any case, it is necessary to lower the resistance in order to use it as a gate electrode.
It is desirable to set the resistance to Ωcm or less. The resistivity of the W film can be reduced by enlarging the crystal grains. However, when there are many impurity elements such as oxygen in W, the crystallization is inhibited and the resistance is increased. From this, when using the sputtering method,
By using a W target having a purity of 99.9999% and forming a W film with sufficient care so as not to mix impurities from the gas phase during film formation, the resistivity is 9 to 20 μΩc.
m can be realized.

In this embodiment, the first conductive film 408 is used.
Is TaN and the second conductive film 409 is W, but each is an element selected from Ta, W, Ti, Mo, Al, and Cu.
Alternatively, it may be formed of an alloy material or a compound material containing the above 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. As a combination other than this embodiment, the first conductive film is formed of tantalum (Ta), the second conductive film is formed of W, and the first conductive film is formed of tantalum nitride (TaN). There is a combination in which the second conductive film is made of Al, the first conductive film is made of tantalum nitride (TaN), and the second conductive film is made of Cu.

Next, resist masks 410 to 41 are used.
7, and a first etching process for forming an electrode and a wiring is performed. In this embodiment, the ICP (Inductively
An etching gas is mixed by using a coupled plasma (inductively coupled plasma) etching method, and plasma is generated by applying 500 W of RF (13.56 MHz) power to the coil-type electrode at a pressure of 1 Pa. 100 W of RF (13.56 MHz) power is also applied to the substrate side (sample stage), and a substantially negative self-bias voltage is applied. By appropriately selecting an etching gas, the W film and the TaN film are etched to the same extent.

Under the above-mentioned etching conditions, by making the shape of the resist mask suitable, the ends of the first conductive layer and the second conductive layer are tapered due to the effect of the bias voltage applied to the substrate side. It becomes a taper shape with an angle of 15 to 45 °. In order to perform etching without leaving a residue on the gate insulating film, the etching time may be increased by about 10 to 20%. Since the selectivity of the silicon oxynitride film to the W film is 2 to 4 (typically 3), the exposed surface of the silicon oxynitride film is etched by about 20 to 50 nm by the over-etching process. Thus, the first shape conductive layers 419 to 425 (first conductive layers 419 a to 425 a) including the first conductive layer and the second conductive layer are formed by the first etching process.
And second conductive layers 419b to 425b). 41
Reference numeral 8 denotes a gate insulating film, which has first shape conductive layers 419 to 419.
The region not covered with 425 is etched by about 20 to 50 nm to form a thinned region.

Then, a first doping process is performed, and n
An impurity element for imparting a mold is added. (FIG. 12 (B))
The doping may be performed by an ion doping method or an ion implantation method. The condition of the ion doping method is that the dose amount is 1
× 10 ^{13 to} 5 × 10 ¹⁴ atoms / cm ² and an acceleration voltage of 60
It is performed as １００100 keV. An element belonging to Group 15 of the periodic table, typically phosphorus (P) or arsenic (As) is used as the n-type impurity element. Here, phosphorus (P) is used. In this case, the conductive layers 419 to 423 serve as a mask for the impurity element imparting n-type, and the first impurity regions 427 to 430 are formed in a self-aligned manner. The first impurity regions 427 to 430 have 1 × 10 ²⁰ to 1 × 10 ²¹ atomic.
An impurity element imparting n-type is added in a concentration range of / cm ³ .

Next, a second etching process is performed as shown in FIG. Using an ICP etching method, a reactive gas is introduced into the chamber, a predetermined RF power (13.56 MHz) is supplied to the coil-type electrode, and plasma is generated. On the substrate side (sample stage), a lower RF (13.56 MHz)
z) Power is applied, and a lower self-bias voltage is applied than in the first etching process. The W film is anisotropically etched to obtain second shape conductive layers 494 to 499.

