JP2015011893A - Organic light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance light extraction efficiency of an organic light-emitting element.SOLUTION: In an organic light-emitting element including a transparent electrode layer, an organic layer including a luminous layer, a dielectric layer in contact with at least the transparent electrode layer and organic layer, and a metal electrode layer, a laminate of the transparent electrode layer and organic layer and the dielectric layer form a sea-island structure in a plane including the dielectric layer and laminate. When the direction of the metal electrode layer is the upper side in the vertical cross-section of the organic light-emitting element, the uppermost side position in the upper surface of the dielectric layer is located on the upper side of the lowermost position in the upper surface of the luminous layer in the organic layer on the transparent electrode. The refractive index nof the dielectric layer is smaller than that nof the organic layer (n<n), and also smaller than that nof the transparent electrode layer (n<n).

Description

  The present invention relates to an organic light emitting device.

  An organic light emitting element has a structure in which an organic compound layer containing a light emitting material is sandwiched between an anode and a cathode. In particular, a light extraction technique for extracting light emitted from a surface light source to the outside has been developed. For example, Patent Document 1 includes an electroluminescent layer that includes a laminate of an electrode and a dielectric layer, includes a cavity that penetrates only the dielectric or both the dielectric and the electrode, and covers the inner surface of the cavity with an electroluminescent coating material. A cent element is described. Patent Document 2 includes a first electrode, a light emitting layer, and a second electrode formed on a transparent substrate, and a diffraction grating is formed in the light emitting layer because the first electrode has a periodic structure. A surface light emitting device is described in which emitted light is diffracted in the direction of a transparent substrate.

Special table 2010-509729 JP 2007-080890 A

The organic EL device has a bottom emission type in which light is extracted from the support substrate (transparent substrate) side and a top emission type in which light is extracted from the opposite side of the support substrate according to the direction in which the light generated in the organic light emitting layer is extracted. And divided. For example, in the case of the bottom emission type, the light emitting layer of the organic light emitting element is made of an organic compound and the like, and holes injected from a transparent electrode (for example, ITO electrode) and electrons injected from a back electrode (metal electrode) Recombine and emit light. Of the light emitted from the light-emitting layer, the critical angle is the incident angle (the angle between the incident light and the normal of the incident interface) at the interface between the transparent electrode and the transparent substrate and the exit surface from the transparent substrate to the outside (air). The above light is totally reflected to become a waveguide mode and is not extracted outside. For these reasons, it is generally said that the light extraction efficiency of the organic EL element is about 20%, and there is a problem common to the organic EL elements that the light extraction efficiency is low.
An object of the present invention is to increase the light extraction efficiency of an organic light emitting device.

According to the present invention, there is provided an organic light emitting device comprising a transparent electrode layer, an organic layer including a light emitting layer, at least the transparent electrode layer and a dielectric layer in contact with the organic layer, and a metal electrode layer, The laminate composed of the transparent electrode layer and the organic layer and the dielectric layer form a sea-island structure in a plane including the dielectric layer and the laminate, and the metal in the vertical cross section of the organic light emitting device When the direction of the electrode layer is the upper side, the uppermost position on the upper surface of the dielectric layer is positioned higher than the lowermost position on the upper surface of the light emitting layer in the organic layer on the transparent electrode. The refractive index n ₁ of the dielectric layer is smaller than the refractive index n _{2 of the} organic layer (n ₁ <n ₂ ) and smaller than the refractive index n ₃ of the transparent electrode layer (n ₁ <n ₃ ). An organic light emitting device is provided.
Here, in the present invention, it is preferable that the uppermost position on the upper surface of the dielectric layer is located higher than the lowermost position on the upper surface of the organic layer on the transparent electrode layer.
It is preferable that at least a part of the dielectric layer is in contact with the metal electrode layer.
It is preferable that the shape of the island portion in the sea-island structure is any one of a cylinder, a truncated cone, and an inverted truncated cone with the element surface normal direction as an axis.
In the sea-island structure, it is preferable that the dielectric layer forms the island part, and the island part is formed in a columnar shape or an inverted truncated cone shape that tapers toward the transparent electrode layer side.
It is preferable that an inner angle formed by the side surface of the island portion and the bottom surface of the island portion on the metal electrode layer side is 40 ° to 90 °.
In the sea-island structure, it is preferable that the organic layer forms the island portion, and the island portion is formed in a columnar shape or a truncated cone shape that tapers toward the metal electrode layer side.
It is preferable that an inner angle formed by the side surface of the island portion and the bottom surface of the island portion on the transparent electrode layer side is 40 ° to 90 °.
In the sea-island structure, the island portion has a maximum width e of 10 μm or less (e ≦ 10 μm), and 102 ² to 10 ⁸ island portions are formed per 1 mm square on the upper surface of the transparent electrode layer. It is preferable.
It is preferable to have a substrate on the opposite side of the transparent electrode layer from the organic layer.
It is preferable to have a substrate on the opposite side of the metal electrode layer from the organic layer.

  According to the present invention, the light extraction efficiency of the organic light emitting device can be increased.

It is a figure explaining the positional relationship of the dielectric material layer of an organic light emitting element to which this Embodiment is applied, an organic layer, and a light emitting layer. It is a figure explaining 1st Embodiment of the organic light emitting element to which this Embodiment is applied. It is a figure explaining the relationship between the thickness of a dielectric material layer and an organic layer. It is a figure explaining that the light emitted in the light emitting layer in an organic layer is taken out from the substrate side in the organic light emitting element to which this embodiment is applied. It is a figure explaining the relationship between the thickness of a dielectric material layer and a transparent electrode layer. It is a figure explaining embodiment with which a dielectric material layer and a metal electrode layer contact. It is a figure explaining embodiment of the recessed part which does not penetrate a transparent electrode layer. It is a figure explaining other embodiment of the shape of a dielectric material layer. It is a figure explaining the magnitude | size of a dielectric material layer of a taper shape, and another layer. It is a figure explaining an example of the manufacturing method of the organic light emitting element to which 1st Embodiment is applied. It is a figure explaining the layer structure of a top emission type organic light emitting element. It is a figure explaining 2nd Embodiment of the organic light emitting element to which this Embodiment is applied. It is a figure explaining an example of the manufacturing method of the organic light emitting element to which 2nd Embodiment is applied. It is a figure explaining 3rd Embodiment of the organic light emitting element to which this Embodiment is applied. It is a figure explaining the organic light emitting element produced in the comparative example 1. FIG. It is a figure explaining the organic light emitting element produced in the comparative example 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary. That is, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. . The drawings used are examples for explaining the present embodiment and do not represent actual sizes. The size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Further, in this specification, “on” such as “on the layer” is not necessarily limited to the case where it is formed in contact with the upper surface, and is formed on the upper side in a separated manner or between layers. It is used in a sense that includes an intervening layer.

<Organic light emitting device>
FIG. 1 is a diagram illustrating the positional relationship between the dielectric layer 13, the organic layer 14, and the light emitting layer 145 of the organic light emitting element 100 to which the present exemplary embodiment is applied.

As shown in FIG. 1, in the vertical cross section of the organic light emitting device 100, when the direction of the metal electrode layer 15 is the upper side and the direction of the substrate 11 is the lower side, the uppermost position 161 on the upper surface of the dielectric layer 13 is The upper surface 141 of the light emitting layer 145 in the organic layer 14 is located above the lowest position 142. Further, the uppermost position 161 on the upper surface of the dielectric layer 13 is located above the lowermost position 143 on the upper surface of the organic layer 14 on the transparent electrode layer 12.
As described above, in the organic light emitting device 100 to which the present embodiment is applied, the uppermost position 161 on the upper surface of the dielectric layer (region) 13 is set to the portion where the organic layer 14 is the thinnest (however, the dielectric of the organic layer 14). The upper surface position of the light emitting layer 145 (the position 142 in FIG. 1) or the upper surface position (the position 143 in FIG. 1) of the light emitting layer 145 is higher than the upper surface position of the light emitting layer 145.

  Conventionally, considering the refraction of light in organic light emitting devices, when using a low refractive index dielectric, a portion of the light incident from the top surface of the dielectric is totally reflected at the interface with the dielectric, so the front is effectively There is a tendency not to be taken out. On the other hand, the organic light emitting device 100 to which the present embodiment is applied emits light by forming the light emitting position in the light emitting layer 145 in the organic layer 14 to be lower than the upper surface of the dielectric layer 13. The light of the layer 145 enters from the side surface of the dielectric layer 13 and can be effectively extracted from the substrate 11 side.

  Further, for example, as described in FIG. 2 or FIG. 4 in Patent Document 1 described above, when the organic light emitting element forms a sea-island structure of an organic layer and (dielectric layer / transparent electrode layer), organic The interface between the transparent electrode layer and the transparent electrode layer is an interface where the emitted light is incident on the high refractive index layer from the low refractive index layer, and the light is refracted away from the normal direction of the substrate. It won't be easy. As will be described later, at least a part of the dielectric layer 13 of the organic light emitting device 100 may be in contact with the metal electrode layer 15.

Next, in the organic light emitting device 100 to which the present embodiment is applied, the refractive index n ₁ of the dielectric layer 13 is smaller than the refractive index n ₂ of the organic layer 14 (n ₁ <n ₂ ), and to be less than the refractive index _{n 3} of the transparent electrode layer 12 _(n 1 _{<n 3),} each component (the transparent electrode layer 12, dielectric layer 13, the organic layer 14) is the material of choice.

