JP2008112112A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device permitting to obtain good visibility and high transmittance. <P>SOLUTION: The light emitting device 1 comprises a TFT 3 prepared on a substrate 2, an insulating film 4 covering the TFT 3, and a structure in which an organic layer 8 is held between an anode 6 which reflects light and a cathode 9 which transmits the light. The anode 6 is electrically connected to the TFT 3 through an opening 5 prepared in the insulating film 4. Since the incident light from the outside of the light emitting device 1 is transmitted mainly through an exposed part of the insulating film 4, good visibility and high transmittance can be obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device.

  An organic LED (Light-Emitting Diode) element is also referred to as an organic EL (Electro Luminescence) element, and is an element using a phenomenon in which light is emitted by excitons generated by recombination of electrons and holes injected into an organic substance. It is.

  In recent years, development of a light-emitting device using this organic LED element, especially a display, has been actively conducted. This is because the organic LED display has a wide viewing angle, a fast response speed, a high contrast, and the like as compared with the liquid crystal display.

  The organic LED element has, for example, a structure in which an organic layer is sandwiched between a transparent electrode and a metal electrode. In this case, light emitted inside the element is extracted outside the element through the transparent electrode. That is, the emitted light is emitted with the same intensity in all directions inside the element, but the light emitted to the metal electrode side is reflected because the metal electrode is not translucent, and the transparent electrode side Taken from.

  On the other hand, an organic LED element in which light is extracted from both sides is also known (for example, see Non-Patent Document 1). In such a double-sided light emitting organic LED element, a transparent material is used for both the anode side and the cathode side. For this reason, at the time of non-light emission, the viewer can see what is behind the organic LED element through the organic LED element.

  FIG. 12 is a partial cross-sectional view of a conventional active matrix type organic LED light emitting device. In this figure, a thin film transistor (hereinafter referred to as TFT in this specification) 103 is formed on a substrate 102 of the organic LED light emitting device 101, and further, a first step covering first step is provided. Insulating film 104 is provided. An opening 105 is provided in the first insulating film 104, and the TFT 103 is electrically connected to the anode 106 through the opening 105. A second insulating film 107 and an organic layer 108 are provided on the first insulating film 104 and the anode 106, and a cathode 109 is further provided on the organic layer 108.

  Transparent materials are used for the substrate 102, the first insulating film 104, the anode 106, the second insulating film 107, the organic layer 108, and the cathode 109. For this reason, the light emitted from the organic layer 108 is extracted from both the anode side and the cathode side. Further, light incident on the organic LED device 101 from the outside passes through a portion of the substrate 102 where the TFT 103 is not provided. Therefore, what is behind the organic LED device is visually recognized through this portion.

  FIG. 13 is a partial cross-sectional view of a conventional segment type organic LED light emitting device. In this figure, an anode 203 is formed on the substrate 202 of the organic LED device 201, and an insulating film 204 for element isolation covers the edge of the anode 203 between the anodes 203. Is provided. An organic layer 205 is provided over the insulating film 204 and the anode 203, and a cathode 206 is provided over the organic layer 205.

  Transparent materials are used for the substrate 202, the anode 203, the insulating film 204, the organic layer 205, and the cathode 206. For this reason, the light emitted from the organic layer 205 is extracted from both the anode side and the cathode side. Moreover, since the light incident on the organic LED device 201 from the outside passes through the organic LED element, the viewer can see what is behind the organic LED device.

Yasuo Nakamura et al., SID 04 DIGEST, p. 1403-1405

  As a method of using the organic LED element, the inventor can see what is behind, so that the display of what is usually behind is visible, and when necessary, the organic LED element is allowed to emit light so that the display can be seen. I thought about making it. However, in this case, the conventional double-sided light emitting organic LED element has a problem that the light emitted to the back surface becomes stray light and hinders visibility. In addition, since the light transmitting portion also serves as the light emitting portion, elements constituting the light emitting portion, that is, an anode, an organic layer, and a cathode are provided in this portion. For this reason, light must pass through these structures, and there is a limit to the improvement in transmittance.

  The present invention has been made in view of these problems. That is, an object of the present invention is to provide a light emitting device capable of obtaining good visibility and high transmittance.

  Other objects and advantages of the present invention will become apparent from the following description.

A first aspect of the present invention includes a plurality of thin film transistors provided on a substrate,
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
There is a portion where the insulating film is exposed between the light emitting elements, and light incident from the outside is mainly transmitted through this portion.

A second aspect of the present invention includes a plurality of thin film transistors provided on a substrate,
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
There is a portion where the insulating film is removed between the light emitting elements, and light incident from the outside is mainly transmitted through this portion.

According to a third aspect of the present invention, a plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
Between the light emitting elements, there is a portion where the light emitting layer is formed on the insulating film, and light incident from the outside mainly transmits through this portion.

A fourth aspect of the present invention includes a plurality of thin film transistors provided on a substrate,
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
The second electrode has a structure in which a semitransparent electrode and a transparent electrode are laminated in order from the light emitting layer side,
Between the light emitting elements, there is a portion where the light emitting layer and the transparent electrode are formed in contact with each other on the insulating film, and light incident from the outside is mainly transmitted through this portion. It is.

According to a fifth aspect of the present invention, a plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
The second electrode has a structure in which a semitransparent electrode and a transparent electrode are laminated in order from the light emitting layer side,
Between the light emitting elements, there is a portion where the transparent electrode is formed on the insulating film, and light incident from the outside mainly transmits through this portion.

According to a sixth aspect of the present invention, a plurality of first electrodes provided on a substrate and transmitting light,
An insulating film provided between the first electrodes;
A light emitting layer provided on the first electrode and the insulating film;
A light emitting device including a plurality of second electrodes provided on the light emitting layer and reflecting light,
There is a portion where the light emitting layer is exposed between the second electrodes, and light incident from the outside is mainly transmitted through this portion.