Further, a second doping process is performed as shown in FIG. In this case, the dose is lower than that of the first doping process, and n is set as a condition of a high acceleration voltage.
Doping with an impurity element for giving a mold. For example, the acceleration voltage is set to 70 to 120 keV and the dose is set to 1 × 10 ¹³ / cm ² , and a new impurity region is formed inside the first impurity region formed in the island-shaped semiconductor film in FIG. Form. The doping is performed in the second shape conductive layers 494-498.
Is used as a mask for the impurity element, and the region below the first conductive layers 494a to 498a is doped so that the impurity element is added. Thus, the second impurity regions 608 to 608 overlapping with the first conductive layers 494a to 498a are formed.
612 are formed. The impurity element imparting n-type is the second element.
To a concentration of ^{1 × 10 17 ~1 × 10 18} atomic / cm 3 in the impurity region.

As shown in FIG. 13A, the gate insulating film 43
2 is simultaneously etched to form the first conductive layer T
Since the aN is etched and receded, third shape conductive layers 433 to 438 (first conductive layers 433a to 438a and second conductive layers 433b to 438b) are formed. 432
Denote gate insulating films, and third shape conductive layers 433 to 43
The area not covered by 8 is further etched by about 20 to 50 nm to form a thinned area.

In FIG. 13A, the first conductive layer 43
Third impurity regions 600 to 60 overlapping 3a to 437a
3 and fourth impurity regions 604 to 607 outside the third impurity region. Thus, the concentration of the impurity element imparting n-type in the third impurity region and the fourth impurity region becomes substantially equal to the concentration of the impurity element imparting n-type in the second impurity region.

Then, as shown in FIG. 13B, fourth impurity regions 454 to 456 having a conductivity type opposite to one conductivity type are formed in the island-shaped semiconductor film 403 forming the p-channel TFT. Using the conductive layer 434 having the third shape as a mask for an impurity element, an impurity region is formed in a self-aligned manner. At this time, the entire surface of the island-shaped semiconductor films 402, 404, 405, and 406 forming the n-channel TFT is covered with resist masks 451 to 453. Impurity region 4
Phosphorus is added at different concentrations to 55 to 456, but the impurity concentration is set to 2 × in any region by ion doping using diborane (B ₂ H ₆ ).
It is set to be 10 ^{20 to} 2 × 10 ²¹ atoms / cm ³ .

Through the above steps, an impurity region is formed in each island-like semiconductor film. The conductive layers 433 to 437 overlapping with the island-shaped semiconductor film function as gate electrodes of the TFT. 437 functions as a capacitor wiring, and 438 functions as a wiring in a driving circuit.

FIG. 13 shows a diagram for controlling the conductivity type.
As shown in (C), a step of activating the impurity element added to each of the island-shaped semiconductor films is performed. This step is performed by a thermal annealing method using a furnace annealing furnace. In addition, a laser annealing method or a rapid thermal annealing method (RTA method) can be applied. In the thermal annealing method, the oxygen concentration is 1 ppm or less, preferably 0.1 ppm.
The heat treatment is performed at 400 to 700 ° C., typically 500 to 600 ° C. in a nitrogen atmosphere of ppm or less. In this embodiment, the heat treatment is performed at 500 ° C. for 4 hours. However, 433-4
When the wiring material used for 38 is weak to heat, it is preferable to activate after forming an interlayer insulating film (mainly composed of silicon) to protect the wiring and the like.

Further, a heat treatment is performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% of hydrogen to hydrogenate the island-like semiconductor film. In this step, dangling bonds in the semiconductor film are terminated by thermally excited hydrogen. As another means of hydrogenation,
Plasma hydrogenation (using hydrogen excited by plasma) may be performed.

Then, as shown in FIG. 14, a first interlayer insulating film 472 is formed of a silicon oxynitride film with a thickness of 100 to 200 nm. A second layer made of an organic insulating material thereon;
An acrylic resin film or a polyimide resin film having a thickness of 1.8 μm is formed as the interlayer insulating film 473 of FIG. Next, an etching step for forming a contact hole is performed.

