JP6844621B2 - Coating liquid, its manufacturing method, ink for manufacturing electronic devices, electronic devices, organic electroluminescence elements, and photoelectric conversion elements - Google Patents

Description

The present invention relates to a coating liquid, a manufacturing method thereof, an ink for manufacturing an electronic device, an electronic device, an organic electroluminescence element, and a photoelectric conversion element, and in particular, efficiently removes water and oxygen adhering to an organic material, and is good. The present invention relates to a coating liquid capable of producing an electronic device having excellent performance, a method for producing the same, an ink for producing the electronic device, an electronic device, an organic electroluminescence element, and a photoelectric conversion element.

1 Spread of Organic Electronic Devices and Current Issues Electronic devices using organic compounds, for example, the methods described in organic electronics Japanese Patent Application Laid-Open No. 2010-272619, Japanese Patent Application Laid-Open No. 2014-077422, etc. are used. Various electronic devices such as compounds (also referred to as "OLEDs" and "organic EL elements"), organic photoelectric conversion elements, and organic transistors have been developed, and with their technological progress, various industries have been developed.・ It is becoming more widespread in the market field.
For example, organic EL elements, which are typical examples of organic electronic devices, have begun to be used in various fields such as displays, lighting, and indicators, and have already entered the present life together with liquid crystal displays and light emitting diodes (LEDs). , We are about to enter a period of dramatic spread and expansion.
However, in order to promote the development of organic electronic devices such as organic EL devices, many problems that must be solved in the research and development process remain. In particular, various problems derived from the use of organic compounds remain as problems common to or peculiar to various organic electronic devices. It can be said that these problems to be solved are the ultimate problems that are directly linked to further improvement of performance such as quantum efficiency and light emission lifetime, and further improvement of productivity, that is, cost reduction.

Regarding the performance issues among the above ultimate issues, in electronic displays, organic EL elements are already used in the main display of smartphones, and large displays larger than 50 inches are on the market as products. In terms of lighting and signage, the white element has achieved a luminous efficiency of 139 Lm / W, which is about twice that of a fluorescent lamp, and the red phosphorescent element and green phosphorescent element have a half-brightness life of 100. A long life of 10,000 hours has been achieved, and even the most difficult blue phosphorescent element has achieved a result of exceeding 100,000 hours. It seems that it has already reached a level sufficient for practical use.

On the other hand, regarding the issue of productivity, that is, cost, as will be described in detail later, the RGB side-by-side display, which is an advantage of the original organic EL element, has not reached mass production in a large display. The manufacturing method by the coating method, which has been developed for the purpose of reducing the production load, still has a lot of room for improvement in the purification and handling of solvents and organic materials.
That is, it can be said that solving the low productivity is a necessary condition for developing the organic EL element. It is also considered that this is the same for other organic electronic devices, for example, organic photoelectric conversion elements.
Therefore, in the following, problems of the prior art related to the manufacture of an organic EL element, which is a typical example of an organic electronic device, will be described, particularly from the viewpoint of the ultimate problem relating to productivity.

2 Problems concerning the organic functional layer forming method First, the method of forming the organic functional layer, that is, the vacuum vapor deposition method (also referred to as "vacuum thin film deposition method") and the wet coating method ("wet coating method", "wet coating method" The problems caused by the film formation method) will be described.

2.1 Effects of Moisture and Oxygen on Organic Functional Layers Organic EL devices have electrons and holes in the light emitting material (generally also referred to as "dopant") existing in the light emitting layer, which is one of the organic functional layers. The basic principle is that the exciter formed when is injected and its recombination occurs emits light when it returns to the basal state.
As the name implies, this exciter is a very active chemical species that is in an excited state, so it easily reacts with water molecules and oxygen molecules, and easily undergoes chemical changes such as decomposition and modification or state changes, and is luminescent. Will decrease. That is, it is one of the factors that reduce the light emission life.
That is, when forming an organic functional layer such as a light emitting layer, it is necessary to perform it in an environment where no water or oxygen enters in the forming process.

On the other hand, in the organic EL element, unlike the LED, the existence state of the organic compound constituting the light emitting layer is not a crystal but an amorphous (amorphous), which is a condition for high efficiency light emission. Therefore, in order to form a homogeneous amorphous film, it is desired that the molecular state (amorphous state) of the organic compound during the film formation and the surrounding environment are constant.
Therefore, for the reasons such as the prevention of harmful effects due to moisture and oxygen and the need to make the organic compound amorphous, the film forming method for the organic functional layer of the organic EL element exhibiting good performance so far is the vacuum deposition method. It was due to. Both the organic EL displays for smartphones that have already been mass-produced and the organic EL displays used for large-sized TVs employ a thin-film deposition method as a film forming method for organic functional layers.

2.2 Problems of forming an organic functional layer by the vacuum vapor deposition method However, when an organic EL element is manufactured by the vacuum vapor deposition method, there are the following problems related to the emission color reproduction method.
Organic electroluminescence is self-luminous, and the emission color is uniquely determined by the light-emitting material that constitutes the light-emitting layer. Therefore, it is basically red (Red: R), green (Green: G), and blue (Blue: B). A method (RGB side-by-side method) has been adopted in which an organic EL element of each emission color is produced for each pixel and the organic EL elements are arrayed to form a display.

In the case of the RGB side-by-re-method, it is necessary to form a different light emitting layer for each pixel of RGB, and in order to do this in a large area, each pixel is formed while shifting the shadow mask for each pixel. The method is common. At this time, since the method of forming (depositing) the light emitting layer or the like is a vacuum vapor deposition method, there is a decisive problem that the shadow mask thermally expands due to the radiant heat from the vapor deposition source, causing pixel misalignment.
Due to this crucial issue, small to medium sized displays for smartphones are produced in hundreds of millions of panels annually on an RGB side-by-side basis, but on large displays larger than 50 inches. , The production yield is low due to the thermal deformation of the shadow mask, and large-scale production is not carried out.

On the other hand, as another method for reproducing full color, a method (color filter method) is adopted in which white light obtained from an organic EL element is color-divided into RGB by passing through a color filter to reproduce full color. Large-scale displays that have already been mass-produced are an array of organic EL elements that emit white light for each pixel, and the color filter method can obtain high-contrast light emission with independent pixels. There is a problem that the advantages and features cannot be fully exhibited.

2.3 Possibility of forming an organic functional layer by a wet coating method The organic functional layer constituting the organic EL element has a laminated structure of about 4 to 7 layers, and the total layer (film) thickness is about 100 to 200 nm. is there. If it is too thin, the anode and cathode will be partially short-circuited due to the influence of the surface roughness of the electrode that is the base layer, and a current leak phenomenon will occur.
If it is thicker than this, the charge conduction mechanism of the organic EL element is different from Ohm's law, and the space charge limited current (SCLC) is based on the child's law. Therefore, the current density flowing is the distance between the electrodes. Since it is inversely proportional to the cube of the above, there arises a problem that the drive voltage rises significantly and the power consumption increases.

The organic functional layer of an organic EL element is generally deposited with a low molecular weight compound, but instead of the low molecular weight compound, a π-conjugated polymer such as polyphenylene vinylene or polyfluorene is used for carrier transfer and light emission. There is also a method of using a light emitting polymer (LEP) which is utilized for both of the above. Since the polymer material cannot be vapor-deposited, the organic functional layer is produced by a wet coating method (wet film forming method, wet coating method) such as spin coating, die coating, flexographic printing, and inkjet printing.
Further, even if it is a low molecular weight compound that can be vapor-deposited, it is possible to form a smooth coating film on the nanometer order by appropriately selecting the molecular structure of the compound and the solvent to be dissolved. Minolta has announced a prototype of a phosphorescent white element that emits light with high efficiency by laminating and coating four layers of low molecular weight compounds.

At present, companies and research institutes all over the world are actively conducting research and development to manufacture organic EL devices by this method, that is, a wet coating method (wet coating method) for low molecular weight materials (for example, patents). See Reference 1.).
However, as will be described in detail later, in the purification and handling of solvents and organic materials (solutes), problems caused by easily soluble water and oxygen contained in the coating liquid have not been sufficiently solved.

Japanese Patent No. 4389494

The present invention has been made in view of the above problems and situations, and the problem to be solved is that it is possible to efficiently remove water, oxygen, etc. adhering to an organic material, and to manufacture an electronic device having good performance. It is an object of the present invention to provide a coating liquid, a method for producing the same, an ink for manufacturing an electronic device, an electronic device, an organic electroluminescence element, and a photoelectric conversion element.

In order to solve the above problems, the present inventor is a coating liquid containing an organic compound and an organic solvent in the process of examining the cause of the above problems, and the above-mentioned organic under the conditions of 50 ° C. or lower and atmospheric pressure. The present invention has been found to be able to provide a coating liquid capable of efficiently removing water, oxygen and the like, and a method for producing the same, when the concentration of dissolved carbon dioxide with respect to the solvent is within a specific range. Further, by using this coating liquid, it is possible to provide an ink for manufacturing an electronic device, an electronic device, an organic electroluminescence element, and a photoelectric conversion element having good performance.
That is, the above-mentioned problem according to the present invention is solved by the following means.
In order to facilitate the understanding of the present invention, the basic policy and the background of research and development according to the present invention will be described later.

1. 1. A method for producing a coating liquid containing an organic compound and an organic solvent.
In the coating liquid, the dissolved carbon dioxide concentration with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is within the range of 1 ppm or more and the saturation concentration with respect to the organic solvent.
The step of mixing the organic compound and carbon dioxide,
Using supercritical fluids, have a step of separating a substance in a solution containing an organic compound,
A method for producing a coating liquid, wherein the dissolved carbon dioxide contains carbon dioxide derived from supercritical carbon dioxide.
2 . The method for producing a coating liquid according to item 1, wherein the coating liquid is a coating liquid for manufacturing an electronic device.
3 . The method for producing a coating liquid according to item 1 or 2 , wherein the coating liquid is an ink for an inkjet.
4 . A coating solution containing an organic compound and an organic solvent.
The concentration of dissolved carbon dioxide with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is within the range of 1 ppm or more and the saturation concentration with respect to the organic solvent, and the dissolved carbon dioxide is carbon dioxide derived from supercritical carbon dioxide. A coating liquid characterized by containing.

5 . The coating liquid according to item 4 , wherein the dissolved carbon dioxide concentration is in the range of 5 to 1000 ppm under the above conditions.

6 . The fourth item is characterized in that when oxygen is present in the coating liquid in an amount of 1 ppm or more, the dissolved carbon dioxide concentration is contained in the range of 1.0 to 100,000 times the dissolved oxygen concentration under the above conditions. Alternatively, the coating liquid according to item 5.

7 . The coating liquid according to any one of items 4 to 6 , wherein the coating liquid is a coating liquid for manufacturing an electronic device.

8 . The coating liquid according to Item 7 , wherein the electronic device is a light emitting device.

9 . The coating solution according to any one of items 4 to 8 , wherein the organic compound is an organic electroluminescence material.

10 . The coating liquid according to any one of items 4 to 9 , wherein the coating liquid is an ink for an inkjet.

11 . An ink for manufacturing an electronic device, which contains the coating liquid according to any one of items 4 to 10.

12 . An electronic device having an organic functional layer formed by using the coating liquid according to any one of items 4 to 10.

13 . An organic electroluminescence device having an organic functional layer formed by using the coating liquid according to any one of items 4 to 10.

14 . A photoelectric conversion element having an organic functional layer formed by using the coating liquid according to any one of items 4 to 10.

(Basic policy and history of research and development according to the present invention)
Based on the technical background described above or described later, it is presumed that the technology to be adopted in the method for manufacturing an organic EL device will inevitably be the following selection.
<Basic policy regarding manufacturing method>
(1) It is preferable to use a low molecular weight compound as the organic EL compound (a high molecular weight compound is not preferable).
(2) The coating method is used as the film forming method (the vapor deposition method is not preferable).
(3) The solvent in the coating liquid is preferably a general-purpose solvent (an expensive dehydrated high-purity solvent is not preferable).
(4) The dissolution is preferably in a monomolecular state (a microcrystal dispersion is not preferable).
(5) It is preferable to utilize the adsorption-desorption equilibrium for purification of the compound (thermal equilibrium is not preferable).
First of all, when the above basic policies are adopted, it is an immediate technical issue to create a method that satisfies all of the policies (3) to (5), and achieving them is the most valuable technology. I think that there is, and I have been researching and developing the means to achieve it.

As a result, in order to achieve the above-mentioned "(3) The solvent in the coating solution is preferably a general-purpose solvent", it is not enough to simply use a dehydrating or deoxidizing solvent, and a special gas in the solution is present. It was found that the fact that the gas is dissolved at a concentration close to saturation preferably increases the robustness against the acquired moisture and oxygen, and it is very simple, but that is the present invention. It turned out to be the essence of. The gas is carbon dioxide.

In a conventional coating film forming element, the coating solution is stored in a nitrogen atmosphere for a long time, and the dissolved oxygen and the nitrogen in the atmosphere are replaced by equilibrium, or oxygen is expelled by bubbling or pressurizing nitrogen gas, or it is used. The coating solution was deoxidized by using a similar method.
However, in the coating process, if the coating solution is exposed to the atmosphere even for a moment, the coating solution immediately absorbs oxygen and water, and the dehydration / deoxidization coating solution prepared with the utmost care is ruined, resulting in organic EL. It causes a great deterioration in the characteristics of the element, especially the light emission life.
The phenomenon we discovered is that water and oxygen are removed in the initial state of the coating solution, but by dissolving carbon dioxide close to the saturated concentration in the solution, the solution itself becomes difficult to absorb water and oxygen. That is.

We will briefly introduce how we made this invention.
As mentioned earlier, in the development of coating and depositing low molecular weight compounds, we have found a technique for purifying organic EL materials by supercritical high performance liquid chromatography (HPLC) of carbon dioxide (patented). No. 4389494).
However, it has been found that the performance fluctuates greatly every time the element is manufactured due to contact with air in the film forming process or contamination with a small amount of water adhering to the coating device.

As a result of diligent studies to solve the problem, the present inventors completely take the dissolved oxygen out of the solution system when the supercritical carbon dioxide escapes from the solution as gaseous carbon dioxide. In addition, water contained in a small amount is also released by hydrogen bonding with carbon dioxide, and carbon dioxide remaining at a concentration close to saturation prevents oxygen and water from being mixed into the solution system. We found that when we applied the eluent purified from supercritical HPLC as it was, we found that it was possible to manufacture stable and good devices with high performance and almost no variation in performance. It led to the invention.
Further, it has been found that the same effect is exhibited not only by supercritical carbon dioxide but also by bubbling or contacting carbon dioxide gas with an organic solvent solution of an normally dissolved organic EL material.