  In the sixth aspect of the present invention, one of the first electrodes, one of the second electrodes provided at positions corresponding thereto, and the first electrode and the second electrode are sandwiched. A plurality of pixels having the light emitting layer formed may be arranged. At this time, the width of the second electrode is preferably in the range of 20% to 40% of the pitch of the pixels.

  1st-6th aspect of this invention WHEREIN: The said light emitting element can be made into an organic LED element.

  According to the first to sixth aspects of the present invention, it is possible to provide a light emitting device that can obtain good visibility and high transmittance.

  As a method of using the organic LED element in which the object behind can be seen, specifically, the following forms can be considered. For example, a light emitting device using an organic LED element is disposed in front of an instrument panel of a vehicle as viewed from the driver. Usually, the organic LED element is set in a state in which it does not emit light, and the display of the instrument panel behind it is made visible through the light emitting device. Then, if necessary, the organic LED element is caused to emit light so that characters, numbers or figures displayed on the light emitting device can be read.

  The structure of the light emitting device includes, for example, a transparent substrate on the driver side who is a viewer, a sealing gas on the back side, and a first between the transparent substrate and the sealing gas in order from the transparent substrate side. It can be set as the structure which laminated | stacked the transparent electrode, the organic layer, and the 2nd transparent electrode. As the sealing gas, for example, dry nitrogen or dry argon can be used. Further, either the first transparent electrode or the second transparent electrode may be an anode or a cathode.

  With the use method as described above, it is not necessary to read the display from the back side, and it is sufficient to read only from the viewer side. Further, the transmittance of light that enters and exits the organic LED element from the outside does not need to be 100%, and if it is about 70%, it is considered practically sufficient. Thus, as a result of earnest research, the present inventors have found a light emitting device capable of obtaining good visibility and high transmittance in such applications. Hereinafter, the light emitting device of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional view of an active matrix light-emitting device in this embodiment. As shown in this figure, a TFT (Thin Film Transistor) 3 is formed on a substrate 2 of the light emitting device 1, and a first insulating film 4 for covering a step is further provided. In addition, an opening 5 is provided in the first insulating film 4, and the TFT 3 is electrically connected to the anode 6 as the first electrode through the opening 5. In the figure, a gate insulating film and an interlayer insulating film constituting the TFT 3, a wiring connected to the TFT 3, a storage capacitor, and the like are omitted.

  In FIG. 1, the anode 6 is provided above the TFT 3 and is not provided on the first insulating film 4 without the TFT 3. A second insulating film 7 for protecting the end face of the anode 6 is provided on the anode 6. An organic layer 8 is provided on the anode 6 and the second insulating film 7, and a cathode 9 as a second electrode is further provided on the organic layer 8. The anode 6, the organic layer 8, and the cathode 9 constitute an organic LED element as a light emitting element.

  In the present embodiment, the substrate 2, the first insulating film 4, the second insulating film 7, and the organic layer 8 are each made of a material that transmits light. The cathode 9 is made of a material that is transmissive to light, and the anode 6 is made of a material that reflects light such as metal. The anode 6 may have a laminated structure of a transparent conductive film such as ITO and a metal reflective film. Thereby, the light emitted from the organic layer 8 and emitted to the cathode side passes through the cathode 9 and is extracted outside. On the other hand, the light emitted to the anode side is reflected by the anode 6 and travels toward the cathode side, and then passes through the cathode 9 and is extracted to the outside.

  Thus, in the light emitting device of this embodiment, the light emitted from the organic layer is extracted outside only from the surface on the cathode side. Therefore, if the cathode side is the viewer side, light emission occurs only on the viewer side surface, so that the problem that the light emitted to the back surface becomes stray light and the visibility is lowered can be solved. Note that the light extraction efficiency to the viewer side can be improved by optimizing the type and configuration of the members constituting the light emitting device.

  In the present embodiment, the cathode 9 may be either transparent or translucent. When translucent, the light interference effect increases, and this can be used to increase the light extraction efficiency to the viewer. In addition, ITO generally used as a transparent electrode needs to be formed by sputtering, but as a semitransparent electrode, for example, when a thin film (film thickness of about 5 nm to 15 nm) such as MgAg or Al is used, Film formation by vapor deposition is possible. According to the vapor deposition method, damage to the organic layer can be reduced as compared with the sputtering method, which is advantageous in terms of improving element characteristics and reliability. On the other hand, when a semi-transparent electrode is used, the angle dependency of the emission color increases. Therefore, it is preferable to decide whether to select transparent or translucent depending on the application.

  In the present invention, the first electrode may be a cathode and the second electrode may be an anode. That is, the cathode may be a reflective electrode and the anode may be a transparent electrode or a semitransparent electrode. Even in this case, if the anode side is set as the viewer side and the cathode side is set as the back side of the light emitting device, no light is emitted to the back side. it can.

On the other hand, light incident on the light emitting device from the outside is transmitted through the light emitting device other than the portion where a material that reflects light, such as a TFT or an electrode, is used. For example, in FIG. 1, light incident on the light emitting device 1 is transmitted through a portion (region X ₁ ) other than the portion where the TFT 3 and the anode 6 are provided. Here, the region X ₁ includes a portion (region a ₁ ) where only the gate insulating film (not shown), the interlayer insulating film (not shown), and the first insulating film 4 are provided on the substrate ₁ . A portion (region b ₁ ) where the second insulating film 7 is further provided on the first insulating film 4, and an organic layer 8 and a cathode 9 are further provided on the second insulating film 7. It is roughly divided into a portion (region c ₁ ). Among these, the area a ₁ has the largest occupation area, and the area a ₁ is a portion where the insulating film 4 is exposed between the organic LED elements.