Next, a conductive metal film is formed by a sputtering method or a vacuum evaporation method. This is because a Ti film is formed to a thickness of 50 to 150 nm, a contact is formed with a semiconductor film forming a source or drain region of the island-shaped semiconductor film, and the Ti film is formed.
300-400nm of aluminum (Al) on the film
And a Ti film or titanium nitride (Ti
N) A film was formed with a thickness of 100 to 200 nm to form a three-layer structure.

Then, a source wiring 474 for forming a contact with the source region of the island-shaped semiconductor film in the drive circuit portion.
To 476, and drain wirings 477 to 479 forming a contact with the drain region are formed.

In the pixel section, the connection electrode 48
0, a gate wiring 481, a drain electrode 482, and a second electrode 492 are formed.

The connection electrode 480 electrically connects the source wiring 483 and the first semiconductor film 484. Although not shown, the gate wiring 481 is electrically connected to the first electrode 485 through a contact hole. Drain electrode 48
2 is electrically connected to the drain region of the first semiconductor film 484. The second electrode 492 is electrically connected to the second semiconductor film 493, and the second electrode 492 is connected to the storage capacitor 505.
Function as an electrode.

Thereafter, a transparent conductive film is formed on the entire surface, and a pixel electrode 491 is formed by a patterning process using a photomask and an etching process. Pixel electrode 491
Are formed on the second interlayer insulating film 473 and the pixel TFT
Are provided so as to overlap with the drain electrode 482 and the second electrode 492 to form a connection structure.

The material of the transparent conductive film is indium oxide (I
n ₂ O ₃ ) and indium tin oxide alloy (In ₂ O ₃ —S
nO ₂ ; ITO) or the like can be formed by a sputtering method, a vacuum evaporation method, or the like. The etching of such a material is performed using a hydrochloric acid-based solution. However, in particular, since etching of ITO easily generates residues, an indium oxide-zinc oxide alloy (In ₂ O ₃ —ZnO) may be used in order to improve the etching processability. Since the indium zinc oxide alloy has excellent surface smoothness and excellent thermal stability with respect to ITO, it is possible to prevent a corrosion reaction with Al contacting the end face of the drain electrode 482. Similarly,
Zinc oxide (ZnO) is also a suitable material, and zinc oxide (ZnO: Ga) to which gallium (Ga) is added to increase the transmittance and conductivity of visible light can be used.

Thus, an active matrix substrate corresponding to a transmission type liquid crystal display device can be completed.

As described above, the n-channel TFT 5
01, p-channel TFT 502, n-channel TFT
A driver circuit portion including the pixel circuit 503 and a pixel portion including the pixel TFT 504 and the storage capacitor 505 can be formed over the same substrate. In this specification, such a substrate is referred to as an active matrix substrate for convenience.

The n-channel TFT 501 in the driver circuit portion includes a channel formation region 468, a third impurity region 441 (GOLD region) overlapping with the conductive layer 433 forming a gate electrode, and a fourth impurity formed outside the gate electrode. A region 446 (LDD region) and a first impurity region 427 functioning as a source or drain region are provided.
The channel forming region 46 is formed in the p-channel TFT 502.
9, a fifth impurity region 456 overlapping with the conductive layer 434 forming the gate electrode, and a sixth impurity region 455 functioning as a source or drain region. In the n-channel TFT 503, a channel formation region 470, a third impurity region 443 overlapping with the conductive layer 435 forming a gate electrode (GOLD region), and a fourth impurity region 448 formed outside the gate electrode (LDD region) And a first impurity region 429 functioning as a source region or a drain region.

In the pixel TFT 504 in the pixel portion, a channel forming region 471, a third impurity region 444 (GOLD region) overlapping the conductive layer 436 forming a gate electrode, and a fourth impurity region 449 formed outside the gate electrode. (LD
D region) and a first impurity region 430 functioning as a source region or a drain region. Further, an impurity element imparting n-type is added to the semiconductor film 430 functioning as one electrode of the storage capacitor 505. A storage capacitor is formed by the capacitor wiring 437 and an insulating layer (the same layer as the gate insulating film) therebetween.

The top view of FIG. 15 is indicated by a chain line BB ′ and a chain line C-
The cross section cut along the line C ′ corresponds to the dashed line B-
B ′ corresponds to a cross section cut along a chain line CC ′.

