JPH1187056A - Manufacture of optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an optical element wherein an amorphous luminous layer can be formed surely with good controllability even in the case of using a luminous material or the like such as one which decomposes partly when it is vaporized. SOLUTION: A luminous layer has a stratified region containing a host luminous material and guest luminous material, the host luminous material has a vaporization temperature higher than that of the guest luminous material, and of electron/hole transportability at least the electron transportability is provided in an optical element, in a method of its manufacture by using a physical gas phase growth device 40 provided with a luminous material storage vessel (heating board) 30, so as to prevent mixing of the host luminous material with the guest luminous material, and so as to bring the host/guest luminous material into contact, after the host/guest luminous material is stored in the luminous material storage vessel 30, by heating it, the stratified region of the luminous layer is formed by the physical gas phase growth method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical element, for example, a self-luminous flat display device, and particularly suitable for an organic electroluminescent display device using an organic material layer as an electroluminescent layer. More specifically, the present invention relates to a method for manufacturing an organic electroluminescent device.

[0002]

2. Description of the Related Art In recent years, the importance of interfaces between humans and machines, including multimedia-oriented products, has been increasing. In order for humans to operate the machine more comfortably and efficiently, it is necessary to extract information from the machine to be operated in a simple, instant, and sufficient amount without errors.
For this purpose, various display devices have been studied. In addition, with the miniaturization of machines, miniaturization of display elements,
The demand for thinner is increasing every day.

[0003] For example, there has been a remarkable progress in miniaturization of laptop information processing devices, such as notebook personal computers and notebook word processors, which are integrated with display elements. The innovation in the equipment is also wonderful. 2. Description of the Related Art Today, liquid crystal display devices are used as interfaces for various products, and are often incorporated in products used everyday, such as small-sized televisions, watches, and calculators, as well as laptop-type information processing devices. Liquid crystal display devices have been studied as the interface between humans and machines, from small display devices to large-capacity display devices, as the center of display elements, taking advantage of the characteristics of liquid crystal driven at low voltage and low power consumption. ing.

However, since the liquid crystal display device is not self-luminous, a backlight is required, and driving this backlight requires more power than driving a liquid crystal. As a result, the use time of the built-in storage battery or the like is shortened, and there is a limitation in use. Furthermore, the liquid crystal display device is not suitable for a large-sized display device because the viewing angle is narrow, and since the display method depends on the alignment state of the liquid crystal molecules, the contrast varies depending on the angle even in the viewing angle. There is also a big problem that it will.

In view of the driving method, the active matrix method, which is one of the driving methods, has a sufficient response speed to handle moving images, but uses a TFT (thin film transistor) driving circuit, so that the pixel driving method is difficult. It is difficult to increase the screen size due to defects. Also, using a TFT drive circuit is not preferable from the viewpoint of reducing the manufacturing cost of the liquid crystal display device. The simple matrix method, which is another driving method, has a low manufacturing cost and a relatively large screen size is relatively easy. However, there is a problem that the response speed is not sufficient to handle moving images.

On the other hand, as a self-luminous display element,
Plasma display devices, inorganic electroluminescent devices, organic electroluminescent devices, and the like have been studied.

A plasma display element is an application of plasma emission in a low-pressure gas to a display, and is suitable for an increase in size and capacity, but has problems in terms of thinning and manufacturing cost. . Further, since a high voltage AC bias is required for driving, it is not suitable for incorporation into portable equipment. As the inorganic electroluminescent device, a green light emitting display device or the like has been commercialized. However, like the plasma display device, it is driven by an AC bias, and requires several hundred volts for driving, and it is difficult to achieve full color. It appears to be.

On the other hand, since the discovery of a light-emitting phenomenon caused by carrier injection into an anthracene single crystal that generates strong fluorescence in the early 1960's, the electroluminescence phenomenon of organic compounds, a kind of electroluminescence phenomenon, has been studied for a long time. It has been. However, with low brightness, single color,
Moreover, since it is a single crystal, only basic research on carrier injection into an organic material has been conducted.

However, since Tang et al. Of Eastman Kodak Company in 1987 introduced an organic thin-film electroluminescent device having a laminated structure having an amorphous light-emitting layer capable of driving at a low voltage and emitting light at a high luminance, (R, G, Research and development on the light emission of three primary colors (B), stability, increase in brightness, laminated structure, manufacturing method, etc. are being actively conducted in various fields. Furthermore, various organic materials, which are features of organic materials, have been developed by molecular design and the like, and have been applied to color display devices of organic electroluminescent devices having excellent features such as low-voltage DC drive, thinness, and self-luminous properties. Applied research is also being actively conducted.

The organic electroluminescent element has a film thickness of 1 μm or less, and is ideal as a self-luminous display element, such as converting electric energy into light energy by injecting a current to emit light in a planar manner. have.

An example of a conventional organic electroluminescent device is shown in a schematic sectional view of FIG. This organic electroluminescent device 1
Reference numeral 00 denotes an anode (transparent electrode) 112 made of an ITO (Indium Tin Oxide) film, a hole (hole) transport layer 114, a light emitting layer 120, an electron transport layer 115, and a cathode (transparent substrate 111 made of, for example, a glass substrate). It is manufactured by sequentially forming a film of, for example, an aluminum electrode 116 by, for example, a vacuum evaporation method. The hole transport layer 114 and the light emitting layer 1
20 and the electron transport layer 115 are made of an organic material. Then, a DC voltage is selectively applied between the anode 112 and the cathode 116, which are transparent electrodes, so that holes injected as carriers from the anode 112 are transferred to the hole transport layer 114.
Then, the electrons injected from the cathode 116 move through the electron transport layer 115, and recombination of electrons and holes occurs in the light emitting layer 120. As a result, light emission of a predetermined wavelength occurs in the light emitting layer 120, and this light emission can be observed from the transparent substrate 111 side. As the light emitting layer 120, for example, light emission of an anthracene-based compound, a naphthalene-based compound, a phenanthrene-based compound, a pyrene-based compound, a chrysene-based compound, a perylene-based compound, a butadiene-based compound, a coumarin-based compound, an acridine-based compound, a stilbene-based compound, or the like Substances can be used. Note that these light-emitting substances may be contained in the electron-transport layer 115.

