WO2014084209A1

WO2014084209A1 - Organic light emitting element, method for manufacturing organic light emitting element, display device and lighting device

Info

Publication number: WO2014084209A1
Application number: PCT/JP2013/081781
Authority: WO
Inventors: 白根　浩朗
Original assignee: 昭和電工株式会社
Priority date: 2012-11-27
Filing date: 2013-11-26
Publication date: 2014-06-05

Abstract

An organic light emitting element (10) which is characterized by being provided with: a positive electrode layer (12) that is formed on a substrate (11); an insulating low-refractive-index layer (13) that is formed on the positive electrode layer (12); a hole (17) that is formed so as to penetrate through at least the low-refractive-index layer (13); a light transmitting conductive layer (14) that is formed only along the entire bottom surface of the hole (17) or at least along the entire bottom surface and the lateral surface of the hole (17), and is electrically connected to the positive electrode layer (12); an organic semiconductor layer (15) that contains a light emitting layer (15a) and is formed on the light transmitting conductive layer (14) such that at least a part of the organic semiconductor layer (15) enters into the hole (17); and a negative electrode layer (16) that is formed on the organic semiconductor layer (15). The organic light emitting element (10) is also characterized in that: the low-refractive-index layer (13) has a lower refractive index than the light transmitting conductive layer (14) and the organic semiconductor layer (15); the hole (17) has a maximum width of 3 μm or less when viewed in plan; and the organic semiconductor layer (15) is formed to have a uniform thickness at a position where the hole (17) is formed.

Description

ORGANIC LIGHT EMITTING ELEMENT, METHOD FOR PRODUCING ORGANIC LIGHT EMITTING ELEMENT, DISPLAY DEVICE AND LIGHTING DEVICE

The present invention relates to, for example, an organic light emitting element used for a display device or a lighting device.

As shown in FIG. 19, a typical structure of the organic light emitting element is formed by sequentially laminating a transparent first electrode 112, an organic layer 115 including a light emitting layer, and a reflective second electrode 116 on a transparent substrate 111. Structure. Here, typical refractive indexes of the respective layers are, for example, 1.5 for the transparent substrate 111, 1.9 for the first transparent electrode 112, and 1.7 for the organic layer 115. In such a laminated structure, at the interface where the refractive index changes from high to low along the light traveling direction, the incident angle (the angle formed between the incident ray and the normal of the incident interface) is the critical angle. The above light cannot be totally reflected and transmitted through the interface.

By the way, when light travels from a medium having a refractive index of n _{1 to} a medium having a refractive index of n ₂ , the angle between the incident angle θ ₁ and the outgoing angle θ ₂ with respect to the normal of the interface is expressed by the equation (1). Snell's law,
sin θ ₁ / sin θ ₂ = n ₂ / n ₁ (1)
Holds. The critical angle θ _{cr at} which total reflection occurs is an incident angle when the emission angle θ ₂ is 90 °, and is expressed by the equation (2).
θ _cr = sin ⁻¹ (n ₂ / n ₁ ) (2)

In the organic light emitting device 100 shown in FIG. 19, total reflection occurs at the transparent substrate 111 / air interface and the translucent first electrode 112 / transparent substrate 111 interface. Here, when the refractive index of each layer is the above representative value, the critical angles at these interfaces are 42 ° and 52 °, respectively. FIG. 19 shows how light travels differently depending on the emission angle of light emitted from the light emission position P in the organic layer 115 (the angle with respect to the normal to the substrate plane). Here, light having a radiation angle of 36 ° from the light emission position P corresponds to light having an incident angle at the light-transmitting transparent substrate 111 / air interface having a critical angle (42 °). In addition, light having an emission angle of 62 ° from the light emission position P corresponds to light having an incident angle at the interface of the translucent first electrode 112 / substrate 111 that is a critical angle (52 °). Accordingly, light having a radiation angle from the light emission position P of 36 ° or less (for example, the light beam L1 and the radiation angle 30 °) is transmitted from the transparent substrate 111 to the outside. However, light having a radiation angle from 36 ° to 62 ° from the light emission position P (for example, light ray L2, radiation angle 40 °) is confined between the outer surface of the transparent substrate 111 and the interface between the organic layer 115 and the second electrode 116. It becomes a guided mode. In addition, light having a radiation angle of 62 ° or more from the light emission position P (for example, light beam L3, radiation angle 70 °) is a translucent first electrode 112 / substrate 111 interface and an organic layer 115 / second electrode 116 interface. It becomes a waveguide mode confined between.

As described above, in the configuration of the general organic light emitting device 100, most of the light generated in the light emitting layer is confined in the device by total reflection, and about 20% of the light extracted outside is known. It has been.

In order to improve the light extraction efficiency, it is necessary to reduce the total reflected light, and many attempts have been made for this purpose (see, for example, Patent Documents 1 to 7).

JP 2003-036969 A JP 2002-260845 A JP-A-11-214162 Japanese Patent Laid-Open No. 2001-230069 Special table 2010-509729 Special table 2010-524153 JP 2004-311419 A

The present invention has been made in view of the above-described problems of conventional techniques.
That is, an object of the present invention is directed to an organic light-emitting device that suppresses total reflection by changing a light distribution of light generated in a light-emitting layer, and has high light extraction efficiency and excellent durability. It is to provide an element or the like.

Thus, the organic light emitting device of the present invention is formed through the first electrode layer formed on the substrate, the insulating low refractive index layer formed on the first electrode layer, and at least the low refractive index layer. A light-transmitting conductive layer formed along only the entire bottom surface of the hole portion, or at least along the entire bottom surface and side surfaces of the hole portion and in electrical contact with the first electrode layer, and a light emitting layer An organic semiconductor layer formed on the translucent conductive layer and formed so that at least a part of the hole enters the inside of the hole, and a second electrode layer formed on the organic semiconductor layer, The low refractive index layer has a refractive index smaller than that of the light-transmitting conductive layer and the organic semiconductor layer, and has a maximum width of 3 μm or less when the hole is viewed in plan. The organic semiconductor layer is located at the position where the hole is formed. It is characterized by being formed with a uniform thickness.

Here, the light emitting layer of the organic semiconductor layer is preferably formed so that at least part of the light emitting layer enters the inside of the hole, and the surface of the translucent conductive layer on the organic semiconductor layer side is a position where the hole is formed. It is preferable to make a shape that is recessed toward the first electrode layer, and it is more preferable that the shape that is recessed toward the first electrode layer is a curved surface.
The translucent conductive layer is preferably formed to extend on the low refractive index layer, and the translucent conductive layer is preferably formed with a uniform thickness along the inner surface of the hole. .
The first electrode layer may reflect light emitted from the light emitting layer of the organic semiconductor layer, the second electrode layer may transmit light emitted from the light emitting layer, and the first electrode layer may be organic semiconductor. The light emitted from the light emitting layer may be transmitted, and the second electrode layer may reflect the light emitted from the light emitting layer.
Furthermore, the hole is preferably formed by further drilling at least a part of the first electrode layer, and the hole is preferably formed by further drilling a part of the substrate.

The method for producing an organic light emitting device of the present invention includes a first electrode layer forming step for forming a first electrode layer on a substrate, and a low refractive index layer for forming an insulating low refractive index layer on the first electrode layer. A forming step, a hole forming step of forming a hole having a maximum width of 3 μm or less penetrating at least through the low refractive index layer, and being formed at least inside the hole and the first electrode layer, An organic semiconductor including a light-transmitting conductive layer forming step of forming a light-transmitting conductive layer that is in electrical contact by a coating method, and a light-emitting layer on the light-transmitting conductive layer so that at least a part of the light-transmitting conductive layer enters inside the hole An organic semiconductor layer layer forming step for forming a layer, and a second electrode layer forming step for forming a second electrode layer on the organic semiconductor layer, wherein the low refractive index layer comprises a light-transmitting conductive layer and an organic semiconductor layer It is characterized by a lower refractive index.

The display device of the present invention includes the above organic light emitting element.

The lighting device of the present invention includes the above organic light emitting element.

According to the present invention, it is possible to provide an organic light emitting device having high light extraction efficiency and excellent durability.

It is the fragmentary sectional view explaining the 1st example of the organic light emitting element to which this Embodiment is applied. It is the figure which showed an example in case a light emitting layer does not enter inside a hole part. It is the figure which showed the example of a measurement of the film thickness of an organic-semiconductor layer. (A)-(b) is the figure explaining the example of arrangement | positioning of the hole part seen from the upper side on which each layer which comprises an organic light emitting element is laminated | stacked. It is a fragmentary sectional view explaining the 2nd example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 3rd example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 4th example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 5th example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 6th example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 7th example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 8th example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 9th example of the organic light emitting element to which this Embodiment is applied. It is the fragmentary sectional view explaining the 10th example of the organic light emitting element to which this Embodiment is applied. It is a fragmentary sectional view explaining the 11th example of the organic light emitting element to which this Embodiment is applied. It is a fragmentary sectional view explaining the 12th example of the organic light emitting element to which this Embodiment is applied. It is a fragmentary sectional view explaining the 13th example of the organic light emitting element to which this embodiment is applied. It is the fragmentary sectional view explaining the 14th example of the organic light emitting element to which this Embodiment is applied. It is the figure explaining the light extraction in the organic light emitting element of a prior art. It is the figure explaining the light extraction by the low refractive index layer in the organic light emitting element to which this Embodiment is applied. (A)-(f) is a figure explaining the manufacturing method of the organic light emitting element to which this Embodiment is applied. It is a figure explaining an example of the display apparatus using the organic light emitting element in this Embodiment. It is a figure explaining an example of an illuminating device provided with the organic light emitting element in embodiment. It is the figure explaining the light extraction in the organic light emitting element of a prior art. It is an example of the first prior art, and is a diagram illustrating an organic light emitting device in which a light emitting side surface is processed into an uneven shape. It is a figure explaining the organic light emitting element of the prior art. It is a figure explaining the organic light emitting element of the prior art.

As a first conventional technique for improving the light extraction efficiency, there is a method in which a flat interface where total reflection occurs is processed to make the flat surface less likely to cause total reflection. Examples of the first conventional technique include those obtained by processing the light emitting side surface of the organic light-emitting element into a concavo-convex shape as exemplified in Patent Document 1 (Prior Art 1-1) and those described in Patent Document 2. An organic light emitting device having a microlens on the light emitting side surface is mentioned (conventional technology 1-2). With these methods, light that could not be extracted to the outside can be extracted. However, when the interface is a flat surface, a part of the light extracted to the outside is not extracted, and a great improvement in light extraction efficiency cannot be obtained.

FIG. 20 is a diagram illustrating an organic light-emitting element that is an example of the first prior art and has a light emitting side surface processed into a concavo-convex shape.
The organic light emitting device 100 has the same configuration as the organic light emitting device 100 shown in FIG. 19 except that the outer surface of the transparent substrate 111 has a concavo-convex structure having a slope of 45 °. Here, in the case of the organic light emitting device 100 of FIG. 19, the light beam L2 emitted from the light emission position P is totally reflected on the outer surface of the transparent substrate 111, but the light of the organic light emitting device 100 of FIG. In this case, the light is incident on the inclined surface having an inclination angle of 45 ° on the outer surface of the transparent substrate 111 and transmitted therethrough. However, the light beam L4 emitted from the light emission position P at an emission angle of 0 ° is extracted by the organic light emitting device 100 of FIG. 19, but 45 ° with respect to the slope of the outer surface of the transparent substrate 111 in the organic light emitting device 100 of FIG. Since it is incident at an incident angle of 1, it is totally reflected and is not taken out to the outside.