[Embodiment 5] A part of the method of manufacturing the active matrix substrate manufactured in Embodiment 4 can be applied to a reflection type liquid crystal display device.

First, the process is performed according to FIGS. 12 to 13 of the first embodiment to obtain the structure shown in FIG.

Then, as shown in FIG. 18, a first interlayer insulating film 472 is formed of a silicon oxynitride film with a thickness of 100 to 200 nm. A second layer made of an organic insulating material thereon;
An acrylic resin film or a polyimide film having a thickness of 1.8 μm is formed as the interlayer insulating film 473 of FIG. Next, an etching step for forming a contact hole is performed.

Next, a conductive metal film is formed by a sputtering method or a vacuum evaporation method. This is because a Ti film is formed to a thickness of 50 to 150 nm, a contact is formed with a semiconductor film forming a source or drain region of the island-shaped semiconductor film, and the Ti film is formed.
300-400nm of aluminum (Al) on the film
And a Ti film or titanium nitride (Ti
N) A film was formed with a thickness of 100 to 200 nm to form a three-layer structure.

Then, a source wiring 474 for forming a contact with the source region of the island-shaped semiconductor film in the drive circuit portion.
To 476, and drain wirings 477 to 479 forming a contact with the drain region are formed.

In the pixel portion, the connection electrode 48
0, a gate wiring 481, and a drain electrode 482 are formed. In this embodiment, the drain electrode 482 has a function as a pixel electrode of the reflection type liquid crystal display device.

[0131] As for the storage capacitor, the second semiconductor film 493 and the first electrode 485 provided for each pixel are used as electrodes. The gate insulating film (not shown) functions as a dielectric film of the storage capacitor. The second semiconductor film 493 is a pixel electrode 491
And the same potential as. The first electrode 485 has the same potential as the gate wiring.

The connection electrode 480 electrically connects the source wiring 483 and the first semiconductor film 484. Although not shown, the gate wiring 481 is electrically connected to the first electrode 485 through a contact hole. Drain electrode 48
2 is electrically connected to the drain region of the first semiconductor film 484. Further, the drain electrode 482 is formed of the second semiconductor film 4
The second semiconductor film 493 is electrically connected to the second semiconductor film 93 and functions as an electrode of the storage capacitor 505.

Thus, an active matrix substrate corresponding to a reflection type liquid crystal display device can be completed.

As described above, the n-channel TFT 5
01, p-channel TFT 502, n-channel TFT
A driver circuit portion including the pixel circuit 503 and a pixel portion including the pixel TFT 504 and the storage capacitor 505 can be formed over the same substrate. In this specification, such a substrate is referred to as an active matrix substrate for convenience.

The n-channel TFT 501 in the driver circuit portion includes a channel formation region 468, a third impurity region 441 (GOLD region) overlapping with the conductive layer 433 forming a gate electrode, and a fourth impurity formed outside the gate electrode. A region 446 (LDD region) and a first impurity region 427 functioning as a source or drain region are provided.
The channel forming region 46 is formed in the p-channel TFT 502.
9, a fifth impurity region 456 overlapping with the conductive layer 434 forming the gate electrode, and a sixth impurity region 455 functioning as a source or drain region. In the n-channel TFT 503, a channel formation region 470, a third impurity region 443 overlapping with the conductive layer 435 forming a gate electrode (GOLD region), and a fourth impurity region 448 formed outside the gate electrode (LDD region) And a first impurity region 429 functioning as a source region or a drain region.

In the pixel TFT 504 in the pixel portion, a channel formation region 471, a third impurity region 444 (GOLD region) overlapping the conductive layer 436 forming a gate electrode, and a fourth impurity region 449 formed outside the gate electrode. (LD
D region) and a first impurity region 430 functioning as a source region or a drain region. Further, an impurity element imparting n-type is added to the semiconductor film 430 functioning as one electrode of the storage capacitor 505. A storage capacitor is formed by the capacitor wiring 437 and an insulating layer (the same layer as the gate insulating film) therebetween.