Another example of a conventional organic electroluminescent device is shown in FIG.
(B) is a schematic cross-sectional view. In the organic electroluminescent device 100A, the light emitting layer 120 is omitted,
The electron transport layer 115 also serves as a light emitting layer, and has a structure in which the electron transport layer 115 itself or the guest material emits light by using the above-described fluorescent substance as a guest material.

FIG. 9 schematically shows a specific example of such an organic electroluminescent device. That is, each organic thin film layer (the hole transport layer 1
14, a laminate of the light-emitting layer 120 and the electron transport layer 115) is disposed between the cathode 116 and the anode 112, and these electrodes are arranged in stripes and intersected in a matrix with the laminate interposed therebetween. I do. And these electrodes,
A luminance signal circuit 117 and a control circuit 118 with a built-in shift register apply a signal voltage in a time series to emit light at a plurality of intersection positions (pixels).
With such a configuration, it can be used not only as a display device but also as an image reproducing device. By arranging the above-mentioned striped electrodes in an appropriate pattern for each color of red (R), green (G), and blue (B), it is possible to constitute a full-color or multi-color display device. it can. As described above, in the display device including a plurality of pixels using the organic electroluminescent element, the organic thin film layers 115, 120, and 114 are sandwiched between the anode (transparent electrode) 112 and the cathode (metal electrode). And emits light toward the anode 112 side.

[0014]

SUMMARY OF THE INVENTION In the application of an organic electroluminescent device to a color display device, (R, G, B)
The stable emission of the three primary colors is an essential requirement. However, at the current stage, other than the green luminescent material,
There are no reports on light-emitting materials (red and blue light-emitting materials) that can be applied to display devices and have sufficient stability, chromaticity, luminance, etc., and are being studied in various fields. is there. At present, aluminum-quinoline complexes, which are promising green light-emitting materials, have slightly shifted chromaticity. Therefore, it is ideally desirable that the light-emitting layer be composed of a single-layer organic material and emit light. However, in reality, the light-emitting layer emits light from the host light-emitting material and the guest light-emitting material in order to improve chromaticity and luminance. It is essential to form a layer (host-guest light emitting layer) and adjust the composition of the light emitting layer. In addition, the host light emitting material means a main light emitting material, and the guest light emitting material means a light emitting material added to the host light emitting material.

By the way, a vacuum deposition method is often used in the process of manufacturing an organic electroluminescent element, and a light-emitting layer is formed by binary deposition (co-deposition) based on a host light-emitting material and a guest light-emitting material in a vacuum integrated process. To do so, at least two types of deposition sources are required, and
When an organic electroluminescent device is manufactured by laminating an electron transporting layer, a hole transporting layer, and a cathode, it is necessary to use a vacuum evaporation apparatus having a large number of evaporation sources.

Further, when an application to a full-color display device using an organic electroluminescent device is attempted, even if the electron transport layer, the hole transport layer, and the cathode are formed using a common material, (R, Six types of deposition sources are required to form three types of light emitting layers composed of a host light emitting material and a guest light emitting material for the three primary colors G and B). Therefore, it is difficult to produce a full-color display device by a vacuum integrated process from the viewpoint of a vacuum deposition device.

Considering these problems, if a host luminescent material and a guest luminescent material are stored in the same luminescent material storage container of a vacuum deposition apparatus, an amorphous luminescent layer that emits light stably can be formed. , It is possible to produce a full-color display device using an organic electroluminescent device by an integrated vacuum process, and
The burden on manufacturing facilities is also reduced.

An organic electroluminescent device having various characteristics can be used as a guest light emitting material if a light emitting material having a high fluorescence yield and being easily decomposed during vapor deposition or a light emitting material having no sublimation property can be used. Can be manufactured.

Therefore, an object of the present invention is to form an amorphous light emitting layer that emits light stably when the host light emitting material and the guest light emitting material are stored in the same light emitting material storage container of the physical vapor deposition apparatus. It is another object of the present invention to provide a method of manufacturing an optical element which can form an amorphous light emitting layer reliably and with good controllability.

[0020]

According to a first aspect of the present invention, there is provided a method of fabricating an optical element, comprising: an organic material layer including a light emitting layer sandwiched between an anode and a cathode. The light-emitting layer has a layered region containing a host light-emitting material and a guest light-emitting material having an emission wavelength different from the emission wavelength of the host light-emitting material. The material has a higher vaporization temperature than the guest light emitting material, and has an optical element having at least an electron transporting property of an electron transporting property and a hole transporting property. This is a method of manufacturing using a growth apparatus. In addition, the method for manufacturing an optical element according to the second aspect of the present invention for achieving the above object has a structure in which an organic material layer including a light-emitting layer is sandwiched between an anode and a cathode, The light-emitting layer has a layered region containing a host light-emitting material and a guest light-emitting material having a light-emitting wavelength different from the light-emitting wavelength of the host light-emitting material. A method for producing an optical element having a low vaporization temperature and having at least a hole transporting property of an electron transporting property and a hole transporting property by using a physical vapor deposition apparatus provided with a luminescent material storage container. It is. In the method for manufacturing an optical element according to the first or second aspect of the present invention, the host light emitting material and the guest light emitting material are in contact with each other so that the host light emitting material and the guest light emitting material are not mixed. As described above, after the host light emitting material and the guest light emitting material are stored in the light emitting material storage container, the layered region of the light emitting layer is formed by physical vapor deposition by heating the light emitting material storage container. It is characterized by.

In the method for manufacturing an optical element according to the first aspect of the present invention, the content of the guest light emitting material in the light emitting layer is gradually reduced from the anode side to the cathode side of the light emitting layer. Alternatively, from the anode side to the cathode side of the light emitting layer, a layered region containing a guest light emitting material as a main component, the layered region containing a host light emitting material and a guest light emitting material, and a host light emitting material as a main component. Are sequentially formed by a physical vapor deposition method. In the method for manufacturing an optical element according to the second aspect of the present invention, the content of the guest light emitting material in the light emitting layer may be gradually increased from the anode side to the cathode side of the light emitting layer. Can or alternatively, from the anode side to the cathode side of the light emitting layer, a layered region containing a host light emitting material as a main component, the layered region containing a host light emitting material and a guest light emitting material, a guest light emitting material as a main component The layered regions to be formed may be sequentially formed by physical vapor deposition. In order to gradually change the content of the guest light emitting material in the light emitting layer in the thickness direction of the light emitting layer, for example, the evaporation rate may be controlled.