On the other hand, in the conventional light emitting device, as described with reference to FIG. 12, the anode 106, the organic layer 108, and the cathode 109 are provided in addition to the insulating film 104 on the substrate 102 where light is transmitted. It has been. For this reason, since the light transmitted through the light-emitting device must pass through these structures, there is a limit in setting the transmittance to a certain value or more. However, according to the light emitting device of the present embodiment, the light has a portion (region X ₁ ) where there is no element constituting the light emitting portion, particularly a portion where only the insulating film is provided on the substrate (region a ₁ ). Since it permeates, it is possible to obtain a higher transmittance than in the past.

FIG. 2 is an example of a partial plan view of the light emitting device of FIG. FIG. 3 is another example of a partial plan view of the light emitting device of FIG. In these drawings, the region Y ₁ includes a first insulating film 4, an anode on the TFT 3, wiring (not shown), storage capacitor (not shown), etc. provided on the substrate 2 in FIG. 6, a portion where the second insulating film 7, the organic layer 8, and the cathode 9 are provided. That is, the region Y _1, while corresponding to the light-emitting portion, an opaque portion for the incident light from the outside.

On the other hand, in FIG. 2 and FIG. 3, region _{X 1} consisting region _{a 1,} b 1, _{c 1} is the transparent portion relative to the incident light from the outside. Therefore, it is possible through the region X _1, viewing those placed on the back of the light-emitting device. The region a ₁ occupying most of the area in the region X ₁ is only a gate insulating film (not shown), an interlayer insulating film (not shown), and the first insulating film 4 on the substrate 2 of FIG. It is a part that is not provided. Therefore, light incident from the outside can pass through the light emitting device with high transmittance.

  The present embodiment is not limited to the example shown in FIG. 1, and various modifications can be made without departing from the spirit of the present invention.

  FIG. 4 shows a modification of the present embodiment. In FIG. 4, the parts denoted by the same reference numerals as those in FIG. 1 are the same.

  The configuration of FIG. 4 is basically the same as the configuration of FIG. 1, but in FIG. 1, the light emitted from the organic layer 8 is one color, whereas in FIG. 4, the organic layers 8R, 8G, The light emission color of 8B is different in that it is red, green, and blue, respectively. In addition, the combination of the color which light-emits by an organic layer may be other than this.

  As described above, according to the present embodiment, the light emitted from the organic layer is extracted to the outside only from either one of the cathode side and the anode side. Therefore, if the light emitting surface is on the viewer side, light emission from the back surface is eliminated, so that the problem of reduced visibility due to light emitted to the back surface can be solved. In addition, since light incident from the outside mainly passes through a portion where only the insulating film is provided on the substrate, the transmittance of incident light can be made higher than before.

Embodiment 2. FIG.
FIG. 5 is a partial cross-sectional view of the active matrix light-emitting device in this embodiment. As shown in this figure, a TFT (Thin Film Transistor) 13 is formed on the substrate 12 of the light emitting device 11, and a first insulating film 14 for covering a step is provided around the TFT 13. ing. An opening 15 is provided in the first insulating film 14, and the TFT 13 is electrically connected to the anode 16 as the first electrode through the opening 15. In the figure, a gate insulating film and an interlayer insulating film constituting the TFT 13, a wiring connected to the TFT 13, a storage capacitor, and the like are omitted.

  As shown in FIG. 5, the present embodiment is characterized in that there is a portion 20 on the substrate 12 where the first insulating film 14 is not provided. This portion 20 can be formed, for example, by etching away from the substrate 12 when the opening 15 is formed in the first insulating film 14.

  In FIG. 5, the anode 16 is provided above the TFT 13 and is not provided on the first insulating film 14 without the TFT 13. That is, the anode 16 is provided corresponding to the position where the TFT 13 is disposed. A second insulating film 17 for protecting the end face of the anode 16 is provided on the anode 16. An organic layer 18 is provided on the anode 16 and the second insulating film 17, and a cathode 19 as a second electrode is further provided on the organic layer 18. The anode 16, the organic layer 18, and the cathode 19 constitute an organic LED element as a light emitting element.

  In the present embodiment, the substrate 12, the first insulating film 14, the second insulating film 17, and the organic layer 18 are each made of a material that transmits light. The cathode 19 is made of a material that is transmissive to light, and the anode 16 is made of a material that reflects light such as metal. Thereby, the light emitted from the organic layer 18 and emitted to the cathode side passes through the cathode 19 and is extracted outside. On the other hand, the light emitted to the anode side is reflected by the anode 16 and travels toward the cathode side, and then passes through the cathode 19 and is extracted outside.

  As described above, in the light emitting device of this embodiment, similarly to Embodiment 1, light emitted from the organic layer is extracted outside only from the surface on the cathode side. Therefore, if the cathode side is the viewer side, light emission occurs only on the viewer side surface and does not occur on the back surface of the light emitting device. Therefore, according to the light emitting device of the present embodiment, it is possible to solve the problem that the light emitted to the back surface becomes stray light and the visibility is lowered. Note that the light extraction efficiency to the viewer side can be improved by optimizing the type and configuration of the members constituting the light emitting device.

  In the present embodiment, the cathode 19 may be either transparent or translucent. When translucent, the light interference effect increases, and this can be used to increase the light extraction efficiency to the viewer. In addition, ITO generally used as a transparent electrode needs to be formed by sputtering, but as a semitransparent electrode, for example, when a thin film (film thickness of about 5 nm to 15 nm) such as MgAg or Al is used, Film formation by vapor deposition is possible. According to the vapor deposition method, damage to the organic layer can be reduced as compared with the sputtering method, which is advantageous in terms of improving element characteristics and reliability. On the other hand, when a semi-transparent electrode is used, the angle dependency of the emission color increases. Therefore, it is preferable to decide whether to select transparent or translucent depending on the application.