As shown in FIG. 1, the present embodiment employs a structure in which a metal electrode layer 15 is laminated on the organic layer 14. The light emitting region in the organic light emitting device 100 is limited to the region of the organic layer 14 surrounded by the transparent electrode layer 12, the dielectric layer 13, and the metal electrode layer 15.
As a result, the light emitted from the light emitting region of the organic layer 14 and guided through the organic layer 14 is extracted from the substrate 11 side by the light refraction phenomenon at the interface between the organic layer 14 and the side surface of the dielectric layer 13. Can do. Further, the light guided in the transparent electrode layer 12 can be similarly extracted from the substrate 11 side by the light refraction phenomenon at the interface between the transparent electrode layer 12 and the side surface of the dielectric layer 13.
Although FIG. 1 shows an element configuration having the substrate 11 on the transparent electrode layer 12 side, the organic light emitting element 100 to which this embodiment is applied is not limited to this configuration, and the substrate 11 is made of the metal electrode layer 15. It is good also as a structure which has in the side.

(First embodiment)
FIG. 2 is a diagram for explaining a first embodiment of an organic light emitting device 100 to which the present embodiment is applied. 2A is a schematic overhead view including a partial cross-sectional view of the organic light emitting element 100, and FIG. 2B is a schematic overhead view for explaining the internal structure of the organic light emitting element 100. FIG. ) Is a schematic partial cross-sectional view of the organic light emitting device 100.
As shown in FIGS. 2A to 2C, the organic light emitting device 100 includes a substrate 11, a transparent electrode layer 12 formed on the substrate 11 when the substrate 11 side is down, As shown, an organic layer 14 including a light emitting layer (not shown) and including one or more layers (not shown) including an organic compound, and a metal electrode layer 15 are sequentially provided. In addition, this is a bottom emission type light emitting element in which light generated in a light emitting layer (not shown) in the organic layer 14 is extracted from the substrate (transparent substrate) 11 side. Further, a recess 16 is formed on the surface of the transparent electrode layer 12 on the organic layer 14 side. In the present embodiment, the recess 16 is formed through the transparent electrode layer 12.

Furthermore, the dielectric layer 13 is formed so as to have a convex portion 131 that fills the concave portion 16 of the transparent electrode layer 12 and forms an island-shaped region in contact with the side surface of the organic layer 14. The organic layer 14 is formed in contact with the upper surface of the transparent electrode layer 12 and the side surface of the convex portion 131 of the dielectric layer 13 (portion protruding from the upper surface of the transparent electrode layer 12). Thus, in the present embodiment, the dielectric layer 13 is formed so as to be in contact with the transparent electrode layer 12 and the organic layer 14.
As is clear from FIGS. 2A and 2B, in the organic light emitting device 100 to which the present exemplary embodiment is applied, a laminate including the transparent electrode layer 12 and the organic layer 14 and the dielectric layer 13 are used. Form a sea-island structure in a plane including the dielectric layer 13 and the laminated body. And in the case of the organic light emitting element 100, the laminated body which consists of the transparent electrode layer 12 and the organic layer 14 is a sea part, and the dielectric material layer 13 comprises the island part.

  In the present embodiment, from the surface of the organic layer 14 in contact with the transparent electrode layer 12 to the upper surface 141 of the light emitting layer 145 (see FIG. 1) included in the organic layer 14 (the organic layer portion of the light emitting region) on the transparent electrode. Is the distance a from the position of the upper surface of the transparent electrode layer 12 of the dielectric layer 13 to the uppermost position 161 (see FIG. 1) on the upper surface of the convex portion 131 of the dielectric layer 13 (c ≦ a). Thereby, the light 150 emitted from the light emitting point (light emitting point) 140 in the light emitting region of the organic layer 14 and guided in the organic layer 14 is reflected at the interface between the organic layer 14 and the side surface of the convex portion 131 of the dielectric layer 13. The light can be extracted from the substrate 11 side by refraction of light.

FIG. 3 is a diagram for explaining the relationship between the thicknesses of the dielectric layer 13 and the organic layer 14. The same components as those in FIG.
As shown in FIG. 3A and FIG. 3B, the organic layer includes a light emitting layer (not shown) and is composed of a single layer containing an organic compound or a plurality of stacked layers (not shown). The minimum value d of the thickness of the portion of the layer 14 on the transparent electrode layer 12 (the portion of the organic layer 14 in the light emitting region) is the convex portion of the dielectric layer 13 from the position of the upper surface of the transparent electrode layer 12 of the dielectric layer 13. The upper surface 131 is formed so as to have a distance a or less (d ≦ a) to the uppermost position 161 (see FIG. 1).
By forming in this way, light emitted from the light emitting layer 145 in the organic layer 14 in the lateral direction is more reliably incident on the interface between the organic layer 14 and the dielectric layer 13, so that the light extraction efficiency is further improved.

Here, FIG. 4 is a diagram illustrating that light generated in the light emitting layer in the organic layer 14 is extracted from the substrate 11 side in the organic light emitting device 100 to which the present exemplary embodiment is applied.
As described above, in the configuration in which the dielectric layer 13 is formed so as to be in contact with both the transparent electrode layer 12 and the organic layer 14 formed on the substrate, the interface 13A between the organic layer 14 and the dielectric layer 13, and the transparent electrode Each of the interfaces 13B between the layer 12 and the dielectric layer 13 is an interface through which emitted light enters the low refractive index layer (dielectric layer 13) from the high refractive index layer (organic layer 14 or the transparent electrode layer 12). .

  Here, for example, light A that is emitted from a light emitting point (light emitting point) 140 in the light emitting region in the organic layer 14 and incident on the interface 13A and light B incident on the interface 13B are considered. As shown in FIG. 4, the lights A and B are both refracted so as to approach the normal direction of the substrate 11. Thereby, the incident angle of light at the interface between the transparent electrode layer 12 and the substrate 11 and the outer surface of the substrate 11 is changed to a smaller angle. Therefore, the light A and the light B are extracted from the substrate 11 side without total reflection at these interfaces (the interface between the transparent electrode layer 12 and the substrate 11 and the outer surface of the substrate 11). As described above, by adopting an element configuration having a sea-island structure of the transparent electrode layer 12 and the organic layer 14 and the dielectric layer 13 having a refractive index lower than these, total reflection inside the element can be suppressed, and the outside The extracted light increases, and the light extraction efficiency is improved.

Here, in the organic light emitting device 100 to which the present exemplary embodiment is applied, the refractive index modulation structure based on the sea-island structure has periodicity even in the in-plane direction of the substrate 11 and has no periodicity. It may be periodic.
In general, when the period of the refractive index modulation structure is sufficiently larger than the wavelength of the emitted light, the refraction effect as described above is dominant regardless of whether the refractive index modulation structure is periodic or aperiodic. It is considered that light is extracted.
On the other hand, when the period of the refractive index modulation structure is a periodical refractive index modulation structure that is equal to or less than the wavelength of the emitted light, the effect of diffraction (diffraction grating) and the effect of photonic crystal become dominant. It is thought that light is extracted.

In the present embodiment, the island portion of the dielectric layer 13 is periodically arranged in at least one direction in the plane of the substrate 11 in the laminated structure of the organic layer 14 and the transparent electrode layer 12, and the arrangement period is When the size is equal to or smaller than the wavelength of the emitted light, such a refractive index modulation structure acts as a diffraction grating. That is, the light incident on the diffraction grating from the organic layer 14 is strongly extracted at a predetermined angle that changes the traveling direction of the light. Accordingly, in the absence of this diffraction grating, the traveling direction of light is totally changed so as to be totally reflected at the interface between the transparent electrode layer 12 and the substrate 11 and the outer surface of the substrate 11, and the incident angle to these interfaces is changed to the critical angle. The light can be made smaller, and the amount of light extracted outside the substrate 11 can be increased.
Above, in order to change the traveling direction of light by refraction and diffraction, refractive index difference between the sea and the islands of the sea-island structure, i.e. the refractive index n ₁ of the refractive index n ₂ and the dielectric layer 13 of the organic layer 14 The difference and the difference between the refractive index n ₃ of the transparent electrode layer 12 and the refractive index n ₁ of the dielectric layer 13 are preferably larger than 0.1.

A photonic crystal is a structure whose refractive index differs periodically and whose period is equal to or less than the wavelength of light. This periodic refractive index distribution forms a forbidden band (photonic band gap) in which light in a specific wavelength range cannot exist.
In the organic light emitting device 100 to which the present embodiment is applied, when the period is a refractive index modulation structure and the period is equal to or less than the wavelength of the emitted light, it is a diffraction grating as described above, and It can be regarded as a nick crystal.
In the organic light emitting device 100 to which this embodiment is applied, the laminated structure of the organic layer 14 and the transparent electrode layer 12 and the sea-island structure of the dielectric layer 13, for example, the islands in a square lattice shape or a hexagonal lattice shape in plan view. When regularly arranged, it can be regarded as a two-dimensional photonic crystal.

  In this two-dimensional photonic crystal, since a photonic band gap is formed in the two-dimensional in-plane direction, light having a wavelength in the photonic band gap cannot exist in the two-dimensional in-plane direction. On the other hand, in a direction perpendicular to the two-dimensional plane, no photonic band gap is formed, so that light can be emitted. With this mechanism, light that cannot travel in the in-plane direction is redistributed in the vertical direction, so that the light can be efficiently extracted to the substrate (transparent substrate) 11 side.