As a second conventional technique for improving the light extraction efficiency with respect to the problems of the first conventional technique, the interface causing total reflection is left flat and the light distribution of light incident on this interface is distributed. There is a method of increasing the light whose incident angle to the interface is smaller than the critical angle by changing. A specific method is illustrated below.

For example, there is a technique exemplified in Patent Document 3 described above, in which a minute protrusion is provided on an electrode located on the light emission surface side, thereby imparting a concave shape to the counter electrode (conventional technique 2-1). Since the traveling direction of light changes due to the reflection on the concave inclined mirror surface of the counter electrode, the light extraction efficiency is easily improved.

Moreover, the technique of forming the diffraction grating which consists of SiO which has a periodic structure in the direction parallel to a substrate surface between the organic thin film layer and the electrode of the light emission side illustrated by the said patent document 4 is mentioned (conventionally). Technology 2-2). With this periodic structure, light emitted from the light-emitting layer in the direction close to the horizontal direction (in-plane direction of the substrate) is efficiently extracted to the outside and the light emission efficiency is easily improved.

Furthermore, there is a cavity electroluminescent device exemplified in the above-mentioned Patent Document 5 in which a cavity penetrating a dielectric layer is provided and an organic layer is filled in the cavity for the purpose of increasing the area of the light emitting region relative to the device area ( Conventional technique 2-3). In Patent Document 5, the refractive index of the dielectric layer is not mentioned, but the use of a material (such as silicon oxide) having a lower refractive index than the organic layer is also disclosed. Therefore, the cavity electroluminescent device disclosed in Patent Document 5 has the light extraction effect disclosed in Patent Document 6 described later when a material having a lower refractive index than the organic layer is used as the material of the dielectric layer. It is thought to have.

Furthermore, there is a technique of providing a transparent material region having a lower refractive index in a region including an organic light emitting material between two electrodes, as exemplified in Patent Document 6 (Prior Art 2-4). The presence of this low refractive index region makes it easy to refract and extract light that is not extracted and enters the low refractive index region when it does not exist.

Furthermore, a technique exemplified by the above-mentioned Patent Document 7 is provided with mode conversion means for converting from the waveguide mode to the radiation mode in order to extract light that is confined as a waveguide mode in the light emitting element and is not extracted to the outside. (Prior art 2-5). This mode conversion means is formed with a periodic structure having a refractive index that prohibits propagation of light in a waveguide mode.

However, in the organic light emitting devices of the conventional technology 2-1 and the conventional technology 2-2 among the above, light that could not be extracted to the outside can be extracted, but light distribution such as a concave reflecting surface or a diffraction grating is possible. When there is no means for changing the distribution, a part of the light extracted to the outside is not extracted, and a great improvement in light extraction efficiency cannot be obtained.

In addition, the above-described conventional techniques 2-3 to 2-5 are extracted to the outside when there is no means for changing the light distribution as seen in the conventional techniques 2-1 and 2-2. While the problem that a part of the light that has been lost cannot be extracted is considerably solved, the following new problem arises.
That is, in the cavity electroluminescent device disclosed in Patent Document 5 which is an example of the prior art 2-3, the film thickness of the organic layer is not uniform due to the uneven structure when the organic layer is actually formed. It is easy to become. Hereinafter, specific examples will be described.

In the organic light emitting device 100 shown in FIG. 21A, an anode layer 122 and a dielectric layer 123 are sequentially laminated on a substrate 121, and a plurality of holes (cavities) 127 penetrating through the dielectric layer 123 are formed. Has been. Then, an organic layer 125 including a light emitting layer is formed thereon. Here, as disclosed in Patent Document 5, when a polymer material is formed as an organic layer 125 by coating, the organic layer 125 is formed into a shape that falls into the hole 127. The cathode layer 126 formed thereon is also formed in a shape along the drop of the organic layer 125.

When the organic layer 125 is formed with a non-uniform thickness between the anode layer 122 and the cathode layer 126 in this way, the current flows in the center portion (C1) of the hole portion 127 where the distance between the electrodes is the shortest. Flow part). Accordingly, the organic light emitting device 100 shown in FIG. 21A emits light only in the vicinity of the center of the hole 127, and the utilization efficiency of the light emitting material in the hole 127 is low, and as a result, high luminance cannot be achieved. Furthermore, since the deterioration locally proceeds in the portion where the current flows in a concentrated manner, the durability of the organic light emitting device 100 is likely to be lowered.

On the other hand, the organic light emitting device 100 shown in FIG. 21-2 is different from the organic light emitting device 100 shown in FIG. 21-1 only in that the hole 127 penetrates not only the dielectric layer 123 but also the anode layer 122. In this case as well, the organic layer 125 is formed into a shape that falls into the hole 127.
In the organic light emitting device 100 of FIG. 21-2, in addition to the non-uniform thickness of the organic layer 125, the anode layer 122 is in contact with the organic layer 125 at the end face. As a result, the current flows in the vicinity of the side surface of the hole 127 (portion C2). Accordingly, the organic light emitting device 100 shown in FIG. 21-2 emits light only in the vicinity of the side surface of the hole 127, and high luminance cannot be achieved like the organic light emitting device 100 shown in FIG. It is easy to deteriorate.

Further, in the organic light emitting device 100 exemplified in Patent Document 5, it is important to dispose the light emitting layer (light emitting position) in the hole 127 particularly when the refractive index of the dielectric layer 123 is smaller than the organic layer 125. Conceivable. However, Patent Document 5 does not disclose any relative positional relationship between the light emitting layer (light emitting position) in the organic layer 125 and the hole 127.

Furthermore, in the organic light-emitting device having a low refractive index region disclosed in Patent Document 6 as an example of the prior art 2-4, a hexagonal grid or a rectangular grid (low refractive index) in a plane parallel to the substrate. The area is arranged in a repeating pattern such as a grid frame part). Here, the dimension of the organic light emitting region inside the grid is disclosed as 4 μm to 10 μm. Since the extinction coefficient of the organic light emitting layer material is generally about 0.01 to 0.1, assuming that light with a wavelength of 555 nm (maximum visibility) travels 4 μm, the light intensity has an extinction coefficient of 0. In the case of .01, it attenuates to the original 0.01%, and when the extinction coefficient is 0.1, it attenuates to the original 40%. Therefore, in the organic light emitting device having the structure disclosed in Patent Document 6, it is assumed that most of the guided light is attenuated before entering the low refractive index region, and the light extraction effect by the low refractive index region is not sufficiently exhibited. .

Patent Document 6 discloses that a cavity electroluminescent element can have a structure in which a plurality of organic layers are stacked in parallel with a substrate as an organic light emitting region (the thickness of each layer is uniform). . However, a specific method for actually realizing this is not shown.

Further, the mode conversion means of the organic light emitting device disclosed in Patent Document 7 which is an example of the prior art 2-5 has a refractive index periodic structure that prohibits the propagation of light in a waveguide mode. It is based on the principle of so-called photonic crystals. As a structure of this photonic crystal, a fine periodic structure whose refractive index changes with a period of about the effective wavelength of light (emission wavelength / medium refractive index: submicron order) is necessary. However, it is extremely difficult to process such a submicron structure with the strict dimensional accuracy required for the function of the photonic crystal. Therefore, it is not easy to manufacture an organic light emitting device that uses a photonic crystal and has high light extraction efficiency. Even if a periodic structure that functions as a photonic crystal can be manufactured, the thickness of the organic layer when the organic layer is formed on the concavo-convex portion is the same as in the case of the organic light emitting device disclosed in Patent Document 5. There is a problem that it tends to be non-uniform. Further, Patent Document 7 does not disclose any relative positional relationship between the light emitting layer (light emitting position) in the organic layer and the concavo-convex structure.

As described above, in the organic light emitting devices of the conventional technology 2-3 to the conventional technology 2-5, the organic layer has a uniform thickness in the concave portion of the concavo-convex structure that changes the light distribution of the light generated in the light emitting layer. There is no disclosure of a film formation and a configuration that allows light emitted from the organic light emitting region to be extracted into the low refractive index region before being attenuated in the organic light emitting region.

Inventing the present invention, the inventors paid attention to the following points in a conventional organic light emitting device having a cavity and a low refractive index layer. That is, in the organic light emitting device of the prior art, in order to improve the light extraction efficiency, the base surface on which the organic layer is formed has cavities and irregularities due to regions having a refractive index different from that of the organic layer. The organic layer and the upper electrode (electrode on the side away from the substrate) are formed in the recess. Therefore, the distance between the upper electrode and the lower electrode (substrate-side electrode) is not uniform. It was considered that this caused non-uniform light emission, the light extraction efficiency was lowered, and the life was shortened. In view of this, the inventors have formed the cavity inner surface in order to make the gap between the upper electrode and the lower electrode uniform without changing the inner surface of the cavity (interface having different refractive indexes) involved in light extraction. The inventors have conceived that a substantial lower electrode surface is provided separately from the side electrode surface, and have completed the present invention.

In the organic light emitting device of the prior art having the above-described cavity and low refractive index layer, both the lower electrode surface and the refractive index interface that refracts light emitted from the light emitting layer in a direction in which it is easily extracted to the outside are provided on the inner surface of the cavity. Exists. On the other hand, the present embodiment is characterized in that the lower electrode surface is separated from the cavity inner surface. That is, by forming a translucent conductive layer having the same refractive index as the organic layer in contact with the lower electrode exposed on the inner surface of the cavity, the refractive index interface remains on the inner surface of the cavity, but the surface of the translucent conductive layer Becomes a substantial lower electrode surface. Here, by controlling the formation position of the light-transmitting conductive layer in the cavity (the position of the interface between the light-transmitting conductive layer and the organic layer), the light emitting layer is optimized to a position where the light extraction efficiency is high in the cavity. The Further, uniform light emission in the cavity can be obtained by making the surface shape of the translucent conductive layer so that the film thickness of the organic layer formed thereon is likely to be uniform.

In the organic light emitting device of the present embodiment, either the upper electrode or the lower electrode may be an anode or a cathode. In addition, at least one of the electrodes may be translucent. Hereinafter, specific embodiments of the present invention will be described.

[Organic light emitting device in which lower electrode is translucent anode layer]
(Organic light emitting device)
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1-1 is a partial cross-sectional view illustrating a first example of an organic light emitting device to which the present embodiment is applied. The actual organic light emitting element 10 takes a form in which this structure is repeated in the horizontal direction in the figure.
1-1 includes a substrate 11, an anode layer 12 formed on the substrate 11 as a first electrode layer for injecting holes, and a second electrode for injecting electrons. A structure in which a cathode layer 16 as a layer and an insulating low refractive index layer 13 formed between the anode layer 12 and the cathode layer 16 are laminated is adopted. Here, the anode layer 12 is translucent, and light is extracted from the substrate 11 side.

