WO2014080512A1 - Light emitting device and method for producing light emitting device - Google Patents

Abstract

This light emitting device (100) comprises an optical-path changing layer (120). The optical-path changing layer (120) includes an optical-path changing region (121) and a base region (122) other than the optical-path changing region (121), and is arranged between a light-transmissive substrate (110) and a second electrode (150). The difference in refractive index between the optical-path changing region (121) and the base region (122) increases with the increase in distance from the boundary between the optical-path changing region (121) and the base region (122) toward the inside of the optical-path changing region (121). The optical-path changing region (121) changes the optical path of light in the course of letting the light pass therethrough.

Description

LIGHT EMITTING DEVICE AND LIGHT EMITTING DEVICE MANUFACTURING METHOD

The present invention relates to a light emitting device having an organic light emitting layer and a method for manufacturing the light emitting device.

There is a light emitting device having an organic light emitting layer as one of the light emitting devices. In this light emitting device, it is desired to improve the ratio of light emitted to the outside (light extraction efficiency) of the light generated in the organic light emitting layer.

As a technique for improving the light extraction efficiency, there is one described in Patent Document 1. The organic EL element described in Patent Document 1 includes an organic thin film layer, a pair of electrodes, one of which is a transparent electrode, sandwiching the organic thin film layer, a high refractive index layer having a higher refractive index than the organic thin film layer, and a medium And a layer in contact with a high refractive index layer in which microspheres having different refractive indexes are dispersed. Patent Document 1 describes that the light extraction efficiency is improved by providing a periodic structure in which microspheres are dispersed in a medium. Specifically, the microspheres consists SiO _2, the layer in contact with the high refractive index layer, a titanium oxide layer formed by dispersing the microspheres, also made of titanium oxide layer a high refractive index layer.

JP 2004-14530 A

The inventor considered that the technique described in Patent Document 1 has the following problems.
In the technique of Patent Document 1, since microspheres having a refractive index different from that of the medium are dispersed in the medium, the refractive index changes sharply at the interface between the microsphere and the medium. For this reason, if there is no microsphere, light that is originally extracted from the organic EL element may be reflected at the interface between the microsphere and the medium, thereby changing the optical path in a direction different from the extraction direction. There is. Therefore, the technique of Patent Document 1 has room for improvement regarding light extraction efficiency.

An example of a problem to be solved by the present invention is to improve the light extraction efficiency of the light emitting device.

The invention according to claim 1 is a translucent substrate;
A translucent first electrode disposed on one surface side of the translucent substrate;
A second electrode disposed on the opposite side of the translucent substrate with respect to the first electrode;
An organic functional layer including at least a light-emitting layer and disposed between the first electrode and the second electrode;
An optical path changing region that changes an optical path of the light in the process of transmitting light; and a base region other than the optical path changing region, and is disposed between the translucent substrate and the second electrode. An optical path changing layer,
With
The difference in refractive index between the optical path changing region and the base region is a light emitting device that increases as the distance from the boundary between the optical path changing region and the base region increases inward of the optical path changing region.

According to a twelfth aspect of the present invention, a step of forming a light-transmitting first electrode on one surface side of the light-transmitting substrate;
Forming an organic functional layer including at least a light emitting layer on a side opposite to the light-transmitting substrate with respect to the first electrode;
Forming a second electrode on the side opposite to the first electrode with respect to the organic functional layer;
An optical path changing layer including an optical path changing area for changing an optical path of the light in the process of transmitting light, and a base area other than the optical path changing area, the light-transmitting substrate, the second electrode, Forming between, and
With
In the step of forming the optical path changing layer, a difference in refractive index between the optical path changing area and the base area increases as the distance from the boundary between the optical path changing area and the base area increases inward of the optical path changing area. And a method of manufacturing a light emitting device for forming the optical path changing layer.

The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following drawings attached thereto.

It is sectional drawing which shows the structure of the light-emitting device which concerns on 1st Embodiment. It is a figure which shows the example of the change characteristic of the refractive index from an optical path change layer to a translucent board | substrate. It is principal part sectional drawing which shows the example of operation | movement of the light-emitting device which concerns on 1st Embodiment. It is sectional drawing which shows the one part process of the manufacturing method of the light-emitting device which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the light-emitting device which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the light-emitting device which concerns on 3rd Embodiment. It is a figure which shows the example of the change characteristic of the refractive index from the optical path change layer of the light-emitting device which concerns on 4th Embodiment to the translucent board | substrate. It is principal part sectional drawing which shows the example of operation | movement of the light-emitting device which concerns on 4th Embodiment. FIG. 9A is a plan view showing the configuration of the light emitting device according to Example 1, and FIG. 9B is a cross-sectional view taken along the line BB in FIG. 9A. It is sectional drawing which shows the modification 1 of an organic functional layer. It is sectional drawing which shows the modification 2 of an organic functional layer.

Hereinafter, embodiments will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

(First embodiment)
FIG. 1 is a cross-sectional view illustrating a configuration of a light emitting device 100 according to the embodiment. The light emitting device 100 includes an organic EL (Electro Luminescence) element. The light emitting device 100 can be used as a light source of, for example, a display, a lighting device, or an optical communication device.