In the method for manufacturing an optical element according to the first or second aspect of the present invention, the light emitting layer may have a desired guest light emitting material content in the thickness direction. In order to have a desired guest light emitting material content, the combination of the host light emitting material and the guest light emitting material and the order of vaporization may be appropriately selected.

As the physical vapor deposition apparatus, a vacuum vapor deposition apparatus can be exemplified, and a physical vapor deposition method (PVD) is used.
Examples of the method include a vacuum deposition method, but the method is not limited thereto. In this specification, vaporization is a concept that includes sublimation in which a solid directly becomes a gas and evaporation in which a liquid becomes a gas, or evaporation in which a solid becomes a liquid and then becomes a gas. Note that as the guest light emitting material, a material that partially decomposes during vaporization, or a material that does not have sublimability can be used.

By changing the content of the guest light emitting material in the light emitting layer gradually in the thickness direction of the light emitting layer, or by providing a structure having a desired guest light emitting material content in the thickness direction of the light emitting layer, The chromaticity of the emission spectrum of the optical element can be changed depending on the voltage applied to the optical element. That is, as the applied voltage increases, the emission center (recombination center) in the light emitting layer shifts, for example, from the anode side to the cathode side, so that the chromaticity of the emission spectrum of the optical element changes. Accordingly, light having various wavelengths can be emitted by one optical element, and the chromaticity of the emission spectrum can be controlled by the applied voltage.

In the method of manufacturing an optical element according to the first aspect of the present invention, the structure of the optical element is such that the anode is made of a transparent electrode, the cathode is made of a metal electrode, and the organic material layer is made from the anode side. A single-hetero structure in which a hole transport layer and a light-emitting layer also serving as an electron transport layer are laminated, or, alternatively, the anode is formed of a transparent electrode, the cathode is formed of a metal electrode, and the organic material layer is formed from the anode side. A double hetero structure in which a hole transport layer, a light-emitting layer, and an electron transport layer are stacked,
Can be mentioned.

On the other hand, in the method for fabricating an optical element according to the second aspect of the present invention, the structure of the optical element is such that the anode comprises a transparent electrode, the cathode comprises a metal electrode, and the organic material layer comprises an anode. From the side, a single heterostructure in which a light emitting layer also serving as a hole transport layer and an electron transport layer are laminated, or the anode is made of a transparent electrode, the cathode is made of a metal electrode, and the organic material layer is an anode From the side, a double hetero structure in which a hole transport layer, a light emitting layer, and an electron transport layer are stacked,
Can be mentioned.

With the above-described structure of the optical element, an organic electroluminescent element can be formed, and can be applied to, for example, a color display device.

The anode is preferably composed of a transparent electrode made of an ITO film, for example, in order to efficiently extract light emitted from the light emitting layer. In addition, in order to inject holes efficiently, a work from a vacuum level is required. Gold (Au) which is a material having a large function, a mixture of tin dioxide and antimony (SnO ₂ +
Sb), a mixture of zinc oxide and aluminum (ZnO + A
1). On the other hand, the cathode is made of aluminum (Al), indium (In), magnesium (Mg), silver (Ag), calcium (Ca), barium (Ba), lithium (L) having a low work function from the vacuum level.
i), etc., or an alloy of these and other metals.

The hole transporting layer can be composed of a known organic compound having a hole transporting property such as a biphenyl compound, a benzidine derivative, a styrylamine derivative, a triphenylmethane derivative, a hydrazone derivative and the like.
On the other hand, the electron transporting layer can be composed of a known organic compound having an electron transporting property such as a perylene derivative, a bisstyryl derivative, and a pyridine derivative.

In the present invention, the host light-emitting material and the guest light-emitting material are stored in one light-emitting material so that the host light-emitting material and the guest light-emitting material are not mixed and the host light-emitting material and the guest light-emitting material are in contact with each other. When the luminescent material storage container is heated by heating the luminescent material storage container to form a layered region of the luminescent layer by physical vapor deposition,
Even if the guest light emitting material is a material that partially decomposes during vaporization, the guest light emitting material can be reliably prevented from decomposing. Even if the guest material does not have sublimability, the guest material can be sublimated together with the sublimation of the host material. That is, for example, by combining a guest light emitting material, which is difficult to form a film by physical vapor deposition because it is decomposed alone, with a highly light emitting host light emitting material, the guest light emitting material is also decomposed as the host light emitting material is vaporized. This makes it possible to vaporize without performing any process, and to form a light emitting layer composed of two kinds of light emitting materials by a physical vapor deposition method. The luminescent material storage container is heated in a state where the host luminescent material and the guest luminescent material are stored in separate luminescent material storage containers, or in a state where these materials are mixed and stored in the luminescent material storage container. When the layered region of the light-emitting layer is formed by physical vapor deposition, if the guest light-emitting material is a material that partially decomposes during vaporization, the guest light-emitting material is decomposed, resulting in the light-emitting layer Is extremely difficult to form.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

Example 1 Example 1 relates to a method for manufacturing an optical element according to the first aspect of the present invention. FIG. 4A is a schematic cross-sectional view of an organic electroluminescent device, which is an optical device according to the first embodiment. This optical element 10 has a structure in which an organic material layer 13 including a light emitting layer 20 is sandwiched between an anode 12 and a cathode 16. And the light emitting layer 20
It has a layered region 22 containing a host light emitting material and a guest light emitting material having an emission wavelength different from the emission wavelength of the host light emitting material. Also, the host luminescent material is
It has a higher vaporization temperature than the guest light emitting material and has an electron transporting property. Incidentally, the optical element in the first embodiment is:
The organic material layer 13 is disposed on the hole transport layer 14 from the anode 12 side.
And a light-emitting layer 20 also serving as an electron transport layer having a single hetero structure. Note that the light emitting layer 20 is in an amorphous state.

In Example 1, tris (8-quinolinol) aluminum (abbreviated as Alq ₃ ), which is an aluminum-quinoline complex having an electron transporting property, was used as a host light emitting material constituting the light emitting layer. In addition, DCM2 generally used as a laser dye was used as a guest light emitting material. The light-emitting layer 20 includes a layered region 21 (hereinafter, sometimes referred to as a first layered region) containing a guest light-emitting material as a main component, from the anode side to the cathode side of the light-emitting layer 20.
A layered region 22 containing a host light emitting material and a guest light emitting material (sometimes referred to as a second layered region), and a layered region 23 mainly containing the host light emitting material (sometimes referred to as a third layered region), It is formed sequentially by physical vapor deposition. The structural formulas of Alq ₃ and DCM2 are represented by the following formula (1)
And equation (2).