The organic light emitting device 10 has a hole 17 formed so as to penetrate at least the low refractive index layer 13. Further, the organic light emitting element 10 includes a light transmissive conductive layer 14 and an organic semiconductor layer 15. The translucent conductive layer 14 is formed in the hole 17 and is in electrical contact with the anode layer 12. The organic semiconductor layer 15 includes the light emitting layer 15 a, is formed on the translucent conductive layer 14, and is formed so that at least a part thereof enters the hole 17.

The organic light emitting element 10 forms a light emitting surface when the light emitting layer 15a of the organic semiconductor layer 15 emits light. In the present embodiment, the translucent conductive layer 14 and the organic semiconductor layer 15 are formed not only at the positions of the holes 17 but also extending on the low refractive index layer 13. Therefore, the cathode layer 16 is formed so as to be located on the organic semiconductor layer 15 over the entire surface of the organic semiconductor layer 15. In the present embodiment, “the position of the hole portion 17” and “the position where the hole portion 17 is formed” mean the position of the hole portion 17 as viewed from the upper side where the above layers are stacked. Shall.

(substrate)
The substrate 11 serves as a support for forming the anode layer 12, the low refractive index layer 13, the translucent conductive layer 14, the organic semiconductor layer 15, and the cathode layer 16. A material that satisfies the mechanical strength required for the organic light emitting device 10 is used for the substrate 11.

As the material of the substrate 11, when light is extracted from the substrate 11 side of the organic light emitting element 10 as in the first example, it is necessary to be light transmissive with respect to the light emitted from the light emitting layer 15 a. Specific materials include: glass such as sapphire glass, soda glass, and quartz glass; transparent resin such as acrylic resin, methacrylic resin, polycarbonate resin, polyester resin, nylon resin, and silicone resin; metal nitride such as aluminum nitride, Examples thereof include transparent metal oxides such as alumina. In addition, when using the resin film etc. which consist of the said transparent resin as the board | substrate 11, it is preferable that the gas permeability with respect to gas, such as water and oxygen, is low. When using a resin film or the like having high gas permeability, it is preferable to form a barrier thin film that suppresses gas permeation as long as light permeability is not impaired.

The thickness of the substrate 11 is preferably 0.1 mm to 10 mm, more preferably 0.25 mm to 2 mm, although it depends on the required mechanical strength.

(Anode layer)
The anode layer 12 injects holes into the organic semiconductor layer 15 by applying a voltage between the anode layer 12 and the cathode layer 16. In the first example, since light is extracted from the substrate 11 side, the material of the anode layer 12 needs to be light transmissive with respect to the light emitted from the light emitting layer 15a. Further, the anode layer 12 is preferably formed in a planar shape along the substrate 11 and the upper surface is a smooth surface that contains as little as possible fine irregularities. The material used for the anode layer 12 needs to have electrical conductivity. Specifically, it has a high work function, and the work function is preferably 4.5 eV or more. In addition, it is preferable that the electrical resistance does not change significantly with respect to the alkaline aqueous solution.

A light-transmitting metal oxide can be used as a material satisfying such conditions. Specific examples of the compound include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide. The anode layer 12 can be formed with a thickness of 2 nm to 2 μm, for example. The work function can be measured by, for example, ultraviolet photoelectron spectroscopy.

(Low refractive index layer)
The low refractive index layer 13 is for making it easy to be extracted outside by refracting light emitted from the organic semiconductor layer 15. Therefore, the low refractive index layer 13 has a refractive index lower than that of the translucent conductive layer 14 and the organic semiconductor layer 15. More specifically, the refractive index of the low refractive index layer 13 is preferably 0.1 or more smaller than the refractive indexes of the translucent conductive layer 14 and the organic semiconductor layer 15, more preferably 0.2 or smaller. More preferably, it is smaller than 0.3.

Then, by making the refractive index of the low refractive index layer 13 lower than the refractive indexes of the translucent conductive layer 14 and the organic semiconductor layer 15, light L1 emitted from the organic semiconductor layer 15 (of the low refractive index layer 13 and the hole portion 17). In a conventional organic light-emitting device having no conventional structure, light that undergoes total internal reflection and is not extracted to the outside follows the path shown in FIG. 1-1, for example. That is, as shown in FIG. 1A, the light is incident on the side surface 13a, which is the surface where the hole portion 17 of the low refractive index layer 13 is formed, and is refracted at an angle closer to the normal direction of the substrate 11. As a result, compared with the case where the low refractive index layer 13 is not provided, the light L1 reaching the anode layer 12 and the substrate 11 causes total reflection at the interface between the anode layer 12 and the substrate 11 and the outer surface of the substrate 11. It becomes difficult. Therefore, by providing the low refractive index layer 13, more light emitted from the organic semiconductor layer 15 can be extracted from the substrate 11 side, and the light extraction efficiency is improved.

In the present embodiment, the low refractive index layer 13 is insulative. Thereby, since the low refractive index layer 13 insulates the anode layer 12 and the cathode layer 16 from each other at a predetermined interval, the organic semiconductor layer 15 can emit light by applying a voltage. For this reason, the low refractive index layer 13 needs to be a high resistivity material, and the electrical resistivity is required to be 10 ⁸ Ωcm or more, preferably 10 ¹² Ωcm or more. Specific materials include metal nitrides such as silicon nitride, boron nitride, and aluminum nitride; metal oxides such as silicon oxide (silicon dioxide) and aluminum oxide, sodium fluoride, lithium fluoride, magnesium fluoride, and fluoride. Metal fluorides such as calcium and barium fluoride can be mentioned, but also polyimide, polyvinylidene fluoride, polymer compounds such as parylene, coating type silicone such as poly (phenylsilsesquioxane), spin-on-glass (SOG) can also be used.

Here, in order to manufacture the organic light emitting device 10 that is less likely to cause short circuit and current leakage with good reproducibility, the thickness of the low refractive index layer 13 is preferably as thick as possible. On the other hand, in order to suppress the thickness of the organic light emitting device 10 as a whole. In particular, the thickness of the low refractive index layer 13 preferably does not exceed 1 μm. Further, the narrower the gap between the anode layer 12 and the cathode layer 16, the lower the voltage required for light emission. From this point of view, the thinner the low refractive index layer 13 is more preferable. However, if it is too thin, the dielectric strength may not be sufficient with respect to the voltage for driving the organic light emitting element 10. Here, regarding the dielectric strength, when a rated driving voltage is applied in a state where the low refractive index layer 13 in which the hole 17 is not formed is directly sandwiched between the anode layer 12 and the cathode layer 16, the anode layer 12 and the cathode layer 16 are applied. the current density flowing between is preferably at 0.1 mA / cm ² or less, and more preferably 0.01 mA / cm ² or less. Further, since it is preferable to withstand a voltage 2V higher than the rated driving voltage of the organic light emitting element 10, for example, when the rated driving voltage is 5V, an anode and a cathode formed on both surfaces of the low refractive index layer 13 It is necessary to satisfy the above current density when a voltage of about 7 V is applied between the two. The upper limit of the thickness of the low refractive index layer 13 that satisfies this is preferably 750 nm or less, more preferably 400 nm or less, and even more preferably 200 nm or less. Further, the lower limit is preferably 15 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more.

(Translucent conductive layer)
The translucent conductive layer 14 is not necessarily formed in the conventional organic light emitting device structure. On the other hand, the translucent conductive layer 14 is essential in the organic light emitting device 10 of the present invention, and plays the following three roles.
(I) Functions as a substantially lower electrode for applying a voltage to the organic semiconductor layer 15 (ii) When the hole 17 is formed through the lower electrode layer, the center of the hole 17 (Iii) By forming the translucent conductive layer 14 in the hole 17 so that the surface thereof is concave, the film thickness of the organic semiconductor layer 15 formed thereon is made uniform. thing

The translucent conductive layer 14 is transparent and conductive with respect to light emitted from the light emitting layer 15 a of the organic semiconductor layer 15. Furthermore, it is preferable that the hole injection barrier to the organic semiconductor layer 15 is further lowered to increase the hole injection efficiency.

In the present embodiment, translucent conductive layer 14 is formed in electrical contact with anode layer 12. Here, the translucent conductive layer 14 has a higher conductivity than the organic semiconductor layer 15. When attention is paid to the function of applying a voltage to the organic semiconductor layer 15 as an element, the translucent conductive layer 14 is It functions as a substantial anode. The conductivity of the translucent conductive layer 14 is preferably 1 × 10 ⁻³ S / cm or more, and more preferably 1 S / cm or more.

The difference between the refractive index of the translucent conductive layer 14 and the refractive index of the organic semiconductor layer 15 is preferably 0.1 or less. Thereby, although the translucent conductive layer 14 functions electrically as a substantial anode, since the refractive index is optically almost the same as the organic semiconductor layer 15, the organic semiconductor layer is from the viewpoint of the refractive index. 15 functions as an integral layer. The integral layer and the low refractive index layer 13 form a high refractive index / low refractive index interface, which contributes to an improvement in light extraction efficiency. On the other hand, if the difference in refractive index between the translucent conductive layer 14 and the organic semiconductor layer 15 is greater than 0.1, a new refractive index interface is formed between the two layers. In this case, the light incident on the low refractive index layer 13 through this extra interface has a sufficient light extraction effect at the high refractive index / low refractive index interface between the integral layer and the low refractive index layer 13. I can't get it.
As a material used for the translucent conductive layer 14 to satisfy such a condition, for example, a conductive polymer material or the like can be used. More specifically, copper phthalocyanine, a mixture of polyethylene dioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT: PSS), fluorocarbon, and the like can be given. An inorganic translucent conductive material can also be used. Examples thereof include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide.

Furthermore, the translucent conductive layer 14 of the present embodiment is formed inside the hole 17. And especially when arrange | positioning along the bottom face of the hole part 17, the location where light emission occurs can be made relatively upper with respect to the case where the translucent conductive layer 14 is not provided. That is, when the translucent conductive layer 14 is not provided, the lower electrode surface is on the bottom surface of the hole 17. Therefore, light emission is likely to occur at a location near the bottom surface of the hole portion 17. In contrast, in the present embodiment, the substantially lower electrode surface is an interface between the translucent conductive layer 14 and the organic semiconductor layer 15. In this case, since the translucent conductive layer 14 is disposed on the bottom surface of the hole portion 17, no light is emitted in the vicinity of the bottom surface of the hole portion 17, and the organic semiconductor layer formed further above the translucent conductive layer 14. Light emission occurs in the 15 light emitting layers 15a. That is, by providing the translucent conductive layer 14, the light emission location in the hole 17 can be moved relatively upward. As a result, light incident at a low incident angle on the side surface 13a of the hole 17 of the low refractive index layer 13 increases. That is, when the light-transmitting conductive layer 14 is not disposed and light is emitted in the vicinity of the bottom surface of the hole portion 17, the light that travels at a near-horizontal angle parallel to the surface of the substrate 11 and is difficult to be extracted to the outside. Since the light does not effectively enter 13a, the degree of improvement in light extraction efficiency is small. On the other hand, when the translucent conductive layer 14 is provided as in the present embodiment, most of the light traveling at a horizontal angle parallel to the surface of the substrate 11 is incident on the side surface 13a of the hole 17 and the light travels. Since the direction changes closer to the normal line of the substrate 11, total reflection is less likely to occur at the interface between the anode layer 12 and the substrate 11 and the outer surface of the substrate 11, and the light extracted outside increases.