The light emitting device 100 according to the present embodiment includes a translucent substrate 110, an optical path changing layer 120, a first electrode 130, an organic functional layer 140, and a second electrode 150. The first electrode 130 is translucent. The second electrode 150 is disposed on the opposite side of the translucent substrate 110 with respect to the first electrode 130. The organic functional layer 140 includes at least a light emitting layer. The organic functional layer 140 is disposed between the first electrode 130 and the second electrode 150. The optical path changing layer 120 includes an optical path changing area 121 and a base area 122. The optical path changing area 121 changes the optical path of the light in the process of transmitting the light. The base region 122 is a region other than the optical path changing region 121 in the optical path changing layer 120. The optical path changing layer 120 is disposed between the translucent substrate 110 and the second electrode 150. The refractive index difference between the optical path changing area 121 and the base area 122 increases as the distance from the boundary between the optical path changing area 121 and the base area 122 increases inward.

Hereinafter, in order to simplify the description, description will be made assuming that the positional relationship (vertical relationship, etc.) of each component of the light emitting device 100 is the relationship shown in each drawing. However, the positional relationship in this description is irrelevant to the positional relationship when the light emitting device 100 is used.

The translucent substrate 110 is a plate-like member made of a translucent material such as glass or resin. For example, the upper surface of the translucent substrate 110, that is, the surface of the translucent substrate 110 opposite to the organic functional layer 140 is a flat light extraction surface. This light extraction surface is in contact with air (refractive index 1) filling the light emission space. In addition, the light extraction film is affixed on the upper surface of the translucent board | substrate 110, and the upper surface of this light extraction film may comprise the light extraction surface.

The first electrode 130 may be a transparent electrode made of a metal oxide conductor such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). However, the first electrode 130 may be a metal thin film that is thin enough to transmit light.

The second electrode 150 is a reflective electrode made of a metal film such as Al. The second electrode 150 reflects light traveling from the organic functional layer 140 toward the second electrode 150 toward the translucent substrate 110.

When a voltage is applied between the first electrode 130 and the second electrode 150, the light emitting layer of the organic functional layer 140 emits light. The first electrode 130, the base region 122 of the optical path changing layer 120, the optical path changing region 121 of the optical path changing layer 120, the translucent substrate 110, and the organic functional layer 140 all emit light from the organic functional layer 140. Transmits at least part of the light. Part of the light emitted from the light emitting layer is emitted (extracted) from the light extraction surface of the light-transmitting substrate 110 to the outside of the light emitting device 100 (that is, the light emission space).

For example, in the optical path changing layer 120, all areas other than the optical path changing area 121 are the base area 122. However, the optical path changing layer 120 may be configured to include other areas of the optical path changing area 121 and the base area 122.

In the optical path changing layer 120, one optical path changing area 121 exists. Alternatively, the optical path changing layer 120 has a plurality of optical path changing areas 121 in a random arrangement.

As described above, the refractive index difference between the optical path changing area 121 and the base area 122 increases as the distance from the boundary between the optical path changing area 121 and the base area 122 increases inward. That is, the refractive index of the optical path changing region 121 is reduced or increased as it moves away from the boundary between the optical path changing region 121 and the base region 122 inward of the optical path changing region 121. Here, it is preferable that the refractive index difference monotonously increases as the distance from the boundary between the optical path changing region 121 and the base region 122 increases. However, it is sufficient that an increasing tendency is recognized as a whole in the direction away from the boundary between the optical path changing region 121 and the base region 122, and for example, it may be decreased in a part of the section.

The refractive index of the optical path changing area 121 is preferably the same as the refractive index of the base area 122 at the boundary between the optical path changing area 121 and the base area 122.

It is preferable that the refractive index difference between the optical path changing area 121 and the base area 122 gradually increases as the distance from the boundary between the optical path changing area 121 and the base area 122 increases inward. That is, it is preferable that there is no portion where the refractive index difference increases discontinuously.

The dimension d of the optical path changing region 121 is preferably equal to or longer than the emission wavelength from the light emitting layer of the organic functional layer 140. The peak wavelength of the emission wavelength is, for example, in the visible light region. Therefore, the dimension d is, for example, at least (360 nm / average refractive index of the optical path changing layer 120) or more, and preferably at least (400 nm / average refractive index of the optical path changing layer 120). However, it is preferable that the dimension d is sufficiently larger than the emission wavelength from the light emitting layer. Therefore, for example, when the refractive index of the optical path changing layer 120 is 1.8, if the dimension d is determined for each of the individual emission color regions, the dimension d is 200 nm or more for blue and 311 nm for green. As mentioned above, it is more preferable to set it as 356 nm or more about red, and 356 nm or more about white.

For example, the shape of the optical path changing region 121 is at least a part of a sphere having a diameter equal to or larger than the emission wavelength from the light emitting layer. That is, the outer shape of the optical path changing region 121 includes at least a part of a spherical outer peripheral surface having a diameter equal to or larger than the emission wavelength from the light emitting layer. For example, the outer shape of the optical path changing region 121 includes a curved surface that is convex toward the second electrode 150 side. For example, as shown in FIG. 1, the optical path changing region 121 includes a spherical lower half having a diameter equal to or larger than the emission wavelength from the light emitting layer, and is directed toward the second electrode 150 (downward in FIG. 1). Includes convex curved surfaces.

1 shows an example in which the optical path changing region 121 is exposed on the end surface (upper surface in FIG. 1) of the optical path changing layer 120 on the light transmitting substrate 110 side, the optical path changing region 121 is on the end surface. It does not have to be exposed. That is, a part of the base region 122 may exist between the end surface of the light path changing layer 120 on the light transmitting substrate 110 side and the light path changing region 121. Further, in FIG. 1, the optical path changing area 121 having a shape in which the upper part of the sphere is missing is illustrated, but the optical path changing area 121 may be spherical (entire).

In the case of the present embodiment, for example, the optical path changing region 121 includes a region having a refractive index smaller than that of the base region 122. For example, except for the boundary between the optical path changing area 121 and the base area 122, the refractive index of the optical path changing area 121 is smaller than the refractive index of the base area 122.