To summarize the description so far, the present invention is composed of the following technical elements.
In addition, the description so far has been about organic EL devices by the coating film formation method using low molecular weight compounds, but this is only one of the typical and most effective applications, and low molecular weight compounds. Needless to say, the same technique can be applied to other electronic devices for forming a film by applying the above, for example, an organic thin film solar cell, an organic transistor, an electrode using an organic compound, and the like.
(A) Coating solution containing carbon dioxide at a concentration close to saturation in a solution in which a low molecular weight compound is dissolved (b) Coating solution in which carbon dioxide is brought into contact with the solution in a supercritical state (c) Solute The above (a) to (c) are simultaneously achieved by using a solution for coating dispersed in a solvent through an adsorption-desorption equilibrium, that is, an eluent purified by supercritical carbon dioxide HPLC without completely concentrating and drying. However, the present invention is not a premise, and if it is dissolved in carbon dioxide and is dispersed (that is, completely dissolved) in a solvent through an adsorption-desorption equilibrium, any method can be used. There is no such thing.

By the above means of the present invention, a coating liquid capable of efficiently removing water, oxygen, etc. adhering to an organic material to produce an electronic device having good performance, a manufacturing method thereof, an ink for manufacturing an electronic device, and an electronic device. , An organic electroluminescence element and an organic photoelectric conversion element can be provided.
Although the mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.
The coating solution of the present invention is contained in the solution before and after coating because the dissolved carbon dioxide concentration with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is within the range of 1 ppm or more and the saturation concentration with respect to the organic solvent. When the dissolved carbon dioxide escapes as gaseous carbon dioxide, it takes the dissolved oxygen out of the solution system together, and the water contained in the solution in a small amount is also carbon dioxide. It is removed by the hydrogen bond of. Furthermore, carbon dioxide remaining at a concentration close to saturation can prevent oxygen and water from being mixed into the solution system. As a result, a high-performance electronic device can be manufactured and the yield can be improved. The carbon dioxide in the present invention is dissolved in the coating liquid for the purpose of removing oxygen and water in the coating liquid and preventing oxygen and water from being mixed into the coating liquid, for example, for spraying. It is not used as a medium.

Comparison of thin-film deposition film and coating film: Results of particle size distribution analysis of organic compound fine particles in the film Comparison of thin-film deposition film and improved coating film: Results of particle size distribution analysis of organic compound fine particles in the film Schematic diagram of an apparatus using a packed column in supercritical fluid chromatography Schematic diagram showing an example of a display device composed of an organic EL element Schematic diagram of display unit A Schematic diagram showing a pixel circuit Schematic diagram of a passive matrix full-color display device Sectional drawing which shows the solar cell which consists of a bulk heterojunction type organic photoelectric conversion element Cross-sectional view showing a solar cell including an organic photoelectric conversion element provided with a tandem type bulk heterojunction layer. Schematic configuration of an organic EL full-color display device Schematic configuration of an organic EL full-color display device Schematic configuration of an organic EL full-color display device Schematic configuration of an organic EL full-color display device Schematic configuration of an organic EL full-color display device

The coating liquid of the present invention is a coating liquid containing an organic compound and an organic solvent, and the dissolved carbon dioxide concentration with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is 1 ppm or more and the saturation concentration with respect to the organic solvent. It is characterized by being within the following range. This feature is a technical feature common to or corresponding to the invention according to each claim.

In an embodiment of the present invention, the dissolved carbon dioxide concentration is preferably in the range of 5 to 1000 ppm under the above conditions from the viewpoint of exhibiting the effect of the present invention.

When oxygen is present in the coating liquid in an amount of 1 ppm or more, the dissolved carbon dioxide concentration is contained in the range of 1.0 to 100,000 times the dissolved oxygen concentration under the above conditions by using the coating liquid. It is preferable in terms of the stability of the created device.
It is preferable that the coating liquid is a coating liquid for manufacturing an electronic device in that an electronic device having good performance can be manufactured, and it is preferable that the electronic device is a light emitting device.

It is preferable that the organic compound is an organic electroluminescence material in terms of light emitting device life and luminous efficiency.

It is preferable that the coating liquid is an ink for an inkjet from the viewpoint of producing various devices.

The method for producing a coating liquid of the present invention is characterized by having a step of mixing the organic compound and carbon dioxide.
After the step of mixing the organic compound and carbon dioxide, it is preferable to produce the coating liquid using a solution containing the organic compound. That is, it is preferable in that carbon dioxide contained in the coating liquid can prevent the carbon dioxide from coming into contact with air in the film forming process and contaminating a small amount of water adhering to the coating apparatus into the coating liquid. Further, it is not necessary to carry out a step of preparing a coating liquid by re-dissolving the purified organic compound in a solvent suitable for coating film formation after concentrating and drying.
It is preferable to have a step of separating the substance in the solution containing the organic compound using a supercritical fluid from the viewpoint of improving the efficiency of the purification step.

The coating liquid of the present invention is suitably contained in an ink for manufacturing an electronic device.
The coating liquid of the present invention is suitably used for forming each organic functional layer of an electronic device, an organic electroluminescence element, and a photoelectric conversion element.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present application, "~" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value. Further, in the present invention, "ppm" indicates "mass ppm".

(Overview of the coating liquid of the present invention)
The coating liquid of the present invention is a coating liquid containing an organic compound and an organic solvent, and the dissolved carbon dioxide concentration with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is 1 ppm or more and the saturation concentration with respect to the organic solvent. It is characterized by being within the following range.
As described above, the present invention has been studied and completed based on the following basic policies (1) to (5).
(1) The organic EL compound is preferably a low molecular weight compound (a high molecular weight compound is not preferable).
(2) The coating method is used as the film forming method (the vapor deposition method is not preferable).
(3) The solvent in the coating liquid is preferably a general-purpose solvent (an expensive dehydrated high-purity solvent is not preferable).
(4) The dissolution is preferably in a monomolecular state (a microcrystal dispersion is not preferable).
(5) It is preferable to utilize the adsorption-desorption equilibrium for purification of the compound (thermal equilibrium is not preferable).
Hereinafter, the present invention will be described first from the viewpoint of the basic idea underlying each of the above policies, and then specific techniques will be described.

1. 1. Superiority of low molecular weight compounds over high molecular weight compounds The superiority of low molecular weight compounds over high molecular weight compounds in the formation of organic functional layers by the wet coating method will be explained.
(First factor): Superiority of purity Comparing low molecular weight compounds with high molecular weight compounds (so-called polymers), the difference can be clearly seen. First, it is preferable to apply sublimation purification to a low molecular weight compound because it has a small molecular weight, and recrystallization also has a small molecular weight distribution and is desirable. Further, as a method for purifying a low molecular weight compound, high performance liquid chromatography (HPLC) or column chromatography having low purification efficiency (low number of theoretical plates) can be used, which is preferable.
In most cases, high molecular weight compounds are purified by repeating a reprecipitation method using a good solvent and a poor solvent, and low molecular weight compounds are more likely to have high purity.
Further, when the polymer compound is a π-conjugated polymer compound, it is necessary to use a metal catalyst or a polymerization initiator for causing a polymerization reaction, and a substituent having a reaction activity remains at the polymerization terminal. This is also one of the reasons why low molecular weight compounds can be made more pure.

(Second factor) Advantage of molecular-specific energy level Light emitting polymer (LEP) is a π-conjugated polymer when the molecular weight increases. Therefore, a conjugated system is used to stabilize the molecule. In principle, the energy level difference between the excited state and the ground state of the singlet or triplet (also referred to as "energy level gap" or "band gap") becomes narrower. It becomes difficult to emit blue light. Further, in blue phosphorescence, which requires a higher energy level (large energy level difference) than the blue emission of fluorescence, it is structurally difficult for the luminescent polymer to form a transition metal complex as the luminescent substance. Furthermore, even attempts to use light-emitting polymer as the host, difficult to compounds with high triplet energy by expansion of said π-conjugated (abbreviated as "high T ₁ compound".).
In addition, there is no precedent for thermally activated delayed fluorescence (TADF), which has been attracting attention recently, with a π-conjugated polymer, and it is difficult to use it for high-efficiency blue light emission with high market demand.

On the other hand, in the case of low molecular weight compounds, it is not necessary to link the π-conjugated system, and aromatic compound residues to be the π-conjugated system unit are required, but they can be arbitrarily selected and they can be replaced at arbitrary positions. Therefore, for low molecular weight compounds, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and the triplet (T ₁ ) energy level can be intentionally adjusted. It is possible to make a blue phosphorescent substance, to host it, and to build a compound that causes the TADF phenomenon. The magnitude of extensibility at which an arbitrary electronic state or an arbitrary level can be intentionally designed and synthesized in this way is a factor of the second superiority of the low molecular weight compound.

(Third factor): Ease of compound synthesis Although the reason (factor) is similar to that of the second factor, the low molecular weight compound has no limitation on the molecular structure that can be synthesized as compared with the luminescent polymer (LEP), and in particular, it emits light. When the main chain is π-conjugated in a polymer, the applicable skeleton and synthetic method are limited, but in low-molecular-weight compounds, new functions are added and physical property values are adjusted (Tg, melting point, solubility, etc.) in the molecular structure. It is relatively easy to accomplish by, which is the third advantage of low molecular weight compounds.

2. Issues in the formation of an organic functional layer by a wet coating method using a low molecular weight compound What are the essential issues in the formation of an organic functional layer by a wet coating method using a low molecular weight compound?
In almost all materials used for organic EL devices, electrons and holes must move by hopping between molecules inside the organic EL device. Basically, electrons are hopping along the LUMO level, and holes are hopping using the HOMO level.
That is, if adjacent molecules do not exist so that the π-conjugated systems overlap each other, such carrier conduction does not occur. Therefore, it is advantageous to form a molecular structure with only the π-conjugated system units as much as possible.
For example, in order to improve the solubility in a solvent, if a plurality of sterically bulky substituents (sec-butyl group, tert-octyl group, triisopropylsilyl group, etc.) are substituted in one molecule. , The π-conjugated system between molecules becomes difficult to superimpose, and the hopping movement is hindered at the bulky substituent portion.

On the other hand, since the organic EL element constantly flows a current during light emission, the quantum efficiency is 100%, that is, the carrier recombination probability is 100% and the heat deactivation is 0%. Even if there is, the organic EL element needs to provide a potential difference between the anode and the cathode to create an electric current gradient in order to keep the carrier flowing, so the equivalent circuit of the organic EL element is a series connection of a diode and a resistor. Become.
That is, it is also known that Joule heat is generated inside the organic EL element during energized light emission, and that heat is actually generated at 100 ° C. or higher inside the element, particularly in the light emitting layer where recombination occurs.
Further, since the organic layer thickness of the entire organic EL element is an extremely thin layer of about 200 nm, heat is conducted between the layers (films), and the high temperature state is maintained not only in the light emitting layer but also in all the layers. Become.
When an organic molecule exposed to such a state exceeds its own glass transition point (Tg), it undergoes a phase transition from an amorphous state to a crystalline state.
This crystal gradually grows, and when it exceeds several tens of nm, it exceeds the layer thickness in which the compound existed, and the functional separation by the layer as an organic EL element becomes impossible, resulting in a decrease in luminous efficiency. Will be done.

Further, when this crystal exceeds the entire organic layer (100 to 200 nm) of the organic EL element, the anode and the cathode are short-circuited. Then, electric field concentration occurs in the short-circuited portion, and a large current flows in a minute region, so that the organic compound in that portion undergoes thermal decomposition, and a portion that does not emit light at all, a so-called dark spot, is formed.
That is, the low molecular weight compound of the organic EL device is a molecule that does not have a bulky non-aromatic substituent and has a glass transition point (Tg) of 100 ° C. or higher (preferably 150 ° C. or higher). Must be.
In order to construct such a molecule, the π-conjugated system is usually enlarged or the aromatic group is simply linked, but the compound that is usually produced has extremely low solubility in a solvent and is applied. Even if it cannot be a solution or can be applied, crystal precipitation and uneven distribution of substances will occur.

As a means to solve this dilemma, we have developed an epoch-making technology that can form a stable amorphous film and retain it even during energization (for example, Japanese Patent No. 5403179 and Japanese Patent Application Laid-Open No. 2014). -196258 Publication No.). Specifically, it has a bulky and highly flexible branched alkyl group, and only aromatic groups are linked to form a viaaryl structure, and many conformations are formed due to rotation obstacles generated around the CC bond axis. The number of components in the membrane by actively increasing or geometric isomers, or by allowing multiple molecules (for example, host and dopant) existing in the same layer to interact in various shapes and forms. Therefore, it is possible to increase the entropy in the thin film state and form a stable amorphous film.

In the production of an organic EL device by a wet coating method, the present inventors improved the molecular structure of a low molecular weight compound in accordance with the above-mentioned guidelines and optimized the drying conditions, etc., and found that the luminous efficiency was vapor deposition. A dramatic improvement was achieved, with 95% of the element and 90% of the luminous life. As a result, even devices that use phosphorescent dopants, especially blue phosphorescent dopants, which are considered to be the most difficult to improve the life of light-emitting dopants, have basic characteristics that are almost comparable to conventional vapor deposition deposition methods in the coating film formation method. I have found that I can demonstrate.
However, many problems still remain in the organic EL device whose performance has been improved in this way.
These issues include, for example, removal of the purity of the low molecular weight compound, the trace amount of water adhering to the surface of the compound, the oxygen content of the solvent used, the water content, and the like.

Further, for example, even if it is a low molecular weight compound generally used for coating, in order to exhibit the best performance, column chromatography and recrystallization are performed, then sublimation purification is performed, and an organic compound is further used. When it is stored, it is used by replacing it with a nitrogen atmosphere after passing through a vacuum state.
Even when an organic EL device manufactured by a coating method is manufactured under extremely strict control that eliminates such adverse effects as much as possible, it is difficult to exceed the performance of the organic EL device manufactured by a vapor deposition method. there were.
Furthermore, in the first place, the low productivity of the thin-film deposition method using vacuum adversely affects the increase in size and mass productivity of organic EL elements, that is, the cost, so the coating method is drawing attention. If the method is also carried out under such strict control, the productivity will be lower and the cost will be higher than the vapor deposition method.

3 Method for purifying compounds The advantage of low molecular weight compounds is that more purification means can be used than high molecular weight compounds and high purity can be achieved. However, after all, almost all of the organic compounds constituting the organic EL device generally used at present are used through a purification means called sublimation purification.
Sublimation purification is a classical purification method, but its purification efficiency (the number of theoretical stages) is overwhelmingly lower than that of purification methods such as recrystallization, column chromatography, and HPLC, and it effectively removes metals and inorganic substances. It is used as a means for removing solvents.
The main reason why sublimation purification is adopted in organic compounds for organic EL is that the manufacturing process of organic EL devices adopts the vacuum deposition method. If the organic compound contains even a very small amount of solvent, the solvent in the organic compound volatilizes when placed under vacuum in the vapor deposition apparatus, and the degree of vacuum is lowered.
That makes continuous production impossible and becomes a manufacturing problem. Therefore, a sublimation purification method is adopted in which the solvent is completely removed during purification.
Therefore, when the production method of the organic EL element is changed from the vapor deposition method to the coating method, the purification of the organic compound by the sublimation purification method is not indispensable for the above reason.

(Recrystallization)
Next, consider recrystallization, which is the most common method for purifying low-molecular-weight organic compounds.
This method is a purification method based on the second law of thermodynamics (Equation 1).
−ΔG = −ΔH + TΔS ・ ・ ・ (Equation 1)
As the distance between substances becomes shorter, the van der Waals force, hydrogen bond force, π-π interaction force, dipole-dipole interaction force, etc. increase, and the enthalpy (-ΔH) increases.
On the other hand, when the substance is completely dispersed in the medium, that is, when it is dissolved, the substance can move around freely, so that the disorder increases and the entropy (ΔS) increases.
In the second law of thermodynamics, all states of existence shift in the direction of keeping the free energy (-ΔG) of the cast constant or increasing it.