Moreover, it is preferable that the translucent conductive layer 14 of the present embodiment is formed not only along the entire bottom surface of the hole portion 17 but also along the side surface 13a. In other words, it is preferable that the upper surface (the surface on the organic semiconductor layer 15 side) of the translucent conductive layer 14 has a shape recessed toward the anode layer 12 at the position where the hole 17 is formed. When the translucent conductive layer 14 is also formed on the side surface 13a of the hole 17, current is also supplied to the organic semiconductor layer 15 located near the side surface 13a in the hole 17, and the light emission in this portion is emitted. Light emission also occurs in the layer 15a. That is, since light emission occurs in a wide region in the hole portion 17, the amount of light incident on the side surface 13a of the low refractive index layer 13 increases, and the light extraction efficiency is improved. Moreover, since it can suppress that an electric current flows locally, durability of the organic light emitting element 10 improves.
The shape of the upper surface of the translucent conductive layer 14 is more preferably a concave curved surface whose curvature changes gently. With this shape, the film thickness of the organic semiconductor layer 15 formed thereon becomes relatively uniform. Accordingly, the light emission is uniformly performed and the light emitting area is widened, so that the luminance is improved, and the current flows uniformly without being concentrated locally, so that the durability is also improved. As will be described in detail later, the translucent conductive layer 14 can be formed by a coating method. When the translucent conductive layer 14 is formed by a coating method, it is easier to make the upper surface of the translucent conductive layer 14 into a concave curved surface shape, so that the organic light emitting device 10 can be manufactured more easily.

In the present embodiment, the translucent conductive layer 14 may be formed extending on the low refractive index layer 13. Thus, when the translucent conductive layer 14 is formed not only inside the hole 17 but also both on the low refractive index layer 13, the entire organic semiconductor layer 15 is compared with the case where it is formed only inside the hole 17. Therefore, local heat generation is suppressed, and the durability of the organic light emitting element 10 is improved.

(Organic semiconductor layer)
The organic semiconductor layer 15 is composed of one layer including the light emitting layer 15 a or a layer made of a plurality of stacked organic compounds, and is formed on the translucent conductive layer 14. At this time, the organic semiconductor layer 15 is formed so that at least a part thereof enters the hole 17. By doing in this way, among the light emitted from the light emitting layer 15 a included in the organic semiconductor layer 15, the light that travels in a horizontal direction parallel to the surface of the substrate 11 and is difficult to be extracted to the outside is transmitted to the side surface of the hole 17. More incident light can enter the low refractive index layer 13 from 13a.
In addition to this, it is more preferable that the light emitting layer 15 a of the organic semiconductor layer 15 is formed so that at least a part thereof enters the hole portion 17. By doing in this way, the area | region which light-emits exists in the hole part 17 more reliably, and light extraction efficiency improves further. FIG. 1-1 shows a case where at least a part of the light emitting layer 15a enters the inside of the hole portion 17, but FIG. 1-2 shows an example where the light emitting layer 15a does not enter the inside of the hole portion 17. It was. That is, in the present embodiment, the hole portion 17 is a portion below the dotted line shown in FIGS. 1-1 and 1-2. In FIG. 1-1, a part of the light emitting layer 15a enters a part below the dotted line. In contrast, in FIG. 1-2, a part of the organic semiconductor layer 15 enters a portion below the dotted line, but the light emitting layer 15a is formed at a portion above the dotted line.

The organic semiconductor layer 15 is preferably formed with a uniform thickness at the position where the hole 17 is formed. As a result, light emission can be generated more uniformly in the light emitting layer 15a at the positions of the holes 17. In other words, if the film thickness of the organic semiconductor layer 15 is not uniform at the position where the hole 17 is formed, current tends to flow in the thinner part than in the thicker part, and light emission is more likely to occur in this part. , Non-uniform light emission. In this case, the current is locally concentrated and heat is generated, so that the organic semiconductor layer 15 is likely to be deteriorated, and the durability of the organic light emitting element 10 is lowered. On the other hand, when the film thickness of the organic semiconductor layer 15 is uniform at the position where the hole 17 is formed, the current flows uniformly, so that the light emission is uniform. In this case, since the current does not flow locally, the durability of the organic light emitting element 10 can be improved. Further, since the light emitting region is widely distributed in or above the hole portion 17, the amount of light incident on the side surface 13a of the low refractive index layer 13 increases, and the light extraction efficiency is improved.

For this reason, the variation in the thickness of the organic semiconductor layer 15 is preferably (minimum value of film thickness) / (maximum value of film thickness) ≧ 0.7. In the present embodiment, the uniform thickness of the organic semiconductor layer 15 means that the variation in film thickness is within this range.

In the present embodiment, the thickness of the organic semiconductor layer 15 can be measured by taking an SEM photograph of a vertical cross-sectional sample of the organic light emitting element 10. Here, the cross section for measurement is a cross section that divides the hole portion 17 into two substantially in plan view. In addition, when the planar shape of the hole part 17 is a rectangle, it is set as the cross section which does not cross a corner | angular part and crosses a side as perpendicularly as possible.
FIG. 1-3 shows an example of measuring the film thickness of the organic semiconductor layer 15. The sample was produced as follows. First, an anode layer 12 (ITO) and a low refractive index layer 13 (SiO ₂ ) are laminated on a glass substrate, and a hole 17 penetrating these two layers is formed. On this concavo-convex structure, a mixture of polyethylene dioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT: PSS) is first formed as a transparent conductive layer by spin coating, and then the organic semiconductor layer 15 is formed thereon. As a film, Alq _{3 is formed} by vacuum deposition. In the cross-sectional photograph of FIG. 1-3, the maximum value of the film thickness in the hole 17 region of the organic semiconductor layer 15 is about 80 nm, the minimum value is about 60 nm, and the ratio of the minimum value / maximum value is 0.75.

The light emitting layer 15 a included in the organic semiconductor layer 15 includes a light emitting material that emits light when a voltage is applied between the anode layer 12 and the cathode layer 16. As the light emitting material, both low molecular compounds and high molecular compounds can be used. In this embodiment mode, it is preferable to use a phosphorescent organic compound and a metal complex as the light-emitting material. Some metal complexes exhibit phosphorescence, and such metal complexes are also preferably used. In the present embodiment, it is particularly desirable to use a cyclometalated complex from the viewpoint of improving luminous 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 of the complex include Ir, Pd and Pt having a ligand, and an iridium (Ir) complex is 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, which 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 MEH-PPV; π-conjugated polymer compounds such as polyfluorene derivatives and polythiophene derivatives; low molecular dyes and tetraphenyldiamine; And a polymer in which triphenylamine is introduced into the main chain or side chain. A light emitting high molecular compound and a light emitting low molecular weight compound can also be used in combination.
The light emitting layer 15a 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.

Here, the organic semiconductor layer 15 may include a hole transport layer for receiving holes from the translucent conductive layer 14 and transporting them to the light emitting layer 15a. The hole transport layer is disposed between the translucent conductive layer 14 and the light emitting layer 15a.
As a hole transport material for forming such a hole transport layer, a known material can be used, for example, TPD (N, N′-dimethyl-N, N ′-(3-methylphenyl)- Α-NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl); m-MTDATA (4,4 ′, 1,1′-biphenyl-4,4′diamine); Low molecular weight triphenylamine derivatives such as 4 ″ -tris (3-methylphenylphenylamino) triphenylamine); polyvinylcarbazole; polymer compounds obtained by introducing a polymerizable substituent into the above triphenylamine derivative, and the like. Can be mentioned. The above hole transport materials may be used singly or in combination of two or more, or different hole transport materials may be laminated and used. The thickness of the hole transport layer depends on the conductivity of the hole transport layer and cannot be generally limited, but is preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and particularly preferably 10 nm to 500 nm. Is desirable.

The organic semiconductor layer 15 may include an electron transport layer for receiving electrons from the cathode layer 16 and transporting them to the light emitting layer 15a. The electron transport layer is disposed between the cathode layer 16 and the light emitting layer 15a.
Examples of materials that can be used for such an electron transport layer include quinoline derivatives, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, and the like. More specifically, tris (8-quinolinolato) aluminum (abbreviation: Alq), tris (4-methyl-8-quinolinolato) aluminum, bis (10-hydroxybenzo [h] quinolinato) beryllium, bis (2-methyl-) 8-quinolinolato) (4-phenylphenolato) aluminum, bis [2- (2-hydroxyphenyl) benzoxazolate] zinc, bis [2- (2-hydroxyphenyl) benzothiazolate] zinc, 2- (4-biphenylyl) ) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole and 1,3-bis [5- (p-tert-butylphenyl) -1,3,4-oxadiazole -2-yl] benzene, 3- (4-biphenylyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4 Triazole (abbreviation: TAZ), bathophenanthroline, bathocuproin (abbreviation: BCP), triphenylbisimidazole (BPBI), 2,2 ', 2 "-(1,3,5-Benzenetriyl) tris [1-phenyl-1H- benzimidazole] (abbreviation: TPBI), 3,3 '-[5'-[4- (3-Pyridinyl) phenyl] [1,1 ': 3', 1 "-terphenyl] -4,4" -diyl] bispyridine (Abbreviation: TPyTPB), 4,4 '-[5'-[3- (4-Pyridinyl) phenyl] [1,1 ': 3', 1 "-terphenyl] -3,3" -diyl] bispyridine (abbreviation) : M4TPyTPB), 3,3 '-[5'-[3- (3-Pyridinyl) phenyl] [1,1 ': 3', 1 "-terphenyl] -3,3" -diyl] bispyridine (abbreviation: mTPyTPB) ), 2,2 '-[5'-[3- (2-Pyridinyl) phenyl] [1,1 ': 3', 1 "-terphenyl] -3,3" -diyl] bispyridine (abbreviated) Name: m2TPyTPB), 3- [4- [Bis (2,4,6-trimethylphenyl) boryl] -3,5-dimethylphenyl] pyridin (abbreviation: Py211B), etc. Among them, TPBI, TPyTPB, m4TPyTPB, mTPyTPB , M2TPyTPB and Py211B can be used more preferably.

Further, in the organic semiconductor layer 15, a hole blocking layer may be provided between the electron transport layer and the light emitting layer 15a. By providing this hole blocking layer, it is possible to prevent holes from passing through the light emitting layer 15a and to efficiently recombine holes and electrons in the light emitting layer 15a.
In order to form the hole blocking layer, a known material such as a triazole derivative, an oxadiazole derivative, or a phenanthroline derivative is used.