In the case of this embodiment, the optical path changing layer 120 is disposed between the translucent substrate 110 and the first electrode 130. In this case, the refractive index of the layer including the base region 122 and the optical path changing region 121 of the optical path changing layer 120 is preferably not less than the refractive index of the translucent substrate 110 and not more than 2.0, for example. More preferably, the refractive index of the optical path changing layer 120 is equal to the refractive index of the first electrode 130.

In addition, the refractive index of the layer including the base region 122 and the optical path changing region 121 of the optical path changing layer 120 can be set to be equal to or higher than the refractive index of the organic functional layer 140, for example. The optical path changing layer 120 is made of a dielectric, for example. The material of the optical path changing layer 120 can be the same as the material of the organic functional layer 140, for example. The refractive index of the organic functional layer 140 is, for example, about 1.6 or more and 2.0 or less.

The optical path changing area 121 is formed, for example, by heating a part of the optical path changing layer 120 (base area 122). Therefore, as the material of the optical path changing layer 120, for example, a material whose refractive index is lowered by heating can be used. That is, the material of the optical path changing layer 120 can be a material having a refractive index higher than that of the organic functional layer 140 and having a low refractive index when heated. Examples of such materials include organic materials such as phthalocyanine used for DVDs or CDs. By heating a part of the optical path changing layer 120, the molecular structure is destroyed and the refractive index of the heated part is lowered.

For example, one surface (the lower surface in FIG. 1) of the translucent substrate 110 and one surface (the upper surface in FIG. 1) of the optical path changing layer 120 are in contact with each other. Further, the other surface (lower surface in FIG. 1) of the optical path changing layer 120 and one surface (upper surface in FIG. 1) of the first electrode 130 are in contact with each other. Further, the other surface (lower surface in FIG. 1) of the first electrode 130 and one surface (upper surface in FIG. 1) of the organic functional layer 140 are in contact with each other. Further, the other surface (lower surface in FIG. 1) of the organic functional layer 140 and one surface (upper surface in FIG. 1) of the second electrode 150 are in contact with each other. However, another layer may exist between the translucent substrate 110 and the optical path changing layer 120. Similarly, another layer may exist between the optical path changing layer 120 and the first electrode 130. Similarly, another layer may exist between the first electrode 130 and the organic functional layer 140. Similarly, another layer may exist between the organic functional layer 140 and the second electrode 150.

FIG. 2 is a diagram showing an example of the refractive index change characteristic from the optical path changing layer 120 to the translucent substrate 110. That is, FIG. 2 shows an example of the refractive index change characteristic from one end A1 to the other end A2 of the line segment A in FIG. For example, in the base region 122, the refractive index is constant regardless of the position (region R1 in FIG. 2). The refractive index of the boundary between the base region 122 and the optical path changing region 121 (the boundary between the region R1 and the region R2 in FIG. 2) is the same as the refractive index of the base region 122. In the optical path changing region 121, the refractive index gradually increases as the distance from the boundary between the optical path changing region 121 and the base region 122 increases, that is, toward the center of the above-described spherical shape (a spherical shape whose diameter is equal to or larger than the emission wavelength from the light emitting layer). Is reduced (region R2 in FIG. 2). Furthermore, the refractive index gradually increases again from the spherical center toward the light transmitting substrate 110 (region R3 in FIG. 2). As described above, the refractive index of the optical path changing region 121 is the same as the refractive index of the base region 122 at the boundary with the base region 122, and gradually decreases as the distance from the boundary increases. In addition, the refractive index of the translucent substrate 110 is smaller than the refractive index of the optical path changing layer 120 (region R4 in FIG. 2).

FIG. 3 is a cross-sectional view of a main part illustrating an example of the operation of the light emitting device 100 according to the first embodiment, and illustrates only the translucent substrate 110, the optical path changing layer 120, and the first electrode 130. When the refractive index of the optical path changing region 121 decreases as the distance from the base region 122 increases, for example, an operation as described below can be realized.

When the refractive index of the optical path changing layer 120 is sufficiently large (more than the refractive index of the translucent substrate 110), the light traveling obliquely upward in the first electrode 130 is incident on the optical path changing layer 120 as it is.

Suppose that this light travels in the order of the optical paths L11 and L12 shown in FIG. 3 when the optical path changing area 121 does not exist in the optical path changing layer 120. That is, the light travels obliquely upward in the optical path changing layer 120 (optical path L11), and then reflects at the interface between the optical path changing layer 120 and the translucent substrate 110 and travels diagonally downward (optical path L12). And

In the case of the present embodiment, since the optical path changing region 121 exists in the optical path changing layer 120, the optical path of this light gradually increases in the process of passing through the optical path changing region 121 as indicated by the optical path L1. Be changed. Thereby, the direction of this light can be changed to less than the critical angle at the interface between the optical path changing layer 120 and the translucent substrate 110, and this light can be incident from the optical path changing region 121 to the translucent substrate 110 side. Further, this light can be emitted from the translucent substrate 110 to the upper side thereof (that is, outside the light emitting device 100).