  In the present invention, the first electrode may be a cathode and the second electrode may be an anode. That is, the cathode may be a reflective electrode and the anode may be a transparent electrode or a semitransparent electrode. Even in this case, if the anode side is set as the viewer side and the cathode side is set as the back side of the light emitting device, no light is emitted to the back side. it can.

On the other hand, light incident on the light emitting device from the outside is transmitted through the light emitting device other than the portion where a material that reflects light, such as a TFT or an electrode, is used. For example, in FIG. 5, the light incident on the light emitting device 11 is transmitted through a portion (region X ₂ ) other than the portion where the TFT 13 and the anode 16 are provided. In contrast, region Y ₂ of Figure 5, while constituting the light emitting portion, an opaque portion for the incident light from the outside.

The region X ₂ includes a portion (region a ₂ ) where only a gate insulating film (not shown) and an interlayer insulating film (not shown) are formed on the substrate 12, and a _first portion further on these portions. A portion where the insulating film 14 is provided (region b ₂ ), a portion where the second insulating film 17 is further provided on the first insulating film 14 (region c ₂ ), and a second insulating film 17 is further roughly divided into a portion (region d ₂ ) where an organic layer 18 and a cathode 19 are further provided. Among these, the area a ₂ occupies most of the area of the area X ₂ , and the area a ₂ is a portion where the insulating film 14 is removed between the organic LED elements.

In the first embodiment, the portion through which light is transmitted, was predominantly region a ₁ in Fig. 1. Here, the region a ₁ is a portion where only the gate insulating film (not shown), the interlayer insulating film (not shown), and the first insulating film 4 are provided on the substrate 2. On the other hand, the portion through which light is transmitted in the present embodiment is mainly the region a ₂ and the region b ₂ . Here, region b ₂ is formed of a same composition as the region a _1, the region a _2, film corresponding to the first insulating film 4 in the region a ₁ is not provided. Therefore, the transmittance of the light transmitted through the region a ₂ is higher than the transmittance of the light transmitted through the region a _1. Therefore, the light transmittance of the light emitting device as a whole is higher than that of the first embodiment.

  Thus, according to the present embodiment, the light emitted from the organic layer is extracted to the outside only from either one of the cathode side and the anode side. Therefore, if the light emitting surface is on the viewer side, no light is emitted to the back surface, so that the problem of reduced visibility due to the light emitted to the back surface can be solved. In addition, light incident from the outside mainly passes through a portion where only the insulating film is provided on the substrate, but in this embodiment, a thick insulating film (first insulating film in FIG. 2) is formed. Since the area of the portion is reduced, the transmittance of incident light can be further increased as compared with the first embodiment.

Embodiment 3 FIG.
FIG. 6 is a partial cross-sectional view of the active matrix light-emitting device in this embodiment. As shown in this figure, a TFT (Thin Film Transistor) 23 is formed on a substrate 22 of the light emitting device 21, and a first insulating film 24 for covering a step is further provided. An opening 25 is provided in the first insulating film 24, and the TFT 23 is electrically connected through the opening 25 to an anode 26 as a first electrode. In the figure, a gate insulating film and an interlayer insulating film constituting the TFT 23, wirings connected to the TFT 23, storage capacitors, and the like are omitted.

  In FIG. 6, the anode 26 is provided above the TFT 23, and is not provided on the first insulating film 24 without the TFT 23. A second insulating film 27 for protecting the end face of the anode 26 is provided on the anode 26.

  In the first embodiment and the second embodiment, the organic layer is provided only on the anode and the second insulating film. On the other hand, in this embodiment, the organic layer 28 is provided on the first insulating film 24 so as to cover the anode 26 and the second insulating film 27. On the other hand, the cathode 29 as the second electrode is provided on the portion of the organic layer 28 facing the anode 26, and on the portion of the organic layer 28 where the first insulating film 24 and the organic layer 28 are in contact with each other. Not provided. The anode 26, the organic layer 28, and the cathode 29 constitute an organic LED element as a light emitting element.

  In the present embodiment, the substrate 22, the first insulating film 24, the second insulating film 27, and the organic layer 29 are each made of a material that transmits light. The cathode 29 is made of a material that is transmissive to light, and the anode 26 is made of a material that reflects light such as metal. Thereby, the light emitted from the organic layer 28 and emitted to the cathode side passes through the cathode 29 and is extracted outside. On the other hand, the light emitted to the anode side is reflected by the anode 26 and travels toward the cathode side, and then passes through the cathode 29 and is extracted to the outside.

  As described above, in the light emitting device of this embodiment, similarly to Embodiment 1, light emitted from the organic layer is extracted outside only from the surface on the cathode side. Therefore, if the cathode side is the viewer side, light emission occurs only on the viewer side surface and does not occur on the back surface of the light emitting device. Therefore, according to the light emitting device of the present embodiment, it is possible to solve the problem that the light emitted to the back surface becomes stray light and the visibility is lowered. Note that the light extraction efficiency to the viewer side can be improved by optimizing the type and configuration of the members constituting the light emitting device.

  In the present embodiment, the cathode 29 may be either transparent or translucent. When translucent, the light interference effect increases, and this can be used to increase the light extraction efficiency to the viewer. In addition, ITO generally used as a transparent electrode needs to be formed by sputtering, but as a semitransparent electrode, for example, when a thin film (film thickness of about 5 nm to 15 nm) such as MgAg or Al is used, Film formation by vapor deposition is possible. According to the vapor deposition method, damage to the organic layer can be reduced as compared with the sputtering method, which is advantageous in terms of improving element characteristics and reliability. On the other hand, when a semi-transparent electrode is used, the angle dependency of the emission color increases. Therefore, it is preferable to decide whether to select transparent or translucent depending on the application.

  In the present invention, the first electrode may be a cathode and the second electrode may be an anode. That is, the cathode may be a reflective electrode and the anode may be a transparent electrode or a semitransparent electrode. Even in this case, if the anode side is set as the viewer side and the cathode side is set as the back side of the light emitting device, no light is emitted to the back side. it can.