  Although not shown, an anode terminal portion that is electrically connected to the transparent electrode layer 12 and is connected to the transparent electrode layer 12 and a power source is formed outside the light emitting layer forming region on the substrate 11. ing. Below, each structure of the organic light emitting element 100 is demonstrated.

(Substrate 11)
The substrate 11 serves as a support for forming the transparent electrode layer 12, the dielectric layer 13, the organic layer 14 including the light emitting layer 145, and the metal electrode layer 15. A material that satisfies the mechanical strength required for the organic light emitting device 100 is used for the substrate 11. The thickness of the substrate 11 is appropriately selected depending on the required mechanical strength and is not particularly limited. In the present embodiment, it is preferably 0.1 mm to 10 mm, more preferably 0.25 mm to 2 mm.

  As a material used for the substrate 11, when light emitted from the light emitting layer 145 is extracted from the substrate 11 side, it is necessary to have transparency to the light. In the present embodiment, “transmitting to light” means that it is only necessary to transmit visible light in a certain wavelength range emitted from the light emitting layer 145, and is transparent over the entire visible light region. Need not be. However, in this Embodiment, it is preferable that the board | substrate 11 permeate | transmits the light of wavelength 450nm-wavelength 700nm as visible light. Further, the transmittance is preferably 50% or more, and more preferably 70% or more at the wavelength where the emission intensity is maximum.

  Specifically, the material of the substrate 11 that satisfies such conditions includes glass such as sapphire glass, soda glass, and quartz glass, or transparent metal oxide; transparent such as acrylic resin, polycarbonate resin, polyester resin, and silicone resin. Resin; Transparent metal nitride such as aluminum nitride can be used. In addition, when using the said transparent resin, soda glass, etc. as the board | substrate 11, the light transmittance is impaired so that water, oxygen, a metal ion, etc. may not diffuse into the transparent electrode layer 12 grade | etc., Laminated | stacked on the board | substrate 11. It is preferable to form a barrier thin film such as a silicon oxide film on the upper surface of the substrate 11 within a range that does not exist.

  When it is not necessary to extract light emitted from the light emitting layer 145 from the substrate 11 side, the material of the substrate 11 is not limited to the transparent material described above, and an opaque material can also be used. Specifically, such materials include silicon (Si), copper (Cu), silver (Ag), gold (Au), platinum (Pt), tungsten (W), titanium (Ti), tantalum (Ta), A simple substance such as niobium (Nb), an alloy containing these, stainless steel, or the like can be given. As the material of the opaque substrate 11, a metal material having high light reflectivity is preferable in order to extract more light emitted from the light emitting layer 145 to the outside. Moreover, you may use what formed the light reflection film which consists of a light-reflective metal material on the surface of said light-transmitting material.

(Transparent electrode layer 12)
In the present embodiment, the transparent electrode layer 12 functions as an anode that injects holes into the organic layer 14 by applying a voltage between the transparent electrode layer 12 and the metal electrode layer 15. As a material used for the transparent electrode layer 12 as such an anode, a material having high electrical conductivity and a work function of 4.5 eV or more is preferable. The work function is measured by a method such as ultraviolet photoelectron spectroscopy.

  When light emitted from the light emitting layer 145 is extracted from the substrate 11 side (bottom emission type), the material for forming the transparent electrode layer 12 needs to be transparent to this light. Such a material is preferably a metal oxide, and examples thereof include ITO (indium tin oxide), IZO (indium zinc oxide), and tin oxide. Moreover, you may use the electroconductive material which consists of organic substances, such as a polyaniline derivative, a polythiophene derivative, and the mixture of these polymers, and a polystyrene sulfonic acid.

  In the case where it is not necessary to extract light emitted from the light emitting layer 145 from the substrate 11 side (top emission type), instead of the transparent electrode layer 12, the metal materials mentioned as the opaque material usable for the substrate 11 are used as the electrode. Can be used as a layer. In this case, this electrode layer can also serve as the substrate 11.

Here, FIG. 5 is a diagram for explaining the relationship between the thickness b of the dielectric layer 13 and the transparent electrode layer 12. The same components as those in FIG.
In the present embodiment, the thickness b of the transparent electrode layer 12 is formed in the range of 10 nm to 1 μm, for example. However, 50 nm or more is preferable from the viewpoint of reducing sheet resistance, and 500 nm or less is preferable in that high light transmittance is maintained. In addition, when using the opaque electrode layer which consists of metal materials instead of the transparent electrode layer 12, 15 nm-10 mm are preferable, and 50 nm-2 mm are more preferable.
Further, the height of the convex portion 131 of the dielectric layer 13 with respect to the thickness b (range of 10 nm to 1 μm) of the transparent electrode layer 12 (from the upper surface of the transparent electrode layer 12 to the uppermost surface of the convex portion 131 of the dielectric layer 13). It is formed so that the ratio (a / b) of the distance a) to the upper position is in the range of 0.3-10.

  In this embodiment, from the viewpoint of facilitating the injection of holes from the transparent electrode layer 12 to the organic layer 14, molybdenum (Mo) oxidation is performed on the surface of the transparent electrode layer 12 as an anode surface modification layer. A layer having a thickness of 1 nm to 200 nm made of a material, amorphous carbon, carbon fluoride, or the like, or a layer having an average film thickness of 10 nm or less made of a metal oxide, a metal fluoride, or the like may be provided.

(Dielectric layer 13)
The dielectric layer 13 is formed so as to fill the concave portion 16 formed in the transparent electrode layer 12 and to have a convex portion 131 protruding from the surface of the transparent electrode layer 12, and the transparent electrode layer 12 and the metal electrode layer 15. And isolated. Therefore, the dielectric layer 13 is preferably a material having a high electrical resistivity. Specifically, the electrical resistivity is preferably 10 ⁸ Ω · cm or more, and more preferably 10 ¹² Ω · cm or more. Specific examples of the material for the dielectric layer 13 include metal nitrides such as silicon nitride, boron nitride, and aluminum nitride; and metal oxides such as silicon oxide and aluminum oxide. Furthermore, polymer compounds such as polyimide, polyvinylidene fluoride, and parylene; spin-on glass (SOG) and the like can also be used.

Here, FIG. 6 is a diagram illustrating an embodiment in which the dielectric layer 13 and the metal electrode layer 15 are in contact with each other. The same components as those in FIG.
In the present embodiment, a recess 16 is formed through the transparent electrode layer 12, and the dielectric layer 13 fills the recess 16. 6A, the height a of the convex portion 131 of the dielectric layer 13 and the thickness d of the organic layer 14 are equal, the upper surface of the convex portion 131 of the dielectric layer 13 is in contact with the metal electrode layer 15, and The side surface of the dielectric layer 13 is an embodiment in which only the transparent electrode layer 12 and the organic layer 14 are in contact.

  In FIG. 6B, the height a of the convex portion 131 of the dielectric layer 13 is larger than the thickness d of the organic layer 14, and a part of the organic layer 14 is formed on the upper surface of the convex portion 131 of the dielectric layer 13. In the embodiment, the side surface of the dielectric layer 13 is in contact with the transparent electrode layer 12 and the organic layer 14, and a part of the side surface is in contact with the metal electrode layer 15. FIG. 6C shows that the height a of the convex portion 131 of the dielectric layer 13 is larger than the thickness d of the organic layer 14, and the top surface of the convex portion 131 of the dielectric layer 13 and one side surface of the dielectric layer 13 are shown. In this embodiment, the portion is in contact with the metal electrode layer 15.

As shown in FIGS. 6A to 6C, in the present embodiment, it is preferable that at least a part of the dielectric layer 13 of the organic light emitting device 100 is in contact with the metal electrode layer 15. When such a structure is employed, the light emitted from the light emitting layer of the organic layer 14 is prevented from entering the dielectric layer 13, and the light extraction efficiency from the substrate 11 side tends to be improved.
In the present embodiment, as a manufacturing method for bringing at least a part of the dielectric layer 13 into contact with the metal electrode layer 15, the organic layer 14 is preferably formed on the transparent electrode layer 12 by vapor deposition. .

FIG. 7 is a diagram illustrating an embodiment of a recess that does not penetrate the transparent electrode layer 12. The same components as those in FIG.
In the present embodiment, the transparent electrode layer 12 of the organic light emitting element 101 is formed with a recess 165 that does not penetrate the transparent electrode layer 12, fills the recess 165, and the dielectric layer so that the side surface is in contact with the organic layer 14. Layer 13 is formed. In this case, the depth of the concave portion 165 of the transparent electrode layer 12 is in the range of 0.5 b or more with respect to the thickness b of the transparent electrode layer 12 in the present embodiment. If the depth of the recess 165 is excessively shallow, the extraction efficiency of light guided in the transparent electrode layer 12 tends to be reduced.

Next, as shown in FIG. 2B described above, in the present embodiment, the shape of the dielectric layer 13 is a cylindrical shape having a diameter e. The shape of the dielectric layer 13 is not limited to a cylindrical shape, and examples thereof include a polygonal column shape such as a quadrangular column. In this case, the diameter e is the maximum dimension in plan view of the dielectric layer 13 (island portion). In the present embodiment, the diameter e of the dielectric layer 13 is 10 μm or less (e ≦ 10 μm). However, it is preferably 0.1 μm or more, and more preferably 0.5 μm or more. The shapes of the plurality of dielectric layers 13 may be the same or different.
Further, in the present embodiment, the number of dielectric layers 13 is preferably in the range of 10 ² to 10 ⁸ in an arbitrary 1 mm square on the upper surface of the transparent electrode layer 12.