Next, an example of a method for manufacturing the light emitting device according to this embodiment will be described. FIG. 4 is a sectional view showing a part of the manufacturing method. This manufacturing method includes the following steps (1) to (4).
(1) Step of forming a transparent first electrode 130 on one surface side of the transparent substrate 110 (2) At least light emission on the opposite side of the transparent substrate 110 with respect to the first electrode 130 Step of forming organic functional layer 140 including layers (3) Step of forming second electrode 150 on the side opposite to first electrode 130 with respect to organic functional layer 140 (4) Transmitting light An optical path changing layer 120 including an optical path changing area 121 that changes the optical path of the light in the process and a base area 122 other than the optical path changing area 121 is formed between the translucent substrate 110 and the second electrode 150. Step of forming in between (FIGS. 4A and 4B)
In the step of forming the optical path changing layer 120, the refractive index difference between the optical path changing area 121 and the base area 122 increases as the distance from the boundary between the optical path changing area 121 and the base area 122 increases inward of the optical path changing area 121. Thus, the optical path changing layer 120 is formed.

Hereinafter, the manufacturing process will be described in order with reference to FIG. 1 and FIG.

First, an organic material such as NPB or phthalocyanine is vapor-deposited or applied on the lower surface of the translucent substrate 110 to form a portion that becomes the base region 122 in the optical path changing layer 120 (FIG. 4A). Note that the optical path changing region 121 is formed at an appropriate timing after the base region 122 is formed. The timing and method for forming the optical path changing region 121 will be described later.

Next, a light-transmitting conductive film made of a metal oxide conductor such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) is formed on the lower surface of the optical path changing layer 120 (base region 122) by sputtering or the like. A first electrode 130 is formed by patterning the film by etching.

Next, the organic functional layer 140 is formed by applying an organic material to the lower surface of the first electrode 130.

Next, a second electrode 150 is formed by depositing a metal material such as Al in a desired pattern on the lower surface of the organic functional layer 140 by vapor deposition using a mask or the like.

In addition, you may form a bus line and a partition (refer FIG. 9) at an appropriate timing as needed. Further, a sealing layer may be formed on the lower surface of the second electrode 150 as necessary.

Next, how to form the optical path changing region 121 will be described.

The optical path changing region 121 is formed by heating a part of the optical path changing layer 120 (base region 122) by irradiating light. Specifically, for example, by irradiating a part of the optical path changing layer 120 with laser light, a part of the optical path changing layer 120 can be heated to form the optical path changing area 121 (FIG. 4B). ). By heating a part of the optical path changing layer 120, the molecular structure of the material constituting the optical path changing layer 120 is changed, or the density distribution of the material constituting the optical path changing layer 120 is changed (in this embodiment, The refractive index of the portion decreases.

Here, the intensity distribution of the light (laser light or the like) irradiated by the above-described method is a Gaussian distribution, and the intensity of the central portion of the irradiation spot of the light is increased. For this reason, the closer to the center of the irradiation spot, the greater the influence on the molecular structure and density distribution of the material constituting the optical path changing layer 120. Therefore, for example, the refractive index of the optical path changing region 121 gradually decreases toward the center of the irradiation spot.

The timing for forming the optical path changing region 121 can be any timing after the optical path changing layer 120 (base region 122) is formed.

When forming the optical path changing region 121 after forming the optical path changing layer 120 (base region 122) and before forming the first electrode 130, light is irradiated from any surface side of the optical path changing layer 120 (base region 122). You may do it.
In addition, when the optical path changing region 121 is formed after the formation of the first electrode 130 and before the formation of the organic functional layer 140, in order to suppress efficient light irradiation and damage to the first electrode 130 due to concentrated light. Further, light is irradiated from the side of the transparent substrate 110 close to the processing point.
In any of these cases, the organic functional layer 140 has not yet been formed. For this reason, since it is not necessary to consider the damage to the organic functional layer 140, either a CW laser (continuous wave oscillation operation laser) or a pulse laser may be used.

Further, after the formation of the organic functional layer 140 and the second electrode 150, the optical path changing region 121 may be formed after the sealing is completed and the light emitting device 100 having the panel structure is constructed. In this case, light is irradiated from the translucent substrate 110 side. In this case, in order to use a CW laser or a pulse laser, it is preferable to consider that heat is not applied to the organic functional layer 140 as much as possible. Alternatively, a femtosecond laser or a nanosecond laser may be used.

The large-area optical path changing area 121 may be formed by irradiating the laser once, or the small area is irradiated in a plurality of times, and the large-area optical path changing area 121 is formed by a set of these areas. May be. In this case, a discontinuous surface with a refractive index may be formed in the optical path changing region 121.

Note that the light irradiation for forming the optical path changing region 121 is not limited to the laser light irradiation. For example, the optical path changing region 121 can also be formed by allowing light having a single wavelength other than the laser to pass through the mask and condensing with a lens and forming an image on a part of the optical path changing layer 120. it can. In this case, it is possible to perform heat treatment on a larger area at a time than when laser light is used.

As described above, according to the first embodiment, the light emitting device 100 includes the optical path changing layer 120 disposed between the translucent substrate 110 and the second electrode 150. The optical path changing layer 120 includes an optical path changing area 121 and a base area 122. In the process of light passing through the optical path changing area 121, the optical path of the light is changed. Therefore, if the optical path changing area 121 does not exist, the light is not taken out from the light emitting apparatus 100 and is repeatedly reflected and attenuated in the light emitting apparatus 100. It is possible to change the optical path of the light to be taken out from the light emitting device 100. Therefore, the light extraction efficiency can be improved.

Here, the refractive index difference between the optical path changing area 121 and the base area 122 increases as the distance from the boundary between the optical path changing area 121 and the base area 122 increases inward. In general, it has been found by simulation that the transmittance in the vicinity of the critical angle suddenly changes when the refractive index gradually changes in two layers having different refractive indexes. That is, when the refractive index changes sharply at the interface, the transmittance just before the critical angle decreases, and the reflectance increases accordingly. Conversely, when the refractive index gradually changes, it is possible to realize a state where the transmittance is high until just before the critical angle. Further, it is possible to realize a structure in which the difference in refractive index between the base region 122 and the optical path changing region 121 is suppressed, and there is no significant interface between the base region 122 and the optical path changing region 121. Thereby, the occurrence of light reflection at the boundary between the base region 122 and the optical path changing region 121 is suppressed. Therefore, even when the optical path changing region 121 does not exist, the light extracted from the light emitting device 100 can be emitted from the light emitting device 100 after smoothly entering the optical path changing region 121. Thereby, the light extraction efficiency can be further improved.