The top view of FIG. 17 is indicated by the dashed line DD ′ and the dashed line E−.
The cross section cut along the line E ′ corresponds to the dashed line D- in the cross-sectional view of FIG.
D ′, corresponding to a cross section cut along a chain line EE ′.

[Embodiment 6] In this embodiment, a method for manufacturing a liquid crystal display device used in a field sequential system will be described. FIG. 16 shows a liquid crystal display device using a TFT element as a switching element.

[0139] A light-shielding film 509 is formed on a substrate 508 as an opposite substrate. Chromium (Cr) or the like can be used for the light shielding film. The thickness of the light shielding film is desirably 100 nm to 200 nm.

A transparent conductive film 510 is formed on the light shielding film 509. The transparent conductive film is indium tin oxide (ITO)
A membrane can be used. In order to keep the transmittance of visible light high, the thickness of the ITO film is desirably 100 nm to 120 nm.

The alignment films 511 to 5 are provided on the element substrate and the counter substrate.
12 are formed. The thickness of the alignment film is 30 nm to 80
nm is good. The alignment film is, for example, AL105 manufactured by JSR Corporation.
4 can be used. When an alignment film having a low pretilt is used, C2 alignment can be stabilized and alignment defects can be suppressed.

The alignment films 511 to 512 are rubbed. By making the rubbing directions parallel, domains due to alignment defects can be prevented.

After the opposing substrate and the element substrate are bonded to each other by the sealant 513, the opposing substrate and the element substrate are separated.
The sealant is a UV-curable sealant, XN manufactured by Mitsui Toatsu.
R5610-1H1 is used. Into the sealant, a silica ball, which is a silica-based spacer, manufactured by Sekiyu Kagaku Co., Ltd. is placed. The diameter of the ball is 1.5 μm.

The ferroelectric liquid crystal material 514 is heated to an isotropic phase and injected. After confirming that the liquid crystal material has been injected over the entire surface of the liquid crystal panel, the liquid crystal is gradually cooled to room temperature at 0.01 to 3 ° C./min. Good orientation is obtained by slow cooling.

The liquid crystal material 514 displays a black level irrespective of the voltage when a negative voltage is applied among the ferroelectric liquid crystals, and performs gray scale display according to the voltage when a positive voltage is applied. Use something. For example, a ferroelectric liquid crystal manufactured by Clariant can be used.

After confirming that the liquid crystal material has been injected, the UV
The injection port of the liquid crystal display device is sealed with a hardening type sealant.

Then, a polarizing plate (not shown) is attached by a known technique. Through the above steps, a liquid crystal display device is completed.

In the field sequential system, three-color display is performed in 16.6 msec for one frame, so that the liquid crystal responds during 5.5 msec for the sub-frame.
It is necessary to perform gradation display according to the voltage and then return to the black level. For this reason, it is desirable to use a smectic liquid crystal having spontaneous polarization with a high response speed.

As the smectic liquid crystal, since a liquid crystal display device is driven using TFT elements, it is desirable to use a liquid crystal capable of analog gradation. For example, it is preferable to use a liquid crystal exhibiting a V-shaped voltage transmittance characteristic having no threshold value, in which a phase transition precursor phenomenon occurs remarkably. As such a liquid crystal material, MX-Y102 manufactured by Mitsubishi Gas Chemical Company, Inc.
Can be used.

[Embodiment 7] A liquid crystal display device or a light emitting device formed by carrying out any one of the above embodiments 1 to 6 can be used for various electro-optical devices. That is, the present invention can be applied to all electronic devices in which the electro-optical device is incorporated in a display unit.

Examples of such electronic devices include a video camera, a digital camera, a head-mounted display (goggle type display), a car navigation, a car stereo, a personal computer, a portable information terminal (a mobile computer, a mobile phone, an electronic book, etc.), and the like. Is mentioned. Examples of these are shown in FIGS.

FIG. 19A shows a personal computer, which comprises a main body 2001, an image input section 2002, and a display section 20.
03, a keyboard 2004 and the like. Display unit 2 of the present invention
003 can be applied.