  In the present embodiment, the shape of the dielectric layer 13 is preferably, for example, a cylindrical shape or a polygonal column shape such as a quadrangular column from the viewpoint of easy shape control. In these shapes, the cross-sectional shape parallel to the substrate surface of the dielectric layer 13 may change in the thickness direction, or the size of the shape may change. For example, a truncated cone shape or a truncated pyramid shape may be used.

Here, FIG. 8 is a diagram for explaining another embodiment of the cross-sectional shape of the dielectric layer 13. The same components as those in FIG.
In the organic light emitting device 102 shown in FIGS. 8A and 8B, the island portion of the dielectric layer 13 in the sea-island structure is formed in a tapered inverted truncated cone shape that tapers toward the substrate 11 side. Yes.

  Since the dielectric layer 13 is formed in a tapered shape, the light 150 emitted from the light emitting point (light emitting point) 140 of the organic layer 14 and incident on the dielectric layer 13 is changed to the convexity of the organic layer 14 and the dielectric layer 13. The efficiency of extraction from the substrate 11 side tends to be increased by the refraction of light at the interface with the side surface of the portion 132. In addition, the light 151 once incident on the transparent electrode layer 12 and then incident on the dielectric layer 13 is similarly caused by the light refraction at the interface between the transparent electrode layer 12 and the side surface of the tapered dielectric layer 13. The efficiency of taking out from the side tends to be increased.

  Next, in the organic light emitting device 102 shown in FIG. 8C, the island portion of the dielectric layer 13 has a tapered inverted truncated cone shape (convex portion 133) that tapers toward the substrate 11 in the organic layer 14. ). On the other hand, the transparent electrode layer 12 is formed in a cylindrical shape that is continuous in a truncated pyramid shape. When the dielectric layer 13 has the convex portion 133 formed in a tapered shape, the extraction efficiency of light emitted from the organic layer 14 tends to be increased.

Here, FIG. 9 is a diagram for explaining the sizes of the tapered dielectric layer 13 and other layers. The same components as those in FIG. The description of the size of each part using the reference numerals in FIG. 9 is as follows.
The height a at which the dielectric layer 13 protrudes from the upper surface of the transparent electrode layer 12 (the height a of the convex portion 131 of the dielectric layer 13) is 10 nm or more and 1000 nm or less, and more preferably 50 nm or more and 400 nm or less. Chosen from.

The thickness b of the transparent electrode layer 12 is 10 nm or more and 1000 nm or less, and more preferably selected from the range of 30 nm or more and 500 nm or less.
The relationship between the distance c from the surface of the organic layer 14 in contact with the transparent electrode layer 12 to the lowermost position of the upper surface 141 of the light emitting layer 145 (see FIG. 1) and the height a of the protrusion 131 is 0. 0.1a ≦ c ≦ a, more preferably 0.2a ≦ c ≦ 0.8a.

The relationship between the minimum value d of the film thickness of the organic layer 14 on the transparent electrode layer 12 and the height a of the protrusion 131 described above is 0.1a ≦ d ≦ 1.5a, and more preferably 0.3a ≦ d ≦ 0.9a.
The diameter e of the upper surface of the dielectric layer 13 on the metal electrode layer 15 side (upper surface of the protrusion 131) is 100 nm or more and 10,000 nm or less, more preferably 300 nm or more and 5000 nm or less.

  In the case where the dielectric layer 13 formed in a tapered shape, that is, the region of the island portion of the dielectric layer 13 has an inverted truncated cone shape including a cylinder, the side surface of the island portion and the bottom surface of the island portion on the metal electrode layer 15 side are formed. The angle θ (inclination angle) on the inner side (inner side of the island part) is preferably 40 ° to 90 °, and more preferably 45 ° to 75 °. When the angle θ is excessively large (when the island has a truncated cone shape), the light guided from the light emitting point (light emitting point) 140 in the direction close to the horizontal direction toward the substrate 11 on the side surface of the island. The effect of refraction is lost. In addition, when the angle θ is excessively small, it is difficult to manufacture such a small taper angle.

  In the present embodiment, the arrangement in plan view of the plurality of island portions in the sea-island structure of the refractive index modulation structure is not particularly limited. For example, regular arrangement such as square lattice, hexagonal lattice, etc. Any of the various arrangements can be employed.

(Organic layer 14)
In the present embodiment, the organic layer 14 includes the light-emitting layer 145, and includes one layer including an organic compound or a plurality of stacked layers (not shown). As shown in FIG. 1, the organic layer 14 is formed as a continuous film covering the upper surface of the transparent electrode layer 12 and the side surface of the dielectric layer 13. The light emitting layer 145 includes a light emitting material that emits light when a voltage is applied between the transparent electrode layer 12 and the metal electrode layer 15. As such a light emitting material, a known light emitting material can be used, and any of a light emitting polymer compound and a light emitting non-polymer compound can be used. In this embodiment mode, it is preferable to use a phosphorescent organic compound or a metal complex which is a light-emitting organic material as the light-emitting material.

In the present embodiment, it is very desirable to use a cyclometalated complex as the light emitting material from the viewpoint of improving the light emission efficiency. Examples of cyclometalated complexes include 2-phenylpyridine derivatives, 7,8-benzoquinoline derivatives, 2- (2-thienyl) pyridine derivatives, 2- (1-naphthyl) pyridine derivatives, 2-phenylquinoline derivatives, and the like. Examples include iridium (Ir), platinum (Pt), and gold (Au) complexes having a ligand. Among these, iridium (Ir) complexes are particularly preferable.
The cyclometalated complex may have other ligands in addition to the ligands necessary for forming the cyclometalated complex. The cyclometalated complex includes a compound that emits light from triplet excitons, and such a compound is preferable from the viewpoint of improving luminous efficiency.

  Examples of the light-emitting polymer compound include poly-p-phenylene vinylene (PPV) derivatives such as poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene] (MEH-PPV), poly Π-conjugated polymer compounds such as fluorene derivatives and polythiophene derivatives; non-conjugated polymers in which a dye molecule and a carrier transporting compound (tetraphenyldiamine derivative, triphenylamine derivative, etc.) are introduced into the main chain or side chain. A light emitting polymer compound and a light emitting non-polymer compound may be used in combination.

  The light emitting layer 145 includes a host material together with the light emitting material, and the light emitting material may be dispersed in the host material. Such a host material preferably has a charge transporting property, and is preferably a hole transporting compound or an electron transporting compound.

The organic layer 14 may include a hole transport layer (not shown) for receiving holes from the transparent electrode layer 12 and transporting them to the light emitting layer 145. The hole transport layer is provided between the transparent electrode layer 12 and the light emitting layer 145.
As a hole transport material for forming such a hole transport layer, a known material can be used. For example, N, N′-diphenyl-N, N′-di (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (TPD), 4,4′-bis [N- (1 -Triphenylamine derivatives such as -naphthyl) -N-phenylamino] biphenyl (α-NPD), 4,4 ′, 4 ″ -tris (3-methylphenylphenylamino) triphenylamine (m-MTDATA); Carbazole; a polymer compound obtained by introducing a polymerizable substituent into the above triphenylamine derivative, and the like. The above hole transport materials may be used singly or in combination of two or more, and a plurality of hole transport layers formed from different hole transport materials may be laminated.

  Further, a hole injection layer (not shown) for relaxing the hole injection barrier may be provided between the hole transport layer and the transparent electrode layer 12. Examples of the material for forming the hole injection layer include phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, benzidine type triphenylamine, diamine type triphenylamine, hexacyanohexaazatriphenylene and the like, and also polyvinylcarbazole, polysilane. A known material such as a polymer material can be used. Furthermore, a mixture of the hole transport material used for the hole transport layer and an electron acceptor such as 2,3,5,6-tetrafluorotetracyano-1,4-benzoquinonedimethane (F4TCNQ) is used. You can also. When the transparent electrode layer 12 is formed of a material other than the conductive polymer such as ITO or IZO, in addition to the above materials, the hole injection layer is a mixture of poly (ethylenedioxythiophene) and polystyrene sulfonic acid ( A conductive polymer such as PEDOT: PSS can also be used.

  The organic layer 14 includes an electron transport layer (not shown) for receiving electrons from the metal electrode layer 15 as a cathode and transporting the electrons to the light emitting layer 145 between the light emitting layer 145 and the metal electrode layer 15. Also good. As a material that can be used for such an electron transport layer, a known material can be used. For example, aluminum complexes, zinc complexes, quinoline derivatives, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, triazine derivatives, quinoxaline derivatives, triarylborane derivatives, triphenylphosphine oxide derivatives, and the like can be given. Specifically, tris (8-quinolinolato) aluminum (abbreviation: Alq), bis [2- (2-hydroxyphenyl) benzoxazolate] zinc, bis [2- (2-hydroxyphenyl) benzothiazolate] zinc, 2 -(4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole and the like.