[0034]

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[0035]

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Further, the anode 12 is composed of a transparent electrode made of an ITO film, and the cathode 16 is composed of a metal electrode (aluminum electrode). In Example 1, the hole transport layer 14 was formed by NN′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diamino having a structural formula represented by the following formula (3). It was formed from biphenyl (abbreviated as TPD).

[0037]

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In the first embodiment, such an optical element is manufactured by using a physical vapor deposition apparatus (in the first embodiment, a vacuum evaporation apparatus) provided with a light-emitting material storage container.
At this time, the host light emitting material and the guest light emitting material are stored in the light emitting material storage container so that the host light emitting material and the guest light emitting material are not mixed, and the host light emitting material is in contact with the guest light emitting material. By heating the material storage container, the layered regions 21, 22, 23 of the light emitting layer 20 are formed.
By physical vapor deposition (in Example 1, vacuum deposition)
Formed at

Specifically, a physical vapor deposition apparatus 40 which is a vacuum evaporation apparatus as schematically shown in FIG. 1, and a heating boat 30 (a luminous material storage container) schematically shown in FIGS. Is used). Physical vapor deposition apparatus 4
Numeral 0 is composed of support arms 41 and 42, shutter 44, shutter support shaft 45, a vacuum exhaust device, a resistor for heating the heating boat 30, and a power supply (these are not shown). Further, a stage (not shown) for mounting the evaporation mask 43 and the transparent substrate 11 is provided below the support arm 42. The transparent substrate 11 is placed on this stage with the anode 12 facing down, the mask 43 for vapor deposition is set, and the heating boat 30 is heated by controlling the heat generated by a resistor (not shown) by a power supply. Thereby, the host luminescent material and / or the guest luminescent material stored in the heating boat 30 are vaporized (sublimated),
It is deposited on the transparent substrate 11. The heating method of the heating boat 30 may be an electron beam heating method instead of the resistance heating method. Note that the shutter 44 can be opened and closed by rotating the shutter 44 about the shutter support shaft 45, whereby the deposition of the luminescent material on the transparent substrate 11 can be controlled. The required number of heating boats 30 are arranged in the physical vapor deposition apparatus 40, one of which is shown in FIG.

FIG. 2A shows a schematic sectional view of the heating boat 30, and FIG. 2B shows an exploded perspective view. The heating boat 30 is made of tantalum (Ta), and includes a main body 31 and a lid 32. The main body 31 is provided with a concave portion 31A. The lid 32 is provided with an opening 33, and the vaporized host luminescent material and / or guest luminescent material flows out of the opening 33 singly or in a mixed state. FIG. 3A is a schematic cross-sectional view showing a state in which the host light emitting material and the guest light emitting material are stored in the heating boat 30, and FIG. 3B is a perspective view of the main body 31. The host light emitting material and the guest light emitting material are accommodated in the heating boat 30 so that they do not mix with each other and come into contact with each other. In order to make such a storage state, for example, the host luminescent material is placed in the concave portion 3 from the left hand side of the main body 31 in FIG.
1A, and on the other hand, the guest luminescent material may be packed into the recess 31A from the right hand side.

Hereinafter, the heating boat 3 corresponding to the physical vapor deposition apparatus 40 and the luminous material storage container shown in FIGS.
A method for fabricating the optical element of Example 1 using No. 0 will be described.

[Step-100] In the first embodiment, first, an ITO film having a thickness of about 0.1 μm is formed on the surface of a transparent substrate 11 made of glass having a size of 30 mm × 30 mm by a vacuum evaporation method. , An anode 12 composed of a transparent electrode (size:
2 mm x 2 mm). Then, an SiO ₂ film is formed on the entire surface of the anode 12 by a sputtering method, and the SiO ₂ film is patterned into a predetermined pixel pattern to form an S ₂ film.
A plurality of openings were formed in the iO ₂ film, and a prototype substrate in which a region other than the region of the anode 12 exposed at the bottom of the opening was covered with the SiO ₂ film was manufactured. FIG. 4A shows such S
Illustration of the iO ₂ film is omitted. The anode 12 may be patterned into the shape shown in FIG.

[Step-110] Next, the transparent substrate 11 is placed on the stage of the physical vapor deposition apparatus 40 shown in FIG.
2 is placed downward, and the anode 12 is formed by a physical vapor deposition method (specifically, a vacuum deposition method) using a deposition mask 43.
A hole transport layer 14 made of TPD having a thickness of about 50 nm was formed thereon. The film formation rate was 0.2 to 0.4 nm / sec.
Although the heating boat containing the TPD is disposed in the physical vapor deposition apparatus 40, the illustration of the heating boat is omitted.

[Step-120] Subsequently, FIGS. 2 and 3
The light emitting layer 20 was formed by a physical vapor deposition method (specifically, a vacuum deposition method) using the heating boat 30 shown in FIG. 1 and the physical vapor deposition apparatus 40 shown in FIG. The host light-emitting material and the guest light-emitting material are supplied to the heating boat 30 so that the host light-emitting material Alq ₃ and the guest light-emitting material DCM2 are not mixed and the host light-emitting material and the guest light-emitting material are in contact with each other. It was stored (see FIG. 3). The weight ratio between Alq ₃ and DCM 2 stored in the heating boat 30 is 6
/ 1.

Then, the heating boat 30 is heated, the shutter 44 is opened, the heating boat 30 is continuously heated, and the temperature of the heating boat 30 is gradually increased to a total film thickness of about 50 nm.
Of the light emitting layer 20 was formed. Deposition rate of 0.2-0.4n
m / sec.

If the temperature of the heating boat 30 is gradually increased by such an operation, first, the DC having a low sublimation temperature
M2 is mainly sublimated to form the guest light emitting material DCM
A layered region (first layered region) 21 mainly composed of 2 is formed. Layered region 21 mainly composed of guest light emitting material
Is almost DCM at the interface with the hole transport layer 14.
The ratio of DCM2 in the components of the layered region 21 decreases as the distance from the interface with the hole transport layer 14 decreases, but the ratio of DCM2 is still high.