That is, the purification of the compound A to be purified by recrystallization can be reasonably explained by considering as follows.
When A is dissolved at a high temperature in a solvent called B which can dissolve A, A exists in a dispersed state. Therefore, the existence distance between A is large and it is difficult for them to interact with each other, so that the enthalpy (−ΔH) becomes extremely small.
On the other hand, A has an extremely large entropy (ΔS) because it can move around freely in the solution. When this high temperature solution is cooled, TΔS to which the absolute temperature T is applied becomes smaller than that before cooling. At that time, in order to keep the free energy (−ΔG) of the cast constant before and after cooling, the enthalpy (−ΔH) must be increased.
That is, as the temperature decreases and TΔS decreases, A must decrease the distance from A and increase the enthalpy. The extreme state is a crystalline state in which the distance between A and A is minimized, whereby the enthalpy term (−ΔH) increases.
As the enthalpy increases in this way, the number of components in the system decreases, so the entropy decreases, and by the amount of the decrease, crystals are formed and the enthalpy increases.

In this way, the entropy term (TΔS) decreases as the temperature decreases, and the enthalpy (−ΔH) increases due to crystallization to compensate for it, and the entropy term further increases due to the decrease in the number of components. Recrystallization is achieved by repeating the thermodynamic equilibrium in which the decrease in ΔS causes the size to decrease and crystallization occurs accordingly.
However, it should be noted that the interaction between the solute A and the solvent B. Since the solute A dissolves by being solvated with the solvent B, A does not dissolve in B in the first place unless the interaction between A and B is large. However, if the interaction is too large, the distance between A and A cannot be shortened enough to overcome the decrease in the entropy term that cools and decreases (because B intervenes between A and A). The result is that recrystallization does not occur.
That is, this purification method by recrystallization can be applied only when the interaction force of AA and the interaction force between AB can be adjusted to the conditions under which recrystallization occurs. In such a recrystallization purification method, since it is possible to purify a large amount of several hundred kg or more at a time, this method has been used for a long time in the chemical industry.

(Column chromatography)
Next, consider column chromatography (hereinafter, also referred to as "chromatography").
The most typical column chromatography is to use fine silica gel as the stationary phase, adsorb compound A on it, and gradually elute it with a mobile phase (B) called an eluent. ..
At this time, when the interaction (adsorption) between the silica gel surface and the compound A is antagonized by the interaction with the mobile phase (B), A is an adsorption-desorption equilibrium between the silica gel and the mobile phase B. When the interaction with silica gel is small, it elutes quickly, and when the interaction with silica gel is large, it elutes slowly.
At this time, the larger the number of round trips between adsorption and desorption equilibrium, the greater the number of theoretical plates (that is, purification efficiency). Therefore, the purification efficiency by the chromatographic method is proportional to the length of the stationary phase and also the passing speed of the mobile phase. It will be proportional and will also be proportional to the surface area of the stationary phase.
High performance liquid chromatography has made this possible, and it is a rare method that can realize a high number of theoretical plates backed by this theory, which is widely used for component analysis and quality assurance of organic compounds. It is due to the fact that.

The reason why this chromatographic method is superior to recrystallization is that the polarity of mobile phase B can be changed arbitrarily. For example, the mobile phase may be a mixed solvent of a good solvent and a poor solvent from the beginning, and the number of theoretical plates can be further increased by using a gradient method in which the ratio of good solvents is gradually increased during purification. ..
In addition, since the temperature can be changed arbitrarily, the range of application of the solute that can be purified is extremely wide, and the greatest feature is that it can be used as an almost general-purpose purification method.
On the other hand, there are also drawbacks of the chromatographic method. As mentioned above, the fundamental principle for increasing the number of theoretical plates is to utilize the adsorption-desorption equilibrium.

For example, when the chromatography method is performed using only the solvent B'(that is, a good solvent) that strongly interacts with the compound A in the mobile phase, the interaction between A and the mobile phase B'rather than the interaction between A and silica gel. If the action is strong, the number of round trips of the adsorption-desorption equilibrium is drastically reduced, and the purification effect is lowered.
That is, in order to enhance the purification effect, it is necessary to mix a large excess of the poor solvent C in addition to the good solvent B'to increase the number of round trips of the adsorption-desorption equilibrium. However, in this case, the purified and separated solution of compound A contains a large excess of C, and the biggest problem is that this must be concentrated.
For example, in order to obtain 1 g of A, the mixing ratio of the good solvent B'and the poor solvent C needs to be about 1:99 to 10:90, and generally about 10 L to 100 L of the poor solvent C is required. It will be necessary. Therefore, although HPLC preparative is applied to research and development, it is not used for mass production.

A means for solving the problem of poor solvent concentration is HPLC using supercritical carbon dioxide. Supercritical carbon dioxide is carbon dioxide converted into supercritical fluid at high temperature and high pressure, and other substances can be made into such supercritical fluid, but it is in a supercritical state at relatively low pressure and temperature. Since carbon dioxide can be realized, carbon dioxide is used exclusively for chromatography and extraction.
This supercritical carbon dioxide has characteristics different from ordinary fluids and liquids. That is, by changing the temperature and pressure, the polarity can be continuously changed according to the polarity of what is desired to be melted.

For example, this supercritical carbon dioxide is used when selectively extracting docosahexaenoic acid contained in fish heads, and the sebum is melted and adhered to the cleaning of special clothing using an adhesive. The agent achieves this by producing insoluble supercritical carbon dioxide under temperature and pressure control.
Although supercritical carbon dioxide can have various polarities in this way, the polarity of supercritical carbon dioxide formed at a relatively low temperature and pressure is about cyclohexane or heptane. In supercritical HPLC currently on the market, supercritical carbon dioxide of this degree of polarity is produced in the apparatus, mixed with a good solvent and entered into the column, and the compound is prepared by a mechanism similar to that of ordinary HPLC. Purification is performed.

In the HPLC system using supercritical carbon dioxide, it enters the detector after passing through the column, but usually the high temperature and high pressure state is maintained until that stage, and carbon dioxide also exists as a supercritical fluid. After that, carbon dioxide becomes a gas until it is separated at normal temperature and pressure, and at the time of separation, it escapes from the solution, so that concentration of a poor solvent becomes unnecessary. At this time, carbon dioxide can be recovered by a carbon dioxide recovery device equipped with a gas-liquid separation mechanism or the like described in References (Journal of the Society of Biotechnology, Vol. 88, No. 10, pp. 525-528, 2010). It can also be used as a supercritical fluid again.
Therefore, in the drug discovery industry, where it is necessary to synthesize a large number of new high-purity synthetic compounds, this supercritical HPLC has recently been actively utilized, and due to this effect, both for analysis and for preparative use. The selling price has dropped and it has become quite common.
From these characteristics and background, we have utilized this supercritical HPLC for the purification of organic EL materials that require high purity (Patent No. 4389494).
As described above, while improvement in productivity in the organic EL industry is desired, there are various purification methods for low molecular weight organic compounds, but each has advantages and disadvantages, the characteristics of the produced compound, and the required purity of the compound. , Appropriate purification methods are selected and used in combination depending on the availability of residual solvent.

4. Dissolution of Organic EL Compounds First, let us consider what dissolution is. Normally, the solute A is surrounded by the solvent molecule B by the interaction force between A and B, and the aggregate of A is separated and B is present around A, that is, A is made into an isolated single molecule state. That said, it's hard to tell if it really is.
For example, when A is a molecule having extremely low solubility or high crystallinity, if it is a crystal having a size equal to or larger than the wavelength of visible light, it can be easily detected by light scattering or the like that it is not dissolved. However, for example, in the case of a substance having low solubility halfway, even if the solvent molecule B surrounds the microcrystal consisting of several molecules of A, it seems to be dissolved. For organic EL devices, this can cause major problems later.

That is, in the thin-film deposition film formation, when forming thin layers (films) such as a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, the compounds constituting each layer are basically vapor-deposited. It lands on a substrate or an organic layer in the state of a vaporized isolated single molecule, which becomes a solid thin film and is formed into a film. Therefore, basically, a film is formed by a random aggregate of single molecules, and an ideal amorphous film is obtained.
On the other hand, in the case of the coating film formation method, if the coating solution is a dispersion of microcrystals of an organic EL compound, it looks like it is completely dissolved, but the actual condition of the obtained thin film is It becomes a thin film in which microcrystals are gathered together. Therefore, for example, the level of HOMO or LUMO is not that of a single molecule, but that of a stacked aggregate (crystal state), which may cause a decrease in performance.
In addition, over time, the microcrystals become nuclei and grow into coarse crystals, so it is not possible to separate the functions between the layers, and if it becomes a large crystal that short-circuits the anode and cathode, it becomes dark. There is a big problem of generating spots.
Regarding the coating film-forming device using low molecules, how to approximate the coating solution in the initial state to the single-molecule dispersion state based on the above-mentioned many years of study is first to obtain the same performance as the vapor deposition method. It is clear that it is a requirement.

Here, it was analyzed by small-angle X-ray scattering measurement (also referred to as "SAXS") how much molecular dispersion the coating liquid, which is usually intended to be strictly dissolved, is formed. Think based on the results.
In FIG. 1, the broken line is the particle size distribution curve (horizontal axis: particle size (nm), vertical axis: frequency distribution) of the fine particles of the compound constituting the thin film produced by the vapor deposition method, and the solid line is the thin film produced by the coating method. It is the particle size distribution of the fine particles of the constituent compound. Since both use the same compound, they can be compared directly.
The particle size distribution width of the fine particles of the compound in the vapor deposition film formation is such that the particle size at the position corresponding to the maximum peak is about 2 nm, which is close to monodisperse. This means that since the size of one or two molecules is one or two, in the vapor deposition film formation, substantially single molecules are randomly arranged to form an amorphous film.
On the other hand, in the particle size distribution of the fine particles of the compound in the coating film formation, the particle size at the position corresponding to the maximum peak is about 4.5 nm, which is wider than the particle size distribution in the vapor deposition film formation.
As mentioned earlier, since the same compound is used for vapor deposition and coating, the original crystallinity and cohesiveness of the compound are the same, and the difference is that the dispersed state of the molecules in the state of the coating solution is different. It is presumed that it was not a single isolated molecule but a dispersion of 5 to 10 microcrystals.
Of course, this coating solution is a so-called clear solution that does not precipitate crystals even when stored in a glove box under a nitrogen atmosphere for more than a week, but when analyzed by X-ray, it is a few molecule microcrystals. We misunderstand the dispersion of the above as a dissolved solution.

Next, FIG. 2 shows the results of examining the particle size distribution of the coating thin film prepared with the coating solution used in the prototype in which the compound was improved and the method for adjusting the coating liquid was improved by the same analysis.
As is clear from this result, in the result shown in FIG. 2, it can be seen that there is almost no difference in the particle size distribution of the fine particles of the organic compound between the vapor-deposited film and the coating film.
In this study, we confirmed that by improving the molecular structure and devising the dissolution method, it is possible to create a completely dissolved state in which almost isolated single molecules are dispersed.
This was a great achievement that proved that the organic EL element manufactured by the coating method can exhibit the same performance as the organic EL element produced by the vapor deposition method, but on the contrary, we found that the element by the coating method is equivalent to the element by the vapor deposition method. I also learned that there is a huge process load to do so.
In other words, in the current situation, in order to obtain the same performance as the vapor deposition method by the coating method, although it is a coating method that should be excellent in productivity, a very time-consuming process such as a dissolution method and a storage method is required. There is a high risk that this process will become a rate-determining process, especially when production increases, and improving this technology area is essential for future mass production. Is strongly recognized.

5. Purity of the solvent of the organic EL compound The organic EL element has a basic function of emitting light when the excited luminescent material returns to the ground state.
Further, it is necessary to transport electrons and holes from the electrode to the light emitting layer through a hopping phenomenon.
First, regarding the excited state, for example, in the case of an organic EL device doped with a light emitting material having a concentration of 5%, in order to continue emitting light at a brightness of ^{1000 cd / m 2 for one year, a simple calculation is performed.} One dopant needs to be an exciton about 1 billion times. At this time, if the exciton reacts with the water molecule even only once, it becomes a compound different from the original molecule. Further, when excitons react with oxygen molecules, some kind of oxidation reaction or oxidation coupling reaction occurs. This is the most typical phenomenon of chemical changes that cause functional deterioration of organic EL devices.

In addition, materials other than the luminescent material also enter the radical state almost the same number of times, and the radical anion state and the cation radical state are active species as compared with the ground state, which causes the functional deterioration of the organic EL device. Chemical changes may occur.
In other words, water molecules and oxygen molecules should not be present in the coating liquid at all, which is a prerequisite.
However, industrially, a high-purity anhydrous solvent is very expensive and difficult to handle. Therefore, in the end, in order to reduce the cost by the coating method, it is important how a general-purpose solvent can be used as a consumable.

6. Storage of Organic EL Material as Solute As described above, it is estimated that the presence of water and oxygen is a fatal defect in the performance of the organic EL device, especially in the life of the light emitting device.
It is no exaggeration to say that the most important thing to be careful about in the coating method is to prevent the mixing of water and oxygen, and for that purpose, the solute remains as a powder like ordinary reagents and chemicals. , Cannot be left in the air.
When we manufacture a coating film-forming element, we usually put the solute substance in a device such as a flask or Schlenk tube that can perform both decompression and Inactive gas purging, and heat gun while depressurizing with a vacuum pump. It is a general method to heat the flask with a medium or the like, seal it with nitrogen, transfer it to a glove box under a nitrogen atmosphere, dissolve it in a dehydrating solvent, and apply the film under nitrogen.
At this time, in order to completely remove oxygen, nitrogen gas is bubbled for dissolution, and a dehydration solvent is also used through an alumina or zeolite absorption tube immediately before dissolution. Such measures are performed in the same or similar manner in pilot plants and actual factories, but as mentioned above, this process takes a very long time and reduces productivity. , We think that solving this part is the biggest challenge.

7. Elementary Techniques Related to the Present Invention [Coating Liquid]
The coating liquid of the present invention is a coating liquid containing an organic compound and an organic solvent, and the dissolved carbon dioxide concentration with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is 1 ppm or more and the saturation concentration with respect to the organic solvent. It is characterized by being within the following range.
Further, the dissolved carbon dioxide concentration is preferably in the range of 5 to 1000 ppm under the above conditions.
When oxygen is present in the coating liquid in an amount of 1 ppm or more, the coating liquid may contain the dissolved carbon dioxide concentration in the range of 1.0 to 100,000 times the dissolved oxygen concentration under the above conditions. It is preferable in terms of the stability of the device created in use. That is, when the coating liquid is prepared in the air, carbon dioxide in the air may also be incorporated into the coating liquid. However, the ratio of carbon dioxide in the atmosphere is very low (about 0.03 to 0.04%), and as a result, the amount of carbon dioxide taken into the coating liquid should also be very low. No case has been reported in which the concentration of dissolved carbon dioxide in the coating liquid was measured. In addition, there is no knowledge that investigated the effect. In the present invention, a state in which the concentration of carbon dioxide is higher than that in the coating liquid of nitrogen and oxygen, which are the main components in the atmosphere, is positively created, and as a result, oxygen and water are taken into the coating liquid. It is expected to have the effect of suppressing.