(Cathode layer)
The cathode layer 16 injects electrons into the organic semiconductor layer 15 by applying a voltage between the cathode layer 16 and the anode layer 12. The cathode layer 16 is continuously formed along with the organic semiconductor layer 15 over the entire light emitting surface.
The material used for the cathode layer 16 is not particularly limited as long as it has electrical conductivity in the same manner as the anode layer 12. However, a material having a low work function and being chemically stable is preferable. . The work function is preferably 2.9 eV or less in consideration of chemical stability. Specifically, materials such as Al, MgAg alloy, Al and alkali metal alloys such as AlLi and AlCa can be exemplified. The thickness of the cathode layer 16 is preferably 10 nm to 1 μm, more preferably 50 nm to 500 nm. In the case of the organic light emitting device 10 according to the present embodiment, light emitted from the organic semiconductor layer 15 is extracted from the substrate 11 side. Therefore, the cathode layer 16 may be made of an opaque material. Furthermore, when light is extracted only from the substrate 11 side, the material of the cathode layer 16 is preferably a material that is reflective to the light emitted from the light emitting layer 15a. When a light-reflective material is used for the cathode layer 16, light emitted from the light-emitting layer 15a toward the cathode layer 16 is reflected from the surface of the cathode layer 16 and extracted from the substrate side, so that the light extraction efficiency is improved. . In this case, the higher the reflectance of the material used for the cathode layer 16, the more the light extraction efficiency is improved. From this viewpoint, it is preferable to use Al, Ag, Pt, Rh, and alloys thereof as the material of the cathode layer 16.

Further, a cathode buffer layer (not shown) may be provided adjacent to the cathode layer 16 for the purpose of lowering the electron injection barrier from the cathode layer 16 to the organic semiconductor layer 15 and increasing the electron injection efficiency.
For the cathode buffer layer, a metal material having a work function lower than that of the cathode layer 16 is preferably used. For example, alkali metals (Na, K, Rb, Cs), alkaline earth metals (Sr, Ba, Ca, Mg), rare earth metals (Pr, Sm, Eu, Yb), or fluorides or chlorides of these metals, A simple substance selected from oxides or a mixture of two or more can be used. The thickness of the cathode buffer layer is preferably from 0.05 nm to 50 nm, more preferably from 0.1 nm to 20 nm, and even more preferably from 0.5 nm to 10 nm.

(Hole)
The hole 17 is for extracting light emitted from the organic semiconductor layer 15, and is formed so as to penetrate the low refractive index layer 13 in the present embodiment. Thus, the light emitted from the organic semiconductor layer 15 by providing the hole portion 17 mainly propagates through the inside of the hole portion 17 and the low refractive index layer 13 and is extracted from the substrate 11 side and the cathode layer 16 side. Can do.

The shape of the hole portion 17 is not particularly limited, but is preferably a polygonal column shape such as a cylindrical shape or a quadrangular column, or a stripe shape from the viewpoint of easy shape control. In these shapes, the in-plane shape of the low refractive index layer 13 may change in the thickness direction of the low refractive index layer 13, or the size of the shape may change. That is, for example, a cone shape, a pyramid shape, a truncated cone shape, a truncated pyramid shape, and the like may be used. By appropriately selecting the shape of the hole 17, it is possible to control the light distribution when the light emitted from the organic semiconductor layer 15 is extracted to the outside.

When the size of the hole portion 17 is large, the light emitted in the hole portion 17 travels directly or while being reflected on the surface of the cathode layer 16 or the surface of the low refractive index layer 13 and enters the side surface 13a of the low refractive index layer 13. By the time, it is absorbed and attenuated by the organic semiconductor layer 15 or the translucent conductive layer 14. In order to reduce the absorption loss due to the organic semiconductor layer 15 or the translucent conductive layer 14, the size of the hole portion 17 is 3 μm in maximum when viewed from the normal direction of the substrate 11, that is, in plan view. The following is preferable. Here, the maximum width is the maximum value of the distance between two parallel straight lines that touch the plane figure of the hole 17 and sandwich it. Moreover, as for the magnitude | size of the hole part 17, it is more preferable that the maximum width is 1 micrometer or less by planar view.

1-1, the side surface 13a of the low refractive index layer 13 is formed perpendicular to the surface of the substrate 11, and in this case, the inclination angle of the side surface 13a of the hole 17 (with respect to the plane of the substrate 11). Angle) is 90 °. However, the inclination angle is not limited to this, and can be changed as appropriate depending on the material used for the low refractive index layer 13 to increase the efficiency of extracting light emitted from the organic semiconductor layer 15 to the outside. In the present embodiment, the inclination angle is preferably 45 ° or more, and more preferably 60 ° or more. Moreover, in this Embodiment, although the side surface 13a was planar shape, it is not restricted to this, A curved surface shape may be sufficient.

Further, the arrangement of the holes 17 viewed from the upper side on which the respective layers constituting the organic light emitting element 10 are laminated is not particularly limited, and may be regular or irregular. As an example of a typical arrangement, a square (square) arrangement in which the holes 17 are arranged in a repeating unit as a square as shown in FIG. 1-4 (a), or as shown in FIG. 1-4 (b). A triangular arrangement (hexagonal arrangement, staggered arrangement) in which each hole portion 17 is arranged as a regular triangle or a regular hexagon is exemplified.

In the organic light emitting device 10 described in detail above, the translucent conductive layer 14 is formed to extend on the low refractive index layer 13, but is not limited thereto.
FIG. 2 is a partial cross-sectional view illustrating a second example of an organic light emitting device to which the present embodiment is applied.
In the organic light emitting device 10 shown in FIG. 2, the light transmitting conductive layer 14 is also formed on the low refractive index layer 13 in the organic light emitting device 10 shown in FIG. The layer 14 is not formed on the low refractive index layer 13 but is selectively formed inside the hole 17.
In this case, the transport of holes by the translucent conductive layer 14 is difficult to reach the portion of the organic semiconductor layer 15 formed on the low refractive index layer 13. Therefore, the light emitting region of the organic semiconductor layer 15 by the light emitting layer 15a is almost limited to the position of the hole 17, and the whole or most of the light emitting region is present in the hole 17, so that the light extraction efficiency tends to be high.

Furthermore, the organic semiconductor layer 15 need not extend over the low refractive index layer 13.
FIG. 3 is a partial cross-sectional view illustrating a third example of the organic light emitting device to which the present embodiment is applied.
In the organic light emitting device 10 shown in FIG. 3, the organic semiconductor layer 15 is also formed on the low refractive index layer 13 in the organic light emitting device 10 shown in FIG. It is not formed on the layer 13 but is selectively formed inside the hole 17. As a result, the light-emitting region of the organic semiconductor layer 15 by the light-emitting layer 15a is further limited to the inside of the hole 17 than the organic light-emitting element 10 shown in FIG. In particular, since the organic semiconductor layer 15 is also present in a region adjacent to the side surface 13a of the hole 17, more light enters the low refractive index layer 13 through the side surface 13a, and light extraction efficiency is improved.

Moreover, in the example mentioned above, although the surface by the side of the organic-semiconductor layer 15 of the translucent conductive layer 14 of the organic-semiconductor layer 15 makes the curved surface shape dented in the anode layer 12 side in the position where the hole part 17 is formed, it mentioned. The other cases will be described below.
4 to 7 are partial cross-sectional views illustrating fourth to seventh examples of the organic light emitting device to which the present embodiment is applied.
The organic light emitting device 10 shown in FIG. 4 is different from the organic light emitting device 10 shown in FIG. 1-1 in that the surface of the translucent conductive layer 14 on the organic semiconductor layer 15 side is at a position where the hole 17 is formed. The only difference is that it is recessed in a rectangular shape on the anode layer 12 side. The organic light emitting device 10 shown in FIG. 5 is different from the organic light emitting device 10 shown in FIG. 2 in that the surface of the translucent conductive layer 14 on the organic semiconductor layer 15 side is an anode at a position where the hole 17 is formed. The only difference is that the layer 12 is recessed in a rectangular shape.

6 differs from the organic light-emitting device 10 shown in FIG. 5 only in that the light-transmitting conductive layer 14 is formed only on the bottom surface of the hole 17. In this case, the place where the translucent conductive layer 14 and the side surface 13 a of the low refractive index layer 13 are in contact is limited to the periphery of the bottom surface of the hole portion 17.
Further, the organic light emitting device 10 shown in FIG. 7 is different from the organic light emitting device 10 shown in FIG. 3 in that the surface of the translucent conductive layer 14 on the organic semiconductor layer 15 side is recessed at the position where the hole 17 is formed. The only difference is that it is flat.

In the case of the organic light emitting device 10 shown in FIGS. 4 to 7, the translucent conductive layer 14 is preferably formed with a uniform thickness along the inner surface of the hole 17. In this case, the light emitting region is positioned in the vicinity of the side surface 13a of the low refractive index layer 13 as compared with the case where the surface of the translucent conductive layer 14 on the organic semiconductor layer 15 side is recessed in a curved shape. Therefore, more light is incident on the side surface 13a, and the light extraction efficiency is further improved. Here, the uniform thickness of the light-transmitting conductive layer 14 means that the film thickness of the light-transmitting conductive layer 14 is (minimum value of film thickness) / (maximum value of film thickness) ≧ 0.7. Means that.

Moreover, in the example mentioned above, although the hole part 17 penetrated only the low-refractive-index layer 13, it is not restricted to this.
FIG. 8 is a partial cross-sectional view illustrating an eighth example of an organic light emitting device to which the present embodiment is applied.
The organic light emitting device 10 shown in FIG. 8 has a hole 17 not only penetrating through the low refractive index layer 13 but also the anode layer 12 through the organic light emitting device 10 shown in FIG. Yes. In this case, since the anode layer 12 is removed at the position of the hole portion 17, the absorption loss by the anode layer 12 with respect to the light extracted from the bottom portion of the hole portion 17 is reduced. Therefore, the light extraction efficiency is improved.
The hole 17 does not have to be formed through the anode layer 12 and may be formed halfway. That is, it may be formed by piercing a part of the anode layer 12.

FIG. 9 is a partial cross-sectional view illustrating a ninth example of an organic light emitting device to which the present embodiment is applied.
In the organic light emitting device 10 illustrated in FIG. 9, the substrate 11 has a perforated portion 18 that is recessed at a position where the hole 17 is formed. In FIG. 9, the boundary portion between the hole portion 17 and the perforated portion 18 is illustrated by the lower dotted line in the drawing. In the case of the organic light emitting device 10 shown in FIG. 8, the light reflected from the upper surface of the substrate 11, which is the bottom surface of the hole portion 17, also enters the substrate 11 on the side surface 18 a of the hole portion 18. Can invade. Therefore, the light extraction efficiency is further improved.
In the case of the organic light emitting device 10 shown in FIGS. 8 and 9, the surface of the translucent conductive layer 14 on the organic semiconductor layer 15 side has a rectangular shape on the anode layer 12 side at the position where the hole 17 is formed. Although recessed, this interface may be recessed in a curved surface shape.