On the other hand, light incident on the light emitting device from the outside is transmitted through the light emitting device other than the portion where a material that reflects light, such as a TFT or an electrode, is used. For example, in FIG. 6, the light incident on the light emitting device 21 passes through a portion (region X ₃ ) other than the portion where the TFT 23 and the anode 26 are provided. In contrast, region Y ₃ in FIG. 6, while forming the light emitting portion, an opaque portion for the incident light from the outside.

Region X ₃ is (not shown) a gate insulating film on the substrate 22, an interlayer insulating film (not shown), portion where the first insulating film 24 Oyohi organic layer 28 is provided (area a ₃₎ A portion (region b ₃ ) in which a second insulating film 27 is further provided between the first insulating film 24 and the organic layer 28, and a cathode 29 further on the organic layer 28 in the configuration of the region b _3. Are roughly divided into regions (region c ₃ ). Among these, the area a ₃ has the largest occupation area, and the area a ₃ is a portion where the organic layer 28 is formed on the insulating film 24 between the organic LED elements.

In this embodiment, the portion through which light is transmitted are mainly region a _3. Therefore, the transmittance of incident light can be increased as compared with the conventional example that must transmit all of the structures constituting the light emitting section. On the other hand, the region a ₁ in the first embodiment, since the area a ₃ has a configuration in which further organic layer is applied, the transmittance of incident light as compared to the first embodiment may be reduced slightly . However, according to the configuration of the present embodiment, it is not necessary to perform fine patterning on the organic layer, so that productivity can be improved as compared with the first embodiment.

  Note that the present embodiment is not limited to the example of FIG. 6, and various modifications can be made without departing from the spirit of the present invention.

  FIG. 7 shows a modification of the present embodiment. In FIG. 7, the parts denoted by the same reference numerals as those in FIG. 6 are the same.

  The configuration in FIG. 7 is basically the same as the configuration in FIG. 6, but in FIG. 6, the light emitted from the organic layer is one color, whereas in FIG. 7, the organic layers 28 R, 28 G, and 28 B are used. Are different in that they are red, green and blue, respectively. In addition, the combination of the color which light-emits by an organic layer may be other than this.

  As described above, according to the present embodiment, the light emitted from the organic layer is extracted to the outside only from either one of the cathode side and the anode side. Therefore, if the light emitting surface is on the viewer side, light emission from the back surface is eliminated, so that the problem of reduced visibility due to light emitted to the back surface can be solved. In addition, light incident from the outside mainly passes through a portion where only the insulating film and the organic layer are provided on the substrate, so that the transmittance of incident light can be made higher than before.

Embodiment 4 FIG.
FIG. 8 is a partial cross-sectional view of the active matrix light-emitting device in this embodiment. As shown in this figure, a TFT (Thin Film Transistor) 33 is formed on a substrate 32 of the light emitting device 31, and a first insulating film 34 for covering a step is further provided. An opening 35 is provided in the first insulating film 34, and the TFT 33 is electrically connected to the anode 36 as the first electrode through the opening 35. In the figure, the gate insulating film and the interlayer insulating film constituting the TFT 33, the wiring connected to the TFT 33, the storage capacitor, and the like are omitted.

  In FIG. 8, the anode 36 is provided above the TFT 33 and is not provided on the first insulating film 34 without the TFT 33. Further, a second insulating film 37 for protecting the end face of the anode 36 is provided on the anode 36. As in the third embodiment, the organic layer 38 is provided on the first insulating film 34 so as to cover the anode 36 and the second insulating film 37. The anode 36, the organic layer 38, and the cathode 39 constitute an organic LED element as a light emitting element.

  In the present embodiment, the cathode 39 as the second electrode has a two-layer structure of a translucent electrode 39a and a transparent electrode 39b. That is, as shown in FIG. 8, a translucent electrode 39a is provided on the organic layer 38 at a portion facing the anode 36, and the translucent electrode 39a is covered so as to be transparent on the organic layer 38. An electrode 39b is provided. The translucent electrode 39a is not provided on the portion of the organic layer 38 where the first insulating film 34 and the organic layer 38 are in contact with each other. In this portion, the transparent electrode 39b is formed directly on the organic layer 38. Is provided.

  When the cathode is a semi-transparent electrode, it is possible to form an electrode using a vapor deposition method, so that it is not necessary to give a large damage to the organic layer. However, the resistance value tends to be larger than that of a transparent electrode such as ITO formed by sputtering. Therefore, in order to obtain a desired resistance value while reducing damage to the organic layer, a two-layer structure in which a transparent electrode is provided on a semitransparent electrode is preferable. In this case, even if the transparent electrode is formed by sputtering, the translucent electrode provided on the organic layer functions as a barrier film, so that damage to the organic layer is reduced. Therefore, an element having excellent electrical characteristics and reliability can be obtained.

  In the present embodiment, the substrate 32, the first insulating film 34, the second insulating film 37, and the organic layer 38 are each made of a material that transmits light. The anode 36 is made of a material that reflects light such as metal. As described above, the cathode 39 is composed of the translucent electrode 39a and the transparent electrode 39b, and thus transmits light. Therefore, the light emitted from the organic layer 38 and emitted to the cathode side is transmitted through the cathode 39 and extracted outside. On the other hand, the light emitted to the anode side is reflected by the anode 36 and travels toward the cathode side, and then passes through the cathode 39 and is extracted to the outside.

  As described above, in the light emitting device of this embodiment, similarly to Embodiment 1, light emitted from the organic layer is extracted outside only from the surface on the cathode side. Therefore, if the cathode side is the viewer side, light emission occurs only on the viewer side surface and does not occur on the back surface of the light emitting device. Therefore, according to the light emitting device of the present embodiment, it is possible to solve the problem that the light emitted to the back surface becomes stray light and the visibility is lowered. Note that the light extraction efficiency to the viewer side can be improved by optimizing the type and configuration of the members constituting the light emitting device.