Thereafter, Alq ₃ having a high sublimation temperature also starts sublimating, and a layered region (second layered region) containing Alq _{3 as} a host light emitting material and DCM2 as a guest light emitting material.
22 are formed. Further, when the temperature of the heating boat 30 is gradually increased, the host light emitting material A
A layered region (third layered region) 23 containing lq ₃ as a main component is formed. This layered region 23 has an electron transporting property.

Through these steps, the content of the guest light emitting material in the light emitting layer 20 is reduced.
Can be a structure in which the content of the guest light emitting material in the light emitting layer 20 is gradually reduced from the anode side to the cathode side of the light emitting layer 20; Alternatively, the light emitting layer can have a structure having a desired guest light emitting material content in the thickness direction. In addition, by changing the weight ratio between the host light emitting material and the guest light emitting material stored in the heating boat 30, the amount of the guest light emitting material doped into the host light emitting material can be controlled. Therefore, it is possible to produce optical elements having various light emitting layer structures, and as a result, optical elements having various light emitting wavelengths can be obtained, so that a desired light emitting wavelength can be obtained from a wide range of light emitting wavelength regions. .

Incidentally, if sublimation is performed before opening the shutter 44, as shown in a schematic sectional view of FIG.
An optical element having a structure in which the formation of the layered region (first layered region) 21 mainly including the guest light emitting material DCM2 is omitted. With such a structure, optical elements having different emission wavelengths can be manufactured.

As shown in a schematic cross-sectional view of FIG. 5A, the organic material layer 13 is formed by the hole transport layer 14, the light emitting layer 20, the electron transport layer 15, Can be fabricated to form an optical element having a double heterostructure. When manufacturing an optical element having such a double hetero structure, the shutter 44 is opened, the film forming speed is set to 0.2 to 0.4 nm / sec, and the
A 0 nm light emitting layer is formed. As a result, first, the DCM 2 having a low sublimation temperature mainly sublimates to form a layered region (first layered region) 21 mainly composed of the guest light emitting material DCM 2. Then, Alq with high sublimation temperature
₃ also begins to sublime, and a layered region (second layered region) 22 containing Alq _{3 as} a host light emitting material and DCM2 as a guest light emitting material is formed. Thereafter, the shutter 44 is closed, and the host light emitting material and the guest light emitting material are sublimated (empty sublimation) by a thickness of about 30 nm while keeping the film forming speed. Next, the film formation rate is set to 0.2 to 0.4.
The shutter 44 is re-opened to a thickness of about 2 nm / sec.
An electron transport layer 15 having a thickness of 0 nm is further formed. That is, by performing the empty sublimation, almost only the host luminescent material remains in the heating boat 30, and the electron transport layer 15 made of Alq ₃ can be formed. The first layered area 21
After the formation of the second layered region 22, the shutter 44 is closed and the Alq ₃ or G stored in another heating boat is closed.
by vacuum-depositing heated aq _3, it may form an electron transport layer 15 on the second layer region 22. Alternatively, as shown in a schematic cross-sectional view of FIG. 5B, after the above-mentioned third layered region 23 is formed, Alq ₃ or Gaq ₃ housed in another heating boat is heated and vacuum deposited. By doing so, the electron transport layer 1
5 may be formed.

[Step-130] Thereafter, a film thickness of about 0.2 μm
A cathode 16 made of aluminum was formed on the light emitting layer 20 by a vacuum evaporation method. The deposition rate is 1.1 to 1.3 n
m / sec. Note that the cathode 16 may be patterned into the shape shown in FIG.

When the characteristics of the organic electroluminescent device 10 as an optical device that emits red light were measured, the maximum emission wavelength was 635 n at an applied voltage of 8 volts.
m. In addition, the shape of the spectrum revealed that DCM2 was the emission center. At an applied voltage of 14 volts, a luminance of about 100 cd / m ² could be obtained. In this optical element 10, the hole transport layer 1 made of TPD was obtained from the measurement result of the spectrum.
DCM 2 is specifically Al near the interface between the light emitting layer 4 and the light emitting layer 20.
It has been found that the light-emitting layer 20 doped in the q ₃ are formed. In addition, a value of (0.68, 0.32) was shown on the CIE chromaticity coordinates.

In the amorphous light emitting layer 20, a layered region having a high guest light emitting material content and a layered region having a high host light emitting material content are formed as the light emitting material evaporates. Therefore, the layered region having a high content of the host luminescent material also functions as the electron transport layer, and the layered region having a high content of the guest luminescent material can generate a unique light emission. The wavelength can be changed. Accordingly, a single optical element can emit light of high modulation and high modulation by the guest light emitting material. In addition, the light-emitting layer 20 can be formed easily and continuously in a short time, easily and continuously using one light-emitting material storage container in one physical vapor deposition apparatus. Therefore, it is not necessary to particularly modify the existing physical vapor deposition apparatus.

(Embodiment 2) Embodiment 2 is a modification of Embodiment 1. In Example 2, me-DCM2 represented by the following formula (4) was used as the guest light emitting material.
In addition, a host light emitting material, a material constituting the hole transport layer 14,
The materials constituting the anode 12 and the cathode 16 were the same as in Example 1. The physical vapor deposition apparatus 40 and the heating boat 30, which are the vacuum evaporation apparatuses used, were the same as in Example 1.

[0055]

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Me-DCM2 is a material that partially decomposes during sublimation. That is, when me-DCM2 is stored alone in the light-emitting material storage container and the light-emitting material storage container is heated, the methyl group in the side chain is released in a part of me-DCM2. When film formation is performed in this state, me-DC
Instead of forming a light-emitting layer containing M2, me-
A light emitting layer containing DCM2 and DCM2 is formed. Thus, for example, the formation of the light-emitting layer containing Alq ₃ and me-DCM2, be carried out in a state of being accommodated separately Alq ₃ and me-DCM2 two luminescent material container is extremely difficult. In Example 2, as schematically shown in FIG. 3, the host light emitting material and the guest light emitting material are stored in a light emitting material storage container so that they are not mixed and that they are in contact with each other. , M
When e-DCM2 is vaporized, it is possible to reliably suppress a part of me-DCM2 from being decomposed.

Hereinafter, the physical vapor deposition apparatus 40 shown in FIGS. 1 to 3 and the heating boat 3 corresponding to the luminous material storage container will be described.
A method for manufacturing the optical element of Example 2 using 0 will be described.