FIG. 19B shows a video camera, which includes a main body 2101, a display section 2102, an audio input section 2103, operation switches 2104, a battery 2105, and an image receiving section 210.
6 and so on. The present invention can be applied to the display portion 2102.

FIG. 19C shows a mobile computer (mobile computer), which includes a main body 2201, a camera section 2202, an image receiving section 2203, operation switches 2204, a display section 2205, and the like. The present invention can be applied to the display portion 2205.

FIG. 19D shows a goggle type display, which includes a main body 2301, a display portion 2302, and an arm portion 230.
3 and so on. The present invention can be applied to the display portion 2302.

FIG. 19E shows a player using a recording medium (hereinafter, referred to as a recording medium) on which a program is recorded, and includes a main body 2401, a display section 2402, and a speaker section 240.
3, a recording medium 2404, an operation switch 2405, and the like. This player uses a DVD (D
digital Versatile Disc), CD
And the like, it is possible to perform music appreciation, movie appreciation, games, and the Internet. The present invention can be applied to the display portion 2402.

FIG. 19F shows a digital camera, which includes a main body 2501, a display section 2502, an eyepiece section 2503, operation switches 2504, an image receiving section (not shown), and the like. The present invention can be applied to the display portion 2502.

FIG. 20A shows a mobile phone,
01, audio output unit 2902, audio input unit 2903, display unit 2904, operation switch 2905, antenna 2906
And so on. The present invention can be applied to the display portion 2904.

FIG. 20B shows a portable book (electronic book), which includes a main body 3001, display portions 3002 and 3003, a storage medium 3004, operation switches 3005, and an antenna 3006.
And so on. The present invention can be applied to the display units 3002 and 3003.

FIG. 20C shows a display, which includes a main body 3101, a support 3102, a display portion 3103, and the like.
The present invention can be applied to the display portion 3103. The display of the present invention is particularly advantageous when the screen is enlarged, and is advantageous for a display having a diagonal of 10 inches or more (particularly 30 inches or more).

As described above, the applicable range of the present invention is extremely wide, and can be applied to electronic devices in all fields. Further, the electronic apparatus according to the present embodiment can be realized by using any combination of the embodiments 1 to 6.

[0162]

According to the present invention, an organic EL device having higher light extraction efficiency than the conventional one can be manufactured, and a light-emitting device that is bright, consumes less power, and is lightweight can be obtained. Further, since the organic EL element can respond at high speed, such a light emitting device can be used as a light source of a field sequential system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-sectional structure of a backlight using an organic EL element of the present invention.

FIG. 2 is a diagram showing a cross-sectional structure of a front light using the organic EL element of the present invention.

FIG. 3 illustrates a structure of a light-emitting device.

FIG. 4 is a diagram showing a cross-sectional structure of an organic EL element.

FIG. 5 is a diagram showing a top structure of an organic EL element.

FIG. 6 illustrates a cross section of a light emitting device.

FIG. 7 illustrates a cross section of a light emitting device.

FIG. 8 illustrates a cross section of a light emitting device.

FIG. 9 illustrates a structure of a light-emitting device.

FIG. 10 is a diagram showing a timing chart of a field sequential system.

FIG. 11 is a diagram illustrating guided light.

FIG. 12 illustrates a manufacturing method using a cross section of an active matrix substrate.

FIG. 13 illustrates a manufacturing method using a cross section of an active matrix substrate.

FIG. 14 illustrates a manufacturing method using a cross section of an active matrix substrate.

FIG. 15 is a diagram illustrating an upper surface of a pixel portion of an active matrix substrate.

FIG. 16 illustrates a cross section of a liquid crystal display device.

FIG. 17 is a diagram illustrating an upper surface of a pixel portion of an active matrix substrate.

FIG. 18 illustrates a manufacturing method using a cross section of an active matrix substrate.

FIG. 19 illustrates an example of an electronic device.

FIG. 20 illustrates an example of an electronic device.