  In the present invention, the first electrode may be a cathode and the second electrode may be an anode. That is, a material that reflects light may be used for the cathode, and the anode may have a two-layer structure of a translucent electrode and a transparent electrode. Even in this case, if the anode side is set as the viewer side and the cathode side is set as the back side of the light emitting device, no light is emitted to the back side. it can.

On the other hand, light incident on the light emitting device from the outside is transmitted through the light emitting device other than the portion where a material that reflects light, such as a TFT or an electrode, is used. For example, in FIG. 8, light incident on the light emitting device 31 is transmitted through a portion (region X ₄ ) other than the portion where the TFT 33 and the anode 36 are provided. In contrast, region Y ₄ in FIG. 8, while constituting the light emitting portion, an opaque portion for the incident light from the outside.

Region X ₄ is (not shown) a gate insulating film on a substrate 32, an interlayer insulating film (not shown), the first insulating film 34, the portion where the organic layer 38 and the transparent electrode 39b is provided (area a ₄ ), a portion where the second insulating film 37 is further provided between the first insulating film 34 and the organic layer 38 (region b ₄ ), and the organic layer 38 and the transparent electrode 39b in the configuration of the region b _4. And a portion (region c ₄ ) in which a semitransparent electrode 39a is further provided. Of these, an area a ₄ is the largest occupying area, area a ₄ is a portion organic layer 38 and the transparent electrode 39b is formed in contact with each other on the insulating film 34 between the organic LED element.

In this embodiment, the portion through which light is transmitted are mainly areas a _4. Therefore, the transmittance of incident light can be increased as compared with the conventional example that must transmit all of the structures constituting the light emitting section. On the other hand, the region a ₁ in the first embodiment, since the area a ₄ has a configuration in which applied further organic layer and the translucent electrode, slightly decreases the transmittance of the incident light as compared with the first embodiment There is a risk. However, according to the configuration of the present embodiment, it is not necessary to perform fine patterning on the organic layer, so that productivity can be improved as compared with the first embodiment. In addition, since the viewer-side electrode has a two-layer structure of a translucent electrode and a transparent electrode, an element having excellent electrical characteristics and reliability can be obtained.

  As described above, according to the present embodiment, the light emitted from the organic layer is extracted to the outside only from either one of the cathode side and the anode side. Therefore, if the light emitting surface is on the viewer side, light emission from the back surface is eliminated, so that the problem of reduced visibility due to light emitted to the back surface can be solved. In addition, since the number of structures to which light incident from the outside must be transmitted is smaller than that of the conventional structure, the transmittance of incident light can be made higher than that of the conventional structure.

Embodiment 5. FIG.
FIG. 9 is a partial cross-sectional view of the active matrix light-emitting device in this embodiment. As shown in this figure, a TFT (Thin Film Transistor) 43 is formed on a substrate 42 of the light emitting device 41, and further, a first insulating film 44 for covering a step is provided. In addition, an opening 45 is provided in the first insulating film 44, and the TFT 43 is electrically connected to the anode 46 as the first electrode through the opening 45. In the figure, a gate insulating film and an interlayer insulating film constituting the TFT 43, wirings connected to the TFT 43, storage capacitors, and the like are omitted.

  In FIG. 9, the anode 46 is provided above the TFT 43 and is not provided on the first insulating film 44 without the TFT 43. Further, a second insulating film 47 for protecting the end face of the anode 46 is provided on the anode 46. An organic layer 48 is provided on the anode 46 and the second insulating film 47, and a semitransparent electrode 49 a is further provided on the organic layer 48. The anode 46, the organic layer 48, and the cathode 49 constitute an organic LED element as a light emitting element.

  Also in the present embodiment, as in the fourth embodiment, the cathode 49 as the second electrode has a two-layer structure of a translucent electrode 49a and a transparent electrode 49b. That is, as shown in FIG. 9, a semitransparent electrode 49a is provided on a portion of the organic layer 48 facing the anode 46, and the first insulating film 44 is covered with the semitransparent electrode 49a. A transparent electrode 49b is provided on the top.

  When the cathode is a semi-transparent electrode, it is possible to form an electrode using a vapor deposition method, so that it is not necessary to give a large damage to the organic layer. However, the resistance value tends to be larger than that of a transparent electrode such as ITO formed by sputtering. Therefore, in order to obtain a desired resistance value while reducing damage to the organic layer, a two-layer structure in which a transparent electrode is provided on a semitransparent electrode is preferable. In this case, even if the transparent electrode is formed by sputtering, the translucent electrode provided on the organic layer functions as a barrier film, so that damage to the organic layer is reduced. Therefore, an element having excellent electrical characteristics and reliability can be obtained.

  In the present embodiment, the substrate 42, the first insulating film 44, the second insulating film 47, and the organic layer 48 are each made of a material that transmits light. The anode 46 is made of a material that reflects light such as metal. As described above, the cathode 49 is composed of the translucent electrode 49a and the transparent electrode 49b, and thus transmits light. Therefore, the light emitted from the organic layer 48 and emitted to the cathode side passes through the cathode 49 and is extracted outside. On the other hand, the light emitted to the anode side is reflected by the anode 46 and travels toward the cathode side, and then passes through the cathode 49 and is extracted to the outside.

  As described above, in the light emitting device of this embodiment, similarly to Embodiment 1, light emitted from the organic layer is extracted outside only from the surface on the cathode side. Therefore, if the cathode side is the viewer side, light emission occurs only on the viewer side surface and does not occur on the back surface of the light emitting device. Therefore, according to the light emitting device of the present embodiment, it is possible to solve the problem that the light emitted to the back surface becomes stray light and the visibility is lowered. Note that the light extraction efficiency to the viewer side can be improved by optimizing the type and configuration of the members constituting the light emitting device.