  Further, in order to prevent holes from passing through the light emitting layer 145 between the electron transport layer and the light emitting layer 145 and to efficiently recombine holes and electrons in the light emitting layer 145, a hole block is provided. A layer (not shown) may be provided. This hole blocking layer can also be regarded as one of the layers included in the organic layer 14. In order to form the hole blocking layer, a known material such as a triazole derivative, an oxadiazole derivative, or a phenanthroline derivative can be used.

  The thickness of each of the layers constituting the organic layer 14 is appropriately selected in consideration of charge mobility, charge injection balance, interference of emitted light, and the like, and is not particularly limited. In the present embodiment, the thickness is preferably 1 nm to 1 μm, more preferably 2 nm to 500 nm, and particularly preferably 5 nm to 200 nm.

  Further, the total thickness of the organic layer 14 obtained by adding up the thicknesses of the plurality of layers is such that the distance between the transparent electrode layer 12 and the metal electrode layer 15 is 30 nm to 1 μm, more preferably 50 nm to 500 nm. It is desirable that Note that by controlling the thickness of the organic layer 14, a microresonator structure can be formed, and the spectrum and intensity of the light extracted outside the light emitting device can be changed. In this case, one of the transparent electrode layer 12 and the metal electrode layer 15 is formed as a semi-reflective electrode made of a metal thin film having a thickness of 5 nm to 50 nm, and the other is used as a reflective electrode.

(Metal electrode layer 15)
The metal electrode layer 15 applies a voltage between the transparent electrode layer 12 and injects electrons into the organic layer 14. That is, in this embodiment, the metal electrode layer 15 is a cathode and is formed as a continuous film on the entire surface of the light emitting region on the organic layer 14. The material used for forming the metal electrode layer 15 is not particularly limited as long as it has electrical conductivity. In the present embodiment, a material having a low work function and being chemically stable is preferable. Specific examples include materials such as Al, MgAg alloys, alloys of Al and alkali (earth) metals such as AlLi and AlCa, and the like.
The thickness of the metal electrode layer 15 is preferably 10 nm to 1 μm, and more preferably 50 nm to 500 nm. However, in the case of an element structure (top emission type) that extracts light generated in the light emitting layer 145 from the side opposite to the substrate 11, it is transparent to visible light in the same manner as the transparent electrode layer 12 instead of the metal electrode layer 15. It is preferable to use a material.

  In the present embodiment, a cathode buffer layer (not shown) is disposed adjacent to the metal electrode layer 15 for the purpose of lowering the electron injection barrier from the metal electrode layer 15 to the organic layer 14 and increasing the electron injection efficiency. It may be provided on the layer 14 side. Examples of the material for the cathode buffer layer include alkali metals (sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), magnesium (Mg), alkaline earth metals (calcium (Ca), strontium ( Sr), barium (Ba)), rare earth metals (praseodymium (Pr), samarium (Sm), europium (Eu), ytterbium (Yb)), or a material selected from fluorides, chlorides and oxides of these metals And a mixture of two or more organic compounds having high electron affinity such as 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine (BCP)) and cesium ( A mixture of materials having a high electron-donating property such as Cs) is also preferably used. nm~50nm more preferably from 0.1Nm～20nm, 0.5 nm to 10 nm is more preferable.

(Other configurations)
In the organic light emitting device 100 to which the present embodiment is applied, the transparent electrode layer 12 formed in contact with the substrate 11 is an anode, and the metal electrode layer 15 formed on the organic layer 14 is a cathode. However, the anode and the cathode may be reversed. That is, the transparent electrode layer 12 may be a cathode and the metal electrode layer 15 may be an anode.

(Manufacturing method of the organic light emitting device 100)
FIG. 10 is a diagram illustrating an example of a method for manufacturing the organic light emitting device 100 to which the first embodiment is applied.
As shown in FIG. 10A, first, the transparent electrode layer 12 is formed on the substrate 11 (transparent electrode layer forming step). Next, as shown in FIG. 10B, a photoresist layer 21 is formed on the transparent electrode layer 12, and the formed photoresist layer 21 is exposed to light using a photomask having a predetermined pattern. Process by. By this process, as shown in FIG. 10C, the recess 16 penetrating the transparent electrode layer 12 is formed (recess formation step). When the tapered dielectric layer 13 is formed, the tapered recess 16 is formed.

(Method for forming recess 16)
In the present embodiment, when the recess 16 is formed by a method using photolithography, first, as shown in FIG. 10A, after forming the transparent electrode layer 12 on the substrate 11, FIG. As shown in b), a photoresist solution is applied on the transparent electrode layer 12, and the excess resist solution is removed by spin coating or the like to form a photoresist layer 21. Subsequently, the photoresist layer 21 is covered with a mask on which a predetermined pattern is drawn in advance, and the photoresist layer 21 is exposed by irradiating with ultraviolet (UV), electron beam (EB), or the like. To do.

  Here, when the same magnification exposure (for example, contact exposure, proximity exposure, etc.) is performed, a pattern of the recess 16 having the same magnification as the mask pattern is formed. Further, when reduced exposure (for example, exposure using a stepper or the like) is performed, a pattern of the recesses 16 reduced with respect to the mask pattern is formed. Next, when the photoresist layer 21 is developed using a developer, the photoresist layer 21 is partially removed corresponding to the formed pattern, and the surface of the transparent electrode layer 12 is exposed.

Next, as shown in FIG. 10C, the exposed portion of the transparent electrode layer 12 is removed by etching to form a recess 16. As the etching, either dry etching or wet etching can be used. Examples of dry etching include reactive ion etching (RIE) and inductively coupled plasma etching. As wet etching, a method of immersing in dilute hydrochloric acid or dilute sulfuric acid can be used. Note that the depth of the recess 16 can be controlled by adjusting the etching conditions (processing time, gas used, pressure, substrate 11 temperature) when etching is performed.
In order to form the side surface of the recess 16 in a shape that is nearly perpendicular to the substrate surface, a photoresist having a high etching resistance and a highly anisotropic etching method may be used as a photomask. In order to form the side surface of the concave portion 16 so as to have a forward taper (in the case of an island shape in which the concave portion tapers toward the substrate side), a photoresist having a relatively low etching resistance is used as a photomask. do it.

  Subsequently, as shown in FIG. 10D, a dielectric material layer 135 is formed so as to fill the recess 16 and cover the upper surface of the photoresist layer 21 (dielectric material layer forming step). Next, as shown in FIG. 10E, the dielectric material layer 135 above the upper surface of the photoresist layer 21 is removed by etching, and the dielectric layer 13 is formed in the recess 16 (dielectric layer). Forming step). Subsequently, as shown in FIG. 10F, the photoresist layer 21 covering the side surface of the dielectric layer 13 is removed. Finally, as shown in FIG. 10G, the organic layer 14 and the metal electrode layer 15 are formed on the transparent electrode layer 12 to obtain the organic light emitting device 100 (metal electrode layer forming step).

  In order to form each layer constituting the organic light emitting device 100, for example, resistance heating vapor deposition, electron beam vapor deposition, sputtering, ion plating, CVD, or the like can be used. In addition, when a wet film-forming method such as a coating film-forming method (that is, a method in which a target material is dissolved in a solvent and then dried on the substrate 11) is possible, for example, spin coating method, dip coating The film can be formed using a method such as a method, an ink jet method, a printing method, a spray method, or a dispenser method.

FIG. 11 is a diagram illustrating a layer configuration of a top emission type organic light emitting device.
An organic light emitting device 200 shown in FIG. 11 includes a substrate 11, a metal electrode layer 15 formed on the substrate 11 when the substrate 11 side is down, and an organic layer 14 including a light emitting layer (not shown). And a transparent electrode layer 12 in this order. A concave portion 16 is formed on the surface of the transparent electrode layer 12 on the organic layer 14 side. In the present embodiment, the recess 16 is formed without penetrating the transparent electrode layer 12.
In the organic light emitting device 200 to which the present embodiment is applied, light is extracted from the opposite side of the substrate 11 when the metal electrode layer 15 is an anode (reflection electrode) having reflection performance and the transparent electrode layer 12 is a cathode. It is formed as a top emission type element. In the case of a top emission type element, a metal electrode layer 15 as a reflective electrode is formed before the organic layer 14 is formed. Therefore, the metal electrode layer 15 is required to have a flat surface in addition to a high reflectance.

  In this case, as the material for forming the anode and the cathode, the same materials as those for forming the anode and the cathode described above can be used, respectively. The preferred ranges of the thicknesses of the transparent electrode layer 12 as the cathode and the metal electrode layer 15 as the anode are the same as the preferred ranges described above for the transparent electrode layer 12 as the anode and the metal electrode layer 15 as the cathode, respectively.

  When the metal electrode layer 15 is an anode, an anode surface modification layer is formed adjacent to the metal electrode layer 15 on the organic layer 14 side in order to facilitate injection of holes from the metal electrode layer 15 to the organic layer 14. Is provided. A cathode buffer layer may be provided for the purpose of lowering the electron injection barrier from the cathode to the organic layer 14 and increasing the electron injection efficiency. The cathode buffer layer is adjacent to the transparent electrode layer 12 serving as the cathode. It is formed on the organic layer 14 side.

  When the organic layer 14 includes a hole transport layer for receiving holes from the metal electrode layer 15 and transporting them to the light emitting layer, the hole transport layer is provided between the metal electrode layer 15 and the light emitting layer. . In addition, a hole injection layer for relaxing a hole injection barrier from the metal electrode layer 15 to the hole transport layer may be further provided, and this hole injection layer is formed between the hole transport layer and the metal electrode layer 15. Formed between.