In the present invention, the dissolved carbon dioxide concentration can be measured by, for example, gas chromatography.

The coating liquid of the present invention is preferably a coating liquid for manufacturing an electronic device or an ink for an inkjet.
The electronic device is preferably a light emitting device such as an organic EL element, a photoelectric conversion element (solar cell), or a liquid crystal display element.

(Organic compound)
The organic compound used in the present invention is not limited to a compound of a specific type and a specific structure, but a compound used in various electronic devices is preferable from the viewpoint of exhibiting the effect of the present invention.
For example, when the coating liquid is a coating liquid for producing an organic EL element, it is preferable that the organic compound is an organic electroluminescence material (hereinafter, also referred to as “organic EL material”). The organic EL material refers to a compound that can be used for an organic electroluminescence layer (hereinafter, also referred to as “organic functional layer” or “organic EL layer”) formed between an anode and a cathode, which will be described later. Further, a light emitting element composed of an anode, a cathode, and an organic EL layer using the organic EL material is called an organic EL element. Examples of compounds used as organic EL materials will be described later.
When the coating liquid is a coating liquid for producing a photoelectric conversion element, the organic compound is preferably a p-type organic semiconductor material or an n-type organic semiconductor material. Examples of these p-type organic semiconductor materials and compounds used as n-type organic semiconductor materials will be described later.

(Organic solvent)
In the present invention, the organic solvent means a medium composed of an organic compound capable of dissolving the above-mentioned organic compound according to the present invention.
Examples of the liquid medium for dissolving or dispersing the organic EL element material according to the present invention include ketones such as methylene chloride, methyl ethyl ketone, tetrahydrofuran and cyclohexanone, fatty acid esters such as ethyl acetate, isopropyl acetate and isobutyl acetate, chlorobenzene and dichlorobenzene. Halogenized hydrocarbons such as 2,2,3,3-tetrafluoro-1-propanol (TFPO), aromatic hydrocarbons such as toluene, xylene, mesitylene and cyclohexylbenzene, and aliphatics such as cyclohexane, decalin and dodecane. Examples thereof include organic solvents such as hydrocarbons, n-butanol, s-butanol, alcohols of t-butanol, DMF, DMSO, etc., and have a boiling point of 50 to 180 ° C. from the viewpoint of suppressing the amount of solvent contained in the device. A range of solvents is preferred.

[Manufacturing method of coating liquid]
The method for producing a coating liquid of the present invention is characterized by having a step of mixing the organic compound and the carbon dioxide (hereinafter, also referred to as a mixing step).
After the mixing step, it is preferable to produce the coating liquid using a solution containing the organic compound.
Further, the method for producing a coating liquid of the present invention is also referred to as a step of separating substances (for example, water, oxygen, and an organic compound) in a solution containing the organic compound using a supercritical fluid (hereinafter, also referred to as a separation step). ) Is preferable.

The mixing step is a step of mixing an organic compound and carbon dioxide. Specifically, it suffices if carbon dioxide can be dissolved in the organic compound. For example, carbon dioxide gas is bubbled in a solution in which an organic solvent and an organic compound are mixed to mix the organic compound and carbon dioxide, or Mixing organic compounds and carbon dioxide using supercritical fluid chromatography can be mentioned.

For bubbling of carbon dioxide gas, for example, it is preferable to bubbling high-purity carbon dioxide gas at a flow rate of 0.01 to 100 ml / min for 1 to 60 minutes.
The coating solution of the present invention can be produced by using the solution obtained by bubbling carbon dioxide gas, that is, the solution of the organic solvent and the organic compound mixed with carbon dioxide by the mixing step. That is, the solution obtained in the mixing step can be used as it is as the coating liquid of the present invention.

As the supercritical fluid chromatography method, a packed column, an open column, and a capillary column can be used.
In the method using a packed column, as shown in FIG. 3, a supercritical fluid 11 containing an organic solvent (including carbon dioxide), a pump 12, a modifier 13 if necessary, and an injector for injecting an organic compound to be separated are injected. A device consisting of 14, a column 15 for separation, a detector 17 if necessary, and a pressure regulating valve 18 may be used. The temperature of the column 15 is adjusted in the column oven 16. As the filler, silica used in a conventional chromatography method, surface-modified silica, or the like can be appropriately selected.
As described above, the method for producing a coating liquid of the present invention preferably includes a step (separation step) of separating an organic compound, water and oxygen using a supercritical fluid containing an organic solvent and carbon dioxide. Then, the coating liquid of the present invention can be produced by using the solution containing the separated organic compound and the organic solvent (including carbon dioxide). That is, the solution obtained in the mixing step can be used as it is as the coating liquid of the present invention.

In the present invention, the supercritical fluid is a substance in a supercritical state.
Here, the supercritical state will be described. A substance changes between three states of gas, liquid, and solid due to changes in environmental conditions such as temperature and pressure (or volume), which is determined by the balance between intermolecular force and kinetic energy. A state diagram (phase diagram) shows the transition of gas-liquid solid state with temperature on the horizontal axis and pressure on the vertical axis. In it, the three phases of gas, liquid, and solid coexist and are in equilibrium. The point in is called the triple point. If the temperature is higher than the triple point, the liquid and its vapor are in equilibrium. The pressure at this time is the saturated vapor pressure, which is represented by an evaporation curve (vapor pressure line). If the pressure is lower than the pressure represented by this curve, all the liquid will vaporize, and if a pressure higher than this is applied, all the vapor will liquefy. Even if the pressure is kept constant and the temperature is changed, when this curve is exceeded, the liquid becomes vapor and the vapor becomes liquid. This evaporation curve has an end point on the high temperature and high pressure side, and this is called a critical point. The critical point is an important point that characterizes a substance, and the interface between gas and liquid disappears when the liquid and vapor are indistinguishable.
In a state where the temperature is higher than the critical point, it is possible to move between a liquid and a gas without causing a gas-liquid coexistence state.
A fluid that is above the critical temperature and above the critical pressure is called a supercritical fluid, and a temperature / pressure region that gives the supercritical fluid is called a supercritical region. Supercritical fluids can be understood as high-density fluids with high kinetic energy, exhibiting liquid behavior in terms of dissolving solutes and gaseous characteristics in terms of density variability. There are various solvent characteristics of supercritical fluids, but it is important that they have low viscosity, high diffusivity, and excellent permeability to solid materials.

In the supercritical state, for example, in the case of carbon dioxide, the critical temperature (hereinafter, also referred to as Tc) is 31 ° C., the critical pressure (hereinafter, also referred to as Pc) is 7.38 × 10 ⁶ Pa, and propane (Tc = 96.7). ° C., Pc = 43.4 × 10 ⁵ Pa), ethylene (Tc = 9.9 ° C., Pc = 52.2 × 10 ⁵ Pa), etc. Above this region, the fluid has a large diffusion coefficient and low viscosity, and is a substance. Since it moves quickly and reaches the concentration equilibrium and has a high density like a liquid, efficient separation is possible. Moreover, by using a substance that becomes a gas at normal pressure and room temperature such as carbon dioxide, recovery becomes quick. In addition, there are no various obstacles due to the residual trace amount of solvent that is unavoidable in the purification method using a liquid solvent.

As the solvent used as the supercritical fluid, carbon dioxide, dinitrogen monoxide, ammonia, water, methanol, ethanol, 2-propanol, ethane, propane, butane, hexane, pentane and the like are preferably used, among which carbon dioxide is used. Can be preferably used.
It is possible to use one kind of solvent as a supercritical fluid alone, or to add a substance called an entrainer, a so-called modifier for adjusting the polarity.
Examples of the entrainer include hydrocarbon solvents such as hexane, cyclohexane, benzene and toluene, halogenated hydrocarbon solvents such as methyl chloride, dichloromethane, dichloroethane and chlorobenzene, and alcohol solvents such as methanol, ethanol, propanol and butanol. Ether solvents such as diethyl ether and tetrahydrofuran, acetal solvents such as acetaldehyde diethyl acetal, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate and butyl acetate, and carboxylic acids such as formic acid, acetic acid and trifluoroacetic acid. Examples thereof include system solvents, nitrogen compound solvents such as acetonitrile, pyridine, N, N-dimethylformamide, sulfur compound solvents such as carbon disulfide and dimethyl sulfoxide, and water, nitric acid, sulfuric acid and the like.

The operating temperature of the supercritical fluid is basically not particularly limited as long as it is above the temperature at which the organic compound of the present invention dissolves, but if the temperature is too low, the solubility of the organic compound in the supercritical fluid becomes poor. In some cases, and if the temperature is too high, the organic compound may be decomposed. Therefore, the operating temperature range is preferably 20 to 600 ° C.

The working pressure of the supercritical fluid is not particularly limited as long as it is equal to or higher than the critical pressure of the substance to be used, but if the pressure is too low, the solubility of the organic compound in the supercritical fluid may be poor, and the solubility of the organic compound in the supercritical fluid may be poor. If the pressure is too high, problems may occur in terms of durability of the manufacturing apparatus, safety during operation, and the like. Therefore, the working pressure is preferably 1 to 100 MPa.

The device using the supercritical fluid is not limited as long as it has a function of allowing the organic compound to come into contact with the supercritical fluid and dissolve in the supercritical fluid. For example, the supercritical fluid is used in a closed system. It is possible to use a batch method to be used, a distribution method in which a supercritical fluid is circulated, a composite method in which a batch method and a distribution method are combined, and the like.

[Ink for making electronic devices]
The ink for manufacturing an electronic device of the present invention is characterized by containing the above-mentioned coating liquid. That is, the ink for manufacturing an electronic device of the present invention is characterized in that it is derived from the above-mentioned coating liquid.
The electronic device is preferably a light emitting device, and more preferably an organic EL element, a photoelectric conversion element, or the like.
Each layer constituting the electronic device can be formed by an inkjet method using an ink for manufacturing an electronic device containing the coating liquid of the present invention.

[Electronic device]
The electronic device of the present invention is characterized by having an organic functional layer formed by using the coating liquid. That is, the electronic device of the present invention is characterized by having an organic functional layer derived from the coating liquid, in other words, having an organic functional layer obtained by forming a coating film of the coating liquid.
The electronic device is preferably a light emitting device, and more preferably an organic EL element, a photoelectric conversion element, or the like.

[Organic EL element]
The organic EL device of the present invention is characterized by having an organic functional layer formed by using the coating liquid. That is, the organic EL device of the present invention is characterized by having an organic functional layer derived from the coating liquid, in other words, having an organic functional layer formed by coating the coating liquid.
The details of the organic EL element will be described below.
As described above, the organic EL element of the present invention has an anode, a cathode, and one or more organic functional layers (also referred to as "organic compound layer" and "organic EL layer") between these electrodes on a substrate. Has a structure.

(substrate)
The substrate that can be used for the organic EL element of the present invention is not particularly limited, but a glass substrate, a plastic substrate, or the like can be used, and it may be transparent or opaque. When light is taken out from the substrate side, the substrate is preferably transparent. Examples of the transparent substrate preferably used include glass, quartz, and a transparent plastic substrate. Further, as the substrate, to prevent oxygen and water from entering from the substrate side, JIS Z-0208 in test according to, the thickness of the water vapor permeability at 1μm or more ^{1g / (m 2 · 24h ·} atm ) (25 ° C.) or less is preferable.

Specific examples of the glass substrate include non-alkali glass, low-alkali glass, soda lime glass and the like. Of these, non-alkali glass is preferable from the viewpoint of less adsorption of water, but any of these may be used as long as it is sufficiently dried.

Plastic substrates have been attracting attention in recent years because of their high flexibility, light weight, and resistance to cracking, and their ability to further reduce the thickness of organic EL elements.
The resin film used as the base material of the plastic substrate is not particularly limited, and for example, polyester such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, and cellulose triacetate (TAC). ), Cellulosic acetate butyrate, Cellulosic acetate propionate (CAP), Cellulose acetate phthalate, Cellulous nitrate and other cellulose esters or derivatives thereof, Polyvinylidene chloride, Polypolyalcohol, Polyethylenevinyl alcohol, Syndiotactic polystyrene, Polycarbonate , Norbornen resin, polymethylpentene, polyether ketone, polyimide, polyethersulfone (PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or poly Examples thereof include allylates and organic-inorganic hybrid resins.

Examples of the organic-inorganic hybrid resin include those obtained by combining an organic resin with an inorganic polymer (for example, silica, alumina, titania, zirconia, etc.) obtained by a sol-gel reaction. Of these, norbornene (or cycloolefin-based) resins such as Arton (manufactured by JSR Corporation) or Appel (manufactured by Mitsui Chemicals, Inc.) are particularly preferable.

The plastic substrate usually produced has a relatively high moisture permeability, and may contain moisture inside the substrate. Therefore, when such a plastic substrate is used, it is preferable to provide a film (hereinafter referred to as "barrier film" or "water vapor sealing film") that suppresses the intrusion of water vapor, oxygen, etc. on the resin film.

The material constituting the barrier film is not particularly limited, and an inorganic substance, an organic film, or a hybrid of both of them is used. A film may be formed, and the water vapor permeability (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) measured by a method according to JIS K 7129-1992 is 0.01 g / (. preferably m ² · 24h) or less of the barrier film, and further, the measured oxygen permeability by the method based on JIS K 7126-1987 ^{is, 1 × 10 -3 mL / (} m 2 · 24h · atm) or less, the water vapor permeability is preferably a high barrier film of ^{1 × 10 -5 g / (m} 2 · 24h) or less

The material constituting the barrier film is not particularly limited as long as it is a material that causes deterioration of the element such as moisture and oxygen but has a function of suppressing infiltration, and is, for example, a metal oxide, a metal oxynitride, a metal nitride, or the like. Inorganic substances, organic substances, or hybrid materials of both can be used.
Examples of the metal oxide, metal oxynitride or metal nitride include metal oxides such as silicon oxide, titanium oxide, indium oxide, tin oxide, indium tin oxide (ITO) and aluminum oxide, and metal nitrides such as silicon nitride. Examples thereof include metal nitrides such as silicon oxynitride and titanium oxynitride.

Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of an organic material. The stacking order of the inorganic layer and the organic layer is not particularly limited, but it is preferable to stack the inorganic layer and the organic layer alternately a plurality of times.

Barrier film was measured by the method based on JIS K 7129-1992, the water vapor transmission rate (25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is 0.01g ^/ (m 2 · 24h) preferably less a barrier film, and further, the oxygen permeability measured in compliance with the method provided in JIS K 7126-1987 ^{is, 10 -3 mL / (m 2} · 24h · atm) or less, the water vapor permeability but the ^{10 -5 g / (m 2 ·} 24h) or less of the resin film is preferably a high barrier film, a method of providing a barrier film is not particularly limited, and may but in any way, for example, vacuum Vapor deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma polymerization method, CVD method (chemical vapor deposition: for example, plasma CVD method) , Laser CVD method, thermal CVD method, etc.), coating method, sol-gel method, etc. can be used. Of these, the method by plasma CVD treatment at atmospheric pressure or near atmospheric pressure is preferable from the viewpoint that a dense film can be formed.