In particular, when the refractive index of the optical path changing region 121 is the same as the refractive index of the base region 122 at the boundary between the optical path changing region 121 and the base region 122, Reflection can be substantially prevented from occurring. For this reason, the light extraction efficiency can be further improved.

In addition, when the refractive index difference between the optical path changing area 121 and the base area 122 gradually increases from the boundary between the optical path changing area 121 and the base area 122 toward the inward direction of the optical path changing area 121, the optical path changing area There are no places where the refractive index changes discontinuously in 121. Thereby, the reflection of the light in the optical path changing area 121 can be substantially prevented from occurring. For this reason, the light extraction efficiency can be further improved.

Further, when the dimension of the optical path changing region 121 is equal to or greater than the emission wavelength from the light emitting layer, the refraction and reflection of light at the boundary between the optical path changing region 121 and the base region 122 can be controlled more reliably (scattering can be suppressed). The light extraction efficiency can be improved. When the dimension of the optical path changing area 121 is too small, light only travels straight through the optical path changing area 121 and may not be changed in the optical path changing area 121.

Further, when the shape of the optical path changing region 121 is at least a part of a sphere having a diameter equal to or larger than the emission wavelength from the light emitting layer, the outer shape of the optical path changing region 121 is convex toward the outside of the optical path changing region 121. Includes curved surfaces. For this reason, the external shape of the optical path changing area 121 has various angles. Therefore, for light incident on the optical path changing region 121 at various angles, the direction of the light can be changed to an angle at which light can be extracted from the light emitting device 100.

Further, when the outer shape of the optical path changing region 121 includes a curved surface convex toward the second electrode 150 side, the outer shape of the optical path changing region 121 on the second electrode 150 side has various angles. Therefore, for the light incident on the optical path changing region 121 at various angles from the second electrode 150 side, the direction of the light can be changed to an angle at which light can be extracted from the light emitting device 100.

Further, since the optical path changing region 121 includes a region having a refractive index smaller than that of the base region 122, for example, as shown in FIG. 3, the direction of light obliquely traveling from the second electrode 150 side to the translucent substrate 110 side is set. Thus, the direction can be easily changed in the direction of taking out from the light emitting device 100.

Here, the first electrode 130 may be a transparent electrode made of, for example, ITO. A transparent electrode such as ITO has a high refractive index (for example, about 1.75 to 1.83). Therefore, when the optical path changing layer 120 is disposed between the translucent substrate 110 and the first electrode 130, as described above, the refractive index of the optical path changing layer 120 is set to the refractive index of the translucent substrate 110. It is preferable that the ratio is not less than 2.0 and not more than 2.0. Thereby, light can be easily extracted from the first electrode 130 to the optical path changing layer 120, and light can also be easily extracted from the optical path changing layer 120 to the translucent substrate 110.

Here, as described in Patent Document 1, when microspheres such as SiO ₂ are dispersed in a medium such as a titanium oxide layer, it is difficult to arrange the microspheres at an arbitrary position in the medium. . On the other hand, in this embodiment, for example, the optical path changing region 121 is formed by heating a part of the optical path changing layer 120 (base region 122) by irradiating light or the like. Therefore, since the optical path changing region 121 can be easily formed at a desired position in the optical path changing layer 120 with a desired size, the light emitting device 100 having a desired structure can be easily manufactured.

In the technique of Patent Document 1, since the high refractive index layer and the layer in contact with the high refractive index layer are each made of a titanium oxide layer, even if a strong barrier film is additionally formed, The titanium oxide layer may adversely affect the organic light emitting layer. On the other hand, in this embodiment, since the optical path changing layer 120 is a layer in which the refractive index of a part of the organic layer such as phthalocyanine is changed, adverse effects on the organic functional layer 140 can be suppressed.

(Second Embodiment)
FIG. 5 is a cross-sectional view showing the configuration of the light emitting device 100 according to the second embodiment.

In the case of the second embodiment, the optical path changing layer 160 having the same configuration as the optical path changing layer 120 in the first embodiment is disposed between the organic functional layer 140 and the second electrode 150. The optical path changing layer 160 includes an optical path changing area 161 similar to the optical path changing area 121 and a base area 162 similar to the base area 122. The material of the optical path changing layer 160 may be the same material as the electron injection layer (described later) of the organic functional layer 140, for example. In this case, the refractive index of the optical path changing layer 160 is about 1.5 or more and 1.8 or less.

In the case of the second embodiment, in the region where the optical path changing layer 120 is arranged in the first embodiment, for example, a high refractive index layer 190 may be arranged instead of the optical path changing layer 120. . The high refractive index layer 190 has the same material and optical characteristics as the base region 122 of the optical path changing layer 120.

Note that the organic functional layer 140 and the optical path changing layer 160 may be in contact with each other, or another layer may exist between the organic functional layer 140 and the optical path changing layer 160. Similarly, the optical path changing layer 160 and the second electrode 150 may be in contact with each other, or another layer may exist between the optical path changing layer 160 and the second electrode 150. Similarly, the translucent substrate 110 and the high refractive index layer 190 may be in contact with each other, or another layer may exist between the translucent substrate 110 and the high refractive index layer 190. . Similarly, the high refractive index layer 190 and the first electrode 130 may be in contact with each other, or another layer may exist between the high refractive index layer 190 and the first electrode 130.