10 to 11 are partial cross-sectional views illustrating tenth to eleventh examples of the organic light emitting device to which the present embodiment is applied.
In the organic light emitting device 10 shown in FIG. 10, the translucent conductive layer 14 protrudes above the upper surface of the low refractive index layer 13 in the outer peripheral portion of the hole portion 17 as compared with the organic light emitting device 10 shown in FIG. 2. Is formed. Further, the organic semiconductor layer 15 and the cathode layer 16 formed on the translucent conductive layer 14 also have a shape that rises in the vicinity of the outer peripheral portion of the hole portion 17 corresponding to the shape of the translucent conductive layer 14. Yes. The organic light-emitting element 10 shown in FIG. 11 has a light-transmitting conductive layer 14, an organic semiconductor layer 15, and a cathode layer 16 that are different from the organic light-emitting element 10 shown in FIG. In the same manner as in the case of the element 10, the hole 17 has a shape that protrudes at or near the outer periphery.
The reason why the translucent conductive layer 14 takes such a form is likely to occur when the translucent conductive layer 14 is formed using a mask in the manufacture of the organic light emitting element 10. As will be described in detail later, the translucent conductive layer 14 is formed by forming a hole 17 in the low refractive index layer 13 and then filling the hole 17 with a material for forming the translucent conductive layer 14. . Here, in order to selectively form the transparent conductive layer 14 at the position of the hole 17, for example, the mask used when forming the hole 17 in the low refractive index layer 13 is left as it is. May be used to form the translucent conductive layer 14 in the hole 17. At this time, after forming the translucent conductive layer 14 on the mask and then removing the mask, the translucent conductive layer 14 remains on the outer peripheral portion of the hole 17 in a raised form. Subsequently, the organic semiconductor layer 15 and the cathode layer 16 are formed thereon, whereby the organic light emitting device 10 shown in FIGS. 10 to 11 is manufactured.

In the case of the organic light emitting device 10 shown in FIGS. 10 and 11, the hole 17 is formed only in the low refractive index layer 13, but the hole 17 may be formed through the anode layer 12. . Further, the hole portion 17 may be formed by further drilling the substrate 11.

[Organic light emitting device in which upper electrode is translucent cathode layer]
In all of the application examples of the embodiment of the organic light emitting device 10 of the present invention described with reference to FIGS. 1-1 to 11, a light-transmitting anode layer 12 is provided in contact with the substrate 11, and light is extracted from the substrate 11 side. It is. On the other hand, another embodiment having a different electrode configuration will be described below by showing a specific application example.

FIG. 12 is a partial cross-sectional view illustrating a twelfth example of an organic light emitting device to which the present embodiment is applied. This is an application example of one embodiment having a different electrode configuration, and the electrode layer on the side opposite to the substrate 11 is a translucent cathode layer 16 and has a structure for extracting light from the side opposite to the substrate 11. The application examples of the embodiments having different electrode configurations shown as the twelfth example exist corresponding to all the structures shown in FIGS. 1-1 to 11. Here, FIG. 12 corresponding to FIG. 1-1 will be representatively described, but the present embodiment can be similarly applied to other structures shown in FIGS. 1-2 to 11. 8 and 9, even when the opaque anode layer 12 is used, since the hole 17 penetrates the opaque anode layer 12 on the substrate 11 side, light is emitted also from the substrate 11 side. To do.

As a material of the light-transmitting cathode layer 16, a conductive transparent metal oxide can be used. Specific examples of the conductive transparent oxide include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide.
Further, it is preferable to form a cathode buffer layer (not shown) between the light-transmitting cathode layer 16 and the organic semiconductor layer 15 to improve the efficiency of electron injection into the organic semiconductor layer 15. Examples of materials applicable to the cathode buffer layer include alkali metals (Na, K, Rb, Cs), alkaline earth metals (Sr, Ba, Ca, Mg), and rare earth metals (Pr, Sm, Eu, Yb). Or a single substance or a mixture of two or more selected from fluorides, chlorides and oxides of these metals. The thickness of the cathode buffer layer is preferably 10 nm or less in order to suppress transmission loss.

When it is not necessary to extract light from the substrate 11 side of the organic light emitting element 10 as in the twelfth example, the material of the substrate 11 is not limited to one that is transparent to visible light, but is opaque. Things can also be used. Specifically, silicon (Si), copper (Cu), silver (Ag), gold (Au), platinum (Pt), tungsten (W), titanium (Ti), tantalum (Ta), or niobium (Nb) A simple substance of these, alloys thereof, stainless steel, or the like can also be used.

The material used for the anode layer 12 needs to have electrical conductivity. Specifically, it has a high work function, and the work function is preferably 4.5 eV or more. In addition, it is preferable that the electrical resistance does not change significantly with respect to the alkaline aqueous solution. A light-transmitting metal oxide can be used as a material that satisfies such conditions. Specific examples of the compound include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide.

Furthermore, when light is extracted only from the side opposite to the substrate 11, the material of the anode layer 12 on the substrate 11 side is preferably a material that is reflective to the light emitted from the light emitting layer 15a. When a light-reflective material is used for the anode layer 12, light emitted from the light-emitting layer 15a toward the anode layer 12 is reflected by the surface of the anode layer 12 and extracted from the side opposite to the substrate 11, so that the light extraction efficiency Will improve. In this case, the light extraction efficiency improves as the reflectance of the material used for the anode layer 12 increases. Examples of materials applicable to the reflective anode layer 12 include high reflectivity metals such as Al, Ag, Mo, W, Ni, and Cr, high reflectivity amorphous alloys such as NiP, NiB, CrP, and CrB, and NiAl. Examples thereof include a microcrystalline alloy having a high reflectance such as.

Further, it is preferable to form an anode buffer layer (not shown) between the reflective anode layer 12 and the organic semiconductor layer 15 to improve the efficiency of hole injection into the organic semiconductor layer 15. Examples of materials applicable to the anode buffer layer include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide.
The description of the other components in the organic light emitting element 10 of the twelfth example is the same as the description of the first example described with reference to FIG.

[Organic light emitting device in which upper electrode is translucent anode layer]
FIG. 13 is a partial cross-sectional view illustrating a thirteenth example of an organic light emitting device to which the present embodiment is applied. The application examples of the embodiments having different electrode configurations shown as the thirteenth example exist corresponding to all the structures shown in FIGS. Here, the description will be made with reference to FIG. 13 corresponding to FIG. 1-1. However, the present embodiment can be similarly applied to other structures shown in FIGS. 1-2 to 11. In the structure corresponding to FIGS. 8 and 9, even when the opaque cathode layer 16 is used, the hole 17 penetrates the opaque cathode layer 16 on the substrate 11 side, so that light is also emitted from the substrate 11 side. .

The structure of the organic light emitting device 10 shown in FIG. 13 is a structure in which the positions of the light-transmitting anode layer 12 and the cathode layer 16 are interchanged in the organic light emitting device 10 of FIG. 1-1.
As a material for the light-transmitting anode layer 12, a conductive transparent metal oxide can be used. Specific examples of the conductive transparent oxide include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide.

The translucent conductive layer 14 in the thirteenth example has transparency and conductivity with respect to light emitted from the light emitting layer 15a of the organic semiconductor layer 15. Further, it is preferable to have a function of lowering the electron injection barrier to the organic semiconductor layer 15 and increasing the electron injection efficiency. As a material used for the translucent conductive layer 14 in order to satisfy such a condition, for example, an n-type doped conductive polymer can be used. Specific examples of the n-type doped conductive polymer include polyparaphenylene and polyparaphenylene vinylene. Further, since the n-type doped conductive polymer can be formed by coating, a curved surface in which the interface between the organic semiconductor layer 15 and the translucent conductive layer 14 is recessed toward the substrate 11 at the position where the hole 17 is formed. It is easy to form. The description of other matters regarding the embodiment of the light-transmitting conductive layer of the thirteenth example is the same as the description of the first example.

When it is not necessary to extract light from the substrate 11 side of the organic light emitting element 10 as in the thirteenth example, the material of the substrate 11 is not limited to a material that is transparent to visible light, but is opaque. You can also use anything. Specifically, silicon (Si), copper (Cu), silver (Ag), gold (Au), platinum (Pt), tungsten (W), titanium (Ti), tantalum (Ta), or niobium (Nb) A simple substance of these, alloys thereof, stainless steel, or the like can also be used.

The material used for the cathode layer 16 is not particularly limited as long as it has electrical conductivity in the same manner as the anode layer 12. However, a material having a low work function and being chemically stable is preferable. . The work function is preferably 2.9 eV or less in consideration of chemical stability. Specifically, materials such as Al, MgAg alloy, Al and alkali metal alloys such as AlLi and AlCa can be exemplified. The thickness of the cathode layer 16 is preferably 10 nm to 1 μm, more preferably 50 nm to 500 nm.

Furthermore, when light is extracted only from the side opposite to the substrate 11, the material of the cathode layer 16 is preferably a material that is reflective to the light emitted from the light emitting layer 15a. When a light-reflective material is used for the cathode layer 16, light emitted from the light emitting layer 15a toward the cathode layer 16 is reflected by the surface of the cathode layer 16 and is extracted from the substrate 11, so that the light extraction efficiency is improved. To do. In this case, the higher the reflectance of the material used for the cathode layer 16, the more the light extraction efficiency is improved. From this viewpoint, it is preferable to use Al, Ag, Pt, Rh, and alloys thereof as the material of the cathode layer 16.

Further, it is preferable to form a cathode buffer layer (not shown) between the light-transmitting cathode layer 16 and the organic semiconductor layer 15 to improve the efficiency of electron injection into the organic semiconductor layer 15. Examples of materials applicable to the cathode buffer layer include alkali metals (Na, K, Rb, Cs), alkaline earth metals (Sr, Ba, Ca, Mg), and rare earth metals (Pr, Sm, Eu, Yb). Or a single substance or a mixture of two or more selected from fluorides, chlorides and oxides of these metals. The thickness of the cathode buffer layer is preferably 10 nm or less in order to suppress transmission loss.
The description of the other components in the organic light emitting element 10 of the thirteenth example is the same as the description of the first example described with reference to FIG.

[Organic light emitting device in which lower electrode is translucent cathode layer]
FIG. 14 is a partial cross-sectional view illustrating a fourteenth example of an organic light emitting device to which the present embodiment is applied. This is an application example of still another embodiment having a different electrode configuration, and the electrode layer on the side in contact with the substrate 11 is a translucent cathode layer 16 and has a structure for extracting light from the substrate 11 side. The application examples of the embodiments having different electrode configurations shown as the fourteenth example exist corresponding to all the structures shown in FIGS. Here, description will be made representatively with reference to FIG. 14 corresponding to FIG. 1-1, but the present embodiment can be similarly applied to other structures shown in FIG. 1-2 to FIG.

The translucent conductive layer 14 in the fourteenth example has transparency and conductivity with respect to light emitted from the light emitting layer 15a of the organic semiconductor layer 15. Further, it is preferable to have a function of lowering the electron injection barrier to the organic semiconductor layer 15 and increasing the electron injection efficiency. As a material used for the translucent conductive layer 14 in order to satisfy such a condition, for example, an n-type doped conductive polymer can be used. Specific examples of the n-type doped conductive polymer include polyparaphenylene and polyparaphenylene vinylene. Further, since the n-type doped conductive polymer can be formed by coating, a curved surface in which the interface between the organic semiconductor layer 15 and the translucent conductive layer 14 is recessed toward the substrate 11 at the position where the hole 17 is formed. It is easy to form. The description of other matters regarding the embodiment of the light-transmitting conductive layer of the fourteenth example is the same as the description of the first example.