  The organic layer 14 may include an electron transport layer for receiving electrons from the transparent electrode layer 12 serving as a cathode and transporting the electrons to the light emitting layer. The electron transport layer is interposed between the light emitting layer and the transparent electrode layer 12. It is formed.

  In addition, a hole blocking layer is provided between the electron transport layer and the light emitting layer in order to prevent holes from passing through the light emitting layer and efficiently recombine holes and electrons in the light emitting layer. The hole blocking layer may be formed on the transparent electrode layer 12 side that is a cathode adjacent to the light emitting layer.

  In the top emission type organic light emitting device 200, the metal electrode layer 15 formed in contact with the substrate 11 is an anode, and the transparent electrode layer 12 formed on the organic layer 14 is a cathode. However, the anode and the cathode may be reversed. That is, the metal electrode layer 15 may be a cathode and the transparent electrode layer 12 may be an anode.

(Second Embodiment)
Next, FIG. 12 is a figure explaining 2nd Embodiment of the organic light emitting element to which this Embodiment is applied. The same components as those in FIG. Note that the organic layer 14 and the metal electrode layer 15 are omitted.
As shown in FIG. 12, in the organic light emitting device 300 to which the present embodiment is applied, a sea-island structure composed of a laminate composed of a transparent electrode layer 12 and an organic layer 14 (see FIG. 2) and a dielectric layer 13. In FIG. 2, the laminated body composed of the transparent electrode layer 12 and the organic layer 14 (see FIG. 2) is an island part, and the dielectric layer 13 constitutes a sea part. That is, in the present embodiment, the dielectric layer 13 formed by filling the recesses (continuous recesses) 16 provided in the transparent electrode layer 12 is formed as a continuous structure. As described above, the present embodiment is different from the first embodiment in that the relationship between the laminated body including the transparent electrode layer 12 and the organic layer 14 and the sea island of the dielectric layer 13 is opposite to that of the first embodiment.

  However, as shown in FIG. 12, in this case, the recess 16 is formed so as not to penetrate the transparent electrode layer 12. That is, in the sea-island structure, when the laminated structure of (transparent electrode layer 12 / organic layer 14) is an island, a portion 121 that contacts the bottom surface of the dielectric layer 13 is left under the island of each transparent electrode layer 12. By maintaining the integral structure, the islands of the transparent electrode layers 12 are prevented from being isolated, and conduction between the island portions of the transparent electrode layer 12 is obtained.

Similar to the organic light emitting device 100 to which the first embodiment is applied, the organic light emitting device 300 to which this embodiment is applied, the refractive index n ₁ of the dielectric layer 13, the refractive index of the organic layer 14 n ₂ Each component (the transparent electrode layer 12, the dielectric layer 13, so as to be smaller (n ₁ <n ₂ ) and smaller than the refractive index n ₃ of the transparent electrode layer 12 (n ₁ <n ₃ )). The material of the organic layer 14) has been selected.

  An organic light emitting device 300 shown in FIG. 12 constitutes a bottom emission type device in which light generated in a light emitting layer (not shown) in the organic layer 14 (not shown) is extracted from the substrate (transparent substrate) 11 side. doing. However, similarly to the organic light emitting device 100 to which the first embodiment is applied, also in the organic light emitting device 300 of the present embodiment, the metal electrode layer 15 is an anode (reflecting electrode) having reflective performance, and a transparent electrode layer is used. You may comprise the top emission type | mold element from which light is taken out from the other side of the board | substrate 11 by making 12 into a cathode.

  Further, in the organic light emitting device 300 of the present embodiment shown in FIG. 12, the island part of the laminated body composed of the transparent electrode layer 12 and the organic layer 14 (see FIG. 2) has a cylindrical shape or faces the metal electrode layer 15 side. It is formed in a tapered truncated cone shape that tapers off. The angle θ (inclination angle) between the side surface of the island part and the inner side (inside of the island part) formed by the bottom surface on the substrate 11 side of the island part is preferably 40 ° to 90 °, and more preferably 45 ° to 75 °. When the angle θ is excessively large (when the island has an inverted truncated cone shape), the effect of refracting the light guided in the direction near the horizontal direction from the light emitting point toward the substrate 11 on the side surface of the island is effective. Disappear. In addition, when the angle θ is excessively small, it is difficult to manufacture such a small taper angle.

  In addition, similarly to the organic light emitting device 100 to which the first embodiment is applied, the organic light emitting device 300 to which the present embodiment is applied also has a transparent electrode from the surface in contact with the transparent electrode layer 12 in the organic layer 14. The minimum value of the distance c to the upper surface of the light emitting layer included in the organic layer 14 (the organic layer portion of the light emitting region) on the layer 12 is determined from the position of the upper surface of the transparent electrode layer 12 of the dielectric layer 13 to the dielectric layer 13. It is formed so that it may become below distance a (c <= a) to the uppermost position in the upper surface of the convex part 131. Thereby, light emitted from the light emitting layer in the organic layer 14 and guided in the organic layer 14 can be extracted from the substrate 11 side by refraction of light at the interface between the organic layer 14 and the dielectric layer 13. . Further, the minimum value d of the film thickness of the organic layer 14 on the transparent electrode layer 12 is from the position on the upper surface of the transparent electrode layer 12 of the dielectric layer 13 to the uppermost position on the upper surface of the convex portion 131 of the dielectric layer 13. The distance a is equal to or smaller than (d ≦ a). Thereby, since the light emitted from the light emitting layer in the organic layer 14 in the lateral direction is more reliably incident on the interface between the organic layer 14 and the dielectric layer 13, the light extraction efficiency is improved.

FIG. 13 is a diagram illustrating an example of a method for manufacturing an organic light emitting device to which the second embodiment is applied. The same components as those in the first embodiment shown in FIG.
The manufacturing method of the organic light emitting device 300 of the present embodiment is basically the same as that of the organic light emitting device 100 of the first embodiment. However, since the relationship between the sea islands of the transparent electrode layer 12 and the dielectric layer 13 is opposite to that of the first embodiment, the first mask pattern of the photoresist for forming the recess 16 in the transparent electrode layer 12 is used. In this embodiment, the reverse of the sea-island relationship is used.
After the step of forming the recess 16 in the transparent electrode layer 12, and subsequently the step of forming the dielectric layer 13 in the recess 16, the recess 16 of the transparent electrode layer 12 is filled as shown in FIG. A dielectric layer 13 is formed so as to protrude from the transparent electrode layer 12 (corresponding to FIG. 10F of the first embodiment).
Subsequently, the organic layer 14 and the metal electrode layer 15 are formed on the transparent electrode layer 12 to obtain the organic light emitting device 300.

  FIGS. 13B-1 and 13B-2 show a case where the organic layer 14 is formed thinner than the height at which the dielectric layer 13 protrudes from the transparent electrode layer 12. FIG. 13 (b-1) shows a structure in which a laminate composed of the transparent electrode layer 12 and the organic layer 14 forms an island portion and the dielectric layer 13 forms a sea portion on the substrate 11, and FIG. -2) shows a structure in which the metal electrode layer 15 is formed thereon. In this case, the dielectric layer 13 has a structure in which part of the upper surface and side surfaces thereof are in contact with the metal electrode layer 15.

  FIGS. 13C-1 and 13C-2 show the case where the organic layer 14 is formed thicker than the height at which the dielectric layer 13 protrudes from the transparent electrode layer 12. FIG. 13 (c-1) shows a structure in which a laminate composed of the transparent electrode layer 12 and the organic layer 14 forms an island portion and a dielectric layer 13 forms a sea portion on the substrate 11, and FIG. -2) shows a structure in which the metal electrode layer 15 is formed thereon. In this case, the upper surface and the side surface of the dielectric layer 13 are covered with the organic layer 14 and are not in contact with the metal electrode layer 15.

(Third embodiment)
FIG. 14 is a diagram for explaining a third embodiment of an organic light emitting device to which the present embodiment is applied.
An organic light emitting device 400 to which the present embodiment is applied includes a substrate 11, a transparent electrode layer 12 formed on the substrate 11, and a dielectric layer 134. In FIG. 14, the organic layer 14 including the light emitting layer and the metal electrode layer 15 are omitted.
As shown in FIG. 14, in the present embodiment, the transparent electrode layer 12 is formed with a plurality of groove-shaped recesses 16, further filled with the groove-shaped recesses 16, and protruding from the upper surface of the transparent electrode layer 12. A plurality of rod-shaped dielectric layers 134 are formed. Here, in the present embodiment, the plurality of groove-like recesses 16 are formed so as not to penetrate the transparent electrode layer 12. Further, the lower part of the side surface of the rod-shaped dielectric layer 134 is in contact with the inner side surface of the groove-like recess 16 of the transparent electrode layer 12, and the upper part of the side surface of the dielectric layer 134 is an organic layer (not shown). ).

Similar to the organic light emitting device 100 to which the first embodiment is applied, the organic light emitting device 400 to which this embodiment is applied, the refractive index n ₁ of the dielectric layer 134, the refractive index of the organic layer 14 n ₂ Each component (transparent electrode layer 12, dielectric layer 134, so as to be smaller (n ₁ <n ₂ ) and smaller than the refractive index n ₃ of the transparent electrode layer 12 (n ₁ <n ₃ ). The material of the organic layer 14) has been selected.