[Step-200] In Example 2, a prototype substrate having the same structure as in Example 1 was produced.

[Step-210] Next, using the physical vapor deposition apparatus 40 shown in FIG. 1, a physical vapor deposition method (specifically, a vacuum deposition method) About 50nm
The hole transport layer 14 made of TPD was formed. In addition, the film formation rate was set to 0.2 to 0.4 nm / sec.

[Step-220] FIGS. 2 and 3
The light emitting layer 20 was formed by a physical vapor deposition method (specifically, a vacuum deposition method) using the heating boat 30 shown in FIG. 1 and the physical vapor deposition apparatus 40 shown in FIG. Note that Alq _{3 as} a host light emitting material and me-DC as a guest light emitting material were used.
The host light emitting material and the guest light emitting material were housed in the heating boat 30 so that M2 was not mixed and the host light emitting material was in contact with the guest light emitting material (see FIG. 3).
Alq ₃ and me-DCM2 stored in heating boat 30
Was 6/1. Then, the light emitting layer 20 having a total film thickness of about 50 nm was formed under the same conditions as in [Step-120] of Example 1.

If the temperature of the heating boat 30 is gradually increased by such an operation, first, the me, whose sublimation temperature is low,
-DCM2 mainly sublimates and is a guest light emitting material
Layered region mainly composed of e-DCM2 (first layered region)
21 are formed. At the interface with the hole transport layer 14, the layered region 21 mainly composed of the guest light emitting material mainly contains me-DCM 2, and as the distance from the interface with the hole transport layer 14 increases, Me-DCM
2, but the proportion of me-DCM2 is still high. Note that partial decomposition of me-DCM2 is effectively suppressed.

Thereafter, Alq ₃ having a high sublimation temperature also begins to sublime, and a layered region (second layered region) 22 containing Alq _{3 as} a host light emitting material and me-DCM2 as a guest light emitting material is formed. When the temperature of the heating boat 30 is further gradually increased, a layered region (third layered region) mainly composed of Alq ₃ as a host light emitting material is finally obtained.
23 are formed. This layered region 23 has an electron transporting property.

Alternatively, [Step-120] of Example 1
In the same manner as described above, FIG.
An optical element having a double hetero structure as shown in FIG.

[Step-230] Then, in the same manner as in [Step-130] of Example 1, the cathode 16 made of aluminum having a thickness of about 0.2 μm was formed on the light emitting layer 20 by vacuum evaporation. .

When the characteristics of the organic electroluminescent device 10 as an optical device that emits red light were measured, the maximum emission wavelength was 645 n at an applied voltage of 9 volts.
m. The measurement results of the emission spectrum are shown in FIG. In addition, the shape of the spectrum revealed that me-DCM2 was the emission center. Applied voltage 1
At 3 volts, a luminance of about 200 cd / m ² could be obtained. In this optical element 10, the hole transport layer 14 made of TPD is obtained from the measurement result of the spectrum.
It was revealed that the light emitting layer 20 in which me-DCM2 was specifically doped into Alq ₃ was formed near the interface between the light emitting layer 20 and the light emitting layer 20. In addition, a value of (0.69, 0.31) was shown on the CIE chromaticity coordinates.

Comparative Example 1 In Comparative Example 1, the same host luminescent material (Alq ₃ ) and guest luminescent material (me-DCM2) as in Example 2 were used. Comparative Example 1 is different from Example 2 in that Alq is separately stored in two light emitting material storage containers.
₃ and me-DCM2. In the same step as [Step-220] in Example 2, the film-forming speed of Alq _{3 as} the host light emitting material was 0.2 to 0.4 nm.
After adjusting the film formation rate of me-DCM2, which is a guest light emitting material, to about 0.1 nm / second, the shutter 44 was opened to form a light emitting layer having a thickness of about 50 nm. At this time, the film thickness ratio was calculated using the value of a quartz oscillator monitor as Alq ₃
/ Me-DCM2 = 100/2.
Except for these points, the method for manufacturing the optical element in Comparative Example 1 was the same as the method for manufacturing the optical element described in Example 2.

After the fabrication of the optical element, the depression 31A of the heating boat 30 containing the me-DCM2 was observed, and carbonization due to decomposition of the me-DCM2 was observed. In addition, the characteristics of the manufactured optical elements vary greatly,
In the method of Comparative Example 1, an optical element that emits red light with stable characteristics using me-DCM2 as a guest light emitting material could not be manufactured.

Comparative Example 2 In Comparative Example 2, the same host luminescent material (Alq ₃ ) and guest luminescent material (DCM2) as in Example 1 were used. Comparative Example 2 is different from Example 1 in that Alq ₃ and DCM2 were mixed in a mortar in a weight ratio of 6/1.
And then housed in a single light-emitting material storage container. Except for this point, the method for manufacturing the optical element in Comparative Example 2 was the same as the method for manufacturing the optical element described in Example 1.

The light emitting layer of the optical element thus manufactured is not in a uniform amorphous state, and the obtained optical element has various adverse effects such as no light emission or low luminance even when light is emitted. I was AFM (Atomic Force M
When the surface state of the light emitting layer was observed with an icroscope),
It was suggested that many irregularities were present on the surface of the light emitting layer, and as a result, a light emitting layer with severe irregularities was formed.

Example 3 Example 3 relates to a method for manufacturing an optical element according to the second aspect of the present invention. FIG. 7A is a schematic cross-sectional view of an organic electroluminescent device, which is an optical device according to the third embodiment. This optical element 50 has a structure in which an organic material layer 53 including a light emitting layer 60 is sandwiched between an anode 52 and a cathode 56. And the light emitting layer 60
It has a layered region 62 containing a host light emitting material and a guest light emitting material having an emission wavelength different from the emission wavelength of the host light emitting material. Also, the host luminescent material is
It has a lower vaporization temperature than the guest light emitting material and has a hole transporting property. Note that the optical element in Example 3 has a single hetero structure in which the organic material layer 53 is stacked from the anode 12 side with the light emitting layer 60 also serving as the electron transport layer and the electron transport layer 55.