The thickness of the substrate 11 is preferably 0.1 mm to 10 mm, more preferably 0.25 mm to 2 mm, although it depends on the required mechanical strength.
Further, when light is extracted only from the substrate 11 side, the material of the anode layer 12 on the side opposite to the substrate 11 is preferably a material that is reflective to the light emitted from the light emitting layer 15a. When a light-reflective material is used for the anode layer 12, light emitted from the light emitting layer 15a toward the anode layer 12 is reflected by the surface of the anode layer 12 and is extracted from the substrate 11, so that the light extraction efficiency is improved. To do. In this case, the light extraction efficiency improves as the reflectance of the material used for the anode layer 12 increases. Materials applicable to the reflective anode layer include high reflectivity metals such as Al, Ag, Mo, W, Ni, Cr, high reflectivity amorphous alloys such as NiP, NiB, CrP, CrB, NiAl, etc. And a highly crystalline microcrystalline alloy.

Further, it is preferable to form an anode buffer layer (not shown) between the reflective anode layer 12 and the organic semiconductor layer 15 to improve the efficiency of hole injection into the organic semiconductor layer 15. Examples of materials applicable to the anode buffer layer include ITO (indium tin oxide), IZO (indium-zinc oxide), indium oxide, tin oxide, and zinc oxide.
The description of the other components in the organic light emitting element 10 of the fourteenth example is the same as the description of the first example described with reference to FIG.

In the description of the application example of the embodiment of the organic light emitting device 10 of the present invention, any one of the lower electrode adjacent to the substrate 11 and the upper electrode far from the substrate 11 is from the light emitting layer. The element structure having translucency with respect to the emitted light has been mainly described. However, an element structure in which both electrodes have translucency and light is extracted from both the upper and lower surfaces of the organic light emitting element 10 may be used.

(Explanation of light extraction effect)
Next, the light extraction effect of the low refractive index layer in the organic light emitting device of this embodiment will be described with reference to FIGS. 15-1 and 15-2.
FIG. 15A shows the structure of the organic light emitting device 100 of the same prior art as in FIG. 19, in which a transparent first electrode 112, an organic layer 115 including a light emitting layer, a reflective property are sequentially formed on a transparent substrate 111. A structure in which the second electrode 116 is stacked is shown. Here, the state of light propagation varies depending on the radiation angle from the light emission position P (the angle with respect to the normal to the substrate plane). While the radiation angle is small, the light is extracted outside as indicated by the light beam L1. However, when the radiation angle increases, total reflection first occurs on the outer surface of the transparent substrate 111 (light ray L2). When the radiation angle further increases, total reflection occurs at the interface between the translucent first electrode 112 / transparent substrate 111 (light ray L3). These totally reflected lights are also reflected on the surface of the reflective second electrode 116 to become a waveguide mode and are not extracted outside.

On the other hand, FIG. 15-2 employs a structure in which a part of the organic layer 115 of the organic light emitting device 100 of FIG. 15-1 is replaced with a low refractive index layer 113 having a refractive index lower than that of the organic layer 115. FIG. 15-2 shows a case where the interface between the organic layer 115 and the low refractive index layer 113 is perpendicular to the plane of the transparent substrate 111. Here, the path of the light beam L1 is changed by providing the low refractive index layer 113 at a position where the light beam L1 does not enter the low refractive index layer 113 and the light beams L2 and L3 enter the low refractive index layer 113. Without causing the light beam L2 and the light beam L3 to be extracted to the outside. That is, when the light rays L2 and L3 are incident on the side surface 13a of the low refractive index layer 113, they are refracted toward the normal direction of the plane of the transparent substrate 111. In addition, when the light beam L2 and the light beam L3 are refracted at the interface of the low refractive index layer 113 / translucent first electrode 112, they are also refracted at the interface of the organic layer 115 / translucent first electrode 112. Compared to the normal direction of the plane of the transparent substrate 111, the light is refracted. In this way, the path along which the light beam L2 and the light beam L3 travel after the first transparent electrode 112 changes largely toward the normal direction of the plane of the transparent substrate 111 as compared with the case where the low refractive index layer 113 is not provided. The extent to which the path of the light beam L2 and the light beam L3 changes toward the normal direction of the plane of the transparent substrate 111 depends on the refractive index of the low refractive index layer 113, and specifically for the given light beam L2 and light beam L3. By appropriately selecting the refractive index of the low-refractive index layer 113, the incident angle to the interface between the transparent first electrode 112 / transparent substrate 111 and the outer surface of the transparent substrate 111 can be made smaller than the critical angle. Can be taken out.

And the organic light emitting element 10 of this Embodiment has the low-refractive-index layer 13 and the organic-semiconductor layer 15 which have the some through-hole 17 between the anode layer 12 and the cathode layer 16. FIG. When a voltage is applied, since the low refractive index layer 13 is insulative, current flows only through the organic semiconductor layer 15 disposed in the hole portion 17 (however, a conductive buffer layer such as PEDOT is disposed outside the hole portion). In this case, the current flows also in the region outside the hole portion 17).

Here, in the organic light emitting device 10 of the present embodiment, since the film thickness of the organic semiconductor layer 15 is uniform in the hole portion 17, uniform light emission is obtained in the hole portion 17, and the low refractive index layer is obtained. The light incident on the side surface 13a of the 13 is increased. Since the traveling direction of the light incident on the low refractive index layer 13 changes toward the normal direction of the plane of the substrate 11, the light is extracted outside and the extraction efficiency is improved. In addition, since current does not flow locally, durability is improved.
In the organic light emitting device 10 of the present embodiment, the translucent conductive layer 14 is formed only on the entire bottom surface of the hole portion 17 of the low refractive index layer 13 or along the entire bottom surface and the side surface 13a. With this configuration, when the organic light emitting element 10 is viewed in cross section, the probability that the light emission position is located in the hole portion 17 is increased. Therefore, more light is emitted from the light emitting position and incident on the side surface 13a of the low refractive index layer 13. Since the traveling direction of the light incident on the low refractive index layer 13 changes toward the normal direction of the plane of the substrate 11, the light is extracted outside and the extraction efficiency is improved.

Further, in the organic light emitting device 10 of the present embodiment, the maximum width in a plan view of the hole portion 17 formed in the low refractive index layer 13 is 3 μm or less. Thereby, the absorption loss by the translucent conductive layer 14 through which the light emitted from the light emitting position passes before entering the side surface 13a of the low refractive index layer 13 can be suppressed to a low level. For example, since the extinction coefficient of the material forming the translucent conductive layer 14 is generally about 0.01 to 0.1, the wavelength is assumed to be 555 nm (maximum visibility), and the light emission position is the center of the hole 17. Consider the case. In this case, when the light travels 1.5 μm in the in-plane direction of the substrate 11, the light enters the low refractive index layer 13. The light intensity at this time is 71% of the original light intensity when the extinction coefficient is 0.01. Yes, when the extinction coefficient is 0.1, it is 3% of the original light intensity. Therefore, in the organic light emitting device 10 of the present embodiment, the light emitted from the center of the hole 17 does not become at least several percent or less of the original light intensity before entering the low refractive index layer 13. Transmission loss due to the conductive layer 14 is suppressed.

(Method for manufacturing organic light emitting device)
Next, a method for manufacturing an organic light emitting device to which the present embodiment is applied will be described taking the case of the organic light emitting device 10 described in FIG. 1-1 as an example.
16 (a) to 16 (f) are diagrams illustrating a method for manufacturing the organic light emitting device 10 to which the present exemplary embodiment is applied.
First, the anode layer 12 as the first electrode layer is formed on the substrate 11 (FIG. 16A: first electrode layer forming step), and then the insulating low refractive index layer 13 is formed on the anode layer 12. (FIG. 16B: Low refractive index layer forming step). In the present embodiment, a glass substrate is used as the substrate 11. Further, ITO is used as a material for forming the anode layer 12, and silicon dioxide (SiO ₂ ) is used as a material for forming the low refractive index layer 13.
In order to form the anode layer 12 and the low refractive index layer 13 on the substrate 11, a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, an ion plating method, a dry method such as a CVD method, a spin coating method, a dip coating, etc. A wet method such as a method, an inkjet method, a printing method, a spray method, or a dispenser method can be used.
In addition, the process of forming the anode layer 12 can be omitted by using a so-called electrode-attached substrate in which ITO is already formed as the anode layer 12 on the substrate 11.

Next, a hole 17 penetrating the low refractive index layer 13 formed in the step of FIG. 16B is formed (FIG. 16C: hole forming step).

As a method of forming the hole 17 in the low refractive index layer 13, for example, a method using lithography can be used. In order to do this, first, a resist solution is applied onto the low refractive index layer 13, and the excess resist solution is removed by spin coating or the like to form a resist layer. Next, when a mask on which a predetermined pattern for forming the hole 17 is formed is covered and exposed with ultraviolet (UV), electron beam (EB) or the like, the hole 17 is formed in the resist layer. A predetermined pattern corresponding to is exposed. Then, when the exposed portion of the resist layer is removed using a developer, the resist layer in the exposed pattern portion is removed. Thus, the surface of the low refractive index layer 13 is exposed corresponding to the exposed pattern portion.
Next, the exposed portion of the low refractive index layer 13 is etched away using the remaining resist layer as a mask. As the etching, either dry etching or wet etching can be used. In this case, the shape of the hole 17 can be controlled by combining isotropic etching and anisotropic etching. As dry etching, reactive ion etching (RIE) or inductively coupled plasma etching can be used. As wet etching, a method of immersing in dilute hydrochloric acid or dilute sulfuric acid can be used. The hole 17 is formed in the low refractive index layer 13 by removing the remaining resist layer with a resist removing solution or the like.

Further, the hole 17 can be formed by a nanoimprint method. Specifically, after forming the resist layer, a mask on which a predetermined convex pattern for forming a pattern is drawn is pressed against the surface of the resist layer while applying pressure. In this state, the resist layer is cured by irradiating the resist layer with heat and / or light. Next, by removing the mask, a pattern of the hole 17 corresponding to the convex pattern is formed on the resist layer surface. Subsequently, the hole 17 can be formed by performing the etching described above.

Next, a translucent conductive layer 14 that is formed at least in the hole 17 and is in electrical contact with the anode layer 12 is formed (FIG. 16D: translucent conductive layer forming step).
In order to form the translucent conductive layer 14, the same technique as that used to form the anode layer 12 and the low refractive index layer 13 can be used. However, when a layer containing a polymer organic compound is formed as the translucent conductive layer 14, a coating method is particularly preferable. When film formation is performed by a coating method, a coating solution in which the material constituting the translucent conductive layer 14 is dispersed in a predetermined solvent such as an organic solvent or water is applied. When applying, various methods such as spin coating, spray coating, dip coating, ink jet, slit coating, dispenser, and printing can be used. After the application, the translucent conductive layer 14 is formed by drying the application solution by heating or vacuuming.

The organic semiconductor layer 15 including the light emitting layer 15a is formed on the light-transmitting conductive layer 14 so that at least a part thereof enters the hole 17 (FIG. 16E: organic semiconductor layer forming step).
In order to form each layer constituting the organic semiconductor layer 15, the same technique as that used to form the translucent conductive layer 14 can be used.

Next, the cathode layer 16 that is the second electrode layer is formed on the organic semiconductor layer 15 (FIG. 16F: second electrode layer forming step).
In order to form the cathode layer 16, the same technique as that used to form the anode layer 12 and the low refractive index layer 13 can be used.
Further, when the light-transmitting conductive layer 14 and the organic semiconductor layer 15 are formed with a uniform thickness along the side surface of the hole portion 17 (as shown in FIGS. 4, 5, 6, 8, 9, and 11). In this case, dry methods (vacuum evaporation, electron beam evaporation, sputtering, ion plating, etc.) are used, and the particles of the component to be deposited are emitted obliquely from the evaporation source or target to the substrate surface. Thus, it is preferable to form the film while rotating the substrate.