  In the present invention, the first electrode may be a cathode and the second electrode may be an anode. That is, a material that reflects light may be used for the cathode, and the anode may have a two-layer structure of a translucent electrode and a transparent electrode. Even in this case, if the anode side is set as the viewer side and the cathode side is set as the back side of the light emitting device, no light is emitted to the back side. it can.

On the other hand, light incident on the light emitting device from the outside is transmitted through the light emitting device other than the portion where a material that reflects light, such as a TFT or an electrode, is used. For example, in FIG. 9, light incident on the light emitting device 41 is transmitted through a portion (region X ₅ ) other than the portion where the TFT 43 and the anode 46 are provided. In contrast, region Y ₅ in FIG. 9, while constituting the light emitting portion, an opaque portion for the incident light from the outside.

Region X ₅ is (not shown) a gate insulating film on the substrate 42, an interlayer insulating film (not shown), a portion where the first insulating film 44 and the transparent electrode 49b is provided (the region a _5), A portion (region b ₅ ) in which a second insulating film 47 is further provided between the first insulating film 44 and the transparent electrode 49b, and the second insulating film 47 and the transparent electrode 49b in the configuration of the region b ₅ . Further, it is roughly divided into a portion (region c ₅ ) where an organic layer 48 and a semitransparent electrode 49b are provided. Of these, a region a ₅ is the largest occupying area, region a ₅ is a portion transparent electrode 49b is formed on the insulating film 44 between the organic LED element.

In this embodiment, the portion through which light is transmitted are mainly region a _5. Therefore, the transmittance of incident light can be increased as compared with the conventional example that must transmit all of the structures constituting the light emitting section. On the other hand, the region a ₁ in the first embodiment, since the area a ₅ has a structure in which joined more transparent electrodes, the transmittance of incident light as compared to the first embodiment may be reduced slightly . However, according to the configuration of the present embodiment, the electrode on the viewer side has a two-layer structure of a translucent electrode and a transparent electrode, whereby an element having excellent electrical characteristics and reliability can be obtained.

  As described above, according to the present embodiment, the light emitted from the organic layer is extracted to the outside only from either one of the cathode side and the anode side. Therefore, if the light emitting surface is on the viewer side, light emission from the back surface is eliminated, so that the problem of reduced visibility due to light emitted to the back surface can be solved. In addition, since the number of structures to which light incident from the outside must be transmitted is smaller than that of the conventional structure, the transmittance of incident light can be made higher than that of the conventional structure.

Embodiment 6 FIG.
FIG. 10 is a partial cross-sectional view of the segment type light-emitting device in the present embodiment. As shown in this figure, an anode 53 as a first electrode is formed on a substrate 52 of the light emitting device 51, and an insulating film 54 for element isolation is formed between the anodes 53. 53 is provided so as to cover the edge of 53. An organic layer 55 is provided on the insulating film 54 and the anode 53. The anode 53, the organic layer 55, and the cathode 56 constitute an organic LED element as a light emitting element. One pixel is constituted by one of the anodes 53, one of the cathodes 56 provided at positions corresponding thereto, and the organic layer 55 sandwiched therebetween.

  In the present embodiment, it is preferable to make the width of the cathode 56 as the second electrode narrower than before from the viewpoint of improving the transmittance. Specifically, the width of the cathode 53 is preferably about 20% to 40% of the pixel pitch. For example, the width can be set to about 1/4 with respect to a conventional one having the same specification.

  The substrate 52, the insulating film 54, the anode 53, and the organic layer 55 are all made of a transparent material. On the other hand, the cathode 56 is made of a material that reflects light such as metal. Thereby, the light emitted from the organic layer 55 and emitted to the anode side passes through the anode 53 and is extracted to the outside. On the other hand, the light emitted to the cathode side is reflected by the cathode 56 and travels toward the anode side, then passes through the anode 53 and is extracted outside.

  Thus, in the light emitting device of this embodiment, light emitted from the organic layer is extracted outside only from the surface on the anode side. Therefore, if the anode side is the viewer side, light emission occurs only on the viewer side surface, so that the problem that the light emitted to the back surface becomes stray light and the visibility is lowered can be solved. Note that the light extraction efficiency to the viewer side can be improved by optimizing the type and configuration of the members constituting the light emitting device.

  In the present invention, the first electrode may be a cathode and the second electrode may be an anode. That is, the anode can be a reflective electrode and the cathode can be a transparent electrode. Even in this case, if the cathode side is set as the viewer side and the anode side is set as the back side of the light emitting device, no light is emitted to the back side. it can.

On the other hand, light incident on the light emitting device from the outside passes through a portion other than a portion where a material that reflects light is used. For example, in FIG. 10, the light incident on the light emitting device 51 is transmitted through a portion (region X ₆ ) where the cathode 56 is not provided. Region X ₆ may also be called a part organic layer 55 is exposed between the cathode 56. In contrast, region Y ₆ in FIG. 10, while forming the light emitting portion, an opaque portion for the incident light from the outside.

  FIG. 11 is an example of a partial plan view of the light-emitting device of FIG. Note that a sectional view taken along the line AA ′ in FIG. 11 corresponds to FIG. 10.

11, region _{Y 6} is, on the substrate 52 in FIG. 10, an anode 53, a portion of the organic layer 55 and a cathode 56 are provided. That is, the region Y _6, while corresponding to the light-emitting portion, an opaque portion for the incident light from the outside. In contrast, region _{X 6} is comprised of regions _{a 6} and a region _{b 6.} Here, the region a ₆ is a portion where the anode 53 and the organic layer 55 are formed on the substrate 52. The region b ₆ is a portion where the insulating film 54 and the organic layer 55 are formed on the substrate 52. That is, in the region X _6, since the cathode 56 which reflects light is not provided, this region is a portion transparent to light incident from the outside.