Examples of the opaque substrate include a metal plate such as aluminum and stainless steel, a film or opaque resin substrate, and a ceramic substrate.

(anode)
As the anode of the organic EL element, a metal having a large work function (4 eV or more), an electrically conductive compound of a metal, or a mixture thereof as an electrode material is preferably used. Here, the "metal electrically conductive compound" refers to a compound of a metal and another substance having electrical conductivity, and specifically, for example, a metal oxide, a halide, or the like. Refers to those having electrical conductivity.

Specific examples of such an electrode material include metals such as Au and conductive transparent materials such as _{CuI, indium tin oxide (ITO), SnO 2, and ZnO.} The anode can be produced by forming a thin film made of these electrode substances on the substrate by a known method such as thin film deposition or sputtering.

Further, a pattern having a desired shape may be formed on this thin film by a photolithography method, and when pattern accuracy is not required so much (about 100 μm or more), the desired shape may be formed during vapor deposition or sputtering of the electrode material. The pattern may be formed through a mask.

When extracting light from the anode, it is desirable to increase the transmittance to more than 10%. The sheet resistance as an anode is several hundred Ω / sq. The following is preferable. Further, the film thickness of the anode depends on the constituent material, but is usually selected in the range of 10 nm to 1 μm, preferably 10 nm to 200 nm.

(Organic functional layer)
The organic functional layer (also referred to as "organic EL layer" or "organic compound layer") includes at least a light emitting layer, but in a broad sense, the light emitting layer is when an electric current is passed through an electrode composed of a cathode and an anode. Specifically, it refers to a layer containing an organic compound that emits light when an electric current is passed through an electrode composed of a cathode and an anode.

The organic EL device used in the present invention may have a hole injection layer, an electron injection layer, a hole transport layer and an electron transport layer in addition to the light emitting layer, if necessary, and these layers are cathodes. It has a structure sandwiched between an electron and an anode.

In particular,
(I) Anode / light emitting layer / cathode (ii) anode / hole injection layer / light emitting layer / cathode (iii) anode / light emitting layer / electron injection layer / cathode (iv) anode / hole injection layer / light emitting layer / electron Injection layer / cathode (v) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (vi) anode / hole transport layer / light emitting layer / electron transport layer / cathode, etc. The structure of.

Further, a cathode buffer layer (for example, lithium fluoride) may be inserted between the electron injection layer and the cathode, and an anode buffer layer (for example, copper phthalocyanine or the like) may be inserted between the anode and the hole injection layer. ) May be inserted.

(Light emitting layer)
The light emitting layer according to the present invention is a layer in which electrons and holes injected from an electrode or an electron transporting layer and a hole transporting layer are recombined to emit light, and the light emitting portion is in the layer of the light emitting layer. May also be the interface between the light emitting layer and the adjacent layer. The light emitting layer may be a layer having a single composition, or may have a laminated structure composed of a plurality of layers having the same or different compositions.

The light emitting layer itself may be provided with functions such as a hole injection layer, an electron injection layer, a hole transport layer, and an electron transport layer. That is, (1) an injection function capable of injecting holes through the anode or hole injection layer and electrons being injected from the cathode or electron injection layer when an electric field is applied to the light emitting layer, (2) injection. At least one of a transport function that moves electric charges (electrons and holes) by the force of an electric field, and (3) a light emitting function that provides a field for recombination of electrons and holes inside the light emitting layer and connects this to light emission. Functions may be added. The light emitting layer may have a difference in the ease of injecting holes and the ease of injecting electrons, and may have different transport functions represented by the mobility of holes and electrons. , Which has a function of transferring at least one of the charges is preferable.

The type of light emitting material used for this light emitting layer is not particularly limited, and conventionally known light emitting materials for organic EL devices can be used. Such light emitting materials are mainly organic compounds, and depending on the desired color tone, for example, Macromol. Symp. Examples include the compounds described in Vol. 125, pp. 17-26. Further, the light emitting material may be a polymer material such as p-polyphenylene vinylene or polyfluorene, and further, a polymer material in which the light emitting material is introduced into a side chain or a polymer material in which the light emitting material is used as a main chain of a polymer is used. You may use it. As described above, since the light emitting material may have a hole injection function and an electron injection function in addition to the light emission performance, most of the hole injection materials and electron injection materials described later can also be used as the light emitting material. Can be used.

In the layer constituting the organic EL element, when the layer is composed of two or more kinds of organic compounds, the main component is referred to as a host, the other components are referred to as a dopant, and the host and the dopant are used in combination in the light emitting layer of the present patent. The mixing ratio of the dopant of the light emitting layer (hereinafter, also referred to as light emitting dopant) with respect to the host compound as the main component is preferably 0.1 to less than 30% by mass in terms of mass.

Dopants used in the light emitting layer are roughly classified into two types: a fluorescent dopant that emits fluorescence and a phosphorescent dopant that emits phosphorescence.

Typical examples of fluorescent dopants are coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squallium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, and perylene dyes. , Fluorescein-based dyes, polythiophene-based dyes, rare earth complex-based phosphors, and other known fluorescent compounds.

In the present invention, it is preferable that at least one light emitting layer contains a phosphorescent compound.

In the present invention, the phosphorescent compound is a compound in which light emission from the excited triplet is observed, and the phosphorescence quantum yield is 0.001 or more at 25 ° C. The phosphorus photon yield is preferably 0.01 or more, more preferably 0.1 or more. The phosphorus photon yield can be measured by the method described on page 398 (1992 edition, Maruzen) of Spectroscopy II of the 4th edition Experimental Chemistry Course 7. The phosphorescent quantum yield in a solution can be measured using various solvents, but the phosphorescent compound used in the present invention may achieve the above phosphorescent quantum yield in any of any solvents.

The phosphorescent dopant is a phosphorescent compound, and as a typical example thereof, it is preferably a complex compound containing a metal of Group 8 to 10 in the periodic table of elements, and more preferably an iridium compound or an osmium compound. , A rhodium compound, a palladium compound, or a platinum compound (platinum complex-based compound), preferably an iridium compound, a rhodium compound, or a platinum compound, and most preferably an iridium compound.

Examples of dopants are the compounds described in the following literature or patent gazettes. J. Am. Chem. Soc. Vol. 123, pp. 4304 to 4312, International Publication No. 2000/70655, 2001/93642, 2002/02714, 2002/15645, 2002/44189, 2002/081488, JP-A-2002-280178, 2001- 181616, 2002-280179, 2001-181617, 2002-280180, 2001-247859, 2002-299060, 2001-313178, 2002-302671 No. 2001-345183, 2002-324679, 2002-332291, 2002-502484, 2002-332292, 2002-83648, 2002-540572. No., JP-A-2002-117978, No. 2002-338588, No. 2002-170684, No. 2002-352960, No. 2002-50483, No. 2002-100476, No. 2002-173674. No. 2002-359082, 2002-175884, 2002-363552, 2002-184582, 2003-7469, 2002-525808, 2003- 7471, 2002-525833, 2003-31366, 2002-226495, 2002-234894, 2002-23507, 2002-241751, 2001 -319779, 2001-319780, 2002-62824, 2002-16744, 2002-203679, 2002-343572, 2002-203678, etc.

Specific examples of phosphorescent dopants are given below, but the present invention is not limited thereto.

Only one type of light emitting dopant may be used, or a plurality of types may be used, and by simultaneously extracting light emitted from these dopants, a light emitting element having a plurality of maximum light emission wavelengths can be configured. Further, for example, both a phosphorescent dopant and a fluorescent dopant may be added. When a plurality of light emitting layers are laminated to form an organic EL element, the light emitting dopants contained in each layer may be the same or different, or may be of a single type or a plurality of types. ..

Further, a polymer material in which the light emitting dopant is introduced into a polymer chain or the light emitting dopant is used as a main chain of a polymer may be used.

Examples of the host compound include those having a basic skeleton such as a carbazole derivative, a triarylamine derivative, an aromatic borane derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, and an oligoarylene compound, and electron transport described later. Materials and hole transporting materials are also examples of suitable examples. When applied to a blue or white light emitting element, display device and lighting device, the fluorescence maximum wavelength of the host compound is preferably 415 nm or less, and when a phosphorescent dopant is used, 0- of the phosphorescence of the host compound is used. It is more preferable that the 0 band is 450 nm or less. As the light emitting host, a compound having hole transporting ability and electron transporting ability, preventing the wavelength of light emission from being lengthened, and having a high Tg (glass transition temperature) is preferable.

As a specific example of the light emitting host, for example, the compounds described in the following documents are suitable.

JP 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357977, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002. 2002-105445, 2002-343568, 2002-141173, 2002-352957, 2002-203683, 2002-363227, 2002-231453, 2003 -3165, 2002-234888, 2003-27048, 2002-255934, 2002-260861, 2002-280183, 2002-299060, 2002- 302516, 2002-305083, 2002-305084, 2002-308837, etc.

The luminescent dopant may be dispersed throughout the layer containing the host compound, or may be partially dispersed. A compound having yet another function may be added to the light emitting layer.

A light emitting layer can be formed by thinning the above material by a known method such as a vapor deposition method, a spin coating method, a casting method, an LB method, an inkjet transfer method, or a printing method. The light emitting layer is preferably a molecular deposition film. Here, the molecular deposition film is a thin film deposited and formed from the vapor phase state of the compound, and a film solidified and formed from the molten state or the liquid phase state of the compound. Usually, this molecular deposition film and the thin film (molecular cumulative film) formed by the LB method can be distinguished by the difference in the aggregated structure and the higher-order structure and the functional difference caused by the difference.

In the present invention, it is preferable to use the phosphorescent dopant and the host compound which are the above-mentioned light emitting materials as the organic compound of the present invention. That is, it is preferable to form the light emitting layer by applying a solution containing the phosphorescent dopant, the host compound, and an organic solvent by coating such as spin coating because the light emitting layer made of a molecular volume film can be formed. .. Then, in the coating liquid containing the phosphorescent dopant and the host compound and the organic solvent, the concentration of dissolved carbon dioxide with respect to the organic solvent under atmospheric pressure conditions of 50 ° C. or lower is set to 1 ppm to the saturation concentration with respect to the organic solvent. Is preferable.
As a means for setting the dissolved carbon dioxide concentration in the above range, as described above, a method of bubbling carbon dioxide gas into a solution containing a phosphorescent dopant and a host compound and an organic solvent, or a method containing an organic solvent and carbon dioxide is contained. Examples thereof include a supercritical fluid chromatography method using a supercritical fluid.

(Hole injection layer and hole transport layer)
The hole injection material used for the hole injection layer has either hole injection or electron barrier property. Further, the hole transport material used for the hole transport layer has an electron barrier property and also has a function of transporting holes to the light emitting layer. Therefore, in the present invention, the hole transport layer is included in the hole injection layer. The hole injection material and the hole transport material may be either an organic substance or an inorganic substance. Specifically, for example, triazole derivative, oxadiazole derivative, imidazole derivative, polyarylalkane derivative, pyrazoline derivative, pyrazolone derivative, phenylenediamine derivative, arylamine derivative, amino-substituted chalcone derivative, oxazole derivative, styrylanthracene derivative, fluorenone derivative. , Hydrazone derivatives, Stilben derivatives, Silazan derivatives, aniline-based copolymers, porphyrin compounds, thiophene oligomers and other conductive polymer oligomers. Of these, arylamine derivatives and porphyrin compounds are preferred. Among the arylamine derivatives, aromatic tertiary amine compounds and styrylamine compounds are preferable, and aromatic tertiary amine compounds are more preferable.

Typical examples of the above aromatic tertiary amine compound and styrylamine compound are N, N, N', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'. -Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1- Bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N', N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis (4-di-p-) Trillaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ′ -Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) biphenyl N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4'-[4- (di-p-tolylamino) styryl] stilben; 4-N, N-diphenylamino -(2-Diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostylben; N-phenylcarbazole, as well as the two condensed aromatics described in US Pat. No. 5,061569. Those having a ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (hereinafter abbreviated as α-NPD), described in JP-A-4-308688. Examples include 4,4', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) in which three triphenylamine units are linked in a starburst type. Further, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material.

Further, in the present invention, the hole transport material of the hole transport layer preferably has a fluorescence maximum wavelength of 415 nm or less. That is, the hole transporting material is preferably a compound having a hole transporting ability, preventing the wavelength of light emission from being lengthened, and having a high Tg.

As the hole injection layer and the hole transport layer, the hole injection material and the hole transport material are known, for example, vacuum deposition method, spin coating method, casting method, LB method, inkjet method, transfer method, printing method and the like. It can be formed by thinning the film according to the above method.
Further, in the present invention, it is preferable to use the above-mentioned hole injection material and hole transport material as the organic compound of the present invention. That is, it is preferable that the hole transport layer (or hole injection layer) is formed by applying a solution containing the hole transport material (or hole injection material) and an organic solvent, such as spin coating. In a coating solution containing a hole transport material (or a hole injection material) and an organic solvent, the concentration of dissolved carbon dioxide in the organic solvent under atmospheric pressure conditions of 50 ° C. or lower shall be 1 ppm to the saturation concentration with respect to the organic solvent. Is preferable.
As a means for setting the dissolved carbon dioxide concentration in the above range, as described above, a method of bubbling carbon dioxide gas into a solution containing a hole transporting material and an organic solvent, or a supercritical containing an organic solvent and carbon dioxide. A supercritical fluid chromatography method using a fluid can be mentioned.

The thickness of the hole injection layer and the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm. The hole injection layer and the hole transport layer may have a one-layer structure composed of one or more of the above materials, respectively, or a laminated structure composed of a plurality of layers having the same composition or a different composition. May be good. When both the hole injection layer and the hole transport layer are provided, different materials are usually used among the above materials, but the same material may be used.

(Electron injection layer and electron transport layer)
The electron injection layer may have a function of transferring electrons injected from the cathode to the light emitting layer, and as the material thereof, any conventionally known compound can be selected and used. Examples of materials used for this electron-injected layer (hereinafter, also referred to as electron-injected materials) include heterocyclic tetracarboxylic acid anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, and naphthalene perylene, and carbodiimides. , Freolenilidene methane derivative, anthraquinodimethane and antron derivative, oxadiazole derivative and the like.

Further, a series of electron transporting compounds described in JP-A-59-194393 are disclosed as materials for forming a light emitting layer in the publication, but as a result of examination by the present inventors, electron injection It was found that it could be used as a material. Further, among the above oxadiazole derivatives, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is replaced with a sulfur atom, and a quinoxalin derivative having a quinoxalin ring known as an electron-withdrawing group can also be used as an electron injection material.

Further, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum ( _{abbreviated as Alq 3} ), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-). Kinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metal of these metal complexes are In. , Mg, Cu, Ca, Sn, Ga or Pb can also be used as the electron injection material.

In addition, metal-free or metal phthalocyanine, or those whose terminals are substituted with an alkyl group, a sulfonic acid group, or the like can also be preferably used as the electron injection material. Further, similarly to the hole injection layer, inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as the electron injection material.