In Example 3, α-naphthylpheninediamine (α) was used as the host luminescent material constituting the luminescent layer.
-NPD) was used. In addition, rubrene (Rub), which is generally used as a laser dye as a guest light emitting material,
ene) was used. The light emitting layer 60 includes, from the anode side to the cathode side of the light emitting layer 60, a layered region (first layered region) 61 containing a host light emitting material as a main component, and a layered region containing a host light emitting material and a guest light emitting material. A region (second layered region) 62 and a layered region (third layered region) 63 containing a guest light emitting material as a main component are sequentially formed by physical vapor deposition. The structural formula of rubrene is shown in the following formula (5).

[0072]

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Further, the anode 12 is composed of a transparent electrode made of an ITO film, and the cathode 16 is composed of a metal electrode (aluminum electrode). In Example 3, to form an electron transporting layer 55 from the Alq _3.

Also in the third embodiment, such an optical element is manufactured by using a physical vapor deposition apparatus provided with a luminous material storage container (a vacuum deposition apparatus in the third embodiment).
At this time, the host light emitting material and the guest light emitting material are stored in the light emitting material storage container so that the host light emitting material and the guest light emitting material are not mixed and the host light emitting material is in contact with the guest light emitting material (FIG. 3), the luminescent material storage container is heated to form a layered region 6 of the luminescent layer 60.
1, 62 and 63 are formed by a physical vapor deposition method (the vacuum deposition method also in the third embodiment).

Hereinafter, the physical vapor deposition apparatus 40 and the heating boat 3 corresponding to the light emitting material storage container shown in FIGS.
A method of manufacturing the optical element of Example 3 using 0 will be described.

[Step-300] In Example 3, a prototype substrate having the same structure as in Example 1 was produced.

[Step-310] Next, a transparent substrate 51 made of glass is placed on the stage of the physical vapor deposition apparatus 40 shown in FIG.
And using the heating boat 30 shown in FIGS. 2 and 3,
The light emitting layer 60 was formed by a physical vapor deposition method (specifically, a vacuum deposition method). In addition, α-NP which is a host luminescent material
The host light-emitting material and the guest light-emitting material were stored in the heating boat 30 so that D and rubrene as the guest light-emitting material were not mixed and the host light-emitting material was in contact with the guest light-emitting material (see FIG. 3). The weight ratio between α-NPD and rubrene stored in the heating boat 30 was 8/1.
Then, the heating boat 30 is heated, the shutter 44 is opened, the heating boat 30 is continuously heated, and the temperature of the heating boat 30 is gradually increased, so that the light emitting layer 60 having a total film thickness of about 50 nm is formed.
Was formed. The film formation rate was 0.2 to 0.4 nm / sec.

When the temperature of the heating boat 30 is gradually increased by such an operation, first, the host light-emitting material having a low sublimation temperature mainly sublimates, and the layered region (the first light-emitting material) composed mainly of the host light-emitting material A layered region) 61 is formed.
The layered region 61 mainly composed of the host luminescent material is
At the interface with 2, most consist of α-NPD as a component,
As the distance from the interface with the anode 52 increases, the proportion of α-NPD in the components of the layered region 61 decreases, but the proportion of α-NPD is still high. This layered region 61 has a hole transporting property.

Thereafter, the guest light emitting material having a high sublimation temperature also begins to sublime, and a layered region (second layered region) 62 containing α-NPD as the host light emitting material and rubrene as the guest light emitting material is formed. Further, when the temperature of the heating boat 30 is gradually increased, a layered region (third layered region) 63 mainly composed of rubrene as a guest light emitting material is finally formed.

Through these steps, the content of the guest light emitting material in the light emitting layer 60 is reduced.
In other words, it is possible to gradually increase the content of the guest light emitting material in the light emitting layer 60 from the anode side to the cathode side of the light emitting layer 60, or Further, the light emitting layer 60 can have a structure having a desired guest light emitting material content in the thickness direction. In addition, by changing the weight ratio between the host light emitting material and the guest light emitting material stored in the heating boat 30, the amount of the guest light emitting material doped into the host light emitting material can be controlled. Therefore, it is possible to produce optical elements having various light emitting layer structures, and as a result, optical elements having various light emitting wavelengths can be obtained, so that a desired light emitting wavelength can be obtained from a wide range of light emitting wavelength regions. .

In the above-described process, if the shutter 44 is closed after the formation of the second layered region, the formation of the layered region (third layered region) 63 containing rubrene, which is a guest light emitting material, as a main component is omitted. The optical element having the above structure can be manufactured. With such a structure, optical elements having different emission wavelengths can be manufactured.

As shown in a schematic cross-sectional view of FIG. 7B, the organic material layer 53 has a hole transport layer 54, a light emitting layer 60, and an electron transport layer 55 from the anode 52 side. Can be fabricated to form an optical element having a double heterostructure. In this case, before forming the light emitting layer 60, the hole transport layer 54 made of α-NPD may be formed by a vacuum evaporation method.

[Step-320] Subsequently, the electron transport layer 55 made of Alq ₃ having a thickness of about 50 nm is formed on the light emitting layer 60.
Was formed at a film formation rate of 0.1 to 0.2 nm / sec.
Although a heating boat containing Alq ₃ is disposed in the physical vapor deposition apparatus 40, illustration of such a heating boat is omitted.

[Step-330] Then, in the same manner as in [Step-130] of the first embodiment, a cathode 56 made of aluminum having a thickness of about 0.2 μm is formed on the electron transport layer 5 by vacuum evaporation.
5 was formed.

The characteristics of the organic electroluminescent device 50, which is an optical device that emits yellow light, was measured when the applied voltage was 10 volts, and the maximum emission wavelength was 560.
nm. Also, the shape of the spectrum revealed that rubrene was the emission center. At an applied voltage of 10 volts, a luminance of about 5000 cd / m ² could be obtained. In this optical element 50, from the measurement result of the spectrum, the light emitting layer 60 in which rubrene is specifically doped into α-NPD near the interface between the electron transport layer 55 made of Alq ₃ and the light emitting layer 60 is shown. It became clear that it was formed. In addition, a value of (0.45, 0.45) was shown on the CIE chromaticity coordinates.

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. The various conditions and the materials used described in the examples are merely examples, and can be changed as appropriate. In the embodiment, the description has been made by taking an optical element that emits red or yellow light as an example, but an optical element that emits other colors (G, B) is also similar to that described in the embodiment. It can be manufactured by a method, for example, a full-color or multi-color display device using an organic electroluminescent device can be manufactured, and the organic electroluminescent device can be used as a light source, and is applied to other optical uses. You can also.
Furthermore, the method of the present invention can be applied to the formation of a hole transport layer or an electron transport layer in some cases.