  As described with reference to FIG. 13, in the conventional light emitting device, both the light emitting portion and the non-light emitting portion are light transmitting portions. In this structure, since the cathode 206 is also provided in the non-light emitting portion, light must pass through the cathode 206 in addition to the substrate 202, the anode 203, the insulating film 204, and the organic layer 205, and the transmittance is constant. There was a limit to exceeding the value.

  However, according to the present embodiment, the light incident from the outside passes through the portion where the cathode is not provided, so that the transmittance can be increased as compared with the conventional case. Since the light emitting part does not transmit light, the area of the light transmitting part is smaller in the embodiment than in the conventional product in which both the light emitting part and the non-light emitting part transmit light. As described above, this can be dealt with by making the width of the cathode narrower than before.

  As described above, according to the present embodiment, the light emitted from the organic layer is extracted to the outside only from either one of the cathode side and the anode side. Therefore, if the light emitting surface is on the viewer side, light emission from the back surface is eliminated, so that the problem of reduced visibility due to light emitted to the back surface can be solved.

  In addition, according to the present embodiment, the light incident from the outside passes through the portion where the cathode is not provided, so that the transmittance of the incident light can be made higher than before. When the cathode is a reflective electrode, a metal such as Al (aluminum) can be used, so that the resistance can be reduced.

  Furthermore, since the light emitting device of this embodiment can take advantage of the conventional bottom emission type element configuration and process, the characteristics and lifetime of the element are improved as compared with the case where a transparent element is newly developed. This is advantageous.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in Embodiments 1 to 6, an organic LED element is used as a light emitting element, but an inorganic LED element may be used in the present invention. Further, the present invention can be applied to other reflective light emitting devices.

  In addition, the active matrix light-emitting devices of Embodiments 1 to 5 are top emission types in which light is emitted above the substrate, but the present invention is a bottom emission type in which light is emitted below the substrate. There may be. Similarly, although the segment type light emitting device of the sixth embodiment is the bottom emission type, the present invention may be a top emission type segment type light emitting device.

3 is an example of a cross-sectional view of the light-emitting device in Embodiment 1. FIG. 3 is an example of a plan view of the light-emitting device in Embodiment 1. FIG. 6 is another example of a plan view of the light emitting device in Embodiment 1. FIG. 6 is another example of a cross-sectional view of the light-emitting device in Embodiment 1. FIG. FIG. 6 is a cross-sectional view of a light-emitting device in Embodiment 2. 6 is an example of a cross-sectional view of a light-emitting device in Embodiment 3. FIG. 12 is another example of a cross-sectional view of the light-emitting device in Embodiment 3. FIG. 7 is a cross-sectional view of a light-emitting device in Embodiment 4. FIG. 7 is a cross-sectional view of a light-emitting device in Embodiment 5. FIG. FIG. 10 is a cross-sectional view of a light-emitting device in Embodiment 6. It is a top view of the light-emitting device of FIG. It is sectional drawing of the conventional active matrix type organic LED light-emitting device. It is sectional drawing of the conventional segment type organic LED light-emitting device.

Explanation of symbols

1, 11, 21, 31, 41, 51 Light-emitting device 2, 12, 22, 32, 42, 52, 102, 202 Substrate 3, 13, 23, 33, 43, 103 TFT
4, 14, 24, 34, 44, 104 First insulating film 5, 15, 25, 35, 45, 105 Opening 6, 16, 26, 36, 46, 53, 106, 203 Anode 7, 17, 27 , 37, 47, 107 Second insulating film 54, 204 Insulating film 8, 18, 28, 38, 48, 55, 108, 205 Organic layer 9, 19, 29, 39, 49, 56, 109, 206 Cathode

Claims (8)

A plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
There is a portion where the insulating film is exposed between the light emitting elements, and light incident from the outside mainly transmits through this portion. A plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
There is a portion where the insulating film is removed between the light emitting elements, and light incident from the outside mainly transmits through this portion. A plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
Between the light emitting elements, there is a portion where the light emitting layer is formed on the insulating film, and light incident from the outside mainly transmits through this portion. A plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
The second electrode has a structure in which a semitransparent electrode and a transparent electrode are laminated in order from the light emitting layer side,
Between the light emitting elements, there is a portion where the light emitting layer and the transparent electrode are formed in contact with each other on the insulating film, and light incident from the outside mainly transmits through this portion. apparatus. A plurality of thin film transistors provided on a substrate;
An insulating film provided on the substrate and covering the thin film transistor;
A light emitting layer is sandwiched between a first electrode that reflects light and a second electrode that transmits light, and the first thin film transistor is connected to the thin film transistor through an opening provided in the insulating film. A light-emitting device comprising a plurality of light-emitting elements to which electrodes are electrically connected,
The second electrode has a structure in which a semitransparent electrode and a transparent electrode are laminated in order from the light emitting layer side,
Between the light emitting elements, there is a portion where the transparent electrode is formed on the insulating film, and light incident from the outside mainly transmits through this portion. A plurality of first electrodes provided on the substrate and transmitting light;
An insulating film provided between the first electrodes;
A light emitting layer provided on the first electrode and the insulating film;
A light emitting device including a plurality of second electrodes provided on the light emitting layer and reflecting light,
There is a portion where the light emitting layer is exposed between the second electrodes, and light incident from the outside is mainly transmitted through this portion. A pixel comprising one of the first electrodes, one of the second electrodes provided at a position corresponding to the first electrode, and the light emitting layer sandwiched between the first electrode and the second electrode Has a structure in which a plurality of are arranged,
The light emitting device according to claim 6, wherein the width of the second electrode is in a range of 20% to 40% of the pitch of the pixels. The light emitting device according to claim 1, wherein the light emitting element is an organic LED element.

Images