The preferred compound used in the electron transport layer preferably has a fluorescence maximum wavelength of 415 nm or less. That is, the compound used for the electron transport layer is preferably a compound having an electron transport ability, preventing the wavelength of light emission from being lengthened, and having a high Tg.

The electron injection layer is formed by thinning the electron injection material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, an inkjet method, a transfer method, or a printing method. Can be done.
Further, in the present invention, it is preferable to use the above-mentioned electron-injected material as the organic compound of the present invention. That is, it is preferable that the electron injection layer is formed by coating a solution containing the electron injection material and the organic solvent by coating such as spin coating, and the temperature of the coating liquid containing the electron injection material and the organic solvent is 50 ° C. or lower. The concentration of dissolved carbon dioxide with respect to the organic solvent under atmospheric pressure conditions is preferably 1 ppm to the saturation concentration with respect to the organic solvent.
As a means for setting the dissolved carbon dioxide concentration in the above range, as described above, a method of bubbling carbon dioxide gas into a solution containing an electron injection material and an organic solvent, or a supercritical fluid containing an organic solvent and carbon dioxide. A supercritical fluid chromatography method using carbon dioxide can be mentioned.

The thickness of the electron injection layer is not particularly limited, but is usually selected in the range of 5 nm to 5 μm. The electron injection layer may have a one-layer structure composed of one or more of these electron injection materials, or may have a laminated structure composed of a plurality of layers having the same composition or a different composition.

In the present specification, among the electron injection layers, when the ionization energy is larger than that of the light emitting layer, it is referred to as an electron transport layer. Therefore, in the present specification, the electron transport layer is included in the electron injection layer.

The electron transport layer is also referred to as a hole blocking layer (hole block layer), and examples thereof include International Publication No. 2000/70655, JP-A-2001-313178, and JP-A-11-204258. Examples thereof include those described in the same publication No. 11-204359 and page 237 of "Organic EL element and its forefront of industrialization (published by NTS Co., Ltd. on November 30, 1998)". In particular, in a so-called "phosphorescent light emitting device" that uses an orthometal complex-based dopant for the light emitting layer, it is preferable to adopt a configuration having an electron transport layer (hole blocking layer) as described in (v) and (vi) above.

(Buffer layer)
A buffer layer (electrode interface layer) may be present between the anode and the light emitting layer or the hole injection layer, and between the cathode and the light emitting layer or the electron injection layer. The buffer layer is a layer provided between the electrode and the organic layer in order to reduce the driving voltage and improve the luminous efficiency. "Organic EL element and its forefront of industrialization (published by NTS on November 30, 1998)" ) ”, Volume 2, Chapter 2,“ Electrode Materials ”(pages 123 to 166), and includes an anode buffer layer and a cathode buffer layer.

The details of the anode buffer layer are also described in JP-A-9-45479, 9-2660062, 8-288609, etc., and as a specific example, a phthalocyanine buffer layer typified by copper phthalocyanine. , Oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polymer buffer layer using conductive polymer such as polyaniline (emeraldine) and polythiophene, and the like.

The details of the cathode buffer layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, etc., and specifically, a metal typified by strontium, aluminum, or the like. Examples thereof include a buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide.

The buffer layer is preferably a very thin film, and although it depends on the material, the thickness thereof is preferably in the range of 0.1 to 100 nm. Further, in addition to the above basic constituent layers, layers having other functions may be appropriately laminated, if necessary.

(cathode)
As described above, as the cathode of the organic EL element, a metal having a small work function (less than 4 eV) (hereinafter referred to as an electron-injectable metal), an alloy, an electrically conductive compound of the metal, or a mixture thereof is generally used as an electrode material. Things are used.

Specific examples of such electrode materials include sodium, magnesium, lithium, aluminum, indium, rare earth metals, sodium-potassium alloy, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum. / Aluminum oxide (Al ₂ O ₃ ) mixture, lithium / aluminum mixture and the like.

In the present invention, those listed above may be used as the electrode material of the cathode, but from the viewpoint of more effectively exerting the effect of the present invention, the cathode may contain a Group 13 metal element. preferable. That is, in the present invention, as will be described later, the surface of the cathode is oxidized with oxygen gas in a plasma state to form an oxide film on the surface of the cathode, thereby preventing further oxidation of the cathode and improving the durability of the cathode. Can be made to.

Therefore, the electrode material of the cathode is preferably a metal having preferable electron injection properties required for the cathode and capable of forming a dense oxide film.

Specific examples of the electrode material of the cathode containing the Group 13 metal element include aluminum, indium, magnesium / aluminum mixture, magnesium / indium mixture, and aluminum / aluminum oxide (Al ₂ O ₃ ) mixture. , Lithium / aluminum mixture and the like. The mixing ratio of each component of the mixture can be a conventionally known ratio as the cathode of the organic EL element, but the mixing ratio is not particularly limited. The cathode can be produced by forming a thin film on the organic compound layer (organic EL layer) by forming the electrode material on the organic compound layer (organic EL layer) by a method such as vapor deposition or sputtering.

The sheet resistance as a cathode is several hundred Ω / sq. The following is preferable, and the film thickness is usually selected in the range of 10 nm to 1 μm, preferably 50 to 200 nm. It is preferable to make either the anode or the cathode of the organic EL element transparent or translucent in order to transmit the emitted light because the luminous efficiency is improved.

A preferred example of manufacturing a display device made of an organic EL element manufactured by using the coating liquid (organic EL material) of the present invention will be described.

[Method for manufacturing organic EL elements]
As an example of the method for manufacturing the organic EL device of the present invention, a method for manufacturing the organic EL device including the anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

First, a thin film made of a desired electrode substance, for example, an anode substance, is formed on a suitable substrate by a method such as thin film deposition or sputtering so as to have a thickness of 1 μm or less, preferably 10 to 200 nm, to prepare an anode. To do. Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are element materials, is formed on this.

As a method for thinning these organic compound thin films, as described above, there are a spin coating method, a casting method, an inkjet method, a thin film deposition method, a printing method and the like, but a uniform film can be easily obtained and pinholes are formed. The vacuum vapor deposition method or the spin coating method is preferable from the viewpoint of difficulty in forming, and in the present invention, the spin coating method is particularly preferable from the viewpoint that the coating liquid of the present invention can be used.
Further, a different film forming method may be applied to each layer. The case of employing an evaporation method in the deposition, the deposition conditions may vary due to kinds of materials used, generally boat temperature 50 to 450 the degree of vacuum ¹⁰ -6 ^{to 10} -2 Pa, the deposition rate 0.01 It is desirable to appropriately select in the range of ~ 50 nm / sec, substrate temperature -50 to 300 ° C., and thickness 0.1 nm to 5 μm.

After forming these layers, a thin film made of a material for a cathode is formed on the layer so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided by a method such as vapor deposition or sputtering. Therefore, a desired organic EL element can be obtained. The organic EL element is preferably manufactured from the hole injection layer to the cathode by one vacuuming, but it may be taken out in the middle and a different film forming method may be applied. At that time, consideration must be given to performing the work in a dry inert gas atmosphere.

[Encapsulation of organic EL element]
The sealing means for the organic EL element is not particularly limited, but for example, after sealing the outer peripheral portion of the organic EL element with a sealing adhesive, the sealing member is formed so as to cover the light emitting region of the organic EL element. There is a method of arranging.

Examples of the sealing adhesive include acrylic acid-based oligomers, photocurable and thermosetting adhesives having a reactive vinyl group of methacrylic acid-based oligomers, and moisture-curable adhesives such as 2-cyanoacrylic acid ester. Can be mentioned. In addition, heat and chemical curing type (two-component mixture) such as epoxy type can be mentioned. Further, hot melt type polyamide, polyester and polyolefin can be mentioned. In addition, a cation-curable type ultraviolet-curable epoxy resin adhesive can be mentioned.

As the sealing member, a polymer film and a metal film can be preferably used from the viewpoint that the organic EL element can be thinned.

In the gap between the sealing member and the light emitting region of the organic EL element, in addition to the sealing adhesive, in the gas phase and liquid phase, an inert gas such as nitrogen or argon, fluorine hydrocarbon, silicon oil, etc. It is also possible to inject a non-active liquid. Further, the gap between the sealing member and the display region of the organic EL element can be evacuated, or a hygroscopic compound can be sealed in the gap.

[Display device]
In the multicolor display device using the organic EL element of the present invention, a shadow mask is provided only when the light emitting layer is formed, and since the other layers are common, patterning of the shadow mask or the like is unnecessary, and the vapor deposition method, the casting method, etc. A film can be formed by a spin coating method, an inkjet method, a printing method, or the like.

When patterning only the light emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, or a printing method is preferable. When the vapor deposition method is used, patterning using a shadow mask is preferable.

It is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order.

When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Further, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The waveform of the alternating current to be applied may be arbitrary.

The multicolor display device can be used as a display device, a display, and various light emitting light sources. Full-color display is possible by using three types of organic EL elements that emit blue, red, and green in the display device and display.

Examples of display devices and displays include televisions, personal computers, mobile devices, AV devices, teletext displays, information displays in automobiles, and the like. In particular, it may be used as a display device for reproducing a still image or a moving image, and the drive method when used as a display device for reproducing a moving image may be either a simple matrix (passive matrix) method or an active matrix method.

Light sources include household lighting, interior lighting, backlights for clocks and liquid crystals, signboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. It can be mentioned, but it is not limited to this.

Further, the organic EL element according to the present invention may be used as an organic EL element having a resonator structure.

The purpose of using the organic EL element having such a resonator structure includes a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processor, a light source of an optical sensor, and the like. Not limited. Further, it may be used for the above purpose by oscillating a laser.

The organic EL element of the present invention may be used as a kind of lamp such as an illumination or an exposure light source, a projection device of a type for projecting an image, or a display device of a type for directly visually recognizing a still image or a moving image. It may be used as a (display). When used as a display device for video reproduction, the drive system may be either a simple matrix (passive matrix) system or an active matrix system. Alternatively, a full-color display device can be manufactured by using two or more kinds of organic EL elements of the present invention having different emission colors.

An example of a display device composed of the organic EL element of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic view showing an example of a display device composed of an organic EL element. It is a schematic diagram of the display of a mobile phone or the like which displays image information by light emission of an organic EL element. The display 41 includes a display unit A having a plurality of pixels, a control unit B that scans an image of the display unit A based on image information, and the like. The control unit B is electrically connected to the display unit A, sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside, and the scanning signal converts the pixels of each scanning line into an image data signal. In response to this, light is emitted in sequence, image scanning is performed, and image information is displayed on the display unit A.

FIG. 5 is a schematic view of the display unit A. The display unit A has a wiring unit including a plurality of scanning lines 55 and data lines 56, a plurality of pixels 53, and the like on the substrate. The main members of the display unit A will be described below.

FIG. 5 shows a case where the light emitted from the pixel 53 is taken out in the direction of the white arrow (downward). The scanning lines 55 and the plurality of data lines 56 of the wiring portion are each made of a conductive material, and the scanning lines 55 and the data lines 56 are orthogonal to each other in a grid pattern and are connected to the pixel 53 at orthogonal positions (details are shown in FIG. Not shown). When a scanning signal is applied from the scanning line 55, the pixel 53 receives an image data signal from the data line 56 and emits light according to the received image data. Full-color display is possible by appropriately arranging pixels in the red region, pixels in the green region, and pixels in the blue region of the emission color on the same substrate.

Next, the light emitting process of the pixel will be described.
FIG. 6 is a schematic diagram of pixels. The pixel includes an organic EL element 60, a switching transistor 61, a drive transistor 62, a capacitor 63, and the like. As the organic EL element 60 for a plurality of pixels, red, green, and blue light emitting organic EL elements are used, and by arranging them side by side on the same substrate, full-color display can be performed.

In FIG. 6, an image data signal is applied from the control unit B (not shown in FIG. 6 but shown in FIG. 4) to the drain of the switching transistor 61 via the data line 56. Then, when a scanning signal is applied from the control unit B to the gate of the switching transistor 61 via the scanning line 55, the driving of the switching transistor 61 is turned on, and the image data signal applied to the drain is the capacitor 63 and the driving transistor 62. It is transmitted to the gate of.

By transmitting the image data signal, the capacitor 63 is charged according to the potential of the image data signal, and the drive transistor 62 is driven on. In the drive transistor 62, the drain is connected to the power supply line 67, the source is connected to the electrode of the organic EL element 60, and the power supply line 67 is connected to the organic EL element 60 according to the potential of the image data signal applied to the gate. Current is supplied.

When the scanning signal is transferred to the next scanning line 55 by the sequential scanning of the control unit B, the driving of the switching transistor 61 is turned off. However, even if the drive of the switching transistor 61 is turned off, the capacitor 63 holds the potential of the charged image data signal, so that the drive of the drive transistor 62 is kept on and the next scan signal is applied. The light emission of the organic EL element 60 continues until. When the scanning signal is applied next by the sequential scanning, the driving transistor 62 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 60 emits light. That is, for the light emission of the organic EL element 60, the switching transistor 61 and the drive transistor 62, which are active elements, are provided for the organic EL element 60 of each of the plurality of pixels, and the plurality of pixels 53 (not shown in FIG. 6). , FIG. 5) Each organic EL element 60 emits light. Such a light emitting method is called an active matrix method.

Here, the light emission of the organic EL element 60 may be light emission of a plurality of gradations by a multi-valued image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. It may be.

Further, the potential of the capacitor 63 may be continuously maintained until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

The present invention is not limited to the active matrix method described above, and may be a passive matrix type light emitting drive in which the organic EL element emits light in response to the data signal only when the scanning signal is scanned.

FIG. 7 is a schematic view of a display device based on the passive matrix method. In FIG. 7, a plurality of scanning lines 55 and a plurality of image data lines 56 are provided in a grid pattern so as to face each other with the pixel 53 interposed therebetween. When the scanning signal of the scanning line 55 is applied by the sequential scanning, the pixel 53 connected to the applied scanning line 55 emits light according to the image data signal. In the passive matrix method, the pixel 53 does not have an active element, and the manufacturing cost can be reduced.

[Photoelectric conversion element and solar cell]
The photoelectric conversion element of the present invention is characterized by having an organic functional layer formed by using the coating liquid. That is, the photoelectric conversion element of the present invention is characterized by having an organic functional layer derived from the coating liquid, in other words, having an organic functional layer formed by coating the coating liquid.
The details of the photoelectric conversion element and the solar cell will be described below.
FIG. 8 is a cross-sectional view showing an example of a solar cell having a single configuration (a configuration in which the bulk heterojunction layer is one layer) composed of a bulk heterojunction type organic photoelectric conversion element.
In FIG. 8, the bulk heterojunction type organic photoelectric conversion element 200 has a transparent electrode (anode) 202, a hole transport layer 207, a photoelectric conversion portion 204 of the bulk heterojunction layer, and an electron transport layer (or an electron transport layer) on one surface of the substrate 201. The buffer layer) 208 and the counter electrode (cathode) 203 are sequentially laminated.