When the optical path changing layer 160 is disposed between the organic functional layer 140 and the second electrode 150 as in the second embodiment, the light extraction efficiency is improved as in the first embodiment. can do.

The organic functional layer 140 may be made of a material having a high refractive index to some extent (for example, about 1.8). For this reason, when the optical path changing layer 160 is disposed between the organic functional layer 140 and the second electrode 150 as in the present embodiment, the refractive index of the optical path changing layer 160 is 1.0 or more, In addition, the refractive index is preferably equal to or lower than the refractive index of the organic functional layer 140. Accordingly, light can be easily extracted from the optical path changing layer 160 to the organic functional layer 140, and the light reflectivity at the interface between the optical path changing layer 160 and the second electrode 150 is increased, and more light is transmitted. It can be directed to the optical substrate 110 side.

(Third embodiment)
FIG. 6 is a cross-sectional view illustrating a configuration of a light emitting device 100 according to the third embodiment.

The light emitting device 100 according to the third embodiment includes an optical path changing layer 160 disposed between the organic functional layer 140 and the second electrode 150 in addition to the configuration of the first embodiment. . That is, the light emitting device 100 according to the third embodiment includes two optical path changing layers 120 and 160. The configuration of the optical path changing layer 120 is the same as that of the first embodiment, and the configuration of the optical path changing layer 160 is the same as that of the second embodiment.

Even in the case of having two optical path changing layers 120 and 160 as in the third embodiment, the light extraction efficiency can be improved as in the first embodiment.

(Fourth embodiment)
In the case of the fourth embodiment, the optical path changing region 121 is different from the first embodiment in that it is polycrystallized. That is, the optical path changing region 121 is obtained by crystallizing the material of the base region 122 by heating and cooling. NPB or the like becomes a spherical shape while linear crystals grow as a whole by heating and cooling. As a result, the optical path changing region 121 includes a region having a refractive index larger than that of the base region 122. In the present embodiment, since the boundary between the optical path changing region 121 and the base region 122 is the boundary between the polycrystalline sphere and the surrounding base region 122, the optical path is changed at the boundary between the optical path changing region 121 and the base region 122. The refractive index of the change region 121 is the same as the refractive index of the base region 122. For example, except for the boundary between the optical path changing region 121 and the base region 122, the refractive index of the optical path changing region 121 is larger than the refractive index of the base region 122. The refractive index of the optical path changing area 121 increases (for example, gradually) as it moves away from the boundary between the optical path changing area 121 and the base area 122 inward of the optical path changing area 121.

In order to form the optical path changing region 121 having a refractive index larger than that of the base region 122, a material whose refractive index is increased by heating is used as the material of the optical path changing layer 120 (base region 122). The optical path changing layer 120 (base region 122) is configured by heating a part of the optical path changing layer 120 (base region 122) of such material in the same manner as in the first embodiment and then cooling. Crystallization of the material occurs. As a result, the refractive index of the portion becomes higher than the refractive index of the surrounding portion (that is, the base region 122), and gradually increases as the refractive index of the portion moves away from the base region 122, for example. As a material of the optical path changing layer 120, for example, NPB (N, N-di (naphthalene-1-yl) -N, N-diphenyl-benzidine) used as a material of the organic functional layer 140 can be used.

FIG. 7 is a diagram illustrating an example of a change characteristic of the refractive index from the optical path changing layer 120 to the translucent substrate 110 of the light emitting device 100 according to the fourth embodiment. That is, FIG. 7 shows another example of the change characteristic of the refractive index from one end A1 to the other end A2 of the line segment A in FIG. For example, in the base region 122, the refractive index is constant regardless of the position (region R1 in FIG. 7). The refractive index of the boundary between the base region 122 and the optical path changing region 121 (the boundary between the region R1 and the region R2 in FIG. 7) is the same as the refractive index of the base region 122. In the optical path changing region 121, the refractive index gradually increases as the distance from the boundary between the optical path changing region 121 and the base region 122 increases, that is, toward the center of the above-described spherical shape (a spherical shape whose diameter is equal to or larger than the emission wavelength from the light emitting layer). Has increased (region R2 in FIG. 7). Further, the refractive index gradually decreases again from the spherical center toward the translucent substrate 110 (region R3 in FIG. 7). That is, the refractive index of the optical path changing region 121 is the same as the refractive index of the base region 122 at the boundary with the base region 122, and gradually increases as the distance from the boundary increases. In addition, the refractive index of the translucent substrate 110 is smaller than the refractive index of the optical path changing layer 120 (region R4 in FIG. 7). Also in the case of the fourth embodiment, the direction of light is gradually changed in the process of light passing through the optical path changing region 121.

In the above description, in the fourth embodiment, the example in which the optical path changing layer 120 is disposed between the translucent substrate 110 and the first electrode 130 has been described. However, an optical path changing layer having an optical path changing region that is crystallized and has a refractive index larger than that of the base region may be disposed between the organic functional layer 140 and the second electrode 150. That is, the refractive index of the optical path changing region 161 of the optical path changing layer 160 of the second embodiment or the third embodiment may be larger than the refractive index of the base region 162. In this case, as the material of the optical path changing layer 160, for example, a material having a refractive index lower than the refractive index of the organic functional layer 140 and having a higher refractive index by heating is used.