  The angle θ (inclination angle) between the side surface of the rod-shaped dielectric layer 134 and the bottom surface (upper surface in FIG. 14) on the metal electrode layer 15 side (inner side of the rod-shaped portion) is preferably 40 ° to 90 °. More preferably, it is 45 ° to 75 ° (the vertical cross section perpendicular to the length of the rod-like portion is rectangular or inverted trapezoidal). When the angle θ is excessively large (when the cross section of the rod-shaped part is trapezoidal), the effect of refracting the light guided from the light emitting point in the direction close to the horizontal direction toward the substrate 11 on the side surface of the island part is effective. Disappear. In addition, when the angle θ is excessively small, it is difficult to manufacture such a small taper angle.

Although not shown, in the present embodiment as well as the organic light emitting device 100 to which the first embodiment is applied, the organic layer is formed from the surface in contact with the transparent electrode layer 12 in the organic layer (not shown). The minimum value c of the distance to the upper surface of the light-emitting layer included in is less than or equal to the distance a from the position of the upper surface of the transparent electrode layer 12 of the dielectric layer 134 to the uppermost position of the upper surface of the dielectric layer 134 (c ≦ a ).
As a result, light emitted from the light emitting layer in the organic layer 14 and guided in the organic layer 14 can be extracted from the substrate 11 side by refraction of light at the interface between the organic layer 14 and the dielectric layer 134. .

  Further, the minimum value d of the film thickness of the organic layer (not shown) on the transparent electrode layer 12 is from the position of the upper surface of the transparent electrode layer 12 of the dielectric layer 134 to the uppermost position on the upper surface of the dielectric layer 134. The distance a is equal to or smaller than (d ≦ a). Thereby, since the light emitted from the light emitting layer in the organic layer 14 in the lateral direction is more reliably incident on the interface between the organic layer 14 and the dielectric layer 134, the light extraction efficiency is improved.

In addition, it is preferable to use the organic light emitting element to which this embodiment is applied stably for a long period of time and to attach a protective layer and a protective cover for protecting from the outside. As the protective layer, a polymer compound, metal oxide, metal fluoride, metal boride, silicon nitride, silicon oxide, or the like can be used. And these laminated bodies can also be used.
Further, as the protective cover, a glass plate, a plastic plate whose surface has been subjected to low water permeability treatment, a metal, or the like can be used. For example, such a protective cover is preferably bonded to the substrate 11 of the organic light emitting device 100 using a thermosetting resin or a photocurable resin, and the inside of the protective cover is sealed. In this case, it is preferable to use a spacer because a predetermined space can be maintained in the protective cover and the light emitting portion can be prevented from being damaged.
Furthermore, it becomes easy to prevent the upper metal electrode layer 15 from being oxidized by sealing an inert gas such as nitrogen, argon or helium in such a space in the protective cover. In particular, helium is preferable because it has higher thermal conductivity than other inert gases and can effectively transfer heat generated from the light emitting device to the protective cover when a voltage is applied. In addition, by installing a desiccant such as barium oxide in this space in the protective cover, it becomes easy to suppress damage to the light emitting device caused by moisture adsorbed in the process of manufacturing the organic light emitting element.

  The organic light emitting element to which this embodiment is applied can be used as a surface light source. Specific examples of the surface emitting light source include an electrophotographic apparatus, a resist exposure apparatus, a reading apparatus, a light source in an optical communication system, a backlight in a display apparatus, illumination, interior illumination, and the like.

  Hereinafter, the present invention will be described in more detail based on examples. However, the present invention is not limited to the following examples.

Example 1
An organic light emitting device having the cross-sectional structure shown in FIG. 2C is manufactured, and then the emission intensity is measured.
First, an indium tin oxide film (Indium Tin Oxide) is used as the transparent electrode layer 12 on a substrate 11 (25 mm square, thickness 0.7 mm) made of quartz glass using a sputtering apparatus (E-401s manufactured by Canon Anelva Co., Ltd.). : ITO film) (refractive index 1.9) is formed to a thickness of 120 nm.

Next, a photoresist (AZ1500 manufactured by AZ Electronic Materials Co., Ltd.) layer is formed to a thickness of about 1 μm by spin coating so as to cover the transparent electrode layer 12. Next, a mask A corresponding to a pattern in which a circle (plate thickness: 3 mm) is used as a base and circles are arranged in a hexagonal lattice shape is prepared, and using a stepper exposure apparatus (manufactured by Nikon Corporation, model NSR-1505i6), Exposure is performed at 1/5 scale. Next, after developing with a 1.2% solution of tetramethylammonium hydroxide (TMAH: tetramethyl ammonium hydroxide: (CH ₃ ) ₄ NOH), the resist layer is patterned, and then heated at 130 ° C. for 10 minutes.

Subsequently, using a reactive ion etching apparatus (RIE-200iP manufactured by Samco Co., Ltd.), a mixed gas of chlorine (Cl ₂ ) and silicon tetrachloride (SiCl ₄ ) is used as a reaction gas, pressure 1 Pa, bias output / The ITO film is dry-etched for 5 minutes under the condition of ICP output = 200/100 (W). By this dry etching process, a recess 16 penetrating the transparent electrode layer 12 and the photoresist layer is formed. The recesses 16 have a cylindrical shape with a diameter of 0.5 μm, and are arranged in a hexagonal lattice pattern with a period of 1 μm on the entire surface of the transparent electrode layer 12.

Next, spin-on-glass (SOG) (manufactured by AZ Electronic Materials Co., Ltd., Aquamica (registered trademark) NL120A-10, refractive index 1.4) is spinned as a dielectric material inside the recess 16 and on the top of the photoresist layer. A coating film is formed by a coating method, and is dried by heating at 250 ° C for 30 minutes. Next, using a reactive ion etching apparatus, CHF ₃ is used as a reaction gas, and the reaction is performed for 1 minute under the conditions of pressure 0.3 Pa, bias output / ICP output = 50/100 (W), and then a photoresist. The photoresist layer and the SOG layer above the photoresist layer are removed with a removing solution. As a result, the recess 16 formed in the transparent electrode layer 12 is filled, and the dielectric layer 13 made of SOG protruding from the top of the recess 16 by 80 nm from the upper surface of the transparent electrode layer 12 is formed. The dielectric layer 13 has a cylindrical shape with a diameter of 0.5 μm, and is arranged in a hexagonal lattice pattern with a period of 1 μm on the entire surface of the transparent electrode layer 12.

  Next, in the vacuum deposition apparatus, a hole transport layer (not shown), a light emitting layer (not shown), and an electron transport layer (shown in the figure) are formed on the top surface of the transparent electrode layer 12 and the top surface of the dielectric layer 13 made of SOG. The organic layer 14 (refractive index 1.7) formed by laminating in this order is formed. First, a compound 1 shown below is formed by vacuum vapor deposition to form a 20 nm hole transport layer. Further, a compound 2 and a compound 3 are co-evaporated on the hole transport layer at a mass ratio of 10:90 to form a light emitting layer having a thickness of 20 nm, and then a compound 4 is deposited on the light emitting layer. Then, an electron transport layer having a thickness of 20 nm is formed. The thickness of the organic layer 14 is 60 nm.

  Next, on the organic layer 14, sodium fluoride (4 nm) as a cathode buffer layer and aluminum (150 nm) as a metal electrode layer 15 are sequentially formed by a vacuum evaporation method to produce an organic light emitting device.

The cross section of the produced organic light emitting device is observed with an electron microscope. In this embodiment, the side surface of the dielectric layer 13 made of SOG and the metal electrode layer 15 are substantially in contact with each other in the range of 20 nm from the top of the dielectric layer 13. In addition, the emission intensity of the organic light emitting device was determined by applying a voltage stepwise to the organic light emitting device using a constant voltage power supply ammeter (SM2400 manufactured by Keithley Instruments Co., Ltd.) and a luminance meter (BM-9 manufactured by Topcon Co., Ltd.). Measure by
In this example, the external light emission quantum efficiency obtained from the ratio of the light emission intensity to the current density of the produced organic light emitting device is 11.4%.

(Example 2)
An organic light emitting device having the cross-sectional structure shown in FIG. 8B is manufactured, and then the light emission intensity is measured.
First, an ITO film (thickness 120 nm) is formed as a transparent electrode layer 12 on the substrate 11 by the same operation as in Example 1, and then a photoresist layer is formed, and the same pattern as in Example 1 is formed on the photoresist layer. Form.

  Next, using a reactive ion etching apparatus, an argon gas is used as an etching gas, and a dry etching process of the ITO film is performed for 5 minutes under the conditions of pressure 1 Pa and bias output / ICP output = 200/100 (W). By this dry etching process, a recess 162 penetrating the transparent electrode layer 12 and the photoresist layer is formed. The cross-sectional shape of the recesses 162 is a truncated cone shape in which the upper surface side of the photoresist layer extends in a taper shape, and is arranged in a hexagonal lattice pattern with a period of 1 μm on the entire surface of the transparent electrode layer 12.