The substrate 201 is a member that holds the transparent electrodes 202, the photoelectric conversion unit 204, and the counter electrode 203 that are sequentially laminated. In the present embodiment, since the light to be photoelectrically converted is incident from the substrate 201 side, the substrate 201 can transmit the photoelectrically converted light, that is, with respect to the wavelength of the light to be photoelectrically converted. It is preferably a transparent member. As the substrate 201, for example, a glass substrate, a resin substrate, or the like is used. The substrate 201 is not essential, and for example, the bulk heterojunction type organic photoelectric conversion element 200 may be configured by forming the transparent electrodes 202 and the counter electrode 203 on both sides of the photoelectric conversion unit 204.

The photoelectric conversion unit 204 is a layer that converts light energy into electrical energy, and is configured to have a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are described as "an electron donor that, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state). And electron acceptors, which donate or accept electrons by photoreaction, rather than simply donating or accepting electrons like electrodes.

In FIG. 8, the light incident from the transparent electrode 202 via the substrate 201 is absorbed by an electron acceptor or an electron donor in the bulk heterojunction layer of the photoelectric conversion unit 204, and electrons move from the electron donor to the electron acceptor. Then, a hole-electron pair (charge separation state) is formed. The generated charge is due to the internal electric field, for example, when the work functions of the transparent electrode 202 and the counter electrode 203 are different, the potential difference between the transparent electrode 202 and the counter electrode 203 causes electrons to pass between the electron acceptors, and holes to be electron donors. The photocurrent is detected by being carried to different electrodes. For example, when the work function of the transparent electrode 202 is larger than the work function of the counter electrode 203, electrons are transported to the transparent electrode 202 and holes are transported to the counter electrode 203. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. Further, the transport direction of electrons and holes can be controlled by applying an electric potential between the transparent electrode 202 and the counter electrode 203.

Although not shown in FIG. 8, another layer such as a hole block layer, an electron block layer, an electron injection layer, a hole injection layer, or a smoothing layer may be provided.
Further, for the purpose of further improving the solar utilization rate (photoelectric conversion efficiency), a tandem type configuration (a configuration having a plurality of bulk heterojunction layers) in which such photoelectric conversion elements are laminated may be used.
FIG. 9 is a cross-sectional view showing a solar cell including an organic photoelectric conversion element provided with a tandem type bulk heterojunction layer. In the case of the tandem type configuration, the transparent electrode 202 and the first photoelectric conversion unit 209 are sequentially laminated on the substrate 201, the charge recombination layer (intermediate electrode) 205 is laminated, and then the second photoelectric conversion unit 206, Next, by stacking the counter electrode 203, a tandem type configuration can be obtained.

Examples of the material that can be used for the layer as described above include the n-type semiconductor material and the p-type semiconductor material described in paragraphs 0045 to 0113 of Japanese Patent Application Laid-Open No. 2015-149843.

(Method of forming bulk heterojunction layer)
Examples of the method for forming the bulk heterojunction layer in which the electron acceptor and the electron donor are mixed include a thin film deposition method, a coating method (including a casting method and a spin coating method), and the like. Of these, the coating method is preferable in order to increase the area of the interface where the holes and electrons are charged-separated and to produce an element having high photoelectric conversion efficiency. The coating method is also excellent in production speed.
In the present invention, the n-type semiconductor material and the p-type semiconductor material constituting the bulk heterojunction layer can be used as the organic compound of the present invention. That is, it is preferable that the bulk heterojunction layer is formed by coating a solution containing the n-type semiconductor material, the p-type semiconductor material, and an organic solvent, and the n-type semiconductor material, the p-type semiconductor material, and the organic solvent are used. It is preferable that the concentration of dissolved carbon dioxide with respect to the organic solvent under atmospheric pressure conditions of 50 ° C. or lower is set to 1 ppm to the saturation concentration with respect to the organic solvent in the coating solution containing.
As a means for setting the dissolved carbon dioxide concentration in the above range, as described above, a method of bubbling carbon dioxide gas into a solution containing an n-type semiconductor material and a p-type semiconductor material and an organic solvent, or an organic solvent and carbon dioxide. A supercritical fluid chromatography method using a supercritical fluid containing carbon dioxide can be mentioned.

After coating, it is preferable to perform heating in order to remove residual solvent, water and gas, and to improve mobility and lengthen absorption by crystallization of the semiconductor material. When annealed at a predetermined temperature during the manufacturing process, a part of the bulk heterojunction layer is microscopically promoted to be arranged or crystallized, and the bulk heterojunction layer can have an appropriate phase separation structure. As a result, the carrier mobility of the bulk heterojunction layer is improved, and high efficiency can be obtained.

The photoelectric conversion unit (bulk heterojunction layer) 204 may be composed of a single layer in which an electron acceptor and an electron donor are uniformly mixed, but a plurality of electron acceptors and electron donors having different mixing ratios. It may be composed of layers.
Next, the electrodes constituting the organic photoelectric conversion element will be described.

In the organic photoelectric conversion element, the positive charge and the negative charge generated in the bulk heterojunction layer are taken out from the transparent electrode and the counter electrode, respectively, via the p-type organic semiconductor material and the n-type organic semiconductor material, respectively, and function as a battery. To do. Each electrode is required to have characteristics suitable for a carrier passing through the electrode.

(Opposite pole)
In the present invention, the counter electrode (cathode) is preferably an electrode that extracts electrons. For example, when it is used as a cathode, it may be a single layer of a conductive material, but in addition to a material having conductivity, a resin that retains these may be used in combination.

As the counter electrode material, for example, a known conductive material for a cathode described in JP-A-2010-272619A, JP-A-2014-077422, etc. can be used.
As the counter electrode material, for example, a known conductive material for a cathode described in JP-A-2010-272619A, JP-A-2014-077422, etc. can be used.

(Transparent electrode)
In the present invention, the transparent electrode is preferably an anode having a function of extracting holes generated in the photoelectric conversion unit. For example, when used as an anode, it is preferably an electrode that transmits light having a wavelength of 380 to 800 nm. As the material, for example, known materials for anodes described in Japanese Patent Application Laid-Open No. 2010-272619, Japanese Patent Application Laid-Open No. 2014-078742, and the like can be used.

(Intermediate electrode)
Further, as the material of the intermediate electrode required in the case of the tandem structure, a layer using a compound having both transparency and conductivity is preferable.
As the material, for example, known materials for intermediate electrodes described in JP-A-2010-272619A, JP-A-2014-077422, etc. can be used.

Next, materials constituting other than the electrodes and the bulk heterojunction layer will be described.

(Hole transport layer and electron block layer)
In the organic photoelectric conversion element of the present invention, a hole transport layer / electron block layer is provided between the bulk heterojunction layer and the transparent electrode in order to enable more efficient extraction of charges generated in the bulk heterojunction layer. It is preferable to have it.

As the material for the photoelectric conversion element constituting the hole transport layer, for example, known materials described in JP-A-2010-272619, JP-A-2014-07742, etc. can be used.

(Electron transport layer, hole block layer and buffer layer)
The organic photoelectric conversion element of the present invention forms an electron transport layer, a hole block layer, and a buffer layer between the bulk heterojunction layer and the counter electrode to more efficiently extract the electric charge generated in the bulk heterojunction layer. It is preferable to have these layers because it enables.

Further, as the electron transport layer, for example, known materials described in Japanese Patent Application Laid-Open No. 2010-272619, Japanese Patent Application Laid-Open No. 2014-078742, and the like can be used. The electron transport layer may be a hole block layer having a hole block function, which has a rectifying effect so as not to allow holes generated in the bulk heterojunction layer to flow to the opposite electrode side. As the material for forming the hole block layer, for example, a known material described in JP-A-2014-078742 can be used.

(Other layers)
For the purpose of improving the energy conversion efficiency and the life of the device, various intermediate layers may be provided in the device. Examples of the intermediate layer include a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, an exciton block layer, a UV absorption layer, a light reflection layer, a wavelength conversion layer and the like.

(substrate)
When the light to be photoelectrically converted is incident from the substrate side, the substrate is preferably a member capable of transmitting the photoelectrically converted light, that is, a member transparent to the wavelength of the light to be photoelectrically converted. .. The substrate is preferably a glass substrate, a resin substrate, or the like, but it is desirable to use a transparent resin film from the viewpoint of light weight and flexibility.
The transparent resin film that can be preferably used as a transparent substrate in the present invention is not particularly limited, and the material, shape, structure, thickness, and the like thereof can be appropriately selected from known ones. For example, known materials described in Japanese Patent Application Laid-Open No. 2010-272619, Japanese Patent Application Laid-Open No. 2014-078742, and the like can be used.

(Optical functional layer)
The organic photoelectric conversion element of the present invention may have various optical functional layers for the purpose of receiving sunlight more efficiently. As the optical functional layer, for example, an antireflection film, a condensing layer such as a microlens array, a light diffusion layer capable of scattering light reflected by the counter electrode and making it incident on the bulk heterojunction layer again may be provided. Good.

Examples of the antireflection layer, the light-collecting layer, and the light-scattering layer include known antireflection layers, light-collecting layers, and light-scattering layers described in JP-A-2010-272619 and JP-A-2014-07742. Can be used.

(Patterning)
The method and process for patterning the electrodes, power generation layer, hole transport layer, electron transport layer, etc. according to the present invention are not particularly limited. The known methods described can be applied as appropriate.

(Sealing)
Further, since the produced organic photoelectric conversion element is not deteriorated by oxygen, moisture or the like in the environment, it is preferable to seal not only the organic photoelectric conversion element but also the organic electroluminescence element or the like by a known method. For example, the methods described in JP-A-2010-272619, JP-A-2014-077422, and the like can be used.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples shown below, dry air refers to dry air produced using a dry air generator (manufactured by Rika Ikeda Co., Ltd., AT35HS), and atmospheric means in a laboratory set at 25 ° C. and 1 atm. It indicates the atmosphere, and the nitrogen atmosphere refers to the nitrogen atmosphere using nitrogen gas supplied from a G1 grade nitrogen cylinder manufactured by Solar Nissin.

In addition, the structure of the compound used in the examples is shown below.

[Example 1]
In a high-purity nitrogen atmosphere, high-purity carbon dioxide gas (Tayo Nissin, high-purity carbon dioxide gas (Tayo Nissin, high-purity carbon dioxide gas) is used in a solution (s-1) of CBP, 5 g dissolved in 1 L of toluene (Kanto Chemical Co., Inc., dehydrated toluene). > 99.995 vol.%) Was bubbled at a flow rate of 100 mL / min for 10 minutes, and then degassed for 10 minutes to prepare solution s-5.
The amount of carbon dioxide contained in s-1 and s-5 was measured by gas chromatography. Specifically, a bulk packing type S GC Bulk Packing Material (Mesh80-100) manufactured by Waters Corporation was used as a column packing material, and the measurement was performed by an absolute calibration curve method.
The water content of s-1 and s-5 was measured by the Karl Fischer method. The results of each are shown in Table 1.
Further, the various solvents shown in Table 1 were subjected to the same treatment, and those in which high-purity carbon dioxide gas was not bubbled to the various solvents (s-2 to s-4) and those in which the various solvents were bubbled (s-6 to s). -8) was prepared, and the carbon dioxide content and water content of s-2 to s-4 and s-6 to s-8 were measured. The results are shown in Table 1.

The various solvents used are as follows.
Toluene (Kanto Chemical Co., Inc., dehydrated toluene), isobutyl acetate (Kanto Chemical Co., Inc., special grade isobutyl acetate), TFPO (Tokyo Chemical Industry Co., Ltd., 2,2,3,3-tetrafluoro-1-propanol)

From the results shown in Table 1, it can be seen that the water content in the various solvents could be reduced by mixing carbon dioxide with the various solvents.
[Example 2]
After storing s-1 to s-8 prepared in Example 1 for 1 hour under the conditions shown in Table 2, the dissolved oxygen concentration of each sample was measured by gas chromatography. The results of each are shown in Table 2.

From the results shown in Table 2, it can be seen that the organic solvent containing carbon dioxide takes up less oxygen when stored in dry air and the atmosphere.

[Example 3]
A transparent support provided with this ITO transparent electrode after patterning on a substrate (NA45 manufactured by NH Technoglass Co., Ltd.) in which ITO (indium tin oxide) was deposited at 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm. The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone washed for 5 minutes. On this substrate, s-4 produced in Example 1 was formed into a film (thickness: about 40 nm) by an inkjet method, and the mass (w (0)) before the start of drying was measured. Then, the mass (w (t)) when dried at 60 ° C. for t minutes and the mass (w (60)) when vacuum dried for 1 hour were measured.
Using the mass of the substrate vacuum-dried for 1 hour (w (60)), the mass before the start of drying (w (0)), and the mass after drying for t minutes (w (t)), the degree of drying after drying for t minutes. (Dry (101)) was calculated by the following equation.
Dry101 (t) = (1-((w (t) --w (60)) / (w (0) --w (60))) x 100
Similar measurements were made by replacing s-4 with the other solutions listed in Table 3 to obtain the results in Table 3.

From the results shown in Table 3, it can be seen that when the solution of the present invention (ink for manufacturing an electronic device) bubbling carbon dioxide gas is used, the drying time of the ink is shortened.

[Example 4]
<Preparation of coating liquid for hole transport layer (HT layer)>
In a glove box under a nitrogen atmosphere, a solution (solution s-10) in which 600 mg of polyvinylcarbazole (PVK) was dissolved in 100 ml of chlorobenzene was divided into two and treated by the following methods, one of which was used as solution s-11. The other was bubbling carbon dioxide for 10 minutes in a glove box under a nitrogen atmosphere to prepare solution s-12. The carbon dioxide concentration of the solution s-12 was measured by the method of Example 1 and confirmed to contain 200 ppm of carbon dioxide. Further, the solution s-11 and the solution s-12 were each divided into three parts and treated by the following methods to obtain the solutions shown in Table 4.
Treatment 1: Solution s-11 was stored in the prepared nitrogen atmosphere for 30 minutes to obtain solution s-111.
Treatment 2: Solution s-11 was stored in a dry air atmosphere for 30 minutes to obtain solution s-112.
Treatment 3: Solution s-11 was stored in the air for 30 minutes to obtain solution s-113.
Treatment 4: Solution s-12 was stored in the prepared nitrogen atmosphere for 30 minutes to obtain solution s-121.
Treatment 5: Solution s-12 was stored in a dry air atmosphere for 30 minutes to obtain solution s-122.
Treatment 6: Solution s-12 was stored in the air for 30 minutes to give solution s-123.

<Preparation of coating liquid for light emitting layer (EM layer)>
In a glove box under a nitrogen atmosphere, a solution (solution s-20) in which 600 mg of CBP and 30.0 mg of compound Ir-12 were dissolved in 60 ml of toluene / isobutyl acetate (1/1) was divided into two, and the following methods were used for each. One was prepared as solution s-21, and the other was bubbling carbon dioxide in a groove box under a nitrogen atmosphere for 10 minutes to prepare solution s-22. The carbon dioxide concentration of the solution s-22 was measured by the method of Example 1 and confirmed to contain 250 ppm of carbon dioxide. Further, the solution s-21 and the solution s-22 were each divided into three parts and treated by the following methods to obtain the solutions shown in Table 4.
Treatment 11: Solution s-21 was stored in the prepared nitrogen atmosphere for 30 minutes to obtain solution s-211.
Treatment 12: Solution s-21 was stored in a dry air atmosphere for 30 minutes to obtain solution s-212.
Treatment 13: Solution s-21 was stored in the air for 30 minutes to obtain solution s-213.
Treatment 14: Solution s-22 was stored in the prepared nitrogen atmosphere for 30 minutes to obtain solution s-221.
Treatment 15: Solution s-22 was stored in a dry air atmosphere for 30 minutes to obtain solution s-222.
Treatment 16: Solution s-22 was stored in the air for 30 minutes to give solution s-223.