When the optical path changing layer 160 is formed between the organic functional layer 140 and the second electrode 150 as in the second embodiment (and the third embodiment), by partially heating and cooling with a laser, It is preferable to form the crystallized optical path changing region 161 as in the fourth embodiment. In this case, since the output (power) of the laser can be suppressed compared to Example 1, damage to the organic functional layer 140 when the optical path changing region 161 is formed can be suppressed. When irradiating a material with a laser with a larger output, after forming an electrode 150 having a film thickness that allows laser transmission, the optical path changing layer 160 is partially heated and cooled by the laser to be crystallized, and then the electrode 150 The film thickness of the electrode 150 is increased until the film thickness is such that light can be reflected.

FIG. 8 is a cross-sectional view of an essential part showing an example of the operation of the light emitting device according to the fourth embodiment, and only the organic functional layer 140, the optical path changing layer 160, and the second electrode 150 are illustrated. Here, when the optical path changing layer 160 having the optical path changing area 161 similar to the optical path changing area 121 having the refractive index characteristic as described in FIG. 7 is disposed between the organic functional layer 140 and the second electrode 150. Will be described.

If there is no optical path changing region 161 in the optical path changing layer 160, it is assumed that there is light traveling in the order of the optical paths L11 and L12 shown in FIG. That is, the light travels obliquely downward in the optical path changing layer 160 (optical path L11), and then reflects on the second electrode 150 and travels obliquely upward (optical path L12). Further, this light is then transmitted to the interface between the optical path changing layer 120 and the translucent substrate 110 (when the optical path changing layer 120 exists) or to the interface between the first electrode 130 and the translucent substrate 110 (optical path changing). Suppose the layer 120 is not present) and proceed diagonally downward.

In the case of the present embodiment, since the optical path changing region 161 exists in the optical path changing layer 160, the optical path of this light gradually goes downward in the process of passing through the optical path changing region 161 as shown by the optical path L1. Be changed. This light is then reflected by the second electrode 150 and travels as indicated by the optical path L2. Here, the optical path L2 is an interface between the optical path changing layer 120 and the translucent substrate 110 (when the optical path changing layer 120 is present) or an interface between the first electrode 130 and the translucent substrate 110 (optical path changing layer). It is assumed that the angle is less than the critical angle (when 120 does not exist). Therefore, this light can be incident on the light transmitting substrate 110 side from the optical path changing layer 120 or the first electrode 130, and further this light is further transmitted from the light transmitting substrate 110 to the upper side (that is, outside the light emitting device). Can be radiated.

Thus, according to the fourth embodiment, the same effect as that of the first embodiment can be obtained.

(Example 1)
In Example 1, an example of a more specific configuration of the light emitting device 100 according to the first embodiment will be described. FIG. 9A is a plan view showing the configuration of the light emitting device according to Example 1, and FIG. 9B is a cross-sectional view taken along the line BB in FIG. 9A. 9B and 9A are upside down from FIG.

The first electrode 130 constitutes an anode. The plurality of first electrodes 130 each extend in the Y direction in a strip shape. Adjacent first electrodes 130 are spaced apart from each other at a constant interval in the X direction orthogonal to the Y direction. Each of the first electrodes 130 is made of a metal oxide conductor such as ITO or IZO, for example. The refractive index of the first electrode 130 is approximately the same as that of the optical path changing layer 120 (for example, approximately 1.8). A bus line 170 for supplying a power supply voltage to the first electrode 130 is formed on each surface of the first electrode 130. An insulating film 180 is formed on the optical path changing layer 120 and the first electrode 130. In the insulating film 180, a plurality of stripe-shaped openings each extending in the Y direction are formed. Thus, a plurality of banks (partition walls) made of the insulating film 180 are formed. Each of the openings formed in the insulating film 180 reaches the first electrode 130, and the surface of each first electrode 130 is exposed at the bottom of the opening. An organic functional layer 140 is formed on the first electrode 130 in each opening of the insulating film 180. The organic functional layer 140 is configured by stacking a hole injection layer 141, a hole transport layer 142, a light emitting layer 143 (light emitting layers 143R, 143G, 143B), and an electron transport layer 144 in this order. Materials for the hole injection layer 141 and the hole transport layer 142 include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by fluorene groups, hydrazones. Derivatives, silazane derivatives, silanamine derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like. The light emitting layers 143R, 143G, and 143B are made of a fluorescent organometallic compound that emits red light, green light, and blue light, respectively. The light emitting layers 143R, 143G, and 143B are arranged side by side in a state of being separated from each other by a bank made of the insulating film 180. That is, the organic functional layer 140 forms a plurality of light emitting regions separated by banks. An electron transport layer 144 is formed so as to cover the surfaces of the light emitting layers 143R, 143G, 143B and the insulating film 180. A second electrode 150 is formed so as to cover the surface of the electron transport layer 144. The second electrode 150 constitutes a cathode. The second electrode 150 is formed in a band shape. The second electrode 150 is made of a metal such as Al or an alloy having a low work function and high reflectivity. The refractive index of the organic functional layer 140 is approximately the same as that of the first electrode 130 and the optical path changing layer 120 (for example, a refractive index of approximately 1.8).

In this manner, the light emitting layers 143R, 143G, and 143B that emit red, green, and blue light are repeatedly arranged in stripes, and the red, green, and green light is emitted from the surface of the translucent substrate 110 that serves as a light extraction surface. , Blue light is mixed at an arbitrary ratio to emit light that is recognized as a single emission color (for example, white).