[0087]

As described above, according to the method for manufacturing an optical element of the present invention, it is possible to form a host-guest-based light-emitting layer made of an organic light-emitting material using a single light-emitting material storage container. Thus, an optical element having various element structures having excellent characteristics can be manufactured by an integrated vacuum process without significantly modifying a physical vapor deposition apparatus. In addition, even if the guest light emitting material is a material that partially decomposes during vaporization, the guest light emitting material can be surely vaporized. As a result, a host-guest-based light-emitting layer composed of an amorphous organic thin film composed of two types of light-emitting materials can be reliably formed by a physical vapor deposition method, and stable and excellent light emission is obtained. An optical element having characteristics, for example, an organic electroluminescent element can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view of a physical vapor deposition apparatus which is a vacuum evaporation apparatus.

FIG. 2 is a schematic cross-sectional view and an exploded perspective view of a heating boat corresponding to a light-emitting material storage container.

FIG. 3 is a schematic sectional view and a perspective view of a heating boat in which a host light emitting material and a guest light emitting material are stored.

FIG. 4 is a schematic cross-sectional view of an organic electroluminescent device having a single heterostructure, which is an optical device in Example 1.

FIG. 5 is a schematic cross-sectional view of an organic electroluminescent device having a double hetero structure, which is an optical device in Example 1.

FIG. 6 is a graph showing a measurement result of an emission spectrum of an optical element in Example 2.

FIG. 7 is a schematic cross-sectional view of an organic electroluminescent element which is an optical element in Example 3.

FIG. 8 is a schematic sectional view of an example of a conventional organic electroluminescent device.

FIG. 9 is a diagram schematically showing a specific example of an organic electroluminescent device.

[Explanation of symbols]

10, 10A, 50, 50A ... optical element, 11,
51: transparent substrate, 12, 52: anode, 13, 5
3 ... organic material layer, 14, 54 ... hole transport layer, 1
5, 55: electron transport layer, 16, 56: cathode, 2
0,60 ... light-emitting layer, 21, 22, 23, 61, 6
2, 63 ... layered area, 30 ... heating boat, 31
... body, 31A ... recess, 32 ... lid, 33
..Apertures, 40... Physical vapor deposition apparatus, 41,4
2 ... Support arm, 43 ... Evaporation mask, 44
..Shutter, 45 ... Shutter spindle

Claims (11)

[Claims] An organic material layer including a light-emitting layer has a structure sandwiched between an anode and a cathode, and the light-emitting layer has a host light-emitting material and an emission wavelength of the host light-emitting material. Having a layered region containing a guest light-emitting material having a different emission wavelength, the host light-emitting material has a higher vaporization temperature than the guest light-emitting material, and at least one of an electron-transport property and a hole-transport property. A method for manufacturing an optical element having an electron-transporting property using a physical vapor deposition apparatus provided with a light-emitting material storage container, so that a host light-emitting material and a guest light-emitting material are not mixed.
In addition, after storing the host light emitting material and the guest light emitting material in the light emitting material storage container so that the host light emitting material is in contact with the guest light emitting material, the layered region of the light emitting layer is heated by heating the light emitting material storage container. Is formed by a physical vapor deposition method. 2. The method for manufacturing an optical element according to claim 1, wherein the content of the guest light emitting material in the light emitting layer is gradually reduced from the anode side to the cathode side of the light emitting layer. 3. A layered region containing a guest light emitting material as a main component, the layered region containing a host light emitting material and a guest light emitting material, and a host light emitting material as a main component, from the anode side to the cathode side of the light emitting layer. 2. The method for manufacturing an optical element according to claim 1, wherein the layered regions to be formed are sequentially formed by a physical vapor deposition method. 4. An organic material layer including a light-emitting layer has a structure sandwiched between an anode and a cathode, and the light-emitting layer has a host light-emitting material and an emission wavelength of the host light-emitting material. Having a layered region containing a guest light emitting material having a different emission wavelength, the host light emitting material has a lower vaporization temperature than the guest light emitting material, and has at least a hole of electron transporting property and hole transporting property. A method for manufacturing an optical element having transportability using a physical vapor deposition apparatus provided with a light-emitting material storage container, so that a host light-emitting material and a guest light-emitting material are not mixed.
In addition, after storing the host light emitting material and the guest light emitting material in the light emitting material storage container so that the host light emitting material is in contact with the guest light emitting material, the layered region of the light emitting layer is heated by heating the light emitting material storage container. Is formed by a physical vapor deposition method. 5. The method for manufacturing an optical element according to claim 4, wherein the content of the guest light emitting material in the light emitting layer is gradually increased from the anode side to the cathode side of the light emitting layer. 6. A layered region containing a host luminescent material as a main component, the layered region containing a host luminescent material and a guest luminescent material, and a guest luminescent material as a main component, from the anode side to the cathode side of the light emitting layer. The method for manufacturing an optical element according to claim 4, wherein the layered regions to be formed are sequentially formed by a physical vapor deposition method. 7. The method for manufacturing an optical element according to claim 1, wherein the light emitting layer has a desired guest light emitting material content in a thickness direction thereof. 8. The anode is composed of a transparent electrode, the cathode is composed of a metal electrode, and the organic material layer is formed by laminating a hole transport layer and a light emitting layer also serving as an electron transport layer from the anode side. The method for manufacturing an optical element according to claim 1, wherein the method comprises: 9. The anode comprises a transparent electrode, the cathode comprises a metal electrode, and the organic material layer comprises, from the anode side, a hole transport layer, a light emitting layer,
The method for manufacturing an optical element according to claim 1, wherein the optical element is formed by laminating an electron transport layer. 10. The anode comprises a transparent electrode; the cathode comprises a metal electrode; and the organic material layer comprises, from the anode side, a light emitting layer also serving as a hole transport layer and an electron transport layer laminated. The method for manufacturing an optical element according to claim 4, wherein the method comprises: 11. The anode comprises a transparent electrode, the cathode comprises a metal electrode, and the organic material layer comprises, from the anode side, a hole transport layer, a light emitting layer,
The method for manufacturing an optical element according to any one of claims 4 to 6, wherein the method is formed by laminating an electron transport layer.