FIG. 21 illustrates a top view of a light-emitting device.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/30 365 G09F 9/46 Z 9/46 H05B 33/12 B H05B 33/12 C 33/14 A 33/14 G02F 1/1335 530 (72) Inventor Takeshi Nishi 398 Hase, Atsugi-shi, Kanagawa F-Terminator, Semi-Conductor Energy Laboratory Co., Ltd. 2H088 EA37 HA01 MA20 2H091 FA14Z FA23Z FA44X FA44Z FA45Z GA01 LA15 LA30 3K007 AB02 AB03 AB04 BA04 BA05 CC01 DA01 DB03 EB00 GA04 5C094 AA08 AA10 AA15 AA22 AA48 BA03 BA12 BA27 BA43 CA19 CA24 DA02 DA03 DA09 DA13 EA05 EA06 EB02 ED11 FB01 5G435 AA04 AA18 BB12 BB15 BB16 CC09 CC12 DD13 FF22 GG22 FF22

Claims (8)

[Claims] 2. A light emitting device according to claim 1, wherein the light emitted from the light emitting device comprises guided light from an organic EL element, and the organic EL element emits light sequentially changing its emission color. 2. A substrate layer, an anode provided on the substrate layer, a first organic EL layer, a second organic EL layer, and a third organic EL layer provided in contact with the anode. First organic E
A first cathode layer provided on the L layer, a second cathode layer provided on the second organic EL layer, and a third cathode layer provided on the third organic EL layer And a light-reflecting member provided below the substrate layer. 3. A light-reflective substrate layer, and an organic EL element above the substrate layer, wherein the organic EL element has a first anode layer, a first organic EL layer above the substrate layer, Second cathode layer, second organic EL layer, second anode layer, third organic EL
A light-emitting device, wherein the cathode layer and the second anode layer are light-reflective. 4. An organic EL device having a substrate layer and an organic EL element on the substrate layer, wherein the organic EL element has a first anode layer, a first organic EL layer, and a first cathode layer on the substrate layer. , The second organic EL
A light-emitting device, comprising: a layer, a second anode layer, a third organic EL layer, and a second cathode layer, which are stacked in this order, wherein the anode layer and the cathode layer have light reflectivity. 5. A light-emitting device including an organic EL element, wherein the light emitted from the light-emitting device comprises guided light from the organic EL element, the organic EL element sequentially emits light in different emission colors, and uses the emitted light. A liquid crystal display device which performs color display by a field sequential method. 6. A substrate layer, an anode provided on the substrate layer, a first organic EL layer, a second organic EL layer, and a third organic EL layer provided in contact with the anode. First organic E
A first cathode layer provided on the L layer, a second cathode layer provided on the second organic EL layer, and a third cathode layer provided on the third organic EL layer Using a light-emitting device provided with a light-reflective member below the substrate layer, wherein the first organic EL layer, the second organic EL layer,
A liquid crystal display device, wherein the third organic EL layer sequentially emits light, and a color display is performed by a field sequential method using the light emission. 7. A light-reflective substrate layer, and an organic EL element on the substrate layer, wherein the organic EL element has a first anode layer, a first organic EL layer, A second cathode layer,
A second organic EL layer, a second anode layer, a third organic EL layer,
A third cathode layer is stacked in the order of the third cathode layer, and the cathode layer and the second anode layer use a light-emitting device having light reflectivity, and the first organic EL layer and the second organic EL layer of the light-emitting device are used. A liquid crystal display device, wherein an organic EL layer and the third organic EL layer sequentially emit light, and color display is performed by a field sequential method using the emitted light. 8. An organic EL device comprising: a substrate layer; and an organic EL element on the substrate layer, wherein the organic EL element has a first anode layer, a first organic EL layer, and a first cathode layer on the substrate layer. , The second organic EL
A layer, a second anode layer, a third organic EL layer, and a second cathode layer, which are stacked in this order. The anode layer and the cathode layer use a light-emitting device having light reflectivity. A liquid crystal display device, wherein the first organic EL layer, the second organic EL layer, and the third organic EL layer sequentially emit light, and perform color display by a field sequential method using the light emission.