(Modification 1 of organic functional layer)
FIG. 10 is a diagram illustrating a first modification of the layer structure of the organic functional layer 140. The organic functional layer 140 according to Modification 1 has a structure in which a hole injection layer 141, a hole transport layer 142, a light emitting layer 143, an electron transport layer 144, and an electron injection layer 145 are stacked in this order. That is, the organic functional layer 140 is an organic electroluminescence light emitting layer. Note that instead of the hole injection layer 141 and the hole transport layer 142, one layer having the functions of these two layers may be provided. Similarly, instead of the electron transport layer 144 and the electron injection layer 145, a single layer having the functions of these two layers may be provided (see Example 1 (FIG. 9B)).

In the first modification of the organic functional layer, the light emitting layer 143 is, for example, a layer that emits red light, a layer that emits blue light, a layer that emits yellow light, or a layer that emits green light. In this case, in a plan view, a region having a light emitting layer 143 that emits red light, a region having a light emitting layer 143 that emits green light, and a region having a light emitting layer 143 that emits blue light are repeatedly provided. (See Example 1 (FIG. 9B)). In this case, when each region emits light simultaneously, the light emitting device 100 emits light in a single light emission color such as white.

Note that the light emitting layer 143 may be configured to emit light in a single light emission color such as white by mixing materials for emitting a plurality of colors.

(Variation 2 of the organic functional layer)
FIG. 11 is a diagram illustrating a second modification of the layer structure of the organic functional layer 140. The light emitting layer 143 of the organic functional layer 140 according to Modification 2 has a configuration in which light emitting layers 143a, 143b, and 143c are stacked in this order. The light emitting layers 143a, 143b, and 143c emit light of different colors (for example, red, green, and blue). The light emitting layers 143a, 143b, and 143c emit light at the same time, so that the light emitting device 100 emits light in a single light emission color such as white.

As mentioned above, although embodiment and the Example were described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

For example, in the above example, the shape of the optical path changing region (121, 161) is an example in which the diameter is at least a part of a sphere having a wavelength equal to or greater than the emission wavelength from the light emitting layer, in particular, the outer shape of the optical path changing region is the second electrode 150 side. An example including a convex curved surface has been described. However, the optical path changing region (121, 161) may be formed in other shapes.

In addition, the light irradiation for forming the optical path changing region (121, 161) is not limited to spot irradiation, but by intermittently irradiating, an optical path changing region having a structure like a grating (diffraction grating) ( 121, 161) may be formed.

Further, as the optical path changing area (121, 161), the refractive index difference between the optical path changing area 121 and the base area 122 increases as the distance from the boundary between the optical path changing area 121 and the base area 122 increases inward. However, the optical path changing region (121, 161) may be a bubble formed in the base region (122, 162).

Further, the example in which the refractive index of the optical path changing region 121 is the same as the refractive index of the base region 122 at the boundary between the optical path changing region 121 and the base region 122 has been described. It may change continuously. For example, when the base region 122 is irradiated with laser light with stronger energy, a discontinuous surface with a refractive index may be formed at the boundary between the optical path changing region 121 and the base region 122.

Claims (12)

A translucent substrate;
A translucent first electrode disposed on one surface side of the translucent substrate;
A second electrode disposed on the opposite side of the translucent substrate with respect to the first electrode;
An organic functional layer including at least a light-emitting layer and disposed between the first electrode and the second electrode;
An optical path changing region that changes an optical path of the light in the process of transmitting light; and a base region other than the optical path changing region, and is disposed between the translucent substrate and the second electrode. An optical path changing layer,
With
The light emitting device, wherein a difference in refractive index between the optical path changing region and the base region increases as the distance from the boundary between the optical path changing region and the base region increases inward of the optical path changing region. The light emitting device according to claim 1, wherein a refractive index of the optical path changing region is the same as a refractive index of the base region at the boundary. 3. The light emitting device according to claim 1, wherein the refractive index difference gradually increases as the distance from the boundary increases inward of the optical path changing region. The light emitting device according to claim 1 or 2, wherein the dimension of the optical path changing region is equal to or greater than a light emission wavelength from the light emitting layer. The light-emitting device according to claim 4, wherein the shape of the optical path changing region is at least a part of a sphere having a diameter equal to or greater than the emission wavelength from the light-emitting layer. The light emitting device according to claim 1 or 2, wherein an outer shape of the optical path changing region includes a curved surface that is convex toward the second electrode side. 3. The light emitting device according to claim 1, wherein the optical path changing region includes a region having a refractive index smaller than that of the base region. The optical path changing region is crystallized,
The light emitting device according to claim 1, wherein the optical path changing region includes a region having a refractive index larger than that of the base region. The optical path changing layer is disposed between the translucent substrate and the first electrode,
The light emitting device according to claim 7, wherein a refractive index of the optical path changing layer is not less than a refractive index of the translucent substrate and not more than 2.0. The optical path changing layer is disposed between the organic functional layer and the second electrode,
The light-emitting device according to claim 7, wherein a refractive index of the optical path changing layer is 1.0 or more and not more than a refractive index of the organic functional layer. 3. The light emitting device according to claim 1, wherein the optical path changing region is formed by heating a part of the base region. Forming a translucent first electrode on one surface side of the translucent substrate;
Forming an organic functional layer including at least a light emitting layer on a side opposite to the light-transmitting substrate with respect to the first electrode;
Forming a second electrode on the side opposite to the first electrode with respect to the organic functional layer;
An optical path changing layer including an optical path changing area for changing an optical path of the light in the process of transmitting light, and a base area other than the optical path changing area, the light-transmitting substrate, the second electrode, Forming between, and
With
In the step of forming the optical path changing layer, a difference in refractive index between the optical path changing area and the base area increases as the distance from the boundary between the optical path changing area and the base area increases inward of the optical path changing area. And a method of manufacturing a light emitting device for forming the optical path changing layer.

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