Next, SOG is applied by spin coating to the inside of the recess 162 and the upper part of the photoresist layer by the spin coat method, and is heated and dried at 250 ° C. for 30 minutes. Next, using a reactive ion etching apparatus, CHF ₃ is used as a reaction gas, and the reaction is performed for 1 minute under the conditions of pressure 0.3 Pa, bias output / ICP output = 50/100 (W), and then a photoresist. The photoresist layer and the SOG layer above the photoresist layer are removed with a removing solution. Thereby, the dielectric layer 13 made of SOG is formed in which the concave portion 162 formed in the transparent electrode layer 12 is filled, and the convex portion 132 having a height of 80 nm protrudes from the upper surface of the concave electrode 162 from the upper surface of the transparent electrode layer 12. The cross-sectional shape of the dielectric layer 13 is a frustoconical shape with the upper part widened, the diameter of the upper circle is 0.63 μm, the diameter of the lower circle is 0.40 μm, and 1 μm on the entire surface of the transparent electrode layer 12. Are arranged in a hexagonal lattice pattern.
The cross-sectional shape of the dielectric layer 13 with respect to the plane perpendicular to the surface of the transparent electrode layer 12 is an isosceles trapezoid whose upper part is widened, and the inner angle (taper angle) formed by the side of the trapezoid and the upper base. Is about 60 °.

Next, in the same manner as in Example 1, an organic layer 14, a cathode buffer layer (not shown), and a metal electrode layer 15 are laminated in this order to produce an organic light emitting device.
As in Example 1, the cross section of the produced organic light emitting device is observed with an electron microscope. In this embodiment, the side surface of the dielectric layer 13 made of SOG and the metal electrode layer 15 are substantially in contact with each other in the range of 10 nm from the top of the dielectric layer 13.
Further, in this example, the external light emission quantum efficiency obtained from the ratio of the light emission intensity to the current density of the produced organic light emitting device is 14.9%.

(Comparative Example 1)
In the cross-sectional structure shown in FIG. 2C described above, an organic light emitting device (FIG. 15) that does not have the convex portion 131 of the dielectric layer 13 is manufactured, and thereafter the emission intensity is measured.
FIG. 15 is a diagram illustrating an organic light emitting device fabricated in Comparative Example 1. The same components as those in FIG. 2C are denoted by the same reference numerals, and the description thereof is omitted.
First, an ITO film (thickness 120 nm) is formed as a transparent electrode layer 12 on the substrate 11 by the same operation as in Example 1, and then a photoresist layer is formed, and the same pattern as in Example 1 is formed on the photoresist layer. Form.

Next, using a reactive ion etching apparatus, a mixed gas of chlorine (Cl ₂ ) and silicon tetrachloride (SiCl ₄ ) is used as a reaction gas, pressure 1 Pa, bias output / ICP output = 200/100 (W) The ITO film is dry-etched for 5 minutes under the above conditions. Next, when the photoresist layer is removed with a photoresist removing solution, a recess 16 penetrating the transparent electrode layer 12 is formed. The recesses 16 have a cylindrical shape with a diameter of 0.5 μm, and are arranged in a hexagonal lattice pattern with a period of 1 μm on the entire surface of the transparent electrode layer 12.

Next, SOG is applied and formed on the entire surface of the transparent electrode layer 12 with the recesses 16 by spin coating, as in Example 1, and heated and dried at 250 ° C. for 30 minutes. An SOG layer is formed on the layer 12. Next, using a reactive ion etching apparatus, CHF ₃ is used as a reaction gas, and the reaction is performed for 2 minutes under the conditions of pressure 0.3 Pa, bias output / ICP output = 50/100 (W), and the transparent electrode layer 12 To expose. Thereby, the transparent electrode layer 12 in which the concave portion 16 is filled with the dielectric layer 13 made of SOG is formed.

Subsequently, the organic layer 14, the cathode buffer layer (not shown), and the metal electrode layer 15 are sequentially laminated in the same manner as in Example 1 to produce an organic light emitting device. The cross-sectional structure of the organic light-emitting device in this comparative example, as observed by an electron microscope, is filled with SOG in the concave portion 16 of the transparent electrode layer 12 and does not have a convex portion protruding toward the organic layer 14 side.
Moreover, in this comparative example, the external light emission quantum efficiency calculated | required from the ratio of the emitted light intensity with respect to the current density of the produced organic light emitting element is only 8.0%.

(Comparative Example 2)
In the cross-sectional structure shown in FIG. 2C described above, the transparent electrode layer 12 has a flat structure (the recess 16 is not formed), and an upper portion 136 of the dielectric layer 13 formed on the transparent electrode layer 12 is Then, an organic light emitting device (FIG. 16) is produced so that the metal layer protrudes from the surface of the organic layer 14 and a part of the side surface and the upper surface of the dielectric layer 13 are in contact with the metal electrode layer 15.
FIG. 16 is a diagram illustrating an organic light-emitting device manufactured in Comparative Example 2. The same components as those in FIG. 2C are denoted by the same reference numerals, and the description thereof is omitted.
First, an ITO film (thickness 120 nm) is formed as a transparent electrode layer 12 on the substrate 11 by the same operation as in Example 1, and then a photoresist layer is formed, and the same pattern as in Example 1 is formed on the photoresist layer. Form.

Next, SOG is applied and formed on the entire surface of the photoresist layer on which the pattern has been formed by spin coating as in Example 1, and is heated and dried at 250 ° C. for 30 minutes. Next, using a reactive ion etching apparatus, using CHF ₃ as a reaction gas, the reaction is performed for 2 minutes under the conditions of pressure 0.3 Pa, bias output / ICP output = 50/100 (W), and dry etching processing is performed. . Next, the dielectric layer 13 made of SOG is formed on the transparent electrode layer 12 by removing the photoresist layer with a photoresist removing solution. The dielectric layer 13 has a cylindrical shape with a diameter of 0.5 μm and a height of 80 nm, and is arranged in a hexagonal lattice pattern with a period of 1 μm on the entire surface of the transparent electrode layer 12.

Next, the organic layer 14, the cathode buffer layer (not shown), and the metal electrode layer 15 are laminated in this order by the same operation as in Example 1 to produce an organic light emitting device.
In the cross-sectional structure of the organic light-emitting element in this comparative example observed by an electron microscope, the side surface of the dielectric layer 13 made of SOG and the metal electrode layer 15 are in contact with each other in the range of 20 nm from the top of the dielectric layer 13.
Moreover, in this comparative example, the external light emission quantum efficiency calculated | required from the ratio of the emitted light intensity with respect to the current density of the produced organic light emitting element is only 6.1%.

100, 101, 102, 200, 300, 400 ... organic light emitting element, 11 ... substrate, 12 ... transparent electrode layer, 13, 134 ... dielectric layer, 13A, 13B ... interface, 14 ... organic layer, 15 ... metal electrode layer , 21 ... Photoresist layer, 16, 162, 165 ... Recess, 131, 132, 133 ... Projection, 135 ... Dielectric material layer, 136 ... Upper part, 140 ... Light emitting point (light emitting point), 145 ... Light emitting layer, 150 , 151, A, B ... light

Claims (11)

An organic light emitting device comprising a transparent electrode layer, an organic layer including a light emitting layer, at least the transparent electrode layer and a dielectric layer in contact with the organic layer, and a metal electrode layer,
The laminate composed of the transparent electrode layer and the organic layer and the dielectric layer form a sea-island structure in a plane including the dielectric layer and the laminate,
When the direction of the metal electrode layer is the upper side in the vertical cross section of the organic light emitting device, the uppermost position on the upper surface of the dielectric layer is on the upper surface of the light emitting layer in the organic layer on the transparent electrode. Located above the lowest position,
The refractive index n ₁ of the dielectric layer is smaller than the refractive index n _{2 of the} organic layer (n ₁ <n ₂ ) and smaller than the refractive index n ₃ of the transparent electrode layer (n ₁ <n ₃ ).
An organic light emitting device characterized by that.   2. The organic light emitting device according to claim 1, wherein the uppermost position on the upper surface of the dielectric layer is located above the lowermost position on the upper surface of the organic layer on the transparent electrode layer.   The organic light-emitting device according to claim 1, wherein at least a part of the dielectric layer is in contact with the metal electrode layer.   4. The shape according to claim 1, wherein the shape of the island portion in the sea-island structure is any one of a cylinder, a truncated cone, and an inverted truncated cone having an element surface normal direction as an axis. Organic light emitting device.   In the sea-island structure, the dielectric layer forms the island part, and the island part is formed in a columnar shape or an inverted truncated cone shape that tapers toward the transparent electrode layer side. The organic light emitting device according to claim 4.   6. The organic light emitting device according to claim 5, wherein an inner angle formed between a side surface of the island portion and a bottom surface of the island portion on the metal electrode layer side is 40 ° to 90 °.   The organic island forms the island part in the sea-island structure, and the island part is formed in a circular truncated cone shape or a truncated cone shape that tapers toward the metal electrode layer side. 4. The organic light emitting device according to 4.   The organic light-emitting device according to claim 7, wherein an inner angle formed by a side surface of the island portion and a bottom surface of the island portion on the transparent electrode layer side is 40 ° to 90 °. In the sea-island structure, the island portion has a maximum width e of 10 μm or less (e ≦ 10 μm), and 102 ² to 10 ⁸ island portions are formed per 1 mm square on the upper surface of the transparent electrode layer. The organic light-emitting device according to claim 1, wherein the organic light-emitting device is a light-emitting device.   The organic light-emitting element according to claim 1, further comprising a substrate on a side of the transparent electrode layer opposite to the organic layer.   The organic light-emitting element according to claim 1, further comprising a substrate on a side of the metal electrode layer opposite to the organic layer.

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