<Coating liquid for electron transport layer (ET layer)>
In a glove box under a nitrogen atmosphere, a solution (solution s-30) in which 200 mg of vasocuproin (BCP) was dissolved in 60 ml of cyclohexane was divided into two, each treated by the following method, and one of them was made into solution s-31. One of them was bubbling carbon dioxide for 10 minutes in a glove box under a nitrogen atmosphere to prepare solution s-32. The carbon dioxide concentration of the solution s-32 was measured by the method of Example 1 and confirmed to contain 180 ppm of carbon dioxide. Further, the solution s-31 and the solution s-32 were each divided into three parts and treated by the following methods to obtain the solutions shown in Table 4.
Treatment 21: Solution s-31 was stored in the prepared nitrogen atmosphere for 30 minutes to obtain solution s-311.
Treatment 22: Solution s-31 was stored in a dry air atmosphere for 30 minutes to obtain solution s-312.
Treatment 23: Solution s-31 was stored in the air for 30 minutes to give solution s-313.
Treatment 24: Solution s-32 was stored in the prepared nitrogen atmosphere for 30 minutes to obtain solution s-321.
Treatment 25: Solution s-32 was stored in a dry air atmosphere for 30 minutes to obtain solution s-322.
Treatment 26: Solution s-32 was stored in the air for 30 minutes to give solution s-323.

<Manufacturing of organic EL element>
This ITO transparent electrode was provided after patterning was performed on a substrate (NA45 manufactured by NH Technoglass Co., Ltd.) in which ITO (indium tin oxide) was deposited at 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode. The transparent support substrate was ultrasonically washed with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone washed for 5 minutes. This substrate was attached to a commercially available spin coater, and the solution was s-111 (10 ml), spin coated (layer thickness: about 40 nm), vacuum dried at 60 ° C. for 1 hour under the conditions of 1000 rpm and 30 seconds, and the hole transport layer was formed. did. Next, using solution s-211 (6 ml), spin coating was performed under the conditions of 1000 rpm for 30 seconds (layer thickness of about 40 nm), and vacuum dried at 60 ° C. for 1 hour to obtain a light emitting layer. Further, using solution s-311 (6 ml), spin-coat (layer thickness: about 10 nm) under the conditions of 1000 rpm and 30 seconds, vacuum dry at 60 ° C. for 1 hour, and form an electron transport layer that also serves as a hole blocking function. Provided.
Subsequently, this substrate was fixed to the substrate holder of _{the vacuum vapor deposition apparatus, 200 mg of Alq 3} was placed in a molybdenum resistance heating boat, and the substrate was attached to the vacuum vapor deposition apparatus. After depressurizing the vacuum chamber to 4 × 10 ^-4 _{Pa, the heating boat containing Alq 3} is energized and heated, and thin-film deposition is performed on the electron transport layer at a vapor deposition rate of 0.1 nm / sec to further layer. An electron injection layer having a thickness of 40 nm was provided. The substrate temperature at the time of vapor deposition was room temperature.
Subsequently, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited to form a cathode to produce an organic EL element 1.
In the production of the organic EL element 1, the organic EL element shown in Table 4 was prepared in the same manner as the organic EL element 1 except that the solution s-111, the solution s-411, and the solution s-311 were replaced with the solutions shown in Table 4. Made.

<Evaluation of organic EL elements>
The organic EL elements shown in Table 4 produced as described above were evaluated as follows, and the results are shown in Table 4.
The produced organic EL element is continuously lit by applying a 10 V DC voltage under a temperature of 23 ° C. and a dry nitrogen gas atmosphere, and the time (hereinafter referred to as luminous life) and luminous efficiency (hereinafter referred to as luminous lifetime) in which the brightness is halved from the luminescence brightness at the start of lit lm / W) was measured, and the results are shown in Table 4. However, the light emission lifetime and the light emission efficiency are represented by relative values with the light emission life and the light emission efficiency of the organic EL element 1 as 100, respectively. The emission brightness was measured using CS-1000 manufactured by Konica Minolta.

From the results shown in Table 4, the organic EL device using the carbon dioxide-containing coating liquid of the present invention has a luminous efficiency and an element when stored in dry air or the atmosphere as compared with the carbon dioxide-free coating liquid under the same conditions. It can be seen that there is little deterioration in the life evaluation results.

[Example 5]
<Purification of compounds for ink>
CBP was fractionated under the following conditions using a supercritical fluid chromatography system manufactured by JASCO Corporation.
Supercritical CO ₂ liquid feed pump: SCF-Get
Fully automatic pressure control valve: SFC-Bpg
Column oven: GC-353B
Injector: 7125i
Column: C18-Silica, 3 μm, 4.6 mm x 250 mm
Moving layer: carbon dioxide / toluene = 9/1
Moving layer flow rate: 3 ml / min
Pressure: 18 MPa
Temperature: 40 ° C
Detection: UV detector (210 nm)
Under the above conditions, a toluene solution containing 10% by mass of CBP and 300 ppm of carbon dioxide was obtained. This solution is referred to as composition 1. Next, the following composition was obtained in the same manner except that CBP was changed to Ir-14, Ir-1, and Ir-15, respectively.
Composition 2: Toluene solution containing 10% by mass of Ir-14 and 300 ppm of carbon dioxide Composition 3: Toluene solution containing 10% by mass of Ir-1 and 300 ppm of carbon dioxide Composition 4: 10% by mass of Ir-15, Toluene solution containing 300 ppm of carbon dioxide Next, a TFPO solution containing 10% by mass of BCP and 300 ppm of carbon dioxide was obtained in the same manner except that the moving layer was changed to carbon dioxide / TFPO = 9/1 and CBP was changed to BCP. .. This solution is referred to as composition 5.

<Ink adjustment>
(Hole injection layer composition)
PEDOT / PSS mixed water dispersion (1.0% by mass) 20 parts by mass Water 65 parts by mass ethoxyethanol 10 parts by mass Glycerin 5 parts by mass PEDOT / PSS: Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (Bayer) Baytron P Al 4083)

(Blue light emitting layer composition)
Composition 1 9.5 parts by mass Composition 2 0.5 parts by mass Toluene 40 parts by mass Isobutyl acetate 50 parts by mass

(Green light emitting layer composition)
Composition 1 9.5 parts by mass Composition 3 0.5 parts by mass Toluene 40 parts by mass Isobutyl acetate 50 parts by mass

(Red light emitting layer composition)
Composition 1 9.5 parts by mass Composition 4 0.5 parts by mass Toluene 40 parts by mass Isobutyl acetate 50 parts by mass

(Electron transport layer composition)
Composition 5 10 parts by mass TFPO 90 parts by mass

<Manufacturing of organic EL full-color display device>
FIG. 10 shows a schematic configuration diagram of an organic EL full-color display device. After patterning a substrate (NA45 manufactured by NH Technoglass Co., Ltd.) in which an ITO transparent electrode (102) was formed on a glass substrate 101 as an anode at a pitch of 100 μm, the ITO transparent electrode (102) was patterned between the ITO transparent electrodes on the glass substrate. A partition 103 (width 20 μm, thickness 2.0 μm) of photosensitive polyimide was formed by photolithography. The hole injection layer composition having the above composition was discharged and injected between the polyimide partition walls on the ITO electrode using an inkjet head (“KM512L” manufactured by Konica Minolta), and dried at 200 ° C. for 10 minutes to obtain a positive layer thickness of 40 nm. A hole injection layer 104 was prepared. The above-mentioned blue light emitting layer composition, green light emitting layer composition, and red light emitting layer composition are similarly ejected and injected onto the hole injection layer using an inkjet head, and the respective light emitting layers (105B, 105G, 105R) was formed. Subsequently, the electron transport layer composition was similarly ejected and injected using an inkjet head to form an electron transport layer (106) on each layer of the light emitting layer 105, which also served as a hole blocking function. Finally, Al (107) was vacuum-deposited on the electron transport layer 106 as a cathode to produce an organic EL device.
It was found that the produced organic EL element emits blue, green, and red light by applying a voltage to each electrode, and can be used as a full-color display device.

[Example 6]
As a p-type material for the bulk heterojunction layer, PCPDTBT, a low bandgap polymer described in Macromolecules 2007, 40, 1981, was synthesized and used with reference to non-patent documents (Nature Mat. Vol. 6 (2007), p497). Moreover, PCBM (purchased from Frontier Carbon Co., Ltd.) was used as the n-type material.

<Manufacturing of organic photoelectric conversion element 1>
An indium tin oxide (ITO) transparent conductive film deposited at 140 nm on a glass substrate was patterned to a width of 2 mm by using ordinary photolithography technology and hydrochloric acid etching to form a transparent electrode.
The patterned transparent electrode was cleaned in the order of ultrasonic cleaning with a surfactant and ultrapure water, and ultrasonic cleaning with ultrapure water, dried with a nitrogen blow, and finally subjected to ultraviolet ozone cleaning. Baytron P4083 (manufactured by Stark Vitec), which is a conductive polymer, was spin-coated on this transparent substrate to a film thickness of 60 nm, and then heated and dried in the air at 140 ° C. for 10 minutes.
After that, the substrate was brought into the glove box and worked in a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 10 minutes in a nitrogen atmosphere.
Chlorobenzene obtained by bubbling carbon dioxide gas for 10 minutes was prepared, and the concentration of dissolved carbon dioxide was measured by gas chromatography and found to be 350 ppm. This chlorobenzene contains 1.0% by mass of PCBDTBT as a p-type semiconductor material and [6,6] -phenylC61-butyric acid methyl ester (abbreviation: PCBM) as an n-type semiconductor material (NANOM SPECTRA E100H manufactured by Frontier Carbon). To prepare a solution in which 2.0% by mass of the above and 2.4% by mass of 1,8-octanedithiol were dissolved, spin coating was performed at 1200 rpm for 60 seconds while filtering with a 0.45 μm filter, and at room temperature. It was dried for 30 minutes to obtain a photoelectric conversion part (bulk heterojunction layer).
Next, the substrate on which the bulk heterojunction layer was formed was installed in the vacuum vapor deposition apparatus. The element was set so that the shadow mask having a width of 2 mm was orthogonal to the transparent electrode, and the ^{pressure inside the vacuum vapor deposition machine was reduced to 10-3} Pa or less, and then lithium fluoride was vapor-deposited at 0.5 nm and Al was vapor-deposited at 80 nm. Finally, heating was performed at 120 ° C. for 30 minutes to obtain an organic photoelectric conversion element 1. The vapor deposition rate was 2 nm / sec, and the size was 2 mm square. The obtained organic photoelectric conversion element 1 was sealed with an aluminum cap and a UV curable resin under a nitrogen atmosphere.

<Evaluation of organic photoelectric conversion element>
(Evaluation of conversion efficiency)
The organic photoelectric conversion element produced above is irradiated with light having an intensity of ^{100 mW / cm 2 of a solar simulator (AM1.5G filter), and a mask having an effective area of 4.0 mm 2} is placed on the light receiving portion to obtain a short-circuit current density Jsc. (MA / cm ² ), open circuit voltage Voc (V), and curve factor (fill factor) FF were measured at four light receiving parts formed on the same element, respectively, and the average value was obtained. Further, when the photoelectric conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to Equation 2, the photoelectric conversion efficiency was 3.9%.
Equation 2 Jsc (mA / cm ² ) x Voc (V) x FF = η (%)
From the above, it can be seen that a highly efficient organic photoelectric conversion element can be produced by using the coating liquid of the present invention.

The present invention can be used for inks for manufacturing electronic devices, electronic devices, organic electroluminescence devices, and organic photoelectric conversion elements.

11 Supercritical fluid 12 Pump 13 Modifier 14 Injector 15 Column 16 Column open 17 Detector 18 Pressure regulating valve 41 Display 53 Pixel 55 Scan line 56 Data line 60 Organic EL element 61 Switching transistor 62 Drive transistor 63 Capacitor 67 Power supply line 101 Glass Substrate 102 ITO transparent electrode 103 Partition 104 Hole injection layer 105B, 105G, 105R Light emitting layer 106 Electron transport layer 107 Cathode (Al)
200 Bulk heterojunction type organic photoelectric conversion element 201 Substrate 202 Transparent electrode (anode)
203 Counter electrode (cathode)
204 Photoelectric converter (bulk heterojunction layer)
205 Charge recombination layer 206 Second photoelectric conversion unit 207 Hole transport layer 208 Electron transport layer 209 First photoelectric conversion unit A Display unit B Control unit

Claims (14)

A method for producing a coating liquid containing an organic compound and an organic solvent.
In the coating liquid, the dissolved carbon dioxide concentration with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is within the range of 1 ppm or more and the saturation concentration with respect to the organic solvent.
The step of mixing the organic compound and carbon dioxide,
Using supercritical fluids, have a step of separating a substance in a solution containing an organic compound,
A method for producing a coating liquid, wherein the dissolved carbon dioxide contains carbon dioxide derived from supercritical carbon dioxide. The method for producing a coating liquid according to claim 1, wherein the coating liquid is a coating liquid for manufacturing an electronic device. The method for producing a coating liquid according to claim 1 or 2 , wherein the coating liquid is an ink for an inkjet. A coating solution containing an organic compound and an organic solvent.
The concentration of dissolved carbon dioxide with respect to the organic solvent under the conditions of 50 ° C. or lower and atmospheric pressure is within the range of 1 ppm or more and the saturation concentration with respect to the organic solvent, and the dissolved carbon dioxide is carbon dioxide derived from supercritical carbon dioxide. A coating liquid characterized by containing. The coating liquid according to claim 4 , wherein the dissolved carbon dioxide concentration is in the range of 5 to 1000 ppm under the above conditions. If the oxygen in the coating liquid is present than 1ppm, the dissolved carbon dioxide concentration, under said conditions, claims, characterized in that included within the scope of 1.0 to 100,000 times the concentration of dissolved oxygen 4 Alternatively, the coating liquid according to claim 5. The coating liquid according to any one of claims 4 to 6 , wherein the coating liquid is a coating liquid for manufacturing an electronic device. The coating liquid according to claim 7 , wherein the electronic device is a light emitting device. The coating solution according to any one of claims 4 to 8 , wherein the organic compound is an organic electroluminescence material. The coating liquid according to any one of claims 4 to 9 , wherein the coating liquid is an ink for an inkjet. An ink for manufacturing an electronic device, which comprises the coating liquid according to any one of claims 4 to 10. An electronic device having an organic functional layer formed by using the coating liquid according to any one of claims 4 to 10. An organic electroluminescence device having an organic functional layer formed by using the coating liquid according to any one of claims 4 to 10. A photoelectric conversion element having an organic functional layer formed by using the coating liquid according to any one of claims 4 to 10.

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