The organic light emitting device 10 can be manufactured through the above steps.
In addition, it is preferable to use the organic light emitting element 10 stably for a long period of time and to attach a protective layer or a protective cover (not shown) for protecting the organic light emitting element 10 from the outside. As the protective layer, polymer compounds, metal oxides, metal fluorides, metal borides, silicon compounds such as silicon nitride and silicon oxide, and 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. It is preferable that the protective cover is sealed with a thermosetting resin or a photo-curing resin and bonded to the element substrate. In this case, it is preferable to use a spacer because a predetermined space can be maintained and the organic light emitting element 10 can be prevented from being damaged. If an inert gas such as nitrogen, argon or helium is sealed in this space, it becomes easy to prevent the upper cathode layer 16 from being oxidized. In particular, when helium is used, heat conduction is high, and thus heat generated from the organic light emitting element 10 when voltage is applied can be effectively transmitted to the protective cover, which is preferable. Further, by installing a desiccant such as barium oxide in this space, it becomes easy to suppress the moisture adsorbed in the series of manufacturing steps from damaging the organic light emitting element 10.

The organic light emitting device 10 of the present embodiment is suitably used for a display device as, for example, a matrix or segment pixel. Further, it can be suitably used as a surface emitting light source without forming pixels. Specifically, computers, televisions, mobile terminals, mobile phones, car navigation systems, signs, signboards, video camera viewfinders, display devices, backlights, electrophotography, illumination, resist exposure, readers, interior lighting, light It is suitably used for a surface emitting light source in a communication system or the like.

(Display device)
Next, a display device including the organic light emitting element 10 described in detail above will be described.
FIG. 17 is a diagram illustrating an example of a display device using the organic light emitting element 10 in the present embodiment.
The display device 200 shown in FIG. 17 is a so-called passive matrix display device, and includes a display device substrate 202, an anode wiring 204, an anode auxiliary wiring 206, a cathode wiring 208, an insulating film 210, a cathode partition wall 212, and the organic light emitting element 10. , A sealing plate 216, and a sealing material 218.

As the display device substrate 202, for example, a transparent substrate such as a rectangular glass substrate can be used. The thickness of the display device substrate 202 is not particularly limited, but for example, a thickness of 0.1 mm to 1 mm can be used.

A plurality of anode wirings 204 are formed on the display device substrate 202. The anode wirings 204 are arranged in parallel at a constant interval. The anode wiring 204 is made of a transparent conductive film, and for example, ITO (Indium Tin Oxide) can be used. The thickness of the anode wiring 204 can be set to 100 nm to 150 nm, for example. An anode auxiliary wiring 206 is formed on the end of each anode wiring 204. The anode auxiliary wiring 206 is electrically connected to the anode wiring 204. With this configuration, the anode auxiliary wiring 206 functions as a terminal for connecting to the external wiring on the end portion side of the display device substrate 202, and the anode auxiliary wiring 206 is connected from an external driving circuit (not shown). A current can be supplied to the anode wiring 204 through the wiring. The anode auxiliary wiring 206 is made of a metal film having a thickness of 500 nm to 600 nm, for example.

Further, a plurality of cathode wirings 208 are provided on the organic light emitting element 10. The plurality of cathode wirings 208 are arranged so as to be parallel to each other and orthogonal to the anode wiring 204. As the cathode wiring 208, Al or an Al alloy can be used. The thickness of the cathode wiring 208 is, for example, 100 nm to 150 nm. Further, similarly to the anode auxiliary wiring 206 for the anode wiring 204, a cathode auxiliary wiring (not shown) is provided at the end of the cathode wiring 208 and is electrically connected to the cathode wiring 208. Therefore, current can flow between the cathode wiring 208 and the cathode auxiliary wiring.

An insulating film 210 is formed on the display device substrate 202 so as to cover the anode wiring 204. The insulating film 210 is provided with a rectangular opening 220 so as to expose a part of the anode wiring 204. The plurality of openings 220 are arranged in a matrix on the anode wiring 204. In the opening 220, the organic light emitting element 10 is provided between the anode wiring 204 and the cathode wiring 208 as described later. That is, each opening 220 is a pixel. Accordingly, a display area is formed corresponding to the opening 220. Here, the film thickness of the insulating film 210 can be, for example, 200 nm to 300 nm, and the size of the opening 220 can be, for example, 300 μm × 300 μm.

The organic light emitting element 10 is formed at a location corresponding to the position of the opening 220 on the anode wiring 204. The organic light emitting device 10 is sandwiched between the anode wiring 204 and the cathode wiring 208 in the opening 220. That is, the anode layer 12 (see FIG. 1-1) of the organic light emitting device 10 is in contact with the anode wiring 204, and the cathode layer 16 (see FIG. 1-1) is in contact with the cathode wiring 208. The thickness of the organic light emitting element 10 can be set to, for example, 150 nm to 200 nm.

A plurality of cathode partitions 212 are formed on the insulating film 210 along a direction perpendicular to the anode wiring 204. The cathode partition 212 plays a role of spatially separating the plurality of cathode wirings 208 so that the wirings of the cathode wirings 208 do not conduct with each other. Accordingly, the cathode wiring 208 is disposed between the adjacent cathode partition walls 212. As the size of the cathode partition wall 212, for example, a cathode partition with a height of 2 to 3 μm and a width of 10 μm can be used.

The display device substrate 202 is bonded through a sealing plate 216 and a sealing material 218. Thereby, the space in which the organic light emitting element 10 is provided can be sealed, and the organic light emitting element 10 can be prevented from being deteriorated by moisture in the air. As the sealing plate 216, for example, a glass substrate having a thickness of 0.7 mm to 1.1 mm can be used.

In the display device 200 having such a structure, a current is supplied to the organic light emitting element 10 by a driving device (not shown) via the anode auxiliary wiring 206 and the cathode auxiliary wiring (not shown), and the light emitting layer 15a (see FIG. 1-1). Can emit light and emit light. An image can be displayed on the display device 200 by controlling light emission and non-light emission of the organic light emitting element 10 corresponding to the above-described pixel by the control device.

(Lighting device)
Next, a lighting device using the organic light emitting element 10 of the present embodiment will be described.
FIG. 18 is a diagram illustrating an example of an illumination device including the organic light emitting element 10 according to the present embodiment.
The lighting device 300 shown in FIG. 18 includes the organic light emitting element 10 described above, and a terminal 302 that is installed at one end of the substrate 11 of the organic light emitting element 10 and connected to the anode layer 12 (see FIG. 1-1). The terminal 303 installed at the other end of the substrate 11 and connected to the cathode layer 16 (see FIG. 1-1) of the organic light emitting device 10 is connected to the terminal 302 and the terminal 303 to drive the organic light emitting device 10. And a lighting circuit 301 for the purpose.

The lighting circuit 301 has a DC power source (not shown) and a control circuit (not shown) inside, and supplies a current between the anode layer 12 and the cathode layer 16 of the organic light emitting element 10 through the terminal 302 and the terminal 303. Then, the organic light emitting device 10 is driven to cause the light emitting layer 15a (see FIG. 1-1) to emit light, and the substrate from the hole 17 (see FIG. 1-1) and the low refractive index layer 13 (see FIG. 1-1). 11, light is emitted and used as illumination light. The light emitting layer 15a may be made of a light emitting material that emits white light, and the organic light emitting element 10 using a light emitting material that emits green light (G), blue light (B), and red light (R). A plurality of them may be provided, and the combined light may be white. In the illumination device 300 of the present embodiment, when light is emitted with the diameter and interval of the hole portions 17 being reduced, it appears that surface light is emitted to the human eye.

DESCRIPTION OF SYMBOLS 10,100 ... Organic light emitting element, 11 ... Board | substrate, 12 ... Anode layer, 13 ... Low refractive index layer, 14 ... Translucent conductive layer, 15 ... Organic-semiconductor layer, 15a ... Light emitting layer, 16 ... Cathode layer, 17 ... Hole, 200 ... display device, 300 ... lighting device

Claims

A first electrode layer formed on the substrate;
An insulating low refractive index layer formed on the first electrode layer;
A hole formed through at least the low refractive index layer;
A translucent conductive layer formed only along the entire bottom surface of the hole, or at least along the entire bottom surface and side surface of the hole, and formed in electrical contact with the first electrode layer;
An organic semiconductor layer that includes a light emitting layer, is formed on the translucent conductive layer, and is formed so that at least part of the hole enters the hole portion;
A second electrode layer formed on the organic semiconductor layer;
With
The low refractive index layer has a refractive index smaller than that of the translucent conductive layer and the organic semiconductor layer,
The maximum width when the hole is viewed in plan is 3 μm or less,
The organic semiconductor layer is formed with a uniform thickness at a position where the hole is formed.
2. The organic light emitting device according to claim 1, wherein the light emitting layer of the organic semiconductor layer is formed so that at least part of the light emitting layer enters the hole.
3. The organic material according to claim 1, wherein a surface of the translucent conductive layer on the organic semiconductor layer side has a shape that is recessed toward the first electrode layer at a position where the hole is formed. Light emitting element.
4. The organic light emitting device according to claim 3, wherein the shape recessed on the first electrode layer side is a curved shape.
The organic light-emitting element according to any one of claims 1 to 4, wherein the translucent conductive layer is formed to extend on the low refractive index layer.
The organic light-emitting element according to claim 1, wherein the translucent conductive layer is formed with a uniform thickness along the inner surface of the hole.
The first electrode layer reflects light emitted from the light emitting layer of the organic semiconductor layer, and the second electrode layer transmits light emitted from the light emitting layer. The organic light emitting element of any one of these.
7. The first electrode layer transmits light emitted from the light emitting layer of the organic semiconductor layer, and the second electrode layer reflects light emitted from the light emitting layer. The organic light emitting element of any one of these.
The organic light emitting device according to claim 8, wherein the hole is formed by further drilling at least a part of the first electrode layer.
10. The organic light emitting device according to claim 9, wherein the hole is formed by further drilling a part of the substrate.
A first electrode layer forming step of forming a first electrode layer on the substrate;
A low refractive index layer forming step of forming an insulating low refractive index layer on the first electrode layer;
A hole forming step of forming a hole having a maximum width of 3 μm or less when penetrating at least through the low refractive index layer;
A translucent conductive layer forming step of forming a translucent conductive layer formed at least inside the hole portion and in electrical contact with the first electrode layer by a coating method;
An organic semiconductor layer forming step of forming an organic semiconductor layer including a light emitting layer on the translucent conductive layer so that at least part of the hole enters the inside of the hole;
A second electrode layer forming step of forming a second electrode layer on the organic semiconductor layer;
With
The method for manufacturing an organic light-emitting element, wherein the low refractive index layer has a refractive index smaller than those of the translucent conductive layer and the organic semiconductor layer.
A display device comprising the organic light-emitting element according to any one of claims 1 to 10.
A lighting device comprising the organic light-emitting element according to any one of claims 1 to 10.